U.S. patent application number 12/880883 was filed with the patent office on 2011-03-10 for lithium-ion secondary battery.
This patent application is currently assigned to Boston-Power, Inc.. Invention is credited to Richard V. Chamberlain, II, Christina M. Lampe-Onnerud, Per Onnerud, Yanning Song.
Application Number | 20110059349 12/880883 |
Document ID | / |
Family ID | 38710521 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110059349 |
Kind Code |
A1 |
Lampe-Onnerud; Christina M. ;
et al. |
March 10, 2011 |
LITHIUM-ION SECONDARY BATTERY
Abstract
A lithium-ion battery includes a cathode that includes an active
cathode material. The active cathode material includes a cathode
mixture that includes a lithium cobaltate and a manganate spinel a
manganate spinel represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 or
Li.sub.(1+x1)Mn.sub.2O.sub.z1. The lithium cobaltate and the
manganate spinel are in a weight ratio of lithium
cobaltate:manganate spinel between about 0.9:0.1 to about 0.6:0.4.
A lithium-ion battery pack employs a cathode that includes an
active cathode material as described above. A method of forming a
lithium-ion battery includes the steps of forming an active cathode
material as described above; forming a cathode electrode with the
active cathode material; and forming an anode electrode in
electrical contact with the cathode via an electrolyte.
Inventors: |
Lampe-Onnerud; Christina M.;
(Framingham, MA) ; Onnerud; Per; (Framingham,
MA) ; Song; Yanning; (Chelmsford, MA) ;
Chamberlain, II; Richard V.; (Fairfax Station, VA) |
Assignee: |
Boston-Power, Inc.
Westborough
MA
|
Family ID: |
38710521 |
Appl. No.: |
12/880883 |
Filed: |
September 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12317487 |
Dec 22, 2008 |
7811708 |
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12880883 |
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PCT/US2007/014591 |
Jun 22, 2007 |
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12317487 |
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11485068 |
Jul 12, 2006 |
7811707 |
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PCT/US2007/014591 |
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11474056 |
Jun 23, 2006 |
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11485068 |
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PCT/US2005/047383 |
Dec 23, 2005 |
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11474056 |
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11821102 |
Jun 21, 2007 |
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PCT/US2005/047383 |
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PCT/US2005/047383 |
Dec 23, 2005 |
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11821102 |
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60639275 |
Dec 28, 2004 |
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60680271 |
May 12, 2005 |
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60699285 |
Jul 14, 2005 |
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Current U.S.
Class: |
429/156 ;
252/182.1; 29/623.1 |
Current CPC
Class: |
H01M 2004/021 20130101;
H01M 10/0436 20130101; H01M 10/0525 20130101; H01M 50/103 20210101;
Y02E 60/10 20130101; H01M 6/42 20130101; H01M 10/425 20130101; H01M
10/058 20130101; Y10T 29/49108 20150115; H01M 4/1391 20130101; H01M
4/133 20130101; H01M 4/525 20130101; H01M 4/131 20130101; Y10T
29/49115 20150115; H01M 4/505 20130101; H01M 4/485 20130101; H01M
4/364 20130101 |
Class at
Publication: |
429/156 ;
252/182.1; 29/623.1 |
International
Class: |
H01M 10/02 20060101
H01M010/02; H01M 4/525 20100101 H01M004/525; H01M 10/38 20060101
H01M010/38 |
Claims
1-28. (canceled)
29. An active cathode material, comprising a mixture that includes:
a) a lithium nickelate represented by the empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where x4
is equal to or greater than 0.1 and less than 1.3, x5 is equal to
or greater than 0.0 and equal to or less than 0.2, y4 is equal to
or greater than 0.0 and equal to or less than 0.2, z4 is equal to
or greater than 0.0 and equal to or less than about 0.2, A* is at
least one member of the group consisting of barium, magnesium, and
calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1; and b) at least one of i) a lithium cobaltate that
optionally includes a modifier of at least one of the lithium and
cobalt atoms, wherein the lithium modifier is at least one of
magnesium and sodium, and the cobalt modifier is at least one of
magnesium, sodium, aluminum, manganese, boron, titanium and nickel,
and at least one of a manganate spinel and an olivine compound, and
ii) a lithium nickelate represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2, where 0.05<x3<1.2 and
0<z3<0.5 and M' is one or more elements selected from the
group consisting of cobalt, manganese, aluminum, boron, titanium,
magnesium, calcium and strontium.
30. The active cathode material of claim 29, wherein x5 is equal to
zero.
31. The active cathode material of claim 30, wherein the lithium
cobaltate has the empirical formula of LiCoO.sub.2.
32. The active cathode material of claim 30, wherein a lithium
nickelate of the active cathode material is
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2.
33. The active cathode material of claim 32, further including a
manganate spinel having a formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where x1 is
equal to or greater than 0.01 and equal to or less than 0.3, y1 is
greater than 0.0 and equal to or less than 0.3, z1 is equal to or
greater than 3.9 and equal to or less than 4.1, and A' is at least
one member of the group consisting of magnesium, aluminum, cobalt,
nickel and chromium.
34. The active cathode material of claim 33, wherein the active
cathode material includes the lithium cobaltate, and wherein the
ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.(1+x1)(Mn.sub.1-y1A'.sub-
.y1).sub.(2-x1)O.sub.z1:lithium cobaltate is between about 0.05 and
about 0.8:between 0.3 and about 0.7:between about 0.05 and about
0.8.
35. The active cathode material of claim 30, wherein the active
cathode includes the lithium cobaltate, and at least one of a
manganate spinel and an olivine compound.
36. The active cathode material of claim 30 including a manganate
spinel having a formula of Li.sub.(1+x7)Mn.sub.(2-y7)O.sub.z7,
where x7 and y7 are each independently equal to or greater than 0.0
and equal to or less than 1.0, and z7 is equal to or greater than
3.9 and equal to or less than 4.2.
37. A lithium-ion battery comprising an active cathode material
having a mixture that includes: a) a lithium nickelate represented
by the empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is equal to or greater than 0.1 and less than 1.3, x5 is equal
to or greater than 0.0 and equal to or less than 0.2, y4 is equal
to or greater than 0.0 and equal to or less than 0.2, z4 is equal
to or greater than 0.0 and equal to or less than about 0.2, A* is
at least one member of the group consisting of barium, magnesium,
and calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1; and b) at least one of i) a lithium cobaltate that
optionally includes a modifier of at least one of the lithium and
cobalt atoms, wherein the lithium modifier is at least one of
magnesium and sodium, and the cobalt modifier is at least one of
magnesium, sodium, aluminum, manganese, boron, titanium, nickel,
and at least one of a manganate spinel and an olivine compound, and
ii) a lithium nickelate represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2 where 0.05<x3<1.2 and
0<z3<0.5 and M' is one or more elements selected from the
group consisting of cobalt, manganese, aluminum, boron, titanium,
magnesium, calcium and strontium.
38. A battery pack comprising a plurality of cells, wherein each of
the cells includes an active cathode material including a cathode
mixture that includes: a) a lithium nickelate represented by the
empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is equal to or greater than 0.1 and less than 1.3, x5 is equal
to or greater than 0.0 and equal to or less than 0.2, y4 is equal
to or greater than 0.0 and equal to or less than 0.2, z4 is equal
to or greater than 0.0 and equal to or less than about 0.2, A* is
at least one member of the group consisting of barium, magnesium,
and calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1; and b) at least one of i) a lithium cobaltate that
optionally includes a modifier of at least one of the lithium and
cobalt atoms, wherein the lithium modifier is at least one of
magnesium and sodium, and the cobalt modifier is at least one of
magnesium, sodium, aluminum, manganese, boron, titanium, nickel,
and at least one of a manganate spinel and an olivine compound, and
ii) a lithium nickelate represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2 where 0.05<x3<1.2 and
0<z3<0.5 and M' is one or more elements selected from the
group consisting of cobalt, manganese, aluminum, boron, titanium,
magnesium, calcium and strontium.
39. The battery pack of claim 38, wherein the cells are in series
and no cells are connected in parallel.
40. An active cathode material, comprising a mixture that includes:
a) a lithium nickelate represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2 where 0.05<x3<1.2 and
0<z3<0.5 and M' is one or more elements selected from the
group consisting of cobalt, manganese, aluminum, boron, titanium,
magnesium, calcium and strontium; and b) at least one of i) a
lithium cobaltate that optionally includes a modifier of at least
one of the lithium and cobalt atoms, wherein the lithium modifier
is at least one of magnesium and sodium, and the cobalt modifier is
at least one of magnesium, sodium, aluminum, manganese, boron,
titanium and nickel, and at least one of a manganate spinel and an
olivine compound, and ii) a lithium nickelate represented by the
empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where x4
is equal to or greater than 0.1 and less than 1.3, x5 is equal to
or greater than 0.0 and equal to or less than 0.2, y4 is equal to
or greater than 0.0 and equal to or less than 0.2, z4 is equal to
or greater than 0.0 and equal to or less than about 0.2, A* is at
least one member of the group consisting of barium, magnesium, and
calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1.
41. A lithium ion battery comprising a active cathode material
having a mixture that includes: a) a lithium nickelate represented
by an empirical formula of Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2
where 0.05<x3<1.2 and 0<z3<0.5 and M' is one or more
elements selected from the group consisting of cobalt, manganese,
aluminum, boron, titanium, magnesium, calcium and strontium; and b)
at least one of i) a lithium cobaltate that optionally includes a
modifier of at least one of the lithium and cobalt atoms, wherein
the lithium modifier is at least one of magnesium and sodium, and
the cobalt modifier is at least one of magnesium, sodium, aluminum,
manganese, boron, titanium, nickel, and at least one of a manganate
spinel and an olivine compound, and ii) a lithium nickelate
represented by the empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is equal to or greater than 0.1 and less than 1.3, x5 is equal
to or greater than 0.0 and equal to or less than 0.2, y4 is equal
to or greater than 0.0 and equal to or less than 0.2, z4 is equal
to or greater than 0.0 and equal to or less than about 0.2, A* is
at least one member of the group consisting of barium, magnesium,
and calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1.
42. A battery pack comprising a plurality of cells, wherein each of
the cells includes an active cathode material including a cathode
mixture that includes: a) a lithium nickelate represented by an
empirical formula of Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2 where
0.05<x3<1.2 and 0<z3<0.5 and M' is one or more elements
selected from the group consisting of cobalt, manganese, aluminum,
boron, titanium, magnesium, calcium and strontium; and b) at least
one of i) a lithium cobaltate that optionally includes a modifier
of at least one of the lithium and cobalt atoms, wherein the
lithium modifier is at least one of magnesium and sodium, and the
cobalt modifier is at least one of magnesium, sodium, aluminum,
manganese, boron, titanium, nickel, and at least one of a manganate
spinel and an olivine compound, and ii) a lithium nickelate
represented by the empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is equal to or greater than 0.1 and less than 1.3, x5 is equal
to or greater than 0.0 and equal to or less than 0.2, y4 is equal
to or greater than 0.0 and equal to or less than 0.2, z4 is equal
to or greater than 0.0 and equal to or less than about 0.2, A* is
at least one member of the group consisting of barium, magnesium,
and calcium, Q is at least one member of the group consisting of
aluminum, manganese and boron, and a is greater than about 1.5 and
less than 2.1.
43. The battery pack of claim 42, wherein the cells are in series
and no cells are connected in parallel.
44. The battery pack of claim 42, wherein each cell is individually
controlled and monitored.
45. An active cathode material, comprising a mixture that includes:
i) a) at least one of a lithium cobaltate and a lithium nickelate,
wherein the lithium cobaltate is a modified lithium cobaltate with
a lithium modifier of the lithium cobaltate, and wherein the
lithium modifier is at least one member selected from the group
consisting of magnesium (Mg) and sodium (Na), and wherein the
lithium nickelate is represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where:
x4 is greater than 0.1 and less than 1.3; x5 is greater than 0.0
and equal to or less than 0.2 y4 is greater than 0.0 and equal to
or less than 0.2 z4 is greater than 0.0 and equal to or less than
0.2; A* is at least one member of the group consisting of barium,
magnesium and calcium Q is at least one member of the group
consisting of aluminum, manganese and boron; and a is greater than
about 1.5 and less than about 2.1; and b) at least one of a
manganate spinel and an olivine compound, wherein the manganate
spinel is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 where: x1 is
equal to or greater than 0.01 and equal to or less than 0.3; y1 is
greater than 0.0 and equal to or less than 0.3; z1 is equal to or
greater than 3.9 and equal to or less than 4.1; and A' is at least
one member of the group consisting of magnesium, aluminum, cobalt,
nickel and chromium, and wherein the olivine compound is
represented by an empirical formula of
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where: x2 is equal to or greater
than 0.0 and equal to or less than 0.2; and M is at least one
member of the group consisting of iron, manganese, cobalt and
magnesium; and A'' is at least one member of the group consisting
of sodium, magnesium, calcium, potassium, nickel and niobium; or
ii) a) a lithium nickelate represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where:
x4 is greater than 0.1 and less than 1.3; x5 is greater than 0.0
and equal to or less than 0.2 y4 is greater than 0.0 and equal to
or less than 0.2 z4 is greater than 0.0 and equal to or less than
0.2; A* is at least one member of the group consisting of barium,
magnesium and calcium Q is at least one member of the group
consisting of aluminum, manganese and boron; and a is greater than
about 1.5 and less than about 2.1; and b) a manganate spinel
represented by an empirical formula of
Li.sub.(i+x7)Mn.sub.(2-y7)O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0, and z7 is equal to or greater than 3.9 and equal to or
less than 4.2.
46. The active cathode material of claim 45, wherein the lithium
cobaltate further includes a cobalt modifier, wherein the cobalt
modifier includes at least one member of the group consisting of
manganese (Mn), aluminum (Al), boron (B), titanium (Ti), magnesium
(Mg), calcium (Ca) and strontium (Sr).
47. The active cathode material of claim 45, wherein the lithium
nickelate is coated with LiCoO.sub.2.
48. The active cathode material of claim 47, where in the coating
is a gradient coating or a spot-wise coating.
49. The active cathode material of claim 45, wherein the manganate
spinel is Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1,
wherein x.sub.1, y.sub.1 and z.sub.1 are as defined in claim
45.
50. The active cathode material of claim 49, wherein a ratio of
lithium-cobaltate:manganate spinel:lithium nickelate is in a ratio
of between about 0.05 and about 0.3:between about 0.05 and about
0.30:between about 0.4 and about 0.9.
51. The active cathode material of claim 45, wherein the lithium
nickelate is Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2.
52. The active cathode material of claim 51, wherein the lithium
nickelate is coated with LiCoO.sub.2.
53. The active cathode material of claim 52, including the
manganate spinel.
54. The active cathode material of claim 53, wherein the ratio of
lithium nickelate-to-manganate spinel is between about 0.9:0.1 and
about 0.3:0.7.
55. The active cathode material of claim 45, including at least two
lithium nickelates and the manganate spinel.
56. The active cathode material of claim 55, wherein the lithium
nickelate and manganate spinel are in a ratio of lithium
nickelate:manganate spinel of between about 0.05 and 0.8:between
about 0.05 and about 0.9.
57. The active cathode material of claim 45, including the lithium
nickelate and the olivine compound having the formula of
Li.sub.(1-x2)A''.sub.x2MPO.sub.4, wherein x.sub.2 is as defined in
claim 45, and where M is iron or manganese.
58. The active cathode material of claim 57, wherein the lithium
nickelate and olivine compound are in a ratio of lithium
nickelate:olivine compound between about 0.9:0.1 and about
0.5:0.5.
59. The active cathode material of claim 57, including at least two
lithium nickelates and the olivine compound having the formula
Li.sub.(1-x2)A''.sub.x2MPO.sub.4, where M is iron or manganese.
60. The active cathode material of claim 59, wherein the olivine
compound is coated with carbon.
61. The active cathode material of claim 60, wherein the lithium
nickelate and olivine compound are in a ratio of lithium
nickelate:olivine compound between about 0.05 and about 0.9:between
about 0.05 and 0.9.
62. The active cathode material of claim 59, wherein the olivine
compound is at least one of LiFePO.sub.4 and LiMnPO.sub.4.
63. The active cathode material of claim 62, wherein one of the
lithium nickelates is represented by
Li(Ni.sub.1/3CO.sub.1/3Mn.sub.1/3)O.sub.2, and another lithium
nickelate is represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, wherein
x.sub.4, x.sub.5, y.sub.4 and z.sub.4 are as defined in claim
45.
64. The active cathode material of claim 63, wherein the ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.x4A*.sub.x5Ni.sub.(1-y4--
z4)Co.sub.y4Q.sub.z4O.sub.a:olivine compound is in a range of
between about 0.05 and about 0.8:between about 0.05 and about
0.7:between about 0.05 and about 0.9.
65. The active cathode material of claim 45, including the
manganate spinel, the lithium nickelate and the olivine
compound.
66. The active cathode material of claim 65, wherein the ratio of
manganate spinel:olivine compound:lithium nickelate is between
about 0.05-0.9:about 0.05-0.9:about 0.05-0.9.
67. The active cathode material of claim 45, further including a
lithium nickelate having the formula
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2.
68. The active cathode material of claim 67, wherein the ratio of
Li((Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.x4A*.sub.x5Ni.sub.(1-y4-
-z4)Co.sub.y4Q.sub.z4O.sub.a is between 0.7:0.3 to about
0.3:0.7.
69. The active cathode material of claim 45, including the lithium
nickelate, the lithium cobaltate and the olivine compound.
70. The active cathode material of claim 69, wherein the ratio of
lithium cobaltate:olivine compound:lithium nickelate is in a ratio
of between about 0.05 and about 0.3:between about 0.05 and about
0.3:between about 0.4 and about 0.9.
71. The active cathode material of claim 45, including both the
lithium cobaltate and the lithium nickelate.
72. A lithium-ion battery having a cathode that includes an active
cathode material, the active cathode material comprising a cathode
mixture that includes: i) a) at least one of a lithium cobaltate
and a lithium nickelate, wherein the lithium cobaltate is a
modified lithium cobaltate with a lithium modifier of the lithium
cobaltate, and wherein the lithium modifier is at least one member
selected from the group consisting of magnesium and sodium, and
wherein the lithium nickelate is represented by an empirical
formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1; and b) at least one of a
manganate spinel and an olivine compound, wherein the manganate
spinel is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y1).sub.2-x1O.sub.z1, where x1 is
equal to or greater than 0.01 and equal to or less than 0.3, y1 is
greater than 0.0 and equal to or less than 0.3, z1 is equal to or
greater than 3.9 and equal to or less than 4.1, and A' is at least
one member of the group consisting of magnesium, aluminum, cobalt,
nickel and chromium, and wherein the olivine compound is
represented by an empirical formula of
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where x2 is equal to or greater
than 0.0 and equal to or less than 0.2, M is at least one member of
the group consisting of iron, manganese, cobalt and magnesium, and
A'' is at least one member of the group consisting of sodium,
magnesium, calcium, potassium, nickel and niobium, or ii) a) a
lithium nickelate represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1; and b) a manganate spinel
represented by an empirical formula of
Li.sub.(1-x7)Mn.sub.(2-y7)O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0, and z7 is equal to or greater than 3.9 and equal to or
less than 4.2.
73. A method of forming a lithium-ion battery, comprising the step
of forming an active cathode material including a cathode mixture
that includes: i) a) at least one of a lithium cobaltate and a
lithium nickelate, wherein the lithium cobaltate is a modified
lithium cobaltate with a lithium modifier of the lithium cobaltate,
and wherein the lithium modifier is at least one member selected
from the group consisting of magnesium (Mg) and sodium (Na), and
wherein the lithium nickelate is represented by an empirical
formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1; and b) at least one of a
manganate spinel and an olivine compound, wherein the manganate
spinel is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y1).sub.2-x1O.sub.z1, where x1 is
equal to or greater than 0.01 and equal to or less than 0.3, y1 is
greater than 0.0 and equal to or less than 0.3, z1 is equal to or
greater than 3.9 and equal to or less than 4.1, and A' is at least
one member of the group consisting of magnesium, aluminum, cobalt,
nickel and chromium, and wherein the olivine compound is
represented by an empirical formula of
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where x2 is equal to or greater
than 0.0 and equal to or less than 0.2, M is at least one member of
the group consisting of iron, manganese, cobalt and magnesium, and
A'' is at least one member of the group consisting of sodium,
magnesium, calcium, potassium, nickel and niobium, or ii) a) a
lithium nickelate represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1; and b) a manganate spinel
represented by an empirical formula of
Li.sub.(1+x7)Mn.sub.(2-y7)O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0, and z7 is equal to or greater than 3.9 and equal to or
less than 4.2; iii) forming a cathode electrode with the active
cathode material; and iv) forming an anode electrode in electrical
contact with the cathode electrode via an electrolyte, thereby
forming a lithium-ion battery.
74. A battery pack comprising a plurality of cells, wherein each of
the cells includes an active cathode material including a cathode
mixture that includes: i) a) at least one of a lithium cobaltate
and a lithium nickelate, wherein the lithium cobaltate is a
modified lithium cobaltate with a lithium modifier of the lithium
cobaltate, and wherein the lithium modifier is at least one member
selected from the group consisting of magnesium (Mg) and sodium
(Na), and wherein the lithium nickelate is represented by an
empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1, and b) at least one of a
manganate spinel and an olivine compound, wherein the manganate
spinel is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y1).sub.2-x1O.sub.z1, where x1 is
equal to or greater than 0.01 and equal to or less than 0.3, y1 is
greater than 0.0 and equal to or less than 0.3, z1 is equal to or
greater than 3.9 and equal to or less than 4.1, and A' is at least
one member of the group consisting of magnesium, aluminum, cobalt,
nickel and chromium, and wherein the olivine compound is
represented by an empirical formula of
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where: x2 is equal to or greater
than 0.0 and equal to or less than 0.2; and M is at least one
member of the group consisting of iron, manganese, cobalt and
magnesium; and A'' is at least one member of the group consisting
of sodium, magnesium, calcium, potassium, nickel and niobium; or
ii) a) a lithium nickelate represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, where
x4 is greater than 0.1 and less than 1.3, x5 is greater than 0.0
and equal to or less than 0.2, y4 is greater than 0.0 and equal to
or less than 0.2, z4 is greater than 0.0 and equal to or less than
0.2, A* is at least one member of the group consisting of barium,
magnesium and calcium, Q is at least one member of the group
consisting of aluminum, manganese and boron, and a is greater than
about 1.5 and less than about 2.1; and b) a manganate spinel
represented by an empirical formula of
Li.sub.(1+x7)Mn.sub.(2-y7)O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0, and z7 is equal to or greater than 3.9 and equal to or
less than 4.2.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/317,487, filed Dec. 22, 2008, which is a
continuation of International Application No. PCT/US2007/014591,
which designated the United States and was filed on Jun. 22, 2007,
published in English, which is a continuation of U.S. patent
application Ser. No. 11/485,068, filed Jul. 12, 2006, which is a
continuation-in-part of U.S. patent application Ser. No.
11/474,056, filed on Jun. 23, 2006, and to U.S. patent application
Ser. No. 11/474,056, filed on Jun. 23, 2006. U.S. patent
application Ser. No. 11/474,056 is a continuation-in-part of Int'l.
App. No. PCT/US2005/047383, which designated the U.S. and was filed
on Dec. 23, 2005 published in English, which claims the benefit of
U.S. Provisional Application No. 60/639,275 filed on Dec. 28, 2004,
U.S. Provisional Application No. 60/680,271 filed on May 12, 2005;
and U.S. Provisional Application No. 60/699,285 filed on Jul. 14,
2005. The entire teachings of the above-mentioned applications are
incorporated herein by reference.
INCORPORATION BY REFERENCE
[0002] U.S. patent application, filed on Jun. 22, 2007 under
Attorney's Docket No. 3853.1015-000, which is entitled "Low
Pressure Current Interrupt Device For Batteries"; U.S. patent
application, filed on Jun. 22, 2007 under Attorney's Docket No.
3853.1012-001, which is entitled "Integrated Current-Interrupt
Device For Lithium-Ion Cells"; U.S. Provisional Application No.
60/717,898, filed on Sep. 16, 2005; International Application No.
PCT/US2005/047383, filed on Dec. 23, 2005; U.S. patent application
Ser. No. 11/474,081, filed on Jun. 23, 2006; U.S. patent
application Ser. No. 11/474,056, filed on Jun. 23, 2006; U.S.
Provisional Application No. 60/816,977, filed on Jun. 28, 2006;
U.S. patent application Ser. No. 11/485,068, filed on Jul. 12,
2006; U.S. patent application Ser. No. 11/486,970, filed on Jul.
14, 2006; and U.S. Provisional Application No. 60/852,753, filed on
Oct. 19, 2006 are all incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0003] Rechargeable batteries, such as lithium-ion rechargeable
batteries, are widely used as electrical power for battery-powered
portable electronic devices, such as cellular telephones, portable
computers, camcorders, digital cameras, PDAs and the like. A
typical lithium-ion battery pack for such portable electronic
devices employs multiple cells that are configured in parallel and
in series. For example, a lithium-ion battery pack may include
several blocks connected in series where each block includes one or
more cells connected in parallel. Each block typically has an
electronic control that monitors voltage levels of the block. In an
ideal configuration, each of the cells included in the battery pack
is identical. However, when cells are aged and cycled, cells tend
to deviate from the initial ideal conditions, resulting in an
unbalanced cell pack (e.g., unidentical capacity, impedance,
discharge and charge rate). This unbalance among the cells may
cause over-charge or over-discharge during normal operation of the
rechargeable batteries, and in turn can impose safety concerns,
such as explosion (i.e., rapid gas release and possibility for
fire).
[0004] Traditionally, the conventional lithium-ion rechargeable
batteries have employed LiCoO.sub.2-type materials as the active
component of lithium-ion battery cathodes. For such a lithium-ion
cell employing LiCoO.sub.2-type active cathode materials to be
fully charged, the charge voltage is usually 4.20V. With lower
charging voltage, the capacity is lower, which corresponds to lower
utilization of active LiCoO.sub.2 materials. On the other hand,
with higher charging voltage, the cell is less safe. In general, it
is a challenge for LiCoO.sub.2-based lithium-ion cells to have a
high capacity, for example higher than about 3 Ah due to a high
safety concern. In order to minimize the safety concern, lowering
the charge voltage is one option. However, this will lower the cell
capacity, and in turn lower cell energy density. To obtain high
capacity, increasing the number of cells in one battery pack may be
another option rather than increasing the charge voltage. However,
the increase in the number of cells can result in increased
probability of unbalance among the cells, which can cause
over-charge or over-discharge during normal operation, as discussed
above.
[0005] The largest mainstream cell that is typically used in the
industry currently is a so-called "18650" cell. This cell has an
outer diameter of about 18 mm and a length of 65 mm. Typically, the
18650 cell utilizes LiCoO.sub.2 and has a capacity between 1800 mAh
and 2400 mAh but cells as high as 2600 mAh are currently being
used. It is generally believed that it is not safe to use
LiCoO.sub.2 in a larger cell than the 18650 cell because of a
safety concern associated with LiCoO.sub.2. Other cells larger than
the 18650 cells exist in the art, for example, "26650" cells having
an outer diameter of about 26 mm and a length of 65 mm. The 26650
cells typically do not contain LiCoO.sub.2 and have worse
performance characteristics in terms of Wh/kg and Wh/L than the
18650 cells employing LiCoO.sub.2.
[0006] Therefore, there is a need to develop new active cathode
materials for lithium-ion batteries that minimize or overcome the
above-mentioned problems. In particular, there is a need to develop
new active cathode materials that can enable manufacturing large
batteries, for example, larger than the conventional
LiCoO.sub.2-based batteries (e.g., 18650 cells) in volume and/or
Ah/cell.
SUMMARY OF THE INVENTION
[0007] The present invention is generally directed to (1) an active
cathode material that includes a mixture of at least one of a
lithium cobaltate and a lithium nickelate; and at least one of a
manganate spinel and an olivine compound, (2) a lithium-ion battery
having such an active cathode material, (3) a method of forming
such a lithium-ion battery, (4) a battery pack comprising one or
more cells, each of the cells including such an active cathode
material, and (5) a system that includes such a battery pack or
lithium-ion battery and a portable electronic device.
[0008] In one embodiment, the present invention is directed to an
active cathode material that includes a mixture of electrode
materials. The mixture includes: at least one of a lithium
cobaltate and a lithium nickelate; and at least one of a manganate
spinel and an olivine compound. The manganate spinel is represented
by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 where:
[0009] x1 and x2 are each independently equal to or greater than
0.01 and equal to or less than 0.3;
[0010] y1 and y2 are each independently greater than 0.0 and equal
to or less than 0.3;
[0011] z1 is equal to or greater than 3.9 and equal to or less than
4.1; and
[0012] A' is at least one member of the group consisting of
magnesium, aluminum, cobalt, nickel and chromium.
[0013] The olivine compound is represented by an empirical formula
of Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where:
[0014] x2 is equal to or greater than 0.05 and equal to or less
than 0.2, or
[0015] x2 is equal to or greater than 0.0 and equal to or less than
0.1; and
[0016] M is at least one member of the group consisting of iron,
manganese, cobalt and magnesium; and
[0017] A'' is at least one member of the group consisting of
sodium, magnesium, calcium, potassium, nickel and niobium.
[0018] In another embodiment, the present invention is directed to
an active cathode material that includes a mixture including: a
lithium nickelate selected from the group consisting of
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
represented by an empirical formula of
Li.sub.(1+x7)Mn.sub.2-y7O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0; and z7 is equal to or greater than 3.9 and equal to or
less than 4.2.
[0019] The present invention is also directed to a lithium-ion
battery having a cathode that includes an active cathode material.
The active cathode material includes a mixture of electrode
materials. The mixture includes: at least one of a lithium
cobaltate and a lithium nickelate; and at least one of a manganate
spinel and an olivine compound. The manganate spinel is represented
by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 where:
[0020] x1 and x2 are each independently equal to or greater than
0.01 and equal to or less than 0.3;
[0021] y1 and y2 are each independently equal to or greater than
0.0 and equal to or less than 0.3;
[0022] z1 is equal to or greater than 3.9 and equal to or less than
4.1; and
[0023] A' is at least one member of the group consisting of
magnesium, aluminum, cobalt, nickel and chromium.
[0024] The olivine compound is represented by an empirical formula
of Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where:
[0025] x2 is equal to or greater than 0.05 and equal to or less
than 0.2, or
[0026] x2 is equal to or greater than 0.0 and equal to or less than
0.1; and
[0027] M is at least one member of the group consisting of iron,
manganese, cobalt and magnesium; and
[0028] A'' is at least one member of the group consisting of
sodium, magnesium, calcium, potassium, nickel and niobium.
[0029] In one embodiment, the mixture includes: at least one of a
lithium cobaltate and a lithium nickelate; and at least one of a
manganate spinel and an olivine compound. The manganate spinel and
olivine compound are as described above. In another embodiment, the
mixture includes: a lithium nickelate selected from the group
consisting of a lithium cobaltate, LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
as described above. The battery has a capacity greater than about
3.0 Ah/cell.
[0030] In yet another embodiment, the present invention is directed
to a lithium-ion battery having a cathode that includes an active
cathode material, the active cathode material comprising a cathode
mixture that includes a lithium cobaltate and a manganate spinel
represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 where y1 and
y2 are each independently equal to or greater than 0.0 and equal to
or less than 0.3, and the other variables are as described above.
The lithium cobaltate and the manganate spinel are in a weight
ratio of lithium cobaltate:manganate spinel between about 0.95:0.05
to about 0.55:0.45.
[0031] Also included in the present invention is a battery pack
that includes one or more cells, preferably a plurality of cells.
The cell(s) of the battery pack are as described above for the
lithium-ion batteries of the invention. In one embodiment, the
mixture includes: at least one of a lithium cobaltate and a lithium
nickelate; and at least one of a manganate spinel and an olivine
compound. The manganate spinel and olivine compound are as
described above for the lithium-ion batteries of the invention. In
another embodiment, the mixture includes a lithium nickelate
selected from the group consisting of a lithium cobaltate,
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
as described above. Preferably the battery pack includes a
plurality of cells and at least one cell of the cells has a
capacity greater than about 3.0 Ah/cell. In yet another embodiment,
the mixture includes a lithium cobaltate and a manganate spinel
represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, wherein the
variables are as described above, and the lithium cobaltate and the
manganate spinel are in a weight ratio of lithium
cobaltate:manganate spinel between about 0.95:0.05 to about
0.55:0.45.
[0032] A method of forming a lithium-ion battery having a cathode
that includes an active cathode material as described above is also
included in the present invention. The method includes forming an
active cathode material as described above. The method further
includes the steps of forming a cathode electrode with the active
cathode material; and forming an anode electrode in electrical
contact with the cathode electrode via an electrolyte, thereby
forming a lithium-ion battery
[0033] A system that includes a portable electronic device and a
battery pack as described above is also included in the present
invention.
[0034] The lithium-ion batteries of the invention, which employ a
novel blend of two or more different types of active cathode
materials in the positive electrode, have safer chemistry
characteristics than conventional lithium-ion batteries that solely
employ LiCoO.sub.2 as the active material of the lithium-ion
battery cathodes. In particular, an active cathode material of the
invention enables manufacturing of large batteries, e.g., larger
than the 18650 cells, for use in these mobile devices partly due to
its safety and high capacity in terms of energy density and power
density. The present invention also allows for economical
manufacturing of larger cells compared to what is common in today's
industry (e.g., the 18650 cells), in part due to lower cathode
costs and in part due to lower electronics costs. These higher
capacity type cells allow lower cost without sacrificing overall
safety. These higher capacity type cells can in turn minimize the
number of electronic components needed for charge control, which
allows lowering of electronic component costs overall for a battery
pack utilizing multiple cells connected in series or parallel.
[0035] The present invention can be used in mobile electronic
devices such as portable computers, cell phones and portable power
tools. The present invention can also be used in batteries for
hybrid electric vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a sectional view of a cylindrical-shaped
lithium-ion battery typical of that used commercially today and
specifically representative of an 18650 type lithium-ion
battery.
[0037] FIG. 2 is a schematic representation of an example of an
oblong-shaped can for a lithium-ion battery of the invention.
[0038] FIG. 3 is a schematic circuitry showing how cells in the
invention are preferably connected when arranged together in a
battery pack.
[0039] FIG. 4 is a photographic top, see-through view of a battery
pack of the invention.
[0040] FIGS. 5(a)-5(d) are schematic drawings comparing different
spatial utilizations of different battery form factors including
the battery of this invention (FIG. 5(a)) and comparison examples
typical of commercial batteries used today including two 18650
cells in parallel (FIG. 5(b)), a prismatic cell containing a wound
jelly roll electrode structure (FIG. 5(c)) and a prismatic cell
containing a stacked electrode structure (FIG. 5(d)).
[0041] FIG. 6 is a graph showing typical charge curves of a battery
of the invention and a control battery at room temperature.
[0042] FIG. 7 is a graph showing relative capacity retention during
charge-discharge cycling at room temperature of a battery of the
invention and two control batteries: cycling conditions: constant
charge constant voltage (CCCV) charging using 0.7C constant charge
followed by constant voltage charge at 4.2 V and then 1C discharge
to 2.75 V.
[0043] FIG. 8 is a graph showing relative capacity retention during
charge-discharge cycling at 60.degree. C. of a battery of the
invention and a control battery under the conditions described in
FIG. 7.
[0044] FIG. 9 is a graph showing the rate capability for an average
and standard deviation of eight batteries of the invention and two
control commercial 18650 batteries where the batteries are charged
under the charge conditions described in FIG. 7 and discharged to
2.75 V at the rates indicated in the figure.
[0045] FIG. 10 is a graph showing the total heat of reaction of
cathode mixtures of the invention, which includes a lithium
cobaltate and a manganate spinel, and of the lithium cobaltate and
the manganate spinel, in DSC tests.
[0046] FIG. 11 is a graph showing the maximum heat flow during
reaction of cathode mixtures of the invention, which includes a
lithium cobaltate and a manganate spinel, in DSC tests.
[0047] FIG. 12 is a graph showing time spent by a lithium-ion
battery of the invention, which includes a cathode mixture that
includes a lithium cobaltate and a manganate spinel, prior to rapid
cell reaction (e.g., fire or explosion) during abuse testing.
[0048] FIG. 13 is a graph showing cyclability of a lithium-ion
battery of the invention, which includes 70 wt % of LiCoO.sub.2 and
30 wt % of Li.sub.i+x1Mn.sub.2O.sub.4 as an active cathode
material, and showing cyclability of two commercially available
18650 batteries with 100 wt % of LiCoO.sub.2 as an active cathode
material.
DETAILED DESCRIPTION OF THE INVENTION
[0049] The foregoing and other objects, features and advantages of
the invention will be apparent from the following more particular
description of preferred embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating the principles of the invention.
[0050] In one embodiment, the present invention relates to an
active cathode material mixture that can be employed in an
electrode of a lithium-ion battery that allows lithium to be
reversibly intercalated and extracted. The active cathode material
comprises a mixture that includes: at least one of a lithium
cobaltate and a lithium nickelate; and at least one of a manganate
spinel and an olivine compound.
[0051] A lithium nickelate that can be used in the invention
includes at least one modifier of either the Li atom or Ni atom, or
both. As used herein, a "modifier" means a substituent atom that
occupies a site of the Li atom or Ni atom, or both, in a crystal
structure of LiNiO.sub.2. In one embodiment, the lithium nickelate
includes only a modifier of Li atom ("Li modifier"). In another
embodiment, the lithium nickelate includes only a modifier of Ni
atom ("Ni modifier"). In yet another embodiment, the lithium
nickelate includes both of the Li and Ni modifiers. Examples of the
Li modifier include barium (Ba), magnesium (Mg), calcium (Ca) and
strontium (Sr). Examples of the Ni modifier include those modifiers
for Li and in addition aluminum (Al), manganese (Mn) and boron (B).
Other examples of the Ni modifier include cobalt (Co) and titanium
(Ti). Preferably, the lithium nickelate is coated with LiCoO.sub.2.
The coating can be a gradient coating or a spot-wise coating.
[0052] One particular type of a lithium nickelate that can be used
in the invention is represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2 where 0.05<x3<1.2 and
0<z3<0.5, and M' is one or more elements selected from a
group consisting of Co, Mn, Al, B, Ti, Mg, Ca and Sr. Preferably,
M' is one or more elements selected from a group consisting of Mn,
Al, B, Ti, Mg, Ca and Sr.
[0053] Another particular type of a lithium nickelate that can be
used in the invention is represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where x4
is equal to or greater than about 0.1 and equal to or less than
about 1.3; x5 is equal to or greater than 0.0 and equal to or less
than about 0.2; y4 is equal to or greater than 0.0 and equal to or
less than about 0.2; z4 is equal to or greater than 0.0 and equal
to or less than about 0.2; a is greater than about 1.5 and less
than about 2.1; A* is at least one member of the group consisting
of barium (Ba), magnesium (Mg) and calcium (Ca); and Q is at least
one member of the group consisting of aluminum (Al), manganese (Mn)
and boron (B). Preferably, y4 is greater than zero. In one
preferred embodiment, x5 is equal to zero, and z4 is greater than
0.0 and equal to or less than about 0.2. In another embodiment, z4
is equal to zero, and x5 is greater than 0.0 and equal to or less
than about 0.2. In yet another embodiment, x5 and z4 are each
independently greater than 0.0 and equal to or less than about 0.2.
In yet another embodiment, x5, y4 and z4 are each independently
greater than 0.0 and equal to or less than about 0.2. Various
examples of lithium nickelates where x5, y4 and z4 are each
independently greater than 0.0 and equal to or less than about 0.2
can be found in U.S. Pat. Nos. 6,855,461 and 6,921,609 (the entire
teachings of which are incorporated herein by reference).
[0054] A specific example of the lithium nickelate is
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2. A preferred specific
example is LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2. The spot-wise coated
cathode has LiCoO.sub.2 not fully coated on top of a nickelate core
particle, so that the higher reactivity nickelate is deactivated
and hence safer. The composition of
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 coated with LiCoO.sub.2
can naturally deviate slightly in composition from the
0.8:0.15:0.05 weight ratio between Ni:Co:Al. Deviation may be
approximately 10-15% for the Ni, 5-10% for Co and 2-4% for Al.
[0055] Another specific example of the lithium nickelate is
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. A preferred
specific example is LiCoO.sub.2-coated
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. The spot-wise
coated cathode has LiCoO.sub.2 not fully coated on top of a
nickelate core particle, so that the higher reactivity nickelate is
deactivated and hence safer. The composition of
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2 coated with
LiCoO.sub.2 can naturally deviate slightly in composition from the
0.03:0.9:0.1 weight ratio between Mg:Ni:Co. Deviation may be
approximately 2-4% for Mg, 10-15% for Ni and 5-10% for Co.
[0056] Another preferred nickelate that can be used in the present
invention is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2, which is
also called "333-type nickelate." This 333-type nickelate can be
optionally coated with LiCoO.sub.2 as described above.
[0057] Suitable examples of lithium cobaltates that can be used in
the invention include LiCoO.sub.2 that is modified by at least one
of modifiers of Li and Co atoms. Examples of the Li modifiers are
as described above for Li for LiNiO.sub.2. Examples of the Co
modifiers include the modifiers for Li and aluminum (Al), manganese
(Mn) and boron (B). Other examples include nickel (Ni) and titanium
(Ti). Particularly, lithium cobaltates represented by an empirical
formula of Li.sub.x6M'.sub.(1-y6)Co.sub.(1-z6)M''.sub.z6O.sub.2,
where x6 is greater than 0.05 and less than 1.2; y6 is equal to or
greater than 0 and less than 0.1, z6 is equal to or greater than 0
and less than 0.5; M' is at least one member of magnesium (Mg) and
sodium (Na) and M'' is at least one member of the group consisting
of manganese (Mn), aluminum (Al), boron (B), titanium (Ti),
magnesium (Mg), calcium (Ca) and strontium (Sr), can be used in the
invention.
[0058] Another example of lithium cobaltates that can be used in
the invention includes LiCoO.sub.2.
[0059] It is particularly preferred that the compounds have a
spherical-like morphology as this improves packing and production
characteristics.
[0060] Preferably, a crystal structure of each of the lithium
cobaltate and lithium nickelate is independently a R-3m type space
group (rhombohedral, including distorted rhombohedral).
Alternatively, a crystal structure of the lithium nickelate can be
in a monoclinic space group (e.g., P2/m or C2/m). In a R-3m type
space group, the lithium ion occupies the "3a" site (x=0, y=0 and
z=0) and the transition metal ion (i.e., Ni in a lithium nickelate
and Co in a lithium cobaltate) occupies the "3b" site (x=0, y=0,
z=0.5). Oxygen is located in the "6a" site (x=0, y=0, z=z0, where
z0 varies depending upon the nature of the metal ions, including
modifier(s) thereof).
[0061] Olivine compounds that can be used in the invention are
generally represented by a general formula
Li.sub.1-x2A''.sub.x2MPO.sub.4, where x2 is equal to or greater
than 0.05, or x2 is equal to or greater than 0.0 and equal to or
greater than 0.1; M is one or more elements selected from a group
consisting of Fe, Mn, Co, or Mg; and A'' is selected from a group
consisting of Na, Mg, Ca, K, Ni, Nb. Preferably, M is Fe or Mn.
More preferably, LiFePO.sub.4 or LiMnPO.sub.4, or both are used in
the invention. In a preferred embodiment, the olivine compounds are
coated with a material having high electrical conductivity, such as
carbon. In a more preferred embodiment, carbon-coated LiFePO.sub.4
or carbon-coated LiMnPO.sub.4 is used in the invention. Various
examples of olivine compounds where M is Fe or Mn can be found in
U.S. Pat. No. 5,910,382 (the entire teachings of which are
incorporated herein by reference).
[0062] The olivine compounds have typically a small change in
crystal structure upon charging/discharging, which makes the
olivine compounds superior in terms of cycle characteristic. Also,
safety is generally high even when a battery is exposed to a high
temperature environment. Another advantage of the olivine compounds
(e.g., LiFePO.sub.4 and LiMnPO.sub.4) is their relatively low
cost.
[0063] Manganate spinel compounds have a manganese base, such as
LiMn.sub.2O.sub.4. While the manganate spinet compounds typically
have low specific capacity (e.g., in a range of about 100 to 115
mAh/g), they have high power delivery when formulated into
electrodes and are typically safe in Willis of chemical reactivity
at higher temperatures. Another advantage of the manganate spinel
compounds is their relatively low cost.
[0064] One type of manganate spinel compounds that can be used in
the invention is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where A' is
one or more of Mg, Al, Co, Ni and Cr; x1 and x2 are each
independently equal to or greater than 0.01 and equal to or less
than 0.3; y1 and y2 are each independently equal to or greater than
0.0 and equal to or less than 0.3; z1 is equal to or greater than
3.9 and equal to or less than 4.1. Preferably, A' includes a
M.sup.3+ ion, such as Al.sup.3+, Co.sup.3+, Ni.sup.3+ and
Cr.sup.3+, more preferably Al.sup.3+. The manganate spinel
compounds of Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1
can have enhanced cyclability and power compared to those of
LiMn.sub.2O.sub.4.
[0065] In some embodiments where the cathode mixtures of the
invention include a manganate spinel, the manganate spinel for the
invention includes a compound represented by an empirical formula
of Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where y1
and y2 are each independently greater than 0.0 and equal to or less
than 0.3, and the other values are the same as described above.
[0066] In other embodiments where the cathode mixtures of the
invention include a manganate spinel, the manganate spinel for the
invention includes a compound represented by an empirical formula
of Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where x1
and z1 are each independently the same as described above.
[0067] Alternatively, the manganate spinel for the invention
includes a compound represented by an empirical formula of
Li.sub.1+x7Mn.sub.2-y7O.sub.z7 where x7 and y7 are each
independently equal to or greater than 0.0 and equal to or less
than 1.0; and z7 is equal to or greater than 3.9 and equal to or
less than 4.2.
[0068] Specific examples of the manganate spinel that can be used
in the invention include LiMn.sub.1.9Al.sub.0.1O.sub.4,
Li.sub.1+x1Mn.sub.2O.sub.4, Li.sub.1+x7Mn.sub.2-y7O.sub.4, and
their variations with Al and Mg modifiers. Various other examples
of manganate spinel compounds of the type
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 can be found
in U.S. Pat. Nos. 4,366,215; 5,196,270; and 5,316,877 (the entire
teachings of which are incorporated herein by reference).
[0069] The active cathode materials of the invention can be
prepared by mixing two or more active cathode components described
above (i.e., a lithium cobaltate, a lithium nickelate, a manganate
spinel and an olivine compound), preferably in a powdered form.
Generally, the olivine compounds, such as LiFePO.sub.4, manganate
spinel compounds, such as
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, and lithium
nickelates, such as Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2, have
high safety. Generally, lithium cobaltates, such as LiCoO.sub.2 and
lithium nickelates, such as
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and
Li.sub.x4Ni.sub.1-y4-z4Co.sub.y4Q.sub.z4O.sub.a-type compounds have
a high-energy density. General properties of some cathode
components for the cathode materials of the invention are
summarized in Table 1.
TABLE-US-00001 TABLE 1 Typical Attributes of Active Cathode
Materials of the Invention 1.sup.st Cycle Density C/20 Capacity 1C
Capacity Efficiency Cathode Material (g/cc) (mAh/g) (mAh/g) (%)
lithium cobaltate 5.05 150 145 96 lithium nickelate 4.80 210 180 92
olivine (M = Fe) 3.30 155 140 95 manganate spinel 4.20 120 115
94
[0070] Characteristics of the cathode materials of the invention
relate to capacity, cyclability, and safety. For example, the
cathode materials of the invention can exhibit different capacities
depending on the charge/discharge rate and other external
conditions, such as electrolyte choice and electrode formulation.
"Capacity" is defined herein as the number of Li ions that can
reversibly be removed from the crystal structures of lithium-based
materials, such as those of the invention. "Reversibility," as
defined herein, means that the structure substantially maintains
its integrity and that Li can be intercalated back to restore the
initial crystal structure. In theory, this is the definition of
capacity at an infinitely small rate. "Safety," as defined herein,
means structural stability or structural integrity; if a material
decomposes during cycling or is easily decomposed or causes gassing
at elevated temperatures, the material is considered unsafe,
particularly if the decomposition or gassing leads to initiation of
thermal runaway behavior inside the cell or produces high internal
pressure. Polarization behavior adds yet another dimension to
capacity and the effects of polarization behavior to performance of
a lithium-ion battery are determined by the interaction between the
lithium-ion cell and the control electronics of the battery pack or
application device using the lithium-ion cell.
[0071] Formulation of an electrode suitable for high energy and
power, and sufficient safety, can be achieved by a specific ratio
of components (i.e., a lithium cobaltate, a lithium nickelate, a
manganate spinel and an olivine compound) of the active cathode
materials of the invention.
[0072] In one embodiment, an active cathode material of the
invention includes a lithium nickelate that includes at least one
modifier of either the Li atom or Ni atom, or both. Preferably, the
lithium nickelate is represented by an empirical formula of
Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2 described above.
Alternatively, the lithium nickelate is represented by an empirical
formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a
described above. In a specific example, the lithium nickelate is
represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. Specific examples of the lithium nickelate
are as described above.
[0073] In a second embodiment, an active cathode material of the
invention includes a lithium cobaltate represented by an empirical
formula of Li.sub.x6Co.sub.(1-z6)M''.sub.z6O.sub.2 described above.
Specific examples of the lithium cobaltate are as described
above.
[0074] In a third embodiment, an active cathode material of the
invention includes an olivine compound represented by an empirical
formula of Li.sub.(1-x2)A''.sub.x2MPO.sub.4 described above.
Specific examples of the olivine compound are as described above.
In a preferred embodiment, M is iron or magnesium. In a preferred
embodiment, the olivine compound is coated with carbon.
[0075] In a fourth embodiment, an active cathode material of the
invention includes a lithium cobaltate, such as LiCoO.sub.2, and a
manganate spinel. The lithium cobaltate and manganate spinel,
including specific examples thereof, are as described above.
Preferably, the lithium cobaltate, and manganate spinel are in a
weight ratio of lithium cobaltate:manganate spinel between about
0.8:0.2 to about 0.4:0.6. In one example of the fourth embodiment,
the manganate spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In another
example of the fourth embodiment, the manganate spinel is
represented by Li.sub.1+x7Mn.sub.2-y7O.sub.z7, preferably
Li.sub.1+x7Mn.sub.2O.sub.z7 (e.g., Li.sub.1+x7Mn.sub.2O.sub.4). In
yet another example of the fourth embodiment, the manganate spinel
is represented by Li.sub.1+x1Mn.sub.2O.sub.z1.
[0076] In a fifth embodiment, an active cathode material of the
invention includes a lithium nickelate and a manganate spinel
represented by Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1
described above. The lithium nickelate and manganate spinel,
including specific examples thereof, are as described above.
Preferably, the lithium nickelate and manganate spinel are in a
weight ratio of lithium nickelate:manganate spinel between about
0.9:0.1 to about 0.3:0.7. In one example of the fifth embodiment,
the lithium nickelate is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2,
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 or
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. Preferably, the
lithium nickelate is LiCoO.sub.2-coated,
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 or
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. When
LiCoO.sub.2-coated, LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 or
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2 is used, the
lithium nickelate and manganate spinel are preferably in a weight
ratio of lithium nickelate-to-manganate spinel between about
0.9:0.1 to about 0.3:0.7. When
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 is used, the lithium
nickelate and manganate spinel are preferably in a weight ratio of
lithium nickelate:manganate spinet between about 0.7:0.3 to about
0.3:0.7.
[0077] In a sixth embodiment, an active cathode material of the
invention includes at least one lithium nickelate selected from the
group consisting of Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and
LiCoO.sub.2-coated LiNi.sub.0.8CO.sub.0.15Al.sub.0.05O.sub.2; and a
manganate spinel represented by Li.sub.1+x7Mn.sub.2-y7O.sub.z7,
preferably Li.sub.1+x1Mn.sub.2O.sub.4, such as LiMn.sub.2O.sub.4.
Preferably, the lithium nickelate and manganate spinet are in a
weight ratio of lithium nickelate:manganate spinel between about
0.9:0.1 to about 0.3:0.7. When
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 is used, the lithium
nickelate and manganate spinel are in a weight ratio of lithium
nickelate:manganate spinel between about 0.9:0.1 to about
0.5:0.5.
[0078] In a seventh embodiment, the active cathode material of the
invention includes a lithium cobaltate, such as LiCoO.sub.2, a
manganate spinet and a lithium nickelate. The lithium cobaltate,
manganate spinet and lithium nickelate, including specific examples
thereof, are as described above. Preferably, the lithium cobaltate,
manganate spinel and lithium nickelate are in a weight ratio of
lithium cobaltate:manganate spinel:lithium nickelate between about
0.05 and about 0.8:between about 0.05 and about 0.7 (e.g., between
about 0.05 and about 0.3, or between about 0.3 and about
0.7):between about 0.05 and about 0.9 (e.g., between about 0.4 and
about 0.9, or between about 0.05 and about 0.8). In one example,
the lithium nickelate is represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In a
second example, the lithium nickelate is represented by
Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2, more preferably
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 that is gradient- or
spot-wise coated with LiCoO.sub.2. In a third example, the lithium
nickelate is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2. In a fourth
example, the lithium nickelate includes at least one modifier of
both the Li and Ni atoms, such as
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2, and the manganate spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z. Preferably,
when Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a and
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 are used, the
lithium cobaltate, manganate spinel and lithium nickelate are in a
weight ratio of lithium cobaltate:manganate spinel:lithium
nickelate between about 0.05 and about 0.30:between about 0.05 and
about 0.30:between about 0.4 and about 0.9. In a fifth example, the
lithium nickelate is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 or
optionally LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and the manganate spinel
is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In this fifth
example, when Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 is used,
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2,
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 and lithium
cobaltate are in a weight ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.(1+x1)(Mn.sub.1-y1A'.sub-
.y2).sub.2-x2O.sub.z1:lithium cobaltate between about 0.05 and
about-0.8; between about 0.3 and about-0.7:between about 0.05
and-about 0.8.
[0079] In an eighth embodiment, an active cathode material of the
invention includes two or more lithium nickelates and a manganate
spinel. The lithium nickelates and manganate spinel, including
specific examples thereof, are as described above. Preferably,
lithium nickelates and manganate spinel are in a weight ratio of
lithium nickelates; manganate spinel between about 0.05 and about
0.8:between about 0.05 and about 0.9. Preferably, the manganate
spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In one
example, the lithium nickelates include a lithium nickelate
represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In
another example, the lithium nickelates includes a lithium
nickelate represented by Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2.
Alternatively, the lithium nickelates includes a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In a specific example, the lithium
nickelates include Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and a
lithium nickelate represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In
another specific example, the lithium nickelates include
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a lithium nickelate
that includes at least one modifier of both the Li and Ni atoms,
such as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a
where x5, y4 and z4 are each independently greater than 0.0 and
equal to or less than about 0.2. In yet another specific example,
the lithium nickelates include
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and a lithium nickelate
represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a, and the
manganate spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In this
specific example, the lithium nickelates and manganate spinel are
in a weight ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.x4A*.sub.x5Ni.s-
ub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a:Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).s-
ub.2-x2O.sub.z1 between about 0.05 and about 0.8:between about 0.05
and about 0.7:between about 0.05 and about 0.9.
[0080] In a ninth embodiment, an active cathode material of the
invention includes a lithium cobaltate, such as LiCoO.sub.2, and an
olivine compound represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4
described above, preferably coated with carbon. The lithium
cobaltate and olivine compound, including specific examples
thereof, are as described above. Preferably, the lithium cobaltate
and olivine compound are in a weight ratio of lithium
cobaltate:olivine compound between about 0.9:0.1 to about 0.3:0.7.
In one example, the olivine compound is represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese, such
as LiFePO.sub.4 and LiMnPO.sub.4. In this example, preferably, the
lithium cobaltate and olivine compound are in a weight ratio of
lithium cobaltate:olivine compound between about 0.8:0.2 to about
0.4:0.6.
[0081] In a tenth embodiment, an active cathode material of the
invention includes a lithium nickelate, and an olivine compound
represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4 described above,
preferably coated with carbon. The lithium nickelate and olivine
compound, including specific examples thereof, are as described
above. Preferably, the lithium nickelate and olivine compound are
in a weight ratio of lithium nickelate:olivine compound between
about 0.9:0.1 to about 0.3:0.7. In one example, the olivine
compound is represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M
is iron or manganese, such as LiFePO.sub.4 and LiMnPO.sub.4. In a
second example, the lithium nickelates include a lithium nickelate
represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In a
third example, the lithium nickelates includes a lithium nickelate
represented by Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2.
Alternatively, the lithium nickelates includes a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In a specific example, the lithium
nickelate is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and the
olivine compound is represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4
where M is iron or manganese. Preferably, in the second example,
the lithium nickelate and olivine compound are in a weight ratio of
lithium nickelate:olivine compound between about 0.9:0.1 to about
0.5:0.5. In a second specific example, the lithium nickelate is
represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a,
preferably
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2, and the olivine compound is represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese. In a
third specific example, the lithium nickelate is
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, preferably
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
the olivine compound is represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese.
Preferably, in the third specific example, the lithium nickelate
and olivine compound are in a weight ratio of lithium
nickelate:olivine compound between about 0.9:0.1 to about
0.3:0.7.
[0082] In an eleventh embodiment, an active cathode material of the
invention includes two or more lithium nickelates, and an olivine
compound, preferably an olivine compound represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese. The
lithium nickelates and olivine compound, including specific
examples thereof, are as described above. Preferably, the olivine
compound is coated with carbon. In this embodiment, the lithium
nickelates and olivine compound are in a weight ratio of lithium
nickelates:olivine compound between about 0.05 and about
0.9:between about 0.05 and 0.9. In one example, the lithium
nickelates include a lithium nickelate represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In
another example, the lithium nickelates includes a lithium
nickelate represented by Li.sub.x4Ni.sub.(1-z3)M'.sub.z3O.sub.2.
Alternatively, the lithium nickelates includes a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In a specific example, the lithium
nickelate is represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In one specific example, the olivine
compound is represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M
is iron or manganese, such as LiFePO.sub.4 and LiMnPO.sub.4, and
the lithium nickelates include
Li(Ni.sub.1/3CO.sub.1/3Mn.sub.1/3)O.sub.2 and a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In this example, the lithium nickelates and
olivine compound are preferably in a weight ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2, lithium
nickelate:olivine compound between about 0.05 and about 0.8:between
about 0.05 and about 0.7:between about 0.05 and about 0.9.
[0083] In a twelfth embodiment, an active cathode material of the
invention includes a lithium nickelate, a lithium cobaltate, such
as LiCoO.sub.2, and an olivine compound represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 described above. The lithium
nickelate, lithium cobaltate and olivine compound, including
specific examples thereof, are as described above. In this
embodiment, the lithium nickelate, lithium cobaltate and olivine
compound are preferably in a weight ratio of lithium
cobaltate:olivine compound:lithium nickelate between about 0.05 and
about 0.8:between about 0.05 and about 0.7:between about 0.05 and
about 0.9. In one example, the lithium nickelates include a lithium
nickelate represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a. In
another example, the lithium nickelates includes a lithium
nickelate represented by Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2.
Alternatively, the lithium nickelates includes a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In one specific example, the lithium
nickelate is represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a,
preferably
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2, and the olivine compound is represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese. In
this specific example, the lithium nickelate, lithium cobaltate and
olivine compound are preferably in a weight ratio of lithium
cobaltate:olivine compound:lithium nickelate between about 0.05 and
about 0.30:between about 0.05 and about 0.30:between about 0.4 and
about 0.9. In a second specific example, the lithium nickelate is
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2, and the olivine compound
is represented by Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron
or manganese. In the second specific example, preferably the
lithium nickelate, lithium cobaltate and olivine compound are in a
weight ratio of lithium nickelate:olivine:lithium cobaltate between
about 0.05-0.8:about 0.3-0.7:about 0.05-0.8. In a third specific
example, the lithium nickelate is
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, preferably
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
the olivine compound is represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese.
[0084] In a thirteenth embodiment, an active cathode material of
the invention includes a manganate spinel, an olivine compound,
preferably an olivine compound represented by
Li.sub.(1-x2)A''.sub.x2MPO.sub.4 where M is iron or manganese, and
a lithium nickelate. The manganate spinel, olivine compound and
lithium nickelate, including specific examples thereof, are as
described above. In this embodiment, manganate spinel, olivine
compound and lithium nickelate are preferably in a weight ratio of
manganate spinel:olivine:lithium nickelate between about
0.05-0.9:about 0.05-0.9:about 0.05-0.9. In one example, the
manganate spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In another
example, the manganate spinel is represented by
Li.sub.1+x7Mn.sub.2-y7O.sub.z7. In yet another example, the
manganate spinel is represented by Li.sub.1+x1Mn.sub.2O.sub.4, such
as LiMn.sub.2O.sub.4. In one specific example, the manganate spinel
is represented by
Li.sub.(1+x)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 and the lithium
nickelate includes at least one modifier of both the Li and Ni
atoms, such as a lithium nickelate represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. In a second specific example, the manganate
spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 and the
lithium nickelate is represented by
Li.sub.x3Ni.sub.(1-z3)M'.sub.z3O.sub.2, preferably
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, more preferably
LiCoO.sub.2-coated LiNi.sub.0.8CO.sub.0.15Al.sub.0.05O.sub.2. In a
third specific example, the manganate spinel is represented by
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y1).sub.2-x1Oz1 and the lithium
nickelate is Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2. In a fourth
specific example, the manganate is represented by
Li.sub.1+x7Mn.sub.2-y7O.sub.4 or Li.sub.1+x1Mn.sub.2O.sub.4, or is
a variation thereof modified with Al and Mg, and the lithium
nickelate is selected from the group consisting of
Li(Ni.sub.1/3Co.sub.i/3Mn.sub.1/3)O.sub.2, and LiCoO.sub.2-coated
LiNi.sub.0.8CO.sub.0.15Al.sub.0.05O.sub.2.
[0085] In a fourteenth embodiment, an active cathode material of
the invention includes two or more lithium nickelates as described
above. In one example, the active cathode material includes
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2. In a specific example,
the active cathode material includes
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 and a lithium nickelate
including at least one modifier of both the Li and Ni atoms, such
as a lithium nickelate represented by
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where
x5, y4 and z4 are each independently greater than 0.0 and equal to
or less than about 0.2. Preferably, in this example, the lithium
nickelates are in a weight ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:Li.sub.x4A*.sub.x5Ni.sub.(1-y4--
z4)Co.sub.y4Q.sub.z4O.sub.a between about 0.7:0.3 to about 0.3:0.7.
In another specific example, the active cathode material includes
Li(Ni.sub.1/3CO.sub.1/3Mn.sub.1/3)O.sub.2 and
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, more preferably
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2.
Preferably, in this example, the lithium nickelates are in a weight
ratio of
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2:LiNi.sub.0.8Co.sub.0.15Al.sub.0-
.05O.sub.2 between about 0.8:0.2 to about 0.2:0.8.
[0086] In a fifteenth embodiment, an active cathode material of the
invention includes a lithium cobaltate and a manganate spinel, as
described above. In a preferred embodiment, the manganate spinel is
represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, wherein the
variables are as described above. Examples of the lithium
cobaltate, including preferred values, are as described above. In
this embodiment, the lithium cobaltate and the manganate spinel are
in a weight ratio of lithium cobaltate:manganate spinel between
about 0.95:0.05 to about 0.55:0.45, preferably between about
0.9:0.1 to about 0.6:0.4, more preferably between about 0.8:0.2 to
about 0.6:0.4, even more preferably between about 0.75:0.25 to
about 0.65:0.45, such as about 0.7:0.3.
[0087] In the fifteenth embodiment, preferably, the lithium
cobaltate is represented by an empirical formula of
Li.sub.x6M'.sub.(1-y6)Co.sub.(1-z6)M''.sub.z6O.sub.2 where: x6 is
greater than 0.05 and less than 1.2; y6 is greater than or equal to
0 and less than 0.1; z6 is equal to or greater than 0 and less than
0.5; M' is at least one of magnesium (Mg) and sodium (Na) and M''
is at least one member of the group consisting of manganese,
aluminum, boron, titanium, magnesium, calcium and strontium. In one
specific embodiment, the lithium cobaltate is LiCoO.sub.2 doped
with Mg and/or coated with a refractive oxide or phosphate, such as
ZrO.sub.2 or Al.sub.2(PO.sub.4).sub.3. In another specific
embodiment, the lithium cobaltate is LiCoO.sub.2 with no
modifiers.
[0088] In the fifteenth embodiment, preferably, the manganate
spinel does not have the A' modifier, i.e., y2 is equal to zero in
the formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. In a specific
embodiment, the manganate spinel includes a compound represented by
an empirical formula of Li.sub.(1+x1)Mn.sub.2O.sub.z1 where the
variables are as described above. In another specific embodiment,
the manganate spinel includes a compound represented by an
empirical formula of Li.sub.1+x7Mn.sub.2-y7O.sub.z7 where the
variables are as described above, preferably
Li.sub.1+x7Mn.sub.2-y7O.sub.4. Alternatively, the manganate spinel
includes a compound represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where y1 and
y2 are each independently greater than 0.0 and equal to or less
than 0.3, and other values are the same as described above.
[0089] In a even more preferred embodiment where the active cathode
material includes a lithium cobaltate and a manganate spinel, the
lithium cobaltate is LiCoO.sub.2 with no modifiers and the
manganate spinel does not have the A' modifier.
[0090] It is noted that the suitable cathode materials described
herein are characterized by empirical formulas that exist upon
manufacture of lithium-ion batteries in which they are
incorporated. It is understood that their specific compositions
thereafter are subject to variation pursuant to their
electrochemical reactions that occur during use (e.g., charging and
discharging).
[0091] Another aspect of the present invention is directed to a
lithium-ion battery that employs the active cathode materials of
the invention described above. Preferably, the battery has a
greater than about 2.2 Ah/cell capacity. More preferably, the
battery has a greater than about 3.0 Ah/cell capacity, such as
equal to or greater than about 3.3 Ah/cell; equal to or greater
than about 3.5 Ah/cell; equal to or greater than about 3.8 Ah/cell;
equal to or greater than about 4.0 Ah/cell; equal to or greater
than about 4.2 Ah/cell; between about 3.0 Ah/cell and about 6
Ah/cell; between about 3.3 Ah/cell and about 6 Ah/cell; between
about 3.3 Ah/cell and about 5 Ah/cell; between about 3.5 Ah/cell
and about 5 Ah/cell; between about 3.8 Ah/cell and about 5 Ah/cell;
and between about 4.0 Ah/cell and about 5 Ah/cell.
[0092] In one embodiment, the batteries of the invention include an
active cathode material including a mixture that includes: at least
one of a lithium cobaltate and a lithium nickelate; and at least
one of a manganate spinel represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 described
above and an olivine compound represented by an empirical formula
of Li.sub.(1-x2)A''.sub.x2MPO.sub.4 described above. In another
embodiment, the batteries of the invention include an active
cathode material including a mixture that includes: at least one of
a lithium cobaltate and a lithium nickelate selected from the group
consisting of LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
having an empirical formula of Li.sub.(1+x7)Mn.sub.2-y7O.sub.z7
described above. In yet another embodiment, the batteries of the
invention include an active cathode material including a mixture
that includes: a lithium nickelate selected from the group
consisting of LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3CO.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
having an empirical formula of Li.sub.(1+x7)Mn.sub.2-y7O.sub.z7
described above. The batteries each independently have a capacity
as described above, preferably greater than about 3.0 Ah/cell.
[0093] In a preferred embodiment, cell building for the batteries
of the invention utilize a larger format in terms of Ah/cell than
is currently used in the industry such as in the case for 18650
cells.
[0094] FIG. 1 shows a cylindrical shape lithium-ion battery (10),
which includes a positive electrode (1), coated onto an aluminum
foil, a negative electrode (2), coated onto a copper foil, a
separator positioned between the positive and negative electrodes
(3), a can containing the wound components (4), an electrically
insulated (5a) (from can) top that is crimped onto the can (5b)
(top may contain a current-interrupt-device CID, and a vent (5c)),
nickel lead that is electrically connecting the anode with the top,
and an aluminum lead that is electrically connecting the cathode
with the can (6). A PTC switch (7) can be located inside or outside
the can. Insulators are also located at the top (8) and the bottom
(9) of the can that keep foils from touching each other and
insulates foil ends from can.
[0095] The negative active material (anode) can include any
material allowing lithium to be inserted in or removed from the
material. Examples of such materials include carbonaceous
materials, for example, non-graphitic carbon, artificial carbon,
artificial graphite, natural graphite, pyrolytic carbons, cokes
such as pitch coke, needle coke, petroleum coke, graphite, vitreous
carbons, or a heat treated organic polymer compound obtained by
carbonizing phenol resins, furan resins, or similar, carbon fibers,
and activated carbon. Further, metallic lithium, lithium alloys,
and an alloy or compound thereof are usable as the negative active
materials. In particular, the metal element or semiconductor
element allowed to form an alloy or compound with lithium may be a
group IV metal element or semiconductor element, such as but not
limited to, silicon or tin. In particular amorphous tin, that is
doped with a transition metal, such as cobalt or iron/nickel, is a
metal that has high promise for anode material in these type
batteries. Oxides allowing lithium to be inserted in or removed
from the oxide at a relatively low potential, such as iron oxide,
ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide,
and tin oxide, and nitrides can be similarly usable as the negative
active materials.
[0096] The positive electrode of the batteries or cells of the
invention include the active cathode materials of the invention
described above. In particular, the batteries of the invention
employ the active cathode materials including two or more
advantages of: high specific capacity of the lithium nickelates
(e.g., Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2 or
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2) or lithium cobaltates
(e.g., LiCoO.sub.2); relatively high safety of the olivine
compounds (e.g., LiFePO.sub.4) or manganate spinels (e.g.,
Li.sub.1+x1Mn.sub.2O.sub.4 or LiMn.sub.2O.sub.4). When the active
cathode materials of the invention are used in a positive electrode
structure for use in the lithium batteries of the invention, the
resulting batteries are sufficiently safe and have high capacity in
terms of Wh/kg and/or Wh/L. The cells of the invention typically
have a form factor that is larger (e.g., 183665 form factor), both
in terms of absolute volume and Ah/cell, compared to currently
available 18650 cells. The increased cell size and capacity are
made possible at least partly by the relatively higher safety of
the mixed cathode. The cells of the invention for lithium batteries
can have safer properties than corresponding cells utilizing solely
LiCoO.sub.2 as the cathode material, although the cells have
similar or higher capacities.
[0097] Since each one of the cathode components in the mixture has
unique chemistry, it is particularly important to have an
electrolyte that has additives suitable for SET formation of each
chemical. For instance, a suitable electrolyte for batteries having
cathodes containing manganate spinel and lithium cobaltate and
anodes containing graphite may contain one or more additives of
LiBOB (lithium bis(oxalato)borate), BP (biphenyl), PS (propylene
sulfite), and VC (vinyl carbonate), which are suitable for these
types of compounds.
[0098] Examples of the non-aqueous electrolytes include a
non-aqueous electrolytic solution prepared by dissolving an
electrolyte salt in a non-aqueous solvent, a solid electrolyte
(inorganic electrolyte or polymer electrolyte containing an
electrolyte salt), and a solid or gel-like electrolyte prepared by
mixing or dissolving an electrolyte in a polymer compound or the
like.
[0099] The non-aqueous electrolytic solution is prepared by
dissolving a salt in an organic solvent. The organic solvent can
include any suitable type that has been generally used for
batteries of this type. Examples of such organic solvents include
propylene carbonate (PC), ethylene carbonate (EC), diethyl
carbonate (DEC), dimethyl carbonate (DMC), 1,2-dimethoxyethane,
1,2-diethoxyethane, .gamma.-butyrolactone, tetrahydrofuran,
2-methyl tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane,
diethyl ether, sulfolane, methylsulfolane, acetonitrile,
propionitrile, anisole, acetate, butyrate, propionate and the like.
It is preferred to use cyclic carbonates such as propylene
carbonate, or chain carbonates such as dimethyl carbonate and
diethyl carbonate. These organic solvents can be used singly or in
a combination of two types or more.
[0100] Additives or stabilizers may also be present in the
electrolyte, such as VC (vinyl carbonate), VEC (vinyl ethylene
carbonate), EA (ethylene acetate), TPP (triphenylphosphate),
phosphazenes, LiBOB (lithium bis(oxalato)borate), LiBETI, LiTFSI,
BP (biphenyl), PS (propylene sulfite), ES (ethylene sulfite), AMC
(allylmethylcarbonate), and APV (divinyladipate). These additives
are used as anode and cathode stabilizers or flame retardants,
which may make a battery have higher performance in terms of
formation, cycle efficiency, safety and life. Since each one of the
cathode components in the mixture has unique chemistries it is
particularly important to have an electrolyte that has additives
suitable for SEI formation of each chemical. For instance a
suitable electrolyte for a Li-ion battery having a spinel and
cobaltate mixed cathode and a graphite anode may contain additives
of LiBOB, PS and VC stabilizers, which respectively are suitable
for the individual compounds' SEI formations. The additives can be
added into the electrolytes in any suitable amount known in the
art, for example, between about 4 wt % and about 6 wt % of BP
(e.g., about 5.5. wt %), about 1 wt % of VC, and/or about 0.5 wt %
of PS.
[0101] The solid electrolyte can include an inorganic electrolyte,
a polymer electrolyte and the like insofar as the material has
lithium-ion conductivity. The inorganic electrolyte can include,
for example, lithium nitride, lithium iodide and the like. The
polymer electrolyte is composed of an electrolyte salt and a
polymer compound in which the electrolyte salt is dissolved.
Examples of the polymer compounds used for the polymer electrolyte
include ether-based polymers such as polyethylene oxide and
cross-linked polyethylene oxide, polymethacrylate ester-based
polymers, acrylate-based polymers and the like. These polymers may
be used singly, or in the form of a mixture or a copolymer of two
kinds or more.
[0102] A matrix of the gel electrolyte may be any polymer insofar
as the polymer is gelated by absorbing the above-described
non-aqueous electrolytic solution. Examples of the polymers used
for the gel electrolyte include fluorocarbon polymers such as
polyvinylidene fluoride (PVDF),
polyvinylidene-co-hexafluoropropylene (PVDF-HFP) and the like.
[0103] Examples of the polymers used for the gel electrolyte also
include polyacrylonitrile and a copolymer of polyacrylonitrile.
Examples of monomers (vinyl based monomers) used for
copolymerization include vinyl acetate, methyl methacrylate, butyl
methacylate, methyl acrylate, butyl acrylate, itaconic acid,
hydrogenated methyl acrylate, hydrogenated ethyl acrylate,
acrlyamide, vinyl chloride, vinylidene fluoride, and vinylidene
chloride. Examples of the polymers used for the gel electrolyte
further include acrylonitrile-butadiene copolymer rubber,
acrylonitrile-butadiene- -styrene copolymer resin,
acrylonitrile-chlorinated polyethylene-propylenediene-styrene
copolymer resin, acrylonitrile-vinyl chloride copolymer resin,
acrylonitrile-methacylate resin, and acrlylonitrile-acrylate
copolymer resin.
[0104] Examples of the polymers used for the gel electrolyte
include ether based polymers such as polyethylene oxide, copolymer
of polyethylene oxide, and cross-linked polyethylene oxide.
Examples of monomers used for copolymerization include
polypropylene oxide, methyl methacrylate, butyl methacylate, methyl
acrylate, butyl acrylate.
[0105] In particular, from the viewpoint of oxidation-reduction
stability, a fluorocarbon polymer is preferably used for the matrix
of the gel electrolyte.
[0106] The electrolyte salt used in the electrolyte may be any
electrolyte salt suitable for batteries of this type. Examples of
the electrolyte salts include LiClO.sub.4, LiAsF.sub.6, LiPF.sub.6,
LiBF.sub.4, LiB(C.sub.6H.sub.5).sub.4, LiB(C.sub.2O.sub.4).sub.2,
CH.sub.3SO.sub.3L.sub.1, CF.sub.3SO.sub.3Li, LiCl, LiBr and the
like.
[0107] Referring back to FIG. 1, in one embodiment of the
invention, the separator 3 separates the positive electrode 1 from
the negative electrode 2. The separator 3 can include any film-like
material having been generally used for forming separators of
non-aqueous electrolyte secondary batteries of this type, for
example, a microporous polymer film made from polypropylene,
polyethylene, or a layered combination of the two. In addition, if
a solid electrolyte or gel electrolyte is used as the electrolyte
of the battery 10, the separator 3 does not necessarily need to be
provided. A microporous separator made of glass fiber or cellulose
material can in certain cases also be used. Separator thickness is
typically between 9 and 25 .mu.m.
[0108] In one embodiment, the positive electrode is made by coating
a material that includes the active cathode material(s) of the
invention onto a metal foil, such as Al or Cu foil. Preferably, the
coating has a density of between about 3 g/cm.sup.3 and about 4.5
g/cm.sup.3, more preferably between about 3.5 g/cm.sup.3 and about
4.0 g/cm.sup.3, such as about 3.6 g/cm.sup.3. The thickness of the
coating is in a range of between about 15 .mu.m and about 80 .mu.m,
preferably between about 20 .mu.m and about 80 .mu.m, more
preferably between about and about 80 .mu.m (e.g., about 70 .mu.m).
Generally, the coating material includes about 93-96 wt % of the
active cathode material, carbon black and graphite in an amount of
about 1-3 wt %, and about 2-5 wt % of one or more additives known
in the art, such as PVDF. In one particular embodiment, the
positive electrode is produced by mixing the cathode material at
about 94 wt % together with about 3 wt % of a conductive agent
(e.g. acetylene black), and about 3 wt % of a binder (e.g., PVDF).
The mix is dispersed in a solvent (e.g., N-methyl-2-pyrrolidone
(NMP)), in order to prepare a slurry. This slurry is then applied
to both surfaces of an aluminum current collector foil, which
typically has a thickness of about 20 um, and dried at about
100-150.degree. C. The dried electrode is then calendared by a roll
press, to obtain a compressed positive electrode.
[0109] The negative electrode is typically prepared by mixing about
93 wt % of graphite as a negative active material, about 3 wt % of
conductive carbon (e.g. acetylene black), and about 4 wt % of a
binder (e.g. PVDF). The negative electrode is then prepared from
this mix in a process similar to that described above for positive
electrode except that a copper current collector foil, typically of
10-15 .mu.m thickness, is used.
[0110] The negative and positive electrodes and a separator formed
of a polymer film (e.g., polyethylene) with micro pores, of
thickness about 25 um, are laminated and spirally wound to produce
a spiral type electrode element. Preferably this roll has an oblong
shape.
[0111] One or more positive lead current carrying tabs are attached
to the positive current collector and then welded to the battery
top. A vent is also available, for example, at the top of the
battery. A negative lead, made of nickel metal, connects the
negative current collector to the bottom of the battery can.
[0112] An electrolyte containing for instance PC, EC, DMC, DEC
solvents with 1M LiPF.sub.6 and suitable additives at 0.5-3 wt. %
each, such as VC, LiBOB, PF, LiTFSI, BP, is vacuum filled in the
battery can 4 having the spirally wound "jelly roll", and the
battery is then sealed via an insulating seal gasket 8. A safety
valve 5c, current interrupt device, and a PTC device may also be
present at the battery top to enhance safety. A cylindrical
non-aqueous electrolyte lithium-ion secondary battery having an
outer diameter of 18 mm and a height of 65 mm as shown in FIG. 1 is
typical of lithium-ion cells used in the industry.
[0113] For a cell having an oblong shape as shown in FIG. 2, a
similar method as described above for a cylindrical cell of the
invention can be used except that the electrodes are prepared and
wound to form a cell having an oblong shape, for example, with a
thickness of about 17 mm or about 18 mm, a width of about 44 mm or
about 36 mm, a height of about 64 mm or about 65 mm. In some
specific embodiments, the cell (or battery) has a thickness of
about 17 mm, a width of about 44 mm and a height of about 64 mm; a
thickness of about 18 mm, a width of about 36 mm and a height of
about 65 mm; or a thickness of about 18 mm, a width of about 27 mm
and a height of about 65 mm.
[0114] The cells or batteries of the invention can be cylindrical
or prismatic (stacked or wound), preferably prismatic, and more
preferably of a prismatic shape that is oblong. Although the
present invention can use all types of prismatic cans, an oblong
can is preferred partly due to the two features described
below.
[0115] As shown in FIGS. 5(a)-5(d), the available internal volume
of an oblong shape, such as the 183665 form factor, is larger than
the volume of two 18650 cells, when comparing stacks of the same
external volume. In particular, FIGS. 5(a)-(b) show a comparison of
an oblong cross section (FIG. 5(a)) to a cylindrical cross section
for two 18650 cells (FIG. 5(b)). The additional useable space is
12%. When assembled into a battery pack, the oblong cell fully
utilizes more of the space that is occupied by the battery pack.
This enables novel design changes to the internal cell components
that can increase key performance features without sacrificing cell
capacity relative to that found in the industry today. Design
features such as mixing in components of higher safety, but
relatively lower capacity, while still realizing high capacity on
the pack level is therefore available. In addition, again due to
the larger available volume, one can elect to use thinner
electrodes which have relatively higher cycle life. The thinner
electrodes also have higher rate capability. Furthermore, a
prismatic cell casing (e.g., an oblong-shaped cell casing) has
larger flexibility. For instance, an oblong shape can flex more at
the waist point compared to a cylindrically shaped can, which
allows less flexibility as stack pressure is increasing upon
charging. The increased flexibility decreases mechanical fatigue on
the electrodes, which in turn causes higher cycle life. Also,
separator pore clogging is improved by the relatively lower stack
pressure.
[0116] A particularly desired feature, allowing relatively higher
safety, is available for the oblong shaped can compared to the
prismatic can whose cross-section is illustrated in FIG. 5(c). The
oblong shape provides a snug fit to the jelly roll, which minimizes
the amount of electrolyte necessary for the battery. The relatively
lower amount of electrolyte results in less available reactive
material during a misuse scenario and hence higher safety. In
addition, cost is lower due to a lower amount of electrolyte. In
the case of a prismatic can with a stacked electrode structure,
whose cross-section is illustrated in FIG. 5(d), full volume
utilization is possible without unnecessary electrolyte, but this
type of can design is more difficult and hence more costly from a
manufacturing point-of-view.
[0117] With the prismatic cells (or batteries) of the invention,
particularly with the oblong-shaped cells (or batteries) of the
invention, relatively long cycle life can be achieved partly due to
the cell's ability to expand and contract during lithium transfers
between the anode and cathode of the cell.
[0118] In another aspect, the present invention is directed to a
battery pack including one or more cells as described above for the
lithium-ion batteries of the invention.
[0119] In a preferred embodiment, the battery pack includes a
plurality of cells and each of the cells includes an active cathode
material described above. Cells of a battery packs of the invention
are connected with each other in series or parallel, or in series
and in parallel (e.g., packs having 2 cells in parallel and 3 cells
in series, a so-called 2p3s configuration). Preferably, at least
one cell of the cells included in the battery pack has a capacity
greater than about 3.0 Ah/cell, more preferably greater than about
4.0 Ah/cell. In a specific embodiment, each cell of the battery
pack of the invention includes an active cathode material including
a mixture that includes: at least one of a lithium cobaltate and a
lithium nickelate, as described above; and at least one of a
manganate spinel represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 described
above and an olivine compound represented by an empirical formula
of Li.sub.(1-x2)A''.sub.x2MPO.sub.4 described above. In another
specific embodiment, each cell of the battery pack includes a
cathode mixture that includes: at least one of a lithium cobaltate
and a lithium nickelate selected from the group consisting of
LiCoO.sub.2-coated LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
having an empirical formula of Li.sub.(1+x7)Mn.sub.2-y7O.sub.z7 as
described above. In this specific embodiment, at least one cell of
the battery pack has a capacity greater than about 3.0 Ah/cell. In
yet another specific embodiment, each cell of the battery pack
includes a cathode mixture that includes: a lithium nickelate
selected from the group consisting of LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2, and
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2; and a manganate spinel
having an empirical formula of Li.sub.(1+x7)Mn.sub.2-y7O.sub.z7 as
described above. In yet another specific embodiment, each cell of
the battery pack includes a cathode mixture that includes a lithium
cobaltate as described above and a manganate spinel a manganate
spinel represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 described
above. The lithium cobaltate and the manganate spinel are in a
weight ratio of lithium cobaltate:manganate spinel between about
0.95:0.05 to about 0.55:0.45.
[0120] In a more preferred embodiment, the battery pack includes a
plurality of cells, and the cells of a battery pack of the
invention are connected only in series and no cells are connected
in parallel. Such a configuration is demonstrated schematically in
FIG. 3 and FIG. 4. The non-parallel feature of the pack allows less
expensive individual control and monitoring of each cell in the
pack, without having to incorporate extra circuitry for detection
of individual cell parameters for cells connected in parallel,
which is costly and cumbersome due to incorporation of extra
algorithms in software and probe terminals.
[0121] FIG. 3 shows one embodiment of the invention showing three
cells of the invention connected in series. These cells, due to
their safer performance characteristics, can be made larger
compared to cells employing LiCoO.sub.2 as the choice of cathode
active material. This allows connecting cells into packs, having
fewer cells connected in parallel.
[0122] FIG. 4 shows a top, see-through view of battery pack 30 of
the invention where three cells 32 of the invention are connected
in series with each other.
[0123] In one specific embodiment, the battery packs of the
invention have a 2p3s configuration where cells are assembled in
packs having 2 cells in parallel and 3 cells in series, as can be
seen in the conventional 18650 type cells typically used for laptop
markets currently. In other embodiments, the battery packs of the
invention have 3s or 4s configurations, taking advantage of the
larger cell capacity enabled by the invention to simplify, and
therefore lower cost and improve safety, the resulting battery
pack.
[0124] Preferably, the cells included in the battery pack have
oblong-shaped can 20 as shown generally in FIG. 2. The preference
for this shape is illustrated in FIG. 5 and includes full volume
utilization, no unnecessary electrolyte inside the cell can, and
relative ease of manufacturing. The capacity of the cells in the
battery pack is typically equal to or greater than about 3.3 Ah.
The internal impedance of the cells is preferably less than about
50 milliohms, more preferably less than 30 milliohms.
[0125] A new battery design of the invention described above can
use a larger cell sizes and can potentially replace two parallel
18650 cells (2p block). An advantage of using this configuration is
that control electronics can monitor only one cell in the block
instead of two, which is the case for a 2p block of 18650 cells.
This type of monitoring can allow detection of defects, such as
shorts, in the cells, errors that may not be detected for a block
having one defect and one non-defect cell. In addition, cost
advantages can be realized by using relatively less battery
components such as PTC and CID devices and electronic wiring, which
connects cells in parallel and to control circuitry, per battery
pack.
[0126] In order to raise capacity in 18650 cells, companies such as
Sony, Sanyo, MBI (Panasonic), LG, and Samsung have been gradually
increasing the packing level of active material (graphite and
cobaltate) in the cell since their implementation in the early
90's. The higher degree of packing has in part been accomplished by
increasing electrode dimensions in terms of electrode width,
increased densification of electrodes, increased thickness of the
electrodes, less tolerance on the overcapacity of the anode
capacity/cathode capacity ratio, and a tighter fit of the jelly
roll in the battery steel can. However, one drawback of these
approaches has been less safety as seen by an increased level of
safety incidents in the field lately. Another drawback is a
decreased cycle life. Also, a typical 18650 cell can is made by
steel. As capacity of this type cell has increased, so has the
density and thickness of electrodes, along with the degree of
packing of the jelly roll in the can. The graphite and metal oxide
particulates in the anode and cathode electrodes of the 18650 cell
continuously change their dimensions as lithium is intercalated and
de-intercalated upon charging and discharging. Many metal oxide
materials increase their size, due to increase in lattice
parameters, when lithium is removed from the structure. LiCoO.sub.2
and LiNiO.sub.2 are two examples of cathode materials that increase
their c-axis when lithium is gradually removed from the structure.
Similarly, when lithium is inserted into graphite the c-axis
lattice parameter is increased. This means that upon charging, a
battery containing LiCoO.sub.2- and graphite-based electrodes, both
the anode and the cathode electrodes increase their thickness. This
generally leads to an increased stack pressure in the cell, as the
steel can limit expansion. Two typical types of degradation in the
cylindrical, conventional LiCoO.sub.2-based lithium cells are
believed to be: (1) increased stack pressure imposed by the sturdy
cylindrical steel can causes electrodes to clog the separator
pores, and (2) mechanical fatigue of relatively thick electrodes
causes the electrodes to degrade earlier due to poor connectivity
leading to decreased electronic conductivity.
[0127] On the other hand, the invention described herein realizes
that combinations of electrode materials for the cathode having two
or more active material components, one having high capacity, the
other having a relatively higher safety, can allow for lithium-ion
batteries of high safety while at the same time achieving high
capacity in battery packs employing those cells, in particular
oblong-shaped cells. In addition, not only are the cells safe
enough and of high enough capacity for commercialization
objectives, but they also exhibit significantly high cycle life.
For example, oblong-shaped cells having an external dimension of
about 64 mm in height, about 36 mm in width and about 18 mm in
thickness (see Example 4) showed higher voltage, better cycle life
and better rate capability than commercially available 18650 cells
from LG and SANYO (see Example 6). Lager cells having superior
cycle life, high safety, and high capacity can also be made by
utilizing the present invention. Even for powercells, it is
believed that the present invention can replace power cells of
18650-type or 26 mm diameter in the art. Also HEY-type batteries
can benefit from the present invention.
[0128] In yet another aspect, the present invention also includes a
system that includes a portable electronic device and a cell or
battery (e.g., lithium-ion battery), and battery pack as described
above. Examples of the portable electronic devices include portable
computers, power tools, toys, portable phones, camcorders, PDAs and
hybrid-electric vehicles. In one embodiment, the system includes a
battery pack of the invention. Features of the battery pack are as
described above.
[0129] The invention is illustrated by the following examples which
are not intended to be limiting in any way.
EXEMPLIFICATION
Example 1-3 and a Comparative Example
[0130] Using known active cathode material performance properties
that include discharge capacity, average discharge voltage, first
discharge vs. first charge efficiency, and material density,
performance features can be compared for batteries resulting from
mixtures of cathode materials. For a lithium-ion battery as
described above, a cathode is used that consists of a mixture of
active cathode materials that includes lithium cobaltate (x %),
manganate spinel (y %), and lithium nickelate (z %). The manganate
spinel and lithium nickelate cathode materials are of the preferred
type mentioned in the descriptive text above. Performance features
for these cathode materials are representative of individual
cathode materials in their representative class and for capacity,
average discharge voltage, first cycle efficiency, and density are:
lithium cobaltate--145 mAh/g, 3.70 V, 96.0%, 4.9 g/cm.sup.3;
manganate spinel--115 mAh/g, 3.80 V, 94.0%, 4.1 g/cm.sup.3; lithium
nickelate--180 mAh/g, 3.50 V, 92.0%, 4.6 g/cm.sup.3. For the case
when x=40, y=60, and z=0, the resulting active cathode material of
this example has the properties of 127 mAh/g, 3.75 V, 94.8%, and
4.4 g/cm.sup.3.
[0131] Designing a fixed capacity 5 Ah lithium-ion cell and
allowing the weight of the battery to vary in order that the
capacity requirement is achieved, allows calculation of key battery
performance and cost features for comparison under different
cathode scenarios. Additional key parameters that must be fixed in
the battery design include cell cross-sectional area (4.4.times.6.4
cm), cell thickness (1.85 cm), cathode coating area (2079
cm.sup.2), cathode electrode area (2.times.1099 cm.sup.2), anode
coating area (2181 cm.sup.2), anode electrode area (2.times.1127
cm.sup.2), separator area (2416 cm.sup.2), Al case thickness (500
pan) and density (3.70 g/cm.sup.3), coated cathode formulation (94%
active material, 3% conductive carbon, 3% binder), cathode
conductive carbon material density (1.50 g/cm.sup.3), cathode
binder material density (1.80 g/cm.sup.3), cathode porosity (20%),
cathode Al foil thickness (15 .mu.m) and density (2.70 g/cm.sup.3),
coated anode formulation (93% active material, 2% conductive
carbon, 5% binder), anode active material capacity (330 mAh/g) and
density (2.20 g/cm.sup.3), anode first discharge vs. first charge
efficiency (93%), anode conductive carbon material density (1.50
g/cm.sup.3), anode binder material density (1.80 g/cm.sup.3), anode
porosity (30%), Cu anode foil thickness (12 .mu.m) and density
(8.90 g/cm.sup.3), anode/cathode capacity ratio (1.1), separator
thickness (25 .mu.m) and porosity (45%), electrolyte density (1.20
g/cm.sup.3), cell insulator and tab weight (1.00 g), coating
solvent identity (NMP) and fraction (60% by volume), and associated
material cost parameters.
[0132] The lithium-ion battery resulting from use of the cathode
material described in this example has properties as shown in Table
2.
TABLE-US-00002 TABLE 2 Energy Cell Material Density Cost Cost for
Pack Advantage Cathode Material (Wh/L) ($/Wh) of 3 Cells ($) vs.
LiCoO.sub.2 Example 1 407 0.176 13.76 Energy (x = 40, y = 60,
Density, Cost, z = 0) Safety Example 2 406 0.162 12.64 Energy (x =
15, y = 15, Density, Cost, z = 70) Safety Example 3 404 0.166 12.85
Energy (x = 20, y = 60, Density, Cost, z = 20) Safety Comparative
401 0.208 15.97 Example 1 (x = 100)
Example 4
An Oblong Cell with High Capacity Having an Active Cathode Material
including LiCoO.sub.2/LiMn.sub.2O.sub.4
[0133] 94 wt. % mixed cathode with a weight ratio of 70:30 for
LiCoO.sub.2:LiMn.sub.2O.sub.4, 3 wt. % of carbon black and 3 wt. %
of PVDF were mixed in NMP under stirring. The electrode slurry was
coated onto a 15 micrometer thick Al current collector. The Al
current collector had a dimension of width of 56 mm and length of
1568 mm. The slurry was coated on both sides of the Al current
collector. The coating length was 1510 and 1430 mm for side 1 and
side 2. The process media NMP was removed by heating the coated
electrode at 150.degree. C. for a few minutes. The electrode was
pressed to control the coated density. The 2-side coating was
identical in every aspect. The thickness of the total electrode was
140 micrometers. The composite cathode density was 3.6 glee. Two Al
tabs with about a width of 3 mm, length of 55 mm and thickness of
0.2 mm were welded onto the uncoated Al current collector.
[0134] 93 wt. % of graphite, 2 wt. % of carbon black and 5 wt. % of
PVDF binder were mixed in NMP under stirring. The electrode slurry
was coated onto a 12 micrometer thick Cu current collector. The Cu
current collector had a dimension of width of 57.5 mm and length of
1575 mm. The slurry was coated on both sides of the Cu current
collector. The coating length was 1495 and 1465 mm for side 1 and
side 2 respectively. The process media NMP was removed by heating
the coated electrode at 150.degree. C. for a few minutes. The
electrode was pressed to control the coated density. The 2-side
coating was identical in every aspect. The thickness of the total
electrode was 130 micrometers. The composite anode density was 1.8
g/cc. Two Ni tabs with about a width of 3 mm, length of 55 mm and
thickness of 0.2 mm was welded onto the uncoated Cu current
collector.
[0135] The cathode and anode were separated by a microporous
separator, with a thickness of 25 micrometers, width of 60 mm and
length of 310 cm. They were wounded into a jelly-roll. The
jelly-roll was pressed into a prismatic format.
[0136] The pressed jelly-roll was inserted into a prismatic Al
case, with Al thickness of 0.4 mm. The case had an external
dimension of about 64 mm in height, 36 mm in width and 18 mm in
thickness. The positive tab was welded on to the top Al cap, and
the negative tab was welded onto a connection passing through the
Al case. An Al cap was welded onto the Al case. Approximately 10 g
1M LiPF.sub.6 EC/PC/EMC/DMC electrolyte solution was added into the
cell under vacuum. After formation, the cell was completely
sealed.
[0137] This cell had a capacity of 4.4 Ah at C/5 discharge rate.
The nominal voltage was 3.7 V. The total cell weight was
approximately 89 g. The cell energy density was approximately 183
Wh/kg and 440 Wh/liter.
Example 5A (Prophetic Example)
A Cell with an Active Cathode Material Including
LiCoO.sub.2/LiMn.sub.1.9Al.sub.0.1O.sub.4
[0138] In this example, a prismatic cell with an active cathode
material including LiCoO.sub.2/LiMn.sub.1.9Al.sub.0.1O.sub.4 is
designed. This cell can be made by a similar procedure as described
above in Example 4. For this example, the cathode mix includes 94
wt. % of mixed cathode with a weight ratio of 70:30 for
LiCoO.sub.2:LiMn.sub.1.9Al.sub.0.1O.sub.4, 3 wt. % of carbon black
and 3 wt. % of PVDF. The electrode slurry is coated onto a 15
micrometer thick Al current collector. The Al current collector has
a dimension of width of 56 mm and length of 1913 mm. The slurry is
coated on both sides of the Al current collector. The coating
length is 1913 and 1799 mm for side 1 and side 2. The process media
NMP is removed by heating the coated electrode at 150.degree. C.
for a few minutes. The electrode is pressed to control the porosity
of 25% volume. The 2-side coating is identical in every aspect. The
thickness of the single coating layer is 50 micrometers. The
composite cathode density is 3.36 glee. An Al tab with a width of 5
mm, length of 64 mm and thickness of 0.1 mm is welded onto the
uncoated Al current collector.
[0139] 93 wt. % of graphite, 2 wt. % of carbon black and 5 wt. % of
PVDF binder is mixed in NMP under stirring. The electrode slurry is
coated onto a 12 micrometer thick Cu current collector. The Cu
current collector has a dimension of width of 58 mm and length of
1940 mm. The slurry is coated on both sides of the Cu current
collector. The coating length is 1903 and 1857 mm for side 1 and
side 2 respectively, leaving 10 mm Cu uncoated. The process media
NMP is removed by heat the coated electrode at 150.degree. C. for a
few minutes. The electrode is pressed to control the porosity of
37% volume. The 2-side coating is identical in every aspect. And
the thickness of the single coating layer is 53 micrometers. The
calculated composite anode density is 1.35 g/cc, A Ni tab with a
width of 5 mm, length of 64 mm and thickness of 0.5 mm can be
welded onto the uncoated Cu current collector.
[0140] The cathode and anode are separated by a microporous
separator, with a thickness of 25 micrometers, width of 60 mm and
length of 4026 mm. They are then wounded into a jelly-roll. The
jelly-roll is pressed into a prismatic format.
[0141] The pressed jelly-roll is inserted into a rectangular Al
case, with Al thickness of 0.5 mm. The case has an external
dimension of 64 mm in height, 44 mm in width and 17 mm in
thickness. The positive tab is welded on to the top Al cap, and the
negative tab is welded onto the Al case. An Al cap is welded onto
the Al case. Approximately 12.3 g 1M LiPF.sub.6 EC/EMC/DMC
electrolyte solution is added into the cell under vacuum. After
formation, the cell is completely sealed.
[0142] This cell has a calculated capacity of 4.5 Ah at C/5
discharge rate. The calculated nominal voltage is 3.7V. The total
calculated cell weight is approximately 96 g. The calculated cell
energy density is approximately 174 Wh/kg and 350 Wh/L.
Example 5B (Prophetic Example)
A Cell with an Active Cathode Material Including
LiCoO.sub.2/LiMn.sub.1.9Al.sub.0.1O.sub.4/LiNi.sub.0.8Al.sub.0.05CO.sub.0-
.15O.sub.2
[0143] In this example, a prismatic cell with an active cathode
material including
LiCoO.sub.2/LiMn.sub.1.9Al.sub.0.1O.sub.4/LiNi.sub.0.8Al.sub.0.-
05Co.sub.0.15O.sub.2 is designed. This cell can be made by a
similar procedure as described above in Example 4.
[0144] 94 wt. % of mixed cathode with a weight ratio of 10:50:40
for
LiCoO.sub.2:LiMn.sub.1.9Al.sub.0.1O.sub.4:LiNi.sub.0.8Al.sub.0.05Co.sub.0-
.15O.sub.2, 3 wt. % of carbon black and 3 wt. % of PVDF are mixed
in NMP under stirring. The electrode slurry is coated onto a 15
micrometer thick Al current collector. The Al current collector has
a dimension of width of 56 mm and length of 1913 mm. The slurry is
coated on both sides of the Al current collector. The coating
length is 1913 and 1799 mm for side 1 and side 2. The process media
NMP is removed by heat the coated electrode at 150.degree. C. for a
few minutes. The electrode is pressed to control the porosity of
25% volume. The 2-side coating is identical in every aspect. And
the thickness of the single coating layer is 56 micrometers. The
calculated composite cathode density is 3.2 g/cc. An Al tab with a
width of 5 mm, length of 64 mm and thickness of 0.1 mm is welded
onto the uncoated Al current collector.
[0145] 93 wt. % of graphite, 2 wt. % of carbon black and 5 wt. % of
PVDF binder are mixed in NMP under stirring. The electrode slurry
is coated onto a 12 micrometer thick Cu current collector. The Cu
current collector has a dimension of width of 58 mm and length of
1940 mm. The slurry is coated on both sides of the Cu current
collector. The coating length is 1903 and 1857 mm for side 1 and
side 2 respectively, leaving 10 mm Cu uncoated. The process media
NMP is removed by heat the coated electrode at 150.degree. C. for a
few minutes. The electrode is pressed to control the porosity of
37% volume. The 2-side coating is identical in every aspect. The
thickness of the single coating layer is 60 micrometers. The
calculated composite anode density is 1.35 g/cc. A Ni tab with a
width of 5 mm, length of 64 mm and thickness of 0.5 mm is welded
onto the uncoated Cu current collector.
[0146] The cathode and anode are separated by a microporous
separator, with a thickness of 25 micrometers, width of 60 mm and
length of 4026 mm. They are wounded into a jelly-roll. The
jelly-roil is then pressed into a prismatic format.
[0147] The pressed jelly-roll is inserted into a rectangular Al
case, with Al thickness of 0.5 mm. The case has an external
dimension of 64 mm in height, 44 mm in width and 17 mm in
thickness. The positive tab is welded on to the top Al cap, and the
negative tab is welded onto the Al case. An Al cap is welded onto
the Al case. Approximately 12.3 g 1M LiPF.sub.6 EC/EMC/DMC
electrolyte solution is added into the cell under vacuum. After
formation, the cell is completely sealed.
[0148] This cell has a calculated capacity of 5 Ah at C/5 discharge
rate. The calculated nominal voltage is 3.67V. The total calculated
cell weight is approximately 101 g. The calculated cell energy
density is approximately 181 Wh/kg and 362 Wh/L.
Example 6
Cell Tests
[0149] The cell of Example 4 was cycled (i.e. charged and
discharged) as follows:
[0150] The cell was charged with a constant current of 0.7C to a
voltage of 4.2 V and then was charged using a constant voltage of
4.2 V. The constant voltage charging was ended when the current
reached 44 mA. After resting at the open circuit state for 30
minutes, it was discharged with a constant current of C/5. The
discharge ended when the cell voltage reached 2.75 V. These
procedures were repeated for 3 times.
[0151] Then the cell was charged with a constant current of 0.7C to
a voltage of 4.2 V and then subsequently was charged using a
constant voltage of 4.2 V. The constant voltage charging was ended
when the current reached 44 mA. After resting at the open circuit
state for 30 minutes, it was discharged with a constant current of
1C. The discharge ended when the cell voltage reached 2.75 V. These
procedures repeated continuously to obtain cycle life data.
[0152] For rate capability testing, eight cells were charged as
described about and discharge was performed to 2.75 V using
different current rates ranging in value from C/5 to 2C.
[0153] As a comparison example, an LG 18650 of LG in Seoul, Korea
("LG") and a SANYO 18650 cell were tested with the procedures
described above. Cells were typically tested at 23.degree. C. (room
temperature) and 60.degree. C. Results of the cell tests were shown
in FIGS. 6-9. As can be seen in FIGS. 6-9, a cell of the present
invention showed higher voltage (FIG. 6), better cycle life at room
temperature (FIG. 7), better cycle life at 60.degree. C., (FIG. 8)
and better rate capability (FIG. 9).
Example 7
Safety Tests for Lithium-Ion Batteries Including a Mixture of
Lithium Cobaltate and Manganate Spinel
[0154] The safety of a lithium-ion battery, consisting of a single
or multiple cells, is generally dependent on the chemistry internal
to the lithium-ion cell(s). In all cases, a lithium-ion cell will
contain materials with some given amount of energy, that energy
being capable of release through certain abuse scenarios that may
cause fire or explosion from the cell. Typically, lithium-ion cells
are designed for acceptable safety performance through one or more
of the followings: (1) careful selection of materials, (2) proper
engineering design of internal cell chemicals and components, (3)
incorporation of safety devices into the cell, and (4) control
electronics (i.e. pack electronics, software control) that maintain
safe operation of cell(s). In addition, preferably, manufacturing
environment is carefully controlled to avoid defects and foreign
particulates that may cause internal shorts, which can initiate
rapid heating and thermal runaway.
[0155] Preferably, the lithium-ion cells (batteries) of the
invention are designed to withstand abuse scenarios that might be
encountered during their use. One reference for the abuse scenarios
is the UL safety testing protocols for lithium-ion cells, UL1642.
General categories of abuse include mechanical abuse, electronic
abuse and temperature abuse.
DSC Tests
[0156] DSC tests were run on cathode mixtures that included
LiCoO.sub.2 and Li.sub.1.1Mn.sub.1.96 Mg.sub.0.03O.sub.4. DSC tests
were also run on the individual cathode materials. For the DSC
testing, the cathodes were prepared by mixing LiCoO.sub.2,
Li.sub.1.1Mn.sub.1.96Mg.sub.0.03O.sub.4 (in the designed ratios),
carbon black and polyvinylidene fluoride (93:3.5:3.5, w:w:w) in
n-methyl-2-pyrrolidone. The slurry was then cast on aluminum foil
and dried at 110.degree. C. for overnight. And the coated electrode
was then calendared to the controlled thickness with a target
loading density of 3.3 to 3.7 g/cc depending on the ratio of
LiCoO.sub.2 to the manganate spinel to ensure the same porosity for
all the electrodes. Disks were then punched out of the foil.
Lithium foil was used as an anode. The electrolyte was 1M LiPF6 in
a mixture of EC, PC and DEC. The coin cells made were tested at C/5
for two cycles between 3.0 V and 4.3 V, then fully charged to 4.3V
before DSC study. The cells were then opened in an Ar-filled glove
box. The electrode materials were recovered from the aluminum foil
and sealed into a gold plated stainless steel pan. The measurements
were carried out using a temperature scan rate of 5.degree.
C./min.
[0157] FIG. 10 shows the total heat of reaction for different
cathode material samples (diamonds in FIG. 10) where the amount of
the manganate spinel material was varied from 0 to 100%. This data
was a measure of the chemical safety of a Li-ion cell, with lower
total heat indicating increased safety. Also plotted in FIG. 10 is
a theoretical prediction for the total heat based on a simple
combination of the pure materials (open circles in FIG. 10). As
shown in FIG. 10, the actual measured values showed unexpected
enhanced improvement over the predicted value in the safety of the
cells.
Rate of Heat Release Tests
[0158] Another measure of safety is generally the rate at which the
available energy can be released. For two cathode samples with
similar amounts of energy, the sample that releases heat at a
slower rate would be expected to be safer. FIG. 11 shows data for a
range of cathode samples with varying the amount of
Li.sub.1.1Mn.sub.1.96Mg.sub.0.03O.sub.4. Based on this data, there
appears to be an optimum range for safety based on maximum rate of
reaction. The data shown in FIG. 11 suggested that a mixture of
approximately 20-50% of Li.sub.1.1Mn.sub.1.96Mg.sub.0.03O.sub.4 and
80-50% of LiCoO.sub.2 was optimal.
[0159] FIG. 12 shows data for different cathode materials used in
full-sized Li-ion cells. The cathode materials included an undoped
manganate spinel (Li.sub.1+x1Mn.sub.2O.sub.4) and LiCoO.sub.2. The
amount of an undoped manganate spinel (Li.sub.1+x1Mn.sub.2O.sub.4)
was varied from 0-50%. Based on a temperature environment test of
subjecting the cell to 150.degree. C., a test that typically would
result in fire/explosion of Li-ion cells, the time at 150.degree.
C. before fire/explosion was measured. The data of FIG. 12
indicates an advantage associated with the cathode sample
containing from 20-50% of the manganate spinel. In these cases, the
cells were able to withstand the high temperature treatment for
longer time, indicating increased chemical stability.
Cell Temperature During Discharge
[0160] Under high loading conditions, the temperature of Li-ion
cells will generally increase significantly. The maximum
temperature is typically related to the cell chemistry, and
engineering of the cells. As shown in Table 3, the maximum
temperatures measured at the surface of cells of the invention,
which included 70% LiCoO.sub.2 and 30% of
Li.sub.1+x1Mn.sub.2O.sub.4 as the cathode materials of the cells,
under different discharge rate were lower than the comparable cells
with cathode of pure LiCoO.sub.2 from SANYO, Japan.
TABLE-US-00003 TABLE 3 Maximum Temperature (.degree. C.) at
Discharge Rates from C/5 (1/5 of a cycle) to 2C (2 cycles) C/5 C/3
C/2 1C 2C Invention 25.0 27.6 28.7 36.3 49.7 Comparable cell 25.6
26.2 29.2 37.7 52.5
Example 8
Cycle Life for Lithium-Ion Batteries Including a Mixture of Lithium
Cobaltate and Manganate Spinel
[0161] One of the important performance parameters of Li-ion cells
is the capacity and the retention of the capacity (cycle life) in
the service life of the cells. The cycle life was typically
measured by the number of cycles when the cell capacity is 80% of
the initial capacity. FIG. 13 shows that the cells of the invention
with cathode of 70% LiCoO.sub.2 and 30% of
Li.sub.1+x1Mn.sub.2O.sub.4 have much longer cycle life than those
comparable, commercially available cells with cathode of pure
LiCoO.sub.2 from LG, Korea ("LG") and from SANYO, Japan
("Sanyo").
EQUIVALENTS
[0162] While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *