U.S. patent application number 11/291298 was filed with the patent office on 2006-04-20 for electrode active material and method of making the same.
Invention is credited to George W. Adamson, Jeremy Barker, Gerbrand Ceder, Ming Dong, Dane Morgan, M. Yazid Saidi.
Application Number | 20060083990 11/291298 |
Document ID | / |
Family ID | 32595316 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060083990 |
Kind Code |
A1 |
Adamson; George W. ; et
al. |
April 20, 2006 |
Electrode active material and method of making the same
Abstract
The invention provides an electrochemical cell which includes a
first electrode and a second electrode which is a counter electrode
to said first electrode, and an electrolyte material interposed
there between. The first electrode includes an alkali metal
phosphorous compound doped with an element having a valence state
greater than that of the alkali metal.
Inventors: |
Adamson; George W.;
(Henderson, NV) ; Barker; Jeremy; (Oxfordshire,
GB) ; Ceder; Gerbrand; (Cambridge, MA) ; Dong;
Ming; (Suzhou New District, CN) ; Morgan; Dane;
(Cambridge, MA) ; Saidi; M. Yazid; (Henderson,
NV) |
Correspondence
Address: |
VALENCE TECHNOLOGY, INC.
1889 E. MAULE AVENUE, SUITE A
LAS VEGAS
NV
89119
US
|
Family ID: |
32595316 |
Appl. No.: |
11/291298 |
Filed: |
December 1, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10741257 |
Dec 19, 2003 |
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11291298 |
Dec 1, 2005 |
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60435144 |
Dec 19, 2002 |
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Current U.S.
Class: |
429/231.5 ;
429/231.9; 429/231.95 |
Current CPC
Class: |
C04B 2235/3203 20130101;
H01M 4/5825 20130101; Y02E 60/10 20130101; C04B 2235/3206 20130101;
C04B 2235/3239 20130101; H01M 4/382 20130101; H01M 2300/0037
20130101; H01M 4/582 20130101; C04B 2235/3262 20130101; C04B
2235/3272 20130101; H01M 4/136 20130101; C04B 2235/3244 20130101;
C04B 2235/3251 20130101; C01P 2002/72 20130101; C04B 35/447
20130101; C04B 2235/441 20130101; C04B 2235/449 20130101; C04B
2235/3277 20130101; H01M 4/58 20130101; H01M 10/052 20130101 |
Class at
Publication: |
429/231.5 ;
429/231.9; 429/231.95 |
International
Class: |
H01M 4/58 20060101
H01M004/58 |
Claims
1. A battery, comprising: a first electrode comprising a compound
represented by the general nominal formula:
[A.sub.a,D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, wherein: (i) A
comprises at least one alkali metal, and 0<a.ltoreq.9; (ii) D is
at least one element with a valence state of .gtoreq.2+, and
0<d.ltoreq.1; (iii) M comprises at least one redox active
element, and 1.ltoreq.m.ltoreq.3; (iv) XY.sub.4 is selected from
the group consisting of X'[O.sub.4-x,Y'.sub.x],
X'[O.sub.4-y,Y'.sub.2y], X''S.sub.4,
[X.sub.z''',X'.sub.1-z]O.sub.4, and mixtures thereof, wherein: (a)
X' and X''' are each independently selected from the group
consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof; (b)
X'' is selected from the group consisting of P, As, Sb, Si, Ge, V,
and mixtures thereof; (c) Y' is selected from the group consisting
of a halogen, S, N, and mixtures thereof; and (d)
0.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.2,
0.ltoreq.z.ltoreq.1,and1.ltoreq.p.ltoreq.3; and (v) Z is selected
from the group consisting of OH, a halogen, and mixtures thereof,
and 0.ltoreq.e.ltoreq.4; wherein A, D, M, X, Y, Z, a, d, m, p, e,
x, y and z are selected so as to maintain electroneutrality of the
compound; the battery further comprising a second counter-electrode
comprising an intercalation active material; and an
electrolyte.
2. The battery of claim 1, wherein A is selected from the group
consisting of Li, K, Na, and mixtures thereof.
3. The battery of claim 1, wherein A is Li.
4. The battery of claim 1, wherein D is a transition metal.
5. The battery of claim 4, wherein D is selected from the group
consisting of Nb, Zr, Ti, Ta, Mo, and W.
6. The batter of claim 1, wherein D is selected from the group
consisting of Mg, Zr and Nb.
7. The battery of claim 1, wherein A is partially substituted by D
by isocharge substitution.
8. The battery of claim 7, wherein the compound is represented by
the general nominal formula
[A.sub.a-f,D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, wherein f=d and
0<f.ltoreq.1.
9. The battery of claim 7, wherein the compound is represented by
the general nominal formula
[A.sub.a-f,D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, wherein
f.noteq.d and 0<f.ltoreq.9.
10. The battery of claim 1, wherein A is partially substituted by D
by aliovalent substitution.
11. The battery of claim 1 0, wherein the compound is represented
by the general nominal formula [ A a - f V A , D d V D ] .times. M
m .function. ( XY 4 ) p .times. Z e , ##EQU5## wherein f=d and
0<f.ltoreq.1, V.sup.A is the oxidation state of A and V.sup.D is
the oxidation state of D.
12. The battery of claim 10, wherein the compound is represented by
the general nominal formula [ A a - f V A , D d V D ] .times. M m
.function. ( XY 4 ) p .times. Z e , ##EQU6## wherein f.noteq.d and
0<f.ltoreq.9, V.sup.A is the oxidation state of A and V.sup.D is
the oxidation state of D.
13. The battery of claim 1, wherein M is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
and Pb.sup.2+.
14. The battery of claim 1, wherein M is selected from the group
consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Co.sup.3+, Ni.sup.3+, Mo.sup.3+, and Nb.sup.3+.
15. The battery of claim 1, wherein M=MI.sub.nMII.sub.o,
0<o+n.ltoreq.3 and 0<o,n, wherein MI and MII are each
independently selected from the group consisting of redox active
elements and non-redox active elements, wherein at least one of MI
and MII is redox active.
16. The battery of claim 15, wherein MI and MII are both redox
active.
17. The battery of claim 15, wherein MI is substituted by MII by
isocharge substitution.
18. The battery of claim 17, wherein M=MI.sub.n-pMII.sub.o, and
o=p.
19. The battery of claim 17, wherein M=MI.sub.n-pMII.sub.o, and
o.noteq.p.
20. The battery of claim 17, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof, and MII is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures
thereof.
21. The battery of claim 17, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof, and MII is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, and mixtures thereof.
22. The battery of claim 17, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof, and MII is selected from the group
consisting of Zn.sup.2+, Cd.sup.2+, and mixtures thereof.
23. The battery of claim 17, wherein MI is selected from the group
consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Co.sup.3+, Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof,
and MII is selected from the group consisting of Sc.sup.3+,
Y.sup.3+, B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures
thereof.
24. The battery of claim 15, wherein MI is substituted by MII by
aliovalent substitution.
25. The battery of claim 24, wherein M=MI.sub.n-oMII.sub.o.
26. The battery of claim 24, wherein M = MI n - o V MI .times. MII
o V MII , ##EQU7## wherein V.sup.MI is the oxidation state of MI,
and V.sup.MII is the oxidation state of MII.
27. The battery of claim 26, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+,Sn.sup.2+,
Pb.sup.2+, and mixtures thereof, and MII is selected from the group
consisting of Sc.sup.3+, Y.sup.3+, B.sup.3+, Al.sup.3+, Ga.sup.3+,
In.sup.3+, and mixtures thereof.
28. The battery of claim 26, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof, and MII is selected from the group
consisting of alkali metals, Cu.sup.1+, Ag.sup.1+, and mixtures
thereof.
29. The battery of claim 26, wherein MI is selected from the group
consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Co.sup.3+, Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof,
and MII is selected from the group consisting of Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Zn.sup.2+, Cd.sup.2+,
Ge.sup.2+, and mixtures thereof.
30. The battery of claim 26, wherein MI is selected from the group
consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Co.sup.3+, Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof
MII is selected from the group consisting of alkali metals,
Cu.sup.1+, Ag.sup.1+, and mixtures thereof.
31. The battery of claim 1, wherein M=M1.sub.qM2.sub.rM3.sub.s,
wherein: (a) M1 is a redox active element with a 2+ oxidation
state; (b) M2 is selected from the group consisting of redox and
non-redox active elements with a 1 + oxidation state; (c) M3 is
selected from the group consisting of redox and non-redox active
elements with a 3+ oxidation state; and (d) at least one of p, q
and r is greater than 0, and at least one of M1, M2, and M3 is
redox active.
32. The battery of claim 31, wherein q=q-(r+s).
33. The battery of claim 31, wherein M = M .times. .times. 1 q - r
V M1 - s V M1 .times. M .times. .times. 2 r V M2 .times. M .times.
.times. 3 s V M3 , ##EQU8## wherein V.sup.MI is the oxidation state
of M1, V.sup.M2 is the oxidation state of M2, and V.sup.M3 is the
oxidation state of M3.
34. The battery of claim 33, wherein M1 is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof; M2 is selected from the group
consisting of Cu.sup.1+, Ag.sup.1+ and mixtures thereof; and M3 is
selected from the group consisting of Ti.sup.3+, V.sup.3+,
Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3, Ni.sup.3+, Mo.sup.3+,
Nb.sup.3+, and mixtures thereof.
35. The battery of claim 33, wherein MI is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof; M2 is selected from the group
consisting of Li.sup.1+, K.sup.1+, Na.sup.1+, Ru.sup.1+, Cs.sup.1+,
and mixtures thereof; and M3 is selected from the group consisting
of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+,
Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof.
36. The battery of claim 33, wherein MI is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures thereof;
M2 is selected from the group consisting of Cu.sup.1+, Ag.sup.1+
and mixtures thereof; and M3 is selected from the group consisting
of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+,
Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof.
37. The battery of claim 33, wherein Ml is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures thereof;
M2 is selected from the group consisting of Li.sup.1+, K.sup.1+,
Na.sup.1+, Ru.sup.1+, Cs.sup.1+, and mixtures thereof; and M3 is
selected from the group consisting of Ti.sup.3+, V.sup.3+,
Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+, Ni.sup.3+, Mo.sup.3+,
Nb.sup.3+, and mixtures thereof.
38. The battery of claim 33, wherein M1 is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof; M2 is selected from the group
consisting of Cu.sup.1+, Ag.sup.1+ and mixtures thereof; and M3 is
selected from the group consisting of Sc.sup.3+, Y.sup.3+,
B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures
thereof.
39. The battery of claim 33, wherein M1 is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Pb.sup.2+,
and mixtures thereof; M2 is selected from the group consisting of
Li.sup.1+, K.sup.1+, Na.sup.1+, Ru.sup.1+, Cs 1+, and mixtures
thereof; and M3 is selected from the group consisting of Sc.sup.3+,
Y.sup.3+, B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures
thereof.
40. The battery of claim 1, wherein the counter-electrode comprises
an intercalation active material selected from the group consisting
of a transition metal oxide, a metal chalcogenide, carbon, and
mixtures thereof.
41. The battery of claim 40, wherein the counter-electrode
comprises graphite.
42. A compound made by a process comprising the step of reacting at
least one A-containing compound, at least one D-containing
compound, one or more M-containing compounds, at least one
XY.sub.4-supplying or containing compound, and (optionally) one or
more Z-containing compounds, at a temperature and for a time
sufficient to form the compound; Wherein the compound is
represented by the general nominal formula:
[A.sub.a,D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, wherein: (i) A
comprises at least one alkali metal, and 0<a.ltoreq.9; (ii) D is
at least one element with a valence state of .gtoreq.2+, and
0<d.ltoreq.1; (iii) M comprises at least one redox active
element, and 1.ltoreq.m.ltoreq.3; (iv) XY.sub.4 is selected from
the group consisting of X'[O.sub.4-x,Y'.sub.x],
X'[O.sub.4-y,Y'.sub.2y], X''S.sub.4,
[X.sub.z''',X'.sub.1-z]O.sub.4, and mixtures thereof, wherein: (a)
X' and X''' are each independently selected from the group
consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof; (b)
X'' is selected from the group consisting of P, As, Sb, Si, Ge, V,
and mixtures thereof; (c) Y' is selected from the group consisting
of a halogen, S, N, and mixtures thereof; and (d)
0.ltoreq.x.ltoreq.3, 0.ltoreq.y.ltoreq.2, 0.ltoreq.z.ltoreq.1, and
1.ltoreq.p.ltoreq.3; and (v) Z is selected from the group
consisting of OH, a halogen, and mixtures thereof, and
0.ltoreq.e.ltoreq.4; wherein A, D, M, X, Y, Z, a, d, m, p, e, x, y
and z are selected so as to maintain electroneutrality of the
compound.
Description
[0001] This Application is a divisional of application Ser. No.
10/741,257, filed Dec. 19, 2003, which claims the benefit of
Application Ser. No. 60/435,144, filed Dec. 19, 2002.
FIELD OF THE INVENTION
[0002] This invention relates to improved electrode active
materials, methods for making such improved active materials, and
electrochemical cells employing such improved active materials.
BACKGROUND OF THE INVENTION
[0003] A battery consists of one or more electrochemical cells,
wherein each cell typically includes a positive electrode, a
negative electrode, and an electrolyte or other material for
facilitating movement of ionic charge carriers between the negative
electrode and positive electrode. As the cell is charged, cations
migrate from the positive electrode to the electrolyte and,
concurrently, from the electrolyte to the negative electrode.
During discharge, cations migrate from the negative electrode to
the electrolyte and, concurrently, from the electrolyte to the
positive electrode.
[0004] Such batteries generally include an electrochemically active
material having a crystal lattice structure or framework from which
ions can be extracted and subsequently reinserted, and/or permit
ions to be inserted or intercalated and subsequently extracted.
[0005] Recently, three-dimensionally structured compounds
comprising polyanions (e.g., (SO.sub.4).sup.n-, (PO.sub.4).sup.n-,
(AsO.sub.4).sup.n-, and the like), have been devised as viable
alternatives to oxide-based electrode materials such as
LiM.sub.xO.sub.y. Examples of such polyanion-based materials
include the ordered olivine LiMPO.sub.4 compounds, wherein M=Mn,
Fe, Co or the like. Other examples of such polyanion-based
materials include the NASICON Li.sub.3M.sub.2(PO.sub.4).sub.3
compounds, wherein M=Mn, Fe, Co or the like. Although these classes
of lithiated polyanion-based compounds have exhibited some promise
as electrode components, many such polyanion-based materials are
not economical to produce, afford insufficient voltage, have
insufficient charge capacity, exhibit low ionic and/or electrical
conductivity, or lose their ability to be recharged over multiple
cycles. Therefore, there is a current need for an electrode active
material that exhibits greater charge capacity, is economical to
produce, affords sufficient voltage, exhibits greater ionic and
electrical conductivity, and retains capacity over multiple
cycles.
SUMMARY OF THE INVENTION
[0006] The present invention provides novel electrode materials
represented by the general formula: [A.sub.a,
D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, wherein: [0007] (i) A is
selected from the group consisting of elements from Group I of the
Periodic Table, and mixtures thereof, and 0<a .ltoreq.9; [0008]
(ii) D is at least one element with a valence state of .gtoreq.2+,
and 0<d<1; [0009] (iii) M includes at least one redox active
element, and 1.ltoreq.m.ltoreq.3; [0010] (iv) XY.sub.4 is selected
from the group consisting of X'[O.sub.4-x,Y'.sub.x],
X'[O.sub.4-y,Y'.sub.2y], X''S.sub.4,
[X.sub.z''',X'.sub.1-z]O.sub.4, and mixtures thereof, wherein:
[0011] (a) X' and X''' are each independently selected from the
group consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof;
[0012] (b) X'' is selected from the group consisting of P, As, Sb,
Si, Ge, V, and mixtures thereof; [0013] (c) Y' is selected from the
group consisting of a halogen, S, N, and mixtures thereof; and
[0014] (d)
0.ltoreq.x.ltoreq.3,0.ltoreq.y.ltoreq.2,0.ltoreq.z.ltoreq.1,and
1.ltoreq.p.ltoreq.3; and [0015] (v) Z is OH, a halogen, or mixtures
thereof, and 0.ltoreq.e.ltoreq.4; wherein A, D, M, X, Y, Z, a, d,
m, x, y, z, p and e are selected so as to maintain
electroneutrality of the material.
[0016] This invention also provides electrodes which utilize an
electrode active material of this invention. Also provided are
batteries having a first electrode that includes the electrode
active material of this invention; a second counter-electrode
having a compatible active material; and an electrolyte interposed
there between. In a preferred embodiment, the novel electrode
active material of this invention is used as a positive electrode
(cathode) active material, reversibly cycling alkali metal ions
with a compatible negative electrode (anode) active material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows the Reitvelt refined CuK.alpha. (.lamda.=1.5405
.ANG. with a scattering angle of 2.theta.) x-ray diffraction
patterns collected for LiFePO.sub.4,
Li.sub.0.98Mg.sub.0.01FePO.sub.4, and
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 active materials.
[0018] FIG. 2 is a voltage profile of the first, third and fifth
discharge cycles for a LiCoPO.sub.4-containing cathode (100%
LiCoPO.sub.4, 0% binder, 0% carbon) cycled with a lithium metal
anode using constant current cycling at .+-.0.2 milliamps per
square centimeter (mA/cm .sup.2) in a range of 3.0 to 5 volts (V)
at a temperature of about 23.degree. C. The electrolyte includes
ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a
weight ratio of 2:1, and a 1 molar concentration of LiPF.sub.6
salt. A glass fiber separator interpenetrated by the solvent and
the salt is interposed between the cathode and the anode.
[0019] FIG. 3 is a voltage profile of the first, third and fifth
discharge cycles for a
Li.sub.0.98Mg.sub.0.05Co.sub.0.96PO.sub.4-containing cathode (100%
Li.sub.0.98Mg.sub.0.05Co.sub.0.96PO.sub.4, 0% binder, 0% carbon)
cycled in a cell using the test conditions described with respect
to FIG. 2.
[0020] FIG. 4 is a voltage profile of the first, third and fifth
discharge cycles for a LiFePO.sub.4-containing cathode (100%
LiFePO.sub.4, 0% binder, 0% carbon) cycled in a cell using the test
conditions described with respect to FIG. 2.
[0021] FIG. 5 is a voltage profile of the first, third and fifth
discharge cycles for a Li.sub.0.98Mg.sub.0.01FePO.sub.4-containing
cathode (100% Li.sub.0.98Mg.sub.0.01FePO.sub.4, 0% binder, 0%
carbon) cycled in a cell using the test conditions described with
respect to FIG. 2.
[0022] FIG. 6 is a voltage profile of the first, third and fifth
discharge cycles for a
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4-containing cathode (100%
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4, 0% binder, 0% carbon)
cycled in a cell using the test conditions described with respect
to FIG. 2.
[0023] FIG. 7 is a voltage profile of the first, third and fifth
discharge cycles for a Li.sub.0.99Nb.sub.0.002FePO.sub.4-containing
cathode (100% Li.sub.0.99Nb.sub.0.002FePO.sub.4, 0% binder, 0%
carbon) cycled in a cell using the test conditions described with
respect to FIG. 2.
[0024] FIG. 8 is a voltage profile of the first, third and fifth
discharge cycles for a LiFePO.sub.4/2.18% carbon-containing cathode
(0% binder) cycled in a cell using the test conditions described
with respect to FIG. 2.
[0025] FIG. 9 is a voltage profile of the first, third and fifth
discharge cycles for a Li.sub.0.98Mg.sub.0.01FePO.sub.4/1.88%
carbon-containing cathode (0% binder) cycled in a cell using the
test conditions described with respect to FIG. 2.
[0026] FIG. 10 is a voltage profile of the first, third and fifth
discharge cycles for a LiMg.sub.0.04Fe.sub.0.96PO.sub.4/2.24%
carbon-containing cathode (0% binder) cycled in a cell using the
test conditions described with respect to FIG. 2.
[0027] FIG. 11 is a voltage profile of the first, third and fifth
discharge cycles for a
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4/1.98% carbon-containing
cathode (0% binder) cycled in a cell using the test conditions
described with respect to FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] It has been found that the novel electrode materials,
electrodes, and batteries of this invention afford benefits over
such materials and devices among those known in the art. Such
benefits include one or more of increased capacity, enhanced
cycling capability, enhanced reversibility, enhanced ionic
conductivity, enhanced electrical conductivity, and reduced costs.
Specific benefits and embodiments of the present invention are
apparent from the detailed description set forth herein below. It
should be understood, however, that the detailed description and
specific examples, while indicating embodiments among those
preferred, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
[0029] The present invention provides electrode active materials
for use in an electricity-producing electrochemical cell. Each
electrochemical cell includes a positive electrode, a negative
electrode, and an electrolyte in ion-transfer relationship with
each electrode. As used herein, the word "include," and its
variants, is intended to be non-limiting, such that recitation of
items in a list is not to the exclusion of other like items that
may also be useful in the materials, compositions, devices, and
methods of this invention. A "battery" refers to a device having
one or more electricity-producing electrochemical cells. Two or
more electrochemical cells may be combined in parallel or series,
or "stacked," so as to create a multi-cell battery.
[0030] The electrode active materials of this invention may be used
in the negative electrode, the positive electrode, or both.
Preferably, the active materials of this invention are used in the
positive electrode (As used herein, the terms "negative electrode"
and "positive electrode" refer to the electrodes at which oxidation
and reduction occur, respectively, during battery discharge; during
charging of the battery, the sites of oxidation and reduction are
reversed). The terms "preferred" and "preferably" as used herein
refer to embodiments of the invention that afford certain benefits,
under certain circumstances. However, other embodiments may also be
preferred, under the same or other circumstances. Furthermore, the
recitation of one or more preferred embodiments does not imply that
other embodiments are not useful and is not intended to exclude
other embodiments from the scope of the invention.
ELECTRODE ACTIVE MATERIALS OF THE PRESENT INVENTION
[0031] The present invention is directed to a novel alkali
metal-containing electrode active material. In one embodiment, the
novel active material of the present invention is represented by
the nominal general formula (I): [A.sub.a, D.sub.d]M.sub.m(XY.sub.4
).sub.pZ.sub.e. (I)
[0032] The term "nominal general formula" refers to the fact that
the relative proportion of atomic species may vary slightly on the
order of 2 percent to 5 percent, or more typically, 1 percent to 3
percent. The composition of A, D, M, XY.sub.4 and Z of general
formulas (I) through (V) herein, as well as the stoichiometric
values of the elements of the active material, are selected so as
to maintain electroneutrality of the electrode active material. The
stoichiometric values of one or more elements of the composition
may take on non-integer values.
[0033] For all embodiments described herein, A is selected from the
group consisting of elements from Group I of the Periodic Table,
and mixtures thereof (e.g. A.sub.a=A.sub.a-a'A'.sub.a', wherein A
and A' are each selected from the group consisting of elements from
Group I of the Periodic Table and are different from one another,
and a'<a). As referred to herein, "Group" refers to the Group
numbers (i.e., columns) of the Periodic Table as defined in the
current IUPAC Periodic Table. (See, e.g., U.S. Pat. No. 6,136,472,
Barker et al., issued Oct. 24, 2000, incorporated by reference
herein.) In addition, the recitation of a genus of elements,
materials or other components, from which an individual component
or mixture of components can be selected, is intended to include
all possible sub-generic combinations of the listed components, and
mixtures thereof.
[0034] In one embodiment, A is selected from the group consisting
of Li (Lithium), Na (Sodium), K (Potassium), and mixtures thereof.
A may be mixture of Li with Na, a mixture of Li with K, or a
mixture of Li, Na and K. In another embodiment, A is Na, or a
mixture of Na with K. In one preferred embodiment, A is Li.
[0035] A sufficient quantity (a) of moiety A should be present so
as to allow all of the "redox active" elements of the moiety M (as
defined herein below) to undergo oxidation/reduction. In one
embodiment, 0<a.ltoreq.9. In another embodiment,
0<a.ltoreq.2. Unless otherwise specified, a variable described
herein algebraically as equal to ("="), less than or equal to
(".ltoreq."), or greater than or equal to (".gtoreq.") a number is
intended to subsume values or ranges of values about equal or
functionally equivalent to said number.
[0036] Removal of an amount of A from the electrode active material
is accompanied by a change in oxidation state of at least one of
the "redox active" elements in the active material, as defined
herein below. The amount of redox active material available for
oxidation/reduction in the active material determines the amount
(a) of the moiety A that may be removed. Such concepts are, in
general application, well known in the art, e.g., as disclosed in
U.S. Pat. No. 4,477,541, Fraioli, issued Oct. 16, 1984; and U.S.
Pat. No. 6,136,472, Barker, et al., issued Oct. 24, 2000, both of
which are incorporated by reference herein.
[0037] In general, the amount (a) of moiety A in the active
material varies during charge/discharge. Where the active materials
of the present invention are synthesized for use in preparing an
alkali metal-ion battery in a discharged state, such active
materials are characterized by a relatively high value of "a", with
a correspondingly low oxidation state of the redox active
components of the active material. As the electrochemical cell is
charged from its initial uncharged state, an amount (b) of moiety A
is removed from the active material as described above. The
resulting structure, containing less amount of the moiety A (i.e.,
a-b) than in the as-prepared state, and at least one of the redox
active components having a higher oxidation state than in the
as-prepared state, while essentially maintaining the original
values of the remaining components (e.g. D, M, X, Y and Z). The
active materials of this invention include such materials in their
nascent state (i.e., as manufactured prior to inclusion in an
electrode) and materials formed during operation of the battery
(i.e., by insertion or removal of A).
[0038] For all embodiments described herein, D is at least one
element having an atomic radius substantially comparable to that of
the moiety being substituted (e.g. moiety M and/or moiety A). In
one embodiment, D is at least one transition metal. Examples of
transition metals useful herein with respect to moiety D include,
without limitation, Nb (Niobium), Zr (Zirconium), Ti (Titanium), Ta
(Tantalum), Mo (Molybdenum), W (Tungsten), and mixtures thereof. In
another embodiment, moiety D is at least one element characterized
as having a valence state of .gtoreq.2+ and an atomic radius that
is substantially comparable to that of the moiety being substituted
(e.g. M and/or A). With respect to moiety A, examples of such
elements include, without limitation, Nb (Niobium), Mg (Magnesium)
and Zr (Zirconium). Preferably, the valence or oxidation state of D
(V.sup.D) is greater than the valence or oxidation state of the
moiety (or sum of oxidation states of the elements consisting of
the moiety) being substituted for by moiety D (e.g. moiety M and/or
moiety A).
[0039] While not wishing to be held to any one theory, with respect
to moiety A, it is thought that by incorporating a dopant (D) into
the crystal structure of the active material of the present
invention, wherein the amount (a) of moiety A initially present in
the active material is substituted by an amount of D, the dopant
will occupy sites in the active material normally occupied by A,
thus substantially increasing the ionic and electrical conductivity
of the active material. Such materials additionally exhibit
enhanced electrical conductivity, thus reducing or eliminating the
need for electrically conductive material (e.g. carbon) in the
electrode. Reduction or elimination of carbonaceous materials in
secondary electrochemical cells, including those disclosed herein,
is desirable because of the long-term deleterious effects
carbonaceous materials produce during the operation of the
electrochemical cells (e.g. promotion of gas production within the
electrochemical cell). Reduction or elimination of the carbonaceous
material also permits insertion of a greater amount of active
material, thereby increasing the electrochemical cell's capacity
and energy density.
[0040] Moiety A may be partially substituted by moiety D by
aliovalent or isocharge substitution, in equal or unequal
stoichiometric amounts. "Isocharge substitution" refers to a
substitution of one element on a given crystallographic site with
an element having the same oxidation state (e.g. substitution of
Ca.sup.2+ with Mg.sup.2+). "Aliovalent substitution" refers to a
substitution of one element on a given crystallographic site with
an element of a different oxidation state (e.g. substitution of
Li.sup.+ with Mg.sup.2+).
[0041] For all embodiments described herein where moiety A is
partially substituted by moiety D by isocharge substitution, A may
be substituted by an equal stoichiometric amount of moiety D,
whereby the active material of the present invention is represented
by the nominal general formula (II):
[A.sub.a-f,D.sub.d]M.sub.m(XY.sub.4).sub.pZ.sub.e, (II) wherein
f=d.
[0042] Where moiety A of general formula (II) is partially
substituted by moiety D by isocharge substitution and d.noteq.f,
then the stoichiometric amount of one or more of the other
components (e.g. A, M, XY.sub.4 and Z) in the active material must
be adjusted in order to maintain electroneutrality.
[0043] For all embodiments described herein where moiety A is
partially substituted by moiety D by aliovalent substitution,
moiety A may be substituted by an "oxidatively" equivalent amount
of moiety D, whereby the active material of the present invention
is represented by the nominal general formula (III): [ A a .times.
f V A , D d V D ] .times. M m .function. ( XY 4 ) p .times. Z e , (
III ) ##EQU1## wherein f=d, V.sup.A is the oxidation state of
moiety A (or sum of oxidation states of the elements consisting of
the moiety A), and V.sup.D is the oxidation state of moiety D.
[0044] Where moiety A of general formula (III) is partially
substituted by moiety D by aliovalent substitution and d.noteq.f,
then the stoichiometric amount of one or more of the other
components (e.g. A, M, XY.sub.4 and Z) in the active material must
be adjusted in order to maintain electroneutrality.
[0045] In one embodiment, moiety M is partially substituted by
moiety D by aliovalent or isocharge substitution, in equal or
unequal stoichiometric amounts. In this embodiment, d.gtoreq.0,
wherein moiety A may be substituted by moiety D by aliovalent or
isocharge substitution, in equal or unequal stoichiometric amounts.
Where moieties M and A are both partially substituted by moiety D,
the elements selected for substitution for each moiety may be the
same or different from one another.
[0046] For all embodiments described herein where moiety M is
partially substituted by moiety D by isocharge substitution, M may
be substituted by an equal stoichiometric amount of moiety D,
whereby M=[M.sub.m-u,D.sub.v], wherein u=v. Where moiety M is
partially substituted by moiety D by isocharge substitution and
u.noteq.v, then the stoichiometric amount of one or more of the
other components (e.g. A, M, XY.sub.4 and Z) in the active material
must be adjusted in order to maintain electroneutrality.
[0047] For all embodiments described herein where moiety M is
partially substituted by moiety D by aliovalent substitution,
moiety M may be substituted by an "oxidatively" equivalent amount
of moiety D, whereby [ M m - u V m , D v V D ] , ##EQU2## wherein
u=v, V.sup.M is the oxidation state of moiety M (or sum of
oxidation states of the elements consisting of the moiety M), and
V.sup.D is the oxidation state of moiety D.
[0048] Where moiety M is partially substituted by moiety D by
aliovalent substitution and u.noteq.v, then the stoichiometric
amount of one or more of the other components (e.g. A, M, XY.sub.4
and Z) in the active material must be adjusted in order to maintain
electroneutrality.
[0049] In this embodiment, moiety M and (optionally) moiety A are
each partially substituted by aliovalent or isocharge substitution.
While not wishing to be held to any one theory, it is thought that
by incorporating a dopant (D) into the crystal structure of the
active material of the present invention in this manner, wherein
the stoichiometric values M and (optionally) A are dependent on
(reduced by) the amount of dopant provided for each
crystallographic site, that the dopant will occupy sites in the
active material normally occupied by moiety M and (optionally)
moiety A. First, where V.sup.D>V.sup.A, doping sites normally
occupied by A increases the number of available or unoccupied sites
for A, thus substantially increasing the ionic and electrical
conductivity of the active material. Second, doping the M sites
reduces the concentration of available redox active elements, thus
ensuring some amount of A remains in the active material upon
charge, thereby increasing the structural stability of the active
material. Such materials additionally exhibit enhanced electrical
conductivity, thus reducing or eliminating the need for
electrically conductive material in the electrode.
[0050] In all embodiments described herein, moiety M is at least
one redox active element. As used herein, the term "redox active
element" includes those elements characterized as being capable of
undergoing oxidation/reduction to another oxidation state when the
electrochemical cell is operating under normal operating
conditions. As used herein, the term "normal operating conditions"
refers to the intended voltage at which the cell is charged, which,
in turn, depends on the materials used to construct the cell.
[0051] Redox active elements useful herein with respect to moiety M
include, without limitation, elements from Groups 4 through 11 of
the Periodic Table, as well as select non-transition metals,
including, without limitation, Ti (Titanium), V (Vanadium), Cr
(Chromium), Mn (Manganese), Fe (Iron), Co (Cobalt), Ni (Nickel), Cu
(Copper), Nb (Niobium), Mo (Molybdenum), Ru (Ruthenium), Rh
(Rhodium), Pd (Palladium), Os (Osmium), Ir (Iridium), Pt
(Platinum), Au (Gold), Si (Silicon), Sn (Tin), Pb (Lead), and
mixtures thereof. Also, "include," and its variants, is intended to
be non-limiting, such that recitation of items in a list is not to
the exclusion of other like items that may also be useful in the
materials, compositions, devices, and methods of this
invention.
[0052] In one embodiment, moiety M is a redox active element. In
one subembodiment, M is a redox active element selected from the
group consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+,
Fe.sup.2+, Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+,
Sn.sup.2+, and Pb.sup.2+. In another subembodiment, M is a redox
active element selected from the group consisting of Ti.sup.3+,
V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+, Ni.sup.3+,
Mo.sup.3+, and Nb.sup.3+.
[0053] In another embodiment, moiety M is a mixture of redox active
elements or a mixture of at least one redox active element and at
least one non-redox active element. As referred to herein,
"non-redox active elements" include elements that are capable of
forming stable active materials, and do not undergo
oxidation/reduction when the electrode active material is operating
under normal operating conditions.
[0054] Among the non-redox active elements useful herein include,
without limitation, those selected from Group 2 elements,
particularly Be (Beryllium), Mg (Magnesium), Ca (Calcium), Sr
(Strontium), Ba (Barium); Group 3 elements, particularly Sc
(Scandium), Y (Yttrium), and the lanthanides, particularly La
(Lanthanum), Ce (Cerium), Pr (Praseodymium), Nd (Neodymium), Sm
(Samarium); Group 12 elements, particularly Zn (Zinc) and Cd
(Cadmium); Group 13 elements, particularly B (Boron), Al
(Aluminum), Ga (Gallium), In (Indium), Tl (Thallium); Group 14
elements, particularly C (Carbon) and Ge (Germanium), Group 15
elements, particularly As (Arsenic), Sb (Antimony), and Bi
(Bismuth); Group 16 elements, particularly Te (Tellurium); and
mixtures thereof.
[0055] In one embodiment, M=MI.sub.nMII.sub.o, wherein
0<o+n.ltoreq.3 and each of o and n is greater than zero
(0<o,n), wherein MI and MII are each independently selected from
the group consisting of redox active elements and non-redox active
elements, wherein at least one of MI and MII is redox active. MI
may be partially substituted with MII by isocharge or aliovalent
substitution, in equal or unequal stoichiometric amounts.
[0056] For all embodiments described herein where MI is partially
substituted by MII by isocharge substitution, MI may be substituted
by an equal stoichiometric amount of MII, whereby
M=MI.sub.n-oMII.sub.o. Where MI is partially substituted by MII by
isocharge substitution and the stoichiometric amount of MI is not
equal to the amount of MII, whereby M=MI.sub.n-oMII.sub.p and
o.noteq.p, then the stoichiometric amount of one or more of the
other components (e.g. A, D, XY.sub.4 and Z) in the active material
must be adjusted in order to maintain electroneutrality.
[0057] For all embodiments described herein where MI is partially
substituted by MII by aliovalent substitution and an equal amount
of MI is substituted by an equal amount of MII, whereby
M=MI.sub.n-oMII.sub.o, then the stoichiometric amount of one or
more of the other components (e.g. A, D, XY.sub.4 and Z) in the
active material must be adjusted in order to maintain
electroneutrality. However, MI may be partially substituted by MII
by aliovalent substitution by substituting an "oxidatively"
equivalent amount of MII for MI, whereby M = MI n - o V MI .times.
MII o V MII , ##EQU3## wherein V.sup.MI is the oxidation state of
MI, and V.sup.MII is the oxidation state of MII.
[0058] In one subembodiment, MI is selected from the group
consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Si, Pb, Mo, Nb,
and mixtures thereof, and MII is selected from the group consisting
of Be, Mg, Ca, Sr, Ba, Sc, Y, Zn, Cd, B, Al, Ga, In, C, Ge, and
mixtures thereof. In this subembodiment, MI may be substituted by
MII by isocharge substitution or aliovalent substitution.
[0059] In another subembodiment, MI is partially substituted by MII
by isocharge substitution. In one aspect of this subembodiment, MI
is selected from the group consisting of Ti.sup.2+, V.sup.2+,
Cr.sup.2+, Mn.sup.2+, Fe.sup.2+, Co.sup.2+, Ni.sup.2+, Cu.sup.2+,
Mo.sup.2+, Si.sup.2+, Sn.sup.2+, Pb.sup.2+, and mixtures thereof,
and MII is selected from the group consisting of Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Zn.sup.2+, Cd.sup.2+,
Ge.sup.2+, and mixtures thereof. In another aspect of this
subembodiment, MI is selected from the group specified immediately
above, and MII is selected from the group consisting of Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, and mixtures thereof.
In another aspect of this subembodiment, MI is selected from the
group specified above, and MII is selected from the group
consisting of Zn.sup.2+, Cd.sup.2+, and mixtures thereof. In yet
another aspect of this subembodiment, MI is selected from the group
consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Co.sup.3+, Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof,
and MII is selected from the group consisting of Sc.sup.3+,
Y.sup.3+, B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures
thereof.
[0060] In another embodiment, MI is partially substituted by MII by
aliovalent substitution. In one aspect of this subembodiment, MI is
selected from the group consisting of Ti.sup.2+, V.sup.2+,
Cr.sup.2+, Mn.sup.2+, Fe.sup.2+, Co.sup.2+, Ni.sup.2+, Cu.sup.2+,
Mo.sup.2+, Si.sup.2+, Sn.sup.2+, Pb.sup.2+, and mixtures thereof,
and MII is selected from the group consisting of Sc.sup.3+,
Y.sup.3+, B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures
thereof. In another aspect of this subembodiment, MI is a 2+
oxidation state redox active element selected from the group
specified immediately above, and MII is selected from the group
consisting of alkali metals, Cu.sup.1+, Ag.sup.1+ and mixtures
thereof. In another aspect of this subembodiment, MI is selected
from the group consisting of Ti.sup.3+, V.sup.3+, Cr.sup.3+,
Mn.sup.3+, Fe.sup.3+, Co.sup.3+, Ni.sup.3+, Mo.sup.3+, Nb.sup.3+,
and mixtures thereof, and MII is selected from the group consisting
of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+,
Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures thereof. In another
aspect of this subembodiment, MI is a 3+ oxidation state redox
active element selected from the group specified immediately above,
and MII is selected from the group consisting of alkali metals,
Cu.sup.1+, Ag.sup.1+ and mixtures thereof.
[0061] In another embodiment, M=M1.sub.qM2.sub.rM3.sub.s,
wherein:
[0062] (a) M1 is a redox active element with a 2+ oxidation
state;
[0063] (b) M2 is selected from the group consisting of redox and
non-redox active elements with a 1+ oxidation state;
[0064] (c) M3 is selected from the group consisting of redox and
non-redox active elements with a 3+ oxidation state; and
[0065] (d) at least one of p, q and r is greater than 0, and at
least one of M1, M2, and M3 is redox active.
[0066] In one subembodiment, M1 is substituted by an equal amount
of M2 and/or M3, whereby q=q-(r+s). In this subembodiment, then the
stoichiometric amount of one or more of the other components (e.g.
A, XY.sub.4, Z) in the active material must be adjusted in order to
maintain electroneutrality.
[0067] In another subembodiment, M.sup.1 is substituted by an
"oxidatively" equivalent amount of M.sup.2 and/or M.sup.3, whereby
M = M .times. .times. 1 q - r V M1 - s V M1 .times. M .times.
.times. 2 r V M2 .times. M .times. .times. 3 s V M3 , ##EQU4##
wherein V.sup.M1 is the oxidation state of M1, V.sup.M2 is the
oxidation state of M2, and V.sup.M3 is the oxidation state of
M3.
[0068] In one subembodiment, M1 is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof; M2 is selected from the group
consisting of Cu.sup.1+, Ag.sup.1+ and mixtures thereof; and M3 is
selected from the group consisting of Ti.sup.3+, V.sup.3+,
Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+, Ni.sup.3+, Mo.sup.3+,
Nb.sup.3+, and mixtures thereof. In another subembodiment, M1 and
M3 are selected from their respective preceding groups, and M2 is
selected from the group consisting of Li.sup.1+, K.sup.1+,
Na.sup.1+, Ru.sup.1+, Cs.sup.1+, and mixtures thereof.
[0069] In another subembodiment, M1 is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures thereof;
M2 is selected from the group consisting of Cu.sup.1+, Ag.sup.1+
and mixtures thereof; and M3 is selected from the group consisting
of Ti.sup.3+, V.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+,
Ni.sup.3+, Mo.sup.3+, Nb.sup.3+, and mixtures thereof. In another
subembodiment, M1 and M3 are selected from their respective
preceding groups, and M2 is selected from the group consisting of
Li.sup.1+, K.sup.1+, Na.sup.1+, Ru.sup.1+, Cs.sup.1+, and mixtures
thereof.
[0070] In another subembodiment, M1 is selected from the group
consisting of Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+,
Pb.sup.2+, and mixtures thereof; M2 is selected from the group
consisting of Cu.sup.1+, Ag.sup.1+, and mixtures thereof; and M3 is
selected from the group consisting of Sc.sup.3+, Y.sup.3+,
B.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, and mixtures thereof. In
another subembodiment, M1 and M3 are selected from their respective
preceding groups, and M2 is selected from the group consisting of
Li.sup.1+, K.sup.1+, Na.sup.1+, Ru.sup.1+, Cs.sup.1+, and mixtures
thereof.
[0071] In all embodiments described herein, moiety XY.sub.4 is a
polyanion selected from the group consisting of
X'[O.sub.4-x,Y'.sub.x], X'[O.sub.4-y,Y'.sub.2y], X''S.sub.4,
[X.sub.z''',X'.sub.1-z]O.sub.4, and mixtures thereof, wherein:
[0072] (a) X' and X''' are each independently selected from the
group consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof;
[0073] (b) X'' is selected from the group consisting of P, As, Sb,
Si, Ge, V, and mixtures thereof; [0074] (c) Y' is selected from the
group consisting of a halogen, S, N, and mixtures thereof; and
[0075] (d) 0.ltoreq.x.ltoreq.3,0.ltoreq.y.ltoreq.2,and
0.ltoreq.z.ltoreq.1.
[0076] In one embodiment, 1.ltoreq.p.ltoreq.3. In one
subembodiment, p=1. In another subembodiment, p=3.
[0077] In one embodiment, XY.sub.4 is selected from the group
consisting of X'O.sub.4- .sub.xY'.sub.x, X'O.sub.4-y,Y'.sub.2y, and
mixtures thereof, and x and y are both 0. Stated otherwise,
XY.sub.4 is a polyanion selected from the group consisting of
PO.sub.4, SiO.sub.4, GeO.sub.4, VO.sub.4, AsO.sub.4, SbO.sub.4,
SO.sub.4, and mixtures thereof. Preferably, XY.sub.4 is PO.sub.4 (a
phosphate group) or a mixture of PO.sub.4 with another anion of the
above-noted group (i.e., where X' is not P, Y' is not O, or both,
as defined above). In one embodiment, XY.sub.4 includes about 80%
or more phosphate and up to about 20% of one or more of the
above-noted anions.
[0078] In another embodiment, XY.sub.4 is selected from the group
consisting of X'[O.sub.4-x,Y'.sub.x], X'[O.sub.4-y,Y'.sub.2y], and
mixtures thereof, and 0<x.ltoreq.3 and 0<y.ltoreq.2, wherein
a portion of the oxygen (O) in the XY.sub.4 moiety is substituted
with a halogen, S, N, or a mixture thereof.
[0079] In all embodiments described herein, moiety Z (when
provided) is selected from the group consisting of OH (Hydroxyl), a
halogen, or mixtures thereof. In one embodiment, Z is selected from
the group consisting of OH, F (Fluorine), Cl (Chlorine), Br
(Bromine), and mixtures thereof. In another embodiment, Z is OH. In
another embodiment, Z is F, or a mixture of F with OH, Cl, or Br.
Where the moiety Z is incorporated into the active material of the
present invention, the active material may not take on a NASICON or
olivine structural where p=3 or d=1, respectively. It is quite
normal for the symmetry to be reduced with incorporation of, for
example, halogens.
[0080] The composition of the electrode active material, as well as
the stoichiometric values of the elements of the composition, are
selected so as to maintain electroneutrality of the electrode
active material. The stoichiometric values of one or more elements
of the composition may take on non-integer values. Preferably, the
XY.sub.4 moiety is, as a unit moiety, an anion having a charge of
-2, -3, or -4, depending on the selection of X', X'', X''' Y', and
x and y. When XY.sub.4 is a mixture of polyanions such as the
preferred phosphate/phosphate substitutes discussed above, the net
charge on the XY.sub.4 anion may take on non-integer values,
depending on the charge and composition of the individual groups
XY.sub.4 in the mixture.
[0081] In one particular embodiment, the electrode active material
has an orthorhombic--dipyramidal crystal structure and belongs to
the space group Pbnm (e.g. an olivine or triphylite material), and
is represented by the nominal general formula (IV):
[A.sub.a,D.sub.d]M.sub.mXY.sub.4Z.sub.e, (IV) wherein:
[0082] (a) the moieties A, D, M, X, Y and Z are as defined herein
above;
[0083] (b) 0<a.ltoreq.2,0<d.ltoreq.1; 1<m.ltoreq.2,and
0<d.ltoreq.1;and
[0084] (c) the components of the moieties A, D, M, X, Y, and Z, as
well as the values for a, d, m and e, are selected so as to
maintain electroneutrality of the compound.
[0085] In one particular subembodiment, A of general formula (IV)
is Li, 0.5<a.ltoreq.1.5, M=MI.sub.n-pMII.sub.o, wherein o=p,
0.5<n.ltoreq.1.5, 0<o.ltoreq.0.1, MI is a 2+ oxidation state
redox active element selected from the group consisting of
Ti.sup.2+, V.sup.2+, Cr.sup.2+, Mn.sup.2+, Fe.sup.2+, Co.sup.2+,
Ni.sup.2+, Cu.sup.2+, Mo.sup.2+, Si.sup.2+, Sn.sup.2+, and
Pb.sup.2+ (preferably Fe.sup.2+), MII is selected from the group
consisting of Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+,
Ba.sup.2+, Zn.sup.2+, Cd.sup.2+, Ge.sup.2+, and mixtures thereof
(preferably Mg.sup.2+or Ca.sup.2+), XY.sub.4.dbd.PO.sub.4, and
e=0.
[0086] In another particular embodiment, the electrode active
material has a rhombohedral (space group R-3) or monoclinic (space
group Pbcn) NASICON structure, and is represented by the nominal
general formula (V):
[A.sub.a,D.sub.d]M.sub.m(XY.sub.4).sub.3Z.sub.e, (V) wherein:
[0087] (a) the moieties A, D, M, X, Y and Z are as defined herein
above;
[0088] (b) 0<a.ltoreq.5, 0<d.ltoreq.1; 1<m.ltoreq.3,and
0<e.ltoreq.4;and
[0089] (c) the components of the moieties A, D, M, X, Y, and Z, as
well as the values for a, d, m and e, are selected so as to
maintain electroneutrality of the compound.
[0090] In one particular subembodiment, A of general formula (V) is
Li, M is selected from the group consisting of Ti.sup.3+, V.sup.3+,
Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Co.sup.3+, Ni.sup.3+, Mo.sup.3+,
Nb.sup.3+, and mixtures thereof (preferably V.sup.3+),
XY.sub.4.dbd.PO.sub.4, and e=0.
Methods of Manufacture:
[0091] The particular starting materials employed will depend on
the particular active material to be synthesized, reaction method
employed, and desired by-products. The compound of the present
invention is synthesized by reacting at least one A-containing
compound, at least one D-containing compound, one or more
M-containing compounds, at least one XY.sub.4-supplying or
containing compound, and (optionally) one or more Z-containing
compounds, at a temperature and for a time sufficient to form the
desired reaction product. As used herein, the term "supplying"
includes compounds which contain the particular component, or
reacts to form the particular component so specified.
[0092] Sources of the moiety A include any of a number of Group I
metal-containing salts or ionic compounds. Lithium, sodium, and
potassium compounds are preferred, with lithium being particularly
preferred. Examples include, without limitation, alkali
metal-containing fluorides, chlorides, bromides, iodides, nitrates,
nitrites, sulfates, hydrogen sulfates, sulfites, bisulfites,
carbonates, bicarbonates, borates, phosphates, silicates,
antimonates, arsenates, germinates, oxides, acetates, oxalates, and
the like. Hydrates of the above compounds may also be used, as well
as mixtures thereof. The mixtures may contain more than one alkali
metal so that a mixed alkali metal active material will be produced
in the reaction.
[0093] Sources of the moieties M and D include, without limitation,
M/D-containing fluorides, chlorides, bromides, iodides, nitrates,
nitrites, sulfates, hydrogen sulfates, sulfites, bisulfites,
carbonates, bicarbonates, borates, phosphates, hydrogen ammonium
phosphates, dihydrogen ammonium phosphates, silicates, antimonates,
arsenates, germanates, oxides, hydroxides, acetates, and oxalates
of the same. Hydrates may also be used. The moiety M in the
starting material may have any oxidation state, depending on the
oxidation state required in the desired product and the oxidizing
or reducing conditions contemplated, if any. It should be noted
that many of the above-noted compounds may also function as a
source of the XY.sub.4 moiety.
[0094] The active materials described herein can contain one or
more XY.sub.4 moieties, or can contain a phosphate group that is
completely or partially substituted by a number of other XY.sub.4
moieties, which will also be referred to as "phosphate
replacements" or "modified phosphates." Thus, active materials are
provided according to the invention wherein the XY.sub.4 moiety is
a phosphate group that is completely or partially replaced by such
moieties as sulfate (SO.sub.4).sup.2-, monofluoromonophosphate,
(PO.sub.3F).sup.2-, difluoromonophosphate (PO.sub.2F).sup.2-,
silicate (SiO.sub.4).sup.4-, arsenate, antimonate, vanadate,
titanate, and germanate. Analogues of the above oxygenate anions
where some or all of the oxygen is replaced by sulfur are also
useful in the active materials of the invention, with the exception
that the sulfate group may not be completely substituted with
sulfur. For example, thiomonophosphates may also be used as a
complete or partial replacement for phosphate in the active
materials of the invention. Such thiomonophosphates include the
anions (PO.sub.3S).sup.3-, (PO.sub.2S.sub.2).sup.3-,
(POS.sub.3).sup.3-, and (PS.sub.4).sup.3-, and are most
conveniently available as the sodium, lithium, or potassium
derivative. Non-limiting examples of sources of
monofluoromonophosphates include, without limitation,
Na.sub.2PO.sub.3F, K.sub.2PO.sub.3F,
(NH.sub.4).sub.2PO.sub.3F.H.sub.2O, LiNaPO.sub.3F.H.sub.2O,
LiKPO.sub.3F, LiNH.sub.4PO.sub.3F, NaNH.sub.4PO.sub.3F,
NaK.sub.3(PO.sub.3F).sub.2 and CaPO.sub.3F.2H.sub.2O.
Representative examples of sources of difluoromonophosphate
compounds include, without limitation, NH.sub.4PO.sub.2F.sub.2,
NaPO.sub.2F.sub.2, KPO.sub.2F.sub.2, Al(PO.sub.2F.sub.2).sub.3, and
Fe(PO.sub.2F.sub.2).sub.3.
[0095] Sources for the XY.sub.4 moiety are common and readily
available. For example, where X is Si, useful sources of silicon
include orthosilicates, pyrosilicates, cyclic silicate anions such
as (Si.sub.3O.sub.9).sup.6-, (Si.sub.6O.sub.18).sup.12- and the
like, and pyrocenes represented by the formula
[(SiO.sub.3).sup.2-]n, for example LiAl(SiO.sub.3).sub.2. Silica or
SiO.sub.2 may also be used. Representative arsenate compounds that
may be used to prepare the active materials of the invention,
wherein X is As, include H.sub.3AsO.sub.4 and salts of the anions
[H.sub.2AsO.sub.4].sup.- and [HAsO.sub.4].sup.2-. Where X is Sb,
antimonate can be provided by antimony-containing materials such as
Sb.sub.2O.sub.5, M.sup.ISbO.sub.3 where M.sup.I is a metal having
oxidation state 1+, M.sup.IIISbO.sub.4 where M.sup.III is a metal
having an oxidation state of 3+, and M.sup.IISb.sub.2O.sub.7 where
M.sup.II is a metal having an oxidation state of 2+. Additional
sources of antimonate include compounds such as Li.sub.3SbO.sub.4,
NH.sub.4H.sub.2SbO.sub.4, and other alkali metal and/or ammonium
mixed salts of the [SbO.sub.4].sup.3- anion. Where X is S, sulfate
compounds that can be used to synthesize the active material
include alkali metal and transition metal sulfates and bisulfates
as well as mixed metal sulfates such as
(NH.sub.4).sub.2Fe(SO.sub.4).sub.2, NH.sub.4Fe(SO.sub.4).sub.2 and
the like. Finally, where X is Ge, a germanium containing compound
such as GeO.sub.2 may be used to synthesize the active
material.
[0096] Where Y' of the X'O.sub.4-xY'.sub.x and X'O.sub.4-yY'2y
moieties is F, sources of F include ionic compounds containing
fluoride ion (F.sup.-) or hydrogen difluoride ion (HF.sub.2.sup.-).
The cation may be any cation that forms a stable compound with the
fluoride or hydrogen difluoride anion. Examples include 1+, 2+ and
3+ metal cations, as well as ammonium and other nitrogen-containing
cations. Ammonium is a preferred cation because it tends to form
volatile by-products that are readily removed from the reaction
mixture. Similarly, to make X'O.sub.4-xN.sub.x, starting materials
are provided that contain "x" moles of a source of nitride ion.
Sources of nitride are among those known in the art including
nitride salts such as Li.sub.3N and (NH.sub.4).sub.3N.
[0097] As noted above, the active materials of the present
invention contain a mixture of A, D, M, XY.sub.4, and (optionally)
Z. A starting material may provide more than one these components,
as is evident in the list above. In various embodiments of the
invention, starting materials are provided that combine, for
example, M and PO.sub.4, thus requiring only the alkali metal and D
to be added. In one embodiment, a starting material is provided
that contains A, M and PO.sub.4. As a general rule, there is
sufficient flexibility to allow selection of starting materials
containing any of the components of alkali metal A, D, M, XY.sub.4,
and (optionally) Z, depending on availability. Combinations of
starting materials providing each of the components may also be
used.
[0098] In general, any counterion may be combined with A, D, M,
XY.sub.4, and Z. It is preferred, however, to select starting
materials with counterions that give rise to the formation of
volatile by-products during the reaction. Thus, it is desirable to
choose ammonium salts, carbonates, bicarbonates, oxides,
hydroxides, and the like, where possible. Starting materials with
these counterions tend to form volatile by-products such as water,
ammonia, and carbon dioxide, which can be readily removed from the
reaction mixture. Similarly, sulfur-containing anions such as
sulfate, bisulfate, sulfite, bisulfite and the like tend to result
in volatile sulfur oxide by-products. Nitrogen-containing anions
such as nitrate and nitrite also tend to give volatile NO.sub.x
by-products. This concept is well illustrated in the examples
below.
[0099] Additionally, in some cases the performance of the active
material may be dependent upon the amount of each reactant present
in the reaction mixture. This is because the presence of certain
unreacted starting materials in the active material may have a
detrimental effect on the electrochemical performance of the active
material. For example, with respect to the active material
Li.sub.aMg.sub.bFe.sub.cPO.sub.4, synthesized via a solid state
reaction of LiH.sub.2PO.sub.4 and Fe.sub.2O.sub.3 in the presence
of a reducing agent (as defined herein below), it has been
discovered that the presence of Fe.sub.2O.sub.3 in the reaction
product has a deleterious effect on the electrochemical performance
of the active material. Therefore, in this particular reaction, it
is preferred that the Fe.sub.2O.sub.3 be the limiting reagent to
ensure that substantially all of the Fe.sub.2O.sub.3 reacts.
Preferably, for this particular reaction, it is preferred that the
P to M ration (P:M) be approximately 1:0.95 to about 1:0.99.
Furthermore, depending on the particular source of
LiH.sub.2PO.sub.4, the Li:P ratio of LiH.sub.2PO.sub.4 may not be
exactly 1:1 due to the presence of unreacted reactants used to
synthesize LiH.sub.2PO.sub.4 (e.g. H.sub.3PO.sub.4). For example,
if a LiH.sub.2PO.sub.4 material of 98% purity (e.g. containing 2%
H.sub.3PO.sub.4) is employed, the Li:P ration in the reaction
mixture is 0.98:1. Preferably, the overall Li:P:M ratio is from
about 0.95:1:95 to about 0.99:1:0.99, and most preferably
0.98:1:0.96. Thus, as can be seen from the above-noted example, one
with ordinary skill in the art would readily be able to optimize
the electrochemical performance of the active material synthesized
by choosing one of the reactant to be the limiting reagent, taking
into account any impurities present in the reaction mixture, and
comparing the electrochemical performance of the resulting active
material to similar active materials wherein alternate reactants
are chosen to be the limiting reagent.
[0100] One method for preparing the active materials of the present
invention is via the hydrothermal treatment of the requisite
starting materials. In a hydrothermal reaction, the starting
materials are mixed with a small amount of a liquid (e.g. water),
and heated in a pressurized vessel or bomb at a temperature that is
relatively lower as compared to the temperature necessary to
produce the active material in an oven at ambient pressure.
Preferably, the reaction is carried out at a temperature of about
150.degree. C. to about 450.degree. C., under pressure, for a
period of about 4 to about 48 hours, or until a reaction product
forms.
[0101] A "sol-gel" preparation method may also be employed. Using
this method, solute precursors with the required component are
mixed in solution and then transformed into a solid via
precipitation or gelation. The result wet powder or gel are dried
at temperature in the range of about 100.degree. C. to about
400.degree. C. for short time and then, optionally, heated up to
about 450.degree. C. to about 700.degree. C. in controlled
atmosphere for about 1 hour to about 4 hours.
[0102] Another method for synthesizing the active materials of the
present invention is via a thermite reaction, wherein M is reduced
by a granular or powdered metal present in the reaction
mixture.
[0103] The active materials of the present invention can also be
synthesized via a solid state reaction, with or without
simultaneous oxidation or reduction of those elements in the
compound that are redox active, by heating the requisite starting
materials at an elevated temperature for a given period of time,
until the desired reaction product forms. In a solid-state
reaction, the starting materials are provided in powder or
particulate form, and are mixed together by any of a variety of
procedures, such as by ball milling, blending in a mortar and
pestle, and the like. Thereafter, the mixture of powdered starting
materials may be compressed into a pellet and/or held together with
a binder (which may also serve as a source of reducing agent)
material to form a closely cohering reaction mixture. The reaction
mixture is heated in an oven, generally at a temperature of about
400.degree. C. or greater, until a reaction product forms.
[0104] The reaction may be carried out under reducing or oxidizing
conditions, to reduce the oxidation state of M or to maintain the
oxidation state of the M moiety. Reducing conditions may be
provided by performing the reaction in a "reducing atmosphere" such
as hydrogen, ammonia, carbon monoxide, methane, mixtures of
thereof, or other suitable reducing gas. Reduction conditions may
also be provided by conducting the reaction under low oxygen
partial pressures. Alternatively or in addition thereto, the
reduction may be carried out in situ by including in the reaction
mixture a reductant that will participate in the reaction to reduce
M, but that will produce by-products that will not interfere with
the active material when used later in an electrode or an
electrochemical cell.
[0105] In one embodiment, the reductant is elemental carbon,
wherein the reducing power is provided by simultaneous oxidation of
carbon to carbon monoxide and/or carbon dioxide. An excess of
carbon, remaining after the reaction, is intimately mixed with the
product active material and functions as a conductive constituent
in the ultimate electrode formulation. Accordingly, excess carbon,
on the order of 100% or greater, may be used. The presence of
carbon particles in the starting materials also provides nucleation
sites for the production of the product crystals.
[0106] The source of reducing carbon may also be provided by an
organic material that forms a carbon-rich decomposition product,
referred to herein as a "carbonaceous material," and other
by-products upon heating under the conditions of the reaction. At
least a portion of the organic precursor, carbonaceous material
and/or by-products formed functions as a reductant during the
synthesis reaction for the active material, before, during and/or
after the organic precursor undergoes thermal decomposition. Such
precursors include any liquid or solid organic material (e.g.
sugars and other carbohydrates, including derivatives and polymers
thereof, acetates and acrylates).
[0107] Although the reaction may be carried out in the presence of
oxygen, the reaction is preferably conducted under an essentially
non-oxidizing atmosphere so as not to interfere with the reduction
reactions taking place. An essentially non-oxidizing atmosphere can
be achieved through the use of vacuum, or through the use of inert
gases such as argon and the like.
[0108] Preferably, the particulate starting materials are heated to
a temperature below the melting point of the starting materials.
The temperature should be about 400.degree. C. or greater, and
desirably about 450.degree. C. or greater. CO and/or CO.sub.2
evolve during the reaction. Higher temperatures favor CO formation.
Some of the reactions are more desirably conducted at temperatures
greater than about 600.degree. C.; most desirably greater than
about 650.degree. C. Suitable ranges for many reactions are from
about 500.degree. C. to about 1200.degree. C.
[0109] At about 700.degree. C. both the C.fwdarw.CO and the
C.fwdarw.CO.sub.2 reactions are occurring. At closer to about
600.degree. C. the C.fwdarw.CO.sub.2 reaction is the dominant
reaction. At closer to about 800.degree. C. the C.fwdarw.CO
reaction is dominant. Since the reducing effect of the
C.fwdarw.CO.sub.2 reaction is greater, the result is that less
carbon is needed per atomic unit of metal to be reduced. CO
produced during the C.fwdarw.CO reaction may be further involved in
the reduction reaction via the CO.fwdarw.CO.sub.2 reaction.
[0110] The starting materials may be heated at ramp rates from a
fraction of a degree up to about 10.degree. C. per minute. Once the
desired reaction temperature is attained, the reactants (starting
materials) are held at the reaction temperature for a time
sufficient for the reaction to occur. Typically, the reaction is
carried out for several hours at the final reaction
temperature.
[0111] After reaction, the products are preferably cooled from the
elevated temperature to ambient (room) temperature (i.e., about
10.degree. C. to about 40.degree. C.). It is also possible to
quench the products to achieve a higher cooling rate, for example
on the order of about 100.degree. C./minute. The thermodynamic
considerations such as ease of reduction of the selected starting
materials, the reaction kinetics, and the melting point of the
salts will cause adjustment in the general procedure, such as the
amount of reducing agent, the temperature of the reaction, and the
dwell time.
Electrochemical Cells:
[0112] To form an electrode, the active material of the present
invention may be combined with a polymeric binder in order to form
a cohesive mixture. The mixture this then placed in electrical
communication with a current collector which, in turn, provides
electrical communication between the electrode and an external
load. The mixture may be formed or laminated onto the current
collector, or an electrode film may be formed from the mixture
wherein the current collector is embedded in the film. Suitable
current collectors include reticulated or foiled metals (e.g.
aluminum, copper and the like). An electrically conductive agent
(e.g. carbon and the like) may be added to the mixture so as to
increase the electrical conductivity of the electrode. In one
embodiment, the electrode material is pressed onto or about the
current collector, thus eliminating the need for the polymeric
binder.
[0113] To form an electrochemical cell, a solid electrolyte or an
electrolyte-permeable separator is interposed between the electrode
and a counter-electrode. In one embodiment, the counter-electrode
contains an intercalation active material selected from the group
consisting of a transition metal oxide, a metal chalcogenide,
carbon (e.g. graphite), and mixtures thereof. Counter electrodes,
electrolyte compositions, and methods for making the same, among
those useful herein, are described in U.S. Ser. No. 10/323,457,
filed Dec. 18, 2002; U.S. Pat. No. 5,700,298, Shi et al., issued
Dec. 23, 1997; U.S. Pat. No. 5,830,602, Barker et al., issued Nov.
3, 1998; U.S. Pat. No. 5,418,091, Gozdz et al., issued May 23,
1995; U.S. Pat. No. 5,508,130, Golovin, issued Apr. 16, 1996; U.S.
Pat. No. 5,541,020, Golovin et al., issued Jul. 30, 1996; U.S. Pat.
No. 5,620,810, Golovin et al., issued Apr. 15, 1997; U.S. Pat. No.
5,643,695, Barker et al., issued Jul. 1, 1997; U.S. Pat. No.
5,712,059, Barker et al., issued Jan. 27, 1997; U.S. Pat. No.
5,851,504, Barker et al., issued Dec. 22, 1998; U.S. Pat. No.
6,020,087, Gao, issued Feb. 1, 2001; and U.S. Pat. No. 6,103,419,
Saidi et al., issued Aug. 15, 2000; all of which are incorporated
by reference herein.
[0114] Electrochemical cells composed of electrodes, electrolytes
and other materials, among those useful herein, are described in
the following documents, all of which are incorporated by reference
herein: U.S. Pat. No. 4,668,595, Yoshino et al., issued May 26,
1987; U.S. Pat. No. 4,792,504, Schwab et al., issued Dec. 20, 1988;
U.S. Pat. No. 4,830,939, Lee et al., issued May 16, 1989; U.S. Pat.
No. 4,935,317, Fauteaux et al., issued Jun. 19, 1980; U.S. Pat. No.
4,990,413, Lee et al., issued Feb. 5, 1991; U.S. Pat. No.
5,037,712, Shackle et al., issued Aug. 6, 1991; U.S. Pat. No.
5,262,253, Golovin, issued Nov. 16, 1993; U.S. Pat. No. 5,300,373,
Shackle, issued Apr. 5, 1994; U.S. Pat. No. 5,399,447,
Chaloner-Gill, et al., issued Mar. 21, 1995; U.S. Pat. No.
5,411,820, Chaloner-Gill, issued May 2, 1995; U.S. Pat. No.
5,435,054, Tonder et al., issued Jul. 25, 1995; U.S. Pat. No.
5,463,179, Chaloner-Gill et al., issued Oct. 31, 1995; U.S. Pat.
No. 5,482,795, Chaloner-Gill., issued Jan. 9, 1996; U.S. Pat. No.
5,660,948, Barker, issued Sep. 16, 1995; and U.S. Pat. No.
6,306,215, Larkin, issued Oct. 23, 2001.
Synthesis and Characterization of Active Materials:
[0115] The following non-limiting examples illustrate the
compositions and methods of the present invention.
EXAMPLE 1
Reaction A--Synthesis of Li.sub.aNb.sub.bMnPO.sub.4
[0116]
LiH.sub.2PO.sub.4+Mn(CH.sub.3CO.sub.2).sub.24H.sub.2O+Nb.sub.2O.su-
b.5+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aNb.sub.bMnPO.sub.4
(A)
[0117] Li.sub.aNb.sub.bMnPO.sub.4 active material synthesized per
reaction A is accomplished by first combining the reactants, and
then ball milling the same to mix the particles. Thereafter, the
particle mixture is pelletized. The pelletized mixture is heated
for about 4 hours at about 700.degree. C. in an oven in a flowing
inert atmosphere (e.g. argon). Thereafter, the sample is cooled and
then removed from the oven. To synthesize active material with no
residual carbon (which is present due to the pyrolization of any
organic material present in the reaction mixture), a high flow-rate
inert atmosphere or partially oxidizing atmosphere is employed.
[0118] Several compounds having the general formula
Li.sub.aNb.sub.bMnPO.sub.4 were synthesized per reaction A. Because
these compounds exhibited low electrical conductivity,
electrochemical performance data could not be obtained
experimentally. Table 1 below summarizes the reactants employed and
their respective amounts for each compound synthesized. In each
example herein below, the weight in grams of each reactant was
adjusted to account for impurities present in the particular
reactant. TABLE-US-00001 TABLE 1 Sample LiH.sub.2PO.sub.4
Mn(CH.sub.3CO.sub.2).sub.2.4H.sub.2O Nb.sub.2O.sub.5
NH.sub.4H.sub.2PO.sub.4 No. 103.93 g/mol 245.09 g/mol 265.81 g/mol
115.03 g/mol Li.sub.aNb.sub.bMnPO.sub.4 1 0.99 mol 1 mol 0.001 mol
0.01 mol a = 0.99 b = 0.002 2 0.98 mol 1 mol 0.002 mol 0.02 mol a =
0.98 b = 0.004 3 0.97 mol 1 mol 0.003 mol 0.03 mol a = 0.97 b =
0.006 4 0.96 mol 1 mol 0.004 mol 0.04 mol a = 0.96 b = 0.008
EXAMPLE 2
Reaction B--Synthesis of Li.sub.aMg.sub.bMn.sub.cPO.sub.4
[0119]
LiH.sub.2PO.sub.4+Mn(CH.sub.3CO.sub.2).sub.24H.sub.2O+Mg(CH.sub.3C-
O.sub.2).sub.24H.sub.2O+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aMg.sub.bMn.-
sub.cPO.sub.4 (B)
[0120] Several compounds having the general formula
Li.sub.aMg.sub.bMn.sub.cPO.sub.4 were synthesized per reaction B,
per the reaction conditions of Example 1. Because these compounds
exhibited low electrical conductivity, electrochemical performance
data could not be obtained experimentally. Table 2 below summarizes
the reactants employed and their respective amounts for each
compound synthesized. TABLE-US-00002 TABLE 2 Sample
LiH.sub.2PO.sub.4 Mn(CH.sub.3CO.sub.2).sub.2.4H.sub.2O
Mg(CH.sub.3CO.sub.2).sub.2.4H.sub.2O NH.sub.4H.sub.2PO.sub.4 No.
103.93 g/mol 245.09 g/mol 214.46 g/mol 115.03 g/mol
Li.sub.aMg.sub.bMn.sub.cPO.sub.4 1 0.98 mol 1 mol 0.01 mol 0.02 mol
a = 0.98 b = 0.01, c = 1 2 0.96 mol 1 mol 0.02 mol 0.04 mol a =
0.96 b = 0.02, c = 1 3 0.94 mol 1 mol 0.03 mol 0.06 mol a = 0.94 b
= 0.03, c = 1 4 0.96 mol 1 mol 0.05 mol 0.02 mol a = 0.98, b =
0.05, c = 0.96
EXAMPLE 3
Reaction C--Synthesis of Li.sub.aZr.sub.bMnPO.sub.4
[0121]
LiH.sub.2PO.sub.4+Zr(OC.sub.2H.sub.5).sub.4+Mn(CH.sub.3CO.sub.2).s-
ub.24H.sub.2O+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aZr.sub.bMnPO.sub.4
(C)
[0122] Several compounds having the general formula
Li.sub.aZr.sub.bMnPO.sub.4 were synthesized per reaction C, per the
reaction conditions of Example 1. Because these compounds exhibited
low electrical conductivity, electrochemical performance data could
not be obtained experimentally. Table 3 below summarizes the
reactants employed and their respective amounts for each compound
synthesized. TABLE-US-00003 TABLE 3 Sample LiH.sub.2PO.sub.4
Zr(OC.sub.2H.sub.5).sub.4 Mn(CH.sub.3CO.sub.2).sub.2.4H.sub.2O
NH.sub.4H.sub.2PO.sub.4 No. 103.93 g/mol 271.41 g/mol 245.09 g/mol
115.03 g/mol Li.sub.aZr.sub.bMnPO.sub.4 1 0.98 mol 0.005 mol 1 mol
0.02 mol a = 0.98 b = 0.005 2 0.96 mol 0.01 mol 1 mol 0.04 mol a =
0.96 b = 0.01
EXAMPLE 4
Reaction D--Synthesis of
Li.sub.aZr.sub.bV.sub.2(PO.sub.4).sub.3
[0123]
LiH.sub.2PO.sub.4+Zr(OC.sub.2H.sub.5).sub.4+V.sub.2O.sub.3+NH.sub.-
4H.sub.2PO.sub.4.fwdarw.Li.sub.aZr.sub.bV.sub.2(PO.sub.4).sub.3
(D)
[0124] Several compounds having the general formula
Li.sub.aZr.sub.bV.sub.2(PO.sub.4).sub.3 were synthesized per
reaction D, per the reaction conditions of Example 1. Table 4 below
summarizes the reactants employed and their respective amounts for
each compound synthesized. TABLE-US-00004 TABLE 4 LiH.sub.2PO.sub.4
V.sub.2O.sub.3 Sample 103.93 Zr(OC.sub.2H.sub.5).sub.4 149.88
NH.sub.4H.sub.2PO.sub.4 No. g/mol 271.41 g/mol g/mol 115.03 g/mol
Li.sub.aZr.sub.bV.sub.2PO.sub.4 1 2.98 mol 0.005 mol 1 mol 0.02 mol
a = 2.98 b = 0.005 2 2.94 mol 0.01 mol 1 mol 0.06 mol a = 2.96 b =
0.01 3 2.9 mol 0.025 mol 1 mol 0.1 mol a = 2.90 b = 0.025 4 2.8 mol
0.05 mol 1 mol 0.2 mol a = 2.80 b = 0.05
EXAMPLE 5
Reaction E--Synthesis of
Li.sub.aNb.sub.bV.sub.2(PO.sub.4).sub.3
[0125]
LiH.sub.2PO.sub.4+Nb.sub.2O.sub.5+V.sub.2O.sub.3+NH.sub.4H.sub.2PO-
.sub.4.fwdarw.Li.sub.aNb.sub.bV.sub.2(PO.sub.4).sub.3 (E)
[0126] Several compounds having the general formula
Li.sub.aNb.sub.bV.sub.2(PO.sub.4).sub.3 were synthesized per
reaction E, per the reaction conditions of Example 1. Table 5 below
summarizes the reactants employed and their respective amounts for
each compound synthesized. TABLE-US-00005 TABLE 5 Sam-
LiH.sub.2PO.sub.4 Nb.sub.2O.sub.5 V.sub.2O.sub.3
NH.sub.4H.sub.2PO.sub.4 ple 103.93 265.81 149.88 115.03 No. g/mol
g/mol g/mol g/mol Li.sub.aNb.sub.bV.sub.2(PO.sub.4).sub.3 1 2.99
mol 0.001 mol 1 mol 0.01 mol a = 2.99 b = 0.002 2 2.98 mol 0.002
mol 1 mol 0.02 mol a = 2.98 b = 0.004 3 2.97 mol 0.003 mol 1 mol
0.03 mol a = 2.97 b = 0.006 4 2.96 mol 0.004 mol 1 mol 0.04 mol a =
2.96 b = 0.008 5 2.95 mol 0.005 mol 1 mol 0.05 mol a = 2.95 b =
0.01
EXAMPLE 6
Reaction F--Synthesis of
Li.sub.aMg.sub.bV.sub.2(PO.sub.4).sub.3
[0127]
LiH.sub.2PO.sub.4+Mg(CH.sub.3CO.sub.2).sub.24H.sub.2O+V.sub.2O.sub-
.3+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aMg.sub.bV.sub.2(PO.sub.4).sub.3
(F)
[0128] Several compounds having the general formula
Li.sub.aMg.sub.bV.sub.2(PO.sub.4).sub.3 were synthesized per
reaction F, per the reaction conditions of Example 1. Table 6 below
summarizes the reactants employed and their respective amounts for
each compound synthesized. TABLE-US-00006 TABLE 6 Sample
LiH.sub.2PO.sub.4 Mg(CH.sub.3CO.sub.2).sub.2.4H.sub.2O
V.sub.2O.sub.3 NH.sub.4H.sub.2PO.sub.4 No. 103.93 g/mol 214.46
g/mol 149.88 g/mol 115.03 g/mol
Li.sub.aMg.sub.bV.sub.2(PO.sub.4).sub.3 1 2.98 mol 0.01 mol 1 mol
0.02 mol a = 2.98 b = 0.01 2 2.94 mol 0.03 mol 1 mol 0.06 mol a =
2.94 b = 0.03 3 2.9 mol 0.05 mol 1 mol 0.1 mol a = 2.90 b = 0.05 4
2.8 mol 0.1 mol 1 mol 0.2 mol a = 2.80 b = 0.1
EXAMPLE 7
Reaction G--Synthesis and Characterization of
Li.sub.aZr.sub.bCoPO.sub.4
[0129]
LiH.sub.2PO.sub.4+Zr(OC.sub.2H.sub.5).sub.4+Co.sub.3O.sub.4+NH.sub-
.4H.sub.2PO.sub.4.fwdarw.Li.sub.aZr.sub.bCoPO.sub.4 (G)
[0130] Several compounds having the general formula
Li.sub.aZr.sub.bCoPO.sub.4 were synthesized per reaction G, per the
reaction conditions of Example 1. Table 7 below summarizes the
reactants employed, and their respective amounts, for each compound
synthesized. TABLE-US-00007 TABLE 7 Sam- LiH.sub.2PO.sub.4
Zr(OC.sub.2H.sub.5).sub.4 Co.sub.3O.sub.4 ple 103.93 271.41 240.80
NH.sub.4H.sub.2PO.sub.4 No. g/mol g/mol g/mol 115.03 g/mol
Li.sub.aZr.sub.bCoPO.sub.4 1 1 mol 0.00 mol 0.33 mol 0.00 mol a = 1
2 0.98 mol 0.005 mol 0.33 mol 0.02 mol a = 0.98 b = 0.005 3 0.96
mol 0.01 mol 0.33 mol 0.04 mol a = 0.96 b = 0.01
EXAMPLE 8
Reaction H--Synthesis of Li.sub.aNb.sub.bCoPO.sub.4
[0131]
LiH.sub.2PO.sub.4+Nb.sub.2O.sub.5+Co.sub.3O.sub.4+NH.sub.4H.sub.2P-
O.sub.4.fwdarw.Li.sub.aNb.sub.bCoPO.sub.4 (H)
[0132] Several compounds having the general formula
Li.sub.aNb.sub.bCoPO.sub.4 were synthesized per reaction H, per the
reaction conditions of Example 1. Table 8 below summarizes the
reactants employed, and their respective amounts, for each compound
synthesized. TABLE-US-00008 TABLE 8 Sam- LiH.sub.2PO.sub.4
Nb.sub.2O.sub.5 Co.sub.3O.sub.4 ple 103.93 265.81 240.80
NH.sub.4H.sub.2PO.sub.4 No. g/mol g/mol g/mol 115.03 g/mol
Li.sub.aNb.sub.bCoPO.sub.4 1 0.99 mol 0.001 mol 0.33 mol 0.01 mol a
= 0.99 b = 0.002 2 0.98 mol 0.002 mol 0.33 mol 0.02 mol a = 0.98 b
= 0.004 3 0.97 mol 0.003 mol 0.33 mol 0.03 mol a = 0.97 b = 0.006 4
0.96 mol 0.004 mol 0.32 mol 0.04 mol a = 0.96 b = 0.008
EXAMPLE 9
Reaction I--Synthesis and Characterization of
Li.sub.aMg.sub.bCo.sub.cPO.sub.4
[0133]
LiH.sub.2PO.sub.4+Mg(CH.sub.3CO.sub.2).sub.24H.sub.2O+Co.sub.3O.su-
b.4+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aMg.sub.bCo.sub.cPO.sub.4
(I)
[0134] Several compounds having the general formula
Li.sub.aMg.sub.bCo.sub.cPO.sub.4 were synthesized per reaction I,
per the reaction conditions of Example 1. Table 9 below summarizes
the reactants employed, and their respective amounts, for each
compound synthesized. TABLE-US-00009 TABLE 9 Sample
LiH.sub.2PO.sub.4 MgCH.sub.3CO.sub.2.4H.sub.2O Co.sub.3O.sub.4
NH.sub.4H.sub.2PO.sub.4 No. 103.93 g/mol 214.46 g/mol 240.80 g/mol
115.03 g/mol Li.sub.aMg.sub.bCo.sub.cPO.sub.4 1 0.98 mol 0.01 mol
0.33 mol 0.02 mol a = 0.98 b = 0.01, c = 1 2 0.96 mol 0.02 mol 0.33
mol 0.04 mol a = 0.96 b = 0.02, c = 1 3 0.94 mol 0.03 mol 0.33 mol
0.06 mol a = 0.94 b = 0.03, c = 1 4 0.98 mol 0.05 mol 0.33 mol 0.02
mol a = 0.98, b = 0.05, c = 0.96
[0135] Li.sub.aMg.sub.bCo.sub.cPO.sub.4 active material synthesized
as per Reaction I was black in color, and the measured electrical
conductivity ranged from about 10.sup.-4 S/cm to about 10.sup.-3
S/cm. LiCoPO.sub.4 active material was bright purple in color, and
the electrical conductivity ranged from about 10.sup.-9 S/cm to
about 10.sup.-10 S/cm.
EXAMPLE 10
Reaction J--Synthesis and Characterization of
Li.sub.aZr.sub.bFePO.sub.4
[0136]
LiH.sub.2PO.sub.4+Zr(OC.sub.2H.sub.5).sub.4+FeC.sub.2O.sub.42H.sub-
.2O+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aZr.sub.bFePO.sub.4
(J)
[0137] Several compounds having the general formula
Li.sub.aZr.sub.bFePO.sub.4 were synthesized per reaction J, per the
reaction conditions of Example 1. Table 10 below summarizes the
reactants employed, and their respective amounts, for each compound
synthesized. TABLE-US-00010 TABLE 10 LiH.sub.2PO.sub.4
Zr(OC.sub.2H.sub.5).sub.4 FeC.sub.2O.sub.4.2H.sub.2O
NH.sub.4H.sub.2PO.sub.4 Sam-ple No. 103.93 g/mol 271.41 g/mol
179.90 g/mol 115.03 g/mol Li.sub.aZr.sub.bFePO.sub.4 1 0.98 mol
0.005 mol 1 mol 0.02 mol a = 0.98 b = 0.005 2 0.96 mol 0.01 mol 1
mol 0.04 mol a = 0.96 b = 0.01
EXAMPLE 11
Reaction K--Synthesis and Characterization of
Li.sub.aNb.sub.bFePO.sub.4
[0138]
LiH.sub.2PO.sub.4+Nb.sub.2O.sub.5+FeC.sub.2O.sub.42H.sub.2O+NH.sub-
.4H.sub.2PO.sub.4.fwdarw.Li.sub.aNb.sub.bFePO.sub.4 (K)
[0139] Several compounds having the general formula
Li.sub.aNb.sub.bFePO.sub.4 were synthesized per reaction K, per the
reaction conditions of Example 1. Table 11 below summarizes the
reactants employed, and their respective amounts, for each compound
synthesized. TABLE-US-00011 TABLE 11 LiH.sub.2PO.sub.4
Nb.sub.2O.sub.5 FeC.sub.2O.sub.4.2H.sub.2O NH.sub.4H.sub.2PO.sub.4
Sample No. 103.93 g/mol 265.81 g/mol 179.90 g/mol 115.03 g/mol
Li.sub.aNb.sub.bFePO.sub.4 1 0.99 mol 0.001 mol 1 mol 0.01 mol a =
0.99 b = 0.002 2 0.98 mol 0.002 mol 1 mol 0.02 mol a = 0.98 b =
0.004 3 0.97 mol 0.003 mol 1 mol 0.03 mol a = 0.97 b = 0.006 4 0.96
mol 0.004 mol 1 mol 0.04 mol a = 0.96 b = 0.008
[0140] The weight percent wt % of residual carbon formed upon the
decomposition of the Fe reactant complex, was determined to be
about 1 to 2 weight percent wt % for all the samples 1, 2, 3 and
4.
[0141] The electrical conductivity for a sample of
Li.sub.0.95Nb.sub.0.01FePO.sub.4 and
Li.sub.0.99Nb.sub.0.002FePO.sub.4 synthesized as per reaction J was
determined to be approximately 10.sup.-3 S/cm. The measurements
were repeated for LiFePO.sub.4 prepared per the teachings of
Example 11 herein below, which yielded an electrical conductivity
of approximately 10.sup.-10 S /cm.
EXAMPLE 12
Reaction L--Synthesis and Characterization of
Li.sub.aMg.sub.bFe.sub.cPO.sub.4
[0142]
LiH.sub.2PO.sub.4+FeC.sub.2O.sub.42H.sub.2O+Mg(CH.sub.3CO.sub.2).s-
ub.24H.sub.2O+NH.sub.4H.sub.2PO.sub.4.fwdarw.Li.sub.aMg.sub.bFe.sub.cPO.su-
b.4 (L)
[0143] Several compounds having the general formula
Li.sub.aMg.sub.bFe.sub.cPO.sub.4 were synthesized per reaction L,
per the reaction conditions of Example 1. Table 12 below summarizes
the reactants employed, and their respective amounts, for each
compound synthesized. TABLE-US-00012 TABLE 12 Sample
LiH.sub.2PO.sub.4 Mg(CH.sub.3CO.sub.2).sub.2.4H.sub.2O
FeC.sub.2O.sub.4.2H.sub.2O NH.sub.4H.sub.2PO.sub.4 No. 103.93 g/mol
214.46 g/mol 179.90 g/mol 115.03 g/mol
Li.sub.aMg.sub.bFe.sub.cPO.sub.4 1 1 mol 0.00 mol 1 mol 0.00 mol a
= 1 b = 0, c = 1 2 0.98 mol 0.01 mol 1 mol 0.02 mol a = 0.98 b =
0.01, c = 1 3 1 mol 0.04 mol 1 mol 0.00 mol a = 1, b = 0.04, c =
0.96 4 0.98 mol 0.05 mol 1 mol 0.02 mol a = 0.98, b = 0.05, c =
0.96
[0144] LiFePO.sub.4 active material synthesized as per Reaction L
was green or light gray in color. In contrast,
Li.sub.aMg.sub.bFe.sub.cPO.sub.4 active materials synthesized as
per Reaction L were black in color.
[0145] Reitveld refined CuK.alpha. (.lamda.=1.5405 .ANG. with a
scattering angle of 2.theta.) x-ray diffraction patterns were
collected for the LiFePO.sub.4, Li.sub.0.98Mg.sub.0.01FePO.sub.4,
and Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 active materials, and
are represented in FIG. 1. The patterns shown in FIG. 1 for
Li.sub.0.98Mg.sub.0.01FePO.sub.4 and
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 show that these materials
are single phase materials, as is LiFePO.sub.4. Table 13 below
shows the unit cell dimensions and volumes obtained for the three
active materials. TABLE-US-00013 TABLE 13 Active Material a ({acute
over (.ANG.)}) b ({acute over (.ANG.)}) c ({acute over (.ANG.)})
Volume ({acute over (.ANG.)}) LiFePO.sub.4 10.3245 6.0088 4.6958
291.3168 Li.sub.0.98Mg.sub.0.01FePO.sub.4 10.3158 6.0021 4.6932
290.5872 Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 10.3099 5.9983
4.6920 290.1591
Electrochemical Performance of Active Material:
[0146] For several samples identified above, electrochemical cells
were prepared as follows. To test the electrochemical performance
of pure active material and eliminate the effect of carbon and
binder, the as-synthesized powder (first passed through 53 micron
screen) is wetted with a suitable volatile solvent (e.g. acetone),
sprayed on Al disk and then pressed under 50,000 pounds per square
inch (psi) pressure for 10 minutes. The active powder adheres to
the Al current collector to form a stable disk cathode electrode.
There are no carbon additives or polymeric binder in the disk
cathode electrode.
[0147] In some of the examples herein below, in order to test the
electrochemical performance of active materials in a regular cell
configuration, the as-synthesized powder (first passed through 53
micron screen) is mixed with conductive carbon black (4 wt %) and
poly(vinylidene difluoride) (PVdF) (10 wt %) solution in acetone,
and cast onto an Al current collector to form stable film cathode
electrode.
[0148] Lithium metal foil is employed as the anode. The electrolyte
includes ethylene carbonate (EC) and ethyl methyl carbonate (EMC)
in a weight ratio of 2:1, and a 1 molar concentration of LiPF.sub.6
salt. A glass fiber separator interpenetrated by the solvent and
the salt is interposed between the cathode and the anode. In each
of the examples described herein, the electrochemical cell is
cycled using constant current cycling at .+-.0.2 milliamps per
square centimeter (mA/cm.sup.2) in a range of 3 to 5 volts (V) at a
temperature of about 23.degree. C., at varying rates.
[0149] An electrochemical cell constructed using a disk cathode
containing LiCoPO.sub.4 synthesized per the teaching of Example 7
(0% binder, 0% carbon, 100% LiCoPO.sub.4 synthesized in a high
flow-rate inert atmosphere), was cycled per the conditions stated
above. FIG. 2 is a voltage profile (voltage as a function of time)
for the cell. As the profile in FIG. 2 indicates, the cell
exhibited almost no capacity, which is attributed to the high
electrical resistivity of the active material. An electrochemical
cell constructed using a disk cathode containing
Li.sub.0.98Mg.sub.0.05Co.sub.0.96PO.sub.4 (0% binder, 0% carbon)
was cycled per the conditions stated above. FIG. 3 is a voltage
profile for the cell. As the profile in FIG. 3, indicates,
LiCoPO.sub.4 doped with Mg exhibited a significantly greater amount
of capacity than undoped LiCoPO.sub.4, even in the absence of
carbon. Table 14 below shows the charge capacity (Q.sub.c) and
discharge capacity (Q.sub.d) for the active material contained in
each electrochemical cell, as well as the corresponding capacity
loss for each cycle. TABLE-US-00014 TABLE 14 Active Material and
Cycle Capacity Theoretical Capacity No. Q.sub.c (mAh/g) Q.sub.d
(mAh/g) Loss (%) LiCoPO.sub.4 1 1.250 0.162 87.1 166.66 mAh/g 2
0.125 0.074 40.5 3 0.055 0.040 27.9 4 0.043 0.030 30.7 5 0.031
0.022 29.4 Li.sub.0.98Mg.sub.0.05Co.sub.0.96PO.sub.4 1 151.0 78.2
48.2 161.3 mAh/g 2 77.7 62.4 19.6 3 63.9 51.4 19.6 4 51.8 41.4 20.0
5 39.6 31.8 19.7
[0150] An electrochemical cell constructed using a disk cathode
containing LiFePO.sub.4 synthesized per the teaching of Example 12
using a high flow-rate inert atmosphere (0% binder, 0% carbon, 100%
LiFePO.sub.4), was cycled per the conditions stated above. FIG. 4
is a voltage profile (voltage as a function of time) for the cell.
As the profile in FIG. 4 indicates, the cell exhibited almost no
capacity, which is attributed to the high electrical resistivity of
the active material.
[0151] Electrochemical cells constructed using a disk cathode
containing Li.sub.0.98Mg.sub.0.01FePO.sub.4,
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4, and
Li.sub.0.99Nb.sub.0.002FePO.sub.4 (0% binder, 0% carbon) were
cycled per the conditions stated above. FIGS. 5, 6 and 7 are
voltage profiles for the cells. As the profiles in FIGS. 5, 6 and 7
indicate, LiFePO.sub.4 doped with Mg or Nb exhibited a
significantly greater amount of capacity than undoped LiFePO.sub.4,
even in the absence of carbon. Table 14 below shows the charge
capacity (Q.sub.c) and discharge capacity (Q.sub.d) for the active
material contained in each electrochemical cell, as well as the
corresponding capacity loss for each cycle. As Table 15 indicates,
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 active material (wherein
the amount of Fe and Li are each dependent (reduced by) the amount
of Mg dopant) exhibited superior performance, and high capacity.
TABLE-US-00015 TABLE 15 Active Material and Cycle Capacity
Theoretical Capacity No. Q.sub.c (mAh/g) Q.sub.d (mAh/g) Loss (%)
LiFePO.sub.4 1 0.68 0.00077 99.89 169.9 mAh/g 2 0.03 0.00064 97.67
3 0.02 0.00064 96.69 4 0.02 0.00061 96.03 5 0.01 0.00064 95.68
Li.sub.0.98Mg.sub.0.01FePO.sub.4 1 130.35 100.57 22.85 166.4 mAh/g
2 107.22 102.56 4.35 3 114.80 102.16 11.01 4 107.36 100.53 6.36 5
105.86 99.25 6.24 Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 1 149.6
148.4 0.9 164.3 mAh/g 2 155.6 146.5 5.8 3 159.5 145.5 8.8 4 163.8
144.0 12.1 5 161.6 137.0 15.2 Li.sub.0.98Nb.sub.0.002FePO.sub.4 1
133.62 98.28 26.45 2 100.18 100.18 0.00 3 100.80 99.02 1.77 4
100.12 98.65 1.47 5 95.09 93.05 2.15
[0152] An electrochemical cell constructed using a disk cathode
containing LiFePO.sub.4 synthesized per the teaching of Example 12
using a low flow-rate inert atmosphere, was cycled per the
conditions stated above. The reaction product contained
approximately 2.18 wt % residual carbon. FIG. 8 is a voltage
profile (voltage as a function of time) for the cell. As the
profile in FIG. 8 indicates, the carbon-containing LiFePO.sub.4
exhibited enhanced capacity and reduced fade as compared to the
carbon-deficient counterpart.
[0153] Electrochemical cells constructed using a disk cathode
containing Li.sub.0.98Mg.sub.0.01FePO.sub.4,
LiMg.sub.0.04Fe.sub.0.96PO.sub.4,
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4, each synthesized per the
teachings of Example 12 using a low flow-rate inert atmosphere,
were cycled per the conditions stated above. The reaction products
contained approximately 1.88 wt %, 2.24 wt % and 1.98 wt % residual
carbon, respectively. FIGS. 9, 10 and 11 are voltage profiles for
the cells. As the profiles in FIGS. 9, 10 and 11 indicate, residual
carbon-containing LiFePO.sub.4 doped with Mg exhibited a
significantly enhanced capacity and reduced fade as compared to the
carbon-deficient counterparts. Table 16 below shows the charge
capacity (Q.sub.c) and discharge capacity (Q.sub.d) for the active
material contained in each electrochemical cell, as well as the
corresponding capacity loss for each cycle. As Table 15 indicates,
residual carbon-containing
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 active material (wherein
the amount of Fe and Li are each dependent (reduced by) the amount
of Mg dopant) exhibited superior performance, and high capacity.
TABLE-US-00016 TABLE 16 Active Material/C Capacity wt %/Theoretical
Cycle Loss Capacity No. Q.sub.c (mAh/g) Q.sub.d (mAh/g) (%)
LiFePO.sub.4 1 156.4 146.9 6.1 (2.18% C) 2 156.4 147.7 5.6 169.9
mAh/g 3 154.1 145.8 5.4 4 150.7 144.6 4.0 5 149.9 143.9 4.0
Li.sub.0.98Mg.sub.0.01FePO.sub.4 1 155.1 143.5 7.5 1.88% C 2 148.5
141.6 4.6 166.4 mAh/g 3 146.0 142.1 2.6 4 146.0 139.9 4.2 5 144.6
139.4 3.6 LiMg.sub.0.04Fe.sub.0.96PO.sub.4 1 148.1 133.5 9.8 2.24%
C 2 135.5 130.2 4.0 164.8 mAh/g 3 134.8 130.2 3.4 4 132.9 127.4 4.1
5 129.8 124.3 4.2 Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 1 159.2
152.3 4.4 1.98% C 2 156.0 153.1 1.8 164.3 mAh/g 3 155.8 151.5 2.8 4
155.8 151.7 2.6 5 154.8 151.3 2.3
[0154] An electrochemical cell constructed using a film cathode
containing Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 (86% active
material, 4% carbon, 10% binder) synthesized per the teaching of
Example 12 using a high flow-rate inert atmosphere, was cycled per
the conditions stated above. The carbon/binder-containing
Li.sub.0.98Mg.sub.0.05Fe.sub.0.96PO.sub.4 active material exhibited
excellent capacity and reduced fade. Table 17 below shows the
average charge capacity (Q.sub.c) and discharge capacity (Q.sub.d)
for the active material contained in the five electrochemical
cells, as well as the corresponding capacity loss for each cycle.
TABLE-US-00017 TABLE 17 Cycle Capacity Loss No. Q.sub.c (mAh/g)
Q.sub.d (mAh/g) (%) 1 156.9 145.1 8.38 2 151.1 144.3 4.5 3 150.1
144.6 3.7 4 149.6 144.8 3.21 5 149.6 144.8 2.55 35 152.5 145.7
4.46
[0155] The examples and other embodiments described herein are
exemplary and not intended to be limiting in describing the full
scope of compositions and methods of this invention. Equivalent
changes, modifications and variations of specific embodiments,
materials, compositions and methods may be made within the scope of
the present invention, with substantially similar results.
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