U.S. patent application number 13/410895 was filed with the patent office on 2012-08-02 for amorphous ionically conductive metal oxides and sol gel method of preparation.
This patent application is currently assigned to JOHNSON IP HOLDING, LLC. Invention is credited to Lazbourne Alanzo ALLIE, Davorin BABIC, Adrian M. GRANT, David Ketema JOHNSON, Lonnie G. JOHNSON, Stanley JONES, William RAUCH.
Application Number | 20120196189 13/410895 |
Document ID | / |
Family ID | 46577618 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120196189 |
Kind Code |
A1 |
BABIC; Davorin ; et
al. |
August 2, 2012 |
AMORPHOUS IONICALLY CONDUCTIVE METAL OXIDES AND SOL GEL METHOD OF
PREPARATION
Abstract
Amorphous lithium lanthanum zirconium oxide (LLZO) is formed as
an ionically-conductive electrolyte medium. The LLZO comprises by
percentage of total number of atoms from about 0.1% to about 50%
lithium, from about 0.1% to about 25% lanthanum, from about 0.1% to
about 25% zirconium, from about 30% to about 70% oxygen and from
0.0% to about 25% carbon. At least one layer of amorphous LLZO may
be formed through a sol-gel process wherein quantities of lanthanum
methoxyethoxide, lithium butoxide and zirconium butoxide are
dissolved in an alcohol-based solvent to form a mixture which is
dispensed into a substantially planar configuration, transitioned
through a gel phase, dried and cured to a substantially dry
phase.
Inventors: |
BABIC; Davorin; (Marietta,
GA) ; JOHNSON; Lonnie G.; (Atlanta, GA) ;
RAUCH; William; (Douglasville, GA) ; JOHNSON; David
Ketema; (Smyrna, GA) ; JONES; Stanley; (Forest
Park, GA) ; ALLIE; Lazbourne Alanzo; (McDonough,
GA) ; GRANT; Adrian M.; (Loganville, GA) |
Assignee: |
JOHNSON IP HOLDING, LLC
Atlanta
GA
|
Family ID: |
46577618 |
Appl. No.: |
13/410895 |
Filed: |
March 2, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12848991 |
Aug 2, 2010 |
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13410895 |
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12163044 |
Jun 27, 2008 |
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12848991 |
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60947016 |
Jun 29, 2007 |
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Current U.S.
Class: |
429/319 ;
427/126.1; 429/321; 429/322 |
Current CPC
Class: |
H01M 2300/0071 20130101;
C04B 35/624 20130101; H01M 10/0525 20130101; C04B 2235/3251
20130101; H01M 10/052 20130101; C04B 2235/441 20130101; Y02E 60/10
20130101; C04B 2235/3215 20130101; C04B 35/6269 20130101; C04B
2235/44 20130101; C04B 35/63444 20130101; C04B 2235/3217 20130101;
C04B 35/486 20130101; C04B 2235/3227 20130101; C04B 35/6264
20130101; C04B 35/632 20130101; C04B 2235/3203 20130101; H01M
10/0562 20130101; H01M 2300/0068 20130101 |
Class at
Publication: |
429/319 ;
429/321; 429/322; 427/126.1 |
International
Class: |
H01M 10/0562 20100101
H01M010/0562; B05D 5/12 20060101 B05D005/12; H01M 10/02 20060101
H01M010/02 |
Claims
1. An amorphous oxide-based compound having a general formula
MwM'xM''yM'''z, wherein M comprises at least one alkali metal, M'
comprises at least one element selected from the group consisting
of barium, strontium, calcium, indium, magnesium, yttrium,
scandium, chromium, aluminum, alkali metals, and lanthanides, M''
comprises at least one element selected from the group consisting
of zirconium, tantalum, niobium, antimony, tin, hafnium, bismuth,
tungsten, silicon, selenium, gallium and germanium, and M'''
comprises oxygen and optionally at least one element selected from
the group consisting of sulfur, selenium, and halogens, wherein w,
x, y, and z are positive numbers, including various combinations of
integers and fractions or decimals.
2. The amorphous oxide-based compound of claim 1, wherein M
comprises lithium, M' comprises lanthanum, M'' comprises zirconium,
and M''' comprises oxygen.
3. The amorphous oxide-based compound of claim 1, wherein by
percentage of total number of atoms M comprises from about 0.1% to
about 50%, M' comprises from about 0.1% to about 25%, M'' comprises
from about 0.1% to about 25%, and M''' comprises from about 30% to
about 70%.
4. The amorphous oxide-based compound of claim 1, having a
substantially planar configuration for an electrolyte medium.
5. An electrolyte medium comprising at least one layer of amorphous
lithium lanthanum zirconium oxide.
6. The electrolyte medium of claim 5, wherein said amorphous
lithium lanthanum zirconium oxide comprises by percentage of total
number of atoms from about 0.1% to about 50% lithium, from about
0.1% to about 25% lanthanum, from about 0.1% to about 25%
zirconium, from about 30% to about 70% oxygen and from 0.0% to
about 25% carbon.
7. A sol gel method for synthesizing an amorphous oxide-based
compound comprising: producing a mixture by substantially
dissolving in a solvent, a first precursor solute comprising an
alkali-metal compound, a second precursor solute comprising a
compound of at least one of barium, strontium, calcium, indium,
magnesium, yttrium, scandium, chromium, aluminum, an alkali-metal
and a lanthanide, a third precursor solute comprising a compound of
at least one of zirconium, tantalum, niobium, antimony, tin,
hafnium, bismuth, tungsten, silicon, selenium, gallium and
germanium, and optionally a fourth precursor solute comprising a
compound of at least one of oxygen, sulfur, selenium, and a
halogen; and dispensing said mixture in a substantially planar
configuration, transitioning through a gel phase, and drying and
curing to a substantially dry phase.
8. A method of synthesizing amorphous lithium lanthanum zirconium
oxide comprising: producing a mixture by substantially dissolving
in a solvent a first precursor solute comprising a compound of
lithium, a second precursor solute comprising a compound of
lanthanum, and a third precursor solute comprising a compound of
zirconium; and dispensing said mixture in a substantially planar
configuration and drying and curing to a substantially dry
phase.
9. The method of claim 8, wherein said solvent comprises an
alcohol-based solvent, said first precursor solute comprises
lithium alkoxide, said second precursor solute comprises lanthanum
alkoxide, and said third precursor solute comprises zirconium
alkoxide.
10. The method of claim 9, wherein said alcohol-based solvent
comprises methoxyethanol.
11. The method of claim 9, wherein said lithium alkoxide comprises
lithium butoxide, said lanthanum alkoxide comprises lanthanum
methoxyethoxide, and said zirconium alkoxide comprises zirconium
butoxide.
12. The method of claim 11, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide.
13. The method of claim 11, wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
14. The method of claim 8, wherein said mixture is dispensed into a
substantially planar configuration by one of spin coating, casting,
dip coating, spray coating, screen printing and ink-jet
printing.
15. The method of claim 11, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide; and wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
16. The method of claim 8, wherein the mixture further comprises a
polymer.
17. The method of claim 16, wherein said solvent comprises an
alcohol-based solvent, said first precursor solute comprises
lithium alkoxide, said second precursor solute comprises lanthanum
alkoxide, and said third precursor solute comprises zirconium
alkoxide.
18. The method of claim 17, wherein said alcohol-based solvent
comprises methoxyethanol and said polymer comprises polyvinyl
pyrrolidone.
19. The method of claim 17, wherein said lithium alkoxide comprises
lithium butoxide, said lanthanum alkoxide comprises lanthanum
methoxyethoxide, and said zirconium alkoxide comprises zirconium
butoxide.
20. The method of claim 19, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide.
21. The method of claim 19, wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
22. The method of claim 16, wherein said polymer comprises an
amount of said polymer pre-dissolved in an amount of said
alcohol-based solvent to produce a polymer solution.
23. The method of claim 7, wherein said mixture is dispensed into a
substantially planar configuration by one of spin coating, casting,
dip coating, spray coating, screen printing and ink-jet
printing.
24. The method of claim 19, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide; wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight said zirconium butoxide; and wherein
said polymer comprises an amount of said polymer pre-dissolved in
an amount of said alcohol-based solvent to produce a polymer
solution.
25. The method of claim 24, wherein said alcohol-based solvent
comprises methoxyethanol and said polymer comprises polyvinyl
pyrrolidone.
26. The method of claim 7, wherein the step of drying and curing
said mixture comprises exposing and heating said mixture in an
environment comprising air and ozone, wherein a concentration of
said ozone in said air is greater than 0.05 parts per million.
27. The method of claim 26, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; and then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes.
28. The method of claim 27, wherein the steps of exposing and
heating said mixture in an environment comprising air and ozone are
followed by the step of heating said mixture in air.
29. The method of claim 28, wherein the step of drying and curing
said mixture further comprises heating said mixture in air at about
300.degree. C. for about 30 minutes.
30. The method of claim 7, wherein the step of drying and curing
said mixture comprises exposing and heating said mixture in an
environment comprising air and ozone, wherein a concentration of
said ozone in said air is greater than 0.05 parts per million.
31. The method of claim 30, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; and then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes.
32. The method of claim 30, wherein the steps of exposing and
heating said mixture in an environment comprising air and ozone are
followed by the step of heating said mixture in air.
33. The method of claim 32, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes; and then heating said
mixture in air at about 300.degree. C. for about 30 minutes.
34. The method of claim 16, wherein the step of drying and curing
said mixture comprises exposing and heating said mixture in an
environment comprising air and ozone, wherein a concentration of
said ozone in said air is greater than 0.05 parts per million.
35. The method of claim 34, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; and then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes.
36. The method of claim 34, wherein the steps of exposing and
heating said mixture in an environment comprising air and ozone are
followed by the step of heating said mixture in air.
37. The method of claim 36, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes; and then heating said
mixture in air at about 300.degree. C. for about 30 minutes.
38. An amorphous oxide-based compound having a general formula
MwCM'xM''yM'''z, wherein C comprises carbon, M comprises at least
one alkali metal, M' comprises at least one element selected from
the group consisting of barium, strontium, calcium, indium,
magnesium, yttrium, scandium, chromium, aluminum, alkali metals,
and lanthanides, M'' comprises at least one element selected from
the group consisting of zirconium, tantalum, niobium, antimony,
tin, hafnium, bismuth, tungsten, silicon, selenium, gallium and
germanium, and M''' comprises oxygen and optionally at least one
element selected from the group consisting of sulfur, selenium, and
halogens, wherein w, x, y, and z are positive numbers, including
various combinations of integers and fractions or decimals.
39. The amorphous oxide-based compound of claim 38, wherein M
comprises lithium, M' comprises lanthanum, M'' comprises zirconium
and M''' comprises oxygen.
40. The amorphous oxide-based compound of claim 38, wherein by
percentage of total number of atoms M comprises from about 0.1% to
about 50%, carbon comprises up to about 25%, M' comprises from
about 0.1% to about 25%, M'' comprises from about 0.1% to about
25%, and M''' comprises from about 30% to about 70%.
41. The amorphous oxide-based compound of claim 38, having a
substantially planar configuration for an electrolyte medium.
42. An electrolyte medium comprising at least one layer of
amorphous lithium carbon lanthanum zirconium oxide.
43. The electrolyte medium of claim 42, wherein said amorphous
lithium carbon lanthanum zirconium oxide comprises by percentage of
total number of atoms from about 0.1% to about 50% lithium, up to
about 25% carbon, from about 0.1% to about 25% lanthanum, from
about 0.1% to about 25% zirconium, and from about 30% to about 70%
oxygen.
44. A method of synthesizing amorphous lithium carbon lanthanum
zirconium oxide comprising: producing a mixture by substantially
dissolving in a solvent, a first precursor solute comprising a
compound of lithium, a second precursor solute comprising a
compound of lanthanum, and a third precursor solute comprising a
compound of zirconium; and dispensing said mixture in a
substantially planar configuration and drying and curing to a
substantially dry phase.
45. The method of claim 44, wherein the step of drying and curing
said mixture comprises exposing and heating said mixture in an
environment comprising air and ozone, wherein a concentration of
said ozone in said air is greater than 0.05 parts per million.
46. The method of claim 45, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; and then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes.
47. The method of claim 45, wherein the steps of exposing and
heating said mixture in an environment comprising air and ozone are
followed by the step of heating said mixture in air.
48. The method of claim 47, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes; and then heating said
mixture in air at about 300.degree. C. for about 30 minutes.
49. The method of claim 44, wherein said solvent comprises an
alcohol-based solvent, said first precursor solute comprises
lithium alkoxide, said second precursor solute comprises lanthanum
alkoxide, and said third precursor solute comprises zirconium
alkoxide.
50. The method of claim 49, wherein said alcohol-based solvent
comprises methoxyethanol.
51. The method of claim 49, wherein said lithium alkoxide comprises
lithium butoxide, said lanthanum alkoxide comprises lanthanum
methoxyethoxide, and said zirconium alkoxide comprises zirconium
butoxide.
52. The method of claim 51, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide.
53. The method of claim 51, wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
54. The method of claim 51, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide; and wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
55. The method of claim 44, wherein said mixture is dispensed into
a substantially planar configuration by one of spin coating,
casting, dip coating, spray coating, screen printing and ink-jet
printing.
56. The method of claim 44, wherein the mixture further comprises a
polymer.
57. The method of claim 56, wherein the step of drying and curing
said mixture comprises exposing and heating said mixture in an
environment comprising air and ozone, wherein a concentration of
said ozone in said air is greater than 0.05 parts per million.
58. The method of claim 57, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; and then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes.
59. The method of claim 57, wherein the steps of exposing and
heating said mixture in an environment comprising air and ozone are
followed by the step of heating said mixture in air.
60. The method of claim 59, wherein the step of drying and curing
said mixture further comprises: exposing said mixture to said
environment comprising air and ozone for about one hour; then
heating said mixture in said environment comprising air and ozone
at about 80.degree. C. for about 30 minutes; and then heating said
mixture in air at about 300.degree. C. for about 30 minutes.
61. The method of claim 56, wherein said solvent comprises an
alcohol-based solvent, said first precursor solute comprises
lithium alkoxide, said second precursor solute comprises lanthanum
alkoxide, and said third precursor solute comprises zirconium
alkoxide.
62. The method of claim 61, wherein said alcohol-based solvent
comprises methoxyethanol and said polymer comprises polyvinyl
pyrrolidone.
63. The method of claim 61, wherein said lithium alkoxide comprises
lithium butoxide, said lanthanum alkoxide comprises lanthanum
methoxyethoxide, and said zirconium alkoxide comprises zirconium
butoxide.
64. The method of claim 63, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide.
65. The method of claim 63, wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide.
66. The method of claim 56, wherein said polymer comprises an
amount of said polymer pre-dissolved in an amount of said
alcohol-based solvent to produce a polymer solution.
67. The method of claim 63, wherein said lanthanum methoxyethoxide
comprises an amount of said lanthanum methoxyethoxide pre-dissolved
in an amount of said alcohol-based solvent to produce a lanthanum
methoxyethoxide solution comprising about 12% by weight of said
lanthanum methoxyethoxide; wherein said zirconium butoxide
comprises an amount of said zirconium butoxide pre-dissolved in an
amount of butanol to produce a zirconium butoxide solution
comprising about 80% by weight of said zirconium butoxide; and
wherein said polymer comprises an amount of said polymer
pre-dissolved in an amount of said alcohol-based solvent to produce
a polymer solution.
68. The method of claim 67, wherein said alcohol-based solvent
comprises methoxyethanol and said polymer comprises polyvinyl
pyrrolidone.
69. The method of claim 56, wherein said mixture is dispensed into
a substantially planar configuration by one of spin coating,
casting, dip coating, spray coating, screen printing, and ink-jet
printing.
70. The method of claim 8, wherein said solvent comprises an
alcohol-based solvent, and wherein at least one of said first
precursor solute, said second precursor solute, and said third
precursor solute comprises a metal .beta.-diketonate.
71. The method of claim 70, wherein the metal .beta.-diketonate
comprises a metal acetyl acetonate.
72. The method of claim 16, wherein said solvent comprises an
alcohol-based solvent, and wherein at least one of said first
precursor solute, said second precursor solute, and said third
precursor solute comprises a metal .beta.-diketonate.
73. The method of claim 72, wherein the metal .beta.-diketonate
comprises a metal acetyl acetonate.
74. The method of claim 44, wherein said solvent comprises an
alcohol-based solvent, and wherein at least one of said first
precursor solute, said second precursor solute, and said third
precursor solute comprises a metal .beta.-diketonate.
75. The method of claim 74, wherein the metal .beta.-diketonate
comprises a metal acetyl acetonate.
76. The method of claim 56, wherein said solvent comprises an
alcohol-based solvent, and wherein at least one of said first
precursor solute, said second precursor solute, and said third
precursor solute comprises a metal .beta.-diketonate.
77. The method of claim 76, wherein the metal .beta.-diketonate
comprises a metal acetyl acetonate.
78. The method of claim 7, wherein the mixture further comprises at
least one gelling, drying, and/or curing control agent.
79. The method of claim 78, wherein the at least one gelling,
drying, and/or curing control agent is selected from the group
consisting of acetylacetone, acetic acid, ethanol, and an
ethanol/water mixture.
80. The method of claim 8, wherein the mixture further comprises at
least one gelling, drying, and/or curing control agent.
81. The method of claim 80, wherein the at least one gelling,
drying, and/or curing control agent is selected from the group
consisting of acetylacetone, acetic acid, ethanol, and an
ethanol/water mixture.
82. The method of claim 44, wherein the mixture further comprises
at least one gelling, drying, and/or curing control agent.
83. The method of claim 82, wherein the at least one gelling,
drying, and/or curing control agent is selected from the group
consisting of acetylacetone, acetic acid, ethanol, and an
ethanol/water mixture.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/848,991, filed Aug. 2, 2010, which is a
continuation-in-part of U.S. patent application Ser. No. 12/163,044
filed Jun. 27, 2008, which claims priority to U.S. Provisional
Application No. 60/947,016, filed Jun. 29, 2007, the entirety of
which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] A battery cell is a useful article that provides stored
electrical energy that can be used to energize a multitude of
devices, particularly portable devices that require an electrical
power source. The cell is an electrochemical apparatus typically
formed of at least one ion-conductive electrolyte medium disposed
between a pair of spaced-apart electrodes commonly known as an
anode and a cathode. Electrons flow through an external circuit
connected between the anode and cathode. The electron flow is
caused by the chemical-reaction-based electric potential difference
between the active anode material and active cathode material. The
flow of electrons through the external circuit is accompanied by
ions being conducted through the electrolyte between the
electrodes.
[0003] Electrode and electrolyte cell components typically are
chosen to provide the most effective and efficient battery for a
particular purpose. Lithium is a desirable active anode material
because of its light weight and characteristic of providing a
favorable reduction potential with several active cathode
materials. Liquid and aqueous electrolytes have often been chosen
because of favorable ion-conducting capabilities. Despite the
benefits provided by certain anode materials and electrolytes, the
materials themselves and, often, the combination of a particular
electrode material and a particular electrolyte can cause problems
in cell performance and, in some instances, can create a hazardous
condition. For example, as advantageous as lithium can be as an
active anode material, it can be degraded and otherwise react
undesirably with such common mediums as air and water, and certain
solvents. As a further example of problems, certain liquids that
are useful as effective electrolytes can create hazardous
conditions when serving as components of a lithium-ion battery.
[0004] For the reasons broadly stated above, it is often desirable
to use a non-aqueous and non-liquid electrolyte medium in cells.
Non-aqueous electrolyte mediums are desired because water can
interact undesirably with some desirable electrode materials such
as lithium. Non-liquid electrolyte mediums are desired for several
reasons. One reason is that liquid electrolytes often react
detrimentally with desirable electrode substances such as lithium
even though the liquid is non-aqueous. Another reason that liquid
electrolytes can be undesirable is the need to prevent electrolytic
material from freely flowing beyond a predetermined geometric
boundary configuration. For example, leakage of electrolyte
solution from the battery container is typically undesirable.
Another problem with liquid electrolytes is that some solvents that
are used as effective non-aqueous, liquid electrolytes are
flammable and have a relatively high vapor pressure. The
combination of flammability and high-vapor pressure creates a
likelihood of combustion. Further in this regard, batteries that
use lithium-based anodes can pose severe safety issues due to the
combination of a highly volatile, combustible electrolyte and the
active nature of lithium metal.
[0005] Some of the problems associated with particular cell
electrodes and electrolyte can result in internal failure of the
cell. One type of internal failure is the discharge of electric
current internally, within the cell, rather than externally of the
cell. Internal discharge may also be referred to as
"self-discharge." Self-discharge can result in high current
generation, overheating and ultimately, a fire. A primary cause of
self-discharge has been dendritic lithium growth during recharge of
a rechargeable battery. In rechargeable cells having lithium
anodes, dendrites are protuberances extending from the anode base
that are formed during imperfect re-plating of the anode during
recharge. Dendrites or growths resulting from low-density lithium
plating during recharge can grow through the separator that
separates anode from cathode particularly if the separator is
porous or solid but easily punctured by the growth. When the
growths extend far enough to interconnect the anode and cathode, an
internal electrical short circuit is created through which current
can flow. Electrical current produces heat that will vaporize a
volatile electrolyte substance. In turn, vaporization of the
electrolyte can produce extreme pressure within the battery housing
or casing which can ultimately lead to rupture of the housing or
casing. The temperatures that result from an electrical short
circuit within a battery are sometimes high enough to ignite
escaping electrolyte vapors thereby causing continuing degradation
and the release of violent levels of energy. Lithium-ion batteries
were developed to eliminate dendritic lithium growth by utilizing
the lithium ions inserted into graphite anodes rather than
re-platable lithium metal anodes. Although these lithium-ion
batteries are much safer than earlier designs, violent failures
still occur.
[0006] Ion-conductive, solid-glass electrolytes and ceramic
electrolytes have been developed in the past to address the need
for an electrolyte medium without the shortcomings described above.
These solutions have included glass electrolyte materials such as
Lithium Phosphorous Oxy-Nitride (LiPON) and a class of
glass-ceramic materials generally referred to as LiSICON (an
acronym for Lithium Super-Ionic Conductor) structure-type materials
and NaSICON (an acronym for Sodium Super-Ionic Conductor, wherein
the "Na" portion of the acronym is the chemical symbol for sodium)
structure-type materials. However, these materials have
limitations. LiPON has low ionic conductivity, in the range of
1.2E-6 S/cm, and generally can only be applied or used as thin
films less than 10 .mu.m thick. In addition, it has to be produced
using a reactive sputtering process in a low vacuum environment
which can be very expensive. LiPON is also unstable in contact with
water which eliminates its possible use as a protective electrolyte
in battery systems where exposure to moisture or ambient air may
occur. On the other hand LiSICON and NaSICON structure-type
materials are stable in contact with water but are unstable in
contact with lithium. When in contact with lithium this class of
materials turns dark and can conduct electric current by electron
flow thus minimizing usefulness as electrolyte separators.
[0007] Thus it can be appreciated that it would be useful to have a
cell electrolyte medium that is a conductor of ions, that is
protective of and stable in contact with lithium, that is
non-aqueous, that is non-liquid, that is non-flammable, and that
does not produce short circuits that are associated with dendritic
plating of lithium.
BRIEF SUMMARY OF THE INVENTION
[0008] According to a first embodiment the invention provides an
amorphous oxide-based compound having a general formula
M.sub.wM'.sub.xM''.sub.yM'''.sub.zC.sub.a,
[0009] wherein M is at least one alkali metal;
[0010] M' is at least one metal selected from the group consisting
of lanthanides, barium, strontium, calcium, indium, magnesium,
yttrium, scandium, chromium, aluminum, and alkali metals, provided
that when M' is an alkali metal, M' further contains at least one
non-alkali M' metal;
[0011] M'' is at least one metal selected from the group consisting
of zirconium, tantalum, niobium, antimony, tin, hafnium, bismuth,
tungsten, silicon, selenium, gallium and germanium;
[0012] M''' comprises oxygen and optionally at least one element
selected from the group consisting of sulfur and halogens; and
[0013] w, x, y, and z are positive numbers, including various
combinations of integers and fractions or decimals, and "a" may be
zero or a positive number.
[0014] In accordance with an aspect of the first embodiment, M
comprises lithium, M' comprises lanthanum, M'' comprises zirconium,
and M''' comprises oxygen.
[0015] In accordance with another aspect of the first embodiment,
by percentage of total number of atoms, M comprises from about 0.1%
to about 50%, M' comprises from about 0.1% to about 25%, M''
comprises from about 0.1% to about 25%, M''' comprises from about
30% to about 70%, and carbon comprises from 0.0% to about 25%.
[0016] According to a second embodiment of the present invention,
an electrolyte medium for an electrochemical cell comprises a layer
of amorphous lithium lanthanum zirconium oxide.
[0017] In accordance with an aspect of the second embodiment, the
layer of amorphous lithium lanthanum zirconium oxide comprises by
percentage of total number of atoms from about 0.1% to about 50%
lithium, from about 0.1% to about 25% lanthanum, from about 0.1% to
about 25% zirconium, from about 30% to about 70% oxygen and from
0.0% to about 25% carbon.
[0018] According to a third embodiment of the present invention, a
method for synthesizing an amorphous oxide-based compound
comprises
[0019] substantially dissolving in a quantity of an alcohol-based
solvent to produce a mixture, quantities of an alkoxide of at least
one alkali-metal, an alkoxide of at least one metal selected from
the group consisting of lanthanides, barium, strontium, calcium,
indium, magnesium, yttrium, scandium, chromium, aluminum, and
alkali metals, provided that when the metal is an alkali metal, it
further contains at least one metal selected from lanthanides,
barium, strontium, calcium, indium, magnesium, yttrium, scandium,
chromium, and aluminum; an alkoxide of at least one metal selected
from the group consisting of zirconium, tantalum, niobium,
antimony, tin, hafnium, bismuth, tungsten, silicon, selenium,
gallium and germanium; and optionally an alcohol-soluble precursor
of at least one of sulfur, selenium, and a halogen,
[0020] dispensing said mixture in a substantially planar
configuration, transitioning through a gel phase, and drying and
curing to a substantially dry phase.
[0021] According to a fourth embodiment of the invention, amorphous
lithium lanthanum zirconium oxide is synthesized by substantially
dissolving quantities of a lanthanum alkoxide, a lithium alkoxide,
and a zirconium alkoxide in a quantity of an alcohol-based solvent
to produce a mixture; then dispensing the mixture into a
substantially planar configuration, transitioning through a gel
phase, and drying and curing to a substantially dry phase.
[0022] In accordance with an aspect of the fourth embodiment, the
alcohol-based solvent comprises methoxyethanol.
[0023] In accordance with another aspect of the fourth embodiment,
the lanthanum alkoxide comprises lanthanum methoxyethoxide, the
lithium alkoxide comprises lithium butoxide and the zirconium
alkoxide comprises zirconium butoxide.
[0024] In accordance with yet another aspect of the fourth
embodiment, the quantity of lanthanum methoxyethoxide comprises an
amount of lanthanum methoxyethoxide pre-dissolved in an amount of
the alcohol-based solvent to produce a lanthanum methoxyethoxide
solution comprising about 12% by weight lanthanum
methoxyethoxide.
[0025] In accordance with an additional aspect of the fourth
embodiment, the quantity of zirconium butoxide comprises an amount
of zirconium butoxide pre-dissolved in an amount of butanol to
produce a zirconium butoxide solution comprising about 80% by
weight said zirconium butoxide.
[0026] In accordance with yet an additional aspect of the fourth
embodiment, the quantity of lanthanum methoxyethoxide comprises
about 4.5 grams of the lanthanum methoxyethoxide solution, the
quantity of lithium butoxide comprises about 0.65 grams thereof,
the quantity of zirconium butoxide comprises about 0.77 grams of
the zirconium butoxide solution and the alcohol-based solvent
comprises about 5 grams of methoxyethanol.
[0027] In accordance with a further aspect of the fourth
embodiment, the mixture is dispensed into a substantially planar
configuration by one of spin coating, casting, dip coating, spray
coating, screen printing or ink-jet printing.
[0028] According to a fifth embodiment of the invention, amorphous
lithium lanthanum zirconium oxide is synthesized by substantially
dissolving quantities of a lanthanum alkoxide, a lithium alkoxide,
a zirconium alkoxide and a polymer in a quantity of an
alcohol-based solvent to produce a mixture; then dispensing the
mixture into a substantially planar configuration, transitioning
through a gel phase, and drying and curing to a substantially dry
phase.
[0029] In accordance with an aspect of the fifth embodiment, the
alcohol-based solvent comprises methoxyethanol and the polymer
comprises polyvinyl pyrrolidone.
[0030] In accordance with another aspect of the fifth embodiment,
the lithium alkoxide comprises lithium butoxide, the lanthanum
alkoxide comprises lanthanum methoxyethoxide, and the zirconium
alkoxide comprises zirconium butoxide.
[0031] In accordance with yet another aspect of the fifth
embodiment, the quantity of lanthanum methoxyethoxide comprises an
amount of lanthanum methoxyethoxide pre-dissolved in an amount of
the alcohol-based solvent to produce a lanthanum methoxyethoxide
solution comprising about 12% by weight lanthanum
methoxyethoxide.
[0032] In accordance with an additional aspect of the fifth
embodiment, the quantity of zirconium butoxide comprises an amount
of zirconium butoxide pre-dissolved in an amount of butanol to
produce a zirconium butoxide solution comprising about 80% by
weight said zirconium butoxide.
[0033] In accordance with yet another additional aspect of the
fifth embodiment, the quantity of polymer comprises an amount of
polymer pre-dissolved in an amount of alcohol-based solvent to
produce a polymer solution
[0034] In accordance with a further aspect of the fifth embodiment,
the quantity of lanthanum methoxyethoxide comprises about 4.5 grams
of lanthanum methoxyethoxide solution, the quantity of lithium
butoxide comprises about 0.65 grams thereof, the quantity of
zirconium butoxide comprises about 0.77 grams of said zirconium
butoxide solution, the quantity of polymer solution comprises not
more than about 2 grams of polyvinyl pyrrolidone dissolved in about
5 grams of methoxyethanol, and the quantity of alcohol-based
solvent comprises about 5 grams of methoxyethanol.
[0035] In accordance with yet a further aspect of the fifth
embodiment, the mixture is dispensed into a substantially planar
configuration by one of spin coating, casting, dip coating, spray
coating, screen printing or ink-jet printing.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0036] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
embodiments which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown.
[0037] In the drawings:
[0038] FIG. 1 is schematic representation of a cell suitable for
incorporating an electrolyte medium in accordance with the present
invention;
[0039] FIG. 2 depicts XPS Spectra Graphs for amorphous LLZO films
according to an embodiment of the invention;
[0040] FIG. 3 depicts EIS spectra of amorphous LLZO films according
to an embodiment of the invention;
[0041] FIG. 4 is a Nyquist plot of the full EIS spectrum of an
amorphous LLZO film with partial substitution by aluminum according
to an embodiment of the invention;
[0042] FIG. 5 is a Nyquist plot of an amorphous LLZO film with
partial substitution by aluminum according to an embodiment of the
invention focusing on high frequency real axis intercept;
[0043] FIG. 6 is a Nyquist plot of the full EIS spectra of an
amorphous LLZO film with addition of acetylacetonate according to
an embodiment of the invention; and
[0044] FIG. 7 is a Nyquist plot of an amorphous LLZO film with
addition of acetylacetonate according to an embodiment of the
invention focusing on high frequency real axis intercept.
DETAILED DESCRIPTION OF THE INVENTION
[0045] This invention relates to ionically-conductive materials
useful as electrolyte mediums in electrochemical cells, and more
particularly, the invention relates to an ionically-conductive
amorphous lithium lanthanum zirconium oxide composition formable as
an electrolyte medium for an electrochemical cell such as a battery
cell.
[0046] Embodiments of the present invention are described herein.
The disclosed embodiments are merely exemplary of the invention
that may be embodied in various and alternative forms, and
combinations thereof. As used herein, the word "exemplary" is used
expansively to refer to embodiments that serve as illustrations,
specimens, models, or patterns. The figures are not necessarily to
scale and some features may be exaggerated or minimized to show
details of particular components. In other instances, well-known
components, systems, materials, or methods have not been described
in detail in order to avoid obscuring the present invention.
Therefore, at least some specific structural and functional details
disclosed herein are not to be interpreted as limiting, but merely
as a basis for the claims and as a representative basis for
teaching one skilled in the art to variously employ the present
invention.
[0047] Referring to FIG. 1, therein is illustrated a
cross-sectional, schematic representation of a battery cell, or
electrochemical cell, 10 suitable for incorporating an electrolyte
medium in accordance with the present invention. A
centrally-disposed cathode current collector 11 is flanked on
either side by a cathode 12. An electrolyte medium 13 is disposed
in a U-shaped, face-contacting relationship with the cathodes 12.
An anode 14 is disposed in a U-shaped, face-contacting relationship
with the electrolyte medium 13. An anode current collector 15 is
disposed in a U-shaped, face-contacting relationship with the anode
14. A cathode terminal 16 is disposed in contacting relationship
with the cathode current collector 11 and cathode 12.
Overview
[0048] Lithium is a desirable substance to use as an electrode
(particularly an anode) in a cell. This is because lithium is one
of the lightest of elements, while possessing high energy density
and high specific energy. However, lithium is extremely undesirably
reactive with water and is likewise undesirably reactive with many
highly ionically-conductive liquid electrolytes. Thus, it is
desirable to have an electrolyte medium that is non-aqueous and
non-liquid so as to be compatible with electrodes containing or
consisting of lithium. A solid electrolyte is non-aqueous and
non-liquid; however, some solid electrolytes still react
undesirably with lithium. Thus, it is desirable to have an
electrolyte medium that not only is non-aqueous and non-liquid but
that is also otherwise compatible with electrodes that contain or
comprise lithium.
[0049] Often, batteries are used in applications that require
unique geometries and physical specifications for the battery
package. For example, batteries are used in very small electronic
devices that require batteries to be sized on the order of
millimeters or less. For applications requiring batteries of very
small dimensions, it is important that the components of these
battery cells perform effectively even though produced at a very
small size. Thus, it is important to have an electrolyte medium
that is effective even though produced on an extremely small
scale.
[0050] One method of producing cells of very small dimensions is to
construct what are known as "thin-film" batteries. Typically, in
thin-film battery cells the electrodes and electrolyte medium
comprise substrates having a thin, film-like configuration.
Thin-film batteries also have the advantage of potentially being
flexible. The electrolyte medium for thin-film battery cells has to
be effective even though produced at very small dimensions.
The Invention in Detail
[0051] The invention is an effective, ionically-conductive
composition for an electrolyte medium. The invention further
encompasses a method for producing the composition in general and a
method for forming an electrolyte medium comprising the
composition. The electrolyte medium taught by the invention is
non-aqueous, non-liquid, inorganic, and compatible with lithium and
lithium-containing compositions, and can be manufactured in
thin-dimensioned and small-dimensioned configurations.
[0052] In an embodiment, the composition of the invention is
amorphous lithium lanthanum zirconium oxide (for convenience,
sometimes this composition is referred to herein as "LLZO"). As
explained in more detail below, amorphous LLZO prepared by the
method of the invention often contains carbon and thus is more
properly named lithium carbon lanthanum zirconium oxide (LCLZO).
For the purposes of this disclosure, the term "LLZO" may be
understood to refer to LLZO and/or LCLZO. The amorphous LLZO is
highly ionically-conductive. It is inorganic and compatible with
lithium. It can be used to produce a solid, thin-film electrolyte
medium that facilitates incorporation into a small-dimensioned
energy cell.
[0053] The amorphous LLZO is unique as an electrolyte medium as
well as in and of itself The invention teaches that the amorphous
compound may have a chemical make-up wherein certain other elements
may be partially or fully substituted for the four primary
constituent elements lithium, lanthanum, zirconium and oxygen.
Substitutes for the lithium constituent include elements in the
alkali-metal family of the Periodic Table. Substitutes for the
lanthanum constituent include barium, strontium, calcium, indium,
magnesium, yttrium, scandium, chromium, aluminum, elements in the
alkali-metal family of the Periodic Table and elements in the
lanthanide series of the Periodic Table. Substitutes for the
zirconium constituent include tantalum, niobium, antimony, tin,
hafnium, bismuth, tungsten, silicon, selenium, gallium and
germanium. Substitutes for the oxygen constituent include sulfur,
selenium, and elements in the halogen family of the Periodic
Table.
[0054] In an embodiment, an amorphous compound has a general
formula M.sub.wM'.sub.xM''.sub.yM'''.sub.zC.sub.a wherein M is at
least one alkali metal;
[0055] M' is at least one metal selected from the group consisting
of lanthanides, barium, strontium, calcium, indium, magnesium,
yttrium, scandium, chromium, aluminum, and alkali metals, provided
that when M' is an alkali metal, M' further contains at least one
non-alkali M' metal;
[0056] M'' is at least one metal selected from the group consisting
of zirconium, tantalum, niobium, antimony, tin, hafnium, bismuth,
tungsten, silicon, selenium, gallium and germanium;
[0057] M''' comprises oxygen and optionally at least one element
selected from the group consisting of sulfur and halogens; and
w, x, y, and z are positive numbers, including various combinations
of integers and fractions or decimals, and "a" may be zero or a
positive number. When "a" is zero, the compound has general formula
M.sub.wM'.sub.xM''.sub.yM'''.sub.z.
[0058] The amorphous compound of the invention can be produced by a
relatively simple and inexpensive process. One broad category of
process is a sol-gel class of process. In an embodiment, the
invention teaches adaptation of a sol-gel technique, which is
generally known in chemistry, to form the ultimate, substantially
solid compound and medium of the invention. In the invention's
application of a sol-gel process a precursor solution mixture is
derived from substantial dissolution of liquid or/and solid solutes
in a solvent. The sol-gel technique is advantageous because it is
not necessary to subject the amorphous-LLZO precursor ingredients
to extreme high temperatures as is necessary in the case of
solid-state reactions and other processes for producing
solid-electrolyte mediums. Extreme high temperatures are unwanted
because such temperatures can produce undesirable effects in
electrolyte membranes that are formed and/or in associated
components.
[0059] In an embodiment, the amorphous compound of the invention is
created through a sol-gel methodology by processing alkoxides that
contain desired end constituent elements. In an embodiment of
methodology of the invention, alkoxides of each of four primary
constituents described above are dissolved in a quantity of an
alcohol-based solvent to produce a mixture; the mixture is
dispensed in a substantially planar configuration, transitioned
through a gel phase, and dried and cured to a substantially dry
phase.
[0060] In an embodiment, alkoxides of other elements may be
substituted for the four primary constituent element alkoxides.
Thus, in an embodiment, an amorphous compound is synthesized by
substantially dissolving quantities of
[0061] an alkoxide of at least one alkali-metal,
[0062] an alkoxide of at least one metal selected from the group
consisting of barium, strontium, calcium, indium, magnesium,
yttrium, scandium, chromium, aluminum, alkali-metals, and the
lanthanides,
[0063] an alkoxide of at least one metal selected from the group
consisting of zirconium, tantalum, niobium, antimony, tin, hafnium,
bismuth, tungsten, silicon, selenium, gallium and germanium,
and
[0064] optionally an alcohol-soluble precursor of at least one of
sulfur, selenium, and a halogen, in a quantity of an alcohol-based
solvent to produce a mixture; dispensing the mixture in a
substantially planar configuration, transitioning through a gel
phase, and drying and curing to a substantially dry phase.
[0065] While the process has been described with respect to metal
alkoxides as precursors, the method of the invention is not limited
to such metal compounds. Rather, it is also within the scope of the
invention to utilize other alcohol soluble precursor compounds
which promote the formation of the desired metal oxide in a sol-gel
process, such as, but not limited to, metal .beta.-diketonates. For
example, metal acetylacetonate (metal acac) may be used as the
metal source in the precursor solution.
[0066] It is also within the scope of the invention to include
additional components in the precursor solution, such as acetic
acid, ethanol, an ethanol/water mixture, and acetylacetone (acac).
These components influence the gelling, drying, and/or curing steps
during the sol gel synthesis, thus affecting the properties of the
final material, such as density and morphology. It has been found
that such gelling, drying, and/or curing control agents may help to
obtain a film, rather than a colloidal structure, of the final
material. Appropriate amounts of these additives may be determined
by routine experimentation.
[0067] In an embodiment of the invention, in a method for
synthesizing amorphous LLZO, quantities of a lanthanum alkoxide, a
lithium alkoxide, and a zirconium alkoxide are dissolved in a
quantity of an alcohol-based solvent to produce a mixture. A
suitable lanthanum alkoxide is lanthanum methoxyethoxide, a
suitable lithium alkoxide is lithium butoxide, a suitable zirconium
alkoxide is zirconium butoxide, and a suitable alcohol-based
solvent is methoxyethanol. The solutes and solvent are mixed in
quantities and percentages to bring about substantially complete
dissolution. The mixture (the precursor solution formed by mixing)
is dispensed into a substantially planar configuration, processed
through a "gel" phase, dried and cured to a substantially dry
phase.
SYNTHESIS EXAMPLES
[0068] The ingredients in the examples described below are
readily-obtainable chemical compositions that may be purchased from
many different chemical suppliers in the United States such as
Gelest, Inc. (Morrisville, Pa.) and Alfa Aesar (Ward Hill,
Mass.).
[0069] Lithium butoxide is also know as lithium tert-butoxide
(LTB); lithium t-butoxide; lithium tert-butoxide; lithium
tert-butylate; 2-methyl-2-propanolithium salt; 2-methyl-2-propanol
lithium salt; lithium tert-butanolate; tert-butoxylithium;
tert-butylalcohol, lithium salt; lithium tert-butoxide solution;
lithium butoxide min off white powder; and lithium
2-methylpropan-2-olate. It has the molecular formula
C.sub.4H.sub.9LiO. It in particular may be purchased from Gelest,
Inc.
[0070] Lanthanum methoxyethoxide is also known as lanthanum (III)
2-methoxyethoxide, lanthanum 2-methoxyethoxide; lanthanum
methoxyethoxide; lanthanum methoxyethylate; and lanthanum
tri(methoxyethoxide). It has the molecular formula
C.sub.9H.sub.21LaO.sub.6. It in particular may be purchased from
Gelest, Inc.
[0071] Zirconium butoxide is also known as 1-butanol, zirconium(4+)
salt; butan-1-olate, zirconium(4+); butyl alcohol, zirconium(4+)
salt; butyl zirconate; butyl zirconate(IV); tetrabutoxyzirconium;
tetrabutyl zirconate; zirconic acid butyl ester; zirconium
tetrabutanolate; and zirconium tetrabutoxide. It has the molecular
formula C.sub.16H.sub.36O.sub.4Zr. It in particular may be
purchased from Gelest, Inc.
[0072] Methoxyethanol is also known as 2-methoxyethanol (2ME);
ethylene glycol monomethyl ether (EGME) and methyl cellosolve. It
has the molecular formula C.sub.3H.sub.8O.sub.2. It in particular
may be purchased from Alfa Aesar.
[0073] After thorough mixing of the ingredients and substantially
complete dissolution of the solutes, the resulting mixture is
processed through a fluidized stage that includes, at least
briefly, aspects of a gel state. The fully-mixed, applied and
processed components produce an amorphous substrate of LLZO.
[0074] In the amorphous LLZO compound of the invention, the number
of atoms of lithium, lanthanum, zirconium, and oxygen are
proportional to one another within ranges as set forth in the table
of Atomic Percentage(s) below. For convenience, the amorphous
compound is referred to herein simply as LLZO although the compound
may also contain carbon as a result of the synthesis process.
Further, for convenience, the compound may be denoted by the
general formula Li.sub.wLa.sub.xZr.sub.yO.sub.z wherein w, x, y,
and z are positive numbers, including various combinations of
integers and fractions or decimals representative of the
proportional relationship of the elements to one another.
Carbon as Additional Element
[0075] The production techniques described herein for producing
amorphous LLZO may produce a product that contains some quantity of
carbon. The carbon is left over as a by-product from one or more of
the organic compositions used as precursors in formulating the
amorphous LLZO. The atomic percentage of carbon in the amorphous
composition is in the range from 0.0% to about 25%. Thus, as
previously explained, LLZO may often be more correctly referred to
as LCLZO.
[0076] The percentages of the number of atoms of each element as a
proportion of the total number of atoms in the amorphous
composition is as shown in the following table:
TABLE-US-00001 Chemical Element in Amorphous Atomic Percentage of
Each Composition Element in the Composition Lithium from about 0.1%
to about 50% Lanthanum from about 0.1% to about 25% Zirconium from
about 0.1% to about 25% Oxygen from about 30% to about 70% Carbon
from 0.0% to about 25%
Example 1
Production of Amorphous LLZO Electrolyte Medium
[0077] An amorphous LLZO precursor solution was prepared by
dissolving about 4.5 grams of a lanthanum methoxyethoxide solution,
about 0.65 gram of lithium butoxide and about 0.77 gram of a
zirconium butoxide solution in about 5 grams of methoxyethanol.
[0078] Lanthanum methoxyethoxide and zirconium butoxide were used
in solution form for convenience in mixing. However, the invention
encompasses the use of these compositions without being
pre-dissolved. The lanthanum methoxyethoxide solution comprised
lanthanum methoxyethoxide pre-dissolved in methoxyethanol whereby
lanthanum methoxyethoxide comprised approximately 12% by weight of
the total weight of the lanthanum methoxyethoxide solution.
Similarly, the zirconium butoxide solution comprised zirconium
butoxide pre-dissolved in butanol whereby zirconium butoxide
comprised approximately 80% by weight of the zirconium butoxide
solution.
[0079] The components may be mixed in any sequence, as the sequence
of mixing is not significant. The thoroughly-mixed precursor
solution was left in a bottle in a dry environment for about 1 to
1.5 hours to help facilitate substantially complete dissolution of
the lithium butoxide, the component that was not pre-dissolved.
What is meant by "dry environment" is that moisture in the ambient
air is low enough that lithium components are not degraded due to
moisture.
Example 1(A)
Formation of Film by Spin Coating
[0080] The precursor solution prepared in Example 1 was deposited
by known spin-coating processes at approximately 1200 rpm for about
15 seconds in a dry environment. The resulting layer of composition
was placed in a closed container and exposed to an ozone-rich air
environment (ozone concentration larger than 0.05 part per million
(ppm)) for approximately 1 hour.
[0081] The term "environment" refers to the enclosed space in which
a process (or sub-process) is carried out in the methodology taught
by the invention. A vaporous or gaseous element or composition in
the enclosure facilitates the drying, curing or other desired
chemical processing. A gas or vapor may be placed in a suitable
enclosure by known chemical processing means. For example, a vapor
or gas may be injected through a port. As a further example, a
liquid may be placed in the enclosure and permitted (or caused) to
vaporize, thereby creating the desired vaporous or gaseous
environment. In this step, as an alternative, the closed
environment may be solvent-vapor-rich (for example wherein a
quantity of a solvent such as methoxyethanol is disposed in the
closed container in a liquid phase and permitted or caused to
vaporize). As another alternative, the closed environment may
contain a gaseous mixture of ozone-rich air and solvent-vapor-rich
air.
[0082] This was followed by heating at approximately 80.degree. C.
for about 30 minutes, also in an ozone-rich air environment. The
LLZO coating and substrate were then heated at approximately
300.degree. C. for 30 minutes in air. It is to be understood that
the heating times and environmental factors such as humidity,
temperature, and gaseous content of ambient air may be varied.
[0083] The described spin-coating process resulted in an amorphous
LLZO layer whose thickness was approximately 250 nm. Thicker films
or layers of amorphous LLZO may be formed by repeating the basic
spin-coating processing steps multiple times until the desired
thickness is achieved.
Example 1(B)
Formation of Film by Casting
[0084] A LLZO precursor solution described in Example 1 was
optionally heated at approximately 100.degree. C. under an inert
gas to increase the density and viscosity of the solution. This
optional step was utilized in some samples that were produced.
[0085] The amorphous LLZO precursor solution was cast on a suitable
substrate that facilitated support and then selective release of
the formed layer. The layer that was formed was initially a
solution. After further processing the layer may transition into a
film, or a powder, or a combination of two or more of solution,
film and powder. The freshly-cast LLZO was placed in a closed
container and exposed to ozone-rich air environment (ozone
concentration larger than 0.05 ppm) for approximately 1 hour,
although longer exposure times may be used as well. In this step,
as an alternative, the closed environment may be solvent-vapor-rich
(for example wherein a quantity of a solvent such as methoxyethanol
is disposed in the closed container in a liquid phase and allowed
to and/or caused to vaporize). As another alternative, the closed
environment may contain a mixture of ozone-rich air and
solvent-vapor-rich air. This was followed by heating at
approximately 80.degree. C. for 30 minutes or longer, also in an
ozone-rich air environment. The LLZO material was then heated at
approximately 300.degree. C. for 30 minutes in air. It should be
understood that the heating times and environmental factors such as
humidity, temperature, and gaseous content of ambient air may be
varied. The immediately-above described processing step for the
layer of cast material may result in a thick layer of amorphous
LLZO or amorphous LLZO powder, or, to some degree, a thin film.
Example 2
of Production of Amorphous LLZO Electrolyte Medium--Incorporation
of PVP into Precursor
[0086] The LLZO precursor solution was prepared in the following
fashion. First, a quantity of a polymer, polyvinyl pyrrolidone
(PVP), generally not exceeding 2 grams, was added to about 5 grams
of methoxyethanol (2ME) and the mixture was allowed to sit for
approximately 1 hour so that the PVP could be fully dissolved and
form a substantially homogeneous PVP/2ME solution. Then about 4.5
grams of lanthanum methoxyethoxide solution, about 0.65 gram of
lithium butoxide and about 0.77gram of zirconium butoxide solution
were dissolved in about 5 grams of methoxyethanol and approximately
1 gram of the PVP/2ME solution.
[0087] Predissolution of PVP in 2ME is not required but may be
carried out in this manner for convenience in mixing. For example,
a suitable amount of PVP may be added to 2ME at the same time that
the other solution components such as lanthanum methoxyethoxide and
zirconium butoxide are mixed together in the solvent. The order of
mixing has no bearing on the final composition and function of the
solution.
[0088] As in Example 1, lanthanum methoxyethoxide and zirconium
butoxide were provided in solution form for convenience in mixing.
The invention also encompasses use of these compositions without
being pre-dissolved. The lanthanum methoxyethoxide solution
comprised lanthanum methoxyethoxide pre-dissolved in methoxyethanol
whereby lanthanum methoxyethoxide comprised approximately 12% by
weight of the total weight of the lanthanum methoxyethoxide
solution. Similarly, the zirconium butoxide solution comprised
zirconium butoxide pre-dissolved in butanol whereby zirconium
butoxide comprised approximately 80% by weight of the zirconium
butoxide solution.
[0089] The components may be mixed in any sequence as the sequence
of mixing is not significant. The thoroughly-mixed precursor
solution was left in a bottle in a dry environment for about 1 to
1.5 hours to help facilitate substantially complete dissolution of
the lithium butoxide, the component that was not pre-dissolved.
[0090] The LLZO precursor solution containing some PVP may be
dispensed into a substrate configuration by either spin coating or
casting as described in Example 1 above. Spin coating was done at
approximately 1200 rpm for about 15 seconds. Both spin coating and
casting are done in a dry environment. The freshly-coated LLZO was
placed in a closed container and exposed to ozone-rich air
environment (ozone concentration larger than 0.05 ppm) for
approximately 1 hour. In this step, as an alternative, the closed
environment may be solvent-vapor-rich (for example wherein a
quantity of a solvent such as methoxyethanol, in liquid phase, is
disposed in the closed container and permitted or caused to
vaporize). As another alternative, the closed environment may
contain a mixture of ozone-rich air and a solvent-vapor-rich air.
This was followed by heating at approximately 80.degree. C. for 30
minutes, also in an ozone-rich air environment. The LLZO coating
and substrate were then heated at approximately 300.degree. C. for
30 minutes in air. It should be understood that the heating times
and environmental factors such as humidity, temperature, and
gaseous content of ambient air may be varied. The immediately
preceding processing step results in a layer or powder of amorphous
LLZO that also contains a small PVP component.
Alternative Embodiments
[0091] The invention may be practiced by synthesizing an amorphous
compound in which a different element is substituted for one or
more of the constituent elements of the amorphous LLZO compound.
Thus, the invention may also be practiced by fully or partially
substituting for lithium, one or more chemical elements from the
alkali metal family (or group) of the Periodic Table such as, but
not limited to, potassium and sodium. The invention also may be
practiced by fully or partially substituting for lanthanum one or
more chemical elements from the group consisting of barium,
strontium, calcium, indium, magnesium, yttrium, scandium, chromium,
aluminum, elements in the alkali metal family (or group) of the
Periodic Table such as, but not limited to potassium, and other
elements in the lanthanoid (also know as lanthanide) series of the
Periodic Table, such as but not limited to, for example, cerium and
neodymium. The invention also may be practiced by fully or
partially substituting for zirconium one or more chemical elements
from the group consisting of tantalum, niobium, antimony, tin,
hafnium, bismuth, tungsten, silicon, selenium, gallium and
germanium. And, lastly, the invention further may be practiced by
fully or partially substituting for oxygen, one or more elements
from the group consisting of sulfur, selenium, and the halogen
family (or group) of the Periodic Table.
Alternative Processing
[0092] All or some of the processing steps during spin coating and
in subsequent processing may be carried out in either pure ozone
(O.sub.3) or an ozone-enriched air environment that is provided.
Or, as a further alternative the environment may be
solvent-vapor-rich (for example wherein a quantity of a solvent
such as methoxyethanol is disposed in the closed container). As
another alternative, the environment may contain a mixture of
ozone-rich air and solvent-vapor-rich air.
[0093] Two sol-gel-type related preparation processes have been
described above, namely, one directed to spin-coating for making
thin films, and the other directed to casting for making thick
layers or powder. The invention also may be practiced by employing
other sol-gel and non-sol-gel related processes for depositing at
least one layer of composition that ultimately results in the
production of at least one layer of amorphous lithium lanthanum
zirconium oxide. Such additional depositing processes include but
are not limited to dip coating, spray coating, screen printing or
ink-jet printing as well as various forms of sputtering, chemical
vapor deposition (CVD) and other fabrication and deposition
techniques.
Representative Test Results and Analytical Data for Amorphous LLZO
Produced
[0094] The table below shows depth profile of composition for a
typical amorphous LLZO thin film produced under the invention. The
data presented are in the form of atomic percentages of the
constituent atoms. The depth profile was achieved by sputtering
away the exposed LLZO film surface at an approximate rate of 0.3
nm/s. The table was constructed from the X-ray photoemission
spectroscopy (XPS) results that are presented in FIG. 2. In the
table, "3d" and "1s" are energy level subshell designations.
Depth Profile of Composition of an Amorphous LLZO Film
TABLE-US-00002 [0095] Sputter Atomic Concentration % time (s) La 3d
O 1s C 1s Zr 3d Li 1s 0 2.5 37.2 32.0 3.7 24.6 200 10.3 49.6 8.3
10.0 21.8 400 10.6 53.3 10.0 10.0 16.1 600 8.9 50.5 8.9 8.5 23.2
800 9.2 51.9 9.4 8.9 20.6 1000 8.1 45.8 7.8 7.5 30.8 1200 8.1 47.4
8.3 7.8 28.4 1400 8.8 46.7 7.1 7.8 29.6 1600 8.6 47.0 8.5 8.0 27.9
1800 9.7 49.2 8.0 8.8 24.5 2000 9.8 48.7 8.2 8.9 24.3
[0096] Referring now to FIG. 2, therein are shown XPS spectra
graphs for atomic species constituting an amorphous LLZO film. The
set of spectra for each atom corresponds to the set of depth
profiling produced by sputtering times discussed and shown in the
table above. In the graphs of FIG. 2, each horizontal axis (x-axis)
displays "Binding Energy" measured in electron volts (eV) and each
vertical axis (y-axis) displays "intensity" measured in "counts per
second" (cps).
[0097] Referring now to FIG. 3, the ionic conductivity of amorphous
LLZO product as taught by the invention was observed. Ionic
conductivity of an amorphous LLZO thin film was measured by
electrochemical impedance spectroscopy (EIS) taking high frequency
real-axis intercept as the lithium ionic resistance of the sample
from which the ionic conductivity was estimated taking the sample
geometry into account. FIG. 3 shows measured EIS spectra of an
amorphous LLZO thin film, full spectra on the left and the real
axis intercept in detail on the right. The spectra are presented in
the form of Nyquist plots. Each horizontal axis (x-axis) displays
impedance (Z') in ohms and each vertical axis (y-axis) displays
impedance (Z'') in ohms. The impedance that is measured by the EIS
method is a complex number having both a real and an imaginary
component. The real portion is displayed as impedance Z' on the
horizontal axis and the imaginary portion is displayed as impedance
Z'' on the vertical axis.
[0098] The EIS results indicate pure ionic conductivity of the
sample, i.e., no evidence of electronic conductivity is observed.
The ionic conductivity, estimated from the sample's film thickness
of approximately 1.25 .mu.m and area of 1 mm.sup.2, is in the range
1 to 2 E-3 S/cm. This conductivity is very high for
room-temperature ionic conductivity of an inorganic
electrolyte.
Example 3
Preparation and Analysis of Amorphous LLZO by Sol Gel with Partial
Substitution by Aluminum
[0099] An amorphous LLZO film with partial substitution by aluminum
was prepared by mixing a sol gel precursor solution, depositing the
solution by spin coating, gelling, drying and curing of the spin
coated film. The ionic conductivity of the film was then
measured.
[0100] The sol gel precursor solution was prepared by mixing in an
inert environment 10 grams of methoxyethanol (2ME) with 9 grams of
lanthanum methoxyethoxide solution (about 12% by weight in
methoxyethanol (LaMOE-2ME), 1.32 grams of lithium butoxide (LiOBu),
1.53 grams zirconium butoxide solution (ZrOBu, about 80% by weight
in butanol) and 1 gram of aluminum t-butoxide. The sol gel
precursor solution was deposited as a film on a glass substrate
with sputtered aluminum bars by spin coating in a low humidity,
ozone rich air environment. The just deposited sol gel film was
exposed to the low humidity, ozone rich air environment for about 1
hour, followed by heating the substrate and film at 80.degree. C.
in the low humidity, ozone rich air environment for about 45
minutes and then heating the substrate and film at 135.degree. C.
in the low humidity, ozone rich air environment for about 45
minutes. The curing of the sol gel film was completed by heating
the substrate and film at about 300.degree. C. in air for about 1
hour.
[0101] Gold bars were sputtered on top of the sol gel deposited
film in an orientation perpendicular to the Al bars to form the
second electrode for conductivity measurements. The ionic
conductivity was measured by electrochemical impedance spectroscopy
(EIS) using a Solartron SI 1260 Impedance Analyzer instrument in
the frequency range from 32 MHz to 1Hz. The ionic conductivity was
estimated from the value of the high frequency intercept of the
Nyquist plot of the EIS spectra. FIGS. 3 and 4 show the Nyquist
plot of the measured EIS spectra; FIG. 3 showing the whole
spectrum, indicating pure ionic conduction of the film, and FIG. 4,
focusing on the high frequency real axis intercept. The ionic
conductivity of the amorphous LLZO film with partial substitution
by aluminum and prepared by sol gel was estimated to be 1.4E-4
S/cm.
Example 4
Preparation and Analysis of Amorphous LLZO by Sol Gel with Partial
Substitution by Barium
[0102] An amorphous LLZO film with partial substitution by barium
was prepared as described in Example 3 with the exception of the
amount and type of the metal precursors in the sol gel precursor
solution. A solution was prepared with 6 grams of LaMOE-2ME, 1.32
grams of LiOBu, 1.53 grams of ZrOBu and 1 gram of barium
methoxypropoxide solution (about 25% by weight in methoxypropanol).
The Nyquist plot was similar to the Nyquist plot for Example 4,
indicating pure ionic conduction. The ionic conductivity of the
amorphous LLZO film with partial substitution by barium and
prepared by sol gel was estimated to be 1.8E-4 S/cm.
Example 5
Amorphous LLZO by Sol Gel with Partial Substitution by Tantalum
(a)
[0103] An amorphous LLZO film with partial substitution by tantalum
was prepared as described in Example 3 with the exception of the
amount and type of the metal precursors in the sol gel precursor
solution. A solution was prepared with 9 grams of LaMOE-2ME, 1.32
grams of LiOBu, 1.13 grams of ZrOBu and 0.47 grams of tantalum
ethoxide. The Nyquist plot was similar to the Nyquist plot for
Example 3, indicating pure ionic conduction. The ionic conductivity
of the amorphous LLZO film with partial substitution by tantalum
and prepared by sol gel was estimated to be 3.9E-4 S/cm.
Example 6
Amorphous LLZO by Sol Gel with Partial Substitution by Tantalum
(b)
[0104] An amorphous LLZO film with partial substitution by tantalum
was prepared as described in Example 3 with the exception of the
amount and type of the metal precursors in the sol gel precursor
solution. A solution was prepared with 9 grams of LaMOE-2ME, 1.32
grams of LiOBu, 1.25 grams of ZrOBu and 0.35 grams of tantalum
butoxide. The Nyquist plot was similar to the Nyquist plot for
Example3, indicating pure ionic conduction. The ionic conductivity
of the amorphous LLZO film with partial substitution by tantalum
and prepared by sol gel was estimated to be 4.1E-4 S/cm.
Example 7
Amorphous LLZO by Sol Gel with Partial Substitution by Niobium
[0105] An amorphous LLZO film with partial substitution by niobium
was prepared as described in Example 3 with the exception of the
amount and type of the metal precursors in the sol gel precursor
solution. A solution was prepared with 9 grams of LaMOE-2ME, 1.32
grams of LiOBu, 1.20 grams of ZrOBu and 0.40 grams of niobium
butoxide. The Nyquist plot was similar to the Nyquist plot for
Example 3, indicating pure ionic conduction. The ionic conductivity
of the amorphous LLZO film with partial substitution by niobium and
prepared by sol gel was estimated to be 6.8E-4 S/cm.
Example 8
Amorphous LLZO by Sol Gel with Addition of Acetylacetone
[0106] An amorphous LLZO film with added acetylacetone as a gelling
and curing control agent was prepared by mixing of a sol gel
precursor solution, deposition of the solution by spin coating,
gelling, drying, and curing of the spin coated film. The ionic
conductivity of the film was then measured.
[0107] The sol gel precursor solution was prepared by mixing in an
inert environment 10 grams of methoxyethanol (2ME) with 9 grams of
lanthanum methoxyethoxide solution (about 12% by weight in
methoxyethanol (LaMOE-2ME), 1.32 grams of lithium butoxide (LiOBu),
1.53 grams zirconium butoxide solution (ZrOBu, about 80% by weight
in butanol) and 0.55 grams of acetylacetone. The sol gel precursor
solution was deposited as a film on a glass substrate with
sputtered aluminum bars by spin coating in a low humidity, ozone
rich air environment. The just deposited sol gel film was exposed
to the low humidity, ozone rich air environment for about 1 hour,
followed by heating the substrate and film at 80.degree. C. in the
low humidity, ozone rich air environment for about 45 minutes and
then heating the substrate and film at 135.degree. C. in the low
humidity, ozone rich air environment for about 45 minutes. The
curing of the sol gel film was completed by heating the substrate
and film at about 300.degree. C. in air for about 1 hour.
[0108] Gold bars were sputtered on top of the sol gel deposited
film in an orientation perpendicular to the Al bars to form the
second electrode for the conductivity measurements. The ionic
conductivity was measured by electrochemical impedance spectroscopy
(EIS) using Solartron SI 1260 Impedance Analyzer instrument in the
frequency range from 32 MHz to 1Hz. The ionic conductivity was
estimated from the value of the high frequency intercept of the
Nyquist plot of the EIS spectra. FIGS. 6 and 7 show the Nyquist
plot of the measured EIS spectra; FIG. 6 showing the whole spectrum
indicating pure ionic conduction of the film and FIG. 7 focusing on
the high frequency real axis intercept. The ionic conductivity of
the amorphous LLZO film with addition of acetone and prepared by
sol gel was estimated to be 5.2E-5 S/cm.
Example 9
Amorphous LLZO by Sol Gel with Lithium Acetylacetonate
[0109] An amorphous LLZO film using lithium acetylacetonate as
lithium precursor was prepared as described in Example 8 with the
exception of the amount and type of the metal precursors in the sol
gel precursor solution. A solution was prepared with 9 grams of
LaMOE-2ME, 1.75 grams of lithium acetylacetonate and 1.53 grams of
ZrOBu. The Nyquist plot was similar to the Nyquist plot for Example
8, indicating pure ionic conduction. The ionic conductivity of the
amorphous LLZO film using lithium acetylacetonate as lithium
precursor and prepared by sol gel was estimated to be 1.4E-4 S/cm.
Thus, lithium acetylacetonate (acac) is a suitable lithium
precursor. It is expected that other metal acac compounds and other
metal .beta.-diketonates may also be used as metal precursors for
the sol gel precursor solutions utilized in the method of the
invention.
Example 10
Amorphous LLZO by Sol Gel with Addition of Ethanol
[0110] An amorphous LLZO film prepared using a different solvent
mixture was prepared as described in Example 8 with the exception
of the amount and type of the metal precursors in the sol gel
precursor solution. A solution was prepared with 2 grams of 2ME,
1.8 grams of LaMOE-2ME, 0.26 grams of LiOBu, 0.31 grams of ZrOBu
and 0.37 grams of ethanol. The ethanol was included in the solution
in order to help control the sol gel gellation and curing
processes. The Nyquist plot was similar to the Nyquist plot for
Example 8, indicating pure ionic conduction. The ionic conductivity
of the amorphous LLZO film with added ethanol and prepared by sol
gel was estimated to be 1.6E-4 S/cm.
Example 11
Amorphous LLZO by Sol Gel with Addition of Ethanol and Water
[0111] An amorphous LLZO film prepared using a different solvent
mixture was prepared as described in Example 8 with the exception
of the amount and type of the metal precursors in the sol gel
precursor solution. A solution was prepared with 2 grams of 2ME,
1.8 grams of LaMOE-2ME, 0.26 grams of LiOBu, 0.31 grams of ZrOBu
and a water/ethanol solution containing 6.6 milligrams of water and
0.31 grams of ethanol that had been mixed prior to the preparation
of the sol gel precursor solution. The ethanol/water solution was
included in order to help control the sol gel gellation and curing
processes. The Nyquist plot was similar to the Nyquist plot for
Example 8, indicating pure ionic conduction. The ionic conductivity
of the amorphous LLZO film with water in ethanol added and prepared
by sol gel was estimated to be 3.6E-4 S/cm.
[0112] Many variations and modifications may be made to the
above-described embodiments without departing from the scope of the
claims. All such modifications, combinations, and variations are
included herein by the scope of this disclosure and the following
claims.
[0113] The composition described herein is amorphous lithium
lanthanum zirconium oxide (LLZO). It is ionically conductive and,
if electronically conductive at all, only negligibly so. When
formed as a thin layer, the amorphous LLZO is an effective
electrolyte medium that is useful in an electrochemical cell in
which lithium is employed as electrode material. The amorphous LLZO
electrolyte medium is non-aqueous, non-liquid, inorganic, and
non-reactive with lithium; will not leak or leach with respect to
adjacent components of a battery cell; and can be manufactured in
flexible, thin, useful layers.
[0114] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *