U.S. patent application number 12/683514 was filed with the patent office on 2010-06-03 for resistance-stabilizing additives for electrolyte.
This patent application is currently assigned to Medtronic, Inc.. Invention is credited to Donald R. Merritt, Craig L. Schmidt.
Application Number | 20100136426 12/683514 |
Document ID | / |
Family ID | 38267955 |
Filed Date | 2010-06-03 |
United States Patent
Application |
20100136426 |
Kind Code |
A1 |
Merritt; Donald R. ; et
al. |
June 3, 2010 |
RESISTANCE-STABILIZING ADDITIVES FOR ELECTROLYTE
Abstract
A resistance-stabilizing additive to an electrolyte for a
battery cell in an implantable medical device is presented. At
least one resistance-stabilizing additive is selected from a group
comprising an electron withdrawing group, an aromatic diacid salt,
an inorganic salt, an aliphatic organic acid, an aromatic diacid,
and an aromatic monoacid.
Inventors: |
Merritt; Donald R.;
(Brooklyn Center, MN) ; Schmidt; Craig L.; (Eagan,
MN) |
Correspondence
Address: |
MUETING, RAASCH & GEBHARDT, P.A.
P.O. BOX 581336
MINNEAPOLIS
MN
55458-1336
US
|
Assignee: |
Medtronic, Inc.
Minneapolis
MN
|
Family ID: |
38267955 |
Appl. No.: |
12/683514 |
Filed: |
January 7, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11344376 |
Jan 31, 2006 |
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12683514 |
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Current U.S.
Class: |
429/200 ;
429/188; 429/203 |
Current CPC
Class: |
H01M 10/0567 20130101;
Y02E 60/10 20130101 |
Class at
Publication: |
429/200 ;
429/188; 429/203 |
International
Class: |
H01M 6/04 20060101
H01M006/04 |
Claims
1. A resistance-stabilizing additive for an electrolyte of a
battery cell in an implantable medical device (IMD) comprising: at
least one chemical compound selected from a chemical class
consisting of an electron withdrawing group, an aromatic diacid
salt, an inorganic salt, an aliphatic organic acid, an aromatic
diacid, and an aromatic monoacid.
2. The additive of claim 1 wherein the electron-withdrawing group
selected from one of trifluoromethylvinyl acetate and
2,2,2-trifluoroacetamide.
3. The additive of claim 1, wherein aromatic monoacid comprises
benzoic acid.
4. The additive of claim 1, wherein the benzoic acid includes
fluorinated benzoic acid.
5. The additive of claim 1, wherein the benzoic acid being one of
3-hydroxy benzoic acid and 2-4 hydroxy benzoic acid.
6. The additive of claim 1, wherein the organic acid selected from
a group comprising carboxylic acid, benzoic acid, and
hexafluoroglutaric acid.
7. An additive to an electrolyte for use in a battery cell in an
IMD, the additive comprising: an electron-withdrawing group.
8. The additive of claim 6 wherein the electron-withdrawing group
selected from one of trifluoromethylvinyl acetate and
2,2,2-trifluoroacetamide.
9. An additive to an electrolyte for use in a battery cell in an
IMD, the additive being at least one of tetramethyl ammonium (TMA)
hydrogen phthalate, tetrabutyl-ammonium (TBA) hydrogen sulfate,
phosphonoacetic acid, 2,2,2-trifluoroacetamide, trifluoromethyl
vinyl acetate, phthalic acid, benzoylacetone,
benzoltrifluoroactone, and benzoic acid.
10. An additive composition for an electrolyte in a battery cell
for an IMD comprising: a first resistance-stabilizing additive; and
a second resistance-stabilizing additive combined with the first
resistance-stabilizing additive.
11. The additive composition of claim 10, the first
resistance-stabilizing additive being at least one of TMA hydrogen
phthalate, TBA hydrogen sulfate, phosphonoacetic acid,
2,2,2-trifluoroacetamide, trifluoromethyl vinyl acetate, phthalic
acid, benzoylacetone, benzoltrifluoroactone, and benzoic acid.
12. The additive composition of claim 10, the second
resistance-stabilizing additive being at least one of TMA hydrogen
phthalate, TBA hydrogen sulfate, phosphonoacetic acid,
2,2,2-trifluoroacetamide, trifluoromethyl vinyl acetate, phthalic
acid, benzoylacetone, benzoltrifluoroactone, and benzoic acid.
13. The additive composition of claim 10, further comprising: a
third resistance-stabilizing additive, the third
resistance-stabilizing additive being at least one of TMA hydrogen
phthalate, TBA hydrogen sulfate, phosphonoacetic acid,
2,2,2-trifluoroacetamide, trifluoromethyl vinyl acetate, phthalic
acid, benzoylacetone, benzoltrifluoroactone, and benzoic acid.
14. A method for forming an additive composition for an electrolyte
in a battery cell for an IMD, the method comprising: selecting a
first resistance-stabilizing additive; and combining a second
resistance-stabilizing additive with the first
resistance-stabilizing additive to form a resistance-stabilizing
composition.
15. The method of claim 14, further comprising: combining the
resistance-stabilizing composition with a base electrolyte
composition for the battery cell.
16. The method of claim 14, the first resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoltrifluoroactone, and benzoic acid.
17. The method of claim 14, the second resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoltrifluoroactone, and benzoic acid.
18. An electrolyte comprising a base liquid electrolyte composition
and a resistance-stabilizing additive distinct from the base liquid
electrolyte composition, wherein the resistance-stabilizing
additive comprises at least one chemical compound selected from a
chemical class consisting of a compound comprising an electron
withdrawing group, an aromatic diacid salt, an inorganic salt, an
aliphatic organic acid, an aromatic diacid, and an aromatic
monoacid.
19. The electrolyte of claim 18, wherein the resistance-stabilizing
additive comprises a compound comprising an electron-withdrawing
group that is selected from one of trifluoromethylvinyl acetate and
2,2,2-trifluoroacetamide.
20. The electrolyte of claim 18, wherein the resistance-stabilizing
additive comprises an aromatic monoacid that comprises a benzoic
acid.
21. The electrolyte of claim 20, wherein the benzoic acid includes
fluorinated benzoic acid.
22. The electrolyte of claim 20, wherein the benzoic acid is
selected from one of 3-hydroxy benzoic acid and 2-4 hydroxy benzoic
acid.
23. The electrolyte of claim 18, wherein the resistance-stabilizing
additive comprises an organic acid that is selected from a group
comprising carboxylic acid, benzoic acid, and hexafluoroglutaric
acid.
24. An electrolyte comprising a base liquid electrolyte composition
and a resistance-stabilizing additive distinct from the base liquid
electrolyte composition, wherein the resistance-stabilizing
additive comprises a compound having an electron-withdrawing
group.
25. The electrolyte of claim 24, wherein the compound having an
electron-withdrawing group comprises 2,2,2-trifluoroacetamide.
26. An electrolyte comprising a base liquid electrolyte composition
and a resistance-stabilizing additive distinct from the base liquid
electrolyte composition, wherein the resistance-stabilizing
additive comprises at least one of tetramethyl ammonium (TMA)
hydrogen phthalate, tetrabutyl-ammonium (TBA) hydrogen sulfate,
phosphonoacetic acid, 2,2,2-trifluoroacetamide, trifluoromethyl
vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
27. An electrolyte comprising: a base liquid electrolyte
composition; a first resistance-stabilizing additive; and a second
resistance-stabilizing additive combined with the first
resistance-stabilizing additive; wherein the first and second
resistance-stabilizing additives are distinct from the base liquid
electrolyte composition.
28. The electrolyte of claim 27, the first resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
29. The electrolyte of claim 27, the second resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
30. The electrolyte of claim 27, further comprising: a third
resistance-stabilizing additive, the third resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
31. A method for forming an electrolyte in a battery cell for an
implantable medical device, the method comprising: selecting a
first resistance-stabilizing additive; combining a second
resistance-stabilizing additive with the first
resistance-stabilizing additive to form a resistance-stabilizing
composition; and combining the resistance-stabilizing composition
with a base electrolyte composition for the battery cell.
32. The method of claim 31, the first resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
33. The method of claim 31, the second resistance-stabilizing
additive being at least one of TMA hydrogen phthalate, TBA hydrogen
sulfate, phosphonoacetic acid, 2,2,2-trifluoroacetamide,
trifluoromethyl vinyl acetate, phthalic acid, benzoylacetone,
benzoyltrifluoroacetone, and benzoic acid.
34. A battery comprising an electrode assembly and an electrolyte,
wherein the electrolyte comprises a liquid electrolyte and a
resistance-stabilizing additive distinct from the liquid
electrolyte, wherein the resistance-stabilizing additive comprises
at least one chemical compound selected from a compound comprising
an electron withdrawing group, an aromatic diacid salt, an
inorganic salt, an aliphatic organic acid, an aromatic diacid, an
aromatic monoacid, and combinations thereof.
35. The battery of claim 34, wherein the resistance-stabilizing
additive comprises compound comprising an electron-withdrawing
group.
36. An implantable medical device comprising the battery of claim
34.
37. A battery comprising an electrode assembly and an electrolyte,
wherein the electrolyte comprises a liquid electrolyte and a
resistance-stabilizing additive distinct from the liquid
electrolyte, the additive being at least one of TMA hydrogen
phthalate, TBA hydrogen sulfate, phosphonoacetic acid,
2,2,2-trifluoroacetamide, trifluoromethyl vinyl acetate, phthalic
acid, benzoylacetone, benzoyltrifluoroacetone, and benzoic
acid.
38. An implantable medical device comprising the battery of claim
37.
39. A battery comprising an electrode assembly and an electrolyte,
wherein the electrolyte comprises a liquid electrolyte and a
resistance-stabilizing additive composition distinct from the
liquid electrolyte, the additive composition comprising: a first
resistance-stabilizing additive; and a second
resistance-stabilizing additive combined with the first
resistance-stabilizing additive.
40. An implantable medical device comprising the battery of claim
39.
Description
RELATED APPLICATION
[0001] This application is related to, and claims the benefit of,
U.S. patent application Ser. No. 10/876,003 filed Feb. 13, 2003
entitled "Liquid Electrolyte For An Electrochemical Cell,
Electrochemical Cell And Implantable Medical Device", which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention generally relates to an
electrochemical cell and, more particularly, to an additive in an
electrolyte for a battery.
BACKGROUND OF THE INVENTION
[0003] Implantable medical devices (IMDs) detect and treat a
variety of medical conditions in patients. IMDs include implantable
pulse generators (IPGs) or implantable cardioverter-defibrillators
(ICDs) that deliver electrical stimuli to tissue of a patient. ICDs
typically comprise, inter alia, a control module, a capacitor, and
a battery that are housed in a hermetically sealed container. When
therapy is required by a patient, the control module signals the
battery to charge the capacitor, which in turn discharges
electrical stimuli to tissue of a patient.
[0004] The battery includes a case, a liner, and an electrode
assembly. The liner surrounds the electrode assembly to prevent the
electrode assembly from contacting the inside of the case. The
electrode assembly comprises an anode and a cathode with a
separator therebetween. In the case wall or cover is a fill port or
tube that allows introduction of electrolyte into the case. The
electrolyte is a medium that facilitates ionic transport and forms
a conductive pathway between the anode and cathode. An
electrochemical reaction between the electrodes and the electrolyte
causes charge to be stored on each electrode. The electrochemical
reaction also creates a solid electrolyte interphase (SEI) or
passivation film on a surface of an anode such as a lithium anode.
The passivation film is ionically conductive and prevents parasitic
loss of lithium. However, the passivation film increases internal
resistance which reduces the power capability of the battery. It is
desirable to reduce internal resistance associated with the
passivation film for a battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0006] FIG. 1 is a cutaway perspective view of an implantable
medical device (IMD);
[0007] FIG. 2 is a cutaway perspective view of a battery in the IMD
of FIG. 1;
[0008] FIG. 3 is an enlarged view of a portion of the battery
depicted in FIG. 2 and designated by line 4.
[0009] FIG. 4 is a cross-sectional view of an anode and a
passivation film;
[0010] FIG. 5 is graph that compares discharge and resistance for a
conventional and exemplary additive in an electrolyte;
[0011] FIG. 6 is graph that compares resistance over time for
exemplary additives to an electrolyte;
[0012] FIG. 7 is a flow diagram for forming an electrolyte for a
battery; and
[0013] FIG. 8 is a flow diagram for autoclaving a battery.
DETAILED DESCRIPTION
[0014] The following description of embodiments is merely exemplary
in nature and is in no way intended to limit the invention, its
application, or uses. For purposes of clarity, the same reference
numbers are used in the drawings to identify similar elements.
[0015] The present invention is directed to an additive for an
electrolyte. The additive stabilizes resistance of the battery
during storage, thermal processing, and throughout discharge. A
resistance-stabilizing additive is defined as one or more chemical
compounds, added to an electrolyte, that causes a battery to
exhibit low resistance (i.e. generally below 500 ohm centimeter
(cm).sup.2) throughout the battery's useful life. In one
embodiment, the additive is characterized by an electron
withdrawing group. Exemplary chemical compounds containing electron
withdrawing group include 2,2,2-trifluoroacetamide, and benzoyl
acetone. In another embodiment, an organic acid serves as a
resistance-stabilizing additive. Exemplary organic acids include
benzoic acids, carboxylic acids, malic acid, tetramethylammonium
(TMA) hydrogen phthalate and hexafluoroglutaric acid.
[0016] A battery that includes an exemplary additive may be
autoclaved at 125.degree. C. for a half an hour, defined as one
cycle, performed three times without adversely affecting the
battery. The additives may be used in low, medium, or high capacity
batteries.
[0017] FIG. 1 depicts an implantable medical device (IMD) 10. IMD
10 includes a case 50, a control module 52, a battery 54 (e.g.
organic electrolyte battery) and capacitor(s) 56. Control module 52
controls one or more sensing and/or stimulation processes from IMD
10 via leads (not shown). Battery 54 includes an insulator 58
disposed therearound. Battery 54 charges capacitor(s) 56 and powers
control module 52.
[0018] FIGS. 2 and 3 depict details of an exemplary organic
electrolyte battery 54. Battery 54 includes a case 70, an anode 72,
separators 74, a cathode 76, a liquid electrolyte 78, and a
feed-through terminal 80. Cathode 76 is wound in a plurality of
turns, with anode 72 interposed between the turns of the cathode
winding. Separator 74 insulates anode 72 from cathode 76 windings.
Case 70 contains the liquid electrolyte 78 to create a conductive
path between anode 72 and cathode 76. Electrolyte 78, which
includes an additive, serves as a medium for migration of ions
between anode 72 and cathode 76 during an electrochemical reaction
with these electrodes.
[0019] Anode 72 is formed of a material selected from Group IA, IIA
or IIIB of the periodic table of elements (e.g. lithium, sodium,
potassium, etc.), alloys thereof or intermetallic compounds (e.g.
Li--Si, Li--B, Li--Si--B etc.). Anode 72 comprises an alkali metal
(e.g. lithium, etc.) in metallic or ionic form.
[0020] Cathode 76 may comprise metal oxides (e.g. vanadium oxide,
silver vanadium oxide (SVO), manganese dioxide (MnO.sub.2) etc.),
carbon monofluoride and hybrids thereof (e.g., CF.sub.x+MnO.sub.2),
combination silver vanadium oxide (CSVO) or other suitable
compounds.
[0021] Electrolyte 78 chemically reacts with anode 72 to form an
ionically conductive passivation film 82 on anode 72, as shown in
FIG. 4. Electrolyte 78 includes a base liquid electrolyte
composition and at least one resistance-stabilizing additive
selected from Table 1 presented below. The base electrolyte
composition typically comprises 1.0 molar (M) lithium
tetrafluoroborate (1-20% by weight), gamma-butyrolactone (50-70% by
weight), and 1,2-dimethoxyethane (30-50% by weight). In one
embodiment, resistance-stabilizing additives are directed to
chemical compounds that include electron withdrawing groups. An
exemplary chemical compound with an electron withdrawing group
includes 2,2,2-trifluoroacetamide. In another embodiment, the
additive is a proton donor such as an organic acid. One type of
organic acid is benzoic acid (e.g. 3-hydroxy benzoic acid or 2-4
hydroxy benzoic acid etc.). Every combination of benzoic acid and
hydroxyl benzoic acids that exists may be used as a
resistance-stabilizing additive composition. Malic acid and
tetramethylammonium hydrogen phthalate are other organic acids that
may serve as a resistance-stabilizing additive.
[0022] Tables 1 and 2 list some exemplary resistance-stabilizing
additives. In particular, Table 1 ranks each additive as to its
effectiveness with a rank of 1 being the highest or best additive
and rank 6 being the lowest ranked additive. Table 1 also briefly
describes the time period in which battery 54, which included the
specified additive in the electrolyte 78, exhibited
resistance-stabilizing characteristics.
TABLE-US-00001 TABLE 1 List of exemplary additive
resistance-stabilizing additives Chemical Exemplary additive Rank
class compound Chemical Structure Notes 3 Aromatic diacid salts
Tetramethyl- ammonium (TMA) hydrogen phthalate ##STR00001## Battery
exhibited excellent resistance- stabilizing characteristic during
storage Battery exhibited good to neutral resistance- stabilizing
characteristic during discharge 6 Inorganic acid salts Tetrabutyl-
ammonium (TBA) hydrogen sulfate ##STR00002## Battery exhibited good
resistance- stabilizing characteristic during storage Battery
exhibited neutral resistance- stabilizing characteristic during
discharge 5 Aliphatic organic acids Phosphonoacetic acid
##STR00003## Battery exhibited excellent resistance- stabilizing
characteristic during storage Battery exhibited good to neutral
resistance- stabilizing characteristic during discharge 1 (*)
2,2,2- Trifluoroacetamide ##STR00004## Battery exhibited excellent
resistance- stabilizing characteristic during storage and discharge
(*) Trifluoromethyl vinyl acetate ##STR00005## Battery exhibited
very good resistance- stabilizing characteristic during discharge 4
Aromatic diacids Phthalic acid ##STR00006## Battery exhibited good
resistance- stabilizing characteristic during storage and discharge
(*) Benzoylacetone ##STR00007## Battery exhibited good resistance-
stabilizing characteristic during storage and discharge (*)
Benzoyltrifluoro- acetone ##STR00008## Battery exhibited good
resistance- stabilizing characteristic during storage and discharge
2 Aromatic mono- acids Benzoic acid ##STR00009## Battery exhibited
excellent resistance- stabilizing characteristic during storage and
discharge
(*) These compounds include a chemical structure that is
characterized by one or more electron-withdrawing groups (e.g.
--CF.sub.3, --C.sub.6H.sub.5 located one or two carbon atoms from a
double-bonded oxygen atom (i.e. a ketone group)). Additionally, the
listed additives may be added to the base electrolyte composition
in the range of about 0.001M to 0.5M.
[0023] Table 2 lists exemplary additive compositions that are mixed
with the base electrolyte composition to produce effective
resistance-stabilization in battery 54. Effective additive
compositions are based upon additives that exhibit superior
resistance-stabilizing characteristics either at the beginning of
life (BOL) or at the end of life (EOL) of battery 54. In one
embodiment, an additive composition comprises a first additive that
exhibits substantially superior resistance-stabilizing
characteristics at the BOL whereas a second additive exhibits
substantially superior resistance-stabilizing characteristics at
the EOL. In another embodiment, a first resistance-stabilizing
additive exhibits a substantially superior resistance-stabilizing
characteristics at the BOL whereas a second resistance-stabilizing
additive exhibits average resistance-stabilizing characteristics at
the EOL. In still yet another embodiment, a first
resistance-stabilizing additive exhibits substantially superior
resistance-stabilizing characteristics at the EOL whereas a second
resistance-stabilizing additive exhibits average
resistance-stabilizing characteristics at the BOL. Generally, each
additive is combined with the electrolyte 78 through dissolution or
other suitable means.
TABLE-US-00002 TABLE 2 Exemplary resistance-stabilizing composition
additives Additive compositions Quantity of each additive TMA
hydrogen phthalate + About 0.001 M to about 0.5M
2,2,2-Trifluoroacetamide TMA hydrogen phthalate + About 0.001 M to
about 0.5M Trifluoromethyl vinyl acetate TMA hydrogen phthalate +
About 0.001 M to about 0.5M Acetone TMA hydrogen phthalate + About
0.001 M to about 0.05M Xylitol Phosphonoacetic acid + About 0.001 M
to about 0.5M 2,2,2-Trifluoroacetamide Phosphonoacetic acid + About
0.001 M to about 0.5M Trifluoromethyl vinyl acetate Phosphonoacetic
acid + About 0.001 M to about 0.5M Acetone Phosphonoacetic acid +
About 0.001 M to about 0.5M Xylitol
[0024] FIGS. 5-6 graphically depict the resistance-stabilizing
superiority of electrolyte 78 over a control electrolyte 88.
Electrolyte 78 includes 2,2,2-trifluoroacetamide as the
resistance-stabilizing additive and the base electrolyte
composition previously described. Control electrolyte 88 is the
base electrolyte composition without any additive. Passivation
layer 82 initially possesses similar discharge to passivation layer
formed by control electrolyte 88. However, later in the discharge
(e.g. about 0.90 amperehour(Ah)), the passivation layer formed by
control electrolyte 88 exhibits resistance that substantially
increases. In contrast, electrolyte 78 that includes the additive
causes battery 54 to exhibit resistance that remains substantially
below the resistance of control electrolyte 88 late in discharge.
For example, electrolyte 78 results in battery 54 having 30 ohms
lower resistance than control electrolyte 88, as show in FIG.
5.
[0025] If the resistance increases in the area between 1 and 1.2 Ah
of the curve and IMD 10 records the voltage after a high current
event (e.g. telemetry event etc.), a recommended replacement time
(RRT) signal may be generated. Preferably, desirable resistance is
kept low as long as possible to increase efficiency of battery
54.
[0026] FIG. 7 depicts a method for forming a resistance-stabilizing
additive composition. At operation 200, a first resistance
stabilizing additive is selected. At operation 210, the first
resistance stabilizing additive is combined with a second
resistance stabilizing additive to create a resistance stabilizing
composition.
[0027] FIG. 8 depicts a method for autoclaving battery cell 54.
Battery cell 54 is inserted into a chamber of an autoclave at
operation 300. Battery cell 54 includes an electrolyte and a first
resistance-stabilizing additive combined with the electrolyte. At
block 310, heat is applied to the chamber of the autoclave.
Generally, the autoclaving process occurs at a temperature of
125.degree. C. for a half an hour per cycle. The autoclave cycle is
repeated at least three times. After three cycles of autoclaving,
battery cell 54 adequately operates.
[0028] The following patent application is incorporated by
reference in its entirety. Co-pending U.S. patent application Ser.
No. XXXXXXXX, entitled "ELECTROLYTE ADDITIVE FOR PERFORMANCE
STABILITY OF BATTERIES", filed by Kevin Chen, Donald Merritt and
Craig Schmidt and assigned to the same Assignee of the present
invention, describes resistance-stabilizing additives for
electrolyte.
[0029] Although various embodiments of the invention have been
described and illustrated with reference to specific embodiments
thereof, it is not intended that the invention be limited to such
illustrative embodiments. For example, while an additive
composition is described as a combination of two additives, it may
also include two or more additives selected from Table 1. The
description of the invention is merely exemplary in nature and,
thus, variations that do not depart from the gist of the invention
are intended to be within the scope of the invention. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention.
* * * * *