Unite States
i atent [191
[1 1]
[45]
Domeniconi et a1.
[54] ELECTROCHEMICAL CELL AND
ELECTROLYTIC SOLUTION THEREFOR
[75] Inventors: Michael J. Domeniconi, Santa Clara,
Calif.; Carl R. Schlaikjer,
Winchester; Clifton A. Young,
Bedford, both of Mass. '
[73] Assignee: GTE Laboratories Incorporated,
Waltharn, Mass.
4,3,021
Sep. 6, 1983
3,926,669 12/1975
Aubom ............................. .. 429/196
4,012,564
3/1977
Auborn
4,020,240
4/1977
Schlaikjer .................. .. 429/ 199
.. . ..
Electrochemical Society, Princeton, vol. 79-1, pp.
348—355, 1979.
Primary Examiner-Anthony Skapars
[22] Filed:
Attorney, Agent, or Firm—-David M. Keay
[57]
Related US. Application Data
[63]
Continuation of Ser. No. 147,985, May 8, 1980, aban
doned.
[51]
[52]
[58]
1111.01; ............................................ .. H01M 6/16
us. (:1. .................................. .. 429/101; 429/196;
429/ 194
OTHER PUBLICATIONS
Gabano et a1., “Lithium Thionyl Chloride Bobbin Cells:
Present Status and Performance”, Proceedings of the
Symposium on Battery Design, and Optimization, The
[21] Appl. No.: 447,049
Dec. 6, 1982
. . . . ..
ABSTRACT
An electrochemical cell having an oxidizable anode
containing lithium and a cathode current collector. The
cell includes an electrolytic solution in contact with the
anode and the cathode current collector, The solution
includes a solvent which is also a reducible liquid cath
429/199
ode material, speci?cally SOClg, and an electrolyte
Field of Search ............. .. 429/101, 196, 197,199,
solute consisting of the reaction products of a salt of an
429/2oo,194
oxyacid, speci?cally Li2SO3, constituting a Lewis base
[56]
and a Lewis acid, speci?cally AlCl3, dissolved in the
solvent.
References Cited
U.S. PATENT DOCUMENTS
3,567,515
3/1971
11 Claims, 4 Drawing Figures
Maricle et a1. ............... .. 429/197 X
16
1M mm3 +EXCESS 1.12 503
14
1.0M LlAICI4
10
Qx'1(cCOmN0D'UK13TI)VY
0.5M Liz 510C110
0.5M Li2(AICl3OAlCl3)
2_
4M A1013
TEMPERATURE (°C)
US. Patent
Sep. 6, 1983
10
Sheet 2 of2
2O
4,403,021
30
40
TIME (SECONDS)
-
.
FI‘Lg'. 3.
3.0 ——
21
o.
3O
TIME (SECONDS)
40
-
F ‘Lg. 4.
4,403,021
1
2
SUMMARY OF THE INVENTION
ELECTROCHEMICAL CELL AND
ELECTROLYTIC SOLUTION THEREFOR
An improved electrolytic solution in accordance
with the present invention includes a solvent and an
This is a continuation of application Ser. No. 147,985, 5 electrolyte solute consisting of the reaction products of
a salt of an oxyacid which constitutes a Lewis base
?led May 8, 1980, now abandoned.
together with a Lewis acid dissolved in the solvent. An
BACKGROUND OF THE INVENTION
electrochemical cell in accordance with the present
This invention relates to electrochemical cells. More 10 invention employs the electrolytic solution in combina
tion with an oxidizable anode material and a reducible
particularly, it is concerned with electrochemical cells
cathode material. The solvent may include the reduc
employing non-aqueous electrolytic solutions and to
ible cathode material in liquid form. Cells in accordance
electrolytic solutions therefor.
with the invention provide satisfactory startup charac
A particularly effective class of electrochemical cells
teristics
without undesirable consequences.
which employs soluble or liquid cathode materials has
undergone rapid development in recent years. In these
BRIEF DESCRIPTION OF THE DRAWINGS
cells the active cathode material is usually a fluid sol
In the drawings:
vent for an electrolyte solute which provides conduc
FIG. 1 is a graph illustrating the conductivity of an
tivity. The active anode for these cells is usually lithium
electrolytic solution in accordance with the present
or other highly electropositive metal. During discharge
20
the solvent is electrochemically reduced on a cathode
current collector to yield ions, e.g., halide ions, which
react with positive metals ions from the anode to form
invention in comparison with other solutions;
FIG. 2 is an elevational view partially in cross section
of an electrochemical cell in accordance with the pres
ent invention;
FIG. 3 is a graph illustrating the startup characteris
One particular type of electrochemical cell of the 25 tics of electrochemical cells of previously known type;
and
foregoing class which contains a lithium anode employs
FIG. 4 is a graph illustrating the startup characteris
a reducible liquid cathode of thionyl chloride. Typically
tics of electrochemical cells in accordance with the
the electrolyte solute dissolved in the thionyl chloride
present invention.
solvent is lithium tetrachloroaluminate. This salt is pre
For a better understanding of the present invention,
pared from the Lewis acid aluminum chloride and the 30
together with other and further objects, advantages,
Lewis base lithium chloride. A Lewis acid is any com
and capabilities thereof, reference is made to the follow
pound capable of entering into a chemical reaction by
ing discussion and appended claims in connection with
accepting an electron pair to form a covalent bond, and
the above described drawings.
a Lewis base is any compound capable of entering into
a chemical reaction by donating an electron pair to form
DETAILED DESCRIPTION OF THE
insoluble metal salts, e.g., meta] halides.
'
a covalent bond. Lithium/thionyl chloride electro
INVENTION
chemical coils have proven to have outstanding weight
and volume energy density, long shelf life, and unusu
lytic solutions containing an electrolyte salt produced
The present invention relates to non-aqueous electro
ally high power density when compared with other
cells presently available.
Under unfavorable circumstances during prolonged
40 by the reaction of a salt of an oxyacid which constitutes
storage or storage under extreme conditions, corrosion
tion provide a cation of an alkali metal, alkaline earth
a Lewis base with a Lewis acid. Salts of oxyacids which
may be employed in electrolytic solutions of the inven
of the lithium anode in a cell causes a ?lm of lithium
metal, ammonium, alkyl ammonium, pyridinium, alkyl
chloride and grow on the anode suf?cient to cause 45 pyridinium, scandium, yttrium, or a rare earth. Suitable
signi?cant polarization at the onset of discharge of the
cell. After operating at a reduced potential for a period
of time, a cell may recover depending upon the severity
oxyacid salts provide an anion such as orthoborate,
metaborate, aluminate, C0321 SiO32—, GeO32—,
SnO32_, N031 PO33_, PO43—, ASO33_, ASO43_,
SO32_, S042", S6042“, T6042“, TeO43—, S2O4——,
S2O(,——, polythionate, thiosulfate, molybdate, phos
of the condition. This initial polarization is referred to as
voltage delay and has been found particularly trouble
phomalybdate, tungstate, ClO3—, ClO4—, BrO3—,
some in cells which are required to operate at current
BrO4‘, I03“, and I04“. 'The oxyacid salt is reacted
densities higher than 1 mA/cm2.
with a Lewis acid such as AlCl3, AlBr3, A113, BCl3,
Various attempts have been made to overcome the
problem of voltage delay upon startup. In one technique
described in US. Pat. No. 4,020,240 to Carl R.
55
BF3, BBr3, B13, PF5, AsF5, SbF5, SbCl5, SnCl4, TiCl4,
ZrCl4, GaCl3, GaFg, GaBr3, GaI3, InCl3, InF3, InBr3,
InI3, TlCl3, TlF3, SiF4, and GeCl4.
Schlaikjer dated Apr. 26, 1977, a lithium clovoborate
The solute is produced by the reaction obtained by
salt such as Li2B10Cl10 is employed as the electrolyte
dissolving the salt of an oxyacid and a Lewis acid in a
solute. In another technique described by J. P. Gabano
solvent. The solvent may be an electrochemically re
in paper #27, presented at the Electrochemical Society 60 ducible liquid such as an oxyhalide of sulfur, phospho
Fall Meeting, Pittsburgh, Oct. 15-20, 1978,‘ the electro
lyte solute is a salt prepared by dissolving lithium oxide
in thionyl chloride containing aluminum chloride. It is
postulated that the salt produced by the reaction is Liz
(AlCl3O AlCl3). Although the solutes of Schlaikjer and
Gabano provide cells having improved startup charac
teristics, either they are expensive, dif?cult to purify or
less conductive than presently used materials.
rus, or selenium. It may also be a ?uid non-metallic
oxide, or a ?uid non-metallic halide, or mixtures
thereof. Other classes of solvent which may be utilized
65
include aliphatic ethers, alicylic ethers, esters, cyclic
esters, cyclic lactones, anhydrides, nitriles, amides, and
ureas.
Electrochemical cells utilizing electrolytic solutions
in accordance with the present invention may also em
3
4,403,021
4
ploy oxidizable anode materials other than lithium. The
anode material may be another alkali metal, an alkaline
chemical cells employing an electrolytic solution in
accordance with the present invention operate at full
earth metal, scandium, yttrium, or a rare earth.
operating potential immediately upon startup without
the voltage delay problem encountered with previously
More speci?cally, an electrolytic solution particu
larly useful in electrochemical cells employing lithium
and thionyl chloride was obtained by reacting alumi
known devices.
While there has been shown and described what are
num chloride (AlCl3), a Lewis acid, with lithium sul?te
considered preferred embodiments of the present inven
(LizSO3), which constitutes a Lewis base. A 1 M solu
tion, it will be obvious to those skilled in the art that
tion of AlCl3 in SOClz was stirred while being heated
various changes and modi?cations may be made therein
under re?ux with enough solid LlgSOg, to provide a 0 without departing from the invention as de?ned by the
stoichiometric ratio of AlCl3 to Li2SO3 of 2 to 1.1. The
appended claims.
conductivity of the solution was tested at various tem
What is claimed is:
peratures and the curve of conductivity versus tempera
1. An electrochemical cell comprising
ture is plotted in FIG. 1. Curves illustrating the conduc
an oxidizable anode material;
tivity of a 1.0 M solution of LiAlCl4 in SOCl2, a 0.5 M 15
solution of Li2B10Cl10 in SOClg, and a 4 M solution of
AlClz in SOCl2 are also shown in FIG. 1. Also shown is
a curve illustrating the conductivity of a 0.5 M Li;
(AlCl3OAlCL3) solution in SOClZ. It is postulated that
this is the salt produced by dissolving LigO in SOC];
containing AlCl3 in accordance with the teachings in
a cathode current collector; and
an electrolytic solution, in contact with the anode
material and the cathode current collector, com
prising a reducible liquid cathode material and an
electrolyte solute consisting of the reaction prod
ucts of lithium sul?te and a Lewis acid dissolved in
the liquid cathode material.
the aforementioned article by Gabano. As can be seen
2. An electrochemical cell in accordance with claim 1
wherein
the lewis acid is selected from the group consisting of
from the curves of FIG. 1 the conductivity of appli
cants’ solution compares favorably with that of lithium
tetrachloroaluminate and is signi?cantly higher than 25
that of solutions containing lithium clovoborate and the
salts prepared in accordance with the technique of
Gabano.
The properties of the electrolytic solution of the pres
AlCl3, AlBr3, A113, BCl3, BF3, BBr3, B13, PF5,
AsF5, SbF5, SbCl5, SnCl4, TiCl4, ZrCl4, GaCl3,
GaF3, GaBrg, GaI3, InCl3, InF3, InBr3, InI3, TiCl3,
TiF3, SiF4, and GeCl4.
3. An electrochemical cell in accordance with claim 2
ent invention indicate that a soluble lithium salt is a 30 wherein
product of the reaction of the Li2SO3 and AlCl3 in
the reducible liquid cathode material is selected from
the group consisting of ?uid oxyhalides, ?uid non
SOClZ. It may be that the Li2SO3, acting as a Lewis
base, forms an adduct salt with the AlCl3, a Lewis acid.
Several electrochemical cells as illustrated in FIG. 2
were constructed. Some were ?lled with an electrolytic
solution containing lithium tetrachloroaluminate as a
solute and some were ?lled with an electrolytic solution
in accordance with the present invention. The cells
were about the size of commercial AA cells, approxi
mately 1% inches long and % inch in diameter. The cases
metallic oxides, ?uid non-metallic halides, and mix
tures thereof; and
the oxidizable anode material is selected from the
group consiting of alkali metals, alkaline earth met
als, scandium, yttrium, and rare earths.
4. An electrochemical cell in accordance with claim 3
wherein
40
the reducible liquid cathode material is selected from
10 were of stainless steel. Anodes 11 of lithium metal
were pressed to the inside walls of the cases 10. Concen
tric bobbin cathodes 13 of Shawinigan carbon black and
Te?on formed as an aqueous dispersion and dried were
the group consisting of oxyhalides of sulfur, phos
phorus and selenium;
the Lewis acid is aluminum chloride; and
the oxidizable anode material is lithium metal.
5. An electrochemical cell in accordance with claim 4
placed in the cases encircled by separators 12 of insulat 45
ing material. After being ?lled with an electrolytic solu
wherein
tion, each case was sealed with a cover 15 having a
the reducible liquid cathode material is thionyl chlo
conductive lead 16 to the cathode 13 through a glass-to
metal seal 17.
Some of the cells were ?lled with a 1.8 M solution of 50
LiAlCl4 in SOClZ. Other cells were ?lled with an elec
trolytic solution in accordance with the present inven
tion. The solution was prepared by re?uxing a solution
of AlCl3 in SOC]; with excess Li2SO3 for sixteen days.
The mixture was then ?ltered and diluted each that the
concentration of aluminum was reduced to about 3 M.
For both electrolytic solutions the SOCIZ solvent was
the reducible liquid cathode material of the cells.
Three cells containing LiAlCl4 as a solute and three
cells with Li2SO3 and AlCl3 were stored for four days at
72° C. The startup characteristics of these cells at room
temperature under a load of 50 ohms and current densi
ties at about 4.8 mA/cm2 were recorded. The resulting
curves of output voltage versus time for the cells em
ploying LiAlCl4 in SOCl2 are shown in FIG. 3. Output
voltage versus time for the three cells containing the
reaction products of U150; and AlCl3 in SOClg are
shown in FIG. 4. As indicated by FIGS. 3 and 4 electro
ride.
6. An electrolytic solution including in combination
a liquid electrochemically reducible solvent; and
an electrolyte solute consisting of the reaction prod
ucts of lithium sul?te and a Lewis acid dissolved in
the solvent.
7. An electrolytic solution in accordance with claim 6
wherein
Y
the liquid electrochemically reducible solvent is se
lected from the group consisting of ?uid oxyha
lides, ?uid non-metallic oxides, ?uid non-metallic
halides, and mixtures thereof.
8. An electrolytic solution in accordance with claim 6
wherein
the lewis acid is selected from the group consisting of
AlCl3, AlBr3, A113, BCl3, BF3, BBr3, B13, PF5,
AsF5, SbF5, SbCl5, SnCl4, TiCl4, ZrCl4, GaCl3,
GaF3, GaBrg, G313, InCl3, InF3, InBr3, InI3, TlCl3,
TlF3, SiF4, and GeCl4.
9. An electrolytic solution in accordance with claim 8
wherein
5
4,403,021
the liquid electrochemically reducible solvent is se-
6
lected from the group consisling of cxyhalides 0f
lected from the group consisting of ?uid oxyha-
sulfur*_pho_spl_wrus' ‘ind selemmfli and
lides, ?uid non-metallic oxides, ?uid non-metallic
the Lewis acld ls alummum chloride‘
.
.
11. An electrolytic solution in accordance with claim
halides, and mixtures thereof.
5 10 wherein
10- All electrolytic Solution in accordance with claim
the liquid electrochemically reducible solvent is thio
9 wherein
nyl chloride.
the liquid electrochemically reducible solvent is se~
*
15
20
25
35
45
55
65
*
*
*
*