U.S. patent application number 13/209357 was filed with the patent office on 2013-02-14 for rechargeable electrochemical battery cell.
This patent application is currently assigned to Fortu Intellectual Property AG. The applicant listed for this patent is Markus BORCK, Christian PSZOLLA, Christiane RIPP, Claudia WOLLFARTH, Laurent ZINCK. Invention is credited to Markus BORCK, Christian PSZOLLA, Christiane RIPP, Claudia WOLLFARTH, Laurent ZINCK.
Application Number | 20130040188 13/209357 |
Document ID | / |
Family ID | 46801451 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130040188 |
Kind Code |
A1 |
ZINCK; Laurent ; et
al. |
February 14, 2013 |
RECHARGEABLE ELECTROCHEMICAL BATTERY CELL
Abstract
Rechargeable lithium battery cell having a housing, a positive
electrode, a negative electrode and an electrolyte containing a
conductive salt, wherein the electrolyte comprises SO2 and the
positive electrode contains an active material in the composition
LixM'yM''z(XO4)aFb, wherein M' is at least one metal selected from
the group consisting of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu
and Zn, M'' is at least one metal selected from the group
consisting of the metals of the groups II A, III A, IV A, V A, VI
A, IB, IIB, IIIB, IVB, VB, VIB and VIIIB, X is selected from the
group consisting of the elements P, Si and S, x is greater than 0,
y is greater than 0, z is greater than or equal to 0, a is greater
than 0 and b is greater than or equal to 0.
Inventors: |
ZINCK; Laurent; (Mothern,
FR) ; PSZOLLA; Christian; (Karlsruhe, DE) ;
RIPP; Christiane; (Pfinztal, DE) ; BORCK; Markus;
(Stuttgart, DE) ; WOLLFARTH; Claudia; (Karlsruhe,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZINCK; Laurent
PSZOLLA; Christian
RIPP; Christiane
BORCK; Markus
WOLLFARTH; Claudia |
Mothern
Karlsruhe
Pfinztal
Stuttgart
Karlsruhe |
|
FR
DE
DE
DE
DE |
|
|
Assignee: |
Fortu Intellectual Property
AG
Sarnen
CH
|
Family ID: |
46801451 |
Appl. No.: |
13/209357 |
Filed: |
August 12, 2011 |
Current U.S.
Class: |
429/163 ; 427/77;
429/211 |
Current CPC
Class: |
Y02E 60/10 20130101;
H01M 10/0525 20130101; H01M 10/0563 20130101; H01M 4/808 20130101;
H01M 2/0275 20130101; H01M 4/5825 20130101; H01M 2/1613 20130101;
H01M 2/08 20130101; H01M 4/485 20130101; H01M 2300/002 20130101;
H01M 2/145 20130101; H01M 2/18 20130101; H01M 4/136 20130101; Y10T
156/10 20150115 |
Class at
Publication: |
429/163 ;
429/211; 427/77 |
International
Class: |
H01M 4/525 20100101
H01M004/525; H01M 4/64 20060101 H01M004/64; B05D 5/12 20060101
B05D005/12; H01M 4/505 20100101 H01M004/505; H01M 4/583 20100101
H01M004/583; H01M 2/02 20060101 H01M002/02; H01M 4/485 20100101
H01M004/485 |
Claims
1. A battery cell, comprising: a housing, a positive electrode, a
negative electrode and an electrolyte, wherein the electrolyte
comprises SO.sub.2 and a conductive salt, wherein the positive
electrode comprises a compound of the formula
Li.sub.xM'.sub.y(XO.sub.4).sub.aF.sub.b (I), which compound is
optionally doped, wherein M' is at least one metal selected from
the group consisting of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu
and Zn, X is selected from the group consisting of the elements P,
Si and S, x is greater than 0, y is greater than 0, a is greater
than 0 and b is greater than or equal to 0, wherein the sum of
positive charges in the compound equals the sum of negative
charges, wherein the positive electrode further comprises a current
collector having a first portion comprising a porous metal which
has a first and second surface and a thickness located there
between and comprises a plurality of pores containing the compound
that extend at least partially through the thickness, wherein at
least some of the pores have void spaces accessible to the
electrolyte and wherein the battery cell is a rechargeable lithium
ion battery cell.
2. A battery cell, comprising: a housing, a positive electrode, a
negative electrode and an electrolyte, wherein the positive
electrode comprises LiFePO.sub.4 which is optionally doped, wherein
the electrolyte comprises SO.sub.2 and a conductive salt, wherein
the positive electrode further comprises a current collector having
a first portion comprising a porous metal which has a first and
second surface and a thickness located there between and comprises
a plurality of pores containing the compound that extend through
the thickness, wherein at least some of the pores have void spaces
accessible to the electrolyte and wherein the battery cell is a
rechargeable lithium ion battery cell.
3. A battery cell, comprising: a housing, a positive electrode, a
negative electrode and an electrolyte, wherein the positive
electrode comprises LiFePO.sub.4 which is optionally doped, the
electrolyte comprises SO.sub.2 and a conductive salt, wherein the
SO.sub.2 is in an amount greater than 40 weight percent of the
weight of the electrolyte and wherein the battery cell is a
rechargeable lithium ion battery cell.
4. A battery cell comprising a housing, a positive electrode, a
negative electrode and an electrolyte, wherein the positive
electrode comprises LiFePO.sub.4 which is optionally doped, wherein
the electrolyte comprises SO.sub.2 and a conductive salt, wherein
organic material is in an amount less than 60 weight percent of the
weight of the electrolyte and wherein the battery cell is a
rechargeable lithium ion battery cell.
5. A battery cell comprising a housing, a positive electrode, a
negative electrode and an electrolyte, wherein the positive
electrode comprises LiFePO.sub.4 which is optionally doped, wherein
the electrolyte comprises SO.sub.2 and a conductive salt, wherein
the electrolyte comprises at least 3 moles SO.sub.2 per mole of
conductive salt, and wherein the battery cell is a rechargeable
lithium ion battery cell.
6. The battery cell according to claim 1, wherein after the first
100 cycles of charging and discharging following formation, the
cell discharge capacity does not decrease by more than 25 percent
over the next 250 cycles, wherein the cell is charged at a current
of 0.5 C until the cell potential reaches 3.6 V at which time the
potential of 3.6 V is held constant until the current reaches 0.1
C, at which time the charging is stopped and after a delay of
approximately 10 minutes, the cell is discharged at a current of
0.5 C and the discharging is stopped when the cell potential
reaches 2.5 V, and wherein after a delay of approximately 60
minutes after the discharging is stopped, (1) and (2) are repeated
for the next cycle, wherein the charge and discharge cycles are
carried out at approximately 20 C and approximately 1 bar (ambient)
pressure.
7. The battery cell of claim 1, wherein the plurality of pores
further contain a compound selected from the group consisting of a
conductive agent, a binding agent, and a lithium halogenide.
8. The battery cell of claim 1, wherein the plurality of pores
extend through the entire thickness.
9. The battery cell of claim 1, wherein the current collector
further comprises a connector portion in conductive contact with
the porous current collector.
10. The battery cell of claim 1, wherein the positive electrode has
a thickness of at least 0.25 mm.
11. The battery of cell of claim 1, wherein the positive electrode
has a thickness of from 0.25 mm to 1.0 mm.
12. The battery cell according claim 1, wherein the positive
electrode comprises a quantity of active material per unit area of
at least 30 mg/cm.sup.2.
13. The battery cell according claim 1, wherein the positive
electrode comprises a quantity of active material per unit area of
from 30 mg/cm.sup.2 to 180 mg/cm.sup.2.
14. The battery cell according to claim 1, wherein the positive
electrode is porous and has a porosity of no more than 50%
15. The battery cell according to claim 1, wherein the negative
electrode has a thickness of at least 0.2 mm.
16. The battery cell according to claim 1, wherein the negative
electrode has a thickness of from 0.2 mm to 0.8 mm.
17. The battery cell according to claim 1, wherein the positive
electrode comprises a binding agent in an amount of no more than 10
wt. % of the active material.
18. The battery cell according to claim 1, wherein the negative
electrode comprises carbon for inserting lithium ions.
19. The battery cell according to claim 1, wherein the negative
electrode comprises a quantity of active material of at least 10
mg/cm.sup.2.
20. The battery cell according to claim 1, wherein the negative
electrode comprises a quantity of active material per unit area of
from 10 mg/cm.sup.2 to 100 mg/cm.sup.2.
21. The battery cell according to claim 1, wherein the negative
electrode is porous and its porosity is no more than 50%.
22. The battery cell according to claim 1, wherein the negative
electrode comprises a porous metal portion and binding agent
contained therein and the binding agent is in an amount of no more
than 5 wt. % of the weight of the porous metal portion of the
negative electrode.
23. The battery cell according to claim 1, wherein the electrolyte
comprises at least 3 moles SO.sub.2 per mole of conductive
salt.
24. The battery cell according to claim 1, wherein the electrolyte
comprises from 3 to 220 moles SO.sub.2 per mole of conductive
salt.
25. The battery cell according to claim 1, wherein the conductive
salt comprises lithium tetrachloroaluminate.
26. The battery cell according to claim 1, wherein the positive
electrode has a current carrying capacity of at least 10
mA/cm.sup.2.
27. The battery cell according to claim 1, wherein the positive
electrode has an ampacity per unit area of from 10 mA/cm.sup.2 to
150 mA/cm.sup.2
28. The battery cell according to claim 1, wherein lithium chloride
is mixed with active metal of the positive electrode.
29. The battery cell according to claim 1, wherein the positive
and/or negative electrode is treated to reduce covering layers by
means of applying a surface coating to the electrode.
30. A method for producing a positive electrode for a lithium ion
rechargeable battery, comprising: providing a paste mass comprising
LiFePO.sub.4, optionally with admixture of a binding agent or a
conductivity-improving material; homogeneously incorporating the
paste mass into a three-dimensional porous metal current collector;
and pressing the three-dimensional metal current collector
comprising the paste mass in such a manner that its thickness is
reduced.
31. An electrode produced according to the method of claim 23.
32. The battery cell of claim 1, wherein the electrolyte comprised
therein will not ignite or combust when a battery comprising the
cell is placed above a Bunsen burner and contacted with the tip of
a blue flame of the Bunsen burner for at least 10 minutes.
33. A motor vehicle power supply, comprising the battery cell of
claim 1.
34. An energy storage system, comprising the battery cell of claim
1.
Description
FIELD
[0001] The field relates to rechargeable lithium ion battery cells
and treated electrodes for rechargeable battery cells and methods
thereof.
BACKGROUND
[0002] It is well known that conventional rechargeable lithium ion
battery cells have a history of safety problems. These safety
problems are caused, in part, by the organic solvent electrolyte in
such battery cells, which is flammable. Because of this danger,
conventional rechargeable lithium ion battery cells contain
components designed to activate in the event of cell failure in
order to prevent combustion of the organic solvent electrolyte.
However, these components lead to, for example, increased
manufacturing costs and increase the volume and weight of the
cell.
SUMMARY
[0003] In an embodiment, the positive electrode comprises an active
material, a current collector and optionally a binder and/or
conductive agent (to improve conductivity). In a further
embodiment, the negative electrode comprises an active material, a
current collector and optionally a binder and/or conductive
material. In a further embodiment, the positive electrode and/or
negative electrode are treated to reduce capacity loss due to
formation of stable covering layers on the positive and negative
electrodes (for example, SEI layers).
[0004] In an embodiment is provided a battery cell, comprising: a
housing, a positive electrode, a negative electrode and an
electrolyte, wherein the electrolyte comprises SO.sub.2 and a
conductive salt, wherein the positive electrode comprises a
compound of the formula Li.sub.xM'.sub.y(XO.sub.4).sub.aF.sub.b (I)
as defined herein, wherein the positive electrode further comprises
a current collector having a first portion comprising a porous
metal which has a first and second surface and a thickness located
there between and comprises a plurality of pores containing the
compound that extend at least partially through the thickness,
wherein at least some of the pores have void spaces accessible to
the electrolyte and wherein the battery cell is a rechargeable
lithium ion battery cell.
[0005] In a further embodiment is provided a battery cell,
comprising: a housing, a positive electrode, a negative electrode
and an electrolyte, wherein the positive electrode comprises
LiFePO.sub.4 which is optionally doped, wherein the electrolyte
comprises SO.sub.2 and a conductive salt, wherein the positive
electrode further comprises a current collector having a first
portion comprising a porous metal which has a first and second
surface and a thickness located there between and comprises a
plurality of pores containing the compound that extend through the
thickness, wherein at least some of the pores have void spaces
accessible to the electrolyte and wherein the battery cell is a
rechargeable lithium ion battery cell.
[0006] In a further embodiment is provided a battery cell,
comprising, a housing, a positive electrode, a negative electrode
and an electrolyte, wherein the positive electrode comprises
LiFePO.sub.4 which is optionally doped, the electrolyte comprises
SO.sub.2 and a conductive salt, wherein the SO.sub.2 is in an
amount greater than 40 weight percent of the weight of the
electrolyte and wherein the battery cell is a rechargeable lithium
ion battery cell.
[0007] In a further embodiment is provided a battery cell
comprising a housing, a positive electrode, a negative electrode
and an electrolyte, wherein the positive electrode comprises
LiFePO.sub.4 which is optionally doped, wherein the electrolyte
comprises SO.sub.2 and a conductive salt, wherein organic material
is in an amount less than 60 weight percent of the weight of the
electrolyte and wherein the battery cell is a rechargeable lithium
ion battery cell.
[0008] In a further embodiment is provided a battery cell
comprising a housing, a positive electrode, a negative electrode
and an electrolyte, wherein the positive electrode comprises
LiFePO.sub.4 which is optionally doped, wherein the electrolyte
comprises SO.sub.2 and a conductive salt, wherein the electrolyte
comprises at least 3 moles SO.sub.2 per mole of conductive salt,
and wherein the battery cell is a rechargeable lithium ion battery
cell.
[0009] In an embodiment, the measurements described herein are at
20 degrees C. and 1 bar.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a cross-sectional view of a battery cell
embodiment.
[0011] FIG. 2 shows a cross-sectional view of a metal foam
embodiment.
[0012] FIG. 3 shows a cross-sectional view of a portion of a
positive electrode embodiment.
[0013] FIG. 4 shows a view of a porous metal current collector
embodiment.
[0014] FIG. 5 shows a view of an electrode embodiment and a
schematic representation of the porous metal current collector
portion of the electrode filled with active material.
[0015] FIG. 6 shows a view of an embodiment showing a positive
electrode contained in a pouch faced on each side by a negative
electrode.
[0016] FIG. 7 shows an embodiment of a layer for covering a
plurality of electrodes.
[0017] FIG. 8 shows an embodiment of a prismatic housing containing
a plurality of electrodes,
[0018] FIG. 9 shows an embodiment of a prismatic housing containing
a plurality of electrodes and a top cover thereto.
[0019] FIG. 10 shows an embodiment of the top cover of a prismatic
housing.
[0020] FIG. 11 shows the dependence of the discharge capacity at
different discharge C-rates on the number of cycles for an
experiment performed with a positive electrode.
[0021] FIG. 12 shows the dependence of the discharge capacity on
the discharge rate for an experiment performed with a positive
electrode in comparison with published results.
[0022] FIG. 13 shows the dependence of the electrical resistance of
an electrode at different discharge C-rates on the number of cycles
for an experiment performed with a positive electrode.
[0023] FIG. 14 shows the dependence of the capacity on the number
of cycles for an experiment performed with two different positive
electrodes.
[0024] FIG. 15 shows the dependence of the capacity on the number
of cycles for a further experiment performed with two different
positive electrodes.
[0025] FIG. 16 shows the dependence of the discharge capacity on
the number of cycles for an experiment performed with two different
positive electrodes.
[0026] FIG. 17 shows the dependence of the capacity on the number
of cycles for a long-duration experiment.
[0027] FIG. 18 shows the dependence of the electrical voltage on
the charging capacity for three differently treated negative
electrodes.
[0028] FIG. 19 shows the percent of discharge capacity versus cycle
number for different molar ratios of SO.sub.2 to conductive salt
for LiCoO.sub.2 active material.
[0029] FIG. 20 shows the percent of discharge capacity versus cycle
number for different molar ratios of SO.sub.2 to conductive salt
for LiFePO.sub.4 active material.
DETAILED DESCRIPTION
[0030] As described below, embodiments of the described
rechargeable lithium ion battery cell, comprise a positive
electrode, a negative electrode, a housing and an electrolyte,
where the electrolyte comprises SO.sub.2 and a conductive salt and
a housing.
Positive Electrode
[0031] Positive Electrode Active Material and Other Compounds
[0032] In an embodiment, the positive electrode comprises an active
material compound of the formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I). In an
embodiment M' is at least one metal selected from the group
consisting of the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn. In
a further embodiment M'' is at least one metal selected from the
group consisting of the metals of the groups II A, III A, IV A, V
A, VI A, IB, IIB, IIIB, IVB, VB, VIB and VIIIB, and such metals
are, for example, doping metals. In an embodiment X is selected
from the group consisting of the elements P, Si and S. In a further
embodiment x is greater than 0, y is greater than 0, z is greater
than or equal to 0, a is greater than 0 and b is greater than or
equal to 0.
[0033] In a further embodiment, the active material comprises a
phosphate, and in this case X is thus phosphorus. In a further
embodiment, M' is iron. In a further embodiment, b is equal to 0
and in this case, the active material thus does not contain any
fluorine.
[0034] In a further embodiment, the compound of formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I) is
LiFeM''.sub.zPO.sub.4. In a further embodiment, the compound of
formula Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula
I) is LiFePO.sub.4.
[0035] The term "at least one metal" used in
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I) means
that M' and M'' each may be two or more of the respectively defined
metals. Accordingly, the recitations y and z refer to the totality
of metals that are recited above, respectively, by M' and M''. As
an example, where M' is two of the defined metals, in the case, for
example, where the compound of the formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I) is
Li.sub.1[Fe.sub.mMn.sub.1-m].sub.1PO.sub.4, then
0.0.ltoreq.m.ltoreq.1.0, x, y and a are 1 and b and z are 0. In
another aspect, where the compound of the formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I) is,
for example, a doped LiFePO.sub.4 compound, then the variables in
Li.sub.1[Fe.sub.1-zM''.sub.z].sub.1PO.sub.4, are:
0.0.ltoreq.z.ltoreq.1.0, x and a are 1, y is 1-z and b is 0.
[0036] In a further embodiment, where M'' is a doping metal or
metals, as mentioned above, such doping metals are, for example, in
an amount (each doping metal independently or the two or more
doping metals in combination) less than or equal to 10 mole percent
of the total number of moles of M'.sub.y in the compound of
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I).
[0037] In a another embodiment, the compound of formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I) is
Li.sub.xM'.sub.y(XO.sub.4).sub.aF.sub.b, and the compound is
optionally doped. In a further embodiment, in a doped compound of
the formula Li.sub.xM'.sub.y(XO.sub.4).sub.aF.sub.b, the doped
metal or metals are, for example, in an amount, (each doping metal
independently or the two or more doping metals in combination) less
than or equal to 10 mole percent of the total number of moles of
M'.sub.y in the compound.
[0038] In a further embodiment, the doping metals are, for example,
selected from the group consisting of aluminum, magnesium, niobium,
zirconium and ions thereof.
[0039] In the compound of formula
Li.sub.xM'.sub.yM''.sub.z(XO.sub.4).sub.aF.sub.b (Formula I), the
condition of charge neutrality is applied. That is, the sum of
positive charges of Li, M' and (when contained in the compound) M''
equal the sum of the negative charges of the XO.sub.4 and (when
contained in the compound) F.
[0040] Examples of commercially available positive electrode active
materials are listed in Table 1 below:
TABLE-US-00001 TABLE 1 Company Name Compound Product Name Phostech
Lithium Inc. LiFePO.sub.4 Grade P1 Phostech Lithium Inc.
LiFePO.sub.4 Grade P2 Alees (Advanced Lithium LiFePO.sub.4 LFP-NCO
M121 Electrochemistry Co., Ltd.) Alees (Advanced Lithium
LiFePO.sub.4 LFP-NCO M12 Electrochemistry Co., Ltd.) Formosa Energy
& Material LiFe.sub.xM.sub.(1-x)P.sub.yO.sub.z SFCM30050
Technology Co., Ltd. Prayon S.A. LiFeBPO.sub.4 Lithium Boron Iron
Phosphate
[0041] In a further embodiment, the active material is in the form
of particles and the mean particle size of such particles is at
least 0.1 .mu.m, at least 0.2 .mu.m, at least 0.5 .mu.m, at least 1
.mu.m or at 2 .mu.m. In a further embodiment, the mean particle
size is from 0.1 .mu.m to 2 .mu.m, 0.1 .mu.m to 3 .mu.m, or 0.1
.mu.m to 4 .mu.m or from 0.2 .mu.m to 2 .mu.m, 0.2 .mu.m to 3
.mu.m, or 0.2 .mu.m to 4 .mu.m.
[0042] In a further embodiment, active material particles are
coated with, for example, with carbon or carbon containing
materials, to, for example, increase conductivity.
[0043] In a further embodiment, the positive electrode comprises a
conductive agent compound, for example, carbon black or other
carbon containing materials, to improve the conductivity of the
active material. For example, in an embodiment, the active material
is admixed with such conductive agents.
[0044] In a further embodiment, the positive electrode optionally
comprises a binding agent compound, for example the active material
is admixed with a binding agent. In an embodiment, the binding
agent is selected from the group consisting of: a fluorinated
binding agent, THV (terpolymer of tetrafluoroethylene,
hexafluoropropylene and vinylidene fluoride) and PVDF
(polyvinylidene fluoride).
[0045] In a further embodiment, to increase, for example, cell
cycling stability, the positive electrode optionally comprises a
lithium halogenide compound. For example, in an embodiment, the
active material is admixed with a lithium halogenide. In an
embodiment, the lithium halogenide is lithium chloride.
[0046] In a further embodiment, in addition to the above described
active material, the positive electrode optionally comprises a
compound selected from the group consisting of a conductive agent,
a binding agent, and a lithium halogenide, as described above, for
example, in admixture with the active material.
[0047] Positive Electrode Porous Metal Current Collector
[0048] In an embodiment, the positive electrode contains a current
collector which in whole or in part comprises a porous metal. In an
embodiment, the porous metal 20 has a first and second surface (for
example, a front and a back surface as shown in FIG. 4) and a
thickness d between the first and second surface.
[0049] In an embodiment, the porous metal comprises a plurality of
pores P that are defined by the porous metal structure 13. As shown
in FIG. 4, in an embodiment, the pores P extend through the entire
thickness and surfaces of the porous metal 20.
[0050] In a further embodiment, the porous metal 20 is a
reticulated metal with the reticulated metal structure defining the
pores. In a further embodiment, the porous metal 20 is, for
example, a metal foam, metal fleece, metal mesh or metal fabric. In
a further embodiment, the metal is, for example, nickel or copper
metal. An electron microscope image of a porous nickel metal foam
embodiment is shown in FIG. 2 and in the insets shown in FIG.
4.
[0051] In an embodiment, the pores of the porous metal extend at
least partially through the porous metal thickness d. In a further
embodiment, the pores of the porous metal extend from at least one
surface of the porous metal through at least 50 percent, at least
60 percent, at least 70 percent, at least 80 percent or at least 90
percent of the porous metal thickness d. In a further embodiment,
the porous metal comprises at least 50 percent, at least 60
percent, at least 70 percent, at least 80 percent or at least 90
percent of the positive electrode thickness d.
[0052] In a further embodiment, the porous metal comprises at least
50 percent, at least 60 percent, at least 70 percent, at least 80
percent or at least 90 percent of the current collector exterior
surfaces. In a further embodiment, the porous metal comprises at
least 50 percent, at least 60 percent, at least 70 percent, at
least 80 percent or at least 90 percent of the positive electrode
exterior surfaces.
[0053] Exemplifications of commercially available porous metal foam
embodiments of are listed below in Table 2.
TABLE-US-00002 TABLE 2 Density Company Name Material (g/m.sup.2)
Pore size (.mu.m) Thickness (mm) Storck nickel 380.00 -- 1.30
Nitech nickel 350.00 -- 1.30 Inco nickel 380.00 560.00 1.70 Inco
nickel 380.00 580.00 1.70 Inco nickel 480.00 580.00 1.70 Inco
nickel 880.00 -- 0.36 Inco nickel 1100.00 -- 0.36 Alantum copper
430.00 580.00 1.70 Alantum copper 480.00 580.00 1.70 Alantum copper
350.00 580.00 1.70 Changsha Lyrun copper 480.00 95 ppi 1.70
Changsha Lyrun nickel 480.00 95 ppi 1.70 Changsha Lyrun copper
400.00 120 ppi 1.70 Changsha Lyrun nickel 480.00 120 ppi 1.70
[0054] Positive Electrode Porous Metal Current Collector Containing
Active Material And Other Compounds
[0055] In a further embodiment, the pores P of the porous metal 20
contain active material and optionally the other compounds
discussed above. FIG. 3 shows an electron microscope image of the
porous metal current collector portion of a positive electrode,
having a thickness d and containing active material 15 in pores
defined by the porous metal structure 13. In FIG. 5, in the insets,
are schematic representations of the pores of the porous metal
containing active material and optionally other compounds as
described above 21. The schematic insets of FIG. 5 also show void
spaces 22 that are defined by the active material contained in the
pores and are accessible to the cell electrolyte. That is, in an
embodiment, the active material and optionally the other compounds
as described above fill pores P by, for example, adhering to the
porous metal structure 13 that defines the pores; however, the
active material and optionally the other compounds as described
above do not completely occlude the pores P and instead partially
occlude at least some of the pores P thereby defining void spaces
22 that are accessible to the cell electrolyte.
[0056] As noted above, the void spaces 22 shown in FIG. 5 are only
a schematic representation and do not correspond to the actual size
or the precise configuration of embodiments of the void spaces. For
example, in an embodiment, as set forth herein, the average pore
size is 580 micrometers and the average pore size of void spaces
contained in a porous metal filled with active material is from 50
to 80 nanometers.
[0057] The result of this embodiment is that, due to the pores in
the above-described current collector, the average distance of the
active material to the current collector metal is decreased as
compared to active material adhered to a planar current collector
metal foil.
[0058] In an embodiment, the active material and optionally the
other compounds discussed above, are applied (e.g., homogenously)
to the porous metal and excess compounds are removed from the
surface(s) of the porous metal. The porous metal containing the
compounds is then pressed. In an embodiment, the thickness of the
filled porous metal (e.g., after pressing) is no more than 50
percent or no more than 40 percent of the initial thickness of the
porous metal starting material.
[0059] In an embodiment, the active material and optionally the
other compounds are in an admixture. In a further embodiment,
conductive agent is in an amount less than ten weight percent, less
than seven weight percent, less than five weight percent or less
than two weight percent of the weight of the porous metal portion
of the electrode. In a further embodiment, binding agent is in an
amount less than five weight percent or less than two weight
percent of the weight of the weight of the porous metal portion of
the electrode.
[0060] Herein, the term weight percent (wt. %) as applied to a
component of a composition refers to the weight of that component
divided by the total weight of the composition, expressed as a
percentage. For example, as applied to the above paragraph, if a
solid composition is a mixture of W grams active material, X grams
binding agent and Y grams conductive agent in Z grams of nickel
foam, then the wt. % of binding agent is given by:
X W + X + Y + Z .times. 100. ##EQU00001##
[0061] Thus, as used herein, the description that "the binding
agent is in an amount less than ten weight percent of the weight of
the porous metal portion of the electrode" means that if the total
weight of the porous metal portion of the electrode is 100 g, then
the total weight of the binding agent contained therein is less
than 10 g.
[0062] As an additional example, in the context of a liquid
composition, for example, an electrolyte comprising SO.sub.2, a
conductive salt(s), and an organic co-solvent, the description that
the organic material is in an amount less than 60 weight percent of
the weight of the electrolyte means that if the total weight of the
electrolyte (that is the total weight in grams of the SO.sub.2,
conductive salt and organic solvent) is 100 g then the weight of
the organic co-solvent is less then 60 g.
[0063] Moreover, it will be understood that when a liquid
electroyte composition containing SO.sub.2 is used in a sealed
battery cell housing, the SO.sub.2 may be in an equilibrium between
the liquid and gas phase and the relative amounts of gas and liquid
phase SO.sub.2 may vary depending on the ambient conditions. As
used herein the weight percent of a component of the liquid
electrolyte composition is calculated taking into consideration the
total of the liquid and gas phase SO.sub.2. Thus, the weight
percent may be determined using either (i) the weights (typically
in grams) of SO.sub.2, conductive salt and organic solvent that
were admixed to create the electrolyte or (ii) may be calculated
based on an analysis of the electrolyte components in the housing,
for example, by opening the battery cell housing in an atmosphere
of inert gas under pressure and measuring the molecular content of
the gas and liquid contained therein. It is further understood that
the term "electrolyte" herein refers to an electrolyte admixture,
with the meaning that, where some of the SO.sub.2 is in a gas form
and therefore is not functioning as an electrolyte (in that, it is
not involved in conductivity of lithium ions), the SO.sub.2 is
still to be considered as part of the electrolyte admixture and
therefore the amount of SO.sub.2 in the "electrolyte" as applied to
a sealed battery cell refers to the total amount of SO.sub.2
therein whether in liquid or gaseous form.
[0064] In a further embodiment, the porous metal current collector
comprising (for example, filled with) the active material and
optionally the other compounds discussed above, has the following
ranges of porosity, loading, thickness and pore size. In a further
embodiment, in the below ranges, the porosity, thickness and pore
sizes are based on (but not limited to) a porous metal current
collector comprising active material (LiFePO.sub.4), conductive
agent (carbon black) and binding agent (THV) and the loading is
based on (but not limited to) the mass of active material (mg)
(LiFePO.sub.4) per unit area (cm.sup.2) of the porous metal current
collector containing active material, conductive agent and binding
agent. In a further embodiment, the porosity listed in the ranges
below, is measured, for example, by mercury intrusion
porosimetry.
[0065] The following are with respect, for example, to high energy
cell embodiments. With regard to porosity, in embodiments, the
porosity is from 25-30 percent, 20 to 30 percent or from 20 to 50
percent. With regard to loading, in embodiments, loading is from
110 to 115 mg/cm.sup.2, 90 to 180 mg/cm.sup.2 and 20 to 180
mg/cm.sup.2. With regard to thickness, in embodiments, thickness is
from 575 to 585 .mu.m, 450 to 800 .mu.m and 250 to 800 .mu.m.
[0066] The following are with respect, for example, to high power
cell embodiments. With regard to porosity, in embodiments, the
porosity is from 33 to 37 percent, 30 to 50 percent and 20 to 50
percent. With regard to loading, in embodiments, loading is from 70
to 75 mg/cm.sup.2, 20 to 90 mg/cm.sup.2 and 20 to 180 mg/cm.sup.2.
With regard to thickness, in embodiments, thickness is from 445 to
455 .mu.m, 250 to 500 .mu.m and 250 to 600 .mu.m.
[0067] In a further embodiment, the average pore size of the pores
containing the compounds is from 50-80 nm.
[0068] In a further embodiment, the porosity is no more than 50
percent, no more than 50 percent, 45 percent, 40 percent, 35
percent, 30 percent, 25 percent or 20 percent. In a further
embodiment, thickness is at least 0.25 mm, at least 0.3 mm, at
least 0.4 mm, at least 0.5 mm or at least 0.6 mm. In a further
embodiment, loading is at least 30 mg/cm.sup.2, at least 40
mg/cm.sup.2, at least 60 mg/cm.sup.2, at least 80 mg/cm.sup.2, at
least 100 mg/cm.sup.2, at least 120 mg/cm.sup.2 or at least 140
mg/cm.sup.2.
[0069] In a further embodiment, thickness is from 0.20 mm to 1.0
mm.
[0070] In a further embodiment, the current collector comprises a
second portion, namely a connector which is electrically
conductively connected to the porous metal. In this embodiment, the
connector and the porous metal comprising the active material, and
optionally the other compounds described above, comprise the
electrode 35 as shown in FIG. 5.
[0071] In a further embodiment, the connector comprises a metal
foil folded over an edge of the porous metal. In a further
embodiment, the connector comprises a metal foil band folded over
the top edge of the porous metal. In a further embodiment, a metal
foil tab is attached to the band. In a further embodiment 23, a
metal foil band is folded over the top edge of the porous metal, a
metal foil tab is attached to the band and one or more wires are
attached to the tab. In a further embodiment, the foil and wire
comprise nickel metal.
[0072] Negative Electrode Active Material and Other Compounds
[0073] In an embodiment, the negative electrode comprises an active
material graphite compound or another form of carbon compound that
is suitable for intercalating lithium ions as is understood by the
skilled artisan.
[0074] A listing of embodiments of commercially available graphite
active material is shown below in Table 3.
TABLE-US-00003 TABLE 3 Company Name Product Name Timcal SFG6 Timcal
SFG44 Timcal KS4 Timcal SLP50 Timcal SLP30 Timcal E-SLG5 - 07/04
Timcal E-SLX 50 - 032 Timcal SFG150 Timcal KS150 Carbonix TX25
Carbonix TX20L Kropfmuhl Graphit SGB 25 L/99.9 Kropfmuhl Graphit
SGB 20 L/99.9 Kropfmuhl Graphit SGB 10 L/99.9 Aschland Sudchemie
MCMB 6-28 Aschland Sudchemie MCMB 10-28 Aschland Sudchemie MCMB
25-28 LICO LPG320--potato Graphite
[0075] In a further embodiment, the negative electrode optionally
comprises a binding agent compound, for example the active material
is admixed with a binding agent, with the binding agent being
selected from the group of binding agents described above with
respect to the positive electrode. In a further embodiment, the
binding agent is in an amount no more than five weight percent,
three weight percent or one weight percent of the weight of the
porous metal portion of the electrode.
[0076] Negative Electrode Porous Metal Current Collector
[0077] In an embodiment, the negative electrode contains a current
collector which in whole or in part comprises a porous metal. In an
embodiment, the porous metal current collector portion of the
negative electrode is as described above with respect to the
positive electrode.
[0078] Negative Electrode Porous Metal Current Collector Containing
Active Material And Optionally Binder
[0079] In an embodiment, the porous metal current collector
containing active material and optionally binder (for example, in
admixture) is as described above with respect to the positive
electrode porous metal current collector containing active material
and optionally other compounds.
[0080] In a further embodiment, the porous metal current collector
comprising (for example, filled with) active material and
optionally binding agent has the following ranges of porosity,
loading, thickness and pore size. In a further embodiment, in the
below ranges, the porosity, thickness and pore sizes are based on
(but not limited to) a porous metal current collector comprising
graphite active material and not containing a binding agent or a
conductive agent and the loading is based on (but not limited to)
the mass of graphite active material (mg) per unit area (cm.sup.2)
of the porous metal current collector containing the active
material. In a further embodiment, the porosity listed in the
ranges below, is measured, for example, by mercury intrusion
porosimetry.
[0081] The following are with respect, for example, to high energy
cell embodiments. With regard to porosity, in embodiments, the
porosity is from 30-35 percent, 30-40 percent or from 30-50
percent. With regard to loading, in embodiments, loading is from
45-50 mg/cm.sup.2, 25-55 mg/cm.sup.2 and 10-100 mg/cm.sup.2. With
regard to thickness, in embodiments, thickness is from 390-410
.mu.m, 300-500 .mu.m and 200-800 .mu.m.
[0082] The following are with respect, for example, to high power
cell embodiments. With regard to porosity, in embodiments, the
porosity is from 43-47 percent, 40-50 percent and 30-50 percent.
With regard to loading, in embodiments, loading is from 25-30
mg/cm.sup.2, 15-35 mg/cm.sup.2 and 10-100 mg/cm.sup.2. With regard
to thickness, in embodiments, thickness is from 315-325 .mu.m,
200-400 .mu.m and 200-600 .mu.m.
[0083] In a further embodiment, the average pore size of the pores
containing the active material and optionally the binder is from
50-90 nm.
[0084] In a further embodiment, the porosity is no more than 50
percent, 45 percent, 40 percent, 35 percent or 30 percent. In a
further embodiment, thickness is at least 0.2 mm, at least 0.3 mm,
at least 0.4 mm, at least 0.5 mm or at least 0.6 mm. In a further
embodiment, loading is at least 10 mg/cm.sup.2, at least 20
mg/cm.sup.2, at least 40 mg/cm.sup.2, at least 60 mg/cm.sup.2, at
least 80 mg/cm.sup.2 or at least 100 mg/cm.sup.2.
[0085] In a further embodiment, thickness is from 0.20 mm to 1.0
mm.
[0086] In a further embodiment, the current collector comprises a
second portion, namely a connector which is electrically
conductively connected to the porous metal. In this embodiment, the
connector and the porous metal comprising the active material, and
optionally the other compounds described above, comprise the
electrode 35 as shown in FIG. 5.
[0087] In a further embodiment, the connector comprises a metal
foil folded over an edge of the porous metal. In a further
embodiment, the connector comprises a metal foil band folded over
the top edge of the porous metal. In a further embodiment, a metal
foil tab is attached to the band. In a further embodiment 23, a
metal foil band is folded over the top edge of the porous metal, a
metal foil tab is attached to the band and one or more wires are
attached to the tab. In a further embodiment, the foil and wire
comprise nickel metal.
Electrolyte
[0088] In an embodiment, the electrolyte comprises SO.sub.2 and a
conductive salt and in a further embodiment is non-aqueous.
[0089] Regarding the conductive salt, in an embodiment, the
conductive salt is selected from the group consisting of
aluminates, halogenides, oxalates, borates, phosphates, arsenates
and gallates of an alkali metal or alkaline earth metal. In a
further embodiment, the conductive salt is lithium
tetrahalogenoaluminate. In yet a further embodiment, the conductive
salt is lithium tetrachloroaluminate.
[0090] In a further embodiment, SO.sub.2 is in an amount greater
than 30 weight percent, greater than 40 weight percent, greater
than 50 weight percent, greater than 60 weight percent, greater
than 70 weight percent, greater than 80 weight percent, greater
than 85 weight percent, or greater than 90 weight percent of the
weight of the electrolyte.
[0091] In a further embodiment, in addition to SO.sub.2, the
electrolyte may comprise one or more additional inorganic solvents,
for example, sulfuryl chloride or thionlyl chloride.
[0092] In a further embodiment, the electrolyte may contain organic
material, for example, one or more organic co-solvents. In such an
embodiment, the organic material is in an amount less than 50
weight percent, less than 40 weight percent, less than 30 weight
percent, less than 20 weight percent, less than 15 weight percent,
less than 10 weight percent, less than 5 weight percent, or less
than 1 weight percent of the weight of the electrolyte. In a
further embodiment, the electrolyte is essentially free of organic
material; that is, the electrolyte contains organic material as an
impurity only (for example an impurity resulting from carbon
coating on the positive electrode active material or from other
carbon material in the electrodes, e.g., carbon black in the
positive electrode or graphite in the negative electrode) not an
additive. In a further embodiment, the electrolyte contains no more
than 500 parts per million organic material. In a further
embodiment, the organic material contained in the electrolyte has a
flash point below 200.degree. C., 150.degree. C., 100.degree. C.,
50.degree. C., 25.degree. C. or 10.degree. C. In a further
embodiment, where the electrolyte contains (or is admixed with) two
or more organic materials, the combined organic materials have an
average (calculated, for example, by weight percent) flash point
below 200.degree. C., 150.degree. C., 100.degree. C., 50.degree.
C., 25.degree. C. or 10.degree. C.
[0093] In a further embodiment, nitriles (for example, mononitriles
or dinitriles) are in an amount less than 50 weight percent, less
than 40 weight percent, less than 30 weight percent, less than 20
weight percent, less than 15 weight percent, less than 10 weight
percent, less than 5 weight percent, or less than 1 weight percent
of the weight of the electrolyte.
[0094] In a further embodiment, conductive salt is in an amount
less than 70 weight percent, less than 60 weight percent, less than
50 weight percent, less than 40 weight percent, less than 30 weight
percent, less than 20 weight percent or less than 10 weight percent
of the weight of the electrolyte.
[0095] In a further embodiment, SO.sub.2 plus conductive salt is in
an amount greater than 50 weight percent, greater than 60 weight
percent, greater than 70 weight percent, greater than 80 weight
percent, greater than 85 weight percent, greater than 90 weight
percent, greater than 95 weight percent or greater than 99 weight
percent of the weight of the electrolyte. In a further embodiment,
the electrolyte consists essentially of SO.sub.2 and conductive
salt. That is, other than SO.sub.2 and conductive salt, the
electrolyte contains less than one weight percent of other
materials.
[0096] It is understood that included in this description is the
combination of any two or more of the above weight percentages.
Moreover, this description in the previous sentence does not
detract from the fact that it is to be understood that embodiments
herein also include any of the embodiments mentioned herein
combined with any other one or more embodiments herein
mentioned.
[0097] In an embodiment, the electrolyte comprises at least 2.0
moles SO.sub.2 per mole of conductive salt. In a further
embodiment, the electrolyte comprises at least 2, 2.5, 3, 3.5, 4,
4.5, 5, 5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12,
12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5,
19, 19.5, or 20 moles SO.sub.2 per mole of conductive salt.
[0098] In a further embodiment, the electrolyte comprises from 2,
2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, or 8 moles SO.sub.2
per mole of conductive salt to 20, 25, 30, 35, 50, 100, 150, 200,
or 220 moles SO.sub.2 per mole of conductive salt.
[0099] In a further aspect, the maximum ratio of the moles of
SO.sub.2 per mole of conductive salt is set by (1) the desired
safety parameters of the cell or (2) the desired levels of
electrolyte ionic conductivity of the cell.
[0100] In a further embodiment, the electrolyte is synthesized
according to the process set forth in either of Tables 4 and 5
below. The processes set forth in Tables 4 and 5 are carried out in
an inert gas (argon), at room temperature and unless otherwise
stated at ambient pressure (1 bar).
TABLE-US-00004 TABLE 4 Drying Drying of lithium chloride 3
days/120.degree. C./vacuum Drying of aluminum particles 2
days/450.degree. C./vacuum Mixing LiCl 434 g (10.3 mole) (42
g/mole) AlCl.sub.3 1300 g (9.7 mole) (134 g/mole) Al 100 g (3.4
mole) (29 g/mole) Mix well 1 mole AlCl.sub.3 to 1.06 mole LiCl to
0.35 mole Al in glass flask with an opening to permit the escape of
gas. Melting 250.degree. C. for 2 hours 350.degree. C. for 2 hours
500.degree. C. for 2 hours After 6 hours, the opening in the flask
is closed. 500.degree. C. for 3 days Filtering Cooling to
250.degree. C. Filter through a glass fiber cloth. Introduction to
The next day the melt is cooled to room temperature. SO.sub.2 gas
The flask with the melt is evacuated and SO.sub.2 is introduced up
to a desired amount, to obtain a desired mole ratio of SO.sub.2 per
mole of LiAlCl.sub.4, from a container containing the SO.sub.2
under pressure. The flask is cooled while gas is introduced. The
salt melt is dissolved in the SO.sub.2 and the liquid electrolyte
is obtained.
TABLE-US-00005 TABLE 5 Drying Drying of lithium chloride at
750.degree. C. Mixing LiCl 434 g (10.3 mole) (42 g/mole) AlCl.sub.3
1300 g (9.7 mole) (134 g/mole) Mix 1 mole AlCl.sub.3 to 1.06 mole
LiCl in a glass flask with an opening to permit the introduction of
SO.sub.2. Introduction of The flask is evacuated. Next, the desired
amount of SO.sub.2 gas SO.sub.2 is introduced with an over pressure
of 1.5 bar (by "over pressure" it is meant 1.5 bar over the ambient
1 bar argon pressure), while stirring the salt mixture. When the
salt begins to dissolve in the SO.sub.2, the pressure of the
SO.sub.2 is reduced to an over pressure of 0.5 bar in order to slow
the process to permit obtaining a liquid electrolyte having a
desired molar ratio of SO.sub.2 to LiAlCl.sub.4 salt.
[0101] Other embodiments for producing the electrolyte described
herein are found, for example, in Foster, et al., "New Highly
Conductive Inorganic Electrolytes--The Liquid S02 Solvates of the
Alkali and Alkaline Earth Metal Tetrachloroaluminates," J.
Electrochem. Soc., 135: 2682-2686 (1988) and Koslowski,
"Rontgenographische und schwingungsspektroskopische Untersuchungen
an Solvaten des Typs MAIC14/SO2 (M=Li, Na) und deren
Wechselwirkungen mit Aromaten," Doctoral Thesis, University of
Hannover/Germany (1980).
Properties of the Cell and its Components
[0102] In an embodiment, the electrolyte has, at room temperature,
an ionic conductivity of 70 millisiemens/cm.
[0103] In a further embodiment, the cells described herein have
thick electrodes (ranges of thickness are set forth above) due to,
inter alia, (without being bound by this theory) the ionic
conductivity of the electrolytes described herein. The electrode
thickness described herein is also provided due to, inter alia,
(without being bound by this theory) the porous metal current
collector portions described herein which permits access of the
electrolyte and active material, for example, throughout the
interior of the porous current collector structure. Such thick
electrodes permit, for example, decreased manufacturing costs (that
is, less electrodes may be used per cell).
[0104] Also provided, inter alia, by embodiments of the
electrolytes described herein is cell cycle stability, for example,
a stable internal resistance of embodiments of the battery cells
described herein over multiple cycles. Without being bound by this
theory, it is believed that this stability results, inter alia,
from the formation of stable electrode covering layers resulting
from the chemical interaction of the electrolytes and electrodes
described herein.
[0105] Moreover, in an embodiment, the battery cells described
herein, have cell cycle stability (for example, the cell discharge
capacity is substantially constant) over numerous cycles.
[0106] In an embodiment, after the first 100 cycles following
formation, the cell discharge capacity does not decrease by more
than 25% over the next 250 cycle increment. In a further
embodiment, after 100 cycles following formation, the discharge
capacity will not decrease by more than 25%, 20%, 15%, 10%, 5%,
1.5% or 1% over the next 250 cycle increment.
[0107] In a further embodiment, the percent loss of discharge
capacity is calculated by comparing the discharge capacity at a
given number of cycles (for example, at 100 cycles following
formation as described above) to the discharge capacity after a
given number of additional cycles (for example, an increment of 250
cycles as described above). For example, for the first increment in
the example of the foregoing sentence, if the discharge capacity at
100 cycles is 100 mAh and is 90 mAh at 350 cycles, then the percent
loss of discharge capacity would by 10%. Furthermore, the percent
loss of discharge capacity can be measured at any number of further
increments of 250 cycles. Accordingly, in the above example, the
discharge capacity can be measured again at 600 cycles and the
percent loss of discharge is calculated based on the difference
between the discharge capacity at 350 cycles versus the discharge
capacity at 600 cycles.
[0108] In a further embodiment, referring to FIG. 17, the percent
loss of discharge capacity over 100 cycle increments, beginning at
100 cycles after formation and with the last increment ending at
approximately 9,700 cycles is an average of 0.79%. In a further
embodiment, referring to FIG. 17, the percent loss of discharge
capacity over 100 cycle increments, beginning at 100 cycles after
formation and with the last increment ending at approximately 2,900
cycles is an average of 0.89%.
[0109] In a further embodiment, the percent loss of discharge
capacity over 100 cycle increments, beginning at 100 cycles after
formation, is at set forth in any of the 100 cycle increments shown
in Table 10 or any combination such increments.
[0110] In a further embodiment, the foregoing charge/discharge
cycles are carried out as follows for each cycle: (1) charging is
carried out according to the constant current constant voltage
(CCCV) method with charging, for example, at 0.5 C until the cell
potential reaches 3.6 volts at which time this potential is held
constant until the current reaches 0.1 C, at which time charging is
stopped and after a break of approximately 10 minutes, (2)
discharging is carried out at 0.5 C and is stopped when the cell
potential reaches 2.5 volts Approximately 60 minutes after step (2)
is completed, the foregoing is repeated for the next cycle. The
charge/discharge cycles are carried out at approximately 20 C and
approximately 1 bar (ambient) pressure.
[0111] In a further embodiment, the capacity, in embodiments of the
battery cell described herein, per unit area of the positive
electrode is at least 5 mAh/cm.sup.2, at least 7.5 mAh/cm.sup.2, at
least 10 mAh/cm.sup.2, at least 12.5 mAh/cm.sup.2 at least 15
mAh/cm.sup.2, at least 20 mAh/cm.sup.2 or at least 25
mAh/cm..sup.2. In a further embodiment, the capacity is from at
least 5 mAh/cm.sup.2 to 25 mAh/cm..sup.2
[0112] In a further embodiment, more than 90 percent of the
theoretical capacity of the active material in the positive
electrode is obtained in the cell.
[0113] In a further embodiment, the ampacity, in embodiments of the
battery cell described herein, per unit area of the positive
electrode is at least 10 mA/cm.sup.2, at least 50 mA/cm.sup.2 or at
least 150 mA/cm.sup.2. In a further embodiment, the ampacity is
from at least 10 mA/cm.sup.2 to 150 mA/cm.sup.2. In a further
embodiment, the ampacity is from at least 10 mA/cm.sup.2 to 200
mA/cm.sup.2. In a further embodiment, the ampacity is from at least
10 mA/cm.sup.2 to 300 mA/cm.sup.2.
[0114] In a further embodiment, the battery cell is fully charged
at approximately 3.6 volts and the overcharge potential
(electrochemical stability window) of the electrolyte is
approximately 4.0 volts. In a further embodiment, the battery cell
is fully charged at a voltage below the overcharge potential
(electrochemical stability window) of the electrolyte.
[0115] In a further embodiment, the self discharge of the battery
cell is about a five percent loss of charged capacity per
month.
[0116] Furthermore, in embodiments described herein, the
electrolyte is not flammable. For example, SO.sub.2 is not
flammable or combustible and accordingly, electrolyte embodiments
containing 100 percent SO.sub.2 and LiAlCl.sub.4 will also be
non-flammable and non-combustible. In further embodiments, amounts
and types of additional ingredients of the electrolytes are
provided that result in the electrolyte being non-flammable and
non-combustible at predetermined temperatures and predetermined
environmental conditions (e.g., the amount of oxygen to which the
electrolyte is exposed).
[0117] In a further embodiment, the cells described herein are in
conformance with the Projectile Test described on page 19 of
Underwriter's Laboratory UL 1642 Standard for Lithium Batteries,
Fourth Edition (Sep. 19, 2005), such test protocol herein
incorporated by reference in its entirety. That is, when subjected
to this test, no part of an exploding cell or battery shall
penetrate the wire screen described in the test such that some or
all of the cell or battery protrudes through the screen. In a
further embodiment, when the test protocol is applied, the cells
described herein will not ignite or burn out.
[0118] In a further embodiment, the electrolyte in the cells
described herein will not ignite or combust when the electrolyte or
the cell (that is, the cell housing) is placed above a Bunsen
burner and contacted with the tip of the Bunsen burner blue flame
for at least ten minutes or, alternatively, is exposed to a
temperature in excess of 800.degree. C. or a temperature of from
.degree.800 to 1000.degree. C. for at least ten minutes.
Separator
[0119] As used herein, the term "separator" means (1) a separator,
as that term is understood in the lithium ion rechargeable battery
field or (2) an insulator as that term (porous insulator) is
described, for example, in U.S. Patent Application Publication No.
20070065714.
[0120] Examples of insulator materials include particulate,
fibrous, or tubular pore structure materials, formed, for example,
from oxides, carbides, or chemically stable silicates. Further
examples of insulator materials include glass fiber, e.g., woven
glass or glass fleece. In a further embodiment, the insulator is
inert to the electrolytes described herein and, in a further
embodiment, inert to the overcharge and self discharge products of
the cells described herein.
[0121] Examples of commercially available woven glass materials are
listed below in Table 6.
TABLE-US-00006 TABLE 6 Company Name Product Name Culimenta HBO029
Norton Pampus GmbH 7614 Stottrop Textil Nr.124 Lange + Ritter GmbH
92125 Lange + Ritter GmbH 92140 Glasseiden GmbH TG 1000 Glasseiden
GmbH TG 430 Glasseiden GmbH TG 100P Interglas 4391 Interglas 92111
Interglas 461 Interglas 2037 Interglas 2034 Groning 2020140 Groning
2020290 Groning 30121060
[0122] In a further embodiment, the weight per unit area of the
woven glass insulator is approximately 128 g/m.sup.2, the warp is
approximately 47.3 fibers/cm, the weft is approximately 21
fibers/cm and the thickness is approximately 0.12 mm.
[0123] In a further embodiment, the insulator is made of woven
glass and is in the form of a pouch 24, in which the positive
electrode is placed (FIG. 6). In a further embodiment, as shown in
FIG. 6, the top of the pouch extends up to a portion of the current
collector connector 23. In a further embodiment, as shown in FIG.
6, the positive electrode in the pouch is configured between two
negative electrodes. In a further embodiment as shown in FIG. 6, in
this configuration, the tabs of the positive and negative
electrodes are on opposite ends.
Housing
[0124] In an embodiment, the cell is located in a housing. In a
further embodiment, the housing is cylindrical or prismatic. The
housing is made of a durable metal, for example, stainless steel.
In a further embodiment, the housing is designed to withstand the
corrosive effects of the electrolytes. In a further embodiment, the
housing is designed to last for more than 10 years of normal cell
use.
[0125] In a further embodiment, the housing is prismatic 27 and
comprises six sides, for example, four walls and a top cover 33 and
a bottom cover. In a further embodiment, the top cover 33 comprises
4 ports 32, namely an electrolyte filing port, a vent port and two
electrical ports.
[0126] In a further embodiment, an electrically conductive pole 28
is disposed in each electrical port, the pole being disposed in an
outer peripheral surface 29 which engages the cover to occlude the
port and wherein disposed between the outer peripheral surface and
the pole is an insulating surface 29. In an embodiment, the
foregoing is comprised in a glass-to-metal feedthrough 34 which
comprises an electrically conductive pole 28 disposed in a glass
insulator 29, which insulates the pole from the top cover 33,
wherein the insulator is disposed in an outer metal periphery
surface 29 that is sealed, for example, laser welded, to the top
cover 33 and the pole 28 extends through the cover 33 into the
interior of the housing. In a further embodiment, the pole 28
defines an interior passage allowing communication between the
inside and exterior of the housing. In a further embodiment, the
pole provides electrically conductive communication between the
inside and exterior of the housing but does not contain an interior
passage. In a further embodiment, the pole 28 extends through the
cover 33 into the interior of the housing and engages a portion of
the current collector connector 23.
[0127] In a further embodiment, a plug, for example a filling tube
30, is disposed in the electrolyte filling port. In an embodiment,
the plug engages the cover 33 to occlude the port and the plug
defines an interior passage which allows fluid communication
between the inside and exterior of the housing.
[0128] In a further embodiment, the vent port is occluded with a
surface layer designed to rupture or release when exposed to a
predetermined amount of pressure. In an embodiment, the surface
layer is a metal burst disk, 31. In a further embodiment, the
housing is hermetically sealed. In a further embodiment, the
glass-to-metal feedthrough, the electrolyte filling tube and the
burst disk are laser welded to the ports of the top cover and the
top and bottom covers are laser welded to the wails of the
housing.
Configuration of Electrodes in the Housing and Electrolyte
Filling
[0129] In an embodiment, as set forth in FIG. 6, two negative
electrodes are disposed on opposing sides of each positive
electrode and each positive electrode is disposed in a pouch 23
that prevents the physical contact of the positive electrode to
either of the negative electrodes.
[0130] In a further embodiment, a plurality of positive and
negative electrodes in the above configuration are enclosed in a
layer which prevents physical contact between the electrodes and
the housing. In an embodiment, the layer is an envelope 25, which
is folded over the electrodes. In a further embodiment, layer 25a
of the envelope is folded over a negative electrode on one end of
the plurality of electrodes, layer 25b of the envelope is folded
over a negative electrode on the other end of the plurality of
electrodes, layers 25c and 25d are folded over the exposed sides of
the negative electrodes and overlap with layer 25a to cover the
side edge of the negative electrode covered by 25a. In a further
embodiment, layers 25e are folded over the exposed bottom edge of
the negative electrodes.
[0131] In a further embodiment, the plurality of electrodes folded
in the envelope 26 is disposed in the housing as shown in FIGS. 8
and 9. In a further embodiment, the envelope snugly fits the
plurality of electrodes into the housing thereby minimizing any
displacement of the positioning of the electrodes in the housing
and furthermore preventing physical contact between the electrodes
and the housing. In a further embodiment, the housing contains 20
positive electrodes and 21 negative electrodes.
[0132] In a further embodiment, the housing containing the
plurality of electrodes folded in the envelope is filled with
electrolyte via the filling tube. In an embodiment, the electrolyte
rises to a level below the top of the envelopes so that the
electrolyte does not directly (other than through the pouch)
communicate between the positive and negative electrode.
[0133] In a further embodiment, the cell is filled with electrolyte
according to processes set forth in U.S. Patent Application
Publication No. 20070065714 (see for example FIG. 9 of the
20070065714 publication): In a further embodiment, [0134] 1. A cell
housing containing a positive and negative electrode is evacuated;
[0135] 2. The interior of the housing is filled with gaseous
SO.sub.2; [0136] 3. Steps 1 and 2 are optionally repeated; [0137]
4. The housing is evacuated; [0138] 5. A fill opening of the
housing is attached gas-tight to a vessel which contains an
electrolyte solution with a predetermined concentration of
SO.sub.2; and [0139] 6. The electrolyte solution is allowed to flow
into the housing driven by a pressure applied to the electrolyte
and by the vacuum present in the housing.
[0140] In a further embodiment, the cell is filled with electrolyte
according to processes set forth in set forth below in Table 7.
TABLE-US-00007 TABLE 7 In cell 1. Cool the cell to -20.degree. C.
housing 2. Evacuate the cell (e.g., for 10 min) with a standard
containing a vacuum. plurality of 3. Fill the cell with gaseous
100% SO.sub.2 (e.g., for ten electrodes: minutes) at an over
pressure of 1 bar. 4. Repeat step 2 and 3 two times. 5. Evacuate
the cell. 6. Fill the cell with electrolyte using an over pressure
on the electrolyte from 1 to 2.5 bar.
[0141] In a further embodiment, the dimensions of the housing,
positive electrode, pouch and negative electrode are as shown in
Table 8:
TABLE-US-00008 TABLE 8 Width Thickness Component Height (mm) (mm)
(mm) Housing 130 mm 130 24.5 Positive 106 mm (not including the
122.5 0.58 Electrode height of the conductive tab) Pouch 114-118 mm
127.5 0.82 Negative 110-111 mm (not including 127.5 0.32 Electrode
the height of the conductive tab)
[0142] In a further embodiment, the theoretically calculated
capacity of the positive electrodes in the cell is higher than that
of the negative electrodes, for example, by 20-30 percent.
Cover Layer Reducing Treatment
[0143] In an embodiment, the capacity stability of a cell with at
least one insertion electrode, for example, an intercalation
electrode, are increased by means of a treatment or pretreatment to
reduce the capacity required to create stable covering layers on at
least one insertion electrode. There are various embodiments to
this end.
[0144] A first embodiment is to subject the insertion electrode to
a temperature treatment. This applies in particular for carbon
electrodes, which are tempered at a temperature of at least
900.degree. C. under exclusion of oxygen (for example, under inert
gas) for at least 10, at least 20 and or at least 40 hours.
[0145] Alternatively or additionally, the capacity required to form
stable covering layers on a negative carbon electrode can be
reduced by using a graphite material with a relatively low specific
surface area.
[0146] According to a further embodiment, the pretreatment to
reduce the covering layers comprises providing the corresponding
electrode with a thin surface coating.
[0147] Such a surface coating can be effected in particular by
means of atomic layer deposition. This method has been used in
recent times for numerous purposes. An overview is given, for
example, in the publication, S. M. George "Atomic Layer Deposition:
An Overview", Chem. Rev. 2010, 111-131
[0148] The process parameters should be adapted to the requirements
of the electrode. In an embodiment, the negative electrode is
pretreated with NO.sub.2-TMA (nitrogen dioxide-trimethylaluminum).
This seeds an initial functional layer on the carbon, this layer
being advantageous for subsequent ALD treatment. In this context,
reference can additionally be made to G. M. Sundaram et al.
"Leading Edge Atomic Layer Deposition Applications", ECS
Transactions, 2008, 19-27.
[0149] In a further embodiment, coating by ALD is via a thin layer
of Al.sub.2O.sub.3. In a further embodiment, the ALD layer is
formed with SiO.sub.2.
[0150] A further embodiment for applying a surface coating suitable
for reducing the capacity required to establish a stable covering
layers is dip coating. To this end, either the insertion active
material intended for processing into the electrode or the whole
electrode is brought into contact with a reaction solution that
contains starting materials suitable for the formation of the
layer. A temperature treatment is then performed to form and harden
the layer. The following method can be used, for example.
[0151] Isopropanol, water, 1 molar hydrochloric acid and
tetraethylorthosilicate are mixed in a mole ratio of 3:1:1:1. The
solution is kept at room temperature. It is then diluted with
isopropanol in the volume ratio 1:1. The electrodes to be treated
are dipped in the reaction solution for 30 seconds or, if bubble
formation is observed, until bubble formation has stopped. The
electrodes are then dried in a drying cabinet at 200.degree. C.
without vacuum for 48 hours.
[0152] Embodiments of the battery cells described herein are for
use in high energy applications, such as, electric vehicles, energy
storage systems, including large scale energy storage system,
uninterruptible power supplies, back up batteries and for certain
medical devices. Further embodiments of the battery cells described
herein are for use in high power applications, such as, power
tools, hybrid vehicles, and certain medical devices.
[0153] In a further embodiment, battery cells described herein are
used as a power supply, optionally in combination with other power
supplies, and optionally as either a main or auxiliary power supply
for the following: portable electronic devices such as video
cameras, digital still cameras, cellular phones, notebook personal
computers, cordless telephones, headphone stereos, portable radios,
portable televisions and personal digital assistants (PDAs),
portable home appliances such as electric shavers, memory devices
such as backup power supplies and memory cards, power tools such as
electric drills and electric saws, medical electronic devices such
as pacemakers and hearing aids, and motor vehicles such as electric
vehicles, plug in electric vehicles and hybrid vehicles.
[0154] In a further embodiment, battery cells described herein are
used as an energy storage system and as a power supply for storing
power from and supplying power to an energy grid.
[0155] Referring to the embodiment of FIG. 1, the housing 1 of the
rechargeable battery cell 2 encloses an electrode arrangement 3
comprising a plurality (three in the case shown) of positive
electrodes 4 and a plurality (four in the case shown) of negative
electrodes 5. The electrodes 4, 5 are connected with corresponding
terminal contacts 9, 10 of the battery by means of electrode leads
6, 7.
[0156] The electrodes 4, 5 have a planar shape, i.e., they are
shaped as layers having a thickness which is small relative to
their extension in the other two dimensions. They are separated
from each other by separators 11. The housing 1 of the prismatic
cell shown is essentially cuboid, the electrodes and the wails
shown in cross-section in FIG. 1 extending perpendicularly to the
drawing plane and being essentially straight and flat. However, the
a further embodiment of the cell can be designed as a spirally
wound cell.
[0157] The electrodes 4, 5 comprise a current collector element,
which is made of metal and serves to provide the required
electronically conductive connection of the active material of the
respective electrode. The current collector element is in contact
with the active material involved in the electrode reaction of the
respective electrode.
[0158] In an embodiment, during manufacture of the electrode, the
active material is incorporated into the porous metal portion of
the current collector such that it fills the pores of the porous
metal, for example, uniformly over, for example, the whole
thickness of the porous metal. The active material is then pressed
under high pressure, the thickness after the pressing operation
being in an embodiment, no more than 50% or no more than 40%, of
the initial thickness. In a further embodiment, the active material
is distributed essentially homogeneously within the porous metal.
"Essentially" is to be construed such that the cell function is
only slightly impaired by any deviations. In a further embodiment,
the porous metal extends through at least 70% or at least
approximately 80%, of the thickness of the electrode.
[0159] A portion of an electrode is shown in FIG. 3, in the form of
an electron microscope image. The electrode material was cooled in
liquid nitrogen and then broken, because a cutting operation would
have corrupted the structural features. In spite of certain
material damage caused by breaking 12, features of the structure of
the portion of the positive electrode are visible in FIG. 3.
[0160] For the following Examples, positive electrodes containing
LiFePO.sub.4 active material were produced as follows.
[0161] A paste was produced using the following components: [0162]
94 wt. % LiFePO.sub.4, with carbon surface coating and a mean
particle size approximately 2-3 .mu.m [0163] 2 wt. % carbon black
as conductivity agent [0164] 4 wt. % THV as binding agent
[0165] First the binding agent was dissolved in acetone, then
carbon black was added to the solution while stirring, and finally
the active material was added alternately with further solvent,
also while stirring.
[0166] The paste was then incorporated homogeneously into nickel
metal foam having an initial porosity of more than 90%, and dried
for an hour at 50 C. After cooling, the electrode material was
pressed by means of a calendar to a thickness of 0.6 mm, starting
from an initial thickness of 1.7 mm. It was then subjected to a
tempering process at 180 C.
Example 1
[0167] Pieces with a size of 1 cm.sup.2 were cut out of the
electrode material. The pieces had a theoretical capacity of
approximately 13 mAh. The pieces were examined in an E-cell with a
three-electrode arrangement, in which the reference and counter
electrode were made of metallic lithium. The electrolyte used in
the E-cell had the composition of 1.5 moles SO.sub.2. per mole of
LiAlCl.sub.4.
[0168] In order to determine the discharge capacities of the
electrodes for different current loads, 40 charging and discharging
cycles were performed in the E-cells. Charging took place in each
case with the same charging rate of 1 C ("C" indicates that the
nominal capacity is charged or discharged in one hour). Discharging
took place after each charging operation, with the cells being
discharged at the following rates in the 40 cycles: [0169] 10
cycles 1 C [0170] 4 cycles each 2 C, 4 C, 8 C, 10 C, 15 C [0171] 10
cycles 1 C.
[0172] Charging took place up to a voltage of 3.7 V. Discharging
ended at a voltage of 3.2 V.
[0173] FIG. 11 shows, as mean values over eight experiments, the
discharge capacity Q.sub.D in mAh/g as a function of the cycle
number. The figure shows the percentage of nominal capacity
available the given discharge rates. As shown in the figure, when
the cell is discharged with at 10 C, approximately two thirds of
the nominal capacity is available.
[0174] FIG. 12 summarizes the results illustrated in FIG. 11,
showing the discharge capacity Q.sub.D as a function of the
discharge rate C (curve A). Curve B in FIG. 11 shows values from
the publication, Porcher et al., "Design of Aqueous Processed Thick
LiFePO4 Composite Electrodes for High-Energy Lithium Battery, J.
Electrochem. Soc., A133-A144 (2009). This publication describes the
production of, inter alia, electrodes having a thickness of 0.2 mm.
The electrodes are manufactured with a water-soluble binding agent
in aqueous suspension. The resulting capacity per unit area
("capacity density") is specified as 3 mAh/cm.sup.2, with loading
of 20 mg/cm.sup.2 and an electrode thickness of 200 .quadrature.m.
The measurement data plotted in FIG. 12 was taken from FIG. 1 on
Page A135 of the publication for the "CMC" material. FIG. 12 shows
that the capacity represented by curve B as decreasing with the
discharge rate faster than the capacity shown by Curve A. For a
discharge rate of 10 C, for example, the positive electrode
described in the publication and shown in Curve B has a discharge
capacity of 18 mAh/g compared with 100 mAh/g for Curve A. The
comparison is summarized by the following Table 9:
TABLE-US-00009 TABLE 9 Example 1 Porcher et al. Capacity per unit
area (mAh/cm.sup.2) 13 3 Loading with active mass (mg/cm.sup.2) 76
20 Electrode thickness (.mu.m) 600 200 Specific discharge capacity
for 10 C 100 18 (mAh/g)
[0175] FIG. 13 shows the values for the resistance R of the
positive electrode that were measured on the E-cells after
charging, as a function of the cycle number. In spite of the
discharge rates, the resistance of the electrode remains stable in
the range between 0.6 and 0.8 ohms.
[0176] For the below Examples 2 and 4, the negative electrode was
produced as follows. A paste was produced using 100% graphite
powder. The graphite was dissolved in acetone while stirring. The
paste was incorporated homogeneously into a metal foam having an
initial porosity of more than 90%, and dried for an hour at 50 C.
After cooling, the electrode material was pressed by means of a
calendar to a thickness of 0.3 mm, starting from an initial
thickness of 1.7 mm. It was then subjected to a tempering process
at 1000 C.
Example 2
[0177] For this Example, a spirally wound cell of the type Sub-C
was produced, the electrodes having a theoretical capacity of 17
mAh/cm.sup.2 and the positive electrodes containing LiFePO.sub.4 as
active material.
[0178] The electrodes were wound into a spiral together with a
separator positioned between them and placed in the Sub-C housing.
This was then filled with an electrolyte solution with the
composition .mu.6SO.sub.2 per mole LiAlCl.sub.4. The cell was
charged with a charging rate of 0.7 C to 831 mAh. The discharge
current was 10 A, corresponding to a discharge rate of 7 C.
Discharging was stopped at a cell voltage of 2 V and with an
extracted capacity of 728 mAh. This corresponds to 88% of the
charged capacity.
Example 3
[0179] Using a positive electrode produced as set forth above and a
positive electrode containing lithium cobalt oxide as the active
material, but otherwise having corresponding features, the
dependence of the capacity on the number of charging and
discharging cycles (each with 1 C) in an E-cell was determined.
[0180] FIG. 14 shows the results obtained using an SO.sub.2
electrolyte containing 1.5 mole SO.sub.2 per mole of conductive
salt (lithium tetrachloroaluminate). The discharge capacity Q.sub.D
in percent of the theoretical value is plotted against the number
of charging and discharging cycles performed, where curve A relates
to the LiFePO.sub.4 electrode and curve B to the lithium cobalt
oxide electrode. The curves show the amount of the theoretical
capacity obtained with the LiFePO.sub.4 electrodes, whereas on
average only around 60% of the theoretical capacity is shown in
curve B.
[0181] FIG. 15 shows the results of an experiment that differed
from the experiment that served as a basis for FIG. 14 with respect
to the concentration of the conductive salt in the electrolyte. In
this case it was 4.5 mole SO.sub.2 per mole of LiAlCl.sub.4. The
figure shows that the percent decrease in capacity for the
LiFePO.sub.4 electrode (curve A) versus the lithium cobalt oxide
electrode (curve B).
Example 4
[0182] FIG. 16 shows the results of an experiment in an HPCM cell
(two negative electrodes and one positive electrode), with the
positive electrode containing LiFePO.sub.4 with a theoretical
capacity of 19 mAh/cm.sup.2 (curve A), compared with a HPCM cell
with a positive electrode based on lithium cobalt oxide (curves B),
but otherwise having corresponding features. For both curves, the
electrolyte contained 6 moles of SO.sub.2 per mol LiAlCl.sub.4.
[0183] The discharge capacity Q.sub.D in percent of the nominal
value is plotted against the number of cycles. After an initial
decrease, the extractable capacity for the cell is substantially
constant versus the comparison cell.
[0184] FIG. 17 shows the results of a long-duration test with a
cell of the type used in FIG. 9, curve A, where the extracted
capacity Q.sub.D is again plotted against the number of cycles. The
figure shows approx. 9,700 cycles, in which the reduction in the
extractable capacity per 100 cycles as set forth in Table 10
below.
[0185] Table 10 shows the reduction in capacity per 100 cycles for
the data shown in the curves of FIG. 16 (curve A) and FIG. 17. The
increments beginning at 3100 are shown in Table 10 as 200 cycle
increments but the delta is calculated based on 100 cycle
increments (that is the delta is averaged over the two 100 cycle
increments).
TABLE-US-00010 TABLE 10 cycle discharge capacity (% of delta
between 100 number max. discharge capacity) cycle increments 100
75.50% 5.70% 200 69.80% 3.20% 300 66.60% 2.30% 400 64.30% 1.60% 500
62.70% 1.50% 600 61.20% 1.20% 700 60.00% 1.00% 800 59.00% 0.80% 900
58.20% 0.50% 1000 57.70% 0.70% 1100 57.00% 0.50% 1200 56.50% 0.50%
1300 56.00% 0.50% 1400 55.50% 0.50% 1500 55.00% 0.50% 1600 54.50%
0.50% 1700 54.00% 0.30% 1800 53.70% 0.50% 1900 53.20% 0.40% 2000
52.80% 0.30% 2100 52.50% 0.30% 2200 52.20% 0.40% 2300 51.80% 0.30%
2400 51.50% 0.30% 2500 51.20% 0.40% 2600 50.80% 0.10% 2700 50.70%
0.40% 2800 50.30% 0.30% 2900 50.00% 0.20% 3000 49.80% 0.30% 3100
49.50% 0.50% 3300 49.00% 0.50% 3500 48.50% 0.50% 3700 48.00% 0.50%
3900 47.50% 0.50% 4100 47.00% 0.50% 4300 46.50% 0.50% 4500 46.00%
0.50% 4700 45.50% 0.00% 4900 45.50% 0.50% 5100 45.00% 0.30% 5300
44.70% 0.70% 5500 44.00% 0.50% 5700 43.50% 0.50% 5900 43.00% 0.50%
6100 42.50% 0.50% 6300 42.00% 1.00% 6500 41.00% 0.70% 6700 40.30%
0.50% 6900 39.80% 0.10% 7100 39.70% 0.40% 7300 39.30% 0.50% 7500
38.80% 0.63% 7700 38.17% 0.50% 7900 37.67% 2.00% 8100 35.67% 0.34%
8300 35.33% 0.50% 8500 34.83% 1.33% 8700 33.50% 0.50% 8900 33.00%
0.33% 9100 32.67% 0.67% 9300 32.00% 0.33% 9500 31.67% 0.34% 9700
31.33% --
Example 5
[0186] FIG. 19 shows the percent of maximum discharge capacity
versus cycle number for HPCM cells containing positive electrodes
with lithium cobalt oxide as the active material and negative
electrodes in accordance with the description above in an
electrolyte having mole ratios of 1.0, 1.5, 3.0, 4.5, and 6.0
SO.sub.2 per mole of LiAlCl.sub.4 and shows a decreasing trend with
increasing amounts of SO.sub.2 per mole of LiAlCl.sub.4. The breaks
in the curve for 3.0 SO.sub.2 reflect a failure of a cell(s) in the
experiment.
[0187] FIG. 20 shows the percent of maximum discharge capacity
versus cycle number for HPCM cells containing positive electrodes
with LiFePO.sub.4 as the active material and negative electrodes in
accordance with the description above in an electrolyte having mole
ratios of 1.5, 4.5, 6.0, 10.0 and 22.0 SO.sub.2 per mole of
LiAlCl.sub.4 and shows an increasing and then stabilized trend as
amounts of SO.sub.2 per mole of LiAlCl.sub.4 are increased. The
breaks in the curves for 22.0, 6.0 and 10.0 SO.sub.2 indicate a
failure of cell(s) in the experiment.
Example 6
[0188] Table 11 below lists the amount of capacity consumed, based
on a percentage of theoretical capacity, to form a stable SEI layer
at increasing amounts of SO.sub.2 per mole of LiAlCl.sub.4 for
cells with LiFePO.sub.4 positive electrodes compared to lithium
cobalt oxide positive electrodes. With both active materials, a
decreased amount of capacity is consumed with the increase in
SO.sub.2 per mole of LiAlCl.sub.4 from 1.00 to 6.00.
TABLE-US-00011 TABLE 11 SEI formation capacity (% of the
theoretical SO.sub.2 per mole capacity of the positive electrode)
LiAlCl.sub.4 LiCoO.sub.2 LiFePO.sub.4 1.00 23.52 26.96 1.50 21.16
22.58 3.00 21.85 21.52 4.50 18.73 18.94 6.00 15 16.98
Example 7
[0189] FIG. 18 shows the results of an experiment with the
following electrode materials: [0190] Curve A negative electrode
without cover-layer-reducing pretreatment. [0191] Curve B negative
electrode where the active material was pretreated by means of dip
coating with formation of an SiO.sub.2 layer, before incorporation
in the electrode. [0192] Curve C negative electrode that was
pretreated as a whole by means of dip coating with formation of an
SiO.sub.2 layer.
[0193] The three experimental electrodes were examined in an
E-cell. During charging of the electrode, the voltage U against
lithium was plotted in volts against the charge state Q, as
fraction of the nominal capacity Q.sub.N. The three graph groups
illustrated show the results of several experiments in each case
with the above-described electrodes. It is evident that the
capacity loss for the two pretreated electrodes is less than for
the untreated electrode, the electrode pretreated in its entirety
being slightly better than the other pretreated electrode. It is
noted that the data in Curve C has not yet been reproduced in an
HPCM cell.
[0194] Battery cells with SO.sub.2 electrolytes are described in
the following documents which are herein incorporated by reference
in their entirety, for example: [0195] U.S. Pat. No. 5,213,914
[0196] WO 00/44061 and U.S. Pat. No. 6,709,789 [0197] WO 00/79631
and U.S. Pat. No. 6,730,441 [0198] WO 2005/031908 and US
2007/0065714 [0199] L. Zinck et al. "Purification process for an
inorganic rechargeable lithium battery and new safety concepts", J.
Appl. Electrochem., 2006, 1291-1295 [0200] WO 2008/058685 and US
Patent Application 2010/0062341 WO 2009/077140
[0201] All the patent documents and other publications cited herein
are hereby incorporated by reference in their entirety.
* * * * *