Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-08-25
2001-09-11
Weiner, Laura (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S213000, C526S243000, C526S247000, C526S255000
Reexamination Certificate
active
06287722
ABSTRACT:
FIELD OF THE INVENTION
The present invention involves a process for melt forming conductive compositions comprising ionomers into multi-layer electrochemical cells suitable for use in electrochemical applications such as batteries, fuel cells, electrolysis cells, ion exchange membranes, sensors, electrochemical capacitors, electro-chromic windows, and modified electrodes. Of particular interest is the use in lithium batteries.
BACKGROUND
Cook et al., U.S. Pat. No. 4,818,643, discloses an extrusion process of polymer electrolyte materials and/or cathode materials, optionally extruded onto other components of a cell, including current collectors, sequentially or by coextrusion. Example 8 therein describes the addition of propylene carbonate to a melt blend of polyethylene oxide and salt in a second extrusion stage.
Gozdz et al., U.S. Pat. No. 5,418,091, discloses a “dry film” process involving the use of a temporary plasticizer in an electrolyte composition comprising a copolymer of vinylidene fluoride (VF2) and hexafluoropropylene (HFP), the temporary plasticizer being employed to provide voids in the solid polymer after removal thereof, and the temporary plasticizer being removed in a later step and subsequently replaced by of the hygroscopic lithium salt solution. The temporary plasticizer permits the early stages of the cell formation process to be run without undue concern about moisture. Gozdz does not disclose a melt extrusion process.
Schmutz et al., U.S. Pat. No. 5,470,357, discloses melt extrusion of the compositions of Gozdz, op.cit. Schmutz teaches a process of pretreating the current collector with a solution of a polymer similar to the polymer of the solid polymer electrolyte to facilitate lamination. The lamination may be performed utilizing calender rolls. The process otherwise is similar to that of Gozdz.
Chern et al., WO 97/44847 discloses an extrusion process for forming an activated electrode suitable for use in batteries, the process comprising mixing a non-ionic polymer, an electrode-active material, a salt, and organic carbonates and feeding the mixture to the feed zone of an extruder, mixing the ingredients therein, and extruding a film suitable for laminating to other components of the battery.
Keller et al., U.S. Pat. No. 5,725,822 discloses extrusion of an activated electrode composition the process comprising feeding a mixture of a (non-ionic) polymer, an electrode-active material, a salt, and organic carbonates to the upstream end of a screw extruder, and feeding additional solvent (or possibly a mixture of polymer and solvent) at a downstream port. The amount of solvent in the first feeding stage is adjusted to provide a melt undergoing sufficient shear that good mixing will occur, and the amount of solvent being fed in the second stage being adjusted so that the total amount of solvent represents the final amount in the finished electrode material. The extruded electrode may be deposited onto a current collector and/or coated with a layer of solid polymer electrolyte. Assembly of a lithium battery cell from thus extruded components is also disclosed.
Doyle et al., WO 98/20573, disclose the use of perfluoroionomers to form the electrodes and separators of electrochemical cells. In particular, the lithium ionomers are employed to form lithium-ion cells. The electrodes and separators are formed by casting solutions and dispersions onto a substrate, followed by a drying step, which in turn is followed by a solvent contact step. Combination of these components into electrochemical cells is also disclosed.
SUMMARY OF THE INVENTION
The present invention provides for a process for forming ionically conductive shaped articles, the process comprising:
combining in a vessel provided with a mixing means a polymer comprising monomer units of vinylidene fluoride and 2-50 mol-% of a perfluoroalkenyl monomer unit having a pendant group comprising the radical represented by the formula
—(OCF
2
CFR)
a
OCF
2
(CFR′)
b
SO
2
X
−
(M
+
)[YZ
c
]
d
(I)
wherein
R and R′ are independently selected from F, Cl or a perfluoroalkyl group having 1 to 10 carbon atoms, optionally substituted by one or more ether oxygens;
a=0, 1 or 2;
b=0 to 6;
M
+
is H
+
or a univalent metal cation;
X is O, C or N with the proviso that d=0 when X is O and d=1 otherwise, and c=1 when X is C and c=0 when X is N;
when c=1, Y and Z are electron-withdrawing groups selected from the group consisting of CN, SO
2
R
f
,SO
2
R
3
, P(O)(OR
3
)
2
, CO
2
R
3
, P(O)R
3
2
, C(O)R
f
, C(O)R
3
, and cycloalkenyl groups formed therewith wherein R
f
is a perfluoroalkyl group of 1-10 carbons optionally containing one or more ether oxygens;
R
3
is an alkyl group of 1-6 carbons optionally substituted with one or more ether oxygens, or an aryl group optionally further substituted;
or, when c=0, Y may be an electron-withdrawing group represented by the formula —SO
2
R
f
′ where R
f
′ is the radical represented by the formula
—(R
f
″SO
2
N−(M
+
)SO
2
)
m
R
f
″
where m=0 or 1, and R
f
″ is —C
n
F
2n
— and R
f
′″ is —C
n
F
2n+1
where n=1-10 and, a polar aprotic liquid to form a composition; mixing said composition at least until it is plastically formable; and, forming a shaped article from said plastically formable composition by the application of heat and/or pressure thereto.
The present invention further provides a shaped article made by the process of the invention.
The present invention further provides an electrochemical cell formed from one or more shaped articles of the invention.
The present invention still further provides for a process for forming an electrochemical cell, the process comprising combining in a vessel provided with a mixing means a polymer comprising monomer units of vinylidene fluoride and 2-50 mol-% of a perfluoroalkenyl monomer unit having a pendant group comprising the radical represented by the formula
—(OCF
2
CFR)
a
OCF
2
(CFR′)
b
SO
2
X
−
(M
+
)[YZ
c
]
d
(I)
wherein
R and R′ are independently selected from F, Cl or a perfluoroalkyl group having 1 to 10 carbon atoms, optionally substituted by one or more oxygens;
a=0, 1, or 2;
b=0 to 6;
M
+
is H
+
or a univalent metal cation;
X is O, C or N with the proviso that d=0 when X is O and d=1 otherwise, and c=1 when X is C and c=0 when X is N;
when c=1, Y and Z are electron-withdrawing groups selected from the group consisting of CN, SO
2
R
f
,SO
2
R
3
, P(O)(OR
3
)
2
, CO
2
R
3
, P(O)R
3
2
, C(O)R
f
, C(O)R
3
, and cycloalkenyl groups formed therewith wherein R
f
is a perfluoroalkyl group of 1-10 carbons optionally containing one or more oxygens;
R
3
is an alkyl group of 1-6 carbons optionally containing oxygen, or an aryl group optionally further substituted; or, when c=0, Y may be an electron-withdrawing group represented by the formula —SO
2
R
f
′ where R
f
′ is the radical represented by the formula
—(R
f
″SO
2
N—(M
+
)SO
2
)
m
R
f
′″
where m=0 or 1, and R
f
″ is —C
n
F
2n
— and R
f
′″ is —C
n
F
2n+1
where n=1-10. and, a polar aprotic liquid to form a composition; mixing said composition at least until it is plastically formable; and, forming a shaped article from said plastically formable composition by the application of heat and/or pressure thereto; layering said shaped article with such other shaped articles as are required to make an electrochemical cell; and, consolidating said layered shaped articles to form an electrochemical cell.
DETAILED DESCRIPTION
Highly conductive compositions comprising fluorinated ionomers provide numerous advantages in use in electrochemical applications such as lithium batteries. They are single ion conductors not susceptible to performance degrading charge polarization, exhibit high stability, and can be combined with aprotic polar solvent
Barton Kelly David
Doyle Christopher Marc
Farnham William Brown
Lang Charlie David
Vidal Antonio
E. I. du Pont Nemours and Co.
Weiner Laura
LandOfFree
Continuous melt process for fabricating ionically conductive... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous melt process for fabricating ionically conductive..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous melt process for fabricating ionically conductive... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541959