Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
2000-08-10
2003-09-09
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S247000, C429S249000, C252S062200
Reexamination Certificate
active
06617078
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to lithium ion rechargeable batteries utilizing polymer electrolytes.
BACKGROUND OF THE INVENTION
Rechargeable lithium batteries utilizing polymer electrolytes are well known see Handbook of Batteries by David Linden, (c) 1995, chapter 36. The basic structure contains a lithium anode, a polymer electrolyte, a cathode and a current collector.
Secondary, lithium-ion cells and batteries are well known in the art. One such lithium-ion cell comprises essentially a lithium-intercalatable carbonaceous anode, a lithium-intercalatable chalcogenide cathode, and a non-aqueous, lithium-ion-conducting electrolyte there between. The carbon anode comprises any of the various forms of carbon (e.g., coke or graphite) pressed into a porous conductor or bonded to an electrically conductive carrier (e.g. copper foil) by means of a suitable organic binder. A known chalcogenide cathode comprises a crystalline spinel form of manganese oxide bonded to an electrically conductive carrier (e.g., aluminum foil) by a suitable organic binder such as ethylene propylene diene monomer (EPDM).
Lithium-ion cell electrolytes comprise a lithium salt dissolved in a vehicle which may be (1) completely liquid, or (2) an immobilized liquid, (e.g. gelled, or entrapped in a polymer matrix), or (3) a pure polymer. Known polymer matrices for entrapping the electrolyte include polyacrylates, polyurethanes, polydialkylsiloxanes, polymethylacrylates, polyphosphazenes, polyethers, polyvinylidene fluorides and polycarbonates, and may be polymerized in situ in the presence of the electrolyte to trap the electrolyte therein as the polymerization occurs. Known polymers for pure polymer electrolyte systems include polyethylene oxide (PEO), polymethylene-polyethylene oxide (MPEO) or polyphosphazenes (PPE). Known lithium salts for this purpose include, for example, LiPF
6
, LiClO
4
, LiBF
4
, LiAsF
6
, LiSbF
6
, LiSCN, LiAlCl
4
, LiCF
3
SO
3
, LiN(CF
3
SO
2
)
2
, LiC(CF
3
SO
2
)
3
, LiC
2
F
5
SO
3
, and LiN(C
2
F
5
SO
2
)
2
. Known organic solvents (i.e., vehicles) for the lithium salts in carbonate, ethylene carbonate, dialkyl carbonates, cyclic ethers, cyclic esters, glymes, lactones, formates, esters, sulfones, nitriles, and oxazolidinones.
Lithium cells made from pure polymer electrolytes, or liquid electrolytes entrapped in a polymer matrix, are known in the art as “lithium-polymer” cells, and the electrolytes therefore are known as polymeric electrolytes. Lithium-polymer cells are often made by laminating thin films of the anode, cathode and electrolyte together wherein the electrolyte layer is sandwiched between the anode and cathode layers to form an individual cell, and a plurality of such cells are bundled together to form a higher energy/voltage battery. In making such cells, it is desirable that the thin films are flexible and robust so that they can be handled without damage.
Frequently, polymer electrolytes utilized in lithium polymer batteries display high temperature instability due to the interaction of polymer binders and electrolytes resulting in dissolution and gelling. The use of such lithium polymer batteries therefore are limited in their use in starting, lighting and ignition (SLI) batteries, electric vehicle (EV) batteries, and hybrid vehicle (HV) batteries.
It is an object of the present invention to provide a chlorinated polymer based polymer electrolyte and electrodes for lithium ion rechargeable batteries. It is also an object of the present invention to provide polymer electrolytes and electrodes that are useful when operating at high temperatures.
SUMMARY OF THE INVENTION
Provided is a lithium ion rechargeable battery having a negative electrode, a positive electrode and a separator/polymer electrolyte there between comprising a chlorinated polymer. The polymer is comprised of a chlorinated polyvinyl chloride (PVC) blended with a terpolymer comprised of poly(vinylidene chloride-co-acrylonitrile-co-methyl methacrylate)s, poly(vinylidene chloride-co-methacrylonitrile-co-methyl methacrylate)s or combinations thereof.
Also provided is a negative electrode in a lithium ion rechargeable battery comprising a current collector and applied thereto a mixture of a chlorinated polymer and carbon-based materials. Also provided is a positive electrode in a lithium battery comprising a current collector and applied thereto a mixture of a chlorinated polymer and active materials.
Also provided is a separator in a lithium ion rechargeable battery, comprised of a chlorinated polymer and filler.
Also described is a lithium ion rechargeable battery comprised of (a) a negative electrode and (b) a positive electrode both comprised a current collector and applied to each, a mixture of a chlorinated polymer and active materials and (c) a separator comprised of a chlorinated polymer and filler.
Also provided is a method of manufacturing an electrode for use in a lithium ion rechargeable battery comprising preparing a mixture of a chlorinated polymer and active materials and applying the mixture to a substrate to be used as the electrode in the lithium ion rechargeable battery.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention pertains to separator/polymer electrolytes and electrodes made of a chlorinated polymer useful in lithium ion batteries, preferably rechargeable lithium ion batteries.
The rechargeable lithium ion cells which use solid polymer electrolytes (SPE) or plasticized polymer electrolytes are considered to have a safety advantage over the organic liquid electrolytes because of the absence or reduced amount of a volatile, and sometimes flammable, organic solvent. In their most common forms, these cells use a lithium-ion conducting polymer membrane which acts both as the separator and as the electrolyte, carbon-containing material(s) backed by a metal current collector as the negative electrode or the anode, and transition metal oxide(s) or chalcogenide(s), blended with conductive carbon and backed by a metal current collector as the positive electrode or the cathode.
The cell reaction shown below is similar to that in a liquid organic electrolyte cell. The electrochemical process of the anode is the uptake of lithium ion during the charge and the release of lithium ion during the discharge. Therefore, the anode acts as lithium ion source whereas the cathode acts as lithium ion sink during the discharge.
Overall Reaction
Li
x
C
6
+
A
y
B
z
⇌
charge
discharge
6
C
+
Li
x
A
y
B
z
Preferably, the chlorinated PVC is blended with a terpolymer of vinylidene chloride. It showed enhanced high temperature stability and also displayed mechanical integrity in the as-cast and extracted separator films. If using vinylidene chloride terpolymer alone as the polymer binder, the as-cast separator shows good mechanical properties, but it becomes very brittle with poor handelability after the removal of plasticizer, a step used to produce porous membrane. Separately, if using chlorinated PVC alone as the polymer binder, the as-cast separator film appears to be tacky and hence limits its application. It is the blending of chlorinated PVC and terpolymer of vinylidene chloride, which provides the most desirable mechanical properties.
Chlorinated PVC is a well-known commercially available material. A number of U.S. patents describe the manufacture and use of such materials such as, U.S. Pat. No. 5,821,304; and U.S. Pat. No. 5,789,543. Preferably, the amount of chlorine is at least 57 percent bound chlorine in the polymer. Preferred chlorinated PVC resins of different molecular weights and chlorine contents are available under the name TempRite (trademark of B.F. Goodrich of Cleveland, Ohio). It is preferred that the chlorinated PVC polymer is blended with other polymeric materials. Preferred polymeric materials to be blended with the chlorinated PVC are polymers of vinylidene chloride. Even more preferred polymers are those that are terpolymers of vinylidene chloride and different terpolymers.
Vinylidene chloride
Chia Yee-Ho
Jones-Coleman Janice
Parsian Mohammad
Snyder Kent A.
Delphi Technologies Inc.
Dobrowitsky Margaret A.
Mercado Julian
Ryan Patrick
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