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US 5,961,671 AGranted
Apparatus and method of preparing electrochemical cells
AssigneeValence Technology, Inc.
InventorsWade Guindy, Steven D. Cochran, Carl Richwine, George Adamson, Porter H. Mitchell
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Abstract
A method for removing plasticizers such dibutyl phthalate from the anode, cathode, and polymeric matrix components of electrochemical cell precursors using carbon dioxide in the supercritical state is provided. The method forms porous polymeric structures that enhances the mass transport of ions in the cell which results in improved electrochemical performance.
Claims30
A method of preparing an electrochemical cell comprising an anode, a cathode, and a polymeric layer interposed between the anode and cathode which comprises the steps of:
- (a) forming an anode composition comprising a carbon material, a first polymer, and a first plasticizer;
- (b) forming a cathode composition comprising a cathode active material, a second polymer, and a second plasticizer;
- (c) forming a polymeric matrix comprising a third polymer and third plasticizer that is interposed between the anode composition and cathode composition, wherein the polymeric matrix formed has a first surface that is attached to a surface of the cathode composition and a second surface that is attached to a surface of the anode composition;
- and
- (d) removing said first, second, and third plasticizers by extraction with a supercritical fluid comprising carbon dioxide to form an electrochemical cell precursor which comprises contacting said anode composition, cathode composition, and polymeric matrix to said supercritical fluid, wherein said supercritical fluid during said contacting is maintained for a sufficient length of time such that the supercritical fluid takes up at least a portion of said plasticizers, and wherein during said contact the temperature of the supercritical fluid is maintained between about 32.degree. C. to 60.degree. C. and the pressure of the supercritical fluid is maintained between about 1,100 psi to 4,000 psi and wherein step (d) substantially does not cause any detachment of the cathode composition from the first surface of the polymeric matrix and substantially does not cause detachment of the anode composition from the second surface of the polymeric matrix.
2 more elements
A method of preparing an electrochemical cell comprising an anode, a cathode, and a polymeric layer positioned between the anode and cathode which comprises the steps of:
- (a) forming an anode composition comprising a carbon material, a first polymer, and a first plasticizer;
- (b) forming a cathode composition comprising a cathode active material, a second polymer, and a second plasticizer;
- (c) forming a polymeric matrix comprising a third polymer and a third plasticizer that is positioned between the anode composition and cathode composition wherein the polymeric matrix formed has a first surface that is attached to a surface of the cathode composition and a second surface that is attached to a surface of the anode composition;
- and
- (d) removing said first, second, and third plasticizers by extraction with a supercritical fluid to form an electrochemical cell precursor by a process comprising the steps of:
- (i) providing an apparatus that comprises:
- a sealable chamber defining a compartment adapted to receive an article containing a plasticizer;
- means for circulating a supercritical fluid into said compartment that comes into contact with said article;
- and
- means for separating supercritical fluid and plasticizer from a mixture of supercritical fluid and plasticizer;
- (ii) placing said anode composition, cathode composition, and polymeric matrix into said compartment and contacting the same with a supercritical fluid that comprises carbon dioxide, wherein said supercritical fluid during said contacting is maintained for a sufficient length of time such that the supercritical fluid takes up at least a portion of said plasticizers, and wherein during said contact the temperature of the supercritical fluid is maintained between about 32.degree. C. to 60.degree. C. and the pressure of the supercritical fluid is maintained between about 1,100 psi and 4,000 psi;
- and
- (iii) removing said supercritical fluid loaded with said portion of plasticizer taken up during said contacting wherein step (d) substantially does not cause any detachment of the cathode composition from the first surface of the polymeric matrix and substantially does not cause detachment of the anode composition from the second surface of the polymeric matrix.
10 more elements
Dependencies are inferred from the claim text.