Unitary separator and electrode structure and method of manufacturing separator

• US 6,042,965 A
• Filed: 12/12/1997
• Issued: 03/28/2000
• Est. Priority Date: 12/12/1997
• Status: Expired due to Term

• Current Assignee: Johanson Manufacturing Corporation
• Original Assignee: Johnson Researach and Development Company Incorporated
• Inventors: Schneider, Daniel A., Stachoviak, Timothy J., Nestler, Joseph P., Craanen, Shirley A.
• Primary Examiner(s): Kalafut, Stephen
• Assistant Examiner(s): Crepeau, Jonathan
• Application Number:
  US08/989,803
• Time in Patent Office: 837 Days
• Field of Search: 429/247, 429/249, 429/253, 429/254, 429/142, 429/129, 429/131, 429/132, 429/133, 429/136, 429/137, 429/162, 429/209, 429/246, 429/217, 29/623.1, 29/623.5
• US Class Current: 429/129
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/426 Fluorocarbon polymers
• CPC Class Codes: H01M 50/46 Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49115 including coating or impregnating

Abstract

A secondary battery separator comprises a fibrous core embedded in a polymeric sheet having improved electrode fusion thereto in unitary construction. In the process of manufacturing the separator, a fibrous, polymeric, substantially two-sided core matrix is coated with a polymer mixture containing a plasticizer and a solvent vehicle, and a vacuum is applied to the reverse side from the coated side to cause the polymer mixture to penetrate and infuse the capillary voids of the core matrix from the opposite coated side. The vacuum is continued until the solvent vehicle is fully volatilized. After the solvent vehicle has dissipated, the fiber matrix is turned over, and the process is repeated by applying a coating of polymer mixture to the second side and pulling a vacuum on the opposite side to cause penetration of the matrix.

Claims

1. A battery comprising:

an ion permeable, porous sheet made of a polymeric material;

a fiber matrix separator core embedded within said porous sheet, said fiber matrix separator core defining a plurality of interstitial voids which are occupied by said polymeric material sheet;

a cathode fused with one side of said polymeric material sheet; and

an anode fused with another, opposite side of said polymeric material sheet,

whereby the fusion eliminates a line of demarcation between the separator and the cathode and between the separator and the anode so as to allow a low resistance, transition region between the cathode and separator and between the anode and separator.

2. A battery comprising:

a substantially flat fiber matrix separator core having a first surface and a second surface facing opposite the first surface, said matrix separator core having a thickness extending between the first and second surfaces, said matrix separator core defining a plurality of interstitial voids extending through the thickness of the matrix separator core,

a cathode mounted adjacent said first surface of said fiber matrix separator core,

an anode mounted adjacent said second surface of said fiber matrix separator core,

a unitary, ion permeable, porous polymeric sheet having said matrix embedded therein, said polymeric sheet occupying the interstitial voids of the matrix core, and said polymeric sheet fused with said cathode and said anode to form a unitary structure with the separator,

whereby the fusion eliminates a line of demarcation between the separator and the cathode and between the separator and the anode so as to allow a low resistance, transition region between the cathode and separator and between the anode and separator.

3. An electrochemical cell comprising a sheet of ion permeable polymeric material with a cathodic domain populated with cathodic material interspersed with said polymeric material, an anodic domain populated with anodic material interspersed with said polymeric material, and a separator core embedded within said polymeric material between said anodic domain and said cathodic domain.

4. A process for manufacturing a battery separator comprising the steps of:

coating a fibrous polymeric core matrix having two sides with one or more coatings of a polymer mixture containing a solvent plasticizer and a solvent vehicle to the first side;

applying a vacuum to the reverse side of said polymeric core matrix causing the polymer mixture to penetrate and infuse the capillary voids of the core matrix;

continuing said vacuum until said solvent vehicle is fully evaporated;

applying one or more second coating of polymer mixture to the second side of said matrix;

applying a vacuum to the reverse side thereof causing the polymer mixture to further penetrate and infuse the capillary voids of said matrix, and further causing the polymer boundaries penetrating from each said matrix side to merge; and

continuing said vacuum until said solvent vehicle is fully evaporated.

5. The method of claim 4 wherein sufficient polymer mixture is applied to the two sides of said matrix to provide a layer of polymeric material overlying the first side of the matrix core and to further provide a layer of polymeric material overlying the second side of said matrix core.