Densification of compressible layers during electrode lamination
View Patent ↗A compressible and deformable layer is densified and laminated to a layer of a material that is relatively resistant to stretching. The densification and bonding take place in a single step. As used in fabrication of electrodes, for example, electrodes for double layer capacitors, a deformable and compressible active electrode film is manufactured from activated carbon, conductive carbon, and a polymer. The electrode film may be bonded directly to a collector. Alternatively, a collector may be coated with a wet adhesive layer. The adhesive layer is subsequently dried onto the foil. The dried adhesive and foil combination may be manufactured as a product for later sale or use, and may be stored as such on a storage roll or other storage device. The active electrode film is overlayed on the metal foil, and processed in a laminating device, such as a calender. Lamination both densifies the active electrode film and bonds the film to the metal foil. Spreading of the active electrode film in the plane parallel to the plane of the metal foil is reduced or eliminated during lamination, because of the adhesion between the film and the foil.
1. A method of manufacturing an electrode product, the method comprising:
providing a current collector comprising a first surface;
dry mixing dry active electrode material and dry binder;
providing a dry film of the dry mixed dry active electrode material and dry binder;
stacking the dry film and the current collector so that the first surface is in contact with the dry film; and
laminating the current collector and the dry film by pressing the current collector and the dry film to cause the dry film to densify and to adhere to the first surface, thereby obtaining a laminated electrode product;
wherein the step of laminating is performed so that the dry film is densified without spreading to an extent necessitating trimming of the dry film after laminating and wherein the step of lamination comprises processing the dry film and the current collector between rolls of a laminator the dry film and the current collector pass between a first laminator roll and a second laminator roll; and
the step of processing further comprises setting a gap between the first laminator roll and the second laminator roll so that thickness of the dry film is reduced by between about 30 and about 70 percent, the step of setting a gap being performed before the dry film and the current collector pass between the first and second laminator rolls.
2. The method of manufacturing an electrode according to claim 1 , wherein the step of providing a current collector comprises providing the current collector with a dried layer of adhesive material.
3. The method of manufacturing an electrode according to claim 1 , wherein the step of providing a current collector comprises providing the current collector comprising a material that causes the current collector to be capable of stretching to a lesser degree than the dry film.
4. The method of manufacturing an electrode according to claim 1 , wherein laminating consists of a single pass through a laminator.
5. The method of manufacturing an electrode according to claim 1 , wherein the dry film is not separately densified.
6. The method of manufacturing an electrode according to claim 1 , wherein the step of lamination is performed so as not to cause the dry film to spread beyond the current collector.
7. The method of manufacturing an electrode according to claim 1 , wherein the step of mixing comprises: dry mixing the dry particles of active electrode material with dry polymer and a conduction promoter to form a dry powder material; and wherein the step of providing the dry film comprises: fibrillizing the dry powder material using a dry high-shear technique.
8. The method of manufacturing an electrode according to claim 1 , wherein the product comprises a double-layer capacitor.
9. The method of manufacturing an electrode according to claim 1 , wherein the step of processing comprises heating a surface of at least one of the laminator rolls.
10. The method of manufacturing an electrode according to claim 1 , wherein the step of processing comprises heating surface of at least one of the laminator rolls to a temperature between about 100 degrees Celsius and about 300 degrees Celsius.
11. The method of manufacturing an electrode according to claim 1 , further comprising cooling the laminated electrode product.
12. The method of manufacturing an electrode according to claim 11 , wherein the step of cooling comprises S-wrapping the laminated electrode product on a pair of chilling rolls and cooling the chilling rolls using a liquid with a temperature of between about 18 and about 22 degrees Celsius.
13. The method of manufacturing an electrode according to claim 1 , wherein the rolls of the laminator apply pressure of between about 50 and about 1000 pounds per linear inch of width of the dry film to the current collector and the dry film.
14. The method of manufacturing an electrode according to claim 1 , wherein the rolls of the laminator apply pressure of between about 350 and about 650 pounds per linear inch of width of the dry film to the current collector and the dry film.
15. The method of manufacturing an electrode according to claim 1 , wherein the rolls of the laminator apply pressure of about 500 pounds per linear inch of width of the dry film to the current collector and the dry film.