Method of manufacturing an electrode or capacitor product
View Patent ↗A method of manufacturing an electrode product where 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. A method 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 and a second surface; coating the first surface with a first wet binder layer;
drying the first wet binder layer to result in a first dry binder layer coating the first surface;
providing a first film of active electrode material;
stacking the first film and the current collector so that the first dry binder layer is in contact with the first film; and
laminating the current collector and the first film by pressing the current collector and the first film to cause the first film to densify and to adhere to the first surface, thereby obtaining a laminated electrode product.
2. A method of manufacturing an electrode according to claim 1 , wherein the step of laminating is performed so that the first film is densified without spreading to an extent necessitating trimming.
3. A method of manufacturing an electrode according to claim 2 , further comprising:
coating the second surface with a second wet binder layer;
drying the second wet binder layer to result in a second dry binder layer coating the second surface;
providing a second film of active electrode material; and
stacking the second film and the current collector so that the second dry binder layer is in contact with the second film;
wherein the step of laminating further comprises pressing the second film and the current collector to cause the second film to adhere to the second surface, and the second film to be densified without spreading to an extent necessitating trimming.
4. A method of manufacturing an electrode according to claim 3 , 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 first film.
5. A method of manufacturing an electrode according to claim 3 , wherein the step of providing a current collector comprises providing a metal.
6. A method of manufacturing an electrode according to claim 3 , wherein the step of providing a current collector comprises providing a metal foil.
7. A method of manufacturing an electrode according to claim 6 , wherein laminating consists of a single pass through a laminator.
8. A method of manufacturing an electrode according to claim 6 , wherein the first and second films are not separately densified.
9. A method of manufacturing an electrode according to claim 6 , wherein the step of lamination does not cause the first and second films to spread beyond the current collector.
10. A method of manufacturing an electrode according to claim 6 , wherein the step of providing the first film comprises: mixing particles of active electrode material with a polymer and a conduction promoter to form a dry powder material; and fibrillizing the dry powder material using a dry high-shear technique.
11. A method of manufacturing an electrode according to claim 6 , wherein the step of lamination comprises heating the first film and the second film.
12. A method of manufacturing an electrode according to claim 6 , wherein the step of lamination comprises processing the first film, the second film, and the current collector between rolls of a laminator.
13. A method of manufacturing an electrode according to claim 12 , wherein the step of processing comprises heating surface of at least one of the laminator rolls.
14. A method of manufacturing an electrode according to claim 12 , wherein: the first binder layer and the second binder layer comprise a thermoplastic; and the step of processing comprises heating surfaces of at least one of the laminator rolls to a temperature sufficient to melt the thermoplastic of the first and second binder layers but insufficient to decompose the thermoplastic of the first and second binder layers.
15. A method of manufacturing an electrode according to claim 14 , wherein:
the first film, the second 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 combined thickness of the current collector, the first and second films, and the first and second binder layers is reduced by between about 30 and about 70 percent, the step of setting a gap being performed before the film and the current collector pass between the first and second laminator rolls.
16. A method of manufacturing an electrode according to claim 12 , wherein the step of processing comprises heating surfaces of at least two of the laminator rolls to a temperature between about 100 degrees Celsius and about 300 degrees Celsius.
17. A method of manufacturing an electrode according to claim 16 , wherein the step of providing a current collector comprises providing a material that does not stretch significantly.
18. A method of manufacturing an electrode according to claim 12 , wherein the rolls of the laminator apply pressure of between about 50 and about 1000 pounds per linear inch to the current collector and the first and second films.
19. A method of claim 1 , further comprising a step of winding the laminated current collector on a roll.
20. A method of manufacturing a capacitor product, the method comprising:
providing a current collector comprising a first surface;
providing an adhesive onto the first surface; and
drying the adhesive to form a dried adhesive on the current collector,
wherein after the step of drying the adhesive, the current collector is rolled onto a storage roll.