Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells
Electrodes and methods of forming electrodes are described herein. The electrode can be an electrode of an electrochemical cell or battery. The electrode includes a current collector and a film in electrical communication with the current collector. The film may include a carbon phase that holds the film together. The electrode further includes an electrode attachment substance that adheres the film to the current collector.
1. An electrode comprising:
a current collector;
a monolithic self-supporting film in electrical communication with the current collector, the film comprising pyrolyzed carbon that holds the film together; and
an electrode attachment substance that adheres the film to the current collector, wherein the film comprises porosity and at least about 60 percent of the porosity is substantially free of the electrode attachment substance.
2. The electrode of claim 1 , wherein the electrode attachment substance is substantially electrically nonconductive.
3. The electrode of claim 1 , wherein the electrode attachment substance forms a substantially uniform layer disposed substantially over an entire surface of the film.
4. The electrode of claim 1 , wherein the electrode attachment substance comprises a polymer not soluble in a nonaqueous electrolyte solution.
5. The electrode of claim 4 , wherein the nonaqueous electrolyte solution comprises a carbonate solvent.
6. The electrode of claim 4 , wherein the polymer comprises polyacrylic acid, carboxymethyl cellulose, styrene butadiene rubber polyamideimide, polyvinylidene fluoride, polyethylene, or polypropylene.
7. The electrode of claim 1 , wherein the current collector comprises copper.
8. The electrode of claim 1 , further comprising a second electrode attachment substance sandwiched between the current collector and a second film in electrical communication with the current collector.
9. The electrode of claim 1 , wherein the film comprises an anode.
10. The electrode of claim 9 , wherein the anode comprises silicon.
11. The electrode of claim 1 , wherein the porosity comprises about 5 to about 50 percent by volume of the film.
12. The electrode of claim 1 , wherein the porosity comprises about 1 to about 70 percent by volume of the film.
13. The electrode of claim 1 , wherein the film comprises surfaces that are substantially free of the electrode attachment substance.
14. A method of forming the electrode of claim 1 comprising:
providing the current collector coated with a first electrode attachment substance on a first side of the current collector, wherein the first electrode attachment substance is in a substantially solid state;
placing a first monolithic self-supporting film comprising electrochemically active material on the first electrode attachment substance; and
heating the first electrode attachment substance to adhere the first monolithic self-supporting film to the current collector.
15. The method of claim 14 , further comprising:
providing a second electrode attachment substance on a second side of the current collector, wherein the second electrode attachment substance is in a substantially solid state.
16. The method of claim 15 , further comprising:
placing a second monolithic self-supporting film comprising electrochemically active material on the second electrode attachment substance.
17. The method of claim 16 , further comprising:
heating the second electrode attachment substance to adhere the second monolithic self-supporting film to the current collector.
18. The method of claim 17 , wherein heating the first electrode attachment substance and heating the second electrode attachment substance occur simultaneously.
19. The method of claim 14 , wherein providing the current collector comprises:
coating the current collector with a polymer solution on the first side of the current collector; and
drying the polymer solution to form the first electrode attachment substance.
20. The method of claim 15 , wherein providing a second electrode attachment substance comprises:
coating the current collector with a polymer solution on the second side of the current collector; and
drying the polymer solution to form the second electrode attachment substance.
21. The method of claim 14 , wherein providing the current collector comprises:
providing a polymer resin on the first side of the current collector; and
extrusion coating the polymer resin to form the first electrode attachment substance.
22. The method of claim 15 , wherein providing a second electrode attachment substance comprises:
providing a polymer resin on the second side of the current collector; and
extrusion coating the polymer resin to form the second electrode attachment substance.
23. The method of claim 14 , wherein the first electrode attachment substance comprises a polymer that is not soluble in a nonaqueous electrolyte solution.
24. The method of claim 23 , wherein the nonaqueous electrolyte solution comprises a carbonate solvent.
25. The method of claim 23 , wherein the polymer comprises polyacrylic acid, carboxymethyl cellulose, styrene butadiene rubber, polyamideimide, polyvinylidene fluoride, polyethylene, or polypropylene.
26. The method of claim 14 , wherein heating comprises heat laminating.
27. The method of claim 14 , wherein heating comprises roll pressing or flat pressing.
28. The electrode of claim 1 , wherein at least about 70 percent of the porosity is substantially free of the electrode attachment substance.
29. The electrode of claim 28 , wherein at least about 80 percent of the porosity is substantially free of the electrode attachment substance.
30. The electrode of claim 29 , wherein at least about 90 percent of the porosity is substantially free of the electrode attachment substance.
31. The electrode of claim 3 , wherein portions of the film penetrate the layer of the electrode attachment substance and come in direct contact with the current collector.
32. The electrode of claim 1 , wherein the pyrolyzed carbon comprises hard carbon.