Compositions and methods for dry electrode films having reduced binder content
Materials and methods for preparing dry cathode electrode film including reduced binder content are described. The cathode electrode film may be a self-supporting film including a single binder. The binder loading may be 3 weight % or less. In a first aspect, a method for preparing a dry free standing electrode film for an energy storage device is provided, comprising nondestructively mixing a cathode active material, a porous carbon, and optionally a conductive carbon to form an active material mixture, adding a single fibrillizable binder to the active material mixture, nondestructively mixing to form an electrode film mixture, and calendering the electrode film mixture to form a free standing electrode film.
1. An energy storage device, comprising:
an electrode comprising a dry electrode film in contact with a current collector, wherein the dry electrode film comprises:
about 90 wt. % to about 99 wt. % of a dry active material; and
at most 2 wt. % of a dry binder, wherein the dry electrode film is free-standing; and
wherein the energy storage device is configured to have a first cycle device efficiency of about 90% to about 94%.
2. The energy storage device of claim 1 , wherein the dry electrode film comprises about 95 wt. % to about 98 wt. % of the dry active material.
3. The energy storage device of claim 1 , wherein the dry active material comprises dry active material particles with a D 50 particle size of at least about 10 μm.
4. The energy storage device of claim 3 , wherein the dry active material particles have a D 50 particle size of about 10 μm to about 20 μm.
5. The energy storage device of claim 1 , wherein the dry active material is selected from at least one of a metal oxide, metal sulfide, a sulfur-carbon composite, a lithium metal oxide and a material including sulfur.
6. The energy storage device of claim 1 , wherein the electrode film comprises about 1 wt. % to 2 wt. % of a dry binder.
7. The energy storage device of claim 1 , wherein the dry binder consists essentially of a single dry binder.
8. The energy storage device of claim 1 , wherein the dry binder comprises a dry fibrillizable binder.
9. The energy storage device of claim 8 , wherein the dry fibrillizable binder comprises polytetrafluoroethylene (PTFE).
10. The energy storage device of claim 1 , wherein the dry electrode film further comprises a porous carbon material.
11. The energy storage device of claim 10 , wherein the dry electrode film comprises at most about 8 wt. % of the porous carbon material.
12. The energy storage device of claim 10 , wherein the dry electrode film comprises about 1 wt. % to about 7 wt. % of the porous carbon material.
13. The energy storage device of claim 10 , wherein the porous carbon material comprises activated carbon.
14. The energy storage device of claim 1 , wherein the dry electrode film further comprises a conductive additive.
15. The energy storage device of claim 14 , wherein the dry electrode film comprises at most about 5 wt. % of the conductive additive.
16. The energy storage device of claim 14 , wherein the conductive additive comprises a conductive carbon material.
17. The energy storage device of claim 16 , wherein the conductive carbon material comprises carbon black.
18. The energy storage device of claim 1 , wherein the energy storage device is a battery.
19. A method of fabricating the energy storage device of claim 1 , comprising:
mixing the dry active material with the dry binder to form a dry electrode film mixture;
calendering the dry electrode film mixture to form the dry electrode film;
disposing the dry electrode film onto the current collector to form the electrode; and
disposing the electrode in a housing to form the energy storage device.
20. The method of claim 19 , wherein calendering the dry electrode film mixture comprises at most three passes through a calender.
21. The method of claim 19 , further comprising mixing the dry active material with a porous carbon material to form a dry active material mixture, wherein mixing the dry active material with the dry binder comprises mixing the dry active material mixture with the dry binder.
22. The method of claim 21 , wherein at least one of the mixing of the dry active material and the porous carbon material and the mixing of the dry active material mixture with a dry binder is performed by a non-destructive mixing process.
23. The method of claim 22 , wherein the non-destructive mixing process is a resonant acoustic mixing process.
24. The method of claim 22 , wherein the non-destructive mixing process is performed by a blade type mixer with a tip speed of about 10 meters/min to about 40 meters/min.
25. The method of claim 21 , wherein at least one of the mixing of the dry active material and the porous carbon material and the mixing of the dry active material mixture with a dry binder is performed by a high shear process.
26. The method of claim 25 , wherein the high shear process comprises a jet milling process.