Large-format battery anodes comprising silicon particles
Large-scale anodes containing high weight percentages of silicon suitable for use in lithium-ion energy storage devices and batteries, and methods of manufacturing the same, are described. The anode material described herein can include a film cast on a current collector substrate, with the film including a plurality of active material particles and a conductive polymer membrane coated over the active material particles. In some embodiments, the conductive polymer membrane comprises polyacrylonitrile (PAN). The method of manufacturing the anode material can include preparation of a slurry including the active material particles and the conductive polymer material, casting the slurry on a current collector substrate, and subjecting the composite material to drying and heat treatments.
1. An anode comprising:
a current collector substrate with a surface roughness R z of greater than 1.5 micrometers, and wherein a magnitude of an arithmetical mean height Sa of the current collector substrate is less than three times a developed interfacial ratio Sdr of the current collector substrate; and
a film disposed over the current collector substrate, wherein the film comprises:
a plurality of active material particles; and
a conductive polymer membrane coating disposed over the active material particles, the conductive polymer membrane coating comprising a thermoplastic polymer treated to become a cyclized, non-plastic ladder compound.
2. The anode of claim 1 , wherein the film comprises a thickness of 10 to 80 micrometers.
3. The anode of claim 1 , wherein the plurality of active material particles is selected from the group consisting of silicon, hard-carbon, graphite, graphene, germanium, titanium oxide, tin, magnesium, antimony, lead, and combinations thereof.
4. The anode of claim 1 , wherein the plurality of active material particles comprise particles selected from the group consisting of silicon particles, a silicon-carbon composite material particles, and combinations thereof.
5. The anode of claim 4 , wherein the particles are selected from the group consisting of nano-sphere silicon, nano-wire silicon, nano-rod silicon, whiskers, “coral-shaped” silicon, micro-spherical silicon, silicon-graphite, silicon-graphene, silicon-hard carbon, and combinations thereof.
6. The anode of claim 4 , wherein the film comprises 30-60 wt. % silicon particles.
7. The anode of claim 4 , wherein the film comprises greater than or equal to 60 wt. % silicon particles.
8. The anode of claim 1 , wherein the thermoplastic polymer treated to become the cyclized, non-plastic ladder compound is selected from the group consisting of polyacrylonitrile (PAN), poly(acrylic acid) (PAA), carboxymethyl cellulose (CMC), alginate and combinations thereof.
9. The anode of claim 8 , wherein the thermoplastic polymer treated to become the cyclized, non-plastic ladder compound comprises polyacrylonitrile (PAN).
10. The anode of claim 1 , wherein a porosity of the film is between 50-70%.
11. An energy storage device comprising:
the anode of claim 1 ;
a cathode; and
an electrolyte.
12. The energy storage device of claim 11 , wherein the electrolyte comprises an imide-based room temperature ionic liquid.
13. The anode of claim 1 , wherein the magnitude of the arithmetical mean height Sa of the current collector substrate is about the same as the developed interfacial ratio Sdr of the current collector substrate.
14. A method of making an anode comprising:
combining an active material, an additive powder, a polymer powder, and a solvent capable of dissolving the polymer powder to form a slurry, wherein the polymer powder comprises a thermoplastic polymer treated to become a cyclized, non-plastic ladder compound;
casting the slurry over a current collector substrate to form a cast film, wherein the current collector substrate comprises a surface roughness R z of greater than 1.5 micrometers, and wherein a magnitude of an arithmetical mean height Sa of the current collector substrate is less than three times a developed interfacial ratio Sdr of the current collector substrate;
drying the cast film; and
heat treating the cast film.
15. The method of claim 14 , wherein the dried and heat treated cast film has a thickness of 10 to 80 micrometers.
16. The method of claim 14 , wherein the heat treatment comprises applying heat to the cast film at temperatures of 200 to 400° C. for a time of 1 to 12 hours.
17. The method of claim 16 , wherein the heat treatment is completed under vacuum or inert gas flow.
18. The method of claim 14 , wherein the slurry has a Brookfield viscosity of 2000-6000 cP at 20 to 100 RPM using a #64 spindle, at room temperature.
19. The method of claim 14 , wherein the active material comprises silicon and a carbonaceous active material.
20. The method of claim 19 , wherein a weight ratio of silicon:carbonaceous material is 10:90 to 90:10.
21. The method of claim 19 , wherein a weight ratio of silicon:carbonaceous material:polymer powder is 30:55:15.
22. The method of claim 14 , wherein the additive powder comprises a material selected from the group consisting of a lithium metal powder, a lithium nitride, an oxalic acid, and combinations thereof.
23. The method of claim 14 , wherein the solvent is selected from the group consisting of N,N-dimethylformamide (DMF), dimethyl sulfone (DMSO 2 ), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethyl acetamide (DMAc), ethylene carbonate (EC), propylene carbonate (PC), and combinations thereof.
24. A method of making an energy storage device comprising:
manufacturing the anode according to the method of claim 14 ;
disposing the anode, a cathode and an electrolyte within a housing.