Carbon containing binderless electrode formation
An anode or negative electrode having a material matrix of carbon, graphene and an active element such as silicon or tin is described. The electrode is fabricated from an electrode slurry that does not utilize an organic binder. The electrode slurry comprises a combination of silicon and graphene oxide suspensions that is applied to a surface of a substrate such as a current collector. The layer of electrode slurry is heat treated to ensure adhesion of the layer of active electrode material to the surface of the current collector. The electrode may be incorporated within a lithium ion electrochemical cell.
1. An electrode, comprising:
a) a first active electrode material comprising graphene or graphene oxide, wherein at least a portion of the graphene or graphene oxide comprises defect pores formed by carbon vacancies;
b) a second active electrode material combined with the first active electrode material; and
c) a non-active material portion comprising carbon, wherein the electrode contains no binder residue.
2. The electrode of claim 1 wherein the second active electrode material is selected from the group consisting of silicon, silicon oxide, tin, tin oxide, antimony, aluminum, silver, germanium, gallium, magnesium, zinc, lead, bismuth, carbon, titanium oxide, lithium titanium oxide, and combinations thereof.
3. The electrode of claim 1 wherein the first active electrode material comprises from about 28 weight percent to about 70 weight percent of the electrode composition, the second active electrode material comprises from about 30 weight percent to about 70 weight percent of the electrode composition, and the non-active material portion comprises the remainder.
4. The electrode of claim 1 wherein the non-active carbon material comprises amorphous carbon.
5. The electrode of claim 1 further comprising a porosity of 40 percent or less.
6. The electrode of claim 1 wherein the first active electrode material comprises a particle size that ranges from about 0.5 μm to about 5 μm.
7. The electrode of claim 6 wherein the first active electrode material comprises a particle size that ranges from about 5 μm to about 25 μm.
8. A method of fabricating an electrode, comprising:
providing a substrate having a surface;
providing an electrode slurry comprising a first active electrode material comprising graphene or graphene oxide, wherein at least a portion of the graphene or graphene oxide comprises defect pores formed by carbon vacancies, a second active electrode material, a dispersant and a first solvent; and
applying the electrode slurry to the substrate surface.
9. The method of claim 8 wherein the second active electrode material is selected from the group consisting of silicon, silicon oxide, tin, tin oxide, antimony, aluminum, silver, germanium, gallium, magnesium, zinc, lead, bismuth, carbon, titanium oxide, lithium titanium oxide, and combinations thereof.
10. The method of claim 8 including forming the electrode having a porosity of 40 percent or less.
11. The method of claim 8 wherein the dispersant is selected from the group consisting of glycol ethers, block copolymers derived from ethylene oxide and propylene oxide, acetylenic diols, sodium dodecanoate, alkanolamide, lanolin, polyvinylpyrrolidone, sodium alkyl sulfate, sodium alkyl sulfonate, lecithin, polyacrylate, sodium silicate, polyethoxy, and combinations thereof.
12. The method of claim 8 wherein the first solvent is selected from the group consisting of a polar aprotic solvent, water, ethanol, isopropyl alcohol, ethyl acetate, ethylene glycol, N-methylolpyrrolidone, and combinations thereof.
13. The method of claim 8 including applying a primer coat comprised of an adhesive agent prior to applying the electrode slurry.
14. The method of claim 13 wherein the adhesive agent is selected from the group consisting of titanium chelates, titanium phosphate complexes, butyl titanium phosphate, titanate esters, diisopropoxy titanium bis(ethyl-3-oxobutanoate, isopropoxy titanium acetylacetonate, polyvinylpyrrolidone, nitrocellulose and combinations thereof.
15. The method of claim 8 further comprising: mixing the first active electrode material with the first solvent thereby forming a first active electrode material suspension; combining the second active electrode material with the first active electrode material suspension; and combining a dispersant solution mixture comprising the dispersant and a second solvent with the first active electrode material suspension to form the electrode slurry.
16. The method of claim 15 wherein the first active electrode material suspension comprises from about 0.5 weight percent to about 2.5 weight percent graphene oxide, the remainder comprising the first solvent; and wherein the dispersant solution mixture comprises from about 3 weight percent to about 6 weight dispersant, the remainder comprising the second solvent.
17. The method of claim 15 wherein at least one of the first and second solvents is selected from the group consisting of a polar aprotic solvent, water, ethanol, isopropyl alcohol, ethyl acetate, ethylene glycol, N-methylolpyrrolidone, and combinations thereof.
18. The method of claim 8 further comprising heat treating the electrode slurry coated substrate at a temperature ranging from about 600° C. to about 800° C.
19. The method of claim 8 further comprising vacuum filtering the electrode slurry prior to applying the electrode slurry to the substrate surface.
20. An electrochemical cell, comprising:
a) a negative electrode comprising:
i) a first active electrode material comprising graphene or graphene oxide, wherein at least a portion of the graphene or graphene oxide comprises defect pores formed by carbon vacancies;
ii) a second active electrode material combined with the first active electrode material;
iii) a non-active material portion comprising carbon; and
iv) wherein the negative electrode contains no binder residue;
b) a positive electrode comprising a positive active electrode material having a lithium constituent; and
c) an ionically conductive electrolyte solution.
21. The electrochemical cell of claim 20 wherein the second active electrode material is selected from the group consisting of silicon, silicon oxide, tin, tin oxide, antimony, aluminum, silver, germanium, gallium, magnesium, zinc, lead, bismuth, carbon, titanium oxide, lithium titanium oxide, and combinations thereof.
22. The electrochemical cell of claim 20 wherein the first active electrode material comprises from about 28 weight percent to about 70 weight percent of the electrode composition, the second active electrode material comprises from about 30 weight percent to about 70 weight percent of the electrode composition, and the non-active material portion comprises the remainder.
23. The electrochemical cell of claim 20 wherein the negative electrode comprises a porosity of 40 percent or less.
24. The electrochemical cell of claim 20 wherein the cell is capable of exhibiting at least about 500 mAh/cc.