High-performance solid-state supercapacitors and microsupercapacitors derived from printable graphene inks
Solid-state supercapacitors and microsupercapacitors comprising printed graphene electrodes and related methods of preparation.
1. A method of fabricating a graphene capacitor, said method comprising:
providing a graphene ink composition comprising graphene, an ethyl cellulose and an ink solvent, said graphene ink composition not prepared from graphene oxide, wherein said ink solvent comprises 80:15:5 v/v cyclohexanone, terpineol and di(ethylene glycol) methyl ether;
depositing said graphene ink composition on a substrate;
annealing said graphene ink composition to decompose said ethyl cellulose and provide an electrode component comprising graphene; and
coupling an electrolyte and a metallic lead component to said electrode component, to provide said graphene capacitor,
wherein said capacitor is absent a separate current collector component.
2. The method of claim 1 wherein said deposition comprises inkjet printing said graphene ink composition on said substrate, to provide a microsupercapacitor.
3. The method of claim 1 wherein said deposition is selected from blade coating and spin coating said graphene ink composition on said substrate.
4. The method of claim 1 wherein two said capacitors are in a sandwich configuration to provide a supercapacitor such that two said electrode components, two said electrolytes and two said metallic lead components are positioned between two said substrates.
5. The method of claim 1 wherein said electrolyte is dried to provide an all solid-state capacitor.
6. The method of claim 1 wherein said deposition is on a flexible polymeric substrate.
7. The method of claim 1 wherein said provision of said ink composition comprises:
exfoliating a graphene source material with a medium comprising an organic solvent at least partially miscible with water, and an ethyl cellulose dispersing agent at least partially soluble in said organic solvent;
contacting at least a portion of said exfoliated graphene medium with an aqueous medium to concentrate exfoliated graphene in a solid composition comprising graphene and said ethyl cellulose;
isolating said solid composition from said media; and
contacting said solid composition with said ink solvent.
8. The method of claim 1 wherein a plurality of said capacitors are arranged in a configuration selected from series and parallel configurations.
9. The method of claim 1 wherein said annealing said graphene ink composition is performed at 350° C. for 4 hours.