Supercapacitor having a highly conductive graphene foam electrode

Abstract

A supercapacitor electrode comprising a solid graphene foam impregnated with a liquid or gel electrolyte, wherein the solid graphene foam is composed of multiple pores and pore walls, wherein pore walls contain a pristine graphene material having essentially zero % of non-carbon elements, or a non-pristine graphene material having 0.001% to 5% by weight of non-carbon elements wherein non-pristinegraphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, or a combination thereof, and the solid graphene foam, when measured in a dried state without electrolyte, has a physical density from 0.01 to 1.7 g / cm3, a specific surface area from 50 to 3,200 m2 / g, a thermal conductivity of at least 200 W / mK per unit of specific gravity, and / or an electrical conductivity no less than 2,000 S / cm per unit of specific gravity.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Patent Application No. 14 / 998,475, filed January 11, 2016, which is incorporated herein by reference. technical field [0003] The present invention relates generally to the field of supercapacitors, and more particularly to graphene foam based electrodes, supercapacitors containing such electrodes and methods of production thereof. Background technique [0004] A critical review of supercapacitors [0005] Electrochemical capacitors (ECs), also known as ultracapacitors or ultracapacitors, are being considered for use in hybrid electric vehicles (EVs), where they can supplement batteries used in electric vehicles to provide the power burst needed for rapid acceleration. However, the biggest technical hurdle is making battery-powered cars commercially viable. The battery will still be used for cruising, but the supercapacitor (with its ability to discharge energy more quickly tha...

AI Technical Summary

Problems solved by technology

[0011] (2) Although high gravimetric capacitance at the electrode level (based on active material weight alone) is often claimed in the published literature and patent documents, these electrodes unfortunately do not provide supercapacitor cell or component levels with high capacity of the energy storage device (based on total cell weight or component weight)

Furthermore, any electrode prepared in this way thicker than 50 μm is brittle and weak

There have been no effective solutions to these problems

There are several major problems associated with this method: (a) the high pressure requirement makes it an impractical method for industrial scale production

There are several problems associated with this approach: (a) catalytic CVD is inherently a very slow, highly energy-intensive, and expensive process; (b) etchant is typically a highly undesirable chemical and the resulting Ni-containing etching solution is a source of contamination

This method also has several disadvantages: (a) the method requires very tedious chemical treatment of both graphene oxide and PS particles

(b) Removal of PS by toluene also leads to a weakened macroporous structure

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