Carbon Paper as Current Collectors in Graphene Hydrogel Electrodes for High-Performance Supercapacitors.

Current collectors are an important component of electrodes, functioning as conductive media by collecting currents from active materials and then exporting them to the external circuit. Common current collectors for graphene hydrogel (GH)-based supercapacitors are nickel foams or metal foils (platinum, gold, and aluminium, etc.). Here, hydrothermally synthesized GH was directly pressed on carbon paper and used as electrodes (denoted as GHE) for supercapacitors. With a mass loading of 2.7 mg·cm at an active area of 0.64 cm, the GHE-based supercapacitors revealed a high gravimetric capacitance of 294 F·g at a current density of 1.18 A·g. When increasing the current density to 28.24 A·g, 66% (193 F·g) of the initial capacitance was maintained for the GHE-based supercapacitors. High performance for GHE-based supercapacitors was attributed to large specific surface area and good electrical conductivity of GH, and its intimate contact with carbon paper.