Porous layer-stacking carbon derived from in-built template in biomass for high volumetric performance supercapacitors.

Two-dimensional (2D)porous graphene-based materials such as graphene nanomesh, activated graphene and curved graphene, possess high gravimetric performances due to their high surface area and short ion transport path. However, their poor volumetric performances come from low density and/or high pore volume of the electrode materials, as well as their high manufacturing cost, which would limit their further applications. In this work, densely porous graphene-like carbon (PGC)materials were greenly synthesized through hydrothermal treatment of fungus (Auricularia)and subsequent carbonization process. Layer-stacking PGC derived from cell walls of fungus has high surface area (1103 m2 g?1), high bulk density (about 0.96 g cm?3), and hierarchically interconnected porous framework, which can provide more storage sites and short transport paths for electrolyte ions, and enhance the overall conductivity of the electrode. As a result, the PGC electrode shows ultra-high volumetric capacitance of 360 F cm?3 and excellent cycling stability with 99 per cent capacitance retention after 10000 cycles. More importantly, the as-assembled symmetric supercapacitor delivers superior volumetric energy density of 21 Wh L?1 and excellent cycling stability (96 per cent specific capacitance retention after 10000 cycles). These exciting results suggest a low-cost and environmentally friendly design of electrode materials for high volumetric-performance supercapacitors.