Biomass‐Derived Carbon Electrodes for High‐Performance Supercapacitors

Abstract Supercapacitors with the performance advantages of high‐power density are emerging materials for energy storage/conversion systems that can combat climate change caused by CO 2 emissions and are of importance with the development of electronic products and artificial intelligence. But rationally preparing high‐performance electrode with high mass‐loading quantity remains challenge. Herein, we have opted for chitosan as well‐structured binding agent to combine with active carbon (SSP‐900), a 3D hierarchical micro‐meso‐macro porous biochar previously obtained, to synthesize high mass‐loading freestanding electrode. Especially, the freestanding material (C 1000 G 0.2 ), owning 0.2 g SSP‐900 and suffering carbonization at 1000 °C exhibits high specific surface area of 389.3 cm 2 g −1 , and self‐doped N, O (2.75 %, 5.64 %). That awards C 1000 G 0.2 outstanding electrochemical properties, including high specific mass capacitance of 199.2 F g −1 , splendid specific area capacitance of 4.37 F cm −2 in 21.93 g cm −2 , which is more competitive than conventional freestanding materials. Symmetrical supercapacitor with mass loading of 12 mg is assembled and exhibits large specific capacitance of 65 F g −1 , high energy density of 32.5 Wh kg −1 under the power density of 90.4 W kg −1 , and capacitance stability of 98 % after 10,000 cycles. The distinguished electrochemical performance of freestanding electrodes supplies prospective application for storing/converting electrical energy from intermittent solar and wind.