Biomass-Derived Carbon Electrodes for High-Performance Supercapacitors

Supercapacitors with the performance advantages of high-power density are emerging materials for energy storage/conversion systems that can combat climate change caused by CO2 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 degrees 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.

Automated summary

Supercapacitors with high-power density are emerging materials for energy storage and conversion systems. However, preparing high-performance electrodes with high mass loading is still a challenge. In this study, chitosan and active carbon (SSP-900) were combined to synthesize a high mass-loading freestanding electrode. The resulting C(1000)G(0.2) material exhibited outstanding electrochemical properties, including high specific mass capacitance and specific area capacitance. A symmetrical supercapacitor assembled with 12 mg mass loading showed large specific capacitance, high energy density, and capacitance stability. The distinguished electrochemical performance of freestanding electrodes has prospective applications in storing and converting electrical energy from intermittent solar and wind sources.