Sustainable activated carbon fibers from liquefied wood with controllable porosity for high-performance supercapacitors

Activated carbons are regarded as the most important electrode materials for commercial supercapacitors because of their low cost, high surface area, and good electrical conductivity. The environmentally friendly, low-cost and renewable biomass is a promising raw material for the high-performance carbon electrode material. Herein, a series of activated carbon fibers (ACFs) are fabricated by one-step carbonization and activation of wood-derived fibers with different activation times. The micropore surface area, mesopore/micropore ratio and pore size of the ACE series are successfully controlled by adjusting the levels of burn-off in order to study the effects of these parameters on specific capacitance and rate capability. Electrochemical measurements show that the electrochemical performance of the ACF series increases with the progress of gasification unless excessive burn-off occurs. The sample with optimal structure exhibits an outstanding specific capacitance of 280 F g(-1) at 0.5 A g(-1) and excellent rate capability (81.8% capacitance retention at 10 A g(-1)) in 1 M H2SO4. Furthermore, it demonstrates good cyclic stability, showing a high capacitance retention of 99.3% over 2000 charge-discharge cycles. The excellent electrochemical performance of this sample is attributed to the large micropore surface area, a proportion of mesopores in the range of 3-4 nm, good electrical conductivity and fast charge transfer.