3-Dimensional porous carbon derived from waste aucklandia lappa straw for high-performance liquid and all-solid-state supercapacitors

Efficient and sustainable biochar as electrode material is the key to constructing portably green energy storage equipment. Using waste aucklandia lappa straw as carbon precursor, biomass porous carbon was prepared by high temperature carbonization and KOH activation. The 3-dimensional porous carbon material was obtained by optimizing the proportion of activator, which has a high specific surface area (2427 m2 g−1), abundant pore structure and substantially high specific capacitance (up to 431.35 F g−1 at 0.5 A g−1). The assembled symmetrical supercapacitor exhibits a wide voltage range of 0–2.0 V and a high energy density of 36.51 Wh kg−1 in 1 M Na2SO4 electrolyte. The all-solid-state supercapacitor with PVA/KOH gel as electrolyte has high response frequency and phase angle, which can provide high specific capacitance of 340.98 F g−1 and energy density of 19.59 Wh kg−1 at 0.5 A g−1. The capacitance retention rate is 89.47% after 10,000 cycles. Aucklandia lappa straw-derived porous carbon electrode material is an ideal candidate for the preparation of high-performance supercapacitor.