Li2C2O4 with 3D confinement as simultaneous sacrificial material and activation reagent of biomass-derived carbon for advanced lithium-ion capacitors

Inappropriate pore size distribution and the lack of a suitable lithium-cation source in the device are the key issues limiting the industrial application of biowaste carbon-based lithium-ion capacitors (LICs) to achieve both high energy density and power density for energy storage. Herein, the Li2O nanowires, decomposed from Li2C2O4 under three-dimensional confinement provided by wasted feather-derived carbon, are introduced as a sacrificial material for self-prelithiation activated carbon materials (prAC) cathode preparation with a high practical specific capacity of 1376 mAh/g. Accompanied by the in-situ formation of Li2O, the volume of mesopores increases significantly to 0.319 cm3/g (32.1 vol% of the total pore volume) by activation with CO2 yielded by the decomposition of Li2C2O4. The assembled prAC/graphite LIC demonstrates a high energy density of (122 Wh/kg at 220 W/kg) and a high power density (13 kW/kg at 30 Wh/kg), as well as a superior lifespan of 10,000 cycles at 1 A/g.