A manganese oxide/biomass porous carbon composite for high-performance supercapacitor electrodes

Supercapacitors are an excellent energy storage device with broad application prospects in the new energy market. However, the low energy density of carbon-based materials severely limits their commercialization. In this study, a manganese oxide/biomass porous carbon composite with high energy density was prepared from soybean straw by the strategy of KOH activation to form porous structure and hydrothermal method to introduce manganese oxides as pseudocapacitors. The prepared composite possesses a high specific capacitance of 482 F g–1 at a current density of 0.5 A g–1. In addition, the supercapacitors assembled with the composite as electrode sheets have an energy density of up to 14.5 Wh kg–1 at a power density of 250 W kg–1. And the supercapacitors enable the light-emitting diode emit light continuously for 40 s. The successful preparation of the manganese oxide/biomass porous carbon composite provides a feasible method for the design and synthesis of high-performance supercapacitor electrode materials.