Two for One: A Biomass Strategy for Simultaneous Synthesis of MnO2 Microcubes and Porous Carbon Microcubes for High Performance Asymmetric Supercapacitors

The capacitive properties of asymmetric supercapacitors (ASCs) are inseparable from the development of anode and cathode materials, which usually require high accessible surface area and uniform porous distribution. Herein, a simple and economical "two for one" strategy is introduced for the simultaneous synthesis of microscale porous MnO2 microcubes (PMMs) and porous carbon microcubes (PCMs) derived from a single precursor cubic MnCO3/biocarbon (CM) which are prepared by natural agaric. Benefiting from a high specific surface area, delicate construction, and adequate mesoporous distribution, PCMs and PMMs could help to realize fast ion diffusion and easy ion accessibility. As expected, microscale PCM anode and PMM cathode materials exhibit superior capacitive performances, including high specific capacitance and impressive rate performance in a three-electrode system, respectively. Moreover, the assembled ASCs physical device PCM//PMM presents a high energy density (46.1 Wh kg–1 at 1.0 kW kg–1) and an excellent long-term cyclability (91% capacitance retention after 10 000 cycles at 1.0 A g–1). Therefore, the two-for-one strategy not only provided a simple and effective method to prepare high-performance electrode materials for ASCs, but also it is of great significance for natural biomass to achieve multidirectional applications and effectively replace commercial carbon sources from fossil fuels.