Core–shell composite of wood-derived biochar supported MnO2 nanosheets for supercapacitor applications

Abstract

Eco-friendly wood-derived biochar (WDB) was used as a substrate material to support sheet-like nano-MnO₂ via an easily-operated in situ redox reaction between the biochar and KMnO₄. WDB was readily obtained by pyrolyzing wood waste of agriculture and industry. The MnO₂/WDB composite displays a core–shell structure and can be utilized as a free-standing and binder-free supercapacitor electrode. The MnO₂/WDB electrode has a moderate specific capacitance of 101 F g⁻¹, an excellent coulombic efficiency of 98–100%, and a good cyclic stability with a capacitance retention of 85.0% after 10 000 cycles, making it useful for supercapacitor applications. Moreover, it is expected that such porous inexpensive WDB can serve as a novel harmless substrate material to combine with other electrochemical active substances for the development of high-performance energy storage devices.