MnO₂ and biomass-derived 3D porous carbon composites electrodes for high performance supercapacitor applications

MnO₂/biomass-derived porous carbon (BPC) composites have been prepared by a hydrothermal method, in which the BPC 3D porous carbon structure was based on a banana peel. The banana peel, after freeze drying, can maintain its hierarchical natural porous structure, which provides enough growth space for MnO₂ and reduces the agglomeration of MnO₂ particles. The MnO₂/BPC composites were characterized by XRD, FT-IR, XPS, TGA, SEM, TEM, BET. The electrochemical performance of the composites was tested in three-electrode supercapacitors using 1 M Na₂SO₄ aqueous solution as an electrolyte. Due to the large amounts of hierarchical pores and large pore volume, the as-prepared composites exhibited good electrochemical performance. Electrochemical measurements indicated that the MnO₂/BPC composites applied in supercapacitors had a specific capacitance of 139.6 F g⁻¹ at 300 mA g⁻¹, and exhibited a good cycling stability with a capacitance retention ratio of 92.3% after 1000 cycles (at 1 A g⁻¹). The MnO₂/BPC composites with 3D porous structure are promising materials in the application of supercapacitors.