MnO2 nanowires anchored on biomass-derived porous carbon for enhanced supercapacitive performance

Incorporation of pseudocapacitive materials into porous carbon is a promising strategy to boost electrochemical performance. Herein, composite of biomass-derived porous carbon and MnO₂ (a typical pseudocapacitive material) was facilely fabricated through an in-situ synthesis approach with sorghum seeds derived porous carbon (SSC) as the skeleton for MnO₂ deposition. The as-prepared composite (MnO₂@SSC) exhibits hierarchical porous structure with abundant interlaced MnO₂ nanowires wrapping on the surface. While the porous structure is beneficial to the active sites exposure and electrolyte ions transport, the interlaced three-dimensional (3D) network of MnO₂ nanowires significantly boosts the tolerance toward volume shrinkage/expansion during the cyclic process. Consequently, the MnO₂@SSC-based electrode delivered quite promising supercapacitive performance including superior specific capacitance of 482.7 F/g at 0.5 A/g, outstanding long-term cycling stability (95.8% specific capacitance retention after 20,000 cycles) and high energy density of 13.7 Wh/kg at power density of 298.1 W/kg. Furthermore, all-solid-state flexible supercapacitor based on MnO₂@SSC can be facilely bent to various angles (0° to 150°) without significant degradation in the capacitive performance. This study provides a facile, cost-effective, and sustainable approach for the fabrication of high-performance electrode materials.