Carbon Nanotube-Supported Vanadium Substituted Phospho-Molybdate Nanohybrid for Supercapacitor Applications

Owing to the depletion of conventional energy sources, our civilization is slowly transitioning to renewables. Therefore, designing effective energy storage systems is one of the most pressing technical demands. The quest for improved energy and power densities in energy storage devices, particularly those with long cycle life, has pushed the investigation of novel materials intended to build effective supercapacitors. In this work, nanohybrid materials are synthesized using a hydrothermal technique by mixing carbon nanotubes and a polyoxometalate cluster, H₄[PVMo₁₁O₄₀].xH₂O. Henceforth, this complex is acronymed as CNT-PVMo₁₁. Further, electrochemical analysis of CNT-PVMo₁₁ nanohybrid is carried out to examine various characteristics of the supercapacitor cell made with this nanohybrid. The cyclic voltammetry confirms the diffusive-dominant charge-storage process, quantifying a 72.83% diffusion mechanism at a scan rate of 1 mV s^-1. The galvanostatic charge-discharge analysis of CNT-PVMo₁₁ nanohybrid material showed a specific capacitance of 229.35 F g^-1 with energy and power densities of 31.85 Wh kg^-1 and 2000 W kg^-1, respectively, at 1 A g^-1 current density. The electrode material also shows 90% capacitance retention even after 6000 cycles at 8 A g^-1 current density, indicating the material's remarkable stability. The high specific capacitance, excellent energy density, and impressive cycling stability of the hybrid material make it a promising candidate for next-generation supercapacitor electrodes.