V Doped Nanostructured MnO ₂ Electrodes for Asymmetric Supercapacitors

Manganese dioxide (MnO 2 ) has emerged as a highly promising supercapacitor electrode material due to its high theoretical specific capacitance, low cost, and excellent capacity retention and stability stemming from its multiple redox states. However, its inherently low electrical conductivity severely limits rapid charge transport, resulting in practical capacities significantly below theoretical values. To overcome this problem, this study successfully grew vanadium(V)─doped MnO 2 composites on carbon cloth (CC) via a simple one-step hydrothermal method, achieving a mass loading as high as 11.5 mg/cm 2 . The introduction of V effectively modulates the nanoscale morphology and microstructure of MnO 2, converting the original nanonetwork into distinctive three-dimensional nanospheres structure. At a V doping concentration of 0.5 mmol, the prepared V 0.5 -MnO 2 /CC composite electrode exhibits outstanding electrochemical performance: a surface capacitance as high as 3.99 F/cm 2 at a current density of 1 mA/cm 2, coupled with exceptional cycling stability. The asymmetric supercapacitor (ASC) device achieved a high energy density of 0.5298 mWh/cm 2 at a power density of 1.5643 mW/cm 2 . This work offers a feasible route to construct high-loading and high-performance manganese-based electrodes via nanoscale cation doping engineering, which are well applicable to asymmetric supercapacitors serving wearable electronics and portable energy storage.