Unravelling the Polymorph Dependant Electrochemical Behavior of VO₂ for Advanced Supercapacitor Applications

The development of sustainable, high‐performance electrode materials is essential for scalable energy storage devices. A key challenge lies in developing cost‐effective systems that combine high energy and power densities. Vanadium dioxide (VO 2 ) with its remarkable pseudo‐capacitive behavior emerges as a promising candidate owing to its polymorphic forms and unique phase transition property. Herein, VO 2 polymorphs (A, B, D, and M) are hydrothermally synthesized and systematically investigated. Among them, VO 2 (M) micro‐rods exhibited a superior electrochemical performance, delivering a specific capacitance of 150 F g −1 at 1 A g −1 current density and demonstrating 99% of capacitive contribution at 40 mV s −1 , as confirmed by kinetic studies. Furthermore, an asymmetric hybrid supercapacitor employing VO 2 (M) micro‐rods as the positive electrode and Ti 3 C 2 T x MXene as the negative electrode achieved remarkable energy storage performance, delivering a specific capacitance of 92.8 F g −1 at 2 A g −1 . The device delivered a maximum energy density of 68.18 Wh kg −1 and power density of 2298.2 W kg −1 , while maintaining 100% capacitive retention and coulombic efficiency over 5000 cycles. The high capacitive contribution observed in both pristine VO 2 (M) and the asymmetric VO 2 (M)//Ti 3 C 2 system highlights their potential as a promising electrode material for the next generation energy storage technologies.