Enhanced electrochemical performance of battery-type Zn-doped MoO₃ nanoflakes for hybrid supercapacitor applications

Transition metal oxides have emerged as promising candidates for electrochemical energy storage devices, such as batteries and supercapacitors, due to their versatile redox properties. However, challenges related to low energy density and limited cycling stability remain. In this study, MoO₃ (MO) and zinc (Zn)-MoO3 (Zn-MO) nanoflakes were successfully synthesized via a hydrothermal method. The Zn-MO nanoflakes exhibited significantly enhanced electrochemical performance compared to pristine MO, achieving a high specific capacity of 82.7 mAh g⁻¹ and a capacitance of 647.8 F g⁻¹ at a current density of 2 A g⁻¹. Remarkably, after 10,000 charge–discharge cycles, the Zn-MO electrode retained 98% of its initial capacity with 99% coulombic efficiency. Furthermore, a pouch-type hybrid supercapacitor (HSC) was assembled using Zn-MO and activated carbon, delivering an energy density of 26.07 Wh kg⁻¹ and a power density of 5120 W kg⁻¹. The device demonstrated excellent cycling stability (90%) and high coulombic efficiency (99%), highlighting its practical applicability for real-world energy storage applications.