A high-performance supercapacitor electrode based on Zn/V co-doped NiMoO4: a cation–cation doping strategy

Abstract

Rational design of electrode materials with tailored structural and electronic properties is crucial for the development of high-performance supercapacitors. Here, we report a Zn/V co-doping strategy for NiMoO₄ (ZV-NM), which simultaneously induces abundant oxygen vacancies and a phase transformation from the α to the β phase. The synergistic effects of lattice distortion, enhanced redox activity, and improved electrical conductivity collectively endow ZV-NM3 with extraordinary charge storage capabilities, achieving a remarkable specific capacitance of 1423.1 F g⁻¹ (316.24 mA h g⁻¹) at a current density of 0.4 A g⁻¹. When integrated into an asymmetric supercapacitor device (ZV-NM3/NF//GS), this optimized electrode exhibits a specific capacitance of 101 F g⁻¹ at a current density of 0.4 A g⁻¹. It offers a high energy density of 45.4 Wh kg⁻¹ and a power density of 1.31 kW kg⁻¹, while retaining 90.45% of its capacitance after 10 000 charge/discharge cycles. These results highlight the effectiveness of binary doping in engineering vacancy-rich, phase-optimized transition metal oxides for next-generation energy storage applications.