Nickel‐Doped Tungsten Oxide Cathode for High‐Performance Asymmetric Supercapacitors

ABSTRACT

Hydrothermally synthesized Ni‐doped WO ₃ was developed as a high‐performance electrode material for supercapacitor applications. The successful incorporation of Ni into the WO ₃ lattice and its influence on the structural, morphological, surface chemical, and electrochemical properties were systematically investigated. Ni doping effectively improved the charge‐storage behavior of WO ₃ , delivering a high specific capacitance of 1580 F g ⁻¹ at 2 A g ⁻¹ . The enhanced electrochemical performance is attributed to the favorable modification of the WO ₃ structure and electronic properties induced by Ni incorporation, which promotes efficient charge‐transfer and ion‐storage processes. To demonstrate its practical applicability, an asymmetric supercapacitor (ASC) was fabricated using Ni‐doped WO ₃ as the positive electrode and reduced graphene oxide (rGO) as the negative electrode. The assembled device achieved a maximum energy density of 10 Wh kg ⁻¹ and a maximum power density of 1700 W kg ⁻¹ , demonstrating a favorable energy–power balance. Moreover, the Ni‐doped WO ₃ electrode exhibited excellent cycling stability, retaining 98% of its initial capacitance after 5000 charge–discharge cycles. The series‐connected device successfully illuminated a red LED at 1.8 V, further demonstrating the practical potential of Ni‐doped WO ₃ for advanced energy‐storage applications.