Synthesis and applications of self-supported porous polymetallic tungstates heterostructure electrodes for high-performance asymmetric supercapacitors

Rational design of electrode materials can often improve the energy density/power density and service life of supercapacitors. In this study, we have developed and synthesized CuWO4 @NiCoWO4 porous nanorod array supported on copper foam using a solution immersion method at room temperature, in combination with thermal dehydration and hydrothermal strategies. The distinctive porous and heterogeneous structure, along with the synergistic effects among multiple components, maximize the electrochemical properties of the active components, leading to excellent electrochemical properties of the electrode material. Consequently, high capacitance (4.048 F cm -2 at 5 mA cm -2), excellent rate performance (88.3% retention at 30 mA cm -2), and long-lasting cycling stability (83.5% retention after 20,000 cycles) can be acheived by the CuWO4 @NiCoWO4 binder -free electrode loaded on copper foam. In addition, CuWO4 @NiCoWO4//AC button -type asymmetric supercapacitors were assembled and demonstrated good energy storage performance. It can achieve an energy density of 0.35 mW h cm -2 (20.19 Wh kg - 1) and maintain an impressive capacitance retention of 96.79% after 10,000 cycles. Notably, this work introduces a new approach for preparing polymetallic tungstate composites for potential use in electrochemical energy storage devices.