In Situ Growth of Core–Shell Heterostructure CePO₄@CuCo₂S₄ As Advanced Electrodes for High-Performance Supercapacitor

The design of multicomponent core–shell heterostructures is considered to be an efficacious way to develop excellent performance supercapacitor electrode materials. A new strategy CePO₄@CuCo₂S₄ core–shell heterogeneous structure is devised by preparing porous CePO₄ nanosheets as cores via hydrothermal reaction and solid-state phosphating methods and electrochemically deposited CuCo₂S₄ nanosheets as shells. Binder-free three-dimensional (3D) porous CePO₄@CuCo₂S₄ nanosheets grown on foam nickel substrate can provide an ordered porous nanoframe, promote electrode/ion transport, and generate the effective synergy of good conductivity from CePO₄ and excellent redox activity from CuCo₂S₄. As a consequence, the CePO₄@CuCo₂S₄ electrode exhibits an outstanding specific capacitance (2897.8 F g^–1 at 0.5 A g^–1), a superb capacity retention rate (70.1% at 20 A g^–1), and excellent cycle stability (after 10,000 cycles or maintain 94.4%), superior to those of bare CePO₄ and CuCo₂S₄ electrodes. In addition, an asymmetric hybrid supercapacitor is assembled by CePO₄@CuCo₂S₄ and activated carbon, when the energy density is 80.4 Wh kg^–1 and the corresponding power density is 799.5 W kg^–1.