Oxygen vacancy-rich CuBi2O4/Bi2O3 heterostructure and flower-like NiCo layered double hydroxides electrodes for high-performance asymmetric supercapacitors

The rapid development of high-performance electrode materials for asymmetric supercapacitors (ASCs) needs to solve the bottleneck problem of low energy density. Compared with the positive electrode material, the development of the negative electrode material is relatively lagging and has become one of the key "short board" to limit the energy density of the supercapacitor device. In this study, the oxygen vacancy-rich CuBi2O4 nanoparticles are triumphantly anchored on the interface of rod-like Bi2O3 after calcination to prepare the heterostructure CuBi2O4/Bi2O3 (CBO/BO) composites by the combination of simple hydrothermal process and calcination. Due to the unique anchoring mode, heterogeneous structure, and oxygen vacancy introduction, the CBO/BO as the cathode processes the capacitance of 294.7 mAh g(-1) at 1 A g(-1). In addition, bimetallic NiCo layered double hydroxides (NCL) with the 3D flower-like structure prepared by a one-pot process is used as the positive electrode and the specific capacitance of 186.7 mAh g(-1) at 1 A g(-1). The assembled water-based NCL// CBO/BO ASC triumphantly amplifies the potential window to 1.7 V, achieves the ultrahigh energy density between 91.8 and 52.9 Wh kg(-1) at 850-8500 W kg(- 1), and maintains the remarkable cycle consistency. Density functional theory calculation fully proves that oxygen vacancy and copper doping can significantly improve the electrochemical performance of electrode materials. Therefore, the research results in this paper afforded a feasible way to further develop asymmetric supercapacitors with ultrahigh energy density.