Engineering active sites on hierarchical ZnNi layered double hydroxide architectures with rich Zn vacancies boosting battery-type supercapacitor performances

Designing metal-cation defects with desired architectures is a big challenge for boosting electrochemical performances. Herein, we report ultrathin ZnNi layered double hydroxide (LDH) nanosheets with rich Zn vacancies (V Zn ) uniformly anchored on CuO nanowire skeletons for high performance capacitive electrode via a zeolitic imidazolate frameworks-8 derived approach. The optimized V Zn -defect electrode displays high area capacity of 3967 mF cm −2 at a current density of 2.0 mA cm −2 . Moreover, an all solid-state hybrid supercapacitor constructed with the V Zn -defect sample and activated carbon delivers a maximum energy density of 1.03 mWh cm −3 at a power density of 9.3 mW cm −3 . Mechanism studies indicate that V Zn regulates the electronic structure of ZnNi LDH nanosheets for electron conductivity and surface Faradaic reactions. The work may disclose the role of metal-cation defects in affecting the electrochemical activity at atomic level for developing high performance supercapacitors.