Facile electrochemically induced vacancy modulation of NiCo2O4 cathode toward high-performance aqueous Zn-based battery

• An ultrafast and controllable electrochemical activation process is developed. • The content of oxygen vacancies can be precisely modulated by the EA process. • The oxygen-deficient NiCo 2 O 4 exhibits a 5-fold enhancement of specific capacity. • The assembled Zn battery delivers a high energy density of 682.4 Wh kg −1 . Transition metal oxides are highly promising cathode materials in rechargeable Zn-based batteries owing to their low cost, high theoretical capacity and good reversibility. Nevertheless, intrinsically low conductivity and sluggish redox reaction kinetics normally result in their inferior specific capacity and poor rate capability, which critically constrains the practical performance of Zn-based batteries. Herein, an ultrafast and controllable electrochemical activation (EA) process is developed to effectively enhance the electrochemical performance of NiCo 2 O 4 cathode. Systematic studies reveal EA process triggers in situ reconstruction of NiCo 2 O 4 lattice by weakening the coordination of Co-O bonds, resulting in the formation of abundant oxygen vacancies (octahedral Co 2+ ). These oxygen vacancies increase the charge carrier density and endow the superficial metallic active sites with higher electrochemical activity, which synergistically accelerates the electrochemical reaction kinetics. The oxygen-deficient NiCo 2 O 4 exhibits a remarkable capacity of 418.9 mAh g −1 at 1 A g −1 , which is nearly 5-fold higher than that of pristine NiCo 2 O 4 . Furthermore, the oxygen-deficient NiCo 2 O 4 //Zn battery presents an extremely high energy density (682.4 Wh kg −1 ) and excellent power density (50.8 kW kg −1 ), surpassing most of the reported aqueous rechargeable batteries. This work provides a facile and effective vacancy modulation strategy for the development of advanced materials utilized in energy and catalysis fields.