Joint Influence of Nitrogen Doping and Oxygen Vacancy on Manganese Dioxide as a High-Capacity Cathode for Zinc-Ion Batteries

Increasing active sites and defect control are both effective ways to enhance electrochemical performance. We introduce N doping and oxygen vacancy into electrolytic MnO2 simultaneously by a simple wet ball milling for the first time. The nanocomposites (named NEG) exhibit a high capacity of 360 mA h g–1 under 0.1 A g–1 current density which is much higher than the capacity in the theory of MnO2 (308 mA h g–1). By comparing the density functional theory calculations with the experimental data, we verify the adsorption between H+/Zn2+ and oxygen vacancies and identify that the oxygen vacancy-containing N-doped MnO2 has a much stronger adsorption effect on H+, which makes a major impact on the capacity storage. The study on the introduction of N dopants and oxygen vacancies might provide a novel idea in the development of manganese-based oxide electrode materials.