Improving the capacity of zinc-ion batteries through composite defect engineering.

Aqueous zinc-ion batteries (ZIB) are favored because of their low cost and high safety. However, as the most widely used cathodes, the rate performance and long-term cycle performance of manganese-based oxides are very worrying, which greatly affects their commercialization. Here, MnO2 with composite defects of cation doping and oxygen vacancies was synthesized for the first time. Cation doping promoted the diffusion and transport of H+ and oxygen vacancies weakened the zinc-oxygen bond, allowing more electrons to be added to the charge and discharge process. The combination of these makes α-MnO2 obtain a specific capacity of up to 346 mA h g-1. This inspired us to use different combinations of defect engineering strategies on the materials which can be implemented as a potential method to improve performance for the modification of ZIB cathode materials, such as cation vacancies and anion doping.