Ultrathin nickel manganese nanosheets with rich oxygen-vacancy as a durability electrode for aqueous Ni//Zn batteries

Advanced aqueous batteries with abundant global reserves, large discharge capacity and long life span are crucial research objectives. Herein, a kind of aqueous Zn-ion battery was fabricated with ultra-thin Ni-Mn nanosheet electrode and zinc foil. A simple H2-annealing process was employed to handle the NiMnxOy nanosheets to form oxygen vacancy. Based on the formation of fast ion diffusion channels and the increase of active sites, the fabricated H-NiMnxOy nanosheet electrode displays an areal capacity of 0.68 mA h cm−2 at a current density of 2 mA cm−2 and an excellent cycling performance (almost no reduction after 6000 cycles). The fabricated H-NiMnxOy//Zn battery obtains a high areal capacity, up to 0.66 mA h cm−2 at a current density of 4 mA cm−2, and shows a long cycling stability (88.5% capacity retention after 5500 cycles). In particular, it has a high energy density, up to 1.13 mW cm−2 at a power density of 3.34 mW cm−2, more than many other similar devices. Thus, this research provides a new idea for the wide application of aqueous Zn-ion battery in intelligent equipment and electric vehicles.