Mg ion pre-intercalated MnO2 nanospheres as high-performance cathode materials for aqueous Zn-ion batteries

Mesoporous MnO 2 nanospheres were prepared by in situ Mg ion pre-intercalation via a simple chemical method. The prepared MnO 2 shows a high reversible capacity (247 mA h g −1 at 0.3 A g −1 ).