Hydrothermal synthesis of β-MnO2 nanorods for highly efficient zinc-ion storage

Rechargeable aqueous Zn/MnO 2 battery with mild electrolyte is exceedingly suitable for massive electrochemical applications due to its eco-friendliness and high safety. However, cycle stability is a crucial question in the practical application. Besides, the mechanism involved in energy storage is still controversial. Here, we show a Zn/MnO 2 battery with excellent cycle stability and provide the reasonable explanation of the operating mechanism. In this battery, the mild aqueous ZnSO 4 solution containing MnSO 4 and Na 2 SO 4 additives serves as the electrolyte and the β-MnO 2 nanorods serve as the cathode. As presented in the electrochemical tests, the specific capacity of β-MnO 2 nanorods is as high as 323.5 mA h g −1 , and its capacity retention is 94% after 1000 cycles at 3 A g −1 . The proposed energy storage mechanism is related to the reversible conversion reaction between β-MnO 2 and MnOOH. Therefore, the application of β-MnO 2 nanorods in aqueous Zn-ion battery has broad development prospects. Graphical abstract