A Novel Mn2+-Additive Free Zn/Mno2 Battery with 2.4 V Voltage Window and Enhanced Stability

Recently, aqueous Zn/MnO2 batteries have attracted considerable attention due to their safety, low cost, and environmental friendliness. However, capacity decay caused by Mn dissolution greatly limits their further development. Herein, LiTFSI is employed as an electrolyte additive to inhibit water decomposition, and the cathode passivation process is also implemented to further widen the voltage window. The cathode passivation process not only inhibits water decomposition at high voltage but also suppresses Mn dissolution during discharge. Meanwhile, the addition of LiTFSI can also effectively suppress hydrogen evolution, significantly improving the Coulombic efficiency (CE) and stability of Zn stripping/plating processes. As a result, a 2.4 V voltage window is achieved and the dissolved Mn is redeposited on the cathode at ≈ 2.2 V. The Mn2+-additive free Zn/ε-MnO2 battery maintains 80% capacity even after 300 cycles at 0.5 A g-1 and also exhibits long term stability of more than 2,000 cycles at 5.0 A g-1 with a specific capacity of ≈ 113.1 mAh g-1