Promoting Reversible Dissolution/Deposition of MnO₂ for High-Energy-Density Zinc Batteries via Enhancing Cut-Off Voltage

Zn//MnO₂ batteries based on the MnO₂ /Mn²⁺ conversion reaction mechanism featuring high energy density, safety, and affordable cost are promising in large-scale energy storage application. Nonetheless, the continuous H⁺ intercalation at low potential reduces the average output voltage and the energy efficiency, impeding the development of the high-performance zinc battery. In this work, a strategy was proposed of enhancing the cut-off voltage from the perspective of electrochemical parameters, toward high energy efficiency and stable output voltage of the Zn//MnO₂ battery. This strategy was beneficial to promoting MnO₂ dissolution/deposition through the increase of acidity caused by the constant accumulation of MnO₂ and inhibiting H⁺ (de)intercalation during cycling process, thereby improving the energy efficiency (83.5 %) along with the stable average output voltage (1.88 V) under the cut-off voltage of 1.8 V. This work provides a new pathway to promote aqueous zinc batteries with high energy density and stable output voltage.