Balancing pH Mismatch in Electrolytic Zn-MnO₂ Batteries via a Synergetic Anion-Proton Interactive Electrolyte

Electrolytic Zn-MnO₂ batteries (EZMBs) are considered a promising technology for grid-scale energy storage due to their low cost, high specific capacity, high operating voltage and safety. However, the tradeoff between the mildly acidic environment for high-efficiency zinc deposition on anode and the high concentration of protons required to trigger the MnO₂/Mn²⁺ conversion reaction on cathode leads to the pH mismatch issue, finally causing the instability and short lifespan of current EZMBs. In this study, a synergetic anion-proton interactive (SAPI) electrolyte regulation strategy is reported to balance the pH mismatch, which can not only regulate the electrode-electrolyte interfacial microenvironment to promote the deposition of highly (002)-oriented Zn plane with high resistance to the hydrogen evolution reaction and corrosion on anode, but also accelerate the redox reaction of MnO₂/Mn²⁺ conversion on cathode, simultaneously. As a result, the SAPI electrolyte enables a 40-fold lifespan enhancement of over 5000 cycles at a current density of 10 mA cm^-2 in Zn-Zn symmetric cells as compared to the pristine electrolyte. Furthermore, the EZMBs in SAPI electrolyte achieve an elevated average discharge voltage of 0.4 V and about 10-fold stable cycling lifespan than the pristine one. This strategy provides novel insights into designing long-life EZMBs and orientational deposition of zinc anode.