Self-Sacrificial Sustained-Release Effects Synergistically Modulate Dual-Electrode Interfacial Chemistry in a Biphasic Electrolyte for Electrolytic Zn–MnO2 Batteries

Electrolytic zinc–manganese batteries (ZMBs) featuring high energy density and low cost hold significant potential for large-scale energy storage. However, their development is hindered by severe zinc corrosion and poor reversibility of the Mn2+/MnO2 conversion, originating from drastic pH fluctuations and an acidic environment. Herein, we propose an organic/inorganic self-stratifying electrolyte, which synergizes with the self-sacrificial sustained-release Zn(BF4)2 to regulate the zinc interface and MnO2 conversion chemistry. The design innovatively utilizes the in situ hydrolysis of BF4– to create an HF/F– buffer and free F– ions. The former stabilizes cathode pH and promotes uniform deposition and deep conversion of MnO2. Additionally, the released F– fosters a robust ZnF2-rich SEI on the zinc anode in a water-lean environment (organic phase), effectively suppressing corrosion and side reactions. Therefore, the zinc-symmetric battery with an organic phase exhibited a lifespan of over 650 h, exceeding conventional aqueous electrolytes by 38-fold. The Zn–MnO2 batteries deliver exceptional stability for 1800 cycles at 2C with an average Coulombic efficiency of 98.7%. This biphasic buffering-interface regulation strategy provides a generalizable approach to decouple interfacial challenges, which is promising for extension to other corrosion cell systems.