Unraveling the Proton Co‐Insertion Chemistry through Electrolyte Hydrogen‐Bond Intervention for Zinc‐Manganese Dioxide Batteries

ABSTRACT Aqueous Zn‐MnO 2 batteries are promising for large‐format energy deployment due to their inherent safety and environmental compatibility. Nevertheless, their commercial implementation is critically bottlenecked by the elusive proton co‐insertion mechanism at the cathode, in contrast to the relatively well‐understood anode stability. Herein, we unveil the underlying H + ‐storage phenomenon within MnO 2 via a tailored hydrogen‐bond intervention strategy. Our findings reveal that the catastrophic capacity degradation originates squarely from the second discharge plateau, which is intrinsically governed by the hydrogen‐bond network. By reinforcing the hydrogen‐bond environment, we effectively modulate proton intercalation kinetics and suppress the excessive H + flux that otherwise triggers structural collapse. While traditional aqueous electrolytes lead to severe manganese dissolution and irreversible vacancy formation, our strategy preserves the structural integrity of the MnO 2 ’s 2 × 2 tunnel framework. Theoretical calculations confirm that the incorporation of H + into α‐H x MnO 2 weakens the Mn─O bonds with notable vacancy formation. Leveraging these mechanistic insights, we demonstrate Zn‐MnO 2 pouch cells under stringent practical conditions—high areal capacity (2.62 mAh cm −2 ), restricted N/P ratio (2.2), and lean electrolyte (30 µL mAh −1 )—yielding a specific energy of 167 Wh kg −1 . Meanwhile, this electrolyte demonstrates an excellent one‐year cycling lifespan at −10°C. This work provides insight for high‐performance aqueous batteries.