From Charge Storage Rulebook Rewriting to Commercial Viability of Zinc-Manganese Batteries

Aqueous zinc-manganese oxide (Zn-MNO) batteries represent a compelling solution for grid-scale energy storage due to their inherent safety, cost-effectiveness and ecological compatibility. However, the commercialization of this technology faces critical challenges including insufficient electrode durability, limited areal capacity output, and fundamentally ambiguous charge storage principles, which collectively hinder practical implementation. Through systematic mechanistic investigation, a previously overlooked phase evolution paradigm is revealed. It involves that Mn₃O₄ cathode undergoes a partially in situ phase transition to MnO₂ during the initial charging process, forming a hybrid Mn₃O₄/MnO₂ cathode. This self-optimized heterostructure synergistically combines structural reinforcement frameworks with enhanced ion-transport networks, enabling exceptional cycling stability over 4,500 cycles while maintaining record-high areal capacity (10 mAh cm^-2). The clarified dual-ion (H⁺/Zn²⁺) coordination mechanism and stabilized Mn²⁺/MnO₂ redox chemistry establish new design principles for manganese-based cathodes. More importantly, unprecedented scalability is demonstrated through constructing pouch cells (200 mAh) with 1000-cycle durability, achieving a practical energy density of 54 Wh kg^-1. The integrated solar-powered battery system exhibits remarkable operational safety under extreme conditions (piercing, cutting), representing one of the most practically viable Zn-MNO batteries reported to date. This work bridges fundamental mechanistic understanding with industrial-grade device engineering, charting a concrete pathway toward terawatt-hour scale renewable energy storage.