Reshaping static aqueous Zn─Br battery chemistry without liquid Br₂ for intrinsic safety and cycle durability

Emerging static aqueous Zn─Br batteries offer substantial cost and energy density advantages but suffer from toxic Br₂ formation and polybromide shuttling. Here, we report a universal electrode engineering for advanced Zn─Br battery via incorporating layered materials into the cathode, reshaping the working mechanism from conversion to intercalation-conversion. Findings confirm that Br^- intercalate-converts to Br^-0.14 within unsaturated N-rich g-C₃N₄, effectively avoiding liquid Br₂ formation and suppressing its toxicity and diffusion. Consequently, the self-discharge of cell remarkably decreases from 96.5 to 9.5% following 12 hours resting. Through controlling 48.7% Zn depth-of-discharge and industrial-level mass loading 40 mg_(KBr) cm^-2, the multilevel pouch cell with ampere hour-level capacity exhibits 750 cycles, outperforming aqueous counterparts at high mass loadings. This electrode engineering is applicable to other layered materials, underscoring its practical universality. These findings not only unlock the full potential of aqueous Zn─Br batteries but also enrich the chemistry landscape of aqueous battery family.