Front‐Loading Zn 2+ via Lattice‐Breathing‐Enabled Early‐Stage Co‐Intercalation for Ultrastable Zn‐Ion Batteries

ABSTRACT Manganese oxide cathodes for aqueous zinc‐ion batteries present a fundamental performance dichotomy, where the rapid kinetics of H + insertion are offset by structural degradation through acidification and manganese dissolution, whereas the more structurally compatible Zn 2+ insertion is hindered by sluggish diffusion and severe lattice strain. This conventional trade‐off, stemming from the sequential or competitive nature of these ion‐storage pathways, has long constrained the achievable capacity and cycling stability. Here, we report that In 3+ incorporation into δ‐MnO 2 creates a dynamically adaptive lattice through controlled local strain fields, activating effective transport pathways for ultrafast charge propagation. Crucially, multimodal characterization reveals an unconventional ion‐storage mechanism in which the In 3+ ‐modified host enables concerted Zn 2+ /H + co‐insertion initiating at the onset of discharge. This front‐loaded co‐intercalation mechanism, facilitated by the breathing framework, ensures efficient charge compensation while minimizing deleterious H + ‐dominant processes, thereby preserving crystallographic integrity. Consequently, the In‐δ‐MnO 2 cathode exhibits exceptional kinetics with significantly reduced ion‐migration barriers, delivering a high specific capacity of 310.6 mAh g −1 at 0.5 A g −1 and sustaining 25 000 cycles with minimal decay at 5 A g −1 . This work establishes dynamic lattice breathing as a generalizable design principle to reconcile fast ion transport with structural reversibility.