Photoinduced Proton‐Cation Cascade Boosting Ion Intercalation Dynamics in Photo‐Assisted Zinc‐Ion Batteries

Abstract While photo‐assisted ion batteries represent a promising energy storage frontier—with light irradiation significantly improving performance—their development remains hindered by a fundamental knowledge gap, as existing theories struggle to fully account for improved light‐driven ion intercalation. This work discovers the photoinduced proton‐zinc ion intercalation cascade mechanism, establishing a theoretical framework that explains the synergistic proton‐cation interplay and its role in capacity enhancement under illumination. Through light‐induced charge transfer, photogenerated electrons drive proton intercalation, which induces the deprotonation of Zn 2+ ‐coordinated water molecules due to the limited availability of free protons in the electrolyte. This deprotonation is energetically favored because of the lower deprotonation barrier of Zn 2+ ‐coordinated water compared to uncoordinated water, thereby accelerating zinc‐ion desolvation and promoting Zn 2+ intercalation. Consequently, the synergistic H + /Zn 2+ co‐intercalation enables an exceptional areal capacity of 12.86 mA h cm −2 under illumination in a photo‐assisted zinc‐ion battery with a high mass‐loading of 30 mg cm −2 . This work elucidates a proton‐cation cascade mechanism that governs light‐driven intercalation dynamics, providing the missing link between photo‐excitation and enhanced battery performance.