Fast-Charging Aqueous Zinc Batteries Enabled by Enhanced O–H Bond Cleavage via d-p Spin Exchange Interactions

Fast-charging aqueous zinc-ion batteries (ZIBs) are promising for sustainable energy storage; yet, precisely modulating proton (H+) intercalation and storage mechanisms remains challenging. Here, we present a cathode material composed of 4-fluorosalicylic acid (F–H2SA)-modified MnO2 (FSAMO), which exploits d-p spin exchange interactions to enhance H+ storage through facilitated O–H bond cleavage. We reveal that F–H2SA chemically bonds with MnO2, forming a Mn–O–O interface. The −COOH groups of F–H2SA induce spin polarization via d-p spin exchange interactions at this newly formed interface. Consequently, the induced spin polarization significantly accelerates electron exchange processes and promotes O–H bond breaking, thereby substantially improving H+ storage capacity in ZIBs. The FSAMO cathode achieves a remarkable capacity and practical application of 365 mAh g–1 at 0.3 A g–1. This study bridges fundamental spin chemistry and applied battery technology, offering a new approach to engineer cathode materials for ZIBs.