Electronic-ionic polymer composite with proton-coupled electron transfer reaction: From low N/P ratio to high zinc utilization for aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) are potential next-generation energy-storage systems. However, their intrinsically disordered deposition behavior limits their practical performance. We introduce electronic–ionic polymer composites (EIPC) onto Zn anodes via a proton-coupled electron transfer (PCET) mechanism. Protons and electrons are synchronously transferred to accelerate interfacial redox reactions. This framework facilitates reversible Zn deposition. The EIPC layer strongly binds to the Zn surface, significantly modulating its electrochemical behavior. At the electrode-electrolyte interface, the EIPC layer promotes the preferential plane of (002)-oriented Zn during continuous deposition and stabilizes the solvation structure. Consequently, EIPC@Zn achieves depth of discharge (DOD) cycling stability (≈51%) and a high cumulative plating capacity (3040 mAh cm⁻² at 4 mA cm⁻²). In high mass loading (25.8 mg cm⁻²) MnO₂ pouch cell tests, EIPC@Zn maintains for 100 cycles with a low N/P ratio (0.74) and high DOD (≈85%) under 1 A g⁻¹. These findings present a novel and effective approach for enhancing the electronic-ionic conductivity of advanced aqueous metal anode technologies.