Mixed Ion-Electron Conductors for Dendrite-Free Aqueous Zinc Batteries

The practical implementation of aqueous rechargeable zinc batteries (ARZBs) is often limited by unstable Zn metal anodes, where nonuniform Zn²⁺ deposition and parasitic interfacial reactions induce dendrite formation, corrosion, and hydrogen evolution. To address these challenges, we developed a conductive polymer-ionic liquid composite coating composed of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/3-methlimidazolium:tetracyanoborate (PEDOT:PSS/p-MIM:TCB) as an artificial protective layer on Zn electrodes. The incorporation of the ionic liquid induces controlled phase separation within the PEDOT matrix, generating efficient Zn²⁺ transport channels and maintaining stability in aqueous environments. In addition, the work-function difference between PEDOT:PSS/p-MIM:TCB and Zn forms an electron-modulation interphase that regulates interfacial electron transfer, homogenizes Zn²⁺ flux, and suppresses dendrite growth. As a result, Zn symmetric cells exhibit stable cycling for 144 h at a current density of 10 mA cm^-2 with an areal capacity of 0.5 mAh cm^-2. Furthermore, full cells paired with α-MnO₂ cathodes demonstrate enhanced rate capability, delivering approximately 100 mAh g^-1 higher capacity at 1000 mA g^-1 compared to cells using bare Zn anodes. This work presents an interfacial engineering strategy that combines ion-channel engineering and interfacial electronic-structure modulation to stabilize Zn metal anodes in aqueous batteries.