A weak acid-responsive porous polyelectrolyte membrane enables the high efficiency of a zinc anode interface

Abstract

Polymer coatings are promising candidates as artificial interfacial materials due to their significant barrier properties and zincophilicity, whereas modified zinc anodes for high depth of discharge (DOD) remain a major challenge. Herein, we present a novel approach that combines electrostatic complexation with phase separation in a weak-acid solution, which induces the formation of acid-responsive porous polyelectrolyte membranes, leading to an extended lifespan of the zinc anode of up to 900 h at a high current density of 40 mA cm⁻². Additionally, the Zn@PEI-PSSNa anode demonstrates excellent zinc utilization, operating for up to 200 h at an ultra-high DOD of 97.3%. The Zn@PEI-PSSNa‖Cu cell further exhibits long-term cycling stability with a super-high coulombic efficiency (CE) of 99.8% for nearly 4000 h. Experimental analysis and simulations indicate that the sulfonate and amino functional groups, along with the porous structure, could improve zincophilicity and facilitate the transport of Zn²⁺, thereby promoting uniform zinc deposition, accelerating the desolvation process and mitigating side reactions.