Electrostatic self-assembled polymer film empowers the interfacial structure and chemistry of Zn anode for enhanced stability

The instability of Zn anode caused by interfacial issues arising from parasitic reactions and dendrite growth remains a bottleneck for developing rechargeable aqueous zinc metal battery (RAZMB). Herein, an electrostatic self-assembled DS polymer film using poly(diallyldimethylammonium) (PDD⁺) and poly(sodium 4-styrenesulfonate) (PSS⁻) as units is designed to stabilize Zn anode by modulating the interfacial structure and chemistry. PDD⁺ polycations chemically bond directly to Zn anode and then electrostatically interact with PSS⁻ polyanions rich in sulfonate groups. The DS polymer film not only blocks direct contact between Zn and H₂O but also flattens the anode surface potential, which effectively inhibits parasitic reactions and improves the diffusion behavior and deposition kinetics of Zn²⁺ ions to achieve uniform Zn deposition. Moreover, the as-formed “externally elastic and internally rigid” interface endows DS-Zn anode with excellent cycling stability and reversibility. Consequently, the symmetric cell assembled with DS-Zn delivers an ultralong cycling stability of 3000 h. DS-Zn||Cu cell achieves a high CE of 99.7 % over 1600 cycles, outperforming most reported work. Meanwhile, the electrochemical performance of DS-Zn||VO₂ battery is markedly improved. The approach of designing and fabricating DS polymer film to modulate interfacial structure and chemistry for stabilizing Zn anode may boost the practical implementation of RAZMBs.