Regulating Interfacial Chemistry with Amphiphilic Copolymer for Durable Zinc Metal Anodes

Although rechargeable aqueous zinc-metal batteries offer conspicuous advantages for grid-scale energy storage, their application is impeded by the insufficient reversibility of the Zn anode. Irreversible processes, such as dendrite growth and parasitic water-induced side reactions, contribute to the instability of the anode/electrolyte interface. In this study, we demonstrate amphiphilic Pluronic triblock copolymers comprising hydrophobic poly(propylene oxide) (PPO) and hydrophilic poly(ethylene oxide) (PEO) segments as a new class of electrolyte additives for stabilizing Zn metal anodes. Theoretical calculations reveal preferential affinity of PPO segments to the Zn metal surface and stronger interactions of PEO segments with Zn2+ ions than with PPO segments. This unique amphiphilic property of Pluronic copolymers establishes a hydrodynamic molecular interphase between the Zn metal and aqueous media, modulating Zn electrode interface chemistry. PPO segments adsorbed onto the Zn surface create a localized water-shielding environment, mitigating water-induced side reactions, while PEO segments ensure uniform Zn2+ ion flux within the interfacial region. The synergistic interfacial regulation by the Pluronic additive is related to its molecular structure, PEO/PPO composition, and block length. With its harmonized hydrophilic-hydrophobic attributes, Pluronic F127 demonstrates notably effective interface modulation. Impressively, the incorporation of F127 into the electrolyte results in a significantly enhanced lifespan of over 9300 h at 1 mA cm–2 and 3100 h at 5 mA cm–2 in Zn symmetric cells. Zn||VO2 full cells exhibit exceptional capacity retention after long-term cycling across a wide range of current densities. This study offers pivotal insights into realizing highly reversible Zn metal anodes through interfacial chemistry regulation.