Construction of porous phenolphthalein-based polymer coating to enable highly stable zinc metal anodes

Aqueous zinc-ion batteries (AZIBs) are recognized for their commercial viability due to their low cost, high safety, and substantial theoretical capacity. However, the challenges posed by dendrite growth and side reactions of zinc ions hinder the widespread adoption of AZIBs. In this work, a new porous phenolphthalein-based polymer (PPH-CN) is synthesized through the polymerization of phenolphthalein and 2,6-difluorobenzonitrile and served as a protective layer of zinc anode. The PPH-CN layer not only effectively separates the zinc anode from aqueous electrolyte to suppress side reactions, but also provides abundant zincophilic sites to facilitate the deposition of zinc ions. As a result, the Zn@PPH-CN symmetric batteries achieve a notably stable cycle lifespan of 1820 h at a current density of 1 mA cm⁻², which is thirteen times longer than that of bare Zn. Under the protection of PPH-CN, the zinc anode exhibits a high average Coulombic efficiency (CE) of 99.7% after 3550 cycles in the Zn@PPH-CN//Cu asymmetric battery. The capacity retention rate of Zn@PPH-CN//NH₄V₄O₁₀ full batteries reaches 89.6% after 1000 cycles at 1 A g⁻¹. Furthermore, density functional theory (DFT) simulations identified the Zn²⁺ storage sites of PPH-CN, thereby demonstrating the viability of PPH-CN as interface coatings of zinc anode. This work offers valuable insights into the development of high-performance aqueous battery.

Graphical Abstract