UV-Polymerized Zincophilic Ion-Enhanced Interfacial Layer With High Ion Transference Number for Ultrastable Zn Metal Anodes

Aqueous zinc-ion batteries (AZIBs) are considered one of the most viable options for large-scale energy storage applications due to their high theoretical capacity and abundant reserves. However, issues such as dendritic growth and water-induced corrosion reaction of the zinc anode have hindered their commercialization. To address these challenges, in situ generated multifunctional poly(caffeic acid) (PCA) interface with confined Cu sites and abundant oxygen-containing groups was constructed on the surface of the zinc metal anode via ultraviolet (UV) treatment. The smooth and compact PCA effectively prevents the zinc anode from corrosion by active water in the electrolyte, while the synergies of zincophilic groups and the confined copper sites constitute 3D ion channels of PCA skeleton accelerates the migration of Zn²⁺ and enhance deposition kinetics, thus lowering Zn²⁺ desolvation energy. The symmetric cells using the PCA-modified Zn anode demonstrated stable cycling for over 2500 h and 2200 h at current densities of 1.0 and 5.0 mA cm⁻², respectively, much better than controls. Additionally, the assembled PCA@Zn//I₂ full cell enabled continuous cycling over 1000 cycles at a current density of 1.0 A g⁻¹ and presented reliable operation over 100 cycles in a pouch cell configuration.