“Water Respiration” Polymer Interface Helps Aqueous Zinc-Ion Batteries Achieve Long Life at High Capacity

Abstract Aqueous zinc-ion batteries (AZIBs) are promising energy storage systems due to their intrinsic safety, high volumetric energy density, low reduction potential, and the abundance of zinc. However, challenges such as dendrite formation and parasitic side reactions hinder their large-scale commercialization. In this study, we synthesized a polydiacetone acrylamide @ acrylamide (PAD) coating in situ on zinc foil to solve these problems. The coating inhibits side reactions by preventing water from contacting the zinc surface. The functional groups on the coating facilitate uniform deposition of Zn between the coating and the zinc foil, which is beneficial to improve battery life. PAD has “water respiration”, which can effectively reduce the mechanical performance degradation caused by polymer coating swelling. As a result, the symmetric cell demonstrated a remarkable cycling stability of 1200 h at 10 mA cm–2 and 10 mAh cm–2. The asymmetric cell achieved over 600 cycles (∼1.7 months) with an average Coulombic efficiency of 99.5% at 1 mA cm–2 and 1 mAh cm–2. Furthermore, the full cell exhibited 5600 cycles with 93.4% capacity retention at 5 A g–1 and 8 mg cm–2 mass loading. This work provides a simple and effective strategy: in situ “water respiration” coating significantly improves the cycling performance of zinc-ion batteries and demonstrates an improved idea for aqueous zinc storage devices.