An Organic/Inorganic Hydrogel Composite Artificial Protective Layer Assists High-Performance Zinc Metal Anodes

Although aqueous zinc-ion batteries are considered ideal candidates for grid-scale energy storage systems, their practical applications are still significantly limited by harmful side reactions associated with zinc anodes, particularly dendrite formation and hydrogen evolution. To address these issues, a composite hydrogel interfacial layer SCN(SA/g-C3N4) was developed in this study. This multifunctional hydrogel coating demonstrates exceptional ion-selective properties, effectively preventing direct contact between H2O and the zinc anode while efficiently facilitating Zn2+ transport and nucleation. Additionally, the hydrogel matrix contains a substantial amount of free Zn2+, ensuring efficient and continuous ion replenishment at the electrode–electrolyte interface. Furthermore, g-C3N4 provides numerous zincophilic sites, promoting uniform Zn2+ deposition during cycling. The synergistic effect of this organic–inorganic composite structure endows the zinc anode with remarkable stability during electrochemical cycling. The fabricated SCN@Zn||SCN@Zn symmetric cell maintained stable cycling for 2800 h under the testing condition of 2 mAh cm–2/2 mA cm–2. The SCN@Zn||MnO2 full cell exhibited an 82.3% capacity retention after 1400 cycles at a current density of 2 A g–1. The zinc anode material modified using this method shows practical feasibility for energy storage applications.