Interfacial adsorption and chelation approaches for Long-Life aqueous Zn batteries

Despite the advantages of high theoretical capacity and low cost, the commercialization of zinc-ion batteries (ZIBs) still faces the challenges of Zn dendrite growth and corrosion reactions. Here, chitosan (CS) is chosen as a dual-functional electrolyte additive with non-toxicity, low cost, and biodegradability features to simultaneously optimize the Zn2+ coordination structure and electrode interfacial environment. Density functional theory calculations and experimental results show that CS molecules can adsorb on the Zn electrode to form a water-poor electric double layer, inhibiting hydrogen evolution and side reactions. The specific adsorption induces preferential growth of the Zn(0 0 2) plane to form a flat and compact deposition layer. Furthermore, CS additives can decouple the original Zn(H2O)62+ structure through the chelation between CS and Zn2+, effectively reducing the water activity in ZIBs. Consequently, the Zn||Zn cells with CS electrolyte show excellent stability of 3000 h. Additionally, the Zn||MnO2 full cells show excellent stability with a capacity retention of 86.79 % after 500 cycles at 1 A g−1. This study presents a facile and feasible strategy to stabilize Zn anodes by regulating the electrode interface and solvation structure.