Theoretical screening and mechanistic insights into alcohol and sugar additives for aqueous zinc-ion batteries

Abstract

Through theoretical screening of various alcohol and sugar molecules, this study has discovered that the performance of aqueous zinc-ion batteries (AZIBs) can be enhanced by adding xylitol and sucrose as electrolyte additives. Specifically, this work employs an integrated theoretical screening framework (frontier orbitals, electrostatic potential, Fukui functions, and adsorption energy mapping), which represents a novel methodological approach. It was found that xylitol and sucrose molecules can undergo adsorption behavior on the zinc anode surface, forming a molecular adsorption layer that reduces the occurrence of side reactions and dendrite growth. By performing in-depth theoretical calculations, different modification mechanisms exhibited by xylitol and sucrose were determined. For the first time, this study mechanistically distinguishes xylitol (modulating short-range structure) and sucrose (modulating long-range structure), revealing two distinct yet effective molecular pathways. Xylitol primarily influences the short-range coordination structure of Zn²⁺. At certain concentrations, xylitol molecules enter the first solvation shell of Zn²⁺, forming [Zn (H₂O)₅(C₅H₁₂O₅)]²⁺ complexes. In contrast, sucrose molecules mainly affect the long-range coordination structure of Zn²⁺. This study provides theoretical guidance for the design and development of electrolyte additives for AZIBs.