Optimal Molecular Configuration of Electrolyte Additives Enabling Stabilization of Zinc Anodes

For the development of electrolyte additives as an effective strategy to improve the performance of zinc-ion batteries (ZIBs), most researchers focus on the functional groups but overlook the crucial molecular configuration. Herein, six stereoisomers of 2,3,4,5-tetrahydroxyvaleraldehyde with identical groups but various spatial arrangements are studied as the electrolyte additive in ZIBs. Based on the experimental analysis and theoretical calculations, the adsorption with Zn (002) plane is found to be an important dominant for the stereoisomer to enhance the Zn anode performance. Among these stereoisomers, D-Arabinose with preferential and strongest chemisorption effect modifies the anode/electrolyte interface most effectively, leading to the highest stability and reversibility of the Zn anode. The adsorbed D-Arabinose shows multifunctional effects at the interface, which not only regulates the Zn2+ solvation structure and reconfigures the hydrogen bond framework, but also facilitates uniform Zn2+ deposition by promoting 3D Zn2+ diffusion and homogenizing the electric field. Therefore, with the D-Arabinose additive in ZnSO4 electrolyte, the undesired Zn dendrite growth and side reactions including hydrogen evolution reaction, corrosion, and passivation are significantly limited during the Zn plating/stripping processes. This work proposes a new insight toward the optimal molecular configuration of additive designing for electrolyte engineering in stable ZIBs. The optimal spatial arrangement of electrolyte additive molecules for preferential and strong adsorption effect with Zn (002) plane, besides functional groups, is found to be the most important dominant for the interfacial performance of zinc-ion batteries, based on the comparison of six stereoisomers of 2,3,4,5-tetrahydroxyvaleraldehyde as electrolyte additives, indicating a new insight for additive molecule designing in electrolyte engineering of zinc-ion batteries. image