Sucralose with bifunctional groups as a functional additive enhancing the interfacial stability of zinc metal anodes via interfacial molecular chemistry regulation

Abstract

Recent years have witnessed renewed interest in aqueous zinc-ion batteries, but challenges persist due to the rapid capacity decay and irreversible cycling of zinc anodes, primarily stemming from uncontrolled dendritic growth. To overcome this issue, in this work, sucralose is utilized as a functional electrolyte additive to enhance the stability and electrochemical performance of the zinc metal anode. According to the experimental characterization and theoretical calculations, sucralose molecules tend to be adsorbed on the Zn metal surface due to the presence of hydroxyl and chlorine groups, which regulated the solvation structure of Zn²⁺ near the interface of the electrode and electrolyte to inhibit dendrite formation and facilitate uniform Zn metal plating. Utilizing sucralose as an electrolyte additive, a significantly improved cycling lifespan of 1800 cycles under 5 mA cm⁻²/1 mA h cm⁻² and a coulombic efficiency as high as 99.9% are retained in Zn–Cu asymmetric cells. Moreover, the assembled Zn-ion full cells with the sucralose additive in the electrolyte exhibit a high-capacity retention of 73.5% after 1000 cycles, which was almost increased by 300% in comparison with the cells using the pure ZnSO₄ electrolyte. Furthermore, the assembled punch full cells can maintain a capacity of 166.3 mA h g⁻¹ and stable cyclability with a capacity retention of 82.5% after 100 cycles at 5 A g⁻¹. Our innovative approach provides insights into using functional electrolyte additives to regulate the solvation structure of Zn²⁺ ions near the electrode/electrolyte interface as a promising electrolyte design strategy for enhancing the performance and sustainability of aqueous zinc-ion batteries.