Bond order control in sulfur-based electrolyte additive for low temperatures lithium metal batteries

Additives provide a cost-effective and practical strategy to advance battery technology development. In light of the incompatibility between commercial carbonate electrolytes and lithium metal anodes, coupled with the capacity degradation of lithium metal batteries (LMBs) under low-temperature conditions, this study examines the effect of oxygen content in the molecular structure of sulfur-based additives. Through systematic oxygen content modulation, the bond order was effectively tuned, promoting the dissociation of sulfur-containing moieties and enabling precise control of the electrolyte/electrode interface. The rationally designed sulfur-containing additive, dimethyl sulfate (DMS), demonstrates significant enhancement in battery electrochemical performance across both ambient and low-temperature conditions. DMS facilitates the formation of a robust solid electrolyte interphase (SEI) layer on the anode surface, effectively suppressing parasitic reactions and improving cycling stability. At subzero temperatures, it significantly enhances ionic transport kinetics, leading to improved capacity retention and rate capability. This study provides fundamental insights into electrolyte additive engineering, presenting a promising strategy for advancing the performance and stability of lithium metal batteries.