Effects of Boron-based Additives on LiTFSI based Mixed Electrolytes

Abstract

Rechargeable Li-ion batteries are essential for modern society by enabling portable electronics, electric vehicles, and renewable energy storage. As a main component, electrolytes play a pivotal role in the operation and performance of Li-ion batteries by enabling the transport of Li-ions between the anode and cathode during charge and discharge cycles. An ideal electrolyte must exhibit high ionic conductivity, wide electrochemical stability, and compatibility with electrode materials. By combining solvents with complementary characteristics, the performance of the electrolyte can be enhanced. Further, electrolyte additives are effective in such aspects. This study explores the ion-transport and related transference properties of Li-ions in pure DIO (1,3-Dioxolane) and DMS (Dimethyl sulfoxide) electrolyte solvents and their binary mixtures with EC (ethylene carbonate), i.e., DIO-EC and DMS-EC, containing LiTFSI salt for Li-ion batteries. In addition, we have added two different boron-based electrolyte additives, a well-known B(OH)3 and another additive B[C₂HBNS(NO₂)₂]₃, which, henceforth termed as CBSt, to understand the effects of it on the mixed electrolyte. Our group previously modelled CBSt as a promising electrolyte additive. This study demonstrates that DIO and DMS, both in their pure forms and as binary mixtures with EC, significantly influence the Li⁺–TFSI⁻ interactions and solvation structures when combined with boron-based additives. These solvent systems play a crucial role in modulating ion pairing, interaction energies, and the overall ion transport behavior, directly impacting the electrolyte's physicochemical and electrochemical performance.