LiTFSI Solvation and Transport Properties in Mixed Electrolytes: Impact of Boron-Based Additives From Computer...

Extensive molecular dynamics simulations were performed to investigate the structure, solvation, and transport behavior of LiTFSI in solvents; 1,3-dioxolane (DIO) and dimethyl-sulfoxide (DMS) in pure form and their binary mixtures with ethylene carbonate (EC) in the presence/absence of boron-based additives, B[C₂HBNS(NO₂)₂]₃ (CBSt) and boronic acid (BOH). In DIO-based electrolytes, although significant ion pairing is observed between Li⁺ and TFSI^-, introduction of EC weakens these interactions, and further addition of CBSt disrupts Li⁺-TFSI^- coordination, indicating enhanced ion dissociation. Li⁺ shows well-defined solvation shells dominated by DIO, with EC playing a secondary role. In contrast, DMS-based electrolytes inherently exhibit weaker Li⁺-TFSI^- interactions, characterized by broader g(r) peaks, which promotes ion mobility. CBSt again mitigates the ion pairing effect. Interaction energy analysis confirms that Li⁺-TFSI^- pairing is strongest in pure DIO and weakest in DMS, with the inclusion of CBSt decreasing the interaction energy effectively. A similar trend in the solvation of Li⁺ was observed for DMS-based electrolytes. Interestingly, while DIO-based electrolytes were less effective in reducing ion-pair formation, the cation transport numbers were significantly good. In contrast, DMS-based electrolytes, in the presence of boron-based additives, improve cation transport and effectively decrease ion pairing, especially in the presence of EC and/or CBSt in the solution.