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Ion–solvent interactions in nonaqueous electrolytes are of fundamental interest and practical importance, yet debates regarding ion preferential solvation and coordination numbers persist. In this work, in situ liquid SIMS was used to examine ion–solvent interactions in three representative electrolytes, i.e., lithium hexafluorophosphate (LiPF₆) at 1.0 M in ethylene carbonate (EC)–dimethyl carbonate (DMC) and lithium bis(fluorosulfonyl)imide (LiFSI) at both low (1.0 M) and high (4.0 M) concentrations in 1,2-dimethoxyethane (DME). In the positive ion mode, solid molecular evidence strongly supports the preferential solvation of Li⁺ by EC. Besides, from the negative spectra, we also found that PF₆^– forms association with EC, which has been neglected by previous studies due to the relatively weak interaction. In both LiFSI in DME electrolytes, however, no evidence shows that FSI^– is associated with DME. Furthermore …