Lithium solvation and anion-dominated domain structure in water-in-salt electrolytes.

Water-in-Salt (WiS) electrolytes are an emerging class of high concentration aqueous electrolytes with large electrochemical stability windows, making them attractive as green alternatives in next-generation electrochemical energy storage devices. Recent work has highlighted the existence of water-rich and anion-rich domains in WiS electrolytes, but the extent, morphology and importance of these domains are still disputed. Here, we present neutron total scattering measurements of the archetypal WiS, lithium bis(trifluoromethanesulfonyl)imide, and use empirical potential structure refinement to match the structure of a simulated system to the experimental data for two technologically relevant concentrations, revealing ion solvation, geometric isomerism and long-range structures in unprecedented detail.

Specific ion effects enhance local structure in zwitterionic osmolyte solutions.

Zwitterionic osmolytes are widely known to have a protein-protective effect against high salt concentration, but a mechanistic picture of osmolyte function remains elusive. Here total scattering is used to determine the room temperature liquid structure of two model cytosol solutions containing trimethylglycine (TMG) with either sodium or potassium chloride. H/D isotopic substitution is used to obtain differential neutron scattering cross sections at multiple contrasts in addition to an X-ray structure factor, and an Empirical Potential Structure Refinement (EPSR) simulation is fitted to the experimental data.