Screening the Physical Properties of a Series of Water-in-Salt Electrolytes Using Computer Simulations

Water-in-salts form a new family of electrolytes with properties distinct from the ones of conventional aqueous systems and ionic liquids. They are currently investigated for Li-ion batteries and supercapacitors applications, but to date most of the focus was put on the system based on the LiTFSI salt. Here we study the structure and the dynamics of a series of water-in-salts with different anions. They have a similar parent structure but they vary systematically through their symmetric/asymmetric feature and the length of the fluorocarbonated chains. The simulations allow to determine their tendency to nanosegregate, as well as their transport properties (viscosity, ionic conductivity, diffusion coefficients) and the amount of free water, providing useful data for potential applications in energy storage devices.