Water-in-Salt LiTFSI Aqueous Electrolytes: Liquid Structure

Both computational and experimental X-ray scattering show the liquid structure transform from liquid network at low salt concentration to TFSI- network at high salt concentration

Scientific Achievement

In the highly concentrated 20 m LiTFSI solution, the water network existing in low concentration aqueous electrolytes is completely broken and is replaced by a TFSI- network; in spite of local heterogeneity, the liquid structure is homogeneous in general instead of forming TFSI- rich or water rich domains.

Significance and Impact

The proposed liquid structure is fundamentally different from those suggested previously and indicates that the observed high apparent transference number of Li+ is due to mechanisms that needs further study.

Research Details (18pt Arial, Bold)

  • X-ray total scattering and FTIR experiments were perfomed for LiTFSI aqueous electrolyte as a function of LiTFSI concentration.
  • Classical molecular dynamics (CMD) simulation was also carried out for the same electrolytes and the calculated results agree with experiments quantitatively, therefore validated the accuracy of the simulations.
  • Detailed liquid structure was analyzed based on the validated CMD simulations.

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DOI: 10.1021/acs.jpcb.1c02189

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