Internally Referenced DOSY-NMR: A Novel Analytical Method in Revealing the Solution Structure of Lithium-Ion Battery Electrolytes.

A novel methodology is reported on the use of internally referenced diffusion-ordered spectroscopy (IR-DOSY) in divulging the solution structure of lithium-ion battery electrolytes. Toluene was utilized as the internal reference for 1H-DOSY analysis due to its exceptionally low donor number and reasonable solubility in various electrolytes. With the introduction of the internal reference, the solvent coordination ratio of different species in the electrolytes can be easily determined by 1H-DOSY or 7Li-DOSY. This new technique was applied to different carbonate electrolytes, and the results were consistent with a Fourier transform infrared (FTIR) analysis. Compared to conventional vibrational spectroscopy, this IR-DOSY technique avoids the complicated deconvolution of the spectrum and allows determination of the solvent coordination ratio of different species in electrolyte systems with two or more organic solvents.