Fig. 4

In-situ formation of anionic aggregates at cathode interface. a Structures of plausible coupling products of BOB²⁻ and diglyme. Calculated reaction-free energies (in eV) for the formation of anionic (green) and neutral (red color) dimers. b Optimized geometries for the dimer and higher order coupling products of BOB and diglyme. The respective charges are shown in the parenthesis. c Table showing calculated redox potentials for diglyme and its oligomers with BOB molecules. Oxidation/reduction potentials are calculated with respect to that of Li/Li⁺ couple. A positive or negative sign is used to represent reduction and oxidation potentials, respectively. d Infrared (IR) spectra comparing the intensity profiles obtained from experiment and DFT calculations. The experimental profile was obtained from an NCM cathode harvested from a Li||NCM cell after two charge–discharge cycles at a low rate of C/10. The cell contained a diglyme–LiNO₃–HFiP electrolyte with 0.4 M LiBOB as a salt additive