Free carbonate-based molecules in the electrolyte leading to severe safety concerns of Ni-rich Li-ion batteries

The safety of Li-ion batteries is one of the most important factors, if not the most, determining their practical applications. We have found that free carbonate-based solvent molecules in the hybrid electrolyte system can cause severe safety concerns. Mixing ionic liquids with a carbonate-based solvent as the co-solvent at a fixed salt concentration of 1 M LiPF can lead to free carbonate-based molecules causing poor charge storage performance and safety concerns.