Deep eutectic solvent electrolytes based on trifluoroacetamide and LiPF6 for Li-metal batteries

New generation lithium batteries require better performances, improved safety, and sustainability. Better performances can be obtained with lithium anodes and high-voltage cathodes, which in turn pose more pressure on the electrolyte stability, which is mandatory for safety. Deep Eutectic Solvents (DESs) are promising components for safer and more environmentally sustainable electrolytes. We investigate the physico-chemical properties of DESs made with 2,2,2-trifluoroacetamide (TFA) and LiPF6. The best composition is tested against Li metal and two cathode active materials: LiFePO4 (LFP) and high voltage LiNi1-x-yMnxCoyO2 (NMC). We obtain good electrochemical performance in a Li-metal cell with LFP. Accelerated rate calorimetry shows improved thermal stability of the Li|DES|NMC cell with respect to a commercial liquid electrolyte. •A new deep eutectic solvent based of trifluoroacetamide (TFA) and LiPF6 is developed.•TFA:LiPF6 80:20 by molar ratio can be used as electrolyte in lithium-ion batteries.•The new DES is non-flammable and safer Li-ion cells can be fabricated.