Battery electrolyte

A method of manufacturing a battery cell comprising:

• positioning a separator between a negative electrode and a positive electrode;
• dissolving 0.7M lithium hexafluorophosphate, 0.3M lithium bis(fluorosulfonyl)imide, 1 wt. % fluoroethylene carbonate, 1 wt. % vinylene carbonate, and 0.3 wt. % of a multifunctional additive in a solvent mixture of ethylene carbonate and ethyl methyl carbonate in a 25/75 volume ratio to form an electrolyte, wherein the multifunctional additive is (s)-n-(1-(2-((4-(3-(trifluoromethyl)phenyl)piperazin-1-yl)methyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)-3-methyl-2-(2-oxo-1,3-diazaspiro[4.5]decan-1-yl)butanamide;
• and
• saturating the negative electrode, the positive electrode, and the separator with the electrolyte.

An electrolyte for a battery cell comprising:

• 0.7M lithium hexafluorophosphate;
• 0.3M lithium bis(fluorosulfonyl)imide;
• 1 wt. % fluoroethylene carbonate;
• 1 wt. % vinylene carbonate;
• 0.3 wt. % of a multifunctional additive, wherein the multifunctional additive is (s)-n-(1-(2-((4-(3-(trifluoromethyl)phenyl)piperazin-1-yl)methyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)-3-methyl-2-(2-oxo-1,3-diazaspiro[4.5]decan-1-yl)butanamide;
• and
• a solvent mixture of ethylene carbonate and ethyl methyl carbonate in a 25/75 volume ratio.