Non-aqueous electrolyte containing fluoride salt and electrochemical device comprising the same

Imide-based electrolyte with trace sodium fluoride additive to prevent aluminum current collector corrosion

This technology suppresses the oxidative corrosion of metal components, such as current collectors and casing materials, in high-voltage and high-temperature environments by adding a small amount of fluoride salt (MFx), such as NaF, to a lithium imide-based electrolyte to generate fluoride anions (F-).

Unlike LiPF6, conventional lithium imide salts (such as LiN(SO2F)2) do not generate fluoride ions, which leads to the corrosion of aluminum cathode current collectors under harsh conditions like high voltage, high temperature, and overcharging. This results in performance degradation, including self-discharge, capacity loss, and increased internal resistance.

This technology involves dissolving lithium imide salt in a non-aqueous organic solvent, such as EC and DMC, and adding 0.007 to 0.1 wt% of a fluoride salt like NaF to enhance the oxidation resistance of the aluminum current collector. It can be applied to electrolyte design for EV cells using high-voltage cathodes and ESS modules exposed to high-temperature environments, allowing for broader use of imide-based electrolytes without concerns regarding current collector corrosion.

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Key Features:

• Imide salt included as a lithium source for the electrolyte, represented by LiN(CxF2x+1SO2)(CxF2x+1SO2), where x is an integer of 0 or greater
• Non-aqueous organic solvent containing ethylene carbonate and dimethyl carbonate in a 3:7 volume ratio to dissolve the lithium imide salt
• NaF additive contained in the non-aqueous imide electrolyte in a range of 0.007 to 0.1 wt% based on the total weight of the electrolyte
• Electrochemical device comprising a secondary battery that includes the non-aqueous imide electrolyte between a cathode and an anode

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