Electrolyte for lithium secondary batteries containing allyl phenyl sulfone and lithium secondary batteries comprising the same

Electrolyte for High-Nickel Cathodes Using Dual-Functional Allyl-Sulfone Additives to Scavenge Fluoride Ions

This technology utilizes Allyl Phenyl Sulfone (APS), which contains both allyl and sulfone groups, as an additive in lithium-ion battery electrolytes. It forms a stable Cathode-Electrolyte Interphase (CEI) layer on the cathode surface and improves electrode interface stability by scavenging F- ions from the electrolyte.

Ni-rich NCM cathode materials face issues where electrolyte decomposition during charge/discharge cycles generates F- species, leading to transition metal dissolution and surface corrosion. This results in a significant decline in cycle performance under high-temperature conditions.

This technology uses an APS additive at a concentration of 0.1 wt% to less than 0.5 wt% of the total electrolyte weight. The sulfone group acts as an ion conductor and electronic insulator on the cathode surface to suppress electrolyte decomposition, while the allyl group reacts with nucleophilic F- ions to remove them. This approach can be applied to EV cells using high-nickel NCM cathodes and energy storage systems operating at high temperatures, strengthening the CEI layer and reducing capacity loss caused by transition metal dissolution with only a small amount of additive.

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Key Features:

• Lithium secondary battery electrolyte comprising an allyl phenyl sulfone additive, a solvent, and a lithium salt
• Allyl phenyl sulfone additive contained at 0.1 wt% to less than 0.5 wt% of the total electrolyte weight
• Allyl functional group within the additive that reacts with and scavenges nucleophilic F- species
• Cathode-Electrolyte Interphase (CEI) layer formed between the cathode and electrolyte, containing sulfone and allyl functional groups

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