This technology involves adding fluorophenylmethylsulfone (FPMS) to lithium secondary battery electrolytes to form a stable Cathode-Electrolyte Interphase (CEI) layer containing sulfone (-SO2-) groups on the cathode surface during high-voltage, high-temperature charging. This suppresses electrolyte decomposition and improves interfacial stability between the cathode and the electrolyte.
Ni-rich NCM cathode materials with a nickel content of 83% or higher have historically faced issues with active side reactions between the cathode and electrolyte during high-temperature cycling. This leads to electrolyte decomposition, metal leaching, and accelerated fluorination, resulting in increased resistance and rapid capacity fade.
This technology incorporates 0.5–1.0 wt% of FPMS into the electrolyte, which electrochemically oxidizes to form a sulfone-based CEI layer on the cathode surface. This layer inhibits the generation of fluorine (F-) species and facilitates lithium-ion transport, improving high-temperature cycle life and interfacial resistance. Applicable to high-nickel NCM83 cells for EVs and energy storage systems operating in high-temperature environments, it slows the degradation of high-capacity cathodes with minimal additives and no major changes to existing electrolyte processes.
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