Katja Vlasov

Novel Fluorinated Solvents and Additives for Lithium-Ion Batteries

Abstract The performance of rechargeable lithium-ion batteries, such as conductivity, solid electrolyte interphase (SEI) formation, thermal and electrochemical stability, low- and high-temperature features, and safety are improved by new fluorinated components, namely, electrolyte salts, novel solvents (cosolvents), and additives. The electrochemical studies showed that, hitherto unknown lithium sulfonates, besides the positive property not to generate HF in the presence of moisture, show good lithium-ion conductivity, a high electrochemical stability, and good SEI formation properties. In addition, these salts are noninflammable and applicable in a wide temperature range. We developed efficient and safe methods for the synthesis of these salts in multigram scale. A new SEI-film-forming cosolvent for propylene carbonate was explored, as well as a new fluorinated carbonate as a cosolvent and SEI additive. Both components are able to improve the safety of the electrolytes. A new cyclic sulfonamide turned out to be a very useful electrolyte additive, having a positive impact on the formation of an SEI layer on the negative electrode, increasing the thermal stability, decreasing the capacity loss, and decreasing aging. A neutral cyclic carbene–PF5 adduct can be applied as an effective shutdown overcharge protection additive.