PFAS Free Organic Carbonate‐Based Electrolyte Formulation for LNMO||SiGr Cell Chemistry

Abstract A per‐ and polyfluoroalkyl substances (PFAS) free electrolyte formulation for the high voltage lithium nickel manganese oxide (LNMO)||silicon‐graphite (SiGr) per‐ and polyfluoroalkyl substances (20 wt.% silicon) cell chemistry is developed. The high upper cut‐off voltage of 4.9 V, together with the substantial volume expansion of the silicon‐graphite negative electrode, imposes stringent demands on the electrochemical stability of the electrolyte. A newly developed PFAS free electrolyte formulation incorporating lithium difluoro(oxalato)borate (LiDFOB) alongside cost‐effective organic carbonate solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) enables stable operation of LNMO‖SiGr cell chemistry. Improved galvanostatic cycle life from 145 cycles to 245 cycles (69 %) can be achieved in the presence of 4 wt.% LiDFOB. LiDFOB effectively suppresses the transesterification often observed in organic carbonate‐based electrolytes by scavenging lithium alkoxides and leads to a reduction of transition metal (TM) dissolution. These properties contribute to the formation of an effective solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI), resulting in improved galvanostatic cycling stability and overall electrochemical performance. The developed PFAS free electrolyte formulation constitutes a promising pathway for high‐voltage lithium ion cells, combining environmental safety with high electrochemical performance.