Lithium-ion battery functionality over broad operating conditions via local high concentration fluorinated ester electrolytes

Facilitating widespread adoption of electric vehicles will require next-generation battery systems that can operate reliably over a large temperature range, at high operating voltage, and under fast charging rates. Herein, a novel class of nonflammable fluorinated ester-based local high concentration electrolytes (LHCEs) are described. When cycled in commercially relevant graphite/LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) pouch cells, these electrolytes demonstrate improved capacity retention compared to carbonate-based electrolytes under multiple usage conditions including high voltage (4.5 V), fast charge (4C, 15 minutes), and low temperature (−20 °C) without sacrificing capacity retention at elevated temperature (40 °C). Low carbon, high fluoride cathode electrolyte interphases formed by the LHCE system yield a significant reduction in charge transfer impedance during cycling and contribute to capacity retention. These results demonstrate that using fluorinated esters in a LHCE modality enables creation of a new class of nonflammable electrolytes that can successfully operate over broad operating conditions.