Advanced Low‐Flammable Electrolytes for Stable Operation of High‐Voltage Lithium‐Ion Batteries

Abstract

Despite being an effective flame retardant, trimethyl phosphate (TMP_a ) is generally considered as an unqualified solvent for fabricating electrolytes used in graphite (Gr)-based lithium-ion batteries as it readily leads to Gr exfoliation and cell failure. In this work, by adopting the unique solvation structure of localized high-concentration electrolyte (LHCE) to TMP_a and tuning the composition of the solvation sheaths via electrolyte additives, excellent electrochemical performance can be achieved with TMP_a -based electrolytes in Gr∥LiNi_0.8 Mn_0.1 Co_0.1 O₂ cells. After 500 charge/discharge cycles within the voltage range of 2.5-4.4 V, the batteries containing the TMP_a -based LHCE with a proper additive can achieve a capacity retention of 85.4 %, being significantly higher than cells using a LiPF₆ -organocarbonates baseline electrolyte (75.2 %). Meanwhile, due to the flame retarding effect of TMP_a , TMP_a -based LHCEs exhibit significantly reduced flammability compared with the conventional LiPF₆ -organocarbonates electrolyte.