Inorganic-Dominated Interphase Enabled by Tuning Solvation Configuration for 4.8 V Lithium-Ion Batteries.

Abstract

Constructing a dense inorganic component-dominated cathode electrolyte interphase (CEI) to meet the long-term cycling requirements of ultrahigh voltage cathodes has been a crucial challenge. Nevertheless, this goal is difficult to achieve in traditional electrolyte compositions due to the inevitable decomposition of organic solvents. Herein, by utilizing the localized mismatch between the strongly coordinating hexafluorophosphate anion (PF6-) and the weakly coordinating solvent 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide (TFDMSA), abundant aggregates (AGGs) emerged under a regular Li salt concentration of 1 m lithium bis(fluorosulfonyl)imide (LiFSI) + 0.1 m LiPF6 in TFDMSA. This anion-rich Li+ solvation structure results in an inorganic-dominated LiF-rich CEI to suppress phase transitions of lithium-rich manganese-based cathode materials (LLMO). Consequently, the prepared LLMO||Li half-cells demonstrate a capacity retention of 80.7% after 350 cycles at 4.8 V. This work advances the practical application of new electrolyte systems by proposing a new approach to construct anion-dominated Li+ solvation structures in local environments.