Bis(di-tert-butyl)-4-dimethylaminophenylphosphine as electrolyte additive to improve the electrochemical performance of LiNi0.8Co0.1Mn0.1O2

•Bis-4TMPA was added into the electrolyte to improve the electrochemical performance of NCM811.•Bis-4TMPA could undergo electrochemical oxidation, promote partial electrolyte solvolysis and participate in the formation of the SEI film.•The phosphine group in Bis-4TMPA can react with the oxygen species released from the cathode surface, which protects electrolytes from oxidative decomposition.•The nitrogen-containing group in Bis-4TMPA can react with HF to reduce the corrosion on the electrode.•The reversibility of the H2 ⇋ H3 phase transition was improved when the NCM811 cycled in the electrolyte with Bis-4TMPA, which reduced the generation of microcracks.