Surface degradation of lithium-manganese spinel in contact with electrolyte solution comprising lithium hexafluorophosphate

A set of computational and experimental methods was used to study side chemical interactions in the lithium-ion cathode half-cell based on LiMn2O4 (LMO) in the temperature range of 25–60°C. It was shown that the degradation of LMO electrode starts upon contact of LiMn2O4 particles with a standard (basic) electrolyte solution (1 m LiPF6 in a mixture of ethylene carbonate and dimethyl carbonate (1:1, wt.)). Significant increase in the resistance of the interface layer with time accompanies this process. It has been established that the cause of the degradation without current applying is the relative thermodynamic instability of LiMn2O4 and the lithium salt LiPF6. The equilibrium interaction products were determined, and the mechanism of the critical influence of temperature on the degradation of LIB with lithium-manganese spinel was refined. A model was proposed for the formation of a primary surface layer at the LiMn2O4/electrolyte interface, which explains the distinctive features of the degradation processes in this system.