Improvement on the storage performance of LiMn2O4 with the mixed additives of ethanolamine and heptamethyldisilazane

Abstract The commercial LiMn 2 O 4 are added into the LiPF 6 -based electrolyte without or with the mixed additives of ethanolamine and heptamethyldisilazane to be exposed in air at 60 °C for 2–6 h, and the effect of different electrolytes on the storage behavior of LiMn 2 O 4 materials and LiMn 2 O 4 /Li cells at elevated temperature is investigated comparatively for the first time by FTIR, SEM, TEM, XRD and charge–discharge measurements. The results show that the electrochemical performances of LiMn 2 O 4 exposed in the LiPF 6 -based electrolyte become worse gradually with the storage time increasing. However, when the mixture of ethanolamine and heptamethyldisilazane as electrolyte additives is added into the LiPF 6 -based electrolyte, it can stabilize the original morphology and spinel structure of LiMn 2 O 4 greatly and improve the storage performance of the material and LiMn 2 O 4 /Li cells effectively. As the commercial LiMn 2 O 4 is exposed in the LiPF 6 -based electrolyte with additives for 4 h at 60 °C, the initial discharge capacity of 97.7 mA h g −1 at 0.1 C and the capacity retention of 89.14% at 1 C rate after 150 cycles are much better than that LiMn 2 O 4 exposed in the LiPF 6 -based electrolyte under the same conditions. Furthermore, the LiMn 2 O 4 /Li cells using the LiPF 6 -based electrolyte with additives exhibit higher initial discharge capacity before storage and higher capacity retention after storage at 60 °C for a week compared to the cells without additives in the LiPF 6 -based electrolyte.