Use of ethyl acetate for improving low-temperature performance of lithium-ion battery

In this work, the effect of ethyl acetate as a co-solvent is investigated on the low-temperature performance of the lithium-ion battery. The cyclic voltammetry measurements show that the solid electrolyte interface formation as a result of the reduction of ethyl acetate occurs in 2.15 V on the graphite surface which is higher than that of electrolyte without ethyl acetate in 1.97 V. Addition of ethyl acetate to electrolyte decreases the charge transfer resistance and also the total resistance of lithium-ion battery. The scanning electron microscopy images show that the morphologies of layers formed by reduction of electrolytes without and with ethyl acetate at room temperature are different due to the facile reduction of ethyl acetate. At 25 °C, the capacity retentions of the 18650-type graphite/LiCo1/3Ni1/3Mn1/3O2 (NMC111) full-cells without and with ethyl acetate are 96.84% and 93.16% after 50 cycles, respectively, compared to their initial discharge capacities. At − 40 °C, the cell without ethyl acetate cannot operate due to the electrolyte freezing while the cell containing ethyl acetate shows the 59.33% capacity retention compared to its discharge capacity at room temperature.