Butyl acrylate (BA) and ethylene carbonate (EC) electrolyte additives for low-temperature performance of lithium ion batteries

A novel modified reagent of butyl acrylate (BA) is introduced to improve the low-temperature performance of lithium-ion batteries (LIBs). Although the BA reagent has a slightly higher viscosity, it has a very low melting point and a very high dielectric constant, which makes the electrolyte have a high ionic conductivity, and finally the low temperature performance of lithium ion battery is obviously improved. The discharge capacities of BA0% were 116.67, 107.79, 95.65 and 74.31 mAh g−1 at −10 °C, −20 °C, −30 °C and −40 °C, respectively. After adding 16% BA to the electrolyte, the discharge capacities of BA16% were 127.89, 125.13, 113.28 and 91.50 mAh g−1 at −10 °C, −20 °C, −30 °C and −40 °C, with the increase of 9.6%, 16.1%, 18.4% and 23.1%, respectively. Moreover, ethylene carbonate (EC) is added as another modification reagent which can further improve the conductivity, increase the low-temperature capacity and achieve a better cyclic stability. As a result, the largest capacity could reach 169.12, 149.05, 138.15 and 108.94 mAh g−1 for the EC16% + EC10% battery, with the room-temperature capacity (identified as 180 mAh g−1) retention rates of 94.0%, 82.8%, 76.8% and 60.5% at −10, −20, −30 and −40 °C respectively, which are much higher than those of BA0%, BA 8%, BA12% and 16% batteries. The mixed additives of BA + EC can not only improve the low temperature discharge capacity, but also enhance the discharge voltage platform, which provides a new insight to improve the low-temperature performance of LIBs.