Effect of Dual-functional Electrolyte Additive on High Temperature and High Voltage Performance of Li-ion Battery

Development and application of power lithium-ion batteries are strictly restricted by their high temperature and high voltage performance, such as capacity degradation and gas swelling, which are related to not only the modified electrode material and battery design but also the electrolyte. Herein, tetravinylsilane (TVS) was applied as electrolyte additive to improve storage and cycling performances of LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite pouch cell at high cutoff voltage (4.4 V) and high temperature (45-60 degrees C). The capacity retention rate of the cell after 400 cycles (2.8-4.4 V) at 1C (1C=1.1 Ah) with mass fraction 0.5% TVS in the electrolyte is as high as 92%, compared with 82% for its counterpart without TVS. On the one hand, TVS is preferentially oxidized under high voltage, contributing to the formation of a high-temperature resistant CEI (cathode electrolyte interphase) film on the surface of NCM622 particles, which effectively inhibits generation of internal cracks in NCM622 particles and dissolution of transition metal ions. On the other hand, TVS can also be preferentially reduced and polymerized, thus forming a stable SEI film on the surface of graphite anode, which inhibits the side reaction between the electrolyte and the negative electrode.