Effect of Dimethallyl Carbonate Addition on Thermal Stability of Lithium Ion Batteries

The role of dimethallyl carbonate (DMAC), which has a multiple functional group, as an additive in electrolyte have been studied for improving thermal stability of lithium ion batteries (LIB). During the initial charging of the negative electrode with an electrolyte that contains the DMAC additive, film formation occurs near 1 V vs. Li/Li+. Furthermore, increases in the amount of DMAC additive are accompanied by increases in the height of the dq/dV peaks and film formation progresses. The time-of-flight secondary ion mass spectrometry (TOF-SIMS) results show that increasing the amount of DMAC additive promotes the formation of aliphatic hydrocarbons of C5 or more in the Solid-Electrolyte-Interfase (SEI) and polymerization proceeds. The temperature programmed desorption mass spectrometry (TPD-MS) results show that the DMAC additive raises the peak temperature for CO2 generation to 100°C or higher. The DMAC additive suppresses self discharge of LIB and suppresses the increase in direct current resistance (DCR) after storage at 50°C.