Thermal hazard assessment for three C rates for a Li-polymer battery by using vent sizing package 2

Abstract

The Li-polymer battery (LPB) offers numerous advantages such as long cycle life and thinner volume. A major challenge is supplying energy to the battery with higher efficiency and superior thermal safety. In this study, LPB samples with different charging rates (1C, 3C, and 5C) were prepared under specific conditions for withstanding 100 cycles of the aging test, and their temperature variation was recorded at different times. Vent sizing package 2 and a customized stainless-steel test cell were used for determining the thermal hazard characteristics, such as apparent exothermic onset temperature (T0), self-heating rate (dT dt−1), pressure rise rate (dP dt−1), pressure–temperature profiles, maximum temperature (Tmax), and maximum pressure (Pmax), to reveal the thermal runaway mechanisms. We investigated the relationship between the charge/discharge rate and thermal stability for the LPB samples. In the discharge process, operation at a higher C rate was associated with a higher-temperature rise. The results revealed that the batteries preparation with higher C rate (i.e., 5C) had the most unstable properties. During the runaway reaction, the lowest T0, Tmax, and Pmax values were 133.0 °C, 530.0 °C, and 910.1 kPa, respectively. Compared with the batteries exterior, the 5C tests exhibited explosion and fire hazards. These results suggest that the 5C charging rate is unsuitable for batteries, whereas the 1C and 3C rates are appropriate in terms of thermal stability.