The distributed temperature abatement by the phase changing materials for battery in electric tools and its influence on aging

Abstract

Battery thermal management system is of great importance, and there are numerous methods at present. Due to spatial efficiency, phase-change materials are particularly welcomed in applying electric tools where extremely high current (10–15 C) and temperature (40 °C) are typical. However, the C-rate and environmental temperature in many studies are not large enough to meet this need. In this study, Samsung 18,650 20R NCM batteries with wrapping storage materials are taken as the research object. This study explores the temperature distribution from the battery core to the surface at high environmental temperature (40 °C) and large discharging current (15 C). The proposed model and its predicted temperature results are validated with experimental data. The results indicate that the full-discharged battery's surface temperature decreases by 18.60 °C compared with the naked battery (103.78 °C) when 2 mm PCMs are applied (85.17 °C). In contrast, the core temperature reduction is much lower, only from 139.70 °C to 133.29 °C, causing the radical temperature difference to rise from 35.92 °C to 48.12 °C. The significant temperature difference and high internal temperature are that the heat generation rate exceeds the rate of heat conductivity at high temperatures and large currents. The study further evaluates the effects of internal high temperature on the battery lifetime at electric tools' working conditions. The single discharge capacity of batteries with 2 mm PCMs is approximately 80–100 % more than that of the naked batteries, while the capacity of the former fades 90–250 % faster than the latter.