Battery Thermal Management in Electrical Vehicle

The heat-related issues of the battery are the key factors that determine its performance, safety, life and cost. 

First of all, the temperature level of lithium-ion batteries directly affects their energy and power performance in use. When the temperature is low, the available capacity of the battery will rapidly decay. Charging the battery at a too low temperature (such as below 0°C) may cause an instantaneous voltage overcharge phenomenon, which will cause internal lithium deposition and cause a short circuit. . 

Secondly, the heat-related issues of lithium-ion batteries directly affect the safety of the batteries. Defects in the manufacturing process or improper operation during use may cause partial overheating of the battery, which will cause a chain exothermic reaction, and eventually cause serious thermal runaway events such as smoke, fire or even explosion, which threatens the lives of vehicle drivers and passengers Safety. 

In addition, the operating or storage temperature of lithium-ion batteries affects their service life. The suitable temperature of the battery is about 10~30°C, too high or too low temperature will cause the battery life to decay quickly. 

The large-scale power battery makes the ratio of its surface area to volume relatively reduced, the internal heat of the battery is not easy to dissipate, and it is more likely to have problems such as uneven internal temperature and excessive local temperature rise, which further accelerates battery degradation, shortens battery life, and increases users’total cost.

The battery thermal management system is one of the key technologies to deal with battery heat-related issues and ensure the performance, safety and life of power batteries. The main functions of the thermal management system include: 

1) Effective heat dissipation when the battery temperature is high, to prevent thermal runaway accidents; 

2) Warm-up when the battery temperature is low, increase the battery temperature, and ensure the charging and discharging performance at low temperatures And safety; 

3) Reduce the temperature difference in the battery pack, inhibit the formation of local hot zones, prevent the battery from decaying too quickly at high temperature locations, and reduce the overall life of the battery pack. 

Heat dissipation principle: The battery pack adopts passive heat dissipation. A thermal pad is pasted between the battery pack and the aluminum heat sink. The thermal  interface materials transfers the temperature to the aluminum plate, and the aluminum plate exchanges heat with the air.

Heat dissipation principle: The battery pack adopts passive heat dissipation. A thermal conductive sheet is pasted between the battery pack and the aluminum radiator. The thermal silicone sheet transfers the temperature to the aluminum radiator, and the aluminum radiator exchanges heat with the air.