Dyness Knowledge | Overview of Thermal Management of Energy Storage Batteries

When lithium batteries are charged and discharged normally, chemical reactions occur between the positive and negative electrode materials and the electrolyte inside the battery, generating a large amount of heat energy, causing the battery temperature to rise. Generally speaking, the power consumption of the battery in the standby state is very small, and the corresponding current flowing through the battery is also very small, and there is generally no obvious heating phenomenon. However, when the battery is rapidly discharged, the equivalent load resistance of the battery is small, and the battery discharges with a large current during operation. After the battery discharges part of its power, the internal resistance increases. If the battery continues to be discharged at a high intensity, a considerable part of the energy will be consumed in the internal resistance of the battery, causing the battery to heat up. On the contrary, when the battery is charging, due to the excessive charging current, the battery power increases, and the internal resistance will also increase accordingly, which will also cause the battery to heat up.

Long-term excessive heating of the battery will not only accelerate the aging process of the product itself, but also shorten its life. At the same time, long-term excessive heating of the battery will cause the air inside the sealed battery pack to expand violently, causing the battery to bulge. In severe cases, the battery may even explode, endangering the user's personal and property safety.

Therefore, technicians developed a thermal management system for energy storage batteries. For single energy storage batteries, currently commonly used solutions to solve battery heating problems are generally divided into two categories.

• The first type is to reduce battery heating in advance through the battery’s intelligent management control system (BMS) combined with temperature sensors. This solution will set the program in advance on the BMS to monitor and control the current, voltage, temperature and other data of the battery pack in real time during the charging and discharging process. Set the alarm threshold to identify in advance whether the heat produced by the battery during operation will affect the safe use of the product. Once this value is exceeded, an alarm will be automatically transmitted to the system and the user. If the heat continues, the circuit can be automatically cut off.
• The second category is to use physical methods to cool the battery. The external thermal management system starts the external cooling device to cool down the battery by receiving the signal sent by the battery BMS combined with the temperature sensor. Among them, the simplest operation and lowest cost is fan cooling, but the heat dissipation efficiency is average. When the surrounding environment is high, it is easy to cause insufficient heat dissipation or local uneven heat dissipation. Another option is a liquid cooling system. The coolant flows through the battery surface through the external fluid circulation system to absorb the heat of the battery product. This method has higher heat dissipation efficiency and stability, and the corresponding installation cost is also increased, and it also requires professional coolant pipeline design.

In short, thermal management of energy storage systems is of great significance for improving energy efficiency and extending battery life.

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