Thermal Management in Lithium Battery

Cooling

Lithium-ion cells performance depends on both the temperature and the operating voltage. Lithium-Ion cells work well when cells operate within limited voltage and temperature. Otherwise, damage will occur to the cells and will be irreversible.

The battery temperature should be controlled carefully. Both excess heat and lack of heat will brings about problems.

Chemical reaction rates have a linear relation to temperature. The decrease of the operating temperature will reduce reaction rate and the capacity of carrying current during charging or discharging. In other words, the battery power capacity is decreased. Moreover, the reduction of reaction rate makes it harder to insert lithium ions into intercalation spaces. The result is the reduction of power and lithium plating causing the capacity loss.

High temperature increases the reaction rate with higher power output, however, it also increases the heat dissipation and generates even higher temperatures. Unless heat is dissipated quicker than heat is generated, the temperature will be higher and finally a thermal runaway will result.

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The battery temperature should be controlled within temperature limits to avoid the thermal issues and improve the performance. The temperature range affects the battery power and battery cycle life, see figures below. At the same time, the temperature distribution should be even to guarantee the battery performance and lifetime. That is also the reason why the battery thermal management system is necessary to the battery system.

When temperature ranges from 20°C to 40°C, battery power reaches maximum. The cycle life goes down slowly below 10°C because of anode plating and drops off quickly above 60°C due to the breakdown of electrode materials, see figure above.

Generally, the temperature must be controlled between 20°C and 40°C to ensure the performance and cycle life. Moreover, the temperature distribution is controlled under 5K to keep the safety and lifetime of battery (Pesaran, 2002). In addition, ventilation is also essential to the battery system and should be taken into account.

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