Abstract: Lithium-ion battery is widely used in energy storage system and electric vehicle as power source due to its superior performance. It is an important means to ensure the safety of lithium-ion battery by choosing a reasonable thermal management mode according to the thermo-physical properties and operating conditions of lithium-ion battery. In this paper, the models of air-cooling single and module of cylindrical lithium-ion battery are constructed, and the influence of thermal conductivity anisotropy on the cooling performance of the battery is discussed from the aspects of maximum temperature, maximum temperature difference and temperature distribution uniformity. The results show that the internal heat transfer process of lithium-ion battery is dominated by the radial thermal resis-tance, which directly determines the internal temperature difference of single battery and the temperature distribution uniformity between different single batteries in the battery module. Moreover, it is pointed out that, during the design of battery structure, in order to improve the temperature uniformity, the size of battery in the cross-plane direction should be reduced as much as possible on the premise of ensuring the energy density.

Key words: lithium-ion battery, air cooling, thermal conductivity anisotropy, maximum temperature, maximum temperature difference