Abstract: The charge and discharge performance of lithium-ion batteries deteriorates sharply at low temperatures.In this paper,a heating system for a battery pack consisting of sixteen 37 Ah lithium-ion batteries is designed,which includes electric heating film,transformer oil,silica aerogel plates,etc.Then,by using the ANSYS software,a finite element model of the heating device of lithium-ion battery pack is constructed,and the heating effect of the heating system on the battery pack is analyzed.Finally,the effectiveness and safety of the heating method are verified by experiments.The results show that ( 1) in different low-temperature environments,the time of pre-heating the battery pack to make its temperature higher than 0 ℃ shows a linear change; ( 2) the pre-heating time is 35min and 12 min respectively at the extremely low-temperature of － 30 ℃ and the common low temperature of － 10℃,which means that the heating effect is significant; ( 3) after pre-heating,the discharge voltage of the battery pack increases and thus the discharge performance of the battery pack is improved; and ( 4) the temperature uniformity of the battery pack can be kept within 3℃ by means of oil circulation or standing.

Key words: low temperature environment, lithium-ion batteries, electric heating film, heating