Temperature uniformity of a heated lithium-ion battery cell in cold climate

•Temperature uniformity of a heated Li-ion battery has been analyzed.•Factors influence on temperature uniformity of a Li-ion battery have been analyzed.•Two heat methods have been compared. At low temperatures, charge–discharge performances of lithium-ion batteries decline rapidly. Preheat is essential for an effective battery thermal management system. Temperature uniformities of lithium-ion battery cells heated by the self-heating lithium-ion battery structure (SHLB) method and the wide-line metal film (WLMF) method are studied by the transient three-dimensional heating finite element models. Under the same condition, the temperature of a lithium-ion battery cell heated by SHLB heating method is three times more uniform than that heated by the WLMF heating method. However, temperature uniformity of a lithium-ion battery cell heated by SHLB method still is poor. Effects of environment temperature, heating time, heating power, thickness of a lithium-ion battery cell and stand time after heating on temperature distribution of a lithium-ion battery cell heated have been analyzed. For the two heating methods, heating power, thickness of a lithium-ion battery cell and stand time after heating have remarkably influences on temperature distribution of a heated lithium-ion battery cell. For SHLB heating method, temperature uniformity of a heated lithium-ion battery cell is acceptable by decreasing heating power and thickness of a lithium-ion battery cell if there is no safety issue on the structure. Meanwhile, for WLMF heating method, temperature uniformity of a heated lithium-ion battery cell is also acceptable by decreasing heating power, thickness of a lithium-ion battery cell or increasing stand time after heating.