Thermoelectric Effects of Size of Microchannels on an Internally Cooled Li-Ion Battery Cell

Thermoelectric effects of size of microchannels on an internally cooled Li-ion battery cell is investigated in this paper. The liquid electrolyte was flowed as the coolant through rectangular microchannels embedded in the positive and negative electrodes. The effects of size of microchannels on the thermal and electrical performances of a Li-ion (Lithium-ion) battery cell were studied by carrying out 3D transient thermal analysis. Six different cases were designed according to the ratio of the width of the microchannels to the width of the cell from 0 to 0.5. The effects of inlet velocity of electrolyte flow, inlet temperature of electrolyte flow, and size of the microchannels were studied on the temperature uniformity inside the battery cell, maximum temperature inside the battery cell, and cell voltage. The results showed that increasing the size of the microchannels enhances the thermal performance of the battery cell; however, it causes slight decrease on the cell voltage (less than 2%). Comparison between the case with width ratio of 0.5 (Case 6) with the case without microchannel (Case 1) showed that this internal cooling method can decrease the maximum temperature of the battery up to 11.22K, 9.36K, and 7.86K for the inlet temperature of electrolyte flow of 288.15K, 298.15K, and 308.15K, respectively. Furthermore, the case with width ratio of 0.5 (Case 6) has up to 77% better temperature uniformity compare with the case with width ratio of 0.1 (Case 2). Increasing the inlet temperature of electrolyte flow enhances the temperature uniformity up to 33% and increases the cell voltage up to 3%, but it keeps the battery on higher temperatures. Furthermore, increasing the inlet velocity of electrolyte flow from 0.01m/s to 0.01m/s enhances the thermal management of the battery cell by decreasing the temperature inside the battery up to 8.09K, 6.75K, and 5.67K for the inlet temperature of electrolyte flow of 288.15K, 298.15K, and 308.15K respectively. Furthermore, it improves the temperature uniformity up to 89% and decreases the voltage less than 1%.