Temperature significantly affects the energy efficiency, safety, life, and performance of a lithium-ion battery pack in electric vehicles (EVs). Therefore, controlling the temperature of the battery pack within a certain range has become a challenge in the development of EVs, especially in fast charging (FC) with high charge rates (C-rates). In this thesis, an ultrathin thermal ground plane-based battery thermal management system (UTTGP-BTMS) is presented, which utilized 0.4 mm thick ultrathin thermal ground planes (UTTGP) and forced air cooling provided by cooling fans. The thermal performance of the novel battery thermal management system (BTMS) was experimentally investigated at 2.2 C to 4 C FC regimes under environmental temperatures from 10 ℃ to 50 ℃. The BTMS is able to maintain a...[ Read more ]

Temperature significantly affects the energy efficiency, safety, life, and performance of a lithium-ion battery pack in electric vehicles (EVs). Therefore, controlling the temperature of the battery pack within a certain range has become a challenge in the development of EVs, especially in fast charging (FC) with high charge rates (C-rates). In this thesis, an ultrathin thermal ground plane-based battery thermal management system (UTTGP-BTMS) is presented, which utilized 0.4 mm thick ultrathin thermal ground planes (UTTGP) and forced air cooling provided by cooling fans. The thermal performance of the novel battery thermal management system (BTMS) was experimentally investigated at 2.2 C to 4 C FC regimes under environmental temperatures from 10 ℃ to 50 ℃. The BTMS is able to maintain a mean surface temperature of 55Ah lithium iron phosphate (LiFeO₄, LFP) batteries below 42.7 ℃ even at a 4 C charge rate and achieve good surface temperature uniformity in all cases. At an ambient temperature as high as 50 ℃, the proposed UTTGP-BTMS can still maintain the mean battery surface temperature under 57.3 ℃. The temperature rise, temperature uniformity, and thermal resistance gained improvements of up to 23.3%, 28.4%, and 62.6%, respectively, compared to a BTMS with the same dimensions as copper heat spreaders. The effects of different pores densities of the mesh in the ultrathin thermal ground plane were also studied. The proposed UTTGP-BTMS showed brilliant performance in controlling the temperature of the battery pack, which is capable of being a viable solution for high-power battery thermal management in EVs.