A novel battery thermal management system utilizing ultrathin thermal ground planes for prismatic Lithium-ion batteries

Temperature significantly affects the energy efficiency, safety, life and performance of a lithium-ion battery pack in electric vehicles (EVs). High overall temperature and large temperature difference of the battery in fast charging (FC) can cause degradation in performance and even catastrophic failure like a thermal runaway. Besides, the increasing energy density of battery packs limits the space for the thermal management system. Therefore, we developed an ultrathin thermal ground plane-based battery thermal management system (UTTGP-BTMS), which utilizes 0.4 mm thick novel UTTGP with air cooling to dissipate the heat from the gap between batteries. Double-layer high pores per inch (PPI) mesh and wettability modification was adopted to enhance the thermal performance of the UTTGP. Before the evaluation test of the BTMS, the heat generation rates of the batteries in 2.2C to 4C fasting charging conditions are estimated by Bernardi's model. Then, the thermal performance of the novel battery thermal management system (BTMS) is experimentally investigated under 2.2C to 4C FC regimes at ambient temperatures from 10 °C to 50 °C. The BTMS is able to maintain a battery surface temperature of 55Ah Lithium iron phosphate (LiFeO₄, LFP) batteries below 42.7 °C under a 4C charge rate, 57.3 °C at 50^°C ambient temperature, respectively, and still achieve good surface temperature uniformity in all cases studied. Compared to a BTMS with copper heat spreaders, the temperature rise temperature non-uniformity, and thermal resistance are reduced by up to 23.3%, 28.4%, and 62.6%, respectively. Besides this, the effects of the pores density of the mesh in the UTTGP-BTMS are also studied by changing the sieve number of mesh, showing that a higher pore density gives better performance under large C-rates. The proposed UTTGP-BTMS showed significant performance with only submillimeter thickness in the thermoregulation of a battery pack, with the potential of being a viable solution for high-power battery thermal management in EVs.