Experimental investigation of the effects of thermal insulation materials produced for passive thermal control of lithium-ion batteries at low temperatures on battery discharge performance

In this study, studies were carried out to reduce the negative effects of cold weather conditions on batteries and the loss of performance in batteries. Using locally sourced raw materials, new materials with non-flammability, lightweight, and high mechanical and thermal insulation properties were produced and tested. Three samples with optimal properties were selected and coated on the inner surface of the designed battery enclosure. In the second phase of the study, a test setup was created to conduct battery temperature and performance tests under low-temperature conditions. To perform tests on a battery pack with a nominal voltage of 24V and a nominal capacity of 20Ah, three different driving profiles were developed. These tests were conducted at 0°C, -5°C, and -10°C, with and without insulation, and compared with the results obtained at the battery's optimal operating temperature. The results showed that the insulation samples significantly impacted the battery's heating process. The insulation materials, characterized by low thermal conductivity and low heat dissipation, effectively retained the heat generated during the battery's operation and gradually released it into the battery enclosure. Thermal control improved battery performance efficiency by 5% at 0°C, 10% at -5°C, and 10% at -10°C compared to the uninsulated condition. Practical electrochemical energy usage efficiency was found to be over 90% for most discharge durations. Additionally, the discharge performance of the insulation samples was found to be related to the insulation thickness. Coating with EPWSO insulation material in thicknesses of 1.5 cm, 2.5 cm, and 4 cm was examined, and battery efficiency increased for each insulation thickness compared to the uninsulated condition. The results indicated that the insulated battery enclosures provided more thermal energy to heat the batteries, thus restoring their electrochemical performance.