Lithium-ion battery (LIB) is an important technology for various energy storage applications, but its thermal characteristics affect its effectiveness, life, and safety, which in serious cases may cause an explosion. Many studies have been conducted to improve the performance of LIBs using petroleum-based phase change materials (PCMs) in a passive thermal regulation technique. However, these PCMs are petroleum-based, hence they are not sustainable and detrimental to the environment. Therefore, this work aims to find a new, sustainable, bio-based PCM for regulating LIB's thermal characteristics. Palm fatty acid distillate (PFAD) was chosen as the bio-based PCM in this work and its impacts on the thermal regulation and electrical performance of the LIB were evaluated experimentally. In the experiment, a battery module that consisted of nine rechargeable LIB cells type 18,650 (arranged accordingly to provide 12.6 V and 15000mAh) was assembled in a rectangular aluminum container filled with PFAD. The module was tested under three different electrical loads of 50 W, 100 W, and 150 W, representing the discharging C-rates of 0.27C, 0.56C and 0.83C, respectively. The results indicated that the application of PFAD as the bio-based PCM contributed to the reduction of the LIB cells' temperatures by 9.8 , 19.5 , and 12.4 , and also to the increase of the cell's electrical power by 17 , 20 , and 43 , for each of the loads, respectively. These results proved that the future of utilizing PFAD as the bio-PCM for the thermal regulation of LIB is very encouraging. © 2023 Elsevier Ltd