This research investigates the use of n-octadecane as a phase change material (PCM) for the thermal management of lithium-ion batteries. During simulation runs in ANSYS CFD the research team evaluates heat distribution together with the n-octadecane phase change processes during its entire solidification and melting period. N-octadecane serves as a heat conduction agent during battery charging and behaves similarly as a heating source during discharging to achieve proper battery temperature control. The temperature interval from 28 °C to 30 °C serves as the total melting point range for n-octadecane and possesses a latent heat of fusion value equal to 200 kJ/kg. The localization of battery-PCM interface after melting happens primarily due to the thermal conductivities of solid-phase n-octadecane at 0.222 W/mK and liquid-phase n-octadecane at 0.198 W/mK. Multiple research investigations confirm the temperature regulating characteristics of n-octadecane to safeguard batteries from thermal failure together with preserved operational functioning. Research findings indicate that PCM phase change efficiency improves when cylindrical holes in the PCM casing receive optimized placement for better heat distribution. To achieve long-term battery safety and stability of battery performance active cooling systems need to integrate with PCM technology. Data shows that n-octadecane thermal systems possess potential as electric vehicle battery storage management solutions because they ensure stable performance and safety levels.