The world's automobile industries are currently moving in a speedy trend to accelerate the diffusion of electric mobility in the global market. Electric mobility has the potential to compete with internal combustion vehicles due to its significant role in i) improving public health in cities by reducing CO₂ emissions and ii) enhancing energy security to be less dependent on fossil fuels. However, electric mobility still faces a few challenges to prove themselves in the market, such as charging anxiety, fill-up-time, and range anxiety. Moreover, the most critical challenge is the thermal management system of the batteries. It is highly recommended to keep the working temperature of the battery in a range of (15-45) ̊C. The battery's efficiency decays when the battery is not in the optimum thermal range, especially in the charging/discharging processes. Also, using the batteries at high temperatures may shorten the battery life. Accordingly, a proper cooling system is essential to maintaining optimum performance and avoiding overheating, which can reduce the battery's efficiency, capacity, and longevity.

In this study, an innovative hybrid cooling system was designed to help thermal runaway by quickly detecting and controlling temperature spikes and avoiding failures. The hybrid cooling system was established for a Li-ion EV battery type Lifepo4 of Grade A 30 Ah to work in two modes. MODE-I is a natural cooling mode, while MODE-II is a passive cooling mode using the Phase Change Material (RT35HC) to absorb the generated heat in the battery and extend its operating period. The experiments were conducted during the discharge phase of the battery with a discharge rate C-rate of 1C. It was found that the passive cooling mode using PCM below 80g was unable to reduce battery surface temperature compared with the natural cooling mode. In comparison, 100g of the PCM could provide better thermal performance with a reduced battery surface temperature of 7.4^oC. During phase transitions, PCMs can absorb and release thermal energy. Such a reduction in surface temperature will increase the life cycle of the battery and allow it to be used in hot climate conditions.