Executive Summary : | Li-ion batteries are widely used in Electric Vehicles (EVs) due to their high energy density, low self-discharge rate, and long cycle life. However, their performance depends on the operating conditions, with the suitable range being between 15-35°C. The battery thermal management system is crucial for EVs, as it involves cooling batteries to manage heat dissipation during operation and pre-heating in cold weather conditions. Current cooling strategies include air cooling, liquid cooling, and phase change material-based cooling, which consume a significant portion of battery power during high ambient conditions. For cold ambient conditions, the performance of lithium-ion battery packs degrades significantly, necessitating pre-heating before starting. Current pre-heating systems depend on electrical heat sources, consuming significant battery charge and typically performed at a charging station. A proposed work proposes a thermochemical storage-based "thermal battery" with salt hydrate pairs as an on-board system for EVs, capable of providing heating and cooling for the Li-ion battery pack. The system includes a reversible endothermic process, where an external heat is used to dehydrate the salt and release water vapor, and an exothermic process, where heat is released while water vapor is brought back to the reactor. The proposed strategy of a double salt pair-based thermochemical energy storage system for cooling and pre-heating operations can be integrated with existing fluid loop architecture, allowing cooling/preheating through thermochemical reactions rather than battery power. The high enthalpy of reaction and release/consumption of heat at a constant temperature, absence of environmentally unfriendly refrigerants, and elimination of dependency on battery power make the thermochemical energy storage system an excellent option for battery thermal management. |