Passive Cooling Technology for Safer, Longer-Lasting EV Batteries

Electric-vehicle batteries generate a great deal of heat, especially during fast charging, hard acceleration, and hot weather. If this heat is not removed quickly and evenly, battery cells wear out faster, lose driving range, and can even become unsafe. Today’s battery cooling systems rely on pumps, fans, and complex liquid loops that consume power, add weight, and increase cost.

This project is developing a new type of battery cooling system that works without pumps, fans, or external power. Instead, it uses natural boiling and condensation (similar physics behind a refrigerator) to move heat away from the batteries automatically.

The system surrounds battery cells with a special heat-absorbing material that melts when the battery gets warm, soaking up excess heat. Tiny metal particles are mixed into this material so heat spread quickly and evenly. When the material warms up, a safe refrigerant inside small tubes begins to boil. The rising vapor naturally flows to a cooler section of the system, where it turns back into liquid and releases the heat to the surrounding air. The liquid then flows back to the battery area by gravity, repeating the cycle, all without a pump.

By combining heat-absorbing materials with a self-circulating cooling loop, this technology keeps battery temperatures lower and more uniform during demanding driving and charging conditions. That means: (1) longer battery life, (2) better driving range, (3) improved safety, (4) lower energy use for cooling.

The project will build and test a working prototype and develop design guidelines that can be used by electric-vehicle manufacturers, battery developers, and transportation agencies. The same technology could also be used for electric buses, trains, ships, and stationary energy storage systems, helping California meet its clean-transportation and climate goals.