Next-generation battery heat shield based on lithium nitrate molten-salt phase-change material for thermal-runaway prevention

Thermal runaway (TR) and TR propagation (TRP) in lithium-ion batteries (LIBs) pose critical safety risks. Here, we report a dual-function heat shield based on a molten-salt phase-change material (PCM) that concurrently manages TR and prevents TRP. The optimized LiNO 3 -KCl blend (LK90) begins melting at 142°C and absorbs 308 J g −1 of latent heat within the critical 130°C–190°C safety window. Encapsulated in a stainless-steel pouch, the PCM heat shield outperforms a commercial aerogel sheet of equal thickness, delaying the rise of critical temperatures by more than 500 s in rapid heating tests. During a 90-min thermal soak at 130°C, it successfully prevents a fully charged cell from entering TR. This work provides a passive single layer that can be retrofitted into existing electric vehicle modules, enhancing safety without added volume or active control.