Thermoresponsive self-blocking electrolytes and separators for intrinsically safe lithium batteries

Thermal runaway remains the foremost safety challenge in lithium-ion batteries, spurring intensive research into its root causes and the development of intrinsic fail-safe mitigation strategies. Among the emerging strategies, thermoresponsive self-blocking electrolytes and separators represent a promising class of engineered materials whose ionic conductivity or porous microstructure undergoes rapid modulation in response to thermal excursions. By autonomously suppressing ion transport at elevated temperatures, these smart components can effectively interrupt electrochemical reactions before thermal propagation leads to catastrophic failure, thereby enabling intrinsically safe battery operation. This review critically examines the latest progress in such thermoresponsive self-blocking electrolytes and separators, emphasizing the molecular and structural design principles, underlying thermal-response mechanisms ( e.g. , phase transitions, pore collapse, and sol-gel switching), and their electrochemical performance in lithium battery configurations. Although these innovations have significantly advanced the field of battery safety, challenges persist in balancing a rapid thermal response with long-term interfacial stability and ionic conductivity. We outline key hurdles and propose future directions for developing multi-functional, intelligent architectures that concurrently enhance the safety and electrochemical performance, paving the way for the reliable deployment of high-energy-density batteries in electric vehicles, portable electronics, and grid-scale storage.