An efficient radiative cooling composite film for Lithium-ion battery thermal management systems

With the rapid development of electric vehicles (EVs), heat accumulation in lithium-ion batteries (LIBs) during high-rate charging and discharging has become a significant safety concern. Excessive temperatures not only accelerate battery performance degradation, but also trigger thermal runaway. Therefore, the development of an efficient, low-energy-consumption battery thermal management system (BTMS) is of great importance. Here, a hollow silica/polydimethylsiloxane (SiO 2 /PDMS) composite coating with radiative cooling capability was prepared and applied to LIBs to achieve the passive thermal regulation. The material with a stable composite structure exhibited excellent roughness, hydrophobicity and thermal stability when 25 vol% hollow SiO 2 microspheres were uniformly dispersed within the PDMS matrix. Mechanistic analysis indicated that the hollow SiO 2 microspheres induced a rough surface and numerous internal interfaces. These structural features, along with the high infrared emissivity of PDMS in the 8–13 μm atmospheric window, enabled efficient light scattering and radiative cooling. Under a 1C discharge rate, the operating temperature of coated LIBs was significantly reduced, with a maximum reduction of approximately 11 °C. Moreover, the coating could effectively suppress heat accumulation and improve the uniformity of the battery's surface temperature distribution, demonstrating an excellent radiative cooling performance. Therefore, the proposed passive radiative cooling film based on a SiO 2 /PDMS composite structure would expand the application of radiative cooling materials in the field of electrochemical energy storage, and provide new material strategies for constructing efficient, low-energy-consumption thermal management systems of LIBs.