Impact of electrolyte incorporation on stability and combustion behavior of silicone oil-based immersion coolants

• Electrolyte introduction increases acid value, viscosity and density of SIC. • Electrolyte reduces decomposition temperature and enhances heat release, raising fire risks. • Electrolyte lowers the flash point and promotes char layer formation, intensifying fire hazards. • Combustion tests reveal electrolyte-dependent in flame height, temperature and mass loss rates. The increasing adoption of immersion cooling systems in high-power lithium-ion battery applications necessitates comprehensive safety and stability studies of coolant-electrolyte systems to mitigate thermal runaway risks. The study systematically investigates the impact of electrolyte incorporation on the physicochemical properties and combustion behavior of silicone oil-based immersed coolant (SIC) composites. Comprehensive analyses, including viscosity, acid value, thermal stability, and combustion experiments, were conducted to evaluate the compatibility, thermal degradation kinetics, and flammability of SIC composites. Electrolyte addition significantly alters the physicochemical properties of SIC with a notable increase in acid value. Thermal stability assessments demonstrate that the electrolyte reduces the onset temperature of decomposition and enhances heat release, particularly under oxidative conditions, increasing the thermal runaway risks. Combustion tests highlight a novel dual effect: while electrolyte incorporation lowers the flash point and ignition temperature, intensifying fire hazards, it also promotes the formation of a protective carbonaceous char layer, reducing smoke production. Flame height, temperature, and mass loss rates were quantitatively analyzed, showing electrolyte-dependent trends. The study provides new insights for optimizing the safety and performance of electrolyte-based immersion cooling systems.