Glycerol‐Modified Biphasic Silicone Gel for Synergistic Thermal Transport and Dielectric Reliability

Encapsulation materials for high‐voltage power electronics are required to simultaneously ensure efficient heat dissipation and reliable dielectric insulation, yet these two functionalities are intrinsically difficult to reconcile in silicone gels due to their intrinsically low thermal conductivity and space charge accumulation at DC voltages. Here, we report a surfactant‐free biphasic silicone gel constructed by directly incorporating glycerol into an RTV‐2 polysiloxane matrix. Despite the inherent immiscibility between polar glycerol and silicone, glycerol is stabilized as dispersed microdomains within the cured network, forming a counterintuitive stable biphasic architecture. The resulting abundant interfaces act as functional regions that concurrently regulate phonon transport and charge carrier dynamics. Through interfacial polarization and trap induction, charge migration is effectively suppressed while heat transport is moderately enhanced. The optimized composite exhibits a 33.3% increase in thermal conductivity, a 48.3% enhancement in thermal diffusivity, and a 57.6% improvement in DC breakdown strength, accompanied by significantly reduced space charge accumulation. This work challenges the conventional solid‐filler paradigm by demonstrating that liquid/liquid interfaces can serve as effective functional regions for electrothermal regulation, providing a simple and scalable pathway toward encapsulation materials for power electronic systems.