Recent Advances in Epoxy‐Based Dielectric Materials With Improved Electrical Insulating Properties

Epoxy resins (EPs) have long served as a key dielectric material for electrical insulation in high‐voltage systems. However, the increasing demand for higher reliability, superior insulating performance, and long‐term stability under complex operating conditions has driven intensive efforts toward material innovation. Among various strategies, the incorporation of functional fillers to form polymer composites has proven especially promising. This review synthesizes recent progress in the design, characterization, and understanding of EP‐based composites for high‐voltage insulation. We first summarize the diverse classes of fillers, ranging from microscale to nanoscale, and analyze how their morphology, dispersion, and interfacial engineering contribute to enhanced dielectric strength and charge transport control. The underlying mechanisms governing trap formation, breakdown behavior, and electrical conduction are discussed in detail through both experimental observations and theoretical models. In addition to experimental advances, we highlight the growing role of computational methods in revealing interfacial phenomena and guiding material optimization. The review concludes by outlining practical applications, identifying current challenges that limit large‐scale implementation, and proposing key research directions for next‐generation high‐performance EP‐based insulating materials.