Design and Performance Investigation of a Self-Healing Anti-Flashover Coating Based on β-Cyclodextrin–Adamantane Host–Guest Interactions

Surface flashover is a common insulation failure in high-voltage equipment. Conventional anti-flashover coatings can raise flashover voltage, but scratches and microcracks often reduce their long-term reliability because most coatings cannot repair damaged interfaces. Here, a self-healing anti-flashover coating was prepared by introducing β-cyclodextrin–adamantane host–guest units into a fluorocarbon resin (FEVE) matrix. Quantum chemical calculations, molecular dynamics simulations, and electrical tests were used to examine host–guest stability, trap regulation, charge dissipation, scratch healing, and DC flashover behavior. The β-CD–Ad inclusion structure was thermodynamically favorable and remained stable during simulation. HG incorporation changed the surface trap distribution of FEVE and promoted charge transport by introducing high-density shallow traps. The 10 wt% HG/FEVE coating showed the best overall performance, with a DC flashover voltage 15.12% higher than that of pure FEVE. After damage and water-assisted repair, it retained 96.57% of its flashover performance. The improved performance is attributed to two coupled effects: reversible host–guest interactions help close damaged interfaces, while shallow-trap-dominated charge transport reduces surface charge accumulation and local electric-field distortion. This work offers a route for designing repairable anti-flashover coatings for high-voltage insulation.