Dynamically cross-linked polyethylene vitrimers: An alternative approach to high-performance high-voltage cable insulation

High voltage direct current (HVDC) cables enable reliable and efficient underground and undersea power transmission, especially large-scale offshore renewable energy transmission. HVDC cable insulation, however, has been a challenging obstacle. The prevailing thermosetting cross-linked polyethylene (XLPE) suffers from space charge issues from byproducts formed during peroxide cross-linking, while thermoplastic insulation lacks sufficient thermomechanical strength. Herein, we introduce dynamically cross-linked polyethylene (DTPE) as an alternative approach to high-performance HVDC insulation. It serves as thermoplastic during manufacturing and recycling but thermoset in operation. The dynamically cross-linked networks endow DTPE with high resistance against creep comparable to XLPE. Meanwhile, insulating performances of DTPE surpass substantially state-of-the-art XLPE insulation, showing an improvement by 36.8 % in volume resistivity and a reduction of 94.9 % in space charge accumulation. Its high reprocessability (efficiency over 94 %) also ensures a prolonged lifespan in various applications. In addition, DTPE retains high breakdown strength even at elevated temperatures (e.g., 90 °C), demonstrating excellent thermal stability under operational stresses. Excellent insulating, thermo-mechanical, and recyclable properties are co-achieved in DTPE, making it a promising candidate for next-generation HVDC cable insulation.