Dynamic Cross-Linked Polyethylene Networks with High Energy Storage and Electrical Damage Self-Healability

Dielectric polymers that exhibit high energy density U_e, low dielectric loss, and thermal resistance are ideal materials for next-generation electrical equipment. The most widely utilized approach to improving U_e involves augmenting the polarization through increasing the dielectric constant ε_r or the breakdown strength E_b. However, as a conflicting parameter, the dielectric loss also increases inevitably at the same time. In addition, due to the long-term work under a strong electric field or high potential, dielectric materials often produce electrical damage (electrical tree), which is one of the main factors affecting the reliability and service life of electrical equipment. To address these problems, we herein develop dynamic cross-linked polyethylene materials (PE-MA-Epo) by polyethylene-graft-maleic anhydride (PE-MA) and polar epoxy monomers, which showed high ε_r (>7), low dielectric loss (<0.02), high U_e (5.16 J/cm³ at 425 MV/m), and outstanding discharge efficiency (97%). The performances of the materials are adequate to rival biaxially oriented polypropylene (BOPP) films. Moreover, the excellent self-healing capability of PE-MA-Epo enables the total recovery of ε_r and tan δ after electrical tree healing. After two cycles of electrical breakdown healing, E_b remained at 80%, which improves the durability and reliability of dielectric polymers. Therefore, PE-MA-Epo shows great potential for applications in advanced electronic power devices.