Cross-Linked Poly(vinylidene fluoride-hexafluoropropylene)-graft-poly(glycidyl methacrylate) Achieved Enhanced Dielectric Properties and Charge-Discharge Efficiency

Poly(vinylidene fluoride) (PVDF)-based polymers are considered to be one of the most promising candidates for high-density capacitors. However, the practical application is limited by their low charge-discharge efficiency (η), which is ascribed to the high remnant polarization arising from the large hysteresis loss and conduction loss. In this work, we designed and prepared all-polymer-based dielectrics from cross-linking poly(vinylidene fluoride-hexafluoropropylene)-graft-poly(glycidyl methacrylate) (P(VDF-co-HFP)-g-PGMA, V-H-G) to address the issue. The bio-based amine of 2,5-bis(aminomethyl)furan (BAMF) was utilized to generate cross-linked networks through the amino-epoxy reaction. It demonstrated that the cross-linked structures, rich in polar groups and hydrogen bonding, could effectively tune the crystal properties and impede electrical conduction at high fields and elevated temperatures, resulting in restrained remnant polarization. An improved energy density of 7.39 J·cm^-3 at 450 MV·m^-1 for the cross-linked polymer was achieved, which was 648% of P(VDF-co-HFP) (V-H) (1.41 J·cm^-3 at 300 MV·m^-1) and 140% of V-H-G (5.18 J·cm^-3 at 400 MV·m^-1). Moreover, the η was significantly improved from 32% for V-H and 60% for V-H-G to 73.2% for the cross-linked polymer. Additional advantages of better dielectric properties at elevated temperatures compared with V-H and V-H-G were also observed. This work would provide inspiration for the design and preparation of high-performance polymer dielectrics.