Poly(vinylidene fluoride)-Based composites modulated via multiscale two-dimensional fillers for high dielectric performances

Ultrathin two-dimensional (2D) semiconductor molybdenum disulfide (MoS₂) nanosheets have wide applications in electronic devices. Incorporation of MoS₂ nanosheets into poly(vinylidene fluoride) (PVDF) renders a type of dielectric composite regulated with 2D architecture. However, due to the semiconducting behavior of MoS₂, the accompanying high dielectric loss prevents the composite being good dielectrics. Aluminum flakes (AFs), another 2D structure in micron scale, were thus introduced into the MoS₂/PVDF composite to block leakage path as well as providing another source for electric polarization. The effects of multiscale 2D fillers on adjusting the dielectric and electrical properties of the ternary MoS₂/AFs/PVDF composites were investigated systematically. The largely suppressed dielectric loss and electrical conductivity of ternary composite compared with those of MoS₂/PVDF composite is ascribed to the parallel arranged self-passivated AFs, which effectively inhibit the direct connection and overlapping of MoS₂ nanosheets along the electric field direction. Meanwhile, formation of numerous micro-capacitors with AFs as electrodes and MoS₂/PVDF composite as dielectric medium makes an additional contribution to the high dielectric constant of the ternary composite. Furthermore, the dielectric polarization and relaxation process of composites were investigated in terms of electric modulus to explain the variation tendency of dielectric and electric property of the composites.