High-dielectric PVDF/MXene composite dielectric materials for energy storage preparation and performance study

Abstract

Polyvinylidene fluoride (PVDF) has broad application prospects in the field of dielectric capacitors. However, the low dielectric constant of the polymer greatly limits the improvement of its energy storage density. In this paper, a highly conductive two-dimensional transition metal carbide (MXene) is utilized to modify PVDF by doping to prepare PVDF/MXene composite dielectrics, and a PVDF/MXene model is established based on molecular dynamics simulations to investigate the microscopic mechanism of improvement in the dielectric properties of the PVDF matrix upon doping. Finally, the effect of the MXene on the thermal conductivity and the mechanical and insulating properties of PVDF was investigated. The experimental results show that the relative dielectric constant of the PVDF/MXene-1.0 wt% system at 100 Hz reached 14.54, which is 55.96% higher than that of pure PVDF, and this doping amount or lower can reduce the dielectric loss of PVDF. In addition, MXene doping improved the mechanical and thermal properties of the composite material to a certain degree. When the doping amount of MXene was lower than 1.0 wt%, the electric breakdown strength of the composite system was maintained above 245 MV/m, which is sufficient to achieve good insulation strength under most conditions. Highlights: The low dielectric constant of polymers limits the improvement of their energy storage density. The doping of polymers with small amounts of conductive fillers can effectively increase the dielectric constant of the polymer matrix. A two-dimensional nanomaterial MXene is used to improve the dielectric properties of PVDF matrix and the micromechanisms are analyzed by molecular dynamics simulations. The key properties of PVDF/MXene, such as the mechanical properties, thermal conductivity and insulation, are characterized.