Poly(vinylidene fluoride) terpolymer and poly(methyl methacrylate) composite films with superior energy storage performance for electrostatic capacitor application

Polymers with high electrical energy density and high dielectric performance are critical for advanced capacitor applications. Fluoropolymer dielectrics are potential candidate for capacitance energy storage applications because of their high dielectric constant. However, their dielectric loss tangent is high and the breakdown strength is low, resulting in undesirable low energy storage capability. Herein, polymer blend composites with improved energy storage capability were fabricated from poly(vinylidene fluoride-trifluoroethylene-chlorofluroethlyene) (P(VDF-TrFE-CFE)) and poly(methyl methacrylate) (PMMA). The blend composite with 15 wt% PMMA exhibits a high charge-discharge efficiency of 73% and a high discharged energy density of 9.3 J/cm3 at 520 MV/m, which is 172% higher than P(VDF-TrFE-CFE (5.4 J/cm3 at 270 MV/m) and 258% higher than the commercialized biaxially oriented polypropylene (BOPP) (3.6 J/cm3 at 600 MV/m)). The improvement in energy storage capability might be ascribed to the huge interaction between PMMA and P(VDF-TrFE-CFE) polymer chains, which leads to suppressed dielectric loss, small grain size, restricted leakage current density, and superior breakdown strength. This research provides new insights into designing high performance materials for dielectric and electrical energy storage applications.