Waterborne Nanocomposites with Enhanced Breakdown Strength for High Energy Storage

Polymers have been considered as promising materials for dielectric energy storage because of their high breakdown strength, favorable flexibility, and processability. The achievable energy density of polymers is, however, limited by their intrinsic low dielectric constant. Until today, most of them are either melt-extruded at high temperatures or solution-processed in harmful organic solvents. Making high-energy polymeric dielectrics in an environmentally friendly manner has been a long-standing challenge. Herein, a water-based technique is employed to prepare all-polymeric dielectrics consisting of poly(vinylidene fluoride) (PVDF) latex nanoparticles dispersed within a poly(vinyl alcohol) (PVA) matrix. These waterborne nanocomposites, processed at low temperature, demonstrate great promise in resolving the paradox between the dielectric constant and the breakdown strength. A high energy density of 8.1 J/cm3 is thus achieved at ∼515 MV/m, which is 300% greater than that of each polymer component. Moreover, with an appropriate load resistance, the nanocomposite can release the stored energy at a rate of microseconds, giving rise to a power density of 1.13 MW/cm3 that is nearly 400% higher than that of benchmark biaxial oriented polypropylene dielectric films.