Achieving high energy density and efficiency concurrently in BNNS/P(VDF-HFP) composites via synchronous heating and stirring treatment

To meet the rising demand for energy storage, it is essential to achieve further improvements in the energy storage density and efficiency of composites based on dielectric polymers. Herein, Boron nitride nano sheets (BNNS) with high breakdown strength and high thermal conductivity was introduced into the matrix of polyvinylidene fluoride hexafluoropropylene (P (VDF-HFP)). Via synchronous heating and stirring treatment, BNNS were well dispersed in P(VDF-HFP) with increased fluidity due to the rise of temperature. With the incorporation of 7 wt% BNNS, the composite achieved high energy storage density of 21 J/cm3 at 492 MV/m and high efficiency of 80.2 % concurrently, outperforms most previous polymer-based composite dielectric energy storage materials. This is attributed to the fact that BNNS can induce the formation of P(VDF-HFP) crystalline phase, and the simultaneous heating process improves filler dispersion to extend the breakdown path and disperse electron heat accumulation.