Preparing carbon black/graphene/PVDF-HFP hybrid composite films of high piezoelectricity for energy harvesting technology

Abstract Poly(vinylidene fluoride) (PVDF) and its copolymers with high piezoelectricity are of great interest for high efficient energy harvesting devices. In this study, carbon black (CB) and few-layer graphene (FLG) were added into one kind of copolymers of PVDF, i.e., poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) to fabricate hybrid composite films by the solution casting method. By adjusting the contents of CB and FLG, the relative fraction of β- phase increased dramatically, leading to a high piezoelectricity of the hybrid composite films. The maximum output voltage and the harvesting power density of the CB/FLG/PVDF-HFP films was 181% and 329% of the pristine PVDF-HFP films, respectively. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy analysis (FT-IR) and differential scanning calorimetry (DSC) were used to investigate the effect of hybrid fillers on the crystallization, mechanical stretching and poling process. Mechanical properties of the composite films were also measured. The dramatically enhanced piezoelectricity shows the great potential in energy harvesting devices.