For present ceramic particles/polymer dielectric composite materials, their dielectric properties and thermal conductivity haven't met the application requirement at the same time. In this research, to achieve this goal, barium titanate@super short MWCNTs (BT@SSCNT) core-shell particle was prepared in a confinement reactive space built by water phase and oil phase. Polyvinylidene fluoride (PVDF) based composite flexible films reinforced by the BT@SSCNT particles possessed desired dielectric and excellent thermal behaviors. Especially for the composite film with 60 wt% (containing less than 17 wt% SSCNT) loading, at 10 2 Hz and in the wide temperature range of −40–140 °C, dielectric constant and dielectric loss varied from 476 to 764 and from 2.74 to 4.58, respectively. Meanwhile the thermal conductivity of this film reaches 25.43 W/(m K). The promising dielectric properties and high thermal conductivity of the films are attributed to multiple roles of SSCNT shell layer including external electric field applying on BT particles, tremendous interfacial polarization area, restricted electron motion and electron efficient in transporting heat. The BT@SSCNT/PVDF composite films can be a promising candidate for the modern electronic industry.
Flexible dielectric energy storage capacitors have important application potentials in pulsed power systems. However, low energy storage density has always been an obstacle to practical applications because it is difficult to increase the dielectric constant of flexible dielectrics while reducing dielectric loss. In this study, a strategy is proposed to solve this problem. As the filler of polyvinylidene fluoride (PVDF), a special inorganic core–shell structure is constructed. The core–shell filler structure includes a donor Y-doped BST core and acceptor Mn-doped BST shell, wrapping ZrO2 as the outermost layer (Y@M-BST@ZrO2). Through this design, the simultaneous optimization of dielectric constant and dielectric loss is finally realized in the BST/PVDF composites. When an electric field is applied, the separation of electrons and holes formed in the core–shell fillers Y@M-BST@ZrO2 enhances the composite polarization and dielectric constant of Y@M-BST@ZrO2/PVDF and meanwhile reduces its dielectric loss at 1 kHz; therefore, the composite energy storage properties are significantly improved in comparison with the sample BST@ZrO2/PVDF. In experiments, the Y@M3-BST@ZrO2/PVDF composite film has a dielectric constant of 20.9, a dielectric loss of 0.024, and an energy storage density of 7.555 J/cm3 at 600 kV/cm, which is 74.6% higher than that of BST/PVDF composite film. It reaches 2.1 times the energy storage density of pure PVDF film. This study shows that the formation of a polarization structure caused by a positioning doping in core–shell structural fillers may provide a path for functional dielectrics of high-energy-density capacitors.
Xiao Li,Chongxiao Yuan,Hengqing Zhou,Guoqi Gao,Jia He,Xiang Liu,Yuanhui Li,Huajun Sun,Xiaofang Liu
The transformation of environmentally benign waste energy into functional electricity holds profound implications for advancements in human progress. Herein, we detail the synthesis of tubular nanofibers featuring a hollow architecture through an innovative combination of sol-gel processing and electrospinning techniques , followed by surface modification with dopamine. These engineered PZT hollow nanotubes , upon integration into PVDF piezoelectric films, serve as potent reinforcing agents that amplify the piezoelectric active phase within the PVDF matrix. The introduction of these hollow PZT nanostructures alters the polarization electric field distribution, thereby augmenting the polarization dynamics of PVDF and significantly enhancing the piezoelectric performance of the resultant PVDF/PZT composite films . Our novel nano-generator exhibits an exceptional balance between a high piezoelectric coefficient , superior output characteristics, and commendable stability. Notably, the piezoelectric constant ( d 33 ) of Neat PVDF films experiences a substantial elevation from 9 pC N −1 to 20 pC N −1 , representing an impressive enhancement of approximately 122 %. Furthermore, the power density achieves a value of 0.54 μW cm −2 . This study introduces an effective approach to augment the productive output capability of composite nanogenerators, paving the way for sustainable energy harvesting technologies.
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