All-solid dielectric founded capacitors are most promising since they display superior advantages such as fast charge speed, distinct high power densities, environmentally friendly characteristics and long cycle life. Energy storage applications of polymer based or ceramic dielectrics is limited to specific conditions due to their low energy densities as compared to the main marketable twin layered capacitors or batteries. This has sparkled investigative innovation on dielectric materials for energy storing applications. Nanoparticle fillers have since been utilized to improve electric polarization of polymer matrix owing to their exemplary overall performance. However, high loading of commonly applied fillers lead to severe reduction of their breakdown strength of the composite dielectric , which results in degraded energy density.
Yanan Hao and colleagues proposed a method to enhance the energy storage performance of capacitors significantly by using ultimate sized ferroelectric BaTiO3 fillers in nanocomposite films. Their main aim was to reduce dielectric deterioration and minimize impeding of energy density by the high polarization and dispersibility of the particle fillers. Their work is now published in the journal Nano Energy.
Foremost, the research team prepared nano-powders by an original one-step TEG-sol method. A mixture of the BT nanocrystals and the polymer was dispersed and sonicated in a solvent until they formed a yellow transparent nanocomposite solution. These was used to generate nanocomposite films and pure BT nanocrystal film by spin coating the mixture on a Pt coated silicon substrate and subsequently baking them on a hot plate for thirty minutes. They measured the ferroelectric polarization switching image and the hysteresis loop of the nanocrystals. Dielectric measurements of the nanocomposite films were then performed using a high-performance frequency analyzer at an accelerating voltage of 200 kilovolts.
The research team observed that ferroelectricity of the nanofillers used gradually declined as the particle size decreased. The high dispersability of the particles observed was credited to the presence of triethylene glycol on the coating layer of the nanocrystals.
Average sized nanocrystal fillers with a well dispersability were observed to bebeneficial in enhancing dielectric properties and improving energy storage capability of the poly (vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) based nanocomposite film. Their low permittivity, related nanoscale defect size and small crystal size were seen to play part in alleviating field intensification and promoting high dielectric homogeneity. This significantly enhanced their breakdown strength hence improving the energy density of the nanocomposite.
The self-assembly effect and well dispersability of the nanocrystals promote fabrication of microscopically dense and homogeneous structures. This approach open new avenues that can provide a new type of filler material for the enhancement of organic-inorganic nanocomposites. It also sheds light for further exploration and production of nanocomposites of high energy densities.
Yanan Hao1, Xiaohui Wang2, Ke Bi1, Jiameng Zhang1, Yunhui Huang3, Longwen Wu2, Peiyao Zhao2, Kun Xu1, Ming Lei1, Longtu Li2. Significantly enhanced energy storage performance promoted by ultimate sized ferroelectric BaTiO3 fillers in nanocomposite films. Nano Energy volume 31 (2017) page 49–56.Show Affiliations
- State Key Laboratory of Information Photonics and Optical Communications & School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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