Conventional chemical batteries suffer from a number of disadvantages. The recharging of the battery can result in excessive heating and gassing, and overcharging can reduce the battery’s life. Charging also results in a gradual decrease in the battery’s efficiency.
Even solar batteries that promised to be better alternatives are now regarded as relatively inefficient, since they produce electricity only with sunlight. Other traditional materials such as ceramics also fall short of current technology needs as they are heavy and fragile.
In this regard, Qing Wang and researchers at Penn State University have developed ferroelectric polymer-based capacitors that are capable of delivering power more rapidly than conventional batteries. The new polymers and polymer nanocomposites are characterised by high energy densities and are well suited for electrical storage applications.
The research group developed a polymer of polyvinylidene fluoride and trifluoroethylene, which, when combined with chlorotrifluoroethylene, was found to exhibit very high electric permittivity at room temperature. By further altering the amounts of the added chemical components, the dielectric property and energy density was modified.
The team also succeeded in combining the polymer with nanoparticulate ceramics, which further increased the electric permittivity and storage capacity. The incompatibility between the ceramic particles and the polymer matrix was overcome by attaching appropriate functional groups to the materials. Proper mixing was also carried out so as to ensure complete dispersion within the matrix.
Compared to ceramics, these polymer materials can be easily processed, are lightweight, have higher breakdown strength and are cheaper. Apparently the achieved electric density of approximately 17 J/cc is higher than polypropylene, the polymer that is currently being used in commercial capacitors and which delivers approximately 2 J/cc. The technology also boasts new scalable preparation methods with precisely controlled chemical compositions, energy densities and dielectric properties.
“This development could impact many areas such as memory and gate dielectrics for integrated circuits in advanced electronic devices, stationary power generation, miniature capacitors for telecommunication, and hybrid electric vehicles,” Wang says.
He adds that many advanced application needs are likely to be fulfilled by these materials. However, further research has to be carried out so as to enhance the stability and reproducibility of these materials, in addition to developing scalable processing methods for polymer nanocomposites with controllable dielectric properties.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)21 680 3274, [email protected],
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