Dielectric vehicles?

A wonder battery is turning poor conductivity into a positive by sending electric cars further and faster for longer.

Researcher holds flexible dielectric polymer. Insert shows boron nitride nanosheets. (Qing Wang/Penn State)

The material it is made from is a polymer dielectric material which means it has poor electric conductivity but it an efficient supporter of electrostatic fields making it useful for storing energy in vehicles.

A polymer dielectric material with high energy density, high power density and excellent charge-discharge efficiency for use in electric and hybrid vehicles has been developed. Dielectric material has poor electric conductivity, but is an efficient supporter of electrostatic fields, which can store energy.

Increased efficiency in energy storage for electric and hybrid vehicles is the major aim of battery research scientists. More power, storage capacity and reduced charge times are key to the success of low-cost electric vehicles when their performance is compared to cars powered by fossil fuels.

The work, by a team of researchers at Penn State University, was supported by the US Office of Naval Research. Lead author Dr Qi Li described the material as a sandwich-structured polymer nanocomposite based on cross-linked divinyltetramethyldisiloxane-bis(benzocyclobutene) (c-BCB), boron nitride nanosheets (BNNSs) and barium titanate nanoparticles (BT NPs). “The new design is that BNNSs and BT NPs are spatially arranged in the c-BCB polymer in a sandwich structured-fashion. The BNNSs located in the outer region serve as efficient barriers against charge injection and thermal activation of electrons, and BT NPs sitting in the central region improve the dielectric polarization. As a consequence of the combined effects, the polymer nanocomposites exhibit exceptional performance in terms of excellent high-temperature and high-electric field dielectric reliability and capacitive energy storage.”

The material has been specifically designed for high-temperature film capacitor applications that are critical in a broad range of power electronics and systems ranging from electric vehicles through aerospace power conditioning to military weapon systems.

“In the past two years we have made substantial progress on this project regarding high-temperature polymer dielectrics,” revealed Dr Li. “We have got very encouraging results from the new materials and approaches developed in our lab. Now we are working on extending these novel concepts and designs to a general level, and also are seeking for the possibility of large-scale production of the materials.”

DR Li told Materials Science that the new design and concept has meant the material has achieved a performance level much greater than other materials. “But of course there is room for further improvement. I believe these exciting results will help to spur the development and engineering of new materials enabled by collective efforts from the whole community.”

Commercialization of these materials is the ultimate goal of the research, but depends on a the cost of the raw materials, the availability of an economical production method, and the compatibility of materials with existing device fabrication techniques.