Better charge storage and faster discharges could make better batteries.
It might seem like a defibrillator and a hybrid car have very little in common, but researchers from the UShave developed a material that could have a profound effect on them both.
Qiming Zhang and his colleagues at Pennsylvania State University, University Park, US, have developed an insulating polymer that can store large amounts of electrical charge in a small space. Crucially, the polymer can also discharge this electricity in less than a microsecond. Previously, higher energy storage has gone hand in hand with slow discharge, and vice versa.
Capacitors loaded with the polymer could become the basis for smaller, more efficient batteries for hybrid cars, or generate the sudden electric discharge needed to restart hearts.
The polymer molecules are a combination of two molecular units: vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE). This combination makes the polymer dipolar, so that some parts of the molecule is naturally loaded with more electrical charge than the other.
Once the polymer is fully charged, a jolt of electricity can realign the polymer molecules so that like charges are brought closer together, which triggers the discharge.
’This is a totally new approach. We have been able to design a polymer that can be rapidly modified with electric energy,’ said Zhang. ’Our idea suggests that if you increase level of polarization change that you can cause, you can get more energy out of the capacitor very quickly.’
While polymers are already the materials of choice for energy storage, due to their reliability and low cost, Zhang claims that the work could open up a new field for research into materials for capacitors.
’The very high electrodensity of this material could easily be applied to microelectronics and the development of even smaller hand-held devices,’ he said.
B Chu et alScience, 313, 334