I guess I don’t have to emphasize the importance of batteries in an electric car economy of the future. I also don’t have to tell anyone that many manufacturers pursue making ultracapacitors for their ability to quickly charge, discharge, and store a huge amount of energy – the perfect combination for an on-the-fly highway recharging.
One of the most important criteria in the functioning of an ultracapacitor is the dielectric (the piece of insulating material between the positive and the negative part of the capacitor). The dielectric has to withstand high voltages. Current performance bulk glass dielectrics can reach 4 to 9 Mega Volts (MV)/cm, meaning that 1 cm of dielectric can hold apart on one side and the other 9 million volts, for example.
Penn State University researchers discovered a bulk glass that can hold up to 12 MV/cm, and have a high permitivity, resulting in an energy density of 35 Joules/cm³, whereas standard polypropylene has only 10 J/cm³. Polypropylene is the most common dielectric in pulsed power applications.
Nick Smith, a Ph.D.in materials science and engineering at Penn state is the the lead author of the experiment. He used a commercial glass with a thickness of 50 micron that he thinned down to 10 to 20 microns by using hydrofluoric acid. The glass he obtained was so thin that it could be bent like a plastic film, but at the same time very delicate. The thinner the glass, the more electric field can be applied before it fails (and conducts).
The etched glass was placed in a polymer fluid for testing and up to 30,000 volts were applied. When the breakdown point was reached, electricity began to flow through the glass suddenly, with a flash and a bang that resembles a lightning bolt conducting through air. The polymer fluid was used to contain the lightning. In each case, failure occurred within 40 to 80 seconds.
The bulk glass the researchers tested is an alkali-free barium boroaluminosilicate used in large quantities for flat panel displays and microelectronics packaging. The very good energy storage capacity is due to the highly polarizable barium atoms, that also contribute to the high permitivity, and the alkali-free composition, inhibiting the energy loss. The more defect-free the glass is, the highest the energy the ultracapacitor can store.
The scientists are optimistic, saying that their defect-free barium boroaluminosilicate glass will be commercialized in the near future. It all depends on who is going to invest in their research. Maybe someone has to convince Warren Buffet, who is already investing in chinese electric cars. That way the bulk glass ultracapacitors will surely have a chance on the market.
After all, that’s life – it all depends on who’s investing trust in you. That should be something you should think about, if you didn’t. If you have the money, invest in these technologies, and bring them to the public, for your and everybody’s wellness.