High-performance energy storage technologies for the automotive industry or mobile phone batteries and notebooks providing long battery times – these visions of the future are being brought one step nearer to the present by scientists from Graz University of Techno- logy, in Austria.

Researchers at the Institute for Chemistry and Technology of Materials have developed a new method that uses silicon for lithium-ion batteries. The storage capacity is ten times higher than the graphite substrate that has been used until now, and promises considerable improvements for users. The new findings – which came to light in the European Union-sponsored NanoPoliBat project – were recently submitted to the patent office by researchers and their cooperation partner, Varta Microbattery. Modern electronic devices need more energy, and even the auto- motive industry is hankering after increasingly powerful energy storage systems. The technological development of battery research has been inadequate for some time now.

“A real revolution is needed for the deve- lopment of the next generation. We need new storage materials for lithium-ion bat- teries,” explains battery researcher Stefan Koller.

Together with colleagues from science and industry, Koller has managed to develop such a substrate material for electroche- mical reactions at a low price. In the newly developed process, researchers use a silicon-containing gel and apply it to the graphite substrate material.

“In this way, the graphite works as a buffer, cushioning the big changes in the volume of the silicon during the uptake and transfer of lithium ions,” explains Koller.

As silicon has a lithium-ion storage capacity some ten times higher than the hitherto commercially used graphite, the new material can store more than double the quantity of lithium ions without changes to the battery’s life.

“This method is far cheaper than the existing ones, in which silicon is separated in the gas phase.
“The challenge lies in the poor storage density of materials in the counterelectrode in the whole battery, something which we have been doing intensive research on,” says Koller. The use of molecules as elements in electronic circuits shows great potential. One of the central challenges until now has been that most molecules only start to conduct electricity once a large voltage has been applied.

An international research team con- sisting of researchers from Graz University of Technology; Humboldt University, in Berlin; the Massachusetts Institute of Technology; Montan University, of Leoben; and the Georgia Institute of Technology has shown that molecules containing an odd number of electrons are much more conductive at low bias voltages.

These fundamental findings in the highly dynamic research field of nanotechnology open up a diverse array of possible applications. More efficient microchips and components with considerably increased storage densities are conceivable.