The technology involves coating lithium-ion (li-on) batteries with silicon powder. This greatly increases performance -- almost ten times the "energy capacity per gram", the company claims. It would mean either much smaller batteries or much longer life. They could be used in mobile phones and also in electric vehicles and other applications.
The key, apparently, is something called sub-micron "pillared particles". When li-on batteries are charged the lithium migrates into the silicon. As the power is used it migrates back out. This places a strain on the silicon, causing cracking and poor performance. By using powder the cycle life is greatly improved.
Nexeon was formed in 2006 as a spin-off company by Imperial Innovations, who commercialise work by Imperial College. The technology was based on Professor Mino Green's work. He was listening to a lecture where it was stated that silicon was theoretically superior to graphite but that the large volume expansion that silicon would undergo would block its use. He thought then of the pillared particles concept.
This is a list of 9 World patent applications in the name of Nexeon which mention silicon in the abstract, all published since 2008.