Researchers at the Korea Institute of Science and Technology (KIST) in South Korea have developed a technique to significantly improve the performance of silicon anode battery cells. This could boost the capacity of a fast charging battery cell by four times for higher range in electric vehicles.
Many companies are working on silicon anode materials for batteries with up to ten times higher capacity and faster charging than today's lithium ion cells. However silicon anodes can swell in size when charging. Nexeon in the UK has been leading development of silicon anode technologies, while Varta recently announced it would be investing heavily in the technology in Europe. Group 14 Technologies is also scaling up production of a carbon silicon anode material.
The technique developed by Dr. Hun-Gi Jung and his team at the Centre for Energy Storage Research at KIST enable rapid charging to more than 80 percent capacity in only five minutes and in batteries for electric vehicles could double the driving range.
Jung and his team dissolved corn starch waste in water and silicon in oil, then mixed and heated them in order to produce carbon-silicon nanospheres. A simple thermal process used for frying food was used to firmly fix the carbon and silicon, preventing the silicon anode materials from expanding during charge and discharge cycles.
At 1,530mAh/g the composite materials showed a capacity four times that of graphite anode materials (360mAh/g) and was stable over 500 cycles. It was also found that the materials enable batteries to charge to more than 80 percent capacity in only five minutes. The carbon spheres prevent the usual volume expansion of silicon, enhancing the stability of silicon materials and the highly conductive carbon and the rearrangement of the silicon structure resulted in a high output.
"We were able to develop carbon-silicon composite materials using common, everyday materials and simple mixing and thermal processes with no reactors," said Jung.