Researchers make silicon anode breakthrough

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Using a new method to probe silicon batteries, researchers at the University of Cambridge have made a breakthrough in understanding what happens when silicon is used as the anode material in a lithium battery.

Developers have been working for many years on ways to incorporate silicon anodes in lithium based batteries because they can store roughly 10 times more charge than their carbon based counterparts. However, silicon atoms absorbs lithium atoms, expanding by up to three times in volume and degrading the battery in the process. A lack of understanding of the process is said to be holding back the development of silicon based batteries. Using nanoscale wires made of silicon and nuclear magnetic resonance (NMR) techniques, the researchers developed a model system capable of accommodating the expansion of silicon over multiple cycles. This was integrated with probing techniques that reveal what is happening inside the battery at the atomic level. This allowed the team to develop a 'map' of how silicon transforms when in contact with lithium in a battery. "Using this technique will help make battery design much more systematic and less trial and error," said Dr Ken Ogata from the University's Department of Engineering. "The nanowire based batteries, coupled with the NMR system, enabled us to follow the reaction kinetics over multiple cycles with various cycling strategies. Importantly, the insights achieved by the new technology are relevant to current state of the art silicon-carbon composite anodes and will lead to further development of the anodes." pic: Argonne National Laboratory via Flickr