Promising research into silicon batteries

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Elkem’s research department has been continuously charging and discharging a silicon test battery since September 2014. The results so far are promising: the capacity of the battery is more than that of current lithium batteries.

The more efficient the battery, the more useful electricity becomes as an energy source. Silicon for batteries could be a large market for Elkem. If this is achieved, as most people believe it will be, this could be a market in which Elkem could deliver thousands of tonnes a year. More efficient batteries will also make solar energy, which is one of Elkem’s most important ventures, more useful.

Special silicon

Elkem is carrying out research into developing the silicon material that works best in batteries. Elkem currently sells special silicon, Silgrain® e-Si, produced at the plant in Bremanger. Customers use Silgrain® e-Si in battery tests, or in silicon/lithium batteries. The watchmaker Breitling is one of the companies that have started using such batteries. Silgrain® e-Si was developed in collaboration with a Japanese research centre, AIST Kansai.

In theory it will be possible to increase battery capacity tenfold by using silicon as the anode. The problem with silicon, however, is that it expands 400 per cent when it reacts with lithium during discharge. This can lead to the pulverisation of the anode, meaning the battery cannot be recharged.

Silicon and graphite

Elkem has its own divisions of specialists on both carbon and silicon that, together with the Institute for Energy Technology (IFE) and SINTEF have tried to find mix proportions with silicon that can withstand enough charging cycles for it to be used in, for example, a car. Gluing together microscopic particles of silicon and graphite leaves enough room in the structure for the silicon elements to expand and contract without the sub- stance being pulverised.

In 2015 Elkem Technology will conclude a three-year research project into the use of silicon as the anode in lithium batteries. Ongoing tests indicate that the new anodes more than double the storage capacity of lithium batteries compared to today’s graphite anodes.