Use silicon for energy storage

09/08/2017 | Print view

Battery cells with silicon anodes could store up to ten times more energy than the previous cells with graphite anodes. - © Christian-Albrechts-Universität Kiel — © Christian-Albrechts-Universität Kiel

Battery cells with silicon anodes could store up to ten times more energy than the previous cells with graphite anodes.

The concept of a silicon battery already exists. But the mechanical problems still have to be solved. Researchers from the University of Kiel and the equipment manufacturer Rena Technologies are collaborating to develop a market-ready product, that can store up to ten times more energy.

The researchers at the Institute of Materials Research at the University of Kiel and Rena Technologies want to bring the silicon battery to market. "The whole renewable energy sector is waiting for a better battery," says researcher Jürgen Carstensen. The silicon battery can be better because it is made up of cheaper materials and, above all, because it can store more energy.

Solve the problem of extension

The concept of the silicon battery is already on the table. The approach is to replace the graphite anodes of conventional lithium-ion batteries with silicon. The material is considered as promising, it can still store up to ten times more energy than the graphite anodes. "Theoretically, silicon is the best material for anodes in batteries, but there are numerous problems with it," says Sandra Hansen, director of the Kiel University. Up to now, the semiconductor material has not yet been mechanically stable enough to be used in current energy storage devices. This reduces the lifetime of the silicon anodes. This is mainly due to the fact that the anodes expand extremely strongly during landing - at least 400 times their initial size. There is therefore a risk that the anode will break.

Anodes entirely made of silicon

The Kiel scientists want to solve this problem and thus to increase the silicon proportion of the anode material. So far, it is just five percent because of the extension factor. The ultimate goal is to produce anodes completely from silicon. In addition, Sandra Hansen has further developed a method from the solar sector to improve the quality and functionality of the silicon layers in the battery. The researchers want to produce the counterpart, the cathode, from sulfur. "A sulfur cathode offers the maximum possible storage capacity," Hansen says. "In this project, we combine two materials that promise a really high performance of the battery." (HCN)