Researchers create lithium-ion battery with ten times the energy capacity

Researchers at the German University of Kiel are developing a lithium-ion battery in which the anode consists entirely of silicon. According to the scientists, this leads to an energy capacity that is up to ten times that of regular lithium-ion batteries.

According to the researchers, silicon as a material has the highest energy density in relative terms and is therefore theoretically very suitable for batteries. However, the stability of silicon has been a problem until now; when a large amount of lithium ions is absorbed, the material expands by 400 percent, which could cause it to break. The researchers believe that this problem can be solved by applying the silicon in the form of very thin wires.

Research shows that silicon behaves much more flexibly when it is produced in the form of a thin wire. That principle is applied to porous silicon. The silicon is provided with nanopores in the microstructure, so that there is more free volume and more room to expand. To prevent the anode’s contact points from breaking, the researchers have developed a method for a stable connection between the two. The cathode is made of sulphur, which, like silicon, has a high energy storage capacity.

To further extend the life of the silicon anodes, they must be produced by means of a wafer. For example, it is possible to map irregularities in the surface of the wafer; these imperfections limit the performance of the anode.

For the time being, there are no batteries based on this technology on the market. The researchers acknowledge that the described process takes a long time and is very expensive. A prototype should be ready in three years. If such a lithium-ion battery based on silicon becomes a reality, it will not only last much longer, but also be charged much faster than current lithium-ion batteries.