When Andre Geim and Konstantin Novoselov received the Nobel Prize in Physics for their research on graphene, recognition went beyond the material itself. The award specifically mentioned «the two-dimensional material graphene», highlighting the importance of the two dimensions in the discovery. Perhaps the jury wanted to emphasize the importance of the research that proved the possibilities of a new way of structuring materials.
Graphene is composed of pure carbon atoms, laid out in a hexagonal shape. This structure comes in sheets, that is, a two-dimensional plane. But, though this material is the first to have gained notoriety for this reason, it is not the only one. Another material that is likely to become a key element for the technology industry in the coming years is silicene.
The first silicene structures were observed on silver crystal and their form was hexagonal, similar to that of graphene, although not entirely flat. Recently, joint research between scientists from the Technical University of Berlin and the University of Aix Marseille created isolated silicene by condensing silicon vapour on silver.
This breakthrough opens the way for experimentation with silicene, which until now had been limited to speculation, on a more or less solid scientific basis. Researchers have found that silicene sheets meet the properties expected of them. The next step is to combine the substance with insulating materials to verify their benefits in electronic devices.
A boost for batteries
Pending further verification in the laboratory of silicene’s properties in association with insulating compounds, we have to settle for theory as our most accurate source of knowledge on the material. One of the most striking applications is related to its use in lithium ion batteries, the most common in the electronics industry.
Silicene is very strong, like graphene, and that makes for good performance in the anodes of lithium-ion batteries. This feature alleviates volume changes that occur during charging, approaching the margins offered by graphite, the material that is currently used.
However, silicene has a differential value over graphite. It offers twice the capacity for the anode and its strength also prevents it suffering changes during charging and discharging. This means that batteries made with this material would have a much longer life than we are used to now, and would not progressively degenerate as they do today.
These conclusions were obtained from investigations with silicon nanostructures (such as nanowires), not silicene. So they are only theoretical. Commercial usage is still far off; first, experiments must be conducted with the new material, followed by evaluations to determine if it really meets expectations. Then, a sustainable production model must be found.
Much research is being carried out to improve the batteries that give autonomy to a large mass of electronic products. In some of them silicon plays a leading role. Here is a material that offers the hope of highly optimized performance, as demonstrated by a team from Kansas State University, who combined it with carbon and obtained devices capable of accumulating up to 10 times more electricity than today’s devices. But perhaps silicene will sweep away these experiments.
In the wake of graphene
But let us not get carried away by enthusiasm, as we did with graphene after the Nobel Prize and new research on its properties appeared. Despite everything that has been said about it, the carbon derivative has no commercial uses and there is no manufacturing industry worldwide, although Spain takes the lead in this area, with several companies selling internationally.
Graphene is not taking off as fast as the general expectations initially led us to believe. Experimentation with silicene will arrive soon and both materials could rival to revolutionize some components of the electronics industry. The main advantage that the former has over the latter is the time spent on it.
Despite graphene being far from a commercial reality, experimentation with the material has been intense in recent years, both by research centres and by companies. Silicene has yet to travel along this route, though this does not imply that both compounds are interchangeable.
Image: Manu gomi
