This photo shows the novel silicon material developed as an anode for lithium-ion batteries. Photo: Timo Ikonen.
This photo shows the novel silicon material developed as an anode for lithium-ion batteries. Photo: Timo Ikonen.

Silicon – the second most abundant element in the earth's crust – shows great promise in lithium-ion batteries, according to a team of Finnish researchers. They found that the capacity of the anode in these batteries can be quadrupled by simply replacing graphite with silicon.

In a climate-neutral society, renewable and emission-free sources of energy, such as wind and solar power, will become increasingly widespread. The supply of energy from these sources, however, is intermittent, and technological solutions are needed to safeguard the availability of energy when it's not sunny or windy. Furthermore, the transition to emission-free energy sources for transportation also requires specific solutions for energy storage, and lithium-ion batteries are considered to have the best potential.

Researchers from the University of Eastern Finland and Aalto University have now introduced a new technology to lithium-ion batteries, by replacing conventional graphite anodes with versions made from silicon, specifically electrochemically produced nanoporous silicon.

It is generally understood that making silicon work in batteries requires nanoparticles, which brings a range of challenges in terms of production, cost and safety. However, one of the main findings of the study was that particles of 10–20µm in size and with the right porosity were in fact the most suitable ones to be used in lithium-ion batteries.

This discovery is significant, as micrometer-sized particles are easier and safer to process than nanoparticles. It is also important from the viewpoint of battery material recyclability, among other things. The researchers reported their findings in a paper in Scientific Reports.

"In our research, we were able to combine the best of nano- and micro-technologies: nano-level functionality combined with micro-level processability, and all this without compromising performance," says researcher Timo Ikonen from the University of Eastern Finland. "Small amounts of silicon are already used in Tesla's batteries to increase their energy density, but it's very challenging to further increase the amount."

Next, the researchers will combine silicon with small amounts of carbon nanotubes in order to enhance further the electrical conductivity and mechanical durability of the material.

"We now have a good understanding of the material properties required in large-scale use of silicon in lithium-ion batteries. However, the silicon we've been using is too expensive for commercial use, and that's why we are now looking into the possibility of manufacturing a similar material from agricultural waste, for example from barley husk ash," explains Vesa-Pekka Lehto, a professor at the University of Eastern Finland.

This story is adapted from material from the University of Eastern Finland, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.