The study analysed the suitability of electrochemically produced nanoporous silicon for Li-ion batteries. It is generally understood that in order for silicon to work in batteries, nanoparticles are required, and this brings its own challenges to the production, price and safety of the material. However, one of the main findings of the study was that particles sized between 10 and 20 micrometres and with the right porosity were the most suitable ones to be used in batteries. These micrometre-sized particles are easier and safer to produce from new sources than nanoparticles and helps with recyclability.
Several startups are already manufacturing batteries using silicon anodes.
"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," said 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."
The researchers will also combine silicon with small amounts of carbon nanotubes in order to further enhance the electrical conductivity and mechanical durability of the material with new sources of silicon and carbon.
"We now have a good understanding of the material properties required in large-scale use of silicon in Li-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," said Professor Vesa-Pekka Lehto at the university.