Researchers from the University of Eastern Finland have discovered that silicon can replace graphite in lithium-ion battery anodes without having to use nanoparticles. This could potentially quadruple a battery’s anode capacity.
Lithium-ion batteries, which are used in everything from smartphones to electric cars, have been deployed in data centers as part of Uninterruptible Power Supply systems, but still face an uphill struggle to overcome safety concerns.
Silicon has a theoretical specific capacity of approximately 4,200 milliamp Hours per gram for lithium, while carbon has only around 370 mAh/g.
Prior research has estimated that by changing the graphite anode (an electrode through which conventional current flows into a polarized electrical device) to a silicon one, cell energy density could be improved by 10–30 percent, when taking into account volumetric expansion.
It was previously believed that such gains could only be acheved using nanoparticles (which are hard to make, very expensive, and potentially unsafe). The key discovery in the University of Eastern Finland’s research paper, “Electrochemically anodized porous silicon: Towards simple and affordable anode material for Li-ion batteries,” was that particles between 10 and 20 micrometers are suitable for use in batteries.
“In our research, we were able to combine the best of nano- and microtechnologies: nano-level functionality combined with micro-level processability, and all this without compromising performance,” researcher Timo Ikonen said.
“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.”
Professor Vesa-Pekka Lehto added: “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.”