A graphic shows the structure of the silicon nanoparticles (L), and images of the particles captured at tiny scales (R). The research could lead to charge capacities ten times larger than current lithium ion batteries. Images courtesy of Jillian Buriak and Jonathan Veinot.
It always seems to happen at the critical moment-your phone battery runs perilously low. Scientists believe that silicon could be the answer to your battery woes, with the potential for a charge capacity 10 times larger than current lithium ion batteries. But while promising, silicon has the tendency to fracture and break with numerous charge and discharge cycles, due to volume expansion and contraction as silicon absorbs and releases lithium ions.
Now, University of Alberta chemists have published research that takes a critical step in solving this problem, studying the effect of nanostructuring the silicon within lithium ion batteries, to understand the importance of size.
"We wanted to test how different sizes of silicon nanoparticles could affect fracturing inside these batteries," explained Jillian Buriak, professor in the Department of Chemistry and Canada Research Chair in Nanomaterials for Energy. "As the particles get smaller, we found they are better able to manage the strain that occurs as the silicon 'breathes' upon alloying and dealloying with lithium upon cycling."
In a systematic investigation, the researchers examined silicon nanoparticles of four different sizes within highly conductive graphene aerogels. The results show that the smaller the particle, the less likely it is to crack or fracture upon lithiation. "The world is electrifying," said Jonathan Veinot, Professor of Chemistry and co-author on the study. "Imagine a car having the same size of battery as a Tesla, that could travel 10 times farther. Or, you charge 10 times less frequently, or the battery is 10 times lighter. The potential applications here are anything that relies upon energy storage using a battery."
The next steps, Veinot explained, are to develop technology for creating silicon nanoparticles in a faster and less expensive way, making these tools more accessible for industry and technology developers.
The paper, "Size and Surface Effects of Silicon Nanocrystals in Graphene Aerogel Composite Anodes for Lithium Ion Batteries," was published in Chemistry of Materials(doi: 10.1021/acs.chemmater.8b03198).