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Tiny silicon particles could power lithium ion batteries with 10 times more capacity

University of Alberta chemists have taken a critical step toward creating a new generation of silicon-based lithium ion batteries with 10 times the charge capacity of current cells.

“We wanted to test how different sizes of silicon nanoparticles could affect fracturing inside these batteries,” said Jillian Buriak, a U of A chemist and Canada Research Chair in Nanomaterials for Energy.

Silicon shows promise for building much higher-capacity batteries because it’s abundant and can absorb much more lithium than the graphite used in current lithium ion batteries. The problem is that silicon is prone to fracturing and breaking after numerous charge-and-discharge cycles, because it expands and contracts as it absorbs and releases lithium ions.

The researchers examined silicon nanoparticles of four different sizes, evenly dispersed within highly conductive graphene aerogels, made of carbon with nanoscopic pores, to compensate for silicon’s low conductivity. They found that the smallest particles—just three billionths of a metre in diameter—showed the best long-term stability after many charging and discharging cycles.

[...] “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,” explained Buriak.

[...] The study, “Size and Surface Effects of Silicon Nanocrystals in Graphene Aerogel Composite Anodes for Lithium Ion Batteries,” was published in Chemistry of Materials.

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