When individual silicon wafers are cut from larger
sheets of silicon for use in electronics, a lot of sawdust is
produced. Ordinarily, that material is simply discarded. Thanks
to research currently being conducted by Japan's Tohoku
University and Osaka University, however, it may soon find its
way into high-performing lithium-ion batteries.
The scientists started with regular silicon sawdust,
washed it to remove impurities (such as coolant) that were
introduced in the sawing process, then pulverized it into porous
and wrinkly "nanoflakes" measuring about 15 nanometers thick.
Those flakes were subsequently coated in carbon, then
incorporated into battery anodes.
When tested, a lithium-ion half-cell using one of
those anodes achieved a constant capacity of 1,200 mAh/g
(milliamp hours per gram) over 800 cycles. While that might not
mean much to the layperson, that capacity
is reportedly 3.3
times larger than that of a comparable conventional graphite
anode.
According to the researchers, the recycling process
should be easy to scale up for mass production, plus costs of
the anodes ought to be reasonably low. Additionally, they
estimate that the amount of silicon sawdust generated worldwide
every year should be enough to meet global demand for anode
materials.
A paper on the study was recently published in the
journal
Scientific Reports.