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.
Source: Tohoku University