Most modern electronic devices owe their existence to silicon (Si), an abundant element whose material properties have enabled technologies such as microprocessors, solar cells, and fiber optic cables.
Such applications, however, require varying degrees of highly purified Si, currently produced by complex, expensive, and environmentally unsound processes.
Researchers describe in the journal Nature Communications a low-cost nanopurification process that yields 99.999% pure Si from ferrosilicon, an inexpensive and widely available silicon–iron alloy.
The process uses a high-energy ball mill to crush ferrosilicon pieces into nanoparticles. Because impurities in the ferrosilicon represent structural weak points, ball milling fractures the alloy at regions with impurities and exposes them to the surface. The impurities are then stripped away with an acid treatment, leaving behind purified Si nanoparticles.
As an example, the authors also demonstrate that Si nanoparticles purified in this manner can be used as anodes in high-performance rechargeable lithium ion batteries.
The findings represent a commercially viable and cost-effective procedure for recovering purified Si from low-quality material, according to the authors.