From silicon waste to batteries
We have demonstrated and advocate the up-cycling of Si nanoparticles from wafer slicing waste to Li ion batteries.
A large amount of silicon debris particles are generated during the slicing of silicon ingots into thin wafers for the fabrication of integrated-circuit chips and solar cells. This results in a significant loss of valuable materials at about 40% of the mass of ingots. In addition, a hazardous silicon sludge waste is produced containing largely debris of silicon, and silicon carbide, which is a common cutting material on the slicing saw. Efforts in material recovery from the sludge and recycling have been largely directed towards converting silicon or silicon carbide into other chemicals such as SiCl4, SiO2, SiC, or Si3N4, which requires extensive chemical processing steps that are often costly. Moreover, these recycling strategies merely use silicon sludge waste as a source of the Si element, and do not fully take advantage of the nanoparticle form factor of Si and its high purity.
Si wafer slicing waste is mostly Si nanoparticles, which can be directly harvested by an aerosol approach to make Li battery materials.
In collaboration with Dr. Hee Dong Jang from KIGAM, South Korea, we demonstrated that silicon nanoparticles can be extracted from such sludge wastes and then directly used for lithium ion battery applications. Using an ultrasonic spray-drying method, silicon nanoparticles can be directly recovered from the mixture, making them readily usable for making lithium ion battery anode. It upcycles wafer slicing wastes into much higher value-added materials for energy applications.