Researchers in Japan have created a high performance anode material for lithium ion batteries using waste silicon sawdust, a joint statement from Tohoku University and Osaka University said.
In a research study published in Scientific Reports, the research team from the two universities explained that they used high purity silicon discarded from the final cutting process of silicon wafer production to make anodes for lithium ion batteries.
High-grade silicon with a purity of nearly 100 percent is energy-intensive and expensive to produce, yet about 50 percent of it thrown away as scrap cuttings in the wafer production process. The silicon wafer industry worldwide produces about 90,000 metric tons of silicon waste annually, which the scientists said is an amount large enough to meet current global demand for lithium ion batteries.
To recycle waste silicon, the researchers pulverized the silicon into “nanoflakes” about 16 nanometers thick, then coated the fine powdery substance with carbon. The resulting mixture was then molded into a shape suitable for use as part of a battery.
The research report said that a test half-cell battery constructed using the material achieved a constant capacity of 1200 mAh/g over 800 cycles, a capacity 3.3 times larger than that of conventional graphite (approximately 360 mAh/g), which is the most common form of anode used now.
“The proposed method of material recycling is applicable for the mass production of high-performance lithium ion battery anode materials at a reasonably low cost,” the research team said. “We expect that it will have great practical use in the battery industry.”