A research group consisting of Associate Professor Hirotomo Nishihara and Professor Takashi Kyotani of the Institute of Scientific and Industrial Research, Tohoku University, Associate Professor Taketoshi Matsumoto and Professor Mitsuru Kobayashi of the Institute of Scientific and Industrial Research, Osaka University has been working on high-performance silicon chips from industrial waste. We have developed a method for recycling into negative material for lithium-ion batteries.
Lithium-ion batteries are widely used in mobile electronic devices such as smartphones and laptop computers, but in recent years they have also been installed in new models such as hybrid vehicles, electric vehicles, and fuel cell vehicles, and have energy density (storing power). There is a strong demand for further improvement in the amount that can be achieved.
Silicon wafers (semiconductor substrate materials) that are mass-produced generate almost the same amount of chips (silicon chips [Kiriko]) as the production volume, and are industrial waste.In this research, we found that if this silicon chip is crushed into thin nanoflakes, it can be used as a negative electrode material for lithium-ion batteries with high capacity and long life.Furthermore, this nanoflake-like silicon is compounded with carbon to further improve its performance and life, and it charges and discharges about 3.3 times the capacity (1200 mAh / g) of graphite used in conventional lithium-ion batteries. It was found that it can be maintained even if it is repeated 800 times or more.
The amount of silicon chips generated worldwide exceeds the global demand for lithium-ion battery negative electrode materials, making it an ideal resource.In addition to using industrial waste as a raw material, a simple method that can process even a large amount of silicon is used for crushing silicon chips into nanoflakes and subsequent compounding with carbon, and for lithium-ion batteries. It is expected to lead to the implementation of.
