Domestic and international researchers, including Professor Park Soo-jin (CHEM) and Rodney S. Ruoff, Director of the IBS Center for Multidimensional Carbon Materials, developed a silicon material for fast-charging lithium-ion batteries. It was confirmed that, when used as the anode of the battery, the new silicon material charged five times faster than the conventional battery, increased the battery capacity by more than double, and maintained a stable structure even after repeated charging and discharging.
Graphite, the material currently used for the anode in electric car batteries, has its limits in that its theoretical capacity is limited and that it deposits lithium on the surface of the anode, thereby deterring the performance and the stability of the battery. Therefore, having a capacity of 10 times bigger than that of graphite, silicon was the next candidate for the anode material. However, silicon’s disadvantage is that it breaks easily as it changes volume immensely during charging and discharging and that solid electrolyte interfacial layers form thickly along the broken surface, deteriorating the lithium ion transfer. 
The research team overcame this problem by proposing a new design at the material level. The volume expansion problem of silicon was alleviated by using porous silicon nanowires (a nanometer scale rod); the internal pores took in the expanded silicon upon charging, helping the silicon to survive without breaking. These porous silicon nanowires were then connected to have a higher density and were covered with nanometers-thick carbon. Through the new design, the coral-shaped ‘silicon-carbon composite one-piece electrode’ improved the electric conductivity and high-speed charging.
The research results were published in ACS Nano, IF 13.709 (Feb. 26).