Micron-Sized a-Silicon-Fe-Cu Ternary Composite Anode Material for High Energy Libs

Wednesday, October 14, 2015: 08:40
Russell B (Hyatt Regency)
S. Chae (UNIST) and J. Cho (UNIST)
To realize the high energy LIBs, extensive studies for silicon anodes have been widely carried out for recent years in order to succeed in commercialization through overcoming its intrinsic problems of low coulombic efficiency and severe capacity degradation upon cycling as results of large volume expansion, low conductivity and lithium diffusivity. Herein, we suggested a sophisticated structure of silicon-based ternary alloy composite with a scalable series of processes by synthesizing high density micron-sized secondary particles comprising of metal silicide and amorphous silicon primary particles (~100 nm). This silicon-based ternary alloy composite, whose reversible specific capacity is 1300 mAh/g with 85% coulombic efficiency at 1st cycle, shows not only great cycling stability with 84% retention at 0.5 C after 100th cycles but also high rate capability with 91% of capacities retention at 7C (vs. 0.2C). These remarkable electrochemical properties come from a-silicon characteristics and formation of either Fe-Si or Cu-Si alloys with reactions of a-Si, leading to improve the structural integrity with porosity. This silicon-based ternary alloy composite have also succeeded in increasing the tap density as high as 0.8 g/cm3. Furthermore, the electrode was swollen only 42% after 100th cycles. In these regards, the silicon-based ternary alloy composite will contribute to the progress of practical use of silicon anode for next generation LIBs.