Growth of Aligned Silicon Nanohelix Arrays for High-Performance Lithium Batteries by Glancing Angle Deposition System
Hsiao-Chien Wang1*, Wen-Chun Yen2, Stuart R. Thomas1, Yu-Lun Chueh1
1Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
2Giga Solar Materials Corporation, Hsinchu, Taiwan
* presenting author:Hsiao-Chien Wang,
With renewable energy production fast becoming one of the most important challenges in the 21st century, the issue of efficient energy storage is now one of the key bottlenecks that must be overcome. With a maximum theoretical specific capacity of ~3600 mAh/g, silicon is currently one of the most promising candidates for the next generation of anode materials in lithium batteries. Although Si has approximately ten times the specific capacity of graphite, its poor cycle life and material pulverization (due to expansion under Li alloying) presents an issue that must be addressed before commercial application can be realized.
In this work, we utilize a glancing angle deposition system (GLAD) to fabricate helically structured Si nanorods directly on the current collector as an anode material in lithium batteries. Using GLAD, we are able to adjust α and φ tilt angles of the substrate during the deposition process, enabling us to control the shape and position/density of our Si nanohelix structures. Doing so, we are able to mitigate the negative volume expansion issues Si anodes typically suffer, such as mechanical damage and loss of conductivity, whilst an increased surface are can enhance the potential power density. To date, we are able to demonstrate a specific capacity as high as 763.63 mAh/cm3 utilizing optimised aligned Si nanohelix structured thin-films. We believe that this work offers a promising outlook for low-cost high-performance lithium batteries for use as an energy storage solution.

Keywords: Lithium battery, Si anode, Nanohelix thin film, Glancing angle deposition