A Study on the Material and Structural Viewpoints for Enhancement of Silicon Anodes Performance for Lithium-ion Batteries

Abstract

In this study, Si materials related study and structuralization of Si electrode was conducted. First, a Si/SiOx/Co composite was synthesized using a facile solid-state reaction. Since the Co metal in the Si/SiOx/Co composite has high ductility and electrical conductivity, it can act as an effective buffer as well as act as an effective conductive agent. In addition, the Si/SiOx/Co electrode can maintain its conductive network during cycling. As the results, the charge transfer resistance of the cycled Si/SiOx/Co anode was 8 times lower than that of the Si anode. Furthermore, the Si/SiOx/Co anode exhibits a high specific capacity of 1,602 mAh g-1Si/SiOx after 200 cycles at a current of 2 A g-1, while the Si anode exhibits a specific capacity of 351 mAh g-1Si. These improvements in electrochemical performance are ascribed to the ductile Co metal in the Si/SiOx/Co composite. Structuralization of the Si electrodes was also conducted. We confirmed formation of a dense surface layer on the Si electrodes and it was removed by nanosecond laser. The cycle ability of the laser treated Si electrodes was improved by reducing the mechanical stress in the dense surface layer on the electrodes. As a result, the laser structured Si anode exhibits a high specific capacity of 405 mAh g-1Si after 400 cycles at a current rate of 2 A g-1 while bare Si anode exhibits a low specific capacity of 75 mAh g-1Si. In addition, the mass loss of the laser treated electrodes was under 10 wt.% since only surface region was processed by laser. Its facile processing, low mass loss and high electrochemical performance enhancements make it suitable for large-scale applications in LIBs.