Superior performance of silicon nanowires@void@carbon on a conductive substrate as a scalable binder-free anode electrode for lithium-ion batteries

Abstract

There has been great interest in silicon-based anode materials for use in lithium-ion batteries (LIBs), and they have been implemented in multiple commercialized batteries in recent years. Herein, we present the synthesis of high-performance binder-free anode electrodes from carbon-coated silicon nanowires in a yolk–shell structure, with superior specific capacity, cycle life, rate capability, and coulombic efficiency. The silicon nanowires were grown on a stainless steel current collector via a low pressure chemical vapor deposition (LPCVD) process. A consequent silica sacrificial layer was conformally coated on the nanowires, followed by the direct current-plasma enhanced chemical vapor deposition (DC-PECVD) of a carbon nanolayer. The removal of the silica layer resulted in the formation of yolk–shell nanowires, which were implemented in a half-cell configuration LIB coin cell to investigate the electrochemical performance. At a current rate of 0.2C, an initial discharge specific capacity of 2882 mA h g⁻¹ was achieved in the first cycle, which reached 1681 mA h g⁻¹ at the end of 543 cycles. This is the first reported LIB anode electrode composed of silicon@void@carbon nanowires grown on a conductive substrate, and it offers excellent specific capacity, which in its lowest state is approximately 4.5 times that of the theoretical specific capacity of traditional graphite electrodes. This binder-free silicon-based electrode was realized through a controllable and scalable process, and can be implemented in high-performance LIBs.