Large-scale production of highly stable silicon monoxide nanowires by radio-frequency thermal plasma as anodes for high-performance Li-ion batteries

Abstract The ideal anode materials for lithium-ion batteries require high specific capacity, excellent electrochemical stability and robust mechanical properties. Silicon nanowires (Si NWs) may be a suitable anode material. However, the anisotropic expansion of Si NWs depending on crystallographic orientation frequently leads to their fractures and poor stability. Herein, amorphous silicon monoxide (SiO) NWs with Si as the head (SiO/Si NWs) are predicted and mass (120 g h−1) synthesized by using a radio-frequency (RF) plasma system. Owing to the unique one-dimensional (1D) nanostructures with homogeneous Li+ insertion and isotropic expansion, the SiO/Si NWs exhibited excellent electrochemical performance. And the SiO/Si NWs with multiple reaction sites and short diffusion length possessed significant pseudocapacitive properties. Moreover, the uniform and meager volume expansion (~40%), excellent structural stability and superior tenacity of SiO/Si NWs are directly observed by in-situ transmission electron microscope (TEM). Subsequently, the vertical graphene-like carbon encapsulation of SiO/Si NWs (SiO/Si/C NWs) is prepared by chemical vapor deposition (CVD) process. As anodes, SiO/Si/C NWs show an ultra-stable capacity of 650 m Ah g−1 for 1000 cycles even at 2.0 C, manifesting great promise for the forthcoming industrialized high-performance batteries.