Improved Electrochemical Performance of Silicon Nanowires As Negative Electrode with Metal Coatings

In this study, we report the effect of metal coated silicon nanowires (SiNWs) on electrochemical performance as a negative electrode material. We fabricated metal coated SiNWs by using metal assisted chemical etching process. Transmission electron microscopy (TEM) images show that SiNW arrays with silver (Ag) coating on a Si (100) substrate have been successfully prepared in a one-pot process. To investigate the electrochemical performances of Ag-coated SiNWs, coin cells using SiNWs as negative electrodes by the slurry coating method were assembled with Li metal foil as the counter electrode. We show that the rate capability of Ag coated SiNWs is greatly improved compare to bare NWs. Also, the good cycling performances of the Ag-coated SiNWs were clearly observed. The enhanced electrochemical performance is attributed to the improvement of electrical conductivity of SiNWs. Furthermore, we suggest that the Ag layer is exposed to the electrolyte instead of bare Si, and it can prevent solid electrolyte interface (SEI) formation and deterioration of active materials.