The high cycling performance of ultra-thin Si nanowires fabricated by metal-assisted chemical etching method as lithium-ion batteries anode

The main method for the fabrication of Si nanowires (SiNWs) includes chemical vapor deposition (CVD) and metal assisted chemical etching (MCE). In the conventional MCE method, Ag catalysts are generated in a Ag+ solution. Because of the anisotropic growth of crystalline Ag, the size of the SiNWs is limited. To etch thinner SiNWs, compact and porous catalysts have been fabricated by fast-ion sputtering on Si substrates. Then, ultra-thin SiNWs (approximately 10 nm) can be etched by HF and H2O2 solution. The SiNWs fabricated by the two different methods above are assembled in a CR2025 coin cell. The 2nd discharge capacity of ultra-thin SiNWs and conventional SiNWs is 2483 and 2187 mAh/g, respectively. After 100 cycles, the discharge capacity is 1823 and 1156 mAh/g, that means the conventional SiNWs decays about 47% and ultra-thin SiNWs decays about 27%. It shows that the ultra-thin SiNWs exhibit higher cycling performance and electrochemical activity.