| 초록 |
Silicon can be utilized for sodium ion battery anodes in a form of silicon oxycarbide, which was simply made by pyrolyzing silicone oil under an H2/Ar atmosphere. Calcination temperature, calcination holding time, and ball-milling time were changed to gain the optimized procedure to get the best structure and composition. The mechanism of sodium ions insertion and extraction into silicon oxycarbide material is similar to the process in lithium ion batteries, except the initial step of desodiation. This material obtained almost 190 mAh g-1 first sodium ions extraction capacity at 25 mA g-1 current density and could retain the capacity of 160 mAh g-1 after 100 cycles with a good stability. It delivered 100 mAh g-1 at more than 1C (200 mA g-1) current density. At high current density, 6400 mA g-1, the material had low capacity, but gained 97% of its initial capacity after the current density was changed back into 25 mA g-1. On the small voltage range (0.0 – 0.5 V), it obtained 75% of sodium ions insertion capacity and 50% of extraction capacity. The performance of this material is better than silicon oxycarbide which was made using sol-gel method from other precursors. |
