Scalable Synthesis of Defect Abundant Si Nanorods for High-Performance Li-Ion Battery Anodes

详细信息    查看全文

• 作者：Jing Wang ; Xiangcai Meng ; Xiulin Fan ; Wenbo Zhang ; Hongyong Zhang ; Chunsheng Wang
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：9
• 期：6
• 页码：6576-6586
• 全文大小：716K
• ISSN：1936-086X

文摘

Microsized nanostructured silicon鈥揷arbon composite is a promising anode material for high energy Li-ion batteries. However, large-scale synthesis of high-performance nano-Si materials at a low cost still remains a significant challenge. We report a scalable low cost method to synthesize Al/Na-doped and defect-abundant Si nanorods that have excellent electrochemical performance with high first-cycle Coulombic efficiency (90%). The unique Si nanorods are synthesized by acid etching the refined and rapidly solidified eutectic Al鈥揝i ingot. To maintain the high electronic conductivity, a thin layer of carbon is then coated on the Si nanorods by carbonization of self-polymerized polydopamine (PDA) at 800 掳C. The carbon coated Si nanorods (Si@C) electrode at 0.9 mg cm^鈥? loading (corresponding to area-specific-capacity of 鈭?.0 mAh cm^鈥?) exhibits a reversible capacity of 鈭?200 mAh g^鈥? at 100 mA g^鈥? current, and maintains 鈭?00 mAh g^鈥? over 1000 cycles at 1000 mA g^鈥? with a capacity decay rate of 0.02% per cycle. High Coulombic efficiencies of 87% in the first cycle and 鈭?9.7% after 5 cycles are achieved due to the formation of an artificial Al₂O₃ solid electrolyte interphase (SEI) on the Si surface, and the low surface area (31 m² g^鈥?), which has never been reported before for nano-Si anodes. The excellent electrochemical performance results from the massive defects (twins, stacking faults, dislocations) and Al/Na doping in Si nanorods induced by rapid solidification and Na salt modifications; this greatly enhances the robustness of Si from the volume changes and alleviates the mechanical stress/strain of the Si nanorods during the lithium insertion/extraction process. Introducing massive defects and Al/Na doping in eutectic Si nanorods for Li-ion battery anodes is unexplored territory. We venture this uncharted territory to commercialize this nanostructured Si anode for the next generation of Li-ion batteries.