Investigation of the Na Intercalation Mechanism into Nanosized V2O5/C Composite Cathode Material for Na-Ion Batteries

详细信息    查看全文

• 作者：Ghulam Ali ; Ji−Hoon Lee ; Si Hyoung Oh ; Byung Won Cho ; Kyung-Wan Nam ; Kyung Yoon Chung
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 9, 2016
• 年：2016
• 卷：8
• 期：9
• 页码：6032-6039
• 全文大小：453K
• ISSN：1944-8252

文摘

There is a significant interest to develop high-performance and cost-effective electrode materials for next-generation sodium ion batteries. Herein, we report a facile synthesis method for nanosized V₂O₅/C composite cathodes and their electrochemical performance as well as energy storage mechanism. The composite exhibits a discharge capacity of 255 mAh g^–1 at a current density of 0.05 C, which surpasses that of previously reported layered oxide materials. Furthermore, the electrode shows good rate capability; discharge capacity of 160 mAh g^–1 at a current density of 1 C. The reaction mechanism of V₂O₅ upon sodium insertion/extraction is investigated using ex situ X-ray diffraction (XRD) and synchrotron based near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Ex situ XRD result of the fully discharged state reveals the appearance of NaV₂O₅ as a major phase with minor Na₂V₂O₅ phase. Upon insertion of sodium into the array of parallel ladders of V₂O₅, it was confirmed that lattice parameter of c is increased by 9.09%, corresponding to the increase in the unit-cell volume of 9.2%. NEXAFS results suggest that the charge compensation during de/sodiation process accompanied by the reversible changes in the oxidation state of vanadium (V⁴⁺ ↔ V⁵⁺).