Improvement of Na Ion Electrode Activity of Metal Oxide via Composite Formation with Metal Sulfide

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• 作者：Seung Mi Oh ; In Young Kim ; Sharad B. Patil ; Boyeon Park ; Jang Mee Lee ; Kanyaporn Adpakpang ; Seen Ae Chae ; Oc Hee Han ; Seong-Ju Hwang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 25, 2017
• 年：2017
• 卷：9
• 期：3
• 页码：2249-2260
• 全文大小：777K
• ISSN：1944-8252

文摘

The composite formation with a conductive metal sulfide domain can provide an effective methodology to improve the Na-ion electrode functionality of metal oxide. The heat treatment of TiOb>2b>(B) under CSb>2b> flow yields an intimately coupled TiOb>2b>(B)–TiSb>2b> nanocomposite with intervened TiSb>2b> domain, since the reaction between metal oxide and CSb>2b> leads to the formation of metal sulfide and COb>2b>. The negligible change in lattice parameters and significant enhancement of visible light absorption upon the reaction with CSb>2b> underscore the formation of conductive metal sulfide domains. The resulting TiOb>2b>(B)–TiSb>2b> nanocomposites deliver greater discharge capacities with better rate characteristics for electrochemical sodiation–desodiation process than does the pristine TiOb>2b>(B). The ²³Na magic angle spinning nuclear magnetic resonance analysis clearly demonstrates that the electrode activities of the present nanocomposites rely on the capacitive storage of Na⁺ ions, and the TiSb>2b> domains in TiOb>2b>(B)–TiSb>2b> nanocomposites play a role as mediators for Na⁺ ions to and from TiOb>2b>(B) domains. According to the electrochemical impedance spectroscopy, the reaction with CSb>2b> leads to the significant enhancement of charge transfer kinetics, which is responsible for the accompanying improvement in electrode performance. The present study provides clear evidence for the usefulness in composite formation between the semiconducting metal oxide and metal sulfide in exploring new efficient NIB electrode materials.