Heterogeneous WSx/WO3 Thorn-Bush Nanofiber Electrodes for Sodium-Ion Batteries

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• 作者：Won-Hee Ryu ; Hope Wilson ; Sungwoo Sohn ; Jinyang Li ; Xiao Tong ; Evyatar Shaulsky ; Jan Schroers ; Menachem Elimelech ; André D. Taylor
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：March 22, 2016
• 年：2016
• 卷：10
• 期：3
• 页码：3257-3266
• 全文大小：683K
• ISSN：1936-086X

文摘

Heterogeneous electrode materials with hierarchical architectures promise to enable considerable improvement in future energy storage devices. In this study, we report on a tailored synthetic strategy used to create heterogeneous tungsten sulfide/oxide core–shell nanofiber materials with vertically and randomly aligned thorn-bush features, and we evaluate them as potential anode materials for high-performance Na-ion batteries. The WS_x (2 ≤ x ≤ 3, amorphous WS₃ and crystalline WS₂) nanofiber is successfully prepared by electrospinning and subsequent calcination in a reducing atmosphere. To prevent capacity degradation of the WS_x anodes originating from sulfur dissolution, a facile post-thermal treatment in air is applied to form an oxide passivation surface. Interestingly, WO₃ thorn bundles are randomly grown on the nanofiber stem, resulting from the surface conversion. We elucidate the evolving morphological and structural features of the nanofibers during post-thermal treatment. The heterogeneous thorn-bush nanofiber electrodes deliver a high second discharge capacity of 791 mAh g^–1 and improved cycle performance for 100 cycles compared to the pristine WS_x nanofiber. We show that this hierarchical design is effective in reducing sulfur dissolution, as shown by cycling analysis with counter Na electrodes.