Mg²⁺-doped Na₃V₂(PO₄)₃/C decorated with graphene sheets: An ultrafast Na-storage cathode for advanced energy storage

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• 作者：Guiying Xu^a ; ^b ; Guogang Sun^b ; ^{guogangsun_cup@sina.com" class="auth_mail" title="E-mail the corresponding author} ; ^{ggsunbj@126.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Sodium-ion batteries ; Na3V2(PO4)3/C ; Graphene sheets ; Mg2+ doping ; High-rate performance ; Cathode material
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：42
• 期：13
• 页码：14774-14781
• 全文大小：3157 K

文摘

NASICON-type Na₃V₂(PO₄)₃ is one of the most promising cathode materials for sodium-ion batteries, delivering about two Na⁺-ions extraction/insertion from/into the unit structure. However, the low electronic conductivity which leads to bad rate capability and poor cycle performance, limits its practical application for sodium-ion batteries. To overcome the kinetic problem, we attempt to prepare the carbon-coated Na₃V₂(PO₄)₃ nanocrystals further decorated by graphene sheets and doped with Mg²⁺ ion via the two steps of sol-gel process and solid-state treatment for the first time. Such architecture synergistically combines the advantages of two-dimensional graphene sheets and 0-dimensional Mg²⁺-doped Na₃V₂(PO₄)₃/C nanoparticles. It greatly increases the electron/Na⁺-ion transport kinetics and assures the electrode structure integrity, leading to attractive electrochemical performance. When used as sodium-ion batteries cathode, the hybrid composite delivers an initial discharge capacity of 115.2 mAh g⁻¹ at 0.2 C rate, and retains stable discharge capacities of 113.1, 109.0, 102.4, 94.0 and 85.2 mAh g⁻¹ at high current rates of 1, 2, 5, 10 and 20 C rate, respectively. Thus, this nanostructure design provides a promising pathway for developing high-performance Na₃V₂(PO₄)₃ material for sodium-ion batteries.