Synthesis and Charge Storage Properties of Hierarchical Niobium Pentoxide/Carbon/Niobium Carbide (MXene) Hybrid Materials

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• 作者：Chuanfang Zhang ; Majid Beidaghi ; Michael Naguib ; Maria R. Lukatskaya ; Meng-Qiang Zhao ; Boris Dyatkin ; Kevin M. Cook ; Seon Joon Kim ; Brandon Eng ; Xu Xiao ; Donghui Long ; Wenming Qiao ; Bruce Dunn ; Yury Gogotsi
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：June 14, 2016
• 年：2016
• 卷：28
• 期：11
• 页码：3937-3943
• 全文大小：459K
• 年卷期：0
• ISSN：1520-5002

文摘

Orthorhombic niobium pentoxide (T-Nb₂O₅) offers high capacitance and fast charging–discharging rate capabilities when used as an electrode material for Li-ion capacitors. A homogeneous distribution of T-Nb₂O₅ nanoparticles in a highly conductive matrix represents a promising approach to maximize its energy and power densities. Here we report a one-step CO₂ oxidation of two-dimensional (2D) Nb₂CT_x, a member of the MXenes family of 2D transition metal carbides, which leads to a hierarchical hybrid material with T-Nb₂O₅ nanoparticles uniformly supported on the surface of Nb₂CT_x sheets with disordered carbon. The oxidation temperature, duration, and CO₂ flow rate determine the T-Nb₂O₅ crystallite size as well as the structure, composition, and the charge storage properties of the hybrid material. Fifty micrometer thick electrodes of the hybrid material exhibit high capacitance (330 C g^–1 and 660 mF cm^–2 at a charge–discharge time of 4 min) and good cycling performance in a nonaqueous lithium electrolyte. The charge storage kinetics are dominated by a surface-controlled process. The observed electrochemical performance is attributed to the intrinsic pseudocapacitive response and excellent energy storage capability of T-Nb₂O₅ coupled with the fast charge transfer pathways provided by the conductive 2D Nb₂CT_x sheets and the as-formed disordered carbon.