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Issue 48, 2014
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Bicontinuous hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite with enhanced fast sodium and lithium ions intercalation chemistry

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Abstract

Mixed polyanion materials with a 3D framework for battery electrodes have been attracting significant attention recently in view of the requirements to further improve energy storage and power densities. Herein, we present a design of a hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite as sodium- and lithium-storage cathode materials. The hierarchical structure is composed of a 1D rectangular Na7V4(P2O7)4(PO4)/C nanorod, which is coated by in situ residual carbon and wrapped by a reduced graphene-oxide sheet. The open network of graphene and the surface carbon coating of the Na7V4(P2O7)4(PO4)/C nanorod provide bicontinuous electron and ion pathways, providing a three-dimensional conductive network for efficient electron and ion transfer. The flexible electrode built from the hierarchical composite free of binder or conductive additive exhibits improved electron conductivity and higher sodium/lithium ion migration coefficients than the pristine Na7V4(P2O7)4(PO4)/C nanorod. It approaches the initial reversible electrochemical capacities of 91.4 and 91.8 mA h g−1 with high discharge potentials over 3.8 V (vs. Na/Na+ or Li/Li+) and good cycling properties with capacity retentions of 95% and 83% after 200 cycles at a 1 C rate in sodium and lithium intercalation systems, respectively. Even at 10 C, it still delivers 87.4% (for sodium) and 78.2% (for lithium) of the capacity and high cycling stability. Taking into consideration the compatibilities of both sodium/lithium ions and their superior electrochemical characteristics, the bicontinuous hierarchical composite is considered to be a promising high-rate capability electrode material for advanced energy storage applications.

Graphical abstract: Bicontinuous hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite with enhanced fast sodium and lithium ions intercalation chemistry

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Publication details

The article was received on 30 Aug 2014, accepted on 22 Oct 2014 and first published on 22 Oct 2014


Article type: Paper
DOI: 10.1039/C4TA04499A
Author version available: Download Author version (PDF)
Citation: J. Mater. Chem. A, 2014,2, 20538-20544
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    Bicontinuous hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite with enhanced fast sodium and lithium ions intercalation chemistry

    S. Zhang, C. Deng and Y. Meng, J. Mater. Chem. A, 2014, 2, 20538
    DOI: 10.1039/C4TA04499A

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