Sodium-ion batteries (SIBs) are evolving as low cost alternative to the state-of-the-art lithium-ion batteries (LIBs). Elementary properties of sodium, high abundance and low cost associated with sodium precursors made it a realistic alternative to lithium-ion chemistry [1,2]. Apparently the energy density of sodium-ion batteries is low compared to state-of-the-art LIBs. However, cost-effective, sustainable and safe battery systems could be achieved with SIBs (top most priorities for grid application). Research activities on SIBs are growing worldwide and still require a great deal of basic research. Synthesis and testing of new electrode materials is of great interest to realize the structural requirements to build sustainable and safe sodium-ion batteries.
Here, we present synthesis and electrochemical properties of new sodium vanadium oxy phosphate (NaVOP), Na3V3P2O13. The compound was synthesized by a two-step solid-state reaction. The structure of Na3V3P2O13 was identified by Rietveld refinement of the powder X-ray diffraction (XRD) pattern. The structure of parent compound Na2V3P2O13 (Figure) was used as the starting model. The half cells with Na2V3P2O13 as cathode and Na metal as anode shows a reversible capacity of 105 mAh/g at an average voltage of 2.7 V vs. Na+/Na when cycled in the voltage range of 4.5-2.0 V. High reversible capacity of 150 mAh/g could be obtained when cycled in the voltage rage of 4.5-1.5 V. Post structural analysis shows the compound is structurally stable over a broad range of sodium extraction and reinsertion demonstrating its potential as cathode material for sodium-ion batteries.
1. M. D. Slater, D. Kim, E. Lee C. S. Johnson, Adv. Funct. Mater. 2013, 23, 947–958.
2. N. Yabuuchi, K. Kubota, M. Dahbi, S. Komaba, Chem. Rev. 2014, 114 (23), 11636–11682.
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