title: 1D nanostructured Na7V4(P2O7)4(PO4) as high-potential and superior-performance cathode material for sodium-ion batteries.
abstract: Tailoring materials into nanostructure offers unprecedented opportunities in the utilization of their functional properties. High-purity Na7V4(P2O7)4(PO4) with 1D nanostructure is prepared as a cathode material for rechargeable Na-ion batteries. An efficient synthetic approach is developed by carefully controlling the crystal growth in the molten sodium phosphate. Based on the XRD, XPS, TG, and morphological characterization, a molten-salt assisted mechanism for nanoarchitecture formation is revealed. The prepared Na7V4(P2O7)4(PO4) nanorod has rectangle sides and preferential [001] growth orientation. GITT evaluation indicates that the sodium de/intercalation of Na7V4(P2O7)4(PO4) nanorod involves V(3+)/V(4+) redox reaction and Na5V(3.5+)4(P2O7)4(PO4) as intermediate phase, which results in two pairs of potential plateaus at the equilibrium potentials of 3.8713 V (V(3+)/V(3.5+)) and 3.8879 V (V(3.5+)/V(4+)), respectively. The unique nanoarchitecture of the phase-pure Na7V4(P2O7)4(PO4) facilitates its reversible sodium de/intercalation, which is beneficial to the high-rate capability and the cycling stability. The Na7V4(P2O7)4(PO4) cathode delivers 80% of the capacity (obtained at C/20) at the 10 C rate and 95% of the initial capacity after 200 cycles. Therefore, it is feasible to design and fabricate an advanced rechargeable sodium-ion battery by employment of 1D nanostructured Na7V4(P2O7)4(PO4) as the cathode material.
authors.affiliation: Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education; College of Chemistry and Chemical Engineering, Harbin Normal University , Harbin, 150025, Heilongjiang China.
authors.forename: Chao
authors.initials: C
authors.lastname: Deng
authors.forename: Sen
authors.initials: S
authors.lastname: Zhang
mesh_terms: D011211:Electric Power Supplies; D004566:Electrodes; D049329:Nanostructures / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D017968:Vanadium Compounds / Q000737:chemistry
chemical_list: D010710:Phosphates; D017968:Vanadium Compounds; D012964:Sodium; C018279:sodium phosphate