A low-strain V3Nb17O50 anode compound for superior Li+ storage

Abstract M–Nb–O compounds are regarded as advanced anode materials of lithium-ion batteries owing to their large capacities, high safety and fast Li+ transport. However, challenges remain in the exploitation of new M–Nb–O compounds with low strains to enable superior cyclability. Here, we exploit V3Nb17O50 as a low-strain M–Nb–O anode compound, and V3Nb17O50 micron-sized particles (V3Nb17O50-MP) and submicron-sized rods (V3Nb17O50-SR) are demonstrated. V3Nb17O50 owns an open and robust shear ReO3 crystal structure, which is constructed by 3 × 3 × ∞ (V,Nb)O6 octahedron-blocks linked by VO4 tetrahedra. The resulting A–B–A layered structure with a large interlayer spacing enables the superior Li+ diffusivity and significant intercalation-pseudocapacitive behavior in V3Nb17O50. The maximum unit-cell volume expansion of V3Nb17O50 discharged to 0.8 V is only 3.46% (the smallest value among the known M–Nb–O anode compounds with shear ReO3 structures), leading to the excellent cyclability of V3Nb17O50-MP/V3Nb17O50-SR with 90.0/91.8% capacity retention over 2000 cycles at 10C. V3Nb17O50-MP/V3Nb17O50-SR further exhibits a safe operating potential of 1.736/1.724 V, large reversible capacity of 207/254 mA h g−1 at 0.1C, and high rate performance with 68/123 mA h g−1 at 10C. A LiMn2O4//V3Nb17O50-SR full cell also exhibits comprehensively good electrochemical properties, including excellent cyclability with 85.7% capacity retention over 500 cycles at 5C. Therefore, V3Nb17O50 can be a very promising anode compound for stable, safe, large-capacity and fast-charging Li+ storage.