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

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 V 3 Nb 17 O 50 as a low-strain M–Nb–O anode compound, and V 3 Nb 17 O 50 micron-sized particles (V 3 Nb 17 O 50 -MP) and submicron-sized rods (V 3 Nb 17 O 50 -SR) are demonstrated. V 3 Nb 17 O 50 owns an open and robust shear ReO 3 crystal structure, which is constructed by 3 ​× ​3 ​× ​∞ (V,Nb)O 6 octahedron-blocks linked by VO 4 tetrahedra. The resulting A–B–A layered structure with a large interlayer spacing enables the superior Li + diffusivity and significant intercalation-pseudocapacitive behavior in V 3 Nb 17 O 50 . The maximum unit-cell volume expansion of V 3 Nb 17 O 50 discharged to 0.8 ​V is only 3.46% (the smallest value among the known M–Nb–O anode compounds with shear ReO 3 structures), leading to the excellent cyclability of V 3 Nb 17 O 50 -MP/V 3 Nb 17 O 50 -SR with 90.0/91.8% capacity retention over 2000 cycles at 10C. V 3 Nb 17 O 50 -MP/V 3 Nb 17 O 50 -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 LiMn 2 O 4 //V 3 Nb 17 O 50 -SR full cell also exhibits comprehensively good electrochemical properties , including excellent cyclability with 85.7% capacity retention over 500 cycles at 5C. Therefore, V 3 Nb 17 O 50 can be a very promising anode compound for stable, safe, large-capacity and fast-charging Li + storage.