Cr0.5Nb24.5O62 Nanowires with High Electronic Conductivity for High-Rate and Long-Life Lithium-Ion Storage

Intercalation-type TiNb x O 2+2.5 x ( x = 2, 5, and 24) anode materials have recently become more interesting for lithium-ion batteries (LIBs) due to their large theoretical capacities of 388–402 mAh g –1 . However, the Ti 4+ /Nb 5+ ions in TiNb x O 2+2.5 x with empty 3d/4d orbitals usually lead to extremely low electronic conductivity of <10 –9 S cm –1, greatly restricting their practical capacity and rate capability. Herein, we report a class of highly conductive Cr 0.5 Nb 24.5 O 62 nanowires as an intercalation-type anode material for high-performance LIBs. The as-made Cr 0.5 Nb 24.5 O 62 nanowires show an open shear ReO 3 crystal structure ( C 2 space group) with 4% tetrahedra and a conducting characteristic with ultrahigh electronic conductivity of 3.6 × 10 –2 S cm –1 and a large Li + -ion diffusion coefficient of 2.19 × 10 –13 cm 2 s –1 . These important characteristics make them deliver outstanding electrochemical properties in term of the largest reversible capacity (344 mAh g –1 at 0.1 C) in all the known niobium- and titanium-based anode materials, safe working potential (∼1.65 V vs Li/Li + ), high first-cycle Coulombic efficiency (90.8%), superior rate capability (209 mAh g –1 at 30 C), and excellent cycling stability, making them among the best for LIBs in niobium- and titanium-based anode materials.