Highly conductive CrNb11O29 nanorods for use in high-energy, safe, fast-charging and stable lithium-ion batteries.

Ti 2 Nb 2 x O 4+5 x compounds are very popular negative-electrode materials for lithium-ion batteries due to their high specific capacities, safe operating potentials and high cycling stability. Nevertheless, their poor electronic conductivities and insufficient Li + diffusion coefficients limit the rate capabilities. Herein, we explore highly conductive CrNb 11 O 29 with a high theoretical capacity (401 mAh g −1 ) and an open Wadsley–Roth shear structure as a new intercalating negative-electrode material having the same advantages of Ti 2 Nb 2 x O 4+5 x but a high rate capability. CrNb 11 O 29 nanorods (CrNb 11 O 29 -R) with lengths of 500–1000 nm and very small diameters of 30–50 nm are prepared based on a novel hydrothermal method. Due to the free electrons in Cr-3d orbitals and the large ionic radius of Cr 3+ , CrNb 11 O 29 exhibits a high electronic conductivity and large Li + diffusion coefficients, respectively. In-situ X-ray diffraction analyses confirm its high structural stability. These conductivity, structural and architectural advantages in CrNb 11 O 29 -R lead to its significant pseudocapacitive contribution (82.0% at 1.1 mV s −1 ), prominent rate capability (high reversible capacities of 343 mAh g −1 at 0.1C and 228 mAh g −1 at 10C), and outstanding cycling stability (only 8.9% capacity loss at 10C over 400 cycles). [ABSTRACT FROM AUTHOR]