Nb5+ doped LiV3O8 nanorods with extraordinary rate performance and cycling stability as cathodes for lithium-ion batteries

Abstract

Cathode materials are the key component and bottleneck that hinders the development of lithium-ion batteries. This work reports the preparation of LiV3O8 nanorods with different levels of Nb doping through a sol-gel process and a subsequent electrospinning method. The electrochemical performance of LiV3O8 as a cathode material was enhanced significantly upon Nb doping. A capacity of 401 mAh g−1 at 0.1C (0.52 mAh cm−2) was observed for LiV2.94Nb0.06O8, which still retained a value of 91 mAh g−1 (0.12 mAh cm−2) at 20 C. The doped cathode also showed excellent cycling stability, retaining 99.7% of its initial capacity after 500 cycles of charge and discharge. The mechanisms for the performance enhancement were investigated using experimental techniques and theoretical analysis based on density functional theory (DFT). It was found the Nb doping could expand the lattice space, reduce the bandgap, increase the intrinsic conductivity, lower the energy barrier of the reaction and promote the absorption and release kinetics of Li-ions. Furthermore, the nanorod morphology which was obtained by electrospinning, could shorten the pathway of Li-ions and provide mechanical stability and is also responsible for the excellent performance.