Improved battery performance of Fe-doped LiVPO4F with high capacity and stable cycling

LiVPO4F is considered as an upgrade of current LiFePO4 cathode for rechargeable lithium batteries due to its superior thermal stability and mildly high voltage plateau. However, the low intrinsic electric conductivity and sluggish electrochemical kinetics constrain its battery performance and practical development. Partial substitution of vanadium with iron is designed in this paper given the similarity of LiVPO4F and LiFePO4OH. The phase structure, particle size, battery performance and electrochemical kinetics of LiV1-xFexPO4F (0 <= x < 1) are comparatively studied. LiV0.9Fe0.1PO4F is found having the optimal electrochemical performance, and delivers a reversible specific capacity of 132 mA h g(-1) and 80 mA h g(-1) at C/8 and 6C, respectively. After 300 cycles at 0.5C rate, the capacity slowly reduces from 119 mA h g(-1) to 108 mA h g(-1) with a retention of 90.8%. (C) 2020 Elsevier B.V. All rights reserved.