Enhanced electrochemical performance of LiF-modified LiNi1/3Co1/3Mn1/3O2 cathode materials for Li-ion batteries

LiF is successful used to modify the surface of layered LiNi1/3Co1/3Mn1/3O2 via a wet chemical method followed by an annealing process. The lattice structure of LiNi1/3Co1/3Mn1/3O2 is not changed distinctly after modification and part of F- dopes into the surface lattice of the oxide. The LiF-modified oxide exhibits capacity retentions of 97.5% at 0.1 C at room temperature and 93.5% at 1 C at 60 degrees C after 50 cycles, and delivers a high discharge capacity of 137 mAh g(-1) at 10 C at room temperature. Furthermore, it has reversible capacities of 124.4 mAh g(-1) at 1 C at 0 degrees C and 85.6 mAh g(-1) at 0.1 C at -20 degrees C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests show that the LiF-modified layer can reduce the dissolution of metal ions in the electrode and enhance the conductivity of the oxide surface through partly F-substitution. LiF modification will be promising for the application of layered oxide for lithium ion batteries. (C) 2012 Elsevier B.V. All rights reserved.