Influences of FeF3 coating layer on the electrochemical properties of Li [Li0.2Mn0.54Ni0.13Co0.13]O2 cathode materials for lithium-ion batteries

The FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 cathode materials were synthesized via a wet chemical process followed by a solid state reaction. The physical properties of the as-prepared samples were conducted using Xray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicated that the surface of cathode particles was covered by FeF3 film (about 5-15 nm thick). Compared with the bare cathode, the FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 one delivered the higher coulombic efficiency, better rate capability, longer cycle life, and better structure stability. A high capacity retention of 95% (190 mAh g(-1)) after 100 cycles at 0.5 C rate was obtained for the FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 cathode. Besides, the results from cyclic voltammetry and electrochemical impedance spectra revealed that the noteworthy enhanced electrochemical properties of the surface-modified sample were due to the presence of FeF3 coating layer, which suppressed the side reaction between the Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 particles with electrolyte and further stabilized the Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 structure with cycling. (C) 2016 Elsevier B.V. All rights reserved.