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

The FeF 3 -coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]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 X-ray diffraction, scanning electron microscopy, and transmission electron microscopy . The results indicated that the surface of cathode particles was covered by FeF 3 film (about 5–15   nm thick). Compared with the bare cathode, the FeF 3 -coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]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 FeF 3 -coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]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 FeF 3 coating layer , which suppressed the side reaction between the Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 particles with electrolyte and further stabilized the Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 structure with cycling.