Fluorine-Doped LiNi 0.8 Mn 0.1 Co 0.1 O 2 Cathode for High-Performance Lithium-Ion Batteries
Hyeona Kim, Sung-Beom Kim, Deok‐Hye Park, Kyung‐Won Park
Abstract
For advanced lithium-ion batteries, LiNi x Co y Mn z O 2 (x + y + z = 1) (NCM) cathode materials containing a high nickel content have been attractive because of their high capacity. However, to solve severe problems such as cation mixing, oxygen evolution, and transition metal dissolution in LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathodes, in this study, F-doped LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCMF) was synthesized by solid-state reaction of a NCM and ammonium fluoride, followed by heating process. From X-ray diffraction analysis and X-ray photoelectron spectroscopy, the oxygen in NCM can be replaced by F − ions to produce the F-doped NCM structure. The substitution of oxygen with F − ions may produce relatively strong bonds between the transition metal and F and increase the c lattice parameter of the structure. The NCMF cathode exhibits better electrochemical performance and stability in half- and full-cell tests compared to the NCM cathode.