A low temperature fluorine substitution on the electrochemical performance of layered LiNi0.8Co0.1Mn0.1O2−zFz cathode materials

Fluorine substituted LiNi0.8Co0.1Mn0.1O2 cathode materials have been synthesized by calcining NH4F with spherical LiNi0.8Co0.1Mn0.1O2 oxides at a relatively low temperature of 450 °C. The structure, morphology and electrochemical performance of spherical LiNi0.8Co0.1Mn0.1O2−zFz materials have been investigated. The XRD, composition analysis and XPS verify fluorine incorporation in the particle. Although the fluorine substituted material shows somewhat lower initial discharge capacity, it exhibits improved cycling performance compared with the pristine material. XRD pattern shows that the fluorine substituted material maintains stable layered structure after 100 cycles. TEM analysis provides evidences that the fluorine substituted powder still presents smooth surface without any structure transformation. From these results, it is believed that the improved cycling performance of fluorine substituted LiNi0.8Co0.1Mn0.1O2 material is attributed to fluorine substitution in protecting the electrode from HF attack and maintaining the structure stability of electrode. Besides, the fluorine substitution also plays positive effect on the cycling performance at elevated temperature and storage performance.