Effect of fluorine on the electrochemical performance of spherical LiNi0.8Co0.1Mn0.1O2 cathode materials via a low temperature method

Spherical LiNi0.8Co0.1Mn0.1O2 materials have been synthesized by hydroxide co-precipitation method. Layered oxyfluoride LiNi0.8Co0.1Mn0.1O2 − zFz (0 ≤ z ≤ 0.06) cathodes have been synthesized by firing NH4F with LiNi0.8Co0.1Mn0.1O2 oxides at the relatively low temperature of 450 °C. The effect of fluorine content on the structure, morphology and electrochemical performance of the LiNi0.8Co0.1Mn0.1O2 − zFz has been extensively studied. The results indicated that the initial discharge capacity slightly decreased with the increase in the content of fluorine substitution. However, cycling performance and rate capability were improved by the fluorine substitution. Capacity retentions after 100 cycles at room temperature were 79.7% for z = 0, 94.3% for z = 0.02, 91.5% for z = 0.04, and 86.9% for z = 0.06. In addition, after being stored at 90 °C for 5 h in a fully charged state, fluorine substituted LiNi0.8Co0.1Mn0.1O2 exhibited better cycling performance than pristine LiNi0.8Co0.1Mn0.1O2. Overall, fluorine substitution was an effective way to improve electrochemical performance.