Fluorine Doping Induced Crystal Space Change and Performance Improvement of Single Crystalline LiNi0.6Co0.2Mn0.2O2 Layered Cathode Materials

Abstract The Li−Ni−Co−Mn−O layered cathode materials are promising for the advanced lithium‐ion batteries due to their moderate cost and high specific capacity. However, the low electronic conductivity and poor stability at high currents need to be overcome to meet the ever‐growing demands. In this work, single crystal hexagonal nanosheets of LiNi 0.6 Co 0.2 Mn 0.2 O 2 are synthesized by the hydrothermal process, which are further controllably doped with fluorine to improve the lithium storage performance. The fluorine doping can not only improve the layered structure, but also increase the lattice oxygen content, to promote the lithium‐ion migration and crystal structure stability of the layered LiNi 0.6 Co 0.2 Mn 0.2 O 2 . Optimized fluorine doping leads to excellent capacity and cyclic stability of the single crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 nanosheets with an original capacity of 168.3 mAh g −1 , and an excellent capacity retention rate of 94.5 % at 1.0 C over 100 cycles, which are superior to the control samples and hold potential for the lithium‐ion battery applications.