Improving the Electrochemical Performance of Ni‐Rich LiNi0.8Co0.1Mn0.1O2 by Enlarging the Li Layer Spacing

Ni‐rich cathode materials have high capacities but exhibit serious capacity attenuation. Therefore, a strategy for modifying a LiNi0.8Co0.1Mn0.1O2 cathode material by Na doping of the Li+ sites is proposed to improve its electrochemical performance. In this work, Li1−xNaxNi0.8Co0.1Mn0.1O2 (x=0, 0.01, 0.03) materials are synthesized by a co‐precipitation and solid‐state sintering method, and their structures and electrochemical properties are analyzed. X‐ray diffraction (XRD) results suggest that all the prepared materials have a typical hexagonal layered structure with no impurities. The spacing of the Li layers increases from 2.59251 Å to 2.59805 Å, which shows that a small amount of larger Na ions (0.102 nm) occupy the Li sites (0.076 nm). Additionally, electrochemical measurements show that the high‐rate performance and cycling stability are significantly improved when some of the Li+ sites in LiNi0.8Co0.1Mn0.1O2 are occupied by Na+. Specifically, the capacity retention of Li0.99Na0.01Ni0.8Co0.1Mn0.1O2 is 91 % after 100 cycles at a rate of 10 C. Meanwhile, the mechanism about electrochemical performance was improved by doping Na+ into Li+ sites of LiNi0.8Co0.1Mn0.1O2 has been further discussed.