LiNbO₃ Coating and F^- Doping Stabilize the Crystal Structure and Ameliorate the Interface of LiNi_0.88Co_0.06Mn_0.03Al_0.03O< sub>2 to Improve the Electrochemical Properties and Safety Capability

Ni-rich layered materials Li[NixCoyMnzAl1-x-y-z]O-2 (x > 0.8) are regarded as the competitive cathode for practical applications in lithium-ion batteries owing to the large discharging capacity. Nevertheless, the strong oxidation activity, the poor structure, and the thermal stability at the electrode-electrolyte interface would lead to much trouble, for example, inferior electrochemical properties and acute safety issues. To ameliorate the above problems, this work reports a strategy for the double modification of F- doping and LiNbO3 covering in LiNi0.88Co0.06Mn0.03Al0.03O2 cathode via using high-temperature calcining and ball-milling technology. As a result, the cathodes after F- doping and LiNbO3 covering not only demonstrate a more stabilized crystal structure and particle interface but also reduce the release of high-activity oxygen species to ameliorate the thermal runaway. The electrochemical tests show that the LiNbO3-F--modified cathode displays a superior rate capability of 159.3 mAh g(-1) at 10.0 C and has the predominant capability retention of 92.1% in the 200th cycle at 25 degrees C, much superior than those (125.4 mAh g(-1) and 84.0%) of bare cathode. Thus, the F- doped and LiNbO3-coated Ni-rich oxides could be a promising cathode to realize the high capacity and a stabilized interface.