Facile synthesis of fluorine doped single crystal Ni-rich cathode material for lithium-ion batteries

• Published in: Solid state ionics Vol. 342; p. 115065
• Main Authors: Zhao, Zhiyuan, Huang, Bing, Wang, Meng, Yang, Xiaowei, Gu, Yijie
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2019; Elsevier BV
• Subjects: Batteries; Cathode material; Cathodes; Diffraction; Diffusion rate; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrode materials; Electrode polarization; Fluorine; Fluorine substitution; LiNi0.8Mn0.1Co0.1O2; Lithium; Lithium ions diffusion; Lithium-ion batteries; Photoelectrons; Rechargeable batteries; Single crystal morphology; Single crystals; Substitutes; Unit cell; X ray photoelectron spectroscopy; X-ray spectroscopy; Single crystal morphology; Lithium-ion batteries; Cathode material; LiNi0.8Mn0.1Co0.1O2; Lithium ions diffusion; Fluorine substitution
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2019.115065

Fluorine doped single crystal Ni-rich cathode material with excellent electrochemical properties were successfully synthesized. X-ray diffraction (XRD) revealed that the fluorine substitution process did not change the hexagonal layer structure, but it promoted the unit cell expanded along the c-direction which was conductive to improving the kinetic of Li+ transmission. Energy dispersive X-ray Spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) further proved the fluorine doped into the cathode material, which simultaneously triggered partial Ni3+ reduction to Ni2+. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that fluorine substitution can effectively decrease polarization and suppress migration resistance of lithium ions. The lithium ions diffusion rate (DLi+) indicated that lithium ions migrated more smoothly in fluoride doped sample. Both the substitution effects of fluorine and short migration path way for lithium ions in single crystal particles account for excellent electrochemical performance of the Ni-rich lithium cathode material. This study provided some new thought into synthesis of high performance fluorine doped single crystal Ni-rich lithium cathode materials. [Display omitted] •The single crystal morphology provides short migration path for Li+ ions.•F-doped into the cathode material triggers partial Ni3+ reduction to Ni2+.•Lithium ions migrate more smoothly in F-doped single crystal material.•Both F-doping and single crystal morphology account for excellent performance.