Enhanced rate performance and cycle stability of LiNi0.6Co0.2Mn0.2O2 at high cut-off voltage by Li6.1La3Al0.3Zr2O12 surface modification

• Published in: Applied surface science 2020-09, Vol.524, p.146556, Article 146556
• Main Authors: Cheng, Zhiyan, Lv, Fei, Xu, Ning, Liu, Ying, Xie, Huan, Wu, Mengtao, Ma, Yu, Zhang, Yufei, Chen, Li
• Format: Article
• Language: English
• Subjects: High ionic conductivity; In-situ wet coating and synchronous lithiation strategy; Li6.1La3Al0.3Zr2O12; LiNi0.6Co0.2Mn0.2O2
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146556

LLAZO modified NCM were prepared by the in-situ wet coating hydroxide precursor and synchronous lithiation strategy, which exists excellent cyclic stability and rate performance. [Display omitted] •Fast ion conductor Li6.1La3Al0.3Zr2O12 nano flakes shell are cladded onto Ni-rich NCM surface.•An in-situ wet coating hydroxide precursor and synchronous lithiation strategy is used to the surface modification.•Highest discharge capacity, best cycle stability and rate performance are achieved after LLAZO modification.•1 wt% LLAZO modified NCM exhibits the best cycle stability at 25℃ and 50℃. A stable surface structure is vital for Ni-rich cathode materials to achieve an excellent electrochemical performance, especially rate performance and cyclic stability. In this work, Li6.1La3Al0.3Zr2O12 (LLAZO) modified LiNi0.6Co0.2Mn0.2O2 (NCM) was successfully synthesized via in-situ wet coating and synchronous lithiation strategy. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy with EDS element mapping and transmission electron microscopy confirm the existence of LLAZO on the surface of NCM. According to the results, the 1 wt% LLAZO modified NCM (1-NCM) delivers a reversible capacity of 165.5 mAh g−1 at 2C from 2.7 to 4.5 V at 25℃, and the capacity retention rate is as high as 84.6%, whereas NCM delivers only 141.5 mAh g−1 and 54.7%, respectively. Furthermore, the 1-NCM delivers higher rate capacities of 172mAh g−1 at 1C and 125 mAh g−1 at 10C than those of NCM (162 and 102 mAh g−1), respectively. The enhanced electrochemical performance of LLAZO modified NCM is mainly due to: (1) the structure of NCM host is stabilized by LLAZO shell; (2) Li+ transport speed is enhanced on NCM surface after LLAZO modification. It is hopeful for LLAZO or others materials with higher ionic conductivity to enhance the electrochemical performance of Ni-rich cathode materials.