Epoxy-functionalized silane grafting enhances the cycling performances of Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials

Abstract

Epoxy-functionalized silane (KH560) modified Li1.2Ni0.13Co0.13Mn0.54O2 materials are prepared by a facile chemical grafting method for the first time. X-ray diffraction confirms that the crystal structure of Li1.2Ni0.13Co0.13Mn0.54O2 is not affected by the KH560 modification. Scanning electron microscopy and transmission electron microscopy results prove that KH560 is homogeneously grafted on the Li1.2Ni0.13Co0.13Mn0.54O2 surface with a thickness of 3–5 nm. The electrochemical tests reveal that the 1.0 wt% KH560 modified Li1.2Ni0.13Co0.13Mn0.54O2 cathodes retain 92.88% (1 C) and 98.24% (5 C) capacity retentions after 100 cycles, respectively, far higher than 83.09% (1 C) and 50.68% (5 C) of the pristine. The improved cycling performances are mainly attributed to the fact that the X-O-M bonds stabilize the surface oxygen and resist the parasitic reactions during cycling, which further can suppress the structure degradation and the impedance increase. This work provides a facile and effective modification method to optimize the interfacial structures of Li1.2Ni0.13Co0.13Mn0.54O2 and/or other cathode materials.