LaPO4-coated Li1.2Mn0.56Ni0.16Co0.08O2 as a cathode material with enhanced coulombic efficiency and rate capability for lithium ion batteriesElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra13233a

• Main Authors: Xie, Qingliang, Zhao, Chenhao, Hu, Zhibiao, Huang, Qi, Chen, Cheng, Liu, Kaiyu
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c5ra13233a

In this paper, pristine Li-rich layered oxide Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 porous microspheres have been successfully synthesized by a urea combustion method, and then coated with 1.0%, 2.0%, and 3.0 wt% LaPO 4 via a facile chemical precipitation route. The structures and morphologies of both pristine and LaPO 4 coated Li 1.2 Mn 0.54 Ni 0.16 Co 0.08 O 2 were investigated by X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HR-TEM). XPS data and FESEM demonstrate that the LaPO 4 was successfully coated on the surface of the Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 porous microspheres. Especially, the 2 wt% LaPO 4 coated-Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 demonstrates the best electrochemical performance. As lithium ion battery cathodes, the 2 wt% LaPO 4 coated sample, compared with the pristine one, has shown significantly improved electrochemical performances: the initial coulumbic efficiency improves from 78.81% to 84.76% at 0.1C and the rate compatibility increased from 70 mA h g −1 to a high capacity of 112.73 mA h g −1 at a current density of 5C. The analysis of d Q /d V plots and electrochemical impedance spectroscopy (EIS) demonstrate that the enhanced electrochemical performance is mainly attributed to the fact that the LaPO 4 coating layer can not only stabilize the cathode structure by reducing the loss of oxygen, but also protect the Li-rich cathodes by decreasing the side reactions of Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 with the electrolyte and lower the charge transfer resistance of the sample. Layered Li[Li 0.2 Mn 0.56 Ni 0.16 Co 0.08 ]O 2 porous microspheres have been successfully synthesized by a urea combustion method, and then coated with appropriate amount of LaPO 4 via a facile chemical precipitation route.