Synthesis of full concentration gradient, cathode studied by high energy X-ray diffraction

Abstract

Nickel-rich metal oxides have been widely pursued as promising cathode materials for high energy density lithium-ion batteries. Nickel-rich lithium transition metal oxides can deliver a high specific capacity during cycling, but can react with non-aqueous electrolytes. In this work, we have employed a full concentration gradient (FCG) design to provide a nickel-rich core to deliver high capacity and a manganese-rich outer layer to provide enhanced stability and cycle life. In situ high-energy X-ray diffraction was utilized to study the structural evolution of oxides during the solid-state synthesis of FCG lithium transition metal oxide with a nominal composition of LiNi0.6Mn0.2Co0.2O2. We found that both the pre-heating step and the sintering temperature were critical in controlling phase separation of the transition metal oxides and minimizing the content of Li2CO3 and NiO, both of which deteriorate the electrochemical performance of the final material. The insights revealed in this work can also be utilized for the design of other nickel-rich high energy-density cathode materials. (C) 2016 Elsevier Ltd. All rights reserved.Research was funded by U.S. Department of Energy (DOE), Vehicle Technologies Office. Support from David Howell and Peter Faguy of the U.S. DOE's Office of Vehicle Technologies Program is gratefully acknowledged. Argonne National Laboratory is operated for the US Department of Energy by UChicago Argonne, LLC, under contract DE-AC02-06CH11357. Use of the Advanced Photon Source (APS) and the Center for Nanoscale Materials, including resources in the Electron Microscopy Center, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract no. DE-AC02-06CH11357. This work was also supported by the Global Frontier R&D Program (2013M3A6B1078875) on Center for Hybrid Interface Materials (HIM) funded by the Ministry of Science, ICT & Future Planning and by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2014R1A2A1A13050479)