Effect of titanium addition as nickel oxide formation inhibitor in nickel-rich cathode material for lithium-ion batteries

Among high capacity cathodes, LiNi0.8Co0.15Al0.05O2 has a high capacity and stable electrochemical performance, although it suffers from degradation upon cycling and aging as a result of the formation of inactive NiO on the surface edges. In this study, the role of Ti, which partially replaces Ni in the transition metal layer that is in particular intended to surface region not in bulk of LiNi0.8Co0.15Al0.05O2, is investigated on the electrochemical performance and interfacial phenomena using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and X-ray diffraction analyses before and after electrochemical cycling. As a result, formation of NiO inactive phase is inhibited for the Ti-doped LiNi0.8Co0.015Al0.05O2, so that the electrode could deliver higher capacity upon cycling test. Further electrochemical impedance analysis is performed to understand the interfacial behavior of Ti-doped LiNi0.8Co0.15Al0.05O2 (LiNi0.80Co0.15Al0.02Ti0.03O2). (C) 2015 Elsevier B.V. All rights reserved.This research was supported by the Global Excellent Technology Innovation of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20135020900010) and 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