In situ synchrotron X-ray studies of LiNi1-x-yCoyMnxO2 cathode materials

Synchrotron X-ray radiation was utilized to study the structural change of layer-structured LiNi0.6Co0.25Mn0.15O2 during cycling. Unlike the LiNiO2 or LiCoO2 systems, there was no new H2 phase formed during the whole charge-discharge process. With Li-deintercalated from LiNi0.6Co0.25Mn0.15O2, a single-phase reaction prevailed. It was reveled that both the a and c axes varied with different Li contents in this material system. Besides, the volumetric change after the first charge was only 4%; which was much smaller compared with those of LiNiO2, LiCoO2, and LiMnO2 electrode materials. As a result, a better structure stability was derived. (c) 2007 The Electrochemical Society.