Mechanisms responsible for two possible electrochemical reactions in Li1.2Ni0.13Mn0.54Co0.13O2 used for lithium ion batteries
Abstract
Two electrochemical reactions are possible in regard to Li1.2Ni0.13Mn0.54Co0.13O2 (0.5Li2MnO3-0.5LiNi0.33Mn0.33Co0.33O2), viz, Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like reactions. The open circuit potential (OCP) and changes in crystal structure during the charge-discharge process of Li1.2Ni0.13Mn0.54Co0.13O2 were investigated to clarify the mechanism responsible for the two reactions. Li2MnO3 and LiNi0.33Mn0.33Co0.33O2 were separately prepared for the investigation, and the OCPs and crystal structures in these cathodes were measured and then compared with those for Li1.2Ni0.13Mn0.54Co0.13O2. The results obtained using X-ray diffraction (XRD) indicated that two phases existed in Li1.2Ni0.13Mn0.54Co0.13O2. The changes in crystal structure of the two phases during the charge-discharge process were similar to those in Li2MnO3 and LiNi0.33Mn0.33Co0.33O2. This indicated that two phases, viz, Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like, existed in Li1.2Ni0.13Mn0.54Co0.13O2. Li2MnO3-like, LiNi0.33Mn0.33Co0.33O2-like, and Li2MnO3-like phases were found to contribute mainly to electrochemical reactions in the low, middle, and high state of charge (SOC) ranges during the charge process from the results obtained using XRD and electrochemical measurements carried out on Li1.2Ni0.13Mn0.54Co0.13O2. In contrast, the Li2MnO3-like and LiNi0.33Mn0.33Co0.33O2-like phases mainly contributed to electrochemical reactions in the low and high SOC ranges during the discharge process. Furthermore, the high polarization and potential decay during the charge-discharge cycling of Li1.2Ni0.13Mn0.54Co0.13O2 were mainly attributed to the Li2MnO3-like phase.
- Publication:
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Journal of Solid State Chemistry France
- Pub Date:
- February 2018
- DOI:
- 10.1016/j.jssc.2017.10.024
- Bibcode:
- 2018JSSCh.258..225K
- Keywords:
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- Lithium ion battery;
- Lithium-rich layer-structured cathode;
- Potential decay;
- Cycle;
- Crystal structure