Investigation on the electrochemical activation process of Li1.20Ni0.32Co0.004Mn0.476O2

• Main Authors: Daichun Tang, Daotan Liu, Yanyan Liu, Zhenzhong Yang, Liquan Chen
• Format: Article
• Language: English
• Published: Elsevier 2014-08-01
• Series: Progress in Natural Science: Materials International
• Subjects: Lithium-rich; Electrochemical activation; Surface structure; STEM imaging
• Online Access: http://www.sciencedirect.com/science/article/pii/S1002007114000926

The lithium-rich layered oxides are one of the most attractive cathode materials for lithium-ion batteries. Here, two types of Li1.20Ni0.32Co0.004Mn0.476O2 were synthesized using Li2CO3 and LiOH as lithium sources. An electrochemical activation process occurs in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from Li2CO3 (LLO-1), while no obvious activation in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from LiOH (LLO-2) is observed. Via advanced scanning transmission electron microscopy (STEM), we found that Li2MnO3-like structure is rich in the surface region of LLO-2. The study provides a direct explanation for the electrochemical activation of lithium-rich materials. The sample with more LiMO2-like phase at the surface region shows a better cycling performance. It is likely that more LiMO2-like phase at the surface region could stabilize the interface and improve the cycling performance of the Li-rich cathode materials.