Improvement of Electrochemical Performance of Li-Rich Cathode Material with Specific Morphology for Lithium Ion Batteries

Li-rich cathode materials (Li₂MnO₃-LiMO₂) have been reported as promising cathode materials since they can deliver high specific capacity and perform with a very good rate capability [1]. Considering the relatively high content of Mn and low content of Ni and Co, Li[Li_0.2Mn_0.56Ni_0.16Co_0.08]O₂which is a solid solution between Li₂MnO₃ and LiMn_0.4Ni_0.4Co_0.2O₂ with mole ratio of 5:5,  fulfills the requirements of a next-generation cathode material very well: low cost, higher energy density and safe. However, high cut-off voltages of up to 4.6-4.8 V are required during charge to obtain high specific capacity as well as high energy.

The morphology of a material has obvious influence to its electrochemical properties, especially for nanostructure materials. In this work, the specific morphology of Li[Li_0.2Mn_0.56Ni_0.16Co_0.08]O₂, has been successfully synthesized by high temperature annealing assisted by molten salt. XRD characterization proved that it belongs to the R-3m layered structure with the monoclinic Li₂MnO₃-like (C2/m) super lattice. The electrochemical experiments proved that the specific structure like spherical (Figure 1A) or porous (Figure 1B) could increase the rate capability and improve the cycle performance [2]. The morphology control during synthesis is a significant way to improve the performance of Li-rich cathode in lithium-ion batteries, and is a promising candidate for the realization of high voltage lithium and lithium-ion batteries.

Reference

[1] J. Li, R. Klöpsch, M. C. Stan, S. Nowak, M. Kunze, M. Winter, and S. Passerini. J. Power Sources, 196 (2011) 4821

[2] X. He, J. Wang, R. Klöpsch, S. Krueger, H. Jia, H. Liu, B. Vortmann, and J. Li. Nano Research, 7 (2014) 110.

[3] J. Wang, X. He, R. Klöpsch, S. Wang, B. Hoffmann, S. Jeong, Y. Yong and J. Li. Energy Technology, 2 (2014) 188