Wednesday, 1 June 2022: 12:00
West Meeting Room 109 (Vancouver Convention Center)
R. Baddour-Hadjean, J. P. Pereira-Ramos, and A. Bhatia (ICMPE-CNRS UMR7182)
Li-ion batteries (LIBs) have been widely used as power source for portable devices and are available for applications to electric vehicles, which demand high power, high energy, inexpensive and safe batteries1. Their continuous improvement is tightly bound to the understanding of Li (de)intercalation phenomena in electrode materials. The LiMn1.5Ni0.5O4 (LMNO) spinel is a promising cathode material for next generation LIBs since it offers a high voltage plateau at ∼
4.7 V vs. Li+/Li, a specific capacity of ~135 mAh g-1 leading to a high energy density of 700 Wh kg-1 (20 and 30% greater than LiCoO2 and LiFePO4, respectively). However, despite extensive research activities, little information is given about the atomic level variations during the electrochemical reaction of LMNO and the instability issues, particularly self-discharge phenomenon. For this purpose, Raman spectroscopy is a very appropriate tool to enrich the knowledge of the structure of Li intercalation compounds at the scale of the chemical bond, providing a better insight into the mechanisms governing the electrode performances2
In this work, we address for the first time the use of Raman spectroscopy to picture the redox mechanism involved in the disordered LMNO composite cathode in the 3.5-4.9 V voltage range. As shown in Fig. 1, the Raman spectra recorded during the charge-discharge cycle display rich and varying features, which are strongly associated with the changes in the transition metals valence states. A careful electrochemical and spectroscopic analysis allows identifying specific descriptors of the Ni2+/Ni3+/Ni4+ species in the Raman spectra and providing their relative ratio during the redox process. This combined approach demonstrates the efficiency of Raman spectroscopy to determine the state of charge (SOC) of the LMNO cathode. As a proof of concept, we demonstrate Raman spectroscopy is a fast and reliable tool to measure the self-discharge phenomenon in the spinel electrode.
References
1 J. M. Tarascon, M. Armand, Nature 414 (2001) 359.
2 R. Baddour-Hadjean, J. P. Pereira-Ramos, Chem. Rev. 110 (2010) 1278.
3 A.Bhatia, Y.D. Zrelli, J. P. Pereira-Ramos, R. Baddour-Hadjean, J. Mater. Chem. A 9 (2021) 13496
