New positive electrode materials operating at higher voltage (such as LiNi0.5Mn1.5O4 - LNMO), hold great promise for the next generation of high energy lithium-ion batteries (LIB), but show a rapid degradation of their performance upon cycling, which limits their immediate development. One major problem associated to the high operational voltage of such electrode materials, is the pronounced oxidation of standard electrolytes used in LIBs and the concomitant dissolution of the LNMO material and the possible impact on the negative electrode (cross-talking). Through the development of a set of operando diagnostic techniques, this work aims at establishing during the charge/discharge cycles the correlation between the structural changes in LNMO, the interfacial processes (electrolyte oxidation, formation of Cathode Electrolyte Interphase: CEI, LNMO transition metal dissolution) and the cross-talk process depending on the electrodes/separator assembly.We will introduce in this presentation our recent developments on operando SHINERS1 (Shell-Isolated Nanoparticles-Enhanced Raman Spectroscopy) to track the dynamic of the interfacial processes2 at LNMO electrodes3. We will also present how temporally and spatially resolved confocal fluorescence and X-Ray spectroscopy measurements implemented operando on the edge of the electrode assembly can be used to quantify the LNMO dissolution upon cycling. The electrolyte composition and the role of electrolyte additives to stabilize the high-voltage cathode / electrolyte interface will be discussed.
Li, J.F., Huang, Y.F., Ding, Y., Yang, Z.L., Li, S.B., Zhou, X.S., Fan, F.R., Zhang, W., Zhou, Z.Y., Wu, D.Y., et al. (2010). Shell-isolated nanoparticle-enhanced Raman spectroscopy. Nature 464, 392–395.Gajan, A., Lecourt, C., Torres Bautista, B.E., Fillaud, L., Demeaux, J., and Lucas, I.T. (2021). Solid Electrolyte Interphase Instability in Operating Lithium-Ion Batteries Unraveled by Enhanced-Raman Spectroscopy. ACS Energy Lett., 1757–1763.Dumaz, P., Rossignol, C., Mantoux, A., Sergent, N., and Bouchet, R. (2020). Kinetics analysis of the electro-catalyzed degradation of high potential LiNi0,5Mn1,5O4 active materials. Journal of Power Sources 469, 228337.
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