Local Study of Lithiation and Degradation Paths in LiMn2O4 Battery Cathodes: Confocal Raman Microscopy Approach

Abstract

Lithium manganese-based cathodes are widely used in rechargeable batteries due to their low cost, safety, and ecological stability. On the other hand, fast capacity fade occurs in LiMn 2 O 4 mainly because of the induced manganese dissolution and formation of additional phases. Confocal Raman microscopy provides many opportunities for sensitive and spatially resolved structural studies of micro-and nanoscale phenomena. Here, we demonstrate advantages of confocal Raman spectroscopy approach for uncovering the mechanisms of lithiation/delithiation and degradation in LiMn 2 O 4 commercial cathodes. The analysis of Raman spectra for inspecting local lithiation state and phase composition is proposed and exploited for the visualization of the inhomogeneous distribution of lithium ions. The cycling of cathodes is shown to be followed by the formation and dissolution of the Mn 3 O 4 phase and local disturbance of the lithiation state. These processes are believed to be responsible for the capacity fade in the commercial batteries.

Efficiency Threshold of Carbon Layer Growth in Li4Ti5O12/C Composites

“…Also such an approach can be used for study of the electrode material degradation, induced by ion dissolution and/or undesirable structural transformations during cycling. 40 Chemical bonding analysis.-Besides morphological study, XPS can be also used for C@LTO interface characterization by chemical bonding analysis. For all the examined samples, C1s band was decomposed into five peaks ( Figure 5).…”

Correlative Confocal Raman and Scanning Probe Microscopy in the Ionically Active Particles of LiMn2O4 Cathodes

“…According to our previous studies, a few peaks of the Raman spectrum can be used to determine the lithiathion state and phase composition of LMO [32]. At a nominal composition Li 0.61 Mn 2 O 4 , Raman spectra consist of 5 peaks: 310 cm −1 , 490 cm −1 , and 630 cm −1 related to the F 2 lattice vibrational modes and peaks at 565 cm −1 and 592 cm −1 related to the A 1 modes [32]. Details of the Raman spectra are discussed in [32].…”

“…At a nominal composition Li 0.61 Mn 2 O 4 , Raman spectra consist of 5 peaks: 310 cm −1 , 490 cm −1 , and 630 cm −1 related to the F 2 lattice vibrational modes and peaks at 565 cm −1 and 592 cm −1 related to the A 1 modes [32]. Details of the Raman spectra are discussed in [32]. Here, to construct confocal Raman maps, the A 1 peak at 592 ± 4 cm −1 , which indicates the local lithiation state, was used (Figure 1b) as well as the peak at 660 ± 3 cm −1 associated with the A 1g mode of Mn 3 O 4 (Figure 1b).…”

“…The Raman signal was collected at each scanning point for 25 s. The obtained spectra were fitted by superpositions of Lorentzian functions. Positions and intensity of individual peaks determined after the fitting were plotted as pseudo-color maps with the help of the Gwyddion software (Department of Nanometrology, 2.53, Brno, Czech Republic) following a procedure described in our earlier publication [32].…”

Statistical Raman spectroscopy characterization of carbon additive in low‐C composites: Toward industrial quality control

“…In either cases, researchers collect (or mine) some amount of data (the more, the better) for further analysis of kinetics or nonuniformity. Spatially resolved RS date can be treated in two ways—either via sample mapping (see, for example, Panitz and Novák, O'Neill et al, Slautin, Alikin, Rosato, Pelegov, Shur, and Kholkin, and Migge, Sandmann, Rahner, Dietz, and Plieth) or in the form of statistical analysis. The first one describes Raman microscopy approach, whereas the second—sRS.…”