Grain boundary transport in sputter-deposited nanometric thin films of lithium manganese oxide

Mürter, Juliane; Nowak, Susann; Hadjixenophontos, Efi; Joshi, Yug; Schmitz, Guido

doi:10.1016/j.nanoen.2017.11.038

Cited by 19 publications

(19 citation statements)

References 34 publications

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“…Required targets were prepared from powder (Sigma‐Aldrich CAS no. 12057‐17‐9) that was uniaxially pressed (500 MPa), followed by sintering at 900 °C for 10 h . For additional stability, the sintered powder cake was glued onto a metal disc of 80 mm diameter, using a conductive epoxy glue.…”

Section: Methodsmentioning

confidence: 99%

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

Joshi

Hadjixenophontos

Nowak

et al. 2018

Advanced Optical Materials

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a change in its optical constants during lithiation. However, a quantification of the optical properties and their tailoring via dis/charging has not been probed yet.The present study aims at the quantification of the optical constants, that is, the complex refractive index (CRI) and its change during intercalation by varying the lithium content of Li x Mn 2 O 4 from x = 0 to x = 1. Furthermore, an attempt is made to establish a link between this change in optical constants to the band structure of the material, learned from various sources. [11,15,[18][19][20][21] Similar characteristics have been reported for other electrochromic materials, such as Nb 2 O 5 , WO 3 , V 2 O 5 , and MoO 3, [22] which are known to change their optical properties, namely the real (n) and imaginary (k, or extinction coefficient) part of the CRI during an electrochemical reaction. In these materials, intercalation of charged species results in the generation of different electronic absorption bands in the optical spectrum or insertion of additional bound charges acting as harmonic oscillators. [22] For the present study, the reflection spectrum is measured at different stages of intercalation to clarify such electrochromic phenomenon. The measured spectra are evaluated to extract the CRI of the material for different lithium contents. Furthermore, an innovative method of recording the reflectance spectrum in situ during the electrochemical reaction is demonstrated (Figure 1c) that provides an additional time resolution to the spectrometry. Results Structural CharacterizationThe X-ray diffractogram (XRD) spectra of representative samples of LMO in the as-deposited and annealed states are shown in Figure 2a. No characteristic LMO diffraction peaks are observed for the as-deposited layer (bottom curve of Figure 2a). Only a small hump, observed at 61.98° (marked with *), could be due to the LMO structure corresponding to {440} planes. This reflection is very broad and shifted in comparison to the work of Wickhamt and Croft. [23] (JCP2 database) that predicts the position at 63.78°. The shape and the shift in the reflection suggest that the LMO layer is nanocrystalline and stressed, as it is usually the case for sputter-deposited layers.The optical response of lithium manganese oxide (LiMn 2 O 4 , LMO) on intercalation with Li ions is quantitatively characterized. For this purpose, a layer of LMO and a layer of platinum, acting as current collector/reflector, are deposited on oxidized silicon wafers. The active layer is structurally characterized using X-ray diffractogram and transmission electron microscopy. Well-defined intercalation states are prepared electrochemically and investigated by optical spectrometry in reflectance geometry. The measured dispersion curves are described by the Clausius-Mossotti dispersion equation to derive the complex refractive index as a function of wavelength and intercalation state. The observed variation of the effective resonant wavelength is consistent with the change in the band structure of LMO with l...

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Section: Methodsmentioning

confidence: 99%

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

Joshi

Hadjixenophontos

Nowak

et al. 2018

Advanced Optical Materials

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“…5(a) and (b), respectively. 39 The direct comparison clearly discovers that the modied defective Li 2 MnO 3Àd layers of this study outperforms the conventional LMO lms by at least a factor of two (stabilized capacity, see Fig. 5(b)).…”

Section: Electrochemical Characterizationmentioning

confidence: 54%

“…Finally, capacities observed in thin-lm electrodes amount typically to only 50-60% of the values achieved in powder electrodes with the same material. 23,26,34,38,39 In view of the aforementioned factors, we also measured conventional LMO layers produced under the same conditions of layer deposition as the layers of interest for a meaningful comparison. The capacity of these conventional LMO lms are presented as green data points and dashed green lines in Fig.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

High capacity rock salt type Li₂MnO_3−δthin film battery electrodes

et al. 2020

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“…Voltammograms were obtained for different individual LiMn 2 O 4 particles, of about 200 nm in diameter, supported on glassy carbon (GC), in aqueous media. Another recent work is that of Mürter et al [16], who analyzed the electrochemistry of LMO nanofilms with thicknesses ranging from 55 nm to 515 nm, composed of nanocrystals in organic solvents, and showed how film thickness determines the behavior of voltammograms. These are valuable steps for the rational design of electrode materials for Li-ion batteries.…”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this work is to use numerical simulations to obtain theoretical voltammograms for LiMn 2 O 4 single particles and thin films of nanometric size in connection with the experimental works of Tao et al [15] and Mürter et al [16], and analyze the relevance of the nanometric size of the particles for the voltammetric response of the system. The results will be also discussed in the framework of the theoretical predictions of Aoki et al [27].…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of cyclic voltammetry for lithium-ion intercalation in nanosized systems: finiteness of diffusion versus electrode kinetics

Gavilán-Arriazu

Mercer

Pinto

et al. 2020

J Solid State Electrochem

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The voltammetric behavior of Li + intercalation/deintercalation in/from LiMn 2 O 4 thin films and single particles is simulated, supporting very recent experimental results. Experiments and calculations both show that particle size and geometry are crucial for the electrochemical response. A remarkable outcome of this research is that higher potential sweep rates, of the order of several millivolts per second, may be used to characterize nanoparticles by voltammetry sweeps, as compared with macroscopic systems. This is in line with previous conclusions drawn for related single particle systems using kinetic Monte Carlo simulations. The impact of electrode kinetics and finite space diffusion on the reversibility of the process and the finiteness of the diffusion in ion Li / LiMn 2 O 4 (de)intercalation is also discussed in terms of preexisting modeling.

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Grain boundary transport in sputter-deposited nanometric thin films of lithium manganese oxide

Cited by 19 publications

References 34 publications

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

High capacity rock salt type Li₂MnO_3−δthin film battery electrodes

Numerical simulations of cyclic voltammetry for lithium-ion intercalation in nanosized systems: finiteness of diffusion versus electrode kinetics

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Grain boundary transport in sputter-deposited nanometric thin films of lithium manganese oxide

Cited by 19 publications

References 34 publications

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

Modulation of the Optical Properties of Lithium Manganese Oxide via Li‐Ion De/Intercalation

High capacity rock salt type Li2MnO3−δthin film battery electrodes

Numerical simulations of cyclic voltammetry for lithium-ion intercalation in nanosized systems: finiteness of diffusion versus electrode kinetics

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High capacity rock salt type Li₂MnO_3−δthin film battery electrodes