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Title: X-ray nanotomography analysis of the microstructural evolution of LiMn 2O 4 electrodes

Abstract

One of the greatest challenges for advancing lithium-ion battery (LIB) technology is to minimize cell degradation during operation for long-term stability. To this end, it is important to understand how cell performance during operation relates to complex LIB microstructures. In this report, transmission X-ray microscopy (TXM) nanotomography is used to gain quantitative three-dimensional (3D) microstructure-performance correlations of LIB cathodes during cycling. The 3D microstructures of LiMn 2O 4 (LMO) electrodes, cycled under different conditions, including cycle number, operating voltage, and temperature, are characterized via TXM and statistically analyzed to investigate the impact of cycling conditions on the electrode microstructural evolution and cell performance. It is found that the number of cracks formed within LMO particles correlated with capacity fade. For the cell cycled at elevated temperatures, which exhibits the most severe capacity fade among all cells tested, mechanical cracking observed in TXM is not the only dominant contributor to the observed degradation. Mn 2+ dissolution, as verified by detection of Mn on the counter electrode by energy dispersive spectrometry, also contributed. The current work demonstrate 3D TXM nanotomography as a powerful tool to help probe in-depth.

Authors:
 [1];  [2];  [3];  [4];  [5];  [4];  [1];  [1]
  1. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
  2. Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biological Engineering; Central South Univ., Changsha (China). College of Chemistry and Chemical Engineering
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II); Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering
  4. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  5. Northwestern Univ., Evanston, IL (United States). Dept. of Chemical and Biological Engineering
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1436252
Report Number(s):
BNL-203494-2018-JAAM
Journal ID: ISSN 0378-7753
Grant/Contract Number:
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Power Sources
Additional Journal Information:
Journal Volume: 360; Journal Issue: C; Journal ID: ISSN 0378-7753
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Liu, Zhao, Han, Kai, Chen-Wiegart, Yu-chen Karen, Wang, Jiajun, Kung, Harold H., Wang, Jun, Barnett, Scott A., and Faber, Katherine T. X-ray nanotomography analysis of the microstructural evolution of LiMn2O4 electrodes. United States: N. p., 2017. Web. doi:10.1016/j.jpowsour.2017.06.027.
Liu, Zhao, Han, Kai, Chen-Wiegart, Yu-chen Karen, Wang, Jiajun, Kung, Harold H., Wang, Jun, Barnett, Scott A., & Faber, Katherine T. X-ray nanotomography analysis of the microstructural evolution of LiMn2O4 electrodes. United States. doi:10.1016/j.jpowsour.2017.06.027.
Liu, Zhao, Han, Kai, Chen-Wiegart, Yu-chen Karen, Wang, Jiajun, Kung, Harold H., Wang, Jun, Barnett, Scott A., and Faber, Katherine T. Sat . "X-ray nanotomography analysis of the microstructural evolution of LiMn2O4 electrodes". United States. doi:10.1016/j.jpowsour.2017.06.027.
@article{osti_1436252,
title = {X-ray nanotomography analysis of the microstructural evolution of LiMn2O4 electrodes},
author = {Liu, Zhao and Han, Kai and Chen-Wiegart, Yu-chen Karen and Wang, Jiajun and Kung, Harold H. and Wang, Jun and Barnett, Scott A. and Faber, Katherine T.},
abstractNote = {One of the greatest challenges for advancing lithium-ion battery (LIB) technology is to minimize cell degradation during operation for long-term stability. To this end, it is important to understand how cell performance during operation relates to complex LIB microstructures. In this report, transmission X-ray microscopy (TXM) nanotomography is used to gain quantitative three-dimensional (3D) microstructure-performance correlations of LIB cathodes during cycling. The 3D microstructures of LiMn2O4 (LMO) electrodes, cycled under different conditions, including cycle number, operating voltage, and temperature, are characterized via TXM and statistically analyzed to investigate the impact of cycling conditions on the electrode microstructural evolution and cell performance. It is found that the number of cracks formed within LMO particles correlated with capacity fade. For the cell cycled at elevated temperatures, which exhibits the most severe capacity fade among all cells tested, mechanical cracking observed in TXM is not the only dominant contributor to the observed degradation. Mn2+ dissolution, as verified by detection of Mn on the counter electrode by energy dispersive spectrometry, also contributed. The current work demonstrate 3D TXM nanotomography as a powerful tool to help probe in-depth.},
doi = {10.1016/j.jpowsour.2017.06.027},
journal = {Journal of Power Sources},
number = C,
volume = 360,
place = {United States},
year = {Sat Jun 17 00:00:00 EDT 2017},
month = {Sat Jun 17 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • Here in this study, synchrotron X-ray nano-computed tomography at Advanced Photon Source in Argonne National Laboratory has been employed to reconstruct real 3D active particle morphology of LiMn 2O 4 (LMO) commonly used in lithium-ion batteries (LIBs). For the first time, carbon-doped binder domain (CBD) has been included in the electrode structure as a 108 nm thick uniform layer using image processing technique. With this unique model, stress generated inside four LMO particles with a uniform layer of CBD has been simulated, demonstrating its strong dependence on local morphology (surface concavity and convexity), and the mechanical properties of CBD suchmore » as Young’s modulus. Specifically, high levels of stress have been found in vicinity of particle’s center or near surface concave regions, however much lower than the material failure limits even after discharging at the rate as high as 5C. On the other hand, the stress inside CBD has reached its mechanical limits when discharged at 5C, suggesting that it can potentially lead to failure by plastic deformation. The findings in this study highlight the importance of modeling LIB active particles with CBD and its appropriate compositional design and development to prevent the loss of electrical connectivity of the active particles from the percolated solid network and power losses due to CBD failure.« less
  • The in situ XAFS technique has been applied for the first time to reveal variations in the local structures of Mn atoms during the charge-discharge process of LiMn{sub 2}O{sub 4}, Li(Mn{sub 1.93}Li{sub 0.07})O{sub 4}, and Li(Mn{sub 1.85}Li{sub 0.7})O{sub 4} cathode materials of lithium-ion secondary batteries. It has been demonstrated that the valence state of manganese is in a linear correlation with the peak energy of the Mn K-edge XANES spectrum. EXAFS analysis disclosed the {sup 3}+ Mn{sup 4}+ coexistence of Mn and in LiMn{sub 2}O{sub 4}, with two distinct Mn-O bond distances of 1.98 and 1.88{angstrom} for the Mn{sup 3+}.
  • Fourier transform infrared spectroscopy (FTIR) has been applied to the study of oxide insertion compounds used in rechargeable lithium batteries. The mechanisms responsible for capacity fading during normal cycling of LiMn{sub 2}O{sub 4} cells in both the 3 and 4 V regions were determined by examination of spectra obtained from electrodes following 25 cycles at charge and discharge rates of C/6. In the 3 V region, electroactive material becomes electronically disconnected from the rest of the electrode due to fracture of the oxide particles and/or expansion and contraction of the active material during the cubic-to-tetragonal phase transformation. In the uppermore » voltage region, the active electrode material is gradually converted to a lower voltage defect spinel phase via dissolution of manganese in the electrolyte.« less
  • The reaction of Re{sub 2}O{sub 7} with XeF{sub 6} in anhydrous HF provides a convenient route to high-purity ReO{sub 2}F{sub 3}. The fluoride acceptor and Lewis base properties of ReO{sub 2}F{sub 3} have been investigated leading to the formation of [M][ReO{sub 2}F{sub 4}] [M = Li, Na, Cs, N(CH{sub 3}){sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{sub 3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 2}F{sub 3}(CH{sub 3}CN). The ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and Re{sub 3}O{sub 6}F{sub 10{sup {minus}} anions and the ReO{sub 2}F{sub 3}(CH{sub 3}CN) adduct have been characterized in the solidmore » state by Raman spectroscopy, and the structures [Li][ReO{sub 2}F{sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{approximately}3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN have been determined by X-ray crystallography. The structure of ReO{sub 2}F{sub 4}{sup {minus}} consists of a cis-dioxo arrangement of Re-O double bonds in which the Re-F bonds trans to the oxygen atoms are significantly lengthened as a result of the trans influence of the oxygens. The Re{sub 2}O{sub 4}F{sub 7}{sup {minus}} and Re{sub 3}O{sub 6}F{sub 10}{sup {minus}} anions and polymeric ReO{sub 2}F{sub 3} are open chains containing fluorine-bridged ReO{sub 2}F{sub 4} units in which each pair of Re-O bonds are cis to each other and the fluorine bridges are trans to oxygens. The trans influence of the oxygens is manifested by elongated terminal Re-F bonds trans to Re-O bonds as in ReO{sub 2}F{sub 4}{sup {minus}} and by the occurrence of both fluorine bridges trans to Re-O bonds. Fluorine-19 NMR spectra show that ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and ReO{sub 2}F{sub 3}(CH{sub 3}CN) have cis-dioxo arrangements in CH{sub 3}CN solution. Density functional theory calculations at the local and nonlocal levels confirm that the cis-dioxo isomers of ReO{sub 2}F{sub 4}{sup {minus}} and ReO{sub 2}F{sub 3}(CH{sub 3}CN), where CH{sub 3}CN is bonded trans to an oxygen, are the energy-minimized structures. The adduct ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN was obtained by hydrolysis of ReO{sub 2}F{sub 3}(CH{sub 3}CN), and was shown by X-ray crystallography to have a facial arrangement of oxygen atoms on rhenium.« less
  • An alcoholysis exchange between tris(hydroxymethyl)ethane (THME-H{sub 3}) or tris(hydroxymethyl)propane (THMP-H{sub 3}) and group IV metal isopropoxides yields compounds of the general formula (THMR){sub 2}M{sub 4}(OCHMe{sub 2}){sub 10}[M = Ti (R = E, 1; P, 2); Zr (R = E, 3; P, 4)]. 1 and 2 are formed in toluene, at ambient glovebox temperatures, and adopt a typical fused-M{sub 3}O{sub 12} structure where each titanium atom is surrounded by six oxygens in a slightly distorted face-shared bioctahedral arrangement. All of the oxygens of the central core are from the THMR ligand, present as {mu}-O and {mu}{sub 3}-O oxygen bridges. Generation ofmore » 3 or 4 requires heating in toluene at reflux temperatures. The zirconium atoms of 3 possess an extremely distorted edge-shared bioctahedral geometry where the central core consists of a Zr{sub 4}O{sub 8} ring (eight oxygens: six from THME ligands and two from isopropoxide ligands). Each of the zirconium atoms is six-coordinated with four bridging oxygens and two terminal isopropoxide ligands. Spincast deposited films generated from toluene solutions of 1 and 3 indicate that increased uniformity of the films and decreased hydrolysis occur in comparison to the cases of Ti(OCHMe{sub 2}){sub 4}, 5, and [Zr(OCHMe{sub 2}){sub 4}{center_dot}HOCHMe{sub 2}]{sub 2}, 6, respectively.« less