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19. Characterization of Li Diffusion and Solid Electrolyte Interface for Li4Ti5O12 Electrode Cycled with an Organosilicon Additive Electrolyte.

Author

Ma, Miaomiao, Mansour, Azzam N., Ko, Jonathan K., Waller, Gordon H., and Hendricks, Christopher E.

Subjects
SOLID electrolytes, KIRKENDALL effect, ELECTROLYTES, TITANATES, NEGATIVE electrode, X-ray photoelectron spectroscopy, ELECTRODES, LITHIUM-ion batteries
Abstract

The use of lithium titanate (Li4Ti5O12, LTO) for the negative electrode in lithium ion batteries has attracted enormous attention owing to its fast charging capability, high power, safe operating voltage window and stable structure ("zero strain") during cycling. Researchers have investigated the formation of the solid electrolyte interface (SEI) of the LTO electrode, which prevents gassing issue and leads to longer cycle life. In this study, the solid-state diffusion property of LTO at room temperature was characterized using AC impedance spectroscopy at different states of charge (SOC) during charge and discharge to reveal the dependency of the lithium diffusion coefficient on SOC. Meanwhile the formation and growth of the solid electrolyte interface (SEI) on the LTO electrode using an electrolyte containing Silatronix OS3® additive were investigated using X-ray photoelectron spectroscopy (XPS). The composition of the SEI and its evolution due to cycling with the OS3® additive was compared to that with a commercial electrolyte. Half-cell coin cells of LTO vs lithium metal were formed and cycled at room temperature for over 200 cycles, where the resistance increase, as measured by impedance spectroscopy, is correlated to the SEI growth. Electrode samples were analyzed in the pristine state, after formation, and after 200 cycles. XPS results showed that a thin layer of SEI is formed during the first two formation cycles and the composition of the SEI on the surface of the LTO electrode varied with increasing cycle number. Based on the escape depths of Ti 3 s and Ti 2p regions, the SEI after formation is thicker than 5.5 nm but is less than 7.0 nm for both the OS3® and A7 electrolytes. Based on Ar-ion depth profiling, the SEI thickness in terms of the equivalent thickness of SiO2 after 200 cycles in coin cell configuration is estimated to be near 14 nm for both the OS3® and A7 electrolytes. A much higher fluorine content (F 1s peak) was found in the SEI formed with the OS3® electrolyte than the SEI formed with the commercial A7 electrolyte. [ABSTRACT FROM AUTHOR]

Published
2020
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22. Probing the Electrode-Electrolyte Interface in Cycled LiNi[subscript0.5]Mn[subscript 1.5]O[subscript 4] by XPS Using Mg and Synchrotron X-rays

Author

Mansour, Azzam N., Quinlan, Ronald A., Kwabi, David Gator, Lu, Yi-Chun, Shao-Horn, Yang, Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Kwabi, David Gator, Lu, Yi-Chun, and Shao-Horn, Yang

Abstract

X-ray photoelectron spectroscopy (XPS) was used to investigate the surface chemistry of high voltage spinel, LiNi0.5Mn1.5O4 (LNMO) positive electrodes cycled 5 and 10 times in Li-cells with 1 M LiPF6 in (3:7) EC:DMC. The XPS spectra were collected using conventional Mg X-rays with energy of 1253.6 eV as well as synchrotron X-rays with energies of 2493.6 and 3498.4 eV in order to examine the depth distribution of various surface chemical species induced during cycling. The XPS spectra revealed a 5 – 10 nm surface layer of organic and LixPFyOz-type species formed as result of electrolyte decomposition, and a comparatively thinner layer composed of transition metal fluorides and LiF. These results suggest that electrolyte decomposition is a major contributor to parasitic reactions in LNMO battery electrochemistry. Limiting electrolyte decomposition with the use of solvents with wide electrochemical stability windows thus comprises a promising strategy for ensuring the practical feasibility of high voltage spinel materials in future Li-ion systems., National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award number DMR-0819762), United States. Dept. of Energy. Office of FreedomCAR and Vehicle Technologies(contract number DE-AC03-76SF00098), Lawrence Berkeley National Laboratory, United States. Dept. of Energy. Office of Basic Energy Sciences (contract number DE-AC02-98CH10886)

Published
2016

24. XPS Investigation of the Electrolyte Induced Stabilization of LiCoO[subscript 2] and 'AIPO[subscript 4]'-Coated LiCoO[subscript 2] Composite electrodes

Author

Quinlan, Ronald A., Mansour, Azzam N., Lu, Yi-Chun, Kwabi, David Gator, Shao-Horn, Yang, Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Electrochemical Energy Laboratory, Lu, Yi-Chun, Kwabi, David Gator, and Shao-Horn, Yang

Abstract

The “AlPO[subscript4]” coating has been shown to improve the electrochemical performance of LiCoO2 batteries. We previously showed that the “AlPO[subscript4]” coating promotes the formation of metal fluorides, which could act as a stable surface film and protect LiCoO[subscript2] from continuous degradation upon cycling. In this work, we removed the fluorine source in the LiPF[subscript6] salt by using the LiClO[subscript4] salt and investigated the effectiveness of the “AlPO[subscript4]” coating. Interestingly, the “AlPO[subscript4]” coating was found to improve the voltage efficiency and capacity retention when cycling in the LiPF[subscript6] electrolyte, but was detrimental when cycling in the LiClO[subscript4] electrolyte. XPS revealed that the “AlPO[subscript4]” coating promotes the formation of metal fluoride in both electrolytes, with the surface film formed in LiClO4 being more electrically resistive compared to that formed in LiPF[subscript6]. The source of fluorine in the coated electrode cycled in LiPF[subscript6] is largely attributed to the LiPF[subscript6] salt whereas the source of fluorine in the coated electrode cycled in LiClO[subscript4] is the binder PVDF. We believe that the coating could react with HF impurity in the LiPF[subscript6] electrolyte or from the binder PVDF and form stable metal fluoride films on the surface., National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award number DMR-0819762), United States. Department of Energy. Office of FreedomCAR and Vehicle Technologies (contract no. DE-AC03-76SF00098), United States. Department of Energy. Office of Basic Energy Sciences (contract no. DE-AC02-98CH10886)

Published
2015

25. Probing the Electrode-Electrolyte Interface in Cycled LiNi[subscript0.5]Mn[subscript 1.5]O[subscript 4] by XPS Using Mg and Synchrotron X-rays

Author

Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Kwabi, David Gator, Lu, Yi-Chun, Shao-Horn, Yang, Mansour, Azzam N., Quinlan, Ronald A., Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Kwabi, David Gator, Lu, Yi-Chun, Shao-Horn, Yang, Mansour, Azzam N., and Quinlan, Ronald A.

Abstract

X-ray photoelectron spectroscopy (XPS) was used to investigate the surface chemistry of high voltage spinel, LiNi0.5Mn1.5O4 (LNMO) positive electrodes cycled 5 and 10 times in Li-cells with 1 M LiPF6 in (3:7) EC:DMC. The XPS spectra were collected using conventional Mg X-rays with energy of 1253.6 eV as well as synchrotron X-rays with energies of 2493.6 and 3498.4 eV in order to examine the depth distribution of various surface chemical species induced during cycling. The XPS spectra revealed a 5 – 10 nm surface layer of organic and LixPFyOz-type species formed as result of electrolyte decomposition, and a comparatively thinner layer composed of transition metal fluorides and LiF. These results suggest that electrolyte decomposition is a major contributor to parasitic reactions in LNMO battery electrochemistry. Limiting electrolyte decomposition with the use of solvents with wide electrochemical stability windows thus comprises a promising strategy for ensuring the practical feasibility of high voltage spinel materials in future Li-ion systems., National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award number DMR-0819762), United States. Dept. of Energy. Office of FreedomCAR and Vehicle Technologies(contract number DE-AC03-76SF00098), Lawrence Berkeley National Laboratory, United States. Dept. of Energy. Office of Basic Energy Sciences (contract number DE-AC02-98CH10886)

Published
2017

26. XPS Investigation of the Electrolyte Induced Stabilization of LiCoO[subscript 2] and 'AIPO[subscript 4]'-Coated LiCoO[subscript 2] Composite electrodes

Author

Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Electrochemical Energy Laboratory, Lu, Yi-Chun, Kwabi, David Gator, Shao-Horn, Yang, Quinlan, Ronald A., Mansour, Azzam N., Massachusetts Institute of Technology. Department of Mechanical Engineering, Massachusetts Institute of Technology. Electrochemical Energy Laboratory, Lu, Yi-Chun, Kwabi, David Gator, Shao-Horn, Yang, Quinlan, Ronald A., and Mansour, Azzam N.

Abstract

The “AlPO[subscript4]” coating has been shown to improve the electrochemical performance of LiCoO2 batteries. We previously showed that the “AlPO[subscript4]” coating promotes the formation of metal fluorides, which could act as a stable surface film and protect LiCoO[subscript2] from continuous degradation upon cycling. In this work, we removed the fluorine source in the LiPF[subscript6] salt by using the LiClO[subscript4] salt and investigated the effectiveness of the “AlPO[subscript4]” coating. Interestingly, the “AlPO[subscript4]” coating was found to improve the voltage efficiency and capacity retention when cycling in the LiPF[subscript6] electrolyte, but was detrimental when cycling in the LiClO[subscript4] electrolyte. XPS revealed that the “AlPO[subscript4]” coating promotes the formation of metal fluoride in both electrolytes, with the surface film formed in LiClO4 being more electrically resistive compared to that formed in LiPF[subscript6]. The source of fluorine in the coated electrode cycled in LiPF[subscript6] is largely attributed to the LiPF[subscript6] salt whereas the source of fluorine in the coated electrode cycled in LiClO[subscript4] is the binder PVDF. We believe that the coating could react with HF impurity in the LiPF[subscript6] electrolyte or from the binder PVDF and form stable metal fluoride films on the surface., National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (award number DMR-0819762), United States. Department of Energy. Office of FreedomCAR and Vehicle Technologies (contract no. DE-AC03-76SF00098), United States. Department of Energy. Office of Basic Energy Sciences (contract no. DE-AC02-98CH10886)

Published
2017

28. Structural Changes of Cobalt-Based Perovskites upon Water Oxidation Investigated by EXAFS

Author

Risch, Marcel, Grimaud, Alexis, May, Kevin J., Stoerzinger, Kelsey A., Chen, Tina J., Mansour, Azzam N., and Shao-Horn, Yang

Abstract

While many perovskites remain crystalline during the oxygen evolution reaction (OER) in alkaline media, some highly active perovskites become amorphous. We studied the local structure changes of perovskites LaCoO3, Ba0.5Sr0.5Co0.8Fe0.2O3-δ, and SrCo0.8Fe0.2O3-δbefore and after OER by X-ray absorption spectroscopy. No change in either local structure or OER activity was observed for LaCoO3, while considerably enhanced OER activities and the conversion of the local structure from corner-sharing octahedra to edge-sharing octahedra were noted for Ba0.5Sr0.5Co0.8Fe0.2O3-δand SrCo0.8Fe0.2O3-δas a result of the OER. Possible processes responsible for the structural change and enhanced OER activities are discussed.

Published
2024
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31. Synthetic Alloys: Synthetic Crystals of Silver with Carbon: 3D Epitaxy of Carbon Nanostructures in the Silver Lattice (Adv. Funct. Mater. 30/2015)

Author

Salamanca‐Riba, Lourdes G., primary, Isaacs, Romaine A., additional, LeMieux, Melburne C., additional, Wan, Jiayu, additional, Gaskell, Karen, additional, Jiang, Yeping, additional, Wuttig, Manfred, additional, Mansour, Azzam N., additional, Rashkeev, Sergey N., additional, Kuklja, Maija M., additional, Zavalij, Peter Y., additional, Santiago, Jaime R., additional, and Hu, Liangbing, additional

Published
2015
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32. Synthetic Crystals of Silver with Carbon: 3D Epitaxy of Carbon Nanostructures in the Silver Lattice

Author

Salamanca-Riba, Lourdes G., primary, Isaacs, Romaine A., additional, LeMieux, Melburne C., additional, Wan, Jiayu, additional, Gaskell, Karen, additional, Jiang, Yeping, additional, Wuttig, Manfred, additional, Mansour, Azzam N., additional, Rashkeev, Sergey N., additional, Kuklja, Maija M., additional, Zavalij, Peter Y., additional, Santiago, Jaime R., additional, and Hu, Liangbing, additional

Published
2015
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33. Defective by design: vanadium-substituted iron oxide nanoarchitectures as cation-insertion hosts for electrochemical charge storage

Author

Chervin, Christopher N., primary, Ko, Jesse S., additional, Miller, Bryan W., additional, Dudek, Lisa, additional, Mansour, Azzam N., additional, Donakowski, Martin D., additional, Brintlinger, Todd, additional, Gogotsi, Pavel, additional, Chattopadhyay, Soma, additional, Shibata, Tomohiro, additional, Parker, Joseph F., additional, Hahn, Benjamin P., additional, Rolison, Debra R., additional, and Long, Jeffrey W., additional

Published
2015
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35. Trapping a Ru2O3Corundum-like Structure at Ultrathin, Disordered RuO2Nanoskins Expressed in 3D

Author

Donakowski, Martin D., Mansour, Azzam N., Pala, Irina R., Chervin, Christopher N., DeSario, Paul A., Long, Jeffrey W., and Rolison, Debra R.

Abstract

Protocols that express functional materials in a way that amplifies their surface-to-volume ratio offer a means to probe the structural ambiguity and surface-mediated reactivity of technologically important materials. We previously reported that three-dimensional (3D) ultraporous scaffolds, such as silica aerogels, silica fiber paper, and carbon nanofoam paper (CNF), provide a form factor that expresses energy-storing, catalytic ruthenium oxide (RuOx) as essentially all-surface—and a highly disordered one at that. To track the chemical state and solid-state structure of the 3D-expressed RuOxnanoskins as a function of thermal processing, we use X-ray near-edge structure (XANES), extended X-ray fine structure (EXAFS), and differential pair-distribution function (DPDF) analyses. We find that a Ru-centered ∼2.4 Å correlation present in the as-deposited oxide, also observed in PDF analysis of RuO2·nH2O but previously unassigned, fits the metastable corundum-like Ru2O3structure. This corundum-like feature diminishes in concentration with increasing treatment temperature (25–200 °C), commensurate with an increase in relative rutile RuO2content, electrical conductivity, and charge-storing capacitance of the oxide. Yet disorder persists beyond 8 Å, and a rutile nanocrystalline structure is not attained until >200 °C. The combination of synthetic amplification and total scattering analyses offers a viable approach to elucidate the structural ambiguity of practical, disordered nanomaterials.

Published
2018
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36. The Influence of Heat-Treatment Temperature on the Cation Distribution of LiNi[sub 0.5]Mn[sub 0.5]O[sub 2] and Its Rate Capability in Lithium Rechargeable Batteries

Author

Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Yabuuchi, Naoaki, Lu, Yi-chun, Chen, Shuo, Shao-Horn, Yang, Lu, Yi-Chun, Mansour, Azzam N., Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Yabuuchi, Naoaki, Lu, Yi-chun, Chen, Shuo, Shao-Horn, Yang, Lu, Yi-Chun, and Mansour, Azzam N.

Abstract

LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] samples were prepared from NiMnO[subscript 3] and Li[subscript 2]CO[subscript 3] in a range of temperatures from 900 to1050°C . Synchrotron X-ray diffraction analysis combined with X-ray absorption spectroscopy showed that LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2]segregated into one major Ni[superscript 2+]O -enriched phase and one minor Li[subscript 2]Mn[superscript 4+]O[subscript 3] -enriched phase, where the extent of segregation decreased with increasing synthesis temperature from 900 to1050°C . Scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy revealed that the segregated domains exist in individual particles. Although all of the LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] samples showed comparable specific capacity (∼200mAh/g) and capacity retention at low current densities, the rate capability of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] of 900°C is lower than that of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] of 1000°C . As X-ray photoelectron spectroscopy analysis showed that all of the LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] samples had comparable surface chemistry, the higher rate capability of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] of 1000°C can be attributed to reduced cation segregation of Ni[superscript 2+]O -enriched domains in the layered structure of the major phase, having potentially faster lithium diffusion than that of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] of 900°C ., United States. Dept. of Energy (Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Freedom CAR and Vehicle Technologies, DOE DE-AC03-76SF00098), Japan. Ministry of Education, Culture, Sports, Science and Technology (Nanotechnology Support Project Proposal no. 2009A1074/BL02B2 with the approval of Japan Synchrotron Radiation Research Institute (JASRI))

Published
2013

37. The Influence of Surface Chemistry on the Rate Capability of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] for Lithium Rechargeable Batteries

Author

Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Yabuuchi, Naoaki, Lu, Yi-Chun, Kawaguchi, Tadashi, Shao-Horn, Yang, Mansour, Azzam N., Massachusetts Institute of Technology. Department of Materials Science and Engineering, Massachusetts Institute of Technology. Department of Mechanical Engineering, Yabuuchi, Naoaki, Lu, Yi-Chun, Kawaguchi, Tadashi, Shao-Horn, Yang, and Mansour, Azzam N.

Abstract

Subsequent annealing at Formula enhances the rate capability of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2], delivering 180 mAh/g at 55[degrees]C and 8C rate compared to 50 mAh/g of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] quenched from 1000[degrees]C . Although Rietvled refinement analyses of X-ray diffraction (XRD) data showed that there were no significant changes in the lattice parameters and cation distributions of the layered structure before and after annealing, XRD and X-ray photoelectron spectroscopy revealed that annealing significantly reduced surface impurity phases such as lithium carbonate and Mn[superscript +3]-containing species. The influence of surface chemistry changes on the rate capability of LiNi[subscript 0.5]Mn[subscript 0.5]O[subscript 2] was discussed., United States. Dept. of Energy (Assistant Secretary for Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies of the DOE DE-AC03-76SF00098)

Published
2013

38. A New Type of Carbon Nanostructure Formed Within a Metal-Matrix

Author

MARYLAND UNIV COLLEGE PARK, Salamanca-Riba, Lourdes, Isaacs, Romaine, Mansour, Azzam N, Hall, Adam, Forrest, David R, LeMieux, Melburne C, Shugart, Jason, MARYLAND UNIV COLLEGE PARK, Salamanca-Riba, Lourdes, Isaacs, Romaine, Mansour, Azzam N, Hall, Adam, Forrest, David R, LeMieux, Melburne C, and Shugart, Jason

Abstract

Recent advances in nanomanufacturing have made it possible for large amounts ( 6 wt.%) of carbon to be incorporated as nanoscale carbon during a reaction process in molten aluminum, copper, silver, and other metals. These materials developed by Third Millennium Metals, LLC are called covetics. The carbon is highly stable despite its form not being predicted in phase diagrams, and remains dispersed after remelting and resolidification. The carbon incorporates into the metal matrix and has an effect on several of the properties of the material. We have performed a detailed investigation of the structure and composition of several covetics using a variety of microscopy and spectroscopy techniques and found that the carbon forms nanoparticles of 5-200 nm diameter that are embedded in the host matrix. EELS spectra obtained from these regions show characteristic shape of carbon nanotubes (CNT). Raman data obtained from these samples also show the G-mode and D-mode characteristic of CNT., Presented at Tech Connect World held in Santa Clara, CA on 18-12 June 2012. The original document contains color images.

Published
2012

41. Probing the Electrode-Electrolyte Interface in Cycled LiNi0.5Mn1.5O4 by XPS Using Mg and Synchrotron X-rays.

Author

Mansour, Azzam N., Kwabi, David G., Quinlan, Ronald A., Yi-Chun Lu, and Yang Shao-Horn

Subjects
X-ray photoelectron spectroscopy, ELECTRODES, ELECTROLYTES
Abstract

X-ray photoelectron spectroscopy (XPS) was used to investigate the surface chemistry of high voltage spinel, LiNi0.5Mn1.5O4 (LNMO) positive electrodes cycled 5 and 10 times in Li-cells with 1 M LiPF6 in (3:7) EC:DMC. The XPS spectra were collected using conventional Mg X-rays with energy of 1253.6 eV as well as synchrotron X-rays with energies of 2493.6 and 3498.4 eV in order to examine the depth distribution of various surface chemical species induced during cycling. The XPS spectra revealed a 5 - 10 nm surface layer of organic and LixPFyOz-type species formed as result of electrolyte decomposition, and a comparatively thinner layer composed of transition metal fluorides and LiF. These results suggest that electrolyte decomposition is a major contributor to parasitic reactions in LNMO battery electrochemistry. Limiting electrolyte decomposition with the use of solvents with wide electrochemical stability windows thus comprises a promising strategy for ensuring the practical feasibility of high voltage spinel materials in future Li-ion systems. [ABSTRACT FROM AUTHOR]

Published
2016
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