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20. From high‐pressure β‐V2O5 to κ‐NaxV2O5 (x = 0.4 − 0.55): A structural, chemical, and kinetic insight into a sodiated phase with a large interlayer space

Author

Córdoba, Rafael, Goclon, Jakub, Sarapulova, Angelina, Fu, Qiang, Maibach, Julia, Dsoke, Sonia, Fauth, François, Kuhn, Alois, and García‐Alvarado, Flaviano

Abstract

Vanadium pentoxide polymorphs are attracting much interest due to their remarkable electrochemical performance as positive electrodes for rechargeable metal‐ion batteries. High‐pressure β‐V2O5 is an interesting positive electrode material for Na‐ion batteries able to intercalate 1 Na+/formula unit delivering a capacity of 147 mAh g−1. The sodium intercalation of 0.4 Na+ has been described in the literature as a two‐phase domain involving an important structural rearrangement yielding NaxV2O5, but details about the structural changes upon sodium intercalation and structure of intercalated Na0.4V2O5 have not been elucidated so far. In this work, we performed operando synchrotron X‐ray diffraction measurements on sodium batteries on discharge. A full crystal structure determination for such phase, which we have called κ‐Na0.4V2O5, was carried out for the first time directly from operando measurements in monoclinic space group C2/m. Structural analysis was completed with bond valence sum calculations revealing the sites of intercalated sodium in κ‐NaxV2O5 and the structure was further optimized by means of density functional theory calculations. Operando X‐ray absorption spectroscopy and ex situ X‐ray photoelectron spectroscopy allowed to unveil the redox changes upon the phase transformation from β‐V2O5 into κ‐NaxV2O5, providing information about the reduction of vanadium from V5+ to V4+. The phase transformation also produced enhanced charge transfer and sodium diffusion processes, as deduced from both impedance and kinetic study. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Reduction of Grain Boundary Resistance of La0.5Li0.5TiO3 by the Addition of Organic Polymers

Author

Boyano, Iker. and García Alvarado, Flaviano.

Subjects
Energía eléctrica, Solid ceramicpolymer composite electrolyte, Grain boundary resistance, Lithium ion conductivity, Batería de ion de litio, Lithium lanthanum titanium oxide (LLTO)
Abstract

Artículo en colaboración con: Aroa R. Mainar, J. Alberto Blázquez, Andriy Kvasha, Miguel Bengoechea, Iratxe de Meatza, Susana García-Martín, Alejandro Varez, Jesús Sanz and Flaviano García-Alvarado En: Nanomaterials ISSN: 2079-4991 v. 11, n. 61, 2021, 12 pp The organic solvents that are widely used as electrolytes in lithium ion batteries present safety challenges due to their volatile and flammable nature. The replacement of liquid organic electrolytes by non-volatile and intrinsically safe ceramic solid electrolytes is an effective approach to address the safety issue. However, the high total resistance (bulk and grain boundary) of such compounds, especially at low temperatures, makes those solid electrolyte systems unpractical for many applications where high power and low temperature performance are required. The addition of small quantities of a polymer is an efficient and low cost approach to reduce the grain boundary resistance of inorganic solid electrolytes. Therefore, in this work, we study the ionic conductivity of different composites based on non-sintered lithium lanthanum titanium oxide (La0.5Li0.5TiO3) as inorganic ceramic material and organic polymers with different characteristics, added in low percentage (

Published
2021

27. Reduction of Grain Boundary Resistance of La0.5Li0.5TiO3 by the Addition of Organic Polymers

Author

Ministerio de Ciencia y Tecnología (España), European Commission, Agencia Estatal de Investigación (España), Boyano, Iker, Mainar, Aroa R., Blázquez, J. Alberto, Kvasha, Andriy, Bengoechea, Miguel, de Meatza, Iratxe, García-Martín, Susana, Várez, Álvarez Alejandro, Sanz Perucha, Jesús, García-Alvarado, Flaviano, Ministerio de Ciencia y Tecnología (España), European Commission, Agencia Estatal de Investigación (España), Boyano, Iker, Mainar, Aroa R., Blázquez, J. Alberto, Kvasha, Andriy, Bengoechea, Miguel, de Meatza, Iratxe, García-Martín, Susana, Várez, Álvarez Alejandro, Sanz Perucha, Jesús, and García-Alvarado, Flaviano

Abstract

The organic solvents that are widely used as electrolytes in lithium ion batteries present safety challenges due to their volatile and flammable nature. The replacement of liquid organic electrolytes by non-volatile and intrinsically safe ceramic solid electrolytes is an effective approach to address the safety issue. However, the high total resistance (bulk and grain boundary) of such compounds, especially at low temperatures, makes those solid electrolyte systems unpractical for many applications where high power and low temperature performance are required. The addition of small quantities of a polymer is an efficient and low cost approach to reduce the grain boundary resistance of inorganic solid electrolytes. Therefore, in this work, we study the ionic conductivity of different composites based on non-sintered lithium lanthanum titanium oxide (La0.5Li0.5TiO3) as inorganic ceramic material and organic polymers with different characteristics, added in low percentage (<15 wt.%). The proposed cheap composite solid electrolytes double the ionic conductivity of the less cost-effective sintered La0.5Li0.5TiO3.

Published
2020

35. Defect chemistry, electrical properties and evaluation of new oxides Sr2CoNb1-xTixO6-δ (0?x?1) as cathode materials for Solid Oxide Fuel Cells / M. Teresa Azcondo ... [et al.]

Author

García Alvarado, Flaviano, coaut., Pérez Flores, Juan Carlos, coaut., Amador Elizondo, Ulises, coaut., Azcondo, Ma Teresa, coaut., and Yuste, Mercedes, coaut.

Subjects
Cobalto, Almacenamiento eléctrico, Conductividad
Abstract

Artículo en colaboración con: Mercedes Yuste, Juan Carlos Pérez-Flores, Daniel Muñoz-Gil, Susana García-Martín, Alvaro Muñoz-Noval, Inés Puente Orench Flaviano García-Alvarado y Ulises Amador En: ChemSusChem ISSN: 1864-564x n. 10, 2017, p. 2978-2989 Post-print

Published
2018

38. Lithium Intercalation Mechanism and Critical Role of Structural Water in Layered H2V3O8High-Capacity Cathode Material for Lithium-Ion Batteries

Author

Kuhn, Alois, Pérez-Flores, Juan Carlos, Prado-Gonjal, Jesús, Morán, Emilio, Hoelzel, Markus, Díez-Gómez, Virginia, Sobrados, Isabel, Sanz, Jesús, and García-Alvarado, Flaviano

Abstract

H2V3O8(HVO) is a promising high-capacity cathode material for lithium-ion batteries (LIBs). It allows reversible two-electron transfer during electrochemical lithium cycling processes, yielding a very attractive theoretical capacity of 378 mAh g–1. While an abundant number of research works exclusively proved the outstanding electrochemical lithium storage properties of H2V3O8, structural changes during the intercalation process have not been scrutinized, and the crystallographic positions occupied by the guest species have not been revealed yet. However, an in-depth understanding of structural changes of cathode materials is essential for developing new materials and improving current materials. Aimed at providing insights into the storage behavior of HVO, in this work, we employed a combination of high-resolution synchrotron X-ray and neutron diffraction to accurately describe the crystal structures of both pristine and lithiated H2V3O8. In HVO, hydrogen is located on one single-crystallographic site in a waterlike arrangement, through which bent asymmetric hydrogen bonds across adjacent V3O82–chains are established. The role played by water in network stabilization was further examined by density functional theory (DFT) calculations. Easy hydrogen-bonding switch of structural water upon lithium intercalation not only allows better accommodation of intercalated lithium ions but also enhances Li-ion mobility in the crystal host, as evidenced by magic-angle spinning (MAS) NMR spectroscopy. Facile conduction pathways for Li ions in the structure are deduced from bond valence sum difference mapping. The hydrogen bonds mitigate the volume expansion/contraction of vanadium layers during Li intercalation/deintercalation, resulting in improved long-term structural stability, explaining the excellent performance in rate capability and cycle life reported for this high-energy cathode in LIBs. This study suggests that many hydrated materials can be good candidates for electrode materials in not only implemented Li technology but also emerging rechargeable batteries.

Published
2022
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40. The effect of ceramic synthesis conditions on the electrochemical properties of Li2Ti30 / P. Díaz- Carrasco ... [et al.]

Author

Amador, Ulises, coaut., Pérez Flores, Juan Carlos, coaut., Díaz Carrasco, P., coaut., and García Alvarado, Flaviano, coaut.

Subjects
Energía eléctrica - Almacenamiento
Abstract

Artículo en colaboración con: P. C. Miscow Ferreira, O. Dolotko, J. C. Pérez? Fiores, U. Amador, A. Kuhn and F. García-Alvarado En: Journal of Materials Science. ISSN. e-1573-4803 . n. 51, (2016), 4520-4529 Preprint

Published
2017

44. The A-cation Deficient Perovskite Series La2-xCoTiO6-δ (0≤x≤0.20): new Potential Cathodes for Solid Oxide Fuel Cells / Alejandro Gómez-Pérez... [et al.]

Author

Amador, Ulises, coaut., Gómez Pérez, Alejandro, coaut., and García Alvarado, Flaviano, coaut.

Subjects
Generación de energía eléctrica
Abstract

Artículo en colaboración con: M. Teresa Azcondoa, Mercedes Yustea, Juan Carlos Perez-Floresa, Nikolaos Bonanosb, Florence Porcherc, Alvaro Munoz-Novald, Markus Hoelzele, Flaviano Garcia-Alvarado and Ulises Amador En: Journal of Materials Chemistry A. ISSN. 2050-7488. v. 4, (2016), págs. 3386-3397 Pre-print del autor

Published
2016

45. A-site order in rhombohedral perovskite-like oxides La2-xSrxCoTiO6 (0.6 ≤ x ≤ 1.0)

Author

Amador, Ulises., García Alvarado, Flaviano., and Gómez Pérez, Alejandro.

Subjects
Cobaltite, Difracción, Phase transitions, Perovskites, Synchrotron X-ray diffraction, AMPLIMODES, Neutron diffraction
Abstract

Artículo en colaboración con : Clemens Ritter, Khalid Boulahya, Alvaro Muñoz-Noval, Flaviano García-Alvarado and Ulises Amador En: Journal of Applied Crystallography. ISSN. 1600-5767. 2016, (2016) 49, 31-39. The evolution of the room-temperature structure of the oxide series La2xSrxCoTiO6 (0.6 x 1.0) was studied as a function of the Sr content using different diffraction techniques and applying the symmetry-adapted modes formalism (AMPLIMODES). The title compounds adopt perovskite-like structures of rhombohedral symmetry with an octahedral tilting scheme (aaa) with either space group R3c or R32. The latter symmetry is observed in those cases (for x ’ 0.6) where additional rock-salt-like ordering of La and Sr is produced in the perovskite A sites. Two composition-driven phase transitions are observed in the whole series La2xSrxCoTiO6 (0.0 x 1.0). Using the concept of internal pressure, the effect of doping with Sr on the structure can be properly discussed. Both phase transitions seem to be of first order since they can be associated with discontinuities either in the entropy or in the structure. The first transition (P21/n ! Pnma) occurs as the B cations become totally disordered. Along the whole compositional range the modes responsible for the out-of-phase tilting of BO6 octahedra remain active, but those associated with the in-phase octahedral tilting vanish for x 0.6, this being associated with the second transition (Pnma ! R3c). Finally, for x = 1.0 the three pseudo-cubic cell parameters become very similar, pointing to a transition to a cubic structure which could be obtained by applying pressure or raising the temperature.

Published
2016

47. The effect of ceramic synthesis conditions on the electrochemical properties of Li2Ti30

Author

Amador, Ulises., Pérez Flores, Juan Carlos., Díaz Carrasco, P., and García Alvarado, Flaviano.

Subjects
Energía eléctrica - Almacenamiento
Abstract

Artículo en colaboración con: P. C. Miscow Ferreira, O. Dolotko, J. C. Pérez? Fiores, U. Amador, A. Kuhn and F. García-Alvarado En: Journal of Materials Science. ISSN. e-1573-4803 . n. 51, (2016), 4520-4529 Preprint

Published
2016

48. Defect Chemistry, Electrical Properties, and Evaluation of New Oxides Sr2CoNb1−xTixO6−δ (0≤x≤1) as Cathode Materials for Solid Oxide Fuel Cells

Author

Azcondo, María Teresa, primary, Yuste, Mercedes, additional, Pérez‐Flores, Juan Carlos, additional, Muñoz‐Gil, Daniel, additional, García‐Martín, Susana, additional, Muñoz‐Noval, Alvaro, additional, Orench, Inés Puente, additional, García‐Alvarado, Flaviano, additional, and Amador, Ulises, additional

Published
2017
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50. Structure evolution with Sr content of the perovskite-like materials La2-xSrxCoTiO6 (0 <= x <= 0.5) / J.C. Pérez-Flores ... [et al.]

Author

García Alvarado, Flaviano, coaut., Pérez Flores, Juan Carlos, coaut., and Amador, Ulises, coaut.

Subjects
Energía eléctrica - Almacenamiento, Pilas de combustible
Abstract

Artículo en colaboración con : Gómez-Pérez, A.; Ritter, C.; Boulahya, K.; Castro, G. R.; Garcia-Alvarado, F.; Amador, U. En: Journal of Applied Crystallography. ESSN. 1600-5767. n. 47, (2014) : 745-754

Published
2015

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