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Charge Transfer-Induced Lattice Collapse in Ni-Rich NCM Cathode Materials during Delithiation

Kondrakov, Aleksandr Olegovič; Geßwein, Holger; Galdina, Kristina; De Biasi, Lea; Meded, Velimir; Filatova, Elena O.; Schumacher, Gerhard; Wenzel, Wolfgang; Hartmann,Pascal; Brezesinski, Torsten; Janek, Jürgen

Abstract (englisch):
Ni-rich LiNixCoyMnzO2 (NCM) cathode materials have great potential for application in next-generation lithium-ion batteries owing to their high specific capacity. However, they are subjected to severe structural changes upon (de)lithiation, which adversely affects the cycling stability. Herein, we investigate changes in crystal and electronic structure of NCM811 (80% Ni) at high states of charge by a combination of operando X-ray diffraction (XRD), operando hard X-ray absorption spectroscopy (hXAS), ex situ soft X-ray absorption spectroscopy (sXAS), and density functional theory (DFT) calculations, and correlate the results with data from galvanostatic cycling in coin cells. XRD reveals a large decrease in unit cell volume from 101.38(1) Å3 to 94.26(2) Å3 due to collapse of the interlayer spacing when x(Li) < 0.5 (decrease in c-axis from 14.469(1) Å at x(Li) = 0.6 to 13.732(2) Å at x(Li) = 0.25). hXAS shows that the shrinkage of the transition metal-oxygen layer mainly originates from nickel oxidation. sXAS, together with DFT-based Bader charge analysis, indicates that the shrinkage of the interlayer, which is occupied by lithium, is induced by charge transfer between O 2p and partially filled Ni eg orbitals (resulting in decrease of oxygen-oxygen repulsion). ... mehr

DOI: 10.1021/acs.jpcc.7b06598
Zitationen: 108
Zitationen: 115
Zugehörige Institution(en) am KIT Fakultät für Maschinenbau (MACH)
Institut für Angewandte Materialien - Keramische Werkstoffe und Technologien (IAM-KWT)
Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 11.10.2017
Sprache Englisch
Identifikator ISSN: 1932-7447, 1932-7455
KITopen-ID: 1000076121
HGF-Programm 37.01.01 (POF III, LK 01) Fundamentals and Materials
Erschienen in The journal of physical chemistry <Washington, DC> / C
Verlag American Chemical Society (ACS)
Band 121
Heft 44
Seiten 24381-24388
Nachgewiesen in Dimensions
Web of Science
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