# Phase Transformation Behavior and Stability of LiNiO$_{2}$ Cathode Material for Li-Ion Batteries Obtained from In Situ Gas Analysis and Operando X-Ray Diffraction

de Biasi, Lea; Schiele, Alexander; Roca‐Ayats, Maria; Garcia, Grecia; Brezesinski, Torsten; Hartmann, Pascal; Janek, Jürgen

##### Abstract:
Ni-rich layered oxide cathode materials, in particular the end member LiNiO$_{2}$, suffer from drawbacks such as high surface reactivity and severe structural changes during de-/lithiation, leading to accelerated degradation and limiting practical implementation of these otherwise highly promising electrode materials in Li-ion batteries. Among all known phase transformations occurring in LiNiO$_{2}$, the one from the H2 phase to the H3 phase at high state of charge is believed to have the most detrimental impact on the material’s stability. In this work, the multistep phase transformation process and associated effects are analyzed by galvanostatic cycling, operando X-ray diffraction, and in situ pressure and gas analysis. The combined results provide thorough insights into the structural changes and how they affect the stability of LiNiO$_{2}$. During the H2–H3 transformation, the most significant change occurs in the c-lattice parameter, resulting in large mechanical stress in LiNiO$_{2}$. As for electrochemical stability, it suffers strongly in the H3 region. Oxygen evolution is observed not only during charge but also during discharge and found to be correlated with the presence of the H2 and H3 phases. ... mehr

 Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT) Publikationstyp Zeitschriftenaufsatz Publikationsjahr 2019 Sprache Englisch Identifikator ISSN: 1864-5631, 1864-564X KITopen-ID: 1000094300 HGF-Programm 37.01.01 (POF III, LK 01) Fundamentals and Materials Erschienen in ChemSusChem Verlag Wiley-VCH Verlag Band 12 Heft 10 Seiten 2240-2250 Vorab online veröffentlicht am 04.04.2019 Nachgewiesen in DimensionsWeb of ScienceScopus
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