From Trigonal to Cubic LiVO2: A High-Energy Phase Transition Towards Disordered Rock Salt Materials

Johann Chable*, Christian Baur, Jinhyun Chang, Sebastian Wenzel, Juan Maria García Lastra, Tejs Vegge

*Corresponding author for this work

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Abstract

Facile and reversible insertion and extraction of Li+ was recently demonstrated to be possible with a new cation-disordered rock salt (DRS) LiVO2 compound (Space Group (SG): Fm3 ̅m). Further structural analyses describing the links between the well-known layered trigonal structure of LiVO2 (space group:R3 ̅m) and DRS LiVO2 synthesized by mechanical ball milling are presented. Optimized Rietveld refinements of the X-ray diffraction patterns confirm the formation of LiVO2 in disordered rock salt phase. We observed the phase transition from the trigonal to cubic structure and the evolution of cell parameters during the ball-milling process using ex situ X-ray diffraction. The reverse phase transition from cubic to trigonal structure is achieved via thermal treatment, which was confirmed via differential scanning calorimetry and in situ X-ray diffraction experiments. The phase transition to trigonal structure suggests the metastability of the cubic structure. An exhaustive computational analysis based on a cluster expansion model trained by density functional theory calculations is conducted to confirm the metastability. The presented methods and results show that different (meta-)stable phases can be achieved depending on the synthesis method, which is an important aspect to consider in investigating the properties of the new DRS cathode materials for Li-ion batteries.
Original languageEnglish
JournalJournal of Physical Chemistry C
Volume124
Issue number3
Pages (from-to)2229-2237
ISSN1932-7447
DOIs
Publication statusPublished - 2020

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