Crystal Chemistry and Electrochemistry of Li x Mn 1.5Ni 0.5O 4Solid Solution Cathode Materials

Crystal Chemistry and Electrochemistry of Li x Mn 1.5Ni 0.5O 4Solid Solution Cathode Materials

TitleCrystal Chemistry and Electrochemistry of Li x Mn 1.5Ni 0.5O 4Solid Solution Cathode Materials
Publication TypeJournal Article
Year of Publication2017
AuthorsWang Hay Kan, Saravanan Kuppan, Lei Cheng, Marca M Doeff, Jagjit Nanda, Ashfia Huq, Guoying Chen
JournalChemistry of Materials
Volume29
Issue16
Pagination6818 - 6828
Date Published07/2017
ISSN0897-4756
Abstract

For ordered high-voltage spinel LiMn1.5Ni0.5O4 (LMNO) with the P4321 symmetry, the two consecutive two-phase transformations at ∼4.7 V (vs Li+/Li), involving three cubic phases of LMNO, Li0.5Mn1.5Ni0.5O4 (L0.5MNO), and Mn1.5Ni0.5O4 (MNO), have been well-established. Such a mechanism is traditionally associated with poor kinetics due to the slow movement of the phase boundaries and the large mechanical strain resulting from the volume changes among the phases, yet ordered LMNO has been shown to have excellent rate capability. In this study, we show the ability of the phases to dissolve into each other and determine their solubility limit. We characterized the properties of the formed solid solutions and investigated the role of non-equilibrium single-phase redox processes during the charge and discharge of LMNO. By using an array of advanced analytical techniques, such as soft and hard X-ray spectroscopy, transmission X-ray microscopy, and neutron/X-ray diffraction, as well as bond valence sum analysis, the present study examines the metastable nature of solid-solution phases and provides new insights in enabling cathode materials that are thermodynamically unstable.

DOI10.1021/acs.chemmater.7b0189810.1021/acs.chemmater.7b01898.s001
Short TitleChem. Mater.
Refereed DesignationRefereed