Issue 28, 2018

Metastable and nanosize cation-disordered rocksalt-type oxides: revisit of stoichiometric LiMnO2 and NaMnO2

Abstract

Stoichiometric LiMnO2 and NaMnO2 with a cation-disordered rocksalt-type structure as metastable polymorphs were successfully prepared by mechanical milling. Although cation-disordered rocksalt phases with a stoichiometric composition (Li : Mn molar ratio = 1 : 1) are expected to be electrochemically less active, both samples show superior performance as electrode materials when compared with thermodynamically stable layered phases in Li/Na cells. Both metastable samples deliver large reversible capacities, which correspond to >80% of their theoretical capacities, with relatively small polarization on the basis of reversible Mn3+/Mn4+ redox. Moreover, for rocksalt LiMnO2, the phase transition into a spinel phase is effectively suppressed compared with a thermodynamically stable phase. The electrode reversibility of NaMnO2 is also drastically improved by the use of the metastable phase with good capacity retention. Metastable phases with unique nanostructures open a new path for the design of advanced electrode materials with high energy density, and thus a broad impact is anticipated for rechargeable Li/Na battery applications.

Graphical abstract: Metastable and nanosize cation-disordered rocksalt-type oxides: revisit of stoichiometric LiMnO2 and NaMnO2

Supplementary files

Article information

Article type
Paper
Submitted
21 apr 2018
Accepted
22 iyn 2018
First published
22 iyn 2018

J. Mater. Chem. A, 2018,6, 13943-13951

Metastable and nanosize cation-disordered rocksalt-type oxides: revisit of stoichiometric LiMnO2 and NaMnO2

T. Sato, K. Sato, W. Zhao, Y. Kajiya and N. Yabuuchi, J. Mater. Chem. A, 2018, 6, 13943 DOI: 10.1039/C8TA03667E

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