Department of Applied Chemistry, Tokyo Denki University
Department of Applied Chemistry, Tokyo Denki University
Department of Applied Chemistry, Tokyo Denki University / Elements Strategy Initiative for Catalysts and Batteries, Kyoto University
Technology Department, Electronic Materials Group, JX Nippon Mining & Metals Corporation
Department of Applied Chemistry, Tokyo Denki University / Elements Strategy Initiative for Catalysts and Batteries, Kyoto University / Department of Chemistry and Life Science, Yokohama National University
抄録
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.
Metastable and nanosize cation-disordered rocksalt-type oxides: revisit of stoichiometric LiMnO2 and NaMnO2
2018 JMCA LiMnO2 NaMnO2.pdf
(5.08MB)
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