Sodium and Manganese Stoichiometry of P2-Type Na2/3 MnO2.
Angew Chem Int Ed Engl
; 55(41): 12760-3, 2016 10 04.
Article
em En
| MEDLINE
| ID: mdl-27630078
ABSTRACT
To realize a reversible solid-state Mn(III/IV) redox couple in layered oxides, co-operative Jahn-Teller distortion (CJTD) of six-coordinate Mn(III) (t2g (3) -eg (1) ) is a key factor in terms of structural and physical properties. We develop a single-phase synthesis route for two polymorphs, namely distorted and undistorted P2-type Na2/3 MnO2 having different Mn stoichiometry, and investigate how the structural and stoichiometric difference influences electrochemical reaction. The distorted Na2/3 MnO2 delivers 216â
mAh g(-1) as a 3â
V class positive electrode, reaching 590â
Wh (kg oxide)(-1) with excellent cycle stability in a non-aqueous Na cell and demonstrates better electrochemical behavior compared to undistorted Na2/3 MnO2 . Furthermore, reversible phase transitions correlated with CJTD are found upon (de)sodiation for distorted Na2/3 MnO2 , providing a new insight into utilization of the Mn(III/IV) redox couple for positive electrodes of Na-ion batteries.
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MEDLINE
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En
Ano de publicação:
2016
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Article