Na<sub>4‐α</sub>M<sub>2+α/2</sub>(P<sub>2</sub>O<sub>7</sub>)<sub>2</sub> (2/3 ≤ α ≤ 7/8, M = Fe, Fe<sub>0.5</sub>Mn<sub>0.5</sub>, Mn): A Promising Sodium Ion Cathode for Na‐ion Batteries
抄録
<jats:title>Abstract</jats:title><jats:p>A new polyanion‐based compound, Na<jats:sub>3.12</jats:sub>M<jats:sub>2.44</jats:sub>(P<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>)<jats:sub>2</jats:sub> (M = Fe, Fe<jats:sub>0.5</jats:sub>Mn<jats:sub>0.5</jats:sub>, Mn) is synthesized and examined as a cathode for Na ion batteries. Off‐stoichiometric synthesis induces the formation of a Na‐rich phase, Na<jats:sub>3.32</jats:sub>Fe<jats:sub>2.34</jats:sub>(P<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>)<jats:sub>2</jats:sub> ‐ a member of the solid solution series Na<jats:sub>4‐α</jats:sub>Fe<jats:sub>2+α/2</jats:sub>(P<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>)<jats:sub>2</jats:sub> (2/3 ≤ α ≤ 7/8) ‐ which delivers a reversible capacity of about 85 mA h g<jats:sup>−1</jats:sup> at ca. 3 V vs. Na/Na<jats:sup>+</jats:sup> and exhibits very stable cycle performance. Above all, it shows fast kinetics for Na ions, delivering an almost constant 72% reversible capacity at rates between C/10 and 10C without the necessity for nanosizing or carbon coating. We attribute this to the spacious channel size along the <jats:italic>a</jats:italic>‐axis, along with a single phase transformation upon de/sodiation.</jats:p>
収録刊行物
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- Advanced Energy Materials
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Advanced Energy Materials 3 (6), 770-776, 2013-02-18
Wiley
