High Voltage Mg-Doped Na0.67Ni0.3-xMgxMn0.7O2 (x=0.05, 0.1) Na-Ion Cathodes with Enhanced Stability and Rate Capability
High Voltage Mg-Doped Na0.67Ni0.3-xMgxMn0.7O2 (x=0.05, 0.1) Na-Ion Cathodes with Enhanced Stability and Rate Capability
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DOI：
10.1021/acs.chemmater.6b01935
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发表时间：
2016-07-26
影响因子：
8.6
通讯作者：
Bruce, Peter G.
中科院分区：
文献类型：
--
作者：
Singh, Gurpreet;Tapia-Ruiz, Nuria;Bruce, Peter G.
通过简便的固相方法制备了镁取代的 P2 结构 Na0.67Ni0.3Mn0.7O2 材料，并将其作为钠离子电池的阴极进行了研究。本文描述的镁掺杂材料通过 X 射线衍射 (XRD)、Na-23 固态核磁共振 (SS-NMR) 和扫描电子显微镜 (SEM) 进行表征。在室温下，在半电池与钠金属中测试了样品的电化学性能。镁掺杂材料的工作平均电压约为 100V。 3.3 V 与 Na/Na+ 相比，提供类似于 120 mAh g(-1) 的比容量，并且在长达 50 次循环后仍保持稳定。 Mg掺杂通过在充电期间（在Na去除期间）稳定可逆OP4相来抑制在未掺杂组合物中观察到的众所周知的P2-O2相变。 GITT 测量表明，Na 离子迁移率相对于母体 P2-Na0.67Ni0.3Mn0.7O2 材料提高了 2 个数量级。快速的Na离子迁移率可能是倍率性能增强的原因。
Magnesium substituted P2-structure Na0.67Ni0.3Mn0.7O2 materials have been prepared by a facile solid-state method and investigated as cathodes in sodium-ion batteries. The Mg-doped materials described here were characterized by Xray diffraction (XRD), Na-23 solid-state nuclear magnetic resonance (SS-NMR), and scanning electron microscopy (SEM). The electrochemical performance of the samples was tested in half cells vs Na metal at room temperature. The Mg-doped materials operate at a high average voltage of ca. 3.3 V vs Na/Na+ delivering specific capacities of similar to 120 mAh g(-1), which remain stable up to 50 cycles. Mg doping suppresses the well-known P2-O2 phase transition observed in the undoped composition by stabilizing the reversible OP4 phase during charging (during Na removal). GITT measurements showed that the Na-ion mobility is improved by 2 orders of magnitude with respect to the parent P2-Na0.67Ni0.3Mn0.7O2 material. The fast Na-ion mobility may be the cause of the enhanced rate performance.