Ion-Exchange Mechanism of Layered Transition-Metal Oxides: Case Study of LiNi0.5Mn0.5O2

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• 作者：Hyeokjo Gwon ; Sung-Wook Kim ; Young-Uk Park ; Jihyun Hong ; Gerbrand Ceder ; Seokwoo Jeon ; Kisuk Kang
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：August 4, 2014
• 年：2014
• 卷：53
• 期：15
• 页码：8083-8087
• 全文大小：338K
• ISSN：1520-510X

文摘

An ion-exchange process can be an effective route to synthesize new quasi-equilibrium phases with a desired crystal structure. Important layered-type battery materials, such as LiMnO₂ and LiNi_0.5Mn_0.5O₂, can be obtained through this method from a sodium-containing parent structure, and they often show electrochemical properties remarkably distinct from those of their solid-state synthesized equivalents. However, while ion exchange is generally believed to occur via a simple topotactic reaction, the detailed phase transformation mechanism during the process is not yet fully understood. For the case of layered LiNi_0.5Mn_0.5O₂, we show through ex situ X-ray diffraction (XRD) that the ion-exchange process consists of several sequential phase transformations. By a study of the intermediate phase, it is shown that the residual sodium ions in the final structure may greatly affect the electrochemical (de)lithiation mechanism.