尖晶石
Crystal(编程语言)
相变
化学物理
材料科学
相(物质)
水溶液
分子
结晶学
晶体结构
过渡金属
化学
热力学
物理化学
冶金
催化作用
计算机科学
程序设计语言
有机化学
物理
生物化学
作者
Eunjeong Yang,Heejin Kim,Sangryun Kim,In Kim,Jaehoon Kim,Hyunjun Ji,Jang Wook Choi,Yousung Jung
出处
期刊:Chemical Science
[The Royal Society of Chemistry]
日期:2017-10-24
卷期号:9 (2): 433-438
被引量:33
摘要
It is well known that many layered transition metal oxides can transform into a spinel structure upon repeated battery cycling, but a phase transition in the opposite direction is rare. Recently, the transformation from spinel Mn3O4 to layered MnO2 was observed during the operation of a Mg battery in aqueous conditions, resulting in high performance Mg batteries. We hereby use ab initio calculations to unveil the mechanism by which crystal water plays a critical role in this unique transformation. Once inserted into the spinel form, a water molecule donates an electron, offering a key structural and thermodynamic driving force to initiate the transformation process. These crystal water molecules then get favorably clustered into a planar form in the layered structure and act as a stabilizing agent for birnessite. Kinetically, the inserted crystal water dramatically promotes the necessary rearrangement of Mn during the transition by lowering the activation barrier by >2 eV. The present structural, thermodynamic and kinetic understanding of the crystal water-driven phase transition provides novel insights to further the design of related low dimensional hydrated materials for multi-valent cathodes.
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