通过使用操作PDF和NMR光谱学,全面了解混合离子FeOF电极的结构和化学变化
Kamila M Wiaderek1, Olaf J Borkiewicz, Elizabeth Castillo-Martínez
1X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Journal of the American Chemical Society
|February 26, 2013
概括
高性能铁氧化物电极揭示了一个可逆的电化学反应机制. 循环形成一个纳米复合材料结构,铁在富含的环境中优先反应.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 固态化学 固态化学
背景情况:
- 铁氧化物是用于储能应用的有希望的高性能电极材料.
- 了解它们的电化学反应机制对于优化性能和稳定性至关重要.
研究的目的:
- 阐明铁氧化物电极的详细电化学反应机制.
- 为了研究电极材料在循环过程中的结构演变.
主要方法:
- 操作的X射线对分布函数 (PDF) 分析.
- 核磁共振 (Li NMR) 光谱学.
- 债券价值总和 (BVS) 分析.
主要成果:
- 电化学反应是可逆的,充电后完全恢复放电能力.
- 电极循环的结果是一个纳米复合材料结构,包括无形的鲁和纳米级岩盐相.
- 发生离子分离,形成富含F的鲁和富含O的岩盐相,铁在富含F的环境中优先反应.
结论:
- 循环诱导的纳米复合材料结构决定了铁氧化电极的电化学行为.
- 富含F和O相的顺序反应,由铁在富含的环境中的偏好反应驱动,支配着整体机制.
相关概念视频
Electrogravimetric Analysis: Overview
Electrogravimetric analysis measures the weight of an analyte deposited electrolytically onto a suitable working electrode. This method involves applying a potential to a pre-weighed electrode submerged in a solution, which results in the desired substance being deposited through reduction at the cathode or oxidation at the anode. The electrode's weight is recorded after deposition, and the difference in weight gives the analyte's weight in the solution.
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π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
Electrochemistry: Overview
Electrochemistry is the branch of chemistry that studies the relationship between electrical quantities and chemical reactions, particularly oxidation and reduction. Oxidation is the loss of electrons from a substance, whereas reduction refers to the gain of electrons. A substance with a strong electron affinity is called an oxidizing agent (oxidant), and a reducing agent (reductant) is a species that donates electrons. Oxidation and reduction processes are pivotal to electrochemical reactions,...
Ladder Diagrams: Redox Equilibria
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
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Electrodeposition
Electrodeposition is a technique used to separate an analyte from interferents by electrochemical processes. Here, the analyte is a metal ion that can be deposited on an electrode immersed in the sample solution. The electrochemical setup consists of an anode and a cathode. When an electric current is applied to the setup, oxidation occurs at the anode. At the cathode, which consists of a large metal surface, metal ions undergo reduction and deposit onto the surface.
Electrodeposition can...
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