First-Principles Study of the Voltage Profile and Mobility of Mg Intercalation in a Chromium Oxide Spinel,Chemistry of Materials

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First-Principles Study of the Voltage Profile and Mobility of Mg Intercalation in a Chromium Oxide Spinel
Chemistry of Materials ( IF 7.2 ) Pub Date : 2017-12-21 00:00:00 , DOI: 10.1021/acs.chemmater.7b04038
Tina Chen _{1,

2} , Gopalakrishnan Sai Gautam _{2,

3} , Wenxuan Huang _{2,

3} , Gerbrand Ceder _{1,

2}

Affiliation

The development of Mg batteries, which can potentially achieve higher energy densities than Li-ion systems, is in need of cathodes that can reversibly intercalate Mg²⁺ and exhibit a higher energy density than the state-of-the-art Chevrel and thio-spinel cathodes. Recent theoretical and experimental studies indicate that the oxide spinel family presents a set of promising Mg cathodes. Specifically, in this work, we investigate Mg intercalation into the spinel-Mg_xCr₂O₄ system. Using first-principles calculations in combination with a cluster expansion model and the nudged elastic band theory, we calculate the voltage curve for Mg insertion at room temperature and the activation barriers for Mg diffusion, respectively, at different Mg concentrations in the Cr₂O₄ structure. Our results identify a potential limitation to Mg intercalation in the form of stable Mg-vacancy orderings in the Cr₂O₄ lattice, which exhibit high migration barriers for Mg diffusion in addition to a steep voltage change. Additionally, we propose cation substitution as a potential mechanism that can be used to suppress the formation of the stable Mg-vacancy ordering, which can eventually enable the practical usage of Cr₂O₄ as a Mg-cathode.

中文翻译：

氧化铬尖晶石中Mg嵌入的电压分布和迁移率的第一性原理研究

Mg电池的开发可能比锂离子系统具有更高的能量密度，因此需要一种可逆地插入Mg ²⁺并显示出比最新的Chevrel和thio-sulfur更高的能量密度的阴极。尖晶石阴极。最近的理论和实验研究表明，氧化物尖晶石家族提供了一组有前途的Mg阴极。具体而言，在这项工作中，我们研究了镁在尖晶石中的嵌入-Mg _x Cr ₂ O ₄系统。结合簇扩展模型和微动弹性带理论，使用第一性原理计算，我们分别计算了在不同浓度的Cr ₂ O _4中，Mg在室温下的插入电压曲线和Mg扩散的激活势垒。结构体。我们的结果确定了以Cr ₂ O ₄晶格中稳定的Mg-空位有序形式对Mg插层的潜在限制，除了陡峭的电压变化外，这些Mg的扩散势垒也很高。另外，我们提出阳离子取代作为一种潜在的机制，可以用来抑制稳定的Mg-空位有序化的形成，最终可以使Cr的实际使用成为可能。₂ O ₄作为镁阴极。

更新日期：2017-12-21

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