First-Principles Investigation of Ti 2 CSO and Ti 2 CSSe Janus MXene Structures for Li and Mg Electrodes
First-Principles Investigation of Ti 2 CSO and Ti 2 CSSe Janus MXene Structures for Li and Mg Electrodes
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用于锂和镁电极的 Ti 2 CSO 和 Ti 2 CSSe Janus MXene 结构的第一性原理研究
DOI：
10.1021/acs.jpcc.1c00082
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Hu, Jianjun
中科院分区：
文献类型：
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作者：
Siriwardane, Edirisuriya M.;Hu, Jianjun
虽然锂电池电极在性能方面不断改进，但发现具有替代能量载体（如Mg）的新材料对于降低生产成本和提高能量密度非常重要。MXene是一种高度研究的材料，由于其优异的电子导电性和良好的机械和动力学稳定性，具有很好的能源应用前景。先前的实验研究表明，Janus MoSSe纳米片为电池电极提供了有前途的性能。然而，具有不同表面末端的MXene如何影响电化学性质和离子的扩散势垒还没有完全理解。在这里，我们通过研究Li和Mg电极的Ti 2 CSO和Ti 2 CSSe Janus MXenes来解决这个问题。我们的密度泛函理论为基础的，第一性原理计算表明，这两个单分子膜是热力学，机械和动力学稳定。我们计算出Li和Mg吸附的Ti 2CST（T = O和Se）MXene的平均电压分别约为0.95和0.2 V。最大电压为Ti 2CSTLixis约2 V和Ti 2CSTMgxis约0.45 V。Mg吸附的Ti 2CSO单层表现出最高的重量容量（524.54 mA h/g）相比，本文考虑的其他Janus MXenes。对于Ti 2CSSeLix，我们得到了更高的容量（230.45 mA h/g）和更低的扩散势垒（0.191 eV）比大多数的Li吸附的S-官能化的MXene。
While lithium battery electrodes are constantly being improved in terms of their performance, discovering new materials with alternative energy carriers such as Mg is important to lower the cost of production and to enhance the energy density. MXenes are a type of highly investigated materials with promising energy applications due to their excellent electronic conductivity and good mechanical and dynamical stability. Previous experimental studies showed that Janus MoSSe nanosheets provide promising performance for battery electrodes. However, it is not fully understood how MXenes with different surface terminations affect the electrochemical properties and the diffusion barriers of ions. Here, we address this problem by studying Ti2CSO and Ti2CSSe Janus MXenes for Li and Mg electrodes. Our density functional theory-based, first-principles calculations indicate that both monolayers are thermodynamically, mechanically, and dynamically stable. We calculated that the average voltages for Li- and Mg-adsorbed Ti2CST (T = O and Se) MXenes are approximately 0.95 and 0.2 V, respectively. The maximum voltage for Ti2CSTLixis about 2 V and that for Ti2CSTMgxis around 0.45 V. The Mg-adsorbed Ti2CSO monolayer exhibits the highest gravimetric capacity (524.54 mA h/g) compared to that of other Janus MXenes considered in this paper. For Ti2CSSeLix, we obtained a higher capacity (230.45 mA h/g) and a lower diffusion barrier (0.191 eV) than those of most of the Li-adsorbed S-functionalized MXenes.