Enabling Magnesium Anodes by Tuning the Electrode/Electrolyte Interfacial Structure
Enabling Magnesium Anodes by Tuning the Electrode/Electrolyte Interfacial Structure
复制标题
通过调整电极/电解质界面结构来实现镁阳极
DOI：
10.1021/acsami.1c10446
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发表时间：
2021
影响因子：
9.5
通讯作者：
Guo, Juchen
中科院分区：
文献类型：
--
作者：
Wen, Xiaoyu;Yu, Zhou;Zhao, Yifan;Zhang, Jian;Qiao, Rui;Cheng, Lei;Ban, Chunmei;Guo, Juchen
提出了一种新的沉积机理，以实现镁离子电池镁阳极的高度可逆电镀和剥离。已知电解质阴离子如双（三氟甲磺酰基）酰亚胺（TFSI-）的还原导致Mg表面钝化，导致Mg离子电池的电化学性能差。我们发现，在镁离子电解质中加入钠阳离子（Na+）可以从根本上改变镁阳极表面的界面化学和结构。分子动力学模拟表明，Na+阳离子有助于一个显着的人口在界面双层，使TFSI-阴离子被排除在邻近的Mg阳极的直接接口。因此，TFSI分解在很大程度上受到抑制，在Mg表面形成钝化层也是如此。这一机制得到了我们的电化学、显微镜和光谱分析的支持。与纯Mg（TFSI）2电解质相比，所得Mg沉积显示出光滑的表面形态和降低的过电位。
A new deposition mechanism is presented in this study to achieve highly reversible plating and stripping of magnesium (Mg) anodes for Mg-ion batteries. It is known that the reduction of electrolyte anions such as bis(trifluoromethanesulfonyl)imide (TFSI–) causes Mg surface passivation, resulting in poor electrochemical performance for Mg-ion batteries. We reveal that the addition of sodium cations (Na+) in Mg-ion electrolytes can fundamentally alter the interfacial chemistry and structure at the Mg anode surface. The molecular dynamics simulation suggests that Na+cations contribute to a significant population in the interfacial double layer so that TFSI–anions are excluded from the immediate interface adjacent to the Mg anode. As a result, the TFSI–decomposition is largely suppressed so does the formation of passivation layers at the Mg surface. This mechanism is supported by our electrochemical, microscopic, and spectroscopic analyses. The resultant Mg deposition demonstrates smooth surface morphology and lowered overpotential compared to the pure Mg(TFSI)2electrolyte.