Department of Materials Sciences and Engineering, University of California, Berkeley, California, 94720, USA.
Materials Science Division, Lawrence Berkeley National Lab, Berkeley, California, 94720, USA.
Sci Rep. 2017 Feb 10;7:42527. doi: 10.1038/srep42527.
We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. We found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems.
我们采用多模态方法研究了 Ti 和 Au 电极上的 Mg 阴极电化学沉积，通过原位使用液体池透射电子显微镜（TEM）、扫描透射 X 射线显微镜（STXM）和 X 射线吸收光谱（XAS）检查样品区域。我们合成了氯化镁铝复合物并将其用作电解质，在原位充放电循环过程中观察到不可逆特征。在充电过程中，在电极上沉积了均匀的 Mg 膜，这与 Mg 离子电池中 Mg 沉积的固有非枝晶性质一致。在随后的放电过程中，Mg 薄膜不溶解。我们通过原位 STXM 和 XAS 发现，这种 Mg 薄膜是六配位的 Mg 化合物。该研究为 Mg 离子电池的不可逆性问题和失效机制提供了深入的了解。此外，我们的方法提供了一种新颖的通用方法，可以在无需进一步样品处理的情况下了解原位电池化学，这可以保留电池材料或电沉积材料的原始性质。这种多模态原位成像和光谱学提供了许多机会来解决跨越长度和时间尺度多个数量级的复杂问题，可应用于广泛的储能系统。
