Department of Materials Science and Engineering, Korea University , Seoul 02841, South Korea.
Process Technology Group, Process Center, R&D Division, SK Hynix , Icheon 17336, South Korea.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):560-568. doi: 10.1021/acsami.7b14680. Epub 2017 Dec 20.
Sodiation was performed on crystalline Sn cylinders using an in situ electron microscope to evaluate the rate performance of the Sn anode by directly measuring the sodiation rate. We observed that the sodiation rate of the Sn anode is more than 2 orders of magnitude higher than the lithiation rate of the Si anode under the same conditions. This unprecedented rate displayed by the Na-Sn system is attributed to the bond characteristics and crystalline-to-amorphous transformation of the Sn crystal at the thin interface of the Na-Sn diffusion couple. Here, using atomic simulations, we explain how and why the Sn anode exhibits this high rate performance by resolving the diffusion process of Na ions in the Na-Sn interfacial region and the electron structure of the crystalline Sn. This work provides a useful insight into the use of Sn as an attractive anode material for realizing ultrafast-charging batteries for electric vehicles and mobile devices.
采用原位电子显微镜对结晶锡柱进行了钠化处理，通过直接测量钠化速率来评估锡阳极的倍率性能。我们观察到，在相同条件下，锡阳极的钠化速率比硅阳极的锂化速率高两个数量级以上。钠-锡体系所表现出的前所未有的速率归因于在钠-锡扩散偶的薄界面处锡晶体的键合特性和晶态到非晶态的转变。在这里，我们通过解析钠离子在钠-锡界面区域的扩散过程以及结晶锡的电子结构，利用原子模拟解释了为什么锡阳极具有如此高的倍率性能。这项工作为将锡用作实现用于电动汽车和移动设备的超快充电电池的有吸引力的阳极材料提供了有用的见解。
