†State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China.
‡Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
Nano Lett. 2015 Jun 10;15(6):3879-84. doi: 10.1021/acs.nanolett.5b00705. Epub 2015 May 26.
In the past decades, Li ion batteries are widely considered to be the most promising rechargeable batteries for the rapid development of mobile devices and electric vehicles. There arouses great interest in Na ion batteries, especially in the field of static grid storage due to their much lower production cost compared with Li ion batteries. However, the fundamental mechanism of Li and Na ion transport in nanoscale electrodes of batteries has been rarely experimentally explored. This insight can guide the development and optimization of high-performance electrode materials. In this work, single nanowire devices with multicontacts are designed to obtain detailed information during the electrochemical reactions. This unique platform is employed to in situ investigate and compare the transport properties of Li and Na ions at a single nanowire level. To give different confinement for ions and electrons during the electrochemical processes, two different configurations of nanowire electrode are proposed; one is to fully immerse the nanowire in the electrolyte, and the other is by using photoresist to cover the nanowire with only one end exposed. For both configurations, the conductivity of nanowire decreases after intercalation/deintercalation for both Li and Na ions, indicating that they share the similar electrochemical reaction mechanisms in layered electrodes. However, the conductivity degradation and structure destruction for Na ions is more severe than those of Li ions during the electrochemical processes, which mainly results from the much larger volume of Na ions and greater energy barrier encountered by the limited layered spaces. Moreover, the battery performances of coin cells are compared to further confirm this conclusion. The present work provides a unique platform for in situ electrochemical and electrical probing, which will push the fundamental and practical research of nanowire electrode materials for energy storage applications.
在过去的几十年中，锂离子电池被广泛认为是最有前途的可充电电池，适用于移动设备和电动汽车的快速发展。钠离子电池引起了极大的兴趣，特别是在静态电网存储领域，因为其生产成本比锂离子电池低得多。然而，电池纳米级电极中锂离子和钠离子的输运基本机制很少得到实验探索。这种深入了解可以指导高性能电极材料的开发和优化。在这项工作中，设计了具有多接触的单纳米线器件，以在电化学反应过程中获得详细信息。这个独特的平台被用于原位研究和比较单个纳米线水平上锂离子和钠离子的输运性质。为了在电化学过程中为离子和电子提供不同的限制，提出了两种不同的纳米线电极结构；一种是将纳米线完全浸入电解液中，另一种是使用光刻胶仅将纳米线的一端暴露出来。对于这两种配置，在锂离子和钠离子的嵌入/脱嵌过程后，纳米线的电导率都降低了，这表明它们在层状电极中具有相似的电化学反应机制。然而，在电化学过程中，钠离子的电导率下降和结构破坏比锂离子更严重，这主要是由于钠离子的体积更大，并且在有限的层状空间中遇到的能量障碍更大。此外，还比较了硬币电池的电池性能，以进一步证实这一结论。本工作提供了一个独特的原位电化学和电学探测平台，将推动储能应用中纳米线电极材料的基础和实际研究。
