金属锂电沉积和溶出的原位AFM研究及调控

电极/SEI界面是锂发生电沉积的场所，其成核和生长行为深受SEI、特别是与电极构成界面的SEI内侧结构和性质的影响。现有研究多着眼于SEI整体性质及其对锂负极性能的影响，而电极/SEI界面及其对锂沉积的影响机制尚缺乏深入研究；尤其是传统马赛克SEI复杂多相的特点给理解和阐明锂负极界面过程带来困难。本项目拟发展原位AFM结合电化学方法的策略，从宏观特征和微观细节两个方面研究和调控SEI的形成及对锂沉积-溶出行为的影响。一方面，调控电解液锂离子溶剂化结构，构建结构确定的模型化SEI，为研究电极/SEI界面影响提供基础；另一方面，运用原位AFM揭示SEI演化及其对锂沉积-溶出的影响机制，同时结合电化学方法获得发生在电极/SEI界面的锂初期成核-生长宏观信息，弥补SEI存在下AFM研究锂初期沉积的困难性。本项目从根源上探索锂的沉积-溶出过程及电极/SEI界面的作用，为构建高效稳定的锂负极提供指导。

The lithium deposition and dissolution occur at the interface between metal and SEI. The nucleation and growth behaviors of Li metal at such interfaces are significantly affected by the structure and properties of the SEI, especially the inner side of the SEI that forms the interface with the metal. Most of the existing studies focus on the overall properties of SEI and their effects on the performances of Li metal anodes. Whereas, the influences of metal/SEI interface and its mechanism on Li deposition have not been thoroughly investigated. Particularly, the traditional mosaic-type SEI with complex multiphase nature place difficulties in elucidating the processes of Li deposition-dissolution at the metal/SEI interface. Herein, this project aims to combine in situ atomic force microscopy (AFM) and electrochemical methods to study the formation of SEI and its effect on lithium deposition and dissolution processes by integrating macroscopic features and microscopic details. On one hand, various kinds of model SEIs with adjustable structures will be constructed by the rational regulation of electrolyte reaction kinetics correlated with optimizing solvation structure of Li ions in electrolyte, providing a basis for studying the influences of metal/SEI interface on Li deposition and dissolution. On the other hand, the evolution of SEI and its mechanism on Li deposition-dissolution will be characterized by in-situ AFM. Meanwhile, the macroscopic behavior of the initial Li nucleation and growth at the metal/SEI interface will be further obtained by electrochemical transient techniques to compensate the lack of information due to difficulty investigating initial Li deposition behaviors in the presence of SEI by AFM analysis. This work explores the fundamental processes of Li deposition and dissolution and the role of the metal/SEI interface on the abovementioned processes, which provides guidance for the construction of efficient and stable Li metal anodes.