全固态锂电池硫化物固体电解质/锂金属基合金负极界面特性与反应机制研究

In order to meet the increasing demands in energy density and safety performance for next generation batteries, the development of all-solid-state lithium metal batteries is unstoppable, and the electrode/electrolyte interfacial properties are crucial to ensure the high performance of the batteries. Herein, we focus on developing the new lithium metal based alloy anodes which deliver high energy density and are compatible with sulfide solid electrolytes. By selecting the magnetron sputtering targets (Mg, Al, Ga, etc.), the surface of lithium metal anode will be modified based on the alloy reaction and the interfacial side reactions between lithium metal anode and lithium sulfide solid electrolyte would be strongly suppressed resulting in a fast electron/ion conduction to prevent the nucleation and growth of lithium dendrites, so that the rate and cycling performance of the all-solid-state lithium metal batteries can be effectively improved. Meanwhile, the relationship between chemical composition, microstructure, interfacial characteristics and electrochemical performance of the electrodes and electrolyte will be systematically studied by applying the advanced nondestructive test techniques (Neutron tomography, X-ray absorption spectroscopy and tomography.) in order to reveal the morphological evolution, lithium storage and failure mechanism of the lithium metal based alloy anodes during cycling. The achievement in this project will provide theoretical and practical basis for designing new materials for all-solid-state lithium metal batteries.

为了满足日益提高的能量密度和安全性能等要求，锂离子电池的固态化已势不可挡，而锂金属及其合金负极与固态电解质良好的界面特性是保证电池优异性能的关键。本项目聚焦于开发可大规模应用、高能量密度、并且与高锂离子电导率硫化物固体电解质兼容的新型锂金属基合金负极材料。通过选择易与锂合金化的元素（Mg、Al、Ga等）利用磁控溅射对锂金属表面进行合金化处理以抑制锂金属与硫化物固体电解质之间的副反应，在锂金属/锂合金缓冲层/固体电解质界面构建电子/离子快速通道阻碍锂枝晶的形核与生长，实现全固态锂电池倍率和循环性能的有效提升。同时利用先进的无损检测技术（三维中子断层扫描成像，X-射线吸收谱及三维断层扫描成像）,系统分析材料的化学成分、微观结构、界面特性与其电化学性能间的构效关系，揭示锂金属基合金负极在电化学循环过程中的形态演变过程、储锂和失效机制，为实现其在下一代锂电池中的应用奠定良好的科学基础。

为了进一步提高现有商用动力电池的能量密度和安全性，锂离子电池的固态化已势不可挡，而锂金属负极与无机固态电解质之间界面的稳定构建是影响电池电化学性能的关键。本项目针对锂金属与高离子电导硫化物全固态电解质之间界面副反应等问题，利用自主设计惰性气氛保护的磁控溅射装置对锂金属表面进行改性，实现锂金属/硫化物固体电解质之间锂离子的快速稳定传导。通过选择易与锂合金化的元素（Mg, B和Ag）以及无机氧化物（Li3PO4和Al2O3）等在锂金属/硫化物固体电解质之间构建人工缓冲层，抑制硫化物固态电解质在低电位下的自发分解，从而阻碍锂枝晶的形核与生长，实现锂离子在循环过程中均匀的溶解与沉积。同时利用自主搭建的原位X-射线三维断层扫描成像表征平台和传统分析表征技术,系统研究了不同人工缓冲层化学成分、微观结构、界面特性与电化学性能间的构效关系，揭示了界面改性的锂金属负极与硫化物固体电解质在电化学循环过程中的形态演变以及失效机理，为下一代全固态锂金属电池的设计提供了方向和思路。