高效长寿命锂空气电池锂基负极的制备及界面电化学研究

Lithium-air battery caused much attention as one of the most promising power sources that can be utilized in various areas due to its advantages, such as high energy density, low-cost and environmental friendly, etc. The specific capacity, energy efficiency, safety, and cycle performance of lithium-air battery are largely dependent on the lithium-based anode which requires the properties of large capacity and low (dis)charging potential. The objective of this proposal is to enhance the stability and coulombic efficiency of lithium-air battery, based on clarifying the mechanism of reactions occurred at lithium/electrolyte interface, especially decomposition and inhabitation of lithium dendrites in oxygen and dry air atmosphere. Besides, it is practicable to solve/reduce the volumetric effect through optimizing the lithium-rich alloys synthesized by lithium chemical pre-doping. The effects of components, concentration, the oxygen solubility of electrolyte and additive agent, as well as that of the components of air, on the lithium-rich alloy electrode/electrolyte interfacial reactions will be systematically studied in this project. The model of lithium-air battery with improved cycling life, efficiency, and energy density will be developed with the optimized anode/electrolyte system. The achievements of these studies will definitely promote the performance of lithium-air battery and pave the way for its final applications.

锂空气电池以其能量密度高、成本低和对环境友好等优势受到广泛关注。大容量、低电位锂基负极是锂空气电池高比能量的重要来源，同时也对该体系储能效率、安全性和循环稳定性起重要影响。本项目从研究锂空气电池条件下金属锂和电解液界面反应机理入手，探明氧气及干燥空气气氛下金属锂枝晶生长、抑制以及溶解析出反应效率问题，探寻提高金属锂稳定性和库伦效率的方法；另一方面，创新地利用化学预嵌锂方法制备多种富锂合金负极，以解决锂空气电池中金属锂负极的体积效应强、库伦效率低的问题。利用一系列电化学手段研究富锂合金和电解液界面反应规律，分析电解液组成成分、浓度、氧溶解度和添加剂等对界面反应的影响，同时考察空气环境中其他成分在负极表面的作用机制。利用优化好的负极/电解液体系制备软包装锂空气电池原型，显著提升锂空气电池的储能效率、循环寿命和实际能量密度。本项目的实施将为锂空气电池实用化打下坚实的研究基础。

本项目主要关注于锂空气电池锂基合金的制备方法，电化学特性及其与电解质相容性研究。项目实施过程中设计与制备了一系列相应的正极材料：包括纳米钌修饰的三维多阶孔道石墨烯气凝胶，单晶氧化镍，碳化菌丝自支撑正极，铂碳催化正极，纳米多层氧化铁/石墨烯复合材料。利用气氛保护机械球磨方法制备锂硅合金负极来提高负极循环效率和安全性。利用相关原位电化学方法研究空气中O2气氛下的电极电化学行为。我们发现在O2气氛下，金属锂充放电的库伦效率高达99.5%以上，循环寿命超过1000圈。通过界面表征得知金属锂在氧气气氛下表面产生氧化物和磺酸盐组成的SEI膜。设计和优化金属锂负极/固体电解质界面。在LAGP表面溅射一层纳米锗薄膜，一方面抑制四价锗的还原，提高锂/固体电解质界面稳定性，另一方面使得电解质和金属锂接触更紧密，减小金属锂/固体电解质的界面阻抗。项目研究期间在Energ Environ Sci, Advanced Energy Materials, Energy Storage Materials等国际著名期刊上发表SCI论文共计28篇（论文清单另附）。申请发明专利2项。培养研究生12名。该项目的顺利完成为锂空气电池实用化提供了坚实的理论基础。