富锂正极氧离子氧化还原反应及其与功能电解质溶液间的相互作用

Li-rich cathode has high specific capacity, but suffers from oxygen evolution, crystal structure destruction and performance decaying. A new solution based on the application of functional electrolytes is proposed in this project. The possible intermediates and reversibility of oxygen ion redox reactions, and their influences on the crystal structure changes and charge/discharge performances of Li-rich cathode; the coordination, reaction activity, reaction paths, and reaction products between the intermediates and the compositions of electrolytes; and the influences of the molecular structure of functional electrolyte additives on the redox reactions of oxygen ions and the crystal structure and charge/discharge performances of Li-rich cathode, will be investigated by theoretical calculations, in-suit spectroscopic techniques and electrochemical measurements. The mechanisms on the redox reactions of oxygen ion and their interactions with the compositions of functional electrolytes will be illustrated. It is possible to control the redox reactions of oxygen ions for contributing to the reversible capacity and to improve charge/discharge cycle performances through the application of functional electrolytes with combining the optimizations of the composition and structure of Li-rich cathode. These investigations will be beneficial for solving the issue of interfacial instability of electrode/electrolyte when Li-rich cathode is used in practice and new high energy batteries are developed, and enrich the interface electrochemistry.

锂离子电池富锂正极比容量高，但存在氧气析出、晶体结构破坏、循环性能衰退等问题。本项目基于申请人前期的研究基础，提出功能电解质溶液的解决方案。拟结合理论计算、原位谱学技术及电化学测量，研究富锂正极氧离子氧化形成的各种可能中间态、氧化还原可逆性、及其对材料晶体结构演化和充放电性能的影响；氧离子中间态与电解质溶液组分间的配位方式、反应活性、反应路径及反应产物；以及电解质溶液功能添加剂分子结构对氧离子氧化还原反应及富锂正极晶体结构和充放电性能的影响。阐明富锂正极氧离子氧化还原反应机理及其与功能电解质溶液各组分间的相互作用规律。通过功能添加剂的应用并结合材料组成和结构的优化，实现对氧离子氧化还原反应的可控，使之贡献于富锂正极的可逆容量但避免氧析出，提高充放电循环性能。相关研究，不但为富锂正极的实际应用而且为发展高能电池解决电极/电解液界面不稳定性问题提供新的解决方案，也将丰富界面电化学科学的内容。

项目结合理论计算、原位谱学技术及电化学测量等方法，研究了锂离子电池富锂正极材料的组成和结构在充放电过程中的演化过程以及电解质溶液组分（溶剂、锂盐和电解液添加剂）在锂离子电池电极上的分解过程，阐明了富锂正极与电解液各组分间的相互作用规律。在此基础上，提出系列电解液添加剂，构建电极/电解液界面膜，解决电极材料高低温稳定性能差的问题，阐明了电解液添加剂的分子结构对电极/电解液界面膜的热、机械稳定性及离子导电性的关系。项目累计发表论文31篇，申请发明专利5件，培养博士后、研究生24人。部分研究成果已在一些企业获得实际应用，包括“提高电池充电电压的电解液添加剂”成果在广州天赐高新材料股份有限公司应用；“提高钴酸锂电池循环稳定性的电解液添加剂”成果在珠海冠宇电池股份有限公司应用。