钠离子电池层状氧化物正极材料相变机理与稳定性研究

在众多电化学储能技术中，钠离子电池由于钠资源丰富、低成本、高安全、免维护等优点，在大规模储能领域具有广阔的应用前景。层状氧化物正极材料比容量高、合成简单、环境友好，是目前最有希望实现商业化的一类正极材料。由于钠离子的离子半径较大，钠离子在层状氧化物材料结构内部进行脱嵌时，造成这类材料的电化学反应和相变行为都比较复杂。而且层状正极材料在暴露空气时，水分子和二氧化碳会嵌入结构内部，引起结构发生不可逆的衰变。本项目将针对层状氧化物正极材料普遍存在的相变复杂和空气稳定性差的关键科学问题，通过晶体位点掺杂、空位无序构建、表界面结构调控等策略，结合先进的材料分析方法和理论计算指导，在多层次上（分子、纳米、微米）探究钠离子电池氧化物正极材料体系电化学工作中的相变机理、结构衰变机制，揭示限制层状正极材料电池性能的关键因素，为开发高性能钠离子电池层状正极材料和推进钠离子电池关键技术商业化提供科学指导。

Among many electrochemical energy storage technologies, sodium-ion batteries have shown great promise in grid-scale energy storage due to the abundant sodium resources, low cost, high safety, and maintenance-free. Layered oxides are considered as a class of promising framework compounds possessing a large specific capacity, simple synthesis and environmental friendliness, leading to their potential applications as positive electrode materials. Due to the large ion radius of sodium ions, sodium-intercalation layered oxide cathodes have to bear complex electrochemical behaviors and phase transition during the charge/discharge process. Moreover, when the layered cathode material is exposed to air, water molecules and carbon dioxide will be embedded in the structure, causing irreversible structural decay. This project mainly focuses on the complex phase transitions and poor air stability of layered oxide cathode materials. Through crystal structure site doping, vacancy disorder construction, and surface/interface structure control, combined with advanced material analysis methods and theoretical calculation, the phase transition mechanism and structural decay mechanism of layered oxide cathodes are investigated at multiple levels (molecules, nanometers, micrometers). This project provides scientific guidance for the development of high-performance layered cathode materials and the commercialization of key technologies for sodium ion batteries.