高安全性钠离子固态电解质的组分设计及其离子传输机制研究

The room temperature Na-ion battery has been under focus lately as potentially low-cost, environmental-friendly technology for use in large-scale energy storage systems. However, safety issues related to the use of traditional combustible organic electrolytes are of great concern. It is anticipated that such safety issues can be fully addressed through the use of non-flammable solid electrolytes in solid-state batteries. Development of NASICON-based solid electrolyte with high ionic conductivity is still challenging to achieve. In this proposal, we develop a NASICON-based superionic conductor Na3+xGaxZr2-xSi2PO12 designed for use in a high safety sodium battery for the first time. The role of substitution gallium for zirconium in phase transition, conductivity and ion transport mechanism of Na3Zr2Si2PO12 will be addressed. A solution-assisted solid-state reaction method will be developed. The new Na-ion solid electrolyte, Ga-substituted Na3Zr2Si2PO12, is supposed to achieve high ionic conductivity of 10-3 S/cm. The proposed work will provide new avenues for developing high safety sodium batteries.

发展规模储能应用的钠离子电池技术具有重要战略意义。钠离子电池采用液态电解质存在着易泄露、安全性差与可靠性低等问题，用固态电解质取代液体电解质有望彻底解决电池的安全性问题。本项目以NASICON结构的固态电解质为研究对象，针对Na3Zr2Si2PO12材料存在离子电导率低的关键问题，开发低温液相反应-高温固相反应复合制备技术，制备纯相、致密度高、结晶度高、晶粒尺寸小、无晶界微裂纹的电解质陶瓷。开展组分设计研究，基于Ga3+的八面体倾向性，设计NASICON结构Na3+xGaxZr2-xSi2PO12材料体系，系统研究NASICON材料体系的成相机理、组分设计与离子传导性能的构效关系、离子传输机制等关键科学问题，最终开发一种新型钠离子固态电解质材料，将室温离子电导率由10-4 S/cm水平提高到10-3 S/cm以上，并揭示其离子传输机制，为高安全性固态钠离子电池的应用打下理论和技术基础。

固态钠电池具有安全性高、能量密度高的优点，是一种具有广泛应用前景的新型储能技术。作为关键材料，NASICON型Na3Zr2Si2PO12固态电解质存在离子电导率低等问题。围绕本项目规定的任务，一方面设计Na3+xZr2-xGaxSi2PO12 (0≤x≤0.4)材料体系，利用Ga3+掺杂Zr4+调控载流子浓度和晶体结构；另一方面，利用低成本棉花作为模板，低温制备管状Na3Zr2Si2PO12，应用于有机-无机复合电解质中。结果表明，Ga3+取代Zr4+，可以扩大钠离子迁移的“瓶颈”尺寸，Na3.1Zr1.9Ga0.1Si2PO12在25℃的离子电导率高达1.06×10-3 S/cm。管状Na3Zr2Si2PO12与聚环氧乙烷、聚偏氟乙烯-六氟丙烯制备成的复合电解质在25℃的离子电导率、迁移数、电化学窗口分别为6.93×10-4 S/cm、0.882、5 V，优于Na3Zr2Si2PO12纳米颗粒。本项目的开展为高性能固态钠电池的研究奠定基础，设计Na3+xZr2-xGaxSi2PO12材料体系、管状Na3Zr2Si2PO12/聚环氧乙烷/聚偏氟乙烯-六氟丙烯复合电解质、纳米晶Na3Zr2Si2PO12致密陶瓷，丰富了固态钠离子电解质的研究领域。该项目已发表论文13篇，其中12篇为SCI收录，1篇为中国科技核心期刊，此外还有审稿中和完稿的2篇英文研究论文，授权中国发明专利1项，合作出版英文科技著作1部，培养硕士研究生2名。