水溶液中钠离子的嵌入反应及其电池应用研究

Sodium ion batteries are considered as promising energy storage system for the future large-scale applications because of the natural abundance of sodium resources. However, the existing sodium ion batteries mainly use flammable organic electrolyte, which would cause serious safety hazards as reported in Lithium ion batteries, thus, would retard the industrial development of this technology. Here, we put forward a new idea of developing aqueous rechargeable sodium ion batteries with superior safety properties.This research project is oriented to design and synthesis a series of sodium base electrode materials, such as transition metal cyanide complexes cathodes, NaTi2(PO4)3, NaxTiO2 anodes, by taking into consideration of the special structural requirement for aqueous electrolyte, then study their Na-intercalation performances and kinetic characteristics, the relationship between the electrode structure and their properties, and develop several useful electrodes with high capacity and excellent cycling stability. On the basis of above researches, we will construct several new aqueous rechargeable sodium ion batteries by combining cathode with anode materials, and investigate their electrochemical properties in the aspect of capacity, efficiency, cycle life, energy density and etc. These researches are expected to provide some knowledge and technical support for the development of advanced electrochemical energy storage systems.

基于钠丰富的自然资源，钠离子电池被认为是未来大规模储能电站的理想配套电源。然而目前所报道的钠离子电池，仍主要沿用易燃的有机电解液体系，存在着与锂离子电池类似的安全隐患，难以完全满足储能领域的应用要求。为此，本项目提出基于水溶液电解质体系，发展高安全性钠离子电池的新思路。项目拟在前期工作基础上，根据水溶液电解液对储钠电极特殊的结构和性能要求，重点选择过渡金属氰根配合物正极、NaTi2(PO4)3、NaxTiO2等嵌入负极为研究对象，考察其在水溶液体系中的嵌钠反应行为，发展出兼具高容量和良好循环稳定性的储钠电极材料. 在此基础上, 构建几类新型水溶液钠离子电池，研究正负极材料在容量、效率、反应动力学等方面的匹配性，考察电池的循环性、自放电、能量与功率特性等，完善水溶液钠离子电池的技术原理。项目研究成果可为新型电化学储能体系的发展提供新的技术方向和基础材料的支持。

水溶液钠离子电池具有资源丰富、成本低廉等优点，在规模储能领域表现出诱人的应用前景。通过本项目的实施，我们开发了一系列具有三维离子隧道结构的普鲁士蓝类化合物Na2MFe(CN)6(M=Ni, Cu, Fe, Co)作为高容量、长寿命的水系储钠正极，探索了普鲁士蓝材料储钠性能与晶格结构的相互关系，从抑制结构缺陷，提高晶格规整度等方面对普鲁士蓝材料进行了优化。同时，我们设计合成了两种水系储钠负极，NaTi2(PO4)3/C纳米复合物及聚酰亚胺PNFE有机材料，探究了其在水溶液中的氧化还原反应机理，实现了低电势下的高容量可逆储钠性能。最后，我们将普鲁士蓝正极材料与NaTi2(PO4)3负极匹配，构建了几类高比能的水溶液钠离子全电池。其中，Na2CoFe(CN)6-NaTi2(PO4)3全电池体系的平均工作电压为~1.4 V， 能量密度高达~67 Wh kg-1，并实现了高倍率、长寿命稳定循环，有望发展成为具有应用前景的大规模储能体系。