基于层状锰氧化物正极的可充水系锌电池研究

Rechargeable aqueous zinc batteries (AZBs) are highly desirable for large-scale energy storage owing to their low cost and high safety. However, the diffusion of multivalent cations in traditional host lattice is difficult, due to the higher charge and heavier mass of Zn2+ as compared to Li+. Therefore, it is improtant to develop high performace cathode materials for AZBs. Herein, this project will select two typical layered Mn-based oxides (i.e. birnessite δ-MnO2 and chalcophanite ZnMn3O7·nH2O) as Zn-storage cathodes, which feature materials abundance, multiple oxidation states of Mn, and the large layered structure suiting for the intercalation of Zn2+. The morphology and structure of the layered Mn-based oxides can be controlled by the selected preparation methods, such as hydrothermal process, electrochemical deposition, and chemical coprecipitation technique. Moreover, this project will elucidate the relationship between the micro-structure and the electrochemical performance of the suggested cathodes. In addition, this project plans to highly improve the Zn-storage capacity, cycling stability and rate capability of the Mn-based oxides cathodes by designing nanostructure, introducing buffering matrix, and optimizing aqueous electrolyte. Furthermore, this project will summarize the critical factors for this type materials with enhanced Zn-storage properties. In addition, the reaction mechanism of the suggested cathodes and the function of the water in the layered structure will be revealed. The achievement in this project will provide the theoretical guidance and technical approach for developing new cathode materials with high performance.

可充水系锌电池具有资源丰富、安全性高等特点，其在大规模储能领域展现了良好的应用前景。然而，锌离子电荷高且原子量大，在常规正极的晶体结构中脱嵌动力学缓慢，因此急需开发新型高性能储锌正极材料。本项目以两种典型层状锰氧化物正极（水钠锰矿δ-MnO2和黑锌锰矿ZnMn3O7·nH2O）为研究对象，其具有较大的层间距，有利于锌离子的可逆脱嵌。采用几种合成方法（水热、电沉积、化学共沉淀等），并优化实验条件参数，实现对材料晶相、组成、形貌、尺寸和结构的调控，结合电化学分析手段，揭示材料微观结构和性能间的构效关系。通过纳米化、材料复合、水系电解液优化等方法，解决锰氧化物正极反应活性低、循环寿命短和倍率性能差的问题，凝练出具有一定普适性的电极材料改性规律，并阐明层状锰氧化物正极的储锌机制和层间结晶水对锌离子脱嵌行为的影响规律，为实现其在水系锌电池中的应用以及新型高性能储锌正极的研制提供理论依据和技术途径。

水系锌电池资源丰富、安全性高在大规模储能领域具有重要应用前景，但缺乏长寿命、高比能正极材料。本项目围绕可充水系锌电池正极开展系统研究，涉及材料可控制备、结构调控、机理研究、电解液优化、器件组装、性能评估等研究工作。发展了层状锰氧化物纳米正极材料制备新方法，探究了不同电解液体系对其电化学行为影响，揭示了阳离子掺杂对层状锰氧化物正极材料电化学反应活性、结构稳定性的影响规律。此外，设计制备了高容量层状钒氧化物正极材料，并揭示了其储锌机理和电化学反应动力学，并构筑了软包可充锌电池器件；探索了几种高电压聚阴离子型磷酸盐正极以及层状石墨正极在可充锌电池中的应用，揭示了其电化学储能规律，拓宽了可充锌基电池正极材料的选择范围。相关研究成果为可充锌电池关键功能材料的研制提供了理论和实验依据。在项目资助下，以第一（含共一）/通讯作者在Chem. Sci., Adv. Funct. Mater., Energy Storage Mater., Chem. Eng. J., Chem. Commun. 等国内外期刊发表SCI论文15篇；围绕可充水系锌电池材料化学领域，以第一作者在Chem. Soc. Rev.发表综述论文1篇；以第一发明人获中国发明专利2项（已授权）；受邀参加中国化学会年会、全国电化学大会、国际电化学能源系统会议等学术会议并做学术报告，圆满完成了预定目标。