多酸基金属-有机框架材料的合成及其在钠离子电池负极中的应用

Concerns have been raised about the future availability of lithium and its future cost, especially in light of the projected orders-of-magnitude increase in lithium usage for batteries in consumer electronics and electric vehicles. In view of the similar physical/chemical properties of sodium with lithium, sodium-ion batteries are among the most promising alternatives to lithium ion batteries. Unfortunately, sodium-ion storage materials are rare in comparison to lithium-ion storage materials, especially for anodes, because Na+ has a much larger ionic radius than Li+. This larger radius frustrates the insertion/extraction of Na+ in the graphite-based anodes commonly explored in lithium ion batteries. This project proposes to synthesize polyoxometalate-based metal-organic frameworks (POMOFs) directly or using the POMOFs/GO composite as the anode materials for sodium-ion batteries firstly. We choose POMOFs because these crystalline materials both have the porous characterization of MOFs (tunable porosity and suitable for Na+ insertion/extraction) and the electrochemical property of POMs (multi-electron.redox transformations). The structural characterization and electrochemical performance data will be studied. This project will discuss the influence of different parameters on the electrochemical performance, including the precursor composition, the component, structure and testing conditions of these materials, and seek for new electrode materials with high-capacity and high-stability electrode materials for sodium-ion batteries.

随着消费类电子设备以及电动汽车成数量级的增加，锂资源的匮乏与昂贵便成了不可回避的问题。鉴于钠和锂有着极其相似的物理和化学性质，钠离子电池被认为是最有希望取代锂离子电池的下一代储能电池之一。然而，与储锂相比，能够储钠的材料很少，尤其是负极材料。因为钠离子的半径要比锂离子大很多，更大的半径限制了钠离子在常用锂离子电池石墨基负极材料中的嵌入和脱出。本课题首次提出利用多酸基金属-有机框架纳米材料（POMOFs）直接或者与石墨烯复合作为钠离子电池负极材料。我们选择POMOFs是因为其兼具MOFs的多孔特点（孔道大小可调，适合钠离子嵌脱）和POMs的电化学特性（多电子的氧化还原性质）。本项目将对所得材料进行结构表征和电化学性能测试，还将探讨不同的前驱体的组成、催化材料成分、结构以及测试条件对其作为钠离子电池负极材料性能的影响，寻求质量比容量高、循环稳定性好的新型钠离子电池负极材料。

本项目围绕新型锂（钠）离子电池负极材料以及新型全固态电池电解质材料的研究展开。以材料的表、界面结构调控为手段，探索锂（钠）离子电池新型负极和固态电解质材料；从电化学和微观角度分析负极材料储锂（钠）机理以及锂（钠）离子在固态电解质材料中的迁移规律，为新型锂（钠）离子电池负极和电解质材料的设计提供理论依据。 (1) 通过不同的多酸和MOF材料的适配，实现电极材料结构及成分的调控，并通过一锅法巧妙制备出了多酸基MOF（[PMo12O40]3-@ZIF-67），研究了该多酸基MOF衍生物作为锂（钠）离子电池电极材料的可能性，揭示了Co3O4/CoMoO4纳米杂化材料的储锂机理；(2)同时开展了MOF（UIO-66-NH2）用于全固态锂（钠）离子电池复合电解质方面的工作，通过选取适当的填料，巧妙运用路易斯酸碱理论，采取固定阴离子的办法，显著改善了锂离子的离子迁移数。本项目对产业化以及基础理论都有一定的实际意义。