超分子辅助法构筑三维柔性锑基钠离子电池负极及性能调控方法与机制的研究

Sodium-ion batteries (SIBs) is one of the most promising candidates for application in large-scale energy storage fields due to the unique features of abundant resources and low-cost. Nonetheless, SIBs still face the serious problems of low capacity, low voltage, and poor cycling stability. In order to obtain high-performance SIBs, this proposal choose antimony-based anodes, with the advantages of high theoretical capacity, low and stable working potential, as the study objects. A novel and easy supermolecule-assisted approach is proposed to construct antimony/carbon composites with three-dimensional, flexible, and hierarchical micro-nanostructure. Meanwhile, metal-doping and surface modification is used to stabilize the structure of electrode interior and solid/electrolyte interphase. Consequently, the charge/discharge reversibility and cycling stability of the antimony-based anodes could be improved. In addition, the structure, composition, and morphology changes of the composite electrodes during charge/discharge as well as their physichemical and mechanical properties will be investigated for the purpose of disclosing the reaction mechanisms of hetero-metal doping and surface coatings in regulating the sodium-storage performance of antimony-based anodes. The implementation of this proposal will not only offer a supermolecular route for the synthesis of antimony/carbon-based anode materials, but also provide strong experimental foundation and scientific evidence for the optimization of their sodium-storage performance, thereby a promising anode material system can be presented for the development of SIBs.

钠离子电池（SIBs）因为材料来源丰富、成本低廉等突出优点成为大规模储能领域的最佳候选电源之一。然而SIBs仍面临着容量低、电压低和循环稳定性差等严重问题。为了获得高性能的SIBs，本项目拟以理论比容量高、工作电位低且平稳的锑基负极为研究对象，通过一种新型、便捷的超分子辅助法构筑三维柔性多级微-纳结构的锑/碳复合材料，同时利用金属掺杂和表面改性的手段来稳定电极内部结构和固体/电解质相界面，从而提高锑基材料的充放电可逆性和循环稳定性。此外，拟研究复合电极在充放电过程中的结构、组成和形貌变化以及其理化和机械性质，揭示多种异质金属掺杂和表面包覆层对锑基材料储钠性能的作用机制。该项目的实施不仅能够为锑/碳基SIBs负极材料的制备提供一种超分子法合成路线，而且为该材料的储钠性能优化提供有力的实验基础和科学依据，从而为SIBs 的发展提供一种候选的负极材料体系。

钠离子电池锑基负极材料在实际应用时的最大问题是在合金化反应中会发生较大的体积形变，导致电极结构的坍塌和电池循环性能恶化。该项目通过构筑出具有多级微/纳结构的锑基材料，并利用异质金属元素掺杂和界面调控等手段获得性能优异的钠离子电池负极材料。首先探索了一种便捷的阳离子交换合成法，实现了蛋黄-蛋壳和简单空心微球结构锑基材料的可控制备，对比研究了不同形貌结构材料的储钠性能；其次采用在工业领域被广泛应用的锑白为原料，找到了一种温和条件还原锑白制得不同晶相锑基纳米晶粒的便捷、可规模化和低成本的合成路线，研究了不同晶相的储钠性能；再次将铋元素掺杂进入锑基复合材料，实现铋和锑元素的协同储钠作用；此外研究了超分子法在制备锑基及钼基钠离子电池负极材料中的应用，通过控制超分子热解反应的气氛和温度，获得了不同晶相和形貌结构的复合材料，对比研究了其储钠性能，分析了储钠性能改善的作用机制。研究结果表明，具有复杂中空内部结构的蛋黄-蛋壳微球比简单的空心微球更有利于维持电极在长期储钠过程中的结构稳定性，还利于提高电极的空间利用率；纯Sb相与纯Sb2O3相和复合相Sb2O3/Sb相比，显示出最为平稳的脱钠电位平台，在低电位下的储钠容量也最高，循环性能也最优异，说明纯Sb相更适合在钠离子电池负极中的实际应用；通过超分子法制备复合材料步骤简单，易于操作，而且构筑出的材料具有嵌入式的多级微纳结构，能大幅度提高储钠性能。该项目的实施，为不同形貌结构锑基材料的储钠能力提供了科学解释，为高性能钠离子电池锑基负极材料的设计合成和发展方向提供了一种思路，为超分子法在钠离子电池负极材料合成中的应用提供了一种方案，并且所研发的液相还原工业级锑白制得锑纳米晶粒在合成方法和储钠性能上都具有很好的应用前景。