亚稳态层状硒氧化物MSeO3∙H2O的快速非晶化及其储锂机制研究

The rapid decrease on Li+ storage capability and cycling stability of anode materials in lithium ion batteries (LIBs), has hindered their widespread application on electric vehicles (EVs) and hybrid electric vehicles (HEVs), etc. In this project, we propose a new strategy that fast amorphization in layered MSeO3∙H2O (M = Co, Fe, Ni, Mn, Cu) series induces ultrahigh-rate capability on lithium ion storage. The rational synthesis and composition, structure modulation of metastable MSeO3∙H2O with layered crystal structure will be developed. The fast amorphization of these compounds would minimize volumetric change and electrochemical strain during charge/discharge process, resulting in superior high-rate performance. We will study the phase and morphology evolution of metastable MSeO3.H2O during the lithium ion insertion/extraction process in detail. The formation of SEI film, lithium ion transport pathway will be investigated carefully to reveal the enhanced mechanism of fast amorphization on lithium storage kinetics. The effect of crystallographic water on lithium storage performance will be illustrated further. By the optimization of chemical composition and coupling effect of the transition metals in this layered MSeO3.H2O series, their “morphology-composition- structure- lithium storage properties”will be clarified clearly. We believe that the success of this project will provide important theoretical basis to obtain high-rate capability for power LIB anodes.

高倍率充放电速率下负极材料容量和循环稳定性急剧衰减，成为制约动力型电池发展的瓶颈因素而亟待解决。本项目提出“层状亚稳态层状物质的快速非晶化以实现高倍率储锂”的新思路，探索和发展MSeO3.H2O(M = Co, Fe, Ni, Mn, Cu) 层状材料的可控合成、元素组成、结构调变及其与储锂性能的关联，利用其快速非晶化特性缓解储锂过程当中的体积变化，以实现高倍率性能。将深入研究该系列材料在嵌锂和脱锂的过程中的相结构演变、显微形貌变化、SEI膜的形成、锂离子输运机制及结晶水的存在方式，揭示非晶化对于增强储锂动力学的关联性。在此基础上合理调配过渡金属元素并优化其组合，认识MSeO3.H2O系列材料的“形貌-成份-结构-储锂性能”整体性框架规律，为低成本、高性能动力型负极材料的获得提供新的方法和理论依据。

基于本项目所提出的“亚稳态层状物质的快速非晶化以实现高性能离子存储”这一研究思路，成功实现了3d过渡金属硒氧化物MSeO3和硒化物MSex(M=Ni,Zn,Co,Cu,Mn,Fe) 类材料的可控合成、成分调控和结构演变，揭示了不同过渡金属元素的成分和非晶化过程对其电化学性能的调控规律，归纳出过渡金属硒氧化物的”成分-结构-锂离子存储性能”之间的关联性。经过优化之后的钴基过渡金属硒氧化物在0.2Ag-1低放电倍率下展现出2713.7 mAhg−1的高容量，并且倍率性能优异：在3Ag-1高倍率下充放电循环1000圈之后储锂容量能够保持在1100mAhg-1，超出目前性能最佳的Si-C负极高倍率容量的两倍。在此基础上，将3d过渡金属硒化物的应用拓展到水系锌离子电池和电催化领域，分别开发了长循环性能优异的硒化钒材料应用于水系锌离子电池；以及高效、稳定的硒化物HER、OER电催化剂，利用非晶化的设计理念提升了其催化活性，验证了非晶态结构增强电化学性能这一规律的普适性。. 以上研究工作为过渡金属硒氧化物的设计合成、结构与电化学性能之间的构效关系提供了清晰的认识，丰富和发展了硒化物类材料的其电化学应用，为锂离子电池、水系锌离子电池、HER/OER电催化剂提供了新的材料体系。在本项目资助下，总共在Adv.Mater(1); Angew.Chem.Int.Ed.(1);Energy Environ.Sci.(1);Adv.Energy Mater.(3);Adv.Funct.Mater.(1);ACS Nano(1)等重要国际期刊上发表SCI论文20篇，其中3篇论文选作Adv.Energy.Mater.期刊的封面,1篇论文选作Adv.Funct.Mater.期刊的封面，2篇论文入选ESI高被引论文。授权国家发明专利1项。相关研究结果被Materials Views、WileyChem、X-MOL、能源学人等媒体专题报道。