金属掺杂过渡金属二硫（硒）化物-碳量子点复合材料的制备及其钠离子电池负极性能研究

Transition metal dichalcogenides MX2(M=Mo, W and X=S, Se) is considered as an ideal kind of candidate as anode materials for Na-ion batteries (SIBs) owing to the large interlayer spacing and high specific capacity. However, the MX2 material usually suffers from the obstacles of poor electronic conductivity, bad rate capacity and cycling stability. Focus on these problems, the alien metal elements-doped MX2-C dots composite material will be designed to enhance effectively the electrochemical performances of MX2 as anode for SIBs. Firstly, the electronic conductivity and the stability of two-dimensional layered structure might be improved fundamentally due to the introduction of alien metal elements which can change the energy band structure of MX2. And also the Na+ chemical diffusion coefficient of the MX2 electrode can be increased because of its crystal structure evolution. Furthermore, the rate capacity and cycling stability will much better enhanced prominently via introducing C dots.. Various metal-doped MX2 and metal-doped MX2-C dots composite with all kinds of characters can be prepared through controlling different experimental parameters (such as temperature, mixed mode combination and so on). As a result, the controllable preparation of metal-doped MX2 and metal-doped MX2-C dots composite will be reached. Additionally, the relationship between the alien metal elements of electrode materials and their electrochemical performances will be discussed in this project. The synergistic action among alien metal elements, C dots and MX2 materials will also be studied to clarify their contribution to energy storage. Hence, the metal-doped MX2-C dots composite with outstanding electrochemical characters will be obtained for SIBs. Moreover, the Full-Cell SIBs with excellent cycling stability and high power density will be designed through optimizing the structure of device. The strategy provided by this program would be helpful for MX2 to apply in the next-generation SIBs anode materials.

过渡金属二硫/硒化物（MX2）作为钠离子电池（SIBs）负极材料存在着电导率低、倍率和循环性能差的问题。本项目提出首先对半导体MX2实施金属掺杂，通过掺杂调节MX2的物相结构和能带结构，提升MX2的电导率和层状结构的稳定性，提高Na+在MX2体相中的扩散系数；然后将金属掺杂MX2与碳量子点以适当方式复合，获得金属掺杂MX2-碳量子点复合材料，使MX2作为SIBs负极的倍率性能和循环性能获得根本改善。基于此，本项目将研究金属杂原子对MX2的掺杂方式和金属掺杂MX2与碳量子点复合的工艺条件，探讨掺杂金属的种类、掺杂量、存在形式等对MX2储钠性能的影响规律，揭示复合材料中掺杂金属、碳量子点及MX2三者对提升复合材料储钠性能的协同作用机制，优化工艺条件，获得储钠性能优异的金属掺杂MX2-碳量子点复合材料，并组装循环性能稳定、倍率性能优异的钠离子全电池。

本项目针对过渡金属二硫/硒化物MX2电导率低、储钠倍率性能和循环稳定性差的问题，提出对MX2实施合适方式的金属掺杂，调节其电导率，提高Na+在其体相内的扩散系数，提升材料层状结构的稳定性；并通过进一步与碳量子点的复合，在掺杂金属、碳量子点以及MX2三者之间的协同作用下，获得储钠性能优异的MX2复合材料。但是，在项目实施过程中，由于过渡金属二硫/硒化物MX2对热处理温度非常敏感，实施金属掺杂时容易导致杂相产生，难以实现对MX2进行金属掺杂的精确控制。但本项目在过渡金属硫（氧）化物-碳复合材料的制备及储钠性能研究、硫掺杂有序中孔碳的制备及层间距调控和储钠性能研究、碳材料的缺陷诱导非金属掺杂及电化学应用研究、Fe基化合物-碳复合材料的制备及电化学应用研究、MoSe2-石墨烯复合材料的制备及储锂性能研究等方面取得了系列成果。. 研究成果在国际国内学术期刊发表学术论文17篇，申请国家发明专利5项、获授权1项。项目研究成果中关于“碳纳米材料非金属掺杂效率提升的刻蚀诱导机制及其储能性能”、“氮硫共掺杂纳米碳-金属硫化物（NS-C/ MS）复合材料中C-S-M键的形成机制和C-S-M键改善复合材料储锂/钠性能的作用机制”和“多孔碳的过渡金属高分散掺杂及载硫性能”等部分的内容，是2020年度湖南省自然科学奖二等奖（20202170-Z2- 416-R01）的核心支撑。. 另外，项目研究培养硕士研究生6名（2名2022年春季毕业），2篇论文获评为湖南省优秀硕士论文。. 项目部分预定研究目标未完全实现，但研究成果完成指标大幅超过了既定目标。