MoO2-MonX@C(X=C, S, N)异质结构的构筑及储锂特性研究

MoO2 is considered to be one of the ideal anode materials for lithium ion batteries, due to its high specific capacity, high electrochemical/thermal stability, and low cost. However, its cycle life and rate performance are restricted by the poor diffusion kinetics of lithium ions in bulk MoO2. In this project, the construction of MoO2-MonX@C (X=C, S, N) heterogeneous structures through the in-situ chemical conversion process of Mo complexes are proposed to solve this problem. In the targeted composites, the electrochemical kinetics and rate performance of MoO2 are expected to be improved by the “three-dimensional conductive networks” constructed by the hetero-interfacial electric field and the electric conductivity of carbon; while the electrochemical stability and cycle life should be improved by the structural stability of secondary assembled heterostructures. Combined with theoretical and experimental studies, by investigating the microstructures, compositions, interfacial properties, and electron/ion transport properties of heterostructure materials, this project aims to elucidate the key principles for the preparation of MoO2-MonX@C heterostructures from Mo complexes, reveal the interface effect and electrochemical synergistic mechanism of MoO2-MonX@C heterogeneous nanostructures, and further provide theoretical and experimental foundation for the design of heterogeneous composite electrode materials with excellent electrochemical properties, including high electrochemical activity and fast electron/ion transport ability.

由于比容量高、电化学/热稳定性高、价格低廉等优点，MoO2被认为是理想的锂离子电池负极材料之一。本项目针对体相MoO2中锂离子扩散动力学差的问题，拟通过钼配合物的原位化学转化过程构筑MoO2-MonX@C(X=C, S, N)异质结构，借助异质界面处的内建电场和碳材料的导电性构建“三维导电网络”，改善MoO2的电化学动力学和倍率性能；利用异质结构二次组装的结构稳定性，改善MoO2的电化学稳定性和循环寿命。结合理论计算和实验研究，考察异质结构的微观结构、组成、界面性质及电子/离子传输特性，揭示由钼配合物构筑MoO2-MonX@C异质结构的基本规律，阐明MoO2-MonX@C异质结构的界面效应和电化学协同增效机制，为具有电化学活性高、电子和离子传输快等优异电化学性能的异质复合电极材料的设计提供理论和实验依据。

通过耦合具有不同性质的化合物，构建具有界面效应和不匹配晶格的异质结构，是改善电极材料电化学动力学的有效策略之一；同时，异质结构的二次结构组装稳定性，可以改善电极材料的结构稳定性。本项目围绕异质结构的原位构筑、表征与作用机制，可控构筑了MoO2-Mo2C MXene@C、MoS2-V2C MXene@C、MoO2-Mo2C@C、Mo2C-Ni@C、Ni-MoO2、锐钛矿-TiO2(B)和锐钛矿-金红石异质结构材料。采用现代分析和表征技术，系统性阐述了异质结构的形貌、组成、电化学性能和电化学动力学；利用DFT计算，从分子水平上阐明了上述异质结构的结构、界面特性、离子吸附能、离子扩散动力学等。通过关联理论计算和实验结果，提出了上述异质结构材料的界面效应和电化学储能机制。最后，通过原位XRD、非原位扫描电镜等技术，考察了异质界面在充放电过程中的结构和组成稳定性，获取了具有高比能量、优异循环性能、稳定结构和组成的异质结构材料的设计与构筑新策略。另外，利用本项目的学术思想，也尝试构筑了纳米双金属催化剂及具有特定形貌的纳米电极材料，并研究了这些材料的性能。项目执行期间，项目负责人以第一作者/通讯作者身份在Nanoscale Horiz.、Chem. Eng. J.、Appl. Surf. Sci.、Inorg. Chem. Front.等国内外知名杂志发表SCI论文11篇，其中SCI一区论文6篇，1篇论文入选高被引论文；获得河南省自然科学优秀学术论文一等奖1项、河南省优秀科技论文二等奖1项。