基于高导电性钼基负极材料的柔性钠离子电容器的构筑与性能研究

Flexible sodium-ion capacitor as a burgeoning energy storage configuration that combines high power density, high energy density, and long cycle life has been attracting tremendous attention. Realizing high-performance sodium-ion capacitors has the particular challenge of matching both capacity and kinetics between the battery-type anode and the capacitor-type cathode. Recently, some transition-metal compounds have been found to show pseudocapacitive characteristics in a nonaqueous electrolyte, which makes them interesting high-rate candidates for sodium-ion capacitor anodes. However, achieving high-performance for high mass loading pseudocapacitive materials has been a great challenge because of the sluggish electron and ion migration kinetics through the thick electrode materials. In order to address this problem, reasonable structural design, interfacial stabilization, and high electronic conductivity was proposed in this project. We plan to prepare high intrinsic conductivity of molybdenum base electrodes via introduction of oxygen vacancies, doping, or synthesizing metallic compounds, to enhance the energy density and rate capability of highly loaded molybdenum base electrodes. In addition, we will also fully evaluate the electrochemical properties of the as-prepared pseudocapacitive materials by employing various in(ex)-situ technologies when used as anode materials for sodium-ion capacitors, and further obtain the scientific relationships and rules between nanostructures and electrode kinetics, ionic/electronic transportations, characteristics of interfaces. After finished this project, we can not only improve the electrochemical properties of the related high-capacity anode materials, but also promote the rapid development of flexible sodium-ion capacitors

柔性钠离子电容器的柔性化、高能量密度和潜在价格优势使其成为了超级电容器领域新的研究热点和发展趋势。插层式赝电容的发现为解决钠离子电容器两电极之间电荷传递动力学的匹配问题提供了新的思路，具有重要的研究价值。本项目拟在前期电极纳微结构调控和稳定化表界面的基础上，重点研究通过氧空位调控、掺杂、制备具有金属性材料三种策略制备高本征导电性的钼基赝电容材料，实现高负载量下柔性电极比容量和倍率性能的显著提高。此外，在可控制备基础上，将借助各类（非）原位表征技术，探明各电极材料结构特征改善储钠性能的科学规律，为开发高性能柔性钠离子电容器奠定科学和物质基础。

在本项目的支持下，我们制备了多种高导电性钼基复合纳米材料，如还原氧化石墨烯铰链氮、硫共掺杂空心碳球包覆硒化钼/硒化钴复合材料（rGO@MCSe），柔性三维分级结构氮掺杂碳纳米片/磷化钼纳米晶空心纳米球复合材料（MoP@C/N HCSs）等，并将它们作为碱金属离子电池电极材料。电化学测试显示所制备rGO@MCSe作为钠离子电池负极时，在10 A/g下具有311 mAh/g的高可逆比容量。得益于复合材料的高导电性和结构稳定性，rGO@MCSe电极表现出显著的赝电容电荷存储行为，极大地提高了其倍率性能和循环稳定性。进一步以铁基材料为底物，验证了硒化处理法在提升过渡金属基负极材料钠离子电化学存储性能的通用性。通过并通过各类非原位电化学和结构表征技术，探索了各种所制备的活性材料的结构与组成特征对电化学性能、储能机理、电极动力学的影响和科学规律，为开发高性能碱金属离子电化学存储奠定科学和物质基础。项目执行期间，共发表SCI论文5篇，申请专利1项，培养硕士毕业生4人，在读硕士生1人。