亚埃尺度下黑磷烯钠电池负极材料表界面结构演化的原位动态表征与储钠机制研究

The novel two-dimensional material phosphorene, which has a similar atom structure to graphene, is expected to be the ideal anode material for sodium-ion-battery because of its high theoretical storage capacity of 2596 mAh/g. However, the intrinsic mechanism of interfacial mass transfer and multiple phase change of phosphorene is still not understood completely because of the lack of direct experiment evidence. In this project, we use the spherical aberration correction transmission electron microscopy equipped with monochromator and in-situ electrical test system to trace the sodium ion diffusion pathway at the contact interface between phosphorene and the electrolyte and achieve the crystallographic analysis during charging/discharging processes. By using the high-resolution and ultrafast CCD camera in the transmission electron microscopy, we try to obtain the nature of the microstructure and phase evolution during sodiation/desodiation process in the sub-angstrom level, and further reveal the physical essence behind the dynamic electrochemical behavior. Combined with the imaging simulation and firs-principle calculation, the origin of the atomic structure and ion diffusion energy information of the two-dimensional layered structure evolution can be also explored. In the meantime, we can further deepen the complementary research of the phase evolution and the kinetics of sodium ions transport at the interface with the assistance of synchrotron radiation light source and three-dimensional tomography technology. And the study of the anode optimization of the phosphorene composite material is also developed. The work has significant theoretical and practical significance for promoting the development of phosphorene sodium-ion batteries.

新兴二维材料黑磷烯因其高达2596 mAh/g的理论容量有望成为大型储能钠离子电池的负极材料，然而对其表界面离子传质行为和相变机制仍缺乏全面认识。本项目采用配备单色器的球差校正透射电镜和原位电学测试平台，以黑磷烯表界面结构演变的动态表征为目标牵引，以期实现充放电时表界面钠离子传输通道的动态跟踪和晶体学解析；利用球差校正透射电镜的高分辨与超快CCD相机成像本领，尝试从亚埃尺度下认识嵌/脱钠过程中材料畴结构、相结构演化规律，并揭示其动力学行为和多重相变物理本质；结合相场(Phase-Field)模拟和DFT原理计算，探索黑磷烯二维层状结构演化的原子结构起源和表界面离子各向异性扩散的特定物理机制。同时，借助大型同步辐射光源技术和断层扫描三维重构透射电镜成像，进一步开展黑磷烯材料相变和表界面钠离子传输动力学过程的互补性研究，并优化黑磷烯复合电极材料，为黑磷烯钠电池的发展提供重要技术储备和理论依据。

根据项目申报书的研究计划，本项目已经采用配备单色器的球差校正透射电镜和原位电学测试平台，以黑磷烯表界面结构演变的动态表征为目标牵引，完成了充放电时表界面钠离子传输通道的动态跟踪和晶体学解析；利用球差校正透射电镜的高分辨与超快CCD相机成像本领，从亚埃尺度下认识到嵌/脱钠过程中材料畴结构、相结构演化规律，揭示了其动力学行为和多重相变物理本质；通过大量精细的原位动态表征实验工作，已获悉黑磷烯二维层状结构演化的原子结构起源和表界面离子各向异性扩散的特定物理机制，为黑磷烯钠电池的发展提供重要技术储备和理论依据。同时，借助研究黑磷烯原位TEM充放电的经验积累和本项目的资助，陆续开展了其他相关材料的储能机制研究并取得了一定的科研成果。总体而言，本项目已经顺利完成了预定的研究计划。