自组装异价掺杂超薄二维纳米片增强储锂机理研究

It is one of the most challenging frontier researches to reveal the physical origin of electrochemical energy storage and degradation at atomic- and nano-scale in low-dimensional nanomaterials, and characterize unique surface, size,interface and their coupling effect on the energy storage of ultrathin two-dimensional (2D) nanomaterials in the field of condense matter physics, materials and electrochemistry. On the other hand, it is increasingly important to prepare single-crystalline ultrathin 2D nanomaterials with bigger planar size and higher conductivity on a scale via self-assembled approach due to their potential application in high-performance ultrathin flexible energy storage devices. In this project, we will develop novel self-assembled approach to the controlled preparation of ultrathin 2D nanomaterials together the improvement of intrinsic conductivity via heterovalent doping from the results of nonlayered structure ultrathin nanosheets. Meanwhile, we will also fabricate prototype device for the characterization of improved energy storage properties. Subsequently, we will develop new in-situ technique for the evaluation and characterization of electrochemical energy storage and degradation based on the combination of scanning probe microscopy and micro-Raman spectroscopy, and integrate the results of first-principle calculation and molecular dynamic simulation to establish theoretically analysis system in which the condense matter physics, materials and electrochemistry mutually cross and seep, thereby unveiling the physical mechanism of enhanced lithium storage of the ultrathin nanosheets with heterovalent doping at micro-meso-macro multiscale. We will strive for breakthrough in the in-situ characterization, theoretical analysis and physical mechanism of electrochemical energy storage in low-dimensional nanomaterials and our results are expected to provide scientific basis for the construction of novel ultrathin 2D nanomaterials and next-generation energy storage devices.

在纳米和原子尺度揭示低维纳米材料的电化学储能和失效机理，表征超薄二维纳米材料特有的表面、尺寸、界面及其耦合效应对储能性质的影响规律，是凝聚态物理、材料及电化学领域极具挑战的前沿课题之一。高性能超薄柔性储能器件方面的潜在应用使单晶面积更大、传导性能更好的超薄二维纳米材料的自组装规模化制备日益重要。本项目以非层状结构的超薄二维纳米片为研究对象，通过异价掺杂探索超薄二维纳米材料自组装可控合成新方法，改善其传导性能差的缺点，构筑高性能超薄柔性储能原型器件。基于扫描探针和微区拉曼技术组合发展电化学原位表征新技术，结合第一性原理计算和分子动力学模拟，建立凝聚态物理、材料和电化学的相互交叉渗透的理论分析体系, 从宏观-介观-微观多尺度揭示异价掺杂超薄二维纳米材料的增强储锂机理。力争在低维纳米材料储能性质的原位表征、理论分析及物理机制有所突破，最终为新型超薄二维纳米材料及储能器件的设计提供技术和理论依据。

在纳米和原子尺度揭示低维纳米结构的电化学储能和失效机理，探索低维纳米结构特有的掺杂、表面/界面、尺寸及其耦合效应对材料储能性质的影响规律和机制，是凝聚态物理、材料及电化学领域极具挑战的前沿课题之一。本项目以钛酸锂、磷酸钛钠、氮掺杂碳等材料为研究对象，发展纳米结构及其复合材料自组装可控合成的新方法和新技术，制备了一系列储锂/钠性能优良的超薄二维纳米片、介孔纳米晶及其纳米复合材料；结合CV/EIS/GITT、原位电化学/微区拉曼光谱以及计算模拟深入研究了这些纳米结构及其复合材料做为锂/钠离子电池负极的电化学性能，探索了掺杂、尺寸/表面效应、量子点修饰、高导电碳复合及其组合策略调控这些材料储锂/钠性能的规律和物理机制。在此基础上，以获得的高性能纳米复合材料为负极材料和活性炭、膨胀石墨、磷酸钒钠等为正极材料，构建了储能性能优良的锂/钠离子全电池、锂/钠离子混合电容器和钠双离子电池等原型储能器件。经过四年的研究，项目取得了较好的研究成果，部分结果已经以学术论文的形式在 Adv. Funct.Mater., J. Mater. Chem. A, J. Power Sources, Electrochim. Acta等期刊发表论文19篇；研究成果被国内外研究同行在Adv. Mater., Adv. Energy Mater., Adv. Funct. Mater., Small, Chem. Soc. Rev., Mater. Today等期刊引用200余次。研究结果为高性能锂/钠离子电池、锂/钠离子混合电容器、钠双离子电池等储能器件的研发积累了坚实的科学与技术储备。