双连续复合结构半中空石墨烯卷包覆钒氧化物纳米线器件组装、储锂性能与机理

Lithium-ion batteries based on semi-hollow graphene nanoscroll coated vanadium oxide nanowires with bi-continuous hybrid structure with high performance, integration, low cost and free-pollution is advanced and crossed area of new-energy technique and nanotechnology. This proposal focuses on the design of bi-continuous conducting network and preparation of graphene/vanadium oxide nanowires by template method, wet chemistry method, electrochemical method and so on, which can be used for the assembly of single nanowire device and the cathode materials of lithium-ion battery. The characterization of the products, such as phase, morphology, interfacial structure, coated method, spectral feature will be conducted. Further the relationship between the material structure, length, diameter, surface oxygen atom defects pH value and Li ion distribution, electron transport, electrochemical polarization, charge/discharge, cycling reversibility will be investigated. Consequently, the intrinsic relationship between chemical bond distortion, electron distribution changes and electron transport efficiency during the reaction process will be revealed. To improve the intercalation/disintercalation process, the approaches will be adopted by controlled synthesis of material, composite construction, even coated construction , performance control, then the results will be optimized by genetic algorithm. This research will lay a foundation for the investigation and application of new type composite nanowire lithium-ion battery.

开发基于双连续复合结构半中空石墨烯包覆纳米线材料的高性能、复合化、低成本、绿色化的锂离子电池是新能源技术和纳米技术的交叉和前沿。本项目拟基于双连续导电网络设计，结合模板法、湿化学法、静电纺丝法等制备石墨烯/钒氧化物纳米线，并以此组装单根纳米线器件和锂离子电池。表征复合结构纳米线的物相、形貌、界面结构、包覆方式、光谱特征等，原位测试复合结构纳米线的电输运与本征电化学性能。研究材料结构、长度、径宽、表面氧原子缺陷、pH值等因素与锂离子扩散、电子传输、极化、充放电、循环可逆性等的相互关系，揭示反应过程中化学键畸变、电子分布变化与电子输运效率、锂离子电池容量的内在联系。通过材料的可控生长、复合构筑、均匀包覆、性能调控等提高纳米线的脱嵌锂性能，并采用遗传算法对结果进行优化，为新型复合纳米线锂离子电池正极材料的探索与开发奠定科学基础。

通过相分离策略、自组装方法和梯度静电纺丝技术成功地实现了钒氧化物基纳米线的制备及有序组装，其独特的形貌结构为高效电化学储能提供了双连续的电子／离子通道、大的固液接触面积及应力弛豫空间。并成功实现了碱金属离子预嵌入对纳米材料电化学性能的优化，发现合适的金属离子能有效扩大层状材料的层间距，因此达到优化的循环性能和倍率性能的目的。探索了钒氧化物基纳米线在不同的电化学反应电位下的结构演化，通过原位表征建立了纳米线的电输运、结构与电极充放电状态之间的直接联系，揭示了纳米线的本征电化学行为及锂／钠离子电池容量衰减的本质。项目研究成果为纳米高性能储能电池的研制与开发提供科学依据。