具有结构支撑效应的新型钒基锂离子电池正极材料的研究

Vanadium-based compounds have been widely studied as cathodes for lithium-ion batteries since they have several intrinsic advantages, such as high specific capacity, excellent conductivity and low cost. However, most vanadium-based compounds endure bad cycle performance, because their layered structures collapse during the frequent lithium ion intercalation and de-intercalation process. In this project, we intend to research the layered structures of vanadium-based compounds by understanding the crystal structural characteristics and electrochemical properties. Accordingly, an appropriate structural element is introduced into the structural framework to connect the adjacent layers together, which may be described as the “pillar effect”. The novel optimized vanadium-based electrode materials with structural “pillar effect” should be comparatively rigid against lithium insertion and extraction. The “bottom-up” route on the basis of “nanosheets re-assembly” process and the “top-down” route on the basis of “conductive polymer intercalation” process will be developed to obtain layered Li/Ag/Cu-V-Oxide lamellar structures and nano-structural PANI - VOx/ LiV3O8 composite electrodes, respectively. These novel materials will be further studied by examining the relationships between its structure and electrochemical performance. Our investigation of this project will be helpful to expand the vanadium compound cathode materials systems with optimum structure to suppress the structural destruction, as a result, the improvement of cyclic stability.

钒基化合物作为锂离子电池正极材料具有比容量高、导电性好、价格低廉等优点，但大多数钒基化合物电池循环性能并不理想，这是由于锂离子频繁的嵌入和脱嵌导致其层状结构塌陷。本项目拟以钒基化合物层状结构为主要研究对象，以钒基化合物设计的晶体结构和电化学性能为研究主线，提出在钒基化合物相邻钒氧层之间引入起支撑作用的结构单元，获得兼具二维结构和结构支撑作用双重特点的新型钒基化合物正极材料。这种“支撑效应”将有效抑制充放电过程中存在的层状结构塌陷，提高电池的循环稳定性。本项目拟通过“自下而上”的“纳米片再组装”策略和“自上而下”的“导电聚合物插层”策略，获得层状Li/Ag/Cu-V-Oxide无序纳米片堆积材料和PANI-VOx/LiV3O8纳米复合材料，揭示其结构与电化学储锂性能的相关性。本项目的研究成果将为拓展钒基化合物正极材料体系以及解决层状电极材料结构塌陷、提高电池稳定提供了新的理论和研究思路。

锂离子电池广泛应用于便携式电子设备，同时也是新一代混合动力汽车与纯电动汽车的能源系统的理想之选。但电极材料的性能始终影响和制约着锂离子电池的容量和寿命。因此我们选择具有比容量高、导电性好、价格低廉等优点的钒基化合物作为锂离子电池正极材料，很有可能满足新能源电动汽车电源高能量和大功率密度的需求。本项目以钒基化合物层状结构为主要研究对象，系统合成和研究了钒基化合物主要包括氧化钒和钒酸盐的结构、形貌与和电化学性能之间的关系，揭示其结构与电化学储锂性能的相关性。在本基金项目的支持下，发表SCI论文6篇，申请发明专利5项，培养研究生6名，初步建立了一支结构合理，开拓进取的科研队伍，按计划完成了预期目标。本项目的研究成果必将为拓展钒基化合物正极材料体系以及解决层状电极材料结构塌陷、提高电池稳定提供了新的理论和研究思路。