三维多孔结构钒氧化物复合材料的设计合成及电化学性能研究

Lithium-ion battery is the main development trend of the portable energy. This project is aimed at the bottleneck of the lithium-ion battery: low energy density and back low temperature performance. We choose improve the energy and power density and widen the range of using temperature as the breakthrough points, focus on the synthesis of high performance vanadium oxide/carbon composite electrode materials and studying their microstructure control mechanism, which belongs to the cross research field of energy chemical engineering and materials science. The research contents include the formation mechanism of three-dimensional porous vanadium oxides, the formation process of the composite which contents of high conductive material and three-dimensional porous vanadium oxdies, the influence of microstructure on the electrochemical properties. In the theoretical level, we will study formation mechanism of the micro structure and the key physical chemistry properties of the corresponding material, provide original data and theoretical basis for further study,and reveal the influence of their microstructure on the energy density and power density of batteries. From a technical point of view, we obtain VOx/C composite materials with high conductivity through composite porsous vanadium oxides with a small amount of high conductive carbon in nano-scale, which could improve their electrochemical performance. On the other way, lower carbon black ratio is needed in the actual preparation of electrodes when the electrode materials are with high conductivity, which could further improve the volume energy density of batteries. The research results have important scientific significance and practical value on lithium-ion batteries used in electrical vehicle.

锂离子电池是便携式能源的主要发展方向。本项目针对锂离子电池的能量密度较低，低温性能差的发展瓶颈，以提高比能量比功率，拓宽使用温度范围为切入点，以钒氧化物/碳复合材料为研究对象，最终获得高能量密度且能在多温区正常使用的钒氧化物复合电极材料，属于能源化工和材料科学交叉的研究领域。研究内容包括三维多孔结构钒氧化物电极材料的微结构调控机理探索、高导电材料与三维多孔结构的钒氧化物复合过程的研究以及复合电极材料的微结构对电化学性能的影响研究。从理论层面上，系统研究VOx/C微结构的调控机理并对其中的物理化学关键技术进行研究，并揭示微结构对能量密度和功率密度的影响规律。从技术层面上，通过少量高导电的碳与多孔VOx纳米尺度的复合，获得具有高导电性的VOx/C复合材料，能降低在实际制备电极时加入的导电炭黑的比例，而进一步提高电池的体积能量密度。项目的研究成果将对电动汽车用锂电池具有重要的科学意义和实用价值。

本项目针对锂离子电池能量密度较低的发展瓶颈，以提高比能量比功率为切入点，选择钒基电极材料为研究对象，通过对钒基材料进行微结构设计，碳复合等工艺，最终获得高能量密度的钒基复合电极材料用于锂离子电池中。主要研究了水热法制备微米V2O5球/石墨烯复合电极材料，静电纺丝法制备多孔碳复合V2O5纳米管电极材料，冷冻干燥工艺结合热处理过程制备双重碳包覆磷酸钒钠电极材料，均获得了优异的电化学性能，此外我们研究了阵列电极的微结构进行调控，通过设计三维草状阵列结构，并分别进行表面聚合物包覆及引入高导电的Co单质，提高阵列结构的电子电导和结构稳定性，进而大幅度提升材料的大电流充放电性能，这些实验结果也可以为其它高体积变化的电极材料的结构提供解决思路。