高剪切与金属掺杂联合调控连续制备磷酸铁锂/碳的过程基础

This application focuses on the preparation of high performance Li1-xMxFe1-yNyPO4/C with the goal of lower the cost. First of all, the micro-mixing and transfer characteristic in liquid-solid-solid multiple system of high shear mixer will be studied; the amplified model of the flowing and transfer in the reactor will be set up to provide a support for the design and optimization of the reactor. Furthermore, combined with the characterizations of the electrochemical performance, the key factors that regulated the crystal structure, morphology, metal ion doping of LiFePO4 under the high shear mixer will be studied as well. In the meanwhile, it will be essential to explore the transformation of molecule structure during the carbonization under high shear mixer and the adjusting method for carbon coating on the surface of Li1-xMxFe1-yNyPO4/C. Finally, the technology and the equipment during the continuous hydrothermal synthesis of Li1-xMxFe1-yNyPO4/C will be optimized in order to solve the problem of high production cost and batch unstable, which will provide a foundation for the achievement of the low-cost and scale-up preparation of Li1-xMxFe1-yNyPO4/C. This investigative achievement may provide new research ideas and methods for the regulation of crystal structure, morphology and composition during the liquid-solid-solid multiphase system; and also has important guiding significance and practical value for the investigation and application of the multiphase process intensification technology.

本申请以实现高性能Li1-xMxFe1-yNyPO4/C的低成本制备为目标，首先，研究液-固-固多相体系高剪切反应器微观混合与传递特性，建立描述该反应器流动与传递的放大模型，为反应器的优化与设计提供工具；进而，结合充放电性能表征，研究高剪切强化反应中调节LiFePO4晶体结构、形貌、金属原子掺杂的关键；同时，研究高剪切下糖焦化过程的分子结构转变以及Li1-xMxFe1-yNyPO4表面碳包覆层的调控方法；最后，对高剪切强化合成Li1-xMxFe1-yNyPO4/C连续化制备过程进行工艺与设备优化，解决现有工艺生产成本高、不同批次产品不稳定的问题，为实现高性能Li1-xMxFe1-yNyPO4/C材料的低成本、大规模制备奠定坚实基础。本项目的研究成果可以为液-固-固多相体系中晶体结构、形貌、组成的调控提供新思路与新研究手段；对于多相过程强化技术的研究与应用具有重要的指导意义和实用价值。

本项目对高剪切混合器的几何构型进行了优化研究，降低了功耗、提高了混合与传递性能；研究了非化学计量比、金属掺杂对磷酸铁锂电化学性能的影响规律，获得了高剪切和金属掺杂对水热合成 Li1-xMxFe1-yNyPO4 /C 的晶体结构与形貌、糖焦化形成碳包覆层的调控关键。研究了碳包覆层的N、B、P改性提高碳层导电性的影响规律和萘造孔调控碳层孔结构改善锂离子传递性能的方法，进而形成了调控表面碳层改善Li1-xMxFe1-yNyPO4 /C电化学性能的方法。采用金属有机框架、原位聚合酚醛树脂等合成了磷酸铁锂三维碳复合材料，获得了高稳定的Li1-xMxFe1-yNyPO4 /C材料。此外，还进行了高安全丁二腈基电解液、高电压正极材料NCM523的研究。利用本项目的研究成果制备的LiFePO4 /C材料，在20C倍率下，其容量达到了120mAh g-1左右，在500个充电-放电循环后其容量保持率达82%以上。本项目发表国际期刊论文13篇，申请了中国发明专利5件（其中获批4件），培养了研究生10人。.本项目的研究成果，突破了现有工艺生产成本高、不同批次产品不稳定的技术瓶颈，为实现高性能Li1-xMxFe1-yNyPO4 /C 材料的低成本制备奠定了坚实基础；还为液-固-固多相体系中晶体结构、形貌、组成的调控提供新思路；对于多相过程强化技术的研究与应用具有重要的指导意义。