多孔分级微纳结构LiAlO2快离子导体改性LiMnPO4/C正极材料的研究

LiMnPO4 shows great potential in the lithium-ion battery due to higher operating voltage (4.1V vs. Li+/Li), safety, environmental protection, low-cost and high theoretical capacity. The poor conductivity and electrochemical performance limit its application. Aluminum web-based anodic aluminum oxide (AAO) as the template was cleverly constructed fast ion conductor LiAlO2 with porous multi-level micro-and nano- structure by in-situ hydrothermal method, and then, LiMnPO4 was deposited and crystallined in the hole by the sol-soak method and the ionic liquid electrodeposition method. By adjusting the process parameters of the various preparation techniques,adjusting the process parameters to achieve the two-phase nanostructur composite was achieved and the LiMnPO4/C-LiAlO2 nanocomposites was prepared. On the one hand, using the LiAlO2 fast ion conductivity, and doping process in the formation of the Mn2+/Al3+ part of each other doping improve the conductivity of the material,on the other hand, superior electron conductive properties of the nano-carbon improve the comprehensive performance of the composite material.By studying the variation of lithium ion conductivity in electrode caused by porous multi-level micro- and nano-structure of two-phase with different lithium ion conductivity, it is clarified to the mechanism of action of the LiAlO2 doped LiMnPO4/C, and it is trying to establish a theoretical framework to describe the quantitative relationship of two-phase microstructure and performance, which will provide new ideas for the modification and development of cathode materials for lithium-ion battery.

LiMnPO4具有安全环保、成本低、理论容量高、4.1V 的稳定工作电压平台等优点，在锂离子动力电池中表现出很大潜力。但由于导电性极差，电化学性能不理想，限制了其应用。本研究以铝网基AAO为多孔分级微纳结构模板，巧妙地原位水热法构建多级微纳结构LiAlO2锂快离子导体，以此通过溶胶浸泡法和离子液体辅助电沉积法在孔中沉积LiMnPO4，调整工艺参数，实现两相复合，制备出LiMnPO4/C-LiAlO2纳米复合材料。一方面利用LiAlO2快离子导电性，以及掺杂过程中形成的Mn2+/Al3+部分相互掺杂来提高材料的导电性；另一方面利用纳米碳优异的电子导电性能改善复合材料的综合性能。通过对锂离子电导率迥异的两相多级微纳复合结构与性能的研究，阐明LiAlO2掺杂LiMnPO4/C的作用机理，建立描述两相显微结构与性能定量关系的理论框架，为锂离子动力电池正极材料的改性与发展提供新的思路。

LiMnPO4具有安全环保、成本低、理论容量高、4.1V 的稳定工作电压平台等优点，在锂离子动力电池中表现出很大潜力。但由于导电性极差，电化学性能不理想，限制了其应用。本研究以铝网基AAO为多孔分级微纳结构模板，巧妙地原位水热法构建多级微纳结构LiAlO2锂快离子导体，以此通过溶胶浸泡法和离子液体辅助电沉积法在孔中沉积LiMnPO4，调整工艺参数，实现两相复合，制备出 LiMnPO4/C-LiAlO2 纳米复合材料。结果表明：当与6%质量分数的LiAlO2复合时，取得了较高的放电容量，在0.05C倍率下，放电容量达到142.8 mAh/g，50圈循环后容量衰减94.8%。阻抗结果显示，此时的锂离子扩散系数为2.07x10-14 cm2/s。当在LiAlO2模板中沉积LiMnPO4时，制备的3D电极取得了在10C下循环100圈容量衰减率为98.4%，容量保持在105 mAh/g的优异性能。同时也第一次通过离子液体电沉积法合成了LiMnPO4。通过对锂离子电导率迥异的两相多级微纳复合结构与性能的研究，阐明 LiAlO2掺杂LiMnPO4/C的作用机理，为锂离子动力电池正极材料的改性与发展提供新的思路。