正极氧化物/聚合物分子刷的多级序构化调控制备及其锂电高电压充放电性能提升机制研究

Nowadays, the layered transition metal oxide LiNi1-x-yCoxMnyO2 (abbreviated as LNCM，0≤x,y≤1) is one of the most widely applied cathode materials of lithium ion batteries (LIBs). However, while the LNCO has to be operated under high working voltage to elevate the energy density, the problems including inferior structural stability, rapid capacity attenuation, and increased polarization of electrodes, etc., restrict the realization and application of its high specific energy density. To address these issues, this project proposes the multi-scale regular construction of hierarchical structure assisted by polymer brushes on LNCM particle surface to enhance the cycling performance under high working voltage. Specifically, conducting the growth of polymer decoration unit, i.e. molecular brush on the surface of energy storage unit of LNCM, realizes the primary nanoscale structure firstly. Then followed with the ordered assembly and construction of conductive networks at the presence of conductive unit, the composite material with secondary microscale structure can be obtained, promoting the energy storage performance of LNCM-based composite when used as cathode in lithium-ion batteries. Moreover, the electrochemical tracking analyses and in-situ/ex-situ characterization will be conducted to research the electrode kinetics of composite cathode with hierarchical structure and the mechanism in which decoration unit affects the energy storage. This project can solve the application puzzles of oxide cathode which possessed high voltage and energy density, and provide new research ideas and scientific basis for the application of multi-scale regular and hierarchical structure in energy storage materials.

层状过渡金属氧化物LiNi1-x-yCoxMnyO2（LNCM，0≤x,y≤1）是目前应用最广泛的一类锂电正极材料。然而，为提升能量密度而在高电压下工作时，仍存在结构稳定性差、容量衰减快和极化增大等问题，限制了其更高比能的实现和应用。为了解决该问题，本项目提出在LNCM颗粒表面进行聚合物分子刷辅助的多级序构，来提升其高压循环性能，开发相应的高比能氧化物正极复合材料。具体地：首先在储能基元LNCM表面进行聚合物修饰基元的分子刷化生长，实现纳米尺度的一级序构，然后与导电基元进行有序化组装和导电网络构筑，获得具有微米尺度二级序构的复合材料，提升LNCM基复合正极的高比能储能性能。此外，还将进行原位/半原位表征和电化学跟踪研究，探明多级序构化复合正极的动力学特性和修饰/导电基元对储能性能提升的作用机制。有望解决氧化物正极的高比能化应用难题，为多级序构在储能材料中的应用提供新的研究思路和科学依据。

围绕二次电池电极材料相关的基础科学问题开展研究工作，本项目主要发展功能基元序构理念，研究了储能/修饰基元序构、自序构化碳纤维与储能基元二级序构以及储能/导电基元序构对电极材料性能的提升；通过精准的序构化制备获得了数个高性能电极材料，利用先进的材料（原位）表征和测量技术，并结合理论计算，深入研究了多基元多级序构对电极材料的电化学性能、反应机理、电极动力学和离子电子传输特性的影响规律，揭示了多基元多级序构对材料电化学性能提升的作用机理，阐明了储能基元、表面修饰基元和导电基元多级序构化与电化学性能之间的构效关系，为多级序构在储能材料中的应用、开发多级序构的高性能储能材料提供新的研究思路和科学依据。项目实施过程中，共发表了第一标注论文53篇，其中包括2篇Angew. Chem. Int. Ed.，1篇Adv. Mater.，4篇Adv. Funct. Mater.，2篇Sci. Bull.等；授权发明专利3项，新申请暂未授权发明专利3项；培养了毕业博士研究生1人，硕士研究生5人和博士后出站1人。