阵列结构高镍LiNi0.8Co0.1Mn0.1O2/OLO@Al2O3复合氧化物电极材料的可控制备、调控及储锂机制研究

Nickel-rich cathode materials like LiNi0.8Co0.1Mn0.1O2 (NCM811) possess the obvious advantage of high energy density, but the high concentration of Ni results in a high surface activity and a poor cycling performance, which could be enhanced with an effective coating strategy. Unfortunately, it is challenging to prepare target particles with homogeneous size distribution and desired morphology by conventional co-precipitation method. In this project, a uniform and regular precursor would be precisely synthesized via array-template method. The obtained nanosphere precursor will be used to controllable fabricate the array based nanosphere LiNi0.8Co0.1Mn0.1O2/OLO@Al2O3 composites by in situ coating with Li-Mn-rich cathode material and Al2O3 nanolayer. The purpose of this project is to study the structural design and the controlled synthesis of materials; the structural evolution and electrochemical mechanism of composites cathode; investigate the interface synergy effect among different compounds and storage energy mechanism. The influence of hydrodynamic performance on material morphology and chemical composition during reaction process, which are mainly determined by the momentum, heat and mass transfer and chemical reaction, will be systematically investigated. In addition, the dynamic simulation would based on the kinetic model would correspondingly be performed.

811型高镍三元材料具有能量密度高的优势，但镍含量过高导致其表面反应活性高，循环稳定性极差，须进行包覆改性。常规方法很难制备出形貌规则、粒径均一的三元材料颗粒，不利于后续形成均一、紧密的包覆层。本项目利用阵列材料形貌、粒径可控的优势，先制备出均匀、规则的纳米球阵列前驱体，再依次原位包覆富锂锰基材料和纳米Al2O3保护层，最后高温锂化反应，实现精准、可控制备阵列基纳米球LiNi0.8Co0.1Mn0.1O2/OLO@Al2O3复合氧化物材料，利用复合材料的协同效应改善高镍材料电化学性能。主要研究复合材料的结构设计和精准、可控制备；复合材料的结构变化和电化学反应机制。系统研究复合材料界面协同效应和储能机制；材料制备过程中反应体系流体力学特征材料形貌和化学组分选择性的影响，并建立动力学模型，进行动态模拟。

高镍三元正极材料是科技部、工信部等主推的高能量密度电池材料，也是我国新能源产业亟需解决的“卡脖子”技术。然而，高镍材料在应用过程中仍存在严重的表面副反应，微裂纹及结构退化等缺陷。本项目针对上述应用瓶颈，围绕材料结构多维精准调控这一关键科学问题，开展了材料前驱体可控制备、界面结构设计、一次颗粒尺寸与排列方式调控等一系列研究工作。主要研究内容包括：（1）采用氢氧化物共沉淀法制备了镍含量80%及以上的高镍前驱体，深入分析前驱体颗粒成核-生长机制，揭示了一次颗粒结晶过程，实现了前驱体可控制备；（2）揭示了高温过程中离子扩散机制，利用晶格掺杂、异质结构、表面包覆提升材料晶格与界面稳定性；（3）掺杂过渡金属位点，钉扎过渡金属层稳定氧，揭示高温晶面生长机制，调控晶面能量构筑径向有序结构，缓解颗粒体积应力抑制微裂纹生成，并揭示了晶面储能机理。这些成果为下一步开发超高镍（镍含量大于90%）正极材料奠定了坚实的基础。.项目执行期间发表重要学术论文58篇，申请专利4件，培养青年教师4人，硕博研究生32人、本科生19人，引进人才2人，选派人才出国4人，奖励荣誉6项，高端人才3项，并与企业合作建立示范基地1个、产线4条。