多次共沉淀-二步焙烧法制备高性能多重核壳结构富锂锰基正极材料的研究

According to the characteristic of LiNi0.8Co0.1Mn0.1O2 and Li2MnO3, a new layered (1-x)LiNi0.8Co0.1Mn0.1O2@xLi2MnO3 material with multiple core-shell structure, where LiNi0.8Co0.1Mn0.1O2 is used as the core and Li2MnO3 is used as shells, is designed as cathode material with high capacity, high safety, good cyclability and excellent rate capability for lithium ion batteries. In the multiple core-shell structure, the concentration of the core and shell change oppositely in a certain arithmetic progression，i.e., from the centre of core to the surface of the shell, the concentration of the core decreases in the arithmetic progression, while the concentration of the shell increases in the same arithmetic progression. The concentration of metal ion in different shell is kept to ensure the composition of the core and the shell change continuously and eliminate the structural mutation between the core and the shell, and then decrease the impedance between different phases and improve the performance of materials. A multi-steps coprecipitation-secondary sintering technique is explored to carry out the controllable synthesis of (1-x)LiNi0.8Co0.1Mn0.1O2@xLi2MnO3 by optimizing the synthesis technique, designing core and shell materials, and controlling difference in composition between different layers of core-shell structure. The working mechanism of sintering way on the information and development of the core-shell structure will be studied, and the effects of core-shell structure on the charge-discharge reaction, cycling stability and thermal stability will be investigated in detail, and the conductivity properties of lithium ion and electron in core-shell structured materials and interface between electrode and electrolyte will be clarified, and then the performance modification mechanism of core-shell structure will be revealed. The project will provide new ways for designing cathode materials in lithium ion batteries and establish theoretical and experimental base for application of Li-rich Mn-based materials.

本项目设计了一种以LiNi0.8Co0.1Mn0.1O2为核、以Li2MnO3为壳的多重核壳结构层状富锂锰基材料，以期得到容量高、安全性高、循环稳定性好、倍率性能优良的锂离子电池正极材料。在这种结构中，核与壳的浓度按照一定的等差数列呈反梯度变化，即由核心至外壳，核材料浓度呈递减等差数列分布，壳材料呈递加等差数列分布。设计时保证各壳层的过渡金属离子浓度一样，保证核材料与壳材料之间成分连续变化，消除结构突变，以尽可能减小材料间的相界电阻，提高材料的性能。采用多次共沉淀-二步焙烧法实现材料的可控合成，研究焙烧制度对核壳结构形成的作用机制，查明核壳结构对材料充放电反应、循环稳定性和热稳定性的影响规律，理清材料体相以及材料/电解质界面的锂离子/电子传导特性，最终揭示核壳结构提高材料性能的机理。本项目的实施，将为锂离子电池材料的设计提供新思路，为富锂锰基正极材料的实用化提供理论和实验依据。

本项目设计了一种以 LiNi0.8Co0.1Mn0.1O2 为核、以 Li2MnO3 为壳的多重核壳结构层状富锂锰基材料，以期得到容量高、安全性高、循环稳定性好、倍率性能优良的锂离子电池正极材料。在这种结构中，核与壳的浓度按照一定的等差数列呈反梯度变化，即由核心至外壳，核材料浓度呈递减等差数列分布，壳材料呈递加等差数列分布。设计时保证各壳层的过渡金属离子浓度一样，保证核材料与壳材料之间成分连续变化，消除结构突变，以尽可能减小材料间的相界电阻，提高材料的性能。采用多次共沉淀-二步焙烧法实现材料的可控合成，研究焙烧制度对核壳结构形成的作用机制，查明核壳结构对材料充放电反应、循环稳定性和热稳定性的影响规律，理清材料体相以及材料/电解质界面的锂离子/电子传导特性，最终揭示核壳结构提高材料性能的机理。本项目的实施，将为锂离子电池材料的设计提供新思路，为富锂锰基正极材料的实用化提供理论和实验依据。在本项目的资助下，项目组获得了如下研究成果：（1）在《Journal of Power Sources》、《Advanced Powder Technology》、《Ionics》、《Journal of  Materials Chemistry A》、《Applied Surface Science》、《Vacuum》、《Ceramics International》、《Microchimica Acta》、《Frontiers in Chemistry》、《International Journal of Electrochemical Science》、《中国有色金属学报》、《环境工程学报》、《精细化工》等刊物上发表了36篇，其中会议论文11篇，被SCI收录14篇、EI收录18篇、CSCD核心期刊论文8篇。（2）申请国家专利3项，其中获得授权国家发明专利何实用新型专利各1项；（3） 培养中青年骨干教师4名、培养或正在培养硕士研究生7名。