基于LiNi0.5Mn1.5O4的高功率型电极材料的制备及电化学性能研究

There is increased demand for lithium ion batteries with better performance for higher power densities and voltage in recent years. The improvement of rate capabilities for LiNi0.5Mn1.5O4-based cathode materials with high operating potential (4.7 V vs. Li/Li+) is of great importance for power battery applications. In this proposal, porous LiNi0.5Mn1.5O4 materials with nano-micro structure will be prepared by a novel method using supporting bodies of MnO2 and Mn2O3 as the force center for thermal decomposition, which is good for the improvement of distribution uniformity of hole structure, the improvement of mixing degree among different transition metal ions and the enlargement of the specific surface area of LiNi0.5Mn1.5O4 materials. Then, porous LiNi0.5Mn1.5O4 materials will be coated and permeated by Co3O4 deposition layer, with the mechanism that stable [Co(NH3)6]3+ ions could be decomposed to form Co3O4 materials at elevated temperature. This coating technology is easy to control. After that, a new efficient conductive network will be built linking carbon nanofiber and LiNi0.5Mn1.5O4/Co3O4. Advantages, disadvantages as well as mechanisms will be clearfied by the studying of effects of these modification methods on performances of cells’ power capabilities and discharge plateaus. It is possible that the implementation of this proposed project will not only build correlations and relational models among modification methods and technological conditions, electrode’s performances and cell’ power properties, but also provide a useful theoretical guidance for preparation, modification and property prediction of similar materials.

提高具有4.7 V 放电平台的LiNi0.5Mn1.5O4的大倍率性能，可实现锂离子电池正极材料的高功率密度化。首先，项目拟利用MnO2、Mn2O3等支撑体作为热分解的受力中心来制备纳微结构的多孔LiNi0.5Mn1.5O4，方法有利于提高孔道的分布均匀性，元素间的混合程度及产品的比表面积。然后，拟利用 [Co(NH3)6]3+自身强的稳定性及在加热条件下可分解的特性，实现Co3O4对多孔LiNi0.5Mn1.5O4内空隙的高效包覆及扩渗，方法可调控性高。在此基础上，搭建起碳纳米纤维与LiNi0.5Mn1.5O4/Co3O4间的新型高效导电网络。通过分析比较不同改性手段在提高电池倍率性能及工作电压等方面所发挥的具体作用及各自存在的优缺点，明确不同改性手段的有效性原理，建立改性措施及工艺条件——电极材料各项性质——电池功率性能间的相互关联，为类似物质的制备、改性及性能预测提供指导。

项目通过提高具有4.7V放电平台的LiNi0.5Mn1.5O4大倍率性能，进而实现了锂离子电池正极材料的高功率密度化这一研究目标。首先以自有专利技术制备出了孔道分布均匀的、具有纳微结构的多孔LiNi0.5Mn1.5O4，然后采用新型包覆技术对多孔LiNi0.5Mn1.5O4内空隙进行了高效包覆及扩渗，最后搭建起了碳纳米纤维与改性LiNi0.5Mn1.5O4间的新型高效导电网络。通过分析比较不同改性手段在提高电池倍率性能及工作电压等方面所发挥的具体作用及各自存在的优缺点，明确了不同改性手段的有效性原理，建立起了改性措施及工艺条件——电极材料各项性质——电池功率性能间的相互关联，为类似物质的制备、改性及性能预测提供了指导。项目实施期间中，已在Electrochimica Acta、Journal of Alloys and Compounds等期刊发表SCI论文9篇，申报发明专利4件，参加国内外学术会议27人次，并培养硕士研究生4名。