高功率锂氟化碳电池正极材料及界面性质研究

Li/CFx battery possesses the highest energy density among all primary lithium batteries with a theoretical value of 2180 Wh/kg, presenting several advantages of high and flat discharge potential (about 2.5-2.8 V), large temperature range of use (from -40 DEC to 170DEC), long shelf life (7-10 years), and so on. However, the battery is known to suffer from kinetic problems due to the cathode material CFx is intrinsically a poor electronic conductor, inhibiting its application in high-power devices. Aiming at the conducting and energy storage properties of CFx material, a hierarchical "microparticle size- nanostructure" approach is proposed, in order to prepare the high power density CFx materials without compromising their high energy density. And the material design and preparation methods, the components, structure, and morphology of the materials related to the electrochemical performances will be investigated. Furthermore, the properties of the CFx cathode/electrolyte and CFx composite layer/current collector interfaces will be studied. And the new electrolytes and new current collectors will be prepared to improve the interface performances. In addition, the electrode swelling and voltage delays will be investigated and abated. Aiming at elevating the power density of CFx battery without compromising its high energy density, this programme will provide new ideas and approaches for CFx battery application.

锂/氟化碳一次电池具有高理论质量比能量（约2180Wh/Kg），使用温度范围广，搁置寿命长，安全性好等优异特性。但是由于正极材料氟化碳本征的导电性差、电极动力学过程缓慢导致了锂/氟化碳电池在放电过程中产生较大的极化，使锂/氟化碳电池仅限制在低倍率下放电场合。针对氟化碳材料的导电机制及能量存储特点，采用"微米尺度-纳米结构"的分级设计思想，借鉴天然物质结构，探索材料设计及制备。深入研究材料的组成、结构、形貌对电化学性能影响，制备出兼具功率密度及能量密度的氟化碳电极材料。进一步，引入新型电解质和新型集流体，深入研究及改善氟化碳电极/新型电解液界面，氟化碳复合层极/集流体界面。同时，在研究过程中逐渐认识与改善电压滞后，电极膨胀等缺点。本项目旨在提高锂/氟化碳电池的功率密度，同时兼顾能量密度。为高功率氟化碳电池的应用提供了新理论依据及新方法。

本项目计划研究采用“微米尺度-纳米结构”的分级设计思想，制备出兼具功率密度及能量密度的氟化碳电极材料，并研究材料的组成、结构、形貌对电化学性能影响，研究并改善电极界面。本项目完成了采用不同氟化碳材料作为前驱体，对其表面进行改性修饰，形成氟元素梯度材料，有效改善材料表面的电子电导率，提高氟化碳材料的倍率特性。系统的研究了电极与电解液之间的界面电化学性能，探讨主盐、溶剂、电解液添加剂对体系电化学性能的影响。并合成一种氟化有机酯类化合物C5H11F2O3，有效提高锂氟化碳电池在高温下的倍率特性。通过流体自组装、自粘合方式制备的石墨烯纸及石墨烯纸复合材料集流体，有效地加快电极反应的动力学过程，减小了正极膨胀带来的刚性应力，增强界面结合力，从而在保证体系能量密度的前提下，大大提高体系的功率密度。从氟化碳材料设计与制备、集流体/电极界面、电解液/电极界面等方面的深入研究，为研制兼具能量密度和功率密度锂氟化碳电池打下坚实的理论基础并积累了丰富的实践经验。本项目开展过程中共发表SEI论文23篇，EI论文1篇，专利3篇，其中授权1篇。