基于三维双相导锂复合固体电解质的高能量密度全固态锂电池的构建与相关机理

安全性好、能量密度高的全固态锂电池作为下一代储能体系的最佳候选者备受人们关注。但电极颗粒内部电子和离子导电性差、电极│电解质界面阻抗大，导致其循环性能差，限制了其应用。本项目提出一种先进的全固态锂电池构想——将高导电性的聚偏氟乙烯（PVDF）基复合固体电解质引入到正极层和电极│电解质界面，获得电极│电解质界面接触良好、正极层内部形成三维离子导电网络的全固态锂电池。将高锂离子导电性的硫化物电解质弥散在PVDF基电解质网络中，获得电化学性能稳定、与电极相容性强的三维双相导锂复合固体电解质；以经Li3PO4膜修饰的高振实密度5V级LiNi0.5Mn1.5O4和经Al2O3与石墨烯双重保护的LixSi为正负电极，构建高能量密度全固态锂电池。通过优化复合正负电极和复合固体电解质的构建工艺、探明复合固体电解质的复合机理及其在电极界面的作用机制，为高能量密度锂电池的设计和实用化提供实验依据和理论参考。

All-solid-state lithium battery (ASSLB) has attracted significant research attention as a promising candidate for next-generation energy storage systems owing to its high energy density and high safety. However, the inferior cycle performance of ASSLB resulted from the poor ionic and electronic conductivity in the electrodes,as well as the large interfacial resistance between electrode and electrolyte limit its commercial applications. Here, an advanced cell construction strategy has been proposed, in which poly(vinylidene fluoride) (PVDF) -based composite solid electrolyte with network structure and high conductivity is used both in cathode layer and interface of electrolyte│electrode, leading to an ASSLB with superior interfacial contact between electrolyte and electrodes, and forming a three-dimensional ionic conductive network in the cathode layer. The highly lithium ion conductive sulfide solid electrolyte is dispersed evenly in the matrix of PVDF-based polymer electrolyte to achieve a three-dimensional bicontinuous composite solid electrolyte with good electrochemical stability and excellent compatibility with electrodes. LiNi0.5Mn1.5O4 with high tap density coated with a Li3PO4 thin film and LixSi with double protection of Al2O3 thin film and Graphene are employed as cathode and anode to construct an ASSLB with high-energy-density. The production process of composite cathode, anode and composite solid electrolyte will be optimized and the reaction mechanism in the composite solid electrolyte and the action mechanism on the interfaces of the composite solid electrolyte and the electrodes will be investigated. The results of the study will provide an experimental basis and a theoretical reference for the design and practical application of ASSLB with high-energy-density.