有机无机复合固体电解质在高能量密度和高安全性电池中的应用

To meet the requirements of high energy density, safety and long cycle life, it is necessary to replace the organic flammable electrolyte and graphite anode of the Li-ion battery by a solid electrolyte and metallic-lithium anode that can be plated/stripped reversibly without dendrites formation. However, dry Li+ polymer electrolyte usually present poor ionic conductivity at solid state, weak mechanical properties if it is made to be a free standing membrane with a thickness similar to traditional polypropylene separator. Many inorganic ceramic or glass electrolytes may have high mechanical strength and show comparatively high conductivity, but suffer from inflexible interface problems, including high interface resistance and severe dendrite growth owing to an non-uniform contact and surface grain boundaries on interface, those are inherent with solid ceramic electrolytes. This situation has motivated attempts to develop the inorganic/organic composite electrolyte, which not only gives a uniform Li+ flux across the interface and dramatically lowers the interface resistance, but also successfully suppresses unwanted dendrite formation and therefore results in a good cycling performance and high efficiency of all-solid-state cells. In this proposal, we will first try to develop different kinds of high voltage stable, high ionic conductivity at room temperature polymer electrolyte and single Li ion conducting polymers. Combined with the modification of inorganic electrolyte particle or pellet surface, inorganic/organic composite electrolyte will be prepared and investigated in the all-solid-state batteries. With the comparison of electrochemical performance, further optimization on the polymer structure, Li ions – ligand interaction, inorganic electrolyte surface and interface processing will be carried out to reach the extremely safe all–solid–state lithium cells.

全固态锂离子电池由于其远高于传统电池的的安全性，并且可以使用锂金属负极从而大大提供能量密度，而被视为下一代最重要的储能技术之一。根据固态电解质的组成，全固态锂离子电池可以分为无机固态电解质电池和聚合物电池。尽管有明显的优势，其实用化还有很多挑战：聚合物电解质机械性能差，常温下导离子率低，无机陶瓷/玻璃电解质与金属锂之间接触不均匀，界面电阻大。鉴于有机、无机固体电解质各自的优缺点，运用有机无机复合固体电解质材料，可以使无机电解质和电极之间紧密粘接，界面处的锂离子流更加均匀，不仅降低了界面电阻，同时避免了界面双电层电场，有效缓解锂枝晶的形成，从而提高电池的循环寿命。本项目中将设计合成高电压稳定、室温下导离子率高的聚合物电解质以及单离子导体型聚合物，并通过优化无机陶瓷类电解质的表面结构，构建有机/无机复合电解质。优化两者间的组合及界面处理工艺，研发高导离子率的复合固体电解质及相应的全固态电池。

近年来，申请人对全固态电池进行了系统的研究工作，包括固体电解质的设计和制备以及固体电解质与固体电极之间的界面调节。1）申请人提出了“多层复合固体电解质”的设计概念，如聚合物/陶瓷、聚合物/聚合物、陶瓷/陶瓷多层固体电解质。这些多层结构不仅改善了固体电解质与电极之间的界面接触，而且拓宽了整个电解质系统的电压窗口。2）开发了一种新型高电压稳定的聚合物固态电解质——聚草酸酯。3）开发了一种以低成本制备单晶高镍氧化物正极的新方法，该方法已在巴斯夫的中试生产中进行。在该项目的支持下，申请人以第一作者和通讯作者的身份发表了20多篇论文，其中包括Angew Chem. Int. Ed. (6)， Adv. Mater.(1)，Adv. Energy Mater.(2)，Adv. Funct. Mater.(4)等。申请人后续将继续开展全固态锂电池关键材料和界面调节的基础研究，为高安全、长寿命固态储能提供可行的解决方案。