基于石榴石型固态电解质的全固态锂硫电池

Lithium-sulfur batteries have a higher energy density, but it has two important issues, shuttle effect and the formation of lithium Dendrite on the negative electrode. All-solid-state battery to completely solve these two problems, and to further improve the energy density and safety. This proposal aims to prepare all-solid-state lithium-sulfur batteries with high energy density, long cycle life based on Garnet-type solid electrolyte. Li2S nano-particle with graphene coating, which will increase the electrode conductivity, can be used as cathode material. Through the optimization of nano-particle size and the synthesis method of Li2S compound with lithium-ion conductor, the electrode material will at the same time have both strong ionic and electronic conductivity. Using this electrode, we will demonstrate a novel Lithium-sulfur battery based on a tri-layer structure, with one dense layer and two porous layer. Sulfur electrode material and lithium will all be filled into the porous structure of tri-layer electrolyte. This can efficiently increase the contact surface area and decrease the resistance between electrode and solid electrolyte. At last, we will focus on the study of a variety of factors that will influence the capacity and performance of all-solid-state lithium-sulfur batteries and optimize the experimental method and improve the electrochemical performance of all-solid-state lithium-sulfur battery.

锂硫电池有很高的能量密度，但是，它有两个最重要的问题，穿梭效应及锂负极枝晶生长。全固态电池能够彻底的解决这两个问题，并且能进一步提高能量密度和安全性。本项目拟制备基于石榴石型固态电解质具有高能量密度、长循环寿命的全固态锂硫电池。我们将使用石墨烯对Li2S纳米粒子进行包覆，提高电极导电性。通过优化Li2S纳米粒子大小及其与锂离子导体复合的方法，使电极同时具备良好的离子及电子导率。通过制备具有两面多孔层，中间致密层的三层结构固体电解质，将正极材料及锂金属分别填充进多孔固态电解质内，增大电极材料与电解质间的接触面积，降低接触电阻。同时，我们将深入研究全固态锂硫电池中影响电池容量及循环性能的各种因素，进一步优化实验方案，提高电池性能。

固态电池具有高安全性，高能量密度，被认为是继锂离子电池之后下一代电池。特别是对于固态锂硫电池，更是得到了广泛的关注。固态锂硫电池不仅可以实现高能量密度，并且能够从根本上解决锂硫电池的穿梭效应。石榴石型固态电解质因其高的室温电导率及对锂稳定等特性，非常有潜力应用于固态电池制备。本课题研究了基于石榴石固态电解质的全固态锂硫电池。1.分别使用流延法和固相烧结法制备了石榴石固态电解质。通过在氧气环境下进行固态电解质烧结，简单高效的制备得到了高致密度的石榴石固态电解质。2.使用柠檬酸溶液对石榴石固态电解质进行处理，简单有效的除掉了电解质表面的碳酸锂，从而显著增强了石榴石固态电解质与锂金属之间的界面接触。3.石墨烯可以具有吸附微波特性，通过微波辅助，可以帮助硫在40秒内快速均匀地沉积在石墨烯表面。从而制备得到高质量的石墨烯/硫复合电极材料。4.通过原位固化法组装了全固态锂硫电池，20次循环后仍能保持接近1000 mAh/g的容量。