金属锂表面有机无机杂化膜的构建及电化学性能研究

With the development of portable electronic devices and electric cars, high-energy density rechargeable batteries are the hotspot. Lithium metal is an ideal anode material for high-energy rechargeable batteries due to its high theoretical energy density (3860 mAh/g) and the lowest negative electrochemical potential (3.04 V vs the standard hydrogen electrode). But uncontrollable dendritic Li growth and limited Coulombic efficiency during Li deposition and stripping inherent in these batteries have prevented their practical applications in lithium metal batteries. Dendritic Li will result in the poor safety performance and short cycling life. Depending on the recent researches, the modification of SEI to inhibit the growth of lithium dendrite is a more controllable and efficient way. In this project, the authors will modify an artificial SEI film on the surface of lithium metal to restrain the growth of dendritic lithium. The artificial SEI film compounded by organic materials and inorganic polymers, it has both the toughness inorganic materials and the strength of organic materials and has a high ionic conductivity. Through the battery test, morphology and structure characterization, and in situ optical microscope,SEM and TEM observation. Systematically study the effects and roles of the organic-inorganic hybrid membranes on the suppression of dendrite. With the continuously improvement, finally realizes the inhibition of lithium dendrite growth and the improvement of safety concern and cycle performance of lithium metal anode. Our work will provide theoretical guidance and technical support for the application of metallic lithium in the next generation of high-energy density batteries.

随着便携式电子设备和电动汽车高速发展，高能量密度的可充放电电池成为研究热点。金属锂由于其具有高理论能量密度（3860 mAh/g）和低负极电位（-3.04V vs SHE）而备受关注。然而金属锂在溶解沉积过程中存在锂枝晶不可控生长，导致电池的安全性能差、循环寿命短，制约了其在金属锂电池中的发展和应用。研究表明，通过改性SEI膜抑制锂枝晶生长是较为可控和高效的方法。本项目拟在金属锂表面修饰人工SEI膜来抑制锂枝晶的生长。该人工SEI膜由有机材料和无机材料复合而成，兼具无机物的强度和有机物的韧性，并且具有较高的离子电导率。通过电池测试、形貌结构表征以及光学显微镜、SEM、TEM原位观察，系统研究有机无机杂化膜对金属锂枝晶抑制作用的规律，从而对其进行不断改善，最终实现抑制锂枝晶生长，提高金属锂负极安全性能和循环性能的目标，为金属锂在下一代高能量密度电池中的应用提供理论指导和技术支持。

于高理论比容量和低工作电势，锂（Li）金属被认为是下一代高能量密度可充电电池最有希望的负极材料之一。然而锂枝晶生长和库仑效率低等问题是巨大的障碍。在这里，我们提出了一种有效的导电性多孔TiO2-C纤维布材料，该材料具有内部多孔结构作为均匀且无枝晶的Li沉积框架。由于独特的结构设计，电化学镀的Li可以被限制在纤维的孔内部以及纤维之间的空隙中，在碳酸盐电解质中经过240次循环后，平均库仑效率高达98.5％。使用LiFePO4作为正极材料的全电池在0.5 C时表现出良好的循环性能。我们希望这项工作可以为Li金属电池的Li阳极设计开辟新的机会。