Surface Modification of Lithium Battery Anodes with Multi-Functional Block Copolymers

金属锂负极因其优异的容量和最低的电化学电位而被认为是最有前途的下一代负极材料之一。然而，锂枝晶的形成和过度生长会造成一系列不良后果。它会穿透分离器，造成严重的安全隐患，并导致死锂的形成，损害库仑效率。过大的体积变化会破坏固体电解质界面层，使循环稳定性变差。这些缺点严重阻碍了金属锂电池的实际应用。提出了用多功能聚二甲基硅氧烷嵌段共聚物及其有机/无机纳米杂化材料对金属锂阳极进行表面修饰。基于PDMS的嵌段共聚物具有良好的弹性性能、优异的锂亲和性、优异的化学惰性、能够进行结构修饰和良好的溶液加工能力。它们还可以通过微相分离过程在锂金属表面形成纳米结构。改变了锂金属界面的结构和性能，抑制了锂枝晶的形成和长大，提高了固体电解质界面层的结构稳定性。该策略有效地提高了锂金属负极的电化学性能。通过这一联合项目，表面改性和器件性能研究与先进的非原位和原位散射技术(X射线和中子)相结合。建立了用多功能嵌段共聚物对金属锂阳极进行可靠的表面修饰的方法。可以很好地控制表面修饰后的锂金属负极界面的结构和性能。表面修饰金属锂负极的结构-性能关系将被揭示，其机理将被理解。该方案的实施将为金属锂电池的实际应用奠定坚实的科学基础。

Lithium metal anode is regarded as one of the most promising next generation anode materials due to its exceptional capacity and lowest electrochemical potential. Nevertheless, formation and excessive growth of lithium dendrites cause series of adverse consequences. It can penetrate the separator to cause serious safety risks and induce formation of dead lithium to harm the coulombic efficiency. Drastic volume changes tend to destroy the solid electrolyte interface layer to deteriorate cyclic stability. These drawbacks seriously hinder practical applications of the lithium metal battery. It is proposed to use multi-functional PDMS based block copolymers and their organic/inorganic nanohybrids to modify the surface of the lithium metal anodes. The PDMS based block copolymers are featured with multiple advantages such as good elastomeric property, excellent lithium affinity, outstanding chemical inertness, capable of structure modification, and good solution processing capability. They can also form nanoscale structures on the lithium metal surface via a microphase separation process. The structure and property of the lithium metal interface is modified, where the formation and growth of lithium dendrites are suppressed, and structure stability of the solid electrolyte interface layer is enhanced. With this strategy, the electrochemical performance of the lithium metal anode is effectively improved. Through this joint project, the surface modification and device performance studies are combined with advanced ex situ and in situ scattering techniques (x-ray and neutron). The methods to perform reliable surface modification of the lithium metal anodes with the multi-functional block copolymers will be established. A good control over the structure and property of the surface modified lithium metal anode interface will be achieved. The structure-performance correlation of the surface modified lithium metal anode will be unveiled, and the mechanism will be understood. The implementation of the proposal will build solid scientific ground for practical application of the lithium metal batteries.