Rational Design of Barrier Films to Enable Rechargeable Mg-S Batteries

镁硫(镁S)充电电池是一种潜在的低成本和高能量密度的解决方案，用于电动交通。这项技术的一个技术障碍是，到目前为止，与硫磺阴极一起使用时，可充电镁金属电池的电解液要求限制了循环寿命。在这个项目中，PI将进行用于电解液-阴极界面的紫外光固化聚合物阻挡膜的基础研究，以实现电池的容量保持。功能性聚合物薄膜将防止某些活性物种的交叉，从而减轻有害反应，并保持电池的阳极、电解液和阴极的化学完整性。这项工作产生的基本科学知识可以使新材料在其他应用中取得进展，在这些应用中，性能特性受到离子传输和离子排斥的影响。此外，化学科学和工程学下一代研究人员的数量、多样性和培训将通过进一步开发高中推广单元以及扩大妇女和代表不足的少数族裔本科生和研究生对研究的参与而得到加强。该项目解决了镁-S电池发展中的两个基本限制：通过与电解液物种的反应分解活性正极材料和通过正极中间体钝化负极。这两个问题都可以通过防止不受欢迎的物质在电解液-阴极界面上的传输来缓解。使镁-S电池循环的聚合物阻挡膜的结构-性能关系将被问及。在该项目的第一个主题中，将通过将高度可分解的镁滴定离子单体与各种化学和长度不同的双官能低聚单体进行交联来创建自支撑薄膜。非原位研究将评估薄膜在传导镁离子和排除阴离子多硫化物和/或亲核络合物方面的效果。空间排斥、介电排斥和静电排斥的机理将独立探讨。在第二个主题中，可紫外光固化的阻隔膜将被直接涂覆在硫磺阴极片上。研究了膜的厚度、一致性和化学成分对全电池镁S电池性能的影响。电池的性能将与薄膜的基本特性联系在一起。

Magnesium-sulfur (Mg-S) rechargeable batteries are a potentially cost-effective and high energy density solution for use in electric transportation. One technical barrier to this technology is that the electrolyte requirements for rechargeable Mg metal batteries have thus far limited cycle life when used with sulfur cathodes. In this project, the PI will conduct fundamental research on UV light-curable polymeric barrier films for the electrolyte-cathode interface to enable capacity retention of the battery. The functional polymeric films will prevent cross-over of certain reactive species, thus mitigating deleterious reactions and maintaining chemical integrity of the anode, electrolyte, and cathode of the battery. The fundamental scientific knowledge generated by this work could enable advances in new materials for other applications where performance characteristics are influenced by ion transport and ion rejection. Additionally, the number, diversity, and training of the next generation of researchers in the chemical sciences and engineering will be enhanced by the further development of an outreach module for high schools and by the broadening participation of women and underrepresented minority undergraduate and graduate students in research. This project addresses two fundamental limitations in Mg-S battery development: breakdown of active cathode material by reaction with electrolyte species and passivation of the anode by cathode intermediates. Both issues may be mitigated by preventing the transport of undesirable species across the electrolyte-cathode interface. Structure-property relationships of polymeric barrier films to enable Mg-S battery cycling will be interrogated. In the first theme of the project, self-supporting films will be created by crosslinking of a highly dissociable magnesium-titrated ionic monomer with a variety of difunctional oligomeric monomers of varying chemistry and length. Ex-situ studies will evaluate the efficacy of the films in conducting magnesium cations and excluding anionic polysulfides and/or nucleophilic complexes. The mechanisms of steric, dielectric, and electrostatic exclusion will be independently probed. In the second theme, the UV-curable barrier films will be blade coated directly onto sulfur cathode sheets. Effects of thickness, conformity, and chemistry of the films on full cell Mg-S battery performance will be investigated. The performance of the cells will be linked with the fundamental characteristics of the films.