Zhang Jiaxiang, Yang Junwen, Liu Ziyue, Zheng Bin
School of Materials Science and Engineering, Xi'an University of Science and Technology, Xi'an 710054, P. R. China.
ACS Omega. 2021 Feb 11;6(7):4995-5000. doi: 10.1021/acsomega.0c06067. eCollection 2021 Feb 23.
Lithium polysulfides (LiPSs)/sulfide are essential in secondary lithium batteries. In this work, we used density functional theory computational methods to obtain the law of constraining lithium polysulfides/sulfide by the affinitive interactions at the electronic level. The proton transfer, the orientation of polysulfides, the electron affinity, and the acid dissociation constant of small organic molecules were examined to elucidate the lithium polysulfides/sulfide binding mechanism with functional groups. The carboxyl groups exhibited a strong ability to dissolve the low-order polysulfides via proton transfer, although this type of group is highly unstable. In comparison, 1,2-diaminopropane with adjacent amino groups can strongly anchor the high-order polysulfides. The electrostatic attractions between lithium-ion and the electron-rich groups and their number and location dominated the binding energetics. Also, the entropy contribution to the binding should be considered. The information gained from these results can serve as a criterion for the selection of co-solvent for the electrolyte or postmodified functional groups for decorating the cathode in the lithium-sulfur system.
多硫化锂（LiPSs）/硫化物在二次锂电池中至关重要。在本工作中，我们使用密度泛函理论计算方法来获得在电子层面上通过亲和相互作用约束多硫化锂/硫化物的规律。研究了质子转移、多硫化物的取向、电子亲和势以及小有机分子的酸解离常数，以阐明多硫化锂/硫化物与官能团的结合机制。羧基通过质子转移表现出很强的溶解低阶多硫化物的能力，尽管这类基团非常不稳定。相比之下，具有相邻氨基的1,2 - 二氨基丙烷能够强烈锚定高阶多硫化物。锂离子与富电子基团之间的静电吸引力及其数量和位置主导了结合能。此外，还应考虑熵对结合的贡献。从这些结果中获得的信息可作为选择锂硫体系中电解质共溶剂或修饰阴极的后修饰官能团的标准。
