Lithium Polysulfide Adsorption to UiO-66 Missing Linker Defect Sites for Applications in Li-S Batteries: A Density Functional Theory Study

• Main Author: Jarrin, Roberto Andres
• Other Authors: Bukowski, Brandon, Clancy, Paulette
• Format: Thesis
• Language: English
• Published: Johns Hopkins University 2023
• Subjects: DFT; Batteries; Computational; Orca
• Online Access: http://jhir.library.jhu.edu/handle/1774.2/68592

Lithium sulfur (Li-S) batteries are a promising alternative to Li-ion batteries due to their higher theoretical specific capacity and energy density. However, several problems have proven difficult to overcome, including the polysulfide shuttle effect. The diffusion of liquid polysulfide intermediates into the electrolyte causes a loss of active material that leads to decreased capacity and poor cycling stability. Many materials have therefore been the subject of study for anchoring diffusing lithium polysulfides. The metal organic framework UiO-66 has emerged as one such promising material due to its porosity and high surface area. Using the ORCA program, we perform computational experiments to model the molecular interactions between lithium polysulfides and UiO-66. The purpose of this work is to explore how lithium polysulfides adsorb to open sites caused by missing linker defects as well as sites functionalized with alkali metals. Our results demonstrate that lithium polysulfides adsorb favorably to UiO-66 prominently through Li-O electrostatic interactions and hydrogen shifts. In addition, node functionalization with alkali metals improves lithium polysulfide adsorption by facilitating charge transfer. We did not find significant differences in lithium polysulfide adsorption favorability between alkali metals. Our findings support the capacity of functionalized UiO-66 to inhibit the shuttle effect and improve Li S battery performance.