Beyond Li-ion electrochemical energy storage systems based on chemical transformation occupy a frontier of research and development efforts related to materials chemistry and design. Among the proposed chemistries, the combination of lithium and sulfur is recognized as one of the most promising systems with predicted values for the specific charge (1672 mAh g-1) and specific energy (2500 Wh kg-1) that are considerably higher than those of Li-ion batteries1. However, Li-S batteries are faced with a number of issues that prevent their widespread adoption. Among the most important challenges is the formation and dissolution of long chain polysulfide species in the electrolyte during cycling2. The choice of a liquid electrolyte in Li-S batteries dramatically impacts the polysulfides solubility and bulk transport processes. However, the molecular origins of the observed behavior in novel Li-S electrolytes remain poorly understood. Here, we leverage our high-throughput computational framework (MISPR; https://github.com/molmd/mispr) to build structure-property relationships of common Li-S electrolytes. The library includes 56 electrolytes spanning 16 solvent classes (e.g. ethers, sulfones, phosphates, etc.). We find a positive correlation between the binding affinity of the solvent with the salt and the polysulfide and the degree of Li&lt;font size="1"&gt;+&lt;/font&gt; ion dissociation. Ion dissociation is a critical property that impacts the ionic conductivity and thus the electrochemical performance of the battery. We elucidate the coupled motion of the electrolyte components and uncover different origins for slow dynamics depending on the solvent chemical class. In contrast to the prevailing opinion of single descriptors such as solvent dielectric constant as essential determinants of polysulfide solubility, the results of this study suggest that the observed behavior is caused by the synergistic effect of multiple factors. We expect that results from this work will help inform the development of superior Li-S electrolytes and provide novel framework for further exploration of next-generation energy storage systems.

Data-driven investigation of solvents for lithium-sulfur battery liquid electrolytes

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.