Park, C.; Kanduc, M.; Headen, T.F.; Youngs, T.G.A.; Dzubiella, J.; Risse, S.: Toward unveiling structure and property relationships from ionic ordering in Li/S battery electrolytes: Neutron total scattering and molecular dynamics simulations. Energy Storage Materials 52 (2022), p. 85-93
10.1016/j.ensm.2022.07.008
Open Access Version
Abstract:
With their high energy density and environmental friendliness, lithium/sulfur (Li/S) batteries represent a promising candidate for the post-lithium-ion era. However, complex degradation mechanisms and a lack of microscopic insight into the molecular structure of the polysulfide (PS) and ether-based electrolyte materials have hindered the broad commercialization of this energy storage system so far. Here, neutron scattering experiments combined with electronic-continuum corrected molecular dynamics simulations of typical ether-based electrolytes for lithium/sulfur batteries were used to elucidate the complex electrolyte and PS structure. We find that a delicate balance between ion-ion and ion-solvent interactions steers the ordering and undesired clustering of Li^+ and PS ions at moderate concentrations (> 1 M). In particular, ‘solvent-separated’ Li^+ ions and PS/anions induce a cation and anion short-ranged alternating structure. At these moderate concentrations, we show the onset of the decoupling of diffusion processes of Li^+ ions into caged and jump diffusions within the 3D TFSI^- networks. Our study and the presented combination of methods are extendable to other electrolytes and compositions and provide a significant step forward in the modeling and understanding of next-generation battery materials.