Locally concentrated electrolytes for aluminum-sulfur metal batteries: a molecular dynamics study

Aluminum–sulfur (Alsingle bondS) batteries are a promising alternative to conventional lithium-ion systems due to the greater abundance, safety, and sustainability of aluminum. However, the development of compatible electrolytes remains a critical issue. In this work, we present a molecular dynamics study of two classes of acidic electrolytes based on AlCl3 diluted with different concentrations of 1,2-difluorobenzene (dFBn): the first contains an ionic liquid (EMIM); the second is based on a deep eutectic solvent with urea. The results show that the EMIM-based electrolyte maintains a homogeneous structure, with weak interactions between neutral and charged species and high ionic mobility while the urea-based electrolyte exhibits pronounced nanoscale segregation, with the formation of distinct domains and strong association between urea and [AlCl₂]+ ions, leading to reduced mobility.