Tuning the Formation and Structure of the Silicon Electrode/Ionic Liquid Electrolyte Interphase in Superconcentrated Ionic Liquids.

The latest advances in the stabilization of Li/Na metal battery and Li-ion battery cycling have highlighted the importance of electrode/electrolyte interface [solid electrolyte interphase (SEI)] and its direct link to cycling behavior. To understand the structure and properties of the SEI, we used combined experimental and computational studies to unveil how the ionic liquid (IL) cation nature and salt concentration impact the silicon/IL electrolyte interfacial structure and the formed SEI. The nature of the IL cation is found to be important to control the electrolyte reductive decomposition that influences the SEI composition and properties and the reversibility of the Li-Si alloying process.

Molecular dynamics simulations of pyrrolidinium and imidazolium ionic liquids at graphene interfaces.

Understanding the electrode-electrolyte interface is essential in the battery research as the ion transport and ion structures at the interface most likely affect the performance of a battery. Here we investigate interfacial structures of three ionic liquids: 1-ethyl-3-methylimidazolium dicyanamide ([Cmim][dca]), 1-butyl-3-methylimidazolium dicyanamide ([Cmim][dca]) and N-butyl-N-methylpyrrolidinium dicyanamide ([Cmyr][dca]) at a charged and uncharged graphene interface using molecular dynamics simulations. We find that these ionic liquids (ILs) behave differently both in the bulk phase and near a graphene interface and we find that this difference is apparent in all types of analyses performed here.

A comparative AFM study of the interfacial nanostructure in imidazolium or pyrrolidinium ionic liquid electrolytes for zinc electrochemical systems.

The electrochemical systems containing zinc dicyanamide salt (Zn(dca)) in both 1-ethyl-3-methylimidazolium dicyanamide ([Cmim][dca]) and N-butyl-N-methylpyrrolidinium dicyanamide ([Cmpyr][dca]) ionic liquids (ILs) have been studied by atomic force microscopy (AFM) on a highly oriented pyrolytic graphite (HOPG) surface under different conditions and applied potentials. The results reveal the following: (1) interfacial layers exist in both ILs, even after the addition of 3 wt% water and 9 mol% Zn(dca) salt. (2) The number of layers is different for the different ILs, with the [Cmim][dca]-based samples exhibiting a much more limited interfacial structure compared to the [Cmpyr][dca] at almost all of the tested conditions.