Modulation of ion transference number by dynamic hydrogen bond network

Ionic liquids (IL) are important materials with potential to be used in various technologies because of their non-toxicity, non-flammability, and high ionic conductivity. Although high conductivity in ionic liquids can be achieved, their relatively low transference number remains a problem. Ionic materials with high transference number are required to design high power batteries. In the present talk, we demonstrate that addition of small nanoparticles capable of formation of hydrogen bonds can reduce electrostatic interaction between ions in IL which improves ion dissociation. Furthermore, with increase in concentration of nanoparticle a clear evidence of network formation has been obtained from rheology. By studying various aspects of diffusion, conductivity, and dynamics in the network at ambient and elevated pressure, we found that formation of the network promotes decoupling between ion conductivity and structural relaxation and controls ion diffusion trough hydrogen bond network. Our studies provide fundamental insights into decoupling phenomena which is a major mechanism of conductivity in solid ion conductors. Furthermore, introduction of additional interaction into IL seems to be a promising direction to control diffusion of the ions.