Effects of nanocon?finement on the ion conduction properties of solid state Li-based electrolytes

Abstract

Lithium-ion batteries are widely applied in many devices, ranging from mobile phones and electric vehicles to sustainable energy storage. However, they suffer from safety issues and limited energy densities. These features can be improved when the liquid electrolyte is replaced by a solid one. One of the problems that has to be overcome, is that many solid electrolytes suffer from low Li+ ionic conductivities. Nanocon?finement via melt infi?ltration is an effective and straightforward method for increasing the Li+ ionic conductivity of LiBH4, but its effect on other lithium salts has not yet been examined. In this work, the effects of nanocon?finement on the ion conduction properties of LiNH2 and LiNO3 are investigated. This is done by in?filtration in a wide range of porous metal oxide scaffolds. The resulting nanocomposites were characterized in terms of pore ?filling and infi?ltrate stability with DRIFTS, DSC and XRD, which demonstrated that the interaction of the lithium salts with the scaffold surfaces are key for successful melt infi?ltrations. These interactions are affected by the chemical nature of the scaffolds, including the presence of surface groups and acid sites, as determined with pyridine FT-IR and NH3-TPD. By tuning these interface interactions, substantial conductivity increases of more than a factor 1000 were obtained upon measuring the nanocomposite conductivities with EIS. As such, this work demonstrates that melt infi?ltration is a widely applicable and well-suited method for improving the ionic conductivity of solid electrolytes for all-solid-state battery applications.