Theory-Enabled High-Throughput Screening of Ion Dissociation Explains Conductivity Enhancements in Diluted Ionic Liquid Mixtures

The growing demand for room-temperature ionic liquids (RTILs) for energy applications necessitates the development of an efficient screening platform. In this study, we have successfully developed a fully automated high-throughput RTIL screening platform specifically designed for assessing ionic conductivity. By utilizing the 96-wells of a microtiter plate as individual electrolysis cells, we measured ionic conductivity of 22 different RTILs, encompassing various combinations of cations and anions, and benchmarked the values with existing literature. We also employed the screening platform to investigate the conductivities of RTIL mixtures with a non-aqueous solvent, ethylene glycol (EG). Our results reveal specific combinations of RTILs with EG that result in approximately 200% enhancement in the conductivity values as compared to the pure RTILs. To understand the underlying mechanisms responsible for this enhancement, we developed a theoretical framework that considers factors such as degree of dissociation, viscous forces, and molal volume of the RTIL-EG mixtures. The optimized electrolyte mixture was then employed in the migration-assisted moisture gradient (MAMG) CO2 capture process to study the effects of improved ionic conductivity on the energy efficiency of the process. Notably, the enhanced conductivity of the RTIL-EG mixture led to nearly 50% reduction in energy consumption for capturing CO2. These outcomes highlight the effectiveness of our strategy in screening RTILs and improving existing processes. Moreover, our fully automated high-throughput setup, combined with the developed theoretical framework, provides a comprehensive platform for screening and studying RTIL mixtures with different solvents, enabling their application in various fields.