Alkaline Iodide-Based Deep Eutectic Solvents for Electrochemical Applications

Abstract

Deep eutectic solvents (DES) composed of lithium, sodium, or potassium iodide salts in suitable combination with ethylene glycol (EG), glycerol (Gly), or polyethylene glycol (PEG) have been developed. All prepared DES were characterized by thermal analysis (DSC and TGA) and its complex conductivity (σ*) and impedance (Z*) frequency were evaluated through dielectric relaxation spectroscopy (DRS). Two- and three-electrode electrochemical studies of all DES have been performed. All DES avoid crystallization, exhibiting conductivity values in a range from 10–4 to 10–2 S cm–1 at room temperature and electrochemical windows higher than 1 V (on the order of 3–4 V), fulfilling the usual suitability criteria for utilization in electrochromic devices (ECD). The most promissory DES as electrolytes were tested for ECD. Being suitable candidates for further application in batteries.