Ethylene carbonate plasticized polymer electrolyte for chloride ion batteries with enhanced reversible capacity

Chloride ion batteries (CIB) are attracting more and more attention in recent years because of abundant chloride sources, high energy density, and high safety. The electrode dissolution into the liquid electrolyte remains a great challenge in CIBs. Exploring solid polymer electrolyte provides a feasible solution to address this issue. Herein, a novel gel polymer electrolyte composed of poly(ethylene oxide) (PEO) as a host polymer, tributylmethylammonium chloride (TBMACl) as a salt, and ethylene carbonate (EC) as a plasticizer was prepared by a solution casing method. The addition of plasticizer can not only decrease the PEO crystallinity but also increase salt dissociation. As a result, the ionic conductivity of the plasticized PEO-TBMACl-EC polymer electrolyte reached 5.27 × 10⁻⁵ S cm⁻¹ at room temperature, which is much higher than 3.45 × 10⁻⁷ S cm⁻¹ of the unplasticized PEO-TBMACl polymer electrolyte. When assembled into CIBs with the FeOCl/Li electrode couple, higher reversible capacities were achieved with the plasticized PEO-TBMACl-EC polymer electrolyte compared to unplasticized PEO-TBMACl polymer electrolyte.