2-ethylhexylamine additive boosts the transport properties of PVA-based polymer electrolyte for quasi-solid-state magnesium batteries

Abstract

Magnesium-sulfur (Mg-S) batteries offer excellent energy density, safety, and a cost-effective energy storage system. Realizing Mg-S batteries requires bypassing significant challenges like electrolyte compatibility with electrophilic sulfur and Mg metal and polysulfide shuttling. The present work probes the role of 2-ethylhexylamine (EHA) in modifying the physiochemical properties of solid polymer electrolytes (SPEs) based on polyvinyl alcohol (PVA), silicon dioxide (SiO₂), and magnesium triflate (MgTIF). The introduction of EHA increases the conductivity to approximately 10⁻⁷ S/cm at room temperature, reduces the magnesium stripping/plating overpotential, and improves the interfacial electrode/electrolyte kinetics; further, the optimum concentration (y = 3000 μl) of PVST__yEHA shows a high ionic transference number \(({t}_{{mg}^{2+}}=0.88)\) (where PVST is an abbreviation for compound composed of (PVA, SiO₂, MgTIF)), there is minimal overpotential over 100 h. Based on optimum concentration (y = 3000 μl), the Mg-S battery exhibits a high initial discharge-specific capacity in the first cycle up to 1837 mAhg⁻¹, and over six cycles, it maintained a reversible capacity of 376 mAhg⁻¹. The present article attempts to overcome some obstacles that prohibit the realization of Mg-S batteries.