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 (SiO 2 ), 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_ y EHA shows a high ionic transference number $$({t}_{{mg}^{2+}}=0.88)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>t</mml:mi> <mml:msup> <mml:mrow> <mml:mi>mg</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.88</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> (where PVST is an abbreviation for compound composed of (PVA, SiO 2 , 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.