Polyethylene oxide and ionic liquid-based solid polymer electrolyte for rechargeable magnesium batteries

Solid polymer electrolytes (SPEs) based on polyethylene oxide (PEO) complexed with magnesium triflate Mg(Tf)(2) or Mg(CF3SO3)(2)) and incorporating the ionic liquid (IL) (1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI)) were prepared by solution cast technique. The electrolyte was optimized and characterized using electrical conductivity, cationic transport number measurements, and cyclic voltammetry. The highest conductivity of the PEO/Mg(Tf)(2), 15:1 (molar ratio), electrolyte at room temperature was 1.19 x 10(-4) S cm(-1) and this was increased to 3.66 x 10(-4) S cm(-1) with the addition of 10 wt.% ionic liquid. A significant increase in the Mg2+ ion transport number was observed with increasing content of the ionic liquid in the PEO-Mg(Tf)(2) electrolyte. The maximum Mg2+ ion transport number obtained was 0.40 at the optimized electrolyte composition. A battery of the configuration Mg/ and [(PEO)(15):Mg(Tf)(2)+10%IL]/TiO2-C was assembled and characterized. Preliminary studies showed that the discharge capacity of the battery was 45 mA h g(-1).