NOVELTY - Polyvinyl imidazole is added to a container and spiro quaternary ammonium fluoroborate and isopropanol are added. Under inert gas atmosphere, reaction mixture is stirred, heated, precipitated using ethyl acetate, dissolved thrice in isopropyl alcohol, and dried to obtain polyethylene ionic-liquid electrolyte. Obtained polyethylene ionic-liquid electrolyte is added with solution of lithium bis(imido)trifluoromethanesulfonate and ethanol, dispersed and resultant oily liquid is washed, vacuum-dried, to obtain ionic-liquid hydrophobic polyethylene electrolyte as pale yellow solid.    USE - Preparation of ionic-liquid hydrophobic polyethylene electrolyte used for lithium-air battery (claimed).    ADVANTAGE - The method efficiently provides solid-state ionic-liquid hydrophobic polyethylene electrolyte which is not volatilized easily. The lithium-air battery using the ionic-liquid hydrophobic polyethylene electrolyte has excellent ionic conductivity and cycle characteristics.    DETAILED DESCRIPTION - 0.4-0.6 Mol 1-vinyl-3-butyl-ionic liquid is added to a container, and 50-70 ml tetrahydrofuran as solvent and 0.4-0.6 g azobisisobutyronitrile as radical initiator are added. The reaction mixture is stirred under nitrogen atmosphere, heated to 60-80 degrees C, and refluxed at constant temperature for 8-10 hours. The solvent is distilled, and dried under vacuum at 60-80 degrees C for 24-48 hours to constant weight to obtain polyvinyl imidazole as yellow solid. 0.1-0.2 Mol obtained polyvinyl imidazole is added to a container, and 0.2-0.4 mol spiro quaternary ammonium fluoroborate and 80-120 mL isopropanol are added. Under inert gas atmosphere, the reaction mixture is stirred and heated at 70-90 degrees C for 20-30 hours. The reaction mixture is precipitated using ethyl acetate, dissolved thrice in isopropyl alcohol, and dried at 70-90 degrees C for 24-36 hours under vacuum to constant weight to obtain polyethylene ionic-liquid electrolyte as yellow solid. The obtained polyethylene ionic-liquid electrolyte is added with solution of 0.5-1 mol lithium bis(imido)trifluoromethanesulfonate and 150-200 mL ethanol, dispersed for 20-30 minutes under microwave condition, and the resultant oily liquid is repeatedly washed using deionized water, and vacuum-dried, to obtain ionic-liquid hydrophobic polyethylene electrolyte as pale yellow solid.