Single-ionic conductors, which display lithium ion migration exclusively (without anion migration), have been realized as the polymeric solid electrolytes with lithium orthoaluminate repeating units carrying oligo(oxyethylene) main chain and two side chains of endomethoxy{oligo(oxyethylene)}. The ionic conductivity of the aluminate polymer complexes is about 10−6–10−7 S/cm at room temperature. Thin film lithium secondary batteries were fabricated into 5.5cm×4.5cm×0.02–0.03cm (thick) cells from lithium foil (anode), aluminate polymer complex (electrolyte) and TiS2 (cathode). These batteries show minimal decay of output voltage upon constant current discharging and their capacity of first cycle was about 146mAh/g of active cathode material. By contrast typical bi-ionic conductor of (aluminate polymer complex+5% LiClO4) hybrid system showed, on the contrary, rapid decay of output voltage, due to polarization.