Single-ionic conductors, which promote solely the lithium ion migration (without any 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 was about 10＾-6∼10＾-7S/cm at room temperature. Thin film lithium secondary batteries were fabricated into 5.5×4.5×O.02(thick) cm cells from TiS₂(cathode), aluminate polymer complex and lithium foil (anode). These batteries showed minimal decay of output voltage upon constant current discharging and their capacity of first cycle was about 147mAh/g. A typical bi-lonic conductor of (5%LiClO₄+aluminate polymer complex) hybrid system showed, on the contrary, rapid decay of output voltage due to the polarization.