Abstract Nanoscopic confinement of a cation coordinated polymer in the channels of organo-modified montmorillonite clay results in substantial improvement in conductivity, cation transport and stability properties required for energy storage/conversion devices. X-ray diffraction analysis confirms composite formation as evidenced by: (i) intercalation of PEO 8–LiClO 4 into the clay channels for clay loading ≥7.5 wt.% and (ii) partial intercalation/exfoliation for a lower clay loading (≤5 wt.%). Transmission electron microscopy analysis corroborates these findings as indicated by an enhancement in clay gallery width from 6 to 9 Å for 20 wt.% clay providing evidence for intercalation at higher clay loadings. Energy dispersive X-ray dot-mapping images confirm the homogeneous distribution of clay in nanocomposites. Thermal analysis indicates a strong dependence of thermodynamic parameters, e.g., glass transition ( T g), crystalline melting ( T m), melting enthalpy, glass transition width (Δ T g), and thermal relaxation strength (Δ C p), on clay concentration. These observations agree well with changes in electrical properties on nanocomposite formation. Substantial enhancement in ambient conductivity (∼208 times) occurs in a nanocomposite film (2 wt.% clay) relative to a clay-free film. The temperature dependence of conductivity obeys Arrhenius behaviour below T m and the VTF (Vogel–Tamman–Fulcher) relationship above T m. The ionic transport number (∼99.9%) confirms ionic charge transport with a cation contribution ( t L i + ) ∼ 0.5 for 2 wt.% clay. It represents an increase by ∼65% in comparison with PEO 8–LiClO 4. Improvement in voltage and thermal stability is also observed with the nanocomposites.