The interaction behavior of polymer electrolytes composed of poly(vinyl pyrrolidone) (PVP) and lithium perchlorate (LiClO4) has been investigated in detail by solid-state NMR and FTIR spectroscopies. It is found that the N-atom of the PVP polymer is able to donate its lone pair electrons toward the C=O group, which results in a higher basicity of the C=O group. The complex bond of Li+... C=O is compared into two types: the tight primary complex bond of Li+ C=O; and the secondary complex where Li+ loosely complexed with several C=O groups simultaneously. The secondary complex is dominant when the [Li:O] ratio is greater than 0.281. The ClO4- anion is free in the diluted PVP/LiClO4 electrolyte. When the LiCl4 concentration is increased, the ClO4- anion will interact with both N quasi-cation and/or Li+ cation. Solvated Li+ and "free" ClO4- ions are more favorable in diluted electrolyte; whereas neutral solvation-shared ion pair formation increases the incremental addition the LiClO4.