The interaction behavior of polymer electrolytes composed of poly(vinyl pyrrolidone) and lithium perchlorate (LiClO4)

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 comparted 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 LiClO4 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.