Systems of linear poly(ethylenimine) (LPEI) complexed with lithium triflate (LiTf), lithium hexafluoroantimonate (LiSbF6), and tetrabutylammonium hexafluoroantimonate (TbaSbF(6)) were studied via FT-IR spectroscopy to determine the changes in ion-polymer and ion-ion interactions that the complexes undergo with changes in salt concentration and temperature. General trends toward loss of order in both the LPEI:LiTf and LPEI:LiSbF6 systems were noted with increasing temperature as well as increasing salt concentration, leading to the conclusion that an interaction between the polymer and the lithium cation drives the disordering of the two systems. Speciation of the triflate anion was found to be dependent on salt concentration but independent of temperature. In the hexafluoroantimonate systems, the spectral shift of the anion is due to interaction with the polymer rather than interaction with the lithium cation.