Study on the interaction between lithium ion and polar group in GPE based on the crosslinked polymer of P(MMA-MAh)-PEG1500 with FTIR

The crosslinked polymer of P (MMA-MAh)-PEG1500 was synthesized by reacting polyethylene glycol (PEG1500) with the copolymer of poly (methyl metacrylate-maleic anhydride) (P (MMA-MAh)) and endcapping the residual carboxylic acid with methanol. The properties of gel polymer electrolyte (GPE), consisted of P (MMA-MAh)-PEG1500 used as polymer matrix, propylene carbonate (PC) as a plasticizer and LiClO₄ as lithium ion producer, was undoubtedly depended on the micro interaction existed in the components. Characterization of interaction of the polar group (C=O and C-O-C) in PC or crosslinked polymer with Li⁺ has been thoroughly examined using FTIR. The quantitative analysis of FTIR showed that the absorptivity coefficient (a) of PC/LiClO4 and polymer/LiClO4 was 0.113 and 0.267, respectively, which meant that the Li⁺ bonded polar group of C=O and C-O-C was more sensitive than free C=O and C-O-C in FTIR spectra. The limit value of bonded C=O and C-O-C equivalent fraction of PC/LiClO₄ and polymer/LiClO₄ was 94% and 45%, respectively, which implied that the interaction within the components was reversible and the intensity of interaction was ordered as PC/LiClO₄ and polymer/LiClO₄.