Designing of a Urea-Containing Polymer Gel Electrolyte Based on the Concept of Activation of the Interaction between the Carrier Ion and Polymer

• Published in: The journal of physical chemistry. B Vol. 107; no. 34; pp. 8805 - 8811
• Main Authors: Saito, Yuria, Kataoka, Hiroshi, Murata, Shuuhei, Uetani, Yoshihiro, Kii, Keisuke, Minamizaki, Yoshihiro
• Format: Journal Article
• Language: English
• Published: American Chemical Society 28.08.2003
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp034790l

The development of new materials for energy conversion systems is a pressing need for dealing with the energy problem and environmental preservation of the earth. On the basis of these demands, a new type of polymer gel electrolyte for lithium secondary batteries was prepared in this research using the concept of restricting the anion mobility with the chemical interactive effect of a specific site of the polymer in the gel. The polymer having the urea group CBMEU was designed to use the electron donating and withdrawing effect of the urea group for attracting the cation and anion, respectively, for the demands of promoting the dissociation of the salt and reducing the anion mobility. To quantitatively confirm the interactive effect of the polymer site, a theoretical model was set up based on the observed dynamic values to estimate the dissociation degree of the salt and interactive force. Application of the model to the new polymer gel electrolyte (CBMEU gel) and the PEO-type gel for comparison showed that, during the progress of gelation, the interactive effect of the polymer on the ionic species promoted the dissociation of the salt and reduced the ionic mobility. The absolute value of the interactive force of the cation, γ cation, was greater than that of the anion, γ anion, for both gels. The ratio, γ cation/γ anion, of the PEO-type gel was three times larger than that of the new polymer gel electrolyte. This is attributed to the anion-attracting effect of the urea group of the CBMEU gel in contrast to only the cation-attracting behavior of the ether oxygen of the PEO-type gel. From this investigation, we proposed an idea to design the polymer gel electrolyte which provides a high dissociation degree and cation transport number based on the investigation of the dynamic properties.