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

Abstract

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.

Multi-scale structural description of siloxane–PPO hybrid ionic conductors doped by sodium salts

“…This complexation can be explained by the strong Lewis base character of both anions and strong Lewis acid character of the NH group. Our experimental results give direct evidence of the predictive ab initio calculations reported by Saito et al 26 for the complexation of PF 6 2 anions on polymeric gel containing urea groups and suggest that such complexation may be universal behavior for strong Lewis base anions. Furthermore, the interaction of ClO 4 2 ions with Na + can be discarded from the 1).…”

“…Thus the conjunction of local order techniques (NMR, XANES, Raman…) such as done in this paper is a unique way to obtain insight into the structures of PPO based materials. As the strength of interactions between anions and the cylinder-like polymeric chains is lower than that between anions and NH of urea groups, 26 and, as the proportion of anion interactions with the PPO chains increases as the doping level tends to [U]/[Na] = 1, a macroscopic increase of the anionic mobility is expected. On the other hand, the sodium mobility should strongly decrease with the increase of extension of the TG a T polyether conformation along the chains.…”

“…In fact, urea binds to alkali metals because of its resonant structure, 25 while the acidic character of the N-H bonds helps ionic dissociation and creates interactions with the anions as stated from a recent ab initio calculation. 26 In summary, cations could be equally solvated by PPO or carbonyl groups, as anions interact slightly with PPO while they could be attracted by the NH of the urea group, restraining their mobility. 19,27 Therefore, this paper presents and compares the behavior of two sodium salts, NaBF 4 and NaClO 4 , dissolved in a siloxane-PPO class {II} hybrid by a multi-spectroscopic approach.…”

Existing Condition and Migration Property of Ions in Lithium Electrolytes with Ionic Liquid Solvent

“…12,13 In this approach, a constant electric field is applied to detect the ions of the probed nucleus selectively. Different from the conventional electrolytes with the neutral solvent, it is principally hard to measure the lithium ion mobility in the ionic liquid solvent using this technique because not only the target lithium ions but also the solvent ions drift in response to the applied electric field.…”

Star-shaped oligo(ethylene glycol) ethers (OEGE) as a new type of plasticizer for polymer gel electrolytes

“…Polar polymer matrices and plasticizers are used to achieve high contents of free ions for high ionic conductivities. In the literature, there are described several polymers which are suitable as matrix materials, such as poly(vinylidene fluoride) [1], poly(acrylonitrile) [2], poly(methylmethacrylate) [3], poly(vinyl chloride) [4], poly(ethylene oxide) [5], polyurethane [6] and an urea group containing polymer [7]. In the last time, the development of diverse polar copolymer matrices has been intensified [8 -11].…”