Chloroaluminate Gel Electrolytes Prepared with Copolymers Based on Imidazolium Ionic Liquids and Deep Eutectic Solvent AlCl3:Urea.

Jesús L Pablos,Teresa Corrales,Pilar Tiemblo,Gary Ellis

doi:10.3390/polym13071050

Jesús L Pablos, Teresa Corrales + Show 2 more

Open Access

https://doi.org/10.3390/polym13071050

Copy DOI

Journal: Polymers	Publication Date: Mar 27, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Instituto de Ciencia y Tecnología de Polímeros

Abstract

Polymer gel electrolytes (PGEs) have been prepared with copolymers based on imidazolium ionic liquids and the deep eutectic mixture of AlCl3:urea (uralumina) as liquid electrolyte. The copolymers were synthesized by photopolymerization of vinylpirrolidone or methylmethacrylate with imidazolium bis (trifluoromethane sulfonyl) imide (TFSI) ionic liquid monomer and mixed in an increasing range of wt.% with uralumina. The rheology and electrochemical activity of PGEs were highly dependent on the molar ratio of charged groups and copolymer content. Structure of the PGEs was studied by FTIR and Raman spectroscopy and a correlation between interactions polymer/uralumina and changes in speciation of uralumina was established. Despite the low molecular weight of the copolymers, the resulting polymer electrolytes develop elastomeric character associated with the binding ionic species. Although there is room to improve the electrochemical activity, in this study these new gels provide sufficient electroactivity to make them feasible alternatives as electrolytes in secondary aluminum batteries.

Highlights

In recent years, the development of aluminum-based batteries is considered of great interest as a potential alternative to the well-established lithium ion battery [1]
Copolymers based on vinylpirrolidone or methylmethacrylate and imidazolium bis imide (TFSI) ionic liquid have been synthesized and mixed with U150 to obtain polymer gel electrolytes
Because of the limited ability of the deep eutectic solvent (DES) to dissolve polymers, together with thermal stability of U150, copolymers were designed with a glass transition temperature of around 70 ◦C, P(VP70-co-IMMA30), P(MMA80-coIMMA20), and P(MMA69-co-IMMA31)

Summary

Introduction

The development of aluminum-based batteries is considered of great interest as a potential alternative to the well-established lithium ion battery [1]. In the literature dedicated to aluminum secondary batteries, only a few studies have report the use of polymers to prepare solid electrolytes instead of liquid ones These include the in-situ polymerization of acrylamide in a deep eutectic solvent (DES) [4], and more recently, the dissolution of a commercial polymer (PEO) in uralumina U150 (AlCl3:Urea 1.5:1 in molar ratio), which is dimensionally stable as result of the strong interactions between the polymer and the DES [5]. The study of solubility in U150 of commercial polymers of varied chemical structure and physicochemical characteristics indicates that polymers have a liquid state at the mixing temperature and the presence of oxygen groups in the polymer chain in common Both these conditions are necessary but not sufficient, since PVP and PMMA contain interacting chemical groups that could allow the control of the crosslinking points in copolymers with DES, but are insoluble in U150, and do not swell either [14]. The structure and properties of the polyelectrolytes have been studied to determine the interactions of polymers and chloroaluminates, which contribute to balance the rheology and electrochemistry in these gel electrolytes

Materials

Preparation Procedure

Structure of the PGEs by FTIR and Raman Spectroscopy

Conclusions