Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications.

Li-Cheng Jheng,Hong-Yi Yeh,Chung-Yen Hsu

doi:10.3390/membranes11110901

Li-Cheng Jheng, Hong-Yi Yeh + Show 1 more

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https://doi.org/10.3390/membranes11110901

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Journal: Membranes	Publication Date: Nov 22, 2021
Citations: 9	License type: CC BY 4.0

Affiliation: National University of Kaohsiung

Abstract

Imidazoline is a five-membered heterocycle derived by the partial reduction of one double bond of the imidazole ring. This work prepared new anion exchange membranes (AEMs) based on imidazoline quaternized polystyrene copolymers bearing N-b-hydroxyethyl oleyl imidazolinium pendent groups to evaluate the application potential for anion exchange membrane fuel cells (AEMFCs). For comparison, an imidazole quaternized polystyrene copolymer was also synthesized. The polymer chemical structure was confirmed by FTIR, NMR, and TGA. In addition, the essential properties of membranes, including ion exchange capacity (IEC), water uptake, and hydroxide conductivity, were measured. The alkaline stabilities of imidazolium-based and imidazolinium-based AEMs were compared by means of the changes in the TGA thermograms, FTIR spectra, and hydroxide conductivity during the alkaline treatment in 1 M KOH at 60 °C for 144 h. The results showed that the imidazolinium-based AEMs exhibited relatively lower hydroxide conductivity (5.77 mS/cm at 70 °C) but much better alkaline stability compared with the imidazolium-based AEM. The imidazolinium-based AEM (PSVBImn-50) retained 92% of its hydroxide conductivity after the alkaline treatment. Besides, the fuel cell performance of the imidazolium-based and imidazolinium-based AEMs was examined by single-cell tests.

Highlights

Proton exchange membrane fuel cell (PEMFC) is the main type of fuel cell that can provide clean energy for many portable and transportation applications
Anion exchange membrane (AEM) is one of the main components of anion exchange membrane fuel cells (AEMFCs), which is capable of conducting anions and avoiding gas penetration from one electrode side to another side
PSVBC-30 and PSVBC-50, respectively, denote the polystyrene copolymers with the vinylbenzyl chloride (VBC) feed contents of 30 and 50 mol%, which were synthesized by thermally initiated free radical polymerization

Summary

Introduction

Proton exchange membrane fuel cell (PEMFC) is the main type of fuel cell that can provide clean energy for many portable and transportation applications. The high cost of PEMFC resulting from the use of noble metal-based catalysts still is a major obstacle for its commercialization [1,2]. Alternative to PEMFC, an anion exchange membrane fuel cell (AEMFC) having faster oxygen reduction kinetics allows platinum-free catalysts (e.g., Ag, Ni, Co, and Fe). The use of metal-based bipolar plates and lower fuel permeability are other advantages of AEMFC over PEMFC [3,4,5]. Anion exchange membrane (AEM) is one of the main components of AEMFC, which is capable of conducting anions and avoiding gas penetration from one electrode side to another side.

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