Pore-Filled Anion-Exchange Membranes with Double Cross-Linking Structure for Fuel Cells and Redox Flow Batteries

Moon-Sung Kang,Do-Hyeong Kim

doi:10.3390/en13184761

Abstract

In this work, high-performance pore-filled anion-exchange membranes (PFAEMs) with double cross-linking structures have been successfully developed for application to promising electrochemical energy conversion systems, such as alkaline direct liquid fuel cells (ADLFCs) and vanadium redox flow batteries (VRFBs). Specifically, two kinds of porous polytetrafluoroethylene (PTFE) substrates, with different hydrophilicities, were utilized for the membrane fabrication. The PTFE-based PFAEMs revealed, both excellent electrochemical characteristics, and chemical stability in harsh environments. It was proven that the use of a hydrophilic porous substrate is more desirable for the efficient power generation of ADLFCs, mainly owing to the facilitated transport of hydroxyl ions through the membrane, showing an excellent maximum power density of around 400 mW cm−2 at 60 °C. In the case of VRFB, however, the battery cell employing the hydrophobic PTFE-based PFAEM exhibited the highest energy efficiency (87%, cf. AMX = 82%) among the tested membranes, because the crossover rate of vanadium redox species through the membrane most significantly affects the VRFB efficiency. The results imply that the properties of a porous substrate for preparing the membranes should match the operating environment, for successful applications to electrochemical energy conversion processes.

Highlights

Ion-exchange membranes (IEMs), which can selectively transport counter ions having the opposite charge to the fixed charge groups, and connected to the membrane matrix by means of the Donnan exclusion, have been widely utilized in many desalination processes such as electrodialysis (ED) [1,2,3], diffusion dialysis (DD) [4,5], membrane capacitive deionization (MCDI) [6,7,8], etc
IEMs have been successfully applied in several electrochemical energy production and storage systems, including fuel cells (FCs) [9,10,11,12,13], reverse electrodialysis (RED) [14,15], redox flow batteries (RFBs) [16,17,18,19]
In the spectra of both the base membrane (PS + Poly(DMAEMA-DVB)) and pore-filled anion-exchange membranes (PFAEMs) (PS + Poly (DMAEMA-DVB-Xylylene dichloride (XDC))), the absorption bands at 1726 cm−1 and 1456 cm−1, which are assigned to the stretch vibration of carbonyl group (C=O), and the C=C in plane stretch vibration of the benzene ring, respectively, indicating the successful in situ synthesis of poly(DMAMEA-DVB) inside the pores of the PTFE substrate [42]

Summary

Introduction

Ion-exchange membranes (IEMs), which can selectively transport counter ions having the opposite charge to the fixed charge groups, and connected to the membrane matrix by means of the Donnan exclusion, have been widely utilized in many desalination processes such as electrodialysis (ED) [1,2,3], diffusion dialysis (DD) [4,5], membrane capacitive deionization (MCDI) [6,7,8], etc. IEMs have been successfully applied in several electrochemical energy production and storage systems, including fuel cells (FCs) [9,10,11,12,13], reverse electrodialysis (RED) [14,15], redox flow batteries (RFBs) [16,17,18,19]. Proton-exchange membranes (PEMs), such as Nafion, have been widely utilized in energy conversion processes, owing to their excellent proton conductivity and chemical stability [20].

Methods

Results

Conclusion