Supervisor: Yevheniia Lobko, Ph.D.
Such alternative and eco-friendly energy sources as the anion exchange membrane (AEM) fuel cells and water electrolyzers are very perspective, and comparably cheap. However, the weak point in this technology is a membrane.
The aim of this work is to overcome one of the key limitations of anion exchange membrane, namely water management combined with the improved mechanical and electrochemical performance. The new advanced polymer membranes (stable over a wide temperature range) will be elaborated by the polymer chemical modification and by poly(ionic liquid) incorporation and immobilization inside the polymer matrix. The membrane properties will be evaluated in terms of ion conductivity, mechanical stability and transport properties. The influence of the following factors, i.e. the ionic liquid structure (cation and anion), the mode and conditions of membrane preparation, will be taken into account. Surface-sensitive techniques, specifically scanning electron microscopy (SEM) and atomic force microscopy (AFM), will be utilized to perform a surface morphology analysis of the membranes. This analysis aims to investigate the influence of the surface roughness, homogeneity, and distribution of the polymer heterogeneous blocks or/and ionic liquids on the mechanical and transport properties of the membranes. The X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and Raman spectroscopy will be performed to study the surface chemistry and reactions of the AEMs due to provide insights into the chemical and electrochemical behavior of the membrane under operating conditions. Moreover, in-operando XPS in water electrolyzer mode will be used for the investigation of the hydroxide anions’ diffusion in the thin layer of the catalysts, as well as through the membrane. Electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) can be used to study the membrane's ion conductivity, charge transfer resistance, hydrogen and oxygen cross-overs, and durability in-situ.
By combining these surface studies with bulk membrane characterization techniques (such as thermally gravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical testing, etc.), it is possible to gain a comprehensive understanding of the AEM's properties and behavior, which can aid in the development of more efficient and durable AEM-based electrochemical systems. Particular attention will be paid on the preparation of membrane electrode assembly using ultrasonic spray-coating and Meyer rod techniques. The overall cyclic performance of the elaborated electrochemical system will be examined in electrolyzer and fuel cell modes.
The main goal of the work is the establishment of the relationship between the structure, morphology, activity, and durability of the AEM membranes in operando in both fuel cells and electrolyzer.
