Mechanically Stable Thinned Membrane for a High-Performance Polymer Electrolyte Membrane Fuel Cell via a Plasma-Etching and Annealing Process

Abstract

A thin electrolyte membrane is highly demanded for achieving high-performance polymer electrolyte membrane fuel cells (PEMFCs) by taking advantage of the reduced ohmic resistance-driven enhanced proton- and water-transport property during the PEMFC operation. However, the thin membrane inherently suffers from poor mechanical properties. In this study, we propose a simple methodological approach that combines the plasma etching and thermal annealing process to construct mechanically stable thinned membrane using commercially available Nafion membranes. The morphological, mechanical, and chemical properties of the modified Nafion membranes were characterized through diverse measurements including field-emission scanning electron microscopy, atomic force microscopy, stress–strain behavior test, and Fourier transform infrared spectrometry. We observed that the plasma etching process effectively reduced the membrane thickness; however, it induced spike-like structures with hundreds of nanometers in size on the membrane surface, which can cause stress-concentration-induced mechanical degradation of the membrane. By adopting a consecutive thermal annealing process, the roughened surface was flattened and mechanical properties including tensile strength and elongation to break were successfully recovered while maintaining the chemical composition of the Nafion. Interestingly, the modified 15 μm-thick Nafion membrane with the plasma etching and thermal process showed a much enhanced maximum power density of 22.5 and 13.6% under the low and high humidity condition of RH 45% @89.5 °C and RH 92% @70 °C, respectively, compared to that of a pristine 25 μm-thick Nafion membrane.

Study on the Effect of Water Flux in Osmotic Microbial Fuel Cells on Membrane Water Content and Resistance

“…The first form especially occurs when there are large osmotic pressure differences because of the difference in density adjacent to the membrane (see Equation ( 6)) [20]. In the context of OsMFCs, the delivery of water bound to protons is called electro-osmosis [21], which occurs when the protons are going through the membrane [22].…”

Pore-Scale Modeling of Mass Transport in Partially Saturated Cathode Gas Diffusion Layers of Proton Exchange Membrane Fuel Cell

“…In the transformation of the global energy structure to clean, low carbon, and environmentally friendly, the zero-emission, nonpolluting, high-power, long-range proton exchange membrane fuel cell (PEMFC) has received extra attention of many companies and countries. PEMFCs are even considered the ultimate solution for transportation and distributed power plants. , PEMFCs convert chemical energy directly into electrical energy by means of the electrochemical reaction between hydrogen and oxygen. The main factor limiting the efficiency of a PEMFC is the difficulty of maintaining the water balance and thermal equilibrium. , In general, too little liquid water cannot keep the proton exchange membrane in good wetting conditions and thus increases the mass transfer resistance.…”

“…PEMFCs are even considered the ultimate solution for transportation and distributed power plants. 1,2 PEMFCs convert chemical energy directly into electrical energy by means of the electrochemical reaction between hydrogen and oxygen. The main factor limiting the efficiency of a PEMFC is the difficulty of maintaining the water balance and thermal equilibrium.…”

Investigation on the Microscopic/Macroscopic Mechanical Properties of a Thermally Annealed Nafion® Membrane

“…However, suitable loadings of the additives and elaborate fabrication processes are required to avoid reduced proton conductivity and membrane cracking due to significant phase separation. As one of the methods for modifying mechanical properties without incorporating additional materials, thermal treatment of the pristine membrane is the most widely used process [25][26][27][28][29]. Until now, most studies have focused on investigating the bulk mechanical properties, such as tensile strength, Young's modulus, and elongation to break.…”