Advanced composite electrolyte membranes for energy conversion and green-H2 production

A. Bose
University of Houston,
United States

Keywords: fuel cell, water electrolysis, proton exchange membrane, electrolyte membrane, composite membrane


The green hydrogen production through water electrolysis and the fuel fell received strong attention recently. The Proton Exchange Membrane Fuel Cell (PEMFC) and Proton Exchange Membrane Water Electrolysis (PEMWE) has advanced the most in rapid increase of electrochemical power system and green-hydrogen consumption demand. The polymer electrolyte membrane (PEM) is one of the key components of PEM-based devices which significantly influences the performance and durability of PEMFC and PEMWE systems. NafionTM is still considered one of the state-of-the-art (SoA) PEM membranes and in the market for 50 years plus, but water flooding, mechanical stability, unstable ion (Proton, H+) conductivity, and chemical degradation highly affect on stable performance and durability. Herein, we introduced advanced membranes, that resolved the drawbacks of SoA NafionTM membrane. First, our invented NafionTM-Plus is a hybridized NafionTM and nanostructured silsesquioxane (OSP), and the manufacturing process developed using an eco-friendly solvent [1, 2]. In brief, the mechanical stability and chemical stability of NafionTM-Plus are improved by 70% and 50% respectively and demonstrated 40% higher durability in PEMFC specific compared to the SoA NafionTM membrane. Compared to SoA NafionTM, NafionTM-Plus established 30% lower swelling ratio. In addition, NafionTM-Plus offers stable proton conductivity at elevated temperatures above 80 oC. The invented NafionTM-Plus offers peak power density of 1800 mW cm-2 at 80 oC and 100% RH, which is 90% higher than that of SoA NafionTM. The NafionTM-Plus membrane also showed better performance in water electrolysis setup as 2.25 V at 0.625 A cm-2 at room temperature. The second advancement is the modified PTFE/Nafion composite membrane prepared through a modified hydrophilic PTFE porous substrate and NafionTM polymer, which high proton conductivity enhanced mechanical property and chemical stability, and improved hydration properties than that of recently developed PTFE/Nafion membrane. The novel modified PTFE/Nafion MEA illustrated the maximum power density of 1670 mW cm-2 at 70 oC and 100% RH under H2/O2 conditions, which is 110% higher than that of unmodified PTFE/Nafion membrane. In addition, the performance reduction rate while reducing the relative humidity from 100% to 30% of modified PTFE/Nafion is 26.4%, which is 1.6-fold lower than that of Nafion membrane, indicating the moisture-retaining ability of modified PTFE/Nafion membrane. Both novel Nafion Plus and modified PTFE/Nafion offer significant performance in H2/air operation at different relative humidity, and both of these membranes show superiority over the state-of-the-art Nafion membrane, suggesting the promising candidacy in PEMFC and PEMWE.