High-Performance Bipolar Membrane Development for Improved Water Dissociation

Abstract

Bipolar membranes (BPMs) are the enabling component of many promising electrochemical devices used for separation and energy conversion. Here, we describe the development of high-performance BPMs, including two-dimensional BPMs (2D BPMs) prepared by hot-pressing two preformed membranes and three-dimensional BPMs (3D BPMs) prepared by electrospinning ionomer solutions and polyethylene oxide. Graphene oxide (GO x ) was introduced into the BPM junction as a water-dissociation catalyst. We assessed electrochemical performance of the prepared BPMs by voltage–current (V–I) curves and galvanostatic electrochemical impedance spectroscopy. We found the optimal GO x loading in 2D BPMs to be 100 μg cm–2, which led to complete coverage of GO x at the interface. The integration of GO x beyond this loading moderately improved electrochemical performance but significantly compromised mechanical strength. GO x -catalyzed 2D BPMs showed comparable performance with a commercially available Fumasep BPM at current densities up to 500 mA cm–2. The 3D BPMs exhibited even better performance: lower resistance and higher efficiency for water dissociation and substantially higher stability under repeated cycling up to high current densities. The improved electrochemical performance and mechanical stability of the 3D BPMs make them suitable for incorporation into CO2 electrolysis devices where high current densities are necessary.

Orientation of a bipolar membrane determines the dominant ion and carbonic species transport in membrane electrode assemblies for CO2 reduction

“…Because our membrane was chosen to allow synthesis in dry state, this particular commercial BPM is not optimized for CO 2 reduction in this configuration. Recent literature has shown via experimental work [27][28][29] and simulations 30,31 that the catalyst overpotential can be easily reduced by two orders of magnitude at these current densities compared to the one that was used for these studies. Hence, the cathode potential in Figure 2e-f is expected much closer to its thermodynamic equivalent in an optimized BPMEA system.…”

Process Parameters in the Electrochemical Reduction of Carbon Dioxide to Ethylene

“…The high electric field at the junction permits the dissociation of water at significantly higher rates than in the absence of an electric field. The rate of water dissociation in a catalyst‐loaded bipolar membrane junction is significantly faster, up to 50 million times greater than in aqueous solution 203. In the presence of an electric field, water dissociation in the junction of a bipolar membrane occurs at lower potentials, ≈0.8 V vs 1.23 V, than can be achieved using conventional electrolysis 204.…”

“…The operating conditions are important, as excessive current densities can result in irreversible damage including blistering and delamination at the junction 203. Although recent works using 3‐dimensionally interlocked fiber junction interfaces have shown short term stability at higher current densities, commercial 2‐dimensional membranes are currently limited to about 100 mA cm −2 to prevent blistering and irreversible damage 204.…”

Application of Electrospun Nanofibers for Fabrication of Versatile and Highly Efficient Electrochemical Devices: A Review

“…Recently, Chen et al used electrospun polyethylene oxide (PEO)/ionomer/graphene oxide (GO) nanofiber mats for water dissociation and found high stability under repeated cycling, even for high current densities. These findings let the authors suggest such three-dimensional bipolar membranes for the application in CO 2 electrolysis devices where high current densities are applied [ 72 ].…”