Stabilizing the Catalyst Layer for Durable and High Performance Alkaline Membrane Fuel Cells and Water Electrolyzers

Anion exchange membrane (AEM) fuel cells (AEMFCs) and water electrolyzers (AEMWEs) suffer from insufficient performance and durability compared with commercialized energy conversion systems. Great efforts have been devoted to designing high-quality AEMs and catalysts. However, the significance of the stability of the catalyst layer has been largely disregarded. Here, an in situ cross-linking strategy was developed to promote the interactions within the catalyst layer and the interactions between catalyst layer and AEM. The adhesion strength of the catalyst layer after cross-linking was improved 7 times compared with the uncross-linked catalyst layer due to the formation of covalent bonds between the catalyst layer and AEM. The AEMFC can be operated under 0.6 A cm–2 for 1000 h with a voltage decay rate of 20 μV h–1. The related AEMWE achieved an unprecedented current density of 15.17 A cm–2 at 2.0 V and was operated at 0.5, 1.0, and 1.5 A cm–2 for 1000 h.


Figure S4 .
Figure S4.The gel fractions of Trip-PFBP-m and PDTP-Pr-m membranes with different thermal treatment times.

Figure S5 .
Figure S5.The crosslinking degree of x−PDTP-Pr-50 membranes with different thermal treatment times.a) FT-IR spectra of x-PDTP-Pr-50 with different thermal treatment times.b) The propargyl group remaining of the x-PDTP-Pr-50 membrane with different thermal treatment times calculated by integration of propargyl groups in the FT-IR spectra.

Figure S7 .
Figure S7.The water uptake and swelling ratio of crosslinked x-PDTP-Pr-x and x-Trip-PFBP-Pr-x membranes.a) The water uptake and b) swelling ratio of x-PDTP-Pr-m and x-Trip-PFBP-Pr-m membranes in OH -form at 30 °C after thermal treatment of 0, 120, and 240 min.

Figure S9 .
Figure S9.Hydroxide conductivity of a) x-PDTP-Pr-m and b) x-PFBP-Pr-m membranes after thermal treatment of 120 min.

Figure S10 .
Figure S10.Ohmic resistance of a) x-PDTP-Pr-m and b) x-PFBP-Pr-m as a function of temperatures

Figure S12 .
Figure S12.The SEM cross-sectional image of the MEA for the peeling-off measurement.

Figure S15 .
Figure S15.Crosslinked models via MD simulation and the interaction energies between the ionomer and AEM layers, as well as the ionomer layers themselves.a) In the crosslinked models, the density fields of the crosslinked sites are displayed in orange and green colors, which indicate the poorer and richer regions of the crosslinked sites, respectively.Also, atoms in the crosslinked site are displayed and the other atoms are hidden for clarity.As the models with a conversion rate of 0% indicate the non-crosslinked models, there is no density field inside the model, and empty boxes are displayed.b) The energies of valence bonding interactions were calculated using the difference of the valence bonding energy contribution in the potential energy of the fully combined layer model (ionomer layer + AEM layer) and the summation of the valence energy contribution of each layer.

Figure S17 .
Figure S17.The catalyst layer stability measurement.a) The schematic diagram of ionomer effluent from MEA after treatment in 1 M NaOH solution at room temperature for 24 h and in deionized water at 80°C for 24 h.b) The UV absorption of the effluent from MEA.The adsorption in 300 nm is associated with aromatic units from ionomers.