Fabrication and functional testing of hot-pressed bifunctional gas-diffusion electrodes for zinc-air batteriesAlleva, Alessandro (Korespondenčni avtor) Gianoncelli, Alessandra (Avtor) Kourousias, George (Avtor) Guzzi, Francesco (Avtor) Coppens, Frederik (Avtor) Mancini, Lucia (Avtor) Bonanni, Valentina (Avtor) Marini, Emanuele (Avtor) Martinelli, Giacomo (Avtor) Bozzini, Benedetto (Avtor) zinc-air batterygas diffusion electrodetomographydegradationSTXMThe study presents the fabrication, electrochemical testing, and characterization based on hyperspectral soft-X ray imaging and hard X-ray computed microtomography of novel gas diffusion electrodes (GDEs) for alkaline rechargeable zinc-air batteries (ZABs). α-MnO2 nanowires and Ni/NiO core-shell nanoparticles (NPs) were employed as Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) electrocatalysts. In order to achieve high catalyst loading and reduce fabrication times, the GDEs were fabricated by hot-pressing. The electrochemical functional testing of the GDEs was carried out with a rapid screening protocol (RSP) as well as with prolonged galvanostatic discharge-charge cycling (GCDC) under realistic operating conditions. Hot-pressed MnO2-based GDEs with loadings in the range 17 ± 0.9 mg cm-2 exhibit high stability and low ORR and OER overpotentials compared with the literature state-of-the-art. In contrast, MnO2/Ni-GDEs, fabricated with the same approach, are not as effective, owing to subtle architectural changes induced by addition of Ni/NiO NPs. This observation triggered in depth investigation of the architecture-function relationship for the fabrication approach considered. Specifically, X-ray micro-computed tomography disclosed clustering of Ni NPs leading to OER localization inside the active-layer (AL), in turn causing AL delamination. In addition, chemical-state mapping based on soft-X ray absorption hyperspectral micro-imaging revealed that MnO2-GDEs retain a higher proportion of electrochemically active Mn(III) and Mn(IV), when compared with GDEs of similar composition, but fabricated by spray coating in previous work in our group. Moreover, we found that the hot-pressing mitigates carbothermal reduction of α-MnO2, that unbalances the electrocatalytic blend of Mn chemical states.Elsevier20262026-05-19 08:36:03Neznano29433UDK: 544.5/.6ISSN pri članku: 1873-3859DOI: 10.1016/j.electacta.2026.148851COBISS_ID: 277048579sl