Mechanistic analysis of coupled humidification, backpressure, and cathode stoichiometry effects in HT-PEMFCs

Todorovski, Filip (avtor), Todorovski, Emilija (avtor), Kravos, Andraž (avtor), Katrašnik, Tomaž (avtor), Sekavčnik, Mihael (avtor), Mori, Mitja (avtor), Lotrič, Andrej (avtor)

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) based on phosphoric-acid-doped polybenzimidazole membranes are promising for reformate-fed systems, yet their performance is highly sensitive to system operating parameters. This study evaluates the influence of cathode stoichiometry (λ▫$_{air}$▫=1.8–2.5), reactant backpressure (0.0–2.0 barg at the anode and 0.0–1.8 barg at the cathode), and 5 % inlet humidification at 160 °C using polarization analysis combined with electrochemical impedance spectroscopy (EIS), distribution of relaxation times (DRT), Kramers–Kronig validation, and Monte-Carlo uncertainty quantification. Relative to dry atmospheric operation (0.0 barg, 0 % RH), increasing backpressure reduces transport-related resistance by up to 43 % at λ▫$_{air}$▫=1.8 and 59 % at λ▫$_{air}$▫=2.5 (0.4 A/cm²). In contrast, introducing 5 % RH at atmospheric pressure increases mass transport resistance by approximately 36 % (λ▫$_{air}$▫=1.8) and 63 % (λ▫$_{air}$▫=2.5), while KK residuals increase by up to 48 % and 24 %, respectively. A Unified Operating Index (UOI) integrating voltage, resistance, and stability was developed to rank operating regimes. At 0.8 A/cm², λ▫$_{air}$▫=1.8 and 2.0–1.8 barg, humidification lowers the UOI by 75.8 % relative to dry operation (amplification factor ≈13.5). Increasing stoichiometry to λ▫$_{air}$▫=2.5 lowers this effect by ∼50 % under identical conditions but does not eliminate instability. Dry operation with higher stoichiometry and moderate backpressure provides the most suitable operating window.

• Jezik: Angleški jezik
• Ključne besede: high-temperature PEM fuel cell, distribution of relaxation times, cathode stoichiometry, reactants backpressure, reactants relative humidity
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2026
• Št. strani: 20 str.
• Številčenje: Vol. 569, art. 148933
• PID: 20.500.12556/RUL-182193
• UDK: 621.352.6:539.125.4:662.611.2
• ISSN pri članku: 0013-4686
• DOI: 10.1016/j.electacta.2026.148933
• COBISS.SI-ID: 276710659
• Datum objave v RUL: 29.04.2026

Gradivo je del revije

• Naslov: Electrochimica acta
• Skrajšan naslov: Electrochim. acta
• Založnik: Elsevier
• ISSN: 0013-4686
• COBISS.SI-ID: 1106959

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: visokotemperaturne gorivne celice, protonska izmenjevalna membrana, porazdelitev relaksacijskih časov, stehiometrija katode, protitlak reaktantov, relativna vlažnost reaktantov