화학공학소재연구정보센터
Journal of Power Sources, Vol.423, 192-202, 2019
Graphene and reduced graphene oxide based microporous layers for high-performance proton-exchange membrane fuel cells under varied humidity operation
Cathode microporous layers (MPLs) play an important role in the performance of proton exchange membrane (PEM) fuel cells through two-phase flow and interfacial effects. In this study, alternative graphene-based MPLs are developed and characterized by ex-situ methods and fuel cell polarization experiments at 100% and 20% cathode relative humidity (RH). The studied MPLs include: graphene (GN), reduced graphene oxide (RGO), graphite (GR) and their composites with conventional carbon black (CB). GN and RGO promote interfacial contact and adhesion to the catalyst layer (CL). These MPLs show improved kinetic and ohmic polarization compared to CB, but limit oxygen gas transport at 100% RH due to excessive water retention. The addition of CB to create composite MPLs, however, mitigates water retention near the CL by capillary suction. Hence, maximum power densities improve by 68% and 22% compared to the original GN and RGO MPLs, and is also 28% higher for the GN + CB MPL than for the CB MPL alone. At 20% RH, the graphene-composite MPLs demonstrate remarkable performance preservation (1.4 mV h(-1) voltage decrease for GN + CB vs. 464 mV h(-1) for CB at 1000 mA cm(-2)). Through extensive physical and performance evaluations, this study provides a comprehensive understanding of how graphene materials behave in MPLs under varied humidity.