Quantification of in situ temperature measurements on a PBI-based high temperature PEMFC unit cell

Lebæk, Jesper; Ali, Syed Talat; Møller, Per; Mathiasen, Claus; Nielsen, Lars; Kær, Søren Knudsen

doi:10.1016/j.ijhydene.2009.10.002

Cited by 29 publications

(6 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, for this type of FC there are some challenges which need to be solved, for example increased degradation rate at more demanding operating temperature [11][12][13]. Possible stressors for the operation of a HT-PEM FC are mass transfer limitation due to the presence of phosphoric acid in the catalyst layer [14,15], electrochemical cycling, the start/stop procedure, and fuel starvation [16].…”

Section: Introductionmentioning

confidence: 99%

Characterization methodology for anode starvation in HT-PEM fuel cells

Yezerska

Dushina²,

Liu³

et al. 2019

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

Degradation caused by fuel starvation may be an important reason for limited fuel cell lifetimes. In this work, we present an analytical characterization of the high temperature polymer exchange membrane fuel cell (HT-PEM FC) behavior under cycled anode starvation and subsequent regeneration conditions to investigate the impact of degradation due to H 2 starvation. Two membrane electrode assemblies (MEAs) with an active area of 21 cm 2 were operated of up to 550 minutes, which included up to 14 starvation / regeneration cycles. Overall cell voltage as well as current density distribution (S ++ unit) were measured simultaneously each minute during FC operation. The cyclicity of experiments was used to check the long term durability of the HT-PEM FC. After FC operation, micro-computed tomography (μ-CT) was applied to evaluate the influence of starvation on anode and cathode catalyst layer thicknesses.During starvation, cell voltage and current density distribution over the active area of the MEA significantly differed from nominal conditions. A significant drop in cell voltage from 0.6 to 0.1 V occured after approx. 20 minutes for the first starvation step, and after 10 minutes for all subsequent starvation steps. By contrast, the voltage response is immediately stable at 0.6 V during every regeneration step.During each starvation, the local current density reached up to 0.3 A•point -1 at the area near the gas inlet (9 cm 2 ) while near the outlet it drops to 0.01 A•point -1 . The deviation from a balanced current density distribution occurred after 10 minutes for the first starvation step, and after ca. 2 minutes for the subsequent starvation steps.Hence, compared to the voltage drop, the deviation from a balanced current density distribution always starts earlier. This indicates that the local current density distribution is more sensitive to local changes in the MEA than overal cell voltage drop. This finding may help to prevent undesirable influences of the starvation process.The μ-CT images showed that H 2 starvation lead to thickness decrease of ca. 20-30 % in both anode and cathode catalyst layers compared to a fresh MEA. Despite of the 14 starvation steps and the thinning of the catalyst layers the MEA presents stable cell voltage during regeneration.

show abstract

Section: Introductionmentioning

confidence: 99%

Characterization methodology for anode starvation in HT-PEM fuel cells

Yezerska

Dushina²,

Liu³

et al. 2019

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

show abstract

“…Phosphoric acid (PA) is widely employed as proton conductor at high-temperature operation conditions owing to its unique self-ionization, self-dehydration, and nonvolatile properties. − Because of the basic character of polybenzimidazole (PBI), which could yield strong acid–base interaction, PA-doped PBI membranes are considered as the most successful high-temperature PEMs over the past decades. − Nevertheless, these properties might not directly be applied to other aromatic PEMs, such as SPAES, SPEEK, and SPP. The reason for this has to do with the neutral or even acidic character of the molecules.…”

Section: Introductionmentioning

confidence: 99%

Poly(2,5-benzimidazole)-Grafted Graphene Oxide as an Effective Proton Conductor for Construction of Nanocomposite Proton Exchange Membrane

Qiu

Ueda

et al. 2017

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

To improve proton conduction properties of conventional sulfonated poly(ether ether ketone) (SPEEK), poly(2,5-benzimidazole)-grafted graphene oxide (ABPBI-GO) was prepared to fabricate nanocomposite membranes, which then were further doped with phosphoric acid (PA). The ABPBI-GO was synthesized through the reaction of 3,4-diaminobenzoic acid with the carboxyl acid groups present on the GO surface. The simultaneous incorporation of ABPBI-GO and PA into SPEEK did not only improve the physicochemical performance of the membranes in terms of thermal stability, water uptake, dimensional stability, proton conductivity, and methanol permeation resistance but also relieve PA leaching from the membranes though acid-base interactions. The resulting composite membranes exhibited enhanced proton conductivities in extended humidity ranges thanks to the hygroscopic character of PA and the increased water uptake. Moreover, the unique self-ionization, self-dehydration, and nonvolatile properties of PA improved the high-temperature proton conductivities (σ) of PA-doped membranes. The PA-doped SPEEK/ABPBI-GO-3.0 delivered a σ of 7.5 mS cm at 140 °C/0% RH. This value was fourfold higher than that of pristine SPEEK membranes. The PA-doped SPEEK/ABPBI-GO-3.0 based fuel cell membranes delivered power densities of 831.06 and 72.25 mW cm at 80 °C/95% RH and 120 °C/0% RH, respectively. By contrast, the PA-doped SPEEK membrane generated only 655.63 and 44.58 mW cm under the same testing conditions.

show abstract

“…But the microstructures of In2O3 were changed significantly under air annealing. The organization grains of In2O3 became denser and larger, and the cellular crystals were formed at 1000 °C, implying that the oxygen entered the thin film structure at 1000 °C air annealing, and the oxygen occupied the oxygen vacancy of the In2O3 films, making the conductive electrons in the In2O3 film decrease rapidly according to the Equation (3). As a result, the Seebeck coefficient of In2O3 increased.…”

Section: Resultsmentioning

confidence: 97%

“…The accurate measurement of high temperature is particularly important in modern science. With the development of MEMS technology, TFTCs are widely used in many areas [1][2][3][4]. TFTCs have many advantages, such as fast response, high measurement accuracy, and easy integration [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Effect of Annealing on the Thermoelectricity Properties of the WRe26-In2O3 Thin Film Thermocouples

et al. 2020

View full text Add to dashboard Cite

WRe26-In2O3 (WRe26 (tungsten-26% rhenium) and In2O3 thermoelectric materials) thin film thermocouples (TFTCs) have been fabricated based on magnetron sputtering technology, which can be used in temperature measurement. Many annealing processes were studied to promote the sensitivity of WRe26-In2O3 TFTCs. The optimal annealing process of the thermocouple under this kind of RF magnetron sputtering method was proposed after analyzing the properties of In2O3 films and the thermoelectric voltage of TFTCs at different annealing processes. The calibration results showed that the WRe26-In2O3 TFTCs achieved a thermoelectric voltage of 123.6 mV at a temperature difference of 612.9 K, with a sensitivity of up to 201.6 µV/K. Also, TFTC kept a stable thermoelectric voltage output at 973 K for 20 min and at 773 K for two hours. In general, the WRe26-In2O3 TFTCs developed in this work have great potential for practical applications. In future work, we will focus on the thermoelectric stability of TFTCs at higher temperatures.

show abstract

Quantification of in situ temperature measurements on a PBI-based high temperature PEMFC unit cell

Cited by 29 publications

References 17 publications

Characterization methodology for anode starvation in HT-PEM fuel cells

Characterization methodology for anode starvation in HT-PEM fuel cells

Poly(2,5-benzimidazole)-Grafted Graphene Oxide as an Effective Proton Conductor for Construction of Nanocomposite Proton Exchange Membrane

Effect of Annealing on the Thermoelectricity Properties of the WRe26-In2O3 Thin Film Thermocouples

Contact Info

Product

Resources

About