Electrocatalyst Stability In PEMFCs And The Role Of Fuel Starvation And Cell Reversal Tolerant Anodes

Ralph, T. R.; Hudson, Sarah L.; Wilkinson, David P.

doi:10.1149/1.2214545

Cited by 78 publications

(56 citation statements)

References 6 publications

(15 reference statements)

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“…Considering that the RH in tests 1, 4, and 7 was the lowest level, 40%, the low humidity condition was considered to affect the moisture content of the proton exchange membrane. A dry proton exchange membrane could not drag enough protons to participate in the electrochemical reaction, thereby increasing the ohmic loss . In addition, the activation impedance of the cathode corresponding to each group was greater than the activation impedance of the anode, indicating that the cathode activation loss occupied a more prominent position.…”

Section: Resultsmentioning

confidence: 99%

Parameter optimization of PEMFC stack under steady working condition using orthogonal experimental design

et al. 2018

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Summary Operating parameters have a huge impact on the output characteristics of a proton exchange membrane fuel cell stack. In this study, to optimize the performance of proton exchange membrane fuel cell stack, 4 sets of operating parameters, which include working temperature, cathode stoichiometric, relative humidity, and backpressure, were optimized by means of the orthogonal experimental design. The experiment was developed with the help of 4‐factor and 3‐level orthogonal table. Nine orthogonal experiments were performed, and the polarization curve, local current density distribution, and electrochemical impedance spectroscopy of each experiment were obtained. It is observed that cathode stoichiometric and working temperature have much stronger effects on the output voltage and output consistency of stack than that of relative humidity and backpressure. Using comprehensive equilibrium method, the optimized combination of each parameter was achieved as follows: the working temperature was 75°C, cathode stoichiometric was 2.5, relative humidity was 50%, and backpressure was 1 bar. The on‐site test result showed that when the cathode stoichiometric was low, and some part of the stack would be in a starvation condition and when the temperature was low, it might cause mass transfer problems.

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Section: Resultsmentioning

confidence: 99%

Parameter optimization of PEMFC stack under steady working condition using orthogonal experimental design

et al. 2018

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“…Therefore, it can be inferred that the uneven distribution of the flow rate of each cell in the PEMFC stack is the cause of the cell voltage abnormality. Uneven pressure drops among cells can alter the gas distribution in a PEMFC stack . The anode channel will be blocked by flooding water or stack material debris.…”

Section: Resultsmentioning

confidence: 99%

“…Uneven pressure drops among cells can alter the gas distribution in a PEMFC stack. 41 The anode channel will be blocked by flooding water or stack material debris. This may be the reason for the uneven distribution of gas inside the PEMFC stack.…”

Section: Performance Of the Pemfc Stackmentioning

confidence: 99%

Experimental study and mitigation of abnormal behavior of cell voltage in a proton exchange membrane fuel cell stack

Luo

Jian

2019

Int J Energy Res

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Summary The aim of this study is to investigate the abnormal behavior of cell voltage in a proton exchange membrane fuel cell stack and a mitigation strategy. The proposed strategy is simple and requires only a three‐way solenoid valve to replace the direct way solenoid valve of the original system. It is applied to a proton exchange membrane fuel cell stack with a dead‐ended anode to verify its validity. The behavior of the cell voltages in the stack is discussed in detail, especially the cell reversal process. The results show that the proposed strategy can significantly reduce the severity of hydrogen starvation. And the maximum power of the stack is increased by 10.67%. It is a sudden increase related to cell reversal mitigation. Uneven hydrogen distribution is the cause of low cell voltage and cell reversal. This strategy increases the cell voltage by increasing the hydrogen content in the anode flow channel downstream. It also significantly reduces the fluctuations in cell voltage and improves the uniformity of the cell voltage. This experimental study contributes to mitigate hydrogen starvation in cells of proton exchange membrane fuel cell stacks in application.

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“…On the contrary, negative current density appears close to the air outlet and the lowest value reaches –147 mA cm −2 . Ralph et al reveals that the reversal current appears because the oxygen permeates to the anode through the electrolyte membrane, when the hydrogen fuel is locally insufficient in the anode during PEMFC operation. As a result, the H 2 /air boundary is formed and leads to rapid carbon corrosion on the corresponding cathode side according to the following oxidation equation (COR) Eq.…”

Section: Resultsmentioning

confidence: 99%

Comparison Between the Constant Dummy Load and Step Load Shut‐Down Strategy for PEMFCs

et al. 2018

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Carbon corrosion of catalyst layer (CL) caused by start‐up/shut‐down (SU/SD) conditions in proton exchange membrane fuel cells (PEMFCs) decreases the durability of the membrane electrode assembly (MEA). It is reported that the dummy load shut‐down strategy helps alleviating the carbon corrosion. In this paper, constant load strategy and step load strategy are applied during 900 SU/SD cycles each, to investigate the effects of different dummy load forms on the durability of PEMFC. Reversal current is observed during the last phase of 5 A constant loading process, while there is no reversal current during the step load strategy. The results obtained through polarization curves, cyclic voltammetry (CV) and scanning electron microscope (SEM) technologies, prove the step load strategy more efficient to alleviate the performance decay. Therefore, the step load strategy can improve the durability of PEMFC.

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Electrocatalyst Stability In PEMFCs And The Role Of Fuel Starvation And Cell Reversal Tolerant Anodes

Cited by 78 publications

References 6 publications

Parameter optimization of PEMFC stack under steady working condition using orthogonal experimental design

Parameter optimization of PEMFC stack under steady working condition using orthogonal experimental design

Experimental study and mitigation of abnormal behavior of cell voltage in a proton exchange membrane fuel cell stack

Comparison Between the Constant Dummy Load and Step Load Shut‐Down Strategy for PEMFCs

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