The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power...The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this paper,we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water management approach is based on water vapor feeding in the hydrogen electrode,and water evaporation in the iron electrode,thus enabling the high current density operation of 300 mA cm^(-2).展开更多
This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane(PEM)fuel cell stack of 1 k W.The model incorporates major electric and thermodynamic variables and p...This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane(PEM)fuel cell stack of 1 k W.The model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEM fuel cell under different operational conditions.Influence of each of these parameters and variables upon the operation and the performance of the PEM fuel cell are investigated.The mathematical equations are modeled by using Matlab-Simulink tools in order to simulate the operation of the developed model with a commercial available 1kW horizon PEM fuel cell stack(H-1000),which is used for the purposes of model validation and tuning of the developed model.The model can be extrapolated to higher wattage fuel cells of similar arrangements.New equation is presented to determine the impact of using air to supply the PEM fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it.展开更多
基金support primarily from the U.S.Department of Energy Advanced Research Projects Agency-Energy 2015 OPEN program under Contract No.67995support by Energy Storage Materials Initiative(ESMI),which is a Laboratory Directed Research and Development Project at Pacific Northwest National Laboratory(PNNL).PNNL is a multiprogram national laboratory operated for the U.S.Department of Energy(DOE)by Battelle Memorial Institute under Contract no.DE-AC05-76RL01830.
文摘The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this paper,we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water management approach is based on water vapor feeding in the hydrogen electrode,and water evaporation in the iron electrode,thus enabling the high current density operation of 300 mA cm^(-2).
文摘This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane(PEM)fuel cell stack of 1 k W.The model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEM fuel cell under different operational conditions.Influence of each of these parameters and variables upon the operation and the performance of the PEM fuel cell are investigated.The mathematical equations are modeled by using Matlab-Simulink tools in order to simulate the operation of the developed model with a commercial available 1kW horizon PEM fuel cell stack(H-1000),which is used for the purposes of model validation and tuning of the developed model.The model can be extrapolated to higher wattage fuel cells of similar arrangements.New equation is presented to determine the impact of using air to supply the PEM fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it.
