Towards developing a backing layer for proton exchange membrane electrolyzers

Lettenmeier, Philipp; Kolb, Svenja; Burggraf, Fabian; Gago, Aldo; Friedrich, K. Andreas

doi:10.1016/j.jpowsour.2016.01.100

Cited by 124 publications

(154 citation statements)

References 17 publications

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“…The measurements reveal that the contact between the carbon BPP on the cathode side and the the respective CD accounts for the highest share. Somewhat surprisingly, the cell under investigation here does not show a significant contribution of the anodic PTL (Ti felt) as found by other studies [45]. The reason may be the incorporated Ir metal layer between the CL and the PTL on the anode, which is a relatively unique feature.…”

Section: Contact Resistancessupporting

confidence: 63%

Model-supported characterization of a PEM water electrolysis cell for the effect of compression

Frensch

Olesen

Araya

et al. 2018

Electrochimica Acta

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This paper investigates the influence of the cell compression of a PEM water electrolysis cell. A small single cell is therefore electrochemically analyzed by means of polarization behavior and impedance spectroscopy throughout a range of currents (0.01 A cm −2 to 2.0 A cm −2 ) at two temperatures (60• C and 80• C) and eight compressions (0.77 MPa to 3.45 MPa). Additionally, a computational model is utilized to support the analysis. The main findings are that cell compression has a positive effect on overall cell performance due to decreased contact resistances, but is subject to optimization. In this case, no signs of severe mass transport problems due to crushed transport layers are visible in either polarization curves or impedance plots, even at high currents. However, a Tafel plot analysis revealed more than one slope throughout the current range. The change in the Tafel slope is therefore discussed and connected to the electrochemical reaction or an ohmic contribution from a non-electrode component.

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Section: Contact Resistancessupporting

confidence: 63%

Model-supported characterization of a PEM water electrolysis cell for the effect of compression

Frensch

Olesen

Araya

et al. 2018

Electrochimica Acta

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“…These findings in the combination with the fact that an increase in -Z im are observed at the highest frequencies in all the Nyquist plots, cause us to suggest that a third suppressed arc independent on current density is partly observed at the highest frequencies probably originating from current constrictions as described by Fleig et al 27 Lettenmeier et al 6 observed the same trend with a very high frequency EIS arc independent on current density. Porous nature of the anode or areas with extended electrolyte-electrode contact, causing two-phase boundaries instead of triple phase boundaries in the anode material, may prevent the proton conduction in parts of the electrolyte surface increasing the resistance of the electrolyte.…”

Section: Discussionsupporting

confidence: 71%

“…[4][5][6][7][8][9][10][11][12] However, some research groups such as Rozain et al, 13,14 Lettenmeier et al 15 and Siracusano et al 5,16 among others have studied EIS of PEMECs in further detail, but most often at low current densities in the activation region of the iV-curve, where the oxygen evolution reaction (OER) current density is very low. [5][6][7][8]13,14,16,17 Only a few research groups have reported EIS measured at higher current densities in the linear region of the iV-curve during the OER. [6][7][8] The EIS data is often fitted to an empirical equivalent circuit consisting of a serial resistance and one or two arcs reported to originate from the anode, or from the cathode and the anode.…”

mentioning

confidence: 99%

“…[5][6][7][8]13,14,16,17 Only a few research groups have reported EIS measured at higher current densities in the linear region of the iV-curve during the OER. [6][7][8] The EIS data is often fitted to an empirical equivalent circuit consisting of a serial resistance and one or two arcs reported to originate from the anode, or from the cathode and the anode. Sometimes diffusion elements are added to the equivalent circuit as well.…”

mentioning

confidence: 99%

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Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Elsøe

Grahl‐Madsen

Scherer³

et al. 2017

J. Electrochem. Soc.

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In this study, electrochemical impedance spectroscopy (EIS) is applied in combination with cyclic voltammetry (CV) and current density -cell voltage curves (iV-curves) to investigate the processes contributing to the total impedance of a polymer electrolyte membrane electrolysis cell (PEMEC). iV-curves were linear above 0.35 A cm −2 implying ohmic processes to be performance limiting, however the impedance spectra showed three arcs indicating three electrochemical reactions at these conditions not to be purely ohmic, but also to have capacitive properties. A hypothesis that the composite IrO x /Nafion anode catalyst layer causes two of these arcs with a constant sum of resistance and current constrictions cause the third arc, is suggested. This hypothesis implies that the total differential cell resistance at current densities above 0.35 A cm −2 is purely ascribed to protonic resistance in Nafion in this type of PEMEC. The interest in renewable electrical energy obtained from e.g. wind turbines and solar cells have increased over the past years. However, the demand of electrical energy from society does not always correlate with the renewable electrical energy production, and a method to store the excess electrical energy for later use is needed. One such method is electrolysis of water into hydrogen and thus converts electrical energy into chemical energy bound in the hydrogen molecules, and thereby the energy can be stored. PEMECs have the ability to operate at high current densities, which reduces the operation costs.

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“…Because the differences in HFR cannot be explained by the PTL bulk properties, it is hypothesized that the different SSD results in different interfacial contact resistances (ICRs) between PTLs and CLs. ICRs may be quantified using ex situ methods, 37 as demonstrated for PEWE PTLs by Lettenmeier et al 38 who reported a reduction in the ICR of about 20 m · cm 2 when adding a microporous layer (MPL) to the PTL (also T10).…”

Section: Overpotential Analysis-the Cell Voltage Is Composed Of the mentioning

confidence: 99%

Influence of Operating Conditions and Material Properties on the Mass Transport Losses of Polymer Electrolyte Water Electrolysis

Suermann

Takanohashi

Lamibrac

et al. 2017

J. Electrochem. Soc.

110

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Three different porous transport layer (PTL) structures, based on titanium sintered powders, were characterized using X-ray tomographic microscopy to determine key geometric properties such as porosity, pore and particle size distributions as well as effective transport properties. The mass transport through the PTL contributes to the voltage losses in the polymer electrolyte water electrolysis cell. Therefore, influence of the PTL structure on the mass transport overpotential is investigated as function of current densities (≤ 4 A · cm −2 ), operating pressures (1-100 bar) and temperatures (40-60 • C), respectively. A decrease of transport losses was observed with increasing pressure and temperature for all investigated PTLs. At around 100 bar balanced pressure, the transport losses for all PTLs converge to about 40 mV per applied A · cm −2 , suggesting that other parts of the cell such as the catalyst layer or their interface contribute to these remaining losses. The performance loss, induced by the different PTL structures, shows a stronger correlation with geometric parameters such as pore and particle size distributions than transport properties like effective diffusivity and permeability. The finest materials with d 50 pore and particle diameters of 40-48 and 68 μm, respectively, are performing better than the coarsest material with diameters roughly twice the sizes. Polymer electrolyte water electrolysis (PEWE) is a promising technology to convert (surplus) electric energy into chemical energy in form of hydrogen to avoid curtailment of the fluctuating renewable electricity sources 1 and thus reducing the need of fossil fuels. 2 Depending on the use of hydrogen, the gas has to be provided at pressure levels up to 1000 bar, i.e. for the use in mobility applications.3 Commercial electrolyzers are operated at pressures in the order of 30 bar (hydrogen and optionally oxygen) 4 to reduce downstream compression and drying efforts. 5For energy applications, high efficiency of the electrolysis conversion process is a key property. As in any electrochemical cell, also with PEWE, losses/overpotentials incur when a current is passed. Ohmic and kinetic overpotentials, related to the movement of protons in the polymer electrolyte and the finite rates of the electrochemical reactions are reasonably well understood for PEWE. [6][7][8] In most cases, at least at current densities above about 1 A · cm −2 , losses in addition to ohmic and kinetic sources are observed and related to mass transport resistances in the porous structures of the catalyst and porous transport layers (PTLs), though their nature and origin in PEWE are not well understood.6 Nevertheless, as long as a sufficient water supply is guaranteed, no transport limitations occur in the form of a turning point in the current/voltage characteristics (i/E-curves), as demonstrated by Lewinski et al. 9 up to 19 A · cm −2 . In polymer electrolyte fuel cells (PEFC), a technology similar to PEWE, the effect of mass transport in the micro-porous structures of the el...

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Towards developing a backing layer for proton exchange membrane electrolyzers

Cited by 124 publications

References 17 publications

Model-supported characterization of a PEM water electrolysis cell for the effect of compression

Model-supported characterization of a PEM water electrolysis cell for the effect of compression

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

Influence of Operating Conditions and Material Properties on the Mass Transport Losses of Polymer Electrolyte Water Electrolysis

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