Renewable Hydrogen and Electricity Dispatch with Multiple Ni–Fe Electrode Storage

Weninger, Bernhard M H; Mulder, Fokko M.

doi:10.1021/acsenergylett.8b02488

Cited by 17 publications

(18 citation statements)

References 16 publications

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“…During discharging, the iron electrode is oxidized, while the nickel counter electrode now produces hydrogen. Equations 10 – 12 7 provide the overall system equations for the first discharge plateau of iron and the nickel-wire counter electrode. The half-reactions for discharging (10, E cell = −0.05 V), recharging (11, E cell = 1.28 V), and overcharging (12, E 0 = 1.23 V) combined give the cell reactions Galvanostatic electrochemical experiments were executed with a Parstat MC 2000A Module.…”

Section: Methodsmentioning

confidence: 99%

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Neutron Diffraction Study of a Sintered Iron Electrode In Operando

Weninger

Thijs

Nijman³

et al. 2021

J. Phys. Chem. C

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Iron is a promising, earth-abundant material for future energy applications. In this study, we use a neutron diffractometer to investigate the properties of an iron electrode in an alkaline environment. As neutrons penetrate deeply into materials, neutron scattering gives us a unique insight into what is happening inside the electrode. We made our measurements while the electrode was charging or discharging. Our key questions are: Which phases occur for the first and second discharge plateaus? And why are iron electrodes less responsive at higher discharge rates? We conclude that metallic iron and iron hydroxide form the redox pair for the first discharge plateau. For the second discharge plateau, we found a phase similar to feroxyhyte but with symmetrical and equally spaced arrangement of hydrogen atoms. The data suggest that no other iron oxide or iron (oxy)hydroxide formed. Remarkable findings include the following: (1) substantial amounts of iron hydroxide are always present inside the electrode. (2) Passivation is mostly caused by iron hydroxide that is unable to recharge. (3) Iron fractions change as expected, while iron hydroxide fractions are delayed, resulting in substantial amounts of amorphous, undetectable iron phases. About 40% of the participating iron of the first plateau and about 55% of the participating iron for the second plateau are undetectable. (4) Massive and unexpected precipitation of iron hydroxide occurs in the transition from discharging to charging. (2), (3), and (4) together cause accumulation of iron hydroxide inside the electrode.

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Section: Methodsmentioning

confidence: 99%

“… 3 − 6 Iron electrodes have recently been proposed as means to decouple oxygen and hydrogen generation. 7 − 10 To do so, the iron electrode is located in between the cathode and the anode to delay hydrogen generation. The resulting system can release its stored energy electrically or as hydrogen.…”

Section: Introductionmentioning

confidence: 99%

Neutron Diffraction Study of a Sintered Iron Electrode In Operando

Weninger

Thijs

Nijman³

et al. 2021

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

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“…However, self-discharge tests were not carried out to confirm or refute this theory. Self-discharge does not necessarily result in a high rate of energy loss, since it can result in the release of hydrogen and oxygen gases (Weninger and Mulder, 2019). The production of gases during the charging process was not measured during the long capacity tests, but was measured in the combined chargingelectrolysis tests described in Charge Efficiency During Electrolysis Tests, Energy Efficiency During Full Charging…”

Section: Cell Capacitymentioning

confidence: 99%

Characterisation of a Nickel-iron Battolyser, an Integrated Battery and Electrolyser

2020

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Electricity systems require energy storage on all time scales to accommodate the variations in output of solar and wind power when those sources of electricity constitute most, or all, of the generation on the system. This paper builds on recent research into nickel-iron battery-electrolysers or “battolysers” as both short-term and long-term energy storage. For short-term cycling as a battery, the internal resistances and time constants have been measured, including the component values of resistors and capacitors in equivalent circuits. The dependence of these values on state-of-charge and temperature have also been measured. The results confirm that a nickel-iron cell can hold 25% more than its nominal charge. However, this increased capacity disappears at temperatures of 60°C and may be dissipated quickly by self-discharge. When operating as an electrolyser for long-term energy storage, the experiments have established the importance of a separation gap between each electrode and the membrane for gas evolution and established the optimum size of this gap as approximately 1.25 mm. The nickel-iron cell has acceptable performance as an electrolyser for Power-to-X energy conversion but its large internal resistance limits voltage efficiency to 75% at 5-h charge and discharge rate, with or without a bubble separation membrane.

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“…Recently, we have thus seen materials and concepts originating from battery technology being applied to new WE devices, leading to some of those being labelled battolysers. 13,14 While such potentially synergistic merging of concepts is exciting at a fundamental level, its practicality requires a critical evaluation which must be made in light of past and current developments of more ma-ture WEs technologies. This perspective thus briefly recalls the fundamental differences between architecture and design of batteries and WEs, and more specifically why their transpositions from lab-scale discoveries to industrial-scale setup are very different.…”

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confidence: 99%

Water electrolysers with closed and open electrochemical systems

2020

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Green hydrogen production using renewables-powered, low-temperature water electrolysers is crucial for rapidly decarbonising the industrial sector and with it many chemical transformation processes. However, despite decades of research, advances at laboratory-scale in terms of catalyst design and insights into underlying processes have not significantly resulted in urgently needed improvements in water electrolyser performance or higher deployment rates. In light of recent developments in water electrolyser devices

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Renewable Hydrogen and Electricity Dispatch with Multiple Ni–Fe Electrode Storage

Abstract: Materials for Energy Conversion and Storage (MECS),

Cited by 17 publications

References 16 publications

Neutron Diffraction Study of a Sintered Iron Electrode In Operando

Neutron Diffraction Study of a Sintered Iron Electrode In Operando

Characterisation of a Nickel-iron Battolyser, an Integrated Battery and Electrolyser

Water electrolysers with closed and open electrochemical systems

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