Solid Polymer Electrolyte Water Electrolysis Research Articles

Dissolution of hydrogen and the ratio of the dissolved hydrogen content to the produced hydrogen in electrolyzed water using SPE water electrolyzer

Concentration of dissolved hydrogen in electrolyzed water using a solid polymer electrolyte (SPE) water electrolyzer was investigated using a DH-meter. A ratio of the dissolved hydrogen content to an amount of hydrogen concentration calculated from charge passed during electrolysis was estimated. The ratio increased from 10 to 20% with a decrease in current density from 3.0 to 0.3 A dm −2. The effect of the linear velocity of water on the ratio of dissolved hydrogen was studied. The cross-sectional area of the water channel was changed to change the linear velocity of water. The ratio of dissolved hydrogen increased with increasing the velocity. Due to the fast mass transport by high velocity, the small hydrogen bubbles are fast transferred by the diffusion into the bulk water and dissolved. The population density of the small hydrogen bubbles is found to have an effect on the ratio of the dissolving hydrogen.

Simulation and evaluation of a hydrogen storage system using hydrogen storage alloy for a chemical CO 2 fixation and utilization system

Two-dimensional model and simulation programs for designing a hydrogen storage vessel using hydrogen absorbing alloy with tubular heat exchanger were developed with the “Flow-3D” program in which physical properties of the hydrogen storage alloy were incorporated. The calculated results showed good agreement with experimental data obtained from 10 Nm 3 scale hydrogen storage vessel with MmNi 4.64Al 0.36 alloy. It was concluded that this simulation program could be an adequate tool to design a practical scale hydrogen storage system for hydrogen from solid polymer electrolyte water electrolysis and to evaluate its hydrogen storage performance.

Stability of LaNi 5−x Al x alloys ( x=0∼0.5 during hydriding and dehydriding cycling in hydrogen containing O 2 and H 2O

Cycling performance of hydrogen storage LaNi 5 − x alloys under O 2 and H 2O was investigated to develop a hydrogen storage system connected with a solid polymer electrolyte water electrolysis device. The best Al content was found to be between 0.5 and 0.8 through analysis of the initial hydrogen storage capacity decaying curves measured under impure hydrogen gas containing 100 ppm of O 2, introducing a criteria for maximizing the total amount of hydrogen storage for long-term utilization of up to 10 000 cycles.

High Current Density Solid Polymer Electrolyte Water Electrolysis

High Current Density Solid Polymer Electrolyte Water Electrolysis

Design and performance of a solid polymer electrolyte water electrolyzer

The development of medium size solid polymer electrolyte (SPE) water electrolyzers is of great practical interest for on-board production of oxygen in submarines and for energy storage purposes in space applications. While the SPE technology has largely demonstrated its potential on the laboratory scale, very little information is available in the literature on the technological characteristics and electrochemical performances of larger water electrolyzers. In this paper, we present part of the experience that we gained in the development of medium size electrolysis units. A 0.5 kW SPE water electrolyzer was designed and tested. Its performance is discussed with respect to technological design (fluids and current distribution) and operating conditions.

Solid polymer electrolyte water electrolysis: electrocatalysis and long-term stability

In order to enhance the performance and long-term stability of a water electrolysis pilot plant, IrO2/Ti electrodes were hot-pressed on both sides of a Nafion® membrane and tested. By comparison with Pt electrodes, we obtained much lower anodic overvoltages and a better long-term stability of the cell voltage due to a lower cathode sensitivity to poisoning. Purification of water using ion-exchange resins was also useful to prevent a poisoning of the membrane itself. In purified water, assemblies using Pt cathodes and IrO2 anodes were found to be a good compromise between performance and stability.

Characterization of membrane-electrode assemblies for solid polymer electrolyte water electrolysis

The development of medium size SPE® (Solid Polymer Electrolyte) water electrolysers requires satisfactory membrane-electrode assemblies. Pt-Nafion®-Pt, Pt-Ir-Nafion®-Pt and Pt-Ru-Nafion®-Pt composites have been tested for such applications. Anodic overvoltage, cathodic over-voltage and ohmic drop across the SPE® have been measured in the temperature range of 20 to 80° C and in the current density range 0 to 1 A cm−2 Kinetic parameters for the oxygen and hydrogen evolution reactions have been measured and compared to values obtained in aqueous acid solutions. Electrode structure has been investigated, before and after 2 500 h of continuous electrolysis at 1 A cm−2, by scanning electron microscopy, in order to check electrode stability at high current density. The effect of membrane surface etching on the roughness factors of the electrodes has also been investigated. Life tests performed on bare membranes and SPE composites at various operating pressures are presented and discussed. Results on the poisoning effect of nickel ions added to the feed water of the cells are reported.

Gas Evolution Reactions at Conductive Metallic Oxide Electrodes for Solid Polymer Electrolyte Water Electrolysis

Gas Evolution Reactions at Conductive Metallic Oxide Electrodes for Solid Polymer Electrolyte Water Electrolysis

水電解法による水素製造技術の開発動向

The importance of hydrogen as a fuel will steadily increase in future, mainly due to environmental necessities. Water electrolysis is the only proven technology for hydrogen production from nonfossil fuel primary energy sources. R& D on water electrolysis have been done to improve cell performance in efficiency and operating current density, since the energy crisis of 1973. Significant improvements have been made possible and further improvements are anticipated.This paper summarizes the design features of the following three major advanced electrolyzers the advanced alkaline water electrolyzer, the solid polymer electrolyte water electrolyzer and the high temperature water vapor electrolyzer.

Water electrolysis using EME technology: temperature profile inside a nafion membrane during electrolysis

A theoretical model has been developed to predict the temperature profiles across a Nafion membrane during Solid Polymer Electrolyte water electrolysis. Infra-red analysis has been used to check the validity of the model.

Metal and metal oxides based membrane composites for solid polymer electrolyte water electrolysers

The electrocatalytic behaviour of thermally prepared anhydrous RuO 2/Nafion® (prepared by pyrolysis of a RuCl 3 solution on a porous titanium substrate which is then pressed on to the membrane) and platinum/Nafion (prepared by in situ chemical precipitation of platinum particles obtained by treatment of the Pt-exchanged membrane with a NaBH 4 solution) composite electrodes is compared towards the hydrogen evolution reaction in solid polymer electrolyte (SPE) water electrolysis. The metal oxide based composites show moderate electrocatalytic activity compared with the platinum based composites. In contrast, they are not sensitive to poisoning by foreign metal deposition. The RuO 2 based composite electrodes can be alternative cathodic materials for SPE water electrolysers.

In Situ Production of Ozone in Water Using a Membrel Electrolyzer

The application of solid polymer electrolyte or Membrel water electrolysis cells with anodes for anodic generation of ozone in electrolyte‐free water is reported. Maximum yields were obtained at a temperature of 25°–30°C and a current density of 1.0–1.3 Acm−2. The current efficiency was not found to depend on ozone concentration in the feed water. Both, the perfluorinated membrane and the anode do not show any degradation of performance after 2500h of operation. The excellent stability and performance of the cell are correlated with properties of the membrane and its interface with the anode: exclusive transference of electric current by protons; absence of convection in the electrolyte; high oxygen oversaturation in the vicinity of the electrode.

Solid polymer electrolyte water electrolysis

Studies have been made on electrocatalysts and their plating methods to solid polymer electrolyte (SPE). Perfluorosulfonic acid polymer membranes (Dupont manufactured Nafion) were used as SPE. Noble metals and their alloys were directly attached to both sides of the membrane without a binder by special metal plating methods developed by the present authors. The methods, utilizing reactions of a metal salt solution with a reducing agent on the membrane surface, made it possible to increase the adhesive strength of electrocatalysts to the membrane and also to eliminate, almost perfectly, the resistance of electrocatalyst/SPE interface. Pretreatments of the membrane were also investigated in order to improve the adhesive property. It was found that hydrothermal treatment and gas plasma treatment were more effective. The constituents of cell voltage, i.e. anodic and cathodic overvoltages and ohmic drop, were measured for five noble metals and their alloys. The anodic overvoltages were a major constituent of voltage losses and depended distinctly on the kinds of electrocatalysts used. The anodic overvoltage increased in the following order: Ir < Rh < Rh/Pt < Pt/Ru < Pt < Pd. Pure Ru had high initial activity. However, it was corroded during oxygen evolution. The electrodes based on Ir-Ir alloys were the best electrocatalysts for oxygen evolution and had a Tafel slope of 40–60 mV decade −1. The effects of the operating temperature on the cell performance were also studied. The cathode and anode were a thin layer of Pt and similar layer of Ir alloy, respectively. The cell voltage decreased with an increase in temperature. At a current density of 500 mA cm −2 and at 90°C, the cell voltage was 1.56–1.59 V corresponding to a thermal efficiency (based on ΔH) of 93–95%.

Advances in oxygen evolution catalysis in solid polymer electrolyte water electrolysis

Continuous polarization of a stabilized RuO 2 oxygen anode in a solid polymer electrolyte water electrolysis cell at 1072 mA cm −2 resulted in severe anode deterioration within 24–48 hr. In contrast, a new Ru-based mixed oxide catalyst, termed WE-3, exhibited stability in oxygen evolution over a 6700 hr period, with testing beyond that point still in progress. The activation energy for oxygen evolution on WE-3 is comparable to that observed on new RuO 2 anodes.

Solid polymer electrolyte water electrolysis—development status

The development program has centered around achieving lower cost and higher efficiency electrolytic cells. For lower cost the following areas are being investigated: low cost materials for separators and current collectors; elimination of gasket seals; use of lower cost catalyst; reduced catalyst loadings; and lower cost lectrolyte. Areas being investigated for higher efficiency are: operation at higher temperature (up to 150/sup 0/C); improved catalytic electrodes; and optimization of the electrolyte and cell design. (LK)

Conceptual design of large scale water electrolysis plant using solid polymer electrolyte technology

In an energy conscious environment, the key to the applicability of water electrolysis as a means for generation of hydrogen in bulk quantities is the achievement of high efficiencies (i.e. over 90%) at high enough current densities to keep the capital costs within economic bounds. The solid polymer electrolyte (SPE) water electrolysis technology developed by the General Electric Company is now demonstrating these efficiencies at current densities up to 500 A ft −2, and the results of recent laboratory testing show a potential for increasing this to 2000 A ft −2 within the next 10 years. This capability now makes water electrolysis one of the most promising methods for generating hydrogen from nuclear, solar or other non-fossil fuel energy sources. The performance and life test results are shown including laboratory cells on which future performance projections are based. The design and development status of a scaled-up electrolysis cell suitable for large-sized hydrogen generation plants is described. Estimated capital costs and operating costs are projected from which the resultant hydrogen costs are calculated.