Toshiba’s PEM Water Electrolysis Test System Points to High-Pressure Hydrogen Production Using 90% Less Iridium Catalyst

Kawasaki, Japan – Toshiba Corporation, a leading proponent of advancing Power-to-Gas technologies for energy conversion and transportation, has developed a test system for proton exchange membrane (PEM) water electrolysis that produces hydrogen under high-pressure conditions.
Designed to be fully compliant with Japan’s stringent High Pressure Gas Safety Act, the system can evaluate electrolysis at pressures of up to five megapascals (MPa). Toshiba has successfully applied it to evaluation of a membrane electrode assembly (MEA) incorporating its new low-iridium electrode catalyst, which uses 90% less iridium than current assemblies. Under repeated cycles of atmospheric-pressure and high-pressure, with a differential pressure of 3.5 MPa, the assembly demonstrated stable continuous operation for more than 1,500 hours.
The results point toward more efficient storage and transportation of hydrogen, with reduced dependency on a scarce precious metal, and will contribute to making hydrogen a mainstream energy source.
Details of the technology will be presented at the 93rd Annual Meeting of the Electrochemical Society of Japan, which will take place from March 17 to 19 at the Noda Campus of Tokyo University of Science.

As the uptake of renewable energy continues, the use of surplus energy from wind and solar power generation to produce green hydrogen, a clean energy source, is being widely explored. Toshiba is advancing hydrogen production technologies that use renewable electricity for water electrolysis, and its achievements include reducing the amount of iridium used as a catalyst in the electrode by 90%, while scaling up the electrode size^*1.
For practical purposes of storage and transportation, however, hydrogen must be produced at pressures of 3 to 5 MPa. In many systems, this has been done by compressing hydrogen generated at atmospheric pressure. However, this process loses energy while increasing system complexity, and Europe and the United States are moving toward high-pressure water electrolysis, which produces hydrogen at high pressure within the electrolysis cell, as the de facto standard technology.
Japan requires that designs for conducting evaluations under high-pressure conditions meet the requirements of the High Pressure Gas Safety Act, creating a significant barrier to research and development. It has particularly limited environments that seek to verify the durability of low-iridium catalysts under high-pressure conditions.

PEM water electrolysis uses an MEA that integrates the electrolyte membrane and electrodes to electrolyze water and produce hydrogen (Figure 1). In this demonstration, Toshiba incorporated an MEA with a low-iridium anode catalyst formed with its proprietary sputtering method (Figure 2) into its new system for high-pressure PEM water electrolysis. The system closes the hydrogen outlet piping (Figure 3) to realize differential pressure conditions of up to 5 MPa on the cathode side, while the anode side remains at atmospheric pressure. Toshiba conducted over 1,500 hours of continuous operation tests at a current density of 2 A/cm², plus pressure cycle tests that repeatedly alternated between high pressure and atmospheric pressure (Figure 4). No significant increase in cell voltage was observed in any of the tests, confirming stable voltage characteristics. The results verify that Toshiba’s low-iridium electrode catalyst maintains high durability even under high-pressure and in fluctuating pressure environments (Figure 5).
The system was installed at Toshiba’s Corporate Laboratory in Kawasaki, Kanagawa Prefecture (Figure 6). It was designed to be fully compliant with Japan’s High Pressure Gas Safety Act, which ensures safety by specifying facility design and inspection requirements for combinations of pressure and for volumes in high-pressure sections. The system minimizes the internal volume of high-pressure components and evaluates operation at pressures of up to 5 MPa, while meeting regulatory requirements. The compact internal volume also allows rapid pressure cycling within tens of minutes, even with small MEAs, realizing efficient evaluation under conditions that simulate real operating environments.

This achievement is notable for the development of a high-pressure PEM water electrolysis system in Japan, and for demonstrating that an MEA incorporating a reduced iridium electrode catalyst can maintain sufficient durability under pressurized conditions.

Comparison of cell voltage between a continuous operation test under constant pressure and a pressure cycle test involving repeated pressurization and depressurization. Stable voltage characteristics were maintained for over 1,000 hours, confirming stable operation.

Toshiba will leverage its new system for high-pressure PEM water electrolysis to verify its durability under even higher-pressure conditions, and to advance the development of MEA technologies that improve hydrogen production efficiency. Toshiba aims to promote the practical application of high-pressure water electrolysis technologies, to contribute to the widespread adoption of hydrogen derived from renewable energy, and to advance the realization of a hydrogen economy.

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