Taking on Challenges to Apply Celmet™ Porous Metal

A Japanese automaker became the first in the world to develop an HEV. Both a gasoline engine and an electric motor were installed to drive the vehicle, which was designed to use electricity as much as possible to improve fuel efficiency and reduce CO₂ emissions. Celmet^TM was used as the material for the Ni-MH battery installed in the HEV. The material contributed to the spread of environmentally friendly HEVs and the reduction of CO₂ emissions. Ni-MH batteries are characterized by long service life when they are used in HEVs subject to many chargedischarge cycles. They are also resistant to low temperatures and ensure high levels of safety. The Sumitomo Electric Group has been working to develop hydrogen-based applications by harnessing technologies and production capabilities refined in the development of Ni-MH batteries.

There are two ways to generate electricity using hydrogen. One is to use the thermal energy generated during the combustion of hydrogen, and the other is to directly convert hydrogen and oxygen into electrical energy. The latter is the process used in fuel cells, which have attracted public attention due to their high energy conversion efficiency. Home fuel cells are already widely used, and commercial and industrial fuel cells have also started to spread. High expectations are placed on further applications since fuel cells are clean with their only reaction product being water. Notably, solid oxide fuel cells (SOFCs), which operate at high temperatures over 700°C, offer an advantage of eliminating the need for expensive rare materials, including platinum catalysts. Koma Numata works on R&D to apply Celmet^TM to current collectors.

Meanwhile, Okuno is responsible for the application of Celmet^TM to hydrogen production systems. In these systems, water is electrolyzed to produce hydrogen. R&D is under way to apply porous metals to electrodes for water electrolysis.

“Application of Celmet^TM-based electrodes with a high specific surface area will further increase the efficiency of water electrolysis. The bottleneck in water electrolysis is high power consumption. Application of Celmet^TM is expected to reduce power consumption for hydrogen production. We hope to lower the water electrolysis voltage by developing nickel surface modification technology,” said Okuno.

As Okuno pointed out, it is an important engineering challenge to increase the efficiency of water electrolysis. High power consumption also affects the running cost and poses a stumbling block in realizing, expanding, and spreading a hydrogen society. In this context, cost reduction in hydrogen production using Celmet^TM has attracted much public attention. In Japan, a demonstration project using hydrogen production systems has just begun. The market is expected to start growing rapidly between 2025 and 2030, with market size expanding by factors of ten in the following 20 years. New applications of Celmet^TM will emerge in the not-sodistant future.