Hydrogen Storage Alloy
Hydrogen Storage Alloy
What is Hydrogen Storage Alloy?
Hydrogen storage alloys are capable of compactly storing hydrogen gas as a metal hydride [solid state] at a compression ratio of 1/1000 or less, and allow hydrogen absorption and desorption at low pressures below 10 atm [1 MPa] (exempt from the High Pressure Gas Safety Act).
Among hydrogen gas storage methods, this is one of the most compact and safest storage approaches available.
In the coming hydrogen society, it is the ideal material for hydrogen utilization in locations requiring safety and security, or where installation space is limited (e.g., city blocks, residential areas, factories, etc.).
Characteristics of Our Hydrogen Storage Alloys
Our company has more than 30 years of business experience with hydrogen storage alloys for nickel-metal hydride battery negative electrodes, and using the accumulated technologies and know-how, we have in recent years been developing, manufacturing, and selling hydrogen storage alloys for hydrogen storage applications.
In terms of alloy systems [alloy types], we focus most strongly on TiFe-based hydrogen storage alloys (hereinafter referred to as TiFe-based alloys).
A key feature of this alloy system is that it contains a large amount of inexpensive iron—40 to 50%—as the main raw material, enabling a significant reduction in raw material costs compared to AB5-type hydrogen storage alloys (hereinafter referred to as AB5-type alloys), which contain 60% or more of expensive Ni and Co.
The hydrogen storage capacity can also be increased by approximately 20% on a weight basis compared to AB5-type alloys (Fig. 1). We believe this makes it ideal for applications that require particularly large amounts of hydrogen in the coming hydrogen society.
In addition, our hydrogen storage alloys are produced using the strip casting method, which yields alloys with excellent uniformity of constituent elements and microstructure. Thanks to this uniformity, the plateau region during hydrogen absorption and desorption is flatter compared to conventional ingot casting materials.
As a specific example, PCT diagrams of strip cast material and ingot cast material with the same composition (TiFe-based alloy) are shown (Fig. 2).
The strip cast material has a greater hydrogen storage capacity and a flatter plateau region compared to the ingot cast material, allowing hydrogen to be utilized until the very end of desorption. This means that the amount of usable hydrogen in the pressure range of 0.1 to 1.0 MPa is significantly increased, enabling us to provide a more practical alloy.
On the other hand, for low-temperature environment applications or high-pressure (room temperature, 1 MPa or higher) applications, AB5-type alloys with higher hydrogen absorption/desorption pressures are also available (Fig. 3).
These alloys are considered ideal for cold climates or applications requiring hydrogen absorption and desorption at high pressures.
![Fig. 3: AB5-type alloy for low-temperature environments (high pressure [room temperature, 1 MPa or higher]) / example](images/P_012_4.png)
We are also available for alloy development consultations and customization based on your specific requirements.