Scientists from Amrita Vishwa Vidyapeetham University in India, Forschungszentrum Jülich in Germany and the Eindhoven University of Technology in the Netherlands have developed improved alloys based on titanium, vanadium and chromium (TiVCr) that can efficiently store and release hydrogen at room temperature. This discovery brings us closer to the creation of reliable and cost-effective hydrogen storage systems that can, inter alia, be used in transport and storage systems for energy produced by solar and wind power plants.
The problem that the researchers focused on is that most metal hydride materials either store little hydrogen or require high temperatures to release it. The TiVCr alloy is considered one of the most promising: it can absorb up to 4% of hydrogen by weight, but releases it only when heated above 300°C. This makes its use impractical under normal conditions.
To solve this problem, the scientists conducted a series of experiments with the addition of small amounts of nickel (Ni) and niobium (Nb) to the alloy. They obtained three compositions: with 5% nickel, with 10% nickel and with 5% nickel + 5% niobium. These materials were synthesized using the arc melting method; the scientists studied their structure, hydrogen properties and behavior at different temperatures.
The results showed that nickel accelerates the initial absorption of hydrogen, acting as a catalyst on the surface of the alloy. At the same time, the alloy with 10% nickel reached a maximum capacity of 3% hydrogen by weight even at room temperature. In turn, niobium facilitates the movement of hydrogen inside the material and reduces the temperature at which hydrogen begins to be released. Due to this, the alloy with the addition of niobium showed the best release of hydrogen requiring minimal activation energy.
In addition, all the obtained alloys demonstrated structural stability after multiple cycles of charging and discharging with hydrogen. This means that they can potentially be used in real systems where the material must remain usable for a long time without degradation.
The work of the researchers has therefore proved that the rational selection of elements in the composition of high-entropy alloys makes it possible to improve their properties in a targeted manner. In this case, it means taking a step towards the creation of compact, stable and energy-efficient hydrogen storage devices that can operate at normal temperatures and pressures. This opens up prospects for the development of environmentally-friendly transport, off-grid energy systems and a wider use of hydrogen as a universal energy carrier.
