Influence of Ti-Rich Secondary Phase on the Hydrogen Storage Performance of V-Based Hydrogen Storage Alloys

Among V (vanadium)-based hydrogen storage alloys, high-V alloys show significant advantages and prospects. However, the small change of V content will have a great impact on the hydrogen storage performances, so it is of great significance to accurately optimize the V content. Herein, the structure and hydrogen storage properties of V75–XTi5+XCr20 (x = 0, 5, 10) alloys were studied, and the underlying micromechanisms were revealed. It was observed that an increase in the Ti/V ratio leads to a rise in the content of the second phase enriched with Ti, yet even a small amount of the Ti-rich phase can significantly enhance activation performance. The hydrogen desorption plateau exhibits a decreasing trend with the increasing presence of the Ti-rich phase. The results indicate that the optimal comprehensive hydrogen storage performance is achieved when the V content is 70 atom %, exhibiting a suitable plateau pressure of 2.84 bar and a high hydrogen storage capacity of 2.40 wt % at 20 °C and 3.00 wt % at 200 °C. Furthermore, after 50 cycles, the capacity retention rate remains as high as 96.4 atom %. This performance establishes a solid foundation for future engineering applications of high-capacity hydrogen storage materials.