Lu Wen,Chaojie Li,Houqun Xiao,Huazhou Hu,Chaobin Lai,Luocai Yi,Qingjun Chen
The ZrCo alloy stands out as one of the most promising candidates for hydrogen isotope storage materials in nuclear fusion, owing to its extremely low equilibrium hydrogen pressure (10 −3 Pa, 20 ℃). However, ZrCo experiences severe disproportionation reactions during dehydrogenation/hydrogenation processes, which lead to significant performance degradation. To address this, we have introduced V and Ti into the ZrCo alloy, resulting in the Zr 0.8 V x Ti 0.2-x Co (x = 0–0.15) series. Our research indicates that the addition of V and Ti reduces the lattice parameters, thereby increasing the platform pressure for hydrogen desorption and decreasing the enthalpy and entropy of the desorption reaction. This modification allows for a lower desorption temperature and enhances the alloy's resistance to hydrogen-induced degradation. Remarkably, the hydrogen storage capacity of the Zr 0.8 V x Ti 0.2-x Co(x = 0–0.15) alloys remains stable after 19 h of desorption. Furthermore, the Zr 0.8 V 0.05 Ti 0.15 Co alloy demonstrates exceptional cycling stability, retaining over 99 % of its hydrogen storage capacity after 50 cycles. First-principles calculations have clarified the adsorption energies of hydrogen at different binding sites, revealing the following order of stability: E b(Ti-V) < E b(Zr-Ti) < E b(V-Zr) < E b(Zr-Zr) . The hydrogen absorption and desorption kinetics of the Zr 0.8 V x Ti 0.2-x Co alloys follow the trend: Zr 0.8 V 0.15 Ti 0.05 Co > Zr 0.8 V 0.1 Ti 0.1 Co > Zr 0.8 V 0.05 Ti 0.15 Co > ZrCo, indicating optimized performance with the introduction of V and Ti. This study not only provides a viable solution to the disproportionation issue in ZrCo alloys but also offers valuable insights into the design of high-performance hydrogen isotope storage materials for nuclear fusion applications.
In order to promote the application of ZrCo alloy in storage and delivery system of hydrogen isotope , Zr 1-x Nb x Co (x = 0–0.2) alloys were prepared by induction levitation melting method under argon atmosphere. The effects of Nb substitution for Zr on the microstructure, initial activation behavior, dehydrogenation thermodynamics, disproportionation behavior and cycling stability of Zr 1-x Nb x Co (x = 0–0.2) alloys were systematically investigated. The results show that all alloys contain a ZrCo main phase and a little secondary phase of ZrCo 2 . With the content of Nb increasing, the lattice parameters of ZrCo main phase decrease and the distribution of ZrCo 2 secondary phase is more uniform. It is found that the initial activation period is remarkably reduced from 87.79 h for ZrCo to 8.08 h for Zr 0.8 Nb 0.2 Co. Meanwhile, the equilibrium pressure of hydrogen desorption is enhanced from 0.197 (x = 0) to 0.85 bar (x = 0.2) at 350 °C, which is beneficial to delivery of hydrogen isotope . Further experiments exhibit that the anti-disproportionation performance and cycling stability have been greatly improved after Nb partial substitution, which could be explained by the enlargement of the apparent activation energy from 147.8 kJ/mol (ZrCo) to 182.1 kJ/mol (Zr 0.85 Nb 0.15 Co) for disproportionation reaction.
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