Work

In-situ TiH/V8C7 from bimetallic TiVC MXene for enhanced hydrogen storage in the 2LiBH4-MgH2

Year: 2025

Type: article

Abstract: • The LMBH + 6 wt% TiVC releases 9.3 wt% hydrogen in 35 min and hydrogenation completes in 30 min. • Hydrogen is more easily diffused through the TiH/LiH/V 8 C 7 /MgB 2 multi-phase interface. • The capacity retention rate is 96 % after the 15 th cycle. • The generation of polyborane and composite aggregation are inhibited after adding TiVC MXene. Catalysis is an effective means to improve the slow kinetics of hydrogen absorption and desorption, as well as the poor cycle life of the 2LiBH 4 +MgH 2 composite system. In this study, The TiVC MXene was obtained by etching TiVAlC and introduced into 2LiH + MgB 2 by ball milling. Products obtained were heated and hydrogenated to prepare the 2LiBH 4 + MgH 2 (LMBH) system, which exhibits distinguished kinetic performance and capacity retention rate. In the LMBH + 6 wt% TiVC, a 9.3 wt% hydrogen is released within 35 min at 400 °C as well as hydrogenation is completed within 30 min at 350 °C, 9 MPa. Moreover, the capacity retention rate was up to 96 % after the 15 th cycle. During the heating and hydrogenation process, the TiH and V 8 C 7 are generated in-situ as active products, and stably exist in the subsequent process to catalyze the hydrogen absorption-desorption reactions of the composite. The presence of TiH/LiH/V 8 C 7 /MgB 2 interface improves the kinetic performance of the system. Reversibility is improved by inhibiting the generation of polyborane and the aggregation during the hydrogen absorption-desorption process. The interface structure-activity relationship is first elucidated that between bimetallic MXene and 2LiBH 4 + MgH 2 composite system during hydrogen absorption-desorption processes, providing a novel viewpoint and optimization path for the modification research of 2LiBH 4 + MgH 2 composites.

Source: Journal of Magnesium and Alloys

DOI: 10.1016/j.jma.2025.09.030