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The increasing severity of global climate and energy problems has made renewable energy an inevitable choice for achieving a low-carbon society. Hydrogen is regarded as one of the most promising renewable energy due to its excellent characteristics, such as abundant and extensive resources, high calorific value, and non-pollution. How to achieve efficient hydrogen storage is one of the main hot spots of hydrogen energy research. For on-board hydrogen storage systems, which could be used for portable power sources and fuel cell vehicles, how to store hydrogen safely and effectively is one of the most urgent technological bottlenecks to overcome. The solid-state storage based on hydrogen storage materials has the advantages of low hydrogen storage pressure, high energy efficiency, safety and reliability, compared to conventional compressed hydrogen and cryogenic liquid hydrogen storage methods. It may be one of the most promising solutions to solve the above problems. Among the hydrogen storage materials, the lightweight composite hydrides Li–Mg–N–H system holds great promise for vehicular hydrogen storage applications owing to its moderate thermodynamic properties (∆Hdes ~ 44 kJ mol−1 H2 and ∆Sdes ~ 112 J mol−1 H2·K) and relatively high hydrogen capacity (~ 5.6 wt%). However, the Li–Mg–N–H material itself has poor cycling performance and a high energy barrier, resulting in a low dehydrogenation rate and high operating temperature. Apart from this, the multi-field coupling of mass and energy transfer also poses a challenge, hindering its on-board applications. In this paper, we present the modification methods and research status of the Li–Mg–N–H system's hydrogen storage materials. The effects of composition modification, nanocrystallization and catalyst addition on the thermal/kinetic properties of hydrogen storage materials in the Li–Mg–N–H system are expounded. The difficulties and directions for enhancing the hydrogen storage performance of Li–Mg–N–H system are discussed. [ABSTRACT FROM AUTHOR]

Solid-state hydrogen storage device using metal hydride have enormous advantages for fuel cell forklifts. In addition to high volume hydrogen storage density, the solid-state hydrogen storage device can also be used as a counterweight for the forklift. At the same time, the solid-state storage device has low hydrogen storage pressure and safety, and the fuel (H 2) refueling is convenient and low-cost. In this paper, a two-dimensional heat and mass transfer numerical model has been developed to predicting the performance of the metal hydride tank filled with Ti 0.9 Zr 0.1 Cr 0.35 Mn 1.4 V 0.2 Fe 0.05 alloy. The validity of this numerical model was tested by comparison with the experimental data of the metal hydride hydrogen storage tank with a hydrogen capacity of 1 kg, achieving a good agreement between all the data. And a solid-state hydrogen storage device with an effective hydrogen capacity of 1.5 kg is optimally designed for 3.5 T fuel cell forklift. The completion rate of hydrogen refueling in the solid-state hydrogen storage device will reach 97.6 % within 30 min, and continuously discharging over 1.5 kg H 2 under flow rates of 150 SL/min and 250 SL/min. The optimized solid-state hydrogen storage device was integrated in a power module for 3.5 T fuel cell forklift which allows uninterrupted operation for at least 6 h 8 min under rated operation. • Establish and verify a heat and mass transfer model of metal hydride bed. • The solid-state H 2 storage device is optimized using the numerical model. • The H 2 storage device can release over 1.5 kg H 2 and refuel 97.6 % in 30 min • The fuel cell forklift can operate continuously over 6 h. [ABSTRACT FROM AUTHOR]