Magnesium hydride (MgH₂) as a solid-state hydrogen storage material has obtained intense attention in extensive research because of its high hydrogen-storage capacity, excellent reversibility, and relatively low cost. However, two primary obstacles of slow kinetics during hydrogenation/dehydrogenation process and high thermodynamic stability of Mg-H bond hinders the large-scale application of MgH₂. Therefore, developing high-efficiency catalysts is necessary for hydrogen storage systems. Titanium (Ti) as an active element, shows promising in enhancing hydrogen storage activity and has been reported extensively. Herein, this review summarized the synthesis approaches, testing technology, and hydrogen storage performance of various Ti-based additives in detail. The structure-activity relationship of Ti-based materials was researched by combining experiment and DFT simulations. In particular, the focus is on the investigation of synthesis, characterization and reaction mechanism of various Ti-based additives. The real active sites and different reaction mechanisms during MgH₂ hydrogen storage system are discussed. Finally, a summary and outlook were also presented. This review has the potential to guide the design of high-efficient catalysts and provide embedded guidance for future development and application of Mg-based materials in hydrogen storage system.

The development of high-performance binders is a simple but effective approach to address the rapid capacity decay of high-capacity anodes caused by large volume change upon lithiation/delithiation. Herein, we demonstrate a unique organic/inorganic hybrid binder system that enables an efficient in situ crosslinking of aqueous binders (e.g., sodium alginate (SA) and carboxymethyl cellulose (CMC)) by reacting with an inorganic crosslinker (sodium metaborate hydrate (SMH)) upon vacuum drying. The resultant 3D interconnected networks endow the binders with strong adhesion and outstanding self-healing capability, which effectively improve the electrode integrity by preventing fracturing and exfoliation during cycling and facilitate Li⁺ ion transfer. SiO anodes fabricated from the commercial microsized powders with the SA/0.2SMH binder maintain 1470 mAh g⁻¹ of specific capacity at 100 mA g⁻¹ after 200 cycles, which is 5 times higher than that fabricated with SA binder alone (293 mAh g⁻¹). Nearly, no capacity loss was observed over 500 cycles when limiting discharge capacity at 1500 mAh g⁻¹. The new binders also dramatically improved the performance of Fe₂O₃, Fe₃O₄, NiO, and Si electrodes, indicating the excellent applicability. This finding represents a novel strategy in developing high-performance aqueous binders and improves the prospect of using high-capacity anode materials in Li-ion batteries.

Magnesium hydride (MgH₂) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign; however, it suffers from high dehydrogenation temperature and slow sorption kinetics. Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH₂. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles (NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH₂. With an addition of 5 wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH₂ are lowered to 190 and 242 ℃, respectively. 6.2 wt% H₂ is rapidly released within 30 min at 250 ℃. The amount of H₂ that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4 wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active, reacting with MgH₂ and forming nanosized Mg₂Ni/Mg₂NiH₄. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the (de)hydrogenation kinetics of MgH₂.