Ni-induced interfacial engineering enables recycled aluminum hydride for high-efficiency electrochemical hydrogen storage

Abstract Aluminum-based hydrides are attractive hydrogen carriers because of high gravimetric hydrogen capacity and relatively moderate working temperature. However, poor reversibility significantly increases the difficulty of application of aluminum hydride materials. Electrochemical hydrogen storage represents an attractive alternative for hydride synthesis and recycling which would be integrated with green electricity. In this work, a Ni-induced interfacial activation strategy has been explored by coupling Al derived from spent AlH3 with carbonyl Ni to construct an Al*/Ni composite anode for electrochemical aluminum-hydride synthesis in a LiAlH4/THF system. The optimized Al*/Ni=7:3 anode delivers a high current density of 0.123 A cm−2, which is 2.7 times that of pristine Al*, and retains 80% of its initial current after 3 h of electrolysis, compared with 31% for the Al* anode. The AlH3 formation rate reaches 5.56 mmol h-1 with a Faradaic efficiency of 77.62%, representing a 2.84-fold increase in formation rate compared with the Al* anode. The results of XPS analysis and DFT calculations are consistent with Ni-induced interfacial electronic redistribution and the formation of a polarized Al*/Ni interfacial environment, which lowers the calculated AlH4- activation barrier and stabilizes the AlH3*+H* final state, thereby promoting Al-H conversion and suppressing anode passivation. This work systematically introduces Ni-induced interfacial electronic modulation as an effective strategy for the electrochemical synthesis of aluminum-based hydrides using Al derived from spent AlH3, providing a pathway toward a closed-loop aluminum-based hydride hydrogen-storage system.