Dehydrogenation behavior of ball-milled ammonia borane and lithium hydride mixtures

Density functional theory calculations reveal that the reaction between ammonia borane and lithium hydride is thermodynamically favorable above −46 °C. This reaction takes place during ball milling at 20 °C, but can be suppressed when milling is conducted at liquid nitrogen temperature. Cryomilling for 60 min reduces the reaction temperature from ∼70 °C for unmilled powder to below room temperature, indicating that cryomilling can adjust the onset temperature for releasing hydrogen from solid materials that are thermodynamically unstable but with kinetic barriers.