Abstract: Ammonia absorption/desorption properties of CaCl₂ and effects of the operation temperature, starting pressure and ball milling treatment were investigated. The post-2h milled sample can be fully ammoniated to form CaCl₂(NH₃)₈ within 15min under 20℃ and 0.55MPa, and the ammonia storage capacity is 55.1wt%, equivalent to be 9.72 wt% of hydrogen. NH₃ can be desorbed from CaCl₂(NH₃)₈ in the temperature range from 20℃ to 300℃ with three stages controlled by temperature and pressure. Six NH₃ molecules can be desorbed at ambient temperature and pressure. Combined with NH₃ decomposition catalyst, CaCl₂ may be one of promising ammonia-based hydrogen storage materials with high capacity. Further investigations indicate that higher operation temperature and starting pressure can improve the ammonia absorption kinetics of CaCl₂, and prolonging ball-milling time can decrease the operation temperature for ammonia desorption of CaCl₂(NH₃)₈ and improve its ammonia desorption kinetics.

Key words: hydrogen storage materials, fuel cell, metal chloride, ammonia absorption/desorption