Improved Dehydrogenation Properties of LiAlH₄ by Addition of Nanosized CoTiO₃

Abstract

Despite the application of lithium aluminium hydride (LiAlH4) being hindered by its sluggish desorption kinetics and unfavourable reversibility, LiAlH4 has received special attention as a promising solid-state hydrogen storage material due to its hydrogen storage capacity (10.5 wt.%). In this work, investigated for the first time was the effect of the nanosized cobalt titanate (CoTiO3) which was synthesised via a solid-state method on the desorption behaviour of LiAlH4. Superior desorption behaviour of LiAlH4 was attained with the presence of a CoTiO3 additive. By means of the addition of 5, 10, 15 and 20 wt.% of CoTiO3, the initial desorption temperature of LiAlH4 for the first stage was reduced to around 115–120 °C and the second desorption stage was reduced to around 144–150 °C, much lower than for undoped LiAlH4. The LiAlH4-CoTiO3 sample also presents outstanding desorption kinetics behaviour, desorbing hydrogen 30–35 times faster than undoped LiAlH4. The LiAlH4-CoTiO3 sample could desorb 3.0–3.5 wt.% H2 in 30 min, while the commercial and milled LiAlH4 desorbs 2. The apparent activation energy of the LiAlH4-CoTiO3 sample based on the Kissinger analysis was decreased to 75.2 and 91.8 kJ/mol for the first and second desorption stage, respectively, lower by 28.0 and 24.9 kJ/mol than undoped LiAlH4. The LiAlH4-CoTiO3 sample presents uniform and smaller particle size distribution compared to undoped LiAlH4, which is irregular in shape with some agglomerations. The experimental results suggest that the CoTiO3 additive promoted notable advancements in the desorption performance of LiAlH4 through the in situ-formed AlTi and amorphous Co or Co-containing active species that were generated during the desorption process.

Keywords

• lithium aluminium hydride
• hydrogen storage
• additives
• cobalt titanate