Hydrogen Desorption Properties of LiBH4/xLiAlH4 (x = 0.5, 1, 2) Composites

Abstract

A detailed analysis of the dehydrogenation mechanism of LiBH4/xLiAlH4 (x = 0.5, 1, 2) composites was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD) and scanning electronic microscopy (SEM), along with kinetic investigations using a Sievert-type apparatus. The results show that the dehydrogenation pathway of LiBH4/xLiAlH4 had a four-step character. The experimental dehydrogenation amount did not reach the theoretical expectations, because the products such as AlB2 and LiAl formed a passivation layer on the surface of Al and the dehydrogenation reactions associated with Al could not be sufficiently carried out. Kinetic investigations discovered a nonlinear relationship between the activation energy (Ea) of dehydrogenation reactions associated with Al and the ratio x, indicating that the Ea was determined both by the concentration of Al produced by the decomposition of LiAlH4 and the amount of free surface of it. Therefore, the amount of effective contact surface of Al is the rate-determining factor for the overall dehydrogenation of the LiBH4/xLiAlH4 composites.

Tuning LiBH4 for Hydrogen Storage: Destabilization, Additive, and Nanoconfinement Approaches

“…The reversibility of pristine LiBH 4 demands harsh conditions (>600 • C and >100 bar H 2 ) [1,41], which makes it impossible for its direct use as a hydrogen storage medium for practical applications. Several investigations have been done heading towards thermodynamic destabilization and kinetic improvement of LiBH 4 [29,30,39,46,49,50,53,[58][59][60][61][62][63][64][65][66][67]69,[72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][89][90][91][92][93][94][95][96][97][98][99].…”

“…Table 4): the capacity was proved to be reduced by half in four cycles [74], or even degraded to~15% of the theoretically available H 2 content in 10 cycles [77]. The capacity loss may be due to the combination of several factors [74,[77][78][79][80][81] of reaction products on its surface. Recently, it was shown that the extent of the dehydrogenation reaction greatly depends on the precipitation and growth of reaction products (LiH, AlB 2 , and LiAl) on the Al surface.…”

“…Recently, it was shown that the extent of the dehydrogenation reaction greatly depends on the precipitation and growth of reaction products (LiH, AlB 2 , and LiAl) on the Al surface. Then, a passivation shell formed by these products may be the kinetic barrier to the dehydrogenation of the Al-doped LiBH 4 composite [80,81].…”

Enhancing Hydrogen Storage Properties of MgH2 by Transition Metals and Carbon Materials: A Brief Review

“…Compared with high cost cryogenic liquid storage and dangerous high compression gas tanks, hydrogen stored in solid-state materials shows easy manipulability temperature, low working pressure (Khafidz et al, 2016 ; Rusman and Dahari, 2016 ; Razavi et al, 2019 ). In the past decades, oceans of materials for hydrogen storage have been investigated, including physical adsorbents (carbon and MOF), complex hydrides (LiBH 4 , LiNH 4 , NaAlH 4 ), alloys hydrides (Mg 2 NiH 4 , TiFeH 2 , NaMgH 3 ), and metal hydrides (MgH 2 ) (Shao et al, 2015 ; Zhai et al, 2016 ; Xiao et al, 2017 ; Chen et al, 2019 ; Goto et al, 2019 ; He et al, 2019 , 2020 ; Liu H. et al, 2019 , 2020 ; Song et al, 2019 ; Jansa et al, 2020 ; Yao et al, 2020 ).…”

Dehydrogenation Performances of Different Al Source Composite Systems of 2LiBH4 + M (M = Al, LiAlH4, Li3AlH6)

“…The decomposition enthalpy values of LiBH 4 also reduced to 60.4 kJ/mol. He et al (2019) studied the dehydrogenation performance of LiBH 4 /LiAlH 4 composite, found that 8.7 wt.% of hydrogen was released at 500 • C, and defined a "Li-Al-B-H" compound. Soru et al (2014) focused on the phase structural transformation of the LiAlH 4 + LiBH 4 system, which can produce 6.8 wt.% of hydrogen.…”