Page 62 - Kỷ yếu hội thảo quốc tế: Ứng dụng công nghệ mới trong công trình xanh - lần thứ 9 (ATiGB 2024)

th
HỘI THẢO QUỐC TẾ ATiGB LẦN THỨ CHÍN - The 9 ATiGB 2024 53

material with 59.4% Mn has demonstrated the best
performance and exceptional durability after numerous
hydrogen uptake and release cycles [43].
3.4. LaNi5
LaNi5 alloy, a typical intermetallic compound, has
been extensively studied for its ability to reversibly
absorb and release approximately 1.4% by weight of
hydrogen at ambient conditions of temperature and
pressure. Although its hydrogen retention capability is
not high, LaNi5 is still widely used in metal hydride
batteries and Sabatier reactions (converting CO2 into
methane) [46, 47]. Additionally, in the form of
nanoparticles, LaNi₅ exhibits catalytic potential due to
Figure 3. TiFe phase diagram its large surface area and high activity [48, 49].
as evaluated by Murray [38] However, the traditional production method of
TiFe is typically produced by melting the high-temperature melting is not suitable for creating
constituent elements at high temperatures [40]. This LaNi5 nanoparticles. Conventional grinding processes
binary compound is formed from the melting process only produce large particles (10-20 μm or 20-100 μm)
through the liquid reaction TiFe2 → TiFe at 1317°C. In [50], significantly reducing hydrogen storage capacity.
addition to the melting method, TiFe can also be Moreover, the grinding process negatively affects the
fabricated and processed using Severe Plastic material's ability to repeatedly absorb and release
Deformation (SPD) methods, including high-pressure hydrogen [51, 52].
torsion [41], or by self-combustion [42]. The SPD 3.5. NaAlH4
process creates lattice deformations and increases the Sodium aluminum hydride (NaAlH4), or sodium
surface area, thereby activating the alloy and forming a alanate, is another widely studied hydrogen storage
nanostructure. However, this process also reduces the material. With the ability to operate at low temperatures
density of the material [36]. and pressures, NaAlH4 is considered a promising
3.3. TiMn2 candidate for automotive fuel cell systems [53, 54].
NaAlH4 possesses a robust crystalline structure at
The TiMn2 alloy, belonging to the AB2 intermetallic
compound group with a Laves (C14) crystal structure, ambient temperature, making it easy to manufacture
has a significantly higher hydrogen absorption capacity and handle. Notably, NaAlH4 has a high hydrogen
compared to the AB5 type LaNi5 alloy, reaching 1.8 to storage capacity, low production costs, and abundant
2.0% by weight [43]. The outstanding features of supply [56, 57].
TiMn2 include easy activation, fast hydrogen The release of NaAlH4 occurs through three
absorption and desorption rates, and a wide operating hydrogen desorption stages, with a total hydrogen
pressure range. Therefore, this alloy is currently the capacity of 7.5% by weight [58-61]:
focus of many studies in the field of hydrogen storage. NaAl → N AlH + 2 + 3 at 185-230°C,
2
3
4
6
In the binary Ti-Mn alloy system, TiMn 2 releasing 3,7% by weight of hydrogen.
demonstrates superior hydrogen uptake performance N Al → 3N + + at 260°C, 1.9% of
1
compared to TiMn. Specifically, TiMn1.5 achieves a 3 6 2 2
hydrogen absorption capacity of about 1.8% by weight the hydrogen by weight is released.
at room temperature. However, alloys with less than 36% 3N H → 3N + at 435°C, the remaining
1
Ti content often find it difficult to absorb hydrogen at 2 2
ambient temperatures, while alloys richer in Ti can 1.9% by weight of hydrogen is released.
react with hydrogen without the need for initial However, the primary disadvantage of NaAlH4 is its
activation [44]. sluggish hydrogen release rate and limited reversibility
Liang and co-workers [45] have shown that TiMn 1.5 at temperatures under 150°C. [62].
has the best performance due to its chemical 3.6. LiBH4
composition situated within the titanium-rich domain of LiBH4 is recognized as a promising material for
the Laves phase. Research by Semboshi and colleagues hydrogen storage because of its substantial hydrogen
has shown that increasing the TiMn 2 phase content and content, with 18.5% by weight and 121 kg H 2/m³ by
decreasing the Mn content significantly improves volume. However, the complete utilization of
hydrogen absorption and desorption capabilities. The hydrogen in LiBH4 is hindered because its

ISBN: 978-604-80-9779-0