本文選題：儲氫材料 + LiMgBNH　； 參考：《北京有色金屬研究總院》2015年碩士論文

【摘要】：Li-Mg-N-H復(fù)合儲氫材料具有較大的儲氫容量和良好的可逆性,成為最有希望的實(shí)用儲氫材料之一,但緩慢的吸放氫動力學(xué)限制了其廣泛應(yīng)用。添加LiBH4后,材料動力學(xué)性能得到一定改善,但放氫溫度仍然較高,且循環(huán)性能較差。催化和復(fù)合可有效提高LiMgBNH (1.1 MgH2-2LiNH2-0.1 LiBH4)儲氫材料的動力學(xué)和熱力學(xué)性能。本文首先研究了三種不同AB5型合金(LaNi3.8Al0.75Mn0.45、LaNi4Co、LaNi4.5Mn0.5)對LiMgBNH儲氫材料吸放氫動力學(xué)性能的影響。三種合金均可有效改善LiMgBNH材料的放氫動力學(xué),降低放氫溫度和放氫反應(yīng)激活能,其中對動力學(xué)性能改善最顯著的是LaNi4.5Mn0.5合金。AB5型合金并未與LiMgBN H生成新相,合金產(chǎn)生催化作用的原因可能是合金的添加使LiMgBNH中N-H鍵的鍵能減小,有利于材料放氫,彌散分布的合金顆粒使合金的催化作用得以充分發(fā)揮。通過比較不同制備工藝對復(fù)合材料放氫動力學(xué)及循環(huán)性能的影響,發(fā)現(xiàn)高球料比制備的10wt.% LaNi45Mn0.5樣品雖然具有較好的動力學(xué)性能,但因合金及基體材料顆粒較細(xì),在吸放氫循環(huán)過程中容易聚集長大,150℃下循環(huán)性能較差,其平均放氫衰減量約為LiMgBNH樣品的2倍。而低球料比制備的10 wt.% LaNi4.5Mn0.5樣品合金顆粒尺寸增大,循環(huán)性能較LiMgBNH樣品有明顯改善。循環(huán)過程中顆粒的聚集長大增大了擴(kuò)散傳質(zhì)的距離,引起動力學(xué)衰減,從而造成容量衰減。降低球料比后,樣品中顆粒較大的LaN45Mn0.5合金具有一定的分散強(qiáng)化催化作用,即合金在循環(huán)過程中發(fā)生開裂粉化,一方面改善了顆粒的聚集情況,另一方面增大了合金的分散程度,使合金的催化性能發(fā)揮更充分,這可部分抵消因顆粒長大造成的動力學(xué)衰減,從而提高材料循環(huán)穩(wěn)定性。本文研究了溫度對復(fù)合材料吸放氫性能的影響,發(fā)現(xiàn)溫度降低時(shí),由于原子擴(kuò)散減緩,復(fù)合材料動力學(xué)性能衰減明顯。降低循環(huán)溫度至140℃,低球料比制備的10wt.%LaNi4.5Mn0.5樣品循環(huán)性能沒有因顆粒長大減緩而改善。吸放氫不充分仍是其循環(huán)放氫衰減的一個(gè)重要原因。LaNi4.5Mn0.5合金可有效改善復(fù)合材料的顆粒聚集情況,但較小的添加量使其改善作用有限。將復(fù)合材料中LaNi4.5Mn0.5含量提高至30wt.%,材料的動力學(xué)性能提高,顆粒聚集情況明顯改善。但材料顆粒長大明顯,其150℃下循環(huán)性能與LiMgBNH樣品及10wt.% LaNi4.5Mn0.5樣品相比變差。原因是球磨過程中合金對基體材料有研磨作用,使基體材料顆粒變細(xì),循環(huán)過程中更易長大。為進(jìn)一步研究增大添加量后合金對復(fù)合材料循環(huán)性能的影響,將循環(huán)溫度提高至180℃。LiMgBNH樣品循環(huán)性能變差,而30wt.% LaNi4.5Mn0.5樣品循環(huán)性能相對于未添加樣有了明顯的改善。由于循環(huán)溫度升高,循環(huán)過程中顆�？焖匍L大,合金的分散強(qiáng)化催化作用變得明顯,因此添加合金的復(fù)合材料循環(huán)性能明顯改善。為降低合金對基體材料顆粒的研磨作用,采用三維擺動混合方法制備了30 wt.% LaNi4.5Mn0.5樣品,由于合金分散度下降,其動力學(xué)性能較球磨樣下降。因基體材料顆粒大小對復(fù)合材料循環(huán)性能的影響較大,150℃下該混合樣品循環(huán)性能相對于球磨的30wt.%LaNi4.5Mn0.5樣品有了明顯提升。合金的添加也使混合樣品的循環(huán)性能優(yōu)于LiMgBNH樣品。
[Abstract]:Li-Mg-N-H composite hydrogen storage materials have large hydrogen storage capacity and good reversibility, and become one of the most promising practical hydrogen storage materials. However, the slow desorption kinetics limit its wide application. After adding LiBH4, the dynamic properties of materials are improved, but the hydrogen storage temperature is still high, and the cycle performance is poor. Catalysis and complex. The kinetic and thermodynamic properties of LiMgBNH (1.1 MgH2-2LiNH2-0.1 LiBH4) hydrogen storage materials can be effectively improved. In this paper, the effects of three different AB5 alloys (LaNi3.8Al0.75Mn0.45, LaNi4Co, LaNi4.5Mn0.5) on the absorption and desorption kinetics of LiMgBNH hydrogen storage materials are investigated. The hydrogen release kinetics of LiMgBNH materials can be effectively improved by three kinds of alloys. The most significant improvement of the kinetic properties is that the LaNi4.5Mn0.5 alloy.AB5 alloy does not produce a new phase with LiMgBN H. The reason for the catalytic effect of the alloy may be that the alloy addition makes the bond energy of the N-H bond in LiMgBNH decrease, which is favorable for the material to degenerate and the dispersed alloy particles make the alloy. By comparing the effects of different preparation processes on the kinetics of hydrogen release and the performance of the composites, it is found that the high ball material has better kinetic properties than the 10wt.% LaNi45Mn0.5 sample prepared, but it is easy to gather and grow at 150 degrees in the process of hydrogen absorption and desorption because of the fine particles of the alloy and the matrix material. The lower cycle performance is poor, and the average dehydrogenation reduction is about 2 times that of the LiMgBNH sample. The size of the low ball material is larger than that of the 10 wt.% LaNi4.5Mn0.5 sample, and the cycle performance is obviously better than that of the LiMgBNH sample. The aggregation and growth of the particles increases the distance of the diffusion mass transfer and causes the kinetic attenuation, resulting in the capacity of the sample. Attenuation. After reducing the ball ratio, the larger LaN45Mn0.5 alloy in the sample has a certain dispersion strengthening catalysis, that is, the alloy has cracked powder during the cycle process. On the one hand, the aggregation of the particles is improved. On the other hand, the dispersing degree of the alloy is increased and the catalytic performance of the alloy is more fully played, which partly counteracts the due to the grain. The effect of temperature on the performance of hydrogen absorption and desorption is studied. The effect of temperature on the performance of hydrogen absorption and desorption is studied. It is found that when the temperature is reduced, the dynamic properties of the composites are attenuated because of the reduction of atomic diffusion. The circulation of 10wt.%LaNi4.5Mn0.5 samples prepared by low ball material is reduced to 140 degrees C. .LaNi4.5Mn0.5 alloy can effectively improve the particle aggregation of the composite material, but the small amount of addition makes it limited. The content of LaNi4.5Mn0.5 in the composite is increased to 30wt.%, and the dynamic properties of the material are raised. The agglomeration of particles is obviously improved, but the growth of the material particles is obvious, and the cycling performance at 150 C is worse than that of the LiMgBNH samples and the 10wt.% LaNi4.5Mn0.5 samples. The reason is that the alloy has a grinding effect on the matrix material in the ball milling process, making the matrix material finer and more easy to grow in the cycle process. The effect of alloy on the cyclic properties of the composites is that the cycling performance of the samples is worse than that of the samples at 180.LiMgBNH, while the cyclic properties of 30wt.% LaNi4.5Mn0.5 samples are obviously improved compared to the non addition samples. The particles grow rapidly in the cycle process and the dispersion strengthening catalysis of the alloy becomes obvious because of the increase of the cycle temperature. In order to reduce the grinding effect of the alloy to the matrix material, the 30 wt.% LaNi4.5Mn0.5 samples were prepared by the three dimensional swinging mixing method. The kinetic properties of the composites decreased because of the decrease of the dispersion of the alloy. The influence of the particle size of the matrix material on the cyclic properties of the composites was observed. The cyclic performance of the mixed sample is obviously improved at 150 C at 150 C. The addition of the alloy also makes the cycling performance of the mixed sample better than that of the LiMgBNH sample.

【學(xué)位授予單位】：北京有色金屬研究總院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB34

【共引文獻(xiàn)】

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本文編號：1773569