共查询到20条相似文献,搜索用时 62 毫秒
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用化学镀法和酸性镀法在LaNi4.75Al0.25材料颗粒表面镀覆铜膜,然后压制成块。处理后材料的放氢速度、导热性能、抗粉化效果有显著提高,其中酸性镀得到的颗粒与化学镀得以的颗粒在元素分布、成分、吸氢量、抗粉化效果等上有较大差别,因此压块的放氢动力学和抗粉化效果也不同。 相似文献
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采用多元合金化及A侧稀土元素Dy取代M1的方法,制备出了多元低钴贮氢合金M1(1-x)DyxNi3.90 Co0.3 M0.4 Cu0.15 Fe0.1 Sno.1 Ti0.05(x=0.00、0.05、0.10、0.15),研究了加Dy对合金的微观结构、组织以及电化学性能的影响。XRD及EDS分析表明,Dy能很好融入主相晶格中,未单独形成第二相。电化学测试表明,适量Dy的加入能够提高低钴舍金的放电容量,以及合金的充放电循环稳定性。 相似文献
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本文研究探讨Mm合金化对难活化的AB2型Zr-Mn-Ni系贮氢合金的晶体结构,电化学容量及贮氢电极活化等特性的影响作用。Mm合金化加入可从根本上改善Zr系贮氢合金电极的活化性能。这与Mm合金化对贮氢电极合颗粒表面化学改性作用以及合金颗粒体内微结构改变等因素有关,XRD分析表明Mm合金化后同氢后金晶体结构仍为C15相,且其中的C14型Laves相含量明显增加,同时,也发现Mm合金化恶化了贮氢合金电化 相似文献
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为了改善La-Mg-Ni基贮氢合金的循环稳定性和综合电化学性能,研究了电镀镍-钴合金对La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10贮氢合金粉末表面形貌和电极电化学性能的影响.FESEM表明,电镀处理后合金粉末表面沉积了球状的镍-钴合金颗粒.电化学性能测试表明,贮氢合金电极的放电容量、高倍率放电性能和循环稳定性均得到了显著改善.200周循环时合金电极的容量保持率从未处理合金电极的60%提高到镀覆镍-钴合金的80%,在放电电流密度1080mA/g下的高倍率放电性能提高了23%.线性极化曲线和电化学阻抗分析结果显示,包覆镍-钴合金后贮氢合金电极表面的电荷转移速率加快,电催化活性提高. 相似文献
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研究了LaxMm1-x(NiCoMnAl)5合金的放氢PCT曲张和MH电极的电化学性能。随La含量增加,该合金平台压P和平台斜率fs降低,平台斜率随温度的变化率k和氢在合金和氢化物中的活度系数γ增加。氢化物形成焓ΔH随La含量增加而增加,电化学容量随之增加,同时,大电流放电性能提高。 相似文献
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Yanran Wang Xiaowei Chen Hongyu Zhang Guanglin Xia Dalin Sun Xuebin Yu 《Advanced materials (Deerfield Beach, Fla.)》2020,32(31):2002647
Hydrogen storage is a vital technology for developing on-board hydrogen fuel cells. While Mg(BH4)2 is widely regarded as a promising hydrogen storage material owing to its extremely high gravimetric and volumetric capacity, its poor reversibility poses a major bottleneck inhibiting its practical applications. Herein, a facile strategy to effectively improve the reversible hydrogen storage performance of Mg(BH4)2 via building heterostructures uniformly inside MgH2 nanoparticles is reported. The in situ reaction between MgH2 nanoparticles and B2H6 not only forms homogeneous heterostructures with controllable particle size but also simultaneously decreases the particle size of the MgH2 nanoparticles inside, which effectively reduces the kinetic barrier that inhibits the reversible hydrogen storage in both Mg(BH4)2 and MgH2. More importantly, density functional theory coupled with ab initio molecular dynamics calculations clearly demonstrates that MgH2 in this heterostructure can act as a hydrogen pump, which drastically changes the enthalpy for the initial formation of B H bonds by breaking stable B B bonds from endothermic to exothermic and hence thermodynamically improves the reversibility of Mg(BH4)2. It is believed that building heterostructures provides a window of opportunity for discovering high-performance hydrogen storage materials for on-board applications. 相似文献
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Metal Hydride Nanoparticles with Ultrahigh Structural Stability and Hydrogen Storage Activity Derived from Microencapsulated Nanoconfinement 下载免费PDF全文
Jiguang Zhang Yunfeng Zhu Huaijun Lin Yana Liu Yao Zhang Shenyang Li Zhongliang Ma Liquan Li 《Advanced materials (Deerfield Beach, Fla.)》2017,29(24)
Metal hydrides (MHs) have recently been designed for hydrogen sensors, switchable mirrors, rechargeable batteries, and other energy‐storage and conversion‐related applications. The demands of MHs, particular fast hydrogen absorption/desorption kinetics, have brought their sizes to nanoscale. However, the nanostructured MHs generally suffer from surface passivation and low aggregation‐resisting structural stability upon absorption/desorption. This study reports a novel strategy named microencapsulated nanoconfinement to realize local synthesis of nano‐MHs, which possess ultrahigh structural stability and superior desorption kinetics. Monodispersed Mg2NiH4 single crystal nanoparticles (NPs) are in situ encapsulated on the surface of graphene sheets (GS) through facile gas–solid reactions. This well‐defined MgO coating layer with a thickness of ≈3 nm efficiently separates the NPs from each other to prevent aggregation during hydrogen absorption/desorption cycles, leading to excellent thermal and mechanical stability. More interestingly, the MgO layer shows superior gas‐selective permeability to prevent further oxidation of Mg2NiH4 meanwhile accessible for hydrogen absorption/desorption. As a result, an extremely low activation energy (31.2 kJ mol–1) for the dehydrogenation reaction is achieved. This study provides alternative insights into designing nanosized MHs with both excellent hydrogen storage activity and thermal/mechanical stability exempting surface modification by agents. 相似文献
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用于超高压化学热压缩的稀土储氢合金研究 总被引:2,自引:0,他引:2
具有融氢净化和氢压缩于一体等重要特性的金属氢化物化学热压缩器将成为未来加氢站的核心设备.本文简要介绍了金属氢化物化学热压缩器的工作原理及其特点,针对金属氢化物化学热压缩器对储氢合金的要求,研究开发了一种储氢性能优良、适合于作为化学氢压缩机用的稀土系储氢合金(Mm-Ml-Ca)(Ni-Al)5,测定了合金热力学和动力学性能.利用该合金设计制作了一台氢容量大于1000L、氢压大于40.0 MPa的压缩器样机,在20℃时氢压小于3.0 MPa可吸氢饱和,165℃放氢可得氢压大于40.0 MPa的超高压产品氢.原料氢纯度为98%时,产品氢纯度达到99.9999%.并且对压缩器的热效率进行了计算,其热效率达到21.9%. 相似文献
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高容量储氢材料的研究进展 总被引:6,自引:0,他引:6
氢能是一种理想的二次能源.氢能开发和利用需要解决氢的制取、储存和利用3个问题,而氢的规模储运是现阶段氢能应用的瓶颈.氢的储存方法有高压气态储存、低温液态储存和固态储存等3种.固态储氢材料储氢是通过化学反应或物理吸附将氢气储存于固态材料中,其能量密度高且安全性好,被认为是最有发展前景的一种氖气储存方式.由轻元素构成的轻质高容量储氢材料,如硼氢化物、铝氢化物、氨摹氢化物等,理论储氢容量均达到5%(质量分数)以上,这为固态储氢材料与技术的突破带来了希望.新型储氢材料未来研究的重点将集中于高储氢容量、近室温操作、可控吸/放氢、长寿命的轻金属基氢化物材料与体系. 相似文献
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在氢气保护下,采用机械合金化制备4MgH_2/TiH_2以及4MgH_2/TiH_2+5%A(质量分数,A=AlCl_3,LaCl_3,CeCl_3)复合材料,并通过PCT、XRD、SEM以及DTA等手段对复合材料进行表征。结果显示,4MgH_2/TiH_2以及4MgH_2/TiH_2+5A(A=AlCl_3,LaCl_3,CeCl_3)复合材料吸氢量均在4.5%(质量分数)左右,且在150s时间内吸氢即可达到饱和。添加CeCl_3后,复合材料的脱氢反应焓从添加前的72.7kJ/mol下降到65.1kJ/mol,而添加AlCl_3和LaCl_3后,复合材料的脱氢反应焓则分别增加到80.6kJ/mol和82.5kJ/mol。这表明CeCl_3能有效提高4MgH_2/TiH_2复合材料的热力学性能,而AlCl_3和LaCl_3的添加则会导致4MgH_2/TiH_2复合材料的热力学性能下降。 相似文献
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非化学计量比贮氢合金及其电极特性 总被引:2,自引:0,他引:2
对贮氢合金M1Ni3.55 xCo0.75Al0.3Mn0.4(0≤x≤0.6)的结构、组织、电化学性能和P-C-T特性进行了研究。结果表明,除了x=0.6的合金外,随着x的增大合金的点阵常数a值减小、c值增大,c/a值和单胞体积也随之增大,而x=0.6时合金体积反而减小。同时随着x的增大,合金中Ni并没有出现明显偏析,而是促进了B侧其它合金元素尤其是Mn和Al的偏析。x的增大,放电容量降低,充放电循环稳定性只略有下降,但活化性能却明显改善,P-C-T曲线平台压升高。 相似文献
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金属氢化物储氢装置研究 总被引:1,自引:0,他引:1
用有限差分法和二维导热模型计算了圆柱形金属氢化物储氢装置内部储氢过程的温度场分布,结果表明空气换热型储氢装置内部的合金反应床存在明显的温度梯度场,吸氢时储氢装置中心部位的温度最高,需要强化其芯部换热条件,以提高储氢装置的储放氢性能.对比研究了铸态以及甩带快淬工艺制备 TiV0.41 Fe0.09Mn1.5合金吸放氢循环寿命,表明甩带快淬工艺可以显著提高储氢合金的吸放氢循环性能.以甩带快淬工艺制备的TiV0.41Fe0.09Mn1.5合金为工质的储氢装置,经过3 600次吸放氢循环后的容量保持率达到94%以上. 相似文献
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Ruyan Wu Xin Zhang Yongfeng Liu Lingchao Zhang Jianjiang Hu Mingxia Gao Hongge Pan 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(32)
Poor reversibility and high desorption temperature restricts the practical use of lithium borohydride (LiBH4) as an advanced hydrogen store. Herein, a LiBH4 composite confined in unique double‐layered carbon nanobowls prepared by a facile melt infiltration process is demonstrated, thanks to powerful capillary effect under 100 bar of H2 pressure. The gradual formation of double‐layered carbon nanobowls is witnessed by transmission electron microscopy (TEM) observation. Benefiting from the nanoconfinement effect and catalytic function of carbon, this composite releases hydrogen from 225 °C and peaks at 353 °C, with a hydrogen release amount up to 10.9 wt%. The peak temperature of dehydriding is lowered by 112 °C compared with bulk LiBH4. More importantly, the composite readily desorbs and absorbs ≈8.5 wt% of H2 at 300 °C and 100 bar H2, showing a significant reversibility of hydrogen storage. Such a high reversible capacity has not ever been observed under the identical conditions. The usable volumetric energy density reaches as high as 82.4 g L?1 with considerable dehydriding kinetics. The findings provide insights in the design and development of nanosized complex hydrides for on‐board applications. 相似文献