论文总字数：39868字

摘 要

氢能因其产能高效且无污染性已成为全球研究热点。镁基储氢合金性能十分优异，在金属储氢材料中占有重要地位，但因其缓慢的吸放氢动力学、不良热力学性能及较差的空气稳定性给大规模工业应用带来了难题，其中空气稳定性是镁基储氢材料实际应用中要解决的关键问题之一。运用氢化燃烧合成法（Hydriding Combustion Synthesis, HCS）合成储氢合金具有高效节能且产物活性高等优点，同时，结合机械球磨（Mechanical Milling, MM）进行催化剂掺杂可进一步改善储氢合金的吸放氢性能。在本实验中，我们通过在氢化燃烧法合成的Mg-Al合金中，采用机械球磨掺入微米/纳米Ni颗粒，比较并研究了添加微米Ni或纳米Ni的Mg-Al合金氩气保护和空气暴露的综合脱氢性能，归纳催化剂的Ni粒子尺寸与改性效果的规律，最终得出Ni改性Mg-Al合金储氢性能的机理。结果表明，添加了纳米Ni的Mg-Al合金在暴露于空气后仍保持低温脱氢性能，而添加了微米Ni的Mg-Al合金脱氢性能严重下降。在暴露于空气中5天后，我们发现Mg₉₀Al₁₀-nanoNi的脱氢性能仅出现了轻微的衰退，在2800 s内即可释放5.0 wt.%的氢，该脱氢动力学仍然优于未暴露于空气的Mg₉₀Al₁₀-microNi。此外，这种优异的低温脱氢性能可以保持十天左右。X射线衍射分析（XRD）表明，暴露空气中的掺杂纳米Ni的Mg-Al合金脱氢过程中的化学反应与未暴露于空气中的化学反应仍一致，Ni与Mg₁₇Al₁₂反应形成Al₃Ni₂，而掺杂微米Ni样品中的Ni则倾向于与Mg反应形成Mg₂Ni。扫描电子显微镜（SEM）和X射线光电子能谱（XPS）分析表明，纳米Ni均匀分布在Mg-Al合金内部而不是暴露在表面上，这也就是纳米Ni对Mg-Al合金的脱氢诱导作用具有空气稳定性的原因所在。纳米Ni的诱导效应极大地促进了Al对Mg储氢性能的调节，改善了Mg-Al储氢合金的脱氢动力学，且具有空气稳定性。研究镁基储氢合金的空气稳定性对于推进氢能的工业化至关重要。

关键词: 镁铝储氢合金 低温脱氢 空气稳定性 纳米Ni

Abstract

Hydrogen energy has become a global research hotspot because of its high productivity and non-pollution. Magnesium-based hydrogen storage alloys have excellent properties and play an important role in metal hydrogen storage materials. However, its slow hydrogen absorption and desorption kinetics, poor thermodynamic performance and poor air stability has brought difficulties to large-scale industrial applications, among which air stability is one of the key problems. Hydriding Combustion Synthesis (HCS) has the advantages of high efficiency, energy saving and high product activity. At the same time, the hydrogen absorption and desorption performance of the hydrogen storage alloys can be further improved by doping catalysts via mechanical milling (MM). In this experiment, we compared and studied the dehydrogenation performance of Mg-Al alloy with micro/nano-Ni added by MM, and concluded the objective law and modification effect of Ni particle size, and finally get the mechanism of the catalytic effect of Ni. The results show that Mg-Al alloy with nano-Ni added still maintains the low-temperature dehydrogenation performance after being exposed to air, while that of the Mg-Al alloy added with micro-Ni seriously deteriorates. After 5 days of air exposure, we found that Mg₉₀Al₁₀-nanoNi showed a moderate degree of degradation, and 5.0 wt.% of hydrogen can be released within 2800 seconds, whose dehydrogenation kinetics are still better than Mg₉₀Al₁₀-microNi without air exposure. In addition, this excellent low-temperature dehydrogenation performance can maintain for more than ten days. X-ray diffraction (XRD) shows that the chemical reaction of dehydrogenation of Mg-Al alloy with nano-Ni added exposed to air is similar to that of not exposed one. Nano-Ni reacts with Mg₁₇Al₁₂ to form Al₃Ni₂ while micro-Ni tends to react with Mg to form Mg₂Ni. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis show that nano-Ni is evenly distributed in the Mg-Al alloy rather than exposed on the surface, which is the reason why nano-Ni has air stable induction effect. The induction effect of nano-Ni greatly promotes the adjustment of Al to Mg hydrogen storage performance and improves the dehydrogenation kinetics of Mg-Al hydrogen storage alloy, which also has air stability. It is very important to study the air stability of Mg-based hydrogen storage alloy for promoting the industrialization of hydrogen energy.

Keywords: Magnesium-aluminum hydrogen storage alloy; low temperature dehydrogenation; air stability; nano-Ni

目 录

摘 要 I

Abstract II

第一章 文献综述 1

1.1 引言 1

1.2 储氢材料概述 2

1.2.1 储氢合金基本工作原理 2

1.2.2 储氢合金的吸放氢动力学 3

1.3 镁基储氢材料 4

1.3.1 镁基储氢材料概况 4

1.3.2 Mg基储氢材料存在的问题 5

1.3.3 镁基储氢合金的性能改善方法 5

1.3.4 催化剂Ni改性镁基储氢合金 7

1.4 镁铝储氢合金研究现状 8

1.5 金属储氢材料的空气稳定性问题 10

第二章 实验及方法概述 12

2.1 氢化燃烧合成法制备Mg-Al储氢合金 12

2.1.1 氢化燃烧合成法（HCS法）概述 12

2.1.2 氢化燃烧合成法优势

2.2 机械球磨处理Mg-Al储氢合金 13

2.3 部分实验原理及方法 14

2.3.1 XRD分析 14

2.3.2 MDI Jade软件分析 14

2.3.3 SEM分析 14

2.3.4 PCT仪简介 15

2.3.5 差示扫描量热法 15

2.4 实验流程 16

第三章 实验数据分析 17

3.1 Mg-Al储氢合金暴露空气前后性能的改变 17

3.2 实验组准原位XRD分析 19

3.3 暴露空气后Mg-Al合金的脱氢动力学 21

3.4 样品微观结构分析 24

第四章 实验总结与展望 25

4.1 实验结论 25

4.2 本课题的方向与展望 25

参考文献 27

致 谢 35

第一章 文献综述

1.1 引言

随着社会的快速进步，人类对地球资源的消耗需求也越来越大，传统能源例如煤矿、石油等资源日益枯竭，且存在环境污染严重等问题。大多数传统能源也是不可再生能源，也有干涸殆尽的一日。作为国家生产产能发展的重要支持，能源获取的重要性日益突出，为了保护地球资源可持续化发展，同时不破坏生态环境，寻求新型可靠的清洁能源也成了人类当务之急。轻污染、热转化效率高、易获取等性质也成为了当今使用能源的参考前提^[1-3]。

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