论文总字数：15455字

摘 要

固态储氢材料中，镁基合金因储氢密度高、价格低和资源丰富而备受关注，成为未来储能材料首选。然而，镁基合金需要在较高温度（约300 ℃，1巴压力H₂氢气）环境才能有效吸放氢，且动力学差,导致远离实际应用。上世纪末，纳米技术高速发展，特别是纳米材料学诞生，方可能克服镁基储氢合金缺点。理论分析表明，如果镁基合金颗粒尺寸减小至数十乃至数纳米，放氢焓显著降低，导致氢化物失稳和脱氢温度降低。因此，探索、创新纳米尺度镁基储氢材料的制备工艺技术是使镁基储氢材料具备商业可用性的必要措施。

本文综述了镁基储氢材料纳米结晶物理与化学方法的最新进展和作者单位的研究工作，在此基础上，借鉴纳米材料“空间限域（space-confinement)”设计概念，采用最新开发的制备方法——氢化化学气相沉积（Hydriding Chemical Vapor Deposition, HCVD），合成纳米尺寸镁基氢化物。

HCVD是一种典型的气-固晶体生长过程——在高压氢气气氛下，适当控制反应压力与合成时间等工艺参数，借助Mg的蒸发、迁移和沉积，再经降温、氢化，得到具有纳米结构的镁基氢化物。

本文对采用优化工艺参数的HCVD合成产物，进行了微观结构观测和吸/放氢与储氢性能测试。并且，通过与氢化燃烧合成（Hydriding Combustion Synthesis，HCS）工艺产物的脱氢性能和电化学放电特性对比，阐释了HCVD工艺的改善机理。采用HCVD工艺得到的Mg₂NiH₄具有颗粒细小（平均粒径lt;100 nm）、弥散性好、纯度高等优点。

关键词：镁基合金氢化物 氢化化学气相沉积 储氢性能 微观结构

Preparation of Mg-based hydrogen storage materials research and hydrogenated chemical vapor deposition equipment

ABSTRACT

In the solid-state hydrogen storage area, Mg-based alloys have been extensively studied because of their large hydrogen storage density, low price and resource richness and become primary candidate as future energy storage medium. However, a rather high temperature (around 300℃ at 1 bar H₂ pressure) is needed for Mg-based alloys to absorb/desorb hydrogen efficiently and the kinetics are poor, which cause them to be far from practical application. The highly-speed development of nanotechnology, especially the subsequent emerging of nanometer materials science in the end of last century makes it possible to overcome these drawbacks. Theoretical calculations suggest that the hydrogen desorption enthalpy would be largely decreased, leading to the destabilization of the hydrides and the fall of the temperature of hydrogen desorption if the particle size is reduced to dozens of and even a few nanometers. Thus, exploring innovative preparation techniques for nanoscale Mg-based hydrogen storage materials is regarded as one of the essential measures to achieve their availability in commerce.

Based on the review of the latest progress covering both physical and chemical means of nanocrystallizing for Mg-based hydrogen storage materials and our previous work, considering the nanometric materials design concept of space-confinement , the newly developed preparation method, Hydriding chemical vapor deposition (HCVD), have been chosento synthesize nanosized Mg-based hydrides.

HCVD is a typical vapor-solid crystal growth process of the evaporation-condensation of Mg under a high-pressure H₂ atmosphere. Via the vapor-transport and deposition of Mg, subsequent with the cooling and hydrogenation process, and by adjusting the synthesis conditions such as the reaction pressure and holding time, the Mg-based hydrides with a nanostructure may be obtained.

The microstructure characterization and performance measurements of the

HCVDed product with the optimized synthesis parameters was carried out. The improved mechanisms were proposed by comparing with the HCSed product as regard to the dehydrogenation performance and the electrochemical discharging property. HCVDed Mg₂NiH₄ have some advantages: reduced grind size (an average particle size below 100 nm), uniform distribution and relatively high purity.

Key Words: Mg-based alloy hydrides; Hydriding chemical vapor deposition; Hydrogen storage properties; Microstructures

目 录

摘要 …………………………………………………………….…….I

ABSTRACT II

第一章 文献综述 1

1.1引言——储氢载体与储氢材料 1

1.2 镁基储氢材料研究历史概况 4

1.3镁基储氢材料研究主要动向 4

第二章 氢化化学气相沉积高压反应设备研制 7

2.1 反应设备组成 7

2.2 高压反应器的设计 8

2.3 压力与真空系统 11

2.3.1 管路排布 11

2.3.2 管路选材 11

第三章 镁基储氢材料制备及其结构测试 13

3.1 氢化化学气相沉积技术简介 13

3.2 实验材料准备 13

3.3 氢化化学气相沉积制备镁基储氢材料结构测试 15

第四章 结论与展望 18

4.1 结论 18

4.2 展望 18

参考文献 20

致谢 ……………………………………………………………………22

2. 文献综述

1.1引言^[[1]]——储氢载体与储氢材料

储氢载体是氢能源的关键^[[2]]。图1 显示了在氢能源利用中储氢载体的关键地位。

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