论文总字数：41530字

摘 要

镁基储氢电极合金由于理论电化学容量高、资源丰富、价格低廉等优势被认为是最具潜力的镍氢电池用负极材料之一。但是其较差的电化学动力学性能以及在强碱电解液中较差的耐腐蚀性能（循环性能）影响其在实际应用方面的发展。表面修饰以及材料复合被认为是改善储氢合金循环稳定性的有效方法。已有研究工作表明，透氢抗氧聚合物聚甲基丙烯酸甲酯（PMMA）包覆可以大幅改善纳米镁基储氢合金的抗氧化性能，同时不影响氢在体系中的迁移，进而改善其气态储氢性能。但是，PMMA修饰镁基储氢合金在电化学储氢方面的研究尚未见报道，本课题首次采用PMMA对电极片进行表面修饰，阻止碱液对活性物质的腐蚀，最终达到提高电极片在碱液中的循环稳定性的目标。同时，在聚合物中加入聚乙烯吡络烷酮（PVP）修饰的多壁碳纳米管(MWCNTs)，从而提高PMMA修饰膜的导电性以及电化学催化活性。本课题重点研究了PMMA/MWCNTs复合膜修饰Mg₃MnMNi₂储氢合金电极片的铸膜工艺，以及复合膜修饰后电极片体系的电化学储氢性能。

结果表明：经过PVP修饰后，MWCNTs在PMMA中的分散稳定性明显提高。PMMA/MWCNTs复合膜能够完整均一的包覆电极片表面且多次循环后复合膜表面未出现明显的缺陷。通过复合膜包覆，电极片经过三次活化后可以达到最大放电容量（180 mAh/g），其循环稳定性有一定程度的提高，20次循环后电极的容量保有率从30%提高到50%。包覆后的电极片抗腐蚀能力大大增强，动力学性能却降低。分析表明，经过PMMA/MWCNTs复合膜修饰后合金电极表面的电荷转移速率降低，表面阻抗增加，但氢的扩散能力却大幅提高。

关键词：镁基储氢材料 电化学性能 表面修饰 循环稳定性

ABSTRACT

Mg-based hydrogen storage electrode alloy has been considered as one of the most promising candidates as negative electrode materials for nickel-metal hydride battery in view of its high theoretical specific capacity, rich resources, low price, etc. However, its poor electrochemical kinetic properties and poor corrosion resistance (cycling properties) in alkali electrolyte block its practical application. Surface modification and materials compositing are considered as effective methods to improve the cycling properties of hydrogen storage alloy. Previous studies have shown that the gas-selective polymer PMMA coating could improve the gaseous hydrogen storage properties of nano-Mg-based hydrogen storage alloy by enhancing the anti-oxidation ability without blocking the diffusion of hydrogen. However, the PMMA modified Mg-based hydrogen storage alloy has not been reported in the electrochemical hydrogen storage aspect. We firstly used the PMMA to modify the electrode surface, eventually improving the cycling property of Mg-based hydrogen storage alloy electrode. Meanwhile, in order to improve the conductivity and electrochemical catalytic activity of the composite film, we added PVP modified MWCNTs into the PMMA. This project emphasizes the casting process of the polymer coating on the Mg₃MnMNi₂ electrode surface and the electrochemical properties of the electrode after modification.

The results show that the dispersion stability of MWCNTs in PMMA was improved significantly after PVP modification. The PMMA/MWCNTs composite film can be coated on the electrode surface completely. After several charge/discharge cycles, no obvious defects were observed on the surface of the composite film. Through PMMA/MWCNTs film modification, the electrode reached its maximum discharge capacity (180 mAh/g) after 3 activation cycles and the cycle stability of the coated electrode was improved to some extent. After 20 cycles, the capacity retention of the electrode increased from 30% to 50%. The corrosion resistance of the electrode was enhanced greatly after modification, but the kinetic properties were deteriorated. By liner polarization and EIS tests, we figured out that the charge transfer rate on the alloy surface was reduced due to the increase of the surface resistance. However, the hydrogen diffusion capability was increased after PMMA/MWCNTs film modification.

KEYWORDS: Mg-based hydrogen storage materials；Electrochemical properties； Surface modification；Cycling stability

目 录

摘 要 I

ABSTRACT II

第一章 文献综述 1

1.1 引言 1

1.2 电池及Ni/MH电池的发展历史 2

1.3 Ni/MH电池的工作原理 3

1.4 储氢电极合金及其分类 6

1.5 镁基储氢电极研究进展 7

1.5.1 纳米化 8

1.5.2 非晶化 8

1.5.3 薄膜化 9

1.5.4 非化学计量比 10

1.5.5 多元合金化或元素替代 10

1.5.6 表面修饰 12

1.6 氢化燃烧研究合成研究概况 13

1.7 问题的提出和本文的研究内容 15

第二章 实验内容与方法 16

2.1 实验原料 16

2.2 样品的制备 16

2.2.1 样品的原料 16

2.2.2 氢化燃烧合成制备镁基储氢材料 17

2.2.3 PVP-MWCNTs 复合溶液的制备 17

2.2.4聚合物包覆电极片的工艺步骤 17

2.3 样品的电化学性能测试 18

2.3.1 电化学测试装置和方法 18

2.3.2 电化学测试项目及方法 18

2.4 仪器分析 20

2.4.1 光学显微分析 20

2.4.2 SEM分析 20

2.4.3 FT-IR分析 20

第三章 聚合物修饰镁基储氢合金电极及其电化学性能研究 22

3.1 PVP修饰MWCNTs的分散稳定性测试与组成表征 22

3.2聚合物包覆镁基储氢材料的结构表征 26

3.3 PMMA/MWCNTs复合膜包覆对电极片循环性能的影响 28

3.4 聚合物修饰电极片的电化学性能测试 30

第四章 结论与展望 35

4.1 结论 35

4.2  展望 35

参考文献 37

致 谢 44

附 录 45

第一章 文献综述

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