论文总字数：24245字

摘 要

镁基储氢合金因为具有资源丰富，污染小，理论储氢量高等特点而一直受到人们的关注，但Mg₂Ni二元合金在作为镍氢电池的负极材料时，存在着容易受到碱性电解液腐蚀，循环稳定性不高的特点。因此，在实际应用中要求对其进行改性。通过引入某种具有特定功能的元素，形成新的相结构，实现多元合金化，来改善镁基储氢合金的电化学性能的方法获得了研究人员的一致认可。过渡族金属Ti元素因其良好的抗腐蚀性能，在诸多领域得到了很好的应用，但由于Mg和Ti相互溶解度都很小，传统的高温熔炼的方法难以制得Mg-Ti-Ni三元合金，因此关于它的系统性研究并不多见。我们实验室采取粉末冶金技术工艺，通过探索球磨预处理和烧结的最佳工艺参数，制备出了Mg₃TiNi₂三元合金。然而三元复合体系存在着电化学容量不高的问题，我们推测这可能与Mg-Ti-Ni相含量不高有关。考虑到Mn元素经常被用作形核助剂，且半径与Ti接近，于是我们尝试引入Mn元素，对Ti进行部分取代，形成四元复合体系，以提高Mg-M-Ni (Ti，Mn)相的含量，从而改善其电化学性能。

本文在实验室已经制备了Mg₃TiNi₂合金的基础上，采用相同的工艺参数，制备了Mg-Ti-Mn-Ni四元合金。随后采用XRD对复合体系的结构进行了表征，使用电化学工作站和LAND电池测试系统对负极材料的电化学性能进行了测试。结果表明：Mn含量的增加，促进了Mg-M-Ni (M = Ti，Mn)相的形成，主相的纯度也大大提高。首次放电容量也随着Mn含量的提高而逐步增大，在x = 0.5时，达到最大放电容量215 mAhg^-1。循环稳定性也得到改善，在20次循环之后，容量保有率大于70 %。随着Mn含量的提高，样品的动力学性能也得到了改善。

关键词：Mg₃Ti_1-xMn_xNi₂ 高能球磨 材料结构 电化学性能

ABSTRACT

Mg-based hydrogen storage electrode materials with abundant storage, environmental friendliness and high theoretical hydrogen storage capacity have attracted more and more researchers. However, Mg-based hydrogen storage alloy used as the negative electrode material of the nickel-metal hydride (Ni-MH) battery is easy to be corroded by alkaline electrolyte resulting in lower cycle stability. So, the further modification is very necessary in the practical application. Multi-alloying has been proved to be a popular approach to improve the electrochemical properties of Mg-based hydrogen storage alloy electrode by introducing some elements with specific functions to form a new phase structure. Titanium is considered as an effective anti-corrosion substance and applied in numerous fields. While, due to the low solubility of Ti and Mg, the traditional high-temperature melting method is difficult to produce Mg-Ti-Ni ternary alloy, so the systematic study on it is rare. In our laboratory, powder metallurgy technology was adopted to explore the optimal processing parameters of ball milling pretreatment and sintering, and the Mg₃TiNi₂ ternary alloy was prepared. However, the electrochemical capacity of the ternary composite system is not high, we speculated that this may be related to the low content of Mg-Ti-Ni phase. In order to enhance the content of Mg-M-Ni (M = Ti, Mn) and improve the electrochemical performance, the manganese was introduced into the Mg-Ti-Ni system and the Ti was partially substituted by Mn to form a quaternary alloy, because the manganese is often used as a nucleation agent and its radius close to Ti.

In this work, based on the Mg₃TiN_i2 alloy which had been prepared in our laboratory, Mg-Ti-Mn-Ni quaternary alloy was prepared by the same process parameters. The structure of the alloys was analyzed by XRD, and the electrochemical performance of the anode materials was tested using the electrochemical workstation and LAND cell testing system. The results showed that the strength of Mg₃M₂Ni (M = Ti, Mn) phase diffraction peak was improved with the increase of content of Mn. The first discharge capacity increased with x increased and the maximum discharge capacity was 215 mAh/g when x = 0.5. The Mg₃Ti_1-xMn_xNi₂ (x = 0.2-0.5) system owns an excellent cycle stability property and the capacity retention was greater than 72 % after 20 charge/discharge cycles. The kinetics property was also improved with the increase of x.

KEYWORDS: Mg₃Ti_1-xMn_xNi₂; High energy ball milling; Material structure; Electrochemical property

目录

摘要 I

ABSTRACT II

第一章 文献综述 1

1.1引言 1

1.2镍氢电池 1

1.3制备工艺 2

1.3.1 熔炼法 2

1.3.2 扩散法 3

1.3.3 粉末烧结法 3

1.3.4 机械合金化 4

1.3.5 氢化燃烧合成法 4

1.4镁基储氢合金电化学性能研究进展 4

1.4.1 合金表面处理 5

1.4.2 元素取代 5

1.4.3 复合制备 6

第二章 实验过程和方法 8

2.1 实验原料 8

2.2 样品的制备 8

2.2.1 已有研究工作 8

2.2.2 样品预处理 8

2.2.3 样品烧结 9

2.3 结构表征 9

2.4 电化学性能分析 9

2.4.1工作电极的制作 9

2.4.2 电化学测试装置 9

2.4.3 电化学测试项目 10

第三章 Mg₃Ti_1-xMn_xNi (x = 0.2-0.5)复合体系结构与电化学性能 12

3.1引言 12

3.2 样品制备 12

3.2.1 样品预处理 12

3.2.2 样品烧结 12

3.3 Mg₃Ti_1-xMn_xNi₂（x = 0.2-0.5）复合体系结构表征 13

3.4 Mg₃Ti_1-xMn_xNi₂（x = 0.2-0.5）复合体系的电化学性能 13

3.5 本章小结 20

第四章 结论与展望 22

4.1 结论 22

4.2 建议与展望 22

参考文献 23

致 谢 26

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