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毕业论文网 > 毕业论文 > 材料类 > 材料科学与工程 > 正文

聚苯胺插层的FeOCl纳米片的制备及电化学性能研究毕业论文

 2022-01-31 09:01  

论文总字数:22003字

摘 要

基于氯离子传导的氯离子电池拥有较好的前景,由于其材料的稳定性;可靠的循环能力;原材料资源充足以及其安全性高。FeOCl的放电容量以及循环稳定性较好,但FeOCl电极材料的导电性不高,而且在充放电过程中产生较大的体积变化。通过插层不仅可以使层间距扩大,而且可以改变带系的填充状态和费米能级,大大提升了导电性、离子传输速度和催化活性。

插层苯胺单体在插入FeOCl中时会被聚合,结构嵌入时仍维持层状结构的完整性。苯胺不仅仅是插入FeOCl层间,同时苯胺与少部分FeOCl进行了化学置换,FeOCl中其中有一些铁被氧化还原成 2价,而且还有大多数保持在 3价氧化态。由于聚合物插层,FeOCl的电导率得以改善。聚苯胺和还原FeOCl层都对导电性做出显着贡献。

FeOCl原始样层间距由于苯胺的插层而扩大6埃。FeOCl原始样正极与锂片组成的电池在第一个循环达到最大值142mAh g-1,之后容量快速下降,30个循环之后容量保持率仅为74.8%。苯胺插层一天的FeOCl样品制成的电池最优,无论是充放电的容量(首次放电容量为102mAh g-1,最大容量约120mAh g-1),还是循坏稳定性(30个循环后容量保持率为92.56%),同时表明其在充放电过程中各进行了两步反应。因为插层一天的样品,可能Fe3 只氧化聚合了层间的苯胺。

插层两天的和四天的30个循环后容量保持率均高于FeOCl原始样,所以插层确实改善了FeOCl的循环稳定性。但插层两天的和四天的容量比原始样和插层一天的要低,因为可能在苯胺插层FeOCl的过程中,过多的三价铁被还原成二价铁,由于铁氧键结合力强,所以铁氯键断裂,导致了氯含量的下降,导致容量降低。而插层七天的样品,层结构完全崩塌,FeOCl转化成了无定型的铁氧化合物。

所以随着插层时间的增长,氯含量降低,使得电池容量降低。但插层样品的循环稳定性要优于FeOCl正极。

关键词:氯离子电池(CIB) 苯胺插层FeOCl 电化学性能

Preparation and Chemical Properties of Polyaniline Intercalated

FeOCl Nanosheets

Abstract

Chloride ion-conducting chlorine-based batteries have good prospects due to their material stability, reliable circulatory capacity, adequate raw material resources, and high safety. The discharge capacity and cycle stability of FeOCl are better, but the conductivity of FeOCl electrode material is not high, and it also has a large volume change during charge and discharge. By intercalation, not only can the layer spacing be enlarged, but also the filling state of the belt system and the Fermi energy level can be changed, and the conductivity, ion transport speed, and catalytic activity can be greatly improved.

The intercalated aniline monomer polymerizes when inserted into FeOCl and maintains the integrity of the layered structure when the structure is intercalated. Aniline is not simply intercalated between layers of FeOCl, and aniline is chemically displaced with some of the FeOCl. Only part of the iron in FeOCl is oxidized and reduced to 2 and most of it remains in the 3 oxidation state. Due to the intercalation of the polymer, the electrical conductivity of FeOCl was improved. Both polyaniline and reduced FeOCl layers make a significant contribution to the conductivity.

The spacing of FeOCl original layers is enlarged by 6 angstroms due to intercalation of aniline. The original FeOCl-like positive electrode and lithium battery reached the maximum value of 142mAh g-1 in the first cycle, after which the capacity dropped rapidly, and the capacity retention rate was only 74.8% after 30 cycles. The anoline-intercalated FeOCl samples produced the best cell, regardless of charge/discharge capacity (first discharge capacity of 102 mAh g-1, maximum capacity of about 120 mAh g-1), or cycle stability (30 cycles after The retention rate was 92.56%), and it also showed that each of them performed two-step reaction during charge and discharge. Due to the intercalation of one day's sample, Fe3 may only oxidize and polymerize the interlayer aniline.

The retention of the capacity after 30 cycles of two days and four days of intercalation was higher than that of FeOCl, so the intercalation did improve the cycle stability of FeOCl. However, the two-day and four-day intercalation capacity of the intercalated layer is lower than that of the original sample and the intercalation one day because it may be that during the aniline intercalation of FeOCl, excessive trivalent iron is reduced to divalent iron due to the ferrite-oxygen bond. Strong binding force, so the broken iron chlorine key, resulting in a drop in chlorine content, resulting in reduced capacity. In the intercalated seven-day sample, the layer structure completely collapsed, and FeOCl was converted into amorphous ferrite.

Therefore, as the intercalation time increases, the chlorine content decreases and the battery capacity decreases. However, the cyclic stability of the intercalated sample is better than that of the FeOCl positive electrode.

Key words: chlorine ion battery(CIB);aniline intercalation FeOCl;electrochemical performance

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1引言 1

1.2氯离子电池的原理及其介绍 1

1.3金属氯氧化物正极的概述 4

1.4正极材料FeOCl 4

1.5苯胺插层FeOCl正极材料 7

1.6本文的研究内容和研究意义 8

第二章 实验部分 9

2.1实验仪器设备与主要试剂 9

2.1.1实验仪器设备及规格参数 9

2.1.2实验主要原料及其厂家 9

2.2 苯胺插层的FeOCl正极材料的制备 10

2.2.1 FeOCl的制备反应式 10

2.2.2 苯胺插层的FeOCl复合材料的制备流程图 10

2.2.3 制备步骤 11

2.3 氯离子电池苯胺插层的FeOCl正极的制备及电池组装 12

2.3.1 苯胺插层的FeOCl正极片的制备 12

2.3.2 电解液的制备 12

2.3.3 电池组装 12

第三章 实验分析 14

第四章 结论 20

参考文献 21

第一章 绪论

1.1引言

二次电池在目前很多前沿领域都有着广泛的应用,如新能源领域以及智能手机。同时也为开发新能源,提供了储能保障。锂离子电池因为其比容量高以及其良好的循环稳定性,现在仍然是二次电池市场的宠儿。人们勇于居安思危,因为锂资源也是有限,所以很多研究人员正在研发很多新兴二次电池,如H /OH-,Na ,K ,Mg2 ,Al3 ,Zn2 和F-等为传导的电化学系统[1-8]

氯是元素周期表中氟之后的第二大负电性元素,因此氯离子非常稳定,具有大的稳定的电化学势[9]。而且负极可以使用一些储量丰富的金属元素,不一定需要使用金属锂。更重要的是,氯离子电池的理论能量密度高,有着较好的发展前景。

1.2氯离子电池的原理及其介绍

CIB是一种以Li、Mg等金属元素作为负极材料且基于氯离子转移的新型二次电池。正极为金属氯化物或者金属氯氧化物,负极可以是碱金属、碱土金属或稀土金属[10],氯离子在阴极和阳极之间穿梭,如图1.1。电极之间的氯离子传输可以通过电化学耦合中的电荷补偿来可逆地存储电子[9]

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