碱性二次电池新型铁负极材料的合成及性能的研究

发布时间：2019-07-10 15:45

【摘要】：在能源枯竭与环境污染问题日益严重的今天,绿色二次电池作为一种新型高效的能源装置获得了与日俱增的关注。铁镍二次电池由于具有循环性能优异、制造成本低、环境友好等优点,被认为是未来较具竞争力的化学电源。当前,铁镍电池依旧存在充电效率低、极易钝化、析气严重、自放电、高倍率性能较差等缺点。因此,在一定程度上制约着其大规模商业化生产。针对上述铁镍电池存在的缺点,本论文主要进行了以下方面的研究:(1)新型FeS@RGO纳米复合材料的合成与研究:通过一个简单的环境友好的直接共沉淀法将FeS纳米粒子固定在还原氧化石墨烯纳米片上,制备出FeS@RGO纳米片复合材料,并将该新型材料首次用作碱性铁镍二次电池负极材料。形貌表征测试表明,FeS纳米粒子均一的、紧密的固定在还原氧化石墨烯纳米片的表面上。电性能测试表明,FeS/RGO电极在没有任何导电添加剂以及具有较高的活性物质负载量(约40 mg cm-2)的条件下,表现出了较好的高倍率充电/放电容量和优异的循环稳定性。在较高的充电/放电倍率5 C、10 C和20 C(6000 mA g-1)下,FeS@RGO电极的放电比容量分别为288 mAh g-1,258 mAh g-1和220 mAh g-1。值得一提的是,FeS@RGO电极在2 C充电/放电倍率下经过300次循环后,容量保持率仍达到87.6%,表现出超好的循环性能。FeS@RGO材料的优异的电化学性能主要来源于其具有较高的比表面积,较高的电导率和强健的薄片支撑结构。由于具有快速的充放电能力,FeS@RGO纳米复合材料非常适合作为高性能的碱性二次电池的负极材料。(2)新型Fe_3O_4@Ni_3S_2复合材料的合成与性能研究:通过简单的三步法成功地制备出Fe_3O_4@Ni_3S_2微球,并将其作为一种新型铁镍电池负极材料。在这种复合材料中,Ni_3S_2纳米粒子紧密地包裹在Fe_3O_4微球的表面上。与纯的Fe_3O_4和Fe_3O_4@NiO微球相比,合成出的Fe_3O_4@Ni_3S_2复合材料表现出更好的高倍率性能。在1200 mA g-1较高的放电倍率下Fe_3O_4@Ni_3S_2电极的放电比容量为481.2 mAh g-1,而纯的Fe_3O_4电极的放电比容量仅为83.7 mAh g-1。此外,相对于纯的Fe_3O_4材料,Fe_3O_4@Ni_3S_2也表现出优异的循环稳定性。在120 mA g-1倍率下,Fe_3O_4@Ni_3S_2电极经过100次循环后,容量保持率高达95.1%,然而纯的Fe_3O_4电极的容量保持率仅为52.5%。可以得知,Ni_3S_2材料的包覆极大地改善了Fe_3O_4@Ni_3S_2电极的电化学性能。研究表明,Ni_3S_2涂层作为一个有益的添加剂,可以明显阻止Fe(OH)2钝化膜的形成,进而增强电极的电子导电性,提高电极反应的可逆性,同时一定程度上可以抑制铁负极析氢反应的发生。由于具有优异的电化学性能,Fe_3O_4@Ni_3S_2复合材料将会是一种很有前途的碱性铁镍二次电池的负极材料。(3)花状NiS的合成及其对铁电极电性能的影响:首先运用L-半胱氨酸辅助法合成花状NiS,并将NiS当作添加剂应用到铁镍二次电池的负极材料中,研究NiS添加剂对铁负极电化学性能的影响。与纯的四氧化三铁电极相比,添加NiS的铁电极表现出较好的高倍率性能和循环稳定性,尤其是添加10%的NiS性能最佳。添加10%的NiS电极在6000 mA g-1较高倍率下的放电容量能达到352.1mAh g-1。并且,在600 mA g-1的倍率下经过100次循环后,其放电容量仍达到406.2 mAh g-1(对应的循环保持率为80.3%)。初步研究表明,NiS可以用作高效的电极添加剂,提高铁镍电池的倍率和循环性能。
文内图片：

图片说明：(a)氧化石墨烯的拉曼光谱图(b)氧化石墨烯的XRD图
[Abstract]:As a new type of high-efficiency energy device, the green secondary battery has gained increasing attention in the day of energy exhaustion and environmental pollution. The iron-nickel secondary battery has the advantages of excellent cycle performance, low manufacturing cost, environmental protection and the like, and is considered to be a more competitive chemical power source in the future. At present, the iron-nickel cell still has the disadvantages of low charging efficiency, easy passivation, serious gassing, self-discharge, poor high-rate performance and the like. Therefore, the large-scale commercial production is restricted to a certain extent. In order to overcome the defects of the above-mentioned iron-nickel cell, the paper mainly studies the following aspects: (1) the synthesis and research of a new FeS@RGO-type nano-composite material: the FeS nano-particles are fixed on the reduction-oxidized graphene nano-sheet by a simple and environment-friendly direct-precipitation method; The FeS@RGO nano-sheet composite material is prepared, and the new material is used for the first time as the negative electrode material of the alkaline iron-nickel secondary battery. The results show that the FeS nano-particles are uniformly and tightly fixed on the surface of the reduction-oxidized graphene nanosheet. The electrical property test showed that the FeS/ RGO electrode exhibited good high rate charge/ discharge capacity and excellent cycle stability under the condition of no conductive additive and high active material loading (about 40 mg cm-2). At higher charge/ discharge rates of 5C, 10C and 20C (6000 mA g-1), the discharge specific capacity of the FeS@RGO electrode was 288 mAh g-1,258 mAh g-1 and 220 mAh g-1, respectively. It is worth mentioning that after 300 cycles of the FeS@RGO electrode at the charge/ discharge rate of 2C, the capacity retention rate still reaches 87.6%, and the excellent electrochemical performance of the super-good cyclic performance .FeS@RGO material mainly comes from the higher specific surface area, Higher conductivity and robust sheet support structures. The FeS@RGO nanocomposite is very suitable as a negative electrode material for a high-performance alkaline secondary battery due to the rapid charge-discharge capability. (2) The synthesis and performance of a new type of Fe_3O_4@Ni_3S_2 composite material: the Fe_3O_4@Ni_3S_2 microspheres were successfully prepared by a simple three-step method and used as a new type of iron-nickel battery cathode material. In this kind of composite material, the Ni _ 3S _ 2 nano-particles are closely packed on the surface of the Fe _ 3O _ 4 micro-sphere. Compared with pure Fe _ 3O _ 4 and Fe_3O_4@NiO microspheres, the synthesized Fe_3O_4@Ni_3S_2 composite has better high-rate performance. The discharge specific capacity of the Fe_3O_4@Ni_3S_2 electrode is 481.2 mAh g-1 at a discharge rate of 1200 mA g-1, and the discharge specific capacity of the pure Fe _ 3O _ 4 electrode is only 83.7 mAh g-1. In addition, the Fe_3O_4@Ni_3S_2 also exhibits excellent cycle stability with respect to the pure Fe _ 3O _ 4 material. The capacity retention rate of Fe _ 3O _ 4@Ni _ 3S _ 2 electrode was 95.1% after 100 cycles at 120 mA g-1. However, the capacity retention rate of pure Fe _ 3O _ 4 electrode was only 52.5%. It is known that the coating of the Ni _ 3S _ 2 material greatly improves the electrochemical performance of the Fe_3O_4@Ni_3S_2 electrode. The results show that the Ni _ 3S _ 2 coating as a beneficial additive can significantly prevent the formation of the Fe (OH)2 passivation film, thereby enhancing the electronic conductivity of the electrode and improving the reversibility of the electrode reaction, and at the same time, the occurrence of the hydrogen evolution reaction of the iron anode can be suppressed to a certain extent. Due to the excellent electrochemical performance, the Fe_3O_4@Ni_3S_2 composite material will be a promising cathode material for the alkaline iron-nickel secondary battery. (3) The synthesis of the flower-like NiS and its effect on the electrical property of the iron electrode: firstly, the flower-like NiS is synthesized by the L-cysteine-assisted method, and the NiS is used as an additive to the cathode material of the iron-nickel secondary battery, and the effect of the NiS additive on the electrochemical performance of the iron negative electrode is studied. Compared with the pure ferroferric oxide electrode, the Fe electrode added with the NiS shows good high-rate performance and cycle stability, in particular, the addition of 10% of the NiS performance is the best. The discharge capacity of 10% NiS electrode at a high rate of 6000 mA g-1 can reach 352.1 mAh g-1. After 100 cycles at 600 mA g-1, the discharge capacity still reached 406.2 mAh g-1 (the corresponding cycle retention rate was 80.3%). The preliminary study shows that NiS can be used as an efficient electrode additive to improve the rate and cycle performance of the iron-nickel cell.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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