金属基负极储能材料构建与研究

发布时间：2018-02-12 08:30

本文关键词： 金属基负极材料成核生长机理储能机理锂离子电池钠离子电池　出处：《常州大学》2017年硕士论文　论文类型：学位论文

【摘要】：金属基材料,由于其理论容量高,工作电压低且平稳,制备工艺简单等特点而成为一类极具潜力的负极材料。但其在循环过程中由于剧烈体积变化而带来的电化学性能不稳定,一直是阻碍其市场化的主要屏障。本论文致力于构建具有稳定电化学性能的二次电池用金属基负极材料,利用基础表征手段探索二次电池用金属基负极材料的成核生长机理,分析反应条件对其成分、结构、形貌变化的影响规律,并结合各类电化学测试手段研究二次电池用金属基负极材料的储能机理,分析其成分、结构、形貌的变化对材料电化学性的影响规律,从而获得制备具有优异电化学性能的金属基负极材料的有效工艺。论文研究的金属基负极材料可主要分为锂离子电池用和钠离子电池用两个部分。1、对于锂离子电池用金属基负极材料,以锰基、铁基和锰铁二元金属材料为主。(1)以过渡金属Mn为基点,研究了材料成分、形貌的变化对其性能的影响。以锰盐和氨水为主要反应物,采用水热法制备了尖晶石相的Mn_3O_4,材料呈现为表面带有附晶的纳米棒状,由于材料具有较大的尺寸维度,且导电率较低,在充放电过程中,材料与电解液的接触润湿、离子/电子的扩散传递都不理想、材料的体积变化较为严重,这导致材料的电化学性能不理想。为解决这一问题,采用了引入还原氧化石墨烯支撑材料的方法,在维护材料结构稳定性和提高导电率的同时,分析了还原氧化石墨烯的加入对复合材料形貌尺寸变化的影响,研究了复合材料的成核生长机理、储能及储能改善机理,获得了具有良好的循环稳定性和倍率性能的Mn_3O_4/还原氧化石墨烯,其首次放电比容量高达897.2 mAh g~(-1),100次循环后,比容量也依然可以保持在450 mAh g~(-1)左右,是没加入还原氧化石墨烯材料之前比容量的4倍。在研究中发现,虽然Mn_3O_4/rGO的循环稳定性得到了提升,但材料的首次库伦效率依旧不理想,这直接导致复合材料的可逆容量还是偏低,因此,对材料的结构进行了重新设计,在复合材料的表面包裹了一层聚吡咯,以减少首次循环固体电解质界面(SEI)膜形成时的容量损耗,首次库伦效率几乎得到了翻倍增长,同时,利用EIS等测试手段分析并掌握了聚吡咯层的作用机理。(2)利用铁基金属材料,研究了材料结构的变化对其性能的影响。Fe_2O_3材料的理论容量要明显高于Fe_3O_4,但实际测试容量却往往较低。同采用水热法制备以上两种铁氧化物,研究两者之间的异同,分析发现结构的差异是导致这种现象的主要原因:立方相的Fe_3O_4较大的晶胞体积及更高的空隙率相较于四方相的Fe_2O_3更适于锂离子的穿插而不会产生较大的体积变化,所以前者在50 mA g~(-1)下循环15周,可以获得921.1 mAh g~(-1)的可逆比容量,而后者的可逆比容量仅有328.3 mAh g~(-1)。(3)除去成分、形貌、结构因素,还利用铁基和锰铁二元金属材料,研究了影响具有类似基础性质材料的性能的因素。采用水热法,制备了同为逆尖晶石相的Fe_3O_4和MnFe_2O_4。研究发现,两者的电化学性能差异很大,分析其储能机理,Fe_3O_4的储能反应是可逆的,而MnFe_2O_4会随着循环的进行分解成具有较小尺度的Fe_3O_4和MnO。储能机理的差异,导致可逆的Fe_3O_4具有更加稳定的循环性能,而随着材料分解带来的结构崩塌使得在55次循环以后,MnFe_2O_4的可逆比容量只有Fe_3O_4的一半。2、对于钠离子电池用金属基负极材料,以锡基金属材料为主。(1)以SnS_2为研究对象,探索了制备具有良好储钠潜力的片状SnS_2材料的方法,并对影响其成长的原料配比、反应时间进行了规律性研究,探索了它的成核生长机理,分析了这些反应条件对其成分、结构、形貌的影响规律。(2)而后对具有合适结构的SnS_2材料进行不同碳材料的复合,研究不同碳材料、不同碳材料掺入量对复合材料的性能影响规律,探索其储能及碳材料改性机理的作用方式,获得具有优异储钠性能的锡基复合负极材料。
[Abstract]:Metal base material, due to its high theoretical capacity, low working voltage and stable characteristics, simple preparation process and become a kind of potential anode materials. But its electrochemical performance in the circulation process because of the dramatic volume changes caused by instability, has been a major barrier to hinder its market. This paper is devoted to to build a stable electrochemical performance of two battery based anode materials for metal based characterization methods explores the two cell based anode materials for metal nucleation and growth mechanism of reaction conditions on the composition, structure, the effect rules of morphology, and the combination of all kinds of electrochemical techniques of the two cell mechanism can use base anode materials for metal storage, analysis of its composition, structure and morphology of the influence of changes on the electrochemical nature, so as to obtain metal based cathode materials prepared with excellent electrochemical performance The effective process of metal based cathode materials. The research can be divided into lithium ion batteries and sodium ion batteries with two parts of.1 for lithium ion battery based anode materials with metal, iron and manganese manganese base, mainly two yuan metal materials. (1) transition metal Mn as the base point, research the material composition, affect the morphology change on its performance. The manganese salt and ammonia as the main reactants, Mn_3O_4 spinel phase were prepared by hydrothermal method, the surface material appears with crystal nano rod, because the material has larger size dimensions, and the conductive rate is low, the charge and discharge in the process of wetting material and electrolyte, ion / electron diffusion transfer is not ideal, the volume change of the material is more serious, which leads to the electrochemical properties of the material are not ideal. In order to solve this problem, the introduction of graphene oxide reduction of support material Method, material and structure in the maintenance of stability and improve the conductivity at the same time, it analyzed the influence on the reduction of graphene oxide composite morphology changes, on the composite nucleation growth mechanism, improve the mechanism of energy storage and energy storage, obtained has good cycle stability and rate performance of Mn_3O_4/ reduction of graphite oxide graphene, the initial discharge capacity of up to 897.2 mAh g~ (-1), after 100 cycles, the capacity ratio remained at 450 mAh g~ (-1), is not to join the reduction of graphene oxide materials before capacity 4 times. In the study found that although the cycle stability of Mn_3O_4/rGO was improved for the first time in Kulun, but the material efficiency is still not ideal, this is a direct result of the reversible capacity of composite materials is low, therefore, the structure of material was redesigned, on the surface of composite package wrapped in a layer of polypyrrole, For the first time in order to reduce the circulation of solid electrolyte interface (SEI) film is formed when the capacity loss for the first time, Kulun efficiency are almost double the growth, at the same time, the analysis of EIS test method and master the mechanism of polypyrrole layer. (2) the use of iron-based metal material, study the effects of the properties of the theoretical capacity of.Fe_2O_3 to the change of Fe_3O_4 was significantly higher than that of material structure, but the actual test capacity is often low. With the hydrothermal synthesis of the above two kinds of iron oxides, the similarities and differences between the two studies, analysis found that the differences in the structure is the main reason of this phenomenon: cubic Fe_3O_4 large cell volume and higher rate of phase space compared to the tetragonal phase Fe_2O_3 is more suitable for the lithium ion with without generating large volume change, so the former in 50 mA g~ (-1) cycle for 15 weeks, you can get 921.1 mAh g~ (-1) reversible specific capacity, The latter than the reversible capacity was only 328.3 mAh g~ (-1). (3) to remove the composition, morphology, structure factors, using iron and ferromanganese two yuan metal materials, performance factors studied with similar basic properties of materials. By hydrothermal method, were prepared with Fe_3O_4 and inverse spinel the MnFe_2O_4. study found that the electrochemical performance difference, analysis of the mechanism of energy storage, Fe_3O_4 storage reaction is reversible, while MnFe_2O_4 will decompose into circulation with difference has smaller scale Fe_3O_4 and MnO. energy storage mechanism, which can be the inverse of the Fe_3O_4 has a more stable cycle performance, and with the material decomposition the collapse of the structure after 55 cycles, the reversible capacity of MnFe_2O_4 is only half the Fe_3O_4.2 for sodium ion batteries with metal tin based anode materials, metal materials. (1) with SnS_2 as the research object, To explore the method of SnS_2 sheet material preparation has good storage potential of sodium, and influence the growth of raw material ratio, reaction time were studied and explored its nucleation and growth mechanism, analyzed the reaction conditions on the composition, structure and morphology of the influence law. (2) and composite different carbon materials on the structure of SnS_2 with suitable materials, the effects of different carbon materials, carbon materials doped with different properties of composite materials, mode of action and explore its mechanism of modification and storage of carbon material, Sn based composite anode material has excellent storage performance of sodium.

【学位授予单位】：常州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB34;TM912

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