多酸基复合材料的设计合成及其在电化学储能领域中的应用研究

发布时间：2018-01-06 14:37

本文关键词：多酸基复合材料的设计合成及其在电化学储能领域中的应用研究　出处：《东北师范大学》2017年博士论文　论文类型：学位论文

【摘要】：多酸(简称POMs)因其丰富的氧化还原性质而被认为是一类很有潜力的电化学储能材料,素有“电子蓄水库”或“电子海绵”之称。基于多酸的无机-有机复合材料有效地结合了多酸的氧化还原特性和有机基底的导电性与柔韧性,并避免了多酸自身的导电性差、在电解质中部分溶解以及机械柔韧性差等缺陷,从而实现了多酸在电化学储能领域中的应用。本论文从Keggin型混配杂多酸和同多钼酸盐出发,选用的导电基底有石墨烯、聚多巴胺和乙炔黑,设计合成了一系列高多酸含量的复合材料,并研究了复合材料在超级电容器、锂离子电池和钠离子电池领域中的性能。1.通过简单的水热法,一步制备了一系列具有三维多孔结构的多酸与阳离子化石墨烯复合物,即POM-PDDA-RGO新型复合材料。其中选用Keggin型混配杂多酸H_3PMo_(12-x)W_xO_(40)(x=1-6)、H_4PMo_(11)VO_(40)、H_5PMo_(10)V_2O_(40)和H_6PMo_9V_3O_(40)为多酸部分,记为PMoW和PMo V;以聚阳离子电解质,即聚二烯丙基二甲基氯化铵(PDDA)功能化的石墨烯(PDDA-RGO)为导电基底,通过结合混配型多酸独特的氧化还原性质,PDDA紧密的连接性与石墨烯良好的导电性,POM-PDDA-RGO三元复合材料有效地避免了多酸在电解质中的溶解性,并且在酸性电解质(1 mol L~(-1) H_2SO_4溶液)中表现出优越的电化学性能。以PMo W-PDDA-RGO为例,表现出高的比容量,良好的倍率性能(在10 A g~(-1)的高电流密度下比容量为140 F g~(-1)),稳定的循环性能(5 A g~(-1)下循环1700圈后容量保持率为94.6%)以及高的能量密度。复合材料在250 W kg~(-1)的功率密度下,有6.15W h kg~(-1)的能量密度。2.通过水热法一步实现了多酸辅助原位聚合多巴胺,并制备出一系列基于多酸与聚多巴胺的复合材料PMo_(11)V/PDA、PMo_(10)V_2/PDA和PMo_9V_3/PDA。这种多酸辅助的原位聚合法对于合成其它多酸与聚多巴胺的复合物具有一定普适性。聚多巴胺作为一类仿生聚合物材料,具有独特的电子转移性质和粘附性,与具有多步氧化还原性质的Keggin型Mo/V混配杂多酸相结合表现出良好的电化学活性和稳定性,并成功作为无粘结剂添加的高性能锂离子电池负极材料。其中,复合材料作为电极活性材料的含量为80 wt%,表现出良好的电化学性能。电化学测试结果表明PMoV/PDA系列复合材料具有高的放电比容量,优异的倍率性能和长循环稳定性:以PMo_(10)V_2/PDA为例,首圈的放电比容量为1654 mA h g~(-1),相应的库伦效率为66.5%;在高电流密度2000 mA g~(-1)下的放电比容量达到559.6 mA h g~(-1);在100 mA g~(-1)下经历65个循环后放电比容量几乎没有衰减,仍保持在915.3 mA h g~(-1),库伦效率达到99%以上。在高电流密度1000 mA g~(-1)条件下,300圈循环后容量保持率高达93%,库伦效率也达到99%以上。3选用同多钼酸盐Na_6Mo_7O_(24),通过一步球磨的方法,与廉价易得的导电碳乙炔黑(AB)复合,制备了Na_6Mo_7O_(24)/AB纳米复合材料。将Na_6Mo_7O_(24)/AB复合材料作为钠离子电池负极材料,研究了其电化学性能。实验表明,与纯的Na_6Mo_7O_(24)相比,Na_6Mo_7O_(24)/AB复合材料的电化学性能明显提高,说明七钼酸钠在钠离子电池中具有很好的应用前景,同时也拓宽了同多酸在电化学储能领域中的应用。
[Abstract]:Polyoxometalates (POMs) because of its rich redox properties and is considered as a promising electrochemical energy storage material, known as the "electronic reservoir" or "electronic sponge" said. Conductive polyoxometalate inorganic organic composite materials effectively combines the oxidation reduction characteristics and organic acid based on the flexibility of the substrate and, and to avoid the more acid conductive difference defects in electrolyte partial dissolution and poor mechanical flexibility, so as to realize the application of acid in electrochemical energy storage in the field. This paper mixed with molybdenum heteropoly acid and acid salt from the Keggin type of conductive substrates used are graphene polydopamine and acetylene black, a series of high acid content of composite materials were designed and synthesized, and the composite materials in the super capacitor, the performance of.1. lithium ion batteries and sodium ion batteries through a simple hydrothermal method. A series of three-dimensional porous structure of multi acid and cationic graphene composite preparation step, namely POM-PDDA-RGO model of composite materials. The selection of Keggin type mixed heteropoly acid H_3PMo_ (12-x) W_xO_ (40) (x=1-6), H_4PMo_ (11) VO_ (40), H_5PMo_ (10) V_2O_ (40) and H_6PMo_9V_3O_ (40) for acid part, denoted as PMoW and PMo V; with cationic polyelectrolyte, namely poly diallyl dimethyl ammonium chloride (two PDDA) functionalized graphene (PDDA-RGO) as a conductive substrate, through a combination of mixed type polyoxometalates unique redox properties, conductive graphite and PDDA connectivity closely ene good, three yuan of POM-PDDA-RGO composite material can effectively avoid the solubility of more acid in the electrolyte, and in acidic electrolyte (1 mol L~ (-1) H_2SO_4 solution) showed excellent electrochemical performance. Using PMo W-PDDA-RGO as an example, shows high specific capacity, good rate capability (in 10 A g~ (-1) high current density than the capacity of 140 F g~ (-1)), stable cycle performance (5 A g~ (-1) under after 1700 cycles the capacity retention rate was 94.6%) and high energy density. The composite materials in 250 W kg~ (-1) of the power density. 6.15W H kg~ (-1) and the energy density of.2. by hydrothermal method in one step to achieve more dopamine acid assisted in situ polymerization, and prepared a series of composites based on PMo_ acid and poly dopamine (11) V/PDA, PMo_ (10) in situ acid assisted V_2/PDA and PMo_9V_3/PDA. for the polymerization synthesis the complex it polydopamine acid and has a certain universality. Polydopamine as a kind of biomimetic polymer material with properties and adhesion of electron transfer is unique, and has multiple step redox properties of Keggin type Mo/V mixed heteropoly acid combination showed good electrochemical activity and stability, and as a success No high performance lithium ion battery cathode material binder. The composite material as electrode active material content is 80 wt%, showed good electrochemical performance. The electrochemical test results showed that PMoV/PDA composite material with high discharge capacity, excellent rate and long times cycle stability: PMo_ (10) V_2/PDA for example, the first round of the discharge capacity of 1654 mA h g~ (-1), the corresponding rate was 66.5% in Kulun; the high current density of 2000 mA g~ (-1) of the discharge capacity reached 559.6 mA h g~ (-1); in 100 mA g~ (-1) after 65 cycles under discharge the capacity of almost no attenuation, remained at 915.3 mA h g~ (-1), Kulun efficiency reached above 99%. In the high current density of 1000 mA g~ (-1) conditions, after 300 cycles the capacity retention rate of 93%, Kulun efficiency can reach more than 99%.3 with isopolymolybdate Na_6Mo_7O_ (24), by a step Ball milling method, and conductive carbon black acetylene cheap (AB) composite was prepared, Na_6Mo_7O_ (24) /AB nano composite materials. The Na_6Mo_7O_ (24) /AB composite material as cathode material for sodium ion batteries and its electrochemical performance was studied. Experimental results show that with pure Na_6Mo_7O_ (24) compared to Na_6Mo_7O_ (24) the electrochemical properties of /AB composites increased significantly, indicating that seven sodium molybdate has good application prospect in the sodium ion batteries, but also broaden the application of isopolyacid in electrochemical energy storage in the field.

【学位授予单位】：东北师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB33;O646

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