【作者】 王毅；

【导师】 杨文胜；

【作者基本信息】 北京化工大学 ， 应用化学， 2009， 博士

【摘要】 本论文以发展层状双羟基复合金属氧化物（LDHs）电化学功能材料为目标,采用多种技术手段制备了一系列LDHs纳米粉体及LDHs基纳米结构薄膜。采用X射线衍射（XRD）、电感耦合等离子体原子发射光谱（ICP-AES）、傅立叶变换红外光谱（FT-IR）、拉曼光谱（Raman）、X射线光电子能谱（XPS）、热重-质谱联用（TG-MS）、透射电镜（TEM）、高分辨透射电镜（HR-TEM）、场发射扫描电镜（FE-SEM）、扫描隧道显微镜（STM）和电化学测试等表征手段对合成产物组成结构、电极反应机理以及材料组成结构与电化学性能之间的关系进行了较深入的研究。主要研究工作和结论如下:1、采用成核晶化隔离法制备了粒径分布均一的不同Co/Al比的碳酸根插层Co-Al LDHs。系统研究了焙烧处理温度和Co/Al比对其组成、微观形貌、比表面积、晶体结构和电化学性能的影响。Co/Al比为2的Co-Al LDHs在160℃焙烧处理后仍能保持层状结构,且Co电化学活性位得到充分暴露。其比电容达684 F·g^-1,并具有良好的倍率特性和电化学循环稳定性。这种材料在超级电容器电极材料中具有应用价值。2、采用电泳沉积技术制备了Mg-Al LDHs薄膜。将Mg-Al LDHs纳米颗粒分散在无水乙腈中制备悬浮液,在直流电场作用下,表面带有正电荷的Mg-Al LDHs纳米颗粒将向氧化铟锡导电玻璃（ITO）阴极定向迁移并沉积形成Mg-Al LDHs薄膜。系统考察了电泳沉积时间和电压以及悬浮液浓度对薄膜沉积量和微观形貌的影响。在相同浓度的悬浮液和相同沉积时间内,薄膜沉积量随施加电压的增大而增大;在相同电压条件下,薄膜沉积量随沉积时间的延长而增大;而在相同沉积电压和时间下,薄膜沉积量随悬浮液浓度的增大而线性增大。3、采用电泳沉积技术制备了Co-Al LDHs/多壁碳纳米管（MWCNTs）复合薄膜。将表面带有正电荷的Co-Al LDHs纳米颗粒和表面带有负电荷的MWCNTs分散在无水乙腈中后,由于二者之间的静电自组装将形成带有正电荷的Co-Al LDHs/MWCNTs复合颗粒。在直流电场作用下,向ITO阴极定向迁移并沉积形成Co-AlLDHs/MWCNTs复合薄膜。得益于MWCNTs的加入,该复合薄膜的倍率特性和电化学循环稳定性明显得到改善。4、采用电泳沉积技术,利用Zn-Al LDHs纳米片作为构建模块,在ITO基片上制备了Zn-Al LDHs纳米球薄膜。薄膜形貌可以通过控制沉积时间加以调控。进一步的焙烧处理可以制备Zn-Al复合金属氧化物（MMO）纳米球薄膜。形成这种纳米球结构的原因是在电泳沉积过程中,作为剥层溶剂的甲酰胺会发生电解反应生成类金刚石（DLC）前体,Zn-Al LDHs纳米片以其为晶核组装成纳米球。5、采用溶剂蒸发法,以具有电化学活性的LDHs纳米片作为构建模块,在ITO基片上制备了连续高取向的LDHs纳米片薄膜电极材料。系统研究了Al含量、薄膜厚度和焙烧处理温度对Co-Al LDHs纳米片薄膜电极材料电化学性能的影响。Co/Al比为3的薄膜电极材料比电容高达2500 F·cm^-3(833 F·g^-1),且具有好的倍率特性和优异的循环稳定性,是一类高性能薄膜超级电容器电极材料。通过对Ni-AlLDHs纳米片薄膜电极材料的电化学性能研究发现,该薄膜电极材料的电极反应受质子扩散控制,其质子扩散系数高(1.92×10^-9 cm²·s^-1)。按Ni计算其比容量达660 mAh·g^-1,且具有好的倍率特性和循环稳定性,是一类高功率型Ni-MH电池电极材料。更多还原

【Abstract】 In this paper,we are trying to develop the application of Layered Double Hydroxides（LDHs） in electrochemistry.Based on this conception, a series of powdery LDHs nanomaterials and LDHs based nanostructured thin films have been synthesized by a variety of techniques.Structure and composition of the synthesized materials,electrode reaction mechanisms, the relationships among structure,composition and electrochemical properties of materials were characterized by means of XRD,ICP-AES, FT-IR,Raman,XPS,TG-MS,TEM,HR-TEM,FE-SEM,STM and electrochemical test.The main results are as follows:1.Co-Al LDHs have been synthesized by a method involving separate nucleation and aging steps.The effects of thermal treatment and Co/Al mole ratio on their microscopic morphology,surface area, crystal structure,and electrochemical behavior have also been investigated.The Co-Al LDHs with the Co/Al ratio of 2:1 retain a layered structure up to 160℃and the electrochemically active Co sites become increasingly exposed.This material obtained by heating at 160℃exhibited supercapacitor behavior with a high specific capacitance of 684 F·g^-1,a good high-rate capability,and an excellent electrochemical stability.This material can be used as electrode material for supercapacitors.2.Mg-Al LDH films have been fabricated by an electrophoretic deposition（EPD） method.The Mg-Al LDH nanoparticles were dispersed in pure acetonitrile medium to prepare the suspension solution.By applying a positive voltage,the positively charged Mg-Al LDH nanoparticles moved towards the conductive indium tin oxide（ITO）-coated glass cathode and deposited on it.A kind of Mg-Al LDH films can be obtained.The effects of EPD parameter, sucha as voltage,time,and suspensiosn concentration,have also been investigated.The deposition weight increases with the time for the same voltage and suspension concentration;the deposition weight increases with the EPD voltage for the same time and suspension concentration;the deposition weight increases linearly with the suspension concentration for the same votage and time.3.A novel Co-Al LDHs/multiwall carbon nanotubes（MWCNTs） composite film has been fabricated on the ITO substrate via an EPD method.EPD of two different charged nanoparticles,the positively charged Co-Al LDHs nanoparticles and the negatively charged MWCNTs,has been achieved due to the self-assembly of the Co-Al LDH nanoparticles to the surface of the MWCNTs.The further electrochemical investigations show that the composite films have better high-rate capability and longer cycle life than those without MWCNTs,which can be attributed to the adding of MWCNTs.4.A novel Zn-Al LDH nanosphere film has been fabricated on an ITO substrate using Zn-Al LDH nanosheets as building blocks via an EPD method.The morphology of the as-deposited films can be tailored by adjusting the deposition time and a Zn-Al mixed metal oxide（MMO） can be obtained by further heat treatment.We propose that the novel nanosphere microstructure results from the formation of diamond like carbon（DLC） precursor material,by electrolytic decomposition of formamide during the EPD process,which precipitates the Zn-Al nanosheets to lead to nuclei which develop into nanospheres.5.A serious of novel highly oriented and continuous LDH nanosheet thin film electrode materials have been fabricated using electrochemical active LDH nanosheets as building blocks by a simple evaporation method.The effects of varying the Al content,the film thickness,and the heating temperature on the electrochemical properties of the as-deposited Co-Al LDH nanosheet thin film electrode materials have been investigated.A thin film electrode material with a Co/Al molar ratio of 3:1,which has a large specific capacitance of 2500 F·cm^-3(833 F·g^-1),a good high-rate capability, and an excellent electrochemical stability,shows the best performance when used as an electrode material for thin film supercapacitors.The electrochemical investigations show that the electrode reaction of the Ni-Al LDH nanosheet thin film electrode material is controlled by proton diffusion and a high proton diffusion coefficient of 1.92×10^-9 cm²·s^-1 can be obtained.A high specific capacity of 660 mAh·g^-1 of Ni, an excellent high-rate capability,and a good electrochemical stability have also been obtained.This kind of thin film electrode material made up of Ni based LDH nanosheets may be an alternative electrode material for Ni-MH battery that can prove high energy density even at high-power specifications.更多还原