【作者】 上官恩波；

【导师】 常照荣；

【作者基本信息】 河南师范大学 ， 物理化学， 2012， 博士

【摘要】 众所周知，电动车在未来的绿色交通系统中扮演着重要角色，而与之配套的动力电池能否做到高性能低成本是制约其发展的关键。镍氢电池由于具有容量大、高功率、充放电性能优良、对环境友好等一系列独特的优点，而被认为是最具发展潜力的电动车动力电池之一。尽管氢镍电池现在早已成功商业化生产，但随着电动自行车，电动汽车等市场的日益扩大，对于氢镍电池动力性能的要求越来越高，其动力性能的改善成为越来越多研究工作者研究的焦点。同时，为了进一步拓展氢镍电池的使用领域，有必要不断地降低氢镍电池的成本。氢氧化镍由于具有优异的电化学性能而已被广泛地用作氢镍电池的正极活性物质。然而，目前被广泛使用的球形氢氧化镍难以满足动力电池高温和高倍率性能的要求。近年来，各种类型的数码产品如雨后春笋般不断出现，对电池的大电流放电性能提出了更高的要求，传统的碱锰电池已无法满足这样的需求，一种新型的以NiOOH为正极活性物质的锌镍电池由于具有比能量大、比功率大、大电流放电性能好、工作电压高和环境友好等优点，引起了越来越多研究者的关注。随着羟基氧化镍在碱性电池正极中的应用越来越多，研究羟基氧化镍的合成工艺对于绿色化学电源的技术改进和创新具有重要的实质性意义。通常，羟基氧化镍通过化学方法合成。然而，这些化学方法有非常多的反应步骤，生产过程需要消耗大量氧化剂；同时使用强碱溶液，不仅会产生大量废水会对环境造成污染而且产品不容易过滤和洗涤。因此，为了促进锌镍电池的发展非常有必要去改进羟基氧化镍的合成方法和材料性能。本论文是为了解决上述这些问题而展开的，有关研究内容和结果如下：1、碱性氢镍电池非球形Ni(OH)2正极材料采用PAM辅助二次干燥法成功制备出振实密度达到2.32g cm3的非球形氢氧化镍材料。采用XRD、IR、SEM、TG-DTA、Brunauer–Emmett–Teller (BET)测试、激光粒度分析、敲实密度测试、CV、EIS和充放电测试等多种测试方法对样品进行了表征，详细考察了振实密度对于非球形氢氧化镍的物理和电化学性能的影响规律。研究结果表明，采用PAM辅助二次干燥法可以成功制备出振实密度比传统共沉淀法制备的高的多的非球形氢氧化镍样品。随着振实密度的不同，氢氧化镍的物理性能和电化学性能均有较大变化。具有更高密度的氢氧化镍具有更好的电化学活性。新方法制备的样品比传统方法制备的样品具有更高的反应可逆性、更大的质子扩散系数、更低的电荷转移阻抗、更高的放电容量和体积比容量、更好的循环稳定性。这些性能的改善主要归因于高密度非球形材料具有更致密的固态结构、较大的比表面积、更多的结构缺陷、更低的阴离子含量。此外，首次采用PAM辅助二次干燥法制备出Co和Zn共掺杂的高密度非球形氢氧化镍，与具有相同的化学成分和振实密度的商业化的球形氢氧化镍进行了物理性能和化学性能的对比，对氢氧化镍的微结构和表面特性对电化学性能的影响情况进行了研究。研究结果表明，同球形氢氧化镍相比，制备的非球形样品具有不规则的形貌，具有更多的结构缺陷和更大的比表面积，其致密的固态微结构由许多层状的纳米级晶粒组成，从而表现出更优异的电化学性能，包括更高的放电容量和体积比容量、更好的高倍率放电性能。该非球形样品的质子扩散系数达到4.26×109cm2s1。我们相信高密度非球形氢氧氧化镍是一种新的非常有潜力的氢镍电池正极材料。2、碱性锌镍电池NiOOH正极材料对一种在弱碱性溶液(pH=8-13)中电解氧化制备高纯度球形羟基氧化镍的绿色合成方法的反应机理和反应条件进行了探讨，优化了电解工艺，对包括KCl溶液的浓度、pH值、电解电压、温度以及电解时间等工艺参数的影响进行了系统研究。研究结果表明，优化后的电解工艺电解效率高，氧化速度快，而且电解液可以重复使用。即使电解时间充分延长，新方法制备的NiOOH仍是是纯β相。样品不仅拥有良好的电化学性能，而且还有高达2.44g cm3的振实密度。样品在0.2C和3C分别放出256.5，199.1mAh g1的容量，显示出该样品具有的体积比能量可以达到625.86（0.2C），485.80（3C）mAh cm3。在以上实验的基础上，首次采用PAM辅助二次干燥法，传统共沉淀法，控制结晶法三种方法制备出不同的前躯体，然后以其为原料采用电解氧化法制备出羟基氧化镍样品，对不同前躯体对于羟基氧化镍微结构和电化学性能的影响也进行了探索。实验结果表明，采用PAM辅助二次干燥法制备出的前躯体经电解氧化可以成功制备出高密度的非球形羟基氧化镍。该样品的振实密度可以达到2.65g cm3，是目前所知最高的。同球形羟基氧化镍相比，制备的的非球形样品表现出更优异的电化学性能，包括更高的放电容量和体积比容量以及更好的高倍率放电性能。结果还显示，氢氧化镍前躯体的物理性能例如形貌、微结构、振实密度、比表面积等，都极大的影响最终产品的物理和电化学性能。实验结果也表明，高密度非球形羟基氧化镍是一种新的有潜力的锌镍电池正极材料。3、碱性氢镍电池负极放电储备的调整首次提出了一个新颖的使用Ni(OH)x(x=2.1)和γ-CoOOH联合调整氢镍电池负极放电储备的方法。对调整过放电储备的电池进行了系统的测试，同时对Ni(OH)x(x=2.10)和γ-CoOOH对镍电极的电化学性能的影响进行了研究。实验结果表明，Ni(OH)x(x=2.1)和γ-CoOOH的联合使用，不仅可以调整氢镍电池中负极的放电储备到合适的量，极大地减少了负极中合金粉的用量，而且电池的电化学性能得到了明显的改善，尤其是大电流放电性能。具有比较低的放电储备的电池具有较高的放电容量，较好的高倍率放电性能和更稳定的循环寿命。结果显示，这是一个非常有发展潜力地降低氢镍电池的成本和改善氢镍电池性能的新方法。更多还原

【Abstract】 It is well known that the availability of high performance and low cost batteries is an essential factorfor the widespread diffusion of electric vehicles in the mobility system, with important environmentalbenefits. Ni–MH batteries is considered as one of the most promising devices for electric vehicle (EV) andhybrid electric vehicle (HEV) applications because of its high specific energy power and specific energydensity, fast charge and discharge capabilities, environment-friendly characteristics, long cyclic stabilityand good security. Although Ni–MH batteries are commercially available, further research is still requiredto improve their power performance for applications in electric vehicles and hydride vehicles. It is alsonecessary to reduce the cost of Ni–MH batteries in order to further expand their application fields, such asa replacement for nickel–cadmium (Ni–Cd) batteries in power tools. As a result of excellentelectrochemical properties, nickel-based electrode materials have been used in many importantapplications. For example, Ni(OH)2has been intensively studied and used in commercial alkalinerechargeable batteries. However, the common spherical Ni(OH)2can not well meet the demand in electricvehicle battery such as high temperature and current charge and discharge, etc.In recent years, with increasing type and amount of digital products, a new type of alkalineZn-NiOOH battery, which contains NiOOH as the positive electrode material, has attracted worldwideresearch interest because of its high practical specific energy, excellent specific power, high workingvoltage and low toxicity. As a result, there is substantial scientific and technological interest in the study ofNiOOH synthesis due to its extended application in the positive electrodes of alkaline batteries.Conventionally, NiOOH can be easily prepared by a chemical synthetic method. However, the chemicaloxidization method contains many reaction steps, consumes a great deal of reagent, and generates a largeamount of waste effluents. In addition, the products are inconvenient to filtrate and launder due to the useof the strong alkali solution. Hence, it is necessary to improve the synthetic method and performanceimprovement of NiOOH, which are keys for the production of this new type of battery.This thesis is in order to solve the above problems and the results are following：1) Non-spherical Ni(OH)2as positive electrode materials for alkaline Ni-MH batteries Positive electrode active materials of non-spherical nickel hydroxide powders with a high tap-densityfor alkaline Ni-MH batteries have been successfully synthesized using a polyacrylamide (PAM) assistedtwo-step drying method. In this work, we have also studied the effect of tap-density on the electrochemicalperformance of non-spherical Ni(OH)2electrodes. The tap-density of the powders reaches2.32g cm3,which is significantly higher than that of nickel hydroxide powders obtained by the conventionalco-precipitation method. X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electronmicroscopy (SEM), Thermogravimetric/differential thermal analysis (TG-DTA), Brunauer–Emmett–Teller(BET) testing, laser particle size analysis, tap-density testing, cyclic voltammetry (CV), electrochemicalimpedance spectroscopy (EIS), and a charge-discharge test were used to characterize the physical andelectrochemical properties of the synthesized material. The results show that the as-prepared nickelhydroxide materials have an irregular tabular shape, a high density of structural disorder, and a highspecific surface area. The charge-discharge tests indicate that nickel hydroxide powders synthesized by thenew method have better electrochemical performance than those obtained by the conventionalco-precipitation method. This performance improvement could be attributable to a more compact electrodemicrostructure, a lower amount of intercalated anions, better reaction reversibility, a higher protondiffusion coefficient, and lower electrochemical impedance. The results clearly show that betterelectrochemical activity can be achieved using nickel hydroxide that has a higher tap-density.Moreover, we compare the behavior of non-spherical and spherical β-Ni(OH)2as cathode materialsfor Ni–MH batteries in an attempt to explore the effect of microstructure and surface properties ofβ-Ni(OH)2on their electrochemical performances. Non-spherical β-Ni(OH)2powders with a high-densitywere synthesized using a simple polyacrylamide (PAM) assisted two-step drying method. The resultsshow that the non-spherical β-Ni(OH)2materials exhibit an irregular tabular shape and a dense solidstructure, which contains many overlapped sheet nano crystalline grains, and have a high density ofstructural disorder and a large specific surface area. Compared with the spherical β-Ni(OH)2, thenon-spherical β-Ni(OH)2materials have an enhanced discharge capacity, higher discharge potentialplateau and superior cycle stability. This performance improvement could be attributable to a higherproton diffusion coefficient (4.26×109cm2s1), better reaction reversibility, and lower electrochemicalimpedance of the synthesized material. Therefore, it is believed that the non-spherical Ni(OH)2 synthesized by the new method is a promising positive electrode active material for Ni–MH batteries.2）NiOOH as positive electrode materials for alkaline Zn-NiOOH batteriesWe propose a novel electrolysis method to prepare NiOOH by oxidizing spherical Ni(OH)2in adilute alkaline solution (pH=8-13). The effects of preparation conditions, including KCl concentration, PH,constant voltage, temperature and oxidation time, on the synthesis of NiOOH were systematicallyinvestigated. The results show that the electrolytic efficiency and reaction rate are superior and theelectrolyte can be conveniently re-utilized. The results also show that the NiOOH prepared by thiselectrolysis method is with a pure β phase, even if the electrolysis duration is fully prolonged. Thespherical NiOOH sample not only possesses excellent electrochemical activities and provides a dischargecapacity of256.5and199.1mAh g1, and a volume capacity of625.86and485.80mAh cm3at rates of0.2C and3C, respectively, but also has a high tap density of2.44g cm3.Following upon our previous work, nickel oxyhydroxide was synthesized by electrolysis oxidationof different Ni(OH)2precursors, which were prepared by three methods: polyacrylamide (PAM) assistedtwo-step drying (PTSD), conventional co-precipitation (CCP), and “controlled crystallization”(CC). Theeffects of different precursors on the microstructure and electrochemical properties of NiOOH arediscussed in detail. The results demonstrate that the physical and electrochemical properties of NiOOH arestrongly dependent on the properties of the Ni(OH)2precursor, such as its morphology, microstructure, tapdensity, and specific surface area. The results of the electrochemical studies also show that the sampleprepared by the PTSD method is superior to the others in electrochemical performance. The as-prepared,high-density, non-spherical NiOOH is a promising active material for the positive electrode in Zn-NiOOHbatteries.3）Regulation the discharge reservoir of negative electrodes for Ni–MH batteriesA novel strategy to regulate the discharge reservoir of negative electrodes in Ni–MH batteries isinvented by using Ni(OH)x(x=2.10) and γ-CoOOH. The electrochemical measurements of these batteriesdemonstrate that the use of Ni(OH)x(x=2.10) and γ-CoOOH can not only successfully regulate thedischarge reservoir of negative electrodes in Ni–MH batteries to an adequate quantity, but also effectivelyimprove the electrochemical performance of the batteries. Compared with normal batteries, the in-houseprepared batteries with a lower discharge reservoir exhibit an enhanced discharge capacity, improved high-rate discharge ability, higher discharge potential plateau and superior cycle stability. The effect ofNi(OH)x(x=2.10) and γ-CoOOH on the electrochemical performance of nickel electrode is alsoinvestigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The resultssuggest that the new method is simple and effective for cost reduction of Ni–MH batteries with improvedelectrochemical performance.更多还原