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首页> 外文会议>Massive Energy Storage for the Broader Use of Renewable Energy Sources 2013 >FINE METAL-OXIDE NANOPARTICLES PREPARED BY ELECTROSPRAYING METHOD: APPLICATIONS IN ENERGY STORAGE
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FINE METAL-OXIDE NANOPARTICLES PREPARED BY ELECTROSPRAYING METHOD: APPLICATIONS IN ENERGY STORAGE

机译：喷涂法制备的金属氧化物纳米微粒：在能源存储中的应用

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The fine metal-oxide nanoparticles gain attention in wide range of applications, for example, in medical solutions, in environmental protection, in sanitation and most importantly in electrochemistry. Electrospraying technique allows us to prepare well defined layers of particles at the nano-scale. In this study several methods for preparation of the nano-structured layers of MnO_2 and Co_3O_4 oxides are presented. The MnO_2 layers find their application in pseudocapacitors, i.e., devices with theoretical capacitance up to 1100 C/g. The conditions during deposition process were optimized with respect to the final layer morphology (porosity, particle size), which was studied by AFM and SEM techniques. Once the satisfactory morphology was obtained, the composition of the produced layers was analyzed by XRD and Raman microscopy. The measurements showed that the deposited layer is consisted of mixed manganese oxides (including Mn_3O_4). To convert this mixture to MnO_2 the effects of annealing and electrochemical cycling on the composition were studied. Annealing in air for 3 to 6 hours at temperatures from 300 to 600℃ was studied. After annealing at moderate temperatures (300 to 400℃) we observed an increase in Mn_3O_4 content. At temperatures above 500℃, the material was oxidized to Mn_2O_3 with a possible small fraction of Mn_5O_8. Change in the annealing time from 3 to 6 hours hasn't significantly affected the observed phenomena. The layer conditioning by electrochemical cycling does result in the change of the deposited material to MnO_2. After 500 cycles the electrode already contains a significant fraction of MnO_2 with the structure of sintered fibers (Figure 1). The change of the electrochemical response after 2 to 200 cycles is shown in Figure 2. The prepared nanostructured electrodes containing MnO_2 were used for supercapacitor assembly. Assembled supercapacitors were subjected to charge/discharge cycling and cycling voltammetry. The specific capacities evaluated by both methods lie between 130 and 150 F per gram of the manganese oxide, which are values consistent with those reported for supercapacitors in the literature. The CO_3O_4 shows the so-called bifunctional catalyst behavior for the oxygen reduction and oxygen evolution reaction, finding its application in air electrodes for fuel cells and metal-air batteries. The combined wet spraying and electrospraying method was developed and successfully applied for the preparation of the air electrodes for metal-air battery. The influence of the catalyst composition, the catalyst particle size and the active layer structure to catalyst activity, the oxygen reduction and the evaluation potentials and the electrode long term stability was studied. The Co, Ni and Mn precursors were used for the catalyst layer deposition and the catalyst composition was verified using Raman microscopy. Prepared electrodes were characterized by the cyclic voltammetry and the electrochemical impedance spectrometry. From the obtained results we can conclude that a zinc-air battery with more than 65% energy efficiency can be developed. The presented study shows that the electrospraying method is a simple tool to prepare a well-defined layers of the active materials with comparable or better parameters for applications in the energy storage technologies.
机译：细金属氧化物纳米颗粒在广泛的应用中引起了关注，例如在医疗解决方案，环境保护，卫生和最重要的电化学领域。电喷雾技术使我们能够在纳米级制备定义明确的颗粒层。在这项研究中，提出了几种制备MnO_2和Co_3O_4氧化物纳米结构层的方法。 MnO_2层可用于伪电容器，即理论电容高达1100 C / g的设备。针对最终层的形态（孔隙度，粒径），对沉积过程中的条件进行了优化，并通过AFM和SEM技术对其进行了研究。一旦获得令人满意的形态，就通过XRD和拉曼显微镜分析所产生的层的组成。测量表明，沉积层由混合的锰氧化物（包括Mn_3O_4）组成。为了将该混合物转化为MnO_2，研究了退火和电化学循环对组合物的影响。研究了在300至600℃的温度下在空气中退火3至6个小时。在中等温度（300至400℃）下退火后，我们观察到Mn_3O_4含量增加。在高于500℃的温度下，该材料被氧化成Mn_2O_3，其中可能含有少量的Mn_5O_8。退火时间从3到6小时的变化并没有显着影响观察到的现象。通过电化学循环进行的层调节确实导致沉积的材料变为MnO_2。经过500次循环后，电极已经含有相当一部分具有烧结纤维结构的MnO_2（图1）。图2显示了2到200个循环后电化学响应的变化。制备的含MnO_2的纳米结构电极用于超级电容器组装。将组装好的超级电容器进行充电/放电循环和循环伏安法。两种方法评估的比容量在每克氧化锰130至150 F之间，该值与文献中报道的超级电容器一致。 CO_3O_4显示了用于氧还原和氧释放反应的所谓双功能催化剂行为，发现其在燃料电池和金属空气电池的空气电极中的应用。开发了湿喷与电喷相结合的方法，并成功地用于金属-空气电池的空气电极的制备。研究了催化剂组成，催化剂粒径和活性层结构对催化剂活性，氧还原量和评估电势以及电极长期稳定性的影响。将Co，Ni和Mn前体用于催化剂层沉积，并使用拉曼显微镜检查验证催化剂组成。制备的电极通过循环伏安法和电化学阻抗谱进行表征。从获得的结果可以得出结论，可以开发出能量效率超过65％的锌空气电池。提出的研究表明，电喷雾方法是一种简单的工具，可以制备出具有可比或更好的参数的明确定义的活性材料层，以用于储能技术。

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