锌空电池多孔气体扩散电极内液体界面运动规律

发布时间：2017-12-27 23:28

本文关键词：锌空电池多孔气体扩散电极内液体界面运动规律　出处：《中国科学技术大学》2016年硕士论文　论文类型：学位论文

【摘要】：电池在当今社会发挥着重要作用,其中锌空电池因其大容量无污染等诸多优势得到广泛关注。锌空电池的气体扩散电极作为氧气的反应场所是锌空电池的关键技术。当前主要使用的气体扩散电极是孔径尺度在1微米左右的多孔介质,气体扩散电极在高电流密度条件下工作时,电流密度又主要由空气、电解液和电极材料共同组成的气液固三相交界线处提供。本文在前人研究的基础上,做出了以下四个方面的创新研究工作：1.通过实验测定了泡沫镍骨架气体扩散电极浸液质量与放电伏安曲线和峰值功率的对应关系,发现电极放电性能变化可以分为三个阶段：干燥气体扩散电极开始工作后放电性能先小幅增加,在浸液2小时后达到最佳性能,2-24小时,峰值功率逐渐衰减到刚开始的75%,总体尚处在可有效工作水平；24小时后,放电性能随浸液量增加快速下降,直到96小时后基本不再衰减,此时峰值功率只有最开始的27%；同时发现实验电极浸液量变化规律近似一条对称轴为时间轴的二次曲线,并通过推导圆柱形单管中电解液在毛细力驱动下的推进过程,得到电解液界面在单管中推进的近似规律,二者对比后发现,实验测量结果与近似理论推导的单管中液体变化规律一致,2.通过将气体扩散电极电镜照片网格化,转化成四通道二维拓扑网格,通过数值模拟近似描述了电解液界面在多孔电极中的推进过程。发现电解液界面推进过程中,形成的气液固三相交界线总长度也会经过先增长再逐渐缩短的过程,与实验现象一致,从而对电极放电性能变化规律作出合理解释,认为电极放电性能和气液固三相交界线总长度直接相关。3.通过改变电极骨架结构的实验,发现电解液主要沿着电极骨架快速推进。因此,从骨架结构入手初步设计了压皮电极和疏水化预处理骨架表面的两种电极,有效的减缓了电解液界面推进过程,但由于导电性下降等原因,导致放电性能有所下降。该方向探索处于起步阶段,继续深入研究有望得到放电性能更好,持续时间更长的气体扩散电极。4.通过采用一种数字图像的处理方法,将气体扩散电极内部各材料分布规律和连通性规律可视化。了解了由多种粉末状材料按一定配比比例混合组成的电极材料内部各种成分的分布规律。并通过实验验证了该方法的合理性和可行性。
[Abstract]:Battery plays an important role in today's society, and zinc space battery has been widely concerned because of its large capacity and no pollution and many other advantages. The gas diffusion electrode of zinc air battery as the reaction place of oxygen is the key technology of the zinc air battery. The gas diffusion electrode currently used is a porous medium with aperture size of about 1 microns. When the gas diffusion electrode is working under high current density, the current density is mainly provided by the gas-liquid solid three intersecting line consisting of air, electrolyte and electrode materials. On the basis of previous research, make the innovation research on the following four aspects: relationship between 1. tested nickel foam skeleton extract quality and discharge gas diffusion electrode voltammetry and peak power, electrode discharge performance changes can be divided into three stages: dry gas diffusion electrode to work after discharge performance to increase slightly, to achieve the best performance, in 2 hours 2-24 hours after infusion, the peak power will decay to the beginning of 75%, the overall level is still in the works; 24 hours later, the discharge performance declined rapidly with the infusion amount increased until 96 hours after the basic no longer decay, the peak power is only the beginning of the 27%; at the same time found the changes of experimental electrode immersion momentum approximation to a symmetry axis is two times curve time axis, and the electrolyte through the derivation in the capillary driven cylindrical tube The advance process, the approximate rule of electrolyte interface in a single tube push, the two comparison found that the experimental results consistent with the variation of liquid tube and approximate theoretical deduction, 2. through the gas diffusion electrode electron microscope grid, into four channels of two dimensional grid topology, through numerical simulation of approximate description of propulsion the process of electrolyte interface in the porous electrodes. Found the electrolyte interface in the process of advancement, the formation process of the gas liquid solid three phase boundary will pass to the total length of growth gradually shortened, consistent with the experimental phenomenon, so as to make a reasonable explanation to the variation of electrode discharge performance, it is considered that the electrode discharge performance and gas liquid solid three-phase to the total length of line is directly related to. 3. through the experiment of changing the structure of the electrode skeleton, it was found that the electrolyte was mainly propelling along the electrode skeleton. Therefore, starting from the skeleton structure, two electrodes, namely, the skin pressure electrode and the hydrophobic pretreatment skeleton surface, were initially designed, which effectively slowed down the electrolyte interface propulsion process, but the discharge performance decreased due to the decrease of conductivity. The exploration of this direction is in the initial stage and continues to study the gas diffusion electrode which is expected to have better discharge performance and longer duration. 4. by using a digital image processing method, the distribution and connectivity of each material in the gas diffusion electrode are visualized. The distribution of various components in the electrode material made up of a certain proportion of powder materials according to a certain proportion is understood. The rationality and feasibility of the method are verified by experiments.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM911.41

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