铝空气电池电解液和循环系统的研究

发布时间：2018-01-29 20:43

  本文关键词： 铝空气电池 电解液 放电产物 添加剂 循环系统　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：铝空气电池是一种具有巨大潜力的金属空气电池,它的能量密度远高于锂离子电池,它还具有其它二次电池无法比拟的优点,当电池中铝消耗完,可以通过更换铝板实现“机械式充电”,从而减少了“充电”时间,并且铝价格低廉,来源广泛,铝空气电池因此引起了人们的关注。然而制约铝空气电池长时间使用的因素之一是铝空气电池放电产物处理问题,铝电极在放电过程中,其反应产物为NaAlO_2,当NaAlO_2在电解液中达到一定浓度时便会析出Al(OH)3,在电解液中不易直接滤除,从而会带来一系列严重的问题。首先大量的NaAlO_2会严重影响电解液的黏度和电导率,电解液电导率的下降,会增加铝空气电池的溶液的电阻,电池的放电性能衰减;电解液变粘,严重时呈黏糊状,极大影响电解液使用寿命,不利于放电过程中生成的气体排出和反应物的扩散,并且对铝空气电堆中电解液的循环带来一定的负担。本论文中研究了铝空气电解液中反应产物NaAlO_2对电解液物理性质的改变,分析NaAlO_2浓度对铝电极、空气电极以及电池性能的影响规律,证实电解液中饱和NaAlO_2会使铝空气电池最大功率下降约15%;F-对铝电极的电化学行为有显著的影响,通过使用NaF作为添加剂提升铝电极在电解液中电化学性能从而降低NaAlO_2对铝空气电池的有害影响;此外论文中利用电解铝,分析铝电极在电解液中析出的Al(OH)3颗粒,其颗粒大小集中在1μm到20μm之间,并且使用水力旋流器设计了一套铝空气电解液循环系统,它可以将铝空气电堆在放电过程中生成的Al(OH)3颗粒进行收集,当水力旋流器进口流量的增加,该系统收集Al(OH)3颗粒的能力出现先增大后减小的趋势,当水力旋流器进口流量为0.67 L/min时Al(OH)3颗粒收集率最大30 min内可达84%,整个循环系统的能耗在6 W左右,具有结构简单,能耗少等优点。论文中首次将聚丙烯酰胺(PAM)应用于铝空气电池电解液中,PAM在电解液中的使用可以增加电解液的黏度,但不会改变电解液的电导率,从而不会改变电池内阻并且对空气电极和铝电极电化学性能影响较小。PAM在电解液中具有絮凝作用能加快Al(OH)3颗粒在电解液中的沉降速度,使Al(OH)3颗粒在短时间快速沉降到电解液桶底部从而达到沉降分离;PAM在电解液中具有增稠性,增加电解液的黏度但仍具有较好的流动性,可以将铝空气单体内腔生产的Al(OH)3颗粒粘黏在电解液中,随着电解液的流动全部带出单体内腔,避免Al(OH)3颗粒在单体内腔堆积,极大延长空气电极寿命。
[Abstract]:Aluminum air battery is a kind of metal air battery with great potential. Its energy density is much higher than that of lithium ion battery. "Mechanical charging" can be achieved by replacing aluminum sheets, thus reducing "charging" time, and aluminum is cheap and widely available. However, one of the factors restricting the long-term use of aluminum air battery is the disposal of the discharge product of the aluminum air battery, the aluminum electrode in the discharge process. The product of the reaction is NaAlO2. when NaAlO_2 reaches a certain concentration in the electrolyte, it will precipitate AlOH3, which is not easy to be filtered directly in the electrolyte. First, a large number of NaAlO_2 will seriously affect the viscosity and conductivity of the electrolyte. The decrease of the electrolyte conductivity will increase the resistance of the aluminum air battery solution. The performance attenuation of battery discharge; When the electrolyte becomes sticky, it becomes sticky and paste, which greatly affects the service life of the electrolyte, and is not conducive to the discharge of gases and the diffusion of reactants in the discharge process. And it brings a certain burden to the circulation of electrolyte in the aluminum air stack. In this paper, the change of the physical properties of the electrolyte produced by the reaction product NaAlO_2 in the aluminum air electrolyte has been studied. The effect of NaAlO_2 concentration on the performance of aluminum electrode, air electrode and battery is analyzed. It is proved that saturated NaAlO_2 in electrolyte can decrease the maximum power of aluminum air battery by about 15%. F- has a significant effect on the electrochemical behavior of aluminum electrode. By using NaF as additive, the electrochemical properties of aluminum electrode in electrolyte can be improved to reduce the harmful effect of NaAlO_2 on aluminum air battery. In addition, aluminum electrolysis is used to analyze the Al(OH)3 particles precipitated from aluminum electrode in electrolyte. The size of the particles is between 1 渭 m and 20 渭 m. A set of aluminum air electrolyte circulation system is designed by using hydrocyclone, which can collect the Al(OH)3 particles generated in the discharge process of the aluminum air stack. When the inlet flow rate of hydrocyclone increases, the capacity of collecting Al(OH)3 particles in the system increases first and then decreases. When the inlet flow rate of hydrocyclone is 0.67 L / min, the Al(OH)3 particle collection rate can reach 84% within 30 min, and the energy consumption of the whole circulatory system is about 6 W. It has the advantages of simple structure and less energy consumption. In this paper, the application of PAM in the electrolyte of aluminum air battery for the first time can increase the viscosity of the electrolyte. But it doesn't change the conductivity of the electrolyte. So it can not change the internal resistance of the battery and has little effect on the electrochemical performance of the air electrode and aluminum electrode. The flocculation of Al(OH)3 particles in the electrolyte can accelerate the settling rate of Al(OH)3 particles in the electrolyte. The Al(OH)3 particles can be precipitated to the bottom of the electrolyte bucket in a short time. PAM has thickening property in the electrolyte, increases the viscosity of the electrolyte but still has good fluidity, and can stick the Al(OH)3 particles produced in the inner cavity of aluminum air monomer to the electrolyte. With the flow of electrolyte, the monomeric cavity is brought out, and the accumulation of Al(OH)3 particles in the monomer cavity is avoided, which greatly prolongs the life of air electrode.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.41
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本文编号：1474319