锌空气燃料电池性能影响因素及性能衰减机理研究

发布时间：2018-02-23 04:19

本文关键词： 锌空气燃料电池衰减机理空气电极孔隙再生锌粒再生　出处：《清华大学》2015年博士论文　论文类型：学位论文

【摘要】：锌空气燃料电池(ZAFC)具有燃料存储携带方便、成本低及安全无污染等优点,将其用作离网电源及汽车电源具有广阔前景。开展ZAFC性能影响因素及性能衰减机理研究,是提升其功率密度和使用寿命的必要工作,可为科学设计及合理使用ZAFC提供重要依据。本文提出了一种ZAFC方案,以锌颗粒为燃料,以Mn O2为催化剂。采用开放式阳极室以利于电池堆各节电池内燃料和电解液的均匀分配,采用电解液循环将反应产物从电池中携带出来,通过阳极室结构优化保障了反应区有效面积,通过电极采电方案的优化降低了电池内阻。实验结果表明,燃料电池功率密度可达到435 mW/cm2,相当于一般ZAFC性能的2倍以上;进一步研究了电解液温度、流量及氧气分压对电池性能的影响规律,优化后ZAFC在供气为空气和纯氧时功率密度分别达544 mW/cm2和899 mW/cm2,而且动态响应时间为毫秒级,无电压超调现象。进行了ZAFC性能衰减机理研究。建立ZAFC等效电路模型,进行交流阻抗分析,得知ZAFC使用过程中的性能衰减在于空气电极传荷阻抗及传质阻抗的增大;通过SEM形貌及气体渗透率分析,揭示出性能衰减机理为空气电极的催化剂流失和疏水透气层孔隙堵塞;通过停放实验,发现干式停放时存在锌粒结块及阳极膨胀现象,湿式停放时电解液的腐蚀作用使空气电极疏水性降低及孔隙结构变化,并发现空气电极两侧分别用电解液和去离子水浸没时有水穿越空气电极向电解液侧迁移的现象,可用于重新再生空气电极中被堵塞的孔隙。开发了包含控制单元的ZAFC系统,通过多次启停实验验证了该方案的可行性,并研究了锌粒电解直接制备技术,成功电解出致密的锌颗粒。本文的创新性研究成果极大的提升了ZAFC的功率密度,揭示了ZAFC的性能影响因素及性能衰减机理,实现了空气电极孔隙再生和锌粒再生技术,为ZAFC的科学设计提供了理论指导,并为其商业化应用提供了技术基础。
[Abstract]:Zinc air fuel cell (ZAFC) with fuel storage and portability, low cost and no pollution, which is used as power supply and auto power off network has broad prospects. To carry out the study on the mechanism of attenuation performance and factors influence on the performance of ZAFC, is necessary to enhance its power density and service life, and can provide an important basis for the scientific design and reasonable use of ZAFC. This paper proposes a ZAFC scheme with zinc particles as fuel, with Mn O2 as catalyst. The open type anode chamber to each battery in the fuel cell stack and the uniform distribution of the electrolyte, electrolyte circulation will carry out the reaction product from the battery, by optimizing the structure of anode chamber ensure the effective area of the reaction zone, reduce the internal resistance of the battery by optimizing the electrode electric scheme. Experimental results show that the fuel cell power density can reach 435 mW/cm2, equivalent to the general performance of ZAFC More than 2 times; further study of the electrolyte temperature, flow rate and oxygen partial pressure influences the performance of the battery, the optimized ZAFC in gas supply for air and oxygen when the power density reached 544 mW/cm2 and 899 mW/cm2, and the dynamic response time in millisecond, no voltage overshoot phenomenon. The ZAFC performance degradation mechanism Study on the establishment of ZAFC equivalent circuit model of AC impedance analysis, that the performance of ZAFC used in the process of decay is increased and the air electrode charge transfer impedance and mass transfer impedance; through the SEM morphology and gas permeability analysis, reveals the performance degradation mechanism for the loss of catalyst of air electrode and hydrophobic breathable layer pore clogging; through the parking experiment found dry parking zinc agglomerate and the anodic corrosion of wet expansion phenomenon, parking the electrolyte hydrophobic air electrode decreased and the change of pore structure, and found it empty Gas electrodes on both sides respectively with electrolyte and deionized water immersion when water through the air electrode migration to the electrolyte side phenomenon, can be used to regenerate the blocked air electrode porosity. The development contains the ZAFC system control unit, through repeated on-off experiment verify the feasibility of the scheme, and study the direct preparation of electrolytic zinc particle the preparation technology, the success of electrolytic zinc particles dense. This innovative research results greatly enhance the power density of ZAFC, reveals the impact of the performance of ZAFC factors and attenuation mechanism of the air electrode pore regeneration and zinc particle regeneration technology, provides a theoretical guidance for the scientific design of ZAFC, and provides technology the foundation for its commercial application.

【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TM911.41

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