PEMFC的自增湿膜电极结构和性能研究

设计并制作了一种新结构的质子交换膜燃料电池(PEMFC)自增湿膜电极。其特点是在催化层和扩散层之间建立水管理层(WML),WML由不同质量比的炭黑和聚四氟乙烯(PTFE)组成双层结构。为了减小气体反应物的扩散传质阻力,在WML的制作过程中加入了具有高分解温度和高溶解度的(NH4)2SO4造孔剂。用单体PEMFC的电流密度-电压曲线评价了膜电极在外增湿和自增湿方式下的极化特性;用环境扫描电子显微镜(ESEM)表征了膜电极的表面形貌和孔结构。实验结果表明,所制备的膜电极具有良好的水管理能力,在较宽的电流区域内具有良好的电化学性能。     

高温PEMFC的性能衰减研究与一维数值模拟

以PBI/H3PO4体系高温质子交换膜燃料电池为研究对象,进行了500h恒负载条件下的连续寿命实验,运用电化学电位扫描技术和交流阻抗技术测试了电池在连续运行过程中的电化学活性面积(AEC)和电池内阻的变化,实验结果表明在500h的连续寿命实验中,电池性能衰减的主要原因是高温操作条件下由于催化剂的烧结造成的电化学活性面积的损失。同时,建立了基于高温体系的一维数学模型,利用电化学方法测试得到的两个重要参数——体交换电流密度和电池内阻作为模型输入参数,计算了电极扩散层的反应气体浓度分布,运用模型模拟了电池在连续寿命实验中不同时间的稳态极化曲线,模拟结果和实验结果基本一致。     

一种奥氏体不锈钢在模拟PEMFC环境中的特性

由于低成本、高强度、易于加工成薄板及其耐蚀性,不锈钢被认为是用做质子交换膜燃料电池(PEMFC)双极板的理想材料。用电化学方法研究了一种奥氏体不锈钢在H2SO4和2mg/LF-水溶液中的腐蚀行为,测量了钝化膜与碳纸间的界面接触电阻。结果表明,这种奥氏体不锈钢在H2SO4和2mg/LF-水溶液中呈现明显的活化-钝化转变,随着H2SO4浓度降低,耐蚀性提高,界面接触电阻增大。     

基于改进型RBF神经网络的PEMFC电特性建模

常规能源短缺的今天,开发利用新型清洁、绿色能源已成为各国科学家共同追求的目标。质子膜燃料电池（PEMFC）以其高功率密度,启动迅速,无污染等优点成为21世纪首选清洁能源系统。但其原理涉及热力学、电化学、流体力学、传质学等理论,形成一个非线性复杂系统,难以建立数学模型。因此,采用一种动态白适应网络即最近邻聚类径向基函数神经网络,它能够动态调节网络的规模和参数,具有较强的逼近能力以及自学习能力。并利用测试数据作为训练样本,在氢气流速给定的条件下,以空气（或氧气）压力和冷却水流速作为模型的输入量,电池的电压为输出量,建立了在工作温度为60℃和80℃时的PEMFC电特性模型。表明该方法具有简单、可行、精度高等优点。并为PEMFC控制系统的设计和电池性能的优化提供了基本依据。     

PEMFC用小型稳压变换器及其监控系统

设计了质子交换膜燃料电池(PEMFC)用稳压变换器及其监控系统.采用Boost、Buck串联拓扑结构为稳压DC/DC 变换器的主电路,对其工作原理进行了分析.介绍了监控系统的监控对象及其参数设定,研制出了样机.试验结果表明,该样机各项技术指标均达到使用要求,工作稳定可靠.     

胶体法制备PEMFC催化剂的评述

胶体法可有效地控制催化剂颗粒的粒径,是制备高Pt负载量催化剂的有效方法.对近几年胶体法制备质子交换膜燃料电池(PEMFC)催化剂的状况进行了评述.按稳定胶体的机理,胶体法可分为无保护剂法和有保护剂法.     

Free vibration analysis of a polymer electrolyte membrane fuel cell

A free vibration analysis of a polymer electrolyte membrane fuel cell (PEMFC) is performed by modelling the PEMFC as a 20 cm × 20 cm composite plate structure. The membrane, gas diffusion electrodes, and bi-polar plates are modelled as composite material plies. Energy equations are derived based on Mindlin's plate theory, and natural frequencies and mode shapes of the PEMFC are calculated using finite element modelling. A parametric study is conducted to investigate how the natural frequency varies as a function of thickness, Young's modulus, and density for each component layer. It is observed that increasing the thickness of the bi-polar plates has the most significant effect on the lowest natural frequency, with a 25% increase in thickness resulting in a 17% increase in the natural frequency. The mode shapes of the PEMFC provide insight into the maximum displacement exhibited as well as the stresses experienced by the single cell under vibration conditions that should be considered for transportation and stationary applications. This work provides insight into how the natural frequencies of the PEMFC should be tuned to avoid high amplitude oscillations by modifying the material and geometric properties of individual components.     

外界供给参数对PEMFC输出性能及水热平衡的影响

为了改善质子交换膜燃料电池(PEMFC)内部的水热平衡,从而进一步改善PEMFC的输出性能,文章建立了PEMFC的三维模型,通过改变PEMFC的外界供给参数(进气速度、加湿率以及冷却水流速),应用COMSOL模拟仿真得到了PEMFC的极化曲线和功率曲线、流道和气体扩散层(GDL)的水浓度分布情况,以及冷却水流速对PEMFC温度的影响。研究结果表明:随着进气速度和加湿率的逐渐增加,PEMFC的输出性能均逐渐提升,但是,过高的加湿率可能导致电极水淹;随着冷却水流速的增加,PEMFC温度加速下降,膜内温度分布变得更均匀。     

The effect of H2S and CO mixtures on PEMFC performance

Proton exchange membrane fuel cells (PEMFCs) most likely will use reformed fuel as the primary source for the anode feed which always contains carbon dioxide (CO) and hydrogen sulfide (H₂S). Trace amount of CO and H₂S can cause considerable cell performance losses. A comparison between the effect of CO and that of H₂S on PEMFC performance was made in this paper. Under the same conditions, the H₂S poisoning rate is much higher than CO because of different adsorption intensity. When the fuel stream contains the gas mixture (25 ppm CO and 25 ppm H₂S), the fuel cell performance deteriorates more quickly than 50 ppm CO but slowly than 50 ppm H₂S and can be only partially recovered by reintroducing neat H₂. The resulting effects of the mixtures can be divided into two parts roughly: during the inception phase, the cell voltage drops quickly and the actual values of anode overvoltage are bigger than the corresponding calculated values; then the deterioration rate of the cell performance decreases gradually.     

Hydrogen sulfide poisoning and recovery of PEMFC Pt-anodes

A simple and effective method for reactivation of H₂S poisoned Pt-anodes is described and the feasibility of the method was examined by single cell tests and 1 kW stack tests. The performance of the H₂S poisoned Pt-anode can be basically recovered by applying a high voltage pulse (1.5 V for 20 s) followed by a low voltage pulse (0.2 V for 20 s) in a single cell. During the 10 poisoning–recovery cycles, the ohmic resistance and electrochemical surface area did not change significantly. The 1 kW stack tests show that the stack performance decayed severely and the maximum power decreased to 0.366 kW (32% of the original value) after exposure to 18 ppm H₂S/H₂ for 2 h at 600 mA cm⁻². The stack performance can be significantly recovered by applying a high voltage pulse (1.5 V for 2 min) followed by a low voltage pulse (0.2 V for 2 min) to each cell. The maximum power recovered to 1.095 kW (97.5% of the original value).