Influence of binder properties on kinetic and transport processes in polymer electrolyte fuel cell electrodes
Influence of binder properties on kinetic and transport processes in polymer electrolyte fuel cell electrodes
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DOI：
10.1039/b921916a
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发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
Ramani, Vijay
中科院分区：
文献类型：
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作者：
Sambandam, Satheesh;Ramani, Vijay
本研究的目的是估计的贡献动力学，欧姆和传质过电位的聚合物电解质膜燃料电池（PEMFC）电极的整体电压损失，并与这些过电位电极粘合剂的性能，如离子电导率，离子交换容量（IEC）和O-2渗透性。研究的模型电极粘合剂是全氟磺酸离聚物（PFSA; IEC 1.35 meq g（-1）和0.95 meq g（-1））、磺化聚醚醚酮（SPEEK; IEC 1.35、1.75和2.1 meq g（-1））和磺化聚砜（SPSU; IEC 1.5 meq g（-1））。在80 ℃和75%RH下，这些粘合剂的O-2渗透性从SPSU的0.15 x 10（-12）mol cm（-1）s（-1）到PFSA IEC的6 x 10（-12）mol cm（-1）s（-1）不等，0.95 meq g（-1）。通过循环伏安法对所制备的电极进行表征，以估计铂的电化学活性表面积（ECA）。稳态极化（V-I）实验以氢为燃料，氧化剂包括O-2、21%O-2/N-2（空气）、21%O-2/He（Helox）和4%O-2/N-2。分析所获得的V-I数据以确定电极中不同极化源的相对贡献。使用PFSA粘合剂制备的电极具有28 m（2）g（-1）-Pt的类似ECA，而使用烃粘合剂制备的电极在80 ℃和75%RH下具有10至14 m（2）g（-1）-Pt的ECA。在群众活动中也出现了同样的趋势。在优化的粘合剂负载，半定量的关系，得到相关的粘合剂O-2渗透性的电极内的传质损失。此外，一种新的半定量的方法绘制螺旋空气电压增益对O-2-空气增益探测O-2传输限制的电极。基于此分析，有人建议，SPEEK和SPSU绑定电极遭受粘合剂相扩散限制，除了气相扩散限制，而PFSA绑定电极主要表现出气相扩散限制。
The objectives of this study are to estimate the contributions of kinetic, ohmic and mass transport overpotentials to the overall voltage loss in polymer electrolyte membrane fuel cell (PEMFC) electrodes and to relate these overpotentials to electrode binder properties such as ionic conductivity, ion exchange capacity (IEC) and O-2 permeability. The model electrode binders studied were perfluorosulfonic acid ionomers (PFSA; of IECs 1.35 meq g(-1) and 0.95 meq g(-1)), sulfonated poly ether ether ketone (SPEEK; of IECs 1.35, 1.75 and 2.1 meq g(-1)) and sulfonated poly sulfone (SPSU; of IEC 1.5 meq g(-1)). The O-2 permeability of these binders varied from 0.15 x 10(-12) mol cm(-1) s(-1) for SPSU to 6 x 10(-12) mol cm(-1) s(-1) for PFSA IEC 0.95 meq g(-1) at 80 degrees C and 75% RH. The electrodes prepared were characterized by cyclic voltammetry to estimate electrochemically active surface area (ECA) of platinum. Steady state polarization (V-I) experiments were performed with hydrogen as fuel and oxidants including O-2, 21% O-2/N-2 (air), 21% O-2/He (Helox) and 4% O-2/N-2. The V-I data obtained was analyzed to determine the relative contributions of the different sources of polarization in the electrode. Electrodes prepared with PFSA binders had similar ECAs of 28 m(2) g(-1)-Pt, while those prepared using hydrocarbon binders had an ECA of 10 to 14 m(2) g(-1)-Pt at 80 degrees C and 75% RH. The same trend was seen in mass activity. At optimized binder loadings, a semi-quantitative relationship was obtained relating binder O-2 permeability to the mass transport losses within the electrode. Furthermore, a novel semi-quantitative method of plotting helox-air voltage gain against O-2-air gain was employed to probe the O-2 transport limitations in the electrodes. Based on this analysis, it is suggested that the SPEEK and SPSU bound electrodes suffered from binder phase diffusion limitations in addition to gas phase diffusion limitation, while the PFSA bound electrodes predominantly exhibited gas-phase diffusion limitations.