Electric Response and Conductivity Mechanism in H3PO4‑Doped Polybenzimidazole-4N−HfO2 Nanocomposite Membranes for High Temperature Fuel Cells
Electric Response and Conductivity Mechanism in H3PO4‑Doped Polybenzimidazole-4N−HfO2 Nanocomposite Membranes for High Temperature Fuel Cells
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DOI：
10.1016/j.electacta.2016.12.151
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发表时间：
2017-02
影响因子：
6.6
通讯作者：
G. Nawn;K. Vezzù;Federico Bertasi;Gioele Pagot;G. Pace;F. Conti;E. Negro;V. Noto
中科院分区：
文献类型：
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作者：
G. Nawn;K. Vezzù;Federico Bertasi;Gioele Pagot;G. Pace;F. Conti;E. Negro;V. Noto
采用动态力学分析（DMA）和宽带电谱（BES）研究了用于高温质子交换膜燃料电池的磷酸掺杂[PBI4N(HfO2)x](H3PO4)ynano复合膜的弛豫和极化现象。该膜是通过浇注聚苯并咪唑聚合物 (PBI4N) 与增加量的氧化铪纳米填料的组合而获得的，从而形成 0 ≤ x ≤ 0.32 的 [PBI4N(HfO2)x] 杂化系统。使用不同含量水平 (0 ÷ 18 wt%) 的磷酸作为掺杂剂，产生 [PBI4N(HfO2)x](H3PO4)y 膜。 DMA 和 BES 研究使我们确定膜的电响应是由极化现象以及聚合物基质的 α 和 β 介电弛豫事件调节的。此外，实验结果表明，在[PBI4N(HfO2)x](H3PO4)y膜中，导电性的发生是由于三种导电途径：两种通过“跳跃”事件涉及域间质子迁移现象的机制；以及两种通过“跳跃”事件涉及域间质子迁移现象的机制。以及离域体之间发生质子交换的一种机制。这些结果强调了氧化铪纳米填料含量对 [PBI4N(HfO2)x](H3PO4)y 电导率的显着影响，其中，在 x ≥ 0.04 时，电导率 (9.0 × 10−2S/cm) 高于原始 H3PO4 掺杂的 PBI4N (4.8 × 10−2S/cm) 在 T ≥ 155 °C 时的电导率。
Relaxation and polarization phenomena of phosphoric acid-doped [PBI4N(HfO2)x](H3PO4)ynanocomposite membranes for high-temperature proton-exchange membrane fuel cells are studied using Dynamic Mechanical Analysis (DMA) and Broadband Electrical Spectroscopy (BES). The membranes are obtained by casting combinations of a polybenzimidazole polymer (PBI4N) with increasing amounts of hafnium oxide nanofiller, resulting in [PBI4N(HfO2)x] hybrid systems with 0 ≤ x ≤ 0.32. Phosphoric acid at varying content levels (0 ÷ 18 wt%) is used as a doping agent, giving rise to [PBI4N(HfO2)x](H3PO4)ymembranes. DMA and BES studies lead us to determine that the electric response of the membranes is modulated by polarization phenomena and by α and β dielectric relaxation events of the polymer matrix. Additionally, the experimental results suggest that in [PBI4N(HfO2)x](H3PO4)ymembranes the conductivity occurs owing to three conductivity pathways: two mechanisms involving inter-domain proton migration phenomena by “hopping” events; and one mechanism in which proton exchange occurs between delocalization bodies. These results highlight the significant effect of the hafnium oxide nanofiller content on the conductivity of [PBI4N(HfO2)x](H3PO4)ywhere, at x ≥ 0.04, demonstrates conductivity higher (9.0 × 10−2S/cm) than that of pristine H3PO4-doped PBI4N (4.8 × 10−2S/cm) at T ≥ 155 °C.