Insights into the performance and degradation of polybenzimidazole/muscovite composite membranes in high-temperature proton exchange membrane fuel cells
Insights into the performance and degradation of polybenzimidazole/muscovite composite membranes in high-temperature proton exchange membrane fuel cells
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DOI：
10.1016/j.memsci.2021.119868
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发表时间：
2021-09-17
影响因子：
9.5
通讯作者：
Holmes, Stuart M.
中科院分区：
文献类型：
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作者：
Guo, Zunmin;Chen, Jianuo;Holmes, Stuart M.
为了提高高温质子交换膜燃料电池（HT-PEMFC）中磷酸（PA）掺杂聚苯并咪唑（PBI）膜的性能和耐久性，采用刮刀法将天然白云母（Mus）作为无机填料成功地掺入到PBI基体中.改变Mus的量（0.5-2重量%）以探索其对复合膜的质子传导率、机械和尺寸稳定性、功率密度、耐久性和酸保持能力的影响。由于将Mus掺入膜中可以引入与聚合物链和PA分子的相互作用，以在Mus-PBI和Mus-PA交联中的界面处提供额外的质子传输途径，因此具有1重量% Mus的膜在150 ℃下没有加湿时显示出586 mW cm（-2）的最高功率密度，比纯PBI膜（474 mW cm（-2））高24%。同时，PA掺杂的复合膜与1重量%的Mus也显示出最高的机械强度（7.5 MPa）和最低的尺寸溶胀（70.99%的面积溶胀和202%的体积溶胀）。与原始PBI膜相比，复合膜在加速应力测试（AST）下具有显著提高的耐久性。AST后欧姆电阻的降低和极化电阻的增加分别与膜变薄和催化剂活性面积的损失有关。最重要的是，发现Mus和PA分子之间的强相互作用导致复合膜的酸保持能力提高，因此从复合膜中浸出的较少的酸减少了对催化剂降解的负面影响，以减轻对电池性能和耐久性的降解。
To improve the performance and durability of phosphoric acid (PA) doped polybenzimidazole (PBI) membranes in high-temperature proton exchange membrane fuel cells (HT-PEMFCs), in this work, as-received natural muscovite (Mus), a clay material, was successfully incorporated into PBI matrix as an inorganic filler through the doctor blade method. The amount of Mus was varied (0.5-2 wt%) to explore its impact on the proton conductivity, mechanical and dimensional stability, power density, durability, and acid retention ability of the composite membranes. As the incorporation of Mus into membranes can introduce interactions with polymer chains and PA molecules to afford additional proton transport pathways at the interfaces in Mus-PBI and Mus-PA crosslinks, the membrane with 1 wt% Mus showed highest power density of 586 mW cm(-2) at 150 degrees C without humidification, 24% higher than the pure PBI membrane (474 mW cm(-2)). Meanwhile, the PA doped composite membrane with 1 wt% Mus also displayed the highest mechanical strength (7.5 MPa) and lowest dimensional swelling (70.99% in area swelling and 202% in volume swelling). Compared with the pristine PBI membrane, the composite membranes had significantly improved durability under accelerated stress test (AST). The decreased ohmic resistance and increased polarization resistance after AST are related to the membrane thinning and the loss of catalyst active area, respectively. Most importantly, it was found that the strong interactions between Mus and PA molecules lead to improved acid retention ability of the composite membranes, thus less leached acid from the composite membrane reduces the negative effects on the catalyst degradation to alleviate degradation on cell performance and durability.