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Reinforced gel-state polybenzimidazole hydrogen separators for alkaline water electrolysis
Energy & Environmental Science ( IF 32.5 ) Pub Date : 2022-09-16 , DOI: 10.1039/d2ee01922a
Muhammad Luthfi Akbar Trisno, Asridin Dayan, Su Ji Lee, Franz Egert, Martina Gerle, Mikkel Rykær Kraglund, Jens Oluf Jensen, David Aili, Aleksandra Roznowska, Artur Michalak, Hyun S. Park, Fatemeh Razmjooei, Syed-Asif Ansar, Dirk Henkensmeier

A new membrane fabrication process is presented, in which PBI is cast from a phosphoric acid-based solution and transformed into a KOH doped membrane by immersion in KOH solution. At room temperature, such membranes show a remarkably high conductivity of 300 mS cm−1 in 25 wt% KOH solution, 3 times higher than that of conventional PBI membranes cast from DMAc. While swelling of PBI in KOH solution is highly anisotropic, the phosphoric acid-cast membrane shrinks isotropically when immersed in KOH solution, indicating that the ordered, presumably lamellar structures, which are suspected to hinder transfer of ions through the membrane, are transferred into a gel-state. This is further supported by WAXS analysis. DFT calculations suggest that the broad signal in WAXS is related to the distance between hydrogen bonded imidazolides. The soft nature of the KOH doped PBI was mitigated by reinforcement with porous supports. By using a PTFE support, the tensile strength increased from 2 to 32 MPa, and the Young's modulus from 19 to 80 MPa. Immersion in 25 wt% KOH at 80 °C indicated high stability. In the electrolyzer, a conventional PBI membrane failed within 200 hours. In contrast to this, a PTFE-supported separator reached 1.8 A cm−2 at 1.8 V and was operated for 1000 hours without failure, which is the longest operation time for ion-solvating membranes to date.

中文翻译:

用于碱性水电解的增强型凝胶态聚苯并咪唑氢分离器

提出了一种新的膜制造工艺,其中 PBI 从磷酸溶液中浇铸而成,并通过浸入 KOH 溶液中转化为 KOH 掺杂膜。在室温下,这种膜显示出 300 mS cm -1的非常高的电导率在 25 wt% KOH 溶液中,比使用 DMAc 浇铸的传统 PBI 膜高 3 倍。虽然 PBI 在 KOH 溶液中的溶胀是高度各向异性的,但磷酸浇铸膜在浸入 KOH 溶液时会各向同性地收缩,这表明可能阻碍离子通过膜转移的有序的、可能是层状的结构被转移到一个凝胶状态。WAXS 分析进一步支持了这一点。DFT 计算表明 WAXS 中的宽信号与氢键咪唑啉之间的距离有关。KOH 掺杂的 PBI 的柔软特性通过多孔载体的增强得到缓解。通过使用 PTFE 支撑,拉伸强度从 2 MPa 增加到 32 MPa,杨氏模量从 19 增加到 80 MPa。在 80 °C 下浸入 25 wt% KOH 中表明稳定性高。在电解槽中,传统的 PBI 膜在 200 小时内失效。与此相反,PTFE 支撑的隔板达到 1.8 A cm-2在 1.8 V 下运行 1000 小时无故障,这是迄今为止离子溶剂膜最长的运行时间。
更新日期:2022-09-16
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