Thin Cation-Exchange Layers Enable High-Current-Density Bipolar Membrane Electrolyzers via Improved Water Transport
Thin Cation-Exchange Layers Enable High-Current-Density Bipolar Membrane Electrolyzers via Improved Water Transport
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DOI：
10.1021/acsenergylett.0c02078
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发表时间：
2021-01-08
影响因子：
22
通讯作者：
Boettcher, Shannon W.
中科院分区：
文献类型：
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作者：
Oener, Sebastian Z.;Twight, Liam P.;Boettcher, Shannon W.
使用合适的水解离（WD）催化剂，双极膜（BPM）可以在阴离子交换层和阳离子交换层（分别为AEL和CEL）之间的接合处有效地将水解离成H+和OH-。然而，首先，水必须通过AEL或CEL运输，因此逆着水合H+和OH-的向外流动。这是BPM架构固有的挑战，并且将操作限制到通常小于0.5的电流密度。A.cm在这里，我们探讨了水传输如何影响参考碱性和酸性膜电解槽的耐用性和性能，我们使用所获得的见解来设计具有改进水传输的BPM。我们展示了薄的CEL BPM（2 μ m的Nafion CEL垂直棒，类似于200 nm的TiO 2垂直棒，类似于200 nm的NiO+离聚物垂直棒50 μ m的Sustainion AEL），其在阳极和阴极之间保持了类似于14个单位的pH差，电流密度高达A.cm（-2），总的水电解电压类似于4 V，估计的WD过电位类似于1.5 V。这种高电流密度操作对于关键的新兴BPM应用至关重要，包括水和二氧化碳电解槽以及（再生）燃料电池。
With suitable water dissociation (WD) catalysts, bipolar membranes (BPMs) can efficiently dissociate water into H+ and OH- at the junction between anion- and cation-exchange layers (AEL and CEL, respectively). First, however, water must be transported through the AEL or CEL and thus against the outward flow of hydrated H+ and OH-. This is a challenge intrinsic to the BPM architecture and limits operation to current densities typically less than similar to 0.5 A.cm(-2). Here we explore how water transport affects durability and performance in reference alkaline and acidic membrane electrolyzers, and we use the insight gained to design BPMs with improved water transport. We demonstrate a thin-CEL BPM (2-mu m Nafion CEL vertical bar, similar to 200 nm TiO2 vertical bar, similar to 200 nm NiO+ ionomer vertical bar 50 mu m Sustainion AEL) which maintains a pH difference of , similar to 14 units between the anode and cathode for current densities of up to 3.4 A.cm(-2) with a total water electrolysis voltage of similar to 4 V and an estimated WD overpotential of similar to 1.5V. Such high-current-density operation is crucial for key emerging BPM applications, including in water and carbon-dioxide electrolyzers and in (regenerative) fuel cells.