Proton exchange membrane (PEM) water electrolysers can produce high-purity, high-pressure green hydrogen. One of the most expensive components in a PEM electrolyser stack are the bipolar plates, whose function includes distributing water to the anode and maintaining electrical connectivity between cells. Bipolar plates are often manufactured from titanium due, in part, to its high resistance to corrosion in the acidic and oxidizing environment of the PEM electrolyser. Replacing titanium with cheaper materials could improve the cost competitiveness of PEM electrolysers. Now, Ulf-Peter Apfel and colleagues at Ruhr University Bochum and the Fraunhofer Institute for Environmental Safety and Energy Technology find that while cheaper carbon bipolar plates corrode quickly in typical ex situ accelerated aging tests, when applied in a real PEM electrolyser, they operate comparably to titanium components.

The researchers investigate bipolar plates made from a thermoplastic-bound carbon matrix. The team test them in an ex situ corrosion cell under various conditions thought to simulate typical electrolyser environments: temperatures of 40–80 °C; pH values between 0 and 4; and potential of 2 V versus RHE (reversible hydrogen electrode). The carbon bipolar plates display much higher corrosion current densities than those made from titanium — 170 times higher at pH 1 and 80 °C. However, when the researchers perform accelerated stress tests in a PEM electrolyser (which involves alternating current density between 1 and 3 A cm^–2), whether using carbon- or titanium-based bipolar plates, they observed stable operation for over 500 h. The unexpectedly high stability of the carbon-based bipolar plates under realistic conditions suggests that they warrant further investigation and that a reassessment of ex situ testing protocols is needed.

质子交换膜（PEM）水电解槽可以生产高纯度、高压绿色氢气。 PEM 电解槽中最昂贵的组件之一是双极板，其功能包括将水分配到阳极并维持电池之间的电连接。双极板通常由钛制成，部分原因是钛在 PEM 电解槽的酸性和氧化环境中具有高耐腐蚀性。用更便宜的材料代替钛可以提高 PEM 电解槽的成本竞争力。现在，波鸿鲁尔大学和弗劳恩霍夫环境安全与能源技术研究所的 Ulf-Peter Apfel 及其同事发现，虽然更便宜的碳双极板在典型的异位加速老化测试中腐蚀得很快，但当应用于真正的 PEM 电解槽时，它们的运行速度相当到钛部件。

研究人员研究了由热塑性粘合碳基质制成的双极板。该团队在模拟典型电解槽环境的各种条件下在异位腐蚀池中对它们进行了测试：温度 40–80 °C； pH值在0到4之间；以及 2 V 与 RHE（可逆氢电极）的电位。碳双极板的腐蚀电流密度比钛制成的双极板高得多，在 pH 1 和 80 °C 下高出 170 倍。然而，当研究人员在 PEM 电解槽（涉及 1 至 3 A cm ^–2之间的交流电流密度）中进行加速应力测试时，无论使用碳基还是钛基双极板，他们都观察到稳定运行超过 500 小时。碳基双极板在现实条件下出乎意料的高稳定性表明它们值得进一步研究，并且需要重新评估异位测试方案。