Membrane/ionomer degradation in proton exchange membrane (PEM) fuel cells caused by Fenton-reaction of Fe and Cu species with hydrogen peroxide is not unlike the development of Alzheimer’s in the human body. Stainless-steel dissolution under fuel cell-relevant conditions takes place via passive-transpassive-passive transitions (Figure 1) [1]. Moreover, rapid load cycling and concomitant global hydrogen starvation during the New European Driving Cycle (NEDC) [2] are very likely to create such transitions. In their presence, metal-stained carbon-coated bipolar plates lead to significant contamination of the MEA with Fe and Ni. In contrast, the mitigation of global fuel starvation in the NEDC makes it possible for the same plates to exhibit trace-metal contamination of the MEA as low as a pure graphite current collector. However, during both runs the carbon coating ensures a constant and low contact resistance between bipolar plates and gas diffusion layers (GLDs). To take the Alzheimer’s analogy a step further, these experiments show that the way the fuel cell is run can be more important than the quality of the components. In other words, lifestyle might beat genetics.At SMT we strongly believe in the power of carbon for electrochemical energy conversion due to its sustainability, low cost, high stability, high conductivity, and the absence of oxide film formation, thus, maintaining low contact resistance. We, therefore, offer (non-metal stained) carbon-precoated stainless steel for bipolar plates produced in a roll-to-roll fashion. Figure 1 . Transient dissolution behavior of a typical stainless steel, e.g., 304L, 316L, 904L, considered are only Fe and Cr species for simplification. In a potential step from OCP (+0.7 V vs. RHE), where Fe and Cr species are insoluble, to ±0 V vs. RHE, where the Fe species is soluble, Fe is preferentially leached (red trace in the transpassive part) until an all-Cr passive film has been reestablished, which takes about 100 s. The red and blue traces correspond to the Fe and Cr signal of an ICP-AES coupled to a flow cell with a stainless steel sample [1].[1] Li X, Zhou P, Ogle K, Proch S, Paliwal M, Jansson A, et al. Transient stainless-steel dissolution and its consequences on ex-situ bipolar plate testing procedures. Int J Hydrogen Energy. 2020;45:984-95.[2] Tsotridis G, Pilenga A, De Marco G, Malkow T. EU Harmonised Test Protocols for PEMFC MEA Testing in Single Cell Configuration for Automotive Applications. Petten (The Netherlands): EU; 2015. Figure 1
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