Corrosion characteristics and fuel cell performance of a cost‐effective high Mn–Low Ni austenitic stainless steel as an alternative to SS 316L bipolar plate

Abstract

Summary In this study, newly developed high manganese (Mn) and low nickel (Ni) austenitic stainless steels were investigated as an alternative to conventionally used SS 316L for bipolar plate applications in proton exchange membrane fuel cells. Systematic studies on the corrosion behavior were carried out in simulated hydrogen and oxygen environments, for both half‐ and fuel‐cell conditions. The Mn‐based SS revealed nobler corrosion potential and comparable passive current densities to that of SS 316L. The passive current density of Mn‐based SS is well within the DoE 2020 target of <1 μA cm−2. Though MnSS1 steel has lean Ni content, the addition of Mn and N is beneficial for improving the corrosion performance, which is comparable to SS 316L. The recorded ICR values for Mn SS1 and SS 316L are 234.6 ± 20 and 155 ± 20 mΩ cm2 at a compaction force of 140 N cm−2, respectively. Both the steels do not to meet the DoE ICR target of 10 mΩ cm2, which requires conductive coating or improvement in oxide conductivity. The performances of the steels (both Mn‐SS and 316L SS) with varying thickness were also investigated in a single fuel cell condition with serpentine flow field design as bipolar plates with varying thickness (10, 5 and 2 mm). A maximum power density of 370 mW cm−2 was achieved with the Mn‐based metallic bipolar plates, whereas SS 316L showed 354 mW cm−2. By changing the composition of austenitic stainless steel, that is, using Mn SS1 instead of SS 316L the overall fuel cell cost decreases by three times.

A review of bipolar plates materials and graphene coating degradation mechanism in proton exchange membrane fuel cell

“…The potentiostat tests additionally showed that there is less corrosion in a simulated anode environment and were credited to the decrease in the H+ particles bringing about a negative current that provided cathodic protection to the 316L stainless steel. Recently, Kumar et al 20 studied the behaviors of two grades of stainless steel for BPP application. The magnesium-based stainless steel displayed more passive current density and better corrosion potential compared to nickel-based stainless steel.…”

“…3,18,19 The corrosion resistance of the BPP also can be enhanced utilizing the electrochemical properties of graphene in coating the substrate material and has been investigated by authors. 18,20 Pu et al 18 deposited graphene on the BPP substrate to improve the performance through the provision of the anticorrosion graphene coating for the PEMFC environment. Chung et al 21 developed a graphene layer on a nickel/stainless steel surface, and during this interaction, the carbon molecules at first formed round carbon structures on the nickel grain boundaries.…”

Corrosion and Materials Degradation in Electrochemical Energy Storage and Conversion Devices

“…The passive current density of the modified steel was < 1 μA/cm 2 ; however, the ICR values of both Mn SS (~234.6 mΩ cm 2 ) and 316 L SS (155 mΩ cm 2 at 1.4 MPa) do not satisfy the DoE limit, emphasizing the need of a conductive coating or oxide conductivity enhancement. [40] These works indicate that even though the SS is comparatively safer at normal operating conditions of PEMC, extreme conditions, such as high temperature and potential, could lead to corrosion, necessitating a proper conducting surface coating for long-term durability as discussed in the Section 2.1.1.1.…”

A High Conductive Composite Bipolar Plate with Conductive Network Constructed by Chemical Vapor Deposition

“…The proton exchange membrane fuel cell (PEMFC) is considered to be one of the most prized potential energy conversion devices in the 21st century due to its unique advantages, such as its high rate of energy conversion, pollution-free emissions, and noisefree operation [1][2][3]; however, owing to the high preparation cost of PEMFCs, its application is limited [4]. Bipolar plates (BPs) are key components of PEMFCs, and they are responsible for energy conduction, material transportation, structural support, etc.…”