Materials, Flow-Field Geometry, and Operating Conditions in Low-Temperature PEM Fuel Cell Bipolar Plates: A Critical Review and Future Research Directions

Low-temperature proton exchange membrane fuel cells (LT-PEMFCs) constitute a key technology in the context of global energy decarbonization that combines high electrochemical efficiency, low operating temperatures (60–80 °C), and use in transportation, distributed generation, and portable applications. Bipolar plates (BPPs) are the backbone of a fuel cell. They carry out many functions, including electrical conduction, distribution of reactants, thermal management, and mechanical support. BPPs contribute approximately 60–80% to the total system weight and 30–45% to the total system cost. There are many research gaps in BPPs. Previous studies on BPPs are fragmented, and many studies focus on material and geometric design of flow fields, but research on how these factors affect the overall performance of the cell is absent. This segmentation limits the options for developing durable and scalable technological solutions. This review proposes a conceptual approach around three axes: (i) materials and surface engineering (graphite, coated metals, and polymer composites), (ii) flow-field geometry (serpentine, parallel, interdigitated, and bio-inspired), and (iii) operating conditions (temperature, humidity, pressure, stoichiometry, and dynamic regimes). A systematic review of literature published between 2015 and 2025 identified 315 eligible studies, which were retained for qualitative synthesis; from these, 160 representative references were selected for citation based on scientific relevance, methodological rigor, impact, and contribution to the MGOC framework, prioritizing mainly Q1–Q2 publications indexed in Scopus, Web of Science, and ScienceDirect and providing evidence for identifying and elaborating research gaps related to integrated design, multi-objective optimization, and predictive modeling.