Development of a Two‐Stage Cold Pressing and Tempering Process of Graphite Compound Bipolar Plates

ABSTRACT Proton‐exchange membrane fuel cells (PEMFCs) are considered a key technology for decarbonized energy systems, particularly in combination with sustainably sourced green hydrogen. The functional performance and reliability of core components, such as bipolar plates (BPPs), depends critically on the manufacturing processes. This study explores a two‐stage isothermal manufacturing approach for graphite compound BPPs, combining low‐temperature compaction with a subsequent tempering step to replace conventional compression molding (hot pressing), enabling improved energy efficiency and production throughput. In order to qualify this process chain for further industrialization, PEMFC‐relevant component characteristics such as a low hydrogen permeability and a high electrical conductivity are key requirements. A D‐optimal experimental plan was applied to systematically assess influences such as pressing pressure, temperature, and as well as process times on 50 mm × 80 mm demonstrator plates. Subsequently, the demonstrators were characterized for the achievable hydrogen permeation and electrical conductivity, proving a suitability of the process chain within defined parameter sets. The approach demonstrates advantages in terms of reduced energy consumption and cycle times, offering a scalable alternative to conventional hot pressing for the production of thin, highly filled graphite‐polymer BPPs.