Effect of carbon fiber orientation in gas diffusion layers on performance of Polymer electrolyte membrane fuel cell

초록

To accelerate PEMFC commercialization, stable water management across various humidity conditions and a lightweight balance of plant (BOP) are essential, requiring structural optimization of the gas diffusion layer (GDL). This study investigates how GDL fiber orientations, Diagonal (45 degrees), Vertical (90 degrees), and Parallel (0 degrees), affect electrochemical performance at RH levels from 100% to 25%. Results reveal a fundamental shift in dominant physical mechanisms depending on RH. At RH 100%, Diagonal achieved the highest peak power density (790 mW/cm2), followed by Vertical (750) and Parallel (680), with drainage being the key factor. Conversely, at RH 25%, a performance inversion occurred between Parallel and Vertical. Parallel (220 mW/cm2) significantly outperformed Vertical (120) due to superior water retention and gas diffusion under dry conditions. Importantly, Diagonal maintained the highest performance across all levels, reaching 230 mW/cm2 at RH 25%. Furthermore, Diagonal and Parallel maintained strong performance retention of 29.1% and 32.4%, while Vertical's performance dropped to 16.0% due to severe membrane dehydration. Overall, the diagonal orientation offers an ideal balance by combining high-humidity drainage and low-humidity retention capabilities. These findings validate the diagonal structure as an essential design parameter for next-generation, humidifier-less fuel cells, ensuring operational stability in diverse environments.

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