Investigation of the Influence of Catalyst Layer and Carbon Structure for Cell Performance Using Reaction and Mass Transport Simulation of PEFC
Authors: Yamamoto Atsushi , Inoue Gen 
Published: December 2024

The expectation of hydrogen is growing towards achieving a carbon-neutral society. In particular, further popularization of Polymer Electrolyte Fuel Cell (PEFC) is desired not only for passenger vehicles but also heavy duty vehicles. Therefore, high performance, high durability and cost reduction of the catalyst layer (CL) are becoming increasingly important. In recent years, research on mesoporous carbon (MPC) has become active [1, 2]. MPC exhibits high catalytic activity because this carbon is able to avoid sulfonic acid poisoning by reducing contact between the ionomer and Pt surface. However, it is disadvantage from the perspective of mass transport as it is necessary to supply oxygen and protons to the inside of the carbon support. Many studies have been conducted to balance sulfonic acid inhibition and mass transport of oxygen and protons of MPC. But it is still unclear which factors of the carbon structure play an important role for the performance and durability. Currently, carbon selection is being carried out by trial and error, and it is essential to provide design guidelines for CL and carbon structures to improve performance and durability.

Our research group have developed a reaction and mass transport simulation within CL of PEFC and investigated the influence of CL structure for mass transport and cell performance [3, 4]. In this study, we have developed a model that takes into account the mass transport inside carbon support by extending the above CL scale model. Regarding the modeling of the internal carbon support, as reported in Chowdhury et al.'s research, the pore size distribution and surface wettability inside the carbon support are used to calculate the water uptake in the catalyst support, enabling the calculation of Electrochemical Surface Area (ECSA), proton conductivity, and gas diffusivity based on relative humidity (RH) [5]. By conducting such modeling, it became possible to simulate the polarization curve of CL using MPC. The calculated results, as reported in the studies by Ramaswamy [6] and Shinozaki [7], show that Pt utilization, proton conductivity, and gas diffusivity change depending on the RH inside the CL, and the polarization curve accurately match the experimental results.

Furthermore, using this model, we simulated the effects of different MPC structures for FC performance. The relationship between carbon structures such as the ratio of Pt supported within the carbon interior and surface and depth from the carbon surface and cell performance will be reported in this presentation.

Acknowledgements:

This work is supported by the Junichi Miyamoto Hydrogen Research Award.

References:

[1] M. Uchida et al., J. Power Sources, 315, 179 (2016)

[2] V. Yarlagadda et al., ACS Energy Lett., 3, 618 (2018).

[3] G. Inoue et al., J. Power Sources, 347, 108 (2017).

[4] G. Inoue et al., J. Power Sources, 374, 196 (2018).

[5] A. Chowdhury et al., J. Electrochemical Society, 170, 114525 (2023).

[6] N. Ramaswamy et al., J. Electrochemical Society, 167, 064515 (2020).

[7] K. Shinozaki et al., J. Electrochemical Society, 158 (5), B467 (2011).