Comprehensive analysis of PTFE distribution in gas diffusion layers using advanced ex-situ and in-situ characterization techniques
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Materials engineering (MPAEM), MSc
Publicerad
2024
Författare
RAVI SANKAR, SIVA BALAGANESH
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The performance and longevity of Proton Exchange Membrane Fuel Cells (PEMFCs)
are critically dependent on the properties of the gas diffusion layer (GDL).
This study investigates the hydrophobic treatment using the dip coating method
on two types of GDLs, namely dry-laid and wet-laid, using polytetrafluoroethylene
(PTFE) at target concentrations of 5 wt%, 20 wt%, and 50 wt%. The distribution
of PTFE across the thickness and surface of the GDLs is characterized to
understand its impact on water management and gas transport properties. The effectiveness
of the hydrophobic treatment is evaluated both ex-situ via contact angle
measurements and in-situ by limiting the current density to assess oxygen transport
resistance. Additionally, advanced characterization techniques, including Scanning
Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Raman
Spectroscopy, are employed to provide a detailed analysis of PTFE distribution,
correlating these findings with the GDL’s performance in operating PEMFCs.
**Key findings** reveal that while increased PTFE concentration improved hydrophobicity
and water management, excessive PTFE loading led to pore blockage,
negatively impacting oxygen transport resistance. The wet-laid GDL demonstrated
more uniform PTFE distribution and higher transport resistance compared to the
dry-laid GDL. These insights emphasize the importance of balancing PTFE concentration
to optimize both water management and gas diffusion in PEMFCs.
Beskrivning
Ämne/nyckelord
Gas diffusion layer , Proton exchange membrane fuel cell , PTFE , Dipcoating method , Limiting current Density