Characterisation of Nanocarbon‐Based Gas Diffusion Media by Electrochemical Impedance Spectroscopy

Abstract

A multi‐wall carbon nanotubes (MWCNTs)‐based gas diffusion medium (GDM) was prepared, where carbon black was partially substituted by carbon nanotube (CNT) in the formulation of the micro‐porous layer (MPL). A rheological analysis of the ink used to coat the gas diffusion layer (GDL) was previously performed to correlate viscosities with the slurry composition. Shear thinning inks with viscosity of 0.4 (Pa s–1) were obtained for a composition containing 10 wt.‐% of CNT and 12 wt.‐% of fluorinated polymer. Using the doctor‐blade technique, a coating thickness of about 100–150 μm was obtained.Moreover, electrochemical performance of a single cell assembled with the CNT‐based GDM was compared with that obtained with a sample without CNTs. In order to better understand the role of CNTs, electrochemical impedance spectroscopy (EIS) of the running fuel cell (FC) was also performed. As a result, it was found that the addition of CNTs sensibly improves single cell performances.

Preparation, ex situ and in situ Characterization of Gas Diffusion Media Containing and Non‐Containing Carboxymethylcellulose for PEM Fuel Cells

“…At high humidity this behaviour is more evident, due to more pronounced mass transfer limitations. Indeed, the polarization resistance keeps constant or decreases somewhat at low current densities and this is usually ascribed to the lowering of the anode charge transfer resistance [38,40]; thus the increase of the sum Rp+Rd can be ascribed to diffusion resistance, which is more dramatic for CMC-containing MPLs due to hydrophilic feature of CMC. These trends can also explain the voltage drop observed in Figure 4 and Figure 5 at high cathodic RH, above all for CMC-PTFE12.…”

Development of an optimal gas diffusion medium for polymer electrolyte membrane fuel cells and assessment of its degradation mechanisms

“…On the basis of a previous work [50], carbon nanotubes (CNTs, Nanothinx NTX1, purity: 97%, diameter: 10e30 nm, length: 10 mm, metal particles: 3 wt %), partially replacing carbon black powder, were used in order to make final coatings more conductive than the standard one. Moreover, inks containing a hydrophobic agent other than PTFE (i.e.…”

Effect of microporous layer composed of carbon nanotube and acetylene black on polymer electrolyte membrane fuel cell performance

“…A novel type of GDL prepared by growing carbon nanotubes directly on the fiber surface of carbon cloth was proposed in the work [4]. Stampino et al [5] fabricated a multi-wall CNTsbased MPL in which carbon black in the formulation of MPL was partially substituted by CNT. They assembled a single cell with the CNT-based MPL and found that its electrochemical performance was better than that obtained with a conventional MPL made by Vulcan XC-72R carbon black without any addition of CNT.…”