TY - JOUR
T1 - Alternative architectures and materials for PEMFC gas diffusion layers
T2 - A review and outlook
AU - Lee, F. C.
AU - Ismail, M. S.
AU - Ingham, D. B.
AU - Hughes, K. J.
AU - Ma, L.
AU - Lyth, S. M.
AU - Pourkashanian, M.
N1 - Funding Information:
Similarly, Chen-Yang et al. [148] fabricated composites from Vulcan XC-72 and PTFE (0, 10 and 20 wt%). Again, all of the carbon black based substrate exhibited just half the power density of the commercial MPL coated ELAT® GDL (E-TEK). Since the electrical conductivity of carbon black is comparable to the carbon paper GDLs, the poor performance can be attributed to lower gas permeability. Conventional carbon paper has an abundance of macropores which facilitate high gas flux. However, carbon black composites are largely meso- and microporous, meaning that gaseous reactants must compete with the liquid water when diffusing through the pores, leading to mass transport losses. This limitation of the Vulcan XC-72 GDL is supported by the measured the air flux and the permeability of the carbon black GDL being significantly lower than the LT 1200 MPL coated carbon paper (9.77 × 10−12 and 218.6 × 10−12 respectively). Moreover, the PTFE content of these carbon black GDLs is quite high (up to 50%), this is likely to have reduced the porosity and blocked the pathways for reactant gases. Although Shim found that the power density increases up to 40% wt. PTFE, this is likely due to the reduction in flooding phenomena.Innovative work has been also undertaken by growing carbon nanotube directly on carbon paper substrates, via chemical vapour deposition [160, 167–170]. The aim of this is to increase the contact between the GDL and the electrocatalyst layer, and the formation of a hybrid catalyst/microporous, thus improving the diffusion characteristics, reducing charge transfer losses, and increase catalyst utilisation. For example, Sandström et al. [167] grew carbon nanotubes on an SGL 34 AA carbon paper using different temperatures and flow rates of C2H4. These were then doped with Pt particles and acted as a multifunctional layer. They reported a reduction in charge transfer resistance of 38% using this technique compared with Vulcan XC-72 as Pt support. Tang et al. [169] used the same methodology grow CNT on Toray TGPH 090, as a hybrid microporous/catalyst layer. Fig. 15 shows the (a) pristine carbon fibre and (b) the grown CNT. The maximum power density of 670 mW cm−2 was reached from the MEA with the in-situ grown CNT MPL compared to carbon black and commercial CNT, with a peak power density of 590 mW cm−2 and 365 mW cm−2 respectively. However, the durability of such fragile fibres in fuel cell conditions remains to be evaluated.The first author would also like to thank the ESPRC CDT for Clean Fossil Energy and Carbon Capture Storage (EP/L016362/1) as well as the International Flame Research Foundation for their financial support. The authors would like to acknowledge the support of the Royal Society (RS): The bilateral Royal Society (RS) – Japan Society for the Promotion of Science (JSPS) research grant (IEC\R3\170032).
Funding Information:
The first author would also like to thank the ESPRC CDT for Clean Fossil Energy and Carbon Capture Storage ( EP/L016362/1 ) as well as the International Flame Research Foundation for their financial support. The authors would like to acknowledge the support of the Royal Society (RS): The bilateral Royal Society (RS) – Japan Society for the Promotion of Science ( JSPS ) research grant ( IEC\R3\170032 ).
Publisher Copyright:
© 2022 The Authors
PY - 2022/9
Y1 - 2022/9
N2 - This paper reviews some of these new innovations in both the macroporous substrate and the microporous layer (MPL). A diverse range of macroporous substrates and designs is shown, encompassing various carbon-based and metal-based materials and innovative fabrication methodologies. A critical assessment of innovative MPL materials and designs for performance improvements is presented, taking into account pore size distribution and microstructure. An analysis of the effect of wettability and hydrophobic agents in the substrate and MPL is performed. One of the notable findings is that, among other key findings, significant performance enhancement is realised through employing graduated porosity and/or wettability GDLs. Finally, recommendations for future work into GDL materials and designs are made, with the aim of ultimately improving the overall cell efficiency.
AB - This paper reviews some of these new innovations in both the macroporous substrate and the microporous layer (MPL). A diverse range of macroporous substrates and designs is shown, encompassing various carbon-based and metal-based materials and innovative fabrication methodologies. A critical assessment of innovative MPL materials and designs for performance improvements is presented, taking into account pore size distribution and microstructure. An analysis of the effect of wettability and hydrophobic agents in the substrate and MPL is performed. One of the notable findings is that, among other key findings, significant performance enhancement is realised through employing graduated porosity and/or wettability GDLs. Finally, recommendations for future work into GDL materials and designs are made, with the aim of ultimately improving the overall cell efficiency.
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U2 - 10.1016/j.rser.2022.112640
DO - 10.1016/j.rser.2022.112640
M3 - Review article
AN - SCOPUS:85131667040
SN - 1364-0321
VL - 166
JO - Renewable and Sustainable Energy Reviews
JF - Renewable and Sustainable Energy Reviews
M1 - 112640
ER -
