Abstract
Nickel foam has been applying as the electrode support material for alkaline direct ethanol fuel cells, since its unique three-dimensional network structure helps efficiently use the catalyst to improve the cell performance. In this work, the effect of the thickness of nickel foam electrodes on cell performance is investigated. The experimental results show that the nickel foam thickness influences both the electron conduction and mass transfer, and the optimal thickness is a trade-off between them. Through XRD, SEM image, polarization curve test, EIS test and CV test, it is found that the nickel foam electrode with the thickness of 0.6 mm has better performance than that of 0.3 mm and 1.0 mm. The thinner the nickel foam, the better the conductivity. However, the corresponding three-dimensional space becomes narrower, which leads to partial agglomeration of the catalyst and hindrance of mass transfer. In addition, the influence of catalyst loading on the performance of 0.6 mm nickel foam electrode is explored. The maximum power density of 1.0 mg cm−2 Pd loading reaches 56.3 mW cm−2 at 60 °C, which is higher than that of 2.0 mg cm−2 loading, indicating that the three-dimensional network structure of nickel foam can efficiently utilize the catalyst, and fully exert the catalytic function of the catalyst even at a lower catalyst loading. Moreover, the effects of operating temperature and ethanol concentration on cell performance are also studied. The cell performance increases with the increase of temperature, and it reaches the highest with 3 M ethanol.
The thickness of nickel foam influences both the electron conduction and mass transfer in 3D porous anode, and the optimal thickness is a trade-off between them. The 0.6 mm thickness nickel foam electrode with 1 mg cm−2 Pd loading reaches 56.3 mW cm−2 at 60 °C, which is higher than that of 2 mg cm−2 loading, proving the efficient utilization of catalyst. [Display omitted]
•3D porous structure of nickel foam enables efficient use of catalyst.•There is a trade-off in foam thickness between charge transfer and mass transfer.•0.6 mm foam electrode with 1 mg cm−2 Pd loading exhibits the power of 56 mW cm−2.