Abstract
Hydrophilic carbon nanotubes (HCNTs) were introduced into the membrane electrode assembly (MEA) to improve its low-humidity performance. The effects of types, placement, loading, and relative humidity on the MEA performance were investigated. It has been found that the MEA with 20 wt% HCNTs loading both in anode and cathode achieved the best self-humidifying performance. Its current density reached 1550 mA cm−2 at 0.6 V, with a maximum power density of 953 mW/cm2 at 70 °C, 30 psi and 30% relative humidity conditions. Besides, the stability test shows that its current density at 0.6 V only decreased by 6.4% after 44 h performance test, while the performance of blank MEA without HCNTs decreased by 45% within 6 h testing period. This extraordinary performance under low humidity condition is ascribed to that the HCNTs contained in the MEA improve the water management and mass transportation by functioning as a dispersant and hydrophilic agent.
The MEA prepared by introducing hydrophilic CNTs (HCNTs) in both anode and cathode CL and MPL of GDL exhibits excellent self-humidification performance at cell temperature of 70 °C and 30% RH, the current density can be enhanced by 300% at 0.7 V and 41% at 0.6 V, respectively, and the maximum power density can be increased by 37%. After 44 h continuous running, the current density degradation is only 6.4% at 0.6 V, which is much better than that of the blank MEA. [Display omitted]
•The power density of MEA can be enhanced by the addition of hydrophilic CNTs.•Adding HCNTs in both catalyst layers and GDL simultaneously exhibits best results.•The current density can be enhanced by 300% and 41% at 0.7 V and 0.6 V.•The long term testing of 44 h reveals the good stability of the MEA at low RH.