Enhanced low-humidity performance of proton-exchange membrane fuel cell by introducing hydrophilic CNTs in membrane electrode assembly

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.