The performance of Al-alloy bipolar plates for the PEMFC (proton exchange membrane fuel cell) system is investigated in this paper. The metallic bipolar plates are modified with a Ni–P coating. The performance of the Al-alloy bipolar plates is evaluated by the coating structure, corrosion resistance, contact angle and single cell performance. The results indicate that the coated aluminium bipolar plates demonstrate hydrophobic and anti-corrosive properties. The hydrophobic property increases the contact angle on the surface from 46.08° to 80.51°. Meanwhile, the corrosion rate of the Ni–P coating can be over 1 order of magnitude lower than that of the substrate. Hence, the substrate with the coating maintains superior performance under the long term test. The present study proves that both the hydrophobicity and corrosion resistance significantly affect the metallic bipolar plate.
In this paper, a fuel cell/lithium battery hybrid system for portable applications is developed, the system includes a polymer electrolyte membrane fuel cell stack, two hydrogen canisters, a lithium battery, a DC/DC converter cascaded to fuel cell and control electronic subsystem. The hardware circuit is designed for the system and the software program is written to realize the energy management of the hybrid power system, keeping the fuel cell in a good working condition under the precondition of satisfying the load power demand. The dynamic and static characteristics of the system are tested, and the tests show that the hybrid system allows the output of fuel cell to be buffered when handles sudden load changes. Energy management strategy can increase life span of the fuel cell because it avoids the counter-polarization of fuel cell during load mutation.
By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained.