Abstract
Our study is to develop a coating with low resistivity and high corrosion resistance to protect the metallic substrate, which serves to replace the traditional graphite material to reduce the weight, volume and cost for direct methanol fuel cell (DMFC). The elemental composition of the electrolessly deposited Ni-P coating in this report has been determined to be Ni : 85-87 at.%, P : 13.5-14.9 at.% by EDX. And four-point probe results show the resistivity of the coatings to be around 54-95 μΩ-cm. In addition, various analytical methods were employed including, the surface morphology study by SEM, crystal structure by XRD and corrosion properties by potentiodynamic test. The results of potentiodynamic test reveal that Ni-P coating with higher P content and amorphous structure shows nobler corrosion potential than other materials in the simulated anode working environment (0.5M H2SO4 + 10vol % methanol solution). And the potentiostat test shows the negative corrosion current at all times (-0.1V vs. SCE), meaning the negative current provides “cathodic protection” in our system. After analyzing the electrolyte for 10 hrs by potentiostatic test, no metal ions were found in the solution. Besides, the real DMFC performance test shows excellent performance than commercial one (about 18% growth). Since, the electroless deposition method is more easily controlled and less expensive than the PVD or CVD processes, it has high potential as corrosion protection coating for DMFC bipolar plate.