Research Progress of Conductive and Corrosion-Resisntant Coatings for Metal Bipolar Plates

As one of the core components of fuel cell, bipolar plate has the important functions, namely, collecting the current generated by fuel cell, supplying reactive gas to the electrodes and preventing the penetration of reactive substances between the electrodes. Bipolar plate should possess excellent conductivity, high corrosion resistance, low cost, good mechanical properties and gas tightness. Compared with graphite bipolar plate, metal bipolar plate has better mechanical properties, easy processing and lower cost. However, metal bipolar plates are prone to corrosion in the acidic working environment of fuel cells, resulting in low output efficiency, which seriously affects the application of fuel cells. Therefore, surface anti-corrosion treatment is the key technology for fuel cells to achieve breakthrough in the application. It is always an important task to develop new coatings for bipolar plates with excellent electrical conductivity and corrosion resistance in this field. In this paper, the preparation, corrosion resistance and conductivity of several anti-corrosive coatings, including carbide coatings, nitride coatings, carbon-based coatings, graphene-based coatings, conducting polymer coatings and high entropy alloy coating, in recent years are systematically introduced. The key problems that still need to be solved in the practical application of metal bipolar plates are put forward, and the development trend of anti-corrosion coating for metal bipolar plates is also prospected.