Research Progress of Thermal Diffusion Technology in Surface Modification of Metallic Bipolar Plate
Fuel cells have attracted much attention in recent years due to their environmental protection and high resource utilization advantages,which are of great significance to improving the global environment. Bipolar plate is an important part of fuel cells,which isolates oxidants and reducing agents in fuel cells. Electrons generated by the anode have been collected and then conducted to the cathode. They have good electrical conductivity and thermal conductivity;requiring low contact resistance and high corrosion resistance. Therefore,the Department of Energy (DOE) has established relevant performance indicators,which stipulate that bipolar plates can only be used in proton exchange membrane fuel cells when they meet the standards. At present,most of the bipolar plates in fuel cells are graphite bipolar plates,which have large thickness,high processing cost and poor flexibility,while metal bipolar plates are the best material to replace graphite bipolar plates,which are easy to process and low in cost. But in the acidic environment in which fuel cells operate,metal bipolar plates are prone to corrosion,resulting in a reduction in the output efficiency of fuel cells,which seriously affects the application. At present,the preparation of coatings on the surface of metal bipolar plates is the most widely studied. However,most of the coating methods are too complex,easy to form defects,and are too expensive for the commercialization of fuel cells. Therefore,the method of thermal diffusion modification of metal bipolar plates can be used to meet their service performance. This paper introduced different kinds of metal bipolar plates and different surface modification techniques of metal bipolar plates. Different kinds of thermal expansion modification techniques were listed,with a focus on the thermal expansion process,corrosion resistance and conductivity. The analysis results show that for the thermal expansion process,appropriate temperature should be selected when preparing the bipolar plate to reduce or eliminate the influence of deformation on the bipolar plate. The preparation of a uniform,dense and single thermal expansion layer could significantly improve the performance of metal bipolar plates. The oxidation film and passivation film formed in the air and simulated fuel cell solution environment also played an important role in the performance of metal bipolar plates. The research on the surface modification of metal bipolar plates by thermal expansion to improve its corrosion resistance,conductivity and service stability,and to develop a new composite process,is crucial to promote the application of metal bipolar plates in fuel cells. In addition,it is necessary to carry out more extensive performance tests of thermal diffusion modified metal bipolar plates to meet the requirements of fuel cells in terms of air tightness,flexural strength,density and compactness. It is also necessary to carry out long-term service performance research on thermal diffusion modified metal bipolar plates,and carry out long-term corrosion tests;conduct research on the development of new thermal diffusion and infiltration composite modification technology;develop thermal diffusion and infiltration modification equipment suitable for large-scale and industrial production to reduce production costs;and formulate a unified performance test standard for thermal diffusion modified metal bipolar plates.
万方数据
维普
