A welding method for metal bipolar plates of fuel cells

Abstract

The invention provides a welding method of a metal bipolar plate of a fuel cell. The method comprises the following steps that an anode plate and a cathode plate in the metal bipolar plate are positioned, and the anode plate and the cathode plate are attached tightly; and then a laser beam is used for carrying out relative movement with the metal plate along the welding track of the metal bipolarplate so as to complete welding paths of a plurality of steps, so that the anode plate and the cathode plate are fused and connected, wherein the laser beam is a low-power high-frequency pulse laser beam; and the laser beam also has a welding initial buffer path before implementing the welding path, and also has a welding termination buffer path after the welding path is completed. According to the welding method, the air tightness of the bipolar plate is fully guaranteed, the welding percent of pass is 100%, the defect that air leakage of the metal bipolar plates caused by sealing in other mode is completely overcome, the industrialization and the automatic production of the metal bipolar plate electric pile is accelerated.

Description

technical field [0001] The invention relates to the technical field of fuel cells, in particular to a welding method for metal bipolar plates of fuel cells. Background technique [0002] A fuel cell is a power generating device that converts chemical energy in fuel and oxidant directly into electrical energy. Because it is an electrochemical reaction, without combustion, and not limited by the "Carnot cycle", the energy conversion efficiency is much higher than that of ordinary heat engines. In addition, fuel cells also have the advantages of no pollution, low noise, and high reliability, and have very broad market prospects in the fields of transportation, distributed power generation, and portable power generation. [0003] The bipolar plate is an important part of the fuel cell stack. The bipolar plate is used to distribute the reactants, conduct electricity, heat conduction and support the membrane electrode (MEA), and provide flow channels for the removal of the water ...

AI Technical Summary

Problems solved by technology

For a usable fuel cell, each bipolar plate must be qualified. If the pass rate cannot be guaranteed to be 100% during the bipolar plate sealing process, then each bipolar plate must be tested for leaks, which consumes a lot of manpower and material resources. and financial resources, at the same time, the leak detection test itself also has the risk of causing deformation or even damage to the bipolar plate, so the pass rate of the bipolar plate directly affects the cost and production capacity of the fuel cell

Common bipolar plate sealing methods include bonding and laser welding; bonding is mainly suitable for graphite bipolar plates, but the scrap rate is still high, and the glue used for bonding is prone to aging at the operating temperature of the fuel cell, resulting in leakage of the coolant. leak

The use of conventional high-power laser welding of metal bipolar plates can easily lead to breakdown of the bipolar plates and poor continuity of the welding line, resulting in air leakage and large deformation of the bipolar plates, which can reduce the contact area between the bipolar plate and the membrane electrode and increase the contact resistance. Affect the performance of the fuel cell, in severe cases, it cannot be used at all

[0004] In summary, for fuel cells, the sealing of the bipolar plate and its qualification rate are very important, which directly affect the investment time cost, economic cost and the performance and life of the fuel cell; for metal plates with a thickness of less than 0.15mm Welding is more difficult

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