Fuel cell stack performance recovery method and system

Abstract

The invention discloses a fuel cell stack performance recovery method and system. The method comprises the following steps: setting fuel cell stack cathode air internal circulation supply, and detecting the voltage of a single cell output by a fuel cell stack; when the fuel cell stack is in a performance recovery working condition, starting internal circulation supply of cathode air of the fuel cell stack, and when it is detected that the voltage of a single cell is lower than a first threshold voltage, switching the fuel cell stack to a normal operation working condition; and when the fuel cell stack is in a normal operation condition, stopping internal circulation supply of cathode air of the fuel cell stack, and when it is detected that the voltage of the single cell is higher than a second threshold voltage, switching the fuel cell stack to a performance recovery condition. According to the invention, the performance of the fuel cell stack is rapidly and efficiently recovered, and the problems of reverse pole and irreversible attenuation of a single fuel cell or a local area are avoided.

Description

technical field [0001] The invention relates to the field of fuel cells, in particular to a fuel cell stack performance recovery method and system. Background technique [0002] At present, the commercial Pt / C catalyst is the main membrane electrode catalyst for proton exchange membrane fuel cells. When the fuel cell is parked for a long time or operated at low power, the surface of the catalyst is easy to form an oxide film on the surface of the metal Pt, resulting in a decrease in the catalytic activity of the catalyst. , resulting in attenuation of the output performance of the fuel cell stack. The existing fuel cell operation control strategy adopts the method of reducing or stopping the oxidant supply of the fuel cell during the operation of the current cell stack, increasing the overpotential of the negative electrode of the cathode, and reducing the output voltage of the fuel cell, which can reduce the oxide coating layer on the surface of the catalyst and achieve the...

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Problems solved by technology

[0003] However, due to the performance differences of single cells in the fuel cell stack, including the difference in the hydrogen gas permeability of the proton membrane of the single cell, the difference in the catalytic activity of the membrane electrode, the difference in the air atmosphere environment between the middle position and the two sides of the single cell cell, and the difference of the single cell The internal liquid water content is different. Therefore, when the oxidant supply is reduced or stopped when the fuel cell is running, the output voltage of one or more nodes will drop rapidly, the difference in oxygen deficiency in different reaction areas of a single cell will cause unbalanced reactions, or a single cell will appear. Partial water blockage of the membrane electrode, etc., may cause reverse polarity in a single battery or in a local location

At the same time, when the fuel cell stack restores the supply of oxidant, there is still a certain time difference from the supply of oxidant to the filling of the entire cathode cavity of the fuel cell stack. Polarity reversed in battery or local location

The reverse polarity of a fuel cell single cell will cause irreversible decay of the electrode catalyst carrier

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