8 terms related to hydrogen fuel cell membrane electrodes

MEA (Membrane Electrode Assembly), also known as membrane electrode, is the heart of the fuel cell. It consists of three parts: CCM (catalyst coating membrane) and cathode/anode diffusion layer. The diffusion layer plays the roles of water management, material distribution, and electron transfer. CCM is the main place for electrochemical reactions, involving issues such as the occurrence of reactions and the transfer and emission of products. From time to time, we see membrane electrode manufacturers releasing new technologies or products, which involve some professional terms. Let’s learn about them together in this article.

1. Pt loading (platinum loading)

The amount of precious metal platinum used per unit active area of the fuel cell membrane electrode, in mg/cm².

2. Membrane electrode series leaking rate (anode-to-cathode leaking rate)

The membrane electrode series leakage rate refers to the gas series leakage flow rate from the membrane electrode anode to the cathode per unit area under a certain pressure difference per unit time. The unit is l·min^-1·cm^-2.

3. Fuel cell reverse pole (cell reversal)

Fuel cell reverse pole refers to the phenomenon that when the fuel cell stack is running, due to insufficient hydrogen supply in the anode, the cell voltage of the cell is lower than zero volts. The performance of the anode catalyst is severely degraded, resulting in a degradation of the output performance.

Membrane electrode anti-reversal tolerance (cell reversal tolerance)

Membrane electrode anti-reverse polarity performance is used to evaluate the ability of the membrane electrode performance to maintain non-attenuation when reverse polarity phenomenon occurs in the fuel cell. It is generally characterized by the shutdown reverse pole running time and the lossless reverse pole running time, and the unit is minutes (min).

Duration of cell reversal until cell cutting off

The continuous operating time from the occurrence of pole reversal in the fuel cell until the fuel cell reaches the cut-off protection voltage and shuts down, the unit is minutes (min).

Duration of cell reversal without performance lose

The continuous reverse operation time from the occurrence of polarity reversal in the fuel cell until its rated power decreases within 4%, the unit is minutes (min).

4. Chemical stability of proton exchange membrane

The ability of the proton exchange membrane to withstand the strong oxidizing environment in the fuel cell is based on the operation of the membrane electrode from the start-up operation of the fuel cell to when the performance drops below the minimum acceptable safety performance, which is restricted by the decay of the chemical stability of the proton exchange membrane. Evaluated in terms of time, the unit is hours (hrs).

5. Durability of membrane electrode catalyst (durability of electrocatalyst)

The life of the membrane electrode catalyst during the operation of the fuel cell is evaluated by the operating time of the membrane electrode from the start of the fuel cell to the time when the performance drops below the minimum acceptable performance, which is restricted by the decay of the catalytic activity of the catalyst. The unit is hours (hrs) ).

6. Durability of catalyst support in MEA

The lifetime of the membrane electrode catalyst support (usually a carbon support) during fuel cell operation, which is limited by the corrosion of the catalyst support from the time the membrane electrode is started up and the performance drops below the minimum acceptable performance specified by the supplier. Run time is evaluated in hours (hrs).

7. Mechanical durability of proton exchange membrane in MEA

The life of the proton exchange membrane under different mechanical stresses is measured as the operating time of the membrane electrode from the start-up of the fuel cell until the performance drops below the minimum acceptable performance specified by the supplier, governed by the decay of the mechanical properties of the proton exchange membrane. Evaluation, unit is hours (hrs).

8. Accelerated stress test and evaluation

By operating under specific extreme working conditions, the fuel cell membrane electrode can complete the attenuation that may occur during the entire life cycle in a short period of time, thereby quickly testing the life or durability of the membrane electrode and performing performance evaluation.