Eight Terms Related to Hydrogen Fuel Cell Membrane Electrode Assembly

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

1. Pt loading

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

2. Membrane anode-to-cathode leaking rate

The membrane electrode cross leakage rate refers to the cross leakage flow rate of gas from the anode of the membrane electrode per unit area to the cathode per unit time under a certain pressure difference, in units of l•min-1•cm-2.

3. Cell reversal

Cell reversal refers to the phenomenon that the voltage of a cell is lower than zero volts due to insufficient hydrogen supply at the anode during the operation of the fuel cell stack, and the anode catalyst performance is severely attenuated, resulting in output performance attenuation.

① Cell reversal tolerance

The membrane electrode reversal tolerance is used to evaluate the ability of the membrane electrode performance to remain unchanged when the fuel cell reversal phenomenon occurs. It is generally characterized by shutdown reversal operation time and lossless reversal operation time, in minutes (min).

② Duration of cell reversal until cell cutting off

The continuous operation time from the occurrence of reversal phenomenon in the fuel cell to the shutdown of the fuel cell when the fuel cell reaches the cut-off protection voltage, in minutes (min).

③ Duration of cell reversal without performance lose

The continuous reversal operation time from the occurrence of reversal phenomenon in the fuel cell to the attenuation of its rated power by less than 4%, in 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 evaluated by the operating time of the membrane electrode from the start-up of the fuel cell to the time when the performance drops below the minimum acceptable safety performance, which is constrained by the attenuation of the chemical stability of the proton exchange membrane. The unit is hours (hrs).

5. Durability of membrane electrode catalyst

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-up of the fuel cell to the time when the performance drops below the minimum acceptable performance, which is constrained by the attenuation of the catalytic activity of the catalyst. The unit is hours (hrs).

6. Durability of catalyst support in MEA

The life of the membrane electrode catalyst support (usually a carbon support) during the operation of the fuel cell is evaluated by the operating time of the membrane electrode from the start-up of the fuel cell to the time when the performance drops below the minimum acceptable performance specified by the supplier, which is constrained by the corrosion of the catalyst support. The unit is hours (hrs).

7. Mechanical durability of proton exchange membrane in MEA

The life of the proton exchange membrane under different mechanical stresses is evaluated by the operating time of the membrane electrode from the start of the fuel cell operation to the performance falling below the minimum acceptable performance specified by the supplier, which is restricted by the attenuation of the mechanical properties of the proton exchange membrane. The unit is hours (hrs).

8. Accelerated stress test and evaluation

By operating under specific extreme conditions, the fuel cell membrane electrode completes the attenuation that may occur during the entire life cycle in a short period of time, and then quickly tests the life or durability of the membrane electrode and conducts performance evaluation.