In today's wave of energy transition, fuel cells, as an efficient and clean energy conversion technology, have attracted much attention. And the importance of membrane electrode (MEA) as the core component of fuel cell is self-evident. It is not only the place where the electrochemical reaction takes place, but also the key factor that determines the performance, lifetime and cost of the fuel cell. So what are the secrets of membrane electrode?

Structure and Composition of Membrane Electrodes

Membrane electrodes are mainly composed of proton exchange membrane, catalyst layer and gas diffusion layer. The proton exchange membrane is the core component of the membrane electrode, which not only conducts protons and isolates hydrogen and oxygen, but also provides support for the catalyst. Currently, perfluorosulfonic acid (PFAS) membranes have become the mainstream proton exchange membrane materials due to their excellent mechanical properties, thermal stability and chemical stability.

Working principle of membrane electrode

The working principle of membrane electrodes is based on electrochemical reactions. In a fuel cell, hydrogen undergoes an oxidation reaction on a catalyst layer at the anode to produce protons and electrons. The protons are transferred to the cathode through a proton exchange membrane, while the electrons flow through an external circuit to form an electric current. At the cathode, oxygen combines with the protons and electrons to form water. Throughout the process, the proton exchange membrane plays a key role in isolating and conducting the protons.

Membrane Electrode Preparation Technology

The preparation technology of membrane electrode has gone through the development process from disordered to organized. The first generation of gas diffusion electrode method (GDE) is to coat the catalyst on the gas diffusion layer, and then hot press it with the proton exchange membrane to form the membrane electrode. This method is simple and mature, but the catalyst utilization is low. The second generation Catalyst Coated Membrane (CCM) method is to coat the catalyst directly on the proton exchange membrane, and then hot press it with the gas diffusion layer to form a membrane.The CCM technology improves the catalyst utilization rate, and is the mainstream commercial preparation method at present. The third generation of ordered membrane electrodes, on the other hand, builds ordered structures inside, such as nano-array structures. These ordered structures are able to optimize the transport channels for protons, electrons, and matter, and reduce transport resistance, thus improving battery performance and lifetime.

Key Performance Indicators for Thin Film Electrodes

The preparation technology of membrane electrode has gone through a development process from disorder to order. The first generation of gas diffusion electrode (GDE) method is to coat the catalyst on the gas diffusion layer and then hot press it with the proton exchange membrane to form the membrane electrode. This method is simple and mature, but the catalyst utilization is low. The second generation Catalyst Coated Membrane (CCM) method is to coat the catalyst directly on the proton exchange membrane, and then hot press it with the gas diffusion layer to form a membrane.The CCM technology improves the catalyst utilization rate, and is the mainstream commercial preparation method. The third generation of ordered membrane electrodes, on the other hand, builds ordered structures inside, such as nano-array structures. These ordered structures are able to optimize the transport channels for protons, electrons, and matter, and reduce transport resistance, thus improving battery performance and lifetime.

Prospects for membrane electrodes

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Membrane Electrodes: The “Mysterious Power” of Energy Conversion