Electrode for fuel cell comprising non-platinum catalyst and graphene layered structure, and membrane-electrode assembly comprising same
Applicant: KOLON INC [KR] / WO 2023018126 A1
This patent application from Kolon refers to a non-platinum catalyst system from a PEM fuel cell. The electrode for a fuel cell of the present invention has a structure in which a catalyst layer and a graphene layer are stacked and alternately laminated, and the conductive polymer is intended to improve the catalyst efficiency by limiting the transition metal particle size.
The catalyst is prepared by mixing CNT as a carbon support, iron(III) phthalocyanine chloride as an Fe—N precursor (M—N precursor) in a mass ratio of 1:2. Then, dispersing in aniline a mass ratio of 2:1 using distilled water as a solvent, and drying at 60° C/8 h to obtain a solid powder. Then heat-treating at 800 ° C/3 h under N2. Then dispersing with Nafion PFSA ionomer, distilled water, and normal-propyl alcohol and spray drying with a graphene dispersion in the first nozzle and the catalyst dispersion in the second nozzle. The graphene layers is sprayed first onto a release material of FEP (Fluorinated Ethylene Propylene) to form a graphene layer, then the catalyst layer is sprayed onto the graphene layer. This process is continued until there are 100 layers. The spray drying is carried out with a mist size of 10 μm at an ultrasonic frequency of 180 kHz. The syringe pump flow rate was set at ~1 ml/min, a nozzle moving speed of 10 m/s, and an air pressure of 4 L/min.
A membrane-electrode assembly (MEA) was then prepared by applying the formed electrode layer as a cathode electrode part and a Pt/C electrocatalyst as an anode electrode part by thermally compressing the polymer electrolyte membrane (PEM).
Performance evaluation was performed under the conditions of a temperature of 65° C., air pressure of 100 kPa, RH of 100%, and a H2/air flow rate ratio of 1.5/2.0. The performance improved when the Fe-N precursor was changed to a Co-N precursor (Example 2) and even further when a Mn-N precursor (Example 3) was employed.
This work is of high importance because the use of scarce platinum group metals (PGM) raises the cost and potentially reduces the overall deployment possible of PEM fuel cells (and PEM electrolysers). The use of a dual spray nozzle simplifies the production method. It is interesting that Manganese (Mn) performed best because although the demand for high purity Mn including for lithium-ion batteries is increasing, the metal still has lower criticality than either Pt or Co.
