A polymer electrolyte fuel cell (PEFC) is an apparatus that causes a fuel gas containing hydrogen and an oxidant gas containing oxygen, such as the air, to electrochemically react with each other, thereby simultaneously generating electric power and heat.
Basic components of the PEFC are shown in the cross-sectional view of FIG. 6. At first, there are an electrolyte membrane 15 that selectively transports hydrogen ions, and an anode electrode 22 and a cathode electrode 23 that are formed on the surfaces of the electrolyte membrane 15. These electrodes have an anode catalyst layer 16 and a cathode catalyst layer 17 that are formed on surfaces of the electrolyte membrane 15, as well as gas diffusion layers 18 (GDLs) that are placed on the external sides of the catalyst layers and that combine air permeability and electronic conductivity.
An assembly obtained by thus joining the electrolyte membrane 15, the anode electrode 22 and the cathode electrode 23 in a unified manner is called a membrane electrode assembly of an electrolyte membrane and electrodes (Membrane Electrode Assembly; MEA). Hereinafter, this is referred to as “MEA 10.”
Moreover, a frame 9 is put on the outer periphery of the MEA 10, thereby forming an assembly 14. A cross-sectional view of the outer peripheral portion is shown in FIG. 7. The frame 9 is put on the outer periphery of the MEA 10. Conductive separators 11 for fixing the MEA with the MEA mechanically placed therebetween and for electrically connecting adjacent MEAs 10 to each other in series are placed at both sides of the MEA 10. Gas flow channel grooves 13 for supplying a reaction gas to each electrode and for carrying generated water or surplus gases away are formed on portions of the separators 11 that are in contact with the MEA 10. The structure in which the MEA 10 is placed between the pair of separators 11 is called a single cell module, or simply cell 2.
Furthermore, in order to supply the reaction gas to the gas flow channel grooves 13, manifold holes are provided on the peripheral parts of separators 11, thereby distributing the reaction gas. Additionally, in order to prevent the reaction gas, etc. supplied to the gas flow channel grooves 13 from leaking to the outside or mixing, sealing members 20 (gaskets) are placed between the pair of separators 11 so that the sealing members 20 surround electrode-forming parts of the MEA 10, i.e., the outer periphery of the power generation region.
Here, precious metals such as platinum are used for electrodes of the MEA 10. When the MEA 10 is discarded, the MEA 10 is removed from the portion of frame 9, and precious metals included in the electrodes should be collected and recycled.
A method of disassembling a conventional assembly 14 of electrolyte is shown with reference to cross-sectional views of FIGS. 8A and 8B. As shown in FIG. 8A, there is a method in which a separation part 24 (shown by dashed lines) for splitting the frame 9 into two or more pieces is formed therein, and the frame 9 is separated from the separation part 24 serving as a starting point, to thereby remove the MEA 10 (for example, WO/2009/144940).
FIG. 9 is a diagram that shows a configuration of the conventional electrolyte assembly described in WO/2009/144940. In FIG. 9, a frame 105 is joined to the outer peripheral part of a MEA 101. Bolt holes 102 for fastening stacked single cells, manifold holes 103 for supplying gases, and gaskets 104 for sealing gases are placed on the frame 105, and a cutoff line 106 is formed around the inner peripheral part. By such a configuration, upon disassembling the electrolyte assembly, the inner peripheral part of the frame 105 is separated using the cutoff line 106, and the MEA 101 is removed therefrom.
USPTO Backgrounds
USPTO Backgrounds