Fuel cell device comprising a membrane electrode assembly

#This application claims the benefit of priority of Europe Patent Application No. 21207900.8 filed on Nov. 12, 2021, the contents of which are incorporated by reference as if fully set forth herein in their entirety.

#The present application relates to a fuel cell device having a stack arrangement configured with a membrane-electrode assembly having a difference in a first and a second gas diffusion layer.

#The invention is suitable to be integrated in the stack design of a compact fuel cell system, in particular a compact fuel cell for transportation applications having a proton exchange membrane (PEM-FC), or any other type of electrochemical device comprising a stack of cells each including a membrane-electrode assembly to be alternatingly stacked between bipolar plates and accommodating channels or other kinds of pathways for conducting fluids for electrochemical reaction in the cells.

#Further objectives, advantages, features and applications of the present invention arise from the following description of the exemplary embodiments with reference to the drawings. In the drawing:

#FIG. 1A shows a schematic view on an upper side of a membrane-electrode assembly supported in a frame member according to a first embodiment of the present invention;

#FIG. 1B shows a schematic view on a lower side of the membrane-electrode assembly according to the embodiment of first the present invention;

#FIGS. 1A and 1B show an upper side and a lower side of a cell comprising a membrane-electrode assembly 20 framed by a frame member 10, wherein the shape and the perspective on the frame member 10 also represent an overall cross-section of a stack arrangement which is perpendicular to a stacking direction in a fuel cell device 100. Certain regions marked by dashed lines define for the whole stack arrangement a centrally arranged active region 120 and two transition regions 130 diametrically arranged on opposite sides of the active region 120. The active region accommodates the cells, or more particularly is occupied by a membrane-electrode assembly (MEA) including all electrochemically active elements of the cells. The transition regions 130 accommodate fluid pathways having a flat shaped flow cross-section for fitting into or between the stacked elements, particularly bipolar plates 30. Furthermore the transition regions 130 constitute a fluid interface enclosing internal pathways forming a fluid communication between the cells and outer arranged ports 110 being part of an internal manifold or other structures for a supply of air and a hydrogen based fuel gas or for a discharge of exhaust gas and water. One port 110 per side of a cell may also deliver and return a coolant for cooling the cell, however such port is not in fluid communication with the cell 20 via internal pathways enclosed with in one of the transition regions 130.

#The frame member 10 illustrated in FIG. 1A and FIG. 1B, comprise basically the same outer contours shared with bipolar plates 30 and is mostly formed flat with planar interface surfaces to be stacked properly when facing each other with two facing bipolar plates, as to be seen in FIG. 3. The frame member 10 serves for mechanical supporting and mounting the electrochemically active membrane-electrode assembly 20 in the stack arrangement.

#Within the transition regions 130 of the stack arrangement marked by dashed lines on the bipolar plate in FIG. 3, the bipolar plates 30 provide dedicated plate features 32 and fluid pathways 31 recessed therebetween in a surface of the bipolar plates 30. The plate features 32 and fluid pathways 31 have distinctive shapes for promoting, in a flat flow cross-section, a flow distribution of a fluid to be supplied or discharged throughout a transverse dimension of the membrane-electrode assembly 20 while achieving a preferable even pressure distribution across said flat flow cross-section. Such distinctive shapes for promoting a diffusion of fluid pressure might represent an array of round pillars form arranged in equal distances. However, alternative embodiments might provide another suitable design of plate features 32 for effecting the desired flow dynamics including, for example, plate features 32 in the form of channel walls for a splitting-up channel arrangement or the like.