Electrochemical cell stack with frame elements

Abstract

A redox fuel cell stack (1) comprises a plurality of essentially similar half-cell frames (2,3) of moulded polymer. Interleaved between them are semi -permeable membranes (4) and bipolar plate electrodes. The frames (2, 3) are rectangular, with margins (11) around central voids (12). At the voids, they have rebates (14) in abutting faces (15) for locating the plate electrodes. At their corners, they have apertures (17) for forming ducts throughout the stack for flow of electrolyte to and from the cell cavities provided by the voids (12). The frames (2) have electrolyte flow passages (18) open in their faces 15 abutting the frames 3 and leading towards each other. The passages stop short of each other and are surrounded by grooves containing sealing O-rings (20). Diagonally opposite ones of the passages (18) end at openings (22) passing through the frames (2). The other passages have no openings in the frames (2), but the frames (3) have openings through them in register with the ends of the passages. On the other side of the frames (2) and (3), the openings (21, 22) open into short passages (23) directed towards the central voids and debouching into electrolyte distribution rebates (24). Thus electrolyte can flow from one duct aperture (17) in one corner, via the passage (18) from the aperture, either through the frame (2) via the opening (21) or the frame (3) via the opening (22), through short passage (23) and the respective distribution rebate and into the central void to whichever side of the plate electrode it was directed by the opening (21, 22). From the opposite end of the central void, the electrolyte is lead back into the diagonally opposite duct aperture.

Description

technical field [0001] The present invention relates to an electrochemical or electrolytic cell stack and particularly, but not exclusively, to a regenerative reduction / oxidation (redox) fuel cell stack. Background technique [0002] Known electrochemical cells generally comprise from two to fifty alternating positive and negative half-cells, although a greater number of cells can also be comprised. Due to the stacking of battery components, the plurality of half-cells described above is generally referred to as an electrochemical battery or an electrolytic battery, often referred to simply as a "battery". The method of construction of the battery pack and the thickness of the single cells are important factors in designing such a battery pack. In a typical battery pack arrangement known as a filter press design, each cell contains successive layers of non-conductive liner material. The successive layers include a frame that can accommodate electrode material and also incl...

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Problems solved by technology

In particular, it is desirable to obtain a high linear flow rate of the electrolyte inside the known cells, which implies a small cell spacing, but since the size of the cell spacing is defined by the thickness of the frame, this produces a corresponding undesired reduction in the effectiveness of the distribution channels. effect of depth, the distribution channel is generally recessed into one of the surfaces of the frame

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