Abstract: A fuel cell stack (10) comprises a plurality of fuel cells each with a chamber (K) for electrolyte with at least one inlet (114) and at least one outlet (116), and an inlet header (45) to supply electrolyte to all the cells in parallel. Each cell comprises a first plate (12) to define the electrolyte chamber (K), a second plate (13) to define an oxidizing gas chamber (0) and a third plate (14) to define a fuel gas chamber (H), each of these plates (12-14) also defining a side chamber (36) adjacent to but sealed from the corresponding chambers (K, 0, H), so the side chambers (36) defines an electrolyte outlet channel.

Abstract: A liquid electrolyte fuel cell system (10) comprises at least one fuel cell with a liquid electrolyte chamber between opposed electrodes, the electrodes being an anode and a cathode, and means (30, 32) for supplying a gas stream to a gas chamber adjacent to the cathode and withdrawing a spent gas stream (38) from the gas chamber adjacent to the cathode, the system also comprising a liquid electrolyte storage tank (40), and means (42, 44, 47, 48) to circulate liquid electrolyte between the liquid electrolyte storage tank (40) and the fuel cells. In addition the system comprises a water storage tank (60) adjacent to the storage tank (40), and means (50, 51) for condensing water vapor from the spent gas stream (38), and for feeding (56) the condensed water vapor into the water storage tank (60). The water storage tank (60) has an overflow outlet (64); and a communication duct (68) linking the liquid electrolyte storage tank (40) and the water storage tank (60) below the level of the overflow outlet (60).

Abstract: A liquid electrolyte fuel cell comprises means to define an electrolyte chamber (208), and two electrodes (10), one on either side of the electrolyte chamber (208), each electrode comprising:—a sheet (11) of metal through which are defined a multiplicity of through-holes (14), and—a gas-permeable layer (16) of fibrous and/or particulate electrically-conductive material which is bonded to and in electrical contact with the sheet of metal (11), and which comprises catalytic material (18). The electrode (10) may be arranged such that the gas-permeable layer (16) faces the electrolyte chamber (208).

Abstract: A fuel cell stack (10) comprises a plurality of fuel cells each with a chamber (K) for electrolyte with at least one inlet and at least one outlet, and at least one header (30) to supply electrolyte to all the cells in parallel, and means (14) to collect electrolyte that has flowed through the cells. For each cell, the electrolyte outlets (34) feed into an electrolyte flow channel arranged such that in use there is a free surface of electrolyte within the electrolyte flow channel, the electrolyte flow channel being separate from the corresponding electrolyte flow channels for other cells, but such that the free surfaces of all the electrolyte flow channels are at a common pressure. Electrolyte is maintained at a constant depth in this open flow channel by a weir (38), and then flows over the weir to trickle or drip down the outside of the stack.

Abstract: A liquid electrolyte fuel cell system (10) comprises at least one fuel cell with a liquid electrolyte chamber between opposed electrodes, the electrodes being an anode and a cathode, and means (30, 32) for supplying a gas stream to a gas chamber adjacent to the cathode and withdrawing a spent gas stream (38) from the gas chamber adjacent to the cathode, the system also comprising a liquid electrolyte storage tank (40), and means (42, 44, 47, 48) to circulate liquid electrolyte between the liquid electrolyte storage tank (40) and the fuel cells. In addition the system comprises a water storage tank (60) adjacent to the storage tank (40), and means (50, 51) for condensing water vapour from the spent gas stream (38), and for feeding (56) the condensed water vapour into the water storage tank (60). The water storage tank (60) has an overflow outlet (64); and a communication duct (68) linking the liquid electrolyte storage tank (40) and the water storage tank (60) below the level of the overflow outlet (60).

Abstract: A liquid electrolyte fuel cell comprises means to define an electrolyte chamber, and electrodes on opposite sides of the electrolyte chamber. The electrode comprises an electrically conductive sheet (10) through which are defined a multiplicity of through-pores or holes (14). These may be formed by laser drilling through the sheet. The electrode would normally also include a layer (16) of catalytic material. The margin (15) of the sheet is not perforated or porous, to simplify sealing.

Abstract: A system (10) for supplying a liquid electrolyte to cell stacks (32) arranged at a plurality of different heights comprises a plurality of constant head supply tanks (12) for containing liquid electrolyte, one for each of the different heights. Each such supply tank (12) is adapted to ensure that the surface of the liquid electrolyte is at atmospheric pressure, and to feed electrolyte to a cell stack, and incorporates an overflow duct (18) to keep the electrolyte at a constant level. For each supply tank (12) except the lowest, the overflow duct (18) supplies overflowing electrolyte to a supply tank at a lower height. The system also includes an electrolyte storage tank (20), and means (24, 26) to supply electrolyte from the storage tank (20) to the highest supply tank (12).

Abstract: A fuel cell stack (10) comprises a plurality of fuel cells each with a chamber (K) for electrolyte with at least one inlet and at least one outlet, and at least one header (30) to supply electrolyte to all the cells in parallel, and means (14) to collect electrolyte that has flowed through the cells. For each cell, the electrolyte outlets (34) feed into an electrolyte flow channel arranged such that in use there is a free surface of electrolyte within the electrolyte flow channel, the electrolyte flow channel being separate from the corresponding electrolyte flow channels for other cells, but such that the free surfaces of all the electrolyte flow channels are at a common pressure. Electrolyte is maintained at a constant depth in this open flow channel by a weir (38), and then flows over the weir to trickle or drip down the outside of the stack.

Abstract: A system (10) for supplying a liquid electrolyte to cell stacks (32) arranged at a plurality of different heights comprises a plurality of constant head supply tanks (12) for containing liquid electrolyte, one for each of the different heights. Each such supply tank (12) is adapted to ensure that the surface of the liquid electrolyte is at atmospheric pressure, and to feed electrolyte to a cell stack, and incorporates an overflow duct (18) to keep the electrolyte at a constant level. For each supply tank (12) except the lowest, the overflow duct (18) supplies overflowing electrolyte to a supply tank at a lower height. The system also includes an electrolyte storage tank (20), and means (24, 26) to supply electrolyte from the storage tank (20) to the highest supply tank (12).

Abstract: A liquid electrolyte fuel cell comprises means to define an electrolyte chamber, and electrodes on opposite sides of the electrolyte chamber. The electrode comprises an electrically conductive sheet (10) through which are defined a multiplicity of through-pores or holes (14). These may be formed by laser drilling through the sheet. The electrode would normally also include a layer (16) of catalytic material. The margin (15) of the sheet is not perforated or porous, to simplify sealing.

Abstract: An electrode for use in a fuel cell consists of a porous plastic substrate, a conductive layer and a catalyst layer, in which the substrate is hydrophilic. Preferably the substrate has a water wicking rate no less than 40 mm per 600 s. Such an electrode may be used in a fuel cell, with an electrolyte chamber (8) defined between two opposed electrodes (11, 12), the electrodes having the catalyst layers (5) facing away from the electrolyte in contact with respective gas chambers (7, 9). Preferably the electrolyte is maintained at a negative pressure during operation.

Abstract: An electrode for use in a fuel cell consists of a porous plastic substrate, a conductive layer and a catalyst layer, in which the substrate is hydrophilic. Preferably the substrate has a water wicking rate no less than 40 mm per 600 s. Such an electrode may be used in a fuel cell, with an electrolyte chamber (8) defined between two opposed electrodes (11, 12), the electrodes having the catalyst layers (5) facing away from the electrolyte in contact with respective gas chambers (7, 9). Preferably the electrolyte is maintained at a negative pressure during operation.

Abstract: A fuel cell assembly comprises a fuel cell stack (200) comprising a plurality of fuel cells, a releasable clamp (235) to retain the components of the fuel cell stack; and a casing (240) into which the stack is insertable. The casing (240) provides means (250, 252) to compress the fuel cell stack components together. Each fuel cell in the stack (200) comprises two electrodes (11, 12) that are mutually spaced so as to form an electrolyte chamber therebetween, and each electrode incorporates a catalyst; the fuel cell stack is made up of plates (202) to define electrolyte chambers and plates (206) to define the gas chambers, the electrodes being sealingly secured between plates in the stack. At least one end plate (230) defines ports (232) to supply or withdraw fluids from the fuel cells.

Abstract: A fuel cell assembly comprises a fuel cell stack (160) with at least one fuel cell (10), and a pump (50). Each fuel cell (10) includes a first gas chamber, an electrolyte chamber, and a second gas chamber, and two electrodes separating the electrolyte chamber from the gas chambers. The pump (50) is arranged to reduce the pressure of an electrolyte (40) in the electrolyte chamber to a negative pressure. This negative pressure may be adjusted in accordance with the electrical output of the fuel cell stack (160).