Fuel cell comprising at least two stacked printed circuit boards with a plurality of interconnected fuel cell units

Abstract

A fuel cell comprising at least two stacked fuel cell boards ( 22 ) which each comprise a membrane of substantially gas impervious electrolyte material and at least two electrode pairs wherein the anode and cathode of each said electrode pair are arranged on respective faces of said membrane. An electrode of each pair of electrodes is connected to an electrode of an adjacent pair of electrodes by a through-membrane connection ( 13 ) or by an external connection on a Printed Circuit Board, comprising an electrically conductive region of said electrolyte material. A method for forming the through-membrane electrical connections in the electrolyte membrane is also disclosed.

What is claimed is: 
     
         1 . A fuel cell comprising at least two fuel cell boards, each individually switchable by providing at least one switch on each of said fuel cell boards. 
     
     
         2 . The fuel cell as claimed in  claim 1 , wherein when the fuel cell boards in the fuel cell are stacked, adjacent fuel cell boards in the stack are separated by an insulating spacer. 
     
     
         3 . The fuel cell as claimed in  claim 2 , wherein the spacer has integrated coolant conduits which run substantially perpendicular to planar surfaces of the fuel cell boards. 
     
     
         4 . The fuel cell as claimed in  claim 2 , wherein the spacer is shaped to assist the distribution of reactants. 
     
     
         5 . The fuel cell as claimed in  claim 2 , further comprising water supply or extraction conduits. 
     
     
         6 . The fuel cell as claimed in  claim 1 , wherein each fuel cell board comprises a plurality of anodes and a plurality of cathodes and wherein on each face of each fuel cell board, the sequence of anodes and cathodes alternates such that each anode, except the anode on edge of the fuel cell board, lies between two cathodes, and each cathode, except the cathode on edge of the fuel cell board, lies between two anodes, and the cathodes of two adjacent fuel cell boards lie substantially opposite each other. 
     
     
         7 . A fuel cell as claimed in  claim 6 , wherein a first reactant is delivered to a pair of anodes on a first and second adjacent fuel cell boards by means of a single first reactant distribution channel on one reactant distribution layer, and a second reactant is delivered to a pair of cathodes on said first and second adjacent fuel cell boards by means of a single second reactant distribution channel on said reactant distribution layer. 
     
     
         8 . The fuel cell as claimed in  claim 1 , wherein each face of each fuel cell board carries either only anodes or only cathodes, and the fuel cell boards in the fuel cell are arranged so that the anodes of two adjacent fuel cell boards lie substantially opposite each other, and the cathodes of two adjacent fuel cell boards lie substantially opposite each other. 
     
     
         9 . A method of controlling the power output profile of a fuel cell having at least two fuel cell boards comprising selectively switching one or more fuel cell board. 
     
     
         10 . A method as claimed in  claim 9 , comprising the step of switching fuel cell boards according to a duty cycle. 
     
     
         11 . A method as claimed in  claim 9 , further comprising depositing a corrosion resistant layer onto the surface of a current collection and/or distribution layer of a fuel cell. 
     
     
         12 . The method of  claim 11 , wherein the corrosion resistant layer is formed by applying an ink comprising a conducting polymer or a conductive metal oxide, or carbon conductive ink, to the surface of a current collection and/or distribution layer. 
     
     
         13 . The method of  claim 12 , wherein the conducting polymer is selected from polyaniline, polypyrrole, polythiophene and poly(3,4-ethylenedioxythiophene) (PEDOT). 
     
     
         14 . The method of  claim 12 , wherein the conductive metal oxide is selected from Ti4O7; Ti0.9Nb0.1O2; or tin oxide doped with antimony, fluorine, or indium. 
     
     
         15 . The method of  claim 12 , wherein the conductive polymer has a perfluorinated substituent, especially where that perfluorinated substituent is a perfluorinated aliphatic chain, or contains perfluorinated aliphatic chains. 
     
     
         16 . The method of  claim 12 , wherein the monomers forming the conductive polymer comprise a perfluorinated alkyl chain. 
     
     
         17 . The method of  claim 12 , wherein the surface of a current collection and/or distribution layer undergoes direct derivatisation of its surface, utilising a silane or diazo reagent to form a corrosion resistant layer. 
     
     
         18 . The method of  claim 17 , wherein the silane or diazo reagent comprises perfluoro properties. 
     
     
         19 . The method of  claim 18  wherein the silane or diazo reagent comprises a pefluorinated benzene, or an aryl ring further comprising a perfluorinated alkyl chain. 
     
     
         20 . The method of  claim 10 , wherein a combination of corrosion resistant layers is applied to the surface of a current collection and/or distribution layer, the method comprising the step of applying an ink to the surface of a current collection and/or distribution layer, and/or electrodepositing a conductive polymer onto the surface of a current collection and/or distribution layer, and/or direct derivatisation of the surface of a current collection and/or distribution layer, with a silane or diazo reagent. 
     
     
         21 . The fuel cell of  claim 1 , wherein each fuel cell board comprises a printed circuit board. 
     
     
         22 . A fuel cell comprising at least two fuel cell boards, each individually switchable by providing at least one switch on each of said fuel cell boards, wherein when the fuel cell boards in the fuel cell are stacked, adjacent fuel cell boards in the stack are separated by an insulating spacer, wherein the spacer has integrated coolant conduits which run substantially perpendicular to planar surfaces of the fuel cell boards. 
     
     
         23 . The fuel cell as claimed in  claim 17 , wherein each fuel cell board comprises a plurality of anodes and a plurality of cathodes and wherein on each face of each fuel cell board, the sequence of anodes and cathodes alternates such that each anode, except the anode on edge of the fuel cell board, lies between two cathodes, and each cathode, except the cathode on edge of the fuel cell board, lies between two anodes, and the cathodes of two adjacent fuel cell boards lie substantially opposite each other. 
     
     
         24 . The fuel cell as claimed in  claim 17 , wherein each face of each fuel cell board carries either only anodes or only cathodes, and the fuel cell boards in the fuel cell are arranged so that the anodes of two adjacent fuel cell boards lie substantially opposite each other, and the cathodes of two adjacent fuel cell boards lie substantially opposite each other.