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US 4,857,420 AGranted
Method of making monolithic solid oxide fuel cell stack
AssigneeInternational Fuel Cell Corporation
InventorsDonald L. Maricle, Richard F. Buswell
Life of this patent
Estimating the term…
Abstract
The fuel cell stack is made from two basic finished component subassemblies which are stacked repetitively atop each other in alternating fashion. One of the components is an electrode subassembly, and the other is a separator plate-flow field subassembly. The subassemblies are formed from several different material layers which are sintered and shrunk to operating size and density prior to the stack being assembled. The finished subassemblies are layered atop each other to form the stack and then heated to an elevated subsintering temperature and subjected to a light compressive load so that abutting surfaces of the adjacent subassemlies are creep flattened into intimate adherent contact with each other thereby forming a monolithic stack assembly.
Claims18
A method for forming a monolithic solid oxide fuel cell stack, said method comprising the steps of:
- (a) forming a plurality of electrode subassemblies by:
- (i) providing appropriately sized green unsintered tapes of solid oxide electrolyte material;
- (ii) sintering said tapes to form sintered plates of said electrolyte material of appropriate operational density;
- (iii) forming a finished layer of anode material on one surface of said sintered electrolyte plates;
- and
- (iv) forming a finished layer of cathode material on an opposite surface of said sintered electrolyte plates;
- (b) forming a plurality of gas separator-reactant flow field subassemblies by:
- (i) providing appropriately sized green unsintered sheets of interconnect material;
- (ii) sintering said sheets to form laminae of said interconnect material of appropriate operational density;
- (iii) forming a finished anode flow field layer of anode material on one surface of said laminae, said anode flow field layers including a plurality of parallel ribs and intervening grooves extending across said laminae in a first direction;
- and
- (iv) forming a finished cathode flow field layer on an opposite surface of said laminae, said cathode flow field layers including a plurality of parallel ribs and intervening grooves extending across said laminae in a second direction perpendicular to said first direction;
- (c) stacking said electrode subassemblies and said gas separator-reactant flow field subassemblies one atop the other in alternating fashion with said cathode material layers abutting said cathode flow field layers, and with anode material layers abutting said anode flow field layers to form a stack preassembly;
- (d) heating said stack preassembly to an elevated subsintering temperature thereby softening said subassemblies and creep flattening the latter to form intimate interfacial contact between said subassemblies;
- and
- (e) applying a light compressive load axially of said stack preassembly during said heating step to cause said subassemblies to fuse together to form a monolithic stack structure.
13 more elements
The method of claim I wherein said subsintering temperature is in the range of about 1000.degree. C. to about 1200.degree. C.
A method for forming a monolithic solid oxide fuel cell stack, said method comprising the steps of:
- (a) forming a plurality of electrodes subassemblies by:
- (i) providing appropriately sized green unsintered tapes of solid oxide electrolyte material;
- (ii) sintering said tapes at a temperature in the range of about 1400.degree. C. to about 1600.degree. C. to form sintered plates of said electrolyte material of appropriate operational density;
- (iii) forming a finished layer of anode material on one surface of said sintered electrolyte plates by plasma spraying said anode material onto said one surface of said plates;
- and
- (iv) forming a finished layer of cathode material on an opposite surface of said sintered electrolyte plates by plasma spraying said cathode material onto said opposite surface of said plates;
- (b) forming a plurality of gas separator-reactant flow field subassemblies by:
- (i) providing appropriately sized green unsintered sheets of interconnect material;
- (ii) sintering said sheets at a temperature in the range of about 1650.degree. C. to about 1750.degree. C. to form sintered laminae of said interconnect material of appropriate operational density;
- (iii) forming a finished anode flow field layer of anode material on one surface of said laminae by plasma spraying said anode material onto said one surface of said laminae;
- and
- (iv) forming a finished cathode flow field layer of cathode material on an opposite surface of said laminae by plasma spraying said cathode material onto said opposite surface of said laminae;
- (c) stacking said electrode subassemblies and said gas separator-reactant flow field subassemblies one atop the other in alternating fashion with said cathode material layers abutting said cathode flow field layers, and with said anode material layers abutting said anode flow field layers to form a stack preassembly;
- and
- (d) heating said stack preassembly to a subsintering temperature in the range of about 1000.degree. C. to about 1200.degree. C. while applying a relatively light compressive load to said stack preassembly to creep flatten said subassemblies into intimate interfacial contact with each other and to cause said subassemblies to fuse together to form a monolithic stack structure.
12 more elements
A method for making a solid oxide fuel cell stack subassembly for use in forming a monolithic solid oxide fuel cell stack, said method comprising the steps of:
- (a) providing a thin planar body of green unsintered ceramic interconnect material which forms a core sheet for said subassembly;
- (b) sintering said body of green unsintered ceramic material to form a sintered sheet of ceramic material of appropriate operational density;
- (c) plasma spraying a layer of cathode material onto one side of said sintered sheet of ceramic material, and forming raised ribs with intervening grooves;
- and
- (d) plasma spraying a layer of anode material onto an opposite side of said sintered sheet of ceramic material, and forming raised ribs with intervening grooves the result being a shelf supporting gas separator - reactant field subassembly having a sintered ceramic core sheet and opposed outer layers of cathode and anode material, all of which are of appropriate operational density for use in a solid oxide fuel cell stack.
2 more elements
A self supporting finished subassembly for use in forming a monolithic solid oxide fuel cell stack, said subassembly comprising:
- (a) a core sheet of ceramic interconnect material which has been sintered to fuse said ceramic material into a coherent mass of appropriate operational density suitable for use in a fuel cell stack;
- (b) a layer of anode material applied to one side of said core sheet after the latter has been sintered, to form a coherent first outer layer of anode material, with raised ribs and intervening grooves, of appropriate operational density suitable for use in a fuel cell stack;
- and
- (c) a layer of cathode material applied to an opposite side of said core sheet after the latter has been sintered, to form a coherent second outer layer of cathode material, with raised ribs and intervening grooves, of appropriate operational density suitable for use in a fuel cell stack, said subassembly being coherent and self supporting gas separator - reactant flow field subassembly and operable for building a solid oxide fuel cell stack by stacking the subassemblies one atop another.
1 more element
Dependencies are inferred from the claim text.