Apparatus and method of fabricating a monolithic solid oxide fuel cell

A method of constructing a fuel cell comprising the steps of:

• mixing ceramic powders required to make an anode, a cathode, an electrolyte, and an interconnect each individually with a binder system to form a batch of each of said materials;
• forming thin tapes of each of said materials;
• attaching said anode tape onto said electrolyte tape and said cathode tape on an opposite side of said electrolyte tape to form a trilayer electrolyte tape;
• forming a plurality of parallel fuel and oxidant passageways extending along said anode and said cathode respectively;
• cutting said trilayer electrolyte tape to form a plurality of trilayer electrolyte elements having a desired gross net shape;
• cutting said interconnect tape to form a plurality of interconnect elements having a desired gross net shape;
• heating said trilayer electrolyte elements and said interconnect elements to a temperature and for a duration sufficient to cause removal of the binder system and to partially sinter the respective ceramic materials to a percentage of the desired final density for said respective materials such that subsequent heating and sintering will result in a compatible shrinkage of all of said ceramic materials;
• cooling said at least partially sintered trilayer electrolyte and interconnect elements;
• wetting one surface of said interconnect elements and a surface of said anode of said trilayer electrolyte elements with an anode bonding agent, said anode bonding agent including powders of said anode ceramic material, interconnect ceramic materials, binder system materials, and a solvent mixed into a viscous slurry;
• wetting the opposite surface of said interconnect elements and the surface of said cathode of said trilayer electrolyte elements with a cathode bonding agent, said cathode bonding agent including powders of said cathode ceramic material, interconnect ceramic materials, binder system materials, and a solvent mixed into a viscous slurry;
• stacking a plurality of said at least partially sintered trilayer electrolyte elements alternately with a plurality of said partially sintered interconnect elements to form a stacked array;
• and
• processing said stacked array to bond the contacting surfaces of said alternately stacked trilayer electrolyte and interconnect elements.

A method of constructing a monolithic solid oxide fuel cell having a plurality of stacked cells, each cell including a cathode, an electrolyte, and an anode, said cells being separated from one another by an interconnect, comprising the steps of:

• assembling a plurality of trilayer electrolyte elements each including respective layers of at least partially but not completely sintered cathode ceramic materials, electrolyte ceramic materials, and anode ceramic materials, said trilayer electrolyte elements including fuel and oxidant flow pathways formed into the respective surfaces of said anode layer and said cathode layer by displacing contiguous portions of said surfaces from the plane of the pre-existing flat surface leaving raised surface portions, said trilayer electrolyte elements having a desired configuration;
• forming a plurality of interconnect elements each including at least partially but not completely sintered interconnect ceramic materials in a desired configuration;
• wetting one surface of said interconnect elements and the surface of said anode of said trilayer electrolyte elements with an anode bonding agent, said anode bonding agent including powders of said anode ceramic material, said interconnect ceramic materials, a binder system materials, and a solvent mixed into a viscous slurry;
• wetting the opposite surface of said interconnect elements and the surface of said cathode of said trilayer electrolyte elements with a cathode bonding agent, said cathode bonding agent including powders of said cathode ceramic material, said interconnect ceramic material, said binder system materials, and a solvent mixed into a viscous slurry;
• stacking a plurality of said at least partially sintered trilayer electrolyte elements alternately with a plurality of said interconnect elements to form a stacked array;
• and
• processing said stacked array to bond contacting surfaces of said alternately stacked trilayer electrolyte and interconnect elements.

A method of constructing a monolithic solid oxide fuel cell having a plurality of stacked cells, each cell including a cathode, an electrolyte, and an anode, said cells being separated from one another by an interconnect, comprising the steps of:

• assembling a plurality of electrolyte trilayer elements each including respective layers of cathode ceramic materials, electrolyte ceramic materials, and anode ceramic materials, in a desired configuration;
• forming a plurality of interconnect trilayer elements each including anode ceramic materials and cathode ceramic materials sandwiching therebetween interconnect ceramic materials in a desired configuration;
• bonding one of said electrolyte trilayer elements and one of said interconnect trilayer elements together such that only one of said anode and said cathode ceramic materials is sandwiched between electrolyte ceramic material and interconnect ceramic material;
• heating said bonded pairs of electrolyte and interconnect trilayer elements to a temperature sufficient to at least partially but not completely sinter said respective ceramic materials to form cell elements;
• stacking a plurality of said cell elements to form a stacked array;
• and
• processing said stacked array to bond the contacting surfaces of said stacked cell elements.

An apparatus for constructing a monolithic solid oxide fuel cell having a plurality of stacked cells, each cell including a cathode, an electrolyte, and an anode, said cells being separated from one another by an interconnect, the apparatus comprising:

• a plurality of electrolyte elements each including respective layers of cathode ceramic materials, electrolyte ceramic materials, and anode ceramic materials all being partially sintered, said electrolyte elements configured to include fuel and oxidant flow pathways, said electrolyte elements shaped in a desired configuration;
• a plurality of interconnect elements each including interconnect ceramic materials in a desired configuration and being partially sintered,
• alternately stacking said interconnect elements with said plurality of electrolyte elements to form a stacked array;
• and
• bonding agent means for bonding said partially sintered interconnect elements to said partially sintered electrolyte elements.

A bonding agent for use in bonding the contacting surfaces of ceramic elements of a monolithic solid oxide fuel cell which ceramic elements are at least partially but not completely sintered, said bonding agent comprising:

• ceramic materials selected from the group consisting of anode ceramics, cathode ceramics, and interconnect ceramics;
• a binder selected from the group consisting of synthetic rubber, plastics, polyvinyl alcohol, polyvinyl butyryl resin, and polymer systems which thermally decompose without cross linking;
• a plasticizer selected from the group consisting of butyl benzyl phthalate and solvents of the phthalate group;
• and
• a solvent, said ceramic material, said binder, said plasticizer, and said solvent mixed together to form a viscous slurry.

A monolithic solid oxide fuel cell constructed according to the process steps of:

• mixing ceramic powders required to make an anode, a cathode, an electrolyte, and an interconnect each individually with a binder system to form a batch of each of said materials;
• forming thin tapes of each of said material batches;
• attaching said anode tape onto said electrolyte tape and said cathode tape on an opposite side of said electrolyte tape to form a trilayer electrolyte tape;
• shaping said trilayer electrolyte tape to form fuel flow pathways extending along said anode, and oxidant flow pathways extending along said cathode of said trilayer electrolyte tape;
• cutting said trilayer electrolyte tape to form a plurality of trilayer electrolyte elements having a desired gross net shape;
• cutting said interconnect tape to form a plurality of interconnect elements having a desired gross net shape;
• heating said trilayer electrolyte elements and said interconnect elements to a temperature sufficient to cause removal of the binder system and initiate sintering of the respective ceramic materials to a partially sintered condition;
• stacking a plurality of said partially sintered trilayer electrolyte elements alternately with a plurality of said partially sintered interconnect elements, subsequent to said heating step, to form a stacked array;
• and
• processing said stacked array to bond contacting surfaces of said alternately stacked trilayer electrolyte and interconnect elements.

A monolithic solid oxide fuel cell constructed according to the process steps of:

• mixing ceramic powders required to make an anode, a cathode, an electrolyte, and an interconnect each individually with a binder system to form a batch of each of said materials;
• forming thin tapes of each of said materials;
• attaching said anode tape onto said electrolyte tape and said cathode tape on an opposite side of said electrolyte tape to form a trilayer electrolyte tape;
• forming a plurality of parallel fuel and oxidant passageways extending along said anode and said cathode respectively;
• cutting said trilayer electrolyte tape to form a plurality of trilayer electrolyte elements having a desired gross net shape;
• cutting said interconnect tape to form a plurality of interconnect elements having a desired gross net shape;
• heating said trilayer electrolyte elements and said interconnect elements to a temperature and for a duration sufficient to cause removal of the binder system and to partially sinter the respective ceramic materials to a percentage of the desired final density for said respective materials such that subsequent heating and sintering will result in a compatible shrinkage of all of said ceramic materials;
• cooling said at least partially sintered trilayer electrolyte and interconnect elements;
• wetting one surface of said interconnect elements and a surface of said anode of said trilayer electrolyte elements with an anode bonding agent, said anode bonding agent including powders of said anode ceramic material, interconnect ceramic materials, binder system materials, and a solvent mixed into a viscous slurry;
• wetting the opposite surface of said interconnect elements and the surface of said cathode of said trilayer electrolyte elements with a cathode bonding agent, said cathode bonding agent including powders of said cathode ceramic material, interconnect ceramic materials, binder system materials, and a solvent mixed into a viscous slurry;
• stacking a plurality of said at least partially sintered trilayer electrolyte elements alternately with a plurality of said partially sintered interconnect elements to form a stacked array;
• and
• processing said stacked array to bond the contacting surfaces of said alternately stacked trilayer electrolyte and interconnect elements.

A monolithic solid oxide fuel cell having a plurality of stacked cells, each cell including a cathode, an electrolyte, and an anode, said cells being separated from one another by an interconnect, constructed according to the process steps of:

• assembling a plurality of trilayer electrolyte elements each including respective layers of at least partially but not completely sintered cathode ceramic materials, electrolyte ceramic materials, and anode ceramic materials, said trilayer electrolyte elements including fuel and oxidant flow pathways formed into the respective surfaces of said anode layer and said cathode layer by displacing contiguous portions of said surfaces from the plane of the pre-existing flat surface leaving raised surface portions, said trilayer electrolyte elements having a desired configuration;
• forming a plurality of interconnect elements each including at least partially but not completely sintered interconnect ceramic materials in a desired configuration;
• wetting one surface of said interconnect elements and the surface of said anode of said trilayer electrolyte elements with an anode bonding agent, said anode bonding agent including powders of said anode ceramic material, said interconnect ceramic materials, a binder system materials, and a solvent mixed into a viscous slurry;
• wetting the opposite surface of said interconnect elements and the surface of said cathode of said trilayer electrolyte elements with a cathode bonding agent, said cathode bonding agent including powders of said cathode ceramic material, said interconnect ceramic material, said binder system materials, and a solvent mixed into a viscous slurry;
• stacking a plurality of said at least partially sintered trilayer electrolyte elements alternately with a plurality of said interconnect elements to form a stacked array;
• and
• processing said stacked array to bond the contacting surfaces of said alternately stacked trilayer electrolyte and interconnect elements.

A method of making a monolithic ceramic solid oxide fuel cell having a plurality of electrolyte trilayer walls each of electrolyte ceramic sandwiched between opposite layers of anode and cathode ceramic, said electrolyte trilayer walls being alternately stacked with plural walls of interconnect ceramic to cooperatively define fuel and oxidant passageways;

• said method comprising the steps of:
• partially sintering said electrolyte trilayer walls;
• partially sintering said interconnect walls;
• alternately stacking said partially sintered trilayer walls with said partially sintered interconnect walls;
• and
• finish sintering said alternately stacked walls to interbond the latter into a ceramic monolith.