Ceramic interconnect for fuel cell stacks

Abstract

A fuel cell comprises a plurality of sub-cells, each sub-cell including a first electrode in fluid communication with a source of oxygen gas, a second electrode in fluid communication with a source of a fuel gas, and a solid electrolyte between the first electrode and the second electrode. The sub-cells are connected with each other with an interconnect. The interconnect includes a first layer in contact with the first electrode of each cell, and a second layer in contact with the second electrode of each cell. The first layer includes a (La,Mn)Sr-titanate based perovskite represented by the empirical formula of La y Sr (1−y) Ti (1−x) Mn x O b . In one embodiment, the second layer includes a (Nb,Y)Sr-titanate perovskite represented by the empirical formula of Sr (1−1.5z−0.5k±δ) Y z Nb k Ti (1−k) O d . In another embodiment, the interconnect has a thickness of between about 10 μm and about 100 μm, and the second layer of the interconnect includes a (La)Sr-titanate based perovskite represented by the empirical formula of Sr (1−z±δ) La z TiO d .

1 . A fuel cell, comprising:
 a) a plurality of sub-cells, each sub-cell including
 i) a first electrode in fluid communication with a source of oxygen gas, 
 ii) a second electrode in fluid communication with a source of a fuel gas, and 
 iii) a solid electrolyte between the first electrode and the second electrode; and 
   b) an interconnect between the sub-cells, the interconnect including
 i) a first layer that includes a (La,Mn)Sr-titanate based perovskite represented by the empirical formula of La y Sr (1−y) Ti (1−x) Mn x O b , wherein
 x is equal to or greater than zero and equal to or less than 0.6, 
 y is equal to or greater than 0.2 and equal to or less than 0.8, and 
 b is equal to or greater than 2.5 and equal to or less than 3.5, 
 
 wherein the first layer is in contact with the first electrode of each sub-cell, and 
 ii) a second layer that includes a (Nb, Y)Sr-titanate based perovskite represented by the empirical formula of Sr (1−1.5z−0.5k±δ) Y z Nb k Ti (1−k) O d , wherein
 each of k and z independently is equal to or greater than zero and equal to or less than 0.2, 
 d is equal to or greater than 2.5 and equal to or less than 3.5, and 
 δ is equal to or greater than zero and equal to or less than 0.05, 
 
 wherein the second layer is in contact with the second electrode of each sub-cell. 
   
   
   
       2 . The fuel cell of  claim 1 , wherein the (La,Mn)Sr-titanate based perovskite is represented by the empirical formula of La 0.4 Sr 0.6 Ti (1−x) Mn x O b . 
   
   
       3 . The fuel cell of  claim 1 , wherein each of the first and second electrodes is porous. 
   
   
       4 . The fuel cell of  claim 3 , wherein the interconnect is substantially planar. 
   
   
       5 . The fuel cell of  claim 4 , wherein the solid electrolyte includes at least one material selected from the group consisting of ZrO 2  based material, CeO 2  based material and lanthanide-gallate based material. 
   
   
       6 . The fuel cell of  claim 4 , wherein the first electrode includes at least one of a lanthanum strontium manganate (LSM) based material and a lanthanum strontium cobalt ferrite (LSCF) based material. 
   
   
       7 . The fuel cell of  claim 4 , wherein the second electrode includes a Ni cermet. 
   
   
       8 . The fuel cell of  claim 4 , wherein the thickness of each of the first and second electrodes of at least one of the cells is in a range of between about 0.5 mm and about 2 mm. 
   
   
       9 . The fuel cell of  claim 8 , wherein the thickness of the interconnect is in a range of between about 5 μm and about 1,000 μm. 
   
   
       10 . The fuel cell of  claim 9 , wherein the thickness of the interconnect is in a range of between about 10 μm and about 500 μm. 
   
   
       11 . The fuel cell of  claim 10 , wherein the thickness of the interconnect is in a range of between about 10 μm and about 200 μm. 
   
   
       12 . The fuel cell of  claim 11 , wherein the thickness of the interconnect is in a range of between about 10 μm and about 100 μm. 
   
   
       13 . A fuel cell, comprising:
 a) a plurality of sub-cells, each sub-cell including
 i) a first electrode in fluid communication with a source of oxygen gas, 
 ii) a second electrode in fluid communication with a source of a fuel gas, and 
 iii) a solid electrolyte between the first electrode and the second electrode; and 
   b) an interconnect between the sub-cells and having a thickness of between about 10 μm and about 100 μm, the interconnect including
 i) a first layer that includes a (La,Mn)Sr-titanate based perovskite represented by the empirical formula of La y Sr (1−y) Ti (1−x) Mn x O b , wherein
 x is equal to or greater than zero and equal to or less than 0.6, 
 y is equal to or greater than  0 . 2  and equal to or less than 0.8, and 
 b is equal to or greater than 2.5 and equal to or less than 3.5, 
 
 wherein the first layer is in contact with the first electrode of each sub-cell; and 
 ii) a second layer that includes a (La)Sr-titanate based perovskite represented by the empirical formula of Sr (1−z±δ) La z TiO d , wherein
 z is equal to or greater than zero and equal to or less than 0.4, 
 d is equal to or greater than 2.5 and equal to or less than 3.5, and 
 δ is equal to or greater than zero and equal to or less than 0.05, 
 
 wherein the second layer is in contact with the second electrode of each sub-cell. 
   
   
   
       14 . The fuel cell of  claim 13 , wherein the (La,Mn)Sr-titanate-based perovskite is represented by the empirical formula of La 0.4 Sr 0.6 Ti (1−x) Mn x O b . 
   
   
       15 . The fuel cell of  claim 13 , wherein each of the first and second electrodes is porous. 
   
   
       16 . The fuel cell of  claim 15 , wherein the interconnect is substantially planar. 
   
   
       17 . The fuel cell of  claim 16 , wherein the solid electrolyte includes at least one material selected from the group consisting of ZrO 2  based material, CeO 2  based material and lanthanide-gallate based material. 
   
   
       18 . The fuel cell of  claim 16 , wherein the first electrode includes at least one of a lanthanum strontium manganate (LSM) based material and a lanthanum strontium cobalt ferrite (LSCF) based material. 
   
   
       19 . The fuel cell of  claim 16 , wherein the second electrode includes a Ni cermet. 
   
   
       20 . The fuel cell of  claim 16 , wherein the thickness of each of the first and second electrodes of at least one of the cells is in a range of between about 0.5 mm and about 2 mm. 
   
   
       21 . The fuel cell of  claim 20 , wherein the thickness of the interconnect is in a range of between about 10 μm and about 75 μm. 
   
   
       22 . The fuel cell of  claim 21 , wherein the thickness of the interconnect is in a range of between about 15 μm and about 65 μm. 
   
   
       23 . A method of forming a fuel cell that includes a plurality of sub-cells, comprising the step of connecting each of the sub-cells with an interconnect, wherein each sub-cell includes:
 i) a first electrode in fluid communication with a source of oxygen gas,   ii) a second electrode in fluid communication with a source of a fuel gas, and    iii) a solid electrolyte between the first electrode and the second electrode, and   wherein the interconnect includes   i) a first layer that includes a (La,Mn)Sr-titanate-based perovskite represented by the empirical formula of La y Sr (1−y) Ti (1−x) Mn x O b , wherein
 x is equal to or greater than zero and equal to or less than 0.6, 
 y is equal to or greater than 0.2 and equal to or less than 0.8, and 
 b is equal to or greater than 2.4 and equal to or less than 3.3, 
    wherein the first layer is in contact with the first electrode of each sub-cell, and   ii) a second layer that includes a (Nb,Y)Sr-titanate-based perovskite represented by the empirical formula of Sr (1−1.5z−0.5k±δ) Y z Nb k Ti (1−k) O d , wherein
 each of k and z independently is equal to or greater than zero and equal to or less than 0.2, 
 d is equal to or greater than 2.5 and equal to or less than 3.5, and 
 δ is equal to or greater than zero and equal to or less than 0.05, 
    wherein the second layer is in contact with the second electrode of each sub-cell.   
   
   
       24 . The method of  claim 23 , further including forming at least one component of each sub-cell. 
   
   
       25 . The method of  claim 24 , further including forming at least one of the electrodes of each sub-cell, and forming the interconnect. 
   
   
       26 . The method of  claim 25 , wherein at least one of the electrodes of each sub-cell is formed independently from the formation of the interconnect. 
   
   
       27 . The method of  claim 25 , wherein at least one of the electrodes of each sub-cell is formed together with the formation of the interconnect. 
   
   
       28 . The method of  claim 26 , wherein the first electrode of a first sub-cell of the plurality of sub-cells is formed together with the first and the second layers of the interconnect, and wherein the formation of the first electrode, the first layer and the second layer includes:
 i) disposing a second-layer material of the interconnect over the second electrode of a first sub-cell;   ii) disposing a first-layer material of the interconnect over the second-layer material;   iii) disposing a first-electrode material of a second sub-cell over the first-layer of the interconnect; and   iv) heating the materials such that the first-layer and second-layer materials of the interconnect form the first and second layers of the interconnect, respectively, and that the first-electrode material forms the first electrode.   
   
   
       29 . A method of forming a fuel cell that includes a plurality of sub-cells, comprising the step of connecting each of the sub-cells with an interconnect having a thickness of between about 10 μm and about 100 μm, wherein each sub-cell includes:
 i) a first electrode in fluid communication with a source of oxygen gas,   ii) a second electrode in fluid communication with a source of a fuel gas, and   iii) a solid electrolyte between the first electrode and the second electrode, and   wherein the interconnect includes   i) a first layer that includes a (La,Mn)Sr-titanate-based perovskite represented by the empirical formula of La y Sr (1−y) Ti (1−x) Mn x O b , wherein
 x is equal to or greater than zero and equal to or less than 0.6, 
 y is equal to or greater than 0.2 and equal to or less than 0.8, and 
 b is equal to or greater than 2.5 and equal to or less than 3.5, 
    wherein the first layer is in contact with the first electrode of each sub-cell, and   ii) a second layer that includes a (La)Sr-titanate based perovskite represented by the empirical formula of Sr (1−z±δ) La z TiO d , wherein
 z is equal to or greater than zero and equal to or less than 0.4, 
 d is equal to or greater than 2.5 and equal to or less than 3.5, and 
 δ is equal to or greater than zero and equal to or less than 0.05, 
   wherein the second layer is in contact with the second electrode of each sub-cell.   
   
   
       30 . The method of  claim 29 , further including forming at least one component of each sub-cell. 
   
   
       31 . The method of  claim 30 , further including forming at least one of the electrodes of each sub-cell, and forming the interconnect. 
   
   
       32 . The method of  claim 31 , wherein at least one of the electrodes of each sub-cell is formed independently from the formation of the interconnect. 
   
   
       33 . The method of  claim 31 , wherein at least one of the electrodes of each sub-cell is formed together with the formation of the interconnect. 
   
   
       34 . The method of  claim 33 , wherein the first electrode of a first sub-cell of the plurality of sub-cells is formed together with the first and the second layers of the interconnect, and wherein the formation of the first electrode, the first layer and the second layer includes:
 i) disposing a second-layer material of the interconnect over the second electrode of a first sub-cell;   ii) disposing a first-layer material of the interconnect over the second-layer material;   iii) disposing a first-electrode material of a second sub-cell over the first-layer of the interconnect; and   iv) heating the materials such that the first-layer and second-layer materials of the interconnect form the first and second layers of the interconnect, respectively, and that the first-electrode material forms the first electrode.