JP2008503058A - Hardware on the cathode side of carbonate fuel cell - Google Patents

Abstract

In the perovskite structure AMEO _3, and lanthanum A is at least one of a combination of lanthanum and strontium, the perovskite structure AMEO ₃ Me is one or more transition metals, lithiated NiO (Li _x A conductive ceramic comprising one of NiO, where x is between 0.1 and 1 and LiNiO ₂ doped with X (where X is one of Mg, Ca and Co). FIG. 3 is a cathode side hardware of a carbonate fuel cell having a thin film coating. FIG.

Description

  The present invention relates to a molten carbonate fuel cell, and more particularly to cathode-side hardware used in a molten carbonate fuel cell.

  As used herein, the term “cathode side hardware” is defined as the cathode side current collector and / or bipolar plate of a fuel cell, particularly a molten carbonate fuel cell. Corrosion is a factor that limits the life of molten carbonate fuel cells. Extensive corrosion occurs at the interface with the oxidizing gas (or liquid), that is, on the cathode side hardware. This hardware is usually formed from chromium, including stainless steel, and the corrosion of the hardware is governed by outward cation diffusion through the metal vacancies. It is estimated that 25% of the internal resistance of the molten carbonate fuel cell is due to an oxide corrosion layer formed on the cathode side hardware.

  In particular, cathode current collectors, usually made of 316L stainless steel, are corroded during fuel cell operation, and many layers of corrosive oxides having a fairly high electrical resistance are formed on the collector surface. Furthermore, the formed corrosion layer usually becomes thicker with time.

  Furthermore, the corrosion layer on the cathode side hardware causes electrolyte loss and corrosion creep through the surface. The creep of the electrolyte surface is governed by capillary forces governed by the surface roughness, porosity, and pore size in the corroded layer. Electrolytic corrosion creep is governed by the scale thickness and phase composition of the scale formed. In cathode-side hardware formed of stainless steel, the large roughness of the scale surface and the porous structure of the scale cause large electrolyte surface creep.

  It was estimated that molten carbonate fuel cell electrolyte loss is an important lifetime limiting factor to achieve a lifetime of 40,000 hours. Analysis of the cathode hardware shows that 65% of the electrolyte loss is attributed to this hardware. It has been estimated that reducing electrolyte loss to 45% can result in a life extension of the molten carbonate fuel cell of about 1.7 years.

  In order to combat corrosion of the cathode side hardware, it has been proposed to provide a protective oxide coating on the cathode side hardware to reduce contact resistance and reduce electrolyte loss. However, these coatings must satisfy the stringent condition that on the one hand the coating must have high corrosion resistance and on the other hand the coating must have high electrical conductivity. The coating must also be able to provide a stable surface oxide that can provide a barrier between the molten carbonate fuel cell coating alloy and the environment.

  US Pat. No. 5,643,690 discloses a non-stoichiometric composite oxide formed by oxidation in a fuel cell of a layer of Fe, Ni and Cr coated on a cathode current collector. This type of coating in the form of a layer is disclosed. Similarly, Japanese Patent No. 5-324460 discloses a stainless steel collector plate coated with a NiO layer (formed by oxidation of a coated or plated Ni layer on a cathode current collector). . The coating formed in these cases is porous and consumes a significant amount of electrolyte. Also, the electrical conductivity of the layer may not be as high as desired.

US Patent Application Publication No. 2002/0164522, the same assignee as the present application, discloses another coating layer formed as a conductive layer of ceramic material using a sol-gel process. In this case, the material used for the conductive layer is preferably LiCoO ₂ or LiFeO ₂ doped with Co, and the thickness of the layer ranges from 1 to 5 μm.

It has been found that the aforementioned conductive ceramic layer of US 2002/0164522 provides satisfactory cathode-side hardware corrosion resistance. However, the material is expensive and adds to the overall cost of the fuel cell. Furthermore, higher conductivity is desired. As a result, fuel cell designers continue to seek other coating materials that provide the desired corrosion resistance, are less expensive, and have higher conductivity.
US Pat. No. 5,643,690 JP-A-5-324460 US Patent Application Publication No. 2002/0164522

  Accordingly, it is an object of the present invention to provide cathode side hardware that does not suffer from the above disadvantages.

  It is a further object of the present invention to provide low cost cathode side hardware with high corrosion resistance and electrical conductivity.

The above and other objects, in a perovskite structure AMEO _3, and A is lanthanum, is at least one of a combination of lanthanum and strontium, the perovskite structure AMEO ₃ Me is one or more transition metals, Dense lithiated NiO (Li _x NiO, where x is 0.1 to 1) and X is one of Mg, Ca and Co, and X doped LiNiO ₂ This is accomplished by forming cathode side hardware with a thin film of conductive ceramic coating.

  Preferably the coating is realized using a sol-gel process.

  These and other features and aspects of the present invention will become more apparent upon reading the following detailed description in conjunction with the accompanying drawings.

  FIG. 1 schematically shows a fuel cell having a cathode 2 and an anode 3. Between the cathode 2 and the anode 3 is a matrix 4 containing an alkali carbonate electrolyte. Adjacent to the anode 3 is a wavy current collector 3a and a bipolar 3b. Adjacent to the cathode 2 is cathode-side hardware 5 having a wave-like current collector 5a and a bipolar plate 5b. As shown, the bipolar plates 3b and 5b are the same.

In accordance with the principles of the present invention, the cathode side hardware 5 of the fuel cell 1 of FIG. 1 is coated with a conductive ceramic to obtain a low electrical resistivity for low contact voltage loss. Further according to the present invention, a perovskite material having the general formula AMeO ₃ , wherein A is at least one of lanthanum and a combination of lanthanum and strontium, and Me is a transition metal, and a cathode material, The use of lithiated NiO (Li _x NiO, where x is 0.1 to 1), previously proposed for use, is used herein as a coating material for cathode side hardware. The Further in accordance with the present invention, X-doped LiNiO ₂ material can be used as a cathode-side hardware coating material, where X is one of Mg, Ca and Co. The transition metal is shown as Me in AMeO _{3 and} is, but not limited to, Co, Fe, Cr, Mn and mixtures thereof. Perovskite materials include, but are not limited to, LSC (La _x Sr _x-1 CoO ₃ and especially La _0.8 Sr _0.2 CoO ₃ ), LaMnO ₃ , LaCoO ₃ , LaCrO ₃ and LSCF (La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ) Including. Examples of X-doped LiNiO ₂ materials include Mg-doped LiNiO ₂ , Ca-doped LiNiO ₂ and Co-doped LiNiO ₂ . These materials are lithiated with low solubility in alkali molten carbonate (eg 2 μg / cm ² / h for lithiated NiO) and very high electrical conductivity (600 S / cm at 600 ° C. for LSC). NiO has 33 S / cm at 650 ° C., LiNiO ₂ doped with Mg has 26 S / cm, and LiNiO ₂ doped with Co has 15 S / cm at 650 ° C.).

  These materials can be coated on the cathode side hardware using various coating techniques. In the present exemplary case, a thin film sol-gel coating process was used. This process involves the dissolution of a precursor containing the metal ions required in a suitable solvent to form a sol. The sol is then coated on the hardware surface by spraying or dipping, subsequently gelled, dried and subsequently densified and crystallized.

  Generally, drying is performed at a temperature between room temperature and 200 ° C. Usually, the densification and recrystallization process is performed at a temperature of 350 ° C. or higher. The surface of the metal substrate may require degreasing and acid cleaning to remove surface splashes and oxides for better coating adhesion. A coating coverage of 100% is not necessary for carbonate fuel cell applications in terms of ohmic contact resistance, but the surface is improved by ceramic coatings to achieve the desired benefits for improved corrosion protection and reduced electrolytes. It is preferable to have a coverage of more than 95%. As a result, the resulting cathode-side hardware can be provided with the required combination of structure and phase to provide the necessary properties.

Precursors for perovskite materials, lithiated NiO (Li _x NiO, where x is 0.1 to 1) and X doped LiNiO ₂ materials are inorganic salts such as acetates or nitrates Or it can be a hydroxide. The solution can be a water-soluble group or a solvent group. The substrate or substrate member of the cathode side hardware can be stainless steel.

  By appropriately controlling the processing parameters, coating techniques, heat treatment (in the case of sol-gel), densification and uniform and smooth thin film coating are obtained. The primary corrosion resistance of the dense oxide coated cathode side hardware of the present invention is governed by transport through the intentionally coated dense oxide layer. The dense oxide coating significantly delays the attack of carbonate ions that migrate to the underlying hardware substrate (eg, a stainless steel substrate).

  In particular, the main effect of the formed oxide layer is to provide a barrier to the contact between the hardware substrate and gas and liquid. On the other hand, the contact resistance between the hardware substrate and the cathode electrode is also reduced compared to having a corrosion scale formed on the uncoated hardware due to the highly conductive corrosion resistant oxide layer. The electrical resistance is reduced by 50% compared to an uncoated hardware substrate made of chromium steel, as shown from fuel cell tests.

Furthermore, both the surface roughness and corrosion are minimized by the dense and smooth surface coated with the perovskite material of the cathode side hardware, lithiated NiO and X doped LiNiO ₂ of the present invention. Thus, electrolyte surface and corrosion creep are also minimized.

  Also, the cathode side hardware coating was found to exhibit good adhesion, well matched thermal expansion coefficient, effective electrical conductivity, and protection against thermal oxidation / corrosion. Accelerated thermal cycling tests on the coating showed that the coating was thin and very adherent. Good adhesion results from the structure bonded by the reaction between the hardware substrate and the coating and the properties of the thin film (tensile stress is proportional to coating thickness). Also, matching of bulk properties over the harsh temperature and chemical potential range of fuel cells has been achieved.

As described above, the coatings of the present invention (Li _0.1 NiO ₂ , perovskite materials, and X-doped LiNiO ₂ ) are also quite highly conductive (eg, 33 S / cm for Li _0.1 NiO ₂ , LSC) 650 S / cm for Co, and 15 S / cm at 650 ° C. for Co-doped LiNiO ₂ ), and more importantly, the LiCoO ₂ coating (conductivity of 1 S / cm) of US patent application 2002/0164522 When compared, it is a dense and smooth film with a controlled coating thickness.

  The following are examples relating to the invention.

Example 1 Lithiumated cathode side hardware (1) Preparation of lithiated NiO sol-gel Using reagent grade Li acetate and Ni acetate as the cation source compound, nominal Li: Ni A starting solution having a composition of 0.1: 1 (molar ratio) was prepared. The appropriate amount of these materials to be included in the starting solution was then calculated based on obtaining a 1M NiO sol-gel. The measured amount of cation source compound was then mixed in a 600 ml beaker with 200 ml distilled water, 300 ml ethylene glycol and 1.5 mol citric acid to form a precipitate-free starting solution. The starting solution was concentrated until the starting solution was heated on a hot plate at about 80 ° C. to turn into a viscous liquid. A green and clear solution resulted. This solution was allowed to remain unchanged in a sealed glass beaker at 25 ° C. without sedimentation for at least half a year. The change in viscosity of the solution due to polymerization was measured at room temperature with a Brookfield viscometer. The viscosity of the precursor increases significantly with increasing heating time due to the increase in average molecular weight as a result of polymerization.

(2) Cathode side hardware deposition and formation with a dense and smooth lithiated NiO film The dip coating technique uses a corrugated stainless steel (316L) sheet or precursor on a substrate used as a cathode side substrate. Used to form a wet film. Film thickness was achieved by controlling the draw rate and viscosity of the precursor. In general, a precursor having a viscosity of 125 cP or less at room temperature cannot uniformly wet a smooth substrate such as stainless steel. On the other hand, the highly viscous precursor having a viscosity of about 1000 cP or more at room temperature, when the substrate was not heated at a high temperature, became a non-uniform film and formed cracks in the film. Therefore, it is important to control the viscosity of the solution in order to obtain a high quality film. The viscosity of the precursor solution was used in this example in the range of 200-275 cP at room temperature. Using a draw speed of 1 inch / minute, a dense, lithiated NiO oxide film having a thickness in the range of about 0.5 to about 1 μm for each coating after firing at about 600 ° C. was obtained. .

  In order to increase the wettability of the sol and increase the bond strength between the lithiated nickel oxide film and the stainless steel sheet, the sheet is formed first during acid treatment followed by heat treatment in a graphite furnace. Ultrasonic cleaning with acetone was used to remove possible dust and carbon films. The gel film was deposited on either a 1.5 inch x 1.5 inch or 7 inch x 7 inch corrugated cathode by dip coating at a substrate draw speed of 1 inch / minute. The substrate with the gel film is transferred to a furnace preheated to 70 ° C. immediately after the gel film deposition, heated to a temperature not exceeding 600 ° C. for a further 3 hours to fully crystallize and sinter, and held for 3 hours. It was done.

  After heating to 600 ° C., the membrane remained continuous, smooth and dense on the cathode side hardware substrate. Figures 2A and 2B show SEM photographs of the fractured surface of the film coated hardware at different magnifications. From these figures, it was found that a thin lithiated Ni oxide film having a substantially constant thickness of about 1 μm was realized.

(3) Characterization of the lithiated NiO film X-ray in which the phase evolution of the Li _0.1 NiO oxide film deposited on a stainless steel (316L) substrate was performed on a Philips diffractometer using Cu-Ka irradiation It was studied by diffraction analysis. The result is shown in FIG. The substrate heat-treated at 200 ° C. has no peak and shows an amorphous structure. The formation of rock salt NiO structure was observed as low as 350 ℃. However, there was a second phase formed at 350 ° C. and displayed as NiC. At high temperatures, NiC is oxidized to form NiO. Crystallization is complete at 450 ° C., there is no broad peak, and the peak intensity does not change above 450 ° C. With the exception of 200 ° C and 350 ° C, all coatings were single phase and no other secondary products or reactants were detected.

  As is apparent, lithiated NiO conforms to the NiO structure (rock salt structure) and the pattern can be indexed by the Bragg peak of NiO. There is no preferred position for lithium and nickel ions. Therefore, there is only one cation crystal. Partial replacement of nickel (II) (r = 0.83Å) with lithium (I) (r = 0.90Å) causes nickel (III) (r = 0) to shrink the lattice with a smaller ionic radius r. Implying formation of 70 Å Using higher processing temperature, phase shifts to a larger angle, implying more Li dissolution in the NiO structure (creating more Ni (III)) The peak narrows with increasing temperature, indicating crystallite size growth.

Example 2 Lan _0.8 Sr _0.2 CoO ₃ cathode side hardware
(1) Preparation of Lan _0.8 Sr _0.2 CoO ₃ sol-gel Using reagent grade La nitrate hydrate, Sr nitrate hydrate and Co nitrate hydrate, the nominal La: Sr: Co composition is 0 A starting solution of 8: 0.2: 1 (molar ratio) was prepared. The appropriate amount of these materials to be included in the starting solution was then calculated based on obtaining a 1M LSC sol-gel. The measured amount of cation source compound was then mixed in a 600 ml beaker with 150 ml distilled water, 350 ml ethylene glycol to form a precipitate-free starting solution. The starting solution was heated on a hot plate at about 80 ° C., draining water and other volatiles to form a viscous polymer precursor with a polymer containing metal cations. It is important that cations remain in solution throughout the polymerization process. The change in viscosity of the solution as it was converted to the polymer precursor was measured at room temperature with a Brookfield viscometer.

(2) Deposition and formation of cathode-side hardware with smooth and dense LSC film To increase sol wettability and bond strength between LSC film and stainless steel (316L) cathode-side hardware Stainless steel was first acid treated, followed by ultrasonic cleaning with acetone to remove dust and carbon films that might form during heat treatment in the graphite furnace. Gel films were deposited on either 1.5 inch x 1.5 inch or 7 inch x 7 inch corrugated cathodes by dip coating at a substrate draw rate of 1 inch / minute. The gel film was transferred to a furnace preheated to 70 ° C. immediately after gel film deposition, heated to a temperature not exceeding 600 ° C. for a further 3 hours and fully held for 3 hours to fully crystallize and sinter.

  After heating to 600 ° C., the membrane remained continuous, smooth and dense on the cathode side hardware substrate. FIG. 3 is an SEM photograph showing the morphology of the hardware surface coated with LSC.

  The effect of thermal cycling on the integrity of cathode side hardware sheets coated with lithiated NiO and LSC was evaluated. Examination of the specimen after thermal cycling with an optical microscope and SEM reveals that the coating can coexist thermally with a hardware substrate or substrate without cracks or microcracks introduced by thermal stress. Became.

  FIGS. 5A-5D show an SEM observation of a cut surface of an exemplary embodiment of cathode side hardware coated with a lithiated NiO conductive coating according to the present invention compared to uncoated cathode side hardware in FIGS. Indicated. As can be seen, the lithiated NiO coating of the present invention (FIGS. 5A and 5B) has a reduced corrosion scale thickness when compared to uncoated cathode side hardware (FIGS. 5C and 5D). is doing. Furthermore, the corrosion scale shows a similar double layer structure regardless of the sol-gel coating. However, for coated hardware, the outer oxide scale can be finer to better protect the inner Cr-rich scale. As a result, the Cr-rich inner scale of the coated sheet was more dense and more protective to reduce the overall corrosion rate.

  FIG. 6A shows the out-of-cell electrical resistivity of the cathode-side hardware cathode in a current collector (“CCC”) configuration with lithiated NiO and LSC coatings of the present invention. FIG. 6A also shows the electrical resistivity outside the cell of an uncoated stainless steel current collector cell. As is apparent from the figure, the coated CCC of the present invention has an out-of-cell resistivity comparable to the uncoated CCC. Furthermore, as is apparent from FIG. 6B, the electrical resistivity (metal to metal) of the coated CCC of the present invention from an out-of cell current collector is also the CCC of the stainless steel uncoated from the current collector. Comparable to the electrical resistivity.

  FIGS. 7 and 8 compare the resistance life graphs of fuel cells using CCC coated with the lithiated NiO and LSC coatings of the present invention, respectively, with fuel cells using uncoated stainless steel CCC. It shows. As can be seen from these graphs, improved resistance life has been achieved for fuel cells using CCC with the coating of the present invention.

  FIG. 9 shows the corrosion thickness after a fuel cell test of a coated CCC of the present invention compared to the corrosion thickness after a fuel cell test of an uncoated CCC. It can be seen that the coated CCC of the present invention exhibits less measurable corrosion than the uncoated CCC.

  Finally, FIG. 10 shows the loss of electrolyte in a molten carbonate fuel cell using CCC coated with the coating membrane of the present invention compared to a molten carbonate fuel cell using uncoated CCC. . As is apparent from the figure, the electrolyte loss is much less in fuel cells using the coating of the present invention.

Example 3 LSCF (Lan _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ) cathode side hardware
(1) Preparation of LSCF (Lan _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ) Sol-Gel Using analytical grade La acetate, Sr acetate, Co acetate, Fe acetate, nominal La: Sr A starting solution having a Co: Fe composition of 0.8: 0.2: 0.8: 0.2 (molar ratio) was prepared. The appropriate amount of these materials to be included in the starting solution was then calculated based on obtaining 1M LSCF sol-gel. The measured amount of cation source compound was then mixed in a 1000 ml beaker with 2150 ml distilled water, 350 ml ethylene glycol to form a starting solution. The starting solution was heated on a hot plate at about 65 ° C. and stirred for 48 hours at 65 ° C., draining water and other volatile materials to form a viscous polymer containing metal cations. During the formation of this viscous polymer, it is important not to overheat the solution as this is done in an exothermic process. After finishing heating the solution, the viscosity change of the solution as it was converted to the polymer precursor was measured at room temperature with a Brookfield viscometer.

(2) Cathode-side hardware deposition and formation with a smooth and dense LSCF (Lan _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ) film The LSCF film uses a dip coating as described above in Example 2. Deposited on the cathode side hardware. The LSCF film deposited on the cathode side hardware substrate is a continuous smooth and dense film. FIG. 11 is a SEM photograph showing the surface morphology of the cathode-side hardware coated with LSCF. Similar to the LSC-coated cathode hardware shown in FIG. 3, the SEM shown in FIG. 11 allows the LSCF coating to thermally match the hardware substrate or substrate and detect cracks introduced by thermal pressure. It became clear that not.

Example 4 Mg-doped LiNiO ₂ cathode side hardware
(1) Preparation of Mg-doped LiNiO ₂ sol-gel Reagent grade Mg acetate, Li acetate (Li- (CH ₃ COO)), hydrated Ni nitrate (Ni- (CH ₃ COO) ₂ ) And citric acid were used to prepare a starting solution in which the Mg: Lir: Ni: citric acid composition had a molar ratio of 0.1: 0.9: 1: 2. The appropriate amounts of these materials to be included in the starting solution were then calculated based on obtaining 1M Mg doped LiNiO ₂ sol-gel. Next, measured amounts of cation source compounds, ie, Mg acetate, Li acetate and hydrated Ni nitrate, were mixed in a 1000 ml beaker with 400 ml distilled water, 2 moles citric acid and started. The solution was heated to about 80 ° C. and stirred with a magnetic stir bar to form a clean starting solution without sediment. Water and other volatile materials were discharged to form a viscous polymer precursor with a polymer containing metal cations. It is important that cations remain in solution throughout the polymerization process. The change in the viscosity of the solution as it was converted to the polymer precursor was measured at room temperature with a Brookfield viscometer. After the solution reached the desired concentration, heating was terminated and the viscosity of the solution was measured. The change in viscosity of the solution as it converted to a viscous solution was measured at room temperature by a Brookfield viscometer. These measurements showed that the viscosity of the solution increased significantly with increasing heating time due to the increase in average molecular weight as a result of polymerization. Thus, this viscous solution was allowed to remain undisturbed at 25 ° C. in a sealed glass beaker for at least half a year.

(2) Deposition and formation of cathode-side hardware with smooth and dense Mg-doped LiNiO ₂ film
A Mg-doped LiNiO ₂ film was deposited on the cathode side hardware using a dip coating as described above in Example 2. FIG. 12 is an SEM photograph showing the surface morphology when 316L cathode-side hardware is coated with Mg-doped LiNiO ₂ . Similar to FIGS. 3 and 11, the Mg-doped LiNiO ₂ coating on the cathode side hardware is smooth and dense and this coating is introduced by thermal pressure to thermally match the hardware or substrate. It became clear that no cracks were detected.

Example 5 Co-doped LiNiO ₂ cathode side hardware (1) Preparation of Co-doped LiNiO ₂ sol-gel Reagent grade Co acetate, Li acetate (Li- (CH ₃ COO)), hydrated Using Ni nitrate (Ni- (CH ₃ COO) ₂ ) and citric acid, the Co: Lir: Ni: citric acid composition has a molar ratio of 0.1: 0.9: 1: 2 A solution was prepared. The appropriate amount of these materials to be included in the starting solution was then calculated based on obtaining 1M Co doped LiNiO ₂ sol-gel. The measured amount of cation source compound is then mixed in a 1000 ml beaker with 400 ml distilled water, 2 moles citric acid, and the starting solution is heated to about 80 ° C. and stirred using a magnetic stir bar. To form a clean starting solution without sediment. The starting solution drained water and other volatiles when heated to about 80 ° C., forming a green clear viscous solution. The change in viscosity of the solution as it was converted to a viscous solution was measured at room temperature with a Brookfield viscometer. As in the previous examples, the viscosity of the solution increased significantly with increasing heating time due to the increase in average molecular weight as a result of the polymerization. Thus, this viscous solution was allowed to remain undisturbed at 25 ° C. in a sealed glass beaker for at least half a year.

(2) Deposition and formation of cathode-side hardware with smooth and dense Co-doped LiNiO ₂ film
A Co-doped LiNiO ₂ film was deposited on the cathode side hardware using a dip coating as described above in Example 2. FIG. 13 is an SEM photograph showing the surface morphology when 316L cathode-side hardware is coated with Co-doped LiNiO ₂ . Similar to FIGS. 3, 11 and 12, the Co-doped LiNiO ₂ coating on the cathode side hardware substrate was a continuous, smooth and dense film. Cracks introduced into the coating by thermal pressure were not detected.

  In all cases, it will be appreciated that the arrangements described above are merely illustrative using a number of possible specific embodiments illustrating the application of the present invention. Many variations of other configurations based on the principles of the invention may be readily derived without departing from the spirit and scope of the invention.

1 is a diagram schematically illustrating a fuel cell including cathode-side hardware based on the principle of the present invention. FIG. , FIG. 3 shows SEM micrographs at different magnifications of a conductive lithiated NiO coating on cathode side hardware in accordance with the principles of the present invention. FIG. 3 is a view showing a conductive LSC-coated SEM micrograph of cathode-side hardware based on the principles of the present invention. FIG. 3 is a diagram showing the phase evolution of a lithiated NiO coating of the type shown in FIG. 2A and FIG. , , , FIG. 2 shows the effect of immersion erosion tests on both cathode side hardware coated with a lithiated NiO conductive coating and uncoated cathode side hardware according to the present invention. , FIG. 4 shows the electrical resistance from the cell of the lithiated NiO coating and LSC coated cathode side hardware and the uncoated cathode side hardware and metal-metal electrical resistance according to the present invention. , FIG. 4 is a graph of resistance life testing of a molten carbonate fuel cell having cathode-side hardware with lithiated NiO and LSC conductive ceramic coatings of the present invention. FIG. 6 is a diagram comparing the corrosion thickness after fuel cell testing of cathode side hardware using the conductive ceramic coating of the present invention with the corrosion thickness after fuel cell testing using uncoated cathode side hardware. FIG. 4 compares loss in molten carbonate fuel cell test using cathode side hardware with conductive ceramic coating of the present invention with loss in molten carbonate fuel cell using uncoated cathode side hardware. . FIG. 3 is a SEM micrograph of a conductive LSCF coating on cathode side hardware based on the principles of the present invention. FIG. 3 is a SEM micrograph of a LiNiO ₂ coating doped with conductive Mg for cathode-side hardware based on the principles of the present invention. Conductive Co of the cathode-side hardware in accordance with the principles of the present invention is an SEM micrograph of doped LiNiO ₂ coating.

Claims (24)

A perovskite structure AMeO ₃ in which A is at least one of lanthanum and a combination of lanthanum and strontium, and Me is one or more transition metals;
Lithiated NiO (Li _x NiO, where x is 0.1 to 1);
X is one of Mg, Ca and Co, LiNiO ₂ doped with X,
A cathode current collector for a carbonate fuel cell, characterized in that it has a thin film coating of conductive ceramic containing one of the following.   The cathode current collector of a carbonate fuel cell according to claim 1, wherein the thin film coating is obtained by a sol-gel process.   The cathode current collector of a carbonate fuel cell according to claim 2, wherein the thickness of the thin film coating is in the range of 0.5 µm to 5 µm. The perovskite structure AMeO ₃ is one of LSC (La _x Sr _x-1 CoO ₃ ), LaMnO ₃ , LaCoO ₃ , LaCrO ₃ and LSCF (La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ). The cathode current collector of a carbonate fuel cell according to claim 3. A perovskite structure AMeO ₃ in which A is at least one of lanthanum and a combination of lanthanum and strontium, and Me is one or more transition metals;
Lithiated NiO (Li _x NiO, where x is 0.1 to 1);
X is one of Mg, Ca and Co, LiNiO ₂ doped with X,
A bipolar plate for a cathode of a carbonate fuel cell, characterized in that it has a thin film coating of conductive ceramic containing one of the following.   The bipolar plate for a cathode of a carbonate fuel cell according to claim 5, wherein the thin film coating is obtained by a sol-gel process.   The bipolar plate for a cathode of a carbonate fuel cell according to claim 6, wherein the thickness of the thin film coating is in the range of 0.5 µm to 5 µm. The perovskite structure AMeO ₃ is one of LSC (La _x Sr _x-1 CoO ₃ ), LaMnO ₃ , LaCoO ₃ , LaCrO ₃ and LSCF (La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ). The bipolar plate for a cathode of a carbonate fuel cell according to claim 7, A cathode,
An anode,
A matrix for storing a carbonate electrolyte disposed between the anode and the cathode;
A cathode current collector disposed adjacent to the cathode;
A bipolar plate disposed adjacent to the cathode current collector;
Have
At least one of the cathode current collector and the bipolar plate is
A perovskite structure AMeO ₃ in which A is at least one of lanthanum and a combination of lanthanum and strontium, and Me is one or more transition metals;
Lithiated NiO (Li _x NiO, where x is 0.1 to 1);
X is one of Mg, Ca and Co, LiNiO ₂ doped with X,
A carbonate fuel cell comprising a thin film coating of a conductive ceramic comprising one of the following:   The carbonate fuel cell according to claim 9, wherein the thin film coating is obtained by a sol-gel process.   The carbonate fuel cell according to claim 10, wherein the thickness of the thin film coating is in the range of 0.5 μm to 5 μm. The perovskite structure AMeO ₃ is one of LSC (La _x Sr _x-1 CoO ₃ ), LaMnO ₃ , LaCoO ₃ , LaCrO ₃ and LSCF (La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ). The carbonate fuel cell according to claim 11, wherein Both the cathode current collector and the bipolar plate are
A perovskite structure AMeO _{3 in} which A is at least one of the combination of lanthanum and lanthanum and strontium, and Me is one or more transition metals;
Lithiated NiO (Li _x NiO, where x is 0.1 to 1);
LiNiO ₂ where X is one of Mg, Ca and Co, and X is doped;
10. A carbonate fuel cell according to claim 9 having a conductive ceramic thin film coating comprising one of them.   The carbonate fuel cell according to claim 13, wherein the thin film coating is obtained by a sol-gel process.   15. The carbonate fuel cell according to claim 14, wherein the thickness of the thin film coating is in the range of 0.5 μm to 5 μm. The perovskite structure AMeO ₃ is one of LSC (La _x Sr _x-1 CoO ₃ ), LaMnO ₃ , LaCoO ₃ , LaCrO ₃ and LSCF (La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ ). The carbonate fuel cell according to claim 15, characterized in that: A method of manufacturing a cathode current collector or bipolar plate of a carbonate fuel cell, comprising:
Preparing a viscous solution having a viscosity ranging from 125 cp to 1000 cp at room temperature and containing a lithium cation and a Ni cation and a viscous solution containing at least a La cation and a Me cation in which Me is a transition metal And a process of
Immersing the substrate in the viscous solution, lifting the substrate from the viscous solution to form a coating of the viscous solution on the substrate;
Heating the coated substrate after lifting from the viscous solution.   The method according to claim 17, wherein the viscosity of the viscous solution is in the range of 200 cp to 275 cp at room temperature.   The method according to claim 18, wherein the step of pulling up the substrate from the viscous solution is performed at a rate of 1 inch / minute, and the heating step is performed at a temperature of 600 ° C for 3 hours.   The manufacturing method according to claim 17, wherein the substrate includes stainless steel.   The manufacturing method according to claim 20, wherein the substrate is corrugated.   The manufacturing method according to claim 17, wherein the viscous solution contains a lithium cation and a Ni cation, and further contains one of an Mg cation, a Co cation, and a Ca cation.   The production method according to claim 17, wherein the viscous solution contains a La cation and a Me cation, and further contains a Sr cation.   The manufacturing method according to claim 23, wherein the Me is at least one of Co, Fe, Cr, and Mn.