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CN-122025686-A - Cr poisoning-resistant composite current collector for solid oxide fuel cell, and preparation method and application thereof

CN122025686ACN 122025686 ACN122025686 ACN 122025686ACN-122025686-A

Abstract

The invention belongs to the technical field of electrochemical materials, and particularly relates to a Cr-poisoning-resistant composite current collector layer for a solid oxide fuel cell, and a preparation method and application thereof. The Cr poisoning resistant composite current collector layer is a composite current collector layer constructed by adopting two perovskite materials LCN and LSCN, and the problem of cathode failure caused by volatilization of Cr of a metal connector is successfully solved by combining the physical barrier property of strontium-free LCN and the chemical capture property of strontium-containing LSCN. Aiming at the SOFC system using the iron-based alloy as the connector, the invention aims to solve the technical problem that the catalytic activity of the cathode is attenuated due to the volatilized chromium species of the metal connector in the high-temperature oxygen-enriched environment, thereby remarkably improving the long-term operation stability and the service life of the cell stack. According to the invention, through specific material combination and layered structure design, the contradiction that a single current collector layer is difficult to consider between blocking Cr volatilization and maintaining low contact resistance is solved, and the polarization impedance growth rate of the battery is obviously reduced.

Inventors

  • LI JUN
  • Yu Hezhan
  • LU XINYANG
  • Zhan Huanghao
  • ZHAO KAI
  • CHEN MIN

Assignees

  • 佛山大学

Dates

Publication Date
20260512
Application Date
20260123

Claims (10)

  1. 1. A Cr poisoning resistant composite current collector for a solid oxide fuel cell, the composite current collector comprising at least two layers of conductive ceramic material having a perovskite structure; The conductive ceramic material with the perovskite structure comprises an LCN material or LSCN material; the chemical general formula of the LCN material is LaCo 1-x Ni x O 3-δ , wherein x is more than or equal to 0.3 and less than or equal to 0.5; the chemical general formula of the LSCN material is La 1-y Sr y Co 1-z Ni z O 3-δ , wherein y is more than or equal to 0.1 and less than or equal to 0.3, and z is more than or equal to 0.3 and less than or equal to 0.5.
  2. 2. A method of preparing the Cr poisoning resistant composite current collector layer for a solid oxide fuel cell according to claim 1, comprising the steps of: 1) Dissolving hydrated metal nitrate in a sol aqueous solution, heating, gradually changing the color from pink to deep purple to obtain a gel precursor with viscoelasticity, drying and grinding the gel precursor into powder, and sintering the powder at high temperature to obtain pure-phase perovskite powder; the pure-phase perovskite powder comprises LCN or LSCN powder; In the preparation of the LCN powder, the adopted hydrated metal nitrate comprises La (NO 3 ) 3 ·6H 2 O、Co(NO 3 ) 2 ·6H 2 O and Ni (NO 3 ) 2 ·6H 2 O), wherein the mixing proportion of the La, the Co and the Ni=1 (1-x) is x, wherein x is more than or equal to 0.3 and less than or equal to 0.5, and the chemical general formula of the obtained LCN is LaCo 1-x Ni x O 3-δ ; In the preparation of LSCN powder, the adopted hydrated metal nitrate comprises La(NO 3 ) 3 ·6H 2 O、Sr(NO 3 ) 2 、Co(NO 3 ) 2 ·6H 2 O and Ni (NO 3 ) 2 ·6H 2 O), the mixing proportion of which is La 1-y Sr y Co 1-z Ni z O 3-δ according to the stoichiometric ratio of La to Sr to Co to Ni= (1-y) to y (1-z) to z, wherein y is more than or equal to 0.1 and less than or equal to 0.3, and z is more than or equal to 0.3 and less than or equal to 0.5, and the chemical formula of the obtained LSCN is La 1-y Sr y Co 1-z Ni z O 3-δ ; 2) The preparation of the Cr-poisoning-resistant composite current collector comprises the steps of firstly coating a layer LSCN of slurry on the surface of a cathode of a solid oxide fuel cell, drying, then coating a layer of LCN slurry, and drying to form a double-layer structure, thus obtaining the Cr-poisoning-resistant composite current collector.
  3. 3. The method for preparing the Cr poisoning resistant composite current collector layer according to claim 2, wherein the sol aqueous solution comprises a PVA aqueous solution prepared by adding PVA particles into deionized water, and heating and dissolving to obtain a PVA aqueous solution with a mass fraction of 2-10%.
  4. 4. The method for preparing the Cr poisoning resistant composite current collector according to claim 2, wherein the ratio of the total mole number of metal ions to the mole number of PVA monomer units after the hydrated metal nitrate is dissolved in the aqueous sol is 1 (1-5).
  5. 5. The method for preparing the Cr poisoning resistant composite current collector layer according to claim 2, wherein the mixture of water metal nitrate in the LCN powder is LaCo 0.6 Ni 0.4 O 3-δ according to a stoichiometric ratio La: co: ni=1:0.6:0.4.
  6. 6. The method for preparing the Cr poisoning resistant composite current collector according to claim 2, wherein the water metal nitrate in LSCN powder is mixed according to a stoichiometric ratio La: sr: co: ni=0.8:0.2:0.6:0.4, namely La 0.8 Sr 0.2 Co 0.6 Ni 0.4 O 3-δ .
  7. 7. The method for preparing the Cr poisoning resistant composite current collector layer according to claim 2, wherein the LSCN slurry or the LCN slurry is prepared by mixing LSCN powder or LCN powder with an organic binder, respectively, and the solid content of the LSCN powder or LCN powder is 30-60 wt%. The organic binder comprises ethyl cellulose terpineol solution or polyvinyl alcohol aqueous solution.
  8. 8. The method for preparing the Cr poisoning resistant composite current collector layer according to claim 2, wherein the high-temperature calcination temperature is 500-800 ℃ and the time is 3-5 hours.
  9. 9. Use of the Cr poisoning resistant composite current collector layer according to claim 1 for preparing a solid oxide fuel cell, wherein the solid oxide fuel cell is composed of a half cell, LSCN layers, an LCN layer, and a metal connector in order; the half cell comprises an electrolyte and a cathode, wherein the cathode is connected with LSCN layers; The cathode comprises a compound consisting of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and Gd 0.1 Ce 0.9 O 1.95 ; The electrolyte material comprises Gd 0.1 Ce 0.9 O 1.95 (GDC) or Yttria Stabilized Zirconia (YSZ); the material of the metal connector comprises Fe-Cr-based ferrite stainless steel.
  10. 10. Use of the La 0.8 Sr 0.2 Co 0.6 Ni 0.4 O 3-δ material according to claim 6 as a cathodic Cr-capture agent.

Description

Cr poisoning-resistant composite current collector for solid oxide fuel cell, and preparation method and application thereof Technical Field The invention belongs to the technical field of electrochemical materials, and particularly relates to a Cr-poisoning-resistant composite current collector layer for a solid oxide fuel cell, and a preparation method and application thereof. Background In many new energy technologies, the fuel cell is used as a device for converting chemical energy in fuel into electric energy directly through electrochemical reaction, and has the remarkable advantages of high energy conversion efficiency, environmental friendliness, strong modularization and the like because the fuel cell is not limited by the efficiency of a carnot cycle heat engine. The solid oxide fuel cell is used as a third generation fuel cell technology, and adopts an all-solid-state ceramic structure, so that the problems of corrosion and leakage of liquid electrolyte are avoided. SOFCs are typically operated at high temperatures of 600 ℃ to 1000 ℃, which gives them extremely high fuel flexibility and high quality waste heat utilization value. Therefore, the SOFC is recognized as a green power generation technology with great application prospect, and is widely applied to the fields of fixed power stations, distributed cogeneration systems, transportation auxiliary power sources, military power sources and the like. The output voltage of the single SOFC is usually only about 1V, and cannot meet the high voltage and high power requirements of practical applications. Therefore, in practical applications, a plurality of single cells are typically assembled in series into a cell stack through a "connector". The main functions of the connection body include physically connecting the anode and cathode of adjacent single cells, collecting and conducting current, and spatially separating the fuel gas on the anode side from the oxidant gas on the cathode side. As SOFC technology evolves toward medium temperature (600-800 ℃) traditional ceramic connectors are gradually replaced by metallic connectors due to processing difficulties, high cost and large brittleness. Iron-based alloys have become the dominant material for IT-SOFC connectors due to their excellent electronic conductivity, good thermal conductivity, low raw material costs, and well-established processing techniques. In order to protect the substrate from rapid oxidation corrosion under high temperature oxidizing atmospheres, these alloys must contain a sufficient amount of chromium element to form a dense chromium oxide protective film on the surface. However, it is this Cr 2O3 protective film that initiates one of the most troublesome failure mechanisms in SOFC technology—the cathodic Cr poisoning effect. In order to inhibit Cr volatilization and poisoning, the current mainstream strategy is to prepare a conductive ceramic coating on the surface of a metal connector. Common coating materials include spinels and perovskite, wherein the spinels coating can effectively reduce Cr volatilization, but the spinels coating has poor thermal expansion coefficient and certain connectors, is easy to fall off after long-term thermal cycling, and has higher preparation process cost, and the perovskite coating has higher conductivity. However, a single component perovskite coating suffers from the dilemma that if Sr is included, it is conductive but reacts with Cr to form a high-resistance layer, and if Sr is not included, the contact resistance with the cathode is large and the volatilized trace Cr cannot be actively adsorbed. Therefore, developing a low-cost composite current collector layer that has high conductivity, excellent barrier capability and can actively capture Cr species is a key to solve the problem of Cr poisoning of the SOFC cathode. Disclosure of Invention In view of the above problems, the present invention aims to provide a Cr poisoning resistant composite current collector layer for a solid oxide fuel cell, and a preparation method and application thereof. The technical content of the invention is as follows: The invention provides a Cr poisoning resistant composite current collecting layer for a solid oxide fuel cell, which is arranged between a cathode of the solid oxide fuel cell and a metal connector and aims at blocking volatilization of chromium element in the metal connector and diffusion of the chromium element to the cathode side; the composite current collecting layer comprises at least two layers of conductive ceramic materials with perovskite structures; The conductive ceramic material with the perovskite structure comprises an LCN material or LSCN material; The chemical general formula of the LCN material is LaCo 1-xNixO3-δ, preferably LaCo 0.6Ni0.4O3-δ, which is a strontium-free perovskite oxide, and does not contain alkaline earth metal Sr, so that the surface Sr segregation is not generated at high temperature, the chemical inertness to