A method for preparing a cathode for a solid oxide fuel cell using a positive electrode recovery material of a waste lithium battery

Abstract

The application belongs to the technical field of electrode material recycling and fuel cell, and more particularly relates to a method for preparing a cathode for a solid oxide fuel cell by using a positive electrode recycling material of a waste lithium battery. The method directly uses a semi-finished product complex produced by recycling a lithium battery positive electrode material as a raw material; by using the strong complexing ability of a eutectic system formed by a sugar and an amino compound, the dissolution of a difficult-to-dissolve recycling material and the atomic-level mixing of other metal salt raw materials are realized, so that an air electrode material with high performance is prepared. The air electrode material prepared from the lithium battery positive electrode recycling material has no impurity phase, the micro-morphology is a uniform nano structure, and has a smaller lattice constant. The material obtained by the application exhibits more excellent electrochemical performance than the same kind of material prepared by using a traditional raw material in an electrochemical test. Research shows that the impurity elements in the recycling product can significantly improve the electrochemical performance of the prepared air electrode material through a doping effect.

Description

Technical Field

[0001] This application belongs to the field of electrode material recycling and fuel cell technology, and more specifically, relates to a method for preparing a cathode for a solid oxide fuel cell using recycled materials from waste lithium battery cathodes. Background Technology

[0002] Lithium-ion batteries are widely used in many fields of production and daily life due to their unique advantages such as high energy density, high voltage, good cycle performance, low self-discharge, safe operation, and environmental friendliness. High demand has led to a year-on-year increase in lithium-ion battery production. However, because lithium-ion batteries have a limited lifespan, the amount of waste lithium-ion batteries generated is also increasing annually. Batteries are classified as heavily polluting solid waste and are a significant environmental pollutant, making the treatment and reuse of waste batteries imperative. Waste lithium batteries contain various metals such as nickel, cobalt, manganese, lithium, aluminum, and copper. Resource-based recycling and reuse of these valuable metals is of significant practical importance in alleviating the continuously growing demand pressure for related materials. Typically, when recovering valuable metals from the cathode materials of waste lithium batteries, these valuable metals are recycled separately from lithium to minimize the presence of lithium in the recovered valuable metals.

[0003] The cathode of a solid oxide fuel cell is typically exposed to air and is therefore often referred to as the air electrode. The key material used is called the cathode material. Methods for preparing air electrode materials generally include solid-state synthesis, co-precipitation, the Sol-Gel method, the glycine nitrate method, and electrospinning. Solid-state synthesis is favored due to its simplicity and cost-effectiveness; however, it requires high-temperature calcination (typically exceeding 1000°C), which hinders the acquisition of nanoscale powders and often results in high impurity content. The Sol-Gel and glycine nitrate methods can achieve uniform mixing of multiple elements and prepare nanoscale powders, but these processes use large amounts of solvents, severely limiting their applicability in industrial production. Electrospinning can prepare nanofiber materials with high specific surface area, but this method requires specialized equipment and has low yield, similarly limiting its feasibility in industrial applications. Furthermore, except for solid-state synthesis, the metal sources used in the above methods are generally high-purity soluble metal salts to avoid impurities adversely affecting product performance, resulting in high costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application discloses a method for preparing the air electrode of a solid oxide fuel cell at low temperatures using products recovered from spent lithium-ion battery cathode materials as raw materials. The method employs an anhydrous system and low-temperature activation sintering, which is beneficial for the recycling and reuse of waste resources. It also emphasizes energy conservation and environmental protection, with short processing time and low calcination temperature, making it highly suitable for industrial-scale production. This method has significant research and application value for both the lithium-ion battery cathode material recycling field and the solid oxide fuel cell manufacturing field.

[0005] To achieve the above objectives, in a first aspect, this application provides a method for preparing a cathode for a solid oxide fuel cell using recycled materials from spent lithium-ion battery cathodes, comprising the following steps: (1) Mix sugars and amino compounds and heat to form a transparent, homogeneous eutectic solvent; (2) Add lithium battery cathode recovery material and optional other metal salt materials to the eutectic solvent, heat and stir to obtain a black gel-like mixture; wherein the recovery material is a metal complex obtained by wet recovery of lithium battery cathode material through eutectic solvent, the metal complex contains at least one of nickel, cobalt and manganese complexes, and contains residual lithium; the other metal salt materials are used to provide other metal elements not contained in the recovery material and required for the air electrode material; (3) The black gel-like mixture is dried, ground and sintered to obtain an air electrode material for solid oxide fuel cells.

[0006] Preferably, the sugar is one or more of glucose, fructose, sucrose, maltose, starch, cellulose, ribose, and lactose.

[0007] Preferably, the amino compound is urea and / or ammonium nitrate.

[0008] Preferably, the recycled material is a metal complex obtained by wet recycling of lithium battery cathode material using a eutectic solvent. The main component of the complex is oxalate, which contains trace amounts of lithium impurities, with a mass fraction ≤0.5%.

[0009] More preferably, the recycling method of the recycled material includes the following steps: leaching the lithium nickel cobalt manganese oxide ternary cathode material in a eutectic solvent at 90-100℃ for 30-60 min and then performing solid-liquid separation; adding oxalic acid as a precipitant to the filtrate obtained from the solid-liquid separation; heating and stirring to cause cobalt to precipitate; after the reaction is completed, performing solid-liquid separation; washing and drying the separated precipitate to obtain the cobalt-containing complex recycled material. The preparation of the eutectic solvent is based on the hydrogen bonding between choline chloride as a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond donor is one or more of oxalic acid, malonic acid, tartaric acid, glutaric acid, malic acid, and succinic acid.

[0010] This invention provides a method for preparing an air electrode for a solid oxide fuel cell using recycled materials from spent lithium-ion battery cathodes. The method includes: first, heating and mixing sugars and amino compounds to prepare a eutectic solvent; adding metal salt materials obtained from the recycled spent lithium-ion battery cathodes and other raw materials to the prepared eutectic solvent and mixing thoroughly; and then performing drying, grinding, and sintering treatments to obtain the air electrode material for a solid oxide fuel cell. Overall, compared with existing technologies, the above-described technical solution has the following advantages: (1) This invention proposes for the first time a method for preparing the air electrode of solid oxide fuel cells (SOFCs) at low temperature using metal complexes recovered from waste lithium battery cathode materials as raw materials, which is beneficial to the recycling and reuse of waste resources.

[0011] (2) This invention reveals for the first time the positive promoting effect of trace impurities Li in the recovered semi-finished complex on the performance of air electrode materials for solid oxide batteries, achieving unexpected technical results.

[0012] (3) This invention does not require the use of expensive high-purity raw materials, and reduces production costs while ensuring or even improving performance. Attached Figure Description

[0013] Figure 1 A schematic diagram of X-ray diffraction (XRD) of the LSCF air electrode material of Embodiment 1 of the present invention is shown.

[0014] Figure 2 A schematic diagram of the surface-enhanced Raman spectroscopy (SERS) of the LSCF air electrode material of Embodiment 1 of the present invention is shown.

[0015] Figure 3 A schematic diagram of a scanning electron microscope (SEM) of the LSCF air electrode material of Embodiment 1 of the present invention is shown. Figure 3 The morphology results are shown at a scale of 100 nm.

[0016] Figure 4 The impedance performance test results of batteries prepared using the LSCF air electrode materials of Example 1 and Comparative Example 1 at different temperatures are shown in the figure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] This invention provides a method for preparing a cathode for a solid oxide fuel cell using recycled cathode materials from spent lithium batteries, comprising the following steps: (1) Mix sugars and amino compounds and heat to form a transparent, homogeneous eutectic solvent; (2) Add lithium battery cathode recovery material and optional other metal salt materials to the eutectic solvent, heat and stir to obtain a black gel-like mixture; wherein the recovery material is a metal complex obtained by wet recovery of lithium battery cathode material through eutectic solvent, the metal complex contains at least one of nickel, cobalt and manganese complexes, and contains residual lithium; the other metal salt materials are used to provide other metal elements not contained in the recovery material and required for the air electrode material; (3) The black gel-like mixture is dried, ground and sintered to obtain an air electrode material for solid oxide fuel cells.

[0019] This method, based on the self-propagating combustion of solution precursors and the template pore-forming effect, exhibits broad inclusiveness regarding the elemental composition of the target material at the synthesis level. Therefore, it is applicable to the preparation of most ABO3-type perovskite air electrode materials with transition metals (such as Mn, Fe, Co, Ni, etc.) as B-sites and alkaline earth / rare earth metals (such as Sr, La, Ba, etc.) as A-sites. These materials rely on high porosity and nanoscale uniformity to enhance oxygen reduction reaction activity, and the preparation method of this invention possesses inherent advantages in molecular-scale mixing and porous structure construction. The air electrode materials applicable to this method include, but are not limited to, LSC (La... 1-x Sr x CoO 3-δ ), SSC (Sm 1-x Sr x CoO 3-δ ), BSCF (Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ ), LSF (La 1-x Sr x FeO 3-δ ), LSCF (La 1-x Sr x Co 1-y Fe y O 3-δ LSM (La 1-x Sr x MnO 3±δ LSN (La2NiO) 4+δ LNF (LaNi) 1-x Fex O 3-δ )wait.

[0020] In some embodiments, the sugar is one or more of glucose, fructose, sucrose, maltose, starch, cellulose, ribose, and lactose. The amino compound is urea and / or ammonium nitrate.

[0021] In some embodiments, the lithium battery cathode recycling material of the present invention is a metal complex obtained by recovering lithium battery cathode material via a eutectic solvent wet process. The main component of the complex is oxalate, which contains trace amounts of lithium impurities, with a mass fraction ≤0.5%. The metal complex is one or more of nickel, cobalt, or manganese complexes.

[0022] In some embodiments, a lithium battery cathode material containing one or more of nickel, cobalt, and manganese is leached in a eutectic solvent at 90-100°C for 30-60 minutes, followed by solid-liquid separation. Oxalic acid is added to the filtrate obtained from the solid-liquid separation as a precipitant, and the mixture is heated and stirred to induce a cobalt precipitation reaction. After the reaction is completed, the solid and liquid components are separated, and the separated precipitate is washed and dried to obtain a cobalt-containing complex recovery material. The eutectic solvent is prepared based on the hydrogen bonding interaction between choline chloride (ChCl) as a hydrogen bond acceptor and a hydrogen bond donor. The hydrogen bond donor is one or more of oxalic acid (OA), malonic acid (MalA), tartaric acid, glutaric acid, malic acid, and succinic acid.

[0023] In some embodiments, the solid-liquid ratio of the lithium battery cathode material of the present invention during leaching in a eutectic solvent is (15-25) mg:(0.5-1.5) mL. The water content in the eutectic solvent is 10-35 wt%; when oxalic acid is used for precipitation, the concentration of oxalic acid is 0.1-0.3 mol / L, the volume ratio of filtrate to oxalic acid solution is 1:(2-4), and the precipitation reaction is carried out by stirring at 75-85℃ for 30-90 min.

[0024] In some embodiments, the eutectic solvent is prepared by simply mixing the hydrogen bond donor and the hydrogen bond acceptor in a round-bottom flask at a molar ratio of (1.5-2.5):1 and stirring at 50-70°C for 1.5-2.5 hours until a homogeneous and transparent liquid is formed. Subsequently, 10-35 wt% water is added as a diluent to reduce the viscosity of the system. After the reaction is complete, the liquid is allowed to cool naturally to room temperature to obtain the eutectic solvent for use.

[0025] This invention relates to the recovery of materials required for the preparation of cathodes for solid oxide fuel cells. The recovery method is based on the method for separating and recovering nickel, cobalt, and manganese from lithium-ion battery cathode materials as described in EnergyStorage Materials 82 (2025) 104585. This method utilizes the unique coordination chemistry of water-controlled deep eutectic solvents to strategically control the water content in a choline chloride-malonic acid deep eutectic solvent system, achieving a nickel / cobalt separation coefficient as high as 125. This allows for the sequential recovery of nickel, cobalt, and manganese with purities exceeding 99.9%, 90%, and 96%, respectively. 2+ Formation of cationic complex [Ni(H2O)6]² + It precipitates as high-purity nickel malonate, while Co remains stable in solution as an anionic complex [CoCl4]. 2- Then, oxalic acid was used to precipitate the cobalt to obtain the recovered product, a cobalt-containing complex.

[0026] The lithium battery cathode material applicable to the method of the present invention is any cathode material containing one or more of nickel, cobalt and manganese, preferably a ternary cathode material of lithium nickel cobalt manganese oxide, including but not limited to NCM811, SC-811, PC-811, NCM613, NCM622, NCM523, etc.

[0027] In some embodiments, the heating temperature in step (1) is 80~120 ℃. The heating temperature in step (2) is 80~120 ℃. The drying temperature for the black gelatinous mixture in step (3) is 100~200 ℃, and the drying time is 10~20 h. The grinding time in step (3) is 1~2 h.

[0028] In some embodiments, the sintering process in step (3) includes a first sintering process and a second sintering process performed sequentially; In the first sintering process, the sintering temperature is 300~600 ℃ and the sintering time is 4~7 h; In the second sintering process, the sintering temperature is 600~1000 ℃, and the sintering time is 2~10 h. The main component of the recycled product of lithium battery cathode material (taking LiCoO2 as an example) is oxalate, which has extremely low solubility in aqueous solvents, making it difficult to achieve atomic-level mixing. Traditional preparation methods cannot directly utilize the recycled product to prepare air electrode materials. The principle of this invention is speculated to be as follows: This invention uses organic sugar as a solvent and amino compounds as a co-solvent. The organic sugar and amino compounds are mixed and heated to form a transparent, homogeneous, eutectic solvent. Then, a metal salt is mixed in the molten eutectic solvent to form a homogeneous system. Drying is then performed to rapidly remove the remaining solvent (mainly water, possibly containing a small amount of volatile small-molecule organic matter), allowing the metal ions to be fixed in situ on the amide groups formed by the sugar and amino compounds. Subsequently, high-temperature treatment is performed to polymerize and carbonize the organic sugar under high-temperature conditions, and the gas generated by the decomposition of the amino compounds uniformly distributes the metal ions, ultimately forming a solid oxide fuel cell air electrode material with uniform particle size.

[0029] Traditionally, it has been believed that high-purity metal salts should be used as raw materials to prepare high-performance air electrode materials for solid oxide batteries, in order to avoid impurities adversely affecting product performance. However, this invention unexpectedly discovered that not all impurities are harmful. In this invention, recycled semi-finished metal complexes are used as raw materials, and the trace amounts of Li impurities contained therein can actually significantly improve product performance.

[0030] The solid oxide fuel cell air electrode material obtained by this invention exhibits uniform size at the nanoscale and an appropriate specific surface area, demonstrating excellent electrochemical performance. It was incidentally discovered that using metal complexes recovered from spent lithium-ion battery cathode materials as raw materials, containing trace amounts of lithium (≤0.5 wt%), yields the best-performing air electrode material under suitable atomic ratios. Experimental comparisons revealed that replacing the material with pure nitrates of the corresponding metal element actually reduced the performance of the resulting air electrode material. It is speculated that this is because pure nitrates lack low-valence lithium ion doping, leading to a decrease in oxygen vacancy concentration and thus a decline in air electrode material performance.

[0031] The composition design of the air electrode material for solid oxide fuel cells described in this invention is convenient and controllable, and the porosity and specific surface area of ​​the product can be further adjusted by changing the ratio of sugar and ammonium salts. This provides a new approach for the preparation and performance optimization of air electrode materials for solid oxide fuel cells.

[0032] This invention discloses a method for preparing a high-efficiency solid oxide fuel cell air electrode material based on recycled lithium battery cathode materials. Belonging to the interdisciplinary field of electrode material recycling and fuel cell technology, the aim is to achieve high-value utilization of recycled waste materials and obtain high-performance solid oxide fuel cell air electrode materials. This method directly uses semi-finished complexes generated from recycled lithium battery cathode materials as raw materials. Utilizing the strong complexing ability of a eutectic system formed by sugars and amino compounds, it achieves the dissolution of the poorly soluble recycled materials and atomic-level mixing with other metal salt raw materials to obtain a high-performance air electrode material. The material prepared from recycled lithium battery cathode materials is free of impurity phases, exhibits a uniform nanostructure, and has a small lattice constant. Unexpectedly, the material obtained by this invention exhibits superior electrochemical performance compared to similar materials prepared using traditional raw materials in electrochemical tests. Research shows that impurity elements in the recycled products may significantly improve the electrochemical performance of the material through doping effects. This invention not only verifies the feasibility of eutectic systems in the recycling and reuse of waste lithium battery materials but also provides an innovative solution for the low-cost and green preparation of solid oxide fuel cell air electrode materials through an integrated "recycling-reconstruction-performance optimization" strategy.

[0033] The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0034] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0035] The embodiments of this application are described below with reference to the accompanying drawings.

[0036] Example 1 A type of LSCF air electrode material (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Its synthesis process includes the following steps: 1) Weigh 6g of anhydrous glucose and 10g of urea into small beakers, stir at 110℃ for 30min until completely dissolved to form a homogeneous eutectic solvent. 2) Weigh out 1.9468 g of lanthanum nitrate hexahydrate, 0.6343 g of strontium nitrate, and 2.4218 g of ferric nitrate nonahydrate, respectively, and then... 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Weigh out the cobalt-containing complex of the recovered product (calculated as all of the recovered product is cobalt oxalate dihydrate) according to the stoichiometric ratio, add it to the obtained homogeneous eutectic solvent, and stir at 110°C for about 1.5 hours to mix the various substances evenly, to obtain a black colloidal mixture. The recovered product is a metal complex obtained from the wet recovery of lithium battery cathode materials via a choline chloride-malonic acid system. The main component of this complex is cobalt oxalate, containing trace amounts of lithium impurities (≤0.5% by mass). The specific recovery steps are as follows: choline chloride (ChCl), a hydrogen bond donor, and malonic acid, a hydrogen bond acceptor, are mixed in a round-bottom flask at a molar ratio of 2:1 and stirred at 60°C for 2 hours without further treatment until a homogeneous and transparent liquid is formed. Subsequently, 20wt% water is added as a diluent. The prepared choline chloride-malonic acid DES (containing 20wt% H2O) is used to leach NCM811 cathode powder at 100°C for 45 minutes, followed by filtration. The solid-liquid ratio during leaching is 20 mg:1 mL. A 0.2 mol / L oxalic acid solution is added to the filtrate as a precipitant, controlling the volume ratio of the leachate to the oxalic acid solution to be 1:3. The mixture is then stirred at 80°C for 60 minutes. After the reaction was completed, the mixture was filtered while hot, and the resulting pink precipitate was collected. It was then washed several times with deionized water and dried overnight in a vacuum drying oven at 60°C. The final solid obtained was the recovered cobalt-containing complex.

[0037] 3) The obtained black gelatinous mixture was placed in a drying oven at 200 °C for heat treatment for 12 h, and then ground for 1 h to obtain a black solid powder. 4) The obtained black solid powder was calcined in air; the sintering treatment included a first sintering process and a second sintering process performed sequentially; in the first sintering process, the sintering temperature was 500 ℃ and the sintering time was 5 h; in the second sintering process, the sintering temperature was 700 ℃ and the sintering time was 3 h. After cooling, La was obtained. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Material.

[0038] Comparative Example 1 The rest is the same as in Example 1, except that the cobalt complex in the recovered product was replaced with 0.4362 g of analytically pure cobalt nitrate hexahydrate.

[0039] Figure 1 A schematic diagram of X-ray diffraction of the LSCF air electrode material prepared in Example 1 is shown. (Reference) Figure 1 By combining the PDF card, it can be seen that the material exhibits a pure perovskite phase, indicating that there are no impurity phases. It is understood that the PDF mentioned here refers to a Powder Diffraction File, which is generally understood as a standard database for XRD phase analysis. In other words, by comparing the experimental data with the standard diffraction peaks in the PDF card, it can be determined that the experimental sample is a pure phase.

[0040] Raman spectroscopy analysis was performed on the air electrode material prepared in Example 1, and the results are as follows: Figure 2 As shown. Under ordinary Raman testing conditions, the material signal is weak (10). -2 No obvious characteristic peaks were detected, indicating that the instrument was approaching its detection limit. However, by utilizing the surface-enhanced Raman effect, the Raman scattering cross-section of molecules adsorbed on the surface can be magnified by 10⁻⁶. 4 This allows for the detection of weak signals at the same excitation power, exceeding the limit by more than double. Under SERS testing conditions, it can detect signals up to 481 cm⁻¹. -1 A clear signal peak was observed. According to the literature (Joule 6, 1290-1303, June 15, 2022), this peak is attributed to the coupling vibration of Li-O bond and transition metal M (such as Co, Fe)-O bond.

[0041] In addition, ICP-MS (inductively coupled plasma mass spectrometry) analysis was performed on the cobalt-containing complex in the recovered material from step (2). The results showed that the main components were cobalt, etc., and no Li element was detected. Combined with Raman spectroscopy analysis, it can be inferred that the recovered material may contain the impurity element Li, but the content is very low, below the detection limit of ICP-MS and ordinary Raman spectroscopy analysis. Figure 1 XRD phase analysis results further indicate that the trace impurity element Li in the recovered product has entered the interior of the LSCF unit cell and exists stably in the perovskite structure as a dopant. Furthermore, the concentration is below the detection limits of ICP-MS and conventional Raman spectroscopy, indicating that the lithium content in the recovered product is ≤0.5 wt%.

[0042] Figure 2 A schematic diagram of the surface-enhanced Raman spectrum of the LSCF air electrode material prepared in Example 1 is shown. (Reference) Figure 2 The material is 481 cm -1 The signal peak appears at this location, which is attributed to the vibration of the Li-O bond; combined with Figure 1 XRD phase analysis showed that the impurity element Li in the recovered material entered the LSCF unit cell of the material in Example 1 and existed as a dopant element in the perovskite structure.

[0043] Figure 3 A schematic diagram of a scanning electron microscope is shown of the LSCF air electrode material prepared in Example 1. Figure 3 These are morphology results at a scale of 100 nm. (Reference) Figure 3 The LSCF powder prepared in this embodiment has a particle size between 100-300 nm, high material uniformity, and small particle size.

[0044] The LSCF powder prepared in Example 1 was mixed with a binder and screen-printed onto both sides of the GDC electrolyte surface, then calcined at 1000°C to form an electrode with an active area of ​​0.14 square centimeters. The prepared symmetrical cell was placed on the test platform of the test furnace, and the current collectors on both sides were connected to the electrodes of the electrochemical workstation via silver wires. Electrochemical impedance was measured in an air atmosphere at 600°C, 650°C, 700°C, 750°C, and 800°C, and the test results are shown below. Figure 4 As shown. Reference Figure 4 At the same test temperature, the polarization impedance of Example 1 is significantly smaller than that of Comparative Example 1, indicating that the battery prepared by the LSCF air electrode material of Example 1 has good battery output performance.

[0045] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a cathode for a solid oxide fuel cell using recycled materials from spent lithium battery cathodes, characterized in that, Includes the following steps: (1) Mix sugars and amino compounds and heat to form a transparent, homogeneous eutectic solvent; (2) Add lithium battery cathode recovery material and optional other metal salt materials to the eutectic solvent, heat and stir to obtain a black gel-like mixture; wherein the recovery material is a metal complex obtained by wet recovery of lithium battery cathode material by eutectic solvent, the metal complex contains at least one of nickel, cobalt and manganese complexes, and contains residual lithium element; The other metal salt materials are used to provide other metal elements that are not included in the recycled materials and are required for the air electrode materials; (3) The black gel-like mixture is dried, ground and sintered to obtain an air electrode material for solid oxide fuel cells.

2. The method according to claim 1, characterized in that, The sugars are one or more of glucose, fructose, sucrose, maltose, starch, cellulose, ribose, and lactose.

3. The method according to claim 1, characterized in that, The amino compound is urea and / or ammonium nitrate.

4. The method according to claim 1, characterized in that, The recycled material is a metal complex obtained by wet recycling of lithium battery cathode material using a eutectic solvent. The main component of the complex is oxalate, which contains trace amounts of lithium impurities, with a mass fraction of ≤0.5%.

5. The method according to claim 4, characterized in that, The method for recovering the material includes the following steps: leaching the lithium nickel cobalt manganese oxide ternary cathode material with a eutectic solvent at 90-100℃ for 30-60 minutes and then performing solid-liquid separation; adding oxalic acid as a precipitant to the filtrate obtained from the solid-liquid separation; heating and stirring to cause cobalt to precipitate; after the reaction is completed, separating the solid and liquid; washing and drying the separated precipitate to obtain the cobalt-containing complex recovered material. The preparation of the eutectic solvent is based on the hydrogen bonding between choline chloride as a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond donor is one or more of oxalic acid, malonic acid, tartaric acid, glutaric acid, malic acid, and succinic acid.

6. The method according to claim 1, characterized in that, The heating temperature in step (1) is 80~120℃.

7. The method according to claim 1, characterized in that, The heating temperature in step (2) is 80~120℃.

8. The method according to claim 1, characterized in that, In step (3), the temperature for drying the black gel-like mixture is 100~200 ℃ and the drying time is 10~20 h.

9. The method according to claim 1, characterized in that, The grinding time in step (3) is 1~2 hours.

10. The method according to claim 1, characterized in that, The sintering process in step (3) includes a first sintering process and a second sintering process performed sequentially. In the first sintering process, the sintering temperature is 300~600 ℃ and the sintering time is 4~7 h; In the second sintering process, the sintering temperature is 600~1000 ℃ and the sintering time is 2~10 h.

Images