Perovskite-doped positive electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion battery materials, and discloses a perovskite-doped positive electrode material as well as a preparation method and application thereof. The preparation method of the perovskite-doped positive electrode material provided by the invention comprises the following steps: S1, mixing a lithium source, a phosphorus source, an iron source, an element A source, an element B source, an organic carbon source and a solvent to obtain a precursor solution; and S2, performing spray pyrolysis on the precursor solution to obtain the perovskite-doped lithium iron phosphate positive electrode material, the spray pyrolysis comprises the steps of atomizing the precursor solution into liquid drops, and sequentially carrying out a preheating stage, a reaction stage and a cooling stage; segmented temperature control is adopted in the reaction stage. According to the method, a one-step spray pyrolysis method is adopted, so that the process flow is remarkably simplified, the production efficiency is greatly improved, and the electrochemical performance of the material is improved while the energy consumption is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, specifically to a perovskite-doped cathode material, its preparation method, and its application. Background Technology

[0002] Currently, lithium-ion battery cathode materials are mainly prepared using solid-state and multi-step liquid-phase methods. These methods generally suffer from problems such as long process flows, high energy consumption, and difficulty in controlling component uniformity. Especially for perovskite-doped modified cathode materials, traditional methods require complex processes such as precursor synthesis, mixing, and multiple sintering, which not only consumes a lot of energy but also easily leads to component segregation and particle agglomeration. Existing Chinese patent publication number CN118162053A discloses a method for preparing a cathode material doped with a specific perovskite structure, employing a two-step process. First, a perovskite precursor is prepared using a solution method, and then mixed with the cathode matrix material followed by high-temperature solid-state sintering. Its core innovation lies in the element selection and ratio optimization of the perovskite phase; however, the preparation process still follows traditional methods, resulting in complex processes and high energy consumption.

[0003] Spray pyrolysis, as a potential alternative process, has shown unique advantages in the field of materials synthesis. This method directly yields uniformly composed nanoscale particles by atomizing the precursor solution and instantly decomposing it in a high-temperature reactor. However, existing spray pyrolysis technology still has many limitations in the preparation of lithium-ion battery cathode materials: 1) Poor precursor compatibility: Traditional two-fluid nozzles struggle to simultaneously process lithium sources and perovskite precursors with significantly different chemical properties; 2) Imperfect crystal structure: One-step pyrolysis cannot simultaneously guarantee the formation of the perovskite phase and the crystallinity of the cathode material; 3) Mismatched process parameters: Lithium-ion battery cathode materials require strict stoichiometry and crystal structure, which are difficult to precisely control under conventional spray pyrolysis conditions.

[0004] Existing Chinese patent publication number CN116666602A discloses a method for preparing high-nickel cathode materials using spray pyrolysis. This patent focuses on high-nickel ternary material systems and employs a modified spray pyrolysis technology, optimizing the material structure by controlling the temperature profile and atmosphere conditions. However, this technology does not involve perovskite doping, and the spray pyrolysis yields a precursor rather than directly producing the cathode material. A secondary heat treatment calcination at 500-700℃ for 2-6 hours is required to obtain the cathode material, therefore it cannot be considered a true one-step process. Another Chinese patent publication number CN102456928A discloses a spray pyrolysis manufacturing method for bilayer thin-film all-solid-state lithium-ion batteries. This patent uses a dual-spray gun technology to form a buffer layer, improving interlayer matching. However, its application is limited to thin-film batteries, and the process is highly complex, requiring precise control of the flow rates of the two precursor solutions, making it unsuitable for large-scale production of cathode active materials. Furthermore, Chinese patent publication number CN103000893A discloses a spray pyrolysis preparation method for lithium manganese phosphate cathode materials for lithium batteries. This patent uses spray pyrolysis to prepare lithium manganese phosphate cathode materials, but the process explicitly requires subsequent calcination treatment (calcination at 500-850℃ for 2-6 hours), failing to fully utilize the one-step forming advantage of spray pyrolysis. In addition, Chinese patent publication number CN202110856572X discloses modified lithium phosphate cathode materials and their preparation method. Although this method uses spray pyrolysis, it mainly addresses the hydrophobicity of the material rather than structural uniformity or energy consumption issues. Its process includes multiple pretreatment steps such as coarse grinding and fine grinding, making the process relatively complex.

[0005] In summary, current spray pyrolysis technology still faces the problem of balancing energy consumption and performance in cathode material preparation. Existing technologies either sacrifice energy consumption for performance or focus on simplifying the process but the material performance is not ideal. There is a lack of an optimized solution that can balance both aspects. Summary of the Invention

[0006] This invention provides a perovskite-doped cathode material, its preparation method, and its application, in order to solve the problem of balancing energy consumption and performance in the prior art.

[0007] In a first aspect, the present invention provides a method for preparing a perovskite-doped cathode material, comprising the following steps: Step S1: Mix lithium source, phosphorus source, iron source, element A source, element B source, organic carbon source and solvent to obtain precursor solution; element A includes rare earth elements and / or alkaline earth metals; element B includes transition metal elements and / or tin; the molar ratio of element A to element B is 1:0.8-1.2. Step S2: The precursor solution is subjected to spray pyrolysis to obtain perovskite-doped lithium iron phosphate cathode material.

[0008] The spray pyrolysis includes atomizing the precursor solution into droplets and sequentially performing a preheating stage, a reaction stage, and a cooling stage.

[0009] The temperature during the preheating stage is 200-350℃.

[0010] The reaction stage includes a front section and a rear section; the temperature of the front section is 300-600℃, and the temperature of the rear section is 700-800℃.

[0011] The function of the preheating stage is to rapidly dry the droplet surface to form a porous shell, and then to form a uniform mixture at the atomic level through segmented temperature control in the reaction stage. The function of the cooling stage is to control crystal growth and stress release.

[0012] In one optional embodiment, the molar ratio of iron in the iron source to phosphorus in the phosphorus source and lithium in the lithium source is 1:0.8-1.2:1.05-1.08, and the excess lithium source can compensate for the lithium loss caused by high-temperature volatilization.

[0013] In one alternative embodiment, the total mass of elements A and B accounts for 0.5-4.5% of the total mass of the perovskite-doped lithium iron phosphate cathode material.

[0014] In one optional embodiment, the carbon content in the cathode material is 3wt%-6wt%, based on the total mass of the doped perovskite cathode material as 100%.

[0015] In one optional embodiment, the total concentration of metal ions in the precursor solution is 0.1-1.5 mol / L.

[0016] In one optional embodiment, the lithium source includes at least one of lithium acetate, lithium nitrate, lithium carbonate, and lithium hydroxide.

[0017] In one optional embodiment, the iron source includes at least one of ferric phosphate, ferric oxide, ferrous oxalate, and ferric nitrate, preferably ferric phosphate.

[0018] In one optional embodiment, the D50 particle size of the iron phosphate is 0.5-10 μm.

[0019] In one alternative embodiment, the phosphorus source comprises ammonium dihydrogen phosphate and / or phosphoric acid, preferably ammonium dihydrogen phosphate.

[0020] In one optional embodiment, the A element source includes rare earth element nitrates, rare earth metal acetates, alkaline earth metal nitrates, and alkaline earth metal acetates.

[0021] In one alternative embodiment, the source of element B includes transition metal nitrates and / or tin chloride.

[0022] In one alternative embodiment, the rare earth element includes at least one selected from lanthanum, praseodymium, neodymium, gadolinium, cerium, promethium, samarium, and europium.

[0023] In one alternative embodiment, the alkaline earth metal includes at least one of calcium, strontium, and barium.

[0024] In one alternative embodiment, the transition metal element includes at least one of manganese, cobalt, and nickel.

[0025] In one alternative embodiment, the organic carbon source includes a primary carbon source and / or an auxiliary carbon source.

[0026] In one alternative embodiment, the solvent comprises water and ethanol. The primary solvent is deionized water with a resistivity ≥18 MΩ•cm, and the co-solvent is anhydrous ethanol, which can improve the solubility of the organic precursor. A water-to-ethanol ratio of 7:3 (v / v) can optimize solubility and atomization.

[0027] In one optional embodiment, the main carbon source includes at least one selected from sucrose, citric acid, glucose, fructose, cellulose, and starch. In one alternative embodiment, the auxiliary carbon source comprises polyvinylpyrrolidone (PVP). PVP serves as both an auxiliary carbon source and a dispersant.

[0028] In one alternative implementation, the reaction phase further includes an intermediate stage.

[0029] In one alternative embodiment, the temperature of the middle section is 600-750°C.

[0030] In one optional embodiment, the atomization frequency is 2.0-2.5MHz; the atomization flow rate is 1-5L / h; and the atomization temperature is 80-100℃. Maintaining the atomization temperature at 80-100℃ can prevent precursor crystallization.

[0031] In one optional embodiment, the D50 particle size of the droplet is 2-8 μm; the particle size distribution deviation is ≤15%.

[0032] In one optional embodiment, the carrier gas in the spray pyrolysis comprises nitrogen with a purity ≥99.999%. The dew point of the atmosphere in the spray pyrolysis is ≤-40℃, and the impurity content is ≤1ppm.

[0033] In one optional embodiment, the carrier gas flow rate is 8-12 L / min, and the carrier gas temperature is 200-250°C. A carrier gas temperature of 200-250°C helps prevent premature cooling of the droplets.

[0034] In one alternative embodiment, the carrier gas further includes 0-5% by volume hydrogen.

[0035] In one alternative implementation, the preheating phase lasts for 3-5 seconds.

[0036] In one alternative implementation, the total time for the preheating and reaction phases is 10-30 seconds.

[0037] In one alternative embodiment, the outlet temperature of the cooling stage is ≤150°C. Controlling the cooling rate during the cooling stage can prevent thermal stress cracking.

[0038] In one alternative embodiment, the cooling stage includes a first cooling stage and a second cooling stage, wherein the first cooling stage cools the product to ≤400°C and the second cooling stage cools the product to ≤150°C.

[0039] In one alternative implementation, the cooling stage further includes the steps of collecting and post-processing the reaction products.

[0040] In one optional embodiment, the collection involves primary collection of the reaction products using a cyclone separator and / or secondary collection using a bag filter, followed by gas purification using a ceramic filter. The primary collection using a cyclone separator has a collection efficiency of ≥95%, the secondary collection using a bag filter can collect fine powder with a particle size ≤0.5μm, and the ceramic filter is used for gas purification to ensure that the exhaust gas emissions meet the standards.

[0041] In one optional embodiment, the post-treatment is vacuum drying; the vacuum drying temperature is 100-120℃ and the time is 3-5 hours.

[0042] The instruments used in spray pyrolysis are equipped with a multi-parameter linkage control system. Among them, the online laser particle size analyzer can monitor the particle size distribution in real time; the infrared thermal imager can monitor the temperature field uniformity of the reactor; the gas mass spectrometer can analyze the exhaust gas composition and provide feedback to adjust the process parameters; and the automatic control system can be based on a PLC (programmable logic controller) intelligent control system to achieve accurate reproduction of process parameters.

[0043] Secondly, the present invention also provides a perovskite-doped cathode material, wherein the perovskite-doped cathode material is prepared by the above-mentioned method for preparing perovskite-doped cathode materials.

[0044] Thirdly, the present invention also provides the application of the above-mentioned perovskite-doped cathode material in the preparation of lithium-ion batteries.

[0045] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing a perovskite-doped cathode material, comprising the following steps: Step S1: Mixing a lithium source, a phosphorus source, an iron source, an element A source, an element B source, an organic carbon source, and a solvent to obtain a precursor solution; wherein the element A includes rare earth elements and / or alkaline earth metals; the element B includes transition metal elements and / or tin; the molar ratio of the elements A and B is 1:0.8-1.2; Step S2: Performing spray pyrolysis on the precursor solution to obtain a perovskite-doped lithium iron phosphate cathode material; the spray pyrolysis includes atomizing the precursor solution into droplets, and sequentially performing a preheating stage, a reaction stage, and a cooling stage; the temperature of the preheating stage is 200-350℃; the reaction stage includes a front section and a rear section; the temperature of the front section is 300-600℃, and the temperature of the rear section is 700-800℃. This invention significantly simplifies the process flow by employing a one-step spray pyrolysis method. Compared to traditional multi-step processes, the preparation method of this invention requires only one spray pyrolysis step. During spray pyrolysis, preheating is performed at 200-350°C, followed by pyrolysis at a lower temperature (300-600°C) and then further pyrolysis at a higher temperature (700-800°C) to obtain the cathode material. No secondary heat treatment is needed, reducing production costs and shortening the preparation cycle from several hours in traditional processes to just a few minutes, significantly improving production efficiency. Furthermore, it significantly reduces energy consumption while enhancing the electrochemical performance of the material. In the preparation method provided by this invention, the raw materials are in an ionic state during the reaction, achieving uniform mixing of components at the atomic scale. This results in a uniform distribution of the perovskite phase in the cathode material, effectively avoiding local segregation and facilitating electrolyte wetting while reducing side reactions.

[0046] By eliminating the high-temperature sintering step in traditional processes (which typically requires maintaining 700-900℃ for several hours, or even tens of hours), the energy consumption of the preparation method in this invention is significantly lower than that of traditional solid-state methods. Simultaneously, the reduced reaction temperature and shorter equipment operating time lead to a corresponding decrease in equipment wear and tear, further reducing maintenance costs. Due to the substantial reduction in energy consumption, labor, equipment investment, and maintenance costs, the total cost of the final product is significantly lower than that of traditional methods.

[0047] By sequentially performing a preheating stage, a reaction stage, and a cooling stage through a spray pyrolysis process, and employing a segmented temperature-controlled spray pyrolysis process, combined with element A (including rare earth elements and / or alkaline earth metals) and element B (including transition metal elements and / or tin) at a specific molar ratio of A to B elements, a perovskite-doped lithium iron phosphate cathode material can be formed, which can significantly improve the battery's discharge specific capacity and cycle performance.

[0048] 2. This invention provides a method for preparing a perovskite-doped cathode material. The solvent used to prepare the precursor solution is a water-based solvent system, avoiding the use of large amounts of organic solvents and reducing volatile organic compound emissions at the source. The closed reaction system ensures no dust leakage during production, and the dust concentration in the working environment easily meets industry standards. Simultaneously, due to the significant reduction in energy consumption, carbon dioxide emissions are correspondingly reduced, demonstrating good environmental friendliness. Attached Figure Description

[0049] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the spray pyrolysis device used in this invention. Detailed Implementation

[0051] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0052] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0053] Schematic diagrams of the spray pyrolysis apparatus used in the various embodiments and comparative examples of this invention are shown below. Figure 1 As shown, the precursor solution is delivered from the atomizer via a carrier gas pipeline in series with a preheating chamber (i.e., preheating zone) and a multi-stage reaction chamber (i.e., reaction zones A, B, and C). The preheating chamber and the multi-stage reaction chamber are integrated into a tubular furnace. The tubular furnace is equipped with multiple sets of temperature sensors and heating components to independently control the temperature of the preheating chamber and the multi-stage reaction chamber. Its discharge end is connected to a shell-and-tube quench cooler or a fluidized bed cooler via a diversion pipeline. The discharge end of the shell-and-tube quench cooler or the fluidized bed cooler is directly connected to a cyclone separator or a bag filter. The bag filter is connected in series with the cyclone separator, or both can be used simultaneously to separate the obtained products.

[0054] Example 1 This embodiment provides a method for preparing a perovskite-doped cathode material, comprising the following steps: (1) Preparation of precursor solution: Accurately weigh 10.83g lithium acetate (LiCH3COO•2H2O), 18.90g iron phosphate (FePO4•2H2O, D50 particle size of 0.5-1μm), 0.65g lanthanum nitrate (La(NO3)3•6H2O), 0.38g manganese nitrate (Mn(NO3)2•4H2O), and 8.55g sucrose. Dissolve the above raw materials in 500mL of a mixed solvent of deionized water and ethanol (volume ratio of 7:3), and stir magnetically for 2 hours in a water bath at 45℃ to obtain a homogeneous precursor solution with a total metal ion (lithium, iron, lanthanum, manganese) concentration of 0.42mol / L; (2) An ultrasonic atomizer installed at the top of the spray pyrolysis device was used to liquefy the above precursor into droplets with a D50 particle size of 3-8 μm under the conditions of atomization frequency of 2.2 MHz, flow rate of 3 L / h, and temperature of 90 ℃. The flow rate of the carrier gas (using 98% volume fraction high-purity nitrogen and 2% volume fraction hydrogen) in the spray pyrolysis device was set to 10 L / min, and the carrier gas temperature was set to 200 ℃. The spray pyrolysis device was divided into a preheating zone, a reaction zone, and a cooling zone. The atomized droplets first entered the 200 ℃ preheating zone (i.e., the preheating stage) and stayed in the preheating zone for 4 s. Then they entered the cooling zone. The product enters the reaction zone (i.e., the reaction stage), which is divided into a front section, a middle section, and a rear section from top to bottom. The reaction temperature in the front section is 300℃, and the residence time of the droplets is 4s; the reaction temperature in the middle section is 600℃, and the residence time of the droplets is 4s; the reaction temperature in the rear section is 750℃, and the residence time of the droplets is 8s. The product then enters the cooling zone (i.e., the cooling stage), which includes two stages of cooling. The first stage involves cooling the powder to below 400℃ in a shell-and-tube cooler, and the second stage involves cooling the material to below 150℃ in a fluidized bed cooler. (3) Material collection and post-processing: The product was collected by a cyclone separator and dried under vacuum at 120°C for 4 hours to obtain 17.1g of lithium iron manganese phosphate cathode material doped with perovskite (LaMnO3) with a carbon content of 5wt%.

[0055] Example 2 This embodiment provides a method for preparing a perovskite-doped cathode material, comprising the following steps: (1) Preparation of precursor solution: Accurately weigh 3.88g lithium carbonate (Li2CO3), 18.00g ferrous oxalate (FeC2O4·2H2O), 11.50g ammonium dihydrogen phosphate (NH4H2PO4), 0.511g barium acetate (Ba(CH3COO)2), 0.70g tin chloride pentahydrate (SnCl4·5H2O), 5.93g glucose and 2.00g polyvinylpyrrolidone. Add the above raw materials to 600mL of deionized water in sequence, and stir magnetically for 3 hours under the protection of nitrogen gas at 60℃ to obtain a homogeneous precursor suspension with a total metal ion concentration of about 0.35 mol / L. During the process, dilute nitric acid is used to adjust the pH to 3.0. (2) An ultrasonic atomizer installed at the top of the spray pyrolysis device is used to atomize the above precursor suspension into droplets of 5-8 μm at an atomization frequency of 2.5 MHz, a flow rate of 5 L / h, and a temperature of 80 ℃. The carrier gas (using high-purity nitrogen with a purity of 99.99%) flow rate is controlled at 12 L / min, and the carrier gas temperature is 250 ℃. The spray pyrolysis device is divided into a preheating zone, a reaction zone, and a cooling zone. The atomized droplets first enter the preheating zone at 350 ℃ (i.e., the preheating stage), and the residence time in the preheating zone is 3 s. Then they enter the reaction zone (i.e., the reaction stage). The reaction zone is divided into a front section, a middle section, and a rear section from top to bottom. The reaction temperature in the front section is 550℃, and the droplet residence time is 5s; the reaction temperature in the middle section is 750℃, and the droplet residence time is 8s; the reaction temperature in the rear section is 800℃, and the droplet residence time is 10s. The resulting product then enters the cooling zone (i.e., the cooling stage). The cooling stage includes two stages of cooling: the first stage involves cooling the powder to below 400℃ in a shell-and-tube cooler, and the second stage involves cooling the material to below 150℃ in a fluidized bed cooler. (3) Material collection and post-processing: The product was collected by a bag filter and then the collected powder was vacuum dried at 100°C for 5 hours to obtain 17.4g of lithium iron phosphate cathode material doped with perovskite (BaSnO3) with a carbon content of 6wt%.

[0056] Example 3 This embodiment provides a method for preparing a perovskite-doped cathode material, comprising the following steps: (1) Preparation of precursor solution: Accurately weigh 4.54 g lithium hydroxide monohydrate (LiOH·H2O), 40.40 g ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 13.20 g diammonium hydrogen phosphate ((NH4)2HPO4), 1.13 g gadolinium nitrate hexahydrate (Gd(NO3)3·6H2O), 0.73 g cobalt nitrate hexahydrate (Co(NO3)2·6H2O), and 5.93 g glucose. Dissolve the above raw materials in a mixed solvent of 400 mL deionized water and 100 mL anhydrous ethanol, and stir magnetically for 1 hour in a water bath at 50 °C to obtain a deep red transparent solution with a total metal ion concentration of approximately 0.426 mol / L; (2) An ultrasonic atomizer installed at the top of the spray pyrolysis device is used to atomize the above-mentioned precursor sol into droplets of 2-8 μm under the conditions of atomization frequency of 2.0 MHz, flow rate of 1 L / h, and temperature of 100 ℃. The carrier gas (using high-purity nitrogen with a purity of 99.99%) flow rate is controlled at 8 L / min, and the carrier gas temperature is 200 ℃. The spray pyrolysis device is divided into a preheating zone, a reaction zone, and a cooling zone. The atomized droplets first enter the 200 ℃ preheating zone (i.e., the preheating stage), and the residence time in the preheating zone is... 4s; then enter the reaction zone (i.e., the reaction stage), which is divided into a front section and a rear section from top to bottom. The reaction temperature in the front section is 600℃ and the residence time of the droplets is 10s; the reaction temperature in the rear section is 700℃ and the residence time of the droplets is 15s; then the obtained product enters the cooling zone (i.e., the cooling stage), which adopts two-stage cooling. The first stage is a rapid cooling heat exchanger to quickly cool the powder to below 300℃, and the second stage is a conveying channel that introduces deep dehumidified cold air to cool the material to room temperature; (3) Material collection and post-processing: The product was collected by connecting a cyclone separator and a bag filter in series. The collected powder was then dried in a vacuum drying oven at 110°C for 4 hours to obtain 17.3g of perovskite (GdCoO3) doped lithium iron phosphate cathode material with a carbon content of 5wt%.

[0057] Comparative Example 1 This comparative example provides a method for preparing a perovskite-doped cathode material, which is basically the same as that in Example 1, except that lanthanum nitrate and manganese nitrate in step (1) are omitted.

[0058] Comparative Example 2 This comparative example provides a method for preparing a perovskite-doped cathode material, which is basically the same as that in Example 2, except that in step (1), 0.61g of BaSnO3 is used directly to replace barium acetate and tin chloride pentahydrate.

[0059] Comparative Example 3 This comparative example provides a method for preparing a perovskite-doped cathode material, comprising the following steps: accurately weighing 4.54 g of lithium hydroxide monohydrate (LiOH·H2O), 40.40 g of ferric nitrate nonahydrate (Fe(NO2)2·9H2O), 13.20 g of diammonium hydrogen phosphate ((NH4)2HPO4), 1.13 g of gadolinium nitrate hexahydrate (Gd(NO3)3·6H2O), and 0.73 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), mixing them in a ball mill for 2 hours, then placing them in a crucible, and placing them in a small tube furnace, calcining them at 750°C under a high-purity nitrogen atmosphere with a purity of 99.99% for 12 hours to obtain the cathode material.

[0060] Experimental Example 1 The cathode materials prepared in each embodiment and comparative example were assembled into coin cells for performance testing. Subsequently, their cycle performance was characterized by the discharge capacity retention rate after 500 cycles of 1C charge / 1C discharge.

[0061] 1. The positive electrode materials obtained in each embodiment and comparative example are assembled into coin cells. The preparation method of the coin cells is as follows: (1) Preparation of positive electrode sheet: The positive electrode materials obtained in each example and comparative example and polyvinylidene fluoride: carbon black were mixed evenly at a mass ratio of 95:2.5:2.5. Then, an appropriate amount of N-methylpyrrolidone (NMP) solvent was added and stirred to form a uniform slurry. The slurry was evenly coated on the aluminum foil current collector, dried under vacuum at 120°C, and compacted by roller pressing. The slurry was then punched into circular electrode sheets with a diameter of 12 mm for later use. (2) Preparation of negative electrode sheet: Using a metallic lithium sheet as the counter electrode, it is punched into a circular lithium sheet with a diameter of 15 mm in an argon glove box for later use. (3) Preparation of electrolyte: The electrolyte is a 1.0 mol / L lithium hexafluorophosphate (LiPF6) solution, and the solvent is a mixed solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio 1:1). (4) Assembly: In a glove box filled with argon, the negative electrode shell, negative electrode sheet (lithium sheet) are placed in sequence, electrolyte is added, separator (Celgard 2400) is laid, positive electrode sheet is placed, electrolyte is added, positive electrode shell is covered, and sealing is done by sealing machine to obtain CR2032 button cell. The assembled battery is tested after standing for 24 hours.

[0062] 2. Perform performance tests on the prepared button cells. Test method: Place the battery in a constant temperature environment of 25℃ and test it using a battery testing system, setting the voltage range to 2.5V-3.8V (vs. Li). + / Li). The first three cycles used 0.2C constant current charging / 0.2C constant current discharging, with a constant voltage charging cutoff current of 0.05C, and the first discharge specific capacity was recorded; Cycle and rate performance test: After completing the first three cycles, the battery was charged to 3.8V at a 1C charging rate, with a constant voltage charging cutoff current of 0.05C, and discharged to 2.5V at a 1C discharging rate, and the first discharge specific capacity was recorded. After 500 cycles, the discharge specific capacity after 500 cycles was recorded, and the capacity retention rate was calculated by dividing the discharge specific capacity after 500 cycles by the first discharge specific capacity at a 1C rate × 100%.

[0063] 3. Test results: as shown in Table 1 below.

[0064] Table 1 Performance Test Results

[0065] As shown in Table 1, Example 1 exhibits a higher initial discharge capacity and excellent cycle stability compared to the comparative example, with a capacity retention of 95.0% after 500 cycles. This is attributed to the atomic-level composite of the perovskite phase and the cathode substrate material, rather than simple physical mixing or surface coating. The preparation method of this invention can control the decomposition and recombination of the perovskite precursor during crystal growth, enabling it to form a coherent interface with the matrix material, thereby greatly reducing interfacial impedance and improving ion migration efficiency.

[0066] In contrast, the lithium manganese iron phosphate cathode material in Comparative Example 1 had a first-cycle capacity of only 150 mAh / g and a capacity retention rate of only 86.8% after 500 cycles, indicating poor performance. This may be due to the absence of perovskite additives.

[0067] Compared with Comparative Example 2, Example 2 has atomic-level mixing between the perovskite dopant and the precursor, while the latter is only a solid-phase mixture. Therefore, the initial discharge capacity and 500-cycle performance of Example 2 are better than those of Comparative Example 2.

[0068] Compared with Comparative Example 3, Example 3 uses a one-step preparation method, and the spray pyrolysis process used in the reaction is much shorter than the calcination time used in the Comparative Example. In addition, the first-cycle discharge capacity and cycle performance are also better than those of Comparative Example 3.

[0069] The preparation method of the present invention greatly reduces the preparation time of the cathode material. In the current laboratory pilot stage, the spray pyrolysis equipment used in Example 3 of the present invention has a power of about 15kW and a reaction time of only 25s, with low energy consumption. In contrast, the small tube furnace used in Comparative Example 3 has a power of 2-3kW, a reaction time of 12 hours, and an energy consumption of 24-36kWh, which is relatively high. Therefore, the preparation method of the present invention can further reduce energy consumption, and also significantly reduce labor and equipment investment and maintenance costs.

[0070] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a perovskite-doped cathode material, characterized in that, Includes the following steps: Step S1: Mix lithium source, phosphorus source, iron source, element A source, element B source, organic carbon source and solvent to obtain precursor solution; the element A includes rare earth elements and / or alkaline earth metals; the element B includes transition metal elements and / or tin; the molar ratio of element A to element B is 1:0.8-1.

2. Step S2: The precursor solution is subjected to spray pyrolysis to obtain perovskite-doped lithium iron phosphate cathode material; The spray pyrolysis includes atomizing the precursor solution into droplets and sequentially performing a preheating stage, a reaction stage, and a cooling stage. The temperature during the preheating stage is 200-350℃; The reaction stage includes a front section and a rear section; the temperature of the front section is 300-600℃, and the temperature of the rear section is 700-800℃.

2. The method for preparing the doped perovskite cathode material according to claim 1, characterized in that, The molar ratio of iron in the iron source to phosphorus in the phosphorus source and lithium in the lithium source is 1:0.8-1.2:1.05-1.08; And / or, the total mass of elements A and B accounts for 0.5-4.5% of the total mass of the perovskite-doped lithium iron phosphate cathode material; And / or, based on the total mass of the perovskite-doped cathode material as 100%, the carbon content in the cathode material is 3wt%-6wt%; And / or, the total concentration of metal ions in the precursor solution is 0.1-1.5 mol / L.

3. The method for preparing the doped perovskite cathode material according to claim 1 or 2, characterized in that, The lithium source includes at least one of lithium acetate, lithium nitrate, lithium carbonate, and lithium hydroxide; And / or, the iron source includes at least one of ferric phosphate, ferric oxide, ferrous oxalate, and ferric nitrate, preferably ferric phosphate; Optionally, the D50 particle size of the iron phosphate is 0.5-10 μm; And / or, the phosphorus source includes ammonium dihydrogen phosphate and / or phosphoric acid, preferably ammonium dihydrogen phosphate; And / or, the source of element A includes rare earth element nitrates, rare earth metal acetates, alkaline earth metal nitrates, and alkaline earth metal acetates; And / or, the source of element B includes transition metal nitrates and / or tin chloride.

4. The method for preparing the doped perovskite cathode material according to claim 1 or 3, characterized in that, The rare earth elements include at least one of lanthanum, praseodymium, neodymium, gadolinium, cerium, promethium, samarium, and europium; And / or, the alkaline earth metal includes at least one of calcium, strontium, and barium; And / or, the transition metal element includes at least one of manganese, cobalt, and nickel; And / or, the organic carbon source includes a primary carbon source and / or an auxiliary carbon source; And / or, the solvent includes water and ethanol.

5. The method for preparing the doped perovskite cathode material according to claim 4, characterized in that, The primary carbon source includes at least one of sucrose, citric acid, glucose, fructose, cellulose, and starch. And / or, the auxiliary carbon source includes polyvinylpyrrolidone.

6. The method for preparing the doped perovskite cathode material according to claim 1, characterized in that, The reaction stage also includes an intermediate stage; Optionally, the temperature of the middle section is 600-750℃; And / or, the atomization frequency is 2.0-2.5MHz; the atomization flow rate is 1-5L / h; and the atomization temperature is 80-100℃; And / or, the D50 particle size of the droplets is 2-8 μm; And / or, the carrier gas in the spray pyrolysis includes nitrogen; Optionally, the carrier gas flow rate is 8-12 L / min, and the carrier gas temperature is 200-250℃; Optionally, the carrier gas may further include 0-5% by volume hydrogen.

7. The method for preparing the doped perovskite cathode material according to claim 1, characterized in that, The preheating phase lasts for 3-5 seconds. And / or, the total time for the preheating stage and the reaction stage is 10-30 s; And / or, the outlet temperature of the cooling stage is ≤150°C.

8. The method for preparing the doped perovskite cathode material according to claim 1, characterized in that, The cooling stage includes a first cooling stage and a second cooling stage. The first cooling stage cools the product to ≤400°C, and the second cooling stage cools the product to ≤150°C. And / or, the cooling stage may further include the steps of collecting and post-processing reaction products; Optionally, the collection involves primary collection of the reaction products using a cyclone separator and / or secondary collection using a bag filter, followed by gas purification using a ceramic filter. Optionally, the post-treatment is vacuum drying; the vacuum drying temperature is 100-120℃ and the time is 3-5 hours.

9. A perovskite-doped cathode material, characterized in that, The doped perovskite cathode material is prepared by the method for preparing doped perovskite cathode material according to any one of claims 1-8.

10. The application of the perovskite-doped cathode material according to claim 9 in the preparation of lithium-ion batteries.

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