A high-performance lithium iron phosphate cathode material, a preparation method and application thereof

Abstract

The application discloses a high-performance lithium iron phosphate positive electrode material and a preparation method and application thereof. The lithium iron phosphate positive electrode material is prepared by a sol-gel method, and a thermal stabilizer is added after sintering to improve the thermal stability of the lithium iron phosphate positive electrode material, so that the risk of thermal runaway of a battery is reduced, and the safety of the battery is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a high-performance lithium iron phosphate cathode material, its preparation method, and its application. Background Technology

[0002] The main advantages of lithium iron phosphate (LFP) cathode materials lie in their excellent thermal stability and safety, making them a more ideal choice than other common cathode materials (such as lithium cobalt oxide and lithium nickel cobalt oxide). LFP does not undergo severe thermal runaway reactions during cycling, thus significantly reducing the risk of battery fire or explosion. Furthermore, LFP materials have lower production costs and abundant raw material sources.

[0003] However, the low energy density of lithium iron phosphate is one of its biggest drawbacks, mainly due to its low electronic and ionic conductivity, which often limits its performance, especially under high-rate discharge and low-temperature conditions. Therefore, improving the conductivity of lithium iron phosphate, optimizing its crystal structure, and enhancing its surface and interface properties are among the key research directions for lithium iron phosphate materials.

[0004] Currently, the preparation methods for lithium iron phosphate mainly include solid-state methods, sol-gel methods, and hydrothermal synthesis methods. Among them, the solid-state method is the most common and widely used preparation method, which usually involves a high-temperature reaction of a mixture of iron sources (such as ferric chloride and ferric nitrate) and phosphorus sources (such as diammonium hydrogen phosphate and phosphoric acid). For example, there is the invention application with publication number CN120039851A. However, the main disadvantages of the solid-state method are the high reaction temperature and the long reaction time, resulting in high energy consumption. In addition, the obtained lithium iron phosphate particles are large, have poor surface activity, and low conductivity, which limits its application in high-power batteries.

[0005] The sol-gel method has been widely used in recent years due to its advantages such as mild reaction conditions, simple preparation process, ability to achieve uniform dispersion, and low-temperature synthesis. This method can synthesize uniform and small-sized lithium iron phosphate particles at relatively low temperatures and effectively improve their electrochemical performance. For example, the invention application with publication number CN113991070A. However, the complexing agents (such as ethylene glycol) and solvent systems (such as water and ethanol) commonly used in the traditional sol-gel method need to be strictly controlled to avoid over-polymerization or incomplete complexation reactions. Due to the resistance to lithium-ion diffusion, the capacity and cycle stability of the battery decrease after multiple charge-discharge cycles. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a sol-gel method for preparing high-performance lithium iron phosphate cathode materials. The sol-gel method proposed in this invention not only optimizes the performance of lithium iron phosphate by rationally controlling the synthesis process, but also enables the preparation of high-performance lithium iron phosphate cathode materials by selecting appropriate solvents, complexing agents, and pH adjusters.

[0007] This invention first provides a method for preparing a high-performance lithium iron phosphate cathode material, comprising the following steps:

[0008] S1, dissolves iron source, lithium source and phosphorus source in solvent to form sol;

[0009] S2, add a complexing agent to the sol, adjust the pH and then gel to obtain a gel;

[0010] S3, the gel is dried to obtain a precursor, the precursor is sintered, and then an enhanced thermal stabilizer is added to obtain lithium iron phosphate cathode material.

[0011] Preferably, in step S1, the iron source includes at least one of iron nitrate, iron chloride, iron sulfate, iron acetate, and their respective hydrates;

[0012] The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium chloride, and lithium nitrate;

[0013] The phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, sodium dihydrogen phosphate, and aluminum trichloride phosphate;

[0014] The solvent includes at least one of acetone and ethanol;

[0015] In step S2, the complexing agent is ethylene glycol.

[0016] Preferably, in step S1, based on 100 parts by weight of iron source, lithium source is 95-110 parts, phosphorus source is 115-130 parts, and solvent is 250-400 parts.

[0017] In step S2, the mass of the complexing agent is 8%-15% of the mass of the iron source.

[0018] Preferably, in step S2, the pH is adjusted to 3.5-4.2.

[0019] Preferably, in step S3, the drying temperature is 105-120℃ and the drying time is 10-18 hours; the sintering temperature is 650-800℃ and the sintering time is 4-8 hours, and the sintering atmosphere is an oxygen atmosphere.

[0020] Preferably, the enhanced heat stabilizer is generated by a nucleophilic substitution reaction between 2-fluoro-4-(pentafluorothio)aniline and perfluoropolyether alcohol under the catalysis of a catalyst.

[0021] By mass, 24-50 parts of 2-fluoro-4-(pentafluorothio)aniline and 75-150 parts of perfluoropolyether alcohol are added to a solvent, and then 4%-7% of triethylamine (as a catalyst) is added to the solvent. The mixture is reacted at 80-90°C for 3-6 hours. After the reaction is completed, methanol is added to precipitate the product. The precipitate is separated and dried to obtain the heat stabilizer.

[0022] Preferably, the amount of the enhanced heat stabilizer added is 0.1%-0.5% of the mass of the product obtained after precursor sintering; after the enhanced heat stabilizer is added, it is mixed at 85-100°C for 2-5 hours.

[0023] The present invention also provides a high-performance lithium iron phosphate cathode material prepared by the aforementioned preparation method.

[0024] This invention further provides the application of the high-performance lithium iron phosphate cathode material in the preparation of lithium-ion batteries.

[0025] Beneficial effects of this invention:

[0026] 1. Through the action of complexing agents, metal ions can be better dispersed and stabilized during the synthesis process, avoiding unfavorable aggregation on the particle surface. The optimized surface structure reduces the resistance to lithium-ion diffusion, enabling the battery to maintain high capacity and good cycle stability after multiple charge-discharge cycles.

[0027] 2. By adjusting the proportions of components, pH value, and synthesis temperature during the sol-gel process, the lithium iron phosphate material synthesized by this method exhibits a high specific surface area and a small particle size. These characteristics not only improve the electronic and ionic conductivity of the material but also enable the battery to have high energy density and excellent high-rate discharge performance.

[0028] 3. Improved thermal stability of lithium iron phosphate cathode material: Due to the high bond energy of the CF bond in the enhanced thermal stabilizer, the decomposition temperature of lithium iron phosphate cathode material is effectively increased; the SF group can capture HF during battery thermal runaway, generating LiF and SF6, inhibiting the chain reaction, which significantly improves the thermal stability of the cathode material, reduces the risk of battery thermal runaway, and greatly enhances the safety of battery use. Attached Figure Description

[0029] Figure 1 This is an electron microscope image of the lithium iron phosphate cathode material prepared in Example 3. Detailed Implementation

[0030] Example 1

[0031] 1. Raw material preparation:

[0032] Iron source: 100g of ferrous nitrate hexahydrate (Fe(NO3)2·6H2O, purity ≥99%);

[0033] Lithium source: 100g of lithium carbonate (Li2CO3, purity ≥99.5%);

[0034] Phosphorus source: Diammonium hydrogen phosphate ((NH4)2HPO4, purity ≥99%) 120g;

[0035] Solvent: 300g of anhydrous ethanol (C2H6O, analytical grade);

[0036] Complexing agent: ethylene glycol (C2H6O2), the amount used is 10% (10g) of the iron source mass;

[0037] pH adjuster: a combination of dilute nitric acid (HNO3, 0.1 mol / L) and potassium hydroxide (KOH, 0.1 mol / L) solution.

[0038] 2. Sol preparation: Dissolve the iron, lithium, and phosphorus sources in ethanol, add ethylene glycol, and stir at room temperature (25°C) until completely dissolved. Adjust the pH to 4.0 by adding HNO3 / KOH dropwise, and continue stirring for 2 hours to form a homogeneous sol.

[0039] 3. Gelation: Transfer the sol to a constant temperature incubator (20℃) and let it stand for 18 hours to form a transparent gel.

[0040] 4. Drying treatment: The gel was placed in an oven at 110℃ and dried for 15 hours to obtain a fluffy precursor powder.

[0041] 5. Sintering treatment: The precursor powder is placed in a tube furnace and heated to 700℃ at a rate of 1.5℃ / min under an oxygen atmosphere, and held for 6 hours.

[0042] 6. Heat stabilizer modification: After cooling the sintered product to 90°C, add 0.1 wt% of a heat stabilizer enhancement agent and mix at high speed for 3 hours. The preparation method of the heat stabilizer enhancement agent is as follows:

[0043] Weigh 24g of 2-fluoro-4-(pentafluorothio)aniline and 75g of perfluoropolyether alcohol. Add the above raw materials to 270g of DMF solvent, and then add triethylamine accounting for 4wt% of the total mass of the reactants. React at 80°C for 6 hours. After the reaction is completed, methanol is added to precipitate the product. Filter to separate the precipitate, and then dry it under vacuum at 50°C for 24 hours to obtain the enhanced heat stabilizer.

[0044] Example 2

[0045] 1. Raw material preparation:

[0046] Iron source: 100g of ferric chloride hexahydrate (FeCl3·6H2O, purity ≥99%);

[0047] Lithium source: 95g of lithium hydroxide monohydrate (LiOH·H2O, purity ≥99%);

[0048] Phosphorus source: Phosphoric acid (H3PO4, 85% concentration) 115g;

[0049] Solvent: 250g of acetone (C3H6O, analytical grade);

[0050] Complexing agent: ethylene glycol, used at 8% (8g) of the iron source mass;

[0051] pH adjuster: a combination of hydrochloric acid (HCl, 0.1 mol / L) and sodium hydroxide (NaOH, 0.1 mol / L) solution.

[0052] 2. Sol preparation: Iron, lithium, and phosphorus sources were dissolved in acetone, and ethylene glycol was added. The mixture was then ultrasonically dispersed for 30 minutes. The pH was adjusted to 3.8 with HCl / NaOH, and the mixture was stirred for 1 hour to form a sol.

[0053] 3. Gel formation: The sol is placed in an environment of 22°C and left to stand for 12 hours to form a gel.

[0054] 4. Drying treatment: The gel was dried at 105℃ for 18 hours to obtain a low-density precursor.

[0055] 5. Sintering treatment: Heat to 650℃ at 1℃ / min under an oxygen atmosphere and hold for 8 hours.

[0056] 6. Heat stabilizer modification: Add 0.25 wt% of a heat stabilizer enhancement agent at 85℃ and ball mill for 4 hours. The preparation method of the heat stabilizer enhancement agent is as follows:

[0057] Weigh 36g of 2-fluoro-4-(pentafluorothio)aniline and 100g of perfluoropolyether alcohol. Add the above raw materials to 320g of DMF solvent, and then add triethylamine accounting for 5wt% of the total mass of the reactants. React at 85°C for 5 hours. After the reaction is completed, methanol is added to precipitate the product. Filter to separate the precipitate, and then dry it under vacuum at 55°C for 20 hours to obtain the enhanced heat stabilizer.

[0058] Example 3

[0059] 1. Raw material preparation:

[0060] Iron source: 100g of ferric sulfate nonhydrate (Fe2(SO4)3·9H2O, purity ≥99%);

[0061] Lithium source: 110g of lithium nitrate (LiNO3, purity ≥99%);

[0062] Phosphorus source: Sodium dihydrogen phosphate (NaH2PO4, purity ≥99%) 125g;

[0063] Solvent: 350g ethanol;

[0064] Complexing agent: ethylene glycol, used at 12% (12g) of the iron source mass.

[0065] pH adjuster: a combination of phosphoric acid (H3PO4, 0.1 mol / L) and ammonia (NH3·H2O, 0.1 mol / L) solution.

[0066] 2. Sol preparation: The raw materials were dissolved in ethanol, and ethylene glycol was added followed by mechanical stirring for 4 hours. The pH was adjusted to 4.2 using H3PO4 / NH3·H2O to form a sol.

[0067] 3. Gel formation: Gel is formed by standing at 25°C for 20 hours.

[0068] 4. Drying treatment: Dry the gel at 115℃ for 12 hours.

[0069] 5. Sintering treatment: Heat to 750℃ at 2℃ / min under oxygen atmosphere and hold for 5 hours.

[0070] 6. Heat stabilizer modification: Add 0.4 wt% of enhanced heat stabilizer at 95℃ and stir at high speed for 2 hours. The method for preparing the enhanced heat stabilizer is as follows:

[0071] Weigh 45g of 2-fluoro-4-(pentafluorothio)aniline and 125g of perfluoropolyether alcohol. Add the above raw materials to 360g of DMF solvent, and then add triethylamine accounting for 6wt% of the total mass of the reactants. React at 85°C for 4 hours. After the reaction is completed, methanol is added to precipitate the product. The precipitate is separated by filtration and then dried under vacuum at 55°C for 22 hours to obtain the enhanced heat stabilizer.

[0072] Figure 1 This is an electron microscope image of the lithium iron phosphate cathode material prepared in Example 3.

[0073] Example 4

[0074] 1. Raw material preparation:

[0075] Iron source: ferrous nitrate hexahydrate (60g) + ferrous acetate tetrahydrate (Fe(C2H3O2)2·4H2O, 40g);

[0076] Lithium source: Lithium carbonate (50g) + Lithium hydroxide (50g);

[0077] Phosphorus source: Diammonium hydrogen phosphate (130g);

[0078] Solvent: Ethanol (400g);

[0079] Complexing agent: ethylene glycol, used at 15% (15g) of the total mass of the iron source.

[0080] pH adjuster: dilute nitric acid (HNO3, 0.1 mol / L).

[0081] 2. Sol preparation: Iron, lithium, and phosphorus sources were dissolved in ethanol, and ethylene glycol was added followed by magnetic stirring for 3 hours. The pH was adjusted to 3.5 with HNO3 to form a sol.

[0082] 3. Gel formation: Gel is formed by standing at 23°C for 24 hours.

[0083] 4. Drying treatment: Dry the gel at 120℃ for 10 hours.

[0084] 5. Sintering treatment: Heat to 800℃ at 1.2℃ / min under oxygen atmosphere and hold for 4 hours.

[0085] 6. Heat stabilizer modification: Add 0.5 wt% of enhanced heat stabilizer at 100℃ and ball mill for 5 hours. The method for preparing the enhanced heat stabilizer is as follows:

[0086] Weigh 50g of 2-fluoro-4-(pentafluorothio)aniline and 150g of perfluoropolyether alcohol. Add the above raw materials to 400g of DMF solvent, and then add triethylamine accounting for 7wt% of the total mass of the reactants. React at 90°C for 3 hours. After the reaction is completed, methanol is added to precipitate the product. Filter to separate the precipitate, and then vacuum dry at 60°C for 18 hours to obtain the enhanced heat stabilizer.

[0087] Comparative Example 1

[0088] 1. Raw material preparation:

[0089] Iron source: 100g of ferrous nitrate hexahydrate (Fe(NO3)2·6H2O, purity ≥99%);

[0090] Lithium source: 100g of lithium carbonate (Li2CO3, purity ≥99.5%);

[0091] Phosphorus source: Diammonium hydrogen phosphate ((NH4)2HPO4, purity ≥99%) 120g;

[0092] Solvent: 300g of anhydrous ethanol (C2H6O, analytical grade);

[0093] Complexing agent: ethylene glycol (C2H6O2), the amount used is 10% (10g) of the iron source mass;

[0094] pH adjuster: a combination of dilute nitric acid (HNO3, 0.1 mol / L) and potassium hydroxide (KOH, 0.1 mol / L) solution.

[0095] 2. Sol preparation: Dissolve the iron, lithium, and phosphorus sources in ethanol, add ethylene glycol, and stir at room temperature (25°C) until completely dissolved. Adjust the pH to 4.0 by adding HNO3 / KOH dropwise, and continue stirring for 2 hours to form a homogeneous sol.

[0096] 3. Gelation: Transfer the sol to a constant temperature incubator (20℃) and let it stand for 18 hours to form a transparent gel.

[0097] 4. Drying treatment: The gel was placed in an oven at 110℃ and dried for 15 hours to obtain a fluffy precursor powder.

[0098] 5. Sintering treatment: The precursor powder is placed in a tube furnace and heated to 700℃ at a rate of 1.5℃ / min under an oxygen atmosphere, and held for 6 hours.

[0099] No heat stabilizer was added for modification.

[0100] Comparative Example 2

[0101] 1. Raw material preparation:

[0102] Iron source: 100g of ferrous nitrate hexahydrate (Fe(NO3)2·6H2O, purity ≥99%);

[0103] Lithium source: 100g of lithium carbonate (Li2CO3, purity ≥99.5%);

[0104] Phosphorus source: Diammonium hydrogen phosphate ((NH4)2HPO4, purity ≥99%) 120g;

[0105] Solvent: 300g of anhydrous ethanol (C2H6O, analytical grade);

[0106] Complexing agent: ethylene glycol (C2H6O2), the amount used is 10% (10g) of the iron source mass;

[0107] pH adjuster: a combination of dilute nitric acid (HNO3, 0.1 mol / L) and potassium hydroxide (KOH, 0.1 mol / L) solution.

[0108] 2. Sol preparation: Dissolve the iron, lithium, and phosphorus sources in ethanol, add ethylene glycol, and stir at room temperature (25°C) until completely dissolved. Adjust the pH to 4.0 by adding HNO3 / KOH dropwise, and continue stirring for 2 hours to form a homogeneous sol.

[0109] 3. Gelation: Transfer the sol to a constant temperature incubator (20℃) and let it stand for 18 hours to form a transparent gel.

[0110] 4. Drying treatment: The gel was placed in an oven at 110℃ and dried for 15 hours to obtain a fluffy precursor powder.

[0111] 5. Sintering treatment: The precursor powder is placed in a tube furnace and heated to 700℃ at a rate of 1.5℃ / min under an oxygen atmosphere, and held for 6 hours.

[0112] 6. Heat stabilizer modification: After cooling the sintered product to 90°C, add 0.1 wt% of a heat stabilizer enhancement agent and mix at high speed for 3 hours. The preparation method of the heat stabilizer enhancement agent is as follows:

[0113] Weigh 75g of perfluoropolyether alcohol, add the above raw materials to 270g of DMF solvent, and then add triethylamine accounting for 4wt% of the total mass of the reactants. React at 80°C for 6 hours. After the reaction is completed, methanol is added to precipitate the product. The precipitate is separated by filtration and then dried under vacuum at 50°C for 24 hours to obtain an enhanced heat stabilizer without the addition of 2-fluoro-4-(pentafluorothio)aniline.

[0114] Comparative Example 3

[0115] 1. Raw material preparation:

[0116] Iron source: 100g of ferrous nitrate hexahydrate (Fe(NO3)2·6H2O, purity ≥99%);

[0117] Lithium source: 100g of lithium carbonate (Li2CO3, purity ≥99.5%);

[0118] Phosphorus source: Diammonium hydrogen phosphate ((NH4)2HPO4, purity ≥99%) 120g;

[0119] Solvent: 300g of anhydrous ethanol (C2H6O, analytical grade);

[0120] Complexing agent: ethylene glycol (C2H6O2), the amount used is 10% (10g) of the iron source mass;

[0121] pH adjuster: a combination of dilute nitric acid (HNO3, 0.1 mol / L) and potassium hydroxide (KOH, 0.1 mol / L) solution.

[0122] 2. Sol preparation: Dissolve the iron, lithium, and phosphorus sources in ethanol, add ethylene glycol, and stir at room temperature (25°C) until completely dissolved. Adjust the pH to 4.0 by adding HNO3 / KOH dropwise, and continue stirring for 2 hours to form a homogeneous sol.

[0123] 3. Gelation: Transfer the sol to a constant temperature incubator (20℃) and let it stand for 18 hours to form a transparent gel.

[0124] 4. Drying treatment: The gel was placed in an oven at 110℃ and dried for 15 hours to obtain a fluffy precursor powder.

[0125] 5. Sintering treatment: The precursor powder is placed in a tube furnace and heated to 700℃ at a rate of 1.5℃ / min under an oxygen atmosphere, and held for 6 hours.

[0126] 6. Heat stabilizer modification: After cooling the sintered product to 90°C, add 0.1 wt% of a heat stabilizer enhancement agent and mix at high speed for 3 hours. The preparation method of the heat stabilizer enhancement agent is as follows:

[0127] Weigh 24g of 2-fluoro-4-(pentafluorothio)aniline, add the above raw material to 270g of DMF solvent, and then add triethylamine accounting for 4wt% of the total mass of the reactants. React at 80°C for 6 hours. After the reaction is completed, methanol is added to precipitate the product. The precipitate is separated by filtration and then dried under vacuum at 50°C for 24 hours to obtain the enhanced heat stabilizer without the addition of perfluoropolyether alcohol.

[0128] Detection Example 1:

[0129] The testing method involved in this invention is as follows:

[0130] (1) Electrochemical performance testing

[0131] Equipment: Cyclic voltammetry (CV) and charge-discharge performance testing were performed using a standard battery testing system (LAND CT2001A).

[0132] Test method:

[0133] A symmetric battery was prepared using lithium iron phosphate as the positive electrode, graphite as the negative electrode, and 1M LiPF6 solution as the electrolyte.

[0134] Charge-discharge tests are used to measure the battery's specific capacity, cycle performance, rate performance, and other properties.

[0135] For the cycle performance test, the charge / discharge current density was set to 0.1C, and 500 cycles were performed.

[0136] For rate performance testing, discharge current densities of 1C and 5C were set for testing.

[0137] (2) High-temperature performance test using an environmental test chamber. Test method: Discharge test is performed under an environmental condition of 60°C, and the performance changes of the material at different temperatures are observed.

[0138] Table 1 Test Results

[0139]

[0140] The test results above demonstrate that metal ions are better dispersed and stabilized during the synthesis process, avoiding unfavorable aggregation on the particle surface. The optimized surface structure reduces the resistance to lithium-ion diffusion, enabling the battery to maintain high capacity and good cycle stability after multiple charge-discharge cycles.

[0141] The lithium iron phosphate material prepared by the sol-gel method provided by this invention has certain technical advantages in terms of electrochemical performance, cycle performance and high and low temperature adaptability, and can meet the demand for high-performance lithium iron phosphate materials in the fields of electric vehicles and energy storage.

Claims

1. A method for preparing high-performance lithium iron phosphate cathode material, characterized in that, The method comprises the following steps: S1, dissolving an iron source, a lithium source and a phosphorus source in a solvent to form a sol; S2, adding a complexing agent to the sol, adjusting pH and then performing gelation to obtain a gel; S3, drying the gel to obtain a precursor, sintering the precursor, and then adding a heat stabilizer to obtain a lithium iron phosphate positive electrode material; The heat stabilizer is prepared by adding 24-50 parts of 2-fluoro-4-(pentafluorothio) aniline and 75-150 parts of perfluoropolyether alcohol to a solvent, adding 4%-7% of triethylamine based on the total mass of the reactants, and then reacting at 80-90°C for 3-6 hours. After the reaction is completed, methanol is added for precipitation, the precipitate is separated and dried to obtain the heat stabilizer.

2. The method of claim 1, wherein the high performance lithium iron phosphate cathode material is prepared by the steps of: In step S1, the iron source includes at least one of iron nitrate, iron chloride, iron sulfate, iron acetate and their respective hydrates; ​ The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium chloride and lithium nitrate; The phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, sodium dihydrogen phosphate and aluminum phosphate trichloride; The solvent includes at least one of acetone and ethanol; In step S2, the complexing agent is ethylene glycol.

3. The method for preparing the high-performance lithium iron phosphate cathode material according to claim 1, characterized in that, In step S1, based on 100 parts of the mass of the iron source, the lithium source is 95-110 parts, the phosphorus source is 115-130 parts, and the solvent is 250-400 parts; In step S2, the mass of the complexing agent is 8%-15% of the mass of the iron source.

4. The method for preparing the high-performance lithium iron phosphate cathode material according to claim 1, characterized in that, In step S2, the pH is adjusted to 3.5-4.

2.

5. The method for preparing the high-performance lithium iron phosphate cathode material according to claim 1, characterized in that, In step S3, the drying temperature is 105-120°C, the drying time is 10-18 hours; the sintering temperature is 650-800°C, the sintering time is 4-8 hours, and the sintering atmosphere is an oxygen atmosphere.

6. The method for preparing the high-performance lithium iron phosphate cathode material according to claim 1, characterized in that, The addition amount of the heat stabilizer is 0.1%-0.5% of the mass of the product obtained after sintering of the precursor; and the heat stabilizer is mixed at 85-100°C for 2-5 hours after being added.

7. A high-performance lithium iron phosphate positive electrode material prepared by the method of any one of claims 1-6.

8. The use of the high-performance lithium iron phosphate positive electrode material of claim 7 in the preparation of a lithium ion battery.

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