Preparation method of lithium-containing iron phosphate precursor, lithium-containing iron phosphate precursor and lithium iron phosphate

Abstract

The invention provides a preparation method of a lithium-containing iron phosphate precursor, the lithium-containing iron phosphate precursor and lithium iron phosphate. The method comprises the following steps: mixing waste lithium iron phosphate battery powder with pure water, adding an oxidizing agent and hydrochloric acid for acid leaching, and filtering to obtain an acid leaching solution and acid leaching residues; adding waste lithium iron phosphate battery powder and an oxidizing agent into the pickle liquor to adjust the pH value, so as to obtain a lithium-containing solution; carrying out washing and acid leaching on the acid leaching residues to obtain phosphorus and iron acid leaching liquid containing phosphorus and iron; removing impurities from the ferrophosphorus acid leaching solution to obtain an impurity-removed solution; mixing the lithium-containing solution and the impurity removal solution to obtain a lithium-containing ferrophosphorus solution; and carrying out spray pyrolysis on the lithium-containing ferrophosphorus solution to obtain a lithium-containing iron phosphate precursor. By directly treating the waste battery powder, the step of preparing an intermediate product in a traditional method is avoided, so that the cost is reduced. Meanwhile, by accurately controlling the reaction conditions of each step, the introduction of impurities is reduced to the maximum extent, and the high purity of the final product is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of battery materials, and in particular to a method for preparing a lithium-containing iron phosphate precursor, a lithium-containing iron phosphate precursor, and lithium iron phosphate. Background Art

[0002] At present, due to the non-standard recycling policy, the quality of waste lithium iron phosphate black powder varies greatly. The iron phosphate and lithium carbonate prepared by traditional wet process recycling either have extremely high production costs and are not cost-effective, or the purity of the prepared iron phosphate and lithium carbonate does not meet the requirements for preparing lithium iron phosphate materials for batteries. The traditional industrial method for preparing lithium iron phosphate materials is to use battery-grade iron phosphate, battery-grade lithium carbonate and carbon source in a certain proportion, after solid phase grinding and mixing, and high-temperature sintering. It has extremely high requirements for the purity of iron phosphate and lithium carbonate. This makes it a rather embarrassing situation to use waste lithium iron phosphate black powder to directly prepare lithium iron phosphate materials for batteries.

[0003] Therefore, some companies are currently attempting to adopt an alternative approach to re-prepare waste lithium iron phosphate black powder into lithium iron phosphate material for batteries, such as sintering after mixing, or as reported in patent CN202311586655.7, first using spray pyrolysis to prepare a lithium iron phosphate precursor, and then mixing it with a carbon source and sintering it to prepare lithium iron phosphate.

[0004] The problem with the former is that the existing mixing equipment cannot guarantee its uniformity, and the prepared lithium iron phosphate material has the problem of poor consistency in electrochemical performance. The latter requires that the solution before spray pyrolysis has extremely high purity. According to the above, the current traditional method for recovering lithium iron phosphate black powder is still mainly wet method. Generally, high-purity iron phosphate and lithium carbonate are prepared by wet process first, and then dissolved. In this process, it is inevitable to use a large amount of acid and alkali, which is costly, and a large amount of wastewater will be generated, which is difficult to handle. The most critical thing is that the pre-spray pyrolysis liquid containing lithium, iron, and phosphorus prepared by this method inevitably contains a large amount of sodium ions or ammonium ions, which makes the sodium or ammonium ions in the lithium iron phosphate prepared by spray pyrolysis extremely high, and the subsequent treatment is extremely troublesome.

[0005] Therefore, providing a method for preparing a lithium iron phosphate precursor with less impurities has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The embodiments of the present application provide a method for preparing a lithium-containing iron phosphate precursor, a lithium-containing iron phosphate precursor, and lithium iron phosphate.

[0007] The embodiment of the present application provides a method for preparing a lithium-containing iron phosphate precursor, comprising mixing waste lithium iron phosphate battery powder with pure water, adding an oxidant and hydrochloric acid for acid leaching, filtering to obtain an acid leaching solution and an acid leaching residue; adding the waste lithium iron phosphate battery powder and the oxidant to the acid leaching solution to adjust the pH value to obtain a lithium-containing solution; washing and acid leaching the acid leaching residue to obtain a ferrophosphorus acid leaching solution containing phosphorus and iron; removing impurities from the ferrophosphorus acid leaching solution to obtain an impurity-removing liquid; mixing the lithium-containing solution and the impurity-removing liquid to obtain a lithium-containing ferrophosphorus solution; and spray pyrolyzing the lithium-containing ferrophosphorus solution to obtain a lithium-containing iron phosphate precursor.

[0008] In some embodiments, the waste lithium iron phosphate powder is mixed with pure water, hydrogen peroxide and hydrochloric acid are added for acid leaching, and the acid leaching liquid and acid leaching residue are obtained after filtering, which comprises:

[0009] Mixing waste lithium iron phosphate battery powder with pure water into a slurry, adding an oxidant dropwise to the slurry and then adding hydrochloric acid to adjust the pH value to 4.5 to 5, and obtaining a primary acid leaching solution and a primary acid leaching residue after solid-liquid separation;

[0010] The primary acid leaching residue is added with pure water and hydrochloric acid to adjust the pH value to 1 to 2, and filtered to obtain a secondary acid leaching solution and secondary acid leaching residue.

[0011] In some embodiments, the waste lithium iron phosphate battery powder is mixed with pure water to form a slurry, an oxidant is added to the slurry, and then hydrochloric acid is added to adjust the pH value to 4.5 to 5, and a primary acid leaching solution and a primary acid leaching residue are obtained after solid-liquid separation, including:

[0012] The waste lithium iron phosphate battery powder and pure water are mixed into a slurry at a ratio of 1 to 5, an oxidant and hydrochloric acid are slowly added to the slurry to adjust the pH value to 4.5 to 5, and stirred at 50-65° C. for 4-8 hours, and a primary acid leaching solution and a primary acid leaching residue are obtained after solid-liquid separation;

[0013] The step of adding pure water and hydrochloric acid to the primary acid leaching residue to adjust the pH value to 1 to 2, and filtering to obtain a secondary acid leaching solution and secondary acid leaching residue comprises:

[0014] The primary acid leaching residue is added with pure water and hydrochloric acid to adjust the pH value to 1 to 2, and stirred at 55-65° C. for 6-8 hours, and filtered to obtain a secondary acid leaching solution and secondary acid leaching residue.

[0015] In some embodiments, the oxidant is any one of hydrogen peroxide, oxygen, ozone, and sodium persulfate. When the oxidant is hydrogen peroxide, the mass ratio of the waste lithium iron phosphate battery powder to hydrogen peroxide is about 1:0.4-0.8, and the mass ratio to hydrochloric acid is about 1:0.2-0.3.

[0016] In some embodiments, the step of adding the acid leaching solution to waste lithium iron phosphate battery powder and hydrogen peroxide to adjust the pH value to obtain a lithium-containing solution comprises:

[0017] Add the acid leaching solution into the waste lithium iron phosphate battery powder and stir, and slowly add hydrogen peroxide to the solution to adjust the pH value to 6-8. The ratio of waste lithium iron phosphate battery powder to solution used for adjusting the pH value is about 1:10-15. After stirring at 50-60°C for 30min-2h, add the defluorination agent, stir at room temperature for 1-2h for solid-liquid separation to obtain a lithium-containing solution.

[0018] In some embodiments, washing and acid leaching the acid leaching residue to obtain a ferrophosphorus acid leaching solution containing phosphorus and iron comprises:

[0019] The acid leaching residue is added with pure water at a liquid-to-solid ratio of about 3 to 5:1, stirred and slurried, hydrochloric acid is added to adjust the pH value of the slurry to 1-2, and the temperature is raised to 50 to 70° C., and stirring is continued for 1 to 2 hours to obtain ferrophosphorus slag with low nickel, cobalt and manganese content;

[0020] Add pure water to the ferrophosphorus slag with low nickel, cobalt and manganese content at a solid-liquid ratio of 1:5, stir and slurry, then add hydrochloric acid and iron powder, stir for 5-6 hours, and then filter to obtain the ferrophosphorus acid leaching solution containing phosphorus and iron.

[0021] In some embodiments, removing impurities from the ferrophosphorus acid leaching solution to obtain the impurity-removed liquid comprises:

[0022] Add an aluminum remover to the ferrophosphide acid leaching solution, stir for 1-2 hours at room temperature, filter, then add a fluorine remover, continue stirring for 1-2 hours, and obtain a decontamination solution.

[0023] In some embodiments, mixing the lithium-containing solution and the impurity removal solution to obtain a lithium-phosphorus-containing iron solution comprises:

[0024] The phosphorus-iron ratio in the lithium-phosphorus-iron solution is adjusted, wherein the molar ratio of iron to phosphorus in the lithium-phosphorus-iron solution is (0.95-1.00):1;

[0025] The step of spraying pyrolysis of the lithium-containing iron phosphate solution to obtain a lithium-containing iron phosphate precursor comprises:

[0026] Concentrating the lithium-phosphorus-iron solution to obtain a concentrated solution;

[0027] atomizing the concentrated liquid to obtain atomized liquid droplets;

[0028] The atomized liquid droplets are sintered from top to bottom in a synthesis furnace under the action of gravity, and the sintering temperature is 400-700° C. to obtain a lithium-containing iron phosphate precursor.

[0029] The embodiment of the present application also provides a lithium iron phosphate precursor, which is prepared by the lithium iron phosphate precursor preparation method described in the above embodiment.

[0030] The embodiment of the present application provides a lithium iron phosphate, which is manufactured by sintering the lithium iron phosphate precursor described in the above embodiment.

[0031] The present application provides a method for preparing a lithium iron phosphate precursor, which includes mixing waste lithium iron phosphate battery powder with pure water, adding an oxidant and hydrochloric acid for acid leaching, filtering to obtain an acid leaching solution and an acid leaching residue; adding the acid leaching solution to waste lithium iron phosphate battery powder and an oxidant to adjust the pH value to obtain a lithium-containing solution; washing and acid leaching the acid leaching residue to obtain a phosphorus-iron acid leaching solution containing phosphorus and iron; removing impurities from the phosphorus-iron acid leaching solution to obtain an impurity-removing liquid; mixing the lithium-containing solution and the impurity-removing liquid to obtain a lithium-containing phosphorus-iron solution; spray pyrolysis of the lithium-containing phosphorus-iron solution to obtain a lithium-containing iron phosphate precursor. By directly processing waste battery powder, the step of preparing intermediate products in the traditional method is avoided, thereby reducing costs. At the same time, by precisely controlling the reaction conditions of each step, the introduction of impurities is minimized, ensuring the high purity of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0033] Figure 1 A schematic flow chart of a method for preparing a lithium iron phosphate precursor provided in an embodiment of the present application.

[0034] Figure 2 This is an electron microscope image of the lithium iron phosphate precursor provided in the embodiment of the present application.

[0035] Figure 3 Another electron microscope image of the lithium iron phosphate precursor provided in the embodiment of the present application.

[0036] Figure 4 This is an electron microscope image of lithium iron phosphate provided in the embodiment of the present application. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0038] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0039] The embodiments of the present application provide a method for preparing a lithium-containing iron phosphate precursor, a lithium-containing iron phosphate precursor, and lithium iron phosphate.

[0040] See also Figure 1 , Figure 1 A schematic flow chart of a method for preparing a lithium iron phosphate precursor is provided. The present application provides a method for preparing a lithium iron phosphate precursor, comprising the following steps:

[0041] S10 mixes waste lithium iron phosphate battery powder with pure water, adds oxidant and hydrochloric acid for acid leaching, and obtains acid leaching liquid and acid leaching residue after filtering.

[0042] It should be noted that the source of waste lithium iron phosphate battery powder is mainly waste lithium iron phosphate batteries. After these batteries are used in electric vehicles, energy storage systems and other fields, they are disassembled and recycled to obtain battery powder. Among them, waste lithium iron phosphate battery powder mainly contains lithium iron phosphate, which is the main component of battery positive electrode materials. It is an olivine structure compound, in which lithium (Li) is a valuable metal element that needs to be extracted and utilized.

[0043] Among them, part of the divalent iron can be oxidized to trivalent iron by an oxidant, which is helpful for the subsequent separation process. Different oxidants have different redox potentials and reactivity. For example, hydrogen peroxide (hydrogen peroxide) is a commonly used oxidant, which can effectively oxidize low-valent metal ions in battery powder to high-valent states under acidic conditions, which is conducive to the subsequent dissolution process. Hydrochloric acid provides an acidic environment to promote the dissolution of elements such as lithium, iron, and phosphorus. By controlling the pH value, the target element can be selectively dissolved. Hydrochloric acid plays a role in dissolving metal compounds during acid leaching. Lower concentrations of hydrochloric acid may not be able to completely dissolve lithium-containing compounds and other impurities, resulting in a low lithium extraction rate. Although higher concentrations of hydrochloric acid can increase the dissolution rate, it may bring about problems such as equipment corrosion, and may dissolve some unwanted impurities, increasing the difficulty of subsequent impurity removal. The hydrochloric acid concentration of the present application is 2-8mol / L. After acid leaching, the acid leaching solution and the acid leaching residue are obtained by filtration and separation. The acid leaching solution mainly contains dissolved lithium ions, while some iron and phosphorus still remain in the acid leaching residue.

[0044] S20: adding the acid leaching solution to waste lithium iron phosphate battery powder and hydrogen peroxide to adjust the pH value to obtain a lithium-containing solution.

[0045] It should be noted that when the acid leaching solution is added to the waste lithium iron phosphate battery powder and hydrogen peroxide, multiple chemical reactions are involved. First, the acid leaching solution contains acidic substances such as hydrochloric acid, which will continue to react with components such as lithium iron phosphate in the battery powder. This reaction will cause lithium to enter the solution in the form of lithium chloride (LiCl). The addition of hydrogen peroxide mainly plays an oxidizing role. In an acidic environment, it can oxidize ferrous ions into ferric ions. The hydrolysis of ferric ions will affect the pH value of the solution, and its hydrolysis equation is 2Fe 2 +H2O2+2H + =2Fe 3 +2H2O, this process will release hydrogen ions, which will lower the pH value of the solution. Adjusting the pH value is a key step, allowing lithium to exist in the solution in a relatively stable form, and finally obtaining a lithium-containing solution. The pH value has an important influence on the existence form of lithium in the solution. At a lower pH value, lithium mainly exists in the form of lithium ions, which is conducive to the extraction and subsequent treatment of lithium. If the pH value is too high, lithium may form a precipitate, such as lithium hydroxide precipitation, and its reaction equation is. Precipitation and dissolution of other impurities: The appropriate pH value can also affect the behavior of other impurities. For example, when the pH value increases, iron ions will gradually form iron hydroxide precipitates and be removed. In this way, the separation of lithium from other impurities can be achieved by adjusting the pH value, thereby improving the purity of the lithium-containing solution.

[0046] S30: washing and acid leaching the acid leaching residue to obtain a ferrophosphorus acid leaching solution containing phosphorus and iron.

[0047] It should be noted that washing the acid leaching residue is mainly to remove the acid leaching solution and some soluble impurities remaining on the surface of the acid leaching residue. These residual substances may interfere with the subsequent acid leaching process. For example, if there are more chlorides of other metal ions remaining, they may be mixed into the ferrophosphorus acid leaching solution during the second acid leaching, affecting its purity.

[0048] Among them, the acid leaching residue mainly contains incompletely dissolved phosphorus and iron compounds, such as iron phosphate. The purpose of the second acid leaching is to dissolve these phosphorus and iron compounds and make them enter the solution to form ferrophosphate acid leaching solution. In an acidic environment, according to the principle of chemical reaction equilibrium, the hydrogen ions in the acid will react with compounds such as iron phosphate to promote their dissolution.

[0049] S40 removes impurities from the ferrophosphorus acid leaching solution to obtain an impurity-removed liquid.

[0050] It should be noted that impurity removal can remove impurity ions in the ferrophosphide acid leaching solution and improve the purity of the final product. Specifically, this step mainly removes aluminum, fluorine, etc. in the ferrophosphide acid leaching solution.

[0051] S50: mixing the lithium-containing solution and the impurity removal solution to obtain a lithium-containing ferrophosphorus solution.

[0052] It should be noted that the purified lithium-containing solution and the impurity-removed ferrophosphorus solution are mixed to obtain a lithium-containing ferrophosphorus solution. The key to this step is to control the mixing ratio to ensure that the molar ratio of lithium, iron and phosphorus in the final solution meets the requirements.

[0053] S60 sprays and pyrolyzes the lithium-containing iron-phosphorus solution to obtain a lithium-containing iron-phosphate precursor.

[0054] It should be noted that the mixed lithium iron phosphate solution is processed by a spray pyrolysis device. Under high temperature conditions, the solution is atomized into tiny droplets, which evaporate, decompose and react quickly to form solid particles, namely, lithium iron phosphate precursor.

[0055] The method of the embodiment of the present application directly processes waste battery powder, avoiding the step of preparing intermediate products in the traditional method, thereby reducing costs. At the same time, by accurately controlling the reaction conditions of each step, the introduction of impurities is minimized, ensuring the high purity of the final product. In addition, the spray pyrolysis method can obtain precursor particles with uniform particle size and good dispersibility, laying the foundation for the subsequent preparation of high-performance lithium iron phosphate materials.

[0056] In some embodiments, the waste lithium iron phosphate powder is mixed with pure water, hydrogen peroxide and hydrochloric acid are added for acid leaching, and the acid leaching liquid and acid leaching residue are obtained after filtering, which comprises:

[0057] S11: mixing waste lithium iron phosphate battery powder with pure water into a slurry, adding an oxidant dropwise to the slurry and then adding hydrochloric acid to adjust the pH value to 4.5 to 5, and obtaining a primary acid leaching solution and a primary acid leaching residue after solid-liquid separation.

[0058] S12: adding pure water and hydrochloric acid to the primary acid leaching residue to adjust the pH value to 1 to 2, and filtering to obtain a secondary acid leaching solution and secondary acid leaching residue.

[0059] It should be noted that this two-step acid leaching method can effectively improve the efficiency and integrity of acid leaching. In the first step, by adjusting the pH value to 4.5 to 5, most of the lithium and part of the iron can be initially dissolved while maintaining the stability of the phosphate ions. In the second step, by lowering the pH value to 1 to 2, the residual iron and phosphorus can be further dissolved, thereby maximizing the recovery rate.

[0060] Through this two-step acid leaching method, the present application can effectively improve the recovery rate of lithium, iron and phosphorus. Compared with the traditional single-step acid leaching, this method can make more full use of the valuable elements in the waste battery powder. At the same time, since excessive acidic conditions are avoided, corrosion to equipment and environmental impact can also be reduced.

[0061] Furthermore, the present application further proposes a more accurate acid leaching process control method. Specifically, waste lithium iron phosphate battery powder is mixed with pure water in a ratio of 1 to 5 to form a slurry, an oxidant and hydrochloric acid are slowly added to the slurry to adjust the pH value to 4.5 to 5, and stirred at 50-65°C for 4-8 hours, and a primary acid leaching liquid and a primary acid leaching residue are obtained after solid-liquid separation. Then, pure water and hydrochloric acid are added to the primary acid leaching residue to adjust the pH value to 1 to 2, and stirred at 55-65°C for 6-8 hours, and filtered to obtain a secondary acid leaching liquid and a secondary acid leaching residue.

[0062] This improved acid leaching process control method can effectively improve the acid leaching efficiency and product quality by precisely controlling the reaction conditions. Specifically, the present application achieves precise control of the acid leaching process through the following aspects:

[0063] First, this application stipulates that the mixing ratio of waste lithium iron phosphate battery powder and pure water is 1:5. This ratio is selected after multiple experimental optimizations to ensure that the slurry has appropriate fluidity and reactivity. A ratio that is too low will cause the slurry to be too thick, affecting the uniformity of the reaction; a ratio that is too high will reduce the reaction efficiency and increase the difficulty of subsequent processing.

[0064] Secondly, the present application precisely controls the pH value of the primary acid leaching and adjusts it to a range of 4.5 to 5. This pH range is carefully selected to ensure that lithium is fully dissolved while minimizing the dissolution of iron and phosphorus. A pH value below 4.5 will cause excessive dissolution of iron and phosphorus, increasing the difficulty of subsequent separation; while a pH value above 5 will reduce the efficiency of lithium dissolution.

[0065] Again, the present application stipulates that the temperature range of the first acid leaching is 50-65°C and the stirring time is 4-8h. This temperature range can accelerate the reaction rate without causing excessive energy consumption or increased equipment corrosion. The choice of stirring time balances the reaction sufficiency and production efficiency.

[0066] For the secondary acid leaching, the present application further reduces the pH value to 1 to 2 in order to dissolve the residual valuable metals to the greatest extent. At the same time, the temperature is slightly increased to 55-65°C and the stirring time is extended to 6-8h to ensure sufficient reaction.

[0067] Through this precisely controlled acid leaching process, the lithium leaching rate can be significantly improved while minimizing the loss of iron and phosphorus. Compared with the traditional acid leaching method, the method of the present application can increase the lithium leaching rate by about 10-15% while reducing the loss of iron and phosphorus by about 20-30%. This not only improves the efficiency of resource utilization, but also reduces the difficulty and cost of subsequent separation and purification.

[0068] In addition, the method of the present application has the advantages of simple operation and low energy consumption. By precisely controlling the reaction conditions, efficient leaching can be achieved at a lower temperature, reducing energy consumption. At the same time, due to the mild reaction conditions, the degree of equipment corrosion is low, which can extend the service life of the equipment and reduce maintenance costs.

[0069] The present application further proposes the specific selection and dosage ratio of the oxidant. The present application provides a variety of oxidant options, including hydrogen peroxide, oxygen, ozone and sodium persulfate. These oxidants have different oxidizing abilities and characteristics and can be selected according to specific needs. Among them, hydrogen peroxide, as a commonly used oxidant, has the characteristics of simple operation and mild reaction.

[0070] Specifically, when hydrogen peroxide is selected as the oxidant, the mass ratio of waste lithium iron phosphate battery powder to hydrogen peroxide is about 1:0.4-0.8, and the mass ratio to hydrochloric acid is about 1:0.2-0.3. This ratio is optimized to ensure the full progress of the reaction while avoiding waste caused by excessive use of reagents.

[0071] The selection and dosage of oxidants are crucial to the acid leaching process. Appropriate oxidants can promote the dissolution of lithium, iron, and phosphorus in lithium iron phosphate and improve the leaching efficiency. For example, hydrogen peroxide can oxidize divalent iron to trivalent iron, which is conducive to the dissolution of iron. At the same time, the presence of oxidants can also prevent the reduction and precipitation of certain metal ions and maintain the stability of the solution.

[0072] Furthermore, the action mechanisms of different oxidants are slightly different. Hydrogen peroxide can produce hydroxyl radicals under acidic conditions and has strong oxidizing properties; oxygen can be introduced into the reaction system by bubbling to provide a continuous oxidizing environment; ozone has stronger oxidizing properties, but requires special equipment to generate; sodium persulfate can decompose at higher temperatures to produce sulfate radicals, which also has strong oxidizing ability.

[0073] Therefore, by properly selecting the oxidant and its dosage, the efficiency and selectivity of the acid leaching process can be significantly improved. Taking hydrogen peroxide as an example, a mass ratio of 1:0.4-0.8 can ensure that there is enough oxidant to participate in the reaction without excessive side reactions or waste. At the same time, a mass ratio of 1:0.2-0.3 with hydrochloric acid can provide a suitable acidic environment to promote the dissolution of metal ions.

[0074] In some embodiments, the step of adding the acid leaching solution to waste lithium iron phosphate battery powder and hydrogen peroxide to adjust the pH value to obtain a lithium-containing solution comprises:

[0075] Continue to add the acid leaching liquid into the waste lithium iron phosphate battery powder and stir, and slowly add hydrogen peroxide to the solution at the same time, adjust the pH value to 6-8, and the ratio of waste lithium iron phosphate battery powder to solution used for adjusting the pH value is about 1:10-15. Stir for 30min-2h at a temperature of 50-60℃, add the defluorination agent, stir for 1-2h at room temperature, and then separate the solid and liquid to obtain a lithium-containing solution.

[0076] It should be noted that this method increases the concentration of lithium ions by adding waste lithium iron phosphate battery powder and hydrogen peroxide to the acid leaching solution. Specifically, waste lithium iron phosphate battery powder, as a lithium source, can further release lithium ions into the solution under the oxidation of hydrogen peroxide. At the same time, by adjusting the pH value to a weakly alkaline environment of 6-8, the dissolution of lithium ions can be promoted without causing the precipitation of other metal ions.

[0077] In this process, the ratio of waste lithium iron phosphate battery powder to solution is about 1:10-15, which is optimized. This ratio can ensure sufficient lithium source supply, while not causing the solution to be too thick, affecting subsequent separation and processing. The temperature is controlled at 50-60℃, which can accelerate the reaction speed, but will not be too high to cause the water in the solution to evaporate too quickly. The stirring time is 30min-2h, which can ensure that the reaction is fully carried out, but will not be too long to affect production efficiency.

[0078] This method can effectively increase the concentration of lithium ions in the acid leaching solution, providing higher quality raw materials for the subsequent preparation of lithium iron phosphate precursors. At the same time, this method can also make full use of the lithium resources in waste lithium iron phosphate battery powder and improve resource utilization.

[0079] As a preferred implementation, the following specific steps can be adopted: 1. Place the acid leaching solution in a reactor and add waste lithium iron phosphate battery powder. The mass ratio of waste lithium iron phosphate battery powder to the acid leaching solution is 1:12. 2. Turn on the agitator and set the stirring speed to 200rpm. 3. Slowly drip a 30% concentration of hydrogen peroxide solution while monitoring the pH value of the solution. 4. When the pH value reaches 7.5, stop dripping hydrogen peroxide. 5. Adjust the temperature of the reactor to 55°C and continue stirring for 1.5 hours. 6. Stop stirring, pass the solution through a centrifuge for solid-liquid separation, add a defluorinating agent, stir at room temperature for 1-2 hours, and then separate the solid and liquid to obtain a lithium-containing solution.

[0080] Compared with the traditional acid leaching method, this method has the following advantages: 1. Increased lithium ion concentration: By adding waste lithium iron phosphate battery powder and hydrogen peroxide, lithium ions can be further released to increase the concentration of lithium ions in the solution. 2. Reduced impurity content: By controlling the pH value within the range of 6-8, the dissolution of other metal ions can be effectively inhibited and the impurity content in the solution can be reduced. 3. Improved resource utilization: Fully utilize the lithium resources in waste lithium iron phosphate battery powder and reduce resource waste. 4. Simple operation and easy control: By controlling parameters such as temperature, time and pH value, precise control of the process can be easily achieved.

[0081] Through this method, a lithium-containing solution with higher lithium ion concentration and lower impurity content can be obtained, which provides better raw materials for the subsequent preparation of lithium-containing iron phosphate precursors, thereby improving the quality and performance of the final product.

[0082] In some embodiments, washing and acid leaching the acid leaching residue to obtain a ferrophosphorus acid leaching solution containing phosphorus and iron comprises:

[0083] S31: adding the acid leaching residue into pure water at a liquid-to-solid ratio of about 3-5:1, stirring and slurrying, adding hydrochloric acid to adjust the pH value of the slurry to 1-2, and raising the temperature to 50-70°C, and continuously stirring for 1-2h to obtain ferrophosphorus slag with low nickel, cobalt and manganese content.

[0084] S32: Add pure water to the ferrophosphorus slag with low nickel, cobalt and manganese content at a solid-liquid ratio of 1:5, stir and slurry, then add hydrochloric acid and iron powder, stir for 5-6 hours, and then filter to obtain the ferrophosphorus acid leaching solution containing phosphorus and iron.

[0085] It should be noted that the two-stage treatment process is designed to maximize the recovery of valuable metals, especially phosphorus and iron, from the acid leaching residue. These metals can be effectively leached from the residue by adjusting the pH value, temperature and stirring time. The step of adding iron powder helps to reduce some of the insoluble phosphates, further improving the recovery rate of phosphorus.

[0086] Compared with the prior art, the technical solution of the present application has the following advantages:

[0087] First, the two-stage treatment greatly improves the recovery rate of phosphorus and iron. The first stage of treatment can remove most impurities and obtain ferrophosphorus slag with low nickel, cobalt and manganese content. The second stage of treatment further improves the leaching efficiency of phosphorus and iron.

[0088] Secondly, the leaching process can be better controlled by adjusting the pH value in stages. In the first stage, the strong acidic condition with a pH value of 1-2 is conducive to the removal of impurities. In the second stage, the addition of iron powder helps to reduce some of the insoluble phosphates, further improving the recovery rate of phosphorus.

[0089] Again, temperature control and appropriate stirring time ensure that the reaction proceeds fully. The temperature range of 5070℃ and stirring time of 12 hours provide suitable conditions for the first stage reaction, while the stirring time of 5-6 hours in the second stage ensures sufficient leaching of phosphorus and iron.

[0090] Finally, this method not only improves resource utilization, but also reduces the generation of waste slag, which has good environmental benefits.

[0091] In some embodiments, removing impurities from the ferrophosphide acid leaching solution to obtain a de-impurity liquid comprises: adding an aluminum removal agent to the ferrophosphide acid leaching solution, stirring for 1-2 hours at room temperature and then filtering, then adding a fluorine removal agent, and continuing to stir for 1-2 hours to obtain the de-impurity liquid.

[0092] It should be noted that the aluminum removal agent can be a fluoride, such as sodium fluoride, lithium fluoride, etc., and the defluorination agent is any one of the corresponding oxides or carbonates of lanthanum, cerium, praseodymium, neodymium, promethium, etc. The technical solution proposed in this application can effectively remove the impurity elements in the solution and improve the purity of the final product by adding an aluminum removal agent and a defluorination agent to the ferrophosphide acid leaching solution for impurity removal. This impurity removal method is simple and effective, easy to operate, can be carried out at room temperature, and does not require complex equipment and high-energy consumption processing.

[0093] Specifically, the impurity removal process of the present application includes two main steps: first, lithium fluoride is added to the ferrophosphide acid leaching solution, and the solution is filtered after stirring for 1-2 hours at room temperature; then, a defluorinating agent is added to the filtered solution, and stirring is continued for 1-2 hours. The sequential design of these two steps is carefully considered, and different types of impurity elements can be gradually removed. The combined use of the two impurity removers can achieve a more comprehensive impurity removal effect.

[0094] The stirring time is set to 1-2 hours to ensure that the reaction proceeds fully without excessively extending the processing time. Operating at room temperature can reduce energy consumption and simplify the process. The setting of the filtration step can effectively separate the precipitate and the solution and improve the impurity removal efficiency.

[0095] Through this impurity removal treatment, the impurity content in the ferrophosphate acid leaching solution can be significantly reduced, providing a purer raw material for the subsequent preparation of lithium-containing iron phosphate precursors. This not only helps to improve the quality of the final product, but also reduces the impurity interference problems that may occur in subsequent processes.

[0096] As a preferred embodiment, the amount of aluminum removal agent and fluorine removal agent added can be adjusted according to actual conditions. For example, the amount of impurity removal agent can be determined according to the type and content of impurity elements by analyzing the components of the ferrophosphate acid leaching solution in advance. Usually, the amount of aluminum removal agent added can be 0.5-2% of the weight of the ferrophosphate acid leaching solution, and the amount of fluorine removal agent added can be 0.1-1%.

[0097] In actual operation, the following specific steps can be used for impurity removal: 1. Prepare 1000mL of ferrophosphide acid leaching solution and place it in a reaction vessel with a stirring device. 2. Slowly add 10g of aluminum removal agent powder to the ferrophosphide acid leaching solution, turn on the stirring device, and stir at room temperature for 1.5 hours. 3. Stop stirring and vacuum filter the mixed solution through a 0.45μm filter membrane. 4. Add 5g of fluorine removal agent powder to the filtrate, turn on the stirring device again, and continue stirring at room temperature for 1.5 hours. 5. Stop stirring to obtain the de-impurified solution.

[0098] The impurity content of the ferrophosphate acid leaching solution treated by this method can be reduced by more than 80%, providing high-purity raw materials for the subsequent preparation of lithium iron phosphate precursors. The application of this impurity removal method can not only improve the purity of lithium iron phosphate precursors, but also extend the service life of subsequent equipment and reduce equipment corrosion and blockage problems caused by impurities. At the same time, high-purity raw materials also lay the foundation for the production of high-performance lithium iron phosphate battery materials, which helps to improve the electrochemical performance and cycle life of the final product.

[0099] In some embodiments, mixing the lithium-containing solution and the impurity removal solution to obtain a lithium-phosphorus-iron solution includes: adjusting the phosphorus-iron ratio in the lithium-phosphorus-iron solution, wherein the molar ratio of iron to phosphorus in the lithium-phosphorus-iron solution is (0.95-1.00):1.

[0100] It should be noted that the present application first adjusts the iron-phosphorus ratio in the lithium-phosphorus-iron solution. The iron:phosphorus molar ratio is controlled within the range of (0.95-1.00):1. This ratio range can ensure the accuracy of the iron-phosphorus ratio in the final product and is conducive to forming an ideal crystal structure. For example, the ratio can be adjusted by adding an appropriate amount of iron salt or phosphate.

[0101] In some embodiments, the step of spray pyrolyzing the lithium iron phosphate solution to obtain a lithium iron phosphate precursor comprises:

[0102] S61: Concentrating the lithium-phosphorus-iron solution to obtain a concentrated solution.

[0103] The concentration step can be achieved by various methods, such as heating evaporation, reduced pressure evaporation or membrane concentration, etc. The degree of concentration can be adjusted according to actual needs, and the solution can usually be concentrated to 1 / 2 to 1 / 5 of the original volume.

[0104] S62 atomizes the concentrated liquid to obtain atomized liquid droplets.

[0105] The atomization process can use pressure atomization, centrifugal atomization or ultrasonic atomization to obtain droplets with uniform particle size and stable distribution. The size of the atomized droplets has an important influence on the performance of the final product and is generally controlled within the range of 10-100 microns.

[0106] S63: sintering the atomized liquid droplets from top to bottom in a synthesis furnace under the action of gravity, with the sintering temperature being 400-700° C. to obtain a lithium iron phosphate precursor.

[0107] Among them, the sintering process is the key step of this technical solution. The design of the synthesis furnace needs to consider the uniformity of the temperature distribution. A multi-stage heating method can be adopted to allow the droplets to undergo preheating, reaction and cooling stages during the falling process. The selection of sintering temperature requires a balance between the reaction rate and product quality. Temperatures below 400°C may lead to incomplete reactions, while temperatures above 700°C may cause changes in the crystal form or agglomeration of the product. Therefore, the present application selects a temperature range of 400 to 700°C, which can ensure sufficient reaction while obtaining a lithium iron phosphate precursor with stable structure and good dispersion.

[0108] It should be noted that the lithium-phosphorus-iron solution with a good ratio is concentrated. The concentration process can be carried out by evaporation, reduced pressure distillation and other methods, the purpose of which is to increase the concentration of the effective ingredients in the solution and prepare for the subsequent atomization and sintering process. The degree of concentration can be adjusted according to actual needs, for example, it can be concentrated to a solid content of 20-30% in the solution.

[0109] The concentrated solution is atomized. Atomization can be performed by pressure atomization, centrifugal atomization or ultrasonic atomization to convert the concentrated solution into fine droplets. The size of the droplets directly affects the particle size and morphology of the final product, so the atomization parameters need to be precisely controlled. For example, the atomization pressure can be controlled at 25MPa and the atomization nozzle diameter can be controlled at 0.10.5mm.

[0110] The atomized droplets enter the synthesis furnace under the action of gravity for sintering. The sintering temperature is controlled in the range of 400700℃, which can ensure that the precursor is fully crystallized without over-sintering. The sintering time can be adjusted according to actual conditions, usually between 5-30 minutes. During the sintering process, inert gases such as nitrogen or argon can be introduced into the furnace to prevent the precursor from being oxidized. The lithium iron phosphate precursor prepared by this method has a good stoichiometric ratio and uniform particle distribution. Due to the precise control of the iron-phosphorus ratio and sintering conditions, the resulting precursor has high crystallinity and regular morphology, which is conducive to the subsequent preparation of high-performance lithium iron phosphate materials.

[0111] The present application also provides a specific embodiment, which is as follows:

[0112] Weigh 100 kg of waste lithium iron phosphate battery powder, add 500 kg of pure water, and mix thoroughly in a blender to form a uniform slurry.

[0113] Slowly add 60 kg of 30% hydrogen peroxide solution to the slurry, and at the same time slowly add 25 kg of 36% hydrochloric acid, and control the addition speed to stabilize the pH value between 4.7-4.8.

[0114] The reaction temperature was adjusted to 58°C, and the stirrer was started and stirred at 200 rpm for 6 hours.

[0115] Stop stirring, and separate the reaction liquid into solid and liquid by centrifuge to obtain primary acid leaching liquid and primary acid leaching residue.

[0116] Add 300 kg of pure water to the acid leaching residue, stir evenly, then add 40 kg of 36% hydrochloric acid, and adjust the pH value to 1.5.

[0117] The reaction temperature was raised to 60°C and stirred at 180 rpm for 7 hours.

[0118] After the reaction is completed, solid-liquid separation is performed by a filter press to obtain secondary acid leaching liquid and secondary acid leaching residue.

[0119] The secondary acid leaching liquid is placed in a reaction kettle, and waste lithium iron phosphate battery powder is added, wherein the mass ratio of waste lithium iron phosphate battery powder to the secondary acid leaching liquid is 1:12.

[0120] Turn on the stirrer and set the stirring speed to 200 rpm.

[0121] Slowly add 30% hydrogen peroxide solution while monitoring the pH value of the solution.

[0122] When the pH value reaches 7.5, stop adding hydrogen peroxide.

[0123] The temperature of the reactor was adjusted to 55°C and stirring was continued for 1.5 hours.

[0124] Stop stirring, and use a centrifuge to separate the solution into solid and liquid to obtain a lithium-containing solution.

[0125] The secondary acid leaching residue is mixed with pure water at a liquid-solid ratio of 4:1 and stirred evenly to form a slurry. Then, hydrochloric acid with a concentration of 36% is slowly added until the pH value of the slurry drops to 1.5. The temperature is raised to 60°C and stirred continuously at this temperature for 1.5 hours. By filtering and separating, a ferrophosphorus slag with low nickel, cobalt and manganese content is obtained.

[0126] Next, the above ferrophosphorus slag was mixed with pure water at a solid-liquid ratio of 1:5. 50 mL of 36% hydrochloric acid and 10 g of reduced iron powder (assuming that 100 g of ferrophosphorus slag was processed) were added to the mixture. After stirring at room temperature for 5.5 hours, a ferrophosphorus acid leaching solution containing phosphorus and iron was obtained by filtration.

[0127] The ferrophosphorus acid leaching solution containing phosphorus and iron is placed in a reaction container with a stirring device.

[0128] Slowly add aluminum removal agent powder to the ferrophosphide acid leaching solution, turn on the stirring device, and stir at room temperature for 1.5 hours.

[0129] Stop stirring and filter the mixture through a 0.45 μm filter membrane by vacuum filtration.

[0130] Add defluorinating agent powder to the filtrate, turn on the stirring device again, and continue stirring at room temperature for 1.5 hours.

[0131] Stop stirring to obtain a solution after impurities are removed.

[0132] The molar ratio of iron to phosphorus in the lithium-phosphorus-iron solution was adjusted to 0.98:1.

[0133] Then, the solution was concentrated to a solid content of 25% using a rotary evaporator.

[0134] Next, a pressure atomizer was used, the atomization pressure was set to 3 MPa, and the nozzle diameter was set to 0.3 mm for atomization. Finally, the atomized droplets were sent to a spray pyrolysis furnace, the furnace temperature was set to 550°C, nitrogen was introduced, and the sintering time was 500°C to obtain a lithium iron phosphate precursor.

[0135] By directly processing waste battery powder, the steps of preparing intermediate products in traditional methods are avoided, thereby reducing costs. At the same time, by precisely controlling the reaction conditions of each step, the introduction of impurities is minimized, ensuring the high purity of the final product. In addition, the spray pyrolysis method can obtain precursor particles with uniform particle size and good dispersibility, laying the foundation for the subsequent preparation of high-performance lithium iron phosphate materials.

[0136] See also Figure 2 and Figure 3 The present application also provides a lithium iron phosphate precursor, which is prepared by the lithium iron phosphate precursor preparation method described in the above embodiment. Since the lithium iron phosphate precursor preparation method has been described in detail in the above embodiment, it will not be described in detail in the present application.

[0137] Since the lithium iron phosphate precursor is directly processed from waste battery powder, the steps of preparing intermediate products in the traditional method are avoided, thereby reducing costs. At the same time, by precisely controlling the reaction conditions of each step, the introduction of impurities is minimized, ensuring the high purity of the final product. In addition, the spray pyrolysis method can obtain precursor particles with uniform particle size and good dispersibility.

[0138] See also Figure 4 The application embodiment provides a lithium iron phosphate, which is made by sintering the lithium iron phosphate precursor described in the above embodiment.

[0139] A lithium iron phosphate precursor, anhydrous glucose (Xiwang Group, GB / T20880), and PEG 1500 (Sinopharm Chemical Reagent Co., Ltd., Q / CYDZ2317-2009) are mixed together and added into pure water and stirred for 30 minutes until all the raw materials are evenly mixed and in a slurry state. The slurry is then spray-dried at 180°C, and the obtained dry powder is sintered in an atmosphere furnace under nitrogen atmosphere protection. The temperature is evenly raised from room temperature to 750°C in 4 hours, sintered for 8 hours, and cooled to room temperature under nitrogen atmosphere protection to obtain carbon-coated lithium iron phosphate. The obtained carbon-coated lithium iron phosphate is crushed by an air flow mill, and the crushed material is lithium iron phosphate.

[0140] The above is a detailed introduction to the preparation method of the lithium iron phosphate precursor, the lithium iron phosphate precursor and the lithium iron phosphate provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a lithium iron phosphate precursor, characterized in that: include: Mix the waste lithium iron phosphate battery powder with pure water, add oxidant and hydrochloric acid for acid leaching, After filtering, the acid leaching liquid and the acid leaching residue are obtained; Adding the acid leaching solution to waste lithium iron phosphate battery powder and hydrogen peroxide to adjust the pH value to obtain a lithium-containing solution; The acid leaching residue is washed and acid-leached to obtain a ferrophosphorus acid leaching solution containing phosphorus and iron; The ferrophosphorus acid leaching solution is subjected to impurity removal to obtain an impurity-removed liquid; The lithium-containing solution and the impurity-removing liquid are mixed to obtain a lithium-containing ferrophosphorus solution; The lithium-containing iron-phosphorus solution is spray-pyrolyzed to obtain a lithium-containing iron-phosphate precursor.

2. The method for preparing a lithium iron phosphate precursor according to claim 1, characterized in that: The waste lithium iron phosphate powder is mixed with pure water, an oxidant and hydrochloric acid are added for acid leaching, and the acid leaching liquid and acid leaching residue are obtained after filtering, which comprises: Mixing waste lithium iron phosphate battery powder with pure water into a slurry, adding an oxidant dropwise to the slurry and then adding hydrochloric acid to adjust the pH value to 4.5 to 5, and obtaining a primary acid leaching solution and a primary acid leaching residue after solid-liquid separation; The primary acid leaching residue is added with pure water and hydrochloric acid to adjust the pH value to 1 to 2, and filtered to obtain a secondary acid leaching solution and secondary acid leaching residue.

3. The method for preparing a lithium iron phosphate precursor according to claim 2, characterized in that: The waste lithium iron phosphate battery powder is mixed with pure water to form a slurry, an oxidant is added to the slurry, and then hydrochloric acid is added to adjust the pH value to 4.5 to 5, and a primary acid leaching solution and a primary acid leaching residue are obtained after solid-liquid separation. The waste lithium iron phosphate battery powder and pure water are mixed into a slurry at a ratio of 1 to 5, an oxidant and hydrochloric acid are slowly added to the slurry to adjust the pH value to 4.5 to 5, and stirred at 50-65° C. for 4-8 hours, and a primary acid leaching solution and a primary acid leaching residue are obtained after solid-liquid separation; The step of adding pure water and hydrochloric acid to the primary acid leaching residue to adjust the pH value to 1 to 2, and filtering to obtain a secondary acid leaching solution and secondary acid leaching residue comprises: The primary acid leaching residue is added with pure water and hydrochloric acid to adjust the pH value to 1 to 2, and stirred at 55-65° C. for 6-8 hours, and filtered to obtain a secondary acid leaching solution and secondary acid leaching residue.

4. The method for preparing a lithium iron phosphate precursor according to claim 3, characterized in that: The oxidant is any one of hydrogen peroxide, oxygen, ozone, and sodium persulfate. When the oxidant is hydrogen peroxide, the mass ratio of the waste lithium iron phosphate battery powder to hydrogen peroxide is about 1:0.4-0.8, and the mass ratio to hydrochloric acid is about 1:0.2-0.

3.

5. The method for preparing a lithium iron phosphate precursor according to claim 1, characterized in that: The step of adding the acid leaching solution to waste lithium iron phosphate battery powder and hydrogen peroxide to adjust the pH value to obtain a lithium-containing solution comprises: Add the acid leaching solution into the waste lithium iron phosphate battery powder and stir, and slowly add hydrogen peroxide to the solution to adjust the pH value to 6-8. The ratio of waste lithium iron phosphate battery powder to solution used for adjusting the pH value is about 1:10-15. After stirring at 50-60°C for 30min-2h, add the defluorination agent, stir at room temperature for 1-2h for solid-liquid separation to obtain a lithium-containing solution.

6. The method for preparing a lithium iron phosphate precursor according to claim 1, characterized in that: The washing and acid leaching of the acid leaching residue to obtain a phosphorus-containing ferrophosphorus acid leaching solution comprises: The acid leaching residue is added with pure water at a liquid-to-solid ratio of about 3 to 5:1, stirred and slurried, hydrochloric acid is added to adjust the pH value of the slurry to 1-2, and the temperature is raised to 50 to 70° C., and stirring is continued for 1 to 2 hours to obtain ferrophosphorus slag with low nickel, cobalt and manganese content; Add pure water to the ferrophosphorus slag with low nickel, cobalt and manganese content at a solid-liquid ratio of 1:5, stir and slurry, then add hydrochloric acid and iron powder, stir for 5-6 hours, and then filter to obtain the ferrophosphorus acid leaching solution containing phosphorus and iron.

7. The method for preparing a lithium iron phosphate precursor according to claim 1, characterized in that: The step of removing impurities from the ferrophosphorus acid leaching solution to obtain the impurity-removed liquid comprises: Add an aluminum remover to the ferrophosphide acid leaching solution, stir for 1-2 hours at room temperature, filter, then add a fluorine remover, continue stirring for 1-2 hours, and obtain a decontamination solution.

8. The method for preparing a lithium iron phosphate precursor according to claim 1, characterized in that: Mixing the lithium-containing solution and the impurity-removing liquid to obtain a lithium-containing ferrophosphorus solution comprises: The phosphorus-iron ratio in the lithium-phosphorus-iron solution is adjusted, wherein the molar ratio of iron to phosphorus in the lithium-phosphorus-iron solution is (0.95-1.00):1; The step of spraying pyrolysis of the lithium-containing iron phosphate solution to obtain a lithium-containing iron phosphate precursor comprises: Concentrating the lithium-phosphorus-iron solution to obtain a concentrated solution; atomizing the concentrated liquid to obtain atomized liquid droplets; The atomized liquid droplets are sintered from top to bottom in a synthesis furnace under the action of gravity, and the sintering temperature is 400-700° C. to obtain a lithium-containing iron phosphate precursor.

9. A lithium iron phosphate precursor, characterized in that: The lithium iron phosphate precursor is prepared by the method for preparing the lithium iron phosphate precursor according to any one of claims 1 to 8.

10. A lithium iron phosphate, characterized in that: It is made by sintering the lithium iron phosphate precursor as claimed in claim 9.

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