KR20200115338A - Method for purifying waste lithium phosphate and method for manufacturing lithium iron phosphate comprising the same - Google Patents

Abstract

The present invention relates to a method for purifying waste lithium phosphate (Li_3PO_4) extracted from a waste lithium battery. The present invention provides the method for purifying waste lithium phosphate comprising the steps of: (a) preparing a first mixture by mixing the waste lithium phosphate and water; (b) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; and (c) preparing purified lithium phosphate by separating the impurities and water from the second mixture. The method for purifying waste lithium phosphate and a method for preparing lithium iron phosphate according to the present invention has an effect of purifying waste lithium phosphate (Li_3PO_4) extracted from a waste lithium battery with high purity at a simple process and low cost, unlike the prior art.

Description

A method for purifying waste lithium phosphate and a method for producing lithium iron phosphate containing the same {METHOD FOR PURIFYING WASTE LITHIUM PHOSPHATE AND METHOD FOR MANUFACTURING LITHIUM IRON PHOSPHATE COMPRISING THE SAME}

The present invention relates to a method for purifying waste lithium phosphate and a method for manufacturing lithium iron phosphate including the same, and more specifically, a high purity of waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery at a simple process and low cost. It relates to a method for purifying waste lithium phosphate that can be purified by using the same and a method for producing lithium iron phosphate including the same.

Lithium batteries are widely used as secondary batteries because of their excellent charge/discharge performance and high energy density, and are particularly widely used in small electronic products such as mobile phones and laptops. Recently, as the spread of electric vehicles has become visible, the development of large-capacity lithium batteries is actively progressing.

Lithium contained in the cathode material of lithium batteries is a very expensive metal and is not produced in Korea, so all of it is imported and used overseas. Therefore, in terms of the characteristics of countries that do not have resources such as Korea, and in terms of preventing environmental pollution due to heavy metals, it is necessary to recover and reuse lithium from waste scraps of cathode materials generated in the lithium battery manufacturing process or cathode materials of lithium batteries that are discarded after use. need.

As a conventional method for extracting or recovering various metals such as lithium from the lithium battery positive electrode material, the positive electrode material removed from the waste lithium battery is extracted with strong acids such as hydrochloric acid, sulfuric acid and nitric acid, and then neutralized with alkali to obtain hydroxides of cobalt and nickel. A process of sedimentation by furnace and recovery of a cathode material with sulfuric acid or nitric acid in the presence of hydrogen peroxide and a process of separating and recovering the metal by neutralization precipitation have been generally used. However, among the known methods of dissolving the anode material, the method of using inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid requires the use of strong acids during the extraction process, so severe environmental pollution due to evaporation into the atmosphere and especially equipment corrosion due to acid The back problem is very serious.

In order to solve the above problem, a method of leaching the positive electrode material using organic acids such as oxalic acid, citric acid, maleic acid, or tartaric acid has been introduced. There is a disadvantage that the recovery rate is low.

In order to improve the leaching efficiency using organic acids, it is necessary to remove the binder and the conductive material contained in the positive electrode material in advance using a heat treatment process, etc., which causes uneconomical disadvantages in terms of time and cost due to the addition of the process. do.

An object of the present invention is to solve the above problems, and to provide a method for purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery with a simple process and low cost with high purity.

According to an aspect of the present invention, there is provided a method for purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery, comprising: (a) preparing a first mixture by mixing the waste lithium phosphate and water; (b) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; And (c) separating the impurities and water from the second mixture to prepare purified lithium phosphate.

The water may include distilled water.

By the heating, step (b) may be performed between 20°C and 70°C.

By the heating, step (b) may be performed between 40°C and 50°C.

Step (b) may be performed for 0.1 to 72 hours.

The purified lithium phosphate may be in a powder form.

Step (c) can be carried out using a vacuum filtration device.

The method for purifying waste lithium phosphate may further include a step (d) of drying the purified lithium phosphate.

^{_{A, SO 4 2-, Co, Ni}} , Mn, Fe, 1 or more kinds selected from the group consisting of Cu, Al and Zn ^- the impurity is ^{Li +, Na +, K +} , Ca 2+, Mg 2+, Cl It may include a compound having.

The impurity may include a compound having at least one selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , Cl ^- and SO ₄ ^2- .

The impurities may include sodium sulfate (Na ₂ SO ₄ ).

According to another aspect of the present invention, in a method for producing lithium iron phosphate (LiFePO ₄ ) using lithium phosphate prepared by purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery, (1) the waste phosphorus Preparing a first mixture by mixing lithium acid and water; (2) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; (3) preparing purified lithium phosphate by separating the impurities and water from the second mixture; And (4) preparing lithium iron phosphate using the purified lithium phosphate. There is provided a method for producing lithium iron phosphate comprising.

The water may include distilled water.

By the heating, step (2) may be performed between 40°C and 50°C.

Step (2) can be carried out for 0.1 to 72 hours.

The method for producing lithium iron phosphate may further include drying the purified lithium phosphate (3').

According to another aspect of the present invention, lithium phosphate prepared by the method for purifying waste lithium phosphate is provided.

The method for purifying waste lithium phosphate and the method for producing lithium iron phosphate of the present invention has an effect of purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery with high purity at a simple process and low cost unlike the prior art. .

In addition, lithium iron phosphate (LiFePO ₄ ) that can be used as a positive electrode material by applying lithium phosphate prepared by the refining method of waste lithium phosphate has an effect of increasing the capacity of the battery.

1 is a flowchart of a method for purifying waste lithium phosphate according to the present invention.
2 is a conceptual diagram of a method for purifying waste lithium phosphate according to the present invention.
3 is an XRD analysis result showing the impurity sodium sulfate (Na ₂ SO ₄ ) of waste lithium phosphate according to Preparation Example 1 and an XRD analysis result of commercial lithium phosphate according to Comparative Example 1. FIG.
FIG. 4A is a litmus test result and pH measurement result of water (distilled water) in step (a) of the waste lithium phosphate purification method, and FIG. 4B is a litmus test result and pH measurement result of water (distilled water) in step (c). .
5A is a TG-DTA analysis result of waste lithium phosphate (Preparation Example 1) before purification, FIG. 5B is a TG-DTA analysis result of lithium phosphate (Example 1) after purification, and FIG. 5C is a waste lithium phosphate (manufacturing DCS analysis results of Example 1 and Example 1).
6 is an SEM analysis result of waste lithium phosphate according to Preparation Example 1 and commercial lithium phosphate according to Comparative Example 1.
7A is a SEM-EDS analysis result of waste lithium phosphate according to Preparation Example 1, and FIG. 7B is an SEM-EDS analysis result of purified lithium phosphate according to Example 1. FIG.
8 is an XRD analysis result of waste lithium phosphate (Preparation Example 1) and purified lithium phosphate (Example 1).
9A is a waste lithium phosphate (Preparation Example 1), FIG. 9B is an ICP and purity analysis result of purified lithium phosphate (Example 1), and FIG. 9C is a waste lithium phosphate (Preparation Example 1) and purified lithium phosphate (Example 1). This is the analysis result of Carbon & Sulfur Determination of the sulfur (S) element in Example 1).
10 is a result of electrochemical characteristics of lithium secondary batteries according to Device Example 1 and Device Comparative Example 2;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention.

However, the following description is not intended to limit the present invention to a specific embodiment, and in describing the present invention, when it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. .

The terms used herein are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, elements, or combinations thereof described in the specification, but one or more other features or It is to be understood that the possibility of the presence or addition of numbers, steps, actions, elements, or combinations thereof is not preliminarily excluded.

1 is a flow chart illustrating a method for purifying waste lithium phosphate according to the present invention, and FIG. 2 is a conceptual diagram illustrating a method for purifying waste lithium phosphate according to the present invention. Hereinafter, a method for purifying waste lithium phosphate according to the present invention will be described in detail with reference to FIGS. 1 and 2.

The present invention provides a method for purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery, comprising: (a) preparing a first mixture by mixing the waste lithium phosphate and water; (b) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; And (c) separating the impurities and water from the second mixture to prepare purified lithium phosphate.

The waste lithium phosphate may be extracted from waste liquid discharged from the recycling process of the waste lithium battery.

The water may include distilled water.

By the heating, the step (b) may be performed between 20° C. and 70° C., and preferably may be performed between 40 and 50° C. In the case of Na ₂ SO _{4, which} is an impurity, the solubility difference varies with temperature. At less than 30℃, the solubility of Na ₂ SO ₄ rapidly decreases, whereas at around 40℃, it shows the highest solubility. Therefore, purification between 40 and 50℃ is most appropriate.

Step (b) may be performed for 0.1 to 72 hours.

The purified lithium phosphate may be in a powder form.

Step (c) can be carried out using a vacuum filtration device.

The method for purifying waste lithium phosphate may further include a step (d) of drying the purified lithium phosphate.

^{_{A, SO 4 2-, Co, Ni}} , Mn, Fe, 1 or more kinds selected from the group consisting of Cu, Al and Zn ^- the impurity is ^{Li +, Na +, K +} , Ca 2+, Mg 2+, Cl May include a compound having, preferably Li ⁺ , Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , Cl ^- and may include a compound having at least one selected from the group consisting of SO ₄ ^2- have.

The impurities may include sodium sulfate (Na ₂ SO ₄ ).

Lithium and lithium compounds, which are the raw materials for the synthesis of cathode materials, which are currently almost dependent on imports, can be extracted from waste batteries by recycling method, and cobalt (Co) and nickel (cobalt (Co)), which are used as cathode materials along with lithium metal and lithium metal compounds, can be used. Ni), manganese (Mn), iron (Fe) metals and related compounds can be recovered from waste resources.

Processed components of the lithium battery waste recycling waste solution is ^{Li +, Na +, K +} , Ca 2+, Mg 2+, Cl -, a ^{_{SO 4 2-, Co, Ni,}} Mn, Fe, Cu, Al, Zn etc. Silver is almost recovered during the recycling of valuable metals and has little effect on purity because its content is less than 1 ppm, but metal ions such as Na, Mg, and Ca and sulfate ions have a sensitive effect on the purity. Should be removed.

In addition, the present invention is a method for producing lithium iron phosphate (LiFePO ₄ ) using lithium phosphate produced by purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery, (1) the waste lithium phosphate and water Mixing to prepare a first mixture; (2) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; (3) preparing purified lithium phosphate by separating the impurities and water from the second mixture; And (4) preparing lithium iron phosphate using the purified lithium phosphate. It provides a method for producing lithium iron phosphate comprising:

The water may include distilled water.

By the heating, step (2) may be performed between 40 and 50°C. In the case of Na ₂ SO _{4, which} is an impurity, the solubility difference varies with temperature. At less than 30℃, the solubility of Na ₂ SO ₄ rapidly decreases, whereas at around 40℃, it shows the highest solubility. Therefore, purification between 40 and 50℃ is most appropriate.

Step (2) can be carried out for 0.1 to 72 hours.

The method for producing lithium iron phosphate may further include drying the purified lithium phosphate (3').

In addition, the present invention provides lithium phosphate prepared by the method for purifying waste lithium phosphate.

In addition, the present invention may provide lithium iron phosphate (LiFePO ₄ ) prepared by a solid phase method using the lithium phosphate, and a positive electrode including the lithium iron phosphate and a battery including the positive electrode may be provided.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes, and the scope of the present invention is not limited thereby.

Preparation Example 1: Waste lithium phosphate extracted from a waste lithium battery (Li ₃ PO ₄ )

Waste lithium phosphate was recovered by a wet treatment method through solvent extraction by a resource recovery process, which is a process of extracting necessary materials from the powder in the recycling step of the waste battery. This is because lithium phosphate is poorly soluble, so it is possible to recover lithium in the form of a lithium phosphate precipitate simply by adding a phosphoric acid supply material in the lithium recovery process.

Example 1: Purification of waste lithium phosphate

The waste lithium phosphate powder (20g) extracted according to Preparation Example 1 is put in distilled water (200ml) at about 50°C, and then heated and stirred for 30 minutes using a magnetic bar to purify. Here, the temperature is maintained at about 40~50℃. Then, the solution and the purified powder are separated using a vacuum filtration device. The vacuum filtration device is a device that can rapidly filter using a vacuum. This is faster than general filtration and is advantageous in removing residual liquid. However, due to the strong suction power due to vacuum, fine crystals may form through the pores of the filter paper, resulting in material that cannot be recovered from the filter paper. After drying the purified powder at 100° C. for about 24 hours, the impurity Na ₂ SO ₄ was finally separated to obtain a purified lithium phosphate powder.

Example 2: Lithium iron phosphate using purified lithium phosphate (LiFePO ₄ ) Of manufacture

Lithium iron phosphate (LiFePO ₄ ) was prepared from the purified lithium phosphate obtained according to Example 1 by a solid phase method.

Device Example 1: Lithium iron phosphate (LiFePO ₄ ) As a positive electrode material

(Manufacture of anode)

Positive electrode active material Lithium iron phosphate (LiFePO ₄ ), conductive material (Super P) and binder (PVDF) prepared according to Example 2 were mixed in a weight ratio of 80:10:10, and the slurry was mixed using a Thinky Mixer for 1 hour. Then, the slurry was applied to a thickness of about 50 μm on an aluminum (Al) foil as a current collector. Then, it was dried in a vacuum oven at 120° C. for 5 hours, and compressed with a roll press to prepare a positive electrode.

(Manufacture of lithium secondary battery)

A lithium secondary battery was manufactured using the positive electrode, lithium metal negative electrode, and 1M LiPF ₆ , EC/DMC 1:1 electrolyte.

Comparative Example 1: Commercial lithium phosphate (Li ₃ PO ₄ )

Commercial lithium phosphate (Li ₃ PO ₄ ) purchased from Sigma Aldrich was used.

Comparative Example 2: Lithium iron phosphate (LiFePO) using waste lithium phosphate before purification ₄ ) Of manufacture

Lithium iron phosphate (LiFePO ₄ ) was prepared by a solid phase method using the waste lithium phosphate powder extracted according to Preparation Example 1.

Device Comparative Example 1: Lithium iron phosphate (LiFePO ₄ ) As a positive electrode material

In Device Example 1, a device was carried out except that lithium iron phosphate (LiFePO ₄ ) prepared according to Comparative Example 2 was used instead of lithium iron phosphate (LiFePO ₄ ) prepared according to Example 2 as the positive electrode active material. A lithium secondary battery was manufactured in the same manner as in Example 1.

[Test Example]

Test Example 1: Lithium phosphate (Li ₃ PO ₄ ) XRD analysis result 1

3 is an XRD analysis result showing the impurity sodium sulfate (Na ₂ SO ₄ ) of waste lithium phosphate according to Preparation Example 1 and an XRD analysis result of commercial lithium phosphate according to Comparative Example 1. FIG.

Referring to FIG. 3, as a result of comparing and analyzing the XRD of commercial lithium phosphate (Comparative Example 1) and waste lithium phosphate (Preparation Example 1), Na ₂ SO ₄ impurities were contained in waste lithium phosphate (Preparation Example 1). I could confirm that.

Test Example 2: Lithium phosphate (Li ₃ PO ₄ ) ICP analysis result

In Table 1 below, the results of component analysis through ICP analysis are described.

Waste lithium phosphate before purification (Preparation Example 1) Lithium phosphate after purification (Example 1) division element content division element content One Li (%) 16.134 One Li (%) 15.50952 2 P (%) 19.608 2 P (%) 18.78476 3 S (%) 2.298 3 S (%) 0.48286 4 Cu (%) 0.068 4 Cu (%) 0 5 Fe (%) 0.024 5 Fe (%) 0 6 As (%) - 6 As (%) - 7 Ca (%) 0.988 7 Ca (%) 0.01238 8 Mg (%) 0.081 8 Mg (%) 0.01333 9 Al (%) 0.164 9 Al (%) 0.00762 10 Co (%) - 10 Co (%) - 11 Ni (%) 0.005 11 Ni (%) 0 12 Na (%) 2.783 12 Na (%) 0.6667 13 Mn (%) 0.001 13 Mn (%) 0 14 Pb (%) - 14 Pb (%) - 15 Zn (%) - 15 Zn (%) - 16 Cd (%) - 16 Cd (%) -

Referring to Table 1, as a result of analyzing the components of lithium phosphate before purification (Preparation Example 1) and lithium phosphate after purification (Example 1), similar to XRD analysis, Na ₂ in lithium phosphate before purification (Preparation Example 1) It was confirmed that the contents of Na and S, which are elements corresponding to the SO ₄ impurity, were very high, and after purification, the ratio of Na and S decreased considerably compared to before purification.

Test Example 3: Litmus test results of distilled water before and after purification

FIG. 4A is a litmus test result and pH measurement result of water (distilled water) in step (a) of the waste lithium phosphate purification method, and FIG. 4B is a litmus test result and pH measurement result of water (distilled water) in step (c). .

4A and 4B, as a result of comparing the pH of the filtered solution after purifying the waste lithium phosphate with distilled water and the distilled water, the color of the litmus test paper remained neutral (pH 7.05) before purification, whereas after purification litmus When the test paper turned to a color representing basicity (pH 10.43), it was indirectly confirmed that Na ₂ SO ₄ and other impurities present in waste lithium phosphate were dissolved.

Test Example 4: TG-DTA and DCS analysis results of waste lithium phosphate before and after purification

5A is a TG-DTA analysis result of waste lithium phosphate (Preparation Example 1) before purification, FIG. 5B is a TG-DTA analysis result of lithium phosphate (Example 1) after purification, and FIG. 5C is a waste lithium phosphate (manufacturing DCS analysis results of Example 1 and Example 1).

5A to 5C, in FIG. 5A, which is a graph before purification, a peak that cannot be seen in FIG. 5B, which is a graph after purification, appeared. In addition, in the DCS graph (FIG. 5C), a peak that did not appear in the graph after refining was confirmed in the graph before refining. This is a peak due to moisture, and it was confirmed that waste lithium phosphate contains moisture before purification. In addition, in the case of purified lithium phosphate, a peak due to moisture was not found because it went through a drying process.

Test Example 5: SEM analysis results of waste lithium phosphate and commercial lithium phosphate

6 is an SEM analysis result of waste lithium phosphate according to Preparation Example 1 and commercial lithium phosphate according to Comparative Example 1.

6, the case of the waste lithium phosphate according to Preparation Example 1 shows a morphology in the form of a rod, and the commercial lithium phosphate shows a shape in which spherical particles having a nanoscale size are aggregated. This is a result of the temperature at the time of manufacture, and according to the reference "Journal of the Korean Journal of Metals and Materials (Korean J. Met. Mater.), Vol. 56, No. 10 (2018) pp.755-762", the reaction temperature during lithium phosphate production It was confirmed that the influence on the size and shape of the lithium phosphate particles.

Test Example 6: SEM-EDS analysis results of waste lithium phosphate and purified lithium phosphate

7A is an SEM-EDS analysis result of waste lithium phosphate according to Preparation Example 1, and FIG. 7B is an SEM-EDS analysis result of purified lithium phosphate according to Example 1. FIG.

7A and 7B, SEM images of Preparation Example 1 and Example 1 both show rod-shaped morphology, and the purified lithium phosphate according to Example 1 was compared to the waste lithium phosphate according to Preparation Example 1 before purification. It was found that the amounts of O and P were relatively large, whereas the amounts of Na and S were relatively decreased. It seems that impurities were reduced by purifying waste lithium phosphate using distilled water.

Test Example 7: Lithium phosphate (Li ₃ PO ₄ ) XRD analysis result 2

8 is an XRD analysis result of waste lithium phosphate (Preparation Example 1) and purified lithium phosphate (Example 1).

Referring to FIG. 8, unlike waste lithium phosphate containing impurities (Preparation Example 1), purified lithium phosphate (Example 1) did not contain impurities, so it was confirmed that the purified lithium phosphate (Example 1) was purified to high purity through the purification method of the present invention.

Test Example 8: Purity analysis results before/after purification of waste lithium phosphate

9A is a waste lithium phosphate (Preparation Example 1), FIG. 9B is an ICP and purity analysis result of purified lithium phosphate (Example 1), and FIG. 9C is a waste lithium phosphate (Preparation Example 1) and purified lithium phosphate (Example 1). This is the analysis result of Carbon & Sulfur Determination of the sulfur (S) element in Example 1). The purity of lithium phosphate (Li ₃ PO ₄ ) was determined by converting from the concentration of Li determined using the order method. And the analysis of each element was determined through ICP analysis. (Li concentration (%) = 18.136-Content of elements detected through ICP analysis (%))

9A to 9C, as a result of confirming the difference in purity between before and after purification, waste lithium phosphate before purification (Li ₃ PO ₄ ) has a very low purity of about 86.116%, while purified lithium phosphate (Li ₃ PO ₄ ) showed a fairly high purity of about 97.122%.

Test Example 9: Evaluation of charge/discharge characteristics of lithium secondary battery

10 is a result of electrochemical characteristics of lithium secondary batteries according to Device Example 1 and Device Comparative Example 2; The charge and discharge conditions of the lithium secondary battery at room temperature (cut-off voltage) 2.5V-4.2V vs. It was set to Li/Li ⁺ , and the charge/discharge rate was 0.1C.

Referring to FIG. 10, initial charge and discharge capacity of a lithium secondary battery including a LiFePO ₄ positive electrode material synthesized by applying waste lithium phosphate (Preparation Example 1) and purified high purity lithium phosphate (Example 1), respectively, was compared. In the case of a battery containing a positive electrode material using waste lithium phosphate (Device Comparative Example 1), the initial discharge capacity was 147.4 mAh/g, and a battery containing a positive electrode material using purified high-purity lithium phosphate (Device Example 1). The case was shown as 160.7mAh/g, and the battery of Device Example 1 showed a relatively high discharge capacity compared to Device Comparative Example 1. This is judged as a decrease in capacity due to impurities in the waste lithium phosphate, as the result of the XRD, ICP analysis and purity analysis, and the impurities are removed through the purification method of the present invention, and purified lithium phosphate (Li ₃ PO ₄ ) is used. This is a result showing that the electrochemical properties of the battery can be improved by applying the synthesized LiFePO ₄ positive electrode material to the battery.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (17)

In the purification method of waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery,
(a) preparing a first mixture by mixing the waste lithium phosphate and water;
(b) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed; And
(c) separating the impurities and water from the second mixture to prepare purified lithium phosphate;
Method for purifying waste lithium phosphate containing. The method of claim 1,
A method for purifying waste lithium phosphate, wherein the water contains distilled water. The method of claim 1,
The method for purifying waste lithium phosphate, characterized in that the step (b) is performed between 20°C and 70°C by the heating. The method of claim 1,
The method for purifying waste lithium phosphate, characterized in that the step (b) is performed between 40°C and 50°C by the heating. The method of claim 1,
A method for purifying waste lithium phosphate, wherein step (b) is performed for 0.1 to 72 hours. The method of claim 1,
A method for purifying waste lithium phosphate, wherein the purified lithium phosphate is in powder form. The method of claim 1,
A method for purifying waste lithium phosphate, characterized in that step (c) is carried out using a vacuum filtration device. The method of claim 1,
The method for purifying the waste lithium phosphate
Drying the purified lithium phosphate (d); Method for purifying waste lithium phosphate, characterized in that it further comprises. The method of claim 1,
^{_{A, SO 4 2-, Co, Ni}} , Mn, Fe, 1 or more kinds selected from the group consisting of Cu, Al and Zn ^- the impurity is ^{Li +, Na +, K +} , Ca 2+, Mg 2+, Cl A method for purifying waste lithium phosphate, comprising a compound having. The method of claim 1,
Purification of waste lithium phosphate, characterized in that the impurity contains a compound having at least one selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , Cl ^- and SO ₄ ^2- Way. The method of claim 1,
The method of purifying waste lithium phosphate, wherein the impurity contains sodium sulfate (Na ₂ SO ₄ ). In the manufacturing method of lithium iron phosphate (LiFePO ₄ ) using lithium phosphate prepared by purifying waste lithium phosphate (Li ₃ PO ₄ ) extracted from a waste lithium battery,
(1) preparing a first mixture by mixing the waste lithium phosphate and water;
(2) heating the first mixture to separate impurities from the waste lithium phosphate to prepare a second mixture in which lithium phosphate and impurities are mixed;
(3) preparing purified lithium phosphate by separating the impurities and water from the second mixture; And
(4) preparing lithium iron phosphate using the purified lithium phosphate;
Method for producing lithium iron phosphate containing. The method of claim 12,
Method for producing lithium iron phosphate, characterized in that the water contains distilled water. The method of claim 12,
Method for producing lithium iron phosphate, characterized in that the step (2) is performed between 40 and 50°C by the heating. The method of claim 12,
A method for producing lithium iron phosphate, characterized in that step (2) is carried out for 0.1 to 72 hours. The method of claim 12,
The method for producing lithium iron phosphate
Drying the purified lithium phosphate (3'); the method for producing lithium iron phosphate, characterized in that it further comprises. Lithium phosphate produced by the method for purifying waste lithium phosphate according to claim 1.

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