JP2018041683A - Method for manufacturing olivine type lithium phosphate-based positive electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an olivine type lithium phosphate-based positive electrode material, in which a particular raw material including a lithium compound is subjected to a solid-liquid separation step after gone through a hydrothermal reaction, which enables the reuse of sump solution, and which enables the effective reduction in a S source which is an impurity even if a metal sulfate is used as a metal source of the raw material.SOLUTION: A method for manufacturing an olivine type lithium phosphate-based positive electrode material represented by a particular formula comprises the steps of: (II) dropping an alkali solution into a mixture solution obtained in the step (I) to obtain LiPOparticles; (III) rinsing LiPOparticles obtained in the step (II), subsequently, adding a metal sulfate or its hydrate thereto and mixing them together to obtain a slurry liquid, and causing a hydrothermal reaction thereof to obtain a reaction mixture; and (IV) separating a solution including unreacted Li ions from the reaction mixture obtained in the step (III) to obtain the olivine type lithium phosphate-based positive electrode material. In the step (I), a solution including unreacted Li ions separated in the step (IV) is used as all or part of a solution in which a lithium compound is completely dissolved. In the step (III), a mole ratio of POions to SOions in the slurry liquid, and a mole ratio (alkali:SO) of alkali to SOions are particular values.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an olivine-type lithium phosphate-based positive electrode material capable of recovering unreacted Li and effectively reusing it.

  Lithium ion secondary batteries have established themselves as high-capacity and lightweight power supplies that are indispensable for portable electronic terminals and electric vehicles. With the recent increase in power consumption due to higher performance of electronic devices, further increase in capacity of lithium ion secondary batteries is required. In order to improve the performance of such a battery, various positive electrode materials using lithium manganese phosphate, lithium iron phosphate, or the like having an olivine structure obtained by a process subjected to a hydrothermal reaction have been developed.

By the way, in hydrothermal synthesis of a lithium phosphate-based positive electrode material having an olivine type structure, a large amount of Li ions remaining in the liquid phase after hydrothermal synthesis is discarded. This excessively consumes the most expensive Li source among the raw materials, which increases the manufacturing cost of the olivine type lithium phosphate positive electrode material. In response to this problem, attempts have been made to recover and reuse Li ions in the liquid phase after hydrothermal synthesis based on various methods. For example, Non-Patent Document 1 discloses a liquid phase after hydrothermal synthesis. A method for recovering Li ₂ CO ₃ by adding Na ₂ CO ₃ after adjusting the pH has been proposed.

In Patent Document 1, Li ions in a liquid phase after hydrothermal synthesis are recovered as Li ₃ PO ₄ which is hardly soluble in water and can be used as a precursor of an olivine-type lithium phosphate positive electrode material. A method has been proposed. This method includes a first step of mixing a metal source and a reducing agent in a lithium phosphate slurry, a second step of hydrothermal reaction of the obtained mixture, and the obtained reaction product as an olivine type lithium phosphate system. A third step of separating the positive electrode material and a solution containing unreacted Li, and a fourth step of reacting the purified solution containing unreacted Li with phosphoric acid to form a lithium phosphate slurry. By using the lithium phosphate slurry obtained in the fourth step in the first step, unreacted Li is recovered and reused.

Under these circumstances, when sulfate is used as a metal source as a raw material, a certain amount of sulfate-derived SO ₄ ²⁻ may remain as impurities in the obtained positive electrode active material, which becomes the S source. Volatile gas is generated, which can also cause expansion in the resulting lithium ion battery. Therefore, it is strongly desired to remove the S source as much as possible.

JP 2008-66019 A

"Chemical products of 13599", published by Chemical Industry Daily, 1999, p. 191

However, in the method described in Non-Patent Document 1, since Li ₂ CO ₃ has a relatively high solubility in water, it is difficult to efficiently recover Li ions in the liquid phase. Further, even in the method described in Patent Document 1, since the liquid phase has a high pH by adding a solid phase Li source to the liquid phase after hydrothermal synthesis in the fourth step, A part of the Li source remains undissolved, and if sulfate is used as the metal source, the S source may not be sufficiently reduced.

  Accordingly, an object of the present invention is to reuse the drainage in a method for producing an olivine-type lithium phosphate positive electrode material that undergoes a solid-liquid separation process after subjecting a specific raw material containing a lithium compound or the like to a hydrothermal reaction. An object of the present invention is to provide a method for producing a lithium phosphate-based positive electrode active material that can effectively reduce the S source as an impurity even when a metal sulfate salt is used as a raw metal source.

Therefore, the present inventors have made various studies, through a so-called liquid-liquid reaction using a solution in which a lithium compound or the like is completely dissolved, and then through a specific hydrothermal reaction step and a solid-liquid separation step, Specific components while reusing the liquid-liquid reaction waste liquid in the liquid mixture after hydrothermal synthesis and the liquid phase of the stoichiometric component complementation to generate Li ₃ PO ₄ Of the olivine type lithium phosphate cathode material capable of effectively reducing the remaining S source while using a metal sulfate salt as a raw material metal source by controlling the molar ratio of The method has been found and the present invention has been completed.

That is, the present invention relates to LiFe _a Mn _b M _c PO ₄ (where M represents Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a , B and c are numbers satisfying 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.3, and 2a + 2b + (valence of M) × c = 2 and satisfying a + b ≠ 0. Olivine type lithium phosphate positive electrode material represented by
Step (I) of mixing a solution in which a lithium compound is completely dissolved and a solution in which a lithium compound and a phosphate compound are completely dissolved to obtain a mixed solution;
A step (II) in which an alkaline solution is dropped into the mixed solution obtained in the step (I) to obtain Li ₃ PO ₄ particles;
The Li ₃ PO ₄ particles obtained in step (II) are washed, and then a metal sulfate or a hydrate thereof is added and mixed to obtain a slurry liquid, which is then subjected to a hydrothermal reaction to obtain a reaction mixture. Step (III),
Separating the solution containing unreacted Li ions from the reaction mixture obtained in step (III) to obtain an olivine-type lithium phosphate-based positive electrode material (IV),
In step (I), the solution containing unreacted Li ions separated in step (IV) is used as all or part of the solution in which the lithium compound is completely dissolved. In step (III), the PO in the slurry liquid is used. The molar ratio of ₄ ions to SO ₄ ions (PO ₄ : SO ₄ ) is 1.05: 1 to 2: 1, and the molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) is 2.1: The present invention provides a method for producing an olivine-type lithium phosphate positive electrode material having a ratio of 1 to 4: 1.

  According to the production method of the present invention, since a liquid-liquid reaction using a solution in which a lithium compound and a phosphate compound are completely dissolved and a solution in which a lithium compound is completely dissolved is performed, a desired raw material that once contains a lithium compound or the like is added. An olivine-type lithium phosphate positive electrode material that is obtained after being subjected to a hydrothermal reaction and effectively reduces the amount of S source that can remain while effectively reusing wastewater that has been only a target for disposal. Can be manufactured. Therefore, it is possible to easily realize a high-performance lithium ion battery with high safety while using lithium, which is a rare material, without waste.

Hereinafter, the present invention will be described in detail.
The method for producing the olivine-type lithium phosphate positive electrode material of the present invention includes:
LiFe _a Mn _b M _c PO ₄ (M represents Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a, b, and c are 0. ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.3, and 2a + 2b + (the valence of M) × c = 2 and a number satisfying a + b ≠ 0. Type lithium phosphate positive electrode material manufacturing method,
Step (I) of mixing a solution in which a lithium compound is completely dissolved and a solution in which a lithium compound and a phosphate compound are completely dissolved to obtain a mixed solution;
A step (II) in which an alkaline solution is dropped into the mixed solution obtained in the step (I) to obtain Li ₃ PO ₄ particles;
The Li ₃ PO ₄ particles obtained in step (II) are washed, and then a metal sulfate or a hydrate thereof is added and mixed to obtain a slurry liquid, which is then subjected to a hydrothermal reaction to obtain a reaction mixture. Step (III),
Separating the solution containing unreacted Li ions from the reaction mixture obtained in step (III) to obtain an olivine-type lithium phosphate-based positive electrode material (IV),
In step (I), the solution containing unreacted Li ions separated in step (IV) is used as all or part of the solution in which the lithium compound is completely dissolved. In step (III), the PO in the slurry liquid is used. The molar ratio of ₄ ions to SO ₄ ions (PO ₄ : SO ₄ ) is 1.05: 1 to 2: 1, and the molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) is 2.1: 1 to 4: 1.

Examples of the lithium compound used in the step (I) included in the present invention include lithium hydroxide (for example, LiOH.H ₂ O), lithium carbonate (for example, Li ₂ CO ₃ ), lithium sulfate, lithium acetate, and hydrates thereof. Is mentioned. Of these, lithium carbonate is preferable from the viewpoint of reducing manufacturing costs.
From the viewpoint of facilitating dissolution in water, the maximum particle size of the lithium compound is preferably 5 mm or less, and more preferably 1 mm or less.

Examples of the phosphoric acid compound used in the step (I) include orthophosphoric acid (H ₃ PO ₄ , phosphoric acid), metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, ammonium phosphate, and ammonium hydrogen phosphate. . Of these, phosphoric acid is preferably used, and is preferably used as an aqueous solution having a concentration of 70 to 90% by mass.

  In step (I), a solution in which the lithium compound is completely dissolved (hereinafter also referred to as “solution A1”) and a solution in which the lithium compound and the phosphate compound are completely dissolved (hereinafter also referred to as “solution A2”) are obtained. It is preferable to mix these compounds with water. Specifically, water is mixed with the lithium compound, and the solution A1, which is an aqueous solution in which the lithium compound is completely dissolved in water, is mixed with water with the lithium compound and the phosphoric acid compound. It is preferable to use Solution A2, which is a completely dissolved aqueous solution. A solution in which a lithium compound or a lithium compound and a phosphoric acid compound are completely dissolved is a solute lithium compound, or a lithium compound and a phosphoric acid compound that are completely dissolved in a solvent, resulting in suspensions and precipitates in the solution. In other words, it means a highly transparent solution, which is a liquid material different from a so-called slurry.

The solution A1 preferably contains 1.8 to 2.2 mol of lithium and more preferably 1.9 to 2.1 mol with respect to 1 mol of phosphorus in the other solution A2. In order to be such an amount, that is, in the step (III) described later, the molar ratio (PO ₄ : SO ₄ ) of PO ₄ ions to SO ₄ ions in the slurry liquid is maintained at a predetermined value. Any of the above lithium compounds may be used. For example, the content of the lithium compound in the solution A1 is preferably 0.1 to 33 g / L, more preferably 1 to 33 g / L.

Here, the lithium content (g) required for the solution A1 is the same level as the lithium content (g) in the liquid phase in the reaction mixture obtained by hydrothermal reaction in the step (III) described later. Therefore, the solution containing unreacted Li ions obtained in the solid-liquid separation step in the subsequent step (IV) (hereinafter also referred to as “drainage obtained in step (IV)”) is added to all of the solution A1 or Used as part. As a result, it is possible to effectively reuse the waste liquid that is obtained after subjecting a desired raw material containing a lithium compound or the like to a hydrothermal reaction and is only a target of disposal. When using the effluent obtained in step (IV), as described later, in order to determine the amount of alkali added, the concentration (mg / L) of impurities such as SO ₄ ions in the effluent is measured. Is preferred. For this measurement, a general analysis method such as an ICP emission spectroscopic analysis method, an ion chromatography analysis method, or an ion electrode method can be used. Of these, the ion electrode method is preferably used from the viewpoint of simplicity.

  The other solution A2 corresponds to the lithium concentration of the solution A1 to be mixed so that the mixed solution obtained by mixing the solution A1 and the solution A2 contains 2.9 to 3.1 mol of lithium with respect to 1 mol of phosphorus. What is necessary is just to use the said lithium compound and phosphoric acid compound so that it may become content. For example, the total content of the lithium compound and the phosphate compound in the solution A2 is preferably 10 to 1500 g / L, more preferably 100 to 1500 g / L.

  Since the preparation of the solution A2 used in the step (I) depends on the value of the lithium concentration (g / L) of the solution A1, the ICP emission spectroscopic analysis method, the ion chromatography analysis method, etc. What is necessary is just to use the design density | concentration of the solution A1 which measured the lithium density | concentration by utilizing a general analysis method.

  In the preparation of the solution A2, it is preferable to add and mix the phosphoric acid compound to the preliminary solution containing the lithium compound from the viewpoint of ensuring the uniformity of the resulting mixed solution. Before adding the phosphoric acid compound, it is preferable to stir the preliminary solution containing the lithium compound in advance. The stirring time of the preliminary solution containing the lithium compound used for the preparation of the solution A2 is preferably 1 to 20 minutes, more preferably 5 to 15 minutes. Moreover, the temperature of the preliminary solution containing the lithium compound used for the preparation of the solution A2 is preferably 20 to 90 ° C, more preferably 20 to 70 ° C. By this stirring, a solution A2 in which both the lithium compound and the phosphate compound are completely dissolved is obtained.

  In addition, when adding and mixing a phosphoric acid compound to a preliminary solution containing such a lithium compound, it is preferable to use phosphoric acid as the phosphoric acid compound and add the phosphoric acid dropwise while stirring the preliminary solution. By adding dropwise phosphoric acid dropwise to the preliminary solution, mixing proceeds well in the resulting solution A2, and the uniformity of the solution A2 can be ensured. The dropping rate of phosphoric acid into the preliminary solution containing the lithium compound is preferably 10 to 100 mL / min, more preferably 20 to 80 mL / min, and further preferably 30 to 70 mL / min. Moreover, the stirring time of the preliminary solution while dropping phosphoric acid is preferably 1 to 15 minutes, more preferably 3 to 10 minutes.

In mixing the solution A1 and the solution A2, the solution A1 is preferably mixed with the solution A2, and the solution A2 is preferably mixed while stirring. Thereby, the uniformity of mixing of the obtained mixed solution is securable. Thus, the molar ratio of Li to PO ₄ contained in the mixed solution obtained in step (I) is preferably 2.8: 1 to 3.2: 1, more preferably 2.9: 1 to 3: 1. .1: 1.

Step (II) included in the present invention is a step of obtaining Li ₃ PO ₄ particles by dropping an alkaline solution into the mixed solution obtained in Step (I). Specifically, it is preferable that the alkaline solution is dropped into the mixed solution obtained in the step (I), and then stirred to precipitate and collect Li ₃ PO ₄ particles. The dropping of the alkaline solution makes it easy to adjust the addition rate, neutralizes the acidic mixed solution, and the Li ion and PO ₄ ion in the mixed solution are hardly soluble and controlled to an appropriate particle size. In order to promote the formation of the formed Li ₃ PO ₄ particles. Further, as the whole or a part of the solution A1 used in the step (I), while using the effluent obtained in the step (III) described later, the Li ₃ PO ₄ particles due to impurities such as SO ₄ ions in the effluent are used. It is possible to effectively reduce the residual amount of S while preventing a decrease in purity. In the present invention, the alkaline solution dripped here is more specific mol with respect to SO ₄ ions having a specific molar ratio described later with PO ₄ ions in the slurry liquid in step (III) described later. Drop in such an amount as to have a ratio. That is, by dripping an alkaline solution so as to have such a specific quantitative relationship, hardly soluble Li ₃ PO ₄ particles are formed, and impurities such as SO ₄ ions brought from the drainage are easily dissolved in water. Since it becomes a soluble product, it is possible to efficiently produce Li ₃ PO ₄ particles having a high purity, a preferable particle size, and an effective reduction of the S source.

The stirring time of the mixed solution is preferably 1 to 24 hours, and more preferably 6 to 18 hours. Moreover, the temperature of a mixed solution becomes like this. Preferably it is 5-90 degreeC, More preferably, it is 20-70 degreeC. In addition, the dropping rate of the alkaline solution for obtaining Li ₃ PO ₄ particles having a preferable particle size and effectively reduced S source is 0.6 mol / L Li and PO _{4 in} terms of Li ₃ PO _4. The amount is preferably 0.05 to 1.0 mol / min, more preferably 0.25 to 0.70 mol / min per 1 L of the dissolved mixed solution.

As the alkali used in the alkaline solution, ammonia, aqueous ammonia, or hydroxide such as sodium hydroxide is preferable. Among these, sodium hydroxide is used from the viewpoint of improving the battery characteristics of the positive electrode active material made of the olivine-type lithium phosphate positive electrode material produced from the recovered Li ₃ PO ₄ particles and the recovery rate of Li ₃ PO ₄ particles. Is preferred. As such sodium hydroxide, either solid (granular or flaky) or aqueous solution may be used as an alkaline solution, and an alkaline aqueous solution is preferable.
From the viewpoint of promoting the formation of Li ₃ PO ₄ particles, the total dropwise addition amount of the alkaline solution is preferably such that the pH of the mixed solution obtained in step (I) is 5 to 13, more preferably 6 to 13. preferable. In addition, while using the drainage obtained in the step (III) described later, from the viewpoint of making impurities such as SO ₄ ions in the drainage easily soluble in water, the molar amount of alkali in the alkali solution, The amount is preferably 2 to 4 times, more preferably 2 to 3 times the molar amount of SO ₄ ions, etc. in the effluent used.

In order to precipitate and recover Li ₃ PO ₄ particles from the mixed solution, it is preferable to perform solid-liquid separation of the solution. As an apparatus used for solid-liquid separation, a filter press machine, a centrifugal filter, a vacuum filter, etc. are mentioned, for example. Among them, from the viewpoint of obtaining efficiently Li ₃ PO ₄ particles, it is preferable to use a filter press.

The Li ₃ PO ₄ particles obtained in the step (II) are products obtained through a so-called liquid-liquid reaction using the mixed solution obtained in the step (I). Small. Here, the maximum particle size of the Li ₃ PO ₄ particles (secondary particles) is preferably 20 μm or less, and more preferably 10 μm or less. By setting the maximum particle size of the Li ₃ PO ₄ particles to 20 μm or less, the obtained Li ₃ PO ₄ particles can be used for the subsequent step without being pulverized. On the other hand, if the Li ₃ PO ₄ particles are too small, the particle size of the olivine-type lithium phosphate positive electrode material obtained thereafter tends to be too small, and the amount of adsorbed moisture of the positive electrode active material tends to increase. This causes a decrease in battery characteristics, particularly rate characteristics. Therefore, there is a lower limit to the preferable particle size of the Li ₃ PO ₄ particles, and the particle size is preferably 100 nm or more, and more preferably 250 nm or more. The average particle diameter of the Li ₃ PO ₄ particles is preferably 1 to 10 [mu] m, more preferably 1 to 6 m.

Furthermore, Li ₃ PO ₄ particles obtained in the step (II), while using the waste liquid obtained in later-described step (III), S source is being effectively reduced, specifically, Li ₃ PO ₄ The S content in the particles is preferably 0.3% by mass or less, more preferably 0.25% by mass or less. Moreover, the BET specific surface area of such Li ₃ PO ₄ particles is preferably 20 to 150 m ² / g, more preferably 30 to 80 m ² / g. Furthermore, S of Li ₃ PO ₄ particles to a BET specific surface area per Li ₃ PO ₄ particles 1g, preferably ^{1 × 10 -6 ~6 × 10 -5} g / m 2, more preferably 1 It is * 10 < ^-6 > ^-5 * 10 < ^-5 > g / m < ² >.

In the step (III) provided by the present invention, the Li ₃ PO ₄ particles obtained in the step (II) are washed, and then a metal sulfate or a hydrate thereof is added and mixed to obtain a slurry A, This is a step of obtaining a reaction mixture by subjecting to a hydrothermal reaction. Water is preferably used for cleaning the Li ₃ PO ₄ particles. Specifically, it is preferable to use 5 to 100 parts by mass of water and more preferably 10 to 90 parts by mass with respect to 1 part by mass of Li ₃ PO ₄ particles. As described above, the waste liquid obtained in the step (III) is used as all or part of the solution A in which the lithium compound is completely dissolved in the step (I) by washing with an excessive amount of water. However, since the S source is effectively reduced, an olivine type lithium phosphate positive electrode material that exhibits excellent battery physical properties can be obtained.

The water content of the washed Li ₃ PO ₄ particles (cake) is preferably measured and used to determine the amount of water added to the mixture for hydrothermal reaction. The water content can be easily measured with an infrared moisture meter or the like. The washed Li ₃ PO ₄ particles (cake) are more preferably dried. By drying, the amount of water in the mixture subjected to the hydrothermal reaction can be managed with high accuracy. As a means for drying the Li ₃ PO ₄ particles, freeze drying or vacuum drying is preferable.

  Examples of the metal sulfate salt or hydrate thereof which is a metal source used in the step (III) include a metal sulfate salt containing an iron compound and / or a manganese compound or a hydrate thereof. Examples of the sulfate metal salt containing iron compound or hydrate thereof include divalent iron compounds and hydrate thereof, such as iron sulfate or hydrate thereof, and sulfate metal salt containing manganese compound or hydrate thereof. Examples of the product also include divalent manganese compounds and manganese hydrates or hydrates thereof.

  As a metal compound other than the iron compound and the manganese compound, M in the formula (A) described later as a metal (M is Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd.) Sulfates containing these or hydrates thereof. Especially, it is preferable to use the metal (M) sulfate whose M is Mg or Zr from a viewpoint of improving a battery physical property.

  When using both a sulfate metal salt containing an iron compound or a hydrate thereof and a sulfate metal salt containing a manganese compound or a hydrate thereof as the metal sulfate salt or hydrate thereof, the molar ratio used (manganese compound: The iron compound) is preferably 99: 1 to 51:49, more preferably 95: 5 to 55:45, and still more preferably 90:10 to 60:40.

By adding and mixing the above-described iron compound and / or manganese compound sulfate or its hydrate to a Li ₃ PO ₄ -containing mixture composed of Li ₃ PO ₄ particles washed with water and water, A slurry liquid A for subjecting to a thermal reaction is produced. The order of adding such metal sulfate salts or hydrates thereof is not particularly limited. In the present invention, the metal sulfate salt or hydrate added here has a molar ratio of PO ₄ ions to SO ₄ ions (PO ₄ : SO ₄ ) of 1.05: 1 in the resulting slurry A solution. The molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) is 2.1: 1 to 4: 1. That is, by adding a metal sulfate salt or a hydrate thereof so as to achieve such a specific quantitative relationship in the slurry A solution, not only Li ₃ PO ₄ particles but also olivine-type lithium phosphate obtained therefrom Even in the positive electrode material, the S source can be effectively reduced.

The molar ratio (PO ₄ : SO ₄ ) of PO ₄ ions to SO ₄ ions in the slurry A liquid is preferably 1.1: 1 to 1.8: 1, more preferably 1.2: 1 to 1. 1.6: 1. The molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) is preferably 2.2: 1 to 3: 1, more preferably 2.6: 1 to 3: 1.

Li ₃ PO ₄ containing mixture before mixing the metal sulfate or a hydrate thereof to preferably allowed to stir in advance according Li ₃ PO ₄ containing mixture. The stirring time of the Li ₃ PO ₄ -containing mixture is preferably 1 to 10 minutes, more preferably 2 to 8 minutes. By this stirring, a Li ₃ PO ₄ containing mixture in which uniformity is ensured can be obtained.

Then, in obtaining a Li ₃ PO ₄ containing mixture in slurry A was added and mixed metal sulfate or a hydrate thereof, performs addition and mixing with stirring Li ₃ PO ₄ containing mixture. The pH of the slurry liquid A is preferably 3.5 to 8, more preferably 4 to 7. The total amount of these metal sulfate salts or hydrates added is preferably 0.98 to 1.02 moles, more preferably 0, with respect to 1 mole of Li ₃ PO ₄ contained in the slurry liquid A. .99 to 1.01 mol.

The obtained slurry liquid A containing Li ₃ PO ₄ and a sulfate metal salt or a hydrate thereof is subjected to a hydrothermal reaction. Thereby, the compound used as an olivine type lithium phosphate positive electrode material is produced | generated, and the reaction mixture containing this can be obtained. The amount of water used in producing the slurry liquid A is contained in the slurry liquid A from the viewpoints of the solubility of the metal sulfate salt or its hydrate, the ease of stirring, the efficiency of synthesis, and the like. to ₃ PO ₄ 1 mol, preferably 10 to 30 moles, more preferably 12.5 to 25 mol.
Moreover, you may add antioxidant to the slurry liquid A attached | subjected to the said hydrothermal reaction as needed. As such an antioxidant, sodium sulfite (Na ₂ SO ₃ ), hydrosulfite sodium (Na ₂ S ₂ O ₄ ), aqueous ammonia and the like can be used. The addition amount of the antioxidant is 1 mol of a metal sulfate salt or a hydrate thereof from the viewpoint of preventing generation of a compound that becomes an olivine type lithium phosphate positive electrode material by being added in excess. On the other hand, it is preferably 0.01 to 1 mol, more preferably 0.03 to 0.5 mol.

  Hydrothermal reaction should just be 100 degreeC or more, and 130-180 degreeC is preferable. Such a hydrothermal reaction is preferably performed in a pressure vessel. When the reaction is performed at 130 to 180 ° C., the pressure at this time is preferably 0.3 to 0.9 MPa, and the reaction is performed at 140 to 160 ° C. The pressure in this case is preferably 0.3 to 0.6 MPa. The hydrothermal reaction time is preferably 0.5 to 24 hours, more preferably 3 to 12 hours.

In the step (IV) provided by the present invention, the solution containing unreacted Li ions is separated from the reaction mixture containing the olivine type lithium phosphate positive electrode material obtained in the step (III), and the olivine type lithium phosphate type This is a step of obtaining a positive electrode material. An apparatus used for so-called solid-liquid separation for separating a solution containing unreacted Li ions from the reaction mixture can be the same as in the above step (II), and a viewpoint of efficiently obtaining a positive electrode material. Therefore, it is preferable to use a filter press.
Further, the obtained positive electrode material is preferably washed with water. When the positive electrode material is washed with water, it is preferable to use 5 to 20 parts by mass of water and more preferably 10 to 15 parts by mass with respect to 1 part by mass of the positive electrode material.
Since the washed water contains unreacted Li ions washed away from the positive electrode material, the present invention collects the whole amount of the washed water, and together with the solution obtained by solid-liquid separation, the solution A1 in the step (I). Used as all or part of In order to efficiently collect the washing water, it is preferable to perform washing and solid-liquid separation using a filter press machine. The obtained recovered water does not need to be contaminated by impurities before it is used in step (I), and does not require a special storage environment. Moreover, in order to adjust the Li ion concentration in the recovered water, a dilution operation or a concentration operation can be performed by a general method.

  The olivine-type lithium phosphate positive electrode material separated and recovered in step (IV) is dried as necessary. Examples of the drying means include spray drying, vacuum drying, freeze drying and the like.

The olivine type lithium phosphate positive electrode material obtained by the production method of the present invention has the following formula (A):
LiFe _a Mn _b M _c PO ₄ (A)
(In formula (A), M represents Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd. A, b, and c are 0 ≦ a ≦. 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.3, and 2a + 2b + (M valence) × c = 2 and a number satisfying a + b ≠ 0 are shown.)
It is represented by

The olivine-type lithium phosphate positive electrode material represented by the above formula (A) contains at least manganese (Mn) or iron (Fe). That is, in the formula (A), M represents Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, preferably Mg or Zr. a is 0 ≦ a ≦ 1, preferably 0 <a <0.5, and more preferably 0.1 <a <0.3. b is 0 ≦ b ≦ 1, preferably 0.5 <b <1, and more preferably 0.7 <b <0.9. These a and b are not 0 at the same time. c satisfies 0 ≦ c ≦ 0.3, and preferably 0.05 ≦ c ≦ 0.25. These a, b and c are numbers satisfying 2a + 2b + (valence of M) × c = 2 and satisfying a + b ≠ 0. Specific examples of the olivine-type lithium phosphate positive electrode material represented by the above formula (A) include LiFePO ₄ , LiMnPO ₄ , LiFe _0.2 Mn _0.8 PO ₄ , LiFe _0.1 Mn _0.8 Mg _0.1 PO ₄ , and LiFe _0.1. Mn _0.8 Zr _0.05 PO ₄ and the like.

The obtained olivine-type lithium phosphate positive electrode material is preferably made into a positive electrode active material by carrying carbon and then firing it. For carbon loading, carbon source such as glucose, fructose, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, saccharose, starch, dextrin, citric acid and water are added to olivine type lithium phosphate positive electrode material in a conventional manner, and then calcined. do it. The firing conditions are 400 ° C. or higher, preferably 400 to 800 ° C. for 10 minutes to 3 hours, preferably 0.5 to 1.5 hours under an inert gas atmosphere or reducing conditions. By such treatment, a positive electrode active material in which carbon is supported on the particle surface of the positive electrode material can be obtained. The amount of the carbon source to be used is preferably 3 to 15 parts by mass as carbon contained in the carbon source and more preferably 5 to 10 parts by mass as carbon contained in the carbon source with respect to 100 parts by mass of the positive electrode material.

  In addition to the above treatment, as a treatment for supporting carbon on the surface of the particles, for example, a method of pulverizing / compositing / mixing a mixture containing the obtained olivine type lithium phosphate positive electrode material and a conductive carbon material. May be used. By performing such treatment, a positive electrode active material in which the positive electrode material and the conductive carbon material are combined can be formed, and the conductivity can be further increased.

  The conductive carbon material used in the pulverization / combination / mixing treatment is preferably carbon black, and more preferably acetylene black or ketjen black. The addition amount of the conductive carbon material is preferably 0.5 to 15 parts by mass in terms of carbon atom with respect to 100 parts by mass of the positive electrode material from the viewpoint of good discharge capacity and economy, and 2 to 10 parts by mass. More preferably, it is part.

  The mixture of the olivine type lithium phosphate positive electrode material and the conductive carbon material is pulverized / composited / mixed in a dry manner. At this time, a small amount of diethylene glycol, ethanol or the like may be added as an auxiliary agent.

  As an apparatus for pulverizing / combining / mixing, a normal ball mill may be used, but a planetary ball mill (manufactured by Fritsch) capable of rotating and revolving is preferred, and nobilta (manufactured by Hosokawa Micron), multipurpose mixer (manufactured by Nippon Coke Kogyo Co., Ltd.). ), Or a hybridizer (manufactured by Nara Machinery Co., Ltd.), etc., as long as it can perform a mechanochemical action / combination treatment on the workpiece.

Examples of the container of the device used in the planetary ball mill include steel, stainless steel, and nylon, and the inner wall includes alumina brick, magnetic material, natural silica, rubber, urethane, and the like. As the ball, alumina sphere, natural silica, iron ball, zirconia ball or the like is used. The size of the ball is preferably 0.1 mm to 20 mm, more preferably 0.5 mm to 5 mm. The filling amount of the balls is preferably set to a ratio that the filling volume of the balls occupies 5 to 50% with respect to the internal volume of the mill to be used.
Mixing using a planetary ball mill is performed, for example, under conditions of revolution of 50 to 800 rpm and rotation of 100 to 1,600 rpm, preferably 5 minutes to 24 hours, more preferably 0.5 to 6 hours, and further preferably 1 to 3 hours.

The positive electrode active material in which carbon is combined on the surface of the olivine type lithium phosphate positive electrode material as described above is preferably at 500 to 800 ° C. for 10 minutes to 24 hours under an inert gas atmosphere or under reducing conditions. Preferably, baking is performed at 600 to 700 ° C. for 0.5 to 3 hours. By this treatment, a positive electrode active material in which carbon is further firmly supported on the surface of the positive electrode material can be obtained. The apparatus used for firing is not particularly limited as long as the firing atmosphere and temperature can be adjusted, and any of a batch system, a continuous system, and a heating system (indirect or direct) can be used. . Examples of such an apparatus include tubular electric furnaces such as an external heat kiln and a roller hearth.

The positive electrode active material obtained by the above method effectively reduces the S source in the positive electrode active material, coupled with the use of Li ₃ PO ₄ particles in which the S content is effectively reduced while recycling the drainage. Is done. Specifically, the S content of the positive electrode active material obtained by the method for producing an olivine type lithium phosphate positive electrode material of the present invention is preferably 0.7% by mass or less, more preferably 0.6% by mass. It is as follows. Moreover, it may be controlled to a moderately fine particle diameter, and the crystallite diameter of the positive electrode active material is preferably 10 to 80 nm, and more preferably 30 to 60 nm.

Next, a lithium ion secondary battery containing the olivine type lithium phosphate positive electrode active material obtained by the method of the present invention as a positive electrode constituent material will be described.
The lithium ion secondary battery to which the positive electrode constituent material of the present invention can be applied is not particularly limited as long as it has a positive electrode, a negative electrode, an electrolytic solution, and a separator as essential components.

  Here, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material structure is not particularly limited, and a known material structure can be used. For example, a carbon material such as lithium metal, graphite, or amorphous carbon. It is preferable to use an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium, particularly a carbon material.

  The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used for an electrolyte solution of a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones An oxolane compound or the like can be used.

The type of the supporting salt is not particularly limited, but an inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , a derivative of the inorganic salt, LiSO ₃ CF ₃ , LiC (SO ₃ CF ₃ ) ₂ and LiN (SO ₃ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), and organic salt derivatives It is preferable that it is at least 1 type of these.

  The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Example 1]
<Manufacture of lithium-containing drainage>
A preliminary solution was obtained by mixing 11.195 g of Li ₂ CO ₃ and 30 mL of water. Next, while maintaining the obtained preliminary solution at a temperature of 20 ° C. for 5 minutes while stirring, 13.67 g of a 75% aqueous phosphoric acid solution was added dropwise at 35 mL / min, followed by stirring at a temperature of 20 ° C. for 12 hours. Solution A containing Li ₃ PO ₄ was obtained.

Next, 19.286 g of MnSO ₄ .5H ₂ O and 5.560 g of FeSO ₄ .7H ₂ O are added to the total amount of the solution A containing Li ₃ PO ₄ to obtain a mixed solution having a pH of 4.5. It was. At this time, the molar ratio of MnSO ₄ and FeSO ₄ added (manganese compound: iron compound) was 80:20.

Subsequently, the obtained liquid mixture was thrown into the autoclave and hydrothermal reaction was performed at 170 degreeC for 0.5 hour. The pressure in the autoclave was 0.8 MPa. The produced suspension was allowed to cool naturally, and then filtered through a filter press device to obtain a liquid component (lithium-containing effluent A).
Additionally, solids (manganese phosphate lithium iron compound _{(LiMn 0.8 Fe 0.2 PO 4)} ) with respect to 1 part by weight, and washed with 12 parts of water.
For a solution (solution A1) obtained by mixing lithium-containing effluent A recovered from hydrothermal synthesis with the cleaning water recovered from the above washing step, the Li concentration measured by ICP emission spectrometry was 1000 mg / L, and the S concentration was It was 67700 mg / L.

<< Manufacture of cathode material >>
Li ₂ CO _{3 (} 2.620 g) and water (10 mL) were mixed to obtain a preliminary solution. Next, 10.0903 g of 75% aqueous phosphoric acid solution was added dropwise at 35 mL / min while stirring the obtained preliminary solution at a temperature of 20 ° C. for 3 minutes. Thereafter, the mixture was stirred until Li ₂ CO ₃ was completely dissolved and the solution became transparent to obtain a solution A2.
After 100 g of the solution A1 was added to the solution A2 and stirred for 5 minutes, 12.585 g of a 48 wt% NaOH aqueous solution was added dropwise at 150 g / min (0.07 mol / L Li and PO in terms of Li ₃ PO _{4). The} solution was stirred at a temperature of 20 ° C. for 12 hours to obtain a mixed solution A ¹ per 1 L of the mixed solution in which ₄ was dissolved.

Mixing a solution A ¹ was solid-liquid separated through a filter press, the obtained solid content, 1 part by mass, and washed with water 10 parts by weight. The washed solid was vacuum-dried at 20 ° C. for 12 hours to obtain Li ₃ PO ₄ particles. The obtained Li ₃ PO ₄ particles had an average secondary particle size of 3.5 μm, a BET specific surface area by nitrogen adsorption of 59.2 m ² / g, and an S content of 0.204 mass%.
11.579 g of the obtained Li ₃ PO ₄ particles and 30 mL of water were mixed and stirred for 5 minutes while maintaining the temperature at 20 ° C. Then, 19.286 g of MnSO ₄ .5H ₂ O and 5.560 g of FeSO ₄ .7H ₂ O were added. This was added to obtain a slurry liquid A ¹ having a pH of 4.0. At this time, the molar ratio of Mn to Fe added was 80:20, and the molar ratio of PO ₄ ions to SO ₄ ions (PO ₄ : SO ₄ ) in the slurry liquid A ¹ was 1.1: 1. The molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) was 2.2: 1.
Next, the slurry liquid A ¹ was put into an autoclave and subjected to a hydrothermal reaction at 170 ° C. for 0.5 hour. The pressure in the autoclave was 0.8 MPa.

The suspension obtained by the hydrothermal reaction was allowed to cool naturally, followed by solid-liquid separation with a filter press, and the entire separated liquid phase was recovered. Next, the solid content remaining in the filter press was washed by spraying 12 parts by mass of water with respect to 1 part by mass of the solid content, and then the filter was pressed to collect the entire amount of washing water, which was collected first. Mixed with the liquid phase of the hydrothermal reaction.
The washed solid content is vacuum-dried at a normal temperature of 50 Pa to obtain a final target lithium manganese iron phosphate positive electrode active material, which is a positive electrode material, a lithium manganese iron phosphate compound A ¹ (LiMn _0.8 Fe _0.2 PO ₄ ) was obtained.
Table 1 shows various physical properties of Li ₃ PO ₄ particles, slurry liquid A ¹ and positive electrode active material A ¹ .

The obtained lithium iron manganese phosphate compound A ^{1 (} 3.0 g) and glucose (0.405 g) were mixed in advance to obtain a mixture. The obtained mixture was put into a planetary mill (P-5, manufactured by Fritsch), and mixed and ground at 400 rpm for 15 minutes.
Next, using an electric furnace purged with argon hydrogen (hydrogen concentration: 3%) gas, the obtained particles were fired at a temperature of 700 ° C. for 1 hour to obtain a positive electrode active material A ¹ . The obtained positive electrode active material A ^{1 had} a crystallite diameter of 48 nm, a BET specific surface area by nitrogen adsorption of 22.7 m ² / g, and an S content of 0.51% by mass.

[Example 2]
Except that 11.925g of 75% aqueous solution of phosphoric acid amount when added to the solution A2, and the dripping aqueous NaOH 14.873G, in the same manner as in Example 1, mixed in place of the mixed solution A ¹ Solution A ² was obtained to obtain Li ₃ PO ₄ particles. Next, a hydrothermal reaction was carried out in the same manner as in Example 1 to obtain lithium manganese iron phosphate compound A ² (LiMn _0.8 Fe _0.2 PO ₄ ). Then, using the obtained manganese phosphate iron lithium compound A ^2, to obtain a positive electrode active material A ² in the same manner as in Example 1.
Table 1 shows various physical properties of Li ₃ PO ₄ particles, slurry liquid A ² and positive electrode active material A ² .

[Example 3]
Except that 13.760g of 75% aqueous solution of phosphoric acid amount when added to the solution A2, and the dripping aqueous NaOH 17.162G, in the same manner as in Example 1, mixed in place of the mixed solution A ¹ Solution A ³ was obtained to obtain Li ₃ PO ₄ particles. Next, a hydrothermal reaction was carried out in the same manner as in Example 1 to obtain lithium manganese iron phosphate compound A ³ (LiMn _0.8 Fe _0.2 PO ₄ ). Next, a positive electrode active material A ³ was obtained in the same manner as in Example 1 by using the obtained lithium iron manganese phosphate compound A ³ .
Table 1 shows various physical properties of the Li ₃ PO ₄ particles, the slurry liquid A ³ and the positive electrode active material A ³ .

[Example 4]
Except that 9.632g of 75% aqueous solution of phosphoric acid amount when added to the solution A2, and the dripping aqueous NaOH 12.013G, in the same manner as in Example 1, mixed in place of the mixed solution A ¹ Solution A ⁴ was obtained to obtain Li ₃ PO ₄ particles. Next, a hydrothermal reaction was carried out in the same manner as in Example 1 to obtain lithium manganese iron phosphate compound A ⁴ (LiMn _0.8 Fe _0.2 PO ₄ ). Then, a manganese phosphate lithium iron compound A ⁴ obtained using, to obtain a positive electrode active material A ⁴ in the same manner as in Example 1.
Table 1 shows the physical properties of Li ₃ PO ₄ particles, slurry liquid A ⁴ and positive electrode active material A ⁴ .

[Comparative Example 1]
Except that 9.173g of 75% aqueous solution of phosphoric acid amount when added to the solution A2, and the dripping aqueous NaOH 11.441G, in the same manner as in Example 1, mixed in place of the mixed solution A ¹ Solution A ⁵ was obtained to obtain Li ₃ PO ₄ particles. Next, a hydrothermal reaction was carried out in the same manner as in Example 1 to obtain lithium manganese iron phosphate compound A ⁵ (LiMn _0.8 Fe _0.2 PO ₄ ). Next, a positive electrode active material A ⁵ was obtained in the same manner as in Example 1 by using the obtained lithium manganese iron phosphate compound A ⁵ .
Table 1 shows the physical properties of Li ₃ PO ₄ particles, slurry liquid A ⁵ and positive electrode active material A ⁵ .

[Comparative Example 2]
Except that 9.448g of 75% aqueous solution of phosphoric acid amount when added to the solution A2, and the dripping aqueous NaOH 11.784G, in the same manner as in Example 1, mixed in place of the mixed solution A ¹ Solution A ⁶ was obtained to obtain Li ₃ PO ₄ particles. Next, a hydrothermal reaction was carried out in the same manner as in Example 1 to obtain lithium manganese iron phosphate compound A ⁶ (LiMn _0.8 Fe _0.2 PO ₄ ). Then, using a manganese phosphate lithium iron compound A ⁶ obtained in the same manner as in Example 1 to obtain a positive electrode active material A ^6.
Table 1 shows various physical properties of Li ₃ PO ₄ particles, slurry liquid A ⁶ and positive electrode active material A ⁶ .

<Evaluation of charge / discharge characteristics>
Using the positive electrode active materials A ^{1 to} A ⁶ obtained in Examples 1 to 4 and Comparative Examples 1 to 2, positive electrodes of lithium ion secondary batteries were produced. Specifically, the obtained positive electrode active material, ketjen black and polyvinylidene fluoride were mixed at a weight ratio of 90: 3: 7, and N-methyl-2-pyrrolidone was added thereto and kneaded sufficiently. A positive electrode slurry was prepared. The positive electrode slurry was applied to a current collector made of an aluminum foil having a thickness of 20 μm using a coating machine, and vacuum dried at 80 ° C. for 12 hours. Thereafter, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.

  Next, a coin-type lithium ion secondary battery was constructed using the positive electrode. A lithium foil punched to φ15 mm was used for the negative electrode. As the electrolytic solution, a solution obtained by dissolving LiPF6 at a concentration of 1 mol / L in a mixed solvent in which ethylene carbonate and ethylmethyl carbonate were mixed at a volume ratio of 1: 1 was used. As the separator, a known one such as a polymer porous film such as polypropylene was used. These battery components were assembled and housed in a conventional manner in an atmosphere with a dew point of −50 ° C. or lower to produce a coin-type lithium ion secondary battery (CR-2032).

A charge / discharge test at a constant current density was performed using the manufactured lithium ion secondary battery. The charging conditions at this time were constant current charging with a current of 0.1 CA (17 mAh / g) and a voltage of 4.5V. The discharge conditions were a current of 0.1 CA and a constant current discharge with a final voltage of 2.0V. All temperatures were 30 ° C.
Table 1 shows the results of the obtained discharge capacity.

From the results shown in Table 1, the molar ratio of PO ₄ ions and SO ₄ ions in the slurry liquid subjected to the hydrothermal reaction (PO ₄₎ even when the metal sulfate is used as the raw metal source while recycling the waste liquid. ₄ : SO ₄ ) and Examples 1 to _{4 in} which the molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) satisfies the requirements have a discharge capacity equivalent to that of Comparative Example 1 or 2. However, it can be seen that the S content in the lithium manganese phosphate positive electrode active material can be effectively reduced.

Claims (8)

LiFe _a Mn _b M _c PO ₄ (M represents Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd, or Gd, and a, b, and c are 0. ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 0.3, and 2a + 2b + (the valence of M) × c = 2 and a number satisfying a + b ≠ 0. Type lithium phosphate positive electrode material manufacturing method,
Step (I) of mixing a solution in which a lithium compound is completely dissolved and a solution in which a lithium compound and a phosphate compound are completely dissolved to obtain a mixed solution;
A step (II) in which an alkaline solution is dropped into the mixed solution obtained in the step (I) to obtain Li ₃ PO ₄ particles;
The Li ₃ PO ₄ particles obtained in step (II) are washed, and then a metal sulfate or a hydrate thereof is added and mixed to obtain a slurry liquid, which is then subjected to a hydrothermal reaction to obtain a reaction mixture. Step (III),
Separating the solution containing unreacted Li ions from the reaction mixture obtained in step (III) to obtain an olivine-type lithium phosphate-based positive electrode material (IV),
In step (I), the solution containing unreacted Li ions separated in step (IV) is used as all or part of the solution in which the lithium compound is completely dissolved. In step (III), the PO in the slurry liquid is used. The molar ratio of ₄ ions to SO ₄ ions (PO ₄ : SO ₄ ) is 1.05: 1 to 2: 1, and the molar ratio of alkali to SO ₄ ions (alkali: SO ₄ ) is 2.1: The manufacturing method of the olivine type lithium phosphate positive electrode material which is 1-4: 1. The olivine type lithium phosphate positive electrode material according to claim 1, wherein the cleaning of the Li ₃ PO ₄ particles in the step (III) is a cleaning using 5 to 100 parts by mass of water with respect to 1 part by mass of the Li ₃ PO ₄ particles. Manufacturing method.   The method for producing an olivine-type lithium phosphate positive electrode material according to claim 1 or 2, wherein the alkali is sodium hydroxide.   The olivine type phosphoric acid according to any one of claims 1 to 3, wherein the content of the lithium compound in the solution in which the lithium compound used in the step (I) is completely dissolved is 0.1 to 33 g / L. A method for producing a lithium-based positive electrode material.   The total content of the lithium compound and the phosphate compound in the solution in which the lithium compound and the phosphate compound used in the step (I) are completely dissolved is 10 to 1500 g / L. The manufacturing method of the olivine type lithium phosphate positive electrode material of description. Claim S weight of the resulting Li ₃ PO ₄ particles in step (II) is a ^{_{Li 3 PO 4 1 × 10 -6}} ~6 × respect BET specific surface area per particle 1g ¹⁰ -5 g / m ² The manufacturing method of the olivine type lithium phosphate positive electrode material of any one of 1-5. The method for producing an olivine-type lithium phosphate positive electrode material according to any one of claims 1 to 6, wherein the BET specific surface area of the Li ₃ PO ₄ particles obtained in the step (II) is 20 to 150 m ² / g. .   The method for producing an olivine-type lithium phosphate positive electrode material according to any one of claims 1 to 7, wherein the lithium compound used in step (I) is lithium carbonate.