JP6151386B2 - Manufacturing method of olivine type lithium phosphate positive electrode material - Google Patents

Description

  The present invention relates to a method for producing an olivine type lithium phosphate positive electrode material.

  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 proposes a method of recovering Li ₂ CO ₃ by adding Na ₂ CO ₃ after adjusting the pH of the liquid phase after hydrothermal synthesis. However, since the solubility of Li ₂ CO ₃ in water is relatively large, it is difficult to recover all Li ions in the liquid phase by this method.

On the other hand, 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 utilizing the lithium phosphate slurry obtained in the fourth step for the first step, unreacted Li is recovered and reused.

JP 2008-66019 A

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

However, in the method described in Patent Document 1, a solid phase Li source is added to the liquid phase after hydrothermal synthesis in the fourth step of generating Li ₃ PO ₄ . Since the pH is increased by the addition, a part of the added Li source remains undissolved. This is also clear from the fact that it is described as Li ₃ PO ₄ + etc. in FIG. Furthermore, Li ₃ PO ₄ produced by the method described in this document is a product in a liquid-solid reaction between the liquid phase after hydrothermal synthesis and the added solid-phase Li source, and thus Li ₃ produced The PO ₄ particles have irregular particle sizes, and the particles are likely to be coarse.

Therefore, even if an olivine-type lithium phosphate positive electrode material is synthesized by using a lithium phosphate slurry containing not only Li ₃ PO ₄ particles but also a solid phase other than Li ₃ PO ₄ as one of the raw materials, such a positive electrode material is used. The particle size of the product itself is also coarsened, and good battery characteristics may not be exhibited in the obtained battery.

  Therefore, an object of the present invention is a method for producing an olivine-type lithium phosphate positive electrode material that undergoes a solid-liquid separation step after subjecting a specific raw material containing a lithium compound or the like to a hydrothermal reaction, and has a small particle size. It is another object of the present invention to provide a production method in which a positive electrode material having high uniformity can be obtained and the drainage liquid obtained in the process can be used again as a raw material. However, it is necessary to avoid an increase in the amount of adsorbed moisture of the positive electrode active material to such an extent that the particle size of the obtained olivine-type lithium phosphate positive electrode material is excessively reduced and the battery characteristics are deteriorated.

Accordingly, the present inventors have made various studies and have found that olivine-type phosphorous undergoes a specific hydrothermal reaction step and a solid-liquid separation step through a so-called liquid-liquid reaction using a solution in which a lithium compound or the like is completely dissolved. A liquid-liquid in a liquid mixture by a liquid phase after hydrothermal synthesis and a liquid phase of a stoichiometric component complementation for generating Li ₃ PO ₄ by adopting a method for producing a lithium acid-based positive electrode material The present inventors have found that Li ₃ PO ₄ particles that are controlled to an appropriate particle size and have high uniformity can be generated while allowing reuse of the drainage liquid by reaction, and have completed the present invention.

That is, the present invention _{is, LiFe a Mn b M c PO} 4 ( provided that, M is Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, and 0 ≦ c ≦ 0.3), a method for producing an olivine-type lithium phosphate positive electrode material,
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;
Step (III) in which Li ₃ PO ₄ particles obtained in Step (II) are washed, and then a metal source is added and mixed, followed by hydrothermal reaction to obtain a reaction mixture;
Separating the solution containing unreacted Li ions from the reaction mixture obtained in step (III) to provide an olivine-type lithium phosphate-based positive electrode material (IV),
The present invention provides a method for producing an olivine-type lithium phosphate positive electrode material.

  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. Olivine-type phosphoric acid, which is obtained after hydrothermal reaction and is controlled to an appropriate particle size and has high homogeneity, while enabling the reuse of wastewater that has been only a target of conventional disposal. Since a lithium-based positive electrode material can be produced, it is possible to provide a positive electrode material having good battery characteristics while using lithium, which is a rare valuable substance, without waste.

2 is an SEM image showing particles of lithium manganese iron phosphate compound A obtained in Example 1. FIG. 2 is a SEM image showing particles of lithium manganese iron phosphate compound B obtained in Example 2. FIG. 3 is a SEM image showing particles of lithium manganese iron phosphate compound C obtained in Example 3. FIG. 4 is a SEM image showing particles of lithium manganese iron phosphate compound D obtained in Example 4. FIG. 2 is a SEM image showing particles of lithium manganese iron phosphate compound E obtained in Comparative Example 1.

Hereinafter, the present invention will be described in detail.
Method for producing an olivine-type lithium phosphate based cathode material of the present _{invention, LiFe a Mn b M c PO} 4 ( provided that, M is Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La , Ce, Nd or Gd, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, and 0 ≦ c ≦ 0.3), and a method for producing an olivine type lithium phosphate positive electrode material,
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;
Step (II) of obtaining Li ₃ PO ₄ particles having a controlled particle size by dropping an alkaline solution into the mixed solution obtained in Step (I);
Step (III) in which Li ₃ PO ₄ particles obtained in Step (II) are washed, and then a metal source is added and mixed, followed by hydrothermal reaction to obtain a reaction mixture;
A step (IV) is provided in which a solution containing unreacted Li ions is separated from the reaction mixture obtained in step (III) to obtain an olivine-type lithium phosphate positive electrode material.

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 5000 μm or less, and more preferably 1000 μm 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. It means that the solution is highly transparent, and is a liquid substance different from the so-called slurry.

  The solution A1 preferably contains 1.8 to 2.2 mol of lithium, more preferably 1.9 to 2.1 mol, relative to 1 mol of phosphorus in the other solution A2. What is necessary is just to use the said lithium compound so that it may become quantity. For example, the content of the lithium compound in the solution A1 is preferably 100 to 33000 mg / L, and more preferably 1000 to 33000 mg / L.

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 15000 to 20000 mg / L, and more preferably 16000 to 18000 mg / L.
The lithium content (g) required for the solution A1 in the step (I) is the lithium content (g) in the liquid phase in the reaction mixture obtained by hydrothermal reaction in the step (III) described later. Since the level is equivalent, a solution containing unreacted Li ions obtained in the subsequent solid-liquid separation step (IV) (hereinafter, also referred to as “drainage obtained in step (IV)”) is used as the solution A1. It can be used as a whole or a part.

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 design concentration at the time of preparing the solution A1 may be used. When using the drainage liquid obtained in the step (IV) for the solution A1, the lithium concentration can be measured by using a general analysis method such as ICP emission spectroscopy or ion chromatography. .
Furthermore, when utilizing the drainage liquid obtained in step (IV), the concentration of impurities such as SO ₄ ions (mg / L) in the drainage liquid is also measured in order to determine the amount of alkali to be described later. 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.

  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. Moreover, as the solution A1 used in the step (I), when the effluent obtained in the step (III) described later is used, the purity of the Li ₃ PO ₄ particles is reduced or contaminated by impurities such as SO ₄ ions in the effluent. It can also be prevented. By dripping such an alkaline solution, hardly soluble Li ₃ PO ₄ particles are formed, and impurities such as SO ₄ ions brought from the effluent become readily soluble products in water. Li ₃ PO ₄ particles having a preferred particle size can be efficiently produced.

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. Further, the dropping rate of the alkaline solution for obtaining Li ₃ PO ₄ particles having a preferable particle diameter is preferably about 1 L of a mixed solution in which 0.6 mol / L Li and PO ₄ are dissolved in terms of Li ₃ PO _4. Is 0.05 to 1.0 mol / min, more preferably 0.25 to 0.70 mol / min.

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, when using the drainage liquid obtained in step (III), the molar amount of alkali in the alkali solution is used from the viewpoint of making impurities such as SO ₄ ions in the drainage liquid easily soluble in water. The amount is preferably 2 to 3 times, more preferably 2 to 2.5 times the molar amount of SO ₄ ions or the like in the drainage.

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. Examples of the apparatus used for solid-liquid separation include a filter press machine, a centrifugal filter, and a vacuum filter. 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 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 diameter of the Li ₃ PO ₄ particles, and the particle diameter is preferably 100 nm or more, and more preferably 250 nm or more. The average particle size of the Li ₃ PO ₄ particles is preferably 1 to 10 [mu] m, more preferably 1 to 6 m.

The step (III) provided by the present invention is a step of washing the Li ₃ PO ₄ particles obtained in the step (II), adding and mixing a metal source, and then subjecting to a hydrothermal reaction to obtain a reaction mixture. is there. 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. Thus, by washing with an excessive amount of water, an olivine-type lithium phosphate positive electrode material that exhibits excellent battery properties even when using the drainage liquid obtained in step (III) is obtained. Can do.

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 source used in the step (III) include a metal compound containing an iron compound and / or a manganese compound. The iron compound may be a divalent iron compound or a hydrate thereof, for example, a halide such as iron halide; a sulfate such as iron sulfate; an organic acid salt such as iron oxalate or iron acetate. As well as hydrates thereof. Especially, it is preferable to use iron sulfate or its hydrate from a viewpoint of improving a battery physical property, and a viewpoint of utilizing effectively the drainage liquid obtained at process (III).

  The manganese compound may be a divalent manganese compound or a hydrate thereof, for example, a halide such as manganese halide; a sulfate such as manganese sulfate; an organic acid salt such as manganese oxalate or manganese acetate; And hydrates of these. Especially, it is preferable to use manganese sulfate or its hydrate from a viewpoint of improving battery physical properties, and a viewpoint of utilizing effectively the drainage liquid obtained at process (III).

  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.), And the like, as well as iron compounds and manganese compounds, for example, halides, sulfates, organic acid salts, and hydrates thereof. Among these, from the viewpoint of improving battery physical properties, it is preferable to use a sulfate or a hydrate thereof, and it is more preferable to use a metal (M) sulfate in which M is Mg or Zr.

  When both an iron compound and a manganese compound are used as the metal compound, the molar ratio (manganese compound: iron compound) is preferably 99: 1 to 51:49, more preferably 95: 5 to 55:45. More preferably, it is 90: 10-60: 40.

A metal source such as a metal compound containing the iron compound and / or manganese compound is added to and mixed with the Li ₃ PO ₄ containing mixture composed of Li ₃ PO ₄ particles washed with water and water, and subjected to a hydrothermal reaction. To produce a mixture. The order of adding such metal sources is not particularly limited.
Before mixing the metal source to the Li ₃ PO ₄ containing mixture, 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.

Next, a metal source is added to and mixed with the Li ₃ PO ₄ -containing mixture. The mixing of the metal source is performed while stirring the mixture containing Li ₃ PO ₄ . The pH of such a mixture is preferably 3.5-8, more preferably 4-7. The total amount of these metal sources added is preferably 0.98 to 1.02 mol, more preferably 0.99 to 1.01 mol, with respect to 1 mol of Li ₃ PO ₄ contained in the mixture. is there.

The obtained mixture containing Li ₃ PO ₄ and a metal source 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 when producing a mixture containing Li ₃ PO ₄ and a metal source is contained in the mixture from the viewpoints of solubility of the metal source, easiness of stirring, efficiency of synthesis, and the like. to li ₃ PO ₄ 1 mol, preferably 10 to 30 moles, more preferably 12.5 to 25 mol.
Moreover, you may add antioxidant to the mixture 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. From the viewpoint of preventing the formation of a compound that becomes an olivine-type lithium phosphate-based positive electrode material when added in an excessive amount, the antioxidant is preferably added in an amount of 0.1 to 1 mol of the metal source. It is 01-1 mol, More preferably, it is 0.03-0.5 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, it is preferable to collect all of the washed water and use it as the solution A1 in step (I) together with the solution obtained by solid-liquid separation. . In order to efficiently collect the washing water, it is preferable to perform washing and solid-liquid separation using a filter press machine. The recovered water obtained does not need to be contaminated by impurities before being 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 average particle diameter of the olivine type lithium phosphate positive electrode material is preferably 10 to 80 nm, and more preferably 30 to 50 nm.

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 and 0 ≦ b ≦ 1 and 0 ≦ c ≦ 0.3 are satisfied, and a and b are not 0 at the same time, and 2a + 2b + (valence of M) × c = 2.
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 + (M valence) × c = 2. 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 an object to be processed.

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 avoids an excessively small particle size of the olivine-type lithium phosphate-based positive electrode material and is controlled to an appropriate particle size. Effectively reduced. Specifically, the amount of adsorbed moisture 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 2000 ppm or less, more preferably 1500 ppm or less in the positive electrode active material. It is. The amount of adsorbed moisture is such that moisture is adsorbed until equilibrium is reached at a temperature of 20 ° C. and a relative humidity of 50%, the temperature is raised to 150 ° C. and held for 20 minutes, and further raised to a temperature of 250 ° C. Measured as the amount of water volatilized from the start point to the end point, starting from when the temperature rise is resumed from 150 ° C. when held for 20 minutes and ending at the constant temperature state at 250 ° C. The amount of moisture adsorbed on the positive electrode active material and the amount of water volatilized between the start point and the end point are regarded as the same amount, and the measured value of the volatilized water amount is adsorbed on the positive electrode active material. Moisture content.
Thus, since the positive electrode active material using the olivine type lithium phosphate positive electrode material obtained from the production method of the present invention hardly adsorbs moisture, the amount of adsorbed water without requiring strong drying conditions as a production environment Can be effectively reduced, and the obtained lithium ion secondary battery can stably exhibit excellent battery characteristics even under various usage environments.
When water is adsorbed until equilibrium is reached at a temperature of 20 ° C. and a relative humidity of 50%, the temperature is raised to 150 ° C. and held for 20 minutes, and further raised to a temperature of 250 ° C. and held for 20 minutes. The amount of water volatilized between the start point and the end point, starting from when the temperature rise is resumed from 150 ° C. and the end point when the constant temperature state at 250 ° C. is completed, is measured using a Karl Fischer moisture meter, for example. Can be measured.

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.
About the solution (solution A1) in which the lithium-containing effluent A recovered from the hydrothermal synthesis and the cleaning water recovered from the above washing step were mixed, the Li concentration measured by ICP emission spectroscopy was 8500 mg / L, and the S concentration was 61500 mg. / L.

<< Manufacture of cathode material >>
A preliminary solution was obtained by mixing 3.732 g of Li ₂ CO ₃ and 30 mL of water. Next, 13.67 g of 75% aqueous phosphoric acid solution was added dropwise at 35 mL / min while stirring the obtained preliminary solution for 3 minutes while maintaining the temperature at 20 ° C. Thereafter, the mixture was stirred until Li ₂ CO ₃ was completely dissolved and the solution became transparent to obtain a solution A2.
After 168 mL of solution A1 was added to this solution A2 and stirred for 5 minutes, 28.95 g of 31% NaOH aqueous solution was added dropwise at 150 mL / min (0.6 mol / L Li and PO in terms of Li ₃ PO _{4). The} mixed solution A was obtained by stirring for 12 hours at a temperature of 20 ° C., corresponding to a dropping rate of 5 mol / min per liter of the mixed solution in which ₄ was dissolved.

The mixed solution A was subjected to solid-liquid separation with a filter press, and washed with 10 parts by mass of water with respect to 1 part by mass of the obtained solid content. The washed solid content was vacuum-dried at 20 ° C. for 12 hours to obtain Li ₃ PO ₄ . The obtained Li ₃ PO _{4 had} a maximum particle size of 11 μm, an average particle size of 5 μm, and a BET specific surface area of 49.7 m ² / g by nitrogen adsorption.
11.579 g of the obtained Li ₃ PO ₄ and 30 mL of water were mixed, stirred for 5 minutes while maintaining the temperature at 20 ° C., and then added 19.286 g of MnSO ₄ .5H ₂ O and 5.560 g of FeSO ₄ .7H ₂ O. Thus, a mixture A having a pH of 4.0 was obtained. At this time, the molar ratio of added Mn and Fe was 80:20.
Next, the above mixture A 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 room temperature under a condition of 50 Pa to obtain a final target lithium manganese iron phosphate positive electrode active material, which is a positive electrode material, which is a manganese iron phosphate lithium compound A (LiMn _0.8 Fe _0.2 PO ₄ ) was obtained. The obtained lithium iron manganese phosphate compound A had an average particle size of 30 nm and a BET specific surface area of 28.9 m ² / g by nitrogen adsorption.
The SEM image of the obtained lithium manganese iron phosphate compound A is shown in FIG.

3.0 g of the obtained lithium manganese iron phosphate compound A and 0.405 g of glucose were mixed in advance to obtain a mixture. The obtained mixture was put into a fine particle composite apparatus Nobilta (NOB-130, manufactured by Hosokawa Micron Corporation, power 5.5 kw), the processing temperature was 25 to 35 ° C., the impeller peripheral speed was 30 m / s, and the processing time was 15 minutes. Were mixed to obtain composite particles.
Subsequently, 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.

[Example 2]
<Manufacture of lithium-containing drainage>
LiOH.H ₂ O (4.934 kg) and water (11.705 L) were mixed to obtain a preliminary solution. Subsequently, 5.096 kg of 75% phosphoric acid aqueous solution was added dropwise at 100 mL / min while stirring the obtained preliminary solution at a temperature of 20 ° C. for 5 minutes, followed by stirring at a temperature of 20 ° C. for 12 hours. Solution B containing Li ₃ PO ₄ was obtained.

Next, 4.614 kg of FeSO ₄ .7H ₂ O was added to the total amount of the solution B containing Li ₃ PO ₄ to obtain a mixed solution having a pH of 11.7.

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 with a filter press device to obtain a liquid component (lithium-containing drainage B).
Additionally, solids (iron phosphate lithium compound (LiFePO ₄₎₎ with respect to 1 part by weight, and washed with 12 parts of water.
About the solution (solution B1) in which the lithium-containing effluent B recovered from the hydrothermal synthesis and the cleaning water recovered from the above-described cleaning step are mixed, the Li concentration measured by ICP emission spectroscopy is 7400 mg / L, and the S concentration is 54700 mg. / L.

<< Manufacture of cathode material >>
A preliminary solution was obtained by mixing 9.330 g of Li ₂ CO ₃ and 25 mL of water. Subsequently, 32.670 g of 75% phosphoric acid aqueous solution was dropped at 35 mL / min while stirring the obtained preliminary solution for 3 minutes while maintaining the temperature at 20 ° C. Thereafter, the mixture was stirred until Li ₂ CO ₃ was completely dissolved and the solution became transparent to obtain a solution B2.
In such solutions B2, after the solution B1 was stirred 470mL added to 5 minutes, it was added dropwise 48% aqueous NaOH solution 44.550g at 300 mL / min (Li ₃ PO ₄ converted at the 0.6 mol / L Li and PO ₄ Is equivalent to an addition rate of 15 mol / min per liter of the mixed solution in which is dissolved) and stirred at a temperature of 20 ° C. for 5 minutes to obtain a mixed solution B.

The mixed solution B was subjected to solid-liquid separation with a Buchner funnel, and washed with 10 parts by mass of water with respect to 1 part by mass of the obtained solid content. The washed solid was dried at 80 ° C. for 12 hours to obtain Li ₃ PO ₄ . The obtained Li ₃ PO _{4 had} a maximum particle size of 10 μm, an average particle size of 3.5 μm, and a BET specific surface area of 52.0 m ² / g by nitrogen adsorption.
12.752 g of the obtained Li ₃ PO ₄ and 30 mL of water were mixed, stirred for 5 minutes while maintaining the temperature at 20 ° C., and then 11.831 g of MnSO ₄ .H ₂ O and 8.340 g of FeSO ₄ .7H ₂ O were added. The mixture B was added to obtain a mixture B having a pH of 5.0. At this time, the molar ratio of added Mn and Fe was 70:30.
Next, the mixture F 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 naturally cooled, then solid-liquid separated with a Buchner funnel, and washed with 12 parts by mass of water with respect to 1 part by mass of the obtained solid content. The washed solid content is dried at 80 ° C. for 12 hours to obtain a final target product, lithium iron manganese phosphate positive electrode active material, lithium manganese iron phosphate compound B (LiMn _0.7 Fe _0.3 PO ₄ ). Got. The obtained lithium iron manganese phosphate compound B had an average particle size of 26 nm and a BET specific surface area of 36.4 m ² / g by nitrogen adsorption.
The SEM image of the obtained lithium manganese iron phosphate compound B is shown in FIG.

3.0 g of the obtained lithium iron manganese phosphate compound B, 0.405 g of glucose, 28 mL of ethanol and 2 mL of water were mixed and mixed for 1 hour in a ball mill.
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 B.

[Example 3]
48% NaOH aqueous solution was dropped at 100 mL / min (corresponding to an addition rate of 5 mol / min per liter of a mixed solution in which 0.6 mol / L Li and PO ₄ are dissolved in terms of Li ₃ PO ₄ ), In the same manner as in Example 2, Li ₃ PO ₄ was obtained. The obtained Li ₃ PO _{4 had} a maximum particle size of 12 μm, an average particle size of 4.2 μm, and a BET specific surface area of 34.1 m ² / g by nitrogen adsorption.
Thereafter, in the same manner as in Example 2, to obtain a manganese iron phosphate lithium compound _{C (LiMn 0.7 Fe 0.3 PO 4} ). The obtained lithium iron manganese phosphate compound C had an average particle size of 32 nm and a BET specific surface area of 33.8 m ² / g by nitrogen adsorption.
The SEM image of the obtained lithium manganese iron phosphate compound C is shown in FIG.
Using the obtained lithium manganese iron phosphate compound C, a positive electrode active material C was obtained in the same manner as in Example 2.

[Example 4]
48% NaOH aqueous solution was dropped at 30 mL / min (corresponding to an addition rate of 1.5 mol / min per liter of a mixed solution in which 0.6 mol / L Li and PO ₄ are dissolved in terms of Li ₃ PO ₄ ); Except that, Li ₃ PO ₄ was obtained in the same manner as in Example 2. The obtained Li ₃ PO _{4 had} a maximum particle size of 16 μm, an average particle size of 6.8 μm, and a BET specific surface area by nitrogen adsorption of 27.1 m ² / g.
Thereafter, in the same manner as in Example 2, to obtain a manganese phosphate lithium iron compound _{D (LiMn 0.7 Fe 0.3 PO 4} ). The obtained lithium iron manganese phosphate compound D had an average particle size of 42 nm and a BET specific surface area of 26.7 m ² / g by nitrogen adsorption.
The SEM image of the obtained lithium manganese iron phosphate compound D is shown in FIG.
Using the obtained lithium iron manganese phosphate compound D, a positive electrode active material D was obtained in the same manner as in Example 2.

[Comparative Example 1]
The method described in Patent Document 1 was followed. That is, 13.68 g of phosphoric acid aqueous solution was added dropwise to 168 mL of the stirring solution A1 at 35 mL / min. Thereafter, 3.732 g of Li ₂ CO ₃ was mixed and stirred for 10 minutes, then 8.95 g of solid NaOH (granular) was added, and stirring was continued for 12 hours to obtain a mixed solution E. All NaOH dissolved 5 minutes after the addition.
All operations after the solid-liquid separation of Li ₃ PO ₄ from the mixed solution E were the same as in Example 1.
The obtained Li ₃ PO _{4 had} a maximum particle size of 25 μm, an average particle size of 12.0 μm, and a BET specific surface area by nitrogen adsorption of 39.8 m ² / g.
Moreover, the average particle diameter of lithium manganese iron phosphate compound E obtained by hydrothermal synthesis was 50 nm, and the BET specific surface area by nitrogen adsorption was 18.3 m ² / g.
The SEM image of the obtained lithium manganese iron phosphate compound E is shown in FIG.
Using the obtained lithium manganese iron phosphate compound E, a positive electrode active material E was obtained in the same manner as in Example 1.

<Measurement of adsorbed water content>
The adsorbed water content of the positive electrode active materials A to E obtained in Examples 1 to 4 and Comparative Example 1 was measured according to the following method.
About the positive electrode active material (composite particle), after allowing it to stand for 1 day in an environment of a temperature of 20 ° C. and a relative humidity of 50% and adsorbing moisture until reaching equilibrium, raising the temperature to 150 ° C. and holding for 20 minutes, Furthermore, when the temperature is raised to 250 ° C. and held for 20 minutes, the start point is when the temperature rise is resumed from 150 ° C., and the end point is when the constant temperature state at 250 ° C. is finished. The amount of water that volatilized was measured with a Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Electronics Industry Co., Ltd.) and determined as the amount of moisture adsorbed in the positive electrode active material.
The results are shown in Table 1.

<Evaluation of charge / discharge characteristics>
Using the positive electrode active materials A to E obtained in Examples 1 to 4 and Comparative Example 1, positive electrodes for 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 LiPF ₆ at a concentration of 1 mol / L in a mixed solvent in which ethylene carbonate and ethyl methyl 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 or 3 CA, and a constant current discharge with a final voltage of 2.0 V. All temperatures were 30 ° C.
Table 1 shows the results of the obtained discharge capacity.

  From the above results, according to the production method of the olivine type lithium phosphate positive electrode material of the present invention, it is excellent also in a lithium ion secondary battery using a positive electrode material that uses a drainage liquid obtained by a hydrothermal reaction as a raw material again. It can be seen that the battery characteristics are exhibited.

Claims (8)

LiFe _a Mn _b M _c PO ₄ (where M is Mg, Ca, Sr, Y, Zr, Co, Mo, Ba, Pb, Bi, La, Ce, Nd or Gd, 0 ≦ a ≦ 1, 0 ≦ b) ≦ 1, and 0 ≦ c ≦ 0.3 , a and b are not 0 at the same time, and represent a number satisfying 2a + 2b + (M valence) × c = 2. A method for producing a lithium-based positive electrode material,
A solution in which the lithium compound is completely dissolved (solution A1) and a solution in which the lithium compound and the phosphate compound are completely dissolved (solution A2) are mixed , and lithium is added in an amount of 1.8 to 1 mol of phosphorus in the solution A2. Step (I) of obtaining a mixed solution containing 2.2 mol ;
Step (II) in which an alkaline solution selected from ammonia, aqueous ammonia or sodium hydroxide is added dropwise to the mixed solution obtained in step (I) to obtain Li ₃ PO ₄ particles;
The Li ₃ PO ₄ particles obtained in the step (II) are washed, and then contain an iron compound and / or a manganese compound, and a metal (M) compound (M is Mg, Ca, Sr, Y, Zr, Co, Mo (Indicating Ba, Pb, Bi, La, Ce, Nd, or Gd) , adding and mixing a metal source, and then subjecting to a hydrothermal reaction to obtain a reaction mixture (III);
Separating the solution containing unreacted Li ions from the reaction mixture obtained in step (III) to provide an olivine-type lithium phosphate-based positive electrode material (IV) , and
Using the solution containing unreacted Li ions separated in step (IV) as all or part of the solution in which the lithium compound used in step (I) is completely dissolved,
Manufacturing method of olivine type lithium phosphate positive electrode material. 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 content of the lithium compound in the solution in which the lithium compound used in step (I) is completely dissolved is 100 to 220,000 mg / L. . Step in solution lithium compound and phosphoric acid compound was completely dissolved using (I), the total content of the lithium compound and the phosphoric acid compound, any one of claim 1 to 3 which is 15000~20000mg / L The manufacturing method of the olivine type lithium phosphate positive electrode material of description. The method for producing an olivine-type lithium phosphate positive electrode material according to any one of claims 1 to 4 , wherein the metal source used in step (III) is sulfate or a hydrate thereof. The method for producing an olivine-type lithium phosphate positive electrode material according to any one of claims 1 to 5 , wherein the lithium compound used in step (I) is lithium carbonate. The dropping rate of the alkaline solution in the step (II) is 0.05 to 1.0 mol / min per 1 L of the mixed solution in which 0.6 mol / L Li and PO ₄ are dissolved in terms of Li ₃ PO _4. Item 7. The method for producing an olivine-type lithium phosphate positive electrode material according to any one of Items 1 to 6 . The average particle diameter of the obtained Li ₃ PO ₄ particles in the step (II) is, olivine-type method for producing a lithium phosphate-based positive electrode material according to any one of claims 1 to 7, which is 1 to 10 [mu] m.