TW201938481A - Positive electrode active material for lithium ion secondary batteries, positive electrode material for lithium ion secondary batteries, and lithium ion secondary battery - Google Patents

Abstract

The present invention is the production of an olivine-type positive electrode active material having high safety and a high energy density. The present invention is a positive electrode active material for lithium ion secondary batteries, which comprises lithium manganese phosphate or lithium manganese iron phosphate represented by formula 1. LiMnaFebMe1cMe2dPO4 (formula 1) (In formula 1, Me1 and Me2 are independently selected from the group consisting of Cu, Ag2, Mg, Co and Ni; and a to d meet the requirements represented by the following formulae: a+b+c+d = 1, 0.5 ≤ a < 1.0, 0 ≤ b < 0.5, 0 < c+d ≤ 0.03, 0 < c and 0 < d).

Description

Positive electrode active material for lithium ion secondary battery, positive electrode material for lithium ion secondary battery, and lithium ion secondary battery

The present invention relates to a positive electrode active material for a lithium ion secondary battery, a positive electrode material for a lithium ion secondary battery, and a lithium ion secondary battery.

In recent years, the application and size of lithium-ion secondary batteries have been promoted for the purpose of electrifying automobiles or securing emergency power sources.

Lithium-ion secondary batteries can store the other side of huge energy. When a bad situation occurs, the stored energy will be released in a short time, and there is a danger that the battery will catch fire and burn. Therefore, it is also important for lithium ion secondary batteries to improve energy density, but also to improve safety.

It is well known that a positive electrode material has a great influence on the safety of a lithium ion secondary battery. In particular, a positive electrode material called a layered oxide system, which is often used in a smart phone or an electric vehicle, is a material having a high energy density among the positive electrode materials of a lithium ion secondary battery. On the other hand, the release of oxygen in the battery poses a risk of fire, so there is a problem in terms of safety.

On the other hand, it is known that oxygen and phosphorus are covalently bonded to one lithium iron phosphate of an olivine-based positive electrode material that is frequently used in fixed batteries and the like, and therefore, it does not easily emit oxygen, and is relatively stable even at high temperatures. However, its energy density is inferior to that of the layered oxide system, so its application to electric vehicles and the like is limited.

As an olivine-based positive electrode material obtained by increasing the energy density of lithium iron phosphate having an olivine-based crystal structure that is relatively stable even at high temperatures, lithium manganese phosphate is known, but it is difficult to make both lithium ion and electron conductivity low. Lithium manganese phosphate exhibits an energy density that can be expected from theoretical values.

As one of the methods for increasing the energy density of lithium manganese phosphate, it has been studied to replace a part of manganese with another metal element that does not directly contribute to the charge-discharge reaction. In this method, which is also called doping, the detailed mechanism may not be clear, but it is envisaged that with the addition of different elements, the crystal lattice constant of the crystal is locally changed, so that the phosphoric acid generated during charge and discharge The lattice mismatch between lithium manganese and manganese phosphate is alleviated. It is considered that by this moderating effect, the activation energy of the charge-discharge reaction is reduced, and as a result, the energy density is increased.

Furthermore, lithium manganese iron phosphate in which a part of manganese in lithium manganese phosphate is replaced with iron has also been studied. When manganese is replaced with iron, the theoretical discharge capacity (mAh / g) will not change, but the voltage of the discharge corresponding to the iron will decrease, so the theoretical energy density (Wh / kg) will decline. However, since the conductivity is improved by substitution with iron, it is easy to develop an energy density closer to a theoretical value.

In the methods disclosed in Patent Documents 1 to 3, various doping elements for an olivine-based positive electrode material have been studied, and as an effect thereof, energy density improvement can be obtained.

In addition, in Non-Patent Document 1 and Non-Patent Document 2, by simultaneously doping two elements, an effect of improving energy density is obtained.
[Prior Art Literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-190787
[Patent Document 2] International Publication No. 2005/041327
[Patent Document 3] Japanese Patent No. 5381115
[Non-patent literature]

[Non-Patent Document 1]: Materials Letters 173 (2016) P131 (Materials Letters 173 (2016) P131)
[Non-Patent Document 2]: Journal of Nanomaterials Volume 2015, Article ID 970856, 7 pages.

[Problems to be Solved by the Invention]
In the doping of Patent Documents 1 to 3, the effect of increasing the energy density is also obtained in a limited manner. However, all of the doping focuses on the doping of one element, so it is not obtained by doping two kinds of elements simultaneously. The combined effect of elements, it is difficult to say that the effect of doping has been maximized.

In Non-Patent Document 1 and Non-Patent Document 2, although two kinds of elements are doped at the same time, the doping amount thereof is 8% or more of all the transition metal components. Doping elements do not contribute to the charge-discharge reaction. Therefore, when 8% of transition metal elements are doped, the theoretical capacity (mAh / g) of the cathode material decreases by 8%, so it is difficult to achieve high energy density in principle. Furthermore, in these Non-Patent Documents 1 and 2, the positive electrode active material in a state where no doping was performed showed only a capacity that was less than 80% of the theoretical capacity (that is, 136 mAh / g), so it failed at all. Overcome the problem of high resistance.

As a result of active research by the present inventors, in such a positive electrode active material having a problem of high resistance, the capacity expansion space is large, and therefore the effect of doping is easily exhibited, but the positive electrode activity exhibiting more than 80% of the theoretical capacity Even if the same doping is performed in a substance, it is not easy to obtain the same effect.

An object of the present invention is to obtain an olivine-based positive electrode active material having high safety and high energy density. That is, the inventors have used lithium manganese phosphate or lithium manganese iron phosphate that is relatively stable even at high temperatures in the olivine-based positive electrode material for lithium ion secondary batteries. In order to improve the energy density with a small amount of doping, Based on active research.
[Means for solving problems]

The present invention to solve the problem is a positive electrode active material for a lithium ion secondary battery, which contains lithium manganese phosphate or lithium manganese iron phosphate represented by the following formula 1;

LiMn _a Fe _b Me1 _c Me2 _d PO ₄ (Formula 1)

(In Formula 1, Me1 and Me2 are repeatedly selected from the group consisting of Cu, Ag ₂ , Mg, Co, and Ni, and a to d satisfy a + b + c + d = 1, 0.5 ≦ a <1.0, 0 ≦ b <0.5, 0 <c + d ≦ 0.03, 0 <c, 0 <d).
[Effect of the invention]

According to the present invention, an olivine-based positive electrode active material having high safety and high energy density can be obtained. In addition, by using the positive electrode active material of the present invention, the safety and energy density of a lithium ion secondary battery can be improved.

The positive electrode active material for a lithium ion secondary battery of the present invention is one in which the energy density is increased by doping two types of doping elements selected from Cu, Ag, Mg, and Co to lithium manganese phosphate and lithium manganese iron phosphate. In addition, in this specification, even if doped lithium manganese iron phosphate and lithium manganese phosphate are sometimes referred to simply as lithium manganese iron phosphate and lithium manganese phosphate for convenience.

The so-called doping element is a metal element that does not directly contribute to the charge-discharge reaction. For example, the iron in lithium manganese iron phosphate is oxidized and reduced within a range of 3.0 V to 4.5 V (Li ⁺ / Li standard), which is the voltage in the charge and discharge range of lithium manganese phosphate, and contributes to the charge and discharge reaction. Therefore, there is no case where the discharge capacity of the positive electrode active material is reduced due to the added iron. Therefore, iron is not treated as a doping element in this specification. On the other hand, Co or Ni does not oxidize and reduce at a voltage in the charge and discharge range of lithium manganese phosphate, and therefore does not contribute to the charge and discharge reaction. Therefore, Co or Ni is treated as a doping element.

The doping element in the present invention does not directly contribute to the charge-discharge reaction, so the theoretical capacity of the positive electrode active material decreases according to the amount of doping. The theoretical capacity of both lithium manganese phosphate and lithium manganese iron phosphate is 170 mAh / g. However, when 10% of Mn and Fe undergoing redox replacement are replaced with doping elements, the theoretical capacity decreases by X%. However, the actual lithium manganese phosphate and lithium manganese iron phosphate exhibit a lower capacity than the theoretical capacity, so even if the theoretical capacity decreases by X%, if the capacity exceeds X% by doping, it can also be said that the result is doped. effect.

This invention is a positive electrode active material for lithium ion secondary batteries containing lithium manganese phosphate or lithium manganese iron phosphate represented by following formula 1.

LiMn _a Fe _b Me1 _c Me2 _d PO ₄ (Formula 1)

(In Formula 1, Me1 and Me2 are repeatedly selected from the group consisting of Cu, Ag ₂ , Mg, Co, and Ni, and a to d satisfy a + b + c + d = 1, 0.5 ≦ a <1.0, 0 ≦ b <0.5, 0 <c + d ≦ 0.03, 0 <c, 0 <d)
In Formula 1, the doping element Me1 and the doping element Me2 are repeatedly selected from the group consisting of Cu, Ag ₂ , Mg, Co, and Ni. That is, in Formula 1, 0 <c and 0 <d. Although the details of the mechanism that increases the energy density in particular by the combination of this element are not clear, it is thought that the change in the crystal lattice caused by the lithium lithium manganese phosphate and lithium iron manganese phosphate accompanying the detachment and insertion of lithium is large. Disturbance of the strain-like lattice that eases the lattice of the doped element is induced.

Regarding this moderating effect, it is considered that the influence of the ionic radius and the valence when the doping element Me1 and the doping element Me2 are taken into the crystal is large. In particular, an element that is a trivalent ion causes excessive lattice disorder. Therefore, as the doping element Me1 and the doping element Me2, an element that can become a monovalent or divalent ion is preferred. Regarding the two types of doping elements, it is thought that the disordering effect of the lattice is promoted, so that the mitigating effect is further improved. Even if the molar amount is the same as that of the one type of doping, a high energy density is achieved. .

The discharge of lithium manganese iron phosphate includes a discharge at 4 V corresponding to the oxidation of manganese and a discharge at 3.4 V corresponding to the oxidation of iron. However, if the ratio of iron to manganese is excessive, most of the discharge The discharge becomes 3.4 V. In order to obtain higher energy density, it is necessary to discharge at a high voltage. Therefore, it is necessary to set the ratio of iron in lithium manganese iron phosphate to a certain amount or less, such that 0.5 ≦ a <1.0 and 0 ≦ b <0.5.

In addition, since Ag is a monovalent metal, it will not be electrically equivalent unless a molar amount that is twice that of other metals is added. Therefore, in the description of the present invention, in the formula LiMn _a Fe _b Me1 _c Me2 _d PO ₄ , for example, when Me1 is Ag, c and C are determined by the expression LiMn _a Fe _b Ag _2c Me2 _d PO ₄ . Coefficient of d.

The addition amount of the doping element in the present invention is 0 <c + d ≦ 0.03 in Formula 1. The doping element does not undergo redox in the range of 3 V to 4.5 V (Li ⁺ / Li standard), so the theoretical capacity is reduced by the amount added. Therefore, the excessive addition reduces the theoretical capacity and cannot be compensated by the effect of doping. Therefore, the amount of addition to suppress the drop in the theoretical capacity and obtain the effect of doping needs to be in the range described above. In order to exert a higher effect of doping, it is preferably 0 <c + d ≦ 0.015. In addition, in order to sufficiently obtain the effect of doping, it is more preferably 0.005 ≦ c + d.

Regarding the quantification of the amount of doping, in terms of measurement accuracy and reproducibility, it is preferable to use an inductively coupled plasma (ICP) emission spectrometry to measure Mn, Fe, Me1, and Me2. In addition, since Me1 and Me2 are in a trace amount, in order to obtain more reliable accuracy, the measurement is preferably performed three times, and the average value is used. In addition, the concentration of the measurement sample solution can be changed to divide the measurement into several times. In addition, the coefficients of a to d are determined by normalizing so that a + b + c + d = 1.

A preferred doping element of the present invention is Cu or Ag. That is, in Formula 1, it is preferable that either of Me1 and Me2 is Cu or Ag ₂ . Cu or Ag is thought to improve the electronic state peculiar to noble metals and the doping effect of high electron conductivity. Therefore, a better aspect is that the combination of doping elements is Cu and Ag, that is, in Formula 1, Me1 and Me2 are combinations of Cu and Ag ₂ .

Moreover, as a combination of the doping elements of the present invention, it is also preferable that in Formula 1, Me1 and Me2 are Ni and Co. The reason why the combination improves the energy density of the battery is considered to be that the doping of the combination has a particularly high effect of alleviating the gap of the crystals caused by the detachment and insertion of lithium.

The positive electrode active material for a lithium ion secondary battery of the present invention is preferably nano particles. It is known that lithium manganese phosphate and lithium manganese iron phosphate have low lithium ion and electron conductivity, and in order to minimize the influence, it is effective to perform nanoparticle granulation to reduce the solid diffusion distance. These particles that have not been subjected to nanoparticle granulation do not easily undergo a charge-discharge reaction, and therefore the effect of doping tends to be small. Here, the nano particles are particles having an average particle diameter of 70 nm or less. That is, the positive electrode active material for a lithium ion secondary battery of the present invention is preferably nano particles having an average particle diameter of 70 nm or less.

The average particle diameter of the particles is an average of the particle diameters of all the particles in the field of view when the particles are observed at a magnification that includes only 30 or more and 50 or less using a scanning electron microscope. The particle diameter of one particle is an average of the maximum diameter and the minimum diameter of the particles. When the particles are carbon-coated and the weight ratio of carbon is less than 5% by weight of the entire carbon-coated particles, the carbon-coated layer is a few nanometers and is an extremely thin layer. The particle diameter obtained by directly observing the carbon-coated state is the particle diameter of the positive electrode active material.

Furthermore, the positive electrode active material for a lithium ion secondary battery of the present invention may be conductively treated by coating the surface with carbon. In this case, the powder resistance value of the carbon-coated particles is preferably 1 Ω ･ cm or more and 10 ⁸ Ω ･ cm or less. If it is 10 ⁸ Ω ･ cm or more, the electrical resistance from the current collector to the particle surface when the electrode is self-made becomes large, and thus the capacity may be significantly hindered. In this specification, an active material that has been coated with carbon may be simply referred to as an active material.

In order to make full use of the capacity of lithium manganese phosphate and lithium manganese iron phosphate, it is preferable to coat lithium manganese phosphate particles or lithium manganese iron phosphate particles in an amount of 1% to less than 10% by weight in such a carbon-coated state. Carbon is more preferably 1% by weight or more and less than 5% by weight. When an appropriate amount of carbon is coated, the electron conductivity in the electrode is improved when the electrode is made, thereby helping lithium manganese phosphate and lithium manganese iron phosphate to exhibit capacity. On the other hand, if a large amount of carbon is coated, the carbon will hinder lithium ion conduction, and the ion conductivity tends to decrease.

In order to use the positive electrode active material for a lithium ion secondary battery containing lithium manganese phosphate or lithium manganese iron phosphate in the present invention as a positive electrode material for a lithium ion secondary battery, it is preferred that the surface of the lithium ion secondary battery be coated with carbon. The positive electrode active material for a battery is made into a granule structure in the form of secondary particles in which the particles are aggregated. The granulated body containing the positive electrode active material for a lithium ion secondary battery can greatly improve the operability in the process of forming a positive electrode material into a coating film. The granulated body is preferably granulated into a spherical shape, and its particle size is preferably 0.1 μm or more and 30 μm or less. If it is less than 0.1 μm, a large amount of N-methylpyrrolidone as a dispersion medium at the time of coating is required, and a large amount of time and energy is required in the drying step, which is not preferable. In addition, if the particle diameter is 30 μm or more, the surface smoothness of the obtained positive electrode film, which is usually molded into a range of 50 μm to 100 μm, is likely to be lost, which is not preferable. The introduction of the doping element into the particles can be achieved by synthesizing lithium manganese phosphate or lithium manganese iron phosphate particles, mixing the doping element source with the particles, and then heating the particles. Furthermore, as a method of uniformly doping into particles, a method of adding a doping element source as a part of a manganese source during particle synthesis is also preferable.

Regarding the dopant element source which is a raw material of the dopant element, carbonate, phosphate, sulfate, hydrochloride, nitrate, acetate, and acetone acetone can be used, but in particular, the dissolution into water, which is a general-purpose solvent, is considered. Properties, sulfates and acetates are preferred.

The method for carbon coating the lithium manganese phosphate and lithium manganese iron phosphate of the present invention is not particularly limited, and examples thereof include a method in which a ball mill is mixed with carbon such as acetylene black to form a complex, or a method such as combining with a sugar such as glucose or sucrose Method of mixing and simmering. Of the two methods, the latter method is preferable in that a thin layer can be uniformly applied to particles.

In order to make the lithium manganese phosphate and the lithium manganese iron phosphate of the present invention into a granule structure, it is preferable to use a spray dryer to obtain a uniform spherical shape and particle size distribution. In order to further narrow the particle size distribution, a classifier may be used to classify the granules obtained by the spray dryer. As for the classification, in addition to using a screen, there is also a method in which centrifugal separation is performed by using an air flow. The air flow type is preferable in that it is easy to avoid mixing of foreign matter.

The lithium ion secondary battery of the present invention is a lithium ion secondary battery in which the lithium manganese phosphate or lithium manganese iron phosphate of the present invention is used for at least a part of a positive electrode material.

The ferric manganese phosphate and lithium manganese iron phosphate of the present invention can be obtained by a known method such as a solid phase method, a hydrothermal method, and a liquid phase method. However, in terms of obtaining nano-sized particles more easily, the hydrothermal method Or the liquid phase method is preferred.
Examples

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited to these examples.

[Measurement A] Analysis of the crystal structure Regarding the case where the solid obtained by the synthesis is lithium manganese phosphate or lithium manganese iron phosphate, the use of an X-ray diffraction device (D8 ADVANCE manufactured by Bruker) is equivalent to the absence of This was confirmed by checking the crystalline peaks other than LiMnPO ₄ .

[Measurement B] Determination of the elemental ratio of the compound Part of the synthesized lithium manganese phosphate and lithium manganese iron phosphate was decomposed by pure water and dilute nitric acid, and moved to a container. After adding sulfuric acid and heating and decomposing, dilute nitric acid and a small amount The hydrogen peroxide water is heated to dissolve, and the volume is constant. With this solution, three times ICP emission spectrometry (Hitachi High-Technologies (Hitachi High-Tech Science) manufactured PS3520VDDII), determined from the average of 3 the formula _{LiMn a Fe b Me1 c Me2 d} PO 4 of the coefficients a, Coefficient b, coefficient c, and coefficient d.

[Measurement C] Calculation of average particle diameter of inorganic metal nano particles The average particle diameters of synthesized lithium manganese phosphate and lithium manganese iron phosphate are in a powder state, and are measured by a scanning electron microscope (Hitachi High -Tech) S-5500).

[Measurement D] Measurement of carbon amount after carbon coating The carbon amount of the lithium manganese phosphate or lithium manganese phosphate subjected to carbon coating was measured using a carbon-sulfur analyzer EMIA-810W manufactured by HORIBA Corporation.

[Measurement E] Measurement of average particle size of granules The average secondary particle size of lithium manganese iron phosphate or lithium manganese phosphate after granulation is a laser diffraction / scattering type particle size distribution measuring device manufactured by HORIBA LA-920.

[Measurement F] Since the measured energy density of the discharge capacity of the active material is proportional to the discharge capacity, the discharge capacity is used to evaluate the effect of higher energy density.

After mixing acetylene black (Li-400 manufactured by Denka Co., Ltd.) with a binder (Kureha KF polymer (Kureha KF polymer Co., Ltd. L # 9305)), add lithium manganese iron phosphate as an active material or The lithium manganese phosphate was solid-type kneaded using a mortar. At this time, the mass ratio of each material included was 90: 5: 5 for active material: acetylene black: binder. Then, N-methylpyrrolidone was added, and it adjusted so that solid content might be 45 mass%, and obtained the electrode slurry. When the obtained slurry does not have fluidity, N-methylpyrrolidone is appropriately added until the slurry has fluidity.

The obtained electrode slurry was applied to an aluminum foil (thickness: 18 μm) using a doctor blade (300 μm), dried at 80 ° C. for 30 minutes, and then pressed to obtain an electrode plate. The produced electrode plate was cut to a diameter of 15.9 mm to make a positive electrode, a lithium foil cut to a diameter of 16.1 mm and a thickness of 0.2 mm was used as a negative electrode, and Celgard (registered to a diameter of 20 mm was cut (registered Trademark) # 2400 (manufactured by Celgard) as a separator, and a solution containing 1M LiPF ₆ of ethylene carbonate: diethyl carbonate = 3: 7 (volume ratio) was used as an electrolyte , A 2032-type coin-type battery was produced and subjected to electrochemical evaluation.

The measurement was performed with a theoretical capacity of 170 mAh / g, a cut-off potential of 3.0 V, a maximum charge voltage of 4.3 V, and three charge and discharge cycles at a rate of 0.1 C. According to the third discharge The discharge capacity of a coin-type battery was calculated as the discharge capacity (mAh / g) per unit weight of lithium manganese iron phosphate or lithium manganese phosphate.

[Example 1]
200 g of dimethyl sulfene was added to 150 g of pure water, and 120 millimoles of phosphoric acid was added using an 85% phosphoric acid aqueous solution. After adding 360 millimoles of lithium hydroxide monohydrate to the obtained solution, manganese sulfate monohydrate 95.04 millimoles, iron (II) sulfate heptahydrate 23.76 millimoles, and copper sulfate pentahydrate 0.6 millimoles were added. Ear, 1.2 millimoles of silver (I) sulfate. The obtained solution was transferred to an autoclave, and the inside of the solution was heated and maintained at 120 ° C. for 4 hours. The supernatant of the solution was discarded after heating, and lithium iron manganese phosphate was obtained as a precipitate. After the obtained lithium manganese iron phosphate was washed with pure water, the operation of removing the supernatant by centrifugation was repeated 5 times, and finally pure water was added again to prepare a dispersion. A part of the dispersion was dried at 80 ° C. to obtain a sample for analysis, and the results obtained by performing measurement A to measurement C are shown in Table 1.

Next, glucose having the same weight as 15% by weight of lithium manganese iron phosphate in the dispersion was added to the dispersion and dissolved. The obtained dispersion was dried and granulated with a spray dryer (MDL-050B manufactured by Fujisaki Electric Corporation) using hot air at 200 ° C. The obtained powder was heated at 700 ° C. for 4 hours in a rotary kiln (disk top rotary kiln manufactured by Takasago Industries Co., Ltd.) under a nitrogen gas atmosphere to obtain carbon-coated phosphoric acid. Lithium iron manganese.

Measurements D to F were performed using a part of the obtained lithium manganese iron phosphate, and the obtained results are shown in Table 1.

[Example 2]
In Example 1, manganese sulfate monohydrate was changed to 94.08 millimoles, iron (II) sulfate heptahydrate was 23.52 millimoles, copper sulfate pentahydrate was 1.2 millimoles, and silver (I) sulfate was 2.4. Other than mol, lithium manganese iron phosphate was synthesized in the same manner.

[Example 3]
In Example 1, manganese sulfate monohydrate was changed to 93.12 millimoles, iron (II) sulfate heptahydrate was 23.28 millimoles, and silver (I) sulfate was changed to 2.4 millimoles. Way to synthesize lithium manganese iron phosphate.

[Example 4]
In Example 1, manganese sulfate monohydrate was changed to 118.8 millimoles, iron (II) sulfate heptahydrate was changed to 0 millimoles, copper sulfate pentahydrate was changed to 0.6 millimoles, and silver (I) sulfate was changed to 1.2. The temperature in the autoclave during synthesis was changed to 105 ° C, the weight of glucose during carbon coating was 25% by weight of lithium manganese phosphate, and the temperature of the rotary kiln during carbon coating was 600 ° C. Other than that, lithium manganese phosphate was synthesized in the same manner.

[Example 5]
In Example 1, manganese sulfate monohydrate was changed to 71.28 millimoles, iron (II) sulfate heptahydrate was 47.52 millimoles, copper sulfate pentahydrate was 0.6 millimoles, and silver (I) sulfate was 1.2. Other than mol, lithium manganese iron phosphate was synthesized in the same manner.

[Example 6]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that silver (I) sulfate 1.2 mol was changed to cobalt sulphate heptahydrate 0.6 mol.

[Example 7]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that silver (I) sulfate 1.2 mol was changed to nickel sulfate hexahydrate 0.6 mol.

[Example 8]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that silver (I) sulfate 1.2 mol was changed to magnesium sulphate heptahydrate 0.6 mol.

[Example 9]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that the copper sulfate pentahydrate 0.6 mol was changed to cobalt sulfate heptahydrate 0.6 mol.

[Example 10]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that the copper sulfate pentahydrate 0.6 mol was changed to nickel sulfate hexahydrate 0.6 mol.

[Example 11]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that the copper sulfate pentahydrate 0.6 millimoles was changed to magnesium sulfate heptahydrate 0.6 millimoles.

[Example 12]
In Example 1, 0.6 millimoles of copper sulfate pentahydrate was changed to 0.6 millimoles of nickel sulfate hexahydrate, and 1.2 millimoles of silver (I) sulfate was changed to 0.6 millimoles of magnesium sulfate heptahydrate. In the same manner, lithium manganese iron phosphate was synthesized.

[Comparative Example 1]
In Example 1, manganese sulfate monohydrate was changed to 96 millimoles, iron (II) sulfate heptahydrate was changed to 24 millimoles, copper sulfate pentahydrate was changed to 0 millimoles, and silver (I) sulfate was changed to 0. Other than mol, lithium manganese iron phosphate was synthesized in the same manner.

[Comparative Example 2]
In Example 4, manganese sulfate monohydrate was changed to 120 millimoles, copper sulfate pentahydrate was changed to 0 millimoles, and silver (I) sulfate was changed to 0 millimoles, and phosphoric acid was synthesized in the same manner. Manganese lithium.

[Comparative Example 3]
In Example 1, manganese sulfate monohydrate was changed to 0 mmol, iron (II) sulfate heptahydrate was changed to 120 mmol, copper sulfate pentahydrate was changed to 0 mmol, and silver (I) sulfate was changed to 0. Lithium iron phosphate was synthesized in the same manner except that the temperature in the autoclave during synthesis was changed to 200 ° C. and the weight of glucose during carbon coating was 10% by weight of lithium iron phosphate.

[Comparative Example 4]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that the copper sulfate pentahydrate was changed to 1.2 millimoles and the silver (I) sulfate was changed to 0 millimoles.

[Comparative Example 5]
In Example 1, lithium manganese iron phosphate was synthesized in the same manner except that copper sulfate pentahydrate was changed to 0 mmol and silver (I) sulfate was changed to 2.4 mmol.

[Comparative Example 6]
In Example 1, ferric manganese phosphate was synthesized in the same manner except that copper sulfate pentahydrate 0.6 mol was changed to cobalt sulfate heptahydrate 1.2 mol and silver (I) sulfate was 0 mol. lithium.

[Comparative Example 7]
In Example 1, ferric manganese phosphate was synthesized in the same manner, except that 0.6 millimoles of copper sulfate pentahydrate was changed to 1.2 millimoles of nickel sulfate hexahydrate and silver (I) sulfate was changed to 0 millimoles. lithium.

[Comparative Example 8]
In Example 1, ferric manganese phosphate was synthesized in the same manner except that 0.6 millimoles of copper sulfate pentahydrate was changed to 1.2 millimoles of magnesium sulfate heptahydrate, and silver (I) sulfate was changed to 0 millimoles. lithium.

[Comparative Example 9]
In Example 1, manganese sulfate monohydrate was changed to 91.2 millimoles, iron (II) sulfate heptahydrate was 22.8 millimoles, copper sulfate pentahydrate was 3 millimoles, and silver (I) sulfate was 6 Other than mol, lithium manganese iron phosphate was synthesized in the same manner.

[Comparative Example 10]
In Comparative Example 3, except that iron (II) sulfate heptahydrate was 118 millimoles, copper sulfate pentahydrate was 0.6 millimoles, and silver (I) sulfate was 0.6 millimoles. Way to synthesize lithium iron phosphate.

[Comparative Example 11]
In Example 1, manganese sulfate monohydrate was changed to 86.4 millimoles, iron (II) sulfate heptahydrate was 21.6 millimoles, copper sulfate pentahydrate was 6 millimoles, and silver (I) sulfate was sulfuric acid. A lithium manganese iron phosphate was synthesized in the same manner except that aluminum (III) n hydrate was 6 mmol.

[Comparative Example 12]
In Comparative Example 1, lithium manganese iron phosphate was synthesized in the same manner except that 300 g of pure water and 50 g of dimethylsulfinium were changed.

[Comparative Example 13]
In Comparative Example 11, lithium manganese iron phosphate was synthesized in the same manner, except that 300 g of pure water and 50 g of dimethylsulfinium were changed.

For the active material particles synthesized in Examples 2 to 12, and Comparative Examples 1 to 13, the results obtained by performing measurement A to measurement C in the same manner as in Example 1 and the results for each active material particle and Table 1 shows the results obtained by performing measurement D to measurement F on particles obtained by coating carbon in the same manner as in Example 1.

[Table 1]

no

no

Claims (10)

A positive electrode active material for a lithium ion secondary battery, comprising lithium manganese phosphate or lithium manganese iron phosphate represented by the following formula 1; LiMn _a Fe _b Me1 _c Me2 _d PO ₄ (formula 1) In the formula 1, Me1 and Me2 Non-repeatingly selected from the group consisting of Cu, Ag ₂ , Mg, Co, and Ni, a to d satisfy a + b + c + d = 1, 0.5 ≦ a <1.0, 0 ≦ b <0.5, 0 < c + d ≦ 0.03, 0 <c, 0 <d. The positive electrode active material for a lithium ion secondary battery according to item 1 of the scope of application for a patent, wherein in the formula 1, c and d satisfy 0 <c + d ≦ 0.015. The positive electrode active material for a lithium ion secondary battery according to item 1 or item 2 of the scope of patent application, wherein in the formula 1, either of Me1 and Me2 is Cu or Ag ₂ . The positive electrode active material for a lithium ion secondary battery according to item 3 of the scope of patent application, wherein, in Formula 1, Me1 and Me2 are a combination of Cu and Ag ₂ . The positive electrode active material for a lithium ion secondary battery according to item 1 or item 2 of the scope of the patent application, wherein, in Formula 1, Me1 and Me2 are a combination of Co and Ni. The positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 5 of the scope of patent application, which is a nanoparticle having an average particle diameter of 70 nm or less. A positive electrode active material for a lithium ion secondary battery, wherein the surface of the positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 6 is further coated with carbon, and to make. A positive electrode material for a lithium ion secondary battery, comprising the positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 7 of the scope of patent application. The positive electrode material for a lithium ion secondary battery according to item 8 of the patent application scope includes granules formed by assembling the positive electrode active material for a lithium ion secondary battery according to item 7 of the patent application scope. A lithium ion secondary battery using the positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 7 in at least a part of a positive electrode material.