阅读说明：本技术 正极材料及其制造方法、使用上述正极材料的电池及其制造方法以及使用上述电池的电子设备 (Positive electrode material and method for producing same, battery using said positive electrode material and method for producing same, and electronic device using said battery ) 是由 栗田知周 本间健司 肥田胜春 岩田纯一 于 2018-02-14 设计创作，主要内容包括：本发明提供一种正极材料,在使用波长<Image he="70" wi="84" file="DDA0002625153750000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的辐射光的X射线衍射(2θ＝5°～90°)中,在2θ＝13.1°±0.2°、14.0°±0.2°和18.4°±0.2°处具有衍射峰,具有属于空间群P2<Sub>1</Sub>/c的单斜晶的晶体结构,由组成式Li<Sub>2－2x</Sub>Co<Sub>1+x</Sub>P<Sub>2</Sub>O<Sub>7</Sub>(－0.2≤x≤0.2)表示。(The invention provides a positive electrode material with a wavelength of use Has diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light of (a), and belongs to space group P2 1 A monoclinic crystal structure of the formula Li 2－2x Co 1+x P 2 O 7 X is more than or equal to (-0.2) and less than or equal to 0.2).)

1. A positive electrode material characterized by having a wavelength of useHas diffraction peaks at 2 theta of 13.1 DEG + -0.2 DEG, 14.0 DEG + -0.2 DEG and 18.4 DEG + -0.2 DEG in X-ray diffraction of the radiated light of 5 DEG to 90 DEG,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

2. The positive electrode material according to claim 1, wherein the number of oxygen atoms coordinated to a Co atom in the crystal structure is 4 to 5.

3. The positive electrode material according to any one of claims 1 to 2, wherein the lattice constant isAnd β -148.

4. A method for producing a positive electrode material is characterized by producing the following positive electrode material:

at the wavelength of use

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2;

the method for producing the positive electrode material includes a step of heat-treating a mixture of a lithium source, a cobalt source, and a phosphoric acid source.

5. The method for producing a positive electrode material according to claim 4, wherein the temperature at the time of the heat treatment is 420 to 520 ℃.

6. The method for producing the positive electrode material according to any one of claims 4 to 5, wherein the heat treatment is performed in an inert atmosphere.

7. A battery, comprising:

a positive electrode containing a positive electrode material, wherein,

a negative electrode, and

an electrolyte disposed between the positive electrode and the negative electrode;

the positive electrode material is as follows:

at the wavelength of use

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

8. A method for producing a battery comprising a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode,

comprising a step of obtaining the positive electrode material by heat-treating a mixture of a lithium source, a cobalt source, and a phosphoric acid source,

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 2 theta of 13.1 DEG + -0.2 DEG, 14.0 DEG + -0.2 DEG and 18.4 DEG + -0.2 DEG in X-ray diffraction of the radiated light of 5 DEG to 90 DEG,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

9. A positive electrode material characterized in that,

at the wavelength of use

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xFe_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

10. A method for producing a positive electrode material is characterized by producing the following positive electrode material:

at the wavelength of use

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xFe_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2;

the method for producing the positive electrode material includes a step of heat-treating a mixture of a lithium source, an iron source, and a phosphoric acid source.

11. A battery, comprising:

a positive electrode containing a positive electrode material, wherein,

a negative electrode, and

an electrolyte disposed between the positive electrode and the negative electrode;

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 2 theta of 13.1 DEG + -0.2 DEG, 14.0 DEG + -0.2 DEG and 18.4 DEG + -0.2 DEG in X-ray diffraction of the radiated light of 5 DEG to 90 DEG,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xFe_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

12. A method for producing a battery comprising a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode,

comprising a step of obtaining the positive electrode material by heat-treating a mixture of a lithium source, an iron source and a phosphoric acid source,

the positive electrode material is as follows:

at the wavelength of use

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xFe_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

13. An electronic device is characterized by comprising a battery and an electronic circuit,

the battery has:

a positive electrode containing a positive electrode material, wherein,

a negative electrode, and

an electrolyte disposed between the positive electrode and the negative electrode;

the electronic circuit is electrically connected to the positive electrode and the negative electrode,

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 2 theta of 13.1 DEG + -0.2 DEG, 14.0 DEG + -0.2 DEG and 18.4 DEG + -0.2 DEG in X-ray diffraction of the radiated light of 5 DEG to 90 DEG,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

14. An electronic device is characterized by comprising a battery and an electronic circuit,

the battery has:

a positive electrode containing a positive electrode material, wherein,

a negative electrode, and

an electrolyte disposed between the positive electrode and the negative electrode;

the electronic circuit is electrically connected to the positive electrode and the negative electrode,

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 2 theta of 13.1 DEG + -0.2 DEG, 14.0 DEG + -0.2 DEG and 18.4 DEG + -0.2 DEG in X-ray diffraction of the radiated light of 5 DEG to 90 DEG,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xFe_1+xP₂O₇Expressed in the formula, x is more than or equal to-0.2 and less than or equal to 0.2.

Technical Field

The present invention relates to a positive electrode material and a method for producing the same, a battery using the positive electrode material and a method for producing the same, and an electronic device using the battery.

Background

Secondary batteries have been widely used as secondary batteries for mobile phones, portable personal computers, sensor devices, electric vehicles, and the like. Examples of the secondary battery include a nickel-metal hydride battery, a nickel-cadmium battery, and a lithium ion battery. Among these, lithium ion batteries have attracted attention from the viewpoint of high energy density.

In general, a battery has a positive electrode active material that undergoes an oxidation-reduction reaction in a positive electrode, and has a negative electrode active material that undergoes an oxidation-reduction reaction in a negative electrode. In the case of a lithium ion battery, a redox reaction is performed upon intercalation or deintercalation of lithium ions. In the case of a lithium ion battery, a positive electrode active material capable of inserting or extracting lithium ions is provided on a positive electrode (for example, patent document 1). In a lithium ion battery, lithium ions as an oxidation-reduction reaction move between a positive electrode and a negative electrode, and electrons move with the movement of the lithium ions, so that electric current flows. By taking this flowing electricity out of the lithium ion battery, the lithium ion battery exhibits its function.

As a positive electrode material and an energy density thereof which are now put into practical use, there is LiCoO₂(570Wh/kg)、LiFePO₄(530Wh/kg)、LiMn₂O₄(590 Wh/kg). That is, the energy density of the currently put to practical use positive electrode material is in the range of 500Wh/kg to 600 Wh/kg. However, these energy densities are not sufficient for further downsizing of the battery, and therefore development of a novel positive electrode material having an energy density higher than that of these materials is desired.

Disclosure of Invention

The purpose of the present invention is to provide a positive electrode material having a high energy density, a method for producing the same, a battery using the positive electrode material, and a method for producing the battery.

In one embodiment, the positive electrode material is at the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light of (a), and belongs to space group P2₁A monoclinic crystal structure of the formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

In one embodiment, a method for producing a positive electrode material produces the following positive electrode material:

at the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light,

having the property of belonging to space group P2₁A monoclinic crystal structure of the formula Li_2－2xCo₁+_xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2);

the method for producing the positive electrode material includes a step of heat-treating a mixture of a lithium source, a cobalt source, and a phosphoric acid source.

In one embodiment, a battery includes: a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode,

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

In one embodiment, a method for producing a battery includes a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode,

comprising the step of obtaining the positive electrode material by heat-treating a mixture of a lithium source, a cobalt source and a phosphoric acid source,

the positive electrode material is as follows:

at the wavelength of use

Has diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

by the composition formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

In one embodiment, an electronic device includes a battery and an electronic circuit,

the battery has:

a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode;

the electronic circuit is electrically connected to the positive and negative electrodes,

the positive electrode material is as follows:

at the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light,

having the property of belonging to space group P2₁The monoclinic crystal structure of/c,

group ofInto formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

As one aspect, a positive electrode material having a high energy density can be provided.

In addition, as one aspect, a method for producing a positive electrode material having a high energy density can be provided.

In addition, as one aspect, a battery having a high energy density can be provided.

In addition, as one aspect, a method of manufacturing a battery having a high energy density can be provided.

In addition, as one aspect, an electronic device having high energy density can be provided.

Drawings

FIG. 1 shows Li₂CoP₂O₇Schematic representation of the crystal structure of (a).

Fig. 2 is a schematic diagram showing the crystal structure of the disclosed cathode material.

Fig. 3 is a portion of an XRD spectrum of the disclosed positive electrode material.

Fig. 4 is a schematic cross-sectional view showing one example of the disclosed battery.

Fig. 5 is an XRD spectrum of the positive electrode materials of example 1(a) and comparative example 1 (B).

Fig. 6 is a constant current charge and discharge curve of a half cell using the positive electrode materials of example 4 and comparative example 4.

Fig. 7 is a constant current charge and discharge curve of a half cell using the positive electrode material of example 6.

Fig. 8 is a schematic cross-sectional view showing an example of the disclosed electronic apparatus.

Detailed Description

(Positive electrode Material)

One mode of the disclosed positive electrode material consists of Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

One embodiment of the positive electrode material has a monoclinic crystal structure and belongs to space group P2₁/c。

The positive electrode materialOne mode of the material is in the use wavelengthHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

Another mode of the disclosed positive electrode material consists of Li_2－2xFe_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

Another mode of the positive electrode material has a monoclinic crystal structure and belongs to space group P2₁/c。

Another mode of the above positive electrode material is at the use wavelengthHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

To date, various reports have been made on positive electrode materials, one of which is about crystalline Li₂CoP₂O₇Report (Kim, H.et al, Chemistry of Materials 2011, 23(17), 3930-. In this report, Li₂CoP₂O₇Theoretically having an energy density of 1000 Wh/kg. This is an energy density about 2 times that of the conventional positive electrode material. The reason why the large energy density is expected in this way is 2 points below.

Voltages up to 4.9V

Assuming that the capacity density of all lithium ions in the positive electrode material during charge and discharge is as high as 216mAh/g as represented by the following formula (I)

However, the current situation is that only a capacity density of 90mAh/g corresponding to about 40% of the theoretical capacity density can be confirmed.

Therefore, the present inventors assumed that Li was present in the above report₂CoP₂O₇The crystal structure of (ICSD #261899) is problematic. The crystal structure is shown in FIG. 1. In this crystal structure, as shown in fig. 1, lithium atom or cobalt atom 1, lithium atom 2, oxygen atom 3, and phosphorus atom 4 are arranged. Here, lithium atom or cobalt atom 1 indicates that a unit cell in which the atom at the corresponding position is a lithium atom and a unit cell in which the atom at the corresponding position is a cobalt atom are present in a mixture.

In a lithium ion battery, lithium atoms (lithium ions) move during charging or discharging. In the positive electrode, lithium ions are desorbed from or inserted into a positive electrode material (positive electrode active material). Therefore, the crystals of the positive electrode material need to be in the following state in order to function as a positive electrode material (positive electrode active material). It is necessary that the crystal structure of the positive electrode material does not change or can reversibly change even if lithium atoms (lithium ions) that move during charge or discharge are desorbed from or inserted into the crystal of the positive electrode material.

In Li₂CoP₂O₇In the method, a part of lithium atoms is arranged at an important position to maintain Li₂CoP₂O₇In the case of the crystal structure of (3), the lithium atom is used only for maintaining the crystal structure. Therefore, the lithium atoms cannot be used for the exchange between the positive electrode and the negative electrode during charge and discharge, that is, the redox reaction. This is probably a main reason why the theoretical capacity value could not be confirmed in the reported positive electrode material.

Therefore, the present inventors have conducted investigations on Li having different crystal structures₂CoP₂O₇A study was conducted. As a result, Li having a crystal structure shown in FIG. 2 was found₂CoP₂O₇Thus, the present invention has been completed.

In addition, the present inventors have found that Li in which cobalt atoms are replaced with iron atoms in the crystal structure shown in FIG. 2₂FeP₂O₇Can also be used as a positive electrode material.

In the positive electrode material, the number of oxygen atoms to be incorporated into cobalt atoms or iron atoms is preferably 4 to 5.

The number of oxygen atoms coordinated to cobalt atoms or iron atoms can be estimated by estimating the distance between the cobalt atoms and the oxygen atoms in the crystal structureThe distance from the iron atom or the oxygen atom. The distance between the cobalt atom and the oxygen atom or the distance between the iron atom and the oxygen atom can be calculated from the height of the peak (peak intensity) in the X-ray diffraction by simulation. For example, in the crystal structure of the disclosed positive electrode material, the ideal distance of cobalt atoms or iron atoms from oxygen atoms is

Thus, the cobalt atom or iron atom can be counted as the centerOxygen atoms coordinated to cobalt atoms or iron atoms.

In FIG. 2, the polyhedron shown with the lithium or cobalt atom 1 as the center is such that the cobalt atom is centered and located away from

A polyhedron of oxygen atoms of distance (d).

< peak of X-ray diffraction >

In the positive electrode material of the present invention, the positive electrode material is composed of Li_2－2xCo_1+xP₂O₇Positive electrode material expressed by (-0.2 ≦ x ≦ 0.2) and used wavelengthHas diffraction peaks at the following positions in the X-ray diffraction (2 θ ═ 5 ° to 90 °).

2 θ 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 °

FIG. 3 shows a positive electrode material (Li) of the present invention₂CoP₂O₇) The 2 theta is 7.5-20.5 DEG in the X-ray diffraction diagram. As shown in fig. 3, among several peaks, peaks having a strong intensity compared to other peaks appear at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 °. Therefore, having diffraction peaks at 2 θ ═ 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in X-ray diffraction means that the peak is a peak showing extremely high intensity compared with other peaks.

In the positive electrode material of the present invention, the positive electrode material is composed of Li_2－2xFe_1+xP₂O₇Positive electrode material expressed by (-0.2 ≦ x ≦ 0.2) and used wavelengthHas diffraction peaks at the following positions in the X-ray diffraction (2 θ ═ 5 ° to 90 °).

2 θ 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 °

As the lattice constant of the positive electrode material, preferred is

And β -148.

The lattice constant of the positive electrode material can be calculated from the above X-ray diffraction data.

(method for producing Positive electrode Material)

The method for producing the disclosed positive electrode material is not particularly limited and may be appropriately selected depending on the purpose, but the following method for producing a positive electrode material is preferable.

One embodiment of the disclosed method for producing a positive electrode material includes a step of heat-treating a mixture of a lithium source, a cobalt source, and a phosphoric acid source, and further includes other steps such as a mixing step if necessary.

One embodiment of the method for producing a positive electrode material is a method for producing a positive electrode material satisfying the following requirements (1) to (3).

(1) By the composition formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(2) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(3) At the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

Another embodiment of the disclosed method for producing a positive electrode material includes a step of heat-treating a mixture of a lithium source, an iron source, and a phosphoric acid source, and further includes other steps such as a mixing step, if necessary.

Another embodiment of the above method for producing a positive electrode material is a method for producing a positive electrode material satisfying the following requirements (4) to (6).

(4) By the composition formula Li_2－2xFe_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(5) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(6) At the wavelength of use

Has diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

< mixing Process >

The mixing step is not particularly limited as long as it is a step of mixing a lithium source, a cobalt source, and a phosphoric acid source to obtain a mixture thereof, and may be appropriately selected according to the purpose, and for example, it may be performed using a planetary ball mill. When this mixing step is used, Li having a composition formula_2－2xCo_1+xP₂O₇The positive electrode material shown.

The mixing step is not particularly limited as long as it is a step of mixing a lithium source, an iron source, and a phosphoric acid source to obtain a mixture thereof, and may be appropriately selected according to the purpose, and for example, it may be performed using a planetary ball mill. When this mixing step is used, Li having a composition formula_2－2xFe_1+xP₂O₇The positive electrode material shown.

Examples of the lithium source include lithium salts.

The anion constituting the lithium salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include hydroxide ion, carbonate ion, oxalate ion, acetate ion, nitrate anion, sulfate anion, phosphate ion, fluoride ion, chloride ion, bromide ion, iodide ion, and the like.

These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The lithium salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include lithium hydroxide (LiOH) and lithium carbonate (Li)₂CO₃) Lithium nitrate (LiNO)₃) Lithium sulfate (Li)₂SO₄) Lithium perchlorate (LiClO)₄) Lithium hexafluorophosphate (LiPF)₆) Lithium tetrafluoroborate (LiBF)₄) And the like. These may be hydrates or anhydrates. Among these, lithium carbonate and lithium nitrate are preferable because side reactions do not occur.

Examples of the cobalt source include cobalt salts.

The anion constituting the cobalt salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include carbonate ion, oxalate ion, acetate ion, nitrate anion, sulfate anion, phosphate ion, fluoride ion, chloride ion, bromide ion, iodide ion, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The cobalt salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include cobalt oxalate, cobalt nitrate, cobalt sulfate, and cobalt chloride. These may be hydrates or anhydrates.

Examples of the iron source include iron salts.

The anion constituting the iron salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include an oxygen ion, a carbonate ion, an oxalate ion, an acetate ion, a nitrate anion, a sulfate anion, a phosphate ion, a fluoride ion, a chloride ion, a bromide ion, an iodide ion, and the like.

These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The iron salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include iron oxide, iron (II) oxalate, iron (II) nitrate, iron (II) sulfate, and iron (II) chloride. These may be hydrates or anhydrates.

Examples of the phosphoric acid source include phosphoric acid and a phosphate.

The cation constituting the phosphate is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include ammonium ions and the like.

Examples of the phosphate include ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

In addition, instead of the lithium source and the phosphoric acid source, a compound that is a lithium source and a phosphoric acid source, such as lithium phosphate, dilithium hydrogen phosphate, or lithium dihydrogen phosphate, may be used.

The ratio of the lithium source, the cobalt source and the phosphoric acid source in the mixing is not particularly limited, and may be appropriately selected depending on the purpose, and examples thereof include Li: co: p is 1.6-2.4: 0.8-1.2: 2.0 (element ratio), etc.

The ratio of the lithium source, the iron source, and the phosphoric acid source in the mixing is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include Li: fe: p is 1.6-2.4: 0.8-1.2: 2.0 (element ratio), etc.

< Heat treatment Process >

The heat treatment step is not particularly limited as long as the mixture is subjected to heat treatment, and may be appropriately selected according to the purpose.

The number of times of performing the heat treatment step is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 2 times.

The first heat treatment step is performed to remove carbon dioxide and ammonia generated from a lithium source, a phosphoric acid source, a cobalt source, an iron source, and the like.

The temperature of the first heat treatment is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 500 to 720 ℃.

The time for the first heat treatment is not particularly limited, and may be appropriately selected depending on the purpose, and is preferably 1 to 24 hours, more preferably 2 to 18 hours, and particularly preferably 3 to 15 hours.

The second heat treatment is performed to bring the mixture to a desired crystal structure. When the heat treatment was performed only 1 time, the heat treatment conditions used in the second heat treatment were as follows.

The temperature of the second heat treatment is not particularly limited and may be appropriately selected according to the purpose, and is preferably 420 to 520 ℃, and more preferably 450 to 510 ℃. If the temperature of the heat treatment is less than 420 c or exceeds 520 c, a desired crystal structure may not be obtained in some cases.

The time of the heat treatment is not particularly limited, and may be appropriately selected according to the purpose, and is preferably 1 to 24 hours.

The heat treatment is preferably performed in an inert atmosphere. The inert atmosphere includes, for example, an argon atmosphere.

(Battery)

The disclosed battery has: a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode, and further has other members as necessary.

One embodiment of the battery has a positive electrode containing a positive electrode material satisfying the following (1) to (3).

(1) By the composition formula Li_2－2xCo₁+_xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(2) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(3) At the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

The above battery uses the disclosed positive electrode material having a high energy density. Therefore, the disclosed battery becomes a battery having a high energy density.

Another embodiment of the above battery has a positive electrode containing the following positive electrode materials (4) to (6).

(4) By the composition formula Li₂－_2xFe₁+_xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(5) Having the property of belonging to space group P2₁C ofMonoclinic crystal structure.

(6) At the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

The battery includes at least a positive electrode, and further includes a negative electrode, an electrolyte, a separator, a positive electrode case, a negative electrode case, and other members as necessary.

< positive pole >

The positive electrode includes at least the disclosed positive electrode material, and further includes other members such as a positive electrode current collector, if necessary.

In the positive electrode, the positive electrode material functions as a so-called positive electrode active material.

The content of the positive electrode material in the positive electrode is not particularly limited, and may be appropriately selected according to the purpose.

In the positive electrode, the above-mentioned positive electrode material may be mixed together with a conductive material and a binder material to form a positive electrode layer.

The conductive material is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a carbon-based conductive material. Examples of the carbon-based conductive material include acetylene black and carbon black.

The binder is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), and carboxymethylcellulose (CMC).

The material, size, and structure of the positive electrode are not particularly limited, and may be appropriately selected according to the purpose.

The shape of the positive electrode is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a rod shape and a disk shape.

Positive electrode current collector

The shape, size, and structure of the positive electrode current collector are not particularly limited, and may be appropriately selected according to the purpose.

The material of the positive electrode current collector is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include stainless steel, aluminum, copper, and nickel.

The positive electrode current collector is used to make the positive electrode layer and the positive electrode case as a terminal conduct well.

Negative electrode

The negative electrode has at least a negative electrode active material, and further has other members such as a negative electrode current collector as necessary.

The size and structure of the negative electrode are not particularly limited and may be appropriately selected according to the purpose.

The shape of the negative electrode is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a rod shape and a disk shape.

Negative electrode active material-

The negative electrode active material is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include compounds having an alkali metal element.

Examples of the compound having an alkali metal element include a simple metal, an alloy, a metal oxide, and a metal nitride.

Examples of the alkali metal element include lithium.

Examples of the simple metal include lithium.

Examples of the alloy include alloys containing lithium. Examples of the alloy having lithium include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, a lithium silicon alloy, and the like.

Examples of the metal oxide include a metal oxide containing lithium. Examples of the metal oxide having lithium include lithium titanium oxide and the like.

Examples of the metal nitride include a metal nitride containing lithium. Examples of the lithium-containing metal nitride include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride.

The content of the negative electrode active material in the negative electrode is not particularly limited and may be appropriately selected according to the purpose.

In the negative electrode, a negative electrode active material may be mixed together with a conductive material and a binder material to form a negative electrode layer.

The conductive material is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a carbon-based conductive material. Examples of the carbon-based conductive material include acetylene black and carbon black.

The binder is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-butadiene rubber (EPBR), styrene-butadiene rubber (SBR), and carboxymethylcellulose (CMC).

Negative electrode current collector

The shape, size, and structure of the negative electrode current collector are not particularly limited, and may be appropriately selected according to the purpose.

The material of the negative electrode current collector is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include stainless steel, aluminum, copper, and nickel.

The negative electrode current collector serves to make the negative electrode layer well conductive to the negative electrode case as a terminal.

Electrolyte

The electrolyte is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a nonaqueous electrolyte solution and a solid electrolyte.

Non-aqueous electrolyte

Examples of the nonaqueous electrolytic solution include a nonaqueous electrolytic solution containing a lithium salt and an organic solvent.

-lithium salt- -

The lithium salt is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis (pentafluoroethanesulfonyl) imide, lithium bis (trifluoromethanesulfonyl) imide, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The concentration of the lithium salt is not particularly limited and may be appropriately selected depending on the purpose, and is preferably 0.5 to 3mol/L in the organic solvent from the viewpoint of ionic conductivity.

-organic solvent- -

The organic solvent is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the nonaqueous electrolytic solution as the organic solvent is not particularly limited and may be appropriately selected according to the purpose, and is preferably 75 to 95% by mass, and more preferably 80 to 90% by mass.

If the content of the organic solvent is less than 75 mass%, the viscosity of the nonaqueous electrolytic solution increases and the wettability to the electrode decreases, which may increase the internal resistance of the battery, and if it exceeds 95 mass%, the ionic conductivity decreases and the output of the battery may decrease. On the other hand, if the content of the organic solvent is within the more preferable range described above, it is advantageous in that high ionic conductivity can be maintained, and wettability to the electrode can be maintained by suppressing the viscosity of the nonaqueous electrolytic solution.

Solid electrolyte

The solid electrolyte is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include an inorganic solid electrolyte and an intrinsic polymer electrolyte.

Examples of the inorganic solid electrolyte include LISICON materials and perovskite materials.

Examples of the intrinsic polymer electrolyte include polymers having an ethylene oxide bond.

The content of the electrolyte in the battery is not particularly limited, and may be appropriately selected according to the purpose.

Isolating piece

The material of the separator is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include paper, cellophane, polyolefin nonwoven fabric, polyamide nonwoven fabric, and glass fiber nonwoven fabric. Examples of the paper include kraft paper, vinylon mixed paper, synthetic pulp mixed paper, and the like.

The shape of the separator is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include a sheet shape.

The separator may have a single-layer structure or a laminated structure.

The size of the spacer is not particularly limited, and may be appropriately selected according to the purpose.

Positive electrode shell

The material of the positive electrode case is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include copper, stainless steel, and a metal obtained by plating stainless steel or iron with nickel or the like.

The shape of the positive electrode case is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a shallow disc shape, a bottomed cylindrical shape, a bottomed prismatic shape, and the like, the periphery of which is warped upward.

The positive electrode case may have a single-layer structure or a stacked structure. Examples of the laminated structure include a three-layer structure of nickel, stainless steel, and copper.

The size of the positive electrode case is not particularly limited, and may be appropriately selected according to the purpose.

Negative electrode shell

The material of the negative electrode case is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include copper, stainless steel, and a metal obtained by plating stainless steel or iron with nickel or the like.

The shape of the negative electrode case is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a shallow disc shape, a bottomed cylindrical shape, a bottomed prismatic shape, and the like, the periphery of which is warped upward.

The structure of the negative electrode case may be a single-layer structure or a laminated structure. Examples of the laminated structure include a three-layer structure of nickel, stainless steel, and copper.

The size of the negative electrode case is not particularly limited and may be appropriately selected according to the purpose.

The shape of the battery is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include a coin shape, a cylindrical shape, a rectangular shape, and a sheet shape.

An example of the disclosed lithium ion secondary battery will be described with reference to the drawings. Fig. 4 is a schematic sectional view showing a lithium-ion secondary battery as an example of the disclosed battery.

The lithium ion secondary battery shown in fig. 4 is a coin-type lithium ion secondary battery. The coin-type lithium ion secondary battery includes a positive electrode 10 including a positive electrode current collector 11 and a positive electrode layer 12, a negative electrode 20 including a negative electrode current collector 21 and a negative electrode layer 22, and an electrolyte layer 30 interposed between the positive electrode 10 and the negative electrode 20. In the lithium ion secondary battery of fig. 4, the positive electrode current collector 11 and the negative electrode current collector 21 are fixed to the positive electrode case 41 and the negative electrode case 42, respectively, via the current collectors 43. The space between the positive electrode case 41 and the negative electrode case 42 is sealed with a packaging material 44 made of polypropylene, for example. The current collector 43 is used to fill the gap between the positive electrode current collector 11 and the positive electrode case 41 and between the negative electrode current collector 21 and the negative electrode case 42 and to achieve conduction.

Here, positive electrode layer 12 is made of a disclosed positive electrode material.

(method of manufacturing Battery)

The disclosed method for manufacturing a battery is a method for obtaining the above battery.

Disclosed is a method for producing a battery having a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode.

One embodiment of the above-described method for producing a battery includes a step of obtaining a positive electrode material by heat-treating a mixture of a lithium source, a cobalt source, and a phosphoric acid source, and further includes other steps such as a step of assembling a positive electrode, a negative electrode, and the like into a desired structure as necessary.

In one embodiment of the method for manufacturing a battery, the positive electrode material satisfies the following (1) to (3).

(1) By the composition formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(2) Having the property of belonging to space group P2₁C is aA crystal structure of an orthorhombic crystal.

(3) At the wavelength of use

Has diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

The disclosed batteries use the disclosed positive electrode materials having high energy density. Also, the disclosed battery becomes a battery having a high energy density. Therefore, the disclosed method for manufacturing a battery is a method for obtaining a battery having a high energy density.

Another embodiment of the above battery production method includes a step of obtaining a positive electrode material by heat-treating a mixture of a lithium source, an iron source, and a phosphoric acid source, and further includes other steps such as a step of assembling a positive electrode, a negative electrode, and the like into a desired structure as necessary.

In another embodiment of the method for manufacturing a battery, the positive electrode material satisfies the following (4) to (6).

(4) By the composition formula Li_2－2xFe_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(5) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(6) At the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

(electronic apparatus)

The disclosed electronic device includes a battery and an electronic circuit, and further includes other members as necessary.

< Battery >

The battery has a positive electrode containing a positive electrode material, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode, and further has other members as necessary.

The negative electrode, the electrolyte, and other members are not particularly limited and may be appropriately selected according to the purpose, and the above-described negative electrode, electrolyte, and other members are preferably used.

One embodiment of the battery has a positive electrode containing a positive electrode material satisfying the following (1) to (3).

(1) By the composition formula Li_2－2xCo_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(2) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(3) At the wavelength of useHas diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

The above battery uses the disclosed positive electrode material having a high energy density. Therefore, the disclosed battery becomes a battery having a high energy density. Also, the disclosed electronic device is provided with a battery having a high energy density.

Another embodiment of the battery has a positive electrode containing a positive electrode material satisfying the following (4) to (6).

(4) By the composition formula Li_2－2xFe_1+xP₂O₇X is more than or equal to (-0.2) and less than or equal to 0.2).

(5) Having the property of belonging to space group P2₁Monoclinic crystal structure of/c.

(6) At the wavelength of use

Has diffraction peaks at 13.1 ° ± 0.2 °, 14.0 ° ± 0.2 ° and 18.4 ° ± 0.2 ° in the X-ray diffraction (2 θ ═ 5 ° to 90 °) of the radiation light.

The shape and size of the battery are not particularly limited and may be appropriately selected according to the purpose.

The number of batteries provided in the electronic device is not particularly limited, and may be appropriately selected according to the purpose, and for example, the electronic device may be incorporated as a battery pack in which a plurality of batteries are assembled.

< electronic Circuit >

The electronic circuit is electrically connected to the positive and negative electrodes.

The material, shape, and size of the electronic circuit are not particularly limited, and may be appropriately selected according to the purpose.

The electronic circuit includes, for example, a cpu (central Processing unit), a peripheral logic unit, an interface unit, a memory unit, and the like, and can control the entire electronic apparatus.

The electronic device is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include the following electronic devices. Examples of the portable information terminal include a notebook Personal computer, a tablet Personal computer, a mobile phone (e.g., a smartphone), a Personal Digital Assistant (PDA), an image pickup apparatus (e.g., a Digital camera, a Digital video camera, etc.), an audio device (e.g., a portable audio player), a game device, a cordless extension phone, an electronic book, an electronic dictionary, a radio, an earphone, a navigation system, a memory card, a pacemaker, a hearing aid, a lighting device, a toy, a medical device, and a robot.

An example of the disclosed electronic device will be described with reference to the drawings. Fig. 8 is a schematic cross-sectional view showing an example of the disclosed electronic apparatus. The electronic device 001 includes an electronic circuit 002 and a battery 003 of an electronic device main body. The battery 003 is electrically connected to the electronic circuit 002 via the positive electrode terminal 003a and the negative electrode terminal 003 b. The electronic device 001 has a structure in which the battery pack 003 can be freely attached and detached by a user, for example. The configuration of the electronic device 001 is not limited to this, and the battery pack 003 may be incorporated in the electronic device 001 so that the user cannot remove the battery pack 003 from the electronic device 001.

The battery pack 003 includes a battery pack 004 and a charge/discharge circuit 005. The assembled battery 004 is configured by connecting a plurality of secondary batteries 004a in series and/or in parallel. The plurality of cells 004a are connected, for example, in n-parallel m-series (n and m are positive integers). As the battery 004a, the above-described battery or the battery according to the modified example thereof can be used. Instead of the assembled battery 004, a configuration may be adopted in which only one secondary battery 004a is provided.

The electronic circuit 002 includes, for example, a cpu (central Processing unit), a peripheral logic unit, an interface unit, and a memory unit, and controls the entire electronic device 001.

During charging of the battery 003, the positive electrode terminal 003a and the negative electrode terminal 003b of the battery 003 are connected to a positive electrode terminal and a negative electrode terminal of a charger (not shown), respectively. On the other hand, during discharge of the battery pack 003 (during use of the electronic device 001), the positive electrode terminal 003a and the negative electrode terminal 003b of the battery pack 003 are connected to the positive electrode terminal and the negative electrode terminal of the electronic circuit 002, respectively.

At the time of charging, the charge and discharge circuit 005 controls charging of the battery pack 004. On the other hand, during discharging (i.e., during use of the electronic device 001), the charge/discharge circuit 005 controls discharge to the electronic device 001.