JP3532139B2 - Method for producing nickel-containing oxide electrode material and battery using the electrode material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a nickel-containing oxide electrode material and a battery using the same, and more particularly to a technique for providing a battery having a large discharge capacity.

[0002]

2. Description of the Related Art Nickel-containing oxides are widely used as cathode materials for aqueous batteries such as nickel cadmium batteries and non-aqueous batteries such as lithium batteries. Examples of the synthesis method include a method in which a divalent nickel compound such as nickel hydroxide is chemically or electrochemically oxidized to obtain a compound containing nickel trivalent which functions as a positive electrode material.

However, these substances are nickel 2
Since the number of electrons that can be used at the time of reduction to a valency is small, there is a problem that the discharge capacity of a battery using these substances as a cathode material is small. Examples of the compound containing tetravalent nickel include a layered compound Li _x NiO ₂ (0 ≦ X <1). However, since there are few ion storage positions available at the time of reduction, these materials are used as a cathode material. There is a problem that the capacity of the battery to be used is small.

In addition, a compound containing tetravalent nickel, which is a compound containing water between layers, is obtained by oxidizing a divalent or trivalent nickel compound with bromine or hypochlorite, etc. Although there is a compound called γ-NiOOH, it has low crystallinity, so that ion storage efficiency is low and there is a problem that the capacity of a battery using this substance as a positive electrode material is small.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned current problems and provides a method for producing a nickel-containing oxide electrode material having a large discharge capacity and a battery using the nickel-containing oxide electrode material. Is to do.

[0006]

Means for Solving the Problems To achieve the above object, in the method for producing a nickel-containing oxide according to the present invention, a layered compound Li _X NiO ₂ (0 ≦ X <1) is used as a starting material.
And an aqueous alkaline solution of hydroxide dissolved in water.
The method is characterized by having a step of inserting water molecules between layers of the layered compound by treating the layered compound .

[0007] In the battery according to the present invention further, claim 1 or
Others in the production method of the nickel-containing oxide electrode material wherein
Having a positive electrode containing the produced nickel-containing oxide electrode material as a positive electrode active material, lithium, sodium, potassium,
Magnesium, calcium, strontium, aluminum, copper, a negative electrode containing a substance containing any of silver or a substance capable of reversibly inserting / desorbing or occluding / desorbing this element, wherein the ions of the element are the positive electrode and characterized in that it comprises a material moving may perform for the negative electrode and the electrochemical reaction as the electrolyte material.

Further, in the second battery according to the present invention, a method for producing a nickel-containing oxide electrode material according to claim 1 or 2.
Having a positive electrode containing a nickel-containing oxide electrode material produced by law as a positive electrode active material, protons and having a substance moving may perform for the positive electrode and the electrochemical reaction as the electrolyte material.

The present invention will be described in more detail. The inventor has made extensive searches for a nickel-containing oxide electrode material and a method for manufacturing the same, and as a result, a battery using the nickel-containing oxide electrode material and a battery using the nickel-containing oxide electrode material manufactured by the method described above, It has been confirmed that a nickel-containing oxide electrode material having a large discharge capacity and a battery containing the nickel-containing oxide electrode material can be manufactured and realized, and the present invention has been completed based on the recognition.

The reason is considered as follows. That is, the nickel-containing oxide electrode material of the present invention,
It contains water molecules between the layers of the layered compound Li _x NiO ₂ ,
Since the layers are wide open, there are many ion storage positions available for reduction. Moreover, Li _X containing nickel tetravalent
Since NiO ₂ (0 ≦ X <1) is used as a base,
Discharge exceeding one electron is possible before the valence of nickel reaches bivalence.

The range of the above X is 0 ≦ X <1. X =
In the case of 1, since there is no reducing ability, it is not possible to obtain a large capacity which is an effect of the present invention. Further, as X is closer to 0, the nickel-containing oxide after inserting water molecules between layers contains more tetravalent nickel, and as a result, a larger discharge capacity is often obtained. Therefore, preferably 0 ≦ X ≦
0.5, more preferably 0 ≦ X ≦ 0.2.

According to the method for producing a nickel-containing oxide electrode material according to the present invention, water molecules are inserted into Li _x NiO ₂ .

The amount of water contained between the layers varies greatly depending on the method of inserting water molecules between the layers of Li _x NiO ₂ . When no water is contained, the interlayer is narrow, the number of ion storage positions available for reduction is small, and the discharge capacity is small. When the number of water molecules is very large, the portion not involved in the discharge increases, and the weight energy density decreases.

As a method for inserting water molecules between the layers of the layered compound Li _x NiO ₂ , an aqueous alkaline solution obtained by dissolving a hydroxide containing alkali metal ions, alkaline earth metal ions, ammonium ions and the like as cations in water is used. so,
A method of treating Li _x NiO ₂ is given. in this case,
The hydroxide ions are oxidized by Li _x NiO ₂ to generate oxygen, and at the same time, Li _x NiO ₂ is reduced. At this time, the cations and water contained in the solution are converted to Li _x N 2
It is taken in between the layers of iO ₂ .

Further, even if Li _x NiO ₂ is reduced by an electrochemical method in an aqueous solution containing the cations, the cations and water contained in the solution become Li _x N 2
It is taken in between the layers of iO ₂ . Water molecules can also be inserted between Li _x NiO ₂ layers by high-pressure reaction and hydrothermal synthesis. The cation species taken in between the layers can be exchanged with arbitrary ions by ion exchange, and there is no particular limitation.

Li _X NiO ₂ can be synthesized by a conventionally known method such as acid treatment of LiNiO ₂ or electrochemical lithium elimination.

The sample obtained by the method for producing a nickel-containing hydroxide according to the present invention comprises Li _x Ni obtained at a high temperature.
Since a nickel-containing oxide containing nickel tetravalent and containing water molecules between layers can be obtained while maintaining the high crystallinity of O ₂ , the efficiency of ion storage is higher than that of a sample with poor crystallinity, and This has the advantage that a large capacity can be realized as the positive electrode material of (1).

The amount of oxygen with respect to nickel may slightly increase or decrease depending on the synthesis conditions when water molecules are inserted between the layers of Li _x NiO ₂ (0 ≦ X <1). Although the details of this mechanism are not clear, if the amount of oxygen with respect to nickel is close to 2, the layer structure is maintained and there is no influence on the characteristics.

To form a battery positive electrode using the nickel-containing oxide electrode material according to the present invention as a positive electrode active material, a mixture of the nickel-containing oxide electrode material and a binder powder such as polytetrafluoroethylene is mixed with stainless steel. Or a mixture of conductive powder such as acetylene black to impart conductivity to the mixture powder, and further require a binder powder such as polytetrafluoroethylene. Conventionally known methods such as adding this mixture to a metal container, or pressing and molding the mixture on a support such as stainless steel, or dispersing in a solvent such as an organic solvent to form a slurry and applying the slurry on a metal substrate. There is no particular limitation.

Further, the battery according to the present invention has a positive electrode containing the nickel-containing oxide electrode material as a positive electrode active material. When the negative electrode contains a substance containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, silver or a substance capable of reversibly inserting / desorbing or occluding / desorbing the element, By having, as an electrolyte material, a substance capable of performing an electrochemical reaction between the element ions and the positive electrode and the negative electrode, a battery in which the element ions move between the positive electrode and the negative electrode is obtained. For example, as the substance containing lithium, conventionally known materials such as lithium metal, lithium-aluminum alloy, lithium-carbon compound, and lithium-containing nitride can be used.

When a substance capable of performing proton transfer is contained as an electrolyte substance, an acidic aqueous solution, an alkaline aqueous solution, a sodium chloride aqueous solution, or the like can be used as the electrolyte. In this case, a conventionally known negative electrode for an aqueous battery can be used as the negative electrode. For example, a hydrogen storage alloy, iron, copper, zinc, cadmium, aluminum, magnesium and the like can be mentioned, and there is no particular limitation.

The battery can be used as a secondary battery by repeatedly discharging and charging the battery.

As for other elements such as an electrolyte, a separator, and a structural material such as a battery case, various conventionally known materials can be used, and there is no particular limitation.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

[0025]

Embodiment 1 In Embodiment 1, the composition formula Li _0.1 K _0.2 NiO
_The nickel-containing oxide provided by _1.9 · 0.7 H ₂ O is
It was manufactured as follows. First, lithium nitrate and nickel hydroxide are uniformly mixed at a molar ratio of Li: Ni = 2: 1, and the mixture is subjected to a solid-phase reaction in the air at 700 ° C. for 10 hours. LiNiO ₂ was obtained by removing excess alkali by washing with water and drying. When this LiNiO ₂ is analyzed by X-ray diffraction analysis, it can be indexed by a hexagonal crystal (space group R-3m), and the lattice constants are a = 2.875 (Å) and c = 14.19 (Å).
And the distance between the layers was found to be about 4.7 (Å). Next, this LiNiO ₂ was mixed with a 1.2 N sulfuric acid solution at a ratio of H ⁺ / Ni = 4, stirred and reacted for 3 hours, washed with water and dried to obtain Li _0.1 NiO ₂ .
The Li _0.1 NiO ₂ is further mixed with a 0.3 N potassium hydroxide solution at a ratio of K ⁺ /Ni=0.3, stirred and reacted for 3 hours, washed with water and dried to obtain Li _0.1 K.
_0.2 NiO _1.9 · 0.7 H ₂ O was obtained. This sample is designated as a.

FIG. 1 shows an X-ray diffraction pattern of the sample a. This X
When the line diffraction diagram is analyzed, it can be indexed by a monoclinic (space group C2 / m), and the lattice constant is a = 4.902
(Å), c = 2.829 (Å), c = 7.227 (Å),
β = 103.03 (°), and the distance between the layers is 7.04
(Å) was found.

Next, a battery containing this sample a as a positive electrode active material was produced. FIG. 2 is a sectional view of the battery, and FIG.
Among them, 1 is a sealing plate, 2 is a gasket, 3 is a positive electrode case, 4
Denotes a negative electrode, 5 denotes a separator, and 6 denotes a positive electrode mixture pellet. First, the sample a was vacuum-dried, mixed with a conductive agent (acetylene black) and a binder (polytetrafluoroethylene), and then roll-molded to obtain a positive electrode mixture pellet 6. Next, a negative electrode 4 made of metallic lithium and placed under pressure on a sealing plate 1 made of stainless steel is inserted into a concave portion of a gasket 2 made of polypropylene, and a microporous separator 5 made of polypropylene and a positive electrode mixture are placed on the negative electrode 4. The pellets 6 are arranged in this order, and an appropriate amount of a 1 N solution of LiPF ₆ dissolved in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate as an electrolytic solution is injected and impregnated. Then, the stainless steel positive electrode case 3 is covered. By caulking, a coin-type battery having a thickness of 2 mm and a diameter of 23 mm was produced. The production of the battery was performed in a dry box under an argon atmosphere.

A battery containing the thus prepared sample a as a positive electrode active material was tested in a dry box under an argon atmosphere. When discharged to 2.0 V at a current density of 0.5 mA / cm ² at 25 ° C., a capacity of 250 mAh / g per positive electrode weight was obtained. It has an advantage that it can be used as a battery having a large discharge capacity and a high energy density. It was also found that repeated charging and discharging were possible.

[0029]

Example 2 Example 2 was the same as Example 1 except that the composite oxide having the compositional formula of Na _0.3 NiO _2.0 · 0.5 H ₂ O obtained by the following manufacturing method was used as the positive electrode active material. A battery was manufactured in the same manner.

First, lithium nitrate and nickel hydroxide are
Mix uniformly so that Li: Ni = 2: 1 ratio
Then, this is subjected to a solid phase reaction in air at 700 ° C. for 10 hours.
And wash the resulting powder with water to remove excess alkali
LiNiO_TwoGot. This L
iNiO_TwoIs analyzed by X-ray diffraction analysis.
Group R-3m), and the lattice constant is a
= 2.875 (Å), c = 14.19 (Å), and the layer
The distance between them was found to be about 4.7 (Å). next
This LiNiO_TwoAnd H⁺/ Ni = 4 at 1.2
Mixed with sulfuric acid solution, stirred and reacted for 3 hours, washed with water, dried
Li_0.1NiO_TwoGot. Furthermore, this L
i_0.1NiO_TwoWith Na⁺/Ni=0.3 at the rate of 0.3
Mix with the specified sodium hydroxide solution and stir for 3 hours.
And washed with water and dried to obtain Na. _0.3NiO_2.0・
0.5H_TwoO was obtained. This sample is designated as b.

When the X-ray diffraction pattern of sample b is analyzed, it can be indexed by monoclinic (space group C2 / m), and the lattice constants are a = 4.903 (Å) and c = 2.832 ( Å), c
= 7.093 (Å), β = 102.77 (°),
The distance between the layers was found to be 6.92 (Å).

A battery containing the thus prepared sample b as a positive electrode active material was tested in a dry box under an argon atmosphere. Upon discharging to 2.0 V at a current density of 0.5 mA / cm ² at 25 ° C., a capacity of 260 mAh / g per positive electrode weight was obtained. It has an advantage that it can be used as a battery having a large discharge capacity and a high energy density. It was also found that repeated charging and discharging were possible.

[0033]

Example 3 In Example 3, the sample b manufactured in Example 2 was used.
An aqueous battery was prepared by adding a 20% by weight conductive agent to a positive electrode, using a 3 mol / liter aqueous solution of sodium chloride dissolved as an electrolytic solution, and using a zinc plate as a negative electrode. When discharged to 0.7 V at a current density of 0.5 mA / cm ² at 25 ° C., 300 mA per positive electrode weight was discharged.
A capacity of h / g was obtained. It has an advantage that it can be used as a battery having a large discharge capacity and a high energy density.
It was also found that repeated charging and discharging were possible.

In Examples 1 to 3, specific examples of a method for producing a nickel-containing oxide and specific examples of a battery using the same were shown. However, in general, a layered compound Li _x NiO ₂ (0 ≦ X <
1) A method for producing a nickel-containing oxide produced by interposing water molecules between layers, comprising a positive electrode containing the nickel-containing oxide produced by the method for producing a nickel-containing oxide as a positive electrode active material. And a negative electrode containing a substance containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, silver or a substance capable of reversibly inserting / desorbing or occluding / desorbing this element; and A substance capable of performing an electrochemical reaction between the ions of the element and the positive electrode and the negative electrode as an electrolyte substance, or a substance capable of performing proton migration for performing an electrochemical reaction with the positive electrode is referred to as an electrolyte substance. It is needless to say that the same effect can be obtained in the case of a battery having:

[0035]

Comparative Example 1 In Comparative Example 1, a lithium battery was fabricated in the same manner as in Example 1, except that the sample c of the positive electrode active material obtained by the following manufacturing method was used. First, lithium nitrate and nickel hydroxide are uniformly mixed at a molar ratio of Li: Ni = 2: 1, and this is mixed at 700 ° C. for 10 hours.
A solid phase reaction is performed in the air, and the obtained powder is washed with water to remove excess alkali, and dried to obtain LiNiO 2.
Got _two . When this LiNiO ₂ is analyzed by X-ray diffraction analysis, it can be indexed by a hexagonal crystal (space group R-3m), and the lattice constants are a = 2.875 (Å) and c = 14.19.
(Å), and the distance between the layers was found to be about 4.7 (Å). This sample is referred to as c.

A battery containing the thus prepared sample c as a positive electrode active material was tested in a dry box under an argon atmosphere. After charging to 4.3 V at a current density of 0.5 mA / cm ² at 25 ° C. and discharging to 2.0 V, a capacity of 200 mAh / g per positive electrode weight was obtained. Compared with this battery, the battery having the positive electrode active material manufactured in the example of the present invention has a large discharge capacity.

[0037]

Comparative Example 2 In Comparative Example 2, an aqueous solution type battery was produced in the same manner as in Example 3 except that the sample c of the positive electrode active material produced in Comparative Example 1 was used. 0.5 mA / cm at 25 ° C.
When the battery was discharged to 0.7 V at a current density of ² , a capacity of 220 mAh / g per positive electrode weight was obtained. Compared with this battery, the battery having the positive electrode active material manufactured in the example of the present invention has a large discharge capacity.

[0038]

Comparative Example 3 In Comparative Example 3, a lithium battery was fabricated in the same manner as in Example 1, except that the sample c of the positive electrode active material obtained by the following manufacturing method was used. First, bromine is dissolved in a 2N potassium hydroxide solution so as to have a molar ratio of K: Br = 2: 1, and a solution obtained by dissolving nickel nitrate in water at a rate of 2 mol / l is slowly poured thereinto. N
i: K: Br = 4: 10: 5. The obtained precipitate was washed with water and dried to obtain K _0.15 NiO _1.8 ·
It was obtained 0.8H ₂ O. This sample is referred to as d. This sample showed an X-ray diffraction pattern similar to that in FIG. 1, but the diffraction intensity of the maximum intensity peak observed at around 13 degrees was very weak at 300 (cps), and the crystallinity was very low as compared with sample a. I found out.

The battery containing the thus prepared sample d as a positive electrode active material was tested in a dry box under an argon atmosphere. When discharged to 2.0 V at a current density of 0.5 mA / cm ² at 25 ° C., a capacity of 160 mAh / g per positive electrode weight was obtained. Compared with this battery, the battery having the positive electrode active material manufactured in the example of the present invention has a large discharge capacity.

[0040]

As described above, according to the present invention,
A battery having a large discharge capacity can be realized, and has an advantage that it can be used in various fields including a power supply for various electronic devices.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of a sample a in an example of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration example of a coin-type battery according to an embodiment of the present invention.

[Explanation of symbols]

1 sealing plate 2 Gasket 3 Positive case 4 Negative electrode 5 Separator 6 Positive electrode mixture pellet

Continuation of the front page (56) References JP 2001-250548 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/00-4/62 H01M 10/00-10 / 40

Claims (4)

(57) [Claims] 1. The layered compound Li _X NiO ₂ (0 ≦ X <
1) Starting material, alkali with hydroxide dissolved in water
Treating the layered compound with a neutral aqueous solution
A method for producing a nickel-containing oxide electrode material, comprising a step of inserting a water molecule between layers of a crystalline compound . 2. The method according to claim 1, wherein the hydroxide is an alkali metal ion.
Or alkaline earth metal ion or ammonium ion
Is a hydroxide containing any of
The nickel-containing oxide electrode material according to claim 1, wherein
Manufacturing method. 3. Nickel-containing acid according to claim 1 or 2.
Having a positive electrode containing a nickel-containing oxide electrode material produced by the method for producing a nitride electrode material as a positive electrode active material, lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, a substance containing any of silver or An electrolyte material having a negative electrode containing a substance capable of reversibly inserting / desorbing or occluding / desorbing this element, wherein a substance capable of transferring ions of the element for performing an electrochemical reaction with the positive electrode and the negative electrode is used as an electrolyte substance. A battery comprising: 4. Nickel-containing acid according to claim 1 or 2.
Having a positive electrode containing a nickel-containing oxide electrode material produced by the method for producing a nitride electrode material as a positive electrode active material, and having, as an electrolyte material, a substance capable of performing proton transfer for performing an electrochemical reaction with the positive electrode. Features battery.