JP2005332691A - Layered nickel oxide electrode material and its manufacturing method, and battery using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layered oxide electrode material having a large discharge capacity, its manufacturing method, and a battery using the layered oxide electrode material. <P>SOLUTION: This is a layered nickel oxide as expressed by a composition formula A<SB>x</SB>Ni<SB>1-z</SB>M<SB>z</SB>O<SB>2</SB>and has a layered Li<SB>2</SB>MnO<SB>2</SB>type structure. In the formula, A expresses an element and a group to become anion, and when the anion valence of A is set y, xy<1 is satisfied. M expresses a transition series element and one kind or more of elements selected from 2A group, 3A group, 2B group, and 3B group, and 0≤z≤0.5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Nickel-containing oxides are widely used as electrode materials for aqueous solution batteries such as nickel cadmium batteries and non-aqueous battery batteries such as lithium batteries. As a synthesis method, a divalent nickel compound such as nickel hydroxide is chemically or electrochemically oxidized, and a compound containing trivalent nickel that functions as a positive electrode material, such as β-type nickel oxyhydroxide, is used. The method of obtaining is mentioned.

However, since these materials have a small number of electrons that can be used for the reduction to nickel divalent, there is a problem that the discharge capacity of a battery using these materials as a positive electrode material is small. Further, examples of the compound containing nickel tetravalent include a layered compound Li _x NiO ₂ (0 ≦ x <1) and the like. However, since there are few ion storage positions available at the time of reduction, these substances are used as a positive electrode material. There is a problem that the capacity of the battery to be used is small (Japanese Patent No. 3289256).

Although there are few compounds that have a transition metal valence of 4 and have a layered structure and realize ion storage exceeding 1 per transition metal, one of them is layered Li ₂ MnO ₂ type which is a kind of manganese oxide Which can contain two ions per transition metal (manganese). However, as a general tendency of manganese oxide electrodes, it is known that lattice expansion and contraction due to manganese yarn teller distortion is large, and the cycle characteristics of a battery using layered Li ₂ MnO ₂ as an electrode material is not good. Moreover, the nickel oxide corresponding to this was not known.
Japanese Patent No. 3289256 JP 2001-332259 A

  An object of the present invention is to provide a layered nickel oxide electrode material having a large discharge capacity, a method for producing the same, and a battery using the same.

To achieve the above object, layered nickel oxide electrode material of the present invention, the composition formula _{A x Ni 1-z M z} O 2 (A is an element or group can be a cation, the cation valence of A y Where x · y <1 is satisfied, M is represented by a transition series element and one or more elements selected from 2A group, 3A group, 2B group, 3B group, 0 ≦ z ≦ 0.5) It is a layered nickel oxide and has a layered Li ₂ MnO ₂ type structure.

Moreover, the manufacturing method of the layered nickel oxide electrode material according to the present invention includes a composition formula ANi _1-z M _z O ₂ , wherein a part of A is desorbed by acid treatment or electrochemical ion desorption, and a cation is further removed. by in aqueous solution by performing the reduction treatment inserting the cations including, characterized in that to obtain a layered nickel oxide electrode material according to claim 1, wherein _{a x Ni 1-z M z} O 2.

  Further, the battery according to the present invention has a positive electrode containing the layered nickel oxide electrode material as a positive electrode active material, and a substance containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, silver, or this An electrolyte substance is a substance that has a negative electrode containing a substance that can reversibly insert and desorb, occlude and desorb an element, and ions of the element can move to cause an electrochemical reaction with the positive electrode and the negative electrode It is characterized by including. Further, the battery according to the present invention is characterized in that it has a positive electrode containing the layered nickel oxide electrode material as a positive electrode active material, and has a substance that can move protons to perform an electrochemical reaction with the positive electrode as an electrolyte substance. It is said.

  According to the present invention, a battery having a large discharge capacity can be realized, and there is an advantage that it can be used in various fields including a power source of an electronic device.

  The present invention will be described in more detail. As a result of earnest search for the layered nickel oxide electrode material and the battery using the same, the inventors have found that the layered nickel oxide electrode material and the battery using the layered nickel oxide electrode material and It was confirmed that a battery using the battery could be manufactured and realized, and the present invention was completed based on the recognition.

The reason is as follows. That is, the layered nickel oxide electrode material of the present invention has a layered Li ₂ MnO ₂ type structure that realizes more than one ion storage per transition metal, and has a sufficiently large ion storage position, so that it has a large capacity. Can be discharged.

  In order to stabilize the layer structure, an element which can be a cation and A which is a group can be added. Here, when the cation valence of A is y, it is necessary to satisfy x · y <1. When x · y exceeds 1, the average oxidation number of nickel becomes low, and a large capacity that is the effect of the present invention cannot be obtained. Further, as x · y is closer to 0, a larger discharge capacity is often obtained. Therefore, preferably 0 <x · y ≦ 1.0, more preferably 0 <x · y ≦ 0.5, and most preferably 0. <X · y ≦ 0.2.

  From this point of view, y is preferably 1 or 2 as A, and the elements are hydrogen, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, copper, silver, zinc, nickel, group It is preferably composed of at least one kind of tetramethylammonium group, tetraethylammonium group, tetrapropylammonium group, tetrabutylammonium group (hereinafter collectively referred to as a tetraalkylammonium group), or an ammonium ion. Aluminum, gallium, indium, strontium, yttrium, or a lanthanoid element in which y is 3 can also be used.

Further, the element M in the layered nickel oxide electrode material A _x Ni _1-z M _z O ₂ of the present invention improves the electrode reversibility of the electrode material, improves the thermal stability, and improves the storage characteristics. For this purpose, a part of nickel is replaced, and it is possible to add none at all.

  As M, one or more elements selected from transition series elements and 2A group, 3A group, 2B group, and 3B group can be used. From the viewpoint of forming a nickel main layer by solid solution with nickel, Is close to nickel, and titanium, vanadium, chromium, manganese, iron, cobalt, aluminum, and gallium are preferable. The substitution ratio z is 0 ≦ z ≦ 0.5. Further, when the substitution ratio z exceeds 0.5, the capacity based on the redox couple of nickel becomes small, which is unsuitable, preferably 0 <z ≦ 0.5, more preferably 0 <z ≦ 0. 3, most preferably 0 <z ≦ 0.2.

For layered nickel oxide electrode material _{A x Ni 1-z M z} O 2 synthesis methods of the present invention, for example, by first firing method to synthesize _{ANi 1-z M z O 2} , which, for example, alkali metal ions, It can be obtained by treating with an alkaline aqueous solution in which a hydroxide containing an alkaline earth metal ion, tetraalkylammonium ion, ammonium ion or the like as a cation is dissolved in water.

When an alkaline aqueous solution is used, hydroxide ions are oxidized to A _x Ni _1-z M _z O ₂ to generate oxygen, and at the same time, A _x Ni _1-z M _z O ₂ is reduced and contained in the solution. the cations are incorporated into the interlayer of _{a x Ni 1-z M z} O 2 to be. At this time, the cation contained in the alkaline aqueous solution may be the same as A.

Furthermore, the cation species contained between the layers can be exchanged with other ions by ion exchange. Moreover, an electrochemical method can be used alone or in combination as a treatment method. In the synthesis process of layered nickel oxide electrode material _{A x Ni 1-z M z} O 2 of the present invention, there is a case where the amount of oxygen is less decrease in the molar ratio of oxygen to the sum of nickel and M is 2 If they are close, the average valences of nickel and M are kept sufficiently high, so there is no influence on the characteristics.

  In order to form a battery electrode using the layered nickel oxide electrode material according to the present invention as an electrode active material, a mixture of the layered nickel oxide electrode material powder and a binder powder such as polytetrafluoroethylene is made of stainless steel or the like. A pressure-sensitive adhesive molding such as acetylene black is mixed with the mixture powder, or a binder powder such as polytetrafluoroethylene is added to the mixture powder as necessary. In addition, the mixture is put in a metal container, or pressure-molded on a support such as stainless steel, or dispersed in a solvent such as an organic solvent and applied to a metal substrate as a slurry. There are no particular restrictions.

  The battery according to the present invention has a positive electrode including the layered nickel 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 that can reversibly insert / desorb or occlude / desorb the element, By having as an electrolyte substance a substance that can move to cause the ions of the element to perform an electrochemical reaction with the positive electrode and the negative electrode, a battery in which the ion of the element moves between the positive electrode and the negative electrode is obtained. For example, when configuring a battery in which lithium ions move, the negative electrode can be configured to include a conventionally known material such as metallic lithium, a lithium-aluminum alloy, a lithium-carbon compound, or a lithium-containing nitride. Even when sodium, potassium, magnesium, calcium, strontium, aluminum, copper, or silver is included, it may be configured to include a conventionally known material such as a single metal, an alloy, a composite compound with carbon, or a nitride. it can. Even when sodium, potassium, magnesium, calcium, strontium, aluminum, copper, or silver is included, it may be configured to include a conventionally known material such as a single metal, an alloy, a composite compound with carbon, or a nitride. it can.

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

  Moreover, this can be used as a secondary battery by repeatedly discharging and charging the battery. Furthermore, conventionally known various materials can be used for other elements such as electrolytes, separators, battery cases, and other structural materials, and there is no particular limitation.

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

In Example 1, a layered nickel oxide was produced as follows. First, lithium nitrate and nickel hydroxide were uniformly mixed at a molar ratio of Li: Ni = 2: 1, and this was subjected to a solid phase reaction in the atmosphere at 700 ° C. for 10 hours. LiNiO ₂ was obtained by washing with water to remove excess alkali and drying. When this LiNiO ₂ is analyzed by X-ray diffraction analysis, it can be indexed with a hexagonal crystal (space group R-3m), and the lattice constants are a = 2.875 (Å) and c = 14.19 (Å). I found out.

Next, this LiNiO ₂ was mixed with a 1.0 N sulfuric acid solution at a ratio of H ⁺ / Ni = 4, stirred and reacted for 5 hours, washed with water and dried to obtain Li _0.1 NiO ₂ . Further, this Li _0.1 NiO ₂ was mixed with a 1 mol / l tetraethylammonium hydroxide solution at a ratio of TEA / Ni = 10 where the tetraethylammonium group was expressed as TEA, stirred and reacted for 5 hours, washed with water, dried By doing so, a layered nickel oxide was obtained. Let this sample be a.

The X-ray diffraction pattern of sample a is shown in FIG. When this X-ray diffraction pattern is analyzed, it can be indexed by hexagonal crystal (space group P-3m1), and the lattice constants are a = 3.1 (Å) and c = 4.7 (Å). I understood. FIG. 2 shows an X-ray diffraction pattern of the layered Li ₂ MnO ₂ . Although there is a difference in peak intensity, since it belongs to the same hexagonal crystal (space group P-3m1), it can be seen that the sample a has a layered Li ₂ MnO ₂ type structure.

In order to investigate the detailed chemical composition of this sample, an attempt was made to dissolve the sample in an acid. As a result, about 20% by weight of an insoluble component was generated, but an accurate chemical composition could not be obtained. It was confirmed that it contained nickel and oxygen. Considering that it has a Li ₂ MnO ₂ type structure, it was presumed to belong to nickel dioxide containing a decomposition product of lithium and tetraethylammonium between layers. The color was brown.

  Next, a battery including the sample a as a positive electrode active material was produced. FIG. 3 is a cross-sectional view of the battery. In FIG. 3, 1 is a sealing plate, 2 is a gasket, 3 is a positive electrode case, 4 is a negative electrode, 5 is a separator, and 6 is a positive electrode mixture pellet. First, the sample a was vacuum-dried, and then mixed with a conductive agent (acetylene black) and a binder (polytetrafluoroethylene), followed by roll molding to obtain a positive electrode mixture pellet 6.

Next, a metal lithium negative electrode 4 placed under pressure on a stainless steel sealing plate 1 is inserted into a recess of a polypropylene gasket 2, and a polypropylene microporous separator 5 and a positive electrode mixture are formed on the negative electrode 4. The pellets 6 are arranged in this order, and after impregnating an appropriate amount of a 1N solution in which LiPF ₆ is dissolved in an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate as an electrolytic solution, 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 battery was manufactured in a dry box under an argon atmosphere.

  A battery including the sample a thus produced 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 5 mA / g at 25 ° C., a capacity of 290 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 high energy density.

  In Example 2, a battery was fabricated in the same manner as in Example 1 except that the layered nickel oxide obtained by the following production method was used as the positive electrode active material.

First, lithium nitrate, nickel hydroxide and cobalt oxide were uniformly mixed at a molar ratio of Li: Ni: Co = 2.0: 0.9: 0.1, and this was mixed at 700 ° C. for 10 hours. LiNi _0.9 Co _0.1 O ₂ was obtained by solid-phase reaction in the air, washing the resulting powder with water to remove excess alkali, and drying. When this LiNi _0.9 Co _0.1 O ₂ is analyzed by X-ray diffraction analysis, it can be indexed by a hexagonal crystal (space group R-3m), and the lattice constant is a = 2.871 (Å), c = 14.18 (Å).

Next, this LiNi _0.9 Co _0.1 O ₂ was mixed with a 1.0 N sulfuric acid solution at a ratio of H ⁺ / Ni = 4, stirred and reacted for 5 hours, washed with water, and dried to give Li _{0. .1} Ni _0.9 Co _0.1 O ₂ was obtained. Further, this Li _0.1 Ni _0.9 Co _0.1 O ₂ is mixed with a 1 mol / l tetraethylammonium hydroxide solution at a ratio of TEA / Ni = 10, stirred and reacted for 5 hours, washed with water and dried. As a result, layered nickel oxide was obtained. Let this sample be b.

Sample b also showed an X-ray diffraction pattern similar to that of sample a, and was found to have a layered Li ₂ MnO ₂ type structure. Further, in order to investigate the detailed chemical composition of the sample, an attempt was made to dissolve the sample in an acid. As a result, about 20% by weight of an insoluble component was generated, but an accurate chemical composition could not be obtained. It was confirmed to contain nickel, cobalt and oxygen. Considering that it has a Li ₂ MnO ₂ type structure, it was inferred that it belonged to nickel dioxide containing a decomposition product of lithium and tetraethylammonium between the layers and partially replacing nickel with cobalt.

  A battery including the sample b thus produced 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 5 mA / g at 25 ° C., a capacity of 280 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 high energy density. It was also found that repeated charge / discharge is possible.

  In Example 3, a conductive agent of 20% by weight is added to the sample a produced in Example 1 to make a positive electrode, a 3 mol / l aqueous solution in which sodium chloride is dissolved is used as an electrolytic solution, and a zinc plate is used as a negative electrode. An aqueous battery was prepared. When discharged to 0.7 V at a current density of 10 mA / g at 25 ° C., a capacity of 290 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 high energy density. It was also found that repeated charge / discharge is possible.

In Examples 1 to 3, a specific example of a method for producing a nickel-containing oxide and a specific example of a battery using the nickel-containing oxide were shown. In general, the electrode material has a composition formula A _x Ni _1-z M _z O ₂ ( A is an element and group to be a cation, and satisfies x · y <1 when the cation valence of A is y, M is selected from a transition series element, 2A group, 3A group, 2B group, 3B group A layered nickel oxide represented by one or more elements, 0 ≦ z ≦ 0.5), and having a layered Li ₂ MnO ₂ type structure, wherein the battery comprises the layered nickel oxide electrode material. Has a positive electrode as a positive electrode active material, and can reversibly insert / desorb or occlude / desorb a substance containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, silver, or this element Stuff Or a material capable of performing migration for causing an ion reaction of the element with the positive electrode and the negative electrode as an electrolyte substance, or the layered nickel oxide electrode material In the case of having a positive electrode contained as a positive electrode active material and having a substance as an electrolyte material capable of moving protons to perform an electrochemical reaction with the positive electrode, it goes without saying that the same effect is produced. Nor.

(Comparative Example 1)
In Comparative Example 1, a lithium battery was produced in the same manner as in Example 1 except that the positive electrode active material sample c obtained by the following production method was used. First, lithium nitrate and nickel hydroxide were uniformly mixed at a molar ratio of Li: Ni = 2: 1, and this was subjected to a solid phase reaction in the atmosphere at 700 ° C. for 10 hours. LiNiO ₂ was obtained by washing with water to remove excess alkali and drying. When this LiNiO ₂ is analyzed by X-ray diffraction analysis, it can be indexed with a hexagonal crystal (space group R-3m), and the lattice constants are a = 2.875 (Å) and c = 14.19 (Å). I found out. Let this sample be c.

  A battery including the sample c thus produced as a positive electrode active material was tested in a dry box under an argon atmosphere. When charged to 4.3 V at a current density of 5 mA / g at 25 ° C. and then discharged to 2.0 V, a capacity of 200 mAh / g per positive electrode weight was obtained. Compared with this battery, it can be seen that the battery having the positive electrode active material produced in the example of the present invention has a large discharge capacity.

(Comparative Example 2)
In Comparative Example 2, an aqueous battery was prepared in the same manner as in Example 3 except that the positive electrode active material sample c produced in Comparative Example 1 was used. When discharged to 0.7 V at a current density of 10 mA / g at 25 ° C., a capacity of 220 mAh / g per positive electrode weight was obtained. Compared with this battery, it can be seen that the battery having the positive electrode active material produced in the example of the present invention has a large discharge capacity.

  The present invention is characterized by using the layered nickel oxide electrode material having the structure described in claim 1 in order to provide a battery having a large discharge capacity.

The X-ray-diffraction figure of the sample a in the Example of this invention measured using the copper K alpha ray. It was measured using a copper Kα _beam, X-ray diffraction pattern of Li 2 MnO _2. Sectional drawing which shows the structural example of the coin-type battery in the Example of this invention.

Explanation of symbols

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

Claims (12)

Composition formula A _x Ni _1-z M _z O ₂ (A is an element and group to be a cation, x satisfies y · 1 when the cation valence of A is y, M is a transition series element and 2A A layered nickel oxide represented by one or more elements selected from Group 3A, Group 2B, Group 3B, Group 3B, 0 ≦ z ≦ 0.5), and has a layered Li ₂ MnO ₂ type structure, Layered nickel oxide electrode material. The layered nickel oxide electrode material according to claim 1, wherein the cation valence of A is 1, 2 or 3. The A is at least one selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, copper, silver, zinc, nickel, tetraalkylammonium groups and ammonium groups. The layered nickel oxide electrode material according to claim 2. 4. The layered nickel oxide electrode material according to claim 1, wherein x · y is 0 <x · y <1. 5. The layered nickel oxide electrode material according to claim 4, wherein x · y is 0 <x · y <0.2. The layered nickel according to any one of claims 1 to 5, wherein the M is at least one selected from the group consisting of aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, aluminum, and gallium. Oxide electrode material. The layered nickel oxide electrode material according to claim 1, wherein z is 0 <z ≦ 0.3. The layered nickel oxide electrode material according to claim 7, wherein z is 0 <z ≦ 0.2. A part of A is removed from the composition formula ANi _1-z M _z O ₂ by acid treatment or electrochemical ion desorption, and further the reduction treatment is performed in an aqueous solution containing a cation to insert the cation. the method for producing a layered nickel oxide electrode material characterized by obtaining a layered nickel oxide electrode material according to claim 1, wherein _{a x Ni 1-z M z} O 2. 10. The method for producing a layered nickel oxide electrode material according to claim 9, wherein the reduction treatment is performed by decomposition of hydroxide ions in an alkaline aqueous solution. A positive electrode containing the layered nickel oxide electrode material according to claim 1 as a positive electrode active material, a substance containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, silver, or this element reversibly Having a negative electrode containing a substance that can be inserted / desorbed or occluded / desorbed as an electrolyte substance, and a substance capable of migrating ions of the element to perform an electrochemical reaction with the positive electrode and the negative electrode as an electrolyte substance. Battery characterized. A battery comprising a positive electrode containing the layered nickel oxide electrode material according to claim 1 as a positive electrode active material, and having a substance capable of transferring protons to cause an electrochemical reaction with the positive electrode as an electrolyte substance. .

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