JP2001332256A - Material for electrode, its manufacturing method and cell therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for an electrode, that is composed of a layer- like manganese dioxide and has a good cycle property, its manufacturing method and a cell that comprises the layer-like manganese dioxide for the electrode material as an activating material for a positive electrode. SOLUTION: A dehydrated layer-like manganese dioxide expressed in formula (1), its manufacturing method and the cell comprising the compound as the positive electrode are used: (1) MXMnO2-δ.nH2O [M is an element or more comprising any elements of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Al, Ni, La, Bi, 0.1<=X<=0.5, -2.0<=δ<=0.2 and 0.5<=n<=1.0] A concrete example of a coin type cell is composed of a sealing plate 1, a gasket 2, a positive electrode case 3, a negative electrode 4, and a mixture pellet for the positive electrode 6. It provides the cell featuring a good cycle property and many applications to various fields, including the application as a power source for a number of electronic devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode material, a method for producing the same, and a battery containing the electrode material as a positive electrode active material, and more particularly to a technique for providing a battery having good cycle characteristics.

[0002]

2. Description of the Related Art General formula M_XMnO_2-δ・ NH_Two
O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
One containing any of r, Ba, Al, Ni, La, and Bi
Or more elements, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0)
Ngan is the cathode active material of current lithium-ion batteries
LiCoO_TwoInexpensive and highly heat-stable material
It has been proposed. However, the general formula M _XMnO_2-δ・ N
H_TwoO (M = Li, Na, K, Rb, Cs, Mg, C
a, Sr, Ba, Al, Ni, La, Bi
One or more elements, 0.1 ≦ X ≦ 0.5, −0.2 ≦
δ ≦ 0.2, 0.5 ≦ n ≦ 1.0)
Manganese oxide contains water molecules.
It escapes into the electrolyte and reacts with the negative electrode, resulting in poor cycle characteristics.
There was a disadvantage that.

In addition, when heat dehydration is performed, there is a problem that a structural change occurs, and the structure changes to a structure having poor cycle characteristics.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned current problems and provides an electrode material having the above-mentioned layered manganese dioxide and good cycle characteristics, a method for producing the same, and an electrode for the same. An object of the present invention is to provide a battery including a layered manganese dioxide material as a positive electrode active material.

[0005]

In order to achieve the above object, an electrode material according to the present invention is characterized in that it is a dehydrated layered manganese dioxide represented by the following general formula. Formula _{M X MnO 2-δ · nH} 2 O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
one or more elements including any of r, Ba, Al, Ni, La and Bi, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0) In addition, the method for producing an electrode material according to the present invention comprises the steps of: forming a layered manganese dioxide represented by the following general formula into an organic solvent with an alkali metal, an alkaline earth metal, It is characterized by being simultaneously soaked with at least one of molecular sieves and activated alumina.

[0006] formula _{M X MnO 2-δ · nH} 2 O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
one or more elements including any of r, Ba, Al, Ni, La and Bi, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0) Further, the battery of the present invention has a positive electrode using the layered manganese dioxide described above as a positive electrode active material for a battery, and includes lithium, sodium, potassium, and magnesium. Having a negative electrode containing a substance containing any of calcium, strontium, aluminum, copper and silver or a substance capable of reversibly inserting / desorbing or occluding / desorbing this element, wherein ions of the element are present in the positive electrode and the positive electrode. It is characterized in that a substance capable of performing a transfer for performing an electrochemical reaction with the negative electrode is contained as an electrolyte substance.

The present invention will be described in more detail. The inventor has conducted a diligent search for a production method for providing layered manganese dioxide with good cycle characteristics, and a battery containing layered manganese dioxide dehydrated by the method as a positive electrode active material,
By using a battery containing the layered manganese dioxide dehydrated by the method for producing a layered manganese dioxide as a positive electrode active material, to produce a battery having better cycle characteristics than before,
The present inventors have confirmed that the present invention can be realized and completed the present invention based on the recognition.

The electrode material of the present invention has the general formula M _x MnO
_2-δ · nH ₂ O (M = Li, Na, K, Rb, Cs, M
g, one or more elements including Ca, Sr, Ba, Al, Ni, La, Bi, 0.1 ≦ X ≦ 0.5, −
(0.2 ≦ δ ≦ 0.2, 0.5 ≦ n ≦ 1.0) obtained by dehydrating layered manganese dioxide.

In the above general formula, X and δ are 0.1 ≦ X ≦ 0.5 and −0.2 ≦ δ ≦ 0.2, respectively.
These vary depending on the type of M and the synthesis method. And n
Is 0.5 ≦ n ≦ 1.0, which also varies depending on the type of M and the synthesis method.

According to the method for producing an electrode material of the present invention, at least one of an alkali metal, an alkaline earth metal, molecular sieves and activated alumina is immersed in an organic solvent at the same time as the layered manganese dioxide. Dehydrate manganese dioxide.

As a result, the water that has escaped into the organic solvent reacts with the alkali metal or alkaline earth metal, or is absorbed by molecular sieves or activated alumina, and the dehydration from the layered manganese dioxide proceeds continuously. By using the method of the present invention, dehydration can be performed efficiently and sufficiently at room temperature, and a battery having good cycle characteristics can be formed.

Further, the method for producing an electrode material of the present invention has an advantage that dehydration can be performed without causing a structural change.

The organic solvent used for dehydration includes alkali metals, alkaline earth metals, molecular sieves,
Does not react with activated alumina, the general formula _{M X MnO 2-δ · nH} 2
O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
one or more elements including any of r, Ba, Al, Ni, La and Bi, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0), as long as it does not react with the layered manganese dioxide represented by the formula:
For example, when lithium metal is used for dehydration, dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, or the like can be used.

To form a battery positive electrode using the dehydrated layered manganese dioxide electrode material of the present invention as a positive electrode active material, a mixture of the layered manganese dioxide powder and a binder powder such as polytetrafluoroethylene is used. Press molding on a support such as stainless steel. Alternatively, a conductive powder such as acetylene black is mixed to impart conductivity to the active material powder, and a binder powder such as polytetrafluoroethylene is further added as necessary, and the mixture is mixed with a metal. It is formed by means such as placing in a container, press-molding 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.

In the battery using the layered manganese dioxide as a positive electrode active material, a material containing any of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, and silver or a reversible insertion / desorption of the element is used. Alternatively, a negative electrode containing a substance that can be inserted and extracted can be used, and the element ions can be transferred to the positive electrode and the negative electrode by electrochemical reaction with the positive electrode and the negative electrode. And the battery that moves between the negative electrode. 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.

In a battery using the layered manganese dioxide as a positive electrode active material, for example, methoxyethane,
Diethoxyethane, 2-methyltetrahydrofuran, ethylene carbonate, propylene carbonate, methyl formate, dimethyl sulfoxide, acetonitrile,
Butyrolactone, dimethylformamide, dimethyl carbonate, diethyl carbonate, sulfolane, non-aqueous electrolyte solvent in which a salt such as alkaline earth metal is dissolved in an organic solvent such as ethyl methyl carbonate, or a solid electrolyte, a polymer electrolyte, the organic A polymer electrolyte carrying a solvent or the like can be used.

By repeatedly discharging and charging the battery, the battery can be used as a secondary battery.

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

[0019]

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.

[0020]

Embodiment 1 FIG. 1 is a cross-sectional view of a coin-type battery which is a specific example of a battery using a layered manganese dioxide as an electrode material according to the present invention as a positive electrode active material, wherein 1 is a sealing plate, and 2 is a gasket. Reference numeral 3 denotes a positive electrode case, 4 denotes a negative electrode, 5 denotes a separator, and 6 denotes a positive electrode mixture pellet.

As the positive electrode active material, a sample a was manufactured as follows, and a sample b obtained by dehydrating the sample a was used. First, manganese chloride was dissolved in water from which oxygen was degassed through an argon gas, and the mixture was stirred well in an argon atmosphere. Then, a sodium hydroxide solution was mixed at an atomic ratio of Mn: Na = 1: 50 to form a mixture. The mixture was further stirred so that the precipitate became uniform. Next, it is sufficiently oxidized with oxygen, the solid content is filtered out of the solution, taken out, and further washed with water to remove the excess alkali content, and dried to obtain layered manganese dioxide Na _0.28 MnO ₂ .0.7H ₂ O. Obtained. This sample is designated as a. The sample a thus produced was immersed in dimethyl carbonate together with lithium metal arranged so as not to come into contact with the sample, and left to stand for 24 hours to dehydrate. Then, after taking out the metallic lithium, a sample was taken out from the dimethyl carbonate by filtration and dried at room temperature. X
Line diffraction revealed that this sample had a structure similar to that of sample a. This sample is designated as b.

The powder of the sample b was mixed with a conductive agent (acetylene black) and a binder (polytetrafluoroethylene), and then roll-formed, and then mixed with a positive electrode mixture pellet 6 (thickness 0.5 mm, diameter 15 mm). did.

Next, a negative electrode 4 made of metallic lithium, which is 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 separator 5 made of polypropylene and made of polypropylene is placed on the negative electrode 4. After arranging the positive electrode mixture pellets 6 in this order, injecting and impregnating 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,
A coin-type battery having a thickness of 2 mm and a diameter of 23 mm was produced by covering and swaging a stainless steel positive electrode case 3.

A battery using the thus prepared and dehydrated sample b as a positive electrode active material was discharged to 2.0 V and charged to 4.0 V at a current density of 0.1 mA / cm ^2. Repeated. Then, the cycle was stably performed until the tenth discharge, and the tenth discharge capacity reached 80% of the first discharge capacity. Therefore, by dehydrating the layered manganese dioxide by this manufacturing method, a battery having good cycle characteristics can be realized.

[0025]

Example 2 In Example 2, a lithium battery was produced in the same manner as in Example 1, except that Sample c was used in which Sample a was dehydrated as follows. First, sample a was immersed in propylene carbonate together with lithium metal arranged so as not to come into contact with the sample, and left for 24 hours to dehydrate. Then, after removing metallic lithium, a sample was removed by filtration from propylene carbonate and dried at room temperature. X-ray diffraction revealed that this sample had a structure similar to that of sample a, and this sample is referred to as c.

A battery using the thus prepared and dehydrated sample c as a positive electrode active material was discharged to 2.0 V and charged to 4.0 V at a current density of 0.1 mA / cm ^2. Repeated. Then, the cycle was stably performed until the tenth discharge, and the tenth discharge capacity reached 80% of the first discharge capacity. Therefore, by dehydrating the layered manganese dioxide by this manufacturing method, a battery having good cycle characteristics can be realized.

[0027]

Embodiment 3 In Embodiment 3, a sample d was manufactured as follows.
Except that a sample e obtained by dehydrating this sample d was used.
A lithium battery was produced in the same manner as in Example 1. First, sample a
Is dispersed in a lithium chloride solution, and released for 24 hours.
And then filtered off and dried. Repeat the same work twice
After that, remove the sample from the solution by filtration and wash with water.
To remove lithium chloride and dry the layer.
Manganese dioxide Li _0.28MnO_Two・ 0.9H_TwoGet O
Was. This sample is referred to as d.

The sample d thus produced was immersed in dimethyl carbonate together with lithium metal arranged so as not to come into contact with the sample, and left to stand for 24 hours to dehydrate. Then, after taking out metallic lithium, a sample was taken out from dimethyl carbonate by filtration and dried at room temperature. X
Line diffraction revealed that this sample had a structure similar to that of sample d. This sample is referred to as e.

A battery using the thus prepared and dehydrated sample e as a positive electrode active material was discharged to 2.0 V and charged to 4.0 V at a current density of 0.1 mA / cm ^2. Repeated. Then, the cycle was stably performed until the tenth discharge, and the tenth discharge capacity reached 90% of the first discharge capacity. Therefore, by dehydrating the layered manganese dioxide by this manufacturing method, a battery having good cycle characteristics can be realized.

[0030]

Comparative Example 1 In Comparative Example 1, a lithium battery was produced in the same manner as in Example 1, except that Sample a was used as the layered manganese dioxide not subjected to dehydration in the production method of the present invention.

This battery was repeatedly discharged at a current density of 0.1 mA / cm ^{2 to} 2.0 V and charged to 4.0 V repeatedly. Then, the second discharge capacity was 15% of the first discharge capacity. Compared with this battery, it is found that the battery including the sample dehydrated in the example of the present invention as the positive electrode active material has better cycle characteristics.

[0032]

Comparative Example 2 In Comparative Example 2, a lithium battery was fabricated in the same manner as in Example 1, except that Sample a, which was heat-treated as follows, was used for Sample a. First, the powder of the sample a was heat-treated at 200 ° C. for 24 hours in the air. The pattern obtained by X-ray diffraction was different from that of Sample a, and it was found that a structural change had occurred.

The battery manufactured and heat-treated using the sample f as the positive electrode active material was discharged to 2.0 V and charged to 4.0 V at a current density of 0.1 mA / cm ^2. Repeated. Then, the tenth discharge capacity was 65% of the first discharge capacity. Compared with this battery, it is found that the battery including the sample dehydrated in the example of the present invention as the positive electrode active material has better cycle characteristics.

[0034]

Comparative Example 3 In Comparative Example 3, a lithium battery was produced in the same manner as in Example 1, except that Sample d was used as the layered manganese dioxide not subjected to dehydration in the production method of the present invention.

The battery was repeatedly discharged to 2.0 V and charged to 4.0 V at a current density of 0.1 mA / cm ² . Then, the second discharge capacity was 15% of the first discharge capacity. Compared with this battery, it is found that the battery including the sample dehydrated in the example of the present invention as the positive electrode active material has better cycle characteristics.

[0036]

As described above, according to the method for producing layered manganese dioxide according to the present invention and the battery containing the layered manganese dioxide produced by the method as a positive electrode active material, a battery having good cycle characteristics can be obtained. It can be realized and can be used in various fields including power supply of various electronic devices.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration example of a coin-type battery according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Gasket 3 Positive electrode case 4 Negative electrode 5 Separator 6 Positive electrode material pellet

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoji Sakurai 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 4G048 AA04 AA05 AC06 AE05 5H029 AJ05 AK03 AL06 AL11 AL12 AL03 AM05 AM07 BJ03 BJ16 CJ13 DJ16 DJ17 HJ02 5H050 AA07 BA17 CA09 CB07 CB12 DA09 EA02 EA10 EA24 FA17 FA18 GA13 HA02

Claims (3)

[Claims] An electrode material comprising dehydrated layered manganese dioxide represented by the following general formula: Formula _{M X MnO 2-δ · nH} 2 O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
one or more elements including any of r, Ba, Al, Ni, La and Bi, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0) 2. An electrode characterized in that a layered manganese dioxide represented by the following general formula is simultaneously immersed in an organic solvent with at least one of an alkali metal, an alkaline earth metal, molecular sieves and activated alumina. Material manufacturing method. Formula _{M X MnO 2-δ · nH} 2 O (M = Li, Na, K, Rb, Cs, Mg, Ca, S
one or more elements including any of r, Ba, Al, Ni, La and Bi, 0.1 ≦ X ≦ 0.5, −0.2 ≦ δ ≦
0.2, 0.5 ≦ n ≦ 1.0) 3. A substance having a positive electrode containing the layered manganese dioxide according to claim 1 as a positive electrode active material, and containing any one of lithium, sodium, potassium, magnesium, calcium, strontium, aluminum, copper, and silver, or an element thereof. Having a negative electrode containing a substance capable of reversibly inserting / desorbing or occluding / desorbing, and including, as an electrolyte substance, a substance capable of performing an ion reaction of the element for the electrochemical reaction with the positive electrode and the negative electrode A battery comprising: