JP3443224B2 - Non-aqueous electrolyte battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery that includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and uses a positive electrode material mainly containing manganese oxide for the positive electrode. The present invention relates to a non-aqueous electrolyte battery having an improved positive electrode material.

[0002]

2. Description of the Related Art In recent years, as one of new type batteries with high output and high energy density, a non-aqueous electrolyte battery using a non-aqueous electrolyte such as a non-aqueous electrolyte solution and utilizing oxidation and reduction of lithium has been used. It became so.

Here, in such a non-aqueous electrolyte battery, various metal oxides capable of inserting and extracting lithium have been conventionally used as a positive electrode material for the positive electrode, but the material is inexpensive. From the viewpoint of being obtained, the use of a material mainly containing manganese oxide as the positive electrode material has been studied.

However, in such a non-aqueous electrolyte battery, since the voltage at the positive electrode is 3 V or higher, when a material mainly containing manganese oxide is used as the positive electrode material, this manganese oxide is mainly contained. The material reacts by contacting with a non-aqueous electrolyte solution or the like in the non-aqueous electrolyte battery, thereby causing self-discharge, the storage stability in this non-aqueous electrolyte battery is lowered, especially when used as a secondary battery, There are problems that the storage property is significantly deteriorated, and the charge / discharge cycle characteristics are deteriorated.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems in a non-aqueous electrolyte battery using a positive electrode material mainly containing manganese oxide for the positive electrode. Manganese oxide in the material, by suppressing the contact and reaction with a non-aqueous electrolyte in a non-aqueous electrolyte battery, to reduce the deterioration of storage stability due to self-discharge, especially when used as a secondary battery ,
It is an object to obtain excellent storability and charge / discharge cycle characteristics.

[0006]

In order to solve the above problems, a non-aqueous electrolyte battery according to the present invention comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, and the positive electrode mainly contains manganese oxide. In a non-aqueous electrolyte battery using a material, the manganese oxide is mainly used as the positive electrode.
Ammonium sulfate is added to the positive electrode material
Added in the range of 0.1 to 30 mol% relative to manganese in the product.
And heat-treat it with ammonium sulfate and manganese oxide
That is, a composite oxide is used.

Here, as in the non-aqueous electrolyte battery according to the present invention, a positive electrode material mainly containing manganese oxide is used, and an ammonium sulfate salt is added to manganese in the manganese oxide.
When added in the range of 0.1 to 30 mol% and heat-treated, the manganese oxide and ammonium sulfate salt react with each other on the surface of the manganese oxide in the positive electrode material to form these complex oxides. Manganese oxide is protected by the complex oxide with and the reaction with the non-aqueous electrolyte is suppressed, which reduces self-discharge and improves storage stability, especially when used as a secondary battery. It is considered that the storage stability is significantly improved and the charge / discharge cycle characteristics are also improved.

When the ammonium sulfate salt is added to the positive electrode material mainly containing manganese oxide as described above and the heat treatment is performed, the amount of ammonium sulfate salt to be added is
If it is less than 0.1 mol%, the amount of the complex oxide formed by reacting with ammonium sulfate decreases, and manganese oxide cannot sufficiently suppress self-discharge by reacting with non-aqueous electrolyte. , The amount of ammonium sulfate salt is 30
When the content is more than mol% , the characteristics of the manganese oxide as a positive electrode material are deteriorated, lithium cannot be occluded and released sufficiently, the discharge characteristics are deteriorated, and self-discharge is increased.

Here, when the ammonium sulfate salt is added to the positive electrode material containing manganese oxide as the main component and the heat treatment is performed, these powders may be simply mixed. In order to uniformly apply the ammonium sulfate salt to the oxide, it is preferable to add these to a solvent such as water to form a slurry and heat-treat.

In addition, as described above, when the ammonium sulfate salt is added to the positive electrode material mainly containing manganese oxide and then heat treatment is performed, if the heat treatment temperature is low or the treatment time is short, the manganese oxide is The complex oxide is not sufficiently formed by the reaction between the ammonium sulfate and ammonium sulfate, and the manganese oxide reacts with the non-aqueous electrolyte to cause self-discharge, while the temperature is too high or the treatment time is long. If it is too high, the manganese oxide is deteriorated by this, and the characteristics of the positive electrode material are deteriorated. Therefore, it is preferable to perform heat treatment at a temperature in the range of 300 to 430 ° C. for 30 minutes to several hours.

Here, the positive electrode material mainly composed of manganese oxide used for the positive electrode may be composed of only manganese oxide or may be a composite material of manganese oxide and other metal. In particular, when it is used as a positive electrode of a secondary battery that utilizes oxidation and reduction of lithium, it is preferable to use a composite oxide of manganese and lithium, which has an excellent ability to store and release lithium ions. preferable.

On the other hand, various ammonium sulfate salts can be used as the ammonium sulfate salt to be added to the positive electrode material mainly containing manganese oxide, for example, (NH
_{4) 2 SO 4, Fe (} NH 4) 2 (SO 4) 2 · 6H 2
O, FeNH ₄ (SO ₄ ) ₂ · 12H ₂ O, Co (NH
_{4) 2 (SO 4) 2} · 6H 2 O, Ni (NH 4) 2 (S
_{O 4) 2 · 6H 2 O} , AlNH 4 (SO 4) 2 · 12H
₂ O or the like can be used, and in particular, it contains any one of divalent iron, divalent cobalt, and aluminum from the viewpoint of suppressing self-discharge due to the reaction between the manganese oxide and the nonaqueous electrolytic solution. Fe (NH ₄ ) ₂ which is an ammonium sulfate salt
_{(SO 4) 2 · 6H 2} O, Co (NH 4) 2 (SO 4) 2
It is preferable to use 6H ₂ O and AlNH ₄ (SO ₄ ) ₂ · 12H ₂ O.

Further, in the non-aqueous electrolyte battery according to the present invention, as a negative electrode material used for the negative electrode, a material generally used conventionally can be used. For example, as described above, oxidation and reduction of lithium can be performed. When used as a negative electrode in a used secondary battery, lithium metal, a carbon material such as graphite, coke, or an organic material calcined material, which is a material capable of inserting and extracting lithium ions, and Li,
-Al, Li-In, Li-Sn, Li-Pb, Li-
Bi, Li-Ga, Li-Sr, Li-Si, Li-Z
Lithium alloys such as n, Li-Cd, Li-Ca and Li-Ba can be used.

Further, in the non-aqueous electrolyte battery of the present invention, a known non-aqueous electrolyte or polymer solid electrolyte can be used as the non-aqueous electrolyte, and a known solvent as the non-aqueous electrolyte is also used. Can be used
For example, organic solvents such as propylene carbonate, ethylene carbonate, γ-butyrolactone, dimethyl carbonate, dimethyl sulfoxide, acetonitrile, butylene carbonate, 1,2-dimethoxyethane, and diethyl carbonate can be used alone or in combination of two or more. As the solute to be dissolved in this solvent, a known solute can be used. For example, when lithium is used as an active material, lithium trifluoromethanesulfonate LiCF ₃ SO ₃ and lithium hexafluorophosphate LiPF _{6 are used.} , Lithium perchlorate LiCl
O ₄ , lithium tetrafluoroborate LiBF ₄ , trifluoromethanesulfonic acid imide lithium LiN (CF
Lithium compounds such as ₃ SO ₂ ) ₂ can be used.

Also, when a polymer solid electrolyte is used, a known polymer can be used as the polymer constituting the polymer solid electrolyte, and in particular, a polymer having a high ionic conductivity with respect to lithium ions and the like can be used. It is preferable to use, for example, polyethylene oxide, polypropylene oxide, polyethyleneimine, etc. are preferably used,
It is also possible to add the above-mentioned solute together with the above-mentioned solvent to this polymer to form a gel for use.

[0016]

EXAMPLES Hereinafter, the non-aqueous electrolyte battery according to the present invention will be specifically described with reference to examples, and comparative examples will be given. In the non-aqueous electrolyte battery according to this example, the self-discharge rate becomes low. Reveal that the storage properties are improved. However, the non-aqueous electrolyte battery according to the present invention is not limited to the ones shown in the following examples, and can be implemented by appropriately changing it without departing from the scope of the invention.

Example 1 In the non-aqueous electrolyte battery of this example, the positive electrode and the negative electrode were prepared as follows, and the non-aqueous electrolyte solution was prepared as follows:
A coin type non-aqueous electrolyte secondary battery having an outer diameter of 24.0 mm and a thickness of 3.0 mm as shown in FIG. 1 was obtained.

[Preparation of Positive Electrode] In preparing the positive electrode, manganese dioxide MnO ₂ was used as the positive electrode material, while (NH ₄ ) ₂ SO ₄ was used as the ammonium sulfate salt, and this (NH ₄ ) ₂ SO ₄ was used. It was added at a ratio of 5 mol% with respect to manganese in MnO ₂ , and this was added to 375
A positive electrode material composed of MnO ₂ which has been heat-treated at 2 ° C. for 2 hours and to which (NH ₄ ) ₂ SO ₄ has been added and heat-treated,
Carbon powder, which is a conductive agent, and fluororesin powder, which is a binder, are mixed in a weight ratio of 80:10:10, and the mixture is pressure-molded into a disk shape, which is then dried by heating at 250 ° C. It processed and produced the positive electrode.

[Preparation of Negative Electrode] In preparing the negative electrode, a rolled plate of lithium-aluminum alloy was punched into a predetermined size to prepare a disc-shaped negative electrode.

[Preparation of Non-Aqueous Electrolyte Solution] To prepare a non-aqueous electrolyte solution, hexafluoro as a solute is added to a mixed solvent prepared by mixing ethylene carbonate and 1,2-dimethoxyethane at a volume ratio of 1: 1. Lithium phosphate LiPF
₆ was dissolved at a ratio of 1 mol / l to prepare a non-aqueous electrolytic solution.

[Production of Battery] To produce a battery, as shown in FIG. 1, the above-mentioned non-aqueous electrolyte was impregnated between the disk-shaped positive electrode 1 and negative electrode 2 produced as described above. The separator 3 is sandwiched, and these are housed in the battery can 4 formed by the positive electrode can 4a and the negative electrode can 4b, and the positive electrode 1 is connected to the positive electrode can 4a through the positive electrode current collector 5, while the negative electrode 2 was connected to the negative electrode can 4b via the negative electrode current collector 6, and the positive electrode can 4a and the negative electrode can 4b were electrically insulated by the insulating packing 7 made of polypropylene to produce a non-aqueous electrolyte battery. Then, the chemical energy generated inside the non-aqueous electrolyte battery was taken out as electric energy from both terminals of the positive electrode can 4a and the negative electrode can 4b.

(Comparative Example 1) In the nonaqueous electrolyte battery of Comparative Example 1, manganese dioxide MnO _{2 was} mixed with ammonium sulfate (NH 3
₄ ) A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that ₂ SO ₄ was not added.

(Example 2) In the non-aqueous electrolyte battery of Example 2, in producing a positive electrode, the atomic ratio of manganese to lithium was changed to 70:30 instead of manganese dioxide MnO _2. The above manganese-lithium composite oxide is used, and the above ammonium sulfate salt (NH ₄ ) ₂ SO ₄ is added at a ratio of 5 mol% to manganese in this manganese-lithium composite oxide. A non-aqueous electrolyte battery was prepared in the same manner as in Example 1 above.

(Comparative Example 2) In the nonaqueous electrolyte battery of Comparative Example 2, the same manganese to lithium atomic ratio as in Example 2 was 70:30 when the positive electrode was prepared.
The manganese-lithium composite oxide having the above ratio is used. In this comparative example, the above-mentioned ammonium sulfate salt (N
H ₄₎ was not exert ₂ SO _4, for otherwise, was used to fabricate a non-aqueous electrolyte battery in the same manner as in Example 1.

Next, with respect to the nonaqueous electrolyte batteries of Examples 1 and 2 and Comparative Examples 1 and 2 produced as described above, the nonaqueous electrolyte batteries immediately after the production of these nonaqueous electrolyte batteries and After storage at 80 ° C. for 2 months, a non-electrolyte battery that had been stored for 2 months was prepared, and each of these non-aqueous electrolyte batteries was discharged to 2 V under the conditions of a discharge temperature of 25 ° C. and a discharge resistance of 1 kΩ to obtain the discharge capacity before storage. The discharge capacity after storage was measured, and the self-discharge rate in each of the non-aqueous electrolyte batteries of Examples 1 and 2 and Comparative Examples 1 and 2 was calculated by the following formula (1),
The results are shown in Table 1 below. Self-discharge rate = 100 x (1-discharge capacity after storage / discharge capacity before storage) (1)

[0026]

[Table 1]

As is clear from this result, Example 1 was used in which manganese dioxide or manganese-lithium composite oxide was heat-treated by adding the ammonium sulfate salt (NH ₄ ) ₂ SO ₄ to the positive electrode material. , 2 each have a significantly lower self-discharge rate than the non-aqueous electrolyte batteries of Comparative Examples 1 and 2 in which the ammonium sulfate salt is not added as described above, and the storage stability is significantly improved. It was

(Examples 3 to 7) In the non-aqueous electrolyte batteries of Examples 3 to 7, in producing the positive electrode, the atomic ratio of manganese to lithium was 70:30, which was the same as in Example 2 above. The resulting manganese-lithium composite oxide was added to the manganese in the manganese-lithium composite oxide, and the ammonium sulfate salt shown in Table 2 below was added at a ratio of 5 mol%. Each non-aqueous electrolyte battery was produced in the same manner as in Example 1. Then, for each of the nonaqueous electrolyte batteries of Examples 3 to 7, the self-discharge rate was determined in the same manner as in the above case, and the results are also shown in Table 2.

[0029]

[Table 2]

As a result, each of the nonaqueous electrolyte batteries of Examples 3 to 7 using the positive electrode material obtained by adding the ammonium sulfate salt as described above to the composite oxide of manganese and lithium and performing the heat treatment was As in the case of the non-aqueous electrolyte batteries of Nos. 1 and 2, the self-discharge rate was remarkably reduced and the storability was significantly improved as compared with the non-aqueous electrolyte batteries of Comparative Examples 1 and 2 in which no ammonium sulfate salt was added. , Especially Fe (NH ₄ ) containing divalent iron as its ammonium sulfate salt
₂ (SO ₄₎ and ₂ · 6H ₂ O, C containing divalent cobalt
_{o (NH 4) 2 (SO} 4) and ₂ · 6H ₂ O, in the case of using the _{AlNH 4 (SO 4) 2 ·} 12H 2 O containing aluminum, self-discharge rate is further lowered, storage stability It was even better.

(Experimental Examples 1 to 8) In these Experimental Examples, the manganese-lithium atomic ratio was 70:30 when producing the positive electrode, as in the case of the above-described Example 2.
Using the manganese-lithium composite oxide with the ratio of
With respect to manganese in this manganese-lithium composite oxide, the above ammonium sulfate salt (NH ₄ ) ₂ SO ₄
The amount (mol%) to be added was changed as shown in Table 3 below, and other than that, each nonaqueous electrolyte battery was manufactured in the same manner as in each of the above-described Examples.

The self-discharge rates of the non-aqueous electrolyte batteries of the respective experimental examples thus produced were obtained in the same manner as in the above case, and the results are also shown in Table 3.

[0033]

[Table 3]

As is clear from this result, manganese
Ammonium sulfate salt (NH
₄₎ Upon is added ₂ SO _4, the amount of the ammonium salt (NH _{4) 2} SO _4, relative to the manganese of the manganese-lithium complex oxide from 0.1 to 30
In each of the nonaqueous electrolyte batteries of Experimental Examples 2 to 7 added in the range of mol%, the addition amount of the ammonium sulfate salt was 0.0.
Compared to the non-aqueous electrolyte battery of Experimental Example 1 with a small amount of 5 mol% and the non-aqueous electrolyte battery of Experimental Example 8 with a large addition amount of 40 mol%, the self-discharge rate was significantly reduced, and the non-aqueous electrolyte excellent in storage characteristics was used. From the standpoint of obtaining an electrolyte battery, ammonium sulfate is added to manganese in a positive electrode material mainly containing manganese oxide such as manganese-lithium composite oxide in an amount of 0.
It was preferable to add in the range of 1 to 30 mol%.

[0035]

As described in detail above, in the non-aqueous electrolyte battery according to the present invention , manganese oxide is used as the positive electrode.
The positive electrode material mainly composed of
Range of 0.1 to 30 mol% with respect to manganese in gun oxide
Since it was made to be added and heat treated ,
A complex oxide with an ammonium sulfate salt is formed on the surface of the manganese oxide in the positive electrode material, the manganese oxide is protected by the complex oxide with the ammonium sulfate salt, and a reaction with a nonaqueous electrolytic solution or the like is suppressed. Becomes,
As a result, it becomes possible to obtain a non-aqueous electrolyte battery with less self-discharge and excellent storage stability, and especially when it is used as a secondary battery, its storage stability is significantly improved, and its charge-discharge cycle characteristics are also improved. The non-aqueous electrolyte battery having excellent storage characteristics and charge / discharge cycle characteristics has also been obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an internal structure of a non-aqueous electrolyte battery in each of Examples and Comparative Examples.

[Explanation of symbols]

1 positive electrode 2 Negative electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H01M 10/40 H01M 10/40 Z // C01G 45/02 C01G 45/02 (72) Inventor Toshiyuki Noma Keihan, Moriguchi City, Osaka Prefecture 2-5-5 Hondori Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) Reference JP-A-3-74054 ( JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/36-4/62 H01M 4/00-4/04 C01G 45/00-45/02

Claims (2)

(57) [Claims] 1. A includes a positive electrode, a negative electrode and a nonaqueous electrolyte, the nonaqueous electrolyte battery using the positive electrode material mainly composed of manganese oxide in the positive electrode, as the positive electrode, the manganate
The positive electrode material, which is mainly composed of
Range of 0.1 to 30 mol% with respect to manganese in gangan oxide.
And heat-treat it with ammonium sulfate and manganese
A non-aqueous electrolyte battery using a composite oxide formed with an oxide . 2. In the non-aqueous electrolyte battery according to claim 1,
The positive electrode material mainly composed of the above manganese oxide.
As ammonium sulfate salt to be added, divalent iron, divalent iron
Ammonium sulphate containing either cobalt or aluminum
A non-aqueous electrolyte battery using an um salt.