JP3443217B2 - Non-aqueous electrolyte battery - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a negative electrode containing lithium metal, a lithium alloy, or a carbon material capable of inserting and extracting lithium as an active material of lithium, and a positive electrode containing manganese dioxide as an active material. The present invention relates to a non-aqueous electrolyte battery including a non-aqueous electrolyte solution, and more specifically, to improvement of a positive electrode material.

[0002]

2. Description of the Related Art A lithium battery using lithium as a negative electrode active material has advantages such as high voltage, high energy density and good storage characteristics, and is widely used as a power source for small electronic devices, fully automatic cameras and the like. ing.

There are three typical types of lithium batteries depending on the positive electrode active material. (1) Manganese dioxide lithium battery using manganese dioxide as the positive electrode active material,
(2) A graphite fluoride lithium battery using fluorinated graphite as the positive electrode active material, and (3) a thionyl chloride lithium battery using thionyl chloride as the positive electrode active material. Among these, in the lithium manganese dioxide battery using manganese dioxide as the positive electrode active material of (1), manganese dioxide as the positive electrode active material is inexpensive,
It is widely used because of its large discharge capacity and the chemically stable positive electrode active material manganese dioxide.

However, the lithium manganese dioxide battery using manganese dioxide as the positive electrode active material has a problem that the discharge capacity is remarkably reduced if it is left as it is after being manufactured. This is because the high voltage of the battery immediately after assembly causes the manganese dioxide, which is the positive electrode active material, to react with the electrolytic solution inside the battery. Therefore, conventionally, a method of suppressing the reaction between manganese dioxide, which is the positive electrode active material, and the electrolytic solution by discharging the battery to some extent (pre-discharge) immediately after assembly to lower the voltage of the battery has been adopted. It was However, such preliminary discharge not only wastes the original discharge capacity of the battery but also increases the manufacturing cost of the battery.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and it eliminates the need for pre-discharge after assembly of a non-aqueous electrolyte battery using manganese dioxide as a positive electrode active material. It is intended to increase the capacity and reduce the manufacturing cost.

[0006]

The present invention provides a non-aqueous electrolyte battery comprising a negative electrode using lithium as an active material, a positive electrode using manganese dioxide as an active material, and a non-aqueous electrolyte. The main materials of the positive electrode are boron oxide and manganese dioxide
After being mixed and heat-treated , and the atomic ratio B / Mn of boron and manganese in the main material is B / Mn.
Is in the range of 0.01 to 0.1.

It is preferable that the main material of the positive electrode is a mixture of boron oxide and manganese dioxide which has been heat-treated at a temperature range of 150 to 430.degree.

In the battery of the present invention, the solvent is butylene carbonate (BC), ethylene carbonate (EC), dimethoxyethane (DME), propylene carbonate (PC), vinylene carbonate (V).
C), γ-butyrolactone (γ-BL), dimethyl carbonate (DMC), diethyl carbonate (DE
C), methyl ethyl carbonate (MEC), tetrahydrofuran (THF), dioxolane (DOXL),
1,2-diethoxyethane (DEE) and a mixture thereof can be used, and solute is LiCF ₃ S.
O ₃ , LiPF ₆ , LiBF ₄ , LiAsF ₆ and LiC
10 ₄ can be used.

[0009]

When boron oxide and manganese dioxide are mixed and then heat treated, a film of boron oxide is formed on the surface of the manganese dioxide particles. This coating suppresses the chemical activity of manganese dioxide. Therefore, it is considered that the reaction between manganese dioxide and the electrolytic solution is suppressed, and even if the battery is left as it is after being manufactured, the discharge capacity of the battery is not significantly reduced. Note that, due to the formation of this film, boron oxide is unevenly distributed near the surface of the manganese dioxide particles.

Incidentally, as an invention similar to the present invention, Japanese Patent Laid-Open Nos. 2-175886 and 2-25356.
There is one described in Japanese Patent No. 0.

Japanese Patent Laid-Open No. 175886/1990 adopts a method in which boron is contained in an electrolytic bath when synthesizing electrolytic manganese dioxide and is incorporated into manganese dioxide during electrolysis. In this method, since (A) boron is uniformly dispersed in manganese dioxide, the effect of covering the surface of manganese dioxide particles is smaller than that of the present invention. Since it is difficult to increase the content of (B) boron, the surface of the manganese dioxide particles cannot be covered sufficiently as in the present invention. There are two problems.

Japanese Patent Laid-Open No. 2-253560 adopts a method in which boron is mixed with manganese dioxide in the form of boric acid and borate and heat-treated. in this way,
With (a) boric acid, water is released during heat treatment, so that dehydration of manganese dioxide may be insufficient. (If the dehydration of manganese dioxide is insufficient, the characteristics of the battery may deteriorate.) (B) If the dehydration reaction of boric acid (change from boric acid to boron oxide) is not sufficient, unreacted boric acid may remain When the water is released, the storage characteristics of the battery deteriorates. (C) When borate is added and heat treatment is applied, the effect of improving the storage characteristics of the battery is smaller than when boron oxide is added. There are three problems.

If the heat treatment temperature is lower than 150 ° C., the water content in the manganese dioxide cannot be sufficiently removed, and 430
When the temperature exceeds ℃, the capacity of manganese dioxide as a battery active material decreases, so that the temperature range is preferably 150 to 430 ℃.

[0014]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples.

Example 1 A coin-shaped non-aqueous electrolyte battery of the present invention was manufactured.

[Preparation of Positive Electrode] Boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) were used in an atomic ratio B / Mn = 0.0.
After mixing at a ratio of 1 to 375 this mixture in air
It heat-processed at 20 degreeC for 20 hours, and produced the positive electrode main material. This positive electrode main material, carbon black as a conductive material, and fluororesin as a binder were mixed in a weight ratio of 85: 10: 5 to prepare a positive electrode mixture. This positive electrode mixture is pressure-molded into a disk shape to prepare a positive electrode, which is then heated at 250 ° C. in vacuum.
And heat treated for 2 hours.

As a positive electrode collector, a stainless steel plate (SUS
430) was used.

[Preparation of Negative Electrode] Lithium metal was punched into a disk shape to prepare a negative electrode.

As a negative electrode current collector, a stainless steel plate (SUS
430) was used.

[Preparation of Non-Aqueous Electrolyte] 1,2-butylene
Carbonate (BC) and ethylene carbonate (EC)
And 1,2-dimethoxyethane (DME) in a volume ratio of 2
As a solute in a solvent mixed at a ratio of 5:25:50
Lithium trifluoromethanesulfonate (LiCF ₃
SO₃) Is dissolved at a ratio of 1 mol / liter to
An aqueous electrolytic solution was prepared.

[Battery Assembly] The battery A1 of the present invention (battery size: diameter 2) was prepared using the above positive electrode, negative electrode and non-aqueous electrolyte solution.
4 mm; thickness 3 mm) was produced. As the separator, a polypropylene-made microporous thin film having ion permeability was used, and this was impregnated with the above-mentioned non-aqueous electrolyte solution.

FIG. 1 is a cross-sectional view schematically showing the produced battery A1 of the present invention. The battery A1 of the present invention shown in FIG. 1 includes a positive electrode 1, a negative electrode 2, a separator 3 for separating these two electrodes, and a positive electrode can 4. , A negative electrode can 5, a positive electrode current collector 6, a negative electrode current collector 7, a polypropylene gasket 8, and the like. The positive electrode 1 and the negative electrode 2 face each other via the separator 3 impregnated with the non-aqueous electrolyte solution and are housed in the battery case formed by the positive electrode can 4 and the negative electrode can 5.
The negative electrode 2 is connected to the positive electrode can 4 via the negative electrode current collector 7 and the negative electrode 2 is connected to the negative electrode can 5 via the negative electrode current collector 7. It can be taken out as energy.

[Example 2] The present invention was carried out except that boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) were mixed at an atomic ratio B / Mn = 0.03 in the preparation of the positive electrode. Inventive battery A2 was produced in the same manner as battery A1.

[Example 3] In the present invention, except that boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) were mixed at an atomic ratio B / Mn = 0.05 in the production of the positive electrode. Inventive battery A3 was produced in the same manner as battery A1.

[Example 4] The present invention was carried out except that boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) were mixed in an atomic ratio B / Mn = 0.1 in the production of the positive electrode. A battery A4 of the invention was produced in the same manner as the battery A1.

Comparative Example 1 A comparative battery B1 was prepared in the same manner as the battery A1 of the present invention, except that boron oxide (B ₂ O ₃ ) was not added in the preparation of the positive electrode.

[Comparative Example 2] The present invention was carried out except that boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) were mixed in an atomic ratio B / Mn = 0.15 in the preparation of the positive electrode. Comparative battery B2 was made in the same manner as battery A1.

[Comparative Example 3] In the production of a positive electrode, boric acid (H ₃ BO ₃ ) was used in place of boron oxide (B ₂ O ₃ ) and manganese dioxide (MnO ₂ ) in an atomic ratio B / Mn = 0.1. Comparative battery B3 was made in the same manner as battery A1 of the invention, except that the mixture was mixed at the ratio of.

[Comparative Example 4] In preparation of a positive electrode, lithium tetraborate (Li ₂ B ₄ ) was used instead of boron oxide (B ₂ O ₃ ).
O ₇ ) and manganese dioxide (MnO ₂ ) in atomic ratio B / Mn
Comparative battery B4 was made in the same manner as battery A1 of the invention, except that the mixture was mixed at a ratio of 0.1.

[Measurement of Discharge Capacity after Storage of Battery] The batteries of the present invention (A1 to A4) and comparative batteries (B1 to B4)
Was stored at 60 ° C. for 20 days, and the discharge capacity was measured.

Only the comparative battery B1a has an appropriate amount (15 mA).
h), pre-discharged and stored. (Comparative battery B1
The battery which is not pre-discharged is the comparative battery B1b), and the discharge capacity is the discharge amount when discharged to a final voltage of 2 V with a resistance of 5.6 kΩ.

The discharge capacity measurement results are shown in Table 1.

[0033]

[Table 1]

The following can be seen from Table 1.

First, looking at the effect of addition depending on the type of boron compound when the same amount of boron added, that is, when the atomic ratio B / Mn of boron and manganese is 0.1, boron oxide (B ₂ O _The battery A4 of the present invention to which ₃ ) is added is boric acid (H
₃ BO ₃ ) -added comparative battery B3 and lithium tetraborate (Li ₂ B ₄ O ₇ ) -added comparative battery B4 had a higher discharge capacity, and the addition of the boron compound was It can be seen that the form of boron oxide in the present invention is the best.

Considering the cause of this, boric acid (H
_In the comparative battery B3 to which ₃ BO ₃ ) was added, water was released from boric acid during the heat treatment, resulting in insufficient water removal of manganese dioxide, and part of boric acid remained unreacted. It is considered that water is released from boric acid after the heat treatment. On the other hand, in the comparative battery B4 to which lithium tetraborate (Li ₂ B ₄ O ₇ ) was added, lithium tetraborate was more effective in covering the surface of the manganese dioxide particles than the boron oxide used in the battery of the present invention. It can be small.

Next, comparative battery B1 containing no boron compound
And the comparison between the present invention batteries A1 to A4.

First, looking at the effect of the addition of boron oxide (B ₂ O ₃ ) in the case of not performing the preliminary discharge which causes an increase in the manufacturing cost, the batteries A1 to A4 (atoms of the present invention) to which boron oxide is added are examined. Ratio B / Mn = 0.01-0.1)
Indicates that the discharge capacity is higher than that of the comparative battery B1b to which the boron compound is not added. However,
If the amount of boron oxide added is increased too much, the content of manganese dioxide, which is the active material, will decrease only by the addition of boron oxide. That is, the atomic ratio of boron to manganese B / Mn
In Comparative Battery B2 in which the amount of boron oxide added was increased to 0.15, the discharge capacity was lower than that of Comparative Battery B1b in which no boron compound was added. Therefore, in the case of reducing the manufacturing cost of the battery except for the preliminary discharge step, the addition amount of boron oxide is an atomic ratio B / Mn of boron and manganese of 0.01 to 0.01 in the batteries A1 to A4 of the present invention.
It must be within the range of 0.1.

Next, in order to increase the discharge capacity, the comparative battery B1a which has been subjected to the conventional pre-discharge and the above-mentioned book which has not been subjected to the pre-discharge are added to the battery to which the boron compound is not added. Comparing with the invention battery, the invention batteries A1 to A3 (atomic ratio B / Mn = 0.01 to 0.05)
It can be seen that the discharge capacity is increased due to the addition of boron oxide even though the preliminary discharge is not performed. That is, the addition amount of boron oxide added to the positive electrode is 0.01 to 0.05 in the batteries A1 to A3 of the present invention with the atomic ratio B / Mn of boron and manganese.
The pre-discharge step can be omitted, which can reduce the manufacturing cost, and at the same time, can increase the discharge capacity as compared with the case of performing the conventional pre-discharge.

The batteries A1 to A3 of the present invention to which boron oxide (B ₂ O ₃ ) was added (atomic ratio B / Mn = 0.01 to 0.
05), the discharge capacity is particularly high in the present invention batteries A1 and A2 (atomic ratio B / Mn = 0.01 to 0.0).
3).

Therefore, the amount of boron oxide (B ₂ O ₃ ) added is such that the atomic ratio B / Mn of boron and manganese is 0.01.
Must be in the range of 0.1, preferably 0.01
To 0.05, more preferably 0.01 to
It is in the range of 0.03.

[0042]

The non-aqueous electrolyte battery of the present invention exhibits excellent storage characteristics even without preliminary discharge. Therefore, the pre-discharge step which has been conventionally performed can be omitted. Therefore, the original discharge capacity of the battery can be fully utilized, and the manufacturing cost can be reduced. As a result, it is possible to provide a high-capacity, inexpensive non-aqueous electrolyte battery containing manganese dioxide as a positive electrode active material.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a battery of the present invention manufactured in a coin shape.

[Explanation of symbols]

1 ... 2 ... Negative electrode 3 ... Separator 4 ... Positive electrode can 5 ... Negative electrode can 6 ... Positive electrode current collector 7 ... Negative electrode current collector 8 ... Gasket

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Yamamoto 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) Reference JP-A-2-253560 (JP, A) JP Flat 6-333576 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/00-4/62

Claims (3)

(57) [Claims] 1. A non-aqueous electrolyte battery comprising a negative electrode using lithium as an active material, a positive electrode using manganese dioxide as an active material, and a non-aqueous electrolyte, wherein the main material of the positive electrode is boron oxide. And manganese dioxide are mixed together and then heat treated , and the atomic ratio B / Mn of boron and manganese in the main material is in the range of 0.01 to 0.1. A non-aqueous electrolyte battery characterized by: 2. The atomic ratio B / Mn is 0.01 to 0.05.
The non-aqueous electrolyte battery according to claim 1, wherein 3. The atomic ratio B / Mn is 0.01 to 0.03.
The non-aqueous electrolyte battery according to claim 1, wherein