JPH01307159A - Nonaqueous solvent battery - Google Patents

Abstract

PURPOSE:To increase heavy load discharge performance by containing a positive active material comprising beta-MnO2 obtained by oxidizing gamma-MnOOH at high temperature and a conductive material comprising oil furnace black in a positive electrode. CONSTITUTION:beta-MnO2 obtained by oxidizing gamma-MnOOH at high temperature is used as a positive active material. Liquid hydrocarbon is partially oxidized in a furnace in the existence of molecular-state oxygen and steam, and by- product carbon produced together with synthetic gas is dried, then heated to obtain oil furnace black having a specific surface area of 90-150m<2>/g. This oil furnace black is used as a positive conductive material. Conductivity and electrolyte retaining capability in a positive electrode are increased, and heavy load discharge performance of a battery is also increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a non-aqueous solvent battery, and more particularly to a non-aqueous solvent battery with excellent heavy load discharge performance.

(Prior art) Nonaqueous solvent batteries using light metals such as Li, Na, and Aβ as negative electrode active materials have high energy density, excellent storage characteristics, and a wide operating temperature range, and are used in calculators, watches, It is often used as a backup power source for memory, but recently there has been a particular demand for heavy load discharge performance. In such a nonaqueous solvent battery, negative electrode active materials such as Li and Na
The selection of the cathode active material in combination with light metals, such as metals, is a very important issue because it determines a large part of the performance of the battery.

Many positive electrode active materials have been studied in the past, but among them, manganese dioxide (MnO□) has shown relatively good layered performance.
It has been widely used because it has the advantage of being chemically stable. In particular, among manganese dioxides, electrolytic manganese dioxide (EMD), which is obtained by electrolytically oxidizing manganese sulfate, is generally used for non-aqueous batteries. It is used.

When using this END in an organic solvent battery, since the crystal structure of EMD is γ type, for example, when lithium is used as the negative electrode active material, the lithium ions do not diffuse smoothly in the M n 02 crystal, resulting in discharging. Capacity decreases. Furthermore, since the γ type contains a large amount of bound water, this bound water reacts violently with the negative electrode active material, causing corrosion and leakage of the battery container. For this reason, a heat treatment is performed at a high temperature of 350 to 450° C. for a long time to transform the crystal structure to the β type and to remove bound water.

In addition to the method described above, a method of thermally decomposing manganese nitrate [Mn (No 3)-.6H201 is known as a method for producing β-MnO2.

On the other hand, the positive electrode of a non-aqueous solvent battery is made by adding and mixing a conductive material and a binder to the above-mentioned active material, and molding this mixture according to the type of battery. Examples of conductive materials used in this case include acetylene black and graphite.

(Problem to be solved by the invention) However, as mentioned above, heavy load discharge performance is currently required, and this requires conventional electrolytic manganese dioxide,
It is no longer possible to use it in combination with acetylene black or graphite.

That is, in order to improve heavy load discharge performance using EMD, it is necessary to consider conductive materials. Acetylene black, which has been conventionally used, has excellent liquid absorption properties but poor conductivity, while graphite has excellent conductivity but poor liquid absorption properties. Therefore, when these are used as conductive materials in the positive electrode of a non-aqueous battery, the liquid retention or conductivity of the positive electrode mixture decreases, making it difficult to lower the battery's internal resistance (<, to improve discharge performance). The same holds true even when a mixture of both is used.

Furthermore, the EMD described above cannot necessarily be said to have sufficient properties as an active material for non-aqueous batteries, and the manufacturing process includes electrolysis as described above, and the electrolysis requires a long time and a large amount of ( There is a problem in that the manufacturing cost is high because of the power consumption.

Moreover, as mentioned above, EMD has a γ-type crystal structure, so in order to change it to a β-type, 350 to 450
When heat treated at ℃, β-MnO□ is produced due to the high temperature.
is further decomposed to produce a lower oxide such as MnaOs, and if this is used as a positive electrode active material, there is a risk of capacity deterioration. Also, Mn (No −) 2′ 6
Also in the method of thermally decomposing H*O, M n 20 s
Mn (NOs)2
- 6H*O has the problem of being difficult and expensive to produce in large quantities.

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a non-aqueous solvent battery with excellent heavy load discharge performance.

[Structure of the Invention] (Means for Solving the Problems) The nonaqueous solvent battery of the present invention uses β-MnO2 obtained by high-temperature oxidation treatment of γ-MnOOH as a positive electrode active material, and also uses liquid hydrocarbon An oil furnace with a specific surface area of 90 to 150 rn''/g obtained by subjecting it to a partial oxidation reaction in the presence of molecular oxygen and water vapor in a furnace, drying the by-product carbon produced at the same time as synthesis gas production, and then heat-treating it. It is characterized by using black as the positive electrode conductive material.

Here, the specific surface area is determined by the BET method, and the same applies to the following description.

The battery of the present invention is characterized in that the positive electrode active material is the above β-MnOz and the positive electrode conductive material is the above oil furnace black, and other elements may be the same as conventional nonaqueous solvent batteries.

The detailed method for producing β-MnO□ used in the present invention is as follows.

The M n OOH used in the present invention is of the γ type, and there are also α and β types, but among these, γ-MnOOH is the only compound that shows a clear X-ray diffraction pattern. γ-Mn
OOH is a black solid with a specific gravity of 3.26, the crystal is monoclinic, a = 8.86, b = 5.24, c = 5.70, the unit cell is Mn a Os (OH) a. be.

If the temperature in the high-temperature oxidation treatment of γ-MnOOH is too high, lower oxides such as M n t O* will be generated, and if the temperature is too low, β-M n Ox will not be generated. in the range of 350°C, more preferably 250°C
It is desirable to perform high-temperature oxidation treatment at around ℃.

The atmosphere for high-temperature oxidation treatment is M
Since lower oxides such as n x O3 may be generated, it is desirable to create an atmosphere containing 20% or more of oxygen. Appropriate treatment time is about 2 to 8 hours under the above conditions.

Further, the detailed method for producing the oil furnace black used in the present invention is as follows.

First, the liquid hydrocarbon used as a raw material has a carbon atom/hydrogen atom weight ratio of 9 or more. Examples of such liquid hydrocarbon include naphtha pyrolysis oil (ethylene heavy end), aromatic hydrocarbons, etc. Examples include liquid hydrocarbons (carbon oil) in which carbon is mixed with carbon, mixed oils in which aromatic liquid hydrocarbons are mixed with C heavy oil, and the like.

Such liquid hydrocarbons are partially oxidized in the presence of molecular oxygen and water vapor in a furnace to generate synthesis gas, and the carbon by-produced at this time is used, but in order to obtain the desired carbon, For 1 ton of liquid hydrocarbon, steam is 200-800kg, preferably 400-800kg
Use g.

The temperature inside the furnace is 1200-1450°C, preferably 130°C
The temperature is 0 to 1450°C, and the pressure during the reaction is 10 to 80 atm, preferably 25 to 80 atm. Note that molecular oxygen is supplied as a gas.

Next, this by-product carbon is heated to 300 to 90% under nitrogen atmosphere.
The product obtained by drying at 0°C for 0.5 to 3 hours and further heating treatment at 1000 to 3000°C for 0.5 to 5 hours in an inert gas atmosphere is the desired oil furnace. It is black. Here, the heat treatment is performed to remove functional groups on the surface of the oil furnace black particles.

The oil furnace black thus obtained preferably has a specific surface area of 90 to 150 rn'/g. If the specific surface area is less than 90 ri''/g, the liquid retention property will be reduced, resulting in a reduction in discharge performance.

Further, if the oil furnace black is larger than 150 rn'/g and used in a battery, manganese dioxide is reduced, leading to capacity deterioration.

Also, this oil furnace black is JISK 14
It is preferable that the amount of hydrochloric acid absorbed by No. 69 is 20 m 115 g or more.

The positive electrode of the battery of the present invention contains the above-mentioned chemically synthesized manganese dioxide and oil furnace black together with a binder at 80% to 80%
It consists of a positive electrode mixture obtained by mixing at a weight ratio of 94:5 to 15:1 to 5 and molding into pellets or the like. Examples of the binder used at this time include polytetrafluoroethylene, polyacrylic acid, and salts thereof.

A light metal is used as an active material in the negative electrode. Here, light metals refer to metals with low specific gravity such as alkali metals and alkaline earth metals, such as lithium, sodium, potassium, calcium, magnesium, and aluminum. Preferably lithium and aluminum are used.

As the electrolyte, an electrolyte such as lithium perchlorate, lithium borofluoride, lithium chloride, etc. is added to a non-aqueous organic solvent such as propylene carbonate, 1,2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, or dioxolane.
A solution dissolved at a concentration of 0.2 to 1.5 mol/I2 is used.

(Function) In the battery of the present invention, the oil furnace black that is the conductive material of the positive electrode has carbon black particles connected in a chain structure, and the surface of the particles is graphitized in a thin layer.
Since the inside has a hollow pore structure, its specific surface area is large and it has excellent liquid absorption properties, and the particle surface has a higher degree of graphitization than acetylene black, so it has excellent conductivity. Furthermore, since there are few functional groups on the particle surface, deterioration of the positive electrode active material can be prevented.

(Embodiment of the Invention) Hereinafter, an embodiment in which the present invention is applied to a coin-shaped non-aqueous solvent battery will be described based on the drawings.

Example In addition to the β-M n O It was molded into a pellet shape with a length of 17 mm and a weight of 0.69 g to prepare a positive electrode mixture.

Next, the positive electrode mixture 2 described above is filled into a positive electrode container 1 made of stainless steel, and on top of the positive electrode mixture 2, a mixed solvent of propylene carbonate and 1°2-dimethoxyethane (volume ratio of 1:1) made of a polypropylene nonwoven fabric is mixed with perchloric acid. A power generation element was constructed by placing a separator 3 impregnated with an electrolytic solution in which lithium was dissolved at a concentration of 1 mol/a, and further placing metal lithium 4 as a negative electrode thereon.

Then, a smart plate 6 made of stainless steel, which also serves as a negative electrode terminal, was provided at the opening of the positive electrode container 1 via a backing 5, thereby sealing the positive electrode mixture 2, the separator 3, and the metal lithium 4 in the battery container.

Then, a coin non-aqueous solvent battery with an outer diameter of 20 mm and a thickness of 2.4 mm as shown in the figure was manufactured.

Twenty manufactured batteries were stored for 30 days, and then the discharge duration (discharge end voltage 2.OV) when a 300Ω load was applied was measured. The results are shown in the table as average values.

Comparative example EMD heated at 400°C for 8 hours was used as an active material.
A coin-shaped nonaqueous solvent battery was assembled in the same manner as in the example except that graphite was used as the conductive material, stored under the same conditions as in the example, and the discharge duration was measured. The results are also listed in the table.

Table [Effects of the Invention] According to the present invention, the positive electrode has excellent conductivity and liquid retention,
A non-aqueous solvent battery with excellent heavy load discharge performance can be provided.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of a coin-type non-aqueous solvent battery that is an embodiment of the present invention. l...Positive electrode container 2...Positive electrode mixture

Claims (1)

[Scope of Claims] A non-aqueous battery having a negative electrode whose active material is a light metal, a non-aqueous electrolyte, and a positive electrode made of an active material and a conductive material, wherein the positive electrode is obtained by high-temperature oxidation treatment of γ-MnOOH. A non-aqueous solvent battery comprising a positive electrode active material made of β-MnO_2 and a positive electrode conductive material made of oil furnace black having a specific surface area of 90 to 15 Om^2/g.