JPH0636767A - Nonaqueous electrolyte battery and manufacture of its active material - Google Patents

Abstract

PURPOSE:To uniformly disperse a carbon material on the surface of manganese dioxide grains for a sufficient electrode reaction by mixing and dispersing manganese dioxide and the carbon material with a vapor phase dispersing mixer. CONSTITUTION:Manganese dioxide 1 and carbon black 2 serving as a carbon material are mixed it the ratio of 1wt.% for the carbon material against the manganese dioxide weight, the mixture is put into a vapor phase dispersing mixer rotated at the revolving speed of 1,500r.p.m., and the mixer is operated for 3min. The carbon material of 3wt.% against the manganese dioxide weight is added, the mixture is put into a separate vapor phase dispersing mixer capable of being rotated at a high speed, and the mixer is operated at the revolving speed of 6,000r.p.m. for 2min to obtain manganese dioxide with carbon black for a positive electrode mix. When a manganese dioxide-lithium battery is constituted with this positive electrode mix, the initial impedance characteristic can be improved, the battery characteristic is stabilized, and the high-load discharge characteristic can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-aqueous electrolyte battery and its active material, and more particularly to a method for producing a positive electrode active material composed of a metal oxide such as manganese dioxide and a carbon material.

[0002]

2. Description of the Related Art Conventionally, a battery using a mixture of a metal oxide such as manganese dioxide and a carbon material as one active material, for example, a lithium battery containing manganese dioxide as a main active material, uses a carbon material powder as a conductive agent. Further, a fluorocarbon resin is mixed as a binder to form a positive electrode mixture.

The reason why the conductive material is necessary is that manganese dioxide alone has a very low specific conductivity on the order of 10 ⁻⁴ to 10 ⁻³ s / cm. Therefore, in order to impart electronic conductivity to individual manganese dioxide particles to promote a sufficient reduction reaction, the non-conductivity of the positive electrode mixture should be 10 ⁰ to 10 ¹ s / cm.
The order is preferably, and for this reason, fine powder of carbon material is often used as the conductive material. Conventionally, a method of simply adding water to manganese dioxide powder and carbonaceous material powder to form a slurry and mixing and stirring with a mixer to prepare a positive electrode mixture, or as described in JP-A-61-214362, A method has been proposed in which graphite particles, which are one of the conductive materials, are charged with opposite positive charges, and a graphite layer is formed on the surface of the manganese dioxide particles by an electrostatic adsorption effect to form a positive electrode mixture.

[0004]

However, with such a conventional structure, it is difficult to uniformly disperse two different kinds of powders by simply mixing them. In this case, the manganese dioxide powder and Sufficient mutual contact cannot be obtained between carbon powders. When the contact frequency is reduced, there is a problem that the formation of electron conduction network is reduced, a large amount of manganese dioxide that does not participate in the electrochemical reduction reaction remains, and the utilization rate of manganese dioxide in the electrode as a whole is reduced.

The main reason why sufficient contact cannot be obtained between the manganese dioxide particles and the carbonaceous material particles is that the carbonaceous materials are aggregated to form secondary particles. This is because, in the conventional mixing method by merely mechanical stirring, the frequency of collisions and contact between particles is low due to the low mixing rotation speed and the point of rotational orientation. This is due to the fact that the charge adsorption function is impaired and the dispersibility is reduced.

The present invention solves such a problem, and found a manufacturing method capable of uniformly dispersing a carbon material on the surface of manganese dioxide particles to build an appropriate conduction network, and found a non-aqueous electrolyte solution. The purpose is to sufficiently perform the electrode reaction of the battery.

[0007]

Specifically, the problem is solved by mixing and dispersing manganese dioxide and a carbon material in a gas phase dispersion mixer. Specifically, the carbon material is firmly and uniformly fixed on the surface of manganese dioxide by mixing and dispersing under the condition that the rotation speed in the first gas phase dispersion mixer is slower than that in the second gas phase dispersion mixer. Is something that can be done.

[0008]

With this structure, the manganese dioxide particles 1 and the carbon material particles 2 are favorably fixed as shown in the model diagram of FIG. When the specific conductivity of such a positive electrode manganese dioxide is measured in a dry state in an inert atmosphere, it shows a value of 10 ¹ s / cm or more.

[0009]

EXAMPLES An example of the present invention will be described below.

First, manganese dioxide and carbon black, which is a carbon material, are added to the weight ratio of manganese dioxide to 1 carbon material.
Mix in the ratio of wt%, put into a mixer for gas phase dispersion rotating at 1500 rpm, run for 3 minutes, then add carbon material to the weight of manganese dioxide to be 3% by weight. Then, this is put into another mixer for gas phase dispersion capable of high speed rotation, and mixed at a rotation speed of 6000 rpm for 2 minutes,
As a positive electrode mixture, manganese dioxide with carbon black was obtained.

Next, 100 positive electrode manganese dioxide lithium batteries (CR123A) each having a size of 2/3 A were constructed by using this positive electrode mixture, and the AC impedance at 1 kHz was measured to be 0.2 to 0.3Ω. The impedance of the battery using the positive electrode mixture obtained by the conventional technique described above is 0.8 to 1.2Ω, and it is possible to significantly improve the initial impedance characteristics of the battery. FIG. 2 shows the result of conducting a 1 A constant current continuous discharge test on this lithium battery. In the figure, A indicates the product of the present invention, and B indicates the product obtained by the conventional technique. As can be seen from Fig. 2, both the discharge voltage and the utilization rate are increasing. Although carbon black was used as the carbon material in this example, similar results can be obtained by using an amorphous carbon material such as soot, charcoal, pitch, petroleum coke, or graphite in addition to carbon black. The inventors have found out through experiments. Further, when the rotation speed in the first mixing step was set higher than that in the second mixing step, there was no effect at all and the result was comparable to that of the conventional product.

This is because the positive electrode mixture obtained in the present invention is first mixed at a low rotational speed in a high-speed air stream to uniformly fix the carbon material on the manganese dioxide particles. Then, this is again dispersed in the gas phase by further adding a carbon material and dispersing.
By rotating at a high speed of 000 rpm, the powders undergo strong collision and contact friction with each other, and the carbon materials that are regularly arranged on the surface of the manganese dioxide particles are added to the surface by the added carbon particles. As a result, it is firmly driven into an island shape and fixed. The manganese dioxide with carbon material obtained in this way does not easily peel carbon even when an external force is applied, such as when mechanically molding pellets, which is the positive electrode mixture of coin-type lithium batteries. Alternatively, an electrode plate is manufactured by applying a positive electrode mixture to a core made of a metal porous body while pressing it with a roller, and the electrode plate is spirally wound with the other active material and a separator to form an electrode. By applying it to a non-aqueous electrolyte battery provided with a spirally-wound electrode made up of the steps of forming a group, stabilization of battery characteristics and improvement of heavy load discharge characteristics can be obtained.

[0013]

INDUSTRIAL APPLICABILITY As described above, in the method for producing a non-aqueous electrolyte battery and an active material thereof according to the present invention, when the carbon material is on the manganese dioxide particles, the rotation speed of the second mixing step is faster than that of the first mixing step. By doing so, it is uniformly fixed in an island shape, the formation of a network of electron conduction is enhanced, the utilization rate of manganese dioxide as a battery electrode can be enhanced, and a battery with excellent performance can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a model of a positive electrode mixture of the present invention.

FIG. 2 is a comparison diagram of discharge characteristics of the battery of the present invention and a comparative battery.

[Explanation of symbols]

 1 Manganese dioxide 2 Carbon black

Claims (3)

[Claims] 1. A first mixing step in which an active material and a carbon material as a conductive material are mixed in advance by a gas phase dispersion mixer, and a second mixing step in which a carbon material is further added and mixed by a gas phase dispersion mixer. A method for producing an active material for a non-aqueous electrolyte battery, which comprises mixing and dispersing an active material and a conductive material according to. 2. The method for producing an active material for a non-aqueous electrolyte battery according to claim 1, wherein the number of rotations in the first mixing step is slower than the number of rotations in the second mixing step. 3. A non-aqueous electrolyte battery comprising a positive electrode containing manganese dioxide as an active material, a negative electrode containing lithium or an alloy mainly containing lithium as an active material, and a non-aqueous electrolyte solution. In advance, the active material and the conductive material are mixed by the first mixing step of mixing the carbon material which is the conductive material with the gas phase dispersion mixer, and the second mixing step of further adding the carbon material and mixing with the gas phase dispersion mixer. A non-aqueous electrolyte battery using a positive electrode mixture that is mixed and processed into a predetermined form.