JPH02195647A - Dry cell - Google Patents

Abstract

PURPOSE:To improve the high load discharge capacity and to form a positive electrode compound of good moldability by using anthracene and creosote oil for the material as a conductive agent and carbon black obtained by the furnace method. CONSTITUTION:In a dry cell in which a positive electrode compound made by mixing a conductive agent or the like is mixed to manganese dioxide as an active substance, and applying a pressure to form is housed in a negative electrode zinc can, anthracene, creosote oil, and the like are used for the material as a conductive agent, and carbon black obtained by the furnace method is also used. As the carbon black, the carbon black which has the property to have the mean particle diameter 0.03-0.05mum, and the specific surface area 80-90m<2>/g is preferable. Such a carbon black has the probability of mixing very little impurities, and a large electrolyte holding capacity. As a result, by using such a conductive agent, the electrolyte amount held in the positive electrode compound is increased, and the high load discharge capacity of the dry cell is improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a dry battery that uses specific carbon black as a conductive agent in a positive electrode mixture to improve high-load discharge performance, etc. .

<Conventional technology> In dry batteries, the active material is usually manganese dioxide, which is mixed with a conductive agent, electrolyte, etc., and then pressure-formed to form a positive electrode mixture, which is then stored in a zinc can that serves as the negative electrode. The following configuration has been adopted.

The above-mentioned conductive agent is required to have functions such as not only good conductivity, but also a large electrolyte retention capacity, and a strong chain structure between particles and high stracture properties. .

Conventionally, such conductive agents include, for example, natural graphite, by-product carbon obtained from a Texaco furnace, acetylene black, or a mixture of Chinese and German materials.

Among these conductive agents, natural graphite, by-product carbon, etc.
Although it is inexpensive, it contains impurities such as heavy metals such as iron, copper, and nickel, so when it is used as a conductive agent in the positive electrode mixture, it has the disadvantage of causing side reactions and deteriorating battery performance.

On the other hand, the acetylene black mentioned above has high purity and good physical properties, so if it is used as a conductive agent in the positive electrode mixture, fairly good battery characteristics can be obtained.
It is currently used as a conductive agent in most dry batteries.

<Problems to be Solved by the Invention> However, this type of dry battery is inferior to, for example, an alkaline battery in discharge performance, particularly in high-load discharge characteristics, and there is a strong desire to improve its performance.

In order to improve such performance, the ability of the positive electrode mixture to absorb the electrolyte becomes important, and therefore, the conductive agent used in the positive electrode mixture is also desired to have a higher ability to retain the electrolyte.

In addition, from the viewpoint of stabilizing the formulation of the positive electrode mixture and stabilizing the moldability, a conductive agent with a stronger chain structure and higher structure is desired.

Means for Solving Problems〉 The present inventor has solved the problem by changing operating conditions such as temperature and pressure.
Focusing on the furnace method, which allows the particle size, specific surface area, and structurability of the obtained carbon black to be controlled to a certain degree, carbon blacks with various particle sizes and specific surface areas obtained by this furnace method are used. A comparative study of carbon black as a conductive agent for dry batteries revealed that carbon black produced by this furnace method from specific raw materials has a high electrolyte retention property, and is also good for filling molds and pressure molding. He discovered this and completed this invention.

That is, the dry battery of the present invention is a dry battery in which a positive electrode mixture prepared by mixing manganese dioxide as an active material with a conductive agent and the like and press-molding the mixture is housed in a negative electrode zinc can, in which the conductive agent is anthracene or the like. The gist is to use carbon black obtained by a furnace method using creosote oil or the like as a raw material.

Specifically, the above-mentioned carbon black preferably has an average particle diameter of 0.03 to 0.05 μm and a specific surface area of 80 to 30 ryl'/g.
When this is used, a significant improvement in battery characteristics can be expected.

The above-mentioned carbon black has extremely low possibility of contamination with impurities, and its ability to retain electrolyte is greater than that of conventional acetylene black. Therefore, if it is used as a conductive agent, it will improve the positive electrode composition. The amount of electrolyte retained in the agent is increased, and as a result, the high load discharge performance of the dry battery is improved.

Moreover, this carbon black has much better filling properties into a mold and pressure moldability than conventional carbon blacks such as acetylene black, and can produce a positive electrode mixture with good moldability.

Furthermore, this carbon black has a very regular crystal structure, and the chain structure between the particles is strong, resulting in strong structure (high structure). Therefore, compared to conventional acetylene black, it is physically stronger and less likely to break, and has the advantage of being able to be sufficiently stirred when mixing the positive electrode mixture, improving the uniformity of the mixture and improving battery performance. Variations are suppressed.

<Example> This invention will be explained in detail below.

It is obtained by the furnace method using anthracene and creosote oil as raw materials, and the particle size (μ
m) and specific surface area (m2/g) (Mitsubishi conductive carbon black manufactured by Mitsubishi Chemical Corporation), the mixing weight ratio of the active material manganese dioxide and these acetylene blacks was 7:1. Then, to this mixed powder, add zinc chloride-based electrolyte solution with a weight ratio of water: zinc chloride: ammonium chloride of 100:35:5 in the amount shown in Table 1, and then knead them. The material was then pressure-molded into a cylindrical shape to create various positive electrode mixtures. These positive electrode mixtures are placed in a negative electrode zinc can via a paper separator etc. that is tightly attached to the inner surface of the zinc can, and a carbon rod that will become a positive electrode current collector is then driven into the center of this positive electrode mixture. I made R6P type dry batteries.

In addition, conventional acetylene black (particle size 0.03-0
．． A similar dry cell (conventional product) was prepared, except that 04μI, specific surface area 60I/g) was used as the conductive agent of the positive electrode mixture.

Table 1 These dry batteries have a discharge resistance of 5Ω and a final voltage of 0.
up to 9V and a final voltage of 0.85V with a discharge resistance of 1OΩ
The discharge time of each dry battery was measured. In addition, the moldability of the positive electrode mixture used in each dry battery was examined.

These results are shown in Table 1 as the average value of five samples each.

Further, in Table 1, the numerical values for each discharge test are indexes when each discharge time in a conventional product in which the amount of electrolyte in the positive electrode mixture is 38% by weight is set as 100. In addition, the moldability of the mixture is the result of visually observing the condition when each mixture was placed in a mold and pressure-molded into a cylindrical shape, then removed from the mold and observed. In the table, double circles indicate Juumaru means "good" and means that there is no chipping at all and the filling properties are good.
This means that there is not much difference compared to when conventional acetylene black is used. Also, triangles are “slightly bad”
"X" means bad, and unless the moldability is 9 or higher, it cannot be used as a product.

From this result, the particle size is 0.03 to 0.05μ.
When the carbon black of the present invention having a specific surface area of 80 to 30 rd"/g is used, the battery performance, especially the high load discharge performance, is excellent, and the mixture moldability is good, so this range is suitable for this type of dry battery. It can be seen that the value is suitable for use as a conductive agent.

<Effects of the Invention> As described above, according to the present invention, by using the above-mentioned specific carbon black, high load discharge performance can be improved, and at the same time, a positive electrode mixture with good moldability can be produced. be effective.

Patent applicant: Fuji Electrochemical Co., Ltd. person Tail Crotch light male

Claims (1)

[Scope of Claims] 1. In a dry cell using a positive electrode mixture formed by mixing manganese dioxide as an active material with a conductive agent and press-molding the mixture, the conductive agent is made of anthracene and creosote oil as raw materials, and a furnace is used. A dry battery characterized by using carbon black obtained by the method. 2. The average particle size of the carbon black is 0.03 to 0.
The dry battery according to claim 1, wherein the dry battery has a thickness of 0.05 μm. 3. The specific surface area of the carbon black is 80 to 30 m^
2/g. 2/g.