JPH0286059A - Manufacture of positive mix for manganese battery - Google Patents

Abstract

PURPOSE:To enhance high rate discharge performance by preparing activated chemical manganese dioxide powder with manganese oxide ore, mixing the manganese dioxide powder with a salt aqueous solution, forming powder, then mixing the powder with conductive material powder and an electrolyte, and molding the mixture. CONSTITUTION:Manganese oxide ore is baked, and the baked product is crushed in powder, then the powder is treated with a mineral acid to obtain activated chemical manganese dioxide powder. The powder is sieved to obtain powder having a mean particle size of 20mum or less. The powder obtained is washed or neutralized, then mixed with an aqueous solution of at least one salt selected from the group of an aluminium salt, gallium salt, and titanium salt. The mixture is dried, and press molded, then crushed to obtain powder. The powder is mixed with conductive material powder and an electrolyte, then the mixture is molded to form a positive mix. A manganese dry battery using this positive mix enhances pulse discharge performance.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for producing a positive electrode mixture for manganese batteries, and more specifically, to a method for suppressing an increase in internal resistance of a battery during discharge. and light load discharge.

The present invention relates to a method for producing a positive electrode mixture that is effective for improving pulse discharge characteristics during medium load discharge.

(Prior Art) A positive electrode mixture for a manganese dry battery is usually prepared by mixing manganese dioxide powder as an active material, conductive material powder, and electrolyte in a predetermined ratio. As manganese dioxide, electrolytic manganese dioxide, chemically synthesized manganese dioxide, natural manganese dioxide, activated chemical manganese dioxide, etc. are used.

Among these manganese dioxides, activated chemical manganese dioxide is said to have heavy-load discharge characteristics similar to those of batteries using electrolytic manganese dioxide as an active material, and is said to have lower manufacturing costs. Because of this, it has attracted wide attention.

This activated chemical manganese dioxide is produced by roasting and pyrolyzing various manganese oxide ores in a controlled atmosphere to produce a roasted product whose main components are manganese sesquioxide and trimanganese tetroxide, and then pulverizing this roasted product. Manganese dioxide is activated by treating the resulting powder with mineral acids such as sulfuric acid, nitric acid, and hydrochloric acid.

(Problems to be Solved by the Invention) However, in a battery in which the activated chemical manganese dioxide is used as an active material and the electrolyte is an electrolytic solution containing zinc chloride as a main component, the five-load discharge characteristics are relatively good; However, during light load discharge or medium load discharge, the internal resistance of the battery increases, resulting in a problem that the pulse discharge characteristics deteriorate. Since this pulse discharge characteristic is an important characteristic in fields such as pagers and remote controls for various audio products, the above-mentioned batteries are not necessarily satisfactory as power sources in these fields.

In order to suppress such an increase in internal resistance, measures have traditionally been taken to increase the amount of electrolyte mixed or the amount of conductive material powder mixed when preparing the positive electrode mixture. ing. However, increasing the amount of electrolyte solution causes frequent leakage of the battery. In addition, increasing the amount of conductive material powder will reduce the amount of activated chemical manganese dioxide powder in the positive electrode mixture, which will result in a decrease in the heavy load discharge characteristics of the battery. .

In general, this activated chemical manganese dioxide powder has a tap density of 1.6 to 2.2 g/cm', which is lower than that of electrolytic manganese dioxide, which is 2.2 to 2.4 g/am', so it maintains the specified discharge characteristics. In order to achieve this, it is necessary to mix a certain amount or more, but carrying out step 1 of increasing the amount of conductive material powder mixed in order to lower the internal resistance is nothing but going against the above problem. .

An object of the present invention is to provide a method for producing a positive electrode mixture that is effective in solving these problems, suppressing an increase in internal resistance of a battery, and thereby preventing a decrease in pulse discharge characteristics.

(Means for Solving the Problems) The method for producing a positive electrode mixture for manganese batteries of the present invention includes roasting manganese oxide ore to obtain a roasted product, then crushing the roasted product to form a powder, and then Process of processing activated chemical manganese dioxide powder with powdered mineral acid (first step): The activated chemical manganese dioxide powder has an average particle size of 2
After washing or neutralizing the powder with a temperature of 0F or less, the obtained treated powder, carbon material powder, and aluminum salt,
Step of mixing with an aqueous solution of at least one salt selected from the group of gallium salts and titanium salts (second step): The mixture obtained in the step is dried and compression molded,
Process of pulverizing the obtained compact into powder (third process)
;and.

A step of mixing the powder obtained in the above step, the conductive material powder, and the electrolytic solution, and then molding the obtained mixture (fourth step)
; It is characterized by comprising the following.

The first step in the production method of the present invention is a step of producing activated chemical manganese dioxide powder from manganese oxide. The ores used include soft manganese ore and rhodochrosite which are produced in various places. Such ore is coarsely ground to a predetermined particle size, and the resulting powder is roasted in a roasting furnace in a controlled atmosphere. It is necessary to change the roasting temperature depending on the type of ore, but it is usually 550 to 1
000℃. In this roasting process, manganese dioxide in the ore is converted to manganese sesquioxide at a temperature of around 400 to 500°C, and further converted to trimanganese tetroxide at a temperature of around 800 to 1000°C. The roasting time is not particularly limited, but is usually about 0.5 to 5 hours.

The roast product thus obtained is further ground into a fine powder, which is then treated with a mineral acid to form an activated chemical manganese dioxide powder.

Examples of the mineral acids used include sulfuric acid, nitric acid, and hydrochloric acid.

Through this treatment, manganese dioxide is produced, as shown in the reaction equation below when sulfuric acid is used as the mineral acid.

Mn20s + HgSO4→MnOs + Mn5O
i + H*0Mn5L + 2H proverb SO+ = M
nO spirit ÷ 2Mn504+ 2HtO The second step is the most distinctive step in the method of the present invention, and is a step for imparting desired properties to the activated chemical manganese dioxide powder obtained in the first step.

In this step, first, the powder obtained in the first step is classified to collect powder having an average particle size of 20 Fm or less. This is because powder having an average particle size larger than 20p has poor particle cohesiveness, which will be described later, and the amount of the powder mixed into a positive electrode mixture decreases, making it difficult to obtain the expected discharge characteristics.

Next, this powder with an average particle size of 20P or less is washed with water or neutralized.The neutralization treatment is carried out in an alkaline aqueous solution such as a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, or an ammonium hydroxide aqueous solution at a predetermined concentration. All you have to do is soak and stir the powder.

By performing such a treatment, the mineral acid remaining on the surface of the powder in the first step is removed.

The obtained treated powder is thoroughly washed with water and then dried, and then this powder, carbon material powder, and an aqueous solution of a salt to be described later are mixed in a predetermined ratio.

The carbon material powder may be any material that has been conventionally used as a conductive material, such as acetylene black and graphite powder.

Examples of the aqueous salt solution include one or a suitable combination of two or more aqueous solutions of salts of metal elements such as aluminum, gallium, and titanium. In particular, an aqueous solution of aluminum salt, which has a high valence, a small ionic radius, and a high hydration number, is effective. Examples of such aluminum salts include aluminum sulfate (Am).
O41s・14~16H, 01, Potash light bread (AlK
(SO41m・12H,O), ammonium light bread (
AJNH4 (SO4)!・12H,01, aluminum chloride fAjcm), aluminum hydroxide IAI fO
Hl, 1, polyaluminum chloride, highly basic aluminum chloride (Ai'-(OH)-Cj ・nHiOl
Also, as a gallium salt,
As gallium chloride, gallium hydroxide, and titanium salts.

Examples include titanium chloride and titanium hydroxide.

The blending ratio of the three is 1g of activated chemical manganese dioxide powder.
On the other hand, it is preferable that the amount of the conductive material powder is 0.15 to 18 g, and the amount of the aqueous salt solution is enough to make the whole into a slurry. It is preferable to set the salt concentration of the aqueous solution and the amount used so that the amount of (for example, aluminum) adsorbed to 1 g of activated chemical manganese dioxide powder is 20 mg or less, and the adsorption amount of the metal element is the above value. This is because, if the amount is more than 1, even if the increase in internal resistance can be suppressed, problems such as a shortened discharge duration and a decrease in the discharge utilization rate of manganese dioxide will occur.

When mixing the three components, the pH of the slurry after mixing should be 3 to 3.
It is preferable to adjust the p value of the slurry to 6, if the p) of the slurry is lower than 3, then 2. For example, if an aqueous solution of aluminum salt is used as the aqueous salt solution, aluminum will not undergo ion exchange on the surface of the activated chemical manganese dioxide. If aluminum hydroxide remains in the solution and the pH is higher than 6, aluminum hydroxide is generated in the slurry and undergoes ion exchange with the hydrogen ions present on the surface of activated chemical manganese dioxide.

In this way, a mixture is obtained in which the activated chemical manganese dioxide powder and the carbon material powder are homogeneously mixed, and a predetermined amount of gold scrap ions such as aluminum ions are adsorbed on the surfaces of both.

The third step is a step of producing powder suitable for preparing a positive electrode mixture from the mixture obtained in the second step.

That is, if there is too much water in the slurry in the second step, filtration treatment is performed, and the resulting cake is heated at a temperature of, for example, 90°C for 20 minutes.
After drying for about an hour, this is molded using a roll press or the like. The resulting compact becomes dense due to the action of the blended carbon material powder, and as a result, the state of mutual contact between the activated chemical manganese dioxide powder and the carbon material powder is improved.

Next, the obtained molded body is crushed and sieved to obtain powder (secondary particles) with a predetermined particle size.6 Usually, the average particle size is 150.
No more than 1 door.

The fourth step is a step of molding the positive electrode mixture.

That is, this is a step of mixing the powder obtained in the third step, the conductive material powder, and the electrolytic solution in a predetermined ratio, and molding the mixture into a predetermined shape.

The conductive material powder and the electrolytic solution may be of any kind as long as they are used in the positive electrode mixture of this type of battery, and are not particularly limited.

Furthermore, the amounts of the conductive material powder and electrolyte are not particularly limited, and may be the same as in the conventional case.

The pressure applied when molding the mixture of the three materials may generally be about 1 to 10 ton/cm''.

The manganese dry battery according to the present invention is manufactured by incorporating the positive electrode mixture thus obtained into a battery according to a conventional method.

(Function) In the case of the positive electrode mixture of the present invention, for example, if aluminum ions are adsorbed on the surface of activated chemical manganese dioxide, the intersection of the potential-pH line of manganese dioxide shifts to the acidic side, and the pH range is wide. A small potential change (-0,
059V/pH), so the pH buffering capacity increases.

In addition, in the mixture obtained through the second step, the adsorption of aluminum ions proceeds simultaneously to both the activated chemical manganese dioxide powder and the carbon material powder, and the aluminum ions are diffused into the activated chemical manganese dioxide powder. Since the powder (secondary particles) obtained by compression molding in the third step has conductive carbon material powder interposed inside this powder, and this carbon material powder and activated chemical manganese dioxide The contact resistance with the powder has been significantly reduced, and as a result, the utilization rate of activated chemical manganese dioxide is much higher than in the past, and it is possible to reduce the internal resistance of the battery.

(Embodiments of the Invention) Example A manganese oxide ore having a MnOx content of 84% by weight was ground into a powder with a particle size of 60 mesh (Tyler sieve) or less.

This powder was roasted in an atmosphere of about 850°C, and a-M
An n*Os powder was obtained. This powder was heated to a concentration of 3 at 90°C.
It was immersed in a sulfuric acid aqueous solution of M for 2 hours. The powder was then taken out, thoroughly washed with water, poured into an aqueous sodium hydroxide solution with a concentration of IM, stirred, and dried at 90° C. for 2 hours. The average particle size of the resulting dry powder was about 1011 m.

This powder 4. 0.0g and graphite powder with an average particle size of about IP.
Further, 20 d of an aqueous solution of ammonium hydroxide containing highly basic aluminum chloride (A 12 g (o H), C° C.) was added thereto. At this time, the aluminum concentration of the aqueous solution was adjusted so that the amount of aluminum was 5 mg per 1 g of activated chemical manganese dioxide powder.

Stir and mix the whole thing, and the pH of the slurry after mixing is 5.5.
An ammonium aqueous solution was added so that

The supernatant liquid of the slurry is removed from the furnace, and the resulting cake is heated to 90°C.
After drying for 2 hours in a roller press machine for 3 t
Compression molding was carried out under a pressure of 100 lb. on/cm". The obtained molded body was pulverized to obtain a powder with a size of 100 mesh (Tyler sieve).

4.2 g of this powder, 0.65 g of acetylene black, and 3.33 g of an electrolyte containing 25% zinc chloride and 2.5% ammonium chloride were mixed, and the resulting mixture was mixed with 3 to
A positive electrode mixture was produced by molding at a pressure of 100 m/cm.

An R6 type manganese dry battery was manufactured by incorporating this positive electrode mixture.

Comparative Example 1 A positive electrode mixture was produced in the same manner as in Example 1, except that the aqueous solution of aluminum salt was not used, and the same <R6 type manganese dry battery was produced using this.

Comparative Example 2 A positive electrode mixture was prepared in the same manner as in Example 1, except that acetylene black was not added to the activated chemical manganese dioxide powder, and the same <R6 type manganese dry battery was manufactured using this.

Comparative Example 3 A positive electrode mixture was produced in the same manner as in Example 1, except that the average particle size of the activated chemical manganese dioxide powder was 25 pm or more, and the same R6 type manganese dry battery was produced using this. .

Discharge duration (minutes) until the terminal voltage reaches 0.9V when discharging the above four types of batteries under a heavy load of 1.5Ω
was measured. The results are shown in the table.

In addition, a load resistor of 1.2 Ω was connected to each battery and continuous discharge was performed, and the change in terminal voltage over time and the change in internal resistance of the battery over time were measured. The results are shown in Figure 16.
In the figure, a solid line represents a change in terminal voltage over time, and a dotted line represents a change in internal resistance over time.

Furthermore, in the process of continuous discharge with a load resistance of 1.2 Ω connected to the battery, the change in terminal voltage of each battery over time was measured when a pulse discharge of 10 Ω for 3 seconds was superimposed once a day. The results are shown in Figure 2.

〔Effect of the invention〕

As is clear from the above explanation, the positive electrode mixture produced by the method of the present invention improves the heavy load discharge characteristics of the manganese dry battery incorporating it, reduces the increase in internal resistance, and improves the pulse discharge characteristics. Its industrial value is great because it improves the

[Brief explanation of the drawing]

Figure 1 shows the changes in terminal voltage and internal resistance over time during continuous discharge of 1.2Ω for each battery, and Figure 2 shows the changes over time in the terminal voltage and internal resistance of each battery at 1.2Ω.
FIG. 2 is a diagram showing the change over time in the terminal voltage of each battery when a pulse discharge of 10 Ω for 3 seconds is superimposed once a day during continuous discharge of 2 Ω. Kawaiyaki Gin I%11(a) - Fig. 1 Chair f4 colors, Ginzo (Japanese) → Fig. 2

Claims (1)

[Claims] A process of roasting manganese oxide ore to produce a roasted product, then pulverizing the roasted product into a powder, and then treating the powder with a mineral acid to produce an activated chemical manganese dioxide powder. ; Of the activated chemical manganese dioxide powder, the average particle size is 2
After washing or neutralizing the powder with a diameter of 0 μm or less, the obtained treated powder, carbon material powder, and at least one selected from the group of aluminum salt, gallium salt, and titanium salt are combined.
a step of mixing the seeds with an aqueous solution of salt; drying the mixture obtained in the step and then compression molding;
A step of pulverizing the obtained molded body into powder; and a step of mixing the powder obtained in the step, the conductive material powder, and the electrolytic solution, and then molding the obtained mixture. A method for producing a positive electrode mixture for manganese batteries, characterized by: