JP2001307745A - Alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve discharge characteristic in a heavy-load region more efficiently. SOLUTION: This battery is equipped with a cathode, an anode and an alkaline electrolyte, and sets the ratio WA/WC, of the anode solid component amount WA to the cathode solid component amount WC, within the range between 0.35 and 0.41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a positive electrode, a negative electrode,
More particularly, the present invention relates to an alkaline battery having more efficiently improved discharge characteristics in a heavy load region.

[0002]

2. Description of the Related Art With the spread of portable electronic equipment in recent years, the demand for cylindrical alkaline batteries has been increasing. At the same time, with the digitization of electronic devices and improvements in compression technology, the amount of power consumption is also increasing. In response to these, a heavy load area of the alkaline dry battery, for example, 1 W, 1.
Discharge time in a region such as 5 W is becoming an important characteristic.

To improve the discharge characteristics, it is advantageous to fill more active material, but to improve the leakage resistance, it is advantageous to use a smaller amount of the active material.
That is, it is important to determine the filling amounts of the positive electrode and the negative electrode in consideration of the balance between the two characteristics.

[0004]

By the way, the discharge time in the heavy load region has special characteristics compared to the discharge in the light load and medium load regions. In the heavy load region, discharge only for the amount of the filled electrode active material is not performed. With current battery technology,
It is possible to discharge only at a certain ratio of the inserted mass of the active material. This ratio, or utilization,
It is determined by a voltage loss due to an increase in internal resistance and diffusion of a reaction source compound (H ₂ O, OH ⁻ ). This utilization factor has different values for the positive electrode and the negative electrode. Therefore, in order to more efficiently improve the discharge characteristics in the heavy load region, the filling amounts of the positive electrode and the negative electrode should be determined so that the same amount of the positive electrode and the negative electrode is used.

The present invention has been proposed in view of the above-described conventional circumstances, and has as its object to provide an alkaline battery having more efficiently improved discharge characteristics in a heavy load region.

[0006]

The alkaline battery of the present invention is an alkaline battery having a positive electrode, a negative electrode, and an alkaline electrolyte, wherein the solid content of the positive electrode is W _C and the solid content of the negative electrode is W _A. when the ratio W _a / W _C of the negative electrode solid content with respect to the positive electrode solid content, 0.35 or more, characterized in that it is in the range of 0.41 or less.

In the above-described alkaline battery according to the present invention, since the ratio between the solid content of the positive electrode and the solid content of the negative electrode is specified, the utilization factor of the positive electrode and the utilization factor of the negative electrode are balanced, and The substance is used effectively.

Further, the alkaline battery of the present invention comprises a positive electrode,
An alkaline battery comprising a negative electrode and an alkaline electrolyte, wherein the water content of the whole battery reaction system including the positive electrode, the negative electrode and the alkaline electrolyte is 0.190 or more, 0.250
It is characterized by the following range.

In the above-described alkaline battery according to the present invention, since the water content in the entire battery reaction system is regulated, an ion conduction path between the positive and negative electrodes is well secured, and an increase in internal resistance is prevented. .

[0010]

Embodiments of the present invention will be described below.

FIG. 1 shows a configuration example of a battery according to the present embodiment. The alkaline battery 1 was formed in a hollow cylindrical positive electrode 3 in a hollow cylindrical battery can 2 having a bottom and having an opening so as to be in contact with the positive electrode 3 and formed in a cylindrical shape with a bottom. The separator 4, a negative electrode 5 disposed inside the separator 4, and an electrolytic solution for conducting ions are housed. The alkaline battery 1 includes a sealing unit that seals the opening of the battery can 2.

The cathode 3 is made of chemically synthesized manganese dioxide (CM).
D), a positive electrode mixture composed of natural manganese dioxide (NMD), electrolytic manganese dioxide (EMD), graphite, an aqueous solution of potassium hydroxide, or the like is formed in a hollow cylindrical shape, and is arranged along the inner wall surface of the battery can 2. You.

The negative electrode 5 is made of a gelled negative electrode mixture alloyed with indium, bismuth and the like, containing a zinc alloy powder substantially free of lead and mercury, an aqueous solution of potassium hydroxide, a thickener and the like. . The negative electrode mixture is injected into the bottomed cylindrical separator 4.

The separator 4 is made of, for example, a polyolefin non-woven fabric, and is disposed so as to contact the hollow portion of the positive electrode 3 formed in a cylindrical shape.

The sealing unit is provided with a gasket 6 and a negative electrode terminal 7 at the opening of the battery can 2 and is assembled in this order. The gasket 6 is provided with a through hole at the center thereof, and a needle-like current collecting pin 8 is press-fitted from the through hole.
The current collecting pin 8 is made of, for example, brass or the like, and is pressed into the through hole provided at the center of the gasket 6 from the outside and welded to the negative electrode terminal 7. As shown in FIG. 1, when the gasket 6 seals the opening of the battery can 2 together with the negative electrode terminal 7, the outer peripheral portion of the gasket 6 is formed integrally with the positive electrode terminal 9. Between the battery can 2 and the negative electrode terminal 7. The outer surface of the battery can 2 is covered with an exterior label 10.

Here, as described above, in order to obtain a higher level of characteristics while maintaining the balance between the discharge characteristics and the leakage resistance characteristics of the battery, it is necessary to efficiently and wastefully.
It is important to maximize the active material loading. For this purpose, the input balance between the positive electrode active material and the negative electrode active material becomes very important.

Although the conventional concept of input capacity has been described only for manganese dioxide for the positive electrode and only for the zinc alloy for the negative electrode, as a result of various studies by the present inventors, the water content, KOH
The inventor has conceived that the influence of the amount is large, and has completed the present invention.

That is, in the alkaline battery of the present invention, the water content R _w is defined in the range of 0.190 to 0.250. Furthermore, more preferable range of the moisture content moisture content R _w is 0.200 or more and 0.230 or less.

Here, the water content R _w is obtained as follows.

First, the positive electrode solid content (W _C ) was determined by taking out only the positive electrode from the completed battery and measuring the wet weight (W _CW ).
After washing and drying, the weight is measured. For washing the positive electrode, for example, the positive electrode taken out is put into distilled water, and solid content is taken out by decantation after centrifugation. This is distilled water for a total of 2
2 times with alcohol. The drying method is not particularly limited, and examples thereof include vacuum drying and heat drying.

The negative electrode solid content (W _A ) was determined by taking out only the negative electrode together with the separator from the completed battery, and calculating the wet weight (W _Aw ).
After measurement, the weight is measured after washing and drying. Cleaning of the negative electrode,
Drying is performed in the same manner as in the case of the positive electrode. Further, the separator is also washed and dried, and the dry weight (W _S ) is measured.

Then, the moisture content R _w is obtained from the following equation.

R _w = (W _CW + W _Aw −W _C −W _A −W _S ) / (W _CW + W _Aw ) In the _undischarged state, if the water content is too large, the positive electrode obtained by compression-molding the powder is used. In addition, the shape retention of the negative electrode, which retains its shape by gelling the powder, is hindered, and the internal resistance is increased by increasing the number of dead active materials that are not electrically connected, so to speak.

During discharge, water is consumed by the electrode reaction together with the electrode active material. In the discharge reaction, moisture continues to be supplied to the electrode surface by the electrode surface by migration / diffusion. At this time, if the amount of water around the electrodes is insufficient, the diffusion resistance increases, causing a decrease in discharge voltage.

In the last stage of the discharge, when the amount of water is small, the ratio of filling the voids in the separator and the positive electrode decreases, so that the ion conduction path between the positive electrode and the negative electrode decreases, thereby increasing the internal resistance.

As described above, water plays an important role as an active material and a solvent for the discharge reaction, and the water content R
_By defining _w in the range of 0.190 or more and 0.250 or less, an ion conduction path between the positive electrode and the negative electrode is favorably secured, and an increase in internal resistance is prevented.

Further, since the mixing ratio of the positive and negative electrode mixture of the alkaline battery is almost completely completed, there is little need to stick to the “weight of the active material”. For example, the solid content of the positive electrode mixture is composed of manganese and graphite,
Approximately the ratio is 9: 1. The solid content of the negative electrode mixture is composed of a zinc alloy, a gelling agent, additives, and the like, and the ratio of the zinc alloy powder accounts for 95% or more of the entire solid content. For the above reasons, the balance of the input capacitance is determined by the ratio of the solid content of each electrode.

That is, in the alkaline battery 1 of the present invention,
Assuming that the positive electrode solid content is W _C and the negative electrode solid content is W _A , the ratio of the negative electrode solid content to the positive electrode solid content W _A / W _C
Is in the range of 0.35 or more and 0.41 or less. Even if W _A / W _C is larger or smaller than the above range, the utilization rate of the positive electrode and the utilization rate of the negative electrode cannot be balanced,
The input active material is not used effectively. If the charged active material is not used effectively, good charge / discharge characteristics cannot be obtained.

Therefore, when the ratio W _A / W _C of the positive electrode solid content amount W _A and the negative electrode solid content amount W _C is in the range of 0.35 or more and 0.41 or less, the utilization rate of the positive electrode and the utilization rate of the negative electrode are determined. And the active material that has been input can be used effectively. Therefore, in the alkaline battery, the charge / discharge characteristics, particularly in the heavy load region, can be remarkably improved by effectively using the input active material. Further, the more preferable range of the ratio of the negative electrode solid content to the positive electrode solid content W _A / W _C is 0.37 or more,
0.40 or less.

In the alkaline battery 1 according to the present invention configured as described above, since the ratio between the solid content of the positive electrode and the solid content of the negative electrode is specified, the utilization rate of the positive electrode and the utilization rate of the negative electrode are balanced. Thus, the charged active material can be effectively used to have good discharge characteristics.

Further, in the alkaline battery 1 according to the present invention, since the moisture content is regulated, a good ion conduction path between the positive electrode and the negative electrode is ensured, an increase in internal resistance is prevented, and good discharge characteristics are obtained. Will have.

In the alkaline battery 1 of the present invention, the above-mentioned conditions of the ratio of the solid content of the positive electrode to the solid content of the negative electrode, or
Even if one of the conditions of the moisture content is satisfied,
Although the effects of the present invention can be sufficiently obtained, when both the conditions of the solid content ratio and the moisture content are satisfied, the alkaline battery 1
The used active material is effectively used, and an increase in internal resistance is prevented, so that particularly good discharge characteristics are obtained.

In the above-described embodiment, the cylindrical alkaline battery 1 has been described as an example. However, the present invention is not limited to this, and the present invention is applicable to batteries having different sizes and shapes. Applicable.

The present invention also relates to the alkaline battery 1 described above.
As described above, the present invention is particularly effective when applied to an alkaline battery having a structure in which the negative electrode 5 is disposed via the separator 4 in the hollow portion of the hollow cylindrical positive electrode 3. However, the present invention is not limited to this, and can be applied to an alkaline battery in which the positive electrode and the negative electrode are arranged differently.

[0035]

EXAMPLES The present invention will now be described by way of examples which were carried out to confirm the effects of the present invention. However, it goes without saying that the present invention is not limited to these examples.

In the following examples, LR6 type was used.
Although a so-called AA cylindrical alkaline battery is manufactured, the present invention can be applied to batteries having different sizes and shapes. Further, in the following examples, specific numerical values are given for the solid content weight and the wet weight of the positive electrode and the negative electrode, but these numerical values are not absolute. This is because these values vary depending on the specifications of the battery, such as the sealing structure of the battery can. Further, the specifications of the separator and the alloy composition of the zinc powder are not limited to the following examples.

<Sample 1> First, manganese and graphite were mixed at a ratio of about 9: 1, and a slight amount of a KOH electrolytic solution was added to the mixture to prepare a positive electrode mixture. This positive electrode mixture was molded in a battery can into a hollow cylindrical shape having an outer diameter of 13.3 mm, an inner diameter of 9.0 mm, and a height of 42 mm. The hollow portion of the positive electrode was filled with a hollow bottomed cylindrical separator.

Next, zinc powder, a gelling agent and a KOH electrolyte were mixed at a ratio of about 65: 1: 34, and a small amount of an additive was added to the mixture to prepare a negative electrode mixture. This negative electrode mixture was filled in the separator, and the sealed structure and the battery can were fitted to each other to produce an LR6 type alkaline dry battery.

<Samples 2 to 14> The wet weight of the positive electrode, the solid weight of the positive electrode, the dry weight of the separator, the wet weight of the negative electrode, the solid weight of the negative electrode, the solid content ratio, and the moisture content were changed as shown in Table 1 below. Except for this, an LR6-type alkaline dry battery was produced in the same manner as in Sample 1.

Here, the solid content ratio and the water content are obtained as follows.

First, the positive electrode solid content (W _C ) was determined by taking out only the positive electrode from the completed battery and measuring the wet weight (W _CW ).
After washing and drying, the weight was measured. Washing of the positive electrode was carried out by placing the positive electrode taken out in distilled water, centrifuging it, and taking out the solid matter by decantation. This was performed twice with distilled water and twice with alcohol. Drying was performed by vacuum drying. The drying time was one hour, and the degree of vacuum after one hour was 0.03 mmHg.

The solid content of the negative electrode (W _A ) was determined by taking out only the negative electrode together with the separator from the completed battery, and calculating the wet weight (W _Aw ).
After the measurement, the weight was measured after washing and drying. Cleaning of the negative electrode,
Drying was performed in the same manner as in the case of the positive electrode. Further, the separator was also washed and dried, and the dry weight (W _S ) was measured.

Then, the water content R _w was obtained from the following equation.

[0044] R _w = The _{(W CW + W Aw -W C} -W A -W S) / (W CW + W Aw), solid content from the ratio W _A / W _C of the negative electrode solid content with respect to the positive electrode solids content I asked.

The battery characteristics of the battery fabricated as described above were evaluated.

The heavy load discharge characteristics are as follows:
The test was performed after storing for 1 week in an environment at a temperature of 60 ° C. and a humidity of 60% RH. First, continuous discharge was performed at a constant current of 1 A to a final voltage of 0.9 V, and the discharge time was measured. In addition, this test was performed for each of 9 sample batteries, and the average thereof was obtained.

The leakage characteristics of each of the 20 sample batteries were visually observed after storage for 60 days in an environment of 60 ° C. and 90 RH (temperature ± 5 ° C., humidity ± 10% RH). Then, the number of batteries for which leakage was confirmed was counted. In addition, the leak mode of the battery was all performed by opening the safety valve.

With respect to the alkaline batteries of Samples 1 to 14, the evaluation results of the heavy load discharge characteristics and the liquid leakage characteristics were obtained by measuring the positive electrode wet weight, the positive electrode solid content, the separator dry weight, the negative electrode wet weight, the negative electrode solid weight, and the solid content. The results are shown in Table 1 together with the ratio and the water content.

[0049]

[Table 1]

First, looking at the solid content ratio in the table, it is clear from Table 1 that the alkaline battery having the solid content ratio in the range of 0.35 or more and 0.41 or less has a positive electrode utilization rate. And the utilization factor of the negative electrode are balanced, and it can be seen that long-time discharge can be performed even in a heavy load discharge state. It can be seen that particularly good results were obtained when the solid content ratio was 0.37 or more and 0.40 or less.

On the other hand, in an alkaline battery having a solid content ratio of less than 0.35 or an alkaline battery having a solid content ratio of more than 0.41,
Since the utilization rate of the positive electrode and the utilization rate of the negative electrode cannot be balanced and the active material that has been used is not used effectively, the discharge time is short.

Therefore, when the ratio between the solid content of the positive electrode and the solid content of the negative electrode is in the range of 0.35 or more and 0.41 or less, the utilization of the positive electrode and the utilization of the negative electrode can be balanced.
It has been found that good discharge characteristics can be obtained by effectively using the charged active material.

Next, regarding the moisture content, when the moisture content is in the range of 0.190 or more and 0.250 or less,
It can be seen that since an ion conduction path between the positive electrode and the negative electrode is well secured and an increase in internal resistance is prevented, a long-time discharge can be performed even in a heavy load discharge state. Among them, particularly, the water content is 0.200 or more, 0.2
It can be seen that particularly good results are obtained when the range is 30 or less.

On the other hand, when the water content is smaller than 0.190, the diffusion resistance of water at the time of discharge increases, and the ion conduction path decreases, so that the discharge voltage decreases. When the moisture content is larger than 0.250,
Since the shape retention of the negative electrode is hindered and electrical connection is hindered, the internal resistance increases. Also, it can be seen that a large amount of water causes battery leakage.

Therefore, the moisture content should be 0.190 or more, 0.2
It was found that by setting the ratio to 50 or less, a favorable ion conduction path between the positive electrode and the negative electrode was obtained, an increase in internal resistance was prevented, and good discharge characteristics were obtained.

When both the conditions of the solid content ratio and the moisture content are satisfied, that is, the ratio of the positive electrode solid content to the negative electrode solid content is in the range of 0.35 or more and 0.41 or less, and When the rate is in the range of 0.190 or more and 0.250 or less, the charged active material is used effectively, and the internal resistance is prevented from increasing. You can see that it is.

[0057]

In the alkaline battery according to the present invention, since the ratio between the solid content of the positive electrode and the solid content of the negative electrode is specified, the utilization of the positive electrode and the utilization of the negative electrode can be balanced.
Good discharge characteristics are realized by effectively using the charged active material.

Further, in the alkaline battery according to the present invention, since the moisture content is specified, a good ion conduction path between the positive electrode and the negative electrode is ensured, and an increase in internal resistance is prevented, thereby realizing good discharge characteristics. Is done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one configuration example of an alkaline battery of the present invention.

[Explanation of symbols]

1 Alkaline battery, 2 Battery can, 3 Positive electrode, 4
Separator, 5 negative electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kenta Yamamoto, Inventor 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Naoki Hayashi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5H024 AA03 CC02 CC14 DD14 HH01

Claims (3)

[Claims] And 1. A positive electrode, a negative electrode, the alkaline battery and an alkaline electrolyte, the positive electrode solids content and W _C, when the negative electrode solid content was W _A, the ratio W of the negative electrode solid content with respect to the positive electrode solids content _A / W _C
Is in the range of 0.35 or more and 0.41 or less. 2. The alkaline battery according to claim 1, wherein a water content R _{w of the} whole battery reaction system including the positive electrode, the negative electrode, and the alkaline electrolyte is in a range of 0.190 to 0.250. . 3. A positive electrode, a negative electrode, the alkaline battery including an alkaline electrolyte, the positive electrode, moisture content R _w for the entire cell reaction system including a negative electrode and an alkaline electrolyte, 0.190 or more, 0.250
An alkaline battery having the following range.