JP2015138668A - alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline battery superior in heavy load discharge performance.SOLUTION: An alkaline battery 1 comprises: a positive electrode mixture 21 including a manganese dioxide and a conductive material; a separator 22 provided on an inner peripheral side of the positive electrode mixture 21; a negative electrode mixture 23 filled on the inner peripheral side of the separator 22, and including powder having zinc as a primary component; and a negative electrode current collector 31 put in the negative electrode mixture 23, which are inserted in a bottomed cylindrical positive electrode can 11. The alkaline battery further comprises: a negative electrode terminal plate 32 sealing an opening of the positive electrode can 11; and an alkaline electrolytic solution. The powder includes particles of 75 μm or smaller in particle size in a range of 25-40 mass%. The positive electrode mixture 21 includes hollow cylindrical pellets 21a, 21b, 21c coaxially stacked and inserted in the positive electrode can 11. The total length "s" of gaps 51, 52 between the pellets in an axial direction of the positive electrode can 11 is 1-14% of the total length "d" of the pellets in the axial direction.

Description

  The present invention relates to an improvement in discharge performance of an alkaline battery, particularly heavy load discharge performance.

  In recent years, electronic devices such as digital cameras, video cameras, mobile phones, and smartphones have been improved in performance and miniaturization. The performance of alkaline batteries used as power sources for such electronic devices has been improved, especially heavy load discharge performance (high load). There is an increasing demand for improvement in discharge characteristics.

  As a technique for improving the high-load discharge characteristics of an alkaline battery, for example, Patent Document 1 includes a negative electrode including a zinc alloy powder containing 20 to 50% by weight of a fine powder having a particle size of 75 μm or less, a positive electrode, a negative electrode, and a positive electrode. In the constant resistance discharge, the alkaline battery is configured so that the time when the potential of the negative electrode rises is shorter than the time when the potential of the positive electrode falls. ing.

Japanese Patent No. 5172181

  In the above-mentioned Patent Document 1, the heavy load discharge characteristics are improved by using a zinc alloy powder containing 20 to 50% by weight of a fine powder having a particle size of 75 μm or less as the negative electrode material. Even when a fine powder is used, the heavy load discharge characteristics may not be improved. This is thought to be because the fine powder with a small particle size has a large specific surface area, so that the electrolyte is easily held on the negative electrode side, thereby reducing the electrolyte on the positive electrode side and increasing the electrical resistance on the positive electrode side. It is done.

  The object of the present invention is to provide an alkaline battery with improved discharge performance of the alkaline battery, in particular, excellent heavy load discharge performance.

  One aspect of the present invention for achieving the above object is that a positive electrode mixture loaded in a bottomed cylindrical positive electrode can, a separator provided on an inner peripheral side of the positive electrode mixture, and the separator A negative electrode mixture containing powder containing zinc as a main component, filled in the inner peripheral side, a negative electrode current collector inserted into the negative electrode mixture, a negative electrode terminal plate for sealing the opening of the positive electrode can, An alkaline battery comprising an alkaline electrolyte, wherein the positive electrode mixture includes manganese dioxide and a conductive material, and the powder has a particle size of 25 to 40% by mass in a range of 75 μm or less. The positive electrode mixture is composed of a plurality of hollow cylindrical pellets that are stacked and loaded coaxially with the positive electrode can in the positive electrode can, a gap is provided between the pellets, and the gap The total length s along the axial direction of the positive electrode can is the pellet It is characterized in that 1 to 14% based on the total d of the length along the bets of each said axial.

Another aspect of the present invention is the alkaline battery, wherein the density of the pellets is in a range of 3.0 to 3.7 g / cm ³ .

  Another aspect of the present invention is the alkaline battery, wherein the pellet includes graphite as the conductive material in a range of 5 to 20% by mass with respect to the manganese dioxide.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  ADVANTAGE OF THE INVENTION According to this invention, the alkaline battery excellent in discharge performance, especially heavy load discharge performance can be provided.

It is a figure which shows the structure of a general cylindrical alkaline battery.

  FIG. 1 shows a configuration of a general cylindrical alkaline battery (LR6 type (AA) alkaline battery) (hereinafter referred to as alkaline battery 1) to which the present invention is applied. In the figure, the alkaline battery 1 is shown as a vertical cross-sectional view (a cross-sectional view when the extending direction of the cylindrical axis of the alkaline battery 1 is the vertical (vertical) direction).

  As shown in FIG. 1, the alkaline battery 1 includes a bottomed cylindrical metal battery can (hereinafter referred to as a positive electrode can 11), a positive electrode mixture 21 inserted into the positive electrode can 11, and a positive electrode mixture 21. A bottomed cylindrical separator 22 provided on the inner peripheral side, a negative electrode mixture 23 filled on the inner peripheral side of the separator 22, and a negative electrode fitted into the opening of the positive electrode can 11 via a resin sealing gasket 35 A terminal plate 32 and a rod-shaped negative electrode current collector 31 made of a material such as brass, which is fixed inside the negative electrode terminal plate 32 by spot welding or the like, are provided. The positive electrode mixture 21, the separator 22, and the negative electrode mixture 23 constitute the power generation element 20 of the alkaline battery 1.

  The positive electrode can 11 is conductive and is formed, for example, by pressing a metal material such as a nickel-plated steel plate. The positive electrode can 11 also functions as a positive electrode current collector and a positive electrode terminal, and a convex positive electrode terminal portion 12 is integrally formed at the bottom thereof.

  The positive electrode mixture 21 is a mixture of electrolytic manganese dioxide (EMD) as a positive electrode active material, graphite as a conductive material, and an electrolytic solution mainly composed of potassium hydroxide (KOH) together with a binder such as polyacrylic acid, The mixture is processed in steps such as rolling, crushing, granulating, and classifying, and then compressed and formed into an annular shape. As shown in the drawing, in the positive electrode can 11, a plurality of hollow cylindrical three pellets 21 a, 21 b, 21 c constituting the positive electrode mixture 21 are coaxial with the cylindrical axis of the positive electrode can 11. In such a manner, they are stacked in the vertical direction and press-fitted. The length along the axial direction of each positive electrode can 11 of each pellet 21a, 21b, 21c is d1, d2, d3 in order. In the present embodiment, the lengths of the pellets 21a, 21b, and 21c are matched (d1 = d2 = d2), but they may not be matched.

  As shown in the figure, gaps 51 and 52 are provided between the pellet 21a and the pellet 21b and between the pellet 21b and the pellet 21c. The length along the axial direction of the positive electrode can 11 of the gap 51 between the pellet 21a and the pellet 21b is s1, and the length along the axial direction of the positive electrode can 11 of the gap 52 between the pellet 21b and the pellet 21c. The length is s2. The surface of the pellet 21 c on the positive electrode terminal portion 12 side is in close contact with the positive electrode can 11.

  The negative electrode mixture 23 is a gelled zinc alloy powder as a negative electrode active material. Zinc alloy powder is powdered by gas atomization method or centrifugal spray method, zinc, alloy components added for the purpose of suppressing gas generation (leakage prevention), etc. (bismuth, aluminum, indium, etc.), And potassium hydroxide as an electrolyte. The negative electrode current collector 31 is inserted into the central portion of the negative electrode mixture 23.

  About the alkaline battery 1 which consists of the above structure, in order to verify the improvement effect of discharge performance, especially heavy load discharge performance, the following tests 1-3 were performed.

<Test 1>
In Test 1, the particle size of the zinc alloy powder of the negative electrode mixture 23 and the particle size of the zinc alloy powder of the negative electrode mixture 23 are verified in order to verify an appropriate range as the gaps 51 and 52 between the pellets constituting the positive electrode mixture 21. (Change the content ratio of particles having a particle size of 75 μm or less (hereinafter also referred to as “the ratio of particles of 75 μm or less”) in the range of 20.0 to 45.0 mass%) and the size of the gaps 51 and 52 (The ratio of the total length s = s1 + s2 of the gaps 51 and 52 along the axial direction of the positive electrode can 11 to the total length of the pellets along the axial direction of the positive electrode can 11 d = d1 + d2 + d3) (Hereinafter also referred to as “gap / mixture height”)), a plurality of alkaline batteries 1 were produced, and the discharge performances were compared. In any alkaline battery 1, the positive electrode mixture 21 has a density (hereinafter also referred to as “positive electrode mixture density”) of 3.2 g / cm ³ , and manganese dioxide contained in the positive electrode mixture 21 A graphite having a ratio (hereinafter also referred to as “graphite / manganese dioxide”) of 10.0% by mass was used.

  Comparison of discharge performance is based on a cycle discharge test assuming heavy load discharge when using a digital camera (2 discharges at 1500 mW, 28 discharges at 650 mW 10 times per hour (the rest period per hour is About 55 minutes)), and the number of cycles up to the end voltage (1.05 V) was counted and compared.

  Table 1 shows the result of comparing the discharge performance of each alkaline battery 1. In addition, the numerical value in the table | surface showing discharge performance is a relative value when the discharge performance of the alkaline battery 1 of the comparative example 3 in a table | surface is set to 100. FIG.

表１に示すように、負極合剤２３の亜鉛合金粉末として粒度が７５μｍ以下の粒子を２５〜４０質量％の範囲で含み、かつ、隙間５１，５２の合計ｓとペレットの軸方向長さの合計ｄとの比（隙間／合剤高さ）を１〜１４％としたアルカリ電池１について、放電性能が高くなることが確認された（実施例１〜７）。また、負極合剤２３の亜鉛合金粉末として粒度が７５μｍ以下の粒子を３０質量％の範囲で含むものを用い、かつ、隙間５１，５２の合計ｓとペレットの軸方向長さの合計ｄとの比（隙間／合剤高さ）を８．０％とした場合に、放電性能がとくに高くなることが確認された（実施例５）。 Table 1

As shown in Table 1, the zinc alloy powder of the negative electrode mixture 23 contains particles having a particle size of 75 μm or less in a range of 25 to 40% by mass, and the total s of the gaps 51 and 52 and the axial length of the pellet It was confirmed that the discharge performance of the alkaline battery 1 in which the ratio (gap / mixture height) to the total d was 1 to 14% was high (Examples 1 to 7). Further, as the zinc alloy powder of the negative electrode mixture 23, a powder containing particles having a particle size of 75 μm or less in a range of 30% by mass, and the total s of the gaps 51 and 52 and the total d of the axial lengths of the pellets It was confirmed that the discharge performance was particularly improved when the ratio (gap / mixture height) was 8.0% (Example 5).

  Moreover, from Comparative Example 2, it was found that the discharge performance was not improved when the amount of the fine powder of the negative electrode mixture 23 was too large. This is presumably because the fine powder having a small specific particle size with a large specific surface area makes it easier to hold the electrolytic solution on the negative electrode side, thereby reducing the electrolytic solution on the positive electrode side and increasing the electrical resistance on the positive electrode side.

  Moreover, from Comparative Examples 3 and 4, it was found that if the gaps 51 and 52 are too small, the discharge performance is not improved. This is considered to be because when the gaps 51 and 52 are too small, a sufficient amount of the electrolyte is not retained on the positive electrode side.

  Further, it was found from Comparative Example 5 that the discharge performance is not improved if the gaps 51 and 52 are too large. This is considered to be because if the gaps 51 and 52 are too large, the amount of the negative electrode active material facing the positive electrode active material is reduced and the current density is increased.

<Test 2>
Subsequently, in order to verify an appropriate range as the density of the positive electrode mixture 21 (positive electrode mixture density), the density of the positive electrode mixture 21 was changed (the density of the positive electrode mixture 21 was 2.8 to 3.7 g / cm). ^A plurality of alkaline batteries 1 (changed in the range of ³ ) were prepared, and their discharge performances were compared. In any of the alkaline batteries 1, the ratio (gap / mixture height) of the total s of the gaps 51 and 52 to the total d of the axial lengths of the pellets was 5.0%. In any alkaline battery 1, a positive electrode mixture 21 having a ratio of manganese dioxide to graphite contained therein (graphite / manganese dioxide) of 10.0% by mass was used. The discharge performance was determined by the same method as in Test 1.

  Table 2 shows the results of comparing the discharge performance of each alkaline battery 1. In addition, the numerical value in the table | surface showing discharge performance is a relative value when the discharge performance of the alkaline battery 1 of the comparative example 3 shown in Table 1 is set to 100. FIG.

表２に示すように、正極合剤２１の密度（正極合剤密度）が３．０〜３．７ｇ／ｃｍ^３の範囲においてアルカリ電池１の放電性能が高くなることが確認された（実施例８，９）。また正極合剤２１の密度が３．０ｇ／ｃｍ^３の場合に、とくに放電性能が高くなることが確認された（実施例８）。 Table 2

As shown in Table 2, it was confirmed that the discharge performance of the alkaline battery 1 is high when the density of the positive electrode mixture 21 (positive electrode mixture density) is in the range of 3.0 to 3.7 g / cm ³ (Examples). 8, 9). It was also confirmed that the discharge performance was particularly improved when the density of the positive electrode mixture 21 was 3.0 g / cm ³ (Example 8).

  On the other hand, if the density of the positive electrode mixture 21 was too high, cracking was likely to occur and compression molding became difficult, and pellets could not be produced (Comparative Example 6).

  Moreover, when the density of the positive electrode mixture 21 was too low, sufficient discharge performance could not be obtained (Comparative Example 7). This is probably because if the density of the positive electrode mixture 21 is too low, the conductivity inside the positive electrode mixture 21 becomes insufficient.

<Test 3>
Subsequently, the ratio was changed in order to verify an appropriate range as the ratio of manganese dioxide to graphite (graphite / manganese dioxide) contained in the positive electrode mixture 21 (the ratio was 2.0 to 25.0 mass%). A plurality of alkaline batteries 1 were prepared and their discharge performances were compared. The discharge performance was determined by the same method as described above. In any of the alkaline batteries 1, the ratio (gap / mixture height) of the total s of the gaps 51 and 52 to the total d of the axial lengths of the pellets was 5.0%. Moreover, about any alkaline battery 1, the thing whose density (positive electrode mixture density) of the positive electrode mixture 21 is 3.2 g / cm < ³ > was used.

  Table 3 shows the results of comparing the discharge performance of the alkaline batteries 1. In addition, the numerical value in the table | surface showing discharge performance is a relative value when the discharge performance of the alkaline battery 1 of the comparative example 3 shown in Table 1 is set to 100. FIG.

表３に示すように、正極合剤２１に含まれる二酸化マンガンと黒鉛との比（黒鉛／二酸化マンガン）が５〜２０質量％の範囲において放電性能が高くなることが確認された（実施例１０〜１２）。また正極合剤２１に含まれる二酸化マンガンと黒鉛との比（黒鉛／二酸化マンガン）が１５．０質量％の場合に、とくに放電性能が高くなることが確認された（実施例１１）。 Table 3

As shown in Table 3, it was confirmed that the discharge performance was enhanced when the ratio of manganese dioxide to graphite (graphite / manganese dioxide) contained in the positive electrode mixture 21 was 5 to 20% by mass (Example 10). ~ 12). Further, it was confirmed that discharge performance was particularly improved when the ratio of manganese dioxide to graphite (graphite / manganese dioxide) contained in the positive electrode mixture 21 was 15.0 mass% (Example 11).

  Moreover, when the ratio of graphite was too small, sufficient discharge performance could not be obtained (Comparative Example 8). This is considered to be due to insufficient conductivity inside the positive electrode mixture 21.

  Moreover, even if there was too much ratio of graphite, sufficient discharge performance was not obtained (comparative example 9). This is presumably because the amount of the electrolytic solution in the positive electrode mixture 21 decreased due to the influence of water-repellent graphite.

<Effect>
As described above, the zinc alloy powder of the negative electrode mixture 23 contains particles having a particle size of 75 μm or less in a range of 25 to 40% by mass, and the total s of the gaps 51 and 52 and the total d of the axial lengths of the pellets The discharge performance of the alkaline battery 1 is increased when the ratio is 1 to 14%, and in particular, the zinc alloy powder of the negative electrode mixture 23 containing particles having a particle size of 75 μm or less in the range of 30% by mass, and It was found that good results were obtained when the ratio of the total s of the gaps 51 and 52 to the total length d of the pellets in the axial direction was 8.0%.

Further, it was confirmed that the density of the positive electrode mixture 21 becomes higher discharge performance in a range of 3.0~3.7g / cm ^3, particularly good when the density of the positive electrode mixture 21 is 3.0 g / cm ³ It was found that a good result was obtained.

  Further, it was confirmed that the discharge performance was enhanced when the ratio of manganese dioxide to graphite (graphite / manganese dioxide) contained in the positive electrode mixture 21 was in the range of 5 to 20% by mass, and in particular, the dioxide dioxide contained in the positive electrode mixture 21. It was found that good results were obtained when the ratio of manganese to graphite (graphite / manganese dioxide) was 15.0% by mass.

  In addition, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, although the number of pellets constituting the positive electrode mixture 21 is three in the above embodiment, the number of pellets may be two or four or more. In short, together with other necessary conditions, the ratio of the total length s along the axial direction of the positive electrode can 11 of the gap between the pellets to the total length d along the axial direction of the pellets should satisfy the above condition. By doing so, the above effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Alkaline battery, 11 Positive electrode can, 12 Positive electrode terminal part, 20 Electric power generation element, 21 Positive electrode mixture, 21a, 21b, 21c Pellet, 22 Separator, 23 Negative electrode mixture, 31 Negative electrode current collector, 32 Negative electrode terminal plate, 35 Sealing gasket , 51,52 Clearance

Claims (3)

A positive electrode mixture loaded in a bottomed cylindrical positive electrode can; a separator provided on an inner peripheral side of the positive electrode mixture; and a powder containing zinc as a main component, which is filled on the inner peripheral side of the separator. A negative electrode material mixture, a negative electrode current collector inserted into the negative electrode material mixture, a negative electrode terminal plate that seals an opening of the positive electrode can, and an alkaline electrolyte. And
The positive electrode mixture includes manganese dioxide and a conductive material,
The powder includes particles having a particle size of 75 μm or less in a range of 25 to 40% by mass,
The positive electrode mixture consists of a plurality of hollow cylindrical pellets that are stacked and loaded coaxially with the positive electrode can in the positive electrode can,
A gap is provided between the pellets, and the total length s of the gap along the axial direction of the positive electrode can is 1 to 1 with respect to the total length d of the pellets along the axial direction. An alkaline battery characterized by being 14%. The alkaline battery according to claim 1, wherein the density of the pellet is in a range of 3.0 to 3.7 g / cm ³ .   3. The alkaline battery according to claim 1, wherein the pellet includes graphite as the conductive material in a range of 5 to 20 mass% with respect to the manganese dioxide.

Images