JP2009080998A - Separator material for alkaline cell, and alkaline cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline cell in which an internal short circuit due to a crystal formation of zinc-oxide is hard to occur and a discharge performance is excellent. <P>SOLUTION: The separator 14 for an alkaline cell 10 is made of a separator material having a basis weight of A(g/m<SP>2</SP>), a thickness B(mm) and an air-permeability C(sec/100mL), and the average number of the separators when arranged between a positive electrode active material and a negative electrode active material is D (number of plates). In this case, a value of A×B×logC×D<SP>2</SP>is 14 or more and 22 or less. For example, if the basis weight A is 40g/m<SP>2</SP>or less, the thickness B is 0.120 mm or less and the air permeability C is 5.4 sec/100mL or more and 14 sec/100mL or less, the average number of the separators D is 2 or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an alkaline battery separator material and an alkaline battery configured using the same.

In a conventional general alkaline battery, a separator impregnated with an alkaline electrolyte is interposed between a positive electrode using a positive electrode active material such as manganese dioxide or nickel oxyhydroxide and a negative electrode using gelled zinc or the like. (For example, refer patent document 1). For this type of alkaline battery, improvement in discharge performance is required due to the recent spread of digital devices. And as one means for achieving such an improvement in discharge performance, a thin film separator has been proposed. That is, the reduction in the thickness of the separator contributes not only to increasing the filling amount of the positive electrode active material and the negative electrode active material, but also to increasing the efficiency of the discharge reaction by shortening the distance between the positive electrode and the negative electrode.
JP 2007-141672 A

  However, in an alkaline battery containing a zinc alloy powder in the negative electrode active material, zinc oxide crystals may be generated in the negative electrode when used under specific discharge conditions, and this crystal breaks through the thinned separator. There is a disadvantage that it penetrates and causes an internal short circuit. Therefore, when such an internal short circuit occurs, the shielding performance, which is the original function of the separator, decreases, resulting in a decrease in discharge performance.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize an alkaline battery that is less likely to cause an internal short circuit due to zinc oxide crystal formation and has excellent discharge performance, and such an alkaline battery. An object of the present invention is to provide a separator for an alkaline battery that is suitable.

  Then, in view of the above problems, the inventors of the present application conducted extensive research and focused on a plurality of parameters (specifically, basis weight, thickness, air permeability, average number) regarding the shielding properties of the separator. I came up with the idea of optimizing the interaction of multiple parameters. That is, in the past, a plurality of parameters related to the shielding properties of the separator have been individually examined, but these parameters have not necessarily been studied in a combined manner. And after such examination, the inventors of the present application have newly found a condition that can prevent an internal short circuit without reducing the discharge performance, and finally came up with the invention of the following means [1] to [7]. .

[1] A separator material having a basis weight of A (g / m ² ), a thickness of B (mm), and an air permeability of C (seconds / 100 mL), and is disposed between the positive electrode active material and the negative electrode active material. An alkaline battery composed of separators having an average number of separator materials of D (sheets) when the value of A × B × log C × D ² is 14 or more and 22 or less. battery.

  [2] The alkaline battery according to the above means 1, wherein the separator material is a nonwoven fabric obtained by mixing fibers.

[3] Basis weight A is 40 g / m ² or less, thickness B is 0.120 mm or less, air permeability C is 5.4 seconds / 100 mL or more and 14 seconds / 100 mL or less, and average number D is 2 or less. 3. The alkaline battery according to the above means 1 or 2, characterized in that

[4] Basis weight A is 36 g / m ² or less, thickness B is 0.108 mm or less, air permeability C is 8.0 seconds / 100 mL or more and 26 seconds / 100 mL or less, and average number D is 2 or less. 3. The alkaline battery according to the above means 1 or 2, characterized in that

  [5] Any one of the above means 1 to 4, wherein manganese dioxide or nickel oxyhydroxide is used as the positive electrode active material, zinc alloy powder is used as the negative electrode active material, and an alkaline aqueous solution is used as the electrolyte. The alkaline battery described in 1.

[6] A separator material having a basis weight of A (g / m ² ), a thickness of B (mm), and an air permeability of C (seconds / 100 mL), and a value of A × B × log C is 3. A separator material for an alkaline battery, wherein the separator material is 5 or more and 5.5 or less.

  [7] An alkaline battery configured using the separator material according to means 6.

  As described in detail above, according to the first to fifth and seventh aspects of the invention, it is possible to provide an alkaline battery that is less likely to cause an internal short circuit due to the formation of zinc oxide crystals and has excellent discharge performance.

  Further, according to the invention described in claim 6, it is possible to provide an alkaline battery separator material suitable for realizing the above-described excellent alkaline battery.

  Hereinafter, an alkaline battery 10 according to an embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a positive electrode can 11 constituting a cylindrical alkaline battery 10 of this embodiment is a bottomed cylindrical battery metal part that also serves as a positive electrode current collector. It is formed by drawing press processing. In the internal space of the positive electrode can 11, a power generation element (that is, the positive electrode mixture 13, the separator 14, and the gelled negative electrode mixture 15) can be loaded. Inside the positive electrode can 11, a plurality of positive electrode mixtures 13 formed in a hollow cylindrical shape are vertically stacked and press-fitted concentrically. The positive electrode mixture 13 forming a part of the power generation element is an annular (or tubular) molding mixture containing an oxidizing agent such as manganese dioxide or nickel oxyhydroxide. A bottomed cylindrical separator 14 is inserted inside the positive electrode mixture 13. The separator 14 and the positive electrode mixture 13 are infiltrated with an alkaline electrolyte. The hollow portion of the separator 14 is filled with a gelled negative electrode mixture 15 formed by mixing a zinc alloy powder, a gelling agent, an alkaline electrolyte, and the like. In the present embodiment, an aqueous potassium hydroxide solution is used as the alkaline electrolyte. In the present embodiment, zinc alloy powder containing several tens to several hundred ppm of indium, bismuth and aluminum is used. As the gelling agent, for example, carboxymethyl cellulose, polyacrylic acid and its salts, sodium alginate, etherified starch and the like are suitable.
On the inner surface side of the opening of the positive electrode can 11, a sealing body formed by assembling a plurality of components is attached and crimped, and as a result, the positive electrode can 11 is sealed in a liquid-tight manner. The sealing body includes a negative electrode terminal 21, a sealing gasket 24 as an insulating sealing material, and a negative electrode current collector 26.

  The sealing gasket 24 is an injection-molded part made of a synthetic resin material such as polyolefin such as polypropylene resin. An amide resin such as a polyamide resin may be used instead of the polypropylene resin. The sealing gasket 24 includes a boss portion 25 at the center, and a negative electrode current collector 26 can be inserted into a boss hole that penetrates the boss portion 25.

  The negative electrode current collector 26 is a rod having a circular cross section made of a conductive metal, and its tip is inserted and disposed in the gelled negative electrode mixture 15. On the other hand, the base end portion of the negative electrode current collector 26 is inserted into the boss hole of the boss portion 25 and is fixed to the central portion on the inner surface side of the negative electrode terminal 21 by spot welding or the like.

  The separator 14 used in the alkaline battery 10 of this embodiment is configured to have a bottomed cylindrical shape using a nonwoven fabric obtained by mixing a plurality of types of fibers such as vinylon fibers and rayon fibers. Here, paying attention to a plurality of parameters (basis weight, thickness, air permeability, and average number of sheets) regarding the shielding property of the separator 14, an appropriate value is set in consideration of the interaction.

More specifically, when the basis weight is A (g / m ² ), the thickness is B (mm), and the air permeability is C (seconds / 100 mL), the value of “A × B × log C”. The value of each parameter is set so that becomes 3.5 or more and 5.5 or less. Alternatively, when the basis weight is A (g / m ² ), the thickness is B (mm), the air permeability is C (seconds / 100 mL), and the average number is D (sheets), “A × B × logC The value of each parameter is set so that the value of “× D ² ” is 14 or more and 22 or less. For convenience of explanation, the value of A × B × logC is referred to as “first shielding index”, and the value of A × B × logC × D ² is referred to as “second shielding index”.

Basis weight (A) is a parameter which shows the mass per area of the separator material which comprises the separator 14, Comprising: A fiber will exist densely, so that this value is large, and shielding property becomes high. The basis weight values are be appropriately set on condition that the shielding index falls within the preferred range, preferably 40 g / m ² or less, more preferably 36 g / m ^2. The reason for this is that when the basis weight exceeds 40 g / m ² , the shielding property is increased, while the manufacturing cost of the separator 14 may be increased. In addition, the lower limit value of the basis weight should not be particularly limited, but is set to, for example, 32 g / m ² or more in order to impart the minimum required mechanical strength to the separator material constituting the separator 14. Is good.

  The thickness (B) is a parameter indicating a separation distance between the inner surface and the outer surface of the separator material constituting the separator 14, and generally the larger this value, the higher the shielding property. The thickness value can be appropriately set on condition that the shielding index falls within a suitable range, but is preferably 0.120 mm or less, and more preferably 0.108 mm or less. The reason is that if the thickness exceeds 0.120 mm, the shielding performance is increased, while the manufacturing cost of the separator 14 may be increased. Further, the lower limit value of the thickness should not be particularly limited, but may be set to, for example, 0.080 mm or more in order to impart the minimum required mechanical strength to the separator material constituting the separator 14. Good.

  The air permeability (C) is a parameter indicating the ease with which the fluid passes through the separator material constituting the separator 14, and may be regarded as a parameter indicating the degree of density. The larger the value, the lower the shielding property. The value of the air permeability can be appropriately set on condition that the shielding index falls within a preferable range, but is preferably 5.4 seconds / 100 mL to 14 seconds / 100 mL, preferably 8.0 seconds / 100 mL to 26 seconds. / 100 mL or less is more preferable. The reason is that if the air permeability is too small, it becomes difficult for the alkaline electrolyte to move smoothly through the battery, and the efficiency of the discharge reaction cannot be increased. Moreover, if the air permeability is excessively increased, not only the mechanical strength is likely to be lowered, but also the shielding property that is the original function of the separator 14 is likely to be impaired. In the first and second shielding indexes, the air permeability (C) is a logarithmic value, because the increase / decrease is large compared to other parameters and affects the numerical value, so that it can be reduced. .

  The average number (D) is the average value of the number of sheets (or the number of turns) when the separator material constituting the separator 14 is arranged between the positive electrode active material and the negative electrode active material. Increases, resulting in an increase in shielding. The value of the average number of sheets can be appropriately set on condition that the shielding index falls within a preferable range, but is preferably 2 sheets or less (2 volumes or less). The reason is that when the average number exceeds two, it is necessary to reduce the thickness of one separator material, and it may be difficult to ensure mechanical strength.

Next, several test samples of the alkaline battery 10 are produced, and an evaluation test performed on them is described in detail.
[1. Test sample preparation method]

Here, an AA type (LR6 type) alkaline battery 10 having a structure as shown in FIG. 1 was manufactured under the following conditions. In that case, the values of the basis weight A, the thickness B, and the air permeability C were changed by changing the fiber raw material and manufacturing conditions of the nonwoven fabric constituting the separator material (see Table 1 below). The basis weight A was measured in accordance with JIS P8124. The thickness B was measured in accordance with JIS P8118 using a conventionally known micrometer. The air permeability C was measured according to JIS P8117. Specifically, the time required for 100 mL of air to pass through a subject (separator material) having an area of 645 mm ² was measured. The number of turns of the separator material was also changed (see Table 1 below).

Here, 22 types of test samples were produced, and among them, sample numbers 1 and 2 were positioned as conventional examples. Also, sample numbers 4, 5, 6, 9, 10, 11, 14, 15, 16, 19, 20, 21 are positioned as examples, and sample numbers 3, 7, 8, 12, 13, 17, 18, 22 Was positioned as a comparative example.
[2. Test method]

  Then, the following internal short-circuit test and pulse discharge test were performed on these 22 types of test samples (n = 10).

  In the internal short-circuit test, each test sample was connected to a 3.9Ω load and energized for 5 minutes, measuring the voltage twice a day to obtain a discharge curve indicating the relationship between discharge time and voltage ( Final voltage 0.9V). Moreover, the occurrence rate of internal short circuit was calculated | required by disassembling and investigating the test sample after completion | finish of discharge.

［３．試験結果］ In the pulse discharge test, each test sample was connected to a load and subjected to 1500 mW, 2 seconds and 650 mW, 28 seconds of energization for 10 cycles per hour to obtain the number of sustained cycles (battery life) (end voltage 1.05V). ). The number of sustained cycles for the test sample of sample number 1 (conventional example 1) was 100, and the other test samples were expressed as relative values based on this. The test results are shown in Table 1.

[3. Test results]

  As is apparent from Table 1, in sample number 1 (conventional example 1) in which the number of turns D of the separator material was 3, no internal short circuit occurred, but the distance between the positive and negative electrodes could not be sufficiently shortened. It was disadvantageous. On the other hand, in sample number 2 (conventional example 2) in which the number of turns D of the separator material was 2, as a result of shortening the distance between the positive and negative electrodes, the pulse discharge performance was improved by 20%, while an internal short circuit occurred in half of the samples. It was.

In sample numbers 3 to 7, the air permeability is set to a constant value (C = 4.0 seconds / 100 mL), the number of turns is set to a constant value (D = 2), and the basis weight A and the thickness B are the values of Conventional Example 2. I tried to increase than. However, the value of “basis weight A ÷ thickness B” was made constant. As a result, in Sample No. 3 (Comparative Example 1), the pulse discharge performance was equivalent to that of Conventional Example 2, but an internal short circuit occurred. Sample No. 7 (Comparative Example 2) did not cause an internal short circuit, but the pulse discharge performance was lower than that of Conventional Example 2. On the other hand, in sample numbers 4, 5, and 6 (Examples 1, 2, and 3), although the pulse discharge performance was equivalent to that of Conventional Example 2, no internal short circuit occurred. For Examples 1, 2, and 3, the first shielding index defined by A × B × log C and the second shielding index defined by A × B × log C × D ² are both included in the present invention. It was a numerical value within the preferred range.

In sample numbers 8 to 12, while the basis weight A, the thickness B, and the number of turns D were basically the same as those in Conventional Example 2, only the air permeability C was increased from the value in Conventional Example 2. As a result, in sample number 8 (Comparative Example 3), the pulse discharge performance was equivalent to that of Conventional Example 2, but an internal short circuit occurred. Sample No. 12 (Comparative Example 4) did not cause an internal short circuit, but its pulse discharge performance was lower than that of Conventional Example 2. On the other hand, in sample numbers 9, 10, and 11 (Examples 4, 5, and 6), although the pulse discharge performance was equivalent to that of Conventional Example 2, no internal short circuit occurred. For Examples 4, 5, and 6, the first shielding index defined by A × B × log C and the second shielding index defined by A × B × log C × D ² are both included in the present invention. It was a numerical value within the preferred range.

In sample numbers 13 to 17, the air permeability is set to a constant value (C = 4.0 seconds / 100 mL) and the number of turns D is increased to 3, and the basis weight A and the thickness B are decreased from the values of the conventional example 2. I tried. However, the value of “basis weight A ÷ thickness B” was made constant. As a result, in Sample No. 13 (Comparative Example 5), the pulse discharge performance was equivalent to that of Conventional Example 2, but an internal short circuit occurred. Sample No. 17 (Comparative Example 6) did not cause an internal short circuit, but the pulse discharge performance was lower than that of Conventional Example 2. On the other hand, sample numbers 14, 15, and 16 (Examples 7, 8, and 9) did not cause an internal short circuit although the pulse discharge performance was the same as that of Conventional Example 2. In Examples 7, 8, and 9, the second shielding index defined by A × B × log C × D ² was a numerical value within the preferred range of the present invention.

In sample numbers 18 to 22, the number of turns was set to a constant value (D = 2), and the air permeability C was increased from the value of Conventional Example 2. Note that the basis weight A and the thickness B were set to be smaller than those in Conventional Example 2. As a result, in sample number 18 (Comparative Example 7), the pulse discharge performance was equivalent to that of Conventional Example 2, but an internal short circuit occurred. Sample No. 22 (Comparative Example 8) did not cause an internal short circuit, but its pulse discharge performance was lower than that of Conventional Example 2. On the other hand, in sample numbers 19, 20, and 21 (Examples 10, 11, and 12), although the pulse discharge performance was equivalent to that of Conventional Example 2, no internal short circuit occurred. In Examples 10, 11, and 12, the first shielding index defined by A × B × logC and the second shielding index defined by A × B × logC × D ² are both used in the present invention. It was a numerical value within the preferred range.
In addition, when the discharge curve was drawn about the test sample of the prior art example 1 etc. with an internal short circuit, the voltage fell large before discharge time passed for 4 hours. On the other hand, when the discharge curve is drawn for each of the examples having no internal short circuit, the voltage does not drop greatly even when the discharge time has passed 4 hours, and the battery life is clear as compared with the conventional example 1 and the like. It was long (see graph in FIG. 2).
[4. Conclusion]

  As described above in detail, in the alkaline battery 10 of the present embodiment, paying attention to the basis weight A, the thickness B, the air permeability C, and the average number D, which are a plurality of parameters relating to the shielding properties of the separator 14, The optimization is made in consideration of the interaction of parameters. As a result, it is possible to provide an alkaline battery 10 that has not been realized by individual examination of a plurality of parameters related to the shielding properties of the separator 14, that is, an internal short circuit caused by zinc oxide crystal formation and is excellent in discharge performance. It was possible.

  In addition, you may change embodiment of this invention as follows.

  In the above embodiment, the present invention is embodied in the LR6 type (AA type) cylindrical alkaline battery, but other types of cylindrical alkaline batteries, for example, LR20 type (single type 1), LR14 type (single type) 2 type), LR1 type (single type 5), LR03 type (single type), and the like.

  In the above embodiment, the example in which the number of turns D of the separator material is 2 or 3 is shown, but the present invention is not limited to this, and the number of turns D may be 1.

The schematic sectional drawing which shows the alkaline battery of one Embodiment which actualized this invention. The graph which shows the discharge curve of an alkaline battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Alkaline battery 13 ... Positive electrode mixture which is a positive electrode active material 14 ... Separator for alkaline batteries 15 ... Gel-like negative electrode mixture which is a negative electrode active material

Claims (7)

It consists of a separator material with a basis weight of A (g / m ² ), a thickness of B (mm), and an air permeability of C (seconds / 100 mL), and is disposed between the positive electrode active material and the negative electrode active material. An alkaline battery comprising a separator having an average number of separator materials of D (sheets), wherein the value of A × B × log C × D ² is 14 or more and 22 or less.   The alkaline battery according to claim 1, wherein the separator material is a nonwoven fabric obtained by mixing fibers. The basis weight A is 40 g / m ² or less, the thickness B is 0.120 mm or less, the air permeability C is 5.4 seconds / 100 mL or more and 14 seconds / 100 mL or less, and the average number D is 2 or less. The alkaline battery according to claim 1 or 2. The basis weight A is 36 g / m ² or less, the thickness B is 0.108 mm or less, the air permeability C is 8.0 seconds / 100 mL or more and 26 seconds / 100 mL or less, and the average number D is 2 or less. The alkaline battery according to claim 1 or 2.   5. The method according to claim 1, wherein manganese dioxide or nickel oxyhydroxide is used as the positive electrode active material, zinc alloy powder is used as the negative electrode active material, and an alkaline aqueous solution is used as the electrolytic solution. Alkaline battery. A separator material having a basis weight of A (g / m ² ), a thickness of B (mm), and an air permeability of C (seconds / 100 mL), and the value of A × B × log C is 3.5 or more and 5 A separator material for alkaline batteries, wherein the separator material is .5 or less.   The alkaline battery comprised using the separator material of Claim 6.

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