JP2024035653A - Lead-acid battery - Google Patents

Abstract

To provide a lead-acid battery that exhibits excellent lifetime performance also when used to provide power for an in-vehicle device to use OTA.SOLUTION: The lead-acid battery includes an electric tank having a plurality of cell chambers and an electrode group and an electrolyte contained in each of the plurality of cell chambers. The electrode group has a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material. A ratio Mp/V of a mass Mp (unit: g) of the positive electrode active material contained in the electrode group to a cell volume V (unit: cm3) of the electrode group contained in one of the plurality of cell chambers is 1.05 or more. A ratio Ms/Mp of a mass of sulfuric acid in the electrolyte contained in one of the plurality of cell chambers to the mass Mp (unit: g) of the positive electrode active material is 0.45 or more.SELECTED DRAWING: Figure 3

Description

The present invention relates to lead acid batteries.

Lead-acid batteries are used as batteries for starting automobile engines. Until now, various efforts have been made to improve the life performance of lead-acid batteries for engine starting. For example, Patent Document 1 discloses a technique for improving the life performance of a lead-acid battery for engine starting by incorporating Ketjenblack into the negative electrode material and setting the density of the negative electrode material to 3 g/cm ³ or more.

JP 2019-50229 Publication

In recent years, with the spread of electric vehicles (xEV) such as hybrid cars and electric cars, the importance of auxiliary equipment batteries has increased. In particular, recently, an increasing number of automobiles are equipped with a function to automatically update the software of in-vehicle devices using wireless data transmission and reception technology called OTA (Over The Air). When power is supplied to in-vehicle equipment using OTA, a large amount of power may be temporarily consumed, so lead-acid batteries are required to have performance suitable for such power supply.

Currently, lead-acid batteries for engine starting are being repurposed as batteries for auxiliary equipment, but lead-acid batteries for engine starting are not expected to supply power to in-vehicle equipment that uses OTA, so such power is not available. When used for supply, the lifespan may be shortened.

Accordingly, one aspect of the present invention aims to provide a lead-acid battery that exhibits excellent life performance even when used to supply power when in-vehicle equipment utilizes OTA.

Some aspects of the present invention provide the following [1] to [7].

[1] A lead-acid battery comprising a battery case having a plurality of cell chambers, and an electrode group and an electrolyte solution housed in each of the plurality of cell chambers, the electrode group including a positive electrode containing a positive electrode active material, The mass Mp (unit: cm ) of the positive electrode active material included in the electrode group with respect to the cell volume V (unit: cm ³ ) of the electrode group, which has a negative electrode containing a negative electrode active material and is housed in one of a plurality of cell chambers. :g) ratio Mp/V is 1.05 or more, and the mass Ms( A lead-acid battery having a ratio Ms/Mp (unit: g) of 0.45 or more.
[2] The lead-acid battery according to [1], wherein the ratio Mp/V is 1.20 or more.
[3] The lead acid battery according to [1] or [2], wherein the ratio Mp/V is 1.50 or more.
[4] The lead-acid battery according to any one of [1] to [3], wherein the ratio Ms/Mp is 0.55 or more.
[5] The lead-acid battery according to any one of [1] to [4], wherein the ratio Ms/Mp is 0.70 or more.
[6] The lead-acid battery according to any one of [1] to [5], which is used to supply power to in-vehicle equipment that transmits and receives data via wireless communication.
[7] The lead-acid battery according to any one of [1] to [6], which is used as an auxiliary battery for a hybrid vehicle or an electric vehicle.

According to one aspect of the present invention, it is possible to provide a lead-acid battery that exhibits excellent life performance even when used to supply power when in-vehicle equipment utilizes OTA.

1 is a perspective view showing the overall configuration and internal structure of a lead-acid battery according to an embodiment. FIG. 2 is a perspective view showing a battery case of the lead-acid battery shown in FIG. 1. FIG. FIG. 2 is an exploded perspective view for explaining an electrode group of the lead-acid battery shown in FIG. 1. FIG.

In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum and maximum values, respectively. Furthermore, unless specifically specified, the units of numerical values written before and after "~" are the same. In the numerical ranges described stepwise in this specification, the upper limit or lower limit of the numerical range of one step may be replaced with the upper limit or lower limit of the numerical range of another step. Further, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the Examples. Moreover, the upper limit values and lower limit values described individually can be combined arbitrarily.

Hereinafter, a lead-acid battery according to an embodiment will be described in detail with reference to the drawings as appropriate.

FIG. 1 is a perspective view showing the overall configuration and internal structure of a lead-acid battery according to an embodiment. As shown in FIG. 1, a lead-acid battery 1 according to an embodiment includes a battery case 2 having an open top surface, a lid 3 that closes the opening of the battery case 2, an electrode group 4 housed in the battery case 2, and This is a liquid lead-acid battery comprising an electrolyte (not shown).

The lid 3 includes a positive terminal 5, a negative terminal 6, and a plurality of liquid inlet plugs 7 that respectively close a plurality of liquid inlets provided in the lid 3. The lid 3 is made of polypropylene, for example. The positive electrode terminal 5 is connected to one end of a positive electrode column 18 extending from the lid 3 into the battery case 2 . Similarly, the negative electrode terminal 6 is connected to one end of a negative electrode column (not shown) extending from the lid 3 into the battery case 2 . The electrolyte is, for example, dilute sulfuric acid. In addition to sulfuric acid, the electrolytic solution may contain about 0.01 to 0.1 mol/L of ions (eg, sodium ions).

FIG. 2 is a perspective view showing the battery case 2 of the lead-acid battery 1 shown in FIG. As shown in FIG. 2, the battery case 2 has a hollow, substantially rectangular parallelepiped shape and has an opening on the top surface. That is, the battery case 2 includes a bottom wall having a rectangular planar shape, a pair of side walls (first side walls) 21 erected on the short sides of the bottom wall, and erected on the long sides of the bottom wall. A pair of side walls (second side walls) 22 are provided. The battery case 2 is made of polypropylene, for example.

The inside of the battery case 2 is provided with five partition walls 23 provided substantially parallel to the first side wall 21 . By arranging the five partition walls 23 at predetermined intervals, there are six first to sixth cell chambers 24a to 24f (hereinafter collectively referred to as "cell chambers 24") inside the battery case 2. ) are formed along the second side wall 22 in this order. Each of the cell chambers 24 accommodates an electrode group 4. The electrode group 4 is also called a single cell, and has an electromotive force of 2V, for example.

The inner surface 21a of the first side wall 21 and both surfaces 23a of the partition wall 23 (hereinafter also collectively referred to as "inner wall surfaces 21a, 23a") include a wall extending in a direction perpendicular to the bottom wall (opening surface of the battery case 2). A plurality of ribs 25 are provided. The ribs 25 have a function of appropriately pressurizing (compressing) the electrode group 4 accommodated in each cell chamber 24. In another embodiment, the inner wall surfaces 21a, 23a may not be provided with ribs.

FIG. 3 is an exploded perspective view for explaining the electrode group of the lead-acid battery shown in FIG. As shown in FIG. 3, the electrode group 4 accommodated in one cell chamber 24a of the cell chambers 24 has a plurality of positive electrodes 8, negative electrodes 9, and separators 10 that are approximately connected to the first side wall 21 of the battery case 2. They are stacked vertically. The positive electrode 8 may be a plate-shaped positive electrode (positive electrode plate). The negative electrode 9 may be a plate-shaped negative electrode (negative electrode plate).

The positive electrode 8 includes a positive electrode current collector 11 and a positive electrode active material 12 filled in the positive electrode current collector 11. The positive electrode current collector 11 has a positive electrode lug 11a that protrudes from one end toward the opening side of the battery case 2. The negative electrode 9 includes a negative electrode current collector 13 and a negative electrode active material 14 filled in the negative electrode current collector 13. The negative electrode current collector 13 has a negative electrode lug 13a that protrudes from one end toward the opening side of the battery case 2. In this specification, "positive electrode active material" means the positive electrode minus the positive electrode current collector, and "negative electrode active material" means the negative electrode minus the negative electrode current collector.

The positive electrode current collector 11 and the negative electrode current collector 13 are each made of, for example, a lead-calcium-tin alloy, a lead-calcium alloy, a lead-antimony alloy, or the like. By forming these lead alloys into a lattice shape using a gravity casting method, an expanding method, a punching method, etc., a positive electrode current collector 11 having a positive electrode lug 11a and a negative electrode current collector 13 having a negative electrode lug 13a are obtained. It will be done.

The positive electrode active material 12 contains PbO ₂ as a Pb component, and may further contain a Pb component other than PbO ₂ (for example, PbSO ₄ ) and an additive, if necessary. The additive may be, for example, a fiber (acrylic fiber, polyethylene fiber, polypropylene fiber, polyethylene terephthalate fiber, carbon fiber, etc.). The content of the Pb component in the positive electrode active material 12 may be 90% by mass or more, or 95% by mass or more, and 99.99% by mass or less, based on the total mass of the positive electrode active material 12.

The negative electrode active material 14 contains Pb alone as a Pb component, and may further contain a Pb component other than Pb alone (for example, PbSO ₄ ) and an additive as necessary. Examples of additives include lignin, barium sulfate, fibers (acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, carbon fibers, etc.), and carbon materials (excluding carbon fibers). The content of the Pb component in the negative electrode active material 14 may be 90% by mass or more, or 95% by mass or more, and 99% by mass or less, based on the total mass of the negative electrode active material 14.

The separator 10 is formed into a bag shape and accommodates the negative electrode 9. The separator 10 is made of, for example, polyethylene (PE), polypropylene (PP), or the like. The separator 10 may be a woven fabric, a nonwoven fabric, a porous membrane, or the like made of these materials to which inorganic particles such as SiO ₂ or Al ₂ O ₃ are attached. The thickness of the separator 10 (thickness measured after being developed into a sheet) is, for example, 0.1 to 1.5 mm. Note that the separator 10 may have a shape other than a bag shape (for example, a sheet shape).

Although not shown in FIG. 3, as shown in FIG. 1, the positive electrode ears 11a are collectively welded to each other by a positive electrode strap 15, and the negative electrode ears 13a are collectively welded to each other by a negative electrode strap 16. The positive electrode strap 15 of the electrode group 4 housed in the first cell chamber 24a is connected to the positive electrode column 18 extending from the positive terminal 5 into the battery case 2 via the connecting member 17. The connecting member 17 and the positive pole 18 are each made of lead or a lead alloy.

In one embodiment, in the electrode group 4, a positive electrode 8 and a negative electrode 9 housed in a bag-shaped separator 10 are alternately arranged in this order from the side closer to the inner surface 21a of the first side wall 21 of the battery case 2. The number of positive electrodes 8 and the number of negative electrodes 9 may both be eight.

In the present embodiment, the ratio Mp/V of the mass Mp (unit: g) of the positive electrode active material 12 included in the electrode group 4 to the cell volume V (unit: cm ³ ) of the electrode group 4 accommodated in the cell chamber 24 is 1.05 or more.

Here, the cell volume V means the volume of a single cell constituting the electrode group 4, and in each of the positive electrode 8 (positive electrode current collector 11) and the negative electrode 9 (negative electrode current collector 13), the positive electrode active material 12 and The area of the part (filling part) filled with the negative electrode active material 14 (the area on one side of the two planes parallel to the partition wall 23) S (unit: cm ² ) and the thickness of the electrode group 4 (perpendicular to the partition wall 23) It can be found by multiplying by the length in the direction. Here, the thickness of the electrode group 4 housed in the cell chamber 24 can be considered to be the same as the thickness of the cell chamber 24 (if ribs 25 are provided on the inner wall surfaces 21a, 23a, etc.) whether or not). Therefore, when determining the cell volume V, the thickness Z (unit: cm) of the cell chamber 24 is used. That is, the cell volume V (unit: cm ³ ) is determined by the area S (unit: cm ² ) of the filling portion×thickness Z (unit: cm) of the cell chamber 24 .

The area S of the filled portion is calculated as the average value of all the areas after determining the area of the filled portion in each positive electrode 8 and each negative electrode 9 included in the electrode group 4. For example, when the planar shape of the filled part is approximately rectangular, the area of the filled part in each positive electrode 8 and each negative electrode 9 is calculated by the length X of the filled part (unit: cm) x the width Y of the filled part (unit: cm). Desired. The area of the filled portion in each positive electrode 8 and each negative electrode 9 is calculated as the average value of the areas after calculating the area for each of the two surfaces parallel to the partition wall 23.

The thickness Z (unit: cm) of the cell chamber 24 is the distance between the inner surface 21a of the first side wall 21 and the inner surface 23a of the partition wall 23 at the bottom wall of the cell chamber 24 (the distance between the inner surface 21a of the first side wall 21 and the inner surface 23a of the partition wall 23 (the distance between the cell chambers 24a and 24f located at both ends). ), or the distance between the inner surface 23a of one partition wall 23 and the inner surface 23a of the other partition wall 23 on the bottom wall of the cell chamber 24 (cell chambers 24b, 24c, other than the cell chambers 24a, 24f located at both ends); 24d, 24e).

The mass Mp (unit: g) of the positive electrode active material 12 contained in the electrode group 4 is the mass Mp (unit: g) of the positive electrode 8 measured after taking out the electrode group 4 housed in the cell chamber 24, washing the positive electrode 8 with water, and thoroughly drying it. and the mass of the positive electrode current collector 11 after removing the positive electrode active material 12 from the positive electrode 8. The positive electrode 8 is dried, for example, at 50° C. for 24 hours.

The ratio Mp/V of the mass Mp (unit: g) of the positive electrode active material 12 to the cell volume V (unit: cm ³ ) is determined by the cell volume (unit: cm ³ ) and the mass Mp (unit: g) of the positive electrode active material 12 are determined as described above, the ratio Mp/V is calculated, and the ratio Mp/V is determined as the average value of the ratio Mp/V of all the electrode groups 4.

In the lead-acid battery 1 of this embodiment, the above ratio Mp/V is 1.05 or more, which means that a relatively large amount of the positive electrode active material 12 is filled in the portion constituting the electrode group 4 (single cell). It means to do. As shown in Examples and Comparative Examples to be described later, if the ratio Mp/V is, for example, 1.00 or more, even if a large amount of positive electrode active material 12 is filled, the lead-acid battery when used to start an engine is There is no difference in lifespan. In contrast, the present inventors have discovered that the lifespan of lead-acid batteries when used to supply power when in-vehicle equipment uses OTA is affected by the ratio Mp/V, and that the ratio Mp It has been found that when /V is 1.05 or more, a lead acid battery having an excellent life span can be obtained.

The above ratio Mp/V is 1.10 or more, 1.15 or more, 1. It may be 20 or more, 1.25 or more, 1.30 or more, 1.35 or more, 1.40 or more, 1.45 or more, or 1.50 or more. The above ratio Mp/V may be 1.80 or less, 1.75 or less, 1.70 or less, 1.65 or less, 1.60 or less, 1.55 or less, or 1.50 or less. The value of the above ratio Mp/V can be determined, for example, by increasing the number of positive electrodes 8 included in the electrode group 4, or by increasing the density or thickness of the positive electrode active material 12 included in the positive electrode 8 (the length in the thickness direction of the electrode group 4). ) can be made larger.

The cell volume V of the electrode group 4 can be changed depending on the battery size, and may be, for example, 220 to 390 cm ³ , 320 to 570 cm ³ , or 370 to 670 cm ³ .

In the lead-acid battery 1 of the present embodiment, in addition to the above-mentioned ratio Mp/V being 1.05 or more, the ratio Mp/V of the positive electrode active material is accommodated in one of the plurality of cell chambers with respect to the mass Mp (unit: g). The ratio Ms/Mp of the mass Ms (unit: g) of sulfuric acid in the electrolytic solution was 0.45 or more. The mass Mp (unit: g) of the positive electrode active material is as explained above.

The mass Ms (unit: g) of sulfuric acid in the electrolytic solution contained in one of the cell chambers is determined as follows.
First, the lead acid battery is charged until it is fully charged, and then the specific gravity at 20° C. of the electrolyte contained in one of the cell chambers of the fully charged lead acid battery is measured. Next, using a calibration curve created from the relationship between specific gravity and concentration (unit: mass %) described in the Battery Handbook (Publisher: Ohmsha, Electrochemical Society of Japan Battery Technical Committee (edited)) 3-36, As shown in Table 1 below, the electrolytic concentration (unit: mass %) can be calculated from the measured specific gravity of the electrolytic solution at 20°C. The mass Ms (unit: g) of sulfuric acid is determined by the mass (unit: g) of the electrolytic solution accommodated in one of the cell chambers x the calculated concentration (unit: mass %)/100.

The ratio Ms/Mp of the mass Ms (unit: g) of sulfuric acid to the mass Mp (unit: g) of the positive electrode active material is the mass Mp (unit: g) of the positive electrode active material 12 included in the electrode group 4 for each cell chamber 24. :g), and the mass Ms (unit: g) of sulfuric acid in the electrolytic solution contained in each cell chamber 24 is determined as above, and the ratio Ms/Mp is calculated, and the ratio Ms in all cell chambers 24 is calculated. /Mp.

In the lead-acid battery 1 of this embodiment, the ratio Ms/Mp of the mass Ms (unit: g) of sulfuric acid to the mass Mp (unit: g) of the positive electrode active material is 0.45 or more; This means that the amount of sulfuric acid in the electrolytic solution is relatively large relative to the amount of positive electrode active material 12 contained in the (single cell). As shown in the Examples and Comparative Examples described below, if the ratio Ms/Mp is, for example, 0.41 or more, even if the amount of sulfuric acid is increased, the life of the lead-acid battery when used to start an engine will be shortened. makes no difference. In contrast, the present inventors discovered that the life of a lead-acid battery when used to supply power when an in-vehicle device uses OTA is affected by the ratio Ms/Mp, and that the ratio Ms/Mp It has been found that when /Mp is 0.45 or more, a lead-acid battery having an excellent service life can be obtained.

The above ratio Ms/Mp is 0.49 or more, 0.55 or more, and 0.49 or more, 0.55 or more, and 0.49 or more, 0.55 or more, from the viewpoint of further improving the life of the lead-acid battery when used to supply power when in-vehicle equipment uses OTA. It may be 60 or more, 0.65 or more, 0.70 or more, 0.75 or more, or 0.80 or more. The above ratio Ms/Mp may be 1.00 or less, 0.95 or less, 0.90 or less, 0.85 or less, or 0.80 or less. The value of the ratio Ms/Mp can be increased by, for example, increasing the volume of the electrolytic solution accommodated in one cell chamber, increasing the concentration of sulfuric acid in the electrolytic solution, or the like.

The ratio Mp/Mn of the mass Mp (unit: g) of the positive electrode active material 12 included in the electrode group 4 to the mass Mn (unit: g) of the negative electrode active material 14 included in the electrode group 4 is 1.00 or more, It may be 1.05 or more, 1.10 or more, 1.15 or more, or 1.20 or more, and may be 1.85 or less, 1.80 or less, 1.75 or less, or 1.70 or less. . The mass Mn (unit: g) of the negative electrode active material 14 contained in the electrode group 4 is the negative electrode 9 measured after taking out the electrode group 4 accommodated in the cell chamber 24, washing the negative electrode 9 with water, and thoroughly drying it. and the mass of the negative electrode current collector 13 after removing the negative electrode active material 14 from the negative electrode 9. The negative electrode 9 is dried, for example, at 50° C. for 24 hours.

The lead-acid battery 1 described above is suitably used to supply power to in-vehicle equipment that transmits and receives data via wireless communication. The lead acid battery 1 is also suitably used as an auxiliary battery for an automobile. In addition to vehicles without an internal combustion engine, such vehicles include vehicles equipped with an internal combustion engine, a storage battery that supplies power to start the internal combustion engine, and a lead-acid battery that supplies power required while the engine is parked. Can be mentioned. Examples of such vehicles include electric vehicles such as hybrid vehicles and electric vehicles. The lead-acid battery 1 is particularly suitably used as an auxiliary battery for electric vehicles (particularly hybrid vehicles and electric vehicles).

The lead-acid battery 1 may be used to supply the power necessary to operate, for example, the function of automatically opening and closing the door, the function of automatically starting the car navigation power supply, etc. while the car is parked as described above. good.

The lead-acid battery 1 is manufactured by a manufacturing method that includes, for example, an electrode manufacturing process for obtaining electrodes (a negative electrode and a positive electrode), and an assembly process for assembling constituent members including the electrodes to obtain the lead-acid battery 1. The method for manufacturing the lead-acid battery 1 includes a step of chemically forming an unformed negative electrode and a positive electrode (chemical formation step). The chemical conversion process may be performed in the electrode manufacturing process, or may be performed in the assembly process. The electrode manufacturing process and assembly process will be explained below.

The electrode manufacturing process includes a negative electrode manufacturing process and a positive electrode manufacturing process.

In the negative electrode manufacturing process, for example, a negative electrode current collector holds a paste-like negative electrode active material (negative electrode active material paste), and then is aged and dried to obtain an unformed negative electrode. The negative electrode active material paste contains, for example, lead powder, additives, and sulfuric acid (for example, dilute sulfuric acid). The negative electrode active material paste is obtained, for example, by mixing lead powder and additives to obtain a mixture, and then adding a solvent and sulfuric acid to this mixture and kneading the mixture. The water content in the negative electrode active material paste may be, for example, 5% by mass or more, 10% by mass or more, or 15% by mass or more, and 30% by mass or less, 25% by mass or less, or 20% by mass or less.

In the positive electrode manufacturing process, for example, a positive electrode current collector holds a paste-like positive electrode active material (positive electrode active material paste), and then is aged and dried to obtain an unformed positive electrode. The positive electrode active material paste contains, for example, lead powder, additives, and sulfuric acid (for example, dilute sulfuric acid). The positive electrode active material paste can be obtained, for example, by mixing lead powder and additives to obtain a mixture, and then adding a solvent and sulfuric acid to this mixture and kneading the mixture. The water content in the positive electrode active material paste may be, for example, 5% by mass or more, 10% by mass or more, or 15% by mass or more, and 30% by mass or less, 25% by mass or less, or 20% by mass or less.

In the assembly process, for example, the obtained unformed positive and negative electrodes are stacked with a separator in between, and the current collecting parts of the electrodes of the same polarity are welded with a strap to obtain an unformed electrode group. After accommodating this electrode group in each cell in the battery case and connecting the negative electrode strap and positive electrode strap of the electrode group in adjacent cell chambers by the inter-cell connection portion penetrating the partition wall separating the cell chambers, A crude lead-acid battery is created by attaching a lid to the top of the battery case. Next, dilute sulfuric acid is poured into an unformed lead-acid battery and DC current is applied to form the battery. Subsequently, the lead acid battery 1 is obtained by adjusting the specific gravity (20° C.) of the sulfuric acid after chemical formation to an appropriate specific gravity of the electrolytic solution.

The specific gravity (20° C.) of sulfuric acid used for chemical formation may be 1.15 to 1.25. The specific gravity (20° C.) of sulfuric acid after chemical conversion is preferably 1.25 to 1.33, more preferably 1.26 to 1.30. The chemical formation conditions and the specific gravity of sulfuric acid can be adjusted depending on the size of the electrode. The chemical conversion treatment may be performed in the assembly process or in the electrode manufacturing process (tank chemical conversion).

Hereinafter, the present invention will be specifically explained with reference to Examples. However, the present invention is not limited to the following examples.

<Comparative example 1>
(Preparation of unformed positive electrode plate)
Lead powder and red lead (Pb ₃ O ₄ ) were prepared as the Pb component (lead powder: red lead = 96:4 (mass ratio)). The Pb component, 0.07% by mass of reinforcing short fibers (acrylic fibers) based on the total mass of the Pb component, and water were mixed and kneaded. Subsequently, dilute sulfuric acid (specific gravity: 1.280) was added little by little and kneaded to prepare a positive electrode active material paste. This positive electrode active material paste was filled into an expanded positive electrode current collector produced by expanding a rolled sheet made of a lead alloy. Next, the positive electrode active material paste was aged for 24 hours in an atmosphere at a temperature of 50° C. and a humidity of 98%, and then dried at a temperature of 60° C. for 24 hours or more to obtain an unformed positive electrode plate.

(Preparation of unformed negative electrode plate)
Lead powder was prepared as a Pb component. A mixture of 0.2 parts by mass of lignin powder, 0.1 parts by mass of acrylic fibers, 1.0 parts by mass of barium sulfate, and 0.2 parts by mass of carbon powder was added to 100 parts by mass of Pb component (lead powder). , dry mixed. Next, water was added to this mixture and kneaded, and then further kneaded while adding dilute sulfuric acid having a specific gravity of 1.280 little by little to prepare a negative electrode active material paste. This negative electrode active material paste was filled into an expanded negative electrode current collector produced by expanding a rolled sheet made of a lead alloy. Next, the negative electrode active material paste was aged for 24 hours in an atmosphere with a temperature of 50° C. and a humidity of 98%, and then dried at a temperature of 50° C. for 16 hours to obtain an unformed negative electrode plate.

(Assembling lead-acid battery for evaluation)
An unformed negative electrode plate was inserted into a bag-shaped polyethylene separator (thickness: 0.75 mm). Next, eight unformed positive electrode plates and eight unformed negative electrode plates inserted into the bag-shaped separator were alternately laminated. Subsequently, the ears of the electrodes of the same polarity were welded together using a cast-on strap (COS) method to produce an electrode group. Six of these electrode groups were prepared, and each was inserted into a battery case having six cell chambers. Next, after connecting the negative electrode strap and positive electrode strap of the electrode group between cells, a 12V battery (corresponding to B24 size according to JIS D 5301) was assembled by thermally welding the lid to the top of the battery case. Thereafter, an electrolytic solution (sodium ion concentration: 0.05 mol/L) prepared by adding an aqueous sodium sulfate solution to dilute sulfuric acid was injected into each cell of the battery, and the cells were placed in a water bath at 40° C. and allowed to stand for 1 hour. Thereafter, chemical conversion was performed at a constant current of 17 A for 18 hours to obtain a lead acid battery for evaluation. Note that the specific gravity of the electrolyte solution (sulfuric acid solution) after chemical formation was adjusted to 1.28 (20° C.).

The cell volume V of the electrode group obtained through the above steps is 376 cm ³ , the mass Mp of the positive electrode active material contained in the electrode group is 376 g, and the mass Ms of sulfuric acid in the electrolyte solution accommodated in one cell chamber is 184 g. there were. Table 2 shows the values of Mp/V and Ms/Mp.

<Comparative Example 2 and Examples 1 to 25>
In Comparative Example 2 and Examples 1 to 25, Mp/V and Ms/Mp were changed by changing the number of positive electrode plates and negative electrode plates in the electrode group, the density of the positive electrode active material in the positive electrode plate, and the injection amount of electrolyte. Lead-acid batteries for evaluation with values changed as shown in Table 2 were obtained.

In Comparative Examples 1 to 2 and Examples 1 to 25, the ratio Mp/Mn of the mass Mp of the positive electrode active material included in the electrode group to the mass Mn of the negative electrode active material included in the electrode group in the electrode group was 1. It was within the range of 23 to 1.68.

<Evaluation>
(Lifetime test for power supply application when using OTA)
For the lead-acid battery for evaluation in each experimental example, the following (I) was repeatedly performed in a temperature environment of 25°C, and the number of cycles (repetitive The number of times) was measured. The evaluation was a relative evaluation in which the number of cycles of the evaluation lead acid battery of Comparative Example 1 was set to 100. Through this evaluation, it is possible to evaluate the lifespan of the lead-acid battery when it is used to supply power when in-vehicle equipment uses OTA. The results are shown in Table 2.
(I): Discharging under condition (1) below and charging under condition (2) below are repeated three times each in this order, then discharging under condition (3) below and charging under condition (4) below. and in this order.
Condition (1): Discharge current = 25 A, discharge time = 240 seconds Condition (2): Charging voltage = 14.8 V, charging time = 600 seconds Condition (3): Discharge current = 25 A, discharge time = 600 seconds Condition (4) ): Charging voltage = 14.8V, charging time = 1500 seconds

(Life test for engine starting applications)
For the evaluation lead-acid batteries of each comparative example and example, the following (II) was repeatedly performed in a temperature environment of 40°C until the final voltage during continuous discharge at the rated cold cranking current reached 7.2V. The number of cycles was measured. The evaluation was a relative evaluation in which the number of cycles of the evaluation lead acid battery of Comparative Example 1 was set to 100. This evaluation makes it possible to evaluate the lifespan of a lead acid battery when used to start an engine. The results are shown in Table 2.
(III): After repeating discharging under the above condition (1) and charging under the above condition (2) in this order 480 times, and leaving it for 56 hours, Perform continuous discharge for seconds.

DESCRIPTION OF SYMBOLS 1... Lead-acid battery, 2... Battery container, 4... Electrode group, 8... Positive electrode, 9... Negative electrode, 12... Positive electrode active material, 14... Negative electrode active material, 24... Cell chamber.

Claims (7)

A battery case having multiple cell chambers;
an electrode group and an electrolytic solution housed in each of the plurality of cell chambers;
A lead-acid battery comprising:
The electrode group is
a positive electrode containing a positive electrode active material;
a negative electrode containing a negative electrode active material;
has
a ratio Mp/V of the mass Mp (unit: g) of the positive electrode active material included in the electrode group to the cell volume V (unit: cm ³ ) of the electrode group accommodated in one of the plurality of cell chambers; is 1.05 or more,
The ratio Ms/Mp of the mass Ms (unit: g) of sulfuric acid in the electrolytic solution accommodated in one of the plurality of cell chambers to the mass Mp (unit: g) of the positive electrode active material is 0.45. That's it for lead acid batteries. The lead acid battery according to claim 1, wherein the ratio Mp/V is 1.20 or more. The lead acid battery according to claim 1, wherein the ratio Mp/V is 1.50 or more. The lead-acid battery according to claim 1, wherein the ratio Ms/Mp is 0.55 or more. The lead-acid battery according to claim 1, wherein the ratio Ms/Mp is 0.70 or more. The lead-acid battery according to any one of claims 1 to 5, which is used to supply power to in-vehicle equipment that transmits and receives data via wireless communication. The lead-acid battery according to any one of claims 1 to 5, which is used as an auxiliary battery for a hybrid vehicle or an electric vehicle.

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