JP7113037B2 - liquid lead acid battery - Google Patents

Description

The present invention relates to flooded lead-acid batteries.

BACKGROUND ART In recent years, with the seriousness of environmental problems, exhaust gas regulations for automobiles and the like have become stricter all over the world. Automakers have developed various environmental technologies to comply with these regulations. As an environmental technology, an idling stop system (hereinafter referred to as "ISS") that temporarily stops the engine when the vehicle is stopped is known. An internal combustion vehicle equipped with an ISS (hereinafter referred to as an "ISS vehicle") can suppress fuel consumption due to idling when the vehicle is stopped at a traffic light or the like, thereby improving fuel efficiency and further reducing the amount of exhaust gas.

A lead-acid battery for an ISS vehicle is repeatedly charged and discharged in a partial state of charge (also referred to as "PSOC"), which is not a fully charged state, because the engine repeatedly stops and starts. be If the charge rate of the lead-acid battery of the ISS vehicle is higher than 90%, the charge acceptance becomes low and the utilization efficiency of regenerative energy decreases. is preferred.

Electrolyte stratification, which is one of the causes of deterioration of flooded lead-acid batteries, is a phenomenon in which there is a difference in the concentration of the electrolyte between the upper and lower parts of the container, maintaining a partially charged state of 80% to 90%. It is likely to occur when using a lead-acid battery that is controlled to do so. In the upper part where the concentration of the electrolyte is low, dendrites of metallic lead are deposited and grown on the surface of the negative electrode plate, and internal short circuits are likely to occur. On the other hand, in the lower portion where the concentration of the electrolyte is high, the high concentration of the electrolyte tends to cause sulfation in which the non-conductive lead sulfate enlarges on the surface of the negative electrode plate.

When sulfation occurs, the discharge of sulfuric acid from the negative electrode active material is suppressed, so that the charge acceptability of the lower portion of the negative electrode plate decreases. When the charge acceptability of the lower part of the negative plate decreases, the charge-discharge reaction proceeds mainly in the upper part of the negative plate, so the positive electrode active material on the upper part of the positive plate facing the upper part of the negative plate softens and the current collector Corrosion of the substrate made of the lead alloy progresses, and the life of the lead-acid battery comes to an early end.
As for the technology for suppressing the stratification of the electrolytic solution, for example, the technology described in Patent Literature 1 can be cited.

In Patent Document 1, in order to more effectively utilize the agitating action of the electrolyte solution by the gas generated during charging to suppress stratification, apart from the accommodation space for accommodating the electrode plate group, an upper part of the accommodation space and a It is described that a communication channel communicating with the lower portion is provided. As a result, during charging, an upward flow of the electrolytic solution is generated in the housing space as the gas generated by the electrode plate assembly rises, and a corresponding downward flow is generated in the communication channel. Therefore, it is described that the convection of the electrolytic solution is effectively generated in the container, thereby enhancing the stirring action of the electrolytic solution and suppressing stratification.

On the other hand, a flooded lead-acid battery includes a positive electrode plate in which a positive current collector holds a positive electrode mixture, and a negative electrode plate in which a negative electrode current collector holds a negative electrode mixture. The positive electrode current collector and the negative electrode current collector each have a rectangular grid-like substrate and ears continuous with the grid-like substrate, as shown in FIG. 1 of Patent Document 2, for example. The lattice-like substrate has upper ribs along one side of a rectangle forming the lattice-like substrate, and a plurality of middle ribs connected to the upper bones and present below the upper bones. Ears protrude upward from the center of one side of the upper bone.
However, Patent Literatures 1 and 2 do not describe the relationship between the potential distribution of the electrode plates during charging and discharging and the stirring action of the electrolytic solution.

JP 2015-176659 A Japanese Patent No. 3452171

An object of the present invention is to provide a novel flooded lead-acid battery in which even when used in a partially charged state, stratification of the electrolytic solution is suppressed by the agitating action of gas generated during charging.

In order to solve the above problems, the liquid lead-acid battery of the first aspect of the present invention has the following configurations (1) to (4).
(1) A liquid lead-acid battery comprising a positive electrode plate having a positive electrode current collector and a positive electrode mixture. The positive electrode current collector has a rectangular grid-like substrate and ears continuous with the grid-like substrate, and the grid-like substrate holds a positive electrode mixture. The lattice-like substrate has upper ribs along one side of a rectangle forming the lattice-like substrate, and a plurality of middle ribs connected to the upper bones and present below the upper bones. Ears protrude upward from the center of one side of the upper bone.

(2) Of the divided bodies produced by cutting the positive electrode current collector along the diagonal line passing through the corners on one side of the rectangle forming the grid-like substrate, the divided bodies in which the ears are present are the upper bones of the ears. It is divided into a first portion and a second portion by a reference line K passing through a center point P on the boundary of the upper bone and perpendicular to the upper bone, and the first portion has a larger area than the second portion.

(3) Each resistance value Rn between each cutting plane Cn of the plurality of midribs and the center point P in the first portion is represented by the y-coordinate on a coordinate plane in which both the x-axis and the y-axis are linear scales, All the plots made by using each distance Xn between the center point of each cutting plane Cn and the center point P as the x coordinate can be approximated to two straight lines with different slopes with x=H as the intersection point, and x<H. A ratio A/B between the average value A of each resistance value Rn at the distance Xn and the average value B of each resistance value Rn at each distance Xn satisfying x≧H is 0.35 or more and 0.55 or less be.
It should be noted that the above-mentioned "can be approximated to a straight line" means that the absolute value |ρ| Also, "two straight lines with different slopes" means that the ratio (a1/a2) of the slopes a1 and a2 (a1>a2) of the two straight lines is 1.3 or more.

(4) Mass a of the segment left after cutting along the boundary line where the segmented body where the ear of the positive electrode current collector exists (hereinafter also simply referred to as "the mass a of the segmented body where the ear exists") The ratio a/b of the positive electrode current collector to the mass b of the divided body without the ears of the positive electrode current collector is 1.1 or more and 1.9 or less.
Note that the mass a of the divided body where the tabs are present refers to the mass of the grid-like substrate excluding the mass of the tabs of the positive electrode current collector.

According to the present invention, it is possible to provide a novel flooded lead-acid battery in which even when used in a partially charged state, stratification of the electrolytic solution is suppressed by the agitating action of gas generated during charging.

FIG. 3 is a front view showing a positive current collector that constitutes a positive electrode plate of the liquid lead-acid battery of the first embodiment; FIG. 2 is a front view showing a divided body having ears, which is produced by cutting the positive electrode current collector of FIG. 1 along a diagonal line passing through one corner of a rectangular substrate forming a lattice substrate. FIG. 4 is a front view showing a positive electrode current collector that constitutes a positive electrode plate of the liquid lead-acid battery of the second embodiment. FIG. 3 is a front view showing a divided body having ears, which is produced by cutting the positive electrode current collector of FIG. Each resistance value Rn between each cut surface Cn of a plurality of backbones and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 1 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of backbones and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 2 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of midribs and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 3 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of backbones and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 4 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of backbones and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 5 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of midribs and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 6 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. Each resistance value Rn between each cut surface Cn of a plurality of backbones and the center point P of the ear in the first portion of the positive electrode current collector obtained for sample No. 7 prepared in the example, and , and distances Xn between the center point of each cut plane Cn and the center point P of the ear. 1 is a graph showing a charge/discharge pattern of one cycle in a life test conducted in Examples.

Embodiments of the present invention will be described below, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferred limitations are made for implementing the present invention, but the limitations are not essential to the present invention.
[Configuration of liquid lead-acid battery of first embodiment and second embodiment]
The flooded lead-acid batteries of the first embodiment and the second embodiment have a monoblock type container, a lid, and six electrode plate groups. The container is partitioned into six cell chambers by partition walls. Six cell chambers are arranged along the longitudinal direction of the container. One electrode plate group is arranged in each cell chamber. An electrolyte is injected into each cell chamber.

Each electrode plate group has a laminate including a plurality of positive electrode plates and negative electrode plates alternately arranged, and a separator disposed between the positive electrode plates and the negative electrode plates.
The positive electrode plate has a positive electrode current collector and a positive electrode mixture (a mixture containing a positive electrode active material). The positive electrode current collector has a rectangular grid-like substrate and ears continuous with the grid-like substrate, and the grid-like substrate holds a positive electrode mixture. Further, in the present invention, the ratio a/b between the mass a of the positive electrode current collector segment having ears and the mass b of the positive electrode current collector segment having no ears is 1.1 or more and 1.9. It is below. The negative electrode plate has a negative electrode current collector and a negative electrode mixture (a mixture containing a negative electrode active material). The negative electrode current collector has a rectangular grid-like substrate and ears continuous with the grid-like substrate, and the grid-like substrate holds the negative electrode mixture. The plurality of positive electrode plates and negative electrode plates are alternately arranged with separators interposed therebetween. The number M _n of the negative electrode plates constituting the laminate is one more than the number M _p of the positive electrode plates.

The negative electrode plate is housed in a bag-like separator. By alternately stacking the bag-like separators containing the negative electrode plates and the positive electrode plates, the separators are arranged between the positive electrode plates and the negative electrode plates. In addition, the positive electrode plate may be accommodated in the bag-like separator and alternately stacked with the negative electrode plate.
Each electrode plate group includes a positive electrode strap and a negative electrode strap that connect the plurality of positive electrode plates and the negative electrode plates that constitute the laminate at different positions in the width direction, and positive electrode intermediate pole columns that rise from the positive electrode strap and the negative electrode strap, respectively. and an intermediate negative electrode column, and a positive electrode column and a negative electrode column that serve as external terminals.

The positive strap and the negative strap connect and fix the tabs of the plurality of positive plates and negative plates, respectively. The intermediate positive poles and the intermediate negative poles of the adjacent cell chambers are resistance-welded to electrically connect the adjacent cells in series.
The positive electrode poles and the negative electrode poles are formed via the small piece portions on the positive electrode straps and the negative electrode straps arranged in the cell chambers at both ends in the cell arrangement direction.

[Positive electrode current collector of the first embodiment]
As shown in FIG. 1, the positive electrode current collector 1 of the first embodiment has a rectangular grid-like substrate 11 and ears 12 continuous with the grid-like substrate 11, and the grid-like substrate 11 holds a positive electrode mixture. It is The lattice-like substrate 11 has an upper rib 111 along one side of a rectangle forming the lattice-like substrate 11 and a plurality of middle ribs 112 connected to the upper bone 111 and present below the upper bone 111 . The ear 12 protrudes upward from a position shifted to one side (right side in FIG. 1) from the center of one side of the upper bone 111 .

FIG. 2 shows a divided body having ears among the divided bodies obtained by cutting the positive electrode current collector 1 along the diagonal line T passing through the right (one side) corner of the rectangle forming the lattice substrate 11. show. The divided body 2 is divided into a first portion 21 and a second portion 22 by a reference line K passing through the center point P on the boundary line L between the ear 12 and the upper bone 111 and perpendicular to the upper bone 111, The first portion 21 has a larger area than the second portion 22 .

The first portion 21 has cut surfaces of thirteen midribs 112 . Each resistance value R1 to R13 between each of the 13 cutting planes C1 to C13 and the center point P is represented as the y coordinate and the center of each cutting plane C1 to C13 on a coordinate plane in which both the x-axis and the y-axis are linear scales. If the respective distances X1 to X13 between the point and the center point P are plotted as x-coordinates, all plots can be approximated by two straight lines with different slopes with x=H as the intersection point. The ratio A/B between the average value A of each resistance value Rn at each distance Xn satisfying x<H and the average value B of each resistance value Rn at each distance Xn satisfying x≧H is 0.35. 0.55 or less.

For example, when dimension S1 = 115.0 mm, dimension S2 = 110.0 mm, dimension S3 = 100.0 mm, and dimension S4 = 45.0 mm, the thickness of the central rib 112 (cross-sectional area perpendicular to the longitudinal direction) is It is the same and is 0.85 mm or more and 1.00 mm or less.
The positive electrode current collector 1 can be obtained by an ordinary method such as a punching method, an expanding method, or a gravity casting method. In addition, the ratio a/b between the mass a of the positive electrode current collector segment having the positive electrode current collector ears and the mass b of the positive electrode current collector segment having no ears is set to 1.1 or more and 1.9 or less. can be appropriately adjusted by changing the balance of the width, thickness, etc. of the positive electrode current collector.

[Positive electrode current collector of the second embodiment]
As shown in FIG. 3, the positive electrode current collector 1A of the second embodiment has a rectangular lattice-like substrate 11A and ears 12 continuous to the lattice-like substrate 11A. It is The lattice-like substrate 11A has an upper rib 111 along one side of a rectangle forming the lattice-like substrate 11A and a plurality of middle ribs connected to the upper bone 111 and present below the upper bone 111 . The thickness of the middle rib changes at the middle position in the vertical direction, and the middle rib 112a above the middle position (upper bone 111 side) is thinner than the middle bone 112b below the middle position.

The ear 12 protrudes upward from a position shifted to one side (right side in FIG. 3) from the center of one side of the upper bone 111 .
FIG. 4 shows a split body having ears among the split bodies produced by cutting the positive electrode current collector 1A along the diagonal line T passing through the right (one side) corner of the rectangle forming the lattice substrate 11A. show. The divided body 2A is divided into a first portion 21A and a second portion 22A by a reference line K passing through the center point P on the boundary line L between the upper bone 111 of the ear 12 and perpendicular to the upper bone 111, The first portion 21A has a larger area than the second portion 22A.

The first portion 21A has cut surfaces of 13 mid-bones. Cutting planes C1 to C5 are cutting planes of the middle rib 112a, and cutting planes C6 to C13 are cutting planes of the middle rib 112b. Each resistance value R1 to R13 between each of the 13 cutting planes C1 to C13 and the center point P is represented as the y coordinate and the center of each cutting plane C1 to C13 on a coordinate plane in which both the x-axis and the y-axis are linear scales. If the respective distances X1 to X13 between the point and the center point P are plotted as x-coordinates, all plots can be approximated by two straight lines with different slopes with x=H as the intersection point. The ratio A/B between the average value A of each resistance value Rn at each distance Xn satisfying x<H and the average value B of each resistance value Rn at each distance Xn satisfying x≧H is 0.35. 0.55 or less.

For example, when the dimension S1=115.0 mm, the dimension S2=110.0 mm, the dimension S3=100.0 mm, and the dimension S4=45.0 mm, the thickness (cross-sectional area perpendicular to the longitudinal direction) of the central rib 112a is 0.0 mm. The thickness is 75 mm or more and 0.85 mm or less, and the thickness of the middle rib 112b is 1.15 mm or more and 1.25 mm or less.
The positive electrode current collector 1 can be obtained by an ordinary method such as a punching method, an expanding method, or a gravity casting method. In addition, the ratio a/b between the mass a of the positive electrode current collector segment having the positive electrode current collector ears and the mass b of the positive electrode current collector segment having no ears is set to 1.1 or more and 1.9 or less. can be appropriately adjusted by changing the balance of the width, thickness, etc. of the positive electrode current collector.

[action, effect]
As the ratio A/B of the positive electrode current collector of the flooded lead-acid battery is smaller, the lower portion of the positive electrode plate is more likely to polarize than the upper portion during charging. Even if it is, the stirring effect|action of electrolyte solution is obtained. However, when the ratio A/B is less than 0.35, the resistance value of the path from the bottom of the positive electrode current collector to the ear is significantly higher than the resistance value of the path from the top to the ear. Charging and discharging reactions become difficult to progress. Therefore, the amount of gas generated from the bottom becomes insufficient to obtain the electrolyte solution stirring action in the partially charged state.

In a flooded lead-acid battery in which the ratio A/B of the positive electrode current collector is greater than 0.55, the charging and discharging reaction is difficult to progress in the entire positive electrode plate, so the amount of gas generated is the electrolyte solution stirring action in the partially charged state. is insufficient to obtain
The ratio A/B of the positive electrode current collector 1 of the first embodiment and the positive electrode current collector 1A of the second embodiment is in the range of 0.35 or more and 0.55 or less. In the liquid type lead-acid battery of the above embodiment, the charging and discharging reactions occur uniformly over the entire positive electrode plate, so the amount of gas generated from the lower part is sufficient to obtain the stirring action of the electrolyte solution in the partially charged state. . Therefore, according to the flooded lead-acid batteries of the first embodiment and the second embodiment, when used in a partially charged state, stratification of the electrolytic solution is suppressed, and the service life can be lengthened.

Furthermore, in the liquid-type lead-acid battery using the positive electrode current collector 1 of the first embodiment and the liquid-type lead-acid battery using the positive electrode current collector 1A of the second embodiment, the divided body in which the ears of the positive electrode current collector are present The ratio a/b between the mass a of the positive electrode current collector and the mass b of the divided body without ears of the positive electrode current collector is preferably 1.1 or more and 1.9 or less, and the potential of the positive electrode current collector under this condition Lifetime can be lengthened by improved distribution and further suppression of stratification of the electrolyte. When the ratio a/b of the mass a of the segment having the positive electrode current collector ears and the mass b of the segment not having the positive electrode current collector ears is less than 1.1, the potential distribution is improved. The effect of suppressing stratification cannot be obtained. Further, when the ratio a/b of the mass a of the positive electrode current collector segment having the ears and the mass b of the positive electrode current collector segment not having the ears exceeds 1.9, the potential distribution becomes excessive. As a result of the improvement, the water loss of the electrolyte increases, and the service life performance decreases.

[Method Aspect]
A second aspect of the present invention includes a method of designing a positive electrode current collector that constitutes a positive electrode plate (after chemical conversion) of a flooded lead-acid battery. This design method has the following configurations (a) to (c).
(a) The positive electrode current collector has a rectangular grid-like substrate and ears continuous with the grid-like substrate, the grid-like substrate holds the positive electrode mixture, and the grid-like substrate is an upper rib along one side of the rectangle. and a plurality of middle bones that are connected to the upper bone and exist below the upper bone, and the ear protrudes upward from a position shifted to one side from the center of one side of the upper bone.
(b) Among the divided bodies produced by cutting the positive electrode current collector along the diagonal line passing through one corner of the rectangle, the divided body where the ear exists is placed at the center point P on the boundary line with the upper bone of the ear. A reference line perpendicular to the thoracic superior bone separates the first and second portions.
(c) on a coordinate plane where both the x-axis and the y-axis are linear scales, between each cutting plane Cn of the plurality of midribs and the center point P in the first portion having a larger area than the second portion; Each resistance value Rn is the y-coordinate, and each distance Xn between the center point and the center point P of each cut surface Cn is the x-coordinate. The ratio A/B between the average value A of each resistance value Rn at each distance Xn satisfying x<H and the average value B of each resistance value Rn at each distance Xn satisfying x≧H, which can be approximated, is It is made to be 0.35 or more and 0.55 or less.

[Preparation of test battery]
Lead-acid batteries of Samples No. 1 to No. 7 were produced as lead-acid batteries having the same structure as the lead-acid batteries of the embodiment.
The lead-acid batteries of Samples No. 1 to No. 7 are M42-type flooded lead-acid batteries for idling stop, and differ in the configuration of the grid-like substrate of the positive electrode current collector. have
<Sample No.1>
The lead-acid battery of sample No. 1 has a positive electrode current collector 1 having the shape shown in FIG. 0 mm, and the thickness of the middle rib 112 (cross-sectional area perpendicular to the longitudinal direction) is 1.05 mm.

First, a step of punching a strip-shaped lead alloy sheet (having a size corresponding to a plurality of positive electrode current collectors 1), a step of filling the grid-like substrate 11 with the positive electrode active material paste, a preheating drying step, an aging drying step, and By performing the cutting step, a positive electrode plate before anodization having the positive electrode current collector 1 of FIG. 1 was produced. Each step was performed by a normal method.
The negative electrode plate has a negative electrode current collector having the same shape as the positive electrode current collector 1 shown in FIG. 0 mm, the dimension S4=45.0 mm, and the thickness (cross-sectional area perpendicular to the longitudinal direction) of the central rib 112 is 0.75 mm. The production of the negative electrode plate before anodization was also carried out by carrying out the same steps as those of the positive electrode plate in the usual manner.

Next, seven sheets of the obtained negative electrode plates before chemical conversion were placed in a bag-like separator made of polyethylene, and six sheets of the obtained positive electrode plates before chemical conversion were alternately laminated to obtain a laminate. Next, using a COS (cast-on-strap) casting apparatus, straps, intermediate poles, and terminal poles were formed on the positive electrode plate and the negative electrode plate of each laminate to obtain an electrode plate assembly.
Six of these electrode plate groups are prepared and placed in each cell chamber of the container, resistance welding of the intermediate pole column between adjacent cell chambers, heat welding of the container and lid, and insertion from the injection hole into each cell chamber. A D23-type flooded lead-acid battery for idling stop was assembled by performing normal steps such as injecting the electrolyte and closing the injection hole.
After that, the specific gravity after forming the container was set to 1.285 (converted value at 20° C.) by forming the container by a normal method. Thus, No. 1 lead-acid battery was obtained.
The lead-acid battery thus obtained was disassembled, and the ratio a/b of the mass a of the positive electrode current collector segment having the positive electrode current collector lugs to the mass b of the positive electrode current collector segment not having the lugs was determined. was calculated, and a result of 1.5 was obtained.

<Sample No.2>
The lead-acid battery of sample No. 2 has the positive electrode current collector 1 having the shape shown in FIG. is the same as sample No.1. Except for using the positive electrode current collector 1 of sample No. 2, in the same manner as sample No. 1, after assembling a D23 type liquid lead-acid battery for idling stop, the container was formed, and the lead of No. 2 was used. Got a battery.
<Sample No.3>
The lead-acid battery of sample No. 3 has the positive electrode current collector 1 having the shape shown in FIG. is the same as sample No.1. Except for using the positive electrode current collector 1 of sample No. 3, in the same manner as sample No. 1, after assembling a D23 type liquid lead-acid battery for idling stop, the container was formed, and the lead of No. 3 was used. Got a battery.
<Sample No.4>
The lead-acid battery of sample No. 4 has the positive electrode current collector 1 having the shape shown in FIG. is the same as sample No.1. Except for using the positive electrode current collector 1 of sample No. 4, in the same manner as sample No. 1, after assembling a D23 type liquid lead-acid battery for idling stop, the container was formed, and the lead of No. 4 was used. Got a battery.

<Sample No.5>
The lead-acid battery of sample No. 5 has the positive electrode current collector 1 having the shape shown in FIG. is the same as sample No.1. Except for using the positive electrode current collector 1 of sample No. 5, in the same manner as sample No. 1, after assembling a D23 type liquid lead-acid battery for idling stop, the container was formed, and the lead of No. 5 was used. Got a battery.
<Sample No.6>
The lead-acid battery of sample No. 6 has the positive electrode current collector 1 having the shape shown in FIG. is the same as sample No.1. Except for using the positive electrode current collector 1 of sample No. 6, in the same manner as sample No. 1, after assembling a D23 type liquid lead-acid battery for idling stop, the container was formed, and the lead of No. 6 was used. Got a battery.

<Sample No.7>
The lead-acid battery of sample No. 7 has a positive electrode current collector 1A having the shape shown in FIG. 0 mm, the thickness of the central rib 112a (cross-sectional area perpendicular to the longitudinal direction) is 0.80 mm, and the thickness of the central rib 112b is 1.20 mm. Except for using the positive electrode current collector 1A of sample No. 7, the same method as sample No. 1 was used to assemble a D23 type idling stop flooded lead-acid battery and then perform container formation. Got a battery.

[Each resistance value measurement of the cut surface of the divided body]
First, the obtained lead-acid batteries of samples No. 1 to No. 7 were disassembled, the positive electrode plate was taken out, and the positive electrode active material was removed from the positive electrode plate and washed to obtain each of No. 1 to No. 7. Positive electrode current collectors 1 and 1A were obtained. Next, the positive electrode current collectors 1 and 1A are cut with scissors along the diagonal lines T shown in FIGS. Obtained. In the divided body 2 where the ears are present, the first portion 21 divided by the reference line K has 13 cut surfaces of the central bone 112 . In the divided body 2A where the ears are present, the first portion 21A divided by the reference line K has a total of 13 cut surfaces of the middle ribs 112a and 112b.

Next, each resistance value Rn (R1 to R13) between the center point P of the ear 12 and the cut planes C1 to C13 of each middle bone was measured three times each using a resistance meter (3554 BATTERY HiTESTER manufactured by Hioki). It was measured and the average value was calculated. Further, distances Xn (X1 to X13) between the center point P and the center points of the cut surfaces C1 to C13 were measured with a ruler. Tables 1 to 7 show the results of these measurements (each resistance value Rn is the average value of three measurements).

[Method for calculating the mass ratio a/b of the divided bodies]
After measuring the resistance values of the cut surfaces of the divided body, the ear 12 of the divided body 2 or 2A where the ear exists is cut along the boundary line L between the upper bone 111 of the ear 12 and the upper bone 111 . The mass of the divided body 2 or 2A remaining after the ear 12 was cut was a, and the mass was measured three times using a mass meter, and the average value was calculated. In addition, the mass b was similarly measured for the divided body without ears, and the average value was calculated. Using the average value of mass a and the average value of mass b, the ratio a/b of the divided bodies was calculated.

Next, for each sample, the measurement results were plotted on a coordinate plane in which both the x-axis and the y-axis are linear scales, with the resistance value Rn (average value of three measurements) as the y-coordinate and the distance Xn as the x-coordinate. As a result, the graphs shown in FIGS. 5 to 11 were obtained. Fig. 5 shows the results of No. 1, Fig. 6 shows the results of No. 2, Fig. 7 shows the results of No. 3, Fig. 8 shows the results of No. 4, Fig. 9 shows the results of No. 5, FIG. 10 shows the results of No. 6, and FIG. 11 shows the results of No. 7, respectively.
As shown in FIG. 5, in sample No. 1, all plots could be approximated to two straight lines T1 and T2 with different slopes with x=H (a value between X8 and X9) as the intersection point. Next, the average value A of each resistance value (average value of three measurements) R1 to R8 at each distance X1 to X8 where x<H, and each resistance value at each distance X9 to X13 where x≧H (Average value of three measurements) The average value B of Rn was calculated, and the ratio A/B was calculated from these calculated values. Table 8 shows the results.

As shown in Table 8, the ratio A/B of sample No. 1 was 0.31.
In addition, as shown in FIGS. 6 to 10, in samples No. 2 to No. 6, all plots are two plots with different slopes with x = H (a value between X9 and X10) as the intersection point. It could be approximated to straight lines T1 and T2. Next, the average value A of each resistance value (average value of three measurements) R1 to R9 at each distance X1 to X9 where x<H, and each resistance value at each distance X10 to X13 where x≧H (Average value of three measurements) The average value B of Rn was calculated, and the ratio A/B was calculated from these calculated values. The results are shown in Tables 9 to 13.

As shown in Tables 9 to 13, the ratio A/B of sample No. 2 is 0.35, the ratio A/B of sample No. 3 is 0.45, and the ratio A/B of sample No. 4 is 0.35. 50, the ratio A/B of sample No. 5 was 0.55, and the ratio A/B of sample No. 6 was 0.65.
Furthermore, as shown in FIG. 11, in sample No. 7, all plots could be approximated to two straight lines T1 and T2 with different slopes with x=H (the value of X10) as the intersection point. Next, the average value A of each resistance value (average value of three measurements) R1 to R9 at each distance X1 to X9 where x<H, and each resistance value at each distance X10 to X13 where x≧H (Average value of three measurements) The average value B of Rn was calculated, and the ratio A/B was calculated from these calculated values. The results are shown in Table 14.

As shown in Table 14, the ratio A/B of sample No. 7 was 0.55.
[Test and Evaluation]
The obtained No.1 to No.7 lead-acid batteries were subjected to a life test using an EUCAR power assist profile. FIG. 12 shows the charge/discharge pattern of one cycle of this test. C2 is the ₂ hour rate capacity. In this charge/discharge pattern, there is deep discharge in the partially charged state.
After 100 cycles of this life test, the specific gravity of the electrolyte was measured at the upper and lower portions of the battery case using an optical hydrometer, and the difference in specific gravity between the upper and lower portions was calculated from these measured values.
These results are shown in Table 15 together with the structure of the grid-like substrate of each sample.

As can be seen from Table 15, in No. 1 and No. 6 lead-acid batteries that do not satisfy 0.35 ≤ A/B ≤ 0.55, the difference in the upper and lower specific gravities of the electrolyte was 0.070 and 0.040. On the other hand, in No. 2 to No. 5 and No. 7 lead-acid batteries that satisfy 0.35 ≤ A / B ≤ 0.55, the difference in the upper and lower specific gravities of the electrolyte was as small as 0.005 to 0.015. . In addition, the life of No. 1 and No. 6 lead-acid batteries not satisfying 0.35 ≤ A / B ≤ 0.55 was 8000 to 8500 cycles, whereas 0.35 ≤ A / B ≤ 0 No. 2 to No. 5 and No. 6 lead-acid batteries satisfying .55 had a long life of 17,000 to 22,000 cycles.

From the above results, the mass a of the divided body having positive electrode current collector satisfying 0.35≦A/B≦0.55 and having positive electrode current collector tabs and the division without positive electrode current collector ears It was confirmed that the flooded lead-acid battery whose ratio a/b to the mass b of the body is 1.5 suppresses the stratification of the electrolyte solution when used in a partially charged state, and can extend the life of the battery. Note that when the ratio a/b of the mass a of the positive electrode current collector segment where the positive electrode current collector ears are present and the mass b of the positive electrode current collector segment where the positive electrode current collector ears are not present is 1.1 or more and 1.9 or less, The potential distribution of the positive electrode current collector is improved, and stratification of the electrolytic solution is further suppressed, so that the service life can be lengthened.

1 positive electrode current collector 1A positive electrode current collector 11 grid substrate 11A grid substrate 12 ear 111 upper bone 112 middle bone 112a middle bone 112b middle bone 2 divided body with ears 2A divided body with ears 21 first Part 21A First part 22 Second part 22A Second part

Claims (1)

A liquid lead-acid battery comprising a positive electrode plate having a positive electrode current collector and a positive electrode mixture,
The positive electrode current collector has a rectangular grid-like substrate and ears continuous with the grid-like substrate,
The positive electrode mixture is held on the grid-like substrate,
The lattice-like substrate has an upper rib along one side of the rectangle and a plurality of middle ribs connected to the upper bone and existing below the upper bone,
the ear protrudes upward from a position shifted to one side from the center of the one side of the upper bone;
Of the divided bodies produced by cutting the positive electrode current collector along a diagonal line passing through the one corner of the rectangle, the divided body in which the ear exists is the center on the boundary line between the ear and the upper bone. A reference line passing through a point P and perpendicular to the upper bone is divided into a first portion and a second portion, the first portion having a larger area than the second portion;
Each resistance value Rn between each cutting plane Cn of the plurality of midribs and the center point P in the first portion is represented by the y-coordinate on a coordinate plane in which both the x-axis and the y-axis are linear scales, All the plots made with each distance Xn between the center point of each cut surface Cn and the center point P as the x coordinate can be approximated to two straight lines with different slopes with x = H as the intersection point,
The ratio A/B between the average value A of each resistance value Rn at each distance Xn satisfying x<H and the average value B of each resistance value Rn at each distance Xn satisfying x≧H is 0.35. 0.55 or less,
The ratio of the mass a of the portion of the segmented body in which the positive electrode current collector ear exists and the segment left after the segment is cut along the boundary line to the mass b of the segmented body in which the positive electrode current collector ear does not exist A flooded lead-acid battery, wherein a/b is 1.1 or more and 1.9 or less.

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