JP2021111626A - Liquid type lead storage battery - Google Patents

Abstract

To provide a novel liquid type lead storage battery, in which stratification of electrolyte is restrained by an agitation action due to gas generated during charging even when the battery is used under a partial charging state.SOLUTION: A split body 2 generated by cutting a positive electrode collector 1 along a diagonal line D passing through a corner on one side of a rectangle forming a lattice-like substrate 11 and having an ear is divided into a first portion 21 and a second portion 22 by a reference line K. On a coordinate plane having an x-axis and a y-axis as linear scales, all plots have each resistance value between each cutting face and a center point P at the first portion 21 as a y-coordinate and each distance between the center point of each cutting face and the center point P as an x-coordinate. A ratio A/B of an average value A of each resistance value at each distance approximating to two straight lines with different inclination with x=H as a crossing point and satisfying x<H and an average value B of each resistance value at each distance satisfying x≥H is 0.35 or more and 0.55 or less, and porosity of a positive electrode active material of a positive electrode mixture is 35% or more and 55% or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a liquid lead-acid battery.

With the seriousness of environmental problems in recent years, emission regulations for automobiles and the like have become stricter worldwide. To comply with this regulation, automobile manufacturers have developed various environmental technologies. As the environmental technology, an idling stop system (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, so that fuel efficiency can be improved and the amount of exhaust gas can be reduced.

Liquid lead-acid batteries for ISS vehicles are charged and discharged in a partially charged state (also referred to as Partial State of Charge, also referred to as "PSOC"), which is not a fully charged state because the engine frequently stops and starts. Is repeated. Liquid lead-acid batteries for ISS vehicles are used in a partially charged state with a charge rate of 80% to 90% because if the charge rate is higher than 90%, the charge acceptability is low and the utilization efficiency of regenerative energy is reduced. It is desirable to be done.

Stratification of the electrolytic solution, which is one of the deterioration factors of the liquid lead-acid battery, is a phenomenon in which the concentration difference of the electrolytic solution occurs between the upper part and the lower part in the battery case, and the partially charged state of 80% to 90% is maintained. It tends to occur when using a liquid lead-acid battery by controlling it so as to do so. In the upper part where the concentration of the electrolytic solution is low, dendritic crystals (dendrites) of metal lead are deposited and grown on the surface of the negative electrode plate, and an internal short circuit is likely to occur. On the other hand, in the lower part where the concentration of the electrolytic solution is high, the high concentration of the electrolytic solution tends to cause sulfation in which the non-conductor lead sulfate is enlarged on the surface of the negative electrode plate.

When sulfation occurs, the release of sulfuric acid from the negative electrode active material is suppressed, so that the charge acceptability of the lower part of the negative electrode plate is lowered. When the charge acceptability of the lower part of the negative electrode plate is lowered, the charge / discharge reaction mainly proceeds in the upper part of the negative electrode plate. Corrosion of the substrate made of lead alloy progresses, and the liquid lead-acid battery reaches the end of its life at an early stage.

As a technique for suppressing the stratification of the electrolytic solution, for example, the technique described in Patent Document 1 can be mentioned.
In Patent Document 1, in order to more effectively utilize the stirring action of the electrolytic solution by the gas generated during charging and suppress stratification, the upper part of the accommodating space and the accommodating space accommodating the electrode plates are separately provided. It is described that a communication flow path that communicates with the lower part is provided. As a result, during charging, an upward flow of the electrolytic solution due to the rise of the gas generated by the electrode plates is generated in the accommodation space, and a corresponding downward flow is generated in the convection flow path. Therefore, it is described that the effective convection of the electrolytic solution in the electric tank enhances the stirring action of the electrolytic solution and suppresses stratification.

On the other hand, the liquid lead-acid battery includes a positive electrode plate in which the positive electrode mixture is held in the positive electrode current collector and a negative electrode plate in which the negative electrode mixture is held in the negative electrode current collector. The positive electrode current collector and the negative electrode current collector have, for example, a rectangular grid-like substrate and a continuous ear on the grid-like substrate, as shown in FIG. 1 of Patent Document 2. The grid-like substrate has an upper bone along one side of a rectangle forming the grid-like substrate, and a plurality of middle bones connected to the upper bone and located below the upper bone. The ear protrudes upward from a position offset from the center of one side of the upper bone to one side.
However, Patent Documents 1 and 2 do not describe the relationship between the potential distribution of the electrode plate during charging and discharging and the stirring action of the electrolytic solution.

Japanese Unexamined Patent Publication No. 2015-176659 Japanese Patent No. 3452171

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

In order to solve the above problems, it is a gist that 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 provided with a positive electrode current collector and a positive electrode plate having a positive electrode mixture. The positive electrode current collector has a rectangular grid-like substrate and continuous ears on the grid-like substrate, and the positive electrode mixture is held on the grid-like substrate. The grid-like substrate has an upper bone along one side of a rectangle forming the grid-like substrate, and a plurality of middle bones connected to the upper bone and located below the upper bone. The ear protrudes upward from a position offset from the center of one side of the upper bone to one side.

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

(3) On a coordinate plane in which both the x-axis and the y-axis are linear scales, the y-coordinates are the resistance values Rn between each cut surface Cn of the plurality of central bones and the center point P in the first part. All 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 having different slopes with x = H as the intersection, and x <H. The ratio A / B by 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 where x ≧ H is 0.35 or more and 0.55 or less. be.
The above-mentioned "approximate to a straight line" means that the absolute value | ρ | of the correlation coefficient ρ when a plurality of plots are linearly regressed by the least squares method is 0.90 or more. Further, "two straight lines having 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) The porosity of the positive electrode active material of the positive electrode mixture is 35% or more and 55% or less. It should be noted that this value is a value measured by analyzing a positive electrode mixture separated from a completely dried positive electrode plate of a liquid lead-acid battery in a state where the charge rate is 100%.

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

It is a front view which shows the positive electrode current collector which constitutes the positive electrode plate which the liquid-type lead-acid battery of 1st Embodiment has. FIG. 5 is a front view showing a split body having ears formed by cutting a positive electrode current collector of FIG. 1 along a diagonal line passing through a corner on one side of a rectangle forming a grid-like substrate. It is a front view which shows the positive electrode current collector which constitutes the positive electrode plate which the liquid-type lead-acid battery of the 2nd Embodiment has. FIG. 3 is a front view showing a split body having ears formed by cutting a positive electrode current collector of FIG. 3 along a diagonal line passing through a corner on one side of a rectangle forming a grid-like substrate. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for the sample No. 1 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for the sample No. 2 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for sample No. 3 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for sample No. 4 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for sample No. 5 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for sample No. 6 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. The resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P of the ear in the first part of the positive electrode current collector obtained for sample No. 7 prepared in the example. , Is a graph showing the relationship between each distance Xn between the center point of each cut surface Cn and the center point P of the ear. It is a graph which shows the charge / discharge pattern of one cycle of the life test performed in an Example.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are made for carrying out the present invention, but these limitations are not essential requirements of the present invention.

[Structure of liquid lead-acid batteries of the first embodiment and the second embodiment]
The liquid lead-acid batteries of the first embodiment and the second embodiment include a monoblock type battery case, a lid, and a group of six plates. The battery case is divided into six cell chambers by a partition wall. The six cell chambers are arranged along the longitudinal direction of the battery case. One electrode plate group is arranged in each cell chamber. An electrolytic solution is injected into each cell chamber.
Each electrode plate group has a laminate composed of a plurality of alternately arranged positive electrode plates and negative electrode plates, and separators arranged 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 that are continuous with the grid-like substrate, and the positive electrode mixture is held on the grid-like substrate. Further, the porosity of the positive electrode active material of the positive electrode mixture is 35% or more and 55% or less. This value is a value measured by analyzing a positive electrode mixture separated from a completely dried positive electrode plate of a liquid lead-acid battery in a state where the charge rate is 100%.

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 that are continuous with the grid-like substrate, and the negative electrode mixture is held on the grid-like substrate. A plurality of positive electrode plates and negative electrode plates are alternately arranged via a separator. _{The number M n} of the negative electrode plates constituting the laminated body is one more than the number M _{p of the positive electrode plates.} The number of negative electrode plates Mn may be one less than the number of positive electrode plates Mp, or may be the same.

The negative electrode plate is housed in a bag-shaped separator. Then, by alternately stacking the bag-shaped separator containing the negative electrode plate and the positive electrode plate, the separator is arranged between the positive electrode plate and the negative electrode plate. The positive electrode plate may be stored in the bag-shaped separator and alternately stacked with the negative electrode plate.

Further, each electrode plate group includes a positive electrode strap and a negative electrode strap that connect a plurality of positive electrode plates and a negative electrode plate constituting the laminate at different positions in the width direction, and a positive electrode intermediate pole column that rises from the positive electrode strap and the negative electrode strap, respectively. It also has a negative electrode intermediate pole pillar, and a positive electrode pole pillar and a negative electrode pole pillar serving as external terminals.

The positive electrode strap and the negative electrode strap connect and fix the ears of the plurality of positive electrode plates and the negative electrode plates, respectively. The positive electrode intermediate pole columns and the negative electrode intermediate pole columns of the adjacent cell chambers are resistance welded to each other, and the adjacent cells are electrically connected in series.
The positive electrode pole and the negative electrode pole pillar are formed on the positive electrode strap and the negative electrode strap arranged in the cell chambers at both ends in the cell arrangement direction via small pieces.

[Positive 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 positive electrode mixture is held on the grid-like substrate 11. Has been done. The grid-like substrate 11 has an upper bone 111 along one side of a rectangle forming the grid-like substrate 11, and a plurality of middle bones 112 connected to the upper bone 111 and located below the upper bone 111. The ear 12 projects upward from a position deviated from the center of one side of the upper bone 111 to one side (right side in FIG. 1).

Of the divided bodies formed by cutting the positive electrode current collector 1 along the diagonal line D passing through the right (one side) corner of the rectangle forming the grid-like substrate 11, the divided bodies having ears are shown in FIG. show. The split body 2 is divided into a first portion 21 and a second portion 22 by a reference line K that passes through the center point P on the boundary line L of the ear 12 with the upper bone 111 and is perpendicular to the upper bone 111. The first portion 21 has a larger area than the second portion 22.

The first portion 21 has a cut surface of 13 middle bones 112. On a coordinate plane in which both the x-axis and the y-axis are linear scales, the resistance values R1 to R13 between each of the 13 cut surfaces C1 to C13 and the center point P are set to the y coordinate, and the center of each cut surface C1 to C13. When each distance X1 to X13 between the point and the center point P is plotted as the x coordinate, all the plots can be approximated to two straight lines having different slopes with x = H as the intersection. The ratio A / B by the average value A of each resistance value Rn at each distance Xn where x <H and the average value B of each resistance value Rn at each distance Xn where x ≧ H is 0.35. It is 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 of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction) is as a whole. It is the same, which is to 0.85mm ² more than 1.00mm ² below.
The positive electrode current collector 1 can be obtained by a usual method such as a punching method, an expanding method, or a gravity casting method.

[Positive current collector of the second embodiment]
As shown in FIG. 3, the positive electrode current collector 1A of the second embodiment has a rectangular grid-like substrate 11A and ears 12 continuous with the grid-like substrate 11A, and the positive electrode mixture is held by the grid-like substrate 11A. Has been done. The grid-like substrate 11A has an upper bone 111 along one side of a rectangle forming the grid-like substrate 11A, and a plurality of middle bones connected to the upper bone 111 and located below the upper bone 111. The thickness of the middle bone changes at the intermediate position in the vertical direction, and the middle bone 112a above the intermediate position (upper bone 111 side) is thinner than the thickness of the middle bone 112b below the intermediate position.
The ear 12 projects upward from a position deviated from the center of one side of the upper bone 111 to one side (right side in FIG. 3).

Of the divided bodies formed by cutting the positive electrode current collector 1A along the diagonal line D passing through the right (one side) corner of the rectangle forming the grid-like substrate 11A, the divided bodies having ears are shown in FIG. show. The split body 2A is divided into a first portion 21A and a second portion 22A by a reference line K that passes through the center point P on the boundary line L of the ear 12 with the upper bone 111 and is perpendicular to the upper bone 111. The first portion 21A has a larger area than the second portion 22A.

The first portion 21A has 13 cut surfaces of the middle bone. The cut surfaces C1 to C5 are the cut surfaces of the middle bone 112a, and the cut surfaces C6 to C13 are the cut surfaces of the middle bone 112b. On a coordinate plane in which both the x-axis and the y-axis are linear scales, the resistance values R1 to R13 between each of the 13 cut surfaces C1 to C13 and the center point P are set to the y coordinate, and the center of each cut surface C1 to C13. When each distance X1 to X13 between the point and the center point P is plotted as the x coordinate, all the plots can be approximated to two straight lines having different slopes with x = H as the intersection. The ratio A / B by the average value A of each resistance value Rn at each distance Xn where x <H and the average value B of each resistance value Rn at each distance Xn where x ≧ H is 0.35. It is 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 of the middle bone 112a (cross-sectional area perpendicular to the longitudinal direction) is 0. 75 mm ² or more and 0.85 mm ² or less, and the thickness of the middle bone 112b (cross-sectional area perpendicular to the longitudinal direction) is 1.15 mm ² or more and 1.25 mm ² or less.
The positive electrode current collector 1A can be obtained by a usual method such as a punching method, an expanding method, or a gravity casting method.

[Porosity of positive electrode active material]
As described above, in the liquid lead-acid batteries of the first embodiment and the second embodiment, the porosity of the positive electrode active material of the positive electrode mixture is 35% or more and 55% or less. It should be noted that this value is a value measured by analyzing a positive electrode mixture separated from a completely dried positive electrode plate of a liquid lead-acid battery in a state where the charge rate is 100%.
The porosity of the positive electrode active material can be adjusted by, for example, the following method.
The porosity of the positive electrode active material can be adjusted by the temperature at the time of chemical conversion, and the higher the chemical conversion temperature, the smaller the porosity. Adjust as appropriate so that it is less than%.
Further, the porosity of the positive electrode active material of the positive electrode mixture can be measured by, for example, a mercury press-fitting method.

[Action, effect]
The smaller the ratio A / B of the positive electrode current collector of the liquid lead-acid battery, the easier it is for the lower part of the positive electrode plate to polarize than the upper part during charging. Even so, the stirring action of the electrolytic solution can be obtained. However, when the ratio A / B is less than 0.35, the resistance value of the path from the lower part of the positive electrode current collector to the ear is significantly larger than the resistance value of the path from the upper part to the ear. The charge / discharge reaction becomes difficult to proceed. Therefore, the amount of gas generated from the lower part is insufficient to obtain the electrolytic solution stirring action in the partially charged state.
In a liquid lead-acid battery in which the ratio A / B of the positive electrode current collector is larger than 0.55, the charge / discharge reaction does not easily proceed in the entire positive electrode plate. It will be insufficient to obtain.

When 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, the first embodiment and the second embodiment In the liquid lead-acid battery of the form, since the charge / discharge reaction is uniformly performed in the entire positive electrode plate, the amount of gas generated from the lower part is sufficient to obtain the stirring action of the electrolytic solution in the partially charged state. .. Therefore, according to the liquid lead-acid batteries of the first embodiment and the second embodiment, the stratification of the electrolytic solution is suppressed when the lead-acid battery is used in a partially charged state, and the life can be extended.

Further, the liquid lead-acid batteries of the first embodiment and the second embodiment are electrolyzed when the porosity of the positive electrode active material of the positive electrode mixture is 35% or more and 55% or less in a state where the charge rate is 100%. It is possible to further enhance the effect of suppressing the stratification of the liquid and obtain a higher effect of improving the life.
In a liquid lead-acid battery, water in the electrolytic solution is electrolyzed during charging to generate gas. Compared with a liquid lead-acid battery in which the porosity of the positive electrode active material is 30% even if the positive electrode current collector satisfies 0.35 ≦ A / B ≦ 0.55, it is 35% or more and 55% or less. As a result, the contact area between the positive electrode active material and the electrolytic solution is reduced, and the amount of gas generated on the positive electrode plate in the partially charged state is reduced, so that the effect of suppressing stratification of the electrolytic solution is reduced.
Further, in the case of a liquid lead-acid battery in which the positive electrode current collector satisfies 0.35 ≦ A / B ≦ 0.55 and the porosity of the positive electrode active material is 60%, it is compared with that of 35% or more and 55% or less. As a result, the positive electrode active material tends to soften, which may lead to the positive electrode active material falling off and the life performance may be deteriorated.

[Aspect of method]
As a second aspect of the present invention, there is a method of designing a positive electrode current collector constituting a positive electrode plate of a liquid lead-acid battery. This design method has the following configurations (a) to (c).
(a) The positive current collector has a rectangular grid-like substrate and continuous ears on the grid-like substrate, and the positive electrode mixture is held on the grid-like substrate, and the grid-like substrate has an upper bone along one side of the rectangle. And a plurality of middle bones connected to the upper bone and existing below the upper bone, and the ear protrudes upward from a position deviated from the center of one side of the upper bone to one side.
(b) Of the divisions formed by cutting the positive current collector along the diagonal line passing through the corner on one side of the rectangle, the divisions in which the ears are present are defined by the center point P on the boundary line with the upper bone of the ears. It is divided into the first part and the second part by the reference line perpendicular to the upper bone of the street.
(c) On a coordinate plane in which both the x-axis and the y-axis are linear scales, between each cut surface Cn of a plurality of middle bones and the center point P in the first portion having a larger area than the second portion. All plots made with each resistance value Rn of the above as the y coordinate and each distance Xn between the center point and the center point P of each cut plane Cn as the x coordinate are two straight lines having different slopes with x = H as the intersection. The ratio A / B is calculated by the average value A of each resistance value Rn at each distance Xn where x <H and the average value B of each resistance value Rn at each distance Xn where x ≧ H. It should be 0.35 or more and 0.55 or less.

[Preparation of test battery]
Sample No. 1 to No. 35 liquid lead-acid batteries were produced as liquid lead-acid batteries having the same structure as the liquid lead-acid batteries of the embodiment.
The liquid lead-acid batteries of Samples No. 1 to No. 35 are D23 type liquid lead-acid batteries for ISS vehicles.
Samples No. 1 to No. 7 differ in the shape of the grid-like substrate of the positive electrode current collector, but all other points have the same configuration.
Samples No. 8 to No. 11 have the same shape as the sample No. 1 in the shape of the grid-like substrate of the positive electrode current collector. Samples No. 1 and No. 8 to No. 11 have different porosities of the positive electrode active material, but all other points have the same configuration.
Samples No. 12 to No. 15 have the same shape of the grid-like substrate of the positive electrode current collector as that of sample No. 2. Samples No. 2 and Nos. 12 to 15 differ in the porosity of the positive electrode active material, but all other points have the same configuration.
Samples No. 16 to No. 19 have the same shape of the grid-like substrate of the positive electrode current collector as Sample No. 3. Samples No. 3 and Nos. 16 to 19 differ in the porosity of the positive electrode active material, but all other points have the same configuration.
Samples No. 20 to No. 23 have the same shape of the grid-like substrate of the positive electrode current collector as Sample No. 4. Samples No. 4 and No. 20 to No. 23 have different porosities of the positive electrode active material, but all other points have the same configuration.
Samples No. 24 to No. 27 have the same shape of the grid-like substrate of the positive electrode current collector as that of sample No. 5. Samples No. 5 and No. 24 to No. 27 have different porosities of the positive electrode active material, but all other points have the same configuration.
Samples No. 28 to No. 31 have the same shape of the grid-like substrate of the positive electrode current collector as sample No. 6. Samples No. 6 and No. 28 to No. 31 have different porosities of the positive electrode active material, but all other points have the same configuration.
Samples No. 32 to No. 35 have the same shape of the grid-like substrate of the positive electrode current collector as Sample No. 7. Samples No. 7 and No. 32 to No. 35 have different porosities of the positive electrode active material, but all other points have the same configuration.

<Sample No.1 and No.8 to No.11>
The liquid lead-acid batteries of Samples No. 1 and No. 8 to No. 11 have a positive electrode current collector 1 having the shape shown in FIG. 1, and have dimensions S1 = 115.0 mm, dimensions S2 = 110.0 mm, and dimensions S3. = 100.0 mm, dimension S4 = 45.0 mm, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction) is 1.05 mm ² .
First, a punching process for a strip-shaped lead alloy sheet (size corresponding to a plurality of positive electrode current collectors 1), a step of filling a lattice-shaped substrate 11 with a positive electrode active material paste, a preheating drying step, an aging drying step, and By performing the cutting step, a positive electrode plate before chemical formation having the positive electrode current collector 1 of FIG. 1 was produced. Each step was carried out by a usual 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. 1, but the negative electrode current collector has dimensions S1 = 114.0 mm, dimensions S2 = 108.0 mm, and dimensions S3 = 100. It is 0 mm, the dimension S4 = 45.0 mm, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction) is 0.75 mm ² . The negative electrode plate before chemical conversion was also produced by performing each step in the same manner as the positive electrode plate by a usual method.
Next, seven sheets of the obtained pre-chemical negative electrode plates placed in a polyethylene bag-shaped separator and six pre-chemical positive electrode plates obtained were alternately laminated to obtain a laminate. Next, a group of electrode plates was obtained by forming straps, intermediate electrode columns, and terminal electrode columns on the positive electrode plate and the negative electrode plate of each laminate using a COS (cast-on-strap) type casting apparatus.

Six groups of these plates are prepared and placed in each cell chamber of the battery chamber, and resistance welding of intermediate pole columns between adjacent cell chambers, heat welding of the battery tank and lid, and liquid injection holes into each cell chamber. A liquid lead-acid battery for a D23 type ISS vehicle was assembled by performing normal steps such as injecting an electrolytic solution and closing the injection hole.
Then, by carrying out the electric tank chemical conversion by a usual method, the specific density after the electric tank chemical conversion was set to 1.285 (20 ° C. conversion value). The chemical conversion conditions were set so that the charge rate of the liquid lead-acid battery after chemical conversion of the battery case would be 100%.
In addition, by adjusting the temperature at the time of chemical conversion during the chemical conversion of the battery case, the porosity of the positive electrode active material is 40% for sample No. 1, 30% for No. 8, 35% for No. 9, and No. It was set to 55% at .10 and 60% at No.11.
In this way, sample No. 1 and samples No. 8 to No. 11 liquid lead-acid batteries were obtained.

<Samples No. 2 and No. 12 to No. 15>
The liquid lead-acid batteries of Samples No. 2 and No. 12 to No. 15 have a positive electrode current collector 1 having the shape shown in FIG. 1 and have a thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). It is 1.00 mm ^2. Other than that, sample No. 2 is the same as sample No. 1, sample No. 12 is the same as sample No. 8, sample No. 13 is the same as sample No. 9, and sample. No. 14 is the same as sample No. 10, and sample No. 15 is the same as sample No. 11.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as samples No. 1 and No. 8 to No. 11, except that the thickness of the central bone 112 of the positive electrode current collector used is different. Tank chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 2 and No. 12 to No. 15.

<Samples No.3 and No.16 to No.19>
The liquid lead-acid batteries of Samples No. 3 and No. 16 to No. 19 have a positive electrode current collector 1 having the shape shown in FIG. 1 and have a thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). It is 0.95 mm ^2. Other than that, sample No. 3 is the same as sample No. 1, sample No. 16 is the same as sample No. 8, sample No. 17 is the same as sample No. 9, and sample. No. 18 is the same as sample No. 10, and sample No. 19 is the same as sample No. 11.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as samples No. 1 and No. 8 to No. 11, except that the thickness of the central bone 112 of the positive electrode current collector used is different. Tank chemicals were carried out to obtain liquid lead-acid batteries of Samples No. 3 and No. 16 to No. 19.

<Samples No.4 and No.20 to No.23>
The liquid lead-acid batteries of Samples No. 4 and No. 20 to No. 23 have a positive electrode current collector 1 having the shape shown in FIG. 1 and have a thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). It is 0.90 mm ^2. Other than that, sample No. 4 is the same as sample No. 1, sample No. 20 is the same as sample No. 8, sample No. 21 is the same as sample No. 9, and sample. No.22 is the same as sample No.10, and sample No.23 is the same as sample No.11.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as samples No. 1 and No. 8 to No. 11, except that the thickness of the central bone 112 of the positive electrode current collector used is different. Tank chemicals were carried out to obtain liquid lead-acid batteries of Samples No. 4 and No. 20 to No. 23.

<Sample No.5 and No.24 to No.27>
The liquid lead-acid batteries of Samples No. 5 and No. 24 to No. 27 have a positive electrode current collector 1 having the shape shown in FIG. 1 and have a thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). It is 0.85 mm ^2. Other than that, sample No. 5 is the same as sample No. 1, sample No. 24 is the same as sample No. 8, sample No. 25 is the same as sample No. 9, and sample. No. 26 is the same as sample No. 10, and sample No. 27 is the same as sample No. 11.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as samples No. 1 and No. 8 to No. 11, except that the thickness of the central bone 112 of the positive electrode current collector used is different. Tank chemicals were carried out to obtain liquid lead-acid batteries of Samples No. 5 and No. 24 to No. 27.

<Sample No.6 and No.28-No.31>
The liquid lead-acid batteries of Samples No. 6 and No. 28 to No. 31 have a positive electrode current collector 1 having the shape shown in FIG. 1 and have a thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). It is 0.75 mm ^2. Other than that, sample No. 6 is the same as sample No. 1, sample No. 28 is the same as sample No. 8, sample No. 29 is the same as sample No. 9, and sample. No. 30 is the same as sample No. 10, and sample No. 31 is the same as sample No. 11.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as samples No. 1 and No. 8 to No. 11, except that the thickness of the central bone 112 of the positive electrode current collector used is different. Tank chemicals were carried out to obtain liquid lead-acid batteries of Samples No. 6 and No. 28 to No. 31.

<Samples No.7 and No.32 to No.35>
The liquid lead-acid batteries of Samples No. 7 and No. 32 to No. 35 have a positive electrode current collector 1A having the shape shown in FIG. 3, and have dimensions S1 = 115.0 mm, dimensions S2 = 110.0 mm, and dimensions S3. = 100.0 mm, dimension S4 = 45.0 mm, thickness of middle bone 112a (cross-sectional area perpendicular to longitudinal direction) 0.80 mm ² , thickness of middle bone 112b (cross-sectional area perpendicular to longitudinal direction) 1 .20 mm ² .
Other than that, sample No. 7 is the same as sample No. 1, sample No. 32 is the same as sample No. 8, sample No. 33 is the same as sample No. 9, and sample. No.34 is the same as sample No.10, and sample No.35 is the same as sample No.11.
After assembling the liquid lead-acid battery for D23 type ISS vehicle by the same method as samples No. 1 and No. 8 to No. 11 except that the positive electrode current collector 1A in FIG. 3 was used, the battery case was formed. , Samples No. 7 and No. 32 to No. 35 liquid lead-acid batteries were obtained.

[Measurement of porosity of positive electrode active material]
The obtained liquid lead-acid batteries of Samples No. 1 to No. 35 were disassembled, a positive electrode plate randomly selected for each sample was taken out, and the porosity of the positive electrode active material of the positive electrode mixture was examined by the following method. ..
First, the positive electrode plate was dried (completely dried) at 60 ° C. for 4 hours or more in an incubator, then the positive electrode mixture was separated from the positive electrode substrate and ground in an agate mortar to form a powder. Next, this powder was sieved, and the powder that passed through the sieve was used as a positive electrode mixture sample. Next, the obtained positive electrode mixture sample was passed through a mercury porosimeter (AutoPore IV 9500, Shimadzu Corporation) to measure the porosity of the positive electrode active material for each sample. The press-fitting pressure was from 0.0138 MPa to 413.685 MPa.

[Measurement of each resistance value of the cut surface of the split body]
Of the positive electrode current collectors from which the positive electrode mixture was separated for the measurement of the porosity, the positive electrode current collectors of Samples No. 1 to No. 7 were washed. The positive electrode current collectors 1 and 1A of the washed samples No. 1 to No. 7 are cut with scissors along the diagonal line D shown in FIGS. 1 and 3, respectively, and are shown in FIGS. 2 and 4. , Divided bodies 2 and 2A in which ears are present were obtained. In the split body 2 in which the ears are present, the first portion 21 separated by the reference line K has 13 cut surfaces of the middle bone 112. In the split body 2A in which the ears are present, the first portion 21A divided by the reference line K has a total of 13 cut surfaces of the middle bones 112a and 112b.

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

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 (the 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 result of sample No. 1, FIG. 6 shows the result of sample No. 2, FIG. 7 shows the result of sample No. 3, FIG. 8 shows the result of sample No. 4, and FIG. 9 shows the result of sample No. 9. The result of 5 is shown, FIG. 10 shows the result of sample No. 6, and FIG. 11 shows the result of sample No. 7.

As shown in FIG. 5, in sample No. 1, all plots could be approximated to two straight lines T1 and T2 having different slopes with x = H (value between X8 and X9) as an intersection. 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. The results are shown in Table 8.

As shown in Table 8, the ratio A / B of sample No. 1 was 0.31.
Further, as shown in FIGS. 6 to 10, in Samples No. 2 to No. 6, all the plots have two different slopes with x = H (a value between X9 and X10) as an intersection. It was possible to approximate the 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. 50, the ratio A / B of sample No. 5 was 0.55, and the ratio A / B of sample No. 6 was 0.65.
Further, as shown in FIG. 11, in sample No. 7, all plots could be approximated to two straight lines T1 and T2 having different slopes with x = H (value of X10) as an intersection. 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 sample No. 1 to No. 35 liquid lead-acid batteries were subjected to a life test using the EUCAR power assist profile. The charge / discharge pattern of one cycle of this test is shown in FIG. C ₂ is a 2-hour rate capacity. In this charge / discharge pattern, there is a deep discharge in the partially charged state.
Further, after performing this life test for 100 cycles, the specific gravity of the electrolytic solution was measured at the upper part and the lower part of the electric tank using an optical hydrometer, and the difference in the upper and lower specific densities was calculated from these measured values.
The results of these tests are shown in Tables 15 and 16 along with the configuration of the grid-like substrate for each sample. Table 15 shows the difference in vertical specific density and the life test for samples No. 1 to No. 7 in which the porosity of the positive electrode active material of the positive electrode mixture is the same and the resistance value ratio A / B of the positive electrode current collector is different at 40%. It is a summary of the results. Table 16 summarizes all the test results of Samples No. 1 to No. 35 so that the difference can be seen when the resistance ratio A / B is the same and the porosity of the positive electrode active material of the positive electrode mixture is different. Is.

As can be seen from Table 15, the No. 1 and No. 6 liquid lead-acid batteries that do not satisfy 0.35 ≦ A / B ≦ 0.55 have a difference in the vertical specific gravity of the electrolytic solution of 0.070 and 0.040. In contrast, the liquid lead-acid batteries No. 2 to No. 5 and No. 7 satisfying 0.35 ≤ A / B ≤ 0.55 had a difference in the vertical specific gravity of the electrolytic solution of 0.005 to 0. It was as small as 015. Further, the life of the No. 1 and No. 6 liquid lead-acid batteries that do not satisfy 0.35 ≦ A / B ≦ 0.55 was 8000 to 8500 cycles, whereas the life was 0.35 ≦ A / B. The life of the liquid lead-acid batteries No. 2 to No. 5 and No. 7 satisfying ≦ 0.55 was as long as 17,000 to 22,000 cycles.
From the results in Table 15, the liquid lead-acid battery having a positive electrode current collector satisfying 0.35 ≦ A / B ≦ 0.55 and having a porosity of the positive electrode active material of the positive electrode mixture of 40% is in a partially charged state. It was confirmed that the stratification of the electrolytic solution was suppressed and the life of the electrolytic solution could be extended when used in the above.

Furthermore, the following can be seen from Table 16.
Samples No. 2 to No. 5, No. 7, No. 13, and No. 14 satisfying 0.35 ≦ A / B ≦ 0.55 and having a porosity of 35% or more and 55% or less of the positive electrode active material. , No.17, No.18, No.21, No.22, No.25, No.26, No.33 and No.34 liquid lead-acid batteries have a difference in the vertical specific gravity of the electrolyte of 0.005 to 5. It was as small as 0.030 and had a long life of 16000 to 22000 cycles.
On the other hand, the liquid lead-acid batteries of Samples No. 1 and No. 8 to No. 11 and Samples No. 6 and No. 28 to No. 31 that do not satisfy 0.35 ≦ A / B ≦ 0.55 are The difference in the vertical specific gravity of the electrolytic solution was as large as 0.035 to 0.080, and the life was as short as 7500 to 9900 cycles.
Further, the liquids of Samples No. 12, No. 16, No. 20, No. 24 and No. 32, which satisfy 0.35 ≦ A / B ≦ 0.55 but have a porosity of 30% of the positive electrode active material. The lead-acid battery had a large difference in the vertical specific gravity of the electrolytic solution of 0.035 to 0.055, and had a life of 9400 to 9900 cycles. Further, the liquids of Samples No.15, No.19, No.23, No.27 and No.35 which satisfy 0.35 ≦ A / B ≦ 0.55 but have a porosity of 60% of the positive electrode active material. The lead-acid battery had a small difference in the vertical specific gravity of the electrolytic solution of 0.004 to 0.008, but had a life of 9600 to 9900 cycles.

The reason for this result can be estimated as follows.
First, in a liquid lead-acid battery in which the porosity of the positive electrode active material is 30% even if 0.35 ≦ A / B ≦ 0.55 is satisfied, the amount of gas generated on the positive electrode plate in the partially charged state is determined. It is considered that the amount of the electrolytic solution was not required for sufficient stirring and the effect of suppressing stratification was insufficient, so that the difference in the vertical specific gravity of the electrolytic solution was large and the effect of improving the life was not so great. Next, in a liquid lead-acid battery in which 0.35 ≦ A / B ≦ 0.55 is satisfied and the porosity of the positive electrode active material is 60%, the positive electrode active material is softened, which causes the positive electrode active material to fall off. Therefore, it is considered that the effect of improving the life was not so much obtained.

As described above, from the results in Table 16, a liquid having a positive electrode current collector satisfying 0.35 ≦ A / B ≦ 0.55 and having a porosity of the positive electrode active material of the positive electrode mixture of 35% or more and 55% or less. It was confirmed that when the lead-acid battery is used in a partially charged state, the stratification of the electrolytic solution is suppressed and the life of the lead-acid battery can be extended.

1 Positive current collector 1A Positive current collector 11 Lattice substrate 11A Lattice substrate 12 Ear 111 Upper bone 112 Middle bone 112a Middle bone 112b Middle bone 2 Split body with ears 2A Split body with ears 21 First Part 21A First part 22 Second part 22A Second part

Claims (1)

A liquid lead-acid battery provided with a positive electrode current collector and a positive electrode plate having a positive electrode mixture.
The positive electrode current collector has a rectangular grid-like substrate and ears continuous to the grid-like substrate.
The positive electrode mixture is held on the grid-like substrate, and the positive electrode mixture is held.
The grid-like substrate has an upper bone along one side of the rectangle and a plurality of middle bones connected to the upper bone and located below the upper bone.
The ear protrudes upward from a position deviated from the center of the one side of the upper bone to one side.
Of the splits formed by cutting the positive current collector along the diagonal line passing through the corner on one side of the rectangle, the split in which the ear is present is the center of the ear on the boundary line with the upper bone. It is divided into a first part and a second part by a reference line passing through the point P and perpendicular to the upper bone, and the first part has a larger area than the second part.
On a coordinate plane in which both the x-axis and the y-axis are linear scales, the y-coordinates are each resistance value Rn between each cut surface Cn of the plurality of middle bones and the center point P in the first portion. All plots made with each distance Xn between the center point of each cut plane Cn and the center point P as the x coordinate can be approximated to two straight lines having different slopes with x = H as the intersection.
The ratio A / B by the average value A of each resistance value Rn at each distance Xn where x <H and the average value B of each resistance value Rn at each distance Xn where x ≧ H is 0.35. More than 0.55 or less
A liquid lead-acid battery characterized in that the porosity of the positive electrode active material of the positive electrode mixture is 35% or more and 55% or less.

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