JP6998441B2 - Liquid lead-acid battery - Google Patents

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 (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 acceptance becomes low and the utilization efficiency of regenerative energy decreases. It is said that it is desirable.

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 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 metallic 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 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 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 accommodation space and the accommodation space for accommodating the electrode plates are separately described. It is described that a communication flow path for communication is provided at the lower part. 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 a positive electrode mixture is held in a positive electrode current collector and a negative electrode plate in which a negative electrode mixture is held in a negative electrode current collector. The positive electrode current collector and the negative electrode current collector have a rectangular grid-like substrate and continuous ears on the grid-like substrate, as shown in FIG. 1 of Patent Document 2, for example. 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 group of electrode plates in which a positive electrode plate having a positive electrode current collector and a positive electrode mixture and a negative electrode plate having a negative electrode current collector and a negative electrode mixture are alternately laminated via a separator, and an electrolytic solution. It is a liquid lead-acid battery equipped with dilute sulfuric acid. The positive electrode current collector has a rectangular grid-like substrate and a continuous ear 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 divisions 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 division in which the ear exists is the upper bone of the ear. It is divided into a first part and a second part by a reference line K passing through the center point P on the boundary line and perpendicular to the upper bone, and the first part has a larger area than the second part.

(3) In the coordinate plane where 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 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, and x <H. When 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 separator has a film-like base portion, and the tensile fracture stress in the vertical direction of the base portion is larger than the tensile fracture stress in the horizontal direction.
The above-mentioned "vertical direction" is equal to the vertical direction of the electrode plate group when the positive electrode plate and the negative electrode plate are laminated via the separator, and the upper direction of the electrode plate group is that is, the upper part of the positive electrode current collector. Refers to the side where the bone is located. The above-mentioned "horizontal direction" is a direction orthogonal to the vertical direction, and is also a direction orthogonal to the laminating direction when the positive electrode plate and the negative electrode plate are laminated, that is, equal to the width direction of the positive electrode plate and the negative electrode plate. .. Further, the above-mentioned tensile fracture stress is measured according to the test method described in JIS K 7161 standard (plastic-test method for tensile properties).

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 storage battery of 1st Embodiment has. FIG. 3 is a front view showing a split body having ears, which is 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 storage battery of the 2nd Embodiment has. FIG. 3 is a front view showing a split body having ears, which is 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 the 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 the 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 the 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 the 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 the 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 a continuous ear on the grid-like substrate, and the positive electrode mixture is held on the grid-like substrate. 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 a continuous ear on 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 overlapped with the negative electrode plate.
The separator has at least a film-like base. The tensile fracture stress in the vertical direction of the base portion is larger than the tensile fracture stress in the horizontal direction. It is preferable that fold-shaped ribs having an appropriate height and width are formed on the surface of the base portion facing the positive electrode plate. By forming ribs on the base portion, even when the electrode plates are stored in the cell chamber in a compressed state, the surface of the positive electrode plate and the base portion are separated from each other to secure the flow path of the electrolytic solution and to secure the flow path of the electrolytic solution. Corrosion of the base portion due to the positive electrode plate during charging can be suppressed. The rib may also be formed on the surface facing the negative electrode plate.

The shape of the separator is not particularly limited, and may be a bag shape capable of accommodating the positive electrode plate or the negative electrode plate, or the film-like material may be bent into a U shape to sandwich the positive electrode plate or the negative electrode plate. It may be in the form of a film capable of.
Further, each electrode plate group includes a positive electrode strap and a negative electrode strap that connect a plurality of positive electrode plates and negative electrode plates 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 column, a positive electrode pole pillar and a negative electrode pole pillar 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 column 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 a small piece portion.

[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 to the grid-like substrate 11, and a 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 shifted to one side (right side in FIG. 1) from the center of one side of the upper bone 111.

FIG. 2 shows the divided bodies having ears among the divided bodies generated 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. 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 with the upper bone 111 of the ear 12 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 a cut surface of 13 middle bones 112. On the coordinate plane where both the x-axis and y-axis are linear scales, the resistance values R1 to R13 between the 13 cut planes C1 to C13 and the center point P are the y coordinates, and the center of each cut plane C1 to C13. When the distances X1 to X13 between the point and the center point P are plotted as x-coordinates, 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, and it is 0.85 mm or more and 1.00 mm or less.
The positive electrode current collector 1 can be obtained by a usual method such as a punching method, an expanding method, and 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 an ear 12 continuous to 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 shifted to one side (right side in FIG. 3) from the center of one side of the upper bone 111.

FIG. 4 shows the divided bodies having ears among the divided bodies generated 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 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 with 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 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 the coordinate plane where both the x-axis and y-axis are linear scales, the resistance values R1 to R13 between the 13 cut planes C1 to C13 and the center point P are y-coordinates, and the center of each cut plane C1 to C13. When the distances X1 to X13 between the point and the center point P are plotted as x-coordinates, 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. The thickness of the middle bone 112b is 1.15 mm or more and 1.25 mm or less, and is 75 mm or more and 0.85 mm or less.
The positive electrode current collector 1A can be obtained by a usual method such as a punching method, an expanding method, and a gravity casting 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 to the ear of the positive electrode collector is significantly larger than the resistance value of the path from the upper part to the ear, so that the resistance value at the lower part of the positive electrode plate is significantly higher. The charge / discharge reaction is less likely 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 having a positive electrode current collector ratio A / B of more than 0.55, the charge / discharge reaction is less likely to proceed in the entire positive electrode plate, so that the amount of gas generated is the electrolytic solution stirring action in a partially charged state. Not enough to get.

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, in the liquid lead-acid battery using the positive electrode current collector 1 of the first embodiment and the liquid lead-acid battery using the positive electrode current collector 1A of the second embodiment, the longitudinal tensile fracture stress of the base portion of the separator is obtained. However, when it is larger than the tensile fracture stress in the lateral direction, the extrusion direction when the molten material is extruded to form a film at the time of separator molding coincides with the vertical direction of the electrode plate group. This is because the tensile fracture stress in the extrusion direction during separator molding is larger than the tensile fracture stress in the direction orthogonal to it. Fine grooves are formed on the surface of the base portion of the separator along the extrusion direction at the time of molding. That is, when the longitudinal tensile fracture stress of the separator is larger than the lateral tensile stress of the separator, the vertical direction of the electrode plate group and the direction of the fine groove at the base of the separator coincide with each other. The gas generated from the above can easily escape to the upper side. Therefore, by stirring the electrolytic solution, stratification of the electrolytic solution is further suppressed, and the life of the electrolytic solution can be extended.

On the other hand, when the lead-acid battery has a long life, the positive electrode plate inevitably corrodes and expands remarkably at the end of the life. When the longitudinal tensile fracture stress of the separator base is 10 MPa or more and 30 MPa or less, and the lateral tensile fracture stress of the separator base is 1 MPa or more and 9 MPa or less, the positive electrode plate expands and pulls the separator. In addition, it is possible to suppress the breakage of the separator and the sudden death of the lead storage battery. If the longitudinal tensile fracture stress of the base portion is less than 14 MPa and the lateral tensile fracture stress is less than 1 MPa, it is not possible to prevent the separator from breaking when the electrode plate expands. The reason why the tensile fracture stress in the vertical direction needs to be larger than the tensile fracture stress in the horizontal direction is that in a liquid lead-acid battery having a general vertically long positive electrode lattice, the expansion due to corrosion is vertical with respect to the horizontal direction. This is because the direction is larger. On the other hand, when the tensile fracture stress in the vertical direction of the base portion is larger than 30 MPa, the thickness of the base portion of the separator increases and the fluidity of the electrolytic solution decreases, so that stratification proceeds. On the other hand, even if the tensile fracture stress in the lateral direction exceeds 9 MPa, the internal resistance does not increase remarkably, but in such a separator, since grooves are hardly formed during extrusion, the vertical direction of the electrode plate group It is not possible to obtain the effect of improving the gas release in. If the values of the longitudinal tensile fracture stress and the lateral tensile fracture stress of the base portion of the separator change before and after the chemical formation, the values after the chemical formation are adopted.

[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 (after chemical conversion) 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 located 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 division in which the ear is present is the center point P on the boundary line with the upper bone of the ear. 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 surface 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.

[Making test batteries]
Sample No. 1 to No. 49 liquid lead-acid batteries were produced as liquid lead-acid batteries having the same structure as the liquid lead-acid battery of the embodiment.
The liquid lead-acid batteries of Samples No. 1 to No. 49 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. 13 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. 13 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.
Samples No. 14 to No. 19 have the same shape as the sample No. 2 in the shape of the grid-like substrate of the positive electrode current collector. Samples No. 2 and Nos. 14 to 19 differ in the longitudinal tensile fracture stress of the base of the separator and the lateral tensile fracture stress of the base of the separator, but all other points have the same configuration. Have.

Samples No. 20 to No. 25 have the same shape of the grid-like substrate of the positive electrode current collector as that of sample No. 3. Samples No. 3 and No. 20 to No. 25 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.
Samples No. 26 to No. 31 have the same shape of the grid-like substrate of the positive electrode current collector as sample No. 4. Samples No. 4 and No. 26 to No. 31 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.

Samples No. 32 to No. 37 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. 32 to No. 37 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.
Samples No. 38 to No. 43 have the same shape of the grid-like substrate of the positive electrode current collector as that of sample No. 6. Samples No. 5 and No. 38 to No. 43 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.
Samples No. 44 to No. 49 have the same shape of the grid-like substrate of the positive electrode current collector as that of sample No. 7. Samples No. 7 and No. 44 to No. 49 have different longitudinal tensile fracture stresses at the base of the separator and lateral tensile fracture stress at the base of the separator, but all other points have the same configuration. Has.

<Sample No.1 and Samples No.8 to No.13>
The liquid lead-acid batteries of Sample No. 1 and Samples No. 8 to No. 13 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.

First, a punching process for a strip-shaped lead alloy sheet (size corresponding to a plurality of positive electrode current collectors 1), a filling process for a positive electrode active material paste (a kneaded product containing a positive electrode mixture) on a lattice-shaped substrate 11. By performing the preheating drying step, the aging drying step, and the cutting step, a positive electrode plate before chemical conversion 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 collector having the same shape as the positive electrode collector 1 shown in FIG. 1, but in the negative electrode collector, the size S1 = 114.0 mm, the size S2 = 108.0 mm, and the size 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. 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, 7 sheets of the obtained pre-chemical electrode plates put in a polyethylene bag-shaped separator and 6 sheets of the obtained pre-chemical positive electrode plates were alternately laminated to obtain a laminate. Next, a group of electrode plates was obtained by forming a strap, an intermediate electrode column, and a terminal electrode column on the positive electrode plate and the negative electrode plate of each laminate using a COS (cast-on-strap) type casting apparatus.

The bag-shaped separator has a film-shaped base portion having a thickness of 0.2 mm and a plurality of ribs protruding from the surface of the base portion and having a protruding height of 0.5 mm. Further, the bag-shaped separator is formed into a bag shape by folding a film-like material having a width of 110 mm and a length of 230 mm so that the surface on the side where the ribs are formed faces outward, and gear-sealing both side edges. It was done. As a result of measurement in accordance with the test method described in JIS K 7161 standard (Plastic-tensile property test method), the longitudinal / horizontal tensile fracture stress of the base of the separator was No. 1 at 15 MPa / 6 MPa. No. 8 is 7 MPa / 1 MPa, No. 9 is 10 MPa / 0.2 MPa, No. 10 is 10 MPa / 1 MPa, No. 11 is 30 MPa / 9 MPa, No. 12 is 30 MPa / 11 MPa, and No. 13 is 35 MPa / 9 MPa. there were. A tensile tester (TG20KN manufactured by Minebea Co., Ltd.) was used for the tensile fracture stress test.

Six of these electrode plates are prepared and placed in each cell chamber of the battery chamber, resistance welding of intermediate pole columns between adjacent cell chambers, heat welding of the battery chamber and lid, and 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 formation by a usual method, the specific density after the electric tank chemical formation was set to 1.285 (20 ° C. conversion value). In this way, sample No. 1 and No. 8 to No. 13 liquid lead-acid batteries were obtained.

<Sample No. 2 and Samples No. 14 to No. 19>
The liquid lead-acid batteries of Sample No. 2 and Samples No. 14 to No. 19 have the positive electrode current collector 1 having the shape shown in FIG. 1, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). Is 1.00 mm. Other than that, sample No. 2 is the same as sample No. 1, sample No. 14 is the same as sample No. 8, sample No. 15 is the same as sample No. 9, and the sample. No. 16 is the same as sample No. 10, sample No. 17 is the same as sample No. 11, sample No. 18 is the same as sample No. 12, and sample No. 19 is sample No. 13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the thickness of the central bone 112 of the positive electrode current collector used is different. Battery chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 2 and Samples No. 14 to No. 19.

<Sample No.3 and Samples No.20 to No.25>
The liquid lead-acid batteries of Sample No. 3 and Samples No. 20 to No. 25 have the positive electrode current collector 1 having the shape shown in FIG. 1, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). Is 0.95 mm. Other than that, sample No. 3 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 the sample. No.22 is the same as sample No.10, sample No.23 is the same as sample No.11, sample No.24 is the same as sample No.12, and sample No.25 is sample No.13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the thickness of the central bone 112 of the positive electrode current collector used is different. Battery chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 3 and Samples No. 20 to No. 25.

<Sample No.4 and Samples No.26 to No.31>
The liquid lead-acid batteries of Sample No. 4 and Samples No. 26 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). Is 0.90 mm. Other than that, sample No. 4 is the same as sample No. 1, sample No. 26 is the same as sample No. 8, sample No. 27 is the same as sample No. 9, and the sample. No. 28 is the same as sample No. 10, sample No. 29 is the same as sample No. 11, sample No. 30 is the same as sample No. 12, and sample No. 31 is sample No. 13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the thickness of the central bone 112 of the positive electrode current collector used is different. Battery chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 4 and Samples No. 26 to No. 31.

<Sample No.5 and Samples No.32 to No.37>
The liquid lead-acid batteries of Sample No. 5 and Samples No. 32 to No. 37 have the positive electrode current collector 1 having the shape shown in FIG. 1, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). Is 0.85 mm. Other than that, sample No. 5 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 the sample. No.34 is the same as sample No.10, sample No.35 is the same as sample No.11, sample No.36 is the same as sample No.12, and sample No.37 is sample No.13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the thickness of the central bone 112 of the positive electrode current collector used is different. Battery chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 5 and Samples No. 32 to No. 37.

<Sample No. 6 and Samples No. 38 to No. 43>
The liquid lead-acid batteries of Sample No. 6 and Samples No. 38 to No. 43 have the positive electrode current collector 1 having the shape shown in FIG. 1, and the thickness of the middle bone 112 (cross-sectional area perpendicular to the longitudinal direction). Is 0.75 mm. Other than that, sample No. 6 is the same as sample No. 1, sample No. 38 is the same as sample No. 8, sample No. 39 is the same as sample No. 9, and the sample. No. 40 is the same as sample No. 10, sample No. 41 is the same as sample No. 11, sample No. 42 is the same as sample No. 12, and sample No. 43 is sample No. 13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the thickness of the central bone 112 of the positive electrode current collector used is different. Battery chemicals were carried out to obtain liquid lead-acid batteries of Sample No. 6 and Samples No. 38 to No. 43.

<Sample No.7 and Samples No.44 to No.49>
The liquid lead-acid batteries of Sample No. 7 and Samples No. 44 to No. 49 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, the thickness of the middle bone 112a (cross-sectional area perpendicular to the longitudinal direction) is 0.80 mm, and the thickness of the middle bone 112b is 1.20 mm.
Other than that, sample No. 7 is the same as sample No. 1, sample No. 44 is the same as sample No. 8, sample No. 45 is the same as sample No. 9, and sample. No.46 is the same as sample No.10, sample No.47 is the same as sample No.11, sample No.48 is the same as sample No.12, and sample No.49 is sample No.13. Is the same as.
After assembling the D23 type liquid lead-acid battery for ISS vehicles by the same method as sample No. 1 and samples No. 8 to No. 13 except that the positive electrode current collector 1A in FIG. 3 was used, the battery tank was formed. Then, sample No. 7 and samples No. 44 to No. 49 liquid lead-acid batteries were obtained.

[Measurement of each resistance value of the cut surface of the split body]
First, the obtained sample No. 1 to No. 7 liquid lead-acid batteries were disassembled, and the positive electrode active material was removed from the positive electrode plate (after chemical conversion) randomly selected for each sample and washed. The washed positive electrode current collectors 1 and 1A of the 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. , A split body 2, 2A in which ears are present was 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 surface C1 to C13 of each middle bone is measured three times 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, the measurement results were plotted for each sample on a coordinate plane in which both the x-axis and the y-axis are linear scales, with the resistance value Rn (mean 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 No. 1, FIG. 6 shows the result of No. 2, FIG. 7 shows the result of No. 3, FIG. 8 shows the result of No. 4, and FIG. 9 shows the result of No. 5. FIG. 10 shows the result of No. 6, and FIG. 11 shows the result of 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. (Mean 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 (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. (Mean 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. (Mean 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. 49 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 vertical specific gravity of samples No. 1 to No. 7 having the same vertical / horizontal tensile fracture stress of the separator base and different resistance values A / B of the positive electrode current collectors at 15 MPa / 6 MPa. This is a summary of the differences and the results of the life test. Table 16 shows the difference between all the test results of Samples No. 1 to No. 49 when the resistance ratio A / B is the same and the longitudinal / lateral tensile fracture stress of the base of the separator is different. It is summarized in.

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 between 0.070 and 0.040. In contrast, the 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 0.015. It was small. 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, a liquid lead-acid battery provided with a positive electrode current collector satisfying 0.35 ≤ A / B ≤ 0.55 and having a longitudinal / lateral tensile fracture stress of the separator base portion of 15 MPa / 6 MPa. It was confirmed that when used in a partially charged state, the stratification of the electrolytic solution is suppressed and the life can be extended.

Furthermore, the following can be seen from Table 16.
Satisfying 0.35 ≤ A / B ≤ 0.55, the longitudinal tensile fracture stress of the separator base is 10 MPa or more and 30 MPa or less, and the lateral tensile fracture stress of the separator base is 1 MPa or more and 9 MPa or less. Samples No.2 to No.5, No.7, No.16, No.17, No.22, No.23, No.28, No.29, No.34, No.35, No.46 and The No. 47 liquid lead-acid battery had a small difference in vertical specific gravity of the electrolytic solution of 0.003 to 0.017 and a long life of 15200 to 23700 cycles.
On the other hand, the liquid lead-acid batteries of Samples No. 1 and No. 8 to No. 13 and No. 6 and No. 38 to No. 43 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 0.034 to 0.082, and the life was as short as 5400 to 8900 cycles.

Further, samples No.14, No.20, No.26, No.32, No. which satisfy 0.35≤A / B≤0.55 but have a longitudinal tensile fracture stress of 7 MPa at the base of the separator. .44 liquid lead-acid batteries and sample No.15, No.21, No.27, No.33, No.45 liquid lead-acid batteries with a lateral tensile fracture stress of 0.2 MPa at the base of the separator. The difference in the vertical specific gravity of the electrolytic solution was as small as 0.005 to 0.021, but the life was as small as 5200 to 7800 cycles. When these samples were disassembled and observed after the test, in the liquid lead-acid battery having a short life, a part of the positive electrode lattice that was corroded and broken penetrated the separator, and traces of contact short circuit with the negative electrode plate were observed. .. Further, samples No. 19, No. 25, No. 31, No. 37, No. which satisfy 0.35 ≦ A / B ≦ 0.55 but have a longitudinal tensile fracture stress of 35 MPa at the base of the separator. The .49 liquid lead-acid batteries and the sample No. 18, No. 24, No. 30, No. 36, and No. 48 liquid lead-acid batteries in which the lateral tensile fracture stress of the base of the separator is 11 MPa are The difference in the vertical specific gravity of the electrolytic solution was as large as 0.035 to 0.042, and the life was 11000 to 14700 cycles, which was less than 15000 cycles. When these samples were disassembled after the test and investigated, it was observed that a large number of bubbles were retained between the positive electrode plate and the negative electrode plate with the separator interposed therebetween. In addition, grayish white lead sulfate crystals were observed on the surface of the negative electrode plate, indicating that sulfation was progressing.

The reason for this result can be estimated as follows.
First, even if 0.35 ≤ A / B ≤ 0.55 is satisfied, the longitudinal tensile fracture stress of the base portion of the separator is 7 MPa, and the lateral tensile fracture stress of the base portion of the separator and the liquid lead storage battery is In a liquid lead storage battery with a voltage of 0.2 MPa, when the separator is pulled by deformation of the positive electrode plate expanded (grown) due to corrosion at the end of its life, it is not possible to prevent the base of the separator from tearing, and the separator cannot be prevented. It is considered that the life improvement effect was not so much obtained as compared with the sample in which the longitudinal tensile fracture stress of the base portion of the separator was 10 MPa or more and the sample in which the lateral tensile fracture stress of the base portion of the separator was 1 MPa or more. ..

Next, even if 0.35 ≤ A / B ≤ 0.55 is satisfied, the longitudinal tensile fracture stress of the base portion of the separator is 35 MPa, and the lateral tensile fracture stress of the base portion of the separator and the liquid lead-acid battery. In a liquid lead-acid battery having a stress of 11 MPa, the fluidity of the electrolytic solution decreases due to the increase in the thickness of the base portion of the separator, so that the gas generated on the positive electrode plate in the partially charged state flows to the outside of the electrode plate group. It becomes difficult to be discharged. Along with this, it is considered that the electrolytic solution was not sufficiently agitated and stratification proceeded, so that sulfation occurred and the effect of improving the life was not so much obtained. From the above results, a positive electrode current collector satisfying 0.35 ≤ A / B ≤ 0.55 is provided, and the longitudinal tensile fracture stress of the base portion of the separator is higher than the lateral tensile fracture stress of the base portion of the separator. It was confirmed that the large liquid lead-acid battery can prolong its life by suppressing the stratification of the electrolytic solution when it is used in a partially charged state. Further, when the longitudinal tensile fracture stress of the base portion of the separator is 10 MPa or more and 30 MPa or less and the lateral tensile fracture stress of the base portion of the separator is 1 MPa or more and 9 MPa or less, stratification is suppressed and the life is extended. Even when the positive electrode plate expands and pulls the separator at the end of the life of the liquid lead-acid battery, the breakage of the separator can be suppressed and the sudden death of the lead-acid battery can be suppressed.

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 (2)

A group of electrode plates in which a positive electrode plate having a positive electrode current collector and a positive electrode mixture and a negative electrode plate having a negative electrode current collector and a negative electrode mixture are alternately laminated via a separator, and dilute sulfuric acid as an electrolytic solution are used. It is a liquid lead-acid battery equipped with
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 offset unilaterally from the center of the one side of the upper bone.
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 division 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 resistance value Rn between each cut surface Cn of the plurality of central bones and the center point P in the first portion is set in the y coordinate. 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
The separator has a film-shaped base portion, and the base portion is a liquid lead-acid battery characterized in that the tensile fracture stress in the vertical direction is larger than the tensile fracture stress in the horizontal direction. The separator has a film-like base portion, and the base portion has a longitudinal tensile fracture stress of 10 MPa or more and 30 MPa or less, and a lateral tensile fracture stress of 1 MPa or more and 9 MPa or less. Liquid lead-acid battery.

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