JP7347439B2 - lead acid battery - Google Patents

Description

The present invention relates to lead acid batteries.

Lead-acid batteries are used in a variety of applications, including automotive and industrial applications. A lead-acid battery includes an electrode group in which positive electrode plates and negative electrode plates are alternately stacked with separators in between. The electrode plate is composed of a current collector and an electrode material held by the current collector.

Patent Document 1 discloses a lead lattice plate formed by press-punching a rolled lead alloy plate, in which the thickness of the internal vertical and horizontal bars is thinner than the thickness of the outer frame, and the outer frame has a thickness of 0. We have proposed a lead lattice plate for lead-acid batteries characterized by having a thickness of 8 to 1.5 mm and an internal crosspiece thickness of 0.6 to 0.8 mm. In addition, the inner frame of the lead lattice plate obtained by press-punching a rolled lead alloy plate with a thickness of 1.2 to 1.5 mm was deformed in the thickness direction to form internal vertical and horizontal crosspieces. We have proposed a lead lattice plate for lead-acid batteries, which is characterized by having a thickness set in the range of 0.6 to 0.8 mm.

In the above lead grid plate, the thickness of the inner frame is thinner than that of the outer frame, and the active material holding surface is recessed in a stepped manner relative to the outer frame, so the unit lead grid plate The amount of active material retained per unit can be significantly increased compared to a lead grid plate of uniform thickness, and the retention power of the active material can also be greatly improved without roughening the surface of the lead grid plate. It becomes.

Japanese Unexamined Patent Publication No. 51-60936

If the thickness of the internal vertical and horizontal crosspieces is made thinner than the thickness of the outer frame, the retention power of the active material can be improved without roughening the surface of the lead grid plate, and the amount of active material retained can be further increased. It is said that it can increase the

However, even if the holding power of the active material is improved, unless the corrosion of the current collector is suppressed, it is difficult to suppress the elongation of the current collector, and the electrode material may fall off. When the electrode material falls off, the battery capacity inevitably decreases.

One aspect of the present invention is a lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrolytic solution, wherein the positive electrode plate and the negative electrode plate each include a current collector and an electrode held by the current collector. The frame bone has an ear provided on the frame bone and an inner bone inside the frame bone, and the frame bone has an upper element continuous with the ear, a lower element facing the upper element, and an upper element. a pair of side elements connecting the lower element, wherein the inner bone includes a vertical bone extending in a first direction from the upper element to the lower element; and a vertical bone extending in a first direction from one side element to the other side element. A striped pattern of metal fibrous tissue is seen in a cross section perpendicular to the first direction of the longitudinal bone, and in an outer peripheral area of the cross section, the fibrous tissue extends in the cross section. It is composed of a first portion extending along the contour and a second portion other than the first portion, and the proportion of the length of the contour corresponding to the second portion of the total length of the cross-sectional contour is less than 50%. and the ratio t _b / _{t a} of the thickness t _b of the inner bone to the thickness t a of the ear is 60% or more and 97% or less.

According to the present invention, the battery capacity in a 5-hour rate discharge capacity test of a lead-acid battery can be increased.

1 is a plan view showing the appearance of a current collector for a lead-acid battery according to an embodiment of the present invention. FIG. 3 is a plan view showing the appearance of a current collector for a lead-acid battery according to another embodiment of the present invention. It is a cross-sectional photograph perpendicular to the first direction of a longitudinal bone. It is a conceptual diagram of cross section C. This is a cross-sectional photograph of an inner bone in which a cross-section of fibrous tissue can be seen. FIG. 3 is a conceptual cross-sectional diagram showing the progress of corrosion of the inner bone. 1 is a perspective view showing the appearance of a lead-acid battery according to an embodiment of the present invention. It is a graph which shows the difference by a 2nd partial ratio about the relationship between tb _{/ ta} and 5 hour rate discharge capacity of the lead-acid battery based on one Embodiment of this invention. 2 is a graph showing the relationship between t _b /t _a of a lead-acid battery according to an embodiment of the present invention and the period until the vertical elongation of the positive electrode current collector reaches 7% of the initial ratio in an overcharged state. It is a graph showing the ratio of the 5-hour rate discharge capacity when pressure is applied to the 5-hour rate discharge capacity when pressure is not applied to the electrode group of the lead-acid battery according to one embodiment of the present invention. It is a graph which shows the relationship between the pull-out load of the electrode group of the lead acid battery based on one Embodiment of this invention, and the ratio of 5 hour rate discharge capacity. 2 is a graph showing the ratio of the 5-hour rate discharge capacity when Sb ₂ O ₃ is added to the 5-hour rate discharge capacity when Sb ₂ O ₃ is not added to the positive electrode material of the lead-acid battery according to an embodiment of the present invention.

A lead-acid battery according to one aspect of the present invention includes a positive electrode plate, a negative electrode plate, and an electrolyte. The positive electrode plate and the negative electrode plate each include a current collector and an electrode material held by the current collector. The current collector has a frame bone, an ear provided on the frame bone, and an inner bone inside the frame bone. The inner bone may be mesh-like. The frame includes an upper element continuous with the ear, a lower element facing the upper element, and a pair of side elements connecting the upper element and the lower element. The internal bone includes a longitudinal bone extending in a first direction from the upper element to the lower element and a transverse bone extending in a second direction from one side element to the other side element. The first direction is a direction parallel to the side elements and the second direction is a direction parallel to the top and bottom elements. Note that the current collector is also referred to as a grid body. However, the skeleton of the current collector or the lattice body is not limited to a lattice shape or a mesh shape.

A striped pattern of metal fibrous tissue is seen in a cross section perpendicular to the first direction of the longitudinal bone, that is, a cross section parallel to the upper element and parallel to the thickness direction (hereinafter also referred to as cross section C). The outer peripheral region of the cross section C is composed of a first portion in which the fibrous structure (stripe direction) extends along the contour of the cross section C (hereinafter also referred to as contour C), and a second portion other than the first portion. ing.

Here, the ratio of the contour corresponding to the second portion (hereinafter also referred to as second contour portion) to the total length of the contour C (hereinafter also referred to as second portion ratio) is controlled to be less than 50%, and The ratio t _b /t _a of the inner bone thickness t _b to the ear thickness _{t a} is controlled to be 60% or more and 97% or less. When the second portion ratio is less than 50%, elongation of the current collector due to corrosion is significantly suppressed. When t _b /t _a is set to 60% or more and 97% or less, the surface of the current collector becomes susceptible to corrosion. By synergistically exerting these effects, it is possible to improve the battery capacity in a good 5-hour rate discharge capacity test. t _b /t _a is preferably 65% or more and 95% or less, more preferably 70% or more and 90% or less, even more preferably 75% or more and 85% or less.

The ear thickness _ta is the average length of the ear in the thickness direction. t _a may be, for example, 1.0 mm to 1.5 mm. The average length in the thickness direction of the ear may be the average value of the thickness at any three points located 2 mm or more inward from the periphery of the ear.

The thickness t _b of the inner bone is the average length of the grid body or the electrode plate in the thickness direction of the inner bone. The average value of the length in the thickness direction of the inner bone may be the average value of the thickness of the central part of the inner bone to be measured in the bone width direction. The internal bone to be measured is the longitudinal bone. The measurement positions are ⅓ position and ⅔ position from the upper end of the dimension in the first direction of the current collector excluding the ears and feet. If these positions correspond to intersections between vertical and horizontal bones, move the measurement positions slightly. Specifically, it is sufficient to calculate the average value of the measured values of 60% or more of the measurement positions of the vertical bone 1/3 from the upper end and 60% or more of the measurement positions of the vertical bone 2/3 from the upper end.

t _b may be, for example, 0.65 mm to 0.98 mm. When t _b is 0.65 mm or more, the effect of suppressing corrosion becomes greater, and when t b is 0.98 mm or less, the holding power of the electrode material by the current collector increases, making it easier to suppress the electrode material from falling off. Note that in the case of a relatively thick punched current collector with t _b of 1.5 mm or more, the proportion of the second contour portion in the contour C generally tends to be large. Even when the proportion of the second contour portion is large as described above, it is not difficult to reduce the second portion proportion to less than 50%, even to 40% or less, by press working or the like.

In the lead-acid battery according to one embodiment of the present invention, the current collector is preferably processed by applying pressure using a press or the like, for example. When t _b /t _a is less than 60%, the amount of elongation of the current collector after overcharging becomes large, which is not appropriate.

That is, the method for manufacturing a lead-acid battery includes the steps of preparing a current collector and obtaining a positive electrode plate or a negative electrode plate including the prepared current collector. Here, the step of preparing the current collector includes the step of preparing a rolled plate and punching the rolled plate to form an intermediate lattice body having a plurality of intermediate ribs formed in a lattice shape. and a step of press working the intermediate lattice body from the thickness direction of the intermediate lattice body to form at least a part of the inner bone. Furthermore, in the press working, at least one end in the bone width direction is made thinner in at least a part of the plurality of intermediate bones than in the center part in the bone width direction intersecting the extending direction of the intermediate bones, and the thickness of the ear is reduced. This includes deforming so that the ratio t _b /t _a of the thickness t _b of the central _portion to t a is 60% or more and 97% or less.

Each element of the current collector will be further explained below.
The longitudinal ribs may extend parallel to the side elements or may extend obliquely to the side elements. Further, the vertical bone may be straight or curved, or may have some bends. That is, the vertical bone only needs to extend so that the vector in the first direction is larger than the vector in the second direction.

The transverse bone may extend parallel to the upper or lower element, or may extend obliquely to the upper or lower element. Further, the transverse bone may be straight or curved, or may have some bends. That is, the transverse bone only needs to extend so that the vector toward the second direction is larger than the vector toward the first direction. The frame may be rectangular.

The contour of section C means a line corresponding to the outer surface of the longitudinal bone. The outer peripheral region of cross section C is a peripheral region along the outline of cross section C, and has a depth of at least 55 μm or more from a line corresponding to the outer surface, and preferably has a depth of 100 μm or more.

In the second portion, no striped pattern may be observed, or a striped pattern extending in the depth direction of the outer peripheral region may be observed. That is, a cross section perpendicular to the fiber length of the fibrous tissue is likely to be exposed on the outer surface of the second portion. When the second portion ratio is made smaller, the cross section perpendicular to the fiber length of the fibrous tissue is less likely to be exposed on the outer surface of the outer peripheral region of the cross section C.

A cross section perpendicular to the fiber length of the fibrous structure has many grain boundaries. Therefore, in the second portion, corrosion of the vertical bones tends to progress deeply in a wedge-like manner. As deep corrosion progresses, the elongation of the current collector tends to increase. On the other hand, in the first part, the corrosion of the vertical bones is shallow and tends to progress. The elongation of the current collector due to shallow corrosion is small. That is, even if the amount of corrosion is the same, the smaller the second fraction, the more difficult it is for corrosion to progress to a deep region of the current collector, the elongation of the current collector is suppressed, and the falling off of the electrode material is suppressed. By setting the second fraction to 40% or less, the elongation of the current collector is more significantly suppressed.

On the other hand, in the cross section perpendicular to the second direction of the transverse bone, that is, the cross section parallel to the side element and parallel to the thickness direction (hereinafter also referred to as cross section G), almost no striped pattern of metal fibrous tissue is visible. Generally, a cross section perpendicular to the fiber length of the fibrous tissue is seen. The outer circumferential region of cross section G generally corresponds to the second portion of cross section C over almost the entire circumference. In other words, the outer circumferential region of cross section G is composed of a fibrous structure extending in the second direction almost all around. Therefore, in the outer peripheral region of cross section G, the elongation of the current collector is suppressed even if the amount of corrosion is the same.

When the second fraction is less than 50% (preferably 40% or less), the degree of corrosion tends to be uniform throughout the inner bone. It is thought that such uniform corrosion suppresses uneven distribution of corroded parts and suppresses elongation of the current collector in one direction.

Here, the first part rate and the second part rate are intentionally controllable. Even if the vertical bone originally has a large second portion ratio, it is possible to deform the vertical bone so as to crush the second portion. For example, when deforming the vertical bone by press working, the first portion ratio can be arbitrarily controlled by the press speed, press pressure, mold shape, etc. That is, deforming the longitudinal bones by press working is not a sufficient condition for increasing the first portion ratio, and it is necessary to appropriately control the conditions of press working. When the first portion ratio becomes large, elongation of the current collector is suppressed, and falling off of the electrode material is suppressed.

In the first portion, the fibrous structure (in the direction of the stripes) extending along the contour of the outer peripheral region of the cross section C refers to the following state. First, the inside of the frame bone of the current collector is divided into three equal parts: an upper region on the upper element side of the frame bone, a lower region on the lower element side of the frame bone, and a middle region between the upper region and the lower region. Cut as shown. At this time, four rows of cross sections C perpendicular to the first direction (parallel to the upper element and parallel to the thickness direction) are formed in the plurality of longitudinal bones. That is, one row of cross sections C is formed in each of the upper region and the lower region, and two rows of cross sections C are formed in the middle region. If the dividing line into thirds corresponds to an intersection (node) between a vertical bone and a horizontal bone, the dividing line should be adjusted as a whole so that cross section C is formed in the vertical bone between the intersections. Alternatively, the current collector may be divided into three by partially moving it a little. Note that when dividing the inside of the frame bone of the current collector into three parts, the dimensions of the ears or feet are not taken into account.

Next, a plurality of cross sections C to be observed (more than 60% of the cross sections C included in the two columns) are selected from arbitrary two columns among the four columns. Among the outer circumferential regions of the selected cross section C, a portion where the stripes of the fibrous tissue form an angle of less than 45° with the outline of the cross section C is the first portion. Specifically, at any point P on the contour C of each cross section C, a tangent S1 to the point P is drawn, and a perpendicular L to the tangent S1 is drawn passing through the point P. Next, a tangent line S2 of the stripe that exists at a depth of 55 μm from point P on the perpendicular line L and intersects with the perpendicular line L is drawn at the intersection. When the angle θ between the tangent line S2 and the tangent line S1 is less than 45°, the point P constitutes a first contour portion corresponding to the first portion. Such observation is appropriately performed on the contour C, the length of the first contour portion is specified, and the ratio of the first contour portion to the total length of the contour C is determined as the first portion ratio. If the angle θ is greater than or equal to 45°, the point P constitutes the second portion. Even when it cannot be determined whether or not the point P constitutes the first contour portion, for example because the fibrous structure cannot be observed, the point P constitutes the second portion. The first partial ratio is determined in all the selected cross sections C, and the average value is calculated.

If the cut point is an intersection (node) between a vertical bone and a horizontal bone, the cross section may be removed and the average taken, or the cut position of the vertical bone may be shifted so that the node is off.

When forming the cross section C, a current collector before being filled with the electrode material may be used. Alternatively, a fully charged lead-acid battery can be dismantled, the electrode plates taken out, washed with water to remove the electrolyte, and then dried. Next, the electrode material is removed from the electrode plate, and the electrode material adhering to the surface of the current collector is removed using mannitol. After embedding the prepared current collector in a thermosetting resin so as to cover the entirety thereof and curing the resin, the current collector may be cut together with the cured resin. The state of the metal structure in cross section C can be observed by etching the cross section of the current collector and photographing it with a microscope.

In this specification, a fully charged state of a lead-acid battery means, in the case of a liquid type battery, a current (A) of 0.2 times the value (Ah) stated as the rated capacity in a water tank at 25°C ± 2°C. After performing constant current charging until reaching 2.5V/cell, constant current charging was performed for 2 hours at a current (A) that is 0.2 times the value (Ah) stated as the rated capacity. . In the case of a valve-controlled battery, a fully charged state is defined as a fully charged state at a current (A) of 0.2 times the value (Ah) stated as the rated capacity in an air tank at 25°C ± 2°C. Constant current and constant voltage charging was performed at 23 V/cell, and charging was completed when the charging current during constant voltage charging became 0.005 times the numerical value (Ah) stated as the rated capacity.
Note that the numerical value described as the rated capacity is a numerical value in Ah. The unit of current set based on the numerical value stated as the rated capacity is A.

The thickness of the first portion may be 55 μm or more. Furthermore, even if the outer peripheral region appears to be the first portion at first glance, if the thickness of the region where the striped pattern of fibrous tissue is observed is less than 55 μm, it is considered to be the second portion rather than the first portion. The first portion having a thickness of 55 μm or more has a sufficient effect of suppressing corrosion from penetrating inside. In this case, the inward penetration of corrosion tends to be highly uniform throughout the inner bone. Therefore, the elongation of the current collector is significantly suppressed, and the falling off of the electrode material is also significantly suppressed. From the viewpoint of further improving suppression of corrosion resistance of the vertical bones from penetrating into the inside, the thickness of the first portion is preferably 100 μm or more.

Note that a fully charged lead-acid battery refers to a fully charged lead-acid battery made of a chemical compound. Full charging of the lead-acid battery may be performed immediately after the formation, or after a period of time has elapsed since the formation. For example, after chemical formation, a lead-acid battery in use (preferably at the beginning of use) may be fully charged. A battery in the early stage of use refers to a battery that has not been used for much time and has hardly deteriorated.

The thickness of the first portion in cross section C may be measured as follows. First, a tangent S1 is drawn at an arbitrary point P1 on the first contour, and a perpendicular line L to the tangent S1 is drawn passing through the point P1. Next, at a point Px that moves on the perpendicular line L from point P1 to a depth of X μm, tangents S2 to the stripes that intersect with the perpendicular line L are continuously drawn. At this time, if the angle between the tangent line S1 and the tangent line S2 is continuously 45 degrees or less, it can be said that the thickness of the first portion directly below the point P1 is X μm or more.

The width of the inner bone may be, for example, 0.7 mm to 3 mm. The width of the inner bone is the width perpendicular to the length direction of the inner bone in the surface direction of the current collector or electrode plate. If the width of the inner bone is 0.7 mm or more, the effect of suppressing corrosion will be greater, and it will be easier to avoid disconnection of the inner bone even during overcharging. Moreover, if the width of the inner rib is 3 mm or less, the filling property of the electrode material into the current collector will be improved, and the productivity of the electrode plate will be improved.

In order to sufficiently suppress corrosion, the second fraction is preferably 40% or less, more preferably 30% or less, and even more preferably 17.5% or less. Note that even if the second partial ratio becomes even smaller than 50%, corrosion of the vertical bones cannot be completely suppressed. However, it is thought that if the corrosion is made uniform, uneven distribution of corroded parts will be suppressed, and elongation of the current collector in one direction will be suppressed.

The shape of the cross section C is not particularly limited, but is preferably octagonal. When the cross section C is octagonal, the internal angle of the apex does not become too small, and the effect of suppressing corrosion near the apex is enhanced. In order to form a vertical bone having an octagonal cross section C, for example, a vertical bone having a rectangular cross section C may be deformed. The method of deforming the vertical bone is not particularly limited, but for example, the inner bone may be press-worked. At that time, pressing conditions for the inner bone may be appropriately selected so that the second portion ratio is less than 50%, preferably 40% or less. Note that by making the shape of the cross section C into an octagon, it becomes easy to increase the ratio of the length of the first contour portion to the total length of the contour C. Here, the octagon does not have to be a strict octagon in the mathematical sense; the apex may be somewhat rounded, or each side may be slightly bent.

When the current collector is a punched lattice made of a stretched sheet of lead or lead alloy, the total length LW of the horizontal ribs and the total length WLH of the vertical ribs are WLH/WLW≧0. .8 may be satisfied, or WLH/WLW≧1.3 may be satisfied. In this case, since the corrosion of the current collector tends to progress inward, it is possible to suppress the elongation of the current collector by controlling the second fraction to less than 50%, and even less than 40%. becomes more noticeable. Here, the internal length of each internal bone means the length in the internal direction of a square of the lattice, that is, the length of a side (crosspiece length) of a rectangular space that defines the square. Note that the direction of the length WLW (the direction in which the transverse bones extend) usually corresponds to the stretching direction (MD direction) of the stretched sheet.

The current collector according to the present invention may be applied to either a positive electrode plate or a negative electrode plate. That is, the electrode plate according to the present invention can be either a positive electrode plate or a negative electrode plate. However, from the viewpoint of suppressing elongation due to corrosion of the current collector, the current collector according to the present invention is particularly suitable as a current collector for a positive electrode plate.

The current collector according to the present invention may be a punched current collector, and may be formed, for example, from a stretched sheet of lead or a lead alloy.

In the lead-acid battery according to one aspect of the present invention, positive electrode plates and negative electrode plates are alternately stacked with separators interposed in between to form an electrode group, and the electrode group is preferably pressurized in the stacking direction. . Specifically, when the electrode group is pressurized in the stacking direction, when the battery is disassembled and the electrode group is taken out, the electrode group is pressurized in the thickness direction of the central part of the cell chamber that accommodates the electrode group in the battery case. A state in which L2 is equal to L1 or a state in which L2 is longer than L1 (L2≧L1) in the length L1 (minimum distance between opposing inner wall surfaces) and the length L2 in the thickness direction of the central part of the electrode group. . Furthermore, when the electrode group is in the battery case, it refers to a state in which the electrode group is compressed in the thickness direction by applying pressure so that L2=L1. Pressure may be applied from the inner wall surface of the battery case, or may be applied from the outside using a press or the like. Thereby, the binding property between the current collector and the electrode material can be improved.

In the lead-acid battery according to one aspect of the present invention, the pull-out load of the electrode group may be 1.6 times or more, more preferably 2.0 times or more, and 2.3 times or more the own weight of the electrode group. More preferred. The pull-out load is the force that acts in the direction of pulling the electrode group out of the battery case when pulling out the electrode group of the lead-acid battery from the battery case. Specifically, it is considered that the binding between the current collector and the electrode material becomes good when the ratio of the load to the weight of the electrode group exceeds a predetermined value. A current collector in which the area of the exposed portion of the layered structure is large tends to have low binding properties with the electrode material. It is considered that the binding state (compression state) of the electrode group can be further enhanced by making the pull-out load of the electrode group including the positive electrode plate and the negative electrode plate at least 1.6 times the own weight of the electrode group. This makes it possible to improve the binding between the current collector and the electrode material.

The electrode group for measuring pull-out load and the electrode group for measuring dead weight both include a positive electrode plate, a negative electrode plate, a separator, and a strap. Note that when measuring the pull-out load, it is assumed that the battery case contains an electrolyte, and specifically, for example, the battery case is turned over, left for 5 minutes or more, and then the liquid is drained.

In the lead-acid battery according to one embodiment of the present invention, the positive electrode material preferably contains Sb (antimony). Sb can enhance the adhesion between the positive electrode current collector and the positive electrode material and ensure a conductive path between the positive electrode material and the current collector. When the electrode group is pressurized in the stacking direction, more conductive paths are ensured, and the effect of improving conductivity by Sb is significantly exhibited. By ensuring more conductive paths between the positive electrode material and the current collector, accumulation of lead sulfate is more easily suppressed, and softening of the positive electrode material is suppressed. Therefore, falling off of the positive electrode material is also easily suppressed.

The Sb content in the positive electrode material is the Sb content as an Sb element in the positive electrode material after chemical formation. It is also possible that Sb exists in the form of a compound (for example, an oxide or a sulfuric acid compound), but in that case as well, the Sb content is calculated by considering only the mass of Sb in the compound. The antimony content in the positive electrode material is preferably 0.01% by mass or more and 0.3% by mass or less. By controlling the Sb content within this range, gas generation can be suppressed and liquid loss can be minimized.

The Sb content in the positive electrode material can be determined by disassembling a fully charged lead-acid battery, washing the removed electrode plate with water, collecting the electrode material after drying, and dissolving the pulverized sample in concentrated nitric acid. (Inductively Coupled Plasma) It is determined by performing luminescence analysis.

Embodiments of the present invention will be described below with reference to the drawings.
FIGS. 1A and 1B are plan views showing the appearance of current collectors 100A and 100B according to one embodiment and another embodiment of the present invention, respectively. Current collectors 100A and 100B both have a frame rib 110 and a mesh-like inner rib 120 inside the frame rib 110. The frame 110 includes an upper element 111 continuous with the ear 130, a lower element 112 facing the upper element 111, and a pair of side elements 113 and 114 connecting the upper element 111 and the lower element 112. The dashed line indicates the boundary that trisects the inner bone into an upper region, a middle region, and a lower region. The current collector 100A in FIG. 1A has a lower protrusion (also referred to as a foot) 132 that is continuous with the lower element 112. In the current collector 100B of FIG. 1B, the transverse bones extend diagonally with respect to the upper element or the lower element. LH indicates the internal length per lattice of the vertical bone, and LW indicates the internal length per lattice of the horizontal bone.

The current collectors 100A and 100B are, for example, punched lattice bodies of stretched sheets of lead or lead alloy, and the stretching direction is the direction indicated by arrow MD in FIG. 1. A cross section C of the vertical bone 120A is a cross section along the line IIa-IIa in FIG. 1, and a cross section G of the horizontal bone 120B is a cross section along the line IIb-IIb. The metal structure of the stretched sheet tends to form a layered or fibrous structure extending in the stretching direction. Therefore, a striped pattern appears in the cross section C. On the other hand, in the cross section G, a pattern may occur due to cutting of a layered or fibrous structure.

FIG. 2A is an example of a photograph of a cross section C of the vertical bone 120A, and the cross section has an octagonal shape and a striped pattern of metal structure can be seen. FIG. 2B is a conceptual diagram of an example of an octagonal cross section C imitating FIG. 2A. On the other hand, FIG. 3 is an example of a photograph of a cross section G of the transverse bone 120B, in which a pattern due to a cross section perpendicular to the fiber length of the metal fibrous tissue can be seen. In FIG. 2B, most of the left and right sides of the octagonal cross section C are the second portion 220, and the other peripheral area is the first portion 210. In the first portion 210, the stripes of fibrous tissue (tangent line S2) have an angle θ1 with the contour of cross-section C (line S1) of less than 45°. On the other hand, in the second portion 220, either the stripes of the fibrous tissue cannot be confirmed, or the stripes (tangent line S2) have an angle θ2 of more than 45° with the outline of the cross section C (line S1). In addition, in FIG. 2A, there is a region in the outermost layer of the second portion 220 where a striped pattern of fibrous tissue with a thickness of less than about 55 μm is observed, but such a thin portion does not constitute the first portion 210. do not.

FIG. 4 is a conceptual diagram of cross section C showing the progress of corrosion of the inner bone. The portion where the shallow corrosion layer is formed is the first portion where the fibrous structure extends along the contour of the cross section C, and even if corrosion progresses, the corrosion layer is unlikely to be formed deep. On the other hand, peeling tends to occur near the interface between the current collector and the electrode material. Therefore, it is thought that the stress that causes the current collector to deform is likely to be relaxed. On the other hand, the portion where the wedge-shaped deep corrosion layer is formed is the second portion. When a deep corrosion layer is formed, the current collector tends to be deformed unevenly, the current collector stretches, and the electrode material tends to fall off.

Next, the electrode plate of the lead-acid battery will be explained. The electrode plate for a lead-acid battery according to the present invention includes the above current collector and an electrode material held by the current collector. The electrode material refers to parts other than the current collector, but if a mat mainly made of nonwoven fabric is attached to the electrode plate, the mat is not included in the electrode material. However, the thickness of the electrode plate shall include the matte. This is because the mat is used integrally with the electrode plate. However, if a mat is attached to the separator, the thickness of the mat is included in the thickness of the separator. The above current collector is suitable for application to a positive electrode plate, but may also be applied to a negative electrode plate.

The density of the electrode material may be, for example, 3.6 g/cm ³ or more. Further, from the viewpoint of ensuring sufficient initial capacity, the electrode material density is preferably 4.8 g/cm ³ or less. However, if the first portion ratio is less than 60% and the electrode material density increases to 4.4 g/cm ³ or more, cracks will easily occur in the electrode plate. Therefore, for example, when charging and discharging are repeated at a 5-hour rate current, deterioration may progress or charge acceptance after overcharging may decrease. On the other hand, when the first part ratio is 60% or more, even if the electrode material density is as high as 4.4 g/ ^cm3 or more, cracks do not easily occur in the electrode plate, resulting in deterioration during repeated discharges and charge acceptance after overcharging. Decrease in sexual ability is suppressed.

The density of the positive electrode material means the value of the bulk density of the fully charged positive electrode material, and is measured as follows. A battery that has just been chemically formed or used is fully charged and then disassembled, and the obtained positive electrode plate is washed with water and dried to remove the electrolyte in the positive electrode plate. (Water washing is performed by pressing a pH test paper against the surface of the washed electrode plate until it is confirmed that the color of the test paper does not change.However, the time for washing with water is within 2 hours.The washed positive electrode plate is washed with water. is dried at 60°C ± 5°C for about 6 hours. After drying, if the electrode plate contains an adhesive member, the adhesive member is removed from the electrode plate by peeling.)
Next, the positive electrode material is separated from the positive electrode plate to obtain an unpulverized measurement sample. After putting a sample into a measurement container and evacuating it, it is filled with mercury at a pressure of 0.5 psia or more and 0.55 psia or less (≈3.45 kPa or more and 3.79 kPa or less) to measure the bulk volume of the positive electrode material, The bulk density of the positive electrode material is determined by dividing the mass of the measurement sample by the bulk volume. Note that the volume obtained by subtracting the injection volume of mercury from the volume of the measurement container is defined as the bulk volume.

The density of the positive electrode material can be measured using an automatic porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation.

When charging and discharging cycles are repeated at a current rate of 5 hours, the electrode material repeatedly expands and contracts, making it easy for the interface between the current collector and the electrode material to physically separate. Assuming that the amount of electrode material is constant, as the density of the electrode material increases, its volume decreases and the amount of overpaste decreases. The overpaste refers to a portion of the electrode material that covers the outermost surface of the current collector in the thickness direction. Generally, when the amount of overpaste is small, the electrode plate is more likely to deteriorate, and it is considered that the discharge capacity decreases more due to repeated cycles. In this way, when the interface between the current collector and the electrode material is more likely to physically separate due to repeated charge/discharge cycles, the second portion ratio should be set to less than 50%, and t _b /t _a should be set to 60% or more. It is thought that the effect of controlling it to 97% or less will be significant. The effect of pressurizing the electrode group in the stacking direction and the securing of conductive paths by Sb are also significant.

Next, it is preferable that the maximum thickness T of the electrode material and the thickness t of the current collector satisfy T−t≦1 mm. (Tt)/2 corresponds to the thickness of the overpaste. The above current collector has excellent corrosion resistance and does not easily elongate due to corrosion, so the current collector is covered with a thick electrode material from the viewpoint of suppressing corrosion (or suppressing contact with the electrolyte). There's no need. Therefore, for example, even in a situation where the current collector is exposed from the electrode material and is about to come into direct contact with the electrolytic solution, the current collector is unlikely to deteriorate due to corrosion. Therefore, even if the electrode plate satisfies Tt≦1 mm, it can be used for a long period of time, and even if Tt<0 mm.

(Negative electrode plate)
The negative electrode plate of a lead-acid battery is composed of a negative electrode current collector and a negative electrode material. Negative current collectors for large lead-acid batteries may be formed by casting lead (Pb) or lead alloys.

As the lead or lead alloy used for the current collector, a Pb--Ca based alloy, a Pb--Ca--Sn based alloy, lead with a purity of three nines or higher, etc. are preferably used. These lead or lead alloys may further contain Ba, Ag, Al, Bi, As, Se, Cu, etc. as additional elements. The negative electrode current collector may have a plurality of lead alloy layers having different compositions.

The negative electrode material contains as an essential component a negative active material (lead or lead sulfate) that develops capacity through a redox reaction, and may also contain additives such as an organic antishrink agent, a carbonaceous material, and barium sulfate. The negative electrode active material in a charged state is spongy lead, but an unformed negative electrode plate is usually produced using lead powder.

As the organic anti-shrink agent, at least one selected from the group consisting of lignins and/or synthetic organic anti-shrink agents may be used. Examples of lignins include lignin and lignin derivatives. Examples of lignin derivatives include lignin sulfonic acid or its salts (alkali metal salts such as sodium salts, etc.). A synthetic organic antishrink agent is an organic polymer containing elemental sulfur, and generally contains a plurality of aromatic rings in the molecule and elemental sulfur as a sulfur-containing group. Among the sulfur-containing groups, stable forms of sulfonic acid or sulfonyl groups are preferred. The sulfonic acid group may exist in an acid form or in a salt form such as Na salt.

As a specific example of the organic anti-shrink agent, a condensate of an aldehyde compound (aldehyde or a condensate thereof, such as formaldehyde) of a compound having a sulfur-containing group and an aromatic ring is preferable. Examples of the aromatic ring include a benzene ring and a naphthalene ring. When the compound having an aromatic ring has a plurality of aromatic rings, the plurality of aromatic rings may be connected by a direct bond or a connecting group (for example, an alkylene group, a sulfone group, etc.). Examples of such structures include biphenyl, bisphenylalkane, bisphenyl sulfone, and the like. Examples of the compound having an aromatic ring include compounds having the above-mentioned aromatic ring and a hydroxy group and/or an amino group. The hydroxy group or amino group may be bonded directly to the aromatic ring, or may be bonded as an alkyl chain having a hydroxy group or amino group. Preferred examples of the compound having an aromatic ring include bisphenol compounds, hydroxybiphenyl compounds, hydroxynaphthalene compounds, and phenol compounds. The compound having an aromatic ring may further have a substituent. The organic anti-shrink agent may contain one kind of residues of these compounds or may contain two or more kinds of residues. Preferred bisphenol compounds include bisphenol A, bisphenol S, and bisphenol F.

The sulfur-containing group may be directly bonded to the aromatic ring contained in the compound, or may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group, for example.

Furthermore, for example, a condensate of the above-mentioned aromatic ring-containing compound and a monocyclic aromatic compound (aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, phenolsulfonic acid or a substitute thereof, etc.) with an aldehyde compound. , may be used as an organic antishrink agent.

The content of the organic antishrink agent contained in the negative electrode material is, for example, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more. On the other hand, it is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less. These lower limit values and upper limit values can be arbitrarily combined. Here, the content of the organic antishrink agent contained in the negative electrode material is the content in the negative electrode material collected from a fully charged lead-acid battery in a chemically formed manner by the method described below.

As the carbonaceous material contained in the negative electrode material, carbon black, graphite, hard carbon, soft carbon, etc. can be used. Examples of carbon black include acetylene black, furnace black, and lamp black. Furnace black also includes Ketjen black (product name). Graphite may be any carbon material including a graphite-type crystal structure, and may be either artificial graphite or natural graphite.

The content of the carbonaceous material in the negative electrode material is, for example, preferably 0.05% by mass or more, and more preferably 0.2% by mass or more. On the other hand, it is preferably 4.0% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

The content of barium sulfate in the negative electrode material is, for example, preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.3% by mass or more. On the other hand, it is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

Below, a method for quantifying the organic shrink-proofing agent, carbonaceous material, and barium sulfate contained in the negative electrode material will be described. Prior to quantitative analysis, the chemically formed lead-acid battery is fully charged and then disassembled to obtain the negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water and dried to remove the electrolyte in the negative electrode plate. (Water washing is carried out until it is confirmed that the pH test paper is pressed against the surface of the washed negative electrode plate and the color of the test paper does not change.However, the time for washing with water is within 2 hours.The washed negative electrode plate is washed with water. is dried at 60°C ± 5°C in a reduced pressure environment for about 6 hours. After drying, if the negative electrode plate contains an adhesive member, the adhesive member is removed from the negative electrode plate by peeling.) Next, the negative electrode An unpulverized sample S is obtained by separating the negative electrode material from the plate.

[Organic anti-shrink agent]
The unground sample S is ground, and the ground sample S is immersed in a 1 mol/L NaOH aqueous solution to extract the organic shrink-proofing agent. Insoluble components are removed by filtration from the NaOH aqueous solution containing the extracted organic anti-shrink agent. The obtained filtrate (hereinafter also referred to as the analyte filtrate) is desalted, concentrated, and dried to obtain an organic shrink-proofing agent powder (hereinafter also referred to as the analyte powder). Desalination may be performed by placing the filtrate in a dialysis tube and immersing it in distilled water.

Infrared spectrum of the powder to be analyzed, UV-visible absorption spectrum of the solution obtained by dissolving the powder to be analyzed in distilled water, etc., NMR spectrum of the solution obtained by dissolving the powder to be analyzed in a solvent such as heavy water, The organic antishrink agent is identified by obtaining information from pyrolysis GC-MS, etc., which can obtain information on the individual compounds that make up the product.

The ultraviolet-visible absorption spectrum of the filtrate to be analyzed is measured. The content of the organic antishrink agent in the negative electrode material is quantified using the spectral intensity and a calibration curve prepared in advance. If the structural formula of the organic anti-shrink agent to be analyzed cannot be precisely specified and a calibration curve of the same organic anti-shrink agent cannot be used, use a UV-visible absorption spectrum, an infrared spectroscopic spectrum, or a similar one to the organic anti-shrink agent to be analyzed. A calibration curve is prepared using available organic anti-shrink agents showing NMR spectra, etc.

[Carbonaceous materials and barium sulfate]
The unpulverized sample S is ground, and 50 ml of nitric acid with a concentration of 20% by mass is added to 10 g of the ground sample S and heated for about 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate is filtered to remove solids such as carbonaceous materials and barium sulfate.

After the obtained solid content is dispersed in water to form a dispersion liquid, components other than the carbonaceous material and barium sulfate (for example, reinforcing material) are removed from the dispersion liquid using a sieve. Next, the dispersion liquid is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter and the filtered sample are dried in a dryer at 110° C.±5° C. The filtered sample is a mixed sample of carbonaceous material and barium sulfate. The mass (A) of the mixed sample is measured by subtracting the mass of the membrane filter from the total mass of the dried mixed sample and membrane filter. Thereafter, the dried mixed sample is placed in a crucible together with a membrane filter, and ignited at 700° C. or higher. The remaining residue is barium oxide. The mass of barium sulfate (B) is determined by converting the mass of barium oxide to the mass of barium sulfate. The mass of the carbonaceous material is calculated by subtracting the mass B from the mass A.

The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying it to produce an unformed negative electrode plate, and then chemically converting the unformed negative electrode plate. The negative electrode paste is made by adding water and sulfuric acid to lead powder and various additives, and then kneading the mixture. In the aging step, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and high humidity.

Forming can be performed by charging the electrode group including an unformed negative electrode plate while immersing the electrode group in an electrolytic solution containing sulfuric acid in a container of a lead-acid battery. However, chemical formation may be performed before assembly of the lead-acid battery or the electrode group. Through chemical formation, spongy lead is formed.

(positive electrode plate)
A positive electrode plate of a lead-acid battery includes a positive current collector and a positive electrode material. The positive electrode current collector may be formed in the same manner as the negative electrode current collector, and the positive electrode current collector for large lead-acid batteries may be formed by casting lead or a lead alloy.

The lead or lead alloy used for the positive electrode current collector is preferably a Pb-Ca alloy or a Pb-Ca-Sn alloy from the viewpoint of corrosion resistance and mechanical strength, and pure lead with a purity of three nines or more (99.9% ) may be used. The positive electrode current collector may have lead alloy layers having different compositions, and may have a plurality of alloy layers.

The positive electrode material includes a positive active material (lead dioxide or lead sulfate) that develops capacity through a redox reaction. The positive electrode material may contain additives, if necessary.

An unformed positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging and drying the paste. Thereafter, the unformed positive electrode plate is chemically formed. The positive electrode paste is prepared by kneading lead powder, additives, water, sulfuric acid, and the like.

(electrolyte)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may be gelled if necessary. The specific gravity of the electrolyte at 20° C. in a fully charged lead-acid battery is, for example, 1.20 to 1.35, preferably 1.25 to 1.32.

(Separator)
A separator is usually placed between the negative electrode plate and the positive electrode plate. Nonwoven fabric, microporous membrane, etc. are used for the separator. Nonwoven fabric is a mat made of fibers intertwined without being woven, and is mainly composed of fibers. For example, 60% by mass or more of the nonwoven fabric is made of fibers. As the fiber, glass fiber, polymer fiber, pulp fiber, etc. can be used. The nonwoven fabric may contain components other than fibers, such as acid-resistant inorganic powder and a polymer as a binder. A microporous membrane is a porous sheet whose main component is other than fiber components. For example, a composition containing a pore-forming agent (polymer powder, oil, etc.) is extruded into a sheet shape, and then the pore-forming agent is removed. It is obtained by forming pores. The microporous membrane is preferably composed mainly of a polymer component. As the polymer component, polyolefins such as polyethylene and polypropylene are preferred.

FIG. 5 shows a perspective view of the appearance of a lead-acid battery according to an embodiment of the present invention. The lead-acid battery 1 includes a container 12 that houses an electrode group 11 and an electrolyte (not shown). The inside of the battery case 12 is partitioned into a plurality of cell chambers 14 by a partition wall 13. Each cell chamber 14 accommodates one electrode group 11. The opening of the battery case 12 is closed with a lid 15 having a negative terminal 16 and a positive terminal 17. The lid 15 is provided with a liquid port plug 18 for each cell chamber. When refilling water, the liquid port stopper 18 is removed and the rehydration liquid is replenished. The liquid port plug 18 may have a function of discharging gas generated within the cell chamber 14 to the outside of the battery.

The electrode group 11 is constructed by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 with a separator 4 in between. Although a bag-shaped separator 4 that accommodates the negative electrode plate 2 is shown here, the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects the ears 2a of the plurality of negative electrode plates 2 in parallel is connected to the through-connection body 8, and connects the ears 3a of the plurality of positive electrode plates 3 in parallel. Positive electrode shelf portions 5 connected in parallel are connected to positive electrode column 7 . The positive electrode column 7 is connected to a positive electrode terminal 17 outside the lid 15. In the cell chamber 14 located at the other end of the battery case 12 , the negative pole 9 is connected to the negative shelf 6 , and the through connector 8 is connected to the positive shelf 5 . The negative electrode column 9 is connected to a negative electrode terminal 16 outside the lid 15. Each through-connection body 8 passes through a through-hole provided in the partition wall 13 and connects the electrode groups 11 of adjacent cell chambers 14 in series.

Although FIG. 5 shows an example of a liquid type battery (vented type battery), the lead acid battery may be a valve regulated type battery (VRLA type).

Next, performance evaluation of lead-acid batteries will be explained.
[Evaluation of test battery]
(a) 5-hour rate discharge capacity test Using a test battery, conduct in a water tank at 25°C ± 2°C as follows. Discharge to 1.75V/cell at a constant current (current (A) that is 0.2 times the value stated as the 5-hour rate rated capacity (Ah)), then discharge at a constant current (as the 5-hour rate rated capacity (Ah)). Charge the battery to 135% of the discharge amount using a current (A) that is 0.2 times the stated value. The same cycle is repeated 5 times, and the 5-hour rate discharge capacity of the 5th cycle is determined.
Note that the numerical value described as the rated capacity is a numerical value in Ah. The unit of current set based on the numerical value stated as the rated capacity is A.

(b) Single plate overcharge test Use a test battery. An overcharge test was conducted in a water tank at 75°C ± 2°C using a constant current (5-hour rate rated capacity (Ah) with a current (A) equal to 0.2 times the value obtained by dividing the number of positive electrode plates per cell). Repeat this operation for 5 days, then rest for 2 days (1 week) for 5 weeks.The numerical value described as the rated capacity is a numerical value in Ah.It is set based on the numerical value described as the rated capacity. The unit of current is A.
For example, in the case of a battery with a 5-hour rate rated capacity of 30Ah and 12V, which is composed of 6 positive plates and 7 negative plates, the rated capacity of a single cell (1 positive plate, 2 negative plates) is 30÷ 6=5Ah, and the current value in the single-board overcharge test is 5×0.2=1A. The period until the vertical elongation of the positive electrode current collector reaches 7% of the initial ratio in the single plate overcharge test is determined. If the period is 3.5 weeks or less, it is determined that there is a high possibility of an elongation short circuit. The longitudinal elongation is determined by measuring the dimension of the part of the frame of the positive electrode current collector that bulges out the most in the first direction (height direction) and comparing it with the initial dimension.

(c) Electrode group compression test After fully charging and disassembling the battery that has just been chemically formed or used, the electrode group is pulled out from the battery case using a load measuring device (a spring-type hand balance manufactured by Sanko Seikosho Co., Ltd.). Measure the pull-out load at this time. Note that when measuring the pull-out load, it is assumed that the electrolyte is contained, and specifically, for example, the battery case is turned over, left for 5 minutes or more, and then the liquid is drained.

The lead-acid battery according to the present invention will be summarized below.
(1) A lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the positive electrode plate and the negative electrode plate each include a current collector and an electrode material held on the current collector. and, the current collector has a frame bone, an ear provided on the frame bone, and an inner bone inside the frame bone, and the frame bone has an upper portion continuous with the ear. an element, a lower element facing the upper element, and a pair of side elements connecting the upper element and the lower element, the inner bone having a first section extending from the upper element toward the lower element. comprising a vertical bone extending in one direction and a horizontal bone extending in a second direction from one side element to the other side element, in a cross section of the vertical bone perpendicular to the first direction, A striped pattern of a metal fibrous structure is seen, and the outer peripheral region of the cross section is composed of a first portion in which the fibrous structure extends along the contour of the cross section, and a second portion other than the first portion. The ratio of the length of the contour corresponding to the second portion to the total length of the cross-sectional contour is less than 50%, and the ratio t of the inner bone thickness t _b to the ear thickness t _a A lead-acid battery whose _b /t _a is 60% or more and 97% or less.

(2) The lead-acid battery according to (1) above, wherein the ratio of the length of the contour corresponding to the second portion to the total length of the contour of the cross section is 40% or less.

(3) The lead-acid battery according to (1) above, wherein the ratio of the length of the contour corresponding to the second portion to the total length of the contour of the cross section is 30% or less.

(4) In any one of (1) to (3) above, the positive electrode plate and the negative electrode plate are alternately laminated with separators interposed therebetween to form an electrode group, and the electrode group is applied in the lamination direction. A lead-acid battery under pressure.

(5) The lead-acid battery according to any one of (1) to (3) above, wherein the pull-out load of the electrode group including the positive electrode plate and the negative electrode plate is 1.6 times or more the own weight of the electrode group.

(6) The lead-acid battery according to any one of (1) to (3) above, wherein the pull-out load of the electrode group including the positive electrode plate and the negative electrode plate is 2.0 times or more the own weight of the electrode group.

(7) The lead-acid battery according to any one of (1) to (3) above, wherein the pull-out load of the electrode group including the positive electrode plate and the negative electrode plate is 2.3 times or more the own weight of the electrode group.

(8) The lead-acid battery according to any one of (1) to (7) above, wherein the current collector or positive electrode material contains Sb.

(9) A method for manufacturing a lead-acid battery according to any one of (1) to (8) above, including the steps of preparing the current collector and obtaining the positive electrode plate or the negative electrode plate containing the current collector. and an intermediate having a plurality of intermediate ribs formed in a lattice shape by preparing the current collector by preparing a rolled plate and punching the rolled plate. The method includes a step of forming a lattice body, and a step of press working the intermediate lattice body from the thickness direction of the intermediate lattice body to form at least a part of the inner bone, and the pressing process includes: In at least a portion of the plurality of intermediate bones, at least one end portion in the bone width direction is thinner than the center portion in the bone width direction intersecting the extending direction of the intermediate bones, and the ear thickness _{t a} A method for manufacturing a lead-acid battery, comprising deforming the central portion so that a ratio t _b /t _a of the thickness t _b of the central portion to the thickness t b is 60% or more and 97% or less.

Hereinafter, embodiments of the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(1) Preparation of current collector A rolled sheet of Pb-Ca-Sn alloy is punched out, and the inner rib is pressed so that the second portion ratio of cross section C is 40% and the thickness of the ear is t _a . A current collector A1 is obtained in which the ratio t _b /t _a of the inner bone thickness t _b is 80%.

The specifications of the current collector A1 are as follows.
Inner bone thickness: 0.95mm
Frame height H: 115mm
Frame width W: 137mm
Second part ratio of section C: 40% (first part ratio: 60%)
Ratio of inner bone thickness to ear thickness (t _b /t _a ): 80%

(2) Preparation of positive electrode plate A positive electrode paste containing lead powder was prepared, a current collector was filled with the positive electrode paste, and the paste was aged and dried to produce an unformed positive electrode plate. The density of the positive electrode material after chemical formation is adjusted to 3.6 g/cm ³ .

(3) Preparation of Negative Electrode Plate A negative electrode paste is prepared by mixing lead powder, water, dilute sulfuric acid, barium sulfate, carbon black, and 0.2% by mass of lignin as an organic anti-shrink agent. The grid body A1 is filled with a negative electrode paste, aged and dried to obtain an unformed negative electrode plate.

(4) Preparation of test batteries In each of the following test batteries, a sulfuric acid aqueous solution is used as the electrolyte. The specific gravity of the electrolytic solution used in test battery X at 20° C. is 1.28. In test battery Y, after chemical formation, the specific gravity of the electrolyte at 20° C. is adjusted to 1.28 in each fully charged test battery.

(a) Preparation of test battery X Test battery X is assembled using a positive electrode current collector carrying a positive electrode material. The test battery is a 2V cell. Test battery X consists of one positive electrode current collector and two negative electrode plates sandwiching it. The negative electrode plate is housed in a bag-like separator.

(b) Preparation of test battery Y Test battery Y is assembled using a positive electrode plate in which a positive electrode material is supported on a positive electrode current collector. An unformed negative electrode plate is housed in a bag-like separator, and an electrode group is formed by six unformed positive electrode plates and seven unformed negative electrode plates. The electrode group is housed together with an electrolyte in a polypropylene container, and chemical conversion is performed in the container to produce a test battery Y (12 V, 5 hour rate rated capacity 30 Ah).

<5 hour rate discharge capacity test>
A test battery Y1 is produced using the above positive electrode plate and negative electrode plate.

Various test batteries were prepared in the same manner as above, except that the t _b /t _a ratio and the second fraction of the cross section C were changed as shown in Table 1. Note that when the t _b /t _a ratio is 100%, the current collector is not processed by pressure.

Table 1 shows the results of the 5-hour rate discharge capacity test for batteries Y1 to Y8 and YR1 to YR16. Note that the ratio of the 5-hour rate discharge capacity is expressed as a ratio when the 5-hour rate discharge capacity of the battery without processing of the current collector (t _b / _ta = 100%) is taken as 100.

FIG. 6 shows the relationship between t _b /t _a and the 5-hour rate discharge capacity. From FIG. 6, it can be seen that the smaller the ratio t _b / _{t a of} the inner bone thickness t _b to the ear thickness t a, the greater the 5-hour rate discharge capacity. This is considered to be due to improved binding between the current collector and the electrode material. The smaller the second partial ratio is, the more remarkable the increase in the 5-hour rate discharge capacity is.

<Single board overcharge test>
Table 2 shows the results of the single-plate overcharge test for batteries X4, X5, XR4, and XR13, which were manufactured using the same positive electrode current collectors as batteries Y4, Y5, YR4, and YR13. Note that the overcharge period in the single plate overcharge test indicates the period until the vertical elongation of the positive electrode current collector reaches 7% of the initial ratio.

FIG. 7 shows the relationship between t _b /t _a and the overcharge period in the single-board overcharge test. From FIG. 7, if the ratio of the inner bone thickness to the ear thickness of the current collector is 60% or more, the period until the vertical elongation of the positive electrode current collector reaches 7% of the initial ratio is 3.5%. I know it will last more than a week.

<Electrode group compression test>
Batteries PY4, PYR3, PYR13, and PYR14 were fabricated in the same manner as batteries Y4, YR3, YR13, and YR14, except that the electrode groups were pressurized in the stacking direction, and the influence of the presence or absence of pressure on the electrode groups on the 5-hour rate discharge capacity was investigated. investigate. The results are shown in Table 3. The ratio of the 5-hour rate discharge capacity in Table 3 is the ratio of the 5-hour rate discharge capacity when pressure is applied to the 5-hour rate discharge capacity when no pressure is applied to the electrode group. Note that the pull-out load of the electrode group is 2.3 times the weight of the electrode group itself.

FIG. 8 is a bar graph showing the ratio of the 5-hour rate discharge capacity when pressure is applied to the 5-hour rate discharge capacity when no pressure is applied to the electrode group. From FIG. 8, when the ratio of the outer circumference of the second portion is 17% and the ratio of the thickness of the inner bone to the thickness of the ear of the current collector is 80%, the gap between the current collector and the positive electrode material due to compression It can be seen that the effect of improving binding properties becomes remarkable.

Next, battery P12Y4 was processed in the same manner as battery Y4, except that the electrode group was pressurized in the stacking direction so that the pull-out load was 1.2 times, 1.6 times, 2 times, and 2.3 times the electrode group's own weight. , P16Y4, P20Y4, and P23Y4 were produced, and the influence of the difference in pull-out load on the 5-hour rate discharge capacity was investigated. The results are shown in Table 4. The ratio of the 5-hour rate discharge capacity in Table 4 is 1.2 times the pull-out load, 1.6 times the 5-hour rate discharge capacity when the pull-out load is 1.1 times the weight of the electrode group (Battery Y4), This is the ratio of the 5-hour rate discharge capacity in the case of 2 times and 2.3 times. Note that when there is no pressure on the electrode group, the pull-out load is 1.1 times the weight of the electrode group itself.

FIG. 9 is a bar graph showing the ratio of the 5-hour rate discharge capacity according to the pull-out load of the electrode group. From FIG. 9, it can be seen that the 5-hour rate discharge capacity is significantly improved by making the pull-out load of the electrode group 1.6 times or more the own weight of the electrode group.

<Influence of antimony>
Next, batteries SY4, SYR3, SYR13 and SYR14 were produced, and the influence of whether or not Sb ₂ O ₃ was added to the positive electrode material on the 5-hour rate discharge capacity was investigated. The results are shown in Table 5. The ratio of the 5-hour rate discharge capacity in Table 5 is the ratio of _the 5-hour rate discharge capacity when Sb 2 O 3 is added to the 5 _{-hour rate discharge capacity when Sb 2 O 3} is not added to the positive electrode material.

FIG. 10 is a bar graph showing the ratio of the 5-hour rate discharge capacity when Sb ₂ O ₃ is added to the 5-hour rate discharge capacity when Sb ₂ O ₃ is not added to the positive electrode material. From FIG. 10, when the ratio of the outer circumference of the second part is 17% and the ratio of the inner bone thickness to the ear thickness of the current collector is 80%, the current collector and positive electrode with Sb ₂ O ₃ added It can be seen that the effect of improving the binding property between electrode materials becomes remarkable.

The current collector for lead-acid batteries according to the present invention is applicable to valve-controlled and liquid-type lead-acid batteries, and can be used as a starting power source for automobiles, motorcycles, etc., and industrial power storage devices such as electric vehicles (forklifts, etc.). It can be suitably used as a power source.

1: Lead-acid battery, 2: Negative electrode plate, 3: Positive electrode plate, 4: Separator, 5: Positive electrode shelf, 6: Negative electrode shelf, 7: Positive electrode column, 8: Through-connection body, 9: Negative electrode column, 11: Electrode Group, 12: Battery case, 13: Partition wall, 14: Cell chamber, 15: Lid, 16: Negative electrode terminal, 17: Positive electrode terminal, 18: Liquid port plug, 100: Current collector, 110: Frame bone, 111: Upper part Element, 112: Lower element, 113, 114 Side element, 120: Internal bone, 120A: Vertical bone, 120B: Transverse bone, 130: Ear, 132: Lower process, 210: First part, 220: Second part

Claims (5)

A lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte,
The positive electrode plate and the negative electrode plate each include a current collector and an electrode material held by the current collector,
The current collector has a rectangular frame bone, an ear provided on the frame bone, and an inner bone inside the frame bone,
The frame bone includes an upper element continuous with the ear, a lower element facing the upper element, and a pair of side elements connecting the upper element and the lower element,
The inner bone includes a vertical bone extending in a first direction from the upper element to the lower element, and a horizontal bone extending in a second direction from one of the side elements to the other side element. ,
In a cross section of the longitudinal bone perpendicular to the first direction, a striped pattern of metal fibrous tissue is seen;
The outer peripheral region of the cross section is composed of a first portion in which the fibrous tissue extends along the contour of the cross section, and a second portion other than the first portion,
The proportion of the length of the contour corresponding to the second portion to the total length of the contour of the cross section is less than 50%,
A lead-acid battery, wherein a ratio t _b /t _a of the thickness t _b of the inner bone to the thickness t _a of the ear is 60% or more and 97% or less. The positive electrode plate and the negative electrode plate are alternately stacked with separators interposed therebetween to form an electrode group,
The lead-acid battery according to claim 1, wherein the electrode group is pressurized in a stacking direction. The pull-out load of the electrode group is 1.6 times or more the own weight of the electrode group,
Lead-acid battery according to claim 1 or 2 The lead-acid battery according to any one of claims 1 to 3, wherein the positive electrode material contains Sb. A method for manufacturing a lead-acid battery according to any one of claims 1 to 4, comprising:
a step of preparing a current collector;
obtaining the positive electrode plate or the negative electrode plate including the current collector,
The step of preparing the current collector includes:
a step of preparing a rolled plate;
forming an intermediate lattice body having a plurality of intermediate ribs formed in a lattice shape by punching the rolled plate;
Pressing the intermediate lattice body from the thickness direction of the intermediate lattice body to form at least a part of the inner bone,
The press working is performed such that at least one end portion in the bone width direction is thinner in at least a portion of the plurality of intermediate bones than the center portion in the bone width direction intersecting the extending direction of the intermediate bones, and the ear thickness t _a The thickness t of the central portion with respect to _b The proportion t _b /t _a A method for manufacturing a lead-acid battery, the method comprising deforming the battery so that the ratio is 60% or more and 97% or less.

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