WO2012172754A1

WO2012172754A1 - Pole plate for lead storage battery, lead storage battery, and method for producing pole plate for lead storage battery

Info

Publication number: WO2012172754A1
Application number: PCT/JP2012/003709
Authority: WO
Inventors: 晃平佐野; 明俊平松; 岡本　浩
Original assignee: パナソニック株式会社
Priority date: 2011-06-17
Filing date: 2012-06-06
Publication date: 2012-12-20
Also published as: CN103348512A; JP5903606B2; CN103348512B; JPWO2012172754A1

Abstract

This pole plate for a lead storage battery comprises an expandable grid formed from lead or a lead alloy and an active substance packed in the expandable grid. The expandable grid is a quadrangle having a tab part projecting from one side. When the expandable grid stands vertically such that the side having the tab part is the top side, the upward facing surface and the downward facing surface of the grid strands have a surface compact layer that has a smaller crystal grain diameter than the center portion of the strands and the compact layer of the upward facing surface of the strands is thinner than that of the downward facing surface.

Description

Lead plate for lead storage battery, lead storage battery, and method for manufacturing lead plate for lead storage battery

The present invention relates to an electrode plate for a lead storage battery using an expanded lattice, a lead storage battery using the electrode plate, and a method for manufacturing the electrode plate for a lead storage battery.

The electrode plate for a lead storage battery is manufactured by filling a lattice made of lead and a lead alloy with an active material paste containing lead and a lead compound and drying. This lattice is mainly produced by one of the following two methods. The first is a casting method (including a continuous casting method) in which a molten metal made of lead and lead alloy is poured into a lattice-shaped mold. The second is an expanding method in which a strip-like slab obtained by continuously cooling a molten metal composed of lead and a lead alloy is rolled to produce a sheet, and a staggered slit is formed on the sheet to extend the sheet. . Of these two methods, the expanding method with excellent productivity has been increasingly adopted.

この This expanding method is largely divided into two depending on the movement of the blade. The reciprocating method is a method in which a slit is formed in the sheet by reciprocating a die blade corresponding to the slit to be formed, and the slit portion is extended to form an expanded mesh. On the other hand, the rotary method is a method in which a slit is formed in a sheet with a rotating disk-shaped cutter to form an expanded mesh. Of these two methods, a grid obtained by a reciprocating method, which is inferior in productivity but is not corroded at the intersection of the expanded mesh and is not easily corroded, is often used for the positive electrode plate.

By the way, the grid obtained by the casting method and the slab used for the expanding method have different metal structures, and thus have different advantages.

The lattice continuum obtained by the continuous casting method has a metal structure with a large crystal grain size. When the crystal grain size is large, there is an advantage that the absolute amount of corrosion is reduced because the crystal grain boundary is reduced, and the change in strength at high temperature is reduced.

On the other hand, the slab obtained by continuously cooling the molten metal has a metal structure having a smaller crystal grain size as compared with the above-described method. If the crystal grain size is small, the strength is increased, so that it is suitable for the expanding process, and moreover, the crystal grain boundary increases, so that there is an advantage that corrosion does not easily progress inside. On the other hand, as the number of grain boundaries increases, the absolute amount of corrosion increases. In particular, when charging and discharging are repeated at high temperatures, the lattice easily expands and protrudes from the top of the separator, causing a short circuit and shortening the life. There is a drawback.

Patent Documents

1 and 2 describe a technology that combines the advantages of both methods. Specifically, a layer with a small crystal grain size (dense layer) is provided on the surface of a sheet obtained by rolling a slab, and the crystal grain size at the center is larger than that of the dense layer, thereby providing corrosion resistance and expanding processing. Describes a technique for achieving both strengths suitable for the above. The techniques described in

Patent Documents

1 and 2 skillfully utilize the actual state of slab casting, in which a molten layer is cooled from the surface, so that a dense layer is easily formed on the surface.

JP 2005-056622 A JP 2004-031041 A

However, when a dense layer is randomly provided on the surface of the slab, when the expanded lattice is produced by processing the slab, a lattice bone (strand) constituting the expanded mesh is broken. Even if the lattice bone is not broken, when a lead-acid battery is constructed using an electrode plate made of this expanded lattice, not only the cycle life characteristics deteriorate, but also the positive electrode lattice extends and short-circuits (suddenly). It has been found that the problem is not fully resolved. If the battery is short-circuited and suddenly died, the lead-acid battery suddenly loses its function from the state where the battery is fully functioning, and charging / discharging cannot be performed. For example, when a lead storage battery for an automobile cell starter suddenly dies, the user (car driver) cannot predict the lead life of the lead storage battery, so maintenance such as replacing the lead storage battery in advance during inspections such as vehicle inspections cannot be performed. .

The present invention has been made with respect to the above-mentioned problems, and has a high expandability and cycle life characteristics, and a lead plate for a lead storage battery in which short-circuiting due to elongation of the grid of the positive plate is suppressed, and the production of the lead plate for the lead storage battery A method is provided.

In order to solve the above problems, an electrode plate for a lead storage battery according to the present invention includes an expanded lattice made of lead or a lead alloy, and an active material filled in the expanded lattice, and the expanded lattice has a quadrilateral shape. And has a tab portion protruding from one side, and when the expanded lattice is set up vertically with the side having the tab portion as an upper side, the surface of the lattice strand faces upward and downward. The surface has a dense layer having a crystal grain size smaller than the central part of the strand on the surface, and the dense layer is thinner on the surface facing upward of the strand than on the surface facing downward. is doing.

The thickness A of the dense layer on the surface facing upward of the strand and the thickness B of the dense layer on the surface facing downward have a relationship that A / B is 0.14 or more and 0.50 or less. It may be.

Thickness between the dense layer thickness A of the surface facing the strand, the thickness B of the dense layer of the surface facing downward, and the thickness between the surface facing upward and the surface facing downward of the strand C may have a relationship in which (A + B) / C is 0.15 or more and 0.40 or less.

The lead alloy may contain antimony. It is preferable that 2% by mass or less of antimony is contained in the lead alloy.

The lead storage battery of the present invention has a configuration in which the above-described electrode plate for lead storage battery is used as at least one of a positive electrode plate and a negative electrode plate and is opposed to a counter electrode plate via a separator.

The method for producing an electrode plate for a lead storage battery according to the present invention includes a first step of continuously cooling a molten metal made of lead or a lead alloy to cast a strip slab, and rolling the slab to produce a strip sheet. A strip-like expanded lattice is produced by a second step of reciprocating and developing in a direction perpendicular to the longitudinal direction of the sheet while forming a plurality of staggered cuts parallel to the longitudinal direction of the sheet A third step, and a fourth step of filling an active material paste containing lead and a lead compound into the expanded lattice and drying, then cutting to a predetermined size to produce an electrode plate, and In the step, dense layers having a crystal grain size smaller than that of the central portion are provided on both surfaces of the slab with different thicknesses on both surfaces, and in the third step, the dense layer is formed from a thin surface from the surface of the slab. Put the cut It has a configuration which forms the eyes.

The ratio A / B between the thickness A of the thinner dense layer and the thickness B of the other layer in the third step may be 0.14 or more and 0.50 or less.

The ratio (A + B) / C between the thickness C of the sheet in the third step and the sum A + B of the thickness A of the thinner dense layer and the thickness B of the other layer is 0.15 or more and 0.40 or less. There may be.

In the present invention, the lead alloy is an alloy containing more than 50% by weight of lead. The strand is a bar-shaped member having a square cross section surrounding the expanded lattice. That is, the strand forms a lattice.

A dense layer is a layer that is relatively densely observed compared to other parts when observed with a microscope because the size of the crystal grains constituting the layer is small compared to other parts. . In this invention, the crystal grain in the predetermined thickness range of the sheet | seat surface points out that it is smaller than the crystal grain of the center part of the thickness direction of a sheet | seat.

An antimony contained in the lead alloy of 2% by weight or less means that the antimony is contained in the lead alloy but the upper limit of the content is 2% by weight.

The reciprocating method is a method in which a blade is reciprocated up and down on a horizontally placed lead sheet to form a cut.

According to the present invention, the expandability of the lead storage battery electrode plate is enhanced. Furthermore, the lead acid battery using this electrode plate has a high cycle life characteristic, and has a remarkable effect that the short circuit accompanying the expansion of the grid of the positive electrode plate is suppressed.

It is the schematic which shows a part of manufacturing method of the electrode plate for lead acid batteries which concerns on embodiment. It is the schematic which shows another part of the manufacturing method of the electrode plate for lead acid batteries which concerns on embodiment. It is the schematic which shows another part of the manufacturing method of the electrode plate for lead acid batteries which concerns on embodiment. It is the schematic which shows the principal part of the manufacturing method of the electrode plate for lead acid batteries which concerns on embodiment. It is an external view which shows the lead acid battery which concerns on embodiment. It is a figure which shows the expanded grating | lattice which concerns on embodiment. It is a drawing substitute photograph which shows a part of cross section of a strand.

First, the background that led to the present invention will be described.

After rolling a lead or lead alloy slab to form a sheet, when the sheet is expanded by a reciprocating method, the sheet is pushed down from the surface on the side where the die blade is inserted by the die blade. For this reason, it is considered that the opposite surface of the sheet has a relatively high stretch rate, and the stress applied during processing increases in accordance with the stretch rate. The present inventors paid attention to this point, and for the first time discovered the mechanism of the problem shown below, and reached the present invention.

When casting a slab by continuously cooling a molten metal made of lead or a lead alloy, the molten metal is cooled from the surface, so that a dense layer is easily formed on the surface. That is, since the surface of the molten metal is cooled quickly, the crystal grain size becomes small, and the inside (center portion) of the molten metal is cooled slowly, so that the crystal grain size becomes large. If both surfaces of the molten metal are cooled substantially uniformly, the dense layers formed on both surfaces have substantially the same thickness. As described above, this dense layer is not only suitable for expanding processing because of its small crystal grain size, but also because of its large number of crystal grain boundaries, corrosion hardly progresses toward the inside.

However, when expanding, the side where the die blade is inserted has a relatively low extension rate, so the structure of the dense layer is the same as before, but the other side pressed down is considered to have a relatively high extension rate. Therefore, it has been found that the dense layer is spread and easily broken. When the degree of breakage is large, the expand processability itself deteriorates, so that a problem in the manufacturing process that the strand is cut due to the occurrence of a crack occurs. Further, since the dense layer is broken even if the strand is not cut, the central portion in the thickness direction of the sheet having a large crystal grain size is exposed and easily corroded. Since the central part with few crystal grain boundaries tends to corrode toward the inside, the lattice breaks during use as a battery (sudden death). That is, the cycle life characteristics are deteriorated. Furthermore, the crystal grain boundaries (relatively many) of the dense layer are exposed by the destruction of the dense layer, whereby corrosion progresses and the lattice tends to stretch at high temperatures. Therefore, even if the techniques of Patent Document 1 and Patent Document 2 are randomly introduced, the problem is not improved.

Therefore, as a result of various studies, the present inventors made different thicknesses of the dense layers on both surfaces of the slab in the casting process (first process) of the slab, and the dense layer in the expanding process (third process). The die blade was inserted from the surface with the thinner side. As a result, the following four effects can be obtained.

First, since a dense layer can be sufficiently present on the surface of the sheet, the strength is high, the expand processability is high, and corrosion does not easily progress inside. Second, since the crystal grain size is large (the number of crystal grain boundaries is small) in the central portion in the thickness direction of the sheet, the absolute amount of corrosion is small, and the change in strength at high temperatures is small. Thirdly, since the dense layer on the surface where the stretch ratio becomes high during the expansion process is thickened, the dense layer is hardly broken, and the above-described first and second effects are not impaired.

Embodiments of the present invention will be described below.

(Embodiment)
1 to 3 are schematic views showing an example of a method for producing an electrode plate for a lead storage battery according to the embodiment. The electrode plate for a lead storage battery is manufactured through the following four steps.

In the first step, the molten metal 1 made of lead or a lead alloy is poured onto the drum 2 rotating in the direction of the arrow, and the molten metal is supplied by the refrigerant supplied into the drum 2 and the refrigerant discharged from the refrigerant discharge port 3. 1 is a process of continuously cooling 1 and casting a belt-like slab 4. The surface of the slab 4 that is cooled quickly has a relatively small crystal grain size, and the inside of the slab 4 that is cooled slowly has a relatively large crystal grain size.

The second step is a step in which the slab 4 is rolled with a pair or a plurality of pairs of rolling rollers 5 to adjust the thickness to produce a belt-like sheet 6.

In the third step, the sheet 6 is placed on the lower blade 8, and the die blade 7, which is the upper blade, is sequentially inserted into the sheet 6 from the upper surface side of the sheet 6 so as to be parallel to the longitudinal direction of the sheet 6. A strip-shaped expanded lattice 9 composed of a mesh portion formed by the strands 9a and a plain portion 9b by a method (reciprocal method) that develops in a direction perpendicular to the longitudinal direction of the sheet 6 while forming a plurality of cut lines. It is a process of producing. The plain portion 9b is not cut by the die blade 7.

In the fourth step, the active material paste 11 containing lead and a lead compound is discharged from the paste discharge port 10 whose position is fixed to the mesh portion excluding the plain portion 9b in the expanded lattice 9 that proceeds in the direction of the arrow. Then, after filling, drying, and cutting to a predetermined dimension, the electrode plate 12 is produced. In this step, a tab portion is formed from the plain portion 9b.

In the present embodiment, dense layers having a crystal grain size smaller than the central portion in the thickness direction are provided on both surfaces of the slab 4 in the first step so as to have different thicknesses on both surfaces, and the dense layer is thin in the third step. The die blade 7 is inserted from the surface of the surface. As shown in FIG. 7, when the cross section of the slab 4 or the sheet 6 is observed with a microscope, a dense layer 13 having a small crystal grain size is clearly observed on the surface as compared with the central portion 14 in the thickness direction where the crystal grain size is large.

In FIG. 1, when the surface of the slab 4 and the sheet 6 in contact with the drum 2 is α, and the surface of the slab 4 in contact with the refrigerant discharged from the refrigerant discharge port 3 is β, the dense layer on the surface α side depends on the refrigerant. It is easy to thicken. This is because the surface α on the drum 2 side that can continuously contact the refrigerant inside is relatively easier to cool, and the surface β that contacts the refrigerant intermittently discharged from the refrigerant discharge port 3. However, cooling is relatively difficult to proceed. Therefore, in order to thicken the dense layer on the surface β side, the amount of the refrigerant discharged from the refrigerant discharge port 3 may be increased to increase the cooling capacity on the surface β side. In addition, when there is a difference in the thickness of the dense layer on the surface α side and β side in the slab 4, this difference continues even if the sheet 6 is rolled.

In the reciprocating system in which the die blade 7 is reciprocated, the lower blade 8 is designed so as not to contact the portion of the sheet 6 where the die blade 7 descends. Accordingly, in the portion of the sheet 6 where the die blade 7 is inserted, the extension rate by the die blade 7 is greatly different between the surface where the die blade 7 enters and the opposite surface which is pushed down along the shape of the die blade 7 (die die). The surface where the blade 7 is inserted has a lower extension rate). Instead of the stretch rate, the amount that is extended or extended by the die blade 7 may be used, or it can be expressed by the stress applied when the die blade 7 is deformed. A high stretch rate means that the stretched amount is large and the stress is large.

That is, the dense layer existing on the surface opposite to the surface on which the die blade 7 enters (the surface that has a high extension rate and is pushed down) has a high extension rate and is greatly stretched, and thus is easily broken in the third step. . Specifically, the dense layer is broken in the vicinity where the cut is made, and fine cracks are formed on the surface. If the degree to which the dense layer is broken increases, the expand processability itself deteriorates, so that a problem in the manufacturing process that the strand is cut due to the occurrence of a crack occurs. Even if strand breakage does not occur, if the dense layer is broken and the central part with a large crystal grain size is exposed, the central part with few crystal grain boundaries tends to corrode toward the inside. If assembled and used in a storage battery, the grid of the electrode plate will corrode early. Accordingly, the lattice breaks early (sudden death), and the cycle life characteristics are deteriorated. Furthermore, the crystal grain boundaries (relatively many) of the dense layer are exposed in the destroyed portion of the dense layer, whereby corrosion of the dense layer proceeds and the lattice tends to stretch at high temperatures.

Therefore, as shown in FIG. 4 (corresponding to the portion γ in FIG. 2), the present inventors provided dense layers 13a and 13b on both surfaces of the slab 4 and the sheet 6 in the first step so as to have different thicknesses. In addition, in the third step, the die blade 7 is inserted from the surface having the thin dense layer 13a. As a result, the surface having the thick dense layer 13b is disposed on the surface that is relatively largely pressed down (the surface with a high extension rate). Even if the dense layer 13b is largely pushed down as shown in FIG. 4 or greatly stressed, the dense layer 13b is not broken because it has sufficient strength. Accordingly, when the thicknesses of the dense layers 13a and 13b on both sides are substantially the same, or the thickness difference between the dense layers 13a and 13b on both sides is ignored, the surface into which the die blade 7 is to be inserted is randomly selected (thick dense layer). Unlike the case of passing through the third step (so that the die blade 7 is inserted from the surface having 13b), the effects of the dense layers 13a and 13b (expanding processability is high and corrosion does not easily progress inside) and the crystal grain size Can be enjoyed together with the effect of the central portion 14 having a large (the absolute amount of corrosion is small, so the strength change is small at high temperatures).

The above is true for sheet 6 and lead or a lead-tin alloy. However, when a lead storage battery is used in a high temperature state or in a deep discharge state, antimony is added to 1.2 to When containing 2.0% by mass, the life of the lead-acid battery is extended, so it is preferable to add antimony to the sheet 6. When antimony is less than 1.2% by mass, the effect of extending the life is not clear. When it exceeds 2.0% by mass, the increase in the life is almost the same as the case of containing 2.0% by mass, but the expand processability is improved. The occurrence of defects in the expanding process increases and decreases.

As one aspect for embodying the present embodiment, the cooling capacity on the drum 2 side is increased in comparison with that on the refrigerant discharge port 3 side in the first step, and then the drum 2 is cooled in the third step. There is an expanding method in which the surface α side is in contact with the lower blade 8 (so that the die blade 7 is put in the surface β cooled by the refrigerant discharge port 3). In the case of adopting this mode, as shown in FIGS. 1 and 2, α which is the upper surface in the first and second steps needs to be the lower surface in the third step.

As another mode for embodying the present embodiment, the cooling capacity on the refrigerant discharge port 3 side is increased in comparison with that on the drum 2 side in the first step, and the cooling is performed by the refrigerant discharge port 3 in the third step. There is a method of expanding so that the surface β side touches the lower blade 8 (so that the die blade 7 is put in the surface α cooled by the drum 2). When this mode is adopted, it is not necessary to reverse the surface in the first to third steps. However, as described above, since the drum 2 generally has a higher cooling capacity, the cooling with the refrigerant discharge port 3 side is performed. The capacity balance needs to be carefully adjusted.

Here, in the third step, the ratio A / B between the layer thickness A of the dense layer 13a and the layer thickness B of the dense layer 13b is desirably 0.14 or more and 0.50 or less. Furthermore, in the third step, it is desirable that the ratio (A + B) / C of the thickness C of the sheet 6 and the sum A + B of the layer thicknesses of the dense layers 13a and 13b is 0.15 or more and 0.40 or less. If the ratios A / B and (A + B) / C are within the preferred ranges, the composition ratio of the thicknesses of the dense layers 13a and 13b in the sheet 6 is optimized and corrosion is less likely to proceed, resulting in higher cycle life characteristics. .

Whether or not the lead storage battery electrode plate has undergone the manufacturing method of the present embodiment can be clearly determined even after the lead storage battery described in detail later is configured. The presence of the dense layers 13a and 13b and the central portion 14 and the layer thickness thereof can be detected and measured by polishing the cross section of the expanded lattice 9 (particularly, the strand 9a) and observing the crystalline state. As is clear from FIGS. 2 to 4, the two sides on the upper side (the side close to the tab portion) of the mesh of the expanded lattice 9 (substantially rhombus made of strands 9a) are the surfaces on which the die blade 7 enters. Since this is the opposite surface (the surface that has a high extension rate, the surface to be pushed down), it is determined whether the dense layer 13a observed by the above method exists on either the upper or lower side of the substantially rhombic mesh of the expanded lattice 9 It can be specified whether or not the die blade 7 is inserted along the method of the form.

This will be described with reference to FIG. FIG. 6 is a front view of the electrode-plate-shaped expanded lattice 22 that is not filled with an active material. The expanded lattice 11 has a quadrangular shape, and tab portions 23 protrude from the upper side shown in FIG. When the expanded lattice 22 is set up vertically with the tab portion 23 for electrical connection with another electrode plate facing upward, the surface 25 facing upward in the strand 24 constituting the mesh has a thickness of the dense layer. It is a small surface on which the die blade 7 is placed. The face 26 facing downward is the face where the dense layer is thick. Note that the front surface (surface shown in FIG. 6) and the back surface of the strand 24 in the vertically expanded lattice 22 are surfaces cut by a die blade.

FIG. 5 is an external view showing the lead storage battery of this embodiment. The electrode plate group 16 is configured by using the electrode plate 12 for a lead storage battery of the present embodiment for at least one of the positive electrode plate 16a and the negative electrode plate 16b and confronting them with the separator 16c. A plurality of electrode plate groups 16 are inserted into each cell chamber 17 of the battery case 15 provided with a plurality of cell chambers 17 by partitioning a space surrounded by the outer wall 15b and the bottom (not shown) with a partition wall 15a. By connecting the different polarities of the adjacent electrode plate groups 16 with the connecting parts 18, the number of electrode plate groups 16 is connected in series. When the lid 20 is sealed at the opening of the battery case 15, a pole column (not shown) connected to one polarity of the electrode plate group 16 at both ends is connected to a bushing (not shown), whereby a terminal 19 is configured. Finally, by injecting dilute sulfuric acid, which is an electrolyte (not shown), from a hole (not shown, disposed immediately above each cell chamber) provided in the lid 20, and sealing with a liquid stopper 20a to form, It becomes the lead acid battery of this embodiment.

Here, as the positive electrode plate 16a, an active material paste containing lead and lead oxide can be used. The negative electrode plate 16b can be made of an active material paste containing lead and lead oxide, and further containing barium sulfate, carbon black, and a lignin compound. Polyethylene or the like can be used for the separator 16c, and polypropylene (PP) or acrylonitrile-butadiene-styrene copolymer resin (ABS) can be used for the battery case 15 and the lid 20. Further, lead or various lead alloys can be used for the connection component 18 and the terminal 19. Furthermore, what has functions, such as explosion-proof, can be used for the liquid spout 20a. The specific gravity of dilute sulfuric acid used as the electrolyte is preferably 1.2 to 1.4 g / ml.

Example 1
The molten metal 1 made of a lead-calcium alloy is poured onto the rotating drum 2, and the molten metal 1 is continuously cooled with the cooling water supplied into the drum 2 and the cooling water discharged from the refrigerant discharge port 3. The belt-like slab 4 was cast (first step). At this time, the molten metal 1 contained 0.07% by mass of Ca and 1.5% by mass of Sn.

Then, the slab 4 was rolled with a plurality of pairs of rolling rollers 5 and adjusted so that the thickness C became 1.0 mm, thereby producing a belt-like sheet 6 (second step).

By supplying the belt-like sheet 6 with its front and back reversed and sequentially inserting the dice blades 7 from the upper surface of the sheet 6 placed on the lower blade 8, a plurality of zigzag-like plurals are formed in parallel with the longitudinal direction of the sheet 6. A strip-shaped expanded lattice 9 composed of a mesh portion formed by the strands 9a and a plain portion 9b was produced by a reciprocating method that developed in a direction perpendicular to the longitudinal direction of the sheet 6 while forming a cut (third) Process).

Finally, for the portion (mesh portion) of the expanded lattice 9 excluding the plain portion 9b, the raw material lead powder mainly composed of mixed powder of lead and lead oxide (Pb, PbO, Pb ₃ O ₄ ) is refined with sulfuric acid. The active material paste 11 produced by adding water was discharged from the paste discharge port 10, filled, dried, and then cut to a predetermined size to produce the electrode plate 12 (positive electrode plate 16a) (fourth plate) Process).

As a result of analyzing the expanded lattice 9 after the third step, the layer thickness A of the dense layer 13a formed on the upper surface of the strand when the expanded lattice 9 is set up vertically with the tab portion facing upward is The thickness B of the dense layer 13b formed on the lower surface of the strand was 0.05 mm (the ratio A / B was 0.71, the ratio (A + B) / C was 0.12). .

Using the positive electrode plate 16a described above and the negative electrode plate 16b prepared by a conventional method (a known method), an automotive lead acid battery (55D23) according to the description of the embodiment was produced.

(Example 2)
Compared to Example 1, by increasing the amount of cooling water supplied to the inside of the drum 2, the layer thickness B of the dense layer 13 b is 0.10 mm (ratio A / B is 0.50, ratio (A + B) / C is A lead-acid battery was produced in the same manner as in Example 1 except that 0.15).

(Example 3)
Compared to Example 2, the thickness B of the dense layer 13b is 0.15 mm (ratio A / B is 0.33, ratio (A + B) / C) by further increasing the amount of cooling water supplied into the drum 2. A lead-acid battery was produced in the same manner as in Example 2, except that 0.20).

Example 4
Compared to Example 3, the thickness B of the dense layer 13b is 0.20 mm (ratio A / B is 0.25, ratio (A + B) / C) by further increasing the amount of cooling water supplied to the inside of the drum 2. Was changed to 0.25), and a lead storage battery was produced in the same manner as in Example 3.

(Example 5)
Compared to Example 4, the layer thickness B of the dense layer 13b is 0.30 mm (ratio A / B is 0.17, ratio (A + B) / C) by further increasing the amount of cooling water supplied to the inside of the drum 2. A lead-acid battery was produced in the same manner as in Example 4 except that 0.35).

(Example 6)
Compared to Example 5, the layer thickness B of the dense layer 13b is 0.35 mm (ratio A / B is 0.14, ratio (A + B) / C) by further increasing the amount of cooling water supplied to the inside of the drum 2. A lead-acid battery was produced in the same manner as in Example 5 except that the value was 0.40).

(Example 7)
Compared to Example 6, the layer thickness B of the dense layer 13b is 0.40 mm (ratio A / B is 0.13, ratio (A + B) / C) by further increasing the amount of cooling water supplied to the inside of the drum 2. Was made into the lead acid battery similarly to Example 6 except having set it as 0.45).

(Example 8)
The lead-acid battery is the same as in Example 4 except that the composition of the molten metal 1 is set to Ca: 0.07% by mass, Sn: 1.5% by mass, and Sb: 0.7% by mass with respect to Example 4. Was made.

Example 9
The lead acid battery is the same as in Example 4 except that the composition of the molten metal 1 is set to Ca: 0.07 mass%, Sn: 1.5 mass%, and Sb: 1.2 mass% with respect to Example 4. Was made.

(Example 10)
The lead-acid battery is the same as in Example 4 except that the composition of the molten metal 1 is set to Ca: 0.07% by mass, Sn: 1.5% by mass, and Sb: 1.6% by mass with respect to Example 4. Was made.

(Example 11)
The lead-acid battery is the same as in Example 4 except that the composition of the molten metal 1 is set to Ca: 0.07% by mass, Sn: 1.5% by mass, and Sb: 2.0% by mass with respect to Example 4. Was made.

(Example 12)
The lead acid battery is the same as in Example 4 except that the composition of the molten metal 1 is set to Ca: 0.07% by mass, Sn: 1.5% by mass, and Sb: 2.5% by mass with respect to Example 4. Was made.

(Comparative Example 1)
Compared to the fourth embodiment, by reducing the amount of cooling water supplied to the inside of the drum 2, the layer thickness B of the dense layer 13b is 0.05 mm (the ratio A / B is 1, the ratio (A + B) / C is 0.00. A lead-acid battery was produced in the same manner as in Example 1 except that 10).

(Comparative Example 2)
In contrast to Example 4, the thickness A of the dense layer 13a is 0.20 mm and the thickness B of the dense layer 13b is 0.05 mm (ratio A / B) by supplying the belt-like sheet 6 without being reversed. A lead storage battery was produced in the same manner as in Example 4 except that 4 was changed to 4).

(Table 1) shows the rate of occurrence of defective cutting of the strands 9a in the third step (the number of defective electrode plates in the total number of positive plates 16a produced in the fourth step) for each condition described above.

Moreover, the light load life test prescribed | regulated by JIS specification (D5301) was implemented in the gaseous phase with an atmospheric temperature of 75 degreeC using the lead storage battery of each conditions mentioned above. The number of cycles until the voltage at the 5th second in the judgment discharge every 480 cycles decreases to 7.2 V is described in (Table 1) together with the result of confirming the presence or absence of an internal short circuit by disassembling the lead storage battery that has reached the end of its life.

As is clear from (Table 1), dense layers having different thicknesses are provided on both surfaces of the slab 4 and reflected on the sheet 6 (the layer thickness is the dense layer 13a <dense layer 13b). In Examples 1 to 12 in which the blade 7 is inserted, the die blade 7 is inserted from the surface of the comparative example 1 in which the dense layers 13a and 13b have the same layer thickness and the dense layer 13b side where the layer thickness is large. Good cycle life characteristics were exhibited with respect to Comparative Example 2. In particular, in these examples, there was no internal short-circuit (generated when the expanded lattice 9 of the positive electrode plate 16a extends and contacts the negative electrode plate 16b at a high temperature) that suddenly dies.

In particular, the ratio A / B between the layer thickness A of the dense layer 13a and the layer thickness B of the dense layer 13b is 0.14 to 0.50, and the sum of the thickness C of the sheet 6 and the layer thicknesses of the dense layers 13a and 13b. In Examples 2 to 6 and 8 to 12 (particularly Examples 3 to 5 and 8 to 12) in which the ratio (A + B) / C with respect to A + B is 0.15 or more and 0.40 or less, the dense layer 13b is thinned. In particular, the cycle life is eliminated by wiping out the problem (corrosion of the central portion 14 starting from the fracture in the third step) and the problem (increased corrosion amount due to a large number of crystal grain boundaries) when the thickness is increased. The characteristics were good. In addition, Examples 8 to 12 (especially Examples 9 to 12) in which Sb was added to the molten metal 1 were particularly good in cycle life characteristics, but as the Sb content increased, the expanding process defect rate increased. It was. However, if the Sb content is 2.0% by mass or less, the defective rate of the expanding process has no practical problem.

(Other embodiments)
The above embodiments and examples are examples of the present invention, and the present invention is not limited to these examples. The lead storage battery may have a structure other than that shown in FIG. The raw material of the expanded lattice is not limited to the lead-calcium alloy, and the alloy composition is not limited to the above composition.

According to the present invention, it is possible to provide a lead storage battery having a high cycle life characteristic and not easily short-circuited by using an electrode plate having high productivity (expanding processability). The contribution of is extremely high.

DESCRIPTION OF SYMBOLS 1 Molten metal 2 Drum 3 Refrigerant discharge port 4 Slab 5 Rolling roller 6 Sheet 7 Die blade 8 Lower blade 9 Expanded lattice 9a Strand 9b Plain part 10 Paste discharge port 11 Active material paste 12 Electrode 13 Dense layer 13a, 13b Dense layer 14 Center Part 15 Battery case 15a Bulkhead 15b Outer wall 16 Electrode plate group 16a Positive electrode plate 16b Negative electrode plate 16c Separator 17 Cell chamber 18 Connection component 19 Terminal 20 Lid 20a Liquid plug 22 Electrode plate-shaped expanded lattice 23 Tab part 24 Strand 25 Strand upper side surface 26 Lower side of the strand

Claims

An expanded grid of lead or lead alloys;
An electrode plate for a lead-acid battery comprising an active material filled in the expanded lattice,
The expanded lattice is a quadrilateral and has a tab portion protruding from one side;
When the expanded lattice is erected vertically with the side having the tab portion as the upper side, the surface facing upward and the surface facing downward in the strand of the lattice is a dense crystal grain having a smaller crystal grain size than the central portion of the strand Has a layer on the surface,
The electrode plate for a lead storage battery, wherein the dense layer is thinner on the surface facing upward of the strand than on the surface facing downward.
The thickness A of the dense layer on the surface facing upward of the strand and the thickness B of the dense layer on the surface facing downward have a relationship that A / B is 0.14 or more and 0.50 or less. The electrode plate for a lead storage battery according to claim 1.
Thickness between the dense layer thickness A of the surface facing the strand, the thickness B of the dense layer of the surface facing downward, and the thickness between the surface facing upward and the surface facing downward of the strand The electrode plate for a lead storage battery according to claim 1 or 2, wherein C has a relationship in which (A + B) / C is 0.15 or more and 0.40 or less.
The lead-acid battery electrode plate according to any one of claims 1 to 3, wherein the lead alloy contains antimony.
The electrode plate for a lead storage battery according to claim 4, wherein antimony is contained in the lead alloy in an amount of 2% by mass or less.
A lead-acid battery using the electrode plate for a lead-acid battery according to any one of claims 1 to 5 as at least one of a positive electrode plate and a negative electrode plate and facing the counter electrode plate via a separator.
A first step of continuously cooling a molten metal made of lead or a lead alloy to cast a strip-shaped slab;
A second step of rolling the slab to produce a strip-shaped sheet;
A third step of producing a strip-shaped expanded lattice by a reciprocal system that develops in a direction perpendicular to the longitudinal direction of the sheet while forming a plurality of staggered cuts parallel to the longitudinal direction of the sheet;
And a fourth step of producing an electrode plate by filling an active material paste containing lead and a lead compound into the expanded lattice and drying, and then cutting the electrode plate to a predetermined size. And
In the first step, dense layers having a crystal grain size smaller than the central portion are provided on both surfaces of the slab with different thicknesses on both surfaces,
In the third step, the lead plate for a lead-acid battery, wherein the cut is formed by inserting a die blade from the surface where the dense layer is thin.
The ratio A / B between the layer thickness A of the thinner dense layer and the other layer thickness B in the third step is 0.14 or more and 0.50 or less. The manufacturing method of the electrode plate for lead acid batteries currently used.
The ratio (A + B) / C between the thickness C of the sheet in the third step and the sum A + B of the thickness A of the thinner dense layer and the thickness B of the other layer is 0.15 or more and 0.40 or less. 9. The method for producing a lead-acid battery electrode plate according to claim 7 or 8, wherein the method is provided.