JP2020053298A - Lead storage battery - Google Patents

Abstract

To provide a lead storage battery that suppresses an increase in internal resistance and allows a charged state or a deteriorated state to be accurately determined by a method for measuring internal resistance.SOLUTION: A lead storage battery includes an electrode plate group 1 in which a plurality of positive electrode plates 10 having a positive electrode active material containing lead dioxide and a plurality of negative electrode plates 20 having a negative electrode active material containing metallic lead are alternately laminated via a separator 30. The electrode plate group 1 is immersed in an electrolyte. The flatness of the positive electrode plates 10 after chemical formation is 4.0 mm or less. Distances between adjacent positive electrode plates 10 and negative electrode plates 20 are each 0.60 mm or more and 0.90 mm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lead storage battery.

  In the recent automobile market, vehicles equipped with a charge control system and an idling stop system for the purpose of improving fuel efficiency and reducing emissions (hereinafter referred to as "charge control vehicles" and "idle stop vehicles") Is sometimes the mainstream. In these vehicles, the state of charge or deterioration of the lead storage battery is determined on the vehicle side, and based on the result, charging / discharging of the lead storage battery and idling stop of the engine are controlled.

  However, when a charge control system or an idling stop system is used, a large load is applied to the lead storage battery, so that it is easy to shorten the service life. For example, in any of the systems, the charge and discharge of the lead storage battery are frequently repeated, so that the active material may be softened or dropped, and the capacity may be reduced at an early stage. In addition, in an idling stop vehicle, the state of charge of the lead-acid battery is liable to decrease.If the charge-acceptability of the lead-acid battery is insufficient, sulfation in which passivated lead sulfate accumulates on the surface of the electrode plate progresses, and the internal resistance increases. , And there is a possibility that the capacity may be reduced at an early stage.

  Under such circumstances, lead storage batteries used in charge control vehicles and idling stop vehicles are required to have high durability and charge acceptability, as well as accuracy in determining the state of charge and the state of deterioration. As a method of determining the state of charge or the state of deterioration of a lead storage battery, a method of measuring the internal resistance of the lead storage battery is known. However, since the internal resistance of the lead storage battery may increase due to various factors other than the charged state and the deteriorated state, it is not easy to accurately determine the charged state and the deteriorated state.

JP 2017-92001 A

  An object of the present invention is to provide a lead-acid battery in which a rise in internal resistance is suppressed and a charged state or a deteriorated state can be accurately determined by a method of measuring internal resistance.

  In the lead storage battery according to one embodiment of the present invention, a positive electrode plate having a positive electrode active material containing lead dioxide and a negative electrode plate having a negative electrode active material containing metallic lead are alternately stacked with a plurality of separators interposed therebetween. The electrode group is immersed in an electrolytic solution, the flatness of the positive electrode plate after formation is 4.0 mm or less, and the distance between the adjacent positive electrode plate and negative electrode plate is 0.1 mm. The gist should be 60 mm or more and 0.90 mm or less.

  In the lead storage battery according to the present invention, an increase in the internal resistance is suppressed, and the state of charge and the state of deterioration can be accurately determined by a method of measuring the internal resistance.

1 is a partial cross-sectional view illustrating a structure of a lead storage battery according to an embodiment of the present invention. It is a figure explaining the measuring method of the flatness of an electrode plate. FIG. 3 is a diagram of a positive electrode plate schematically showing the occurrence of a curve due to a difference in the degree of thick coating of a positive electrode active material.

  An embodiment of the present invention will be described. The embodiment described below is an example of the present invention, and the present invention is not limited to the embodiment. In addition, various changes or improvements can be made to the present embodiment, and embodiments with such changes or improvements can be included in the present invention.

As a result of intensive studies by the present inventor, new findings have been found regarding an increase in the internal resistance of the lead storage battery, and will be described in detail below.
In a lead storage battery, an electrode plate group in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked via a separator is housed in a battery case under a predetermined group pressure. At this time, a ribbed separator provided with a rib on the base surface is used as an electrode plate because a diffusion channel for electrolyte and a gas discharge channel required for the charge / discharge reaction are required between the electrodes of the electrode group. In general, a method is used in which a gap is provided to be a diffusion flow path for an electrolytic solution or a discharge flow path for a gas by being interposed therebetween.

  However, even when such a ribbed separator is used, the internal resistance may be maintained at an increased level and may not be easily reduced. As a result of an investigation by the present inventor for a lead-acid battery having such a high internal resistance, the plates constituting the plate group are curved, gas bubbles are caught on the edges of the curved plate, and the plate It turned out that it was in the state of having adhered to. Then, as a result of the gas bubbles adhering to the electrode plates, the gas is confined and stays in the electrode plate group, and the contact area between the active material and the electrolytic solution (that is, the area of the portion where the reaction occurs) decreases. It has been found that the internal resistance of the lead storage battery increases.

Further, it was also found that since the distance between the adjacent electrode plates became smaller due to the curvature, the gas was easily trapped between the electrode plates, and it was difficult for the gas to go out of the electrode group.
Furthermore, it has been found that there is a lead storage battery whose internal resistance does not remain high even when the electrode plate is curved. From this fact, it was found that depending on the magnitude and shape of the curvature of the electrode plate, gas might not easily stay in the electrode plate group.

  The cause of the bending of the electrode plate has been found by the study of the present inventors as follows. When manufacturing an electrode plate by forming an active material layer made of an active material on the surface of the substrate, an attempt is made to form an active material layer of the same thickness on both plate surfaces of the substrate, but the same thickness is formed on both plate surfaces. It is not easy to form an active material layer having a different thickness, and an active material layer having a different thickness may be formed. For example, in the example of FIG. 3, the thickness of the active material layer 102B formed on the left plate surface 101b is larger than the thickness of the active material layer 102A formed on the right plate surface 101a of the substrate 101 of the electrode plate 100. It is bigger.

  When the thicknesses of the active material layers 102A and 102B formed on the two plate surfaces 101a and 101b of the substrate 101 are different from each other, as shown in FIG. Deform. Then, as shown in FIG. 3, the electrode plate is formed such that the plate surface 101b with the larger thickness of the active material layer 102B becomes a convex surface and the plate surface 101a with the smaller thickness of the active material layer 102A becomes a concave surface. 100 curves.

From the above study results, the present inventor has found that if the curvature of the electrode plate is suppressed, the increase in internal resistance due to formation, charging and discharging, etc. is suppressed, and the state of charge and the state of deterioration are accurately determined by a method of measuring the internal resistance. The present inventors have found that a lead-acid battery capable of performing the above-mentioned operations can be obtained, and have completed the present invention.
That is, in the lead storage battery according to one embodiment of the present invention, a plurality of positive electrode plates having a positive electrode active material containing lead dioxide and a plurality of negative electrode plates having a negative electrode active material containing metal lead are interposed via a separator. The electrode group is a lead-acid battery immersed in an electrolytic solution, and the flatness of the positive electrode plate after formation is 4.0 mm or less. It is preferable that the flatness of all the positive electrode plates in the electrode plate group be 4.0 mm or less.
In addition, between the positive electrode plate and the negative electrode plate, the positive electrode plate is more likely to be curved during chemical formation. From this, it is important to control the flatness of the positive electrode plate to be small in order to achieve the object of the present invention.

  The structure of the lead storage battery according to one embodiment of the present invention will be described in more detail with reference to FIG. The lead storage battery according to the present embodiment includes an electrode plate group 1 in which a plurality of positive electrode plates 10 and a plurality of negative electrode plates 20 are alternately stacked with a separator 30 interposed therebetween. The electrode plate group 1 is housed in the battery case 41 together with an electrolytic solution (not shown) so that the laminating direction is along the horizontal direction (that is, the plate surfaces of the positive electrode plate 10 and the negative electrode plate 20 are along the vertical direction). It is immersed in the electrolytic solution in the battery case 41.

  The positive electrode plate 10 is, for example, filled with a positive electrode active material containing lead dioxide in the openings of a plate-like lattice made of a lead alloy, and on the both plate surfaces of the plate-like lattice made of a lead alloy, An active material layer made of the contained positive electrode active material was formed. The negative electrode plate 20, for example, while filling the negative electrode active material containing metal lead into the openings of the plate-shaped lattice made of a lead alloy, while adding metal lead to both plate surfaces of the plate-shaped lattice made of a lead alloy. An active material layer composed of a contained negative electrode active material was formed. The plate-like lattice body serving as the substrate of the positive electrode plate 10 and the negative electrode plate 20 can be manufactured by a casting method, a punching method, or an expanding method. The separator 30 is, for example, a porous film made of resin, glass, or the like.

  Current collecting ears 11 and 21 are formed on the upper ends of the positive electrode plate 10 and the negative electrode plate 20, respectively. The current collecting ears 11 of each positive electrode plate 10 are connected by a positive electrode strap 13, and the current collecting ears of each negative electrode plate 20 are collected. The ears 21 are connected by a negative strap 23. The positive strap 13 is connected to one end of the positive terminal 15, the negative strap 23 is connected to one end of the negative terminal 25, and the other end of the positive terminal 15 and the other end of the negative terminal 25 are connected to the opening of the battery case 41. It penetrates a lid 43 that closes the part, and is exposed to the outside of the case body of the lead storage battery including the battery case 41 and the lid 43.

  In the lead storage battery according to the present embodiment having such a structure, the flatness of the positive electrode plate 10 after formation is set to 4.0 mm or less. As the value of the flatness is smaller, the positive electrode plate 10 is flatter, and gas bubbles are less likely to adhere to the surface of the positive electrode plate 10. If the flatness of the positive electrode plate 10 after formation is 4.0 mm or less, the gas is easily discharged to the outside of the electrode plate group 1, so that the increase in the internal resistance of the lead-acid battery is suppressed and the internal resistance is measured. This makes it possible to accurately determine the state of charge and the state of deterioration.

The method of making the flatness of the positive electrode plate 10 after chemical formation 4.0 mm or less is not particularly limited, and a lead-acid battery may be manufactured by a method of suppressing bending due to chemical formation, or the positive electrode plate 10 may be bent by chemical formation. May be corrected to make the flatness 4.0 mm or less.
As described above, if the thicknesses of the active material layers formed on both surfaces of the positive electrode plate are different, the positive electrode plate is curved during chemical formation, so that the active material layers having substantially the same thickness are formed on both plate surfaces. By subjecting the positive electrode plate to chemical conversion, the flatness can be reduced to 4.0 mm or less while suppressing the curvature.

Examples of the method for forming the active material layers having the same thickness on both plate surfaces include the following two methods. The first method is to cut the larger active material layer of the positive electrode plate before laminating the positive electrode plate in which the active material layers having different thicknesses are formed on both plate surfaces with the negative electrode plate and the separator. This is a method of making the thickness of the active material layer smaller than that of the smaller active material layer.
If it is attempted to form active material layers on both surfaces of the positive electrode plate at the same time, it is difficult to form active material layers of the same thickness. This is a method in which an active material layer having the same thickness is formed by filling an opening one surface at a time to form an active material layer.

  However, when the flatness of the positive electrode plate 10 after the formation is less than 0.5 mm, the gas is easily discharged to the outside of the electrode plate group 1, but when the electrode plate group 1 is accommodated in the battery case 41, The group pressure applied to the electrode plate group 1 by the inner wall surface of the tank 41 may be insufficient. As a result, the positive electrode active material is likely to be softened or dropped, and the performance and life of the lead storage battery may be reduced. Therefore, it is preferable that the flatness of the positive electrode plate 10 after the formation be 0.5 mm or more.

  The flatness of the positive electrode plate can be measured by a method specified in JIS B0419: 1991. That is, as shown in FIG. 2, the positive electrode plate is positioned such that the plate surface of the positive electrode plate and the flat surface of the base are substantially parallel to each other on the plane of the base, and the convex surface of the curved positive electrode plate faces upward. Is placed, and the distance h between the vertex of the convex surface of the curved positive electrode plate (the part farthest from the plane of the base) and the plane of the base is measured. Then, a value obtained by subtracting the thickness of the positive electrode plate from the distance h is defined as flatness.

  It should be noted that even in the conventional lead storage battery, the electrode plate is curved, and no lead storage battery having an electrode plate having a flatness of 4.0 mm or less has not been confirmed. For example, although the flat electrode plate which is not curved is drawn in the drawing of Patent Literature 1, it is drawn flat for convenience, and the electrode plate is actually not flat but curved. Further, the knowledge that the gas is confined inside the electrode group due to the curvature of the electrode plate and the internal resistance rises has not been known at all by those skilled in the art.

  As described above, in the lead storage battery according to the present embodiment, an increase in internal resistance due to formation, constant-voltage charging, and the like is unlikely to occur, and an internal resistance after charging decreases quickly. In addition, the lead storage battery according to the present embodiment also has excellent durability and high charge acceptability (high charging efficiency and can be charged in a short time). Therefore, the lead storage battery according to the present embodiment is suitable as a lead storage battery that is mounted on a vehicle that performs charge control such as a charge control vehicle and an idling stop vehicle and is mainly used in a partially charged state. Note that the partially charged state is a state where the state of charge is, for example, more than 70% and less than 100%.

  The lead storage battery according to the present embodiment is used not only as a power source for starting an internal combustion engine of a vehicle, but also as an electric vehicle, an electric forklift, an electric bus, an electric motorcycle, an electric scooter, a small electric moped, a golf cart, an electric It can also be used as a power source for locomotives and the like. Furthermore, the lead storage battery according to the present embodiment can also be used as a lighting power supply and a standby power supply. Alternatively, it can also be used as a power storage device for electric energy generated by solar power generation, wind power generation, or the like.

In the lead storage battery according to the present embodiment, the flatness of the negative electrode plate after formation is not particularly limited, but may be as small as the positive electrode plate after formation, for example, 4.0 mm. The following may be used. Further, the flatness of the positive electrode plate after formation and the flatness of the negative electrode plate after formation may be the same or different, but are preferably different. For example, if the ratio of the flatness of the negative electrode plate to the flatness of the positive electrode plate is set to 50% or more and 80% or less on average in the electrode plate group, gas hardly stays in the electrode plate group, and Gas emission is likely to occur.
Hereinafter, the lead storage battery according to the present embodiment will be described in more detail.

[About the curved shape of the positive electrode plate]
As described above, depending on the curved shape of the positive electrode plate, gas may not easily stay in the electrode plate group, and there is a lead storage battery whose internal resistance does not remain high even if the positive electrode plate after formation is curved. . For example, if the apex of the convex surface of the curved positive electrode plate is curved such that it is located below the vertical center of the positive electrode plate arranged in the lead-acid battery, the outlet of the gas bubble and Since it can be said that the degree of curvature of the upper portion is smaller than the vertical center, the gas hardly stays in the electrode group.

  That is, if the degree of curvature of the portion above the vertical center of the positive electrode plate, which is an outlet when gas bubbles are discharged from the electrode group to the outside, is small, the gas stays in the electrode group. Since it is difficult to discharge the lead storage battery, an increase in the internal resistance of the lead storage battery is suppressed. Therefore, if the flatness of the portion above the vertical center of the positive electrode plate after formation is 4.0 mm or less, the effect of suppressing an increase in the internal resistance of the lead-acid battery is exhibited.

[About the density of the positive electrode active material]
The density of the positive electrode active material included in the positive electrode plate is not particularly limited, but is preferably from 4.2 g / cm ^{3 to} 4.6 g / cm ³ , and preferably from 4.4 g / cm ^{3 to} 4.6 g / cm ^3. More preferably, it is not more than cm ³ . If the density of the positive electrode active material is within the above numerical range, the positive electrode active material is unlikely to soften or fall off, so that the effect of improving the life of the lead storage battery is exhibited.

[About electrolyte]
The composition of the electrolytic solution is not particularly limited, and an electrolytic solution used for a general lead-acid battery can be applied without any problem.However, in order to make the charge acceptability of the lead-acid battery excellent, The electrolyte preferably contains aluminum, and the content of aluminum ions in the electrolyte is preferably 0.01 mol / L or more. However, when the content of the aluminum ion in the electrolyte is high, it is difficult for the gas to be discharged to the outside from the electrode plate group. Therefore, the content of the aluminum ion in the electrolyte should be 0.3 mol / L or less. preferable.
Further, the electrolyte may contain sodium ions. The content of sodium ions in the electrolytic solution can be 0.002 mol / L or more and 0.05 mol / L or less.

[Group pressure applied to electrode group]
As described above, when the electrode group is accommodated in the battery case, a group pressure is applied to the electrode group by the inner wall surface of the battery case. However, if the group pressure is insufficient, the positive electrode active material is softened. And the battery may easily fall off, and the performance and life of the lead storage battery may be reduced. On the other hand, if the group pressure is too high, gas may stay in the positive electrode active material, and the internal resistance of the lead storage battery may increase. Therefore, the group pressure applied to the electrode plate group is preferably set to 10 kPa or less.

[Lead dioxide contained in the positive electrode active material]
Lead dioxide includes an orthorhombic α phase (α-lead dioxide) and a tetragonal β phase (β-lead dioxide). The ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide contained in the positive electrode active material is preferably 20% or more and 40% or less. With such a configuration, the stratification of the electrolytic solution is unlikely to occur, so that the effect of improving the life of the lead storage battery is exhibited.

  α-lead dioxide has a low discharge capacity due to poor porosity and a small specific surface area, but has a low softening rate due to the extremely gradual collapse of crystals. On the other hand, β-lead dioxide is rich in porosity and has a large specific surface area, so that it has a large discharge capacity, but on the other hand, the crystal collapses quickly and the softening rate is high. Therefore, in order to achieve both long life of the lead storage battery and excellent discharge capacity, the ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide contained in the positive electrode active material is required. It is preferable that α-lead dioxide and β-lead dioxide are dispersed in the positive electrode active material so as to be 20% or more and 40% or less.

  If the ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide is less than 20%, the life of the lead storage battery may be insufficient. On the other hand, when the ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide is more than 40%, the capacity of the lead storage battery may decrease.

[About the pores of the positive electrode active material]
When the positive electrode active material is porous, the average diameter of the pores of the positive electrode active material is preferably 0.07 μm or more and 0.20 μm or less, and the porosity of the positive electrode active material is 30% or more and 50% or less. Preferably, there is.

  If the average diameter of the pores of the positive electrode active material is less than 0.07 μm, the utilization rate of the active material may decrease. On the other hand, when the average diameter of the pores of the positive electrode active material is larger than 0.20 μm, the internal resistance of the lead storage battery may increase. Further, the softening of the positive electrode active material may easily occur. The method for measuring the average diameter of the pores of the positive electrode active material is not particularly limited, but can be measured, for example, by a mercury intrusion method.

If the porosity of the positive electrode active material is less than 30%, sulfuric acid hardly permeates into the active material, and the utilization rate of the active material may be reduced. On the other hand, if the porosity of the positive electrode active material exceeds 50%, the life of the active material may be reduced because the density of the active material is reduced.
The method for measuring the porosity of the positive electrode active material is not particularly limited, but can be measured, for example, by a mercury intrusion method.

[About surface roughness Ra of the surface of the positive electrode plate]
The surface roughness Ra of the surface of the positive electrode plate is not particularly limited, but is preferably 0.20 mm or less. If the surface roughness Ra of the surface of the positive electrode plate is larger than 0.20 mm, the gas tends to stay in the concave and convex portions of the surface of the positive electrode plate, and the internal resistance may increase. However, if the surface roughness Ra of the surface of the positive electrode plate is less than 0.05 mm, the sedimentation speed of sulfuric acid generated on the surface of the positive electrode plate during charging is increased, and there is a possibility that stratification of the electrolytic solution is likely to occur.

[About distance between adjacent positive electrode plate and negative electrode plate]
The distance between the adjacent positive electrode plate and negative electrode plate in the electrode plate group is not particularly limited, but is preferably 0.60 mm or more and 0.90 mm or less between any of the electrode plates.

If the distance between the adjacent positive electrode plate and negative electrode plate is less than 0.60 mm, the amount of sulfuric acid existing between the electrode plates is reduced, so that the capacity of the lead storage battery may be reduced. On the other hand, if the distance between the adjacent positive electrode plate and negative electrode plate is larger than 0.90 mm, the liquid resistance increases, and the internal resistance of the lead storage battery may increase. Moreover, the internal resistance of the lead storage battery may increase due to the stagnation of the gas.
The distance between the adjacent positive electrode plate and negative electrode plate is preferably 0.60 mm or more and 0.90 mm or less, but in the present invention, the electrode plate is provided at any position on the plate surface of the electrode plate. It means that the distance between them is 0.60 mm or more and 0.90 mm or less.

[About the content of iron contained in the positive electrode active material in a fully charged state]
The content of iron contained in the positive electrode active material in the fully charged state (for example, after chemical conversion) of the lead storage battery is not particularly limited, but is preferably 3.5 ppm or more and 20.0 ppm or less. When iron is contained in the positive electrode active material, gas is easily generated on the positive electrode plate. Then, the generated gas rises in the electrolytic solution, whereby the electrolytic solution is stirred, and stratification is suppressed. If the content of iron contained in the positive electrode active material in the fully charged state of the lead storage battery is within the above range, the amount of gas generated on the positive electrode plate becomes a suitable amount for stirring the electrolytic solution. Therefore, the stratification of the electrolytic solution is further suppressed.

  When the content of iron contained in the positive electrode active material in the fully charged state of the lead storage battery is less than 3.5 ppm, the amount of gas generated on the positive electrode plate decreases, and thus the electrolyte is not sufficiently stirred. In addition, the electrolyte may be easily stratified. In addition, iron and stainless steel manufacturing devices are often used in the manufacturing process of lead-acid batteries. Since iron derived from these devices is mixed in, the iron contained in the positive electrode active material in the fully charged state of the lead-acid battery is used. It is difficult to make the content less than 3.5 ppm.

  For example, a mixer for mixing lead powder, which is a material of the paste of the positive electrode active material, with water or sulfuric acid, a hopper for supplying the material to the mixer, and the like are often formed of acid-resistant stainless steel. Therefore, in order to make the content of iron contained in the positive electrode active material in the fully charged state of the lead storage battery less than 3.5 ppm, the manufacturing apparatus used in the manufacturing process of the lead storage battery is formed of non-ferrous metal or ceramics. Or an additional step of removing iron is required, which leads to an increase in the manufacturing cost of the lead storage battery.

  On the other hand, when the content of iron contained in the positive electrode active material in the fully charged state of the lead storage battery exceeds 20.0 ppm, electrolysis of the electrolytic solution is promoted, and gas such as oxygen gas generated on the positive electrode plate is accelerated. Therefore, the amount of electrolyte decreases, the amount of electrolyte solution decreases, the life of the lead storage battery is shortened, and the internal resistance of the lead storage battery may increase. Furthermore, since self-discharge is promoted, the amount of voltage drop may increase.

  The iron present in the lead-acid battery repeatedly moves through the electrolytic solution to the positive electrode during charging and to the negative electrode during discharging via the electrolyte (shuttle effect). Therefore, the gas generating effect of iron is not limited to the positive electrode. , Also occur in the negative electrode. Therefore, when the separator has a bag shape, the same effect of stirring the electrolyte can be expected regardless of whether the positive electrode plate or the negative electrode plate is housed in the bag-shaped separator. The degree increases.

[Thickness ratio]
As described above, the cause of the bending of the electrode plate is a difference in the thickness of the active material layers formed on both surfaces of the electrode plate. Therefore, in order to make the flatness of the positive electrode plate after chemical formation 4.0 mm or less, the positive electrode after chemical formation with respect to the thickness of the active material layer of the positive electrode active material formed on one plate surface of the positive electrode plate after chemical formation It is preferable that the ratio of the thickness of the active material layer of the positive electrode active material formed on the other plate surface of the plate (hereinafter, also referred to as “thickness ratio”) be 0.67 or more and 1.33 or less. .

  Note that, in order to make the thickness ratio of the active material layer of the positive electrode active material after chemical formation 0.67 or more and 1.33 or less, the thickness ratio of the active material layer of the positive electrode active material before chemical formation is 0.67 or more. The formation may be performed at 1.33 or less. Even if the volume of the positive electrode active material changes during the formation of the positive electrode plate, the thick coating degree ratio does not change before and after the chemical formation as long as the formation conditions of both surfaces of the positive electrode plate are the same.

  If the thickness ratio of the positive electrode plate after chemical formation is within the above numerical range, it is easy to make the flatness of the positive electrode plate after chemical formation 4.0 mm or less. As a result, the gas is easily discharged to the outside of the electrode group, so that an increase in the internal resistance of the lead storage battery is suppressed, and the charged state and the deterioration state can be accurately determined by a method of measuring the internal resistance. .

  The thickness of the active material layer of the positive electrode active material is a distance between the surface of the positive electrode plate and the plate surface of the positive electrode substrate facing the positive electrode plate, that is, a virtual straight line orthogonal to the surface of the positive electrode plate. , The length from the surface of the positive electrode plate to the plate surface of the positive electrode substrate. The surface of the positive electrode plate is a single flat surface in which steps, bends, curvatures, and the like do not substantially exist on a macro scale (about several tens μm to several mm). The thickness of the active material layer of the positive electrode active material may be a value obtained by measuring the distance between the surface of the positive electrode plate and the plate surface of the positive electrode substrate at one place, or the surface of the positive electrode plate and the plate surface of the positive electrode substrate. May be the average of the values obtained by measuring the distances between a plurality of points.

  For example, when a plate-like lattice is used as the positive electrode substrate, the surface of the positive electrode plate and the surfaces of the vertical and horizontal lattice bones forming the lattice mesh of the plate-like lattice oppose each other. The distance from the surface of the bone may be measured, and the measured value may be used as the thickness of the active material layer of the positive electrode active material. In addition, since a plurality of lattice bones are arranged in the plate-like lattice body, the distance between the surface of the positive electrode plate and the surface of the lattice bone is measured in the plurality of lattice bones, and the average of the measured values is used as the positive electrode active material. May be the thickness of the active material layer.

  Also, since the cross-sectional shape of the lattice bone of the plate-shaped lattice body (the cross-sectional shape when cut along a plane perpendicular to the longitudinal direction of the lattice bone) is basically rectangular, the surface of the positive electrode plate faces the surface thereof. Parallel to the surface of the lattice bone. However, in the case of a plate-like lattice manufactured by the expanding method, the plate-like lattice may be twisted or distorted during the manufacturing process. If the plate-like lattice body is twisted or distorted, the surface of the lattice bone is inclined or curved with respect to the surface of the positive electrode plate. Is non-parallel. In such a case, since the distance between the surface of the positive electrode plate and the surface of the lattice plate varies greatly depending on the measurement location, the shortest distance between the surface of the lattice plate and the surface of the positive electrode plate is measured for each lattice bone. The average of the measured values may be defined as the thickness of the active material layer of the positive electrode active material.

  The thick coating degree ratio in the present invention is defined as the thickness of the active material layer of the positive electrode active material formed on one plate surface of the positive electrode plate after chemical formation, and the thickness of the positive electrode active material formed on the other plate surface of the positive electrode plate after chemical formation. This is the ratio of the thickness of the active material layer of the material, and the thickness of the active material layer of the positive electrode active material on either of the two surfaces of the positive electrode plate may be calculated as a denominator. For example, when the positive electrode plate after formation is placed on a flat surface such that both plate surfaces are perpendicular to the vertical direction and the collecting ears are located on the upper right side, The thickness may be calculated using the thickness of the active material layer of the positive electrode active material on the upper surface side of the plate surface as a denominator and the thickness of the active material layer of the positive electrode active material on the lower surface side as a numerator.

〔Example〕
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
(A) Examination of the influence of flatness of positive electrode plate on increase in internal resistance First, a plate-like lattice made of a Pb-Ca-based or Pb-Ca-Sn-based lead alloy is cast, and A collecting ear was formed at a predetermined position. Next, a lead powder mainly composed of lead monoxide was kneaded with water and dilute sulfuric acid, and if necessary, additives were mixed and kneaded to produce a paste of a positive electrode active material. Similarly, a lead of a negative electrode active material was manufactured by kneading lead powder mainly composed of lead monoxide with water and dilute sulfuric acid, further mixing and kneading additives as necessary.

  After filling the plate-like lattice with the paste of the positive electrode active material, aging and drying are performed, and further, chemical formation is performed in a chemical conversion tank, so that the active material of the positive electrode active material containing lead dioxide is formed on both plate surfaces of the electrode plate. A ready-to-use (formulated) positive electrode plate having a material layer formed thereon was obtained. Similarly, after filling the paste of the negative electrode active material into the plate-like lattice, aging and drying, and further performed a chemical conversion in a chemical conversion tank, the negative electrode active material containing metal lead on both plate surfaces of the electrode plate A ready-to-use (formulated) negative electrode plate having an active material layer formed thereon was obtained. The flatness of the positive electrode plate was measured by the method described below.

  A plurality of positive electrode plates and negative electrode plates manufactured as described above were alternately laminated with a separator made of a porous synthetic resin interposed therebetween to prepare an electrode plate group. This electrode plate group was housed in a battery case, and the current collecting ears of each positive electrode plate were connected by a positive electrode strap, and the current collecting ears of each negative electrode plate were connected by a negative electrode strap. The positive strap was connected to one end of the positive terminal, and the negative strap was connected to one end of the negative terminal.

Further, the opening of the battery case was closed with a lid. The positive electrode terminal and the negative electrode terminal passed through the lid, and the other end of the positive electrode terminal and the other end of the negative electrode terminal were exposed to the outside of the lead-acid battery. An electrolyte was injected from a liquid inlet formed in the lid, and the liquid inlet was sealed with a stopper to obtain a lead storage battery.
The battery size was M-42, the number of positive electrode plates constituting the electrode plate group was 6, and the number of negative electrode plates was 7. The positive electrode plate and the negative electrode plate were manufactured by a continuous manufacturing method. The flatness of the positive electrode plate after chemical formation was adjusted by changing the thick coating ratio of the active material layer of the positive electrode active material formed on both surfaces of the positive electrode plate before chemical formation.

Further, the thickness of the separator was adjusted such that a predetermined group pressure was applied to the electrode plate group. The density of the positive electrode active material of the positive electrode plate is 4.4 g / cm ³ . The ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide contained in the positive electrode active material is 30%. The average diameter of the pores of the positive electrode active material is 0.10 μm, and the porosity of the positive electrode active material is 30%. The surface roughness Ra of the surface of the positive electrode plate is 0.10 mm. The distance between the adjacent positive and negative electrode plates is 0.60 mm. The electrolyte used contained aluminum sulfate at a concentration of 0.1 mol / L.

Next, after performing initial charging on the produced lead storage battery, aging was performed for 48 hours. Then, the internal resistance of the lead storage battery was measured. The measured value of the internal resistance was defined as an “initial value”.
Subsequently, constant voltage charging was performed on the fully charged lead storage battery after aging, and the internal resistance was measured immediately after the constant voltage charging was completed. This measured value of the internal resistance was defined as “the value immediately after charging”. The conditions for constant voltage charging are a maximum current of 100 A, a control voltage of 14.0 V, and a charging time of 10 minutes (the lead-acid battery has a 5-hour rate capacity (rated capacity) of 32 Ah).
When the constant voltage charging was completed, the battery was allowed to stand for 1 hour, and the internal resistance after the standing was measured. The measured value of the internal resistance was defined as “the value after standing”.

  The flatness of the positive electrode plate was measured as follows. First, the thickness is measured at a plurality of locations on the positive electrode plate using a micrometer, and the average value is defined as the thickness of the positive electrode plate. Next, as shown in FIG. 2, the positive electrode is placed on the flat surface of the base such that the plate surface of the positive electrode plate and the flat surface of the base are substantially parallel to each other, and the convex surface of the curved positive electrode plate faces upward. The plate is placed, and the distance h between the vertex of the convex surface of the curved positive electrode plate and the plane of the base is measured using a height gauge. Then, a value obtained by subtracting the thickness of the positive electrode plate from the distance h is defined as flatness.

  Table 1 shows the results. Using the initial value of the internal resistance, the value immediately after charging, and the value after standing, the rise rate of the internal resistance was calculated. The rate of increase of the value immediately after charging with respect to the initial value is calculated by ([value immediately after charging]-[initial value]) / [initial value], and the rate of increase of the value after standing still relative to the initial value is ([static [Initial value] / [initial value]) / [initial value].

The condition A that the rate of increase in the value immediately after charging with respect to the initial value is 10% or less, and the rate of increase in the value after standing still with respect to the initial value is 5% or less, or On the other hand, when both the condition B that the rate of increase in the value after standing still is a value lower by 4% or more is satisfied, it is determined that the increase in the internal resistance is significantly suppressed, and in Table 1, it is determined by a circle. Indicated.
When only one of the conditions A and B is satisfied, it is determined that the increase in the internal resistance is sufficiently suppressed, but it cannot be said that it is notably suppressed. Indicated by the mark. When neither of the conditions A and B is satisfied, it is determined that the suppression of the increase in the internal resistance is slightly insufficient or completely insufficient, and is indicated by a cross in Table 1.

From the results shown in Table 1, it can be seen that in Examples 1 to 4 in which the flatness of the positive electrode plate was 4.0 mm or less, the increase in internal resistance was significantly suppressed.
On the other hand, in Comparative Example 1 in which the flatness of the positive electrode plate is 5.0 mm, it can be seen that the rate of increase in the value immediately after charging with respect to the initial value is high. In addition, since the rate of increase of the value after standing still with respect to the initial value is high, it can be seen that the rate of decrease of the internal resistance is slow.

(B) Examination of the influence of group pressure on the increase in internal resistance Next, the effect of group pressure applied to the electrode plate group was examined. The configuration, manufacturing method, and evaluation method of the lead storage battery are the same as those in the case of the above (A) except that the thickness of the separator is adjusted so that a predetermined group pressure is applied to the electrode plate group. The same is true. The evaluation results are shown in Table 2.

  From the evaluation results shown in Table 2, even when the flatness of the positive electrode plate is 4.0 mm or less, when the group pressure is 20 kPa, the rate of increase in the value after standing still relative to the initial value is high, and the rate of decrease in internal resistance is high. Is slightly slower. This is considered to be due to the fact that gas is difficult to be discharged from the electrode plate group because the group pressure is high. From these results, it can be seen that the group pressure applied to the electrode plate group is preferably set to 10 kPa or less in order for the internal resistance increased by the constant voltage charging to quickly return to the initial value.

(C) Examination of influence of density of positive electrode active material on performance of lead storage battery The influence of density of positive electrode active material was examined. Except for the difference in the density of the positive electrode active material, the configuration and manufacturing method of the lead storage battery are the same as in the case of the above-described study (A), unless otherwise specified. Regarding the performance of the lead storage battery, the increase in the internal resistance was evaluated in the same manner as in the above-mentioned study (A), and the stratification of the electrolyte and the battery life were also evaluated.

  The stratification of the electrolyte and the battery life were evaluated by a 17.5% DOD life test described in EN 50342-6: 2015 of the European standard (EN standard). That is, the following operations (1), (2), and (3) are repeated for a plurality of cycles, and when the voltage reaches 10 V, it is determined that the battery has reached the end of its life. The difference in specific gravity between the upper part and the lower part of the liquid was measured.

(1) Adjust the state of charge (SOC) to 50%.
(2) Charge and discharge at a depth of discharge (DOD) of 17.5% is repeated 85 times.
(3) Full charge and conduct 20HR capacity test. After the capacity test is completed, perform a full charge again.

  The evaluation results are shown in Tables 3 and 4. When both the condition C that the battery life is 800 cycles or more and the condition D that the stratification of the electrolytic solution (difference in specific gravity between the upper and lower portions of the electrolytic solution) is 0.03 or less are satisfied, the lead storage battery Was judged to be remarkably excellent, and in Table 4, it was indicated by a mark. When only one of the conditions C and D is satisfied, it is determined that the performance of the lead-acid battery is sufficiently excellent but not remarkably excellent. Indicated. When neither condition C nor condition D was satisfied, it was determined that the performance of the lead storage battery was slightly insufficient or completely insufficient.

From the evaluation results shown in Tables 3 and 4, when the density of the positive electrode active material is 4.2 g / cm ³ or more and 4.6 g / cm ³ or less, the increase in internal resistance is significantly suppressed and the decrease in internal resistance is reduced. It turns out that the speed is fast. Further, it can be seen that the battery life of the lead storage battery is excellent, and the stratification of the electrolyte does not easily occur.

(D) Investigation on the effect of αβ ratio of lead dioxide on the performance of lead storage battery Investigation on the effect of the ratio α / (α + β) of the mass α of α-lead dioxide and the mass β of β-lead dioxide contained in the positive electrode active material did. The configuration and manufacturing method of the lead storage battery are the same as in the case of the above-described study (A), unless otherwise specified, except that the αβ ratio of lead dioxide is different. Regarding the performance of the lead storage battery, an increase in internal resistance was evaluated as in the case of the above (A), and the stratification of the electrolytic solution and the battery life were also evaluated as in the case of the above (C).

  Tables 5 and 6 show the evaluation results. From the evaluation results shown in Tables 5 and 6, when the αβ ratio α / (α + β) of lead dioxide is 20% or more and 40% or less, the increase in internal resistance is sufficiently suppressed and the rate of decrease in internal resistance is fast. You can see that. Further, it can be seen that the battery life of the lead storage battery is excellent, and the stratification of the electrolyte does not easily occur.

(E) Investigation of the influence of the average diameter of the pores of the positive electrode active material and the porosity of the positive electrode active material on the performance of the lead storage battery The influence of the average diameter of the pores of the positive electrode active material and the porosity of the positive electrode active material investigated. The configuration and manufacturing method of the lead-acid battery are the same as in the case of the above (A) unless otherwise specified, except that the average diameter of the pores of the positive electrode active material or the porosity of the positive electrode active material is different. It is. Regarding the performance of the lead storage battery, the increase in the internal resistance was evaluated in the same manner as in the above-mentioned study (A), and the utilization rate of the active material was also evaluated.

The utilization rate of the active material was determined by measuring a discharge capacity after performing a 5-hour rate discharge test.
The evaluation results are shown in Tables 7, 8, 9, and 10. Regarding the utilization rate, when the measured value of the discharge capacity was 32 Ah or more, which is the rated capacity of M-42, it was judged that the utilization rate was remarkably excellent. Was. When the measured value of the discharge capacity is 30 Ah or more and less than 32 Ah, it is determined that the utilization factor is sufficiently excellent, but cannot be said to be remarkably excellent. Was. When the measured value of the discharge capacity was less than 30 Ah, it was determined that the utilization rate was slightly insufficient or completely insufficient.

  From the evaluation results shown in Tables 7, 8, 9, and 10, the average diameter of the pores of the positive electrode active material is 0.07 μm or more and 0.20 μm or less, or the porosity of the positive electrode active material is 30% or more and 50% or less. In the case of, it can be seen that the rise of the internal resistance is remarkably suppressed and the rate of decrease of the internal resistance is fast. Further, it can be seen that the utilization rate of the active material is remarkably excellent.

(F) Investigation on the effect of surface roughness Ra on the surface of the positive electrode plate on the increase in internal resistance The effect of surface roughness Ra on the surface of the positive electrode plate was examined. The configuration, manufacturing method, and evaluation method of the lead storage battery are the same as in the case of the above-described study (A), unless otherwise specified, except that the surface roughness Ra of the surface of the positive electrode plate is different. Table 11 shows the evaluation results.
From the evaluation results shown in Table 11, it can be seen that when the surface roughness Ra of the surface of the positive electrode plate is 0.20 mm or less, the increase in internal resistance is remarkably suppressed and the rate of decrease in internal resistance is fast.

(G) Examination of the influence of the distance between the positive electrode plate and the negative electrode plate on the increase in the internal resistance The distance between the adjacent positive electrode plate and the negative electrode plate (hereinafter sometimes referred to as “inter-electrode plate distance”) The effects were discussed. The configuration, manufacturing method, and evaluation method of the lead storage battery are the same as in the case of the above-described study (A), unless otherwise specified, except that the distance between the electrode plates is different. Table 12 shows the evaluation results.
From the evaluation results shown in Table 12, it is found that when the distance between the electrode plates is 0.60 mm or more and 0.90 mm or less, the increase in internal resistance is significantly suppressed and the rate of decrease in internal resistance is fast.

(H) Investigation on the effect of the concentration of aluminum ions in the electrolytic solution on the increase in internal resistance and charge acceptability The effect of the concentration of aluminum ions in the electrolytic solution was examined. The configuration and manufacturing method of the lead storage battery are the same as in the case of the above-described study (A), unless otherwise specified, except that the concentration of aluminum ions in the electrolytic solution is different. Regarding the performance of the lead storage battery, the increase in internal resistance was evaluated in the same manner as in the above-mentioned study (A), and the charge acceptability was also evaluated.

  The charge acceptability was evaluated as follows. The lead storage battery was fully charged, and after confirming that the temperature of the electrolytic solution was in the range of 23 ° C. or more and 27 ° C. or less, the battery was discharged at a 5-hour rate current for 0.5 hour. Next, the lead storage battery is allowed to stand at a temperature of 23 ° C. or more and 27 ° C. or less for 20 hours, and after confirming that the temperature of the electrolytic solution is in a range of 23 ° C. or more and 27 ° C. or less, the temperature of 23 ° C. or more and 27 ° C or less Constant voltage charging was performed at a temperature of 13.9 V to 14.1 V and a maximum current of 100 A, and the charging current was measured 5 seconds after the start of charging.

  Table 13 shows the evaluation results. Regarding the evaluation results of the charge acceptability, when the charging current is higher than the reference example in which the concentration of aluminum ions in the electrolytic solution is 0 mol / L by 10 A or more, it is indicated by a circle in Table 13 and exceeds 0 A. If it is higher than 10 A, it is indicated by a triangle in Table 13. In addition, in the case where the charging current is the same value as that of the reference example or lower than that of the reference example, it is indicated by a cross in Table 13.

  Furthermore, the overall judgment was made based on the evaluation results of the increase rate of the internal resistance and the charge acceptability. Table 13 shows the results. In Table 13, when both the rate of increase of the internal resistance and the charge acceptability were judged as ○, the comprehensive judgment showed a mark ○, and at least one of the rate of increase of the internal resistance and the charge acceptability was marked with a △. Or, in the case of the judgment of x mark, the comprehensive judgment shows x mark.

It is known that the addition of aluminum ions to an electrolytic solution improves charge acceptability. However, in a lead-acid battery using an electrode plate with a large flatness, when aluminum ions are added to the electrolyte, gas is accumulated between the plates due to the increase in the flatness, and the internal resistance increases. It was found that the effect of the addition of the compound became small.
In addition, it was found that when aluminum ions or sodium ions were excessively added to the electrolytic solution, the resistance and viscosity of the electrolytic solution increased, so that the gas became difficult to escape, and the internal resistance was more likely to increase. Therefore, it is important to make the concentration of aluminum ions and sodium ions in the electrolytic solution appropriate as well as the flatness.

(I) Investigation on the effect of the concentration of sodium ion in the electrolytic solution on the increase in internal resistance and charge acceptability The effect of the concentration of sodium ion in the electrolytic solution was examined. The configuration and manufacturing method of the lead storage battery are the same as in the case of the above-described study (H), unless otherwise specified, except that the concentrations of aluminum ions and sodium ions in the electrolyte solution are different. Regarding the performance of the lead storage battery, the increase in the internal resistance and the charge acceptability were evaluated as in the case of the above (H), and the battery life was also evaluated as in the case of the above (C).

Table 14 shows the evaluation results. The battery life evaluation results are indicated by a circle in Table 14 when the battery life is 800 cycles or more, and are indicated by a cross in Table 14 when the battery life is less than 800 cycles.
Furthermore, comprehensive evaluation was performed by comprehensively evaluating the rate of increase of the internal resistance, the charge acceptability, and the battery life. Table 14 shows the results. In Table 14, when all of the increase rate of the internal resistance, the charge acceptability, and the battery life were judged to be ○, the comprehensive judgment showed the mark 、, and the increase rate of the internal resistance, the charge acceptability, and the battery life If at least one of them is a judgment of a mark or a mark x, the comprehensive judgment indicates a mark of x.

It was found that the presence of sodium ions in the electrolyte was harmful and hindered the effect of improving the charging rate by aluminum ions and the like. The concentration of sodium ions in the electrolyte is preferably from 0.002 mol / L to 0.05 mol / L.
Since lignin used as an additive for the negative electrode is generally a sodium salt, if the concentration of sodium ions is less than 0.002 mol / L, the amount of lignin added will be reduced. The service life will be shortened.

Reference Signs 1 electrode plate group 10 positive electrode plate 20 negative electrode plate 30 separator

Claims (5)

  A positive electrode plate having a positive electrode active material containing lead dioxide, and a negative electrode plate having a negative electrode active material containing metal lead, comprising a plurality of electrode plates stacked alternately via a separator, the electrode plate group Is immersed in an electrolytic solution, the flatness of the positive electrode plate after formation is 4.0 mm or less, and the distance between the adjacent positive electrode plate and the negative electrode plate is 0.60 mm or more and 0.90 mm or less. Some lead-acid batteries.   2. The lead-acid battery according to claim 1, wherein the positive electrode plate after formation is curved in a substantially bowl shape, and a vertex of a convex surface of the curved positive electrode plate is located at a lower portion than a vertical center of the positive electrode plate. 3. . ^3. The lead-acid battery according to claim 1, wherein the positive electrode active material has a density of 4.2 g / cm ³ or more and 4.6 g / cm ³ or less. 4.   The lead storage battery according to any one of claims 1 to 3, wherein the content of aluminum ions in the electrolytic solution is from 0.01 mol / L to 0.3 mol / L.   The lead storage battery according to any one of claims 1 to 4, wherein a group pressure applied to the electrode plate group is 10 kPa or less.

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