lead-acid batteries

Abstract

To provide a lead storage battery capable of suppressing reduction of HR discharge performance while securing high capacity.SOLUTION: A lead storage battery 1 includes at least one cell including an electrode plate group 11 and an electrolyte. The electrode plate group includes a cathode plate 3 containing a cathode electrode material, an anode plate 2 containing an anode electrode material, and a separator 4 interposed between the cathode plate and the anode plate. A ratio of a density Dn of the anode electrode material with respect to a density Dp of the cathode electrode material: Dn / Dp satisfies Dn / Dp≥1.05. A total sum S (cm2) of areas of portions of the cathode plate opposed with the anode plate in the electrode plate group, an average value dt (cm) of distances between the cathode plates and the anode plates which are adjacent, and a capacity Vc of the electrode plate group Vc (cm-3) satisfy 55(cm-2)≤S / (dt Vc)≤82(cm-2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lead-acid battery. [Background technology]

[0002] Lead-acid batteries are used in a variety of applications, including automotive and industrial applications. Lead-acid batteries include negative and positive plates, a separator (or mat), and an electrolyte. Each plate includes a current collector and an electrode material. Various attempts have been made to improve the performance of lead-acid batteries.

[0003] Patent Document 1 proposes a lead-acid battery in which a plurality of positive electrode plates each having an active material containing lead dioxide in a grid made of a lead alloy and negative electrode plates each having an active material containing metallic lead in a grid made of a lead alloy are alternately stacked with a bag-shaped separator interposed between them, the plate assembly being housed in a battery case and immersed in a dilute sulfuric acid-based electrolyte, the electrolyte containing Al ions from 0.02 mol / L to 0.2 mol / L, and the average distance between the positive and negative electrode plates in the plate assembly being from 0.5 mm to 0.8 mm.

[0004] Patent Document 2 discloses a battery comprising a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the electrolyte contains 0.03 to 0.3 mol / L of Na and / or 0.02 to 0.2 mol / L of Al, and the separator has a first rib on the side of the negative electrode plate, and where h (mm) is the height that the first rib protrudes from the main surface of the separator and U (%) is the utilization rate of the electrolyte, Q=U / (h 1 / 2 We have proposed a lead-acid battery with a rib parameter Q of 300 or less.

[0005] Patent Document 3 describes a positive and negative electrode grid formed from a lead alloy containing no antimony, a negative electrode active material having a weight greater than that of a positive electrode active material, and a packing density of the negative electrode active material of 5 to 6 g / cm. 3 and a negative electrode plate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-4974 [Patent Document 2] International Publication No. 2019 / 087686 [Patent Document 3] Japanese Patent Application Laid-Open No. 61-165956 Summary of the Invention [Problem to be solved by the invention]

[0007] As the performance of devices equipped with lead-acid batteries improves, even higher performance is required of lead-acid batteries. One of the typical applications of lead-acid batteries is in automobiles. Lead-acid batteries used in automobiles require, for example, excellent starting performance, a large capacity that can accommodate various loads, and high-rate discharge performance that enables high-current discharge. However, the volume of a battery case is limited, and if the number of plates is increased to ensure high high-rate discharge performance, the electrode material must be reduced to fit within the battery case, resulting in a decrease in capacity. Thus, there is a trade-off between high high-rate discharge performance and high capacity, and it is difficult to improve both at the same time. Hereinafter, high-rate discharge performance may be simply referred to as HR discharge performance. [Means for solving the problem]

[0008] One aspect of the present invention is a lead-acid battery, The lead-acid battery includes at least one cell including a plate pack and an electrolyte; the electrode plate group includes positive electrode plates including a positive electrode material, negative electrode plates including a negative electrode material, and a separator interposed between the positive electrode plates and the negative electrode plates; a ratio Dn / Dp of a density Dn of the negative electrode material to a density Dp of the positive electrode material satisfies Dn / Dp≧1.05; The sum of the areas of the positive electrode plates facing the negative electrode plates in the electrode plate group S (cm 2 ), the average value dt (cm) of the distance between the adjacent positive and negative plates, and the volume Vc (cm -3 ) is 55 (cm -2 )≦S / (dt·Vc)≦82(cm -2 ) relates to a lead-acid battery that satisfies the above requirements. [Effects of the Invention]

[0009] In lead-acid batteries, this technology can suppress the decline in HR discharge performance while ensuring high capacity. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a partially cutaway exploded perspective view showing the appearance and internal structure of a lead-acid battery according to one aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] It is generally believed that HR discharge performance is affected by, for example, the area of the portion of the positive electrode plate facing the negative electrode plate in the electrode plate assembly or the distance between adjacent positive and negative electrode plates. Specifically, it has been conventionally believed that the HR discharge performance tends to improve as the area of the portion of the positive electrode plate facing the negative electrode plate increases or the distance between adjacent positive and negative electrode plates decreases.

[0012] For example, the total area S (unit: cm) of the positive electrode plate facing the negative electrode plate in the electrode plate group 2 ) to the average distance dt (unit: cm) between adjacent positive and negative plates: S / dt is calculated as the volume Vc (unit: cm 3 ) standardized parameter: S / (dt·Vc) (unit: cm -2) is thought to have a significant effect on HR discharge performance. For example, an increase in S / (dt·Vc) means that the total opposing area between the plates, S, increases, or the distance dt between adjacent plates decreases. Therefore, it is expected that the HR discharge performance tends to improve as S / (dt·Vc) increases. However, this tendency is not related to the density Dn (unit: g / cm) of the negative electrode material. 3 ) and the density Dp (unit: g / cm 3 It was found that this effect may not be observed depending on the value of the ratio Dn / Dp to the capacitance of the battery. More specifically, it was found that depending on the value of the Dn / Dp ratio, if S / (dt·Vc) becomes too large, the HR discharge performance may deteriorate.

[0013] More specifically, when the Dn / Dp ratio satisfies Dn / Dp < 1.05, the HR discharge performance remains almost constant even when S / (dt · Vc) increases. Furthermore, the initial discharge capacity remains almost constant even when S / (dt · Vc) increases. In contrast, when the Dn / Dp ratio satisfies Dn / Dp ≥ 1.05, the HR discharge performance improves up to a certain S / (dt · Vc) value. However, contrary to expectations, it was revealed that the HR discharge performance deteriorates when S / (dt · Vc) exceeds a certain value.

[0014] In view of the above, a lead-acid battery according to one aspect of the present invention includes at least one cell containing an electrode plate assembly and an electrolyte. The electrode plate assembly includes a positive electrode plate containing a positive electrode material, a negative electrode plate containing a negative electrode material, and a separator interposed between the positive electrode plate and the negative electrode plate. The ratio of the density Dn of the negative electrode material to the density Dp of the positive electrode material: Dn / Dp satisfies Dn / Dp≧1.05. The sum of the areas S (cm) of the portions of the positive electrode plates facing the negative electrode plates in the electrode plate assembly is 2 ), the average distance dt (cm) between adjacent positive and negative plates, and the volume Vc (cm 3 ) is 55 (cm -2 )≦S / (dt·Vc)≦82(cm -2 ) is satisfied. When Dn / Dp≧1.05, 55(cm -2)≦S / (dt·Vc)≦82(cm -2 ), high HR discharge performance can be ensured. Hereinafter, the area of the portion of the positive electrode plate facing the negative electrode plate, the total area S of this portion, and the average distance dt between adjacent positive and negative electrode plates may be simply referred to as the "facing area between the plates," the "total S" (or "total facing area S"), and the "distance dt between the plates," respectively.

[0015] When Dn / Dp satisfies Dn / Dp<1.05, the HR discharge performance tends to improve slightly as S / (dt·Vc) increases, but the improvement is small. -2 Even when the temperature exceeds 1000 K, a relatively high HR discharge performance is maintained.

[0016] When Dn / Dp satisfies Dn / Dp ≥ 1.05, HR discharge performance tends to improve as S / (dt·Vc) increases. This improvement is greater than when Dn / Dp < 1.05. This improvement in HR discharge performance is thought to be due to the fact that as S / (dt·Vc) increases, the resistance between the plates decreases, and as Dn / Dp increases, the conductivity of the negative plate improves. However, once S / (dt·Vc) becomes large enough, HR discharge performance begins to gradually decline, reaching 82cm -2 It was revealed that the HR discharge performance significantly deteriorates when Dn / Dp exceeds 1.05. This deterioration in HR discharge performance is not observed when Dn / Dp<1.05. In other words, when S / (dt·Vc) is a relatively large value, the behavior of HR discharge performance differs significantly between when Dn / Dp<1.05 and when Dn / Dp≧1.05. This difference in behavior was not previously known.

[0017] This difference in behavior is thought to be due to the influence of not only the resistance between the plates and the conductivity of the negative plate, but also the state of the electrolyte on HR discharge performance. More specifically, when S / (dt·Vc) becomes large (e.g., when the total opposing surface area between the plates, S, increases or the distance between the plates, dt, decreases), the amount of electrolyte near the plates decreases relative to when S / (dt·Vc) is small. Furthermore, when Dn / Dp is large (Dn / Dp ≥ 1.05), the amount of electrolyte inside the negative plate decreases relative to when Dn / Dp is small. In this situation where there is little electrolyte inside and near the negative plate, the movement of ions in the electrolyte becomes the rate-limiting step of the discharge reaction, making it difficult for the discharge reaction to proceed. HR discharge performance is highly dependent on the reaction near the negative plate. When Dn / Dp<1.05, a certain amount of electrolyte is retained inside and near the negative electrode plate due to the balance of electrolyte within the battery, compared to when Dn / Dp≧1.05. Therefore, the HR discharge performance is hardly affected by the electrolyte migration rate.

[0018] Also, when Dn / Dp<1.05, S / (dt·Vc) is 55cm -2 Even if the value is less than 55cm, a certain level of high HR discharge performance can be obtained. -2 On the other hand, when Dn / Dp≧1.05, the improvement effect of HR discharge performance is not so large. -2 By doing more than 55cm -2 The HR discharge performance is significantly improved compared to when the distance between the electrodes is less than 55(cm). By reducing the distance dt between the electrodes, the resistance between the electrodes decreases, and the ion migration speed increases. In addition, by increasing the total surface area S between the electrodes, the area in which the discharge reaction occurs in the electrodes increases compared to when the total surface area S is small. It is believed that these occur when the conductivity of the negative electrode plate is increased by Dn / Dp ≥ 1.05, resulting in a significant improvement in the HR discharge performance as described above. When Dn / Dp ≥ 1.05, the HR discharge performance is significantly improved compared to when the distance between the electrodes is less than 55(cm). -2 )≦S / (dt·Vc)≦82(cm -2) has not been known to ensure high HR discharge performance.

[0019] Furthermore, when Dn / Dp is 1.05 or more, the density of the negative electrode material is relatively higher than when Dn / Dp is small, and the conductivity of the negative electrode plate is increased. At the same time, the density of the positive electrode material is relatively lower, and the utilization rate of the positive electrode is increased. -2 )≦S / (dt·Vc)≦82(cm -2 ), the surface area of the positive electrode plate that comes into contact with the electrolyte is relatively large, which improves the utilization rate per unit volume of the positive electrode material, thereby ensuring high capacity.

[0020] From the viewpoint of obtaining higher HR discharge performance while maintaining high capacity, 58(cm -2 It is preferable to satisfy the condition S / (dt·Vc)≦S / (dt·Vc). In this case, particularly when Dn / Dp≧1.05, a significant improvement in HR discharge performance is obtained compared to when Dn / Dp<1.05. Furthermore, when S / (dt·Vc) is in this range, each parameter is optimized, making it easier to stably obtain high capacity.

[0021] S / (dt·Vc)≦80(cm -2 ) is satisfied, there is almost no decrease in HR discharge performance even when S / (dt·Vc) increases, and higher HR discharge performance can be ensured. Furthermore, higher HR discharge performance can be obtained when Dn / Dp≧1.05 compared to when Dn / Dp<1.05. Furthermore, if S / (dt·Vc) is in this range, each parameter is optimized, making it easier to obtain a stable high capacity.

[0022] The density Dn of the negative electrode material and the density Dp of the positive electrode material are the bulk densities (unit: g / cm 3 The bulk density is calculated by dividing the mass (unit: g) of the electrode material by the bulk volume (unit: cm 3) The bulk volume is determined by mercury intrusion porosimetry. The bulk density is determined for a sample of uncrushed electrode material taken from an electrode plate removed from a lead-acid battery. The uncrushed sample is taken from near the center of the electrode plate in the surface direction.

[0023] The negative electrode material and the positive electrode material are usually held by a current collector. The electrode material is the portion of the electrode plate excluding the current collector. A mat, pasting paper, or other member may be attached to the electrode plate. Such members (also called attachment members) are used integrally with the electrode plate and are therefore included in the electrode plate. When the electrode plate includes an attachment member (such as a mat or pasting paper), the electrode material is the portion of the electrode plate excluding the current collector and attachment member.

[0024] The total area of the opposing electrodes S (unit: cm 2 ) is the area (cm2) of the part of all the positive plates in one electrode group that faces the adjacent negative plate. 2 ) The area of the portion of the positive electrode plate facing the negative electrode plate is the area of the overlapping portion of the projections of the portion of the positive electrode plate where the positive electrode material is present and the portion of the negative electrode plate where the negative electrode material is present, projected in the thickness direction of the electrode plate. The area of the portion of the positive electrode plate facing the negative electrode plate is the same as the area of the portion of the negative electrode plate facing the positive electrode plate.

[0025] The distance between the electrodes dt (unit: cm) can be calculated using the following formula. dt=[Lc-(Te+Ts)] / (n-1) Here, Lc is the internal dimension (unit: cm) of the cell chamber in the direction parallel to the stacking direction of the plates in the electrode assembly. Lc is the shortest distance between opposing wall surfaces of the cell chamber in the direction parallel to the stacking direction of the plates. Here, the shortest distance between the wall surfaces is measured at a position where the wall surface faces the electrode assembly. If a spacer or the like is disposed between at least one of the cell chamber wall surfaces and the electrode assembly in the direction parallel to the stacking direction of the plates, the internal dimension Lc of the cell chamber is the shortest distance between the opposing spacers or between the opposing cell chamber wall surfaces and the spacer at a position facing the electrode assembly. If the lead-acid battery case is not divided into multiple cell chambers and the electrode assembly is housed in a single case, Lc is the internal dimension of the case in the above direction. In this case, the internal dimensions of the battery case are the shortest distance between the opposing wall surfaces of the battery case (or, if spacers are present between the battery case and the plate group, between the opposing spacers or between the opposing wall surfaces of the battery case and the spacers), in a direction parallel to the stacking direction of the plates, as in the case of the cell chamber, at a position facing the plate group.

[0026] Te is the total thickness (unit: cm) of all the plates included in the plate assembly.

[0027] Ts is the sum (unit: cm) of the thicknesses of the separators (hereinafter referred to as outermost separators) located further outward than the plates located at both ends of the electrode plates included in the electrode plate assembly. The thickness of the outermost separator basically refers to the total thickness of the outermost separator. If the outermost separator has a base portion and ribs protruding from the base portion, the total thickness is the sum of the thickness of the base portion and the height of the ribs. However, if ribs (hereinafter referred to as outer ribs) are formed on the outer surface of the outermost separator and ribs (hereinafter referred to as wall ribs) are formed on a member in contact with the outermost separator and the height of the wall ribs is higher than the height of the outer ribs, the thickness of the outermost separator used to calculate Ts is the value obtained by subtracting the height of the outer ribs from the total thickness of the outermost separator. Specifically, the member in contact with the outermost separator is the cell chamber (the battery case if the electrode plate assembly is housed in a single battery case) or a spacer. In addition, when outer ribs and wall ribs are formed and the height of the wall ribs is lower than the height of the outer ribs, the value obtained by subtracting the height of the wall ribs from the total thickness of the outermost separator is used as the thickness of the outermost separator for calculating Ts.

[0028] (n-1) is the number of gaps between plates, and n is the total number of plates in the plate group.

[0029] The volume Vc is the average area (unit: cm) of the plates included in the electrode group. 2 ) and the inner dimension Lc (unit: cm) of the cell chamber. Here, the average area of the electrode plates is calculated by dividing the total projected area of all the electrode plates included in the electrode plate group, excluding the lug portions, in the thickness direction, by the total number of electrode plates.

[0030] The electrolyte of a lead-acid battery may contain at least one ion selected from the group consisting of Al ions, Na ions, Li ions, and Mg ions. When the electrolyte contains such ions, crystal growth is less likely to occur when lead ions in the electrolyte are reduced in the negative electrode plate. Therefore, even when the inter-plate distance dt is small, permeation short-circuiting is easily reduced. In particular, in idling stop (also known as start-stop or idle reduction) applications, lead-acid batteries are used in an undercharged state known as a partial state of charge (PSOC), which significantly increases the elution of lead ions and makes permeation short-circuiting more likely. Even in such cases, permeation short-circuiting can be reduced. In this specification, idling stop is sometimes simply referred to as IS. An example of an IS application is a vehicle equipped with an idle reduction system.

[0031] The term "permeating short circuit" refers to a short circuit that occurs when dendrites (for example, dendritic crystals mainly composed of lead) that grow from an electrode penetrate the separator and reach the adjacent electrode.

[0032] In lead-acid batteries, the separator typically includes a base. The base is the sheet-like portion of the separator that defines its outer shape, excluding protrusions such as ribs. A lead-acid battery may also include a mechanism for separating the negative electrode plate from the base. Even when the inter-electrode distance dt is small, the presence of such a mechanism can reduce permeation short circuits. Examples of such mechanisms include ribs that protrude from the base toward the negative electrode plate or a mat interposed between the negative electrode plate and the separator.

[0033] Lead-acid batteries can be either valve-regulated (sealed) or flooded (vented) lead-acid batteries. Valve-regulated lead-acid batteries are sometimes called VRLA (Valve Regulated Lead-Acid Battery).

[0034] In this specification, the up-down direction of a lead-acid battery or its components (such as plates, a battery case, and a separator) refers to the up-down direction in the vertical direction of the lead-acid battery when the battery is in use. Each of the positive and negative plates has a lug for connecting to an external terminal. In some cases, such as horizontally placed valve-regulated lead-acid batteries, the lug is provided on the side of the plate so as to protrude laterally, but in most lead-acid batteries, the lug is usually provided on the top of the plate so as to protrude upward.

[0035] Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described in detail for each of its main components, but the present invention is not limited to the following embodiment.

[0036] [Lead acid battery] (positive electrode plate) A positive electrode plate for a lead-acid battery is, for example, a paste-type positive electrode plate, which includes a positive electrode current collector and a positive electrode material.

[0037] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding and punching. A lattice-shaped current collector is preferably used as the positive electrode current collector because it is easy to support the positive electrode material.

[0038] The positive electrode current collector may be made of pure lead. When the positive electrode current collector is made of a lead alloy, examples of the lead alloy include Pb-Ca alloys, Pb-Sn alloys, and Pb-Ca-Sn alloys. The lead alloy may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, and Cu.

[0039] The positive electrode current collector may have a surface layer. The surface layer and the inner layer of the positive electrode current collector may have different compositions. The surface layer may be formed on a part of the positive electrode current collector. For example, the surface layer may be formed only on the grid portion, the lug portion, or the frame portion of the positive electrode current collector.

[0040] The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) that generates capacity through an oxidation-reduction reaction. The positive electrode material may contain additives (reinforcing materials (e.g., resin fibers)) as needed.

[0041] In a lead-acid battery, the density Dp of the positive electrode material is, for example, 3.7 g / cm 3 or more, 3.75 g / cm 3 The density Dp of the positive electrode material may be, for example, 4.5 g / cm 3 From the viewpoint of easily balancing with the density Dn of the negative electrode material, the density of the positive electrode material is 4.30 g / cm 3 Preferably less than 4.20 g / cm 3 It may be the following:

[0042] The density Dp of the positive electrode material is 3.7 g / cm 3 or more (or 3.75g / cm 3 or more)4.5g / cm 3 Below, 3.7g / cm 3 or more (or 3.75g / cm 3 above)4.30g / cm 3 or less than 3.7g / cm 3 or more (or 3.75g / cm 3 or more)4.20g / cm 3 It may be the following:

[0043] The Dn / Dp ratio is 1.05 or more. The Dn / Dp ratio is, for example, 1.3 or less. From the viewpoint of easily ensuring high durability in IS life performance, the Dn / Dp ratio is preferably 1.2 or less.

[0044] In the electrode group, S / (dt·Vc) is 55cm -2 From the viewpoint of ensuring higher HR discharge performance and stable high capacity, S / (dt·Vc) is 58cm -2 More than 58.5cm is preferable. -2 S / (dt·Vc) is 82cm or more. -2From the viewpoint of ensuring higher HR discharge performance and stable high capacity, S / (dt·Vc) is 80cm -2 or less than 79cm -2 Less than 78.5cm is preferable -2 It may be the following:

[0045] S / (dt·Vc) is 55cm -2 or more (or 58cm -2 above) 82cm -2 Below, 55cm -2 or more (or 58cm -2 over)80cm -2 Below, 55cm -2 or more (or 58cm -2 above) 79cm -2 Below, 55cm -2 or more (or 58cm -2 or more)78.5cm -2 Below, 58.5cm -2 Over 82cm -2 or less (or 80cm -2 or less), or 58.5cm -2 Over 79cm -2 or less (or 78.5cm -2 (See below) may also be used.

[0046] In the electrode plate group, the total opposing area S between the electrode plates is determined according to the desired capacity and size of the lead-acid battery. For example, the total opposing area S is 1000 cm 2 is more than 1200cm 2 More than 1400cm 2 or more than 1500cm 2 The total opposing area S may be, for example, 4000 cm 2 is less than 3000 cm 2 Below, 2000cm 2 or less than 1700cm 2 However, the total facing area S is not limited to this range. 2 More than 2000cm 2 (or 1700cm 2) or less, when Dn / Dp≧1.05, the effect of suppressing the decline in HR discharge performance by setting S / (dt·Vc) in the above range is likely to be significant. In addition, excellent results are likely to be obtained in the overall discharge performance described below. From the same perspective, when the total opposing area S is 1500 cm 2 More than 2000cm 2 (or 1700cm 2 ) or less. When the total opposing area S is within these ranges, it is particularly preferable that S / (dt·Vc) is 80cm or less. -2 or less than 79cm -2 In the following cases, it is easy to ensure higher HR discharge performance and also easy to obtain excellent results in overall discharge performance, which will be described later.

[0047] The total opposing area S is 1000cm 2 or more (or 1200cm 2 over)4000cm 2 Below, 1400cm 2 or more (or 1500cm 2 over)4000cm 2 Below, 1000cm 2 or more (or 1200cm 2 over)3000cm 2 Below, 1400cm 2 or more (or 1500cm 2 over)3000cm 2 Below, 1000cm 2 More than 2000cm 2 (or 1700cm 2 ) or less, 1200cm 2 More than 2000cm 2 (or 1700cm 2 ) or less, 1400cm 2 More than 2000cm 2 (or 1700cm 2 ) or less, or 1500 cm 2 More than 2000cm 2 (or 1700cm 2 ) or less.

[0048] (Analysis or measurement of positive electrode plate or positive electrode material) Analysis or measurement of the positive plate or positive electrode material is carried out on a positive plate removed from a fully charged lead-acid battery.

[0049] (1) Measurement of the density Dp of the positive electrode material The method for measuring the density Dp of the positive electrode material is described below. Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain the positive electrode plate to be analyzed. The obtained positive electrode plate is washed with water and dried to remove the electrolyte from the positive electrode plate. A pH test paper is pressed against the washed positive electrode plate surface until no change in color is confirmed. The washed positive electrode plate is dried at 50±5°C for approximately 24 hours. After drying, if the positive electrode plate contains an adhesive material, the adhesive material is removed from the positive electrode plate by peeling. Next, the positive electrode material is separated from the center of the positive electrode plate in the surface direction to obtain an unpulverized sample (Sample A).

[0050] The density (bulk density) of unpulverized sample A is determined by mercury intrusion porosimetry using a mercury porosimeter. More specifically, a predetermined amount of unpulverized sample A is first collected and its mass is measured. This sample A is placed in a measurement vessel of the mercury porosimeter, evacuated under reduced pressure, and then filled with mercury at a pressure of 0.5 psia to 0.55 psia (≒ 3.45 kPa to 3.79 kPa). The bulk volume of sample A is measured, and the measured mass of sample A is divided by the bulk volume to determine the density of the positive electrode material. The bulk volume is determined by subtracting the injected volume of mercury from the volume of the measurement vessel. An automatic porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation is used as the mercury porosimeter. When the electrode plate assembly includes one positive electrode plate, the density Dp of the positive electrode material is determined for the positive electrode material collected from that positive electrode plate. When the electrode plate assembly contains two positive electrodes, the density Dp of the positive electrode material is the average of the values obtained for the positive electrode material sampled from each of the two positive electrodes. When the electrode plate assembly contains three or more positive electrodes, the density Dp of the positive electrode material is the average of the values obtained for the positive electrode material sampled from two positive electrodes arbitrarily selected from the positive electrodes other than the electrodes at the ends of the electrode plate assembly. However, when two of the three positive electrodes are the electrodes at the ends of the electrode plate assembly, the density Dp of the positive electrode material is obtained for the positive electrode material sampled from the remaining positive electrode plate.

[0051] (2) Measurement of the total area S between the electrodes The area s1 (cm) of the overlapping portion of the projection shapes of the positive electrode material on the surface of the positive electrode plate facing the negative electrode plate and the negative electrode material on the negative electrode plate projected in the thickness direction of the electrode plate. 2 For one electrode plate group, the area s1 is calculated for each surface of the positive electrode plate facing the negative electrode, and the total area s1 for all opposing surfaces is calculated to obtain the total opposing area S between the electrode plates.

[0052] In this specification, the fully charged state of a flooded lead-acid battery is defined by JIS D 5301:2019. More specifically, a fully charged state is defined as a state in which a lead-acid battery is charged in a water tank at 25°C ± 2°C at a current (A) 0.2 times the value (unit: Ah) of the rated capacity, measured every 15 minutes, until the terminal voltage (V) during charging or the electrolyte density converted to a temperature of 20°C shows a constant value to three significant digits three times consecutively. For a valve-regulated lead-acid battery, the fully charged state is defined as a state in which charging is terminated when the charging current during constant voltage charging reaches a value (A) 0.005 times the value (unit: Ah) of the rated capacity, measured every 15 minutes in a water tank at 25°C ± 2°C at a current (A) 0.2 times the value (unit: Ah) of the rated capacity, at a constant current / constant voltage of 2.23 V / cell.

[0053] In this specification, a fully charged lead-acid battery refers to a lead-acid battery that has already been chemically formed and is fully charged. The lead-acid battery may be fully charged immediately after chemical formation, or after a certain period of time has passed since chemical formation (for example, a lead-acid battery that has been in use (preferably in the early stages of use) after chemical formation may be fully charged). A battery in the early stages of use refers to a battery that has not been in use for very long and has hardly deteriorated.

[0054] (others) An unformed paste-type positive electrode plate can be obtained, for example, by filling a positive electrode current collector with a positive electrode paste, aging it, and drying it. The positive electrode paste is prepared, for example, by kneading lead powder, additives (such as reinforcing materials), water, and sulfuric acid. The density Dp of the positive electrode material can be adjusted by adjusting the amounts of lead powder, water, and sulfuric acid in the positive electrode paste. A positive electrode plate can be obtained by forming the unformed positive electrode plate.

[0055] The formation may be performed, for example, by placing a plate assembly including unformed positive plates and an electrolyte containing sulfuric acid in a battery case of a lead-acid battery, and charging the plate assembly in a state in which the electrolyte has permeated the plate assembly. However, the formation may also be performed before assembling the lead-acid battery or the plate assembly.

[0056] (negative plate) The negative electrode plate is composed of, for example, a negative electrode current collector and a negative electrode material.

[0057] The negative electrode current collector may be formed in the same manner as the positive electrode current collector, for example. A lattice-shaped current collector may also be used as the negative electrode current collector.

[0058] The lead alloy used for the negative electrode current collector may be any of a Pb-Sb alloy, a Pb-Ca alloy, and a Pb-Ca-Sn alloy. These lead or lead alloys may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, and Cu.

[0059] The negative electrode current collector may have a surface layer. The surface layer and the inner layer of the negative electrode current collector may have different compositions. The surface layer may be formed on a part of the negative electrode current collector. For example, the surface layer may be formed only on the grid portion, the edge portion, or the frame portion of the negative electrode current collector.

[0060] The density Dn of the negative electrode material is, for example, 4 g / cm 3 From the viewpoint of making it easier to adjust the Dn / Dp ratio and making it easier to demonstrate the effect of S / (dt Vc), Dn is set to 4.3 g / cm 3 More than 4.4 g / cm is preferable. 3 From the viewpoint of easily ensuring higher HR discharge performance, the density Dn of the negative electrode material is, for example, 5 g / cm 3 is less than 4.6 g / cm 3 It may be the following:

[0061] The density Dn of the negative electrode material is 4 g / cm 3 More than 5g / cm 3 or less (or 4.6g / cm 3 below), 4.3g / cm 3 More than 5g / cm 3 or less (or 4.6g / cm 3 or less), or 4.4 g / cm 3 More than 5g / cm 3or less (or 4.6g / cm 3 (See below) may also be used.

[0062] The negative electrode material contains a negative electrode active material (lead or lead sulfate) that generates capacity through an oxidation-reduction reaction. The negative electrode material may contain additives as needed. Preferred additives include organic shrinkage inhibitors, carbonaceous materials, and barium sulfate. In addition to these additives, the negative electrode material may also contain other additives (e.g., reinforcing materials such as resin fibers).

[0063] Examples of organic shrink-proofing agents include lignin compounds and synthetic organic shrink-proofing agents. Examples of lignin compounds include lignin and lignin derivatives (for example, lignin sulfonic acid or its salts (such as alkali metal salts, e.g., sodium salts)). Synthetic organic shrink-proofing agents are organic polymers containing elemental sulfur. Examples of synthetic organic shrink-proofing agents include condensates of compounds having a sulfur-containing group and an aromatic ring (such as phenol compounds and aniline compounds) with aldehyde compounds (aldehydes or condensates thereof, e.g., formaldehyde). However, the organic shrink-proofing agents are not limited to these specific examples.

[0064] The negative electrode material may contain one organic shrinkage inhibitor or a combination of two or more organic shrinkage inhibitors.

[0065] The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more, and may be, for example, 1% by mass or less, or 0.5% by mass or less.

[0066] Examples of the carbonaceous material include carbon black, graphite (artificial graphite, natural graphite, etc.), hard carbon, soft carbon, etc. The negative electrode material may contain one type of carbonaceous material or two or more types of carbonaceous materials.

[0067] The content of the carbonaceous material in the negative electrode material is, for example, 0.05 mass % or more, or may be 0.1 mass parts or more, and the content of the carbonaceous material is, for example, 5 mass % or less.

[0068] The content of barium sulfate in the negative electrode material is, for example, 0.05% by mass or more, or may be 0.1% by mass or more, and the content of barium sulfate is, for example, 3% by mass or less.

[0069] (Analysis or measurement of negative electrode plate or negative electrode material) Analysis or measurement of the negative plate or negative electrode material is carried out on a negative plate removed from a fully charged lead-acid battery.

[0070] (1) Measurement of the density Dn of the negative electrode material In the same manner as for the density Dp of the positive electrode material, a fully charged lead-acid battery is disassembled to obtain the negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. The washing is continued until a pH test paper is pressed against the washed surface of the negative electrode plate and the color of the test paper does not change. However, the washing time should be within 2 hours. The washed negative electrode plate is dried in a reduced pressure environment at 50±5°C for approximately 24 hours. After drying, if the negative electrode plate contains an adhesive material, the adhesive material is removed from the negative electrode plate by peeling. Next, the negative electrode material is separated from near the center of the negative electrode plate in the surface direction to obtain an unpulverized sample (sample B). The density Dn of the negative electrode material can be determined using the same procedure as for the density Dp of the positive electrode material, except that sample B is used instead of sample A.

[0071] (2) Analysis of the components in the negative electrode material As in the case of (1) above, a negative electrode plate obtained from a fully charged lead-acid battery is washed with water and dried. If an adhesive material is included in the negative electrode plate after drying, the adhesive material is removed, and the negative electrode material is separated from the negative electrode plate to obtain a sample (hereinafter referred to as sample C). Sample C is pulverized as necessary and subjected to analysis.

[0072] (2-1) Quantitative determination of organic shrinkage inhibitor The crushed sample C is immersed in a 1 mol / L NaOH aqueous solution to extract the organic shrinkage inhibitor. Insoluble components are removed by filtration from the NaOH aqueous solution containing the extracted organic shrinkage inhibitor, and the filtrate (hereinafter also referred to as filtrate D) is recovered.

[0073] A predetermined amount of filtrate D is measured, desalted, concentrated, and dried to obtain a powder of the organic shrinkage preventer (hereinafter also referred to as sample E). Desalting can be performed using a desalting column, by passing filtrate D through an ion exchange membrane, or by placing filtrate D in a dialysis tube and immersing it in distilled water.

[0074] The organic shrinkage inhibitor is identified by combining information obtained from the infrared spectrum of sample E, the ultraviolet-visible absorption spectrum of a solution obtained by dissolving sample E in distilled water or the like, the nuclear magnetic resonance (NMR) spectrum of a solution obtained by dissolving sample E in a solvent such as heavy water, or information obtained from pyrolysis GC-MS, which can obtain information on the individual compounds that make up the substance.

[0075] The ultraviolet-visible absorption spectrum of the filtrate D is measured. The content of the organic shrinkage inhibitor in the negative electrode material is quantified from the spectral intensity, the calibration curve prepared in advance, the measured amount of filtrate D, and the mass of sample C. If the structural formula of the organic shrinkage inhibitor to be analyzed cannot be precisely identified and a calibration curve for the same organic shrinkage inhibitor cannot be used, a calibration curve is prepared using an available organic shrinkage inhibitor that exhibits a similar ultraviolet-visible absorption spectrum, infrared spectrum, NMR spectrum, etc. to the organic shrinkage inhibitor to be analyzed.

[0076] (2-2) Quantitative Analysis of Carbonaceous Materials and Barium Sulfate 50 ml of 20% by mass nitric acid is added to 10 g of crushed sample C, and the mixture is heated for approximately 20 minutes to dissolve the lead components as lead ions. The resulting solution is filtered to separate out solids such as carbonaceous materials and barium sulfate.

[0077] The obtained solid content is dispersed in water to form a dispersion, and then components other than the carbonaceous material and barium sulfate (e.g., reinforcing material) are removed from the dispersion using a sieve. Next, the dispersion is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter together with the filtered sample is dried in a dryer at 110°C ± 5°C. The filtered sample is a mixed sample of the carbonaceous material and barium sulfate. The mass of the membrane filter is subtracted from the total mass of the dried mixed sample (hereinafter referred to as sample F) and the membrane filter to determine the mass of sample F (M m ) is measured. Then, sample F is placed in a crucible together with the membrane filter and burnt at 1300°C or higher to be incinerated. The remaining residue is barium oxide. The mass of barium oxide is converted to the mass of barium sulfate to determine the mass of barium sulfate (M B ) to find the mass M m to mass M B The mass of the carbonaceous material is calculated by subtracting the mass of the barium sulfate from the mass of the carbonaceous material obtained. The ratio (percentage) of the mass of the obtained barium sulfate and the mass of the carbonaceous material to the mass of sample C is calculated. In this way, the content of barium sulfate and the content of the carbonaceous material in the negative electrode material are determined.

[0078] (others) An unformed negative electrode plate is produced, for example, by applying or filling a negative electrode paste onto a negative electrode current collector, followed by aging and drying. The negative electrode active material in a charged state is sponge lead, but an unformed negative electrode plate is typically produced using lead powder. More specifically, the negative electrode paste used to produce an unformed negative electrode plate is prepared, for example, by adding water and sulfuric acid (or an aqueous sulfuric acid solution) to lead powder and, if necessary, various additives (such as an organic shrinkage inhibitor or a carbonaceous material), and kneading the mixture. The density Dn of the negative electrode material can be adjusted by adjusting the amount of lead powder, water, and sulfuric acid in the negative electrode paste. During aging, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and at high humidity. A negative electrode plate is produced, for example, by chemically forming an unformed negative electrode plate.

[0079] The formation may be performed, for example, by placing a plate assembly including unformed negative plates and an electrolyte containing sulfuric acid in a lead-acid battery container, and charging the plate assembly while the electrolyte is permeated into the plate assembly. However, the formation may also be performed before assembling the lead-acid battery or the plate assembly. The formation produces spongy lead.

[0080] (separator) The separator may be, for example, a microporous membrane. The microporous membrane is a porous sheet mainly composed of components other than fiber components. The microporous membrane can be obtained, for example, by extruding a composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores.

[0081] The microporous membrane is preferably made of an acid-resistant material, and is preferably a microporous membrane mainly made of a polymer component. The polymer component is preferably a polyolefin (polyethylene, polypropylene, etc.). The pore-forming agent may be at least one selected from the group consisting of polymer powder and oil.

[0082] The microporous membrane may have a single-layer structure or a multi-layer structure (or laminate structure). In a multi-layer separator, two adjacent layers may be interlocked with each other via the unevenness at their interfaces.

[0083] The separator may be made of nonwoven fabric. Nonwoven fabric is a mat in which fibers are intertwined without being woven, and is mainly composed of fibers. For example, 60% by mass or more of the nonwoven fabric is made of fibers. Examples of fibers include glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (polyethylene terephthalate fibers, etc.)), and pulp fibers. Among these, glass fibers are preferable. The nonwoven fabric may contain components other than fibers (for example, acid-resistant inorganic powder, polymers as binders), etc.

[0084] The separator may be made of, for example, only a microporous membrane or only a nonwoven fabric.

[0085] The separator preferably includes at least a microporous membrane. Such a separator includes at least a base portion made of a microporous membrane. However, a microporous membrane is prone to permeation short-circuiting under certain conditions (such as a narrow electrode gap). Therefore, when the separator includes a microporous membrane, the lead-acid battery preferably includes a mechanism for separating the negative electrode plate from the base portion. Such a mechanism may be included in the separator or may be included in the lead-acid battery (or electrode plate group) separately from the separator. Such a mechanism includes ribs protruding from the base portion toward the negative electrode plate and a mat interposed between the negative electrode plate and the separator. The mat may be laminated with the microporous membrane to form a separator with a multilayer structure, or the separator including the microporous membrane and the mat may simply be stacked together. The nonwoven fabric described above may be used as the mat.

[0086] The separator including the microporous membrane may have a base portion and a rib protruding from the base portion. More specifically, the separator may have a base portion having a first surface on the negative electrode plate side and a second surface on the positive electrode plate side, and a rib (hereinafter referred to as the first rib) protruding from the first surface of the base portion toward the negative electrode plate. The presence of the first rib can separate the negative electrode plate from the base portion, thereby enhancing the effect of suppressing permeation short circuits. The separator may also have a rib (hereinafter referred to as the second rib) protruding from the second surface toward the positive electrode plate, as necessary. Using a separator with a second rib can suppress oxidative degradation of the base portion, which is advantageous from the perspectives of suppressing short circuits and extending the lifespan.

[0087] The first rib and the second rib are preferably formed on the surface of the separator at least in a portion facing the region where the electrode material of each electrode plate is present. Typically, multiple ribs are formed on each surface of the base.

[0088] The average thickness of the base portion is, for example, 0.1 mm or more, preferably 0.15 mm or more. When the average thickness of the base portion is in this range, the strength of the separator is increased, which is advantageous from the viewpoint of reducing permeation short-circuiting or oxidative degradation. From the viewpoint of easily ensuring a higher capacity, the average thickness of the base portion is, for example, 0.3 mm or less.

[0089] The average height of the first ribs is, for example, 0.05 mm or more. From the viewpoint of further enhancing the effect of suppressing permeation short circuits, the average height of the first ribs may be 0.08 mm or more. From the viewpoint of ensuring high capacity, the average height of the first ribs is preferably 0.3 mm or less. The separator preferably has first ribs of such an average height on the first surface of the base portion, at least in a region facing a region of the negative electrode plate where the negative electrode material is present.

[0090] From the viewpoint of enhancing the effect of suppressing oxidation degradation of the base portion, the average height of the second ribs is preferably 0.3 mm or more. From the viewpoint of ensuring high capacity, the average height of the second ribs is preferably 1.0 mm or less, and may be 0.7 mm or less. The separator preferably has second ribs of such an average height on the second surface of the base portion, at least in a region facing the region where the positive electrode material of the positive electrode plate is present.

[0091] The average thickness of the mat is, for example, 0.1 mm or more. From the viewpoint of further enhancing the effect of suppressing permeation short circuits, the average thickness of the mat may be 0.5 mm or more. From the viewpoint of ensuring high capacity, the average thickness of the mat may be 2 mm or less.

[0092] The average base thickness, average rib height, and average mat thickness are determined on separators or mats removed from fully charged lead-acid batteries, cleaned, and dried under subatmospheric pressure.

[0093] The average thickness of the base portion is determined by measuring the thickness of the base portion at five arbitrarily selected points in a cross-sectional photograph of the separator and averaging the measured values.

[0094] The average height of the first rib is determined by averaging the heights of the first rib measured at 10 arbitrarily selected locations on the first surface of the base. The height of the first rib refers to the distance from the first surface of the base at a predetermined position on the first rib to the top of the first rib. If the surface of the base is not flat, the height of the first rib is defined as the distance from the highest point on the first surface of the base to the top of the first rib at a predetermined position on the first rib when the separator is placed flat with the first rib side facing up.

[0095] The average height of the second rib is determined in the same manner as for the first rib. The height of the second rib is the distance from the second surface of the base portion at a predetermined position on the second rib to the top of the second rib, in the same manner as for the first rib.

[0096] The average thickness of the mat is determined by measuring the thickness of the mat at five arbitrarily selected points in a cross-sectional photograph of the mat or separator and averaging the measured values.

[0097] The separator may be sheet-shaped or bag-shaped. A single sheet-shaped separator may be sandwiched between the positive electrode plate and the negative electrode plate. Alternatively, the electrode plates may be sandwiched between a single folded sheet-shaped separator. In this case, a positive electrode plate sandwiched between folded sheet-shaped separators may be stacked on top of a negative electrode plate sandwiched between folded sheet-shaped separators, or one of the positive electrode plate and the negative electrode plate may be sandwiched between folded sheet-shaped separators and stacked on top of the other electrode plate. Alternatively, a sheet-shaped separator may be folded into an accordion-like shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the accordion-like separators so that the separator is interposed between them. When a separator folded like an accordion is used, the separator may be arranged so that the folded portions are aligned with the horizontal direction of the lead-acid battery (e.g., so that the folded portions are parallel to the horizontal direction) or so that the folded portions are aligned with the vertical direction (e.g., so that the folded portions are parallel to the vertical direction). In a separator folded like an accordion, recesses are formed alternately on both main surfaces of the separator. Because the positive and negative plates usually have lugs on the top, when the separator is arranged so that the folded portions are aligned with the horizontal direction of the lead-acid battery, the positive and negative plates are positioned in the recesses on only one main surface of the separator (i.e., a double separator is interposed between adjacent positive and negative plates). When the separator is arranged so that the folded portion is aligned with the vertical direction of the lead-acid battery, the positive electrode plate may be accommodated in the recess on one main surface side, and the negative electrode plate may be accommodated in the recess on the other main surface side (that is, a single separator may be interposed between adjacent positive and negative electrode plates.) When a pouch-shaped separator is used, the pouch-shaped separator may accommodate either the positive electrode plate or the negative electrode plate.

[0098] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, which may be gelled as necessary.

[0099] The electrolyte may contain cations (for example, metal cations) and / or anions (for example, anions other than sulfate anions (such as phosphate ions)) as needed.

[0100] The metal cation is preferably at least one selected from the group consisting of Al ions, Na ions, Li ions, and Mg ions. When the electrolyte contains such metal cations, lead is less likely to grow into dendrite crystals, thereby enhancing the effect of suppressing permeation short circuits even when the inter-electrode distance dt is relatively small. An electrolyte containing such metal cations may be combined with a mechanism for separating the negative electrode plate from the separator base. While either of these mechanisms alone can provide the effect of suppressing permeation short circuits, combining them can further enhance the effect of suppressing permeation short circuits.

[0101] The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolyte at 20°C is, for example, 1.35 or less, and may be 1.32 or less.

[0102] The specific gravity of the electrolyte at 20° C. may be 1.20 or more and 1.35 or less, 1.20 or more and 1.32 or less, 1.25 or more and 1.35 or less, or 1.25 or more and 1.32 or less.

[0103] (others) A lead-acid battery may include one cell or two or more cells. When a lead-acid battery includes multiple cells (in other words, multiple electrode plate groups), the multiple electrode plate groups may be connected in series.

[0104] The number of each electrode plate in the electrode plate group may be one or two or more. From the viewpoint of ensuring higher capacity, the number of negative electrode plates included in the electrode plate group is preferably two or more, and may be four or more, or six or more. If the number of negative electrode plates included in the electrode plate group is m, the number of positive electrode plates is (m-1) or more and (m+1) or less when m≧2, and is 1 or 2 when m=1.

[0105] The distance dt between the electrodes is, for example, 0.05 cm or more. From the viewpoint of ensuring a certain amount of electrolyte to ensure higher HR discharge performance and easily achieving a higher permeation short-circuit suppression effect, the distance dt between the electrodes is preferably 0.06 cm or more. The distance dt between the electrodes is, for example, 0.1 cm or less. From the viewpoint of easily achieving higher HR discharge performance, the distance dt between the electrodes is preferably 0.08 cm or less.

[0106] The distance dt between the electrodes may be 0.05 cm or more (or 0.06 cm or more) and 0.1 cm or less, or 0.05 cm or more (or 0.06 cm or more) and 0.08 cm or less.

[0107] The inter-plate distance dt is determined for a fully charged lead-acid battery. More specifically, first, a fully charged lead-acid battery is disassembled, the plate group is removed, the number of gaps between the plates in the plate group (n-1) is determined, and the inner dimension Lc (cm) of the cell chamber in the direction parallel to the stacking direction of the plates is measured. Next, the positive and negative electrodes are removed from the electrode assembly, and the separator located further outward from the outermost electrode plate of the electrode assembly (the outermost separator) is removed. The thicknesses of all the electrodes included in the electrode assembly are measured and summed to determine the total value Te (cm). The thickness of the outermost separator is measured to determine the total thickness Ts (cm). The thickness of the outermost separator is basically the total thickness. However, as mentioned above, if wall ribs are formed in the cell chambers etc. that contact the outermost separator and the outermost separator has an outer rib, depending on the relationship between the heights of the wall ribs and the outer rib, the thickness of the outermost separator may be calculated by subtracting the height of the outer rib from the total thickness. From these values, the distance between the electrodes dt can be calculated based on the above formula.

[0108] In a lead-acid battery, the volume Vc is determined, for example, according to the desired capacity, size, etc. of the lead-acid battery. For example, the volume Vc is 200 cm 3 More than 300cm 3 The volume Vc may be, for example, 1500 cm3 is less than 1000 cm 3 or less than 600cm 3 However, the volume Vc is not limited to this range.

[0109] The volume Vc is 200 cm 3 or more (or 300cm 3 over)1500cm 3 Below, 200cm 3 or more (or 300cm 3 over)1000cm 3 or less than 200cm 3 or more (or 300cm 3 over)600cm 3 It may be the following:

[0110] A lead-acid battery can be obtained, for example, by a manufacturing method including a step of housing a plate assembly and an electrolyte in a cell chamber of a battery case. Each cell of the lead-acid battery includes a plate assembly and an electrolyte housed in each cell chamber. The plate assembly is assembled, for example, by stacking positive electrode plates, negative electrode plates, and a separator with the separator interposed between the positive and negative electrode plates prior to housing in the cell chamber. The positive electrode plates, negative electrode plates, and separator are typically prepared prior to assembling the plate assembly. When a mat is used, the mat is typically prepared prior to assembling the plate assembly. The electrolyte is prepared prior to housing in the cell chamber. When a lead-acid battery has one plate assembly, the battery case does not need to be divided into multiple cell chambers, and the plate assembly and the electrolyte may be housed in the battery case.

[0111] The method for manufacturing a lead-acid battery may include, after the step of housing the electrode plate group and the electrolyte in the cell chamber, a step of chemically converting at least one of the positive electrode plate and the negative electrode plate, as necessary.

[0112] (evaluation) The HR discharge performance, capacity, overall discharge performance, and permeable short circuit of the lead-acid battery are evaluated by the following procedures, respectively. (1)HR discharge performance A fully charged lead-acid battery is discharged at a constant current for 30 seconds at -18°C ± 1°C, and the discharge current is determined so that the terminal voltage at 30 seconds is 1.2V / cell. HR discharge performance is evaluated based on the discharge current value. Setting the discharge temperature to a low temperature of around -18°C can easily result in differences in HR discharge performance. HR discharge performance when discharging at such low temperatures is sometimes called cold cranking amp (CCA) performance.

[0113] (2) Capacity (reserve capacity test) Conduct the discharge capacity test of lead-acid batteries in a water tank at 25°C ± 2°C as follows: Discharge the battery at a constant current of 25A down to 1.75V / cell, then charge it at a constant current (unit: A) that is 0.2 times the value listed in the 5-hour rate rated capacity (unit: Ah) up to 135% of the discharged amount. This discharge and charge cycle is repeated three times in total, and the discharge duration of the third cycle is calculated. The capacity performance of the lead-acid battery is evaluated based on this duration.

[0114] (3) Overall discharge performance The balance between HR discharge performance and capacity is evaluated by the overall discharge performance. The overall discharge performance is expressed as the product of the HR discharge performance obtained in (1) above and the capacity obtained in (2) above. When the HR discharge performance and capacity are each expressed as a relative value with the HR discharge performance and capacity of a reference example set to 100, the overall discharge performance is the product of the HR discharge performance and the capacity divided by 100. A larger overall discharge performance value indicates a higher capacity, improved HR discharge performance, or suppressed deterioration of HR discharge performance.

[0115] (4) Penetrating Short Circuit The lead-acid battery is placed in a thermostatic water bath at 25°C ± 2°C, and a charge-discharge cycle consisting of the following steps 1 to 4 is repeated five times. Note that this test is conducted under conditions that promote the occurrence of permeation short circuits. Therefore, the incidence of permeation short circuits in this test is significantly higher than the incidence of permeation short circuits under actual usage conditions of lead-acid batteries. Step 1: Discharge the lead-acid battery at a constant current of 0.05 C (A) until the voltage reaches 1.0 V / cell. Here, C is the rated capacity expressed in units of Ah (ampere-hours). Step 2: Connect a 10 Ω resistor to the lead-acid battery that has been through step 1 and discharge it for a specified period of time. The discharge period is 26 days if the rated capacity is 30 Ah, 28 days if it is 32 Ah, and 47 days if it is 54 Ah. Step 3: The lead-acid battery that has passed through step 2 is charged for 10 minutes at a constant voltage of 2.4V / cell, with a maximum charging current of 50A. Step 4: Charge at a constant current of 0.05 C(A) for 27 hours.

[0116] Next, the lead-acid batteries that had undergone the above charge-discharge cycles were disassembled and visually inspected for the presence or absence of short circuits. The same test was carried out on a total of 20 lead-acid batteries, and the effectiveness of suppressing permeation short circuits was evaluated based on the number of lead-acid batteries in which permeation short circuits did not occur.

[0117] The components described herein may be combined in any manner.

[0118] A lead-acid battery according to one aspect of the present invention will be summarized below.

[0119] (1) A lead-acid battery, The lead-acid battery includes at least one cell including a plate pack and an electrolyte; the electrode plate group includes positive electrode plates including a positive electrode material, negative electrode plates including a negative electrode material, and a separator interposed between the positive electrode plates and the negative electrode plates; a ratio Dn / Dp of a density Dn of the negative electrode material to a density Dp of the positive electrode material satisfies Dn / Dp≧1.05; The sum of the areas of the positive electrode plates facing the negative electrode plates in the electrode plate group S (cm 2 ), the average value dt (cm) of the distance between the adjacent positive and negative plates, and the volume Vc (cm 3 ) is 55 (cm -2 )≦S / (dt·Vc)≦82(cm -2) Lead-acid battery.

[0120] (2) In (1) above, the sum S, the average value dt, and the volume Vc are 58 (cm -2 )≦S / (dt·Vc) may be satisfied, and 58.5(cm -2 )≦S / (dt·Vc) may be satisfied.

[0121] (3) In the above (1) or (2), the sum S, the average value dt, and the volume Vc satisfy the following conditions: S / (dt·Vc)≦80(cm -2 ) may be satisfied, and S / (dt·Vc)≦79(cm -2 ) may be satisfied, or S / (dt·Vc)≦78.5(cm -2 ) may be satisfied.

[0122] (4) In any one of the above (1) to (3), the sum S is 1000 cm 2 More than 1200cm 2 More than 1400cm 2 or more, or 1500cm 2 It may be more than that.

[0123] (5) In any one of the above (1) to (4), the sum S is 4000 cm 2 Below, 3000cm 2 Below, 2000cm 2 or less than 1700cm 2 It may be the following:

[0124] (6) In any one of the above (1) to (4), the sum S is 1200 cm 2 More than 2000cm 2 (or 1700cm 2 ) or less, or 1500 cm 2 More than 2000cm 2 (or 1700cm 2 ) or less.

[0125] (7) In (6) above, S / (dt·Vc) is 80cm -2or less than 79cm -2 It may be the following:

[0126] (8) In any one of the above (1) to (7), the Dn / Dp ratio may be 1.3 or less, or 1.2 or less.

[0127] (9) In any one of the above (1) to (8), the density Dp of the positive electrode material is 3.7 g / cm 3 or more, or 3.75 g / cm 3 It may be more than that.

[0128] (10) In any one of the above (1) to (9), the density Dp of the positive electrode material is 4.5 g / cm 3 Below, 4.30g / cm 3 or less, or 4.20 g / cm 3 It may be the following:

[0129] (11) In any one of the above (1) to (10), the density Dn of the negative electrode material is 4 g / cm 3 More than 4.3g / cm 3 or more than 4.4 g / cm 3 It may be more than that.

[0130] (12) In any one of the above (1) to (11), the density Dn of the negative electrode material is 5 g / cm 3 or less, or 4.6 g / cm 3 It may be the following:

[0131] (13) In any one of the above (1) to (12), the negative electrode material may contain an organic shrinkage preventer.

[0132] (14) In the above (13), the content of the organic shrinkage preventer in the negative electrode material may be 0.01% by mass or more.

[0133] (15) In the above (13) or (14), the content of the organic shrinkage preventer in the negative electrode material may be 1% by mass or less, or 0.5% by mass or less.

[0134] (16) In any one of the above (1) to (15), the negative electrode material may contain a carbonaceous material.

[0135] (17) In the above (16), the content of the carbonaceous material in the negative electrode material may be 0.05 mass % or more, or 0.1 mass parts or more.

[0136] (18) In the above (16) or (17), the content of the carbonaceous material in the negative electrode material may be 5% by mass or less.

[0137] (19) In any one of the above (1) to (18), the negative electrode material may contain barium sulfate.

[0138] (20) In the above (19), the content of the barium sulfate in the negative electrode material may be 0.05% by mass or more, or 0.1% by mass or more.

[0139] (21) In the above (19) or (20), the content of the barium sulfate in the negative electrode material may be 3 mass % or less.

[0140] (22) In any one of the above (1) to (21), the separator may include a base portion, and the lead-acid battery may include a mechanism for separating the negative electrode plate and the base portion.

[0141] (23) In the above (22), the mechanism may be a rib (first rib) protruding from the base portion toward the negative electrode plate, or a mat interposed between the negative electrode plate and the separator.

[0142] (24) In the above (22) or (23), the average thickness of the base portion may be 0.1 mm or more, or 0.15 mm or more.

[0143] (25) In any one of the above (22) to (24), the average thickness of the base portion may be 0.3 mm or less.

[0144] (26) In any one of (22) to (25) above, the separator may have a first rib protruding from the base portion toward the negative electrode plate, and the average height of the first rib may be 0.05 mm or more, or 0.08 mm or more.

[0145] (27) In any one of the above (22) to (26), the separator may have a first rib protruding from the base portion toward the negative electrode plate, and the average height of the first rib may be 0.3 mm or less.

[0146] (28) In any one of the above (22) to (27), the separator may include a second rib that protrudes from the base portion toward the positive electrode plate.

[0147] (29) In the above (28), the average height of the second rib may be 0.3 mm or more.

[0148] (30) In the above (28) or (29), the average height of the second rib may be 1.0 mm or less, or 0.7 mm or less.

[0149] (31) In any one of the above (22) to (30), the lead-acid battery may include a mat interposed between the negative electrode plate and the separator, and the average thickness of the mat may be 0.1 mm or more, or 0.5 mm or more.

[0150] (32) In any one of the above (22) to (31), the lead-acid battery may include a mat interposed between the negative electrode plate and the separator, and the average thickness of the mat may be 2 mm or less.

[0151] (33) In any one of the above (1) to (32), the electrolytic solution may contain at least one ion selected from the group consisting of Al ions, Na ions, Li ions, and Mg ions.

[0152] (34) In any one of the above (1) to (33), the specific gravity of the electrolyte at 20° C. in the lead-acid battery in a fully charged state may be 1.20 or more, or 1.25 or more.

[0153] (35) In any one of the above (1) to (34), the specific gravity of the electrolyte at 20° C. in the lead-acid battery in a fully charged state may be 1.35 or less, or 1.32 or less.

[0154] (36) In any one of the above (1) to (35), the number of negative electrode plates included in the electrode plate group may be one, two or more, four or more, or six or more.

[0155] (37) In any one of the above (1) to (36), when the number of negative electrode plates included in the electrode plate group is m, the number of positive electrode plates may be (m-1) or more and (m+1) or less when m≧2, and may be 1 or 2 when m=1.

[0156] (38) In any one of the above (1) to (37), the distance dt between the electrodes may be 0.05 cm or more, or 0.06 cm or more.

[0157] (39) In any one of the above (1) to (38), the distance dt between the electrodes may be 0.1 cm or less, or 0.08 cm or less.

[0158] (40) In any one of the above (1) to (39), the volume Vc is 200 cm 3 or more, or 300cm 3 It may be more than that.

[0159] (41) In any one of the above (1) to (40), the volume Vc is 1500 cm 3 Below, 1000cm 3 or less than 600cm 3 It may be the following:

[0160] FIG. 1 shows an external view of an example of a lead-acid battery according to one embodiment of the present invention. The lead-acid battery 1 includes a battery case 12 that contains a plate group 11 and an electrolyte (not shown). The battery case 12 is divided into multiple cell chambers 14 by partition walls 13. Each cell chamber 14 contains one plate group 11. The opening of the battery case 12 is closed with a lid 15 that has a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a vent plug 18 for each cell chamber. When rehydrating, the vent plug 18 is removed and rehydration liquid is added. The vent plug 18 may have the function of venting gas generated in the cell chambers 14 to the outside of the battery.

[0161] Each electrode plate group 11 is formed by stacking multiple negative electrode plates 2 and multiple positive electrode plates 3 with separators 4 interposed between them. Here, a pouch-shaped separator 4 is shown housing the negative electrode plates 2, but the shape of the separator is not particularly limited. In a cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects multiple negative electrode plates 2 in parallel is connected to a through-connector 8, and a positive electrode shelf 5 that connects multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 outside the lid 15. In a cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode shelf 6, and a through-connector 8 is connected to the positive electrode shelf 5. The negative electrode column 9 is connected to a negative electrode terminal 16 outside the lid 15. Each through-connector 8 passes through a through-hole provided in the partition wall 13 to connect the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0162] The positive electrode shelf 5 is formed by welding together the lugs provided on the top of each positive electrode plate 3. The negative electrode shelf 6 is also formed by welding together the lugs provided on the top of each negative electrode plate 2.

[0163] The lid 15 of the lead-acid battery has a single structure (single lid), but this is not limited to the illustrated example. The lid 15 may have a double structure, for example, including an inner lid and an outer lid (or top lid). A lid having a double structure may have a reflux structure between the inner lid and the outer lid for returning the electrolyte to the battery (inside the inner lid) from a reflux port provided in the inner lid.

[0164] [Example] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0165] Lead-acid batteries E1 to E5 and C1 to C7 (1) Preparation of the positive electrode plate Lead powder, water, and dilute sulfuric acid are mixed to obtain a positive electrode paste. The amounts of water and dilute sulfuric acid are adjusted so that the density Dp of the positive electrode material obtained by the above-mentioned procedure is the value shown in Table 1. The positive electrode paste is filled into the mesh portion of an expanded grid made of a Pb-Ca-Sn alloy as a positive electrode current collector, and then aged and dried to obtain an unformed positive electrode plate.

[0166] (2) Preparation of the negative electrode plate A negative electrode paste is prepared by mixing lead powder, water, dilute sulfuric acid, sodium lignosulfonate as an organic shrinkage preventer, barium sulfate, and carbon black. The amounts of water and dilute sulfuric acid are adjusted so that the density Dn of the negative electrode material obtained by the procedure described above is the value shown in Table 1. The amounts of each component are also adjusted so that the contents of the organic shrinkage preventer, barium sulfate, and carbon black in the negative electrode material obtained by the procedure described above are 0.2 mass%, 0.6 mass%, and 0.3 mass%, respectively. The negative electrode paste is filled into the mesh portion of a negative electrode current collector, aged, and dried to obtain an unformed negative electrode plate.

[0167] (3) Preparation of lead-acid battery The unformed negative electrode plates are housed in a pouch-shaped separator made of a microporous polyethylene film, and six to eight unformed positive electrode plates and seven unformed negative electrode plates form an electrode plate assembly. The pouch-shaped separator is made of a microporous polyethylene film and has a second rib protruding toward the positive electrode plate. The average thickness of the base of the pouch-shaped separator is 0.25 mm, and the average height of the second rib is 0.45 mm. The number of positive and negative electrode plates is adjusted so that the total opposing area S and the inter-electrode distance dt, determined by the procedure described above, are the values shown in Table 1.

[0168] The electrode plate group is inserted into a battery case, a predetermined amount of sulfuric acid aqueous solution is poured in as the electrolyte, and chemical formation is performed inside the battery case to produce a wet lead-acid battery with a rated voltage of 12 V and a rated capacity of 32 Ah (5-hour rate). The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is 1.285. The above chemical formation brings the lead-acid battery into a fully charged state.

[0169] The lead-acid batteries fabricated as described above were evaluated for HR discharge performance and capacity using the methods described above. The effect of suppressing permeation short circuits was evaluated for some of the lead-acid batteries. Table 1 shows the evaluation results for each lead-acid battery as a relative value, with the evaluation result for lead-acid battery C1 set at 100. For the evaluation of HR discharge performance and capacity, a higher numerical value indicates a higher effect. For the evaluation of permeation short circuits, a higher numerical value indicates a better suppression of permeation short circuits.

[0170] The results are shown in Table 1. Lead-acid batteries E1 to E5 are examples, and lead-acid batteries C1 to C7 are comparative examples. The table also shows the overall discharge performance, that is, the value obtained by dividing the product of the HR discharge performance and capacity by 100 ((A) × (B) / 100 in the table).

[0171] [Table 1]

[0172] As shown in Table 1, when Dn / Dp satisfies Dn / Dp ≥ 1.05, the HR discharge performance tends to improve as S / (dt Vc) increases. This improvement is greater than when Dn / Dp < 1.05. Also, when Dn / Dp < 1.05, the HR discharge performance tends to improve as S / (dt Vc) increases. -2 On the other hand, when Dn / Dp ≥ 1.05, S / (dt Vc) is 82cm -2 When S / (dt·Vc) is changed, the behavior of the HR discharge performance is significantly different between when Dn / Dp<1.05 and when Dn / Dp≧1.05. When Dn / Dp≧1.05, the HR discharge performance is significantly lower than 55(cm -2 )≦S / (dt·Vc)≦82(cm -2 ) can ensure high HR discharge performance. It can also ensure high capacity. For E1 to E5, the overall discharge performance values are all high at 109 or more, and it can be seen that the decrease in HR discharge performance is kept low while ensuring high capacity.

[0173] Lead-acid batteries E6 to E11 and C8 to C11 A battery case (cell chamber) with internal dimensions corresponding to the volume Vc of the plate assembly shown in Tables 2A and 2B is selected, and a flooded lead-acid battery with a rated voltage of 12 V and a rated capacity of 30 Ah (Table 2A) or 54 Ah (Table 2B) at a 5-hour rate is fabricated. The number of positive and negative plates is adjusted so that the total facing area S and the inter-electrode distance dt obtained by the procedure described above are the values shown in Table 2A or Table 2B. Other than these, the lead-acid battery is fabricated by adjusting the inter-electrode distance dt, the total facing area S, the densities Dn and Dp of each electrode material, etc., to the values shown in the table in the same manner as for lead-acid batteries E1 to E5 or C1 to C7.

[0174] The lead-acid batteries fabricated as described above were evaluated for HR discharge performance and capacity using the methods described above. Table 2A shows the evaluation results for each lead-acid battery as a relative value, with the evaluation result for lead-acid battery C8 set to 100. Table 2B shows the evaluation results for each lead-acid battery as a relative value, with the evaluation result for lead-acid battery C10 set to 100.

[0175] [Table 2A]

[0176] [Table 2B]

[0177] As shown in Tables 2A and 2B, even if the total opposing area S and the volume Vc are changed, Dn / Dp ≥ 1.05 and 55 (cm -2 )≦S / (dt·Vc)≦82(cm -2 ) are satisfied, the same tendency as in Table 1 is observed. Even with E6 to E11, high HR discharge performance is obtained, and high capacity can be secured, resulting in excellent overall discharge performance.

[0178] Lead-acid batteries E12 to E22 and C12 to C22 The lead-acid batteries E12-14, E18-E22, C12, C13, and C16-C22 use a pouch-shaped separator made of a microporous polyethylene film, which has a first rib protruding toward the negative electrode plate and a second rib protruding toward the positive electrode plate. The average thickness of the base of the pouch-shaped separator is 0.20 mm, the average height of the first rib is 0.09 mm, and the average height of the second rib is 0.41 mm.

[0179] Lead-acid batteries E15 to E22 and C14 to C22 use an electrolyte containing Al ions. The specific gravity of this electrolyte at 20°C in a fully charged lead-acid battery is 1.285. The electrolyte is prepared by dissolving aluminum sulfate in a sulfuric acid solution so that the concentration of Al ions in the electrolyte in a fully charged lead-acid battery is 0.04 mol / L.

[0180] Other than these, the distance between the electrodes dt, the total surface area S, the density Dn and Dp of each electrode material, etc. are adjusted to the values shown in the table, similar to the lead-acid batteries E1 to E5 or C1 to C7. The flooded lead-acid battery produced in this way has a rated voltage of 12 V and a rated capacity of 32 Ah at a 5-hour rate.

[0181] The lead-acid batteries fabricated as described above were evaluated for HR discharge performance and capacity using the methods described above. The effectiveness of suppressing permeation short circuits was evaluated for some of the lead-acid batteries. Table 3 shows the evaluation results for each lead-acid battery as a relative value, with the evaluation result for lead-acid battery C1 set at 100.

[0182] The evaluation results are shown in Table 3. Lead-acid batteries E12 to E22 are examples, and lead-acid batteries C12 to C22 are comparative examples. These tables also show the results for lead-acid batteries E1 to E5 and C1 to C6.

[0183] [Table 3]

[0184] As shown in Table 3, when at least one of an electrolyte containing Al ions and a separator having a first rib is used, results similar to those shown in Table 1 are obtained. More specifically, when Dn / Dp≧1.05 and 55 (cm -2 )≦S / (dt·Vc)≦82(cm -2 ) is satisfied, high HR discharge performance and high capacity can be obtained. In all examples, the overall discharge performance value is high, at 109 or more, and it can be seen that the deterioration of HR discharge performance is suppressed to a low level while ensuring high capacity. In addition, by using at least one of an electrolyte containing Al ions and a separator having a first rib, the effect of suppressing permeation short circuits can be enhanced. [Industrial Applicability]

[0185] A lead-acid battery according to one aspect of the present invention is suitable for use as an IS lead-acid battery in a vehicle equipped with an idle reduction system. Furthermore, the lead-acid battery can be suitably used as a starting power source for a vehicle (such as an automobile or motorcycle) or as an industrial power storage device (such as a power source for an electric vehicle (such as a forklift)). These are merely examples, and the uses of the lead-acid battery are not limited to these. [Explanation of symbols]

[0186] 1:Lead acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive pole 8: Through connector 9: Negative pole 11: Plate group 12:Battery container 13: Bulkhead 14: Cell Room 15: Lid 16: Negative terminal 17: Positive terminal 18: Liquid vent plug

Claims

1. A lead-acid battery, The lead-acid battery includes at least one cell including a plate pack and an electrolyte; the electrode plate group includes positive electrode plates including a positive electrode material, negative electrode plates including a negative electrode material, and a separator interposed between the positive electrode plates and the negative electrode plates; a ratio Dn / Dp of a density Dn of the negative electrode material to a density Dp of the positive electrode material satisfies Dn / Dp≧1.05; The sum of the areas of the positive electrode plates facing the negative electrode plates in the electrode plate group S (cm ２ ), the average value dt (cm) of the distance between the adjacent positive and negative plates, and the volume Vc (cm ３ ) is 55 (cm －２ )≦S / (dt・Vc)≦82(cm －２ ) is satisfied, The average value dt (cm) satisfies 0.055 (cm)≦dt≦0.082 (cm).

2. The sum S, the average value dt, and the volume Vc are 58 (cm －２ 2. The lead-acid battery according to claim 1, wherein the relationship S / (dt·Vc) is satisfied.

3. The sum S, the average value dt, and the volume Vc are such that S / (dt·Vc)≦80 (cm －２ 3. The lead-acid battery according to claim 1 or 2, wherein the above condition is satisfied.

4. The lead acid battery according to any one of claims 1 to 3, wherein the electrolyte contains at least one selected from the group consisting of Al ions, Na ions, Li ions, and Mg ions.

5. the separator includes a base portion; The lead-acid battery according to any one of claims 1 to 4, further comprising a mechanism for separating the negative electrode plate from the base portion.

6. 6. The lead-acid battery according to claim 5, wherein the mechanism is a rib protruding from the base portion toward the negative electrode plate, or a mat interposed between the negative electrode plate and the separator.

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