Liquid-type lead storage battery and method for manufacturing same

Abstract

The present invention improves the performance rank of a liquid-type lead storage battery by increasing RC without causing a large cost increase or a decrease in lifespan. A layered body (6) is formed by alternately disposing negative electrode plates (20) and bag-like separators (3) in which a positive electrode plate (10) is stored. Each bag-like separator (3) is made of a porous synthetic resin and contains oil, and has a plate-shaped base part (31) and a plurality of ribs (32) protruding from a plate surface of the base part (31). The ribs (32) are arranged on the inside. A positive electrode current collection plate is a punched article consisting of a rolled plate made of a lead alloy. A lattice-shaped part in which a positive electrode mixture is held faces the plurality of ribs (32). A ratio (Ve / W) of the volume (Ve [cm3]) of a space formed by the base part (31), the plurality of ribs (32), and the lattice-shaped part in which the positive electrode mixture is held in one cell chamber to the mass (W [g]) of the positive electrode mixture is 0.150 or more.

Description

Flooded lead-acid battery and its manufacturing method

[0001] The present invention relates to a flooded lead-acid battery and a method for manufacturing the same.

[0002] A typical lead-acid battery, a flooded lead-acid battery, includes a battery case with a cell chamber, a plate assembly housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate assembly includes a stack of alternating positive and negative electrode plates and a separator disposed between the positive and negative electrode plates. The positive electrode plate includes a positive electrode current collector plate with a grid-like portion and a positive electrode mixture (a mixture containing a positive electrode active material) held in the grid-like portion, with a layer of the positive electrode mixture formed on both plate surfaces of the grid-like portion. The negative electrode plate includes a negative electrode current collector plate with a grid-like portion and a negative electrode mixture (a mixture containing a negative electrode active material) held in the grid-like portion, with a layer of the negative electrode mixture formed on both plate surfaces of the grid-like portion.

[0003] The positive electrode plate includes a positive electrode current collector plate with a grid-shaped portion, a positive electrode lug protruding upward from the grid-shaped portion in the vertical direction of the battery case, and a positive electrode mixture (a mixture containing a positive electrode active material) held in the grid-shaped portion. The negative electrode plate includes a negative electrode current collector plate with a grid-shaped portion, a negative electrode lug protruding upward from the grid-shaped portion in the vertical direction of the battery case, and a negative electrode mixture held in the grid-shaped portion. The positive electrode lug is positioned offset to one side from the center of the width of the grid-shaped portion (a direction perpendicular to both the vertical direction of the battery case and the stacking direction of the stack). The negative electrode lug is positioned offset to the other side from the center of the width of the grid-shaped portion. The plate assembly further includes a positive electrode strap and a negative electrode strap connecting the lugs of the multiple positive and negative electrode plates, respectively. Dilute sulfuric acid is used as the electrolyte. Such flooded lead-acid batteries are widely used in automobile batteries and other applications.

[0004] In many automotive lead-acid batteries, the positive electrode current collector plate is made of a rolled plate made of a calcium (Ca)-based lead alloy, processed by an expanding or punching method (expanded product, punched product). This is because this method allows for continuous production of the current collector plate, which is superior in productivity and cost compared to casting. However, in the case of expanded and punched positive electrode current collector plates made of a rolled plate made of a lead alloy, it is known that the positive electrode plate experiences elongation of the grid-like portion due to corrosion (so-called "growth") under high-temperature overcharge conditions. Therefore, using a punched positive electrode current collector plate, in which the grid-like portion is surrounded on all four sides by a frame, is more advantageous as a countermeasure against growth than an expanded positive electrode current collector plate because of its higher strength.

[0005] Lead-acid batteries, on the other hand, are classified by battery size and performance rank. Performance rank is calculated as "√(reserve capacity (RC) × cold cranking amperes (CCA)) / 2.8" and is one of the indicators used to compare the performance of lead-acid batteries. To improve this performance rank, it is necessary to increase the RC and / or CCA values. RC is the time (in minutes) required for a fully charged battery to reach a terminal voltage of 10.5 V when continuously discharged at a constant current of 25 A at 25°C ± 2°C. CCA is the maximum discharge current at which a battery can be discharged at a constant current of -18°C and maintain a battery voltage of 7.2 V or higher after 30 seconds.

[0006] To increase CCA, it is important to reduce electrical resistance. In this regard, Patent Documents 1 and 2 describe the relationship between the oil content of an oil-containing separator and its electrical resistance. Patent Document 1 also describes the following: One method for preventing a decrease in the oxidation resistance of a ribbed separator is to incorporate mineral oil into the separator. This method allows the inner and outer surfaces of the separator to be coated with oil, thereby protecting the surface of the polyolefin resin, which is vulnerable to oxidative environments, and slowing the progression of oxidative degradation.

[0007] Typically, mineral oil is used as a plasticizer in the extrusion molding raw material mixture, and then, during the process of extracting and removing the plasticizer (mineral oil) using an organic solvent, not all of the plasticizer is removed, leaving a certain amount remaining in the sheet. To improve oxidation resistance by incorporating mineral oil, the mineral oil content must be 5 to 30 mass% relative to the mass of the separator. A content of less than 5 mass% does not provide the ribbed separator with sufficient oxidation resistance for use as a lead-acid battery separator. Furthermore, a content of more than 30 mass% increases the proportion of pore space (voids) filled by the oil, resulting in increased electrical resistance and contamination of the battery container due to oil leaching into the dilute sulfuric acid electrolyte. In this case, the mineral oil functions not only as a plasticizer but also as a pore-forming agent and oxidation resistance imparting agent.

[0008] Patent Document 2 describes the following: The oil content in the separator is, for example, 10% by mass or more, and preferably 13% by mass or more. When the oil content is in this range, it is easy to ensure an excellent high-temperature overcharge life. The oil content in the separator is, for example, 20% by mass or less, preferably 18.0% by mass or less, and more preferably 17.5% by mass or less. When the oil content is in this range, the separator has low resistance. The evaluation was performed by a large-current discharge test in a low-temperature environment.

[0009] Patent Documents 1 and 2 do not mention improving the performance rank by increasing the RC, and no such mention is found in other documents. Furthermore, Patent Document 1 mentions that the separator is processed into a bag-like shape and used to house the anode or cathode plates, and Patent Document 2 mentions that each unformed negative electrode plate is housed in a bag-like separator, and an electrode plate group is formed with seven unformed negative electrode plates and six unformed positive electrode plates per cell.

[0010] Japanese Patent Publication No. 2001-338631 WO2020 / 066808 Pamphlet

[0011] An object of the present invention is to improve the performance rank of flooded lead-acid batteries by increasing RC without incurring a significant increase in cost or a decrease in lifespan.

[0012] The present inventors focused on the relationship between RC and separator. Generally, to increase the RC obtained as a result of a discharge test at a current lower than that of CCA, it is necessary to increase the amount of active material in the positive and negative electrodes or reduce the density. However, increasing the amount of active material increases weight and cost, while reducing the density of the active material reduces the lifespan. Increasing the RC without incurring these disadvantages is important for enhancing product value. As a result of extensive research, the present inventors discovered that when a stack is produced by encasing positive electrode plates in a pouch-shaped separator, the relationship between the volume of the electrolyte held in the pouch-shaped separator and the amount of positive electrode active material significantly affects the RC utilization rate (discharge capacity in the RC test / theoretical capacity of the positive electrode active material).

[0013] A first aspect of the present invention based on the above findings is a flooded lead-acid battery having the following configurations (1) to (4): (1) A battery case having a cell chamber, a plate assembly housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate assembly has a stack formed by alternately arranging a plurality of positive and negative plates, with separators disposed between them, and by alternately arranging the negative plates and the bag-shaped separators housing the positive plates. The positive plate has a positive current collector plate including a grid portion, a positive electrode lug protruding upward from the grid portion in the vertical direction of the battery case, and a positive electrode mixture (a mixture containing a positive electrode active material) held in the grid portion. The negative plate has a negative current collector plate including a grid portion, a negative electrode lug protruding upward from the grid portion in the vertical direction of the battery case, and a negative electrode mixture (a mixture containing a negative electrode active material) held in the grid portion. The positive electrode lug is positioned at a position offset to one side from the center of the width direction of the lattice portion (a direction perpendicular to both the up-and-down direction of the battery case and the stacking direction of the laminate), and the negative electrode lug is positioned at a position offset to the other side from the center of the width direction of the lattice portion. The electrode plate group further has a positive electrode strap connecting multiple positive electrode lugs and a negative electrode strap connecting multiple negative electrode lugs. (2) The bag-shaped separator is made of a porous synthetic resin and contains oil, and has a plate-shaped base and multiple ribs protruding from the plate surface of the base, with the ribs positioned on the inside. (3) The positive electrode current collector plate is an expanded or punched product made of a rolled plate made of a lead alloy, and the lattice portion holding the positive electrode mixture faces the multiple ribs. (4) The volume (Ve [cm 3 ] of the space formed by the base portion, the plurality of ribs, and the lattice portion in which the positive electrode mixture is held in one of the cell chambers 3 The ratio (Ve / W) of the mass of the positive electrode mixture (W [g]) to the mass of the positive electrode mixture (Ve / W) is 0.150 or more.

[0014] A second aspect of the present invention based on the above findings is a method for manufacturing a flooded lead-acid battery having the above configurations (1) to (3), and has the following configuration (5): (5) In one of the cell chambers, a volume (Ve [cm ]) of a space formed by the base portion, the plurality of ribs, and the grid portion in which the positive electrode mixture is held is3 The ribs of the pouch-shaped separator are designed so that the ratio (Ve / W) of the mass of the positive electrode mixture (W [g]) to the mass of the positive electrode mixture (Ve / W) is 0.150 or more.

[0015] According to the present invention, it is possible to increase the RC and improve the performance rank of flooded lead-acid batteries without incurring a significant increase in cost or a shortened lifespan.

[0016] 2 is a diagram illustrating a flooded lead-acid battery according to an embodiment, showing a state in which a lid is removed from a battery case; FIG. 3 is a partial cross-sectional view of a flooded lead-acid battery according to an embodiment; FIG. 4 is a plan cross-sectional view of a laminate constituting a flooded lead-acid battery according to an embodiment, corresponding to the A-A cross-sectional view of FIG.

[0017] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the following embodiments, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention.

[0018] [Overall Battery Configuration] As shown in FIG. 1 , the flooded lead-acid battery of this embodiment includes a monoblock-type battery case 1, a lid (not shown), and six electrode plate groups 2. The battery case 1 is rectangular and has a pair of first walls 11 formed on a pair of long sides of a rectangular bottom surface and a pair of second walls 12 formed on a pair of short sides. The interior of the battery case 1 is divided into six cell chambers 4 by five partition walls 13 parallel to the second walls 12. One electrode plate group 2 is disposed in each of the six cell chambers 4, and each cell chamber 4 is filled with an electrolyte. The electrolyte is dilute sulfuric acid with a specific gravity of 1.28 to 1.30 (at 20°C). Although not shown, the tops of all the cell chambers 4 are closed by fastening a lid to the battery case 1. As shown in FIG. 1 , the arrangement direction of the cell chambers 4 is the X direction, and the direction perpendicular thereto is the Y direction.

[0019] 2, the electrode plate group 2 has a stack 6, which is composed of a plurality of alternately arranged positive electrode plates 10 and negative electrode plates 20, and separators 30 arranged between the positive electrode plates 10 and the negative electrode plates 20. The number of positive electrode plates 10 constituting the stack 6 may be the same as the number of negative electrode plates 20, or may be greater than the number of negative electrode plates 20. In this example, there is one less positive electrode plate 10 than negative electrode plate 20.

[0020] The positive electrode plate 10 is composed of a positive electrode current collector and a positive electrode mixture (a mixture containing a positive electrode active material). The positive electrode current collector has a rectangular grid portion and a tab protruding from one side of the rectangle forming the grid portion, and the positive electrode mixture is held in the grid portion. In FIG. 2 , the grid portion holding the positive electrode mixture is indicated by reference numeral 101, and the tab of the positive electrode plate 10 is indicated by reference numeral 120. The tab 120 of the positive electrode plate 10 is positioned offset to one side from the center of the width direction of the grid portion (the direction perpendicular to the paper surface of FIG. 2 ). The positive electrode plate 10 will be described in detail later.

[0021] The negative electrode plate 20 is composed of a negative electrode current collector and a negative electrode mixture (a mixture containing a negative electrode active material). The negative electrode current collector has a rectangular lattice portion and a tab protruding from one side of the rectangle forming the lattice portion, and the negative electrode mixture is held in the lattice portion. In FIG. 2 , the lattice portion holding the negative electrode mixture is indicated by reference numeral 201, and the tab of the negative electrode plate 20 is indicated by reference numeral 220. The tab 220 of the negative electrode plate 20 is positioned at a position offset from the center of the lattice portion in the width direction (the direction perpendicular to the paper surface of FIG. 2 ). The negative electrode plate 20 will be described in detail later.

[0022] 3, the stack 6 is formed by alternately arranging bag-shaped separators 3 housing positive electrode plates 10 and negative electrode plates 20. The bag-shaped separators 3 are made of porous polyethylene and contain oil at a ratio of 5% by mass to 20% by mass. The bag-shaped separators 3 have a pair of opposing plate-shaped base portions 31 and a plurality of ribs protruding from the plate surfaces of the base portions 31, with the ribs 32 disposed on the inside. For example, the thickness of the base portions 31 is 0.15 mm to 0.25 mm, the protruding height t of the ribs 32 is 0.4 mm to 0.6 mm, the width of the ribs 32 is 0.1 mm to 0.4 mm, and the intervals between the ribs 32 are 2 mm to 10 mm.

[0023] The bag-shaped separator 3 is made by cutting a rectangular film of a predetermined length from a strip of porous polyethylene film having a plurality of ribs 32 protruding from the plate surface of a base portion 31, folding the film in half with the rib 32 side facing inward, and welding the left and right ends together. Therefore, by alternately arranging the bag-shaped separators 3 containing the positive electrode plates 10 and the negative electrode plates 20, the pair of separators 30 constituting the bag-shaped separator 3 are arranged between the positive electrode plates 10 and the negative electrode plates 20. In other words, the bag-shaped separator 3 is closed on the bottom side of the battery case of the two separators 30 and on both widthwise sides of the positive electrode plates to be housed, and is open on the top side of the battery case.

[0024] The positive electrode current collector plate is a punched product made of a rolled plate made of a lead alloy, and a lattice portion 101 holding the positive electrode mixture faces a plurality of ribs 32. All of the ribs 32 are in contact with the lattice portion 101 holding the positive electrode mixture, but are not bent. The volume of the space formed by the base portion 31, all of the ribs 32, and the lattice portion 101 holding the positive electrode mixture in one cell chamber 4 (Ve [cm 3 The ratio (Ve / W) of the mass (W [g]) of the positive electrode mixture to the mass (W [g]) of the positive electrode mixture is 0.150 or more. In other words, when one cell chamber 4 contains N positive electrode plates 10 (the number of "bag-like separators 3 containing positive electrode plates 10" constituting the stack 6 is N), an electrolyte retention space with a volume of "Ve / N" exists within one bag-like separator 3. Furthermore, W [g] is N times the mass of the positive electrode mixture contained in one positive electrode plate 10.

[0025] The stack 6 is housed in the cell chamber 4 with the stacking direction aligned along the X direction and the plate surfaces of the positive and negative plates 10 and 20 aligned along the vertical direction of the cell chamber 4. Each plate pack 2 further includes a positive strap 71, a negative strap 72, and a positive intermediate electrode post 71a and a negative intermediate electrode post 72a rising from the positive strap 71 and the negative strap 72, respectively. The positive strap 71 and the negative strap 72 connect the lugs 120 of the positive plates 10 and the lugs 220 of the negative plates 20 constituting the stack 6 at different positions in the width direction of the positive plates 10 and the negative plate 20 (the direction that corresponds to the Y direction when placed in the cell chamber). The plate packs 2 arranged in the cell chambers at both ends in the cell arrangement direction each include a positive electrode post 8 and a negative electrode post 9 that serve as external terminals.

[0026] The positive electrode intermediate pole 71a and the negative electrode intermediate pole 72a of adjacent cell chambers 4 are resistance-welded to electrically connect adjacent cells in series. The positive electrode pole 8 and the negative electrode pole 9 are respectively attached to the positive electrode strap 71 and the negative electrode strap 72 via small pieces 71b and 72b. The positive electrode pole 8 and the negative electrode pole 9 penetrate the lid and are exposed to the outside.

[0027] [Regarding the Positive and Negative Electrodes] [Method for Manufacturing the Positive and Negative Electrodes] The positive and negative electrode mixtures are filled into the openings of each grid portion and are also present in layers on both surfaces of the grid portion. The positive and negative electrode mixtures are formed on the grid portion of each current collector plate, for example, as follows: First, necessary additives (polypropylene fiber, polyethylene fiber, conductive carbon, etc.) are added to lead powder and mixed by dry mixing. Water is then added and kneaded to obtain a water paste. Sulfuric acid is then added to this water paste and kneaded to produce a positive electrode paste and a negative electrode paste. Since organic shrink-preventing agents, such as lignin, which are often used as negative electrode additives, are water-soluble, they may be added simultaneously with the water. Next, the resulting positive and negative electrode pastes are filled into the openings of each grid portion and then subjected to preheating, aging, and drying processes to obtain pre-chemical positive and negative electrode plates. Furthermore, by assembling a flooded lead-acid battery using these materials and then carrying out chemical formation, a positive electrode mixture and a negative electrode mixture are formed in each grid portion.

[0028] [Positive current collector plate] The positive current collector plate constituting the positive electrode plate 10 is an expanded or punched product made of a rolled plate made of a lead alloy (Pb—Ca-based alloy). The thickness of the positive current collector plate is, for example, 0.7 mm or more and 1.1 mm or less. [Negative current collector plate] The negative current collector plate constituting the negative electrode plate 20 is formed by a continuous casting method using a lead alloy (such as a Pb—Ca—Sn-based alloy), or is an expanded or punched product made of a rolled plate made of a lead alloy. The thickness of the negative current collector plate is, for example, 0.8 mm or more and 1.1 mm or less.

[0029] [Actions and Effects] In the flooded lead-acid battery of the above embodiment, the ratio (Ve / W) in one cell chamber 4 is 0.150 or greater, thereby increasing the RC and improving the performance rank of the flooded lead-acid battery without increasing costs or shortening the battery life, compared to when the ratio (Ve / W) is less than 0.150. If the ratio (Ve / W) is too large, the mass (W) of the positive electrode mixture may be too small, making it impossible to obtain the required RC capacity. Therefore, the ratio (Ve / W) is preferably 0.150 or greater and 0.350 or less. A more preferred range for the ratio (Ve / W) is 0.160 or greater and 0.300 or less, and an especially preferred range is 0.190 or greater and 0.260 or less.

[0030] Furthermore, by containing oil in a proportion of 5% by mass or more and 20% by mass or less in pouch-shaped separator 3, the high-temperature overcharge durability is excellent, and the resistance value is kept low, resulting in a good CCA. If the oil content of pouch-shaped separator 3 is less than 5% by mass, the high-temperature overcharge durability may be insufficient, while if it exceeds 20% by mass, the resistance value may be so high that the standard CCA value may not be achieved. A more preferable range for the oil content of the pouch-shaped separator is 10% by mass or more and 15% by mass or less.

[0031] The flooded lead-acid battery of the above embodiment is manufactured by a method in which the ribs 32 of the bag-shaped separator 3 are designed so that the above-mentioned ratio (Ve / W) in one cell chamber 4 is 0.150 or more, thereby making it possible to increase the RC and improve the performance rank of the flooded lead-acid battery without increasing the mass of the positive electrode mixture or decreasing the density, that is, without incurring an increase in cost or a decrease in lifespan.

[0032] [Fabrication of Test Batteries] Samples 1-1 to 1-7 and 2-1 to 2-7 were fabricated as flooded lead-acid batteries having the same structure as the flooded lead-acid battery of the embodiment. However, the cross-sectional shape of the rib 32 was rectangular rather than trapezoidal as shown in Figure 3. Samples 1-1 to 1-7 were Q-size flooded lead-acid batteries with a nominal voltage of 12 V, and all had the same configuration except for at least one of the protrusion dimension t (mm) of the rib 32 of the bag-shaped separator 3 from the base portion 31, the number of ribs 32, the width (mm) of the rib 32, and the mass W of the positive electrode mixture, as shown in Table 1.

[0033] The flooded lead-acid batteries of Samples No. 2-1 to No. 2-7 were medium-sized flooded lead-acid batteries with a nominal voltage of 12 V, and all had the same configuration except that at least one of the protrusion dimension t (mm) of the ribs 32 of the pouch-shaped separator 3 from the base portion 31, the number of ribs 32, the width (mm) of the ribs 32, and the mass W of the positive electrode mixture was changed as shown in Table 2. Also, Ve in Tables 1 and 2 is calculated by multiplying {(H-rib volume × number of ribs × 2) × number of positive electrodes} by cm 3 H is the value calculated by converting the area of ​​the grid part of the positive electrode plate into s (mm 2 ), where H is a volume value calculated by H = s × t × 2, the number of positive electrodes is 7 for No. 1-1 to No. 1-7 and 6 for No. 2-1 to No. 2-7, as described below, and W is a value obtained by multiplying the mass of the positive electrode mixture per positive electrode plate by the number of plates.

[0034] [No. 1-1 to No. 1-7] <Production of Positive Electrode Plates Before Chemical Forming> Positive electrode current collector plates were produced by performing a slab casting process, a rolling process, and a punching process in this order. First, a slab casting process was performed using the following method. A block of lead alloy containing 0.06 mass% Ca, 1.6 mass% Sn, 0.02 mass% Al, and the remainder being lead and unavoidable impurities was prepared and melted by heating to obtain a molten metal. This molten metal was poured between two opposing metal rolls and cooled by the metal rolls to obtain a lead alloy slab. Next, the obtained lead alloy slab was passed through a pair of upper and lower rolling rolls to perform a rolling process at a reduction ratio of 90%, obtaining a rolled sheet having a width of 320 mm and a thickness of 1.0 mm.

[0035] Next, the obtained rolled sheet was put into a press molding machine and punched in the thickness direction to obtain a positive electrode current collector plate with ears extending upward from the upper frame of the lattice-shaped portion. The dimensions of the lattice-shaped portion were 116.5 mm in the direction in which the ears extended (height), 137.0 mm in the direction perpendicular thereto (width), and 1.0 mm in thickness. Therefore, the area of ​​the lattice-shaped portion was 15960.5 mm. 2 The dimensions of the ears were 10 mm in width and 15 mm in height. The ears extended from between the center and the end of the lattice portion in the width direction. The lattice portion of the obtained positive electrode current collector plate was filled with a positive electrode paste prepared by a conventional method, and the plate was aged and dried by a conventional method to obtain a pre-chemical positive electrode plate (positive electrode filled plate).

[0036] <Production of Negative Electrode Plate Before Chemical Forming> A negative electrode current collector plate having a shape in which lugs extend upward from the upper frame of the lattice-shaped portion was obtained by continuous casting using a lead alloy containing 0.09% by mass of Ca, 0.4% by mass of Sn, 0.02% by mass of Al, and the remainder being lead and unavoidable impurities. The dimensions of the lattice-shaped portion were 115 mm in the direction in which the lugs extend (height), 135 mm in the direction perpendicular thereto (width), and 0.8 mm in thickness. The dimensions of the lugs were 10 mm in width and 15 mm in height. The lugs extended from between the center and end of the lattice-shaped portion in the width direction. The ribs of the lattice-shaped portion of the obtained negative electrode current collector plate were composed of 16 vertical ribs approximately perpendicular to the upper frame and 7 horizontal ribs approximately perpendicular to the vertical ribs.

[0037] The grid-shaped portion of the obtained negative electrode current collector plate was filled with 55 g of a negative electrode paste prepared by the following method, and then heat treatment before aging was performed at 400°C or 300°C. Next, the plate was aged at 40°C and a relative humidity of 90%, and then dried at 60°C to obtain a negative electrode filled plate (negative electrode plate before chemical conversion) for each sample. The negative electrode paste was prepared by adding water and sulfuric acid to lead powder and kneading them to obtain a water paste, and then adding acetylene black (AB) or ketjen black (KB) as conductive carbon to this water paste in a ratio of 0.2 parts by mass per 100 parts by mass of lead powder and kneading them.

[0038] <Preparation of Pre-Chemical Electrode Plate Assembly> A porous polyethylene separator with vertical ribs and an oil content of 5% by mass was prepared as a bag-shaped separator, with the vertical rib side facing inward. The protrusion distance t of the ribs 32 from the base portion 31, the number of ribs 32, and the width of the ribs 32 were as shown in Table 1. The dimensions of the base portion 31 were set so that the positive electrode packing plates No. 1-1 to No. 1-7 could be inserted into the bag-shaped separator with an appropriate gap. One positive electrode packing plate for each sample was placed in the bag-shaped separator. Seven positive electrode packing plate-containing bag-shaped separators and eight negative electrode packing plates were alternately stacked to produce six stacks for each sample. Next, a cast-on-strap (COS) casting machine was used to form straps, intermediate poles, and terminal poles on the positive electrode packing plates and negative electrode packing plates of the six stacks for each sample, thereby obtaining six electrode plate assemblies for each sample.

[0039] <Battery Assembly> Next, the six electrode plate groups obtained for each sample were placed into six cell chambers of a polypropylene monoblock battery case. Next, resistance welding of the intermediate electrode posts between adjacent cell chambers and heat welding of the battery case to the lid were performed using conventional methods. Next, an electrolyte consisting of dilute sulfuric acid with a specific gravity of 1.250 (converted at 20°C) was poured into each cell chamber through each of the inlet holes in the lid. Next, the inlet holes were sealed to assemble an unformed flooded lead-acid battery. Then, the battery case was formed using conventional methods to convert the positive and negative electrode filler plates into positive and negative plates, completing the flooded lead-acid battery. In this state, all of the tip surfaces of the ribs 32 within the bag-shaped separator were in contact with each of the positive electrode filler plates No. 1-1 to No. 1-7.

[0040] [No. 2-1 to No. 2-7] <Production of Positive Electrode Plates Before Chemical Forming> A rolled sheet obtained in the same manner as No. 1-1 to No. 1-7 was put into a press molding machine and punched in the thickness direction to obtain a positive electrode current collector plate with a shape in which tabs extend upward from the upper frame of the lattice-shaped portion. The dimensions of the lattice-shaped portion were 105.0 mm in the direction in which the tabs extend (height), 113.0 mm in the direction perpendicular thereto (width), and 1.0 mm in thickness. Therefore, the area of ​​the lattice-shaped portion was 11,865.0 mm. 2 The dimensions of the ears were 10 mm in width and 15 mm in height. The ears extended from between the center and the end of the lattice portion in the width direction. The lattice portion of the obtained positive electrode current collector plate was filled with a positive electrode paste prepared by a conventional method, and the plate was aged and dried by a conventional method to obtain a pre-chemical positive electrode plate (positive electrode filled plate).

[0041] <Production of Negative Electrode Plate Before Chemical Forming> A negative electrode current collector plate having a shape in which lugs extend upward from the upper frame of the lattice-shaped portion was obtained by continuous casting using a lead alloy containing 0.09% by mass of Ca, 0.4% by mass of Sn, 0.02% by mass of Al, and the remainder being lead and unavoidable impurities. The dimensions of the lattice-shaped portion were 100 mm in the direction in which the lugs extend (height), 100 mm in the direction perpendicular thereto (width), and 0.8 mm in thickness. The dimensions of the lugs were 10 mm in width and 15 mm in height. The lugs extended from between the center and end of the lattice-shaped portion in the width direction. The ribs of the lattice-shaped portion of the obtained negative electrode current collector plate were composed of 16 vertical ribs approximately perpendicular to the upper frame and 10 horizontal ribs approximately perpendicular to the vertical ribs.

[0042] The grid-shaped portion of the obtained negative electrode current collector plate was filled with 75 g of a negative electrode paste prepared by the following method, and then heat treatment before aging was performed at 400°C or 300°C. Next, the plate was aged at 40°C and a relative humidity of 90%, and then dried at 60°C to obtain a negative electrode plate (negative electrode filled plate) before chemical conversion. The negative electrode paste was prepared by adding water and sulfuric acid to lead powder and kneading them to obtain a water paste, and then adding acetylene black (AB) or ketjen black (KB) as conductive carbon to this water paste in a ratio of 0.2 parts by mass per 100 parts by mass of lead powder and kneading them together.

[0043] <Preparation of Electrode Plate Assembly Before Chemical Formation> A porous polyethylene separator with vertical ribs and an oil content of 5% by mass was formed into a bag-like separator 3 with the vertical rib side facing inward. The protrusion dimension t of the ribs 32 from the base portion 31, the number of ribs 32, and the width of the ribs 32 were as shown in Table 2. The dimensions of the base portion 31 were set so that the separator could be inserted into the bag-like separator with an appropriate gap. One positive electrode packing plate for each sample was placed in each bag-like separator. Six positive electrode packing plates and seven negative electrode packing plates were alternately stacked to produce six stacks for each sample. Next, a cast-on-strap (COS) casting machine was used to form straps, intermediate poles, and terminal poles on the positive electrode packing plates and negative electrode packing plates of the six stacks for each sample, thereby obtaining six electrode plate assemblies for each sample.

[0044] <Battery Assembly> Batteries were assembled in the same manner as Nos. 1-1 to 1-7, except that the dimensions of the battery containers used were changed to match the dimensions of the plate assemblies No. 2-1 to No. 2-7. Then, the battery containers were formed in the usual manner to convert the positive and negative electrode packing plates into positive and negative plates, completing flooded lead-acid batteries. In this state, all of the tip surfaces of the ribs 32 within the separator bag were in contact with the positive electrode packing plates No. 2-1 to No. 2-7.

[0045] [Reserve Capacity Test] Using each sample of flooded lead-acid battery obtained, a test was conducted in a 25°C water bath to 10.5 V at 25 A according to the method specified in "10.2 Reserve Capacity (RCe) Test" of "JIS D 5301." The discharge duration was recorded in minutes, and the effective reserve capacity (RCe: unit: minutes) was calculated. The calculated RCe (minutes) was then used to calculate the discharge capacity (Ah). The calculated discharge capacity (Ah) was divided by the "theoretical capacity of the positive electrode active material per cell" to calculate the reserve capacity utilization rate (hereinafter also referred to as "RC utilization rate" or simply "utilization rate").

[0046] These results are shown in Tables 1 and 2 together with the separator configuration and ratio (Ve / W).

[0047]

[0048]

[0049] As can be seen from the results in Table 1, for the Q size, flooded lead-acid batteries No. 1-3 to No. 1-7, which have a ratio (Ve / W) of 0.150 or greater, have an RC utilization rate of 37% or greater, while flooded lead-acid batteries No. 1-1 and No. 1-2, which have a ratio (Ve / W) of less than 0.150, have an RC utilization rate of approximately 35%. Furthermore, while a difference in utilization rate between the standard battery No. 1-2 and the battery No. 1-3 to No. 1-7, which have a ratio (Ve / W) of 0.150 or greater, is considered to meet the required regulations, the difference in utilization rate between the battery No. 1-2 and the battery No. 1-3 to No. 1-7 is 2.3% or greater.

[0050] Furthermore, as can be seen from the results in Table 2, for the M size, flooded lead-acid batteries No. 2-3 to No. 2-7, which have a ratio (Ve / W) of 0.150 or greater, have an RC utilization rate of 29.5% or greater, while flooded lead-acid batteries No. 2-1 and No. 2-2, which have a ratio (Ve / W) of less than 0.150, have an RC utilization rate of less than 27%. Furthermore, while a difference in utilization rate from the reference battery No. 2-2 of 2.0 or greater is considered to satisfy the required regulations, flooded lead-acid batteries No. 2-3 to No. 2-7, which have a ratio (Ve / W) of 0.150 or greater, have a difference in utilization rate from No. 2-2 of 2.9% or greater.

[0051] From the above, the following can be seen. First, by increasing the volume Ve, that is, by increasing the ratio (Ve / W), it is possible to increase the utilization rate without increasing the mass of the active material or decreasing the density of the active material compared to the reference product. Second, by making the ratio (Ve / W) 0.150 or more, it is possible to satisfy the required regulations.

[0052] [Evaluation of Differences in Oil Content] <Battery Assembly> Flooded lead-acid batteries No. 1-11 to No. 1-15 were fabricated by assembling batteries in the same manner as No. 1-3, except that pouch-shaped separators 3 with oil contents of 3 mass%, 10 mass%, 15 mass%, 20 mass%, and 25 mass% were used. Flooded lead-acid batteries No. 2-11 to No. 2-15 were fabricated by assembling batteries in the same manner as No. 2-4, except that pouch-shaped separators 3 with oil contents of 3 mass%, 10 mass%, 15 mass%, 20 mass%, and 25 mass% were used.

[0053] <Test Method> First, in accordance with "JIS D 5301," flooded lead-acid batteries No. 1-3, No. 1-11 to No. 1-15 were discharged at 590 A at a battery temperature of -18°C, and flooded lead-acid batteries No. 2-4, No. 2-11 to No. 2-15 were discharged at 310 A at a battery temperature of -18°C. The voltage at 30 seconds was measured. Next, to evaluate high-temperature overcharge durability, a light-load life test according to "JIS D 5301" was conducted. To accelerate the corrosion rate, the test temperature was changed from 41°C to 75°C, and the discharge time was changed from 240 seconds to 60 seconds. In other words, one cycle consisted of a 60-second discharge at a discharge current of 25 A at 75°C, followed by a 10-minute charge at a charge voltage of 14.8 V. After repeating this cycle for 480 times, a 30-second discharge was performed to determine the life span at 590 A for Nos. 1-3, 1-11 to 1-15, and at 310 A for Nos. 2-4, 2-11 to 2-15. The number of cycles at which the voltage at 30 seconds dropped to 7.2 V was recorded as the high-temperature overcharge life span, or, if the current showed an increasing trend during the 10-minute charge, suggesting a short circuit, the number of cycles at that point.

[0054] These results are shown in Tables 3 and 4. In Table 3, the high-temperature overcharge life is shown as a relative value with the value (number of cycles) of Nos. 1-3 set to 100, and in Table 4, the high-temperature overcharge life is shown as a relative value with the value (number of cycles) of Nos. 2-4 set to 100.

[0055]

[0056]

[0057] As can be seen from the results in Table 3, the flooded lead-acid batteries No. 1-3 and No. 1-11 to No. 1-14, which had an oil content of 3% by mass or more and 20% by mass or less in the pouch-shaped separator, achieved a voltage at 30 seconds of 7.2 V or more, which is the CCA standard value, but the flooded lead-acid battery No. 1-15, which had an oil content of 25% by mass, achieved a voltage at 30 seconds of 6.8 V, which is less than the standard value. Furthermore, the flooded lead-acid batteries No. 1-3 and No. 1-12 to No. 1-15, which had an oil content of 5% by mass or more and 25% by mass or less in the pouch-shaped separator, had a relative value of 100 or more for the high-temperature overcharge life, whereas the flooded lead-acid battery No. 1-11, which had an oil content of 3% by mass in the pouch-shaped separator, had a relative value of 95 (less than 100).

[0058] As can be seen from the results in Table 4, the flooded lead-acid batteries No. 2-4 and No. 2-11 to No. 2-14, which had an oil content of 3% by mass or more and 20% by mass or less in the pouch-shaped separator, achieved a voltage at 30 seconds of 7.2 V or more, which is the CCA standard value, but the flooded lead-acid battery No. 2-15, which had an oil content of 25% by mass, achieved a voltage at 30 seconds of 7.1 V, which is less than the standard value. Furthermore, the flooded lead-acid batteries No. 2-4 and No. 2-12 to No. 2-15, which had an oil content of 5% by mass or more and 25% by mass or less in the pouch-shaped separator, had a relative value of 100 or more for the high-temperature overcharge life, whereas the flooded lead-acid battery No. 2-11, which had an oil content of 3% by mass in the pouch-shaped separator, had a relative value of 93 (less than 100).

[0059] As can be seen from the above, in a flooded lead-acid battery with a high RC, in which the ratio (Ve / W) is 0.150 or more, by setting the oil content of the bag-shaped separator to 5 mass% or more and 20 mass% or less, it is possible to improve both the CCA and the high-temperature overcharge life.

[0060] DESCRIPTION OF SYMBOLS 1 Battery case 11 Battery case first wall 12 Battery case second wall 13 Battery case partition wall 2 Plate group 3 Bag-shaped separator 30 Separator 31 Base portion 32 Rib 4 Cell chamber 6 Stacked body 10 Positive electrode plate 101 Lattice portion of positive electrode current collector plate in a state where a positive electrode mixture is held 120 Ear portion of positive electrode current collector plate 20 Negative electrode plate 201 Lattice portion of negative electrode current collector plate in a state where a negative electrode mixture is held 220 Ear portion of negative electrode current collector plate 71 Positive electrode strap 72 Negative electrode strap 71a Positive electrode intermediate electrode post 72a Negative electrode intermediate electrode post 8 Positive electrode terminal 9 Negative electrode terminal

Claims

1. A battery container having a cell chamber, a group of electrodes housed in the cell chamber, and an electrolyte injected into the cell chamber, wherein the group of electrodes has a laminate formed by alternately arranging a separator between a plurality of alternatingly arranged positive and negative plates, and by alternately arranging the bag-shaped separators in which the positive plates are housed and the negative plates, wherein the positive plates have a positive current collector plate including a lattice portion, a positive ear protruding from the lattice portion above the battery container in the vertical direction, and a positive electrode mixture held by the lattice portion, wherein the negative plate has a negative current collector plate including a lattice portion, a negative electrode ear protruding from the lattice portion above the battery container in the vertical direction, and a negative electrode mixture held by the lattice portion, wherein the positive electrode ear is positioned in one direction from the center of the lattice portion in the width direction, and the negative electrode ear is positioned in the other direction from the center of the lattice portion in the width direction, the electrode plate group further has a positive electrode strap connecting a plurality of the positive electrode lugs and a negative electrode strap connecting a plurality of the negative electrode lugs, the bag-shaped separator is made of a porous synthetic resin containing oil, and has a plate-shaped base portion and a plurality of ribs protruding from the plate surface of the base portion, the ribs being disposed on the inside, the positive electrode current collector plate is an expanded product or a punched product made of a rolled plate made of a lead alloy, the lattice portion holding the positive electrode mixture faces the plurality of ribs, and the volume (Ve [cm] of a space formed by the base portion, the plurality of ribs, and the lattice portion holding the positive electrode mixture in one of the cell chambers is 3 ]) to the mass (W [g]) of the positive electrode mixture, V / W being 0.150 or more.

2. A flooded lead-acid battery according to claim 1, wherein said positive electrode current collector plate is a stamped product made of a rolled plate made of a lead alloy.

3. A flooded lead-acid battery as claimed in claim 1 or 2, wherein the oil content of said pouch-shaped separator is between 5% by mass and 20% by mass.

4. A battery case having a cell chamber, a group of electrodes housed in the cell chamber, and an electrolyte injected into the cell chamber, wherein the group of electrodes has a laminate formed by alternately arranging a separator between a plurality of alternatingly arranged positive and negative plates, and by alternately arranging the bag-shaped separators in which the positive plates are housed and the negative plates, wherein the positive plates have a positive current collector including a lattice portion, a positive ear protruding from the lattice portion above the battery case in the vertical direction, and a positive electrode mixture held by the lattice portion, wherein the negative plates have a negative current collector including a lattice portion, a negative ear protruding from the lattice portion above the battery case in the vertical direction, and a negative electrode mixture held by the lattice portion, wherein the positive electrode ear is positioned in one direction from the center of the lattice portion in the width direction, and the negative electrode ear is positioned in the other direction from the center of the lattice portion in the width direction, a manufacturing method for a flooded lead-acid battery, the method comprising: the electrode plate group further comprising a positive electrode strap connecting a plurality of the positive electrode lugs and a negative electrode strap connecting a plurality of the negative electrode lugs; the bag-shaped separator is made of a porous synthetic resin containing oil, and has a plate-shaped base portion and a plurality of ribs protruding from the plate surface of the base portion, the ribs being disposed on the inside; the positive electrode current collector plate is an expanded or punched product made of a rolled plate made of a lead alloy, and the lattice portion holding the positive electrode mixture faces the plurality of ribs; and 3 the ribs of the pouch-shaped separator are designed so that the ratio (Ve / W) of the mass of the positive electrode mixture (W [g]) to the mass of the positive electrode mixture (Ve / W) is 0.150 or more.

5. The method of manufacturing a flooded lead-acid battery according to claim 4, wherein the positive electrode current collector plate is a stamped product made of a rolled plate made of a lead alloy.

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