Flooded lead-acid battery and its manufacturing method

Abstract

To improve a performance rank of a liquid-type lead storage battery by increasing RC without causing large cost increase or decrease in lifespan.SOLUTION: A layered body 6 is formed by alternately disposing negative electrode plates 20 and bag-like separators 3 in each of 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 being arranged on the inside. A positive electrode current collector 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 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 mass (W [g]) of the positive electrode mixture is 0.150 or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A flooded lead-acid battery, which is a typical lead-acid battery, includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate group has a laminate including a plurality of alternatingly arranged positive and negative plate plates and separators arranged between the positive and negative plate plates. The positive electrode plate has a positive electrode current collector including a lattice portion, a positive electrode mixture (a mixture containing a positive electrode active material) held by the lattice portion, and a layer of the positive electrode mixture is formed on both plate surfaces of the lattice portion.The negative electrode plate has a negative electrode current collector including a lattice portion, and a negative electrode mixture (a mixture containing a negative electrode active material) held by the lattice portion, and a layer of the negative electrode mixture is formed on both plate surfaces of the lattice portion.

[0003] The positive electrode plate has a positive electrode current collector including a lattice portion, a positive electrode lug protruding upward from the lattice portion in the vertical direction of the battery case, and a positive electrode mixture (a mixture containing a positive electrode active material) held by the lattice portion, and the negative electrode plate has a negative electrode current collector including a lattice portion, a negative electrode lug protruding upward from the lattice portion in the vertical direction of the battery case, and a negative electrode mixture held by the lattice portion. The positive electrode lug is disposed at a position offset to one side from the center of the width direction of the grid portion (a direction perpendicular to both the up-down direction of the battery case and the stacking direction of the stack), and the negative electrode lug is disposed at a position offset to the other side from the center of the width direction of the grid portion. The electrode plate group further has a positive electrode strap and a negative electrode strap that respectively connect the lugs of the multiple positive and negative electrode plates. Dilute sulfuric acid is used as the electrolyte. Such flooded lead-acid batteries are widely used as automobile batteries and the like.

[0004] In many cases, the positive current collector plate used in lead-acid batteries for automobiles is a rolled plate made of calcium (Ca)-based lead alloy that has been processed by the expanding or punching method (expanded product, punched product).The reason for this is that this method allows for continuous production of current collector plates, which is superior in terms of productivity and cost compared to the casting method. However, in the case of an expanded product or a punched product in which the positive electrode current collector plate is made of a rolled plate of a lead alloy, it is known that the grid-shaped portion of the positive electrode plate will expand due to corrosion (so-called "growth") in a high-temperature overcharge environment. Therefore, it is more advantageous to use a punched product in which the grid-shaped portion is surrounded by a frame on all four sides as the positive electrode current collector plate than an expanded product in terms of growth prevention because of its higher strength.

[0005] Meanwhile, lead-acid batteries are classified by product type, not only by battery size, but also by performance rank. The performance rank is a value calculated by "√(reserve capacity (RC) × cold cranking amperes (CCA)) / 2.8" and is one of the indices for comparing the performance of lead-acid batteries. To improve this performance rank, it is necessary to increase the RC value and / or the CCA value.

[0006] RC is the duration (in minutes) until the terminal voltage reaches 10.5V when a fully charged storage battery is continuously discharged at a constant current of 25A at 25℃±2℃. CCA is the maximum discharge current value at which the battery voltage can be maintained at 7.2V or higher after 30 seconds of constant current discharge in a -18℃ environment. In order to increase the CCA, it is important to reduce the 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.

[0007] Patent Document 1 contains the following description: One method for preventing the oxidation resistance of ribbed separators from decreasing is to incorporate mineral oil into the separator, which can cover the inner and outer surfaces of the separator with oil, protecting the surface of the polyolefin resin, which is vulnerable to oxidizing atmospheres, and slowing down the progression of oxidative degradation.

[0008] Typically, mineral oil is used in advance as a plasticizer to be mixed into the raw material mixture for extrusion molding, and in the process of extracting and removing the plasticizer (mineral oil) using an organic solvent, not all of the plasticizer is removed, but a certain amount is left in the sheet. In order to improve oxidation resistance by adding mineral oil, the mineral oil must be present in an amount of 5 to 30 mass% relative to the mass of the separator. If the amount is less than 5 mass%, the ribbed separator cannot be provided with sufficient oxidation resistance as a separator for a lead-acid battery. If the amount is more than 30 mass%, the oil will fill a large proportion of the micropore space (voids), causing an increase in electrical resistance, and the oil will leach into the dilute sulfuric acid electrolyte, causing contamination inside the battery container. In this case, the mineral oil not only functions as a plasticizer, but also as a micropore former and an oxidation resistance imparting agent.

[0009] Patent Document 2 contains the following description: 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 is performed by a large current discharge test in a low-temperature environment.

[0010] Patent Documents 1 and 2 do not describe improving the performance rank by increasing the RC, and no such description is found in other documents. Furthermore, Patent Document 1 describes that the separator is processed into a bag shape to house an anode plate or a cathode plate, and Patent Document 2 describes that each unformed negative plate is housed in a bag-shaped separator, and an electrode plate group is formed with seven unformed negative plates and six unformed positive plates per cell. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2001-338631 A [Patent Document 2] WO2020 / 066808 Brochure Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to increase the RC and improve the performance rank of flooded lead-acid batteries without incurring a significant increase in cost or a decrease in lifespan. [Means for solving the problem]

[0013] The present inventors focused on the relationship between RC and the separator. In general, in order to increase the RC obtained as a result of a discharge test at a current smaller than that of CCA, it is necessary to increase the amount of active material in the positive and negative electrodes or to decrease the density. However, increasing the amount of active material has the disadvantage of increasing weight and cost, and decreasing the density of the active material has the disadvantage of reducing the life. In order to increase the product value, it is important to increase the RC without causing such disadvantages.

[0014] As a result of intensive research, the present inventors have found that when a laminate is produced by storing positive electrode plates in a bag-shaped separator, the relationship between the volume of the electrolyte held in the bag-shaped separator and the amount of the positive electrode active material has a significant effect on the RC utilization rate (discharge capacity in an RC test / theoretical capacity of the positive electrode active material).

[0015] 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 group housed in the cell chamber, and an electrolyte injected into the cell chamber. The plate group has a laminate formed by alternately arranging a separator between a plurality of alternatingly arranged positive and negative plates, and alternately arranging the bag-shaped separator housing the positive plate and the negative plate. The positive plate has a positive current collector plate including a lattice-shaped portion, a positive ear portion protruding from the lattice-shaped portion to the upper side in the vertical direction of the battery case, and a positive electrode mixture (a mixture containing a positive electrode active material) held by the lattice-shaped portion. The negative plate has a negative current collector plate including a lattice-shaped portion, a negative electrode ear portion protruding from the lattice-shaped portion to the upper side in the vertical direction of the battery case, and a negative electrode mixture (a mixture containing a negative electrode active material) held by the lattice-shaped portion. The positive electrode ear is disposed 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-down direction of the battery case and the stacking direction of the stack), and the negative electrode ear is disposed 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 a plurality of the positive electrode ears and a negative electrode strap connecting a plurality of the negative electrode ears.

[0016] (2) The bag-shaped separator is made of a porous synthetic resin and contains oil. It has a plate-shaped base portion and a plurality of ribs protruding from the plate surface of the base portion, with the ribs being arranged on the inside.

[0017] (3) The positive electrode current collector 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.

[0018] (4) The volume (Ve [cm 2 ) 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 (W [g]) of the positive electrode mixture to the mass (W [g]) of the positive electrode mixture is 0.150 or more. A second aspect of the present invention based on the above findings is a method for producing a flooded lead-acid battery having the above configurations (1) to (3), and has the following configuration (5).

[0019] (5) The volume (Ve [cm 2 ) 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 ribs of the bag-shaped separator are designed so that the ratio (Ve / W) of the mass (Ve [g]) of the positive electrode mixture to the mass (W [g]) of the positive electrode mixture is 0.150 or more. Effect of the Invention

[0020] According to the present invention, it is possible to increase the RC and improve the performance rank of a flooded lead-acid battery without incurring a significant increase in cost or a decrease in lifespan. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a diagram illustrating the flooded lead-acid battery of the embodiment, showing a state in which the lid is removed from the battery case. [Diagram 2] FIG. 2 is a partial cross-sectional view of the flooded lead-acid battery according to the embodiment. [Diagram 3] 3 is a plan cross-sectional view of a laminate constituting the flooded lead-acid battery of the embodiment, and corresponds to the AA cross-sectional view of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention. [Overall battery configuration] As shown in Fig. 1, the flooded lead-acid battery of the embodiment has a monoblock-type battery case 1, a lid (not shown), and six electrode plate groups 2. The shape of the battery case 1 is a rectangular parallelepiped, and the battery case 1 has a pair of first walls 11 formed on a pair of long sides of a rectangle forming a 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.

[0023] One electrode group 2 is disposed in each of the six cell chambers 4, and an electrolyte is poured into each cell chamber 4. The electrolyte is dilute sulfuric acid with a specific gravity of 1.28 to 1.30 (calculated at 20°C). Although not shown, the tops of all of the cell chambers 4 are closed by fixing lids to the battery case 1. As shown in FIG. 1, the direction in which the cell chambers 4 are arranged is the X direction, and the direction perpendicular to this is the Y direction.

[0024] As shown in FIG. 2, the electrode plate group 2 has a laminate 6, and the laminate 6 is composed of a plurality of alternatingly arranged positive electrode plates 10 and negative electrode plates 20, and a separator 30 arranged between the positive electrode plates 10 and the negative electrode plates 20. The number of positive electrode plates 10 constituting the laminate 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, the number of positive electrode plates 10 is one less than the number of negative electrode plates 20.

[0025] 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), and the positive electrode current collector has a rectangular lattice portion and an ear protruding from one side of the rectangle forming the lattice portion, and the positive electrode mixture is held in the lattice portion. In FIG. 2, the lattice portion holding the positive electrode mixture is indicated by reference numeral 101, and the ear of the positive electrode plate 10 is indicated by reference numeral 120. The ear 120 of the positive electrode plate 10 is disposed at a position shifted to one side from the center in the width direction of the lattice portion (the direction perpendicular to the paper surface of FIG. 2). The positive electrode plate 10 will be described in detail later.

[0026] 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), and the negative electrode current collector has a rectangular lattice portion and an ear 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 ear of the negative electrode plate 20 is indicated by reference numeral 220. The ear 220 of the negative electrode plate 20 is disposed at a position shifted from the center of the width direction of the lattice portion (direction perpendicular to the paper surface of FIG. 2) to the other side. The negative electrode plate 20 will be described in detail later.

[0027] 3, the laminate 6 is formed by alternately arranging bag-shaped separators 3 housing positive electrode plates 10 and negative electrode plates 20. The bag-shaped separator 3 is made of porous polyethylene and contains oil at a ratio of 5% by mass to 20% by mass, and has 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.

[0028] For example, the thickness of the base portion 31 is 0.15 mm to 0.25 mm, the protruding height t of the rib 32 is 0.4 mm to 0.6 mm, and the width of the rib 32 is is 1 mm ~4 mm, and the spacing between the ribs 32 is 2 mm to 10 mm. The bag-shaped separator 3 is formed by cutting out a rectangular film of a predetermined length from a strip-shaped porous polyethylene film having a plurality of ribs 32 protruding from the plate surface of a base portion 31, folding the rib 32 side inward in two, and joining the left and right ends by welding. Thus, the bag-shaped separator 3 containing the positive electrode plate 10 and the negative electrode plate 20 are alternately arranged, so that the pair of separators 30 constituting the bag-shaped separator 3 are arranged between the positive electrode plate 10 and the negative electrode plate 20. In other words, the bottom side of the battery case of the two separators 30 and both sides in the width direction of the positive electrode plate to be housed are closed, and the top side of the battery case is open.

[0029] The positive electrode current collector plate is a punched product made of a rolled plate made of a lead alloy, and the lattice portion 101 holding the positive electrode mixture faces multiple 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 in which the positive electrode mixture is held 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 has N positive electrode plates 10 (the number of "bag-shaped separators 3 housing positive electrode plates 10" constituting the laminate 6 is N), an electrolyte retention space with a volume of "Ve / N" exists in one bag-shaped separator 3. Also, W [g] is N times the mass of the positive electrode mixture in one positive electrode plate 10.

[0030] The laminate 6 is housed in the cell chamber 4 with the lamination direction aligned along the X direction and with the plate surfaces of the positive electrode plates 10 and the negative electrode plates 20 aligned along the up-down direction of the cell chamber 4. Each plate group 2 further has a positive electrode strap 71, a negative electrode strap 72, and a positive electrode intermediate pole 71a and a negative electrode intermediate pole 72a rising from the positive electrode strap 71 and the negative electrode strap 72, respectively. The positive electrode strap 71 and the negative electrode strap 72 connect the lugs 120 of the multiple positive electrode plates 10 and the lugs 220 of the multiple negative electrode plates 20 constituting the stack 6 at different positions in the width direction of the positive electrode plates 10 and the negative electrode plates 20 (the direction that becomes the Y direction when inserted into the cell chamber). The plate groups 2 arranged in the cell chambers at both ends in the cell arrangement direction each have a positive electrode pole 8 and a negative electrode pole 9 that serve as external terminals.

[0031] The positive electrode intermediate pole 71a and the negative electrode intermediate pole 72a of the adjacent cell chambers 4 are resistance welded to electrically connect the adjacent cells in series. The positive electrode pole 8 and the negative electrode pole 9 are formed on the positive electrode strap 71 and the negative electrode strap 72 via small pieces 71b and 72b, respectively. The positive electrode pole 8 and the negative electrode pole 9 penetrate the lid and are exposed to the outside.

[0032] [Regarding positive and negative plates] [Method of manufacturing positive and negative electrode plates] The positive electrode mixture and the negative electrode mixture are filled in the openings of each lattice part and are also present in layers on both plate surfaces of the lattice part. The positive electrode mixture and the negative electrode mixture are formed on the lattice part of each current collector plate, for example, as follows.

[0033] First, necessary additives (polypropylene fiber, polyethylene fiber, conductive carbon, etc.) are added to the lead powder, and mixed by dry mixing. Then, water is added and kneaded to obtain a water paste, and sulfuric acid is added to this water paste and kneaded to prepare a positive electrode paste and a negative electrode paste. At this time, an organic shrink-proofing agent such as lignin, which is often used as an additive for negative electrodes, is water-soluble and may be added at the same time as water. Next, the obtained positive electrode paste and negative electrode paste are filled into the openings of each lattice-shaped part, and then preheating, aging, and drying processes are performed to obtain a positive electrode plate and a negative electrode plate before chemical formation. Furthermore, a flooded lead-acid battery is assembled using these, and then chemical formation is performed to form a positive electrode mixture and a negative electrode mixture in each lattice-shaped part.

[0034] [Positive current collector plate] The positive current collector constituting the positive electrode plate 10 is an expanded or punched product made of a rolled plate made of a lead alloy (Pb-Ca alloy). The thickness of the positive current collector is, for example, 0.7 mm or more and 1.1 mm or less.

[0035] [Negative electrode current collector] The negative current collector constituting the negative plate 20 is formed by a continuous casting method using a lead alloy (such as a Pb-Ca-Sn 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 is, for example, 0.8 mm or more and 1.1 mm or less.

[0036] [Action, effect] In the flooded lead-acid battery of the above embodiment, the above-mentioned ratio (Ve / W) in one cell chamber 4 is 0.150 or more, and therefore the RC can be increased and the performance rank of the flooded lead-acid battery can be improved without increasing costs or shortening the lifespan, compared to when the ratio (Ve / W) is less than 0.150.

[0037] If the ratio (Ve / W) is too large, the mass (W) of the positive electrode mixture may be too low to obtain the required RC capacity, so the ratio (Ve / W) is preferably 0.150 to 0.350. The ratio (Ve / W) is more preferably in the range of 0.160 to 0.300, and particularly preferably in the range of 0.190 to 0.260. Furthermore, by containing oil in a ratio of 5% by mass or more and 20% by mass or less in the bag-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 the bag-shaped separator 3 is less than 5% by mass, the high-temperature overcharge durability may be insufficient, whereas if it exceeds 20% by mass, the resistance value becomes so high that the standard value for CCA may not be achieved.

[0038] The oil content in the bag-shaped separator is more preferably in the range of 10% by mass to 15% by mass. 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. EXAMPLES

[0039] [Preparation of test battery] As flooded lead-acid batteries having the same structure as the flooded lead-acid battery of the embodiment, flooded lead-acid batteries having the following configurations were fabricated, except that the cross-sectional shape of the rib 32 was rectangular, not trapezoidal as shown in FIG. The flooded lead-acid batteries of Samples No. 1-1 to No. 1-7 were flooded lead-acid batteries of Q size 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 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 was changed as shown in Table 1.

[0040] The flooded lead-acid batteries of Samples No. 2-1 to No. 2-7 were M-size 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 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 was changed as shown in Table 2. In addition, Ve in Tables 1 and 2 is {(H-rib volume x number of ribs x 2) x number of positive electrodes} cm 3 H is the area of ​​the grid part of the positive electrode plate in s (mm 2 ), 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 later, and W is a value obtained by multiplying the mass of the positive electrode mixture of one positive electrode plate by the number of positive electrodes.

[0041] [No.1-1~No.1-7] <Production of pre-formed positive electrode plates> A positive electrode current collector plate was manufactured by carrying out a slab casting step, a rolling step, and a punching step in this order.

[0042] First, a slab casting process was carried out in the following manner. A block of lead alloy containing 0.06% by mass Ca, 1.6% by mass Sn, 0.02% by mass Al, and the remainder being lead and unavoidable impurities was prepared and melted by heating to obtain a molten metal. The molten metal was poured between two opposing metal rolls and cooled by the metal rolls to obtain a lead alloy slab.

[0043] Next, the obtained lead alloy slab was passed between a pair of upper and lower rolling rolls to carry out a rolling process at a rolling reduction of 90%, thereby obtaining a rolled sheet having a width of 320 mm and a thickness of 1.0 mm. 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 part. The dimensions of the lattice-shaped part are 116.5 mm in the direction in which the ears extend (height), 137.0 mm in the direction perpendicular thereto (width), and 1.0 mm in thickness. Therefore, the area of ​​the lattice-shaped part is 15960.5 mm 2 The ears have a width of 10 mm and a height of 15 mm. The ears extend from between the center and the end of the lattice portion in the width direction.

[0044] A positive electrode paste prepared by a normal method was filled into the grid-like portion of the obtained positive electrode current collector plate, and the plate was aged and dried by a normal method to obtain a positive electrode plate (positive electrode filled plate) before chemical formation.

[0045] <Manufacturing of negative electrode plates before chemical formation> A negative electrode current collector having an upper edge extending upward from the upper frame of a lattice-shaped portion was obtained by continuous casting using a lead alloy containing 0.09 mass% Ca, 0.4 mass% Sn, 0.02 mass% Al, and the remainder being lead and unavoidable impurities. The dimensions of the lattice-shaped portion are 115 mm in the direction in which the edge extends (height), 135 mm in the direction perpendicular thereto (width), and 0.8 mm in thickness. The dimensions of the edge are 10 mm in width and 15 mm in height. The edge extends from between the center and end of the lattice-shaped portion in the width direction.

[0046] The bones of the lattice portion of the obtained negative electrode current collector plate were composed of 16 vertical bones approximately perpendicular to the upper frame bone and 7 horizontal bones approximately perpendicular to the vertical bones. The grid-shaped portion of the obtained negative electrode current collector was filled with 55 g of the negative electrode paste prepared by the following method, and then heat treatment before aging was performed at 400° C. or 300° C. Next, after aging at 40° C. and a relative humidity of 90%, drying was performed at 60° C. to obtain a negative electrode filled plate (negative electrode plate before chemical formation) for each sample.

[0047] The negative electrode paste was prepared by adding water and sulfuric acid to lead powder and kneading the mixture to obtain a water paste, and then adding acetylene black (AB) or ketjen black (KB) as conductive carbon to the water paste in a ratio of 0.2 parts by mass per 100 parts by mass of lead powder and kneading the mixture.

[0048] <Preparation of electrode plates before chemical formation> A pouch-shaped separator was prepared by forming a porous polyethylene separator with vertical ribs and an oil content of 5% by mass into a pouch shape with the vertical rib side facing inward, with 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 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 pouch-shaped separator with an appropriate gap between them.

[0049] A positive electrode packed plate for each sample was placed in a bag-shaped separator. Seven bag-shaped separators containing positive electrode packed plates and eight negative electrode packed plates were stacked alternately to produce six stacks for each sample. Next, using a cast-on-strap (COS) type casting device, straps, intermediate poles, and terminal poles were formed on the positive electrode packing plates and negative electrode packing plates of the six laminates obtained for each sample, thereby obtaining six electrode plate groups for each sample.

[0050] <Battery assembly> Next, the six electrode plates obtained for each sample were placed in six cell compartments of a monoblock type battery container made of polypropylene.

[0051] Next, the intermediate poles between adjacent cell chambers were resistance-welded, and the battery case and lid were heat-welded in the usual manner. Next, an electrolyte consisting of dilute sulfuric acid with a specific gravity of 1.250 (calculated at 20°C) was poured into each cell chamber through each of the injection holes in the lid. Next, the injection holes were sealed to assemble an unformed flooded lead-acid battery. Then, the positive and negative electrode packed plates were converted into positive and negative plates by a normal method of container formation to complete the flooded lead-acid battery. In this state, all of the tip faces of the ribs 32 were in contact with each of the positive electrode packed plates No. 1-1 to No. 1-7 in the pouch-shaped separator.

[0052] [No.2-1~No.2-7] <Production of pre-formed positive electrode plates> The rolled sheet obtained in the same manner as in No.1-1 to No.1-7 was pressed 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 are 105.0 mm in the direction in which the ears 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 is 11,865.0 mm. 2 The ears have a width of 10 mm and a height of 15 mm. The ears extend from between the center and the end of the lattice portion in the width direction.

[0053] A positive electrode paste prepared by a normal method was filled into the grid-like portion of the obtained positive electrode current collector plate, and the plate was aged and dried by a normal method to obtain a positive electrode plate (positive electrode filled plate) before chemical formation.

[0054] <Manufacturing of negative electrode plates before chemical formation> A negative electrode current collector having an upper edge extending upward from the upper frame of a lattice-shaped portion was obtained by continuous casting using a lead alloy containing 0.09% by mass Ca, 0.4% by mass Sn, 0.02% by mass Al, and the remainder being lead and unavoidable impurities. The dimensions of the lattice-shaped portion are 100 mm in the direction in which the edge extends (height), 100 mm in the direction perpendicular thereto (width), and 0.8 mm in thickness. The dimensions of the edge are 10 mm in width and 15 mm in height. The edge extends from between the center and end of the lattice-shaped portion in the width direction.

[0055] The bones of the lattice portion of the obtained negative electrode current collector plate were composed of 16 vertical bones approximately perpendicular to the upper frame bone and 10 horizontal bones approximately perpendicular to the vertical bones. The grid-shaped portion of the obtained negative electrode current collector 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, after aging at 40° C. and a relative humidity of 90%, drying was performed at 60° C. to obtain a negative electrode plate (negative electrode filled plate) before chemical conversion.

[0056] The negative electrode paste was prepared by adding water and sulfuric acid to lead powder and kneading the mixture to obtain a water paste, and then adding acetylene black (AB) or ketjen black (KB) as conductive carbon to the water paste in a ratio of 0.2 parts by mass per 100 parts by mass of lead powder and kneading the mixture.

[0057] <Preparation of electrode plates before chemical formation> A pouch-shaped separator 3 was prepared by forming a porous polyethylene separator with vertical ribs and an oil content of 5% by mass into a pouch shape with the vertical ribs on the inside, with the protruding dimension t of the ribs 32 from the base portion 31, the number of ribs 32, and the width of the ribs 32 as shown in Table 2. The dimensions of the base portion 31 were set so that it could be inserted into the pouch-shaped separator with an appropriate gap.

[0058] A positive electrode packed plate for each sample was placed in a bag-shaped separator. Six bag-shaped separators containing positive electrode packed plates and seven negative electrode packed plates were alternately stacked to produce six stacks for each sample. Next, using a cast-on-strap (COS) type casting device, straps, intermediate poles, and terminal poles were formed on the positive electrode packing plates and negative electrode packing plates of the six laminates obtained for each sample, thereby obtaining six electrode plate groups for each sample.

[0059] <Battery assembly> Except for changing the dimensions of the battery container to match the dimensions of the plate groups No.2-1 to No.2-7, the batteries were assembled in the same manner as No.1-1 to No.1-7, and then the battery container was formed in the usual manner to convert the positive and negative electrode packing plates into positive and negative plates, completing the flooded lead-acid battery. In this state, all the tip surfaces of the ribs 32 are in contact with each of the positive electrode packing plates No.2-1 to No.2-7 inside the bag-shaped separator.

[0060] [Reserve Capacity Test] Using each sample of flooded lead-acid batteries obtained, a discharge test was conducted in a 25°C water tank to 10.5V at 25A in accordance with 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 is minutes) was calculated. The calculated RCe (min) was 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 utilization rate of the reserve capacity (hereinafter referred to as "RC utilization rate" or simply "utilization rate"). These results are shown in Tables 1 and 2 together with the separator configuration and ratio (Ve / W).

[0061] [Table 1]

[0062] [Table 2]

[0063] As can be seen from the results in Table 1, in the case of Q size, flooded lead-acid batteries No. 1-3 to No. 1-7 with a ratio (Ve / W) of 0.150 or more have an RC utilization rate of 37% or more, whereas flooded lead-acid batteries No. 1-1 and No. 1-2 with a ratio (Ve / W) of less than 0.150 have an RC utilization rate of about 35%. Also, if the difference in utilization rate with the standard No. 1-2 is 2.0 or more, it is considered that the necessary regulations are met, but flooded lead-acid batteries No. 1-3 to No. 1-7 with a ratio (Ve / W) of 0.150 or more have a difference in utilization rate with No. 1-2 of 2.3% or more.

[0064] Also, as can be seen from the results in Table 2, in the case of M size, flooded lead-acid batteries No. 2-3 to No. 2-7 with a ratio (Ve / W) of 0.150 or more have an RC utilization rate of 29.5% or more, whereas flooded lead-acid batteries No. 2-1 and No. 2-2 with a ratio (Ve / W) of less than 0.150 have an RC utilization rate of less than 27%. Also, if the difference in utilization rate with the standard No. 2-2 is 2.0 or more, it is considered that the necessary regulations are met, but flooded lead-acid batteries No. 2-3 to No. 2-7 with a ratio (Ve / W) of 0.150 or more have a difference in utilization rate with No. 2-2 of 2.9% or more.

[0065] 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 from the reference product. Secondly, by making the ratio (Ve / W) 0.150 or more, it is possible to satisfy the necessary regulations.

[0066] [Evaluation based on oil content] <Battery assembly> Except for using pouch-shaped separators 3 with oil contents of 3 mass%, 10 mass%, 15 mass%, 20 mass%, and 25 mass%, flooded lead-acid batteries No. 1-11 to No. 1-15 were produced by assembling batteries in the same manner as No. 1-3.

[0067] Except for using pouch-shaped separators 3 with oil contents of 3 mass%, 10 mass%, 15 mass%, 20 mass%, and 25 mass%, flooded lead-acid batteries No. 2-11 to No. 2-15 were produced by assembling batteries in the same manner as No. 2-4.

[0068] <Test Method> First, in accordance with "JIS D 5301," discharge tests were performed at 590 A for No. 1-3, No. 1-11 to No. 1-15 flooded lead-acid batteries and at 310 A for No. 2-4, No. 2-11 to No. 2-15 flooded lead-acid batteries at a battery temperature of -18°C, and the voltage at 30 seconds was measured.

[0069] Next, in order to evaluate the high-temperature overcharge durability, a light-load life test was performed as described in "JIS D5301." In order to increase 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 discharging for 60 seconds at a discharge current of 25A in a 75°C environment, followed by charging for 10 minutes at a charging voltage of 14.8V.

[0070] After repeating this cycle for every 480 cycles, a 30-second life-determining discharge was performed at 590 A for No. 1-3, No. 1-11 to No. 1-15, and at 310 A for No. 2-4, No. 2-11 to No. 2-15. The number of cycles at which the 30-second voltage dropped to 7.2 V, or the number of cycles at which the current value showed an upward trend during the 10-minute charge, suggesting a short circuit, was determined as the high-temperature overcharge life.

[0071] 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 No. 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 No. 2-4 set to 100.

[0072] [Table 3]

[0073] [Table 4]

[0074] As can be seen from the results in Table 3, in the flooded lead-acid batteries No. 1-3 and No. 1-11 to No. 1-14, in which the oil content of the bag-shaped separator was between 3% by mass and 20% by mass, the 30-second voltage was equal to or higher than 7.2 V, which is the CCA standard value. However, in the flooded lead-acid battery No. 1-15, in which the oil content was 25% by mass, the 30-second voltage was 6.8 V, which is below the standard value. In addition, in the flooded lead-acid batteries No. 1-3 and No. 1-12 to No. 1-15, in which the oil content of the bag-shaped separator was 5% by mass or more and 25% by mass or less, the relative value of the high-temperature overcharge life was 100 or more, while the flooded lead-acid battery No. 1-11, in which the oil content of the bag-shaped separator was 3% by mass, had a relative value of 95 (less than 100).

[0075] Furthermore, as can be seen from the results in Table 4, in the flooded lead-acid batteries No. 2-4 and No. 2-11 to No. 2-14, in which the oil content of the bag-shaped separator was between 3% by mass and 20% by mass, the 30-second voltage was equal to or higher than 7.2 V, which is the CCA standard value. However, in the flooded lead-acid battery No. 2-15, in which the oil content was 25% by mass, the 30-second voltage was 7.1 V, which is less than the standard value. In addition, in the flooded lead-acid batteries No. 2-4 and No. 2-12 to No. 2-15, in which the oil content of the bag-shaped separator was 5% by mass or more and 25% by mass or less, the relative value of the high-temperature overcharge life was 100 or more, while the flooded lead-acid battery No. 2-11, in which the oil content of the bag-shaped separator was 3% by mass, had a relative value of 93 (less than 100).

[0076] As can be seen from the above, in a flooded lead-acid battery with a high RC, that is, with a ratio (Ve / W) of 0.150 or more, by setting the oil content of the bag-shaped separator to be 5% by mass or more and 20% by mass or less, both CCA and high-temperature overcharge life can be improved. [Explanation of symbols]

[0077] 1 battery case 11 The first wall of the battery case 12 The second wall of the battery case 13 Battery case bulkhead 2 Plate group 3. Bag-shaped separator 30 Separator 4 Cell Room 6 Laminate 10 Positive electrode plate 101 The grid-like portion of the positive electrode current collector plate in which the positive electrode mixture is held 120 Positive electrode collector plate lug 20 Negative plate 201 The grid-shaped portion of the negative electrode current collector plate holding the negative electrode mixture 220 Negative electrode current collector lug 71 Positive strap 72 Negative strap 71a Positive electrode intermediate pole 72a Negative intermediate pole 8 Positive terminal 9 Negative terminal

Claims

1. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte injected into the cell chamber; the electrode plate group has a laminate formed by disposing separators between a plurality of alternatingly arranged positive electrode plates and negative electrode plates, and by alternately disposing the negative electrode plates and bag-shaped separators housing the positive electrode plates, The positive electrode plate includes a positive electrode current collector including a lattice portion, a positive electrode lug protruding upward from the lattice portion in the up-down direction of the battery case, and a positive electrode mixture held by the lattice portion, The negative electrode plate includes a negative electrode current collector including a lattice portion, a negative electrode lug protruding upward from the lattice portion in the up-down direction of the battery case, and a negative electrode mixture held by the lattice portion, the positive electrode ear portion is disposed at a position shifted to one side from the center of the width direction of the lattice portion, and the negative electrode ear portion is disposed at a position shifted to the other side from the center of the width direction of the lattice portion, The electrode plate group further includes a positive electrode strap connecting a plurality of the positive electrode ears and a negative electrode strap connecting a plurality of the negative electrode ears, The bag-shaped separator is made of a porous synthetic resin and contains oil, and has a plate-shaped base portion and a plurality of ribs protruding from a 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, and the lattice-shaped portion holding the positive electrode mixture faces the plurality of ribs, The volume (Ve [cm 2 ] 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 ]) to the mass (W [g]) of the positive electrode mixture, V / W being 0.150 or more and 0.350 or less.

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

3. 3. The flooded lead-acid battery according to claim 1, wherein the oil content of the pouch-shaped separator is 5% by mass or more and 20% by mass or less.

4. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte injected into the cell chamber; the electrode plate group has a laminate formed by disposing separators between a plurality of alternatingly arranged positive electrode plates and negative electrode plates, and by alternately disposing the negative electrode plates and bag-shaped separators housing the positive electrode plates, The positive electrode plate includes a positive electrode current collector including a lattice portion, a positive electrode lug protruding upward from the lattice portion in the up-down direction of the battery case, and a positive electrode mixture held by the lattice portion, The negative electrode plate includes a negative electrode current collector including a lattice portion, a negative electrode lug protruding upward from the lattice portion in the up-down direction of the battery case, and a negative electrode mixture held by the lattice portion, the positive electrode ear portion is disposed at a position shifted to one side from the center of the width direction of the lattice portion, and the negative electrode ear portion is disposed at a position shifted to the other side from the center of the width direction of the lattice portion, The electrode plate group further includes a positive electrode strap connecting a plurality of the positive electrode ears and a negative electrode strap connecting a plurality of the negative electrode ears, The bag-shaped separator is made of a porous synthetic resin and contains oil, and has a plate-shaped base portion and a plurality of ribs protruding from a 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, and the grid-shaped portion holding the positive electrode mixture faces the plurality of ribs. The volume (Ve [cm 2 ] 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 ribs of the bag-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 (W [g]) is 0.150 or more and 0.350 or less.

5. 5. The method for producing 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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