Liquid lead-acid battery

Abstract

To provide a novel technique capable of improving a utilization rate of a cathode positive material in a liquid type lead storage battery comprising a cathode plate in which a cathode mixture is held in a lattice-shaped part of a cathode collector plate.SOLUTION: An electrode plate group 1 of a liquid type lead storage battery includes a laminate comprising: a plurality of cathode plates 10 and anode plates 20 disposed alternately; and separators disposed between the cathode plates 10 and the anode plates 20. The anode plate 10 comprises a cathode collector plate including a lattice-shaped part and a cathode mixture held in the lattice-shaped part and is obtained by filling the lattice-shaped part with cathode mixture plate and executing maturation and dry steps. The cathode mixture paste contains a lead powder and metal tin in a flat shape. An average thickness of the metal tin is 0.10 μm or more and 1.0 μm or less, an average aspect ratio of a surface of the metal tin in parallel to a vertical direction is 1.1 or more and 1.7 or less, and a ratio of the metal tin with respect to 100 pts.mass of the lead powder is 0.10 pt.mass or more and less than 1.0 pt.mass.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A typical 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 is a stack of alternatingly arranged positive and negative plates and a separator disposed between the positive and negative plates. The positive plate includes a positive 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. The negative plate includes a negative 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. Dilute sulfuric acid is used as the electrolyte. Such flooded lead-acid batteries are widely used as automobile batteries, etc.

[0003] With the recent trend toward more sophisticated automotive electrical systems, the lead-acid batteries used as power sources are also required to have a larger discharge capacity. The discharge capacity of lead-acid batteries can be improved, for example, by improving the utilization rate of the positive electrode active material. A known technique for improving the utilization rate of the positive electrode active material in a lead-acid battery is to incorporate a tin-based additive into the positive electrode mixture containing the positive electrode active material. For example, Patent Document 1 describes that adding flaky conductive ceramics containing tin oxide as the main component to the positive electrode mixture paste of a lead-acid battery (1 to 8 mass % of the active material) can improve the charge / discharge cycle life and energy density.

[0004] Patent Document 2 describes the inclusion of a carbon-based additive and a tin-based additive in a positive electrode active material to improve utilization, extend the life of the positive electrode plate, and improve battery performance. Examples of tin-based additives include metallic tin, tin oxide, tin sulfide, and tin hydroxide. It also describes that the shape of the metallic tin or tin compound is not limited to powder, scale, or flake, but is preferably a shape with a large average aspect ratio, such as a plate, whisker, or fiber, because it provides a high conductivity even when added in small amounts. In the examples, tin oxide fiber powder is used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-187820 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-43861 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a new technology that can improve the utilization rate of the positive electrode active material in a flooded lead-acid battery having a positive electrode plate in which a positive electrode mixture is held in the grid-like portion of the positive electrode current collector plate. [Means for solving the problem]

[0007] In order to solve the above problems, a first aspect of the present invention provides a flooded lead-acid battery having the following features (a) to (c). (a) A battery container having a cell chamber, a plate assembly housed in the cell chamber, and an electrolyte solution poured into the cell chamber. The plate assembly has a stack including a plurality of alternately arranged positive and negative electrode plates and a separator disposed between the positive and negative electrode plates. (b) The positive electrode plate has a positive electrode current collector plate with a grid-shaped portion and a positive electrode mixture held in the grid-shaped portion, and is obtained by filling the grid-shaped portion with a positive electrode mixture paste and then undergoing an aging and drying process. (c) The positive electrode mixture paste contains lead powder and flat metallic tin, the metallic tin having an average thickness of 0.10 μm or more and 1.0 μm or less, an average aspect ratio of a surface perpendicular to the thickness direction of the metallic tin being 1.1 or more and 1.7 or less, and a ratio of the metallic tin to 100 parts by mass of the lead powder being 0.10 parts by mass or more and less than 1.0 part by mass.

[0008] A second aspect of the present invention provides a flooded lead-acid battery having the above configurations (a) and (b) and the following configuration (d). (d) The positive electrode mixture paste contains lead powder and flat metallic tin, the metallic tin having an average thickness of 0.10 μm or more and 1.0 μm or less, an average aspect ratio of a surface perpendicular to the thickness direction of the metallic tin being 1.1 or more and 1.7 or less, and a ratio of the metallic tin to 100 parts by mass of the lead powder being 0.20 parts by mass or more and 0.50 parts by mass or less.

[0009] A third aspect of the present invention provides a flooded lead-acid battery having the above features (a) and (b) and the following feature (e): (e) The positive electrode mixture paste contains lead powder and flat metallic tin, the metallic tin having an average thickness of 0.15 μm or more and 0.50 μm or less, an average aspect ratio of a surface perpendicular to the thickness direction of the metallic tin being 1.1 or more and 1.7 or less, and a ratio of the metallic tin to 100 parts by mass of the lead powder being 0.20 parts by mass or more and 0.50 parts by mass or less.

[0010] A fourth aspect of the present invention provides a method for manufacturing a flooded lead-acid battery having the following configurations (f) to (h). (f) A method for manufacturing a flooded lead-acid battery comprising: a battery case having a cell chamber; a plate group housed in the cell chamber; and an electrolyte injected into the cell chamber, wherein the plate group has a stack including a plurality of alternately arranged positive and negative plate sheets and a separator disposed between the positive and negative plate sheets; and wherein the positive plate includes a positive current collector plate having a grid portion and a positive electrode mixture held in the grid portion. (g) A step of filling the grid-shaped portion with a positive electrode mixture paste, a step of performing aging and drying after the step to obtain a positive electrode mixture filled plate, and a step of chemically converting the positive electrode mixture filled plate to obtain the positive electrode plate. (h) The positive electrode mixture paste contains lead powder and flat metallic tin, the metallic tin has an average thickness of 0.10 μm or more and 1.0 μm or less, the metallic tin has an average aspect ratio of a surface perpendicular to the thickness direction of 1.1 or more and 1.7 or less, and the ratio of the metallic tin to 100 parts by mass of the lead powder is 0.10 parts by mass or more and less than 1.0 part by mass. [Effects of the Invention]

[0011] According to the present invention, in a flooded lead-acid battery having a positive electrode plate in which a positive electrode mixture is held in the grid-like portion of the positive electrode current collector, an improvement in the utilization rate of the positive electrode active material can be expected. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a partial cross-sectional view showing the structure of a flooded lead-acid battery according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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. [Overall configuration] 1, the flooded lead-acid battery of this embodiment includes a battery case 41 having a cell chamber, a plate assembly 1 housed in the cell chamber, a positive electrode terminal 14, a negative electrode terminal 24, an electrolyte (not shown) poured into the cell chamber, and a lid 43 fixed to the battery case 41 to close the top of the cell chamber. The plate assembly 1 includes a stack made up of multiple alternatingly 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, a positive electrode strap 13 connecting the positive electrode plates 10 of the stack, and a negative electrode strap 23 connecting the negative electrode plates 20 of the stack.

[0014] The stack of electrode plate packs 1 is placed in the battery case 41 with the plate surfaces of the grid-like portions of the positive electrode plates 10 and negative electrode plates 20 aligned in the vertical direction of the battery case 41. One electrode plate pack 1 is housed in one cell chamber. The number of positive electrode plates 10 constituting the stack of electrode plate pack 1 may be the same as or greater than the number of negative electrode plates 20, but in this embodiment, the number is one less than the number of negative electrode plates 20.

[0015] The positive electrode plate 10 has a positive electrode current collector plate with a rectangular grid portion and continuous tab portions 12, and a positive electrode mixture (a mixture containing a positive electrode active material) held in the grid portion. The positive electrode plate 10 is obtained by filling the grid portion with a specific positive electrode mixture paste and then undergoing a normal aging and drying process. The positive electrode mixture is filled in the openings of the grid portion of the positive electrode current collector plate and is present on both plate surfaces of the grid portion. Details of the specific positive electrode mixture paste will be described later.

[0016] The negative electrode plate 20 has a negative electrode current collector plate with a rectangular grid portion and continuous tab portions 22, and a negative electrode mixture (a mixture containing a negative electrode active material) held in the grid portion, and is obtained by filling the grid portion with a normal negative electrode mixture paste, followed by an aging and drying process. The negative electrode mixture is filled in the openings of the grid portion of the negative electrode current collector plate, and is also present on both plate surfaces of the grid portion.

[0017] The positive electrode current collector constituting the positive electrode plate 10 is formed by gravity casting using a Pb-Sn alloy. The negative electrode current collector constituting the negative electrode plate 20 is formed by continuous casting using a Pb-Ca alloy. Other manufacturing methods for the positive electrode current collector and the negative electrode current collector include a punching method using a rolled lead alloy plate and an expanding method using a rolled lead alloy plate. The separator 30 is a porous film made of, for example, resin, glass fiber, or the like, and may have pleated ribs protruding perpendicular to the base surface formed on a flat base (film).

[0018] The lugs 12 of the multiple positive plates 10 are connected by positive electrode straps 13, and the lugs 22 of the multiple negative plates 20 are connected by negative electrode straps 23. One end of a positive electrode terminal 14 is connected to the top of the positive electrode strap 13, and one end of a negative electrode terminal 24 is connected to the top of the negative electrode strap 23. The other ends of the positive electrode terminal 14 and the negative electrode terminal 24 penetrate a lid 43 that closes the opening of a battery case 41, and are exposed to the outside of the case body of the flooded lead-acid battery, which is made up of the battery case 41 and the lid 43. The flooded lead-acid battery of this embodiment is obtained by storing the electrode plate group 1 in the battery case 41, fixing the lid 43, and then injecting an electrolyte into the battery case 41 through a pouring port provided in the lid 43 to perform battery case formation. The electrolyte is dilute sulfuric acid with a specific gravity of 1.28 to 1.30 (calculated at 20°C).

[0019] [Regarding specific positive electrode mixture paste] The positive electrode mixture paste filled in the grid portion of the positive electrode current collector plate contains lead powder and flat metallic tin, the average thickness of the metallic tin is 0.10 μm or more and 1.0 μm or less, the average aspect ratio of the plane perpendicular to the thickness direction of the metallic tin is 1.1 or more and 1.7 or less, and the ratio of the metallic tin to 100 parts by mass of lead powder is 0.10 parts by mass or more and less than 1.0 part by mass. The method for producing this positive electrode mixture paste is the same as a normal method, except that the metallic tin having the above composition is added in the above-mentioned formulation.

[0020] This positive electrode mixture paste is filled into the grid portion of a positive electrode current collector plate, and then a normal aging and drying process is performed to obtain a positive electrode filled plate (a positive electrode plate before chemical formation). The resulting positive electrode filled plate, a negative electrode filled plate (a negative electrode plate before chemical formation) similarly obtained using a normal negative electrode mixture, and a separator are used to form a stack, and the resulting electrode plate group is then placed in a battery case and subjected to battery case chemical formation, whereby the positive electrode filled plate becomes a positive electrode plate and the negative electrode filled plate becomes a negative electrode plate.

[0021] The "average aspect ratio of flat tin metal" is defined as the ratio of the average major axis diameter to the average minor axis diameter in a plane perpendicular to the thickness direction of the flat tin metal (average major axis diameter / average minor axis diameter). The average thickness and the average major axis diameter and average minor axis diameter of the flat tin metal can be calculated, for example, by the following method. Using a scanning electron microscope, at least 20 or more pieces of flat tin metal are sampled, and the thickness and the major axis diameter and minor axis diameter in a plane perpendicular to the thickness direction (considered to be an ellipsoid) of at least five of these pieces are measured, and the average major axis diameter, average minor axis diameter, and average thickness are calculated.

[0022] Furthermore, the flat metallic tin contained in the positive electrode mixture paste may exist in the positive electrode mixture held in the grid portion of the positive electrode plate after chemical formation not only as metallic tin but also as a tin compound (for example, a tin compound such as an oxide, sulfide, or hydroxide, where the valence of tin may be either divalent or tetravalent). Also, some of the metallic tin may dissolve from the positive electrode mixture into the electrolyte and exist as tin ions (divalent and / or tetravalent), and some of the tin ions dissolved in the electrolyte may precipitate on the negative electrode plate in the form of metallic tin or a tin compound.

[0023] The average aspect ratio and average thickness of the flat metallic tin contained in the positive electrode mixture paste can be adjusted by the metallic tin pulverization method and processing conditions. For example, when pulverizing a tin source in a ball mill, the rotation speed of the ball mill, or the amount, size, or weight of the milling medium can be changed to obtain flat metallic tin with an adjusted average aspect ratio and average thickness. The area of ​​the surface perpendicular to the thickness direction of the flat metal tin is not particularly limited, but is, for example, 100 μm 2 More than 1000μm 2 It is preferable that:

[0024] [Action, effect] In the flooded lead-acid battery of this embodiment, a positive electrode mixture paste "contains lead powder and flat metallic tin, the average thickness of the metallic tin is 0.10 μm or more and 1.0 μm or less, and the average aspect ratio of the planes perpendicular to the thickness direction of the metallic tin is 1.1 or more and 1.7 or less," and "the ratio of the metallic tin to 100 parts by mass of lead powder is 0.10 parts by mass or more and less than 1.0 part by mass." By using this, the utilization rate of the positive electrode active material during discharge is higher compared to a positive electrode mixture paste in which the shape, etc. of the metallic tin (flat shape, average aspect ratio, and average thickness) and the ratio of the metallic tin to the lead powder are outside the above ranges. [Example]

[0025] [Preparation of test battery] Samples No. 1 to No. 25 of flooded lead-acid batteries were fabricated as flooded lead-acid batteries having the same structure as the flooded lead-acid battery of the embodiment. Specifically, a JIS B20-sized battery case with a single cell compartment was prepared, and a single electrode plate group was placed in the cell compartment to fabricate a flooded lead-acid battery (operating voltage: 2 V, rated capacity: 32 Ah) with a single cell compartment. Samples No. 1 to No. 25 of the flooded lead-acid batteries all had the same configuration, except for the positive electrode mixture paste used.

[0026] First, a positive current collector plate made of a Pb-Ca-Sn lead alloy conforming to JIS B20 size was produced by gravity casting. Next, a negative current collector plate made of a Pb-Ca-Sn lead alloy conforming to JIS B20 size was produced by continuous casting. The positive and negative current collector plates consisted of a roughly rectangular lattice portion and lugs. The lattice portion had a frame that formed the four sides of the rectangle, and vertical and horizontal inner ribs arranged within the frame. The frame, vertical inner ribs, and horizontal inner ribs formed multiple openings.

[0027] [Preparation of positive electrode plate before chemical formation] Next, the grid-shaped portion of the positive electrode current collector plate was filled with a positive electrode mixture paste prepared by the following method for each sample, and then aging and drying processes were performed to obtain a positive electrode mixture-filled plate (positive electrode plate before chemical conversion). The aging and drying processes were performed by aging for 48 hours in a space at a temperature of 40°C and a humidity of 95% or more, and then drying at a temperature of 60°C for 24 hours or more.

[0028] <Positive electrode mixture paste for each sample> The positive electrode mixture paste used in No. 1 was prepared in the following manner. First, 2000 g of lead powder, primarily composed of lead monoxide, was mixed with 400 g of water and 175 g of sulfuric acid with a specific gravity of 1.37. Next, the necessary additives (polyester fiber, bismuth oxide) were added to the resulting water mixture and mixed together, similar to conventional methods, to obtain a positive electrode mixture paste.

[0029] The positive electrode mixture paste used in No. 2 was obtained by adding 10 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.50 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0030] The positive electrode mixture paste used in No. 3 was obtained by adding 10 g of spherical metallic tin with an average particle size of 45 μm to the same water-based paste as No. 1, as well as the same necessary additives as in the conventional case, and kneading them together. In other words, this positive electrode mixture paste contains 0.50 parts by mass of spherical metallic tin for every 100 parts by mass of lead powder.

[0031] The positive electrode mixture paste used in No. 4 was obtained by adding 10 g of fibrous metallic tin with an average length of 51.0 μm and an average diameter of 1.0 μm to the same water-based paste as No. 1, as well as the same necessary additives as in the conventional case, and kneading them together. In other words, this positive electrode mixture paste contains 0.50 parts by mass of fibrous metallic tin per 100 parts by mass of lead powder.

[0032] The positive electrode mixture paste used in No. 5 was obtained by adding 10 g of metallic tin having an average major axis diameter of 26.0 μm and an average minor axis diameter of 19.0 μm (average aspect ratio of 1.4) on the surface perpendicular to the thickness direction, an average thickness of 6 μm, and numerous depressions on the entire surface (both bases and peripheral surfaces of the elliptical cylinder) to the same aqueous mixture as No. 1, in addition to the necessary additives as in the conventional case, and kneading them together. In other words, this positive electrode mixture paste contained 0.50 parts by mass of metallic tin with a thickness of more than 1.0 μm and low flatness per 100 parts by mass of lead powder.

[0033] The positive electrode mixture paste used in No. 6 was obtained by adding not only the same necessary additives as in No. 1 to the same water kneaded product, but also 1 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction, and an average thickness of 0.75 μm, and kneading them together. In other words, this positive electrode mixture paste contains 0.05 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0034] The positive electrode mixture paste used in No. 7 was obtained by adding 2 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.10 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0035] The positive electrode mixture paste used in No. 8 was obtained by adding 4 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.20 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0036] The positive electrode mixture paste used in No. 9 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0037] The positive electrode mixture paste used in No. 10 was obtained by adding not only the same necessary additives as in No. 1 to the same water-based paste as No. 1, but also 8 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction, and kneading them together. In other words, this positive electrode mixture paste contains 0.40 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0038] The positive electrode mixture paste used in No. 11 was obtained by adding 12 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.60 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0039] The positive electrode mixture paste used in No. 12 was obtained by adding 15 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.75 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0040] The positive electrode mixture paste used in No. 13 was obtained by adding 18 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, as well as the same necessary additives as in No. 1 to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.90 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0041] The positive electrode mixture paste used in No. 14 was obtained by adding 20 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.75 μm, as well as the same necessary additives as in No. 1 to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 1.00 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0042] The positive electrode mixture paste used in No. 15 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.05 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0043] The positive electrode mixture paste used in No. 16 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.10 μm, as well as the same necessary additives as in No. 1 to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0044] The positive electrode mixture paste used in No. 17 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.15 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0045] The positive electrode mixture paste used in No. 18 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.30 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0046] The positive electrode mixture paste used in No. 19 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 0.50 μm, as well as the same necessary additives as in No. 1 to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0047] The positive electrode mixture paste used in No. 20 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 1.00 μm, as well as the same necessary additives as in No. 1 to the same water kneaded product as in No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0048] The positive electrode mixture paste used in No. 21 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 36.2 μm and an average minor axis diameter of 27.0 μm (average aspect ratio of 1.3) in the plane perpendicular to the thickness direction and an average thickness of 1.50 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0049] The positive electrode mixture paste used in No. 22 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 35.2 μm and an average minor axis diameter of 34.8 μm (average aspect ratio of 1.0) in the plane perpendicular to the thickness direction and an average thickness of 0.30 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0050] The positive electrode mixture paste used in No. 23 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 35.7 μm and an average minor axis diameter of 33.3 μm (average aspect ratio of 1.1) in the plane perpendicular to the thickness direction and an average thickness of 0.30 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0051] The positive electrode mixture paste used in No. 24 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 39.6 μm and an average minor axis diameter of 22.8 μm (average aspect ratio of 1.7) in the plane perpendicular to the thickness direction and an average thickness of 0.30 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0052] The positive electrode mixture paste used in No. 25 was obtained by adding 5 g of flat metallic tin having an average major axis diameter of 39.8 μm and an average minor axis diameter of 21.6 μm (average aspect ratio of 1.8) in the plane perpendicular to the thickness direction and an average thickness of 0.30 μm, in addition to the conventional necessary additives, to the same water kneaded product as No. 1. In other words, this positive electrode mixture paste contains 0.25 parts by mass of flat metallic tin per 100 parts by mass of lead powder.

[0053] The flat metal tin used in preparing the positive electrode mixture pastes No. 2 and No. 6 to No. 25 had slight dents on the edges (the peripheral surface of the elliptical cylinder), but almost no dents on either side in the thickness direction. Also, the flat metal tin used in preparing the positive electrode mixture pastes No. 2 and No. 6 to No. 25 had a surface area perpendicular to the thickness direction of 100 μm 2 More than 1000μm 2 It was within the following range:

[0054] 〔others〕 The grid-shaped portion of the negative electrode current collector was filled with lead paste prepared by a conventional method using the following composition. The composition for the negative electrode active material paste was a mixture of lead powder, cut polyester fiber, carbon black, lignin, and barium sulfate. After filling, the negative electrode was subjected to conventional processing to obtain a pre-chemically formed negative electrode plate.

[0055] Next, the unformed negative electrode plates were placed in a polyethylene separator bag, and seven separators containing unformed negative electrode plates and six unformed positive electrode plates were alternately stacked to obtain two stacks for each sample. Next, the lugs of the unformed positive electrode plates and the lugs of the unformed negative electrode plates of the stacks were welded together with a gas burner, respectively, to obtain one electrode plate assembly for each sample. Next, the cell chamber of the prepared battery (space volume: 706.86 cm 3 After placing one electrode assembly in the cell, a cover, lead wires, and extension terminals were attached, and an electrolyte consisting of dilute sulfuric acid with a specific gravity of 1.23 was poured into the cell chamber. Next, the battery was formed with a charging amount of electricity of 230% of the theoretical capacity of the positive electrode, to obtain flooded lead-acid batteries No. 1 to No. 25.

[0056] [Evaluation test] Using each of the resulting flooded lead-acid batteries, a test was carried out to examine the positive electrode utilization rate by the following method. In accordance with JIS D 5301, each flooded lead-acid battery was placed in a water tank at 25°C and discharged at a constant current of 5 hours at a rate until the cut-off voltage reached 10.5 V. The positive electrode utilization of each flooded lead-acid battery was calculated by dividing the discharge capacity at 10.5 V by the theoretical capacity, and the positive electrode utilization of the No. 1 flooded lead-acid battery was set to 100 as a relative value.

[0057] <Comparison of examples with and without metallic tin and different shapes> First, the test results for No. 1 to No. 5 flooded lead-acid batteries are shown in Table 1, along with the positive electrode plate configuration of each flooded lead-acid battery (ratio of metallic tin to lead powder contained in the positive electrode mixture paste, average major axis diameter, average minor axis diameter, average aspect ratio, and average thickness). That is, Table 1 summarizes the results of a flooded lead-acid battery (No. 1) using a positive electrode mixture paste that does not contain metallic tin, a flooded lead-acid battery (No. 2) using a positive electrode mixture paste that contains "flat metallic tin having an average aspect ratio of 1.3 on the surfaces perpendicular to the thickness direction and an average thickness of 0.75 μm" at a ratio of 0.50 parts by mass per 100 parts by mass of lead powder, and flooded lead-acid batteries (No. 3 to No. 5) using a positive electrode mixture paste that contains metallic tin at a ratio of 0.50 parts by mass per 100 parts by mass of lead powder but that is not "flat metallic tin having an average aspect ratio of 1.1 or more and 1.7 or less on the surfaces perpendicular to the thickness direction and an average thickness of 0.10 μm or more and 1.0 μm or less."

[0058] [Table 1]

[0059] The results in Table 1 reveal the following: The No. 2 flooded lead-acid battery, which used a positive electrode mixture paste containing 0.50 parts by mass of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" per 100 parts by mass of lead powder, had a higher positive electrode utilization rate than the No. 1 flooded lead-acid battery, which used a positive electrode mixture paste that did not contain metallic tin.However, even if the positive electrode mixture paste contained metallic tin in the same proportion, if the metallic tin was not "flat metallic tin with an average aspect ratio of 1.1 to 1.7 on the surface perpendicular to the thickness direction and an average thickness of 0.10 μm to 1.0 μm" (flooded lead-acid batteries No. 3 to No. 5), no improvement in positive electrode utilization rate was obtained.The following reasons are thought to be the cause of this result.

[0060] In the No. 2 flooded lead-acid battery, a positive electrode mixture paste containing "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" was used, which resulted in the presence of flat metallic tin with a large specific surface area in the pre-chemical positive electrode mixture present in the positive electrode mixture filled plate (pre-chemical positive electrode plate). This metallic tin with a large specific surface area provided high electronic conductivity to the positive electrode active material in the positive electrode mixture of the post-chemical positive electrode plate, which is thought to be the reason for the improved positive electrode utilization rate in the No. 2 flooded lead-acid battery.

[0061] In contrast, in the No. 3 flooded lead-acid battery, the spherical metallic tin has a smaller contact area with the positive electrode active material particles than flat metallic tin, so it is thought that the effect of imparting electronic conductivity to the positive electrode active material was not obtained, and the effect of improving the positive electrode utilization rate was not obtained. Furthermore, in the No. 4 flooded lead-acid battery, although fibrous metallic tin has a higher specific surface area than flat metallic tin, it is easily eluted from the positive electrode mixture into the electrolyte during the formation of the battery container. As a result, the fibrous metallic tin is not present in the positive electrode mixture, and the effect of imparting electronic conductivity to the positive electrode active material is not obtained, and it is thought that the effect of improving the positive electrode utilization rate was not obtained.

[0062] Furthermore, in No. 5 flooded lead-acid battery, the average aspect ratio of the surface perpendicular to the thickness direction was 1.4, but the average thickness was 6 μm and the positive electrode mixture paste used contained metallic tin with low flatness. This reduced the contact area between the positive electrode active material particles and the metallic tin particles, and it is thought that this did not provide the effect of imparting electronic conductivity to the positive electrode active material in the positive electrode mixture of the positive electrode plate after chemical formation, and therefore did not improve the positive electrode utilization rate.

[0063] <Comparison of different ratios of flat metal tin to lead powder> Next, the test results for No. 2 and No. 6 to No. 14 flooded lead-acid batteries are shown in Table 2, along with the positive electrode plate configuration of each flooded lead-acid battery (ratio of metallic tin to lead powder contained in the positive electrode mixture paste, average major axis diameter, average minor axis diameter, average aspect ratio, and average thickness). In other words, Table 2 summarizes the results of flooded lead-acid batteries using positive electrode mixture pastes containing "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" in different proportions (ranging from 0.05 parts by mass to 1.00 parts by mass) per 100 parts by mass of lead powder.

[0064] [Table 2]

[0065] The results in Table 2 reveal the following: The No. 2 and No. 7 to No. 13 flooded lead-acid batteries, which used positive electrode mixture paste containing 0.10 to 0.90 parts by mass of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" per 100 parts by mass of lead powder, had improved positive electrode utilization rates (relative values ​​of 101 or more) compared to the No. 1 flooded lead-acid battery, which used positive electrode mixture paste that did not contain metallic tin. However, the No. 6 and No. 14 flooded lead-acid batteries, which used positive electrode mixture paste containing 0.05 and 1.00 parts by mass of metallic tin per 100 parts by mass of lead powder, had positive electrode utilization rates that were equal to or lower than that of the No. 1 flooded lead-acid battery, which used positive electrode mixture paste that did not contain metallic tin.

[0066] The reason for these results is thought to be that the ratio of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" to the lead powder was too low in No. 6 flooded lead-acid battery to obtain the effect of the flat metallic tin, and was too high in No. 14 flooded lead-acid battery. If the ratio of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" to the lead powder is too high, the flat metallic tin will inhibit contact between the positive electrode active material and the electrolyte, which is thought to reduce the positive electrode utilization rate.

[0067] Furthermore, among No. 2 and No. 7 to No. 13 flooded lead-acid batteries, No. 2 and No. 8 to No. 10 flooded lead-acid batteries using a positive electrode mixture paste containing 0.20 to 0.50 parts by mass of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.75 μm" per 100 parts by mass of lead powder had a significant effect in improving the positive electrode utilization rate.

[0068] <Comparison of examples with different average thicknesses of flat metal tin> Next, the test results for No. 9 and No. 15 to No. 21 flooded lead-acid batteries are shown in Table 3, along with the positive electrode plate configuration of each flooded lead-acid battery (ratio of metallic tin to lead powder contained in the positive electrode mixture paste, average major axis diameter, average minor axis diameter, average aspect ratio, and average thickness). In other words, Table 3 summarizes the results of flooded lead-acid batteries using a positive electrode mixture paste containing 0.25 parts by mass of flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.05 μm to 1.50 μm per 100 parts by mass of lead powder.

[0069] [Table 3]

[0070] The results in Table 3 reveal the following: The No. 9 and No. 15 to No. 21 flooded lead-acid batteries, which used a positive electrode mixture paste containing 0.25 parts by mass of "flat metallic tin having an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.10 μm or more and 1.00 μm or less" per 100 parts by mass of lead powder, had improved positive electrode utilization (relative value was 102 or more) compared to the No. 1 flooded lead-acid battery, which used a positive electrode mixture paste that did not contain metallic tin. However, the positive electrode utilization of the No. 15 and No. 21 flooded lead-acid batteries, which used a positive electrode mixture paste containing 0.25 parts by mass of "flat metallic tin having an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.05 μm and 1.50 μm" per 100 parts by mass of lead powder, was the same as that of the No. 1 flooded lead-acid battery, which used a positive electrode mixture paste that did not contain metallic tin.

[0071] The reason for these results is thought to be that the average thickness of the "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction" contained in the positive electrode mixture paste at a ratio of 0.25 parts by mass per 100 parts by mass of lead powder was too thin in No. 15 flooded lead-acid battery and too thick in No. 21 flooded lead-acid battery, preventing the effect of the flat metallic tin from being obtained. If the average thickness of the flat metallic tin is too thin, it is likely to dissolve from the positive electrode mixture into the electrolyte during the formation of the battery container. As a result, in the No. 15 flooded lead-acid battery, the flat metallic tin was not present in the positive electrode mixture, which prevented it from providing electronic conductivity to the positive electrode active material, and therefore prevented it from improving the positive electrode utilization rate.

[0072] If the average thickness of the flat metallic tin is too thick, the specific surface area of ​​the flat metallic tin present in the pre-chemical positive electrode mixture in the positive electrode mixture filled plate (pre-chemical positive electrode plate) will be small. Then, metallic tin with a small specific surface area will not be effective in imparting electronic conductivity to the positive electrode active material in the post-chemical positive electrode mixture, and it is thought that the No. 21 flooded lead-acid battery did not achieve the effect of improving the positive electrode utilization rate. Furthermore, among No. 9 and No. 16 to No. 21 flooded lead-acid batteries, No. 17 to No. 19, which used a positive electrode mixture paste containing 0.25 parts by mass of "flat metallic tin with an average aspect ratio of 1.3 on the surface perpendicular to the thickness direction and an average thickness of 0.15 μm to 0.50 μm" per 100 parts by mass of lead powder, had a significant effect in improving the positive electrode utilization rate.

[0073] <Comparison of examples with different average aspect ratios of flat metal tin> Next, the test results for No. 18 and No. 22 to No. 25 flooded lead-acid batteries are shown in Table 4, along with the positive electrode plate configuration of each flooded lead-acid battery (ratio of metallic tin to lead powder contained in the positive electrode mixture paste, average major axis diameter, average minor axis diameter, average aspect ratio, and average thickness). That is, Table 4 summarizes the results of flooded lead-acid batteries using positive electrode mixture pastes containing 0.25 parts by mass of flat metallic tin with an average aspect ratio of 1.0 to 1.8 on the surface perpendicular to the thickness direction and an average thickness of 0.30 μm per 100 parts by mass of lead powder.

[0074] [Table 4]

[0075] The results in Table 4 reveal the following: The No. 18 and No. 23 to No. 25 flooded lead-acid batteries, which used a positive electrode mixture paste containing 0.25 parts by mass of "flat metallic tin having an average aspect ratio of 1.1 to 1.7 on the surface perpendicular to the thickness direction and an average thickness of 0.30 μm" per 100 parts by mass of lead powder, had improved positive electrode utilization (relative value of 102 or higher) compared to the No. 1 flooded lead-acid battery, which used a positive electrode mixture paste that did not contain metallic tin. However, the positive electrode utilization of the No. 22 and No. 25 flooded lead-acid batteries, which used a positive electrode mixture paste containing 0.25 parts by mass of "flat metallic tin having an average aspect ratio of 1.0 and 1.8 on the surface perpendicular to the thickness direction and an average thickness of 0.30 μm" per 100 parts by mass of lead powder, was the same as that of the No. 1 flooded lead-acid battery, which used a positive electrode mixture paste that did not contain metallic tin.

[0076] The reason for these results is thought to be that the average aspect ratio of the flat metallic tin with an average thickness of 0.30 μm, which was contained in the positive electrode mixture paste at a ratio of 0.25 parts by mass per 100 parts by mass of lead powder, was too small in the No. 22 flooded lead-acid battery and too large in the No. 25 flooded lead-acid battery, so that the effect of the flat metallic tin could not be obtained.

[0077] From the above, it was confirmed that a flooded lead-acid battery having a positive electrode plate obtained by filling the grid portion of a positive electrode current collector with a positive electrode mixture paste containing lead powder and "flat metallic tin having an average aspect ratio of the surfaces perpendicular to the thickness direction of 1.1 to 1.7 and an average thickness of 0.10 μm to 1.0 μm," in which "the ratio of the metallic tin to 100 parts by mass of lead powder is 0.10 parts by mass or more and less than 1.0 parts by mass," and then undergoing an aging and drying process, has a higher positive electrode utilization rate than a positive electrode mixture paste that does not contain the above additive ("flat metallic tin having an average aspect ratio of the surfaces perpendicular to the thickness direction of 1.1 to 1.7 and an average thickness of 0.10 μm to 1.0 μm," in which the ratio of the metallic tin to 100 parts by mass of lead powder is 0.10 parts by mass or more and less than 1.0 parts by mass). It was also confirmed that the ratio of metallic tin to 100 parts by mass of lead powder in the additive is preferably 0.20 parts by mass or more and 0.50 parts by mass or less, and that the average thickness of the additive is preferably 0.15 μm or more and 0.50 μm or less. [Explanation of symbols]

[0078] 1 Plate group 10 Positive electrode plate 12 Positive current collector plate lug 13 Positive strap 14 Positive terminal 20 negative electrode plate 22 Negative electrode current collector plate lug 23 Negative electrode strap 24 Negative terminal 30 Separator 41 Battery case 43 Lid

Claims

1. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte solution injected into the cell chamber; the electrode plate group has a stack including a plurality of alternately arranged positive electrode plates and negative electrode plates and separators arranged between the positive electrode plates and the negative electrode plates; the positive electrode plate includes a positive electrode current collector plate having a grid portion and a positive electrode mixture held in the grid portion, and is obtained by filling the grid portion with a positive electrode mixture paste and then carrying out an aging and drying process; The positive electrode mixture paste contains lead powder and flat metallic tin, the average thickness of the metallic tin is 0.10 μm or more and 1.0 μm or less, and the average aspect ratio of a plane perpendicular to the thickness direction of the metallic tin is 1.1 or more and 1.7 or less; A flooded lead-acid battery, wherein the ratio of the metallic tin to 100 parts by mass of the lead powder is 0.10 parts by mass or more and 0.90 parts by mass or less.

2. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte solution injected into the cell chamber; the electrode plate group has a stack including a plurality of alternately arranged positive electrode plates and negative electrode plates and separators arranged between the positive electrode plates and the negative electrode plates; the positive electrode plate includes a positive electrode current collector plate having a grid portion and a positive electrode mixture held in the grid portion, and is obtained by filling the grid portion with a positive electrode mixture paste and then carrying out an aging and drying process; The positive electrode mixture paste contains lead powder and flat metallic tin, the average thickness of the metallic tin is 0.10 μm or more and 1.0 μm or less, and the average aspect ratio of a plane perpendicular to the thickness direction of the metallic tin is 1.1 or more and 1.7 or less; A flooded lead-acid battery, wherein the ratio of the metallic tin to 100 parts by mass of the lead powder is 0.20 parts by mass or more and 0.50 parts by mass or less.

3. The battery includes a battery case having a cell chamber, a plate group housed in the cell chamber, and an electrolyte solution injected into the cell chamber; the electrode plate group has a stack including a plurality of alternately arranged positive electrode plates and negative electrode plates and separators arranged between the positive electrode plates and the negative electrode plates; the positive electrode plate includes a positive electrode current collector plate having a grid portion and a positive electrode mixture held in the grid portion, and is obtained by filling the grid portion with a positive electrode mixture paste and then carrying out an aging and drying process; The positive electrode mixture paste contains lead powder and flat metallic tin, the average thickness of the metallic tin is 0.15 μm or more and 0.50 μm or less, and the average aspect ratio of a plane perpendicular to the thickness direction of the metallic tin is 1.1 or more and 1.7 or less; A flooded lead-acid battery, wherein the ratio of the metallic tin to 100 parts by mass of the lead powder is 0.20 parts by mass or more and 0.50 parts 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 solution injected into the cell chamber; the electrode plate group has a stack including a plurality of alternately arranged positive electrode plates and negative electrode plates and separators arranged between the positive electrode plates and the negative electrode plates; The positive electrode plate includes a positive electrode current collector plate having a grid portion and a positive electrode mixture held by the grid portion, filling the grid-shaped portion with a positive electrode mixture paste; a step of performing aging and drying after the step to obtain a positive electrode mixture filled plate; a step of chemically converting the positive electrode mixture filled plate to obtain the positive electrode plate; Equipped with The positive electrode mixture paste may include: A method for manufacturing a flooded lead-acid battery using a material containing lead powder and flat metallic tin, wherein the metallic tin has an average thickness of 0.10 μm or more and 1.0 μm or less, an average aspect ratio of a surface perpendicular to a thickness direction of the metallic tin is 1.1 or more and 1.7 or less, and a ratio of the metallic tin to 100 parts by mass of the lead powder is 0.10 parts by mass or more and 0.90 parts by mass or less.

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