Bipolar battery

Abstract

To shorten a time required for an electrolyte injection process when manufacturing a bipolar battery in a method of injecting an electrolyte through an injection port provided in a frame that surrounds the side of a cell component after a structural assembly process is completed.SOLUTION: A separator 113 constituting a cell member of a bipolar battery is cut into a polygonal shape from a strip, and the strip has a different electrolyte permeation rate between the longitudinal direction, which is a machine flow direction during manufacturing, and the transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the strip, with the permeation rate in the longitudinal direction being faster than the transverse direction, and all sides constituting the separator polygon intersect with imaginary line segments parallel to the longitudinal direction MD. The bipolar battery has a frame that surrounds the side surfaces of the multiple cell members, and at least one of the multiple side plates constituting the frame is formed with a liquid inlet for the space.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a bipolar storage battery. [Background technology]

[0002] In recent years, the number of power generation facilities using natural energy such as solar and wind power has been increasing. Since it is not possible to control the amount of power generated in such power generation facilities, a storage battery is used to level the power load. That is, when the amount of power generated is greater than the amount of power consumed, the difference is charged to the storage battery, and when the amount of power generated is less than the amount of power consumed, the difference is discharged from the storage battery. Lead-acid batteries are widely used as the storage batteries from the viewpoints of economy, safety, and the like. For example, a bipolar storage battery described in Patent Document 1 below is known as such a conventional lead-acid battery.

[0003] This bipolar storage battery has a resin substrate attached to the inside of a picture-frame-shaped resin frame. Lead layers are arranged on both sides of the substrate. A positive electrode active material layer is adjacent to the lead layer on one side of the substrate, and a negative electrode active material layer is adjacent to the lead layer on the other side. The battery also has a frame-shaped resin spacer, inside which a glass mat impregnated with an electrolyte is arranged. Multiple frames and spacers are alternately stacked, and the frames and spacers are bonded together with an adhesive or the like. The lead layers on both sides of the substrate are connected via through holes in the substrate.

[0004] That is, the bipolar storage battery described in Patent Document 1 includes a positive electrode having a positive electrode current collector and a positive electrode active material layer, a negative electrode having a negative electrode current collector and a negative electrode active material layer, and a separator (glass mat) interposed between the positive electrode and the negative electrode, and has a plurality of cell members stacked and arranged with spaces between them, and a plurality of space-forming members that form a plurality of spaces to individually accommodate the plurality of cell members.

[0005] The space-forming member includes a substrate covering at least one of the positive and negative sides of the cell member and a frame (frames of the bipolar plates and end plates and spacers) surrounding the side surfaces of the cell member. Furthermore, the cell members and the substrates of the space-forming member are alternately stacked, the cell members are electrically connected in series, and the opposing surfaces of adjacent frames are joined to form the main body of the bipolar storage battery. The side plates of the main body are composed of the frames of multiple space-forming members.

[0006] The bipolar storage battery having the above structure can be produced, for example, by the following method. In advance, a liquid injection port (a hole for pouring electrolyte into each cell) or a recess constituting a liquid injection port is provided at a predetermined position on the frame body (a position that will be on the upper side of the main body during the electrolyte injection process) that penetrates toward each of the above-mentioned multiple spaces. First, the main body structural part is assembled. That is, multiple cell members and multiple space-forming member substrates are alternately stacked, the cell members are electrically connected in series, and the opposing surfaces of adjacent frames are joined together. Next, electrolyte is poured into each space through each filling port, impregnating the separator with the electrolyte. That is, in this method, the electrolyte injection step is performed after the main body structural part assembly step is completed.

[0007] On the other hand, the glass mat used as the separator is often a nonwoven fabric called AGM (Absorbent Glass Mat) whose main component is glass fiber. Patent Document 2 describes the following regarding a conventional method for producing a storage battery separator made of a wet-process paper sheet mainly made of glass fiber.

[0008] In conventional manufacturing methods using an inclined papermaking machine, the forming wire, which is the deposition surface of the glass fibers (i.e., the surface on which the glass fiber layer is formed), is moved while the paper is being made. As a result, as soon as one end of the fiber lands on the surface of the forming wire, the fiber is pulled in the direction of the moving forming wire. As a result, the fibers are oriented mostly in the direction of the moving forming wire, i.e., the length direction of the sheet, resulting in uneven fiber orientation in the longitudinal and transverse directions of the sheet (a state in which the fiber orientation has directionality). As a result, differences in the electrolyte absorption rate in the longitudinal and transverse directions of the sheet occur. Note that the longitudinal direction of the separator corresponds to the length direction of the product (machine direction: MD) during separator production, and the transverse direction of the separator corresponds to the width direction of the product during separator production.

[0009] The document also describes that by installing a pond regulator on a pool of a conventional inclined papermaking machine containing a papermaking raw material liquid in which glass fibers are dispersed in water, it is possible to obtain a glass fiber layer in which the fiber distribution of the glass fibers is uniform in the lengthwise and widthwise directions and the thickness direction, the fiber orientation is random in the lengthwise and widthwise directions (a state in which the fiber orientation has no direction), and the randomness of the fiber orientation in the lengthwise and widthwise directions is uniform in the thickness direction.

[0010] Specifically, the document describes a battery separator in which the average difference in liquid absorption speed between the vertical and horizontal directions of the separator (a separator having a width of 25 mm and a height of 10 cm or more is used as a sample, the bottom 1 cm of the sample is immersed in sulfuric acid with a specific gravity of 1.30 while the sample is held vertically, and the time required for the sulfuric acid to be absorbed up to 5 cm is measured) is 11% or less, and the average difference in liquid absorption speed between the front and back surfaces of the separator (a separator having a width of 25 mm and a height of 10 cm or more is used as a sample, the bottom 1 cm of the sample is immersed in sulfuric acid with a specific gravity of 1.30 while the time required for the sulfuric acid to be absorbed up to 5 cm is measured) is 17% or less. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 6124894 [Patent Document 2] Patent No. 4864457 Summary of the Invention [Problem to be solved by the invention]

[0012] In bipolar batteries with the above structure, the active material layer is prone to peeling and falling off from the current collector plate, so strong pressure is applied to the cell components to prevent this. Therefore, when manufacturing a bipolar battery with the above structure using the above method (a method in which the electrolyte injection process is performed after the assembly process of the main body structural parts is completed), it is difficult to impregnate the entire interior of the separator, which is in a compressed state, with the electrolyte during the electrolyte injection process. In particular, in large-capacity bipolar batteries with large separator areas, it takes a long time for the electrolyte to permeate the entire interior of the separator (especially to the center), so there is a demand for shortening the time required for the electrolyte injection process.

[0013] An object of the present invention is to shorten the time required for the electrolyte injection process when manufacturing a bipolar storage battery by using a method in which, after the structural assembly process is completed, an electrolyte injection process is performed through an injection port provided in a frame that surrounds the side surfaces of the cell components. [Means for solving the problem]

[0014] A first aspect of the present invention for solving the above problems is a bipolar storage battery having the following configurations (1) to (4). (1) A bipolar electrode including a current collecting member, a positive electrode active material layer formed on one surface of the current collecting member, and a negative electrode active material layer formed on the other surface of the current collecting member; a first end electrode disposed on the negative electrode active material layer side of the bipolar electrode and including a current collecting member and a positive electrode active material layer formed on one surface of the current collecting member; and a second end electrode disposed on the positive electrode active material layer side of the bipolar electrode and including a current collecting member and a negative electrode active material layer formed on one surface of the current collecting member. (2) The bipolar electrode is disposed between the first end electrode and the second end electrode, with the positive electrode active material layer of the bipolar electrode facing the negative electrode active material layer of the second end electrode, and the negative electrode active material layer of the bipolar electrode facing the positive electrode active material layer of the first end electrode, and a separator is disposed between the facing positive electrode active material layer and the negative electrode active material layer, thereby forming a plurality of cell members. The plurality of cell members are disposed in separate spaces. (3) The separator is cut into a polygonal shape from a strip, and the strip has a different permeation rate of the electrolyte in a longitudinal direction, which is the machine flow direction during production, and a transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the strip, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction. All sides constituting the polygon of the separator intersect with imaginary line segments parallel to the longitudinal direction. (4) A frame body is provided that surrounds the side surfaces of the plurality of cell members, and a liquid injection port for the space is formed in at least one of the side plates that constitute the frame body.

[0015] A second aspect of the present invention is a bipolar storage battery having the above-described configurations (1), (2), and (4) and the following configuration (11). (11) The separator is cut into a circular shape from a strip, and the strip has a different permeation rate of the electrolyte in the longitudinal direction, which is the machine flow direction during manufacturing, and in the transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the strip, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction.

[0016] A third aspect of the present invention is a bipolar storage battery having the above-described configurations (1), (2), and (4) and the following configuration (21). (21) The separator is composed of a plurality of stacked separator layers. Each of the separator layers is cut from a strip, and the strip has a different permeation rate of an electrolyte in a longitudinal direction, which is the machine direction during manufacturing, and a transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the strip, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction. In the stacked plurality of separator layers, one separator layer and at least one other separator layer intersect with each other at imaginary line segments parallel to the longitudinal direction. [Effects of the Invention]

[0017] According to the present invention, after the assembly process of the structural components is completed, the electrolyte is injected through an injection port provided in a frame that surrounds the side surfaces of the cell components, thereby shortening the time required for the electrolyte injection process when manufacturing a bipolar storage battery. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a bipolar storage battery according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] 2 is a perspective view showing the bipolar storage battery of FIG. 1 with the lid lifted off the main body. FIG. [Figure 4] 2 is a cross-sectional view of FIG. 1 taken along line B-B. [Figure 5] 2A and 2B are diagrams illustrating separators provided in cell members constituting the bipolar storage battery according to the embodiment. [Figure 6] 6 is a diagram illustrating another example of a separator provided in a cell member that constitutes a bipolar storage battery according to an embodiment, which is different from that shown in FIG. 5. FIG. [Figure 7] 6 is a diagram illustrating another example of a separator provided in a cell member that constitutes a bipolar storage battery according to an embodiment, which is different from that shown in FIG. 5. FIG. [Figure 8] 10A and 10B are diagrams illustrating a case where a separator provided in a cell member constituting a bipolar storage battery according to an embodiment is circular. [Figure 9]FIG. 10 is a diagram illustrating a separator provided in a cell member that constitutes a bipolar storage battery of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the following embodiments, limitations that are technically preferable for carrying out the present invention are imposed, but these limitations are not essential requirements of the present invention. In the following, a bipolar lead-acid battery will be described as an example of a bipolar storage battery.

[0020] [Overall structure] First, the overall configuration of the bipolar lead-acid battery of this embodiment will be described. As shown in Fig. 1, the bipolar lead-acid battery 100 of this embodiment is composed of a main body 101 and a lid 190. Fig. 1 shows the installed state of the bipolar lead-acid battery 100 during the electrolyte injection process, and the up-down direction of the main body 101 in this state is the X direction. The lid 190 is fixed to one end face of the main body 101 in the X direction (the upper face during the electrolyte injection process). In other words, the lid 190 is positioned at a position that will be the upper side of the main body 101 during the electrolyte injection process.

[0021] As shown in Fig. 2, the main body 101 has a plurality of cell members 110, a plurality of biplates (space-forming members) 120, a first end plate (space-forming member) 130, and a second end plate (space-forming member) 140. While Fig. 2 shows a bipolar lead-acid battery 100 in which three cell members 110 are stacked, the number of cell members 110 is determined by the battery design. In addition, the number of biplates 120 is determined according to the number of cell members 110. The stacking direction of the cell members 110 is the Z direction (the vertical direction in FIG. 2), and the direction perpendicular to the paper surface of FIG. 2 is the Y direction.

[0022] The cell member 110 includes a positive electrode 111, a negative electrode 112, and a separator consisting of two stacked rectangular (quadrilateral, polygonal) separator layers 113a, 113b. The separator layers 113a, 113b are impregnated with an electrolyte. The positive electrode 111 includes positive electrode current collectors 111a, 111aa made of lead foil and a positive electrode active material layer 111b. The negative electrode 112 includes negative electrode current collectors 112a, 112aa made of lead foil and a negative electrode active material layer 112b. The separator consisting of the two separator layers 113a, 113b is interposed between the positive electrode 111 and the negative electrode 112. In the cell member 110, positive electrode current collector plates 111a, 111aa, positive electrode active material layer 111b, separator layers 113a, 113b, negative electrode active material layer 112b, and negative electrode current collector plates 112a, 112aa are stacked in this order.

[0023] The dimension (thickness) in the Z direction is such that the positive electrode current collector 111a is larger (thicker) than the negative electrode current collector 112a, and the positive electrode active material layer 111b is larger (thicker) than the negative electrode active material layer 112b. The multiple cell members 110 are stacked and arranged at intervals in the Z direction, and the substrates 121 of the biplates 120 are arranged in these intervals. In other words, the multiple cell members 110 are stacked with the substrates 121 of the biplates 120 sandwiched between them.

[0024] The plurality of biplates 120, the first end plate 130, and the second end plate 140 are members (space forming members) for forming a plurality of spaces (cells) C that individually house a plurality of cell members 110. The biplate 120 comprises a substrate 121 having a rectangular planar shape, a frame 122 covering the four end faces of the substrate 121, and pillars 123 protruding perpendicularly from both sides of the substrate 121, and the substrate 121, frame 122, and pillars 123 are integrally formed from synthetic resin. The number of pillars 123 protruding from each side of the substrate 121 may be one or more.

[0025] In the Z direction, the dimension of the frame body 122 is larger than the dimension (thickness) of the substrate 121, and the dimension between the protruding end faces of the pillar portions 123 is the same as the dimension of the frame body 122. By stacking multiple biplates 120 with the frame bodies 122 and pillar portions 123 in contact with each other, a space C is formed between the substrates 121, and the dimension of the space C in the Z direction is maintained by the pillar portions 123 in contact with each other. The positive electrode current collector plates 111a, 111aa, the positive electrode active material layer 111b, the negative electrode current collector plates 112a, 112aa, the negative electrode active material layer 112b, and the separator layers 113a, 113b have through holes 111c, 111d, 112c, 112d, and 113c formed therein, respectively, for inserting the column portions 123.

[0026] The substrate 121 of the biplate 120 has a plurality of conductive holes 121a (through holes for arranging conductors that electrically connect adjacent cell components) penetrating the plate surface. A first recess 121b is formed on one surface of the substrate 121, and a second recess 121c is formed on the other surface. The first recess 121b is deeper than the second recess 121c. The dimensions of the first recess 121b and the second recess 121c in the X and Y directions correspond to the dimensions of the positive current collector plate 111a and the negative current collector plate 112a in the X and Y directions.

[0027] The substrate 121 of the biplate 120 is disposed between adjacent cell members 110 in the Z direction. The substrate 121 of the biplate 120 is a substrate that covers both the positive electrode 111 side of one cell member 110 and the negative electrode 112 side of the adjacent cell member 110. The positive electrode current collector 111a of the cell member 110 is disposed in a first recess 121b of the substrate 121 of the biplate 120 via an adhesive layer 150. In other words, the positive electrode current collector 111a is fixed to the surface of the substrate 121 on the positive electrode 111 side (the bottom surface of the first recess 121b) with an adhesive.

[0028] Furthermore, the negative electrode current collector 112a of the cell member 110 is disposed in the second recess 121c of the substrate 121 of the biplate 120 via the adhesive layer 150. That is, the negative electrode current collector 112a is fixed to the surface of the substrate 121 on the negative electrode 112 side (the bottom surface of the second recess 121c) with the adhesive. A conductor 160 is disposed in the conductive hole 121a of the substrate 121 of the biplate 120, and both end faces of the conductor 160 are in contact with and coupled to the positive current collector 111a and the negative current collector 112a. In other words, the positive current collector 111a and the negative current collector 112a are electrically connected by the conductor 160. As a result, all of the multiple cell members 110 are electrically connected in series.

[0029] The first end plate 130 comprises a substrate 131 that covers the positive electrode side of the cell member 110, a frame 132 that surrounds the side surface of the cell member 110, and a pillar 133 that protrudes perpendicularly from one surface of the substrate 131 (the surface facing the substrate 121 of the biplate 120 that is arranged closest to the positive electrode). The planar shape of the substrate 131 is rectangular, and the four end surfaces of the substrate 131 are covered with the frame 132, with the substrate 131, frame 132, and pillar 133 being integrally formed from a synthetic resin. The number of pillars 133 protruding from one surface of the substrate 131 may be one or more, and they should correspond to the pillars 123 of the biplate 120 that come into contact with the pillar 133.

[0030] In the Z direction, the dimension of frame body 132 is larger than the dimension (thickness) of substrate 131, and the dimension between the protruding end faces of column portion 133 is the same as the dimension of frame body 132. By stacking frame body 132 and column portion 133 in contact with frame body 122 and column portion 123 of biplate 120 arranged on the outermost side (positive electrode side), a space C is formed between substrate 121 of biplate 120 and substrate 131 of first endplate 130, and the dimension of space C in the Z direction is maintained by column portion 123 of biplate 120 and column portion 133 of first endplate 130, which are in contact with each other. The positive electrode current collector plate 111aa, positive electrode active material layer 111b, and separator layers 113a and 113b of the cell member 110 arranged on the outermost side (positive electrode side) have through holes 111c, 111d, and 113c formed therein, respectively, for allowing the columnar portion 133 to pass therethrough.

[0031] A recess 131b is formed on one surface of substrate 131 of first end plate 130. The dimension in the X direction of recess 131b corresponds to the dimension in the X direction of positive current collector 111aa. The dimension in the Z direction of positive current collector 111aa arranged on one surface of substrate 131 of first end plate 130 is larger than the dimension in the Z direction of positive current collector 111a arranged on one surface of substrate 121 of biplate 120. Positive electrode current collector 111aa of cell member 110 is placed in recess 131b of substrate 131 of first end plate 130 via adhesive layer 150. In other words, positive electrode current collector 111aa is fixed to the surface of substrate 131 on the positive electrode 111 side (the bottom surface of recess 131b) with adhesive. The first end plate 130 also includes a positive electrode terminal electrically connected to the positive electrode current collector plate 111aa in the recess 131b.

[0032] The second end plate 140 is composed of a substrate 141 that covers the negative electrode side of the cell member 110, a frame 142 that surrounds the side surface of the cell member 110, and a pillar portion 143 that protrudes perpendicularly from one surface of the substrate 141 (the surface facing the substrate 121 of the biplate 120 that is arranged on the most negative electrode side). The planar shape of the substrate 141 is rectangular, and the four end surfaces of the substrate 141 are covered with the frame 142, with the substrate 141, frame 142, and pillar portion 143 being integrally formed from a synthetic resin. The number of pillar portions 143 protruding from one surface of the substrate 141 may be one or more, and they should correspond to the pillar portions 123 of the biplate 120 that come into contact with the pillar portion 143.

[0033] In the Z direction, the dimension of frame body 142 is larger than the dimension (thickness) of substrate 131, and the dimension between the protruding end faces of two pillar portions 143 is the same as the dimension of frame body 142. By stacking frame body 142 and pillar portions 143 in contact with frame body 122 and pillar portions 123 of biplate 120 arranged on the outermost side (negative electrode side), a space C is formed between substrate 121 of biplate 120 and substrate 141 of second end plate 140, and the dimension of space C in the Z direction is maintained by pillar portions 123 of biplate 120 and pillar portions 143 of second end plate 140, which are in contact with each other. The negative electrode current collector plate 112aa, negative electrode active material layer 112b, and separator layers 113a, 113b of the cell member 110 arranged on the outermost side (negative electrode side) have through holes 112c, 112d, 113c formed therein, respectively, for allowing the column portion 143 to pass therethrough.

[0034] A recess 141b is formed on one surface of the substrate 141 of the second end plate 140. The dimensions of the recess 141b in the X and Y directions correspond to the dimensions of the negative current collector 112aa in the X and Y directions. The dimension in the Z direction of the negative current collector 112aa arranged on one surface of the substrate 141 of the second end plate 140 is larger than the dimension in the Z direction of the negative current collector 112a arranged on the other surface of the substrate 121 of the biplate 120. Negative electrode current collector 112aa of cell member 110 is placed in recess 141b of substrate 141 of second end plate 140 via adhesive layer 150. That is, negative electrode current collector 112aa is fixed to the surface of substrate 141 on the negative electrode 112 side (the bottom surface of recess 141b) with adhesive.

[0035] The second end plate 140 also includes a negative electrode terminal electrically connected to the negative electrode current collector plate 112aa in the recess 141b. Furthermore, the opposing surfaces of adjacent frame bodies 122, 132, 142 are joined together by vibration welding, and the biplate 120, first end plate 130, and second end plate 140 are integrated together. As can be seen from the above description, the biplate 120 is a space-forming member that includes a substrate 121 that covers both the positive electrode side and the negative electrode side of the cell member 110, and a frame 122 that surrounds the side surface of the cell member 110. The first end plate 130 is a space-forming member that includes a substrate 131 that covers only the positive electrode side (either the positive electrode side or the negative electrode side) of the cell member 110, and a frame 132 that surrounds the side surface of the cell member 110.

[0036] The second end plate 140 is a space-forming member that includes a substrate 141 that covers only the negative electrode side (either the positive electrode side or the negative electrode side) of the cell member 110, and a frame 142 that surrounds the side surface of the cell member 110. In other words, the substrates 121, 131, and 141 are substrates that cover at least one of the positive electrode side and the negative electrode side of the cell member 110, and the substrate 121 is a substrate that covers both the positive electrode side and the negative electrode side of the cell member 110. The substrate 121 of the biplate 120 is a substrate that is disposed between the cell members 110.

[0037] In the bipolar lead-acid battery 100 of the embodiment, a barrier electrode consisting of a substrate 121, a positive electrode current collector 111a, a negative electrode current collector 112a, a positive electrode active material layer 111b, and a negative electrode active material layer 112b is provided between a first end electrode consisting of a substrate 131, a positive electrode current collector 111aa, and a positive electrode active material layer 111b and a second end electrode consisting of a substrate 141, a negative electrode current collector 112aa, and a negative electrode active material layer 112b. The bipolar electrode is arranged such that the positive electrode active material layer 111b of the bipolar electrode faces the negative electrode active material layer 112b of the second end electrode, and the negative electrode active material layer 112b of the bipolar electrode faces the positive electrode active material layer 111b of the first end electrode, and a separator 113 is disposed between the facing positive electrode active material layer 111b and negative electrode active material layer 112b and stacked to form a plurality of cell members 110. The plurality of cell members 110 are arranged in individual spaces C.

[0038] [About the lid] 1 and 3, main body 101 has four side plates that form both ends in the X direction and both ends in the Y direction, and each side plate is formed by a side plate portion of frames 122, 132, and 142. Cover 109 is fixed onto the side plate that is located at one end of main body 101 in the X direction, that is, to one end face of main body 101 in the X direction. 3 and 4, three tubular liquid filling ports 180 are formed along the Y direction in the side plate that forms one end face in the X direction of the main body 101, and penetrate each of the spaces C. Each liquid filling port 180 is formed by a pair of opposing recesses 181. The recesses 181 penetrate the side plate of each of the frame bodies 122, 132, and 142 in the X direction, and are recessed in a semicircular arc shape from both end faces in the Z direction in the frame body 122, and are recessed in a semicircular arc shape from one end face in the Z direction in the frame bodies 132 and 142. 1 and 3, the lid 109 has electrolyte solution supply ports 191 at three positions along the Z direction at the center in the Y direction. As shown in Fig. 4, each of the liquid injection ports 180 extends along the X direction, and each of the electrolyte solution supply ports 191 is disposed directly above each of the liquid injection ports 180 disposed at the center in the Y direction.

[0039] [Separator details] 5, the "two stacked rectangular separator layers 113a, 113b" constituting the separator 113 are each cut into a rectangular shape from a strip, and the strip has a different permeation rate of the electrolyte in the machine direction (MD) during manufacturing and in the cross direction (CD) perpendicular to the machine direction and the thickness direction of the strip, with the permeation rate in the machine direction being faster than the cross direction. In other words, the separator layers 113a, 113b are cut out from a "wet-formed sheet primarily composed of glass fiber" formed by a method using an inclined papermaking machine, and are made of a nonwoven fabric primarily composed of glass fiber. In separator 113, that is, two stacked rectangular separator layers 113a and 113b, imaginary line segments parallel to the longitudinal direction MD of one separator layer 113a and the other separator layer 113b are perpendicular to each other. As a result, all end faces (positions of four sides S1 to S4) of rectangular separator 113 are provided with end faces of the strip in the longitudinal direction MD.

[0040] [Manufacturing method] The bipolar lead-acid battery 100 of this embodiment can be manufactured, for example, by a method including the steps described below.

[0041] <Manufacturing process of biplate with positive and negative current collector plates> First, the substrate 121 of the biplate 120 is placed on a workbench with the first recess 121b facing upward, adhesive is applied to the first recess 121b, and the positive current collector 111a is placed in the first recess 121b. At this time, the column portions 123 of the biplate 120 are passed through the through holes 111c of the positive current collector 111a. Next, the adhesive is cured to form an adhesive layer 150. As a result, the positive current collector 111a is attached to one surface of the substrate 121.

[0042] Next, the substrate 121 is placed on a workbench with the second recess 121c facing upward, and the conductor 160 is inserted into the conductive hole 121a. Next, adhesive is applied to the second recess 121c, and the negative current collector 112a is placed into the second recess 121c. At this time, the column portion 123 of the biplate 120 is passed through the through hole 112c of the negative current collector 112a. Next, the adhesive is hardened to form an adhesive layer 150. This allows the negative current collector 112a to be attached to the other surface of the substrate 121. Next, resistance welding is performed to connect the conductor 160 to the positive current collector 111a and the negative current collector 112a. This results in a biplate 120 (a biplate with positive and negative current collectors) in which the positive current collector 111a and the negative current collector 112a are fixed to both sides of the substrate 121. The required number of such biplates with positive and negative current collectors are prepared.

[0043] <Manufacturing process of end plates with positive current collector plates> The substrate 131 of the first end plate 130 is placed on a workbench with the recess 131b facing upward, adhesive is applied to the recess 131b, and the positive current collector 111aa is placed into the recess 131b. At this time, the column portions 133 of the end plate 130 are passed through the through holes 111c of the positive current collector 111aa. The adhesive is cured to form adhesive layer 150. This results in a first end plate 130 (end plate with a positive current collector) in which the positive current collector 111aa is fixed to one surface of the substrate 131.

[0044] <Manufacturing process of end plates with negative electrode current collector plates> The substrate 141 of the second end plate 140 is placed on a workbench with the recess 141b facing upward, adhesive is applied to the recess 141b, and the negative current collector 112aa is placed into the recess 141b. At this time, the column portions 143 of the second end plate 140 are passed through the through holes 112c of the negative current collector 112aa. The adhesive is cured to form adhesive layer 150. This results in a second end plate 140 (end plate with a negative current collector) in which the negative current collector 112aa is fixed to one surface of the substrate 141.

[0045] <The process of stacking and joining plates> First, the first end plate 130 to which the positive electrode current collector 111aa is fixed is placed on a workbench with the positive electrode current collector 111aa facing upward, and the positive electrode active material layer 111b is placed on the positive electrode current collector 111aa. At this time, the column portions 133 of the first end plate 130 are passed through the through holes 111d of the positive electrode active material layer 111b. Next, the two separator layers 113a and 113b and the negative electrode active material layer 112b are placed in this order on the positive electrode active material layer 111b.

[0046] Next, the biplate 120 to which the positive and negative electrode current collector plates are fixed is placed, with the negative electrode current collector plate 112a side facing downward, on the first end plate 130 in this state. At this time, the column portions 123 of the biplate 120 are passed through the through holes 113c of the two separator layers 113a and 113b and the through hole 112d of the negative electrode active material layer 112b, and the biplate 120 is placed on the column portions 133 of the first end plate 130, and the frame 122 of the biplate 120 is placed on the frame 132 of the first end plate 130.

[0047] In this state, first end plate 130 is fixed, and vibration welding is performed while vibrating biplate 120 in the diagonal direction of substrate 121. As a result, frame 122 of biplate 120 is joined onto frame 132 of first end plate 130, and column portions 123 of biplate 120 are joined onto column portions 133 of first end plate 130. As a result, the biplate 120 is joined onto the first end plate 130, the cell member 110 is placed in the space C formed by the first end plate 130 and the biplate 120, and the positive electrode current collector plate 111a is exposed on the upper surface of the biplate 120.

[0048] Next, the positive electrode active material layer 111b, two separator layers 113a and 113b, and negative electrode active material layer 112b are placed in this order on the combined assembly thus obtained, in which the biplate 120 is joined to the first end plate 130, and then another biplate 120 with positive and negative electrode current collector plates is placed with the negative electrode current collector plate 112a side facing downwards. In this state, the combined body is fixed, and vibration welding is performed while vibrating the biplate 120 with the separate positive and negative electrode current collector plates in the diagonal direction of the substrate 121. This vibration welding process is continued until the required number of biplates 120 are joined onto the first end plate 130.

[0049] Finally, the positive electrode active material layer 111b, the two separator layers 113a, 113b, and the negative electrode active material layer 112b are placed in this order on the uppermost biplate 120 of the combined assembly in which all the biplates 120 are joined, and then the second end plate 140 is placed with the negative electrode current collector plate 112aa side facing downwards. In this state, the combined body is fixed, and vibration welding is performed while vibrating the second end plate 140 in the diagonal direction of the substrate 141. As a result, the second end plate 140 is joined onto the uppermost biplate 120 of the combined body to which all the biplates 120 have been joined.

[0050] By carrying out the above steps, the cell members and the substrates of the space forming members are alternately stacked, the cell members are electrically connected in series, and the opposing surfaces of adjacent frames are joined together. In other words, the structural part of the main body 101 can be assembled. In the above explanation, the stacking order is described as being from the first end plate 130 to the second end plate 140, but the stacking order may also be reversed, from the second end plate 140 to the first end plate 130.

[0051] <Process for fixing the lid to the main body> In the structural part of the main body 101 assembled as described above, circular liquid injection ports 180 are formed by recesses 181 in the opposing frames at the positions of the spaces C in the side plates located at one end of the main body 101 in the X direction. 3, this main body 101 is placed with the surface on which the liquid inlet 180 is formed (one end surface in the X direction) facing up, and the lid 190 is placed on top of it so that the electrolyte supply port 191 is aligned with the liquid inlet 180 at the center of the main body 101 in the Y direction, and the lid 190 is fixed to the main body 101. This results in the state shown in FIG.

[0052] <Electrolyte injection process> Next, in the state shown in FIG. 1, the electrolyte is supplied from each of the electrolyte supply ports 191 of the lid 190. 4, the electrolyte supplied to each electrolyte supply port 191 of the lid 190 enters a passage formed between the lid 190 and the main body 101, then enters each space C through the three liquid inlets 180, and is supplied to the separator 113 of the cell member 110 arranged in the space C. At this time, the electrolyte that has entered each space C from the three liquid inlets 180 flows inward from the four side surfaces of the separator 113 (end surfaces corresponding to the four sides S1 to S4 of the rectangle). <Chemical conversion process> Finally, the bipolar lead-acid battery 100 is obtained by forming the battery under predetermined conditions.

[0053] [Action, effect] As described above, in the bipolar lead-acid battery 100 of the embodiment, the end faces of the strip-shaped material in the longitudinal direction MD are present on all end faces (positions of the four sides S1 to S4) of the rectangular separator 113, so that the electrolyte can easily flow from the side faces of the separator 113 to the inside of the separator 113 not only in the X direction but also in the Y direction. Therefore, according to the bipolar lead-acid battery 100 of the embodiment, the time required for the electrolyte injection process can be reduced compared to when a separator is used in which the end face of the strip in the longitudinal direction MD is present on only a portion of the end face of the separator (when the other aspects are the same configuration). Furthermore, in the bipolar lead-acid battery 100 of the embodiment, the MD of one of the two separator layers is aligned with the extension direction of the liquid inlet. This allows for a reduction in the time required for the electrolyte injection process compared to a case where the extension direction of the liquid inlet and the MDs of both separator layers are not aligned (when the other aspects are the same).

[0054] 〔others〕 In the bipolar lead-acid battery 100 of the embodiment, the two separator layers 113a, 113b are stacked so that imaginary line segments parallel to the respective MDs (vertical directions) are perpendicular to each other, that is, so that the intersection angle between the imaginary line segments is 90°. However, as long as the imaginary line segments intersect with each other, the intersection angle may be deviated from 90°. Although the bipolar lead-acid battery 100 of the embodiment is provided with a rectangular separator 113, the shape of the separator may be a polygon other than a rectangular shape.

[0055] In the bipolar lead-acid battery 100 of the embodiment, the MD (longitudinal direction) of the separator layer 113a is parallel to two sides S2 and S4 of the rectangle forming the separator 113, and an imaginary line segment (hereinafter simply referred to as "MD") parallel to the MD of the separator layer 113b is parallel to two sides S1 and S3 of the rectangle forming the separator 113. However, the MD and the sides do not have to be parallel. An example is shown in FIG. 6. In the example of FIG. 6, the MD and the diagonal of the rectangle are parallel, and the imaginary line segments parallel to the MD of the separator layer 113a and the separator layer 113b are perpendicular to each other.

[0056] However, when producing the separator layers 113a and 113b by cutting a long strip separator in the machine direction MD, two separator layers 113a and 113b with two sides parallel to MD can be produced by cutting the strip separator perpendicular to MD. On the other hand, when producing separator layers with two sides that are not parallel to MD by cutting from a strip separator, the cutting process becomes complicated. Therefore, from the viewpoint of manufacturing costs, it is preferable to use separator layers with two sides parallel to MD.

[0057] 7, two separator layers 113a, 113b are stacked so that their MDs are parallel to each other to form separator 113. One diagonal line is parallel to the MDs of the two separator layers 113a, 113b. In this example, separator 113 has one diagonal line parallel to the MD, and the four sides S1 to S4 of the rectangle that forms separator 113 intersect with imaginary line segments that are parallel to the vertical direction. Note that a separator with one diagonal parallel to the MD, as in the example of Figure 7, can also be constructed from a single separator "made of a nonwoven fabric primarily composed of glass fiber" whose thickness is the total thickness of two separator layers 113a and 113b. In this single separator, as in separator 113 of Figure 7, the four sides S1 to S4 of the rectangle constituting separator 113 intersect with imaginary lines parallel to the vertical direction. As a result, the vertical end faces of the strip-shaped material exist on all end faces of the single separator.

[0058] This single separator corresponds to the separator that constitutes the bipolar storage battery of the first embodiment of the present invention, but does not correspond to the separator that constitutes the bipolar storage battery of the third embodiment of the present invention. In contrast, the separator 113 shown in Figures 5 to 7 not only corresponds to the separator that constitutes the bipolar storage battery of the third embodiment of the present invention, but also corresponds to the separator that constitutes the bipolar storage battery of the first embodiment of the present invention, since the four sides S1 to S4 of the rectangle that constitutes the separator 113 intersect with imaginary line segments parallel to the vertical direction.

[0059] The separator 113 shown in FIG. 8 is a strip-shaped separator, i.e., a strip-shaped separator in which the electrolyte permeation rate differs between the machine direction (MD) during manufacturing and the cross direction (CD) perpendicular to the machine direction and thickness direction, with the permeation rate in the machine direction being faster than the cross direction, and corresponds to the separator constituting the cell member of the second embodiment.

[0060] In the case of a circular separator, not only when the MD (longitudinal direction) is arranged parallel to the Y direction as shown in Fig. 8(a) but also when the MD is arranged parallel to the X direction as shown in Fig. 8(b), the end face of the longitudinal direction MD of the strip is located outside the center line in the Y direction. Therefore, even if the direction in which the liquid inlet extends (X direction) does not coincide with the MD, the electrolyte is likely to flow from the side surface of the separator 113 into the inside of the separator 113 not only in the X direction but also in the Y direction. Therefore, in the case of a circular separator, it is not essential to align the MD with the direction in which the liquid inlet extends (X direction), as is the case with a polygonal separator.

[0061] Furthermore, when a separator is formed by stacking a plurality of circular separator layers, the layers may be stacked so that the MDs are parallel to each other, or so that the MDs are crossed. Although the rectangular positive electrode 111 is shown by a two-dot chain line in Figure 8, it is desirable for the separator to cover the entire positive electrode and negative electrode, so when using a circular separator 113 and a rectangular (polygonal) positive electrode 111 (and negative electrode), the size of the circular separator 113 is made larger than the circumscribed circle of the positive electrode 111 (and negative electrode).

[0062] In addition, in this embodiment, a bipolar lead-acid battery using lead for the current collector plate has been described as an example of a bipolar storage battery, but the bipolar storage battery of the present invention may also be a bipolar storage battery using a metal other than lead for the current collector plate. In the bipolar storage battery of this embodiment, the current collecting members of the bipolar electrodes constituting the bipolar storage battery of the present invention are composed of a substrate 121 of a biplate 120, a positive current collecting plate 111a fixed to one surface of the substrate 121, and a negative current collecting plate 112a fixed to the other surface of the substrate 121.

[0063] In the bipolar storage battery of this embodiment, the current collecting member of the first end electrode constituting the bipolar storage battery of the present invention is composed of a substrate 131 of the first end plate 130 and a positive electrode current collecting plate 111aa fixed to one surface of the substrate 131. In the bipolar storage battery of this embodiment, the current collecting member of the second end electrode constituting the bipolar storage battery of the present invention is composed of a substrate 141 of the second end plate 140 and a negative electrode current collecting plate 112aa fixed to one surface of the substrate 141.

[0064] The bipolar storage battery of this embodiment includes a plurality of cell members each including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a plurality of space-forming members each forming a plurality of spaces for individually accommodating the plurality of cell members. The space-forming member includes a substrate covering at least one of the positive electrode side and the negative electrode side of the cell member and a frame body surrounding a side surface of the cell member, the cell members and the substrates of the space-forming members being arranged in an alternate stacked state, the plurality of cell members being electrically connected in series, and opposing surfaces of adjacent frames being joined to form a main body, the main body having a plurality of side plates formed by side plate portions of the plurality of frames, and at least one of the plurality of side plates being formed with a liquid filling port for each of the plurality of spaces.

[0065] Another embodiment of the bipolar storage battery of the present invention is a bipolar storage battery that does not include a substrate having positive and negative current collectors fixed to both sides, but has a bipolar electrode in which a positive active material layer is formed on one side of a current collector that also serves as a positive current collector and a negative current collector, and a negative active material layer is formed on the other side of the current collector. In this case, the current collecting member of the first end electrode constituting the bipolar storage battery of the present invention is the positive current collector, and the current collecting member of the second end electrode constituting the bipolar storage battery of the present invention is the negative current collector. [Example]

[0066] The present invention will be further described below with reference to specific examples. First, a 1 mm thick strip of AGM manufactured by Entech Asia Co., Ltd. was prepared as a separator layer, and the electrolyte penetration time was measured in both the MD direction, which is parallel to the length of the strip, and the CD direction, which is perpendicular to the MD. Specifically, the prepared AGM was cut into strips 15 mm wide and 300 mm long with the MD parallel to the length to prepare MD test pieces, and cut into strips 15 mm wide and 300 mm long with the CD parallel to the length to prepare CD test pieces. Each test piece was oriented with its length aligned vertically, and the bottom 1 cm was immersed in colored dilute sulfuric acid with a specific gravity of 1.25. The time it took for the sulfuric acid to penetrate to heights of 5, 10, 15, 20, and 25 cm from the bottom was measured. The results are shown in Table 1.

[0067] [Table 1]

[0068] As can be seen from Table 1, the time taken to reach a height of 10 cm was the same for MD and CD, but the time taken to reach 5 cm, 15 cm, 20 cm, and 25 cm was about 10% faster for MD than for CD. Next, the same AGM was cut into squares with sides of 300 mm each to prepare numerous test pieces. The cutting was performed so that the MD was parallel to a pair of opposing sides. This also resulted in the CD being parallel to the other two sides. Two test pieces were then stacked vertically in the combinations shown in Table 2, and dummy bipolar lead-acid battery cell components were assembled using transparent resin plates except for the separator.

[0069] Regarding the stacking state of the separator layers, No. 1 is the state shown in Fig. 5, No. 2 is the state shown in Fig. 9, and No. 3 is the state in which separator 113 is rotated 90° within the plane of Fig. 9. That is, in No. 1, the imaginary line segment parallel to MD intersects with all four sides (all sides) of the rectangle forming separator 113, while in No. 2 and No. 3, the imaginary line segment parallel to MD intersects with only two sides of the rectangle forming separator 113. The assembled cell member was set in a liquid injection device in which gaps of the same dimensions were provided on the top, bottom, left and right sides, and the boundary between the two separator layers, which was the center of the upper width direction, was aligned with the center of the liquid injection port located above, and the electrolyte was injected through the liquid injection port, and the time required for the electrolyte to penetrate the separator and reach the center was measured.

[0070] That is, in No. 1, two separator layers are stacked so that their MDs are perpendicular to each other and the direction of extension of the MD and the liquid inlet is aligned, in No. 2, two separator layers are stacked so that their MDs are parallel to each other and the direction of extension of the MD and the liquid inlet is aligned, and in No. 3, two separator layers are stacked so that their MDs are parallel to each other and the direction of extension of the CD and the liquid inlet is aligned.

[0071] [Table 2]

[0072] As can be seen from Table 2, Nos. 1 and 2, in which the vertical direction (pouring direction) of at least one separator layer coincided with the MD of the separator, reached the center 29 and 23 seconds faster, respectively, than No. 3, in which neither of the two separator layers coincided. Furthermore, No. 1, in which only one separator layer coincided, reached the center 6 seconds faster than No. 2, in which both separator layers coincided, because the electrolyte was more likely to permeate from the left and right sides as well as from above where the pouring port is located. This difference of 6 seconds is significant when mass-producing cell components for bipolar batteries and cannot be ignored, contributing to valuable savings in work time. [Explanation of symbols]

[0073] 100 Bipolar lead-acid battery (bipolar battery) 101 Main Unit 110 Cell member 111 Positive electrode 112 Negative electrode 111a Positive current collector plate 112a Negative current collector plate 111b Positive electrode active material layer 112b Negative electrode active material layer 113 Separator 113a Separator layer 113b separator layer 120 Biplate (space forming member) 121 Biplate substrate 121a Conduction hole on the board 121b First recess of substrate 121c second recess in the substrate 122 Biplate frame 130 First end plate (space forming member) 131 First end plate substrate 132 First end plate frame 140 Second end plate (space forming member) 141 Second end plate substrate 142 Second end plate frame 150 Adhesive layer 160 Conductor 180 Filling port 181 A pair of recesses forming a liquid inlet 190 Lid 191 Electrolyte supply port C. Space (space for accommodating cells and cell components) MD Machine flow direction during manufacturing (longitudinal direction) CD horizontal

Claims

1. a bipolar electrode including a current collecting member, a positive electrode active material layer formed on one surface of the current collecting member, and a negative electrode active material layer formed on the other surface of the current collecting member; a first end electrode disposed on the negative electrode active material layer side of the bipolar electrode, the first end electrode including a current collecting member and a positive electrode active material layer formed on one surface of the current collecting member; and a second end electrode disposed on the positive electrode active material layer side of the bipolar electrode, the second end electrode including a current collecting member and a negative electrode active material layer formed on one surface of the current collecting member; and the bipolar electrode is disposed between the first end electrode and the second end electrode, with the positive electrode active material layer of the bipolar electrode and the negative electrode active material layer of the second end electrode facing each other, and with the negative electrode active material layer of the bipolar electrode and the positive electrode active material layer of the first end electrode facing each other, and a separator is disposed between the facing positive electrode active material layer and the facing negative electrode active material layer and stacked to form a plurality of cell members, and the plurality of cell members are disposed in individual spaces; the separator is cut into a polygonal shape from a strip, and the strip has a different permeation rate of an electrolyte in a longitudinal direction, which is a machine flow direction during production, and a transverse direction, which is perpendicular to the longitudinal direction and a thickness direction of the strip, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction; all sides constituting the polygon of the separator intersect with the imaginary line segment parallel to the vertical direction, a bipolar storage battery having a frame that surrounds the side surfaces of the plurality of cell members, and a liquid filling port for the space formed in at least one of the side plates that constitute the frame;

2. a bipolar electrode including a current collecting member, a positive electrode active material layer formed on one surface of the current collecting member, and a negative electrode active material layer formed on the other surface of the current collecting member; a first end electrode disposed on the negative electrode active material layer side of the bipolar electrode, the first end electrode including a current collecting member and a positive electrode active material layer formed on one surface of the current collecting member; and a second end electrode disposed on the positive electrode active material layer side of the bipolar electrode, the second end electrode including a current collecting member and a negative electrode active material layer formed on one surface of the current collecting member; and the bipolar electrode is disposed between the first end electrode and the second end electrode, with the positive electrode active material layer of the bipolar electrode and the negative electrode active material layer of the second end electrode facing each other, and with the negative electrode active material layer of the bipolar electrode and the positive electrode active material layer of the first end electrode facing each other, and a separator is disposed between the facing positive electrode active material layer and the facing negative electrode active material layer and stacked to form a plurality of cell members, and the plurality of cell members are disposed in individual spaces; the separator is cut into a circular shape from a strip, the electrolytic solution permeation rate in the longitudinal direction, which is the machine flow direction during production, of the web is different from the electrolytic solution permeation rate in the transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the web, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction; a bipolar storage battery having a frame that surrounds the side surfaces of the plurality of cell members, and a liquid filling port for the space formed in at least one of the side plates that constitute the frame;

3. a bipolar electrode including a current collecting member, a positive electrode active material layer formed on one surface of the current collecting member, and a negative electrode active material layer formed on the other surface of the current collecting member; a first end electrode disposed on the negative electrode active material layer side of the bipolar electrode, the first end electrode including a current collecting member and a positive electrode active material layer formed on one surface of the current collecting member; and a second end electrode disposed on the positive electrode active material layer side of the bipolar electrode, the second end electrode including a current collecting member and a negative electrode active material layer formed on one surface of the current collecting member; and the bipolar electrode is disposed between the first end electrode and the second end electrode, with the positive electrode active material layer of the bipolar electrode and the negative electrode active material layer of the second end electrode facing each other, and with the negative electrode active material layer of the bipolar electrode and the positive electrode active material layer of the first end electrode facing each other, and a separator is disposed between the facing positive electrode active material layer and the facing negative electrode active material layer and stacked to form a plurality of cell members, and the plurality of cell members are disposed in individual spaces; the separator is made up of a plurality of stacked separator layers, the separator layers are each cut out from a strip; the electrolytic solution permeation rate in the longitudinal direction, which is the machine flow direction during production, of the web is different from the electrolytic solution permeation rate in the transverse direction, which is perpendicular to the longitudinal direction and the thickness direction of the web, and the permeation rate in the longitudinal direction is faster than the permeation rate in the transverse direction; In the stacked separator layers, one separator layer and at least one other separator layer are arranged such that imaginary line segments parallel to the longitudinal direction intersect with each other, a bipolar storage battery having a frame that surrounds the side surfaces of the plurality of cell members, and a liquid filling port for the space formed in at least one of the side plates that constitute the frame;

4. In the plurality of stacked separator layers, the imaginary line segments of one separator layer and at least one other separator layer are perpendicular to each other, 4. The bipolar storage battery according to claim 3, wherein the liquid inlet is tubular, and the direction in which the liquid inlet extends coincides with the longitudinal direction of any one of the plurality of separator layers.

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