Bipolar lead-acid battery

Abstract

To efficiently manufacture a highly durable biplate for a bipolar lead-acid battery, which is manufactured by bringing both end faces of a conductor arranged in a through-hole of a substrate into contact with a positive electrode current collector plate and a negative electrode current collector plate arranged on both sides of the substrate and joining them by a method such as resistance welding.SOLUTION: A bipolar lead-acid battery includes a substrate 121 arranged between adjacent cell members 110, the substrate 121 includes a through hole 121a in the thickness direction, a conductor 160 arranged in the through hole 121a, a positive current collector 111a that constitutes one of the cell members 110 arranged on one side of the substrate 121, and a negative current collector 112a that constitutes the other cell member 110 arranged on the other side, both end faces of the conductor 160 joined to the positive current collector 111a and the negative current collector 112a, respectively, and the positive current collector 111a and the conductor 160 are formed from a lead alloy having the same components.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bipolar lead-acid 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 lead-acid battery described in Patent Document 1 below is known as such a conventional lead-acid battery.

[0003] This bipolar lead-acid 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 lead-acid 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) present 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. 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 lead-acid battery.

[0006] Patent Document 1 describes the use of lead foil as the lead layers placed on both sides of the substrate, but does not describe the specific composition of the lead foil to be used. It also describes the electrically connecting the lead layers on both sides of the substrate by resistance welding via through holes provided in the substrate, but does not describe placing a conductor separate from the lead layers on both sides of the substrate in these through holes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6124894 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to efficiently manufacture a highly durable biplate for a bipolar lead-acid battery, which is manufactured by bringing both end faces of a conductor arranged in a through hole of a substrate into contact with a positive current collector plate and a negative current collector plate arranged on both sides of the substrate and joining them by a method such as resistance welding. [Means for solving the problem]

[0009] A first aspect of the present invention for solving the above problems is a biplate for a bipolar lead-acid battery having the following configurations (1) and (2).

[0010] (1) A bipolar lead-acid battery includes a substrate disposed between adjacent cell members. The substrate has a through hole in the thickness direction, and a conductor is disposed in the through hole. A positive current collector that constitutes one of the cell members is disposed on one side of the substrate, and a negative current collector that constitutes the other cell member is disposed on the other side of the substrate. Both end faces of the conductor are joined to the positive current collector and the negative current collector, respectively.

[0011] (2) The positive electrode current collector and the conductor are made of the same lead alloy, where the components refer to the main elements constituting the lead alloy and do not include elements such as inevitable impurities.

[0012] A second aspect of the present invention is a biplate for a bipolar lead-acid battery having the above configuration (1) and the following configuration (3).

[0013] (3) The positive electrode current collector, the negative electrode current collector, and the conductor are made of the same lead alloy, where the components refer to the main elements constituting the lead alloy and do not include elements such as inevitable impurities.

[0014] A third aspect of the present invention is a biplate for a bipolar lead-acid battery having the above configuration (1) and the following configuration (4).

[0015] (4) The positive electrode current collector and the conductor are formed of the same lead alloy, where the composition refers to the proportion of the main elements constituting the lead alloy, excluding the proportion of elements such as unavoidable impurities.

[0016] A fourth aspect of the present invention is a biplate for a bipolar lead-acid battery having the above configuration (1) and the following configuration (5).

[0017] (5) The positive electrode current collector, the negative electrode current collector, and the conductor are formed of the same lead alloy, where the composition refers to the proportion of the main elements constituting the lead alloy, excluding the proportion of elements such as unavoidable impurities. [Effects of the Invention]

[0018] According to the biplate for a bipolar lead-acid battery of the present invention, the rate of defects is reduced when both end faces of the conductor arranged in the through hole of the substrate are brought into contact with the positive and negative current collector plates arranged on both sides of the substrate and joined by a method such as resistance welding. Therefore, the biplate for a bipolar lead-acid battery and the bipolar lead-acid battery of the present invention are expected to be efficiently manufactured with excellent durability. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing a bipolar lead-acid 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. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] [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 disposed at a position that will be the upper side of the main body 101 during the electrolyte injection process. The lid 190 has electrolyte supply ports 191 at three locations along the Z direction at the center in the Y direction. Each electrolyte supply port 191 is disposed directly above one of the multiple injection ports formed in the main body 101 that is disposed at the center in the Y direction.

[0022] 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.

[0023] 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. The cell member 110 includes a positive electrode 111, a negative electrode 112, and a stacked separator 113. The positive electrode 111 includes positive electrode lead foils (positive electrode current collector plates) 111a and 111aa and a positive electrode active material layer 111b. The negative electrode 112 includes negative electrode lead foils (negative electrode current collector plates) 112a and 112aa and a negative electrode active material layer 112b. The separator 113 is located between the positive electrode 111 and the negative electrode 112. In the cell member 110, the positive electrode lead foils 111a and 111aa, the positive electrode active material layer 111b, the separator 113, the negative electrode active material layer 112b, and the negative electrode lead foils 112a and 112aa are stacked in this order.

[0024] The positive electrode lead foil 111a and the negative electrode lead foil 112a have the same dimension (thickness) in the Z direction, but 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.

[0025] 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.

[0026] 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.

[0027] The substrate (main substrate) 121 of the biplate 120 has a plurality of through holes 121a in the thickness direction within its 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 in the X and Y directions of the first recess 121b and the second recess 121c correspond to the dimensions in the X and Y directions of the positive electrode lead foil 111a and the negative electrode lead foil 112a.

[0028] 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 lead foil 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 lead foil 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.

[0029] Furthermore, the negative electrode lead foil 112a of the cell member 110 is placed in the second recess 121c of the substrate 121 of the biplate 120 via the adhesive layer 150. That is, the negative electrode lead foil 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.

[0030] A conductor 160 is disposed in the through-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 electrode lead foil 111a and the negative electrode lead foil 112a, respectively. In other words, the positive electrode lead foil 111a and the negative electrode lead foil 112a are connected by the conductor 160. As a result, all of the multiple cell members 110 are electrically connected in series.

[0031] 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.

[0032] 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.

[0033] A recess 131b is formed on one surface of the substrate 131 of the first end plate 130. The X-direction dimension of the recess 131b corresponds to the X-direction dimension of the positive electrode lead foil 111aa. The Z-direction dimension of the positive electrode lead foil 111aa arranged on one surface of the substrate 131 of the first end plate 130 is larger than the Z-direction dimension of the positive electrode lead foil 111a arranged on one surface of the substrate 121 of the biplate 120.

[0034] The positive electrode lead foil 111aa of the cell member 110 is placed in the recess 131b of the substrate 131 of the first end plate 130 via the adhesive layer 150. That is, the positive electrode lead foil 111aa is fixed to the surface of the substrate 131 on the positive electrode 111 side (the bottom surface of the recess 131b) with the adhesive. The first end plate 130 also includes a positive electrode terminal electrically connected to the positive electrode lead foil 111aa in the recess 131b.

[0035] 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.

[0036] 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.

[0037] A recess 141b is formed on one surface of the substrate 141 of the second end plate 140. The X and Y dimensions of the recess 141b correspond to the X and Y dimensions of the negative electrode lead foil 112aa. The Z dimension of the negative electrode lead foil 112aa arranged on one surface of the substrate 141 of the second end plate 140 is larger than the Z dimension of the negative electrode lead foil 112a arranged on the other surface of the substrate 121 of the biplate 120.

[0038] The negative electrode lead foil 112aa of the cell member 110 is placed in the recess 141b of the substrate 141 of the second end plate 140 via the adhesive layer 150. That is, the negative electrode lead foil 112aa is fixed to the surface of the substrate 141 on the negative electrode 112 side (the bottom surface of the recess 141b) with the adhesive. The second end plate 140 also includes a negative electrode terminal electrically connected to the negative electrode lead foil 112aa in the recess 141b.

[0039] Furthermore, holes (hereinafter referred to as "insertion holes") 111c, 111d, 112c, 112d, and 113c are formed in the positive electrode lead foils 111a and 111aa, the positive electrode active material layer 111b, the negative electrode lead foils 112a and 112aa, the negative electrode active material layer 112b, and the separator 113, respectively, penetrating in the thickness direction for inserting the corresponding column portions 123, 133, and 143. The corresponding column portions 123, 133, and 143 are inserted into the insertion holes 111c, 111d, 112c, 112d, and 113c, respectively.

[0040] Furthermore, the opposing surfaces of adjacent frame bodies 122, 132, 142 are joined 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.

[0041] 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 (main substrate) that is disposed between the cell members 110.

[0042] [Regarding lead alloys that form positive and negative current collectors and conductors] The positive electrode current collector 111a, the negative electrode current collector 112a, and the conductor 160 are formed of the same lead alloy. This lead alloy has a calcium (Ca) content of 0.01% by mass or more and 0.1% by mass or less, a tin (Sn) content of 1.5% by mass or more and 2.0% by mass or less, and the remainder being lead and unavoidable impurities. The positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 all have a rolled texture (also called a "striped texture" or "fibrous texture"). The rolled texture is harder than a granular texture (also called a "cast texture").

[0043] [Manufacturing method] The bipolar lead-acid battery 100 of this embodiment can be manufactured, for example, by a method including the steps described below.

[0044] <Production process of biplate with lead foil for positive and negative electrodes> First, the substrate 121 of the biplate 120 is placed on a workbench with the first recess 121b facing up, adhesive is applied to the first recess 121b, and the positive electrode lead foil 111a is inserted into the first recess 121b. At this time, the column portion 123 of the biplate 120 is passed through the insertion hole 111c of the positive electrode lead foil 111a. In addition, a mask is applied to prevent the adhesive from entering the through hole 121a. Next, the adhesive is hardened to form an adhesive layer 150. This allows the positive electrode lead foil 111a to be attached to one surface of the substrate 121.

[0045] Next, the substrate 121 is placed on a workbench with the second recess 121c facing up, and after removing the masking, the conductor 160 is inserted into the through-hole 121a so that one end surface of the conductor 160 contacts the positive electrode lead foil 111a. Next, adhesive is applied to the second recess 121c, and the negative electrode lead foil 112a is placed in the second recess 121c. At this time, the column portion 123 of the biplate 120 is passed through the insertion hole 112c of the negative electrode lead foil 112a. Also, care is taken not to allow adhesive to adhere to the top surface of the conductor 160.

[0046] Next, the adhesive is cured to form an adhesive layer 150. As a result, the negative electrode lead foil 112a is attached to the other surface of the substrate 121, and the other end surface of the conductor 160 comes into contact with the negative electrode lead foil 112a. Next, resistance welding is performed to join both end faces of the conductor 160 to the positive electrode lead foil 111a and the negative electrode lead foil 112a, thereby connecting the positive electrode lead foil 111a and the negative electrode lead foil 112a via the conductor 160.

[0047] In this way, a biplate 120 (a biplate with positive and negative lead foils) is obtained in which positive lead foil 111a and negative lead foil 112a are fixed to both sides of substrate 121. The required number of biplates with positive and negative lead foils are prepared.

[0048] <Process for manufacturing end plates with lead foil for the positive electrode> The substrate 131 of the first end plate 130 is placed on a workbench with the recess 131b facing up, adhesive is applied to the recess 131b, and the positive electrode lead foil 111aa is inserted into the recess 131b. At this time, the post portions 133 of the end plate 130 are passed through the insertion holes 111c of the positive electrode lead foil 111aa. The adhesive is cured to form an adhesive layer 150. This results in a first end plate 130 (an end plate with a positive electrode lead foil) in which the positive electrode lead foil 111aa is fixed to one surface of the substrate 131.

[0049] <Process for manufacturing end plates with lead foil for negative electrodes> The substrate 141 of the second end plate 140 is placed on a workbench with the recess 141b facing up, adhesive is applied to the recess 141b, and the negative electrode lead foil 112aa is inserted into the recess 141b. At this time, the column portions 143 of the second end plate 140 are passed through the insertion holes 112c of the negative electrode lead foil 112aa. The adhesive is cured to form an adhesive layer 150. This results in a second end plate 140 (an end plate with a negative electrode lead foil) in which the negative electrode lead foil 112aa is fixed to one surface of the substrate 141.

[0050] <The process of stacking and joining plates> First, the first end plate 130 to which the positive electrode lead foil 111a is fixed is placed on a workbench with the positive electrode lead foil 111a facing upward, and the positive electrode active material layer 111b is placed on the positive electrode lead foil 111a. At this time, the column portions 133 of the first end plate 130 are passed through the insertion holes 111d of the positive electrode active material layer 111b. Next, the separator 113 and the negative electrode active material layer 112b are placed in this order on the positive electrode active material layer 111b.

[0051] Next, the biplate 120 with the positive and negative electrode lead foils is placed with the negative electrode lead foil 112a side facing downward on the first end plate 130 in this state. At this time, the column parts 123 of the biplate 120 are passed through the insertion holes 113c of the separator 113 and the insertion holes 112d of the negative electrode active material layer 112b, and placed on the column parts 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.

[0052] 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 lead foil 111a is exposed on the upper surface of the biplate 120.

[0053] Next, the positive electrode active material layer 111b, separator 113, 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 lead foils is placed on top of it, with the negative electrode lead foil 112a side facing downwards. In this state, the combined body is fixed, and vibration welding is performed while vibrating the biplate 120 with the lead foils for the positive and negative electrodes 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.

[0054] Finally, the positive electrode active material layer 111b, the separator 113, 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 lead foil 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.

[0055] 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.

[0056] <Other processes> The main body 101 assembled as described above is placed with the surface on which the liquid inlet 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 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.

[0057] Next, in the state shown in FIG. 1, the electrolyte is supplied from each of the electrolyte supply ports 191 of the lid 190. Finally, the bipolar lead-acid battery 100 is obtained by forming the battery under predetermined conditions.

[0058] [Action, effect] As described above, in the bipolar lead-acid battery 100 of this embodiment, the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 constituting the biplate 120 with positive and negative electrode lead foils are formed of the same lead alloy. That is, the lead alloys constituting the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 have the same melting point. This reduces the defect rate during resistance welding to join both end surfaces of the conductor 160 to the positive electrode lead foil 111a and the negative electrode lead foil 112a. As a result, the productivity of the biplate 120 with positive and negative electrode lead foils is improved. In other words, it is possible to efficiently manufacture a biplate 120 with positive and negative electrode lead foils that has excellent durability.

[0059] On the other hand, if the lead alloys forming the positive lead foil 111a, the negative lead foil 112a, and the conductor 160 have different compositions, the resistance welding of lead alloys with different melting points becomes difficult, making it more likely that poor welding will occur. Furthermore, the presence of poor welding will result in insufficient durability of the biplate with positive and negative lead foils.

[0060] Furthermore, because the thickness of the positive electrode lead foil (positive electrode current collector) 111a and the thickness of the negative electrode lead foil (negative electrode current collector) 112a are the same, the heat capacity of the region where the positive electrode lead foil 111a and the conductor 160 are welded is the same as the heat capacity of the region where the negative electrode lead foil 112a and the conductor 160 are welded. Therefore, the timing of melting of the lead alloy during welding is synchronized at the interface between the positive electrode lead foil 111a and the conductor 160 and the interface between the negative electrode lead foil 112a and the conductor 160. As a result, the defect rate during resistance welding of the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 is reduced.

[0061] Furthermore, if any of the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 has a granular structure, the pressure applied to the weld by the electrode tip during resistance welding may cause the weld to become more recessed than necessary. As a result, the contact area between the electrode tip and the weld increases and the distance between the electrode tips decreases, reducing resistance and potentially resulting in insufficient resistance heat and poor welding. In contrast, in this embodiment, the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 all have a rolled structure that is harder than a granular structure, resulting in a lower defect rate during resistance welding than if any of them had a granular structure.

[0062] 〔others〕 In the bipolar lead-acid battery 100 of the embodiment, the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 that constitute the biplate 120 with positive and negative electrode lead foils are formed of a lead alloy having the same composition, but the positive electrode lead foil 111a and the conductor 160 may be formed of a lead alloy having the same composition, and the negative electrode lead foil 112a may be formed of a lead alloy having a different composition.

[0063] In the bipolar lead-acid battery 100 of the embodiment, the positive electrode lead foil 111a, the negative electrode lead foil 112a that constitute the biplate 120 with positive and negative electrode lead foils, and the lead alloy that forms the conductor 160 have a composition in which the calcium (Ca) content is 0.01 mass% or more and 0.1 mass% or less, the tin (Sn) content is 1.5 mass% or more and 2.0 mass% or less, and the remainder is lead and unavoidable impurities. However, even if the composition is other than this, the above-mentioned effects can be obtained as long as the composition of the lead alloy that forms the positive electrode lead foil 111a, the negative electrode lead foil 112a, and the conductor 160 is the same.

[0064] Furthermore, even if the compositions are different, as long as the components are the same, the defect rate during resistance welding can be reduced compared to when the components are different. Furthermore, "same composition" and "same components" mean that they are the same within the tolerance range. Furthermore, when the components of the lead alloy forming the positive electrode current collector and the conductor are lead (Pb), calcium (Ca), and tin (Sn), the ratio ([C2] / [C1]) of the calcium content [C2] of the lead alloy forming the conductor to the calcium content [C1] of the lead alloy forming the positive electrode current collector is preferably 10.0 or less, more preferably 7.0 or less, and even more preferably 5.0 or less.

[0065] In addition, in the embodiment, the connection between both end faces of the conductor and the positive and negative current collector plates is performed using a resistance welding method, but the above-mentioned effects can also be obtained by using a method other than resistance welding (such as ultrasonic welding) that utilizes heat. Furthermore, the hardness of the positive electrode current collector plate and the negative electrode current collector plate is preferably 10 or more and 16 or less in terms of Vickers hardness measured by a micro Vickers hardness test.

[0066] The bipolar lead-acid 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 members include a substrate covering at least one of the positive electrode side and the negative electrode side of the cell members, and a frame body surrounding the side surfaces of the cell members. The cell members and the substrates of the space-forming members are arranged in an alternate stacked state, the plurality of cell members are electrically connected in series, and the opposing surfaces of the adjacent frame bodies are joined together.

[0067] In each aspect of the biplate for a bipolar lead-acid battery of the present invention, a substrate constituting the space-forming member, excluding end plates arranged at both ends of the cell members in the stacking direction, has a through hole in the thickness direction, a conductor is arranged in the through hole, a positive current collector plate constituting one of the cell members is arranged on one side of the substrate, and a negative current collector plate constituting the other cell member is arranged on the other side of the substrate, and both end faces of the conductor are joined to the positive current collector plate and the negative current collector plate, respectively. [Explanation of symbols]

[0068] 100 Bipolar lead-acid battery 101 Main Unit 110 Cell member 111 Positive electrode 112 Negative electrode 111a Positive lead foil (positive current collector plate) 112a Lead foil for negative electrode (negative electrode current collector plate) 111b Positive electrode active material layer 112b Negative electrode active material layer 113 Separator 120 Biplate (space forming member) 121 Biplate board (main board) 121a through hole 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 190 Lid 191 Electrolyte supply port C. Space for accommodating cell components

Claims

1. a substrate disposed between adjacent cell members constituting a bipolar lead-acid battery; the substrate has a through hole in a thickness direction, and a conductor is disposed in the through hole; a positive electrode current collector that constitutes one of the cell members is disposed on one surface of the substrate, and a negative electrode current collector that constitutes the other cell member is disposed on the other surface of the substrate; both end surfaces of the conductor are joined to the positive electrode current collector plate and the negative electrode current collector plate, respectively; The positive electrode current collector and the conductor are formed of the same lead alloy.

2. a substrate disposed between adjacent cell members constituting a bipolar lead-acid battery; the substrate has a through hole in a thickness direction, and a conductor is disposed in the through hole; a positive electrode current collector that constitutes one of the cell members is disposed on one surface of the substrate, and a negative electrode current collector that constitutes the other cell member is disposed on the other surface of the substrate; both end surfaces of the conductor are joined to the positive electrode current collector plate and the negative electrode current collector plate, respectively; The positive electrode current collector, the negative electrode current collector, and the conductor are formed of the same lead alloy.

3. A substrate is disposed between adjacent cell members constituting a bipolar lead-acid battery, the substrate has a through hole in a thickness direction, and a conductor is disposed in the through hole; a positive electrode current collector that constitutes one of the cell members is disposed on one surface of the substrate, and a negative electrode current collector that constitutes the other cell member is disposed on the other surface of the substrate; both end surfaces of the conductor are joined to the positive electrode current collector plate and the negative electrode current collector plate, respectively; The positive electrode current collector and the conductor are made of the same lead alloy.

4. A substrate is disposed between adjacent cell members constituting a bipolar lead-acid battery, the substrate has a through hole in a thickness direction, and a conductor is disposed in the through hole; a positive electrode current collector that constitutes one of the cell members is disposed on one surface of the substrate, and a negative electrode current collector that constitutes the other cell member is disposed on the other surface of the substrate; both end surfaces of the conductor are joined to the positive electrode current collector plate and the negative electrode current collector plate, respectively; The positive electrode current collector, the negative electrode current collector, and the conductor are formed of a lead alloy having the same composition.

5. 5. The biplate for a bipolar lead-acid battery according to claim 4, wherein the thickness of the positive current collector and the thickness of the negative current collector are the same, and the positive current collector, the negative current collector, and the conductor all have a rolled texture.

6. 3. The biplate for a bipolar lead-acid battery according to claim 1, wherein the lead alloy comprises lead (Pb), calcium (Ca), and tin (Sn).

7. 5. The biplate for a bipolar lead-acid battery according to claim 3 or 4, wherein the lead alloy has a calcium (Ca) content of 0.01 mass% or more and 0.1 mass% or less, a tin (Sn) content of 1.5 mass% or more and 2.0 mass% or less, and the remainder being lead and unavoidable impurities.

8. 6. The biplate for a bipolar lead-acid battery according to claim 5, wherein the lead alloy has a composition in which the calcium (Ca) content is 0.01 mass% or more and 0.1 mass% or less, the tin (Sn) content is 1.5 mass% or more and 2.0 mass% or less, and the remainder is lead and unavoidable impurities.

9. A bipolar lead-acid battery comprising the biplate for a bipolar lead-acid battery according to any one of claims 1 to 5 and 8.

10. A bipolar lead-acid battery comprising the biplate for a bipolar lead-acid battery according to claim 6.

11. A bipolar lead-acid battery comprising the biplate for a bipolar lead-acid battery according to claim 7.

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