Battery module

Abstract

Provided is a battery module in which connection reliability between electrode laminates can be improved. The battery module is provided with: a monoblock housing; a plurality of electrode laminates which are housed in the monoblock housing in a vertical orientation, are arranged in parallel to each other, are in a vertically long shape, and each have a positive electrode plate, a positive electrode tab lead, a negative electrode plate, a negative electrode tab lead, and a hydroxide ion conductive separator; a plurality of terminal joints which each connect, in series via the positive electrode tab lead and / or the negative electrode tab lead, adjacent electrode laminates among the plurality of electrode laminates; and an electrolyte with which the monoblock housing is filled and in which the electrode laminates are immersed. Each of the terminal joints is composed of a pair of connection terminals connected to the adjacent electrode laminates. The pair of connection terminals are joined to each other to form a joint part. The joint part is reinforced by being covered with a resin.

Description

Battery module

[0001] The present disclosure relates to a battery module.

[0002] In order to obtain high voltage and large current, stacked batteries made by combining a plurality of single cells are widely adopted. A stacked battery has a configuration in which a stack obtained by connecting a plurality of single cells in series or parallel is housed in one battery container. For example, Patent Document 1 (WO2017 / 086278) discloses a zinc secondary battery in which a plurality of electrode cartridges each including an electrode and a separator are housed in a sealed container.

[0003] In addition, in order to further increase the capacity and output, it is also generally practiced to modularize a battery module by arranging a plurality of battery units each including a stacked battery. For example, Patent Document 2 (WO2018 / 173110) discloses a battery module in which a plurality of rectangular parallelepiped battery units are housed in a frame structure, and it is preferable that a plurality of single cells of alkaline secondary batteries (for example, nickel-zinc secondary batteries and zinc-air secondary batteries) are housed in the battery unit in the form of an assembled battery or a battery module.

[0004] By the way, in the field of sealed lead-acid batteries, as a battery case, a battery tank having a monoblock structure produced by integrally molding resin or the like and having a plurality of cell chambers partitioned by partition walls is used. For example, Patent Document 3 (Japanese Patent No. 3807206) discloses a sealed lead-acid battery in which cells each having a positive electrode, a negative electrode, and a separator are housed in each cell chamber of a monoblock battery tank partitioned into 19 or more cell chambers.

[0005] WO2017 / 086278 WO2018 / 173110 Japanese Patent No. 3807206 WO2013 / 118561 WO2016 / 076047 WO2016 / 067884 WO2019 / 069762 WO2020 / 255856

[0006] In modularized zinc secondary batteries, applying a monoblock housing structure would be advantageous in terms of reducing the number of parts and lightening the module. On the other hand, in such a monoblock zinc secondary battery module, it is conceivable to connect multiple individual cells in series by joining the terminals connected to each individual cell to form a terminal joint. However, when using such a terminal joint, concerns may arise regarding the reliability of the connections between individual cells from the perspective of joint quality, etc.

[0007] The present inventors have now discovered that the reliability of connections between electrode stacks can be improved by housing multiple electrode stacks as single cell elements within a single monoblock housing, connecting adjacent electrode stacks in series using terminal connectors, and covering the joints of the terminal connectors with resin.

[0008] Therefore, an object of the present invention is to provide a battery module capable of improving the connection reliability between electrode stacks.

[0009] The following aspects are provided according to this disclosure. [Aspect 1] A monoblock housing, a plurality of vertically elongated electrode stacks housed vertically within the monoblock housing and arranged parallel to each other, wherein each of the electrode stacks includes: a positive electrode plate including a positive electrode active material layer and a positive electrode current collector, a positive electrode tab lead extending from the end of the positive electrode plate, a negative electrode plate provided opposite the positive electrode plate and including a negative electrode active material layer and a negative electrode current collector, a negative electrode tab lead extending from the end of the negative electrode plate at a position not overlapping with the positive electrode tab lead, and a hydroxide ion conductive separator that isolates the positive electrode plate and the negative electrode plate in a manner that allows hydroxide ion conduction, a plurality of terminal connectors that connect adjacent electrode stacks in the plurality of electrode stacks in series via the positive electrode tab lead and / or the negative electrode tab lead, and an electrolyte filled within the monoblock housing into which the electrode stacks are immersed. A battery module in which each of the terminal joints is composed of a pair of connection terminals connected to adjacent electrode stacks, the pair of connection terminals are joined to each other to form a joint, and the joint is covered and reinforced with resin. [Aspect 2] The battery module according to aspect 1, wherein each of the connection terminals is L-shaped. [Aspect 3] The battery module according to aspect 1 or 2, wherein each of the connection terminals has a vertical portion that is joined to the positive electrode tab lead or the negative electrode tab lead and extends upward, and a horizontal portion that extends horizontally from the upper end of the vertical portion, and the joint is formed in the horizontal portion. [Aspect 4] The battery module according to any one of aspects 1 to 3, wherein the joint is embedded in the resin. [Aspect 5] The battery module according to any one of aspects 1 to 4, wherein the resin includes epoxy resin and / or olefin resin. [Aspect 6] The battery module according to any one of aspects 1 to 5, wherein the connection terminals are made of copper. [Aspect 7] The battery module according to any one of aspects 1 to 6, wherein the pair of connection terminals are welded to each other at the joint.[Aspect 8] The battery module according to any one of aspects 1 to 7, wherein the monoblock housing has a bottom, a pair of longitudinal side walls parallel to the stacking direction of the electrode stack, a pair of transverse side walls perpendicular to the stacking direction of the electrode stack, and a lid, and the plurality of electrode stacks are housed in an exposed state within one monoblock housing without each being housed in an individual single cell case.

[0010] This is a perspective view showing an example of a battery module of the present invention. This is a schematic cross-sectional view of the battery module shown in Figure 1. This is a perspective view showing an example of a plurality of electrode stacks connected in series in the battery module shown in Figure 1. This is a perspective view schematically showing an example of a procedure for joining a pair of connection terminals to form a terminal assembly. This is a perspective view schematically showing an example of a procedure for embedding the joint portion of a terminal assembly with resin. This is a schematic diagram showing a cross-section of the joint portion of a resin-embedded terminal assembly shown in Figure 5. This is a perspective view schematically showing the specific configuration of the electrode stack shown in Figure 3. This is a schematic cross-sectional view schematically showing the specific configuration of the electrode stack shown in Figure 3. This is a perspective view showing an example of a positive electrode plate or a negative electrode plate in the electrode stack shown in Figure 3. This is a perspective view showing a positive electrode plate or a negative electrode plate shown in Figure 9 covered with a hydroxide ion conductive separator or a liquid-retaining member.

[0011] Figures 1 to 3 show one embodiment of the battery module of the present invention. The battery module 10 shown in Figures 1 to 3 comprises a monoblock housing 12, a plurality of electrode stacks 14, a plurality of terminal connectors 30, and an electrolyte 36. The plurality of electrode stacks 14 are housed vertically within the monoblock housing 12 and are arranged parallel to each other. The electrode stacks 14 have an elongated shape, that is, when the electrode stack is viewed in cross-section, the length in the height direction (height H shown in Figure 3) is longer than the length in the thickness direction (thickness T shown in Figure 3). As shown in Figures 7 to 10, each of the electrode stacks 14 includes a positive electrode plate 16, a positive electrode tab lead 18, a negative electrode plate 20, a negative electrode tab lead 22, and a hydroxide ion conductive separator 24. Details of each element constituting the electrode stack 14 will be described later. The electrolyte 36 is filled into the monoblock housing 12 and the electrode stacks 14 are immersed in it. The terminal connector 30 connects adjacent electrode stacks in a plurality of electrode stacks 14 in series via a positive electrode tab lead 18 and / or a negative electrode tab lead 22. As shown in Figures 2 and 4, each terminal connector 30 consists of a pair of connection terminals 30a connected to an adjacent electrode stack 14. The pair of connection terminals 30a are joined together to form a joint portion 30b. The joint portion 30b is then covered and reinforced with resin 32. In this way, by housing a plurality of electrode stacks 14 as single cell elements within a single monoblock housing 12, connecting adjacent electrode stacks 14 in series with terminal connectors 30, and covering the joint portion 30b of the terminal connector with resin 32, the reliability of the connections between the electrode stacks 14 can be improved.

[0012] As mentioned above, if a monoblock structure housing can be applied to a zinc secondary battery that has been made into a battery module, it will be advantageous in terms of reducing the number of parts and making the module lighter. On the other hand, in such a monoblock structure zinc secondary battery module, it is conceivable to connect multiple single cells in series by joining (for example, welding) the terminals connected to each of the single cells (including the form of a battery pack in which multiple single cells are combined). However, when such a terminal joint is used, concerns may arise regarding the reliability of the connection between the single cells in terms of joint quality, etc. In particular, when copper terminals, which are suitable as connection terminals for zinc secondary batteries, are used, welding and the like become difficult, making it difficult to join the terminals with high precision. Also, when the battery module is used for a long period of time, there is a risk that the joint may break. In this regard, according to the battery module 10 of the present invention, the joint portion 30b of the terminal joint is reinforced by being covered with resin 32, so that the joint between a pair of connection terminals 30a can be made stronger, and as a result the reliability of the connection between the electrode stacks 14 can be improved. Furthermore, since the battery module 10 has a simple configuration in which each of the multiple electrode stacks 14 is housed in an exposed state within a single monoblock housing 12, rather than being housed in an individual single cell case, the number of parts can be reduced and the weight can be reduced.

[0013] Furthermore, the above-mentioned problem concerning the joint can be said to be a problem unique to zinc secondary batteries that could not occur in a sealed lead-acid battery with a monoblock structure as disclosed in Patent Document 3. In other words, in lead-acid batteries, it is common to connect electrode plates using terminals made of lead alloy, and such connections using lead alloy terminals can be made without going through joining processes such as welding. For example, in lead-acid batteries, a cast-on-strap method can be used, in which multiple electrode plates to be connected are inserted into molten lead alloy with their tips in an inverted state, and the lead alloy is solidified to connect the electrode plates.

[0014] The terminal joint 30 is preferably joined (e.g., by welding) to the positive electrode tab lead 18 and / or the negative electrode tab lead 22 to connect adjacent electrode stacks 14 in a plurality of electrode stacks 14 in series. Each terminal joint 30 consists of a pair of connection terminals 30a connected to an adjacent electrode stack 14. As shown in Figure 2, each of the connection terminals 30a preferably has an L-shape. Figure 4 shows a preferred embodiment of the connection terminals 30a and a preferred example of a joining method. As shown in the upper part of Figure 4, each of the connection terminals 30a preferably has a vertical portion 30aa that is joined to the positive electrode tab lead 18 or the negative electrode tab lead 22 and extends upward, and a horizontal portion 30ab that extends horizontally from the upper end of the vertical portion 30aa. In this case, it is preferable that the joining portion 30b is formed in the horizontal portion 30ab of the connection terminal. For example, as shown in the lower part of Figure 4, the joint portion 30b can preferably be formed by overlapping the upper surface of one connection terminal 30a with the lower surface of the other connection terminal 30a and welding them together. Therefore, it is preferable that the terminal joint 30 has a pair of connection terminals 30a welded to each other at the joint portion 30b. Preferred methods for joining a pair of connection terminals 30a include ultrasonic welding (ultrasonic bonding), laser welding, TIG welding, resistance welding, and the like.

[0015] The connection terminal 30a may be made of a known metal or alloy used as a connection terminal for a zinc secondary battery, but is preferably made of copper from the viewpoint of high conductivity. Pure copper is preferred for the copper that makes up the connection terminal 30a. As mentioned above, when copper connection terminals 30a are used, welding the terminals together becomes difficult, making it difficult to join the terminals together with high precision. However, in the present invention, the joint portion 30b is covered with resin 32, which makes it possible to firmly join a pair of connection terminals 30a together.

[0016] From the viewpoint of effectively reinforcing the joint 30b, it is preferable that the resin 32 includes an epoxy resin and / or an olefin resin. In particular, from the viewpoint of more effectively reinforcing the joint 30b, it is preferable that the joint 30b of the terminal joint is embedded in the resin 32. Figures 5 and 6 show an example of a preferred method for embedding the joint 30b of the terminal joint with the resin 32. First, as shown in the upper part of Figure 5, the resin 32 is filled into the area on the back surface of the lid 12d of the monoblock housing where the terminal joint 30 is housed. Next, as shown in the upper and lower parts of Figure 5, with a group of electrode stacks 14 connected in series by the terminal joint 30 inverted, the terminal joint 30 is inserted into the resin 32 filled in the lid 12d, and the resin 32 is cured. In this way, as shown in Figure 6, the joint of the terminal joint 30 (for example, the joint formed in the horizontal part 30ab) can be preferably embedded by the resin 32. In this case, the upper surface of the horizontal portion 30ab of the terminal joint (the surface away from the electrode stack 14) may be in contact with the inner surface of the cover portion 12d, or it may be spaced apart from the inner surface of the cover portion 12d. Therefore, the horizontal portion 30ab of the terminal joint may be covered with resin 32 from its lower surface (the surface closer to the electrode stack 14) to its upper surface. In other words, the resin 32 may wrap around to the upper surface of the terminal joint 30 to cover the joint portion 30b, thereby reinforcing the joint portion 30b more effectively.

[0017] As shown in Figures 1 and 2, the monoblock housing 12 typically has a bottom portion 12a, a pair of longitudinal side walls 12b parallel to the stacking direction of the electrode stack 14, a pair of short side walls 12c perpendicular to the stacking direction of the electrode stack 14, and a lid portion 12d. In particular, it is preferable that the bottom portion 12a, the longitudinal side walls 12b, and the short side walls 12c form a single block structure as the main body that houses the electrode stack 14 and the electrolyte 36. That is, it is preferable that the main body is not assembled from multiple parts, but is a single molded product formed by a method such as injection molding.

[0018] As shown in Figure 1, it is preferable that ribs 12e are provided on the outer surface of each short side wall portion 12c to reinforce the monoblock housing 12 and improve its strength. This makes it possible to effectively suppress the expansion of the electrode stack 14 when it expands during the charge-discharge reaction. That is, when the electrode stack 14 expands, the short side wall portion 12c side of the monoblock housing corresponding to the main surface of the electrode stack 14 is pressed. In this respect, the monoblock housing 12 is reinforced by the ribs 12e provided on the outer surface of each short side wall portion 12c, which prevents deformation of the housing. As a result, expansion can be suppressed by the pressure applied to the electrode stack 14 by the monoblock housing 12 without the use of additional restraint parts. The size of the monoblock housing 12 can be determined according to the dimensions and number of electrode stacks 14 to be housed. For example, as shown in Figure 2, it is preferable to adjust the length of the longitudinal side wall portion 12b so that the electrode stacks 14 installed at both ends of the group of electrode stacks 14 can come into contact with the inner surface of the short side wall portion 12c, thereby pressurizing the electrode stack 14 and effectively suppressing its expansion.

[0019] It is preferable that the rib 12e is integrally molded together with the bottom portion 12a, the longitudinal side wall portion 12b, and the short side wall portion 12c. From the viewpoint of improving the yield during the molding of the monoblock housing 12 (for example, during injection molding), it is preferable that the rib 12e is provided on the outer surface of the short side wall portion 12c so as to form a repeating pattern of squares or hexagons when viewed from above, and more preferably so as to form a repeating pattern of hexagons. In particular, it is preferable that the rib 12e is provided on the short side wall portion 12c so as to form a honeycomb pattern. Having such a three-dimensional structure for the rib 12e makes it possible to further improve the strength of the housing while reducing its weight, and as a result, the expansion of the electrode laminate 14 can be suppressed more effectively.

[0020] The height of the rib 12e is preferably 5 to 15 mm, more preferably 6 to 14 mm, and even more preferably 8 to 12 mm. The thickness of the rib 12e is preferably 2 to 10 mm, more preferably 3 to 9 mm, and even more preferably 4 to 8 mm. Furthermore, in each of the short side walls 12c, the ratio of the planar area occupied by the rib 12e to the planar area of ​​the short side wall 12c is preferably 10 to 40%, more preferably 15 to 40%, and even more preferably 20 to 40%. By controlling the shape of the rib 12e to fall within these ranges, it is possible to achieve a better balance between weight reduction and strength improvement of the monoblock housing 12.

[0021] As shown in Figure 2, the monoblock housing 12 typically has a plurality of partition walls 12f, and these partition walls 12f typically divide the internal space in which the electrode stacks 14 and electrolyte 36 are housed into a plurality of compartments in which the plurality of electrode stacks 14 can be housed spaced apart from each other. Preferably, the partition walls 12f are integrally molded together with the bottom portion 12a, the longitudinal side wall portion 12b, and the short side wall portion 12c. The number of partition walls 12f can be determined according to the number of electrode stacks 14 to be housed. The thickness of each partition wall 12f is not particularly limited, but is preferably 2 to 8 mm, more preferably 2 to 5 mm, from the viewpoint of preventing deformation due to expansion of the electrode stacks 14 and effectively applying pressure, as well as from the viewpoint of integral moldability.

[0022] The monoblock housing 12 is preferably made of an alkali-resistant material, and is particularly preferably made of an alkali-resistant resin from the viewpoint of integral moldability and weight reduction. Examples of resins that make up the monoblock housing 12 include polypropylene resin, polyolefin resin, ABS resin, and modified polyphenylene ether. The monoblock housing 12 (for example, the lid portion 12d) may also have a pressure relief valve for releasing gas inside the housing at a predetermined operating pressure or higher. The operating pressure of the pressure relief valve is preferably 50 kPa or less, which effectively prevents damage to the housing (especially a resin housing).

[0023] The configuration of the electrode stack 14 will be described below with reference to Figures 7 to 10. The electrode stack 14 shown in Figures 7 to 10 includes a positive electrode plate 16, a positive electrode tab lead 18, a negative electrode plate 20, a negative electrode tab lead 22, and a hydroxide ion conductive separator 24. The positive electrode plate 16 includes a positive electrode active material layer 16a and a positive electrode current collector 16b. The positive electrode tab lead 18 extends from the end of the positive electrode plate 16. The negative electrode plate 20 is provided opposite the positive electrode plate 16 and includes a negative electrode active material layer 20a and a negative electrode current collector 20b. The negative electrode active material layer 20a includes at least one selected from the group consisting of zinc, zinc oxide, zinc alloy, and zinc compounds. The negative electrode tab lead 22 extends from the end of the negative electrode plate 20 at a position that does not overlap with the positive electrode tab lead 18. The hydroxide ion conductive separator 24 isolates the positive electrode plate 16 and the negative electrode plate 20 in a manner that allows hydroxide ions to conduct. Typically, the positive electrode plate 16, the negative electrode plate 20, and the hydroxide ion conductive separator 24 are each quadrilateral in shape (typically square). The number of electrode stacks 14 housed in the monoblock housing 12 is not particularly limited, but is preferably six or more, and more preferably six to eight. As shown in Figure 3, typically, electrode post terminals 34 for electrical connection to an external circuit are provided at both ends of an electrode stack 14 in a group of electrode stacks 14.

[0024] The electrode stack 14 is a stack containing multiple electrode layers. That is, as shown in Figures 7 and 8, the electrode stack 14 preferably has the configuration of a positive-negative electrode stack in which units of positive electrode 16 / hydroxide ion conductive separator 24 / negative electrode 20 are repeated, comprising multiple positive electrode plates 16, multiple negative electrode plates 20, and multiple hydroxide ion conductive separators 24. In other words, the electrode stack 14 preferably contains multiple unit cells 14a, each having a pair of positive electrode plates 16 and negative electrode plates 20 together with a hydroxide ion conductive separator 24, thereby forming a multilayer cell as a whole. This is the configuration of a so-called battery pack or stacked battery, which is advantageous in that high voltage and high current can be obtained. The electrode stack 14 preferably has the configuration of a nickel-zinc secondary battery, a silver-zinc secondary battery, a manganese-zinc secondary battery, or various other types of alkali-zinc secondary batteries.

[0025] The positive electrode plate 16 includes a positive electrode active material layer 16a. The positive electrode active material constituting the positive electrode active material layer 16a is not particularly limited and can be appropriately selected from known positive electrode materials depending on the type of zinc secondary battery. For example, in the case of a nickel-zinc secondary battery, a positive electrode containing nickel hydroxide and / or nickel oxyhydroxide may be used. In this case, the positive electrode active material layer 16a may also contain an additive which is at least one selected from the group consisting of silver compounds, manganese compounds, and titanium compounds, thereby promoting a positive electrode reaction that absorbs hydrogen gas generated by the self-discharge reaction. Furthermore, the positive electrode active material layer 16a may further contain cobalt. It is preferable that the cobalt is included in the positive electrode plate 16 in the form of cobalt oxyhydroxide. In the positive electrode active material layer 16a, cobalt functions as a conductive additive, thereby contributing to an improvement in charge-discharge capacity. Alternatively, in the case of an air-zinc secondary battery, an air electrode may be used as the positive electrode.

[0026] The positive electrode plate 16 further includes a positive electrode current collector 16b. A preferred example of the positive electrode current collector 16b is a porous nickel substrate such as a foamed nickel plate. In this case, for example, a positive electrode plate consisting of a positive electrode and a positive electrode current collector can be preferably manufactured by uniformly applying a paste containing an electrode active material such as nickel hydroxide onto the porous nickel substrate and drying it. At that time, it is also preferable to press the positive electrode plate (i.e., positive electrode / positive electrode current collector) after drying to prevent the electrode active material from falling off and to improve the electrode density. If the positive electrode current collector 16b is a porous nickel substrate such as a foamed nickel plate, the uncoated area of ​​the positive electrode current collector 16b may be processed into a tab shape by pressing it.

[0027] As shown in Figure 9, the positive electrode plate 16 may have an uncoated region U along its upper end where the positive electrode active material layer 16a is absent. In such a case, it is preferable that the positive electrode tab lead 18 is welded to the positive electrode current collector 16b in the uncoated region U, and that the insulating tape 26 is attached to the uncoated region U so that the welded portion W is covered with insulating tape 26. This makes it difficult for the tip of the positive electrode tab lead 18 to penetrate the hydroxide ion conductive separator 24 or the liquid retention member 28, and even if it does penetrate them and come into contact with the positive electrode plate 16, the insulating tape 26 functions as an insulating material, making a short circuit less likely.

[0028] The positive electrode tab lead 18 is preferably provided so as to extend upward from the end of the positive electrode plate 16. The positive electrode tab lead 18 is not particularly limited and can be made of commercially available thin metal. As shown in Figure 8, it is preferable that a plurality of positive electrode tab leads 18 are joined to a single connection terminal 30a or a member electrically connected thereto to form a positive electrode tab joint 19. This allows for current collection with a simple configuration and space efficiency, and also facilitates connection to the connection terminal 30a. The joining of the positive electrode tab lead 18 to the positive electrode current collector 16b, connection terminal 30a, and other members can be performed using known joining methods such as ultrasonic welding (ultrasonic bonding), laser welding, TIG welding, or resistance welding.

[0029] The negative electrode plate 20 includes a negative electrode active material layer 20a. The negative electrode active material constituting the negative electrode active material layer 20a includes at least one selected from the group consisting of zinc, zinc oxide, zinc alloys, and zinc compounds. Zinc may be included in any form of zinc metal, zinc compounds, or zinc alloys, as long as it has electrochemical activity suitable for a negative electrode. Preferred examples of negative electrode materials include zinc oxide, zinc metal, calcium zincate, etc., but a mixture of zinc metal and zinc oxide is more preferred. The negative electrode active material may be configured in a gel state, or it may be mixed with an electrolyte to form a negative electrode composite material. For example, a gelled negative electrode can be easily obtained by adding an electrolyte and a thickener to the negative electrode active material. Examples of thickeners include polyvinyl alcohol, polyacrylate, CMC, alginic acid, etc., but polyacrylic acid is preferred because it has excellent chemical resistance to strong alkalis.

[0030] As the zinc alloy, a mercury- and lead-free zinc alloy known as a mercury-free zinc alloy can be used. For example, a zinc alloy containing 0.01 to 0.1 mass% indium, 0.005 to 0.02 mass% bismuth, and 0.0035 to 0.015 mass% aluminum is preferred because it has a hydrogen gas generation suppression effect. In particular, indium and bismuth are advantageous in that they improve discharge performance. Using a zinc alloy as the negative electrode can improve safety by suppressing hydrogen gas generation through slowing the self-dissolution rate in an alkaline electrolyte.

[0031] The shape of the negative electrode material is not particularly limited, but it is preferably in powder form, as this increases the surface area and allows it to handle high-current discharge. The preferred average particle size of the negative electrode material is in the range of 3 to 100 μm in the short diameter for zinc alloys. Within this range, the surface area is large, making it suitable for handling high-current discharge, and it is also easy to uniformly mix with the electrolyte and gelling agent, resulting in good handling during battery assembly.

[0032] The negative electrode plate 20 further includes a negative electrode current collector 20b. The negative electrode active material layer 20a may be arranged on both sides of the negative electrode current collector 20b, or the negative electrode active material layer 20a may be arranged on only one side of the negative electrode current collector 20b. From the viewpoint of fixing the negative electrode active material to the current collector, it is preferable to use a metal plate having multiple (or many) openings for the negative electrode current collector 20b. Preferred examples of such a negative electrode current collector 20b include expanded metal, perforated metal, metal mesh, and combinations thereof, more preferably copper expanded metal, copper perforated metal, and combinations thereof, and particularly preferably copper expanded metal. In this case, for example, a negative electrode plate consisting of a negative electrode / negative electrode current collector can be preferably manufactured by coating a mixture containing zinc oxide powder and / or zinc powder, and optionally a binder (e.g., polytetrafluoroethylene particles), onto copper expanded metal. In this process, it is also preferable to press the dried negative electrode plate (i.e., negative electrode / negative electrode current collector) to prevent the electrode active material from falling off and to improve electrode density. Expanded metal is a mesh-like metal sheet made by expanding a metal sheet using an expansion machine, which cuts the sheet in a staggered pattern, and then shaping the cuts into a diamond or tortoise shell pattern. Perforated metal, also known as perforated metal, is a metal sheet with holes punched into it. Metal mesh is a metal product with a wire mesh structure and is different from expanded metal and perforated metal.

[0033] As shown in Figure 9, the negative electrode plate 20 may have an uncoated region U along its upper end where the negative electrode active material layer 20a is absent. In such a case, it is preferable that the negative electrode tab lead 22 is welded to the negative electrode current collector 20b in the uncoated region U, and that the insulating tape 26 is attached to the uncoated region U so that the welded portion W is covered with insulating tape 26. This makes it difficult for the tip of the negative electrode tab lead 22 to penetrate the hydroxide ion conductive separator 24 or the liquid retention member 28, and even if it does penetrate them and come into contact with the negative electrode plate 20, the insulating tape 26 functions as an insulating material, making a short circuit less likely.

[0034] The negative electrode tab lead 22 is preferably provided so as to extend upward from the end of the negative electrode plate 20 at a position that does not overlap with the positive electrode tab lead 18 (see Figure 7). The negative electrode tab lead 22 is not particularly limited and can be made of commercially available thin metal. As shown in Figure 8, it is preferable that multiple negative electrode tab leads 22 are joined to a single connection terminal 30a or a member electrically connected thereto to form a negative electrode tab joint 23. This allows for current collection with a simple configuration and space efficiency, and also facilitates connection to the connection terminal 30a. The joining of the negative electrode tab lead 22 to the negative electrode current collector 20b, connection terminal 30a, and other members can be performed using known joining methods such as ultrasonic welding (ultrasonic bonding), laser welding, TIG welding, or resistance welding.

[0035] The hydroxide ion conductive separator 24 is provided to isolate the positive electrode plate 16 and the negative electrode plate 20 in a manner that allows hydroxide ions to conduct. For example, as shown in Figure 10, the positive electrode plate 16 and / or the negative electrode plate 20 (preferably the negative electrode plate 20) may be covered or enclosed by the hydroxide ion conductive separator 24. This eliminates the need for complicated sealing and bonding between the hydroxide ion conductive separator 24 and the housing, making it possible to manufacture zinc secondary batteries and their stacked batteries that can prevent zinc dendrite extension very simply and with high productivity. However, a simpler configuration in which the hydroxide ion conductive separator 24 is arranged on one side of the positive electrode plate 16 or the negative electrode plate 20 is also acceptable.

[0036] The hydroxide ion conductive separator 24 is not particularly limited as long as it is a separator capable of separating the positive electrode plate 16 and the negative electrode plate 20 in a manner that allows hydroxide ions to conduct, but typically it is a separator that contains a hydroxide ion conductive solid electrolyte and selectively passes hydroxide ions by exclusively utilizing its hydroxide ion conductivity. A preferred hydroxide ion conductive solid electrolyte is a layered double hydroxide (LDH) and / or an LDH-like compound. Therefore, it is preferable that the hydroxide ion conductive separator 24 is an LDH separator. In this specification, "LDH separator" is defined as a separator containing LDH and / or an LDH-like compound that selectively passes hydroxide ions by exclusively utilizing the hydroxide ion conductivity of the LDH and / or LDH-like compound. In this specification, "LDH-like compound" is a hydroxide and / or oxide with a layered crystalline structure similar to LDH, which may not be called LDH, and can be considered an equivalent of LDH. However, in a broader sense, "LDH" can also be interpreted as encompassing not only LDH but also LDH-like compounds. The LDH separator is preferably compounded with a porous substrate. Therefore, the LDH separator is preferably compounded with the porous substrate in a form in which LDH and / or LDH-like compounds fill the pores of the porous substrate. That is, in a preferred LDH separator, the LDH and / or LDH-like compounds block the pores of the porous substrate so as to exhibit hydroxide ion conductivity and gas impermeability (and thus function as an LDH separator exhibiting hydroxide ion conductivity). The porous substrate is preferably made of a polymer material, and it is particularly preferable that the LDH is incorporated throughout the entire thickness direction of the polymer material porous substrate. For example, known LDH separators such as those disclosed in Patent Documents 4 to 8 can be used. The thickness of the LDH separator is preferably 5 to 100 μm, more preferably 5 to 80 μm, even more preferably 5 to 60 μm, and particularly preferably 5 to 40 μm.

[0037] It is preferable that not only a hydroxide ion conductive separator 24 but also a liquid-retaining member 28 is interposed between the positive electrode plate 16 and the negative electrode plate 20. Furthermore, as shown in Figure 10, it is preferable that the positive electrode plate 16 and / or the negative electrode plate 20 are covered or wrapped by the liquid-retaining member 28. However, a simpler configuration in which the liquid-retaining member 28 is placed on one side of the positive electrode plate 16 or the negative electrode plate 20 is also acceptable. In any case, by interposing the liquid-retaining member 28, the electrolyte can be evenly distributed between the positive electrode plate 16 and / or the negative electrode plate 20 and the hydroxide ion conductive separator 24, and the exchange of hydroxide ions between the positive electrode plate 16 and / or the negative electrode plate 20 and the hydroxide ion conductive separator 24 can be efficiently carried out. The liquid-retaining member 28 is not particularly limited as long as it is a member capable of holding electrolyte, but it is preferable that it is a sheet-like member. Preferred examples of the liquid-retaining member 28 include nonwoven fabric, superabsorbent resin, liquid-retaining resin, porous sheet, and various spacers, but nonwoven fabric is particularly preferred because it allows for the production of a low-cost, high-performance negative electrode structure. The liquid-retaining member 28 or nonwoven fabric preferably has a thickness of 10 to 200 μm, more preferably 20 to 200 μm, even more preferably 20 to 150 μm, particularly preferably 20 to 100 μm, and most preferably 20 to 60 μm. With a thickness within the above range, a sufficient amount of electrolyte can be retained within the liquid-retaining member 28 while keeping the overall size of the positive electrode structure and / or negative electrode structure compact and without waste.

[0038] When the positive electrode plate 16 and / or the negative electrode plate 20 are covered or enclosed by a liquid-retaining member 28 and / or a hydroxide ion conductive separator 24, it is preferable that their outer edges (except for the edges from which the positive electrode tab lead 18 and the negative electrode tab lead 22 extend) are closed. In this case, it is preferable that the closed edges of the outer edges of the liquid-retaining member 28 and / or the hydroxide ion conductive separator 24 are achieved by bending the liquid-retaining member 28 and / or the hydroxide ion conductive separator 24, or by sealing the liquid-retaining members 28 with each other and / or the hydroxide ion conductive separators 24 with each other. Preferred sealing methods include adhesives, heat welding, ultrasonic welding, adhesive tapes, sealing tapes, and combinations thereof. In particular, LDH separators containing a porous substrate made of polymer material have the advantage of being flexible and therefore easy to bend, so it is preferable to form the LDH separator in a long shape and bend it to form a closed state on one side of the outer edge. Heat welding and ultrasonic welding can be performed using commercially available heat sealers, but in the case of sealing LDH separators together, it is preferable to perform heat welding and ultrasonic welding by sandwiching the outer periphery of the liquid-retaining member 28 between the LDH separators that constitute the outer periphery, as this allows for more effective sealing. On the other hand, commercially available adhesives, adhesive tapes, and sealing tapes can be used, but it is preferable to use those containing alkali-resistant resins to prevent deterioration in alkaline electrolytes. From this viewpoint, examples of preferred adhesives include epoxy resin adhesives, natural resin adhesives, modified olefin resin adhesives, and modified silicone resin adhesives, among which epoxy resin adhesives are more preferred due to their particularly excellent alkali resistance. An example of an epoxy resin adhesive product is the epoxy adhesive Hysol (registered trademark) (manufactured by Henkel).

[0039] The electrolyte 36 preferably contains an aqueous alkali metal hydroxide solution. Examples of alkali metal hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide, and ammonium hydroxide, but potassium hydroxide is more preferred. To suppress the self-dissolution of zinc and / or zinc oxide, zinc compounds such as zinc oxide and zinc hydroxide may be added to the electrolyte. The electrolyte 36 may be mixed with the positive electrode active material and / or negative electrode active material to exist in the form of a positive electrode composite and / or negative electrode composite. Furthermore, the electrolyte 36 may be gelled to prevent leakage of the electrolyte 36. As a gelling agent, it is desirable to use a polymer that absorbs the solvent of the electrolyte 36 and swells, and polymers such as polyethylene oxide, polyvinyl alcohol, polyacrylamide, and starch can be used.

[0040] As shown in Figure 2, it is preferable that the entire electrode stack 14 is immersed in the electrolyte 36. For example, the length L from the lower end to the upper end of the negative electrode plate 20. １ The length L from the lower end of the negative electrode plate 20 to the liquid surface of the electrolyte 36. ２ The percentage of (= (L ２ / L １ The immersion rate, expressed as (x 100), is preferably 104% or more, more preferably 107% or more, and even more preferably 109% or more. By doing so, the amount of oxygen present in the internal space of the monoblock housing 12 that dissolves into the electrolyte 36 is reduced, and the oxidation of zinc in the negative electrode active material layer 20a is suppressed, thereby improving the battery life.

[0041] 10: Battery module, 12: Monoblock housing, 12a: Bottom, 12b: Long side wall, 12c: Short side wall, 12d: Cover, 12e: Rib, 12f: Partition, 14: Electrode stack, 14a: Unit cell, 16: Positive electrode plate, 16a: Positive electrode active material layer, 16b: Positive electrode current collector, 18: Positive electrode tab lead, 19: Positive electrode tab junction, 20: Negative electrode plate, 20a: Negative electrode Active material layer, 20b: Negative electrode current collector, 22: Negative electrode tab lead, 23: Negative electrode tab joint, 24: Hydroxide ion conductive separator, 26: Insulating tape, 28: Liquid retention member, 30: Terminal joint, 30a: Connection terminal, 30aa: Vertical part, 30ab: Horizontal part, 30b: Joint, 32: Resin, 34: Electrode pole terminal, 36: Electrolyte, U: Uncoated area, W: Welded joint

Claims

1. A monoblock housing; a plurality of vertically elongated electrode stacks housed vertically within the monoblock housing and arranged parallel to each other, wherein each electrode stack comprises: a positive electrode plate including a positive electrode active material layer and a positive electrode current collector; a positive electrode tab lead extending from the end of the positive electrode plate; a negative electrode plate provided opposite the positive electrode plate and including a negative electrode active material layer and a negative electrode current collector, which includes at least one selected from the group consisting of zinc, zinc oxide, zinc alloy and zinc compounds; a negative electrode tab lead extending from the end of the negative electrode plate at a position that does not overlap with the positive electrode tab lead; and a hydroxide ion conductive separator that isolates the positive electrode plate and the negative electrode plate in a manner that allows hydroxide ion conduction; a plurality of terminal connectors that connect adjacent electrode stacks in the plurality of electrode stacks in series via the positive electrode tab lead and / or the negative electrode tab lead; and an electrolyte filled within the monoblock housing in which the electrode stacks are immersed. A battery module in which each of the terminal junctions is composed of a pair of connection terminals connected to an adjacent electrode stack, the pair of connection terminals are joined to each other to form a joint, and the joint is covered and reinforced with resin.

2. The battery module according to claim 1, wherein each of the connection terminals has an L-shape.

3. The battery module according to claim 2, wherein each of the connection terminals has a vertical portion that is joined to the positive electrode tab lead or the negative electrode tab lead and extends upward, and a horizontal portion that extends horizontally from the upper end of the vertical portion, and the joining portion is formed in the horizontal portion.

4. The battery module according to claim 1, wherein the joint portion is embedded in the resin.

5. The battery module according to any one of claims 1 to 4, wherein the resin comprises an epoxy resin and / or an olefin resin.

6. The battery module according to any one of claims 1 to 4, wherein the connection terminal is made of copper.

7. The battery module according to any one of claims 1 to 4, wherein the pair of connection terminals are welded to each other at the joint.

8. The battery module according to any one of claims 1 to 4, wherein the monoblock housing has a bottom, a pair of longitudinal side walls parallel to the stacking direction of the electrode stack, a pair of transverse side walls perpendicular to the stacking direction of the electrode stack, and a lid, and the plurality of electrode stacks are housed in an exposed state within one monoblock housing without each being housed in an individual single cell case.

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