JP2020095955A - Alkaline secondary battery - Google Patents

Abstract

To provide an alkaline secondary battery that has a shape suitable for applying pressure when used as a module battery, and that can ensure excellent heat dissipation.SOLUTION: An alkaline secondary battery 10 includes a laminated battery in which a plurality of unit cell elements having a configuration of the alkaline secondary battery are laminated, and a box-shaped case 28 in which the laminated battery is housed vertically, and the box-shaped case includes a bottom portion 28a, a pair of long-side wall portions 28b parallel to the laminated battery, a pair of short-side wall portions 28c perpendicular to the laminated battery, and a lid portion 28d, and the outer surface of the pair of long-side wall portions has a flat surface and a plurality of ribs R provided so as to project in a ridge shape from the flat surface, and the plurality of ribs are spaced from each other and provided in parallel in the longitudinal direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to an alkaline secondary battery.

In order to obtain a high voltage and a large current, a laminated battery made by combining a plurality of single cells is widely adopted. The laminated battery has a structure in which a laminated body in which a plurality of unit cells are connected in series or in parallel is housed in one battery container. For example, Patent Document 1 (International Publication No. WO 2017/086278) discloses a zinc secondary battery in which a plurality of electrode cartridges each including an electrode and a separator (especially an LDH separator described later) are housed in a sealed container. There is.

Further, in order to further increase the capacity and output, it is also common to arrange a plurality of battery units having a laminated battery therein to form a battery module. For example, Patent Document 2 (International Publication No. 2018/173110) discloses a battery module in which a plurality of rectangular parallelepiped battery units are housed in a frame structure, and a plurality of alkaline batteries are contained in the battery unit. It is said that the unit cells of the secondary battery (for example, nickel-zinc secondary battery and zinc-air secondary battery) are preferably accommodated in the form of an assembled battery or a battery module.

By the way, in a zinc-zinc secondary battery such as a nickel-zinc secondary battery or an air-zinc secondary battery, metallic zinc is deposited in a dendrite form from the negative electrode during charging and reaches the positive electrode through the voids of a separator such as a nonwoven fabric, As a result, it is known to cause a short circuit. Such a short circuit caused by zinc dendrite causes repeated shortening of charge/discharge life. In order to deal with the above problem, a battery provided with a layered double hydroxide (LDH) separator that prevents penetration of zinc dendrite while selectively allowing hydroxide ions to pass through has been proposed. For example, Patent Document 3 (International Publication No. 2013/118561) discloses providing an LDH separator between a positive electrode and a negative electrode in a nickel-zinc secondary battery. Further, Patent Document 4 (International Publication No. 2016/076047) discloses a separator structure including an LDH separator fitted or joined to a resin outer frame, and the LDH separator has gas impermeability and It is disclosed to have a high degree of compaction such that it has water/impermeable properties. This document also discloses that the LDH separator can be composited with a porous substrate. Further, Patent Document 5 (International Publication No. WO 2016/067884) discloses various methods for forming a LDH dense film on the surface of a porous substrate to obtain a composite material (LDH separator). In this method, a starting material that can give a starting point for LDH crystal growth is uniformly attached to a porous substrate, and the porous substrate is hydrothermally treated in an aqueous solution of the raw material to form an LDH dense film on the surface of the porous substrate. It includes a step of forming.

International Publication No. 2017/0886278 International Publication No. 2018/173110 International Publication No. 2013/118561 International Publication No. 2016/076047 International Publication No. 2016/067884

By the way, in a battery unit including a laminated battery such as a nickel-zinc battery in the case, it is desirable to apply pressure from outside the case in order to maximize the battery performance. This is because the gap that allows the growth of zinc dendrites between the negative electrode and the LDH separator can be minimized, and thereby more effective prevention of zinc dendrite extension can be expected. For that purpose, it is desirable that the side surface shape of the case be as flat as possible so that pressure is applied to each battery unit when a plurality of battery units are arranged and modularized. For example, a rectangular parallelepiped case 128 as shown in FIG. However, if the side surface of the case 128 is flat, the battery units that form the module 130 will come into close contact with each other as shown in FIG. 11, so that the heat generated by the battery units cannot be dissipated well, that is, There is a problem that heat dissipation becomes poor.

The present inventors have recently provided a plurality of ribs on the flat outer surface of the long side wall of the box-shaped case, so that the module battery has a shape suitable for applying pressure when formed into a module battery. We have found that it is possible to provide an alkaline secondary battery that can ensure excellent heat dissipation.

Therefore, it is an object of the present invention to provide an alkaline secondary battery that has a shape suitable for applying pressure when it is formed into a battery module, and that can ensure excellent heat dissipation.

According to one aspect of the invention,
A stacked battery in which a plurality of single battery elements having a structure of an alkaline secondary battery are stacked,
A box-shaped case in which the laminated battery is accommodated in a vertical direction,
An alkaline secondary battery comprising:
The box-shaped case has a bottom portion, a pair of long side wall portions parallel to the laminated battery, a pair of short side wall portions perpendicular to the laminated battery, and a lid portion,
The outer surface of the pair of long side wall portions has a flat surface and a plurality of ribs provided in a ridge-like shape protruding from the flat surface, and the plurality of ribs are provided so as to be separated from each other and parallel to the longitudinal direction. The alkaline secondary battery is provided.

According to another aspect of the present invention, an alkaline secondary battery module comprising a plurality of the alkaline secondary battery,
The plurality of alkaline secondary batteries, the long side wall portions are opposed to each other, and are arranged so that the ribs contact each other, thereby forming a spacer by contacting the ribs of the adjacent box-shaped case, Thus, an alkaline secondary battery module having vertical ventilation holes is provided.

It is a perspective view which shows an example of the alkaline secondary battery of this invention. It is the sectional view on the AA line of the box type case of the alkaline secondary battery shown in FIG. It is a top view which shows the cover part of the box type case of the alkaline secondary battery shown in FIG. FIG. 2 is a perspective view showing a battery module in which a plurality of alkaline secondary batteries shown in FIG. 1 are arranged. It is a perspective view which shows an example of an internal structure of the alkaline secondary battery shown by FIG. FIG. 6 is a schematic cross-sectional view conceptually showing the layer structure of the alkaline secondary battery shown in FIG. 5. The external appearance and internal structure of the alkaline secondary battery shown in FIG. 5 are shown. FIG. 3 is a perspective view showing an example of a negative electrode plate used in an alkaline secondary battery and having a negative electrode active material layer covered with an LDH separator. It is a schematic cross section which shows the laminated constitution of the negative electrode plate shown by FIG. 8A. It is a schematic diagram for demonstrating the area|region covered with the LDH separator in the negative electrode plate shown by FIG. 8A. It is a perspective view which shows the conventional rectangular parallelepiped battery unit. It is a perspective view showing a battery module in which a plurality of conventional rectangular parallelepiped battery units are arranged. It is a figure which shows one form of the cross section of the box type case of the alkaline secondary battery shown by FIG.

Alkaline Secondary Battery FIG. 1 shows an example of the alkaline secondary battery of the present invention. The alkaline secondary battery 10 shown in FIG. 1 includes a laminated battery and a box-shaped case 28 in which the laminated battery is housed vertically. As shown in FIGS. 5 and 6, the laminated battery is obtained by laminating a plurality of unit cell elements 11 having an alkaline secondary battery structure, and is advantageous in that a high voltage and a large current can be obtained. As shown in FIGS. 1 to 3, the box-shaped case 28 includes a bottom portion 28a, a pair of long side wall portions 28b parallel to the stacked battery, a pair of short side wall portions 28c perpendicular to the stacked battery, and a lid. And a portion 28d. The outer surface of the pair of long side wall portions 28b has a flat surface F and a plurality of ribs R projecting from the flat surface 38f in a ridge shape. It is provided parallel to the direction. As described above, by providing the plurality of ribs R on the flat outer surface of the long side wall portion 28b of the box-shaped case 28, it is suitable to apply pressure when the battery module 30 is formed as shown in FIG. It is possible to provide an alkaline secondary battery which has a good shape but can ensure excellent heat dissipation.

As described above, it is desirable that the battery unit including the laminated battery such as the nickel-zinc battery in the case be pressurized from the outside of the case in order to maximize the battery performance. For that purpose, it is desirable that the side surface shape of the case be as flat as possible so that pressure is applied to each battery unit when a plurality of battery units are arranged and modularized. For example, a rectangular parallelepiped case 128 as shown in FIG. However, if the side surface of the case is flat, the battery units forming the module 130 will come into close contact with each other as shown in FIG. 11, and the heat generated by the battery units cannot be dissipated well. In this regard, in the alkaline secondary battery 10 of the present invention, by providing a plurality of ribs R on the flat outer surface of the long side wall portion 28b, the long side wall portion is formed when the battery module 30 is formed as shown in FIG. 28b may face each other, and ribs R may be arranged to contact each other. As a result, the ribs R of the adjacent box-shaped cases 28 are in contact with each other to form a spacer, whereby vertical ventilation holes can be formed, and excellent heat dissipation can be ensured. In particular, this excellent heat dissipation property can be more desirably realized by allowing air to pass through the gap between the ribs R from below the battery module 30 in the direction of the arrow as shown in FIG. Thus, while ensuring excellent heat dissipation, by pressing the long side wall portion 28b from the outside of the battery module 30 in the thickness direction, the box-shaped case 28 bends to apply pressure to the single cell element 11. You can

Therefore, according to a preferred embodiment of the present invention, as shown in FIG. 4, an alkaline secondary battery module 30 provided with a plurality of alkaline secondary batteries 10 is provided. In this aspect, the plurality of alkaline secondary batteries are arranged such that the long side wall portions 28b face each other and the ribs R contact each other, whereby the ribs R of the adjacent box-shaped cases 28 contact each other. It forms a spacer, thereby forming a longitudinal ventilation hole. Preferably, a pressurizing means (not shown) for pressurizing the longitudinal side wall portion 28b in the thickness direction is provided outside the alkaline secondary battery module 30, whereby the box-shaped case 28 is pressed by the pressurizing means. The cell element 11 is pressed by being bent.

As shown in FIGS. 1 to 3, the box-shaped case 28 includes a bottom portion 28a, a pair of long side wall portions 28b parallel to the laminated battery, a pair of short side wall portions 28c perpendicular to the laminated battery, and a lid portion. 28d. Preferably, the alkaline secondary battery 10 further includes a positive electrode terminal 14c and a negative electrode terminal 18c, and the positive electrode terminal 14c and the negative electrode terminal 18c are extended from the lid portion 28d. Although the laminated battery is not shown in FIGS. 1 to 3, it is a stack of a plurality of unit cell elements 11 as shown in FIGS. 5 and 6, that is, an assembly of a plurality of unit cell elements 11. Although the typical basic shape of the box-shaped case 28 is a rectangular parallelepiped, it does not have to be a perfect rectangular parallelepiped, and as long as the overall shape is a box, it may be a shape that partially has a curved surface or unevenness. It may be.

The box-shaped case 28 is preferably made of resin. The resin forming the box-shaped case 28 is preferably a resin having resistance to an alkali metal hydroxide such as potassium hydroxide, more preferably a polyolefin resin, an ABS resin, or a modified polyphenylene ether, further preferably ABS. It is a resin or modified polyphenylene ether. Further, a case group in which two or more cases 28 are arranged may be housed in an outer frame to form a battery module.

The outer surface of the pair of long side wall portions 28b has a flat surface F and a plurality of ribs R provided so as to project from the flat surface F in a ridge shape. A plurality of ribs R are provided so as to be separated from each other and parallel to the vertical direction. The rib R preferably has a height of 1.0 to 10 mm based on the flat surface F, more preferably 1.0 to 4.0 mm, further preferably 1.2 to 3.5 mm, and particularly preferably 1 0.4-3.0 mm, most preferably 1.5-2.5 mm. Within these ranges, the heat dissipation when the battery module 30 is constructed is excellent, and the battery energy density can be improved by minimizing the wasted space. The width of the rib R is preferably 2.5 to 8.0 mm, more preferably 3.0 to 7.5 mm, and further preferably 3.5 to 7.0 mm from the viewpoint of ensuring both heat dissipation and pressure application. , Particularly preferably 4.0 to 6.5 mm, most preferably 4.5 to 6.0 mm.

The rib R is provided such that the width of the rib R gradually or gradually increases in the direction from the bottom portion 28a to the lid portion 28d. This is because the rib R is easily released from the mold when the box-shaped case 28 is manufactured. preferable. Further, the cross-sectional shape of the rib R may be any shape such as a rectangular shape, a curved surface shape, a trapezoidal shape, etc., but the trapezoidal shape is preferable from the viewpoint of releasing from the mold.

The number of the ribs R per one of the long side wall portions 28b is not particularly limited, but is preferably 5 to 11, more preferably 7 to 10, and further preferably 8 to 9. When the number of ribs R per one of the long side wall portions 28b is 5 or more, the rib R closest to the left end of the long side wall portion 28b (the connection portion with the short side wall portion 28c) and the second closest to this left end. distance D _L between the ribs _R, and the distance D _R of the right edge nearest rib R in the (connection portion between the short side wall portion 28c) and the ribs R is second closest to the right end of the longitudinal side wall section 28b is, the longitudinal side walls narrow it is preferable than the distance D _M other ribs R each other away from the ends (i.e. left and right) parts 28b. By doing so, the portions in the vicinity of both ends of the long side wall portion 28b of the box-shaped case 28 (that is, the portion in the vicinity of the short side wall portion 28c) can be locally reinforced, and abnormal operation such as overcharging, overdischarging, or a short circuit occurs. It is possible to suppress the expansion of the box-shaped case 28 (in particular, the expansion of the case 28 in the thickness direction) due to the gas generated in the battery. In particular, a surplus space where the electrodes do not reach is likely to be formed in the vicinity of both ends of the long side wall portion 28b, and the gas generated at the time of abnormality is accumulated in the surplus space, and excessive internal pressure may be intensively applied to the box-shaped case 28. However, it is possible to provide the box-shaped case 28 with strength that can withstand such internal pressure.

By the way, when the width of the rib R is provided so as to gradually or gradually increase in the direction from the bottom portion 28a to the lid portion 28d, as shown in FIG. 12, the pair of long side wall portions 28b are The pair of long side wall portions 28b facing each other through the battery element 11 has a tapered cross-sectional shape in which the distance between the inner walls of the long side wall portions 28b gradually or gradually decreases in the direction from the lid portion 28d to the bottom portion 28a. Preferably. That is, as described above, in order to maximize the battery performance, by pressing the long side wall portion 28b from the outside of the battery module 30 in the thickness direction, the box-shaped case 28 bends and the pressure is applied to the single cell element 11. It is desirable to give it. However, according to the knowledge of the present inventors, when the width of the rib R is provided so as to gradually or gradually increase in the direction from the bottom portion 28a to the lid portion 28d, the larger the width of the rib R is, the more the portion is formed. Tend to be more strongly pressurized. As a result, the pressure applied to the single cell element 11 by the box-shaped case 28 may be non-uniform. Therefore, by providing the longitudinal side wall portions 28b with a tapered cross-sectional shape in which the distance between the inner walls of the pair of longitudinal side wall portions 28b decreases in the direction from the lid portion 28d to the bottom portion 28a, pressurization is relatively performed. The lower portion that becomes weaker can have a narrow inner wall distance in advance, while the upper portion that the pressure can be relatively strong can have a wide inner wall distance in advance. By doing so, when the box-shaped case 28 is actually pressed in the thickness direction (in the direction indicated by the arrow in FIG. 12 ), the distribution of the distances between the inner walls which is given in advance by the tapered cross section is The pressure distributions can be conveniently offset. In other words, the wide inner wall distance above the long side wall portion 28b transmits the relatively strong pressure to the single cell element 11 while relaxing the relatively strong pressure, while the narrow inner wall distance below the long side wall portion 28b applies the relatively weak pressure to the single cell element. 11 will be more directly communicated. In this way, the pressure applied to the unit cell element 11 via the box-shaped case 28 (specifically, the pair of long side wall portions 28b) can be made uniform regardless of the height. Therefore, according to such a configuration, in addition to the effect of the rib R that is excellent in heat dissipation when the battery module 30 is configured, it is also possible to achieve uniform electrode pressurization. That is, it is possible to provide the box-shaped case 28 having both heat dissipation (cooling) and pressurization.

As shown in FIG. 1, the short side wall portion 28c preferably has a fragile portion W whose thickness is locally reduced as compared with other portions of the short side wall portion 28c. In this case, the fragile portion W is formed. Is more preferably provided near the upper end of the short side wall portion 28c. Alternatively, as shown in FIG. 3, it is also preferable that the lid portion 28d has a fragile portion W whose thickness is locally reduced as compared with other portions of the lid portion 28d, and in this case, the positive electrode terminal 14c and the negative electrode. More preferably, the weakened portion W is provided between the terminals 18c. Both the short side wall portion 28c and the lid portion 28d may have the fragile portion W. By having the fragile portion W, the fragile portion W is selectively destroyed by the internal pressure when the internal pressure excessively rises due to the gas generated in the battery during abnormal operation such as overcharge, overdischarge, and short circuit. It is possible to prevent or minimize leakage of the electrolytic solution and limit the reinforcing portion of the module housing (not shown) that houses the alkaline secondary battery 10 or the battery module 30 to a specific portion or surface near the weakened portion W. Yes (that is, you don't have to reinforce the entire module housing). The fragile portion W may be provided on the long side wall portion 28b. However, the fragile portion W provided on the short side wall portion 28c and the lid portion 28d has a higher opening pressure than the fragile portion W provided on the long side wall portion 28b. Is stable (variation in opening pressure is small), which is preferable. That is, when the long side wall portion 28b is provided with the fragile portion W, pressure is applied to the long side wall portion 28b including the fragile portion W when the battery module 30 is configured, and therefore, extra stress other than the battery internal pressure is applied, and the open state is achieved. Pressure is not stable. On the other hand, in the short side wall portion 28c and the lid portion 28d, even if the battery module 30 is configured, no force other than the battery internal pressure is applied, so that the opening pressure of the weak portion W can be stabilized.

The preferable thickness of the box-shaped case 28 (particularly the short side wall portion 28c and the lid portion 28d) other than the fragile portion W is 1.0 to 4.5 mm, more preferably 1.5 to 3.5 mm, and It is preferably 2.0 to 2.5 mm. The fragile portion W has a preferable thickness of 0.1 to 1.0 mm, more preferably 0.2 to 0.9 mm, and further preferably 0.3 to 0.8 mm. The thickness of the fragile portion W is preferably 0.10 to 0.32 times the thickness of the portion other than the fragile portion W of the short side wall portion 28c or the lid portion 28d, and more preferably 0.13 to. 0.26 times, more preferably 0.15 to 0.22 times.

The alkaline secondary battery 10 is not particularly limited as long as it is a secondary battery using an alkaline electrolyte (typically an aqueous solution of an alkali metal hydroxide), but a zinc secondary battery using zinc as a negative electrode is preferable. Therefore, it can be a nickel zinc secondary battery, a silver oxide zinc secondary battery, a manganese zinc zinc secondary battery, and various other alkaline zinc secondary batteries. For example, it is preferable that the positive electrode contains nickel hydroxide and/or nickel oxyhydroxide, so that the zinc secondary battery forms a nickel zinc secondary battery.

A case where the alkaline secondary battery 10 is a zinc secondary battery will be described below with reference to FIGS. The alkaline secondary battery 10 (that is, a zinc secondary battery) shown in FIGS. 5 to 7 includes a single cell element 11, and the single cell element 11 includes a positive electrode plate 12, a negative electrode plate 16, and a layered double hydroxide ( LDH) separator 22 and an electrolytic solution (not shown). The positive electrode plate 12 includes a positive electrode active material layer 13 and, if desired, a positive electrode current collector 14. The negative electrode plate 16 includes a negative electrode active material layer 17 and optionally a negative electrode current collector 18, and the negative electrode active material layer 17 includes at least one selected from the group consisting of zinc, zinc oxide, a zinc alloy and a zinc compound. .. The positive electrode active material layer 13 and the negative electrode active material layer 17 are separated from each other by the LDH separator 22. For example, the LDH separator 22 preferably covers or encloses the entire negative electrode active material layer 17. In the present specification, the "LDH separator" is a separator containing LDH, and is defined as a separator that selectively utilizes hydroxide ion conductivity of LDH to selectively pass hydroxide ions. Typically, each of the positive electrode active material layer 13, the negative electrode active material layer 17, and the LDH separator 22 has a quadrilateral shape (typically, a quadrangular shape). Preferably, the positive electrode current collector 14 has a positive electrode current collector tab 14 a extending from one side of the positive electrode active material layer 13, and the negative electrode current collector 18 is the positive electrode current collector tab 14 a of the negative electrode active material layer 17. It has a negative electrode current collecting tab 18a extending from one side on the opposite side and beyond the end of the LDH separator 22. As a result, it is preferable that the unit cell element 11 can collect current from opposite sides via the positive electrode current collecting tab 14a and the negative electrode current collecting tab 18a. Furthermore, it is preferable that the outer edges of at least two sides C of the LDH separator 22 adjacent to each other (except one side overlapping with the negative electrode current collecting tab) be closed. With such a configuration, a zinc secondary battery (particularly, a laminated battery thereof) capable of preventing zinc dendrite extension can be easily assembled without collecting complicated sealing joint between the LDH separator 22 and the battery container. It can be provided with an easy and simple structure.

The positive electrode plate 12 includes a positive electrode active material layer 13. For the positive electrode active material layer 13, a known positive electrode material may be appropriately selected according to the type of zinc secondary battery and is not particularly limited. For example, in the case of a nickel-zinc secondary battery, a positive electrode containing nickel hydroxide and/or nickel oxyhydroxide may be used. The positive electrode plate 12 further includes a positive electrode current collector (not shown), and the positive electrode current collector has a positive electrode current collector tab 14 a extending from one side of the positive electrode active material layer 13. A preferable example of the positive electrode current collector is a nickel porous substrate such as a foamed nickel plate. In this case, for example, a positive electrode plate composed of a positive electrode/a positive electrode current collector can be preferably manufactured by uniformly applying a paste containing an electrode active material such as nickel hydroxide on a nickel porous substrate and drying the paste. .. At this time, it is also preferable to press the dried positive electrode plate (that is, the positive electrode/positive electrode current collector) to prevent the electrode active material from falling off and improve the electrode density. Although the positive electrode plate 12 shown in FIG. 6 includes a positive electrode current collector (for example, nickel foam), it is not shown. This is because the positive electrode current collector is naturally integrated with the positive electrode active material layer 13, and thus the positive electrode current collector cannot be drawn individually. The alkaline secondary battery 10 preferably further includes a positive electrode current collector plate 14b connected to the tip of the positive electrode current collector tab 14a, and more preferably a plurality of positive electrode current collector tabs 14a connected to one positive electrode current collector plate 14b. To be done. By doing so, current can be collected in a space-efficient manner with a simple structure, and connection to the positive electrode terminal 14c is facilitated. Further, the positive electrode current collector plate 14b itself may be used as the negative electrode terminal.

The negative electrode plate 16 includes a negative electrode active material layer 17. The negative electrode active material layer 17 contains at least one selected from the group consisting of zinc, zinc oxide, a zinc alloy, and a zinc compound. That is, zinc may be contained in any form of zinc metal, zinc compound and zinc alloy as long as it has electrochemical activity suitable for the negative electrode. Preferred examples of the negative electrode material include zinc oxide, zinc metal, calcium zincate and the like, but a mixture of zinc metal and zinc oxide is more preferred. The negative electrode active material layer 17 may be formed into a gel or may be mixed with an electrolytic solution to form a negative electrode mixture. For example, a gelled negative electrode can be easily obtained by adding an electrolytic solution and a thickener to the negative electrode active material. Examples of the thickener include polyvinyl alcohol, polyacrylic acid salt, CMC, alginic acid and the like, but polyacrylic acid is preferable because it has excellent chemical resistance to strong alkali.

As the zinc alloy, a zinc alloy containing no mercury and lead, which is known as a smoothing-free zinc alloy, can be used. For example, a zinc alloy containing 0.01 to 0.1% by mass of indium, 0.005 to 0.02% by mass of bismuth, and 0.0035 to 0.015% by mass of aluminum has an effect of suppressing hydrogen gas generation. Therefore, it is preferable. In particular, indium and bismuth are advantageous in improving discharge performance. When the zinc alloy is used for the negative electrode, the self-dissolution rate in the alkaline electrolytic solution is slowed to suppress the generation of hydrogen gas and improve the safety.

The shape of the negative electrode material is not particularly limited, but it is preferably in the form of powder, which increases the surface area and can cope with large current discharge. In the case of zinc alloy, the preferable average particle diameter of the negative electrode material is within the range of 3 to 100 μm in the short diameter, and since the surface area is large within this range, it is suitable for large current discharge, and the electrolyte and gel Easy to mix with the agent and easy to handle when assembling the battery.

The negative electrode plate 16 may further include a negative electrode current collector 18. Preferably, the negative electrode current collector 18 has a negative electrode current collector tab 18 a extending from one side of the negative electrode active material layer 17 opposite to the positive electrode current collector tab 14 a and beyond the end of the LDH separator 22. As a result, the unit cell element 11 can collect current from opposite sides via the positive electrode current collecting tab 14a and the negative electrode current collecting tab 18a. The alkaline secondary battery 10 preferably further includes a negative electrode current collector plate 18b connected to the tip of the negative electrode current collector tab 18a, and more preferably a plurality of negative electrode current collector tabs 18a connected to one negative electrode current collector plate 18b. To be done. By doing so, current can be collected in a space-efficient manner with a simple structure, and connection to the negative electrode terminal 18c is facilitated. Alternatively, the negative electrode current collector plate 18b itself may be used as the negative electrode terminal. Typically, the tip portion of the negative electrode current collecting tab 18a forms an exposed portion that is not covered with the LDH separator 22 and the liquid retaining member 20 (if present). Thereby, the negative electrode collector 18 (particularly the negative electrode collector tab 18a) can be desirably connected to the negative electrode collector plate 18b and/or the negative electrode terminal 18c through the exposed portion. In this case, as shown in FIG. 9, the LDH separator 22 is provided with a predetermined margin M (for example, an interval of 1 to 5 mm) so as to sufficiently hide the end portion of the negative electrode active material layer 17 on the negative electrode current collector tab 18a side. Covering or wrapping is preferred. This makes it possible to more effectively prevent the zinc dendrite from extending from the end of the negative electrode active material layer 17 on the negative electrode current collector tab 18a side or in the vicinity thereof.

Preferable examples of the negative electrode current collector 18 include copper foil, copper expanded metal, and copper punching metal, and more preferably copper expanded metal. In this case, for example, a negative electrode composed of a negative electrode/negative electrode current collector by coating a mixture containing zinc oxide powder and/or zinc powder and optionally a binder (for example, polytetrafluoroethylene particles) on a copper expanded metal. The plate can be preferably manufactured. At that time, it is also preferable to press the dried negative electrode plate (that is, the negative electrode/negative electrode current collector) to prevent the electrode active material from falling off and improve the electrode density.

The alkaline secondary battery 10 as a zinc secondary battery further includes a liquid retaining member 20 that is interposed between the negative electrode active material layer 17 and the LDH separator 22 and covers or wraps the entire negative electrode active material layer 17. preferable. By doing so, the electrolytic solution can be made to exist evenly between the negative electrode active material layer 17 and the LDH separator 22, and the exchange of hydroxide ions between the negative electrode active material layer 17 and the LDH separator 22 can be performed. It can be done efficiently. The liquid retaining member 20 is not particularly limited as long as it is a member that can retain the electrolytic solution, but a sheet-shaped member is preferable. Preferred examples of the liquid retaining member include a nonwoven fabric, a water absorbent resin, a liquid retaining resin, a porous sheet, and various spacers, but a nonwoven fabric is particularly preferable in that a negative electrode structure having good performance can be produced at low cost. .. The liquid retaining member 20 preferably has a thickness of 0.01 to 0.20 mm, more preferably 0.02 to 0.20 mm, further preferably 0.02 to 0.15 mm, and particularly preferably It is 0.02-0.10 mm, and most preferably 0.02-0.06 mm. When the thickness is within the above range, it is possible to hold a sufficient amount of the electrolytic solution in the liquid retaining member 20 while keeping the overall size of the negative electrode structure compact without waste.

The entire negative electrode active material layer 17 is preferably covered or wrapped with the LDH separator 22. 8A and 8B show a preferred embodiment of the negative electrode plate 16 in which the negative electrode active material layer 17 is covered or wrapped with the LDH separator 22. The negative electrode structure shown in FIGS. 8A and 8B includes a negative electrode active material layer 17, a negative electrode current collector 18, and, if desired, a liquid retaining member 20, and the entire negative electrode active material layer 17 (if necessary, It is covered or encapsulated by an LDH separator 22 (via the liquid member 20). In this manner, by covering or wrapping the entire negative electrode active material layer 17 with the LDH separator 22 (via the liquid retaining member 20 as necessary), as described above, the LDH separator 22 and the battery container are complicated. It is possible to manufacture a zinc secondary battery (particularly, a laminated battery thereof) capable of preventing zinc dendrite extension without using sealing and bonding, with extremely high productivity.

8A and 8B, the liquid retaining member 20 is drawn as a smaller size than the LDH separator 22, but the liquid retaining member 20 may be the same size as the LDH separator 22 (or the folded LDH separator 22), The outer edge of the liquid retaining member 20 can reach the outer edge of the LDH separator 22. That is, the outer peripheral portion of the liquid retaining member 20 may be sandwiched between the LDH separators 22 forming the outer peripheral portion. By doing so, the outer edge sealing of the LDH separator 22 described later can be effectively performed by thermal welding or ultrasonic welding. That is, rather than directly heat-welding or ultrasonically welding the LDH separators 22 to each other, the LDH separators 22 are indirectly heat-welded or ultrasonically welded by interposing the heat-welding liquid retaining member 20 therebetween. By doing so, as a result of being able to utilize the heat-welding property of the liquid retaining member 20 itself, more effective sealing can be performed. For example, the end to be sealed of the liquid retaining member 20 can be used as if it is a hot melt adhesive. A preferred example of the liquid retaining member 20 in this case is a non-woven fabric, particularly a non-woven fabric made of a thermoplastic resin (for example, polyethylene or polypropylene).

The LDH separator 22 includes LDH and a porous base material. As mentioned above, the LDH separator 22 is such that it exhibits hydroxide ion conductivity and gas impermeability (and thus functions as an LDH separator exhibiting hydroxide ion conductivity). Is blocking. The porous substrate is preferably made of a polymeric material, and LDH is particularly preferably incorporated throughout the thickness of the polymeric porous substrate. For example, known LDH separators disclosed in Patent Documents 3 to 5 can be used.

The number of LDH separators 22 for one negative electrode active material layer 17 is typically 1 (two facing each other on both sides or one bent) on one side, but it may be two or more. For example, the entire negative electrode active material layer 17 (which may be covered or wrapped with the liquid retaining member 20) may be covered or wrapped with a plurality of stacked LDH separators 22.

As described above, the LDH separator 22 has a quadrilateral (typically quadrangular) shape. Then, the outer edges of at least two sides C of the LDH separator 22 that are adjacent to each other (except one side overlapping with the negative electrode current collector tab 18a) are closed. By doing so, the negative electrode active material layer 17 can be reliably separated from the positive electrode plate 12, and extension of the zinc dendrite can be prevented more effectively. One side overlapping with the negative electrode current collecting tab 18a is removed from the side C to be closed in order to allow the negative electrode current collecting tab 18a to extend.

According to a preferred aspect of the present invention, the positive electrode plate 12, the negative electrode plate 16, and the LDH separator 22 are oriented vertically, and one side C of the closed outer edge of the LDH separator 22 is the lower end. The elements 11 are arranged so that the positive electrode current collecting tabs 14a and the negative electrode current collecting tabs 18a extend laterally from opposite side ends of the unit cell elements 11. By doing so, it becomes easier to collect current, and when one side of the upper edge of the outer edge of the LDH separator 22 is opened (this will be described later), there is no obstacle in the upper open portion, so that the positive electrode plate 12 and It becomes easier for gas to flow into and out of the negative electrode plate 16.

By the way, one side or two sides of the outer edge of the LDH separator 22 may be opened. For example, even if the upper edge of the outer edge of the LDH separator 22 is left open, if the electrolyte is injected so as not to reach the upper edge of the zinc secondary battery during the fabrication of the zinc secondary battery, the electrolytic charge will be applied to the upper edge of the LDH separator 22. Since there is no liquid, problems such as liquid leakage and zinc dendrite extension can be avoided. In this regard, the unit cell element 11 is housed together with the positive electrode plate 12 in the case 28 which may be a closed container, and is closed by the lid portion 28d to function as a main component of the closed zinc secondary battery. sell. For this reason, it is sufficient to ensure the airtightness in the case 28 that will be finally accommodated, and therefore the unit cell element 11 itself can have a simple structure of an upper open type. Further, by leaving one side of the outer edge of the LDH separator 22 open, the negative electrode current collecting tab 18a can be extended therefrom.

The outer edge of one side, which is the upper end of the LDH separator 22, is preferably opened. This open-top configuration makes it possible to address the problem of overcharging in nickel-zinc batteries and the like. That is, when overcharged in a nickel-zinc battery or the like, oxygen (O ₂ ) may be generated in the positive electrode plate 12, but the LDH separator 22 has a high degree of denseness that substantially only allows hydroxide ions to pass therethrough. , O ₂ is not passed. In this respect, according to the open-top configuration, O ₂ can escape to the upper side of the positive electrode plate 12 in the case 28 and be sent to the negative electrode plate 16 side through the upper open portion, whereby O ₂ Zn in the negative electrode active material layer 17 can be oxidized and returned to ZnO. Through such an oxygen reaction cycle, it is possible to improve the overcharge resistance by using the open-top type single cell element 11 in the sealed zinc secondary battery. Even when the outer edge of one side that is the upper end of the LDH separator 22 is closed, the same effect as that of the open-type configuration can be expected by providing a ventilation hole in a part of the closed outer edge. .. For example, the vent hole may be opened after sealing the outer edge of one side which is the upper end of the LDH separator 22, or at the time of sealing, a part of the outer edge is not sealed so that the vent hole is formed. Good.

In any case, it is preferable that the closed side C of the outer edge of the LDH separator 22 is realized by bending the LDH separator 22 and/or sealing the LDH separators 22. Preferred examples of sealing techniques include adhesives, heat welding, ultrasonic welding, adhesive tapes, sealing tapes, and combinations thereof. In particular, the LDH separator 22 including a porous base material made of a polymer material has an advantage that it is easy to bend because it has flexibility, and therefore, by forming the LDH separator 22 in a long shape and bending it, It is preferable to form a closed state at one side C. The heat welding and the ultrasonic welding may be performed using a commercially available heat sealer or the like, but in the case of sealing the LDH separators 22 with each other, the outer peripheral portion of the liquid retaining member 20 is sandwiched between the LDH separators 22 forming the outer peripheral portion. It is preferable to perform the heat welding and the ultrasonic welding in this way in terms of more effective sealing. On the other hand, as the adhesive, the adhesive tape, and the sealing tape, commercially available products may be used, but those containing a resin having alkali resistance are preferable in order to prevent deterioration in an alkaline electrolyte. 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 resistant. It is more preferable because it is particularly excellent in alkalinity. Examples of epoxy resin adhesive products include epoxy adhesive Hysol (registered trademark) (manufactured by Henkel).

The electrolytic solution preferably contains an aqueous alkali metal hydroxide solution. The electrolytic solution is not shown in the figure, but this is because it is spread over the whole of the positive electrode plate 12 (in particular, the positive electrode active material layer 13) and the negative electrode plate 16 (in particular, the negative electrode active material layer 17). Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide and the like, and potassium hydroxide is more preferable. In order to suppress self-dissolution of zinc and/or zinc oxide, a zinc compound such as zinc oxide or zinc hydroxide may be added to the electrolytic solution. As described above, the electrolytic solution may be mixed with the positive electrode active material and/or the negative electrode active material and may be present in the form of the positive electrode composite material and/or the negative electrode composite material. Further, the electrolytic solution may be gelled in order to prevent leakage of the electrolytic solution. As the gelling agent, it is desirable to use a polymer that absorbs the solvent of the electrolytic solution and swells, and polymers such as polyethylene oxide, polyvinyl alcohol, polyacrylamide and starch are used.

DESCRIPTION OF SYMBOLS 10 Alkaline secondary battery 11 Single cell element 12 Positive electrode plate 13 Positive electrode active material layer 14a Positive electrode current collector tab 14b Positive electrode current collector plate 14c Positive electrode terminal 16 Negative electrode plate 17 Negative electrode active material layer 18 Negative electrode current collector 18a Negative electrode current collector tab 18b Negative electrode Current collector 18c Negative electrode terminal 20 Liquid retaining member 22 LDH separator 28 Box case 28a Bottom 28b Long side wall 28c Short side wall 28d Lid R rib F Flat part W Weak part C Closed side

Claims (16)

A stacked battery in which a plurality of single battery elements having a structure of an alkaline secondary battery are stacked,
A box-shaped case in which the laminated battery is accommodated in a vertical direction,
An alkaline secondary battery comprising:
The box-shaped case has a bottom portion, a pair of long side wall portions parallel to the laminated battery, a pair of short side wall portions perpendicular to the laminated battery, and a lid portion,
The outer surface of the pair of long side wall portions has a flat surface and a plurality of ribs provided in a ridge-like shape protruding from the flat surface, and the plurality of ribs are provided so as to be separated from each other and parallel to the longitudinal direction. Alkaline secondary battery. The alkaline secondary battery according to claim 1, wherein the box-shaped case is made of resin. The alkaline secondary battery according to claim 1 or 2, wherein the rib is provided such that a width of the rib gradually or gradually increases in a direction from the bottom portion toward the lid portion. The pair of long side wall portions has a tapered cross-sectional shape in which a distance between inner walls of the pair of long side wall portions gradually or gradually decreases in a direction from the lid portion to the bottom portion. Item 4. The alkaline secondary battery according to Item 3. The alkaline secondary battery according to claim 1, wherein the rib has a trapezoidal cross-sectional shape. The alkaline secondary battery according to any one of claims 1 to 5, wherein the alkaline secondary battery further includes a positive electrode terminal and a negative electrode terminal, and the positive electrode terminal and the negative electrode terminal are extended from the lid portion. The short side wall portion has a weakened portion whose thickness is locally reduced as compared with other portions of the short side wall portion, and/or the lid portion is thicker than other portions of the lid portion. The alkaline secondary battery according to claim 1, wherein the alkaline secondary battery has a locally reduced fragile portion. The alkaline secondary battery according to claim 1, wherein the rib has a height of 1.0 to 10 mm with respect to the flat portion. The alkaline secondary battery according to any one of claims 1 to 8, wherein the number of the ribs per one longitudinal side wall portion is 5 to 11. The distance between the rib closest to the left end of the long side wall portion and the rib closest to the left end of the long side wall portion, and the distance between the rib closest to the right end of the long side wall portion and the rib closest to the right end of the long side wall portion are the long sides. The alkaline secondary battery according to claim 9, which is narrower than an interval between other ribs that are separated from both ends of the side wall portion. The alkaline secondary battery according to claim 1, wherein the alkaline secondary battery is a zinc secondary battery. The unit cell element is
A positive electrode plate including a positive electrode active material layer,
A negative electrode plate including a negative electrode active material layer containing at least one selected from the group consisting of zinc, zinc oxide, a zinc alloy, and a zinc compound;
LDH separator containing layered double hydroxide (LDH),
Electrolyte and
The alkaline secondary battery according to claim 11, further comprising: a separator, and the positive electrode active material layer and the negative electrode active material layer are isolated from each other via the LDH separator. The LDH separator comprises LDH and a porous substrate, and the LDH closes the pores of the porous substrate so that the LDH separator exhibits hydroxide ion conductivity and gas impermeability. 12. The alkaline secondary battery according to 12. The alkaline secondary battery according to claim 13, wherein the positive electrode active material layer contains nickel hydroxide and/or nickel oxyhydroxide, whereby the zinc secondary battery forms a nickel-zinc secondary battery. An alkaline secondary battery module comprising a plurality of alkaline secondary batteries according to claim 1.
The plurality of alkaline secondary batteries, the long side wall portions are opposed to each other, and are arranged so that the ribs contact each other, thereby forming a spacer by contacting the ribs of the adjacent box-shaped case, As a result, an alkaline secondary battery module that forms vertical ventilation holes. Pressurizing means for pressurizing the longitudinal side wall portion in the thickness direction is provided on the outside of the battery module, whereby the box-shaped case is pressed by the pressing means and bends to apply the single cell element. The alkaline secondary battery module according to claim 15, which is pressed.

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