JP2018186069A - Separator and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a separator which enables the smooth supply of an electrolyte solution to an electrode smoothly; and a secondary battery having the separator.SOLUTION: A separator 2 is to be disposed between a positive electrode and a negative electrode in a secondary battery. The separator 2 comprises an electrolyte solution flow path 21 having an outer periphery opening 211 which opens in its outer peripheral edge, a positive electrode-side opening 212 which opens in a positive electrode-side face, a negative electrode-side opening 214 which opens in a negative electrode-side face, and a connection flow path part 213 for communication between the openings 212 and 214. The positive electrode-side opening 212, the negative electrode-side opening 214, and the connection flow path part 213 are disposed so as to avoid forming a through-hole extending through the separator 2 in a plan view when viewed from a side where the positive electrode is to be disposed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a separator and a secondary battery including the separator.

  Secondary batteries such as alkaline storage batteries and lithium ion secondary batteries are used in batteries for vehicles such as forklifts, hybrid cars, and electric cars. This type of secondary battery has an electrode winding body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, or an electrode assembly in which a plurality of positive electrodes and negative electrodes are stacked with a separator interposed therebetween. Moreover, porous materials, such as a nonwoven fabric and a microporous film, are used as a separator, and electrolyte solution is hold | maintained in the hole of a separator. The separator is disposed in close contact with the electrode so that the electrolytic solution held therein can be quickly supplied to the electrode (for example, Patent Document 1 and Patent Document 2).

JP-A-2-72564 JP 2004-207253 A

  In secondary batteries such as alkaline storage batteries and lithium ion secondary batteries, the positive electrode contracts and the negative electrode expands during charging. Since the amount of contraction of the positive electrode at this time is not exactly the same as the amount of expansion of the negative electrode, the distance between the electrodes in the stacking direction of the electrode assembly varies depending on the charging rate. In addition, during discharging, the positive electrode expands and the negative electrode contracts, contrary to charging. Since the amount of expansion of the positive electrode at this time is not exactly the same as the amount of contraction of the negative electrode, the distance between the electrodes in the stacking direction of the electrode assembly varies according to the charging rate, as in charging.

  When the distance between electrodes becomes narrow during charging / discharging, the separator arrange | positioned between electrodes is compressed. At this time, the electrolytic solution held in the separator is pushed out of the electrode assembly via the outer peripheral edge of the separator that is separated from the electrode. On the other hand, when the distance between the electrodes is increased, the thickness of the separator is restored as the distance between the electrodes increases. And with the restoration | restoration of the thickness of a separator, the electrolyte solution extruded from the separator is absorbed in a separator.

  At this time, the electrolytic solution present outside the separator is absorbed from the outer peripheral edge of the separator and moves to the inside of the separator through the hole of the separator. For this reason, a portion having a relatively large distance from the outer peripheral edge in the separator requires a longer time for the electrolytic solution to reach than a portion having a relatively small distance. Moreover, depending on the case, the part which does not have electrolyte solution arises locally in a separator, and there exists a possibility of causing the increase in internal resistance.

  Further, when the secondary battery is charged and discharged, gas may be generated from the electrode. When this gas stays between the electrode and the separator, a portion where the electrolyte does not exist locally is generated in the separator, which may increase the internal resistance.

  The present invention has been made in view of such a background, and can smoothly supply an electrolytic solution to an electrode during charging and discharging, and can promote the release of gas to the outside of the electrode assembly. And a secondary battery including the separator.

One aspect of the present invention is a separator interposed between a positive electrode and a negative electrode in a secondary battery,
An outer peripheral opening that opens on the side peripheral surface, a positive electrode opening that opens on the positive electrode surface, a negative electrode opening that opens on the negative electrode surface, and a connection channel that connects the openings to each other An electrolyte flow path with a portion,
The positive electrode side opening, the negative electrode side opening, and the connection channel portion are arranged so that a through hole penetrating the separator is not formed in a plan view as viewed from the side where the positive electrode is arranged. In the separator.

Another aspect of the present invention is a secondary battery comprising the separator according to the above aspect,
A positive electrode;
The separator laminated on the positive electrode;
A negative electrode laminated on the separator;
Having one or more single cells provided with an electrolytic solution interposed between the positive electrode and the negative electrode;
In the secondary battery, the outer peripheral opening of the separator is spaced apart from the positive electrode and the negative electrode.

  The separator has an electrolyte flow path including an outer peripheral opening, a positive electrode side opening, and a negative electrode side opening. Moreover, these opening parts are in a communication state via a connection flow-path part. By interposing the separator between the positive electrode and the negative electrode in the secondary battery, the electrolyte in the electrolyte channel is smoothly moved during charging / discharging, and the gas generated from the electrode during charging / discharging is dissolved in the electrolyte. The gas can be circulated in the flow path to facilitate the release of gas from the inside of the electrode assembly to the outside.

  That is, when the separator is compressed during charging and discharging, excess electrolytic solution present in the separator is pushed out from the outer peripheral edge of the separator to the outside like the conventional separator. Furthermore, the separator can move the electrolyte in the electrolyte channel toward the outer peripheral opening of the separator via the connection channel. As a result, the electrolytic solution can be pushed out of the separator from both the outer peripheral edge of the separator and the outer peripheral opening.

  Further, when the thickness of the separator is restored, the electrolyte present outside the separator is absorbed from the outer peripheral edge of the separator into the separator, as in the case of the conventional separator. Furthermore, the separator can suck the electrolyte into the electrolyte flow path from the outer peripheral opening. And the electrolyte solution in an electrolyte flow path can be moved toward a positive electrode side opening part or a negative electrode side opening part via a connection flow path part, and can be supplied to a positive electrode and a negative electrode. As a result, the electrolytic solution can be absorbed from both the outer peripheral edge of the separator and the outer peripheral opening, and the electrolytic solution can be supplied to the positive electrode and the negative electrode.

  Thus, by providing the separator having the electrolyte flow path between the positive electrode and the negative electrode, the electrolyte can be moved from the outside of the separator to the inside, and the electrolyte can be moved from the inside of the separator to the outside. It can be done smoothly.

  In addition, the positive electrode side opening, the negative electrode side opening, and the connection flow path are arranged so that a through hole penetrating the separator is not formed in a plan view as viewed from the side where the positive electrode is arranged. That is, when the separator is disposed between the positive electrode and the negative electrode, the separator exists on the entire surface between the positive electrode and the negative electrode, and the positive electrode and the negative electrode do not directly face each other through the through hole. Has been. Therefore, the separator can smoothly move the electrolytic solution while ensuring electrical insulation between the positive electrode and the negative electrode.

  Furthermore, in the positive electrode side opening, a relatively large gap is formed between the surface of the positive electrode and the surface of the separator. Similarly, in the negative electrode side opening, a relatively large gap is formed between the surface of the negative electrode and the separator. Therefore, the gas generated from the positive electrode or the negative electrode at the time of charging / discharging can be circulated in the electrolyte channel through the positive electrode side opening and the negative electrode side opening. And gas can be discharge | released to the exterior of an electrode assembly from an outer peripheral opening part.

  As described above, the separator smoothly supplies the electrolytic solution to the electrode during charging and discharging, and distributes the gas generated from the positive electrode and the negative electrode during charging and discharging into the electrolytic solution flow path, thereby providing an electrode assembly. The release of gas from the inside to the outside can be promoted.

  The secondary battery includes one or more single cells in which the positive electrode, the separator of the above-described aspect, and the negative electrode are sequentially stacked. Thereby, when a separator is compressed at the time of charging / discharging, electrolyte solution can be extruded to the exterior of a separator from both the outer periphery part of a separator, and an outer peripheral opening part. Further, when the thickness of the separator is restored, the electrolytic solution can be absorbed from both the outer peripheral edge portion of the separator and the outer peripheral opening portion. As a result, the secondary battery can suppress an increase in internal resistance due to a delay in the supply of the electrolytic solution.

3 is a cross-sectional view showing the main parts of a secondary battery in Example 1. FIG. It is the top view which looked at the separator in Example 1 from the positive electrode side. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. 2 is an exploded perspective view of a separator in Example 1. FIG. In Example 2, it is a top view of the separator which has a 3 layer structure and each layer has continued in the lamination order. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. 6 is a development view of a separator in Example 2. In Example 3, it is a top view of the separator provided with the some positive electrode side opening part and the negative electrode side opening part. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. FIG. 9 is a cross-sectional view taken along line X-X in FIG. 8. FIG. 6 is a development view of a separator in Example 3. It is a disassembled perspective view of the test body 1 in an experiment example. It is a top view of the positive electrode in the test body 2 of an experiment example. It is a top view of the negative electrode in the test body 2 of an experiment example. It is a top view of the positive electrode in the test body 3 of an experiment example. It is a top view of the negative electrode in the test body 3 of an experiment example. In Example 4, it is a top view of the separator with which the width | variety of the electrolyte flow path is so wide that it is near the outer periphery opening part. 10 is a perspective view of a secondary battery in Example 5. FIG. FIG. 19 is an enlarged plan view of a liquid injection port in FIG. 18. FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. 19. FIG. 21 is a cross-sectional view taken along line XXI-XXI in FIG. 20.

  The separator is interposed between the positive electrode and the negative electrode in the secondary battery. The separator can be appropriately selected from known separators according to the configuration of the secondary battery. For example, when the secondary battery is configured as an alkaline storage battery, a known separator for an alkaline storage battery, such as a nonwoven fabric having a hydrophilic functional group, can be used. As resin which comprises this nonwoven fabric, polyolefin resin, such as polyethylene, a polypropylene, an ethylene propylene copolymer, can be employ | adopted, for example. In addition, when the secondary battery is configured as a lithium ion secondary battery, a known separator for a lithium ion secondary battery such as a microporous film of a polyolefin resin can be used.

  The electrolyte flow path provided in the separator includes an outer peripheral opening that opens on the side peripheral surface of the separator, a positive electrode opening that opens on the positive electrode surface, and a negative electrode opening that opens on the negative electrode surface. These openings are in communication with each other via a connection channel. The arrangement and shape of the electrolyte channel can take various forms. For example, the separator may have one electrolyte flow path provided with an outer peripheral opening, a positive electrode side opening, and a negative electrode side opening, or may have two or more electrolyte flow paths. Good.

  The positive electrode side opening, the negative electrode side opening, and the connection channel portion are arranged so that a through hole penetrating the separator is not formed in a plan view as viewed from the side where the positive electrode is arranged. When the through hole is formed in the separator in a plan view as viewed from the side where the positive electrode is disposed, the positive electrode and the negative electrode directly face each other through the through hole.

  In order to avoid such a situation, for example, the positive electrode side opening may be arranged at a position different from the negative electrode side opening in a plan view as viewed from the side where the positive electrode is arranged. In this case, formation of the through hole in the separator can be avoided more easily. Moreover, the freedom degree of arrangement | positioning of a connection flow-path part can be raised more.

  The opening on the positive electrode side can take various shapes such as an elongated slit shape, a square shape, and a circular shape in a plan view as viewed from the side where the positive electrode is disposed. The number of positive electrode side openings provided in one electrolyte channel may be one, or two or more. Similarly to the positive electrode side opening, the negative electrode side opening can take various shapes such as an elongated slit shape, a square shape, and a circular shape when viewed from the side where the negative electrode is disposed. Further, the number of the negative electrode side openings provided in one electrolyte flow path may be one, or two or more.

  The connection flow path portion may have a straight line shape that connects the openings in a plan view as viewed from the side where the positive electrode is disposed, or branches such as a Y shape, an H shape, and an X shape. The shape which it has may be exhibited. Moreover, the cross-sectional shape of the connection flow path portion can take various shapes such as a square shape and a circular shape.

  The separator may have a single layer structure composed of a single nonwoven fabric or microporous film, or may have a multilayer structure in which two or more nonwoven fabrics or microporous films are laminated. By making a separator into a single layer structure, the increase in the use area of the nonwoven fabric used as a raw material of a separator or a microporous film can be suppressed compared with the separator of a multilayer structure. As a result, an increase in the material cost of the separator can be suppressed.

  A separator having a multilayer structure uses a larger area of material than a separator having a single layer structure, but can achieve the same function as a separator having a single layer structure. For example, the separator includes a positive electrode side layer having a positive electrode side opening, a negative electrode side layer having a negative electrode side opening, and a connection flow path portion, and is interposed between the positive electrode side layer and the negative electrode side layer. It has a multilayer structure including an intermediate layer equal to or more than one layer, and at least one of the layers constituting the multilayer structure may have an outer peripheral opening. In this case, after preparing the positive electrode side layer, the intermediate layer, and the negative electrode side layer separately, the outer peripheral opening, the positive electrode side opening, and the negative electrode side opening are communicated with each other by a simple operation of laminating them. A liquid flow path can be formed easily.

  When a separator has a multilayer structure, it is preferable that each layer which comprises a multilayer structure is continued. In this case, the electrolyte channel is formed in a state where the separator is expanded, and then the separator is folded and the positive electrode side layer, the intermediate layer, and the negative electrode side layer are sequentially laminated to facilitate the electrolyte channel. Can be formed.

  The separator is disposed between the positive electrode and the negative electrode in the secondary battery. The secondary battery has one or more single cells each including a positive electrode, a separator laminated on the positive electrode, and a negative electrode laminated on the separator. As the positive electrode, for example, a foil electrode in which a positive electrode active material layer is disposed on one or both sides of a metal foil as a current collector, or a porous material in which a positive electrode active material is held in a metal porous body as a current collector An electrode or the like can be employed. Moreover, as a negative electrode, the porous electrode by which the negative electrode active material was hold | maintained in the foil electrode by which the negative electrode active material layer was arrange | positioned on the one or both surfaces of the metal foil as a collector, or the metal porous body as a collector An electrode or the like can be employed.

  In addition, a bipolar electrode having a metal foil as a current collector, a positive electrode active material layer disposed on the front side surface of the metal foil, and a negative electrode active material layer disposed on the back side surface is used as the electrode. You can also. In this case, bipolar electrodes and separators are alternately stacked, and a positive electrode active material layer as a positive electrode and a negative electrode active material layer as a negative electrode face each other with a separator interposed therebetween, so that a single foil is provided between metal foils. A cell can be configured.

  When bipolar electrodes are used, as described above, a plurality of single cells can be connected in series with a simple configuration in which bipolar electrodes and separators are alternately stacked. As a result, the electromotive force of the secondary battery can be further increased.

  In addition, when bipolar electrodes are used, the number of single cells can be increased with respect to the total number of electrodes, compared with the case where unipolar electrodes are used. Therefore, when the total number of electrodes is the same, the number of single cells can be increased as compared with the case where unipolar electrodes are used. Further, when the number of single cells is the same, the total number of electrodes can be reduced and the size of the secondary battery in the stacking direction can be further reduced as compared with the case where unipolar electrodes are used.

  At least one of the positive electrode and the negative electrode may have a groove portion that communicates with the electrolyte flow path of the separator and that is open on the side peripheral surface of the electrode. In this case, at the time of charging / discharging, the electrolytic solution can be moved from the electrolytic solution flow channel to the groove portion, or can be moved from the groove portion to the electrolytic solution flow channel. As a result, the electrolyte solution can be supplied to each part of the separator and the electrode more quickly and smoothly.

  The number of grooves, width, depth, cross-sectional shape, arrangement in a plan view when viewed from the thickness direction of the electrodes, and the like can be set in various modes according to desired characteristics. For example, the number of grooves may be one, or may be two or more. The width of the groove portion may be constant over the entire length, or the width may vary depending on the position of the groove portion. The depth of the groove may be shallower than the thickness of the electrode. For example, when a foil electrode is used, the bottom of the groove may reach the metal foil, or the bottom of the groove may remain in the active material layer.

  The cross-sectional shape of the groove portion can be various forms such as a square shape, a rectangular shape, a V shape, a U shape, and a semicircular shape. Further, the groove portion may extend linearly in a plan view viewed from the thickness direction of the electrode, or may have a curved shape. In the case of having two or more groove portions, the groove portions can be crossed with each other.

  The secondary battery includes a case that accommodates a positive electrode, a separator, and a negative electrode, and a liquid injection port that penetrates the case and injects an electrolytic solution into the case. It may be arranged at a position facing the mouth. In the assembly operation of the secondary battery, usually, after arranging the positive electrode, the negative electrode, and the separator in the case, the electrolytic solution is injected into the case from the liquid inlet, and the separator is impregnated with the electrolytic solution. At this time, by disposing the outer peripheral opening at a position facing the liquid injection port, the electrolyte injected from the liquid injection port can easily flow into the electrolyte flow path of the separator. And by making electrolyte solution flow in into an electrolyte solution flow path, while making a separator impregnate electrolyte solution rapidly, generation | occurrence | production of the part which is not impregnated with electrolyte solution can be suppressed more effectively.

  Further, the secondary battery includes a case that accommodates the positive electrode, the separator, and the negative electrode, and a pressure release valve that is disposed on the case and discharges gas from the inside of the case to the outside of the case. The opening may be arranged at a position facing the pressure release valve. The pressure release valve is closed during normal use, and is configured to be opened when the pressure in the case becomes excessively high.

  When the outer peripheral opening is disposed at a position facing the pressure release valve, the gas generated from the electrode during charge / discharge easily moves in the electrolyte flow path and reaches the front of the pressure release valve. Therefore, as the amount of gas increases, the electrolyte can be removed from around the pressure release valve. As a result, when the pressure in the case becomes excessively high and the pressure release valve is opened, the amount of the electrolyte discharged from the pressure release valve can be further reduced.

The secondary battery may be configured as a nickel hydride storage battery. The reaction at the time of charge in each electrode of the nickel metal hydride storage battery is represented by the following half reaction formulas (1) to (2). In the following formulas (1) to (2), M is a hydrogen storage alloy as a negative electrode active material.
Positive electrode: Ni (OH) ₂ + OH ⁻ → NiOOH + H ₂ O + e ⁻ (1)
Negative electrode: M + H ₂ O + e ⁻ → MH + OH ⁻ (2)

Moreover, the reaction at the time of discharge in each electrode of a nickel metal hydride storage battery is represented by the following half reaction formulas (3) to (4).
Positive electrode: NiOOH + H ₂ O + e ⁻ → Ni (OH) ₂ + OH ⁻ (3)
Negative electrode: MH + OH ⁻ → M + H ₂ O + e ⁻ (4)

Thus, the nickel-metal hydride storage battery requires water (H ₂ O) or hydroxide ions (OH ⁻ ) for electrode reaction both during charging and during discharging. Therefore, if a delay in the supply of the electrolyte to each electrode occurs, the internal resistance of the nickel-metal hydride storage battery tends to increase. On the other hand, according to the said separator, since electrolyte solution can be smoothly supplied to each electrode, the increase in the internal resistance of a nickel hydride storage battery can be suppressed effectively. Therefore, the separator is suitable for a nickel metal hydride storage battery.

The secondary battery may be configured as a lithium ion secondary battery. For example, the reaction at the time of charging in each electrode of a lithium ion secondary battery when LiCoO ₂ is used as the positive electrode active material and graphite is used as the negative electrode active material is expressed by the following half reaction formulas (5) to (6). . In addition, the value of x in the following formulas (5) to (6) is greater than 0 and equal to or less than 1.
Positive electrode: LiCoO ₂ → Li _(1-x) CoO ₂ + xLi ⁺ + xe ⁻ (5)
Negative electrode: C + xLi ⁺ + xe ⁻ → CL _x (6)

Moreover, the reaction at the time of discharge in each electrode of a lithium ion secondary battery is represented by the following half reaction formulas (7) to (8).
Positive electrode: Li _(1-x) CoO ₂ + xLi ⁺ + xe ⁻ → LiCoO ₂ (7)
Negative electrode: CLi _x → C + xLi ⁺ + xe ⁻ (8)

In lithium ion secondary batteries, Li ⁺ in the electrolyte moves between the positive and negative electrodes in a solvated state with solvent molecules that do not directly contribute to the charge / discharge reaction in the electrolyte, both during charging and discharging. Therefore, Li ⁺ and a solvent in the electrolytic solution are required. Therefore, when a delay in the supply of the electrolyte to each electrode occurs, the internal resistance of the lithium ion secondary battery tends to increase. On the other hand, according to the said separator, since electrolyte solution can be smoothly supplied to each electrode, the increase in the internal resistance of a lithium ion secondary battery can be suppressed effectively. Therefore, the separator is suitable for a lithium ion secondary battery.

(Example 1)
Examples of the separator and a secondary battery including the separator will be described with reference to the drawings. As shown in FIG. 1, the secondary battery 1 of this example includes a positive electrode P, a separator 2 stacked on the positive electrode P, a negative electrode N stacked on the separator 2, and a positive electrode P and a negative electrode N. And one or more single cells C having an electrolyte solution (not shown) interposed therebetween. As shown in FIGS. 2 to 4, the separator 2 has an outer peripheral opening 211 opened on the side circumferential surface thereof, a positive electrode side opening 212 opened on the positive electrode P side surface, and an opening on the negative electrode N side surface. It has the electrolyte flow path 21 provided with the negative electrode side opening part 214 and the connection flow path part 213 which makes the opening parts 212 and 214 communicate.

  In addition, as shown in FIG. 2, in a plan view as viewed from the side where the positive electrode P is disposed, the positive electrode side opening 212, the negative electrode side opening 214, and the connection flow path portion 213 have through holes penetrating the separator 2. It arrange | positions so that it may not form. In FIG. 1, the structure of the separator 2 is simplified for convenience.

  In the secondary battery 1 of this example, as shown in FIG. 1, an electrode assembly 11 in which a plurality of electrodes 31 and 32 are stacked via a separator 2 and an end of the electrode assembly 11 in the stacking direction are respectively applied. A restraining member 12 that contacts and restrains the electrode assembly 11 and a sealing material 13 that covers a side peripheral surface of the electrode assembly 11 are provided. The electrode assembly 11 includes termination electrodes 31 disposed at both ends in the stacking direction, and a plurality of bipolar electrodes 32 disposed between the termination electrodes 31. The separator 2 is disposed between the adjacent electrodes 31 and 32.

  The bipolar electrode 32 includes a rectangular metal foil 33, a positive electrode active material layer 34 p provided on the front side surface of the metal foil 33, and a negative electrode active material layer 34 n provided on the back side surface. The positive electrode active material layer 34 p is provided on the front side surface of the metal foil 33 in a region inside the peripheral portion 331 of the metal foil 33. Similarly to the positive electrode active material layer 34p, the negative electrode active material layer 34n is provided in a region inside the peripheral portion 331 of the metal foil 33 on the back side surface of the metal foil 33.

  Of the two termination electrodes 31 (31p, 31n), the first termination electrode 31p disposed at one end in the stacking direction has the same configuration as the bipolar electrode 32 except that it does not have the negative electrode active material layer 34n. ing. The second termination electrode 31n disposed at the other end in the stacking direction has the same configuration as the bipolar electrode 32 except that it does not have the positive electrode active material layer 34p.

  These electrodes 31 and 32 are arranged such that the positive electrode active material layer 34p as the positive electrode P and the negative electrode active material layer 34n as the negative electrode N are alternately arranged in the stacking direction. Further, the separator 2 is interposed between the positive electrode active material layer 34p and the negative electrode active material layer 34n. Thus, a single cell C in which the positive electrode active material layer 34p and the negative electrode active material layer 34n face each other via the separator 2 is configured between the metal foils 33. Further, in the electrode assembly 11 of this example, the plurality of single cells C are electrically connected in series via the metal foil 33.

  Metal restraining members 12 are disposed at both ends of the electrode assembly 11 in the stacking direction. The restraining member 12 is held by a holding plate (not shown) in contact with the metal foil 33 of the terminal electrode 31. The electrode assembly 11 of this example can be electrically connected to an external circuit via the restraining member 12.

  A side peripheral surface of the electrode assembly 11 is covered with a sealing material 13. Further, the sealing material 13 holds the peripheral portion 331 of the metal foil 33 in each of the electrodes 31 and 32, that is, the portion where the active material layers 34p and 34n are not provided.

  As shown in FIG. 2, the separator 2 of this example has a rectangular shape larger than the negative electrode active material layer 34n in a plan view, and the outer peripheral edge of the separator 2 has a positive electrode active material layer 34p and a negative electrode active material layer 34n. Than the outside. Moreover, the separator 2 has one electrolyte flow path 21 extending in a direction parallel to the short side. The electrolyte channel 21 is arranged so as to divide the separator 2 into two equal parts.

  As shown in FIGS. 3 and 4, the separator 2 of this example includes a positive electrode side layer 22 having a positive electrode side opening 212, a negative electrode side layer 24 having a negative electrode side opening 214, and a connection flow path portion 213. And a three-layer structure including a single intermediate layer 23 interposed between the positive electrode side layer 22 and the negative electrode side layer 24. As shown in FIGS. 2 to 4, the positive electrode side opening 212 is disposed at one end of the electrolyte flow path 21, and has an elongated slit shape extending in a direction parallel to the short side of the separator 2. Yes.

  The positive electrode side opening 212 extends to the side peripheral surface of the separator 2. The positive electrode side opening 212 in this example is also opened on the side peripheral surface of the separator 2, and also serves as the outer peripheral opening 211. Further, a portion of the positive electrode side opening 212 extending outward from the positive electrode active material layer 34 p is an excess space of the single cell C, that is, a space formed between the sealing material 13 and the electrode assembly 11. And has the same function as the outer peripheral opening 211.

  As shown in FIGS. 2 to 4, the negative electrode side opening 214 is disposed at the other end of the electrolyte flow path 21, and has an elongated slit shape extending in a direction parallel to the short side of the separator 2. Yes. The negative electrode side opening 214 extends to the side peripheral surface of the separator 2. In addition, the negative electrode side opening 214 of this example is also opened on the side peripheral surface of the separator 2 and also serves as the outer peripheral opening 211. Further, a portion of the negative electrode side opening 214 that extends outward from the negative electrode active material layer 34 n is open to an excess space of the single cell C, and has the same function as the outer peripheral opening 211. . Moreover, the separator 2 of this example has the outer periphery opening part 211 in the positive electrode side layer 22 and the negative electrode side layer 24 among 3 layer structures.

  Further, as shown in FIG. 3, the connection flow path portion 213 extends in a direction parallel to the short side of the separator 2. The connection flow path part 213 communicates with the positive electrode side opening 212 at one end in the longitudinal direction and communicates with the negative electrode side opening 214 at the other end. Thus, the positive electrode side opening 212 of this example communicates with the connection flow path part 213 at a position different from the negative electrode side opening 214. Therefore, the separator 2 does not have a through hole penetrating the separator 2 in a plan view as viewed from the side where the positive electrode P is disposed.

  The effect of this example is demonstrated. The separator 2 includes a positive electrode side opening 212 that also serves as the outer peripheral opening 211 and a negative electrode side opening 214 that also serves as the outer peripheral opening 211, and the openings 212 and 214 are connected to each other via the connection flow path part 213. Communicate.

  Therefore, when the separator 2 is compressed at the time of charging / discharging, excess electrolytic solution existing in the separator 2 is pushed out from the outer peripheral edge portion of the separator 2 to the outside of the separator 2 as in the conventional separator. Furthermore, the separator 2 can move the electrolytic solution in the electrolytic solution flow channel 21 toward the outer peripheral opening 211 of the separator 2 via the connection flow channel portion 213. As a result, the electrolytic solution can be pushed out of the separator 2 from both the outer peripheral edge of the separator 2 and the outer peripheral opening 211.

  Further, when the thickness of the separator 2 is restored, the electrolyte present outside the separator 2 is absorbed from the outer peripheral edge of the separator 2 into the separator, as in the conventional separator. Further, the separator 2 can suck the electrolyte into the electrolyte channel 21 from the outer peripheral opening 211. Then, the electrolyte solution in the electrolyte channel 21 is moved toward the positive electrode side opening 212 and the negative electrode side opening 214 via the connection channel part 213, and is moved to the positive electrode active material layer 34 p and the negative electrode active material layer 34 n. Can be supplied. As a result, the electrolytic solution can be absorbed from both the outer peripheral edge of the separator 2 and the outer peripheral opening 211, and the electrolytic solution can be supplied to the positive electrode active material layer 34p and the negative electrode active material layer 34n.

  Thus, by providing the separator 2 provided with the electrolytic solution flow channel 21 between the positive electrode active material layer 34p and the negative electrode active material layer 34n, the electrolytic solution is circulated in the electrolytic solution flow channel 21 during charging and discharging. It is possible to smoothly move the electrolytic solution from the outside to the inside of the separator 2 and to move the electrolytic solution from the inside to the outside of the separator 2.

  Furthermore, in the positive electrode side opening 212 and the negative electrode side opening 214, a relatively large gap is formed between the separator 2 and the metal foil 33 as the current collector. Therefore, the gas generated from the positive electrode active material layer 34p or the negative electrode active material layer 34n at the time of charging / discharging can be circulated in the electrolyte channel 21 through the positive electrode side opening 212 and the negative electrode side opening 214. Then, gas can be discharged from the outer peripheral opening 211 to the outside of the electrode assembly 11.

  Moreover, the positive electrode side opening 212, the negative electrode side opening 214, and the connection flow path part 213 are arranged so as not to form a through hole penetrating the separator 2 in a plan view as viewed from the side where the positive electrode P is arranged. Yes. Therefore, it is possible to prevent the positive electrode P and the negative electrode N from directly facing each other through the through hole. As a result, the separator 2 can smoothly move the electrolytic solution while ensuring electrical insulation between the positive electrode P and the negative electrode N.

  As described above, the separator 2 smoothly supplies the electrolyte solution to the positive electrode P and the negative electrode N at the time of charge / discharge, and also discharges the gas generated from the positive electrode P and the negative electrode N at the time of charge / discharge to the electrolyte channel 21. It is possible to promote the release of gas from the inside of the electrode assembly 11 to the outside.

  The secondary battery 1 of this example has one or more single cells C in which a positive electrode P, a separator 2 and a negative electrode N are sequentially stacked. Further, the separator 2 is arranged such that the outer peripheral opening 211 is separated from the positive electrode P and the negative electrode N. Thereby, when the separator 2 is compressed during charging and discharging, the electrolyte solution can be pushed out of the separator 2 from both the outer peripheral edge portion of the separator 2 and the outer peripheral opening portion 211. Further, when the thickness of the separator 2 is restored, the electrolytic solution can be absorbed from both the outer peripheral edge portion of the separator 2 and the outer peripheral opening portion 211. As a result, the secondary battery 1 can suppress an increase in internal resistance due to a delay in supply of the electrolytic solution.

  The positive electrode side opening 212 of the separator 2 of this example is arranged at a position different from the negative electrode side opening 214 in a plan view as viewed from the side where the positive electrode P is arranged. Therefore, the separator 2 of this example can further increase the degree of freedom of the arrangement of the connection flow path portion 213.

  Further, the separator 2 of this example includes a positive electrode side layer 22 provided with a positive electrode side opening 212, a negative electrode side layer 24 provided with a negative electrode side opening 214, and a connection flow path part 213, It has a multilayer structure including one or more intermediate layers 23 interposed between the negative electrode side layer 24, and at least one of the layers constituting the multilayer structure has an outer peripheral opening 211. Yes. Therefore, after preparing the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 separately, the outer peripheral opening 211, the positive electrode side opening 212, and the negative electrode side opening 214 are communicated with each other by a simple operation of stacking them. Thus, the electrolyte channel 21 can be easily formed.

  Moreover, the positive electrode side opening 212 extends outward from the positive electrode active material layer 34p as the positive electrode P. Similarly, the negative electrode side opening 214 extends outward from the negative electrode active material layer 34n as the negative electrode N. A portion extending outward from the positive electrode active material layer 34p in the positive electrode side opening 212 and a portion extending outward from the negative electrode active material layer 34n in the negative electrode side opening 214 are in the surplus space of the single cell C. Since it is open, it has the same function as the outer peripheral opening 211.

  That is, when the separator 2 is compressed during charging / discharging, in addition to the outer peripheral edge and the outer peripheral opening 211 of the separator 2, the excess space of the single cell C in the positive electrode side opening 212 and the negative electrode side opening 214 is provided. The electrolytic solution can be pushed out from the opened portion. Further, when the thickness of the separator 2 is restored at the time of charging / discharging, in addition to the outer peripheral edge portion and the outer peripheral opening portion 211 of the separator 2, the excess space of the single cell C in the positive electrode side opening portion 212 and the negative electrode side opening portion 214. The electrolyte solution can also be absorbed from the portion opened to the surface. Therefore, the secondary battery 1 of this example can more effectively suppress an increase in internal resistance due to a delay in the supply of the electrolyte.

(Example 2)
This example is an example of the separator 202 in which the layers 22, 23, and 24 constituting the multilayer structure are connected. Of the reference numerals used in and after the present embodiment, the same reference numerals as those used in the above-described embodiments represent the same constituent elements as those in the above-described embodiments unless otherwise specified.

  As shown in FIGS. 5 and 6, the separator 202 of this example has a three-layer structure including the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24, and the positive electrode is disposed. It has a rectangular shape when viewed from the side. The positive electrode side layer 22 continues to the intermediate layer 23 via a folded portion 202a formed along one long side of the separator 202 in plan view. The intermediate layer 23 is connected to the negative electrode side layer 24 via a folded portion 202b formed along the other long side of the separator 202 in plan view. Thus, the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 of this example are connected in the stacking order via the folded portions 202a and 202b.

  As shown in FIG. 7, the separator 202 of this example has a rectangular shape in which the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 are connected in this order in the unfolded state. Further, the separator 202 has an electrolyte flow path 25 extending from the positive electrode side layer 22 to the negative electrode side layer 24 along a diagonal line in a developed state.

  When the separator 202 is folded at the folded portions 202a and 202b and the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 are laminated, the portion of the electrolyte channel 25 provided in the positive electrode side layer 22 is the positive electrode side opening. 252. As shown in FIG. 5, the positive electrode side opening 252 extends obliquely with respect to the short side of the separator 202 from the folded portion 202 a. In addition, a portion of the electrolyte channel 25 provided in the negative electrode side layer 24 becomes a negative electrode side opening 254. The negative electrode side opening 254 extends in an oblique direction with respect to the short side of the separator 202 from the folded portion 202b.

  A portion of the electrolyte flow path 25 provided in the intermediate layer 23 becomes a connection flow path portion 253. The connection flow path portion 253 has a linear shape connecting the end portion on the folded portion 202a side in the positive electrode side opening portion 252 and the end portion on the folded portion 202b side in the negative electrode side opening portion 254. Further, the connection flow path portion 253 communicates with the positive electrode side opening 252 at one end in the longitudinal direction, and communicates with the negative electrode side opening 254 at the other end. Therefore, the separator 202 does not have a through hole penetrating the separator 202 in a plan view as viewed from the side where the positive electrode P is disposed.

  Further, as shown in FIG. 6, an outer peripheral opening 251 that opens over both the positive electrode side layer 22 and the intermediate layer 23 is formed in the folded portion 202 a between the positive electrode side layer 22 and the intermediate layer 23. Similarly, an outer peripheral opening 251 that opens over both the negative electrode side layer 24 and the intermediate layer 23 is formed in the folded portion 202b between the intermediate layer 23 and the negative electrode side layer 24. Others are the same as in the first embodiment.

  The separator 202 of this example has a three-layer structure, and each layer constituting the three-layer structure is continuous in the stacking order. Therefore, after forming the electrolyte flow path 25 in a state where the separator 202 is expanded, the separator 202 is folded and the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 are laminated, thereby the electrolyte flow path. 25 can be formed easily. In addition, the separator 202 of this example can achieve the same effects as those of the first embodiment.

Example 3
This example is an example of the separator 203 having the electrolyte flow path 26 provided with a plurality of outer peripheral openings 261, positive electrode side openings 262, and negative electrode side openings 264. As shown in FIG. 8, the separator 203 of this example has a three-layer structure of a positive electrode side layer 22, an intermediate layer 23, and a negative electrode side layer 24. As shown in FIG. 11, the positive electrode side layer 22, the intermediate layer 23, and the negative electrode side layer 24 are connected in the stacking order via the folded portions 203 a and 203 b.

  As shown in FIG. 8, the positive electrode side layer 22 is extended from three positive electrode side openings 262 a extending from one long side 203 c of the separator 203 and one short side 203 e of the separator 203. And two positive electrode side openings 262b. Each of these positive electrode side openings 262a and 262b has an elongated slit shape. Further, the positive electrode side openings 262 a and 262 b are also opened on the side peripheral surface of the separator 203, and also serve as the outer peripheral opening 261.

  The intermediate layer 23 is provided with a connection flow path portion 263 that allows the positive electrode side opening 262 and the negative electrode side opening 264 to communicate with each other. The connection flow path part 263 has an H shape in a plan view as viewed from the side where the positive electrode P is disposed. As shown in FIGS. 8 and 9, one vertical bar portion 263 a of the connection channel portion 263 has three positive electrode side openings extending from the long side 203 c of the separator 203 in the positive electrode side opening portion 262. Crosses the portion 262a. Further, as shown in FIGS. 8 and 10, the horizontal bar portion 263 b of the connection flow path portion 263 has two positive electrode side openings extending from the short side 203 e of the separator 203 in the positive electrode side opening portion 262. Crosses the portion 262b. Thus, the connection flow path part 263 of this example communicates with the five positive electrode side openings 262.

  As shown in FIGS. 8 and 11, the negative electrode side layer 24 extends from three negative electrode side openings 264a extending from the other long side 203d of the separator 203 in plan view and from the other short side 203f. And two negative electrode side openings 264b provided. Each of these negative electrode side openings 264a, 264b has an elongated slit shape. Further, the negative electrode side openings 264 a and 264 b are also opened on the side peripheral surface of the separator 203, and also serve as the outer peripheral opening 261.

  The three negative electrode side openings 264a extending from the long side 203d of the separator 203 in the negative electrode side opening 264 are the other vertical bar portion of the connection channel part 263, as shown in FIGS. It intersects with H.263c. In addition, as shown in FIG. 8, the two negative electrode side openings 264b extending from the short side 203f of the separator 203 intersect the horizontal bar portion 263b of the connection flow path part 263 inside the positive electrode side opening 262b. ing. As described above, the connection flow path portion 263 of this example communicates with the five negative electrode side openings 264.

  In addition, as shown in FIG. 8, the positive opening 262 communicates with the connection channel 263 at a position different from the negative opening 264 in a plan view as viewed from the side where the positive electrode P is disposed. . Therefore, the separator 203 does not have a through hole penetrating the separator 203 in a plan view as viewed from the side where the positive electrode P is disposed. Others are the same as in the second embodiment.

  By providing a plurality of outer peripheral openings 261 as in this example, it is possible to smoothly flow in the electrolyte solution from the outside to the inside of the separator 203 and the electrolyte solution from the inside to the outside of the separator 203. . Further, by providing a plurality of positive electrode side openings 262 and negative electrode side openings 264, the area of these openings can be increased. As a result, the electrolytic solution can be supplied to the positive electrode P and the negative electrode N through the electrolytic solution channel 26 more quickly and smoothly. In addition, the separator 203 of this example can achieve the same effects as those of the second embodiment.

(Experimental example)
This example is an example in which the effect of reducing the internal resistance produced by the electrolyte channel 26 is evaluated. The configuration of the test body used in this example will be described below.

<Test body 1>
As shown in FIG. 12, the test body 1 has a single cell including a first electrode 301p, a second electrode 301n, and a separator 204 interposed therebetween. The first electrode 301p has a metal foil 35 and a positive electrode active material layer 36p as the positive electrode P. The metal foil 35 has a current collector portion 351 having a rectangular shape and a tab portion 352 extending from a corner portion of the current collector portion 351. The positive electrode active material layer 36p is provided on one surface of the current collector portion 351. A more detailed configuration of the first electrode 301p is as follows.

・ Dimension of current collector portion 351 29 mm × 24 mm
・ Composition of positive electrode active material layer 36p β-type nickel hydroxide 90% by mass
Cobalt powder 3% by mass
Binder 5% by mass
Yttrium oxide 1% by mass
Thickener 1% by mass
・ Weight per unit 26mg / cm ²
Density 2.9 g / cm ³
-Metal foil 35 Nickel foil (thickness 20 μm)

  Similar to the first electrode 301p, the second electrode 301n includes a metal foil 35 and a negative electrode active material layer 36n as the negative electrode N. The negative electrode active material layer 36 n is provided on one surface of the current collector portion 351 of the metal foil 35. A more detailed configuration of the second electrode 301n is as follows.

・ Dimensions 31mm × 26mm
-Composition of negative electrode active material layer 36n A2B7 type hydrogen storage alloy 97% by mass
Binder 2% by mass
Thickener 1% by mass
・ Weight per unit 35mg / cm ²
・ Density 5.0 g / cm ³
-Metal foil 35 Nickel foil (thickness 20 μm)

  A separator 204 is disposed between the positive electrode active material layer 36p and the negative electrode active material layer 36n. The separator 204 of this example has the electrolyte flow path 26 having the same shape as that of the third embodiment. A more detailed configuration of the separator 204 is as follows.

・ Material Polyolefin nonwoven fabric ・ Dimensions 36mm × 30mm
・ Thickness 90μm
・ Porosity 50%
・ The width of the electrolyte channel 26 is 1 mm.

  After the second electrode 301n, the separator 204, and the first electrode 301p are stacked in this order to form a single cell, the single cell is accommodated in the case, and the separator is compressed in the stacking direction so that the thickness becomes 70 μm (illustrated). (Omitted). Thereafter, an electrolytic solution composed of a mixed aqueous solution of KOH, NaOH, and LiOH (total concentration 7 M) was injected into the case. The test body 1 was produced by the above.

<Test body 2>
The test body 2 is replaced with the first electrode 301p and the second electrode 301n of the test body 1, and the first electrode 302p (see FIG. 13) and the second electrode 302n (see FIG. 14) in which grooves 361 (361a to 361d) are formed. See). As shown in FIG. 13, the positive electrode active material layer 36 p of the first electrode 302 p crosses the two groove portions 361 a extending along the short side of the current collector portion 351, and these groove portions 361 a, One groove portion 361b extending along the long side of the current collector portion 351 is formed. The grooves 361a and 361b are arranged at positions that do not intersect with the positive electrode side openings 262a and 262b of the separator 204. The widths of the groove portions 361a and 361b are 0.5 mm.

  As shown in FIG. 14, in the negative electrode active material layer 36n of the second electrode 302n, two groove portions 361c extending along the short side of the current collector portion 351, intersecting these groove portions 361c, One groove portion 361d extending along the long side of the current collector portion 351 is formed (see FIG. 14). The groove portions 361c and 361d are disposed at positions that do not intersect with the negative electrode side openings 264a and 264b of the separator 204. The widths of the groove portions 361c and 361d are 0.5 mm.

  Thus, the groove part 361 in the test body 2 does not communicate with the electrolyte flow path 26 of the separator 204. The test body 2 has the same configuration as the test body 1 except that the groove 361 is provided in the first electrode 302p and the second electrode 302n as described above.

<Test body 3>
The test body 3 is replaced with the first electrode 302p and the second electrode 302n of the test body 2, and the first electrode 303p (see FIG. 15) in which the groove portions 362 (362a to 362d) and the electrolyte channel 26 communicate with each other. And a second electrode 303n (see FIG. 16). As shown in FIG. 15, the positive electrode active material layer 36p of the first electrode 303p has two groove portions 362a extending in a direction parallel to the short side direction of the current collector portion 351, and these groove portions 362a. One groove portion 362b that intersects and extends along the long side of the current collector portion 351 is formed.

  The groove portion 362a is disposed at a position intersecting with two positive electrode side opening portions 262b extending from one short side 204c in the positive electrode side opening portion 262 of the separator 204. Further, the groove 362b is arranged at a position intersecting with three positive electrode side openings 262a extending from one long side 204a of the separator among the positive electrode side openings 262 of the separator 204. The width of these groove portions 362a and 362b is 0.5 mm.

  As shown in FIG. 16, the negative electrode active material layer 36n of the second electrode 303n includes two grooves 362c extending in a direction parallel to the short side direction of the current collector 351, and these grooves 362c. One groove portion 362d that intersects and extends along the long side of the current collector portion 351 is formed.

  The groove part 362c is arranged at a position intersecting two negative electrode side opening parts 264b extending from the other short side 204d in the negative electrode side opening part 264 of the separator 204. Further, the groove 362d is arranged at a position intersecting with the three negative electrode side openings 264a extending from the other long side 204b of the separator among the negative electrode side openings 264 of the separator 204. These grooves 362c and 362d have a width of 0.5 mm.

  As described above, the groove portion 362 in the test body 3 communicates with the electrolyte flow path 26 of the separator 204 through the positive electrode side opening 262 and the negative electrode side opening 264. The test body 3 has the same configuration as the test body 2 except that the arrangement of the groove portions 362 is changed as described above.

<Test body 4>
The test body 4 has the same configuration as the test body 1 except that the electrolyte channel 26 is not provided in the separator (not shown).

  Using these test bodies 1 to 4, internal resistance was measured by the following method. First, the test body was charged to 60% capacity in a fully charged state at a temperature of 0 ° C. From this state, the battery was discharged at a discharge rate of 1 C for 10 seconds, and a voltage drop due to discharge was measured. Then, the value of the resistance for 10 seconds was calculated by dividing the value of the voltage drop by the value of the discharge rate converted into a current value.

  Table 1 shows values obtained by normalizing the 10-second resistance values of the test specimens with the volume of the positive electrode active material layer. When this value is large, the internal resistance is high, and when the value is small, the internal resistance is small.

  As shown in Table 1, the test bodies 1 to 3 in which the electrolyte channel 26 was provided in the separator 204 exhibited a lower internal resistance than the test body 4 that did not have the electrolyte channel 26. From these results, it can be understood that by providing the electrolyte channel 26 in the separator 204, the electrolyte can be smoothly supplied to the positive electrode P, the negative electrode N, and the separator 204, and the internal resistance of the secondary battery can be reduced.

  Further, among the test bodies 1 to 3, the test body 3 in which the electrolyte flow path 26 of the separator 204 and the grooves 362 of the electrodes 303p and 303n communicate with each other is the test body 1 having no groove or the electrolyte flow The internal resistance was lower than that of the test body 2 in which the path 26 and the groove 361 were not in communication. In this way, not only the electrolyte channel 26 is provided in the separator 204 but also the electrodes 303p and 303n are provided with a groove 362, and the groove 362 and the electrolyte channel 26 are communicated with each other. It can be understood that the supply of the electrolytic solution to the separator 204 can be made smoother and the internal resistance of the secondary battery can be further reduced.

(Example 4)
This example is an example of the separator 205 in which the width of the electrolyte channel 27 becomes wider as it is closer to the outer peripheral edge. Although not shown in the drawing, the separator 205 of this example has a three-layer structure of the positive electrode side layer 22, the intermediate layer, and the negative electrode side layer, like the separator 203 of Example 3. The positive electrode side layer 22, the intermediate layer, and the negative electrode side layer are connected in the stacking order similarly to the separator of Example 3, and are folded at two folded portions.

  As shown in FIG. 17, the positive electrode side layer 22 is extended from three positive electrode side openings 272 a extending from one long side 205 c of the separator 205 and one short side 205 e of the separator 205. And two positive electrode side openings 272b. These positive electrode side openings 272a and 272b have an elongated slit shape, and the width becomes wider as the outer peripheral edge of the separator 205 is closer. Moreover, the positive electrode side opening parts 272a and 272b are also opened on the side peripheral surface of the separator 205, and also serve as the outer peripheral opening part 271.

  The negative electrode side layer has three negative electrode side openings 274a extending from the other long side 205d of the separator 205 in plan view, and two negative electrode side openings extending from the other short side 205f. 274b. These negative electrode side openings 274a and 274b are in the form of elongated slits, and the width becomes wider as the outer peripheral edge of the separator 205 is closer. Further, the negative electrode side openings 274 a and 274 b are also opened on the side peripheral surface of the separator 205, and also serve as the outer peripheral opening 271.

  The intermediate layer has a connection channel portion 263 that has an H shape in a plan view as viewed from the side where the positive electrode P is disposed. One vertical bar portion 263 a of the connection flow path portion 263 intersects with three positive electrode side opening portions 272 a extending from the long side 205 c of the separator 205 in the positive electrode side opening portion 272. In addition, the horizontal bar portion 263b of the connection flow path portion 263 includes two positive side opening portions 272b extending from the short side 205e of the separator 205 and two negative side portions extending from the short side 205f. It intersects with the opening 274b.

  The other vertical bar portion 263 c of the connection flow path portion 263 intersects three negative electrode side openings 274 a extending from the long side 205 d of the separator 205 in the negative electrode side opening 274. Others are the same as in the third embodiment.

  As in this example, the width of the electrolyte channel 27 is increased as the outer peripheral opening 271 is approached, so that the electrolyte solution outside the electrode assembly 11 is easily sucked into the electrolyte channel 27. In this case, the electrolyte solution or gas in the electrolyte channel 27 can be easily discharged to the outside of the electrode assembly 11. Therefore, according to the separator 205 of this example, the electrolyte solution is more smoothly supplied to the electrodes 31 and 32 during charging and discharging, and the release of gas from the inside of the electrode assembly 11 to the outside is further promoted. can do.

(Example 5)
This example is an example of the secondary battery 102 in which the outer peripheral opening 271 of the separator 205 is disposed at a position facing the liquid injection port 142 or the pressure release valve 143. As shown in FIG. 18, the secondary battery 102 of the present example has a substantially rectangular parallelepiped shape, and includes a case 14 having an open top surface and a bottom surface, and an electrode assembly 112 accommodated in the case 14. Yes. The metal foil 38 of the termination electrode 37 in the electrode assembly 112 is exposed on the top surface and the bottom surface of the case 14. Although not shown in the drawing, the metal foil 38 is in contact with a restraining member that restrains the electrode assembly 112 in the stacking direction.

  The side wall 141 of the case 14 is provided with a liquid injection port 142 for injecting an electrolyte into the case 14 and a pressure release valve 143 for releasing gas from the case 14 to the outside of the case 14. . As shown in FIG. 18, the liquid injection port 142 is closed by a plug 144 for preventing leakage of the electrolytic solution.

  As shown in FIG. 20, the electrode assembly 112 of this example includes a termination electrode 37, a bipolar electrode 32, and a separator 205. These electrodes 37 and 32 are stacked on each other via a separator 205. Further, the termination electrode 37 is disposed at the end of the electrode assembly 112 in the stacking direction. Note that the thickness of the metal foil 38 in the termination electrode 37 of this example is thicker than that of the metal foil 33 of the bipolar electrode 32.

  As shown in FIG. 20, the peripheral portion 331 of the metal foil 33 in the bipolar electrode 32 and the peripheral portion 381 of the metal foil 38 in the termination electrode 37 are covered with the sealing material 15. These sealing materials 15 are covered with a case 14. Further, the sealing materials 15 adjacent in the stacking direction of the electrode assemblies 112 are bonded to each other.

  As shown in FIGS. 19 to 21, a through hole 151 that penetrates the sealing material 15 is formed at a position facing the liquid injection port 142 in the sealing material 15. As shown in FIGS. 20 and 21, two negative electrode side openings 274 b extending from the short side 205 f of the separator 205 are disposed in front of the through hole 151.

  Further, as shown in FIG. 21, a through hole 152 that penetrates the sealing material 15 is also formed at a position facing the pressure release valve 143 in the sealing material 15. In the front surface of the through hole 152, a central negative electrode side opening 274a is arranged among the three negative electrode side openings 274a extending from the long side 205d of the separator 205. Others are the same as in the first embodiment.

  The secondary battery 102 of this example includes a case 14 that accommodates electrodes 37 and 32 as a positive electrode P and a negative electrode N, and a separator 205, and a liquid injection port that penetrates the case 14 and injects an electrolyte into the case 14 142. Further, the outer peripheral opening 271 in the separator 205 is disposed at a position facing the liquid injection port 142 as shown in FIG.

  Therefore, in the operation of impregnating the separator 205 with the electrolytic solution, the electrolytic solution injected from the liquid injection port 142 easily flows into the electrolytic solution flow path 27 of the separator 205. Then, by causing the electrolytic solution to flow into the electrolytic solution flow path 27, the separator 205 can be quickly impregnated with the electrolytic solution, and generation of a portion not impregnated with the electrolytic solution can be more effectively suppressed.

  Further, the secondary battery 102 is disposed on the case 14 for accommodating the electrodes 37 and 32 as the positive electrode P and the negative electrode N and the separator 205, and discharges gas from inside the case 14 to the outside of the case 14. Pressure release valve 143. And the outer periphery opening part 271 in the separator 205 is arrange | positioned in the position which faces the pressure release valve 143, as shown in FIG.

  As in this example, by arranging the outer peripheral opening 271 at a position facing the pressure release valve 143, the gas generated from the electrode during charge / discharge moves in the electrolyte flow path 27 and the front of the pressure release valve 143. Makes it easier to reach. Therefore, as the amount of gas increases, the electrolyte can be removed from the periphery of the pressure release valve 143. As a result, when the pressure in the case 14 becomes excessively high and the pressure release valve 143 is opened, the amount of the electrolyte discharged from the pressure release valve 143 can be further reduced. In addition, the secondary battery 102 of this example can achieve the same effects as those of the first and fourth embodiments.

  The aspects of the separator and the secondary battery according to the present invention are not limited to the aspects of the above-described examples and experimental examples, and the configuration can be changed as appropriate without departing from the spirit of the present invention. For example, although examples of separators having a multilayer structure are shown in the examples and experimental examples, an equivalent function can be realized as a separator having a single layer structure. As described above, the separator having a single layer structure can reduce the use area of the material as compared with the separator having a multilayer structure, and thus can reduce the material cost of the separator.

  In the examples and experimental examples, the positive electrode side openings 212, 252, and 262 and the negative electrode side openings 214, 254, and 264 are examples of separators that also serve as the outer peripheral openings 211, 251, and 261. An outer peripheral opening can be provided as an opening other than the positive electrode side opening and the negative electrode side opening. For example, the outer peripheral opening may be formed by extending a part of the connection flow path portion to the side peripheral surface of the separator and opening the separator on the side peripheral surface.

  Further, in the fifth embodiment, the example of the secondary battery 102 in which the liquid injection port 142 and the pressure release valve 143 are separately provided is shown, but after the electrolyte is injected from the liquid injection port 142, the liquid injection port A pressure relief valve 143 may be attached to 142. The number of the outer peripheral openings 271 disposed so as to face the liquid injection port 142 may be one, or may be two or more as in the fifth embodiment. Further, the number of the outer peripheral openings 271 disposed so as to face the pressure release valve 143 may be one as in the fifth embodiment, or may be two or more.

1, 102 Secondary battery 2, 202, 203, 204, 205 Separator 21, 25, 26, 27 Electrolyte flow path 211, 251, 261, 271 Peripheral opening 212, 252, 262, 272 Positive electrode side opening 213, 253, 263 Connection flow path 214, 254, 264, 274 Negative electrode side opening P Positive electrode N Negative electrode C Single cell

Claims (10)

A separator interposed between a positive electrode and a negative electrode in a secondary battery,
An outer peripheral opening that opens on the side peripheral surface, a positive electrode opening that opens on the positive electrode surface, a negative electrode opening that opens on the negative electrode surface, and a connection channel that connects the openings to each other An electrolyte flow path with a portion,
The positive electrode side opening, the negative electrode side opening, and the connection channel portion are arranged so that a through hole penetrating the separator is not formed in a plan view as viewed from the side where the positive electrode is arranged. Separator.   In a plan view as viewed from the side where the positive electrode is disposed, the positive electrode side opening is disposed at a position different from the negative electrode side opening of the electrolyte flow path provided with the positive electrode side opening. The separator according to claim 1.   The separator includes a positive electrode side layer provided with the positive electrode side opening, a negative electrode side layer provided with the negative electrode side opening, and the connection flow path portion, and is provided between the positive electrode side layer and the negative electrode side layer. 3. A multilayer structure including one or more intermediate layers interposed in the multilayer structure, and at least one of the layers constituting the multilayer structure has the outer peripheral opening. Separator.   The separator according to claim 3, wherein each layer constituting the multilayer structure in the separator is continuous. A secondary battery comprising the separator according to any one of claims 1 to 4,
A positive electrode;
The separator laminated on the positive electrode;
A negative electrode laminated on the separator;
A secondary battery having one or more single cells provided with an electrolytic solution interposed between the positive electrode and the negative electrode.   6. The secondary battery according to claim 5, wherein at least one of the positive electrode and the negative electrode has a groove portion opened on a side peripheral surface of the electrode.   The secondary battery according to claim 6, wherein the groove portion communicates with the electrolyte flow path of the separator.   The secondary battery according to any one of claims 5 to 7, which is a nickel metal hydride storage battery.   The secondary battery includes a case that houses the positive electrode, the separator, and the negative electrode, and a liquid injection port that penetrates the case and injects an electrolyte into the case. The secondary battery according to claim 5, wherein the outer peripheral opening is disposed at a position facing the liquid injection port.   The secondary battery includes a case that houses the positive electrode, the separator, and the negative electrode, and a pressure release valve that is disposed on the case and discharges gas from inside the case to the outside of the case. The secondary battery according to claim 5, wherein the outer peripheral opening in the separator is disposed at a position facing the pressure release valve.

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