JP4785360B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery, and particularly relates to a safety measure when overcharge occurs.

  In recent years, development of mobile devices such as notebook computers and mobile phones has been rapidly advanced. A secondary battery such as a lithium ion battery is often used as a power source for these mobile devices. The secondary battery is required to have characteristics such as light weight, small size, and large capacity in order to improve the driving time and portability of the device.

  A lithium ion battery, which is a secondary battery, has a laminated element sealed inside an exterior material. The multilayer element includes a plurality of positive electrode sheets and negative electrode sheets that are alternately stacked, and a separator and an electrolyte are interposed between each positive electrode sheet and each negative electrode sheet. The separator and the electrolyte include a solid or gel electrolyte that has both functions as one, and a separator that is impregnated with a liquid electrolyte.

The positive electrode sheet is coated with a positive electrode active material such as LiCoO ₂ , and the negative electrode sheet is coated with a negative electrode active material such as graphite (C). Thus, in the laminated element, charging or discharging is performed by moving lithium ions (Li ⁺ ) between the positive electrode sheet and the negative electrode sheet.

  In addition, it is known that an exterior film such as an aluminum laminate or a metal can is applied to the exterior material. In particular, the exterior film is light in weight, easy to be thinned, and free in shape. It is advantageous in that the degree is high.

  By the way, when the lithium ion battery is erroneously excessively charged, a large current flows between the positive electrode sheet and the negative electrode sheet, whereby the electrolyte is decomposed or vaporized to generate gas. As a result, there arises a problem that the exterior film expands and bursts or ignites.

  On the other hand, for the purpose of preventing ignition, it is known to fill a flame retardant gel in the exterior film. However, although the flame-retardant gel can suppress ignition during overcharge, it does not suppress the generation of gas in the exterior film, and thus cannot prevent the exterior film from bursting.

  Therefore, conventionally, it has been known that a safety valve (rupture) is formed on the exterior film, and when the gas pressure increases inside the exterior film, the safety valve is activated to release the gas in the exterior film to the outside. (For example, see Patent Documents 1 and 2).

  Patent Document 1 describes that a low temperature fusion part functioning as a safety valve is provided in at least one place of a sealing part by heat fusion of a film exterior material. Further, in Patent Document 2, the width of the heat-sealed sealing portion where the current collecting lead is attached to the secondary battery sealed with the bag-shaped outer film is set as the heat welding where the current collecting lead is not attached. It is disclosed to make it larger than the width of the sealing part (used as a safety valve).

  However, in these safety valves, the safety valve does not operate unless the internal pressure of the exterior film is considerably increased, and the electrolyte may leak and ignite, so that the safety is not sufficient. In addition, since the charging current continues to flow, the generation of gas cannot be stopped.

  On the other hand, it is known to provide a shut-off mechanism that shuts off energization by expansion of the exterior film (see, for example, Patent Document 3).

  That is, as shown in FIG. 10 which is a cross-sectional view in a cut-off state, the laminated element 101 is sealed inside the exterior film 121, and the negative electrode sheet 102 and the positive electrode sheet 103 are alternately laminated with the separator 104 interposed therebetween. Has been.

  A negative electrode terminal 112 is connected to the conductive member 125 provided on the outermost surface of the multilayer element 101 via an adhesive tape 114. A connection portion 111 fixed to the inner surface of the exterior film 121 is formed at one end of the negative electrode terminal 112. On the other hand, the other end of the negative electrode terminal 112 extends to the outside of the exterior film 121.

When the exterior film 121 is not expanded, the connection portion 111 is pressed by the exterior film 121 to contact the conductive member 125 and is energized. On the other hand, when gas is generated due to overcharging, the connecting film 111 is separated from the conductive member 125 due to expansion of the exterior film by the gas. As a result, the energization state to the multilayer element 101 is interrupted, and the generation of gas can be stopped.
JP 2000-1000039 A JP 2000-277065 A JP 2003-208885 A

  However, although the secondary battery of Patent Document 3 can shut off the energized state at a stage where the gas pressure in the exterior film is relatively low compared to those of Patent Documents 1 and 2 using a safety valve, The occurrence itself cannot be prevented. In other words, there is a problem that the energized state cannot be interrupted before the gas is generated.

  Further, when the temperature in the exterior film 121 is lowered, the electrolyte gas is liquefied and the exterior film 121 contracts, so that the connecting portion 111 of the negative electrode terminal 112 comes into contact with the conductive member 125 again. As a result, there is a possibility that gas is regenerated due to the over-charging being performed again when the power is turned on.

  The present invention has been made in view of such various points, and an object of the present invention is to cut off the energized state of the laminated element before gas is generated inside the exterior film.

  In order to achieve the above object, the present invention is provided with a shut-off mechanism that shuts off the energized state when the thickness in the stacking direction of the stacking elements becomes larger than a predetermined thickness.

  Specifically, the secondary battery according to the present invention includes a laminated element in which a negative electrode sheet and a positive electrode sheet are alternately laminated with a separator interposed therebetween, an exterior film that seals the laminated element, and a negative electrode of the laminated element A secondary battery including a pair of electrode terminals that are electrically connected to a sheet or a positive electrode sheet and extended to the outside of the exterior film, and the thickness in the stacking direction of the stacked element is charged to the maximum capacity When the thickness is larger than the thickness, a shut-off mechanism for shutting off the energized state between at least one of the pair of electrode terminals and the laminated element is provided.

Further, the multilayer element is formed with a through hole extending in the lamination direction, and the blocking mechanism is fixed to the conductive pin disposed inside the through hole and one of the multilayer outermost surfaces of the multilayer element. A first conductive member that is in contact with one end of the pin, and a second conductive member that is fixed to the other outermost surface of the multilayer element and is in contact with the other end of the pin; The first conductive member is connected to the negative electrode sheet or a collector electrode that is conducted to the positive electrode sheet, and the second conductive member is the collector electrode to which the first conductive member is connected that is connected to the electrode terminals of the same polarity as.

On the other hand , a through hole extending in the stacking direction is formed in the stacked element, and the blocking mechanism is fixed to the conductive pin disposed inside the through hole and one stacked outermost surface of the stacked element. A first conductive member that is welded to one end of the pin, and a second conductive member that is fixedly attached to the other laminated outermost surface of the laminated element and is welded to the other end of the pin; The first conductive member is connected to the negative electrode sheet or a collector electrode that is conducted to the positive electrode sheet, and the second conductive member is the collector electrode to which the first conductive member is connected And may be connected to the electrode terminal having the same polarity.

-Action-
Next, the operation of the present invention will be described.

  At the normal time when no overcharge occurs, the shut-off mechanism does not operate, and the energized state between the pair of electrode terminals and the laminated element is maintained. As a result, charge is supplied from the external power source to the negative electrode sheet of the multilayer element via the electrode terminal, so that the secondary battery is normally charged.

  By the way, at the time of charge, positive ions are released from the positive electrode sheet. As a result, since the crystal lattice of the positive electrode sheet is elongated, the positive electrode sheet expands. In addition, since the positive ions released from the positive electrode sheet are taken into the negative electrode sheet, the negative electrode sheet also expands. In other words, the laminated element expands with charging.

  When an overcharge occurs, the thickness of the stacked elements in the stacking direction becomes larger than the thickness when the secondary battery is charged to the maximum capacity (for example, a voltage of 4.25 V). At this time, the shut-off mechanism operates to shut off the energization state between at least one of the pair of electrode terminals and the laminated element. As a result, supply of electric charges to the negative electrode sheet of the laminated element is blocked, and gas generation in the exterior film is prevented beforehand.

That is , the blocking mechanism includes a pin provided in a through hole formed in the laminated element, and a first conductive member and a second conductive member that are in contact with or welded to both ends of the pin. For example, a current collecting electrode is electrically connected to each negative electrode sheet, and the current collecting electrode is connected to a first conductive member fixed to one outermost surface of the laminated element. The second conductive member is electrically connected to the first conductive member via a pin, and a negative electrode terminal is connected thereto. That is, during normal operation, the charge supplied from the electrode terminal of the negative electrode is supplied to each negative electrode sheet of the laminated element through the second conductive member, the pin, the first conductive member, and the current collecting electrode, and thus charged. Is done.

  On the other hand, at the time of abnormality, the thickness of the stacked elements increases in the stacking direction, and at least one of the first conductive member and the second conductive member is detached from the end portion of the pin. As a result, since the path of the charge charged between at least one of the first conductive member and the second conductive member and the end of the pin is interrupted, the supply of charge from the electrode terminal to the negative electrode sheet is prevented, Generation of gas is prevented in advance.

According to the present invention, in an abnormal state in which the thickness in the stacking direction of the multilayer element is larger than the thickness when charged to the maximum capacity due to overcharging, the energization state between at least one of the pair of electrode terminals and the multilayer element is changed. comprising a blocking mechanism for blocking the pin provided in the through hole of the product layer element, by constituting a blocking mechanism by the first and second conductive members that are in contact or welded to both ends of the pin, at the abnormal time, At least one of the first conductive member and the second conductive member can be detached from the end of the pin. As a result, since the charging path can be divided, the generation of gas can be prevented in advance.

  In addition, since no gas is generated, there is no problem of re-contacting the current-canceling part due to liquefaction of the gas due to the temperature drop, unlike a secondary battery using a conventional safety valve. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

Embodiment 1 of the Invention
1 to 7 show Embodiment 1 of a secondary battery according to the present invention. The secondary battery of the present embodiment is a so-called sheet battery, for example, a lithium ion battery that performs charging and discharging by moving lithium ions (Li ⁺ ) between electrodes.

  As shown in FIG. 1, which is a cross-sectional view, the secondary battery 1 includes a laminated element 10, an exterior film 30 that seals the laminated element 10 therein, and a pair of electrode terminals 15 that are electrically connected to the laminated element 10. 16.

  As shown in FIG. 1 and FIG. 3 which is a perspective view, the laminated element 10 has a structure in which a plurality of negative electrode sheets 11 and a plurality of positive electrode sheets 12 are alternately laminated with separators 13 interposed therebetween.

  As shown in FIG. 4, the negative electrode sheet 11 and the positive electrode sheet 12 are composed of sheet-like electrode bodies 11a and 12a and electrode tabs 11b and 12b.

  A circular first opening 31 is formed in the approximate center of the electrode body 11 a of the negative electrode sheet 11. On the other hand, a circular second opening 32 is formed in the approximate center of the electrode body 12 a of the positive electrode sheet 12. The center of the first opening 31 coincides with the center of the second opening 32 in a state where the negative electrode sheet 11 and the positive electrode sheet 12 are laminated. Further, the separator 13 is also formed with a circular third opening 33. The center of the third opening 33 coincides with the centers of the first opening 31 and the second opening 32.

  As shown in FIG. 1, the inner diameter of the third opening 33 of the separator 13 is the smallest among the openings 31, 32, 33. The inner diameter of the first opening 31 of the negative electrode sheet 11 is larger than that of the third opening 33. And the internal diameter of the 2nd opening part 32 of the positive electrode sheet 12 is larger than the said 1st opening part 31, and is the largest. Through the first to third openings 31, 32 and 33, a through hole 19 extending in the stacking direction of the stacked element 10 is formed.

  The negative electrode sheet 11 is formed of a foil of a conductor such as copper, nickel, silver, and SUS having a thickness of 5 to 100 μm, particularly 8 to 50 μm. The electrode body 11a of the negative electrode sheet 11 is coated with a negative electrode active material on the surface, while the electrode tab 11b is exposed without being coated with the negative electrode active material.

The negative electrode active material is a carbonaceous material, and various natural graphites and artificial graphites such as graphite, for example, graphites such as fibrous graphite, scaly graphite, and spherical graphite are preferable. Such graphite is mixed with a binder such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, ethylene-propylene-diene polymer, and coated on both surfaces of the conductor foil. The thickness of the negative electrode active material is preferably 20 to 500 μm, and more preferably 50 to 250 μm. Moreover, when the density of the negative electrode active material layer when it becomes a product battery is set to a high density of about 1.2 to 1.8 g / cm ³ , battery characteristics are excellent, which is preferable.

  The positive electrode sheet 12 is made of a conductive foil such as aluminum, aluminum alloy, and titanium having a thickness of 10 to 100 μm, particularly 15 to 50 μm, and an expanded metal or mesh having a thickness of 25 to 300 μm, particularly 30 to 150 μm. It is made of metal or the like. Similar to the negative electrode sheet 11, the electrode body 12a of the positive electrode sheet 12 is coated with a positive electrode active material on the surface, while the electrode tab 12b is exposed without being coated with the positive electrode active material.

LiCoO ₂ is applied to the positive electrode active material. In addition, the positive electrode active material has a potential difference of at least 1 V with respect to the negative electrode, for example, V ₂ O ₅ , MnO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Co _0.5 O ₂ , LiNiO ₂ , Li -Co-P-based composite oxides (LiCo _0.5 P _0.5 O ₂ , LiCo _0.4 P _0.6 O ₂ , LiCo _0.6 P _0.4 O ₂ , LiCo _0.3 Ni _0.3 P _0.4 O ₂ , LiCo _0.2 Ni _0.2 P _0.6 O _2, etc.), TiS ₂ , MoS ₂ , MoO _3, etc. can also be applied.

In particular, a Li—Co-based composite oxide is preferable because the electromotive force and charge / discharge voltage of the battery can be increased. The positive electrode active material preferably has a particle size of 1 to 50 μm because battery characteristics are improved. Such a positive electrode active material is coated by mixing a binder such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or ethylene-propylene-diene polymer. The thickness of the positive electrode active material is preferably 20 to 500 μm, and more preferably 50 to 250 μm. Further, when the density of the positive electrode active material layer when it is a product battery is set to a high density of about 2.5 to 3.5 g / cm ³ , the battery characteristics are excellent, which is preferable.

  Although the coating method of a negative electrode active material and a positive electrode active material is not specifically limited, A roll coating method, a die coating method, etc. are preferable.

  Each of the electrode tabs 11b and 12b protrudes from one side surface of the multilayer element 10 as shown in FIGS. The negative electrode tabs 11b are arranged vertically and connected to the negative collector electrode 21 together. The positive electrode tabs 12b are also arranged vertically and connected together to the positive collector electrode 22. That is, each negative electrode sheet 11 is electrically connected to the negative current collecting electrode 21, while each positive electrode sheet 12 is electrically connected to the positive current collecting electrode 22.

  The separator 13 may be a plurality of sheet-shaped members individually interposed between the negative electrode sheet 11 and the positive electrode sheet 12, and in addition, as shown in FIG. And may be interposed between the negative electrode sheet 11 and the positive electrode sheet 12.

  In addition, the separator 13 may be any material as long as it has ionic conductivity while preventing a short circuit between the positive electrode and the negative electrode. However, the ease of handling, electrical characteristics, stability to the electrolyte, etc. From the viewpoint, a polymer film having porosity is preferable. Examples of the polymer constituting the polymer film include polystyrene, polybutadiene and copolymers thereof, polyethylene oxide derivatives, polypropylene oxide derivatives, polymers containing the above derivatives, polyacrylonitrile, polyvinyl pyrrolidone, polyvinylidene carbonate, polyvinylidene fluoride, A copolymer of vinylidene fluoride and hexafluoropropylene or the like can be used. Such a polymer is dissolved in an appropriate solvent, and the film is formed and dried to form a film. An additive such as a plasticizer may be added to the film-forming solution. In this way, the separator 13 having porosity is produced. The thickness of the separator 13 is preferably 5 to 100 [mu] m, and more preferably 20 to 60 [mu] m, since the battery characteristics are good.

When the battery is completed, the separator 13 is impregnated with a non-aqueous electrolyte. As the electrolytic solution, an electrolytic solution in which salts are dissolved in an organic solvent can be applied. Examples of the salts include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiAlCl ₄ , Li (CF ₃ SO ₂ ) ₂ N, and the like, and one or a mixture of two or more thereof can be applied. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, dimethyl sulfoxide, sulfolane, γ-butyrolactone, 1,2-dimethoxymethane, N, N-dimethylformamide, tetrahydrofuran, 1,3-dioxolane, 2-methyltetrahydrofuran, Examples include diethyl ether, and one or a mixture of two or more of these can be applied.

  Further, as the separator 13, a known solid electrolyte layer that substantially separates the negative electrode sheet 11 and the positive electrode sheet 12 may be used.

  The exterior film 30 is formed in a blister packaging container as shown in FIG. 2 which is a plan view. Although not shown, the exterior film 30 is made of an aluminum foil layer having a thickness of 30 to 50 μm, an external protective layer made of a resin laminated on one surface of the aluminum foil layer, and a resin laminated on the other surface of the aluminum foil. And an adhesive layer made of a thermoplastic resin laminated on the electrolyte solution layer, and has a four-layer structure. Examples of the resin for the external protective layer include a nylon resin and a polyester resin, and examples of the resin for the adhesive layer include a resin that can be sealed by heat fusion such as a modified polyolefin resin.

  The thickness of the exterior film 30 is preferably 80 to 200 μm as a whole. The exterior film 30 has a rectangular blister (dent) slightly larger than the outer shape of the laminated element 10 formed on a rectangular film. Then, in a state where the laminated element 10 is accommodated in the blister and the electrolytic solution is introduced, the exterior film 30 is folded in two and bonded by heat fusion or the like, and the laminated element 10 is sealed.

  As shown in FIG. 3, one end of the pair of electrode terminals 15 and 16 is electrically connected to the positive electrode sheet 12 or the negative electrode sheet 11, and extends to the outside of the exterior film 30 as shown in FIGS. 1 and 2. Yes.

  That is, the electrode terminals 15 and 16 are constituted by the negative electrode terminal 15 and the positive electrode terminal 16. As shown in FIG. 3, one end of the negative electrode terminal 15 is electrically connected to a second conductive member 25 described later. On the other hand, one end of the positive electrode terminal 16 is connected to the positive collector electrode 22.

  As a feature of the present invention, the secondary battery 1 has the pair of electrode terminals 15 and 16 when the thickness in the stacking direction of the stacking element 10 becomes larger than the thickness when charged to the maximum capacity. The interruption | blocking mechanism 40 which interrupts | blocks the electricity supply state of at least one and the laminated element 10 is provided.

  The blocking mechanism 40 has a pin 41, a first conductive member 24, and a second conductive member 25.

  The pin 41 is disposed inside the through hole 19 of the multilayer element 10 and is made of a conductive material such as copper. The pin 41 has such a rigidity that it is not deformed by the expansion force of the laminated element 10. In the present embodiment, the pin 41 has the same length as the thickness of the stacked element 10 in the stacking direction. Further, the outer diameter of the pin 41 is slightly smaller than the inner diameter of the third opening 33 of the separator 13.

  As shown in FIG. 1, the first conductive member 24 is fixedly provided on the lower surface which is one outermost surface of the multilayer element 10 and is in contact with the lower end which is one end of the pin 41. On the other hand, the second conductive member 25 is fixedly provided on the upper surface which is the other outermost surface of the multilayer element 10 and is in contact with the upper end which is the other end of the pin 41. That is, the first conductive member 24 and the second conductive member 25 are electrically connected via the pin 41.

  The first conductive member 24 and the second conductive member 25 are each made of, for example, copper foil. As shown in FIG. 1, similarly to the negative electrode sheet 11, an electrode tab 26 is formed on the first conductive member 24, and an electrode tab 27 is formed on the second conductive member 25. The electrode tabs 26 and 27 are arranged so as to overlap the negative current collecting electrode 21 in the vertical direction.

  The electrode tab 26 of the first conductive member 24 is connected to the negative collector electrode 21. On the other hand, the electrode tab 27 of the second conductive member 25 is connected to the negative electrode terminal 15, which is an electrode terminal having the same polarity as the negative current collecting electrode 21.

-Reaction during charging-
Next, the reaction between the positive electrode and the negative electrode during charging of the secondary battery 1 in which LiCoO ₂ is applied as the positive electrode active material will be described.

  At the time of charging, the chemical reaction of the following formula (1) is performed at the positive electrode.

LiCoO ₂ → Li _1-x CoO ₂ + xLi ⁺ + xe ⁻ (1)
In the negative electrode, the chemical reaction of the following formula (2) is performed.

_{^{C y + xLi + + xe -}} → C y Li x ··· (2)
As a result, the chemical reaction of the following formula (3) is performed as the whole of the negative electrode sheet 11 and the positive electrode sheet 12.

LiCoO ₂ + C _y → Li _1-x CoO ₂ + C _y Li _x (3)
Charging is performed by the above reaction. At this time, the internal voltage of the multilayer element 10 when charged to the maximum capacity by the CCCV charging method is, for example, 4.25V.

At the time of charging, since lithium ions (Li ⁺ ) are released from the positive electrode active material, elongation occurs in the crystal lattice of the positive electrode active material, and the positive electrode sheet 12 expands. In addition, since the negative electrode active material takes in lithium ions (Li ⁺ ) released from the positive electrode active material, the negative electrode sheet 11 also expands. That is, the stacked element 10 expands in the stacking direction with charging.

-Operation of shut-off mechanism in case of abnormality
Next, the operation of the shut-off mechanism 40 at the time of abnormality in which overcharging has occurred will be described.

  The thickness of the laminated element 10 increases with excessive charging even in an abnormal state. On the other hand, since the pin 41 is defined to have the same length as the thickness of the multilayer element 10 when charged to the maximum capacity, when the amount of charge exceeds the maximum capacity, the thickness of the multilayer element 10 is Greater than the length of As a result, the pin 41 that has been in contact with each other until then is separated from at least one of the first conductive member 24 and the second conductive member 25. 6 shows a state in which the pin 41 is detached from only the second conductive member 25, and FIG. 7 shows a state in which the pin 41 is detached from both the first conductive member 24 and the second conductive member 25.

  As a result, the charging path from the external power source to the multilayer element 10 is cut off, so that the energized state is cut off and charging is stopped.

-Effect of Embodiment 1-
Therefore, according to the first embodiment, since the shut-off mechanism 40 is provided, the shut-off mechanism is provided at the time of abnormality in which the thickness in the stacking direction of the multilayer element 10 becomes larger than the thickness when charged to the maximum capacity due to overcharging. Forty pins 41 can be detached from at least one of the first conductive member 24 and the second conductive member 25, and the energized state between the negative electrode terminal 15 and the laminated element 10 can be cut off.

  As a result, since the energized state can be interrupted before the electrolyte is gasified, the generation of gas in the exterior film 30 can be prevented in advance, and the safety during overcharging can be dramatically improved.

  In addition, since no gas is generated, there is no problem of re-contacting the current-canceling part due to liquefaction of the gas due to the temperature drop, unlike a secondary battery using a conventional safety valve. Can do.

<< Embodiment 2 >>
FIG. 8 shows a second embodiment of the secondary battery according to the present invention. In addition, the same code | symbol is attached | subjected about the same part as FIGS.

  The blocking mechanism 40 of this embodiment includes a pin 41 and a third conductive member 46 instead of the pin 41 in the first embodiment. For example, the third conductive member 46 is formed in a cylindrical shape having substantially the same diameter as the pin 41. The sum of the lengths of the third conductive member 46 and the pin 41 is the same as the length of the pin 41 in the first embodiment, and the thickness of the multilayer element 10 when the secondary battery 1 is charged to the maximum capacity. It is prescribed to the same length.

  The third conductive member 46 is in contact with both the lower surface of the second conductive member 25 and the upper surface of the pin 41 in a normal state. And, at the time of an abnormality in which overcharge occurs, the thickness of the laminated element 10 becomes larger than the thickness when charged to the maximum capacity, so that between the third conductive member 46 and the second conductive member 25 or the pin 41, Alternatively, a gap is generated between the pin 41 and the first conductive member 24. As a result, the charging path from the external power source to the laminated element 10 is cut off, and the energized state is cut off.

  Therefore, according to the second embodiment, similarly to the first embodiment, generation of gas in the exterior film 30 can be prevented in advance.

  The third conductive member 46 may be fixedly provided on the lower surface of the second conductive member 25, for example. This makes it possible to interrupt the energized state by causing the lower surface of the third conductive member 46 to be detached from the upper surface of the pin 41 in the event of an abnormality in which overcharging has occurred.

<< Embodiment 3 >>
FIG. 9 shows Embodiment 3 of the secondary battery according to the present invention. In this embodiment, the third conductive member 46 is provided on the upper end side of the pin 41 and the fourth conductive member 47 is provided on the lower end side of the pin 41 as in the second embodiment.

  That is, the fourth conductive member 47 is formed in a columnar shape having substantially the same diameter as the pin 41, for example, similarly to the third conductive member 46. The sum of the lengths of the fourth conductive member 47, the third conductive member 46, and the pin 41 is the same as the length of the pin 41 in the first embodiment, and the secondary battery 1 is charged to the maximum capacity. The same length as the thickness of the laminated element 10 is defined.

  The third conductive member 46 is in contact with both the lower surface of the second conductive member 25 and the upper surface of the pin 41 in a normal state. On the other hand, the fourth conductive member 47 is in contact with both the lower surface of the pin 41 and the upper surface of the first conductive member 24 in a normal state.

  And, at the time of an abnormality in which overcharge occurs, the thickness of the laminated element 10 becomes larger than the thickness when charged to the maximum capacity, so that between the third conductive member 46 and the second conductive member 25 or the pin 41, Alternatively, a gap is generated between the fourth conductive member 47 and the pin 41 or the first conductive member 24. As a result, the charging path from the external power source to the laminated element 10 is cut off, and the energized state is cut off. Therefore, also in this third embodiment, the generation of gas in the exterior film 30 can be prevented in advance, as in the above embodiments.

  For example, the fourth conductive member 47 may be fixedly provided on the upper surface of the first conductive member 24. As a result, when an overcharge occurs, the upper surface of the fourth conductive member 47 can be separated from the lower surface of the pin 41 to interrupt the energized state.

<< Other Embodiments >>
In each of the above embodiments, the pin 41 is sandwiched and fixed between the first conductive member 24 and the second conductive member 25 in a normal state. However, the present invention is not limited to this, and for example, spot welding. It may be fixed by, for example.

  That is, in the first embodiment, the upper end of the pin 41 and the lower surface of the second conductive member 25 are welded, and the lower end of the pin 41 and the upper surface of the first conductive member 24 are welded to fix the pin 41. Is possible. In the second embodiment, the upper end of the pin 41 and the lower surface of the third conductive member 46 may be welded. Further, in the third embodiment, the upper end of the pin 41 and the lower surface of the third conductive member 46 may be welded, and the lower end of the pin 41 and the upper surface of the fourth conductive member 47 may be welded and fixed.

  When welding and fixing in this way, the length of the pin 41 can be made slightly shorter than the thickness of the multilayer element 10 when charged to the maximum capacity. This makes it possible to adjust the ease of detachment between the pin 41 and each conductive member at the time of abnormality.

  As described above, the present invention is useful for a secondary battery having a laminated element sealed in an exterior film, and in particular, before the gas is generated inside the exterior film, the energization state of the laminated element is in advance. This is suitable for blocking.

1 is a cross-sectional view schematically showing a secondary battery of Embodiment 1. FIG. It is a top view which shows the external appearance of a secondary battery. 1 is a perspective view showing a multilayer element according to Embodiment 1. FIG. It is a perspective view which shows the external appearance of a negative electrode sheet (positive electrode sheet). It is a perspective view which shows the state which provided the separator in folding shape. It is sectional drawing which shows the interruption | blocking state of the interruption | blocking mechanism from which the pin detach | leaved from the 2nd electrically-conductive member. It is sectional drawing which shows the interruption | blocking state of the interruption | blocking mechanism which the pin removed from the 1st and 2nd electrically-conductive member. 6 is a cross-sectional view showing a main part of a secondary battery according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view showing a main part of a secondary battery according to Embodiment 3. It is sectional drawing which shows the conventional secondary battery.

1 Secondary battery 10 Multilayer element
11 Negative electrode sheet
12 Positive electrode sheet
13 Separator 15 Negative terminal (electrode terminal)
16 Positive terminal (electrode terminal)
19 through-hole 21 current collecting electrode 22 current collecting electrode 24 first conductive member 25 second conductive member 30 exterior film 40 blocking mechanism 41 pin

Claims (2)

A laminated element in which a negative electrode sheet and a positive electrode sheet are alternately laminated with a separator interposed therebetween;
An exterior film sealing the laminated element;
A secondary battery comprising a pair of electrode terminals that are electrically connected to the negative electrode sheet or the positive electrode sheet of the laminated element and extended to the outside of the exterior film,
Provided with a shut-off mechanism that shuts off the energization state between at least one of the pair of electrode terminals and the laminated element when the thickness in the laminating direction of the laminated element is larger than the thickness when charged to the maximum capacity. ,
In the laminated element, a through hole extending in the laminating direction is formed,
The blocking mechanism includes a conductive pin disposed inside the through hole, a first conductive member that is fixed to one outermost surface of the multilayer element and is in contact with one end of the pin; A second conductive member that is fixedly attached to the other outermost surface of the laminated element and is in contact with the other end of the pin,
The first conductive member is connected to a current collecting electrode that is electrically connected to the negative electrode sheet or the positive electrode sheet,
The secondary battery, wherein the second conductive member is connected to the electrode terminal having the same polarity as the current collecting electrode to which the first conductive member is connected. A laminated element in which a negative electrode sheet and a positive electrode sheet are alternately laminated with a separator interposed therebetween;
An exterior film sealing the laminated element;
A secondary battery comprising a pair of electrode terminals that are electrically connected to the negative electrode sheet or the positive electrode sheet of the laminated element and extended to the outside of the exterior film,
Provided with a shut-off mechanism that shuts off the energization state between at least one of the pair of electrode terminals and the laminated element when the thickness in the laminating direction of the laminated element is larger than the thickness when charged to the maximum capacity. ,
In the laminated element, a through hole extending in the laminating direction is formed,
The blocking mechanism includes a conductive pin disposed inside the through-hole, a first conductive member fixedly provided on one outermost surface of the stacked element, and welded to one end of the pin; A second conductive member fixed to the other outermost surface of the laminated element and welded to the other end of the pin;
The first conductive member is connected to a current collecting electrode that is electrically connected to the negative electrode sheet or the positive electrode sheet,
The secondary battery, wherein the second conductive member is connected to the electrode terminal having the same polarity as the current collecting electrode to which the first conductive member is connected.

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