JP2014056716A - Sealed secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed secondary battery provided with a high heat resistant current cut-off mechanism to prevent a collector plate from being fused by Joule heat when charged at high rate.SOLUTION: A current cut-off mechanism 80 of a sealed secondary battery is constructed so that when the internal pressure of a case rises exceeding a prescribed level, a reversal plate 30 is deformed so as to be separated from a collector plate 72 formed in shape of a rectangular plate by the internal pressure and the collector plate is thereby broken at a portion of an annular groove 79 of a center thin wall section 74 of the collector plate, and that a groove 90 is formed at least on the surface facing a wound electrode body 50 of the surfaces of a thick wall section 78 of the collector plate 72, the groove 90 being depressed from the surface of the thick wall section 78.

Description

  The present invention relates to a sealed secondary battery (typically a sealed secondary battery whose overall shape is a square (cuboid shape)). Specifically, the present invention relates to a sealed secondary battery provided with a current interrupting mechanism that operates by increasing internal pressure.

  In recent years, secondary batteries such as lithium secondary batteries and nickel metal hydride batteries are preferably used as so-called portable power sources such as personal computers and portable terminals, and vehicle drive power sources. In particular, a lithium secondary battery that is lightweight and has a high energy density is expected to be preferably used as a high-output power source for driving vehicles such as electric vehicles and hybrid vehicles.

  As a typical structure of such a secondary battery, a battery having a sealed structure (sealed battery) in which an electrode body including a positive electrode and a negative electrode is sealed in a battery case together with an electrolyte (for example, a non-aqueous electrolyte). Is mentioned. When charging this type of battery, if there is a malfunction due to the presence of a defective battery or a failure of the charging device, it is assumed that a current exceeding the normal level is supplied to the battery, resulting in an overcharged state. During such overcharge, the battery reaction proceeds rapidly, gas is generated inside the sealed battery case, the internal pressure of the battery case rises, and the abnormal internal pressure (gas pressure) deforms the case. Etc. may occur. In order to cope with such abnormalities, as a conventional technology, current interruption is performed by deforming parts using the pressure (gas pressure) inside the case that accompanies abnormalities in the battery and physically breaking the energized part. A battery structure with a mechanism has been proposed.

  For example, Patent Document 1 is given as a conventional example related to a secondary battery having a current interruption mechanism having such a configuration. The current interrupting mechanism described in this document includes a rectangular plate-shaped current collecting plate, and a reversing plate (current interrupting valve) welded to a part of the current collecting plate so as to allow energization. The rectangular plate-shaped current collector is connected to an electrode body housed inside the case of the square-shaped sealed secondary battery. When the case internal pressure (gas pressure) rises, the current interruption mechanism reverses and deforms the reversing plate away from the electrode body and the current collector plate by the gas pressure, and the welded part is deformed along with the deformation. A part of the current collector is included so as to be broken. In this way, the reversal plate is reversed and deformed and detached from the current collector body, thereby realizing current interruption.

JP 2010-212034 A

  In the current interruption mechanism configured as described in Patent Document 1 above, in order to realize that the current is correctly interrupted when reaching a preset case internal pressure (that is, a predetermined gas pressure), the case internal pressure In order for the current collector plate including the welded portion to be quickly broken along with the reversal / deformation of the reversal plate (current cutoff valve) when the current reaches the current plate, the welded portion of the current collector plate and its surroundings Measures are taken such as forming the wall relatively thinner than the other parts of the current collector plate and / or forming a groove (notch) in advance at a site to be broken.

  By the way, a sealed secondary battery used as a drive power source for a vehicle such as an electric vehicle or a hybrid vehicle (including a plug-in hybrid vehicle) has a high output and a large capacity (typical) for further enhancement of performance. Requires a battery having an hourly rate capacity of 5 Ah or more, for example, 5 to 20 Ah or 20 Ah or more (for example, 20 to 30 Ah). For this reason, charging / discharging at a high rate that is incomparable with a battery used as a power source for a personal computer or a portable terminal (that is, a consumer product) is required.

  However, when charging / discharging at a higher rate than that of a conventional secondary battery for vehicle driving power is required, in a sealed secondary battery having a current interruption mechanism having the above-described configuration, at the time of high-rate charging / discharging. However, it is necessary to construct a current interruption mechanism so that it is maintained normally and does not perform unexpected operations. For example, as described above, the thin wall formed on the current collector plate in order to quickly reverse and deform the current cutoff valve (reverse plate) at the predetermined case internal pressure (gas pressure) to break a part of the current collector plate A portion or a portion in which a groove (notch) is formed is formed such that the cross-sectional area of the portion is smaller than the cross-sectional area of a relatively thick portion around the portion. In particular, when a groove is further provided in the thin portion, the cross-sectional area of the groove forming portion is further reduced. When a large current flows through such a small cross-sectional area during high-rate charging / discharging, the part generates heat due to the generated Joule heat, and if the heat generation is excessive, the part may be melted due to overheating. There is. Such fusing is not preferable because it causes current interruption.

  The present invention has been made in view of such points, and the object of the present invention is to prevent the current collector plate from fusing due to the Joule heat even during high-rate charge / discharge associated with higher output of the battery, and a predetermined It is an object of the present invention to provide a sealed secondary battery having a highly reliable current interrupting mechanism that realizes current interrupting accurately when a case internal pressure (gas pressure) occurs.

  In order to achieve the above object, a sealed secondary battery is provided according to the present invention. That is, the sealed secondary battery disclosed herein includes an electrode body including a positive electrode and a negative electrode, a battery case that houses the electrode body, and a positive electrode and a negative electrode of the electrode body that are provided on the outer surface of the battery case, respectively. A sealed secondary battery comprising a positive electrode terminal and a negative electrode terminal that are electrically connected, and a current interrupting mechanism that interrupts current when the internal pressure in the case rises above a predetermined level. The current cutoff mechanism includes a current cutoff valve electrically connected to either the positive or negative terminal between the positive electrode of the electrode body and the positive electrode terminal or between the negative electrode of the electrode body and the negative electrode terminal. A rectangular plate-shaped current collector plate electrically connected to either the positive or negative electrode of the electrode body. The rectangular plate-shaped current collector plate is composed of a central thin portion formed relatively thin and a thick portion formed relatively thick around the central thin portion, In addition, a breaking groove is formed in an annular shape with a predetermined diameter inside the central thin portion. A part of the current cutoff valve is joined to the central thin portion of the current collector plate inside the annular groove so as to be energized, and when the internal pressure in the case rises above a predetermined level, The current shut-off valve is deformed in a direction away from the current collector plate by the internal pressure, and the central thin portion of the current collector plate is broken at the annular groove portion. The current cut-off valve with is separated and the current cut-off is realized. A groove that is recessed from the surface of the thick part is formed on at least the surface of the thick part that faces the electrode body.

The current interruption mechanism provided in the sealed secondary battery disclosed herein is composed of the rectangular plate-shaped current collector plate and the current cutoff valve configured as described above as main components, and the current collector plate is thick. A groove portion that is recessed from the surface of the thick portion is formed on at least the surface of the portion facing the electrode body.
In the sealed secondary battery having such a configuration, the current cutoff valve can be rapidly deformed at a predetermined case internal pressure (gas pressure) to partially break the current collector plate. Further, the groove formed on the surface of the thick part of the current collector plate increases the surface area of the current collector plate and improves the heat dissipation of the current collector. For this reason, when a large current flows, such as during high-rate charging / discharging, Joule heat can be effectively dissipated in the thick part of the current collector, and Joule heat transmitted to the breaking annular groove Can be reduced. This makes it difficult for the fractured annular groove to be melted by Joule heat. As described above, the reliability of the current interrupt mechanism is improved in response to the high rate charge / discharge required for high output of the battery, and a higher quality sealed secondary battery (for example, a sealed lithium secondary battery) is provided. Can do.

In a preferred aspect of the sealed secondary battery disclosed herein, an insulating member is disposed in a part between the current cutoff valve and the current collector plate, and the groove portion is formed of the thick portion. It is formed in the surface which opposes the said insulating member among the surfaces of this.
According to this structure, since the surface area of a current collecting plate becomes larger, the heat dissipation of a current collector can be further improved. For this reason, the Joule heat transmitted to the annular groove for breaking can be further reduced, and the annular groove for breaking is hardly melted by the Joule heat.

In another preferred embodiment of the sealed secondary battery disclosed herein, the diameter of the annular groove is 4 mm or more (typically 4 mm or more and 6 mm or less).
By providing an annular groove with a diameter of such a size, the accuracy of the operation of the current cutoff valve (that is, the breakage of the current collector plate) at the predetermined case internal pressure (gas pressure) and the improvement of the heat resistance are at a high level. Both can be achieved.

  Further, according to the present invention, a preferred battery that can achieve both high accuracy in the accuracy of the operation of the current cutoff valve (that is, the breakage of the current collector plate) at the predetermined case internal pressure (gas pressure) and the improvement in heat resistance. As a form, the electrode body is a flat wound electrode body obtained by winding the long sheet-like positive electrode and the long sheet-like negative electrode together with a long sheet-like separator, and the battery case is A so-called square lithium secondary battery or other sealed secondary battery, characterized in that it is formed in a flat square shape that accommodates the wound electrode body corresponding to the shape of the wound electrode body. Can be mentioned.

Further, according to the present invention, any one of the sealed secondary batteries disclosed herein is a single battery, and the single batteries are electrically connected to each other (typically connected in series). 80) is provided.
The assembled battery having such a configuration is excellent in resistance to heat blowing (heat resistance) while maintaining the reliability of the current interruption mechanism of the unit cell constituting the battery, and therefore, as a power source for driving a vehicle such as an electric vehicle or a hybrid vehicle. Is preferred.
Further, the present invention provides a vehicle such as a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), or an electric vehicle (EV) that includes any of the sealed secondary batteries or the assembled batteries disclosed herein as a driving power source. I will provide a.

1 is a perspective view schematically showing an outer shape of a sealed lithium secondary battery (lithium ion battery) according to an embodiment. It is a figure which shows typically the structure of the electrical power collector in the sealed lithium secondary battery which concerns on one Embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, schematically showing the configuration and state (before current interruption) of a current interruption mechanism provided on the positive electrode side of the sealed lithium secondary battery according to one embodiment. It is. It is sectional drawing which shows typically the structure and state (after electric current interruption) of the electric current interruption mechanism provided in the positive electrode side of the sealed lithium secondary battery which concerns on one Embodiment. It is a perspective view which shows the structure of the assembled battery which concerns on one Embodiment. It is a side view which shows typically the vehicle (automobile) provided with the assembled battery which concerns on one Embodiment.

  In the present specification, the “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged / discharged by movement of charges accompanying the lithium ions between the positive and negative electrodes. A secondary battery generally called a lithium ion battery (or a lithium ion secondary battery) is a typical example included in the lithium secondary battery in this specification. Further, in this specification, the “active material” refers to a substance (compound) involved in power storage on the positive electrode side or the negative electrode side. That is, it refers to a substance that is involved in the insertion and extraction of electrons during battery charge / discharge.

Hereinafter, a preferred embodiment of a lithium secondary battery (lithium ion battery) 10 will be described as an example of a sealed secondary battery disclosed herein with reference to the drawings. Although not intended to be particularly limited, hereinafter, a wound type electrode body (hereinafter referred to as a “wound electrode body”) and a non-aqueous electrolyte are accommodated in a rectangular (that is, a rectangular box shape) case. A lithium ion battery having the above-described form will be described as an example. The dimensional relationship (length, width, thickness, etc.) in each figure does not reflect the actual dimensional relationship. Further, members / parts having the same action are denoted by the same reference numerals, and redundant description is omitted or simplified.
Note that the present invention is not limited to a lithium secondary battery (typically a lithium ion battery having a nonaqueous electrolyte) as long as it has a current interruption mechanism having a configuration disclosed herein, The present invention can also be applied to nickel metal hydride batteries and other secondary batteries.

In the lithium ion battery 10 according to the present embodiment, the flat wound electrode body 50 as shown in FIG. 2 has a flat corner corresponding to the shape of the wound electrode body 50 together with a liquid electrolyte (electrolyte) not shown. The battery is configured to be housed in a battery case (that is, an exterior container) 12 (see FIG. 1) having a shape.
The battery case 12 has a box-shaped (that is, a bottomed rectangular parallelepiped) case body 14 having an opening at one end (corresponding to the upper end in a normal use state of the battery 10), and is attached to the opening. It is comprised from the sealing board (lid body) 16 which consists of a rectangular-shaped plate member which plugs up an opening part. The sealing plate (lid body) 16 is welded to the peripheral edge of the opening of the case body 14, so that a pair of case wide surfaces facing the wide surface of the flat wound electrode body 50 and the case wide surface are adjacent to each other. A battery case 12 having a hexahedron-shaped sealed structure with four rectangular case surfaces (that is, one of the rectangular case upper surfaces is constituted by the sealing plate 16) is formed.
Although it does not restrict | limit in particular, As a suitable size of the hexahedron shape case of this kind of square battery, the length of the long side of the case main body 14 and the sealing board 16: about 80-200 mm (for example, 100-150 mm), a case The length on the short side of the main body 14 and the sealing plate 16 (that is, the thickness of the case 12): about 8 to 25 mm (for example, 10 to 20 mm), and the height of the case 12: about 70 to 150 mm can be exemplified.

The material of case 12 should just be the same as what is used with the conventional sealed battery, and there is no restriction | limiting in particular. A case 12 mainly composed of a metal material that is lightweight and has good thermal conductivity is preferable. Examples of such a metal material include aluminum, stainless steel, nickel-plated steel, and the like. The case 12 (the case main body 14 and the sealing plate 16) according to the present embodiment is made of aluminum or an alloy mainly composed of aluminum.
Further, the thicknesses of the case body 14 and the sealing plate 16 are not particularly limited, but when a sealed battery for a vehicle driving power source is configured, about 0.3 mm to 2 mm is appropriate, and about 0.5 mm to 1 mm is preferable. .

As shown in FIG. 1, a positive electrode external terminal 20 and a negative electrode external terminal 18 for external connection are formed on the sealing plate 16. These positive and negative external terminals 18 and 20 can be fitted with a terminal plate or an external connection terminal having an appropriate shape according to the usage pattern of the lithium ion battery 10 according to this embodiment.
Between the positive and negative external terminals 18 and 20 of the sealing plate 16, the internal pressure is released when the internal pressure of the case 12 rises to a predetermined level (for example, a set valve opening pressure of about 0.3 to 1.0 MPa). A thin safety valve 40 configured and a liquid injection port 42 (FIG. 1 shows a state where the liquid injection port 42 is sealed and masked by a sealing material 43 after liquid injection).

  As shown in FIG. 2, the wound electrode body 50 has a long sheet-like positive electrode (positive electrode sheet) 52 and a long length (not shown) similar to the positive electrode sheet 52, similar to a wound electrode body of a normal lithium ion battery. A sheet-like negative electrode (negative electrode sheet) is laminated together with a total of two long sheet-like separators (separator sheets) 54 and wound in the longitudinal direction, and then the obtained wound body is crushed from the side direction and abducted. It is produced by. Specifically, the positive electrode sheet 52 and the negative electrode sheet are slightly shifted in the width direction so that one end in the width direction of either the positive or negative sheet protrudes from one end and the other end in the width direction of the separator sheet 54. It is wound in the state that was done. As a result, one end of the wound electrode body 50 in the winding axis direction and one end in the width direction of the positive electrode sheet 52 and the negative electrode sheet respectively are wound core portions 55 (that is, the positive electrode sheet and the negative electrode sheet). A portion protruding outward from a portion where the separator sheet is wound tightly is formed.

FIG. 2 shows a protruding portion 52 </ b> A of the positive electrode sheet 52, and the protruding portion 52 </ b> A of the positive electrode sheet 52 is interposed via a positive electrode current collecting tab 60 and a positive electrode internal terminal 70 disposed inside the case 12. Thus, the external connection positive electrode external terminal 20 is electrically connected. Similarly, the negative electrode side (not shown) is also electrically connected to the negative external terminal 18 for external connection via a negative electrode current collecting tab and a negative electrode internal terminal (not shown) arranged inside the case 12.
In the lithium ion battery 10 according to the present embodiment, the current interrupt mechanism 80 is configured by a part of the positive external terminal 20 and a part of the positive internal terminal 70 as shown in FIG. The current interruption mechanism 80 will be described later.

The material and the member itself constituting the wound electrode body 50 may be the same as those of the electrode body provided in the conventional lithium ion battery, and are not particularly limited. For example, the positive electrode sheet 52 may have a configuration in which a positive electrode active material layer is formed on a long positive electrode current collector (for example, an aluminum foil). As the positive electrode active material used for forming this positive electrode active material layer, one or two or more materials conventionally used in lithium ion batteries can be used without particular limitation. As a preferred example, an oxide containing lithium and a transition metal element as constituent metal elements such as lithium nickel oxide (for example, LiNiO ₂ ), lithium cobalt oxide (for example, LiCoO ₂ ), and lithium manganese oxide (for example, LiMn ₂ O ₄ ). And a phosphate containing lithium and a transition metal element as constituent metal elements, such as lithium oxide (lithium transition metal oxide), lithium manganese phosphate (LiMnPO ₄ ), and lithium iron phosphate (LiFePO ₄ ).
The negative electrode sheet may have a configuration in which a negative electrode active material layer is formed on a long negative electrode current collector (for example, copper foil). As the negative electrode active material used for forming this negative electrode active material layer, one or two or more materials conventionally used in lithium ion batteries can be used without particular limitation. Preferable examples include carbon-based materials such as graphite carbon and amorphous carbon, lithium transition metal oxides, lithium transition metal nitrides, and the like. Moreover, as a suitable example of the said separator sheet, what was comprised with porous polyolefin resin is mentioned.

As the liquid electrolyte (electrolytic solution), the same non-aqueous electrolytic solution conventionally used in lithium ion batteries can be used without particular limitation. Such a nonaqueous electrolytic solution typically has a composition in which a supporting salt is contained in a suitable nonaqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolane, and the like. One kind or two or more kinds selected from the group can be used. Examples of the supporting salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _{3 and the} like. Lithium salts can be used. As an example, a nonaqueous electrolytic solution in which LiPF ₆ is contained at a concentration of about 1 mol / L in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a volume ratio of 1: 1) can be mentioned. A solid or gel electrolyte may be used instead of the electrolytic solution.

Hereinafter, the current interrupt mechanism 80 will be described in detail with reference to the drawings. First, the internal configuration of the positive electrode external terminal 20 will be described.
As shown in FIG. 2, a positive electrode current collecting tab 60 made of aluminum or an alloy mainly composed of aluminum is connected to the positive electrode protruding portion 52A protruding from one end of the wound electrode body 50 in the winding axis direction. . A positive electrode internal terminal 70 made of aluminum or an aluminum-based alloy is formed so as to extend upward (that is, in the direction of the sealing plate 16) from the positive electrode current collecting tab 60. The positive electrode internal terminal 70 is a rectangular plate-shaped (typically rectangular plate-shaped) current collector body, that is, a current collector plate 72, which is disposed in proximity to the inner surface side of the sealing plate 16 and substantially parallel to the inner surface. The current collecting plate 72 and the positive current collecting tab 60 are configured by an arm-shaped connecting portion 71 that connects the current collecting plate 72 and the positive current collecting tab 60.
The current collecting plate 72 is composed of a central thin portion 74 to which a part (central recess 30A) of a reversing plate (current cutoff valve) 30 described later is welded and a relatively thick thick portion 78 around the central thin portion 74. . The central thin portion is typically formed in a circular or rectangular shape. Further, as shown in FIG. 2, gas flow holes 74 </ b> A and 78 </ b> A are formed at a central portion of the central thin portion 74 and a plurality of locations (two locations in the present embodiment) of the thick portion 78. Further, as shown in FIG. 3, an annular groove (notch) 79 for breaking is formed in a ring shape with a predetermined diameter inside the central thin portion 74.

  As shown in FIG. 3, a plurality of groove portions 90 that are recessed from the thick portion 78 are formed on the surface of the thick portion 78 of the current collector plate 72. The groove part 90 is formed on the surface of the thick part 78 facing the wound electrode body 50. The groove portion 90 is formed on the surface of the thick portion 78 facing the insulating holder 32 described later. The groove portion 90 formed on the surface facing the insulating holder 32 is formed so as to continue from one side of the current collector plate 72 toward the other side. For this reason, even if the insulating holder 32 is disposed above the current collector plate 72, air can be convected along the groove portion 90 formed on the surface facing the insulating holder 32. As shown in FIG. 2, the plurality of groove portions 90 according to the present embodiment are formed in parallel along the long side of the current collector plate 72. In addition, as long as the groove part 90 is formed in the surface of the thick part 78 of the current collecting plate 72, the shape and direction in particular are not restrict | limited. For example, the groove portions 90 may be formed with a predetermined interval, or the groove portion 90 may be formed in a zigzag shape in a cross-sectional view. Further, the current collector plate 72 may be formed in parallel along the short side. By forming the plurality of groove portions 90 in the thick portion 78 of the current collector plate 72, the surface area of the current collector plate 72 is increased and the heat dissipation of the current collector plate 72 is improved. As a result, when a large current flows, such as during high-rate charge / discharge, Joule heat can be effectively radiated in the thick portion 78 of the current collector plate 72, so the annular groove 79 for fracture is melted. It becomes difficult. Further, since the non-aqueous electrolyte is easily adsorbed and held in the groove 90, Joule heat can be radiated from the thick portion 78 of the current collector plate 72 to the non-aqueous electrolyte.

Although not particularly limited, in the case of a battery used as a vehicle driving power source, the rectangular plate-shaped current collector plate 72 typically has a short side length (short diameter) of about 6 mm to 15 mm. The length (major axis) of the long side of the current collector plate 72 is typically defined to be about 2 to 5 times the minor axis.
Moreover, the thickness of the thick part 78 is typically 2 mm or less (for example, 0.4 mm to 2 mm), and preferably 1 mm or less (for example, 0.5 mm to 1 mm). The thickness of the central thin portion 74 is typically 0.2 mm or less (for example, 0.05 mm to 0.2 mm), and preferably 0.15 mm or less (for example, 0.08 mm to 0.15 mm).
The depth of the groove portion 90 formed in the thick portion 78 is suitably such that the thickness of the remaining portion in the groove portion 90 is at least about 0.05 mm, and is 0.1 mm or more (for example, 0.1 mm to 0 mm). About 5 mm). If the thickness of the remaining portion is too small, the surface area of the current collector plate 72 is increased, but the fusing resistance becomes too low, which is not preferable.

The size of the central thin portion 74 is not particularly limited, but is a length corresponding to 40 to 70% of the length of the minor axis of the current collector plate 72 (for example, when the minor axis of the current collector plate 72 is 8 mm). It is appropriate to form a circular or square shape having a diameter of 3.2 mm to 5.6 mm.
The diameter of the annular groove 79 is preferably 4 mm or more (typically 4 mm or more and 6 mm or less). In addition, as for the formation position of the annular groove 79, it is appropriate that the distance between the thick portion 78 and the annular groove 79 is 0.5 mm or less from the viewpoint of improving the resistance (heat resistance) against fusing. 2 to 0.4 mm (for example, about 0.3 mm ± 0.05 mm) is preferable.
Further, the depth of cut of the annular groove 79 is suitably at least about 0.025 mm, and the thickness of the remaining portion in the annular groove 79 is 0.03 mm or more (for example, about 0.03 mm to 0.08 mm). Preferably). If the thickness of the remaining portion is too small, the fusing resistance becomes too low, which is not preferable. Conversely, if the thickness of the remaining portion is too large, the current collector plate is difficult to break when a predetermined internal pressure is generated. Absent.

As shown in FIG. 3, the positive electrode external terminal 20 according to the present embodiment is mounted in a positive electrode mounting hole 16 </ b> A formed in advance on the sealing plate 16 on the outer surface side (upward direction in FIG. 3) of the sealing plate 16. A cylindrical connection terminal 22 and a gasket 24 sandwiched between the cylindrical connection terminal 22 and the sealing plate 16 (periphery of the positive electrode mounting hole 16A) are provided. A rubber terminal plug 23 is sealed in the through hole 22B of the cylindrical connection terminal 22.
Further, the positive external terminal 20 according to the present embodiment is a rectangular cap-shaped synthetic resin in which insertion holes into which the cylindrical connection terminals 22 can be inserted are formed on the inner surface side (downward in FIG. 3) of the sealing plate 16. An insulating plate 26 made of metal and a sealing member tab 28 made of metal are provided.
More specifically, as shown in FIG. 3, the cylindrical connection terminals 22 electrically connected to the positive electrode internal terminal 70 are respectively formed on the gasket 24, the sealing plate 16, the insulating plate 26, and the sealing body tab 28. The members 22, 24, 16, 26, and 28 are integrally fixed by being inserted into the holes and caulking the tip 22 C as shown in the figure.

Further, the reversing plate 30 functioning as a rectangular plate-shaped current cutoff valve is welded to the edge of the rectangular cap-shaped sealing body tab 28, and the current collector plate 72 and the reversing plate 30 have peripheral portions. An insulating holder 32 made of a synthetic resin is disposed for the purpose of positioning the current collecting plate 72 and the reversing plate 30 and electrically insulating the peripheral portion.
Further, the central portion of the rectangular plate-like reversing plate 30 is recessed so as to contact the central thin portion 74 of the current collector plate 72 through a hole formed in the central portion of the corresponding insulating holder 32. The central recess 30A of 30 is joined to the inside of the annular groove 79 of the central thin portion 74 of the current collector plate 72 by laser welding or ultrasonic welding. In other words, in the central thin portion 74 of the current collecting plate 72 of the positive electrode internal terminal 70, the fracture annular groove 79 exists around the joint portion of the central recess 30 </ b> A of the reversing plate 30.
With the above configuration, the positive electrode sheet 52 is electrically connected to the cylindrical connection terminal 22 through the positive electrode protruding portion 52A, the positive electrode current collecting tab 60, the positive electrode internal terminal 70, the reversing plate 30, and the sealing body tab 28.

  When the pressure (gas pressure) in the battery case 12 increases to a predetermined value or more, the reversing plate 30 bends and deforms toward the cylindrical connection terminal 22 (typically reverses and deforms toward the cylindrical connection terminal 22). ) Is formed. Further, since the current collecting plate 72 is welded to the central recess 30A of the reversing plate 30, when the pressure in the case 12 exceeds a predetermined value and the reversing plate 30 is deformed as described above, the current collecting plate is accordingly generated. The thin portion 74 of the plate 72 is broken at the annular groove 79. Thereby, as shown in FIG. 4, the electrical connection between the reversing plate 30 and the current collecting plate 72 is interrupted. In addition, although the electric current interruption mechanism 80 which concerns on this embodiment is provided in the positive electrode internal terminal 70 side, it is not restricted to this aspect, You may provide in the negative electrode internal terminal (not shown) side.

  Hereinafter, some specific test examples relating to the current collector provided by the present invention will be introduced, but the current collector provided by the present invention is intended to be limited to the form introduced below. is not.

<Test example: resistance evaluation of current collector>
A total of two types (samples 1 and 2) of rectangular plate-shaped aluminum current collector plates 72, each size of which was designed as shown in Table 1 below, were produced. The major axis size of the current collector plate of each sample was 2.5 times the minor axis size. On the other hand, an inversion plate 30 having a rectangular shape of 8 mm (short diameter) × 20 mm (long diameter) as shown in FIG. 3 and having a thickness of about 0.3 mm to 0.5 mm was prepared. In the current collector plate 72 of Sample 1, a plurality of groove portions 90 that are recessed from the surface of the thick portion 78 are formed on the surface of the thick portion 78.
Thus, the central recess 30 </ b> A of the reversing plate 30 was laser welded to the peripheral portion of the gas flow hole 74 </ b> A that is the center of the central thin portion 74 and inside the annular groove 79.

  The resistance (heat resistance) against fusing was evaluated using the joined body of the current collecting plate and the reversing plate of each sample. Specifically, for each sample joined body, a large capacity current (1000A in this case) was passed between the current collector plate and the reversing plate, and the annular groove part was melted by the Joule heat generated at that time. Time (seconds) was measured. The results are shown in Table 1.

  As shown in Table 1, the current collector plate 72 of Sample 1 in which a plurality of groove portions 90 are formed on the surface of the thick wall portion 78 is fused as compared with the current collector plate 72 of Sample 2 in which the groove portions 90 are not formed. It was confirmed that the time to do this was extended by about 30%.

  As described above, according to the present invention, a sealed secondary battery (typically a lithium secondary battery having a square outer shape or other sealed secondary battery having a current interruption mechanism using a current collector plate disclosed herein is used. Battery). Since such a current collector has a large surface area and excellent heat dissipation, it is excellent in resistance to fusing (heat resistance). For this reason, it is suitable as a power source for driving a vehicle that requires high-rate charging / discharging with high output. Therefore, the present invention also provides an assembled battery 100 as schematically shown in FIG.

Specifically, as shown in FIG. 5, a sealed secondary battery (typically including a current interrupting mechanism (see FIGS. 2 to 4 described above)) constructed using the current collector disclosed herein (typically, Is a square-shaped lithium secondary battery 10 as shown in the figure, and a plurality of the battery cells 10 (four in the illustrated embodiment, but not limited to this, for example, 40 to 80). .) It is arranged in a predetermined direction. Typically, the unit cells 10 are connected in series as illustrated. Specifically, the positive electrode external terminal 20 that is electrically connected to the positive electrode of the electrode body accommodated in the case 12 and the negative electrode are electrically connected to the upper surface (that is, the sealing plate) 16 of the battery case 12 of each unit cell 10. Negative external terminals 18 are provided respectively. Then, between the adjacent unit cells 10, one positive external terminal 20 and the other negative external terminal 18 are electrically connected by an appropriate connector 92. End plates 96 are arranged on both outer sides of the arranged unit cell groups 11, and clamping beams are arranged along the arrangement direction on both side surfaces of the unit cell group 11 so as to bridge the pair of end plates 96, 96. A material 98 is attached, and each end of the beam material 98 can be fastened and fixed to the end plate 96 with screws 99. In this way, by connecting the single cells 10 in series and restraining (fixing) them, an assembled battery 100 suitable as a driving power source for a vehicle having a desired voltage is constructed.
It is to be noted that a spacing sheet 94 having a predetermined shape is disposed between the plurality of single cells 10 that are typically arranged in a predetermined direction. The spacing sheet 94 is made of a material that can function as a heat radiating member for radiating the heat generated in each unit cell 10 during use (for example, a metal having a good thermal conductivity, a lightweight, hard polypropylene, or other synthetic resin). ) And / or shape.

  In addition, as shown in FIG. 6, the present invention has a high output and a large capacity (typically a 1 hour rate capacity of 5 Ah) provided with a current interrupting mechanism constructed by using the current collector disclosed herein. As described above, for example, a group in which a sealed secondary battery (typically a square-shaped sealed lithium secondary battery) having a capacity of 5 to 20 Ah or 20 Ah or more (for example, 20 to 30 Ah) is used as a single battery. It is possible to provide a vehicle 1 (typically, an automobile including a drive motor such as an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, and a fuel cell vehicle) including the battery 100 as a driving power source.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1 Vehicle 10 Lithium secondary battery (lithium ion battery)
12 Battery case 14 Case body 16 Sealing plate (lid)
18 Negative External Terminal 20 Positive External Terminal 22 Cylindrical Connection Terminal 22B Through Hole 22C Tip 24 Gasket 26 Insulation Plate 28 Sealing Body Tab 30 Inversion Plate (Current Cutoff Valve)
30A Central recessed part 32 Insulation holder 50 Winding electrode body 52 Positive electrode sheet 54 Separator sheet 55 Winding core part 60 Positive electrode current collection tab 70 Positive electrode internal terminal 71 Connection part (arm part)
72 Current Collector Plate 74 Center Thin Wall 74A Gas Flow Hole 78 Thick Wall 78A Gas Flow Hole 79 Annular Groove (Notch)
80 Current interruption mechanism 90 Groove part 100 Battery pack

Claims (6)

An electrode body comprising a positive electrode and a negative electrode;
A battery case that houses the electrode body;
A positive electrode terminal and a negative electrode terminal that are provided on the outer surface of the battery case and are electrically connected to the positive electrode and the negative electrode of the electrode body, respectively;
A sealed secondary battery comprising a current interrupting mechanism that interrupts current when the internal pressure in the case rises above a predetermined level,
The current cutoff mechanism includes a current cutoff valve electrically connected to either the positive or negative terminal between the positive electrode of the electrode body and the positive electrode terminal or between the negative electrode of the electrode body and the negative electrode terminal. A rectangular plate-shaped current collector plate electrically connected to either the positive or negative electrode of the electrode body,
The rectangular plate-shaped current collector plate is composed of a central thin portion formed relatively thin and a thick portion formed relatively thick around the central thin portion, In addition, a breaking groove is formed in an annular shape with a predetermined diameter inside the thin center portion,
A part of the current cutoff valve is joined to the central thin part of the current collector plate inside the annular groove so as to be energized,
When the internal pressure in the case rises above a predetermined level, the current shut-off valve is deformed in a direction away from the current collector plate by the internal pressure, and the central thin portion of the current collector plate at the annular groove portion Is configured so that the current cut-off valve with the broken central thin portion is separated from the current collector plate to realize the current cut-off,
A sealed secondary battery, wherein a groove portion recessed from the surface of the thick portion is formed on at least a surface of the thick portion facing the electrode body.   An insulating member is disposed between a portion of the current cutoff valve and the current collector plate, and the groove is formed on a surface of the thick portion facing the insulating member. The sealed secondary battery according to claim 1, wherein:   The sealed secondary battery according to claim 1, wherein the annular groove has a diameter of 4 mm or more. The electrode body is a flat wound electrode body formed by winding the long sheet-like positive electrode and the long sheet-like negative electrode together with a long sheet-like separator,
The said battery case is formed in the flat square shape which accommodates this winding electrode body corresponding to the shape of this winding electrode body, It is any one of Claims 1-3 characterized by the above-mentioned. The sealed secondary battery described.   An assembled battery comprising the sealed secondary battery according to any one of claims 1 to 4 as a single battery, and a plurality of the single batteries that are electrically connected to each other.   A vehicle provided with the sealed secondary battery according to any one of claims 1 to 4 or the assembled battery according to claim 5 as a driving power source.

Images