JP2013140818A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which inhibits contact failure between a collector and a terminal when an impact such as dropping is applied and achieves good quality and good sealability of a case.SOLUTION: At a center part of a lid of a battery, a negative electrode terminal, having a T shape in a cross sectional view, penetrates through the lid being enclosed by a gasket. An insulator contacts with a lower end part of the gasket, and a plate like collector is housed in the insulator. The collector is provided with an insulation hole, and the terminal is inserted into the insertion hole thereby being joined to the terminal. The insertion hole forms a polygonal shape, and a portion of the terminal which is inserted into the insertion hole forms the same polygonal shape as the insertion hole in a plane view.

Description

The present invention relates to a battery in which a battery element is accommodated in a case and the opening of the case is closed by a lid portion.

In recent years, along with the downsizing and diversification of portable electronic devices such as video cameras, mobile computers, mobile phones, etc., the battery as the power source is smaller and lighter, has high energy density, and storage stability. Therefore, there is a strong demand for the development of a secondary battery that is highly reliable and that can be repeatedly charged and discharged for a long period of time.
As a secondary battery that satisfies these requirements, a non-aqueous electrolyte secondary battery including a non-aqueous electrolyte can be given.

A typical example of the non-aqueous electrolyte secondary battery is a lithium ion secondary battery. A lithium ion secondary battery includes a negative electrode made of an active material capable of occluding and releasing lithium ions, a positive electrode made of transition metal oxide, fluorinated graphite, a composite oxide of lithium and transition metal, and the like. A water electrolyte. The non-aqueous electrolyte is formed by mixing an aprotic organic solvent with a lithium salt such as LiBF ₄ , LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , Li ₂ SiF ₆ .

In the lithium ion secondary battery, the flat wound electrode group in which the positive electrode and the negative electrode are wound via a separator is accommodated in a case made of aluminum or an aluminum alloy, and the case opening is made of aluminum or aluminum. It is closed by an aluminum alloy lid.

FIG. 12 is a perspective view showing a state in which the lid portion 53 of the conventional lithium ion secondary battery is viewed from the back side.
A central portion of the lid portion 53 has a flat head portion 54a and a cylindrical leg portion 54b (see FIG. 13), and a negative electrode terminal 54 having a T-shape in cross-section is connected to the negative electrode terminal 54. Except for the surface, it is provided so as to penetrate the lid portion 53 while being surrounded by a gasket 55 made of synthetic resin.
A synthetic resin insulator 56 is provided in contact with the lower end of the gasket 55 so as to extend toward the one end of the lid 53 along the back surface of the lid 53. A current collector 57 made of copper and having a plate shape is accommodated in the recess of the insulator 56. A negative electrode lead connected to the negative electrode plate of the electrode group is connected to a tab 57 b that hangs down from the current collector 57.

FIG. 13 is a perspective view showing a state in which the end of the negative electrode terminal 54 is crimped and joined to the current collector 57. In the drawing, the lid 53, the gasket 55, and the insulator 56 are omitted.
The negative electrode terminal 54 is joined to the current collector 57 by inserting the negative electrode terminal 54 through the insertion hole 57a (FIG. 13A) and crimping the end of the leg portion 54b (curling press). The crimping portion 54 c is electrically connected to the current collector 57 (FIG. 13B), and is fixed to the lid portion 53 through the current collector 57 and the insulator 56.
As shown in FIG. 13B, the contact state between the substantially disc-shaped caulking portion 54c and the circular insertion hole 57a is weak against rotational stress with respect to the central axis of the insertion hole 57a. Therefore, when the lithium ion secondary battery falls or receives an impact, the crimping portion 54c rotates, the contact state between the negative electrode terminal 54 and the current collector 57 is deteriorated, and the connection resistance is increased. There was a problem that there was.

In order to solve this problem, the portion marked with x shown in FIG. 13B may be welded. However, the problem that the process becomes complicated due to the addition of the welding process, and a part of the insulator 56 melts due to the thermal energy of the welding, and the sealing performance of the lid portion 53 by the insulator 56 deteriorates. There was a problem that water electrolyte might leak.

In Patent Document 1, a rivet is passed through a battery lid with a gasket interposed, and the rivet is fastened to the lid via a gasket and a washer on the inner surface side of the lid. The invention of the battery which provided the projection part in the peripheral part of this rivet through-hole, or the inner surface of the head part of a rivet is disclosed. With this configuration, leakage of the electrolyte is prevented.

In Patent Document 2, an electrode lead plate is disposed on the outer surface of the lid portion via an insulator, the electrode lead-out pin is passed through the lid portion, and the outer end portion of the electrode lead-out pin is crimped to the electrode lead plate. And a battery invention in which an annular protrusion is provided on the peripheral edge of the through hole of the electrode lead-out plate is disclosed. With this configuration, the conductive contact between the electrode lead-out pin and the electrode lead-out plate is improved.

In Patent Document 3, the distance between the boundary between the leg and the head and the longitudinal end of the head is reduced by forming the head and the leg of the rivet terminal into an oval shape in plan view. Then, when the leg portion is crimped to the inner surface of the lid portion via the lead member, the end portion is not lifted, and a battery invention in which the occurrence of poor welding is suppressed when the terminal cap is welded to the head portion is disclosed. ing.

In Patent Document 4, a rivet terminal composed of a head and a leg is passed through the lid, and the leg is caulked with a first washer on the outer surface side of the lid, and the rivet terminal on the inner surface side of the lid. An invention of a battery is disclosed in which the head is fixed through two washers, and a contact portion between the head and the second washer is welded. With this configuration, the occurrence of contact failure is suppressed.
Japanese Utility Model Publication No. 5-31108 JP 2003-45404 A Japanese Utility Model Publication No. 7-27051 JP-A-6-231740

In the battery of Patent Document 1 described above, the rotation of the rivet is suppressed, but when the battery is dropped or an impact is applied, the contact state between the rivet crimped portion and the washer is distorted, and the contact There was a risk of defects.
In the battery of Patent Document 2, since the protrusion is continuously provided in an annular shape on the periphery of the electrode lead plate, the electrode lead pin is an electrode when the outer end portion of the electrode lead pin is crimped to the electrode lead plate. There is a problem that it is difficult to bite into the drawing plate side, and the electrode lead-out pin is easy to rotate with respect to the annular protrusion, and there is a possibility that contact failure may occur when an impact is applied to the battery.

In the battery of Patent Document 3, the leg portion of the rivet terminal has an oval shape in a plan view, the circumference is long, and the distance from the central axis varies depending on the edge portion of the leg portion. It is difficult to tighten, and there is a possibility that poor contact occurs between the leg portion and the lead member.
In the battery of Patent Document 4, as described above, there is a problem that the process becomes complicated due to the addition of the welding process, and a part of the lid made of synthetic resin is melted by the thermal energy of the welding. There is a possibility that the contact between the lid and the washer is deteriorated, and the sealing performance with respect to the nonaqueous electrolyte is deteriorated.

The present invention has been made in view of such circumstances, and the joint portion between the current collector and the terminal has a rotation suppression structure that suppresses rotation of the terminal without using welding, thereby An object of the present invention is to provide a battery having good quality and hermeticity in which a contact state with a terminal is stabilized and contact resistance is prevented from increasing when a shock such as dropping is applied, and a connection resistance is increased. .

The battery according to claim 1 of the present invention is provided with a terminal penetrating the lid portion of the battery case and an insertion hole, arranged on the inner surface side of the lid portion, and the terminal being inserted through the insertion hole. In a battery comprising a current collector joined to a terminal, and the terminal and the current collector, and an insulator interposed between the lid portion, a joint portion between the current collector and the terminal is: The insertion hole has a polygonal shape, and a portion of the terminal through which the insertion hole is inserted has a polygonal shape that is the same shape as the insertion hole in a plan view.

In the invention of claim 1, as a terminal rotation suppression structure, the hole through which the current collector terminal is inserted is not a round hole, but a polygonal shape, and the portion through which the terminal insertion hole is inserted is an insertion hole in plan view. Because when the terminal is inserted into the current collector and joined to the current collector, the portion through which the terminal insertion hole is inserted cannot rotate relative to the current collector insertion hole. Rotation of is suppressed satisfactorily. Thus, since the junction part of an electrical power collector and a terminal has a rotation suppression structure, when impacts, such as dropping, are applied, it is suppressed that a terminal rotates, and it is suppressed that a contact failure arises.
Further, as in the case of suppressing rotation by welding the joint portion between the current collector and the terminal, the insulating member or the like attached to the lid portion is not deformed, and the sealing performance of the lid portion is ensured.

The battery according to the reference example of the present invention may be configured such that the rotation suppression structure is configured by a notch provided in a peripheral edge portion of the insertion hole of the current collector.

According to this, when the terminal is crimped to the current collector, the deformed portion of the end of the terminal bites into the notch and is locked to the notch, so that the rotation of the terminal is satisfactorily suppressed.

Moreover, the battery according to the reference example of the present invention may be configured such that the rotation suppression structure is configured by a plurality of protrusions provided around the insertion hole of the current collector.

According to this, since the protruding portion is formed discontinuously at the peripheral portion of the insertion hole, the end portion of the terminal bites into the current collector side from the gap between the protruding portions when the terminal is crimped to the current collector. Then, the protruding portion is deformed in a state of biting into the end portion of the terminal, and a crimped portion is formed. Therefore, the end portion is satisfactorily locked to the protruding portion, is in close contact with the current collector, and the rotation of the terminal is well suppressed.

According to the present invention, the junction between the current collector and the terminal has a rotation deterrent structure that tightly contacts the current collector and the terminal and deters rotation of the terminal, so that the contact state is stabilized and the battery falls. For example, when an impact is applied, a contact failure occurs, and an increase in connection resistance is suppressed.
Then, the welding process is not complicated as in the case where the joint between the current collector and the terminal is further welded to suppress rotation, and the insulating member attached to the lid part is deformed. Therefore, the quality and the sealing property of the case are good, and leakage of contents such as non-aqueous electrolyte is suppressed.

It is a perspective view which shows the battery which concerns on the reference form 1 of this invention. It is a perspective view which shows the state which looked at the cover part of the battery which concerns on the reference form 1 of this invention from the back side. It is a partially broken side view which shows the cover part which concerns on the reference form 1 of this invention. It is a perspective view which shows the electrical power collector which concerns on the reference form 1 of this invention. It is a perspective view which shows the state which crimps the edge part of the negative electrode terminal which concerns on the reference form 1 of this invention, and is joined to a collector. It is a longitudinal cross-sectional view which shows the principal part of the cover part which concerns on the reference form 1 of this invention. It is a perspective view which shows the state which penetrates the edge part of the negative electrode terminal which concerns on the reference form 2 of this invention through the penetration hole of a collector. It is a longitudinal cross-sectional view which shows the principal part of the cover part which concerns on the reference form 2 of this invention. It is a perspective view which shows the state which penetrates the edge part of the negative electrode terminal which concerns on the reference form 3 of this invention through the penetration hole of a collector. It is a perspective view which shows the state which penetrates the edge part of the negative electrode terminal which concerns on the reference form 4 of this invention through the penetration hole of a collector. It is a perspective view which shows the state which penetrates the edge part of the negative electrode terminal which concerns on embodiment of this invention to the penetration hole of a collector. It is a perspective view which shows the state which looked at the cover part of the conventional battery from the back side. It is a perspective view which shows the state which crimps the edge part of the negative electrode terminal of the conventional battery, and joins it with a collector.

Hereinafter, the present invention will be specifically described with reference to the drawings based on the drawings showing the embodiments thereof.
Reference Form 1
FIG. 1 is a perspective view showing a lithium ion secondary battery (hereinafter referred to as a battery) 1 according to Reference Embodiment 1 of the present invention, and FIG. 2 is a perspective view showing a state in which a lid portion 3 of the battery 1 is viewed from the back side. FIG. 3 is a partially broken side view showing the lid 3. In FIG. 2, a connecting portion of a recess 32 described later is omitted.

The battery 1 is a flat wound electrode in which a negative electrode plate obtained by applying a negative electrode mixture to a copper current collector and a positive electrode plate obtained by applying a positive electrode mixture to an aluminum current collector are wound through a separator. A group and a non-aqueous electrolyte (not shown) are opened on one side, have a substantially rectangular parallelepiped shape, and are accommodated in a case 2 made of aluminum, and the opening of the case 2 is closed by an aluminum lid 3.
At one end of the lid portion 3, there is a rupture valve 31 that is thinner than the other portions in order to release the pressure when the internal pressure of the battery 1 is abnormally increased and has an oval shape in plan view. Is provided. A concave portion 32 having a rectangular shape in plan view is provided at the other end portion of the lid portion 3, and a protruding portion 33 is provided below the concave portion 32.

A negative electrode terminal 4 having a flat head portion 41 and a cylindrical leg portion 42 in the center portion of the lid portion 3 and having a T-shaped cross-sectional view is synthesized except for the surface of the negative electrode terminal 4. In a state surrounded by the resin gasket 5, it is provided so as to penetrate the lid portion 3. The negative electrode terminal 4 is made of nickel-plated steel and is annealed after processing. The negative electrode terminal 4 may be made of a nickel material. In the battery 1, a portion other than the portion where the negative electrode terminal 4 of the case 2 is provided is a positive electrode (terminal).

A synthetic resin insulator 6 is provided in contact with the lower end of the gasket 5 so as to extend toward the one end of the lid 3 along the back surface of the lid 3. The recess 6 of the insulator 6 is made of copper and accommodates a plate-like current collector 7. A tab 71 is suspended from the current collector 7, and a negative electrode lead connected to the negative electrode plate of the electrode group is connected to the tab 71. The current collector 7 may be made of nickel material or nickel-plated steel material.

The protruding portion 33 is made of aluminum and connected to a plate-like current collector 8. A positive electrode lead connected to the positive electrode plate of the electrode group is connected to a tab 81 suspended from the current collector 8.

FIG. 4 is a perspective view showing the current collector 7.
As shown in FIG. 4, the circular hole-shaped insertion hole 72 provided at one end of the current collector 7 has two locations in the direction that coincides with the longitudinal direction of the current collector 7, and the radius of the insertion hole 72 is substantially the same. Cutouts 72a, 72a having a radius of 1/3 and having a substantially semicircular shape are provided.

FIG. 5 is a perspective view showing a state in which the end of the negative electrode terminal 4 is crimped and joined to the current collector 7, and FIG. 6 is a longitudinal sectional view showing the main part of the lid 3. In FIG. 5, the lid 3, the gasket 5, and the insulator 6 are omitted.
The negative electrode terminal 4 is inserted through the insertion hole 72 (FIG. 5A), and the ends of the leg portions 42 of the negative electrode terminal 4 are caulked to form a crimp portion 43. The negative electrode terminal 4 is connected to the current collector 7. It is fixed (FIG. 5B).
As shown in FIG. 6, when the leg portion 42 is crushed, the deformed portion of the leg portion 42 bites into the notches 72a and 72a and is locked to the notches 72a and 72a. It adheres well to the electric body 7, and the caulking portion 43 is prevented from rotating with respect to the central axis of the insertion hole 72. Moreover, since the leg part 42 is cylindrical, it can crimp uniformly and it is suppressed that a contact failure arises between the electrical power collector 7 and the negative electrode terminal 4 at the time of crimping.

As described above, since the joint portion between the negative electrode terminal 4 and the current collector 7 has a rotation suppression structure, in this reference embodiment, the contact state between the negative electrode terminal 4 and the current collector 7 is stabilized, and the battery 1 is When an impact is applied by dropping or the like, it is suppressed that contact failure occurs between the negative electrode terminal 4 and the current collector 7 and the connection resistance increases.
In addition, it is not necessary to suppress rotation by welding the current collector 7 and the caulking portion 43, the insulator 6 attached to the lid portion 3 is not deformed, and the battery 1 has good quality and It has airtightness.
Note that the number, shape, and size of the notches 72a provided in the insertion hole 72 are not limited to the number, shape, and size described in the present reference embodiment.

Reference form 2
The battery according to the reference form 2 of the present invention has the same configuration as that of the battery 1 according to the reference form 1, and the rotation suppression structure of the joint portion between the negative electrode terminal 14 and the current collector 11 is the rotation suppression structure of the reference form 1. And different.

FIG. 7 is a perspective view showing a state in which the end portion of the negative electrode terminal 14 is inserted into the insertion hole 11a of the current collector 11, and FIG. 8 is a longitudinal sectional view showing a main part of the lid portion of the battery.
As shown in FIG. 7, protrusions 11 b, 11 b,... Are provided around the periphery of the insertion hole 11 a of the current collector 11.
When the end portion of the leg portion 14b of the negative electrode terminal 14 is inserted into the insertion hole 11a and the end portion is crimped to the current collector 11, as shown in FIG. 8, projections 11b and 11b are formed on the deformed portions of the end portion. ,... Bite and the caulking portion 14c is locked to the projecting portions 11b, 11b,..., So that the caulking portion 14c adheres well to the current collector 11 and rotates with respect to the central axis of the insertion hole 11a. To be suppressed. Since the protrusions 11b, 11b,... Are formed discontinuously on the peripheral edge of the insertion hole 11a, when the negative electrode terminal 14 is crimped to the current collector 11, unlike the case where the protrusions are formed annularly, The end of the negative electrode terminal 14 can penetrate deeply into the current collector 11 side, and the rotation suppression effect is high.

In the present embodiment, the contact state between the negative electrode terminal 14 and the current collector 11 is stabilized, and even when an impact is applied to the battery, the negative terminal 14 and the current collector 11 are not affected by the rotation suppression structure described above. The occurrence of poor contact between them is suppressed.

Reference form 3.
The battery according to the reference form 3 of the present invention has the same configuration as that of the battery 1 according to the reference form 1, and has a rotation suppression structure in which the rotation suppression structures of the reference forms 1 and 2 are combined.

FIG. 9 is a perspective view showing a state in which the end of the negative electrode terminal 4 is inserted into the insertion hole 12 a of the current collector 12.
As shown in FIG. 9, the insertion hole 12a of the current collector 12 is provided with substantially semicircular cutouts 12b and 12b, similar to the current collector 7 according to the reference form 1, Semi-annular protrusions 12c and 12c are provided around the notches 12b and 12b so as to face each other.

Since the end portion of the leg portion 42 of the negative electrode terminal 4 is inserted into the insertion hole 12a and the end portion is crimped to the current collector 12, the deformed portion of the end portion is cut. Since the protrusions 12c and 12c bite into the notches 12b and 12b and the deformed portions of the end portions, the caulking part is locked at the notches 12b and 12b and the protrusions 12c and 12c, and the current collector 12 It adheres satisfactorily, and the caulking portion is further effectively prevented from rotating with respect to the central axis of the insertion hole 12.
At this time, since the protrusions 12c and 12c are formed discontinuously at the peripheral edge of the insertion hole 12, when the negative electrode terminal 4 is crimped to the current collector 12, unlike the case where the protrusions are formed in an annular shape. The end of the negative electrode terminal 4 can penetrate deeply into the current collector 12 side.

Since the joint between the negative electrode terminal 4 and the current collector 12 has the above-described rotation suppression structure, in this reference embodiment, the contact state between the negative electrode terminal 4 and the current collector 12 is stabilized, and an impact is applied to the battery. Even in this case, the occurrence of contact failure between the negative electrode terminal 4 and the current collector 12 is suppressed.

Reference form 4.
The battery according to the reference form 4 of the present invention has the same configuration as the battery 1 according to the reference form 1, and the rotation suppression structure of the joint portion between the negative electrode terminal 4 and the current collector 13 is the rotation of the reference forms 1 to 3. Different from deterrent structure.

FIG. 10 is a perspective view showing a state in which the end of the negative electrode terminal 4 is inserted into the insertion hole 13 a of the current collector 13.
As shown in FIG. 10, the insertion hole 13 a of the current collector 13 according to the reference form 4 is not a round hole but has a substantially square shape.
Since it is configured as described above, when the end portion of the leg portion 42 of the negative electrode terminal 4 is inserted into the insertion hole 13a and the end portion is crimped to the current collector 13, the deformed portion of the end portion is inserted. Since it bites into the corner portion of the hole 13a and is locked to the corner portion, it closely adheres to the current collector 13, and the caulking portion is well suppressed from rotating with respect to the central axis of the insertion hole 13. .

Since the joint portion between the negative electrode terminal 4 and the current collector 13 has the above-described rotation suppression structure, in this reference embodiment, the contact state between the negative electrode terminal 4 and the current collector 13 is stabilized, and an impact is applied to the battery. Even in this case, the occurrence of poor contact between the negative electrode terminal 4 and the current collector 13 is suppressed.
In addition, in the said reference form, although demonstrated about the case where the penetration hole 13a has a substantially square shape, it is not limited to this, A penetration hole has other polygonal shapes, such as a regular hexagon and a regular octagon. It may be a thing.
Further, in addition to making the insertion hole 13a into a polygonal shape, a notch is provided in the insertion hole 13a as in the reference mode 1, or a protrusion is provided in the insertion hole 13a as in the reference mode 2. May be.

Embodiment.
The battery according to the embodiment of the present invention has the same configuration as that of the battery 1 according to the reference form 1, and the rotation suppression structure of the joint portion between the negative electrode terminal 15 and the current collector 13 is the rotation of the reference forms 1 to 4. Different from deterrent structure.

FIG. 11 is a perspective view showing a state in which the end of the negative electrode terminal 15 is inserted through the insertion hole 13 a of the current collector 13. In the figure, the same parts as those in FIG.
As shown in FIG. 11, the insertion hole 13a of the current collector 13 according to the embodiment is not a round hole but has a substantially square shape. Moreover, the negative electrode terminal 15 according to the embodiment includes a flat head portion 15a and a leg portion 15b having a substantially square shape that is the same shape as the insertion hole 13a of the current collector 13 in plan view.
Since the end portion of the leg portion 15b of the negative electrode terminal 15 is inserted into the insertion hole 13a and the end portion is joined to the current collector 13, the insertion hole 13a and the leg portion 15b are configured as described above. Since the shape of the plan view is the same, the legs 15b are in close contact with each other, and the leg portion 15b inserted in the substantially square-shaped square hole (insertion hole 13a) and having a substantially square shape in plan view cannot rotate with respect to the square hole. Rotation of the leg portion 15b with respect to the central axis of the insertion hole 13a is suppressed satisfactorily.

Since the joint portion between the negative electrode terminal 15 and the current collector 13 has the above-described rotation restraining structure, in this embodiment, the contact state between the negative electrode terminal 15 and the current collector 13 is stabilized, and the battery has an impact. Even when it is added, the occurrence of poor contact between the negative electrode terminal 15 and the current collector 13 is suppressed.
In the present embodiment, the case where the insertion hole 13a has a substantially square shape and the leg portion 15b of the negative electrode terminal 15 has a substantially square shape in plan view is described, but the present invention is not limited thereto. The legs of the insertion hole and the negative electrode terminal may have other polygonal shapes such as a hexagonal shape and an octagonal shape in plan view.
Further, in addition to making the insertion hole 13a polygonal and the leg 15b polygonal in plan view, the insertion hole 13a is provided with a notch as in the first embodiment, or the insertion is performed in the same manner as in the second embodiment. You may decide to provide a projection part in the hole 13a.

The present invention will be described below together with reference examples using preferred examples. However, the present invention is not limited to the examples, and the present invention is implemented as appropriate without departing from the scope of the present invention. be able to.

[Reference Example 1]
As Reference Example 1, a battery having the same configuration as that of Battery 1 according to Reference Form 1 was produced.
The positive electrode plate was produced as follows.
LiCoO ₂ particles having an average particle size of 3 μm as a positive electrode active material, acetylene black (AB) as a conductive auxiliary agent, and polyvinylidene fluoride (PVDF) as a binder are LiCoO ₂ / AB / PVDF = 94/3/3. A positive electrode paste was prepared by mixing the mixture so as to be (part by mass) to obtain a positive electrode mixture and dispersing the mixture in N-methyl-2-pyrrolidone (NMP).
Using a doctor blade, the positive electrode paste is 13 μm in thickness so that the mass of the positive electrode mixture excluding NMP is 0.020 g / cm ² per side, and is even on both sides of the positive electrode current collector made of aluminum. After coating, the film was dried at 150 ° C. for 1 hour. And the electrode plate was pressed so that thickness might be set to 130 micrometers at room temperature, and the positive electrode plate in which the mixture layer was formed on both surfaces of the positive electrode collector was obtained.

The negative electrode plate was produced as follows.
Graphite (graphite) as the negative electrode active material and PVDF as the binder were mixed at a mass ratio of 90:10 to form a negative electrode mixture, and an appropriate amount of NMP was added and dispersed therein to obtain a negative electrode paste.
Using a doctor blade, the negative electrode paste is 6 μm thick so that the mass of the negative electrode mixture excluding NMP is 0.0095 g / cm ² per side, and is uniformly applied to both sides of the copper negative electrode current collector. After coating, drying was performed at 150 ° C. for 1 hour. And the electrode plate was pressed so that thickness might be 145 micrometers at room temperature, and the negative electrode plate was obtained.

As the separator, a polyethylene microporous film having a thickness of about 16 μm was used.
The electrode group was produced by sandwiching a separator between the positive electrode plate and the negative electrode plate and winding the separator.
As the non-aqueous electrolyte, a solution in which 1.1 mol / L of LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3: 7 was used.

Then, the negative electrode terminal 4 according to the reference form 1 is crimped to the current collector 7 and fixed to the lid portion 3, and the tabs 71 and 81 of the current collectors 7 and 8 are respectively connected to the negative electrode lead and the positive electrode lead of the electrode group. The electrode group was accommodated in the case 2 while being connected to the lid 3, and the lid 3 was fixed to the opening of the case 2 and welded. And the said nonaqueous electrolyte was inject | poured from the liquid injection hole, the liquid injection hole was sealed, and the battery 1 was produced.
The battery 1 has a length of 50 mm, a width of 34 mm, and a thickness of 4 mm, the leg portion 42 of the negative electrode terminal 4 has an outer diameter of 1 mm and a thickness of 0.15 mm, the current collector 7 has a thickness of 0.2 mm, and the insertion hole 72 has an inner diameter of 1. .05 mm, and the notches 72 a and 72 a have a radius of 0.15 mm.

[Reference Example 2]
Except for using the current collector 11 according to the reference form 2 as a current collector, using the negative electrode terminal 14 according to the reference form 2 as a negative electrode terminal, and crimping the negative electrode terminal 14 to the current collector 11, A battery was produced in the same manner as in Reference Example 1.
The protrusion 11b of the current collector 11 has a width of 0.4 mm, a protrusion length of 0.2 mm, and a thickness of 0.2 mm.

[Reference Example 3]
A battery was fabricated in the same manner as in Reference Example 1 except that the current collector 12 according to Reference Form 3 was used as a current collector and the negative electrode terminal 4 was crimped on the current collector 12.
The inner diameter of the insertion hole 12a of the current collector 12 is 1.05 mm, and the radii of the notches 12b and 12b are 0. 15 mm. The protrusion 12c has an arc length of 1.35 mm, a protrusion length of 0.2 mm, and a thickness of 0.2 mm.

[Reference Example 4]
A battery was fabricated in the same manner as in Reference Example 1 except that the current collector 13 according to Reference Form 4 was used as a current collector and the negative electrode terminal 4 was crimped on the current collector 13.
The length of one side of the insertion hole 13a of the current collector 13 is 1.05 mm.

[Example]
Except for using the current collector 13 according to the embodiment as a current collector, using the negative electrode terminal 15 according to the embodiment as a negative electrode terminal, and caulking the negative electrode terminal 15 to the current collector 13, A battery was produced in the same manner as in Reference Example 1.
The length of one side of the leg portion 15b of the negative electrode terminal 15 is 1 mm.

[Comparative example]
A battery was fabricated in the same manner as in Reference Example 1 except that the current collector 57 shown in FIG. 13 was used as the current collector and the negative electrode terminal 4 was crimped on the current collector 57.

[Battery drop test]
Ten batteries of Examples and Reference Examples 1 to 4 and Comparative Example were produced, and the following drop test was performed.
The drop test was carried out by allowing the battery to drop freely from a height of 1.5 m onto a concrete surface. Dropping the 6 surfaces of the battery downward in order was one cycle, and the internal resistance of the battery after 10 cycles was measured for each battery. The case where there was an increase in resistance of 10 mΩ or more relative to the initial value was rejected, and the case where there was no increase in resistance was determined as acceptable. The results of this drop test are shown in Table 1 below. The numbers in Table 1 represent the number of batteries.

In the case of the comparative example, it can be seen that the contact state of 60% of the batteries deteriorated and the connection resistance increased, whereas the examples and reference examples 1 to 4 all passed.
As described above, the joint portion between the current collector and the negative electrode terminal of this embodiment has a rotation suppression structure that suppresses rotation of the negative electrode terminal, so that the contact state between the current collector and the negative electrode terminal is stabilized and the battery falls. Thus, it was confirmed that the contact resistance was prevented from increasing due to the contact failure when the impact was applied.

In the embodiment and the reference forms 1 to 4, the case where the battery 1 is a lithium ion secondary battery in which the negative electrode terminal 4 penetrates the lid 3 is described, but the present invention is not limited to this. Absent. For the battery in which the positive electrode terminal passes through the lid, the rotation suppression structure according to the present invention may be applied to the joint portion between the positive electrode terminal and the current collector. In this case, the case is made of iron, the current collector is made of aluminum, and the positive electrode terminal is made of aluminum.
And in the said embodiment and the reference forms 1 thru | or 4, although demonstrated about the case where the case 2 makes a substantially rectangular parallelepiped shape, it is not limited to this, The rotation suppression structure of this invention is the case 2 The cylindrical lithium ion secondary battery can be applied to a rectangular lithium ion secondary battery in which the opening surface has an oval shape, that is, the narrow side surface has a curved surface. It is also possible to apply to.
Furthermore, the rotation suppression structure of the present invention can be applied to other secondary batteries such as a nickel / hydrogen secondary battery and a nickel / cadmium secondary battery, and can also be applied to a primary battery.

DESCRIPTION OF SYMBOLS 1 Battery 2 Case 3 Cover part 31 Rupture valve 32 Recessed part 33 Protrusion part 4, 14, 15 Negative electrode terminal 41, 14a, 15a Head part 42, 14b, 15b Leg part 43, 14c Clamping part 5 Gasket 6 Insulator 7, 8, 11, 12, 13 Current collector 71, 81 Tab 72, 11a, 12a, 13a Insertion hole 72a, 12b Notch 11b, 12c Projection

Claims (1)

A terminal penetrating the lid of the battery case;
A current collector provided with an insertion hole, disposed on the inner surface side of the lid, and joined to the terminal by inserting the terminal through the insertion hole;
In a battery comprising an insulator interposed between the terminal and the current collector and the lid,
The junction between the current collector and the terminal is:
The insertion hole has a polygonal shape,
A battery in which a portion of the terminal through which the insertion hole is inserted has a polygonal shape that is the same shape as the insertion hole in a plan view.