JP2001210384A - Nonaqueous electrolytic solution secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution secondary battery in which lead wires to be damaged can be prevented. SOLUTION: An electrode element 2 is composed of a wound positive electrode, a negative electrode and a laminated film of separator. On one side of canned sheath 1, a cap body 7, a PTC element 3 and a relief valve 6 are caulked via a gasket 8, and sealed. At the central part of relief valve 6, a protruding portion 6a is formed. This protruding portion 6a is welded to a sub-disk 4 through a center hole of disk 11. An insulation plate 15 is arranged on the opening side of canned sheath 1. As for a center hole 15a, the shape is almost circular except a convex part 15b. A convex part 15b is installed in the center hole 15a of insulation plate. This convex part 15b prevents appearing to the outside than insulation plate 15 when a center pin 17 has moved. This convex part 15b is integrally made with the insulation plate 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, portable information devices such as laptop computers and word processors, camera-integrated video tape recorders, AV devices such as liquid crystal televisions, and mobile communication devices such as mobile phones have been remarkably developed. There is a demand for a small, lightweight, high energy density secondary battery for the battery used. Until now, aqueous secondary batteries such as lead batteries, nickel cadmium batteries, nickel hydride batteries and the like have been used, but they are not sufficient with respect to demands for weight reduction, high energy density, and the like.

[0003] Recently, non-aqueous electrolyte secondary batteries have attracted great interest and expectations as clean batteries having a high energy density. Here, a conventional non-aqueous electrolyte secondary battery will be described. FIG. 3 is a sectional view showing a conventional non-aqueous electrolyte secondary battery. In this non-aqueous electrolyte secondary battery,
An electrode element 2 is housed in a cylindrical outer can 1, a non-aqueous electrolyte is injected into the outer can 1, and the non-aqueous electrolyte is impregnated in the electrode element 2.

In the electrode element 2, a film-like positive electrode and a film-like negative electrode are laminated via a film-like separator, and the laminated film is spirally wound around, for example, a cylindrical core. ing.

[0005] One end of each of the positive electrode lead 9 and the negative electrode lead 10 is welded from the opposite end of each current collector foil to each of the positive electrode electrode and the negative electrode. The negative electrode lead 10 is led out of the element 2 and is led out from the outer peripheral side of the electrode element 2.

The center pin 17 is housed in the space of the electrode element 2. The insulating plates 15 and 16 are arranged so as to sandwich the electrode element 2. The insulating plate 15
The free ends of the positive electrode lead 9 and the negative electrode lead 10 of the electrode element 2 are led out of the electrode elements 16 and 16. Then, the free end of the negative electrode lead 10 is welded to the bottom surface of the outer can 1.

Here, the insulating plate 15 will be described in detail with reference to FIG. FIG. 4 is a sectional view showing a conventional nonaqueous electrolyte secondary battery and a plan view showing an insulating plate. The outer shape of the insulating plate 15 is substantially circular. In the insulating plate 15, a center hole 15a and an outer peripheral hole 15c are provided.

The center hole 15a has a substantially circular shape. This circle is centered on the symmetrical point of the insulating plate 15. One of the functions of the center hole 15a is that the positive electrode lead 9 led out from the center side of the electrode element 2 is connected to the center hole 1a.
5a. Outer hole 15
c are provided on the outer peripheral side of the insulating plate 15. Its shape is almost circular.

As shown in FIG. 3, a lid 7, a PTC element 3, and a safety valve 6 are caulked through a gasket 8 and sealed at one end of the outer can 1. Thereby, the lid 7, the PTC element 3, and the safety valve 6 are electrically connected.

The safety valve 6 has a projection 6a formed at the center thereof to project toward the electrode element 2 side. The projection 6a is welded to the sub-disk 4 through the center hole of the disk 11. Thus, the protrusion 6a is electrically connected to the sub-disk 4.

[0011]

However, the above-mentioned conventional non-aqueous electrolyte secondary battery has a problem as shown in FIG. FIG. 5 is a cross-sectional view showing a conventional non-aqueous electrolyte secondary battery in which a positive electrode lead is broken by movement of a center pin. As can be seen from FIG. 5, vibration / shock is applied to the battery, and the center pin 17 may move past the center hole 15 a of the insulating plate 15. in this case,
When the center pin 17 repeatedly presses the positive electrode lead 9, stress is concentrated on the bent portion, and there is a problem that the positive electrode lead 9 is damaged or broken.

In order to solve this problem, the following non-aqueous electrolyte secondary battery has been proposed. FIG. 6 is a sectional view showing another conventional nonaqueous electrolyte secondary battery and a plan view showing an insulating plate. That is, as shown in FIG. 6B, the center hole 15d of the insulating
7 is prevented from jumping out. However, in this case, the positive electrode lead 9 cannot be led out from the center hole 15d. Therefore, as shown in FIG. 6A, it is necessary to lead the positive electrode lead 9 from the outer peripheral hole 15e. Therefore, it is necessary to lead the positive electrode lead 9 from a substantially central portion of the electrode element 2. However, in order for the positive electrode lead 9 to be led out from the substantially central portion of the electrode element 2, the coating process on the positive electrode current collector becomes complicated, and the insulation of the positive electrode current collector portion where the positive electrode lead 9 is welded is ensured. There is a problem that an additional step is required.

In order to avoid this problem, it is conceivable that the positive electrode lead 9 as shown in FIG. FIG. 7 is a cross-sectional view showing a state in which a positive electrode lead is bent by an insulating plate in another conventional nonaqueous electrolyte secondary battery. As can be seen from FIG. 7, a portion where the positive electrode lead 9 protrudes from the electrode element 2 is pressed by the insulating plate 15. Therefore, the positive electrode lead 9 is bent, and a bent portion 9b is generated. Then, there is a problem that the bent portion 9b is damaged or broken.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a non-aqueous electrolyte secondary battery that can prevent leads from being damaged.

[0015]

According to the present invention, there is provided a nonaqueous electrolyte secondary battery comprising: an outer can; an electrode element housed in the outer can, wherein a positive electrode lead is led out from the center of the outer can; A non-aqueous electrolyte secondary battery in which the positive electrode lead is led out through the center hole, the insulating plate being provided with a center hole. It has a convex portion in the hole.

Further, the non-aqueous electrolyte secondary battery of the present invention is the above-described non-aqueous electrolyte secondary battery in which the projections are integral with the insulating plate.

According to the non-aqueous electrolyte secondary battery of the present invention, since the insulating plate has a convex portion in the center hole thereof, the non-aqueous electrolyte secondary battery is subjected to a drop or vibrational impact, and the center pin is displaced. Even when the center pin moves to the safety valve side, the insulating plate suppresses the movement of the center pin to the safety valve side.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention relating to a non-aqueous electrolyte secondary battery will be described. First, the configuration of the nonaqueous electrolyte secondary battery according to the present embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating the nonaqueous electrolyte secondary battery according to the present embodiment. In this embodiment,
The present invention is applied to a non-aqueous electrolyte lithium secondary battery comprising a material capable of doping and undoping lithium in a positive electrode and / or a negative electrode and including a non-aqueous electrolyte. It is not limited to the embodiment and the example of FIG.

In this embodiment, nickel (N
i) An electrode element 2 is accommodated in a plated iron-made cylindrical outer can 1, and a non-aqueous electrolyte (not shown) is injected into the outer can 1. The element 2 is impregnated. The outer can 1 is not limited to the cylindrical type as described above. In addition, batteries having other cylindrical shapes including a square shape and an elliptical shape may be used.

In the electrode element 2, a film-shaped positive electrode and a film-shaped negative electrode are laminated via a film-shaped separator, and the laminated film is spirally wound around, for example, a cylindrical core. It becomes.

The positive electrode and the negative electrode of the electrode element 2 are
For example, aluminum (Al) foil and copper (C
u) A positive electrode active material and a negative electrode active material are applied to both sides of a strip-shaped current collector foil made of a foil.

One end of a positive electrode lead 9 made of Al and one end of a negative electrode lead 10 made of Ni are welded from opposite ends of the respective collector foils of each of the positive electrode and the negative electrode to the center of the electrode element 2. , The positive electrode lead 9 is led out of the electrode element 2, and the negative electrode lead 10 is led out from the outer peripheral side of the electrode element 2. The electrode element 2 is inserted into the outer can 1 with the lead-out side of the negative electrode lead 10 on the bottom side of the outer can 1.

In the above-described electrode element 2, the positive electrode active material of the positive electrode is, for example, a material capable of undoping and re-doping Li, for example, an active material L made of a lithium transition metal composite oxide.
i _x MO ₂ (M is, Co, Ni, one or more transition metals of Mn, 0.4 ≦ x ≦ 1.1) composite oxide represented by, among others _{LiCoO 2, LiNiO 2, LiMn 2} O 4 , etc. Is preferred. Such lithium transition metal oxides include, for example, carbonates, nitrates, oxides of Li, Co, Ni, and Mn.
It is obtained by mixing hydroxides or the like as starting materials in an amount corresponding to the composition and firing the mixture in a temperature range of 600 ° C to 1000 ° C.

The negative electrode active material of the negative electrode is, for example, L
a substance that can be doped or undoped with i, for example, a low-crystalline carbon material obtained by firing at a relatively low temperature of 2000 ° C. or less, artificial graphite or natural graphite obtained by treating a material that is easily crystallized at a high temperature of about 3000 ° C. Is used. For example, pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound fired products (furan resin or the like fired at an appropriate temperature and carbonized), carbon fiber, activated carbon, and the like can be used. is there.

The low-crystalline carbon material is preferably a material obtained by calcining furan resin or petroleum pitch at a temperature of less than 1500 ° C. and having a (002) plane spacing of 3.70 angstroms by wide-angle X-ray diffraction. As described above, the true density is 1.7.
A carbonaceous material that is less than 0 g / cm ³ and does not have an exothermic peak at 700 ° C. or more in differential thermal analysis in an air stream is used. As the graphite powder, a carbonaceous material having a (002) plane spacing of less than 3.42 angstroms by a wide-angle X-ray diffraction method is preferably used. These carbonaceous materials have a large amount of Li doping and undoping and are excellent in charge / discharge cycle life performance, and the anode material is most suitable for the equipment to be used in combination with the cathode material Combinations can be selected.

The separator can be composed of, for example, a microporous film of polyethylene, polypropylene or Teflon.

The non-aqueous electrolyte comprises an organic solvent and an electrolyte dissolved therein. Alternatively, a so-called polymer electrolyte obtained by mixing a non-aqueous electrolyte with a polymer compound, or a polymer electrolyte obtained by mixing or binding an electrolyte to a polymer compound can be used. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate, dimethyl carbonate, chain carbonates such as diethyl carbonate, γ-butyrolactone, γ
-One or more of cyclic esters such as parolelactone, chain esters such as ethyl acetate and methyl propionate, and ethers such as tetrahydrofuran and 1,2-dimethoxyethane can be used. As the electrolyte, for example, a lithium salt that dissolves in the solvent used and exhibits ionic conductivity, such as Li
PF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ S
O ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO
₂ ) One or more types such as ₃ can be used.

The center pin 17 has a substantially cylindrical shape, and has tapered ends. Here, the diameter decreases as going to both ends. The center pin 17 is made of metal. The center pin 17 is shown in FIG.
As shown in (2), it is housed in the space of the electrode element 2. The function of the center pin 17 is to prevent the space of the electrode element from being crushed when the non-aqueous electrolyte secondary battery is crushed, and to prevent the passage of gas generated inside the battery from being blocked. is there.

The insulating plates 15 and 16 hold the electrode element 2 therebetween, and open the outer can 1 (hereinafter referred to as “upper side”).
And on the bottom side of the outer can 1 (hereinafter, referred to as “lower side”). As a material of the insulating plates 15 and 16,
Plastics such as polypropylene (PP) and glass cloth impregnated with phenolic resin and laminated
Commonly used materials can be used.

The free ends of the positive electrode lead 9 and the negative electrode lead 10 of the electrode element 2 are led out of the insulating plates 15 and 16. The free end of the negative electrode lead 10 is welded to, for example, the bottom surface of the outer can 1 serving as an electrode terminal lead-out portion.

Here, the insulating plate 15 will be described in detail with reference to FIG. 1B. FIG. 1B is a plan view showing an insulating plate used for the nonaqueous electrolyte secondary battery according to the present embodiment. The outer shape of the insulating plate 15 is substantially circular, and a central hole 15a, a convex portion 15b, and an outer peripheral hole 15c are provided therein.

The center hole 15a has a shape corresponding to the convex portion 15b.
It is almost circular except for. This circle is centered on the center point of the insulating plate. The function of the center hole 15a is to allow the cathode lead 9 led out from the center side of the electrode element 2 to be led out through the center hole 15a, and to weld the anode lead 10 to the bottom of the outer can 1 with a welding rod. And passing gas generated inside the battery.

A projection 15b is provided in the center hole 15a of the insulating plate. The function of the projection 15b is to prevent the center pin 17 from going outside the insulating plate 15 when the center pin 17 moves. The shape of the projection 15b is a substantially rectangular shape with rounded corners, and the thickness of the projection 15b is the same as other portions of the insulating plate. This projection 15b is
It is integral with the insulating plate 15.

The protrusion 15b is not limited to the one shown in FIG. 1B. The number of the protrusions 15b may be plural, and the size of the protrusions 15b shown in FIG.
May be larger or smaller than. Further, the shape of the convex portion 15b may be a shape obtained by cutting a part of a circle. In short, any shape can be adopted as long as the positive electrode lead 9 can be led out and the movement of the center pin 17 can be prevented.

The outer peripheral hole 15c is formed on the outer peripheral side of the insulating plate 15.
Are provided. Its shape is almost circular. The function of the outer peripheral hole 15c is to serve as a passage for the electrolytic solution when impregnating the electrode element 2 with the electrolytic solution, and to pass the gas when the gas is generated inside the battery. In addition,
The insulating plate 15 may be disposed not only above the electrode element 2 but also below the electrode element 2.

As shown in FIG. 2, a lid 7, a PTC element 3, and a safety valve 6 are crimped through a gasket 8 and sealed at one end of the outer can 1. That is, for example, a lid 7 serving as a positive electrode side lead-out portion made of stainless steel, Ni, or Fe, and a ring-shaped P having positive temperature characteristics, for example.
The TC element 3 and a safety valve 6 made of, for example, Al disposed inside the TC element 3 are sandwiched by a gasket 8 and caulked to the open end of the outer can 1 to be sealed. As a result, the lid 7, the PTC element 3, and the safety valve 6 are electrically connected.

The safety valve 6 has a projection 6a projecting toward the electrode element 2 at the center thereof. The protrusion 6a is provided in the center hole 11 of the disk 11 (described later).
c, it is welded to the sub-disk 4 (described later). Thus, the protrusion 6a is electrically connected to the sub-disk 4.

The disk 11 is fixed inside the safety valve 6 via a disk holder 12. This disk 1
1 is made of a metal plate such as Al. The disk holder 12 has a function of electrically insulating the safety valve 6 and the disk 11 from each other.

The sub-disk 4 is a thin disk having a thin shape, and is made of, for example, a metal such as Al. This subdisk 4 is located at the center of the disk 11 and the disk 1
1 is welded to the electrode element 2 side. The free end of the positive electrode lead 9 is welded to the surface of the sub-disk 4 on the electrode element 2 side. Thus, the sub-disk 4 and the positive electrode lead 9 are electrically connected. As a result, the protrusion 6a of the safety valve 6 is electrically connected to the positive electrode lead 9.

Next, the operation of the center pin in the non-aqueous electrolyte secondary battery according to the present embodiment will be described with reference to FIG. 1A. FIG. 1A is a cross-sectional view showing movement of a center pin and the function of an insulating plate in the nonaqueous electrolyte secondary battery according to the present embodiment.

The center pin 17 is housed in the space of the electrode element 2. A frictional force is generated between the outer peripheral surface of the center pin 17 and the inner peripheral surface of the electrode element 2. Therefore, when the non-aqueous electrolyte secondary battery is stationary or when it is moving but its acceleration is small, the center pin 1
The center pin 17 does not move because a frictional force acts on 7.

However, when the acceleration increases due to the non-aqueous electrolyte secondary battery falling or being subjected to vibration, the force acting on the center pin 17 exceeds the frictional force,
The center pin 17 moves. When the center pin 17 moves to the upper side of the electrode element 2, when the upper end of the center pin 17 moves to the inner surface of the insulating plate 15, the center pin 17 hits the inner surface of the convex portion 15b. Therefore, the center pin 17 cannot move outside the inner surface of the insulating plate 15.

As described above, the insulating plate 15 has its center hole 15
c, the non-aqueous electrolyte secondary battery is subjected to a drop or vibrational impact, and even if the center pin 17 moves to the safety valve 6 side, the insulating plate 15 moves the center pin to the safety valve 6 side. 17 movement is suppressed.

Next, a test was conducted to confirm the effect of the insulating plate used for the nonaqueous electrolyte secondary battery according to the present embodiment, and the results will be described. In this test, a non-aqueous electrolyte secondary battery according to the present embodiment (hereinafter, referred to as “battery of the present embodiment”) and a conventionally used non-aqueous solution for comparison with the battery of the present embodiment. An electrolyte secondary battery (hereinafter, referred to as “conventional battery”) was used. As the battery of the present embodiment, a battery using the insulating plate 15 shown in FIG. 1B was used. A conventional battery using the insulating plate 15 shown in FIG. 4B was used. Except for these insulating plates, both batteries have the same configuration.

In the test, the battery was placed 10
Performed by dropping from a height of cm. And
The number of times until the positive electrode lead was broken was counted. Further, when the positive electrode lead did not break even after the number of drops reached 5,000, it was determined that sufficient effect was recognized, and no further drop test was performed. Note that five battery samples were prepared for both the battery of the present embodiment and the conventional battery.

The results of the drop test of the battery of this embodiment and the conventional battery are as shown in Tables 1 and 2. As can be seen from Table 2, in the conventional battery, sample 1
In Nos. To 5, it was recognized that the positive electrode lead was broken by falling 2500 to 4000 times. On the other hand, in the battery of the present embodiment, in all of the samples 1 to 5, the positive electrode lead did not break until the number of drops was 5000. As a result of observing the battery of the present embodiment after the test, the movement of the center pin 17 was prevented by the convex portion of the insulating plate. In addition, no damage was observed on the projections, and thus no damage or breakage of the positive electrode lead was observed.

[0047]

[Table 1]

[Table 2]

As described above, the convex portion is provided in the center hole of the insulating plate that insulates between the electrode element and the safety valve, and even when the center pin is moved to the safety valve side due to the drop or the impact of vibration, the insulating plate is still in place. Since the movement of the center pin to the safety valve side is suppressed, the lead can be prevented from being damaged or broken. That is, the electrode element and the lead or the center pin can be fixed by the convex portion in the center hole, and the lead and the electrode can be prevented from being broken due to impact stress due to vibration and shock and bending.

The present invention is not limited to the above embodiment, but can be applied to other batteries having a center pin and an insulating plate. In addition, the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0050]

The present invention has the following effects. Since the insulating plate has a protrusion in its center hole,
Even when the non-aqueous electrolyte secondary battery is dropped or vibrated, and the center pin moves to the safety valve side, it is possible to prevent the lead from being damaged.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the movement of a center pin and the function of an insulating plate, and a plan view showing an insulating plate in a nonaqueous electrolyte secondary battery according to the present embodiment.

FIG. 2 is a cross-sectional view showing a non-aqueous electrolyte secondary battery according to the present embodiment.

FIG. 3 is a cross-sectional view showing a conventional non-aqueous electrolyte secondary battery.

FIG. 4 is a cross-sectional view showing a conventional nonaqueous electrolyte secondary battery and a plan view showing an insulating plate.

FIG. 5 is a cross-sectional view showing a state in which a positive electrode lead is broken by movement of a center pin in a conventional nonaqueous electrolyte secondary battery.

FIG. 6 is a cross-sectional view showing another conventional non-aqueous electrolyte secondary battery and a plan view showing an insulating plate.

FIG. 7 is a cross-sectional view showing a state in which a positive electrode lead is bent by an insulating plate in another conventional nonaqueous electrolyte secondary battery.

[Explanation of symbols]

1 ‥‥ Outer can, 2 ‥‥ Electrode element, 3 ‥‥ PTC element, 4
{Sub disk, 6} Safety valve, 6a Projection, 7
{Cover, 8} Gasket, 9} Positive electrode lead, 9a
{Break, 9b} Bend, 10} Negative electrode lead, 11} Disk, 12} Disk holder, 15
{Insulating plate, 15a} center hole, 15b} convex, 15
c ‥‥ peripheral hole, 15d ‥‥ center hole, 15e ‥‥ peripheral hole,
16mm insulation board, 17mm center pin

Claims (2)

[Claims] 1. An outer can, an electrode element housed in the outer can, wherein a positive electrode lead is led out from a center side of the outer can, and an insulating plate arranged on the electrode element, wherein a center hole is provided. Provided, wherein the positive electrode lead is a non-aqueous electrolyte secondary battery led out through the center hole, wherein the insulating plate has a protrusion in the center hole. Non-aqueous electrolyte secondary battery. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the projection is integral with the insulating plate.