JP3349601B2 - Explosion-proof sealed battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof sealed battery, and more particularly, to an explosion-proof sealed battery capable of preventing a fire or explosion by interrupting a current even when overcharged or short-circuited.

[0002]

2. Description of the Related Art Recently, sealed batteries using an organic solvent-based electrolyte such as lithium batteries and lithium secondary batteries have been widely used as power supplies for portable devices such as watches and cameras.

However, in a sealed battery using such an organic solvent-based electrolyte, a power generation element inside the battery undergoes a chemical change, the pressure inside the battery increases, and the battery sometimes bursts under high pressure.

[0004] For example, when a lithium secondary battery is overcharged or short-circuited and a large current flows, the electrolytic solution is decomposed, and as a result, gas is generated inside the battery. The pressure inside the battery increases, and eventually the battery may burst under high pressure.

[0005] Further, even in a lithium primary battery, the pressure inside the battery rises due to forced overcharge or overdischarge, or forced discharge from another battery, and the like, and there is a possibility that the battery may eventually ignite. .

Therefore, conventionally, a battery is provided with a so-called explosion-proof function of discharging gas generated inside the battery to the outside of the battery to prevent the battery from bursting under high pressure.

For example, as shown in FIG. 8, a pressure inlet 1b through which a gas can pass is provided in a lead member mounting member 1 also serving as a sealing plate, and a gas discharge hole 2a and a cutting blade 2b are provided in a terminal plate 2.
And a flexible thin plate 16 is disposed between the lead member mounting member 1 and the terminal plate 2. When gas is generated inside the battery and the internal pressure of the battery rises, the flexible thin plate 16 is It bulges toward the terminal plate 2 and is broken by contacting the cutting blade 2b, thereby discharging gas inside the battery from the gas discharge hole 2a of the terminal plate 2 to the outside of the battery, thereby preventing the battery from bursting under high pressure. The battery is provided with a so-called explosion-proof function (for example, Japanese Utility Model Laid-Open No. 2-71966).

As shown in FIG. 9, a thin portion 6a is provided in the shape of a cross at the bottom of the battery case 6. When gas is generated inside the battery and the internal pressure of the battery rises, the thin portion 6a is removed. Ruptures the gas inside the battery and releases it outside the battery.
It has also been practiced to prevent the battery from bursting under high pressure (for example, JP-A-63-285859).

[0009]

However, although the conventional explosion-proof sealed battery as described above can prevent the explosion under a high pressure due to an increase in the internal pressure of the battery, for example, when the battery is overcharged, the charging current is reduced. As a result, the electrolytic solution and active material inside the battery continue to decompose, thereby increasing the temperature of the battery and the internal pressure of the battery, and eventually causing ignition or rupture.

Accordingly, the present invention solves the above-mentioned problems of the conventional explosion-proof sealed battery, and can prevent the battery from being ignited or ruptured even when overcharged or short-circuited. It is an object of the present invention to provide an explosion-proof sealed battery with high performance.

[0011]

The construction of the present invention for solving the above-mentioned problems will be described with reference to FIGS. 1 to 4 corresponding to the embodiment.
A thin portion 1a is provided on the inner side from both end surfaces in the thickness direction of the lead body mounting member 1, and the protrusion 3a of the explosion-proof valve 3 is deformed in the thin portion 1a in the internal pressure direction as the internal pressure of the battery rises.
Is welded, and the lead body 8 is attached to the lead body attaching member 1, so that when the internal pressure of the battery rises and reaches a predetermined pressure, the lead body attaching member 1 is located on the inner side from both end faces in the thickness direction. The thin portion 1a provided is the explosion-proof valve 3
The above-mentioned object is achieved by breaking by the shearing force generated due to the deformation in the direction of the internal pressure, or by peeling off the welded portion 5 between the thin portion 1a and the protruding portion 3a of the explosion-proof valve 3 to cut off the current. It has been achieved.

That is, in a normal state, as shown in FIG.
The explosion-proof valve 3 has a thin portion 1a and a protruding portion 3 of the explosion-proof valve 3.
a is integrated by welding, the electrical connection from the positive electrode 9 to the terminal plate 2 is ensured by the lead body 8, the lead body mounting member 1, the explosion-proof valve 3, and their welded parts 5. However, when the electrolyte or the active material is decomposed due to an abnormal reaction due to overcharge or short circuit and gas is generated inside the battery, explosion proof is performed by the gas generated inside the battery as shown in FIG. When the valve 3 is pressed and deformed in the direction of the internal pressure (the direction in which the internal pressure is diffused), the thin portion 1a of the lead body mounting member 1 is deformed.
Then, the thin portion 1a is broken by generating a shearing force, or the welded portion 5 between the thin portion 1a of the lead body attaching member 1 and the protruding portion 3a of the explosion-proof valve 3 is peeled off as shown in FIG.

As a result, the electrical connection from the positive electrode 9 to the terminal plate 2 is lost in the initial stage of overcharging or short circuit, the current is interrupted and the reaction is stopped, and the temperature of the battery caused by the charging current or the short circuit current is reduced. The rise and internal pressure rise are suppressed, and the ignition and rupture of the battery are prevented.

In the present invention, the reason why the thin portion 1a is provided on the inner side from both end surfaces in the thickness direction of the lead member mounting member 1 is that the thin portion 1a is provided on one of the end surfaces. As compared with the case, the tensile stress acting on the thin-walled portion 1a can be suppressed, and the shearing force required to break the thin-walled portion 1a can be applied more, so that the reliability of interrupting the current is improved. Because.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to only those illustrated in the embodiments.

FIG. 1 is a longitudinal sectional view showing an embodiment of an explosion-proof sealed battery according to the present invention. 2A and 2B show a lead member mounting member used in the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 2A is a plan view and FIG. 2B is a longitudinal sectional view. is there. 3 shows an explosion-proof valve used in the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 3 (a) is a plan view thereof, and FIG. 3 (b) is a longitudinal sectional view thereof. FIG. 4 is an enlarged cross-sectional view around the thin portion of the lead member mounting member. FIG. 5 is a longitudinal sectional view showing a state in which the explosion-proof valve of the explosion-proof sealed battery shown in FIG. 1 is deformed in the direction of the internal pressure by receiving the internal pressure of the battery, and the thin portion provided on the lead member attaching member is broken. FIG. 6 shows a state in which the explosion-proof valve of the explosion-proof sealed battery shown in FIG. 1 is deformed in the direction of the internal pressure due to the internal pressure of the battery, and the welded portion between the thin portion of the lead member mounting member and the projection of the explosion-proof valve is peeled off. FIG.

First, the components of the battery will be schematically described with reference to FIG. 1. 1 is a lead member attaching member, 2 is a terminal plate, 3 is an explosion-proof valve, 4 is an insulating packing, 5 is a welded portion,
6 is a battery case, 7 is an annular gasket, 8 is a lead body on the positive electrode side, 9 is a positive electrode, 10 is a negative electrode, 11 is a separator, 1
2 is an electrolyte, 13 is an insulator, 14 is an insulator, and 15 is a lead on the negative electrode side.

The lead mounting member 1 has a function as a sealing plate. The lead mounting member 1 is made of aluminum, titanium, nickel, stainless steel or the like and has a disk shape. As shown in the figure, thin portions 1a are provided in the center part on the inner side from both end surfaces in the thickness direction, and pressure introduction ports 1b for applying an internal pressure to the explosion-proof valve 3 around the thin portions 1a are provided at four places. A hole is provided. The projection 3a of the explosion-proof valve 3 is welded to the upper surface of the thin portion 1a to form a welded portion 5.

The thin section 1a provided on the lead member mounting member 1 and the protruding section 3a of the explosion-proof valve 3 are shown only on the cut surface for easy understanding in the drawings. The contour line behind the surface is not shown. Also,
The welded portion 5 between the thin portion 1a of the lead body mounting member 1 and the protruding portion 3a of the explosion-proof valve 3 is also shown in an exaggerated state in order to facilitate understanding in the drawings.

The terminal plate 2 is made of a metal material in which iron is plated with nickel, stainless steel or a metal material in which stainless steel is plated with nickel, and has a hat-like shape with a peripheral edge formed in a flange shape. The terminal plate 2 is provided with a gas discharge hole 2a.

The explosion-proof valve 3 is made of a metal material such as aluminum, titanium, nickel, and stainless steel, and has a disk shape. The center of the explosion-proof valve 3 is located on the power generation element side (the lower side in FIG. 1). Is provided, and the lower surface of the protrusion 3a is welded to the upper surface of the thin portion 1a of the lead body mounting member 1 as described above, thereby forming a welded portion 5.

The insulating packing 4 is made of a synthetic resin having an electrolytic solution resistance such as polypropylene, and has an annular shape. The gap between the two is sealed so that the electrolyte does not leak.

The battery case 6 is formed of a metal material obtained by plating nickel on iron or a metal material such as stainless steel, and the annular gasket 7 is formed of a synthetic resin having electrolytic resistance such as polypropylene. . The lead body 8 is made of a metal material such as aluminum, titanium, and stainless steel.
And are connected.

The positive electrode 9 is made of, for example, MnO ₂ , Ti
S ₂ , MoS ₂ , V ₂ O ₅ , Li _x MnO _y , Li _x N
A positive electrode mixture prepared by mixing iO ₂ , Li _x CoO _2, etc. as an active material, adding a conductive aid such as carbon black and a binder such as polytetrafluoroethylene, etc. In the forming, a stainless steel mesh or the like is used as a core material having a current collecting function. However, in FIG. 1, in order to avoid complication, a core material such as a stainless steel mesh is used. Not shown.

The negative electrode 10 is made of, for example, metallic lithium, a lithium alloy, carbon doped with lithium and undoped, and the like. Although it is used as a support having a current collecting function, in FIG. 1, a support such as a stainless steel net is not shown in order to avoid complication.

The separator 11 is made of a synthetic fiber non-woven fabric such as a polypropylene non-woven fabric or a polyethylene non-woven fabric. The positive electrode 9 and the negative electrode 10 are overlapped via the separator 11 and spirally wound to form a spiral electrode body as a battery case. 6.

The electrolyte solution 12 is, for example, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, diethyl ether LiClO ₄ , LiPF ₆ , LiSbF ₆ , LiA
_{S F 6, LiBF 4, Li} (C 6 H 5) 4, LiCF 3
SO ₃ , LiC ₄ F ₉ SO ₃ , (CF ₃ SO ₂ ) ₂ NL
i, which is formed by dissolving an electrolyte such as (CF ₃ SO ₂ ) ₃ CLi, and is injected into the battery case 6.

An insulator 13 made of a polytetrafluoroethylene sheet or the like is provided at the bottom of the battery case 6. A spiral electrode body comprising the positive electrode 9, the negative electrode 10 and the separator 11, an electrolytic solution 12, a spiral electrode The insulator 14 and the like at the upper part of the body are accommodated in the battery case 6. After these are accommodated, an annular groove whose bottom is protruded inward is formed in the vicinity of the open end of the battery case 6.

Then, the lead gasket 1, the insulating packing 4, and the annular gasket 7 into which the explosion-proof valve 3 is inserted are inserted into the opening of the battery case 6, and the terminal plate 2 is further inserted from above. The opening of the battery case 6 is sealed by tightening the portion ahead of the groove 6 inward.

In assembling the battery as described above, the negative electrode 10 and the battery case 6 are connected in advance with a lead 15 made of a metal such as nickel, copper, or stainless steel.
It is preferable that the lead member 1 is connected to the lead member 1 with a lead member 8 made of metal such as aluminum, titanium, or stainless steel as described above.

In the battery assembled as described above, the thin portion 1a of the lead member attaching member 1 and the projection 3a of the explosion-proof valve 3 come into contact with each other at the welded portion 5, and the peripheral portion of the explosion-proof valve 3 and the terminal plate 2, the positive electrode 9 and the lead member mounting member 1 are connected by the lead member 8 on the positive electrode side, so that the positive electrode 9 and the terminal plate 2 are connected to the lead member 8, the lead member mounting member 1, The explosion-proof valves 3 and their welded parts 5 provide an electrical connection and function normally as an electrical circuit.

When an abnormal situation occurs in the battery and gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises, as shown in FIG. In the direction (upward direction in FIG. 5), the thin portion 1a integrated at the welded portion 5 is subjected to shearing force, and the thin portion 1a is broken, or FIG.
As shown in FIG. 5, the welded portion 5 between the projection 3a of the explosion-proof valve 3 and the thin portion 1a of the lead body mounting member 1 is peeled off, whereby the electrical connection between the positive electrode 9 and the terminal plate 2 is lost,
The current is interrupted.

As a result, the battery reaction does not proceed, so that even when overcharging or short-circuiting, the rise in temperature or internal pressure of the battery due to the charging current or short-circuit current does not progress further, preventing the battery from firing or rupture. Will be done.

The explosion-proof valve 3 is provided with a thin portion 3b. For example, when charging proceeds extremely and power generation elements such as an electrolyte and an active material are decomposed and a large amount of gas is generated. After the explosion-proof valve 3 is deformed and the welded portion 5 between the projection 3a of the explosion-proof valve 3 and the thin portion 1a of the lead body mounting member 1 is peeled off, the thin portion 3b provided on the explosion-proof valve 3 is cleaved. Gas can be discharged to the outside of the battery from the gas discharge holes 2a of the terminal plate 2 to prevent the battery from bursting.

Next, in the structure shown in FIG. 1, manganese dioxide (MnO ₂ ) was used as a positive electrode active material, lithium was used as a negative electrode, and ethylene carbonate and 1,3 were used as an electrolyte.
LiCF in a mixed solvent having a volume ratio of 1: 2 with dioxolane
An explosion-proof sealed battery using a solution in which ₃ SO ₃ was dissolved at 0.6 mol / l was prepared, and the battery of this example was subjected to an overcharge test under the conditions of a test atmosphere of 20 ° C. and 2.8 A constant current charging. The charging time and battery voltage, charging current,
FIG. 7 shows the relationship between the battery temperatures. In the battery of this embodiment, the lead member attaching member 1 is made of aluminum, the thickness of the main body portion is 0.6 mm, and the thickness of the thin portion 1a is 0.1 mm. The thin portion 1a is provided at a position where the lower surface thereof enters 0.1 mm from the lower surface of the lead body attaching member 1 (in FIG. 4, the distance from the lower surface is represented by t2). It is the same as the thickness (in FIG. 4, the thickness of the thin portion 1a is represented by t1).

As shown in FIG. 7, when the battery of the embodiment enters an overcharged state (at the time when the battery temperature gradient starts rising), the charging current is cut off, and the battery temperature starts to drop. This is because when the battery is overcharged, the explosion-proof valve 3 is deformed in the direction of the internal pressure due to an increase in the internal pressure of the battery, thereby breaking the thin portion 1a or welding the thin portion 1a to the projection 3a of the explosion-proof valve 3. This is because the portion 5 is peeled off, the electrical connection between the positive electrode 9 and the terminal plate 2 is lost, and the charging current is interrupted. The interruption of the charging current prevents the battery from firing or exploding.

On the other hand, a similar test was conducted on a conventional battery having the same explosion-proof function as shown in FIG. 8 with the same constitution of the active material and the electrolytic solution as the battery of the embodiment. Although the battery was prevented from exploding, it ignited because the charging current continued to flow.

Further, as shown in FIG. 10, the thin portion 1a is provided so that the lower surface thereof is flush with the lower surface of the lead mounting member 1, and as shown in FIG.
Are provided such that the upper surface thereof is flush with the upper surface of the lead member mounting member 1, and the same batteries as those of the example are manufactured using the lead member mounting member 1, and the batteries and those of the example are manufactured. Regarding batteries, each battery is 100
Each of the batteries was subjected to an overcharge test under the same conditions as described above. As a result, as for the batteries of the examples, the explosion-proof function of each of the 100 batteries subjected to the test was normally operated, but as shown in FIG. In the case where the thin portion 1a is provided on the lower surface side of the lead body attaching member 1, 55 of the 100 batteries used in the test are provided.
In the case where the explosion-proof function only operates normally and the thin portion 1a is provided on the upper surface side of the lead body attaching member 1 as shown in FIG. Only the explosion-proof function worked properly.

In the above embodiment, the thin portion 1a is provided at a position separated from the lower surface of the lead body attaching member 1 by the same length as the thickness of the thin portion 1a (see t2 in FIG. 4). The thin portion 1a may be provided at any position as long as it is on the inner side from both end surfaces in the thickness direction of the lead member attaching member 1. In the embodiment, the side surface shape 1c of the lead member attaching member 1 around the thin portion 1a. Was made straight,
The invention is not limited to this. For example, the explosion-proof valve 3 may be formed in an inverted C-shape and the lead body 8 may be formed in a C-shape.

[0040]

As described above, according to the present invention, the thin portion 1a is provided on the lead member attaching member 1 inside the both ends in the thickness direction of the lead member attaching member 1, and the battery internal pressure is applied to the thin portion 1a. The projection 3a of the explosion-proof valve 3, which is deformed in the direction of the internal pressure as the pressure rises, is welded. In a normal state, the electrical connection between the explosion-proof valve 3 and the lead member mounting member 1 is secured by the above welded portion 5 to form an electric circuit. When the internal pressure of the battery rises and reaches a predetermined pressure due to an abnormal reaction such as overcharging or a short circuit, the explosion-proof valve 3 receives the internal pressure and deforms in the direction of the internal pressure. A shear force is applied to the thin portion 1a integrated with the welding portion 3 to break the thin portion 1a, or the welding portion 5 between the thin portion 1a and the protruding portion 3a of the explosion-proof valve 3 is peeled off, So that the current can be interrupted By keep, it is possible to provide a highly safe explosion-proof sealed battery that can also prevent fire or explosion during overcharge or short circuit.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an explosion-proof sealed battery according to the present invention.

FIGS. 2A and 2B are enlarged views of a lead member mounting member used for the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 2A is a plan view and FIG.

3 is an enlarged view of an explosion-proof valve used for the explosion-proof sealed battery shown in FIG. 1, wherein (a) is a plan view and (b) is a longitudinal sectional view.

FIG. 4 is an enlarged cross-sectional view showing a thin portion of a lead member attaching member used in the explosion-proof sealed battery shown in FIG. 1 and its periphery.

FIG. 5 is a longitudinal sectional view of an essential part showing an enlarged state in which the explosion-proof valve of the battery shown in FIG. 1 is deformed in the direction of the internal pressure in response to the internal pressure of the battery and the thin portion provided on the lead member attaching member is broken.

FIG. 6 is an enlarged view showing a state in which the explosion-proof valve of the battery shown in FIG. 1 is deformed in the direction of the internal pressure in response to the internal pressure of the battery, and the welded portion between the projecting portion of the explosion-proof valve and the thin portion of the lead member attaching member is separated. It is a principal part longitudinal cross-sectional view.

FIG. 7 is a diagram illustrating a relationship between a charging time, a battery voltage, a charging current, and a battery temperature when an overcharge test of the battery according to the embodiment of the present invention is performed.

FIG. 8 is a longitudinal sectional view of a main part of a conventional explosion-proof sealed battery.

9A and 9B are diagrams showing a main part of a battery case used for a conventional explosion-proof sealed battery, wherein FIG. 9A is a bottom view and FIG. 9B is a longitudinal sectional view.

FIG. 10 is an enlarged cross-sectional view showing a thin portion of a lead member attaching member having a different configuration from the present invention and its periphery.

FIG. 11 is an enlarged cross-sectional view showing a thin portion of a lead member attaching member having a different configuration from the present invention and its periphery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead member attaching member 1a Thin portion 1b Pressure inlet 2 Terminal plate 2a Gas exhaust hole 3 Explosion-proof valve 3a Projection 4 Insulation packing 5 Welded part 6 Battery case 7 Annular gasket 8 Lead body 9 Positive electrode 10 Negative electrode 11 Separator 12 Electrolyte

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 2/34 H01M 2/12 101 H01M 10/40

Claims (1)

(57) [Claims] 1. A projecting portion 3a of an explosion-proof valve 3, which is deformed in the direction of internal pressure as the battery internal pressure rises, and a thin portion 1a provided on a lead body attaching member 1 are welded, and a lead is attached to the lead body attaching member 1. An explosion-proof sealed battery to which the body 8 is attached, wherein the thin portion 1a is provided on an inner side from both end surfaces in the thickness direction of the lead member mounting member 1.