JPH08321293A - Non-aqueous electrolyte battery - Google Patents

Abstract

PURPOSE: To prevent rupture and present a safe continuous service for a long period of time by furnishing a reversible valve and a rupture valve, discharging the gas by the reversible valve in the case of low internal pressure, and thereby performing a rupture-preventive regulation. CONSTITUTION: A non-aqueous electrolyte battery 1 has a case 3 which accommodates a positive electrode plate, negative electrode plate, separator, and electrolytic solution, wherein the case 3 is equipped with a reversible valve 4 and rupture valve 5. When the internal pressure is below 3kg/cm<2> , the reversible valve 4 is actuated by a valve element 42 made of an elastic material to release the gas filling the inside so that restitution to normal pressure is made. When 3kg/cm<2> is exceeded, the rupture valve is actuated to prevent the case body from rupturing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery such as a lithium secondary battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as portable wireless telephones, portable personal computers and portable video cameras have been developed, and various electronic devices have been miniaturized to a portable size. Along with this, as a built-in battery, a battery having a high energy density and being lightweight is adopted. A typical battery that satisfies such requirements uses a lithium-based material such as lithium metal, a lithium alloy, or carbon that holds lithium ions as a negative electrode active material, and reversibly generates electric power reversibly with lithium ions like a lithium-cobalt composite oxide. A lithium secondary battery in which a compound that chemically reacts is used as a positive electrode active material, and an aprotic organic solvent in which a lithium salt such as LiCIO ₄ or LiPF ₆ is dissolved is used as an electrolytic solution.

A lithium secondary battery holds a negative electrode plate formed by holding a negative electrode active material on a negative electrode current collector, a positive electrode plate formed by holding a positive electrode active material, and an electrolytic solution and between the negative electrode plate and the positive electrode plate. A sheet-like electrode group consisting of a separator for preventing a short circuit between both electrodes is spirally wound and housed in a cylindrical or prismatic case.

By the way, when a battery of this kind is unexpectedly exposed to a high temperature, or the temperature of the battery suddenly rises due to an external short circuit or an internal short circuit due to deterioration of an electrode group, or overdischarge or overcharge, the electrolytic solution volatilizes or Decomposes and gasifies. As a result, the internal pressure of the case rises, the case expands and deforms or bursts, and the device equipped with the battery is damaged. Since the electrolyte is a flammable organic solvent, it causes a fire and is in a dangerous state.

Therefore, as a measure to prevent the battery from bursting, a gas vent hole is formed in the battery case, and a thin metal plate is welded and hermetically sealed therein. When the internal pressure rises, only the thin plate bursts and gas escapes. Such an irreversible valve (rupture valve) structure has been proposed.

Further, in the case of a non-aqueous electrolyte battery, since the Coulomb efficiency is almost 100%, the electrolyte does not decrease even after repeated charging, and it is necessary to prevent the infiltration of water from the outside. However, it has been said that the burst valve as described above is preferable.

[0007]

However, in reality, if the internal pressure is below a certain level, the battery case will not burst, and
Even if it deforms, it stays small elastic deformation at best,
It proved to be safe to use continuously. And, even if the internal pressure is slightly increased, it can save resources if it can be continuously used safely. Therefore, an object of the present invention is to provide a non-aqueous electrolyte battery that can be safely used for a long time and is suitable for resource saving measures.

[0008]

In order to achieve the above object, a non-aqueous electrolyte battery of the present invention has a positive electrode plate, a negative electrode plate, and an electrolyte solution held between the positive electrode plate and the negative electrode plate. A separator that intervenes to prevent a short circuit between both electrodes, a positive electrode plate,
A non-aqueous electrolyte battery comprising a case containing a negative electrode plate and a separator, wherein the aprotic organic solvent is a component of the electrolytic solution, wherein the case is provided with a reversible valve and a burst valve. .

In this non-aqueous electrolyte battery, when the positive electrode plate, the negative electrode plate and the separator are spirally wound, the reversible valve is provided on the surface intersecting the axis of the winding core. desirable. When the internal pressure is 3 kg / cm ² or less, only the reversible valve operates and the internal pressure is 3 kg / cm ²
The rupture valve should also be designed to operate when the temperature exceeds.

[0010]

[Function] Since the battery case is equipped with a reversible valve and a burst valve, only the reversible valve opens and the inside of the case is filled until the internal pressure of the case reaches a certain value (internal pressure). When the gas is released and the pressure returns to normal pressure, the reversible valve closes. Therefore, if the predetermined internal pressure at which the reversible valve operates is designed so that the expansion deformation of the battery is elastic deformation and that the devices around the battery are not damaged by the deformation, then the battery will be used in the same manner as before the internal pressure was raised. Can be used. Further, when the internal pressure exceeds a certain value, the burst valve also operates, suppressing a radical increase in the internal pressure so that the gas release rate from the reversible valve cannot catch up. Therefore, the explosion of the battery is prevented.

In the case of a battery in which the positive electrode plate, the negative electrode plate and the separator are spirally wound, gas is generated in the spiral electrode group and moves in the axial direction of the winding core. Therefore, if a reversible valve is provided on the surface that intersects the axis, a small amount of gas that is slowly generated is smoothly dissipated through the reversible valve.

The internal pressure of the battery, which affects the electrode group, battery elements and battery peripherals, is usually higher than 3.5 kg / cm ² , so when the internal pressure is 3 kg / cm ² or less, only the reversible valve operates and the internal pressure increases. When the pressure exceeds 3 kg / cm ² , the burst valve is designed to operate, so that it can be reliably and continuously used.

[0013]

【Example】

First Embodiment A first embodiment of the present invention will be described with reference to the drawings. FIG.
[FIG. 3] is a cross-sectional view showing a non-aqueous electrolyte battery. The non-aqueous electrolyte battery 1 is a cylindrical lithium secondary battery in which a spirally-wound electrode group 2 composed of a positive electrode plate, a negative electrode plate, a separator, and a non-aqueous electrolyte solution is housed in a battery case 3.

The current collector of the positive electrode plate is an aluminum foil having a thickness of 20 μm, and a lithium cobalt composite oxide is held as an active material in the aluminum foil. The positive electrode plate was prepared by mixing polyvinylidene fluoride as a binder and acetylene black as a conductive agent together with an active material to prepare a paste, which was then applied on both sides of a current collector material and dried to a thickness of 180 μm. It was manufactured by rolling into a sheet and cutting into a width of 54 mm.

The negative electrode plate was prepared by mixing graphite as an active material and polyvinylidene fluoride as a binder in the form of a paste on both sides of a current collector made of a copper foil having a thickness of 10 μm, and drying it. And then rolled to a thickness of 220 μm, width 56
It was obtained by cutting into mm.

The separator has a thickness of 25 μm and a width of 58 mm.
The polyethylene microporous membrane of which the electrolytic solution is absorbed. The electrolytic solution is a mixed solution of ethylene carbonate: diethyl carbonate: dimethyl carbonate = 2: 1: 2 (volume ratio) containing 1 mol / l of LiPF ₆ . Battery case 2 has a thickness of 0.3 mm and outer dimensions of 18φ x 6
The surface of a steel body of 3 ^t mm is plated with nickel having a thickness of 5 μm.

These positive electrode plate, separator and negative electrode plate are
After stacking in order, a polyethylene core (not shown) is spirally wound to form a spiral electrode group 2 around the core, and the positive electrode plate is electrically connected to a current collecting washer 21 to form a battery case 3 It is stored in. The negative electrode plate is in contact with the inner surface of the case 3.

The case 3 includes a case body 31, a lid 32 having one through hole at each of the center and the eccentric position, and an eccentricity of the reversible valve 4 and the lid 32 provided so as to close the central through hole of the lid 32. It consists of a rupture valve 5 fixed to seal the through hole at the position.

The reversible valve 4 is attached to the lid 32 as follows. The peripheral edge of the through hole at the center of the lid 32 is sandwiched from above and below by rubber insulating packings 32a and 32b, and a hollow rivet 41 having an inner diameter of 2 mm and having a flange at the upper end is inserted at the center of the insulating packing and is hollow with the lower insulating packing 32b. By pressing the hollow rivet 41 in the axial direction with the current collecting washer 21 in contact with the lower portion of the rivet 41, the inner diameter of the lower end edge of the hollow rivet 41 is enlarged and caulked. Next, the valve body 42 made of an elastic material is placed on the upper surface of the collar of the hollow rivet 41, and the valve body 4 is connected to the cup-shaped metal terminal 43 having the gas vent holes 43a with a diameter of 1 mm at two locations.
The reversible valve 4 is manufactured by resistance welding the terminal 43 and the brim periphery of the hollow rivet 41 while pressurizing 2. The valve body 42 is formed of butyl rubber having a low water permeability, and its surface is covered with a polytetrafluoroethylene resin having a thickness of about 50 μm to prevent deterioration. In addition,
The valve body 42 may be formed of EPDM instead of butyl rubber.

On the other hand, the burst valve 5 is made of a nickel thin plate having a thickness of 5 μm and has an inner diameter of 3 mm at the eccentric position of the lid 32.
Laser welded to the lower edge of the through hole. The burst valve 5 was separately attached to the case 3 not containing the electrode group in the atmosphere, placed in a pressure vessel and gradually pressurized, and it was confirmed that the burst valve 5 burst immediately after exceeding 3 kg / cm ^2. Has been done.

Reversible valve 4, burst valve 5 and current collecting washer 2
1 is attached, the current collecting washer 21 and the positive electrode plate are connected, and then the lid 32 and the case main body 31 are caulked and sealed with the polypropylene gasket 33, whereby a battery having a nominal capacity of 1.2 Ah 1 Is completed.

The battery 1 thus obtained was subjected to normal initial charging and then left in an atmosphere of a temperature of 80 ° C. for 24 hours. When the reversible valve 4 was opened, a gas having an irritating odor was released, and the battery was closed in a few seconds. When the capacity of the battery 1 was measured, it was 70% of the initial capacity.
%, And it was found by visual observation that Case 3 could be continuously used without deformation. Then battery 10
When the current of A was continuously charged for 10 minutes, the burst valve 5 burst.

Second Embodiment A second embodiment of the present invention will be described with reference to the drawings. Figure 2
FIG. 4 is a perspective view showing a case where an electrode group of a non-aqueous electrolyte battery is stored in a battery case. The non-aqueous electrolyte battery 1 is a prismatic lithium secondary battery in which a positive electrode plate 22, a negative electrode plate 23, a separator 24, and a spiral electrode group 2 made of a non-aqueous electrolyte solution are housed in a battery case 3.

The electrode group 2 is of the same quality as in Example 1, except that the positive electrode plate 22 has a thickness of 180 μm and a width of 29 mm, and the separator 24 has a thickness of 25 μm and a width of 33 m.
m, the negative electrode plate 23 has a thickness of 220 μm and a width of 31 mm, and the layers are superposed in order and wound around the polyethylene core in an elliptic spiral shape, and the center line of the core is the case 3 case. It is housed in the battery case 3 so as to be parallel to the opening surface.

The battery case 3 has a thickness of 0.3 mm and inner dimensions of 3
The surface of a 3.1 × 46.5 × 7.5 mm iron main body is nickel-plated with a thickness of 5 μm. The battery case 3 has an opening on one side and a case body 31 provided with a reversible valve 4 on a side surface intersecting with the opening surface, and a positive electrode terminal 6 is fixed in the center by an insulating low-melting glass 32c. , A lid 32 provided with a burst valve 5 at an eccentric position. The reversible valve 4 has the same shape and quality as those of the first embodiment except that the current collecting washer 21 is not fixed, that is, not connected to the positive electrode plate. The burst valve 5 has the same shape and quality as those of the first embodiment. The positive electrode plate 22 is connected to the positive electrode terminal 6 via the positive electrode lead 7. The negative electrode plate 23 is connected to a negative electrode lead (not shown) welded to the lower surface of the lid 32. This battery is sealed by laser welding a lid 32 to a case body 31.

The battery 1 thus obtained was subjected to normal initial charging and then left in an atmosphere of a temperature of 80 ° C. for 24 hours. As a result, the reversible valve 4 was opened, a stimulating odor gas was diffused, and the battery was closed in a few seconds. When the capacity of the battery 1 was measured, it was 70% of the initial value, and it was found that continuous use was possible. Subsequently, when the battery 1 was continuously charged with a current of 10 A for 10 minutes, the burst valve 5 burst.

[0027]

INDUSTRIAL APPLICABILITY As described above, the non-aqueous electrolyte battery of the present invention can be safely and continuously used for a long period of time, and thus is suitable for a battery using a material with few resources.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a non-aqueous electrolyte battery of a first embodiment.

FIG. 2 is a perspective view showing that the electrode group of the non-aqueous electrolyte battery of the second embodiment is housed in a battery case.

[Explanation of symbols]

1 Non-Aqueous Electrolyte Battery 2 Electrode Group 21 Current Collection Washer 22 Positive Plate 23
Negative electrode plate 24 Separator 3 Case 31 Case body 32 Lids 32a, 32b
Insulation packing 32c Low melting point glass 33 Gasket 4 Reversible valve 41 Hollow rivet 42 Valve body 43 Terminal 43a Gas vent hole 5 Burst valve 6 Positive electrode terminal 7 Positive electrode lead

Claims (3)

[Claims] 1. A positive electrode plate, a negative electrode plate, a separator that holds an electrolytic solution and is interposed between the positive electrode plate and the negative electrode plate to prevent a short circuit between both electrodes, the positive electrode plate, the negative electrode plate, and the separator are housed. A non-aqueous electrolyte battery comprising a case and using an aprotic organic solvent as an electrolyte component, wherein the case includes a reversible valve and a burst valve. 2. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode plate, the negative electrode plate and the separator are spirally wound, and the reversible valve is provided on a surface intersecting the axis of the winding core. 3. The non-aqueous electrolyte battery according to claim 1, wherein only the reversible valve operates when the internal pressure is 3 kg / cm ² or less, and the burst valve operates when the internal pressure exceeds 3 kg / cm ^2. .