JP3083873U - Explosion-proof safety structure of cylindrical lithium battery - Google Patents

Abstract

An object of the present invention is to provide a safety structure for preventing explosion of a cylindrical lithium battery, in particular, a safe explosion prevention structure for preventing the battery from firing or exploding due to overcharging. SOLUTION: When the lithium battery is overcharged, the temperature inside the battery rises sharply and the pressure rises, but when the temperature rises sharply, the resistance value of the resistor plate having a positive temperature coefficient of resistance doubles. Current flowing therethrough is suppressed. If the temperature continues to rise, the electrolyte starts to gasify, the internal pressure in the battery rises and exceeds the pressure that a thin part of the breaker sheet can withstand, the thin part is broken and the charging circuit is opened, and charging stops. I do. Also, when the increased battery internal pressure exceeds the break pressure of the safety valve, the safety valve ruptures and the pressure is released.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a safety structure for preventing explosion of a cylindrical lithium battery, and more particularly, to a structural design for ensuring safety in use of a lithium battery provided with multiple safety devices such as a circuit release and a pressure release.

[0002]

[Prior art]

 As is generally known, lithium secondary batteries have advantages such as large capacity and light weight, and are currently the most common in the secondary battery market. However, when the lithium secondary battery is overcharged due to prolonged charging, the electrolyte in the battery is decomposed, causing a sharp rise in the temperature inside the battery and an accompanying increase in the internal pressure, resulting in ignition or explosion. There is a danger of doing. Conventional lithium secondary batteries have an explosion prevention mechanism, but it has not been easy to increase the capacity of the battery because the explosion prevention mechanism is too thick and takes up too much space. Further, although such an explosion prevention mechanism has a prevention function, it has drawbacks such as a high production cost, a large number of components, and a large volume, which has hindered the development of a high-capacity lithium battery.

[0003]

[Problems to be solved by the invention]

 In view of the drawbacks of the conventional lithium battery, the present invention discloses an improvement in a safer, cheaper, and more compact explosion-proof structure developed through intensive research.

The main object of the present invention is to provide an improved structure of a cylindrical lithium battery which is safe and can prevent explosion. In the present invention, a break in the thin portion of the battery breaker sheet causes the charging circuit to open. Also, when the internal pressure of the battery is too high, the intended pressure release is achieved by breaking the safety valve. In the meantime, the battery stops overcharging, preventing ignition and gas explosion of the battery.

[0005]

[Means for Solving the Problems]

 The explosion-proof safety structure of the cylindrical lithium battery according to the present invention has a relatively thin thickness provided with one downward conductive stem connected to the positive (+) pole of the battery. A breaker seat having a central portion, a ring-shaped configuration, an insulating ring disposed between the safety valve and the breaker seat, a central portion connected to the breaker seat by laser welding, and a bottom side having a flange. It is formed so that the insulating ring and the breaker sheet can be fixed, and after being riveted to the side sheet, a positive temperature coefficient of resistivity board (hereinafter abbreviated as PTC board) A safety valve provided with a ring-shaped groove capable of fixing the top cover of the positive electrode and the polyimide insulating sheet; A positive electrode lid with vent holes, a ring-shaped polyimide insulating sheet, and a thin part at the center of the breaker sheet, the center of the safety valve and the laser. When the battery is connected by welding and the pressure of the battery is exceeded, the thin part is broken and the charging circuit is opened, and a ring-shaped groove is provided at the center of the safety valve, and the structure of the groove withstands pressure. When it is no longer possible, the groove is broken and pressure release can be achieved.

[0006] When a lithium battery is overcharged, the temperature inside the battery rises sharply and the pressure rises. When the temperature rapidly rises in this way, the resistance value of the resistance plate (PCT plate) having a positive temperature coefficient of resistance is doubled, and the flowing current is suppressed. If the temperature continues to rise, the electrolyte starts to gasify, the internal pressure in the battery rises, exceeding the allowable range for thin parts of the breaker sheet, the thin parts are broken, the charging circuit is opened, and charging stops. I do. However, since these current suppressing or interrupting mechanisms cannot release the pressure, the increased internal battery pressure is released when the pressure exceeds the break pressure of the safety valve and the safety valve ruptures.

[0007]

[Embodiment of the invention]

 As shown in FIG. 1, in the battery structure of the present invention, a ring-shaped polyimide insulating sheet 6 is provided on an upper lid 1 when viewed from above and a current protection plate 2 is provided at the bottom of the upper lid. It is installed in. The polyimide insulating plate 6, the upper lid 1 and the current protection plate 2 are all installed in a ring-shaped flange provided above the safety valve 3. The insulating ring 4 is installed at the bottom of the safety valve 3, and the breaker seat 5 is installed further below. Said breaker sheet 5 comprises a thin section and a conductive stem 12. The center of the bottom of the safety valve 3, which is the conduction point E at the bottom of the safety valve 3 (see also FIG. 3), is firmly connected to the center of the breaker seat 5 by laser welding. The sealing insulating ring 9 is installed on the bottom of the breaker sheet 5. All the components are finally installed inside the upper part of the battery shell 7, the upper end of the battery shell 7, the safety valve 3 and the sealing insulating ring 9 are provided with a sealing machine. It is sealed and fixed by pressing it inward and bending it 90 degrees. FIG. 2 shows a preferred embodiment of the battery thus manufactured.

In FIG. 2, which shows a functional structure in a normal state, a positive power source in the battery shell is connected to a positive conductive sheet 8, a conductive stem 12, a center point of the breaker seat 5, and a conductive point E at the bottom of the safety valve 3. Through the safety valve 3, the PCT plate 2 (current protection plate) and the upper lid 1.

As shown in FIG. 3, in an overcharged state, the electrolytic solution is decomposed into a gas, and the internal pressure is increased. The internal pressure of the gas pushes the safety valve 3 upward through the vent hole of the breaker seat 5. Meanwhile, the conductive point E at the bottom of the safety valve 3 is firmly fixed to the center of the breaker seat 5 by laser welding. When the internal pressure reaches a certain level P1, the thin portion of the breaker seat 5 breaks from the pressure rupture starting point A of the safety valve to the pressure rupture end point B, and at the same time (see FIG. 4) the bottom of the safety valve 3 is pushed upward by the internal pressure. The circuit can be peeled off from the breaker sheet 5 and protruded upward to open the circuit.

As shown in FIG. 3, the bottom of the safety valve 3 is provided with two ring-shaped grooves. The positions of these grooves are substantially adjacent to each other, and when an internal pressure of a certain level or more is applied, One is torn first. If the internal pressure continues to rise until the internal pressure reaches the allowable limit P2 at the corner of the ring-shaped groove, the safety valve will rupture from the pressure-bursting starting point C at the corner of the ring-shaped groove to the pressure-bursting end point D. At the same time (see FIG. 5), the gas passes from the rupture point at the bottom of the safety valve 3 to the outside of the battery through the hole of the ring-shaped PTC plate 2 (current protection plate) and the vent hole 10 of the upper lid. Escape and achieve the desired pressure relief.

[Brief description of the drawings]

FIG. 1 is an exploded view showing a structure of a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a structure of a battery when not in use or when charging or discharging normally in a preferred embodiment of the present invention.

FIG. 3 is a partially enlarged view of FIG. 2, showing in detail the structure of a battery protected by opening a circuit when not in use or during normal charging or discharging.

FIG. 4 is a structural view of a battery in which a circuit is opened due to an abnormal increase in internal pressure according to a preferred embodiment of the present invention;

FIG. 5 is a structural view of a battery according to a preferred embodiment of the present invention with an internal high-pressure gas released due to an abnormal increase in internal pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper lid 2 Resistance plate with a positive temperature coefficient of resistance (abbreviated PTC plate) 3 Safety valve 4 Insulation ring 5 Breaker sheet 6 Polyimide insulation sheet 7 Battery shell 8 Positive (+) pole conduction plate 9 Sealing insulation ring 10 Ventilation hole of upper lid 11 Vent hole of breaker seat 12 Conductive stem of breaker seat A Start point of rupture of breaker sheet B End point of rupture of breaker sheet C Start point of rupture of safety valve D End point of rupture of safety valve E Conduction point at bottom of safety valve P Battery Normal pressure inside the battery P1 Abnormal pressure inside the battery P2 Abnormal pressure inside the battery

Claims (1)

[Utility model registration claims] A breaker sheet having a relatively thin center portion provided with one downwardly directed conductive stem connected to the positive (+) pole of the battery; An insulating ring installed between the safety valve and the breaker seat, and a center portion connected to the breaker seat by laser welding,
The bottom side is formed so that the insulation ring and the breaker sheet can be fixed with a flange, and after being riveted to the side sheet, a resistance plate having a positive temperature coefficient of resistance, a top cover of the positive electrode, and a polyimide insulation sheet A safety valve with a ring-shaped groove, a ring-shaped resistance plate with a positive temperature coefficient of resistance, a positive lid with ventilation holes, and a ring-shaped polyimide insulating sheet. The thin portion at the center of the breaker seat is connected to the center of the safety valve by laser welding, and when the pressure of the battery is exceeded, the thin portion is broken and the charging circuit is opened, and furthermore, the center of the safety valve is opened. A ring-shaped groove is provided so that when the structure of the groove cannot withstand pressure, the groove can be broken to achieve pressure release. An explosion-proof safety structure for cylindrical lithium batteries.