KR20080018471A - Rechageable battery - Google Patents

Abstract

A secondary battery is provided to prevent shortage when a positive electrode tap comes in contact with a case, thereby improving the stability of a secondary battery. A secondary battery comprises an electrode assembly which is connected with an electrode tap; a case which accommodates the electrode assembly; and a cap assembly(30) which seals the upper aperture of the case, wherein the electrode tap comprises a contact bonding part(13) which is electrically connected with the lower end of the cap assembly and is formed at one part, and a shortage intercepting part(14) which is coated on the other part, comprises an insulating material and prevents the shortage of the electrode tap and the case.

Description

Secondary Battery {RECHAGEABLE BATTERY}

1 is a partial longitudinal cross-sectional view of a cylindrical secondary battery according to an embodiment of the present invention.

Figure 2a is a schematic cross-sectional view of the positive electrode tab before bending according to an embodiment of the present invention.

2B is a schematic cross-sectional view of the positive electrode tab after bending according to the embodiment of the present invention.

Figure 3a is an embodiment of an upper insulating plate according to an embodiment of the present invention.

Figure 3b is another embodiment of the upper insulating plate according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

11: Anode plate 12: Anode tab

13: Contact coupling part 14: Short circuit blocking part

15: Center pin 20: Case, can

21: Beading part 22: Crimping part

30: cap assembly 31: safety band

32: current breaker 33: positive temperature element

34: Cap 35: Gasket

40: upper insulating plate 41: electrolyte passage

42: tap-out outlet 43: short circuit prevention member

The present invention relates to a cylindrical secondary battery, and more particularly, to a cylindrical secondary battery having improved stability of a secondary battery by forming a short circuit breaker coated with an insulating material on a positive electrode tab connected to an electrode assembly.

In general, secondary batteries are batteries that can be used repeatedly if they are recharged, unlike disposable batteries, and their main uses are for communications such as mobile phones, PCS, wireless systems, information processing such as laptops, PDAs, and camcorders and digital cameras. For audio and video. The main reason for the recent interest in secondary batteries and rapid development is that secondary batteries are power sources having ultra-light weight, high energy density, high output voltage, low self discharge rate, environmental friendliness, and long lifespan.

Secondary batteries are divided into nickel-hydrogen (Ni-MH) batteries and lithium-ion (Li-ion) batteries according to electrode active materials. Lithium-ion batteries, in particular, use a liquid electrolyte or a solid polymer electrolyte or gel depending on the type of electrolyte. It can be divided into the case of using the electrolyte of the phase. Generally, a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. In addition, the lithium ion battery is divided into various types such as a cylindrical or square can type and a pouch type according to the shape of a container in which the electrode assembly is accommodated.

Lithium-ion batteries have a much higher energy density per weight than disposable batteries, making it possible to realize ultra-light batteries. The average voltage per cell is 3.6V, which is three times more compact than other secondary batteries such as Ni-Cd or Ni-MH batteries. It works. In addition, the lithium ion battery has a self-discharge rate of less than 5% per month at 20 ° C, which is about one third of that of a nickel-cadmium battery or nickel-metal hydride battery, and is environmentally friendly by not using heavy metals such as cadmium (Cd) or mercury (Hg). In addition, there is an advantage that can be charged and discharged 1000 times or more in a normal state. Therefore, on the basis of these advantages, with the recent development of information and communication technology, the development is rapidly made.

In general, a cylindrical secondary battery includes an electrode assembly, a cylindrical can in which the electrode assembly is accommodated, and a cap assembly coupled to an upper portion of the cylindrical can.

The electrode assembly is manufactured by winding a cylindrical plate after a positive electrode plate coated with a positive electrode active material, a negative electrode plate coated with a negative electrode active material, and a separator. In this case, a positive electrode tab is electrically connected to the positive electrode plate, and a negative electrode tab is electrically connected to the negative electrode plate, respectively.

The cylindrical electrode assembly is accommodated in a cylindrical can and fixed to prevent the electrode assembly from being separated. Then, an electrolyte is injected into the cylindrical can and sealed with a cap assembly to complete a cylindrical secondary battery.

Meanwhile, a lower insulating plate is inserted to insulate the electrode assembly from the cylindrical can before inserting the electrode assembly into the cylindrical can. In addition, the upper insulating plate is inserted to insulate the electrode assembly from the cap assembly after the electrode assembly is inserted and before sealing the cap assembly. In addition, a center pin is inserted into the center of the wound electrode assembly in order to prevent deformation of the electrode assembly and use it as a discharge passage of gas generated inside the battery.

Typically, as the center pin is inserted, the degree of adhesion between the electrode assembly and the can is further increased, and the electrode assembly itself is also compressed. In this case, since the impregnation rate of the electrolyte is further lowered, it is advantageous to insert the center pin after the electrolyte injection process in order to improve the impregnation of the electrolyte.

On the other hand, the positive electrode tab connected to the positive electrode plate is drawn out to the upper electrode assembly, and also connected to the cap assembly through the upper insulating plate. In this case, the positive electrode tab may be bent at a predetermined angle to contact the can with the bent surface charged with the negative electrode. Accordingly, there is a problem that a short circuit of the secondary battery occurs, which may seriously affect the stability of the secondary battery.

Accordingly, an object of the present invention is to provide a secondary battery having improved stability by forming a short circuit breaker on one surface of a positive electrode tab.

Another object of the present invention is to provide a secondary battery having improved stability, including an upper insulating plate provided with a short circuit prevention member on an electrode assembly.

In order to achieve the above object, the secondary battery according to the present invention includes an electrode assembly to which an electrode tab is connected, a case in which the electrode assembly is accommodated, and a cap assembly sealing a top opening of the case, wherein the electrode tab is A contact coupling part electrically connected to the lower end of the cap assembly on one side and a short circuit blocking part to be coated with an insulating material on the other side to prevent a short circuit between the electrode tab and the case are included.

In addition, the short circuit breaker may be formed by coating an insulating material on one surface of the electrode tab.

In addition, the short circuit breaker may be formed by coating an insulating material on the bent outer circumferential surface of the electrode tab facing the case.

In addition, the electrode tab may be formed of a positive electrode tab.

In addition, the insulating material may be formed of PET (Polyester) or PI (Polyimide) material.

In addition, the insulating material may be formed of an insulating tape.

In addition, the insulating material may be formed of a polymer resin solution that is compression molded to the electrode tab.

In addition, the polymer resin solution may be made of polyethylene (PE), polypropylene (PP), amorphous polyamide (Amorphous Polyamid) series.

In addition, the secondary battery may include an upper insulating plate on which the tab inlet through which the electrode tab passes is formed on the electrode assembly.

In addition, the upper insulating plate may have a short circuit preventing member surrounding the outer periphery of the tab outlet and preventing a short circuit between the electrode tab and the case.

In addition, the short-circuit prevention member may be formed as a circular jaw protruding upward.

In addition, the short-circuit prevention member may be formed as a multi-layer protruding upwards.

Hereinafter, a secondary battery according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a secondary battery according to an embodiment of the present invention includes an electrode assembly in which an electrode tab is connected to a cylindrical secondary battery, a case 20 in which the electrode assembly and an electrolyte are accommodated, and the case ( The cap assembly 30 for sealing the opened upper portion of the 20), the upper insulating plate 40 is provided on the electrode assembly and the lower insulating plate (not shown) is provided below the electrode assembly.

The electrode assembly is interposed between the positive electrode plate 11, the negative electrode plate, the positive electrode plate 11 and the negative electrode plate to insulate the positive electrode plate 11 and the negative electrode plate is wound in a jelly roll shape is formed in a cylindrical shape.

The positive electrode plate 11 includes a positive electrode current collector made of aluminum foil, which is a metal thin plate having excellent conductivity, and a positive electrode active material coated on both surfaces of the positive electrode current collector. Both ends of the positive electrode plate 11 are formed with a positive electrode non-coating portion is not coated with a positive electrode active material, the electrode tab of the aluminum material protruding to the top of the electrode assembly is connected to one end of the positive electrode.

The electrode tab is a positive electrode tab 12, the positive electrode tab 12, as shown in Figure 2a, the contact coupling is electrically connected to the safety vent 31 to be described later, the lower end of the cap assembly 30 on one side A portion 13 is formed, and a short circuit breaker 14 is formed on the other side of the cathode tab 12 to prevent the short circuit between the positive electrode tab 12 and the case 20.

The short circuit breaker 14 is formed by coating an insulating material on one surface of the positive electrode tab 12. As illustrated in FIG. 2B, the bent outer circumferential surface of the positive electrode tab 12 facing the case 20 is formed. It is preferable that it is formed by coating an insulating material. In this case, the short circuit breaker 14 may be formed by coating an insulating material on the entire outer circumferential surface of the positive electrode tab 12 regardless of the bent surface of the positive electrode tab 12.

Meanwhile, the insulating material coated to form the short circuit breaker 14 of the positive electrode tab 12 may be formed of PET (Polyester) or PI (Polyimide) material or may be formed of an insulating tape.

In addition, the insulating material may be formed of a polymer resin solution that is compression molded on the electrode tab. The polymer resin solution may be formed of polyethylene (PE), polypropylene (PP), and amorphous polyamide (Amorphous Polyamid).

The negative electrode plate includes a negative electrode current collector made of copper or nickel foil, which is a conductive metal thin plate, and a negative electrode active material coated on both surfaces of the negative electrode current collector. Both ends of the negative electrode plate are provided with a negative electrode non-coating portion is not coated with a negative electrode active material, the negative electrode tab of the nickel material protruding to the lower portion of the electrode assembly is connected to one end of the negative electrode.

On the other hand, the electrode assembly is configured to include a center pin 15 therein.

The center pin 15 is inserted into a space formed at the center of the electrode assembly to prevent loosening of the wound electrode assembly and to facilitate the movement of gas generated inside the battery.

The case 20 is formed of a cylindrical can 20. That is, a cylindrical side plate and a bottom plate sealing the lower portion of the cylindrical side plate is formed so as to form a space for accommodating the cylindrical electrode assembly therein, the upper portion of the cylindrical side plate to insert the electrode assembly For opening. Since the negative electrode tab of the electrode assembly is bonded to the center of the lower plate of the cylindrical can 20, the cylindrical can 20 itself forms a negative electrode. In addition, the cylindrical can 20 is generally formed of a lightweight conductive metal material such as aluminum (Al), iron (Fe), or an alloy thereof, and is also formed by a processing method such as deep drawing.

The cylindrical can 20 is formed with a crimping portion 22 which is bent from the top to the inside to press the upper portion of the cap assembly 30 coupled to the opened upper portion. In addition, the cylindrical can 20 is recessed inward to press the lower portion of the cap assembly 30 at a position spaced apart from the crimping portion 22 by a distance corresponding to the thickness of the cap assembly 30. Beaded portion 21 is further formed.

On the other hand, the cylindrical can 20 accommodates the electrolyte that enables the movement of lithium ions in the electrode assembly together with the electrode assembly therein.

The electrolyte serves as a moving medium of lithium ions generated by an electrochemical reaction in the positive and negative electrodes inside the battery during charging and discharging, and may be a non-aqueous organic electrolyte which is a mixture of lithium salts and high purity organic solvents. In addition, the electrolyte may be a polymer using a polymer electrolyte, and the type of the electrolyte material is not limited thereto.

The cap assembly 30 includes a safety vent 31, a current interrupter (CID) 32, a positive thermal coefficient (PTC) 33, a conductive cap up 34, It consists of an insulating gasket 35.

The safety vent 31 is formed in a plate shape and a central portion protrudes downward to be electrically connected to the contact coupling part 13 of the positive electrode tab 12 described above. On the other hand, it is a matter of course that the central portion protruding downward by the pressure generated in the interior of the overcharge or secondary battery may be deformed in the upper direction.

The current breaker 32 is electrically connected to the upper portion of the safety vent 31, and the central portion of the safety vent 31 is broken by being convexly deformed upward by the internal pressure to break the internal circuit.

The positive temperature element 33 is electrically connected to the upper portion of the current circuit breaker 32 and the internal circuit is cut off at a predetermined temperature or more to block the flow of current in the battery by overheating the battery.

The cap up 34 has an electrode terminal provided on the positive temperature element 33 and formed convexly so as to be electrically connected to an external device.

The insulating gasket 35 is formed to surround the side circumference of the safety vent 31, the current breaker 32, the positive temperature element 33, and the cap up 34, and the respective elements are formed from the cylindrical can 20. Insulate them.

The upper insulating plate 40 is installed on the electrode assembly to avoid contact between the electrode assembly and the cap assembly 30. As shown in FIGS. 3A and 3B, an electrolyte passage opening 41 and a tap outlet port are provided. 42 and a short circuit prevention member 43 are included.

The electrolyte passage opening 41 is formed with at least one passage through which the electrolyte flows, and the tab outlet 42 is a passage through which the positive electrode tab 12 connected to the electrode assembly penetrates through the positive electrode tab ( The contact coupling part 13 of 12 is electrically connected to the safety vent 31 as described above. In addition, the gas generated in the electrode assembly may be discharged through the electrolyte passage opening 41 and the tab outlet 42.

The short circuit preventing member 43 has a case 20 in which the positive electrode tab 12 is charged with a negative electrode when the positive electrode tab 12 drawn to the upper portion of the electrode assembly is electrically coupled to the cap assembly 30. It is formed integrally on the upper surface of the upper insulating plate 40 to prevent a short circuit in contact with the contact and is formed in a jaw shape protruding a predetermined length upward. In this case, the short circuit preventing member 43 is formed to surround the outer periphery of the tab outlet 42 so that the tab outlet 42 is located inside the short circuit preventing member 43.

As shown in FIG. 3A, the short circuit preventing member 43 is formed on the upper surface of the upper insulating plate 40 and is formed of a circular jaw protruding a predetermined length upward. On the other hand, the short circuit prevention member 43 may be made of a multi-jaw, as shown in Figure 3b.

The lower insulating plate (not shown) is provided between the negative electrode tab portion bent so that the lower surface of the electrode assembly is not short-circuited with the bottom surface of the cylindrical can 20 and the lower surface of the electrode assembly. At this time, the lower insulating plate (not shown) has a circular shape and a hole is formed on one side for the negative electrode tab of the electrode assembly to pass.

Next, the operation of the secondary battery according to the exemplary embodiment of the present invention configured as described above will be described.

First, the electrode assembly to which the electrode tab is connected is wound into a jelly roll type and inserted into the cylindrical case 20. After the upper insulating plate 40 is seated on the electrode assembly, the case 20 allows the gasket 35 to be seated on the upper end of the case 20 while the jelly roll-type electrode assembly is inserted into the case 20. The beading part 21 is formed by applying a predetermined pressure from the outer wall of the.

As shown in FIG. 1, the upper insulating plate 40 has a tab outlet 42 through which the positive electrode tab 12 is drawn out, and a short circuit preventing member 43 surrounding the outer circumference of the tab outlet 42. ) Is integrally formed. The short circuit preventing member 43 has a jaw shape protruding upwards, as shown in FIGS. 3A and 3B, and includes a rounded jaw or a polygonal jaw, and contacts or comes into close contact with an end portion of the gasket 35. 12) and the short circuit of the case 20 is primarily prevented.

Next, the electrolyte is injected into the case 20 and the gasket 35 is inserted. The gasket 35 is seated on the upper surface of the beading portion 21, and the positive electrode tab 12 connected to the positive electrode plate 11 of the electrode assembly is electrically connected to the bottom surface of the safety vent 31, and is not shown. The negative electrode tab connected to the negative electrode plate of the electrode assembly is electrically connected to the case 20 through another process.

On the other hand, the positive electrode tab 12 has a contact coupling portion 13 which is electrically connected to the safety vent 31 on one side, the positive electrode tab 12 is a safety vent 31 by the contact coupling portion (13). Is electrically connected). On the other hand, the positive electrode tab 12 is bent and deformed and connected to the safety vent 31, wherein the bent portion of the positive electrode tab 12 may be in contact with the case 20 charged with the negative electrode, accordingly, Short circuiting of the secondary battery may occur.

In the positive electrode tab 12 according to the exemplary embodiment of the present invention, a short circuit blocking part 14 is formed at the other side of the contact coupling part 13. That is, the outer circumferential surface in the bending direction of the positive electrode tab 12, that is, the outer circumferential surface opposite to the case 20 of the bent positive electrode tab 12 is coated with an insulating material, as shown in FIGS. 2A and 2B. The short circuit break part 14 is formed. In this case, the short circuit breaker 14 may be formed by coating an insulating material on one outer circumferential surface of the positive electrode tab 12 as in the present exemplary embodiment, or may be formed by coating an insulating material on the entire outer circumferential surface of the positive electrode tab 12. It may be. Accordingly, the short circuit breaker 14 may cause a short circuit caused by contact between the case 20 and the positive electrode tab 12, which may occur when the positive electrode tab 12 is electrically connected to the safety vent 31. Prevent secondary.

Thereafter, the cap assembly 30 is disposed, the secondary battery is sealed through a crimping process, and the overall height of the secondary battery is maintained constant through the pressing process.

According to the above process, a secondary battery according to an embodiment of the present invention is completed.

The present invention is not limited to the technical spirit of the specific embodiments or drawings described above, and those skilled in the art without departing from the gist of the invention claimed in the claims Various modifications are possible, of course, and such changes are within the scope of the claims of the present invention.

As described above, the present invention has the effect of improving the stability of the secondary battery by forming a short circuit breaker coated with an insulating material on one surface of the positive electrode tab to prevent a short circuit when contacting the positive electrode tab and the case.

Another effect of the present invention is to improve the stability of the secondary battery, including an upper insulating plate provided with a short circuit prevention member to prevent a short circuit between the positive electrode tab and the case on the electrode assembly.

Claims (12)

A secondary battery comprising an electrode assembly to which an electrode tab is connected, a case in which the electrode assembly is accommodated, and a cap assembly to seal an upper end opening of the case, The electrode tab, A contact coupling part electrically connected to a lower end of the cap assembly at one side; And The secondary battery is coated with an insulating material on the other side to include a short-circuit blocking unit for preventing a short circuit of the electrode tab and the case. The method of claim 1, The short circuit breaker, Secondary battery characterized in that the insulating material is coated on one surface of the electrode tab is formed. The method according to claim 1 or 2, The short circuit breaker, Secondary battery, characterized in that the insulating material is coated on the bent outer peripheral surface of the electrode tab facing the case. The method of claim 1, The electrode tab, A secondary battery comprising a positive electrode tab. The method of claim 1, The insulation material, Secondary battery, characterized in that formed of PET (Polyester) or PI (Polyimide) material. The method of claim 1, The insulation material, The secondary battery is formed of an insulating tape. The method of claim 1, The insulation material, The secondary battery is formed of a polymer resin solution that is compression molded to the electrode tab. The method of claim 7, wherein The polymer resin solution, A secondary battery comprising polyethylene (PE), polypropylene (PP), and amorphous polyamide (Amorphous Polyamid) series. The method of claim 1, The secondary battery, And an upper insulating plate having a tap-out port through which the electrode tab penetrates the electrode assembly. The method of claim 9, The upper insulating plate, A secondary battery, characterized in that a short circuit prevention member is formed around the outer periphery of the tab outlet and prevents a short circuit between the electrode tab and the case. The method of claim 10, The short circuit prevention member, Secondary battery, characterized in that formed in a circular jaw protruding upward. The method of claim 10, The short circuit prevention member, A secondary battery, characterized in that formed by a multi-jaw protruding upward.

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