JP5379048B2 - Secondary battery - Google Patents

Abstract

PURPOSE: A secondary battery is provided to minimize the leak of gas generated by internal abnormality by maximizing the sealability between a cap assembly and a gasket, thereby improving stability and reliability. CONSTITUTION: A secondary battery comprises: an electrode assembly including a positive electrode, a negative electrode, and a separator positioned between two plates; a can for accommodating the electrode assembly through an opening formed at one side thereof; a cap assembly which is located inside the opening of the can and is electrically connected to the electrode assembly; and a gasket which is located between the can and the electrode assembly and has a coating layer having the thickness more than 2 mm at a region which is located with the cap assembly.

Description

  The present invention relates to a secondary battery that maximizes the sealing property between a gasket and a cap assembly, prevents a gas leak that occurs when an internal abnormality occurs, and improves safety and reliability. The present invention relates to a secondary battery.

  Recently, portable electronic / electric devices such as mobile phones, notebook computers, and camcorders have been actively developed and produced so that the portable electronic / electric devices can operate even in places where there is no separate power source. Built-in battery pack. As such a battery pack, a nickel-cadmium (Ni-Cd) battery, a nickel-hydrogen (Ni-MH) battery, and a lithium (Li) battery are typically mentioned from an economical aspect, and charging and discharging are possible. Secondary batteries are generally used.

  Among them, the lithium secondary battery has an operating voltage about three times higher than that of the nickel-cadmium battery or nickel-hydrogen battery, and has a high energy density per unit weight as a battery pack for the portable electronic / electric device. Widely used.

  This lithium secondary battery can be classified into a lithium ion battery using a liquid electrolyte and a lithium polymer battery using a polymer electrolyte depending on the type of electrolyte used, and can be classified into a square type, a cylindrical type and a pouch type according to its shape.

  The cylindrical secondary battery is usually an electrode assembly wound in a cylindrical shape, a can in which an electrolyte is stored so that an opening is formed on one side and lithium ions can move between the electrode assembly, A cap assembly located inside the opening of the can and electrically connected to the electrode assembly and a gasket located between the can and the cap assembly for sealing the can.

  The electrode assembly includes a positive electrode current collector to which a positive electrode active material is applied, a positive electrode plate including a positive electrode tap electrically connected to one side of the positive electrode current collector, and a cathode current collector to which a negative electrode active material is applied And a cathode plate including a cathode tap electrically connected to one side of the cathode current collector, and a separator positioned between the positive electrode plate and the cathode plate.

  The electrolyte is a mixture of a lithium salt and a high-purity organic solvent that serves to move lithium ions generated by an electrochemical reaction from the positive and negative plates of the electrode assembly during charge and discharge. It can be a water-based organic electrolyte or a polymer using a polymer electrolyte.

  In the electrode assembly, a center pin having a main body of a predetermined length is positioned inside the electrode assembly in order to suppress deformation that occurs during charging and discharging, and the main body of the center pin has a length direction inward. A hole is formed to provide a passage for moving gas generated from the periphery of the electrode assembly toward the cap assembly due to overcharge, high-temperature heat exposure, and internal abnormality.

  The cap assembly prevents overheating, ignition and explosion of the secondary battery when an internal abnormality such as overcharging / discharging, high temperature heat exposure, or damage to the electrode assembly due to external impact occurs. And a safety vent formed to be deformed or broken by gas generated from the periphery of the electrode assembly.

  The gasket is for sealing the can so that gas generated due to internal abnormality does not leak to the outside, so that the safety vent of the cap assembly operates normally, and the sealing property of the can In order to improve the above, a coating layer surrounding the gasket is formed along a partial region or outer peripheral surface.

Korea registered utility model No. 20-0214980 specification Korean Application Publication No. 10-2007-0007537

  In such a secondary battery, in order to improve the sealing performance of the can and prevent the cap assembly from being detached, the end portion of the opening of the can is bent in the direction of the cap assembly. Gas is generated due to an internal abnormality due to the deformation of the gasket located between the can and the cap assembly due to the crimping process, and the sealing between the gasket and the cap assembly is reduced. However, if the safety vent of the cap assembly is necessary due to leakage from between the gasket and the cap assembly, the safety and reliability of the secondary battery may be deteriorated.

  The present invention is for solving the problems of the prior art, wherein the sealing property between the gasket and the cap assembly is maximized, gas leakage caused by internal abnormality is minimized, and safety and reliability are improved. It is an object to provide a secondary battery that improves performance.

  The object of the present invention is to provide an electrode assembly including a positive electrode plate, a cathode plate, and a separator positioned between the two electrode plates, a can having an opening formed on one side thereof and housing the electrode assembly; A cap assembly located inside the opening of the can and electrically connected to the electrode assembly, and located between the can and the cap assembly, the region where the cap assembly is located is 2 mm or more. This is achieved by a secondary battery including a gasket on which a coating layer having a thickness is formed.

  Further, the object of the present invention is to provide an electrode assembly including a positive electrode plate, a cathode plate, and a separator positioned between the two electrode plates, and a can having an opening formed on one side for accommodating the electrode assembly. A cap assembly located inside the opening of the can and electrically connected to the electrode assembly, and located between the can and the cap assembly and coated in a region where the cap assembly is located. The secondary battery includes a gasket on which a layer is formed, and the viscosity of the coating layer is 3000 CPS or more.

  Therefore, in the secondary battery according to the present invention, the coating layer of the gasket located in the region in contact with the cap assembly has a thickness of 2 mm or more, or a coating layer having a viscosity of 3000 CPS or more is formed. Thus, it is possible to minimize gas leakage caused by internal abnormality and improve the safety and reliability of the secondary battery.

1 is an exploded perspective view showing a secondary battery according to a first embodiment of the present invention. It is sectional drawing which shows the secondary battery which concerns on the 1st Embodiment of this invention. 6 is a graph showing a sealing pressure between the cap assembly and a gasket according to a thickness of a coating layer. It is sectional drawing which shows the gasket of the secondary battery which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the other gasket of the secondary battery which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the further another gasket of the secondary battery which concerns on the 1st Embodiment of this invention. It is a separation perspective view showing a rechargeable battery concerning a 2nd embodiment of the present invention. It is sectional drawing which shows the secondary battery which concerns on the 2nd Embodiment of this invention. It is a graph which shows the thickness of the 1 time coating process by the viscosity of a coating layer. 4 is a graph showing a sealing pressure between the cap assembly and a gasket according to a viscosity of a coating layer.

  Detailed description of the object, technical configuration, and operational effects of the present invention can be clearly understood from the following detailed description with reference to the drawings illustrating preferred embodiments of the present invention. For convenience of explanation, the thickness of layers and regions is exaggerated in the drawings, and the illustrated form may be different from the actual one. In addition, when it is described that a part is “connected” to another part, this is not limited to “directly connected”, and other elements are placed between them and “electrically connected” "Is included. Like reference numerals refer to like elements throughout the specification.

<First Embodiment>
FIG. 1A is an exploded perspective view showing a secondary battery according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view showing the secondary battery according to the first embodiment of the present invention.

  As shown in FIGS. 1A and 1B, the secondary battery 100 according to the first embodiment of the present invention includes an electrode assembly 110, an opening formed on one side, and the electrode assembly 110 and an electrolyte (see FIG. 1). (Not shown), a cap assembly 140 positioned inside the opening of the can 130, and a gasket 150 positioned between the can 130 and the cap assembly 140.

  The electrode assembly 110 is electrically connected to a positive electrode current collector (not shown) to which a positive electrode active material (not shown) is applied and one side of the positive electrode current collector, and is directed to the cap assembly 140. A positive electrode plate 111 including a positive electrode tab 114 protruding to the cathode current collector (not shown) to which a cathode active material (not shown) is applied, and electrically connected to one side of the cathode current collector, A cathode plate 112 including a cathode tap 115 protruding in a direction opposite to the positive electrode tab 114 and a separator 113 positioned between the positive electrode plate 111 and the cathode plate 112 are included.

  Here, in the first embodiment of the present invention, it has been described that the positive electrode tab 114 of the electrode assembly 110 protrudes toward the cap assembly 140, but the negative electrode tab 115 of the electrode assembly 110 is The positive electrode tap 114 may protrude in a direction opposite to the negative electrode tab 115.

The positive active _{material, LiCoO 2, LiNiO 2, LiMn} 2 O 4 or _{LiNi 1-x-y Co x} M y O 2 ( where, 0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ x + y ≦ 1 , M can be any of lithium-containing transition metal oxides or lithium chalcogenide compounds typified by metal oxides such as Al, Sr, Mg, La, etc. Crystalline carbon, amorphous carbon, carbon composite, carbon fiber such as carbon fiber, lithium metal, lithium alloy, or the like is used.

  The positive electrode current collector or the cathode current collector is formed of any one selected from the group consisting of stainless steel, nickel, copper, aluminum, and alloys thereof, and more preferably, the positive electrode current collector is aluminum. Alternatively, the cathode current collector is formed of copper or a copper alloy to maximize the efficiency of the electrode assembly 110.

  The separator 113 is located between the positive electrode plate 111 and the negative electrode plate 112 to prevent an electrical paragraph between the positive electrode plate 111 and the negative electrode plate 112, and lithium ions between the two electrode plates. Allow movement. The separator 113 may be formed on a polyolefin-based polymer film such as polyethylene (PE) or polypropylene (PP) or a multilayer film thereof, or may be formed on a porous film including a ceramic material. Both a polymer film and a porous film comprising a ceramic material can be included.

Here, the ceramic material includes silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ) and their insulating nitrides, hydroxides, alkoxys. It can be any one selected from the group consisting of hydrides and ketones.

  The electrode assembly 110 suppresses the deformation of the electrode assembly 110 during charging and discharging, and the main body 122 having a predetermined length on the inner side can be easily moved in the direction of the cap assembly 140 in the event of an internal abnormality. The center pin 120 having the position is located. Here, the main body 122 of the center pin 120 may be formed of an insulating material such as polybutylene terephthalate (PBT), but the gas smoothly moves even in a high temperature state such as overcharge or high temperature heat exposure. For this purpose, it is preferable to use a metal material such as steel, stainless steel (SUS), aluminum, and an aluminum alloy.

  The center pin 120 includes a sealing member 124 that seals the inside of the main body 122 and a fire extinguishing member 125 that is inserted into the main body 122 that is sealed by the sealing member 124 in order to prevent heat generation or ignition due to an internal abnormality. The sealing member 124 may be positioned at both ends of the main body 122 to seal the entire space inside the main body 122, but may be positioned inside the center pin 120 and positioned inside the main body 122. Some areas can be sealed.

  Here, the end portion of the main body 122 of the center pin 120 is bent toward the central portion of the main body 122 in order to prevent the sealing member 124 from being detached from the main body 122.

  The sealing member 124 is formed of a polymer resin such as polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PBT) that can be melted or ruptured by an internal temperature when an internal abnormality occurs. In view of the temperature at which an internal abnormality of a normal secondary battery occurs, it is most preferable to melt or rupture at 100 to 130 ° C.

  The can 130 has an opening at the top and a polygonal column shape at the bottom. The can 130 can accommodate the electrode assembly 110 and the electrolyte. Here, as shown in FIG. 1A, the can 130 may be formed in a columnar shape, and is formed of a light and soft metal material such as aluminum, aluminum alloy, or stainless steel, and is opposite to the positive electrode tap 114. When the cathode tap 115 protruding to the bottom is electrically connected to the lower surface of the can 130, the can 130 preferably serves as a cathode terminal.

  In addition, after sealing the can 130 with the cap assembly 140 and the gasket 150, the can 130 improves the sealing performance of the can 130, and the cap assembly 140 is detached from the can 130 or due to an external impact or the like. In order to prevent the electrode assembly 110 from flowing up and down, a beading portion in which the outer peripheral surface of the can 130 corresponding to the gap between the cap assembly 140 and the electrode assembly 110 is beaded inward by a predetermined distance. A crimping part 137 is formed in which a beading part 135 and the upper end of the can 130 are bent inwardly with respect to the cap assembly 140.

  Here, the secondary battery 100 according to the first embodiment of the present invention includes unnecessary electricity between the electrode assembly 110 and the cap assembly 140 and between the electrode assembly 110 and the can 130. In order to prevent a general connection, the upper insulating plate 117 and the electrode are formed on the electrode assembly 110 and formed with one or a plurality of holes in which gas generated from the periphery of the electrode assembly 110 can move. A lower insulating plate 116 positioned at the lower part of the assembly 110 may be further included.

  The cap assembly 140 is located inside the opening of the can 130 and is electrically connected to a cap-up 141 that is electrically connected to an external terminal (not shown) and a positive electrode tap 114 of the electrode assembly 110. A safety vent 142 that is deformed or ruptured when the internal pressure exceeds a predetermined level by the gas generated from the periphery of the electrode assembly 110, and is positioned on the safety vent 142. A current interrupt device (CID) 143 that is broken or broken by the safety vent 142 that is deformed or ruptured according to an internal pressure to cut off an electrical connection between the electrode assembly 110 and an external terminal. including.

  Here, the cap assembly 140 has an annular shape positioned between the current interrupt device 143 and the cap-up 141 in order to prevent an overcurrent from flowing between the electrode assembly 110 and the external terminal. The PTC thermistor (Positive Temperature Coefficient Thermistor) 144 may be further included.

  The gasket 150 is positioned between the can 130 and the cap assembly 140 to seal the can 130, and has a predetermined thickness t1 located in a region in contact with the cap assembly 140. The coating layer 155 is formed. Here, the coating layer 155 may be formed only in a region in contact with the cap assembly 140, but the gasket 150 may be formed along an outer peripheral surface of the gasket 150 in order to easily form the coating layer 155. It is preferable to form so that it may surround.

FIG. 2 is a graph illustrating the sealing pressure between the cap assembly 140 and the gasket 150 according to the thickness t1 of the coating layer 155.
As shown in FIG. 2, the sealing pressure between the cap assembly 140 and the gasket 150 is about 17 kgf / cm ² when the thickness t1 of the coating layer 155 is less than 2 mm. It can be seen that when the thickness t1 is 2 mm or more, the thickness is improved to about 21 kgf / cm ² .

  Accordingly, when the coating layer 155 positioned between the cap assembly 140 and the gasket 150 has a thickness t1 of 2 mm or more, the sealing performance between the cap assembly 140 and the gasket 150 is maximized. Can do.

  Here, as shown in FIG. 2, when the thickness t1 of the coating layer 155 is 2 mm or more, even if the thickness t1 of the coating layer 155 further increases, the gap between the cap assembly 140 and the gasket 150 is increased. Since the sealing pressure is not improved and only the overall height of the secondary battery 100 is increased by the thickness t1 of the coating layer 155, the thickness t1 of the coating layer 155 is preferably 2 to 3 mm.

  In addition, the secondary battery 100 according to the first embodiment of the present invention is illustrated in FIG. 3A in order to minimize the increase in the overall height of the secondary battery 100 due to the thickness t1 of the coating layer 155. As described above, a groove 151a having a predetermined depth t3 is formed in the region of the gasket 150 in contact with the cap assembly 140, and the depth t3 of the groove 151a is a coating located in the region where the groove 151a is formed. The thickness t2 of the layer 155 should be 2 mm or more. If the depth t3 of the groove 151a is too deep, the sealing performance of the can 130 is deteriorated. Therefore, the depth t3 of the groove 151a is 2 to 3 mm. Preferably there is.

  Here, the groove 151 a is for minimizing an increase in the overall height of the secondary battery 100, and when the coating layer 155 is formed to surround the gasket 150, More preferably, the thickness t2 of the coating layer 155 located in the region in contact with the cap assembly 140 is formed thicker than the region not in contact with the cap assembly 140 due to the depth t3 of the groove 151a.

  As shown in FIG. 3B, the secondary battery 100 according to the first embodiment of the present invention is configured such that the depth of the groove 151b is the gasket 151 so as to prevent the groove 151a of the gasket 150 from collapsing in the crimping process. As shown in FIG. 3C, the groove 151c can be formed thinner as it goes from the outer peripheral surface to the inner side, or the depth of the groove 151c can be decreased from the center of the groove 151c toward the periphery.

  As a result, in the secondary battery according to the first embodiment of the present invention, the cap assembly and the gasket are formed using a gasket in which a coating layer having a thickness of 2 mm or more is formed in a region in contact with the cap assembly. The gas tightness between the cap assembly and the gasket is minimized from being leaked between the cap assembly and the gasket.

  The secondary battery according to the first embodiment of the present invention may be configured such that a groove having a predetermined depth is formed in the gasket in contact with the cap assembly, so that the overall height of the secondary battery is increased by the coating layer. Can be prevented, and the tightness between the cap assembly and the gasket can be maximized.

<Second Embodiment>
4A is an exploded perspective view showing a secondary battery according to the second embodiment of the present invention, and FIG. 4B is a cross-sectional view showing the secondary battery according to the second embodiment of the present invention.

  4A and 4B, the secondary battery 200 according to the second embodiment of the present invention includes an electrode assembly 110, an opening formed on one side, and the electrode assembly 110 and an electrolyte solution (see FIG. 4). (Not shown), a cap assembly 210 positioned inside the opening of the can 130, and a gasket 220 positioned between the can 130 and the cap assembly 210.

  Here, the electrode assembly 110 and the can 130 of the secondary battery 200 according to the second embodiment of the present invention are the same as the electrode assembly 110 and the can 130 of the secondary battery 100 according to the first embodiment of the present invention. Since it is the same structure, the description is abbreviate | omitted.

  The cap assembly 210 is coupled to the upper end opening of the can 130 and is connected to an external terminal. The cap assembly 210 is ruptured when an internal pressure exceeds a predetermined level due to a gas generated when an internal abnormality occurs. A safety vent 212 for discharging the gas to the outside, a cap down 213 connected to the positive electrode tap 114 of the electrode assembly, an insulating film 214 positioned between the safety vent 212 and the cap down 213, and a lower portion of the cap down 213 The subplate 215 located is included. Here, a PTC thermistor 216 is positioned between the cap-up 211 and the safety vent 212 in order to improve the safety and reliability of the secondary battery.

  The gasket 220 is located between the can 130 and the cap assembly 210 to seal the can 220 and has a predetermined thickness t4 located in a region in contact with the cap assembly 140. A coating layer 225 is included. Here, the coating layer 225 may be formed only in a region in contact with the cap assembly 210, but the gasket 220 may be formed along the outer peripheral surface of the gasket 220 so that the coating layer 225 is easily formed. It is preferable to form so that 220 may surround.

  FIG. 5 is a graph illustrating a thickness t4 of a single coating process according to the viscosity of the coating layer 225, and FIG. 6 illustrates a sealing pressure between the cap assembly 210 and the gasket 220 according to the viscosity of the coating layer 225. It is a graph.

  As shown in FIG. 5, it can be seen that the thickness t4 of the coating layer 225 formed in a single coating process increases as the viscosity of the coating layer 225 increases. When the viscosity of the coating layer 225 is 3000 CPS or more, it can be seen that the coating layer 225 having a thickness of 2 mm or more is formed in one coating process.

Further, as shown in FIG. 6, the sealing pressure between the cap assembly 210 and the gasket 220 is about 17 kgf / cm ² when the viscosity of the coating layer 225 is less than 3000 CPS. It can be seen that when the viscosity of 225 is 3000 CPS or more, the viscosity is improved to about 21 kgf / cm ² .

  Accordingly, when the coating layer 225 having a viscosity of 3000 CPS or more is formed between the cap assembly 210 and the gasket 220, the cap assembly 140 and the gasket 150 may be formed by a single coating process. Sealability can be maximized.

  Here, similarly to the first example 100 of the present invention, the secondary battery 200 according to the second embodiment of the present invention has a groove (see FIG. 5) in the gasket 220 that contacts the cap assembly 210. The gas leak caused by an internal abnormality is caused between the gasket 210 and the safety vent 212 of the cap assembly 210 rather than between the gasket 210 and the insulating film 214 of the cap assembly 210. The groove of the gasket 220 is preferably formed in a region in contact with the safety vent 212 of the cap assembly 210.

  As a result, in the secondary battery according to the second embodiment of the present invention, a coating layer having a viscosity of 3000 CPS or more is formed in the gasket region in contact with the cap assembly, and the coating is performed only once. The sealing property between the cap assembly and the gasket can be maximized, and gas generated due to an internal abnormality can be minimized from leaking between the cap assembly and the gasket.

  Here, the secondary battery according to the first embodiment of the present invention and the secondary battery according to the second embodiment have the same configuration except for the configuration of the cap assembly. The coating layer formed on the gasket of the secondary battery according to the embodiment has a viscosity of 3000 CPS or more, and the thickness of the coating layer formed on the gasket of the secondary battery according to the second embodiment of the present invention. This has the same effect as when the thickness is 2 mm or more.

DESCRIPTION OF SYMBOLS 100 Secondary battery 110 Electrode assembly 111 Positive electrode plate 112 Cathode plate 113 Separator 114 Positive electrode tap 115 Cathode tap 130 Can 140 Cap assembly 150 Gasket

Claims (18)

An electrode assembly including a positive electrode plate, a negative electrode plate and a separator located between the two electrode plates;
A can for accommodating the electrode assembly having an opening formed on one side;
A cap assembly located inside the can opening and electrically connected to the electrode assembly;
Located between the can and cap assembly, wherein the coating layer having the above 2mm thick in an area where the cap assembly is positioned is formed, Ru groove is formed in a region in contact with the cap assembly gasket When,
A secondary battery comprising: The secondary battery of claim 1, wherein the depth of the groove, characterized in that thinner toward the inward from the outer peripheral surface of the gasket. The secondary battery of claim 1, the depth of the groove, characterized in that thinner toward the periphery from the center of the groove. The secondary battery according to claim 1 , wherein the groove has a depth of 2 to 3 mm. The cap assembly includes a safety vent that is broken or deformed by internal pressure of the can,
Groove of the gasket, the secondary battery according to claim 1, characterized in that formed in the region in contact with said safety vent. The rechargeable battery of claim 5 , wherein the cap assembly includes a cap-up, a current interrupting device, and a safety vent, which are sequentially disposed in the direction of the electrode assembly. The rechargeable battery of claim 5 , wherein the cap assembly includes a cap-up, a safety vent, a cap town, and a sub plate that are sequentially disposed in the direction of the electrode assembly.   The secondary battery according to claim 1, wherein the coating layer surrounds the gasket along an outer peripheral surface of the gasket. The secondary battery according to claim 8 , wherein the coating layer has a thickness in a region in contact with the cap assembly larger than a thickness in a region not in contact with the cap assembly.   The secondary battery according to claim 1, wherein the coating layer has a thickness of 2 to 3 mm. An electrode assembly including a positive electrode plate, a negative electrode plate and a separator located between the two electrode plates;
A can for accommodating the electrode assembly having an opening formed on one side;
A cap assembly located inside the can opening and electrically connected to the electrode assembly;
Wherein located between the can and cap assembly, the coating layer is formed on the cap assembly and the region includes a gasket groove Ru is formed in a region in contact with the cap assembly,
The secondary battery according to claim 1, wherein the coating layer has a viscosity of 3000 CPS or more. The secondary battery according to claim 11 , wherein the depth of the groove becomes thinner as it goes inward from the outer peripheral surface of the gasket. The secondary battery according to claim 11 , wherein the depth of the groove becomes thinner from the center to the periphery of the groove. The cap assembly includes a safety vent that is broken or deformed by internal pressure of the can,
The secondary battery according to claim 11 , wherein the groove of the gasket is formed in a region in contact with the safety vent. The rechargeable battery of claim 14 , wherein the cap assembly includes a cap-up, a current interrupt device, and a safety vent that are sequentially disposed in the direction of the electrode assembly. The rechargeable battery of claim 14 , wherein the cap assembly includes a cap-up, a safety vent, a cap town, and a sub plate that are sequentially disposed in the direction of the electrode assembly. The secondary battery according to claim 11 , wherein the coating layer surrounds the gasket along an outer peripheral surface of the gasket. The secondary battery according to claim 11 , wherein a thickness of the coating layer is 2 mm or more.

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