KR101272178B1 - Secondary battery and method for manufacturing the same - Google Patents

Abstract

A secondary battery according to the present invention includes a metallic can including an accommodating part and an open part accommodating an electrode assembly and an electrolyte solution; A metallic cap positioned in the opening of the can to seal the can; And a fusion bonding member having a melting point lower than a melting point of the can and the cap and joining the can and the cap in a state interposed between the can and the cap. The can and the cap are joined in the molten state.

Description

Secondary battery and its manufacturing method {SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery and a method of manufacturing the same, and more particularly, to a secondary battery for joining a can and a cap by using a melt bonding member having a melting point lower than the melting point of the can and cap forming a case of the secondary battery. It relates to a manufacturing method.

In general, many studies have been conducted on batteries used as a power source for electronic products by making the structure of portable electronic products such as digital cameras, camcorders, portable telephones, and portable PCs lighter or more functional. Such a battery can be used continuously by charging / discharging.

Typically, batteries that can be repeatedly charged / discharged, that is, secondary batteries are classified into nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, lithium secondary batteries, and the like. Among them, lithium secondary batteries are generally used in consideration of their lifetime and capacity. It is becoming.

The lithium secondary battery is classified into a lithium metal battery using a liquid electrolyte, a lithium ion battery, and a lithium polymer battery using a polymer solid electrolyte according to the type of electrolyte. Lithium polymer batteries are classified into fully solid lithium polymer batteries containing no organic electrolyte at all and lithium ion polymer batteries using a gel polymer electrolyte containing organic electrolyte according to the type of polymer solid electrolyte.

Lithium ion secondary batteries have improved energy density and repeated service life characteristics compared to conventional secondary battery products, and these advantages have steadily increased demand and usage range. However, the lithium ion secondary battery maintains a more stable performance against the change and risk factors of the external environment due to the high energy density, and in the abnormal situation, the contents of the electrode leak out of the case (pack) to violate the safety. To prevent this from happening, it is necessary to introduce fundamental safety measures in the product design.

Metallic sheaths (eg, cases or packs) surrounding the electrode assembly have been used for a long time as one way to meet this need, and their shapes and sizes vary. Regardless of its form, however, the existing metal exterior material is generally composed of a can (container) for accommodating the contents of the battery and a cap (cover) for covering the material. These alloys are used.

In general, in order to bond cans and caps or seal their contacts as battery cells, for example, physical fixing such as pressing or crimping, fixing by thermal processing such as welding, or the like has been used. In particular, the welding method ensures stable sealing of the battery since the base material (can and cap) is melted and mixed at the joint and then solidified to form a permanent bond at the joint. For example, laser welding, arc welding, plasma welding, etc. have been used for welding the metal sheath, and related arts may refer to various patents filed by the present applicant (Patent Application No. 2000-0021513). ; Patent Application No. 2000-0014318; Patent Application No. 2000-0044179; Patent Application No. 2003-0065237)

The metal sheath, which is permanently bonded and / or sealed by welding, not only provides the reliability of long-term use of the battery, but also protects the contents of the battery from external environmental factors such as pressure and mechanical shock, temperature and humidity changes, and at the same time It effectively prevents harmful chemicals from leaking out.

However, the conventional sealing method of welding a can and a cap of a battery by a method such as welding by applying a metal exterior material has the following problems.

First, high heat generation is required because the base material (exterior material) must be melted directly (melting temperature of iron and stainless steel is 1500 ℃, aluminum melting temperature is 660 ℃ or more).

Second, since high heat is applied directly to the packaging during the sealing process, it may cause fatal damage to the components of the battery (eg, separator, electrolyte, etc.) that are weak to heat.

Third, the welding conditions are difficult to optimize, and the time and cost for welding are high.

Fourth, there is a fear that fine defects such as, for example, pin holes may occur in the welded portion due to deformation and / or modification of the base material generated during the welding process.

Fifth, it is difficult to control the joint (or welding) area, which limits the welding strength. In particular, in the case of a thin optical area battery having high capacity / high power characteristics, a large time and a cost for welding are greatly increased as the bonding distance and the bonding area become large.

On the other hand, contrary to the demand for a stable sealing of the battery, if the pressure and temperature inside the battery increase due to battery misuse or abuse, or other causes, the sealing state of the battery collapses as soon as possible, so that It is necessary to stabilize the pressure at room temperature and normal pressure. Because of this, most secondary batteries (especially in the case of secondary batteries using metal cladding) have a separate pressure relief mechanism such as vent, for example, and this pressure relief mechanism is used in battery abnormalities. By physically connecting the inside and the outside, the battery can be stabilized.

However, conventional batteries using a metal exterior material have to have a pressure releasing mechanism having a different design according to each battery model, size, capacity, type of use, etc., thereby increasing battery manufacturing cost and process cost and cost of the product. There was a problem that increases.

The present invention has been conceived to improve the problems of the prior art as described above, by bonding using a dissimilar metal melt at a temperature lower than the melting point of the base material (eg, freely selectable from around 140 ° C), It is possible to minimize the heat transferred to the inside, can be easily and quickly sealed without constraints of the shape of the bonding site, there is no deformation of the base material, control the bonding area by controlling the coating amount of dissimilar metal melt material of the battery Provided is a secondary battery having improved sealing structure of a metal packaging material and a method of manufacturing the same.

By improving the requirements for the design of a separate vent mechanism, which has been another problem of the prior art as described above, the vent mechanism can release the sealability of the cell at a specific temperature by selecting the material of the appropriate dissimilar metal melt. Provided are a secondary battery integrated with a sealing and / or a joint of a battery and a method of manufacturing the same. This object is focused on the ease of controlling the coating amount and the bonding area of the molten material, it is possible to implement a secondary battery having a vent integrated sealing design capable of pressure durability control.

A secondary battery according to the present invention for achieving the above object is a metallic can including an accommodating portion and an opening for accommodating the electrode assembly and the electrolyte; A metallic cap positioned in the opening of the can to seal the can; And a fusion bonding member having a melting point lower than a melting point of the can and the cap and joining the can and the cap in a state interposed between the can and the cap. The can and the cap can be joined in a molten state.

The fusion bonding member may be melted by any one of contact resistance, high frequency heating, laser, light beam, pulse heat, or hot-ram.

The laser uses a YAG laser and can be absorbed by the fusion bonding member, and the light beam can be obtained by using a xenon lamp or a halogen lamp with high brightness.

In addition, the secondary battery according to the present invention includes a metallic can including an accommodating part and an open part accommodating the electrode assembly and the electrolyte solution; A metallic cap positioned in the opening of the can to seal the can; And a fusion bonding member having a melting point lower than a melting point of the can and the cap and joining the can and the cap in a state interposed between the can and the cap. 10. May be melted at 120 ° C.

The fusion bonding member may include at least one of gallium (Ga), indium (In), cadmium (Cd), or bismuth (Bi).

The molten bonding member is melted by a reflow apparatus including a heating furnace and a conveyor transported in the heating furnace, wherein the molten bonding member is applied by the conveyor in a state where it is applied to the junction of the can and the cap. It can be fed into the furnace and melted.

The melt bonding member may be melted by hot air or infrared rays heating the inside of the heating furnace.

The melt bonding member may be melted when the temperature of the accommodating part surrounded by the can and the cap rises to release the sealed state of the can and the cap.

On the other hand, according to another field of the invention, the present invention comprises the steps of providing a metallic can including a receiving portion and an opening that is accommodated together with the electrode assembly and the electrolyte; Providing a metallic cap positioned at the opening of the can to seal the can; Providing a fusion bonding member having a melting point lower than a melting point of the can and the cap and between a junction of the can and the cap; And heating and melting the melt bonding member, and bonding the can and the cap to each other, wherein the bonding of the can and the cap comprises locally heating the reflow bonding member or reflowing the cap. Provided is a method for manufacturing a secondary battery, wherein the melt bonding member is heated.

Local heating of the molten bonding member may be performed using any one of contact resistance, high frequency heating, laser, light beam, pulse heat, or hot-ram. Can be heated locally.

The laser uses a YAG laser absorbed by the fusion bonding member, and the light beam can be obtained by using a xenon lamp or a halogen lamp with high brightness.

The reflow method may be applied when the melt bonding member is melted at 10 ° C. to 120 ° C.

The fusion bonding member may include at least one of gallium (Ga), indium (In), cadmium (Cd), or bismuth (Bi).

The molten bonding member may be melted by convection hot air, infrared rays, or heat of condensation.

A cooling jig may be used to prevent heat generated by hot air, infrared rays, or condensation heat that melts the fusion bonding member from being transferred to the battery element accommodated in the accommodating part.

In the secondary battery according to the present invention, in the process of melting and attaching different kinds of metals or metal compounds having a melting temperature range of a predetermined range to a base material (stainless steel, aluminum, iron, etc.) to be joined when sealing a metal exterior material. By using a method of applying a metal / metal compound having a lower melting point than that of the base material to the bonding surface or around the junction of the exterior material and maintaining the sealing of the battery by the dissimilar metal / metal compound thus applied, the following effects are obtained.

First, various products can be sealed without being limited by the shape of the joint and the product.

Second, since the bonding is performed at a lower temperature than the welding method, which is commonly used in the related art, it is possible to prevent the risk of thermal damage to the base metal or the components of the battery.

Third, since there are various types and melting points of dissimilar metals / metal compounds used as molten materials and commercialized, there is a wide choice of materials.

Fourth, since the melting point of the junction is freely controlled, a temperature-sensitive vent mechanism that is relatively precisely controlled in a specific temperature range may be integrally implemented at the junction.

Fifth, by adjusting the application area (bonding area) of the molten material, the joint itself can also be utilized as a pressure-sensitive vent mechanism that is controlled in a specific pressure range.

The field to which the secondary battery of the present invention can be particularly effectively applied is a thin light area secondary battery product, which has the effect of supplementing and improving the weak points of the prior art.

In addition, since the present invention uses a local heating method to heat the molten bonding member, it is possible to reduce the possibility of being affected by heat in the battery components.

In addition, the present invention can increase the productivity of the secondary battery, because the melt bonding member can be melted by a reflow method using a conveyor system in the case of using a melt bonding member having a low melting point, the melt bonding portion at a lower temperature Since the ash can be melted, the onset temperature of the vent function can be lowered, thereby further increasing the safety of the secondary battery.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further augment the technical spirit of the invention. And should not be construed as limiting.
1 is an exploded perspective view schematically illustrating a configuration of a rechargeable battery according to an exemplary embodiment of the present invention.
FIG. 2 is a plan view schematically illustrating the cap of FIG. 1. FIG.
3 is a view illustrating matters to be considered when selecting a temperature / pressure range of a melt bonding member according to preferred embodiments of the present invention.
4 is a perspective view schematically showing an example of a melt bonding member 30 according to a preferred embodiment of the present invention.
5A and 5B are schematic diagrams each illustrating a process of sealing a rechargeable battery according to an exemplary embodiment of the present invention.
6A and 6B are cross-sectional views schematically illustrating a rechargeable battery according to another exemplary embodiment of the present invention.
7 is a cross-sectional view illustrating a modification of the receiving groove formed on the surface of the can and the cap according to a preferred embodiment of the present invention.
8 is a perspective view schematically illustrating a sealing assembly process of a rechargeable battery according to another exemplary embodiment of the present invention.
9 is a perspective view schematically illustrating a bonding process of a secondary battery according to still another embodiment of the present invention.

Hereinafter, a secondary battery according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the figures, like elements have been given the same reference numerals.

1 is an exploded perspective view schematically illustrating a configuration of a rechargeable battery according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the rechargeable battery 100 includes a metallic can 10, a metallic cap 20, and a fusion bonding member 30 interposed between the can 10 and the cap 20. .

The can 10 has an accommodating portion 12 for accommodating components of a battery including an electrode assembly 40 and an electrolyte (not shown), and has an open portion 14 open at one end thereof. The can 10 may itself function as an electrode terminal. Although the can 10 in this embodiment is shown as a tetrahedral shaped battery, it will be readily understood by those skilled in the art that the can 10 can be modified to any number of dimensions required by the industry, such as a cylindrical battery or any other type of battery. The receiving portion 12 of the can 10 is schematically illustrated in a rectangular shape as a space for accommodating / receiving the electrode assembly 40 and the electrolyte solution, but the shape or shape of the electrode assembly 40 actually assembled. It may be changed in a corresponding form. The opening 14 of the can 10 is covered by the cap 20 and is not particularly limited in shape and size.

The can 10 has a substantially flat joining plane 18 in the form of a flange projecting by a predetermined length in an outward direction substantially perpendicular to the side wall 16. This flange-shaped joining plane 18 is to ensure a stable joining area with respect to the thickness of the can 10.

According to an exemplary embodiment of the present invention, the can 10 and / or the cap 20 may be configured such that the contents such as the electrode assembly 40 and the electrolyte, which are accommodated in the accommodating part 12, do not leak outside or inflow of outside air. And a material that ensures airtightness to the extent that the contents can operate normally against the pressure difference, physical, chemical, and climatic environmental impact between the inside and the outside. For example, can 10 and / or cap 20 has a thermal conductivity of at least about 10 kcal / mh ° C. (20 ° C.), a tensile strength of at least about 5 kgf / mm ² , and a thickness of at least about 30 μm.

The electrode assembly 40 has a structure in which a cathode plate / separator / cathode plate is sequentially disposed (for example, a lamination type in which a plurality of unit electrodes are stacked or a jelly-roll type in which unit electrodes are wound), and the overall shape is a cuboid or coin type. It may be modified in various ways.

Typically, in the secondary battery, the positive electrode plate has a structure in which a positive electrode active material containing lithium-based oxide as a main component is applied to at least one side of the positive electrode current collector of an aluminum thin plate, and the negative electrode plate has at least one side of the negative electrode current collector of a copper thin plate. It is a structure to which the negative electrode active material which has a carbon material as a main component was apply | coated to the. The positive electrode plate and the negative electrode plate each have a positive electrode tab and a negative electrode tab. The positive electrode tab and the negative electrode tab may be disposed at different positions according to polarity, and the positive electrode tab and the negative electrode tab portion protruding from the positive electrode plate and the negative electrode plate may be attached with an insulating tape to prevent a short circuit between the electrode plates. In addition, the separator uses a porous polymer film for separating the positive electrode plate and the negative electrode plate. The structure of the electrode assembly 40 composed of the positive plate / separator / cathode plate can be modified by any person skilled in the art.

FIG. 2 is a plan view schematically illustrating the cap of FIG. 1. FIG.

1 and 2, the cap 20 covers and seals the opening 14 of the can 10, and the cap 20 overlaps the joining plane 18 of the can 10. 22). The cap 20 has a plate shape as a whole, and may have a through hole (not shown) through which an electrode terminal (not shown) of the electrode assembly 40 may penetrate. An insulation material, a terminal plate (not shown) may be included. In addition, the cap 20 may be provided with an electrolyte injection hole (not shown) for injecting electrolyte into the can 10 in a sealed state.

In addition, the can 10 and / or the cap 20 is preferably plated with nickel or copper in order to improve the bonding property with the fusion bonding member 30.

The melt bonding member 30 has a melting point lower than the melting point of the metallic can 10 and the cap 20, and the second bonding plane 22 of the bonding plane 18 and the cap 20 of the can 10. Is located between the junctions,

The melt bonding member 30 has a melting point that is lower than the melting point of the base material, and has a melting point without fear of internal heat transfer, and thus can be expected to have sufficient bonding strength due to its excellent bonding property with the base material. Affinity) and may be selected from various kinds of metals and metal compounds in consideration of the property of melting and releasing the sealing property when reaching a specific temperature. On the other hand, the reason for using the alloy as the fusion bonding member 30, can lower the melting point than the single metal, improve the mechanical strength, lower the price, can be expected to bond affinity with the base metal That is, it can have various liquidus-solidus temperature ranges. Available types and features of the fusion bonding member 30 are as shown in Table 1 below (type 1 of the fusion bonding member).

line Kinds Melting point

Sn-Pb system

Sn-37Pb 183 ℃ Sn-40Pb 190 ℃ Sn-45Pb 203 ℃ Sn-50Pb 215 ° C Sn-55Pb 227 ℃

Sn-Cu system

Sn-9.5Cu 227 ~ 422 ℃ Sn-3Cu 227 ~ 312 ℃ Sn-0.7Cu 227 ℃ Sn-0.7Cu-0.3Ag 221 ~ 227 ℃ Sn-0.5Cu-0.06Ni 220 ~ 233 ℃ Sn-Zn system
Sn-9Zn 197 ~ 198 ℃ Sn-8Zn-3Bi 190 ~ 197 ℃
Sn-Ag system

Sn-3.5Ag 221 ℃ Sn-3.0Ag-0.2Cu 217 ~ 220 ℃ Sn-1Ag-4Cu 217 ~ 225 ℃ Sn-4Ag-0.1Ni 221 ~ 231 ℃
Etc

Sn-49In 117 ℃ Sn-8In-3.5Ag-0.5Bi 170 ~ 206 ℃ Sn-57Bi-1Ag 138 ~ 140 ℃ Zn-5Al 382 ℃

Meanwhile, in the preferred embodiments of the present invention, the fusion bonding member 30 is described as including lead, but it is apparent to those skilled in the art that lead or alloy thereof may not be selected in consideration of environmentally friendly factors.

According to one preferred embodiment of the present invention, the melt bonding member 30 has a melting point between about 100 ° C and about 450 ° C, more preferably between about 138 ° C and about 250 ° C.

According to a preferred embodiment of the present invention, the melt bonding member 30 selects, for example, Sn-8Zn-3Bi having a melting point of 190 ° C. This is because in the conventional method of welding by plasma welding, a high heat of 1000 ° C. or more is applied directly to the exterior material, a lot of energy / time is required to achieve the process conditions, the electrolyte is separated at 100 ° C., and the separator is formed at 120 to 140 ° C. This is because major components of the secondary battery 100 may be thermally damaged during the welding process, such as blocking pores and breaking the separator at 150 to 180 ° C.

Therefore, in consideration of the damage of the components of the secondary battery 100, the fusion bonding member 30 has a low temperature capable of melting, preferably avoiding the high heat source is disposed in the process, and the general purpose equipment (e.g. For example, it is preferable to use a heater, a jig). In addition, the melt bonding member 30 is not released or weakened in the general operating range (eg, less than 80 ℃) of the secondary battery 100, the generalized heat-resistant harsh test standard (UL standard for lithium ion battery) 130 ℃), which maintains hermetic seal so as not to cause leakage unless the internal pressure is rapidly increased (in the range where the insulation of the separator is not broken so that an internal short circuit does not occur), but it is known to pose a fatal danger to the safety of the battery. It is desirable that the sealability be sufficiently released before reaching the internal thermal runaway onset temperature (eg, about 200 ° C.) of the positive electrode material. For this reason, in the general vent mechanism of the conventional secondary battery (bent means are provided in some narrow area of the exterior material), even if the vent mechanism is operated, the discharge through a sufficient area compared to the ejection pattern of the internal material is prevented. It is difficult, and moreover, the vent hole is clogged by the ejecting material. However, according to the vent mechanism combined melt bonding member 30 of the present embodiment, the intended wide area can be utilized as the vent mechanism, and the temperature and the endurance pressure can be easily adjusted within such a range.

The temperature / pressure range selection of the fusion bonding member 30 according to embodiments of the present invention may refer to FIG. 3. Those skilled in the art will understand that the temperature and pressure of FIG. 3 are merely exemplary, and that the optimum values can be varied in various ways depending on the product design.

On the other hand, the melt bonding member 30 according to the embodiments of the present invention may be melted by local heating. By locally heating the melt bonding member 30 as described above, it is possible to reduce the possibility of major components of the secondary battery 100 being damaged by heat for heating the melt bonding member 30.

Here, a method of locally heating the molten bonding member 30 may include contact resistance, high frequency sealing, laser, light beam, pulse heat, or hot-ram. Either way can be used.

First, the contact resistance method uses the same principle as that of resistance welding, and is melted by heat generated by contact resistance between at least one of the can 10 or the cap 20 and the fusion bonding member 30. The bonding member 30 is melted. At this time, it is preferable that the can 10 and the cap 20 are pressurized from both sides in the molten state toward the melt bonding member 30 in the molten state.

For heat generation by the contact resistance, the fusion bonding member 30 may be melted by a resistance seam welder (not shown) having a welding electrode in contact with the surface of the can 10 and the cap 20. Since the resistance seam welder is the same as or similar to that used for general resistance seam welding, a detailed description thereof will be omitted.

When the melt bonding member 30 is melted by the contact resistance, the melt bonding member 30 may have a resistance of the can 10 and the cap 20, a welding electrode contacting the can 10 and the cap 20 (not shown). C) and the contact resistance between the can 10 and the cap 20 and the heat generated by the resistance between the melt bonding member 30 and at least one of the can 10 or the cap 20. . At this time, the resistance between at least one of the can 10 or the cap 20 and the melt bonding member 30 is preferably larger than the remaining resistance.

In addition, the contact resistance between the welding electrode contacting the can 10 and the cap 20 and the can 10 and the cap 20 can be controlled according to the material, shape or size of the welding electrode. The molten state of the fusion bonding member 30 may be controlled by controlling the magnitude or duration of the welding current supplied to the welding electrode or the pressure applied by the welding electrode to the can 10 and the cap 20. Here, the welding electrode may have a disk shape, and may press the can 10 and the cap 20 continuously while rotating while being in contact with the can 10 and the cap 20.

The method of locally heating the fusion bonding member 30 by high frequency sealing uses a high frequency sealer or a high frequency sealer, and uses high frequency induction heating. When the permanent magnet in the center of the coil shape is inserted and removed, the magnetic field is changed and an electromagnetic induction phenomenon occurs in which the current flows in the conductor.In the high frequency induction heating, an alternating magnetic flux is generated by flowing an alternating current through the coil instead of the permanent magnet. Induced current (eddy current) flows to the object to be heated, and this induced current generates joule heat by the eddy current loss and heats the object to be heated by the generated heat. The method using high frequency heating or high frequency sealer has a very short heating time, uniformly manages heating temperature, heating time and heating output, and can effectively prevent overheating.

The method using a laser is a method of heating the fusion bonding member 30 in a non-contact manner, and it is preferable to use a YAG laser. YAG laser is advantageous in the automation of equipment because the wavelength is as short as 1.06㎛ and can be absorbed well in the molten bonding member 30, and can be transmitted in the quartz fiber (fiber). The method using the light beam is also non-contact, and a light source may use a xenon lamp or a halogen lamp with high brightness.

Pulse heat (pulse heat) is a contact heating method, it can be said that the application of resistance welding. Pulse heating is to press the contact of the tip (heater material) of various shapes to the junction of the can 10 and the cap 20, and to flow the current through the tip for a short time and to utilize the joule heat of the tip generated at that time Can be heated. Since the tip contacted by the pulse heating generates heat only during the current flow time, the melting and cooling of the molten bonding member 30 can be performed at almost the same time, and thus the influence of the heat of the main components of the battery is reduced. It can be said little. Here, the material of the tip is high resistance, excellent workability, molybdenum (Mo) or tungsten (W) that does not melt in the molten bonding member 30 may be used.

The hot-ram method is also a contact heating method, which is a method of contact press soldering from a ram that is always heated by a sheath heater to maintain a high temperature. This method can be used when joining pre-soldered parts and is suitable for simultaneous heating of multiple conductors of wide width, such as flexible substrates, because they can heat temperatures uniformly over a wide range. . Accordingly, the hot ram method may be applied even when the can 10 and the cap 20 formed of a conductor having a thin thickness and a large area are heated at the same time.

Meanwhile, the melting bonding member 30 illustrated in Table 1 has a melting point of about 100 ° C. to about 450 ° C., but is largely different from a general operating temperature range (less than 80 ° C.) of the secondary battery 100. There is also some difference from the thermal runaway onset temperature (200 ° C) of the positive electrode material. Therefore, the present invention may use a melt bonding member 30 having a lower melting point and having a different composition in addition to the melt bonding member 30 having the composition shown in Table 1 above.

For example, the melt bonding member 30 of the present invention may be melted at 10 ° C to 120 ° C. If the melt bonding member 30 is melted at 10 ° C. to 120 ° C., the melt bonding member 30 may be formed even before the thermal runaway temperature of the positive electrode material is reached or even if the temperature is slightly higher than the general operating temperature range of the secondary battery 100. 30) may be melted. However, even in the case of having such a melting point, it is preferable to exclude the melt bonding member 30 having a melting point lower than the general operating temperature range of the secondary battery 100.

The molten bonding member 30 having a low melting point is formed of gallium (Ga), indium (In), cadmium (Cd), or bismuth (Bi), as illustrated in Table 2 below (Type 2 of the melting bonding member). It may include at least one.

Kinds Melting point 61Ga-25In-13Sn-Zn 7 ℃ 66.5Ga-20.5In-13Sn 11 ℃ 42.9Bi-21.7Pb-18.3In-8Sn-5.1Cd 38 ℃ 44.7Bi-22.6Pb-16.1In-11.3Sn-5.3Cd 47 C 49Bi-21In-18Pb-12Sn 58 ℃ 61.7In-30.8Bi-7.5Cd 62 ℃ 50Bi-26.7Pb-13.3Sn-10Cd 70 ℃ 48.5Bi-41.5In-10Cd 78 ℃ 54Bi-29.7In-16.3Sn 81 ℃ 51.1Bi-39.8Pb-8.1Cd-1In 87 ℃ 51.6Bi-40.2Pb-8.2Cd 92 ° C 50Bi-28Pb-22Sn 100 ℃ 53.7Bi-43.1Pb-3.2Sn 108 ° C 55Bi-44Pb-1In 120 DEG C

As such, in the case of using the melt bonding member 30 having a melting point of a relatively low temperature, the melt bonding member 30 is used by using a reflow method used for surface mounting technology (SMT). Can dissolve.

In the reflow method, the can 10 and the cap 20 may be bonded using a reflow apparatus (not shown) including a heating furnace and a conveyor transferred in the heating furnace. The fusion bonding member 30 may be supplied into the heating furnace by the conveyor and melted while being applied to the bonding portion of the can 10 and the cap 20.

The melt bonding member 30 applied to the can 10 and the cap 20 may be melted and solidified while undergoing preheating, main heating (reflow heating), and cooling while passing through a heating furnace. In order to melt the molten bonding member 30 by the reflow method, it is important to control the temperature distribution inside the furnace and the speed of the conveyor, and match the heat capacity of the can 10, the cap 20, and the molten bonding member 30. It is necessary to create and maintain an appropriate temperature profile.

On the other hand, in order to heat the molten bonding member 30 having a low melting point in the furnace by the reflow method, hot air or infrared rays may be supplied into the furnace.

First, the hot air method may supply the hot air to heat the molten bonding member 30 by convection the hot air inside the heating furnace. Without sufficient convection, the heating rate can be lowered and the heating time can be relatively long. In order to increase the heating rate, it is desirable to use forced convection and optimized gas flow together. When the hot air is supplied, temperature uniformity of the surface of the can 10 and the cap 20 may be changed by the flow of hot air. Therefore, it is necessary to appropriately control the position of the heater that heats the air and the circulation method of the hot air so that the surfaces of the can 10 and the cap 20 are uniformly heated.

In the case of supplying infrared rays, infrared rays operating at wavelengths of 1 μm or less to 6 μm may be radiated into a heating furnace. Compared with a hot air system, heating by infrared rays may cause overheating.

In addition, it is also possible to melt the melting bonding member 30 having a low melting point using the heat of condensation. When the can 10 and the cap 20 having low temperature are brought into contact with the vapor vaporized by heating a liquid having a large heat transfer coefficient with the heater, the heat of condensation may be generated. It is also possible to heat the fusion bonding member 30 applied to the bonding portion of the. When the molten bonding member 30 is heated by the heat of condensation, there is an advantage in that thermal damage of the main battery components of the secondary electrode 100 may be prevented.

As described above, the secondary battery 100 according to the present invention comprises the steps of providing a metallic can 10 including an accommodating part and an opening part in which an electrode assembly and an electrolyte are accommodated together, and the can 10 can be sealed. Providing a metallic cap 20 located in the opening of the 10, having a melting point lower than the melting point of the can 10 and the cap 20 and melting between the can 10 and the junction of the cap 20 It can be prepared by the method of manufacturing a secondary battery 100 comprising the step of providing a bonding member 30 and the melting and melting of the bonding member 30 and bonding the can 10 and the cap 20. have.

Here, the step of bonding the can 10 and the cap 20 may be performed by locally heating the melt bonding member 30 or by heating the melt bonding member 30 by a reflow method.

Local heating of the molten bonding member 30 may use any one of contact resistance, high frequency sealing, laser, light beam, pulse heat or hot-ram. The molten bonding member 30 can be locally heated. By locally heating the molten bonding member 30 in this manner, it is possible to reduce the possibility of major components of the battery being adversely affected by heat.

Here, a YAG laser absorbed by the fusion bonding member 30 may be used for heating using a laser, and a xenon lamp or halogen lamp having a high brightness may be obtained when heating with a light beam. have.

In addition, when the melt bonding member 30 is melted at 10 ° C to 120 ° C, the melt bonding member 30 may be melted by applying a reflow method. In this case, the fusion bonding member 30 may include at least one of gallium (Ga), indium (In), cadmium (Cd) or bismuth (Bi).

When the molten bonding member 30 having a low melting point is heated by using a reflow method, the molten bonding member 30 may be melted using convection hot air, infrared rays, or condensation heat. At this time, a cooling jig may be used to prevent heat generated by hot air, infrared rays or condensation heat that melts the fusion bonding member 30 from being transmitted to the main battery elements of the battery.

Meanwhile, the bonding or sealing state between the can 10 and the cap 20 is controlled according to the melting point of the fusion bonding member 30. In addition, the bonding or sealing state between the can 10 and the cap 20 can be controlled by the melting point of the fusion bonding member. In addition, the sealing or bonding strength between the can 10 and the cap 20 may be adjusted by the area of the fusion bonding member 30 interposed between the can 10 and the cap 20.

4 is a perspective view schematically showing an example of a melt bonding member 30 according to a preferred embodiment of the present invention.

1 and 4, the fusion bonding member 30 according to the present embodiment is in contact with the bonding plane 18 of the can 10 and the second bonding plane 22 of the cap 20 to be melted. The cross section is pre-formed into an annular shape that is rectangular in shape and forms a substantially rectangular closed loop for post solidification. Those skilled in the art will appreciate that such molding methods can be implemented in a variety of ways already known in the art. The molten bonding member 30 is formed into a solid phase, including a method as described above, by direct heating by a hot wire heater (not shown), ultrasonic heating by high frequency, heating by resistance heat, and by a jig (not shown). The joint between the can 10 and the cap 20 is sealed while being pressed and melted by the applied pressure.

5A and 5B are schematic diagrams each schematically illustrating a process of sealing a rechargeable battery according to an exemplary embodiment of the present invention.

As shown in FIG. 5A, the can 10 containing the electrode assembly 40 is inserted into the opening of the lower jig 52 so that the end of the lower jig 52 supports the flange of the can 10. The melt bonding member 30 is positioned on the bonding plane 18 of the can 10 and the cap 20 is folded thereon to press the upper jig 54 at the top of the cap 20 to pressurize to a predetermined pressure and temperature. 5B, the cap 20 is firmly fixed to the can 10 while the melt bonding member 30 is solidified after melting.

6A and 6B are cross-sectional views schematically illustrating a rechargeable battery according to another exemplary embodiment of the present invention.

6A and 6B, the secondary battery 200 according to the present embodiment is preformed in at least one of the bonding plane 118 of the can 110 and the second bonding plane 122 of the cap 120. The receiving grooves 119 and 123 are provided to accommodate the molten bonding member 30. That is, according to the present embodiment, by placing the can 110 and the cap 120 so that the fusion splicing member 30 can be inserted into the receiving grooves 119 and 123 to be considered by the jig as described above or by those skilled in the art. Pressing the can 110 and the cap 120 to a predetermined pressure and temperature using other devices may be used to melt the fusion bonding member 30 to melt in the bonding plane 118 and the second bonding plane 122. When the bonding member 30 is melted and solidified, the can 110 and the cap 120 are tightly sealed or bonded.

In addition, the secondary battery 200 according to the present exemplary embodiment may be a molten bonding member 30 previously formed in at least one of the bonding plane 118 of the can 110 and the second bonding plane 122 of the cap 120. Flow facilitation (not shown) may be formed to allow even flow between the junction of the can 10 and the cap 20 in the molten state. The flow promoting part may have a concave-convex or embossing form formed on at least one side of the junction of the can 10 or the cap 20. Here, the flow promoting portion may be formed to have a large surface roughness compared to its surroundings.

The receiving grooves 119 and 123 of FIGS. 6A and 6B are shown drawn in the joining surfaces 118 and 122 of the can 110 and the cap 120 at right angles, as shown in FIG. Likewise, the groove 210 and the recess 220 may be deformed to one of ordinary skill in the art such as a recessed groove 223 formed in a recess on at least one surface of the joining surfaces of the can 210 and the cap 220. According to the present embodiment, the melt bonding member 230 may be pre-molded in a circular cross section.

8 is a perspective view schematically illustrating a sealing assembly process of a rechargeable battery according to another exemplary embodiment of the present invention.

Referring to FIG. 8, in the rechargeable battery 300 according to the present exemplary embodiment, the can 310 includes an extension part 311 extending substantially vertically from the bonding plane 318, and the cap 320 may be formed. It is formed stepped from the edge of the cap plate 321 and is in contact with the bonding plane 318 of the can 310 and its end is in contact with the side wall of the extension 319 to form a predetermined space to melt the liquid in the space. It is provided with a step 323 that can accommodate the bonding member 330.

According to the present exemplary embodiment, the cap 320 is positioned in the state in which the electrode assembly 40 is accommodated inside the can 310, and then in the space formed by the extension 319 and the step 323, the molten state ( When the melt bonding member 330 of the liquid phase is poured and the melt bonding member 330 is solidified, the can 310 and the cap 320 may be sealed and bonded. According to the present embodiment, a gas cat (not shown) may be interposed at a portion where the can 310 and the cap 320 contact each other.

9 is a perspective view schematically illustrating a bonding process of a secondary battery according to still another embodiment of the present invention.

Referring to FIG. 9, the secondary battery according to the present embodiment uses the can 10 and the cap 20 illustrated in FIGS. 1 and 2, and uses the can 10 using a solder paste printer 401 known in the art. The can 10 and the cap 20 by printing the molten bonding member 430 in a paste state on the bonding surface 18 of the paste 10 and then heating and pressurizing it to a predetermined temperature and a predetermined pressure with the cap 20 placed thereon. ) Can be melt bonded.

As mentioned above, the secondary battery according to the preferred embodiments of the present invention is particularly useful when applied to a thin wide-area square battery (when the start-end distance of the junction is long or the area is large), but on the other hand For example, those skilled in the art will understand that a variety of batteries, such as secondary batteries such as cylindrical batteries, coin-type batteries, nickel-cadmium batteries, and nickel hydrogen batteries, and the like may be applied to various types of packaging materials or bonding structures or shapes thereof. .

Various embodiments of the invention have been described above. However, those skilled in the art will appreciate that the foregoing descriptions of the preferred embodiments are merely exemplary, and that the present invention is capable of modifications and variations to the above described devices and methods. Those skilled in the art will recognize or ascertain many equivalents to the specific embodiments disclosed herein by routine experimentation. Such modifications, variations and equivalents are intended to be included within the spirit and scope of the invention as set forth in the claims below.

100: secondary battery 10: can
20: cap 30: melt bonding member
40: electrode assembly

Claims (16)

A metallic can including an accommodating part and an open part accommodating the electrode assembly and the electrolyte;
A metallic cap positioned in the opening of the can to seal the can; And
And a melting joint member having a melting point lower than the melting point of the can and the cap and joining the can and the cap in a state interposed between the can and the cap.
At least one of the joining plane of the can and the joining plane of the cap has a concave-convex or embossed shape or a larger surface to allow the molten joining member to flow evenly between the joining portion of the can and the cap in a molten state. A flow promoting part having a roughness is formed,
The melt bonding member is a secondary battery, characterized in that for bonding the can and the cap in a molten state by local heating.
The method of claim 1,
The molten junction member is melted by any one of contact resistance, high frequency heating, laser, light beam, pulse heat or hot-ram.
The method of claim 2,
The laser uses a YAG laser, characterized in that the secondary battery is absorbed by the molten bonding member.
The method of claim 2,
The light beam is obtained by using a xenon lamp or a halogen lamp with high luminance.
A metallic can including an accommodating part and an open part accommodating the electrode assembly and the electrolyte;
A metallic cap positioned in the opening of the can to seal the can; And
And a melting joint member having a melting point lower than the melting point of the can and the cap and joining the can and the cap in a state interposed between the can and the cap.
At least one of the joining plane of the can and the joining plane of the cap has a concave-convex or embossed shape or a larger surface to allow the molten joining member to flow evenly between the joining portion of the can and the cap in a molten state. A flow promoting part having a roughness is formed,
The secondary battery, characterized in that the melt bonding member is melted at 10 ° C to 120 ° C to include the operating temperature of the secondary battery but exclude the thermal runaway start temperature of the positive electrode material.
The method of claim 5,
The melt bonding member includes at least one of gallium (Ga), indium (In), cadmium (Cd) or bismuth (Bi).
The method of claim 5,
The molten bonding member is melted by a reflow apparatus including a heating furnace and a conveyor transported in the heating furnace,
And the molten bonding member is supplied to the inside of the heating furnace by the conveyor in a state of being coated on the junction between the can and the cap and melted.
The method of claim 7, wherein
The molten bonding member is a secondary battery, characterized in that the melting by hot air or infrared rays heating the inside of the heating furnace.
6. The method according to claim 1 or 5,
And the molten bonding member is melted when the temperature of the accommodating portion surrounded by the can and the cap rises to release the sealed state of the can and the cap.
In the method of manufacturing a secondary battery according to any one of claims 1 to 8,
Providing a metallic can including an accommodating part and an opening part accommodating the electrode assembly and the electrolyte together;
Providing a metallic cap positioned at the opening of the can to seal the can;
Providing a fusion bonding member having a melting point lower than a melting point of the can and the cap and between a junction of the can and the cap; And
And heating and melting the molten bonding member to bond the can and the cap.
The step of bonding the can and the cap is a method of manufacturing a secondary battery, characterized in that for heating the molten bonding member by locally heating or the reflow method.
The method of claim 10,
Local heating of the molten bonding member may be performed using any one of contact resistance, high frequency heating, laser, light beam, pulse heat, or hot-ram. Method for producing a secondary battery, characterized in that the heating locally.
12. The method of claim 11,
The laser uses a YAG laser absorbed by the fusion bonding member, and the light beam is obtained by using a xenon lamp or a halogen lamp with high brightness.
The method of claim 10,
The reflow method includes the operating temperature of the secondary battery, but the method of manufacturing a secondary battery, characterized in that when the molten bonding member is melted at 10 ℃ to 120 ℃ to exclude the thermal runaway start temperature of the positive electrode material.
The method of claim 13,
The molten bonding member includes at least one of gallium (Ga), indium (In), cadmium (Cd) or bismuth (Bi).
15. The method of claim 14,
The melt bonding member is a secondary battery manufacturing method characterized in that the melt by convection hot air, infrared or heat of condensation.
16. The method of claim 15,
And a cooling jig to prevent heat generated by hot air, infrared rays, or condensation heat from melting the fusion bonding member being transferred to the battery element accommodated in the accommodating part.

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