Title of invention: Cylindrical secondary battery having a multi-layered battery case and its manufacturing method
Technical field
[One]
This application claims the benefit of priority based on Korean Patent Application No. 2019-0067867 filed on June 10, 2019, and all contents disclosed in the documents of the Korean patent application are incorporated as part of this specification.
[2]
The present invention relates to a cylindrical secondary battery having a multi-layered battery case and a method for manufacturing the same, and more particularly, ultrasonic welding only a predetermined part of a dissimilar metal plate made of copper and nickel to be used as a plate for an electric case, and a negative electrode tab The present invention relates to a cylindrical secondary battery having a multi-layered battery case that is of the same type as copper constituting the inner layer of the battery case, guaranteeing welding reliability and providing a high-output secondary battery, and a method of manufacturing the same.
Background
[3]
As technology development and demand for mobile devices increase, rechargeable secondary batteries are used as energy sources for various mobile devices. Secondary batteries are also attracting attention as energy sources such as electric vehicles and hybrid electric vehicles that are proposed as alternatives to conventional gasoline vehicles and diesel vehicles that use fossil fuels.
[4]
Depending on the shape of the battery case, secondary batteries are classified into cylindrical and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet. .
[5]
The electrode assembly built into the battery case is a charge/discharge power generator consisting of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode, and the separator is interposed between the positive electrode and the negative electrode in the form of a long sheet coated with an active material. It is classified into a wound jelly-roll type and a stacked type sequentially stacked with a separator interposed between a plurality of positive and negative electrodes of a predetermined size. Among them, the jelly-roll type electrode assembly is easy to manufacture and has the advantage of high energy density per weight.
[6]
Meanwhile, in such a secondary battery, a negative electrode tab extending from the negative electrode is welded to the inner lower surface of the battery case by resistance welding. Resistance welding is generally performed by inserting the first welding rod into the winding core of the electrode assembly to make contact with the negative electrode tab, and applying current while the second welding rod is in close contact with the outer surface of the lower end of the battery case at a position opposite to the first welding rod. . When a plurality of conductors are in contact with each other, heat is generated by the contact resistance, and welding is performed by this heat, and the heat generated at the contact portion is generated more as the contact resistance is increased. The contact resistance increases as the contact area between conductors decreases, and the lower inner surface of the battery case of a general cylindrical secondary battery and the negative electrode tab are formed in a smooth plane, so that the contact resistance is small, so there is a problem that weldability decreases.
[7]
In this regard, Patent Document 1 discloses a cylindrical secondary battery that facilitates welding of the negative electrode tab by forming a protrusion on the lower plate of the battery case to increase the contact resistance when contacting the negative electrode tab. The negative electrode tab is deformed by a protrusion positioned on the fusion surface between the negative electrode tab and the negative electrode tab has a vulnerability that may cause a ripple phenomenon.
[8]
In addition, in order to weld a negative electrode tab made of a low-resistance metal, an embossed structure is formed on the negative electrode tab to improve welding processability, but a negative electrode tab made of a low-resistance metal generates heat when welding with a relatively high-resistance battery case. This is remarkably low, it is not possible to secure a desirable level of fairness and there is a problem that a number of secondary batteries with poor welding occur.
[9]
Further, Patent Document 2 discloses a secondary battery including a clad negative electrode tab formed in a two-layer structure of nickel and copper. However, the clad negative electrode tab formed with a two-layer structure of nickel and copper has a high resistance compared to the negative electrode tab made of copper, so the maximum allowable current and heat dissipation characteristics are low, and as a result, a secondary battery having high output cannot be provided.
[10]
(Prior technical literature)
[11]
(Patent Document 1) Korean Patent Publication No. 2007-0082969
[12]
(Patent Document 2) Korean Patent Publication No. 2009-0132494
Detailed description of the invention
Technical challenge
[13]
In order to solve the above problems, an object of the present invention is to provide a cylindrical secondary battery capable of increasing output due to good allowable current and heat dissipation characteristics, and a manufacturing method thereof.
[14]
In addition, an object of the present invention is to provide a cylindrical secondary battery capable of reducing production cost by not using expensive materials such as copper-nickel clad and a method of manufacturing the same.
[15]
In addition, it is an object of the present invention to provide a cylindrical secondary battery and a method of manufacturing the same, which can facilitate resistance welding by using a negative electrode tab and a battery case made of the same metal, and consequently lower the defect rate of a product.
Means of solving the task
[16]
Cylindrical secondary battery having a multi-layered battery case according to the present invention for solving the above problems, a positive electrode 110, a negative electrode 120, a separator interposed between the positive electrode 110 and the negative electrode 120 (130), an electrode assembly 100 including an anode tab 140 having one side connected to the anode 110, and a cathode tab 150 having one side connected to the cathode 120; A current blocking member 210 positioned above the electrode assembly 100 that blocks current when the internal pressure of the battery increases, a safety vent 230 connected to the top of the current blocking member 210, and a shape protruding upward. A cap assembly 200 including a top cap 250 having a lower surface of the outer circumferential surface in contact with the upper surface of the safety vent 230; And a cylindrical battery case 300 accommodating the electrode assembly 100 and the cap assembly 200, wherein the cylindrical battery case 300 includes an inner layer 310 adjacent to the electrode assembly 100 and the A welded portion 330 made of an outer layer 320 made of a material having a relatively lower thermal conductivity than the inner layer 310, and fixed only a predetermined area to the inner layer 310 and the outer layer 320 by welding. It characterized in that it is provided.
[17]
In addition, in a cylindrical secondary battery having a multi-layered battery case of the present invention, the inner layer 310 may be copper and the outer layer 320 may be a nickel or nickel plated steel sheet.
[18]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding portion 330 is preferably formed by ultrasonic welding.
[19]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding portion 330 is preferably located on the lower surface of the battery case (300).
[20]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding portion 330 may have a circular band shape smaller than the inner diameter of the battery case 300.
[21]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding part 330 may be located on the side of the battery case 300.
[22]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding part 330 may be located on the upper surface of the battery case 300.
[23]
In addition, in the cylindrical secondary battery having a multi-layered battery case of the present invention, the welding part 330 may be located on two or more of the lower surface, the side surface, and the upper surface of the battery case 300.
[24]
The method for manufacturing a cylindrical secondary battery having a multilayered battery case according to the present invention comprises: preparing a laminated plate by overlapping a copper plate and a nickel or nickel plated steel plate; Forming a weld by welding only a predetermined area of ​​the laminated plate; Deep drawing the laminated plate to prepare a cylindrical battery case in which the lower surface and the side surface are bent at a predetermined angle and the upper part is opened; Accommodating an electrode assembly and a cap assembly in the cylindrical battery case; And it characterized in that it comprises the step of fixing the upper portion of the cylindrical battery case.
[25]
In addition, in the method for manufacturing a cylindrical secondary battery having a multi-layered battery case of the present invention, the welding is preferably ultrasonic welding.
[26]
In addition, in the method of manufacturing a cylindrical secondary battery having a multi-layered battery case of the present invention, it is preferable that the welding portion 330 has a circular band shape.
[27]
In addition, in the method for manufacturing a cylindrical secondary battery having a multi-layered battery case of the present invention, the circular band may have two or more different inner diameters from the same virtual center point.
Brief description of the drawing
[28]
1 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a first embodiment of the present invention.
[29]
2 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a second exemplary embodiment of the present invention.
[30]
3 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a third exemplary embodiment of the present invention.
[31]
4 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a fourth exemplary embodiment of the present invention.
[32]
5 is a conceptual diagram illustrating a welding method of a multilayer plate for a battery case applied to the first embodiment of the present invention.
[33]
6 is a conceptual diagram illustrating a method of welding a multilayer plate for a battery case applied to a fourth embodiment of the present invention.
[34]
7 is a conceptual diagram illustrating a manufacturing process of a cylindrical secondary battery having a multi-layered battery case according to a first embodiment of the present invention.
Mode for carrying out the invention
[35]
In the present application, terms such as "comprise", "have" or "have" are intended to designate the presence of features, numbers, steps, components, parts, or combinations thereof described in the specification, but one or more other It is to be understood that it does not preclude the presence or addition of features, numbers, steps, actions, components, parts, or combinations thereof.
[36]
In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of a certain component does not exclude other components unless specifically stated to the contrary, but means that other components may be further included.
[37]
Hereinafter, a cylindrical secondary battery having a multi-layered battery case according to the present invention and a manufacturing method thereof will be described with reference to the accompanying drawings.
[38]
[39]
1 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a first embodiment of the present invention.
[40]
Referring to FIG. 1, a cylindrical secondary battery having a multilayered battery case according to a first embodiment of the present invention includes an electrode assembly 100, a cap assembly 200, and a cylindrical battery case 300 accommodating them. ).
[41]
The electrode assembly 100 is a jelly-roll type electrode assembly having a structure in which a separator 130 is interposed between a long sheet-shaped anode 110 and a cathode 120 and then wound, or a rectangular anode 110 and a cathode ( 120) a stacked electrode assembly composed of unit cells of a structure stacked with the separation membrane 130 interposed therebetween, or a stack-folding electrode assembly in which the unit cells are wound by a long separation film, or the The unit cells may be stacked with a separator interposed therebetween, and may be formed of a lamination-stack type electrode assembly or the like attached to each other.
[42]
The positive electrode tab 140 attached to the top of the electrode assembly 100 is electrically connected to the cap assembly 200, and the negative electrode tab 150 attached to the lower part of the electrode assembly 100 is connected to the bottom of the battery case 300. .
[43]
Here, the negative electrode tab 150 is preferably made of a copper material having a low resistance and a high maximum allowable current.
[44]
Meanwhile, an insulating member (not shown) may be positioned on the electrode assembly 100, and this insulating member (not shown) serves to insulate between the electrode assembly 100 and the cap assembly 200.
[45]
The cap assembly 200 is located on the insulating member (not shown) and is electrically connected to the positive electrode tab 130 attached to the top of the electrode assembly 100, and is coupled to the upper open end of the battery case 300 to provide a battery case. (300) The electrode assembly 100 accommodated inside is sealed.
[46]
Specifically, in the cap assembly 200, a current blocking member 210, a current blocking gasket 220, a safety vent 230, a PTC element 240, and a top cap 250 are sequentially stacked from below, and the current A clamping gasket 260 is positioned on the outer rim of the blocking member 210 and the top cap 250.
[47]
The positive electrode tab 140 is connected to a predetermined position under the current blocking member 210. Although the drawing shows that the current blocking member 210 has a flat plate shape, the center portion may be convex upward.
[48]
A safety vent 230 is disposed above the current blocking member 210 so that the center portion protrudes downward. When the pressure inside the battery increases, the safety vent 230 cuts off current and exhausts gas, and one side of the safety vent 230 is in contact with the PTC element 240 and the edge end face of the crimping gasket 260 is disposed.
[49]
The current blocking gasket 220 is positioned so that the current blocking member 210 and the safety vent 230 are electrically insulated except for the downward protruding portion of the current blocking member 210 and the safety vent 230 do.
[50]
The PTC (Positive Temperature Coefficient) element 240 for blocking current by increasing the resistance when the temperature inside the battery rises is in contact with the safety vent 230 on one side of the edge and the inner edge of the top cap 250 on the other side. have.
[51]
In the case of a cylindrical secondary battery, gas is generated due to a number of causes, such as external shock, which increases internal pressure, which may lead to ignition or explosion.
[52]
The current blocking member 210 and the safety vent 230 are for facilitating the discharge of gas that causes the increase in the internal pressure of the battery, and when the inside of the battery is above a predetermined pressure, the current blocking member 210 and safety A predetermined portion of the vent 230 is broken to prevent an explosion.
[53]
The top cap 250 located at the top seals the upper open end of the battery case 300 and forms a positive terminal.
[54]
A general cylindrical secondary battery performs a crimping process and a beading process to fix the cap assembly 200.
[55]
When performing a crimping process and a beading process on the edge of the current blocking member 210, the safety vent 230, the PTC element 240, and the top cap 250, that is, the outer circumferential surface, these unit parts are A clamping gasket 260 is interposed so as to prevent deformation or damage and to improve the adhesion between the current blocking member 210 and the top cap 250. Here, the clamping gasket 260 is not particularly limited as long as it is a material having a predetermined elasticity and durability, and for example, polybutylene terephthalate (PBT), polyphenylene sulfide (PPS) ), Perfluoroalkoxy (PFA).
[56]
Subsequently, the battery case 300 accommodates the electrode assembly 100 and the cap assembly 200, and after the negative electrode tab 150 extends downward so that the bottom of the battery case 300 can function as a negative electrode, the battery case 300 is connected to the floor.
[57]
Here, the battery case 300 has a multi-layer structure composed of an inner layer 310 and an outer layer 320. Specifically, the inner layer 310 is connected to directly contact the negative electrode tab 150, and the outer layer 320 is located outside the inner layer 310.
[58]
The outer layer 320 is preferably made of a material having a relatively lower thermal conductivity than the inner layer 310, for example, the inner layer 310 is a plate made of a copper material, and the outer layer 320 is nickel or nickel plated It can be a grater.
[59]
Further, at the edge of the bottom surface of the battery case 300, a circular band-shaped welding part 330 is formed to securely connect the inner layer 310 and the outer layer 320 to each other so as to be electrically connected.
[60]
That is, in the battery case 300 according to the first embodiment of the present invention, each of the inner layer 310 and the outer layer 320 is adhesively fixed to each other only by a welding portion 330 formed through ultrasonic welding.
[61]
Therefore, when the negative electrode tab 150 made of copper material is employed, the maximum allowable current and heat dissipation characteristics are excellent, so that a high-output battery can be provided. Thus, it is easy to fix the negative electrode tab 150 to the inner layer 310 by resistance welding, and there is an advantage in that there is no need to use an expensive copper-nickel clad.
[62]
2 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a second exemplary embodiment of the present invention. Only the position of the welding portion 330 is different from the first embodiment of FIG. 1. That is, in the second embodiment, the welding portion 330 may be positioned at a predetermined side portion instead of the bottom edge of the battery case 300.
[63]
3 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a third exemplary embodiment of the present invention. Only the position of the welding portion 330 is different from the first embodiment of FIG. 1. That is, in the third embodiment, the welding portion 330 may be positioned at a predetermined portion of the upper surface instead of the edge of the bottom surface of the battery case 300.
[64]
4 is a cross-sectional view of a cylindrical secondary battery having a multi-layered battery case according to a fourth exemplary embodiment of the present invention. In the first embodiment of FIG. 1, the welding portion 330 is located only at the edge of the bottom surface, but in the fourth embodiment, the welding portion 330 may be further formed at a predetermined portion of the upper surface of the battery case 300.
[65]
Of course, although not shown in the drawing, welding portions 330 on the bottom edge and side surfaces of the battery case 300, or the side and top surfaces of the battery case 300, or the bottom edge, side and top surfaces of the battery case 300, respectively. Can be formed.
[66]
Next, a method of welding a multilayer plate for a battery case will be described with reference to FIGS. 5 to 6.
[67]
5 is a conceptual diagram illustrating a welding method of a multilayer plate for a battery case applied to the first embodiment of the present invention, and FIG. 5A is a cross-sectional view showing a state in which the multilayer plate is seated on an ultrasonic welding device. Specifically, an inner layer 310 and an outer layer 320 having a predetermined width and length are placed on the die 410 in a state of being overlapped with each other, and an ultrasonic horn 420 is positioned thereon.
[68]
When a predetermined range of ultrasonic waves is applied together with pressure, the temperature of the inner layer 310 and the outer layer 320 of the corresponding portion through the tip 421 rises due to vibrational frictional heat, and the ultrasonic welding principle is known. Since it corresponds to the technology, a detailed description is omitted.
[69]
5(B) is a view of the multilayer plate as viewed from above, and is a view showing the position and shape of the welded portion 330 bonded by ultrasonic waves. That is, when the ultrasonic horn 420 or the laminated plate made of the inner layer 310 and the outer layer 320 is rotated and welded, a circular band-shaped weld 330 having a predetermined inner diameter is formed, and the inner layer 310 And the outer layer 320 are welded to each other.
[70]
6 is a conceptual diagram illustrating a welding method of a multilayer plate for a battery case applied to a fourth embodiment of the present invention. Welding is performed with the ultrasonic horn 420 in which the four tips 421 are spaced apart a predetermined distance (refer to FIG. 6(A)), and when welding while rotating the ultrasonic horn 420 or the laminated plate, the same virtual center point is referenced. As a result, it is possible to form two circular band-shaped welds 330 having different inner diameters (see FIG. 6(B)).
[71]
Of course, even with the ultrasonic horn 420 provided with one tip 421, a plurality of welds having a predetermined shape can be formed by rotating the laminated plate or the ultrasonic horn 420, and the welds in various shapes instead of circular bands It is also possible to form 330.
[72]
Subsequently, a method of manufacturing a cylindrical secondary battery having a multi-layered battery case according to the present invention will be described. 7 is a conceptual diagram illustrating a manufacturing process of a cylindrical secondary battery having a multi-layered battery case according to a first embodiment of the present invention.
[73]
The method for manufacturing a cylindrical secondary battery according to the present invention comprises: preparing a laminated plate, welding only a predetermined area of ​​the laminated plate, dip drawing the welded laminated plate to prepare a cylindrical battery case with an open top, and a cylindrical battery And accommodating the electrode assembly and the cap assembly in the case, and fixing the upper portion of the cylindrical battery case.
[74]
Since the step of preparing the laminated plate and welding only a predetermined area has been described with reference to FIG. 5, it will be omitted.
[75]
In the step of preparing the cylindrical battery case, the laminated plate material on which the welding part 330 is formed is placed on the upper part of the mold 510 having a predetermined inner diameter and height, and pressed with a punch 520 from the upper part of the laminated plate material, that is, by deep drawing to It is molded so that the side is bent at a predetermined angle and the top is open.
[76]
Here, the welding part 330 is positioned in the vertical surface of the mold 510 so that it can be located at the edge of the bottom surface of the cylindrical battery case. If, in the case of forming the battery case according to the second embodiment, the welding portion 330 of the laminated plate should be larger than the bottom surface of the mold 510, and the welding portion 333 should be positioned so as to surround the bottom surface of the mold 510. Ham is self-evident.
[77]
The electrode assembly 100 and the cap assembly 200 are sequentially accommodated in the upper opening of the battery case prepared in this way, and then the jig 530 is pressed to perform a crimping process and a beading process.
[78]
Of course, it is natural that a resistance welding process must be additionally performed in order to connect the negative electrode tab 140 made of copper to the inner layer 310 of the battery case 300 made of the same material.
[79]
[80]
Specific parts of the present invention have been described in detail above, and for those of ordinary skill in the art, these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereby. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and scope of the technical idea, and it is natural that such modifications and modifications fall within the appended claims.
[81]
(Explanation of code)
[82]
100: electrode assembly
[83]
110: anode 120: cathode
[84]
130: separator 140: anode tab
[85]
150: cathode tab
[86]
200: cap assembly
[87]
210: current blocking member 220: current blocking gasket
[88]
230: safety vent 240: PTC element
[89]
250: top cap 260: crimping gasket
[90]
300: battery case
[91]
310: inner layer 320: outer layer
[92]
330: welding part
[93]
410: die 420: ultrasonic horn
[94]
421: tips
[95]
510: mold 520: punch
[96]
530: jig
Industrial availability
[97]
Cylindrical secondary battery having a multi-layered battery case according to the present invention, since both the negative electrode tab and the inner layer of the battery case are made of copper material of the same type, thus guaranteeing the reliability of welding, which may contribute to a reduction in product defect rates.
[98]
In addition, in the cylindrical secondary battery having a multi-layered battery case according to the present invention, since both the negative electrode tab and the inner layer of the battery case are made of copper material having excellent maximum allowable current and heat dissipation characteristics, heat diffusion is improved, thus providing a high-power secondary battery. can do.
[99]
In addition, in the cylindrical secondary battery having a multi-layered battery case according to the present invention, an expensive copper-nickel clad is not used, and only a predetermined portion of a multi-layered plate made of copper and nickel, which is a heterogeneous metal, is ultrasonically welded to be used as a plate for a battery case. Therefore, manufacturing cost can be reduced.
Claims
[Claim 1]
An electrode assembly comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, a positive electrode tab connected to one side of the positive electrode, and a negative electrode tab connected to the negative electrode on one side; A current blocking member located above the electrode assembly that blocks current when the internal pressure of the battery increases, a safety vent connected to the upper end of the current blocking member, and a tower in which the lower surface of the outer circumferential surface is in contact with the upper surface of the outer circumferential surface of the safety vent in a shape protruding upward A cap assembly including a cap; And a cylindrical battery case accommodating the electrode assembly and the cap assembly, wherein the cylindrical battery case includes an inner layer adjacent to the electrode assembly and an outer layer of a material having a relatively lower thermal conductivity than the inner layer, and the Cylindrical secondary battery having a multi-layered battery case, characterized in that the inner layer and the outer layer are provided with welding portions fixed only a predetermined area by welding.
[Claim 2]
The cylindrical secondary battery according to claim 1, wherein the inner layer is copper and the outer layer is a nickel or nickel plated steel sheet.
[Claim 3]
The cylindrical secondary battery according to claim 1, wherein the welding part is formed by ultrasonic welding.
[Claim 4]
The cylindrical secondary battery according to claim 3, wherein the welding part is located on a lower surface of the battery case.
[Claim 5]
The cylindrical secondary battery according to claim 4, wherein the welding part has a circular band shape smaller than an inner diameter of the battery case.
[Claim 6]
The cylindrical secondary battery according to claim 3, wherein the welding part is located on a side of the battery case.
[Claim 7]
The cylindrical secondary battery according to claim 3, wherein the welding part is located on an upper surface of the battery case.
[Claim 8]
The cylindrical secondary battery according to claim 3, wherein the welding part is located on at least two of a lower surface, a side surface, and an upper surface of the battery case.
[Claim 9]
Preparing a laminated plate by overlapping a copper plate and a nickel or nickel plated steel plate; Forming a weld by welding only a predetermined area of ​​the laminated plate; Deep drawing the laminated plate to prepare a cylindrical battery case in which the lower surface and the side surface are bent at a predetermined angle and the upper part is opened; Accommodating an electrode assembly and a cap assembly in the cylindrical battery case; And fixing the upper portion of the cylindrical battery case; a method for manufacturing a cylindrical secondary battery having a multi-layered battery case comprising a.
[Claim 10]
The method of claim 9, wherein the welding is ultrasonic welding.
[Claim 11]
The method of claim 9, wherein the welding part has a circular strip shape.
[Claim 12]
The method of claim 11, wherein the circular band has two or more different inner diameters from the same virtual center point.