Cylindrical secondary battery

Abstract

The present invention relates to a cylindrical secondary battery, in which, when a center pin is inserted into a core of an electrode assembly and a cap assembly is coupled to an upper portion of a battery case, the inserted center pin supports the electrode assembly in a radial direction on an inner surface of the core by its elastic force, preventing collapse of the core and increasing adhesion between a positive electrode and a negative electrode. The cylindrical secondary battery according to the present invention includes a jelly-roll-shaped electrode assembly formed by winding up a separator between sheet-type positive and negative electrodes, a battery case housing the electrode assembly therein, a cap assembly coupled to the top of the battery case, and a center pin inserted into a core of the electrode assembly and supporting the electrode assembly in a radial direction on the inner circumferential surface of the core by elastic force, the center pin including a lengthy elastic body.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0159319 filed on November 24, 2020, and Korean Patent Application No. 10-2021-0160686 filed on November 19, 2021, and all contents disclosed in the documents of said Korean patent applications are incorporated as part of this specification.

[0002] The present invention relates to a cylindrical secondary battery in which, when a center pin is inserted into a core of an electrode assembly and a cap assembly is coupled to an upper portion of a battery case, the inserted center pin supports the electrode assembly in a radial direction on an inner surface of the core by elastic force, preventing collapse of the core and increasing adhesion between positive and negative electrodes. [Background technology]

[0003] In general, secondary batteries are batteries that can be charged and discharged, unlike primary batteries, which cannot be charged. They are widely used as power sources for electronic devices such as mobile phones, laptops, and camcorders, as well as electric vehicles.

[0004] Depending on the shape of the battery case, such secondary batteries can be classified into cylindrical batteries and prismatic batteries in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet.

[0005] A cylindrical battery generally includes an electrode assembly consisting of a positive electrode, a negative electrode, and a separator, a can that houses the electrode assembly and has an opening at its top, and a cap assembly that closes the opening at the top of the can. A positive electrode tab is connected to the positive electrode of the electrode assembly, and the positive electrode tab is welded to the cap assembly at the top of the opening. A negative electrode tab is connected to the negative electrode of the electrode assembly, and the negative electrode tab is welded to the bottom of the can.

[0006] In general, an electrode assembly is made by stacking a positive electrode, a separator, and a negative electrode, rolling it into a roll to form a jelly roll, and then storing it in a can. The center of the electrode assembly wound into a jelly roll has a hollow structure regardless of its outer diameter. However, this hollow structure has a high risk of collapse when the electrode assembly deteriorates, making it difficult to ensure the safety of the battery and causing a problem of a deterioration in battery performance.

[0007] In order to solve these problems, a cylindrical secondary battery 100 with a center pin 200 inserted therein has been developed as shown in Fig. 1. The cylindrical secondary battery 100 shown in Fig. 1 provides a cylindrical secondary battery 100 that exhibits excellent mechanical strength by inserting the center pin 200 into the wound electrode assembly, and prevents internal short circuit by preventing the end of the center pin 200 from contacting the electrode assembly even if the center pin 200 is deformed due to an external impact. However, even if the center pin 200 is inserted, there is still a problem that the adhesion of the electrode assembly is not high, and the rate of electrode reaction is also relatively low, so there is a demand for the development of a cylindrical secondary battery to improve the output of the battery. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been devised to solve the above problems, and an object of the present invention is to provide a method for manufacturing a battery case comprising the steps of: inserting a center pin into a core of an electrode assembly and connecting a cap assembly to an upper portion of a battery case; providing an elastic support for the inserted center pin in a radial direction on an inner surface of the core, thereby preventing collapse of the core and increasing adhesion between the positive and negative electrodes; and simultaneously functioning as a separate positive or negative electrode tab as necessary, thereby reducing resistance. [Means for solving the problem]

[0009] The cylindrical secondary battery according to the present invention includes an electrode assembly in a jelly roll form formed by winding up a separator between sheet-type positive and negative electrodes, a battery case in which the electrode assembly is housed, a cap assembly coupled to an upper part of the battery case, and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner surface of the core by elastic force, the center pin including an elastic body having a length.

[0010] The center pin may further include a lower support coupled to one end of the elastic body and in contact with the lower portion of the battery case.

[0011] The center pin may further include an upper support coupled to the other end of the elastic body and in contact with the cap assembly.

[0012] The center pin may further include a cylindrical body provided between the lower support and the upper support, and having a hollow space formed therein to accommodate an elastic body.

[0013] The body may be formed such that the axial length is shorter than the length of the elastic body.

[0014] The body may have an incision formed along an axial direction.

[0015] The body may be finished in a rolled configuration with the ends of the body formed at the incisions being hollowed out.

[0016] The elastic body is bent in the positive radial direction by the axial compressive stress acting on the lower support and the upper support, and can pressurize the body.

[0017] The body, the lower support, the upper support and the elastomer are non-conductors.

[0018] The upper support is a conductor, the lower support is a non-conductor, and the elastic body is a conductor.

[0019] A first positive electrode uncoated portion is formed at a winding start portion of the sheet-type positive electrode, one end of the first positive electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, and the elastic body may be provided to be joined to the first positive electrode uncoated portion protruding from the winding core portion of the electrode assembly.

[0020] The upper support is conductive, the lower support is non-conductive, and the elastomer and body are conductive.

[0021] A first positive electrode uncoated portion is formed at a winding start portion of the sheet-type positive electrode, one end of the first positive electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, and the body may be configured to be joined to the first positive electrode uncoated portion protruded from the winding core portion of the electrode assembly.

[0022] A second positive electrode uncoated portion and a positive electrode tab protruding from the second positive electrode uncoated portion may be further formed at the center of the sheet-type positive electrode, and the positive electrode tab may be bonded to an upper support.

[0023] The positive electrode tab may be bonded to the top surface of the upper support.

[0024] An insulating tape may be attached to a portion of the first positive electrode uncoated portion that does not protrude into the core of the electrode assembly.

[0025] The upper support is a non-conductor, the lower support is a conductor, and the elastic body is a conductor.

[0026] A first negative electrode uncoated portion is formed at a winding start portion of the sheet-type negative electrode, one end of the first negative electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, and the elastic body may be provided to be joined to the first negative electrode uncoated portion protruding from the winding core portion of the electrode assembly.

[0027] The upper support is a non-conductor, the lower support is a conductor, and the elastomer and the body are conductors.

[0028] A first negative electrode uncoated portion is formed at a winding start portion of the sheet-type negative electrode, one end of the first negative electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, and the body may be configured to be joined to the first negative electrode uncoated portion protruded from the winding core portion of the electrode assembly.

[0029] A second negative electrode uncoated portion and a negative electrode tab protruding from the second negative electrode uncoated portion may be further formed at a winding end portion of the sheet-type negative electrode, and the negative electrode tab may be bonded to the lower support.

[0030] An insulating tape may be attached to a portion of the first negative electrode uncoated portion that does not protrude into the core of the electrode assembly.

[0031] The elastic body may be one of a cylinder, a plate, or a ring.

[0032] The horizontal cross-sectional area of ​​the upper support may be greater than the horizontal cross-sectional area of ​​the core of the electrode assembly.

[0033] The diameter of the upper support may be greater than the diameter of the winding core of the electrode assembly. Effect of the Invention

[0034] The cylindrical secondary battery according to the present invention includes an electrode assembly in a jelly roll form in which a separator is interposed between sheet-type positive and negative electrodes and the electrode assembly is wound up, a battery case in which the electrode assembly is accommodated therein, a cap assembly coupled to the upper part of the battery case, and a center pin that is inserted into a winding core of the electrode assembly and supports the electrode assembly in a radial direction on an inner peripheral surface of the winding core by elastic force, the center pin including an elastic body having a length, and therefore, when the center pin is inserted into the winding core of the electrode assembly and the cap assembly is coupled to the upper part of the battery case, the inserted center pin supports the electrode assembly in a radial direction on an inner peripheral surface of the winding core by elastic force, preventing collapse of the winding core and increasing the adhesion between the positive and negative electrodes, and can also function as a separate positive electrode tab or negative electrode tab as necessary, thereby reducing resistance. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a cross-sectional view showing a conventional cylindrical secondary battery into which a center pin is inserted. [Diagram 2] 1 is a cross-sectional view showing a cylindrical secondary battery into which a center pin is inserted according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a perspective view showing a center pin of the cylindrical secondary battery according to the first embodiment of the present invention. [Figure 4] 1 is a perspective view showing a body of a center pin in a cylindrical secondary battery according to a first embodiment of the present invention; [Diagram 5] 3A to 3C are perspective views showing elastic bodies of various shapes that can be selected in a cylindrical secondary battery according to a first embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view showing a cylindrical secondary battery into which a center pin is inserted according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a cross-sectional view of a wound electrode assembly built into a cylindrical secondary battery according to Example 2 of the present invention. [Figure 8] FIG. 11 is a plan view of a sheet-type positive electrode of an electrode assembly built into a cylindrical secondary battery according to Example 2 of the present invention. [Figure 9] FIG. 11 is a cross-sectional view showing a cylindrical secondary battery into which a center pin is inserted according to a third embodiment of the present invention. [Figure 10] FIG. 11 is a cross-sectional view of a wound electrode assembly built into a cylindrical secondary battery according to Example 3 of the present invention. [Figure 11] FIG. 11 is a plan view of a sheet-type negative electrode of an electrode assembly built into a cylindrical secondary battery according to Example 3 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be embodied in several different forms, and is not limited to the following embodiments.

[0037] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the description or related prior art that may unnecessarily obscure the gist of the present invention will be omitted, and when adding reference symbols to components in each drawing in this specification, the same or similar reference symbols will be used for the same or similar components throughout the specification.

[0038] Furthermore, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts that are consistent with the technical ideas of the present invention, based on the principle that an inventor may appropriately define the concepts of terms in order to best explain his or her invention.

[0039] Example 1 Fig. 2 is a cross-sectional view showing a cylindrical secondary battery into which a center pin is inserted according to the first embodiment of the present invention. Fig. 3 is a perspective view showing a center pin in the cylindrical secondary battery according to the first embodiment of the present invention. Fig. 4 is a perspective view showing a body of the center pin in the cylindrical secondary battery according to the first embodiment of the present invention. Fig. 5 is a perspective view showing elastic bodies of various shapes that can be selected in the cylindrical secondary battery according to the first embodiment of the present invention.

[0040] 2 to 5, a cylindrical secondary battery 100 according to a first embodiment of the present invention includes an electrode assembly 110, a battery case 120, a cap assembly 130, and a center pin 140. As shown in FIG.

[0041] Here, the electrode assembly 110 is in the form of a jelly roll wound with a separator 113 interposed between sheet-type positive electrode 111 and negative electrode 112. Here, the separator 113 is interposed, which means that the separator 113 is located between each electrode by alternately stacking the positive electrode 111, separator 113, negative electrode 112, separator 113, positive electrode 111, etc., in order to prevent a short circuit between the positive electrode 111 and the negative electrode 112. The sheet-type positive electrode 111 includes a positive electrode current collector made of a metal thin plate having excellent conductivity, for example, aluminum (AL) foil, and a positive electrode active material layer coated on both sides thereof, and the sheet-type negative electrode 112 includes a negative electrode current collector made of a metal thin plate having excellent conductivity, for example, copper (Cu) or nickel (Ni) foil, and a negative electrode active material layer coated on both sides thereof. The area of ​​the current collector where the active material layer is not formed is a plain area, which means an area where the positive electrode or negative electrode current collector is exposed. A positive electrode tab 111-1 and a negative electrode tab 112-1 are formed on the positive electrode and negative electrode uncoated portions, respectively, and are extended to the upper and lower portions of the electrode assembly 110 by a certain length to be electrically connected to the cap assembly 130.

[0042] The wound electrode assembly 110 is housed inside the battery case 120, and a cap assembly 130 may be coupled to the upper part of the battery case 120. The cap assembly 130 is formed by sequentially stacking a safety vent, a current interruption device, a PTC device, a top cap, etc., and in particular, the top cap is seated and coupled to the top of the cap assembly 130 to transmit current generated in the secondary battery to the outside.

[0043] The cylindrical secondary battery 100 according to the first embodiment of the present invention may include a center pin 140, which is inserted into the winding core 114 of the electrode assembly 110. Here, the winding core 114 refers to the hollow interior formed in the wound electrode assembly 110 as shown in FIG.

[0044] When the length of the center pin 140 is formed to be longer than the axial length of the wound electrode assembly 110, the center pin 140 inserted into the winding core 114 of the electrode assembly 110 protrudes from the upper part of the wound electrode assembly 110. In addition, when the length of the center pin 140 is formed such that the protruding center pin 140 contacts the lower part of the cap assembly 130 and is finely pressed when the cap assembly 130 is coupled to the upper part of the battery case 120, the inserted center pin 140 supports the electrode assembly 110 in the radial direction on the inner peripheral surface of the winding core 114 by elastic force.

[0045] In this manner, when the center pin 140 is inserted into the winding core 114 of the electrode assembly 110, collapse of the winding core 114 can be prevented when the electrode assembly 110 deteriorates. At the same time, even when only the cap assembly 130 is attached, the center pin 140 supports the electrode assembly 110 in the radial direction on the inner surface of the winding core 114, thereby improving the electrode adhesion between the positive electrode 111 and the negative electrode 112 and improving battery performance.

[0046] Hereinafter, a detailed structure of the center pin 140 and a supporting function of the electrode assembly 110 will be described with reference to Fig. 3 or 4. Referring to Fig. 3, the center pin 140 may include a body 141, a lower support 142, an upper support 143, and an elastic body 144.

[0047] The body 141 is made of foil and has a cylindrical shape with a hollow space. The hollow space is formed in the cylindrical body 141, so that a space is provided inside in which the elastic body 144 can be provided. The cross-sectional shape of the body 141 is formed to correspond to the cross-sectional shape of the winding core 114, so that the center pin 140 can be easily inserted into the winding core 114 of the electrode assembly 110. The cylindrical body 141 is formed such that the height, i.e., the axial length, is shorter than the length of the elastic body 144, so that the body 141 does not come into contact with or be joined to the lower support 142 and the upper support 143. As a result, when the elastic body 144 presses the body 141 in the radial direction, the diameter of the body 141 may be changed without being affected by the lower support 142 and the upper support 143.

[0048] 4(a), the cylindrical body 141 may further have a cutout 141-1 cut along the axial direction, and when the elastic body 144 is bent to apply pressure to the body 141, the distance between the cutouts 141-1 is enlarged, and the diameter of the body 141 may be easily changed. Also, as shown in FIG. 4(b), the end of the body 141 formed at the cutout 141-1 is finished in a rolled form inside the hollow, thereby preventing damage to the cutout 141-1 of the body 141 formed of foil, and reinforcing the axial strength of the body 141 weakened by the cutout 141-1.

[0049] A long elastic body 144 may be provided in the hollow of the body 141, and the elastic body 144 may be formed of an elastic material, with one end connected to the lower support 142 and the other end connected to the upper support 143, the lower support 142 being in contact with the lower part of the battery case 120, and the upper support 143 being in contact with the lower part of the cap assembly 130. With this structure, the elastic body 144 may be bent in a positive radial direction by an axial compressive stress acting on the lower support 142 and the upper support 143, so that the body 141 may be pressurized. In addition, even when the elastic body 144 is bent, the ends of the elastic body 144 are fixed by the lower support 142 and the upper support 143, so that the center part of the elastic body 144 is bent in a positive radial direction, i.e., outward, so that the body 141 may be pressurized (see FIG. 3). The lower support 142 and the upper support 143 are not necessarily limited to shapes and sizes corresponding to each other, and one of the heights, i.e., the axial length, may be formed longer as necessary.

[0050] Meanwhile, the horizontal cross-sectional area of ​​the upper support 143 may be larger than the horizontal cross-sectional area of ​​the winding core of the electrode assembly 110. In addition, when the upper support 143 and the winding core of the electrode assembly 110 are formed in a circular shape, the diameter of the upper support 143 may be larger than the diameter of the winding core of the electrode assembly 110. In other words, the horizontal cross-sectional area or diameter of the upper support 143 is not necessarily the same as the diameter of the winding core of the electrode assembly 110, but the horizontal cross-sectional area or diameter of the upper support 143 may be larger than the cross-sectional area or diameter of the winding core of the electrode assembly 110. As a result, when the upper support 143 contacts the cap assembly 130, a more stable supporting force can be secured.

[0051] Alternatively, the center pin 140 may not have a body 141, but may be composed of only a lower support 142, an upper support 143, and an elastic body 144, so that the elastic body 144 directly presses the electrode assembly 110 when compressive stress acts in the axial direction.

[0052] The elastic body 144 is not limited in shape, but is preferably one of a cylindrical, plate-shaped, or ring-shaped, as shown in Fig. 5(a), (b), and (c), respectively. When the elastic body 144 is cylindrical, it is easy to manufacture and occupies a small volume, so that many elastic bodies 144 can be inserted inside the body 141. When the elastic body 144 is plate-shaped, it is easy to bend in the direction perpendicular to the surface, so that the bending direction of the elastic body 144 can be ensured to be consistent. When the elastic body 144 is ring-shaped, it has the advantage that the durability of the elastic body 144 is relatively strong, it is easy to bend, and a uniform elastic force can be ensured.

[0053] The body 141, lower support 142, upper support 143 and elastic body 144 of the center pin 140 may be made of a non-conductor. That is, when the center pin 140 is made of a non-conductor, the performance of the battery can be easily improved by simply inserting the center pin 140 without significantly modifying the existing battery structure, which is economical and can be applied to various types of cylindrical batteries.

[0054] As a result, when the cap assembly 130 is attached to the upper part of the battery case 120 due to the structure of the center pin 140 according to the first embodiment of the present invention, the inserted center pin 140 supports the electrode assembly 110 in the radial direction on the inner surface of the winding core part 114 by elastic force, thereby preventing the collapse of the winding core part 114 of the electrode assembly 110, and at the same time, a cylindrical secondary battery 100 can be provided which improves the battery performance by increasing the adhesion between the positive electrode 111 and the negative electrode 112.

[0055] Example 2 Fig. 6 is a cross-sectional view showing a cylindrical secondary battery with a center pin inserted according to Example 2 of the present invention. Fig. 7 is a cross-sectional view of a wound electrode assembly built into a cylindrical secondary battery according to Example 2 of the present invention. Fig. 8 is a plan view of a sheet-type positive electrode of an electrode assembly built into a cylindrical secondary battery according to Example 2 of the present invention.

[0056] The second embodiment of the present invention is different from the first embodiment in that the body 241, the elastic body 244, and the upper support 243 are formed of conductors, and the upper support 243 of the center pin can function as a positive electrode tab.

[0057] The contents common to the embodiment 1 will be omitted as much as possible, and the differences will be mainly described in the embodiment 2. In other words, if contents not described in the embodiment 2 are necessary, it is self-evident that they can be regarded as the contents of the embodiment 1.

[0058] 6, the upper support 243 of the center pin 240 of the cylindrical secondary battery 200 according to the second embodiment of the present invention is a conductor, the lower support 242 is a non-conductor, and the elastic body 244 is a conductor. Also, the body 241 of the center pin 240 is a conductor. As such, the body 241, the elastic body 244, and the upper support 243 of the center pin 240 are made of conductors, so that the upper support 243 can function as a positive electrode tab.

[0059] Hereinafter, a process in which the upper support 243 serves as a positive electrode tab will be described in detail with reference to FIGS.

[0060] First, a first positive electrode uncoated portion 211-2 may be formed at a winding start portion A of the sheet-type positive electrode 211. One end of the first positive electrode uncoated portion 211-2 is formed longer than one end of the separator 213, so that when the electrode assembly 210 is wound, the first positive electrode uncoated portion 211-2 protrudes into the winding core portion 214 of the electrode assembly 210, and the elastic body 244 of the center pin 240 may be provided to be joined to the first positive electrode uncoated portion 211-2 protruding from the winding core portion 214 of the electrode assembly 210. Alternatively, when the center pin 240 is provided with a body 241, the body 241 may be provided to be joined to the first positive electrode uncoated portion 211-2 protruding from the winding core portion 214 of the electrode assembly 210. That is, the sheet-type positive electrode 211, the body 241 of the center pin 240, the elastic body 244, and the upper support 243 are electrically connected to each other so as to function as a positive electrode tab, and the upper support 243 is joined to the lower end of the cap assembly 230 so as to be electrically connected to the outside.

[0061] In the case of the cylindrical secondary battery 200 according to the second embodiment of the present invention, the positive electrode tab 211-1 that is pulled out to a certain length from the upper part of the electrode assembly 210 and electrically connected to the cap assembly 230 can be omitted as necessary, thereby simplifying the internal structure of the battery and ensuring stable battery performance, and the manufacturing and attachment process of the positive electrode tab 211-1 can be omitted, thereby reducing the costs required for the same.

[0062] However, the second embodiment of the present invention may also be applied to a case where a separate positive electrode tab 211-1 is provided, as in a general battery structure. A second positive electrode uncoated portion 211-3 and a positive electrode tab 211-1 protruding from the second positive electrode uncoated portion 211-3 may be further formed in the center B of the sheet-type positive electrode 211. At this time, the positive electrode tab 211-1 may be bonded to the upper support 243, and the upper support 243 may be finally bonded to the cap assembly 230 and electrically connected thereto, thereby functioning as a positive electrode tab. In this structure, the sheet-type positive electrode 211 may be provided with a number of electrode tabs (positive electrode tabs), thereby improving the output of the battery and significantly improving performance. Meanwhile, the upper support 243 may be bonded to the cap assembly 230 by welding, but this is merely an example and the present invention is not limited thereto and may be bonded in various manners.

[0063] In addition, the positive electrode tab 211-1 may be attached to the upper support 243, preferably to the upper surface of the upper support 243. When the positive electrode tab 211-1 is attached to the upper surface of the upper support 243 in this manner, the positive electrode tab 211-1 attached to the upper surface of the upper support 243 comes into contact with the cap assembly 230 due to the elasticity of the center pin 240, even without separately welding the positive electrode tab 211-1 to the cap assembly 230, and thus the positive electrode tab 211-1 and the upper support 243 can function as a conductor. In addition, the positive electrode tab 211-1 may be attached more stably than when attached to the side of the upper support 243.

[0064] Meanwhile, the horizontal cross-sectional area of ​​the upper support 243 may be larger than the horizontal cross-sectional area of ​​the core of the electrode assembly 210 .

[0065] In addition, when the upper support 243 and the winding core of the electrode assembly 210 are formed in a circular shape, the diameter of the upper support 243 may be larger than the diameter of the winding core of the electrode assembly 210. That is, the horizontal cross-sectional area or diameter of the upper support 243 is not necessarily the same as the cross-sectional area or diameter of the winding core of the electrode assembly 210, but the horizontal cross-sectional area or diameter of the upper support 243 may be larger than the diameter of the winding core of the electrode assembly 210. This can ensure a more stable support force when the upper support 243 is in contact with the cap assembly 230. In addition, when the positive electrode tab 211-1 is joined to the upper support 243, there is an effect of improving the jointability. When the upper support 243 serves as a positive electrode tab, if necessary, the horizontal cross-sectional area or diameter of the upper support 243 may be larger than the horizontal cross-sectional area or diameter of the winding core of the electrode assembly 210 and the vertical (or axial) length may be shortened to reduce the resistance of the upper support 243.

[0066] In addition, an insulating tape T may be attached to a portion of the first positive electrode uncoated portion 211-2 that does not protrude into the inner part of the winding core part 214 of the electrode assembly 210, and an insulating tape T may also be attached to the second positive electrode uncoated portion 211-3. In this case, a short circuit that may occur when the separator 213 is damaged can be prevented, thereby improving the safety of the battery. In particular, when the insulating tape T is attached to the boundary portion between the first and second positive electrode uncoated portions 211-2 and 211-3 and the positive electrode active material layer, detachment of the active material due to a step difference between a portion coated with the active material and an uncoated portion can be prevented.

[0067] Example 3 Fig. 9 is a cross-sectional view showing a cylindrical secondary battery with a center pin inserted according to Example 3 of the present invention. Fig. 10 is a cross-sectional view of a wound electrode assembly built into a cylindrical secondary battery according to Example 3 of the present invention. Fig. 11 is a plan view of a sheet-type negative electrode of an electrode assembly built into a cylindrical secondary battery according to Example 3 of the present invention.

[0068] The third embodiment of the present invention differs from the first and second embodiments in that the body 341, the elastic body 344, and the lower support 342 are made of conductive materials, and the lower support 342 of the center pin 340 can function as a negative electrode tab.

[0069] The third embodiment will be described focusing on the differences between the first and second embodiments, while omitting the contents common to the first and second embodiments as much as possible. In other words, if the contents not described in the third embodiment are necessary, they can be regarded as the contents of the first and second embodiments.

[0070] 9, the upper support 343 of the center pin 340 of the cylindrical secondary battery 300 according to the third embodiment of the present invention is a non-conductor, the lower support 342 is a conductor, and the elastic body 344 is a conductor. Also, the body 341 of the center pin 340 is a conductor. As such, the body 341, the elastic body 344, and the lower support 342 of the center pin 340 are made of conductors, so that the lower support 342 can function as a negative electrode tab.

[0071] Hereinafter, a process in which the lower support 342 serves as a negative electrode tab will be described in detail with reference to FIGS.

[0072] First, a first negative electrode uncoated portion 312-2 may be formed at a winding start portion A of the sheet-type negative electrode 312. At this time, one end of the first negative electrode uncoated portion 312-2 is formed longer than one end of the separator 313, so that when the electrode assembly 310 is wound, the first negative electrode uncoated portion 312-2 may be protruded into the winding core portion 314 of the electrode assembly 310, and the elastic body 344 of the center pin 340 may be provided to be joined to the first negative electrode uncoated portion 312-2 protruded from the winding core portion 314 of the electrode assembly 310. Alternatively, when the center pin 340 is provided with a body 341, the body 341 may be provided to be joined to the first negative electrode uncoated portion 312-2 protruded from the winding core portion 314 of the electrode assembly 310. That is, the sheet-type negative electrode 312, the body 341 of the center pin 340, the elastic body 344, and the lower support 342 are electrically connected to each other so as to function as a negative electrode tab, and the lower support 342 is joined to the lower part of the battery case so as to be electrically connected to the outside.

[0073] In the case of the cylindrical secondary battery 300 according to the third embodiment of the present invention, the negative electrode tab 312-1, which is pulled out to a certain length from the lower portion of the electrode assembly 310 and electrically connected to the lower portion of the battery case 320, can be omitted as necessary, thereby simplifying the internal structure of the battery and ensuring stable battery performance, and omitting the manufacturing and attachment process of the negative electrode tab, thereby reducing the costs required therefor.

[0074] However, the third embodiment of the present invention may also be applied to a case where a negative electrode tab 312-1 is provided separately, as in a general battery structure. A second negative electrode uncoated portion 312-3 and a negative electrode tab 312-1 protruding from the second negative electrode uncoated portion 312-3 may be further formed at the winding end portion C of the sheet-type negative electrode 312. In this case, the negative electrode tab 312-1 may be joined to the lower support 342, and the lower support 342 may be finally joined to the lower end of the battery case 320 and electrically connected thereto, thereby functioning as a negative electrode terminal. In this case, the sheet-type negative electrode 312 may be provided with a number of electrode tabs (negative electrode tabs), thereby improving the output and significantly improving the performance of the battery.

[0075] Also, in the case of the cylindrical secondary battery according to the third embodiment of the present invention, the axial length of the upper support 343 may be longer than that of the lower support 342. When the lower support 342 serves as the negative electrode tab, the upper support 343 is formed relatively longer to prevent contact between the positive electrode tab 311-1 and the elastic body 344 electrically connected to the sheet-type negative electrode 312, thereby improving the safety of the battery.

[0076] An insulating tape T may be attached to a portion of the first negative electrode uncoated portion 312-2 that does not protrude into the inner part of the winding core part 314 of the electrode assembly 310, and an insulating tape T may also be attached to the second negative electrode uncoated portion 312-3. In this case, a short circuit that may occur when the separator 313 is broken can be prevented, thereby improving the safety of the battery. In particular, when the insulating tape T is attached to the boundary portion between the first and second negative electrode uncoated portions 312-2 and 312-3 and the negative electrode active material layer, detachment of the active material due to a step difference between a portion coated with the active material and an uncoated portion can be prevented.

[0077] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations of the present invention are possible within the technical spirit of the present invention and the equivalent scope of the following claims by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0078] 100, 200, 300: Cylindrical secondary battery 110, 210, 310: Electrode assembly 111, 211, 311: Positive electrode 112, 212, 312: Negative electrode 111-1, 211-1, 311-1: Positive electrode tab 112-1, 212-1, 312-1: Negative electrode tab 211-2: First positive electrode uncoated part 211-3: Second positive electrode uncoated part 312-2: First negative electrode uncoated part 312-3: Second negative electrode uncoated part 113, 213, 313: Separation membrane 114, 214, 314: Center part 120, 220, 320: Battery case 130, 230, 330: Cap assembly 140, 240, 340: Center pin 141, 241, 341: Body 141-1: Incision 142, 242, 342: Lower support 143, 243, 343: Upper support 144, 244, 344: Elastic body A: Winding start part B: Central part C: Winding end section T: Insulating tape

Claims

1. A jelly roll type electrode assembly in which a separator is interposed between sheet-type positive and negative electrodes and the electrodes are wound up; a battery case in which the electrode assembly is housed; a cap assembly coupled to an upper portion of the battery case; and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner circumferential surface of the core by elastic force; The center pin is It includes an elastic body having a length, The cylindrical secondary battery further includes a lower support member coupled to one end of the elastic body and in contact with a lower portion of the battery case.

2. The center pin is The cylindrical secondary battery according to claim 1 , further comprising an upper support coupled to the other end of the elastic body and in contact with the cap assembly.

3. The center pin is The cylindrical secondary battery of claim 2 , further comprising a cylindrical body provided between the lower support and the upper support, the cylindrical body having a hollow space therein so that the elastic body can be provided therein.

4. The body includes: The cylindrical secondary battery according to claim 3 , wherein the axial length is shorter than the length of the elastic body.

5. The body includes:

5. The cylindrical secondary battery according to claim 3, wherein an incision is formed along the axial direction.

6. The body includes: The cylindrical secondary battery according to claim 5 , wherein the end of the body formed at the cutout is finished in a rolled form with a hollow interior.

7. The elastic body is The cylindrical secondary battery according to claim 3 , wherein the lower support and the upper support are bent in a positive radial direction by an axial compressive stress acting on the lower support and the upper support to compress the body.

8. A cylindrical secondary battery described in any one of claims 3 to 7, wherein the body, the lower support, the upper support and the elastic body are non-conductors.

9. A jelly roll type electrode assembly in which a separator is interposed between sheet-type positive and negative electrodes and the electrodes are wound up; a battery case in which the electrode assembly is housed; a cap assembly coupled to an upper portion of the battery case; and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner circumferential surface of the core by elastic force; The center pin is It includes an elastic body having a length, The center pin is a lower support member coupled to one end of the elastic body and in contact with a lower portion of the battery case, The center pin is an upper support coupled to the other end of the elastic body and in contact with the cap assembly; the upper support is a conductor, the lower support is a nonconductor, and the elastic body is a conductor; a first positive electrode uncoated portion is formed at a winding start portion of the sheet-type positive electrode, one end of the first positive electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, The elastic body is configured to be joined to the first positive electrode uncoated portion protruding from the winding core of the electrode assembly.

10. A jelly roll type electrode assembly in which a separator is interposed between sheet-type positive and negative electrodes and the electrodes are wound up; a battery case in which the electrode assembly is housed; a cap assembly coupled to an upper portion of the battery case; and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner circumferential surface of the core by elastic force; The center pin is It includes an elastic body having a length, The center pin is a lower support member coupled to one end of the elastic body and in contact with a lower portion of the battery case, The center pin is an upper support coupled to the other end of the elastic body and in contact with the cap assembly; The center pin is The elastic body may further include a cylindrical body provided between the lower support and the upper support, the cylindrical body having a hollow space therein, and the elastic body may be provided therein. The upper support is a conductor, the lower support is a non-conductor, and the elastic body and the body are conductors.

11. a first positive electrode uncoated portion is formed at a winding start portion of the sheet-type positive electrode, one end of the first positive electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, The cylindrical secondary battery of claim 10 , wherein the body is configured to be joined to the first positive electrode uncoated portion protruding from a core portion of the electrode assembly.

12. a second positive electrode uncoated portion is formed at a center portion of the sheet-type positive electrode, and a positive electrode tab is protruded from the second positive electrode uncoated portion; The cylindrical secondary battery according to claim 9 , wherein the positive electrode tab is joined to the upper support.

13. The positive electrode tab is The cylindrical secondary battery according to claim 12 , which is bonded to the upper surface of the upper support.

14. 12. The cylindrical secondary battery of claim 9, wherein an insulating tape is attached to a portion of the first positive electrode uncoated portion that does not protrude into the core of the electrode assembly.

15. A jelly roll type electrode assembly in which a separator is interposed between sheet-type positive and negative electrodes and the electrodes are wound up; a battery case in which the electrode assembly is housed; a cap assembly coupled to an upper portion of the battery case; and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner circumferential surface of the core by elastic force; The center pin is It includes an elastic body having a length, The center pin is a lower support member coupled to one end of the elastic body and in contact with a lower portion of the battery case, The center pin is an upper support coupled to the other end of the elastic body and in contact with the cap assembly; the upper support is a non-conductor, the lower support is a conductor, and the elastic body is a conductor; a first negative electrode uncoated portion is formed at a winding start portion of the sheet-type negative electrode, one end of the first negative electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, The elastic body is configured to be joined to the first negative electrode uncoated portion protruded from the core portion of the electrode assembly.

16. A jelly roll type electrode assembly in which a separator is interposed between sheet-type positive and negative electrodes and the electrodes are wound up; a battery case in which the electrode assembly is housed; a cap assembly coupled to an upper portion of the battery case; and a center pin that is inserted into a core of the electrode assembly and supports the electrode assembly in a radial direction on an inner circumferential surface of the core by elastic force; The center pin is It includes an elastic body having a length, The center pin is a lower support member coupled to one end of the elastic body and in contact with a lower portion of the battery case, The center pin is an upper support coupled to the other end of the elastic body and in contact with the cap assembly; The center pin is The elastic body may further include a cylindrical body provided between the lower support and the upper support, the cylindrical body having a hollow space therein, and the elastic body may be provided therein. The upper support is a non-conductor, the lower support is a conductor, and the elastic body and the body are conductors.

17. a first negative electrode uncoated portion is formed at a winding start portion of the sheet-type negative electrode, one end of the first negative electrode uncoated portion is formed longer than one end of the separator and protrudes into a winding core portion of the electrode assembly, The cylindrical secondary battery of claim 16 , wherein the body is configured to be joined to the first negative electrode uncoated portion protruding from a core portion of the electrode assembly.

18. a second negative electrode uncoated portion and a negative electrode tab protruding from the second negative electrode uncoated portion are further formed at a winding end portion of the sheet-type negative electrode, The cylindrical secondary battery according to claim 15 , wherein the negative electrode tab is joined to the lower support.

19. The cylindrical secondary battery of claim 15 or 17, wherein an insulating tape is attached to a portion of the first negative electrode uncoated portion that does not protrude into the inner part of the winding core of the electrode assembly.

20. The cylindrical secondary battery according to claim 1 , wherein the elastic body has one of a cylindrical shape, a plate shape, and a ring shape.

21. The horizontal cross-sectional area of ​​the upper support is The cylindrical secondary battery according to claim 2 , wherein the horizontal cross-sectional area is larger than the horizontal cross-sectional area of ​​the winding core of the electrode assembly.

22. The diameter of the upper support is The cylindrical secondary battery according to claim 2 , wherein the diameter of the cylindrical secondary battery is larger than the diameter of the core of the electrode assembly.

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