Secondary battery and method for manufacturing the same

Abstract

The present invention relates to a secondary battery and a method for manufacturing the secondary battery. The secondary battery according to the present invention includes an electrode assembly in which electrodes and separators are alternately stacked and wound up, a battery case in which the electrode assembly and an electrolyte are contained, and a fixing tape that adheres to the outer surface of the electrode assembly to prevent unwinding. When the fixing tape is impregnated with the electrolyte, the fixing force that prevents unwinding of the electrode assembly weakens, allowing the electrode assembly to unwind and filling the space between the battery case and the electrode assembly.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0102758, filed on August 14, 2020, the entire contents of which are incorporated herein by reference. The present invention relates to a secondary battery and a method for manufacturing a secondary battery. [Background technology]

[0002] Unlike primary batteries, secondary batteries are rechargeable and have the potential to be small and have large capacity, and as such, they have been the subject of much research and development in recent years. As technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is rapidly increasing.

[0003] Secondary batteries are classified into coin type batteries, cylindrical type batteries, prismatic type batteries, and pouch type batteries according to the shape of the battery case. In secondary batteries, the electrode assembly attached inside the battery case is a chargeable and dischargeable power generating element having a laminated structure of electrodes and separators.

[0004] Electrode assemblies can be broadly classified into a jelly-roll type in which a separator is interposed between a sheet-like positive electrode and a negative electrode coated with an active material and the electrode is wound up; a stack type in which a plurality of positive electrodes and negative electrodes are sequentially stacked with a separator interposed therebetween; and a stack / folding type in which a stack type unit cell is wound up with a long separating film.

[0005] Among these, a jelly-roll type electrode assembly is widely used since it has advantages of being easy to manufacture and having a high energy density per weight. Cylindrical batteries including jelly roll type electrode assemblies use finishing tapes made of PET and PP materials to prevent the jelly roll from unraveling and to protect the jelly roll from external damage. Jelly rolls secured with PET or PP finishing tape have the problem of moving around inside the cells if there is an open space inside the cells. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 10-2016-0010121 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENT An aspect of the present invention is to provide a secondary battery capable of preventing loose movement of an electrode assembly and a method for manufacturing the secondary battery.

[0008] Another aspect of the present invention is to provide a secondary battery capable of reducing the battery resistance and a method for manufacturing the secondary battery. [Means for solving the problem]

[0009] A secondary battery according to an embodiment of the present invention includes an electrode assembly in which electrodes and separators are alternately stacked and wound up, a battery case in which the electrode assembly and an electrolyte are contained, and a fixing tape that is adhered to an outer surface of the electrode assembly to prevent unwinding. When the fixing tape is impregnated with the electrolyte, the fixing force of the fixing tape that prevents the unwinding is weakened, so that the electrode assembly unwinds and the space between the battery case and the electrode assembly is filled.

[0010] Meanwhile, a method for manufacturing a secondary battery according to an embodiment of the present invention includes a winding process of alternately stacking electrodes and separators and winding them to form an electrode assembly, a tape adhering process of adhering a fixing tape to an outer surface of the electrode assembly to prevent unwinding, and a accommodating process of accommodating the electrode assembly and an electrolyte in a battery case. In the tape adhering process, the fixing tape whose fixing force that prevents unwinding when impregnated with the electrolyte is used, and in the accommodating process, the fixing force of the fixing tape is weakened when the electrolyte is accommodated, so that the electrode assembly unwinds and a space between the battery case and the electrode assembly is filled. Effect of the Invention

[0011] According to the present invention, the fixing tape that is adhered to the outer surface of the electrode assembly to prevent the electrode assembly from unwinding weakens its fixing force that prevents the electrode assembly from unwinding when the electrode assembly is immersed in an electrolyte, and the fixing force that prevents the electrode assembly from unwinding is released. As a result, the electrode assembly unwinds and the space between the battery case and the electrode assembly is filled, thereby preventing the electrode assembly from moving freely. In this case, the negative electrode is wound around the outermost surface of the electrode assembly, and when the electrode assembly is unwound, the negative electrode comes into contact with the inner surface of the battery case, thereby significantly reducing the battery resistance. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a secondary battery according to an embodiment of the present invention; [Diagram 2] 4 is a cross-sectional view illustrating an example of a state before an electrode assembly in a secondary battery according to an embodiment of the present invention is unwound; [Diagram 3] 4 is a cross-sectional view illustrating an example of an unwound state of an electrode assembly in a secondary battery according to an embodiment of the present invention; [Figure 4] 5 is a cross-sectional view illustrating an example of a state before an electrode assembly in a secondary battery according to another embodiment of the present invention is unwound; [Diagram 5]5 is a cross-sectional view illustrating an example of an unwound state of an electrode assembly in a secondary battery according to another embodiment of the present invention; [Figure 6] FIG. 4 is a perspective view showing a secondary battery according to still another embodiment of the present invention. [Figure 7] 11 is a cross-sectional view illustrating an example of an electrode assembly in a secondary battery according to still another embodiment of the present invention before it is unwound; FIG. [Figure 8] 1 is a photograph showing a state before the fixing tape in the secondary battery of the present invention reacts with the electrolyte. [Figure 9] 4 is a photograph showing a state in which the fixing tape in the secondary battery of the present invention has reacted with the electrolyte and been dissolved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The object, particular advantages, and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. In this specification, when referring to components in each drawing, it should be noted that the same components are numbered as much as possible when they are displayed in other drawings. In addition, the present invention may be realized in various different forms, and is not limited to the embodiments described herein. In addition, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

[0014] Secondary battery according to an embodiment Fig. 1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of an electrode assembly of a secondary battery according to an embodiment of the present invention before it is unwound, and Fig. 3 is a cross-sectional view of an electrode assembly of a secondary battery according to an embodiment of the present invention after it is unwound, in which the cap is removed in Figs. 2 and 3.

[0015] 1 to 3, a secondary battery 100 according to one embodiment of the present invention includes an electrode assembly 110 in which electrodes 113 and separators 114, 115 are alternately stacked and wound up, a battery case 120 in which the electrode assembly 110 and an electrolyte are contained, and a fixing tape 140 adhered to the outer surface of the electrode assembly 110.

[0016] Hereinafter, a secondary battery 100 according to one embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 3, the electrode assembly 110 is a power generating element capable of charging and discharging, and has a structure in which electrodes 113 and separators 114, 115 are assembled and alternately stacked. Here, the electrode assembly 110 may be formed in a form in which the electrodes 113 and the separators 114, 115 are assembled and wound up alternately. In this case, the electrode assembly 110 may be wound up into a cylindrical shape wound around a central axis C.

[0017] The electrodes 113 may include a positive electrode 112 and a negative electrode 111. Separators 114, 115 separate and electrically insulate the positive electrode 112 and the negative electrode 111.

[0018] The positive electrode 112 may include a positive electrode current collector 112a and a positive electrode active material 112b provided on one surface of the positive electrode current collector 112a. In this case, the positive electrode 112 may include a positive electrode uncoated portion which is a region where the positive electrode active material 112b is not laminated.

[0019] The positive electrode current collector 112a may be made of, for example, an aluminum foil. The positive electrode active material 112b may be lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing at least one of these.

[0020] The negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a. In this case, the negative electrode 111 may include a negative electrode uncoated portion which is a region where the negative electrode active material 111b is not laminated.

[0021] The negative electrode current collector 111a may be made of, for example, a copper foil (Foil) made of copper (Cu). The negative electrode active material 111b may be, for example, artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound, or an alloy thereof. In this case, the negative electrode active material 111b may further include, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

[0022] The negative electrode 111 is wound on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. In this case, the negative electrode current collector 111a of the negative electrode 111 is located on the outermost surface when the electrode assembly 110 is wound, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. This can reduce the battery resistance. That is, when the negative electrode tab 132 alone comes into contact with the inner surface of the battery case 120, a lot of resistance is applied to the negative electrode tab 132, which causes problems such as high heat generation and melting or disconnection of the negative electrode tab 132. In contrast, in the present invention, the negative electrode current collector 111a is located on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound, thereby significantly reducing the resistance.

[0023] The separators 114 and 115 are made of an insulating material and can provide insulation between the positive electrode 112 and the negative electrode 111 . Separators 114, 115 may also be, for example, a multilayer film made of microporous polyethylene, polypropylene, or a combination thereof, or a polymer film for a solid polymer electrolyte or a gel-type polymer electrolyte, such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride-hexafluoropropylene copolymer.

[0024] The battery case 120 may have an accommodation portion 121a that is open at an upper portion and accommodates the electrode assembly 110. In this case, the battery case 120 may be formed in, for example, a cylindrical shape.

[0025] In addition, the battery case 120 may have a receiving portion 121a with an open top, in which the electrode assembly 110 and the electrolyte are received. In this case, the secondary battery 100 according to an embodiment of the present invention may include a top cap 160 that covers an upper portion of the battery case 120.

[0026] Here, the inner surface of the battery case 120 may include a metal material. The battery case 120 is connected to the negative electrode 111 of the electrode assembly 110 to form the negative electrode 111, and the top cap 160 is connected to the positive electrode 112 of the electrode assembly 110 to form the positive electrode 112, and the battery case 120 and the top cap 160 may be insulated from each other.

[0027] Meanwhile, an insulating layer may be provided between the bottom surface of the battery case 120 and the lower part of the electrode assembly 110 to insulate the electrode assembly 110 from the battery case 120. In this case, the negative electrode tab 132 connected to the negative electrode 111 of the electrode assembly 110 may penetrate the insulating layer and come into contact with the bottom surface of the battery case 120.

[0028] The electrode tab 130 is attached to and electrically connected to the electrode 113 . The electrode tabs 130 may include a positive electrode tab 131 attached to the positive electrode 112 and a negative electrode tab 132 attached to the negative electrode 111 .

[0029] Meanwhile, referring to FIG. 1, the positive electrode tab 131 may be formed in the direction in which the cap (top cap 160) is located, which is the upper direction, and the negative electrode tab 132 may be located in the lower direction, toward the bottom surface of the receiving portion 121a of the battery case 120.

[0030] The electrolyte may include a salt, a solvent, and an additive. The salt may include a lithium salt, such as LiCl, LiBr, LiI, or LiClO. 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , C.H. 3 SO 3 Li, C.F. 3 SO 3 Li, (CF 3 SO 2 ) 2 The lithium tetraphenylborate may include at least one of NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate, imide, LiTFSI, LiFSI, and LiBOB.

[0031] The solvent may include at least one of aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate.

[0032] Additives include VC (vinylene carbonate), FB (fluorobenzene), FEC (fluoroethylene carbonate), PS (propane sultone), Esa (ethylene sulfite), and LiBF 4 It may include at least one of the above.

[0033] The fixing tape 140 is attached to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. When the fixing tape 140 is immersed in the electrolyte, the fixing force suppressing the unwinding of the electrode assembly 110 is weakened, and the electrode assembly 110 is unwound, filling the space between the battery case 120 and the electrode assembly 110. At this time, the fixing tape 140 includes a reactive material that reacts with the electrolyte and dissolves, and the reactive material is dissolved when the electrolyte is received, and the fixing force suppressing the unwinding is released. As a result, the electrode assembly 110 is unwound, filling the space E between the battery case 120 and the electrode assembly 110, and preventing the electrode assembly 110 from moving freely. At this time, the gap between the winding center I and the unwinding portion O of the electrode assembly 110 may become wider as the electrode assembly 110 is unwound.

[0034] The reactant may be at least one of oriented polystyrene (OPS), thermo plastic polyurethane (TPU), and general purpose polystyrene (GPPS), which reacts with and dissolves in the electrolyte.

[0035] The fixing tape 140 may include a base film 141 and an adhesive layer 142 provided on one surface of the base film 141 . The adhesive layer 142 includes a reactive material, and is dissolved when an electrolyte is contained in the battery case containing the electrode assembly 110, thereby eliminating the adhesive force. As a result, the prevention of the electrode assembly 110 from being unwound by the fixing tape 140 can be released.

[0036] Meanwhile, for example, the fixing tape 140 may be attached to the upper and lower parts of the outer circumferential surface of the electrode assembly 110. Here, the fixing tape 140 may be attached along the width direction of the electrode assembly 110. In this case, the fixing tape 140 may be attached to the winding end of the electrode assembly 110 and the periphery of the winding end on the outer circumferential surface of the electrode assembly 110, or may be attached around the periphery of the outer circumferential surface.

[0037] As another example, the fixing tape 140 may be attached to the upper and lower parts of the outer circumferential surface of the electrode assembly 110. Here, the fixing tape 140 may be attached along the length direction of the electrode assembly 110. In this case, the fixing tape 140 may be formed in a rectangular shape and attached to the winding end of the electrode assembly 110 and the periphery of the winding end.

[0038] In the secondary battery 100 according to an embodiment of the present invention configured as described above, the fixing tape 140, which is attached to the outer surface of the electrode assembly 110 to prevent unwinding, contains a reactive material that reacts with and dissolves in the electrolyte. As a result, when the electrolyte is received, the reactive material is dissolved and the fixing force that prevents unwinding is released, causing the electrode assembly 110 to unwind, filling the space E between the battery case 120 and the electrode assembly 110 and preventing the electrode assembly 110 from moving freely.

[0039] In this case, the negative electrode 111 is wound around the outermost surface of the electrode assembly 110, and when the electrode assembly 110 is unwound, the negative electrode 111 can come into contact with the inner surface of the battery case 120. This can significantly reduce the battery resistance.

[0040] Secondary battery according to another embodiment Secondary batteries according to other embodiments will now be described. Fig. 4 is a cross-sectional view illustrating an example of an electrode assembly in a secondary battery according to another embodiment of the present invention before it is unwound, and Fig. 5 is a cross-sectional view illustrating an example of an electrode assembly in a secondary battery according to another embodiment of the present invention after it is unwound, where the cap is removed in Figs. 4 and 5.

[0041] 4 and 5, a secondary battery according to another embodiment of the present invention includes an electrode assembly 110 in which electrodes 113 and separators 114, 115 are alternately stacked and wound up, a battery case 120 in which the electrode assembly 110 and an electrolyte are contained, and a fixing tape 240 adhered to the outer surface of the electrode assembly 110.

[0042] The secondary battery 200 according to the second embodiment of the present invention is different from the secondary battery according to the above-described embodiment in the location of the reactant in the fixing tape 240. Therefore, the present embodiment will be described focusing on the differences and omitting or briefly describing the overlapping content with the first embodiment.

[0043] More specifically, the electrode assembly 110 is a power generating element capable of charging and discharging, and has a structure in which electrodes 113 and separators 114, 115 are assembled and alternately stacked. Here, the electrode assembly 110 may be formed in a form in which the electrodes 113 and the separators 114, 115 are assembled and wound up alternately. In this case, the electrode assembly 110 may be wound up in a cylindrical shape around a central axis C.

[0044] The electrodes 113 may include a positive electrode 112 and a negative electrode 111. Separators 114, 115 separate and electrically insulate the positive electrode 112 and the negative electrode 111.

[0045] The positive electrode 112 may include a positive electrode current collector 112a and a positive electrode active material 112b provided on one surface of the positive electrode current collector 112a. In this case, the positive electrode 112 may include a positive electrode uncoated portion which is a region where the positive electrode active material 112b is not laminated.

[0046] The negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a. In this case, the negative electrode 111 may include a negative electrode uncoated portion which is a region where the negative electrode active material 111b is not laminated. The negative electrode current collector 111a may be made of, for example, a copper foil (Foil) made of copper (Cu).

[0047] The negative electrode 111 is wound on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. In this case, the negative electrode current collector 111a of the negative electrode 111 is located on the outermost surface when the electrode assembly 110 is wound, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. This can reduce the battery resistance. That is, when the negative electrode tab 132 alone comes into contact with the inner surface of the battery case 120, a lot of resistance is applied to the negative electrode tab 132, which causes problems such as high heat generation and melting or disconnection of the negative electrode tab 132. In contrast, in the present invention, the negative electrode current collector 111a is located on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound, thereby significantly reducing the resistance. The separators 114 and 115 are made of an insulating material and can provide insulation between the positive electrode 112 and the negative electrode 111 .

[0048] The battery case 120 may have a receiving portion that is open at an upper portion thereof and receives the electrode assembly 110. In this case, the battery case 120 may be formed in, for example, a cylindrical shape.

[0049] In addition, the battery case 120 may be formed with a receiving portion 121a having an open top, in which the electrode assembly 110 and the electrolyte are received. In this regard, the secondary battery 200 according to another embodiment of the present invention may include a top cap that covers the top of the battery case 120. Here, the inner surface of the battery case 120 may include a metal material.

[0050] The battery case 120 is connected to the negative electrode 111 of the electrode assembly 110 to form the negative electrode 111, and the top cap 160 is connected to the positive electrode 112 of the electrode assembly 110 to form the positive electrode 112, and the battery case 120 and the top cap 160 may be insulated from each other.

[0051] Meanwhile, an insulating layer may be provided between the bottom surface of the battery case 120 and the lower part of the electrode assembly 110 to insulate the electrode assembly 110 from the battery case 120. In this case, the negative electrode tab 132 connected to the negative electrode 111 of the electrode assembly 110 may penetrate the insulating layer and come into contact with the bottom surface of the battery case 120.

[0052] The electrode tab 130 is attached to and electrically connected to the electrode 113 . The electrode tabs 130 may include a positive electrode tab 131 attached to the positive electrode 112 and a negative electrode tab 132 attached to the negative electrode 111 .

[0053] The fixing tape 240 is attached to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. When the fixing tape 240 is immersed in the electrolyte, the fixing force that suppresses the unwinding of the electrode assembly 110 is weakened, and the electrode assembly 110 is unwound, filling the space between the battery case 120 and the electrode assembly 110. In this case, the fixing tape 240 includes a reactive material that reacts with the electrolyte and dissolves, and the reactive material is dissolved when the electrolyte is received, and the fixing force that suppresses the unwinding is released. As a result, the electrode assembly 110 is unwound, filling the space E between the battery case 120 and the electrode assembly 110, and preventing the electrode assembly 110 from moving freely.

[0054] Here, the reactant may be at least one of OPS (oriented polystyrene), TPU (thermo plastic polyurethane), and GPPS (general purpose polystyrene), which reacts with the electrolyte and dissolves.

[0055] The fixing tape 240 may include a base film 241 and an adhesive layer 242 provided on one surface of the base film 241 . The base film 241 contains a reactive material and is dissolved when the electrolyte is received, thereby removing the restriction on the unwinding of the electrode assembly 110 via the fixing tape 240. Meanwhile, the fixing tape 240 may be attached to the upper and lower parts of the outer periphery of the electrode assembly 110 .

[0056] Secondary battery according to another embodiment Hereinafter, a secondary battery according to another embodiment will be described. FIG. 6 is a perspective view showing a secondary battery according to still another embodiment of the present invention, and FIG. 7 is a cross-sectional view showing an example of a state before an electrode assembly in a secondary battery according to still another embodiment of the present invention is unwound.

[0057] 6 and 7, a secondary battery 300 according to another embodiment of the present invention includes an electrode assembly 110 in which electrodes 113 and separators 114, 115 are alternately stacked and wound up, a battery case 120 in which the electrode assembly 110 and an electrolyte are contained, and a fixing tape 340 adhered to the outer surface of the electrode assembly 110.

[0058] The secondary battery 300 according to the further embodiment of the present invention is different from the secondary batteries according to the above-described one and other embodiments in the configuration of the fixing tape 340. Therefore, in this embodiment, the overlapping content with the one and other embodiments will be omitted or briefly described, and the description will focus on the differences.

[0059] More specifically, the electrode assembly 110 is a power generating element capable of charging and discharging, and has a structure in which electrodes 113 and separators 114, 115 are assembled and alternately stacked. Here, the electrode assembly 110 may be formed in a form in which the electrodes 113 and the separators 114, 115 are assembled and wound up alternately. In this case, the electrode assembly 110 may be wound up in a cylindrical shape around a central axis C.

[0060] The electrodes 113 may include a positive electrode 112 and a negative electrode 111. Separators 114, 115 separate and electrically insulate the positive electrode 112 and the negative electrode 111.

[0061] The positive electrode 112 may include a positive electrode current collector 112a and a positive electrode active material 112b provided on one surface of the positive electrode current collector 112a. In this case, the positive electrode 112 may include a positive electrode uncoated portion which is a region where the positive electrode active material 112b is not laminated.

[0062] The negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a. In this case, the negative electrode 111 may include a negative electrode uncoated portion which is a region where the negative electrode active material 111b is not laminated. The negative electrode current collector 111a may be made of, for example, a copper foil (Foil) made of copper (Cu).

[0063] The negative electrode 111 is wound on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. In this case, the negative electrode current collector 111a of the negative electrode 111 is located on the outermost surface when the electrode assembly 110 is wound, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound. This can reduce the battery resistance. That is, when the negative electrode tab 132 alone comes into contact with the inner surface of the battery case 120, a lot of resistance is applied to the negative electrode tab 132, which causes problems such as high heat generation and melting or disconnection of the negative electrode tab 132. In contrast, in the present invention, the negative electrode current collector 111a is located on the outermost surface of the electrode assembly 110, and can come into contact with the inner surface of the battery case 120 when the electrode assembly 110 is unwound, thereby significantly reducing the resistance. The separators 114 and 115 are made of an insulating material and can insulate between the positive electrode 112 and the negative electrode 111.

[0064] The battery case 120 may have a receiving portion that is open at an upper portion thereof and receives the electrode assembly 110. In this case, the battery case 120 may be formed in, for example, a cylindrical shape.

[0065] In addition, the battery case 120 may be formed with a receiving portion 121a having an open top, in which the electrode assembly 110 and the electrolyte are received. In this regard, the secondary battery 300 according to still another embodiment of the present invention may include a top cap 160 covering an upper portion of the battery case 120. Here, the inner surface of the battery case 120 may include a metal material.

[0066] The battery case 120 is connected to the negative electrode 111 of the electrode assembly 110 to form the negative electrode 111, and the top cap 160 is connected to the positive electrode 112 of the electrode assembly 110 to form the positive electrode 112, and the battery case 120 and the top cap 160 may be insulated from each other.

[0067] Meanwhile, an insulating layer may be provided between the bottom surface of the battery case 120 and the lower part of the electrode assembly 110 to insulate the electrode assembly 110 from the battery case 120. In this case, the negative electrode tab 132 connected to the negative electrode 111 of the electrode assembly 110 may penetrate the insulating layer and come into contact with the bottom surface of the battery case 120.

[0068] The electrode tab 130 is attached to and electrically connected to the electrode 113 . The electrode tabs 130 may include a positive electrode tab 131 attached to the positive electrode 112 and a negative electrode tab 132 attached to the negative electrode 111 .

[0069] The fixing tape 340 is attached to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. The fixing tape 340 weakens the fixing force that prevents the electrode assembly 110 from unwinding when immersed in the electrolyte, and as the electrode assembly 110 unwinds, the space between the battery case 120 and the electrode assembly 110 is filled, thereby preventing the electrode assembly 110 from moving freely.

[0070] Meanwhile, as an example, when the fixing tape 340 is impregnated with an electrolyte, the electrolyte may penetrate between the fixing tape 340 and the electrode assembly 110, reducing the adhesion area and reducing the adhesive force. As another example, when the fixing tape 340 is impregnated with an electrolyte, the fixing tape 340 may expand and reduce the adhesive force. Meanwhile, when the electrode assembly 110 is charged in a state in which the fixing tape 340 is impregnated with an electrolyte and its adhesive force is weakened, the electrode assembly 110 may expand and the fixing force of the fixing tape 340 may be released more easily.

[0071] The fixing tape 340 may include a base film 341 and an adhesive layer 342 provided on one surface of the base film 341 . In addition, the adhesive layer 342 of the fixing tape 340 may have a low adhesive strength by using a low-tack adhesive. This allows the adhesive strength to be more effectively reduced when the electrode assembly 110 is immersed in an electrolyte, and makes it easier to release the fixing strength that prevents the electrode assembly 110 from unwinding.

[0072] Here, in the fixing tape 340, the adhesive layer 342 may be made of an acrylic adhesive, which is a low-tack adhesive, for example. In this case, the adhesive layer 342 may further contain a hardener to further reduce the adhesive strength.

[0073] Meanwhile, as another example, the adhesive strength of the fixing tape 340 may be reduced by reducing the thickness of the adhesive layer 342 so as to reduce the adhesive strength. In this case, for example, the thickness of the adhesive layer 342 may be reduced by 50% or more.

[0074] As another example, the fixing tape 340 may further include a hardener in the adhesive layer 342 so as to reduce adhesive strength. That is, the adhesive layer 342 may be hardened by the hardener, thereby reducing adhesive strength. In this case, the hardener may be, for example, isocyanate. Meanwhile, the fixing tape 340 may be adhered to the upper and lower parts of the outer circumferential surface of the electrode assembly 110, for example. Here, the fixing tape 340 may be adhered along the length direction of the electrode assembly 110. In this case, the fixing tape 340 may be formed in a rectangular shape and attached to the winding end of the electrode assembly 110 and the periphery of the winding end.

[0075] As another example, the fixing tape 340 may be attached to an upper portion and a lower portion of the outer circumferential surface of the electrode assembly 110. Here, the fixing tape 340 may be attached along the width direction of the electrode assembly 110.

[0076] Meanwhile, a battery pack may be configured by including a plurality of secondary batteries according to the one to other embodiments configured as described above.

[0077] A method for manufacturing a secondary battery according to an embodiment Hereinafter, a method for manufacturing a secondary battery according to one embodiment of the present invention will be described.

[0078] 1 to 3, a method for manufacturing a secondary battery according to one embodiment of the present invention includes a winding process of alternately stacking and winding electrodes 113 and separators 114 and 115 to form an electrode assembly 110, a tape adhering process of adhering a fixing tape 140 to the outer surface of the electrode assembly 110, and a housing process of housing the electrode assembly 110 and an electrolyte inside a battery case 120.

[0079] The manufacturing method of a secondary battery according to one embodiment of the present invention relates to a manufacturing method of a secondary battery for manufacturing the secondary battery according to the embodiment of the present invention described above. Therefore, in the embodiment of the method for manufacturing a secondary battery according to one embodiment of the present invention, the overlapping content with the secondary battery according to the above-mentioned one embodiment of the present invention will be omitted or briefly described, and the differences will be mainly described.

[0080] More specifically, the winding process may involve alternately stacking and winding the electrodes 113 and the separators 114 and 115 to form the electrode assembly 110. Here, the electrode 113 includes a positive electrode 112 and a negative electrode 111. In this case, the negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a.

[0081] In the winding process, the negative electrode 111 may be wound so as to be located on the outermost surface of the electrode assembly 110. More specifically, in the winding process, the negative electrode current collector 111a may be wound so as to be located on the outermost surface of the electrode assembly 110.

[0082] The tape adhering process may adhere the fixing tape 140 to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. In the tape adhesion process, a fixing tape 140 may be used that weakens the fixing force that prevents the electrode assembly 110 from unwinding when immersed in the electrolyte. In this case, in the tape adhesion process, a fixing tape 140 including a reactive material that reacts with the electrolyte and dissolves may be used. In the tape adhering process, the fixing tape 140 can be adhered to the upper and lower parts of the outer circumferential surface of the electrode assembly 110 .

[0083] In the housing process, the electrode assembly 110 and the electrolyte may be housed inside the battery case 120 . During the accommodation process, the reactant dissolves when the electrolyte is accommodated, and the fixing force of the fixing tape 140 that prevents the electrode assembly 110 from unwinding is released, allowing the electrode assembly 110 to unwind and fill the space between the battery case 120 and the electrode assembly 110.

[0084] In addition, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120 and the negative electrode 111 may come into contact with each other. In this case, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120, which includes a metal material, and the negative electrode current collector 111a may come into contact with each other.

[0085] Meanwhile, in the tape adhesion process, the electrode assembly 110 can be adhered using a fixing tape 140 including a base film 141 and an adhesive layer 142 including a reactive material and provided on one side of the base film 141. As a result, the adhesive layer 142 dissolves when the electrolyte is received during the receiving process, and the adhesive force disappears, allowing the electrode assembly 110 to be unwound.

[0086] Secondary battery manufacturing method according to another embodiment Hereinafter, a method for manufacturing a secondary battery according to another embodiment of the present invention will be described.

[0087] 4 and 5, a method for manufacturing a secondary battery according to another embodiment of the present invention includes a winding process of alternately stacking and winding electrodes 113 and separators 114 and 115 to form an electrode assembly 110, a tape adhering process of adhering a fixing tape 240 to the outer surface of the electrode assembly 110, and a housing process of housing the electrode assembly 110 and an electrolyte inside a battery case 120.

[0088] The method for manufacturing a secondary battery according to another embodiment of the present invention is different from the method for manufacturing a secondary battery according to the above-described embodiment of the present invention in that there is a difference in the location of the reactant in the fixing tape 240. Therefore, the present embodiment will be described mainly with respect to the differences and the overlapping contents with the above-described embodiment will be omitted or briefly described.

[0089] More specifically, the winding process may involve alternately stacking and winding the electrodes 113 and the separators 114 and 115 to form the electrode assembly 110. Here, the electrode 113 includes a positive electrode 112 and a negative electrode 111. In this case, the negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a.

[0090] In the winding process, the negative electrode 111 may be wound so as to be located on the outermost surface of the electrode assembly 110. More specifically, in the winding process, the negative electrode current collector 111a may be wound so as to be located on the outermost surface of the electrode assembly 110.

[0091] The tape adhering process may adhere the fixing tape 240 to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. In the tape adhesion process, a fixing tape 240 may be used that weakens the fixing force to prevent the electrode assembly 110 from unwinding when immersed in an electrolyte.

[0092] In this case, the fixing tape 240 may include a reactive material that reacts with the electrolyte and dissolves during the tape adhesion process. In the tape adhering process, the fixing tape 240 can be adhered to the upper and lower parts of the outer circumferential surface of the electrode assembly 110 .

[0093] In the housing process, the electrode assembly 110 and the electrolyte may be housed inside the battery case 120 . During the accommodation process, the reactant dissolves when the electrolyte is accommodated, and the fixing force of the fixing tape 240 that prevents the electrode assembly 110 from unwinding is released, allowing the electrode assembly 110 to unwind and fill the space between the battery case 120 and the electrode assembly 110.

[0094] In addition, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120 and the negative electrode 111 may come into contact with each other. In this case, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120, which includes a metal material, and the negative electrode current collector 111a may come into contact with each other.

[0095] Meanwhile, in the tape adhesion process, the electrode assembly 110 can be adhered using a fixing tape 240 including a base film 241 containing a reactive material and an adhesive layer 242 provided on one side of the base film 241. As a result, the base film 241 dissolves when the electrolyte is received during the receiving process, so that the electrode assembly 110 can be unwound.

[0096] Further, a method for manufacturing a secondary battery according to another embodiment Hereinafter, a method for manufacturing a secondary battery according to still another embodiment of the present invention will be described.

[0097] 6 and 7, a method for manufacturing a secondary battery according to another embodiment of the present invention includes a winding process of alternately stacking and winding electrodes 113 and separators 114 and 115 to form an electrode assembly 110, a tape adhering process of adhering a fixing tape 340 to an outer surface of the electrode assembly 110, and a housing process of housing the electrode assembly 110 and an electrolyte inside a battery case 120.

[0098] The method for manufacturing a secondary battery according to still another embodiment of the present invention is different from the methods for manufacturing a secondary battery according to the above-described embodiment and the other embodiments in the fixing tape 340. Therefore, the present embodiment will be described mainly with respect to the differences and the contents overlapping with the above-described embodiment will be omitted or briefly described.

[0099] More specifically, the winding process may involve alternately stacking and winding the electrodes 113 and the separators 114 and 115 to form the electrode assembly 110. Here, the electrode 113 includes a positive electrode 112 and a negative electrode 111. In this case, the negative electrode 111 may include a negative electrode current collector 111a and a negative electrode active material 111b provided on one surface of the negative electrode current collector 111a.

[0100] In the winding process, the negative electrode 111 may be wound so as to be located on the outermost surface of the electrode assembly 110. More specifically, in the winding process, the negative electrode current collector 111a may be wound so as to be located on the outermost surface of the electrode assembly 110.

[0101] The tape adhering process may adhere the fixing tape 340 to the outer surface of the electrode assembly 110 to prevent the electrode assembly 110 from unwinding. In the tape adhesion process, a fixing tape 340 may be used that weakens the fixing force to prevent the electrode assembly 110 from unwinding when immersed in an electrolyte. In the tape adhering process, the fixing tape 340 can be adhered to the upper and lower parts of the outer circumferential surface of the electrode assembly 110 .

[0102] In the housing process, the electrode assembly 110 and the electrolyte may be housed inside the battery case 120 . During the accommodation process, the fixing force of the fixing tape 340, which prevents the electrode assembly 110 from unwinding when the electrolyte is accommodated, weakens, allowing the electrode assembly 110 to unwind and fill the space between the battery case 120 and the electrode assembly 110.

[0103] In addition, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120 and the negative electrode 111 may come into contact with each other. In this case, when the electrode assembly 110 is unwound during the storage process, the inner surface of the battery case 120, which includes a metal material, and the negative electrode current collector 111a may come into contact with each other.

[0104] Meanwhile, the tape adhesion process may adhere to the electrode assembly 110 using a fixing tape 340 including a base film 341 and an adhesive layer 342 provided on one side of the base film 341. In the tape adhesion process, the adhesive layer 342 of the fixing tape 340 may be made of a low tack adhesive.

[0105] Here, the tape adhesion process may use, for example, a fixing tape 340 in which the adhesive layer 342 includes an acrylic adhesive, which is a low-tack adhesive. In this case, the tape adhesion process may further reduce the adhesive strength by further including a hardener in the adhesive layer 342.

[0106] Meanwhile, in another example of the tape adhesion process, the thickness of the adhesive layer 342 may be reduced to reduce the adhesive strength of the fixing tape 340. In this case, the thickness of the adhesive layer 342 may be reduced by, for example, 50% or more.

[0107] As another example of the tape adhesion process, the fixing tape 340 may further include a hardener in the adhesive layer 342 so as to reduce the adhesive strength. That is, the adhesive layer 342 may be hardened by the hardener, thereby reducing the adhesive strength. Here, the hardener may be, for example, isocyanate. The adhesive strength may be adjusted by adjusting the type and ratio of the hardener.

[0108] Meanwhile, in the tape adhering process, for example, the fixing tape 340 may be adhered to the upper and lower parts of the outer circumferential surface of the electrode assembly 110. Here, the fixing tape 340 may be adhered along the length direction of the electrode assembly 110. In this case, the fixing tape 340 may be formed in a rectangular shape and attached to the winding end of the electrode assembly 110 and the periphery of the winding end.

[0109] As another example, the tape adhering process may adhere the fixing tape 340 to the upper and lower parts of the outer circumferential surface of the electrode assembly 110. Here, the fixing tape 340 may be adhered along the width direction of the electrode assembly 110.

[0110] <Experimental Example> Fig. 8 is a photograph showing the state of the fixing tape in the secondary battery of the present invention before it reacts with the electrolyte, and Fig. 9 is a photograph showing the state of the fixing tape in the secondary battery of the present invention after it reacts with the electrolyte and dissolves. Here, Fig. 8 is a photograph showing the fixing tape immediately after it is immersed in the electrolyte, and Fig. 9 is a photograph showing the fixing tape 1 hour after it is immersed in the electrolyte.

[0111] 8 and 9, the fixing tape T applicable to the secondary battery of the present invention was immersed in an electrolyte solution, and a dissolution test for the fixing tape T was carried out. Here, as the solvent for the electrolyte, DMC (dimethyl carbonate), EMC (ethyl methyl carbonate), and EC (ethylene carbonate) were used. As the fixing tape T, a TPU (Thermo Plastic Polyurethane) tape was used.

[0112] 8 and 9, the electrode assembly is prevented from unwinding by using a fixing tape T containing a reactive material that reacts with the electrolyte and dissolves, and it can be seen that when the electrode assembly is placed in a battery case containing an electrolyte, the fixing tape T dissolves and the electrode assembly unwinds. As a result, it can be seen that the space between the battery case and the electrode assembly is filled as the electrode assembly unwinds, and that the outermost surface of the electrode assembly can come into contact with the inner surface of the battery case when the electrode assembly unwinds.

[0113] Although the present invention has been described in detail above with reference to specific embodiments, this is for the purpose of specifically explaining the present invention, and the present invention is not limited thereto. It is possible to carry out various embodiments within the technical concept of the present invention by those skilled in the art. Moreover, the specific scope of protection of the invention will become apparent from the appended claims. [Explanation of symbols]

[0114] 100, 200, 300: Secondary battery 110: Electrode assembly 111: Negative electrode 111a: Negative electrode current collector 111b: Negative electrode active material 112: Positive electrode 112a: Positive electrode current collector 112b: Positive electrode active material 113: Electrode 114, 115: Separator 120: Battery case 121a: Storage unit 130: Electrode tab 131: Positive electrode tab 132: Negative electrode tab 140, 240, 340: Fixed tape 141, 241, 341: Base film 142, 242, 342: Adhesive layer 160: Top cap C: Central axis I: Center of winding O: Winding removal section E: Space

Claims

1. an electrode assembly in which electrodes and separators are alternately stacked and wound; a battery case in which the electrode assembly and an electrolyte are contained; a fixing tape attached to an outer surface of the electrode assembly to prevent the electrode assembly from unwinding; Including, When the fixing tape is immersed in the electrolyte, a fixing force that suppresses the unwinding of the fixing tape is weakened, so that the electrode assembly unwinds and the space between the battery case and the electrode assembly is filled, The fixing tape is A base film; An adhesive layer provided on one surface of the base film, the base film includes a reactive material that reacts with the electrolyte and dissolves, and the base film is dissolved when the electrolyte is received, thereby releasing the inhibition of unwinding of the electrode assembly via the fixing tape; The adhesive layer includes a reactive material that reacts with the electrolyte and dissolves therein, and the reactive material is made of TPU (Thermo Plastic Polyurethane). Secondary battery.

2. The adhesive layer includes an acrylic adhesive that is a low tack adhesive, The secondary battery of claim 1 , wherein the electrode assembly is unwound when the electrode assembly is impregnated with the electrolyte and the adhesive strength of the electrode assembly is reduced.

3. The secondary battery according to claim 1 , wherein the adhesive layer further comprises a hardener to reduce adhesive strength.

4. The fixing tape is The secondary battery according to claim 1 , wherein the electrode assembly is adhered to an upper and lower portion on an outer circumferential surface thereof.

5. The fixing tape is The secondary battery according to claim 1 , wherein the adhesive is attached to the upper and lower parts of the outer circumferential surface of the electrode assembly, and the adhesive is attached to the winding end of the electrode assembly and to the periphery of the winding end.

6. The electrodes include a positive electrode and a negative electrode, the negative electrode is wound around the outermost surface of the electrode assembly; The secondary battery according to claim 1 , wherein the electrode assembly comes into contact with an inner surface of the battery case when unwound.

7. The negative electrode includes a negative electrode current collector and an active material provided on one surface of the negative electrode current collector, the negative electrode current collector is located at the outermost surface when the electrode assembly is wound and contacts the inner surface of the battery case when the electrode assembly is unwound; The secondary battery according to claim 6 , wherein the inner surface of the battery case includes a metal material.

8. a winding step of alternately stacking and winding the electrodes and the separators to form an electrode assembly; a tape adhering step of adhering a fixing tape to an outer surface of the electrode assembly to prevent the electrode assembly from unwinding; a step of housing the electrode assembly and the electrolyte in a battery case; Including, In the tape adhesion process, the fixing tape is used, the fixing force of which suppresses unwinding when impregnated with the electrolyte is weakened, The tape adhering process includes adhering the electrode assembly using the fixing tape, the fixing tape including a base film including a reactive material that reacts with the electrolyte and dissolves therein, and an adhesive layer provided on one side of the base film, During the accommodation process, when the electrolyte is accommodated, the base film is dissolved and the fixing strength of the fixing tape is weakened, so that the electrode assembly is unwound and the space between the battery case and the electrode assembly is filled, The adhesive layer includes a reactive material that reacts with the electrolyte and dissolves therein, and the reactive material is made of TPU (Thermo Plastic Polyurethane). A method for manufacturing a secondary battery.

9. The tape adhesion process includes: The method of claim 8 , wherein the fixing tape is attached to an upper and lower portion of an outer circumferential surface of the electrode assembly.

10. The tape adhesion process includes: The method of claim 8 , wherein the fixing tape is attached to the upper and lower parts of the outer circumferential surface of the electrode assembly, and is attached to the wound end of the electrode assembly and the periphery of the wound end.

11. The electrodes include a positive electrode and a negative electrode, The winding step is performed such that the negative electrode is positioned on the outermost surface of the electrode assembly. The method for manufacturing a secondary battery according to claim 8 , wherein when the electrode assembly is unwound during the accommodation process, the inner surface of the battery case and the negative electrode come into contact with each other.

12. The negative electrode includes a negative electrode current collector and an active material provided on one surface of the negative electrode current collector, The winding step includes winding the negative electrode current collector so that the negative electrode current collector is positioned on the outermost surface of the electrode assembly, The method of claim 11 , wherein when the electrode assembly is unwound during the accommodation process, the inner surface of the battery case, which includes a metal material, comes into contact with the negative electrode current collector.

13. The tape adhesion process includes adhering the electrode assembly using the fixing tape, the fixing tape including a base film and an adhesive layer provided on one side of the base film, the adhesive layer including a reactive material that reacts with the electrolyte and dissolves therein, The method of claim 8 , wherein the adhesive layer is dissolved during the accommodation of the electrolyte, thereby eliminating adhesive force and unwinding the electrode assembly.

14. The tape adhesion process includes adhering the electrode assembly to the fixing tape, the fixing tape including a base film and an adhesive layer including an acrylic adhesive, which is a low-tack adhesive, and provided on one side of the base film, and adhering the fixing tape to the electrode assembly; The method of claim 8 , wherein the electrode assembly is unwound by reducing an adhesive strength of the adhesive layer when the adhesive layer is immersed in the electrolyte during the accommodation process.

15. The tape adhesion process includes adhering the electrode assembly to the fixing tape, the fixing tape including a base film and an adhesive layer provided on one side of the base film, the adhesive layer including a hardener to reduce adhesive strength, and the fixing tape is attached to the electrode assembly. The method of claim 8 , wherein the electrode assembly is unwound by reducing an adhesive strength of the adhesive layer when the adhesive layer is immersed in the electrolyte during the accommodation process.

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