Secondary battery and manufacturing

Abstract

Having a secondary battery: a can element; and an electrode arrangement comprising a positive electrode, a negative electrode and a separator arranged between them, which are wound together in a jelly roll shape, where the positive electrode or the negative electrode has: an electrode collector; a coating section that is coated with an active material on the electrode collector; and a cut-in tab portion extending from the coating section in a lateral direction of the electrode collector that is perpendicular to a longitudinal direction of the electrode collector, wherein the cut-in tab portion is uncoated with the active material and overlaps, thereby forming two or more layers when the electrode is wound, wherein the incision flap portion is cut in such a way that it forms several incision flaps which are distributed in a circumferential direction around a central axis of the electrode arrangement when the electrode arrangement is wound, wherein the multiple incision tabs are bent in a radial direction towards the central axis, so that they overlap each other in an overlap area in order to be connected to the can element at the same time, wherein adjacent incision tabs of the multiple incision tabs are spaced apart in the circumferential direction in an area that is further away from the central axis in the radial direction than the overlap area.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] The present application claims priority over Korean patent applications No. 10-2017-0048645, filed on April 14, 2017, and 10-2018-0043191, filed on April 13, 2018, which are hereby incorporated by reference in their entirety. TECHNICAL AREA

[0002] The present invention relates to a secondary battery and its manufacture, and in particular to a secondary battery in which an electrode tab increases in its mechanical strength, and its manufacture. STATE OF THE ART

[0003] Batteries (cells) that generate electrical energy through physical or chemical reaction in order to supply the generated electrical energy to the outside are used when AC power to be supplied to the building is not obtained or DC power is required according to the living environments surrounded by various electrical and electronic devices.

[0004] Generally, primary and secondary batteries are used in this context. Both are chemical batteries that utilize chemical reactions. Primary batteries are depleted batteries, commonly known as dry cell batteries. Secondary batteries are rechargeable batteries that are produced using a material in a redox process involving an electric current and a substance, a process that can be repeated multiple times. When the reduction reaction occurs in the material due to the electric current, the battery is charged (power is supplied), and when the oxidation reaction occurs, the battery is discharged. This charging-discharging cycle is repeated to generate electricity.

[0005] A secondary lithium-ion battery is manufactured through the following processes. An active material is applied to a conductive foil of the positive electrode and a conductive foil of the negative electrode, respectively, to a predetermined thickness. A separator is placed between the conductive foil of the positive electrode and the conductive foil of the negative electrode. Then, an electrode assembly, in which the conductive foil of the positive electrode, the separator, and the conductive foil of the negative electrode are wound several times in a jelly roll or cylindrical shape, is enclosed in a cylindrical or prismatic container, pouch, or similar container to seal the resulting product, thus manufacturing a lithium-ion battery.

[0006] An electrode arrangement and a secondary battery containing such an arrangement, according to the prior art, is disclosed in Korean patent publication no. 10-2012-0006389.

[0007] In the secondary battery according to the state of the art, it is necessary to apply a technology in which a metal with low resistance is applied to a negative electrode tab or the number of electrode tabs is increased in order to develop a cell with low resistance.

[0008] A negative multi-tab structure developed by this necessity was a two-tab structure in which an electrode tab is attached to each of a core and an outer section, or a three-tab structure in which an electrode tab is attached to each of a core and an outer section, and a middle tab is attached to an intermediate section.

[0009] However, to attach the central tab to the properties of the Jellyroll, an uncoated section must be created at a predetermined point in the center of the electrode. This presents a problem: the battery capacity is reduced due to the increased size of the uncoated section. REVELATION OF THE INVENTIONAL PROBLEM

[0010] Against this background, the present invention was generated to solve the above-mentioned problem, and it is an object of the present invention to provide a secondary battery in which a multiple tab is formed while minimizing a non-coating section, and its manufacture.

[0011] Furthermore, it is an object of the present invention to provide a secondary battery that is able to increase its mechanical strength while cutting into an electrode foil to form an electrode tab, and to provide the manufacture thereof. TECHNICAL SOLUTION

[0012] A secondary battery according to an embodiment of the present invention comprises: an electrode having a coated section coated with an active material on an electrode collector and a non-coated section on which the active material is not applied to the electrode collector in a longitudinal direction of the electrode collector; and a slotted tab portion extending from the coated section in a lateral direction of the electrode collector without coating with the active material and overlapping each other, thereby forming two or more layers when the electrode is wound.

[0013] The notched tab section can extend continuously from 1 / 3 or more of the total length of the coating section.

[0014] In a state where the electrode is wound, the notch tab portion can be cut, thereby forming multiple notch tabs.

[0015] The notch tab can have a width of 4 mm to 5 mm.

[0016] The electrode can be contained within a can element, and the notched tab can be bent to connect to the can element.

[0017] A curved part, formed by bending the notch tab, can be connected to the can element.

[0018] The secondary battery may also contain an insulating element located between the curved part and one end of the electrode.

[0019] The secondary battery may also contain an electrode tab attached to the non-coated section.

[0020] In the state in which the electrode is wound, the notch tab portion can be cut to form multiple notch tabs, and the electrode can be received in a can element, and the multiple notch tabs can be bent to overlap the electrode tab.

[0021] The electrode tab and the multiple incision tabs that overlap and are connected to the electrode tab can be connected together with the can element.

[0022] Each of the multiple incision tabs can have a incision length of 8 mm to 11 mm.

[0023] Each of the multiple incision tabs can have a incision length of 9 mm to 10 mm.

[0024] The electrode can be a negative electrode.

[0025] A method for manufacturing a secondary battery may comprise: a preparation step of preparing an electrode that is provided with a coated section coated with an active material on an electrode collector and a non-coated section on which the active material is not applied to the electrode collector in a longitudinal direction of the electrode collector; a cut-flap section formation step of cutting the electrode to form a cut-flap section that extends without coating with the active material in a transverse direction of the electrode collector over an area of ​​the electrode which corresponds to 1 / 3 or more of the total length of the coated section;a winding step of stacking the electrode on which the notch tab portion is formed, on a separator, and the other electrode with a polarity different from that of the electrode, and winding the stack to form an electrode assembly; a notch tab formation step of cutting the notch tab portion in the electrode assembly to form multiple notch tabs; and an installation step of receiving the electrode assembly in a can element to connect each of the notch tabs to the can element.

[0026] In the preparation step, the negative electrode can be prepared.

[0027] In the preparation step, the coating section, which is coated with the active material on the electrode collector, and the non-coating section, on which the active material is not applied, can be arranged parallel to each other in the width direction of the electrode collector.

[0028] In the cut tab formation step, the cut tab part, on which the active material is not applied, can be cut in the width direction of the coating section, while the coating section and the non-coating section, which are arranged parallel to each other, are cut in the longitudinal direction of the electrode collector.

[0029] In the incision tab formation step, the incision can be carried out in such a way that the incision tab part, on which the active material is not applied, is incised in the width direction of the coating section when the electrode is cut.

[0030] In the incision tab formation step, the incision tab part can be cut using a laser.

[0031] During the installation step, the electrode arrangement can be inserted into the can element in a state where the slot tab is bent to connect the bent section of the slot tab to the can element.

[0032] During the installation step, the curved section of the cut tab can be welded to connect it to the can element.

[0033] During the installation step, the curved sections of the multiple cut tabs can overlap each other in order to be connected to the can element simultaneously.

[0034] During the wrapping step, the cut tab part can overlap to form two or more layers. BENEFICIAL EFFECTS

[0035] According to the present invention, the multiple flap can be formed while minimizing the formation of the non-coating section.

[0036] According to the present invention, the multiple tab can be formed to minimize electrical resistance.

[0037] According to the present invention, the formation of the non-coating area can be minimized in order to secure the battery capacity.

[0038] According to the present invention, the incision flaps can overlap to form two or more layers, while the incision flap, which is the foil flap, is formed from the electrode foil, thereby increasing the mechanical strength.

[0039] According to the present invention, the slit tab, which is the foil tab, can increase in its mechanical strength to prevent the slit tab from breaking in the bent state, and thus the slit tab can be applied to the can element in the bent state to ensure the reliability of the electrical connection and improve the bond performance.

[0040] According to the present invention, the cut tab and the electrode tab can be connected to the can element simultaneously to ensure weldability.

[0041] According to the present invention, the multiple notch tabs can be formed outside the electrode arrangement in order to install the insulating element between the multiple notch tabs and the end of the electrode arrangement, thereby preventing the notch tabs and the electrode arrangement from coming into contact with each other, thus improving safety. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a developmental view of an electrode according to an embodiment of the present invention. Fig. Figure 2 is a perspective view illustrating a state in which the electrode of Fig. 1 is wrapped. Fig. 3 is a perspective view illustrating a state in which a notch flap portion has been cut to form a notch flap in Fig. 2 to form. Fig. Figure 4 is a perspective projection view when viewed through a can element in a state in which an electrode arrangement is installed in the can element according to an embodiment of the present invention. Fig. 5 is a bottom view of only the electrode arrangement in Fig. 4. Fig. Figure 6 is a flowchart that illustrates a process for manufacturing a secondary battery step by step. Fig. Figure 7 is a top view illustrating a condition in which a coating section and a non-coating section formed in a longitudinal direction of an electrode collector are arranged parallel to each other in a lateral direction of the electrode collector according to an embodiment of the present invention. Fig. Figure 8 is a bottom view illustrating a state in which a cut tab and an electrode tab are connected to each other according to another embodiment of the present invention. Fig. 9 is a side view of Fig. 8. METHODS OF IMPLEMENTATION

[0042] A secondary battery and its manufacture according to exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] Terms or words used in the description and claims should not be interpreted as having a limited lexical meaning and should be understood as suitable terms chosen by the inventor, based on his / her ability to define terms to describe his / her invention in the best way that can be seen by others. Therefore, embodiments and drawings described herein are merely exemplary and not exhaustive, and it is understood that various equivalents may be used in place of the embodiments.

[0044] In the drawings, the dimensions of each component or specific section forming the component have been exaggerated, omitted, or schematically illustrated for the sake of clarity and to simplify the description. Thus, the dimensions of each element do not fully reflect their actual size. Furthermore, detailed descriptions relating to known functions or configurations are excluded to avoid unnecessarily obscuring aspects of the present invention.

[0045] Fig. Figure 1 is a developmental view of an electrode according to an embodiment of the present invention and Fig. Figure 2 is a perspective view illustrating a state in which the electrode of Fig. 1 is wrapped.

[0046] As in the Fig. 1 and Fig. As illustrated in Figure 2, a secondary battery according to an embodiment of the present invention comprises an electrode on which a coated section 110, which is coated with an active material a on an electrode collector, and a non-coated section 120, on which the active material a is not applied to the electrode collector, are arranged in a longitudinal direction of the electrode collector, and a slotted tab portion 111, which extends from the coated section 110 in a lateral direction of the electrode collector without coating with the active material a and overlaps each other, thereby forming two or more layers when the electrode 100 is wound ( Fig. Figure 2 illustrates a cut tab part 111 that overlaps and thus forms two or more layers).

[0047] The foil flaps can overlap to form two or more layers, while the cut-in flap part, which is a foil flap, is formed from the electrode foil of the electrode collector, thereby increasing the mechanical strength.

[0048] Electrode 100 can be a positive electrode coated with an active material of the positive electrode, or a negative electrode coated with an active material of the negative electrode. Electrode assembly 1 can be produced by stacking the positive electrode, the negative electrode, and a separator multiple times, such that the separator is positioned between the positive and negative electrodes.

[0049] The electrode arrangement 1 can further be produced by winding a stack in which the positive electrode, the separator and the negative electrode are stacked in a jelly roll shape.

[0050] The positive electrode can be an aluminum electrode collector and may include a coated section of the positive electrode that is coated with the active material of the positive electrode, and a non-coated section of the positive electrode that is not coated with the active material of the positive electrode.

[0051] The active material of the positive electrode can contain a lithium-containing transition metal oxide such as LiCoO2, LiNiO2, LiMnO2 and LiMnO4 or a lithium chalcogenide compound.

[0052] The coating section of the positive electrode can be produced, for example, by applying the active material of the positive electrode to a section of at least one surface of the aluminum electrode collector, and the remaining section of the aluminum electrode collector that is not coated with the active material of the positive electrode can be the non-coating section of the positive electrode.

[0053] The negative electrode can be a copper electrode collector and may include a coated section of the negative electrode that is coated with the active material of the negative electrode, and a non-coated section of the negative electrode that is not coated with the active material of the negative electrode.

[0054] The active material of the negative electrode can be a carbon material such as crystalline carbon, amorphous carbon, a carbon composite and carbon fiber, a lithium metal or a lithium alloy.

[0055] The coating section of the negative electrode can be produced, for example, by applying the active material of the negative electrode to a section of at least one surface of the copper electrode collector, and the remaining section of the copper electrode collector that is not coated with the active material of the negative electrode can be the non-coating section of the negative electrode.

[0056] The separator can be produced by applying a polyvinylidene fluoride hexafluoropropylene copolymer (PVDF-HFP copolymer) to a base material selected from the group consisting, for example, of polyethylene (PE), polystyrene (PS), polypropylene (PP) and a copolymer of polyethylene (PE) and polypropylene.

[0057] As described above, the electrode 100 according to the present invention can be one of the positive and negative electrodes that form the electrode arrangement 1. In particular, the electrode 100 can be one that requires a further reduction of the resistance of the positive and negative electrodes.

[0058] In the present invention, the negative electrode is described as an example.

[0059] The electrode 100 has an end where the uncoated section 120 is formed. An electrode tab 121 can be attached to the uncoated section 120 formed at one end of the electrode 100.

[0060] The cut-in tab section 111 can be formed by cutting the electrode 100 to extend from the coating section 110 of the electrode 100 in the width direction. Only the electrode collector can be formed to extend over an area corresponding to 1 / 3 or more of the total length of the coating section 110 of the electrode 100, and the active material a cannot be applied.

[0061] Only the active material a can be removed from the coating section 110 extending from the electrode 100 to form the notch tab part 111. Alternatively, only the electrode foil can extend without applying the active material a to the surface of the coating section 110 of the electrode 100 to form the notch tab part 111.

[0062] Thus, there can be an effect of forming multiple flaps while minimizing the formation of the non-coating section, and the formation of the non-coating section can be minimized to ensure battery capacity.

[0063] Fig. Figure 3 is a perspective view illustrating a state in which the notch flap portion has been cut to form the notch flap in Fig. 2 to form.

[0064] As in Fig. As illustrated in Figure 3, the notch tab portion 111 can be cut in the wound state to form multiple notch tabs 111a. As the number of notch tabs 111a increases, the electrode tab resistance can decrease.

[0065] Here, a notch tab 111a can have a width of 4 mm to 5 mm. This is done for the reason that if the notch tab 111a has a width of less than 4 mm, the mechanical strength may be weakened, and if the notch tab 111a has a width exceeding 5 mm, deformation during the bonding process for the electrical connection with the can element may be difficult.

[0066] The slit tab 111a, which is the foil tab, can increase in its mechanical strength to prevent the slit tab 111a from breaking in the bent state, and thus the slit tab 111a can be applied to the can element in the bent state to ensure the reliability of the electrical connection and improve the bond performance.

[0067] Fig. Figure 4 is a perspective projection view when viewed through the can element in a state in which the electrode arrangement is installed in the can element according to an embodiment of the present invention, and Fig. 5 is a bottom view of only the electrode arrangement in Fig. 4.

[0068] As in Fig. 4 and Fig. As illustrated in Figure 5, in the electrode arrangement 1 of the secondary battery according to the present invention, a bent part of the slotted tab 111a can be welded to be coupled to the can element 10, so that the slotted tab 111a is electrically connected to the can element 10 in a state in which the slotted tab 111a is bent while it is received in the can element 10.

[0069] The notch tab 111a can be bent to allow one end of the notch tab 111a to couple with the center of a bottom surface of the can element 10. Thus, the multiple notch tabs 111a can be electrically connected to each other, while the electrical connection is smooth to minimize electrical resistance.

[0070] Fig. Figure 8 is a bottom view illustrating a state in which a cut tab and an electrode tab are connected to each other according to another embodiment of the present invention, and Fig. 9 is a side view of Fig. 8.

[0071] As in Fig. 8 and Fig. As illustrated in Figure 9, in a secondary battery according to another embodiment of the present invention, a notched tab portion 111 of an electrode arrangement 1 in which an electrode 100 is wound can be cut, thereby forming several notched tabs 111a. The several notched tabs 111a can be bent and then joined to overlap an electrode tab 121 formed at a central section of one end of the electrode arrangement 1.

[0072] Furthermore, the electrode arrangement 1 can be incorporated into a can element 10 and the multiple cut tabs 111a, which are connected to overlap the electrode tab 121, can be joined together with the electrode tab 121 by welding to the can element 10.

[0073] As described above, in the secondary battery according to another embodiment of the present invention, since the several cut tabs 111a and the electrode tab 121 together with the can element 10 are welded in the state in which the cut tabs 111a and the electrode tab 121 are connected to overlap each other, weldability can be easily ensured.

[0074] In the secondary battery according to another embodiment of the present invention, if one end of the electrode assembly 1 has a length in the range of 16 mm to 21 mm, the notch length of each of the several notch tabs 111a can be in the range of 8 mm to 11 mm. If the notch length of the notch tab 111a is less than 8 mm, the length of the notch tab 111a can be shortened and the notch tab 111a can be bent. Thus, it can be difficult to allow the notch tab 111a to overlap the electrode tab 121 formed at a central section of one end of the electrode assembly 1. Furthermore, if the cut length of the cut tab 111a exceeds 11 mm, the length of the cut tab 111a may be unnecessarily extended, increasing costs due to material waste and the space occupied by the cut tab 111a within the can element 10.Thus, the amount of electrolyte filled into the can element 10 can be reduced, thereby decreasing its capacity. Preferably, the notch tab 111a can have a notch length of 9 mm to 10 mm.

[0075] In the secondary battery according to another embodiment of the present invention, an insulating element 130 can be formed between a bent part of the notched tab 111a and an end of the electrode arrangement 1 in which the electrode 100 is wound.

[0076] The insulating element 130 can insulate the notch tab 111a from the end of the electrode arrangement 1 to prevent the notch tab 111a from coming into contact with the electrode arrangement 1.

[0077] The multiple notch tabs 111a can be formed on an outer section of the end of the electrode arrangement to prevent the insulating element 130 from interfering with the end of the electrode arrangement 1.

[0078] The multiple notched tabs 111a can be formed on the outside of the electrode assembly, so that the insulating element 130 is installed between the multiple notched tabs 111a and the end of the electrode assembly 1. This prevents contact between the notched tab 111a and the electrode assembly 1, thus improving safety.

[0079] The following describes in detail a method for manufacturing a secondary battery with reference to the attached drawings.

[0080] Fig. Figure 6 is a flowchart that illustrates a process for manufacturing a secondary battery step by step.

[0081] As in Fig. Figure 6 illustrates that a process for manufacturing a secondary battery comprises a preparation step (S1), a notch tab formation step (S2), a winding step (S3), a notch tab formation step (S4) and an installation step (S5).

[0082] The preparation step (S1) is a step of preparing an electrode 100 in which a coating section 110, which is coated with an active material a on an electrode collector, and a non-coating section 120, on which the active material a is not applied, are provided in a longitudinal direction of the electrode collector.

[0083] Here, electrode 100 can be a negative electrode.

[0084] Fig. Figure 7 is a top view illustrating a condition in which the coating section and the non-coating section formed in the longitudinal direction of the electrode collector are arranged parallel to each other in a lateral direction of the electrode collector according to an embodiment of the present invention.

[0085] As in Fig. As illustrated in Figure 7, in the preparation step (S1) the coating section 110 and the non-coating section 120, which are formed in a longitudinal direction L of the electrode collector, can be arranged parallel to each other in the width direction W of the electrode collector.

[0086] In the incision flap formation step (S2) is a step of incising the electrode 10 to form an incision flap part 111 which extends in a state in which the active material is not formed in the width direction W of the coating section 111 on an area of ​​the electrode 100 which corresponds to 1 / 3 or more of a length of the coating section 110.

[0087] As described above, the cutting of the cut tab part 111 in the electrode 100 can include a step of cutting a section of the non-coating section on which the active material a is not applied and which is formed in the width direction W of the coating section 11, while the electrode 100 is cut in the electrode collector to form a cut tab part 11.

[0088] If the coating section 100 and the non-coating section 120, which are formed in the longitudinal direction L of the electrode collector, are arranged parallel to each other in the lateral direction W of the electrode collector, the non-coating section, on which the active material is not applied and which is formed between one coating section 110 and the other coating section 110a, which are arranged parallel to each other in the lateral direction W, can be cut, while the coating section 110 and the non-coating section 120, which are arranged parallel to each other, are cut to form the cut tab part 111 in the lateral direction W of the coating section 110.

[0089] The winding step (S3) can be a step of stacking the electrode 100, on which the notched tab part 111 is formed, on the separator and the other electrode with a polarity different from that of the electrode 100, and winding the stack to form the electrode arrangement 1.

[0090] While the electrode 100 is wound, the notched tab part 111 can overlap to form two or more layers.

[0091] The incision flap formation step (S4) can be a step of cutting the incision flap part 111 to form several incision flaps 111a.

[0092] The incision tabs 111a, which are formed by cutting the incision tab part 111, can overlap each other to form two or more layers like the incision tab part 111.

[0093] In this process, the cutting of the incision tab part 111 using a laser can be maximized in terms of work efficiency.

[0094] The insulating step (S5) can be a step of receiving the electrode arrangement 1 in the can element 10 in order to connect the cut tabs 111a to the can element 10.

[0095] In the installation step (S5) each of the cut tabs 111a can be bent so that welding is easily carried out while the cut tab 111a is electrically connected to the can element 10 to allow the electrode arrangement 1 to be received in the can element 10 in the state in which the cut tab 111a is bent.

[0096] Since the notch tab 111a has two or more layers, the mechanical strength can be maintained even though the notch tab 111a is bent, and thus the notch tab cannot be easily broken.

[0097] The curved incision tab 111a can have an end that faces the center of a bottom surface of the can element 10.

[0098] The coupling between the base surface of the can element 10 and the slot tab 111a can be carried out by welding the bent part of the slot tab 111a to the base surface of the can element 10.

[0099] In addition, according to another embodiment of the present invention, the curved sections of the multiple cut tabs 111a can overlap the central section of the end of the electrode arrangement 1 in order to be welded and joined simultaneously with the can element 10 together with the electrode tab 121 formed on the central section of the end of the electrode 1.

[0100] Although the secondary battery and its manufacture according to the present invention have been described above with reference to the exemplary drawings, various changes and modifications can be made to it by a person skilled in the art without deviating from the scope and spirit of the invention as set out in the attached claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2017-0048645

[0001] KR 10-2012-0006389

[0006]

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