Multilayer conductive adhesive tape, secondary battery including the same, and method of manufacturing the same

Abstract

The present invention relates to a multilayer conductive tape including an adhesive layer, a conductive layer located on one side of the adhesive layer, an insulating layer located on one side of the conductive layer, and a protective layer for protecting an outer surface of the insulating layer.

Description

Technical Field

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2021-0105969, filed on August 11, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to a multilayer conductive tape and a secondary battery including the multilayer conductive tape, and more specifically, to a multilayer conductive tape, a secondary battery including the multilayer conductive tape, and a method for manufacturing the secondary battery, wherein the multilayer conductive tape prevents performance degradation of the secondary battery due to disconnection at the contact area between the electrode tabs and electrode leads via the multilayer insulating tape. Background Technology

[0003] With technological advancements and increasing demand for mobile devices, the need for batteries as an energy source is rapidly growing. Consequently, numerous studies are being conducted on rechargeable batteries that can meet various requirements.

[0004] In terms of shape, there is an increasing demand for thin prismatic and pouch-shaped secondary batteries that can be used in products such as mobile phones. In terms of materials, there is an increasing demand for lithium-ion batteries, lithium-ion polymer batteries, and the like, which have high energy density, high discharge voltage, and high output stability.

[0005] Typically, a pouch-type secondary battery includes: an electrode assembly, electrode tabs extending from the electrode assembly, electrode leads welded to the electrode tabs, a pouch-type housing material that houses the electrode assembly and is made of a laminate of polymer resin and aluminum, and insulating tape adhered to the portions of the electrode tabs and electrode leads for welding.

[0006] Insulating tape can be used to improve the insulation performance of the positive or negative electrode. However, when the electrode contacts and electrode leads break due to the narrow bonding area and non-conductivity of the insulating tape, the secondary battery will no longer work, so there is a problem that the secondary battery cannot be used.

[0007] Therefore, a secondary battery structure is needed that can fundamentally solve these problems, ensure process stability, and significantly improve defect rates such as electrode tabs and electrode leads breakage. Summary of the Invention

[0008] Technical issues

[0009] The present invention was conceived in the context of the prior art, and the technical problem of the present invention is to provide a secondary battery comprising a multilayer conductive tape, a secondary battery including the multilayer conductive tape, and a method for manufacturing the secondary battery, wherein a conductive layer is placed in the region where the electrode contacts and the electrode leads are in contact, and the conductive layer is conductive to the outside even when a break occurs in the electrode contacts or the electrode leads.

[0010] Technical solution

[0011] An exemplary embodiment of the present invention provides a multilayer conductive tape, comprising: an adhesive layer; a conductive layer located on one side of the adhesive layer; an insulating layer located on one side of the conductive layer; and a protective layer for protecting the outer surface of the insulating layer.

[0012] Another exemplary embodiment of the present invention provides a secondary battery comprising: an electrode assembly in which one or more electrodes and a separator are alternately stacked; a battery housing housing the electrode assembly; electrode tabs protruding from and extending from the electrodes and stacked and welded for each polarity; electrode leads stacked and connected to the electrode tabs and partially protruding to the outside of the battery housing; and the multilayer conductive tape.

[0013] In another exemplary embodiment of the invention, the width W of the multilayer conductive tape extends in the width direction from the end of the electrode assembly facing one surface and the other surface of the battery housing to at least a portion of the portion where the electrode tab and the electrode lead are connected and overlap.

[0014] Another exemplary embodiment of the present invention provides a method for manufacturing a secondary battery, the method comprising: manufacturing an electrode assembly by alternately stacking a plurality of electrodes and a separator; performing pre-welding of electrode tabs disposed at the ends of the plurality of electrodes; performing main welding by overlapping the ends of the electrode tabs and electrode leads and welding the electrode tabs and electrode leads; adhering a multilayer conductive tape to at least one of the upper and lower sides of the overlapping position of the electrode tabs and electrode leads; and performing thermo-press bonding of the adhesive surfaces of the multilayer conductive tape by heat.

[0015] Beneficial effects

[0016] According to an exemplary embodiment of the present invention, the multilayer conductive tape can prevent current flow failures caused by the disconnection or folding of the electrode contacts included in the secondary battery by placing a conductive layer in the area where the electrode contacts and electrode leads are in contact.

[0017] Furthermore, because the multilayer conductive tape is bonded over an area larger than the area where the electrode tabs and electrode leads are soldered, problems such as breakage and folding of the electrode tabs can be prevented. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of insulating tape in related technologies.

[0019] Figure 2 This is a cross-sectional view illustrating a multilayer conductive tape according to an exemplary embodiment of the present invention.

[0020] Figure 3 This is a perspective view illustrating a secondary battery according to an exemplary embodiment of the present invention.

[0021] Figure 4 It is along Figure 3 A partial cross-sectional view of a secondary battery according to an exemplary embodiment of the present invention, taken by line A-A'.

[0022] Figure 5 It is along Figure 3 A partial cross-sectional view of a secondary battery comprising a multilayer conductive tape according to another exemplary embodiment of the present invention, taken by line A-A'.

[0023] Figure 6 This is a flowchart of a method for manufacturing a secondary battery according to an exemplary embodiment of the present invention.

[0024] [Label Explanation]

[0025] 100: Secondary battery

[0026] 10, 10': Multilayer conductive tape

[0027] 11: Adhesive layer

[0028] 12: Conductive layer

[0029] 13: Insulation layer

[0030] 14: Protective layer

[0031] 20: Battery Components

[0032] 30: Electrode contacts

[0033] 40: Electrode leads. Detailed Implementation

[0034] The invention will now be described in detail with reference to the accompanying drawings. However, the drawings are for illustrative purposes only, and the scope of the invention is not limited by the drawings.

[0035] Figure 2This is a cross-sectional view illustrating a multilayer conductive tape 10 according to an exemplary embodiment of the present invention. Figure 3 This is a perspective view illustrating a secondary battery 100 according to an exemplary embodiment of the present invention. Figure 4 It is along Figure 3 A partial cross-sectional view of a secondary battery 100 according to an exemplary embodiment of the present invention, taken by line A-A'. Figure 5 It is along Figure 3 The image shows a partial cross-sectional view of a secondary battery 100 comprising a multilayer conductive tape 10' according to another exemplary embodiment of the present invention, taken along line A-A'.

[0036] The secondary battery 100 includes a multilayer conductive tape 10, an electrode assembly 20, an electrode tab 30, and an electrode lead 40.

[0037] Reference Figure 2 The multilayer conductive tape 10 includes an adhesive layer 11, a conductive layer 12, an insulating layer 13, and a protective layer 14.

[0038] The adhesive layer 11 is in direct contact with the substrate to bond the multilayer conductive tape 10 and impart adhesive properties to the multilayer conductive tape 10. Here, the substrate may be, for example, the electrode contacts 30 and electrode leads 40 of the secondary battery 100, which will be described later.

[0039] The adhesive layer 11 may be made of a resin that has adhesive properties at room temperature. The resin included in the adhesive layer 11 is not particularly limited, as long as it can adhere without damaging the adhered objects; however, for example, it may include one or more of the group consisting of acrylic acid, synthetic rubber, and ethyl acetate.

[0040] Furthermore, the adhesive layer 11 may include a highly conductive material to allow current to pass through the conductive layer 12, which will be described later. In the adhesive layer 11, the highly conductive material may be mixed with a resin having adhesive properties. The highly conductive material may include metallic or carbon-based materials, and may include, for example, any one or more of copper, aluminum, titanium, silicon, magnesium, nickel, and stainless steel.

[0041] Alternatively, as adhesive layer 11, a resin with adhesive properties may be applied to a substrate having a plurality of holes penetrating in the stacking direction of the multilayer conductive tape 10. For example, the substrate may be configured in a grid shape, a dot shape, etc. In adhesive layer 11, a conductive material may be included in at least one of the substrate and the resin.

[0042] For example, the substrate may include metal fibers or foils made of one of the materials selected from nickel, copper, stainless steel, silver and gold, electroplated fibers, electroplated nonwoven fabrics, etc.

[0043] The adhesive layer 11 can be formed with a thickness of 1 μm to 20 μm, preferably with a thickness of 3 μm to 15 μm, and more preferably with a thickness of 6 μm to 12 μm. When the thickness of the adhesive layer 11 is less than 1 μm, the adhesive force decreases, and there is a problem that the adhesive layer 11 peels off from the adherend. When the thickness of the adhesive layer 11 exceeds 20 μm, there is a problem that the volume occupied by it in the adherend becomes too large.

[0044] The conductive layer 12 is located on one side of the adhesive layer 11 and allows current to flow through the multilayer conductive tape 10.

[0045] In other words, when the multilayer conductive tape 10 according to the present invention is attached to the part of the electrode contact 30 and the electrode lead 40 for welding, the current flow path becomes wider except for the electrode contact 30 and the electrode lead 40, thereby achieving the effect of increasing conductivity.

[0046] Furthermore, when the electrode contacts 30 are damaged and broken, such as by being cut or folded, current can flow from the electrode contacts 30 to the electrode leads 40 through the conductive layer 12. That is, in the secondary battery 100 attached with the multilayer conductive tape 10 according to the invention, no performance degradation due to the breakage of the electrode contacts 30 will occur.

[0047] The conductive layer 12 may be formed of a metal. The conductive layer 12 may include a metal or alloy, which includes one or more metallic elements selected from iron, copper, lead, tin, zinc, gold, platinum, mercury, nickel, aluminum, magnesium, cadmium, uranium, thorium, plutonium, beryllium, titanium, zirconium, niobium, vanadium, hafnium, indium, tantalum, molybdenum, tungsten, silicon, germanium, sodium, potassium, and gallium.

[0048] That is to say, the conductive layer 12 can be a layer made of a metal or an alloy of two or more metals.

[0049] For example, the conductive layer 12 may be formed of an aluminum and copper alloy. In this case, the weight ratio of aluminum to copper in the alloy may be 1:2 to 1:5, preferably 1:2 to 1:4, and more preferably 1:3.

[0050] If the weight ratio of aluminum to copper is less than 1:2, the conductive layer 12 becomes heavier, and processing becomes more difficult. Furthermore, when the weight ratio of aluminum to copper is less than 1:5, the strength of the conductive layer 12 decreases.

[0051] The conductive layer 12 preferably has a thickness of 20 μm to 60 μm. More preferably, the thickness of the conductive layer 12 can be 30 μm to 50 μm. When the thickness of the conductive layer 12 is less than 20 μm, the conductivity of the multilayer conductive tape 10 decreases, and when the thickness exceeds 60 μm, the increase in conductivity is not significant, thus resulting in low economic efficiency.

[0052] The insulating layer 13 is located on one side of the conductive layer 12, and may be located on the side of the conductive layer 12 opposite to the adhesive layer 11 with reference to the conductive layer 12.

[0053] The insulating layer 13 increases the insulation between the conductive layer 12 and the outside. That is, the insulating layer 13 can primarily prevent current from flowing from the electrode assembly 20 to the outside.

[0054] The insulating layer 13 may have a thickness of 20 μm to 60 μm. Preferably, the insulating layer 13 may be set to a thickness of 20 μm to 50 μm, more preferably a thickness of 20 μm to 40 μm.

[0055] When the thickness of the insulating layer 13 meets the above range, the insulation efficiency between the conductive layer 12 and the battery casing can be maximized.

[0056] The insulating layer 13 may be formed of an organic material, and the organic material may be selected from the group consisting of polyethylene terephthalate, polyimide, polypropylene, polystyrene, polybutene, polyethylene and combinations thereof.

[0057] The protective layer 14 is located in the opposite direction to the conductive layer 12 with reference to the insulating layer 13, so as to prevent the insulating layer 13 from being damaged.

[0058] The protective layer 14 may include any one or more of organic and inorganic materials. That is, the protective layer 14 may be configured as a single layer made of organic or inorganic materials, or as a multilayer made of organic and inorganic materials.

[0059] For example, when the protective layer 14 is configured as a multilayer structure, the protective layer 14 is formed by sequentially stacking organic material layers, inorganic material layers, and organic material layers, or by having organic material layers surrounded by inorganic material layers. When the inorganic material layers surround the organic material layers as if encapsulating them, the inorganic material layers can protect the organic material layers that are sensitive to oxygen and moisture.

[0060] Alternatively, the protective layer 14 can be configured as a composite material layer consisting of a mixture of organic and inorganic materials. In this case, the weight ratio of organic to inorganic materials in the protective layer 14 can be 1:7 to 1:12, preferably 1:8 to 1:10, and more preferably 1:9.

[0061] When the weight ratio of organic to inorganic materials in the protective layer 14 is less than 1:7, the content of inorganic materials is relatively low, which can reduce heat resistance and strength. Furthermore, when the weight ratio of organic to inorganic materials exceeds 1:12, the moisture permeability of the multilayer conductive tape 100 increases, leading to moisture penetration into the electrode contacts 30 and electrode leads 40.

[0062] In other words, the protective layer 14 can improve the heat resistance and mechanical strength of the multilayer conductive tape.

[0063] The protective layer 14 may have a thickness of 20 μm to 60 μm. Preferably, the protective layer 14 may have a thickness of 20 μm to 50 μm, more preferably 20 μm to 40 μm.

[0064] The multilayer conductive tape 10 according to the present invention may further include a second insulating layer. The second insulating layer is located on the surface opposite to the surface where the insulating layer 13 is located, with reference to the protective layer 14.

[0065] The second insulating layer increases the insulation between the battery housing in which the secondary battery 100 is installed, thereby preventing current from flowing from the electrode assembly 20 to the battery housing.

[0066] The second insulating layer may be formed of an organic material, and the organic material may be selected from the group consisting of polyethylene terephthalate, polyimide, polypropylene, polystyrene, polybutene, polyethylene, and combinations thereof.

[0067] The thickness of the second insulating layer can be from 20 μm to 60 μm. Preferably, the second insulating layer can have a thickness of 20 μm to 50 μm, and more preferably a thickness of 20 μm to 40 μm.

[0068] When the thickness of the second insulating layer meets the above-mentioned range, the sealing force and insulation efficiency between the battery casing and the electrode contacts 30 and leads 40 can be increased. Furthermore, it can prevent moisture from penetrating into the electrode assembly 20 due to damage to the insulating layers 13 and 13 and 24.

[0069] The second insulating layer protects the welded portion where the electrode contacts 30 and electrode leads 40 are welded, and minimizes the gap between the electrode leads 40 and the welded portion and the battery casing, thereby minimizing the sealing interference of the multilayer conductive tape 10 between the electrode leads 40 and the welded portion where the electrode contacts 30 and electrode leads 40 are welded and the battery casing.

[0070] The positive and negative electrodes included in the electrode assembly 20 can be stacked in a pre-welded state, with the positive electrode cells pre-welded to each other and the negative electrode cells pre-welded to each other. In the electrode assembly 20, the electrodes and separators can be stacked in the order of pre-welded negative electrode / separator / positive electrode / separator / negative electrode… Then, the electrode assembly 20 can be housed in a battery casing for main-welding.

[0071] Electrode contacts 30 extend from one side of electrode assembly 20 and may include a positive electrode contact and a negative electrode contact. Electrode assembly 20 may include positive and negative electrode contacts pre-welded to extend from the positive and negative electrode sides, respectively. The positive and negative electrode contacts may be spaced apart from each other by a predetermined distance in the same direction with reference to electrode assembly 20.

[0072] Electrode leads 40 extend from electrode contacts 30 to connect to external objects and can be soldered to electrode contacts 30.

[0073] The multilayer conductive tape 10 can be adhered to the portion where the electrode tab 30 and the electrode lead 40 are connected, so as to electrically connect the electrode tab 30 and the electrode lead 40.

[0074] In the multilayer conductive tape 10, when the connection between the electrode contact 30 and the electrode lead 40 is damaged and the electrode contact 30 is disconnected from the electrode lead 40, current can be transmitted to an external object through the adhesive layer 11 and the conductive layer 12 included in the multilayer conductive tape 10.

[0075] The multilayer conductive tape 10 can be adhered to at least one of the upper and lower sides of the joint between the electrode tab 30 and the electrode lead 40.

[0076] In one exemplary embodiment, the multilayer conductive tape 10 can be adhered to the upper and lower sides of the joint portion of the electrode contact 30 and the electrode lead 40, respectively. The multilayer conductive tape 10 can be sealed by hot-pressing to melt-bond the edges of both ends. Therefore, the multilayer conductive tape 10 can protect the joint portion between the electrode contact 30 and the electrode lead 40 from the influence of external air and oxygen.

[0077] According to an exemplary embodiment, the two end edges of the multilayer conductive tape 10 can refer to the portions in which neither the electrode tab 30 nor the electrode lead 40 is present in a direction perpendicular to the direction in which the electrode lead 40 extends from the electrode tab 30. That is, the multilayer conductive tape 10 can be adhered in a direction perpendicular to the direction in which the electrode lead 40 extends from the electrode tab 30, and portions excluding the electrode tab 30 and the electrode lead 40 can appear between the upper and lower sides of the multilayer conductive tape 10 located where the electrode tab 30 and the electrode lead 40 overlap.

[0078] Here, "upper side" and "lower side" can refer to one side and the other side in the stacking direction of the electrode patch 30 and the electrode lead 40.

[0079] Furthermore, the multilayer conductive tape 10 may cover at least a portion of the area where the electrode contacts 30 and electrode leads 40 are connected and overlap. That is, the width W of the multilayer conductive tape 10 may be wider than the width of the portion where the electrode contacts 30 and electrode leads 40 are connected and overlap. Here, the width R of the overlapping portion of the electrode contacts 30 and electrode leads 40 may refer to its length in the same direction as the width of the multilayer conductive tape 10.

[0080] Reference Figure 4 According to an exemplary embodiment, the width of the multilayer conductive tape 10 is 1.5 to 5 times the width of the portion where the electrode tab 30 and the electrode lead 40 are connected, preferably 2 to 4 times, and more preferably 2.5 to 3.5 times.

[0081] Reference Figure 5 According to another exemplary embodiment, the width of the multilayer conductive tape 10' may extend from the ends of the electrode assembly 20 facing one surface and the other surface of the battery housing in the width direction of the multilayer conductive tape 10' to at least a portion of the portion R where the electrode tabs 30 and the electrode leads 40 are connected to and overlap each other. The ends of the electrode assembly 20 to which the multilayer conductive tape 10' is adhered may include the ends in the direction in which the electrode tabs extend.

[0082] The width W of the multilayer conductive tape 10 refers to the distance in the direction perpendicular to the stacking direction of the electrode patch 30 and the electrode lead 40, or in the direction in which the electrode lead 40 extends from the electrode patch 30.

[0083] Multilayer conductive tape 10 surrounds the entire connection portion of the electrode contact 30 and the electrode lead 40, thereby protecting the electrode contact 30 and the electrode lead 40 from damage and expanding the current flow path. Here, the connection portion is the location where the electrode contact 30 and the electrode lead 40 are stacked and connected, and refers to the overlapping part of the electrode contact 30 and the electrode lead 40. That is to say, the connection portion between the electrode contact 30 and the electrode lead 40 can have the same meaning as the overlapping body or overlapping portion of the electrode contact 30 and the electrode lead 40.

[0084] Multilayer conductive tape 10 is adhered to the connection portion of electrode contact 30 and electrode lead 40, and then hot-pressed to seal the contact surfaces between electrode contact 30 and electrode lead 40 and multilayer conductive tape 10.

[0085] For example, by hot pressing, the protective layer 14 or the second insulating layer 15 is melted by applying a constant temperature to the multilayer conductive tape 10, and the multilayer conductive tape 10 is subjected to external pressure, thereby melting the contact surface between the electrode tab 30 and the electrode lead 40 and the multilayer conductive tape 10.

[0086] Figure 6 This is a flowchart of a method for manufacturing a secondary battery according to an exemplary embodiment of the present invention.

[0087] The method for manufacturing a secondary battery includes: an operation S100 of manufacturing an electrode assembly, an operation S200 of performing pre-welding, an operation S300 of performing main-welding, an operation S400 of adhering a multilayer conductive tape, an operation S500 of performing thermo-press bonding, and an operation S600 of assembling the electrode assembly and the battery casing to manufacture a secondary battery.

[0088] In the operation S100 of manufacturing an electrode assembly, an electrode assembly is manufactured by alternately stacking multiple electrodes and separators, and the multiple electrodes and separators can be stacked in the order of positive electrode, separator, negative electrode, separator and positive electrode...

[0089] More specifically, the electrode assembly may include a plurality of stacked positive electrodes, a plurality of stacked negative electrodes, and a separator between the positive and negative electrodes. Furthermore, electrode tabs of varying polarity may be connected to the positive and negative electrodes.

[0090] In the pre-welding operation S200, the electrode contacts included in the electrode assembly in the electrode assembly manufacturing operation S100 are collected and welded, and each of the positive electrode contact and the negative electrode contact can be welded according to polarity.

[0091] For example, since the electrode assembly includes multiple positive electrodes, it may also include multiple positive electrode tabs. In the electrode assembly, multiple positive electrode tabs are stacked to form a positive electrode tab stack portion, and then the positive electrode tabs can be pre-welded by soldering.

[0092] In addition, pre-welding can be applied to all surfaces where electrode tabs are stacked and in contact.

[0093] In the main welding operation S300, electrode leads are stacked and welded on the ends of electrode contacts, and electrode leads can be welded to the upper or lower part of the electrode contacts.

[0094] Electrode leads can be soldered to electrode contacts by overlapping with the pre-soldered locations of the electrode contacts. For example, the electrode lead is positioned below the pre-soldered surface of the positive electrode contact stacked and soldered on top, allowing all surfaces of the electrode lead in contact with the electrode contact to be soldered.

[0095] The electrode leads can be positioned to overlap the entire surface on which the electrode tabs are pre-welded, or they can be positioned to overlap a portion of the surface on which the electrode tabs are pre-welded.

[0096] In the operation S400 of adhering multilayer conductive tape, the multilayer conductive tape is adhered to at least one of the upper and lower sides of the stacked portion where the electrode contacts and electrode leads are stacked, and in the operation S500 of performing thermo-press bonding, thermo-press bonding is performed by applying heat and pressure to the adhesive surface of the multilayer conductive tape.

[0097] Here, the adhesive surface refers to the surface on which the multilayer conductive tape contacts the electrode tabs or electrode leads when the multilayer conductive tape is adhered. When the multilayer conductive tape is only adhered to the upper side of the stacked portion, an adhesive surface is formed between the electrode tabs and the multilayer conductive tape in the direction of the multilayer conductive tape toward the electrode assembly, and in the opposite direction, an adhesive surface can be formed between the electrode leads and the multilayer conductive tape.

[0098] In addition, the adhesive surfaces can be sealed by hot pressing. For example, heat and pressure are applied to the multilayer conductive tape using a hot press device, and the layer on top of the multilayer conductive tape and in contact with the hot press device melts due to the heat and pressure, allowing the multilayer conductive tape to melt with the electrode contacts or electrode leads.

[0099] Multilayer conductive tape can be hot-pressed at temperatures of 50°C to 300°C and pressures of 0.2 MPa to 1.0 MPa, preferably at temperatures of 100°C to 250°C and pressures of 0.2 MPa to 0.7 MPa, and even more preferably at temperatures of 160°C to 200°C and pressures of 0.2 MPa to 0.4 MPa.

[0100] When the thermo-press bonding conditions are a temperature below 300°C and a pressure below 1.0 MPa, the multilayer conductive tape does not seal with the electrode contacts and electrode leads, and a boundary is formed in the part where the multilayer conductive tape adheres to the electrode contacts or the electrode leads, which can lead to a decrease in the adhesion between the multilayer conductive tape and the electrode contacts and electrode leads.

[0101] Furthermore, when the hot-press bonding conditions exceed 300°C and pressure exceeds 1.0 MPa, the increase in adhesion and sealing performance of multilayer conductive tape is not significant compared to the increase in energy consumption.

[0102] For example, when multilayer conductive tape is adhered to the upper and lower sides of a stacked portion where electrode contacts and electrode leads are stacked and soldered, the multilayer conductive tape on the upper and lower sides of the stacked portion adheres to each other in the portions where there are no electrode contacts and electrode leads.

[0103] In this case, when thermo-press bonding is performed on the adhesive surfaces of the multilayer conductive tape, the parts of the multilayer conductive tape that are bonded to each other can also be sealed by thermo-press bonding, and the multilayer conductive tape can be sealed in the form of an encapsulation.

[0104] The operation S600 of assembling the electrode assembly and battery casing to manufacture a secondary battery may further include the operation S610 of preparing the battery casing, the operation S620 of assembling the battery casing and electrode assembly, and the operation S630 of sealing the battery casing.

[0105] In operation 610 of preparing the battery casing, a battery casing precursor made of a flexible material, such as a laminated sheet, can be pressed with a punch to form a lower casing including a receiving portion in which the electrode assembly can be housed.

[0106] After the electrode assembly is housed in the receiving portion of the lower housing, the upper housing, which covers the electrode assembly from above, can access and seal the lower housing so that the electrode assembly is not separated from the outside of the battery housing. In this case, the battery housing can be sealed such that the electrode tabs and electrode leads are exposed.

[0107] The present invention has been described above with reference to exemplary embodiments thereof; however, those skilled in the art will understand that various corrections and changes may be made to the invention without departing from the spirit and scope of the invention as described in the appended claims.

[0108] Model for implementing invention

[0109] <Example 1>

[0110] Example 1 is Figure 4 The secondary battery shown in the figure according to the present invention is a secondary battery comprising a multilayer conductive tape including an adhesive layer, a conductive layer, an insulating layer, a protective layer, and a second insulating layer, attached to a welded portion for soldering electrode contacts and electrode leads. In this case, the secondary battery according to an exemplary embodiment is manufactured by attaching the multilayer conductive tape after the welded portion is disconnected.

[0111] The adhesive layer is prepared by coating both sides of the copper foil with acrylic resin, and the adhesive layer has a thickness of 10 μm.

[0112] The conductive layer is an aluminum plate with a thickness of 40 μm, and the conductive layer is attached to one surface of the adhesive layer.

[0113] The insulating layer is attached to one surface of the conductive layer in the form of a polypropylene (PP) sheet with a thickness of 40 μm, that is, the opposite surface of the two surfaces of the conductive layer that is in contact with the adhesive layer.

[0114] The protective layer is in the form of polypropylene placed inside the alumina layer in the encapsulation form. The protective layer is attached to one surface of the insulating layer in the form of a 40 μm thick layer containing a combination of alumina and polypropylene, and the second insulating layer is attached to one surface of the protective layer in the form of a 30 μm thick plate containing polypropylene (PP).

[0115] <Example 2>

[0116] Except for attaching a conductive layer of a copper plate with a thickness of 40 μm to one surface of the adhesive layer, Example 2 is a secondary battery configured in the same manner as in Example 1.

[0117] <Comparative Example>

[0118] A comparative example is a secondary battery in which a multilayer adhesive tape, including an adhesive layer and an insulating layer, is attached to the welding area where electrode contacts and electrode leads are soldered. In this case, the secondary battery is manufactured by attaching the multilayer adhesive tape to a high-quality electrode assembly in which no breakage occurs at the soldered portion of the secondary battery according to the comparative example.

[0119] The adhesive layer and the insulating layer are configured in the same manner as in Example 1.

[0120] [Table 1]

[0121]

[0122]

[0123] [Table 2]

[0124]

[0125] The capacity of the secondary battery was measured by charging it to 4.2V at 1C under constant current / constant voltage (CC / CV) conditions at 25°C, and then discharging it to 2.5V at 1C under constant current (CC) conditions, and the discharge capacity was measured.

[0126] For insulation resistance and insulation voltage, leakage current is checked by measuring the resistance for 1 second after applying a voltage of 50V between the negative terminal of the secondary battery and the bag, and between the positive terminal and the bag, and insulation between the positive / negative terminal and the bag is assessed by evaluating the resistance level.

[0127] AC impedance (AC-imp) was measured using an EIS device (Biologic potentiostat).

[0128] Tensile strength was measured using an INSTRON 4465 instrument and in accordance with ASTM D638.

[0129] Referring to Table 1, it can be seen that the physical characteristics of Example 1, including the disconnection at the welded portion where the electrode contacts and electrode leads are welded, such as capacity, insulation resistance, insulation voltage, and AC impedance, are similar to the physical characteristics of the secondary battery of the comparative example with good quality.

[0130] More specifically, since the secondary battery according to Example 1 allows current to pass through the multilayer conductive tape without being affected by the breakage of the welded part, the AC impedance value of Example 1 exhibits characteristics similar to that of the comparative example.

[0131] Furthermore, in the secondary battery according to Example 1, the current does not flow between the welded portion and the battery casing, more specifically, between the conductive layer of the multilayer conductive tape and the insulating layer, protective layer, and second insulating layer of the battery casing. The secondary battery according to Example 1 exhibits insulation resistance and insulation voltage values ​​similar to those of the comparative example with good quality.

[0132] Referring to Table 2, it can be seen that, compared with the comparative example, the tensile strength increased by 21% to 26% in Examples 1 and 2. Here, tensile strength refers to the strength measured when no current flows after at least one of the welded portion and the multilayer conductive tape (or multilayer tape) has been cut.

[0133] In the secondary battery according to the comparative example, when the welded portion with the multilayer tape adhering to it is stretched, the current does not flow when the welded portion is cut off. It can be seen that the tensile strength, which is the strength value when the welded portion is cut off, is relatively small compared with that of Example 1 and Example 2.

[0134] On the other hand, in the secondary batteries according to Examples 1 and 2, current flows through the multilayer conductive tape even when the welded portion is cut. Therefore, in the secondary batteries according to Examples 1 and 2, when both the welded portion and the multilayer conductive tape are cut, the current is interrupted, and thus the tensile strength of Examples 1 and 2 corresponds to the tensile strength up to the point where both the welded portion and the multilayer conductive tape are cut. Therefore, the tensile strength of Examples 1 and 2 is higher than that of the comparative example.

Claims

1. A secondary battery, comprising: An electrode assembly in which one or more electrodes and diaphragms are stacked alternately; A battery housing, in which the electrode assembly is housed; Electrode tabs, which protrude from and extend from the electrode and are stacked and soldered for each polarity; Electrode leads, which are stacked and connected to the electrode tabs and partially protrude to the outside of the battery housing; as well as A multilayer conductive tape, wherein the multilayer conductive tape is adhered to the portion for connection between the electrode contacts and the electrode leads, comprising: Adhesive layer; A conductive layer located on one side of the adhesive layer; An insulating layer located on one side of the conductive layer; and A protective layer used to protect the outer surface of the insulating layer. The width of the multilayer conductive tape extends in the width direction from the end of the electrode assembly facing one surface and the other surface of the battery housing to at least a portion of the portion where the electrode tabs and the electrode leads are connected and overlap.

2. The secondary battery according to claim 1, wherein the conductive layer comprises a metal, and the metal comprises any one or more of copper, aluminum, titanium, magnesium and stainless steel.

3. The secondary battery according to claim 1, wherein the insulating layer is made of a material selected from the group consisting of polyethylene terephthalate, polyimide, polypropylene, polystyrene, polybutene, polyethylene, and combinations thereof.

4. The secondary battery according to claim 1, further comprising: A second insulating layer located on one side of the protective layer.

5. The secondary battery according to claim 1, wherein the adhesive layer comprises a substrate in the form of a mesh and an adhesive resin.

6. The secondary battery according to claim 5, wherein any one or more of the substrate and the resin comprises a conductive material.

7. The secondary battery according to claim 1, wherein the multilayer conductive tape is adhered to at least one of the upper and lower sides in the stacking direction at the location where the electrode contacts and the electrode leads are stacked and connected.

8. The secondary battery according to claim 7, wherein the multilayer conductive tape covers at least a portion of the portion where the electrode tabs and the electrode leads are connected and overlap.

9. The secondary battery according to claim 8, wherein in the multilayer conductive tape, the width of the electrode lead in the direction extending to the electrode tab is greater than the width of the portion where the electrode tab and the electrode lead are connected and overlap.

10. The secondary battery according to claim 7, wherein the multilayer conductive tape seals the contact surfaces of the electrode contacts and the electrode leads with the battery casing.

11. The secondary battery according to claim 7, wherein the multilayer conductive tape is adhered to the upper and lower sides of the location where the electrode tab and the electrode lead are connected and overlapped in a direction perpendicular to the direction in which the electrode lead extends, and The multilayer conductive tape located on the upper and lower sides adheres to and seals each other in the portions where the electrode tabs and electrode leads are not present, in a direction perpendicular to the direction in which the electrode leads extend.

12. A method for manufacturing a secondary battery according to any one of claims 1 to 11, the method comprising: Electrode assemblies are fabricated by alternately stacking multiple electrodes and diaphragms; Perform pre-welding of the electrode tabs collected and welded at the ends of the plurality of electrodes; The main welding is performed by overlapping the ends of the electrode tabs and electrode leads and welding the electrode tabs and electrode leads together; Adhere multilayer conductive tape to at least one of the upper and lower sides of the overlapping position of the electrode tab and the electrode lead; as well as The adhesive surfaces of the multilayer conductive tape are thermo-pressed together using heat.

13. The method of claim 12, wherein performing the thermo-press bonding operation comprises performing thermo-press bonding on the adhesive surfaces of the multilayer conductive tape at a temperature of 50°C to 300°C and a pressure of 0.2 MPa to 1.0 MPa.

14. The method of claim 12, wherein the multilayer conductive tape is adhered to the upper and lower sides of the overlapping position of the electrode tab and the electrode lead, and the portions of the multilayer conductive tape adhered to the upper and lower sides that are in contact with each other are sealed by thermocompression.

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