Electrode assembly manufacturing method

Abstract

The present invention provides an electrode assembly manufacturing method capable of mass production of an electrode assembly of a rechargeable battery, the method comprising: coating a conductive binder solution including a gas generating material on a metal plate material for an electrode tab; forming a release film on a metal plate material for an electrode tab to cover the coated conductive binder solution; drying the conductive adhesive solution to become a conductive adhesive portion; cutting the metal plate material for the electrode tab to form a plurality of strips; cutting the plurality of strips to manufacture a plurality of electrode tabs on which the conductive adhesive portion and the release film are stacked; removing the release film from the electrode tab; and adhering the electrode tab from which the release film has been removed to one surface of an electrode current collector.

Description

[0001] This divisional application is for a patent application for invention with the application date of April 15, 2019, the application number entering the Chinese national phase being 201980010729.8 (international application number PCT / KR2019 / 004512), and the original invention name being "Electrode Assembly Having an Improved Connection Structure between Electrode Tab and Current Collector and Method of Manufacturing the Same".

[0002] Cross - reference to related applications

[0003] This application claims the priority and benefit of Korean Patent Application No. 10 - 2018 - 0071080, filed with the Korean Intellectual Property Office on June 20, 2018, the entire content of which is incorporated herein by reference. Technical field

[0004] The present invention relates to a rechargeable battery and a method of manufacturing the same, and also to an electrode assembly having an improved connection structure between an electrode tab and a current collector and a method of manufacturing the same. Background art

[0005] In recent years, with the sharp increase in the demand for portable electronic devices such as laptop computers, video cameras, and mobile phones, and the comprehensive development of electric vehicles, energy storage batteries, robots, and satellites, many studies have been conducted on rechargeable batteries used as driving power sources for the above - mentioned devices.

[0006] Examples of these rechargeable batteries include nickel - cadmium batteries, nickel - metal hydride batteries, nickel - zinc batteries, and lithium secondary batteries. Among these, since lithium rechargeable batteries have a smaller memory effect compared to nickel - type rechargeable batteries, lithium rechargeable batteries are widely used in high - tech electronic devices due to free charging and discharging, extremely low self - discharge rates, high operating voltages, and high unit - weight energy densities.

[0007] However, when a lithium rechargeable battery is exposed to high temperatures, or when a large current flows through it in a short time due to over - charging, external short - circuit, breakdown, local damage, etc., there is a risk that the battery is heated by infrared heat and explodes. That is, when the pressure or temperature of the battery rises, decomposition reactions of active materials and many side reactions occur, causing the temperature of the battery to rise rapidly, which further accelerates the reaction between the electrolyte and the electrode. Eventually, a thermal runaway phenomenon in which the battery temperature rises sharply occurs, and when the temperature rises to a certain level, the battery may catch fire, and the lithium rechargeable battery may explode due to an increase in the internal pressure of the battery.

[0008] Therefore, various methods are being discussed to effectively control a lithium rechargeable battery when the lithium rechargeable battery is in an abnormal operating state such as an overcurrent state or a high temperature state. As part of the efforts to ensure safety, there are methods of installing devices outside the battery cell and methods of using materials inside the battery cell. PTC and CID devices that utilize temperature changes, protection circuits that control voltage and current, and safety vents that utilize changes in the internal pressure of the battery correspond to the methods of installing devices outside the battery cell, and the method of using materials inside the battery cell is to add materials that can undergo physical, chemical, or electrochemical changes according to changes in temperature, voltage, and current inside the battery.

[0009] In the case of using materials inside the battery cell, there is an advantage that the materials can be applied to all types of batteries without an additional installation process. However, since there are problems such as deterioration of battery performance such as rate characteristics or capacity of the battery due to the addition of materials and unreliable operation, various measures that can bring an obvious current blocking effect while minimizing deterioration of battery performance are being discussed.

[0010] Lithium rechargeable batteries mainly use lithium oxide and carbon materials as the positive electrode active material and the negative electrode active material, respectively. A positive electrode and a negative electrode, on which the positive electrode active material and the negative electrode active material are respectively coated on a current collector, are arranged via a separator interposed between the positive electrode and the negative electrode to construct an electrode assembly, and the electrode assembly is received and sealed together with an electrolyte solution in an outer member.

[0011] Figure 1 is a perspective view of a conventional jelly roll type electrode assembly, and Figure 2 is Figure 1 an exploded perspective view of the electrode assembly shown in

[0012] Referring to Figure 1 and Figure 2 , a conventional jelly roll type electrode assembly 100 includes a positive electrode 110, a negative electrode 120, and a separator 130, and the separator 130 is interposed between the positive electrode 110 and the negative electrode 120.

[0013] The positive electrode 110 includes a plate-shaped positive electrode current collector 111 and a positive electrode active material layer 113 formed on the positive electrode current collector 111. The positive electrode current collector 111 includes a positive electrode non-coated region 115, which is a portion where the positive electrode active material layer 113 is not formed. The positive electrode non-coated regions 115 are arranged on both surfaces of the positive electrode current collector 111.

[0014] A positive electrode tab 140 is attached to the positive electrode non-coated region 115 by welding so that the positive electrode current collector 111 and the positive electrode tab 140 are connected.

[0015] Figure 3 It is a schematic cross-sectional view of a case where a positive electrode tab is welded to a conventional positive electrode current collector.

[0016] Referring to Figure 3 , the positive electrode current collector 111 and the positive electrode tab 140 are disposed between the welding devices 180, and ultrasonic welding or resistance welding is performed. Since the welding device 180 damages the active material layer, as Figure 2 shown, the positive electrode non-coated regions 115 are provided on both surfaces of the positive electrode current collector 111.

[0017] In the conventional negative electrode 120, the same or a similar structure as that of the conventional positive electrode 110 is applied, so that negative electrode non-coated regions 125 are provided on both surfaces of the negative electrode current collector 121.

[0018] The positive electrode non-coated regions 115 provided on both surfaces of the positive electrode current collector 111 and the negative electrode non-coated regions 125 provided on both surfaces of the negative electrode current collector 121 reduce the capacity of the electrode assembly 100 because the active material layer is not formed in the entire space. In a high-output model, the number of positive electrode tabs 140 and negative electrode tabs 160 increases, which causes the areas of the positive electrode non-coated regions 115 and the negative electrode non-coated regions 125 to further increase, thereby further reducing the capacity of the battery cell.

[0019] Therefore, it is necessary to study a lithium rechargeable battery that prevents risks such as explosions caused by overcharging of the lithium rechargeable battery and at the same time minimizes the deterioration of the battery capacity in order to simultaneously meet the trends of high capacity and thinness. SUMMARY OF THE INVENTION

[0020] Exemplary embodiments of the present invention are used to solve the above problems and provide an electrode assembly for a rechargeable battery and a manufacturing method of the electrode assembly to achieve the capacity of a battery cell while obtaining safety against overcharging by improving the connection structure between an electrode tab and a current collector.

[0021] An electrode assembly according to an exemplary embodiment of the present invention includes: an electrode current collector; a non-coated region in which an electrode active material layer is not formed, and the non-coated region is located at one surface of the electrode current collector; an electrode tab disposed at the non-coated region; and a conductive adhesive portion disposed between the non-coated region and the electrode tab, wherein the conductive adhesive portion includes a gas generating material.

[0022] The conductive adhesive portion may further include a conductive material and an adhesive material.

[0023] The binder material, the conductive material, and the gas generating material can form a conductive binder portion in the form of a slurry.

[0024] When the gas generating material reaches the decomposition voltage, gas can be generated, causing the volume of the conductive binder portion to increase.

[0025] The decomposition voltage can be a voltage of 4.5 V or greater.

[0026] The gas generating material can include at least one of Li2CO3, K2CO3, CaCO3, BaCO3, and SrCO3.

[0027] The thickness of the conductive binder portion can be 10 micrometers or less.

[0028] In an exemplary embodiment, the electrode tab can be a metal strip-shaped member having a width and a length. The electrode tab can include an electrode tab overlapping portion and an electrode tab extending portion. The electrode tab overlapping portion is stacked at the non-coated area, and the electrode tab extending portion extends from the electrode tab overlapping portion to the outside of the electrode current collector. And the conductive binder portion can be formed to have the same shape and area as the electrode tab overlapping portion.

[0029] A method for manufacturing an electrode assembly for a rechargeable battery according to another exemplary embodiment of the present invention includes: coating a conductive binder solution including a gas generating material on a metal plate material for an electrode tab; forming a release film on the metal plate material for the electrode tab to cover the coated conductive binder solution; drying the conductive binder solution to become a conductive binder portion; cutting the metal plate material for the electrode tab to form a plurality of strips; cutting the plurality of strips to manufacture a plurality of electrode tabs stacked with the conductive binder portion and the release film; removing the release film from the electrode tab; and adhering the electrode tab from which the release film has been removed to one surface of the electrode current collector.

[0030] The coating of the conductive binder solution can allow the coated area and the non-coated area to be alternately arranged in the lateral direction. The conductive binder solution is coated in the longitudinal direction in the coated area, and the conductive binder solution is not coated in the non-coated area.

[0031] The plurality of strips can be cut such that the electrode tab includes one coated area and one non-coated area.

[0032] The electrode tab may include an electrode tab overlapping portion and an electrode tab extending portion. The electrode tab overlapping portion is stacked at the electrode current collector, and the electrode tab extending portion extends from the electrode tab overlapping portion to the outside of the electrode current collector. The lateral length of the coated area may be the same as the length of the electrode tab overlapping portion, and the lateral length of the non-coated area may be the same as the length of the electrode tab extending portion.

[0033] The adhesion of the electrode tab to one surface of the electrode current collector may adhere the electrode tab to the non-coated area where the electrode active material layer is not formed in one surface of the electrode current collector.

[0034] The conductive adhesive solution may be manufactured in a slurry form and further include a conductive material and an adhesive material.

[0035] When the gas generating material reaches the decomposition voltage, gas may be generated, causing the volume of the conductive adhesive portion to increase.

[0036] The decomposition voltage may be a voltage of 4.5 V or greater.

[0037] The gas generating material may include at least one of Li2CO3, K2CO3, CaCO3, BaCO3, and SrCO3.

[0038] The thickness of the conductive adhesive portion may be 10 micrometers or less.

[0039] According to an exemplary embodiment of the present invention, by including a gas generating material in the conductive adhesive portion between the electrode tab and the electrode current collector, the manufacturing of the electrode for a rechargeable battery can ensure safety in abnormal operating states such as overcharging without increasing resistance.

[0040] Moreover, the electrode tab having a conductive adhesive portion and a release film can be mass-produced by a process of cutting and slicing a metal plate material for the electrode tab on which the conductive adhesive portion and the release film are formed, without a separate welding process. Description of the Drawings

[0041] Figure 1 is a perspective view of a conventional jelly roll type electrode assembly.

[0042] Figure 2 is Figure 1 an exploded perspective view of the electrode assembly before being wound.

[0043] Figure 3 is a schematic cross-sectional view when a positive electrode tab is welded to a conventional positive electrode current collector.

[0044] Figure 4Is a perspective view of a jelly roll type electrode assembly according to an exemplary embodiment of the present invention.

[0045] Figure 5 Is Figure 4 An exploded perspective view of the electrode assembly before being wound.

[0046] Figure 6 Is Figure 5 An enlarged top plan view of part A of

[0047] Figure 7 Is along Figure 6 Cross-sectional view taken along the direction V-V’ of

[0048] Figure 8 Is Figure 7 An enlarged top plan view of part C of

[0049] Figure 9 Is Figure 7 An enlarged cross-sectional view of part C of after gas generation

[0050] Figure 10 Is a perspective view of an electrode tab according to an exemplary embodiment of the present invention.

[0051] Figure 11 And Figure 12 Are views for explaining a method of manufacturing an electrode assembly according to an exemplary embodiment of the present invention. Detailed Description

[0052] Hereinafter, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. As those skilled in the art will recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention.

[0053] To make the description of the present invention clear, parts not relevant to the description are omitted, and throughout this specification, the same reference numerals will be used to refer to the same or similar parts.

[0054] In addition, for better understanding and ease of description, the dimensions and thicknesses of each configuration shown in the drawings are arbitrarily shown, but the present invention is not limited thereto. In the drawings, for clarity, the thicknesses of layers, films, plates, regions, etc. are exaggerated. In the drawings, for better understanding and ease of description, the thicknesses of some layers and regions are exaggerated.

[0055] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or there can be intervening elements. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. Further, in the specification, the words "on" or "above" mean positioned on or below the target portion and do not necessarily mean positioned on the upper side of the target portion based on the direction of gravity.

[0056] Additionally, unless there is an express contrary description, the word "comprise" and variations such as "comprises" or "comprising" shall be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0057] Furthermore, in this specification, the phrase "in a plan view" means observing the target portion from the top, and the phrase "in a cross-sectional view" means observing the longitudinally cut cross-section of the target portion from the side.

[0058] Figure 4 is a perspective view of a jelly-roll type electrode assembly according to an exemplary embodiment of the present invention. Figure 5 is Figure 4 exploded perspective view of the electrode assembly before being wound. Figure 6 is Figure 5 enlarged top plan view of part A of Figure 7 is along Figure 6 cross-sectional view taken along the direction V-V' of Figure 8 is Figure 7 enlarged top plan view of part C of Figure 9 is Figure 7 enlarged cross-sectional view of part C of

[0059] Referring to Figure 4 and Figure 5 , the electrode assembly 200 according to this exemplary embodiment includes a pair of electrodes and a separator 230 interposed between the pair of electrodes. The pair of electrodes includes a positive electrode 210 and a negative electrode 220. For ease of explanation, Figure 5 shows the state before the electrode assembly 200 is wound. Referring to Figure 5 , the positive electrode 210, the separator 230, and the negative electrode 220 are formed in a plate shape and stacked in order. These electrode assemblies 200 are encapsulated together with an electrolyte solution and accommodated in an external member (not shown) to be manufactured into a rechargeable battery.

[0060] Since the configurations of the positive electrode 210 and the negative electrode 220 are the same or similar to each other, in Figure 5 , the description will be based on the positive electrode 210 among the electrodes.

[0061] Reference Figure 5 , the positive electrode 210 includes a plate-shaped positive electrode current collector 211 and a positive electrode active material layer 213 formed on the positive electrode current collector 211. The positive electrode current collector 211 includes a positive electrode non-coated region 215 in which the positive electrode active material layer 213 is not formed. As shown in the figure, the positive electrode active material layer 213 is preferably formed on both surfaces of the positive electrode current collector 211. The positive electrode active material layer 213 is coated on a part of the positive electrode current collector 211, and as Figure 5 shown, as an exemplary embodiment, a rectangular region may be reserved at one end in the longitudinal direction of the positive electrode current collector 211 while coating the positive electrode active material layer 213. The portion where the positive electrode active material layer 213 is not formed corresponds to the positive electrode non-coated region 215. The positive electrode non-coated region 215 according to this exemplary embodiment is formed only on one side of the positive electrode current collector 211, which is different from the case in the conventional technology where the positive electrode non-coated region 215 is formed on both surfaces of the positive electrode current collector 211. The positive electrode tab 240 is adhered to the positive electrode non-coated region 215, and the positive electrode tab 240 and the positive electrode 210 are electrically connected to each other. In this exemplary embodiment, the positive electrode tab 240 may be partially bonded to the positive electrode non-coated region 215 by a conductive adhesive to be described later, and reference will be made to Figure 7 etc. for the description thereof.

[0062] By attaching the positive electrode tab 240 by means of the conductive adhesive portion 250 instead of by conventional welding, the positive electrode non-coated region 215 can be formed only on one side of the electrode current collector without damaging the positive electrode active material layer 213. Therefore, the area of the positive electrode active material layer 213 can be increased to increase the amount of the active material, thereby increasing the capacity of the rechargeable battery. In particular, in the battery of the high-power model, since the number of electrode tabs is increased, the capacity improvement effect is greater compared to the case in the conventional battery.

[0063] However, the position and shape of the non-coated region 215 of the positive electrode are not limited thereto, but can be modified. For example, the non-coated region 215 of the positive electrode can be formed as a rectangular region at one end in the width direction of the positive electrode current collector 211. Moreover, the non-coated region 215 of the positive electrode can be formed as a rectangular region at the center of the positive electrode current collector 211. In addition, in the present exemplary embodiment, the non-coated region 215 of the positive electrode is formed to extend from one side to the other side of the positive electrode current collector 211. However, the non-coated region 215 of the positive electrode can have a minimum size that is only located in the region overlapping with the positive electrode tab 240. The negative electrode 220 includes a negative electrode current collector 221 having a plate-like shape similar to the above positive electrode 210 and a negative electrode active material layer 223 formed on the negative electrode current collector 221, and the negative electrode current collector 221 includes a non-coated region 225 of the negative electrode, in which the negative electrode active material layer 223 is not formed. The above content regarding the positive electrode 210 can also be applied to the components related to the negative electrode 220.

[0064] Referring to Figure 5 , the non-coated region 215 of the positive electrode is disposed at one end in the length direction of the positive electrode current collector 211, and the non-coated region 225 of the negative electrode is disposed at one end in the length direction of the negative electrode current collector 221, but this end is opposite to the end where the non-coated region 215 of the positive electrode is disposed. However, the positions of the non-coated region 215 of the positive electrode and the non-coated region 225 of the negative electrode are not limited thereto, and their positions can be the same or can overlap with each other.

[0065] As the material of the positive electrode current collector 211, aluminum is mainly used. In addition, the material of the positive electrode current collector 211 can be stainless steel, nickel, titanium, carbon, or aluminum, or can be set to perform surface treatment on the surface of stainless steel by carbon, nickel, titanium, silver, etc. Moreover, there is no limitation on the material of the positive electrode current collector 211 as long as the material is a material having high conductivity and not causing chemical changes in the rechargeable battery.

[0066] As the negative electrode current collector 221, a copper material is mainly used. In addition, the material of the negative electrode current collector 221 can be stainless steel, aluminum, nickel, titanium, sintered carbon, or copper, or can use surface treatment on the surface of stainless steel by carbon, nickel, titanium, silver, etc. and can use an aluminum-cadmium alloy.

[0067] The positive electrode active material forming the positive electrode active material layer 213 is a lithium-containing active material, and as a representative example, metal oxides such as LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiFePO4, or Li 1+z Ni 1-x-y Co x M yO2 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1, 0 ≤ z ≤ 1, where M is a metal such as Al, Sr, Mg, La, or Mn). The negative electrode active material forming the negative electrode active material layer 223 is a carbon-containing active material, and as the negative electrode active material, carbon materials such as crystalline carbon, amorphous carbon, carbon composites, carbon fibers, etc., or lithium metal, lithium alloys, etc. can be used.

[0068] In addition to the active material, the positive electrode active material layer 213 and the negative electrode active material layer 223 may further include a binder and a conductive material. The binder has the function of easily adhering active material particles to each other and easily adhering the active material to the current collector, and typical examples may include polymers such as polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, butadiene styrene acrylate rubber, epoxy resin, nylon, etc. However, the binder is not limited thereto. The conductive material provides conductivity to the electrode, and the conductive material can be any electronically conductive material that does not cause chemical changes in the battery configuration, and examples may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fibers, metal-based materials such as metal powders or metal fibers of copper, nickel, aluminum, silver, etc., conductive polymers such as polyphenylene derivatives, or mixtures of conductive materials.

[0069] The spacer 230 is not particularly limited as long as the spacer 230 is a porous material. The spacer 230 can be made of a porous polymer layer, such as a porous polyolefin layer, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene - vinyl acetate copolymer, poly(ethylene oxide), cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylated amylose, cyanoethylated polyvinyl alcohol, cyanoethylated cellulose, cyanoethylated sucrose, amylose, carboxymethyl cellulose, acrylonitrile styrene butadiene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polyether ether ketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyvinylnaphthalene, non-woven fabric layer, a layer having a porous network structure, or a mixture thereof.

[0070] One surface or both surfaces of the spacer 230 may be attached with inorganic particles. The inorganic particles are preferably inorganic particles having a high dielectric constant of 5 or greater, and more preferably inorganic material particles having a dielectric constant of 10 or greater and a low density. Thus, the lithium ions moving in the battery cell can be easily transferred. Non-limiting examples of inorganic particles having a high dielectric constant of 5 or greater include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), Pb(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, HfO2, SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, Y2O3 or mixtures thereof.

[0071] Referring to Figure 5 and Figure 6 , the positive electrode tab 240 may be a metal strip-shaped member having a predetermined width and length. The positive electrode tab 240 overlaps with the non-coated region 215 of the positive electrode current collector 211 of the positive electrode to be electrically connected to the positive electrode current collector 211. Specifically, the positive electrode tab 240 includes a positive electrode tab overlapping portion 241 and a positive electrode tab extending portion 242. The positive electrode tab overlapping portion 241 is stacked on the positive electrode current collector 211, and the positive electrode tab extending portion 242 protrudes from one end of the positive electrode current collector 211 located in the positive electrode tab overlapping portion 241 and extends to the outside.

[0072] The positive electrode tab overlapping portion 241 is fixed to the non-coated region 215 of the positive electrode current collector 211 of the positive electrode. The positive electrode 210 to which the positive electrode tab 240 is fixed is stacked and wound with the separator 230 and the negative electrode 220 in sequence, so that the positive electrode tab overlapping portion 241 overlaps with the positive electrode 210 and the separator 230.

[0073] As Figure 7 shown, the positive electrode tab 240 is attached to the non-coated region 215 of the positive electrode current collector 211 by the conductive adhesive portion 250 instead of welding. Thus, the positive electrode 210 and the positive electrode tab 240 are electrically connected. The conductive adhesive portion 250 has an adhesive to fix the positive electrode tab 240 to the positive electrode current collector 211.

[0074] Specifically, the conductive adhesive portion 250 can be formed to have the same shape and area as the positive electrode tab overlapping portion 241. It is necessary to obtain a length or area of the conductive adhesive portion 250 that satisfies the minimum required amount of adhesive. However, in the case of a high-power model, when the area of the positive electrode tab overlapping portion 241 is narrow, the temperature may locally rise due to current concentration. Therefore, the conductive adhesive portion 250 can be formed to have the same area as the entire area of the positive electrode tab overlapping portion 241 that contacts the positive electrode current collector 211.

[0075] Referring to Figure 8 , the conductive adhesive portion 250 includes an adhesive material 251, a conductive material 252, and a gas generating material 253. The adhesive material 251 should not react with the electrolyte solution. For example, the adhesive material 251 is preferably an acrylate series. Among the adhesive materials 251, the adhesive material 251 can be: butyl acrylate / 4-hydroxybutyl acrylate = 98:2 or 2-ethylhexyl acrylate / acrylic acid = 98:2.

[0076] The positive electrode tab 240 can be formed of the same type of metal material as the positive electrode current collector 211. For example, the metal material can be aluminum. In this case, the conductive material 252 of the conductive adhesive portion 250 in the positive electrode 210 is preferably one of aluminum particles, carbon nanotubes (CNT), and carbon black. Specifically, the conductive material 252 is preferably aluminum particles. Therefore, an aluminum material-based current path can be provided between the positive electrode tab 240 - the conductive adhesive portion 250 - the positive electrode current collector 211 without increasing the contact resistance. The aluminum particles can be spherical particles.

[0077] The negative electrode tab 260 can have the same type of metal material as the negative electrode current collector 221. For example, the metal material can be copper. In this case, the conductive material (not shown) of the conductive adhesive portion in the negative electrode 220 is preferably one of CNT, carbon black, and copper particles. Specifically, the conductive material is preferably copper particles. Therefore, a copper material-based current path can be provided between the negative electrode tab 260 - the conductive adhesive portion (not shown) - the negative electrode current collector 221 without increasing the contact resistance.

[0078] In the normal operating state of the rechargeable battery, compared with the case where the gas generating material 253 is not included, due to the low-resistance electrical channels of the conductive material 252, the conductive adhesive portion 250 has conductivity with a resistance level that is not significantly increased.

[0079] The gas generating material 253 is composed of a material that decomposes to generate gas when a predetermined voltage is reached. Herein, the predetermined voltage can be defined as the decomposition voltage for causing the gas generating material 253 to decompose to generate gas, and the predetermined voltage has different values according to the type of the gas generating material 253.

[0080] As Figure 8 and Figure 9 shown in

[0081] the conductive adhesive part 250 has a first thickness X before reaching the decomposition voltage. However, when the decomposition voltage is reached due to an abnormal operating state and then gas is generated by the gas generating material 253, the volume of the conductive adhesive part 250 increases due to the generated gas, such that the thickness of the conductive adhesive part 250 can become a second thickness Y greater than the first thickness X. According to the increased volume of the conductive adhesive part 250, the flow of the conductive material 252 occurs, and the distance between the conductive materials 252 increases. Since the distance between the conductive materials 252 increases, the resistance of the conductive adhesive part 250 increases sharply, which leads to an increase in the resistance and voltage of the battery cell, thereby reaching the termination voltage. Through the above process, abnormal operating states such as overcharging or over-discharging are terminated, and the stability of the secondary battery can be ensured.

[0082] The conductive adhesive portion 250 including an adhesive material 251, a conductive material 252, and a gas generating material 253 may be in a form coated between an electrode current collector and an electrode tab in a slurry form. Since the conductive adhesive portion 250 is in a slurry form, it is possible to more easily adjust the thickness of the conductive adhesive portion 250, or the content of the gas generating material 253 in the conductive adhesive portion 250 can be adjusted.

[0083] As the content of the gas generating material 253 increases, the amount of gas generated at a predetermined voltage in an abnormal operating state increases, and thus the end voltage can be reached more quickly. However, at the same time, the gas acts as a resistance in the battery, which may deteriorate the performance of the battery. The content needs to be appropriately adjusted according to the field in which the battery is used. In an exemplary embodiment of the present invention, by adjusting the slurry thickness or by controlling the content of the gas generating material 253, the resistance of the conductive adhesive portion 250 can be freely adjusted for each manufactured battery, thereby reducing the manufacturing cost of the battery without any additional process, and the voltage level reached by overcharging or over-discharging and the resistance of the conductive adhesive portion 250 can be freely adjusted for each manufactured battery, thereby reducing the cost of battery manufacturing.

[0084] In addition, since the conductive adhesive portion 250 is coated in a slurry form, the adhesive material 251, the conductive material 252, and the gas generating material 253 are dispersed and do not concentrate in a specific portion, thereby effectively ensuring conductivity, adhesion degree, and the degree of reaching the end voltage.

[0085] Compared with the conductive adhesive portion 250 of the adhesive material 251, the conductive material 252, and the gas generating material 253, the weight ratio of the adhesive material 251 is preferably fixed at 40%, the weight ratio of the conductive material 252 is preferably 30% to 50%, and the weight ratio of the gas generating material 253 is preferably 10% to 30%.

[0086] Since the conductive adhesive portion 250 can act as a resistance in the battery cell, the thickness of the conductive adhesive portion 250 is preferably less than 10 micrometers.

[0087] As described with reference to Figure 3 In the conventional technology, uncoated regions where the active material layer is not coated are provided on both surfaces of the electrode current collector and the tabs are welded to the uncoated regions. However, in an exemplary embodiment of the present invention, since adhesion is performed by the conductive adhesive portion 250 instead of welding, as Figure 5 and Figure 7As shown, even in a state where the positive electrode active material layer 213 is completely coated on one surface of the positive electrode current collector 211, a positive electrode non-coated region 215 can be formed on the other surface of the positive electrode current collector 211 to form the positive electrode tab 240. Therefore, since no non-coated region is formed on the surface opposite to the surface to which the positive electrode tab 240 adheres, sufficient capacity can be ensured. Since the structures of the positive electrode 210 and the negative electrode 220 are the same as or similar to each other, battery capacity can also be ensured even in the case of the negative electrode 220.

[0088] If a gas generating material is provided in the electrode layer containing the active material to ensure stability against overcharging, external short circuit, needle puncture, local damage, etc., the amount of the active material is reduced due to the space occupied by the gas generating material and the battery capacity is decreased. However, according to an exemplary embodiment of the present invention, by providing the gas generating material in the conductive adhesive portion 250 between the electrode current collectors 211 and 221 and the electrode tabs 240 and 260, battery deterioration caused by the reduction of the active material is minimized.

[0089] Figure 10 is a perspective view of an electrode tab according to an exemplary embodiment of the present invention. Figure 10 The electrode tab 360 of can be used as the above-mentioned positive electrode tab 240 or negative electrode tab 260 in the manufacture of the electrode assembly 200.

[0090] Referring to Figure 10 , the electrode tab 360 is electrically connected to the electrode current collector, and the electrode tab 360 is a metal strip-shaped member having a width and a length. The electrode tab 360 includes an electrode tab overlapping portion 361 and an electrode tab extending portion 362. The electrode tab overlapping portion 361 is stacked at the electrode current collector, and the electrode tab extending portion 362 extends from the electrode tab overlapping portion 361 to the outside of the electrode current collector. The conductive adhesive portion 370 and the release film 380 are stacked at the electrode tab overlapping portion 361 in the same shape and area as the electrode tab overlapping portion 361.

[0091] Hereinafter, a method for manufacturing an electrode assembly capable of mass-producing a rechargeable battery is described.

[0092] Figure 11 and Figure 12 are views for explaining a method for manufacturing an electrode assembly according to the present invention.

[0093] A binder material, a conductive material, and a gas generating material are mixed to produce a conductive adhesive solution in the form of a slurry. As described above, the binder material should not react with the electrolyte solution, and for example, the binder material is preferably an acrylate series. The gas generating material is not particularly limited as long as it is a material that generates gas when a predetermined voltage is reached, and for example, materials such as Li2CO3, K2CO3, CaCO3, BaCO3, or SrCO3 can be used. In particular, the gas generating material is preferably Li2CO3.

[0094] Referring to Figure 11 , the conductive adhesive solution is coated on the metal plate material 359 for tabbing. In this case, as Figure 11 shown, coating regions 374 and non - coating regions 376 are alternately formed in the lateral direction. The conductive adhesive solution is coated in the longitudinal direction in the coating regions 374, and no conductive adhesive solution is coated in the non - coating regions 376. The lateral length a of the coating region 374 is the same as the length of the overlapping portion 361 of the electrode tab of Figure 10 , and the lateral length b of the non - coating region 376 is the same as the length of the extending portion 362 of the electrode tab of Figure 10 . The coating region 374 is formed in a strip pattern instead of being formed on the entire surface of the metal plate material 359 for tabbing. This forming method can be carried out by using a slot die coating similar to that for coating the electrode active material layer, or by setting a barrier layer such as a bar on the non - coating region 376 and spraying the conductive adhesive solution on the barrier layer.

[0095] Next, a release film covering the coating regions 374 and non - coating regions 376 is stacked on the metal plate material 359 for tabbing.

[0096] Next, the conductive adhesive solution in the coating region 374 is dried to transform into a conductive adhesive portion 370.

[0097] Next, as Figure 12 shown, in order to be suitable for the width of the electrode tab 360, the Figure 11 metal plate material 359 for tabbing is cut into a plurality of strips 359' along the lateral direction.

[0098] Next, in any one of the strips 359', when the strip 359' is cut such that it includes one coating region 374 and one non - coating region 376, one can obtain the same as Figure 10A plurality of electrode tabs 360 similar to those in [description], the conductive adhesive portions 370 and the release films 380 of the plurality of electrode tabs 360 are stacked at the electrode tab overlapping portion 361 in the same shape and area as the electrode tab overlapping portion 361.

[0099] During the manufacturing process of the electrode assembly 200, after inserting the strip 359' in the form of a reel into a winding machine and cutting the strip 359' in the winding machine such that it includes one coated area 374 and one non-coated area 376 to obtain the electrode tab 360, the electrode tab 360 can be adhered to the electrode current collector to manufacture the electrode assembly without cumbersome welding through a series of processes of removing the release film 380 so as to dispose the conductive adhesive portion 370 at the positive non-coated area 215 and / or the negative non-coated area 225.

[0100] The electrode tab according to the present invention can replace the electrode tab of the conventional welding method for manufacturing an electrode assembly and a rechargeable battery including the electrode assembly. The electrode tab according to the present invention is manufactured as an adhesive tab to manufacture a rechargeable battery by omitting the conventional complex welding process and through a simple operation of peeling off the release film and bonding the electrode tab to the electrode current collector. In order to attach the tab to the current collector during the conventional electrode assembly manufacturing process, since the ultrasonic welding process is performed separately, there is a problem of deteriorated efficiency due to equipment costs and maintenance costs related to welding. In the present invention, this problem is solved by using an electrode tab attached with a release film.

[0101] The electrode assembly of the present invention that can be manufactured by this method can allow the connection of the electrode tab and the electrode current collector without damaging the active material layer. The non-coated area is formed only on one surface of the current collector, resulting in an increase in the capacity of the rechargeable battery. Moreover, by disposing the gas generation material for ensuring safety at the conductive adhesive portion between the electrode current collector and the electrode tab instead of in the electrode layer, the deterioration of battery efficiency caused by the reduction of the active material can be minimized.

[0102] As described above, according to the present invention, by improving the connection structure between the electrode tab and the current collector, it is possible to ensure safety against abnormal operating states such as overcharging and external short circuits while manufacturing a rechargeable battery that minimizes the limitation of battery capacity. In particular, in a high-power model with an increased number of electrode tabs, the current blocking effect and the battery capacity improvement effect are more obvious.

[0103] Although the present invention has been specifically shown and described with reference to the exemplary embodiments of the present invention, it should be understood that the present invention is not limited to the disclosed embodiments, but on the contrary, can be modified.

[0104] Description of Reference Numerals

[0105] 200: Electrode assembly

[0106] 250, 370: Conductive adhesive part

[0107] 251: Adhesive material

[0108] 252: Conductive material

[0109] 253: Gas generating material

Claims

1. A method for manufacturing an electrode assembly, comprising: Coat a metal plate material for an electrode tab with a conductive adhesive solution including a gas generating material; Form a release film on the metal plate material for the electrode tab to cover the coated conductive adhesive solution; Dry the conductive adhesive solution to become a conductive adhesive portion; Cut the metal plate material for the electrode tab to form a plurality of strips; Cut the plurality of strips to manufacture a plurality of electrode tabs stacked with the conductive adhesive portion and the release film; Remove the release film from the electrode tab; And Adhere the electrode tab from which the release film has been removed to one surface of an electrode current collector.

2. The method for manufacturing an electrode assembly according to claim 1, wherein, The coating of the conductive adhesive solution allows the coated areas and the non-coated areas to be alternately arranged in the lateral direction, with the conductive adhesive solution coated in the longitudinal direction in the coated areas and not coated in the non-coated areas.

3. The method for manufacturing an electrode assembly according to claim 2, wherein, Cut the plurality of strips such that the electrode tab includes one coated area and one non-coated area.

4. The method for manufacturing an electrode assembly according to claim 3, wherein, The electrode tab includes an electrode tab overlapping portion and an electrode tab extending portion. The electrode tab overlapping portion is stacked at the electrode current collector, and the electrode tab extending portion extends from the electrode tab overlapping portion to the outside of the electrode current collector, and The lateral length of the coated area is the same as the length of the electrode tab overlapping portion, and the lateral length of the non-coated area is the same as the length of the electrode tab extending portion.

5. The method for manufacturing an electrode assembly according to claim 1, wherein, The adhesion of the electrode tab to one surface of the electrode current collector adheres the electrode tab to a non-coated area of one surface of the electrode current collector where no electrode active material layer is formed.

6. The method for manufacturing an electrode assembly according to claim 1, wherein, The conductive adhesive solution is manufactured in a slurry form and further includes a conductive material and an adhesive material, wherein the conductive material provides conductivity to the electrode, and the conductive material is any electronically conductive material that does not cause a chemical change in the battery configuration.

7. The method for manufacturing an electrode assembly according to claim 1, wherein, The gas generating material includes at least one of Li2CO3, K2CO3, CaCO3, BaCO3, and SrCO3.

8. The method for manufacturing an electrode assembly according to claim 1, wherein, The thickness of the conductive adhesive portion is 10 micrometers or less.

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