Energy storage system

Abstract

One embodiment of the present invention, in order to achieve the described technical objective, may provide an energy storage system manufacturing method comprising the steps of: receiving, in a pouch, a lithium electrode assembly comprising a lithium electrode terminal protruding to a first side of the pouch, a negative electrode assembly comprising a negative electrode terminal, a positive electrode assembly comprising a positive electrode terminal, and an electrolyte; doping the negative electrode assembly with lithium by electrically connecting the lithium electrode terminal and the negative electrode terminal; extracting the lithium electrode assembly from the pouch by cutting the pouch along a cut line which is formed so as to be spaced apart from the first side of the pouch at a predetermined interval; and sealing the cut surface of the pouch cut along the cut line.

Description

Energy storage devices

[0001] The present invention relates to a storage device for storing energy such as electrical energy.

[0002] Lithium-ion capacitors require a process of pre-doping lithium into the negative electrode to stabilize internal resistance. Generally, the negative electrode and lithium metal are assembled into a temporary pouch cell, an electrolyte is injected, and then an external voltage is applied to move lithium to the negative electrode material for doping. Once the doping reaches the target level, the temporary pouch is disassembled to remove the lithium metal and auxiliary components, and the doped negative electrode is reassembled with a separately prepared positive electrode and separator to manufacture the final pouch cell.

[0003] This method has the advantage of controlling the doping rate and amount within a certain range by adjusting conditions such as electrolyte composition, temperature, and current while maintaining existing facilities. As a result, it offers the effect of rapid voltage recovery during the initial cycle and improved output characteristics during low-temperature operation.

[0004] On the other hand, during the disassembly process, lithium doped on the cathode surface may be depleted, reducing the doping amount, or surface damage may degrade doping uniformity, leading to variations between cells. Changes in interface conditions due to contact with air or moisture can increase internal resistance or lower initial efficiency, while the ingress of contaminants such as dust into the device can cause localized short circuits in specific areas, resulting in reduced yield. Adding cleaning and drying steps to mitigate these issues increases process steps and extends operating time, thereby lowering productivity and simultaneously increasing quality variability and cost burdens.

[0005] One embodiment of the present invention has the technical objective of providing a method for manufacturing an energy storage device that can prevent a short circuit within an electrode element by reducing the possibility of external foreign matter entering the energy storage device.

[0006] Another embodiment of the present invention has the technical objective of providing a method for manufacturing an energy storage device that prevents deformation of the electrode element during the lithium electrode removal process, thereby minimizing the impact on the operating characteristics of the device.

[0007] Another embodiment of the present invention has the technical objective of providing a method for manufacturing an energy storage device that can improve the productivity of the energy storage device by reducing the equipment and time required for the process.

[0008] The problems to be solved according to one embodiment of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0009] An embodiment of the present invention for achieving the aforementioned technical problem may provide a method for manufacturing an energy storage device comprising the steps of: accommodating a lithium electrode assembly including a lithium electrode terminal protruding toward a first side of a pouch, a negative electrode assembly including a negative electrode terminal, a positive electrode assembly including a positive electrode terminal, and an electrolyte in the pouch; electrically connecting the lithium electrode terminal and the negative electrode terminal to dope the negative electrode assembly with lithium; cutting the pouch along a cutting line formed at a predetermined distance from the first side of the pouch to withdraw the lithium electrode assembly from the pouch; and sealing the cut surface of the pouch cut along the cutting line.

[0010] According to one embodiment of the present invention, by omitting the disassembly process, the possibility of external foreign matter entering is reduced, thereby preventing a short circuit within the electrode element.

[0011] According to one embodiment of the present invention, the electrode element and the electrolyte are fixed within the pouch even when the lithium electrode is removed, thereby suppressing deformation of the electrode element and reducing the impact on the operation of the device in the future.

[0012] According to one embodiment of the present invention, by omitting the reassembly process, equipment requirements and processing time are reduced, thereby improving the productivity of the energy storage device.

[0013] In addition to the effects mentioned above, other features and advantages of the present invention are described below, or will be clearly understood by those skilled in the art from such description and explanation.

[0014] FIG. 1 is a perspective view showing an energy storage device according to one embodiment of the present invention.

[0015] Figure 2 is a diagram showing in detail the configuration of an electrode element included in an energy storage device.

[0016] FIGS. 3 to 11 are drawings illustrating a method for manufacturing an energy storage device according to one embodiment of the present invention.

[0017] FIGS. 12 to 15 are drawings illustrating a method for manufacturing an energy storage device according to another embodiment of the present invention.

[0018] FIGS. 16 and 17 are drawings illustrating a method for manufacturing an energy storage device according to another embodiment of the present invention.

[0019] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are intended to ensure that the disclosure of the present invention is complete and to enable those skilled in the art to easily understand the invention.

[0020] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the matters shown in the drawings. Throughout the specification, identical components may be referred to by the same reference numerals. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0021] Where terms such as “comprising,” “having,” or “consisting of” are used in this specification, other parts may be added unless the expression “only” is used. Where a component is expressed in the singular, it includes the plural unless specifically stated otherwise.

[0022] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0023] For example, when the positional relationship between two parts is described using expressions such as “on,” “upper,” “lower,” or “next to,” one or more other parts may be located between the two parts unless expressions such as “immediately” or “directly” are used.

[0024] Spatially relative terms such as “below” or “beneath,” “lower,” “above,” and “upper” may be used to facilitate the description of the relationship between one element or component and another, as illustrated in the drawings. Spatially relative terms should be understood as terms that include different orientations of the element during use or operation, in addition to the orientations illustrated in the drawings. For example, if an element illustrated in the drawings is flipped, an element described as being “below” or “beneath” of another element may be placed “above” of that other element. Therefore, the exemplary term “below” may include both the lower and upper directions. Similarly, the exemplary terms “above” or “upper” may include both the upper and lower directions.

[0025] In the case of an explanation of a temporal relationship, for example, when the temporal sequence is explained using expressions such as “after,” “following,” “next to,” or “before,” it may include cases where the sequence is not continuous unless expressions such as “immediately” or “directly” are used.

[0026] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0027] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item, and the third item” may mean not only the first item, the second item, or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item, and the third item.

[0028] Each feature of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0029] In assigning reference numerals to the components of each drawing describing the embodiments of the present invention, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings.

[0030] According to one embodiment of the present invention, an energy storage device (100) may include a pouch (110) and an electrode element (120). In this specification, the energy storage device may include a capacitor, an ultracapacitor, a supercapacitor, a secondary battery, etc.

[0031] The pouch (110) may include a space for accommodating an electrode element (120) together with an electrolyte. The pouch (110) may be defined as a laminate outer material, a case, a pouch outer material, or a pouch case.

[0032] A pouch (110) can have a recess formed on one side by pressing or drawing. Specifically, an electrode element (120) can be accommodated within the recess formed on the outer surface of the pouch (110).

[0033] The pouch (110) may include a first side, a second side, a third side, and a fourth side.

[0034] Specifically, the first side of the pouch (110) is an area where the lithium electrode terminal (132) of the lithium electrode assembly (130), which will be described later, protrudes, and the second side is an area where the negative electrode terminal (121c) and positive electrode terminal (122c) of the electrode element (120) protrude, facing the first side. The third side connects the first side and the second side, and the fourth side faces the third side.

[0035] The electrode element (120) may include a negative electrode assembly (121), a positive electrode assembly (122), and an electrode separator (123).

[0036] Specifically, the electrode element (120) may be formed by winding or stacking two or more sheets of a cathode assembly (121), an anode assembly (122), and an electrode separator (123) formed in a thin or film form. The cathode assembly (121) and the anode assembly (122) may be electrically connected to the outside through a cathode terminal (121c) and an anode terminal (122c).

[0037] The electrode element (120) may have a jelly roll, Z-folding, or stacking form, and for convenience of explanation, the electrode element (120) according to one embodiment of the present invention is illustrated as having a jelly roll form.

[0038] The cathode assembly (121) may include a cathode plate (121a), a cathode active material (121b), and a cathode terminal (121c).

[0039] The cathode plate (121a) may be formed of a metal foil, such as copper or a copper alloy. Alternatively, the cathode plate (121a) may be a metal foil to which a metal plating treatment has been optionally applied. For example, the cathode plate (121a) may comprise a porous copper alloy to facilitate smooth impregnation of the electrolyte.

[0040] A negative active material (121b) can be formed on one side of the negative plate (121a).

[0041] The negative electrode active material (121b) may include a carbon-based active material such as graphite, hard carbon or soft carbon, or a silicon-based composite active material. According to one embodiment of the present invention, the negative electrode active material (121b) may be prepared as a slurry by mixing a conductive material and a binder with a solvent, and may be formed into a multilayer structure of a base coat or a top coat as needed, or layers of different compositions may be sequentially laminated on the negative electrode plate (121a).

[0042] The negative active material (121b) can be applied to one or both sides of the negative plate (121a) through an application device such as a slot die or a comma coater. After the application process, the negative active material (121b) can be set to a predetermined thickness and density through a drying and rolling process.

[0043] A negative terminal (121c) may be formed in the area of ​​the negative plate (121a) where the negative active material (121b) is not formed.

[0044] A portion of the upper surface of the cathode plate (121a) may protrude in the longitudinal direction of the cathode plate (121a) to form a cathode terminal (121c). Specifically, the cathode plate (121a) and the cathode terminal (121c) may be formed integrally.

[0045] As shown in FIG. 2, a plurality of first negative terminals (121c1) can be stacked to form a negative terminal (121c).

[0046] Specifically, as the cathode assembly (121) is wound, a plurality of first cathode terminals (121c1) are stacked together to form a cathode terminal (121c), which can electrically connect the cathode assembly (121) to an external device. The cathode terminal (121c) may include a square shape including angled corners or a round shape.

[0047] The negative electrode assembly (121) is connected to the lithium electrode assembly (130) and the external device (140) through the negative electrode terminal (121c), so that lithium doping can be performed.

[0048] The positive assembly (122) may include a positive plate (122a), a positive active material (122b), and a positive terminal (122c).

[0049] The anode plate (122a) may include a metal foil such as aluminum or an aluminum alloy. For example, the anode plate (122a) may have a porous structure so that the anode active material (122b), the conductive material, and the binder can be effectively fixed.

[0050] An anode active material (122b) can be formed on one side of the anode plate (122a).

[0051] The positive active material (122b) may include a transition metal oxide. At this time, the positive active material (122b) may be mixed with a conductive material and a binder to form a slurry. A carbon-based material may be used as the conductive material, and a polymer material such as PVDF (Polyvinylidene fluoride) may be used as the binder. The positive active material (122b), the conductive material, and the binder may be mixed or stirred in a predetermined ratio according to the storage capacity and purpose of the energy storage device.

[0052] The positive active material (122b) can be applied and dried on one side of the positive plate (122a).

[0053] The positive active material (122b) prepared as a slurry can be uniformly applied onto the positive plate (122a) through an application device such as a slot die or a comma coater. The application thickness of the positive active material (122b) and the application speed of the application device can be adjusted according to the target capacity and electrode uniformity.

[0054] After coating the positive active material (122b), the solvent can be removed during the drying process to solidify the positive active material (122b). Subsequently, if necessary, post-processing steps such as roll pressing can be performed on the fixed positive active material (122b) to improve the density and mechanical stability of the positive assembly (122).

[0055] An anode terminal (122c) may be formed in the region of the anode plate (122a) where the anode active material (122b) is not formed.

[0056] A portion of the upper surface of the positive plate (122a) may protrude in the longitudinal direction of the positive plate (122a) to form a positive terminal (122c). Specifically, the positive plate (122a) and the positive terminal (122c) may be formed integrally. As shown in FIG. 2, a plurality of first positive terminals (122c1) may be stacked to form a positive terminal (122c). The positive terminal (122c) may include a square shape including angled corners or a round shape.

[0057] The positive terminal (122c) can be formed with the same width as the negative terminal (121c) and can be formed spaced apart from each other so as not to overlap.

[0058] Referring to FIGS. 1 and 2, the negative terminal (121c) and the positive terminal (122c) must be formed with a length that can protrude outside the pouch (110) through the second side of the pouch (110).

[0059] The electrode separator (123) can be placed between the negative electrode assembly (121) and the positive electrode assembly (122).

[0060] The electrode separator (123) prevents a short circuit between the negative electrode assembly (121) and the positive electrode assembly (122) and provides a passage for lithium ions to move. The electrode separator (123) can be formed with a larger surface area than the negative electrode assembly (121) and the positive electrode assembly (122).

[0061] The electrode separator (123) may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene, but is not limited thereto.

[0062] A method for manufacturing an energy storage device (100) according to one embodiment of the present invention will be described below through FIGS. 3 to FIGS. 11.

[0063] Referring to FIGS. 3 and 4, a lithium electrode assembly (130) housed within a pouch (110) will be described in detail.

[0064] The lithium electrode assembly (130) can be accommodated inside the pouch (110).

[0065] According to one embodiment of the present invention, the pouch (110) may include a first film (111) and a second film (112) facing each other, and the lithium electrode assembly (130) may be disposed between the first film (111) and the second film (112).

[0066] According to one embodiment of the present invention, a sealing line, i.e., a first sealing portion (S1), is formed along the first side, third side, and fourth side of the pouch (110).

[0067] Along the first sealing portion (S1) shown on the second film (112), the first film (111) and the second film (112) can be sealed together.

[0068] For example, the first film (111) and the second film (112) can be sealed through a heat fusion process in which heat and pressure are applied while in contact, and can also be sealed using a heat sealing bar, ultrasonic sealing, or a combination thereof.

[0069] According to one embodiment of the present invention, the sealing condition can be appropriately set by taking into account the material of the pouch (110), the thickness of the pouch (110), and the arrangement of the components placed inside.

[0070] According to one embodiment of the present invention, a receiving space may be formed inside a pouch (110) to accommodate an electrode element (120), a lithium electrode assembly (130), and an electrolyte.

[0071] Referring to FIG. 4, the lithium electrode assembly (130) may include a copper assembly (131), a lithium electrode terminal (132), and a lithium electrode separator (133).

[0072] The lithium electrode assembly (130) may be a lithium source for doping lithium into the negative electrode assembly (121). The lithium electrode assembly (130) may be manufactured by winding or laminating a copper assembly (131) formed with a predetermined width and length and a lithium electrode separator (133).

[0073] Specifically, the copper assembly (131) may include a copper foil to which lithium metal is attached, and a lithium metal layer may be formed by rolling on one or both sides of the copper foil. The lithium metal formed on the copper assembly (131) may move in the form of lithium ions through the lithium electrode separator (133) and the electrolyte.

[0074] The lithium electrode terminal (132) is a conductive tab electrically connected to the copper assembly (131) and may include a nickel or nickel-plated metal material.

[0075] As shown in FIG. 4, a plurality of first lithium electrode terminals (132a) can be stacked to form a lithium electrode terminal (132). The lithium electrode terminal (132) may include a square shape including angled corners or a round shape.

[0076] The lithium electrode terminal (132) can be extended outward through the first side of the pouch (110). The lithium electrode terminal (132) can be electrically connected to the negative electrode terminal (121c). Specifically, the lithium electrode terminal (132) can form an external circuit required during the lithium doping process together with the negative electrode terminal (121c) via an external device (140).

[0077] The lithium electrode separator (133) can have a larger surface area than the copper assembly (131).

[0078] The lithium electrode separator (133) can prevent electrical connection between copper assemblies (131) while providing an ion conduction pathway.

[0079] The lithium electrode separator (133) may be a porous film having micropores through which lithium ions can pass. The lithium electrode separator (133) may be formed, for example, of polyethylene, polypropylene, or a multilayer structure thereof. The specific area and shape of the lithium electrode separator (133) may be set to correspond to the shape of the lithium electrode assembly (130).

[0080] The coupling relationship between the lithium electrode assembly (130) and the pouch (110) will be described in detail below with reference to FIGS. 5A and 5B. FIG. 5A is a perspective view of the pouch (110) to which the lithium electrode assembly (130) is coupled, and FIG. 5B is a plan view of the pouch (110) to which the lithium electrode assembly (130) is coupled.

[0081] Referring to FIGS. 5A and 5B, a lithium electrode assembly (130) according to one embodiment of the present invention is fixed to a first sealing portion (S1) of a pouch (110). Specifically, since the lithium electrode terminal (132) overlaps with the first sealing portion (S1), it can be fixed between a first film (111) and a second film (112).

[0082] Referring to FIG. 6, an electrode element (120) according to one embodiment of the present invention can be received in an open side of an unsealed pouch (110).

[0083] Specifically, an electrode element (120) can be inserted into the second side of the pouch (110). An electrolyte can be injected into the pouch (110) containing the electrode element (120) including a negative electrode assembly (121) and a positive electrode assembly (122). Thus, the electrode element (120), the lithium electrode assembly (130), and the electrolyte can be contained in the pouch (110).

[0084] Referring to FIG. 7, after accommodating an electrode element (120) and a lithium electrode assembly (130) according to one embodiment of the present invention within a pouch (110), the second side of the pouch (110) that was open can be sealed.

[0085] The first film (111) and the second film (112) can be brought into contact with each other along the second sealing portion (S2) formed on the second side of the pouch (110), and sealed by applying a predetermined temperature and pressure. The method of forming the second sealing portion (S2) is similar to the method of forming the first sealing portion (S1), but is not limited thereto.

[0086] The coupling relationship of the electrode element (120), the lithium electrode assembly (130), and the pouch (110) will be described in detail below with reference to FIGS. 7A and 7B. FIG. 7A is a perspective view of a pouch (110) in which the electrode element (120) and the lithium electrode assembly (130) are coupled, and FIG. 7B is a plan view of a pouch (110) in which the electrode element (120) and the lithium electrode assembly (130) are coupled.

[0087] As shown in FIGS. 7A and 7B, during the formation process of the second sealing portion (S2), the negative terminal (121c) and positive terminal (122c) of the electrode element (120) are arranged to extend outward through the second side of the pouch (110).

[0088] The negative terminal (121c) and the positive terminal (122c) are interposed between the first film (111) and the second film (112) across the area of ​​the second sealing portion (S2) and can be mechanically fixed between the two films by a sealing process. In order to prevent damage to the terminal portion during the fixing process, the thickness, width, and position of the terminals, and the width and pressure of the sealing portion can be appropriately designed so that sufficient sealing performance and electrical reliability are simultaneously ensured.

[0089] In addition, the second sealing portion (S2) seals the space around the electrode terminal, thereby suppressing external moisture or contaminants from entering the pouch (110) and preventing leakage of the electrolyte. Furthermore, by fixing the electrode element (120) at a specific position, the position of the electrode terminal is stabilized, which can reduce the possibility of deformation of the terminal and contact failure during subsequent processes and device operation.

[0090] The lithium doping process will be described in detail below with reference to FIGS. 8A and FIG. 8B. FIG. 8A is a perspective view of a pouch (110) and an external device (140), and FIG. 8B is a top view of a pouch (110) and an external device (140).

[0091] Referring to FIGS. 8A and 8B, an external device (140) can apply current to the electrode element (120) and the lithium electrode assembly (130).

[0092] The negative terminal (121c) of the negative electrode assembly (121) included in the electrode element (120) and the lithium electrode terminal (132) of the lithium electrode assembly (130) can be electrically connected. Electrons flow through an external circuit formed by an external device (140), and lithium ions can move through the electrolyte and the separator.

[0093] The external device (140) may be a power supply that performs current application and monitoring.

[0094] For example, an external device (140) can provide current to the electrode element (120) and the lithium electrode assembly (130) in CC mode or CV mode and monitor the measured voltage or current in real time. If necessary, it can include a temperature sensor and a safety cutoff function to limit overvoltage during the process and control doping termination conditions.

[0095] When current is applied to the external circuit, an oxidation reaction occurs on the surface of the lithium electrode assembly (130), and metallic lithium is oxidized to produce lithium ions.

[0096] The generated electrons move along the external circuit to the negative plate (121a), and lithium ions move through the separator in the electrolyte to the negative plate (121a). The lithium ions that have moved through the electrolyte are inserted into the negative active material (121b) coated on the negative plate (121a). According to one embodiment of the present invention, charge neutralization is achieved within the negative active material (121b) by combining with electrons supplied through the external circuit, thereby storing lithium ions in a stable form.

[0097] Accordingly, doping is achieved by storing lithium ions in the cathode active material (121b) of the cathode assembly (121).

[0098] Since the positive electrode assembly (122) is not electrically connected to the external device (140), no electrons are supplied, and the potential driving direction is set from the lithium electrode (130) to the negative electrode assembly (121), so no lithium ions are stored in the positive electrode active material (122b).

[0099] In the aforementioned process, a solid electrolyte interface (SEI) may be formed on the surface of the cathode assembly (121).

[0100] This is a thin protective film formed by the decomposition of the electrolyte at low potential, which can suppress further decomposition of the electrolyte in subsequent processes and facilitate the selective movement of lithium ions.

[0101] When the potential difference between the negative electrode assembly (121) and the lithium electrode assembly (130) converges to a predetermined reference potential or lower, the operation of the external device (140) is stopped to stop the application of current.

[0102] For example, if the potential difference between the negative electrode assembly (121) and the lithium electrode assembly (130) reaches 0.05V or less, the external device (140) may stop applying current. The condition for stopping the application of current may be individually set according to the purpose of the process and the composition of the electrode element.

[0103] Referring to FIG. 9, a pouch (110) according to one embodiment of the present invention can be rotated or tilted.

[0104] A point spaced apart from the first side of the pouch (110) by a predetermined distance may be defined as a first point (P1), and a point spaced apart from the second side of the pouch (110) by a predetermined distance may be defined as a second point (P2). Additionally, the height between the first point (P1) and the ground (G) may be defined as a first height (h1), and the height between the second point (P2) and the ground (G) may be defined as a second height (h2).

[0105] According to one embodiment of the present invention, the pouch (110) can be rotated or tilted so that the first height (h1) and the second height (h2) of the pouch (110) can have different values.

[0106] By making the first height (h1) and the second height (h2) of the pouch (110) different, the electrolyte inside the pouch (110) can be induced to move in one direction. For example, if the pouch (110) is tilted so that the first height (h1) becomes greater than the second height (h2), the electrolyte inside the pouch (110) can accumulate in the direction of the second point (P2), which is a lower position, due to gravity. By intentionally controlling the position of the electrolyte in this way, it is possible to prevent the electrolyte from being exposed to the outside or leaking near the cutting position described later.

[0107] Referring to FIG. 10, a portion of the pouch (110) can be cut along a first cutting line (CL1) set on the surface of the pouch (110).

[0108] According to one embodiment of the present invention, a first cutting line (CL1) may be formed at a position spaced apart from a first point (P1) by a predetermined distance. As shown in FIG. 9, when the pouch (110) is rotated and the electrolyte is moved toward the second point (P2), the electrolyte may not be present near the first cutting line (CL1). Therefore, even if a part of the pouch (110) is cut along the first cutting line (CL1), the electrolyte contained inside the pouch (110) does not leak out.

[0109] As a method for cutting the pouch (110) along the first cutting line (CL1), cutting using a mechanical cutting blade, thermal cutting using a hot knife, or melting and cutting the pouch (110) by irradiating it with a laser may be used. The cutting process may be performed under predetermined conditions so as not to damage internal components, taking into account the temperature of the electrolyte, the stacked structure and thickness of the pouch (110), and the positions of the electrode element (120) and lithium electrode assembly (130) placed inside.

[0110] When a portion of the pouch (110) is cut, the lithium electrode terminal (132) attached to the first side of the pouch (110) and the lithium electrode assembly (130) electrically connected thereto can be withdrawn and separated from the inside of the pouch (110). Accordingly, the lithium electrode assembly (130) is removed from the pouch (110), and only the electrode element (120) remains inside the pouch (110).

[0111] By using the lithium electrode assembly (130) and pouch (110) configured in this manner, the lithium doping process for the electrode element (120) can be performed directly inside the pouch (110), and then only the lithium electrode assembly (130) can be removed without a separate disassembly and reassembly process. Therefore, an energy storage device (100) can be realized that simplifies the process steps while suppressing the ingress of external foreign matter and electrolyte leakage, and maintaining a stable lithium doping state.

[0112] A display device (100) according to an embodiment of the present invention will be described in detail below with reference to FIGS. 11A and FIG. 11B. FIG. 11A is a perspective view of a display device (100) showing sealing parts (S1, S2, S3), and FIG. 11B is a plan view of a display device (100) showing sealing parts (S1, S2, S3).

[0113] Referring to FIGS. 11A and FIGS. 11B, the open cut surface of the pouch (110) cut along the first cutting line (CL1) can be resealed.

[0114] Specifically, the cut portions of the pouch (110) can be butted together to form a third sealing portion (S3), and sealed through a process similar to that used to form the first sealing portion (S1). The third sealing portion (S3) serves to block the internal electrolyte and electrode element (120) of the pouch (110) from the external environment, thereby preventing the evaporation or leakage of the electrolyte and the inflow of external moisture and contaminants. However, the sealing method is not limited to this.

[0115] The manufactured energy storage device (100) can be determined whether it is defective by measuring its electrical characteristics after the final process.

[0116] For example, the suitability of the lithium doping state and sealing state can be evaluated by checking whether the open circuit voltage measured at the output terminal of the energy storage device (100) falls within a predetermined specification range, for example, a range of about 2.2V to 3.8V. If it falls outside the predetermined range, a screening process related to insufficient lithium doping, internal short circuit, sealing defects, etc., can be performed.

[0117] Hereinafter, a method for manufacturing an energy storage device (200) according to another embodiment of the present invention will be described in detail with reference to FIGS. 12 to 14. FIGS. 12 to 14 are drawings illustrating a method for manufacturing an energy storage device (200) according to another embodiment of the present invention.

[0118] Compared to the energy storage device (100) according to one embodiment of the present invention, the energy storage device (200) according to another embodiment of the present invention has a similar basic lithium doping concept and process flow. However, the energy storage device (200) according to another embodiment of the present invention differs in that it additionally forms a first partial sealing (PS1) inside the pouch (110) to pre-delineate the placement area of ​​the lithium electrode assembly (130), thereby allowing the lithium electrode assembly (130) to be removed more easily and stably thereafter.

[0119] According to another embodiment of the present invention, the first partial sealing (PS1) can separate the area where the lithium electrode assembly (130) is to be placed inside the pouch (110) from the area where the electrode element (120) is placed.

[0120] That is, the first sealing portion (PS1) extends to a predetermined length inside the pouch (110) to define the area where the lithium electrode assembly (130) is located. Additionally, it can serve as a reference line to guide the cutting position and direction during the process of cutting a portion of the pouch (110) along the second cutting line (CL2). Through this, the operation of pulling the lithium electrode assembly (130) out of the pouch (110) can be performed more easily, and unnecessary effects on the electrode element (120) side during the cutting process can be suppressed.

[0121] The first portion sealing (PS1) is configured to partition the placement area of ​​the lithium electrode assembly (130) while allowing the movement of lithium ions. Accordingly, the method of forming and the material of the first portion sealing (PS1) can be varied.

[0122] For example, the first partial sealing (PS1) can be formed by locally fusing the first film (111) and the second film (112) constituting the pouch (110) with heat and pressure, just like the first sealing portion (S1), the second sealing portion (S2), and the third sealing portion (S3). In this case, the sealing width and position can be adjusted so that the electrolyte and lithium ions can move toward the electrode element (120) through the area around the sealing portion or through a fine gap formed in the sealing portion. As another example, the first partial sealing (PS1) can be formed by inserting a separate porous material, such as a porous film, mesh, or nonwoven fabric, into the pouch (110) and then partially fixing it together with the film. Such a porous material can provide an ion channel through which lithium ions can move, while simultaneously performing the function of mechanically stabilizing the position of the lithium electrode assembly (130).

[0123] Referring to FIG. 13, an electrode element (120) is placed on one side based on the first partial sealing (PS1), and a lithium electrode assembly (130) is placed on the other side, and then a lithium doping process can be performed using an external device (140).

[0124] Although not shown in FIG. 13, as described in FIG. 8 to 10, the pouch (110) can be tilted to induce the electrolyte to accumulate toward the area where the electrode element (120) is located.

[0125] Referring to FIG. 14, the second cutting line (CL2) can be set near or outside the first partial sealing (PS1).

[0126] According to one embodiment of the present invention, a portion of the pouch (110) can be cut and the lithium electrode assembly (130) can be drawn out to the outside. Since the first portion sealing (PS1) clearly delineates the placement area of ​​the lithium electrode assembly (130), the cutting position can be precisely set.

[0127] Referring to FIG. 15, after removing the lithium electrode assembly (130), the pouch (110) can be finally sealed by forming a third sealing part (S3) along the first sealing part (PS1) to manufacture an energy storage device (200).

[0128] By forming a new sealing line, a third sealing section (S3), adjacent to the location where the first sealing section (PS1) was formed, the opening from which the lithium electrode assembly (130) was removed can be stably sealed.

[0129] Hereinafter, with reference to FIGS. 16 and FIGS. 17, a method for manufacturing an energy storage device (300) according to another embodiment of the present invention will be described in detail. FIGS. 16 and FIGS. 17 are drawings illustrating a method for manufacturing an energy storage device (300) according to another embodiment of the present invention.

[0130] Compared to an energy storage device (200) according to another embodiment of the present invention, an energy storage device (300) according to yet another embodiment of the present invention is differentiated in that it further provides a second partial sealing (PS2) inside the pouch (110) so as to more effectively suppress leakage of the electrolyte during the process of removing the lithium electrode assembly (130).

[0131] According to another embodiment of the present invention, the energy storage device (300) may include a second partial sealing (PS2) inside the pouch (110).

[0132] The second part sealing (PS2) can function as a blocking structure that minimizes the movement and leakage of the electrolyte between the area where the lithium electrode assembly (130) is placed and the area where the electrode element (120) is placed. That is, the second part sealing (PS2) allows lithium ions to pass through, but restricts the electrolyte itself from flowing out through the area to be cut.

[0133] The second part sealing (PS2) can be formed of a material and structure that allows the movement of lithium ions but inhibits the free flow of solvent molecules or electrolyte.

[0134] For example, the second part sealing (PS2) can be implemented as an ion-conductive porous polymer layer, a gel electrolyte layer, an ion-selective membrane, or a multilayer film having micropores. In this case, by controlling the pore size, thickness, and material combination, even if the diffusion rate of lithium ions is partially reduced, the ion movement required for the lithium doping process can be maintained, while substantially preventing the electrolyte from flowing into or leaking near the second cutting line (CL2) during the step of cutting the pouch (110) or withdrawing the lithium electrode assembly (130).

[0135] The method of forming the second part sealing (PS2) may involve various processes such as heat fusion with the film constituting the pouch (110), bonding, co-extrusion, or insertion of a separate member, but is not limited thereto.

[0136] In another embodiment according to the present invention, the lithium doping process can be performed in the same manner as the aforementioned embodiments.

[0137] Referring to FIG. 17, the advantage of simplifying the final sealing process can also be obtained by sealing only a limited area between the second sealing part (PS2) and the second sealing part (S2).

[0138] Accordingly, according to another embodiment of the present invention, an energy storage device (300) additionally equipped with a second partial sealing (PS2) can provide an energy storage device (300) with improved process reliability and manufacturing yield by simplifying the cutting and sealing process while more effectively suppressing the risk of electrolyte leakage and contamination during the removal process of the lithium electrode assembly (130) after lithium doping.

[0139] It will be obvious to those skilled in the art to which this specification belongs that the present invention is not limited to the aforementioned embodiments and attached drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical concept of this specification.

Claims

1. A step of accommodating a lithium electrode assembly including a lithium electrode terminal protruding toward a first side of a pouch, a negative electrode assembly including a negative electrode terminal, a positive electrode assembly including a positive electrode terminal, and an electrolyte in the pouch; A step of electrically connecting the lithium electrode terminal and the negative electrode terminal to dope the negative electrode assembly with lithium; A step of cutting the pouch along a cutting line formed at a predetermined distance from the first side of the pouch to withdraw the lithium electrode assembly from the pouch; and A method for manufacturing an energy storage device comprising the step of sealing the cut surface of the pouch cut along the above cutting line.

2. In Paragraph 1, The above negative terminal and the above positive terminal protrude to the outside of the pouch through the second side facing the first side, and Prior to the above-mentioned acceptance step, the method further includes the step of sealing a first side of the pouch, a third side connecting the first side and the second side, and a fourth side facing the third side. A method for manufacturing an energy storage device in which the above lithium electrode terminal is sealed to be fixed to the above first side.

3. In Paragraph 1, Prior to the above doping step, A method for manufacturing an energy storage device, further comprising the step of sealing the negative terminal and the positive terminal protruding from the second side opposite to the first side so as to be fixed to the second side.

4. In Paragraph 1, In the above doping step, A method for manufacturing an energy storage device that applies current until the potential of the above-mentioned cathode assembly reaches a predetermined reference potential.

5. In Paragraph 1, Prior to the above cutting step, A method for manufacturing an energy storage device, further comprising the step of rotating the pouch such that the first height between the first side and the ground is greater than the second height between the second side and the ground opposite the first side.

6. In Paragraph 1, In the above cutting step, A method for manufacturing an energy storage device by cutting the pouch by irradiating a laser along the above cutting line.

7. In Paragraph 1, In the above sealing step, The above pouch is a method for manufacturing an energy storage device that is compressed by pressure or heat.

8. In Paragraph 1, The above lithium electrode assembly is a method for manufacturing an energy storage device by winding a copper assembly combined with lithium metal and a lithium electrode separator.

9. An energy storage device manufactured according to the method for manufacturing an energy storage device described in any one of paragraphs 1 through 8, wherein An energy storage device having an output voltage of 2.2V to 3.8V.

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