Secondary battery, vent detection system of secondary battery

Abstract

The present invention relates to a secondary battery and a vent detection system for a secondary battery. Specifically, it relates to a secondary battery and a vent detection system for a secondary battery that detects vents occurring at the cell level of a pouch-type secondary battery at an early stage, allowing the user to identify and replace the battery before performance and safety issues arise, thereby minimizing damage to life and property. A secondary battery according to the present invention comprises an electrode assembly, a pouch housing the electrode assembly, and a flexible flat cable (FFC) provided along the circumference of the pouch and serving as a means for detecting whether a vent has occurred in the pouch.

Description

Technology Field

[0001] The present invention relates to a secondary battery and a vent detection system for a secondary battery. Specifically, it relates to a secondary battery and a vent detection system for a secondary battery that detects vents occurring at the cell level of a pouch-type secondary battery at an early stage, allowing the user to identify and replace the battery before performance and safety issues arise, thereby minimizing damage to life and property. Background Technology

[0002] Unlike primary batteries that cannot be recharged, secondary batteries refer to batteries that can be charged and discharged. They are widely used in small electronic devices such as mobile phones and laptops, as well as large products requiring high output such as electric vehicles, and in Energy Storage Systems (ESS) and backup power storage devices that store surplus generated power or renewable energy.

[0003] These secondary batteries are classified according to the shape of the battery case into cylindrical and prismatic secondary batteries, in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch-type case made of aluminum laminate sheet.

[0004] Looking at the general structure and manufacturing process of secondary batteries, an electrode assembly is housed inside a battery case, an electrolyte is injected, and the battery case is sealed to achieve a complete seal. Specifically, in the case of a pouch-type secondary battery, an electrode assembly is housed inside a pouch and an electrolyte is injected, after which the perimeter of the pouch is sealed by heat compression.

[0005] Meanwhile, in rechargeable batteries, there may be instances where these sealing areas separate, causing the battery case seal to be released; this phenomenon is referred to as a vent. When a vent occurs in a rechargeable battery, the electrolyte injected inside the case leaks to the outside, degrading battery performance or rendering it unusable, thereby undermining product reliability. Furthermore, when a vent occurs, the electrolyte may vaporize or reactive gases generated internally may leak out of the battery case, potentially leading to ignition or explosion and posing a serious threat to user safety.

[0006] Therefore, while it is best to prevent such vents from occurring in the first place, they may inevitably develop due to manufacturing defects or the usage environment; in such cases, it is important to detect them early and replace the unit.

[0007] However, unlike prismatic secondary batteries, it is relatively difficult to detect vents at the cell level in pouch-type secondary batteries. In particular, when secondary batteries are used in electric vehicles or ESS installed in buildings, unlike small electronic devices, users cannot be located close to them, so there is a problem in that it is difficult to easily detect vents through sound, smell, etc.

[0008] Accordingly, research and development regarding secondary batteries and secondary battery vent detection systems are necessary to resolve the aforementioned problems. The problem to be solved

[0009] The present invention has been devised to solve the above-mentioned problems, and the objective of the present invention is to provide a secondary battery and a secondary battery vent detection system that can minimize damage to life and property by detecting vents occurring at the cell level of a pouch-type secondary battery at an early stage, thereby allowing the user to identify and replace the battery before performance and safety issues arise. means of solving the problem

[0010] A secondary battery according to the present invention comprises an electrode assembly, a pouch housing the electrode assembly, and a flexible flat cable (FFC) provided along the circumference of the pouch and serving as a means for detecting whether a vent has occurred in the pouch.

[0011] The pouch includes a folding portion in which a pouch film is folded to form an upper pouch and a lower pouch, and a sealing portion in which the inner side of the sealing surface of the upper pouch and the inner side of the sealing surface of the lower pouch are sealed to each other, and a flexible flat cable may be provided in the sealing portion.

[0012] The flexible flat cable is bonded to the sealing portion of the pouch and can be stretched together with the pouch when venting occurs in the pouch.

[0013] The flexible flat cable can be joined at least one location between the inner side of the sealing surface of the upper pouch and the lower pouch, or the outer side of the sealing surface of the upper pouch and the lower pouch.

[0014] A flexible flat cable can be bonded to at least one of the sealing surfaces of the upper pouch and the lower pouch.

[0015] The flexible flat cable can be uniformly bonded to the entire sealing surface of the upper pouch or the lower pouch.

[0016] The pouch has one folding section and three sealing sections formed along the perimeter of the pouch, and a flexible flat cable can be provided along the three sealing sections formed in the pouch.

[0017] The flexible flat cable is provided as a single cable that is continuously connected along three sealing portions formed in the pouch, and includes at least one bending portion between one end terminal and the other end terminal, and can be provided along the sealing surface of the upper pouch and the sealing surface of the lower pouch.

[0018] The flexible flat cable is provided in multiple numbers by being disconnected at at least one of the three sealing portions formed in the pouch, and each flexible flat cable includes at least one bending portion between one end terminal and the other end terminal, and can be provided along the sealing surface of the upper pouch and the sealing surface of the lower pouch.

[0019] A flexible flat cable may include a thin-film conductive layer provided in a pouch and an insulating layer provided to cover the conductive layer.

[0020] The conductive layer can be formed from either copper foil (Cu foil) or aluminum foil (Al foil).

[0021] A vent detection system for a secondary battery according to the present invention comprises an electrode assembly, a pouch housing the electrode assembly, a secondary battery including a flexible flat cable (FFC) provided along the perimeter of the pouch and serving as a means for detecting whether a vent has occurred in the pouch, and a cell module controller (CMC) connected to the secondary battery. The cell module controller is connected to the flexible flat cable of the secondary battery and detects a change in resistance caused by the stretching of the flexible flat cable to determine whether a vent has occurred in the secondary battery.

[0022] The cell module controller can determine that a vent has occurred in the secondary battery if the resistance of the flexible flat cable increases. Effects of the invention

[0023] The secondary battery according to the present invention comprises an electrode assembly, a pouch housing the electrode assembly, and a flexible flat cable (FFC) provided along the circumference of the pouch and serving as a means for detecting whether a vent has occurred in the pouch. Accordingly, vents occurring at the cell unit of the pouch-type secondary battery are detected early, allowing the user to identify and replace the battery before performance and safety issues arise, thereby minimizing damage to life and property. Brief explanation of the drawing

[0024] Figure 1 is a diagram illustrating a conventional secondary battery and a cell module controller. FIG. 2 is a plan view illustrating a secondary battery according to Example 1 of the present invention. FIG. 3 is a perspective view illustrating a pouch of a secondary battery according to Example 1 of the present invention. FIG. 4 is a perspective view illustrating a pouch of a secondary battery according to Embodiment 1 of the present invention having a flexible flat cable provided therein. FIG. 5 is a cross-sectional view illustrating a flexible flat cable provided in the sealing portion of a pouch in a secondary battery according to Example 1 of the present invention. FIG. 6 is a perspective view illustrating a secondary battery according to Embodiment 1 of the present invention having one flexible flat cable. FIG. 7 is a perspective view illustrating a plurality of flexible flat cables provided in a secondary battery according to Embodiment 1 of the present invention. FIG. 8 is a diagram illustrating a vent detection system of a secondary battery according to Embodiment 2 of the present invention. Specific details for implementing the invention

[0025] Hereinafter, preferred embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited or restricted by the following embodiments.

[0026] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or that may unnecessarily obscure the essence of the invention have been omitted. Furthermore, when assigning reference numerals to the components of each drawing in this specification, identical or similar reference numerals are assigned to identical or similar components throughout the entire specification.

[0027] Furthermore, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0029] Example 1

[0030] FIG. 1 is a drawing illustrating a conventional secondary battery and a cell module controller. FIG. 2 is a plan view illustrating a secondary battery according to Embodiment 1 of the present invention. FIG. 3 is a perspective view illustrating a pouch of a secondary battery according to Embodiment 1 of the present invention. FIG. 4 is a perspective view illustrating a flexible flat cable provided in the pouch of a secondary battery according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view illustrating a flexible flat cable provided in the sealing portion of the pouch of a secondary battery according to Embodiment 1 of the present invention. FIG. 6 is a perspective view illustrating a single flexible flat cable provided in a secondary battery according to Embodiment 1 of the present invention. FIG. 7 is a perspective view illustrating a plurality of flexible flat cables provided in a secondary battery according to Embodiment 1 of the present invention.

[0031] Referring to FIG. 2, a secondary battery (10) according to Embodiment 1 of the present invention comprises an electrode assembly (not shown in the drawing), a pouch (100), and a flexible flat cable (200) (FFC). The electrode assembly is housed inside the pouch (100), and the flexible flat cable (200) is provided along the circumference of the pouch (100) as a means for detecting whether a vent occurs in the pouch (100). Accordingly, when a vent occurs around the circumference of the pouch (100), the flexible flat cable (200) is stretched together with the pouch (100), causing a change in resistance and current, thereby enabling early detection of a vent occurring in the cell unit of the pouch-type secondary battery (10). In this way, if the user detects the vent of the secondary battery (10) early, they can identify and replace it before any performance or safety issues arise with the secondary battery (10), thereby preventing ignition or explosion accidents of the secondary battery (10) and minimizing damage to life and property. The components of the secondary battery (10) will be described in detail below.

[0032] First, the electrode assembly may include a positive plate with an active material coated on a positive current collector, a negative plate with an active material coated on a negative current collector, a separator interposed between the positive plate and the negative plate, and electrode tabs attached to the positive plate and the negative plate. The shape of the electrode assembly may be a suitable shape that can be stored inside a pouch (100), such as a jelly-roll type or a stack type. As such, the materials and shapes for the detailed configurations of the electrode assembly included in Example 1 of the present invention may be selected from those generally practiced in the industry.

[0033] Next, referring to FIGS. 3 and 4, the pouch (100) is formed by folding the pouch film in the folding section (110) to form an upper pouch (100-1) and a lower pouch (100-2), and the inner side of the sealing surface of the upper pouch (100-1) and the inner side of the sealing surface of the lower pouch (100-2) can be sealed together in the sealing section (120). Additionally, a flexible flat cable (200), which will be described later, may be provided in the sealing section (120). That is, since vents mainly occur in the sealing section (120) of the pouch (100) formed by the folding method, by providing a flexible flat cable (200), which is a vent detection means, in the inner side of the sealing surface of the sealing section (120), vents occurring in the cell unit of the secondary battery (10) can be effectively detected.

[0034] Looking in detail at the structure and manufacturing process of the pouch (100), first, the pouch film can be formed by laminating multiple layers made of materials such as polypropylene (PP), aluminum foil (Al foil), nylon, and polyethylene terephthalate (PET), and after inserting the pouch (100) film formed in this way into a press, pressure is applied with a punch to stretch it, thereby forming a cup portion that accommodates an electrode assembly.

[0035] In addition, one side of the pouch film is folded using a folding device. When the pouch (100) is manufactured in this manner, one folding section (110) and three sealing sections (120) may be formed along the circumference of the pouch (100). In the case of the secondary battery (10) according to Embodiment 1 of the present invention, a flexible flat cable (200) may be provided along the three sealing sections (120) formed in the pouch (100). When the pouch (100) is manufactured in this folding manner, there is an advantage in that the corners requiring sealing can be reduced to improve the process speed and the trimming process can be reduced. In addition, if the flexible flat cable (200) is provided in all three sealing sections (120), it becomes possible to detect any vent that occurs in any of the three sealing sections (120).

[0036] Next, with reference to FIGS. 4 to 7, a flexible flat cable (200) according to Embodiment 1 of the present invention will be described in detail.

[0037] As illustrated in FIGS. 4 and 5, the flexible flat cable (200) may include a conductive layer (210) and an insulating layer (220), and the conductive layer (210) in the form of a thin film may be provided in a pouch (100), and the insulating layer (220) may be provided to cover the conductive layer (210). In this case, when the conductive layer (210) is provided in the form of a thin film, the conductive layer (210) can be physically changed by even a very small force, thereby enabling effective detection of the vent of the secondary battery (10).

[0038] Meanwhile, the conductive layer (210) may be formed from either copper foil (Cu foil) or aluminum foil (Al foil), which have excellent conductivity and are easy to manufacture in the form of a thin film, but is not necessarily limited thereto and may be formed from various conductive metal thin films. Additionally, the insulating layer (220) may be formed from various polymer compounds capable of physically protecting and insulating the conductive layer (210).

[0039] A flexible flat cable (200) is bonded to the sealing portion (120) of a pouch (100) and can be stretched together with the pouch (100) when a vent occurs in the pouch (100). That is, when a vent occurs in the sealing portion (120) of the pouch (100), the sealing portion (120) of the pouch (100) opens up, and the flexible flat cable (200) bonded to the sealing portion (120) of the pouch (100) is also stretched together with the pouch (100). At this time, the thickness of the conductive layer (210) becomes thinner and the length becomes longer, so the resistance of the conductive layer (210) increases, and the current flowing through the conductive layer (210) decreases. Therefore, by detecting these changes in resistance and current, it is possible to know whether a vent occurs in the pouch (100).

[0040] The flexible flat cable (200) can be bonded to the pouch (100) by first loading the conductive layer (210) into the pouch (100) and then printing or attaching the insulating layer (220) on top, but is not necessarily limited to this and can be bonded to the pouch (100) in various other mass-producible ways.

[0041] Referring to FIGS. 4 and 5, the location where the flexible flat cable (200) is joined can be specifically examined. The flexible flat cable (200) can be joined at least one of the inner side of the sealing surface of the upper pouch (100-1) and the lower pouch (100-2) or the outer side of the sealing surface of the upper pouch (100-1) and the lower pouch (100-2). Each of the upper pouch (100-1) and the lower pouch (100-2) has a sealing surface. The inner side of the sealing surface refers to the area where the upper pouch (100-1) and the lower pouch (100-2) face each other and are joined or sealed, and the outer side of the sealing surface refers to the outer side of the sealing portion (120) of the sealed pouch (100), which is located opposite to the inner side of the sealing surface. When sealing the pouch (100) by a heat compression method, the inner side of the sealing surface is sealed by applying pressure to the outer side of the sealing surface of the pouch (100).

[0042] The flexible flat cable (200) according to Embodiment 1 of the present invention may be bonded only to the inner side of the sealing surface of the upper pouch (100-1) and the lower pouch (100-2), or it may be bonded only to the outer side of the sealing surface of the upper pouch (100-1) and the lower pouch (100-2) (see FIG. 4 and 5), or it may be bonded to both the inner side and the outer side of the sealing surface of the upper pouch (100-1) and the lower pouch (100-2). When the flexible flat cable (200) is bonded to the outer side of the sealing surface, the secondary battery (10) according to the present invention can be manufactured without significantly changing the existing pouch (100) sealing process and equipment, making it economical. Furthermore, since conditions such as heat resistance and pressure resistance are not significantly required for the flexible flat cable (200), there is an advantage that the flexible flat cable (200) can be easily manufactured. On the other hand, when a flexible flat cable (200) is bonded to the inner side of the sealing surface, it can react more sensitively to physical changes in the sealing portion (120) of the pouch (100) than to the outer side of the sealing surface, thereby allowing for early detection of even minute vents. However, FIGS. 4 and 5 only illustrate the case where the flexible flat cable (200) is bonded to the outer side of the sealing surface, and the case where it is bonded to the inner side of the sealing surface can also be understood by referring to FIGS. 4 and 5 and the above description.

[0043] The flexible flat cable (200) can be bonded to at least one of the sealing surfaces of the upper pouch (100-1) and the lower pouch (100-2). That is, the flexible flat cable (200) may be bonded only to the sealing surface of the upper pouch (100-1), may be bonded only to the sealing surface of the lower pouch (100-2), or may be bonded to both the sealing surface of the upper pouch (100-1) and the sealing surface of the lower pouch (100-2). In particular, as shown in FIGS. 4 and 5, when bonded to both the sealing surface of the upper pouch (100-1) and the sealing surface of the lower pouch (100-2), vents occurring on both sides of the upper pouch (100-1) and the lower pouch (100-2) can be effectively detected.

[0044] Additionally, the flexible flat cable (200) can be uniformly bonded to the entire sealing surface of the upper pouch (100-1) or the lower pouch (100-2). This allows for the detection of changes in resistance and current, and the detection of whether a vent has occurred, even if a portion of the conductive layer (210) is separated from the pouch (100).

[0045] Next, with reference to FIGS. 4, FIGS. 6 and FIGS. 7, we examine the structure of the flexible flat cable (200) and the form in which the flexible flat cable (200) is provided in the pouch (100).

[0046] As illustrated in FIGS. 4 and 6, the flexible flat cable (200) is provided as a single cable that is continuously connected along three sealing portions (120) formed in the pouch (100), and can be integrally provided along the sealing surface of the upper pouch (100-1) and the sealing surface of the lower pouch (100-2) by including at least one bend portion between one end terminal and the other end terminal formed to be connected to another external circuit.

[0047] That is, a flexible flat cable (200) starting from one end terminal connected to an external circuit is provided along the sealing surface of the upper pouch (100-1), then folded toward the lower pouch (100-2), and then provided along the sealing surface of the lower pouch (100-2), and can be connected to the external circuit again at the other end terminal. In this way, by forming the entire sealing surface of the upper pouch (100-1) and the lower pouch (100-2) into a single cable, the manufacturing and attachment of the flexible flat cable (200) becomes easy, and since the flexible flat cable (200) is attached at once to all sealing parts (120) where vents may occur in the secondary battery (10), vents can be effectively detected.

[0048] In addition, the flexible flat cable (200) may be provided in multiple numbers by being disconnected from at least one of the three sealing portions (120) formed in the pouch (100), and may be provided along the sealing surface of the upper pouch (100-1) and the sealing surface of the lower pouch (100-2) by including at least one bending portion between one end terminal and the other end terminal of each flexible flat cable (200).

[0049] For example, referring to FIG. 7, two flexible flat cables (200) may be provided, one provided in a sealing portion (120) where the electrode tab is exposed, and the other provided to be continuously connected along the remaining two sealing portions (120). When multiple flexible flat cables (200) are provided in this manner, the flexible flat cables (200) can be manufactured with various materials and shapes depending on the location of provision, and it is possible to determine which sealing portion (120) among the multiple sealing portions (120) formed in the pouch (100) of the secondary battery (10) has a vent.

[0051] Example 2

[0052] FIG. 8 is a diagram illustrating a vent detection system of a secondary battery according to Embodiment 2 of the present invention.

[0053] Embodiment 2 of the present invention differs from Embodiment 1 in that it further includes a cell module controller and is a system for detecting whether a vent has occurred in the secondary battery (10) according to Embodiment 1. Common details with Embodiment 1 will be omitted as much as possible, and Embodiment 2 will be described focusing on the differences. That is, it is obvious that if details not explained in Embodiment 2 are needed, they can be considered as details of Embodiment 1.

[0054] Referring to FIG. 8, a vent detection system for a secondary battery according to Embodiment 2 of the present invention includes a secondary battery (10) and a cell module controller (20) (Cell Module Controller, CMC) connected to the secondary battery (10), and the secondary battery (10) can be understood as being the same as described in Embodiment 1.

[0055] As illustrated in FIG. 1, a conventional cell module controller is connected to an electrode tab to measure the voltage of a cell of a secondary battery. However, the cell module controller (20) according to Embodiment 2 of the present invention is connected to a flexible flat cable (200) of a secondary battery (10) to detect a change in resistance caused by the stretching of the flexible flat cable (200), thereby determining whether a vent has occurred in the secondary battery (10). In this way, a vent occurring at the cell unit of a pouch-type secondary battery (10) can be detected early. In particular, even in usage environments where it is difficult for a user to detect a vent through visual observation, sound, smell, etc., such as when used in a large-capacity power storage device or an electric vehicle, the vent of the secondary battery (10) can be effectively detected, thereby minimizing damage to the user's life and property.

[0056] The cell module controller (20) can determine that a vent has occurred in the secondary battery (10) when the resistance of the flexible flat cable (200) increases. That is, by determining whether a vent has occurred through minute changes in resistance and current, the vent can be detected more quickly and accurately than by methods such as sound, smell, or visual observation.

[0057] In addition, the cell module controller (20) can generate an alarm signal to the user when it detects a vent, or control the charging and discharging of the secondary battery (10).

[0058] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0059] 10: Secondary battery 20: Cell Module Controller 100: Pouch 100-1: Upper pouch 100-2: Lower pouch 110: Folding part 120: Sealing part 200: Flexible flat panel cable 210: Challenge Floor 220: Insulating layer

Claims

Claim 1 A secondary battery comprising: an electrode assembly; a pouch housing the electrode assembly inside; and a flexible flat cable (FFC) provided along the circumference of the pouch and serving as a means for detecting whether a vent has occurred in the pouch, wherein the pouch includes a folding portion in which a pouch film is folded to form an upper pouch and a lower pouch; and a sealing portion in which the inner side of the sealing surface of the upper pouch and the inner side of the sealing surface of the lower pouch are sealed to each other, and the flexible flat cable is provided along the sealing portion. Claim 2 delete Claim 3 A secondary battery according to claim 1, wherein the flexible flat cable is bonded to the sealing portion of the pouch and is stretched together with the pouch when a vent occurs in the pouch. Claim 4 A secondary battery according to claim 1, wherein the flexible flat cable is joined at least one of the inner side of the sealing surface of the upper pouch and the lower pouch or the outer side of the sealing surface of the upper pouch and the lower pouch. Claim 5 A secondary battery according to claim 1, wherein the flexible flat cable is bonded to at least one of the sealing surface of the upper pouch and the sealing surface of the lower pouch. Claim 6 A secondary battery according to claim 1, wherein the flexible flat cable is uniformly bonded to the entire sealing surface of the upper pouch or the sealing surface of the lower pouch. Claim 7 A secondary battery according to claim 1, wherein the pouch has one folding portion and three sealing portions formed along the circumference of the pouch, and the flexible flat cable is provided along the three sealing portions formed in the pouch. Claim 8 A secondary battery according to claim 7, wherein the flexible flat cable is provided as a single cable that is continuously connected along three sealing portions formed in the pouch, and includes at least one bending portion between one end terminal and the other end terminal, and is provided along the sealing surface of the upper pouch and the sealing surface of the lower pouch. Claim 9 A secondary battery according to claim 7, wherein the flexible flat cable is provided in a plurality of portions by being disconnected at at least one of the three sealing portions formed in the pouch, and each of the flexible flat cables includes at least one bend portion between one end terminal and the other end terminal, and is provided along the sealing surface of the upper pouch and the sealing surface of the lower pouch. Claim 10 In claim 1, the flexible flat cable comprises a thin-film conductive layer provided in the pouch; and an insulating layer provided to cover the conductive layer, forming a secondary battery. Claim 11 A secondary battery according to claim 10, wherein the conductive layer is formed from either copper foil (Cu foil) or aluminum foil (Al foil). Claim 12 A secondary battery according to claim 1; and a cell module controller (CMC) connected to the secondary battery, wherein the cell module controller is connected to a flexible flat cable of the secondary battery and detects a change in resistance due to the stretching of the flexible flat cable to determine whether a vent has occurred in the secondary battery. Claim 13 A vent detection system for a secondary battery according to claim 12, wherein the cell module controller determines that a vent has occurred in the secondary battery when the resistance of the flexible flat cable increases.

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