Expansion detection circuit and battery

Abstract

The utility model relates to the technical field of battery management, and discloses an expansion detection circuit and a battery, and the circuit comprises a conductive module which is arranged on a battery cover plate; the detection piece is connected with the surface of a battery cell of the battery in an attached mode, when the battery expands, the conductive module is electrically connected with the detection piece, and the detection piece outputs a contact signal; the adjusting module is electrically connected with the detection sheet and a test resistor of the battery and is used for receiving the contact signal, adjusting the voltage at the two ends of the test resistor and outputting an adjusted voltage signal; and the control module is connected with the test resistor and is used for receiving the adjusted voltage signal and outputting an expansion signal. The problem that whether expansion and liquid leakage exist in the battery cannot be distinguished from the appearance in the prior art is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, in particular to an expansion detection circuit and a battery. Background Art

[0002] With the widespread use of terminal devices, smartphones have become an indispensable part of our lives.

[0003] However, during the use of a mobile phone, the battery may produce gas inside the cell due to an abnormality. The gas cannot be released inside the sealed cell, causing the battery to expand and increase in volume. When the battery expands to a certain extent, the seal will fail, causing the electrolyte to leak out. The leakage of conductive electrolyte can easily cause a short circuit in the internal circuit of the mobile phone. The large amount of heat or electric sparks generated by the short circuit can cause the battery to catch fire or explode.

[0004] Currently, most mobile phones have a fully sealed structure with non-removable batteries. It is impossible to tell from the appearance whether the battery is swelling or leaking. Therefore, it is extremely important to monitor whether the battery is swelling in real time and take appropriate measures to eliminate fire and explosion after timely detection of inflation and leakage. Utility Model Content

[0005] In view of this, the present invention provides an expansion detection circuit and a battery to solve the problem in the prior art that it is impossible to tell from the appearance whether the battery is expanding or leaking.

[0006] In a first aspect, the present invention provides an expansion detection circuit, the circuit comprising:

[0007] A conductive module, wherein the conductive module is arranged on the battery cover;

[0008] a detection sheet, the detection sheet being in contact with the surface of the battery cell. When the battery expands, the conductive module is electrically connected to the detection sheet, and the detection sheet outputs a contact signal;

[0009] an adjustment module, the adjustment module being electrically connected to the detection piece and the test resistor of the battery, respectively, for receiving a contact signal, adjusting the voltage across the test resistor, and outputting an adjusted voltage signal;

[0010] The control module is connected to the test resistor and is used to receive the regulated voltage signal and output an expansion signal.

[0011] The detection sheet is attached to the surface of the battery cell, and the conductive module is set on the battery cover. When the battery expands, the detection sheet and the conductive module come into contact and output a contact signal. After receiving the contact signal, the adjustment module adjusts the voltage signal at both ends of the test resistor. Therefore, when the control module receives the adjusted voltage signal, it outputs an expansion signal. Furthermore, when the battery expands, it is discovered in time and a corresponding alarm signal is output, without having to distinguish whether the battery is expanding or leaking from the appearance.

[0012] In an optional embodiment, the detection sheet includes:

[0013] a first metal strip, wherein a first end of the first metal strip is connected to a first end of the test resistor, and when the battery expands, a second end of the first metal strip is electrically connected to the conductive module;

[0014] The expansion detection unit has a first end connected to the second end of the test resistor. When the battery expands, the second end of the expansion detection unit is electrically connected to the conductive module, and the expansion detection unit outputs a contact signal. The expansion detection unit is used to detect the expansion degree of the battery.

[0015] In an optional embodiment, the expansion degree detection unit includes:

[0016] A second metal strip, wherein a first end of the second metal strip is electrically connected to a second end of the test resistor, and when the battery expands, the second end of the second metal strip is electrically connected to the conductive module, and the second metal strip outputs a contact signal. The second metal strip is arranged in parallel with the first metal strip.

[0017] In an optional embodiment, the expansion degree detection unit includes:

[0018] a plurality of second metal strips, wherein a first end of each second metal strip is electrically connected to a second end of a test resistor, and when the battery expands to a preset expansion degree, a target second metal strip among the plurality of second metal strips is electrically connected to the conductive module, and the target second metal strip outputs a contact signal;

[0019] The second metal strips are arranged in parallel with the first metal strips, wherein the lengths of the second metal strips are different and the second metal strips are arranged in order of length.

[0020] In an optional embodiment, the conductive module includes:

[0021] at least one conductive strip, wherein when the battery expands, the conductive strip is electrically connected to the first metal strip and the second metal strip, respectively, and the conductive strip is arranged to cross the first metal strip;

[0022] When there are multiple conductive strips, each conductive strip has a different thickness, and each conductive strip is arranged in order of thickness. There is a corresponding relationship between the thickness of the conductive strip and the expansion degree of the battery.

[0023] In an optional embodiment, the adjustment module includes:

[0024] At least one first resistor, a first end of the first resistor is connected to the second end of the test resistor, and a second end of the first resistor is connected to the second metal strip.

[0025] In an optional embodiment, the conductive strip comprises foam coated with a conductive material.

[0026] In an optional embodiment, an oxide layer is provided on the surfaces of the first metal strip and the second metal strip.

[0027] In an optional embodiment, the detection sheet is a flexible circuit board.

[0028] In a second aspect, the present invention provides a battery, which includes the above expansion detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a structural diagram of an expansion detection circuit according to an embodiment of the present utility model;

[0031] Figure 2 This is a schematic diagram of the arrangement of a detection piece in an expansion detection circuit according to an embodiment of the present utility model;

[0032] Figure 3 1 is a schematic diagram of the arrangement of a detection piece in another expansion detection circuit according to an embodiment of the present utility model;

[0033] Figure 4 This is a structural diagram of a detection piece in an expansion detection circuit according to an embodiment of the present utility model;

[0034] Figure 5 1 is a schematic diagram of the arrangement of conductive strips in an expansion detection circuit according to an embodiment of the present utility model;

[0035] Figure 6 is a schematic diagram of an assembly of an expansion detection circuit according to an embodiment of the present utility model;

[0036] Figure 7 is a schematic diagram of the arrangement of conductive strips in another expansion detection circuit according to an embodiment of the present utility model;

[0037] Figure 8 2 is a structural diagram of another expansion detection circuit according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0038] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0039] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal connections between two components; they may refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0041] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] In this regard, an expansion detection circuit is provided in this embodiment, such as Figure 1 、 Figure 2 and Figure 3 As shown, the circuit includes:

[0043] Conductive module 10, the conductive module 10 is arranged on the battery cover;

[0044] Specifically, the conductive module 10 is disposed on the battery cover. Optionally, the conductive module 10 may be a patch with a conductive material.

[0045] The detection piece 20 is bonded to the surface of the battery cell. When the battery expands, the conductive module 10 is electrically connected to the detection piece 20, and the detection piece 20 outputs a contact signal.

[0046] Specifically, the detection sheet 20 is attached to the surface of the battery cell by glue or magnetic attraction. Figure 2 , the detection piece 20 can be electrically connected to the battery protection board, refer to Figure 3 After the battery protection board and battery cell are assembled, the detection sheet 20 is attached to the surface of the battery cell. It should be noted that the battery includes a battery protection board and battery cell. The battery protection board is a circuit board used to protect the battery, for example, by shutting off power in the event of overvoltage during charging, undervoltage during discharging, or overcurrent. Optionally, the detection sheet 20 can be a small circuit board.

[0047] The conductive module 10 and the detection piece overlap in the spatial dimension. Therefore, when the battery expands, the detection piece 20 attached to the surface of the battery cell is electrically connected to the conductive module 10, and the detection piece 20 outputs a contact signal.

[0048] The regulating module 30 is connected to the detection piece 20 and the test resistor R0 of the battery, respectively, and is used to receive the contact signal, adjust the voltage across the test resistor R0, and output the adjusted voltage signal;

[0049] Specifically, the test resistor R0 can be an ID (identification) resistor on the battery protection board. One end of the ID resistor is connected to the negative output terminal of the battery, and the other end is connected to the main controller of the mobile phone through the output connector of the battery protection board. The resistance value of the ID resistor corresponds to the type of battery cell. The main controller of the mobile phone identifies the type of telecommunications by identifying the resistance value of the ID resistor. It should be noted that the test resistor R0 can be a resistor additionally provided on the battery protection board or the detection sheet 20, or the test resistor R0 can also be any resistor on the mobile phone. The adjustment module 30 is used to adjust the resistance output by the test resistor R0, thereby adjusting the voltage across the test resistor R0, and outputting the adjusted voltage signal.

[0050] The control module 40 is connected to the test resistor R0 and is used to receive the adjusted voltage signal and output an expansion signal.

[0051] Specifically, control module 40 can be the main controller of the mobile phone. If test resistor R0 is an ID resistor, the main controller of the mobile phone collects the resistance value of test resistor R0. Therefore, battery expansion detection can be achieved by simply adding detection sheet 20, conductive module 10, and adjustment module 30, thereby significantly reducing costs. Optionally, control module 40 can also be a control chip connected to the main controller of the mobile phone, which is responsible for collecting the voltage signal of test resistor R0.

[0052] It should be noted that the control module 40 includes a resistor, and calculates the voltage across the test resistor R0 by detecting the voltage across the resistor, and outputs a battery expansion signal when the voltage across the test resistor R0 is within a preset range.

[0053] The detection sheet 20 is attached to the surface of the battery cell, and the conductive module 10 is placed on the battery cover. When the battery expands, the detection sheet 20 and the conductive module 10 contact and output a contact signal. After receiving the contact signal, the adjustment module 30 adjusts the voltage signal across the test resistor. Thus, when the control module 40 receives the adjusted voltage signal, it outputs an expansion signal. Furthermore, when the battery expands, a corresponding alarm signal is output after timely detection, eliminating the need to determine whether the battery is expanding or leaking from the appearance. It is worth noting that the methods involved in this embodiment are all mature methods in the existing technology.

[0054] In some optional embodiments, such as Figure 4 As shown, the detection piece 20 includes:

[0055] A first metal strip L1, wherein a first end of the first metal strip is connected to a first end of the test resistor R0, and when the battery expands, a second end of the first metal strip L1 is electrically connected to the conductive module 10;

[0056] Specifically, the first metal strip L1 is a strip-shaped patch made of a conductive material such as metal.

[0057] The expansion detection unit 21 has a first end connected to the second end of the test resistor R0. When the battery expands, the second end of the expansion detection unit 21 is electrically connected to the conductive module 10, and the expansion detection unit 21 outputs a contact signal. The expansion detection unit 21 is used to detect the expansion degree of the battery.

[0058] Specifically, the expansion detection unit 21 is used to detect the degree of battery expansion and outputs specific contact signals, such as a first contact signal and a second contact signal, based on the contact between the expansion detection unit 21 and the conductive module 10. The adjustment module 30 adjusts the voltage across the test resistor R0 based on the received specific contact signals, thereby causing the control module 40 to output the specific expansion degree. Optionally, the expansion detection unit 21 can be a strip-shaped patch made of a conductive material such as metal.

[0059] It is worth noting that the first metal strip L1 and the expansion detection unit 21 are integrated on a circuit board, and the circuit board is attached to the surface of the battery cell.

[0060] In some optional embodiments, the expansion degree detection unit 21 includes:

[0061] A second metal strip L2, wherein a first end of the second metal strip L2 is electrically connected to a second end of the test resistor R0. When the battery expands, a second end of the second metal strip L2 is electrically connected to the conductive module 10, and the second metal strip L2 outputs a contact signal. The second metal strip L2 is arranged parallel to the first metal strip L1.

[0062] Specifically, when the expansion detection unit 21 is a second metal strip L2, the second metal strip L2 and the first metal strip L1 are used to detect battery expansion. In this case, the battery expansion is detected to see if it has reached a preset threshold, for example, 5% of the battery thickness. When the battery expands, the first metal strip L1 and the second metal strip L2 attached to the battery surface are electrically connected to the conductive module 10 to form a loop and output a contact signal. The loop is formed by the first metal strip L1 passing through the conductive module 10 and then returning to the second metal strip L2.

[0063] In some optional embodiments, such as Figure 4 As shown, the expansion detection unit 21 includes:

[0064] a plurality of second metal strips L2, wherein a first end of each second metal strip L2 is electrically connected to a second end of a test resistor R0, and when the battery expands to a preset expansion degree, a target second metal strip among the plurality of second metal strips L2 is electrically connected to the conductive module, and the target second metal strip outputs a contact signal;

[0065] The second metal strips L2 are arranged in parallel with the first metal strips L1 , wherein the lengths of the second metal strips are different and the second metal strips are arranged in order of length.

[0066] Specifically, when the expansion detection unit 21 includes multiple second metal strips L2, each of the multiple second metal strips L2 is used to detect the degree of battery expansion. The preset expansion degree can be, for example, 5%, 7%, or 10% of the battery thickness. The target second metal strip is the second metal strip L2 electrically connected to the conductive module 10 based on the expansion degree. The target second metal strip can be a single second metal strip L2 or multiple second metal strips L2. The contact signal outputted by the target second metal strip depends on the number of target second metal strips.

[0067] refer to Figure 4 , Figure 4This is the case where the expansion detection unit 21 includes two second metal strips L2. Specifically, the second metal strips L2 include L2-1 and L2-2. L2-1 and L2-2 have different lengths, with L2-1 being the same length as the first metal strip L1. The number of second metal strips L2 connected to the conductive module 10 corresponds to the degree of battery expansion. For example, when the battery thickness expands by 5%, only L2-1 connects to the conductive module 10, outputting a first contact signal. When the battery thickness expands by 10%, both L2-1 and L2-2 are connected to the conductive module 10, outputting a second contact signal. Of course, more second metal strips L2 can be provided to detect more detailed expansion conditions, such as 3%, 5%, 7%, and so on, thereby improving the accuracy of battery expansion detection.

[0068] In some optional embodiments, such as Figure 5 、 Figure 6 and Figure 7 As shown, the conductive module 10 includes:

[0069] At least one conductive strip K, which is electrically connected to the first metal strip L1 and the second metal strip L2 when the battery expands, and the conductive strip K is arranged to cross the first metal strip L1;

[0070] When there are multiple conductive strips, each conductive strip K has a different thickness. The conductive strips are arranged in order of thickness. The thickness of the conductive strip K corresponds to the degree of battery expansion. Therefore, depending on the degree of expansion, the number of conductive strips K that come into contact with the second metal strip L2 varies.

[0071] Specifically, the conductive strips K are respectively arranged to cross the first metal strips L1 and the second metal strips L2 , and the conductive strips K arranged according to thickness and the second metal strips L2 arranged according to length have a corresponding relationship according to the expansion degree.

[0072] refer to Figure 6 , the detection piece 20 is attached to the battery, the battery is installed in the battery compartment of the mobile phone, and the conductive strip K is set on the back cover of the mobile phone. When the back cover of the mobile phone covers the battery, refer to Figure 7 Each conductive strip K crosses the first metal strip L1 and the second metal strip L2 respectively but does not contact them. Specifically, each conductive strip K can be set perpendicular to the first metal strip L1. Of course, the conductive strip K can also be set at an angle where it crosses but is not perpendicular to the first metal strip L1.

[0073] refer to Figure 8 When the battery cover covers the battery, the first conductive strip K1 crosses but does not contact the first metal strips L1 and L2-1 respectively, the second conductive strip K2 crosses but does not contact the first metal strips L1, L2-1 and L2-2 respectively, and so on.

[0074] The second metal strips L2 include L2-1, L2-2, ..., and L2-n. The thickness of the first conductive strip K1 through the nth conductive strip Kn is in descending order of thickness, with the first conductive strip K1 being the thickest and the nth conductive strip Kn being the thinnest. Furthermore, the thickness of the first conductive strip K1 through the nth conductive strip Kn is related to the degree of battery expansion. For example, when the battery expands by 5%, the first metal strips L1 and L2-1 of the detection sheet 20 contact the first conductive strip K1, but L2-2 through L2-n are disconnected, ultimately connecting the first metal strips L1 and L2-1. When the battery expands by 10%, the first metal strips L1, L2-1, and L2-2 of the detection sheet 20 contact the second conductive strip K2 and, of course, also the first conductive strip K1. However, L2-3 through L2-n are disconnected, ultimately connecting the first metal strips L1, L2-1, and L2-3, and so on.

[0075] Of course, the thickness of the first conductive strip K1 to the nth conductive strip Kn can also be arranged from thin to thick, that is, the first conductive strip K1 is the thinnest and the nth conductive strip Kn is the thickest. In this case, when the battery thickness expands by 5%, the nth conductive strip Kn is connected to L2-n, ..., L2-2, and L2-1.

[0076] It should be noted that when the battery thickness expands by 10%, although the first conductive strip K1 is in contact with the first metal strips L1 and L2-1, it is equivalent to a wire and can be ignored.

[0077] In some optional embodiments, such as Figure 8 As shown, the adjustment module 30 includes:

[0078] At least one first resistor R1 , wherein a first end of the first resistor R1 is connected to a second end of the test resistor R0 , and a second end of the first resistor R1 is connected to the second metal strip L2 .

[0079] Specifically, refer to Figure 8 The first resistor R1 includes R1-1, R1-2, ..., and R1-n. When the first metal strip L1 is connected to L2-1, it is equivalent to connecting R1-1 in parallel with the test resistor R0. When the first metal strip L1 is connected to L2-1 and L2-2, it is equivalent to connecting R1-1 and R1-2 in parallel with the test resistor R0, and so on. In other words, depending on the degree of battery thickness expansion, the resistance value of the resistor connected in parallel across the test resistor R0 varies, and thus the voltage across the test resistor R0 varies.

[0080] A first end of the test resistor R0 is connected to the negative output end, and a second end of the test resistor R0 is connected to the control module 40 . It is worth noting that the negative output end is connected to the negative electrode of the control module 40 .

[0081] For example, the thickness relationship between the first conductive strip K1 and the nth conductive strip Kn is from thick to thin. When the thickness of the battery expands by 5%, the first metal strip L1 and L2-1 are connected. At this time, R1-1 is connected in parallel with the test resistor R0. Specifically, the first resistor R1 can be set to 10KΩ, and the test resistor R0 is also 10KΩ. The resistance at this time is Then R = 5KΩ. When the battery thickness expands by 10%, the first metal strips L1, L2-1 and L2-2 are connected, and the resistance at this time is Then R = 3.333 kΩ. That is, the more the battery expands, the smaller the resistance across test resistor R0 becomes, and the smaller the voltage signal output to control module 40 becomes. Control module 40 detects the battery expansion percentage based on the magnitude of the received voltage signal, thereby accurately outputting the battery's expansion status.

[0082] If the thickness of the first conductive strip K1 through the nth conductive strip Kn increases from thin to thick, the more the battery expands, the greater the resistance across the test resistor R0 and the larger the voltage signal output to the control module 40. The control module 40 detects the battery expansion percentage based on the magnitude of the received voltage signal, thereby accurately outputting the battery expansion status.

[0083] Optionally, the first resistor R1 may be replaced by a plurality of resistors connected in series or in parallel.

[0084] In some optional embodiments, an oxide layer is provided on the surfaces of the first metal strip L1 and the second metal strip L2.

[0085] Specifically, the surfaces of the first metal strip L1 and the second metal strip L2 are provided with a conductive metal material, and the surfaces of the metal materials are gold-plated to prevent oxidation, thereby improving the stability of detection.

[0086] In some optional embodiments, the detection sheet 20 is a flexible circuit board.

[0087] Specifically, the detection piece 20 may be a flexible printed circuit (FPC), and may also be made by laminating the first metal strip L1 and the second metal strip L2 on a flexible base.

[0088] In this embodiment, the present invention provides a battery having a protective plate electrically connected to a detection plate 20, specifically via a test resistor R0 in the battery protective plate. The detection plate 20 is attached to the surface of the battery cell. A regulation module 30 is disposed on the protective plate, and a conductive module 10 is disposed on the battery cover. The control module 40 can be specifically a control device for a terminal device connected to the battery. Consequently, when the control module receives a regulated voltage signal, it outputs an expansion signal. Consequently, when battery expansion is detected, a corresponding alarm signal is output, eliminating the need to visually determine whether the battery is leaking.

[0089] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. An expansion detection circuit, characterized in that: The circuit comprises: A conductive module, wherein the conductive module is arranged on the battery cover; a detection sheet, the detection sheet being in contact with the surface of the battery cell. When the battery expands, the conductive module is electrically connected to the detection sheet, and the detection sheet outputs a contact signal; an adjustment module, the adjustment module being electrically connected to the detection piece and the test resistor of the battery, respectively, and configured to receive the contact signal, adjust the voltage across the test resistor, and output an adjusted voltage signal; A control module is connected to the test resistor and is used to receive the adjusted voltage signal and output an expansion signal.

2. The circuit according to claim 1, wherein: The detection piece includes: a first metal strip, wherein a first end of the first metal strip is connected to a first end of the test resistor, and when the battery expands, a second end of the first metal strip is electrically connected to the conductive module; An expansion detection unit, wherein a first end of the expansion detection unit is connected to a second end of the test resistor, and when the battery expands, a second end of the expansion detection unit is electrically connected to the conductive module, and the expansion detection unit outputs a contact signal, wherein the expansion detection unit is used to detect the degree of expansion of the battery.

3. The circuit according to claim 2, characterized in that The expansion degree detection unit includes: A second metal strip, wherein a first end of the second metal strip is electrically connected to a second end of the test resistor, and when the battery expands, a second end of the second metal strip is electrically connected to the conductive module, the second metal strip outputs a contact signal, and the second metal strip is arranged parallel to the first metal strip.

4. The circuit according to claim 2, characterized in that The expansion degree detection unit includes: a plurality of second metal strips, wherein a first end of each second metal strip is electrically connected to a second end of the test resistor, and when the battery expands to a preset expansion degree, a target second metal strip among the plurality of second metal strips is electrically connected to the conductive module, and the target second metal strip outputs a contact signal; The second metal strips are arranged in parallel with the first metal strips, wherein the second metal strips have different lengths and are arranged in order of length.

5. The circuit according to any one of claims 3 or 4, characterized in that: The conductive module includes: at least one conductive strip, wherein when the battery expands, the conductive strip is electrically connected to the first metal strip and the second metal strip, respectively, and the conductive strip is arranged to cross the first metal strip; When there are multiple conductive strips, each conductive strip has a different thickness, and each conductive strip is arranged in order of thickness. There is a corresponding relationship between the thickness of the conductive strip and the expansion degree of the battery.

6. The circuit according to claim 5, characterized in that The adjustment module includes: At least one first resistor, wherein a first end of the first resistor is connected to a second end of the test resistor, and a second end of the first resistor is connected to the second metal strip.

7. The circuit according to claim 6, characterized in that The conductive strip includes foam coated with a conductive material.

8. The circuit according to claim 7, characterized in that An oxide layer is provided on the surfaces of the first metal strip and the second metal strip.

9. The circuit according to claim 8, characterized in that The detection sheet is a flexible circuit board.

10. A battery, characterized in that: The battery comprises the expansion detection circuit according to any one of claims 1 to 9.

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