Flexible battery and electronic device

Abstract

The application discloses a flexible battery and an electronic device, and belongs to the technical field of batteries. The flexible battery comprises a first flexible packaging layer (F100), a plurality of battery cells (100) and a second flexible packaging layer (F200) which are arranged in layers. The plurality of battery cells (100) are arranged on one side of the first flexible packaging layer (F100) and are arranged at intervals along a first direction (H1). The second flexible packaging layer (F200) comprises a convex part (F301) covering the battery cells (100) and a concave part (F302) located between adjacent battery cells (100). The elastic modulus of the first flexible packaging layer (F100) is greater than that of the second flexible packaging layer (F200). The flexible battery can improve the bending resistance of the flexible battery.

Description

Technical Field

[0001] This disclosure relates to the field of battery technology, and more specifically, to a flexible battery and an electronic device. Background Technology

[0002] The edges of flexible batteries are prone to micro-cracks due to bending, which can lead to encapsulation failure. Flexible batteries are prone to leakage, swelling and bulging, and may pose safety hazards.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a flexible battery and electronic device that improves the bending resistance of the flexible battery.

[0005] According to one aspect of this disclosure, a flexible battery is provided, comprising:

[0006] First flexible encapsulation layer;

[0007] Multiple battery cells are disposed on one side of the first flexible encapsulation layer and spaced apart along the first direction;

[0008] The second flexible encapsulation layer includes a protruding portion covering the battery cell and a recessed portion located between adjacent battery cells;

[0009] The elastic modulus of the first flexible encapsulation layer is greater than that of the second flexible encapsulation layer.

[0010] According to one embodiment of this disclosure, the elastic modulus of the first flexible encapsulation layer is 6 to 11 times that of the elastic modulus of the second flexible encapsulation layer.

[0011] According to one embodiment of this disclosure, the elastic modulus of the first flexible encapsulation layer is in the range of 180 GPa to 220 GPa.

[0012] According to one embodiment of this disclosure, the elastic modulus of the second flexible encapsulation layer is in the range of 20 GPa to 30 GPa.

[0013] According to one embodiment of this disclosure, the spacing between two adjacent battery cells is not less than the thickness of the battery cell.

[0014] According to one embodiment of this disclosure, the battery cell includes a battery cell body and positive and negative tabs located at both ends of the battery cell body; the positive and negative tabs are bent to the surface of the battery cell body;

[0015] The flexible battery further includes a flexible conductive layer extending along the first direction; the flexible conductive layer is at least partially sandwiched between the first flexible encapsulation layer and the second flexible encapsulation layer, and is electrically connected to the positive electrode tab and the negative electrode tab.

[0016] According to one embodiment of this disclosure, the flexible conductive layer includes a first flexible conductive strip and a second flexible conductive strip extending along a first direction; the first flexible conductive strip is electrically connected to the positive electrode tab of each of the battery cells; and the second flexible conductive strip is electrically connected to the negative electrode tab of each of the battery cells.

[0017] According to one embodiment of this disclosure, the flexible battery includes a battery region and a peripheral region surrounding the battery region; the battery region includes a rigid region overlapping the battery cells and a bending region located between the battery cells;

[0018] In the outer perimeter area and the bending area, the first flexible encapsulation layer and the second flexible encapsulation layer are directly connected to seal the rigid area; the protruding portion of the second flexible encapsulation layer covers the side of the battery cell.

[0019] According to one embodiment of this disclosure, the first flexible encapsulation layer is a steel-plastic film.

[0020] According to one embodiment of this disclosure, the second flexible encapsulation layer is an aluminum-plastic film.

[0021] According to one embodiment of the present disclosure, along the direction away from the battery cell, the first flexible encapsulation layer includes a first heat-sealing layer, a first metal layer, and a first protective layer stacked sequentially.

[0022] Along the direction away from the battery cell, the second flexible encapsulation layer includes a second heat-sealing layer, a second metal layer, and a second protective layer stacked sequentially.

[0023] The elastic modulus of the first metal layer is greater than that of the second metal layer.

[0024] According to one embodiment of this disclosure, the material of the first protective layer is nylon, and / or the material of the second protective layer is nylon.

[0025] According to one embodiment of this disclosure, the material of the first metal layer is stainless steel.

[0026] According to one embodiment of this disclosure, the material of the second metal layer is aluminum foil.

[0027] According to one embodiment of this disclosure, the edge of the flexible battery is provided with crack detection traces; the crack detection traces extend at least partially along the first direction; wherein the crack detection traces are encapsulated within the first flexible encapsulation layer or the second flexible encapsulation layer.

[0028] According to one embodiment of this disclosure, along the direction away from the battery cell, the first flexible encapsulation layer includes a first heat-sealing layer, a first adhesive layer, a first metal layer, a second adhesive layer, and a first protective layer stacked sequentially.

[0029] The crack detection wiring is sandwiched between the second adhesive layer and the first protective layer.

[0030] According to another aspect of this disclosure, an electronic device is provided, including the flexible battery described above.

[0031] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0033] Figure 1 This is a cross-sectional structural diagram of a flexible battery according to one embodiment of the present disclosure.

[0034] Figure 2 This is a top view schematic diagram of a flexible packaging structure according to one embodiment of the present disclosure.

[0035] Figure 3 This is a top view schematic diagram of each battery cell in one embodiment of the present disclosure.

[0036] Figure 4 This is a cross-sectional view of the first flexible encapsulation layer in one embodiment of the present disclosure.

[0037] Figure 5 This is a cross-sectional view of the second flexible encapsulation layer in one embodiment of the present disclosure.

[0038] Figure 6 This is a schematic diagram showing the location of crack detection traces in one embodiment of the present disclosure.

[0039] Figure 7 This is a cross-sectional view of the first flexible encapsulation layer in one embodiment of the present disclosure.

[0040] Figure 8 This is a schematic diagram illustrating the structure of a circuit board and crack detection traces in one embodiment of this disclosure. For clarity, in... Figure 8 The crack detection pins and crack detection pads are staggered and do not overlap.

[0041] Figure 9 This is a schematic diagram of the equivalent circuit of the boost sub-circuit in one embodiment of the present disclosure.

[0042] Figure 10 This is a circuit diagram of the boost sub-circuit during the charging phase, as described in one embodiment of the present disclosure.

[0043] Figure 11 This is a circuit diagram of the boost sub-circuit during the discharge phase in one embodiment of the present disclosure.

[0044] Explanation of reference numerals in the attached figures:

[0045] 100. Battery cell; 101. Battery cell body; 102. Positive tab; 103. Negative tab; 200. Flexible conductive layer; 201. First flexible conductive strip; 202. Second flexible conductive strip; FES. Flexible encapsulation structure; F100. First flexible encapsulation layer; F200. Second flexible encapsulation layer; F301. Protruding portion; F302. Recessed portion; F101. First heat-sealing layer; F102. First adhesive layer; F103. First metal layer; F104. Second adhesive layer; F105. First protective layer; F20 1. Second heat-sealing layer; F202. Third adhesive layer; F203. Second metal layer; F204. Fourth adhesive layer; F205. Second protective layer; AA. Battery area; A1. Rigid area; A2. Bending area; BB. Peripheral area; B1. First peripheral area; B2. Second peripheral area; B3. Third peripheral area; B4. Fourth peripheral area; PCD. Crack detection trace; PCD1. First sub-detection trace; PCD2. Second sub-detection trace; PCD3. Third sub-detection trace; H1. First direction; H2. Second direction. Detailed Implementation

[0046] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0047] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the device of the icon is flipped upside down, the component described as "up" will become the component described as "down." When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0048] The terms “a,” “one,” “the,” and “at least one” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first” and “second” are used only as markers and are not a limitation on the number of objects.

[0049] This disclosure provides a flexible battery, see [link to relevant documentation] Figure 1 The flexible battery includes a plurality of cells 100 spaced apart along a first direction H1, and a flexible encapsulation structure FES covering each cell 100.

[0050] See Figure 1 and Figure 2 In the flexible encapsulation structure FES, the area corresponding to the cell 100 is the rigid area A1 (i.e., the area overlapping with the cell 100 is the rigid area A1), and the area between the cells 100 is the bending area A2; each bending area A2 and each rigid area A1 constitutes a battery area AA in which the cells 100 are distributed. The flexible encapsulation structure FES may also include a peripheral area BB surrounding the battery area AA to achieve more efficient encapsulation of each cell 100. In other words, in the flexible battery of this disclosure, the flexible encapsulation structure FES has a battery area AA and a peripheral area BB surrounding the battery area AA; the battery area AA includes a plurality of rigid areas A1 and a plurality of bending areas A2 alternately arranged along the first direction H1. See also Figure 2 Both ends of the battery region AA are rigid regions A1. Each cell 100 is correspondingly arranged with each rigid region A1; the cell 100 is located in the corresponding rigid region A1 and is encapsulated within the flexible encapsulation structure FES. Thus, in the flexible battery of this disclosure, the cell 100 is located in the rigid region A1 and encapsulated within the flexible encapsulation structure FES, and the flexible battery can be bent in the bending region A2. This allows the flexible battery of this disclosure to be bent between adjacent cells 100, enabling the flexible battery to achieve flexible shapes such as bending, folding, or twisting.

[0051] Optionally, see Figure 1The flexible encapsulation structure FES includes a first flexible encapsulation layer F100 and a second flexible encapsulation layer F200 stacked together; the battery cell 100 is disposed between the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200. In the rigid region A1, both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 are connected to and isolated by the battery cell 100. In the peripheral region BB and the bending region A2, the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 are directly connected to seal the rigid region A1. Furthermore, a heat-sealing layer is provided on the inner surface of both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200. Thus, in the rigid region A1, both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 are bonded to the battery cell 100 to achieve fixation of the battery cell 100. In the outer perimeter area BB and the bending area A2, the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 are bonded together to achieve encapsulation of the battery cell 100.

[0052] In some implementations, see Figure 1 The first flexible encapsulation layer F100 can be a flat encapsulation layer; the second flexible encapsulation layer F200 can be a raised / lowered encapsulation layer. Thus, the flexible battery has a flat side and a raised / lowered side arranged opposite to each other; the encapsulation layer on the flat side of the flexible encapsulation structure FES is the first flexible encapsulation layer F100, and the encapsulation layer on the raised / lowered side is the second flexible encapsulation layer F200. When the flexible battery is in a flat state, the first flexible encapsulation layer F100 (flat encapsulation layer) can be laid flat as a plane, with each cell 100 located on one side of this plane. In other words, in the flat state, the portion of the first flexible encapsulation layer F100 in the bending area A2 does not need to be bent into the gap between the cells 100. The second flexible encapsulation layer F200 (raised / lowered encapsulation layer) can include a protruding portion F301 covering the cell 100, and a recessed portion F302 located between adjacent cells 100. In other words, the morphology of the second flexible encapsulation layer F200 can undulate with the cell 100. In the rigid region A1, the second flexible encapsulation layer F200 covers the surface of the cell 100 (near or away from the surface of the first flexible encapsulation layer F100) and protrudes from the surface of the first flexible encapsulation layer F100; this portion is the protruding portion F301 of the second flexible encapsulation layer F200. In the bending region A2, the second flexible encapsulation layer F200 is between adjacent cells 100 and directly covers the surface of the first flexible encapsulation layer F100, thus serving as the recessed portion F302 of the second flexible encapsulation layer F200. Further, see... Figure 1 The protruding portion F301 of the second flexible encapsulation layer F200 also covers the side surface of the battery cell (the surface where the battery cells are close to or far apart from each other). In a further embodiment, the protruding portion F301 of the second flexible encapsulation layer F200 also covers the end face of the battery cell (the surface at both ends along the length of the battery cell).

[0053] Of course, in other embodiments of this disclosure, both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 may be bump encapsulation layers.

[0054] Optionally, see Figure 4 Along the direction away from the battery cell 100, the first flexible encapsulation layer F100 includes a first heat-sealing layer F101, a first metal layer F103, and a first protective layer F105 stacked sequentially. The first heat-sealing layer F101 is used to fix the first metal layer F103 and for heat-sealing encapsulation. The first metal layer F103 is used to isolate water and oxygen. The first protective layer F105 is used to provide protection for the first flexible encapsulation layer F100.

[0055] Furthermore, a first adhesive layer F102 is provided between the first heat-sealing layer F101 and the first metal layer F103; a second adhesive layer F104 is provided between the first metal layer F103 and the first protective layer F105. Thus, the first heat-sealing layer F101, the first metal layer F103, and the first protective layer F105 are connected by two adhesive layers. Even further, the materials of the first adhesive layer F102 and the second adhesive layer F104 can be different. Of course, in other embodiments of this disclosure, the materials of the first adhesive layer F102 and the second adhesive layer F104 can also be the same.

[0056] In one embodiment of this disclosure, the first heat-sealing layer F101 may be a polypropylene layer, particularly a cast polypropylene layer.

[0057] In one embodiment of this disclosure, the material of the first adhesive layer F102 may be modified polypropylene.

[0058] In one embodiment of this disclosure, the material of the second adhesive layer F104 may be polyester or polyurethane.

[0059] In one embodiment of this disclosure, the first protective layer F105 may be a nylon layer.

[0060] Optionally, the thickness of the first flexible encapsulation layer F100 can be in the range of 40 to 150 micrometers, for example in the range of 80 to 120 micrometers, or even in the range of 45 to 55 micrometers.

[0061] Optionally, see Figure 5 Along the direction away from the battery cell 100, the second flexible encapsulation layer F200 includes a second heat-sealing layer F201, a second metal layer F203, and a second protective layer F205 stacked sequentially. The second heat-sealing layer F201 is used to fix the second metal layer F203 and for heat-sealing encapsulation. The second metal layer F203 is used to isolate water and oxygen. The second protective layer F205 is used to provide protection for the second flexible encapsulation layer F200.

[0062] Furthermore, a third adhesive layer F202 is disposed between the second heat-sealing layer F201 and the second metal layer F203; a fourth adhesive layer F204 is disposed between the second metal layer F203 and the second protective layer F205. Thus, the second heat-sealing layer F201, the second metal layer F203, and the second protective layer F205 are connected by two adhesive layers. Furthermore, the materials of the third adhesive layer F202 and the fourth adhesive layer F204 can be different. Of course, in other embodiments of this disclosure, the materials of the third adhesive layer F202 and the fourth adhesive layer F204 can also be the same.

[0063] In one embodiment of this disclosure, the second heat-sealing layer F201 may be a polypropylene layer, particularly a cast polypropylene layer.

[0064] In one embodiment of this disclosure, the material of the third adhesive layer F202 may be modified polypropylene.

[0065] In one embodiment of this disclosure, the material of the fourth adhesive layer F204 may be polyester or polyurethane.

[0066] In one embodiment of this disclosure, the second protective layer F205 may be a nylon layer.

[0067] Optionally, the thickness of the second flexible encapsulation layer F200 can be in the range of 40 to 150 micrometers, for example in the range of 80 to 120 micrometers, or even in the range of 45 to 55 micrometers.

[0068] Optionally, see Figure 3 The battery cell 100 includes a battery cell body 101 and positive electrode tabs 102 and negative electrode tabs 103 located at both ends of the battery cell body 101. Multiple battery cell bodies 101 are arranged sequentially along the first direction H1, and there is a preset gap between two adjacent battery cells 100.

[0069] Optionally, see Figure 3 ( Figure 3 (The flexible packaging structure is not shown in the diagram). The flexible battery may further include a flexible conductive layer 200, which is electrically connected to each cell 100. The portion of the flexible conductive layer 200 electrically connected to each cell 100 may be encapsulated within the flexible packaging structure. At least a portion of the flexible conductive layer 200 may extend out of the flexible packaging structure for electrical connection to an external circuit (e.g., a circuit board). The flexible battery is electrically connected to the external circuit via the flexible conductive layer 200 for charging or discharging. In one embodiment of this disclosure, the flexible conductive layer 200 is at least partially sandwiched between a first flexible packaging layer F100 and a second flexible packaging layer F200.

[0070] Optionally, the portion of the flexible conductive layer 200 extending beyond the flexible packaging structure may have a bonding region at its end (the end furthest from the flexible packaging structure). Within the bonding region, the flexible conductive layer 200 may have bonding pads, which may include battery pads electrically connected to external circuitry. External circuitry, such as an external flexible circuit board, can be electrically connected to the flexible conductive layer 200 via the battery pads, thereby receiving electrical energy from the flexible battery or charging the flexible battery.

[0071] In one embodiment of this disclosure, see Figure 3 The flexible conductive layer 200 includes a first flexible conductive strip 201 and a second flexible conductive strip 202. The first flexible conductive strip 201 is electrically connected to the positive electrode tab 102 of each battery cell 100, so that the positive electrodes of each battery cell 100 are connected in parallel. The second flexible conductive strip 202 is electrically connected to the negative electrode tab 103 of each battery cell 100, so that the negative electrodes of each battery cell 100 are connected in parallel.

[0072] Optionally, the battery cell can be a lithium battery structure. In one embodiment of this disclosure, the battery cell has a first separator, a negative electrode, a second separator, a positive electrode, a negative electrode tab disposed on the negative electrode, and a positive electrode tab disposed on the positive electrode in sequence. To increase the capacity of the battery cell, the electrodes (positive electrode and negative electrode) and separators (first separator and second separator) of the battery cell can be wound to form a rigid energy storage unit.

[0073] Optionally, see Figure 3 The positive tab 102 and the negative tab 103 can be bent to the surface of the cell 100 (near or away from the surface of the first flexible encapsulation layer F100) to be electrically connected to the flexible conductive layer 200. In one embodiment of this disclosure, the flexible conductive layer 200 is disposed between the first flexible encapsulation layer F100 and the cell 100, and extends beyond the flexible encapsulation structure along the first direction H1.

[0074] Optionally, in some embodiments, the spacing between two adjacent cells (the dimension of the distance between two adjacent cells in a first direction) is not less than the thickness of the cell (the dimension between the upper and lower surfaces of the cell). This allows the flexible battery to maintain greater flexibility. Of course, in other embodiments of this disclosure, the spacing between two adjacent cells may also be less than the thickness of the cell.

[0075] In related technologies, when flexible batteries are bent, stress concentration is prone to occur in the outer region BB. Specifically, stress concentration easily occurs at the intersection of the extension line of the bending region A2 and the outer region BB, which can lead to microcracks in the flexible encapsulation structure FES at that location. These microcracks may cause failure problems such as leakage and swelling of the flexible battery, and may also pose safety hazards.

[0076] In related technologies, microcracks are often difficult to detect due to their extremely small size, especially since they cannot be quickly observed with the naked eye. This can lead to certain safety hazards in flexible batteries.

[0077] In some embodiments of this disclosure, see Figure 6 To efficiently detect microcracks at the edge of the flexible battery encapsulation structure (FES), the flexible battery can be equipped with a crack detection trace (PCD). The PCD can be located in the peripheral region BB and at least partially extend along the first direction H1; wherein the PCD is encapsulated within the flexible battery encapsulation structure (FES). In this embodiment, when a microcrack occurs at the location of the PCD, the microcrack will damage the PCD, for example, causing an increase in resistance at the microcrack location (due to local breakage or thinning, leading to increased resistance) or breakage. Therefore, the presence of a microcrack can be determined by detecting the electrical state of the PCD (e.g., resistance magnitude or whether it is open-circuited).

[0078] In these embodiments, the crack detection trace PCD is encapsulated and protected by the flexible package structure FES. This ensures that the electrical state of the crack detection trace PCD is consistent with the state of the flexible package structure FES in the peripheral region BB, improving the accuracy of crack detection. In this embodiment, the crack detection trace PCD is avoided from being located outside the flexible package structure FES. If the crack detection trace PCD is located outside the flexible package structure FES, when non-microcrack factors cause the crack detection trace PCD to break, such as when the crack detection trace PCD is corroded or scratched, the change in the electrical state of the crack detection trace PCD is not consistent with the state of the flexible package structure FES; this is detrimental to the accurate detection of microcracks in the flexible package structure FES.

[0079] Optionally, see Figure 7 The crack detection trace PCD can be located within the first flexible encapsulation layer F100. In this way, the first flexible encapsulation layer F100 can protect the crack detection trace PCD, preventing it from being exposed and scratched or corroded.

[0080] In one embodiment of this disclosure, the crack detection trace PCD can be located between the second adhesive layer F104 and the first protective layer F105. Thus, the crack detection trace PCD can be protected by the first protective layer F105 and insulated from the first metal layer F103 by the second adhesive layer F104. Furthermore, a film layer such as the first metal layer F103 is provided between the crack detection trace PCD and the first heat-sealing layer F101, preventing the impact of melting and deformation of the first heat-sealing layer F101 during heat sealing on the crack detection trace PCD.

[0081] In some implementations, see Figure 8 The ends of the crack detection trace PCD can be electrically connected to crack detection pads (Pad1, Pad2). These pads are used to connect to external circuits (e.g., circuit board 300) so that the external circuits can detect whether the crack detection trace PCD is open-circuited or damaged. In one embodiment of this disclosure, the crack detection pads (Pad1, Pad2) can be directly connected to the ends of the crack detection trace PCD. Of course, in other embodiments of this disclosure, the crack detection pads may not be directly connected to the crack detection trace, but can be connected indirectly through other conductive traces; that is, the crack detection pads and the crack detection trace can be indirectly connected through other conductive traces.

[0082] In some embodiments, the crack detection traces (PCD) can converge towards the flexible conductive layer 200 and extend towards the bonding region; the crack detection pads can be disposed in the bonding region. This allows the flexible battery to converge with various externally connected pads, improving integration and facilitating connection to external circuits. Of course, in other embodiments of this disclosure, the crack detection pads can be disposed in the bonding region, and the crack detection traces may not converge into the bonding region, but rather be electrically connected to the crack detection pads through other conductive traces connected to the bonding region.

[0083] See Figure 2 The outer perimeter region BB may include a first outer perimeter region B1, a third outer perimeter region B3, a second outer perimeter region B2, and a fourth outer perimeter region B4 connected end-to-end. The first outer perimeter region B1 and the second outer perimeter region B2 are located on both sides of the battery region AA and both extend along a first direction H1. The third outer perimeter region B3 and the fourth outer perimeter region B4 are located on both sides of the battery region AA and both extend along a second direction H2. The second direction H2 is the extension direction of the cell 100. Furthermore, the first direction H1 and the second direction H2 are perpendicular.

[0084] In one embodiment of this disclosure, see Figure 6 The crack detection trace PCD includes a first sub-detection trace PCD1 and a second sub-detection trace PCD2 that are electrically connected to each other. The first sub-detection trace PCD1 passes through the first peripheral region B1 along the first direction H1, and the second sub-detection trace PCD2 passes through the second peripheral region B2 along the first direction H1. When the flexible battery is bent, stress concentration easily occurs in the first peripheral region B1 and the second peripheral region B2, resulting in microcracks. In this embodiment, the crack detection trace PCD passes through the first peripheral region B1 and the second peripheral region B2 along the first direction H1, thus effectively detecting microcracks in the first peripheral region B1 and the second peripheral region B2.

[0085] Furthermore, the crack detection trace PCD also includes a third sub-detection trace PCD3 that runs through the third peripheral region B3, and the third sub-detection trace PCD3 connects to the first sub-detection trace PCD1 and the second sub-detection trace PCD2. In this way, the crack detection trace PCD can also detect microcracks located in the third peripheral region B3.

[0086] Of course, it is understood that in some implementations, the crack detection trace PCD may also include a fourth detection sub-trace located in the fourth peripheral region B4 in order to detect microcracks located in the fourth peripheral region B4.

[0087] Optionally, the number of crack detection traces (PCDs) can be one or more.

[0088] Optionally, the thickness of the crack detection trace PCD is in the range of 0.3 to 1.5 micrometers. The required crack detection trace PCD can be formed by methods such as printing, vapor deposition, and magnetron sputtering.

[0089] Optionally, the material of the crack detection trace PCD can be a metallic material, which may include a single metal layer or multiple stacked metal layers. For example, in one embodiment of this disclosure, the crack detection trace PCD includes a titanium layer, an aluminum layer, and a titanium layer stacked sequentially. Of course, in other embodiments of this disclosure, the crack detection trace PCD may also use other conductive materials, such as organic conductive materials or conductive metal oxides.

[0090] Optionally, the width of the crack detection trace PCD is in the range of 0.2 to 1.0 mm; further, the width of the crack detection trace PCD is in the range of 0.4 to 0.7 mm. For example, the width of the crack detection trace PCD is 0.5 mm.

[0091] Optionally, the distance between the crack detection trace PCD and the edge of the flexible packaging structure FES is in the range of 0.5 to 1.5 mm. This ensures that the crack detection trace PCD is positioned close to the edge of the flexible packaging structure FES, thus promptly reflecting microcracks at the edge of the FES. Further, the distance between the crack detection trace PCD and the edge of the flexible packaging structure FES is in the range of 0.8 to 1.0 mm. For example, in one embodiment of this disclosure, the distance between the crack detection trace PCD and the edge of the flexible packaging structure FES is 0.93 mm.

[0092] This disclosure may also provide an external circuit for bonding with a flexible battery, such as a circuit board. See also Figure 8The circuit board 300 includes a resistance detection circuit 310. The resistance detection circuit 310 is electrically connected to the crack detection trace PCD of the flexible battery and is configured to detect the resistance of the crack detection trace PCD. Thus, the presence of microcracks at the edge of the flexible battery can be determined based on the resistance of the crack detection trace PCD.

[0093] Furthermore, the circuit board 300 may also include a bootstrap circuit 320. The bootstrap circuit 320 is electrically connected to the crack detection trace PCD and is configured to receive a first voltage and output a second voltage to the crack detection trace; the second voltage is higher than the first voltage. Thus, the bootstrap circuit 320 can output a higher voltage signal to the crack detection trace to accelerate the resistance change of the crack detection trace PCD at the microcrack, thereby improving the sensitivity of microcrack detection. Specifically, when a microcrack appears at the edge of the flexible battery, the crack detection trace PCD at that location becomes fragile and its resistance increases; when a high-voltage signal passes through, the heat generated by the crack detection trace PCD at that location will be higher than at other locations, thus causing the crack detection trace PCD to break more quickly at that location.

[0094] Furthermore, the bootstrap circuit 320 can generate a high-voltage pulse signal with a peak voltage of the second voltage, thereby generating a detection current on the crack detection trace PCD or burning the crack detection trace PCD at the crack.

[0095] See Figure 8 The circuit board 300 may also include crack detection pins (Pin1, Pin2) for bonding with crack detection pads (Pad1, PAD2). Thus, the circuit board 300 can be electrically connected to the crack detection trace PCD, thereby detecting the resistance of the crack detection trace PCD and determining whether microcracks have formed at the edge of the flexible battery based on the resistance of the crack detection trace PCD.

[0096] In one embodiment of this disclosure, the bootstrap circuit 320 includes a boost sub-circuit 321 and a logic control sub-circuit 322. See also... Figure 9 The boost circuit 321 includes:

[0097] The first capacitor C1 is connected to the first node N1 and the second node N2 respectively.

[0098] The first switch S1 has one end electrically connected to the first node N1, and the other end is used to apply the reference voltage GND.

[0099] The second switch S2 has one end electrically connected to the second node N2 and the other end connected to the input terminal Vin for applying the first voltage;

[0100] The third switch S3 has one end used to apply the first voltage and the other end electrically connected to the first node N1;

[0101] The fourth switch S4 is connected at one end to the second node N2 and at the other end to the output terminal Vout for outputting the second voltage;

[0102] The second capacitor C2 has one end used to apply the reference voltage GND, and the other end connected to the output terminal Vout.

[0103] The logic control sub-circuit 322 is used to control the on / off state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4. Specifically, the logic control sub-circuit is configured to turn on the first switch S1 and the second switch S2 and turn off the third switch S3 and the fourth switch S4 during the charging phase. The logic control sub-circuit 322 is also configured to turn off the first switch S1 and the second switch S2 and turn on the third switch S3 and the fourth switch S4 during the discharging phase.

[0104] In this embodiment, the bootstrap circuit 320 operates as follows:

[0105] During the charging phase, see Figure 10 The input terminal Vin is loaded with a first voltage V1. The first switch S1 and the second switch S2 are open, while the third switch S3 and the fourth switch S4 are closed. At this time, across the first capacitor C1, the voltage at the first node N1 is 0V, and the voltage at the second node N2 is the first voltage V1. The potential difference between the second node N2 and the first node N1 is equal to the first voltage V1.

[0106] During the discharge phase, see Figure 11 A first voltage V1 is applied to the input terminal Vin. The first switch S1 and the second switch S2 are closed, while the third switch S3 and the fourth switch S4 are open. At this time, the voltage at the first node N1 is equal to the first voltage V1. Under the coupling effect of the first capacitor C1, the voltage at the second node N2 is bootstrapped to 2V1. This voltage at the second node N2 is output as the output voltage through the output terminal Vout. The voltage output at the output terminal Vout is the second voltage, with a magnitude of 2V1.

[0107] In some embodiments of this disclosure, the risk of microcrack formation can be reduced by adjusting the flexible encapsulation structure (FES). See also Figure 1The first flexible encapsulation layer F100 can be a flat encapsulation layer. The second flexible encapsulation layer F200 can be a raised / lowered encapsulation layer, which may include a protruding portion F301 covering the cell 100 and a recessed portion F302 located between adjacent cells 100. Thus, the flexible battery can be bent towards the raised / lowered side. The elastic modulus of the first flexible encapsulation layer F100 can be greater than that of the second flexible encapsulation layer F200. Therefore, by making the elastic modulus of the flat encapsulation layer larger, the neutral plane of the flexible encapsulation structure FES during bending can be adjusted, making the neutral plane closer to the outer surface of the first flexible encapsulation layer F100, which has a large elastic modulus. Thus, during bending, most of the flexible encapsulation structure FES is located on the side of the neutral layer closer to the cell 100 and bears compressive stress, while a small portion of the flexible encapsulation structure FES is located on the side of the neutral layer away from the cell 100 and bears tensile stress. For the portion of the flexible encapsulation structure FES bearing tensile stress, due to the offset of the neutral plane, this portion has a small thickness, and therefore its tensile deformation is small. Overall, the flexible encapsulation structure (FES) exhibits greater resistance to bending and is less prone to microcracks caused by bending. This improves the bending resistance of flexible batteries.

[0108] This disclosure presents a bending reliability test (50,000 bends) on three different flexible batteries.

[0109] In the first type of flexible battery, both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 employ a high elastic modulus. The results show that the flexible encapsulation structure FES in the first type of flexible battery develops creases at the bending location. This indicates that the first type of flexible battery suffers damage at the edge and fails the bending reliability test.

[0110] In the second type of flexible battery, both the first flexible encapsulation layer F100 and the second flexible encapsulation layer F200 employ a low elastic modulus. The results show that the flexible encapsulation structure FES in the second type of flexible battery develops creases at the bending location. This indicates that the second type of flexible battery suffers damage at the edge and fails the bending reliability test.

[0111] In the third type of flexible battery, the first flexible encapsulation layer F100 employs a high elastic modulus flexible encapsulation layer, while the second flexible encapsulation layer F200 employs a low elastic modulus flexible encapsulation layer. Results show that no creases are formed at the edges of the third type of flexible battery. This indicates that the flexible battery of this disclosure embodiment has passed the bending reliability test, and its risk of microcrack formation is very low.

[0112] Optionally, the elastic modulus of the first metal layer can be greater than that of the second metal layer, thereby making the elastic modulus of the first flexible encapsulation layer F100 greater than that of the second flexible encapsulation layer F200.

[0113] Optionally, the elastic modulus of the first flexible encapsulation layer F100 is 6 to 11 times that of the second flexible encapsulation layer F200. This effectively adjusts the neutral plane of the flexible encapsulation structure FES, thereby improving the bending reliability of the flexible battery.

[0114] In one embodiment of this disclosure, the elastic modulus of the first flexible encapsulation layer F100 is in the range of 180 GPa to 220 GPa. Further, the first flexible encapsulation layer F100 is a steel-plastic film. Exemplarily, the first metal layer F103 can be a stainless steel layer, for example, 304 stainless steel. It is understood that the first flexible encapsulation layer F100 can also be other flexible encapsulation layers with a high elastic modulus.

[0115] In one embodiment of this disclosure, the Poisson's ratio of the first flexible encapsulation layer F100 can be between 0.35 and 0.45, for example, between 0.39 and 0.41.

[0116] In one embodiment of this disclosure, the thickness of the first flexible encapsulation layer F100 can be between 40 and 60 micrometers, for example, between 45 and 55 micrometers.

[0117] In one embodiment of this disclosure, the elastic modulus of the second flexible encapsulation layer F200 is in the range of 20 GPa to 30 GPa. Further, the second flexible encapsulation layer F200 is an aluminum-plastic film. Exemplarily, the second metal layer F203 can be an aluminum foil layer. It is understood that the second flexible encapsulation layer F200 can also be other flexible encapsulation layers with low elastic modulus.

[0118] In one embodiment of this disclosure, the Poisson's ratio of the second flexible encapsulation layer F200 can be between 0.35 and 0.45, for example, between 0.39 and 0.41.

[0119] In one embodiment of this disclosure, the thickness of the second flexible encapsulation layer F200 can be between 40 and 60 micrometers, for example, between 45 and 55 micrometers.

[0120] This disclosure also provides an electronic device comprising any of the flexible batteries described in the above-described flexible battery embodiments. The electronic device can be a smartwatch, smartphone, or other type of electronic device; in particular, it can be a flexible portable electronic device, such as a flexible wearable device. Since this electronic device possesses any of the flexible batteries described in the above-described flexible battery embodiments, it has the same beneficial effects, which will not be repeated here.

[0121] In one embodiment of this disclosure, the electronic device further includes a display panel, and a flexible battery is used to power the display panel.

[0122] In a further embodiment, the display panel is a flexible display panel. Thus, the electronic device employs a flexible battery and a flexible display panel, making the entire electronic device bendable.

[0123] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A flexible battery, comprising: First flexible encapsulation layer; Multiple battery cells are disposed on one side of the first flexible encapsulation layer and spaced apart along the first direction; The second flexible encapsulation layer includes a protruding portion covering the battery cell and a recessed portion located between adjacent battery cells; The elastic modulus of the first flexible encapsulation layer is greater than that of the second flexible encapsulation layer.

2. The flexible battery according to claim 1, wherein, The elastic modulus of the first flexible encapsulation layer is 6 to 11 times that of the second flexible encapsulation layer.

3. The flexible battery according to claim 1, wherein, The elastic modulus of the first flexible encapsulation layer is in the range of 180 GPa to 220 GPa.

4. The flexible battery according to claim 1, wherein, The elastic modulus of the second flexible encapsulation layer is in the range of 20 GPa to 30 GPa.

5. The flexible battery according to claim 1, wherein, The spacing between two adjacent battery cells is not less than the thickness of the battery cell.

6. The flexible battery according to claim 1, wherein, The battery cell includes a battery cell body and positive and negative tabs located at both ends of the battery cell body; the positive and negative tabs are bent to the surface of the battery cell body; The flexible battery further includes a flexible conductive layer extending along the first direction; the flexible conductive layer is at least partially sandwiched between the first flexible encapsulation layer and the second flexible encapsulation layer, and is electrically connected to the positive electrode tab and the negative electrode tab.

7. The flexible battery according to claim 6, wherein, The flexible conductive layer includes a first flexible conductive strip and a second flexible conductive strip extending along a first direction; the first flexible conductive strip is electrically connected to the positive electrode tab of each of the battery cells; and the second flexible conductive strip is electrically connected to the negative electrode tab of each of the battery cells.

8. The flexible battery according to claim 1, wherein, The flexible battery includes a battery region and a peripheral region surrounding the battery region; the battery region includes a rigid region overlapping the battery cells and a bending region located between the battery cells; In the outer perimeter area and the bending area, the first flexible encapsulation layer and the second flexible encapsulation layer are directly connected to seal the rigid area; the protruding portion of the second flexible encapsulation layer covers the side of the battery cell.

9. The flexible battery according to any one of claims 1 to 8, wherein, The first flexible encapsulation layer is a steel-plastic film.

10. The flexible battery according to any one of claims 1 to 8, wherein, The second flexible encapsulation layer is an aluminum-plastic film.

11. The flexible battery according to any one of claims 1 to 8, wherein, Along the direction away from the battery cell, the first flexible encapsulation layer includes a first heat-sealing layer, a first metal layer, and a first protective layer stacked sequentially. Along the direction away from the battery cell, the second flexible encapsulation layer includes a second heat-sealing layer, a second metal layer, and a second protective layer stacked sequentially. The elastic modulus of the first metal layer is greater than that of the second metal layer.

12. The flexible battery according to claim 11, wherein, The material of the first protective layer is nylon, and / or the material of the second protective layer is nylon.

13. The flexible battery according to claim 11, wherein, The material of the first metal layer is stainless steel.

14. The flexible battery according to claim 11, wherein, The material of the second metal layer is aluminum foil.

15. The flexible battery according to any one of claims 1 to 8, wherein, The edge of the flexible battery is provided with crack detection traces; the crack detection traces extend at least partially along the first direction; wherein the crack detection traces are encapsulated within the first flexible encapsulation layer or the second flexible encapsulation layer.

16. The flexible battery according to claim 15, wherein, Along the direction away from the battery cell, the first flexible encapsulation layer includes a first heat-sealing layer, a first adhesive layer, a first metal layer, a second adhesive layer, and a first protective layer stacked sequentially. The crack detection wiring is sandwiched between the second adhesive layer and the first protective layer.

17. An electronic device comprising the flexible battery according to any one of claims 1 to 16.

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