Ultra-thin battery without wrinkles during bending and twisting and manufacturing method of ultra-thin battery

Abstract

The invention discloses an ultrathin battery without wrinkles during bending and twisting and a manufacturing method thereof, and relates to the field of batteries and manufacturing methods thereof. In the invention, the battery structure is configured to be a bendable ultrathin battery, the top and the bottom of the battery cell body are fixed in the outer packaging body through the first connecting adhesive layers, and the second connecting adhesive layers arranged on the two sides of the diaphragm are adopted in the battery to connect the positive pole piece and the negative pole piece, so that all components (the outer packaging body, the battery cell body and the internal pole piece group) synchronously deform when the battery is bent and twisted; and through hot-pressing baking of the manufacturing method, bonding of the first connecting adhesive layer and the second connecting adhesive layer is strengthened, and vacuum suction is performed after formation, so that the internal space of the outer packaging body is reduced, pole piece dislocation, wrinkling or cracking is effectively avoided, the overall bending and twisting performance and safety of the battery are improved, and the long-life requirement of bending scenes such as intelligent cards and medical devices is met.

Description

Technical Field

[0001] The present invention relates to the field of batteries and manufacturing methods thereof, and in particular to an ultra-thin battery that is not wrinkled when bent or twisted and a manufacturing method thereof. Background Art

[0002] Currently, lithium-ion batteries, as energy storage components, are widely used in various electronic products. With the differentiated development of different application scenarios, different types of electronic products have emerged. Different application scenarios also have different requirements for the lithium-ion batteries used in electronic products.

[0003] For example, smart cards such as electronic access cards and smart business cards. If these smart cards are equipped with ultra-thin batteries, they can add active functions such as sensing, communication, and authentication. These smart cards are only a few millimeters thick, and the ultra-thin batteries they are equipped with need to be even thinner, making them difficult to withstand the deformation caused by daily operations such as plugging, unplugging, and folding. Another example is medical devices such as electronic bandages and flexible biosensors, which often require ultra-thin batteries to operate. When applied to a patient's joints, they will deform with daily movement.

[0004] Ultra-thin batteries used in smart cards and medical devices typically consist of a casing, tabs, positive and negative electrodes, and a separator. These are stacked together to form a laminate structure and encapsulated in an outer package filled with electrolyte. When these batteries are bent or twisted by external forces, the positive and negative electrodes within the battery can become misaligned and deformed, ultimately leading to structural wrinkling, cracking, lithium deposition, and short circuits, significantly impacting the battery's lifespan and safety.

[0005] It can be seen from this that the current ultra-thin batteries have limited flexibility and cannot be adapted to battery products that will be bent and twisted during use. In bending and twisting application scenarios, there are problems such as shortened lifespan and safety risks. Summary of the Invention

[0006] In order to solve the problem that current lithium-ion batteries in the existing technology cannot support bending and twisting, the main purpose of the present invention is to provide an ultra-thin battery that does not wrinkle when bent and twisted, and a manufacturing method thereof, by fixing the positive and negative electrodes and the diaphragm in the battery cell as one, and fixing the battery cell as a whole to the outer packaging, so that the battery will not be damaged during the bending process, ensuring that the battery still has a long life under bending and twisting conditions.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides an ultra-thin battery that is bendable and wrinkle-free, comprising an outer packaging body, a laminated cell body disposed within the outer packaging body, and a tab connected to the cell body and extending outside the outer packaging body, wherein: The battery cell body includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet; The top and bottom of the battery cell body are respectively provided with a first connecting adhesive layer, and the top and bottom of the battery cell body are connected to the inner side of the outer packaging body through the first connecting adhesive layer; The upper and lower sides of the diaphragm are respectively provided with a second connecting adhesive layer, and the upper and lower sides of the diaphragm are respectively connected to the positive electrode sheet and the negative electrode sheet through the second connecting adhesive layer.

[0008] In the present invention, unless otherwise specified, when describing the structure of a component, the upper side (or top) refers to one of the sides of the battery with the largest area, and the lower side (or bottom) refers to the other side opposite thereto.

[0009] By adopting the above technical solution, the battery structure is configured as an ultra-thin battery. Specifically, it can be achieved by reducing the number of layers of the battery cell body, reducing the thickness of the positive electrode sheet, negative electrode sheet and / or diaphragm, reducing the thickness of the outer packaging body, and other one or more combinations of methods. When the two sides of the ultra-thin battery are bent and twisted downward, the upper side of the ultra-thin battery is stretched and the lower side of the ultra-thin battery is compressed. At this time, the upper side of the outer packaging body is stretched, pulling the top first connecting adhesive layer to stretch, and after being buffered by the first connecting adhesive layer, pulling the top of the battery cell body to stretch. Similarly, the lower side of the outer packaging body is compressed, pulling the bottom first connecting adhesive layer to compress, and after being buffered by the first connecting adhesive layer, pulling the bottom of the battery cell body to compress. In the battery cell body, since the positive electrode sheet and the negative electrode sheet are separated by the diaphragm, the upper and lower sides of the diaphragm are respectively connected to the positive electrode sheet and the negative electrode sheet through the second connecting adhesive layer, so that the battery cell body forms a structure in which each positive electrode sheet and negative electrode sheet are linked. When the battery cell body is bent, the upper positive and negative plates are stretched synchronously, and the lower positive and negative plates are compressed synchronously, so that when the battery is bent, there will be no misalignment or wrinkles between the plates, avoiding the occurrence of lithium plating and short circuit. The bending force is transmitted between the plates, avoiding the rupture of individual plates and damage to the battery.

[0010] As an improvement to the above-mentioned ultra-thin battery, at least two positive and negative electrodes are each provided, with the number of negative electrodes exceeding the number of positive electrodes by one layer. By adopting this technical solution, each positive electrode is sandwiched between two negative electrodes, preventing the positive electrode edge from directly contacting the electrolyte, suppressing lithium precipitation, and avoiding the resulting short circuit or thermal runaway risks, thereby enhancing the safety of the ultra-thin battery. Furthermore, the extra negative electrode can release the capacity potential of the positive electrode, effectively increasing the energy density of the ultra-thin battery.

[0011] As an improvement scheme for the above-mentioned ultra-thin battery, further, the uppermost negative electrode sheet and the lowermost negative electrode sheet are composed of a negative electrode current collector coated with a negative electrode coating on one side, a negative electrode coating is provided on the lower side of the uppermost negative electrode sheet, the upper side of the uppermost negative electrode sheet is connected to the first connecting adhesive layer, the upper side of the lowermost negative electrode sheet is provided with a negative electrode coating, the lower side of the lowermost negative electrode sheet is connected to the first connecting adhesive layer, and the remaining negative electrode sheets are composed of a negative electrode current collector coated with a negative electrode coating on both sides; the positive electrode sheet is composed of a positive electrode current collector coated with a positive electrode coating on both sides.

[0012] By adopting this technical solution, both the top and bottom negative electrode sheets are coated on a single side, effectively reducing the thickness of the battery cell. The top and bottom negative electrode sheets are securely connected to the first connecting adhesive layer via the negative current collector, forming a buffer interface that absorbs mechanical stress during bending or vibration, reducing the risk of delamination between the electrode sheet and the outer packaging. The double-sided coated positive electrode sheet and the intermediate double-sided negative electrode sheet form a symmetrical conductive network, alleviating edge current concentration, while the outer single-sided negative electrode sheet suppresses local polarization at the interface between the coating and the current collector.

[0013] As an improvement to the above-mentioned ultra-thin battery, further, the positive electrode current collector of each positive electrode sheet is provided with a positive electrode handle, each of which is welded together and connected to one electrode tab, and the negative electrode current collector of each negative electrode sheet is provided with a negative electrode handle, each of which is welded together and connected to the other electrode tab. By adopting the above technical solution, by providing the positive electrode handle on the positive electrode current collector, the multiple layers of positive electrode sheets are electrically connected to each other, and the positive electrode of the battery cell body is led out through one electrode tab; by providing the negative electrode handle on the negative electrode current collector, the multiple layers of negative electrode sheets are electrically connected to each other, and the negative electrode of the battery cell body is led out through the other electrode tab.

[0014] As an improvement to the above-mentioned ultra-thin battery, the two diaphragms are further connected at their edges to form a diaphragm bag, the positive electrode sheet is wrapped in the diaphragm bag, and the outer and inner sides of the diaphragm bag are respectively provided with a second connecting adhesive layer. By adopting this technical solution, the size of the positive electrode sheet is slightly smaller than that of the negative electrode sheet. By wrapping the positive electrode sheet in the diaphragm bag, not only does it facilitate the lamination process, but it also makes the overall size of the battery cell more compact and ensures the safety of the ultra-thin battery.

[0015] As an improvement to the aforementioned ultra-thin battery, the first connecting adhesive layer comprises a sheet structure made of pressure-sensitive rubber. At room temperature, the pressure-sensitive rubber is adhesive only on one side. After heat treatment, both sides become adhesive, and the thickness of the pressure-sensitive rubber decreases dramatically as the heating temperature increases. The pressure-sensitive rubber can be based on butyl rubber, chloroprene rubber, or modified silicone rubber.

[0016] By adopting the above technical solution, the first connecting adhesive layer can be easily adhered to the top and bottom of the battery cell body. At the same time, the single-sided adhesiveness allows the battery cell body with the first connecting adhesive layer to be packaged in the outer packaging body without gaps. After a simple heat treatment, the battery cell body can be firmly fixed to the outer packaging body.

[0017] As an improvement to the above-mentioned ultra-thin battery, the second connecting adhesive layer is formed by coating polyvinylidene fluoride or polymethyl methacrylate on the surface of the diaphragm.

[0018] By adopting this technical solution, the polyvinylidene fluoride or polymethyl methacrylate coating has excellent adhesion, which can strengthen the bond between the diaphragm and the electrode, reduce the risk of delamination during bending or vibration, and suppress internal short circuits caused by electrode misalignment. The diaphragm coating of polyvinylidene fluoride or polymethyl methacrylate balances the diaphragm's air permeability with lithium ion migration efficiency, reduces interfacial impedance, and inhibits lithium dendrite growth, extending cycle life.

[0019] As an improvement to the above-mentioned ultra-thin battery, the thickness of the battery cell body is less than or equal to 1.2 mm. By adopting the above-mentioned technical solution, the ultra-thin battery is easy to bend and twist, making it suitable for application scenarios such as smart cards and medical devices that require bending and twisting.

[0020] In a second aspect, the present invention provides a method for manufacturing the above-mentioned ultra-thin battery that does not wrinkle when bent, wherein the manufacturing method comprises the steps of: Producing a positive electrode sheet, a negative electrode sheet, a separator and a first connecting adhesive layer; wherein the surface of the separator is coated with a second connecting adhesive layer; The positive electrode sheet, the negative electrode sheet and the separator are stacked to form a battery cell body, and the battery cell body is subjected to a hot pressing process so that the second connecting adhesive layer of the separator is connected to the positive electrode sheet and the negative electrode sheet respectively; Weld the tabs to the battery body; A first connecting adhesive layer is provided on the top and bottom of the battery cell body, and then the battery cell body is packaged in an outer packaging body, and the first connecting adhesive layer is respectively connected to the battery cell body and the outer packaging body through baking; The battery is manufactured through liquid injection, formation and molding; wherein, after formation, the battery is vacuum-pumped to discharge excess electrolyte and gas generated by formation.

[0021] By adopting the above technical solution, the diaphragm is tightly connected to the upper and lower positive and negative electrodes through the second connecting adhesive layer and undergoes hot pressing and baking treatments, so that the battery cell body is tightly connected to the outer packaging through the first connecting adhesive layer. After formation, the battery is vacuum-sucked to reduce the internal space of the outer packaging, thereby further improving the overall bending and torsional performance and safety of the battery.

[0022] As an improvement to the above manufacturing method, in the baking step, the temperature is set at 85-95°C and the vacuum baking is performed for 10-14 hours; In the injection step, the electrolyte is injected at a rate of 3 to 4.5 g / Ah; In the formation step, the battery is charged at a constant current, left to stand to form the SEI film, and then pressurized at a temperature of 45°C and a pressure of 0.5 MPa. In the forming step, excess material of the outer packaging body is cut off and the outer packaging body is folded.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, the battery structure is configured as an ultra-thin battery that can be bent and twisted, wherein the top and bottom of the battery cell body are connected to the outer packaging body through a first connecting adhesive layer, and the diaphragm in the battery cell body is connected to the positive electrode sheet and the negative electrode sheet through a second connecting adhesive layer on the upper and lower sides, respectively. When the ultra-thin battery is bent and twisted, the outer packaging body and the battery cell body are bent and twisted as a whole, and the positive electrode sheet, diaphragm and negative electrode sheet in the battery cell body are bent and twisted as a whole, thereby avoiding the misalignment and wrinkling of the electrode sheets caused by bending and twisting, and avoiding the rupture of individual electrode sheets due to large bending and twisting forces. The ultra-thin battery can be used in application scenarios such as smart cards and medical devices that require bending and twisting, avoiding the occurrence of lithium plating, short circuit and rupture in application scenarios that require bending and twisting, and achieving the use requirement of the battery having a long life under bending and twisting conditions.

[0024] (2) The manufacturing method of the ultra-thin battery in the present invention is to process the second connecting adhesive layer on the upper and lower sides of the diaphragm so that the positive electrode sheet and the negative electrode sheet are connected to the upper and lower sides of the diaphragm respectively, and set the first connecting adhesive layer on the top and bottom of the battery body so that the battery body is connected to the outer packaging body, so that the battery is free from electrode dislocation, wrinkling and rupture when bending and twisting; then through hot pressing and baking treatment, the connection between the electrode sheets in the battery body is tighter, and the connection between the battery body and the outer packaging body is tighter; after formation, the battery is vacuum-sucked so that there is less space in the outer packaging body, which is beneficial to the overall bending and twisting of the battery.

[0025] The present invention will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic cross-sectional structure diagram of a battery cell body of an ultra-thin battery that is not wrinkled when bent according to a first embodiment of the present invention in a stacked state; Figure 2 A schematic cross-sectional view of a normal state of an ultra-thin battery that is not wrinkled when bent according to a first embodiment of the present invention; Figure 3A schematic cross-sectional structure diagram of an ultra-thin battery that does not wrinkle when bent and twisted according to a first embodiment of the present invention in a bent and twisted state and in a stacked state.

[0027] Figure 4 A schematic diagram of a stacked cross-sectional structure of a cell body of an ultra-thin battery that is not wrinkled when bent according to a second embodiment of the present invention; Figure 5 A schematic cross-sectional view of an ultra-thin battery that is bendable and wrinkle-free according to a second embodiment of the present invention.

[0028] Figure 6 A schematic diagram of the three-dimensional structure of a cell body of an ultra-thin battery that does not wrinkle when bent or twisted in a stacked state according to an embodiment of the present invention; Figure 7 A schematic diagram of the three-dimensional structure of an ultra-thin battery that does not wrinkle when bent or twisted according to an embodiment of the present invention; Figure 8 Schematic diagram of capacity retention and cycle number curves of an ultra-thin battery that does not wrinkle when bent and twisted before and after bending and twisting testing according to an embodiment of the present invention.

[0029] Figure numerals: 10, outer packaging body; 20, tab; 30, battery cell body; 40, positive electrode sheet; 41, positive electrode current collector; 42, positive electrode coating; 43, positive electrode handle; 50, negative electrode sheet; 51, negative electrode current collector; 52, negative electrode coating; 53, negative electrode handle; 60, diaphragm; 61, diaphragm bag; 71, first connecting adhesive layer; 72, second connecting adhesive layer. DETAILED DESCRIPTION

[0030] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the specific embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] It should be noted that when a component / part is referred to as being "set on" another component / part, it may be directly set on the other component / part or there may also be an intermediate component / part. When a component / part is referred to as being "connected / coupled" to another component / part, it may be directly connected / coupled to the other component / part or there may be an intermediate component / part at the same time. The term "connection / coupling" as used herein may include electrical and / or mechanical physical connections / couplings. The term "includes / comprising" as used herein refers to the presence of a feature, step or component / part, but does not exclude the presence or addition of one or more other features, steps or components / parts. The term "and / or" as used herein includes any and all combinations of one or more relevant listed items.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application. In addition, in the description of this application, the terms "first", "second", etc. are only used to describe purposes and to distinguish similar objects. There is no sequential order between the two, nor can they be understood to indicate or imply relative importance. In addition, in the description of this application, unless otherwise stated, the meaning of "plurality" is two or more.

[0033] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways to implement the methods, devices, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0034] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0035] The terms used herein are intended only to describe various examples and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular is intended to include the plural. The terms "comprise," "include," and "have" list the presence of stated features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0036] Due to manufacturing techniques and / or tolerances, variations in the shapes shown in the drawings may occur. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include changes in shapes that occur during manufacturing.

[0037] First embodiment like Figures 1 to 3 FIG. 1 shows an ultra-thin battery that is not wrinkled when bent according to the first embodiment of the present invention.

[0038] refer to Figure 2 The ultra-thin battery includes an outer packaging body 10, a tab 20, and a cell body 30. The cell body 30 is a laminated structure and is disposed within the outer packaging body 10. The tab 20 is connected to the cell body 30 and extends outside the outer packaging body 10.

[0039] refer to Figure 1The battery cell body 30 includes a positive electrode sheet 40, a negative electrode sheet 50, and a separator 60 separated from the positive electrode sheet 40 and the negative electrode sheet 50. By way of example and not limitation, the positive electrode sheet 40 is provided with two layers, and the negative electrode sheet 50 is provided with three layers, one more layer than the positive electrode sheet 40. The separator 60 is separated and provided between two adjacent positive electrode sheets 40 and negative electrode sheets 50. Exemplarily, the positive electrode sheet 40 and the negative electrode sheet 50 are configured in a rectangular shape, the length and width of the negative electrode sheet 50 are larger than the length and width of the positive electrode sheet 40, the length, width and thickness of each positive electrode sheet 40 are consistent, and the length and width of each negative electrode sheet 50 are consistent. Each positive electrode sheet 40 is composed of a positive electrode current collector 41 coated with a positive electrode coating 42 on both sides. The topmost negative electrode sheet 50 and the bottommost negative electrode sheet 50 are composed of a negative electrode current collector 51 coated on one side with a negative electrode coating 52, while the remaining negative electrode sheets 50 are composed of a negative electrode current collector 51 coated on both sides with a negative electrode coating 52. Conventionally, but not limitingly, the positive electrode current collector 41 of each positive electrode sheet 40 is provided with a positive electrode handle 43, and the negative electrode current collector 51 of each negative electrode sheet 50 is provided with a negative electrode handle 53. The positive electrode handles 43 of each positive electrode sheet 40 are welded to each other and to one electrode tab 20, and the negative electrode handles 53 of each negative electrode sheet 50 are welded to each other and to another electrode tab 20. Each electrode tab 20 is provided with the same adhesive material as the outer packaging 10, thereby hermetically connecting the electrode tab 20 to the outer packaging 10. Conventionally, but not limitingly, the outer packaging 10 is an aluminum-plastic packaging, wherein the plastic portion is made of PP. The electrode tabs 20 are also provided with PP adhesive, thereby connecting the electrode tabs 20 to the outer packaging 10.

[0040] To achieve the objectives of the present invention, first connecting adhesive layers 71 are provided on the top and bottom of the battery cell body 30. Specifically, a negative electrode coating 52 is provided on the lower side of the topmost negative electrode sheet 50, and the upper side of the topmost negative electrode sheet 50 is connected to the first connecting adhesive layer 71. A negative electrode coating 52 is provided on the upper side of the bottommost negative electrode sheet 50, and the lower side of the bottommost negative electrode sheet 50 is connected to the first connecting adhesive layer 71. When the outer packaging body 10 wraps around the battery cell body 30, it is connected to the first connecting adhesive layer 71 on the upper side of the topmost negative electrode sheet 50 and to the first connecting adhesive layer 71 on the lower side of the bottommost negative electrode sheet 50.

[0041] To achieve the purpose of the present invention, on the other hand, the upper and lower sides of the separator 60 are respectively provided with a second connecting adhesive layer 72. Each separator 60 is connected to the positive electrode sheet 40 and the negative electrode sheet 50 on its upper and lower sides respectively through the second connecting adhesive layer 72 on the upper and lower sides.

[0042] To achieve the objectives of the present invention, the cell body 30 is configured as a flexible, ultra-thin structure. Specifically, the thickness of the cell body 30 does not exceed 1.2 mm. To this end, the total thickness of the positive electrode sheet 40, the negative electrode sheet 50, the first connecting adhesive layer 71, and the separator 60 coated with the second connecting adhesive layer 72 does not exceed 1.2 mm.

[0043] refer to Figure 3 When the two sides of the ultra-thin battery described in this embodiment are bent and twisted downward after being formed, the upper side of the outer packaging body 10 is stretched, pulling the top first connecting adhesive layer 71 to stretch. After being cushioned by the top first connecting adhesive layer 71, the top of the battery cell body 30 is stretched. Similarly, the lower side of the outer packaging body 10 is compressed, pulling the bottom first connecting adhesive layer 71 to compress. After being cushioned by the bottom first connecting adhesive layer 71, the top of the battery cell body 30 is compressed. In the battery cell body 30, since the positive electrode sheet 40 and the negative electrode sheet 50 are separated by the separator 60, the upper and lower sides of the separator 60 are respectively connected to the positive electrode sheet 40 and the negative electrode sheet 50 through the second connecting adhesive layer 72, so that the battery cell body 30 forms a structure in which the positive electrode sheet 40 and the negative electrode sheet 50 are linked. When the battery cell body 30 is bent, the upper positive electrode sheet 40 and the negative electrode sheet 50 are stretched synchronously, and the lower positive electrode sheet 40 and the negative electrode sheet 50 are compressed synchronously, so that when the battery is bent, there will be no misalignment or wrinkles between the electrode sheets, avoiding the occurrence of lithium deposition and short circuit. The bending force is transmitted between the electrode sheets, avoiding the rupture of individual electrode sheets and damage to the battery.

[0044] According to a first embodiment of the present invention, there is also provided a method for manufacturing an ultra-thin battery that is not wrinkled when bent or twisted. The method comprises the following steps: (1) The positive electrode sheet 40, the negative electrode sheet 50, the separator 60, and the first connecting adhesive layer 71 are manufactured according to the ultra-thin battery structure in the above embodiment by using processes such as batching, coating, rolling, and sheeting. A second connecting adhesive layer 72 is coated on both sides of the separator 60. The first connecting adhesive layer 71 is made of pressure-sensitive rubber and has only single-sided adhesive properties before heating, but becomes double-sided adhesive after heating and cooling. The second connecting adhesive layer 72 is formed by coating polyvinylidene fluoride or polymethyl methacrylate on the surface of the separator 60 and becomes adhesive and ductile after heating.

[0045] (2) Lamination: Using a lamination process, the positive electrode sheet 40, the negative electrode sheet 50, and the separator 60 are stacked to form the battery cell body 30. The negative electrode has one more layer than the positive electrode. The thickness of the battery cell body 30 does not exceed 1.2 mm. After lamination, the battery cell body 30 is hot pressed. The second connecting adhesive layer 72 on the surface of the separator 60 melts and adheres to the positive electrode sheet 40 and the negative electrode sheet 50 respectively.

[0046] (3) Welding of the tabs 20 : Using an ultrasonic welder, weld one tab 20 to the positive electrode handle 43 of each positive electrode sheet 40 , and weld the other tab 20 to the negative electrode handle 53 of each negative electrode sheet 50 .

[0047] (4) Packaging: affix a first connecting adhesive layer 71 to the top and bottom of the battery cell body 30, and then package it into an outer packaging body 10 of aluminum-plastic film.

[0048] (5) Baking: Baking at a temperature of 90°C for 12 hours in a vacuum oven. The PP adhesive provided on the tab 20 is connected to the outer packaging body 10, the packaging edge of the outer packaging body 10 is connected, and the first connecting adhesive layer 71 is connected to the inner side of the outer packaging body 10.

[0049] (6) Inject electrolyte at a rate of 3.8 g / Ah.

[0050] (7) Formation: Pressurized formation is carried out in an environment with a temperature of 45°C and a pressure of 0.5 MPa. After formation, the battery is vacuum-pumped to discharge excess electrolyte and gases generated by the formation.

[0051] (8) Forming, cutting off the excess material of the outer packaging body 10, and folding the outer packaging body 10.

[0052] (9) Battery testing and battery packaging.

[0053] Thus, the diaphragm 60 is tightly connected to the upper and lower positive electrode sheets 40 and the negative electrode sheets 50 through the second connecting adhesive layer 72 after hot pressing and baking treatment, so that the battery cell body 30 is tightly connected to the outer packaging body 10 through the first connecting adhesive layer 71. After formation, the battery is vacuum-sucked to reduce the internal space of the outer packaging body, thereby further improving the overall bending and torsional performance and safety of the battery.

[0054] Second embodiment like Figure 4 and Figure 5 The figure shows an ultra-thin battery that bends and wrinkles without wrinkles according to a second embodiment of the present invention. In addition to the outer packaging body 10, tabs 20, and cell body 30 structures described in the first embodiment, and the cell body 30 comprising a positive electrode sheet 40, a negative electrode sheet 50, and a first connecting adhesive layer 71, in this ultra-thin battery, two separators 60 are connected at their edges to form a separator bag 61. The positive electrode sheet 40 is encased within the separator bag 61, and a second connecting adhesive layer 72 is provided on both the outer and inner sides of the separator bag 61. Specifically, the positive electrode sheet 40 has three layers, while the negative electrode sheet 50 has four layers, one more than the positive electrode sheet 40. Each positive electrode sheet 40 is composed of a positive electrode current collector 41 coated on both sides with a positive electrode coating 42. Each positive electrode sheet 40 is encased within the separator bag 61. The topmost and bottommost negative electrode sheets 50 have negative electrode coating 52 applied to one side, while the remaining negative electrode sheets 50 have negative electrode coating 52 applied to both sides.

[0055] Therefore, reference Figure 6The positive and negative electrode sheets 40 and 50 in the negative electrode sheet 50 and separator 60 bags are alternately stacked in sequence, so that a separator 60 is provided between adjacent positive and negative electrode sheets 40 and 50, and a first connecting adhesive layer 71 is provided on the top and bottom of the battery cell body 30. The second connecting adhesive layers 72 on the inner and outer sides of the separator bag 61 are respectively connected to the upper and lower sides of the positive electrode sheet 40, and the second connecting adhesive layers 72 on the outer and inner sides of the separator bag 61 are respectively connected to the upper and lower negative electrode sheets 50.

[0056] The first embodiment of the present invention also relates to a method for manufacturing an ultra-thin battery that does not wrinkle when bent or twisted. In addition to the manufacturing method described in the first embodiment, the main difference is that the separator 60 is formed into a separator bag 61, and the positive electrode sheet 40 is packaged within the separator bag 61. A second connecting adhesive layer 72 is applied to both sides of the separator 60 on the separator bag 61.

[0057] refer to Figure 7 The three-dimensional structure of the ultra-thin battery after molding according to various embodiments of the present invention. Since the ultra-thin battery is only about 1.2 mm thick, it can bend and twist. Furthermore, since the cell body 30 and the outer packaging body 10 are connected by the first connecting adhesive layer 71, each positive electrode sheet 40 is connected to the second connecting adhesive layer 72 on the separator 60, and each negative electrode sheet 50 is connected to the second connecting adhesive layer 72 on the separator 60, the ultra-thin battery can withstand bending and twisting deformation while still maintaining a long service life.

[0058] According to the ultra-thin batteries of various embodiments of the present invention, the changes in voltage, internal resistance, and capacity of the ultra-thin batteries before and after the bending and torsion test are shown in Table 1 below.

[0059]

[0060] The test data in Table 1 shows that after 7,000 bends and twists, the voltage of the ultra-thin batteries remained almost unchanged compared to before the test, and the internal resistance of the ultra-thin batteries remained almost unchanged or slightly decreased. After 10,000 bends and twists, the voltage of the ultra-thin batteries decreased slightly compared to before the test, and only some of the ultra-thin batteries showed an increase in internal resistance. The 0.5C recovery capacity was roughly the same as before the bends and twists.

[0061] The capacity retention and cycle number curves of the ultra-thin batteries according to various embodiments of the present invention before and after the bending and torsion test are as follows: Figure 8 shown.

[0062] Depend on Figure 8 The test curve shows that after 10,000 bending and twisting cycles, the ultra-thin battery of this embodiment maintained comparable capacity retention compared to the unbent battery before 250 cycles of charge and discharge. Between 250 and 500 cycles of charge and discharge, the capacity retention of the ultra-thin battery of this embodiment decreased slightly compared to the unbent battery.

[0063] The above embodiments primarily illustrate the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. An ultra-thin battery that does not wrinkle when bent or twisted, comprising an outer packaging body (10), a laminated battery cell body (30) disposed within the outer packaging body (10), and a tab (20) connected to the battery cell body (30) and extending outside the outer packaging body (10), characterized in that: The battery cell body (30) includes a positive electrode sheet (40), a negative electrode sheet (50), and a separator (60) disposed between the positive electrode sheet (40) and the negative electrode sheet (50); The top and bottom of the battery cell body (30) are respectively provided with a first connecting adhesive layer (71), and the top and bottom of the battery cell body (30) are connected to the inner side of the outer packaging body (10) through the first connecting adhesive layer (71); The upper and lower sides of the diaphragm (60) are respectively provided with second connecting adhesive layers (72), and the upper and lower sides of the diaphragm (60) are respectively connected to the positive electrode sheet (40) and the negative electrode sheet (50) through the second connecting adhesive layers (72).

2. The ultra-thin battery that does not wrinkle when bent or twisted according to claim 1, characterized in that: There are more than two positive electrode sheets (40) and more than two negative electrode sheets (50), respectively, and the number of the negative electrode sheets (50) is one layer more than the number of the positive electrode sheets (40).

3. The ultra-thin battery that does not wrinkle when bent or twisted according to claim 2, characterized in that: The uppermost negative electrode sheet (50) and the lowermost negative electrode sheet (50) are composed of a negative electrode current collector (51) coated with a negative electrode coating (52) on one side, the lower side of the uppermost negative electrode sheet (50) is provided with a negative electrode coating (52), the upper side of the uppermost negative electrode sheet (50) is connected to the first connecting adhesive layer (71), the upper side of the lowermost negative electrode sheet (50) is provided with a negative electrode coating (52), the lower side of the lowermost negative electrode sheet (50) is connected to the first connecting adhesive layer (71), and the remaining negative electrode sheets (50) are composed of a negative electrode current collector (51) coated with a negative electrode coating (52) on both sides; the positive electrode sheet (40) is composed of a positive electrode current collector (41) coated with a positive electrode coating (42) on both sides.

4. The ultra-thin battery that does not wrinkle when bent or twisted according to claim 3, characterized in that: The positive electrode collector (41) of each positive electrode sheet (40) is provided with a positive electrode handle (43), and each positive electrode handle (43) is connected to one electrode tab (20) after being welded to each other. The negative electrode collector (51) of each negative electrode sheet (50) is provided with a negative electrode handle (53), and each negative electrode handle (53) is connected to another electrode tab (20) after being welded to each other.

5. The ultra-thin battery that does not wrinkle when bent or twisted according to claim 2, characterized in that: The two diaphragms (60) are connected at their edges to form a diaphragm bag (61), the positive electrode sheet (40) is wrapped in the diaphragm bag (61), and the outer two side surfaces and the inner two side surfaces of the diaphragm bag (61) are respectively provided with a second connecting adhesive layer (72).

6. The ultra-thin battery that does not wrinkle when bent or twisted according to any one of claims 1 to 5, characterized in that: The first connecting adhesive layer (71) is a sheet-like structure made of pressure-sensitive rubber.

7. The ultra-thin battery that does not wrinkle when bent or twisted according to any one of claims 1 to 5, characterized in that: The second connecting adhesive layer (72) is formed by coating polyvinylidene fluoride or polymethyl methacrylate on the surface of the diaphragm (60).

8. The ultra-thin battery that does not wrinkle when bent or twisted according to any one of claims 1 to 5, characterized in that: The thickness of the battery cell body (30) is less than or equal to 1.2 mm.

9. The method for manufacturing a wrinkle-free ultra-thin battery according to any one of claims 1 to 8, wherein: The manufacturing method comprises the steps of: A positive electrode sheet (40), a negative electrode sheet (50), a separator (60) and a first connecting adhesive layer are manufactured; wherein the surface of the separator (60) is coated with a second connecting adhesive layer; The positive electrode sheet (40), the negative electrode sheet (50) and the separator (60) are stacked to form a battery cell body (30), and the battery cell body (30) is subjected to a heat pressing process so that the second connecting adhesive layer of the separator (60) is connected to the positive electrode sheet (40) and the negative electrode sheet (50) respectively; Welding the tab (20) to the battery cell body (30); A first connecting adhesive layer is provided on the top and bottom of the battery cell body (30), and then the battery cell body (30) is packaged in an outer packaging body (10), and the first connecting adhesive layer is respectively connected to the battery cell body (30) and the outer packaging body (10) through baking; The battery is manufactured through liquid injection, formation and molding; wherein, after formation, the battery is vacuum-pumped to discharge excess electrolyte and gas generated by formation.

10. The method for manufacturing a wrinkle-free ultra-thin battery according to claim 9, wherein: In the baking step, the temperature is set at 85-95°C and the vacuum baking is carried out for 10-14 hours; In the injection step, the electrolyte is injected at a rate of 3 to 4.5 g / Ah; In the formation step, the battery is charged at a constant current, left to stand to form the SEI film, and then pressurized at a temperature of 45°C and a pressure of 0.5 MPa. In the forming step, the remaining material of the outer packaging body (10) is cut off, and the outer packaging body (10) is folded.

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