Flexible battery and preparation method thereof

Abstract

The present invention relates to the field of battery technology, and provides a method for preparing a flexible battery, including three steps S1-S3. A flexible battery is also provided, including a flexible battery body, the flexible battery body including an electrolyte, an electrode assembly, and an outer packaging film for encapsulating the electrolyte and the electrode assembly, the flexible battery body is bent in sequence to form a plurality of bending points, and there is a bending gap between two adjacent bending points on the same side, and each of the bending gaps is filled with elastic glue. On the one hand, the present invention bends the flat flexible battery body multiple times in the same direction. After forming, these bending structures can eliminate the stress generated during bending during use, thereby improving the life of the flexible battery. On the other hand, the filled elastic glue can serve as a stress bearer during stretching and contraction, so that the internal structure of the flexible battery is not affected by stretching and contraction during bending, so that the electrical performance and sealing of the flexible battery are not affected by bending, thereby improving the bending performance.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a flexible battery and a preparation method thereof. Background Art

[0002] In recent years, new electronic products have become more and more popular among consumers, such as smart helmets, smart sports shoes, foldable mobile phones, foldable tablets, etc. However, due to the limitation that existing lithium batteries cannot maintain good electrical and sealing properties after multiple bends, the curved parts required for the use of these electronic products cannot be filled with batteries, resulting in the problem of short battery life. Summary of the invention

[0003] The purpose of the present invention is to provide a flexible battery and a preparation method thereof. On the one hand, a flat flexible battery body is bent multiple times in the same direction. After forming, these bent structures can eliminate the stress generated during bending during use, thereby improving the life of the flexible battery. On the other hand, the filled elastic glue can serve as a stress bearer during stretching and contraction, so that the internal structure of the flexible battery is not affected by stretching and contraction during bending, thereby making the electrical properties and sealing of the flexible battery not affected by bending, thereby improving the bending performance.

[0004] To achieve the above object, the embodiment of the present invention provides the following technical solution: a method for preparing a flexible battery, comprising the following steps:

[0005] S1, encapsulating the electrolyte and the electrode assembly in an outer packaging film to obtain a flat flexible battery body;

[0006] S2, bending the flexible battery body multiple times in the same direction;

[0007] S3, filling elastic glue in the bending gap of the flexible battery body after bending, and leading out the positive electrode sheet and the negative electrode sheet at the end of the flexible battery body.

[0008] Further, in the S2 step, the specific bending method is: taking one side of the flexible battery body as the starting side, and taking the side of the flexible battery body relative to the starting side as the ending side, and starting to bend the flexible battery body in a serpentine form at the starting side along the direction from the starting side to the ending side, until it stops when it is bent to the ending side of the flexible battery body.

[0009] Furthermore, in the step S1, the flat flexible battery body is in the shape of a long strip, the thickness of which is controlled between 0.5 and 3 mm, and the specified bending length is controlled between 1 and 10 mm.

[0010] Furthermore, after being bent, the thickness of the flexible battery body is controlled between 1 and 20 mm, and the minimum bending gap is controlled between 0.1 and 2 mm.

[0011] Furthermore, the elastic rubber includes styrene-butadiene rubber, butadiene rubber, isoprene rubber or silicone rubber.

[0012] Furthermore, in the S1 step, the outer packaging film is prepared before packaging, and the preparation of the outer packaging film is specifically as follows: a first glue layer is coated on the upper surface of the metal layer, and then a nylon layer is arranged on the first glue layer, a second glue layer is coated on the lower surface of the metal layer, and then a PP layer is arranged on the second glue layer.

[0013] Furthermore, the PP layer is close to the electrode assembly.

[0014] Furthermore, in the step S1, the electrode assembly is prepared before packaging. The preparation of the electrode assembly is specifically as follows: positive electrode active materials are coated on the upper and lower surfaces of the positive electrode collector, and negative electrode active materials are coated on the upper and lower surfaces of the negative electrode collector, and the positive electrode collector coated with the positive electrode active material and the negative electrode collector coated with the negative electrode active material are separated by a separator.

[0015] An embodiment of the present invention provides another technical solution: a flexible battery, comprising a flexible battery body, wherein the flexible battery body comprises an electrolyte, an electrode assembly and an outer packaging film for encapsulating the electrolyte and the electrode assembly, wherein the flexible battery body is bent in sequence to form a plurality of bending points, and a bending gap is provided between two adjacent bending points on the same side, and each of the bending gaps is filled with elastic glue.

[0016] Furthermore, the bending points located on the same side are located in the same plane.

[0017] Compared with the prior art, the beneficial effects of the present invention are: on the one hand, the flat flexible battery body is bent multiple times in the same direction. After forming, these bent structures can eliminate the stress generated during bending during use, thereby improving the life of the flexible battery; on the other hand, the filled elastic glue can serve as a stress bearer during stretching and contraction, so that the internal structure of the flexible battery is not affected by stretching and contraction during bending, thereby making the electrical properties and sealing of the flexible battery not affected by bending, thereby improving the bending performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flowchart of a method for preparing a flexible battery provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the overall structure of a flexible battery provided by an embodiment of the present invention;

[0020] Figure 3 A side view of a flat flexible battery body of a flexible battery provided by an embodiment of the present invention;

[0021] Figure 4 A three-dimensional diagram of a flat flexible battery body of a flexible battery provided by an embodiment of the present invention;

[0022] Figure 5 A side view of a flexible battery body after bending provided by an embodiment of the present invention;

[0023] Figure 6 A three-dimensional diagram of a flexible battery body after bending of a flexible battery provided by an embodiment of the present invention;

[0024] Figure 7 A side view of a flexible battery body after being bent and filled with elastic glue provided by an embodiment of the present invention;

[0025] Figure 8 A three-dimensional image of a flexible battery body after being bent and filled with elastic glue provided by an embodiment of the present invention;

[0026] Fig. 9 A side view of a bent form of a flexible battery provided by an embodiment of the present invention;

[0027] Fig.10 A three-dimensional diagram of a bent state of a flexible battery provided by an embodiment of the present invention;

[0028] Fig.11 for Figure 4 An enlarged view of the dotted circle;

[0029] Fig.12 for Fig.11 An enlarged view of the dotted circle;

[0030] Fig.13 for Figure 5 Enlarged image of the black box in the middle;

[0031] In the accompanying drawings: 101-flexible battery body; 102-elastic glue; 103-first bending gap; 104-second bending gap; 105-first bending point; 106-second bending point; 301-nylon layer; 302-first glue layer; 303-metal layer; 304-second glue layer; 305-PP layer; 401-positive electrode active material; 402-positive electrode current collector; 403-diaphragm; 404-negative electrode active material; 405-negative electrode current collector. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] See also Figure 1-12 An embodiment of the present invention provides a method for preparing a flexible battery, comprising the following steps: S1, encapsulating an electrolyte and an electrode assembly in an outer packaging film to obtain a flat flexible battery body 101; S2, bending the flexible battery body 101 multiple times in the same direction; S3, filling an elastic glue 102 in the bending gap of the flexible battery body 101 after bending, and leading out a positive electrode sheet and a negative electrode sheet at the end of the flexible battery body 101. In the present embodiment, the flexible battery body 101 prepared in step S1 is the same as the existing flexible battery body 101, which is a flat long strip. The next step is the key to the present embodiment. The flat long strip flexible battery body 101 is bent multiple times in the same direction to form multiple bending points. At this point, the preparation of the flexible battery is half completed. Through these bending structures, the stress generated during bending can be eliminated during the later use of the flexible battery, such as during bending, thereby increasing the life of the flexible battery. In the prior art, there is a flexible battery that only bends the outer packaging film. The difficulty of preparing this flexible battery is much less than the overall bending in the present embodiment, and during use, its resistance to stress is also much weaker than the flexible battery in the present embodiment. Then, after bending, there is a bending gap between two adjacent bending points on the same side, such as Figure 2As shown, for the convenience of description, on the upper side of the flexible battery body 101, the bending gap between two adjacent bending points is defined as a first bending gap 103, and all the bending points on this side are also defined as first bending points 105. On the lower side of the flexible battery body 101, the bending gap between two adjacent bending points is defined as a second bending gap 104. Similarly, all the bending points on this side are also defined as second bending points 106. Elastic glue 102 is filled in these first bending gaps 103 and these second bending gaps 104. After the elastic glue 102 solidifies, elastic glue surfaces are formed on the upper and lower surfaces of the flexible battery body 101. When the prepared flexible battery is stretched or contracted during use, the elastic glue 102 first receives the impact of the stretching or contraction force. As a bearing body for stretching or contraction, when the size of each bending gap of the flexible battery changes, it will not affect the internal structure. In this way, the electrical performance and sealing performance of the flexible battery can be ensured not to be affected by bending, thereby improving the bending performance.

[0035] The following are specific embodiments:

[0036] As an optimization solution of the embodiment of the present invention, please refer to Figure 2 In the step S2, the specific bending method is: take one side of the flexible battery body 101 as the starting side, and take the side of the flexible battery body 101 relative to the starting side as the ending side, and start bending the flexible battery body 101 in a serpentine form at the starting side along the direction from the starting side to the ending side, until it stops when it is bent to the ending side of the flexible battery body 101. In this embodiment, the flexible battery body 101 is first defined as a long strip, and is bent in a serpentine form. The bending is continuous bending, and the bending direction is the length direction of the flexible battery body 101. After the bending is completed, each first bending point 105 located on the upper side of the flexible battery body 101 is a crest, and each second bending point 106 located on the lower side of the flexible battery body 101 is a trough. Of course, according to the requirements of the actual wearable device, it can also be bent discontinuously, for example, it can be bent at intervals in the middle, or it will not continue to bend on the starting side and / or the ending side, and it will extend horizontally.

[0037] As an optimization solution of the embodiment of the present invention, please refer to Figure 3 and Figure 4In the step S1, the flat flexible battery body 101 is in the shape of a long strip, and its thickness T0 is controlled between 0.5 and 3 mm, and the length L0 specified for bending is controlled between 1 and 10 mm. The length specified for bending is determined according to the actual battery design to determine how much length is required for bending. In this embodiment, in order to ensure that the thickness of the flexible battery body 101 after bending is not too thick, so as to affect the application in various electronic products, the thickness T0 of the flexible battery body 101 is controlled between 0.5 and 3 mm, and the length L0 specified for bending is controlled between 1 and 10 mm. Preferably, when the thickness T0 of the flexible battery body 101 is 2 mm and the length L0 specified for bending is 5 mm, a flexible battery body 101 with the best toughness and suitable for the needs of most electronic products can be obtained. T0 and L0 in this embodiment are both values ​​before bending.

[0038] As an optimization solution of the embodiment of the present invention, please refer to Figure 5 and Figure 6 , the thickness T of the flexible battery body 101 after bending is controlled between 1 and 20 mm, and the minimum bending gap G (or the inner diameter R of the bending point) is controlled between 0.1 and 2 mm. In this embodiment, the thickness of the flexible battery body 101 after bending and the size of the bending gap are also controlled to be the same as the purpose of controlling the thickness of the electrode assembly. Preferably, when the thickness T of the flexible battery body 101 after bending is 10 mm and the bending gap G is at least 1 mm, a flexible battery body 101 with the best toughness and suitable for the needs of most electronic products can be obtained. T and L are both values ​​before bending. Preferably, the relationship between T, T0, L, and L0 is as follows: T = L0-π*R+2R+2*T0 (L0 minus π times R plus 2 times T0), L = π*(R+T0 / 2).

[0039] As an optimization solution of the embodiment of the present invention, the elastic glue 102 includes a polymer material with elastomeric properties, including styrene-butadiene rubber, butadiene rubber, isoprene rubber, silicone rubber, etc. The elastic glue has good elasticity, and can be stretched / contracted with the external force when receiving an external force, and can quickly return to a state and size close to the original state when the external force is removed. In addition, the elastic glue also has good wear resistance / heat resistance / cold resistance / aging resistance, etc.

[0040] As an optimization solution of the embodiment of the present invention, please refer to Fig.11 and Fig.12In the step S1, the outer packaging film is prepared before packaging. The outer packaging film is prepared specifically as follows: a first glue layer 302 is coated on the upper surface of the metal layer 303, and then a nylon layer 301 is placed on the first glue layer 302, a second glue layer 304 is coated on the lower surface of the metal layer 303, and then a PP layer 305 is placed on the second glue layer 304. Preferably, the PP layer 305 is close to the electrode assembly. In this embodiment, the metal layer 303 is an aluminum-plastic film intermediate layer, which is a base material and plays a waterproof and barrier role. It can also be made of copper, phosphor bronze, aluminum bronze, and various copper alloys, copper-nickel-silicon alloys, etc. The first glue layer 302 and the second glue layer 304 can be made of one or more of silicone, polyphthalate, modified polypropionic acid, modified polyacetic acid or polyurethane. The PP layer 305 is a polypropylene layer, which is a thermoplastic resin that contacts the electrolyte and is a heat-sealable film with high stability, strong corrosion resistance, and good anti-permeability.

[0041] As an optimization solution of the embodiment of the present invention, please refer to Fig.11 and Fig.12 In the step S1, the electrode assembly is prepared before packaging. The electrode assembly is prepared specifically as follows: the positive electrode active material 401 is coated on the upper and lower surfaces of the positive electrode current collector 402, and the negative electrode active material 404 is coated on the upper and lower surfaces of the negative electrode current collector 405, and the positive electrode current collector 402 coated with the positive electrode active material 401 and the negative electrode current collector 405 coated with the negative electrode active material 404 are separated by the separator 403. In this embodiment, the electrode assembly is the core part of the battery, which is composed of the positive and negative electrode current collectors 405 coated with active materials and the separator 403. The current collector used is a metal current collector, which has a certain degree of flexibility. After one-time bending and forming, after filling the elastic glue 102, the metal current collector will be protected by the elastic glue 102, and the metal current collector will not be bent repeatedly when bent. The separator 403 used plays the role of blocking separators and electrons, and can be made of PP, PE or a composite of PP and PE.

[0042] In the performance test of the flexible battery prepared according to this method, after repeated bending, its capacity and retention rate are shown in the following table:

[0043]

[0044] It can be seen that the flexible battery prepared by this method has a very high retention rate after repeated bending.

[0045] Embodiment 2:

[0046] The contents of this embodiment and embodiment 1 can be referenced to each other. Figure 2-12An embodiment of the present invention provides a flexible battery, including a flexible battery body 101, wherein the flexible battery body 101 includes an electrolyte, an electrode assembly, and an outer packaging film for encapsulating the electrolyte and the electrode assembly, wherein the flexible battery body 101 is bent in sequence to form a plurality of bending points, and a bending gap is provided between two adjacent bending points on the same side, and each of the bending gaps is filled with elastic glue 102. In this embodiment, initially the flexible battery body 101 is the same as the existing flexible battery body 101, which is a flat long strip. Next, the flat long strip flexible battery body 101 is bent multiple times in the same direction to form multiple bending points. At this point, the preparation of the flexible battery is halfway completed. Through these bending structures, the stress generated during bending can be eliminated during the later use of the flexible battery, such as during bending, thereby increasing the life of the flexible battery. In the prior art, there is a flexible battery that only bends the outer packaging film. The difficulty of preparing this flexible battery is much less than the overall bending in this embodiment, and during use, its resistance to stress is also much weaker than that of the flexible battery in this embodiment. Then, after bending, there is a bending gap between two adjacent bending points on the same side, such as Figure 2 As shown, for the convenience of description, on the upper side of the flexible battery body 101, the bending gap between two adjacent bending points is defined as a first bending gap 103, and all the bending points on this side are also defined as first bending points 105. On the lower side of the flexible battery body 101, the bending gap between two adjacent bending points is defined as a second bending gap 104. Similarly, all the bending points on this side are also defined as second bending points 106. Elastic glue 102 is filled in these first bending gaps 103 and these second bending gaps 104. After the elastic glue 102 solidifies, elastic glue surfaces are formed on the upper and lower surfaces of the flexible battery body 101. When the prepared flexible battery is stretched or contracted during use, the elastic glue 102 first receives the impact of the stretching or contraction force. As a bearing body for stretching or contraction, when the size of each bending gap of the flexible battery changes, it will not affect the internal structure. In this way, the electrical performance and sealing performance of the flexible battery can be ensured not to be affected by bending, thereby improving the bending performance. The internal structure includes the outer packaging film and the electrode assembly. Fig.11 and Fig.12 The outer packaging film includes a nylon layer 301, a first glue layer 302, a metal layer 303, a second glue layer 304 and a PP layer 305 stacked in sequence, and the electrode assembly includes a positive electrode collector 402, a separator 403 and a negative electrode collector 405 stacked in sequence. The upper and lower surfaces of the positive electrode collector 402 are only coated with positive electrode active materials 401, and the upper and lower surfaces of the negative electrode collector 405 are both coated with negative electrode active materials 404. The PP layer 305 is close to the electrode assembly.

[0047] As an optimization solution of the embodiment of the present invention, please refer to Figure 2 , the ends of the flexible battery body 101 are led out with a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are both connected to the electrode assembly. In this embodiment, leading out the positive and negative electrode sheets supports a complete flexible battery. Preferably, the flexible battery body 101 is in the shape of an elongated strip, and one end of the flexible battery body 101 has an extension portion extending along the length direction of the flexible battery body 101, and the positive electrode sheet and the negative electrode sheet are both arranged on the extension portion, which can cater to the production of subsequent wearable devices. The end of the flexible battery body 101 can be extended horizontally to facilitate the installation of the positive electrode sheet and the negative electrode sheet. Of course, if necessary, it can also be extended in other directions, and the positive and negative electrode sheets may not be arranged at the same end.

[0048] As an optimization solution of the embodiment of the present invention, please refer to Figure 2 , Figure 7 and Figure 8 , the bending points on the same side are located in the same plane. In this embodiment, in order to ensure that the prepared flexible battery meets the installation requirements of the wearable device, the highest point of each crest is limited to the same level, and the lowest point of each trough is also limited to the same level.

[0049] As an optimization solution of the embodiment of the present invention, please refer to Figure 2 , Figure 7 and Figure 8 , the highest points of the elastic glue 102 on the same side are located in the same plane. In this embodiment, as with the above-mentioned requirements for the bending point, ensuring that the elastic glue 102 is in the same plane also facilitates the installation of the wearable device.

[0050] As an optimization solution of the embodiment of the present invention, please refer to Figure 5-8 , each of the first bending gaps 103 and each of the second bending gaps 104 are at least between 0.1 and 2.0 mm. In this embodiment, the thickness of the flexible battery body 101 after bending and the size of the bending gap are controlled to ensure that the thickness of the flexible battery body 101 after bending is not too thick to affect the application in various electronic products. Preferably, when the thickness of the flexible battery body 101 after bending is 10 mm and the bending gap is at least 1 mm, a flexible battery body 101 with the best toughness and suitable for the needs of most electronic products can be obtained.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a flexible battery, characterized in that: The steps include: S1, encapsulating the electrolyte and the electrode assembly in an outer packaging film to obtain a flat flexible battery body; S2, bending the flexible battery body multiple times in the same direction; S3, filling elastic glue in the bending gap of the flexible battery body after bending, and leading out the positive electrode sheet and the negative electrode sheet at the end of the flexible battery body, In the step S1, the flat flexible battery body is in the shape of a long strip, the thickness T0 of which is controlled between 0.5 and 3 mm, and the bending length L0 is controlled between 1 and 10 mm. After bending, the thickness T of the flexible battery body is controlled between 1 and 20 mm, and the minimum bending gap G or the inner diameter R of the bending point is controlled between 0.1 and 2 mm. T=L0-π*R+2R+2*T0, L=π*(R+T0 / 2).

2. The method for preparing a flexible battery according to claim 1, characterized in that: In the S2 step, the specific bending method is: taking one side of the flexible battery body as the starting side, and taking the side of the flexible battery body relative to the starting side as the ending side, and starting to bend the flexible battery body in a serpentine form at the starting side along the direction from the starting side to the ending side, until it stops when it is bent to the ending side of the flexible battery body.

3. The method for preparing a flexible battery according to claim 1, characterized in that: The elastic rubber includes styrene-butadiene rubber, butadiene rubber, isoprene rubber or silica gel.

4. The method for preparing a flexible battery according to claim 1, characterized in that: In the S1 step, the outer packaging film is prepared before packaging. The preparation of the outer packaging film is specifically as follows: a first glue layer is coated on the upper surface of the metal layer, and then a nylon layer is arranged on the first glue layer, a second glue layer is coated on the lower surface of the metal layer, and then a PP layer is arranged on the second glue layer.

5. The method for preparing a flexible battery according to claim 4, characterized in that: The PP layer is close to the electrode assembly.

6. The method for preparing a flexible battery according to claim 1, characterized in that: In the step S1, the electrode assembly is prepared before packaging. The preparation of the electrode assembly is specifically as follows: positive electrode active materials are coated on the upper and lower surfaces of the positive electrode collector, and negative electrode active materials are coated on the upper and lower surfaces of the negative electrode collector, and the positive electrode collector coated with the positive electrode active material and the negative electrode collector coated with the negative electrode active material are separated by a separator.

7. A flexible battery, comprising a flexible battery body, wherein the flexible battery body comprises an electrolyte, an electrode assembly, and an outer packaging film for encapsulating the electrolyte and the electrode assembly, characterized in that: The flexible battery body is prepared by the method described in any one of claims 1 to 6, wherein the flexible battery body is bent in sequence to form a plurality of bending points, and there is a bending gap between two adjacent bending points on the same side, and each bending gap is filled with elastic glue.

8. The flexible battery according to claim 7, characterized in that: The bending points located on the same side are located in the same plane.

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