Curved battery cell and curved lithium battery

Abstract

The present application provides an arc-shaped battery cell and an arc-shaped lithium battery. The arc-shaped battery cell includes a battery cell body, a positive electrode ear and a negative electrode ear. The battery cell body includes a positive electrode sheet, a first hot melt adhesive coating layer, a diaphragm, a second hot melt adhesive coating layer and a negative electrode sheet stacked in sequence. The first hot melt adhesive coating layer and the second hot melt adhesive coating layer are both bonded to the diaphragm, the positive electrode sheet is bonded to the first hot melt adhesive coating layer, and the negative electrode sheet is bonded to the second hot melt adhesive coating layer. The battery cell body is an arc-shaped structure, the positive electrode ear is welded to the positive electrode sheet, and the negative electrode ear is welded to the negative electrode sheet. The arc-shaped battery cell is easy to shape, has good surface flatness and good shaping effect.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to an arc-shaped battery cell and an arc-shaped lithium battery. Background Art

[0002] Since the large-scale production of lithium-ion batteries in the 1990s, they have rapidly occupied many battery fields with their incomparable advantages at this stage, such as small size, large capacity, non-toxic and environmentally friendly, and long service life. They are especially used in portable electronic products. With the updating and development of science and technology, the market has higher and higher requirements for portable electronic products, and the requirements for their power sources have also increased accordingly. For example, the effective space left for batteries in irregular shapes, curves, and arc-shaped mobile phones has become irregular. With the further development of electronic products, smart watches and smart bracelets have been launched one after another. Since they are worn on the wrist when in use, the batteries they are equipped with need to be set according to the use status of the product, so corresponding arc batteries need to be provided.

[0003] However, existing curved batteries have problems such as uneven surface, difficulty in forming, and easy rebound after forming due to internal structural reasons and curvature bending operations. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a curved battery cell and a curved lithium battery which are easy to shape, have good surface flatness and good shaping effect.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A curved battery cell comprises a battery cell body, a positive electrode ear and a negative electrode ear, wherein the battery cell body comprises a positive electrode sheet, a first hot melt adhesive coating layer, a diaphragm, a second hot melt adhesive coating layer and a negative electrode sheet stacked in sequence, wherein the first hot melt adhesive coating layer and the second hot melt adhesive coating layer are both bonded to the diaphragm, the positive electrode sheet is bonded to the first hot melt adhesive coating layer, and the negative electrode sheet is bonded to the second hot melt adhesive coating layer, the battery cell body is an curved structure, the positive electrode ear is welded to the positive electrode sheet, and the negative electrode ear is welded to the negative electrode sheet.

[0007] In one embodiment, the first hot melt adhesive coating layer includes a first diaphragm coating portion and a first pole ear coating portion, the first diaphragm coating portion is bonded to one side of the diaphragm, the first pole ear coating portion is coated on the connection between the positive electrode sheet and the positive pole ear, and the first pole ear coating portion is connected to the first diaphragm coating portion.

[0008] In one embodiment, the second hot melt adhesive coating layer includes a second diaphragm coating portion and a second tab coating portion, the second diaphragm coating portion is bonded to the side of the diaphragm away from the first hot melt adhesive coating layer, the second tab coating portion is coated on the connection between the negative electrode sheet and the negative tab, and the second tab coating portion is connected to the second diaphragm coating portion.

[0009] In one embodiment, the positive electrode sheet includes a positive electrode current collector, and a plurality of first pores are formed on the positive electrode current collector.

[0010] In one embodiment, the diameter of the first pore is 0.1 mm to 0.4 mm.

[0011] In one embodiment, the negative electrode sheet includes a negative electrode current collector, and a plurality of second pores are formed on the negative electrode current collector.

[0012] In one embodiment, the diameter of the second pore is 0.1 mm to 0.4 mm.

[0013] In one embodiment, the sum of the thickness of the first hot melt adhesive coating layer and the second hot melt adhesive coating layer is less than the thickness of the diaphragm.

[0014] In one embodiment, the bending direction of the positive electrode sheet and the negative electrode sheet is consistent with the bending direction of the battery cell body.

[0015] The present application also provides a curved lithium battery, which includes the curved battery cell as described in any of the above embodiments, and also includes a curved aluminum-plastic film, wherein the curved aluminum-plastic film is coated on the outer surface of the curved battery cell.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] 1. The arc-shaped battery cell of the present invention comprises a first hot-melt adhesive coating layer and a second hot-melt adhesive coating layer, wherein the first hot-melt adhesive coating layer is bonded to one side of the diaphragm, and the second hot-melt adhesive coating layer is bonded to the side of the diaphragm away from the first hot-melt adhesive coating layer. When the arc-shaped battery cell is hot-pressed, the first hot-melt adhesive coating layer and the second hot-melt adhesive coating layer have a buffering effect on the stress exerted on the arc-shaped battery cell, thereby preventing the arc-shaped battery cell from breaking or failing to shape during the bending process, thereby making the arc-shaped battery cell easier to shape.

[0018] 2. In the arc-shaped battery cell of the present invention, the first hot-melt adhesive coating layer is bonded to one side of the diaphragm, the second hot-melt adhesive coating layer is bonded to the side of the diaphragm away from the first hot-melt adhesive coating layer, the positive electrode sheet is bonded to the first hot-melt adhesive coating layer, and the negative electrode sheet is bonded to the second hot-melt adhesive coating layer. When the arc-shaped battery cell is subjected to hot-pressing forming operation, the first hot-melt adhesive coating layer and the second hot-melt adhesive coating layer begin to melt and penetrate into the various bending parts of the arc-shaped battery cell, thereby being able to repair the wrinkles generated during the hot-pressing process and making the surface of the arc-shaped battery cell smoother.

[0019] 3. The first hot melt adhesive coating layer and the second hot melt adhesive coating layer in the arc-shaped battery cell of the present invention begin to melt during hot pressing, making the arc-shaped battery cell easier to shape and having better surface flatness. After the arc-shaped battery cell is formed, since the surface of the arc-shaped battery cell returns to room temperature, the first hot melt adhesive coating layer and the second hot melt adhesive coating layer cool and solidify again, so that the arc-shaped battery cell maintains the curvature after forming and is not easy to rebound, thereby achieving a better shaping effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 This is a schematic diagram of the structure of an arc-shaped battery cell in one embodiment;

[0022] Figure 2 for Figure 1 A schematic cross-sectional view of the arc-shaped battery cell structure shown;

[0023] Figure 3 for Figure 1 A partial enlarged schematic diagram of the arc-shaped battery cell structure shown;

[0024] Figure 4 To include Figure 1 A schematic diagram of the structure of a curved lithium battery with a curved cell;

[0025] Figure 5 for Figure 2 The process flow chart of integrated hot pressing and forming of curved lithium batteries is shown. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] The present application provides an arc-shaped battery cell. The arc-shaped battery cell comprises a battery cell body, a positive electrode ear and a negative electrode ear, the battery cell body comprises a positive electrode sheet, a first hot melt adhesive coating layer, a separator, a second hot melt adhesive coating layer and a negative electrode sheet stacked in sequence, the first hot melt adhesive coating layer and the second hot melt adhesive coating layer are both bonded to the separator, the positive electrode sheet is bonded to the first hot melt adhesive coating layer, the negative electrode sheet is bonded to the second hot melt adhesive coating layer, the battery cell body is an arc-shaped structure, the positive electrode ear is welded to the positive electrode sheet, and the negative electrode ear is welded to the negative electrode sheet.

[0030] like Figures 1 to 3 As shown, the arc-shaped battery cell 10 of one embodiment includes a battery cell body 100, a positive electrode ear 200 and a negative electrode ear 300. The battery cell body 100 includes a positive electrode sheet 110, a first hot melt adhesive coating layer 140, a separator 130, a second hot melt adhesive coating layer 150 and a negative electrode sheet 120 stacked in sequence. The first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 are both bonded to the separator 130, the positive electrode sheet 110 is bonded to the first hot melt adhesive coating layer 140, and the negative electrode sheet 120 is bonded to the second hot melt adhesive coating layer 150. The battery cell body 100 is an arc-shaped structure, the positive electrode ear 200 is welded to the positive electrode sheet 110, and the negative electrode ear 300 is welded to the negative electrode sheet 120. It should be noted that the arc-shaped battery cell can be an arc-shaped stacked sheet or an arc-shaped winding core.

[0031] The above-mentioned arc-shaped battery cell 10 includes a first hot-melt adhesive coating layer 140 and a second hot-melt adhesive coating layer 150. The first hot-melt adhesive coating layer 140 is bonded to one side of the diaphragm 130, and the second hot-melt adhesive coating layer 150 is bonded to the side of the diaphragm 130 away from the first hot-melt adhesive coating layer 140. When the arc-shaped battery cell 10 is hot-pressed, the first hot-melt adhesive coating layer 140 and the second hot-melt adhesive coating layer 150 have a buffering effect on the stress exerted on the arc-shaped battery cell 10, thereby preventing the arc-shaped battery cell 10 from breaking or failing to shape during the bending process, thereby making the arc-shaped battery cell 10 easier to shape. Furthermore, the first hot melt adhesive coating layer 140 is bonded to one side of the diaphragm 130, the second hot melt adhesive coating layer 150 is bonded to the side of the diaphragm 130 away from the first hot melt adhesive coating layer 140, the positive electrode sheet 110 is bonded to the first hot melt adhesive coating layer 140, and the negative electrode sheet 120 is bonded to the second hot melt adhesive coating layer 150. When the arc-shaped battery cell 10 is subjected to a hot pressing operation, the first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 begin to melt and penetrate into the various bending parts of the arc-shaped battery cell 10, thereby repairing the wrinkles generated during the hot pressing process and making the surface of the arc-shaped battery cell 10 smoother. In addition, the first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 begin to melt during hot pressing, making the arc-shaped battery cell 10 easier to form and having better surface smoothness. After the arc-shaped battery cell 10 is formed, since the surface of the arc-shaped battery cell 10 returns to room temperature, the first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 are cooled and solidified again, so that the arc-shaped battery cell 10 maintains the curvature after forming and is not easy to rebound, thereby achieving a better shaping effect.

[0032] like Figure 3As shown, in one embodiment, the first hot melt adhesive coating layer 140 includes a first diaphragm coating portion 1420 and a first pole ear coating portion 1430, the first diaphragm coating portion 1420 is bonded to one side of the diaphragm 130, and the first pole ear coating portion 1430 is coated at the connection between the positive electrode sheet 110 and the positive electrode ear 200, that is, at least part of the positive electrode ear 200 and part of the positive electrode sheet 110 are coated inside the first pole ear coating portion 1430, and the first pole ear coating portion 1430 is connected to the first diaphragm coating portion 1420. It can be understood that the positive electrode ear 200 is connected to the positive electrode sheet 110, and when the arc-shaped lithium battery is hot-pressed, the arc direction of the positive electrode ear 200 is parallel to that of the positive electrode sheet 110, so the connection between the positive electrode ear 200 and the positive electrode sheet 110 is subject to certain stress, which can easily damage the connection between the positive electrode ear 200 and the positive electrode sheet 110. In order to improve the stability of the connection between the positive electrode tab 200 and the positive electrode sheet 110 during the hot pressing process, in this embodiment, the first hot melt adhesive coating layer 140 includes a first diaphragm coating portion 1420 and a first pole tab coating portion 1430. The first diaphragm coating portion 1420 is bonded to one side of the diaphragm 130, and the first pole tab coating portion 1430 is coated on the connection between the positive electrode sheet 110 and the positive electrode tab 200. The first pole tab coating portion 1430 is connected to the first diaphragm coating portion 1420. During the hot pressing process of the arc-shaped lithium battery, the first diaphragm coating portion 1420 can buffer the stress on the pole sheet and the diaphragm 130 in the arc-shaped battery cell 10, thereby making the arc-shaped battery cell 10 easier to shape. The first tab coating portion 1430 is coated on the connection between the positive electrode sheet 110 and the positive electrode tab 200. During the hot pressing operation, the first tab coating portion 1430 can reduce the stress on the connection between the positive electrode sheet 110 and the positive electrode tab 200, thereby improving the stability of the connection between the positive electrode tab 200 and the positive electrode sheet 110 during the hot pressing process. In addition, during the heat sealing process of the arc-shaped lithium battery, the first tab coating portion 1430 melts and has a repair and compensation effect on the packaging, making the bonding at the positive electrode tab 200 more firm and the sealing better.

[0033] like Figure 3As shown, in one embodiment, the second hot melt adhesive coating layer 150 includes a second diaphragm coating portion 1520 and a second pole ear coating portion 1530, the second diaphragm coating portion 1520 is bonded to the side of the diaphragm 130 away from the first hot melt adhesive coating layer 140, and the second pole ear coating portion 1530 is coated on the connection between the negative electrode sheet 120 and the negative electrode ear 300, that is, at least part of the negative electrode ear 300 and part of the negative electrode sheet 120 are coated inside the second pole ear coating portion 1530, and the second pole ear coating portion 1530 is connected to the second diaphragm coating portion 1520. It can be understood that the negative electrode ear 300 is connected to the negative electrode sheet 120, and when the arc-shaped lithium battery is hot-pressed, the arc direction of the negative electrode ear 300 is parallel to that of the negative electrode sheet 120, so the connection between the negative electrode ear 300 and the negative electrode sheet 120 is subjected to a certain stress, which is easy to damage the connection between the negative electrode ear 300 and the negative electrode sheet 120. In order to improve the stability of the connection between the negative electrode tab 300 and the negative electrode sheet 120 during the hot pressing process, in this embodiment, the second hot melt adhesive coating layer 150 includes a second diaphragm coating portion 1520 and a second electrode tab coating portion 1530. The second diaphragm coating portion 1520 is bonded to the side of the diaphragm 130 away from the first hot melt adhesive coating layer 140. The second electrode tab coating portion 1530 is coated on the connection between the negative electrode sheet 120 and the negative electrode tab 300. The second electrode tab coating portion 1530 is connected to the second diaphragm coating portion 1520. During the hot pressing process of the arc-shaped lithium battery, the second diaphragm coating portion 1520 can buffer the stress on the electrode sheet and the diaphragm 130 in the arc-shaped battery cell 10, thereby making the arc-shaped battery cell 10 easier to shape. The second tab coating portion 1530 is coated on the connection between the negative electrode sheet 120 and the negative electrode tab 300. During the hot pressing operation, the second tab coating portion 1530 can reduce the stress on the connection between the negative electrode sheet 120 and the negative electrode tab 300, thereby improving the stability of the connection between the negative electrode tab 300 and the negative electrode sheet 120 during the hot pressing process. In addition, during the heat sealing process of the arc-shaped lithium battery, the second tab coating portion 1530 melts and has a repair and compensation effect on the packaging, making the bonding at the negative electrode tab 300 more firm and the sealing better.

[0034] In one of the embodiments, the thickness of the middle part of the first hot melt adhesive coating layer 140 is greater than the thickness of the two sides of the first hot melt adhesive coating layer 140. It is understandable that when the arc-shaped lithium battery is subjected to hot pressing, that is, when the lithium battery to be formed is subjected to a bending operation, the stress on the middle part of the lithium battery to be formed is greater than the stress on its two sides, thereby making the bending part of the arc-shaped lithium battery more fragile and the overall structural stability is poor. In order to further improve the structural stability of the arc-shaped lithium battery and the repair and compensation effect on the bent part of the arc-shaped lithium battery, in this embodiment, the thickness of the middle part of the first hot melt adhesive coating layer 140 is greater than the thickness of the two sides of the first hot melt adhesive coating layer 140, and the middle part of the first hot melt adhesive coating layer 140 corresponds to the bent part of the arc-shaped lithium battery, so that during the bending forming process of the lithium battery to be formed, the bent part can obtain a better repair and compensation effect, and the structural stability of the arc-shaped lithium battery is higher.

[0035] In one of the embodiments, the thickness of the middle part of the second hot melt adhesive coating layer 150 is greater than the thickness of the two sides of the second hot melt adhesive coating layer 150. It can be understood that when the arc-shaped lithium battery is subjected to hot pressing, that is, when the lithium battery to be formed is subjected to a bending operation, the stress on the middle part of the lithium battery to be formed is greater than the stress on its two sides, thereby making the bending part of the arc-shaped lithium battery more fragile and the overall structural stability is poor. In order to further improve the structural stability of the arc-shaped lithium battery and the repair and compensation effect on the bent part of the arc-shaped lithium battery, in this embodiment, the thickness of the middle part of the second hot melt adhesive coating layer 150 is greater than the thickness of the two sides of the second hot melt adhesive coating layer 150, and the middle part of the second hot melt adhesive coating layer 150 corresponds to the bent part of the arc-shaped lithium battery, so that during the bending forming process of the lithium battery to be formed, the bent part can obtain a better repair and compensation effect, and the structural stability of the arc-shaped lithium battery is higher.

[0036] In one embodiment, the positive electrode sheet 110 includes a positive electrode current collector, and a plurality of first pores are provided on the positive electrode current collector. It is understandable that the function of the current collector is mainly to collect the current generated by the active material of the battery so as to form a larger current for external output. In order to make the positive electrode current collector more fully contact with the active material and effectively reduce the internal resistance. In this embodiment, the positive electrode current collector is an aluminum foil, and a plurality of first pores are provided on the aluminum foil, so that the positive electrode current collector is more fully in contact with the active material and effectively reduce the internal resistance. Compared with traditional smooth foil materials, the volume energy density of the positive electrode current collector in this embodiment can be increased by more than 5%. At the same time, the first pores on the aluminum foil can release the bending stress of the electrode, improve the flexibility of the electrode coating, and reduce the difficulty of the arc forming process of the lithium battery.

[0037] Furthermore, the aperture of the first pore is 0.1mm to 0.4mm. It is understandable that if the aperture of the first pore is large, it is easy to affect the current collecting effect of the positive current collector and the flexibility of the positive current collector; if the aperture of the first pore is small, the positive current collector is not in sufficient contact with the active material, and the internal resistance is large. In order to further improve the current collecting effect of the positive current collector and effectively reduce the internal resistance, in this embodiment, the aperture of the first pore is 0.2mm, so that the positive current collector is in more sufficient contact with the active material, and the internal resistance is effectively reduced, while also being able to effectively ensure the current collecting effect of the positive current collector and the flexibility of the positive current collector.

[0038] In one embodiment, the negative electrode sheet 120 includes a negative electrode current collector, and a plurality of second pores are provided on the negative electrode current collector. It is understandable that the function of the current collector is mainly to collect the current generated by the active material of the battery so as to form a larger current for external output. In order to make the negative electrode current collector contact with the active material more fully and effectively reduce the internal resistance. In this embodiment, the negative electrode current collector is a copper foil, and a plurality of second pores are provided on the copper foil, so that the negative electrode current collector is in contact with the active material more fully and effectively reduces the internal resistance. Compared with traditional smooth foil materials, the volume energy density of the negative electrode current collector in this embodiment can be increased by more than 5%. At the same time, the second pores on the aluminum foil can release the bending stress of the electrode, improve the flexibility of the electrode coating, and reduce the difficulty of the arc forming process of the lithium battery.

[0039] Furthermore, the aperture of the second pore is 0.1 mm to 0.4 mm. It is understandable that if the aperture of the second pore is large, it is easy to affect the current collecting effect of the negative electrode collector and the flexibility of the negative electrode collector; if the aperture of the second pore is small, the negative electrode collector is not in sufficient contact with the active material, and the internal resistance is large. In order to further improve the current collecting effect of the negative electrode collector and effectively reduce the internal resistance, in this embodiment, the aperture of the second pore is 0.2 mm, so that the negative electrode collector is in more sufficient contact with the active material, and the internal resistance is effectively reduced, while also being able to effectively ensure the current collecting effect of the negative electrode collector and the flexibility of the negative electrode collector.

[0040] In one embodiment, the sum of the thickness of the first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 is less than the thickness of the diaphragm 130. It is understood that the diaphragm 130 is a thin film used to separate the positive and negative electrodes to prevent the loss of energy in the electrolytic cell by direct reaction. In the structure of the lithium battery, the diaphragm 130 is one of the key inner layer components. The performance of the diaphragm 130 determines the interface structure and internal resistance of the battery, and directly affects the battery's capacity, cycle and safety performance. The thickness of the diaphragm 130 will also affect the internal resistance of the diaphragm 130 in the lithium battery structure. The first hot melt adhesive coating layer 140 is bonded to one side of the diaphragm 130, the second hot melt adhesive coating layer 150 is bonded to the side of the diaphragm 130 away from the first hot melt adhesive coating layer 140, the positive electrode sheet 110 is bonded to the first hot melt adhesive coating layer 140, and the negative electrode sheet 120 is bonded to the second hot melt adhesive coating layer 150. That is to say, the first hot melt adhesive coating layer 140, the diaphragm 130 and the second hot melt adhesive coating layer 150 form a new diaphragm. The thickness of the new diaphragm is relatively large, which easily causes a large internal resistance of the diaphragm, and ultimately affects the electrical performance of the arc-shaped lithium battery. In order to reduce the internal resistance of the new diaphragm composed of the first hot melt adhesive coating layer 140, the diaphragm 130 and the second hot melt adhesive coating layer 150, in this embodiment, the sum of the thickness of the first hot melt adhesive coating layer 140 and the second hot melt adhesive coating layer 150 is less than the thickness of the diaphragm 130. On the one hand, it can effectively improve the flexibility and adhesion of the diaphragm 130, making the arc-shaped lithium battery easier to form; on the other hand, it can make the internal resistance of the new diaphragm smaller, thereby ensuring the electrical performance of the arc-shaped lithium battery.

[0041] In one embodiment, the bending direction of the positive electrode sheet 110 and the negative electrode sheet 120 is consistent with the bending direction of the battery body 100. In this embodiment, the battery body 100 is formed by a hot pressing molding integrated process, so that the bending direction of the positive electrode sheet 110 and the negative electrode sheet 120 is consistent with the bending direction of the battery body 100, thereby increasing the flexibility of the battery after molding, facilitating the bending molding of the lithium battery, and the winding direction is parallel to the arc molding direction, preventing the internal structure of the battery from being damaged due to uniform internal force when the battery is arc-shaped, and preventing problems such as short circuit or open circuit of the electrode sheet.

[0042] In one of the embodiments, the diaphragm is provided with a first groove and a second groove, the first hot melt adhesive coating layer is provided with a first protrusion, the first protrusion is embedded in the first groove, and the second hot melt adhesive coating layer is provided with a second protrusion, the second protrusion is embedded in the second groove. In this embodiment, the first protrusion is embedded in the first groove, and the second protrusion is embedded in the second groove, so that the diaphragm is more tightly bonded to the first hot melt adhesive coating layer and the second hot melt adhesive coating layer, effectively preventing the diaphragm from sliding relative to the first hot melt adhesive coating layer and the second hot melt adhesive coating layer, thereby making the battery body in the arc-shaped battery cell more stable.

[0043] The present application also provides a curved lithium battery 20 , which includes the curved battery cell 10 as described in any of the above embodiments, and also includes a curved aluminum-plastic film 700 , wherein the curved aluminum-plastic film 700 is coated on the outer surface of the curved battery cell 10 .

[0044] In one embodiment, the arc-shaped lithium battery adopts an integrated hot pressing forming process, which specifically includes the following steps: making a positive electrode sheet, a negative electrode sheet and a separator; performing a hot melt adhesive coating operation on the surface of the separator to obtain a separator with a hot melt adhesive coating layer; performing a winding operation on the positive electrode sheet, the negative electrode sheet and the separator with a hot melt adhesive coating layer; after completing the winding operation, welding the positive electrode tab to the positive electrode sheet, and welding the negative electrode tab to the negative electrode sheet to obtain a lithium battery cell; placing the lithium battery cell into an aluminum-plastic sleeve to obtain a lithium battery to be formed; performing a hot pressing forming operation on the lithium battery to be formed to obtain a arc-shaped lithium battery to be packaged; performing a packaging operation on the arc-shaped lithium battery to be packaged to obtain the arc-shaped lithium battery.

[0045] In the above-mentioned arc-shaped lithium battery hot-pressing integrated process, a hot-melt adhesive coating operation is performed on the surface of the diaphragm to form a hot-melt adhesive coating layer on the surface of the diaphragm. The hot-melt adhesive has good bonding properties, so that the bonding between the diaphragm and the positive and negative pole pieces is tighter and stronger. In this way, after the positive pole piece, the negative pole piece and the diaphragm with the hot-melt adhesive coating layer are wound, the structure of the lithium battery cell can be made more stable. Further, after the winding operation is completed, the positive pole ear is welded to the positive pole piece, and the negative pole ear is welded to the negative pole piece to obtain a lithium battery cell. Then the lithium battery cell is placed in an aluminum-plastic sleeve to obtain a lithium battery to be formed, and the lithium battery to be formed is subjected to a hot-pressing integrated operation. On the one hand, the lithium battery cell and the aluminum-plastic sleeve can be integrated through hot-pressing integration, and on the other hand, the lithium battery to be formed can be bent to a preset curvature arc-shaped lithium battery. Compared with the traditional method for making an arc-shaped lithium battery, the present invention can achieve hot-pressing integration, thereby simplifying the production process of the arc-shaped lithium battery and improving the production efficiency. In addition, after the integrated hot pressing operation is completed, the surface temperature of the arc-shaped lithium battery drops, and the hot melt adhesive coated on the surface of the diaphragm solidifies and forms again, so that the curvature of the arc-shaped lithium battery solidifies and remains stable, and rebound is not likely to occur. Furthermore, in the hot pressing process of the present application, the hot melt adhesive coated on the diaphragm melts again, and the melted hot melt adhesive can flow in the aluminum-plastic sleeve, thereby compensating for the gap between the aluminum-plastic and the diaphragm when the lithium battery is arc-formed, and then effectively repairing the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bend of the arc-shaped lithium battery, so that the surface of the arc-shaped lithium battery is smoother, which is conducive to improving the performance of the arc-shaped lithium battery.

[0046] In order to better understand the integrated hot-pressing forming process of the arc-shaped lithium battery of the present invention, the integrated hot-pressing forming process of the arc-shaped lithium battery of the present invention is further explained as follows:

[0047] like Figure 1 As shown, a hot pressing and forming integrated process for a curved lithium battery in one embodiment includes some or all of the following steps:

[0048] S100, manufacturing positive electrode sheets, negative electrode sheets and separators.

[0049] In this embodiment, the production process of the positive electrode plate is as follows: prepare a positive electrode inner layer slurry and a positive electrode outer layer slurry, the positive electrode inner layer slurry includes a positive electrode inner layer active material, the positive electrode outer layer slurry includes a positive electrode outer layer active material, and the stability of the positive electrode inner layer active material is better than the stability of the positive electrode outer layer active material; wherein, the positive electrode inner layer active material includes one or more of lithium iron phosphate, lithium cobalt oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum high nickel material and lithium titanate, and the positive electrode outer layer active material includes one or more of lithium iron phosphate, lithium cobalt oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum high nickel material and lithium titanate; apply the positive electrode inner layer slurry and the positive electrode outer layer slurry to the battery positive electrode carrier to obtain a lithium battery positive electrode plate. The preparation process of the negative electrode plate is as follows: prepare the negative electrode inner layer slurry and the negative electrode outer layer slurry, wherein the negative electrode inner layer slurry includes the negative electrode inner layer active material, the negative electrode outer layer slurry includes the negative electrode outer layer active material, and the stability of the negative electrode inner layer active material is better than the stability of the negative electrode outer layer active material; wherein the negative electrode inner layer active material includes one or more of natural graphite, artificial graphite, a composite material of natural graphite and artificial graphite, soft carbon, hard carbon, and lithium titanate, and the negative electrode outer layer active material includes one or more of natural graphite, artificial graphite, a composite material of natural graphite and artificial graphite, soft carbon, hard carbon, and lithium titanate; and apply the negative electrode inner layer slurry and the negative electrode outer layer slurry to the battery negative electrode carrier to obtain the lithium battery negative electrode plate. The diaphragm in this embodiment is prepared by a dry diaphragm preparation process.

[0050] S200, performing a hot melt adhesive coating operation on the surface of the diaphragm to obtain a diaphragm having a hot melt adhesive coating layer.

[0051] In this embodiment, a coating device is used to coat the hot melt adhesive on the surfaces of both sides of the diaphragm, so that the hot melt adhesive is coated on the diaphragm to form a diaphragm with a hot melt adhesive coating layer. Since the hot melt adhesive has good bonding properties, the bonding between the diaphragm and the positive and negative electrode sheets is tighter and stronger. In this way, after the positive electrode sheet, the negative electrode sheet and the diaphragm with the hot melt adhesive coating layer are wound, the structure of the lithium battery cell can be made more stable.

[0052] S300, winding the positive electrode sheet, the negative electrode sheet and the separator with the hot melt adhesive coating layer.

[0053] In this embodiment, the positive electrode sheet, the negative electrode sheet and the separator with the hot melt adhesive coating layer are wound, wherein the separator with the hot melt adhesive coating layer is located between the positive electrode sheet and the negative electrode sheet. Furthermore, the steps of winding the positive electrode sheet, the negative electrode sheet and the diaphragm with a hot-melt adhesive coating layer are specifically as follows: using an arc-shaped tape measure to vertically wind the positive electrode sheet, the negative electrode sheet and the diaphragm with a hot-melt adhesive coating layer, the arc-shaped tape measure includes a fixing portion connected to a winding device and a winding portion for fixing the positive electrode sheet, the negative electrode sheet and the diaphragm, a long strip notch is provided in the middle of the winding portion to divide the winding portion into two symmetrical halves, one side of the winding portion is a plane, and the other side is an arc-shaped surface, and the calculation of the arc-shaped surface is: the width of the arc-shaped tape measure F=B-D, and the arc length of the arc-shaped tape measure H=F-E; wherein, the inner arc length of the arc battery is B, the number of winding layers of the arc battery is C, the thickness of the arc battery is D, and the radius of the central angle of the arc battery is R. First, the thickness D of the arc battery is divided into N equal parts, N=(C-2), and the difference in arc length of each equal part is E.

[0054] S400, after the winding operation is completed, the positive electrode tab is welded to the positive electrode sheet, and the negative electrode tab is welded to the negative electrode sheet to obtain a lithium battery cell.

[0055] In this embodiment, after the winding operation is completed, a 3mm to 5mm empty foil position is reserved for the tab spot welding, and then the tab welding device is used to weld the positive tab to the welding point of the positive tab, and the negative tab to the welding point of the negative tab, thereby obtaining a lithium battery cell.

[0056] S500, placing the lithium battery cell into the aluminum-plastic sleeve to obtain a lithium battery to be formed.

[0057] In this embodiment, the lithium battery cell is placed in an aluminum-plastic sleeve for pre-packaging. Specifically, the aluminum-plastic sleeve includes an upper shell and a lower shell. The upper shell and the lower shell are punched out with a groove corresponding to the shape of the lithium battery cell using a punching die, and one end of the upper shell is connected to the lower shell as a whole. The lithium battery cell is placed in the groove of the lower shell, and then the upper shell is folded to match the lower shell. The packaging head is used to press the edges of the upper shell and the lower shell, so that the aluminum-plastic film presses the lithium battery cell, and the lithium battery to be formed is obtained, so that the lithium battery to be formed can be hot-pressed and formed as a whole later.

[0058] S600, performing a hot pressing operation on the lithium battery to be formed to obtain a curved lithium battery to be packaged.

[0059] It is understandable that the positive electrode tab is welded to the positive electrode sheet, and the negative electrode tab is welded to the negative electrode sheet to obtain a lithium battery cell. The lithium battery cell is then placed in an aluminum-plastic sleeve to obtain a lithium battery to be formed, which is conducive to hot pressing. In this embodiment, the lithium battery to be formed is subjected to an integrated hot pressing operation. On the one hand, the lithium battery cell and the aluminum-plastic sleeve can be integrated through the hot pressing integration, and on the other hand, the lithium battery to be formed can be bent into an arc-shaped lithium battery with a preset curvature. Compared with the traditional method for making arc-shaped lithium batteries, this embodiment can achieve hot pressing integration, thereby simplifying the production process of arc-shaped lithium batteries and improving production efficiency. In addition, after completing the hot pressing integration operation, the surface temperature of the arc-shaped lithium battery drops, and the hot melt adhesive coated on the surface of the diaphragm is solidified and formed again, so that the curvature of the arc-shaped lithium battery is solidified and remains stable, and rebound is not easy to occur. In addition, during the hot pressing process, the hot melt adhesive coated on the diaphragm melts again, and the melted hot melt adhesive can flow in the aluminum-plastic sleeve, thereby compensating for the gap between the aluminum-plastic and the diaphragm when the lithium battery is arc-formed. It can effectively repair the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bending part, making the surface of the arc-shaped lithium battery smoother, which is beneficial to improving the performance of the arc-shaped lithium battery.

[0060] S700, performing a packaging operation on the arc-shaped lithium battery to be packaged to obtain an arc-shaped lithium battery.

[0061] It can be understood that after the lithium battery to be formed undergoes the integrated operation of hot pressing and forming, a curved lithium battery to be packaged with a certain curvature is obtained. In order to improve the protective effect of the aluminum-plastic film on the curved lithium battery cell, in this embodiment, the curved lithium battery to be packaged is packaged, thereby effectively improving the packaging effect of the aluminum-plastic film on the curved lithium battery cell, improving the protective effect of the aluminum-plastic film on the curved lithium battery cell, and improving the safety and life of the curved lithium battery.

[0062] In one embodiment, the melting point of the hot melt adhesive is less than the melting point of the diaphragm. It is understandable that the hot melt adhesive is applied to the surface of the diaphragm to form a hot melt adhesive coating layer on the surface of the diaphragm. When the lithium battery to be formed is undergoing a hot pressing operation, the hot melt adhesive applied to the surface of the diaphragm gradually reaches the melting point and begins to melt. The melted hot melt adhesive can flow in the aluminum-plastic sleeve, thereby compensating for the gap between the aluminum-plastic and the diaphragm when the lithium battery is arc-formed, and can effectively repair the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bend of the arc-shaped lithium battery, so that the surface of the arc-shaped lithium battery is smoother, which is beneficial to improving the performance of the arc-shaped lithium battery. However, if the melting point of the hot melt adhesive is too high, it is difficult to melt during the hot pressing process, and the compensation and repair effect on the surface of the arc-shaped lithium battery cannot be achieved. In addition, the melting point of the hot melt adhesive is relatively high, and it is easy to damage the diaphragm during the melting process. In this embodiment, the melting point of the hot melt adhesive is lower than the melting point of the diaphragm, so that the hot melt adhesive is easier to melt during the hot pressing process, and during the melting process, the diaphragm will not be damaged due to overheating, and the diaphragm is protective.

[0063] Furthermore, the melting point of the hot melt adhesive is 100°C to 120°C. In this embodiment, the melting point of the lithium battery separator is 160°C, and the melting point of the hot melt adhesive is lower than the melting point of the separator. When the lithium battery to be formed is subjected to hot pressing forming operation, the hot melt adhesive can reach a better melting state, so that the hot melt adhesive has better fluidity and can flow better to the corners and gaps inside the lithium battery. During the hot pressing forming process, it has a better compensation and repair effect on the surface of the arc-shaped lithium battery, prevents the appearance of wrinkles, and makes the surface of the arc-shaped lithium battery smoother. At the same time, during the melting process, the hot melt adhesive will not damage the separator due to overheating, further improving the protection of the separator.

[0064] In one embodiment, the temperature during the hot pressing operation is 130°C to 150°C. In this embodiment, the temperature of the hot pressing of the lithium battery to be formed is greater than the melting point of the hot melt adhesive and less than the melting point of the lithium battery separator, so that the hot melt adhesive coated on the surface of the separator can be fully melted without damaging the lithium battery separator, so that the hot melt adhesive can better compensate and repair the surface of the curved lithium battery, while ensuring the performance of the curved lithium battery.

[0065] Furthermore, the pressure in the hot pressing operation is 0.4MPa to 0.8MPa. It is understandable that in the hot pressing operation, the hot pressing integration of the arc lithium battery is achieved by applying a certain temperature and pressure to the lithium battery to be formed. However, if the pressure in the hot pressing process is too large, it is easy to damage the arc lithium battery; if the pressure in the hot pressing process is too small, it is easy to fail to bend the arc lithium battery to a predetermined curvature. In this embodiment, in the hot pressing operation, a hot pressing head is used to apply a pressure of 0.6MPa to the lithium battery to be formed, and the temperature of the hot pressing head is 140°C, so that the hot melt adhesive is in a molten state during the hot pressing process. On the one hand, it can better compensate and repair the surface of the arc lithium battery during the hot pressing process, so that the arc lithium battery reaches a predetermined curvature and has a better surface flatness; on the other hand, through the combination of pressure and temperature, the forming effect of the arc lithium battery is better.

[0066] Furthermore, the hot pressing time in the hot pressing forming operation is 4 seconds to 7 seconds. In this embodiment, by controlling the hot pressing time in the hot pressing forming operation to 5 seconds, the temperature is 140° C., and the pressure is 0.6 MPa, the arc-shaped lithium battery obtained in the hot pressing forming operation has a higher forming rate and a better forming effect.

[0067] In one embodiment, after the steps of making the positive electrode sheet, the negative electrode sheet and the diaphragm, the hot melt adhesive coating operation is performed on the surface of the diaphragm, and before the step of obtaining the diaphragm with the hot melt adhesive coating layer, the following steps are also included: heating the hot melt adhesive. It can be understood that by applying the hot melt adhesive to the surface of the diaphragm, it is beneficial to the shaping of the arc-shaped lithium battery after hot pressing, and it has a good compensation and repair effect on the surface of the arc-shaped lithium battery during the hot pressing process, thereby improving the flatness of the surface of the arc-shaped lithium battery. However, the hot melt adhesive is prone to coating difficulties and poor coating uniformity during the coating process of the diaphragm. In order to improve the coating uniformity of the hot melt adhesive on the diaphragm and make the coating more convenient, in this embodiment, after the steps of making the positive electrode sheet, the negative electrode sheet and the diaphragm, the hot melt adhesive coating operation is performed on the surface of the diaphragm, and before the step of obtaining the diaphragm with the hot melt adhesive coating layer, the hot melt adhesive is heated to make the hot melt adhesive in a semi-molten state, so that the hot melt adhesive is easier to apply, and it is not easy to fall off after being applied to the diaphragm, and the coating uniformity on the diaphragm is better.

[0068] In one embodiment, the hot melt adhesive includes at least one of polyamide, polyester, polyethylene and polyesteramide. It is understandable that the hot melt adhesive is applied to the surface of the diaphragm. During the hot pressing process, the hot melt adhesive applied to the diaphragm melts again, and the melted hot melt adhesive can flow in the aluminum-plastic sleeve, thereby compensating for the gap between the aluminum-plastic and the diaphragm when the lithium battery is arc-formed, and then effectively repairing the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bend of the arc-shaped lithium battery, so that the surface of the arc-shaped lithium battery is smoother. After completing the integrated hot pressing operation, the surface temperature of the arc-shaped lithium battery drops, and the hot melt adhesive applied to the surface of the diaphragm solidifies and forms again, so that the arc of the arc-shaped lithium battery solidifies and remains stable, and rebound is not easy to occur. However, some hot melt adhesives cannot cooperate well with the hot pressing conditions of the arc-shaped lithium battery, and have a high melting point and poor hardness after cooling, thereby affecting the shaping effect and stability of the arc-shaped lithium battery. In order to improve the shaping effect and stability of the arc-shaped lithium battery, in this embodiment, the hot melt adhesive includes at least one of polyamide, polyester, polyethylene and polyester amide, and the melting points of polyamide, polyester, polyethylene and polyester amide are all 105°C to 115°C, which is lower than the melting point of the diaphragm. After the hot pressing molding operation is completed, the surface of the arc-shaped lithium battery returns to room temperature, and the room temperature is much lower than the melting point of polyamide, polyester, polyethylene and polyester amide, so that the arc of the arc-shaped lithium battery is solidified and remains stable, and rebound is not likely to occur. In addition, the hardness of polyamide, polyester, polyethylene and polyester amide is relatively high, and the cooled polyamide, polyester, polyethylene and polyester amide are conducive to improving the shaping effect and stability of the arc-shaped lithium battery.

[0069] Furthermore, polyamide has light weight, excellent wrinkle resistance, good durability, corrosion resistance and heat setting. When polyamide is coated on the diaphragm, it is beneficial to improve the hot pressing setting effect of the arc lithium battery, and the surface of the hot melt adhesive has good wrinkle resistance after hot pressing, which is beneficial to improve the structural stability and electrical performance of the arc lithium battery. Polyester is a general term for polymers obtained by polycondensation of polyols and polyacids. In this embodiment, polyester mainly refers to polyethylene terephthalate. The crystallization rate of polyethylene terephthalate melt is fast when cooling, which is beneficial to improve the accuracy and setting efficiency of the arc of the arc lithium battery. At the same time, polyethylene terephthalate is light in weight, has high mechanical strength, is not easy to break after molding, and has high stability. Polyethylene is a thermoplastic resin obtained by polymerization of polyethylene. Polyethylene has good chemical stability, can withstand the erosion of most acids and alkalis, has good corrosion resistance to the electrolyte of the arc lithium battery, and polyethylene has good electrical insulation, which is beneficial to improve the insulation effect of the diaphragm.

[0070] In one of the embodiments, after placing the lithium battery cell into an aluminum-plastic sleeve to obtain the lithium battery to be formed, before performing a hot pressing forming operation on the lithium battery to be formed to obtain the arc-shaped lithium battery to be packaged, the following steps are also included: preheating the lithium battery to be formed. It can be understood that after completing the winding operation, the present application welds the positive electrode tab to the positive electrode sheet and welds the negative electrode tab to the negative electrode sheet to obtain the lithium battery cell. Then the lithium battery cell is placed in an aluminum-plastic sleeve to obtain the lithium battery to be formed, and the lithium battery to be formed is subjected to a hot pressing forming integration operation. On the one hand, the lithium battery cell and the aluminum-plastic sleeve can be integrated through hot pressing forming integration, and on the other hand, the lithium battery to be formed can be bent into an arc-shaped lithium battery with a preset curvature. However, during the hot pressing forming process, due to the presence of an aluminum-plastic film between the hot melt adhesive and the hot pressing head, the heat conduction speed of the hot melt adhesive is slow, and the hot melt adhesive is heated unevenly, thereby affecting the hot pressing forming of the arc-shaped lithium battery. In this embodiment, after the step of placing the lithium battery cell into the aluminum-plastic sleeve to obtain the lithium battery to be formed, and before the step of performing hot pressing molding on the lithium battery to be formed to obtain the arc-shaped lithium battery to be packaged, the following steps are also included: preheating the lithium battery to be formed, so that the hot melt adhesive coating on the surface of the diaphragm is pre-molten by the preheating operation, and then performing the hot pressing molding operation, thereby increasing the thermal conductivity of the hot melt adhesive during hot pressing, making the hot melt adhesive heated more evenly, which is beneficial to the hot pressing molding of the arc-shaped lithium battery, and at the same time allowing the hot melt adhesive to extend more comprehensively to all corners of the lithium battery, thereby more effectively repairing the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bend of the arc-shaped lithium battery, so that the surface of the arc-shaped lithium battery is smoother, which is beneficial to improving the performance of the arc-shaped lithium battery.

[0071] Furthermore, the preheating temperature in the preheating operation is 100°C to 120°C. It is understandable that the preheating operation allows the hot melt adhesive coating on the surface of the diaphragm to reach a semi-molten state in advance, and then the hot pressing operation is performed, thereby increasing the heat conduction rate of the hot melt adhesive during hot pressing, making the hot melt adhesive more evenly heated, which is beneficial to the hot pressing of the arc-shaped lithium battery. In order to make the hot melt adhesive layer reach a more uniform and stable molten state, and at the same time prevent damage to the diaphragm during the preheating process, in this embodiment, the preheating temperature in the preheating operation is 130°C. At this temperature, the hot melt adhesive is close to the melting point, so that the hot melt adhesive layer reaches a more uniform and stable molten state, so that the hot melt adhesive can extend more comprehensively to every corner inside the lithium battery, and then can more effectively repair the wrinkles generated on the surface of the arc-shaped lithium battery during the hot pressing process, especially at the bend of the arc-shaped lithium battery, so that the surface of the arc-shaped lithium battery is smoother, which is beneficial to improving the performance of the arc-shaped lithium battery. Furthermore, the melting point of the diaphragm is 160°C, and the melting point of the hot melt adhesive is lower than that of the diaphragm, which can effectively prevent damage to the diaphragm during the preheating process and further improve the safety of the arc-shaped lithium battery.

[0072] Furthermore, the preheating operation is specifically to blow hot air inside the aluminum-plastic sleeve. It is understandable that before the hot pressing and forming integration operation is performed, the lithium battery cell is placed in the aluminum-plastic sleeve, including a diaphragm coated with a hot melt adhesive layer. In this embodiment, a blower is used to blow hot air inside the aluminum-plastic sleeve of the lithium battery to be formed, which solves the problems of slow and uneven heat conduction caused by the heat insulation effect of the aluminum-plastic sleeve, so that the hot melt adhesive reaches a semi-molten state to a molten state before the hot pressing and forming integration operation, and then the hot pressing and forming operation is performed, thereby increasing the heat conduction speed of the hot melt adhesive during hot pressing, making the hot melt adhesive more evenly heated, which is beneficial to the hot pressing and forming of the arc lithium battery, and at the same time, the hot melt adhesive can be more fully extended to all corners inside the lithium battery, and then can more effectively repair the wrinkles generated on the surface of the arc lithium battery during the hot pressing process, especially at the bend of the arc lithium battery, so that the surface of the arc lithium battery is smoother, which is beneficial to improving the performance of the arc lithium battery. At the same time, the hot melt adhesive can penetrate into the ear, thereby improving the electrical performance of the arc-shaped lithium battery and facilitating the sealing of the arc-shaped lithium battery during subsequent packaging.

[0073] In one of the embodiments, the air supply direction in the hot air blowing operation rotates 360 degrees relative to the opening of the aluminum-plastic sleeve. It is understandable that before the hot-pressing integrated operation of the lithium battery to be formed is performed, the blower is used to blow hot air into the aluminum-plastic sleeve of the lithium battery to be formed, which can solve the problem of slow heat conduction and uneven heat conduction caused by the heat insulation effect of the aluminum-plastic sleeve, so that the hot melt adhesive reaches a semi-molten state to a molten state before the hot-pressing integrated operation. However, in the process of blowing hot air, due to the excessive concentration of the air supply direction, it is easy for the hot air to heat the hot melt adhesive unevenly, thereby affecting the melting state of the hot melt adhesive and easily affecting the preheating rate. In this embodiment, by controlling and adjusting the air outlet of the blower, the air supply direction in the hot air blowing operation rotates 360 degrees relative to the opening of the aluminum-plastic sleeve, so that the hot air is evenly blown to the hot melt adhesive in the aluminum-plastic sleeve through the opening of the aluminum-plastic sleeve, so that the hot air heats the hot melt adhesive more evenly, and then the hot melt adhesive reaches a semi-molten state to a molten state faster, which is more conducive to the hot pressing effect of the arc lithium battery.

[0074] Furthermore, the rotation rate of the hot air in the air supply direction is 12 rpm to 20 rpm. In this embodiment, when the hot air blowing operation is performed, the air outlet of the air supply device is controlled and adjusted to make the rotation rate of the hot air in the air supply direction 12 rpm to 20 rpm, so that the hot air heats the hot melt adhesive more evenly, and the hot melt adhesive reaches a semi-molten state to a molten state more quickly, which is more conducive to the hot pressing effect of the arc lithium battery. At the same time, it is avoided that the hot air is blown for too long at one air supply angle, causing the problem of local overheating in the aluminum-plastic sleeve, thereby improving the safety of the preheating operation.

[0075] In one embodiment, the direction of the positive electrode tab and the negative electrode tab is consistent with the winding direction. In this embodiment, the tab welding direction is parallel to the electrode sheet, which increases the flexibility of the lithium battery after formation, facilitates the bending and shaping of the battery, and the direction of the positive electrode tab and the negative electrode tab is consistent with the winding direction, and the winding direction is parallel to the arc forming direction, which prevents the internal structure of the battery cell from being damaged due to uniform internal force when the battery cell is arc-shaped, and prevents problems such as short circuit or open circuit of the electrode sheet.

[0076] In one embodiment, the packaging operation specifically includes the following steps:

[0077] S710, encapsulate the top edge of the aluminum-plastic sleeve. Encapsulate the three sides of the aluminum-plastic sleeve in the following order: encapsulate the top edge first, then the bottom edge, and reserve one side as the liquid injection port.

[0078] In this embodiment, a lithium battery packaging device is used to perform a top sealing operation from the top edge, thereby completing partial packaging of the arc-shaped lithium battery, which is also beneficial to the subsequent side sealing operation, and the bottom edge and the side edge are packaged in sequence, so that the packaging sealing of the aluminum-plastic sleeve is better, and one side is reserved as a liquid injection port, which is convenient for the subsequent injection of electrolyte into the arc-shaped lithium battery to be packaged.

[0079] S720, respectively encapsulating both sides of the aluminum-plastic sleeve, and reserving a liquid injection port on one side of the aluminum-plastic sleeve to sequentially perform liquid injection, formation and degassing operations on the arc-shaped lithium battery to be encapsulated through the liquid injection port.

[0080] In this embodiment, a packaging head is used to package the two sides of the aluminum-plastic sleeve respectively, so as to further package the arc-shaped lithium battery, so that the sealing performance of the aluminum-plastic sleeve is better, and one side is reserved as a liquid injection port, which is convenient for injecting electrolyte into the arc-shaped lithium battery to be packaged. A liquid injection machine is used to perform liquid injection operation from the liquid injection port. After the liquid injection is completed, a formation device is used to perform a formation operation on the lithium battery to be packaged, and then a degassing operation is performed, which is conducive to the subsequent sealing operation and prevents the gas generated inside the lithium battery from adversely affecting the performance of the lithium battery.

[0081] S730, performing a liquid injection operation, a formation operation, and a degassing operation on the arc-shaped lithium battery to be packaged in sequence through the liquid injection port.

[0082] In this embodiment, a liquid injection machine is used to perform liquid injection operation from the liquid injection port. After the liquid injection is completed, a formation device is used to perform a formation operation on the packaged lithium battery, and then a degassing operation is performed, which is beneficial to the subsequent sealing operation and prevents the gas generated inside the lithium battery from adversely affecting the performance of the lithium battery.

[0083] S740, after the degassing operation is completed, the liquid injection port is sealed.

[0084] In this embodiment, after the lithium battery to be packaged is degassed, all the air inside the lithium battery to be packaged is exhausted, so that the inside of the lithium battery to be packaged is kept in vacuum, and then the injection port is sealed, so that the sealing of the lithium battery packaging can be effectively improved, thereby improving the electrical performance of the lithium battery. Further, after the reserved injection port is sealed, the reserved edge is folded, and finally the edge of the arc-shaped aluminum-plastic film 5 forms a first folded edge, a second folded edge connected to the first folded edge, and a third folded edge connected to the second folded edge, and the outer packaging is packaged by a single-sided packaging method in the side sealing direction, which can save 0.5mm of space in the battery width direction and improve the volume energy density of the battery.

[0085] In one of the embodiments, the step of applying hot melt adhesive on the surface of the diaphragm is specifically as follows: spraying the hot melt adhesive on the surface of the diaphragm. The hot melt adhesive application operation adopts a spraying method. It is understandable that the hot melt adhesive is applied to the surface of the diaphragm, and after hot pressing and integration, the hot melt adhesive melts and penetrates into the pole ear, so that it is not easy to rebound after pressing, and the wrinkles in the hot pressing process can be repaired. However, the corners of the diaphragm are difficult to coat, and the problem of missing coating is prone to occur, thereby affecting the compensation and repair effect of the hot melt adhesive on the arc lithium battery. In this embodiment, the hot melt adhesive coating operation adopts a spraying method, which can apply the hot melt adhesive more comprehensively to the diaphragm to prevent the phenomenon of missing coating on the corners of the diaphragm. Furthermore, after the hot melt adhesive is sprayed on the diaphragm, the hot pressing and integration operation will be performed, so that the unevenly coated hot melt adhesive that may be caused by spraying is hot pressed, so that the hot melt adhesive layer is smoother and can play a better compensation and repair effect.

[0086] Compared with the prior art, the present invention has at least the following advantages:

[0087] 1. The arc-shaped battery cell 10 of the present invention includes a first hot-melt adhesive coating layer 400 and a second hot-melt adhesive coating layer 500. The first hot-melt adhesive coating layer 400 is bonded to one side of the diaphragm 300, and the second hot-melt adhesive coating layer 500 is bonded to the side of the diaphragm 300 away from the first hot-melt adhesive coating layer 400. When the arc-shaped battery cell 10 is hot-pressed, the first hot-melt adhesive coating layer 400 and the second hot-melt adhesive coating layer 500 have a buffering effect on the stress on the arc-shaped battery cell 10, thereby preventing the arc-shaped battery cell 10 from breaking or failing to shape during the bending process, thereby making the arc-shaped battery cell 10 easier to shape.

[0088] 2. In the arc-shaped battery cell 10 of the present invention, the first hot-melt adhesive coating layer 400 is bonded to one side of the diaphragm 300, the second hot-melt adhesive coating layer 500 is bonded to the side of the diaphragm 300 away from the first hot-melt adhesive coating layer 400, the positive electrode sheet 100 is bonded to the first hot-melt adhesive coating layer 400, and the negative electrode sheet 200 is bonded to the second hot-melt adhesive coating layer 500. When the arc-shaped battery cell 10 is subjected to a hot-pressing forming operation, the first hot-melt adhesive coating layer 400 and the second hot-melt adhesive coating layer 500 begin to melt and penetrate into the various bending parts of the arc-shaped battery cell 10, thereby being able to repair the wrinkles generated during the hot-pressing process and making the surface of the arc-shaped battery cell 10 smoother.

[0089] 3. The first hot melt adhesive coating layer 400 and the second hot melt adhesive coating layer 500 in the arc-shaped battery cell 10 of the present invention begin to melt during hot pressing, making the arc-shaped battery cell 10 easier to form and having better surface flatness. After the arc-shaped battery cell 10 is formed, since the surface of the arc-shaped battery cell 10 returns to room temperature, the first hot melt adhesive coating layer 400 and the second hot melt adhesive coating layer 500 are cooled and solidified again, so that the arc-shaped battery cell 10 maintains the curvature after forming and is not easy to rebound, thereby achieving a better shaping effect.

[0090] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A curved battery cell, characterized in that: The battery cell body comprises a positive electrode ear and a negative electrode ear, wherein the battery cell body comprises a positive electrode sheet, a first hot melt adhesive coating layer, a separator, a second hot melt adhesive coating layer and a negative electrode sheet which are stacked in sequence, wherein the first hot melt adhesive coating layer and the second hot melt adhesive coating layer are both bonded to the separator, the positive electrode sheet is bonded to the first hot melt adhesive coating layer, and the negative electrode sheet is bonded to the second hot melt adhesive coating layer, and the battery cell body is an arc-shaped structure, and the first hot melt adhesive coating layer and the second hot melt adhesive coating layer are used to melt and penetrate into the bending parts of the arc-shaped battery cell during the hot pressing operation, and to keep the arc-shaped battery cell when cooled and solidified again. The arc after forming, the thickness of the middle part of the first hot melt adhesive coating layer is greater than the thickness of the two sides of the first hot melt adhesive coating layer, the thickness of the middle part of the second hot melt adhesive coating layer is greater than the thickness of the two sides of the second hot melt adhesive coating layer, the diaphragm is provided with a first groove and a second groove, the first hot melt adhesive coating layer is provided with a first protrusion, the first protrusion is embedded in the first groove, the second hot melt adhesive coating layer is provided with a second protrusion, the second protrusion is embedded in the second groove, the positive electrode ear is welded to the positive electrode sheet, and the negative electrode ear is welded to the negative electrode sheet; The first hot melt adhesive coating layer includes a first diaphragm coating portion and a first pole ear coating portion, the first diaphragm coating portion is bonded to one side of the diaphragm, the first pole ear coating portion is coated on the connection between the positive electrode sheet and the positive electrode ear, the first pole ear coating portion is connected to the first diaphragm coating portion, the second hot melt adhesive coating layer includes a second diaphragm coating portion and a second pole ear coating portion, the second diaphragm coating portion is bonded to the side of the diaphragm away from the first hot melt adhesive coating layer, the second pole ear coating portion is coated on the connection between the negative electrode sheet and the negative electrode ear, and the second pole ear coating portion is connected to the second diaphragm coating portion.

2. The arc-shaped battery cell according to claim 1, characterized in that: The positive electrode sheet includes a positive electrode current collector, and a plurality of first pores are formed on the positive electrode current collector.

3. The arc-shaped battery cell according to claim 2, characterized in that: The diameter of the first pores is 0.1 mm to 0.4 mm.

4. The arc-shaped battery cell according to claim 1, characterized in that: The negative electrode sheet comprises a negative electrode current collector, and a plurality of second pores are formed on the negative electrode current collector.

5. The arc-shaped battery cell according to claim 4, characterized in that: The diameter of the second pores is 0.1 mm to 0.4 mm.

6. The arc-shaped battery cell according to claim 1, characterized in that: The sum of the thickness of the first hot melt adhesive coating layer and the second hot melt adhesive coating layer is less than the thickness of the diaphragm.

7. The arc-shaped battery cell according to claim 1, characterized in that: The bending direction of the positive electrode sheet and the negative electrode sheet is consistent with the bending direction of the battery cell body.

8. A curved lithium battery, characterized in that: The arc-shaped lithium battery comprises the arc-shaped battery cell as claimed in any one of claims 1 to 7, and the arc-shaped lithium battery further comprises an arc-shaped aluminum-plastic film, wherein the arc-shaped aluminum-plastic film is coated on the outer surface of the arc-shaped battery cell.

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