Soft package battery encapsulation structure facilitating secondary liquid injection

Abstract

The application discloses a soft package battery packaging structure facilitating secondary liquid injection, a thickened area is arranged in the edge sealing area of a conventional soft package battery, the planing surface structure of the thickened area comprises a thickened area metal layer and a thickened area fusion adhesive layer, the thickened area fusion adhesive layer is arranged on the upper and lower surfaces of the thickened area metal layer, and the thickness of the thickened area fusion adhesive layer on the inner surface of the thickened area metal layer is greater than the thickness of the conventional fusion adhesive layer; the soft package battery structure facilitating gradient utilization improves the overall cycle life of the battery, increases the cycle utilization rate of the battery, and can prevent the problem of sudden capacity cliff attenuation of the gradient battery during use, and improves the cycle performance and electrical performance of the battery under the condition of gradient utilization.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a pouch cell packaging structure that facilitates secondary electrolyte injection. Background Technology

[0002] With the advancement of the new energy industry, the application of lithium batteries is becoming more and more widespread, especially with the popularization of new energy vehicles. However, this also leads to a large number of waste new energy vehicle batteries. Although these batteries can no longer meet the needs of new energy vehicles, they can still be reused to meet the needs of other fields such as energy storage. In current lithium battery systems, the cell size continues to expand as cycling progresses, and the formation of internal materials such as SEI continuously consumes the electrolyte available for cell cycling. The reduction in the amount of electrolyte required for cell cycling is a significant factor affecting battery performance.

[0003] During the assembly of battery cells into the casing, electrolyte is injected into the casing, and the electrolyte comes into contact with the cells. After assembly, during battery use, as the battery cycles, the electrolyte in the casing is almost completely consumed in the later stages of the cycle. This results in some active materials in the cells not receiving electrolyte, causing a significant decrease in battery capacity. In addition, as the number of cycles increases, the cells continuously expand. Especially for current high-capacity silicon-containing anode batteries, the volume expansion of silicon is greater than 300%. With the charging and discharging process, silicon expands and contracts in volume, causing changes in cell volume on the one hand, and continuously generating new SEI films (solid or semi-solid films on the positive and negative electrode surfaces due to electrolyte decomposition), resulting in continuous electrolyte consumption and continuous thickening of the cell.

[0004] This results in a sudden and significant capacity decay when existing batteries are used in secondary battery applications due to insufficient electrolyte after cycling, which prevents a large amount of active material from being charged and discharged.

[0005] Application content

[0006] To address the problems existing in the prior art, this application discloses a pouch battery packaging structure that facilitates secondary electrolyte injection. The pouch battery includes a packaging film, a first tab, a second tab, and a battery cell. The battery cell is located within the space enclosed by the packaging film. The first tab and the second tab extend out of the space enclosed by the packaging film and are electrically connected to the battery cell. The packaging film includes an edge sealing area and a perforated area. The battery cell is located within the space enclosed by the perforated area. Electrolyte is also disposed within the space enclosed by the perforated area. The edge sealing area is located outside the space enclosed by the perforated area and is used to seal the space enclosed by the perforated area to prevent the electrolyte from leaving the space enclosed by the perforated area. The edge sealing area is provided with a thickened area. The cross-sectional structure of the thickened area includes a thickened area metal layer, a thickened area inner molten adhesive layer, and a thickened area outer molten adhesive layer. The thickened area outer molten adhesive layer and the thickened area inner molten adhesive layer are respectively disposed on the upper and lower surfaces of the thickened area metal layer. The edge sealing area also includes an inner perimeter area, which is connected to the thickened area and located in the inner circle of the thickened area. The inner perimeter area includes an inner perimeter metal layer, an inner perimeter molten adhesive layer, and an inner perimeter outer molten adhesive layer. The inner perimeter molten adhesive layer and the inner perimeter outer molten adhesive layer are respectively disposed on the upper and lower surfaces of the inner perimeter metal layer. The thickness of the molten adhesive layer on the inner side of the thickened area is greater than that on the inner side of the inner perimeter area. During encapsulation, the sealing area is sealed using hot-pressing tools with the same spacing. Because the thickness of the thickened area is greater than that of the inner perimeter area, the thermal pressure received by the thickened area is also greater than that of the inner perimeter area. This results in the welding thickness of the molten adhesive layers on the inner sides of the two inner perimeter areas to be welded being less than the welding thickness of the molten adhesive layer on the inner side of the thickened area. Furthermore, the thinner molten adhesive layer on the inner side of the inner perimeter area allows the battery cell to more easily break through the welded inner perimeter area during battery use, such as during drops or expansion. This provides space for the battery cell to fall or expand. Due to the greater thickness of the molten adhesive layer on the inner side of the thickened area, it is difficult for the battery cell to break through the thickened area, thus preventing the sealing area from cracking. The sealing area also includes an outer perimeter area, which is connected to the thickened area and located outside the thickened area. The outer perimeter area includes an outer perimeter metal layer, an outer perimeter molten adhesive layer, and an inner perimeter molten adhesive layer. The outer perimeter molten adhesive layer and the inner perimeter molten adhesive layer are respectively disposed on the upper and lower surfaces of the outer perimeter metal layer. The thickness of the inner perimeter molten adhesive layer is greater than the thickness of the inner perimeter molten adhesive layer.

[0007] The thickened area is located between the inner perimeter area and the outer perimeter area. The metal layer of the thickened area connects the metal layer of the inner perimeter area and the metal layer of the outer perimeter area. The inner molten adhesive layer of the thickened area connects the inner molten adhesive layer of the inner perimeter area and the inner molten adhesive layer of the outer perimeter area. The outer molten adhesive layer of the thickened area connects the outer molten adhesive layer of the inner perimeter area and the outer molten adhesive layer of the outer perimeter area.

[0008] Before encapsulation, the vertical distance from the outer surface of the inner molten adhesive layer of the peripheral area to the metal layer of the peripheral area is not less than the vertical distance from the inner molten adhesive layer of the thickened area to the metal layer of the peripheral area. This reduces the amount of adhesive overflow from the inner molten adhesive layer of the thickened area to the inner molten adhesive layer of the peripheral area during encapsulation, thereby further strengthening the encapsulation strength of the thickened area after encapsulation. Since the thickness of both the inner molten adhesive layer of the thickened area and the inner molten adhesive layer of the peripheral area is greater than the thickness of the conventional molten adhesive layer, it facilitates the injection needle passing through the inner molten adhesive layer of the peripheral area and through the sealing area during secondary liquid replenishment.

[0009] The edge sealing area includes an electrode edge sealing area and a side edge sealing area. The first electrode and the second electrode pass through the electrode edge sealing area. The electrode edge sealing area is provided with an outer perimeter area, a thickened area, and an inner perimeter area.

[0010] The side sealing area is located on both sides of the tab sealing area, and the side sealing area is provided with the outer area, the thickened area and the inner area.

[0011] The thickness of the inner molten adhesive layer in the inner perimeter area is less than the thickness of the outer molten adhesive layer in the inner perimeter area. The thickness of the inner molten adhesive layer in the inner perimeter area ranges from 20-30 μm, and the thickness of the inner molten adhesive layer in the thickened area ranges from 50-70 μm. The metal layer in the thickened area has an arc-shaped structure that protrudes outward from the thickened area. This allows for the placement of more thickened molten adhesive layers between the metal layers in the thickened area. Furthermore, since the arc-shaped structure does not produce sharp edges, it prevents the metal layer from puncturing the molten adhesive layer during the heat sealing process. The thickness of the inner molten adhesive layer in the thickened area is calculated as the vertical distance from the upper surface of the inner molten adhesive layer in the thickened area to the lowest point of the arc-shaped structure.

[0012] The encapsulation film also includes a folded area, which is located between the two punched areas. The two ends of the folded area are connected to the sealing area. The folded area includes a folded area metal layer and an inner folded area molten adhesive layer and an outer folded area molten adhesive layer located on the upper and lower surfaces of the folded area metal layer. The thickness of the inner folded area molten adhesive layer is less than the thickness of the outer folded area molten adhesive layer.

[0013] The thickness of the molten adhesive layer inside the folded area is the same as the thickness of the molten adhesive layer inside the inner perimeter area; thus, during cell drop, expansion, or secondary liquid injection, the molten adhesive layer inside the folded area and the molten adhesive layer inside the inner perimeter area are stretched apart, thereby providing buffering or liquid injection space. The folded area is provided with two thickened areas, which are symmetrically arranged with respect to the center line of the folded area. The folded area may also not be provided with thickened areas. Whether to provide thickened areas depends on the width and bending condition of the folded area.

[0014] The battery cell includes a negative electrode sheet, and the negative electrode active material in the negative electrode sheet includes silicon.

[0015] The method disclosed in this application has the following advantages: This application addresses this issue by setting a thickened area. During encapsulation, the sealing area is sealed using hot-pressing tools with the same spacing. Since the thickness of the thickened area is greater than that of the inner perimeter area, the thermal pressure received by the thickened area is also greater than that of the inner perimeter area. This results in the welding thickness of the inner molten adhesive layer of the two inner perimeter areas to be welded being less than that of the inner molten adhesive layer of the thickened area. Furthermore, the thinner inner molten adhesive layer of the inner perimeter area makes it easier for the battery cell to break through the welded inner perimeter area during battery use, such as during drops or expansion. This provides space for the battery cell to fall or expand. Due to the greater thickness of the inner molten adhesive layer of the thickened area, it is difficult for the battery cell to break through the thickened area, thus preventing the sealing area from cracking. Moreover, the thickness of the inner molten adhesive layer of the thickened area is greater than that of the conventional inner molten adhesive layer of existing aluminum-plastic film, while the thickness of the inner molten adhesive layer of the inner perimeter area is less than that of the conventional inner molten adhesive layer of existing aluminum-plastic film. This makes it easier for the inner perimeter area to be broken through during drops or expansion, providing a buffer space, while the thickened area is more difficult to break through, thus preventing cracking. Because the vertical distance from the outer surface of the inner molten adhesive layer of the outer perimeter area to the metal layer of the outer perimeter area is not less than the vertical distance from the inner molten adhesive layer of the thickened area to the metal layer of the outer perimeter area, the overflow of the inner molten adhesive layer of the thickened area to the inner molten adhesive layer of the outer perimeter area during the encapsulation process is reduced, thereby further strengthening the encapsulation strength of the thickened area after encapsulation. Since the thickness of both the inner molten adhesive layer of the thickened area and the inner molten adhesive layer of the outer perimeter area is greater than that of the conventional molten adhesive layer, it is easier for the injection needle to pass through the inner molten adhesive layer of the outer perimeter area and through the sealing area during secondary electrolyte replenishment. A small injection tube made of the same material as the molten adhesive layer of the thickened area can be inserted between the inner molten adhesive layers of the outer perimeter area and the thickened area, extending into the space enclosed by the pit area, to inject electrolyte into the used battery. This replenishes the electrolyte in the used battery cell, preventing the positive and negative electrode active materials in the cell from failing due to lack of electrolyte contact, or even large-scale failure, which could cause battery capacity decay or even a sudden precipitous capacity decay. This improves the overall cycle life of the battery and increases its recycling rate. Furthermore, after refilling, the small injection tube does not need to be removed. The outer and thickened areas can be directly heat-sealed. Since the material of the small injection tube is the same as that of the molten adhesive layer in the thickened area, the sealing performance can be improved. After heat sealing, the protruding small injection tube can be cut short from the outside of the battery. This method avoids removing the injection tube, thus preventing external air from entering the battery during and after the injection process, which could affect the battery's cycle performance. The positive and negative electrode materials and electrolyte of the battery cell are very sensitive to air, especially water and oxygen in the air. In addition, the small injection tube is inserted into the space enclosed by the thickened area and the pitted area. Before injection, the space can be evacuated through the small injection tube. Due to the decomposition of the electrolyte during battery cycling, gas will be generated, which can cause the battery to bulge and pose a safety risk. Evacuating the air before injection can reduce the probability of bulging and prevent safety hazards. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0017] Figure 1 This is a top view of the encapsulation film of the conventional soft-pack battery of this application before the pitting.

[0018] Figure 2 This is a top view of the encapsulation film of the conventional soft-pack battery of this application after being perforated, and a schematic diagram of the cross-sectional positions at vertical sections AA and BB.

[0019] Figure 3 This is a front view of the encapsulation film of a conventional soft-pack battery after denting.

[0020] Figure 4 This application Figure 2 A schematic diagram of the encapsulation film of a conventional soft-pack battery and its cross-section after being cut by section AA and section BB.

[0021] Figure 5 This is a perspective view of the conventional soft-pack battery after packaging, and a schematic diagram of the vertical section cutting position of EE.

[0022] Figure 6 This is a front view and enlarged view of the vertical section of EE after conventional soft-pack battery packaging according to this application, and a schematic diagram of the position D.

[0023] Figure 7 This application Figure 6 A magnified view of position D in the middle.

[0024] Figure 8 This is a top view of the encapsulation film perforation of the soft-pack battery encapsulation structure that facilitates secondary electrolyte injection, as described in this application.

[0025] Figure 9 This is a top view of the encapsulation film after denting in the soft-pack battery encapsulation structure of the present application, which has no thickened area in the folded region and facilitates secondary liquid injection, and a schematic diagram of the cross-sectional positions of vertical section AA and vertical section BB.

[0026] Figure 10 This is a front view of the encapsulation film after denting in the soft-pack battery encapsulation structure that facilitates secondary electrolyte injection, as described in this application.

[0027] Figure 11 This application Figure 9 A schematic diagram of the cross-section of the encapsulation film of a soft-pack battery encapsulation structure with a uniform thickness of the melt layer on the inner side of the middle and outer perimeter, which facilitates secondary liquid injection, after being cut by section AA.

[0028] Figure 12 This application Figure 9A schematic diagram of the cross-section of the encapsulation film of a soft-pack battery encapsulation structure with a uniform thickness of the melt layer on the inner side of the middle and outer perimeter, which facilitates secondary liquid injection, after being cut by section BB.

[0029] Figure 13 This application Figure 9 A schematic diagram of the encapsulation film of a soft-pack battery encapsulation structure with a gradually thickening inner molten adhesive layer in the outer periphery, facilitating secondary liquid injection, after being cut by section AA.

[0030] Figure 14 This application Figure 9 A schematic diagram of the encapsulation film of a soft-pack battery encapsulation structure with a gradually thickening inner molten adhesive layer in the outer periphery, facilitating secondary liquid injection, after being cut by section BB.

[0031] Figure 15 This is a perspective view of the soft-pack battery that facilitates secondary electrolyte injection according to this application, and a schematic diagram of the vertical section cut position of EE.

[0032] Figure 16 This is a top view of the encapsulation film after denting in the soft-pack battery encapsulation structure of this application, which features two thickened areas in the folded region to facilitate secondary electrolyte injection.

[0033] Figure 17 This application Figure 15 A front view and enlarged view of the vertical section of the EE after the soft-pack battery is packaged for easy secondary electrolyte injection, showing the direction of the cut.

[0034] Figure 18 This application Figure 17 An enlarged view of the enlarged position D of the soft-pack battery structure package that is easy to reuse in a tiered manner.

[0035] Figure 19 This is a perspective view of the soft-pack battery that facilitates secondary electrolyte injection according to this application, and a schematic diagram of the vertical section cutting position of CC and the horizontal section cutting position of DD.

[0036] Figure 20 This application Figure 19 A top view of a soft-pack battery, designed for easy secondary electrolyte injection, after being cut at the DD section.

[0037] Figure 21 This application Figure 19 A front view of a soft-pack battery, designed for easy secondary electrolyte injection, after being cut at the CC section.

[0038] Figure 22 This application Figure 20 and Figure 21 Enlarged view of position D or E and schematic diagram of injection needle insertion structure. Implementation

[0039] The technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application; The present application will be further described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application. The technical solutions of the embodiments of the present application will be clearly and completely described below; the directional expressions involved in the present application, such as "up" and "down," are all positioned according to the view arrangement of the present application.

[0040] Figure 1-7 This is a schematic diagram of a conventional pouch cell and its packaging process. Figure 1 This is a top view of the encapsulation film 11 of the conventional soft-pack battery of this application before the pit is punched. Most existing encapsulation films 11 are made of aluminum-plastic film, including a conventional metal layer 1101 and conventional molten adhesive layers 1102 located on the upper and lower sides of the conventional metal layer 1101. The material of the conventional metal layer 1101 is generally aluminum foil, the material of the conventional molten adhesive layer 1102 located in the inner layer of the encapsulation is generally a polypropylene layer, and the material of the conventional molten adhesive layer 1102 located in the outer layer of the encapsulation is generally a nylon layer. During hot pressing encapsulation, the polypropylene layers of the two aluminum-plastic films are fused together by heat. The thickness of the polypropylene layer of the existing aluminum-plastic film is generally 40-50um. The sealing area 111 formed after fusion encapsulation with this thickness is difficult to be opened by the dropped or expanded battery cell 20, and therefore cannot provide a buffer space for the battery cell 20 in the encapsulation structure. Especially during the secondary electrolyte injection process of the secondary cell 20, for existing secondary soft-pack batteries, the expansion of the cell 20 occupies most of the space in the perforated area 112 formed by the aluminum-plastic film encapsulation, and a large part of the sealing area 111 of the aluminum-plastic film also expands, resulting in insufficient electrolyte storage and difficulty in secondary electrolyte injection. Before perforation, the encapsulation film 11 is a planar structure. The centerline of the encapsulation film 11 to be perforated is bent in advance, and perforation is performed on both sides of the bend.

[0041] Figure 2 This is a top view of the encapsulation film 11 of the conventional soft-pack battery of this application after being punched, which forms a sealing area 111, a folded area 116 and a punched area 112. Figure 3 This is a front view of the encapsulation film 11 of the conventional soft-pack battery of this application after being perforated. Figure 4 This application Figure 2 The encapsulation film 11 of a conventional soft-pack battery and its cross-section after being cut by section AA and section BB show that the encapsulation film 11 is composed of three layers. Figure 5 This is a perspective view of the conventional pouch battery after packaging, and a schematic diagram of the vertical section cut position of EE. The vertical section of EE is perpendicular to the upper surface of the pouch battery, parallel to the front side of the pouch battery (the side seen in the front view), and is cut at the tab position. Figure 6 This is a front view and enlarged view of the vertical section of EE after conventional soft-pack battery packaging according to this application, and a schematic diagram of the position D. Figure 7 This application Figure 6 A magnified view of position D in the middle, and Figure 7 The thickness of the conventional molten adhesive layer 1102 on the inner side (near the tab side) of the conventional metal layer 1101 is less than the thickness of the conventional molten adhesive layer 1102 on the outer side of the conventional metal layer 1101. This is because the sealing area 111 is encapsulated using a hot melt sealing method. During the hot melt sealing process, the conventional molten adhesive layer 1102 on the inner side of the conventional metal layer 1101 is fused together by heat and pressure, and the corresponding thickness will decrease.

[0042] A conventional pouch battery (and the pouch battery structure for easy reuse in this application also includes the following structure) includes an encapsulation film 11, a first tab 21, a second tab 22, and a battery cell 20. The battery cell is located within the space enclosed by the encapsulation film 11. The first tab 21 and the second tab 22 extend out of the space enclosed by the encapsulation film 11 and are electrically connected to the battery cell 20. The encapsulation film 11 includes a sealing area 111 and a perforated area 112. The battery cell 20 is located within the space enclosed by the encapsulation film 11. Within the space enclosed by the pitted area 112, an electrolyte is also provided. The sealing area 111 is located outside the space enclosed by the pitted area 112. The sealing area 111 is used to seal the space enclosed by the pitted area 112 to prevent the electrolyte from leaving the space enclosed by the pitted area 112. The cross-sectional structure of the encapsulation film 11 includes a conventional metal layer 1101 and a conventional molten adhesive layer 1102. The conventional molten adhesive layer 1102 is disposed on the upper and lower surfaces of the conventional metal layer 1101.

[0043] To address the problems existing in the current technology, such as Figure 8-22 As shown, this application discloses a pouch battery packaging structure that facilitates secondary electrolyte injection. The pouch battery includes a packaging film 11, a first tab 21, a second tab 22, and a battery cell 20. The battery cell 20 is located within the space enclosed by the packaging film 11. The first tab 21 and the second tab 22 extend out of the space enclosed by the packaging film 11 and are electrically connected to the battery cell 20. The packaging film 11 includes a sealing area 111 and a perforated area 112. The battery cell 20 is located within the space enclosed by the perforated area 112. Electrolyte is also disposed within the space enclosed by the perforated area 112. The sealing area 111 is located outside the space enclosed by the perforated area 112 and is used to seal the space enclosed by the perforated area 112 to prevent the electrolyte from leaving the space enclosed by the perforated area 112. The edge sealing area 111 is provided with a thickened area 113. The cross-sectional structure of the thickened area 113 includes a thickened area metal layer 1131, a thickened area inner molten adhesive layer 1132, and a thickened area outer molten adhesive layer 1133. The thickened area outer molten adhesive layer 1133 and the thickened area inner molten adhesive layer 1132 are respectively disposed on the upper and lower surfaces of the thickened area metal layer 1131. The sealing area 111 also includes an inner perimeter area 1110, which is connected to the thickened area 113 and located in the inner circle of the thickened area 113. The inner perimeter area 1110 includes an inner perimeter metal layer 1111, an inner perimeter inner molten adhesive layer 1112, and an inner perimeter outer molten adhesive layer 1113. The inner perimeter inner molten adhesive layer 1112 and the inner perimeter outer molten adhesive layer 1113 are respectively disposed on the upper and lower surfaces of the inner perimeter metal layer 1111. The thickness of the inner molten adhesive layer 1132 of the thickened area is greater than the thickness of the inner molten adhesive layer 1112 of the inner perimeter area. During encapsulation, the sealing area 111 is sealed using a hot-pressing tool with the same spacing. Since the thickness of the thickened area 113 is greater than that of the inner perimeter area 1110, the thermal pressure received by the thickened area 113 is also greater than that of the inner perimeter area 1110. This results in the welding thickness of the inner molten adhesive layers 1112 of the two inner perimeter areas to be welded being less than the welding thickness of the inner molten adhesive layer 1132 of the thickened area. Furthermore, the inner molten adhesive layer 1112 of the inner perimeter area is thinner, making it easier for the cell 20 to break through the welded inner perimeter area 1110 during battery use, such as when it is dropped or expands. This provides space for the cell 20 to fall or expand. Because the inner molten adhesive layer 1132 of the thickened area is thicker, it is difficult for the cell 20 to break through the thickened area 113, thus preventing the sealing area 111 from cracking.

[0044] The sealing area 111 also includes an outer area 1114, which is connected to the thickened area 113 and located outside the thickened area 113. The outer area 1114 includes an outer metal layer 1115, an outer molten adhesive layer 1117, and an inner molten adhesive layer 1116. The outer molten adhesive layer 1117 and the inner molten adhesive layer 1116 are respectively disposed on the upper and lower surfaces of the outer metal layer 1115. The thickness of the inner molten adhesive layer 1116 is greater than the thickness of the inner molten adhesive layer 1112.

[0045] The thickened area 113 is located between the inner perimeter area 1110 and the outer perimeter area 1114. The thickened area metal layer 1131 connects the inner perimeter metal layer 1111 and the outer perimeter metal layer 1115. The thickened area inner molten adhesive layer 1132 connects the inner perimeter inner molten adhesive layer 1112 and the outer perimeter inner molten adhesive layer 1116. The thickened area outer molten adhesive layer 1133 connects the inner perimeter outer molten adhesive layer 1113 and the outer perimeter outer molten adhesive layer 1117.

[0046] Before encapsulation, the vertical distance from the outer surface of the inner molten adhesive layer 1116 of the outer perimeter area to the metal layer 1115 of the outer perimeter area is not less than the vertical distance from the inner molten adhesive layer 1132 of the thickened area to the metal layer 1115 of the outer perimeter area. This reduces the amount of adhesive overflow from the inner molten adhesive layer 1132 of the thickened area to the inner molten adhesive layer 1116 of the outer perimeter area during the encapsulation process, thereby further strengthening the encapsulation strength of the thickened area 113 after encapsulation. Since the thicknesses of the inner molten adhesive layer 1132 of the thickened area and the inner molten adhesive layer 1116 of the outer perimeter area are both greater than the thickness of the conventional molten adhesive layer 1102, it facilitates the injection needle 3 to pass through the inner molten adhesive layer 1116 of the outer perimeter area and through the sealing area 111 during the secondary liquid replenishment process.

[0047] The edge sealing area 111 includes an electrode edge sealing area 1115111 and a side edge sealing area 1114111. The first electrode 21 and the second electrode 22 pass through the electrode edge sealing area 1115111. The outer perimeter area 1114, the thickened area 113 and the inner perimeter area 1110 are provided inside the electrode edge sealing area 1115111.

[0048] The side sealing area 1114111 is located on both sides of the tab sealing area 1115111, and the side sealing area 1114111 is provided with the outer area 1114, the thickened area 113 and the inner area 1110.

[0049] The thickness of the inner molten adhesive layer 1112 of the inner perimeter is less than the thickness of the outer molten adhesive layer 1113 of the inner perimeter. The thickness of the inner molten adhesive layer 1112 of the inner perimeter ranges from 20 to 30 μm, and the thickness of the inner molten adhesive layer 1132 of the thickened area ranges from 50 to 70 μm. The metal layer 1131 of the thickened area has an arc-shaped structure that protrudes outward from the thickened area 113, thereby allowing for more thickened area 113 molten adhesive layers to be set between the metal layers within the thickened area 113. Furthermore, since the arc-shaped structure does not produce sharp edges, it prevents the metal layer from puncturing the molten adhesive layer during the heat sealing process. The thickness of the inner molten adhesive layer 1132 of the thickened area is calculated as the vertical distance from the upper surface of the inner molten adhesive layer 1132 of the thickened area to the lowest point of the arc-shaped structure.

[0050] The encapsulation film 11 further includes a folded area 116, which is located between the two punched areas 112. The two ends of the folded area 116 are connected to the sealing area 111. The folded area 116 includes a folded area metal layer 1161 and an inner folded area molten adhesive layer 1162 and an outer folded area molten adhesive layer 1163 located on the upper and lower surfaces of the folded area metal layer 1161. The thickness of the inner folded area molten adhesive layer 1162 is less than the thickness of the outer folded area molten adhesive layer 1163.

[0051] The thickness of the inner molten adhesive layer 1162 of the folded area is the same as the thickness of the inner molten adhesive layer 1112 of the inner perimeter area; thus, during the drop, expansion, or secondary liquid injection of the battery cell 20, the inner molten adhesive layer 1162 of the folded area and the inner molten adhesive layer 1112 of the inner perimeter area are stretched apart, thereby providing a buffer or liquid injection space. The folded area 116 is provided with two thickened areas 113, which are symmetrically arranged with respect to the center line of the folded area 116. The folded area 116 may also not be provided with thickened areas 113. Whether to provide thickened areas 113 depends on the width and bending condition of the folded area 116.

[0052] The battery cell 20 includes a negative electrode sheet, and the negative electrode active material in the negative electrode sheet includes silicon.

[0053] The method disclosed in this application has the following advantages: This application addresses this issue by setting a thickened area 113. During encapsulation, the sealing area 111 is sealed using a hot-pressing tool with the same spacing. Since the thickness of the thickened area 113 is greater than that of the inner perimeter area 1110, the thermal pressure received by the thickened area 113 is also greater than that of the inner perimeter area 1110. This results in the welding thickness of the inner molten adhesive layer 1112 of the two inner perimeter areas to be welded being less than the welding thickness of the inner molten adhesive layer 1132 of the thickened area. Furthermore, the thinner inner molten adhesive layer 1112 of the inner perimeter area makes it easier for the cell 20 to break through the welded inner perimeter area 1111 during battery use, in the event of drops, expansion, or other incidents. 110, thus providing space for the battery cell 20 to fall or expand. Due to the large thickness of the inner molten adhesive layer 1132 of the thickened area, it is difficult for the battery cell 20 to break through the thickened area 113, thereby preventing the sealing area 111 from cracking. Furthermore, the thickness of the inner molten adhesive layer 1132 of the thickened area is greater than the thickness of the conventional inner molten adhesive layer 1102 of the existing aluminum-plastic film, while the thickness of the inner molten adhesive layer 1112 of the inner perimeter area is less than the thickness of the conventional inner molten adhesive layer 1102 of the existing aluminum-plastic film. This makes it easier for the inner perimeter area 1110 to be broken open and provide buffer space when falling or expanding, but the thickened area 113 is more difficult to be broken open, thereby preventing cracking. Since the vertical distance from the outer surface of the inner molten adhesive layer 1116 of the outer perimeter region to the metal layer 1115 of the outer perimeter region is not less than the vertical distance from the inner molten adhesive layer 1132 of the thickened region to the metal layer 1115 of the outer perimeter region, the amount of adhesive overflow from the inner molten adhesive layer 1132 of the thickened region to the inner molten adhesive layer 1116 of the outer perimeter region during the encapsulation process is reduced, thereby further strengthening the encapsulation strength of the thickened region 113 after encapsulation. Since the thickness of the inner molten adhesive layer 1132 of the thickened area and the inner molten adhesive layer 1116 of the outer area are both greater than the thickness of the conventional molten adhesive layer 1102, it is convenient for the injection needle 3 to pass through the inner molten adhesive layer 1116 of the outer area and through the sealing area 111 during the secondary replenishment process. It can inject electrolyte into the used battery through a small injection tube made of the same material as the molten adhesive layer of the thickened area 113. By inserting the small injection needle 3 between the inner molten adhesive layers of the outer area 1114 and the thickened area 113 and into the space enclosed by the pit area 112, electrolyte is injected into the used battery. This replenishes the electrolyte in the used cell 20, preventing the positive and negative electrode active materials in the cell 20 from failing due to lack of contact with electrolyte or even large-scale failure, which would cause battery capacity decay or even a sudden cliff-like capacity decay. This improves the overall cycle life of the battery and increases the battery's recycling rate. Furthermore, after refilling, the small injection needle 3 does not need to be removed. The outer area 1114 and the thickened area 113 can be directly heat-sealed. Since the material of the small injection needle 3 is the same as that of the molten adhesive layer of the thickened area 113, the sealing performance can be improved. After heat sealing, the protruding small injection needle 3 can be cut short from the outside of the battery. This method does not require removing the injection needle 3, thus preventing external air from entering the battery during and after the injection process, which would affect the battery's cycle performance. The positive and negative electrode materials and electrolyte of the cycled cell 20 are very sensitive to air, especially water and oxygen in the air. In addition, the small injection needle 3 is inserted into the thickened area 113 and extends into the space enclosed by the pitted area 112. Before injection, the space can be evacuated by the small injection needle 3. Due to the decomposition of the electrolyte during battery cycling, gas will be generated, which can cause the battery to bulge and pose a safety risk. By evacuating the air before injection, the probability of bulging can be reduced, preventing safety hazards.

Claims

1. A pouch battery packaging structure for easy secondary electrolyte filling, the pouch battery for easy secondary electrolyte filling includes a packaging film, a first tab, a second tab, and a battery cell, the battery cell being located within a space enclosed by the packaging film, the first tab and the second tab extending outwards from the space enclosed by the packaging film, the first tab and the second tab being electrically connected to the battery cell respectively, the packaging film including an edge sealing area and a perforated area, the battery cell being located within a space enclosed by the perforated area, the space enclosed by the perforated area also containing electrolyte, the edge sealing area being located outside the space enclosed by the perforated area, the edge sealing area being used to seal the space enclosed by the perforated area to prevent the electrolyte from leaving the space enclosed by the perforated area; Its features are, The edge sealing area is provided with a thickened area. The cross-sectional structure of the thickened area includes a thickened area metal layer, a thickened area inner molten adhesive layer, and a thickened area outer molten adhesive layer. The thickened area outer molten adhesive layer and the thickened area inner molten adhesive layer are respectively disposed on the upper and lower surfaces of the thickened area metal layer. The edge sealing area also includes an inner perimeter area, which is connected to the thickened area and located in the inner circle of the thickened area. The inner perimeter area includes an inner perimeter metal layer, an inner perimeter molten adhesive layer, and an inner perimeter outer molten adhesive layer. The inner perimeter molten adhesive layer and the inner perimeter outer molten adhesive layer are respectively disposed on the upper and lower surfaces of the inner perimeter metal layer. Wherein, before encapsulation, the thickness of the inner molten adhesive layer of the thickened area is greater than the thickness of the inner molten adhesive layer of the inner perimeter area; The sealing area also includes an outer perimeter area, which is connected to the thickened area and located outside the thickened area. The outer perimeter area includes an outer perimeter metal layer, an outer perimeter molten adhesive layer, and an inner perimeter molten adhesive layer. The outer perimeter molten adhesive layer and the inner perimeter molten adhesive layer are respectively disposed on the upper and lower surfaces of the outer perimeter metal layer. The thickness of the inner perimeter molten adhesive layer is greater than the thickness of the inner perimeter molten adhesive layer. Before encapsulation, the vertical distance from the outer surface of the inner molten adhesive layer of the peripheral area to the metal layer of the peripheral area is not less than the vertical distance from the inner molten adhesive layer of the thickened area to the metal layer of the peripheral area. The thickness of the inner molten adhesive layer in the inner perimeter area ranges from 20 to 30 μm, and the thickness of the inner molten adhesive layer in the thickened area ranges from 50 to 70 μm. The encapsulation film also includes a folded area located between the two punched areas. The two ends of the folded area are connected to the sealing area. The folded area includes a folded area metal layer and an inner folded area molten adhesive layer and an outer folded area molten adhesive layer located on the upper and lower surfaces of the folded area metal layer. The thickness of the inner folded area molten adhesive layer is less than the thickness of the outer folded area molten adhesive layer. The folded area is provided with two thickened areas, which are symmetrically arranged with respect to the center line of the folded area.

2. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 1, characterized in that, The thickened area is located between the inner perimeter area and the outer perimeter area. The metal layer of the thickened area connects the metal layer of the inner perimeter area and the metal layer of the outer perimeter area. The inner molten adhesive layer of the thickened area connects the inner molten adhesive layer of the inner perimeter area and the inner molten adhesive layer of the outer perimeter area. The outer molten adhesive layer of the thickened area connects the outer molten adhesive layer of the inner perimeter area and the outer molten adhesive layer of the outer perimeter area.

3. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 1, characterized in that, The edge sealing area includes an electrode edge sealing area and a side edge sealing area. The first electrode and the second electrode pass through the electrode edge sealing area. The electrode edge sealing area is provided with an outer perimeter area, a thickened area, and an inner perimeter area.

4. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 3, characterized in that, The side sealing area is located on both sides of the tab sealing area, and the side sealing area is provided with the outer area, the thickened area and the inner area.

5. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 1, characterized in that, The thickness of the inner side of the inner enclosure is less than the thickness of the outer side of the inner enclosure.

6. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 1, characterized in that, The thickened metal layer has an arc-shaped structure that protrudes outward from the thickened area.

7. The soft-pack battery packaging structure for easy secondary electrolyte injection according to claim 1, characterized in that, The battery cell includes a negative electrode sheet, and the negative electrode active material in the negative electrode sheet includes silicon.

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