Laminated battery cell

Abstract

The utility model provides a laminated battery cell. The laminated battery cell comprises at least one negative plate, and the negative plate comprises a negative main body and a negative lug connected with the negative main body; the positive plate comprises a positive main body and a positive lug connected with the positive main body, and the positive plate and the negative plate are alternately arranged along the first direction; the diaphragm layer is arranged between the positive plate and the negative plate and is used for separating the positive plate from the negative plate; wherein a negative electrode thinning area is arranged on one side, close to the negative tab, of the negative electrode main body, a near-side thinning area is arranged on one side, close to the positive tab, of the positive electrode main body, and a far-side thinning area is arranged on one side, away from the positive tab, of the positive electrode main body. According to the technical scheme provided by the utility model, the problems that a laminated battery cell in the prior art is easy to have the risk of lithium precipitation and is not beneficial to the safe use of the battery cell are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of battery, specifically, relate to a lamination type electric core. BACKGROUND

[0002] Lithium ion battery has the advantages of good cycle performance, high energy density, low self-discharge rate, wide working temperature range, no memory effect and green pollution-free. Therefore, new energy vehicles usher in a period of rapid development, and lithium ion batteries are used more and more widely in new energy vehicles.

[0003] The development direction of lithium ion is pure electrification, and it is imperative to improve the energy density of the electric core. In the prior art, during the manufacturing process of the electric core, only the positive electrode layer near the positive electrode tab side and the negative electrode layer near the negative electrode tab side are thinned, which can easily lead to a negative side N / P ratio less than 1, so that the negative electrode tab side has the risk of lithium precipitation, which is not conducive to the safe use of the electric core. UTILITY MODEL CONTENT

[0004] The main purpose of the utility model is to provide a lamination type electric core to solve the problem that the lamination type electric core in the prior art has the risk of lithium precipitation and is not conducive to the safe use of the electric core.

[0005] In order to achieve the above purpose, the application provides a lamination type electric core, which comprises at least one negative electrode sheet, the negative electrode sheet comprising a negative electrode main body and a negative electrode tab connected with the negative electrode main body; at least one positive electrode sheet, the positive electrode sheet comprising a positive electrode main body and a positive electrode tab connected with the positive electrode main body, the positive electrode sheet and the negative electrode sheet being arranged alternately along a first direction; a diaphragm layer, the diaphragm layer being arranged between the positive electrode sheet and the negative electrode sheet for separating the positive electrode sheet and the negative electrode sheet; wherein, the side of the negative electrode main body close to the negative electrode tab is provided with a negative electrode thinning area, the side of the positive electrode main body close to the positive electrode tab is provided with a proximal thinning area, and the side of the positive electrode main body away from the positive electrode tab is provided with a distal thinning area.

[0006] Further, the negative electrode main body comprises a negative current collector and a negative electrode coating layer, both sides of the negative current collector are provided with the negative electrode coating layer in the first direction, the negative electrode thinning area is arranged on the negative electrode coating layer, and the negative electrode thinning area is recessed in the negative electrode coating layer.

[0007] Further, the negative electrode thinning area has a first surface, the first surface is inclinedly arranged on the negative electrode coating layer, and the distance between the first surface and the negative current collector gradually decreases from the negative electrode main body to the side close to the negative electrode tab.

[0008] Further, the included angle A1 between the first surface and the negative current collector is in the range of 20°-40°.

[0009] Further, the length L1 of the first surface in the second direction is 5mm-10mm.

[0010] Further, the positive electrode body includes a positive current collector and positive electrode coating layers, both sides of the positive current collector are provided with the positive electrode coating layers in the first direction, the positive electrode coating layers are provided with a proximal thinning area and a distal thinning area, at least one of the proximal thinning area and the distal thinning area is recessed into the positive electrode coating layer.

[0011] Further, the proximal thinning area has a second surface, the second surface is obliquely arranged on the positive electrode coating layer, from the positive electrode body to the direction close to the positive electrode tab, the distance between the second surface and the positive current collector gradually decreases; and / or, the proximal thinning area has a third surface, the third surface is obliquely arranged on the positive electrode coating layer, from the positive electrode body to the direction away from the positive electrode tab, the distance between the third surface and the positive current collector gradually decreases.

[0012] Further, the length L2 of at least one of the second surface and the third surface in the second direction is 10mm to 15mm.

[0013] Further, the included angle A2 between at least one of the second surface and the third surface and the positive current collector is 20° to 40°.

[0014] Further, along the second direction, the laminated battery cell has a first side and a second side arranged oppositely, the negative electrode tab is located on the first side, and the positive electrode tab is located on the second side, and the first direction and the second direction are arranged at an included angle.

[0015] The technical scheme of the utility model is that the thinning area is arranged on the side of the positive electrode tab and the side away from the positive electrode tab of the positive electrode sheet (that is, the proximal thinning area is arranged on the side close to the positive electrode tab of the positive electrode body, and the distal thinning area is arranged on the side away from the positive electrode tab of the positive electrode body), and the thinning area is arranged on the side of the negative electrode tab of the negative electrode sheet (that is, the negative thinning area is arranged on the side close to the negative electrode tab of the negative electrode body), so that the N / P ratio of the battery cell at each position can be ensured to be greater than 1, the N / P ratio refers to the capacity ratio of the negative electrode material and the positive electrode material, keeping the N / P ratio greater than 1 can solve the risk of lithium precipitation on the side of the negative electrode layer of the laminated battery, so as to effectively reduce the risk of lithium precipitation of the lithium ion battery in the charging and discharging process, and improve the safety and cycle performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of this application serve to provide a further understanding of the utility model, the schematic embodiments of the utility model and the description thereof serve to explain the utility model, and do not constitute an improper limitation on the utility model. In the drawings:

[0017] Figure 1 The structure schematic view of the embodiment of the laminated battery cell of the utility model is shown;

[0018] Figure 2 The partial structure schematic view of the laminated battery cell of Figure 1 is shown;

[0019] Figure 3 a top view of the laminated battery cell of Figure 1

[0020] Figure 4 a partial structural schematic view of the laminated battery cell of Figure 1

[0021] Wherein, the above drawings include the following reference signs:

[0022] 3, diaphragm layer; 11, negative electrode main body; 111, negative current collector; 112, negative electrode coating layer; 12, negative electrode tab; 13, negative electrode thinning area; 131, first surface; 21, positive electrode main body; 211, positive current collector; 212, positive electrode coating layer; 22, positive electrode tab; 23, proximal thinning area; 24, distal thinning area; 231, second surface; 241, third surface. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0024] It should be noted that the laminated battery cell in the embodiments of the present application is a thermal composite laminated battery cell and a Z-stacked laminated battery cell.

[0025] As shown in Figures 1 to 3 The embodiments of the present application provide a laminated battery cell. The laminated battery cell comprises: at least one negative electrode sheet, comprising a negative electrode main body 11 and a negative electrode tab 12 connected with the negative electrode main body 11; at least one positive electrode sheet, comprising a positive electrode main body 21 and a positive electrode tab 22 connected with the positive electrode main body 21, the positive electrode sheet and the negative electrode sheet are arranged alternately along a first direction; a diaphragm layer 3, the diaphragm layer 3 is arranged between the positive electrode sheet and the negative electrode sheet, and the diaphragm layer 3 is used for separating the positive electrode sheet and the negative electrode sheet; wherein, a negative electrode thinning area 13 is arranged on the side of the negative electrode main body 11 close to the negative electrode tab 12, a proximal thinning area 23 is arranged on the side of the positive electrode main body 21 close to the positive electrode tab 22, and a distal thinning area 24 is arranged on the side of the positive electrode main body 21 away from the positive electrode tab 22.

[0026] ​​In the above technical solution, thinning zones are provided on the tab side and the side away from the tab of the positive electrode sheet (i.e., a proximal thinning zone 23 is provided on the side of the positive electrode body 21 close to the positive tab 22, and a distal thinning zone 24 is provided on the side of the positive electrode body 21 away from the positive tab 22), and a thinning zone is provided on the tab side of the negative electrode sheet (i.e., a negative electrode thinning zone 13 is provided on the side of the negative electrode body 11 close to the negative tab 12). This ensures that the N / P ratio of the battery cell at each position is greater than 1. The N / P ratio refers to the capacity ratio of the negative electrode material to the positive electrode material. Maintaining an N / P ratio greater than 1 can solve the risk of lithium plating on the tab side of the stacked negative electrode layer, thereby effectively reducing the risk of lithium plating during the charge and discharge process of the lithium-ion battery and improving the safety and cycle performance of the battery.

[0027] Furthermore, the setting of the thinning zone optimizes the material distribution, making the pressure distribution more uniform during rolling or stacking during the production of the battery cell, which is beneficial to the rolling process of battery cell production, reduces the risk of electrode damage or performance degradation due to excessive local pressure, and is conducive to improving the manufacturing yield and consistency of the battery cell.

[0028] Preferably, in an embodiment of the present invention, the laminated battery cell includes multiple negative electrode sheets, multiple positive electrode sheets, and multiple separator layers. The positive and negative electrode sheets are alternately arranged in a first direction, and a separator layer is provided between adjacent positive and negative electrode sheets. In the first direction, the first and last electrode sheets are both negative electrode sheets, i.e., the outermost layer is a negative electrode sheet. There is no limit on the number of layers in a laminated battery cell, and the number of layers can be selected based on the thickness of the battery cell.

[0029] like Figure 2 As shown, in the embodiment of the present invention, the negative electrode body 11 includes a negative current collector 111 and a negative electrode coating layer 112. In the first direction, the negative electrode coating layer 112 is provided on both sides of the negative current collector 111. A negative electrode thinning area 13 is provided on the negative electrode coating layer 112, and the negative electrode thinning area 13 is recessed into the negative electrode coating layer 112. In this way, by providing the thinning area in a specific area of ​​the negative electrode sheet, the material usage in the inactive area can be reduced, thereby reducing material costs and improving the energy density of the battery cell without sacrificing battery performance.

[0030] Preferably, in the embodiment of the present invention, the active material of the negative electrode coating layer 112 is at least one of graphite, lithium titanate and silicon carbon.

[0031] like Figure 2 As shown, in the embodiment of the present invention, the negative electrode thinned area 13 has a first surface 131, and the first surface 131 is arranged obliquely to the negative electrode coating layer 112. From the negative electrode body 11 to the direction close to the negative electrode ear 12, the distance between the first surface 131 and the negative current collector 111 gradually decreases.

[0032] In the technical scheme, the first surface 131 is arranged, so that the distribution of the active material is more uniform in the vicinity of the negative tab 12, i.e. in the area with a large current density, the risk of lithium precipitation is reduced, and the safety of the battery cell is improved.

[0033] As shown in Figure 2 and Figure 4 In the embodiment of the utility model, the included angle A1 between the first surface 131 and the negative current collector 111 is 20°-40°.

[0034] In the technical scheme, on the one hand, the reasonable selection of the inclination angle can ensure the appropriate contact area between the electrolyte and the negative material, and prevent the electrolyte from being absorbed by the negative material too quickly or too slowly, the setting of the included angle A1 can optimize the embedding path of lithium ions from the electrolyte to the negative material during charging, especially in the vicinity of the negative tab 12, the embedding efficiency of lithium ions is improved; on the other hand, the setting of the included angle A1 in the above range helps to reduce material accumulation in the area near the negative tab, avoid the problem of increased local resistance and uneven current distribution caused by excessive material thickness, thereby reducing the local thermal effect of the battery cell during charging and discharging, and improving the thermal stability of the battery cell.

[0035] As shown in Figure 2 and Figure 4 In the embodiment of the utility model, the length L1 of the first surface 131 in the second direction is 5mm-10mm.

[0036] In the technical scheme, by limiting the length of the first surface 131 in the second direction, the range of the thinning area can be accurately controlled, so as to effectively control the N / P ratio in the vicinity of the negative tab 12 to avoid lithium precipitation and improve the safety and cycle performance of the battery cell.

[0037] As shown in Figure 2 In the embodiment of the utility model, the positive main body 21 includes a positive current collector 211 and a positive coating layer 212, and the positive coating layer 212 is arranged on both sides of the positive current collector 211 in the first direction, and the positive coating layer 212 is provided with a proximal thinning area 23 and a distal thinning area 24, and at least one of the proximal thinning area 23 and the distal thinning area 24 is recessed into the positive coating layer 212. In this way, by arranging the thinning area in a specific area of the positive plate, the use of non-active area material can be reduced, thereby reducing the material cost and improving the energy density of the battery cell without sacrificing the battery performance.

[0038] Preferably, in the embodiment of the present invention, both the proximal thinned area 23 and the distal thinned area 24 are recessed into the positive electrode coating layer 212 .

[0039] Preferably, in the embodiment of the present invention, the active material of the positive electrode coating layer 212 is at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium manganese oxide, and lithium nickel manganese oxide.

[0040] like Figure 2 As shown, in an embodiment of the present invention, the proximal thinned-out region 23 has a second surface 231, which is obliquely arranged on the positive electrode coating layer 212, and the distance between the second surface 231 and the positive current collector 211 gradually decreases from the positive electrode body 21 to the direction close to the positive electrode ear 22; and / or, the distal thinned-out region 24 has a third surface 241, which is obliquely arranged on the positive electrode coating layer 212, and the distance between the third surface 241 and the positive current collector 211 gradually decreases from the positive electrode body 21 to the direction away from the positive electrode ear 22.

[0041] In the above technical solution, on the one hand, the inclined design of the second surface 231 and the third surface 241 in the proximal thinning area 23 and the distal thinning area 24 of the positive electrode sheet helps to improve the distribution of current on the positive electrode sheet. By reducing the thickness of the active material near the positive electrode ear 22 and the area far from the positive electrode ear 22, the current concentration phenomenon can be avoided, the risk of local overheating can be reduced, and the thermal stability of the battery cell can be improved; on the other hand, by setting thinning areas on both sides of the positive electrode sheet, the distribution of the positive electrode active material can be effectively controlled to ensure a good match with the negative electrode active material, thereby maintaining an N / P ratio greater than 1 in the entire battery, reducing the risk of lithium plating, and improving the safety performance of the battery cell.

[0042] like Figure 2 and Figure 4 As shown, in the embodiment of the present invention, a length L2 of at least one of the second surface 231 and the third surface 241 in the second direction is 10 mm to 15 mm.

[0043] In the above technical solution, on the one hand, by limiting the length of the first surface 131 and / or the third surface 241 in the second direction, more precise current distribution control can be achieved in the areas of the positive electrode body 21 close to and away from the positive electrode ear 22. The setting of the length L2 ensures the width of the thinning zone, which helps to control the resistance of the area and avoid local overheating caused by current concentration, thereby improving the thermal stability and safety of the battery cell; on the other hand, within the range of the length L2, the reduction in the thickness of the active material helps to maintain the N / P ratio of the entire battery cell greater than 1, reduce the risk of lithium plating, and improve the safety and cycle performance of the battery cell.

[0044] Preferably, if Figure 4As shown in the embodiment of the utility model, the length L2 of the second surface 231 and the third surface 241 in the second direction is 10mm to 15mm.

[0045] As Figure 2 shown in the embodiment of the utility model, the included angle A2 between at least one of the second surface 231 and the third surface 241 and the positive current collector 211 is 20° to 40°.

[0046] Through the above setting, by setting the included angle A2, the distribution of active material on the positive plate can be accurately controlled, and in the thinning area, the thickness of the active material is reduced, which helps to ensure that the N / P ratio of the whole battery is greater than 1, avoids the phenomenon of lithium precipitation caused by too low N / P ratio, and enhances the safety and cycle stability of the battery.

[0047] Preferably, as Figure 4 shown in the embodiment of the utility model, the included angle A2 between the second surface 231 and the positive current collector 211, and the included angle A2 between the third surface 241 and the positive current collector 211 are both 20° to 40°.

[0048] As Figure 1 and Figure 2 shown in the embodiment of the utility model, along the second direction, the laminated battery has a first side and a second side arranged oppositely, the negative tab 12 is located on the first side, and the positive tab 22 is located on the second side, and the first direction and the second direction are arranged at an included angle.

[0049] Through the above setting, the negative tab 12 and the positive tab 22 are arranged on the first side and the second side of the battery respectively, so as to help optimize the layout and space utilization inside the battery, reduce the length of the conductive path inside the battery, and thus reduce the internal resistance of the battery, and improve the charge and discharge efficiency of the battery.

[0050] Further, since the negative tab 12 and the positive tab 22 are respectively located on the first side and the second side of the laminated battery, the heat source can be more evenly distributed, which helps to improve the thermal stability of the battery during high-power charge and discharge, and reduces the risk of local overheating.

[0051] From the above description, it can be seen that the above-mentioned embodiments of the utility model realize the following technical effects: the thinning area is arranged on the tab side and the side away from the tab of the positive plate (namely, the side close to the positive tab of the positive main body is provided with a proximal thinning area, and the side away from the positive tab of the positive main body is provided with a distal thinning area), the thinning area is arranged on the tab side of the negative plate (namely, the side close to the negative tab of the negative main body is provided with a negative thinning area), which can ensure that the N / P ratio of the battery cell at each position is greater than 1, the N / P ratio refers to the capacity ratio of the negative material and the positive material, keeping the N / P ratio greater than 1 can solve the risk of lithium precipitation on the tab side of the negative layer of the stacked battery, effectively reduces the risk of lithium precipitation of the lithium ion battery in the charging and discharging process, and improves the safety and cycle performance of the battery.

[0052] The above only describes the preferred embodiments of the utility model and is not used to limit the utility model, and the utility model can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A jelly-roll type battery cell, characterized by, The laminated cell comprises: at least one negative electrode sheet comprising a negative electrode body (11) and a negative electrode tab (12) connected to the negative electrode body (11); at least one positive electrode sheet comprising a positive electrode body (21) and a positive electrode tab (22) connected to the positive electrode body (21), the positive electrode sheet and the negative electrode sheet being arranged alternately in a first direction; a separator layer (3) provided between the positive electrode sheet and the negative electrode sheet, the separator layer (3) being used to separate the positive electrode sheet and the negative electrode sheet; wherein one side of the negative electrode body (11) close to the negative electrode tab (12) is provided with a negative electrode thinning area (13), one side of the positive electrode body (21) close to the positive electrode tab (22) is provided with a proximal thinning area (23), and one side of the positive electrode body (21) away from the positive electrode tab (22) is provided with a distal thinning area (24).

2. The stacked cell of claim 1, wherein, The negative electrode body (11) comprises a negative current collector (111) and a negative electrode coating layer (112), both sides of the negative current collector (111) are provided with the negative electrode coating layer (112) in the first direction, the negative electrode coating layer (112) is provided with the negative electrode thinning area (13), and the negative electrode thinning area (13) is recessed in the negative electrode coating layer (112).

3. The stacked cell of claim 2, wherein, The negative electrode thinning area (13) has a first surface (131) which is obliquely arranged on the negative electrode coating layer (112), and the distance between the first surface (131) and the negative current collector (111) gradually decreases from the negative electrode body (11) to the side close to the negative electrode tab (12).

4. The stacked cell of claim 3, wherein, The included angle A1 between the first surface (131) and the negative current collector (111) is in the range of 20°-40°.

5. The stacked cell of claim 3, wherein, The length L1 of the first surface (131) in the second direction is 5mm-10mm.

6. The stacked cell of any one of claims 1 to 5, wherein, The positive electrode body (21) comprises a positive current collector (211) and a positive electrode coating layer (212), both sides of the positive current collector (211) are provided with the positive electrode coating layer (212) in the first direction, the positive electrode coating layer (212) is provided with the proximal thinning area (23) and the distal thinning area (24), and at least one of the proximal thinning area (23) and the distal thinning area (24) is recessed in the positive electrode coating layer (212).

7. The stacked cell of claim 6, wherein, The proximal thinning area (23) has a second surface (231) which is obliquely arranged on the positive electrode coating layer (212), and the distance between the second surface (231) and the positive current collector (211) gradually decreases from the positive electrode body (21) to the side close to the positive electrode tab (22); and / or, The distal thinning area (24) has a third surface (241) which is obliquely arranged on the positive electrode coating layer (212), and the distance between the third surface (241) and the positive current collector (211) gradually decreases from the positive electrode body (21) to the side away from the positive electrode tab (22).

8. The stacked cell of claim 7, wherein, A length L2 of at least one of the second surface (231) and the third surface (241) in a second direction is 10 mm to 15 mm.

9. The stacked cell of claim 7, wherein, An included angle A2 between at least one of the second surface (231) and the third surface (241) and the positive current collector (211) is 20° to 40°.

10. The stacked cell of any one of claims 1 to 5, wherein, In the second direction, the laminated battery cell has oppositely arranged first and second sides, the negative tab (12) is located on the first side, the positive tab (22) is located on the second side, and the first direction and the second direction are arranged at an included angle.

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