Battery cell and battery

Abstract

The battery cell comprises a battery cell body and a protective adhesive layer, the battery cell body comprises a bottom edge and two side edges which are oppositely arranged at intervals, and the protective adhesive layer comprises an adhesive layer and a hot melt adhesive layer which are arranged in a stacked mode. And the protective adhesive layer is at least adhered and coated on at least part of the bottom edge and at least part of the side edge through the adhesive layer. Wherein the protective glue layer is adopted to perform rubberizing protection on the edge of the battery cell body according to the mode, stress constraint is provided for the cathode and anode pieces, the problems of easy lithium precipitation on the edge and edge thickness increase caused by reduction of the contact tightness of the cathode and anode pieces in the cycle process of the battery are avoided, and the cycle life of the battery is prolonged; and meanwhile, the falling passing rate of the battery can be improved, the safety accident risks of damage, leakage, even explosion and the like caused by accidental falling of the battery are reduced, and the durability and safety of the battery are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a battery cell and a battery. Background Art

[0002] Lithium-ion batteries have outstanding advantages such as high energy density, no memory effect, long cycle life, fast charge and discharge, and less self-discharge, and are widely used in consumer electronics, electric vehicles, energy storage and other fields. Among them, the laminated lithium-ion battery has advantages such as high volume specific energy, small internal resistance, and large heat dissipation area, and has been widely concerned in various fields. However, due to the lack of stress restraint at the four peripheries of the laminated bare battery cell, as the cycle progresses, the bonding tightness of the electrode sheets at the four peripheries of the laminated lithium-ion battery decreases, resulting in phenomena such as lithium deposition at the edges, edge warping and bulging, and edge thickness thickening. On the one hand, the cycle life is reduced. On the other hand, the area where lithium is deposited and bulged at the edge may cause a short circuit, thereby posing a safety risk; moreover, the lack of stress restraint at the four peripheries of the battery cell and the decrease in the bonding tightness of the electrode sheets at the four peripheries reduce the passing rate of dropping, and the risk of safety accidents such as damage, leakage, and even explosion caused by accidental dropping of the battery increases, affecting the durability and safety of the battery. Summary of the Utility Model

[0003] The main object of the utility model is to propose a battery cell, aiming to solve the technical problems of current lithium deposition at the battery edge and low passing rate of dropping.

[0004] To achieve the above object, the utility model proposes a battery cell, including:

[0005] A battery cell body, the battery cell body includes a bottom edge and two spaced-apart and oppositely arranged side edges;

[0006] A protective glue layer, the protective glue layer includes an adhesive glue layer and a hot melt glue layer arranged in a stacked manner, and the protective glue layer is at least pasted and coated on at least part of the bottom edge and at least part of the side edges through the adhesive glue layer.

[0007] In some embodiments, the protective glue layer has at least one through hole; and / or,

[0008] The battery cell body and the protective glue layer satisfy the relationship: 1.5 ≤ (H * θ) / (100 * d) ≤ 40; where H is the thickness of the battery cell body, in μm; θ is the porosity of the protective glue layer, %; d is the pore diameter of the protective glue layer, in μm.

[0009] In some embodiments, the thickness h1 of the adhesive glue layer and the thickness h2 of the hot melt glue layer satisfy the relationship: 1 ≤ h2 / h1 ≤ 2.5.

[0010] In some embodiments, the protective glue layer satisfies at least one of the following conditions:

[0011] The porosity of the protective adhesive layer is 40% to 70%;

[0012] The aperture of the through hole is 1 μm to 10 μm;

[0013] And / or, the thickness h1 of the adhesive layer and the thickness h2 of the hot melt adhesive layer satisfy the relationship: 1 ≤ h2 / h1 ≤ 2.5, and the protective adhesive layer satisfies at least one of the following conditions:

[0014] The thickness of the protective adhesive layer is 16 μm to 25 μm;

[0015] The thickness h1 of the adhesive layer is 6 μm to 10 μm;

[0016] The thickness h2 of the hot melt adhesive layer is 10 μm to 15 μm.

[0017] In some embodiments, the protective adhesive layer includes a first adhesive layer and a second adhesive layer. Both the first adhesive layer and the second adhesive layer include an adhesive layer and a hot melt adhesive layer arranged in a stacked manner. The first adhesive layer covers at least part of the bottom edge, and the two second adhesive layers respectively cover at least part of the edges of the two side edges.

[0018] In some embodiments, the first adhesive layer completely covers the bottom edge, and the two second adhesive layers respectively completely cover the two side edges; or,

[0019] The first adhesive layer partially covers the bottom edge; or,

[0020] At least one of the second adhesive layers partially covers one of the side edges.

[0021] In some embodiments, the first adhesive layer includes at least two first sub - adhesive layers spaced on the bottom edge; or,

[0022] At least one of the second adhesive layers includes at least two second sub - adhesive layers spaced on one of the side edges.

[0023] In some embodiments, the unilateral adhesive width of the protective adhesive layer on the surface of the battery cell body perpendicular to the thickness direction is 3 mm to 6 mm; and / or, the thickness of the battery cell body is 3 mm to 6 mm.

[0024] In some embodiments, the battery cell body further includes a top edge, and the protective adhesive layer is also adhered and covered on at least part of the top edge through the adhesive layer.

[0025] The present utility model also provides a battery, which includes an electric core and a packaging film. The electric core is encapsulated in the packaging film. The electric core adopts the electric core as described above, and the hot melt adhesive layer is adhesively disposed with the packaging film.

[0026] In the electric core of the technical solution of the present utility model, it includes an electric core body and a protective adhesive layer. The electric core body includes a bottom edge and two spaced-apart and oppositely disposed side edges. The protective adhesive layer includes an adhesively bonded layer and a hot melt adhesive layer which are stacked. The protective adhesive layer is at least adhesively pasted and coated on at least part of the bottom edge and at least part of the side edge of the electric core body through the adhesively bonded layer. In this electric core, the protective adhesive layer is used to paste and protect the edges of the electric core body. Specifically, the protective adhesive layer is at least pasted on at least part of the bottom edge and at least part of the side edge of the electric core body through the adhesively bonded layer in the protective adhesive layer, providing stress restraint for the anode and cathode plates, avoiding the decrease in the contact tightness of the anode and cathode plates during the battery cycle, which may lead to problems such as easy lithium deposition at the edge and an increase in the edge thickness, improving the battery cycle life and safety; at the same time, by coating at least part of the bottom edge and at least part of the side edge of the electric core body with the protective adhesive layer, providing stress restraint for the anode and cathode plates, it can improve the battery drop passing rate, reduce the risk of safety accidents such as damage, leakage, and even explosion caused by accidental battery drop, and improve the durability and safety of the battery. Description of the Drawings

[0027] Figure 1 It is a three-dimensional structural schematic diagram of an electric core in an embodiment of the present utility model;

[0028] Figure 2 is Figure 2 the front view of the shown electric core;

[0029] Figure 3 is Figure 2 the rear view of the shown electric core;

[0030] Figure 4 is Figure 1 the structural schematic diagram of the protective adhesive layer in the shown electric core.

[0031] Explanation of the Reference Numerals in the Drawings:

[0032] Label Name Label Name 11 Adhesive layer 22 Second surface 12 Hot melt adhesive layer 23 Bottom surface 10 Protective adhesive layer 24 First side 20 Cell body 25 Second side 21 First surface

[0033] The realization, functional characteristics, and advantages of the object of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0034] Next, the solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present utility model.

[0035] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the accompanying drawings). If this specific posture changes, then the directional indication also changes accordingly.

[0036] It should also be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0037] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0038] An embodiment of the present utility model provides a battery cell. Referring to Figures 1 to 4 , the battery cell includes a battery cell body 20 and a protective glue layer 10. The battery cell body 20 includes a bottom edge and two spaced-apart and oppositely disposed side edges. The protective glue layer 10 includes an adhesive layer 11 and a hot melt adhesive layer 12 which are stacked. The protective glue layer 10 is at least adhesively coated on at least part of the bottom edge and at least part of the side edges of the battery cell body 20 through the adhesive layer 11. Furthermore, the adhesive layer 11 is adhesively bonded to the battery cell body 20, and the hot melt adhesive layer 12 is disposed on the surface of the adhesive layer 11 facing away from the battery cell body 20.

[0039] The adhesive layer 11 in the protective adhesive layer 10 can play an adhesive role at room temperature, and its melting temperature is generally higher than the formation temperature of the battery to ensure the adhesive stability during the battery manufacturing process. The melting temperature of the hot melt adhesive layer 12 is generally lower than the formation temperature of the battery, and thus can be configured to melt the hot melt adhesive layer 12 during the subsequent battery formation process to bond the packaging film of the packaged battery cell, thereby fixing the battery cell and the packaging film. The protective adhesive layer 10 can be specifically configured by sequentially arranging the adhesive layer 11 and the hot melt adhesive layer 12 at the edge of the battery cell body 20 in the above-mentioned adhesive application method during the battery cell manufacturing process to form the protective adhesive layer 10; alternatively, a composite adhesive layer including the adhesive layer 11 and the hot melt adhesive layer 12 can also be configured first, and then the protective adhesive layer 10 can be arranged at the edge of the battery cell body 20 in the above-mentioned manner using the composite adhesive layer. Among them, configuring the protective adhesive layer 10 with a composite adhesive layer including the adhesive layer 11 and the hot melt adhesive layer 12 can achieve the general normalization of adhesive tapes. Compared with the method of separating different types of adhesive tapes in conventional production, it can reduce the types of adhesive tapes in the production process, simplify materials, and reduce material costs.

[0040] In this battery cell, the protective adhesive layer is at least pasted and coated on at least part of the bottom edge and at least part of the side edge of the battery cell body through the adhesive layer 11, providing stress restraint for the anode and cathode plates, avoiding the decrease in the contact tightness of the anode and cathode plates during the battery cycle, which may lead to the problem of lithium deposition easily occurring at the edge and causing an increase in the edge thickness, and can improve the cycle life and safety of the battery; at the same time, it can improve the passing rate of battery drop, reduce the risk of safety accidents such as damage, leakage, and even explosion caused by accidental battery drop, and improve the durability and safety of the battery. Moreover, the adhesive layer 11 in the protective adhesive layer 10 is bonded and attached to the battery cell body 20, and the hot melt adhesive layer 12 is disposed on the surface of the adhesive layer 11 facing away from the battery cell body 20. When the battery cell is encapsulated with a packaging film subsequently, the hot melt adhesive layer 12 in the protective adhesive layer 10 faces the packaging film side, and during the subsequent formation process, the temperature rise can cause the hot melt adhesive layer 12 to melt and bond with the packaging film, thereby realizing the firm bonding between the battery cell body 20 and the packaging film. In addition, by arranging the protective adhesive layer at the edge of the battery cell body in the above-mentioned manner, the main area of the battery cell body generally does not need to be pasted with hot melt adhesive, which can increase the flatness of the battery and reduce the thickness loss.

[0041] Considering the electrolyte penetration and soaking in the battery manufacturing process and the liquid retention of the battery cell in the subsequent applications, in some embodiments, at least one through-hole (not shown in the figure) can be designed on the protective adhesive layer 10. Through the design of the through-hole, the penetration and soaking of the electrolyte can be enhanced, the liquid retention of the battery cell can be improved, and the possible adverse effects of the adhesive on the liquid retention can be avoided. Specifically, the through-hole can be designed to penetrate the protective adhesive layer 10 along the thickness direction of the protective adhesive layer 10, and the number, shape, arrangement, etc. of the through-holes can be designed according to needs. For example, the cross-section of the through-hole along the direction perpendicular to the thickness direction of the protective adhesive layer 10 is circular, elliptical, triangular, square, rectangular, rhombic or other polygons. In order to effectively enhance the electrolyte soaking and improve the liquid retention, the through-holes can be designed as multiple; in addition, the through-holes can be evenly arranged on the protective adhesive layer 10 to improve the uniform stability of the structure and performance; of course, in some embodiments, the through-holes can also be unevenly arranged. In addition, in some embodiments, the porosity of the protective adhesive layer 10 can be designed to be 40% - 70%; and / or, the aperture of the through-hole is 1μm - 10μm. By controlling the above porosity and / or the aperture of the through-hole, while ensuring the toughness strength of the protective adhesive layer 10, the electrolyte soaking can be enhanced, and the adverse effects of too large porosity and / or aperture on the toughness strength of the protective adhesive layer 10, affecting the edge lithium deposition and the drop safety test, as well as the problem of poor electrolyte soaking caused by too small porosity and / or aperture, resulting in the failure of the cycle diving can be avoided.

[0042] In some embodiments, the battery cell body 20 and the protective adhesive layer 10 satisfy the relationship: 1.5 ≤ (H * θ) / (100 * d) ≤ 40; where, H is the thickness of the battery cell body 20, in mm; θ is the porosity of the protective adhesive layer 10, %; d is the aperture of the protective adhesive layer 10, in μm. By controlling the above structural parameters, while ensuring the toughness strength of the protective adhesive layer 10, the electrolyte soaking after further assembling into a battery can be enhanced, the liquid retention can be improved, and thus the safety of the battery can be improved. In some embodiments, the thickness of the battery cell body 20 is 3mm - 6mm.

[0043] In some embodiments, the thickness h1 of the adhesive layer 11 and the thickness h2 of the hot-melt adhesive layer 12 in the protective adhesive layer 10 satisfy the relationship: 1 ≤ h2 / h1 ≤ 2.5, where the units of h1 and h2 are unified. For example, they can both be μm. By controlling the thicknesses of the adhesive layer 11 and the hot-melt adhesive layer 12 in the protective adhesive layer 10, while ensuring the adhesive fixing effect, the thickness can be reduced to avoid increasing the cost due to the increase in the thickness of the battery cell caused by too thick adhesive layers. Based on the above, in some embodiments, the protective adhesive layer 10 can be further controlled to meet any one of the following conditions: the thickness of the protective adhesive layer 10 is 16 μm to 25 μm; the thickness h1 of the adhesive layer 11 is 6 μm to 10 μm; the thickness h2 of the hot-melt adhesive layer 12 is 10 μm to 15 μm. Specifically, the protective adhesive layer 10 can be controlled to meet one, two, or three of the above conditions. Through the above thickness control, while ensuring the fixing effect, the pursuit of thinness and lightness of the product can be met, and the cost can be reduced.

[0044] See Figures 1 to 3 , the battery cell body 20 has a first surface 21 and a second surface 22 that are spaced apart and opposite to each other in a direction M perpendicular to the thickness direction of the battery cell body 20; in addition, it also has a bottom surface 23 and two side surfaces that are spaced apart and opposite to each other; among them, the bottom surface 23 and the two side surfaces are generally arranged along the thickness direction M. Furthermore, the bottom edge region on the battery cell body 20 generally can include the bottom surface 23 region, the edge region on the first surface 21 close to the bottom surface 23, and the edge region on the second surface 22 close to the bottom surface 23; the side edge region generally includes the side surface region, the edge region on the first surface 21 close to the side surface, and the edge region on the second surface 22 close to the side surface.

[0045] The protective adhesive layer 10 at least covers (i.e., pastes and covers) at least part of the bottom edge and at least part of the side edge of the battery cell body 20, where the covering of the bottom edge and the side edge by the protective adhesive layer 10 can both be partial covering or complete covering. Further, the protective adhesive layer 10 at least covers at least part of the bottom edge and at least part of the edges of the two side edges of the battery cell body 20. By covering at least part of the edges of the bottom edge and the two side edges of the battery cell body 20 with the protective adhesive layer 10, stronger stress restraint can be provided for the anode and cathode sheets, and the anti-drop performance of the battery can be more effectively improved, and the safety of the battery can be improved. In some embodiments, the battery cell body 20 further includes a top edge, and the top edge is spaced apart and opposite to the bottom edge. The protective adhesive layer 10 also covers at least part of the top edge through the adhesive layer 11, so as to further improve the structural stability and the battery safety. Among them, the covering of the top edge by the protective adhesive layer 10 can also be partial covering or complete covering, and generally exposes the tab. Of course, in some embodiments, the top edge of the battery cell body 20 can also be bonded with a conventional adhesive layer.

[0046] The specific arrangement of the protective adhesive layer 10 at the edge of the battery cell body 20 can be set as required. In some embodiments, the protective adhesive layer 10 includes a first adhesive layer and two second adhesive layers. Both the first adhesive layer and the second adhesive layers include an adhesive layer 11 and a hot melt adhesive layer 12 arranged in a stacked manner. The first adhesive layer covers at least a part of the bottom edge of the battery cell body 20, and the two second adhesive layers respectively cover at least a part of the two side edges. In some embodiments, the protective adhesive layer 10 may further include a third adhesive layer, which also includes an adhesive layer 11 and a hot melt adhesive layer 12 arranged in a stacked manner. The third adhesive layer covers at least a part of the top edge of the battery cell body 20.

[0047] Furthermore, the covering arrangement of each adhesive layer can be designed as required. In some embodiments, it can be designed that the first adhesive layer completely covers the bottom edge, and the two second adhesive layers respectively completely cover the two side edges. Through the above complete covering method, a strong stress constraint can be provided for the anode and cathode plates, improving the safety and stability of the structure.

[0048] In some embodiments, it can also be designed that the first adhesive layer partially covers the bottom edge, and / or at least one of the second adhesive layers partially covers one of the side edges.

[0049] Among them, when the first adhesive layer partially covers the bottom edge, specifically, it can be designed that the first adhesive layer includes at least two first sub - adhesive layers spaced on the bottom edge. The number of the first sub - adhesive layers can be 2, 3, 4 or multiple others. Each first sub - adhesive layer can be evenly arranged on the bottom edge or unevenly arranged; of course, it can also be designed that the first adhesive layer is a single adhesive layer and partially covers the bottom edge.

[0050] When at least one of the second adhesive layers partially covers one of the side edges, it can be designed that only one of the two second adhesive layers partially covers one of the side edges, and the other second adhesive layer completely covers the other side edge; it can also be designed that both of the two second adhesive layers partially cover the two side edges.

[0051] Furthermore, when at least one of the second adhesive layers partially covers one of the side edges, it can be designed that at least one of the second adhesive layers includes at least two second sub - adhesive layers spaced on one of the side edges. Only one of the two second adhesive layers can be designed as a structure including at least two second sub - adhesive layers, and the other second adhesive layer is a single adhesive layer and partially covers the other side edge, or the other second adhesive layer completely covers the other side edge; it can also be designed that both of the two second adhesive layers are designed as structures including at least two second sub - adhesive layers; or, it can also be designed that both of the two second adhesive layers are single adhesive layers and respectively partially cover the two side edges.

[0052] In addition, in some embodiments, the third adhesive layer can also be designed to completely cover the top edge, or the third adhesive layer includes at least two third sub - adhesive layers spaced on the top edge.

[0053] In actual production, the adhesive coating methods on the bottom edge, top edge, and two side edges of the battery cell body 20 can be selected and combined according to needs from the above methods.

[0054] The protection adhesive layer 10 generally wraps the battery cell body 20 by winding and pasting around the edges. Specifically, for the wrapping of a certain edge of the battery cell body 20, it generally winds from the edge area of the first surface 21 close to this edge (or the surface of this edge) through the surface of this edge and extends to the edge area of the second surface 22 close to this edge (or the surface of this edge). Furthermore, the adhesive area of the protection adhesive layer 10 at this edge includes the adhesive area of the surface of this edge and the edge adhesive areas of the two surfaces of the battery cell body 20 perpendicular to the thickness direction M of the battery cell body 20 close to this edge (or the surface of this edge).

[0055] For example, for the adhesive at the bottom edge, it can wind from the edge area of the first surface 21 close to the bottom surface 23 of the battery cell body 20 through the bottom surface 23 and extend to the edge area of the second surface 22 close to the bottom surface 23. Furthermore, the adhesive area of the protection adhesive layer 10 at the bottom edge includes the adhesive area of the bottom surface 23, the edge adhesive area on the first surface 21 close to the bottom surface 23, and the edge adhesive area on the second surface 22 close to the bottom surface 23. The two side surfaces of the battery cell body 20 that are spaced opposite to each other specifically include the first side surface 24 and the second side surface 25 that are spaced opposite to each other. Furthermore, the two side edges of the battery cell body 20 that are spaced opposite to each other include the first side edge corresponding to one side of the first side surface 24 and the second side edge corresponding to one side of the second side surface 25. For the adhesive at the first side edge, it can wind from the edge area of the first surface 21 close to the first side surface 24 through the first side surface 24 and extend to the edge area of the second surface 22 close to the first side surface 24. Furthermore, the adhesive area of the protection adhesive layer 10 at the first side edge includes the adhesive area of the first side surface 24, the edge adhesive area on the first surface 21 close to the first side surface 24, and the edge adhesive area on the second surface 22 close to the first side surface 24; for the adhesive at the second side edge, it can wind from the edge area of the first surface 21 close to the second side surface 25 through the second side surface 25 and extend to the edge area of the second surface 22 close to the second side surface 25. Furthermore, the adhesive area of the protection adhesive layer 10 at the second side edge includes the adhesive area of the second side surface 25, the edge adhesive area on the first surface 21 close to the second side surface 25, and the edge adhesive area on the second surface 22 close to the second side surface 25.

[0056] In some embodiments, the unilateral adhesive width W of the protection adhesive layer 10 on the two surfaces of the battery cell body 20 perpendicular to the thickness direction M of the battery cell body 20 can be controlled to be 3 mm to 6 mm. By controlling the adhesive width, the bonding area is ensured, the bonding stability is improved, and the passing rate of the drop test is increased.

[0057] The battery cell body 20 generally includes a positive electrode plate, a negative electrode plate, and a separator. The separator is clamped between the positive electrode plate and the negative electrode plate. The positive electrode material on the positive electrode plate can be selected from one or more of lithium cobaltate, ternary materials, and other lithium-rich positive electrode materials. The separator can be one or more of a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, and their multi-layer composite films.

[0058] An embodiment of the present invention also provides a battery. The battery includes a battery cell and a packaging film. The battery cell is encapsulated in the packaging film. The battery cell uses the battery cell described in the foregoing embodiment. The hot melt adhesive layer 12 on the protective adhesive layer 10 in the battery cell is adhesively provided with the packaging film. The specific structure of the battery cell refers to the above embodiment. Since this battery adopts all the technical solutions of the above embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0059] Among them, the adhesion between the hot melt adhesive layer 12 and the packaging film can be achieved by the melting of the hot melt adhesive layer 12 due to the increase in temperature during the battery formation process, thereby bonding the packaging film. Thus, through the setting of the protective adhesive layer 10, the fixed connection between the battery cell and the packaging film is realized, and the safety of the battery structure is improved.

[0060] The battery generally further includes an electrolyte. The electrolyte includes an electrolyte salt and an organic solvent. Among them, the specific types and compositions of the electrolyte salt and the organic solvent are not specifically limited. The electrolyte may also include a positive electrode film-forming additive, a negative electrode film-forming additive, and a low-temperature additive for improving the cycle.

[0061] During the research process, the inventors conducted a large number of research experiments, especially on the influence of the structural parameters of the protective adhesive layer (including the thickness control of the adhesive layer and the hot melt adhesive layer, the porosity and pore size control of the protective adhesive layer) on the battery performance. In the specific experimental process, battery cell protective adhesives with different structural parameters were made, applied to the edge of the battery cell for pasting protection to form a protective adhesive layer, and then finished lithium-ion batteries were made, and then the performance of the product batteries was verified. Some experimental methods, cases, and battery performance test results are listed as follows:

[0062] (I) Fabrication of the battery

[0063] The fabrication of the battery includes the following steps:

[0064] Fabrication of the battery cell protective adhesive: Different battery cell protective adhesives are prepared using a hot melt adhesive and an adhesive according to the structural parameters in Table 1. The battery cell protective adhesive is a composite adhesive, including an adhesive layer and a hot melt adhesive layer arranged in a stacked manner.

[0065] Fabrication of the cathode electrode: The cathode active material LiCoO2, conductive agent acetylene black, conductive carbon nanotubes, and binder polyvinylidene fluoride (PVDF) are uniformly dispersed in an N-methylpyrrolidone solvent system at a weight ratio of 97.6:0.5:0.6:1.3 and then coated onto the current collector, followed by cold pressing and slitting to obtain the cathode electrode.

[0066] Fabrication of the anode electrode: The anode active material, conductive agent (a mixture of SP and CNT with a mass ratio of 0.45:0.05), and binder (a mixture of SBR and PAALi with a mass ratio of 0.5:1.8) are mixed in a weight ratio of 97.7:1.1:1.2 to prepare an anode active material slurry, which is uniformly coated onto the current collector, followed by cold pressing and slitting to obtain the anode electrode.

[0067] Separator: A ceramic mixture is coated on the surface of PE to serve as the separator.

[0068] Preparation of the electrolyte: Ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) are mixed in a volume ratio of 1.2:1:4:4. Then, the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare the electrolyte.

[0069] Assembly and fabrication of the battery: The above-mentioned cathode electrode, separator, and anode electrode are stacked to fabricate the cell body. Specifically, referring to the structural parameters in Table 1, the edge of the cell body is pasted and coated with the cell protection glue prepared above to form a protection glue layer. The pasting and coating method refers to Figure 2 , and the bottom edge and the opposite side edges of the cell body are completely coated, and at the same time, the edge area between the top tabs is pasted and coated. The unilateral pasting width of the cell protection glue on the surface of the cell body perpendicular to the thickness direction is 5 mm. Then, the cell body is encapsulated with a packaging film and the electrolyte is injected to produce the finished lithium-ion battery.

[0070] According to the above method, referring to the structural parameters in Table 1, different finished lithium-ion batteries are fabricated and used as examples.

[0071] In addition, according to a battery manufacturing method similar to the above, the production of the above cell protective glue is cancelled and the bonding protection of the cell body edge using the above cell protective glue is cancelled. Conventional gluing is performed on the cell body. Specifically, two green glues are adhesively pasted at intervals on the bottom edge of the cell body. At the same time, one green glue is adhesively pasted at the top edge between the tabs to restrain the positions of the anode and cathode sheets and avoid misalignment affecting lithium deposition. In addition, two hot melt glues are respectively arranged at intervals on the two surfaces of the cell body perpendicular to the thickness direction, so as to paste and fix the cell body and the packaging film by melting during subsequent formation, avoiding the risk of short circuit caused by shaking. Then, a lithium-ion battery is assembled and prepared according to the above method, which is used as a comparative example.

[0072] (II) Performance testing

[0073] Cycling test method: At 25 °C, the cycling test is carried out according to the following method. Charging regime: Constant current charging at 3.6C until 4.25V, then constant current charging at 2.8C until 4.35V, then constant voltage charging until 1.8C, constant current charging at 1.8C until 4.4V, then constant voltage charging until 1.5C, constant current charging at 1.5C until 4.5V, constant voltage charging until 1.2V, constant current charging at 1.2C until 4.55V, and then constant voltage charging until 0.26; Discharging regime: Constant current discharging at 0.7C to 3.0V.

[0074] Capacity retention rate after 500 cycles: According to the above cycling method, the capacity retention rate after 500 cycles = discharge capacity in the 500th cycle / discharge capacity in the 1st cycle * 100%;

[0075] Liquid retention test: After the battery is manufactured, in order to allow the electrolyte to fully infiltrate the battery electrodes, an excessive amount of electrolyte is injected (the mass of the injected electrolyte is the injection volume). After formation, the excess electrolyte is pumped out (the mass of the pumped-out electrolyte is the liquid loss), and then the amount of electrolyte remaining inside the battery is the liquid retention, that is, liquid retention = injection volume - liquid loss;

[0076] Drop test: Constant current and constant voltage charging at 0.5C until 4.53V, cut-off rate 0.02C. The battery is placed in a fixture, and the test chamber is flipped at a height of 1m, 12 revolutions / min, 50 circles, a total of 100 times. The appearance and function are checked every 10 times. If the battery does not explode, catch fire, or leak liquid, the drop test is passed.

[0077] Table 1 Structural parameters of each example and comparative example

[0078]

[0079] Table 2 Performance test results of lithium-ion batteries of each example and comparative example

[0080]

[0081] From the comparison of the structural parameters and battery performance test results of the above Examples 1-9 and Comparative Example 1, it can be seen that in Examples 1-7, a protective adhesive layer with a relatively high porosity is provided, which has good electrolyte penetration ability. When providing strong stress restraint to the edges of the electrodes on the cell body, it can also ensure the liquid retention of the cell, meet the requirements of long cycles, improve the problem of lithium plating at the edges of the electrodes, and avoid edge thickness swelling. In Examples 1-7, the edges of the cell body are pasted and protected through the protective adhesive layer, which can increase the bonding area between the cell body and the packaging film, further strengthen the fixation of the cell, improve the passing rate of the drop test, and increase the safety factor of the battery. In addition, compared with the conventional adhesive pasting method in Comparative Example 1, in Example 9, the cell protective adhesive composed of a bonding adhesive layer and a hot melt adhesive layer is used to paste the edges of the cell body to form a protective adhesive layer, which can strengthen the fixation between the cell body and the packaging film and improve the passing rate of the drop test. However, since the relationship between the thickness h1 of the bonding adhesive layer and the thickness h2 of the hot melt adhesive layer in Example 9 does not satisfy 1≤h2 / h1≤2.5, the improvement of the passing rate of the drop test of the battery is limited compared with other examples where the relationship between h1 and h2 satisfies the above relationship. In Example 8, the cell protective adhesive composed of a bonding adhesive layer and a hot melt adhesive layer is used to paste the edges of the cell body to form a protective adhesive layer, which can strengthen the fixation between the cell body and the packaging film and improve the passing rate of the drop test; however, due to the fact that the structural characteristics of the protective adhesive layer in Example 8 do not satisfy the relationship 1.5≤(H*θ) / (100*d)≤40, the electrolyte penetration ability is affected, the liquid retention performance of the cell is reduced, and the cycle performance declines.

[0082] The above are only partial or preferred embodiments of the present invention. Whether in terms of text or drawings, the scope of protection of the present invention cannot be limited thereby. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the overall concept of the present invention, or any direct / indirect application in other related technical fields is included in the scope of protection of the present invention.

Claims

1. A battery cell, characterized in that, Comprising: A cell body, the cell body including a bottom edge and two relatively spaced side edges; A protective adhesive layer, the protective adhesive layer including an adhesive layer and a hot melt adhesive layer stacked, and the protective adhesive layer is at least pasted and coated on at least part of the bottom edge and at least part of the side edge through the adhesive layer.

2. The cell according to claim 1, characterized in that, There is at least one through hole in the protective adhesive layer; and / or, The cell body and the protective adhesive layer satisfy the relational expression: 1.5 ≤ (H * θ) / (100 * d) ≤ 40; where H is the thickness of the cell body in μm; θ is the porosity of the protective adhesive layer in %; d is the pore diameter of the protective adhesive layer in μm.

3. The battery cell according to claim 2, wherein, The thickness h1 of the adhesive layer and the thickness h2 of the hot melt adhesive layer satisfy the relational expression: 1 ≤ h2 / h1 ≤ 2.

5.

4. The battery cell according to claim 2, wherein The protective adhesive layer satisfies at least one of the following conditions: The porosity of the protective adhesive layer is 40% - 70%; The pore diameter of the through hole is 1 μm - 10 μm; And / or, the thickness h1 of the adhesive layer and the thickness h2 of the hot melt adhesive layer satisfy the relational expression: 1 ≤ h2 / h1 ≤ 2.5, and the protective adhesive layer satisfies at least one of the following conditions: The thickness of the protective adhesive layer is 16 μm - 25 μm; The thickness h1 of the adhesive layer is 6 μm - 10 μm; The thickness h2 of the hot melt adhesive layer is 10 μm - 15 μm.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The protective adhesive layer includes a first adhesive layer and two second adhesive layers, the first adhesive layer and the second adhesive layer both include an adhesive layer and a hot melt adhesive layer stacked, the first adhesive layer is coated on at least part of the bottom edge, and the two second adhesive layers are respectively coated on at least part of the edges of the two side edges.

6. The battery cell according to claim 5, wherein, The first adhesive layer completely coats the bottom edge, and the two second adhesive layers respectively completely coat the two side edges; or, The first adhesive layer partially coats the bottom edge; or, At least one of the second adhesive layers partially coats one of the side edges.

7. The cell according to claim 6, wherein The first adhesive layer includes at least two first sub - adhesive layers spaced on the bottom edge; or, At least one of the second adhesive layers includes at least two second sub - adhesive layers spaced on one of the side edges.

8. The battery cell according to claim 5, characterized in that, The single - side adhesive width of the protective adhesive layer on the surface of the cell body perpendicular to the thickness direction is 3 mm - 6 mm; and / or, the thickness of the cell body is 3 mm - 6 mm.

9. The battery cell according to any one of claims 1 to 4, characterized in that, The cell body further includes a top edge, and the protective adhesive layer is also pasted and coated on at least part of the top edge through the adhesive layer.

10. A battery, characterized in that, Comprising a cell and a packaging film, the cell is encapsulated in the packaging film, the cell adopts the cell according to any one of claims 1 to 9, and the hot melt adhesive layer is adhesively arranged with the packaging film.

Images