Battery

Abstract

A battery comprising a casing, a battery cell (10), and an insulating film (20), wherein the insulating film (20) covers a peripheral side surface of the battery cell (10), wherein the battery cell (10) is cylindrical, the battery cell (10) has a positive electrode plate (11) and a negative electrode plate (12), two ends of the insulating film (20) each form a starting end (21) and a terminal end (22) on the peripheral side surface of the battery cell (10), the terminal end (22) of the insulating film (20) extends beyond the starting end (21), thereby forming an overlap region (S) between the starting end (21) and the terminal end (22), wherein a product of a dimension (L) of the overlap region (S) along a circumferential direction of the battery cell (10), a modulus of elasticity (M) of the insulating film (20) and a cohesive force (F) of the negative electrode plate (12) is in a range of 0.1 to 2000; wherein the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell is given in millimeters (mm); the elastic modulus (M) of the insulating film (20) is given in gigapascals (GPa) and the cohesive force (F) of the negative electrode plate (12) is given in newtons per meter (N / m).

Description

Technical area

[0001] The present application relates to the field of accumulator or battery technology for novel drive technologies and relates in particular to a battery. State of the art

[0002] A battery pack is a key component of vehicles with advanced drive technology, and batteries within the battery pack are available in various shapes, such as cylindrical batteries, prismatic batteries, blade batteries, etc. In cylindrical batteries, the inner battery cell is formed by winding electrode plates and separators together, with the winding being particularly tight, especially in the inner region of the wound cell. Therefore, the electrode plates tend to deform outward during charging and discharging processes, causing the battery cell to expand. Significant expansion of the battery cell causes an increase in the internal resistance of the cylindrical battery, which results in energy loss during charging and discharging processes and a deterioration in the cycling performance of the cylindrical battery. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present application is to overcome the disadvantages of the prior art, in which cylindrical batteries have a tendency towards a re-deformation of electrode plates and a strong expansion of the battery cell during charging and discharging processes, which results in an increased internal resistance, and thereby to provide a battery.

[0004] To solve the above problem, the present application provides a battery comprising a battery cell and an insulating film, the insulating film covering a circumferential side surface of the battery cell. The battery cell includes a positive electrode plate and a negative electrode plate. The insulating film forms a starting end and a terminal end at two of its ends. On the circumferential side surface of the battery cell, the terminal end of the insulating film extends beyond the starting end, thereby forming an overlap region between the starting end and the terminal end. A product of a dimension of the overlap region along a circumferential direction of the battery cell, a Young's modulus of the insulating film, and a cohesive force of the negative electrode plate is in a range of 0.1 to 2000. This application offers the following advantages:

[0005] Using the technical solution of the present application, the insulating film covers the battery cell with an overlapping area between the starting end and the terminal end, allowing the insulating film to exert a restraining force on the battery cell. The above solution comprehensively adjusts the relationship between the dimension of the overlapping area along the circumferential direction of the battery cell, the elastic modulus of the insulating film, and the cohesive force of the negative electrode plate. It utilizes the dimension of the overlapping area of ​​the insulating film to secure the battery cell, thereby preventing expansion of the battery cell during charging and discharging processes, which would result in increased battery impedance.It also prevents excessive overlapping of the insulating film overlap area, which would cause the insulating film to exert excessive counterforce on the battery cell, resulting in indentation of the electrode plates and an increased risk of lithium plating. Furthermore, it can cause detachment of the electrode material. Furthermore, if the cohesive force of the negative electrode plate is low, the electrode plates expand more during charging and discharging, requiring a corresponding increase in the overlap area dimension to restrain the battery cell and prevent excessive expansion, which would result in increased internal resistance of the battery.However, the dimensions of the overlap area should not be too large, because this would result in the overlap area of ​​the insulating film exerting a counter-load on the electrode plates, resulting in indentation of the electrode plates and an increased risk of lithium plating. Furthermore, the risk of electrode material detachment increases. Furthermore, an excessive overlap area can be avoided by increasing the elastic modulus of the insulating film to enhance the retention effect on the battery cell. However, the elastic modulus of the insulating film should not be too high, because this would result in a greater counter-force of the insulating film on the electrode plates.Therefore, the technical solution of the present application eliminates the disadvantages of the prior art, in which cylindrical batteries have a tendency towards re-deformation of electrode plates and strong expansion of the battery cell during charging and discharging processes, which results in an increased internal resistance. Short description of the drawings

[0006] To more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings required to describe the specific embodiments or the prior art are briefly introduced below. It is understood that the drawings described below illustrate some embodiments of the present application. Those skilled in the art can create additional drawings based on these drawings without creative effort. In Fig.1 is a structural diagram of the battery of the present application; in Fig. 2 is a structural diagram of the battery cell in the battery of Fig. 1 shown; in Fig. 3 shows a diagram where the edge of the insulating film does not extend beyond the edge of the positive electrode plate in the battery cell of Fig. 2; in Fig. 4 shows a diagram in which the edge of the insulating film is located between the edges of the positive electrode plate and the negative electrode plate in the battery cell of Fig. 2 is located; in Fig. 5 shows a diagram in which the edge of the insulating film is located between the edges of the negative electrode plate and the separator in the battery cell of Fig. 2 extends; in Fig. 6 shows a diagram where the edge of the insulating film extends over the edge of the separator in the battery cell of Fig.2. Reference numbers:

[0007] 10 - battery cell; 11 - positive electrode plate (11); 12 - negative electrode plate; 13 - positive electrode tab; 14 - negative electrode tab; 15 - separator; 20 - insulating film; 21 - starting end; 22 - ending end; 30 - casing; S - overlapping area. Detailed description

[0008] The technical solutions of the present application are described clearly and completely in conjunction with the drawings. It is obvious that the described embodiments are only a part of the embodiments of the present application and not all. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0009] It should be noted that in the description of the present application, terms such as "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inside," and "outside" with respect to orientations or positional relationships are based on those shown in the drawings and are used solely for convenience of description and convenience. They do not indicate or imply that the device or element referred to has a specific orientation or must be constructed and operated in a specific orientation. Therefore, these terms should not be construed as limitations of the present application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be understood as indicating or implying a relative meaning.

[0010] It should be noted that in the description of the present application, terms such as "mounted," "connected," and "coupled" are to be understood broadly unless otherwise expressly stated and limited. For example, they may refer to permanent connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections via intermediate elements or internal communication between two elements. Those skilled in the art can understand the specific meanings of these terms in the present application based on specific situations.

[0011] Furthermore, technical features involved in various embodiments of the present disclosure described below may be combined with each other as long as they do not contradict each other.

[0012] As in the Fig. 1 and Fig. As shown in Fig. 2, one embodiment of the battery according to the present application includes a battery cell 10 and an insulating film 20 covering a circumferential side surface of the battery cell 10. The battery cell 10 includes a positive electrode plate 11 and a negative electrode plate 12, and the insulating film 20 has a starting end 21 and a terminal end 22 formed at both ends thereof. The terminal end 22 of the insulating film 20 extends beyond the starting end 21 on the circumferential side surface of the battery cell 10, thereby forming an overlapping portion S. Furthermore, a product of the dimension L of the overlapping portion S along the circumferential direction of the battery cell, the elastic modulus M of the insulating film 20, and the cohesive force F of the negative electrode plate 12 is in a range of 0.1 to 2000.

[0013] This means that the value of L*M*F is in the range of 0.1 to 2000.

[0014] Using the technical solution of this embodiment, the insulating film 20 covers the battery cell 10, and there is an overlapping area S between the starting end 21 and the terminal end 22, allowing the insulating film 20 to exert a restraining force on the battery cell 10. The technical solution of this embodiment comprehensively adjusts the relationship between the dimension L of the overlapping area S along the axial direction of the battery cell 10, the elastic modulus M of the insulating film 20, and the cohesive force F of the negative electrode plate 12. It utilizes the dimension L of the overlapping area S of the insulating film 20 to secure the battery cell 10, thereby preventing expansion of the battery cell during charging and discharging, which would result in increased battery impedance.It also prevents an excessive overlap dimension L of the overlap region S of the insulating film 20, which would cause the insulating film 20 to exert excessive counterforce on the battery cell 10, resulting in indentation of the electrode plates and an increased risk of lithium plating, and potentially causing detachment of the electrode material. Furthermore, if the cohesive force of the negative electrode plate 12 is small, the electrode plates expand more during charging and discharging, requiring a corresponding increase in the dimension L of the overlap region S to restrain the battery cell 10 and prevent excessive expansion, which would result in increased internal resistance of the battery.However, the dimension L of the overlap region S should not be too large because it would cause the overlap region S of the insulating film 20 to exert a counter-load on the electrode plates, potentially resulting in a depression of the electrode plates and an increased risk of lithium plating, and potentially increasing the risk of electrode material detachment. Furthermore, by increasing the elastic modulus M of the insulating film 20 to enhance the retaining effect on the battery cell 10, an excessive dimension of the overlap region S can be avoided, although the elastic modulus M of the insulating film 20 should not be too high because this would result in a higher counter-force of the insulating film 20 on the electrode plates.Therefore, the technical solution of this embodiment eliminates the disadvantages of the prior art, in which cylindrical batteries have a tendency towards re-deformation of electrode plates and strong expansion of the battery cell during charging and discharging processes, which results in an increased internal resistance.

[0015] It should be noted that the battery cell 10 includes a positive electrode plate 11, a negative electrode plate 12, and a separator 15, with the separator 15 being disposed between the positive electrode plate 11 and the negative electrode plate 12. The positive electrode plate 11, the negative electrode plate 12, and the separator 15 are wound or stacked, thereby forming the battery cell 10. The positive electrode plate 11 includes a positive current collector and a layer of positive active material, while the negative electrode plate 12 includes a negative current collector and a layer of negative active material. There is no restriction on the material of the positive current collector, as long as it is conductive and does not cause adverse chemical changes in the battery.Materials such as stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. Furthermore, the negative current collector can be made of copper, stainless steel, nickel, titanium, etc. In specific embodiments, the positive current collector can be aluminum and the negative current collector can be copper.

[0016] Furthermore, the battery casing may consist of a steel shell, aluminum shell, etc.; the steel shell may be stainless steel, nickel-plated steel, etc.; the aluminum shell may be an aluminum alloy, aluminum-manganese alloy, etc.

[0017] The battery also includes an electrolyte, which can be any electrolyte suitable for electrochemical energy storage devices in this field. The electrolyte includes an electrolyte salt and a solvent, with the electrolyte salt typically comprising a lithium salt.

[0018] The lithium salt includes, in particular, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and / or lithium tetrafluorooxalatophosphate (LiTFOP). The concentration of the electrolyte in the electrolyte solution can be 0.5–5 mol / l.

[0019] In particular, the solvent comprises ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), γ-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and / or diethyl sulfone (ESE).

[0020] Furthermore, the battery cell 10 of the cylindrical battery, as shown in Fig.2, the battery cell 10 has a cylindrical shape formed by winding the positive electrode plate 11, the separator 15, and the negative electrode plate 12 in this order. To maintain the shape of the battery cell 10 and ensure insulation from other structures, the outer peripheral surface of the battery cell 10 is covered with an insulating film 20 after winding. The material of the insulating film can be PP, PE, PET, PI, etc.

[0021] As in Fig. As shown in Figure 2, the insulating film 20 has a starting end 21 and a terminal end 22 along the circumferential direction of the battery cell 10. The starting end 21 refers to the end at which the insulating film 20 is started to be attached to the battery cell 10, and the terminal end 22 refers to the end at which the insulating film 20 ends.

[0022] As in Fig.2, when applying the insulating film 20, first, the starting end 21 is attached to the battery cell 10, then the insulating film is wound around the battery cell 10 for one turn; then, the insulating film 20 is extended a certain distance beyond the starting end 21; finally, the insulating film 20 is cut off (or the insulating film 20 is processed to have a predetermined size), thereby forming the terminal end 22, and is attached to the insulating film. As shown in Fig. 2, there is an overlapping area S between the terminal end 22 and the initial end 21 (the area provided with an X-pattern in Fig. 2), because the terminal end 22 extends beyond the initial end 21. Due to this overlap area S, the insulating film 20 as a whole exerts a retaining force on the battery cell 10.

[0023] Furthermore, the recovery of the electrode plate is smaller when the cohesive force F of the negative electrode plate 12 is higher, which is why the elastic modulus of the insulating film 20 can be suitably reduced.

[0024] Furthermore, the recovery of the electrode plate is larger when the cohesive force F of the negative electrode plate 12 is smaller, which is why the elastic modulus M of the insulating film 20 should be appropriately increased in order to prevent excessive expansion of the battery cell 10.

[0025] By comprehensively adjusting the relationship between the length of the overlapping area S, the elastic modulus M of the insulating film 20, and the cohesive force F of the negative electrode plate 12, the dimension of the overlapping area S of the insulating film 20 in this embodiment is used to secure the battery cell 10, thereby preventing expansion of the battery cell during charging and discharging operations, which would result in increased battery impedance. Furthermore, this prevents depression of the electrode plates caused by the overlapping area S of the insulating film 20, which would increase the risk of lithium plating and the risk of electrode material peeling.

[0026] Furthermore, if the cohesive force of the negative electrode plate 12 is lower, the electrode plates expand more during charging and discharging processes, requiring a corresponding increase in the dimension L to restrain the battery cell 10 and prevent excessive expansion, which would result in increased internal resistance of the battery. However, the dimension L should not be too large because an excessive dimension L would cause the overlapping area S of the insulating film 20 to exert a counter-load on the electrode plates, which could result in indentation of the electrode plates and an increased risk of electrode material detachment.

[0027] Furthermore, the need for an excessive dimension L can be avoided by increasing the elastic modulus M of the insulating film 20 to enhance the restraining effect on the battery cell 10. However, the elastic modulus M of the insulating film 20 should not be too high, because an excessive elastic modulus M would also cause a higher counterforce on the electrode plates. Therefore, the relationship between the cohesive force F of the electrode plates, the dimension L of the overlap region S, and the elastic modulus M of the insulating film 20 (i.e., the product of these three parameters) must be comprehensively controlled.

[0028] Therefore, in this embodiment, the value of L*M*F is in the range of 0.1 to 2000. Optionally, the value of L*M*F may take any value of 0.1, 0.5, 1, 100, 500, 1000, 2000, or any value between any two of these values. More preferably, the value of L*M*F is in the range of 1 to 600. Where appropriate, the value of L*M*F may take any value of 1, 5, 10, 50, 100, 500, or 600, or any value between any two of these values. In particular, the battery can achieve lower internal resistance (DCR) and reduced risk of electrode material detachment by further controlling L*M*F within the range of 1 to 600.

[0029] Furthermore, the unit of cohesive force F of the negative electrode plate is 12 N / m, the unit of elastic modulus M of the insulating film is 20 GPa, and the unit of dimension L of the overlap area is S mm.

[0030] The method for manufacturing the battery in this embodiment is described below: 1. Manufacturing a positive electrode plate 11

[0031] The positive active material LiNi x Co y Mn zO2 (where x + y + z = 1) or lithium iron phosphate, the conductive agent acetylene black, and the binder PVDF are mixed in a weight ratio of 96:2:2, the solvent NMP is added, and stirring is carried out in a vacuum mixer until the system is uniform, thereby obtaining a positive electrode slurry. The positive electrode slurry is applied to both surfaces of the aluminum foil of the positive current collector, dried at room temperature, then transferred to an oven for further drying, then cold-pressed and cut, thereby obtaining the positive electrode plate 11.

[0032] Table 1 lists the specific selection of LiNixCoyMnzO2 positive active materials and the silicon contents in the negative active materials for eighteen samples in this application, comprising sixteen embodiments and two comparative examples. Table 1: Compositions of positive active materials and negative electrode materials of the embodiments and comparative examples sample Positive active material Silicon content in the negative active material Embodiment 1 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 2 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 3 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 4 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 5 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 6 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 7 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 8 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 9 LiNi 0,6 Co 0,3 Mr 0,1 O2 5% Embodiment 10 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 11 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 12 LiNi 0,6 Co 0,3 Mr 0,1 O2 5% Embodiment 13 Lithium iron phosphate / Embodiment 14 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 15 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Embodiment 16 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Comparison example 1 LiNi 0,9 Co 0,05 Mr 0,05 O2 5% Comparison example 2 LiNi 0,9 Co 0,05 Mr 0,05 O2 5%

[0033] For example, in embodiment one, x = 0.9, y = 0.05, z = 0.05, thus x + y + z = 1.

[0034] For example, in embodiment nine, x = 0.6, y = 0.3, z = 0.1, thus x + y + z = 1. 2. Manufacturing a negative electrode plate 12

[0035] The negative active material, artificial graphite, or a mixture of artificial graphite and a silicon-based material, is mixed at a weight ratio ranging from 1.25% to 20%. The conductive agent (SP) and binder (SBR and / or PAA) are mixed at specific weight ratios, deionized water is added as a solvent, and stirring is carried out in a vacuum mixer until the system is uniform, thereby obtaining a negative electrode slurry. The negative electrode slurry is evenly applied (according to the requirements of each embodiment and each comparative example in Table 2) to both surfaces of the copper foil of the negative current collector, dried at room temperature, and then transferred to a furnace for further drying. It is then cold-pressed and cut to obtain the negative electrode plate 12. Table 2: Binder components and cohesive force of the negative electrode plates in the embodiments and comparative examples sample Binder components Cohesive force of the negative electrode plate Embodiment 1 1.8% SBR + 1.2% PAA 14 Embodiment 2 2.6% SBR + 0.4% PAA 6 Embodiment 3 2.3% SBR + 0.7% PAA 7,5 Embodiment 4 1.4% SBR + 1.6% PAA 10 Embodiment 5 0.5% SBR + 2.5% PAA 20 Embodiment 6 2.5% SBR + 0.5% PAA 6,5 Embodiment 7 0.7% SBR + 2.3% PAA 16 Embodiment 8 2.8% SBR + 0.2% PAA 4 Embodiment 9 3% SBR 2,5 Embodiment 10 3% PAA 30 Embodiment 11 1.4% SBR + 1.6% PAA 10 Embodiment 12 2.5% SBR 1,5 Embodiment 13 2% SBR 1,2 Embodiment 14 SBR: PAA = 2% SBR + 2% PAA 40 Embodiment 15 SBR: PAA = 2.2% SBR + 0.8% PAA 8 Embodiment 16 SBR: PAA = 0.8% SBR +2.2%PAA 15 Comparison example 1 2.6% SBR 1,6 Comparison example 2 1.5% SBR + 2.5% PAA 42

[0036] Furthermore, the range of weight ratios of conductive agent, binder SBR and binder PAA is: (92% - 96%):(0% - 4%):(2% - 4%).

[0037] It should be noted that the cohesive force of the negative electrode plate 12 can be adjusted by varying the components and ratios of the binder. Table 2 shows the cohesive force of the negative electrode plate 12 for different components and ratios of SBR and PAA in the binder.

[0038] For example, in embodiment one, the weight fraction of SBR in the negative active material is 1.8%, the weight fraction of PAA is 1.2%, thus the total binder weight fraction in the negative active material is 3%.

[0039] For example, in embodiment nine, the weight fraction of SBR in the negative active material is 3%, so the total binder weight fraction in the negative active material is 3% (i.e., PAA is not included).

[0040] For example, in embodiment ten, the weight fraction of PAA in the negative active material is 3%, so the total binder weight fraction in the negative active material is 3% (i.e., SBR is not included).

[0041] It should be noted that in this application, the method for adjusting the cohesive force F of the negative electrode plate 12 is not limited. For example, the cohesive force F of the negative electrode plate 12 can be adjusted by the binder formula. 3. Production of electrolyte

[0042] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, FEC is added according to the embodiments and comparative examples, then the thoroughly dried lithium salt LiPF6 is dissolved in the organic solvent mixture to prepare an electrolyte with a lithium salt concentration of 1 mol / L. 4. Production of Separator 15

[0043] In this embodiment, a polyethylene film is selected as a separator and cut to size, thereby forming the separator 15. 5. Manufacturing a lithium-ion battery

[0044] The above positive electrode plate 11, the separator 15 and the negative electrode plate 12 are stacked in this order, with the separator 15 being located between the positive electrode plate 11 and the negative electrode plate 12 for insulation, then this is wound up, whereby the bare battery cell 10 is obtained;

[0045] The battery cell 10 covered with the insulating film 20 is placed in the outer packaging shell or the packaging outer casing (casing 30), dried, and electrolyte is injected, then proceeds to vacuum packaging, standing, formation according to the formation method, molding and other processes of the embodiments and comparative examples, thereby obtaining the lithium ion battery.

[0046] Furthermore, this application does not impose any restrictions on the testing method for the cohesive force F of the negative electrode plate 12. Here, the cohesive force F can be tested, for example, using the following method: First, the cohesive force F of the negative electrode plate 12 in this embodiment refers to the adhesive force between negative active particles in the negative active coating layer. The method includes the following: 1. A standard steel plate (50 mm x 125 mm) is used as a rigid test base plate, the surface of the steel plate is cleaned with lint-free paper dipped in alcohol, one side of a 50 mm x 125 mm 3M double-sided tape is attached to the steel plate, ensuring a flat, wrinkle-free adhesion; 2. The negative electrode plate 12 with active coating is cut into test samples of 50 mm x 125 mm; 3. The test electrode plate is attached to the other adhesive surface of the double-sided tape, then another layer of double-sided tape is attached to the surface of the electrode plate, ensuring a flat, wrinkle-free contact during bonding; 4. After rolling with a pressure roller, a universal testing machine is used to clamp one end of the steel plate and one end of the 3M tape, the stroke of the tensile testing machine is set to 100 mm, the tensile test is carried out at a speed of 300 mm / min, the stroke of the tensile testing machine is set to 100 mm, it is recorded when the curve of the tensile testing machine software becomes flatter and the deflection exceeds 80 mm, the machine is stopped, and then the average tensile force value from the flat part of the curve is read as the cohesive force.

[0047] Furthermore, this application does not limit the testing method for the elastic modulus M of the insulating film 20. For example, the elastic modulus M can be tested using a static tensile test method according to the national standard GB22315-2008. The testing method includes the following: The test specimen is attached to the tensile testing machine, a gradually increasing tensile force is applied, and the deformation of the test specimen is measured; The elastic modulus is calculated based on the tensile strain relationship.

[0048] Furthermore, this application does not impose any restrictions on the elastic modulus M of the insulating film 20. For example, the elastic modulus M can be adjusted by changing the material of the insulating film 20 and selecting an insulating film 20 obtained under different processing conditions.

[0049] Furthermore, the test method for the dimension L of the overlap region S in this embodiment may, for example, comprise the following: A flexible ruler is used to measure along the circumferential direction of the battery cell 10, thereby obtaining the distance between the starting end 21 and the terminal end 22, or first, flexible objects such as a string are used to obtain a marking line equal to the distance between the starting end 21 and the terminal end 22, then the length of this marking line is measured with a ruler to obtain the distance between the terminal end 22 and the starting end 21.

[0050] Table 3 shows the internal resistance of the battery (DCR, unit mΩ) and conditions for the electrode plates under various values ​​of the elastic modulus M of the insulating film 20, the cohesive force F of the negative electrode plate 12, and the dimension L of the overlapping area S in the above sixteen embodiments and the two comparative examples. First, a detailed explanation of the consideration of various values ​​of the elastic modulus M of the insulating film 20, the cohesive force F of the negative electrode plate 12, and the dimension L of the overlapping area S is given below. Table 3: Performance tests of the batteries in the embodiments and comparative examples at different values ​​of the parameters sample Cohesive force of the negative electrode plate Dimensions of the overlap area Elastic modulus of the insulating film F * M * L Battery DCR Condition of the electrode plate Embodiment 1 14 4 2 112 1,6 No anomaly Embodiment 2 6 9,8 0,3 17,64 1,8 No anomaly Embodiment 3 7,5 1 3,9 29,25 1,9 No anomaly Embodiment 4 10 0,5 0,2 1 2 No anomaly Embodiment 5 20 7,5 4 600 2,3 No anomaly Embodiment 6 6,5 0,6 0,2 0,78 3,5 No anomaly Embodiment 7 16 10 4 640 3,4 Slight depression on the electrode plate Embodiment 8 4 0,4 4 6,4 2,7 No anomaly Embodiment 9 2,5 9 0,15 3,375 2,9 No anomaly Embodiment 10 30 0,36 0,15 1,62 3,2 No anomaly Embodiment 11 10 19,5 0,8 156 3 No anomaly Embodiment 12 1,5 0,6 3,5 3,15 3,3 No anomaly Embodiment 13 1,2 0,15 5 0,9 3,4 No anomaly Embodiment 14 40 24 2 1920 3,9 Moderate depression on the electrode plate Embodiment 15 8 0,15 0,2 0,24 3,7 No anomaly Embodiment 16 15 20 3 900 3,6 No anomaly Comparison example 1 1,6 0,3 0,12 0,0576 5 No anomaly Comparison example 2 42 20 4,5 3780 3,8 Severe deepening and Occurrence of lithium plating

[0051] If necessary, the cohesive force F of the negative electrode plate 12 is in the range from 1.5 N / m to 40 N / m.

[0052] For example, the value of the cohesive force F of the negative electrode plate 12 may take any value of 1.5 N / m, 5 N / m, 10 N / m, 20 N / m, 30 N / m or 40 N / m or any value between any two of these values.

[0053] Furthermore, the cohesive force F of the negative electrode plate 12 reflects the bonding force between particles of the negative active material. With a suitable cohesive force, the negative electrode plate 12 exhibits good structural stability, which can reduce the recovery of the electrode plate during charging and discharging of the battery cell 10, thereby reducing the internal resistance of the battery.By controlling the cohesive force F of the negative electrode plate 12 within the range of 1.5 N / m - 40 N / m, too small a cohesive force is avoided, which cannot sufficiently suppress the deformation of the electrode plate, causing excessive expansion of the battery cell and increased internal resistance; furthermore, too high a cohesive force is avoided, which would require an increased binder content, which would affect lithium ion transport and electron transport, thereby causing increased internal resistance of the battery (DCR).

[0054] Preferably, the cohesive force F of the negative electrode plate 12 is in the range of 6 N / m to 20 N / m.

[0055] By further controlling the cohesive force of the negative electrode plate 12 within the preferred range of 6 - 20 N / m, a recovery of the electrode plate and an increase in the internal resistance of the battery can be further reduced.

[0056] For example, the value of the cohesive force F of the negative electrode plate 12 may take any value of 6 N / m, 8 N / m, 10 N / m, 15 N / m, 20 N / m or any value between any two of these values.

[0057] More preferably, the cohesive force F of the negative electrode plate 12 is in the range of 6 N / m to 18 N / m.

[0058] For example, the value of the cohesive force F of the negative electrode plate 12 may take any value of 6 N / m, 8 N / m, 10 N / m, 12 N / m, 15 N / m or 18 N / m or any value between any two of these values.

[0059] Optionally, the product of the dimension L of the overlap region along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 is in the range from 0.05 to 60. For example, the value of this product may take any value of 0.05, 1, 5, 10, 20, 50 or 60 or any value between any two of these values.

[0060] Furthermore, by controlling the overlap dimension L and the elastic modulus M of the insulating film 20 within a suitable range, the relationship between them can be further balanced. When the overlap dimension L is relatively large, the elastic modulus M can be correspondingly reduced to avoid an excessively strong counterforce of the insulating film 20 on the battery cell 10, which would increase the risk of electrode material peeling off; when the overlap dimension L is relatively small, the elastic modulus M can be correspondingly increased to avoid a weak restraining effect on the battery cell 10 due to an excessively small overlap dimension L, which would increase expansion of the battery cell.By controlling the product of the overlap dimension L and the elastic modulus M of the insulating film 20 between 0.05 and 60, an overly large product is avoided, which would cause the overlap dimension L and / or the elastic modulus M to be too large, which would result in a depression of the electrode plate and an increased risk of lithium plating and possibly an increased risk of detachment of electrode material; this also avoids an overly small overlap dimension L and / or an overly low elastic modulus M, which would result in a weak restraint effect on the battery cell, causing a significant expansion of the battery cell, which would increase the internal resistance of the battery.

[0061] Furthermore, the dimension L of the overlap area S along the circumferential direction of the battery is in the range of 0.15 mm to 20 mm.

[0062] In particular, by controlling the dimension L of the overlapping region of the insulating film 20 along the battery circumference within a suitable range, good expansion restraint of the battery cell 10 can be achieved, while avoiding an excessively large dimension L of the overlapping region, which causes excessive counterforce on the battery cell 10, depression of the electrode plate, and easy material detachment; moreover, an excessively large dimension L of the overlapping region would also affect the heat dissipation performance of the battery cell 10 and make expansion of the battery cell difficult; thereby also avoiding an excessively small dimension L of the overlapping region S, which would have a weak restraining effect on the battery cell 10 and prevent significant expansion of the battery cell 10.

[0063] For example, the dimension L of the overlap region S can take any value of 0.15 mm, 0.2 mm, 0.5 mm, 1 mm, 10 mm or 20 mm or any value between any two of these values.

[0064] Preferably, the dimension L of the overlap region S along the axial direction of the battery is in the range of 0.5 mm to 10 mm.

[0065] For example, the dimension L of the overlap region S can take any value of 0.5 mm, 0.6 mm, 1 mm, 5 mm, 7 mm or 10 mm or any value between any two of these values.

[0066] Furthermore, the elastic modulus M of the insulating film 20 is in the range of 0.1 GPa to 5 GPa. The elastic modulus of the insulating film 20 can be adjusted by selecting insulating films made of different materials or by manufacturing them under different manufacturing conditions. The insulating film 20 can be obtained using conventional procurement methods.

[0067] In particular, by controlling the elastic modulus M of the insulating film within a suitable range, an effective expansion restriction of the battery cell 10 can be obtained, avoiding situations in which an excessively small elastic modulus M causes the insulating film 20 to expand with the battery cell 10 without achieving a restraining effect; this also avoids situations in which an excessively high elastic modulus M causes the insulating film to exert an excessively strong counterforce on the battery cell 10 during expansion, which results in a depression of the electrode plate and possibly increases the risk of detachment of electrode material.

[0068] For example, the elastic modulus M of the insulating film 20 can take any value of 0.1 GPa, 0.5 GPa, 1 GPa, 2 GPa, 3 GPa or 5 GPa or any value between any two of these values.

[0069] Preferably, the elastic modulus M of the insulating film 20 is in the range of 0.2 GPa to 4 GPa.

[0070] For example, the elastic modulus M of the insulating film 20 can take any value of 0.1 GPa, 0.5 GPa, 1 GPa, 2 GPa, 3 GPa or 5 GPa.

[0071] As in Fig. 2, in the technical solution of this embodiment, the battery cell 10 also includes a battery cell body, a positive electrode tab 13, and a negative electrode tab 14. Both the positive electrode tab 13 and the negative electrode tab 14 extend outward along the battery cell body direction from one end of the battery cell 10, and the product of the dimension L of the overlapping area S along the circumferential direction of the battery cell 10 and the elastic modulus M of the insulating film 20 is in the range of 0.1 to 40.

[0072] In this embodiment, both the positive electrode tab 13 and the negative electrode tab 14 extend from the top of the battery cell 10, as shown in Fig. 2 is shown.

[0073] This implementation has the advantages of a shorter current transmission path and reduced battery impedance because the positive electrode tab 13 and the negative electrode tab 14 extend from the same side of the battery cell 10. However, because both tabs extend from the same side, this side of the battery cell 10 (the tab extension side) generates more heat, resulting in increased expansion of the battery cell. The product of the dimension L of the overlap area S along the circumferential direction of the battery cell 10 and the elastic modulus M of the insulating film 20 must be appropriately increased.

[0074] Optionally, the product of the dimension L of the overlap region S along the circumferential direction of the battery cell 10 and the elastic modulus M of the insulating film 20 may take any value of 0.1, 1, 5, 10, 20, 30, 40 or any value between any two of these values ​​if both the positive electrode tab 13 and the negative electrode tab 14 extend from the same side of the battery cell 10.

[0075] As in Fig.As shown in Figure 3, to ensure sufficient lithium introduction points into the negative electrode plate 12, a "negative wrapped positive" stacking mode is typically adopted, which means that the negative electrode plate 12 covers the positive electrode plate 11. Furthermore, the separator 15 covers both the positive electrode plate 11 and the negative electrode plate 12, thereby ensuring complete insulation therebetween and preventing short circuits caused by contact between their edges.

[0076] In Fig. 3, the uppermost horizontal line illustrates the edge at the axial end of the battery cell 10, which is also the edge of the separator 15.

[0077] Next, various arrangements of the edge of the insulating film 20 along the axial direction of the battery cell 10 in this embodiment will be described. Arrangement one:

[0078] As in Fig.As shown in Figure 3, the distance between the edge of the insulating film 20 along the axial direction of the battery cell 10 and the end of the battery cell 10 is greater than the distance between the edge of the positive electrode plate 11 and the end of the battery cell 10, which means that the edge of the insulating film 20 does not extend beyond the edge of the positive electrode plate 11. The dimension L of the overlap region S along the circumferential direction of the battery cell 10 is in the range of 0.6 mm to 15 mm.

[0079] In the Fig. In the arrangement shown in Figure 3, the edge of the insulating film 20 does not extend beyond the edge of the positive electrode plate 11. Therefore, the edge of the insulating film 20 also does not extend beyond the edges of the negative electrode plate 12 and the separator 15.

[0080] In particular, because the tabs (positive electrode tab 13 and / or negative electrode tab 14) extend outward from the end of the battery cell 10, more heat is generated at the end position of the battery cell 10. To prevent heat-induced damage to the insulating film 20 by the tabs, the edge of the insulating film 20 is set lower than the edge of the positive electrode plate 11. However, because the edge height of the insulating film 20 is small, the upper end of the battery cell 10 is not covered, and the upper tabs generate more heat that can be transferred downward. Therefore, in this implementation, the dimension L of the overlap region S should be increased accordingly to restrain the battery cell 10 and prevent excessive expansion, which results in increased impedance.

[0081] When the distance between the edge of the insulating film 20 and the end of the battery cell 10 is greater than the distance between the edge of the positive electrode plate 11 and the end of the battery cell 10, the value of the distance L of the overlapping region S along the circumferential direction of the battery cell 10 may optionally take any value of 0.6 mm, 0.8 mm, 1 mm, 5 mm, 10 mm or 15 mm or any value between any two of these values. Arrangement two:

[0082] As in Fig. As shown in Figure 4, the negative electrode plate 12 covers the positive electrode plate 11. The edge of the insulating film 20 is located along the axial direction of the battery cell 10 between the edges of the negative electrode plate 12 and the positive electrode plate 11, and the dimension L of the overlapping area S along the circumferential direction of the battery cell 10 is in the range of 0.4 mm to 13 mm.

[0083] In the Fig.4, the edge of the insulating film 20 extends beyond the edge of the positive electrode plate 11, but not beyond the edge of the negative electrode plate 12, that is, the edge of the insulating film 20 is located between the edges of the positive electrode plate 11 and the edge 12 of the negative electrode plate.

[0084] Because the insulating film 20 specifically covers the positive electrode plate 11, the expansion of the positive electrode plate 11 is restricted. Therefore, the dimension L of the overlap region S can be reduced relative to the area in the first arrangement. Because a portion of the negative electrode plate 12 remains unconstrained, the dimension L of the overlap region S cannot be too small.

[0085] When the edge of the insulating film 20 is located between the edges of the negative electrode plate 12 and the positive electrode plate 11, the dimension L of the overlapping region S along the circumferential direction of the battery cell 10 may optionally take any value of 0.4 mm, 0.6 mm, 1 mm, 5 mm, 10 mm or 13 mm or any value between any two of these values. Arrangement three:

[0086] As in Fig. 5, the edge of the insulating film 20 along the axial direction of the battery cell 10 is located between the edges of the negative electrode plate 12 and the separator 15, and the dimension L of the overlapping area S along the circumferential direction of the battery cell is in the range of 0.2 mm to 12 mm.

[0087] In the Fig.5, the edge of the insulating film 20 extends beyond the edge of the negative electrode plate 12, but not beyond the edge of the separator 15, that is, the edge of the insulating film 20 is located between the edges of the negative electrode plate 12 and the separator 15.

[0088] In particular, because the insulating film 20 covers the negative electrode plate 12, the insulating film 20 can achieve a better restraining effect with respect to the battery cell 10 along the axial direction of the battery cell 10, whereby the dimension L of the overlapping region S can be further suitably reduced compared to arrangement two.

[0089] When the edge of the insulating film 20 is located between the edges of the negative electrode plate 12 and the separator 15, the dimension L of the overlapping region S along the circumferential direction of the battery cell may optionally take any value of 0.2 mm, 0.5 mm, 1 mm, 5 mm, 10 mm or 12 mm or any value between any two of these values. Arrangement four:

[0090] As in Fig. 6, the edge of the insulating film 20 along the axial direction of the battery cell 10 is flush with the edge of the separator 15, or the edge of the insulating film 20 extends beyond the edge of the separator 15 and is folded over onto the end face of the battery cell. In this case, the dimension L of the overlap region S along the circumferential direction of the battery cell 10 is in the range of 0.5 mm to 10 mm.

[0091] At the Fig.6, the edge of the insulating film 20 along the axial direction of the battery cell 10 may be flush with the edge of the separator 15, which means that the insulating film 20 completely covers the positive electrode plate 11, the negative electrode plate 12, and the separator 15. Furthermore, the edge of the insulating film 20 may also be processed to extend beyond the edge of the separator 15, and during battery cell processing, the portion of the edge of the insulating film 20 that extends beyond the separator 15 is folded inward and adhered to the end surface of the battery cell 10. With this arrangement, the effect of the insulating film 20 completely covering the positive electrode plate 11, the negative electrode plate 12, and the separator 15 can also be achieved.

[0092] In particular, those skilled in the art will appreciate that the separator 15 itself has pores that can be used to transfer heat and gas. In arrangement four, the edge of the insulating film 20 extends beyond the edge of the separator 15, meaning that the insulating film 20 also covers the separator 15. This arrangement is not conducive to heat dissipation through the pores of the separator 15. Since gas cannot escape, increased expansion of the battery cell results, requiring the area of ​​dimension L of the overlap region S to be increased accordingly.

[0093] When the edge of the insulating film 20 is flush with the edge of the separator 15 or when the edge of the insulating film 20 extends beyond the edge of the separator 15 and is folded over onto the end face of the battery cell 10, the dimension L of the overlap region S along the circumferential direction of the battery cell 10 may optionally take any value of 0.5 mm, 1 mm, 3 mm, 5 mm or 10 mm or any value between any two of these values.

[0094] As in the Fig. 1 and Fig. As shown in Figure 2, the battery in the technical solution of this embodiment also includes a casing 30, and the outer profile of the casing 30 is cylindrical. The product of the dimension L of the overlapping area S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 is in the range of 0.1 to 38.

[0095] In particular, when the casing 30 is cylindrical, a small gap exists between the outer surface of the battery cell 10 and the inner surface of the casing 30 because the battery cell 10 is also cylindrical. With the smaller gap between the cylindrical battery cell 10 and the cylindrical casing 30, a greater restriction on the expansion of the battery cell 10 is required, so the product of the dimension L of the overlap area S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 must be increased accordingly.

[0096] If the outer profile of the housing 30 is cylindrical, the product of the dimension L of the overlap region S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 can optionally take any value from 0.1, 0.5, 1, 5, 10, 20, 30, 38, or any value between any two of these values. In some embodiments not shown, the outer profile of the housing 30 can also have the shape of a hexagonal prism. In this embodiment, the product of the dimension L of the overlap region S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 is in the range of 0.08 to 30.

[0097] In particular, when the casing 50 has the shape of a hexagonal prism and the battery cell 10 is cylindrical, there is relatively more space between the casing 50 and the battery cell 10 (especially at the intersection points of the edges), which allows a larger expansion space for the battery cell 10, and therefore the product of the dimension L of the overlapping area S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 can be reduced accordingly.

[0098] When the outer profile of the casing 30 has the shape of a hexagonal prism, the product of the dimension L of the overlapping region S along the circumferential direction of the battery cell and the elastic modulus M of the insulating film 20 can optionally take any value from 0.08, 0.1, 0.5, 1, 5, 10, 20, or 30, or any value between any two of these values. In the technical solution of this embodiment, the ratio between the dimension L of the overlapping region S along the circumferential direction of the battery cell and the diameter of the battery cell 10 is in the range of 0.006 to 0.4.

[0099] The larger the diameter of the battery cell 10, the greater the expansion during charging and discharging. As the diameter of the battery cell 10 increases, the increased load on the inner battery cell 10, in particular, results in more difficult expansion, which requires a corresponding increase in the dimension L of the overlap area S.

[0100] Conversely, if the battery cell 10 is smaller, the dimension L of the overlap area S can be reduced accordingly.

[0101] The ratio between the dimension L of the overlap region S along the circumferential direction of the battery cell and the diameter of the battery cell 10 may, if appropriate, take any value of 0.006, 0.01, 0.05, 0.1, 0.2 or 0.4 or any value between any two of these values.

[0102] Furthermore, in this embodiment, the negative electrode plate 12 comprises graphite, and the cohesive force F of the negative electrode plate 12 is in the range of 1.5 N / m to 20 N / m.

[0103] Optionally, the cohesive force F of the negative electrode plate 12 may take any value of 1.5 N / m, 5 N / m, 10 N / m, 15 N / m or 20 N / m or any value between any two of these values.

[0104] Furthermore, the negative electrode plate 12 comprises a silicon-based material, and the cohesive force F of the negative electrode plate 12 is in the range of 2.5 N / m to 30 N / m.

[0105] In particular, when the negative electrode plate 12 comprises a silicon-based material, the silicon-containing negative electrode plate 12 expands more. To prevent excessive electrode expansion, the silicon-based system requires a higher cohesive force.

[0106] When the negative electrode plate 12 comprises a silicon-based material, the cohesive force F of the negative electrode plate 12 may optionally take any value of 2.5 N / m, 5 N / m, 10 N / m, 20 N / m, 25 N / m or 30 N / m or any value between any two of these values.

[0107] Furthermore, the positive electrode plate 11 includes a positive active material comprising a ternary nickel-cobalt-manganese material. Based on the total molar amount of transition metal elements other than lithium in the positive active material, the molar content ratio of the nickel element is greater than or equal to 0.7, and the dimension L of the overlap region S along the circumferential direction of the battery cell is in the range of 0.3 mm to 20 mm.

[0108] In particular, the higher the nickel content of the positive electrode plate 11, the more heat is generated during charging and discharging of the battery, which results in increased expansion, whereby the dimension L of the overlap area S must be larger.

[0109] Based on the total molar amount of transition metal elements other than lithium in the positive active material, the molar content ratio of the nickel element may be 0.7, 0.8, 0.9, etc., as appropriate, and the dimension L of the overlap region S along the circumferential direction of the battery cell 10 may take any value of 0.3 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, or 20 mm.

[0110] Below, Tables 1 to 3 are combined to introduce the test results for the battery internal resistance (DCR, unit mΩ) and conditions for the electrode plates, that is, the battery performance, at various values ​​of the elastic modulus M of the insulating film 20, the cohesive force F of the negative electrode plate 12, and the dimension L of the overlapping area S in sixteen embodiments and two comparative examples.

[0111] From Embodiments one to sixteen and Comparative Examples one and two, it is apparent that when the product of the elastic modulus M of the insulating film 20, the cohesive force F of the negative electrode plate 12, and the dimension L of the overlapping portion S (the value of L*M*F) is in the range of 0.1-2000, the battery has a lower internal resistance (DCR), whereby the performance of the batteries of the embodiments is superior to that of the batteries of the Comparative Examples.

[0112] In comparative example one, where the cohesive force F of the negative electrode plate 12 is too small and both the overlap dimension L of the overlap region S and the elastic modulus M are small (that is, the value of L*M*F is too small, less than 0.1), the insulating film 20 cannot sufficiently restrain the battery cell 10, thereby causing increased expansion of the battery cell and significantly increased internal resistance of the battery, DCR (reaching a peak value of 5).

[0113] In Comparative Example 2, where the cohesive force F of the negative electrode plate 12 is too high and both the overlap dimension L of the overlap region S and the elastic modulus M of the insulating film 20 are too large (i.e., the value of L*M*F is too large, greater than 2000), although the battery cell 10 can be well restrained, a high counterforce is exerted on the electrode plates due to an excessive elastic modulus M and an excessive overlap dimension L, resulting in severe indentation and an increased risk of lithium plating. (The term "indentation" refers to dimples formed in the corresponding regions of the electrode plates.)

[0114] In batteries of the first to fifth embodiments, the elastic modulus M of the insulating film 20, the cohesive force F of the negative electrode plate 12, and the dimension L of the overlap region S, as well as their product, are all within the preferred ranges (with the cohesive force F of the negative electrode plate 12 being within a more preferred range in the first to fourth embodiments). Therefore, the internal resistance DCR of the battery remains low, and the electrode plates have no recess or the recess size is controlled within 10 μm. Both cases where the electrode plates have no recesses and where the thickness difference between recessed regions and other regions is controlled within 10 μm are uniformly categorized as "No."

[0115] In embodiments six and seven, the three parameters—elastic modulus M of the insulating film 20, cohesive force F of the negative electrode plate 12, and dimension L of the overlap region S—are within the preferred intervals, but the value of L*M*F is not within the preferred range. Therefore, the internal resistance of the battery, DCR, shows a slight increase compared to embodiments one to five, but still remains at a low level. Furthermore, in embodiment seven, a slightly larger dimension L of the overlap region S and a slightly higher elastic modulus M of the insulating film 20 cause a slight depression in the electrode plates corresponding to the overlap region of the insulating film.

[0116] In embodiments eight to twelve, at least some of the three parameters—elastic modulus M of the insulating film 20, cohesive force F of the negative electrode plate 12, and the dimension L of the overlap region S—are not within the preferred intervals, but the value of L*M*F is within the preferred range. Therefore, the internal resistance of the battery, DCR, shows a slight increase compared to embodiments one to five.

[0117] From Embodiment Fourteen, it is apparent that although the cohesive force F of the negative electrode plate 12, the dimension of the overlapping portion S, and the elastic modulus M of the insulating film 20 satisfy the formula range, a relatively high cohesive force F of the negative electrode plate 12 and a relatively large dimension L of the overlapping portion S result in a higher DCR of the battery and a moderate depression in the electrode plates.

[0118] From the ninth and twelfth embodiments, it can be seen that in silicon-doped systems, the performance in terms of the internal resistance DCR of the battery is slightly deteriorated when the cohesive force F of the negative electrode plate 12 is lower than 2.5 N / m.

[0119] It can be seen from Embodiment Fifteen that when the nickel content in the positive electrode plate 11 is relatively high, too small an overlap dimension L of the overlap region S results in slightly inferior performance in terms of the internal resistance DCR of the battery.

[0120] Regarding the conditions for electrode plates, the specific explanations are as follows: “No”: does not illustrate any depression in electrode plates, or the thickness difference between depressed areas and other areas is less than 10 µm; “Slight depression”: illustrates that the difference in thickness between depressed areas and other areas of the electrode plates is greater than 10 µm and less than or equal to 30 µm; ‘Medium depression’: means that the difference in thickness between depressed areas and other areas of the electrode plates is greater than 30 µm and less than or equal to 50 µm; “Deep depression”: indicates that the thickness difference between depressed areas and other areas of the electrode plates is greater than 50 µm.

[0121] Furthermore, the test procedures for various parameters and battery performance are introduced in Table 3. I. Test method for the cohesive force F of the negative electrode plate 12: 1. A bare negative electrode plate is used, soaked in a dimethyl carbonate (DMC) solution for 4 hours at room temperature, then air-dried after soaking; 2. A standard steel plate (50 mm x 125 mm) is used as a rigid test base plate, the surface of the steel plate is cleaned with lint-free paper dipped in alcohol, one side of a 50 mm x 125 mm 3M double-sided tape is attached to the steel plate, ensuring a flat, wrinkle-free adhesion; 3. The negative electrode plate 12 with active coating is cut into test samples of 50 mm x 125 mm; 4. The test electrode plate is attached to the other adhesive surface of the double-sided tape, then another layer of double-sided tape is attached to the surface of the electrode plate, ensuring a flat, wrinkle-free contact during bonding; 5. After rolling with a pressure roller, the clamps of a universal testing machine are used to hold one end of the steel plate and the other end of the 3M tape. The stroke of the tensile testing machine is set to 100 mm. The tensile test is carried out at a speed of 300 mm / min. The stroke of the tensile testing machine is set to 100 mm. When the curve in the tensile testing machine software becomes flatter and the deflection exceeds 80 mm, the machine is stopped. Then, the average tensile force value from the flat portion of the curve is read as the cohesive force. II. Elastic modulus tests: 1. An empty battery cell is used, with the insulating film separated from the battery cell; 2. The test specimen is attached to the tensile testing machine, a gradually increasing tensile force is applied, and the deformation of the test specimen is measured; 3. The elastic modulus is calculated based on the tensile strain relationship. III. Battery internal resistance (DCR) tests: 1. The battery is placed in a temperature chamber at 25 °C until thermal equilibrium is reached; 2. It is charged with a constant current of 1 / 3 C up to the upper voltage limit (3.65 V for LiFePO4, 4.25 V for LiNixCoyMnzO2) at constant voltage until the current is less than 0.05 C, more than 3 cycles are performed, the battery capacity C1 is recorded; 3. It is left to rest for 5 minutes; 4. It is discharged at a rate of 1 / 3 C to adjust the battery to an SOC of 80%; 5. It is discharged for 18 s at a rate of 1 C, the battery voltage U2 before completion of the discharge, the current I and the battery voltage U1 after stabilization are recorded, it is calculated according to the formula R1 = (U2 - U1) / I, whereby the DC resistance R1 is obtained, where this R1 represents the discharge DCR at 25 °C, 1 C.

[0122] In the technical solution of this application, the insulating film 20 covers the battery cell 10, and there is an overlapping area S between the starting end 21 and the terminal end 22, allowing the insulating film 20 to exert a restraining force on the battery cell 10. The technical solution of this embodiment comprehensively adjusts the relationship between the dimension L of the overlapping area S along the axial direction of the battery cell 10, the elastic modulus M of the insulating film 20, and the cohesive force F of the negative electrode plate 12. It utilizes the dimension L of the overlapping area S of the insulating film 20 to secure the battery cell 10, thereby preventing expansion of the battery cell during charging and discharging, which would result in increased battery impedance.Furthermore, it also prevents an excessive overlap dimension L of the overlap region S of the insulating film 20, which would cause the insulating film 20 to exert an excessive counterforce on the battery cell 10, resulting in indentation of the electrode plates, an increased risk of lithium plating, and possibly an increased risk of electrode material detachment. Furthermore, if the cohesive force of the negative electrode plate 12 is small, the electrode plates expand more during charging and discharging operations, requiring a corresponding increase in the dimension L of the overlap region S to restrain the battery cell 10 and prevent excessive expansion, which would result in increased internal resistance of the battery.However, the dimension L of the overlap region S should not be too large because it would cause the overlap region S of the insulating film 20 to exert a counter-load on the electrode plates, potentially resulting in a depression of the electrode plates and an increased risk of lithium plating, and potentially increasing the risk of electrode material detachment. Furthermore, by increasing the elastic modulus M of the insulating film 20 to enhance the retaining effect on the battery cell 10, an excessive dimension of the overlap region S can be avoided, although the elastic modulus M of the insulating film 20 should not be too high because this would result in a higher counter-force of the insulating film 20 on the electrode plates.Therefore, the technical solution of this embodiment eliminates the disadvantages of the prior art, in which cylindrical batteries have a tendency towards re-deformation of electrode plates and strong expansion of the battery cell during charging and discharging processes, which results in an increased internal resistance.

[0123] It should be noted that the battery cell 10 includes a positive electrode plate 11, a negative electrode plate 12, and a separator 15, with the separator 15 being disposed between the positive electrode plate 11 and the negative electrode plate 12. The positive electrode plate 11, the negative electrode plate 12, and the separator 15 are wound or stacked, thereby forming the battery cell 10. The positive electrode plate 11 includes a positive current collector and a layer of positive active material, while the negative electrode plate 12 includes a negative current collector and a layer of negative active material. There is no restriction on the material of the positive current collector, as long as it is conductive and does not cause adverse chemical changes in the battery.Materials such as stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. Furthermore, the negative current collector can be made of copper, stainless steel, nickel, titanium, etc. In specific embodiments, the positive current collector can be aluminum and the negative current collector can be copper.

[0124] Furthermore, the battery casing may consist of a steel shell, aluminum shell, etc.; the steel shell may be stainless steel, nickel-plated steel, etc.; the aluminum shell may be an aluminum alloy, aluminum-manganese alloy, etc.

[0125] The battery also includes an electrolyte, which can be any electrolyte suitable for electrochemical energy storage devices in this field. The electrolyte includes an electrolyte salt and a solvent, with the electrolyte salt typically comprising a lithium salt.

[0126] Obviously, the above embodiments are merely examples for clear illustration and do not represent limitations on the implementation methods. Other forms of modification or variation can be made by ordinary technicians in the field based on the above description. A list of all implementation methods is neither necessary nor possible here. The obvious modifications or variations derived therefrom remain within the scope of this invention. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] Standard GB22315-2008

[0047]

Claims

[1] A battery comprising a casing, a battery cell (10) and an insulating film (20), wherein the insulating film (20) covers a peripheral side surface of the battery cell (10), wherein the battery cell (10) is cylindrical, the battery cell (10) has a positive electrode plate (11) and a negative electrode plate (12), two ends of the insulating film (20) each form a starting end (21) and a terminal end (22) on the peripheral side surface of the battery cell (10), the terminal end (22) of the insulating film (20) extends beyond the starting end (21), thereby forming an overlap region (S) between the starting end (21) and the terminal end (22), wherein a product of a dimension (L) of the overlap region (S) along a circumferential direction of the battery cell (10), a modulus of elasticity (M) of the insulating film (20) and a cohesive force (F) of the negative electrode plate (12) is in a range of 0.1 to 2000; wherein the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell is given in millimeters (mm); the elastic modulus (M) of the insulating film (20) is given in gigapascals (GPa) and the cohesive force (F) of the negative electrode plate (12) is given in newtons per meter (N / m). [2] The battery according to claim 1, wherein the product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell, the elastic modulus (M) of the insulating film (20) and the cohesive force (F) of the negative electrode plate (12) is in a range of 1 to 600. [3] Battery according to one of the preceding claims, wherein the cohesive force (F) of the negative electrode plate (12) is in a range from 1.5 N / m to 40 N / m; and / or the product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) and the elastic modulus (M) of the insulating film (20) is in a range from 0.05 to 60. [4] Battery according to one of the preceding claims, wherein the battery cell (10) has a battery cell body, a positive electrode tab (13) and a negative electrode tab (14) along an axial direction of the battery cell (10), wherein the positive electrode tab (13) and the negative electrode tab (14) extend from two ends of the battery cell body, respectively, and a product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) and the elastic modulus (M) of the insulating film (20) is in a range of 0.08 to 35. [5] Battery according to one of the preceding claims, wherein the battery cell (10) further comprises a battery cell body, a positive electrode tab (13) and a negative electrode tab (14) along an axial direction of the battery cell (10), wherein both the positive electrode tab (13) and the negative electrode tab (14) extend from the same end of the battery cell body and a product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) and the elastic modulus (M) of the insulating film (20) is in a range of 0.1 to 40. [6] Battery according to one of the preceding claims, wherein along the axial direction of the battery cell (10) a distance between an edge of the insulating film (20) and an end of the battery cell (10) is greater than a distance between an edge of the positive electrode plate (11) and the end of the battery cell (10) and the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) is in a range of 0.6 mm to 15 mm. [7] Battery according to one of the preceding claims, wherein an edge of the negative electrode plate (12) extends along the axial direction of the battery cell (10) beyond an edge of the positive electrode plate (11), an edge of the insulating film (20) is located between the edge of the negative electrode plate (12) and the edge of the positive electrode plate (11), and the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) is in a range of 0.4 mm to 13 mm. [8] Battery according to one of the preceding claims, wherein the battery cell (10) further comprises a separator (15) along the axial direction of the battery cell (10), an edge of the separator (15) extends over edges of the negative electrode plate (12) and the positive electrode plate (11), an edge of the insulating film (20) is located between the edge of the negative electrode plate (12) and the edge of the separator (15), and the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell is in a range of 0.2 mm to 12 mm. [9] Battery according to one of the preceding claims, wherein the battery cell (10) further comprises a separator (15) along the axial direction of the battery cell (10), wherein an edge of the separator (15) extends beyond edges of the negative electrode plate (12) and the positive electrode plate (11), an edge of the insulating film (20) is flush with the edge of the separator (15) or the edge of the insulating film (20) extends beyond the edge of the separator (15) and is folded over onto an end face of the battery cell (10), and the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell (10) is in a range of 0.5 mm to 10 mm. [10] Battery according to one of the preceding claims, wherein the battery further comprises a housing (30), wherein an outer profile of the housing (30) has the shape of a hexagonal prism and a product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell and the elastic modulus (M) of the insulating film (20) is in a range of 0.08 to 30. [11] Battery according to one of the preceding claims, wherein the battery further comprises a housing (30), wherein an outer profile of the housing (30) is cylindrical and a product of the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell and the elastic modulus (M) of the insulating film (20) is in a range of 0.1 to 38. [12] Battery according to one of the preceding claims, wherein a ratio between the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell and a diameter of the battery cell (10) is in a range of 0.006 to 0.

4. [13] Battery according to one of the preceding claims, wherein the negative electrode plate (12) comprises graphite and the cohesive force (F) of the negative electrode plate (12) is in a range of 1.5 N / m to 20 N / m. [14] Battery according to one of the preceding claims, wherein the negative electrode plate (12) comprises a silicon-based material and the cohesive force (F) of the negative electrode plate (12) is in a range of 2.5 N / m to 30 N / m. [15] A battery according to any one of the preceding claims, wherein the positive electrode plate (11) comprises a positive electrode active material, and the positive electrode active material comprises a ternary nickel-cobalt-manganese material based on a total molar amount of transition metal elements other than lithium in the positive electrode active material, wherein a molar content ratio of the nickel element is greater than or equal to 0.7, and the dimension (L) of the overlap region (S) along the circumferential direction of the battery cell is in a range of 0.3 mm to 20 mm. [16] Battery according to one of the preceding claims, wherein the positive electrode plate (11) has a positive current collector and a layer of a / the positive active material, wherein the negative electrode plate (12) has a negative current collector and a layer of a / the negative active material, wherein a material of the positive current collector comprises stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel surface-treated with carbon, nickel, titanium or silver, wherein a material of the negative current collector consists of copper, stainless steel, nickel or titanium. [17] Battery according to one of the preceding claims, wherein the battery housing consists of a steel shell, for example stainless steel or nickel-plated steel, or an aluminum shell, for example aluminum-manganese alloy. [18] A battery according to any one of the preceding claims, wherein the battery comprises an electrolyte, wherein the electrolyte comprises an electrolyte salt and a solvent, for example wherein the electrolyte salt comprises a lithium salt. [19] Battery according to one of the preceding claims, wherein a material of the insulating film (20) is PP, PE, PET or PI. [20] A vehicle comprising a battery pack with batteries according to any one of the preceding claims.

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