Battery cell, battery device and power-consuming device

Abstract

Battery cell comprising: a positive electrode plate, a negative electrode plate and a packaging bag, wherein the positive electrode plate and the negative electrode plate are contained within the packaging bag, wherein the positive electrode plate comprises a positive electrode current collector, a positive electrode film layer and an insulating layer, wherein the positive electrode current collector comprises a positive electrode body and a positive pole flag projecting from the positive electrode body in a first direction, wherein the positive electrode body comprises a coating region and a transition region, wherein in the first direction the transition region is located at at least one end of the coating region, wherein the positive electrode film layer is arranged on at least one surface of the coating region, and wherein the insulating layer has a first section arranged on at least one surface of the transition region. wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein an edge of the negative electrode film layer extends in the first direction beyond an edge of the first section near the positive pole flag; wherein A chamfer is provided at the junction between a first edge and a second edge of the negative electrode plate, wherein the first edge runs in the first direction and the second edge runs in a second direction, both the first direction and the second direction being perpendicular to the thickness direction of the negative electrode plate. wherein the negative electrode film layer comprises a negative electrode active material comprising graphite, wherein a volume-averaged particle size Dv50 of the graphite is 8 µm to 20 µm.

Description

Cross-reference to related registrations

[0001] This application claims priority over Chinese patent application No. 202510901332.5, filed on July 1, 2025, entitled "Battery cell, battery device and power-consuming device", the entire contents of which are hereby incorporated by reference. Technical field

[0002] The present application relates to the field of batteries, in particular a battery cell, a battery device and a power-consuming device. State of the art

[0003] The new energy sector is enjoying increasing popularity. Battery technology is a crucial factor in the development of this new energy sector.

[0004] Many design factors must be considered when developing battery technology, such as energy density, cycle performance, lifespan, capacity, fast-charging capability, and reliability. Developing a battery cell with high reliability and good cycle performance is a technical challenge that urgently needs to be addressed. Summary

[0005] The present application addresses the aforementioned problems and aims to provide a battery unit that has both high capacity and good cycle performance.

[0006] The present application relates to a battery unit, a battery device, a power-consuming device and an energy storage device.

[0007] In a first aspect, a battery cell is provided comprising: a positive electrode plate, a negative electrode plate, and a packaging bag, wherein the positive electrode plate and the negative electrode plate are contained in the packaging bag; the positive electrode plate comprises a positive electrode current collector, a positive electrode film layer, and an insulating layer; the positive electrode current collector comprises a positive electrode body and a positive terminal flag projecting from the positive electrode body in a first direction; the positive electrode body comprises a coating area and a transition area, with the transition area located at at least one end of the coating area in the first direction; the positive electrode film layer is arranged on at least one surface of the coating area;the insulating layer comprises a first section arranged on at least one surface of the transition region; the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein in the first direction the edge of the negative electrode film layer extends beyond the edge of the first section near the positive pole flag;wherein a chamfer is provided at the junction between a first edge and a second edge of the negative electrode plate, the first edge extending in the first direction and the second edge extending in a second direction, both the first and second directions being perpendicular to the thickness direction of the negative electrode plate. The negative electrode film layer comprises a negative electrode active material comprising graphite, and the volume-averaged particle size Dv50 of the graphite is 8 µm to 20 µm.

[0008] In the embodiments of the present application, a chamfer at the junction between the first and second edges of the negative electrode plate reduces the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate. Furthermore, the overhang of the edge of the negative electrode film layer beyond the edge of the first section of the insulating layer near the positive electrode terminal further reduces the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the positive electrode plate, thus eliminating the need for a chamfer on the positive electrode plate.By adjusting the volume-averaged particle size Dv50 of the graphite to between 8 µm and 20 µm, a smaller particle size is achieved, which facilitates the insertion and removal of lithium ions and improves their transport rate. This can compensate for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and thus improve the cycle performance of the battery cell. Therefore, the embodiments of this application can simultaneously improve both the reliability and the cycle performance of the battery cells.

[0009] In some embodiments, the volume-averaged particle size Dv50 of the graphite lies between 10 µm and 15 µm. This increases the transport rate of the lithium ions, thereby compensating for the problem of lithium plating caused by the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and improving the cycle performance of the battery cell.

[0010] In some embodiments, the volumetric particle size distribution Dv90 of the graphite lies between 15 µm and 40 µm.

[0011] If the volumetric particle size distribution Dv90 of the graphite is greater than or equal to 15 µm, the risk of undesirable side reactions that occur with excessively small graphite particles decreases; less lithium is consumed, and the cycle performance of the battery cell increases. If the volumetric particle size distribution Dv90 of the graphite is less than or equal to 40 µm, the lithium ions have a suitable insertion / removal distance, which facilitates lithium ion transport; this also compensates for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, further improving the cycle performance of the battery cell.

[0012] In some embodiments, the volume-averaged particle size Dv90 of the graphite lies between 18 µm and 25 µm. This gives the graphite a suitable particle size distribution, which is advantageous for reducing side reactions and lithium ion consumption, as well as improving lithium ion transport and reducing the risk of lithium plating, thereby giving the battery cell better cycle performance.

[0013] In some embodiments, the dimension of the first section in the first direction is between 1 mm and 3 mm.

[0014] If the dimension of the first section in the first direction is at least 1 mm, the insulating layer can effectively shield burrs. This reduces the risk of burrs on the positive electrode touching the negative electrode plate or damaging the separator film, thus increasing the reliability of the battery cell. If the dimension of the first section in the first direction is a maximum of 3 mm, this improves the energy density of the battery cell.

[0015] In some embodiments, the average thickness of the insulating layer is between 10 µm and 50 µm.

[0016] With an average insulating layer thickness of at least 10 µm, the insulating layer can effectively shield against burrs. This reduces the risk of burrs on the positive electrode touching the negative electrode plate or damaging the separator film, thus increasing the reliability of the battery cell. If the average insulating layer thickness is a maximum of 50 µm, this improves the energy density of the battery cell.

[0017] In some embodiments, the area in which the edge of the negative electrode film layer extends beyond the edge of the first section near the positive pole flag in the first direction has a dimension of 0.5 mm to 3 mm.

[0018] If the area where the edge of the negative electrode film layer extends beyond the edge of the first section near the positive terminal in the first direction is greater than or equal to 0.5 mm, this facilitates chamfer production and simplifies the manufacturing of the negative electrode plate. If the area where the edge of the negative electrode film layer extends beyond the edge of the first section near the positive terminal in the first direction is less than or equal to 3 mm, the risk of lithium plating is reduced, thus improving the cycle performance of the battery cell.

[0019] In some embodiments, the chamfer dimension in the first direction is smaller than the dimension of the area where the edge of the negative electrode film layer extends beyond the edge of the first section near the positive terminal in the first direction. This facilitates the chamfer's production, which in turn helps to reduce the risk of electrolyte leakage damage due to the pressure exerted on the packaging bag by the negative electrode plate.

[0020] In some embodiments, the chamfer dimension in the first direction is between 0.5 mm and 1.5 mm. If the chamfer dimension in the first direction is greater than or equal to 0.5 mm, this helps to reduce the risk of electrolyte leakage damage due to the pressure exerted on the packaging bag by the negative electrode plate. If the chamfer dimension in the first direction is less than or equal to 1.5 mm, this contributes to an improvement in the energy density of the battery cell.

[0021] In some embodiments, the dimension of the chamfer in the second direction is larger than the dimension of the chamfer in the first direction.

[0022] If the sealing position of the battery cell's packaging bag runs parallel to the second direction, the edge of the packaging bag in this direction is subjected to higher pressure than the edge in the first direction. A chamfer whose dimension in the second direction is larger than that in the first direction reduces the risk of damage to the electrolyte leakage caused by the pressure exerted on the packaging bag by the negative electrode plate.

[0023] In some embodiments, the dimension of the chamfer in the second direction is between 0.5 mm and 3 mm.

[0024] If the chamfer dimension in the first direction is greater than or equal to 0.5 mm, this helps to reduce the risk of damage to the electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate; if the chamfer dimension in the second direction is less than or equal to 3 mm, the chamfer can be easily machined, thereby reducing its manufacturing complexity and production costs.

[0025] In some embodiments, the chamfer has a rounded structure. This helps to further reduce the risk of damage from electrolyte leakage due to pressure exerted on the packaging bag, thus improving the reliability of the battery cells.

[0026] In some embodiments, the rounded structure is concave. This helps to further reduce the risk of damage from electrolyte leakage due to pressure exerted on the packaging bag, thus improving the reliability of the battery cells.

[0027] In some embodiments, the insulating layer further comprises a second section that is connected to the first section and arranged on at least one surface of a portion of the positive terminal. This helps to further improve protection against burrs, resulting in higher reliability of the battery cell.

[0028] In some embodiments, the negative electrode plate has a negative terminal, with the negative and positive terminals positioned opposite each other in the first direction. This structure allows for the production of a battery cell with larger longitudinal dimensions.

[0029] In some embodiments, the battery cell comprises an electrode arrangement including the positive electrode plate and the negative electrode plate. The packaging bag comprises two packaging films, with the electrode arrangement located between the two packaging films, the edges of which are joined to form a sealing section. The battery cell further comprises electrode terminals that extend between the two packaging films and are electrically connected to the electrode arrangement.

[0030] The battery cell with this structure is a pouch cell. The bonding of the two packaging films creates a sealed space inside the battery cell, which houses the positive electrode plate, the negative electrode plate, and the electrolyte. The electrical connection of the electrode terminals to the electrode assembly allows for easy current extraction.

[0031] In some embodiments, the packaging film comprises an insulating protective layer, a metal layer, and an insulating bonding layer, wherein the insulating bonding layer is arranged on the surface of the metal layer facing the electrode assembly, and the insulating protective layer is arranged on the surface of the metal layer facing away from the electrode assembly. In this way, the electrode assembly and the electrolyte can be sealed for protection while simultaneously retaining a degree of flexibility to provide damping in the event of compression or vibration of the battery cell.

[0032] In some embodiments, the battery cell further comprises an electrolyte with an ionic conductivity of 8.5 mS / cm to 20 mS / cm. Adjusting the electrolyte's ionic conductivity to 8.5 mS / cm to 20 mS / cm increases the lithium ion transport rate. This compensates for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and improves the battery cell's cycle performance.

[0033] In some embodiments, the ionic conductivity of the electrolyte at room temperature is between 12 mS / cm and 16 mS / cm.

[0034] An electrolyte ionic conductivity of at least 12 mS / cm improves the transport rate of lithium ions, reduces the risk of lithium plating, and leads to better cycle performance of the battery cell. Conversely, an electrolyte ionic conductivity of no more than 16 mS / cm reduces the risk of excessive gas formation in the battery cell. This reduces the influence of gas formation on lithium ion transport, which in turn lowers the risk of lithium plating and also contributes to better cycle performance of the battery cell.

[0035] In some embodiments, the electrolyte comprises a solvent consisting of a linear carbonate and / or a linear carboxylate. The aforementioned solvent has a low viscosity, and the electrolyte containing this solvent also has a low viscosity, which is advantageous for lithium ion transport and thus contributes to improving the fast-charging capability of the battery cell.

[0036] In some embodiments, the linear carbonate comprises at least one of the following substances: dimethyl carbonate and ethyl methyl carbonate, and the linear carboxylate comprises at least one of the following substances: ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. The aforementioned solvent has a low viscosity, and the electrolyte containing this solvent also has a low viscosity, which is advantageous for lithium ion transport and thus contributes to improving the fast-charging capability of the battery cell.

[0037] In some embodiments, the sum of the mass contents of the linear carbonate and the linear carboxylate, relative to the total mass of the electrolyte, lies between 10% and 90%.

[0038] When the sum of the mass fractions of linear carbonate and linear carboxylate, based on the total mass of the electrolyte, is at least 10%, the electrolyte exhibits a lower viscosity, which promotes lithium ion transport and improves the fast-charging capability of the battery cell. If the sum of the mass fractions of linear carbonate and linear carboxylate, based on the total mass of the electrolyte, is less than or equal to 90%, gas formation from these compounds within the battery cell is reduced. This decreases the risk of gas accumulation between the separator film and the positive or negative electrode plates, which in turn improves the lithium plating and thus the cycle performance of the battery cell.

[0039] In some embodiments, the sum of the mass fractions of linear carbonate and linear carboxylate lies between 40% and 80%, based on the total mass of the electrolyte. This ensures that the sum of the mass fractions of linear carbonate and linear carboxylate remains within a suitable range, allowing the battery cell to achieve both good fast-charging capability and good cycle performance.

[0040] In some embodiments, the solvent further comprises a cyclic carbonate. The cyclic carbonate exhibits good dissociation capacity for lithium ions. The combination of the cyclic carbonate with at least one linear carbonate or linear carboxylate promotes lithium ion transport in the electrolyte, thereby reducing the risk of lithium plating and improving the cycle performance of the battery cell.

[0041] In some embodiments, the ratio of the electrolyte mass to the battery cell capacity is 2.8 g / Ah to 3.5 g / Ah. This ensures good wettability of both the positive and negative electrode plates, which is advantageous for lithium ion transport, thus reducing the risk of lithium plating and improving the battery cell's cycle performance.

[0042] In some embodiments, the mass ratio of the electrolyte to the capacity of the battery cell is between 3.0 g / Ah and 3.2 g / Ah. This ensures good wettability of both the positive and negative electrode plates, which is advantageous for lithium ion transport, thus reducing the risk of lithium plating and improving the cycle performance of the battery cell.

[0043] In some embodiments, the one-sided areal density of the positive electrode plate is between 0.33 g / 1540.25 mm². 2 and 0.45 g / 1540.25 mm 2 .

[0044] If the one-sided areal density of the positive electrode plate is greater than or equal to 0.33 g / 1540.25 mm² 2 This has a positive effect on the energy density of the battery cell; if the one-sided areal density of the positive electrode plate is less than or equal to 0.45 g / 1540.25 mm² 2 This has a positive effect on lithium ion transport and the fast charging capability of the battery cell.

[0045] In some embodiments, the compaction density of the positive electrode plate is in the range of 2.3 g / cm³. 3 up to 2.65 g / cm³ 3 .

[0046] With a compression density of the positive electrode plate greater than or equal to 2.3 g / cm³ 3The battery cell exhibits a high energy density. This is achieved when the density of the positive electrode plate is less than or equal to 2.65 g / cm³. 3 This facilitates lithium-ion transport, which improves the fast-charging capability of the battery cell.

[0047] In some embodiments, the compaction density of the positive electrode plate is in the range of 2.45 g / cm³. 3 up to 2.6 g / cm³ 3 This is advantageous for improving both the fast charging capability and the energy density of the battery cell.

[0048] In some embodiments, the one-sided areal density of the negative electrode plate is between 0.15 g / 1540.25 mm². 2 and 0.22 g / 1540.25 mm 2 .

[0049] With a one-sided areal density of the negative electrode plate greater than or equal to 0.15 g / 1540.25 mm² 2The energy density of the battery cell is increased. This is achieved with a one-sided areal density of the negative electrode plate of less than or equal to 0.22 g / 1540.25 mm². 2 This facilitates lithium-ion transport, which improves the fast-charging capability of the battery cell.

[0050] In some embodiments, the compaction density of the negative electrode plate is in the range of 1.3 g / cm³. 3 up to 1.52 g / cm³ 3 .

[0051] With a compression density of the negative electrode plate greater than or equal to 1.3 g / cm³ 3 The energy density of the battery cell is increased. This occurs when the compression density of the negative electrode plate is less than or equal to 1.52 g / cm³. 3 This facilitates lithium-ion transport, which improves the fast-charging capability of the battery cell.

[0052] In some embodiments, the compaction density of the negative electrode plate is in the range of 1.35 g / cm³. 3up to 1.5 g / cm³ 3 In this way, the negative electrode plate has a suitable density that makes it possible to ensure both a high energy density and good fast charging capability of the battery cell.

[0053] In some embodiments, the positive electrode film layer comprises a positive electrode active material that includes a lithium-containing phosphate. The lithium-containing phosphate exhibits good structural stability, and the lithium phosphate battery cell shows good cycle performance.

[0054] In some embodiments, the average length of the longest diameter of the primary particles of the lithium-containing phosphate lies between 300 nm and 800 nm. In this way, the deposition distance of the lithium ions has a suitable length, which has a positive effect on the performance of the battery cell.

[0055] In some embodiments, the lithium-containing phosphate comprises a lithium-containing phosphate matrix and a carbon coating that covers at least part of the surface of the lithium-containing phosphate matrix. The carbon coating contributes to improving the conductivity of the lithium-containing phosphate, thus enabling full utilization of the battery cell's capacity.

[0056] In some embodiments, the lithium-containing phosphate comprises lithium iron phosphate doped with at least one element each of aluminum, venom, and titanium. These dopants improve the conductivity and other properties of the lithium-containing phosphate, which in turn maximizes the battery cell's capacity. Furthermore, they increase the density of the positive electrode plate, which in turn increases the battery cell's energy density.

[0057] In some embodiments, the mass fraction of Al, relative to the total mass of the lithium phosphate, is between 200 ppm and 2500 ppm, the mass fraction of V between 300 ppm and 2000 ppm, and the mass fraction of Ti between 1500 ppm and 3500 ppm. The aforementioned concentrations of dopants improve the electrical conductivity and other properties of the lithium phosphate, thereby increasing the capacity efficiency of the battery cell. Furthermore, they increase the density of the positive electrode plate, which in turn increases the energy density of the battery cell.

[0058] In some embodiments, at least part of the graphite surface is coated with a layer comprising amorphous carbon. This enables the rapid embedding of lithium ions in graphite, which in turn improves the fast-charging capability of the battery cell.

[0059] In some embodiments, the coating thickness is between 100 nm and 500 nm. This gives the coating a suitable thickness that facilitates the storage and transport of lithium ions and improves the fast-charging capability of the battery cell.

[0060] In some embodiments, the graphite includes secondary particles. This facilitates lithium ion transport and improves the fast-charging capability of the battery cell.

[0061] In some embodiments, the degree of graphitization of the graphite lies between 90% and 94%. In this way, graphite with a suitable degree of graphitization is not only conducive to a suitable specific capacity of the graphite, but can also control the side reactions in the battery cell within a suitable range and thereby provide the battery cell with a suitable capacity and cycle performance.

[0062] In some embodiments, the battery cell comprises an electrolyte, the electrolyte comprises an additive, and the additive comprises at least one of the following substances: vinylene carbonate, fluoroethylene carbonate, and 1,3-propanesultone. The aforementioned additive facilitates film formation at the negative electrode, reduces side reactions at the negative electrode, and thereby improves the cycle life, kinetics, and other performance characteristics of the battery cell.

[0063] In some embodiments, the mass fraction of the additive is less than or equal to 5% based on the total mass of the electrolyte. This mass fraction of the additive improves the cycle performance, kinetics, and other performance parameters of the battery cell.

[0064] In some embodiments, the mass fraction of the additive is between 0.5% and 3% based on the total mass of the electrolyte. This suitable mass fraction of the additive improves the cycle performance, kinetics, and other performance parameters of the battery cell.

[0065] In a second aspect, a battery device is provided which includes a battery cell according to any embodiment of the first aspect.

[0066] In some embodiments, the battery device comprises a housing, a plurality of battery cells housed in the housing and stacked along a third direction, and a thermal management component, wherein each battery cell has a nominal capacity of at least 100 Ah and has a surface with a first and a second surface, the area of ​​the first surface being larger than the area of ​​the second surface, the first surfaces of the battery cells facing each other along the third direction. The thermal management component serves to regulate the temperature of the battery cells and faces the second surfaces of the battery cells along a fourth direction, the fourth direction being perpendicular to the third direction.

[0067] In this embodiment, the nominal capacity of each battery cell is at least 100 Ah. A significant amount of heat is generated during charging and discharging of the battery cell. By tailoring the thermal management component to the battery cell, its temperature can be better controlled, reducing the risk of excessive cell temperature.

[0068] In some embodiments, the battery device further comprises an adhesive bonding device arranged between the thermal management component and the battery cells, which serves to attach the battery cell to the thermal management component. This facilitates the attachment of the battery cells and the components for the thermal management component.

[0069] In some embodiments, the adhesive is directly bonded to the packaging bag. This improves the energy density of the battery unit.

[0070] In some embodiments, the battery device further comprises a receiving housing in which at least one of the several battery cells is received, the adhesive being directly bonded to a housing wall of the receiving housing. The receiving housing enables better heat dissipation from the battery cells, which helps to lower the temperature of the battery cells.

[0071] In a third aspect, a power-consuming device is provided, comprising a battery cell according to any embodiment of the first aspect or a battery device according to any embodiment of the second aspect, wherein the battery cell or the battery device is used to provide electrical energy. Brief description of the drawings

[0072] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for their application are briefly presented below. The drawings described below naturally represent only some embodiments of the present application. Skilled engineers can create further drawings based on these without additional design effort. Fig. Figure 1 shows a schematic view of a positive electrode plate according to an embodiment of the present application; Fig. Figure 2 shows a further schematic view of a positive electrode plate according to an embodiment of the present application; Fig.Figure 3 shows a schematic representation of the interaction between a positive electrode plate and a negative electrode plate according to an embodiment of the present application; Fig. Figure 4 shows a schematic view of a negative electrode plate according to an embodiment of the present application; Fig. Figure 5 shows a further schematic view of a negative electrode plate according to an embodiment of the present application; Fig. Figure 6 shows a schematic view of a battery cell according to an embodiment of the present application; Fig. 7 shows a further schematic view of a negative electrode plate according to an embodiment of the present application; Fig. Figure 8 shows a further schematic view of a negative electrode plate according to an embodiment of the present application; Fig.Figure 9 shows a schematic view of a battery cell according to an embodiment of the present application; Fig. Figure 10 shows a schematic view of a battery device according to an embodiment of the present application; Fig. Figure 11 shows a schematic representation of the interaction between the battery cells and the thermal management component according to an embodiment of the present application; Fig. Figure 12 shows a schematic representation of the interaction between the battery cells and the thermal management component according to a further embodiment of the present application; Fig. Figure 13 shows a schematic representation of a battery module according to an embodiment of the present application; Fig. Figure 14 shows a schematic representation of a vehicle according to an embodiment of the present application. Explanation of reference symbols:

[0073] 1: Vehicle; 3: Battery cell; 5: Positive electrode plate; 50: Positive electrode current collector; 501: Positive electrode body; 502: Positive terminal tab; 5011: Coating area; 5012: Transition area; 51: Positive electrode film layer; 52: Insulating layer; 521: First section; 522: Second section; 6: Negative electrode plate; 60: Negative electrode current collector; 601: Negative electrode body; 602: Negative terminal tab; 61: Negative electrode film layer; 611: First edge; 612: Second edge; 62: Chamfer; 10: Battery device; 30: Regulator; 40: Motor; 11: Housing; 111: First housing part; 112: Second housing part; 31: Packaging bag; 33: Electrode assembly; 310: Packaging film; 321: Electrode connection; 301: First surface; 302: Second surface; 91: Thermal management component; 92: Mounting adhesive; 80: Battery module; 801: Receptacle housing; 8011: First wall; 8012: Second wall; 8013: Third wall. Detailed embodiments

[0074] The following sections describe in detail embodiments of a battery unit, a battery device, and a power-consuming device specifically disclosed in the present application, with reference, where appropriate, to the drawings. For example, a detailed description of known facts and a repeated description of essentially the same structure may be omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding by the person skilled in the art. Furthermore, the drawings and the following description serve to enable the person skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0075] The “ranges” disclosed in this application are defined in the form of lower and upper limits. A specific range is defined by selecting a lower and an upper limit. The selected lower and upper limits define the boundaries of the respective range. The range thus defined can include or exclude the end values ​​and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also considered. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, all of the following ranges are considered: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.In this application, unless otherwise specified, a range of numbers “a to b” represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the range of numbers “0 to 5” means that all real numbers between “0 to 5” have been listed in this article, and “0 to 5” is simply an abbreviation for these combinations of numbers. Furthermore, if a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0076] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form a new technical solution.

[0077] Unless otherwise stated, all technical features and optional technical features of the present application may be combined to form a new technical solution.

[0078] Unless otherwise stated, all steps of the present application may be carried out successively or in any order, but preferably consecutively. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out consecutively, or that the method may include steps (b) and (a) carried out consecutively. For example, this means that the method may also include step (c), that step (c) may be added in any order, and the method may, for example, include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0079] The battery unit provided in this application has a high capacity and good cycle performance. In a pouch cell, the cell's packaging pouch serves to hold the positive electrode, the negative electrode, the electrolyte, etc. During use and transport of battery cells, the packaging pouches can be subjected to crushing, impacts, etc., which can cause them to tear. Consequently, there is a high risk of electrolyte leakage from the packaging pouch, which impairs the reliability of the battery cells.

[0080] The embodiments of the present application provide a battery cell comprising: a positive electrode plate, a negative electrode plate, and a packaging bag for receiving the positive electrode plate and the negative electrode plate; the positive electrode plate comprises a positive electrode current collector, a positive electrode film layer, and an insulating layer; the positive electrode current collector comprises a positive electrode body and a positive terminal tab projecting from the positive electrode body in a first direction; the positive electrode body comprises a coating area and a transition area, the transition area being located at at least one end of the coating area in the first direction; the positive electrode film layer is arranged on at least one surface of the coating area;the insulating layer comprises a first section arranged on at least one surface of the transition region; the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein in the first direction the edge of the negative electrode film layer extends beyond the edge of the first section near the positive pole flag;wherein a chamfer is provided at the junction between a first edge and a second edge of the negative electrode plate, the first edge extending in the first direction and the second edge extending in a second direction, both the first and second directions being perpendicular to the thickness direction of the negative electrode plate. The negative electrode film layer comprises a negative electrode active material comprising graphite, wherein the volume-averaged particle size Dv50 of the graphite is 8 µm to 20 µm.

[0081] In the embodiments of the present application, a chamfer at the junction between the first and second edges of the negative electrode plate reduces the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate. Furthermore, the overhang of the edge of the negative electrode film layer beyond the edge of the first section of the insulating layer near the positive electrode terminal further reduces the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the positive electrode plate, thus eliminating the need for a chamfer on the positive electrode plate. This eliminates the need to chamfer both the positive and negative electrode plates simultaneously, thereby reducing manufacturing costs.

[0082] By adjusting the volume-averaged particle size Dv50 of the graphite to between 8 µm and 20 µm, the transport rate of the lithium ions is improved, thus compensating for the "reservoir" effect caused by the protruding edge of the negative electrode film layer over the edge of the positive electrode film layer and the edge of the first section of the insulating layer, which would otherwise lead to lithium plating; this sustainably improves the cycle performance of the battery cell. Therefore, the embodiments of this application can take into account both the reliability and the cycle performance of the battery cell.

[0083] The "reservoir" effect can be explained as follows. The area where the edge of the negative electrode film layer extends beyond the edge of the positive electrode film layer and the edge of the first section of the insulating layer can be called the superimposed area, and the area where the negative and positive electrode film layers overlap can be called the main area of ​​the negative electrode film layer. However, the presence of the superimposed area can lead to a "reservoir" effect, which in turn increases the risk of lithium plating and adversely affects the reliability of the battery cell. Since the amount of lithium stored in the superimposed area is lower than in the main area of ​​the negative electrode film layer, a potential difference exists between these two areas. Lithium ions from the main area migrate spontaneously into the superimposed area.As the charging and discharging cycle progresses, the lithium concentration in the supernatant region increases continuously. After several charge-discharge cycles, when a single battery cell is discharged again, all lithium ions in the main region of the negative electrode film layer are released, but not all lithium ions in the supernatant region. The lithium ion concentration in the supernatant region is higher than in the main region of the negative electrode film layer. Lithium ions from the supernatant region migrate to the interface between the negative electrode film layer and the supernatant region, leading to an increase in the lithium ion concentration at this interface. During recharging, this increases the risk of lithium plating at the interface.

[0084] In the embodiments of the present application, the battery cell can be a secondary battery which can be used continuously by activating active materials through charging after discharging.

[0085] The battery cell could be a lithium-ion battery.

[0086] During the charging process of a single battery cell, lithium ions are released from the positive electrode active material, migrate to the negative electrode and are stored there; during the discharging process, lithium ions are released from the negative electrode, migrate to the positive electrode active material and are stored there.

[0087] It is to be understood that the ‘deposition’ described in this application refers to the process in which lithium ions are deposited into the positive electrode active material or the negative electrode active material as a result of an electrochemical reaction, and that the ‘deposition’ described in this application refers to the process in which lithium ions are extracted from the positive electrode active material or the negative electrode active material as a result of an electrochemical reaction.

[0088] A typical battery cell consists of a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. The battery cell and its components as described in this application are described below. [Battery cell]

[0089] A first aspect of the present application relates to a battery cell comprising a positive electrode plate, a negative electrode plate and a packaging bag.

[0090] Fig. Figure 1 shows a schematic view of a positive electrode plate according to an embodiment of the present application. Fig. Figure 2 shows a further schematic view of a positive electrode plate according to an embodiment of the present application. As in the Fig. 1 and Fig. As shown in Figure 2, the positive electrode plate 5 comprises a positive electrode current collector 50, a positive electrode film layer 51 and an insulating layer 52.

[0091] The positive electrode current collector 50 comprises a positive electrode body 501 and a positive pole flag 502, which projects out of the positive electrode body 501 in a first direction. The first direction can be the x-direction in Fig. 1 and Fig. 2 be.

[0092] The positive electrode body 501 comprises a coating region 5011 and a transition region 5012. Along the first direction, the transition region 5012 is located at at least one end of the coating region 5011. The positive electrode film layer 51 is arranged on at least one surface of the coating region 5011, and the insulating layer 52 comprises a first section 521 which is arranged on at least one surface of the transition region 5012.

[0093] For example, along the first direction at both ends of the coating area 5011, the transition area 5012 is provided, and the insulating layer 52 is provided on at least one surface of the transition area 5012.

[0094] As a further example, along the first direction only the end of the coating area 5011 closest to the positive polar flag 502 is assigned the transition area 5012, on at least one surface of which the insulating layer 52 is provided.

[0095] Fig. Figure 3 is a schematic representation of the interaction between a positive electrode plate and a negative electrode plate according to an embodiment of the present application. Fig. Figure 4 is a schematic view of a negative electrode plate according to an embodiment of the present application. Fig. 5 is another schematic view of a negative electrode plate according to an embodiment of the present application. As in Fig.As shown in Figures 3 to 5, the negative electrode plate 6 comprises a negative electrode current collector 60 and a negative electrode film layer 61, which is arranged on at least one surface of the negative electrode current collector 60. The edge of the negative electrode film layer 61 projects beyond the edge of the first section 521 near the positive pole flag. A chamfer 62 is located at the junction between the first edge 611 and the second edge 612 of the negative electrode plate 6. The first edge 611 extends in the first direction, and the second edge 612 in a second direction. The second direction is perpendicular to the first direction and to the thickness direction of the negative electrode plate 6.

[0096] For example, in the first direction, the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521.

[0097] As a further example, the edge of the negative electrode film layer 61 projects beyond the edge of the first section 521 along the first direction and the second direction. The second direction can, for example, be the y-direction in Fig. 3 be.

[0098] The edge of the negative electrode film layer 61 extends beyond the edge of the first section 521. This can be understood as the projection of the negative electrode film layer 61 that covers and extends beyond the projection of the first section 521 onto the xoy plane.

[0099] For example, the negative electrode plate comprises two first edges 611 and two second edges 612, wherein the two first edges 611 are opposite each other in the second direction, the two second edges 612 are opposite each other in the first direction, and the first sides 611 and the second sides 612 are connected to each other.

[0100] A chamfer 62 is provided at the junction between the first edge 611 and the second edge 612. This chamfer 62 can be a rounded chamfer, a right-angled chamfer, or a compound chamfer. The compound chamfer can be a combination of a circular arc and a straight line.

[0101] Fig. Figure 6 is a schematic structure diagram of a battery cell according to an embodiment of the present application. As in Fig. As shown in Figure 6, the battery cell 3 comprises a packaging bag 31, and the positive electrode plate 5 and the negative electrode plate 6 are included in the packaging bag 31.

[0102] The packaging bag 31 can be made of a flexible material such as an aluminum-plastic film. If the packaging bag 31 is subjected to a force (e.g., compression), it tears and comes into contact with the negative electrode plate. This increases the risk of the packaging bag tearing at the corner of the edge of the negative electrode plate. By applying a chamfer 62 at the junction between the first edge 611 and the second edge 612 of the negative electrode plate 6, the risk of interference between the negative electrode plate 6 and the packaging bag can be reduced. This reduces the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate 6, thus increasing the reliability of the battery cell.

[0103] By extending the edge of the negative electrode film layer 61 beyond the edge of the first section 521 of the insulating layer 52 near the positive terminal, the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the positive electrode plate 5 is further reduced, thus eliminating the need for a chamfer on the positive electrode plate 5. This ensures the reliability of the battery cell while simultaneously reducing its manufacturing complexity.Since the first section 521 is closer to the edge of the positive electrode plate than the positive electrode film layer 51 in the first direction, and the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 and also beyond the edge of the positive electrode film layer 51, there is more space in the negative electrode plate to accommodate lithium ions released from the positive electrode plate, which helps to reduce the risk of lithium plating.

[0104] Although the edge of the negative electrode film layer 61 extending beyond the edge of the first section 521 of the insulating layer 52 near the positive terminal helps to reduce the risk of lithium plating, the “reservoir” effect (the explanation of the “reservoir” effect is given above and is not repeated here) creates a risk of lithium plating at the boundary between the area where the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 and the area where the negative electrode film layer 61 overlaps with the positive electrode film layer 51 during the charging and discharging cycles of the battery cell, which is not conducive to further improving the cycle performance of the battery cell.

[0105] The negative electrode film layer comprises a negative electrode active material consisting of graphite, with a volume-averaged particle size Dv50 of the graphite ranging from 8 µm to 20 µm. By adjusting the volume-averaged particle size Dv50 of the graphite to between 8 µm and 20 µm, a smaller graphite particle size is achieved, which facilitates the insertion and removal of lithium ions and improves their transport rate. This can compensate for the problem of lithium plating caused by the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, thus improving the cycle performance of the battery cell.

[0106] The volume-averaged particle size Dv50 of graphite represents the particle size corresponding to a cumulative volume fraction of 50% graphite and can be determined using instruments and methods known to those skilled in the art. For example, a battery cell is disassembled to obtain a negative electrode plate. The negative electrode film layer of the negative electrode plate is scraped off to obtain the negative electrode film powder. Water is then added to the negative electrode film powder and stirred. After filtration and drying, the graphite content is determined. Subsequently, the volume-averaged particle size is determined using a laser particle size analyzer according to GB / T19077-2016, laser diffraction method. The Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK, can be used as a test instrument.

[0107] The volume-averaged particle size Dv50 of the graphite can be 8 µm, 8.2 µm, 8.5 µm, 8.8 µm, 9 µm, 9.2 µm, 9.5 µm, 10 µm, 10.2 µm, 10.5 µm, 10.8 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm or any value within the above range.

[0108] In the embodiments of the present application, the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate 6 is reduced by providing a chamfer 62 at the junction between the first edge 611 and the second edge 612 of the negative electrode plate 6. Furthermore, the risk of damage to the packaging bag and electrolyte leakage due to the pressure exerted on the packaging bag by the positive electrode plate 5 is further reduced by extending the edge of the negative electrode film layer 61 beyond the edge of the first section 521 of the insulating layer 52 near the positive electrode terminal, thus eliminating the need for a chamfer 62 on the positive electrode plate 5.By adjusting the volume-averaged particle size Dv50 of the graphite to between 8 µm and 20 µm, a smaller graphite particle size is achieved, which facilitates the insertion and removal of lithium ions and improves their transport velocity. This can compensate for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and thus improve the cycle performance of the battery cell. The measures described therefore make it possible to optimize both the reliability and the cycle performance of the battery cell simultaneously.

[0109] In some embodiments, the volume-averaged particle size Dv50 of the graphite lies between 10 µm and 15 µm. This accelerates lithium ion transport. This can compensate for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and thus improve the cycle performance of the battery cell.

[0110] In some embodiments, the volumetric particle size distribution Dv90 of the graphite lies between 15 µm and 40 µm.

[0111] The volumetric particle size distribution Dv90 of graphite is defined as the particle size at which 90% of the total volume of graphite particles is smaller than or equal to this value. The volumetric particle size distribution Dv90 of graphite can be tested using the same methods as the Dv50.

[0112] The volumetric particle size distribution Dv90 of the graphite can be 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 23 µm, 24 µm, 25 µm, 28 µm, 30 µm, 32 µm, 34 µm, 36 µm, 38 µm, 40 µm or any value within this range.

[0113] With a volumetric particle size distribution (Dv90) of graphite greater than or equal to 15 µm, the risk of side reactions triggered by excessively small graphite particles decreases; lithium ion consumption is reduced, and the cell's cycle performance increases. With a volumetric particle size distribution (Dv90) less than or equal to 40 µm, the lithium ions have a sufficiently long insertion / removal distance, which facilitates their transport. This can compensate for the problem of lithium plating, which arises from the negative electrode film layer extending beyond the positive electrode film layer and the first section of the insulating layer, and thus improve the battery cell's cycle performance.

[0114] In some embodiments, the volumetric particle size distribution Dv90 of the graphite lies between 18 µm and 25 µm. This gives the graphite a suitable particle size distribution, which is advantageous for reducing side reactions and lithium ion consumption, as well as improving lithium ion transport and reducing the risk of lithium plating, thereby giving the battery cell better cycle performance.

[0115] In some embodiments, the volume-averaged particle size Dv50 of the graphite lies between 10 µm and 15 µm, and the volumetric particle size distribution Dv90 of the graphite lies between 18 µm and 25 µm. This results in a suitable average graphite particle size with a narrow distribution of graphite particles; this can facilitate lithium ion transport and increase the cycle performance of the battery cell.

[0116] In some embodiments, the first section 521 has a dimension of 1 mm to 3 mm in the first direction.

[0117] In the first direction, the dimension D1 of the first section 521 can be 1 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm or any value within the above range.

[0118] The dimension of the first section 521 in the first direction can be used as the average dimension. For example, the length of the first section 521 in the first direction is measured at several points, and the mean value is then used as D1.

[0119] For example, the first section 521 has a rectangular shape.

[0120] Burrs typically form during the production of the positive electrode plate, for example, when cutting a positive pole tab or when dividing a large positive electrode plate into two positive electrode plates. The insulating layer 52 can play a role in preventing burrs. For example, it can reduce the risk of burrs overlapping with the negative electrode plate and the risk of burrs penetrating the separator film.

[0121] If the first section 521 has a dimension greater than or equal to 1 mm in the first direction, the insulating layer 52 acts as an effective barrier against burrs, thus reducing the risk of burrs from the positive electrode plate 5 coming into contact with the negative electrode plate 6 or penetrating the separator film; this results in high reliability for the battery cell. If the dimension of the first section 521 is less than or equal to 3 mm in the first direction, the energy density of the battery cell is simultaneously increased.

[0122] In some embodiments, the insulating layer 52 has an average thickness of 10 µm to 50 µm.

[0123] The average thickness D2 of the insulating layer 52 can be 10 µm, 15 µm, 20 µm, 25 µm, 30 µm, 35 µm, 40 µm, 45 µm, 50 µm or any value within the above range.

[0124] For example, along the first direction, the one-sided thickness of the insulating layer is measured at several locations (e.g. 10 locations) using a scanning electron microscope (SEM), and the mean of the several thicknesses is used as the average thickness D2 of the insulating layer.

[0125] With an average thickness of the insulating layer 52 greater than or equal to 10 µm, the insulating layer 52 acts as an effective barrier against burrs, thus reducing the risk of burrs from the positive electrode plate 5 coming into contact with the negative electrode plate 6 or penetrating the separator film; this results in high reliability of the battery cell. With an average thickness of the insulating layer 52 less than or equal to 50 µm, the energy density of the battery cell is increased.

[0126] For example, the insulating layer 52 has the same or almost the same thickness at different points.

[0127] Another example is a fusion zone partially provided between the insulating layer 52 and the positive electrode film layer 51. This fusion zone can arise from the flow of the two dispersions during the application of the slurry for the positive electrode film layer and the insulating layer. In this case, the average thickness of the insulating layer 52 refers to the average thickness of the unfused region.

[0128] Another example involves an overlap region between the insulating layer 52 and the positive electrode film layer 51, wherein the insulating layer 52 is located on the surface of the positive electrode film layer 51 in the overlap region. The average thickness of the insulating layer 52 is understood here to be the thickness in the non-overlapping region.

[0129] Another example is a gap between the insulating layer 52 and the positive electrode film layer 51. In other words, there is an area on the positive electrode body that is not covered by either an insulating layer or a positive electrode film layer.

[0130] In some embodiments, both the overlap region and the gap between the insulating layer 52 and the positive electrode film layer 51 can be present. For example, at one end along the first direction there is an overlap region between the insulating layer 52 and the positive electrode film layer 51; at the other end along the first direction there is a gap between the insulating layer 52 and the positive electrode film layer 51.

[0131] In some embodiments, the dimension of the area in which the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 in the first direction is 0.5 mm to 3 mm.

[0132] The dimension of the area in which the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 in the first direction can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm or any value within this range.

[0133] If the dimension of the area in which the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 in the first direction is greater than or equal to 0.5 mm, this facilitates the preparation of the chamfer 62 and contributes to simplifying the complexity of preparing the negative electrode plate 6. If the dimension of the area in which the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 in the first direction is less than or equal to 3 mm, the risk of lithium plating is reduced, thereby increasing the cycle performance of the battery cell.

[0134] In some embodiments, the chamfer 62 has a smaller dimension in the first direction than the dimension of the area in which the edge of the negative electrode film layer 61 extends beyond the edge of the first section 521 in the first direction. This makes the chamfer 62 easier to produce and reduces the risk of electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate 6.

[0135] In some embodiments, the dimension of the chamfer in the first direction is between 0.5 mm and 1.5 mm.

[0136] The dimension A of the chamfer in the first direction can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm or any value within this range.

[0137] If the chamfer dimension in the first direction is greater than or equal to 0.5 mm, this helps to reduce the risk of electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate; if the chamfer dimension in the first direction is less than or equal to 1.5 mm, this helps to improve the energy density of the battery cell.

[0138] In some embodiments, the dimension of the chamfer 62 in the second direction is larger than the dimension of the chamfer 62 in the first direction.

[0139] If the sealing point of the battery cell's packaging bag is parallel to the second direction – for example, if the seal is made along the second direction – higher pressure forces act on the edge of the packaging bag in the second direction than in the first direction. The larger dimension of the chamfer 62 in the second direction reduces the risk of electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate 6.

[0140] In some embodiments, the dimension of the chamfer 62 in the second direction is between 0.5 mm and 3 mm.

[0141] The dimension B of the chamfer 62 in the second direction can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm or any value within this range.

[0142] If the dimension of the chamfer 62 in the second direction is greater than or equal to 0.5 mm, this helps to reduce the risk of electrolyte leakage due to the pressure exerted on the packaging bag by the negative electrode plate 6; if the dimension of the chamfer 62 in the second direction is less than or equal to 3 mm, this helps to manufacture the chamfer 62 and to simplify the complexity of preparing the chamfer 62.

[0143] In some embodiments, the chamfer 62 is a rounded chamfer, which can be either concave or convex.

[0144] In the embodiments of the present application, the chamfer 62 is designed as a rounding chamfer; the smooth contour further reduces the risk of the packaging bag tearing under pressure or mechanical stress, thus increasing the reliability of the battery cell.

[0145] Fig.Figure 7 shows a schematic structure diagram of a negative electrode plate according to a further embodiment of the present application. As in Fig. As shown in Figure 7, chamfer 62 is a rounded chamfer, and this rounded chamfer is an outwardly convex structure.

[0146] In some embodiments, the chamfer is designed as a concave structure. Compared to a convex structure, a concave structure offers more clearance for the packaging bag, thereby reducing the risk of bag breakage under pressure or impact and thus increasing the reliability of the battery cell.

[0147] Fig. Figure 8 is a schematic structure diagram of a negative electrode plate according to a further embodiment of the present application. As in Fig.As shown in Figure 8, chamfer 62 can also be a right-angled chamfer. The angle between the extensions of the first and second edges can have any value other than 90°, for example 30°, 45°, or 60°.

[0148] In some embodiments, the insulating layer 52 further comprises a second section 522, which is connected to the first section 521 and is arranged at least partially on at least one surface of the positive terminal 502. This contributes to further improving protection against burrs, resulting in higher reliability of the battery cell.

[0149] In some embodiments, the positive electrode body 501 is provided with the insulating layer 52 at both ends along the first direction. The insulating layer 52 near the positive terminal comprises a first section 521 and a second section 522, while the insulating layer 52 located away from the positive terminal comprises only the first section.

[0150] In some embodiments, the negative electrode plate 6 comprises a negative terminal 602 which is opposite the positive terminal 502 in the first direction. This structure allows the battery cell to be manufactured with larger dimensions in the longitudinal direction.

[0151] In some embodiments, the negative electrode current collector 60 of the negative electrode plate 6 comprises a negative electrode body 601 and a negative pole flag 602. The negative pole flag 602 projects out of the negative electrode body 601 in the first direction, and at least one surface of the negative electrode body 601 is coated with the negative electrode film layer 61.

[0152] In some embodiments, the negative electrode plate 6 comprises a negative terminal 602 which is opposite the positive terminal 502 in the first direction. This arrangement makes it possible to manufacture the battery cell with a larger dimension in the longitudinal direction.

[0153] In some embodiments, the negative polar flag 602 can also be arranged on the same side as the positive polar flag 502 in the first direction.

[0154] Fig.Figure 9 is a schematic structure diagram of a battery cell according to an embodiment of the present application. In some embodiments – such as in Fig. As shown in Figure 9, the battery cell 3 comprises an electrode assembly 33 containing a positive electrode plate and a negative electrode plate. The packaging bag 31 consists of two packaging films 310, between which the electrode assembly is arranged; the edges of the two packaging films 310 are connected to each other and form a sealing section. The battery cell 3 also includes electrical electrode terminals 321, which extend between the two packaging films 310 and are electrically connected to the electrode assembly 33.

[0155] For example, the battery cell includes two electrode terminals: a positive electrode terminal for electrical connection with the positive terminal 502 of the electrode arrangement 33 and a negative electrode terminal for electrical connection with the negative terminal 602 of the electrode arrangement 33.

[0156] The battery cell with this structure is a pouch cell. The bonding of the two packaging films creates a sealed space inside the battery cell, which houses the positive electrode plate, the negative electrode plate, and the electrolyte. The electrical connection of the electrode terminals to the electrode assembly allows for easy current extraction.

[0157] In some embodiments, the packaging film 310 comprises an insulating protective layer, a metal layer, and an insulating bonding layer. The insulating bonding layer is located on the side of the metal layer facing the electrode assembly; the insulating protective layer is located on the side of the metal layer facing away from the electrode assembly. In this way, the electrode assembly and the electrolyte can be sealed for protection while simultaneously retaining a degree of flexibility to provide damping in the event of compression or vibration of the battery cell.

[0158] In some embodiments, the material of the insulating protective layer may include nylon, the material of the metal layer aluminum or steel, and the material of the insulating connecting layer polypropylene.

[0159] In some embodiments, the packaging pouch 31 is made of an aluminum-plastic film, and the positive and negative electrode plates are enclosed within the space formed by the aluminum-plastic film. The battery cells of this structure are pouch cells.

[0160] Aluminum-plastic film is a multi-layered, flexible composite packaging material consisting of an outer polymer layer (e.g., nylon or polyester), a middle aluminum layer (e.g., aluminum foil), and an inner polymer layer (e.g., polypropylene or polyethylene). Compared to aluminum or steel casings, aluminum-plastic film casings are used for the manufacture of pouch cells.

[0161] In some embodiments, the battery cell comprises a plurality of positive electrode plates 5 and a plurality of negative electrode plates 6 stacked on top of each other. The stacked structure of the battery cell contributes to better space utilization and thus enables a higher energy density.

[0162] In some embodiments, the battery cell comprises a positive electrode and several negative electrode plates. The positive electrode consists of several positive straight segments and several curved segments, wherein the positive straight segments are connected to the positive curved segments, and the several positive straight segments and the several negative electrode plates are stacked on top of each other.

[0163] In some embodiments, the battery cell comprises several positive electrode plates and one negative electrode plate. The negative electrode plate has several negative straight segments and several curved segments, wherein the negative straight segments are connected to the negative curved segments, and the several negative curved segments and the several positive electrode plates are stacked on top of each other.

[0164] A battery cell with stacked negative and positive electrode plates comprises an electrode assembly that includes the positive electrode plate, the negative electrode plate, and the separator film. The electrode assembly has little or no curvature. This type of battery cell is also known as a stacked battery cell.

[0165] In some embodiments, the insulating layer material comprises inorganic particles and a binder. The inorganic particles comprise at least one of the following elements: aluminum oxide, boehmite, or magnesium oxide. The binder comprises at least one of the following elements: polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, or vinylidene fluoride-trifluorochloroethylene copolymer.

[0166] The inorganic particles exhibit a certain insulating capacity and can block burrs. The binder can bond the inorganic particles to the surface of the positive electrode current collector, thus facilitating the connection between the insulating layer and the positive electrode current collector.

[0167] In some embodiments, the insulating layer 52 may also comprise organic materials (e.g., the insulating layer is an organic insulating layer), and the organic materials include at least one polyacrylate and one polyvinylidene fluoride. All of the above-mentioned materials exhibit good insulating properties, which helps to prevent short circuits and thus improve the reliability of the battery cell.

[0168] In some embodiments, the ionic conductivity of the electrolyte at room temperature can range from 8.5 mS / cm to 20 mS / cm, for example, 8.5 mS / cm, 9 mS / cm, 9.5 mS / cm, 10 mS / cm, 11 mS / cm, 12 mS / cm, 12.5 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 15.5 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, or 20 mS / cm, or a value formed by any two of these values.

[0169] By adjusting the ionic conductivity of the electrolyte to between 8.5 mS / cm and 20 mS / cm, the transport rate of the lithium ions is increased. This compensates for a problem of lithium plating caused by the edge of the negative electrode film layer 61 extending beyond the positive electrode film layer 51, as well as by the edge of the first section 521 of the insulating layer 52, and improves the cycle performance of the battery cell.

[0170] In the embodiments described in this application, the ionic conductivity of the electrolyte can be measured in the following manner.

[0171] After disassembling a battery cell to extract the electrolyte, the electrolyte's ionic conductivity is tested, for example, using a conductivity meter according to HG / T 4067-2015: Approximately 100 ml of the sample to be measured is taken and placed in a dry, clean, and corrosion-resistant bottle; the bottle is sealed airtight and placed in a constant temperature bath at 25 ± 0.5 °C. Once the sample temperature is constant, the bottle stopper is replaced with a rubber stopper containing electrodes. After the temperature has returned to 25 ± 0.5 °C, the reading is taken – this corresponds to the ionic conductivity of the sample.

[0172] In some embodiments, the ionic conductivity of the electrolyte at room temperature is between 12 mS / cm and 16 mS / cm.

[0173] An electrolyte ionic conductivity of at least 12 mS / cm improves the transport rate of lithium ions, reduces the risk of lithium plating, and leads to better cycle performance of the battery cell. Conversely, an electrolyte ionic conductivity of no more than 16 mS / cm reduces the risk of excessive gas formation in the battery cell. This reduces the influence of gas formation on lithium ion transport, which in turn lowers the risk of lithium plating and also contributes to better cycle performance of the battery cell.

[0174] In some embodiments, the electrolyte comprises an electrolyte salt, lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0175] Lithium bis(fluorosulfonyl)imide possesses good dissociation capacity for lithium ions. The combination of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide gives the electrolyte high ionic conductivity, which promotes lithium ion transport, reduces the risk of lithium plating, and improves the cycle performance of the battery cell.

[0176] In some embodiments, the sum of the mass contents of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, based on the total mass of the electrolyte, is between 12% and 20%, for example 12%, 13%, 15%, 16%, 18%, 19%, 20%, or a value formed by any two of these values.

[0177] When the sum of the mass fractions of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, based on the total mass of the electrolyte, is greater than or equal to 12%, the electrolyte exhibits high ionic conductivity. This facilitates lithium ion transport, reduces the risk of lithium plating, and improves the cycle performance of the battery cell. When the sum of the mass fractions of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, based on the total mass of the electrolyte, is a maximum of 20%, the electrolyte has a suitable viscosity. This facilitates lithium ion transport and contributes to improved fast-charging capability of the battery cell.

[0178] In some embodiments, the mass ratio of lithium hexafluorophosphate to lithium bis(fluorosulfonyl)imide is between 1.2 and 9, for example 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 4, 5, 6, 7, 8, 9, or any value within this range. This results in an electrolyte with high ionic conductivity, facilitates lithium ion transport, reduces the risk of lithium plating, and improves the cycle performance of the battery cell.

[0179] In the embodiments of this application, the electrolyte salts in the electrolyte can be quantitatively analyzed by ion chromatography with reference to standard GB / T 34672-2017.

[0180] In some embodiments, the electrolyte salt can consist exclusively of lithium hexafluorophosphate or lithium bis(fluorosulfonyl)imide.

[0181] In some embodiments, the electrolyte comprises a solvent comprising at least a linear carbonate or a linear carboxylate.

[0182] The linear carbonate can have the general formula RO-CO-OR', where R and R' are substituted and unsubstituted alkyl groups, respectively.

[0183] For example, the linear carbonate comprises at least one of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate.

[0184] The linear carboxylate follows the general formula R1-COO-R2, where R1 and R2 can be unsubstituted or substituted alkyl groups.

[0185] For example, the linear carboxylate includes at least one of methyl acetate, ethyl acetate, methyl propionate, propyl acetate, ethyl formate and isopropyl formate.

[0186] Linear carbonate and linear carboxylate exhibit low viscosity.

[0187] The electrolyte containing these solvents also has a low viscosity. This facilitates lithium ion transport and improves the fast-charging capability of the battery cell.

[0188] In some embodiments, the linear carbonate comprises at least one of dimethyl carbonate and one of ethyl methyl carbonate, and the linear carboxylate comprises at least one of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate, and isopropyl formate. The aforementioned solvent has a low viscosity, and the electrolyte containing these solvents also has a low viscosity, which is advantageous for lithium ion transport and thus contributes to improving the fast-charging capability of the battery cell.

[0189] In some embodiments, the sum of the mass fractions of the linear carbonate and the linear carboxylate is between 10% and 90%, based on the total mass of the electrolyte; for example, the sum is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any value within this range.

[0190] If the sum of the mass fractions of linear carbonate and linear carboxylate, based on the total mass of the electrolyte, is greater than or equal to 10%, the electrolyte has a low viscosity; lithium ion transport is facilitated and the fast-charging capability of the battery cell is improved. If the sum of the mass fractions of linear carbonate and linear carboxylate, based on the total mass of the electrolyte, is less than or equal to 90%, gas formation from linear carbonate and linear carboxylate in the battery cell is reduced; the risk of gas accumulation between the separator film and the positive electrode plate 5 and the negative electrode plate 6 is lowered. This reduces the risk of lithium plating and increases the cycle life of the battery cell.

[0191] In some embodiments, the sum of the mass fractions of linear carbonate and linear carboxylate lies between 40% and 80% of the total mass of the electrolyte. This ensures that the sum of the mass fractions of linear carbonate and linear carboxylate remains within a suitable range, allowing the battery cell to achieve both good fast-charging capability and good cycle performance.

[0192] In some embodiments, the solvent further comprises a cyclic carbonate.

[0193] The cyclic carbonate comprises at least one of the following: ethylene carbonate (EC) and propylene carbonate (PC).

[0194] Cyclic carbonate exhibits good dissociation capacity for lithium ions. Combining cyclic carbonate with at least one linear carbonate or linear carboxylate promotes lithium ion transport in the electrolyte, thereby reducing the risk of lithium plating and improving the cycle performance of the battery cell.

[0195] In the embodiments of the present application, the quantitative determination of the solvents in the electrolyte can be carried out according to standard GB / T9722-2006 by means of gas chromatographic analysis.

[0196] In some embodiments, the ratio of electrolyte mass to battery cell capacity is between 2.8 g / Ah and 3.5 g / Ah; exemplary values ​​are 2.8 g / Ah, 2.9 g / Ah, 3.0 g / Ah, 3.1 g / Ah, 3.2 g / Ah, 3.3 g / Ah, 3.4 g / Ah, 3.5 g / Ah, or any value within this range. This ratio ensures good wettability of the positive electrode plate 5 and the negative electrode plate 6 by the electrolyte; lithium ion transport is facilitated, the risk of lithium plating is reduced, and the cycle performance of the battery cell is improved.

[0197] In some embodiments, the ratio of the electrolyte mass to the battery cell capacity is between 3.0 g / Ah and 3.2 g / Ah. This ensures good wettability of both the positive electrode plate 5 and the negative electrode plate 6, which is advantageous for lithium ion transport, thus reducing the risk of lithium plating and improving the cycle performance of the battery cell.

[0198] In some embodiments, the one-sided areal density of the positive electrode plate 5 is between 0.33 g / 1540.25 mm². 2 and 0.45 g / 1540.25 mm 2 , for example at 0.33 g / 1540.25 mm 2 , 0.34 g / 1540.25 mm 2 , 0.36 g / 1540.25 mm 2 , 0.38 g / 1540.25 mm 2 , 0.40 g / 1540.25 mm 2 , 0.41 g / 1540.25 mm 2 , 0.42 g / 1540.25 mm 2 , 0.43 g / 1540.25 mm 2 , 0.44 g / 1540.25 mm 2 , 0.45 g / 1540.25 mm 2or any value within the range mentioned above.

[0199] With a one-sided areal density of the positive electrode plate 5 greater than or equal to 0.33 g / 1540.25 mm² 2 The battery cell exhibits a high energy density. With a one-sided areal density of the positive electrode plate 5 less than or equal to 0.45 g / 1540.25 mm², the cell has a high energy density. 2 This facilitates lithium-ion transport and improves the fast-charging capability of the battery cell.

[0200] In some embodiments, the compaction density of the positive electrode plate 5 is in the range of 2.3 g / cm³. 3 up to 2.65 g / cm³ 3 .

[0201] In this embodiment, the density of the positive electrode plate corresponds to the density when the state of charge (SOC) of the battery cell is 0%. The density of the positive electrode plate can be 2.3 g / cm³. 3 , 2.32 g / cm³ 3, 2.35 g / cm³ 3 , 2.36 g / cm³ 3 , 2.38 g / cm³ 3 , 2.4 g / cm³ 3 , 2.42 g / cm³ 3 , 2.45 g / cm³ 3 , 2.48 g / cm³ 3 , 2.5 g / cm³ 3 , 2.52 g / cm³ 3 , 2.55 g / cm³ 3 , 2.58 g / cm³ 3 , 2.6 g / cm³ 3 , 2.62 g / cm³ 3 , 2.65 g / cm³ 3 or any value within the range mentioned above.

[0202] The density of the positive electrode plate can be measured as follows. At 25 °C, the battery cell is discharged to 2.0 V with a constant current of 0.33 C to obtain a state of charge (SOC) of 0%. The positive and negative electrode plates are then removed from the battery cell, and the thickness of both the electrode plate and the electrode current collector is measured. The electrode plate is then cut into a small circular piece with an area of ​​S1 (for a double-sided coated electrode plate, the protective film on one side can be wiped off beforehand), and its weight is recorded as M1. The protective film is then wiped off the weighed electrode plate, and the weight of the electrode current collector is measured and recorded as M0. Single-sided areal density = (M1 - M0) / S1. Density of compression = Single-sided areal density / (thickness of the electrode plate - thickness of the electrode current collector).Furthermore, the compaction density of the negative electrode plate can also be measured using the method described above.

[0203] With a compaction density of the positive electrode plate 5 greater than or equal to 2.3 g / cm³ 3 The battery cell exhibits a high energy density. This is achieved with a compression density of the positive electrode plate 5 less than or equal to 2.65 g / cm³. 3 This facilitates lithium-ion transport and improves the fast-charging capability of the battery cell.

[0204] In some embodiments, the compaction density of the positive electrode plate 5 is in the range of 2.45 g / cm³. 3 up to 2.6 g / cm³ 3 This is advantageous for improving both the fast charging capability and the energy density of the battery cell.

[0205] In some embodiments, the one-sided areal density of the negative electrode plate 6 is between 0.15 g / 1540.25 mm². 2and 0.22 g / 1540.25 mm 2 .

[0206] The one-sided areal density of the negative electrode plate can be 0.15 g / 1540.25 mm² 2 , 0.16 g / 1540.25 mm 2 , 0.17 g / 1540.25 mm 2 , 0.18 g / 1540.25 mm 2 , 0.19 g / 1540.25 mm 2 , 0.20 g / 1540.25 mm 2 , 0.21 g / 1540.25 mm 2 , 0.22 g / 1540.25 mm 2 or any value within this range.

[0207] With a one-sided areal density of the negative electrode plate 6 greater than or equal to 0.15 g / 1540.25 mm² 2 The energy density of the battery cell increases. With a one-sided areal density of the negative electrode plate 6 less than or equal to 0.22 g / 1540.25 mm², the energy density of the battery cell increases. 2 This facilitates lithium-ion transport and improves the fast-charging capability of the battery cell.

[0208] In some embodiments, the compaction density of the negative electrode plate 6 is in the range of 1.3 g / cm³.3 up to 1.52 g / cm³ 3 .

[0209] In the embodiments of the present application, the specified density of the negative electrode plate refers to that measured at a state of charge (SOC) of 0% of the battery cell. The density of the negative electrode plate can be 1.3 g / cm³. 3 , 1.32 g / cm³ 3 , 1.35 g / cm³ 3 , 1.38 g / cm³ 3 , 1.4 g / cm³ 3 , 1.42 g / cm³ 3 , 1.45 g / cm³ 3 , 1.48 g / cm³ 3 , 1.5 g / cm³ 3 or 1.52 g / cm³ 3 amount to or lie within an area formed therefrom.

[0210] With a compaction density of the negative electrode plate 6 greater than or equal to 1.3 g / cm³ 3 The battery cell exhibits a high energy density. This is achieved with a compression density of the negative electrode plate 6 of less than or equal to 1.52 g / cm³. 3This facilitates lithium-ion transport and improves the fast-charging capability of the battery cell.

[0211] In some embodiments, the compaction density of the negative electrode plate 6 is in the range of 1.35 g / cm³. 3 up to 1.5 g / cm³ 3 In this way, the negative electrode plate 6 has a suitable compaction density that makes it possible to optimally balance both the energy density and the fast charging capability of the battery cell.

[0212] In some embodiments, the positive electrode film layer 51 comprises a positive electrode active material comprising a lithium-containing phosphate.

[0213] Lithium-containing phosphate can refer to lithium-containing transition metal phosphates with an olivine structure, such as lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their modified forms. The modification method can be either doping or surface modification. In the doping method, elements such as titanium can be introduced into the lithium iron phosphate; in the surface modification method, a coating layer can be formed on the surface of the lithium iron phosphate.

[0214] The lithium-containing phosphate exhibits good structural stability, and a lithium phosphate battery cell shows good cycle performance.

[0215] In some embodiments, the mean length of the longest diameter of the primary lithium-containing phosphate particles lies between 300 nm and 800 nm; for example, the mean length can be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or any value within this range. In this way, the lithium ion deposition path is of a suitable length, which has a positive effect on the performance of the battery cell.

[0216] In the embodiments of this application, a primary particle denotes the smallest unit of a particle within a specific observation area. A primary particle may have defects of any kind, but it is impossible to define smaller particles within a primary particle. Primary particles can aggregate under physical forces such as van der Waals forces, but such aggregation is easily broken up by external forces such as ultrasound, stirring, and rolling, so that the main component of the positive electrode active material in the film layer still consists of primary particles.

[0217] For example, the longest diameter of the lithium-containing phosphate refers to the longest straight line passing through the center of the lithium-containing phosphate and extending to the edge of the particle.

[0218] In the embodiments of the present application, the mean length of the longest diameter (maximum dimension) can be determined as follows.

[0219] The battery cell is disassembled to obtain the positive electrode plate. This plate is cut lengthwise to expose the longitudinal section of the positive electrode layer. The longest diameter of the lithium phosphate is determined using scanning electron microscopy (SEM) of the longitudinal section of the positive electrode film layer. For example, 30 lithium phosphate particles are randomly selected from the longitudinal section of the positive electrode film layer, the longest diameter of each of the 30 lithium phosphate particles is measured, and the mean value is calculated.

[0220] In some embodiments, the lithium-containing phosphate comprises a lithium-containing phosphate matrix and a carbon coating that covers at least part of the surface of the lithium-containing phosphate matrix. The carbon coating contributes to improving the conductivity of the lithium-containing phosphate, thus enabling full utilization of the battery cell's capacity.

[0221] In some embodiments, the lithium-containing phosphate comprises lithium iron phosphate doped with at least one element from Al, V, and Ti. The aforementioned dopants improve the electrical conductivity and other properties of the lithium-containing phosphate, which in turn increases the capacity utilization of the battery cell. Furthermore, they also contribute to increasing the compaction density of the positive electrode plate 5 and thus to increasing the energy density of the battery cell.

[0222] In some embodiments, the mass fraction of Al (relative to the total mass of the lithium-containing phosphate) is between 200 ppm and 2500 ppm, the mass fraction of V (vein) between 300 ppm and 2000 ppm, and the mass fraction of Ti (ti) between 1500 ppm and 3500 ppm. With suitable mass fractions of the aforementioned dopants, the battery cell exhibits high energy density, capacity, and cycle stability.

[0223] Based on the total mass of the lithium-containing phosphate, the mass content of Al can be 200 ppm, 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2500 ppm or any value within the above range; the mass content of V can be 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm or any value within the above range; and the mass content of Ti can be 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2500 ppm, 2800 ppm, 3000 ppm ppm, 3200 ppm, 3500 ppm or any value within the above range.

[0224] The elements and their concentrations in the positive electrode active material can be determined using an argon ion cross-section polisher (model JEOL IB-19530CP) and a scanning electron microscope (model Zeiss Sigma 300) (equipped with an energy-dispersive X-ray spectrometer (EDS, model OXFord X-Max-50mm2)).

[0225] As an example, the battery cell is discharged at 25 °C with a constant current of 0.33 C down to 2.0 V to obtain a battery cell with 0% state of charge (SOC). The positive electrode plate is then removed from the battery cell, and the longitudinal section of the positive electrode film layer is prepared using an ion beam polisher. The cross-section of the positive electrode active material particles is then examined with a scanning electron microscope to determine each element and its concentration.

[0226] In some embodiments, the lithium-containing phosphate comprises at least one of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. The aforementioned positive electrode active material with the lithium-containing phosphate exhibits high structural stability, which contributes to improving the cycle performance of the battery cell.

[0227] During the charging and discharging process of a battery cell, active ions such as Li are deintercalated and used, and the molar content of Li in the battery cell varies depending on how the battery cell is discharged to different states. In the list of positive electrode active materials in the present application, the molar content of Li represents the initial state of the material, i.e., the state before input. When the positive electrode active material is used in a battery system, the molar content of Li can change after charge and discharge cycles. In the list of positive electrode active materials in the present application, the molar content of oxygen (O) is only a theoretical value. The release of oxygen from the lattice leads to a change in the molar content of oxygen (O). In practice, the molar content of oxygen (O) fluctuates.

[0228] In some embodiments, the negative electrode film layer 61 comprises a negative electrode active material comprising graphite, wherein at least part of the surface of the graphite is provided with a coating comprising amorphous carbon. This enables the rapid embedding of the lithium ions in graphite, which in turn improves the fast-charging capability of the battery cell.

[0229] In some embodiments, the coating thickness is between 100 nm and 500 nm; for example, the coating thickness can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or any value within this range. This ensures the coating has a suitable thickness that facilitates the incorporation and transport of lithium ions and improves the fast-charging capability of the battery cell.

[0230] In some embodiments, the graphite includes secondary particles. This facilitates lithium ion transport and also contributes to increasing the fast-charging capability of the battery cell.

[0231] In some embodiments, the degree of graphitization of the graphite is between 90% and 94%; for example, the degree of graphitization can be 90%, 91%, 92%, 93%, 94%, or any value within this range. In this way, graphite with a suitable degree of graphitization not only promotes a suitable specific capacity of the graphite but can also control the side reactions in the battery cell within a suitable range, thereby giving the battery cell a suitable capacity and cycle performance.

[0232] In some embodiments, the volume-averaged particle size Dv50 of the graphite lies between 15 µm and 25 µm. This gives the graphite a suitable particle size range, which increases the compaction density of the negative electrode plate 6 and thus contributes to increasing the energy density of the battery cell.

[0233] In some embodiments, the volume-averaged particle size Dv50 of the graphite is between 16 µm and 20 µm. This places the graphite particle size within an optimal range, which also improves the compaction density of the negative electrode plate 6 and increases the energy density of the battery cell.

[0234] In some embodiments, the electrolyte comprises an additive consisting of at least one vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesultone (PS). This additive facilitates film formation at the negative electrode, reduces side reactions at the negative electrode, and thereby improves the cycle life, kinetics, and other performance characteristics of the battery cell.

[0235] In some embodiments, the mass fraction of the additive, based on the total mass of the electrolyte, is less than or equal to 5%. This can be, for example, 5%, 4.8%, 4.5%, 4.2%, 4%, 3.8%, 3.5%, 3%, 2.8%, 2.5%, 2%, 1.8%, 1.5%, 1.2%, 1%, 0.8%, 0.5%, or any value within this range. This additive has a suitable mass fraction that contributes to improving the cycle performance and kinetics of the battery cell.

[0236] In some embodiments, the mass fraction of the additive is between 0.5% and 3% based on the total mass of the electrolyte. This additive has a suitable mass fraction that contributes to improving the cycle performance and kinetics of the battery cell.

[0237] In some embodiments, the battery cell further comprises a separator film arranged between the positive electrode plate 5 and the negative electrode plate 6. The separator film comprises a base film with a thickness of 5 µm to 9 µm, for example 5 µm, 6 µm, 7 µm, 8 µm, 8.5 µm, 9 µm, or any value within the aforementioned range.

[0238] With a base film thickness of at least 5 µm, the separator film exhibits high strength, thereby reducing the risk of lithium dendrites penetrating the separator film and causing internal short circuits in the battery cell; with a base film thickness of a maximum of 9 µm, it is advantageous to reduce the space occupied by the separator film, and the battery cell exhibits a high energy density.

[0239] In some embodiments, the porosity of the separator film is between 40% and 55%, for example 40%, 42%, 45%, 48%, 50%, 52%, 55%, or any value within this range. This allows for better wetting of the separator film by the electrolyte, facilitates lithium ion transport, and reduces the risk of lithium plating, resulting in improved cycle performance of the battery cell. [Battery device]

[0240] The embodiments of the present application provide a battery device comprising a battery cell according to one of the preceding embodiments.

[0241] Fig. Figure 10 is a schematic diagram of the structure of a battery device according to an embodiment of the present application. As in Fig. As shown in Figure 10, the battery device 10 in the embodiments of the present application can comprise a plurality of battery cells 3 to meet different power requirements. The shape of the battery cell 3 can be determined in the embodiments of the present application depending on the specific application. For example, the battery cell 3 can be cylindrical, cuboid, or of other shapes, and the embodiments of the present application are not limited thereto.

[0242] The battery device 10 in the embodiments of the present application can further comprise a housing 11 for receiving several battery cells 3. In the embodiments of the present application, the housing 11 has a hollow structure, and several battery cells 3 are housed inside the housing 11. The housing 11 can consist of two parts, which are here referred to as the first housing part 111 and the second housing part 112, and which are connected to each other. The shapes of the first housing part 111 and the second housing part 112 can be determined based on the shape of the components housed therein, for example, the shape of the battery cells 3 contained therein. At least one of the housing parts 111 or 112 has an opening. As in Fig.As shown in Figure 10, for example, both the first housing part 111 and the second housing part 112 can be designed as hollow cuboids with an opening on one side. The openings of the two housing parts 111 and 112 are arranged opposite each other, and they are joined to form the closed housing 11, which can accommodate several battery cells 3. Several battery cells 3 are connected in parallel, in series, or in a mixed configuration and are housed inside the housing 11, which consists of the first housing part 111 and the second housing part 112.

[0243] Unlike in Fig.As shown in Figure 10, the first housing part 111 and the second housing part 112 can also be designed such that only one of them is a hollow cuboid with an opening, while the other is plate-shaped to close the opening. For example, if the second housing part 112 is an open, hollow cuboid and the first housing part 111 is plate-shaped, the first housing part 111 is placed on the opening of the second housing part 112, thus forming the closed inner volume of the housing 11, in which several battery cells 3 can be accommodated.

[0244] Fig. Figure 11 schematically shows the cooperation between the battery cells and the thermal management component according to an embodiment of this application. Fig.Figure 12 schematically shows the cooperation between the battery cells and the thermal management component according to another embodiment of this application. In some embodiments – shown in the Fig.10 to 12 - the battery device comprises a housing 11, several battery cells 3 which are received in the housing 11 and stacked along a third direction, and a thermal management component 91 for controlling the temperature of several battery cells, wherein each battery cell has a nominal capacity of at least 100 Ah and the surface of each battery cell comprises a first surface 301 and a second surface 302, the area of ​​the first surface being larger than that of the second surface. The first surfaces of the several battery cells face each other along the third direction, the thermal management component and the second surfaces of the several battery cells face each other in a fourth direction, the fourth direction being perpendicular to the third direction.

[0245] The third direction can be the X-direction in Fig. 11 and Fig. 12, and the fourth direction can be the Z-direction in the Fig. 11 and Fig. 12 years old.

[0246] Each battery cell 3 can comprise two first surfaces 301 and two second surfaces 302, wherein the two first surfaces 301 are opposite each other in the X direction and the two second surfaces 302 are opposite each other in the Z direction.

[0247] For example, the first surface 301 is the surface with the largest area of ​​the battery cell.

[0248] For example, the electrode terminals of battery cell 3 are arranged on the first surface 301.

[0249] In this embodiment, the nominal capacity of each battery cell is greater than or equal to 100 Ah. Charging and discharging the battery cells generates a significant amount of heat. By tailoring the thermal management component to the battery cells, their temperature can be better controlled, reducing the risk of excessive cell temperature.

[0250] In some embodiments, the battery device additionally includes a fastening adhesive 92, which is arranged between the thermal management component and the battery cells and serves to fasten the battery cells to the thermal management component. This enables a secure connection between the battery cell and the thermal management component.

[0251] In some embodiments, such as in Fig. As shown in Figure 11, the adhesive 92 is directly bonded to the packaging bag. In other words, the adhesive 92 is directly bonded to the packaging bag of the battery cell 3, which helps to improve the energy density of the battery device.

[0252] In this embodiment, the fastening adhesive 92 is applied directly to the packaging bag, and the battery cells in the battery device are arranged one above the other, thus eliminating the need for a component that connects several battery cells together.

[0253] Fig. Figure 13 is a schematic diagram of the structure of a battery module according to an embodiment of the present application. In some embodiments, the battery device comprises – as, for example, in Fig. 12 and Fig. Figure 13 shows a receiving housing 801 that accommodates at least one battery cell, wherein the adhesive 92 is directly bonded to the housing wall of the receiving housing 801. The receiving housing 801 allows heat to be dissipated more efficiently from the battery cell and reduces the temperature of the battery cell.

[0254] In this embodiment, the battery device comprises at least one battery module 80, which includes the receiving housing 801 and a plurality of battery cells.

[0255] For example, the receiving housing 801 has a U-shaped form. For example, the receiving housing 801 comprises a first wall 8011, a second wall 8012, and a third wall 8013, with the two ends of the second wall 8012 being connected to the first wall 8011 and the third wall 8013, respectively, in the direction of extension. For example, the first wall 8011 and the third wall 8013 extend in the Z-direction, and the second wall 8012 extends in the X-direction.

[0256] For example, the fixing adhesive 92 is attached directly to the first wall 8011 and the third wall 8013 of the receiving housing 801. [Electricity-consuming device]

[0257] The embodiments of the present application provide a power-consuming device comprising a battery cell according to one of the preceding embodiments or a battery device according to one of the preceding embodiments, wherein the battery cell or the battery device serves to store or provide electrical energy.

[0258] The technical solutions described in the embodiments of this application are applicable to various power-consuming devices that use battery devices.

[0259] For example, the power-consuming device could be a mobile phone, a portable device, a laptop computer, an electric vehicle, an electric toy, a power tool, a car, a ship, a spacecraft, or the like. Vehicles could be gasoline-powered cars, natural gas vehicles, or vehicles with alternative propulsion systems. Vehicles with alternative propulsion systems could be pure electric vehicles, hybrid vehicles, or range-extended vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and other spacecraft, etc. Electric toys include stationary or mobile electric toys such as game consoles, electric toy cars, electric toy ships, and electric toy airplanes, etc.Power tools include metalworking tools, grinding tools, assembly tools, and railway vehicle tools such as drills, angle grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The present application does not impose any specific restrictions on the aforementioned power-consuming devices.

[0260] To simplify the explanation, a vehicle is used below as an example of the power-consuming device.

[0261] Fig.Figure 14 shows an exemplary vehicle according to an embodiment of the present application. The vehicle 1 can be a vehicle with an internal combustion engine, a gas-powered vehicle, or a new vehicle; the latter includes purely battery-electric vehicles, hybrid vehicles, and range-extended vehicles. The interior of the vehicle 1 can be equipped with a motor 40, a control unit 30, and a battery device 10. The control unit 30 serves to control the battery device 10 in order to supply the motor 40 with power. For example, the battery device 10 can be installed at the bottom, front, or rear of the vehicle 1. The battery device 10 can be used to supply power to the vehicle 1. For example, the battery device 10 can be used as an operating power source for the vehicle 1, for the electrical system of the vehicle 1, for example, to meet the energy requirements of the vehicle 1 during starting, navigation, and operation.In some embodiments of the present application, the battery device 10 can serve not only as an operating current source for the vehicle 1, but also as a propulsion current source for the vehicle, replacing the fuel or natural gas wholly or partially to provide propulsion current for the vehicle 1. [Positive electrode plate]

[0262] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector can comprise a base layer of polymer material and a metal layer formed on at least one surface of the polymer base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0263] In some embodiments, the positive electrode active material can be a positive electrode active material known in the art for a battery. For example, the positive electrode active material can comprise one or more of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their modified derivatives. However, the present application is not limited to these materials, and other conventional materials suitable for use as a positive electrode active material for a battery can also be used. The positive electrode active material can be used alone or in combination with two or more. Examples of lithium transition metal oxides include, among others, lithium cobalt oxides (e.g., LiCoO2), lithium nickel oxides (e.g., LiNiO2), and lithium manganese oxides (e.g., LiNiO2).LiMnO2, LiMn2O4), lithium-nickel-cobalt oxides, lithium-manganese-cobalt oxides, lithium-nickel-manganese oxides, lithium-nickel-cobalt-manganese oxides (e.g. LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0,5 Co 0,2 Mn 0.3 O2 (also abbreviated as NCM523), LiNi 0,5 Co 0,25 Mn 0,25 O2 (also abbreviated as NCM211), LiNi 0,6 Co 0,2 Mn 0,2 O2 (abbreviated as NCM622), LiNi 0,8 Co 0,1 Mn 0,1 O2 (also abbreviated as NCM811), lithium nickel cobalt aluminum oxides (e.g. LiNi) 0,85 Co 0,1 Al 0,05O2) and their modified derivatives. Examples of lithium-containing phosphate with an olivine structure include lithium iron phosphate (such as LiFePO4 (also called LFP)), lithium iron phosphate carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate carbon composites.

[0264] During the charging and discharging process of a battery cell, active ions such as lithium are deintercalated and used, and the molar fraction of lithium in the battery cell varies depending on the discharge state. In the list of positive electrode active materials of the present application, the molar fraction of lithium represents the initial state of the material, i.e., the state before the addition of lithium. When the positive electrode active material is used in a battery system, the molar fraction of lithium can change after charge and discharge cycles. In the list of positive electrode active materials of the present application, the molar fraction of oxygen (O) is only a theoretical value. The release of oxygen from the lattice leads to a change in the molar fraction of oxygen (O). In practice, the molar fraction of oxygen (O) fluctuates.

[0265] In some embodiments, the positive electrode film layer further comprises a binder. For example, the binder may comprise at least one of the following substances: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0266] In some embodiments, the positive electrode film layer further comprises a conductive material. For example, the conductive material can comprise at least one of the following: superconducting carbon, acetylene carbon black, carbon black, Ketjen black, a carbon dot, a carbon nanotube, graphene, and a carbon nanofiber.

[0267] In one embodiment, the positive electrode plate can be manufactured as follows: by forming a positive electrode slurry from the components described above. The positive electrode slurry is typically generated by dispersing and uniformly stirring the positive electrode active material, a conductivity, a binder, and optionally other components in a solvent (as well as N-methylpyrrolidone). The positive electrode slurry is then applied to the positive electrode current collector, and after drying, cold pressing, and further processing, the positive electrode plate is obtained. [Negative electrode plate]

[0268] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. A copper foil can serve as the negative electrode current collector. The composite current collector can be formed by forming a metallic material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0269] The negative electrode film layer comprises a negative electrode active material. The negative electrode active material can be a negative electrode active material known in the art for a battery. For example, the negative electrode active material can comprise at least one of the following materials: a soft carbon, a hard carbon, a silicon-based material, a tin-based material, a titanate, and the like. The silicon-based material can be selected from at least one of the following: elemental silicon, a silicon-oxygen compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of the following: elemental tin, a tin oxide compound, and a tin alloy.However, the present application is not limited to these materials, and other conventional materials suitable for use as negative electrode active material for a battery may also be used. The negative electrode active material can be used alone or in combination with two or more materials.

[0270] The negative electrode film layer may further comprise a binder. The binder may be selected from at least one of the following substances: styrene-butadiene rubber (SBR), sodium carboxymethylcellulose (CMC-Na), water-soluble unsaturated resin SR-1B, aqueous acrylate resins (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS)), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0271] The negative electrode film layer can further comprise a conductive material. The conductive material can be selected from at least one of the following materials: superconducting carbon, acetylene carbon black, carbon black, Ketjen black, a carbon dot, a carbon nanotube, graphene, and a carbon nanofiber.

[0272] In one embodiment, the negative electrode plate can be manufactured as follows: The components mentioned above for manufacturing the negative electrode plate are processed into a negative electrode slurry. For example, the negative electrode active material, the conductive agent, the binder, and optionally other components are mixed in a solvent (deionized water) to form a negative electrode slurry for the negative electrode plate. The negative electrode slurry is then applied to the negative electrode current collector; after drying, cold pressing, and further processing steps, the negative electrode plate is obtained. [Separator]

[0273] The separator serves to separate the positive electrode plate and the negative electrode plate. The present application is not subject to any specific restrictions regarding the type of separator, and any known porous separator film with good chemical and mechanical stability can be selected and used.

[0274] In one embodiment, the separator film material can be selected from at least one of the following: glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film without any particular restriction. If the separator film is a multi-layer composite film, the materials of the individual layers can be the same or different without any particular restriction.

[0275] The embodiments of the present application provide a battery device comprising a battery cell according to one of the preceding embodiments.

[0276] The embodiments of the present application constitute a power-consuming device comprising the battery cell according to one of the preceding embodiments or the battery device according to one of the preceding embodiments, wherein the battery cell or the battery device is used to provide electrical energy.

[0277] The embodiments described below are exemplary and serve only to illustrate the present application; they should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the technical literature or product instructions should be followed. All reagents and instruments used without manufacturer information are commercially available, conventional products. [Examples of Implementation]Example of Implementation 1(1) Preparation of the negative electrode plate

[0278] A mixture of synthetic graphite as the negative electrode active material, conductive carbon black as a conducting agent, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC-Na) as a thickener is uniformly mixed in a ratio of 96.5:0.5:2:1 and fully aerated with deionized water to obtain a negative electrode slurry. The negative electrode slurry is applied uniformly to both surfaces of the copper foil as the negative electrode current collector. After drying, compaction, cutting, and shaping, a negative electrode plate is obtained. The volume-averaged particle size Dv50 of the synthetic graphite is 12 µm, and the volumetric particle size distribution Dv90 of the synthetic graphite is 20 µm. The synthetic graphite includes secondary particles and is coated on its surface with a 300 nm thick layer of amorphous carbon.The graphitization degree of the artificial graphite is 92%. At a state of charge (SOC) of 0%, the compaction density of the negative electrode plate is 1.4 g / cm³. 3 and the one-sided areal density of the negative electrode film layer 0.17 g / 1540.25 mm² 2 .

[0279] A chamfer is provided at the junction between the first and second edges of the negative electrode plate. The chamfer dimension A is 1 mm in the first direction, and the chamfer dimension B is 1.5 mm in the second direction. (2) Preparation of the positive electrode plate

[0280] Lithium iron phosphate as the positive electrode active material, conductive carbon black as a conductor, and polyvinylidene fluoride (PVDF) as a binder are uniformly mixed and completely dissolved in N-methylpyrrolidone (NMP) in a mass ratio of 97:1:2.0 to obtain a positive electrode slurry. Simultaneously, inorganic aluminum oxide particles and polyvinylidene fluoride (PVDF) are also dispersed in N-methylpyrrolidone (NMP) under stirring, yielding the insulating slurry. Subsequently, the positive electrode slurry and the insulating slurry are evenly applied to both surfaces of the aluminum foil as the positive electrode current collector to create a positive electrode plate with the positive electrode film layer and the insulating layer. The positive electrode plate is then formed by cutting and attaching the terminal tabs.

[0281] The positive electrode current collector comprises a positive electrode body and a positive terminal protruding from the electrode body in a first direction. The positive electrode body has a coating area and a transition area located between the coating area and the positive terminal protruding. The positive electrode film layer is applied to both surfaces of the coating area. The insulating layer is applied to both ends of the positive electrode film layer in the first direction. The insulating layer near the positive terminal protruding along the first direction consists of a first section and a second section. The first section is applied to both surfaces of the coating area. The second section is applied to both surfaces of a portion of the positive terminal protruding. The first section and the second section are connected to each other.In the first direction, the width D1 of the first section is 2 mm and the average thickness D2 of the insulating layer is 30 µm.

[0282] In the first direction, the dimension H of the area in which the negative electrode film layer extends beyond the first section of the insulating layer is 1.5 mm.

[0283] At a battery cell state of charge of 0% SOC, the density of the positive electrode film layer is 2.5 g / cm³. 3 and the one-sided density of the positive electrode film layer 0.38 g / 1540.25 mm 2 . (3) Preparation of the electrolyte

[0284] In a glove box under an argon atmosphere (H2O content < 10 ppm, O2 content <1 ppm), the electrolyte salt lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide are dissolved in a mass ratio of 2 : 1 in a mixture of organic solvents dimethyl carbonate (DMC), ethyl acetate (EA), ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and stirred until complete homogeneity is achieved.

[0285] Based on the total mass of the electrolyte, the mass content of the electrolyte salt LiPF6 is 9.6% and the mass content of LIFSI is 4.8%; the weight ratio of the organic solvents DMC : EA : EMC : EC is 20 : 40 : 10 : 30. (4) Separator film

[0286] The separator film comprises a base film which is a 7-µm polyethylene film. (5) Preparation of the battery cell

[0287] The positive electrode plate, the separator film, and the negative electrode plate are cut into pieces and stacked sequentially, with the separator film acting as an insulator between the positive and negative electrode plates to form the electrode assembly. This assembly is then placed in an aluminum-plastic film, filled with electrolyte, and vacuum-packed. After a subsequent settling period, formation, and shaping, the battery cell is completed. Examples 2-5

[0288] The difference between embodiments 2-5 and embodiment 1 is that the volume-averaged particle size Dv50 of the graphite is different.

[0289] Furthermore, the volumetric particle size distribution Dv90 of the graphite can take on different values ​​depending on the volume-averaged particle size Dv50. Examples 6-7

[0290] The difference between embodiments 6-7 and embodiment 1 is that the dimension H by which the negative electrode film layer extends beyond the first section of the insulating layer along the first direction is different. Examples 8-9

[0291] The difference between embodiments 8-9 and embodiment 1 is that the width D1 of the first section of the insulating layer is different along the first direction. Examples 10-11

[0292] The difference between embodiments 10-11 and embodiment 1 is that the thickness D2 of the insulating layer is different. Comparative examples 1

[0293] The difference between comparative example 1 and embodiment 1 is that the connection point between the first edge and the second edge of the negative electrode plate is not provided with a chamfer. Comparative example 2

[0294] The difference between comparative example 2 and embodiment 1 is that the negative electrode film layer does not extend beyond the first section of the insulating layer along the first direction. Comparative example 3

[0295] The difference between comparative example 3 and embodiment 1 is that the volume-averaged particle size Dv50 of the graphite is less than 8 µm. Comparative example 4

[0296] The difference between comparative example 4 and embodiment 1 is that the volume-averaged particle size Dv50 of the graphite is greater than 20 µm. Table 1 Data from the exemplary implementations and comparative examples Dv50 / µm Dv90 / µm H / mm D1 / mm D2 / µm Number of cycles at 80% SOH Yes / No Leakage Example 1 12 20 1,5 2 30 2500 no leakage Example 2 8 15 1,5 2 30 2350 no leakage Example 3 10 18 1,5 2 30 2480 no leakage Example 4 15 25 1,5 2 30 2420 no leakage Example 5 20 40 1,5 2 30 2320 no leakage Example 6 12 20 0,5 2 30 2550 no leakage Example 7 12 20 3 2 30 2350 no leakage Example 8 12 20 1,5 1 30 2450 no leakage Example 9 12 20 1,5 3 30 2500 no leakage Example 10 12 20 1,5 2 10 2420 no leakage Example 11 12 20 1,5 2 50 2500 no leakage Comparative example 1 12 20 1,5 2 30 2200 leakage Comparative example 2 12 20 0 2 30 2230 leakage Comparative example 3 6 12 1,5 2 30 1900 no leakage Comparative example 4 22 45 1,5 2 30 2000 no leakage

[0297] In Table 1, H denotes the dimension of the area in which the edge of the negative electrode film layer extends beyond the edge of the first section in the first direction; D1 denotes the dimension of the first section in the first direction; D2 denotes the average thickness of the insulating layer; Dv50 denotes the volume-averaged particle size of the graphite; and Dv90 denotes the volumetric particle size distribution of the graphite. Table 2: Data from selected implementation examples H / mm Energy density / Wh / L Example 1 1,5 400 Example 6 0,5 403 Example 7 3 393 Table 3 Data of selected implementation examples D1 / mm D2 / µm Energy density / Wh / L Self-discharge test K-value / mV / h Example 1 2 30 400 0,015 Example 8 1 30 402 0,025 Example 9 3 30 394 0,031 Example 10 2 10 401 0,035 Example 11 2 50 396 0,014

[0298] In the embodiments of the present application, the cycle performance of a battery cell is specified by the number of cycles in which its discharge capacity is reduced to 80% of the capacity of the first cycle; the higher this number of cycles, the better the cycle performance. The reliability of the battery cell is determined by whether leakage occurs. This leakage can be quantified by the rate of increase in the thickness of the battery cell after heat storage at 60 °C.

[0299] As shown in embodiments 1-11 and comparative examples 1-4, the battery cell can achieve both good cycle performance and high reliability by having the edge of the negative electrode film layer extend beyond the edge of the first section, a chamfer at the junction between the first and second edges of the negative electrode plate, and the graphite having a volume-averaged particle size Dv50 of 8 µm to 20 µm.

[0300] As shown in embodiments 1-5, the battery cell achieves both good cycle performance and high reliability with a volume-averaged graphite particle size Dv50 between 8 µm and 20 µm. The same applies to a volume-averaged graphite particle size distribution Dv90 between 15 µm and 40 µm. A volume-averaged graphite particle size Dv50 between 10 µm and 15 µm contributes to a further improvement in cycle performance while maintaining high reliability. A volume-averaged graphite particle size distribution Dv90 between 18 µm and 25 µm also improves cycle performance while maintaining high reliability.

[0301] As shown in embodiment 1 and embodiments 6-7, adjusting the dimension H - defined as the area in which the edge of the negative electrode film layer extends beyond the edge of the first section along the first direction - to 0.5 mm to 3 mm results in the battery cell having good cycle performance, high energy density and high reliability.

[0302] As shown in embodiment 1 and embodiments 8-9, adjusting the dimension D1 of the first section of the insulating layer along the first direction to 1 mm to 3 mm results in the battery cell optimally combining cycle performance, high energy density and high reliability.

[0303] As shown in embodiment 1 and embodiments 10-11, the thickness of the insulating layer from 10 µm to 50 µm enables the battery cell to simultaneously have excellent cycle performance, high energy density and high reliability.

[0304] It should be noted that the present application is not limited to the embodiments mentioned above. The aforementioned embodiments are merely exemplary, and all embodiments that exhibit essentially the same structure and effect as the technical teaching in the sense of the present technical solution also fall within the scope of protection of the present application. Furthermore, embodiments obtained by modifications of the described embodiments, as well as by combining individual features from different embodiments, without departing from the spirit of the present application, are also included.

[0305] The following is a brief introduction to the test methods for the physicochemical and performance parameters relevant in the embodiments of this application. It is understood that the following test methods are merely examples and that other test methods known to those skilled in the art may also be used. 1. Performance test

[0306] At 45 °C, the battery cell is charged to 3.65 V with a constant current of 0.5 C, then held at a constant voltage until the current drops to 0.05 C; this is followed by a 10-minute rest period. The battery cell is then discharged to 2.0 V with a constant current of 1 C – this corresponds to one charge-discharge cycle; the resulting discharge capacity is recorded as the capacity of the first cycle. After another 10-minute rest period, the described cycle is repeated until the discharge capacity has decreased to 80% of the initial cycle capacity; the number of cycles performed up to this point is determined as the total number of cycles. 2. Leakage test

[0307] At 25 °C, the thickness of the battery cell is measured as H0. The battery cell is placed on a metal plate heated to 60 °C and then heated. After 2 hours, the thickness of the battery cell is measured as H1. If the increase in thickness (H1 - H0) / H0 is less than 5%, a leak is assumed.

[0308] In this test method, an insufficient increase in thickness indicates that the packaging bag is damaged and there is a risk of electrolyte leakage. 3. Energy density test

[0309] At 25 °C, the battery cell is charged with a constant current of 0.33 C up to the cutoff voltage of 3.65 V, then recharged with a constant voltage to ≤ 0.05 C, and finally discharged with a constant current of 0.33 C down to the lower cutoff voltage of 2.0 V. The discharge energy E0 and the discharge capacity C0 are recorded. The external dimensions (length, width, and thickness) of the cell are measured, and the cell volume V0 is calculated. The energy density of the battery cell is E0 / V0 and is expressed in Wh / L. 4. Self-discharge test

[0310] At 25 ± 2 °C, the battery cell is discharged to reach a state of charge (SOC) of 30%. After 12 hours, the initial voltage V0 is measured. The battery cell is then stored at the same temperature for another 48 hours, and the final voltage V1 is measured. The self-discharge rate K is calculated using the formula (V0 - V1) / 48 and is expressed in mV / h. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] CN 202510901332.5

[0001] Cited non-patent literature

[0000] GB / T19077-2016

[0106] GB / T 34672-2017

[0179] GB / T9722-2006

[0195]

Claims

[1] Battery cell comprising: a positive electrode plate, a negative electrode plate and a packaging bag, wherein the positive electrode plate and the negative electrode plate are contained within the packaging bag, wherein the positive electrode plate comprises a positive electrode current collector, a positive electrode film layer and an insulating layer, wherein the positive electrode current collector comprises a positive electrode body and a positive pole flag projecting from the positive electrode body in a first direction, wherein the positive electrode body comprises a coating region and a transition region, wherein in the first direction the transition region is located at at least one end of the coating region, wherein the positive electrode film layer is arranged on at least one surface of the coating region, and wherein the insulating layer has a first section arranged on at least one surface of the transition region. wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein an edge of the negative electrode film layer extends in the first direction beyond an edge of the first section near the positive pole flag; wherein A chamfer is provided at the junction between a first edge and a second edge of the negative electrode plate, wherein the first edge runs in the first direction and the second edge runs in a second direction, both the first direction and the second direction being perpendicular to the thickness direction of the negative electrode plate. wherein the negative electrode film layer comprises a negative electrode active material comprising graphite, wherein a volume-averaged particle size Dv50 of the graphite is 8 µm to 20 µm. [2] Battery cell according to claim 1, wherein the volume-averaged particle size Dv50 of the graphite is between 10 µm and 15 µm. [3] Battery cell according to claim 1, wherein a volumetric particle size distribution Dv90 of the graphite is between 15 µm and 40 µm. [4] Battery cell according to claim 3, wherein the volumetric particle size distribution Dv90 of the graphite is between 18 µm and 25 µm. [5] Battery cell according to claim 1, wherein the dimension of the first section in the first direction is between 1 mm and 3 mm. [6] Battery cell according to claim 1, wherein the average thickness of the insulating layer is between 10 µm and 50 µm. [7] Battery cell according to claim 1, wherein the area in which the edge of the negative electrode film layer extends in the first direction beyond the edge of the first section near the positive terminal has a dimension of 0.5 mm to 3 mm. [8] Battery cell according to claim 1, wherein the dimension of the chamfer in the first direction is smaller than the dimension of the area in which the edge of the negative electrode film layer extends beyond the edge of the first section near the positive terminal. [9] Battery cell according to claim 1, wherein the dimension of the chamfer in the first direction is between 0.5 mm and 1.5 mm. [10] Battery cell according to claim 1, wherein the dimension of the chamfer in the second direction is larger than the dimension of the chamfer in the first direction. [11] Battery cell according to claim 1, wherein the dimension of the chamfer in the second direction is between 0.5 mm and 3 mm. [12] Battery cell according to claim 1, wherein the chamfer is a rounded chamfer. [13] Battery cell according to claim 12, wherein the rounded chamfer is concave. [14] Battery cell according to claim 13, wherein the insulating layer further comprises a second section which is connected to the first section and is arranged on at least one surface of a part of the positive terminal flag. [15] Battery cell according to claim 1, wherein the negative electrode plate comprises a negative terminal, wherein the negative terminal and the positive terminal are opposite each other in the first direction. [16] Battery cell according to claim 1, wherein the battery cell comprises an electrode arrangement comprising the positive electrode plate and the negative electrode plate, wherein the packaging bag comprises two packaging films, wherein the electrode arrangement is located between the two packaging films, wherein edges of the two packaging films are connected to each other and form a sealing section, wherein the battery cell further comprises electrode connections which run between the two packaging films and are electrically connected to the electrode arrangement. [17] Battery cell according to claim 16, wherein the packaging film comprises an insulating protective layer, a metal layer and an insulating connecting layer, wherein the insulating connecting layer is arranged on a side of the metal layer facing the electrode arrangement and the insulating protective layer is arranged on a side of the metal layer facing away from the electrode arrangement. [18] Battery cell according to claim 1, wherein the battery cell comprises an electrolyte, wherein the ionic conductivity of the electrolyte is 8.5 mS / cm to 20 mS / cm. [19] Battery cell according to claim 18, wherein the ionic conductivity of the electrolyte at room temperature is between 12 mS / cm and 16 mS / cm. [20] Battery cell according to claim 18, wherein the electrolyte comprises a solvent comprising a linear carbonate and / or a linear carboxylate. [21] Battery cell according to claim 20, wherein the linear carbonate comprises at least one of dimethyl carbonate and ethyl methyl carbonate and the linear carboxylate comprises at least one of ethyl acetate, methyl acetate, methyl propionate, propyl acetate, ethyl formate and isopropyl formate. [22] Battery cell according to claim 20, wherein, based on the total mass of the electrolyte, the sum of the mass contents of the linear carbonate and the linear carboxylate is between 10% and 90%. [23] Battery cell according to claim 22, wherein, based on the total mass of the electrolyte, the sum of the mass contents of the linear carbonate and the linear carboxylate is between 40% and 80%. [24] Battery cell according to claim 20, wherein the solvent further comprises a cyclic carbonate. [25] Battery cell according to claim 18, wherein the ratio of the mass of the electrolyte to the capacity of the battery cell is between 2.8 g / Ah and 3.5 g / Ah. [26] Battery cell according to claim 25, wherein the ratio of the mass of the electrolyte to the capacity of the battery cell is between 3.0 g / Ah and 3.2 g / Ah. [27] Battery cell according to claim 1, wherein the one-sided areal density of the positive electrode plate is between 0.33 g / 1540.25 mm² 2 and 0.45 g / 1540.25 mm 2 lies. [28] Battery cell according to claim 1, wherein the compression density of the positive electrode plate is between 2.3 g / cm³ 3 and 2.65 g / cm² 3 lies. [29] Battery cell according to claim 28, wherein the compression density of the positive electrode plate is between 2.45 g / cm³ 3 and 2.6 g / cm³ 3 lies. [30] Battery cell according to claim 1, wherein the one-sided areal density of the negative electrode plate is between 0.15 g / 1540.25 mm² 2 and 0.22 g / 1540.25 mm 2 lies. [31] Battery cell according to claim 1, wherein the compression density of the negative electrode plate is between 1.3 g / cm³ 3 and 1.52 g / cm³ 3 lies. [32] Battery cell according to claim 31, wherein the compression density of the negative electrode plate is between 1.35 g / cm³ 3 and 1.5 g / cm² 3 lies. [33] Battery cell according to claim 1, wherein the positive electrode film layer comprises a positive electrode active material comprising a lithium-containing phosphate. [34] Battery cell according to claim 33, wherein the mean length of the longest diameter of primary particles of the lithium-containing phosphate is between 300 nm and 800 nm. [35] Battery cell according to claim 33, wherein the lithium-containing phosphate comprises a lithium-containing phosphate matrix and a carbon coating covering at least part of the surface of the lithium-containing phosphate matrix. [36] Battery cell according to claim 35, wherein the lithium-containing phosphate matrix comprises lithium iron phosphate doped with at least one element of Al, V and Ti. [37] Battery cell according to claim 36, wherein, based on the total mass of the lithium-containing phosphate, the mass content of Al is between 200 ppm and 2500 ppm, the mass content of V is between 300 ppm and 2000 ppm and the mass content of Ti is between 1500 ppm and 3500 ppm. [38] Battery cell according to claim 1, wherein at least part of the surface of the graphite is provided with a coating comprising amorphous carbon. [39] Battery cell according to claim 38, wherein the thickness of the coating is between 100 nm and 500 nm. [40] Battery cell according to claim 38, wherein the graphite comprises secondary particles. [41] Battery cell according to claim 38, wherein the degree of graphitization of the graphite is between 90% and 94%. [42] Battery cell according to claim 1, wherein the battery cell comprises an electrolyte comprising an additive, wherein the additive comprises at least one of vinylene carbonate, fluoroethylene carbonate and 1,3-propanesultone. [43] Battery cell according to claim 42, wherein the mass content of the additive is less than or equal to 5% in relation to the total mass of the electrolyte. [44] Battery cell according to claim 43, wherein the mass content of the additive is between 0.5% and 3%, based on the total mass of the electrolyte. [45] Battery device comprising several battery cells according to any one of claims 1 to 44. [46] Battery device according to claim 45, wherein the battery device comprises: a case; the multiple battery cells which are contained in the housing and are stacked along a third direction, each battery cell having a nominal capacity greater than or equal to 100 Ah and the surface of each battery cell comprising a first surface and a second surface, the area of ​​the first surface being greater than the area of ​​the second surface, the first surfaces of the multiple battery cells being opposite each other along the third direction; a thermal management component for regulating the temperature of the multiple battery cells, wherein the thermal management component and the second surfaces of the multiple battery cells are opposite each other in a fourth direction, the fourth direction being perpendicular to the third direction. [47] Battery device according to claim 46, wherein the battery device further comprises a fastening adhesive arranged between the thermal management component and the multiple battery cells and serving to fix the multiple battery cells to the thermal management component. [48] ​​Battery device according to claim 47, wherein the fastening adhesive is directly bonded to the packaging bag. [49] Battery device according to claim 47, wherein the battery device further comprises a receiving housing in which at least one of the several battery cells is received, wherein the fastening adhesive is directly connected to a housing wall of the receiving housing. [50] Power-consuming device comprising a battery cell according to any one of claims 1 to 44 or a battery device according to any one of claims 45 to 49, wherein the battery cell or the battery device is used to provide electrical energy.

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