Battery cell, battery device and power-consuming device

Abstract

Battery cell, characterized in that it comprises an electrode arrangement, an electrolyte solution and a housing body, wherein the electrode arrangement is received in the housing body and the housing body is made of a pouch material; and wherein the electrode arrangement comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet and the negative electrode sheet are arranged stacked alternately, the separator being arranged between the positive electrode sheet and the negative electrode sheet, which are adjacent to each other; wherein the edge region of the negative electrode sheet is provided with a chamfer; wherein the projection of the positive electrode sheet in the stacking direction of the electrode sheet falls completely within the projection of the adjacent negative electrode sheet in the stacking direction of the electrode sheet; and wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein, in the fully discharged state, the one-sided coating areal density of the negative electrode film layer is 170 mg / 1540.25 mm² 2 up to 200 mg / 1540.25 mm 2 is, and the compaction density is 1.4 g / cm³ 3 up to 1.6 g / cm³ 3 amounts.

Description

Technical field

[0001] The present application relates to the technical field of battery cells and in particular to a battery cell, a battery device and a power-consuming device. State of the art

[0002] In recent years, battery cells have been widely used in energy storage systems for hydroelectric, coal, wind and solar power plants, as well as in many different areas such as electric hand tools, electric bicycles, electric motorcycles, electric vehicles and aerospace.

[0003] With the rapid development and updating of national and industry standards for energy storage and traction batteries, the demands on the energy density, safety, and cycle life of battery cells are increasing year by year. It is difficult with current technology to improve both of the aforementioned performance characteristics simultaneously, which represents a pressing technical challenge that needs to be addressed in this field. Disclosure of the invention

[0004] In view of the problems mentioned above, the present application provides a battery cell, a battery device and a power-consuming device, each of which is described below.

[0005] A first aspect of the present application provides a battery cell comprising an electrode arrangement, an electrolyte solution, and a housing body, wherein the electrode arrangement is received in the housing body and the housing body is made of a pouch material; and wherein the electrode arrangement comprises a positive electrode sheet, a negative electrode sheet, and a separator, wherein the positive electrode sheet and the negative electrode sheet are arranged stacked alternately, the separator being arranged between the positive electrode sheet and the negative electrode sheet, which are adjacent to each other; wherein the edge region of the negative electrode sheet is provided with a chamfer; wherein the projection of the positive electrode sheet in the stacking direction of the electrode sheet falls completely within the projection of the adjacent negative electrode sheet in the stacking direction of the electrode sheet;and wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein in the fully discharged state the one-sided coating areal density of the negative electrode film layer is 170 mg / 1540.25 mm; 2 up to 200 mg / 1540.25 mm 2 is, and the compaction density is 1.4 g / cm³ 3 up to 1.6 g / cm³ 3 amounts.

[0006] By using the pouch material as the housing body, a stacked arrangement of the positive electrode sheet and the negative electrode sheet, and the application of a thick coating process for the film layer, where the one-sided coating areal density of the negative electrode film layer in the fully discharged state is 170 mg / 1540.25 mm² 2 up to 200 mg / 1540.25 mm 2This process improves the battery's volume energy density, thus facilitating an increase. However, this process improvement also presents new technical challenges: Firstly, the pouch material used for hot-press sealing is employed in the stacked electrode assembly. This pouch material shrinks and deforms plastically at high temperatures, leading to stress concentrations at the edges and corners of the electrode assembly. This results in an abnormal gap between the stacked electrode sheets at the edges of the assembly, particularly at the corners, which can lead to lithium plating and compromise the battery's long-term safety. Secondly, the thick plating process increases the lithium ion transport path, thereby increasing the ion transport resistance. This can lead to local overpolarization of the electrode, resulting in a reduction of the negative electrode's potential.As a result, metallic lithium is deposited on the negative electrode surface, which further impairs both the operational reliability and the cycle life of the battery.

[0007] In this application, the projection of the positive electrode sheet in the stacking direction falls entirely within the projection of the adjacent negative electrode sheet in the stacking direction. The unprojected area, acting as an overhang, mitigates the lithium plating phenomenon that occurs during charging. Furthermore, by positioning the chamfer at the edge of the larger negative electrode sheet, the stress concentration caused by pouch material contraction can be distributed at the corners. Conversely, the stress at the edges primarily acts on the overhang area, reducing its influence on the projected overlap area of ​​the positive and negative electrode sheets.This ensures a tight overlap area and an intact interface, mitigating safety risks caused by lithium plating due to stresses at the edges and corners. Compared to a hard-case battery, a pouch battery offers less space within the casing for electrolyte solution. Consequently, using a lower density of the negative electrode film layer allows for increased porosity and improved fluid retention. This reduces the risk of lithium plating caused by the extended transport path of lithium ions within a thickly coated film layer. Furthermore, it reduces the risk of electrolyte depletion in the stacked pouch battery during extended cycling processes, thus improving the battery's cycle life.Typically, the specific capacity of the negative electrode active material far exceeds that of the positive electrode active material. Consequently, the density of the negative electrode film layer has a relatively small influence on the battery's energy density, while still ensuring the battery's energy density.

[0008] In any embodiment, the thickness of the negative electrode film layer on one side is 70 µm to 90 µm in the fully discharged state, optionally 75 µm to 90 µm.

[0009] Studies show that in a fully discharged state, battery capacity struggles to meet ever-increasing market demands if the thickness of the negative electrode film layer on one side is too thin. Conversely, excessive thickness can easily lead to problems such as reduced kinetics and lithium plating. Maintaining the thickness of the negative electrode film layer on one side within the aforementioned range promotes further improvements in battery capacity while simultaneously addressing the issue of lithium plating.

[0010] In any embodiment, the chamfer comprises a C-chamfer or an R-chamfer, optionally being an R-chamfer.

[0011] The R-chamfer is a rounded chamfer that achieves a smooth transition, resulting in uniform stress distribution and a reduction in stress concentration points. However, this requires machining with a rounding tool of a specific radius, leading to higher tooling costs. Furthermore, tool changes for different radius roundings can increase production costs and times. The C-chamfer is a 45° chamfer angle, which removes identical dimensions from adjacent surfaces. This can be achieved with a standardized helical chamfer tool or by adjusting the tool's feed angle. The tool offers greater versatility and is relatively less expensive, although its effectiveness in reducing stress concentrations is less pronounced than that of the R-chamfer.

[0012] In any embodiment, the radius of the R-phase is 0.5% to 2.5% of the width of the negative electrode current collector, optionally being 0.8% to 2%.

[0013] Selecting the radius of the R-chamfer within the aforementioned range results in both a distribution of the stresses at the edges, thereby reducing the probability of lithium plating at the edges, and a maximization of the coating area, giving the battery a high energy density and capacity.

[0014] In any embodiment, the dimension of the C-phase is 0.5% to 1.5% of the width of the negative electrode current collector.

[0015] If the dimensions of the C-phase are within the aforementioned range, this also reduces the likelihood of lithium plating at the edges and simultaneously increases the coating area of ​​the negative electrode film layer, so that the battery has both high energy density and excellent cycle performance.

[0016] In any embodiment, the ratio of the dimensional difference in either the longitudinal or the lateral direction between any negative electrode sheet and any positive electrode sheet, each adjacent to the other, to the dimension of the negative electrode sheet in that direction is 0.5% to 1.5%.

[0017] The ratio of the length or width of the negative electrode sheet to the positive electrode sheet lies within the range mentioned above. The negative electrode sheet has an overhang area that reduces lithium plating during the charging process while simultaneously ensuring the surface area, i.e., the coating area, of the positive electrode sheet. This further improves the capacity and energy density of the battery cell.

[0018] In any embodiment, the CB value of the battery cell is in the range of 1.05 to 1.15, optionally 1.08 to 1.15, where the CB value denotes the ratio of the capacity of the negative electrode sheet to the capacity of the positive electrode sheet per unit area.

[0019] The embodiments of the present application further reduce the increased risk of lithium plating within the battery of the present application by designing the CB value of the battery cell to be between 1.05 and 1.15. At the same time, both the initial efficiency and the cycle life of the battery are improved.

[0020] In any embodiment, the negative electrode film layer comprises a negative electrode active material, wherein the negative electrode active material comprises a graphite material and has an OI value of 1.7 to 5, optionally 2.5 to 3.5, wherein the OI value = I 004 / I 110 applies, where I 004 the integral surface of the diffraction peak of the 004 crystal plane in X-ray diffraction analysis is and I 110 the integral surface of the diffraction peak of the 110-crystal plane.

[0021] The OI value indicates the degree of order in the material in the direction of the 004 or 110 crystal plane. A high OI value means that the graphite material exhibits greater anisotropy, with expansion and contraction being more concentrated in one direction. This negatively affects structural stability and impairs the uniformity of lithium intercalation / deintercalation. A low OI value indicates that the negative electrode active material exhibits greater uniformity of lithium intercalation, thereby increasing the effective frontal area for lithium intercalation within the negative electrode film layer. An OI value of the graphite material within the aforementioned range indicates that the graphite material tends towards isotropy. Consequently, volume changes during charging and discharging occur more uniformly, thus extending the battery's cycle life.This can also ensure that sufficient electrolyte solution remains at the interface while simultaneously improving the lithium ion transport rate between the solid and liquid. This approach prevents lithium plating during long-term cycling, thus maintaining a balance between long-term safety and battery lifespan.

[0022] In any embodiment, the electrolyte filling coefficient of the battery cell is 2.5 g / Ah to 4 g / Ah, optionally 2.7 g / Ah to 3.2 g / Ah.

[0023] The electrolyte fill coefficient is the ratio of the mass (g) of the electrolyte solution to the capacity (Ah) of the battery cell. By controlling the electrolyte fill coefficient of lithium-ion batteries within the aforementioned range, the risk of lithium plating, which results from local electrolyte depletion within the electrode sheet, is reduced. Such electrolyte depletion occurs during extended cycles because pouch batteries have a limited ability to suppress expansion.

[0024] In any embodiment, in the stacking direction of the electrode sheet in the electrode arrangement, the dimensions of the negative electrode current collector decrease sequentially by ΔL1 in either the longitudinal or the transverse direction, independently of each other, where 15 µm ≤ ΔL1 ≤ 120 µm.

[0025] In any embodiment, the positive electrode sheet in the electrode arrangement comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the dimensions of the positive electrode current collector decrease sequentially by ΔL2 in either the longitudinal or the transverse direction independently of each other, where 15 µm ≤ ΔL2 ≤ 120 µm.

[0026] In the stacking direction, the length and / or width of the negative and positive electrode current collectors decrease sequentially. This ensures improved uniformity in sealing the pouch material and reduces the likelihood of wrinkling at the current collector edges. It covers not only the surface of the outermost electrode sheet, but the intermediate stacked electrode sheets also contribute to voltage distribution. This further minimizes lithium plating at the edges and corners of the electrode array, thus improving both battery safety and cycle life.

[0027] In any embodiment, the projection of the battery cell onto a first projection surface is a first projection trapezoid, wherein the first projection trapezoid is optionally an isosceles trapezoid; and wherein the first projection surface denotes the plane defined by the width direction and the stacking direction of the electrode arrangement.

[0028] In any embodiment, the projection of the battery cell onto a second projection surface is a second projection trapezoid, wherein the second projection trapezoid is optionally an isosceles trapezoid; and wherein the second projection surface denotes the plane defined by the longitudinal direction and the stacking direction of the electrode arrangement.

[0029] The cross-section of the electrode array projection onto the first projection surface is trapezoidal, and / or the cross-section of the electrode array projection onto the second projection surface is trapezoidal. This allows the stresses exerted on the electrode array during heat sealing, particularly at edges and corners, to be effectively distributed within the pouch material housing. The isosceles trapezoidal structure of the battery cell balances the stresses on the different sides, thus reducing the likelihood of lithium plating due to stress concentrations.

[0030] In any embodiment, the degree of the two angles formed between the leg of the first projection trapezoid and the longer base of the first projection trapezoid is α1 and α2, respectively, where 70° ≤ α1 ≤ 85°, 75° ≤ α2 ≤ 85° and optionally α1 = α2.

[0031] In any embodiment, the degree of the two angles formed between the leg of the second projection trapezoid and the longer base of the second projection trapezoid is β1 and β2, respectively, where 70° ≤ β1 ≤ 85°, 70° ≤ β2 ≤ 85° and optionally β1 = β2.

[0032] The two angles formed between the leg of the first projection trapezoid and the longer base of the first projection trapezoid, and / or the two angles formed between the leg of the second projection trapezoid and the longer base of the second projection trapezoid, lie within the aforementioned range. This optimizes the stress distribution while mitigating the effects of excessive angles on the coating area of ​​the active material, thereby ensuring the battery's energy density.

[0033] In any embodiment, the edge region of the positive electrode sheet is also provided with a chamfer.

[0034] If the edge of the positive electrode sheet is not chamfered, then no cutting processes are required for the positive electrode sheet. This avoids the problem of burr formation on the positive electrode current collector or the detachment of the active material during cutting, which could directly expose the positive electrode current collector to the electrolyte solution. However, the lack of a chamfer on the edge of the positive electrode sheet, in conjunction with the chamfer on the edge of the negative electrode sheet, limits the dimensions of the positive electrode sheet. This is to prevent the right angles at the edge of the positive electrode sheet from extending beyond the boundary of the negative electrode sheet, which could lead to lithium plating or puncture of the separator and thus a short circuit. Consequently, a significant area is lost.By positioning the chamfer at the edge of the positive electrode sheet, not only are the stresses at the corners of the electrode sheet further reduced, but the dimensions of the positive electrode sheet are also improved. This maximizes the overlap area with the projection of the negative electrode sheet, thereby increasing the energy density of the battery cell.

[0035] In any embodiment, the thickness of the negative electrode current collector is 6 µm to 10 µm.

[0036] In any embodiment, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the thickness of the positive electrode current collector is 12 µm to 15 µm.

[0037] The thickness of the current collector within the aforementioned area serves a dual purpose: On the one hand, it increases the mechanical strength of the stacked pouch battery and improves the battery's resistance to expansion; on the other hand, it can increase the current passage area, thereby reducing the internal resistance of the electrode sheet and suppressing internal heating within the electrode sheet, thus improving the safety and long-term lifespan of the battery.

[0038] In any embodiment, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the length of the positive electrode current collector and / or the negative electrode current collector is 520 mm to 570 mm.

[0039] In any embodiment, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the width of the positive electrode current collector and / or the negative electrode current collector is 100 mm to 130 mm.

[0040] The length and width of the positive electrode current collector and / or the negative electrode current collector within the aforementioned range serve, on the one hand, to improve heat dissipation and extend the battery's cycle life. On the other hand, the battery cell, which has a current collector of the aforementioned dimensions, can be adapted to the available space in the module or battery pack, thereby improving grouping efficiency and facilitating higher energy density at the module and battery pack level.

[0041] A second aspect of the present application provides a battery device comprising a battery cell according to the first aspect of the present application.

[0042] A third aspect of the present application provides a power-consuming device comprising at least one battery cell according to the first aspect of the present application and / or a battery device according to the second aspect of the present application. Brief description of the drawings

[0043] Unless otherwise indicated, in the drawings, the same reference numerals denote identical or similar components or elements in the different drawings. The drawings are not necessarily to scale. It should be understood that these drawings represent only some of the embodiments as disclosed in the present application and are not to be regarded as limiting the scope of protection of the present application. Fig. 1 is a schematic top view of an electrode arrangement according to an embodiment of the present application; Fig. Figure 2 is a schematic front view of the electrode arrangement according to an embodiment of the present application; Fig. Figure 3 is a three-dimensional schematic representation of the electrode arrangement according to an embodiment of the present application; Fig.Figure 4 is a three-dimensional schematic representation of a battery cell according to an embodiment of the present application; Fig. Figure 5 is a schematic representation of a power-consuming device according to an embodiment of the present application. Reference symbol list:

[0044] 1. Electrode assembly, 11. Separator, 12. Positive electrode sheet, 121. First positive electrode sheet, 13. Negative electrode sheet, 131. First negative electrode sheet, 132. Second negative electrode sheet, 14. Positive electrode tab, 15. Negative electrode tab, 5. Battery cell. Detailed descriptions

[0045] The following section describes in detail embodiments of a battery cell, a battery device, and a power-consuming device specifically disclosed in the present application, possibly with reference to the drawings. However, an unnecessarily detailed description can be omitted. For example, a detailed description of known facts and a repeated description of essentially the same structure can be avoided. This is to prevent the following description from becoming unnecessarily lengthy, thus facilitating understanding by those skilled in the art. Furthermore, the drawings and the following description serve to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0046] The “range” disclosed in the present application is defined in terms of a lower bound and an upper bound. A given range is defined by selecting a lower bound and an upper bound. The selected lower bound and upper bound define the limits of the specific range. The ranges thus defined may or may not include the end values ​​and may be specified in any combination; that is, any lower bound can be combined with any upper bound to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, then ranges of 60 to 110 and 80 to 120 are also conceivable. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, then all of the following ranges are conceivable: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.In the present 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 "0 to 5" means that all real numbers between "0 to 5" are listed therein, and "0 to 5" is simply an abbreviation for these number combinations. Furthermore, if a particular parameter is specified 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.

[0047] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form new technical solutions, and such technical solutions should be considered to be contained in the disclosure of the present application.

[0048] Unless otherwise stated, all technical features and optional technical features of the present application can be combined to form new technical solutions, and such technical solutions should be considered to be contained in the disclosure of the present application.

[0049] Unless otherwise stated, all steps of the present application may be carried out sequentially or in any order, but preferably sequentially. For example, "the method comprises steps (a) and (b)" means that the method may comprise steps (a) and (b) carried out sequentially, or that it may comprise steps (b) and (a) carried out sequentially. For example, the aforementioned method may further comprise step (c), which means that step (c) may be added in any order. For example, the method may comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0050] In the present application, the terms “several” and “different” refer to two or more.

[0051] Unless otherwise stated, the terms used in this application have the generally known meanings which are usually understood by the person skilled in the art.

[0052] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be measured using various test methods commonly used in the art. For example, they can be measured according to the test methods specified in the embodiments of this application. Unless otherwise specified, the test temperature for each parameter is 25 °C.

[0053] The battery mentioned in the embodiments of the present application may refer to a single physical module comprising one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in the present application may comprise a battery cell, a battery module, or a battery pack, etc.

[0054] The battery cell is the smallest unit that makes up the battery and can independently perform charging and discharging functions.

[0055] The battery cell comprises an electrode array and an electrolyte.

[0056] The electrode array typically comprises a positive electrode sheet and a negative electrode sheet. The negative electrode sheet is the electrode where lithium ions are absorbed or lithiated during charging and where lithium is released or delithiated during discharging. The positive electrode sheet is the electrode where lithium ions are released or delithiated during charging and where lithium is absorbed or lithiated during discharging.

[0057] In some embodiments and as in Fig.As shown in Figure 1, the electrode arrangement of the battery cell comprises a positive electrode sheet 12, a negative electrode sheet 13, a separator 11, a positive electrode tab 14, and a negative electrode tab 15. Here, direction X denotes the longitudinal direction along the electrode arrangement. Direction Y denotes the lateral direction along the electrode arrangement. Direction Z denotes the stacking direction along the electrode arrangement.

[0058] The battery cell may further comprise an outer packaging, which can be used to encapsulate the electrode assembly and the electrolyte. The outer packaging is a soft packaging, for example, a bag-like soft packaging. The material of the soft packaging can be plastic, for example, one or more types of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0059] The number of electrode assemblies contained in the battery cell 1 can be one or more and can be adjusted as required. If multiple battery cells are present, they are connected in series, parallel, or a mixed configuration via bus components. In some embodiments, the battery can be a battery module; if multiple battery cells are present, they are arranged and secured to form a single battery module. In some embodiments, the battery can be a battery pack, the battery pack comprising a box body and battery cells, with the battery cells or battery modules being contained within the box body. In some embodiments, the box body can be designed as part of a vehicle chassis.For example, part of the box body can become at least part of a floor plate of the vehicle, or part of the box body can become at least part of a cross member and a longitudinal member of the vehicle.

[0060] In some embodiments, the battery can serve as an energy storage device. Energy storage devices include energy storage containers, electrical energy storage cabinets, etc.

[0061] In some embodiments, the battery cells can be assembled into a battery module, where the number of battery cells contained in the module can be multiple. The exact number can be adjusted depending on the application and capacity of the battery module. Within the battery module, several battery cells can be arranged sequentially along its length. Of course, other arrangements are also possible. Furthermore, the multiple battery cells can be secured by fastening elements.

[0062] Optionally, the battery module can also include a housing with a receiving space, in which the multiple battery cells are received.

[0063] In some embodiments, the aforementioned battery modules can also be assembled into a battery pack. The number of battery modules contained in the battery pack can be adjusted depending on the application and the battery pack's capacity.

[0064] The battery pack can comprise a housing and multiple battery modules arranged within the housing. The housing can include an upper and a lower housing; the upper housing covers the lower housing, forming an enclosed space to contain the battery modules. The multiple battery modules can be arranged within the housing in any configuration.

[0065] As the battery industry advances, the demands placed on battery cells are continuously increasing, and the standards for energy density in energy storage and traction batteries are rising year by year. State-of-the-art improvements are primarily achieved through the following technical approaches: the use of stacked electrode arrangements, which improves space utilization by 5% to 8% compared to conventional wound structures, thereby increasing the active material loading in the battery cell; the use of lightweight pouch housings, which further increases battery loading and improves battery energy density; and, in the electrode manufacturing phase, thick coating processes increase the areal density of the active material while simultaneously reducing the proportion of inactive materials such as current collectors and separators, thus improving volume energy density.However, studies show that the likelihood of lithium plating in battery cells using the aforementioned methods increases significantly, negatively impacting the battery's cycle life and safety. Therefore, ensuring both cycle life and battery safety at high energy density remains a pressing technical challenge that must be addressed simultaneously.

[0066] A first aspect of the present application provides a battery cell characterized in that it comprises an electrode arrangement, an electrolyte solution and a housing body, wherein the electrode arrangement is received in the housing body and the housing body is made of a pouch material; and wherein the electrode arrangement comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet and the negative electrode sheet are arranged stacked alternately, the separator being arranged between the positive electrode sheet and the negative electrode sheet, which are adjacent to each other; wherein the edge region of the negative electrode sheet is provided with a chamfer;wherein the projection of the positive electrode sheet in the stacking direction of the electrode sheet falls completely within the projection of the adjacent negative electrode sheet in the stacking direction of the electrode sheet; and wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector, wherein in the fully discharged state the one-sided coating areal density of the negative electrode film layer is 170 mg / 1540.25 mm; 2 up to 200 mg / 1540.25 mm 2 is, and the compaction density is 1.4 g / cm³ 3 up to 1.6 g / cm³ 3 amounts.

[0067] By using the pouch material as the housing body, a stacked arrangement of the positive electrode sheet and the negative electrode sheet, and the application of a thick coating process for the film layer, where the one-sided coating areal density of the negative electrode film layer in the fully discharged state is 170 mg / 1540.25 mm² 2 up to 200 mg / 1540.25 mm 2This process improves the battery's volume energy density, thus facilitating an increase. However, this process improvement also presents new technical challenges: Firstly, the pouch material used for hot-press sealing is employed in the stacked electrode assembly. This pouch material shrinks and deforms plastically at high temperatures, leading to stress concentrations at the edges and corners of the electrode assembly. This results in an abnormal gap between the stacked electrode sheets at the edges of the assembly, particularly at the corners, leading to lithium plating and compromising the battery's long-term safety. Secondly, the thick coating process increases the lithium ion transport path, thereby increasing the ion transport resistance. This can lead to local overpolarization of the electrode, resulting in a reduction of the negative electrode's potential.As a result, metallic lithium is deposited on the negative electrode surface, which further impairs both the operational reliability and the cycle life of the battery.

[0068] In this application, the projection of the positive electrode sheet in the stacking direction falls entirely within the projection of the adjacent negative electrode sheet in the stacking direction. The unprojected area, acting as an overhang, mitigates the lithium plating phenomenon that occurs during charging. Furthermore, by positioning the chamfer at the edge of the larger negative electrode sheet, the stress concentration caused by pouch material contraction can be distributed at the corners. Conversely, the stress at the edges primarily acts on the overhang area, reducing its influence on the projected overlap area of ​​the positive and negative electrode sheets.This ensures a tight overlap area and an intact interface, mitigating safety risks caused by lithium plating due to stresses at the edges and corners. Compared to a hard-case battery, a pouch battery offers less space within the casing for electrolyte solution. Consequently, using a lower density of the negative electrode film layer allows for increased porosity and improved fluid retention. This reduces the risk of lithium plating caused by the extended transport path of lithium ions within a thickly coated film layer. Furthermore, it reduces the risk of electrolyte depletion in the stacked pouch battery during extended cycling processes, thus improving the battery's cycle life.Typically, the specific capacity of the negative electrode active material far exceeds that of the positive electrode active material. Consequently, the density of the negative electrode film layer has a relatively small influence on the battery's energy density, while still ensuring the battery's energy density.

[0069] In some embodiments, the one-sided coating area density of the negative electrode film layer in the fully discharged state is optionally 170 mg / 1540.25 mm². 2 , 175 mg / 1540.25 mm 2 , 180 mg / 1540.25 mm 2 , 185 mg / 1540.25 mm 2 , 190 mg / 1540.25 mm 2 , 195 mg / 1540.25 mm 2 or 200 mg / 1540.25 mm 2 or lies within a value range between any two of the above.

[0070] In the present application, the term "the one-sided coating areal density of the negative electrode film layer" has a meaning known in the art and can be tested using methods known in the art. For example, a one-sided coated and compacted negative electrode sheet is used (in the case of a double-sided coated negative electrode sheet, the negative electrode film layer can first be wiped off one side). This is punched out into small circular discs with an area S1, the weight of which is weighed and recorded as M1. Subsequently, the negative electrode film layer of the negative electrode sheet is wiped off, and the weight of the current collector is weighed and recorded as M0. The one-sided coating areal density of the negative electrode film layer = (M1 - M0) / S1. To ensure the accuracy of the test results, several sets (e.g.,10 sets) of the samples to be tested are examined, and the average value is calculated as the test result.

[0071] In some embodiments, the compaction density of the negative electrode film layer in the fully discharged state is optionally 1.4 g / cm³. 3 , 1.41 g / cm³ 3 , 1.42 g / cm³ 3 , 1.43 g / cm³ 3 , 1.44 g / cm³ 3 , 1.45 g / cm³ 3 , 1.46 g / cm³ 3 , 1.47 g / cm³ 3 , 1.48 g / cm³ 3 , 1.49 g / cm³ 3 , 1.50 g / cm² 3 , 1.51 g / cm³ 3 , 1.52 g / cm³ 3 , 1.53 g / cm³ 3 , 1.54 g / cm³ 3 , 1.55 g / cm³ 3 , 1.56 g / cm³ 3 , 1.57 g / cm³ 3 , 1.58 g / cm³ 3 , 1.59 g / cm³ 3 or 1.6 g / cm³ 3 or lies within a value range between any two of the above.

[0072] In the present application, the fully discharged state refers to the state achieved by placing the battery in an oven at a temperature of 25 °C and leaving it there for 2 hours until its temperature stabilizes at 25 °C, then discharging the battery to 2.0 V with a constant current of 1 / 3 C, followed by a resting period of half an hour, and then discharging it to 2.0 V with a constant current of 0.04 C.

[0073] The density of the negative electrode film layer can be measured using methods known in engineering. For example, the battery is placed in an oven at 25 °C and left to stand for 2 hours until its temperature stabilizes at 25 °C. The battery is then discharged to 2.0 V at a constant current of 1 / 3 C and left to stand for half an hour. It is then discharged again to 2.0 V at a constant current of 0.04 C. The battery is disassembled to obtain the negative electrode sheet. The remaining electrolyte solution is treated with dimethyl carbonate solvent, the electrode sheet is dried, and cut into small circular discs with an area S. Their mass is determined as W1, and the thickness T1 of the negative electrode sheet is measured with a high-precision micrometer. Finally, the negative electrode film layer of the weighed electrode sheet is wiped off.The mass of the current collector is weighed and designated W2. The thickness of the current collector is measured with a high-precision micrometer and designated T2. The density PD of the negative electrode film layer is calculated as follows: PD = (W1 - W2) / [(T1 - T2) × S].

[0074] In some embodiments, the thickness of the negative electrode film layer on one side is 70 µm to 90 µm in the fully discharged state, optionally 75 µm to 90 µm.

[0075] In some embodiments, the one-sided thickness of the negative electrode film layer in the fully discharged state is optionally 70 µm, 71 µm, 72 µm, 73 µm, 74 µm, 75 µm, 75.1 µm, 76 µm, 76.1 µm, 77 µm, 78 µm, 79 µm, 80 µm, 81 µm, 82 µm, 82.8 µm, 83 µm, 84 µm, 85 µm, 85.8 µm, 86 µm, 87 µm, 88 µm, 89 µm, 89.6 µm or 90 µm, or lies within a value range between the above. any two of them.

[0076] Studies show that in a fully discharged state, battery capacity struggles to meet ever-increasing market demands if the thickness of the negative electrode film layer on one side is too thin. Conversely, excessive thickness can easily lead to problems such as reduced kinetics and lithium plating. Maintaining the thickness of the negative electrode film layer on one side within the aforementioned range promotes further improvements in battery capacity while simultaneously addressing the issue of lithium plating.

[0077] In some embodiments, the chamfer includes a C-chamfer or an R-chamfer, optionally being an R-chamfer.

[0078] The R-chamfer is a rounded chamfer that achieves a smooth transition, resulting in uniform stress distribution and a reduction in stress concentration points. However, this requires machining with a rounding tool of a specific radius, leading to higher tooling costs. Furthermore, tool changes for different radius roundings can increase production costs and times. The C-chamfer is a 45° chamfer angle, which removes identical dimensions from adjacent surfaces. This can be achieved with a standardized helical chamfer tool or by adjusting the tool's feed angle. The tool offers greater versatility and is relatively less expensive, although its effectiveness in reducing stress concentrations is less pronounced than that of the R-chamfer.

[0079] In some embodiments, the radius of the R-phase is 0.5% to 2.5% of the width of the negative electrode current collector, optionally being 0.8% to 2%.

[0080] In some embodiments, the radius of the R-chamfer is optionally 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5% of the width of the negative electrode sheet, or lies in a range of values ​​between any two of the above.

[0081] Selecting the radius of the R-chamfer within the aforementioned range results in both a distribution of the stresses at the edges, thereby reducing the probability of lithium plating at the edges, and a maximization of the coating area, giving the battery a high energy density and capacity.

[0082] In some embodiments, the dimension of the C-phase is 0.5% to 1.5% of the width of the negative electrode current collector.

[0083] In some embodiments, the dimension of the C-phase is optionally 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5% of the width of the negative electrode current collector, or lies in a range of values ​​between any two of the above.

[0084] If the dimensions of the C-phase are within the aforementioned range, this also reduces the likelihood of lithium plating at the edges and simultaneously increases the coating area of ​​the negative electrode film layer, so that the battery has both high energy density and excellent cycle performance.

[0085] In some embodiments and in the stacking direction of the electrode sheet in the electrode arrangement, the ratio of the dimensional difference in either the longitudinal or the lateral direction between any negative electrode sheet and any positive electrode sheet, each adjacent to the other, to the dimension of the negative electrode sheet in that direction is 0.5% to 1.5%.

[0086] In some embodiments and in the stacking direction of the electrode sheet in the electrode arrangement, the ratio of the dimensional difference in either the longitudinal or the lateral direction between any negative electrode sheet and any positive electrode sheet, each adjacent to the other, to the dimension of the negative electrode sheet in that direction is optionally 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%, or lies in a range of values ​​between any two of these.

[0087] In the present application, as an example, the ratio of the dimensional difference in either the longitudinal or the lateral direction between any adjacent negative electrode sheet and any adjacent positive electrode sheet to the dimension of the negative electrode sheet in that direction can be calculated as follows. As in Fig.As shown in Figure 2, this comprises a first positive electrode sheet 121, a first negative electrode sheet 131 adjacent to the first positive electrode sheet 121, and a second negative electrode sheet 132 adjacent to the first positive electrode sheet 121. P1 In the figure, L denotes the length of the first positive electrode sheet 121. N1 In the figure, L denotes the length of the first negative electrode sheet 131 and L N2 In the figure, denotes the length of the second negative electrode sheet; the ratio of the dimensional difference in the longitudinal direction between the adjacent negative and positive electrode sheets to the dimension of the negative electrode sheet in this direction comprises (L N1 - L P1 ) / L N1 and (L N2 - L P1 ) / L N2 , where the two ratios above are in the range of 0.5% to 1.5%.

[0088] The ratio of the length and width of the negative and positive electrode sheets lies within the range mentioned above. The negative electrode sheet has an overhang area that reduces lithium plating during charging while simultaneously ensuring a sufficient surface area, i.e., the coating area, of the positive electrode sheet. This further improves the capacity and energy density of the battery cell.

[0089] In some embodiments, the CB value of the battery cell is in the range of 1.05 to 1.15, optionally 1.08 to 1.15, where the CB value denotes the ratio of the capacity of the negative electrode sheet to the capacity of the positive electrode sheet per unit area.

[0090] In some embodiments, the CB value of the battery cell is optionally 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14 or 1.15, or lies within a range of values ​​between any two of the above.

[0091] The embodiments of the present application further reduce the increased risk of lithium plating within the battery of the present application by designing the CB value of the battery cell to be between 1.05 and 1.15. At the same time, both the initial efficiency and the cycle life of the battery are improved.

[0092] In some embodiments, the negative electrode film layer comprises a negative electrode active material, wherein the negative electrode active material comprises a graphite material and has an OI value of 1.7 to 5, optionally 2.5 to 3.5, where the OI value = I 004 / I 110 applies, where I 004 the integral surface of the diffraction peak of the 004 crystal plane in X-ray diffraction analysis is and I 110 the integral surface of the diffraction peak of the 110-crystal plane.

[0093] In some embodiments, the OI value of the graphite material is optionally 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 4, 4.5 or 5, or lies in a range of values ​​between any two of the above.

[0094] The OI value indicates the degree of order in the material in the direction of the 004 or 110 crystal plane. A high OI value means that the graphite material exhibits greater anisotropy, with expansion and contraction being more concentrated in one direction. This negatively affects structural stability and impairs the uniformity of lithium intercalation / deintercalation. A low OI value indicates that the negative electrode active material exhibits greater uniformity of lithium intercalation, thereby increasing the effective frontal area for lithium intercalation within the negative electrode film layer. An OI value of the graphite material within the aforementioned range indicates that the graphite material tends towards isotropy. Consequently, volume changes during charging and discharging occur more uniformly, thus extending the battery's cycle life.This can also ensure that sufficient electrolyte solution remains at the interface while simultaneously improving the lithium ion transport rate between the solid and liquid. This approach prevents lithium plating during long-term cycling, thus maintaining a balance between long-term safety and battery lifespan.

[0095] In some embodiments, the electrolyte filling coefficient of the battery cell is 2.5 g / Ah to 4 g / Ah, optionally 2.7 g / Ah to 3.2 g / Ah.

[0096] In some embodiments, the electrolyte fill coefficient of the battery cell is optionally 2.5 g / Ah, 2.6 g / Ah, 2.7 g / Ah, 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, 3.6 g / Ah, 3.7 g / Ah, 3.8 g / Ah, 3.9 g / Ah or 4 g / Ah, or lies in a range of values ​​between any two of the above.

[0097] The electrolyte fill coefficient is the ratio of the mass (g) of the electrolyte solution to the capacity (Ah) of the battery cell. By controlling the electrolyte fill coefficient of lithium-ion batteries within the aforementioned range, the risk of lithium plating, which results from local electrolyte depletion within the electrode sheet, is reduced. Such electrolyte depletion occurs during extended cycles because pouch batteries have a limited ability to suppress expansion.

[0098] In some embodiments, in the stacking direction of the electrode sheet in the electrode arrangement, the dimensions of the negative electrode current collector decrease sequentially by ΔL1 in either the longitudinal or the lateral direction, independently of each other, where 15 µm ≤ ΔL1 ≤ 120 µm.

[0099] In some embodiments, ΔL1 is optionally 15 µm, 20 µm, 22 µm, 25 µm, 30 µm, 35 µm, 40 µm, 45 µm, 50 µm, 55 µm, 60 µm, 65 µm, 70 µm, 75 µm, 80 µm, 85 µm, 90 µm, 91 µm, 95 µm, 100 µm, 105 µm, 110 µm, 115 µm or 120 µm, or lies in a range of values ​​between any two of the above.

[0100] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein in the stacking direction of the electrode sheet in the electrode arrangement the dimensions of the positive electrode current collector decrease sequentially by ΔL2 in either the longitudinal or the transverse direction independently of each other, where 15 µm ≤ ΔL2 ≤ 120 µm.

[0101] In some embodiments, ΔL2 is optionally 15 µm, 20 µm, 22 µm, 25 µm, 30 µm, 35 µm, 40 µm, 45 µm, 50 µm, 55 µm, 60 µm, 65 µm, 70 µm, 75 µm, 80 µm, 85 µm, 90 µm, 91 µm, 95 µm, 100 µm, 105 µm, 110 µm, 115 µm or 120 µm, or lies in a range of values ​​between any two of the above.

[0102] Take in the stacking direction, as in Fig.Figure 3 shows the length and / or width of the negative electrode current collector and the positive electrode current collector being sequentially cut. This ensures improved uniformity in sealing the pouch material and reduces the likelihood of wrinkling at the edges of the current collector. It covers not only the surface of the outermost electrode sheet, but the intermediate electrode sheets also contribute to voltage distribution. This further minimizes lithium plating at the edges and corners of the electrode assembly, thus improving both the safety and cycle life of the battery.

[0103] In some embodiments, the projection of the battery cell onto a first projection surface forms a first projection trapezoid, wherein the first projection trapezoid is optionally an isosceles trapezoid; and wherein the first projection surface denotes the plane defined by the width direction and the stacking direction of the electrode arrangement.

[0104] In some embodiments, the projection of the battery cell onto a second projection surface is a second projection trapezoid, wherein the second projection trapezoid is optionally an isosceles trapezoid; and wherein the second projection surface denotes the plane defined by the longitudinal direction and the stacking direction of the electrode arrangement.

[0105] The cross-section of the electrode array projection onto the first projection surface is trapezoidal, and / or the cross-section of the electrode array projection onto the second projection surface is trapezoidal. This allows the stresses exerted on the electrode array during heat sealing, particularly at edges and corners, to be effectively distributed within the pouch material housing. The isosceles trapezoidal structure of the battery cell balances the stresses on the different sides, thus reducing the likelihood of lithium plating due to stress concentrations.

[0106] In some embodiments, the degree of the two angles formed between the leg of the first projection trapezoid and the longer base of the first projection trapezoid is α1 and α2, respectively, where 70° ≤ α1 ≤ 85°, 70° ≤ α2 ≤ 85° and optionally α1 = α2.

[0107] In some embodiments, α1 is optionally 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84° or 85° or lies in a range of values ​​between any two of the above.

[0108] In some embodiments, α2 is optionally 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84° or 85° or lies in a range of values ​​between any two of the above.

[0109] In some embodiments, the degree of the two angles formed between the leg of the second projection trapezoid and the longer base of the second projection trapezoid is β1 and β2, respectively, where 70° ≤ β1 ≤ 85°, 70° ≤ β2 ≤ 85° and optionally β1 = β2.

[0110] In some embodiments, β1 is optionally 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84° or 85° or lies in a range of values ​​between any two of the above.

[0111] In some embodiments, β2 is optionally 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84° or 85° or lies in a range of values ​​between any two of the above.

[0112] In the present application, “the longer base of the projection trapezoid” refers to the longer of the two parallel bases of the projection trapezoid. As in Fig. As shown in Figure 4, the degree of the two angles formed between the leg of the first projection trapezoid and the longer base of the first projection trapezoid is α1 and α2, respectively. The degree of the two angles formed between the leg of the second projection trapezoid and the longer base of the second projection trapezoid is β1 and β2, respectively.

[0113] The two angles formed between the leg of the first projection trapezoid and the longer base of the first projection trapezoid, and / or the two angles formed between the leg of the second projection trapezoid and the longer base of the second projection trapezoid, lie within the aforementioned range. This optimizes the stress distribution while mitigating the effects of excessive angles on the coating area of ​​the active material, thereby ensuring the battery's energy density.

[0114] In some embodiments, the edge region of the positive electrode sheet is also provided with a chamfer.

[0115] If the edge of the positive electrode sheet is not chamfered, then no cutting processes are required for the positive electrode sheet. This avoids the problem of burr formation on the positive electrode current collector or the detachment of the active material during cutting, which could directly expose the positive electrode current collector to the electrolyte solution. However, the lack of a chamfer on the edge of the positive electrode sheet, in conjunction with the chamfer on the edge of the negative electrode sheet, limits the dimensions of the positive electrode sheet. This is to prevent the right angles at the edge of the positive electrode sheet from extending beyond the boundary of the negative electrode sheet, which could lead to lithium plating or puncture of the separator and thus a short circuit. Consequently, a significant area is lost.By positioning the chamfer at the edge of the positive electrode sheet, not only are the stresses at the corners of the electrode sheet further reduced, but the dimensions of the positive electrode sheet are also improved. This maximizes the overlap area with the projection of the negative electrode sheet, thereby increasing the energy density of the battery cell.

[0116] In some embodiments, the type of chamfer at the edge of the positive electrode sheet is identical to the type of chamfer at the edge of the negative electrode sheet.

[0117] The positive electrode sheet has the same type of chamfer as the negative electrode sheet, which promotes a more uniform voltage distribution and reduces lithium plating due to stresses at the edges.

[0118] In some embodiments, the edge region of the positive electrode sheet is provided with an R-chamfer, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the radius of the R-chamfer is 0.5% to 2.5% of the width of the positive electrode current collector.

[0119] The edge region of the positive electrode sheet is chamfered, with the radius of the chamfer being chosen within the aforementioned range. This design minimizes the lithium plating at the edges while maximizing the coating area, resulting in a battery with high energy density and capacity.

[0120] In some embodiments, the thickness of the negative electrode current collector is 6 µm to 10 µm.

[0121] In some embodiments, the thickness of the negative electrode current collector is optionally 6 µm, 7 µm, 8 µm, 9 µm or 10 µm, or lies in a range of values ​​between any two of these.

[0122] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the thickness of the positive electrode current collector is 12 µm to 15 µm.

[0123] In some embodiments, the thickness of the positive electrode current collector is optionally 12 µm, 13 µm, 14 µm or 15 µm, or lies in a range of values ​​between any two of these.

[0124] The thickness of the current collector within the aforementioned area serves a dual purpose: On the one hand, it increases the mechanical strength of the stacked pouch battery and improves the battery's resistance to expansion; on the other hand, it can increase the current passage area, thereby reducing the internal resistance of the electrode sheet and suppressing internal heating within the electrode sheet, thus improving the safety and long-term lifespan of the battery.

[0125] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the length of the positive electrode current collector and / or the negative electrode current collector is 520 mm to 570 mm.

[0126] In some embodiments, the length of the positive electrode current collector and / or the negative electrode current collector is optionally 520 mm, 530 mm, 540 mm, 550 mm, 560 mm or 570 mm, or lies within a range of values ​​between any two of the above.

[0127] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, wherein the width of the positive electrode current collector and / or the negative electrode current collector is 100 mm to 130 mm.

[0128] In some embodiments, the width of the positive electrode current collector and / or the negative electrode current collector is optionally 100 mm, 110 mm, 120 mm or 130 mm, or lies within a range of values ​​between any two of these.

[0129] The length and width of the positive electrode current collector and / or the negative electrode current collector within the aforementioned range serve, on the one hand, to improve heat dissipation and extend the battery's cycle life. On the other hand, the battery cell, which has a current collector of the aforementioned dimensions, can be adapted to the available space in the module or battery pack, thereby improving grouping efficiency and facilitating higher energy density at the module and battery pack level. [Positive electrode sheet]

[0130] 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 polymer material base layer and a metal layer formed on at least one surface of the polymer material 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 the polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0131] In some embodiments, the positive electrode film layer comprises a positive electrode active material. The positive electrode active material can be a positive electrode active material known in the art for batteries. By way of example, the positive electrode active material can comprise at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate, lithium vanadate, or lithium manganate. 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. These positive electrode active materials can be used alone or in combination with one or more of them.

[0132] In some embodiments, the positive electrode film layer optionally further comprises a conductive material. For example, the conductive material may comprise at least one of superconducting carbon, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0133] In some embodiments, the positive electrode film layer optionally further comprises a binder. For example, the binder may comprise at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0134] In some embodiments, the positive electrode sheet can be produced as follows: The components for producing the positive electrode film layer, such as the positive electrode active material, the conductive agent, the polymer binder, and any other components, are dispersed in a solvent to form a positive electrode paste; at least one side surface of the positive electrode current collector is coated with the positive electrode paste. After drying, cold pressing, and other processes, the positive electrode sheet can be obtained. [Negative electrode sheet]

[0135] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on the polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0136] In some embodiments, the negative electrode film layer optionally comprises a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0137] In some embodiments, the negative electrode film layer optionally comprises a conductive material. The conductive material can be selected from at least one of superconducting carbon, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0138] In some embodiments, the negative electrode film layer optionally also includes other excipients, such as a thickening agent (such as sodium carboxymethylcellulose (CMC-Na)).

[0139] In some embodiments, the negative electrode sheet can be produced as follows: The above-mentioned components for producing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode paste; the negative electrode paste is used to coat the negative electrode current collector, and after drying, cold pressing, and other processes, the negative electrode sheet can be obtained. [Electrolyte]

[0140] The electrolyte serves to conduct ions between the positive and negative electrode sheets. This application does not impose any specific restrictions regarding the type of electrolyte, and the type can be selected according to the requirements. For example, the electrolyte can be liquid, gel-like, or completely solid.

[0141] In some embodiments, the electrolyte is in the form of an electrolyte solution. The electrolyte solution comprises an electrolyte salt and a solvent.

[0142] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobisoxalatophosphate and lithium tetrafluoro(oxalato)phosphate.

[0143] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0144] In some embodiments, the electrolyte solution optionally includes an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive that can improve certain battery performance characteristics, such as an additive that improves the battery's overcharge behavior, an additive that improves the battery's high-temperature performance, and an additive that improves the battery's low-temperature performance. [Separator]

[0145] The present application does not impose any special restrictions on the type of separator, and any known separator with good chemical and mechanical stability and a porous structure may be used.

[0146] In some embodiments, the separator material can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film without any particular restriction. If the separator is a multi-layer composite film, the materials of each layer can be the same or different without any particular restriction. [Battery cell]

[0147] In some embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly by a stacking process.

[0148] In some embodiments, the battery cell may include an outer packaging. This outer packaging may be used to encapsulate the aforementioned electrode arrangement and the electrolyte. [Battery device]

[0149] The embodiments of the present application further provide a battery device, wherein the battery device comprises a battery cell provided by the embodiments of the present application. In some embodiments, the battery device is one or more battery modules, battery packs, or energy storage devices. [Power-consuming device]

[0150] The embodiments of the present application further provide a power-consuming device, wherein the power-consuming device comprises at least one of the battery cells, battery modules, and battery packs provided by the embodiments of the present application. The battery cell, battery module, or battery pack can be used as a power source for the power-consuming device and can also be used as an energy storage unit for the power-consuming device. The power-consuming devices can include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0151] The power-consuming device can be selected as the battery cell, battery module or battery pack, depending on its usage requirements.

[0152] Fig. Figure 5 shows an example of a power-consuming device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the power-consuming device's requirements for high performance and high energy density of the battery cell, a battery pack or battery module can be used.

[0153] The embodiments of the present application provide an energy storage device, wherein the energy storage device comprises a battery device provided by the embodiments of the present application.

[0154] Another example of a device could be a mobile phone, a tablet, a laptop, etc. This power-consuming device typically needs to be lightweight and thin, and a battery cell can be used as its power source. Example of implementation

[0155] The following are exemplary embodiments of the present application. These embodiments are for illustrative purposes only and 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 must be followed. All reagents and instruments used without manufacturer information are commercially available products. Example 11) Production of the positive electrode sheet

[0156] Preparation of the positive electrode film layer paste: the positive electrode active material lithium iron phosphate, the conductive carbon black, and the binder PVDF were mixed in a mass ratio of 98:1:1. The solvent NMP was added and stirred under vacuum until the system was homogeneous, thus obtaining the positive electrode film layer paste.

[0157] The paste of the positive electrode film layer was used to uniformly coat both sides of the 15 µm thick current collector made of aluminum foil, with a one-sided coating area density of 385 mg / 1540.25 mm². 2 After air drying at room temperature, the part was placed in an oven for further drying and then cold-pressed to obtain the positive electrode sheet. The density of the positive electrode film layer was 2.45 g / cm³. 3The length of the current collector made of aluminum foil was 544 mm, and its width was 120.5 mm.

[0158] In the stacking direction, the length and width of the current collector made of aluminum foil remained unchanged in the positive electrode sheet. 2) Production of the negative electrode sheet

[0159] Preparation of the negative electrode film paste: The negative electrode active material (artificial graphite), the binder (polyvinyl alcohol), and the conductive agent (SP-Li) were thoroughly milled in a ball mill in a solvent system of deionized water at a mass ratio of 90:5:5 to obtain the negative electrode paste. The OI value of the negative electrode active material (artificial graphite) was 5.

[0160] The paste of the negative electrode film layer was used to uniformly coat both sides of an 8 µm thick copper foil current collector, with a one-sided coating area density of 180 mg / 1540.25 mm². 2 After overnight vacuum drying at 110 °C, the material underwent a cold-pressing and chamfering process to produce the negative electrode sheet, with a compaction density of the negative electrode film layer of 1.53 g / cm³. 3 The length of the copper foil current collector was 548 mm, its width 122 mm; the chamfering process involved cutting off the four corners of the cold-pressed negative electrode sheet to form an R-chamfer, with the chamfer radius being 1.5% of the width of the negative electrode current collector.

[0161] In the stacking direction, the length and width of the copper foil current collector in the negative electrode sheet remained unchanged. 3) Production of the separator

[0162] A polyethylene film with a thickness of 11 µm was used as a separator. 4) Preparation of the electrolyte solution

[0163] Lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) were dissolved in ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 to form a homogeneous solution. This yielded an electrolyte solution with a LiPF6 concentration of 0.7 mol / L and a LiFSI concentration of 0.3 mol / L. 5) Battery installation

[0164] The positive and negative electrode sheets obtained by cutting were stacked using the Z-stacking method. The stacking sequence was "positive electrode sheet - separator - negative electrode sheet - separator," forming the electrode assembly. The baked electrode assembly was then placed in an aluminum-plastic foil, filled with electrolyte, vacuum-sealed, and thermally sealed to create an airtight seal. This process ultimately resulted in the stacked pouch battery cell, with the electrolyte fill coefficient of the battery cell being 2.5 g / Ah and the CB value being 1.05.

[0165] The manufacturing process of embodiment 2 was essentially identical to that of embodiment 1, with the difference that the one-sided coating area density of the negative electrode paste was adjusted during the production of the negative electrode sheet. Both surfaces of the 8 µm thick copper foil were coated with the negative electrode paste with a one-sided coating area density of 170 mg / 1540.25 mm². 2 coated.

[0166] The manufacturing process of embodiment 3 was essentially identical to that of embodiment 1, with the difference that the one-sided coating area density of the negative electrode paste was adjusted during the production of the negative electrode sheet. Both surfaces of the 8 µm thick copper foil were coated with the negative electrode paste to a one-sided coating area density of 200 mg / 1540.25 mm². 2 coated.

[0167] The manufacturing process of embodiment 4 was essentially identical to that of embodiment 1, with the difference that in the production of the negative electrode sheet, the compaction density of the cold-pressed negative electrode sheet was increased to 1.46 g / cm³ by modifying the pressure, the calender speed, the roller gap, the pressure holding time and the number of calender passes in the compaction process. 3 was discontinued.

[0168] The manufacturing process of embodiment 5 was essentially identical to that of embodiment 1, with the difference that in the production of the negative electrode sheet, the compaction density of the cold-pressed negative electrode sheet was increased to 1.69 g / cm³ by modifying the pressure, the calender speed, the roll gap, the pressure holding time and the number of calender passes in the compaction process. 3 was discontinued.

[0169] The manufacturing process of embodiment 6 was essentially identical to that of embodiment 1, with the difference that the type of chamfer of the negative electrode sheet was adapted. In the manufacture of the negative electrode sheet, the chamfering process comprised cutting off the four corners of the cold-pressed negative electrode sheet to form a C-chamfer, the cutting dimension being 1.5% of the width of the negative electrode current collector.

[0170] The manufacturing process of embodiment 7 was essentially identical to that of embodiment 1, with the difference that the chamfer radius of the negative electrode current collector was adjusted during the manufacture of the negative electrode sheet. The chamfer radius was set to 0.5% of the width of the negative electrode current collector.

[0171] The manufacturing process of embodiment 8 was essentially identical to that of embodiment 1, with the difference that the chamfer radius of the negative electrode current collector was adjusted during the manufacturing of the negative electrode sheet. The chamfer radius was set to 0.8% of the width of the negative electrode current collector.

[0172] The manufacturing process of embodiment 9 was essentially identical to that of embodiment 1, with the difference that the chamfer radius of the negative electrode current collector was adjusted during the manufacturing of the negative electrode sheet. The chamfer radius was set to 2% of the width of the negative electrode current collector.

[0173] The manufacturing process of embodiment 10 was essentially identical to that of embodiment 1, with the difference that a chamfering process was carried out after cold pressing of the positive electrode sheet. The chamfering process comprised cutting off the four corners of the cold-pressed positive electrode sheet to form an R-chamfer, the chamfer radius being 2.5% of the width of the positive electrode current collector.

[0174] The manufacturing process of embodiment 11 was essentially identical to that of embodiment 1, with the difference that the type of graphite used in the manufacturing process of the negative electrode sheet was adapted and the OI value of the negative electrode active material, i.e. the artificial graphite, was 1.7.

[0175] The manufacturing process of embodiment 12 was essentially identical to that of embodiment 1, with the difference that the type of graphite used in the manufacturing process of the negative electrode sheet was adapted and the OI value of the negative electrode active material, i.e. the artificial graphite, was 2.5.

[0176] The manufacturing process of embodiment 13 was essentially identical to that of embodiment 1, with the difference that the type of graphite used in the manufacturing process of the negative electrode sheet was adapted and the OI value of the negative electrode active material, i.e. the artificial graphite, was 2.95.

[0177] The manufacturing process of embodiment 14 was essentially identical to that of embodiment 1, with the difference that the type of graphite used in the manufacturing process of the negative electrode sheet was adapted and the OI value of the negative electrode active material, i.e. the artificial graphite, was 3.5.

[0178] The manufacturing process of embodiment 15 was essentially identical to that of embodiment 1, with the difference that the electrolyte filling coefficient was adjusted during battery assembly and the electrolyte filling coefficient of the battery cell was 2.7 g / Ah.

[0179] The manufacturing process of embodiment 16 was essentially identical to that of embodiment 1, with the difference that the electrolyte filling coefficient was adjusted during battery assembly and the electrolyte filling coefficient of the battery cell was 3 g / Ah.

[0180] The manufacturing process of embodiment 17 was essentially identical to that of embodiment 1, with the difference that the electrolyte filling coefficient was adjusted during battery assembly and the electrolyte filling coefficient of the battery cell was 3.2 g / Ah.

[0181] The manufacturing process of embodiment 18 was essentially identical to that of embodiment 1, with the difference that the electrolyte filling coefficient was adjusted during battery assembly and the electrolyte filling coefficient of the battery cell was 4 g / Ah.

[0182] The manufacturing process of embodiment 19 was essentially identical to that of embodiment 1, with the difference that the dimensions of the current collector were adjusted during the manufacturing process of the negative and positive electrode sheets. In the stacking direction of the electrode sheets in the electrode assembly, the dimensions of the negative electrode current collector decreased sequentially by 22 µm in both the longitudinal and lateral directions. In the stacking direction of the electrode sheets in the electrode assembly, the dimensions of the positive electrode current collector decreased sequentially by 22 µm in both the longitudinal and lateral directions.

[0183] The manufacturing process of embodiment 20 was essentially identical to that of embodiment 1, with the difference that the dimensions of the current collector were adjusted during the manufacturing process of the negative and positive electrode sheets. In the stacking direction of the electrode sheets in the electrode assembly, the dimensions of the negative electrode current collector decreased sequentially by 91 µm in both the longitudinal and lateral directions. Similarly, in the stacking direction of the electrode sheets in the electrode assembly, the dimensions of the positive electrode current collector decreased sequentially by 91 µm in both the longitudinal and lateral directions.

[0184] The manufacturing process of comparative example 1 was essentially identical to that of embodiment 1, with the difference that the production of the positive electrode sheet and the production of the negative electrode sheet did not include a chamfering process.

[0185] The manufacturing process of comparative example 2 was essentially identical to that of embodiment 1, with the difference that in the manufacture of both the positive electrode sheet and the negative electrode sheet, the chamfering process was only applied to the negative electrode sheet in the longitudinal direction of the electrode arrangement and at the end furthest from the electrode tab.

[0186] The manufacturing process of comparative example 3 was essentially identical to that of embodiment 1, with the difference that the one-sided coating area density of the negative electrode paste was adjusted during the production of the negative electrode sheet. Both surfaces of the 8 µm thick copper foil were coated on both sides with the negative electrode paste, achieving a one-sided coating area density of 155 mg / 1540.25 mm². 2 coated.

[0187] The manufacturing process of comparative example 4 was essentially identical to that of embodiment 1, with the difference that the one-sided coating area density of the negative electrode paste was adjusted during the production of the negative electrode sheet. Both surfaces of the 8 µm thick copper foil were coated with the negative electrode paste with a one-sided coating area density of 220 mg / 1540.25 mm². 2 coated.

[0188] The manufacturing process of comparative example 5 was essentially identical to that of embodiment 1, with the difference that in the production of the negative electrode sheet, the compaction density of the cold-pressed negative electrode sheet was increased to 1.33 g / cm³ by modifying the pressure, the calender speed, the roll gap, the pressure holding time and the number of calender passes in the compaction process. 3 was discontinued.

[0189] The manufacturing process of comparative example 6 was essentially identical to that of embodiment 1, with the difference that in the production of the negative electrode sheet, the compaction density of the cold-pressed negative electrode sheet was increased to 1.80 g / cm³ by modifying the pressure, the calender speed, the roller gap, the pressure holding time and the number of calender passes in the compaction process. 3 was discontinued. Performance tests 1. Examination of the OI value

[0190] In the present application, the OI value could be tested using an X-ray diffractometer (such as the Bruker D8 Discover) in accordance with JISK 0131-1996 and JB / T 4220-2011. This yielded the X-ray diffraction pattern of the negative electrode film layer, from which the OI value of the negative electrode film layer could be determined as OI = I 004 / I 110 was calculated. 004 was the integral surface of the diffraction peak corresponding to the 004 crystal plane of crystalline carbon in the negative electrode film layer, and I 110The integral surface of the diffraction peak corresponding to the 110° crystal plane of crystalline carbon in the negative electrode film layer was given by [equation missing]. In the X-ray diffraction analysis of the present application, a copper target can be used as the anode target, with CuKα radiation being used as the source. The radiation wavelength is 1.5418 Å, with a 2θ-angle scan range of 20° to 80° and a scan rate of 4° / min. 2. Test method for the energy density of the battery

[0191] The battery cells produced in the individual embodiments and comparative examples were allowed to rest for 2 hours at 25 °C to ensure that the battery cell temperature was 25 °C. At 25 °C, the battery cell was charged at 1 / 3 C to the final charging voltage of 3.75 V and continued charging at constant voltage until the current reached 0.05 C and the charging was terminated (where C represented the nominal capacity of the battery cell). The battery cell was allowed to rest for 1 hour at 25 °C and then discharged at 0.33 C to the final discharge voltage of 2.0 V at 25 °C. The total discharge energy of the battery cell was recorded as E0.

[0192] The volume of the battery cell was measured as V0 in L.

[0193] The volume energy density of the battery cell = discharge energy E0 of the battery cell / volume V0 of the battery cell, expressed in the unit Wh / L. 3. Cycle performance test method

[0194] At 25 °C, battery cells manufactured according to the individual embodiments and comparative examples were charged to 50% state of charge (SOC) at a constant current of 1 C. They were then charged to 80% SOC at 0.87 C, then to the final charging voltage of 3.75 V at 0.33 C, and further charged at the final charging voltage at a constant voltage until the current reached 0.05 C. The battery cells were then discharged to a final discharge voltage of 2.0 V at a constant current of 1 C, constituting one charge and discharge cycle. The discharge capacity of the battery cell at this point was recorded as the discharge capacity E1 of the first battery cycle. This charge and discharge cycle was repeated 1000 times, and the discharge capacity of the battery cell at this point was recorded as E2. Cycle life after 1000 cycles = E2 / E1 × 100%. 4. Test method for the discharge K-value

[0195] After the cycle, the cell was left to rest for 2 hours at 25 °C. It was then charged to 3.75 V with a constant current of 0.33 C, followed by a constant voltage charge until the charging current dropped below 0.05 C. At this point, the charging process was terminated. After 2 hours of standby, OCV1 was recorded in mV; after 24 hours, the voltage was checked and recorded as OCV2 in mV; K-value = (OCV1 - OCV2) / 24 hours, expressed in mV / h.

[0196] The battery cells for each embodiment and comparison example were manufactured according to the methods described above. The specific parameters and performance characteristics are detailed in Tables 1 and 2 below. Table 1 Negative electrode film layer chamfer Surface density (mg / 1540.25 mm²) 2 ) Completely discharged state Compaction density (g / cm³) 3 ) One-sided thicknessµm type Dimension(%) Energy density (Wh / L) Discharge K-value per cycle (mV / h) Example of implementation 11 180 1,45 82,8 R-type 1,5 480 0,050 Example of implementation 12 170 1,45 76,1 R-type 1,5 465 0,038 Example of implementation 13 200 1,45 89,6 R-type 1,5 503 0,055 Example of implementation 14 180 1,4 85,8 R-type 1,5 470 0,036 Example of implementation 15 180 1,6 75,1 R-type 1,5 494 0,058 Example of implementation 16 180 1,45 82,8 C-type 1,5 480 0,056 Example of implementation 17 180 1,45 82,8 R-type 0,5 481 0,078 Example of implementation 18 180 1,45 82,8 R-type 0,8 480 0,066 Example of implementation 19 180 1,45 82,8 R-type 2 479 0,040 Example of implementation 110 180 1,45 82,8 R-type 2,5 478 0,030 Comparative example 1 180 1,45 82,8 / / 486 0,180 Comparative example 2 180 1,45 82,8 R-type (partially) 1,5 483 0,110 Comparative example 3 155 1,45 69,4 R-type 1,5 436 0,033 Comparative example 4 220 1,45 98,5 R-type 1,5 518 0,073 Comparative example 5 180 1,3 92,4 R-type 1,5 452 0,032 Comparative example 6 180 1,7 70,7 R-type 1,5 506 0,078

[0197] By comparing the embodiments and the comparative examples, it is evident that the battery cell of the present application comprises an electrode arrangement, an electrolyte solution, and a housing body, wherein the electrode arrangement is received in the housing body and the housing body is made of a pouch material; and wherein the electrode arrangement comprises a positive electrode sheet, a negative electrode sheet, and a separator, wherein the positive electrode sheet and the negative electrode sheet are arranged stacked alternately, the separator being arranged between the positive electrode sheet and the negative electrode sheet, which are adjacent to each other; wherein the edge region of the negative electrode sheet is provided with a chamfer;wherein the projection of the positive electrode sheet in the stacking direction of the electrode sheet falls completely within the projection of the adjacent negative electrode sheet in the stacking direction of the electrode sheet; and wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector; wherein, in the fully discharged state, the one-sided coating areal density of the negative electrode film layer is 170 mg / 1540.25 mm²; 2 up to 200 mg / 1540.25 mm 2 is, and the compaction density is 1.4 g / cm³ 3 up to 1.6 g / cm³ 3 A higher energy density combined with a low discharge K-value after cycle indicates a reduction in lithium plating during the battery cycle process.

[0198] A comparison between embodiment 1 and embodiment 6 shows that both the C-phase and the R-phase serve to reduce lithium plating. The R-phase exhibits a superior voltage distribution, resulting in a lower K-value after a cycle.

[0199] By comparing embodiment 1 with embodiments 7 to 9 and embodiment 10, it is evident that by setting the radius of the R-phase to 0.5% to 2.5% of the width of the negative electrode sheet and further to 0.8% to 2%, a balance is achieved between maximizing the energy density of the battery and suppressing lithium plating. Table 2 CB value OI value Electrolyte filling coefficient (g / Ah) α1 = α2(°) β1 = β2(°) Energy density (Wh / L) Cycle life after 1000 cycles (%) K-value per cycle Example 1 1,08 5 2,5 90 90 480 91,5 0,050 Example 2 1,05 5 2,5 90 90 465 92,8 0,038 Example 3 1,15 5 2,5 90 90 503 90,3 0,055 Example 11 1,08 1,7 2,5 90 90 470 90,2 0,037 Example 12 1,08 2,5 2,5 90 90 472 90,5 0,039 Example 13 1,08 2,95 2,5 90 90 475 90,8 0,042 Example 14 1,08 3,5 2,5 90 90 478 91,3 0,045 Example 15 1,08 5 2,7 90 90 478 91,8 0,042 Example 16 1,08 5 3 90 90 475 92,1 0,035 Example 17 1,08 5 3,2 90 90 473 92,3 0,034 Example 18 1,08 5 4 90 90 466 91,6 0,047 Example 19 1,08 5 2,5 70 70 460 92,1 0,034 Example 20 1,08 5 2,5 85 85 470 91,7 0,039

[0200] A comparison between embodiments 1 to 3 shows that with a CB value of the battery cell in the range of 1.05 to 1.15, and especially in the range of 1.08 to 1.15, the lithium plating is reduced during the cycle process. The K value after a cycle is lower, and the battery cell exhibits a higher cycle life and energy density.

[0201] By comparing embodiment 1 with embodiments 11 to 14, it is evident that an OI value of the graphite material of 1.7 to 5 and in particular of 2.5 to 3.5 is advantageous for improving the energy density and cycle performance of the battery.

[0202] By comparing embodiment 1 with embodiments 15 to 18, it is evident that with an electrolyte filling coefficient of the battery cell of 2.5 g / Ah to 4 g / Ah and in particular of 2.7 g / Ah to 3.2 g / Ah, the cycle performance of the battery is improved while maintaining a high energy density.

[0203] By comparing embodiment 1 with embodiments 19 and 20, it can be seen that in the stacking direction of the electrode sheet in the electrode arrangement, the length and width dimensions of the positive electrode current collector decrease independently of each other sequentially, where 70° ≤ α1 ≤ 85°, 70° ≤ α2 ≤ 85° applies, and the length and width dimensions of the negative electrode current collector decrease independently of each other sequentially, where 70° ≤ β1 ≤ 85° and 70° ≤ β2 ≤ 85° applies, which further reduces the lithium plating degree and the K-value after a cycle.

[0204] It should be noted that the present application is not limited to the embodiments mentioned above. The above embodiments are merely examples, and all embodiments that exhibit essentially the same structure and effect as the technical idea within the technical solution of the present application are all included within the technical scope of the present application. Furthermore, other possibilities in which various modifications conceivable to a person skilled in the art are added to the embodiments, and some components of the embodiments are combined to form other embodiments, are also included within the scope of the present application without departing from the core of the present application.

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