Battery cell, battery device, electrical device

Abstract

Battery cell, including: a case; and an electrode assembly located inside the housing, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separator film, the separator film being arranged between the positive and the negative electrode plates, where The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector. The negative electrode film layer comprises an active material of the negative electrode. The negative electrode film layer comprises a first negative electrode film layer located away from the negative electrode current collector and a second negative electrode film layer located near the negative electrode current collector. The first negative electrode film layer comprises a first active material of the negative electrode, and the second negative electrode film layer comprises a second active material of the negative electrode.The first active material of the negative electrode contains a silicon-based material and a carbon-based material, the second active material of the negative electrode contains a carbon-based material, and the mass fraction of the silicon element in the negative electrode film layer is 0.5% to 6%. The separator film comprises a base film, a first porous coating on the side of the base film facing the negative electrode plate, and a second porous coating on the side of the base film facing the positive electrode plate. Both the first and second porous coatings contain filler particles.

Description

AREA OF INVENTION

[0001] The present disclosure relates to a battery cell, a battery device and an electrical device. STATE OF THE ART

[0002] Battery cells are characterized by high capacity, long lifespan, and other properties, and have found widespread use in recent years. Due to significant advances in battery technology, the performance requirements for battery cells have increased. However, the performance of battery cells at low temperatures is currently still limited. REVELATION OF THE INVENTION

[0003] This disclosure provides a battery cell, a battery device and an electrical device, wherein the battery cell exhibits both good performance at low temperatures and low state of charge (SOC) as well as good cycle performance at low temperatures.

[0004] In a first aspect, this disclosure provides a battery cell comprising a housing and an electrode assembly. The electrode assembly is located inside the housing and includes a positive electrode plate, a negative electrode plate, and a separator film. The separator film is positioned between the positive and negative electrode plates. The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector. The negative electrode film layer comprises a negative electrode active material. The negative electrode film layer includes a first negative electrode film layer located away from the negative electrode current collector and a second negative electrode film layer located near the negative electrode current collector.The first negative electrode film layer comprises a first active material of the negative electrode, and the second negative electrode film layer comprises a second active material of the negative electrode. The first active material of the negative electrode contains a first silicon-based material and a first carbon-based material; the second active material of the negative electrode contains a second carbon-based material, and the mass fraction of the silicon element in the negative electrode film layer is 0.5% to 6%. The separator film comprises a base film, a first porous coating on the side of the base film facing the negative electrode plate, and a second porous coating on the side of the base film facing the positive electrode plate. Both the first and second porous coatings contain filler particles.

[0005] Compared to carbon-based materials, silicon-based materials typically exhibit lower electronic conductivity. Therefore, by incorporating the first silicon-based and the first carbon-based material into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a mass fraction of at least 0.5% of the silicon element in the negative electrode film layer, the internal ohmic resistance at the interface between the positive and negative electrode plates can be increased. Consequently, this configuration allows the first negative electrode film layer to rapidly heat the negative electrode plate and the battery cell during low-temperature discharge. The reaction kinetics of a battery cell are temperature-dependent.As the temperature of the negative electrode plate and the battery cell increases, the reaction kinetics of the battery cell improves at low temperatures.

[0006] Compared to carbon-based materials, silicon-based materials exhibit a greater volume expansion. Therefore, by incorporating the first silicon-based and the first carbon-based materials into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a mass fraction of at least 0.5% of the silicon element in the negative electrode film layer, the volume expansion of the negative electrode can be increased. This results in the negative and positive electrode plates being positioned closer together in a low-temperature environment. The reaction kinetics of a battery cell are related to the contact pressure of the internal interfaces within the electrode plates.The closer the negative and positive electrode plates are to each other, the smaller the gap between them, the lower the interfacial resistance of the battery cell, and the better the wettability of the electrode plates by the electrolyte. This leads to a higher electrochemical reaction rate of the electrode plates and thus improves the reaction kinetics of the battery cell at low temperatures.

[0007] Compared to carbon-based materials, silicon-based materials exhibit a higher lithium intercalation potential and are less prone to lithium deposition at the negative electrode at low temperatures. Therefore, by incorporating the first silicon-based and the first carbon-based materials into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a silicon element mass fraction of at least 0.5% in the negative electrode film layer, the problem of lithium deposition at the negative electrode during low-temperature charging can be reduced.

[0008] Simultaneously, the mass fraction of the silicon element in the negative electrode film layer must not exceed 6%. If the mass fraction of the silicon element in the negative electrode film layer is too high, this leads to excessive volume expansion of the negative electrode, which impairs the wettability of the electrode assembly by the electrolyte, as well as the charging and discharging behavior of the battery cell and the performance of the battery cell at low temperatures and low states of charge (SOC).

[0009] The present disclosure provides for the application of a first porous coating and a second porous coating containing filler particles to both sides of the base film. Since the filler particles themselves exhibit a certain toughness, when arranged on both sides of the base film, they can reduce the shrinkage behavior of the base film at low temperatures, resulting in a larger pore size and higher porosity of the separator film at low temperatures. Consequently, the through-resistance for lithium ions during discharge of the battery cell at low temperatures can be reduced, improving the performance of the battery cell at low temperatures and low states of charge (SOC). Furthermore, the filler particles exhibit high mechanical strength.Their arrangement on both sides of the base film can increase the mechanical strength and puncture resistance of the separator film and also help to reduce mechanical micro-short circuits. Compared to the base film, the filler particles exhibit a higher electrolyte affinity, which improves the wettability of the separator film by the electrolyte and increases the lithium-ion conductivity of the separator film. Simultaneously, the first and second porous coatings can store electrolyte, increasing the separator film's electrolyte retention capacity. This ensures that an electrolyte-filled salt bridge forms between the positive and negative electrode plates, which in turn enhances the transport kinetics of lithium ions during the battery cell's discharge process at low temperatures.

[0010] Therefore, this revelation, through the matching of the negative electrode and the separator film of the battery cell, enables the battery cell to exhibit good performance at low temperatures and low state of charge (SOC), as well as good cycle performance at low temperatures.

[0011] In some embodiments, the thickness of the first porous coating is 0.5µm to 2 µm.

[0012] In some embodiments, the thickness of the second porous coating is 0.5 µm to 2 µm.

[0013] In some embodiments, the filler particles comprise one or more of the following substances: inorganic particles, organic particles, and organic-inorganic composite particles.

[0014] In some embodiments, the volumetric distribution particle diameter Dv50 of the filler particles is 0.2 µm to 0.8 µm.

[0015] In some embodiments, the filler particles have a porous structure. Porous filler particles exhibit a higher electrolyte affinity, which improves the wettability of the separator film by the electrolyte and increases the lithium-ion conductivity of the separator film. Simultaneously, the porous structure of the filler particles allows them to retain electrolyte, thus increasing the separator film's electrolyte retention capacity. This ensures the formation of an electrolyte-filled salt bridge between the positive and negative electrode plates, which in turn enhances the lithium-ion transport kinetics during low-temperature battery cell discharge and optimizes its low-temperature, low-state-of-charge (SOC) performance, as well as its low-temperature cycle performance.

[0016] In some embodiments, the specific surface area of ​​the filler particles is 10 m². 2 / g up to 1500 m 2 / G.

[0017] In some embodiments, the inorganic particles comprise one or more of the following substances: aluminum oxide, silicon dioxide, zirconium dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, silicon carbide, magnesium carbide, molecular sieve, zeolite and Prussian blue.

[0018] In some embodiments, the organic particles comprise polymer particles.

[0019] In some embodiments, the organic-inorganic composite particles comprise one or more of the following materials: covalent organic framework materials and metal-organic framework materials.

[0020] In some embodiments, the filler particles comprise inorganic particles, and the inorganic particles are aggregates of primary particles.

[0021] In some embodiments, the separator film further comprises an adhesive layer. The adhesive layer comprises polymer binder particles and is arranged on at least parts of the surface of the first porous coating and / or the second porous coating that face away from the base film.

[0022] Polymer binder particles have a binding property that enables a firm connection of the electrode plates, reduces the gap between the electrode plates, improves the wettability of the electrode plates by the electrolyte, and improves the cycle performance of the battery cells at low temperatures.

[0023] In some embodiments, the polymer binder particles comprise one or more of the following substances: vinylidene fluoride polymer particles and acrylate copolymer particles.

[0024] In some embodiments, the volumetric distribution particle diameter Dv50 of the polymer binder particles is 2 µm to 8 µm.

[0025] In some embodiments, the thickness of the base film is 5 µm to 10 µm.

[0026] In some embodiments, the thickness of the separator film is 7 µm to 14 µm.

[0027] In some embodiments, the porosity of the separator film at 25 °C is 40% to 60% and the porosity of the separator film at -25 °C is 10% to 35%.

[0028] In some embodiments, the mass fraction of the Si element in the negative electrode film layer is 1.5% to 5%.

[0029] In some embodiments, the volumetric particle size distribution diameter Dv10 of the active material of the negative electrode is 4 µm to 8 µm.

[0030] In some embodiments, the volumetric particle size distribution diameter Dv50 of the active material of the negative electrode is 10 µm to 25 µm.

[0031] In some embodiments, the volumetric particle size distribution diameter Dv90 of the active material of the negative electrode is 25 µm to 40 µm.

[0032] The active material of the negative electrode has a suitable particle size, resulting in a rapid solid-state diffusion rate of lithium ions and lower concentration polarization. This improves the reaction kinetics of the battery cell at low temperatures.

[0033] In some embodiments, the specific surface area of ​​the active material of the negative electrode is 3 m². 2 / g up to 7 m 2 / G.

[0034] In some embodiments, the first carbon-based material comprises one or more of the following substances: synthetic graphite, natural graphite.

[0035] In some embodiments, the first carbon-based material comprises synthetic graphite, and the surface of the synthetic graphite has a carbon coating. Synthetic graphite possesses a high specific capacity. Coating it with a carbon layer allows surface defects to be modified and the energy density of the battery cells to be improved. The carbon layer consists of soft and / or hard carbon, which forms three-dimensional ion channels. The carbon layer improves the kinetics of the synthetic graphite and thus also the kinetics of the battery cells. Furthermore, the carbon layer reduces the volume change of the synthetic graphite and decreases side reactions between the synthetic graphite and the electrolyte, resulting in the formation of a higher-quality SEI film.This reduces the loss of active lithium and electrolyte through the repair of SEI film damage and ultimately improves the cycle performance of the battery cells.

[0036] In some embodiments, the degree of graphitization of the first carbon-based material is between 90% and 96%. If the degree of graphitization of the first carbon-based material is within the aforementioned range, it exhibits both a high specific capacity and good ion transport performance, which is advantageous for the battery cell in order to achieve both high energy density and good reaction kinetics at low temperatures.

[0037] In some embodiments, the OI value of the first carbon-based material powder ranges from 0.8 to 1.7. This first carbon-based material exhibits a low OI value and lithium ion intercalation sites oriented in all particle directions. This facilitates the rapid uptake of lithium ions from the positive electrode, thus improving the battery cell's kinetics. Simultaneously, the first carbon-based material is characterized by high isotropy, which better distributes the volume expansion caused by lithium ion intercalation. This also leads to the formation of a higher-quality SEI film, reduces the loss of active lithium and electrolyte through SEI film repair, and thus improves the battery cell's cycle performance.

[0038] In some embodiments, the second carbon-based material comprises one or more of the following substances: synthetic graphite, natural graphite.

[0039] In some embodiments, the degree of graphitization of the second carbon-based material is between 90% and 96%. If the degree of graphitization of the second carbon-based material is within the aforementioned range, it exhibits both high specific capacity and good ion transport performance, which is advantageous for the battery cell in order to achieve both high energy density and good reaction kinetics at low temperatures.

[0040] In some embodiments, the OI value of the second carbon-based material powder ranges from 0.8 to 1.7. This second carbon-based material exhibits a low OI value and lithium ion intercalation sites oriented in all particle directions. This facilitates the rapid uptake of lithium ions from the positive electrode, thus improving the battery cell's kinetics. Simultaneously, this second carbon-based material is characterized by high isotropy, which better distributes the volume expansion caused by lithium ion intercalation. This also leads to the formation of a higher-quality SEI film, reduces the loss of active lithium and electrolyte through SEI film repair, and thus improves the battery cell's cycle performance.

[0041] In some embodiments, the first silicon-based material comprises one or more of the following substances: elemental silicon, silicon-carbon material, silicon oxides, silicon nitrides, and silicon alloys.

[0042] In some embodiments, the second active material of the negative electrode further comprises a second silicon-based material.

[0043] In some embodiments, the mass fraction of the silicon element in the first negative electrode film layer is greater than the mass fraction of the silicon element in the second negative electrode film layer. Compared to carbon-based materials, silicon-based materials exhibit a higher lithium intercalation potential and are less prone to lithium deposition at low temperatures. The first negative electrode film layer is located in the surface region, the second in the bottom region. A high mass fraction of the silicon element in the surface region reduces lithium deposition at low temperatures on the negative electrode. A low mass fraction of the silicon element in the bottom region minimizes damage to the conductive network of the negative electrode film layer caused by the volume expansion of the silicon-based material, thus improving the charging and discharging performance of the battery cell.

[0044] In some embodiments, the specific surface area of ​​the negative electrode film layer is 0.5 m². 2 / g up to 2 m 2 / G.

[0045] In some embodiments, the porosity of the negative electrode film layer is 20% to 30%.

[0046] In some embodiments, the OI value of the negative electrode film layer is 5 to 10. If the OI value of the negative electrode film layer is within the aforementioned range, this is advantageous for improving the lithium ion intercalation performance of the negative electrode film layer, which in turn promotes the improvement of the reaction kinetics of the battery cell at low temperatures.

[0047] In some embodiments, the compaction density of the negative electrode film layer is 1.4 g / cm³. 3 up to 1.7 g / cm³ 3By maintaining the density of the negative electrode film layer within the aforementioned range, the battery cell can exhibit both high energy density and good performance at low temperatures and low states of charge (SOC).

[0048] In some embodiments, the thickness of the negative electrode film layer is 90 µm to 150 µm. By maintaining the thickness of the negative electrode film layer within the aforementioned range, the battery cell can exhibit both high energy density and good performance at low temperatures and low states of charge (SOC).

[0049] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer ranges from 5:95 to 50:50. The first negative electrode film layer exhibits high volumetric expansion and high resistance. By maintaining the thickness ratio of the first to the second negative electrode film layer within the aforementioned range, the operating temperature of the battery cell can be increased, the gap between the electrode plates reduced, and good electrolyte wettability and electrolyte retention of the negative electrode plates and the separator film achieved. This results in good performance at low temperatures and low states of charge (SOC), as well as good cycle performance at low temperatures.

[0050] In some embodiments, the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector. The positive electrode film layer comprises an active material of the positive electrode. The active material of the positive electrode comprises a lithium transition metal oxide. This lithium transition metal oxide contains nickel, the molar fraction of which among the transition metal elements in the lithium transition metal oxide is more than 80%.

[0051] Optionally, the lithium transition metal oxide contains nickel, with the molar fraction of the Ni element in the transition metal elements in the lithium transition metal oxide being more than 85%.

[0052] This allows the battery cell to have a high energy density.

[0053] In some embodiments, the lithium transition metal oxide comprises single-crystal lithium transition metal oxide, wherein the total area of ​​the single-crystal lithium transition metal oxide is 60% to 100% of the total area of ​​the active material of the positive electrode.

[0054] In some embodiments, the volumetric particle size distribution diameter Dv10 of the active material of the positive electrode is 0.5 µm to 2.5 µm.

[0055] In some embodiments, the volumetric particle size distribution diameter Dv50 of the active material of the positive electrode is 2 µm to 6 µm.

[0056] In some embodiments, the volumetric particle size distribution diameter Dv90 of the active material of the positive electrode is 5 µm to 8 µm.

[0057] The active material of the positive electrode has a suitable particle size, resulting in a rapid solid-state diffusion rate of lithium ions and lower concentration polarization. This improves the reaction kinetics of the battery cell at low temperatures.

[0058] In some embodiments, the specific surface area of ​​the positive electrode film layer is 0.7 m². 2 / g up to 2 m 2 / G.

[0059] In some embodiments, the compaction density of the positive electrode film layer is 3.4 g / cm³. 3 up to 3.7 g / cm³ 3 .

[0060] In some embodiments, the lithium transition metal oxide comprises the elements Ni and Co, wherein the Co content in the surface region of the lithium transition metal oxide is higher than the Co content in the core region of the lithium transition metal oxide; or the lithium transition metal oxide comprises the elements Ni and Mn, wherein the Mn content in the surface region of the lithium transition metal oxide is lower than the Mn content in the core region of the lithium transition metal oxide;or the lithium transition metal oxide comprises the elements Ni, Co and Mn, wherein the Co content in the surface region of the lithium transition metal oxide is higher than the Co content in the core region of the lithium transition metal oxide and the Mn content in the surface region of the lithium transition metal oxide is lower than the Mn content in the core region of the lithium transition metal oxide, wherein the surface region of the lithium transition metal oxide is a region extending radially 100 nm inwards from the outermost surface of the particle, and the core region of the lithium transition metal oxide is a region extending radially 300 nm outwards from the center of the particle.

[0061] In some embodiments, the lithium transition metal oxide comprises Ni and dopant elements, wherein the dopant elements comprise cation and / or anion dopant elements, wherein the cation dopant elements comprise one or more of the elements Al, Y, Zr, Zn, Cr, Mg, V, Ti and B and the anion dopant elements comprise one or more of the elements N, F, S and Cl.

[0062] In some embodiments, the positive electrode film layer comprises a conductive medium of the positive electrode, wherein the mass fraction of the conductive medium of the positive electrode in the positive electrode film layer is 0.1% to 1.5%.

[0063] In some embodiments, the positive electrode film layer comprises a positive electrode conductor, wherein the positive electrode conductor comprises one or more of the following materials: carbon nanotubes, carbon black, carbon black, carbon fibers, and graphene. The carbon nanotubes comprise one or more of the following materials: single-walled, few-walled, and multi-walled carbon nanotubes.

[0064] In some embodiments, the conductive material of the positive electrode comprises carbon nanotubes, and at least a portion of the carbon nanotubes is located on the surface of the active material of the positive electrode.

[0065] In some embodiments, the aspect ratio of the carbon nanotubes is 500 to 100000.

[0066] In some embodiments, the battery cell further comprises an electrolyte, wherein the electrolyte comprises an organic solvent and an electrolyte salt, the electrolyte salt comprising lithium hexafluorophosphate (LiPF6). The organic solvent comprises ethylene carbonate and ethyl methyl carbonate.

[0067] In some embodiments, the mass ratio of ethylene carbonate to ethyl methyl carbonate is 20:80 to 70:30.

[0068] In some embodiments, the electrolyte further comprises fluoroethylene carbonate, wherein the mass of the fluoroethylene carbonate is 0.5% to 5% of the total mass of the electrolyte. FEC generates high-quality films, which contributes to the formation of a low-resistance, ion-conducting SEI film at the negative electrode. This reduces the energy barrier for the passage of lithium ions through the SEI film at low temperatures and decreases the accumulation of electrolyte side reaction products. As a result, the internal resistance of the battery cell can be reduced, and the reaction kinetics and cycle performance of the battery cell can be improved at low temperatures.

[0069] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 1 g / Ah to 2 g / Ah.

[0070] In some embodiments, the battery cell is a pouch battery cell whose housing comprises two packaging films. An electrode assembly is located between the two packaging films, and the edges of the two packaging films are joined to form a seal. The pouch battery cell also includes electrode terminals, which pass between the two packaging films and are electrically connected to the electrode assembly.

[0071] In some embodiments, the packaging film comprises an insulating protective layer, a metal layer and an insulating connecting layer, wherein the insulating connecting layer is arranged on the surface of the metal layer facing the electrode assembly and the insulating protective layer is arranged on the surface of the metal layer facing away from the electrode assembly.

[0072] In some embodiments, the battery cell is a hard-shell battery cell with a square metal casing.

[0073] In a second aspect, the present disclosure further provides a battery device comprising a plurality of battery cells according to the first aspect of the present disclosure.

[0074] In some embodiments, the battery-powered device includes the following: a housing comprising a support plate and a frame enclosing the outer perimeter of the support plate, wherein the support plate and the frame are rigidly connected to each other; Several battery cells, wherein the battery cells are pouch battery cells. The several battery cells are stacked in a first direction and housed in the casing, the surface of each battery cell comprising a first surface and a second surface, the first surface being larger than the second, the first surfaces of the several battery cells facing each other along the first direction, while the carrier plate facing the second surfaces of the several battery cells along a second direction; The housing includes at least one connecting beam extending in a third direction, wherein this connecting beam is firmly connected to the support plate and / or the frame, wherein at least one battery cell is supported along the first direction on the connecting beam, the first, second and third directions being perpendicular to each other.

[0075] In some embodiments, the battery device also includes a thermal management component and an adhesive for mounting.

[0076] The thermal management component is positioned between the carrier plate and the battery cell to regulate the temperature of the battery cell; the adhesive is positioned between the thermal management component and the battery cell to attach the battery cell to the thermal management component.

[0077] In some embodiments, the adhesive is applied directly to the battery cell housing.

[0078] In some embodiments, the battery device further comprises a receiving housing, wherein the receiving housing contains at least one battery cell, and wherein the adhesive is applied directly to the wall of the receiving housing.

[0079] In some embodiments, the nominal capacity of each battery cell is at least 100 Ah.

[0080] In a third aspect, this revelation provides an electrical device comprising a battery cell according to the first aspect of this revelation or a battery device according to the second aspect of this revelation. DESCRIPTION OF THE FIGURES

[0081] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the figures used in the embodiments of the present disclosure are briefly presented below. It is obvious that the figures described below represent only some embodiments of the present disclosure. A person skilled in the art in this field can draw further figures based on these figures without inventive step. Fig.Figure 1 shows a schematic representation of a battery-powered device provided by an exemplary embodiment. Fig. Figure 2 shows an exploded view of a battery device provided by an exemplary embodiment. Fig. Figure 3 shows an enlarged partial view of the in Fig. 2 battery devices shown. Fig. Figure 4 shows a schematic representation of an electrical device provided by some embodiments of the present disclosure. Fig. Figure 5 shows an exploded view of an electrode assembly provided by some embodiments of the present disclosure. Fig. Figure 6 shows an exploded view of an electrode assembly provided by some other embodiments of the present disclosure. Fig.Figure 7 shows an exploded view of a pouch battery cell provided by an exemplary embodiment. Fig. Figure 8 shows a scanning electron microscope image of the negative electrode plate produced in embodiment 1. Fig. Figure 9 shows a scanning electron microscope image of the separator film produced in embodiment 1.

[0082] The figures are not necessarily to scale. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0083] The embodiments of the battery cell, battery device, and electrical device of the present disclosure are described in detail below with reference to the figures. Occasionally, however, unnecessary details may be omitted. For example, detailed explanations of generally known facts or repetitions of actually identical structures may be avoided. This is intended to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Furthermore, the figures and the following description serve to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter of the claims.

[0084] The “range” disclosed in this disclosure is defined by a lower bound and an upper bound. The specified range is determined by selecting a lower bound and an upper bound, with the selected lower and upper bounds defining the limits of the respective range. The range thus defined can include or exclude limits and can be combined arbitrarily. That is, any lower bound can be combined with any upper bound to form a range. For example, if the ranges 60-120 and 80-110 are specified for a particular parameter, it is assumed that the ranges 60-110 and 80-120 are also understood. Furthermore, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4, and 5 are specified, then the following ranges are to be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.In this disclosure, unless otherwise specified, the range of values ​​“a to b” denotes an abbreviated representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the range of values ​​“0 to 5” means that all real numbers between “0 and 5” are fully listed in this application, where “0 to 5” is merely an abbreviated representation of these number combinations. Furthermore, when it is stated that a parameter is an integer ≥ 2, this means that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0085] Unless otherwise stated, all embodiments and optional embodiments of this disclosure may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure content of the present disclosure.

[0086] Unless otherwise stated, all technical features and optional technical features of this disclosure may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure content of this disclosure.

[0087] Unless otherwise stated, all steps of this disclosure may be performed sequentially or in any order, with sequential performance being preferred. For example, the method includes steps (a) and (b), which indicates that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. The method may also include step (c), for example, which means that step (c) may be added to the method in any order. Thus, for example, the method may include steps (a), (b), and (c), steps (a), (c), and (b), or steps (c), (a), and (b), and so on.

[0088] Unless otherwise stated, in this disclosure the terms “first”, “second”, etc. are used to distinguish different objects and not to describe a particular order or a relationship of superior or subordinate importance.

[0089] In this revelation, the term "several" refers to two or more.

[0090] In the description of embodiments of this disclosure, unless otherwise specified, the indication that a first feature is located "on" or "under" a second feature can mean that the first and second features are in direct contact or that the first and second features are in indirect contact via an intermediate medium. Furthermore, the indication that the first feature is located "above," "above," or "on" the second feature can mean that the first feature is located directly above or diagonally above the second feature, or simply that the first feature is located on a higher horizontal plane than the second feature. The indication that the first feature is located "below" or "under" the second feature can mean that the first feature is located directly or diagonally below the second feature, or simply that the first feature is located on a lower horizontal plane than the second feature.

[0091] Unless otherwise stated, all parameters mentioned in this disclosure are tested at a temperature of 25 °C.

[0092] The battery cells mentioned in the embodiments of this disclosure are able to charge and discharge independently of each other.

[0093] The battery cells mentioned in the embodiments of this disclosure can be pouch battery cells or hard-shell battery cells.

[0094] The battery apparatus mentioned in the embodiments of this disclosure can comprise one or more battery cell assemblies that provide voltage and capacity. A battery cell assembly can comprise several battery cells, wherein the several battery cells are connected via a busbar in series, parallel, or in a mixed configuration.

[0095] In some embodiments, a battery cell assembly is typically formed by arranging several battery cells.

[0096] For example, a battery cell assembly can be a battery module, where the battery module consists of several battery cells arranged and secured to form an independent module. For example, a battery module can be formed by bundling several battery cells together with cable ties.

[0097] In some embodiments, the battery device may be a battery pack, wherein the battery pack comprises a housing and one or more battery cell assemblies, the battery cell assemblies being housed in the housing.

[0098] For example, the battery cell assembly can be a battery module, whereby the battery cell assembly can be housed in the casing by attaching the battery module to the casing.

[0099] For example, the battery cell assembly can also be housed in the casing by attaching several battery cells directly to the casing.

[0100] For example, the housing can comprise a first housing and a second housing. The first and second housings interlock, forming a closed space within the housing to accommodate the battery cell assembly. Here, "closed" refers to covering or sealing, which can be either sealed or unsealed. The first housing can be a top cover or a bottom plate.

[0101] For example, the housing can comprise a top cover, a frame, and a base plate. The top cover and the base plate are each connected to the frame, forming an enclosed space within the housing to accommodate the battery cell assembly.

[0102] In some embodiments, the housing can be part of the chassis structure. For example, part of the housing can be at least part of the vehicle floor, or part of the housing can be at least part of the vehicle's cross members and longitudinal members.

[0103] Fig. Figure 1 shows a schematic representation of a battery device 100, which is provided by an exemplary embodiment. Fig. Figure 2 shows an exploded view of a battery device 100, which is provided by an exemplary embodiment. Fig. Figure 3 shows an enlarged partial view of the in Fig. 2 shown battery device 100.

[0104] As in Fig. As shown in Figures 1 to 3, the battery device 100 comprises a housing 10 and several battery cells 22. The housing 10 comprises a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 interlock, forming a closed space within the housing 10 for receiving the battery cell assembly 22.

[0105] As in Fig. As shown in Figure 2, the first housing 11 is an upper cover, and the second housing 12 comprises a support plate 121 and a frame 122 that encloses the outer perimeter of the support plate 121, the support plate 121 and the frame 122 being rigidly connected to each other.

[0106] The battery cell 22 is a pouch battery cell. The multiple battery cells 22 are stacked in a first direction X and housed in the casing 10, the surface of each battery cell 22 comprising a first surface and a second surface, the first surface being larger than the second, the first surfaces of the multiple battery cells 22 being arranged opposite each other along the first direction X, while the carrier plate 121 is arranged opposite the second surfaces of the multiple battery cells 22 along a second direction Z.

[0107] Optionally, the nominal capacity of each battery cell is 22, at least 100 Ah.

[0108] As in Fig.As shown in Figure 1, at least one connecting beam 13 is provided in the housing 10, which extends in a third direction Y, wherein this connecting beam 13 is firmly connected to the support plate 121 and / or the frame 122, wherein at least one battery cell 22 is supported along the first direction X on the connecting beam 13.

[0109] The first direction X, the second direction Z and the third direction Y are all perpendicular to each other.

[0110] In some embodiments, the battery device 100 further comprises a thermal management component 30, wherein the thermal management component 30 is arranged between the carrier plate 121 and the battery cell 22 in order to regulate the temperature of the battery cell 22. The thermal management component 30 is arranged opposite the second surfaces of the multiple battery cells 22 along the second direction Z.

[0111] In some embodiments, the battery device 100 further comprises a receiving housing 23, wherein the receiving housing 23 contains at least one battery cell 22. The receiving housing 23 and the battery cells 22 contained therein together form the battery cell assembly 20.

[0112] In some embodiments, the battery device 100 further comprises a fastening adhesive 40, wherein the fastening adhesive 40 is arranged between the thermal management component 30 and the battery cell 22 in order to fasten the battery cell 22 to the thermal management component 30.

[0113] For example, the adhesive 40 can be applied directly to the housing of the battery cell 22.

[0114] For example, the adhesive 40 can be attached directly to the wall of the receiving housing 23.

[0115] The technical solutions described in the embodiments of this disclosure are applicable to a wide variety of electrical devices that use battery cells or battery devices. These include, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid vehicles, plug-in hybrid vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, and energy storage systems, etc. Battery cells and battery devices are used for storing or providing electrical energy.

[0116] Fig. Figure 4 is a schematic representation of an example electrical device. The electrical device is a pure electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, etc.

[0117] The battery cell provided in the embodiments of this disclosure can be a lithium-ion battery cell.

[0118] The discharge of a lithium-ion battery cell is the process by which lithium ions are extracted from the active material of the negative electrode and transferred by the electrolyte into the active material of the positive electrode. In the battery industry, the state of charge (SOC) is commonly used to indicate the remaining capacity of a battery cell after discharge. It is defined numerically as the percentage of the remaining capacity relative to the initial capacity of the battery cell and ranges from 0% to 100%. An SOC value of 0% means that the battery cell is completely discharged; an SOC value of 100% means that the battery cell is completely charged.

[0119] Lithium-ion battery cells are inevitably used in cold regions. There, the low temperature causes the polyolefin separator film to shrink, resulting in smaller pore sizes and increased resistance to lithium ions during discharge at low temperatures. Simultaneously, the low temperature increases the viscosity of the electrolyte and the resistance of the Faraday reaction at the electrode surface, leading to increased concentration polarization and interfacial Faraday polarization of the battery cell. Furthermore, the shrinkage of the electrode plates at low temperatures worsens the contact pressure at the interfaces of the electrode assembly, further increasing the interfacial resistance.

[0120] Therefore, at low temperatures, the battery cell exhibits slowed lithium-ion insertion and removal kinetics at the surface of the positive and negative electrodes, and the reaction resistance increases. The battery cells exhibit insufficient discharge performance in later discharge phases. For example, during discharge from a state of charge (SOC) of 10% to 0%, the remaining capacity of the battery cell may be difficult to discharge, indicating poor performance at low temperatures and low states of charge (SOC).

[0121] In light of this, the embodiments of the present disclosure provide a battery cell, a battery device, and an electrical device incorporating this battery cell. By matching the negative electrode and the separator film of the battery cell, it is enabled that the battery cell exhibits good performance at low temperatures and low states of charge (SOC), as well as good cycle performance at low temperatures.

[0122] The battery cell provided in the embodiments of this disclosure comprises a housing and an electrode assembly, wherein the electrode assembly is located inside the housing.

[0123] Fig. Figure 5 shows an exploded view of an electrode assembly provided by some embodiments of the present disclosure. Fig.Figure 6 shows an exploded view of an electrode assembly provided by some other embodiments of the present disclosure.

[0124] As in Fig. 5 and Fig.As shown in Figure 6, the electrode assembly comprises a positive electrode plate 24, a negative electrode plate 25, and a separator film 26, the separator film 26 being arranged between the positive electrode plate 24 and the negative electrode plate 25. The negative electrode plate 25 comprises a negative electrode current collector 250 and a negative electrode film layer located on at least one side of the negative electrode current collector 250. The negative electrode film layer comprises an active material of the negative electrode. The negative electrode film layer comprises a first negative electrode film layer 251, which is located away from the negative electrode current collector 250, and a second negative electrode film layer 252, which is located near the negative electrode current collector 250.The first negative electrode film layer 251 comprises a first active material of the negative electrode, and the second negative electrode film layer 252 comprises a second active material of the negative electrode. The first active material of the negative electrode contains a first silicon-based material and a first carbon-based material, the second active material of the negative electrode contains a second carbon-based material, and the mass fraction of the silicon element in the negative electrode film layer is 0.5% to 6%. The separator film 26 comprises a base film 260, a first porous coating 261 on the side of the base film 260 facing the negative electrode 25, and a second porous coating 262 on the side of the base film 260 facing the positive electrode 24. Both the first porous coating 261 and the second porous coating 262 contain filler particles.

[0125] Silicon-based material is an active material of the negative electrode that provides at least the silicon element. The silicon-based material can also provide other elements such as the carbon element, or, of course, only the silicon element. Carbon-based material is an active material of the negative electrode that provides at least the carbon element. In the present disclosure, the first negative electrode film layer located away from the negative electrode current collector comprises a first silicon-based material and a first carbon-based material. The silicon element in the negative electrode film layer is present at least in the form of the first silicon-based material in the negative electrode film layer, and the mass fraction of the silicon element in the negative electrode film layer is not less than 0.5%.

[0126] Compared to carbon-based materials, silicon-based materials typically exhibit lower electronic conductivity. Therefore, by incorporating the first silicon-based and the first carbon-based material into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a mass fraction of at least 0.5% of the silicon element in the negative electrode film layer, the internal ohmic resistance at the interface between the positive and negative electrode plates can be increased. Consequently, this configuration allows the first negative electrode film layer to rapidly heat the negative electrode plate and the battery cell during low-temperature discharge. The reaction kinetics of a battery cell are temperature-dependent.As the temperature of the negative electrode plate and the battery cell increases, the reaction kinetics of the battery cell improves at low temperatures.

[0127] Compared to carbon-based materials, silicon-based materials exhibit a greater volume expansion. Therefore, by incorporating the first silicon-based and the first carbon-based materials into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a mass fraction of at least 0.5% of the silicon element in the negative electrode film layer, the volume expansion of the negative electrode can be increased. This results in the negative and positive electrode plates being positioned closer together in a low-temperature environment. The reaction kinetics of a battery cell are related to the contact pressure of the internal interfaces within the electrode plates.The closer the negative and positive electrode plates are to each other, the smaller the gap between them, the lower the interfacial resistance of the battery cell, and the better the wettability of the electrode plates by the electrolyte. This leads to a higher electrochemical reaction rate of the electrode plates and thus improves the reaction kinetics of the battery cell at low temperatures.

[0128] Compared to carbon-based materials, silicon-based materials exhibit a higher lithium intercalation potential and are less prone to lithium deposition at the negative electrode at low temperatures. Therefore, by incorporating the first silicon-based and the first carbon-based materials into the first negative electrode film layer furthest from the negative electrode current collector, and by ensuring a silicon element mass fraction of at least 0.5% in the negative electrode film layer, the problem of lithium deposition at the negative electrode during low-temperature charging can be reduced.

[0129] At the same time, the mass fraction of the silicon element in the negative electrode film layer must not exceed 6%. If the mass fraction of the silicon element in the negative electrode film layer is too high, this leads to excessive volume expansion of the negative electrode, which impairs the wettability of the electrode assembly by the electrolyte, as well as the charging and discharging behavior of the battery cell and the performance of the battery cell at low temperatures and low states of charge (SOC).

[0130] At low temperatures, conventional polyolefin separator films shrink, reducing their pore size and increasing the through-resistance to lithium ions during low-temperature battery cell discharge. The present disclosure provides for applying a first porous coating and a second porous coating containing filler particles to both sides of the base film. Since the filler particles themselves possess a certain toughness, when arranged on both sides of the base film, they can reduce the shrinkage behavior of the base film at low temperatures, resulting in a larger pore size and higher porosity of the separator film at low temperatures.Consequently, the contact resistance for lithium ions during low-temperature battery cell discharge can be reduced, improving the battery cell's performance at low temperatures and low states of charge (SOC). Furthermore, the filler particles exhibit high mechanical strength. Their arrangement on both sides of the base film can increase the mechanical strength and puncture resistance of the separator film and also help reduce mechanical micro-short circuits.

[0131] The mass fraction of the silicon element in the negative electrode film layer of the present disclosure must be between 0.5% and 6% to allow the negative electrode to expand to a certain extent, thus enabling the negative and positive electrode plates to lie closer together in a low-temperature environment. However, the expansion of the negative electrode leads to compression of the separator film and the leakage of the electrolyte stored in its pores. Since the viscosity of the electrolyte is high at low temperatures and the wettability of the separator film by the electrolyte is generally insufficient, the volume expansion of the negative electrode can locally lead to dry areas in the separator film, which impairs the charging and discharging performance of the battery cell.Compared to the base film, the filler particles exhibit a higher electrolyte affinity, which improves the wettability of the separator film by the electrolyte and increases the lithium-ion conductivity of the separator film. Simultaneously, the first and second porous coatings can store electrolyte, enhancing the separator film's electrolyte retention capacity. This ensures the formation of an electrolyte-filled salt bridge between the positive and negative electrode plates, which in turn increases the lithium-ion transport kinetics during the battery cell's discharge process at low temperatures.

[0132] Therefore, this revelation, through the matching of the negative electrode and the separator film of the battery cell, enables the battery cell to exhibit good performance at low temperatures and low state of charge (SOC), as well as good cycle performance at low temperatures. [Separator film]

[0133] The separator film 26 comprises a base film 260, a first porous coating 261 on the side of the base film 260 facing the negative electrode 25, and a second porous coating 262 on the side of the base film 260 facing the positive electrode 24. Both the first porous coating 261 and the second porous coating 262 contain filler particles.

[0134] In some embodiments, the thickness of the first porous coating is 0.5 µm to 2 µm; for example, it may be 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 1.1 µm, 1.2 µm, 1.3 µm, 1.4 µm, 1.5 µm, 1.6 µm, 1.7 µm, 1.8 µm, 1.9 µm, 2 µm, or a range formed by any of the above values.

[0135] In some embodiments, the thickness of the second porous coating is 0.5 µm to 2 µm; for example, it can be 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 1.1 µm, 1.2 µm, 1.3 µm, 1.4 µm, 1.5 µm, 1.6 µm, 1.7 µm, 1.8 µm, 1.9 µm, 2 µm, or a range formed by any of the above values.

[0136] In some embodiments, the ratio of the thickness of the first porous coating to the thickness of the second porous coating is 0.9:1 to 1.1:1.

[0137] The similar thickness of the first and second porous coatings allows for similar pore sizes on both surfaces of the base film, further reducing the through-resistance for lithium ions during discharge of the battery cell at low temperatures.

[0138] Optionally, the thicknesses of the first porous coating and the second porous coating are the same.

[0139] The thickness of the first porous coating and the second porous coating each refer to the average thickness. During measurement, multiple points (e.g., more than 10) can be measured and the average value then calculated.

[0140] In some embodiments, the volumetric distribution particle diameter Dv50 of the filler particles is 0.2 µm to 0.8 µm, for example it can be 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm or a range formed by any of the above values.

[0141] In some embodiments, the specific surface area of ​​the filler particles is 10 m². 2 / g up to 1500 m 2 / g, for example, it can m 10 m 2 / g, 20 m 2 / g, 30 m 2 / g, 40 m 2 / g, 50 m 2 / g, 60 m 2 / g, 70 m 2 / g, 80 m 2 / g, 90 m 2 / g, 100 m 2 / g, 110 m 2 / g, 120 m 2 / g, 130 m 2 / g, 140 m 2 / g, 150 m 2 / g, 160 m 2 / g, 170 m 2 / g, 180 m 2 / g, 190 m 2 / g, 200 m 2 / g, 220 m 2 / g, 240 m 2 / g, 260 m 2 / g, 280 m 2 / g, 300 m 2 / g, 320 m 2 / g, 340 m 2 / g, 360 m 2 / g, 380 m 2 / g, 400 m 2 / g, 500 m 2 / g, 600 m 2 / g, 700 m 2 / g, 800 m 2 / g, 900 m 2 / g, 1000 m 2 / g, 1100 m 2 / g, 1200 m 2 / g, 1300 m 2 / g, 1400 m 2 / g, 1500 m 2 / g or a range formed by any of the values ​​mentioned above.

[0142] Optionally, the specific surface area of ​​the filler particles is 10 m². 2 / g up to 1000 m 2 / g, 10 m 2 / g up to 800 m 2 / g, 10 m 2 / g up to 600 m 2 / g, 10 m 2 / g bis 400 m 2 / g, 10 m 2 / g bis 300 m 2 / g, 10 m 2 / g bis 200 m 2 / g, 20 m 2 / g bis 1000 m 2 / g, 20 m 2 / g bis 800 m 2 / g, 20 m 2 / g bis 600 m 2 / g, 20 m 2 / g bis 400 m 2 / g, 20 bis m 2 / g bis 300 m 2 / g, 20 m 2 / g bis 200 m 2 / g, 40 m 2 / g bis 1000 m 2 / g, 40 m 2 / g bis 800 m 2 / g, 40 bis m 2 / g bis 600 m 2 / g, 40 m 2 / g bis 400 m 2 / g, 40 m 2 / g bis 300 m 2 / g, 40 m 2 / g bis 200 m 2 / g, 60 m 2 / g bis 1000 m 2 / g, 60 m 2 / g bis 800 m 2 / g, 60 m 2 / g bis 600 m 2 / g, 60 m 2 / g bis 400 m 2 / g, 60 m 2 / g bis 300 m 2 / g, 60 m 2 / g bis 200 m 2 / g, 80 m 2 / g bis 1000 m 2 / g, 80 m 2 / g up to 800 m 2 / g, 80 m 2 / g up to 600 m 2 / g, 80 m 2 / g up to 400 m 2 / g, 80 m 2 / g up to 300 m 2 / g, 80 m 2 / g up to 200 m 2 / g, 100 m 2 / g up to 1000 m 2 / g, 100 m 2 / g up to 800 m 2 / g, 100 m 2 / g up to 600 m 2 / g, 100 m 2 / g up to 400 m 2 / g, 100 m 2 / g up to 300 m 2 / g, 100 m 2 / g up to 200 m 2 / G.

[0143] In some embodiments, the filler particles have a porous structure.

[0144] Porous filler particles exhibit a higher electrolyte affinity, which improves the wettability of the separator film by the electrolyte and increases the lithium-ion conductivity of the separator film. Simultaneously, the porous structure of the filler particles allows them to store electrolyte, thus enhancing the separator film's electrolyte retention capacity. This ensures the formation of an electrolyte-filled salt bridge between the positive and negative electrode plates, which in turn improves the lithium-ion transport kinetics during low-temperature battery cell discharge and optimizes its low-temperature, low-state-of-charge (SOC) performance, as well as its low-temperature cycle performance.

[0145] In some embodiments, the filler particles comprise one or more of the following substances: inorganic particles, organic particles, and organic-inorganic composite particles.

[0146] In some embodiments, the inorganic particles may comprise one or more of the following substances: aluminum oxide, silicon dioxide, zirconium dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, silicon carbide, magnesium carbide, molecular sieve, zeolite and Prussian blue.

[0147] Optionally, the molecular sieve can contain one or more of the following types: A, X, Y, M and ZSM.

[0148] In some embodiments, organic particles may include polymer particles.

[0149] In some embodiments, organic-inorganic composite particles may comprise one or more of the following materials: covalent organic framework materials (COFs) and metal-organic framework materials (MOFs).

[0150] Optionally, the metal-organic framework material can include one or more of the following materials: ZIF materials (such as ZIF-8, ZIF-68, etc.), UiO materials, CPL materials, and MIL materials.

[0151] In some embodiments, the filler particles comprise inorganic particles, and the inorganic particles are aggregates of primary particles. The spaces between the primary particles that make up the aggregate form pores.

[0152] Optionally, the average particle size of the primary particles that make up the aggregate is less than 50 nm.

[0153] Optionally, the inorganic particles may include one or more of the following substances: aluminum oxide, silicon dioxide, zirconium dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, silicon carbide and magnesium carbide.

[0154] In some embodiments, the first porous coating and the second porous coating further comprise a binder. The binder may, but is not limited to, comprise one or more of the following substances: polyacrylate binder, nitrile rubber binder, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0155] In some embodiments, the first porous coating and the second porous coating may further comprise a dispersant. The dispersant may include, but is not limited to, sodium carboxymethylcellulose.

[0156] In some embodiments, the separator film may further comprise an adhesive layer. The adhesive layer comprises polymer binder particles and is arranged on at least portions of the surface of the first porous coating and / or the second porous coating facing away from the base film. As in Fig. As shown in Figure 3, the separator film further comprises an adhesive layer 303. The adhesive layer 303 comprises polymer binder particles, wherein the adhesive layer 303 is arranged on at least parts of the surface of the first porous coating 261 and the second porous coating 262 that face away from the base film 260.

[0157] The filler particles in the first and second porous coatings primarily serve to reduce shrinkage of the base film at low temperatures. They themselves have no (or essentially no) binding properties.

[0158] Polymer binder particles have a binding property that enables a firm connection of the electrode plates, reduces the gap between the electrode plates, improves the wettability of the electrode plates by the electrolyte, and improves the cycle performance of the battery cells at low temperatures.

[0159] In some embodiments, the polymer binder particles comprise one or more of the following substances: vinylidene fluoride polymer particles and acrylate copolymer particles.

[0160] Vinylidene fluoride polymer particles can comprise polyvinylidene fluoride (PVDF) particles and / or copolymer particles of vinylidene fluoride monomer and comonomers. The comonomers can include at least one of the following monomers: olefin monomers, fluorinated olefin monomers, chlorinated olefin monomers, acrylate monomers, acrylic monomers, and fluoroether monomers. Optionally, the comonomers can include at least one of the following: trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ethers (e.g., perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether), perfluoro(1,3-m-dioxacyclopentene, and perfluoro(2,2-dimethyl-1,3-m-dioxacyclopentene).

[0161] In some embodiments, the volumetric distribution particle diameter Dv50 of the polymer binder particles is 2 µm to 8 µm, for example it can be 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm or a range formed by any of the above values.

[0162] The present disclosure is not subject to any particular restriction regarding the type of base film. Any generally known porous base film with good chemical and mechanical stability may be used. In some embodiments, the separator film material may be one or more of the following materials: glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The base film may be a single-layer film or a multi-layer composite film, without any particular restriction. If the base film is a multi-layer composite film, the materials of the individual layers may be the same or different, without any particular restriction.

[0163] In some embodiments, the thickness of the base film is 5 µm to 10 µm; for example, it can be 5 µm, 5.5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, or a range formed by any of the above values.

[0164] In some embodiments, the thickness of the separator film is 7 µm to 14 µm; for example, it can be 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, or a range formed by any of the above values.

[0165] The thickness of the base film and the separator film each refer to the average thickness. During measurement, multiple points (e.g., more than 10) can be measured and the average value then calculated.

[0166] In some embodiments, the porosity of the separator film at 25 °C is 40% to 60% and the porosity of the separator film at -25 °C is 10% to 35%.

[0167] For example, the porosity of the separator film at 25 °C can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, or a range formed by any of the above values. The porosity of the separator film at -25 °C can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or a range formed by any of the above values.

[0168] The porosity of the separator film can be tested according to GB / T 36363-2018. [Negative electrode]

[0169] The negative electrode plate 25 comprises a negative electrode current collector 250 and a negative electrode film layer located on at least one side of the negative electrode current collector 250. The negative electrode film layer comprises an active material of the negative electrode. The negative electrode film layer comprises a first negative electrode film layer 251, located away from the negative electrode current collector 250, and a second negative electrode film layer 252, located near the negative electrode current collector 250. The first negative electrode film layer 251 comprises a first active material of the negative electrode, and the second negative electrode film layer 252 comprises a second active material of the negative electrode.The first active material of the negative electrode contains a silicon-based material and a carbon-based material, and the second active material of the negative electrode contains a carbon-based material, and the mass fraction of the Si element in the negative electrode film layer is 0.5% to 6%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, or a range formed by any of the above values.

[0170] Optionally, the mass fraction of the Si element in the negative electrode film layer is 1.5% to 5%.

[0171] The mass fraction of the silicon element in the negative electrode film layer can be measured using an inductively coupled plasma emission spectrometer (ICP). The test standard can be found in JY / T 015 1996. The mass fraction of the silicon element in the negative electrode film layer refers to the mass fraction of the silicon element in the entire negative electrode film layer.

[0172] The active material of the negative electrode comprises a first active material of the negative electrode and a second active material of the negative electrode.

[0173] In some embodiments, the volumetric particle size distribution diameter Dv10 of the active material of the negative electrode is 4 µm to 8 µm, for example it can be 4 µm, 4.5 µm, 5 µm, 5.5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm or a range formed by any of the above values.

[0174] In some embodiments, the volumetric particle size distribution diameter Dv50 of the active material of the negative electrode is 10 µm to 25 µm, for example it can be 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, 25 µm or a range formed by any of the above values.

[0175] In some embodiments, the volumetric particle size distribution diameter Dv90 of the active material of the negative electrode is 25 µm to 40 µm, for example it can be 25 µm, 26 µm, 27 µm, 28 µm, 29 µm, 30 µm, 31 µm, 32 µm, 33 µm, 34 µm, 35 µm, 36 µm, 37 µm, 38 µm, 39 µm, 40 µm or a range formed by any of the above values.

[0176] The active material of the negative electrode has a suitable particle size, resulting in a rapid solid-state diffusion rate of lithium ions and lower concentration polarization. This improves the reaction kinetics of the battery cell at low temperatures.

[0177] In some embodiments, the specific surface area of ​​the active material of the negative electrode is 3 m². 2 / g up to 7 m 2 / g, for example, it can 3 m 2 / g, 3.5 m 2 / g, 4 m 2 / g, 4.5 m 2 / g, 5 m 2 / g, 5.5 m 2 / g, 6 m 2 / g, 6.5 m 2 / g, 7 m 2 / g or a range formed by any of the values ​​mentioned above.

[0178] The first active material of the negative electrode comprises a first silicon-based material and a first carbon-based material, and the second active material of the negative electrode comprises a second carbon-based material.

[0179] In some embodiments, the first carbon-based material comprises one or more of the following substances: synthetic graphite, natural graphite.

[0180] Optionally, the first carbon-based material contains artificial graphite, and the surface of the artificial graphite has a carbon coating, the carbon coating being made of soft carbon and / or hard carbon.

[0181] Synthetic graphite possesses a high specific capacity. Coating it with a carbon layer allows for the modification of surface defects and the improvement of the battery cells' energy density. The carbon layer consists of soft and / or hard carbon, forming three-dimensional ion channels. This carbon layer enhances the kinetics of the synthetic graphite and, consequently, the kinetics of the battery cells. Furthermore, the carbon layer reduces the volume change of the synthetic graphite and minimizes side reactions between the graphite and the electrolyte, resulting in the formation of a higher-quality SEI film. This reduces the loss of active lithium and electrolyte through the repair of SEI film damage and ultimately improves the cycle performance of the battery cells.

[0182] In some embodiments, the degree of graphitization of the first carbon-based material is 90% to 96%, for example it may be 90%, 91%, 92%, 94%, 95%, 96% or a range formed by any of the above values.

[0183] If the graphitization degree of the first carbon-based material is within the aforementioned range, it exhibits both a high specific capacity and good ion transport performance, which is advantageous for the battery cell in order to achieve both high energy density and good reaction kinetics at low temperatures.

[0184] Optionally, the graphitization level of the first carbon-based material is 92.5% to 95.5%.

[0185] In some embodiments, the OI value of the carbon-based first material powder is 0.8 to 1.7, for example it may be 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or a range formed by any of the above values.

[0186] The first carbon-based material exhibits a low oxide inertness (OI) of the powder and lithium ion intercalation sites in all directions across the particles. This promotes the rapid uptake of lithium ions from the positive electrode, thus improving the kinetics of the battery cell. Simultaneously, this first carbon-based material is characterized by high isotropy, which better distributes the volume expansion caused by lithium ion intercalation. This also leads to the formation of a higher-quality SEI film, reduces the loss of active lithium and electrolyte through the repair of SEI film damage, and thus improves the cycle performance of the battery cell.

[0187] In some embodiments, the second carbon-based material comprises one or more of the following substances: synthetic graphite, natural graphite.

[0188] Optionally, the second carbon-based material includes natural graphite.

[0189] Natural graphite typically exhibits a certain degree of porosity, which makes it more ductile and pressure-resistant. Therefore, the use of natural graphite in the second negative electrode film layer contributes to improving the compaction density of this negative electrode film layer and the volumetric energy density of the battery cell.

[0190] In some embodiments, the degree of graphitization of the second carbon-based material is 90% to 96%, for example it may be 90%, 91%, 92%, 94%, 95%, 96% or a range formed by any of the above values.

[0191] If the graphitization degree of the second carbon-based material is within the aforementioned range, it exhibits both a high specific capacity and good ion transport performance, which is advantageous for the battery cell in order to achieve both high energy density and good reaction kinetics at low temperatures.

[0192] Optionally, the graphitization level of the second carbon-based material is 92.5% to 95.5%.

[0193] In some embodiments, the OI value of the second carbon-based material powder is 0.8 to 1.7; for example, it may be 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or a range formed by any of the above values.

[0194] The second carbon-based material exhibits a low oxide inertness (OI) of the powder and lithium ion intercalation sites in all directions across the particles. This promotes the rapid uptake of lithium ions from the positive electrode, thus improving the kinetics of the battery cell. Simultaneously, this second carbon-based material is characterized by high isotropy, which better distributes the volume expansion caused by lithium ion intercalation. This also leads to the formation of a higher-quality SEI film, reduces the loss of active lithium and electrolyte through SEI film repair, and thus improves the cycle performance of the battery cell.

[0195] In some embodiments, the first silicon-based material comprises one or more of the following substances: elemental silicon, silicon-carbon material, silicon oxides, silicon nitrides, and silicon alloys.

[0196] Optionally, the first silicon-based material includes silicon oxides.

[0197] Silicon oxides can contain alkali metal elements and / or alkaline earth metal elements, or they can contain neither. Optionally, the silicon oxide can contain alkali metal elements and / or alkaline earth metal elements; for example, the silicon oxide can be used as a matrix, with alkali metal elements and / or alkaline earth metal elements being embedded by chemical or physical processes.

[0198] Silicon-carbon material can contain alkali metal elements and / or alkaline earth metal elements, or it can contain neither. Optionally, the silicon-carbon material can contain alkali metal elements and / or alkaline earth metal elements; for example, the silicon-carbon material can be used as a matrix, with alkali metal elements and / or alkaline earth metal elements embedded by chemical or physical processes.

[0199] Optionally, the alkali metal element can include Li and the alkaline earth metal element can contain Mg.

[0200] Optionally, the silicon-carbon material can contain porous carbon and silicon located in the pores of the porous carbon.

[0201] In some embodiments, the second active material of the negative electrode can further comprise a second silicon-based material. Optionally, the second silicon-based material comprises one or more of the following: elemental silicon, silicon-carbon material, silicon oxides, and silicon nitrides.

[0202] Optionally, the mass fraction of the Si element in the first negative electrode film layer is greater than the mass fraction of the Si element in the second negative electrode film layer.

[0203] Compared to carbon-based materials, silicon-based materials exhibit a higher lithium intercalation potential and are less prone to lithium deposition at low temperatures. The first negative electrode film layer is located at the surface, the second at the base. A high mass fraction of silicon in the surface region reduces lithium deposition at low temperatures on the negative electrode. A low mass fraction of silicon in the base region minimizes damage to the conductive network of the negative electrode film layer caused by the volume expansion of the silicon-based material, thus improving the charging and discharging performance of the battery cell.

[0204] In some embodiments, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 5:95 to 50:50; for example, it can be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, or a range formed by any of the above values.

[0205] The first negative electrode film layer exhibits high volume expansion and high resistance. By maintaining the thickness ratio of the first to the second negative electrode film layer within the aforementioned range, the operating temperature of the battery cell can be increased, the gap between the electrode plates reduced, and good electrolyte wettability and electrolyte retention of the negative electrode plates and the separator film achieved. This results in good performance at low temperatures and low states of charge (SOC), as well as good cycle performance at low temperatures.

[0206] Optionally, the thickness ratio of the first negative electrode film layer to the second negative electrode film layer is 15:85 to 50:50, 20:80 to 50:50, 25:75 to 50:50, 30:70 to 50:50.

[0207] In some embodiments, the first negative electrode film layer and the second negative electrode film layer may further comprise a conductive material for the negative electrode. For example, the conductive material of the negative electrode may, but is not limited to, comprise one or more of the following materials: superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen carbon black, carbon nanoparticles, carbon nanotubes, graphene, or carbon nanofibers.

[0208] In some embodiments, the first negative electrode film layer and the second negative electrode film layer may further comprise a negative electrode binder. For example, but not limited to, the negative electrode binder may comprise one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0209] In some embodiments, the first negative electrode film layer and the second negative electrode film layer may further comprise additional excipients. For example, these excipients may include thickening agents such as sodium carboxymethylcellulose (CMC), PTC thermistor materials, etc.

[0210] The negative electrode film layer comprises a first negative electrode film layer located away from the negative electrode current collector and a second negative electrode film layer located near the negative electrode current collector.

[0211] By sectioning the negative electrode plate along the direction perpendicular to the surface of the negative electrode film layer and using a scanning electron microscope, a cross-sectional SEM image of the negative electrode film layer in the thickness direction can be acquired. Alternatively, by combining the scanning electron microscope with an energy-dispersive X-ray spectrometer (EDS), a cross-sectional SEM-EDS image of the negative electrode film layer in the thickness direction can be acquired. The first and second negative electrode film layers are easily distinguishable in these images.

[0212] In some embodiments, the specific surface area of ​​the negative electrode film layer is 0.5 m². 2 / g up to 2 m 2 / g, for example, it can 0.5 m 2 / g, 0.6 m 2 / g, 0.8 m 2 / g, 1 m 2 / g, 1.2 m 2 / g, 1.4 m 2 / g, 1.6 m 2 / g, 1.8 m 2 / g, 2 m 2 / g or a range formed by any of the values ​​mentioned above.

[0213] In some embodiments, the porosity of the negative electrode film layer is 20% to 30%, for example it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% or a range formed by any of the above values.

[0214] In some embodiments, the OI value of the negative electrode film layer is 5 to 10; for example, it may be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or a range formed by any of the above values.

[0215] If the OI value of the negative electrode film layer is within the range mentioned above, this is advantageous for improving the lithium ion storage performance of the negative electrode film layer, which in turn promotes the improvement of the reaction kinetics of the battery cell at low temperatures.

[0216] In some embodiments, the compaction density of the negative electrode film layer is 1.4 g / cm³. 3 up to 1.7 g / cm³ 3 , for example, it can be 1.4 g / cm² 1 , 1.45 g / cm³ 1 , 1.5 g / cm³ 1 , 1.55 g / cm³ 1 , 1.6 g / cm³ 1 , 1.65 g / cm³ 1 , 1.7 g / cm³ 1or be a range formed by any of the values ​​mentioned above.

[0217] The higher the density of the negative electrode film layer, the higher the energy density of the battery cell. However, the curvature of the negative electrode film layer increases, leading to longer transport paths for lithium ions in the negative electrode, higher internal resistance, and poorer kinetics of the battery cell. By maintaining the density of the negative electrode film layer within the aforementioned range, the battery cell can exhibit both high energy density and good performance at low temperatures and low states of charge (SOC).

[0218] Optionally, the compaction density of the negative electrode film layer is 1.45 g / cm³. 3 up to 1.65 g / cm³ 3 .

[0219] In some embodiments, the thickness of the negative electrode film layer is 90 µm to 150 µm; for example, it can be 90 µm, 95 µm, 100 µm, 105 µm, 110 µm, 115 µm, 120 µm, 125 µm, 130 µm, 135 µm, 140 µm, 145 µm, 150 µm, or a range formed by any of the above values.

[0220] The thicker the negative electrode film layer, the higher the energy density of the battery cell. However, this also increases the transport path of the lithium ions in the negative electrode, raises the internal resistance of the battery cell, and worsens the battery cell's kinetics. By keeping the thickness of the negative electrode film layer within the aforementioned range, the battery cell can exhibit both high energy density and good performance at low temperatures and low states of charge (SOC).

[0221] The negative electrode film layer can be produced by applying a second paste to the negative electrode current collector, then applying a first paste over the second paste, and subsequently drying and cold-rolling. After the first paste dries, a first negative electrode film layer forms, and after the second paste dries, a second negative electrode film layer forms. The first paste is produced by dispersing and thoroughly mixing the first negative electrode active material, the negative electrode conductivity, the negative electrode binder, and other optional excipients in a solvent. N-methylpyrrolidone (NMP) or deionized water can be used as the solvent, but these are not the only options.The second paste is prepared by dispersing and thoroughly mixing the second active material of the negative electrode, the conductive material of the negative electrode, the binder of the negative electrode, and any other optional excipients in a solvent. N-methylpyrrolidone (NMP) or deionized water can be used as the solvent, but these are not the only options. The first and second pastes can be applied simultaneously or separately.

[0222] The negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is arranged on one or both of these opposing surfaces of the negative electrode current collector.

[0223] The parameters of the negative electrode film layer in this disclosure all refer to the negative electrode film layer on a single side of the negative electrode current collector.

[0224] In some embodiments, the negative current collector can be a metal foil or a composite current collector. A copper foil can be used as an example of a metal foil. The composite current collector can comprise a polymer substrate layer and a metal material layer formed on at least one surface of the polymer substrate layer. For example, the metal material can include, but is not limited to, one or more of the following: copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer substrate layer can include, but is not limited to, one or more of the following: polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene. [Positive electrode]

[0225] In some embodiments, the positive electrode plate 24 comprises a positive electrode current collector 240 and a positive electrode film layer 241 located on at least one side of the positive electrode current collector 240. The positive electrode film layer 241 comprises an active material of the positive electrode. The active material of the positive electrode comprises a lithium transition metal oxide. This lithium transition metal oxide contains nickel, the molar fraction of which among the transition metal elements in the lithium transition metal oxide is more than 80%.

[0226] The active material of the positive electrode in this disclosure comprises a lithium transition metal oxide with a high nickel content. The molar fraction of nickel in the transition metal elements of the lithium transition metal oxide is over 80%. The high nickel content of the lithium transition metal oxide results in a high theoretical specific capacity, enabling the battery cell to exhibit a high energy density.

[0227] Optionally, the molar fraction of the Ni element in the transition metal elements of the lithium transition metal oxide is above 85%, above 87% or above 90%.

[0228] In some embodiments, the lithium transition metal oxide comprises single-crystal lithium transition metal oxide, wherein the total area of ​​the single-crystal lithium transition metal oxide is 60% to 100% of the total area of ​​the active material of the positive electrode, for example, it may be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 99%, 100%, or a range formed by any of the above values.

[0229] In some embodiments, the lithium transition metal oxide comprises single-crystal lithium transition metal oxide, wherein the total area of ​​the single-crystal lithium transition metal oxide is 100% of the total area of ​​the active material of the positive electrode.

[0230] In some embodiments, the lithium transition metal oxide comprises monocrystalline lithium transition metal oxide and polycrystalline lithium transition metal oxide, wherein the total area of ​​the monocrystalline lithium transition metal oxide is 60% to 99% of the total area of ​​the active material of the positive electrode, and the total area of ​​the polycrystalline lithium transition metal oxide is 1% to 40% of the total area of ​​the active material of the positive electrode. For example, the total area of ​​the monocrystalline lithium transition metal oxide may be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, or 99% of the total area of ​​the active material of the positive electrode, or a range formed by any of the above values.For example, the total area of ​​the polycrystalline lithium transition metal oxide can be 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40% of the total area of ​​the active material of the positive electrode, or an area formed by any of the above values.

[0231] Optionally, the total area of ​​the single-crystal lithium transition metal oxide is 80% to 99% of the total area of ​​the active material of the positive electrode, and the total area of ​​the polycrystalline lithium transition metal oxide is 1% to 20% of the total area of ​​the active material of the positive electrode.

[0232] Optionally, the total area of ​​the single-crystal lithium transition metal oxide is 90% to 99% of the total area of ​​the active material of the positive electrode, and the total area of ​​the polycrystalline lithium transition metal oxide is 1% to 10% of the total area of ​​the active material of the positive electrode.

[0233] The terms "single-crystal lithium transition metal oxide" and "polycrystalline lithium transition metal oxide" have the generally accepted meanings in this field. "Single-crystal lithium transition metal oxide" also includes lithium transition metal oxides with quasi-single-crystal (also referred to as single-crystal-like) morphology. Quasi-single-crystal (single-crystal-like) has the generally accepted meaning in this field and usually refers to particles formed by the aggregation of a small number of particles, for example, fewer than 10 primary particles. Typically, the primary particles of lithium transition metal oxides that constitute quasi-single-crystal (or single-crystal-like) morphologies have a particle size of 500 nm or more.Polycrystalline lithium transition metal oxides are lithium transition metal oxides with a secondary particle morphology resulting from the aggregation of a large number of nanometer-sized primary particles. Single-crystal lithium transition metal oxides and polycrystalline lithium transition metal oxides can be distinguished using a scanning electron microscope.

[0234] The mean particle size of single-crystal and polycrystalline lithium transition metal oxides can be determined as follows: A scanning electron microscope (SEM) image of the positive electrode plate is acquired using a scanning electron microscope according to JY / T 010-1996. A test sample (e.g., 50 mm × 100 mm (length × width)) is randomly selected. Within this sample, several test areas (e.g., 5 areas) are randomly selected. At a specific magnification (e.g., 500x or higher), the number and particle size of the single-crystal and polycrystalline lithium transition metal oxides in each test area are determined. The arithmetic mean of the particle sizes of all single-crystal lithium transition metal oxides in each test area is used as the mean particle size of the single-crystal lithium transition metal oxides.The arithmetic mean of the particle sizes of all polycrystalline lithium transition metal oxides in each test area is used as the mean particle size of the polycrystalline lithium transition metal oxides. To ensure the accuracy of the test results, several test samples (e.g., 10) can be taken for the above test, and the mean of each sample can be used as the final test result. A ZEISS Sigma 300, for example, can be used as the testing instrument. It should be noted that for irregularly shaped particles, the distance between the two most distant points on the particle is used as the particle size.

[0235] The area ratio of single-crystal to polycrystalline lithium transition metal oxides in the active material of the positive electrode can be determined as follows: A scanning electron microscope (SEM) image of the positive electrode plate is acquired using a scanning electron microscope (SEM) according to JY / T 0 10-1996. A test sample (e.g., 50 mm × 100 mm (length × width)) is randomly selected. Within this sample, several test areas (e.g., 5 areas) are randomly selected. At a specific magnification (e.g., 500x or higher), the sum of the areas of all single-crystal lithium transition metal oxides, the sum of the areas of all polycrystalline lithium transition metal oxides, and the sum of the areas of all active materials of the positive electrode are calculated in each area. This yields the area ratio of single-crystal to polycrystalline lithium transition metal oxides.The mean of the test results from several test areas is then used as the area ratio of single-crystal lithium transition metal oxides to polycrystalline lithium transition metal oxides in the active material of the positive electrode. To ensure the accuracy of the test results, several test samples (e.g., 10) can be taken for the above-mentioned test, and the mean of each test sample can be used as the final test result. A ZEISS Sigma 300, for example, can be used as the testing instrument.

[0236] Single-crystal lithium transition metal oxides exhibit few or no grain boundaries, which reduces side reactions with the electrolyte. This can reduce the irreversible loss of active lithium and electrolyte, and consequently improve the cycle performance of the battery cell.

[0237] Polycrystalline lithium transition metal oxides exhibit higher electrochemical activity and higher specific capacity, which contributes to improving the kinetics and energy density of battery cells.

[0238] The average particle size of polycrystalline lithium transition metal oxides is larger than that of monocrystalline lithium transition metal oxides. Adding small amounts of polycrystalline lithium transition metal oxides to the active material of the positive electrode allows for a higher density of the positive electrode film layer, which in turn improves the energy density of the battery cell.

[0239] In some embodiments, the lithium transition metal oxide contains Ni and Co elements, with the Co content in the surface region of the lithium transition metal oxide being higher than the Co content in the core region of the lithium transition metal oxide.

[0240] The lithium transition metal oxide exhibits a high cobalt content in the surface region and a low cobalt content in the core region. This results in high surface stability of the lithium transition metal oxide, reducing side reactions with the electrolyte and the dissolution of transition metal ions. This improves the cycle performance of the battery cell. Furthermore, it increases the thermal stability of the lithium transition metal oxide and reduces the risk of thermal runaway in the battery cell.

[0241] In some embodiments, the lithium transition metal oxide contains Ni and Mn elements, wherein the Mn content in the surface region of the lithium transition metal oxide is lower than the Mn content in the core region of the lithium transition metal oxide.

[0242] The lithium transition metal oxide exhibits a low manganese content in the surface region and a high manganese content in the core region. This results in high surface stability of the lithium transition metal oxide, thereby reducing side reactions with the electrolyte and the dissolution of transition metal ions. This improves the cycle performance of the battery cell. Furthermore, it increases the thermal stability of the lithium transition metal oxide and reduces the risk of thermal runaway in the battery cell.

[0243] In some embodiments, the lithium transition metal oxide contains the elements Ni, Co and Mn, wherein the Co content in the surface region of the lithium transition metal oxide is higher than the Co content in the core region of the lithium transition metal oxide, while the Mn content in the surface region of the lithium transition metal oxide is lower than the Mn content in the core region of the lithium transition metal oxide.

[0244] The surface region of the lithium transition metal oxide is a region extending radially 100 nm inwards from the outermost surface of the particle, and the core region of the lithium transition metal oxide is a region extending radially 300 nm outwards from the center of the particle. The center of the particle is the midpoint of the longest straight line between any two points on the circumference of the particle.

[0245] The concentrations of individual elements in the surface and core regions of lithium transition metal oxide can be determined as follows: A particle cross-section sample is prepared using an ion beam cutter. A suitable image area is then selected using a scanning electron microscope, and the particle cross-section is scanned with an energy-dispersive X-ray spectrometer (EDS) in a 5k image area. The concentration of each element is measured at at least ten locations in the surface region of the particle cross-section, and the mean value serves as the result for the respective element concentration in the surface region of the lithium transition metal oxide. Similarly, the concentration of each element is measured at at least ten locations in the core region of the particle cross-section, and the mean value also serves as the result for the respective element concentration in the core region of the lithium transition metal oxide.

[0246] In some embodiments, the lithium transition metal oxide comprises Ni and dopant elements, wherein the dopant elements comprise cation and / or anion dopant elements, wherein the cation dopant elements comprise one or more of the elements Al, Y, Zr, Zn, Cr, Mg, V, Ti and B and the anion dopant elements comprise one or more of the elements N, F, S and Cl.

[0247] The cation doping element can be lithium and / or transition metal doping, and the anion doping element can be oxygen doping.

[0248] The doping elements can increase the structural stability of lithium transition metal oxides, reduce the volume change of lithium transition metal oxides during charging and discharging, decrease the dissolution of transition metal ions, and improve the chemical stability and cycle performance of battery cells; they can also increase the thermal stability of lithium transition metal oxides and reduce the risk of thermal runaway of battery cells.

[0249] In some embodiments, the lithium transition metal oxide has the composition Li a Ni b Co c Mn d M e O f A g where the following conditions apply: 0.8 ≤ a ≤ 1.2, 0.8 ≤ b < 1, 0 < c < 0.2, 0 < d < 0.2, 0 < e < 0.2, 1 ≤ f ≤ 2, 0 ≤ g ≤ 1. M comprises one or more of the following elements: Al, Y, Zr, Zn, Cr, Mg, V, Ti and B. A comprises one or more of the following elements: N, F, S and Cl.

[0250] During the charging and discharging process of the battery cell, lithium is stored, released, and consumed. The molar content of lithium varies in different discharge states. In the enumeration of the active materials for positive electrodes in this disclosure, the molar Li content refers to the initial state of the material, i.e., the state before the Li supply. When the active material for positive electrodes is used in the battery cells, the molar Li content changes after the charge-discharge cycles. In the enumeration of the active materials for positive electrodes in this disclosure, the molar oxygen content represents only a theoretical value. The release of oxygen from the crystal lattice leads to a change in the molar oxygen content, so the actual molar oxygen content also fluctuates.

[0251] In some embodiments, the volumetric particle size distribution diameter Dv10 of the active material of the positive electrode is 0.5 µm to 2.5 µm, for example it can be 0.5 µm, 0.6 µm, 0.8 µm, 1 µm, 1.2 µm, 1.4 µm, 1.6 µm, 1.8 µm, 2 µm, 2.2 µm, 2.5 µm or a range formed by any of the above values.

[0252] In some embodiments, the volumetric particle size distribution diameter Dv50 of the active material of the positive electrode is 2 µm to 6 µm, for example it can be 2 µm, 2.2 µm, 2.4 µm, 2.6 µm, 2.8 µm, 3 µm, 3.2 µm, 3.4 µm, 3.6 µm, 3.8 µm, 4 µm, 4.2 µm, 4.4 µm, 4.6 µm, 4.8 µm, 5 µm, 5.2 µm, 5.4 µm, 5.6 µm, 5.8 µm, 6 µm or a range formed by any of the above values.

[0253] In some embodiments, the volumetric particle size distribution diameter Dv90 of the active material of the positive electrode is 5 µm to 8 µm, for example it can be 5 µm, 5.2 µm, 5.4 µm, 5.6 µm, 5.8 µm, 6 µm, 6.2 µm, 6.4 µm, 6.6 µm, 6.8 µm, 7 µm, 7.2 µm, 7.4 µm, 7.6 µm, 7.8 µm, 8 µm or a range formed by any of the above values.

[0254] The active material of the positive electrode has a suitable particle size, resulting in a rapid solid-state diffusion rate of lithium ions and lower concentration polarization. This improves the reaction kinetics of the battery cell at low temperatures.

[0255] In some embodiments, the specific surface area of ​​the positive electrode film layer is 0.7 m². 2 / g up to 2 m 2 / g, for example, it can 0.7 m 2 / g, 0.8 m 2 / g, 1 m 2 / g, 1.2 m 2 / g, 1.4 m2 / g, 1.6 m 2 / g, 1.8 m 2 / g, 2 m 2 / g or a range formed by any of the values ​​mentioned above.

[0256] In some embodiments, the compaction density of the positive electrode film layer is 3.4 g / cm³. 3 up to 3.7 g / cm³ 3 , for example, it can be 3.4 g / cm² 3 , 3.45 g / cm³ 3 , 3.5 g / cm³ 3 , 3.55 g / cm³ 3 , 3.6 g / cm³ 3 , 3.65 g / cm³ 3 , 3.7 g / cm³ 3 or be a range formed by any of the values ​​mentioned above.

[0257] In some embodiments, the positive electrode film layer contains a positive electrode conductor. For example, the positive electrode conductor may, but is not limited to, comprise one or more of the following materials: superconducting carbon, conductive graphite, acetylene carbon black, carbon black, Ketjen carbon black, carbon nanoparticles, carbon nanotubes, graphene, or carbon nanofibers.

[0258] In some embodiments, the mass fraction of the conductive medium of the positive electrode in the positive electrode film layer is 0.1% to 1.5%, for example it may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5% or a range formed by any of the above values.

[0259] In some embodiments, the conductive material of the positive electrode comprises carbon nanotubes, and at least a portion of the carbon nanotubes is located on the surface of the active material of the positive electrode.

[0260] Carbon nanotubes include one or more of the following types: single-walled carbon nanotubes, few-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0261] Single-walled carbon nanotubes are formed by rolling up a single graphene layer, few-walled carbon nanotubes are formed by concentrically rolling up two to three graphene layers into a tubular structure, and multi-walled carbon nanotubes are formed by concentrically rolling up four or more graphene layers into a tubular structure.

[0262] Carbon nanotubes exhibit good electrical conductivity. This allows for a reduction in the mass fraction of the conductive material in the positive electrode film layer, an increase in the mass fraction of the active material in the positive electrode, and an improvement in the energy density of the battery cell. Furthermore, the use of carbon nanotubes can reduce the resistance of the positive electrode and the internal resistance of the battery cell, and improve the battery cell's performance at low temperatures and low states of charge (SOC).

[0263] By arranging the material so that at least some of the carbon nanotubes are located on the surface of the positive electrode's active material, the crystal structure of the active material can be stabilized and its particle strength increased. This reduces the volume change of the active material during charging and discharging. Consequently, this contributes to the formation of a stable SEI layer on the surface of the active material, reduces side reactions between the active material and the electrolyte, and minimizes the leaching of transition metal ions. This, in turn, improves the first Coulomb efficiency and the capacity retention rate of the battery cell.Placing at least some of the carbon nanotubes on the surface of the active material of the positive electrode promotes the formation of a uniform conductive network within the positive electrode. This improves electron transport in the positive electrode, reduces the electrical resistance to electron transport, and lowers the resistance and polarization of the positive electrode. Consequently, the performance of the battery cell is increased at low temperatures and low states of charge (SOC).

[0264] Optionally, the aspect ratio of the carbon nanotubes is 500 to 100000.

[0265] In some embodiments, the positive electrode film layer contains a positive electrode binder. For example, the positive electrode binder may, but is not limited to, comprise one or more of the following substances: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene propylene terpolymer, PVDF-hexafluoropropylene tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0266] The positive electrode film layer is typically produced by applying a positive electrode paste to the positive electrode current collector, followed by drying and cold rolling. The positive electrode paste is typically prepared by dispersing and thoroughly mixing the positive electrode active material, the positive electrode conductor, the positive electrode binder, and other components in a solvent. N-methylpyrrolidone (NMP) can be used as the solvent, but is not limited to this.

[0267] The positive electrode current collector has two opposite surfaces in its thickness direction, and the positive electrode film layer is arranged on one or both of these opposite surfaces of the positive electrode current collector.

[0268] The parameters of the positive electrode film layer in this disclosure all refer to the positive electrode film layer on a single side of the positive electrode current collector.

[0269] In some embodiments, the positive current collector can be a metal foil or a composite current collector. An aluminum foil can be used as an example of a metal foil. The composite current collector can comprise a polymer substrate layer and a metal material layer formed on at least one surface of the polymer substrate layer. For example, the metal material can include, but is not limited to, one or more of the following: aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer substrate layer can include, but is not limited to, one or more of the following: polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0270] Dv10, Dv50, and Dv90 denote the particle size corresponding to a cumulative volume distribution of 10%, 50%, and 90%, respectively. They can be determined using a laser particle size analyzer according to GB / T 19077-2016. For the measurement, a clean, small beaker can be used. 1 g of the sample to be tested is placed in the beaker and mixed with 20 ml of deionized water. The sample is then sonicated at 53 kHz / 120 W for 5 minutes to ensure complete dispersion. Afterward, the laser particle size analyzer is switched on, the optical system is cleaned, and the background is automatically measured. The sonicated sample solution is stirred to ensure uniform dispersion, then transferred to the sample chamber according to the requirements, and the particle size measurement is started. A MasterSizer 3000 laser particle size analyzer can be used as the instrument.

[0271] The specific surface area of ​​powder materials can be measured using the nitrogen adsorption surface analysis method according to GB / T 19587-2017 and calculated using the BET (Brunauer-Emmett Teller) method. The Tri-Star 3020 model for specific surface area and pore size analysis from Micromeritics (USA) can be used as the measuring instrument.

[0272] The degree of graphitization of powder materials can be determined using an X-ray diffractometer (e.g., Bruker D8 Discover). The measurement is performed according to JIS K 0131-1996 and JB / T 4220-2011 to determine the mean layer spacing d. 002 to determine the C(002) crystal plane in the crystal structure of the material. The degree of graphitization is then calculated using the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) × 100% is calculated. In this formula, d 002The average layer spacing of the C(002) crystal plane in the crystal structure of the material, expressed in nanometers (nm). A copper target can be used as the anode target for the measurement, with CuKα radiation serving as the radiation source. The wavelength of the radiation λ = 1.5418 Å, the scan angle range (2θ) is between 20° and 80°, and the scan rate is 4° / min.

[0273] The OI value of graphite materials (artificial graphite, natural graphite, etc.) in powder form can be determined using an X-ray diffractometer (e.g., Bruker D8 Discover). The measurement method according to JIS K 0131-1996 and JB / T 4220-2011 can be used to determine the X-ray diffractogram of the powder. The OI value of the powder is calculated using the formula OI = I 004 / I 110 calculated. I 004 I is the integral area of ​​the diffraction peak of the C(004) crystal plane in the powder, and I 110is the integral area of ​​the diffraction peak of the C(110) crystal plane in the powder.

[0274] The OI value of the negative electrode film layer can be measured with an X-ray diffractometer (e.g., Bruker D8 Discover). The measurement can be performed according to the standards JIS K 0131-1996 and JB / T 4220-2011 to obtain the X-ray diffractogram of the negative electrode plate. The OI value is calculated using the formula OI = I 004 / I 110 calculated. I 004 is the integral area of ​​the diffraction peak of the C(004) crystal plane of the negative electrode plate, and I 110 is the integral area of ​​the diffraction peak of the C(110) crystal plane of the negative electrode plate.

[0275] In X-ray diffraction analysis, a copper target can be used as the anode target, with CuKα radiation serving as the radiation source. The wavelength of the radiation λ = 1.5418 Å, the scan angle range (2θ) is between 20° and 80°, and the scan rate is 4° / min.

[0276] Active materials for electrodes (e.g., active materials of the positive and negative electrodes) can be obtained as follows: The battery cell is completely discharged, then the electrode plates are removed and immersed in an organic solvent (e.g., dimethyl carbonate) for a specific time (e.g., 2–10 hours). The electrode plates are then removed and dried at a specific temperature and time (e.g., 60 °C for more than 4 hours). After drying, the electrode plates are removed and baked out at a specific temperature and time (e.g., 400 °C for more than 2 hours). A sample of the active material is taken from any point on the baked-out electrode plates (e.g., by scraping off the powder with a blade).

[0277] The specific surface area of ​​electrode film layers (such as positive and negative electrode film layers) can be measured using the nitrogen adsorption surface analysis method according to GB / T 19587-2017 and calculated using the BET (Brunauer-Emmett-Teller) method. The Tri-Star 3020 model for specific surface area and pore size analysis from Micromeritics (USA) can be used as the measuring instrument. During the test: The battery cell is completely discharged, then the electrode plates are removed and immersed in an organic solvent (e.g., dimethyl carbonate) for a specific period (e.g., 2–10 hours). The electrode plates are then removed and dried at a specific temperature and time (e.g., 60 °C for more than 4 hours). After drying, the electrode plates are removed.A single-sided coated electrode plate is used (for double-sided coated electrode plates, the electrode film layer is first removed from one side). Nitrogen serves as the adsorption gas. Using a surface and pore size analyzer, the adsorption-desorption curve is recorded in the range of a relative pressure P / P0 from 0 to 0.99. The specific surface area of ​​the electrode film layer is calculated using the BET method. P represents the equilibrium adsorption pressure and P0 the saturation vapor pressure.

[0278] The porosity of electrode film layers (e.g., positive and negative electrode film layers) can be tested as follows: The battery cell is completely discharged, then the electrode plates are removed and immersed in an organic solvent (e.g., dimethyl carbonate) for a specific time (e.g., 2–10 hours). The electrode plates are then removed and dried at a specific temperature and time (e.g., 60 °C for more than 4 hours). After drying, the electrode plates are removed. A single-sided coated electrode plate is cut into small, circular samples with a specific area, and the apparent volume V1 of the electrode plate is calculated. According to GB / T24586-2009, an inert gas (such as helium or nitrogen) is used as the medium, and the gas displacement method is applied. The true volume V2 of the electrode plate is determined using a true density meter.Electrode film porosity = (V1 - V2) / V1 × 100%. Several samples (e.g., 30) with good appearance and no powder abrasion at the edges can be tested, and the mean of the results can be determined, which can improve the accuracy of the test results. The Micromeritics AccuPyc II 1340 true density meter can be used as the measuring instrument.

[0279] The density of an electrode film layer (e.g., a positive or negative electrode film layer) is calculated using the formula: Density = Area density of the electrode film layer / Thickness of the electrode film layer. The thickness of the electrode film layer refers to its average thickness. During measurement, multiple locations (e.g., more than 10) can be measured, and the average value then determined.

[0280] The areal density of the electrode film layer can be determined as follows: The battery cell is completely discharged, then the electrode plates are removed and immersed in an organic solvent (e.g., dimethyl carbonate) for a specific time (e.g., 2–10 hours). The electrode plates are then removed and dried at a specific temperature and time (e.g., 60 °C for more than 4 hours). After drying, the electrode plates are removed. A single-sided coated electrode plate (for double-sided coated electrode plates, the electrode film layer is first removed from one side) is cut into a small circular piece with area S1, weighed, and the weight is recorded as M1. The electrode film layer is then removed from the weighed electrode plate, and the electrode current collector is weighed. The weight is recorded as M0.The areal density of the electrode film layer is calculated according to the formula areal density = (M1 - M0) / S1. electrolyte

[0281] In some embodiments, the battery cell further comprises an electrolyte, wherein the electrolyte comprises an organic solvent and an electrolyte salt.

[0282] In some embodiments, the electrolyte salt comprises lithium hexafluorophosphate (LiPF6).

[0283] LiPF6 possesses high ionic conductivity, which contributes to improved charging and discharging performance of battery cells; LiPF6 contributes to the formation of a stable passivation film on the surface of the positive electrode current collector (e.g., aluminum foil) and protects this positive electrode current collector from further oxidation; LiPF6 contributes to the formation of a stable SEI film on the negative electrode, thereby reducing the irreversible consumption of electrolyte and active lithium and improving the first coulomb efficiency and cycle performance of the battery cell; LiPF6 possesses good chemical stability and does not undergo harmful side reactions with active materials of the electrodes, electrolytes, separator films, etc., thus extending the service life of the battery cells.

[0284] In some embodiments, the concentration of the electrolyte salt is 0.8 mol / L to 2 mol / L; for example, it may be 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, or a range formed by any of the above values.

[0285] Optionally, the concentration of the electrolyte salt can be from 0.9 mol / L to 1.3 mol / L.

[0286] In some embodiments, the organic solvent comprises ethylene carbonate (EC) and ethyl methyl carbonate (EMC).

[0287] Ethylene carbonate (EC) possesses a high dielectric constant and preferentially forms stable solvation structures with lithium ions in the electrolyte. Ethylene carbonate (EC) contributes to the formation of a stable SEI film on the negative electrode and improves the high-voltage strength of the electrolyte. This allows for optimal utilization of the high specific capacity of active materials with a high nickel content in the positive electrode and increases the energy density of the battery cells. Ethyl methyl carbonate (EMC) has a low viscosity and a wide liquid temperature range, which improves the wettability of the electrode assemblies by the electrolyte and increases the cycle life of battery cells.Furthermore, ethyl methyl carbonate (EMC) has a wide electrochemical window and high stability at high voltages, which contributes to improving the oxidation stability of battery cells; it also helps to optimally utilize the high specific capacity of high nickel-content active materials in the positive electrode, thereby increasing the energy density of battery cells.

[0288] Optionally, the mass ratio of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) is 20:80 to 70:30; for example, it can be 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, or a range formed by any of the above values.

[0289] Optionally, the mass ratio of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) is 20:80 to 40:60.

[0290] In some embodiments, the organic solvent further comprises one or more of the following substances: propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butyl carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0291] In some embodiments, the electrolyte further comprises fluoroethylene carbonate (FEC), the mass of which is 0.5% to 5% of the total mass of the electrolyte; for example, it may be 0.5%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, or a range formed by any of the above values.

[0292] FEC generates high-quality films, contributing to the formation of a low-resistance, ion-conducting SEI film at the negative electrode. This reduces the energy barrier for lithium ion passage through the SEI film at low temperatures and decreases the accumulation of electrolyte side reaction products. As a result, the internal resistance of the battery cell can be lowered, and the reaction kinetics and cycle performance of the battery cell at low temperatures can be improved.

[0293] In some embodiments, the ratio of the mass of the electrolyte to the capacity of the battery cell is 1 g / Ah to 2 g / Ah.

[0294] The mass of the electrolyte can be determined as follows: The battery cell is weighed and the mass recorded as m0; then the battery cell is disassembled, centrifuged to separate the electrolyte, and all the separated solid components are immersed in acetonitrile solution. After soaking for 2 hours, they are removed, air-dried at room temperature, and then dried in a 60 °C oven for more than 4 hours. Afterward, they are weighed again and the mass recorded as m1. The mass difference between m0 and m1 is taken as the mass of the electrolyte.

[0295] The capacity of a battery cell can be determined as follows: At 25 °C, the battery cell is left to rest for 5 minutes. It is then discharged at a constant current of 0.33 C until the lower cutoff voltage is reached, followed by another 5-minute rest period. Next, it is charged at a constant current of 0.33 C until the upper cutoff voltage is reached, and then charged at a constant voltage at the upper cutoff voltage until the current is ≤ 0.05 C. After another 5-minute rest period, the battery cell is again discharged at a constant current of 0.33 C until the lower cutoff voltage is reached. The measured discharge capacity is recorded and reported as the battery cell's capacity.

[0296] The upper and lower cutoff voltages can correspond to the charging and discharging voltages recommended in the battery cell's product specifications. For example, the upper cutoff voltage of a battery cell can be 4.3 V and the lower cutoff voltage 2.8 V.

[0297] The electrode assembly of the present disclosure can have a wound or a stacked structure. The embodiments of the present disclosure are not limited to this.

[0298] In some embodiments, the battery cell is a pouch battery cell.

[0299] Fig. Figure 7 shows an exploded view of a pouch battery cell 22, which is provided by an exemplary embodiment.

[0300] As in Fig.As shown in Figure 7, the pouch battery cell 22 comprises an electrode assembly 221 and a housing. The housing includes two packaging films 222. The electrode assembly 221 is located between the two packaging films 222. The edges of the two packaging films 222 are joined together to form a seal. The pouch battery cell 22 also includes electrode terminals 223, which extend between the two packaging films 222 and are electrically connected to the electrode assembly 221.

[0301] In some embodiments, the respective packaging film comprises an insulating protective layer, a metal layer and an insulating connecting layer, wherein the insulating connecting layer is arranged on the surface of the metal layer facing the electrode assembly and the insulating protective layer is arranged on the surface of the metal layer facing away from the electrode assembly.

[0302] Optionally, the insulating protective layer can be made of nylon.

[0303] Optionally, the metal layer can be made of aluminum or steel.

[0304] Optionally, the insulating connecting layer can be made of polypropylene.

[0305] In some embodiments, the casing of the pouch battery cell is a pouch-shaped structure made of aluminum-plastic foil.

[0306] In some embodiments, the battery cell is a hard-shell battery cell.

[0307] The casing of a hard-shell battery cell is square and made of metal, for example aluminum or steel.

[0308] The manufacturing process for battery cells is generally known. In some embodiments, a positive electrode plate, a separator film, a negative electrode plate, and an electrolyte can be assembled to form a battery cell. For example, the positive electrode plate, the separator film, and the negative electrode plate can be assembled into an electrode assembly, which is then placed in a housing, filled with electrolyte, and subjected to processes such as standing and formation to obtain a battery cell. Examples of implementation

[0309] The following embodiments describe the content of this disclosure in detail. These embodiments serve only for illustration, as various modifications and changes within the scope of this disclosure are obvious to those skilled in the art. Unless otherwise stated, all proportions, percentages, and ratios given in the following embodiments refer to weight; all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further preparation; and the equipment used in the embodiments is commercially available. Example 1: Production of the positive electrode plate

[0310] The active material of the positive electrode is LiNi 0,92 Co 0,04 Mn 0,04Oxygen (O2), carbon black (the conductive material for the positive electrode), and polyvinylidene fluoride (PVDF) (the binder for the positive electrode) are mixed in a mass ratio of 98:1:1. With the addition of N-methylpyrrolidone (NMP), the mixture is stirred in a vacuum stirring system until a homogeneous mass is obtained, thus yielding the positive electrode paste. The positive electrode paste is applied evenly to both sides of the aluminum foil of the positive electrode current collector, dried at room temperature, and then further dried in an oven. After cold rolling and cutting, the positive electrode plate is obtained.

[0311] The active material of the positive electrode has a single-crystal morphology and a volumetric distribution particle diameter Dv50 of 2 µm. Production of the negative electrode plate

[0312] The first active material of the negative electrode, the negative electrode binder polyvinyl alcohol, and the negative electrode conductor SP-Li are thoroughly mixed in a mass ratio of 90:5:5 in a deionized water-solvent system and shot-milled to obtain the first negative electrode paste. The second active material of the negative electrode, the negative electrode binder polyvinyl alcohol, and the negative electrode conductor SP-Li are thoroughly mixed in a mass ratio of 90:5:5 in a deionized water-solvent system and shot-milled to obtain the second negative electrode paste.The second negative electrode paste is applied evenly to both sides of the copper foil of the negative electrode current collector, and the first negative electrode paste is applied evenly over the second negative electrode paste, dried at room temperature, and then further dried in an oven. After cold rolling and cutting, the negative electrode plate is obtained.

[0313] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 6%.

[0314] The second active material of the negative electrode is synthetic graphite.

[0315] The mass fraction of the Si element in the entire negative electrode film layer is 3%. Production of the separator film

[0316] Aluminum oxide, polyacrylate binder, and sodium carboxymethylcellulose dispersant are mixed in deionized water at a solids mass ratio of 60:30:10 with stirring to obtain a coating paste. A standard 7 µm thick polyethylene film is used as the base film. The prepared coating paste is applied evenly to both sides of the base film. After drying and cutting, the separator film is obtained.

[0317] The thickness of both the first and second porous coatings is 1 µm. Aluminum oxide is an aggregate of primary particles, and the spaces between the primary particles that make up the aggregate form pores. Production of the electrolyte

[0318] At 25 °C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent. Fluoroethylene carbonate (FEC) and LiPF6 are then added and thoroughly stirred to obtain the electrolyte. The concentration of LiPF6 is 1 mol / L, and the mass of FEC is 3% of the total mass of the electrolyte. Production of battery cells

[0319] The layers are arranged in the sequence "separator foil - negative electrode plate - separator foil - positive electrode plate". One end each of the positive and negative electrode plates and the separator foil is attached to the dispensing reel, while the other end is stacked on top of each other and fixed to the winding shaft. A motor rotates the winding shaft to wind the positive electrode plate, the negative electrode plate, and the separator foil. The wound structure is then hot-pressed to form a coiled electrode assembly. This assembly is placed in an aluminum casing, electrolyte is added, and after processes such as encapsulation, settling, and formation, a battery cell is obtained. Comparative example 1

[0320] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the separator film

[0321] Aluminum oxide, the binder polyacrylate, and the dispersant sodium carboxymethylcellulose are mixed uniformly in deionized water at a solids mass ratio of 60:30:10 with stirring to obtain a coating paste. A commercially available polyethylene film with a thickness of 7 µm is used as the base film. The prepared coating paste is applied evenly to one surface of the base film. After drying and cutting, the separator film is obtained. The coating of the separator film faces the positive electrode plate. Aluminum oxide is an aggregate of primary particles, and the spaces between the primary particles that make up the aggregate form pores. Comparative example 2

[0322] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0323] The active material of the negative electrode (artificial graphite), the binder of the negative electrode (polyvinyl alcohol), and the conductive material of the negative electrode (SP-Li) are thoroughly mixed in a mass ratio of 90:5:5 in a deionized water-solvent system and shot-milled to obtain the negative electrode paste. The negative electrode paste is applied evenly to both sides of the copper foil of the negative electrode current collector, dried at room temperature, and then further dried in an oven. After cold rolling and cutting, the negative electrode plate is obtained. Comparative example 3

[0324] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0325] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 24%.

[0326] The second active material of the negative electrode is synthetic graphite.

[0327] The mass fraction of the Si element in the entire negative electrode film layer is 12%. Performance tests(1) Test of the DC resistance (DCR) of the battery cell

[0328] The battery cell is stored at -25 °C until it reaches a stable state. It is then charged with a constant current of 1 C to 4.3 V and subsequently charged with a constant voltage until the current is ≤ 0.05 C. At this point, the battery cell is at a state of charge (SOC) of 100%. The battery cell is then discharged with a constant current of 1 C over a specified period to bring it down to a state of charge of 10% SOC. The voltage of the battery cell at this point is recorded as U1. The battery cell is then discharged with a constant current of 4 C for 30 seconds, with a sampling interval of 0.1 seconds. The voltage at the end of the discharge is recorded as U2. The DC resistance of the battery cell is calculated using the formula DCR = (U1 - U2) / 4 C. (2) Testing the cycle performance of the battery cell

[0329] The battery cell is stored at -10 °C until it reaches a stable state. It is then charged with a constant current of 1 C to 4.3 V and subsequently charged with a constant voltage until the current is ≤ 0.05 C. After a 5-minute rest period, the battery cell is discharged with a constant current of 1 C down to the cutoff voltage of 2.8 V to maintain the discharge capacity of the first cycle. This charge and discharge process is repeated. Battery cell capacity retention rate after 1000 cycles = Discharge capacity in the 1000th cycle / Discharge capacity of the first cycle * 100%. (3) Test of the energy density of the battery cell

[0330] At 25 °C, the battery cell is left to rest for 5 minutes. It is then discharged to 2.8 V at a constant current of 0.33 C, followed by another 5-minute rest period. Next, it is charged to 4.3 V at a constant current of 0.33 C, and then charged at a constant voltage until the current is ≤ 0.05 C. After another 5-minute rest period, the battery cell is again discharged to 2.8 V at a constant current of 0.33 C. The discharge energy E0 is recorded. The apparent volume of the battery cell is denoted V0. The volumetric energy density of the battery cell is calculated using the formula Volumetric Energy Density = E0 / V0, with the unit Wh / L. Table 1 Serial No. Filler particles of the separator film Separator film Negative electrode film layer Positive electrode active material electrolyte -25 °C / 10 %SOC / DCR(mΩ) Capacity maintenance rate after 1000 cycles at -10 °C Dv50(µm) BET(m 2 / g) Porosity at 25 °C Porosity at -25 °C Mass fraction of Si Dv50(µm) FEC mass content Implementation example 1 0,5 180 49 % 33 % 3% 2 3% 6,5 91,3 % Comparative example 1 0,5 180 51% 29 % 3% 2 3% 10,6 85,3 % Comparative example 2 0,5 180 49 % 33 % 0 2 3% 11,5 84,8 % Comparative example 3 0,5 180 49 % 33 % 12 % 2 3% 13,4 81,3 %

[0331] Fig. Figure 8 shows a scanning electron microscope image of the negative electrode plate produced in embodiment 1. Fig.Figure 9 shows a scanning electron microscope image of the separator film produced in embodiment 1.

[0332] The test results of embodiment 1 and comparative examples 1 to 3 show that the present disclosure can reduce the internal resistance of the battery cell at low temperatures, improve the performance of the battery cell at low temperatures and low state of charge (SOC), and achieve good cycle performance of the battery cell at low temperatures by matching the negative electrode and the separator film of the battery cell, wherein the first negative electrode film layer, which is located away from the negative electrode current collector, comprises a first silicon-based material and a first carbon-based material, whereby the mass fraction of the Si element in the negative electrode film layer is 0.5% to 6%, and by arranging a first porous coating and a second porous coating containing filler particles on both sides of the base film.

[0333] In comparative example 1, the base film is coated only on the side facing the positive electrode plate. At low temperatures, the pore size of the uncoated surface of the base film decreases significantly or even closes completely. This results in high through-resistance for lithium ions during discharge of the battery cell at low temperatures and high internal resistance of the battery cell at low temperatures. Simultaneously, the separator film's ability to retain electrolyte is relatively poor. The volume expansion of the negative electrode initially compresses the base film and forces out the electrolyte stored in its pores, creating local areas of dry electrolyte within the base film. Consequently, both the battery cell's performance at low temperatures and low states of charge (SOC) and its cycle performance at low temperatures are poor.

[0334] In comparative example 2, the negative electrode film layer contains no silicon element, resulting in poor reaction kinetics of the battery cell at low temperatures and a large gap between the inner interfaces of the electrode plates. This, in turn, impairs the battery cell's performance at low temperatures and low states of charge (SOC), as well as its cycle performance at low temperatures.

[0335] In comparative example 3, the mass fraction of the silicon element in the negative electrode film layer is too high, leading to an inadequate match between the negative electrode and the separator film. The volume expansion of the negative electrode compresses the separator film and forces out the electrolyte stored in the pores of the separator film, creating local areas of dry electrolyte within the separator film. Consequently, both the battery cell's performance at low temperatures and low states of charge (SOC) and its cycle performance at low temperatures are poor. Example 1-1

[0336] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0337] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 1%.

[0338] The second active material of the negative electrode is synthetic graphite.

[0339] The mass fraction of the Si element in the entire negative electrode film layer is 0.5%. Example 1-2

[0340] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0341] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 3%.

[0342] The second active material of the negative electrode is synthetic graphite.

[0343] The mass fraction of the Si element in the entire negative electrode film layer is 1.5%. Example 1-3

[0344] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0345] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 5%.

[0346] The second active material of the negative electrode comprises silicon oxide material and synthetic graphite. The mass fraction of the silicon element in the first negative electrode film layer is 1%.

[0347] The mass fraction of the Si element in the entire negative electrode film layer is 3%. Exemplary embodiment 1-4

[0348] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0349] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 8%.

[0350] The second active material of the negative electrode comprises silicon oxide and synthetic graphite. The mass fraction of the silicon element in the first negative electrode film layer is 2%.

[0351] The mass fraction of the Si element in the entire negative electrode film layer is 5%. Example 1-5

[0352] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the negative electrode plate

[0353] The first active material of the negative electrode comprises silicon oxide and synthetic graphite with a carbon coating. The mass fraction of silicon in the first negative electrode film layer is 8%.

[0354] The second active material of the negative electrode comprises silicon oxide material and synthetic graphite. The mass fraction of the silicon element in the first negative electrode film layer is 4%.

[0355] The mass fraction of the Si element in the entire negative electrode film layer is 6%. Table 2 Serial No. First negative electrode film layer Second negative electrode film layer Negative electrode film layer Volumetric energy density (Wh / L) -25 °C / 10 % SOC / DCR (mΩ) Capacity retention rate after 1000 cycles at -10 °C Mass fraction of Si Mass fraction of Si Mass fraction of Si Example 1-1 1% 0 % 0,5 % 687 8,8 89,3 % Example 1-2 3 % 0 % 1,5 % 700 7,5 90,6 % Example 1 6% 0 % 3 % 710 6,5 91,3 % Example 1-3 5% 1% 3 % 710 6,9 90,3 % Exemplary embodiment 1-4 8% 2% 5% 722 6,3 88,9 % Example 1-5 8% 4% 6% 726 6,3 87,5 %

[0356] The test results indicate that by further adjusting the mass fraction of the Si element in the negative electrode film layer, the battery cell can simultaneously achieve high energy density, low internal resistance and good cycle performance at low temperatures. Example 2-1

[0357] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the positive electrode plate

[0358] The active material of the positive electrode has a single-crystal morphology and a volumetric distribution particle diameter Dv50 of 3 µm. Example 2-2

[0359] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the positive electrode plate

[0360] The active material of the positive electrode has a single-crystal morphology and a volumetric distribution particle diameter Dv50 of 4.5 µm. Example 2-3

[0361] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the positive electrode plate

[0362] The active material of the positive electrode has a single-crystal morphology and a volumetric distribution particle diameter Dv50 of 6 µm. Example 2-4

[0363] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the positive electrode plate

[0364] The active material of the positive electrode has a single-crystal morphology and a volumetric distribution particle diameter Dv50 of 7 µm. Table 3 Serial No. Positive electrode active material -25 °C / 10 % SOC / DCR(mΩ) Capacity retention rate after 1000 cycles at -10 °C Dv50 (µm) Example 1 2 6,5 91,3 % Example 2-1 3 6,9 90,8 % Example 2-2 4,5 7,5 90,2 % Example 2-3 6 8,1 89,5 % Example 2-4 7 9,4 86,7 %

[0365] The test results show that the smaller particle size of the active material in the positive electrode enables a faster solid-state diffusion rate of lithium ions and lower concentration polarization. This allows the battery cell to achieve lower internal resistance and good cycle performance at low temperatures. Example 3-1

[0366] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the electrolyte

[0367] At 25 °C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent. LiPF6 is then added and the mixture is thoroughly stirred to obtain the electrolyte. The concentration of LiPF6 is 1 mol / L. Example 3-2

[0368] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the electrolyte

[0369] At 25 °C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent. Fluoroethylene carbonate (FEC) and LiPF6 are then added and thoroughly stirred to obtain the electrolyte. The concentration of LiPF6 is 1 mol / L, and the mass of FEC is 0.5% of the total mass of the electrolyte. Example 3-3

[0370] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the electrolyte

[0371] At 25 °C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent. Fluoroethylene carbonate (FEC) and LiPF6 are then added and thoroughly stirred to obtain the electrolyte. The concentration of LiPF6 is 1 mol / L, and the mass of FEC is 5% of the total mass of the electrolyte. Example 3-4

[0372] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the electrolyte

[0373] At 25 °C, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 30:70 to obtain an organic solvent. Fluoroethylene carbonate (FEC) and LiPF6 are then added and thoroughly stirred to obtain the electrolyte. The concentration of LiPF6 is 1 mol / L, and the mass of FEC is 8% of the total mass of the electrolyte. Table 4 Serial No. electrolyte -25 °C / 10 % SOC / DCR(mΩ) Capacity maintenance rate after 1000 cycles at -10 °C FEC mass fraction Example 3-1 0 8,6 87,9 % Example 3-2 0,5 % 8,2 88,6 % Example 1 3 % 6,5 91,3 % Example 3-3 5% 6,9 90,7 % Example 3-4 8% 9,2 86,1 %

[0374] The test results show that an appropriate amount of FEC promotes the formation of a low-resistance, ion-conducting SEI film at the negative electrode. This reduces the energy barrier for the passage of lithium ions through the SEI film at low temperatures and decreases the accumulation of electrolyte by-reaction products. As a result, the battery cell can achieve lower internal resistance and good cycle performance at low temperatures. Example 4-1

[0375] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the separator film

[0376] The thickness of both the first and second porous coatings is 0.7 µm. Example 4-2

[0377] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the separator film

[0378] The thickness of both the first and second porous coatings is 2 µm. Table 5 Serial No. Thickness of the first porous coating (µm) Thickness of the first porous coating (µm) Separator film -25 °C / 10 % SOC / DCR (mΩ) Capacity maintenance rate after 1000 cycles at -10 °C Porosity at 25 °C Porosity at -25 °C Example 4-1 0,7 0,7 50 % 30 % 7,1 90,5 % Example 1 1 1 49 % 33 % 6,5 91,3 % Example 4-2 2 2 45 % 35 % 8,1 88,7 %

[0379] The test results suggest that by further adjusting the thickness of the coating, the battery cell can simultaneously achieve high energy density, low internal resistance and good cycle performance at low temperatures. Example 5-1

[0380] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the separator film

[0381] Calcium oxide, the binder polyacrylate, and the dispersant sodium carboxymethylcellulose are mixed in deionized water at a solids mass ratio of 60:30:10 with stirring to obtain a coating paste. A standard polyethylene film with a thickness of 7 µm is used as the base film. The prepared coating paste is applied evenly to both sides of the base film. After drying and cutting, the separator film is obtained.

[0382] The thickness of both the first and second porous coatings is 1 µm. Calcium oxide is an aggregate of primary particles, and the spaces between the primary particles that make up the aggregate form pores. Table 6 Serial No. Filler particles of the separator film Separator film -25 °C / 10 % SOC / DCR (mΩ) Capacity retention rate after 1000 cycles at -10 °C type Dv50(µm) BET(m 2 / g) Porosity at 25 °C Porosity at -25 °C Implementation example 1 Aluminum oxide 0,5 180 49 % 33 % 6,5 91,3 % Implementation example 5-1 Calcium oxide 0,5 60 44 % 30 % 10,0 86,2 %

[0383] The test results show that increasing the specific surface area of ​​the filler particles helps to reduce the internal resistance of the battery cell at low temperatures and to improve its cycle performance at low temperatures. Example 6-1

[0384] Except for the following differences, the manufacturing process of the battery cells is identical to that in embodiment 1. Production of the separator film

[0385] Aluminum oxide, polyacrylate binder, and sodium carboxymethylcellulose dispersant are mixed uniformly in deionized water at a solids mass ratio of 60:30:10 while stirring to obtain a coating paste. The polymer binder particles (oil-containing polyvinylidene fluoride particles), the binder (polyacrylate), and the dispersant (sodium carboxymethylcellulose) are mixed in deionized water at a solids mass ratio of 60:30:10 and thoroughly stirred to obtain the adhesive layer paste. A commercially available 7 µm thick polyethylene film is used as the base film. The prepared coating paste is applied evenly to both sides of the base film. After drying, the adhesive layer paste is applied, dried again, and finally cut to size to obtain the separator film.

[0386] The thickness of both the first and second porous coatings is 1 µm. Aluminum oxide is an aggregate of primary particles, and the spaces between the primary particles that make up the aggregate form pores. Table 7 Serial No. Separator film -25 °C 10 % SOC / DCR(mΩ) Capacity maintenance rate after 1000 cycles at -10 °C Porosity at 25 °C Porosity at -25 °C Example 1 49% 33 % 6,5 91,3 % Example 6-1 47 % 32 % 6,8 92,2 %

[0387] The test results show that polymer binder particles have a binding property that enables a firm connection of the electrode plates, reduces the gap between the electrode plates, improves the wettability of the electrode plates by the electrolyte and thus improves the cycle performance of the battery cells at low temperatures.

[0388] It should be noted that this disclosure is not limited to the embodiments described above. The embodiments described above serve only as examples. All embodiments that, within the framework of the technical concept of this disclosure, have essentially the same structure and achieve the same effect fall within the scope of protection of this disclosure. Furthermore, without deviating from the essence of this disclosure, various modifications of the embodiments that are obvious to a person skilled in the art, as well as other configurations formed by combining parts of the embodiments, are also included within the scope of protection of this disclosure. Reference symbol list: 100 battery-powered device; 10 cases; 11 first case; 12 second case; 121 Carrier plate; 122 frames; 13 connecting beams; 20 battery cell assembly; 30 Thermal management component; 40 adhesives for fixing; 22 battery cells; 23 Recording housings; 24 positive electrode plates; 240 positive electrode current collector; 241 positive electrode film layer; 25 negative electrode plates; 250 negative electrode film layer; 251 first negative electrode film layer; 252 second negative electrode film layer; 26 separator film; 260 base film; 261 first porous coating; 262 second porous coating; 263 Adhesive layer; X first direction; Z second direction; Y third direction. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] JIS K 0131-1996

[0272] JB / T 4220-2011 [0272, 0274] JIS K 0131-1996 and JB / T 4220-2011

[0273] Standards JIS K 0131-1996

[0274]

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