Secondary battery and power-consuming device

Abstract

Secondary battery comprising a cathode foil, an anode foil and a separating film, wherein, the cathode foil comprises a cathode collector and a cathode film layer arranged on the surface of at least one side of the cathode collector, wherein the density of the cathode film layer is 2.0 g / cm³ 3 up to 3.0 g / cm³ 3 amounts; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector, wherein the density of the anode film layer is 1.4 g / cm³ 3 up to 1.85 g / cm³ 3 amounts; wherein the separating film comprises a base film having a thickness of 4 µm to 12 µm, wherein the base film has nanopores having an average pore size of 10 nm to 300 nm.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] The present disclosure is based on the Chinese patent application with application number 202510932503.0, the filing date of July 7, 2025, and the title "Secondary battery and power-consuming device," and claims priority from the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated into the present disclosure by reference. TECHNICAL AREA

[0002] The present disclosure relates to the technical field of batteries, in particular a secondary battery and a power-consuming device. STATE OF THE ART

[0003] In recent years, secondary batteries have found widespread use in energy storage systems such as hydropower, thermal, wind and solar power plants, as well as in numerous fields including power tools, electric bicycles, electric motorcycles, electric vehicles and aerospace.

[0004] With the significant advancements in secondary batteries, practical applications now place higher demands on the energy density and safety performance of the secondary battery.

[0005] In related technologies, increasing the energy density of batteries is often achieved by increasing the packing density of the film layer. However, this approach has a significant drawback: while the packing density is increased, heat dissipation within the battery also increases, thereby impairing the battery's safety performance.

[0006] Therefore, striking a balance between the energy density of batteries and their safety performance has become an urgent technical challenge. CONTENT OF THE PRESENT INVENTION

[0007] The present disclosure relates to the aforementioned subject matter of investigation and aims to provide a secondary battery and a power-consuming device. This secondary battery achieves both a high energy density and improved safety performance.

[0008] To achieve the above objective, a first aspect of the present disclosure provides a secondary battery comprising a cathode foil, an anode foil and a separating film, wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on the surface of at least one side of the cathode collector, wherein the density of the cathode film layer is 2.0 g / cm³3 up to 3.0 g / cm³ 3 is; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector, wherein the density of the anode film layer is 1.4 g / cm³ 3 up to 1.85 g / cm³ 3 is; wherein the separating film comprises a base film having a thickness of 4 µm to 12 µm, wherein the base film has nanopores having an average pore size of 10 nm to 300 nm.

[0009] In the present disclosure, the control of the pressure density of the cathode film layer between 2.0 g / cm² is facilitated. 3 and 3.0 g / cm² 3 and the anode film layer between 1.4 g / cm² 3 and 1.85 g / cm² 3Achieving a high battery energy density. The base film used in this disclosure, with a thickness of 4 µm to 12 µm, mitigates the adverse effects on battery safety performance caused by a base film that is too thin (less than 4 µm) and simultaneously reduces the adverse effects on battery energy density caused by a base film that is too thick (more than 12 µm). This configuration improves battery safety performance while ensuring high energy density. Furthermore, the base film features nanopores with an average pore size of 10 nm to 300 nm. This enables an improved lithium-ion migration rate and simultaneously suppresses the growth of lithium dendrites, further enhancing battery safety performance.

[0010] In particular, the base film within the aforementioned thickness range can maintain its structural stability at elevated temperatures, thus effectively reducing the risk of a short circuit between the positive and negative electrodes. Specifically, in the event of thermal runaway, the stable structure of the base film can suppress the occurrence of side reactions through physical insulation. This lowers the peak temperature of thermal runaway in the battery, reduces the risk of thermal spread, and improves the battery's safety performance. Furthermore, within the aforementioned thickness range, the base film helps to mitigate the adverse effects on the battery's energy density, thereby facilitating the maintenance of a high energy density.

[0011] In some embodiments, the base film has a thickness of 5 µm to 9 µm. This thickness range of the base film ensures a further balance between the energy density of the battery and its safety performance.

[0012] In some embodiments, the base film exhibits a porosity of 20% to 70%. This enables an improved lithium-ion migration rate while simultaneously suppressing the growth of lithium dendrites, further enhancing the battery's safety performance.

[0013] In some embodiments, the separating film further comprises a coating arranged on at least one side of the base film, wherein the coating includes heat-resistant particles woven into a porous structure. Compared to coatings without such a porous structure, the heat-resistant particles in this embodiment are woven into a porous structure, which allows for less obstruction of ion transport by the coating, thereby improving ion transport efficiency. Furthermore, the coating comprises heat-resistant particles that exhibit only minimal volume changes under temperature fluctuations. Applying this heat-resistant, particle-containing coating to the surface of the base film suppresses the thermal shrinkage rate of the base film. This reduces the risk of a short circuit between the positive and negative electrodes and thus improves the battery's safety performance.

[0014] In some embodiments, the coating applied to at least one side of the base film has a thickness of 0.011 µm to 3 µm. This makes it easier for the battery to achieve a high energy density and, at the same time, allows the coating to suppress the thermal shrinkage rate of the base film more effectively, thereby further improving the battery's safety performance.

[0015] In some embodiments, the heat-resistant particles have an average particle size of 5 nm to 185 nm. These heat-resistant particles can form a coating with a stable support network structure. This structure not only supports the base film but also suppresses thermal shrinkage of the base film, thereby improving the battery's safety performance.

[0016] In some embodiments, the particle surface density of the heat-resistant particles is 0.5 mg / 1540.25 cm². 2 up to 2.5 mg / 1540.25 cm 2 This facilitates the achievement of a high energy density in the battery and allows the heat-resistant particles to effectively suppress the thermal shrinkage of the base film, thereby improving the battery's safety performance.

[0017] In some embodiments, the heat-resistant particles include first heat-resistant particles along the thickness direction of the base film. These first heat-resistant particles are distributed on the surface of the base film and can directly suppress thermal shrinkage of the base film. This further improves the battery's safety performance while maintaining its energy density.

[0018] In some embodiments, the heat-resistant particles comprise first and second heat-resistant particles along the thickness direction of the base film. The first heat-resistant particles are distributed across the surface of the base film, while the second heat-resistant particles are stacked on the side of the first heat-resistant particles facing away from the base film. In this implementation, the stacking arrangement of the first and second heat-resistant particles along the thickness direction of the base film facilitates the formation of a thicker coating. This thicker coating acts as a more effective physical barrier, reducing chemical erosion of the base film by the electrolyte solution and simultaneously mitigating friction from the electrode foils (cathode foil, anode foil). This further improves the battery's safety performance.

[0019] In some embodiments, the heat-resistant particles comprise inorganic particles and bonding particles. In this implementation, the bonding particles act as bridges, firmly connecting the inorganic particles. This creates a stable, integrated structure for the inorganic particles, thereby improving the mechanical strength and stability of the coating. Consequently, the coating better suppresses the thermal shrinkage of the base film.

[0020] In some embodiments, the heat-resistant particles comprise inorganic particles and a bonding layer applied to at least a portion of the surface of the inorganic particles. In this implementation, the bonding layer is applied to the surface of the inorganic particles, thereby enabling increased bonding strength between the inorganic particles and the base film. This reduces the risk of inorganic particle detachment and contributes to improved safety performance and battery lifespan.

[0021] In some embodiments, the inorganic particles comprise at least one compound from the group consisting of aluminum trioxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, boehmite, magnesium oxide, zinc oxide, barium sulfate, magnesium nitride, and barium titanate. These substances exhibit only small volume changes under temperature fluctuations. Their use as inorganic particles further suppresses the thermal shrinkage of the base film and thereby improves the battery's safety performance.

[0022] In some embodiments, the mass fraction of inorganic particles in the coating ranges from 5% to 30%. This makes it easier for the inorganic particles to form a heat-resistant skeletal structure within the coating, effectively suppressing thermal shrinkage of the coating, improving the battery's safety performance, and simultaneously reducing the risk of inorganic particles detaching.

[0023] In some embodiments, the anode film layer comprises a first film layer and a second film layer arranged between the first film layer and the anode collector, wherein the first film layer comprises a first active anode material comprising a first graphite material, wherein the I D / I G -ratio of the first graphite material is 0.4 to 0.9; wherein the second film layer comprises a second active anode material which comprises a second graphite material, wherein the I D / I G -ratio of the second graphite material is 0.05 to 0.2; where I D for the intensity of the D-peak of the Raman spectrum at 1350±50 cm -1 and I G for the intensity of the G-peak of the Raman spectrum at 1580±50 cm -1 stands.

[0024] The I D / I GThe ratio of the first graphite material used in the present disclosure is 0.4 to 0.9, indicating the presence of numerous surface defects on the first graphite material. These defects serve as additional active sites for lithium ion intercalation. The arrangement of this first graphite material with numerous surface defects in the outer layer (first film layer) of the anode foil facilitates an increased probability of contact between these additional active sites and the electrolyte solution, thereby improving the fast-charging capability of the battery. Based on this, a second graphite material with a ratio of I is used for the inner layer (second film layer) of the anode foil. D / I GA ratio of 0.05 to 0.2 is used. This second graphite material has fewer surface defects and a relatively intact structure, which helps to reduce the irreversible loss of lithium ions and thus extend the battery's lifespan.

[0025] In some embodiments, the first active anode material further comprises an anode coating layer distributed on the surface of the first graphite material, which includes amorphous carbon. The structure of amorphous carbon is relatively loose and exhibits numerous porous structures. These pores provide additional diffusion pathways for lithium ions and shorten their diffusion path within the electrode material. By arranging amorphous carbon on the surface of the first graphite material, lithium ions can penetrate the anode coating layer more quickly to reach the interior of the first graphite material, thereby improving the fast-charging capability of the battery.

[0026] In some embodiments, the anode coating layer has a thickness of 10 nm to 100 nm. Maintaining this thickness range for the anode coating layer makes it easier for the secondary battery to achieve a balance between fast-charging capability and energy density.

[0027] In some embodiments, the second film layer further comprises a first graphite material. The first graphite material can improve the battery's fast-charging capability. In this embodiment, the arrangement of both the second and first graphite materials within the second film layer facilitates the simultaneous improvement of the battery's fast-charging capability.

[0028] In some embodiments, the mass ratio of the second graphite material to the first graphite material in the second film layer is (3-5):(5-7). Controlling the mass ratio of the second graphite material to the first graphite material in the second film layer within the above-mentioned range facilitates the simultaneous improvement of fast-charging capability and battery lifespan.

[0029] In some embodiments, the coating weight of the anode film layer is 80 mg / 1540.25 mm². 2 up to 170 mg / 1540.25 mm 2 This allows for an increase in the number of lithium ions released per unit area of ​​the anode film layer, thereby improving the energy density of the battery.

[0030] In some embodiments, the thickness of the anode film layer arranged on one side of the anode collector is 40 µm to 75 µm. This allows the anode film layer to achieve both high capacity and good lithium-ion and electron transport properties, enabling the secondary battery to achieve a balance between high energy density and fast-charging capability.

[0031] In some embodiments, the anode collector has a thickness of 4 µm to 8 µm. This thickness range of the anode collector allows the battery to achieve a high energy density and also helps to reduce the risk of cracks in the anode collector, thereby extending the battery's lifespan.

[0032] In some embodiments, the cathode film layer comprises an active cathode material, which in turn comprises a first active cathode material, wherein the first active cathode material comprises a lithium-containing phosphate with an olivine structure. The lithium-containing phosphate with an olivine structure exhibits a stable three-dimensional lattice structure. During lithium ion insertion and removal, this structure maintains relative stability and resists structural breakdown or deformation. Consequently, the lithium-containing phosphate with an olivine structure can withstand multiple charge and discharge cycles without damage, thereby extending the battery's service life.

[0033] In some embodiments, the lithium-containing phosphate with an olivine structure comprises a compound represented by formula (I): LiFe 1-x-y Mn x M 1 y PO4, Formula (I); where in formula (I) M 1 At least one element from the group consisting of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb is present; where 0 ≤ x ≤ 1 and 0 ≤ y < 1. The lattice structure of the lithium-containing phosphate is stable and resistant to phase transitions, further improving the safety performance of the secondary battery.

[0034] In some embodiments, the first active cathode material further comprises a cathode coating layer arranged on at least a part of the surface of the lithium-containing phosphate, wherein the cathode coating layer comprises at least one of a fast ion conductor material and a carbon material.

[0035] The carbon material is loosely porous, which allows for thorough and effective contact between the electrolyte solution and the lithium iron phosphate matrix. This improves the wetting performance of the electrolyte solution on the cathode film layer and thus the fast-charging capability of the secondary battery.

[0036] The fast-ion conductor material exhibits high ion conductivity. Selecting a cathode coating layer containing this fast-ion conductor material enables improved fast-charging capability of the battery.

[0037] In some embodiments, the mass ratio of the fast-ion conductor material to the carbon material in the cathode coating layer is (0-100):(100-0). Controlling the mass ratio of the fast-ion conductor material to the carbon material within the aforementioned range enables improved fast-charging capability of the battery.

[0038] In some embodiments, the cathode coating layer comprises a first coating layer and a second coating layer; the first coating layer comprises a fast-ion conductor material and the second coating layer comprises a carbon material; the first coating layer is positioned between the lithium-containing phosphate and the second coating layer; the carbon materials typically exhibit better bonding properties. In this embodiment, applying the second coating layer, which contains carbon material, to the outer surface of the first active cathode material improves the bond strength between the first active cathode material and the current collector. During battery operation, this reduces the risk of the first active cathode material detaching, thereby extending the battery's lifetime.

[0039] In some embodiments, the cathode coating layer comprises a first coating layer and a second coating layer; wherein the first coating layer comprises a fast-ion conductor material and the second coating layer comprises a carbon material; wherein the second coating layer is arranged between the lithium-containing phosphate and the second coating layer. In this embodiment, during ion conduction, the lithium ions first penetrate the first coating layer, which is formed from the fast-ion conductor material, then enter the second coating layer, and finally diffuse into the lithium-containing phosphate. This facilitates accelerated lithium ion migration within the first active cathode material and thereby improves the fast-charging capability of the battery.Furthermore, the carbon material in the second coating layer exhibits excellent electrical conductivity and forms a continuous conductive network between the lithium-containing phosphate and the first coating layer to accelerate electron conduction. This further improves the battery's fast-charging capability.

[0040] In some embodiments, the rapid ion conductor material comprises a compound represented by formula (II):

[0041] Li 3-b Fe 2-b M 2 b (PO4)3, Formula (II); where in Formula (II) M 2 At least one element from the group consisting of Ti, Zr, Hf, Ge, and Sn is used, where 0 ≤ b ≤ 1. The aforementioned fast-ion conductor material exhibits excellent ionic conductivity. The selection of this fast-ion conductor material further improves the battery's fast-charging capability.

[0042] In some embodiments, the mass fraction of carbon in the first active cathode material is 1% to 1.5%. This makes it easier for the first active cathode material to achieve a high capacity, allowing the secondary battery to achieve a high energy density. Furthermore, it improves the electronic conductivity of the first active cathode material, thereby enhancing the fast-charging capability of the lithium-ion secondary battery.

[0043] In some embodiments, the BET-specific surface area of ​​the first active cathode material is 12 m². 2 / g up to 16 m 2This allows the surface of the first active cathode material to provide a greater number of lithium-ion insertion and removal pathways. During fast charging, lithium ions can traverse these pathways more quickly to be inserted into the first active cathode material, thereby reducing both the transport distance and the resistance of the lithium ions, thus improving the battery's fast-charging capability.

[0044] In some embodiments, the bulk density of the first active cathode material is 0.8 g / cm³. 3 up to 1.3 g / cm³ 3 This facilitates the formation of numerous porous structures within the cathode film layer and ensures that the battery has superior fast-charging capability.

[0045] In some embodiments, the volume-averaged particle size Dv50 of the first active cathode material is 1 µm to 3 µm. This facilitates the formation of numerous porous channel structures between the particles of the first active cathode material, improves the lithium ion and electron transport properties within the cathode film layer, and thereby improves the kinetic performance of the secondary battery.

[0046] In some embodiments, the compression density of the first active cathode material at 50,000 N is 2.4 g / cm³. 3 up to 2.6 g / cm³ 3 This results in a denser contact between the particles of the first cathode material, thereby improving the energy density of the battery.

[0047] In some embodiments, the active cathode material further comprises a second active cathode material, which includes a lithium transition metal oxide. The lithium transition metal oxide exhibits a higher specific capacity. The selection of the lithium transition metal oxide as the second active cathode material enables a further improvement in the energy density of the secondary battery.

[0048] In some embodiments, the mass ratio of the first active cathode material to the second active cathode material is (99-90):(1-10). This allows for a balance between the lifetime and energy density of the secondary battery.

[0049] In some embodiments, the thickness of the cathode film layer arranged on one side of the cathode collector is 100 µm to 200 µm. This allows the cathode film layer to achieve both high capacity and good lithium-ion and electron transport properties, enabling the secondary battery to achieve a balance between high energy density and fast-charging capability.

[0050] In some embodiments, the coating weight of the cathode film layer arranged on one side of the cathode collector is 200 mg / 1540.25 mm². 2 up to 400 mg / 1540.25 mm 2 This allows for an increase in the number of lithium ions released per unit area of ​​the cathode film layer, thereby improving the energy density of the battery.

[0051] In some embodiments, the density of the cathode film layer is 2 g / cm³. 3 up to 3 g / cm² 3This makes it easier for the cathode film layer to maintain a better porous structure, reduce its tortuosity, and shorten the lithium-ion transport pathways. This improves the fast-charging capability and the battery's lifespan while simultaneously achieving high energy density.

[0052] In some embodiments, the cathode collector has a thickness of 10 µm to 18 µm. This allows the battery to achieve a high energy density and also helps to reduce the risk of cracks in the cathode collector, thereby extending the battery's lifespan.

[0053] In some embodiments, the cathode film layer further comprises a cathode dispersion agent, which includes at least one compound from the group consisting of polyethylene glycol octylphenyl ether, polyvinylpyrrolidone, and sodium carboxymethylcellulose. The aforementioned cathode dispersion agent exhibits excellent flexibility and elasticity, enabling it to dissipate stresses to which the active cathode material is subjected during compaction. The selection of this cathode dispersion agent facilitates the achievement of a high compaction density within the cathode film layer, thereby increasing the energy density of the battery.

[0054] In some embodiments, the mass fraction of the cathode dispersion medium relative to the cathode film layer is 0.3% to 5%. This configuration contributes to the battery achieving a high energy density.

[0055] In some embodiments, the secondary battery further comprises an electrolyte solution comprising an electrolyte salt and a solvent; wherein the solvent comprises at least one compound from the group consisting of ethylidene carbonate, propylidene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylenepropyl carbonate, ethylenepropyl carbonate, butylidene carbonate, ethylidene fluorocarbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone;wherein the electrolyte salt comprises at least one compound from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate and lithium tetrafluoro(oxalato)phosphate.

[0056] In some embodiments, the electrolyte solution further comprises an additive, wherein the additive includes at least one compound from the group consisting of barium sulfate, poly(trifluoroethyl methacrylate), bicyclosulfate, tricyclosulfate, tris(trimethylsilyl) phosphate, and vinylene carbonate. The aforementioned additives undergo electrochemical reduction reactions on the surface of the anode foil prior to the solvent molecules in the electrolyte solution, forming a dense, stable SEI film. This facilitates the suppression of lithium dendrite growth and improves the battery's safety performance.

[0057] In some embodiments, the mass fraction of the additive in the electrolyte solution is 1% to 10%. This facilitates the formation of a suitable thickness of SEI film on the electrode surface. On the one hand, this suppresses the growth of lithium dendrites and improves the battery's safety performance. On the other hand, it helps to achieve a balance between the lithium-ion transfer resistance within the anode foil and the battery's fast-charging capability.

[0058] In some embodiments, the electrical conductivity of the electrolyte solution ranges from 10 mS / cm to 18.5 mS / cm. This facilitates a reduction in the battery's internal resistance and thereby reduces energy losses caused by resistance during charging and discharging cycles.

[0059] A second aspect of the present disclosure further provides a power-consuming device comprising a secondary battery as described in the first aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWING Fig. Figure 1 shows a schematic diagram of a secondary battery in an embodiment of the present disclosure; Fig. Figure 2 shows an exploded view of a secondary battery in an embodiment of the present disclosure according to Fig. 1; Fig. Figure 3 shows a schematic diagram of a battery module in an embodiment of the present disclosure; Fig. Figure 4 shows a schematic diagram of a battery pack in an embodiment of the present disclosure; Fig. Figure 5 shows an exploded view of a battery pack in an embodiment of the present disclosure according to Fig. 4; Fig.Figure 6 shows a schematic diagram of a power-consuming device in an embodiment of the present disclosure which uses a secondary battery as a power source; Fig. Figure 7 shows a scanning electron microscope (SEM) image of the separating film in a first embodiment of the present disclosure. Reference symbol list 1 battery pack 2 Upper Case 3 Lower Case 4 battery modules 5 battery cells 51 Housing body 52 Electrode component 53 Cover plate DETAILED DESCRIPTION

[0060] In the following, embodiments of the secondary battery and the power-consuming device of the present disclosure are described in detail with reference to the accompanying drawings. However, there will be instances where an unnecessarily detailed description is omitted. For example, detailed descriptions of things that are already well known and repeated descriptions of the same structure are omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding by the person skilled in the art. Furthermore, the accompanying drawings and the following description serve to enable the person skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the present disclosure.

[0061] The "range" disclosed here is defined in terms of a lower bound and an upper bound, with a particular range being defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60-120 and 80-110 is specified for a particular parameter, a range of 60-110 and 80-120 is also to be expected. Furthermore, if the minimum values ​​1 and 2 and the maximum values ​​3, 4, and 5 are specified, the following ranges can be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.Unless otherwise specified, in this disclosure, the range of values ​​"ab" denotes any combination of real numbers between a and b, where both a and b are real numbers. For example, the range of values ​​"0-5" means that all real numbers between 0 and 5 are listed here, and "0-5" is simply a shorthand representation of the combination of these values. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to stating that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0062] Unless expressly stated otherwise, all embodiments and optional embodiments of the present disclosure may be combined with one another.

[0063] Unless expressly stated otherwise, all technical features of this disclosure, as well as optional technical features, may be combined.

[0064] Unless expressly stated otherwise, all steps of this disclosure may be carried out sequentially or randomly, preferably sequentially. For example, the process includes steps (a) and (b), which means that the process may include steps (a) and (b) being carried out one after the other, or that it may include steps (b) and (a) being carried out one after the other. The statement that the process may also include step (c) means, for example, that step (c) may be added to the process in any order; for example, the process may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b).

[0065] Unless otherwise stated, the terms “comprehensive” and “inclusive” in this disclosure refer to an open list and can also be interpreted as a closed list. For example, “comprehensive” and “inclusive” may mean that the list may also contain or include components that are not expressly listed, or that it contains or includes only the listed components.

[0066] In recent years, secondary batteries have found widespread use in energy storage systems such as hydropower, thermal, wind and solar power plants, as well as in numerous fields including power tools, electric bicycles, electric motorcycles, electric vehicles and aerospace.

[0067] With the significant advancements in secondary batteries, practical applications now place higher demands on the energy density and safety performance of the secondary battery.

[0068] In related technologies, increasing the energy density of batteries is often achieved by increasing the density of the film layer. However, this approach has a significant drawback: while increasing the density, it also increases heat dissipation within the battery, thus compromising its safety performance. For example, the separating film is typically made of macromolecular polymers such as polyethylene (PE) or polypropylene (PP). These polymeric substances consist of molecules formed from long, chain-like molecular structures. At ambient temperatures, these molecular chains are in a relatively stable state and are held together by intermolecular forces that maintain the shape of the separating film. As the temperature rises, the molecules gain additional energy, intensifying the thermal motion within the molecular chain.This increases the distance between the molecular chains and promotes a disordered arrangement. Such movements of the molecular chains and changes in arrangement cause macroscopic dimensional changes in the separator film, which manifest as thermal shrinkage. The thermal shrinkage of the separator film can lead to an overlap of the cathode and anode foils, thereby impairing the battery's safety performance. Therefore, striking a balance between battery energy density and safety performance has become a pressing technical challenge.

[0069] To solve the technical problems described above, the present disclosure provides a secondary battery and a power-consuming device. This secondary battery achieves a balance between energy density and safety performance.

[0070] A first aspect of the present disclosure provides a secondary battery comprising a cathode foil, an anode foil and a separating film, wherein the cathode foil comprises a cathode collector and a cathode film layer arranged on the surface of at least one side of the cathode collector, wherein the density of the cathode film layer is 2.0 g / cm³ 3 up to 3.0 g / cm³ 3 is; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector, wherein the density of the anode film layer is 1.4 g / cm³ 3 up to 1.85 g / cm³ 3 is; wherein the separating film comprises a base film having a thickness of 4 µm to 12 µm.

[0071] In the present disclosure, the control of the pressure density of the cathode film layer between 2.0 g / cm² is facilitated. 3 and 3.0 g / cm² 3 and the anode film layer between 1.4 g / cm²3 and 1.85 g / cm² 3 achieving a high energy density of the battery.

[0072] While the aforementioned compression densities facilitate the compact arrangement of the electrode material particles and thus improve the battery's energy density, they can simultaneously hinder electrolyte permeation and increase the battery's internal resistance. This can lead to excessive heat generation during discharge and impair the battery's safety performance.

[0073] The present disclosure utilizes a base film with a thickness of 4 µm to 12 µm. This mitigates the adverse effects on the battery's safety performance caused by a base film that is too thin (less than 4 µm) and simultaneously reduces the adverse effects on the battery's energy density caused by a base film that is too thick (more than 12 µm). This configuration improves the battery's safety performance while ensuring high energy density. In particular, within the aforementioned thickness range, the base film can maintain its structural stability at elevated temperatures, thus effectively reducing the risk of a short circuit between the positive and negative electrodes. Specifically, in the event of thermal runaway, the stable structure of the base film can suppress the occurrence of side reactions through physical insulation.This lowers the peak temperature of the battery's thermal runaway, reduces the risk of thermal spread, and improves the battery's safety performance. Furthermore, the base film, within the aforementioned thickness range, helps to mitigate adverse effects on the battery's energy density, thus facilitating the maintenance of a high energy density. In addition, the base film features nanopores with an average pore size of 10 nm to 300 nm. By using a base film with nanopores exhibiting an average pore size within this range, an improved lithium-ion migration rate is enabled while simultaneously suppressing the growth of lithium dendrites, further enhancing the battery's safety performance.

[0074] In the present disclosure, "density" refers to the mass per unit volume of the active material (the active cathode material, the negative active material) after compaction under specific pressure conditions. Within the battery system, it primarily characterizes the compactness of the cathode film layer and the anode film layer and reflects the amount of active material charged per unit volume of the electrode film layer.

[0075] The compression density in the present disclosure can be tested using methods known in this field. The electrode foils to be tested (cathode foil, anode foil) can be manufactured electrode foils or electrode foils obtained by dismantling batteries. For example, if a cathode foil is obtained from a dismantled battery, the cathode foil is formed into a circular disk with an area of ​​1540.25 mm². 2The disc is cut. Its mass is weighed as m1. Using a micrometer, the thickness of the disc is measured multiple times at various points, and the average value is recorded as d1. The cathode film layer is then removed from one side of the disc. The mass of this disc is weighed as m2. The thickness of this disc is measured multiple times at various points using a micrometer, and the average value is recorded as d2. The value (m1 - m2) / (d1 - d2) is assumed to be the compression density of the cathode film layer.

[0076] In the present disclosure, the density of the cathode film layer is 2 g / cm³. 3 up to 3 g / cm² 3 For example, the density of the cathode film layer can be 2 g / cm³. 3 , 2.1 g / cm³ 3 , 2.2 g / cm³ 3 , 2.3 g / cm³ 3 , 2.4 g / cm³ 3 , 2.5 g / cm³ 3 , 2.60 g / cm³ 3 , 2.7 g / cm³ 3 , 2.8 g / cm³ 3 , 2.9 g / cm³3 , 3 g / cm 3 or a value within the range formed by any two of these values. Optionally, the density of the cathode film layer is 2.3 g / cm³. 3 up to 2.5 g / cm³ 3 .

[0077] In the present disclosure, the compression density of the anode film layer is 1.4 g / cm³. 3 up to 1.85 g / cm³ 3 For example, the compression density of the anode film layer can be 1.4 g / cm³. 3 , 1.5 g / cm³ 3 , 1.55 g / cm³ 3 , 1.60 g / cm³ 3 , 1.62 g / cm³ 3 , 1.64 g / cm³ 3 , 1.65 g / cm³ 3 , 1.85 g / cm³ 3 or be a value within the range formed by any two of these values.

[0078] In the present disclosure, the thickness of the base film can be measured with a micrometer screw or a tenth-of-a-micrometer screw. For example, the thickness can be measured multiple times at different locations on the base film using a micrometer screw, and the average value is taken as the thickness of the base film.

[0079] In the present disclosure, the base film has a thickness of 4 µm to 12 µm. For example, the thickness of the base film is 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, or a value within the range formed by any two of these values. Optionally, the base film has a thickness of 5 µm to 9 µm.

[0080] The average pore size in the present disclosure can be verified using methods known in this field. The separator film to be tested can be a manufactured separator film or a separator film obtained by dismantling a battery. For example, if a separator film (base film) is obtained from a dismantled battery, a pore size tester (model: PMI Porometer) can be used to test the average pore size of the base film with reference to GB / T 21650.2-2008.

[0081] For example, the average pore size of the nanopores can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, or a value within the range formed by any two of these values. The term "secondary battery" mentioned in this description refers to a battery cell, a battery module, or a battery pack. These are explained in detail below. Unless otherwise specified, the term "battery" in this disclosure refers to a secondary battery.

[0082] A typical secondary battery comprises a cathode foil, an anode foil, an electrolyte, and a separating film. During the charging and discharging process, lithium ions migrate back and forth between the cathode foil and the anode foil, being stored and removed. The electrolyte acts as an ion conductor between the cathode foil and the anode foil. The separating film between the cathode foil and the anode foil primarily prevents a short circuit between the positive and negative electrodes while allowing the passage of ions. Release film

[0083] The present disclosure does not impose any specific restrictions regarding the type of separating film, and any known separating film with a porous structure and good chemical and mechanical stability can be selected.

[0084] In some embodiments, the separating film material can be at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separating film can be a single-layer film or a multi-layer composite film without any particular restriction. If the insulating film is a multi-layer composite film, the materials of the layers can be the same or different without any particular restriction.

[0085] In some embodiments, the base film comprises at least one of a polyethylene base film, a polypropylene base film, a polyethylene-polypropylene composite base film, a polyethylene nonwoven base film, a polypropylene nonwoven base film, a polypropylene-polypropylene composite base film, a polyimide base film, a polyimide nonwoven base film, a polytetrafluoroethylene base film, a polytetrafluoroethylene nonwoven base film, a polyvinyl chloride base film and a polyvinyl chloride nonwoven base film.

[0086] In some embodiments, the base film has a porosity of 20% to 70%. By using a base film with a porosity within the aforementioned range, an improved lithium-ion migration rate is enabled while simultaneously suppressing the growth of lithium dendrites, further enhancing the battery's safety performance. For example, the base film porosity can be 20%, 30%, 40%, 50%, 60%, 70%, or a value within the range formed by any two of these values. Optionally, the base film has a porosity of 35% to 42%.

[0087] In some embodiments, the separating film further comprises a coating arranged on at least one side of the base film, wherein the coating includes heat-resistant particles woven into a porous structure. Compared to coatings without such a porous structure, the heat-resistant particles in this embodiment are woven into a porous structure, which allows for less obstruction of ion transport by the coating, thereby improving ion transport efficiency. Furthermore, the coating comprises heat-resistant particles that exhibit only minimal volume changes under temperature fluctuations. Applying this heat-resistant, particle-containing coating to the surface of the base film suppresses the thermal shrinkage rate of the base film. This reduces the risk of a short circuit between the positive and negative electrodes and thus improves the battery's safety performance.

[0088] In some embodiments, the coating applied to at least one side of the base film has a thickness of 0.011 µm to 3 µm. Selecting a coating with a thickness within the aforementioned range makes it easier for the battery to achieve a high energy density and allows the coating to more effectively suppress the thermal shrinkage rate of the base film, thereby further improving the battery's safety performance. For example, the thickness of the coating is 0.011 µm, 0.02 µm, 0.03 µm, 0.04 µm, 0.05 µm, 0.06 µm, 0.07 µm, 0.08 µm, 0.09 µm, 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm or a value within the range formed by any two of these values.

[0089] In some embodiments, the heat-resistant particles have an average particle size of 5 nm to 185 nm. These heat-resistant particles can form a coating with a stable support network structure. This structure not only supports the base film but also suppresses thermal shrinkage of the base film, thereby improving the battery's safety performance. For example, the average particle size of the heat-resistant particles is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 185 nm, or a value within the range formed by any two of these values.

[0090] In some embodiments, the particle surface density of the heat-resistant particles is 0.5 mg / 1540.25 cm². 2up to 2.5 mg / 1540.25 cm 2 Controlling the particle area density within the aforementioned range facilitates achieving a high energy density in the battery and allows the heat-resistant particles to effectively suppress thermal shrinkage of the base film, thereby improving the battery's safety performance. For example, the particle area density of the heat-resistant particles is 0.5 mg / 1540.25 cm². 2 , 0.6 mg / 1540.25 cm 2 , 0.7 mg / 1540.25 cm 2 , 0.8 mg / 1540.25 cm 2 , 0.9 mg / 1540.25 cm 2 , 1 mg / 1540.25 cm 2 , 1.1 mg / 1540.25 cm 2 , 1.2 mg / 1540.25 cm 2 , 1.25 mg / 1540.25 cm 2 , 1.3 mg / 1540.25 cm 2 , 1.4 mg / 1540.25 cm 2 , 1.5 mg / 1540.25 cm 2 , 1.6 mg / 1540.25 cm 2 , 1.7 mg / 1540.25 cm 2 , 1.8 mg / 1540.25 cm 2 , 1.85 mg / 1540.25 cm 2or a value within the range formed by any two of these values. Optionally, the particle surface density of the heat-resistant particles is 1.25 mg / 1540.25 cm³. 2 up to 1.85 mg / 1540.25 cm 2 amounts.

[0091] In some embodiments, the heat-resistant particles comprise first heat-resistant particles distributed along the thickness direction of the base film. In this implementation, the first heat-resistant particles are distributed on the surface of the base film and can directly suppress thermal shrinkage of the base film. This further improves the battery's safety performance while maintaining its energy density.

[0092] In some embodiments, the heat-resistant particles comprise first and second heat-resistant particles; the first heat-resistant particles are distributed across the surface of the base film, and the second heat-resistant particles are stacked on the side of the first heat-resistant particles facing away from the base film. In this implementation, the stacking arrangement of the first and second heat-resistant particles along the thickness direction of the base film facilitates the formation of a thicker coating. This thicker coating acts as a more effective physical barrier, reducing chemical erosion of the base film by the electrolyte solution while simultaneously mitigating friction from the electrode foils (cathode foil, anode foil). This further improves the battery's safety performance.

[0093] In some embodiments, the heat-resistant particles comprise inorganic particles and bonding particles. In this implementation, the bonding particles act as bridges, firmly connecting the inorganic particles. This creates a stable, integrated structure for the inorganic particles, thereby improving the mechanical strength and stability of the coating. Consequently, the coating better suppresses the thermal shrinkage of the base film.

[0094] In some embodiments, the first glass transition temperature of the binding particles is 30°C to 75°C; and / or wherein the second glass transition temperature of the binding particles is -10°C to 25°C.

[0095] In some embodiments, the binding particles comprise one or more of the following materials: polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane, and polystyrene.

[0096] In some embodiments, the heat-resistant particles comprise inorganic particles and a bonding layer applied to at least a portion of the surface of the inorganic particles. In this implementation, the bonding layer is applied to the surface of the inorganic particles, thereby enabling increased bonding strength between the inorganic particles and the base film. This reduces the risk of inorganic particle detachment and contributes to improved safety performance and battery lifespan.

[0097] In some embodiments, the first glass transition temperature of the bonding layer is 30°C to 75°C; and / or wherein the second glass transition temperature of the bonding layer is -10°C to 25°C.

[0098] In some embodiments, the bonding layer comprises one or more compounds from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyurethane and polystyrene.

[0099] In some embodiments, the inorganic particles comprise at least one compound from the group consisting of aluminum trioxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, boehmite, magnesium oxide, zinc oxide, barium sulfate, magnesium nitride, and barium titanate. These substances exhibit only small volume changes under temperature fluctuations. Their use as inorganic particles further suppresses the thermal shrinkage of the base film and thereby improves the battery's safety performance.

[0100] In some embodiments, the mass fraction of inorganic particles in the coating ranges from 5% to 30%. Controlling the mass fraction of inorganic particles within the aforementioned range facilitates the formation of a heat-resistant skeletal structure within the coating, effectively suppressing thermal shrinkage of the coating, improving battery safety performance, and simultaneously reducing the risk of inorganic particle detachment. For example, the mass fraction of inorganic particles may be 5%, 10%, 15%, 20%, 25%, 30%, or a value within the range formed by any two of these values.

[0101] The mass fraction of inorganic particles in the present disclosure can be tested using methods known in this field. The separating film to be tested can be a manufactured separating film or a separating film obtained by dismantling a battery. For example, if it is a separating film obtained by dismantling a battery, the coating is separated from the base film and collected, and then the mass of the coating is measured in m³. The bonding particles or the bonding layer are dissolved with a suitable solvent, after which the inorganic particles are filtered out and their mass m⁴ is measured. The mass fraction of the inorganic particles is then calculated as m⁴ / m³. Anode foil

[0102] A first aspect of the present disclosure provides a secondary battery comprising an anode foil, wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector, wherein the anode film layer comprises a first film layer and a second film layer arranged between the first film layer and the anode collector, wherein the first film layer comprises a first active anode material comprising a first graphite material, wherein the I D / I G -ratio of the first graphite material is 0.4 to 0.9; wherein the second film layer comprises a second active anode material which comprises a second graphite material, wherein the I D / I G -ratio of the second graphite material is 0.05 to 0.2; where I D for the intensity of the D-peak of the Raman spectrum at 1350±50 cm -1and IG for the intensity of the G-peak of the Raman spectrum at 1580±50 cm -1 stands.

[0103] The I D / I G The ratio of the first graphite material used in the present disclosure is 0.4 to 0.9, indicating the presence of numerous surface defects on the first graphite material. These defects serve as additional active sites for lithium ion intercalation. The arrangement of this first graphite material with numerous surface defects in the outer layer (first film layer) of the anode foil facilitates an increased probability of contact between these additional active sites and the electrolyte solution, thereby improving the fast-charging capability of the battery.

[0104] Based on this, a second graphite material with an I is used for the inner layer (second film layer) of the anode foil. D / I GA ratio of 0.05 to 0.2 is used. This second graphite material has fewer surface defects and a relatively intact structure, which helps to reduce the irreversible loss of lithium ions and thus extend the battery's lifespan.

[0105] The morphology of the anode foil in the present disclosure can be examined using methods known in this field. The anode foils to be examined can be manufactured anode foils or anode foils obtained by dismantling batteries. The test process is described below using the latter example. In particular, the anode foil is obtained from a dismantled battery. The anode foil is placed in a sample holder and locked and secured there. An argon-ion cross-section polisher (e.g., the IB-09010 CP model from JEOL Ltd., Japan) is activated to extract a cross-section of the anode foil. Subsequently, a scanning electron microscope (HR-TEM Talos F200) is used to acquire SEM images of the cross-section of the anode foil.The cross-sectional SEM images show that the anode foil comprises an anode collector, a second film layer arranged on the surface of the anode collector, and a first film layer arranged on the surface of the second film layer.

[0106] The I D / I G The values ​​of graphite materials (first graphite material, second graphite material) in the present disclosure can be tested using methods known in this field. The graphite material to be tested can be a manufactured graphite material or a graphite material obtained by dismantling a battery. The test process is described below using the latter example. In particular, the anode foil is obtained from a dismantled battery. The first film layer is scraped off with a scraper, dissolved in a suitable solvent, and then filtered to obtain the first graphite material, whose I D / I G-ratios are tested. The second film layer is scraped off with a scraper, dissolved in a suitable solvent, and then filtered to obtain the second graphite material, whose I D / I G The ratios are tested. It should be noted that a distinct interface may or may not exist between the first and second film layers. To minimize sampling error, the sampling area for the second film layer extends 2.5 µm from the surface of the anode film layer facing the current collector towards the anode film layer; the sampling area for the second film layer extends 2.5 µm from the surface of the anode film layer facing away from the current collector towards the anode film layer.

[0107] The test conditions are as follows: excitation wavelength 532 nm, 600 lines / mm grating, 50× objective lens, 10-second integration time, 3 cumulative measurements, surface scan. This yields D- and G-peak intensities at 100 points. D / I G The ratio is calculated for these 100 points, where the maximum and minimum 30 I D / I G -ratioes are excluded. The average of the remaining 40 points forms the I. D / I G -ratio of the material. The Horiba Lab RAM HR800 Raman spectrometer can be used as a test instrument.

[0108] In the present disclosure, the I D / I G The ratio of the first graphite material is 0.4 to 0.9. For example, the I D / I G-Ratio of the first graphite material 0.4, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9 or a value within the range formed by any two values, is, however, not limited to this.

[0109] In the present disclosure, the I D / I G The ratio of the second graphite material is 0.05 to 0.2. For example, the I D / I G -Ratio of the second graphite material 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2 or a value within the range formed by any two values, is, however, not limited to this.

[0110] For example, the anode collector has two surfaces that are opposite each other in its own thickness direction, with the anode film layer being arranged on one or two of the two opposite surfaces of the anode collector.

[0111] In some embodiments, the volume-averaged particle size of the first graphite material is 9.2 µm to 15.5 µm. This facilitates the formation of numerous porous channel structures between the particles of the first graphite material, improves the lithium-ion and electron transport properties within the first film layer, and thereby enhances the kinetic performance of the secondary battery. For example, the volume-averaged particle size Dv50 of the first graphite material can be 9.2 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, 15.5 µm, or a value within the range formed by any two values, but is not limited to these.

[0112] In some embodiments, the volume-averaged particle size Dv50 of the second graphite material is 16.3 µm to 25.5 µm. This facilitates increased packing density within the second film layer, thereby improving the energy density of the secondary battery. Furthermore, it facilitates the formation of numerous porous channel structures between the particles of the second graphite material, improving the lithium-ion and electron transport properties within the anode film layer and thus enhancing the kinetic performance of the secondary battery. For example, the volume-averaged particle size Dv50 of the second graphite material can be 16.3 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm, 22 µm, 23 µm, 24 µm, 25.5 µm, or a value within the range formed by any two values, but is not limited to these values.

[0113] In the present disclosure, the volume-distributed particle size Dv50 of the material denotes the particle size corresponding to the cumulative volume distribution percentage of the material of 50%. This can be measured using instruments and methods known in this field. For example, the measurement according to GB / T 19077-2016 can be carried out using a laser particle size analyzer. The testing device can be the Mastersizer 3000 laser particle size analyzer from Malvern Instruments GmbH.

[0114] In some embodiments, the BET-specific surface area of ​​the first graphite material is 0.3 m². 2 / g up to 3 m 2 / g. If the BET-specific surface area of ​​the first graphite material falls within the range mentioned above, the surface of the first graphite material can offer more pathways for the insertion and removal of lithium ions. During fast charging, lithium ions can traverse these pathways more quickly to be incorporated into the first graphite material, thereby reducing both the transport distance and the resistance of the lithium ions, thus improving the battery's fast-charging capability. For example, the BET-specific surface area of ​​the first graphite material is 0.3 m². 2 / g, 0.4 m 2 / g, 0.5 m 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1 m 2 / g, 1.5 m 2 / g, 2 m 2 / g, 2.5 m 2 / g, 3 m 2 / g or a value within the range formed by any two values, is not limited to

[0115] In some embodiments, the BET-specific surface area of ​​the second graphite material is 0.5 m². 2 / g up to 5 m 2 / g. If the BET-specific surface area of ​​the second graphite material falls within the range mentioned above, the surface of the second graphite material can offer more pathways for the insertion and removal of lithium ions. During fast charging, lithium ions can traverse these pathways more quickly to be incorporated into the second graphite material, thereby reducing both the transport distance and the resistance of the lithium ions, thus improving the battery's fast-charging capability. For example, the BET-specific surface area of ​​the second graphite material is 0.5 m². 2 / g, 0.6 m 2 / g, 0.7 m 2 / g, 0.8 m 2 / g, 0.9 m 2 / g, 1 m 2 / g, 1.5 m 2 / g, 2 m 2 / g, 2.5 m 2 / g, 3 m 2 / g, 3.5 m 2 / g, 4 m 2 / g, 4.5 m2 / g, 5 m 2 / g or a value within the range formed by any two values, is not limited to that.

[0116] In the present disclosure, the BET-specific surface area of ​​materials (second graphite material, first graphite material, first active cathode material) has a meaning known in the art and can be measured using instruments and methods known in this field. For example, the test can be carried out according to GB / T 19587-2017 using the method for specific surface area analysis by nitrogen adsorption, whereby the BET-specific surface area is determined using the BET method (Brunauer Emmett Teller). The testing instrument can be the Tri-Star 3020 Specific Surface Area and Pore Size Analyzer manufactured by Micromeritics, USA.

[0117] In some embodiments, the bulk density of the first graphite material is 0.7 g / cm³.3 up to 1.6 g / cm³ 3 The bulk density of the first graphite material within the aforementioned range facilitates the formation of numerous porous structures within the first film layer and ensures that the battery exhibits superior fast-charging capability. For example, the bulk density of the first graphite material is 0.7 g / cm³. 3 , 0.8 g / cm³ 3 , 0.9 g / cm³ 3 , 1 g / cm 3 , 1.1 g / cm³ 3 , 1.2 g / cm³ 3 , 1.3 g / cm³ 3 , 1.4 g / cm³ 3 , 1.5 g / cm³ 3 , 1.6 g / cm³ 3 or a value within the range formed by any two values, but is not limited to that.

[0118] In some embodiments, the bulk density of the second graphite material is 0.8 g / cm³. 3 up to 1.5 g / cm³ 3The bulk density of the second graphite material lies within the aforementioned range; therefore, the second graphite material can be densely packed in the second film layer, allowing larger quantities of the second graphite material (active ingredient) to be accommodated in the second film layer to increase the battery's energy density. For example, the bulk density of the second graphite material is 0.8 g / cm³. 3 , 0.9 g / cm³ 3 , 1 g / cm 3 , 1.1 g / cm³ 3 , 1.2 g / cm³ 3 , 1.3 g / cm³ 3 , 1.4 g / cm³ 3 , 1.5 g / cm³ 3 or a value within the range formed by any two values, but is not limited to that.

[0119] In the present disclosure, the bulk density of materials (second graphite material, first graphite material, first active cathode material) has a meaning known in the art and can be measured using instruments and methods known in this field. For example, the measurement according to GB / T 5162-2006 can be carried out using a powder bulk density meter. The test instrument can be the Dandong Baite BT-301 model with the following parameters: shaking frequency 250 ± 15 strokes / minute, amplitude 3 ± 0.2 mm, number of shakes 5000 strokes, measuring cylinder 25 mL.

[0120] In some embodiments, the first active anode material further comprises an anode coating layer distributed on the surface of the first graphite material, which includes amorphous carbon. The structure of amorphous carbon is relatively loose and exhibits numerous porous structures. These pores provide additional diffusion pathways for lithium ions and shorten their diffusion path within the electrode material. By arranging amorphous carbon on the surface of the first graphite material, lithium ions can penetrate the anode coating layer more quickly to reach the interior of the first graphite material, thereby improving the fast-charging capability of the battery.

[0121] In the present disclosure, TEM can be used to characterize the anode coating layer on the surface of the first graphite material. SEM is used to acquire data on the microstructural morphology of the first active anode material. TEM reveals that the first graphite material exhibits a periodically repeating lattice structure. The absence of a regular lattice structure on the surface of the first graphite material indicates the presence of amorphous carbon on its surface.

[0122] In some embodiments, the anode coating layer has a thickness of 10 nm to 100 nm. Maintaining this thickness range for the anode coating layer makes it easier for the secondary battery to achieve a balance between fast-charging capability and energy density. For example, the thickness of the anode coating layer may be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or a value within the range formed by any two values, but is not limited to these values.

[0123] In the present disclosure, the thickness of the anode coating layer can be characterized using scanning electron microscopy (SEM) in combination with focused ion beam (FIB) techniques. The sample (first active anode material) is mounted on a sample stage, and a shallow cross-section is cut into the sample surface using FIB. The cross-section is then imaged with SEM, and the thickness of the anode coating layer is determined by measuring its width within the image.

[0124] In some embodiments, the second film layer further comprises a first graphite material. The second graphite material can reduce the irreversible loss of active lithium ions during multiple charge-discharge cycles, thereby reducing the rate of capacity loss in the battery and extending its lifespan. The first graphite material can improve the battery's fast-charging capability. In this embodiment, the arrangement of both the second and first graphite materials within the second film layer facilitates the improvement of the battery's fast-charging capability.

[0125] In the present disclosure, the second graphite material and the first graphite material incorporated into the second film layer can be tested using methods known in this field. The anode foils to be tested can be manufactured anode foils or anode foils obtained by dismantling batteries. In particular, the anode foil is placed in a sample holder and locked and secured there. An argon-ion cross-section polisher (e.g., the IB-09010 CP model from JEOL Ltd., Japan) is activated to extract a cross-section of the anode foil. Subsequently, a scanning electron microscope (HR-TEM Talos F200) is used to acquire SEM images of the cross-section of the anode foil. The cross-sectional SEM images show that the anode foil comprises an anode collector, a second film layer arranged on the surface of the anode collector, and a first film layer arranged on the surface of the second film layer.The second film layer comprises coarse-grained material and fine-grained material. The coarse-grained material is the second graphite material, and the fine-grained material is the first graphite material.

[0126] In some embodiments, the mass ratio of the second graphite material to the first graphite material in the second film layer is (3-5):(5-7). Controlling the mass ratio of the second graphite material to the first graphite material in the second film layer within the aforementioned range facilitates the simultaneous improvement of fast-charging capability and battery lifespan. For example, the mass ratio of the second graphite material to the first graphite material in the second film layer may be 5:5, 4:6, 3:7, or a value within, but not limited to, any two values ​​in the range.

[0127] In the present disclosure, the mass ratio of the second graphite material to the first graphite material in the second film layer can be tested using methods known in this field. The anode foils to be tested can be manufactured anode foils or anode foils obtained by dismantling batteries. In particular, when obtaining an anode foil from a dismantled battery, the first film layer is removed using a scraper to expose the second film layer. The second film layer is then removed using a scraper and collected. A suitable solvent is used to dissolve the second membrane layer, and a mixture of the second graphite material and the first graphite material is obtained by filtration. Using the difference in particle size between the second graphite material and the first graphite material, the two are separated.The mass of the second graphite material and the mass of the first graphite material are weighed separately, thereby determining the mass ratio of the second graphite material to the first graphite material within the second film layer.

[0128] In some embodiments, the ratio of the average thickness of the first film layer to the average thickness of the second film layer is (3-5):(5-7). Controlling the ratio of the average thickness of the first film layer to the average thickness of the second film layer within the aforementioned range facilitates the simultaneous improvement of fast-charging capability and battery lifespan. For example, the ratio of the average thickness of the first film layer to the average thickness of the second film layer may be 5:5, 4:6, 3:7, or a value within, but not limited to, the range formed by any two values.

[0129] In the present disclosure, the ratio of the average thickness of the first film layer to the average thickness of the second film layer can be verified using methods known in this field. The anode foils to be tested can be manufactured anode foils or anode foils obtained by dismantling batteries. In particular, cross-sectional SEM images of the anode foil are acquired using a scanning electron microscope (HR-TEM Talos F200). The cross-sectional SEM images clearly show that the anode foil comprises an anode collector, a second film layer on the surface of the current collector, and a first film layer on the surface of the second film layer. Subsequently, four sampling points are selected evenly spaced on the first and second film layers. Using image analysis software, the thickness of the film layers at each sampling point is accurately measured.The average thickness of the first film layer is determined by averaging the thickness values ​​of the four sampling points on the first film layer. The average thickness of the second film layer is determined in a similar manner. Finally, by calculating the ratio of the two average thicknesses, the exact ratio between the average thickness of the first film layer and the average thickness of the second film layer is determined.

[0130] In some embodiments, the first film layer further comprises a first binder. The first binder comprises at least one of the following: styrene-butadiene rubber, styrene-polybutadiene rubber, lithium polyacrylate, polyacrylate, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethyl methacrylate, and carboxymethyl chitosan. These substances exhibit high viscosity. By selecting one or more of these substances as the first binder, the risk of separation of the first film layer from the second film layer can be reduced, thereby further extending the service life of the secondary battery.

[0131] In some embodiments, the first binder comprises at least one of styrene-butadiene rubber, lithium polyacrylate, and polyacrylate.

[0132] Styrene-butadiene rubber exhibits excellent flexibility and elasticity. During charging and discharging of the electrode, it distributes the stresses to which the first active anode material is subjected during compression, enabling the first active anode material to withstand higher pressures. The selection of styrene-butadiene rubber as the first dispersion agent contributes to the first film layer achieving a high compression density, thereby increasing the battery's energy density.

[0133] Lithium polyacrylate has a high ionic conductivity, and the selection of lithium polyacrylate as the first binder improves the fast-charging capability of the battery.

[0134] Polyacrylate can increase the compression modulus of the first active anode material and reduce adverse effects on the kinetic performance of the anode foil during compression, in order to improve the fast charging capability of the battery.

[0135] In some embodiments, the second film layer further comprises a second binder. The second binder comprises at least one of the following: styrene-butadiene rubber, styrene-polybutadiene rubber, lithium polyacrylate, polyacrylate, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethyl methacrylate, and carboxymethyl chitosan. The second binder exhibits high viscosity. By selecting one or more of these substances as the second binder, the risk of separation of the second film layer from the anode collector can be reduced, thereby further extending the service life of the secondary battery.

[0136] In some embodiments, the second binder comprises at least one of styrene-butadiene rubber, lithium polyacrylate, and polyacrylate. In this embodiment, the selection of the aforementioned substances as the second binder facilitates a balance between the fast-charging capability, lifespan, and energy density of the battery.

[0137] In some embodiments, the mass fraction of the first binder in the first film layer is 0.1% to 2%. Controlling the mass fraction of the first binder in the first film layer within the aforementioned range helps, on the one hand, to prevent the first active anode material from becoming powdery and detaching, thereby extending the battery's lifetime. On the other hand, this helps the battery achieve a high energy density. For example, the mass fraction of the first binder in the first film layer is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, 2%, or a value within the range formed by any two values.

[0138] In some embodiments, the mass fraction of the second binder in the second film layer is 0.1% to 2%. Controlling the mass fraction of the second binder in the second film layer within the aforementioned range helps, on the one hand, to prevent the first active anode material from becoming powdery and detaching, thereby extending the battery's lifespan. On the other hand, this contributes to the battery achieving a high energy density. For example, the mass fraction of the second binder in the second film layer is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, 2%, or a value within the range formed by any two values.

[0139] In some embodiments, the first film layer further comprises a first dispersion agent, wherein the first dispersion agent comprises at least one polymer selected from lithium carboxymethylcellulose and sodium carboxymethylcellulose.

[0140] The substances mentioned above have a high ionic conductivity, and selecting these substances as the first dispersion agent improves the fast charging capability of the battery.

[0141] In some embodiments, the second film layer further comprises a second dispersion agent, wherein the second dispersion agent includes at least one of lithium carboxymethylcellulose and sodium carboxymethylcellulose. The aforementioned substances exhibit high ionic conductivity, and the selection of these substances as the second dispersion agent improves the fast-charging capability of the battery.

[0142] In some embodiments, the first dispersion agent comprises lithium carboxymethylcellulose. Lithium carboxymethylcellulose contains lithium ions, which compensates for the loss of active lithium ions during the initial charge due to the formation of an SEI film, consequently improving the initial charge efficiency of the battery.

[0143] In some embodiments, the second dispersion agent comprises lithium carboxymethylcellulose. Lithium carboxymethylcellulose contains lithium ions, which compensates for the loss of active lithium ions during the initial charge due to the formation of an SEI film, consequently improving the initial charge efficiency of the battery.

[0144] In some embodiments, the mass fraction of the first dispersion agent in the first film layer is 0.3% to 1.5%. By controlling the mass fraction of the first dispersion agent in the first film layer within the aforementioned range, it is made easier for the battery to achieve a high energy density. For example, the mass fraction of the first dispersion agent is 0.3%, 0.5%, 1%, 1.5%, or a value within the range formed by any two values.

[0145] In some embodiments, the mass fraction of the second dispersion agent in the second film layer is 0.3% to 1.5%. By controlling the mass fraction of the second dispersion agent in the second film layer within the aforementioned range, it is easier for the battery to achieve a high energy density. For example, the mass fraction of the second dispersion agent is 0.3%, 0.5%, 1%, 1.5%, or a value within the range formed by any two values.

[0146] In some embodiments, the first film layer further comprises a first conductive agent, wherein the first conductive agent includes at least one of superconducting carbon, carbon black, boron carbon black, carbon dots, graphene, carbon nanofibers, carbon nanotubes, and conductive carbon black. These substances exhibit excellent electrical conductivity. The use of such substances as the first conductive agent facilitates further improvement of the battery's fast-charging capability. Optionally, the first conductive agent comprises carbon nanotubes and conductive carbon black. The selection of such substances as the first conductive agent facilitates further improvement of the battery's fast-charging capability.

[0147] In some embodiments, the second film layer further comprises a second conductive material, wherein the second conductive material includes at least one of superconducting carbon, carbon black, boron carbon black, carbon dots, graphene, carbon nanofibers, carbon nanotubes, and conductive carbon black. These substances exhibit excellent electrical conductivity. The use of such substances as a second conductive material facilitates further improvement of the battery's fast-charging capability. Optionally, the first conductive material comprises carbon nanotubes and conductive carbon black.

[0148] In some embodiments, the mass fraction of the first conductive agent in the first film layer is 0.1% to 2%. By controlling the mass fraction of the first conductive agent in the first film layer within the aforementioned range, the overall conductivity of the first film layer is improved, thereby further enhancing the fast-charging capability of the secondary battery. For example, the mass fraction of the first conductive agent in the first film layer is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, or a value within the range formed by any two values.

[0149] In some embodiments, the mass fraction of the second conductive agent in the second film layer is 0.1% to 2%. By controlling the mass fraction of the second conductive agent in the second film layer within the aforementioned range, the overall conductivity of the second film layer is improved, thereby further enhancing the fast-charging capability of the secondary battery. For example, the mass fraction of the second conductive agent in the second film layer is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, or a value within the range formed by any two values.

[0150] In some embodiments, the thickness of the anode film layer arranged on one side of the anode collector is 40 µm to 75 µm; controlling the thickness of the anode film layer within the aforementioned range allows the anode film layer to achieve both high capacity and good lithium-ion and electron transport properties, enabling the secondary battery to achieve a balance between high energy density and fast-charging capability. For example, the thickness of the anode film layer can be 40 µm, 45 µm, 50 µm, 55 µm, 60 µm, 65 µm, 70 µm, 75 µm, or a value within the range formed by any two of these values.

[0151] In some embodiments, the coating weight of the anode film layer arranged on one side of the anode collector is 80 mg / 1540.25 mm². 2 up to 170 mg / 1540.25 mm 2Controlling the coating weight of the anode film layer within the aforementioned range allows for an increase in the number of lithium ions released per unit area of ​​the anode film layer, thereby improving the battery's energy density. For example, the coating weight of the anode film layer is 80 mg / 1540.25 mm². 2 , 90 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 , 160 mg / 1540.25 mm 2 , 170 mg / 1540.25 mm 2 or a value within the range formed by any two values.

[0152] The coating weight of the anode film layer in the present disclosure can be tested using methods known in this field. The anode foils to be tested can be manufactured anode foils or anode foils obtained by dismantling batteries. In particular, if an anode foil is obtained from a dismantled battery, the anode foil is formed into a circular disk with an area of ​​1540.25 mm². 2 The circular disk is cut. The mass of the resulting disc is weighed as m5. Then, the anode film layer is removed from one side of the circular disk, and the mass of the disk is weighed again as m6. The difference between m5 and m6 is taken as the coating weight of the anode film layer.

[0153] In some embodiments, the anode collector has a thickness of 4 µm to 8 µm. This thickness range of the anode collector allows the battery to achieve a high energy density and also helps to reduce the risk of cracks in the anode collector, thereby extending the battery's lifespan. For example, the thickness of the anode collector may 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 value within the range formed by any two of these values.

[0154] In some embodiments, the anode collector can be a metal foil or a composite collector. For example, a copper foil can be used as the metal foil. The composite collector can comprise a base layer of polymeric material and a metal layer formed on at least one surface of the polymeric base layer. The composite collector can be formed by depositing metallic material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0155] In some embodiments, the anode film layer optionally includes further additives, such as thickening agents (e.g. sodium carboxymethylcellulose (CMC-Na)), etc.

[0156] In some embodiments, the anode foil can be produced as follows: Dispersing the components described above for the production of the anode foil, such as the active anode material, the conductive agent, the binder and other components, in a solvent (e.g. deionized water) to form an anode slurry; applying the anode slurry to the anode collector and obtaining the anode foil after drying, cold pressing and other processes. cathode foil

[0157] In some embodiments, the cathode foil comprises a cathode collector and a cathode film layer arranged on at least one surface of the cathode collector. The cathode film layer comprises an active cathode material, which in turn comprises a first active cathode material, wherein the first active cathode material comprises a lithium-containing phosphate with an olivine structure. The lithium-containing phosphate with an olivine structure exhibits a stable three-dimensional lattice structure. During lithium ion insertion and removal, this structure maintains relative stability and resists structural breakdown or deformation. Consequently, the lithium-containing phosphate with an olivine structure can withstand multiple charge and discharge cycles without damage, thereby extending the battery's service life.

[0158] In the present disclosure, examples of lithium-containing phosphate with an olivine structure may include at least one of lithium iron phosphate (such as LiFePO4, also abbreviated as LFP), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate and a composite material of lithium manganese iron phosphate and carbon.

[0159] For example, the cathode collector has two surfaces that are opposite each other in its own thickness direction, with the cathode film layer arranged on one or two of the two opposite surfaces of the cathode collector.

[0160] In some embodiments, the lithium-containing phosphate with an olivine structure comprises a compound represented by formula (I): LiFe 1-x-y Mn x M 1 yPO4, Formula (I); where in Formula (I) M 1 at least one element from the group consisting of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn, and Pb; where 0 ≤ x ≤ 1 and 0 ≤ y < 1. The lattice structure of the lithium-containing phosphate is stable and resistant to phase transitions, further improving the safety performance of the secondary battery. For example, x is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value within the range formed by any two of these values. For example, y is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a value within the range formed by any two of these values.

[0161] In some embodiments, the first active cathode material further comprises a cathode coating layer arranged on at least a portion of the surface of the lithium-containing phosphate, wherein the cathode coating layer comprises at least one fast-ion conductor material and one carbon material. The carbon material is loosely porous, which enables thorough and effective contact between the electrolyte solution and the lithium iron phosphate matrix. This improves the wetting performance of the electrolyte solution on the cathode film layer and thus the fast-charging capability of the secondary battery. The fast-ion conductor material exhibits high ionic conductivity. The selection of a cathode coating layer containing the fast-ion conductor material enables improved fast-charging capability of the battery.

[0162] In certain embodiments, a cathode coating layer is arranged on the surface of the lithium-containing phosphate, wherein the cathode film layer comprises a fast ion conductor material and a carbon material.

[0163] In some embodiments, the cathode coating layer comprises a first coating layer and a second coating layer; the first coating layer comprising a fast-ion conductor material and the second coating layer comprising a carbon material; the first coating layer being positioned between the lithium-containing phosphate and the second coating layer. The carbon materials typically exhibit superior bonding properties. In this embodiment, applying the second coating layer, which contains carbon material, to the outer surface of the first active cathode material improves the bond strength between the first active cathode material and the current collector. During battery operation, this reduces the risk of the first active cathode material detaching, thereby extending the battery's lifetime.

[0164] In some embodiments, the cathode coating layer comprises a first coating layer and a second coating layer; wherein the first coating layer comprises a fast-ion conductor material and the second coating layer comprises a carbon material, the second coating layer being arranged between the lithium-containing phosphate and the first coating layer.

[0165] In this embodiment, during ion conduction, the lithium ions first penetrate the first coating layer, which is formed from the fast-ion conductor material, then pass into the second coating layer, and finally diffuse into the lithium-containing phosphate. This facilitates accelerated lithium ion migration within the first active cathode material and thus improves the battery's fast-charging capability. Furthermore, the carbon material in the second coating layer exhibits excellent electrical conductivity and forms a continuous conductive network between the lithium-containing phosphate and the first coating layer to accelerate electron conduction. This further enhances the battery's fast-charging capability.

[0166] In some embodiments, the mass ratio of the fast-ion conductor material to the carbon material in the cathode coating layer is (0-100):(100-0). Controlling the mass ratio of the fast-ion conductor material to the carbon material within the aforementioned range enables improved fast-charging capability of the battery. For example, the mass ratio of the fast-ion conductor material to the carbon material is 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, or a value within the range formed by any two of these values.

[0167] In some embodiments, the rapid ion conductor material comprises a compound represented by formula (II): Li 3-b Fe 2-b M 2 b (PO4)3, Formula (II); where in formula (II) M 2At least one element from the group consisting of Ti, Zr, Hf, Ge, and Sn is used, where 0 ≤ b ≤ 1. The aforementioned fast-ion conductor material exhibits excellent ionic conductivity. The selection of this fast-ion conductor material further improves the fast-charging capability of the battery. For example, b is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value within the range formed by any two of these values.

[0168] In some embodiments, the mass fraction of carbon in the first active cathode material is between 1% and 1.5%. Controlling the mass fraction of carbon in the first active cathode material within the aforementioned range makes it easier for the first active cathode material to achieve a high capacity, thus enabling the secondary battery to achieve a high energy density. Furthermore, it improves the electronic conductivity of the first active cathode material, thereby enhancing the fast-charging capability of the lithium-ion secondary battery.

[0169] The mass fraction of carbon in the present disclosure can be tested using methods known in this field. The cathode foils to be tested can be manufactured cathode foils or cathode foils obtained by dismantling batteries. In particular, when obtaining cathode foils from dismantled batteries, the cathode film layer is separated from the cathode collector. The cathode film layer is collected and dissolved with a suitable solvent, and then the first active cathode material is deposited. The mass fraction of carbon in the first active cathode material can be measured using a carbon-sulfur analyzer with reference to standard GB / T 20123-2006.

[0170] In some embodiments, the BET-specific surface area of ​​the first active cathode material is 12 m². 2 / g up to 16 m 2 / G.

[0171] If the BET-specific surface area of ​​the first active cathode material falls within the range mentioned above, the surface area of ​​the first active cathode material can offer more pathways for the insertion and removal of lithium ions. During fast charging, lithium ions can traverse these pathways more quickly to infiltrate the first active cathode material, thereby reducing both the transport distance and the resistance of the lithium ions, thus improving the battery's fast-charging capability. For example, the BET-specific surface area of ​​the first active cathode material is 12 m². 2 / g, 12.2 m 2 / g, 12.4 m 2 / g, 12.6 m 2 / g, 12.8 m 2 / g, 13 m 2 / g, 14 m 2 / g, 15 m 2 / g, 16 m 2 / g or a value within the range formed by any two values, is not limited to that.

[0172] In some embodiments, the bulk density of the first active cathode material is 0.8 g / cm³. 3 up to 1.3 g / cm³ 3 The bulk density of the first active cathode material within the aforementioned range facilitates the formation of numerous porous structures within the cathode film layer and ensures that the battery exhibits superior fast-charging capability. For example, the bulk density of the first active cathode material is 0.8 g / cm³. 3 , 1.1 g / cm³ 3 , 0.9 g / cm³ 3 , 1.0 g / cm³ 3 , 1.05 g / cm³ 3 , 1.15 g / cm³ 3 , 1.2 g / cm³ 3 , 1.25 g / cm³ 3 , 1.28 g / cm³ 3 , 1.3 g / cm³ 3 or a value within the range formed by any two values, but is not limited to that.

[0173] In some embodiments, the volume-averaged particle size of the first active cathode material is 1 µm to 3 µm. This facilitates the formation of numerous porous channel structures between the particles of the first active cathode material, improves the lithium ion and electron transport properties within the cathode film layer, and thereby improves the kinetic performance of the secondary battery. For example, the volume-averaged particle size Dv50 of the first active cathode material is 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, 2.1 µm, 2.2 µm, 2.3 µm, 2.4 µm, 2.5 µm, 2.6 µm, 2.7 µm, 2.8 µm, 2.9 µm, 3 µm, or a value within the range formed by any two values, but is not limited to this.

[0174] In some embodiments, the compression density of the first active cathode material at 50,000 N is 2.5 g / cm³. 3 up to 2.6 g / cm³ 3The density of the first active cathode material is within the range mentioned above. This results in denser contact between the particles of the first cathode material, thereby improving the energy density of the battery. For example, the density of the first active cathode material is 2.5 g / cm³. 3 , 2.51 g / cm³ 3 , 2.52 g / cm³ 3 , 2.53 g / cm³ 3 , 2.54 g / cm³ 3 , 2.55 g / cm³ 3 , 2.56 g / cm³ 3 , 2.57 g / cm³ 3 , 2.58 g / cm³ 3 , 2.59 g / cm³ 3 , 2.60 g / cm³ 3 or a value within the range formed by any two of these values.

[0175] In some embodiments, the active cathode material further comprises a second active cathode material, which includes a lithium transition metal oxide. The lithium transition metal oxide exhibits a higher specific capacity. The selection of the lithium transition metal oxide as the second active cathode material enables a further improvement in the energy density of the secondary battery.

[0176] In the present disclosure, examples of lithium transition metal oxides include at least one of the following: lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides (e.g., LiNi1 / 3Co1 / 3Mn1 / 3O2 (also abbreviated as NCM)). 333 ), LiNi 0,3 Co 0,2 Mn 0,3] O2 (also abbreviated as NCM) 523 ), LiNi 0,5 Co 0,25 Mn 0,25 O2 (also abbreviated as NCM) 211), LiNi 0,6 Co 0,2 Mn 0,2 O2 (also abbreviated as NCM) 622 ), LiNi 0,8 Co 0,1 Mn 0,1 O2 (also abbreviated as NCM) 811 ), lithium nickel cobalt aluminum oxides (e.g. LiNi 0,85 Co 0,1 Al 0,05 O2) and their modified compounds, but are not limited to these.

[0177] During the battery's charge and discharge cycles, lithium deintercalation and consumption occur, resulting in varying molar lithium content at different discharge states. In this disclosure, the molar lithium content in the listed active cathode materials refers to the material's initial state, i.e., the state before dosing. After the active cathode material has been used in a battery system and has undergone charge and discharge cycles, the molar lithium content is subject to changes.

[0178] In the present disclosure, the molar oxygen content in the listed active cathode materials refers only to the theoretical value. Lattice-related oxygen release leads to changes in the molar oxygen content, so that the actual molar oxygen content is subject to fluctuations.

[0179] In some embodiments, the mass ratio of the first active cathode material to the second active cathode material is (99-90):(1-10). Controlling the mass ratio of the first active cathode material to the second active cathode material within the aforementioned range facilitates a balance between the lifetime and energy density of the secondary battery. For example, the mass ratio of the first active cathode material to the second active cathode material is 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 90:10, or a value within the range formed by any two of these values.

[0180] In some embodiments, the thickness of the cathode film layer arranged on one side of the cathode collector is 100 µm to 200 µm. Controlling the thickness of the cathode film layer within the aforementioned range allows the cathode film layer to achieve both high capacity and good lithium-ion and electron transport properties, enabling the secondary battery to achieve a balance between high energy density and fast-charging capability. For example, the thickness of the cathode film layer can be 100 µm, 110 µm, 120 µm, 130 µm, 140 µm, 150 µm, 160 µm, 170 µm, 180 µm, 190 µm, 200 µm, or a value within the range formed by any two of these values.

[0181] In some embodiments, the coating weight of the cathode film layer arranged on one side of the cathode collector is 200 mg / 1540.25 mm². 2 up to 400 mg / 1540.25 mm 2Controlling the coating weight of the cathode film layer within the aforementioned range allows for an increase in the number of lithium ions released per unit area of ​​the cathode film layer, thereby improving the battery's energy density. For example, the coating weight of the cathode film layer is 200 mg / 1540.25 mm². 2 , 220 mg / 1540.25 mm 2 , 240 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 , 360 mg / 1540.25 mm 2 , 370 mg / 1540.25 mm 2 , 380 mg / 1540.25 mm 2 , 390 mg / 1540.25 mm 2 , 400 mg / 1540.25 mm 2or a value within the range formed by any two values. Optionally, the coating weight of the cathode film layer is 250 / 1540.25 mm³. 2 up to 320 / 1540.25 mm 2 .

[0182] The coating weight of the cathode film layer in the present disclosure can be tested using methods known in this field. The cathode films to be tested can be manufactured cathode films or cathode films obtained by dismantling batteries. In particular, if a cathode film is obtained from a dismantled battery, the cathode film is formed into a circular disk with an area of ​​1540.25 mm². 2 The circular disk is cut. The mass of the resulting disc is weighed as m7. Then, the cathode film layer is removed from one side of the circular disk, and the mass of the disk is weighed again as m8. The difference between m7 and m8 is taken as the coating weight of the cathode film layer.

[0183] In some embodiments, the density of the cathode film layer is 2 g / cm³. 3 up to 3 g / cm² 3 Controlling the cathode film layer's packing density within the aforementioned range makes it easier for the cathode film layer to maintain a better porous structure, reduce its tortuosity, and shorten the lithium-ion transport pathways. This improves the battery's fast-charging capability and lifespan while simultaneously achieving high energy density. For example, the cathode film layer packing density can be 2 g / cm³. 3 , 2.1 g / cm³ 3 , 2.2 g / cm³ 3 , 2.3 g / cm³ 3 , 2.4 g / cm³ 3 , 2.5 g / cm³ 3 , 2.60 g / cm³ 3 , 2.7 g / cm³ 3 , 2.8 g / cm³ 3 , 2.9 g / cm³ 3 , 3 g / cm 3or a value within the range formed by any two of these values. Optionally, the density of the cathode film layer is 2.3 g / cm³. 3 up to 2.5 g / cm³ 3 .

[0184] In some embodiments, the cathode collector has a thickness of 10 µm to 18 µm. This thickness range allows the battery to achieve a high energy density and also helps to reduce the risk of cracking in the cathode collector, thus extending the battery's lifespan. For example, the cathode collector thickness may be 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 14.5 µm, 15 µm, 15.5 µm, 16 µm, 16.5 µm, 17 µm, 17.5 µm, 18 µm, or a value within the range formed by any two of these values. Optionally, the thickness of the cathode collector is 13 µm to 15 µm.

[0185] In some embodiments, the cathode collector can be a metal foil or a composite collector. For example, an aluminum foil can be used as the metal foil. The composite collector can comprise a base layer of polymeric material and a metal layer formed on at least one surface of the polymeric base layer. The composite collector can be formed by depositing metallic material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0186] In some embodiments, the cathode film layer optionally comprises a binder. For example, the binder may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0187] In some embodiments, the cathode film layer optionally further comprises a conductive agent. For example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dot, carbon nanotubes, graphene, and carbon nanofibers.

[0188] In some embodiments, the cathode film layer further comprises a cathode dispersion agent, which includes at least one compound from the group consisting of polyethylene glycol octylphenyl ether, polyvinylpyrrolidone, and sodium carboxymethylcellulose. The aforementioned cathode dispersion agent exhibits excellent flexibility and elasticity, enabling it to dissipate stresses to which the active cathode material is subjected during compaction. The selection of this cathode dispersion agent facilitates the achievement of a high compaction density within the cathode film layer, thereby increasing the energy density of the battery.

[0189] In some embodiments, the mass fraction of the cathode dispersion medium relative to the cathode film layer is 0.3% to 5%. Optionally, it can be 0.1% to 2%, further optionally 0.1% to 1%, and still further optionally 0.5% to 0.8%. By controlling the mass fraction of the cathode dispersion medium in the cathode film layer within the aforementioned range, the battery is better able to achieve a high energy density. For example, the mass fraction of the cathode dispersion medium is 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, and 5%, or a value within the range formed by any two of these values.

[0190] In some embodiments, the cathode foil can be produced as follows: Dispersing the components described above for the production of the cathode foil, such as the active cathode material, the conductive agent, the binder and other components, in a solvent (e.g. N-methylpyrrolidone) to form a cathode slurry; applying the cathode slurry to the cathode collector and obtaining the cathode foil after drying, cold pressing and other processes. electrolyte

[0191] The electrolyte serves as an ion conductor between the cathode foil and the anode foil. This disclosure does not impose any specific restrictions regarding the type of electrolyte, which can be selected as needed. For example, the electrolyte can be in liquid, gel, or solid form.

[0192] In some embodiments, an electrolyte solution is used for the electrolyte. This electrolyte solution consists of an electrolyte salt and a solvent.

[0193] In some embodiments, the electrolyte salt may be at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluorosulfonyl)amide, lithium bis(trifluoromethanesulfonyl)amide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalic acid borate, lithium di(oxalic acid)borate, lithium difluorodioxygenophosphate and lithium tetrafluorooxalic acid phosphate.

[0194] In some embodiments, the solvent may be at least one of ethylidene carbonate, propylidene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylenepropyl carbonate, ethylenepropyl carbonate, butylidene carbonate, ethylidene fluorocarbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0195] In some embodiments, the electrolyte solution further comprises an additive, wherein the additive includes at least one compound from the group consisting of barium sulfate, poly(trifluoroethyl methacrylate), bicyclosulfate, tricyclosulfate, tris(trimethylsilyl) phosphate, and vinylene carbonate. During the first charge-discharge cycle of the battery, the aforementioned additives undergo electrochemical reduction reactions on the surface of the anode foil in front of the solvent molecules in the electrolyte solution, forming a dense, stable SEI film. This facilitates the suppression of lithium dendrite growth and improves the battery's safety performance.

[0196] In some embodiments, the mass fraction of the additive in the electrolyte solution ranges from 1% to 10%. Controlling the mass fraction of the additive within the aforementioned range facilitates the formation of a suitable thickness of SEI film on the electrode surface. On the one hand, this suppresses the growth of lithium dendrites and improves the battery's safety performance. On the other hand, it helps to achieve a balance between the lithium-ion transfer resistance within the anode foil and the battery's fast-charging capability. For example, the mass fraction of the additive can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a value within the range formed by any two of these values.

[0197] In some embodiments, the electrical conductivity of the electrolyte solution is between 10 mS / cm and 18.5 mS / cm. Selecting an electrolyte solution with an electrical conductivity within the aforementioned range can reduce the battery's internal resistance and minimize energy losses due to resistance during charge and discharge cycles, thereby extending the battery's lifespan. For example, the electrical conductivity of the electrolyte solution may be 10 mS / cm, 11 mS / cm, 12 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 18.5 mS / cm, or a value within the range formed by any two of these values. Optionally, the electrical conductivity of the electrolyte solution may be between 14 mS / cm and 16.8 mS / cm.

[0198] In some embodiments, the electrolyte solution optionally includes an additive. For example, it may include an additive that can improve certain battery properties, such as an additive to improve the battery's overcharge performance, an additive to improve the battery's high or low temperature performance, etc.

[0199] In some embodiments, the cathode foil, the anode foil and the separating film can be assembled into an electrode component by a winding process or a stacking process.

[0200] In some embodiments, the battery cell may include an outer casing. The outer casing can be used to encapsulate the electrode component and electrolyte described above.

[0201] In some embodiments, the outer packaging of the battery cell can be a rigid casing, such as a hard plastic casing, an aluminum casing, a steel casing, etc. The outer packaging of the battery cell can also be a flexible casing, such as a bag-like soft casing. The flexible casing can be made of plastic, and examples of such plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0202] The present disclosure does not subject the shape of the battery cell to any particular restrictions, so that it can be cylindrical, square, or in any other shape. For example, it shows Fig. 1 a square structured battery cell 5 as an example.

[0203] In some embodiments, such as in Fig.As shown in Figure 2, the outer packaging can comprise a housing 51 and a cover plate 53. The housing 51 can include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening that communicates with the receiving cavity, and the cover plate 53 can cover the opening to close the receiving cavity. The cathode foil, the anode foil, and the separator film can be assembled into an electrode component 52 by a winding or stacking process. The electrode component 52 is encapsulated in the receiving cavity. The electrolyte solution permeates the electrode component 52. The number of electrode components 52 contained in the battery cell 5 can be one or more, selected by those skilled in the art according to the specific practical requirements.

[0204] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells contained in the battery module can be 1 or more than 1, the exact number being selected by experts in this field depending on the application and capacity of the battery module.

[0205] Fig. Figure 3 shows a battery module 4 as an example. With reference to Fig. 3. The multiple battery cells 5 in the battery module 4 can be arranged sequentially along a longitudinal direction of the battery module 4. Of course, they can also be arranged in any other desired way. Furthermore, the multiple battery cells 5 can be fastened by means of fastening elements.

[0206] Optionally, the battery module 4 can also include a casing with a receiving space in which several battery cells 5 are housed.

[0207] In some embodiments, the battery cells can be assembled into a battery pack, and the number of battery cells contained in the battery pack can be 1 or more than 1, with the exact number being selected by experts in this field depending on the application and capacity of the battery module.

[0208] Fig. 4 and Fig. Figure 5 shows a battery pack 1 as an example. As in Fig. 4 and Fig. As shown in Figure 5, the battery pack 1 can comprise a battery housing and a plurality of battery modules 4 arranged within the battery housing. The battery housing comprises an upper housing 2 and a lower housing 3, wherein the upper housing 2 can cover the lower housing 3 and form an enclosed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged within the battery housing in any desired configuration. Power-consuming device

[0209] The present disclosure further provides a power-consuming device comprising a secondary battery provided by the first aspect of the present disclosure, which may include at least one battery cell, one battery module, and one battery pack. The secondary battery may be used as a power source for the power-consuming device or as an energy storage unit for the power-consuming device. The power-consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0210] Depending on requirements, the power-consuming device can be a battery cell, a battery module or a battery pack.

[0211] Fig. Figure 6 shows an example of a power-consuming device. This device could be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery of this power-consuming device, a battery pack or battery module can be used.

[0212] Another example of such a device is a mobile phone, a tablet, a laptop, etc. The device usually needs to be light and thin and can use a battery cell as a power source. Example of implementation

[0213] The following describes exemplary embodiments of the present disclosure. These embodiments are examples, serve only to illustrate the present disclosure, and cannot be construed as limiting it. Unless specific techniques or conditions are indicated in the exemplary embodiments, they correspond to those described in the relevant literature or the product specifications. Any reagents or instruments used without manufacturer identification are commercially available products. I. Production of the first graphite material and the second graphite material: Production example 1-1 Production of the first graphite material (Material 1-1):

[0214] Step 1: Crushing and shaping the oil-based calcined needle coke feedstock using a jet mill to obtain shaped material with a Dv50 value of 15 µm;

[0215] Step 2: Using granulated asphalt (softening point 125°C; coking value 51%) as a granulating agent, the formed material and the granulating agent are granulated together in a granulation reactor in a mass ratio of 88:7 to produce granulated material;

[0216] Step 3: the granulated material is pre-carbonized for 5.2 hours at 1450°C under a nitrogen atmosphere to obtain an intermediate product;

[0217] Step 4: the intermediate product is subjected to graphitization at 3000°C, and the graphitized particles are sieved and demagnetized to obtain the first graphite material. Production example 2-1 Production of the second graphite material (material 2-1):

[0218] Step 1: Crushing and shaping the oil-based calcined needle coke feedstock using a jet mill to obtain shaped material with a Dv50 value of 22 µm;

[0219] Step 2: Using granulated asphalt (softening point 113°C; coking value 66%) as a granulating agent, the formed material and the granulating agent are granulated together in a granulation reactor in a mass ratio of 90:6 to produce granulated material;

[0220] Step 3: the granulated material is pre-carbonized for 4.7 hours at 1480°C under a nitrogen atmosphere to obtain an intermediate product;

[0221] Step 4: the intermediate product is subjected to graphitization at 3000°C, and the graphitized particles are sieved and demagnetized to obtain the second graphite material. II. Testing of the first graphite material and the second graphite material:(1) I D / I G-Test:

[0222] The samples are tested using a Raman spectrometer.

[0223] The test conditions are as follows: excitation wavelength 532 nm, 600 lines / mm grating, 50× objective lens, 10-second integration time, 3 cumulative measurements, surface scan. This yields D- and G-peak intensities at 100 points. D / I G The ratio is calculated for these 100 points, where the maximum and minimum 30 I D / I G -ratioes are excluded. The average of the remaining 40 points forms the I. D / I G -ratio of the material. The Horiba LabRAM HR800 Raman spectrometer can be used as a test instrument.

[0224] Material 1-1 has an I D / I G -ratio of 0.51. Material 2-1 exhibits an I D / I G -ratio of 0.13. (2) Testing of volume-averaged particle size Dv50:

[0225] The measurement can be performed according to GB / T 19077-2016 using a laser particle size analyzer. The test instrument can be the Mastersizer 3000 laser particle size analyzer from Malvern Instruments GmbH.

[0226] Material 1-1 has a Dv50 of 11.8 µm. Material 2-1 has a Dv50 of 18.3 µm. (3) Testing of the BET-specific surface:

[0227] The test can be performed according to GB / T 19587-2017 using the specific surface area analysis method by nitrogen adsorption, whereby the BET-specific surface area is determined using the BET method (Brunauer Emmett Teller). The testing instrument can be the Tri-Star 3020 Specific Surface Area and Pore Size Analyzer manufactured by Micromeritics, USA.

[0228] Material 1-1 has a specific BET surface area of ​​0.94 m². 2 / g. Material 2-1 has a specific BET surface area of ​​1.78 m².2 / g on. (4) Testing the bulk density:

[0229] The measurement is carried out according to GB / T 5162-2006 using a powder bulk density meter. The test instrument can be the Dandong Baite BT-301 model with the following parameters: shaking frequency 250±15 strokes / minute, amplitude 3±0.2 mm, number of shakes 5000 strokes, measuring cylinder 25 mL.

[0230] Material 1-1 has a bulk density of 1.1 g / cm³. 3 The material 2-1 has a bulk density of 1.05 g / cm³. 3 on. Table 1 number I D / I G Dv50 (µm) BET (m 2 / g) Bulk density (g / cm³) 3 ) First graphite material Material 1-1 0,51 11,8 0,94 1,1 Second graphite material Material 2-1 0,13 18,3 1,78 1,05 III. Production of the anode slurry. Production example 3-1

[0231] The first graphite material (material 1-1 according to Table 1), the first binder (styrene-butadiene rubber and lithium polyacrylate in a mass ratio of 2:1), the first dispersion agent (carboxymethylcellulose-lithium), and the first conductive agent (carbon nanotubes and conductive carbon black in a mass ratio of 5:5) are mixed in a mass ratio of 96.6:1.8:0.9:0.7 to produce the first anode slurry. Production example 3-2

[0232] The second graphite material (material 1-2 according to Table 1), the second binder (styrene-butadiene rubber and lithium polyacrylate in a mass ratio of 2:1.3), the second dispersion agent (carboxymethylcellulose-lithium) and the second conductive agent (carbon nanotubes and conductive carbon black in a mass ratio of 5:5) are mixed in a mass ratio of 97.8:1:0.7:0.5 to produce the second anode slurry. Production example 3-3

[0233] The active anode material (material 1-1 and material 2-1 in a mass ratio of 5:5), the second binder (styrene-butadiene rubber and lithium polyacrylate in a mass ratio of 2:1), the second dispersion agent (carboxymethylcellulose-lithium) and the second conductive agent (carbon nanotubes and conductive carbon black in a mass ratio of 5:5) are mixed in a mass ratio of 96.9:1.8:0.8:0.5 to produce the third anode slurry. IV. Production of the secondary battery: Example 11. Production of the cathode foil:

[0234] The active cathode material (first active cathode material, lithium iron phosphate), conductive carbon black, polyvinylidene fluoride (PVDF), and cathode dispersion agent (polyethylene glycol octylphenyl ether) are mixed in a mass ratio of 97.6:0.1:1.8:0.5. The mixture is then added to N-methylpyrrolidone solvent and stirred thoroughly to obtain the cathode slurry. Both surfaces of the cathode collector aluminum foil are coated with the cathode slurry. After drying and cold pressing, the cathode foil is obtained. 2. Production of the anode foil:

[0235] Using a two-chamber coating device, the first and second anode slurries are simultaneously extruded in a 5:5 mass ratio. After drying and cold pressing, the anode foil is obtained. The second anode slurry forms a second film layer when applied to the anode collector (copper foil), while the first anode slurry forms a first film layer on the side of the second anode slurry facing away from the anode collector. After subsequent drying, cold pressing, and cutting, the anode foil is obtained. 3. Preparation of the electrolyte solution:

[0236] A mixture of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) is mixed in a volume ratio of 3:7 to form the organic solvent. A film-forming agent (barium sulfate, 2.5% by mass) is added. LiPF6 is dissolved in the aforementioned organic solution to obtain an electrolyte solution with a LiPF6 concentration of 1 mol / L. 4. Separating film:

[0237] A polyethylene base film with a thickness of 5 µm is used. Both sides of the base film are coated with a layer of heat-resistant particles. These particles consist of boehmite particles (inorganic particles) and a bonding layer applied to the surface of the boehmite particles. 5. Production of the secondary battery:

[0238] The cathode foil, separator film, and anode foil are stacked sequentially, with the separator film positioned between the cathode and anode foils to provide insulation. They are then folded and wound to form an electrode assembly. The electrode assembly is placed in an outer packaging, dried, and filled with the prepared electrolyte solution. After vacuum encapsulation, resting, forming, and shaping, the secondary battery is obtained. V. Examination of the morphology of the separating film:

[0239] The release film is placed in a sample holder, where it is locked and secured. Cross-sectional SEM images of the release film are acquired using a scanning electron microscope (HR-TEM Talos F200), as shown in Fig. Figure 7 shows that the cross-sectional SEM images reveal that the coating consists of heat-resistant particles that intertwine to form a porous structure. VI. Testing of the compression density:(1) Testing of the compression density of the cathode film layer:

[0240] First, the cathode film layer is wiped from one side of the cathode foil, and the cathode foil is punched into a small circular disc with an area of ​​S21. The weight is recorded as M21, and the thickness H21 is measured. Then, the cathode film layer of the cathode foil, which was weighed as described above, is wiped off, and the weight of one cathode collector is recorded as M20, and the thickness H20 is measured. One-sided coating weight of the cathode foil = (M21 - weight of the positive current collector M20) / S21. Thickness of the cathode film layer = H21 - H20. Compression density of the cathode film layer = One-sided coating weight of the cathode film layer / Thickness of the cathode film layer. (2) Testing the compression density of the anode film layer:

[0241] First, the anode film layer is wiped from one side of the anode foil, and the anode foil is punched into a small circular disc with an area of ​​S11. The weight is recorded as M11, and the thickness H11 is measured. Then, the anode film layer of the anode foil, weighed as described above, is wiped off, and the weight of one anode collector is recorded as M10, and the thickness H10 is measured. One-sided coating weight of the anode foil = (M11 - M10) / S11. Thickness of the anode film layer = H11 - H10. Press density of the anode film layer = One-sided coating weight of the anode film layer / Thickness of the anode film layer. VII. Performance testing of the secondary battery:(1) Energy density testing:

[0242] Charge the battery cell at 25°C with a constant current of 0.33C until a cut-off voltage of 3.65V is reached. Then charge at a constant voltage of 3.65V until the current reaches 0.05C. At this point, the secondary battery is fully charged. Allow the fully charged secondary battery to rest for 5 minutes, then discharge it with a constant current of 0.33C until the cut-off voltage of 2.5V is reached. The discharge capacity at this point corresponds to the actual capacity of the secondary battery at 0.33C, denoted as C0.

[0243] Then charge the secondary battery with a constant current of 0.33 Co until the cut-off voltage of 3.65 V and continue charging at a constant voltage until the current reaches 0.05 C. At this point, the secondary battery is fully charged. Let the fully charged secondary battery rest for 5 minutes and then discharge it with a constant current of 0.33 Co until the cut-off voltage of 2.5 V is reached to determine the discharge energy Q of the secondary battery. The energy density (Wh / kg) of the secondary battery = Discharged energy Q of the secondary battery / Mass M of the secondary battery.

[0244] The test results are listed in Table 2 below. (2) Examination of the security deposit:

[0245] Placing a fully charged secondary battery in a heating box; The temperature of the heating box is gradually increased at a constant heating rate (3°C / min); The secondary battery is monitored for changes, and the heating process is stopped if thermal runaway occurs in the secondary battery; The maximum temperature reached during the thermal runaway of the secondary battery is recorded. Examples 2 to 3

[0246] In embodiments 2 and 3, the same method for manufacturing the secondary battery is used as in embodiment 1, the difference being in the following aspects:

[0247] Adjusting the cold pressing process of the cathode foil to achieve the cathode film layer pressing density specified in Table 2.

[0248] Adjusting the cold pressing process of the anode foil to achieve the pressing density of the anode film layer specified in Table 2. Examples 4 to 7

[0249] In embodiments 4 to 7, the same method for manufacturing the secondary battery is used as in embodiment 1, the difference being that a base film with corresponding thicknesses is used as specified in Table 2. Comparison examples 1 and 2

[0250] In comparative examples 1 and 2, the same method for manufacturing the secondary battery is used as in comparative example 1, the difference being that a base film with corresponding thicknesses is used, as specified in Table 2.

[0251] The performance of the secondary batteries produced in embodiments 2 to 7 and comparative examples 1 and 2 is tested using the same procedure as in embodiment 1. The test results are listed in Table 2. Table 2 Item cathode film layer Anode film layer Basic film Secondary battery Density (g / cm³) 3 ) Density (g / cm³) 3 ) Thickness (µm) Average nanopore diameter (nm) Porosity(%) Energy density (Wh / kg) Maximum temperature of thermal run-through (°C) Example 1 2,7 1,62 5 60 38 182 260 Example 2 2,0 1,4 172 249 Example 3 3,0 1,85 188 270 Example 4 2,7 1,62 4 186 265 Example 5 7 180,5 258 Example 6 9 176 255 Example 7 12 174 252 Comparative example 1 2,7 1,62 3 60 38 187 310 Comparative example 2 16 168 251

[0252] In the embodiments described in this disclosure, the maximum temperature during thermal runaway characterizes the safety performance of the secondary battery. A higher maximum temperature during thermal runaway indicates poorer safety performance of the battery. A maximum thermal runaway temperature exceeding 300°C can trigger thermal propagation and significantly impair the battery's safety performance.

[0253] In comparison to example 1 (where the base film thickness is less than 4 µm), the secondary batteries produced in embodiments 1 to 7 exhibit improved safety performance.

[0254] By comparing the data from comparison example 2, it can be determined that with a base film thickness of more than 12 µm, a further increase in thickness has only a limited impact on improving battery safety performance, while at the same time reducing the energy density of the battery.

[0255] In embodiments 1 to 7, the manufactured secondary batteries had a base film thickness between 4 µm and 12 µm. Such batteries ensured better safety performance while maintaining a higher energy density. Examples 8 to 11

[0256] In embodiments 8 and 11, the same method for manufacturing the secondary battery is used as in embodiment 1, the difference being that the coating parameters are adjusted according to the records in Tables 3-1. Example 12

[0257] In embodiment 12, the same method for manufacturing the secondary battery is used as in embodiment 1, the difference being that the heat-resistant particles consist of boehmite particles and PVDF particles.

[0258] The performance of the secondary batteries produced in embodiments 8 to 12 is tested using the same procedure as in embodiment 1. The test results are listed in Table 3-2. Table 3-1 Item Coating parameters Thickness (µm) Average particle size (nm) Morphology of heat-resistant particles Surface density (mg / 1540.25cm²) 2 ) Whether the first particles are preserved Whether second particles are preserved Mass fraction of inorganic particles (%) Example 1 1 70 Inorganic particles and bonding layer with which the surfaces of the inorganic particles are coated. 1,1 Yes no 18 Example 8 0,011 5 0,5 no 5 Example 9 1,2 100 1,25 no 10 Example 10 1,6 130 1,85 no 25 Example 11 2 185 2,5 Yes 30 Example 12 1 70 Inorganic particles and binding particles 1,1 no 18 Table 3-2 Item Secondary battery Energy density (Wh / kg) Maximum temperature of thermal runaway (°C) Example 1 182 260 Example 8 186 265 Example 9 181 251 Example 10 180,2 244 Example 11 178 238 Example 12 182 258

[0259] The data from Tables 3-1 and 3-2 show that the manufactured secondary battery achieves both good safety performance and high energy density when the coating thickness is 0.011 µm to 2 µm, the average particle size of the heat-resistant particles is 5 nm to 185 nm, and the particle area density of the heat-resistant particles is 0.5 mg / 1540.25 cm². 2 up to 2.5 mg / 1540.25 cm 2 amounts. Example 13

[0260] In embodiment 13, the same method for manufacturing the secondary battery is used as in embodiment 1, the difference being that

[0261] that in the production of the anode foil, the second anode slurry is replaced by the third anode slurry. Examples 14 to 17

[0262] In embodiments 14 to 17, the same method for manufacturing the secondary battery is used as in embodiment 13, the difference being that

[0263] that during the manufacture of the anode foil, the mass ratio of the first graphite material to the second graphite material within the third anode slurry is adjusted and / or the mass ratio of the first anode slurry to the second anode slurry is adjusted (according to the thickness ratio of the first and second film layers within the anode foil), as specified in Table 4. Fast charging capability test:

[0264] At 25°C, the secondary battery is charged with a constant current of 0.33C up to a cutoff voltage of 3.65V, and then charged with a constant voltage until the current reaches 0.05C. After a 5-minute rest period, the secondary battery is discharged with a constant current of 0.33C up to a cutoff voltage of 2.5V, with its actual capacity recorded as C0.

[0265] The secondary battery is then charged successively with constant currents of 1.0 C, 1.3 C, 1.5 C, 1.8 C, 2 C, 2.3 C, 2.5 C, and 3.0 C until either the charging cutoff voltage of 3.65 V or the negative electrode cutoff potential of 0 mV (whichever comes first) is reached. After each charge cycle, the battery is discharged at 1 C until the discharge cutoff voltage of 2.5 V is reached. The corresponding negative potential is recorded at 10% SOC, 20% SOC, 30% SOC, 40% SOC, 50% SOC, 60% SOC, 70% SOC, and 80% SOC (state of charge) for each charge rate.

[0266] Charge rate-negative potential curves for various state-of-charge (SOC) states are recorded. Linear fitting determines the charge rate corresponding to a negative potential of 0 V for each SOC state. This charge rate represents the charging window for the respective SOC state and is accordingly denoted as C. 10%SOC , C 20%SOC , C 30%SOC , C 40%SOC , C 50%SOC, C 60%SOC , C 70%SOC and C 80%SOC designated.

[0267] Using the following formula: (60 / C10%SOC+60 / C20%SOC+60 / C30%SOC+60 / C40%SOC+60 / C50%SOC+60 / C60%SOC+60 / C70%SOC+60 / C80%SOC)×10% The charging time T (in minutes) for charging the secondary battery from 10% SOC to 80% SOC is calculated (assuming no lithium deposition occurs in the secondary battery). The test results are listed in Table 4.

[0268] The safety performance and energy density of the secondary batteries produced in embodiments 13 to 17 are tested using the same procedure as in embodiment 1. The test results are listed in Table 4. Table 4 Item Anode foil Secondary battery Second film layer Thickness ratio of the first film layer to the second film layer mass ratio Energy density (Wh / kg) Maximum temperature of thermal runaway (°C) Fast charging time (min) Example 1 10:0 5:5 186 260 40 Example 13 5:5 186 251 32 Example 14 4:6 183 252 31 Example 15 3:7 182 255 29 Example 16 5:5 4:6 183 251 33 Example 17 3:7 183 250 35

[0269] The “mass ratio” in Table 4 refers to the mass ratio of the second graphite material to the first graphite material.

[0270] The data in Table 4 show that the manufactured secondary battery achieves a balance between safety performance and energy density while further improving its fast-charging capability when the second electrode layer includes both the first graphite material and the second graphite material. Examples 18 to 22

[0271] In embodiments 18 to 22, the same method for manufacturing the secondary battery is used as in embodiment 13, the difference being that that the batteries are manufactured using the first active cathode material listed in Table 5-1. The parameters for each first active cathode material are listed in Table 5-2.

[0272] The performance of the secondary batteries produced in embodiments 18 to 22 is tested using the same procedure as in embodiment 1. The test results are listed in Table 5-2. Table 5-1 Item First active cathode material Lithium-containing phosphate cathode coating layer Mass fraction of carbon First coating layer Second coating layer Positional relationship between the first coating layer and the second coating layer Mass ratio of fast-ion conductor material to carbon material Example 13 Lithium iron phosphate / / / / 0 Example 18 Lithium iron manganese phosphate / / / / 0 Example 19 Lithium iron phosphate Li2FeSn(PO4)3 / / 100:0 0 Example 20 Lithium iron phosphate / Carbon material / 0:100 1,5 Example 21 Lithium iron phosphate Li2FeSn(PO4)3 Carbon material The first coating layer is positioned between the lithium-containing phosphate and the second coating layer. 1:2 1 Example 22 Lithium iron phosphate Li2FeSn(PO4)3 Carbon material The second coating layer is positioned between the lithium-containing phosphate and the first coating layer. 1:2 1 Table 5-2 Item Parameters of the first active cathode material Secondary battery BET (m 2 / g) Bulk density (g / cm³) 3 ) Dv50 (µm) Density (g / cm³) 3 ) Fast charging time (min) Example 13 14 1,1 1,8 2,6 32 Example 18 15,5 1,09 2 2,4 31 Example 19 14,2 1,07 1,9 2,5 28 Example 20 14,6 1,03 2,1 2,55 26 Example 21 14,5 1,06 2,03 2,51 25 Example 22 14,4 1,05 1,98 2,53 25

[0273] The data from Tables 5-1 to 5-2 show that the incorporation of fast ion conductor materials and / or carbon materials into the cathode coating layer further improves the fast charging capability of the manufactured secondary batteries. Examples 23 to 25

[0274] In embodiments 23 to 25, the same method for manufacturing the secondary battery is used as in embodiment 13, the difference being that at least one of the following parameters is adjusted according to Table 6-1: the ratio of the components in the active cathode material, the coating weight of the cathode slurry or the thickness of the cathode collector.

[0275] The performance of the secondary batteries produced in embodiments 23 to 25 is tested using the same procedure as in embodiment 1. The test results are listed in Table 6-2. Table 6-1 Item Active cathode material cathode foil Cathode collector thickness (µm) First active cathode material Second active cathode material mass ratio One-sided coating weight of the cathode film layer (mg / 1540.25mm²) 2 ) Density (g / cm³) 3 ) Example 13 Lithium iron phosphate / 100:0 290 2,63 13 Example 23 Lithium iron phosphate NCM 811 99:1 200 2 18 Example 24 Lithium iron phosphate NCM 811 95:5 300 3 15 Example 25 Lithium iron phosphate NCM 811 90:10 400 2 10

[0276] The “mass ratio” in Table 6-1 refers to the mass ratio of the first active cathode material to the second active cathode material. Table 6-2 Item Secondary battery Energy density (Wh / kg) Example 13 182 Example 23 187 Example 24 192 Example 25 198

[0277] The data from Tables 6-1 to 6-2 show that the energy density of the resulting secondary battery is further increased when the cathode film layer is completely covered with lithium transition metal oxide (NCM). 811 ) is loaded. Examples 26 and 27

[0278] In embodiments 26 and 27, the same method for producing the secondary battery is used as in embodiment 13, the difference being that the type or amount of the cathode dispersion medium (mass fraction in the cathode film layer) is adapted according to Table 7 and the type or amount of the additive (mass fraction in the electrolyte solution) is adapted according to Table 7.

[0279] The performance of the secondary batteries produced in embodiments 26 and 27 is tested using the same procedure as in embodiment 1. The test results are listed in Table 7. Table 7 Item cathode foil electrolyte solution Secondary battery Cathode dispersion medium Additive Electrical conductivity (S / cm) Energy density (Wh / kg) Maximum temperature of thermal run-through (°C) type Mass ratio (%) Mass ratio (%) type Example 13 Polyethylene glycoloctyl phenyl ether 0,5 2,3 Barium sulfate 16,3 182 251 Example 26 Polyvinylpyrrolidone 1,2 10 Poly(trifluoroethyl methacrylate) 16,3 182 250 Example 27 Sodium CarboxyMethyl Cellulose 0,3 1 Bis(cyclohexyl) sulfate 15,8 182 256

[0280] The data in Table 7 show that secondary batteries can achieve a balance between energy density and safety performance when the mass fraction of the cathode dispersion medium in the cathode foil is 0.3% to 5% and the mass fraction of the additives in the electrolyte solution is 1% to 10%.

[0281] It should be noted that the present disclosure is not limited to the embodiments mentioned above. The embodiments mentioned above are only examples, and embodiments within the scope of the technical solution of the present disclosure that have essentially the same composition as the technical idea and have the same effect are included within the technical scope of the present disclosure. Furthermore, within the scope of the present disclosure, the present application also includes other ways of constructing the embodiments by combining some of the constituent elements of the embodiments and applying various deformations to the embodiments, which a person skilled in the art can imagine without departing from the subject matter of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] CN 202510932503.0

[0001] Cited non-patent literature

[0000] GB / T 19587-2017

[0116] GB / T 19077-2016

[0225]

Claims

[1] Secondary battery comprising a cathode foil, an anode foil and a separating film, wherein, the cathode foil comprises a cathode collector and a cathode film layer arranged on the surface of at least one side of the cathode collector, wherein the density of the cathode film layer is 2.0 g / cm³ 3 up to 3.0 g / cm³ 3 amounts; wherein the anode foil comprises an anode collector and an anode film layer arranged on at least one surface of the anode collector, wherein the density of the anode film layer is 1.4 g / cm³ 3 up to 1.85 g / cm³ 3 amounts; wherein the separating film comprises a base film having a thickness of 4 µm to 12 µm, wherein the base film has nanopores having an average pore size of 10 nm to 300 nm. [2] Secondary battery according to claim 1, wherein the base film has a thickness of 5 µm to 9 µm. [3] Secondary battery according to claim 1, wherein the base film has a porosity of 20% to 70%. [4] Secondary battery according to claim 1, wherein the separating film further comprises a coating arranged on at least one side of the base film, the coating comprising heat-resistant particles woven into a porous structure. [5] Secondary battery according to claim 4, wherein the coating arranged on at least one side of the base film has a thickness of 0.011 µm to 3 µm. [6] Secondary battery according to claim 4, wherein the heat-resistant particles have an average particle size of 5 nm to 185 nm. [7] Secondary battery according to claim 4, wherein the particle area density of the heat-resistant particles is 0.5 mg / 1540.25 cm² 2 up to 2.5 mg / 1540.25 cm 2 amounts. [8] Secondary battery according to claim 4, wherein along the thickness direction of the base film the heat-resistant particles comprise first heat-resistant particles; or wherein the heat-resistant particles comprise first heat-resistant particles and second heat-resistant particles; wherein the first heat-resistant particles are distributed on the surface of the base film, and wherein the second heat-resistant particles are stacked on a side of the first heat-resistant particles facing away from the base film. [9] Secondary battery according to claim 4, wherein the heat-resistant particles comprise inorganic particles and bonding particles, and / or wherein the heat-resistant particles comprise inorganic particles and a bonding layer arranged on at least a part of the surface of the inorganic particles. [10] Secondary battery according to claim 9, wherein the inorganic particles comprise at least one compound from the group consisting of aluminium trioxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, boehmite, magnesium oxide, zinc oxide, barium sulfate, magnesium nitride and barium titanate. [11] Secondary battery according to claim 9, wherein the mass fraction of the inorganic particles in the coating is 5% to 30%. [12] Secondary battery according to claim 1, wherein the anode film layer comprises a first film layer and a second film layer arranged between the first film layer and the anode collector, wherein the first film layer comprises a first active anode material which comprises a first graphite material, wherein the I D / I G -ratio of the first graphite material is 0.4 to 0.9; wherein the second film layer comprises a second active anode material which comprises a second graphite material, wherein the I D / I G -ratio of the second graphite material is 0.05 to 0.2; where ID stands for the intensity of the D-peak of the Raman spectrum at 1350±50 cm⁻¹ -1 and IG for the intensity of the G-peak of the Raman spectrum at 1580±50 cm -1 stands. [13] Secondary battery according to claim 12, wherein the first active anode material further comprises an anode coating layer distributed on the surface of the first graphite material, comprising amorphous carbon. [14] Secondary battery according to claim 13, wherein the anode coating layer has a thickness of 10 nm to 100 nm. [15] Secondary battery according to claim 14, wherein the second film layer further comprises a first graphite material. [16] Secondary battery according to claim 15, wherein the mass ratio of the second graphite material to the first graphite material in the second film layer is (3-5):(5-7). [17] Secondary battery according to claim 12, wherein the ratio of the average thickness of the first film layer to the average thickness of the second film layer is (3-5):(5-7). [18] Secondary battery according to claim 12, wherein the anode film layer fulfills at least one of the following: (1) the coating weight of the anode film layer arranged on one side of the anode collector, 80 mg / 1540.25 mm 2 up to 170 mg / 1540.25 mm 2 amounts; (2) the thickness of the anode film layer arranged on one side of the anode collector is 40 µm to 75 µm. [19] Secondary battery according to claim 1, wherein the anode collector has a thickness of 4 µm to 8 µm. [20] Secondary battery according to claim 1, wherein the cathode film layer comprises an active cathode material comprising a first active cathode material, wherein the first active cathode material comprises a lithium-containing phosphate with an olivine structure. [21] Secondary battery according to claim 20, wherein the lithium-containing phosphate with an olivine structure comprises a compound represented by formula (I): LiFe 1-x-y Mn x M 1 y PO4, Formula (I); where in formula (I) M 1 at least one element is from the group consisting of V, Nb, Ti, Co, Ni, Sc, Ge, Mg, Al, Zr, Mn, Hf, Ta, Mo, W, Ru, Ag, Sn and Pb; where 0 ≤ x ≤ 1 and 0 ≤ y < 1. [22] Secondary battery according to claim 20, wherein the first active cathode material further comprises a cathode coating layer arranged on at least a part of the surface of the lithium-containing phosphate, the cathode coating layer comprising at least one of a fast ion conductor material and a carbon material. [23] Secondary battery according to claim 22, wherein the mass ratio of the fast ion conductor material to the carbon material in the cathode coating layer is (0-100):(100-0). [24] Secondary battery according to claim 22, wherein the cathode coating layer comprises a first coating layer and a second coating layer; wherein the first coating layer comprises a fast-ion conductor material and the second coating layer comprises a carbon material; wherein the first coating layer is arranged between the lithium-containing phosphate and the second coating layer; or wherein the second coating layer is arranged between the lithium-containing phosphate and the first coating layer. [25] Secondary battery according to claim 22, wherein the fast ion conductor material comprises a compound represented by formula (II): Li 3-b Fe 2-b M 2 b (PO4)3, Formula (II); where in formula (II) M 2 at least one element is from the group consisting of Ti, Zr, Hf, Ge and Sn, where 0 ≤ b ≤ 1. [26] Secondary battery according to claim 22, wherein the mass fraction of carbon in the first active cathode material is 1% to 1.5%. [27] Secondary battery according to claim 20, wherein the first active cathode material fulfills at least one of the following: (1) the BET-specific surface area of ​​the first active cathode material 12 m 2 / g up to 16 m 2 / g is; (2) the bulk density of the first active cathode material 0.8 g / cm³ 3 up to 1.3 g / cm³ 3 amounts; (3) the volume-averaged particle size Dv50 of the first active cathode material is 1 µm to 3 µm; (4) the density of the first active cathode material at 50,000 N is 2.5 g / cm³ 3 up to 2.6 g / cm³ 3 amounts. [28] Secondary battery according to claim 20, wherein the active cathode material further comprises a second active cathode material comprising a lithium transition metal oxide. [29] Secondary battery according to claim 28, wherein the mass ratio of the first active cathode material to the second active cathode material is (99-90):(1-10). [30] Secondary battery according to claim 20, wherein the cathode film layer fulfills at least one of the following: (1) the thickness of the cathode film layer arranged on one side of the cathode collector is 100 µm to 200 µm; (2) the coating weight of the cathode film layer 200 mg / 1540.25 mm 2 up to 400 mg / 1540.25 mm 2 amounts. [31] Secondary battery according to claim 1, wherein the cathode collector has a thickness of 10 µm to 18 µm. [32] Secondary battery according to claim 1, wherein the cathode film layer further comprises a cathode dispersion agent comprising at least one compound from the group consisting of polyethylene glycol octylphenyl ether, polyvinylpyrrolidone and sodium carboxymethylcellulose. [33] Secondary battery according to claim 32, wherein the mass fraction of the cathode dispersion medium relative to the cathode film layer is 0.3% to 5%. [34] Secondary battery according to claim 1, wherein the secondary battery further comprises an electrolyte solution comprising an electrolyte salt and a solvent; wherein the solvent comprises at least one compound from the group consisting of ethylidene carbonate, propylidene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylenepropyl carbonate, ethylenepropyl carbonate, butylidene carbonate, ethylidene fluorocarbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone; wherein the electrolyte salt comprises at least one compound from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate and lithium tetrafluoro(oxalato)phosphate. [35] Secondary battery according to claim 34, wherein the electrolyte solution further comprises an additive comprising at least one compound from the group consisting of barium sulfate, poly(trifluoroethyl methacrylate), bicyclosulfate, tricyclosulfate, tris(trimethylsilyl) phosphate and vinylene carbonate. [36] Secondary battery according to claim 35, wherein the mass fraction of the additive in the electrolyte solution is 1% to 10%. [37] Secondary battery according to claim 36, wherein the electrical conductivity of the electrolyte solution is 10 mS / cm to 18.5 mS / cm. [38] Power-consuming device comprising a secondary battery according to any one of claims 1 to 37.

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