Battery cell, battery device and power-consuming device

Abstract

Battery cell comprising a stacked electrode assembly and an electrolyte solution, wherein the stacked electrode assembly comprises a cathode foil, a separating film and an anode foil stacked on top of each other, wherein the separating film comprises a base film and coatings arranged on both sides of the base film, wherein the coating comprises an adhesive layer, wherein the adhesive layer is a continuous layer with a porous structure, and wherein the adhesive layer comprises a fluoropolymer; wherein the electrolyte solution comprises a chain carbonate, wherein the mass fraction of the chain carbonate is 43% to 71% relative to the total mass of the electrolyte solution.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] The present disclosure is based on a Chinese patent application with application number 202510830566.5, the filing date of June 20, 2025 and the title "Battery cell, battery device and power-consuming device" and claims its priority; the entire content is hereby incorporated into the present disclosure by reference. TECHNICAL AREA

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

[0003] As the range of applications for secondary batteries has expanded considerably in recent years, they are now used in numerous sectors, including energy storage systems such as hydroelectric, thermal, wind, and solar power plants, as well as in many other applications like power tools, e-bikes, e-motorcycles, electric vehicles, and aerospace. Among these many applications, there has always been a strong consumer market demand for miniaturized batteries with high capacity and long lifespans.

[0004] With the increasing prevalence and rapid development of secondary batteries, the requirements for their energy density and cycle performance have increased. CONTENT OF THE PRESENT INVENTION

[0005] The present disclosure is made with regard to the above-mentioned problems and aims to provide a battery cell, a battery device and a power-consuming device, wherein the battery cell has a stable battery cell structure and can establish a balance between energy density and cycle power.

[0006] To achieve the aforementioned objectives, the first aspect of this disclosure provides a battery cell. The battery cell comprises a stacked electrode assembly and an electrolyte solution, wherein the stacked electrode assembly comprises a cathode foil, a separator film, and an anode foil stacked one above the other; the separator film comprises a base film and coatings arranged on both sides of the base film, the coatings comprising an adhesive layer, the adhesive layer being a continuous layer with a porous structure, and the adhesive layer comprising a fluoropolymer; wherein the electrolyte solution comprises a chain carbonate, the mass fraction of the chain carbonate being 43% to 71% of the total mass of the electrolyte solution.

[0007] The battery cell utilizes a stacked electrode array to achieve high energy density and employs a separating film with adhesive layers on both sides. These adhesive layers comprise a fluoropolymer and form a continuous layer with a porous structure. This results in improved adhesion between the electrode foil and the separating film, thus yielding a battery cell with high energy density and a stable structure. The chain carbonate used as a solvent for anhydrous electrolyte solution exhibits a lower viscosity than cyclic carbonate. When the electrolyte solution contains a chain carbonate with a mass fraction of 43% to 71%, the viscosity of the electrolyte solution is effectively reduced, improving the wetting of the electrode array. Therefore, the battery cell described in this disclosure not only exhibits a stable structure but also offers high energy density and cycle performance.

[0008] In some embodiments, the mass fraction of the chain carbonate is specified as being between 52% and 62% of the total mass of the electrolyte solution. This results in improved wettability of the electrode arrangement.

[0009] In some embodiments, the chain carbonate comprises dimethyl carbonate and / or ethyl methyl carbonate. When DMC and EMC are used in combination, the viscosity of the electrolyte solution can be effectively reduced and its wettability improved without impairing the battery's performance at low temperatures.

[0010] In some embodiments, the electrolyte solution also includes cyclic carbonate. Cyclic carbonate facilitates the dissociation of lithium salts and improves the electrical conductivity of the electrolyte solution. Furthermore, cyclic carbonate can form a stable SEI film on the anode surface, which positively impacts the battery's cycle stability and safety.

[0011] In some embodiments, the mass fraction of cyclic carbonate is specified as being between 14% and 42% of the total mass of the electrolyte solution. If the mass fraction of cyclic carbonate is within the aforementioned range, this is advantageous for improving the electrical conductivity of the electrolyte solution without impairing the wettability of the electrode arrangement by the electrolyte solution.

[0012] In some embodiments, the fluoropolymer is provided to comprise one or more of polyvinylidene fluoride, vinylidene fluoride-trifluorochloroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluorochloroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer and vinylidene fluoride-trifluorochloroethylene-tetrafluoroethylene-hexafluoropropylene copolymer.

[0013] This polymer is soluble in the oil-based solvent, allowing the molecular chains to open and form a relatively uniform slurry. This creates a continuous film structure during application, significantly improving adhesion to the electrode foil.

[0014] In some embodiments, the adhesive layer has a thickness of 0.15 µm to 2 µm on one side. Within this thickness range, the adhesive strength between the separating film and the electrode foil is suitable without impairing the transport of lithium ions, which has a positive effect on the cycle performance and safety of the battery cell.

[0015] In some embodiments, the coating also includes a ceramic layer positioned between the base film and the adhesive layer. By incorporating a ceramic layer between the base film and the adhesive layer, the wettability of the separator by the electrolyte solution can be improved, the flow of the electrolyte solution promoted, and the performance degradation of the battery cell caused by insufficient electrolyte solution wetting further reduced, thereby improving the cycle performance of the battery cell.

[0016] In some embodiments, the ceramic layer is provided to comprise one or more of aluminium oxide, boehmite, silicon dioxide, magnesium oxide, titanium oxide, tin oxide, calcium oxide, zirconium oxide, yttrium oxide, zinc oxide, silicon carbide, magnesium fluoride, barium sulfate, barium titanate, aluminium hydroxide, magnesium hydroxide and calcium hydroxide.

[0017] In some embodiments, the thickness of the ceramic layer on one side is 0.5 to 4 µm. Within this thickness range, the wettability and fluid retention of the electrolyte solution can be improved, which has a positive effect on the cycle performance and safety of the battery cell.

[0018] In some embodiments, the thickness of the base film is provided for to be 7 µm to 9 µm.

[0019] In some embodiments, the cathode foil comprises a cathode current collector and a cathode film layer arranged on at least one side of the cathode current collector, wherein the cathode film layer comprises an active cathode material, the active cathode material comprises particles of lithium-containing transition metal phosphate, wherein the particles of lithium-containing transition metal phosphate comprise a matrix of lithium-containing transition metal phosphate and an encapsulating layer located on at least a part of the surface of the matrix of lithium-containing transition metal phosphate, the encapsulating layer comprising the carbon element, wherein the chemical formula of the lithium-containing transition metal phosphate matrix is ​​as follows: Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 0.8, 0.9 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; where A comprises one or more of Na, K, and Mg; where Me comprises one or more of Mn, Fe, Co, and Ni; where M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; where X comprises one or more of S, Si, Cl, B, C, N and P; where Y comprises one or more of O and F.

[0020] In some embodiments, the lithium-containing transition metal phosphate comprises lithium iron phosphate.

[0021] The active cathode material made of lithium and iron exhibits good cycle performance and high safety, but its gram capacity is relatively low. By arranging the electrodes in a stacked configuration, the energy density of lithium-iron battery cells can be effectively improved.

[0022] In some embodiments, the lithium-containing transition metal phosphate contains the element Ti, with the mass fraction of the element Ti being between 0.05% and 0.2% relative to the mass of the lithium-containing transition metal phosphate. In lithium-containing transition metal phosphate, the element Ti can lower the transport barrier for lithium ions and increase the diffusion rate of the lithium ions, thereby improving the dynamic properties and cycle performance of the battery.

[0023] In some embodiments, it is provided that D A50 the particle size of the lithium-containing transition metal phosphate in the cumulative area distribution curve of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 70 nm to 3 µm, where D A50represents the particle size value that corresponds to a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the particle size. D A50 The active cathode material can, on the one hand, shorten the diffusion path of the lithium ions and, on the other hand, reduce the expansion and contraction of the particle volume caused by the insertion and removal of lithium ions; this, in combination with the binding effect of the adhesive layer, improves the structural stability of the stack and thus the overall cycle performance.

[0024] In some embodiments, it is provided that the sphericity L A50 in the cumulative area distribution curve of the sphericity of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 0.70 to 0.75, where L A50The sphericity is represented by a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the sphericity. Within a certain range, the L indicates A50 of particles of the lithium-containing transition metal phosphate indicates that a relative slip between the particles is more likely, whereby the internal stress of the electrode foil is reduced by slip, thereby reducing the damage to the electrode foil structure caused by the stress reduction of the electrode foil and improving battery performance.

[0025] In some embodiments, the porosity of the cathode film is specified as being between 23% and 32%. The cathode film layer exhibits a certain porosity that simultaneously ensures high density and good wetting, thus guaranteeing that the battery cell has a high energy density and good cycle performance.

[0026] In some embodiments, the density of the cathode foil is specified as 2.25 g / cm³. 3 up to 2.65g / cm³ 3 amounts.

[0027] In some embodiments, the density of the cathode foil is provided for to be 2.3 g / cm³. 3 up to 2.45g / cm³ 3 amounts.

[0028] The compression density of the cathode foil, which lies within the aforementioned range, enables the battery cell to achieve a high energy density while simultaneously ensuring wetting with the electrolyte solution and the cycle performance of the battery.

[0029] In some embodiments, the one-sided coating weight of the cathode film layer is 0.33g / 1540.25 mm². 2 up to 0.43g / 1540.25 mm 2 amounts.

[0030] In some embodiments, the one-sided coating weight of the cathode film layer is 0.36g / 1540.25 mm². 2up to 0.40g / 1540.25 mm 2 amounts.

[0031] If the one-sided coating weight of the cathode film layer is within a suitable range, the battery cell can have a high energy density and is conducive to ion transport.

[0032] In some embodiments, the anode foil comprises an anode current collector and an anode film layer arranged on at least one side of the anode current collector, and the porosity of the anode foil is 23% to 32%.

[0033] Within this area, the porosity of the anode film layer can simultaneously ensure a high compaction density and good wetting, thus guaranteeing that the battery cell has a high energy density and good cycle performance.

[0034] In some embodiments, the compression density of the anode foil is specified as 1.3 g / cm³. 3 up to 1.55g / cm³ 3amounts.

[0035] In some embodiments, the compression density of the anode foil is provided for to be 1.4 g / cm³. 3 up to 1.5g / cm³ 3 amounts.

[0036] The compression density of the anode foil, which lies within the aforementioned range, enables the battery cell to achieve a high energy density while simultaneously ensuring wetting with the electrolyte solution and the cycle performance of the battery.

[0037] In some embodiments, the one-sided coating weight of the anode film layer is 0.15g / 1540.25 mm². 2 up to 0.207g / 1540.25 mm 2 amounts.

[0038] In some embodiments, the one-sided coating weight of the anode film layer is 0.17g / 1540.25 mm². 2 up to 0.2g / 1540.25 mm 2 amounts.

[0039] If the one-sided coating weight of the anode film layer is within a suitable range, the battery cell can have a high energy density and is conducive to ion transport.

[0040] In some embodiments, the anode foil comprises an anode film layer, wherein the anode foil comprises an active anode material comprising graphite with a particle size Dv50 of 13 µm to 22 µm.

[0041] In some embodiments, the particle size Dv50 of the graphite is provided to be between 14.5 µm and 20 µm.

[0042] The use of graphite with a larger particle size (Dv50) within the aforementioned range is advantageous for increasing the compaction density of the electrode foil and thus for increasing the volume energy density of the battery. The electrolyte solution, which contains a certain amount of chain carbonate as a solvent, exhibits good flow properties, effectively improving the wetting of the anode foil and thus increasing the volume energy density of the battery, taking cycle performance into account.

[0043] In some embodiments, the porosity of the separating film is provided for to be between 28% and 50%.

[0044] In some embodiments, the porosity of the separating film is provided to be between 31% and 40%.

[0045] The porosity of the base film within the above-mentioned area is conducive to the passage of active ions.

[0046] A second aspect of the present disclosure relates to a battery device comprising the previously mentioned battery cell.

[0047] A third aspect of the present disclosure provides a power-consuming device comprising the previously mentioned battery device. The battery device and power-consuming device of the present disclosure also possess the advantages mentioned above because they contain battery cells. BRIEF DESCRIPTION OF THE DRAWING Fig. Figure 1 is a schematic representation of the microstructure of the surface of the separating film described in this disclosure; Fig. Figure 2 is a schematic representation of the microstructure of the surface of the traditional release film; Fig. Figure 3 is a schematic representation of a battery cell according to an embodiment of the present disclosure; Fig.Figure 4 is an exploded view of a battery cell according to an embodiment of the present disclosure, which is in Fig. 3 is shown; Fig. Figure 5 is a schematic representation of a battery module according to an embodiment of the present disclosure; Fig. Figure 6 is a schematic representation of a battery pack according to an embodiment of the present disclosure; Fig. Figure 7 is an exploded view of a battery pack according to an embodiment of the present disclosure, which is shown in Fig. 6 is shown; Fig. Figure 8 is a schematic representation of a power-consuming device which, according to one embodiment of the present disclosure, uses the secondary battery as a power source. Reference symbol list:

[0048] 10 Separating film of the present disclosure; 11 Porous continuous adhesive layer; 111 Pore; 12 Ceramic layer; 20 Conventional separating film; 21 Island-like adhesive; 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover assembly. DETAILED DESCRIPTION

[0049] In the following, embodiments of the lithium-ion secondary battery and the power-consuming device of the present disclosure are described in detail with reference to the accompanying drawings. However, an unnecessarily detailed description can be omitted. For example, a detailed description of known facts and a repeated description of essentially the same structure can be omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding by the person skilled in the art. Furthermore, the drawings and the following description serve to provide the person skilled in the art with a complete understanding of the present disclosure and are not intended to limit the subject matter of the present disclosure.

[0050] The “ranges” disclosed in this disclosure are defined in terms of a lower limit and an upper limit. A particular range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of that range. The range thus defined may include or exclude the end values ​​and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also considered. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, all of the following ranges are anticipated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.In this disclosure, unless otherwise specified, the number range "ab" represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the number range "0 to 5" means that all real numbers between "0 to 5" are listed in this article, and "0 to 5" is simply an abbreviation for these number combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or the like.

[0051] Unless otherwise stated, all embodiments and optional embodiments of the present disclosure can be combined to form a new technical solution.

[0052] Unless otherwise stated, all technical features and optional technical features of this disclosure can be combined to form a new technical solution.

[0053] Unless otherwise specified, all steps of this disclosure may be carried out sequentially or in any order, but preferably sequentially. For example, if a process includes steps (a) and (b), this means that the process may include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. For example, the said process may also include step (c), which means that step (c) may be inserted into the process in any order; for example, the process may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), and the like.

[0054] Unless otherwise stated, the terms used in this disclosure have the general meanings which are generally known to those skilled in the art in this field.

[0055] Unless otherwise stated, the values ​​of the parameters mentioned in this disclosure can be determined using various test procedures commonly used in this field, for example, according to the test procedures specified in this disclosure.

[0056] Currently, the market is increasingly demanding higher capacities and longer lifespans for secondary batteries. One solution with current technology is to use a stacked electrode arrangement to improve the energy density of the battery cell. A stacked structure is formed by layering the cathode foil, separator film, and anode foil in that order, with the cathode foil and anode foil separated by the separator film. However, during the battery manufacturing process, shifting and misalignment between the electrode foils can easily occur.During battery cycling, the adhesion between the electrode foil interfaces is weak due to the parallel arrangement of the electrode foils in the stacked battery cell, and the volume expansion during charging and discharging can lead to separation of the intermediate layers. This poses various safety risks, such as lithium precipitation. To improve the safety of stacked batteries, a separating film with adhesive layers on both sides is proposed. The adhesive layer strengthens the adhesion between the separating film and the electrode, thereby stabilizing the battery cell structure.

[0057] However, studies have shown that when using the separating film with an adhesive layer in a stacked electrode arrangement, either the adhesion is not strong enough and electrode misalignment and lithium precipitation still occur during use, or the cycle performance of a secondary battery with good adhesion is not optimal.

[0058] Based on this, the present disclosure provides a battery cell, a battery device, and a power-consuming device. The battery cell has a stable cell structure and also takes cycle performance into account. The present disclosure and its alternative embodiments are described in more detail below. Battery cell

[0059] The first aspect of the present disclosure is the provision of a battery cell. The battery cell comprises a stacked electrode arrangement and an electrolyte solution, wherein the stacked electrode arrangement comprises a cathode foil, a separator film, and an anode foil stacked one on top of the other; the separator film comprises a base film and coatings arranged on both sides of the base film, the coatings comprising an adhesive layer, the adhesive layer being a continuous layer with a porous structure, and the adhesive layer comprising a fluoropolymer; wherein the electrolyte solution comprises a chain carbonate as a solvent, the mass fraction of the chain carbonate as solvent being 43% to 71% based on the total mass of the electrolyte solution.

[0060] The adhesive layer used in this disclosure is a porous continuous layer structure, primarily produced from an oil-based adhesive, i.e., by dispersing the adhesive with an organic solvent and subsequently coating it into a film. The adhesive layer thus formed is a continuous structure (with reference to Fig. 1, which schematically shows the microstructure of the surface of the release film 10 of the present disclosure). This structure differs from the adhesive layer produced from the conventional water-based adhesive, where the adhesive is mainly dispersed in an aqueous solvent and then applied to form a film, so that the adhesive layer formed has an island structure (with reference to Fig.Figure 2, which schematically shows the microstructure of the surface of the separating film 20 formed with a conventional water-based adhesive.) While the adhesive layer of the island structure is easy to produce, it has a small adhesive area and low adhesion. This problem is particularly evident in the stacked battery, where it can lead to misalignment of the electrode foil of the stacked battery and thus impair cycle performance. Therefore, the battery cell of the present invention uses a stacked electrode arrangement and simultaneously employs a separating film with a continuous adhesive layer that has the aforementioned porous structure on both sides. This achieves good adhesion between the electrode foil and the separating film, resulting in a battery cell with high energy density and a stable battery cell structure.On the one hand, the continuous film layer allows for a larger contact area between the adhesive layer and the electrode foil, thereby improving the adhesion between the separating film and the electrode foil; on the other hand, the porous structure facilitates the transport of active ions in the electrolyte solution between the separating films.

[0061] As previously reported, studies have shown that even when using this separating film with good adhesion, the battery's cycle life is not optimal and lithium precipitation continues to occur. Further investigations revealed that the aforementioned phenomenon is due to the fact that a large adhesive area between the electrode foil and the separating film, combined with strong adhesion, impairs the wetting of the electrode array by the electrolyte solution, leading to insufficient local wetting and thus reducing the battery's cycle life.

[0062] Therefore, the present disclosure proposes using a chain carbonate as a solvent with the aforementioned mass fraction range in the electrolyte solution of the battery cell. As a solvent for anhydrous electrolyte solution, the chain carbonate exhibits a lower viscosity than cyclic carbonate. In an electrolyte solution with a cyclic carbonate content of 43% to 71%, the viscosity of the electrolyte solution is effectively reduced, and the wetting of the electrode assembly by the electrolyte solution is improved. Therefore, the battery cell of the present disclosure not only exhibits a stable battery cell structure but also offers improved energy density and cycle performance.

[0063] The morphology of the continuous layer of the porous adhesive structure on both sides of the separator film can be observed using an electron microscope. For example, the separator film can be removed from a battery cell, the surface cleaned, and then observed, for example, under a scanning electron microscope. To reflect the true morphology of the separator film, the sampling process preferably focuses on the area where the adhesive layer of the separator film is not bonded to the cathode or anode foil within the battery. For example, samples are taken from the position of the separator film where the projection extends beyond the cathode and anode foils; alternatively, sampling can be performed on the separator near the surface of the electrode assembly. These sampling areas exhibit lower adhesion between the separator film and the cathode or anode foil, respectively.the anode foil and thus better reflect the true condition of the separating film.

[0064] Furthermore, it is understood that the continuous structure can become blocky through contact with the cathode foil or the anode foil, or through compression during the manufacture of the electrode foil or the cycling process. The continuous structure mentioned in this disclosure does not mean that the adhesive layer is continuous across the entire battery. Rather, it refers to a microscopic level where—as observed under an electron microscope—a network-like continuous layer with a porous structure is present, instead of an island structure.

[0065] The battery cell described in this revelation will be explained in more detail below. electrolyte solution

[0066] The electrolyte solution in the battery cell of the present disclosure comprises an electrolyte salt and an organic solvent. As previously stated, the electrolyte solution comprises a chain carbonate as a solvent in a mass fraction of 43% to 71%. For example, the mass fraction of the chain carbonate as solvent, based on the total mass of the electrolyte solution, is any value of 43%, 45%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 65%, 70%, 71%, or a value within a range formed by any two of these values. Optionally, the mass fraction of the chain carbonate as solvent, based on the total mass of the electrolyte solution, is 52% to 62%.

[0067] In some embodiments, the chain carbonate comprises dimethyl carbonate (DMC) and / or ethyl methyl carbonate (EMC) as solvents. Optionally, the chain carbonate can comprise both DMC and EMC as solvents. Furthermore, the chain carbonate can optionally contain both DMC and EMC.

[0068] DMC has a lower viscosity than EMC and can therefore play a greater role in reducing the viscosity of the electrolyte solution. However, DMC has a relatively high crystallization temperature, which is why its performance at low temperatures is relatively poor and it tends to crystallize at low temperatures. When DMC and EMC are used in combination, the viscosity of the electrolyte solution can be effectively reduced and its wettability improved without compromising battery performance at low temperatures.

[0069] The present disclosure does not specify any particular restrictions on the ratio of DMC to EMC, which can be adjusted as required. In some embodiments, the mass fraction of DMC is provided to be 8% to 43%, based on the total mass of the electrolyte solution. For example, the mass fraction of DMC, based on the total mass of the electrolyte solution, can be any value of 8%, 10%, 12%, 15%, 17%, 20%, 12%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 43%, or a value within a range formed by any two of these values. Optionally, the mass fraction of DMC, based on the total mass of the electrolyte solution, can be 20% to 35%. If the DMC content in the electrolyte solution is within the range mentioned above, it can fully exert its effect of reducing the viscosity of the electrolyte solution without affecting the low-temperature performance of the battery.

[0070] In other embodiments, the chain carbonate can also comprise diethyl carbonate DEC.

[0071] In some embodiments, the organic solvent also includes a cyclic carbonate. Cyclic carbonate facilitates the dissociation of lithium salts and improves the electrical conductivity of the electrolyte solution. Furthermore, cyclic carbonate can form a stable SEI film on the anode surface, which positively impacts the battery's cycle stability and safety.

[0072] In some embodiments, the cyclic carbonate may comprise ethylene carbonate (EC) and / or propylene carbonate (PC).

[0073] In some embodiments, the mass fraction of cyclic carbonate, based on the total mass of the electrolyte solution, is provided to be between 14% and 42%. For example, the mass fraction of cyclic carbonate, based on the total mass of the electrolyte solution, can be any value of 14%, 17%, 20%, 23%, 24%, 26%, 28%, 30%, 32%, 33%, 36%, 39%, 42%, or a value within any range formed by any two of these values. Optionally, the mass fraction of cyclic carbonate, based on the total mass of the electrolyte solution, is between 23% and 33%. Having the mass fraction of cyclic carbonate within the aforementioned range is advantageous for improving the electrical conductivity of the electrolyte solution without impairing the wettability of the electrode assembly by the electrolyte solution.

[0074] In some embodiments, the solvent may also comprise one or more of dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0075] In some embodiments, the mass fraction of organic solvent, based on the total mass of the electrolyte solution, is provided to be 82% to 92%, optionally 84% to 89%. For example, the mass fraction of the solvent in the electrolyte solution can be any value of 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, or a value within a range formed by any two of these values.

[0076] The present disclosure does not specify any particular limitations for the electrolyte salt. In some embodiments, the electrolyte salt comprises a lithium salt. The lithium salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorobisoxalatophosphate, and lithium tetrafluorooxalate phosphate. Optionally, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, and lithium bis(fluorosulfonyl)imide.

[0077] In some embodiments, the mass fraction of the electrolyte salt, based on the total mass of the electrolyte solution, is 8% to 18%, optionally 11% to 15%.

[0078] In some embodiments, the electrolyte solution may also include an additive. The additive may, for example, form the anode film, form the cathode film, or enhance certain battery properties, such as improving the battery's overcharge performance, high-temperature or low-temperature performance, or the like. For example, the additive may include one or more of vinylene carbonate, fluoroethylene carbonate, and fluorobenzene. The mass fraction of the additive, based on the total mass of the electrolyte solution, is 0.4% to 5%, optionally 0.7% to 3%.For example, the mass fraction of the additive in the electrolyte solution is any value from 0.5%, 0.7%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% to 5% or a value within a range formed by any two of these values.

[0079] In this disclosure, the type and content of organic components in the electrolyte solution can be determined using equipment and methods known in this field. For example, the organic components in the electrolyte solution can be analyzed qualitatively and quantitatively by gas chromatography with reference to GB / T9722-2006 "General rules for the gas chromatography of chemical reagents". In the embodiments of this disclosure, freshly prepared electrolyte solution can be used as a sample, or the free electrolyte solution from a new battery can be used as a sample, or the already discharged battery (it is discharged to the lower limit of the reverse voltage, so that the state of charge of the battery is approximately 0% SOC) is disassembled in reverse order, and the free electrolyte solution obtained from the battery is taken as a sample and determined by the gas chromatography analysis method.

[0080] In the present disclosure, the types and concentrations of the inorganic components / lithium salt concentration in the electrolyte solution are well known in this field and can be determined using equipment and methods well known in this field; for example, reference can be made to the standard JY / T020 - 1996 "General requirements for the ion chromatography analysis method" to qualitatively or quantitatively analyze the inorganic components / lithium salt concentration in the electrolyte solution by applying the ion chromatography analysis method.In the embodiments of the present disclosure, freshly prepared electrolyte solution can be used as a sample, or the free electrolyte solution from a new battery can be used as a sample, or the already discharged battery (it is discharged to the lower limit of the reverse voltage, so that the state of charge of the battery is approximately 0% SOC) is disassembled in reverse direction, the free electrolyte solution obtained from the battery is taken as a sample and detected using the ion chromatography analysis method. Release film

[0081] As already mentioned, the separating film of the present disclosure comprises a base film and coatings arranged on both sides of the base film, the coatings comprising an adhesive layer.

[0082] The present disclosure is not subject to any particular restrictions regarding the type of base film, and any known base film with a porous structure and good chemical and mechanical stability may be selected. In some embodiments, the base film material comprises one or more glass fibers, nonwoven fabrics, polyethylene, polypropylene, and polyvinylidene fluoride. The base film may, without particular restriction, be a single-layer membrane or a multilayer composite membrane. If the base film is a multilayer composite membrane, the materials of the individual layers may be the same or different without particular restriction. Optionally, the base film may be made of polyethylene.

[0083] In some embodiments, the thickness of the base film is specified as being between 7 µm and 9 µm; this thickness range has a positive effect on the safety performance of the battery cell. For example, the thickness of the base film can be any value of 7 µm, 8 µm, and 9 µm, or a value within a range formed by any two of these values.

[0084] The coating is located on both sides of the base film and comprises an adhesive layer that forms a continuous layer with a porous structure. In some embodiments, the adhesive layer is applied to the surface of the base film and is in contact with it. In other embodiments, further intermediate layers, such as a ceramic layer, are located between the adhesive layer and the base film, as described in more detail below.

[0085] The adhesive layer comprises a fluoropolymer. Specifically, the fluoropolymer comprises one or more of the following: polyvinylidene fluoride, vinylidene fluoride-trifluorochloroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluorochloroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride-trifluorochloroethylene-tetrafluoroethylene-hexafluoropropylene copolymer. Optionally, the fluoropolymer also comprises polyvinylidene fluoride (PVDF).

[0086] The present disclosure does not specify any particular restrictions for a specific fluoropolymer; commercially available fluoropolymers may be used, in particular those suitable as adhesives, but are not limited to them.

[0087] This type of polymer exhibits different solubilities in water-based and oil-based solvents. Typically, the fluoropolymer is insoluble in aqueous solvents and disperses as particles, but it can dissolve in oil-based solvents, where the molecular chains open and form a more uniform slurry. This results in the formation of a uniform film layer during application, rather than a discrete, dot-like distribution. Furthermore, the addition of a pore-forming agent can create a non-uniform porous structure in the coating, which significantly improves adhesion to the electrode foil and allows active ions in the electrolyte solution to be transported through these pores on both sides of the separating film.

[0088] In the porous structure of the adhesive layer of the present disclosure, the pore size is typically less than 15 micrometers, and in terms of the area unit, the area fraction of the pore is 15% to 50%.

[0089] In some embodiments, the thickness of the adhesive layer on one side is between 0.15 µm and 2 µm. Within this thickness range, the adhesive strength between the separating film and the electrode foil is within a suitable range, which has a positive effect on the cycle life and safety performance of the battery cell. For example, the thickness of the adhesive layer on one side can be any value of 0.15 µm, 0.8 µm, 1 µm, 1.2 µm, 1.4 µm, 1.5 µm, 1.6 µm, 1.8 µm, or 2 µm, or any value within a range formed by any two of these values.

[0090] Therefore, the “one-sided thickness of the adhesive layer” mentioned in this revelation refers to the average thickness of the film layer of the adhesive material, without including the pores in the film layer where no adhesive material is located.

[0091] In some embodiments, the coating on both sides of the base film also includes a ceramic layer arranged between the base film and the adhesive layer.

[0092] The ceramic layer comprises one or more of the following: aluminum oxide, boehmite, silicon dioxide, magnesium oxide, titanium oxide, tin oxide, calcium oxide, zirconium oxide, barium sulfate, yttrium oxide, zinc oxide, silicon carbide, magnesium fluoride, barium titanate, aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. Optionally, the ceramic layer may include aluminum oxide and / or boehmite.

[0093] The ceramic layer exhibits good wetting properties for the electrolyte solution. During the cycling process, the ceramic layer can promote the wetting of the separator film surface with the electrolyte solution and improve the separator film's electrolyte retention capacity. By incorporating a ceramic layer between the base film and the adhesive layer, the wettability of the separator film by the electrolyte solution can be improved, the flow of the electrolyte solution promoted, and the interfacial problems of the electrode assembly caused by insufficient electrolyte wetting further reduced, thus contributing to improved cycle performance of the battery cells. In some embodiments, the average particle size of the ceramic material is between 0.2 µm and 2.5 µm; optionally between 0.5 µm and 1.5 µm.Controlling the average particle size of the ceramic material within the aforementioned range is advantageous for improving the electrolyte solution retention capacity of the separating film, which in turn further improves lithium precipitation and thus increases the cycle life and safety performance of the battery cells. For example, the average particle size of the ceramic material can be any value of 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 2.5 µm, or a value within any range formed by any two of these values.

[0094] In addition to ceramic particles, the ceramic layer also comprises an adhesive. In some embodiments, the mass ratio of ceramic particles to adhesive is (3:1) to (10:1); optionally 5:1. The present disclosure does not impose any particular restrictions regarding the type of adhesive, which may also be a fluoropolymer, such as one or more of polyvinylidene fluoride, vinylidene fluoride-trifluorochloroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluorochloroethylene-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride-trifluorochloroethylene-tetrafluoroethylene-hexafluoropropylene copolymer. Optionally, the adhesive comprises polyvinylidene fluoride (PVDF).

[0095] The above adhesive, in a specific mass ratio, can distribute the ceramic particles so evenly and densely that a film layer is formed; furthermore, it also contributes to the close bond between the base film, the ceramic layer, and the adhesive layer.

[0096] The ceramic layer may also optionally include a thickening agent. The thickening agent helps to ensure that the slurry used to coat the ceramic layer is uniform and stable, thus facilitating the formation of a uniform ceramic layer. This disclosure does not impose any specific restrictions regarding the types of thickening agent. The thickening agent may, for example, comprise at least one of hydroxyethylcellulose, methylhydroxyethylcellulose, sodium carboxymethylcellulose, polyacrylamide, or sodium alginate. This disclosure does not impose any specific restrictions regarding the thickening agent content in the oil-based adhesive layer; those skilled in the art may choose the content as required.

[0097] In some embodiments, the thickness of the ceramic layer on one side is 0.5 to 4 µm. Within this thickness range, the wettability and fluid retention of the electrolyte solution can be improved, which has a positive effect on the cycle life and safety of the battery cell. For example, the thickness of the ceramic layer on one side can be any value of 0.5 µm, 1 µm, 1.5 µm, 2 µm, 2.5 µm, 3 µm, 3.5 µm, or 4 µm, or any value within a range formed by any two of these values.

[0098] The presence of the adhesive layer and the optional ceramic layer in the separating film, which is located away from the electrode assembly, can be observed under a scanning electron microscope (SEM).

[0099] To accurately reflect the separator's morphology, sampling preferably focuses on the area where the adhesive layer of the separator is not bonded to the cathode or anode foil within the battery. For example, samples are taken from the point on the separator where the projection extends beyond the cathode and anode foils. Alternatively, sampling can be performed on the separator near the surface of the electrode assembly. The sampling area of ​​such a separator adheres less to the cathode or anode foil and can thus better reflect the separator's actual condition.

[0100] The specific method for determining the coating thickness can be as follows: a cross-section of the separating film is observed in the thickness direction. Furthermore, the coating morphology can also be observed from the surface of the separating film using a scanning electron microscope (SEM). As before, after removing the separating film from the battery cell and taking a sample from a suitable area, the surface of the separating film sample is cleaned and can be observed using SEM. Referring to the schematic representation of the microstructure of the separating film surface in Fig.Figure 1 shows the surface of the release film 10 according to the present disclosure, showing that the morphology of the porous continuous adhesive layer 11 is a continuous film layer with a porous structure containing multiple pores 111. If a ceramic layer is present, ceramic particles in the ceramic layer 12 below the adhesive layer can be observed through the pores 111 of the adhesive layer 11. In contrast to the release film of the present disclosure, Fig. 2 A schematic representation of the microstructure of the surface of a conventional release film 20 produced by a conventional coating process of the water-based adhesive. With reference to Fig. 2, the surface of the conventional release film 20 also has a ceramic layer 12 on which an island-like adhesive 21 is located. If Fig. 1 with Fig.When compared to 2, it is evident that the adhesive layer of the present disclosure has a comparatively much larger adhesive area.

[0101] In the embodiment of the present disclosure, the thickness of the base film, the thickness of the adhesive layer on one side, and the thickness of the ceramic layer on one side have the meanings customary in this field. The thickness of the base film and the coating in the separator film can be determined using methods and equipment known in this field. For example, a freshly produced separator film can be used as a sample, or the already discharged battery cell (it is discharged to the lower limit of the reverse voltage, so that the state of charge of the battery is approximately 0% SOC) is disassembled in reverse order, the separator film is extracted from the battery cell, and after drying, it is taken as a sample. The separator film is cut in the thickness direction using an ion beam cutter to expose the cut surface, and then the thickness of the cut surface of the separator film and its respective layers is measured using a scanning electron microscope.By adjusting the microscope to a suitable magnification, the base film, ceramic layer, and adhesive layer of the release film can be fully examined, and a mapping test can then be performed on the release film. In the test results, the coating in which the metal elements are distributed is the ceramic layer, and the coating with a high content of carbon and fluorine is the adhesive layer. The thickness T1 of the ceramic coating and the thickness t1 of the adhesive layer are then measured on one side of the base film. Following the steps described above, the thicknesses of the ceramic layer, T2, T3, T4, and T5, are tested in four further different fields of view; and the thicknesses of the organic coating are tested as t2, t3, t4, and t5. The average value is calculated in each case, and this yields the thickness of the ceramic coating and the adhesive layer.

[0102] The specific materials of the adhesive layer and the optional ceramic layer can be tested using the following method: For a separator film taken from the electrode assembly of a battery cell with 0% state of charge (SOC), the separator film, if only the adhesive layer is present, can be dissolved in a suitable solvent (e.g., N-methylpyrrolidone, NMP) before testing using infrared spectroscopy. Alternatively, the entire surface of the separator film sample can be directly tested using infrared spectroscopy, whereby the type of adhesive layer material is identified by detecting characteristic peaks in the infrared spectrum. For a separator film containing both an adhesive layer and a ceramic layer, the separator film can be dissolved in a suitable solvent (e.g., N-methylpyrrolidone, NMP).The release film is treated with NMP and ultrasonically for 60 minutes at 60 °C to remove the coating. Solid samples are then collected and subjected to X-ray diffraction, with the type of ceramic material determined from the XRD pattern. Alternatively, the release film can be immersed in a suitable solvent (e.g., NMP) to dissolve the adhesive layer and subsequently tested by infrared spectroscopy. The entire surface of the release film sample can also be directly tested with an infrared spectrometer, allowing the type of adhesive layer material to be identified by the characteristic peaks in the infrared spectrum.

[0103] In some embodiments, the porosity of the separating film is specified as being between 28% and 50%. A porosity within this range is conducive to the passage of active ions. For example, the porosity of the separating film can be any value of 28%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 45%, 50%, or any value within a range formed by any two of these values. Optionally, the porosity of the separating film can be between 31% and 40%.

[0104] In this disclosure, porosity refers to the percentage of the pore volume in the separating film relative to the total volume of the separating film. The porosity can be tested according to standard GB / T 24586-2009. The separating film can be obtained, for example, by dissecting a battery cell at 0% state of charge (SOC) as described above. It is then cut into 3 mm × 3 mm pieces, and the apparent volume V0 of the sample (the apparent volume of the sample corresponds to the thickness of the cathode film layer multiplied by the area of ​​the sample) is measured. The actual volume of the sample can then be tested using a real density meter. Specifically, the sample is placed in the sample test chamber, nitrogen gas is introduced into the sample test chamber, and the sample test chamber is connected to the reference chamber. The pressure after stabilization is then recorded.The pressure in the reference chamber before and after connection with the sample chamber is measured. Subsequently, the porosity volume is calculated according to Bohr's law PV = nRT, where the sample porosity is calculated as porosity volume / apparent volume. It should be noted that in the actual test process, due to differences in measuring instruments, test errors, and to minimize the impact on the porosity measurement, a measurement process with slight deviations from the standard may be used to obtain more accurate readings.

[0105] The release film of the present invention can be produced without limitation by the following method: dissolving an adhesive and a pore-forming agent in an organic solvent to obtain an adhesive solution; applying the adhesive solution to the porous base film and removing the pore-forming agent after drying to form an adhesive layer on the porous base film.

[0106] The present disclosure does not specify any particular restrictions on the manufacturing process of the release film; it can, for example, be manufactured according to the following process.

[0107] The release film with the ceramic layer is first coated with the ceramic layer. Ceramic particles forming the ceramic layer and an adhesive (e.g., in a mass ratio of 5:1 and optionally a thickening agent) are dispersed in a solvent (e.g., N-methylpyrrolidone, NMP) to form a ceramic layer slurry. This ceramic layer slurry is applied to both sides of a base film. After drying to remove the solvent, a release film with ceramic layers on both sides of the base film is obtained.

[0108] Next, the adhesive layer is applied. A fluoropolymer (e.g., PVDF, with a final mass fraction of 20%) is dissolved in an organic solvent (e.g., NMP), and a pore-forming agent (e.g., PEG, with a final mass fraction of 15%) is then added. The mixture is thoroughly blended to obtain an adhesive layer solution. The liquid is applied to the surface of the ceramic layer (or, if no ceramic layer is present, directly to the surface of the base film). A portion of the solvent is pre-evaporated at 80 °C and then dried at 110 °C. The dried separator is then immersed in deionized water to dissolve and wash away the PEG, forming a porous adhesive layer. cathode foil

[0109] The cathode foil comprises a cathode current collector and a cathode film layer arranged on at least one side of the cathode current collector. The cathode film layer comprises an active cathode material.

[0110] For example, the cathode current collector has two surfaces facing each other in its thickness direction, and the cathode film layer is provided on any one or both of the two facing surfaces of the cathode current collector. In some embodiments, the cathode current collector can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector can comprise a base layer of polymer material and a metal layer formed on at least one surface of the polymer base layer.The composite current collector can be formed by forming a metal material (aluminium, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy or the like) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) or the like).

[0111] The present disclosure does not impose any specific restrictions on the active cathode material. For example, the active cathode material may comprise at least one of the following materials: lithium-containing phosphate with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present disclosure is not limited to these materials, and other conventional materials suitable for use as battery active cathode materials may also be employed. These active cathode materials may be used alone or in combination with two or more. Examples of lithium transition metal oxides include lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333 ), LiNi 0,5 Co 0,2 Mn 0,3 O2 (NCM 523 ), LiNi 0,5 Co 0,25 Mn 0,25 O2 (NCM 211 ), LiNi 0,6 Co 0,2 Mn ,2 O2 (NCM 622 ), LiNi 0,8 Co 0,1 Mn 0,1 O2 (NCM 811 ) and lithium nickel cobalt aluminum oxides (such as LiNi 0,85 Co 0,1 Al 0,05 Examples of lithium-containing phosphate with an olivine structure may include, but are not limited to, lithium-containing transition metal phosphate (such as lithium iron phosphate (such as LiFePO4 (LFP)), lithium iron phosphate-carbon composite, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate-carbon composite, lithium manganese iron phosphate, and lithium manganese iron phosphate-carbon composite).

[0112] In some embodiments, the active cathode material comprises particles of lithium-containing transition metal phosphate. These lithium-containing transition metal phosphate particles comprise a lithium-containing transition metal phosphate matrix and an encapsulating layer covering at least part of the surface of the lithium-containing transition metal phosphate matrix. The encapsulating layer contains the carbon element. The lithium-containing transition metal phosphate matrix is ​​designated by the following chemical formula. Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 0.8, 0.9 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ al + bl ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; where A comprises one or more of Na, K, and Mg; where Me comprises one or more of Mn, Fe, Co, and Ni; where M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; where X comprises one or more of S, Si, Cl, B, C, N and P; where Y comprises one or more of O and F.

[0113] The present disclosure does not impose any specific restrictions on the types of lithium-containing transition metal phosphate matrix. For example, at least one of the following can be selected: lithium iron phosphate (LFP), lithium manganese phosphate, lithium manganese iron phosphate, and the like. In some embodiments, the lithium-containing transition metal phosphate comprises lithium iron phosphate. The lithium-iron active cathode material exhibits good cycle performance and high safety, but its gram capacity is relatively low. By arranging the electrodes in a stacked configuration, the energy density of lithium-iron battery cells can be effectively improved.

[0114] The encapsulating layer of at least part of the surface of the lithium-containing transition metal phosphate matrix is ​​a carbon coating layer. Carbon exhibits excellent electrical conductivity, which is advantageous for electron transport. The carbon coating layer can significantly improve the electronic conductivity of lithium-containing transition metal phosphate material, thus compensating for its inherent weakness.

[0115] The carbon coating layer, which is present on at least a portion of the surface of the lithium-containing transition metal phosphate, can be detected using all methods known in the art. For example, by characterizing the lithium-containing transition metal phosphate using a coupling of a transmission electron microscope and an energy spectrum analyzer, it is possible to observe the carbon coating layer present on at least a portion of the surface of the lithium-containing transition metal phosphate. It should be noted that the elements in the carbon coating layer are not limited to carbon elements, but may also include other non-carbon elements. The carbon coating layer is not limited to a film-like form, but may also comprise an island-like, irregular, or discontinuous encapsulating layer.

[0116] In some embodiments, the lithium-containing transition metal phosphate contains the element titanium (Ti). Based on the mass of the lithium-containing transition metal phosphate, the mass fraction of Ti is 0.05% to 0.2%. For example, the mass fraction of Ti can be any value of 0.05%, 0.08%, 0.1%, 0.13%, 0.15%, 0.17%, 0.2%, or a value within a range formed by any two of these values. In lithium-containing transition metal phosphate, the element Ti can lower the transport barrier for lithium ions and increase the diffusion rate of lithium ions, thereby improving the dynamic properties and cycle performance of the battery.

[0117] In some embodiments, it is provided that D A50the particle size of the lithium-containing transition metal phosphate in the cumulative area distribution curve of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 70 nm to 3 µm, where D A50 represents the particle size value that corresponds to a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the particle size.

[0118] In the present disclosure, the term “particle” refers to particles in the cathode film layer whose complete boundaries are visible in the field of view at a certain magnification, for example 10,000x, and defects and scratches may be present inside the particles, but the interior of the particles is not visible with sufficiently complete boundaries to segment the particles.

[0119] The particle detection procedure is as follows: the cathode film layer is cut in the thickness direction of the electrode foil using an argon ion beam. After exposing the cut surface, this surface is observed with a scanning electron microscope (SEM). An image is acquired using a field emission scanning electron microscope (PEEM) in secondary electron mode at the non-edge position in the cut surface of the cathode film layer (after observing the edge of the electrode foil under the SEM, the field of view is adjusted to the center of the sample). An electron microscope image is acquired at 10,000x magnification, and the particles in the electron microscope image are analyzed using the software ImageJ (1.46r, Win64 version). The specific method for using the software ImageJ is as follows: loading a scanning electron microscope image to be analyzed;Particle detection using the Cellpose plug-in software, followed by manual correction; data reading and analysis using the ImageJ software. The specific method for particle detection with the Cellpose plug-in software is as follows: setting the "Segmentation Diameter" parameter (diameter in the "Segmentation" module) to 15 pixels, clicking "run cyto3" for particle detection, and manually marking the particles in the image that are not detected, not detected completely, or detected incorrectly by the software. The particles in the image that are not detected, not detected completely, or detected incorrectly by the software mainly include the following: 1. The particles are too large or have scratches on their surface, which prevents or incompletely detecting them;2. When sectioning with the argon ion beam, scratches are created on the particle surface. During the detection process, the software may incorrectly interpret these scratches as particle boundaries, leading to detection errors. 3. The particle cannot be detected because it is too small. 4. The particles are located at the edge of the electron microscope's field of view, and the particle's interior is penetrated by the edge. The morphology cannot be fully displayed, and the part is detected instead of the whole, resulting in detection errors. For the aforementioned particles that are not detected or exhibit detection errors, manual calibration is performed. The specific procedure is as follows: Deleting the large particles at the edges of the scanning electron microscope that cannot be fully displayed;Determine whether there are slits or scratches within other particles that are not identified or have detection errors, whereby, if there are no gaps or scratches within a particle, it is determined to be a single particle and manually marked based on the manually observed particle boundaries; determine, in response to the presence of a slit or scratch inside the particle, whether the slit or scratch penetrates the particle, and if not, determine that it is a single particle and perform manual detection; determine, in response to the slit or scratch penetrating the particle, whether the slit or scratch is linear or irregular; determine, in response to the irregular shape of the slit or scratch, that it is the boundary between particles, splitting the particles along the boundary;Performing a contrast comparison in response to the linear shape of the slit or scratch; determining, in response to an indistinct contrast comparison and the absence of a slit sensation, that the particle is a scratch, which is recognized as a single particle; determining, in response to a strong contrast comparison and the slit sensation, that it is the boundary between particles, which is recognized as two particles. After manual detection, the information irrelevant to the particles is deleted in the automatic image processing process, and the determination and detection of the particles in the image is completed.

[0120] The cross-sectional morphology of the cathode film layer along the thickness direction of the electrode foil differs from the state of the active cathode material in the Malvern laser scattering method and also from the state of the active cathode material when directly observed using scanning electron microscopy. Under roller pressure, the particles in the cathode film layer exhibit a good dispersion state; observing this cathode film layer is advantageous for effectively determining the objective situation regarding particle size, particle area, and the number of particles in the cathode film layer.

[0121] It is understood that the particles in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, in particular the particles larger than 50 nm, originate mainly from the active cathode material. Therefore, the present disclosure can accurately and objectively reproduce the distribution of the particles of the active cathode material of the cathode film layer in the electrode foil by observing and statistically analyzing the particle size in the cross-sectional area of ​​the cathode film layer.

[0122] Current technology typically uses the Malvern laser diffraction method to count the granularity of the active cathode material. However, investigations show that, due to the tendency of lithium-containing phosphate to agglomerate, test results obtained using the Malvern laser diffraction method, based on the laser scattering principle, often measure the particle size of the agglomerates. This cannot reflect the granularity of the active cathode material particles, let alone the dispersion state of the active cathode material in the film layer, since the degree of dispersion of the active cathode material in the film layer is improved during the rolling process for film formation.The test results obtained using the Malvern laser diffraction method correlate closely with the granularity, specific surface area, and degree of agglomeration of the active cathode material; therefore, the particle size determined using the Malvern laser diffraction method cannot be equated with the particle size determined statistically in the present disclosure, nor can it be transferred to the particle size determined statistically in the present disclosure.

[0123] D A50 -Test procedure: the specific calculation method for D A50The particle cross-section of the positive electrode film in the cut surface of the cathode film layer along the thickness direction of the electrode foil is as follows. Following the procedure described above, after particle identification and detection, the image is imported into the ImageJ software for analysis. The scale is set according to the scanning electron microscope image, and the Feret diameter and the area of ​​the particle cross-section in the cut surface of the cathode film layer along the thickness direction of the electrode foil are analyzed using the analysis functions "Feret Diameter," "Area Area," "Round," and "Solidity." According to the software manual (ImageJ User Guide IJ 1.46r), the "Feret" parameter is analyzed to represent the maximum distance between all parallel lines of the outer contour of the particle cross-section, which characterizes the particle size; and the "Area" parameter represents the pixel area of ​​the particle.Since particles with a size of less than 50 nm exhibit large errors in the statistical process, they are difficult to identify accurately. Furthermore, the particle size of the conducting medium is generally below 50 nm, which can lead to significant errors in the statistical results. Therefore, particles with a size below 50 nm are not considered in the statistical evaluation of the particle size in this disclosure, and the corresponding statistical particle data for Area, Roundness, or Solidity, indicated as "NaN," are discarded. To achieve the statistically significant sample size according to the method described above, each electrode array collects at least 10 scanning electron microscope images with non-overlapping fields of view and counts the particle size of at least 5000 particles.The particle sizes of at least 5000 particle cross-sections are arranged in ascending order. The cumulative area distribution curve of the particles in the cathode film layer is determined by plotting the particle size on the horizontal axis and the cumulative area fraction, calculated using the particle's area, on the vertical axis. A50 is the particle size value that corresponds to a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve.

[0124] For example, the D A50 of particles of the lithium-containing transition metal phosphate any value between 70 nm, 100 nm, 500 nm, 1 µm, 1.5 µm, 2 µm, 2.5 µm, 3 µm or a value within a range formed by any two of these values. Alternatively, the D A50The particles of the lithium-containing transition metal phosphate range from 100 nm to 2.5 µm. By using lithium iron phosphate particles of a suitable size, the diffusion path of the lithium ions can be shortened, and the expansion and contraction of the particle volume caused by the insertion and removal of lithium ions can be reduced. This, in combination with the binding effect of the adhesive layer, improves the structural stability of the stack and thus the overall cycle performance.

[0125] In some embodiments, it is provided that the particles of the active cathode material comprise particles of the lithium-containing transition metal phosphate, or are particles of the lithium-containing transition metal phosphate.

[0126] In some embodiments, it is provided that by designing a combination of particles of the lithium-containing transition metal phosphate of different sizes, the density of the cathode can be increased and thus the energy density of the battery can be improved.

[0127] In some embodiments, it is provided that the sphericity L A50 in the cumulative area distribution curve of the sphericity of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 0.70 to 0.75, where L A50 The sphericity is represented by a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the sphericity. Within a certain range, the sphericity (L) facilitates A50The relative sliding of particles of the lithium-containing transition metal phosphate between the particles, and thus the release of the internal voltage of the electrode through sliding, mitigates the destruction of the electrode foil structure by the stress relief of the electrode foil and improves battery performance. For example, the sphericity L A50 any value of 0.70, 0.71, 0.72, 0.73, 0.74 and 0.75 or a value within a range formed by any two of these values.

[0128] The measurement procedure for determining the cumulative area distribution curve of sphericity is as follows. The specific method for testing the sphericity of particles in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is as follows: after the determination and identification of the particles, the image is imported into the software ImageJ for analysis, and the scale is set according to the scanning electron microscope image. The particle size and the area of ​​the particles in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil are analyzed using the analysis functions "Feret Diameter", "Area", "Round", and "Solidity".According to the software manual (ImageJ User Guide IJ 1,46r), the parameter "Feret" is analyzed to represent the maximum distance between all parallel lines in the two-dimensional projection of the particle, which characterizes the particle size; the parameter "Area" represents the pixel area of ​​the particle, which characterizes the area of ​​the particle, since particles with a particle size smaller than 50 nm exhibit significant errors in the statistics and are difficult to identify, and since the particle size of the conducting medium is generally smaller than 50 nm and can therefore significantly distort the statistical results, particles with a particle size smaller than 50 nm are not considered in the particle size statistics in this disclosure, and the statistical particle data for which the Area is displayed as "NaN" are discarded.The parameter "Round" represents the ratio of the particle's pixel area to the area of ​​a circle whose diameter is given by the fitted major axis, and can be used to characterize the particle's sphericity. The closer the particle is to a sphere, the closer the ratio of the pixel area to the area of ​​a circle with the fitted major diameter as its diameter approaches 1. Therefore, the "Round" parameter of the particles, obtained through analysis, is used to characterize the particle's sphericity.

[0129] The sphericity of at least 5,000 obtained particles is arranged in ascending order, and the cumulative distribution curve of the sphericity of the particles in the cathode film layer is obtained with the sphericity as the horizontal axis and the cumulative area fraction as the vertical axis. L A50The sphericity L-value corresponds to the value at which the cumulative area fraction of the vertical axis in the cumulative distribution curve of the sphericity L-value is 50%. Compared to the point value, L A50 reflect the entire sphericity of the particles in the cathode film layer, i.e., the degree to which they approximate a sphere; compared to the mean value, it can reduce the influence of extreme values ​​during the testing process and improve the reliability of the test results.

[0130] During the charging and discharging process, deintercalation and consumption of lithium occur in the battery, and the molar content of lithium varies depending on the discharge state. In the enumeration of the active cathode material in the present disclosure, the molar content of lithium represents the initial state of the material, i.e., the state before the addition of the active cathode material used in the battery system, and the molar content of lithium changes after the charging and discharging cycle.

[0131] In the list of active cathode material in the present disclosure, the molar content of O is only a theoretical value. Due to the release of oxygen from the crystal lattice, the molar content of oxygen changes, and the actual molar content of O fluctuates.

[0132] In some embodiments, the cathode film layer may optionally also include an adhesive. For example, the adhesive may comprise at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0133] In some embodiments, the cathode film layer optionally includes a conductive material. For example, the conductive material can comprise at least one of superconducting carbon, carbon black, carbon black, Ketjen carbon black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0134] In some embodiments, the porosity of the cathode film layer is specified as being between 23% and 32%. This porosity ensures both high density and good wettability, thus guaranteeing the battery cell high energy density and good cycle performance. For example, the porosity of the cathode film layer can be any value of 23%, 25%, 27%, 29%, 30%, or 32%, or a value within any range formed by any two of these values.

[0135] In the present disclosure, the porosity of the cathode film can be measured using instruments and methods known in this field. For example, the measurement can be carried out with a real density meter, with reference to the standard GB / T24586-2009. Specifically, the cathode film of a battery cell with 0% state of charge (SOC) is disassembled, cut into 3 mm × 3 mm pieces, and the apparent volume V0 of the sample is measured (the apparent volume of the sample is the thickness of the cathode film layer multiplied by the area of ​​the sample). Subsequently, the actual volume of the sample is determined using a real density meter.Specifically, the sample is placed in the sample test chamber, nitrogen gas is introduced into the sample test chamber, the sample test chamber is connected to the reference chamber, and the pressure after stabilization is recorded, measuring the pressure in the reference chamber before connection with the sample chamber as well as the pressure in the reference chamber after stable connection with the sample chamber. Subsequently, according to Bohr's law PV = nRT, the porosity of the sample = porosity volume / apparent volume.

[0136] In some embodiments, the density of the cathode foil is specified as 2.25 g / cm³. 3 up to 2.65g / cm³ 3The density of the cathode foil, within the aforementioned range, enables the battery cell to achieve a high energy density while simultaneously ensuring wetting with the electrolyte solution and the battery's cycle performance. For example, the density of the cathode foil could be any value of 2.25 g / cm³. 3 , 2.30 g / cm³ 3 , 2.35 g / cm³ 3 , 2.40 g / cm³ 3 , 2.45 g / cm³ 3 , 2.50 g / cm³ 3 , 2.60 g / cm³ 3 and 2.65 g / cm² 3 or a value within a range formed by any two of these values. Alternatively, the density of the cathode foil is 2.3 g / cm³. 3 up to 2.45g / cm³ 3 .

[0137] In the present disclosure, the cathode foil density refers to the density of the cathode foil of the battery cell at a state of charge (SOC) of 0%, which can be measured using the following method. The cathode foil is removed from the battery cell at a state of charge (SOC) of 0%, and the density of the cathode foil is measured. For example, a single-sided coated cathode foil is taken (in the case of a double-sided coated electrode foil, the cathode film layer on one side is wiped off first), cut into small slices with an area of ​​S1, weighed (M1), and its thickness H1 is measured. Then, the cathode film layer of the weighed cathode foil is wiped off, and the weight of the cathode current collector is weighed and recorded as M0, and its thickness H0 is measured.The one-sided coating weight of the cathode foil = (the weight of the cathode foil M1 - the weight of the cathode current collector M0) / S1, the thickness of the cathode film layer = the thickness of the cathode foil H1 - the thickness of the cathode current collector H0, the compaction density of the cathode foil = the one-sided coating weight of the cathode film layer / the thickness of the cathode film layer.

[0138] In some embodiments, the one-sided coating weight of the cathode film layer is 0.33g / 1540.25 mm². 2 up to 0.43g / 1540.25 mm 2 The one-sided coating weight of the cathode film layer is within a suitable range, allowing the battery cell to exhibit high energy density and promoting ion transport. For example, the one-sided coating weight of the cathode film layer is 0.33 g / 1540.25 mm². 2 , 0.35 g / 1540.25 mm 2 , 0.36 g / 1540.25 mm 2 , 0.37 g / 1540.25 mm2 , 0.38 g / 1540.25 mm 2 , 0.39 g / 1540.25 mm 2 , 0.40 g / 1540.25 mm 2 , 0.41 g / 1540.25 mm 2 or 0.43 g / 1540.25 mm 2 Alternatively, the single-sided coating weight of the cathode film layer is 0.36 g / 1540.25 mm². 2 up to 0.40g / 1540.25 mm 2 .

[0139] In the present disclosure, the one-sided coating weight of the cathode film layer can be tested using methods known in this field. The cathode film to be tested can be a manufactured cathode film or a cathode film obtained by dismantling a battery. The following explanation uses the latter as an example to illustrate the test process. By dismantling a battery with a 0% state of charge (SOC), the cathode film is obtained; this cathode film is then formed into a circular disk with an area of ​​1540.25 mm². 2The mass of this circular disk is cut and weighed as m1. Subsequently, the cathode film layer arranged on one side of the circular disk is removed, the circular disk is weighed as m2, and m1 - m2 is used as the one-sided coating weight of the cathode film layer.

[0140] In some embodiments, the cathode foil can be produced as follows: the above-mentioned components for producing the cathode foil, for example the active cathode material, the conductive agent, the adhesive and all other components, are dispersed in a solvent (e.g. N-methylpyrrolidone) to form a cathode slurry; the cathode slurry is applied to the cathode current collector and after processes such as drying and cold pressing, the cathode foil can be obtained. Anode foil

[0141] The anode foil comprises an anode current collector and an anode film layer arranged on at least one side of the anode current collector. The anode film layer comprises an active anode material.

[0142] For example, the anode current collector has two surfaces facing each other in the thickness direction, and the anode film layer is provided on one or both of the two facing surfaces of the anode current collector.

[0143] In some embodiments, the anode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector can comprise a base layer of polymer material and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, or the like) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), or the like).

[0144] In some embodiments, the active anode material can be any battery active anode material known in the art. For example, the active anode material can comprise at least one of the following materials: synthetic graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, silicon-oxygen compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy.However, the present disclosure is not limited to these materials, and other conventional materials can also be used as the active anode material of the battery. These active anode materials can be used alone or in combination with one or more of them.

[0145] In some embodiments, the active anode material comprises graphite. The particle size Dv50 of the graphite is 13 µm to 22 µm. The use of graphite with a larger particle size (Dv50) within the aforementioned range is advantageous for increasing the compaction density of the electrode foil and thus for increasing the volume energy density of the battery. Although graphite with this particle size range lengthens the lithium ion transfer path within the graphite and increases polarization, which adversely affects the cycle performance of the battery cell, the electrolyte solution used in the single cell of the present disclosure, which contains a certain amount of chain carbonate as a solvent, exhibits good flowability and can effectively improve the wetting of the anode foil, thus improving both the volume energy density of the battery and its cycle performance.For example, the particle size Dv50 of graphite is any value from 13 µm, 14 µm, 15 µm, 16 µm, 17 µm, 18 µm, 19 µm, 20 µm, 21 µm to 22 µm, or a value within a range formed by any two of these values. Alternatively, the particle size Dv50 of graphite is 14.5 µm to 20 µm.

[0146] In this embodiment of the disclosure, the volume-average granularity Dv50 of the material refers to the granularity corresponding to 50% of the volume distribution, the volume-average granularity Dv10 of the material denotes the granularity corresponding to 10% of the volume distribution, and can be determined using equipment and methods known in this field. For example, the active anode material can be used as a sample; alternatively, the anode foil can be removed from the battery cell at 0% state of charge (SOC) and the anode film layer scraped off to remove organic matter and obtain the active anode material. According to test standard GB / T 19077-2016, the Dv50 of the particles can be tested using a Mastersizer 2000E laser particle size analyzer.

[0147] In some embodiments, the anode film layer optionally includes an adhesive. The adhesive can be selected from at least one of the following: styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0148] In some embodiments, the anode film layer optionally includes a conductive material. The conductive material can be selected from at least one of the following: superconducting carbon, carbon black, carbon black, Ketjen carbon black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0149] In some embodiments, the anode film layer may optionally also include other additives, such as a thickening agent (e.g. sodium carboxymethylcellulose (CMC-Na) ).

[0150] In some embodiments, the porosity of the anode film layer is specified as being between 23% and 32%. Within this range, the porosity of the anode film layer can simultaneously ensure high compaction density and good wetting, thereby guaranteeing that the battery cell exhibits high energy density and good cycle performance. For example, the porosity of the anode film layer can be any value of 23%, 32%, 25%, 27%, 30%, or 32%, or a value within a range formed by any two of these values.

[0151] In some embodiments, the compression density of the anode foil is specified as 1.3 g / cm³. 3 up to 1.55g / cm³ 3The density of the anode foil, within the aforementioned range, enables the battery cell to achieve a high energy density while simultaneously ensuring wetting with the electrolyte solution and the battery's cycle performance. For example, the density of the anode foil could be any value of 1.3 g / cm³. 3 , 1.35g / cm³ 3 , 1.4g / cm³ 3 , 1.45g / cm³ 3 , 1.5g / cm³ 3 , 1.55g / cm³ 3 or a value within a range formed by any two of these values. Alternatively, the compaction density of the anode foil is 1.4 g / cm³. 3 up to 1.5g / cm³ 3 .

[0152] In some embodiments, the one-sided coating weight of the anode film layer is 0.15g / 1540.25 mm². 2 up to 0.207g / 1540.25 mm 2The one-sided coating weight of the anode film layer is within a suitable range, allowing the battery cell to exhibit high energy density and promoting ion transport. For example, the one-sided coating weight of the cathode film layer is 0.15 g / 1540.25 mm². 2 , 0.17 g / 1540.25 mm 2 , 0.18 g / 1540.25 mm 2 , 0.19 g / 1540.25 mm 2 , 0.20 g / 1540.25 mm 2 or 0.207 g / 1540.25 mm 2 Alternatively, the one-sided coating weight of the anode film layer is 0.17 g / 1540.25 mm². 2 up to 0.2g / 1540.25 mm 2 .

[0153] The measurement method described in the present disclosure for the porosity, the compaction density of the anode foil and the one-sided coating weight of the anode film layer corresponds essentially to the corresponding measurement method for the cathode foil described above, which is not repeated here.

[0154] In some embodiments, the anode foil can be produced as follows: Dispersing the above-mentioned components for the production of the anode foil, such as the active anode material, the conductive agent, the adhesive, and all other components in a solvent (such as deionized water) to form an anode slurry; the anode slurry is applied to the anode current collector, and after processes such as drying and cold pressing, the anode foil can be obtained.

[0155] A typical battery cell comprises a cathode foil, an anode foil, an electrolyte, and a separator film. During the charging and discharging process, active ions are inserted and removed between the cathode and anode foils. The electrolyte conducts ions between the cathode and anode foils. The separator film is placed between the cathode and anode foils, primarily to prevent a short circuit between the cathode and anode while allowing the passage of ions.

[0156] In the battery cell of the present disclosure, the aforementioned cathode foil, the anode foil, and the separating film are produced into an electrode assembly by a lamination process. The present disclosure does not impose any particular restrictions on the lamination process, and conventional methods may be used for its manufacture.

[0157] In some embodiments, the hot pressing of the stacked electrode assembly is maintained at 2 MPa to 4 MPa and 60°C to 100°C for 90 s to 200 s. Hot pressing melts the adhesive layer, thus bonding the cathode foil and the anode foil on both sides of the separating film to this separating film.

[0158] In some embodiments, the battery cell may include an outer packaging. The outer packaging can be used to package the electrode assembly and the electrolyte solution.

[0159] In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer packaging of the battery cell can also be a soft packaging, such as a bag-like soft packaging. The material of the soft pack can be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate, among others.

[0160] The present disclosure is not subject to any particular restrictions regarding the shape of the battery cell, and it can be circular-cylindrical, square, or any other shape. For example, it shows Fig. 3 a battery cell 5 with a square structure as an example.

[0161] In some embodiments, it refers to Fig.4. The outer packaging can comprise a housing 51 and a cover assembly 53. The housing 51 can comprise a base plate and a side plate connected to the base plate, and the base plate and side plates enclose and form a receiving space. The housing 51 has an opening that communicates with the receiving space, and the cover assembly 53 can cover the opening to close the receiving space. An electrode assembly 52 can be produced from the cathode foil, the anode foil, and the separator film by a winding or lamination process. The electrode assembly 52 is encapsulated in the receiving space. The electrolyte solution wets the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and the person skilled in the art can select one according to the specific practical requirements. Battery device

[0162] A second aspect of the present disclosure further relates to a battery device.

[0163] The battery device of the present disclosure can comprise one or more battery cell arrangements to provide voltage and capacity. A battery cell arrangement can comprise several battery cells provided in the first aspect described above, which are connected in series, parallel, or in a mixed configuration via a bus component.

[0164] In some embodiments, it is provided that a battery cell arrangement is typically formed by the arrangement of several battery cells.

[0165] For example, the battery cell arrangement can be a battery module formed by arranging and securing several battery cells in an independent module. For instance, a battery module can be formed by bundling several battery cells with cable ties.

[0166] For example, the battery cell arrangement can also be incorporated into the housing by attaching several battery cells directly to the housing.

[0167] For example, the housing can comprise a first housing and a second housing. The first and second housings snap together, so that the interior of the housing forms a sealed space to accommodate the battery cell assembly. "Sealed" here means "covered" or "closed" and can be sealed or unsealed. The first housing can be a top cover or a bottom plate.

[0168] For example, the housing can comprise a top cover, a frame, and a base plate. The top cover and the base plate are each connected to the frame, so that the interior of the housing forms a sealed space to accommodate the battery cell assembly.

[0169] In some embodiments, the housing can be used as part of the vehicle's chassis structure. For example, part of the housing can become at least part of the vehicle's floor covering, or part of the housing can become at least part of a cross member and a longitudinal member of the vehicle.

[0170] In some embodiments, the battery device may be a battery pack comprising a housing and one or more battery cell assemblies contained within the housing.

[0171] Fig.Figure 5 shows a battery module 4 as an example. With reference to Fig. In battery module 4, several battery cells 5 can be arranged sequentially along the longitudinal direction of the battery module 4. Of course, the arrangement can also be any other way. The multiple battery cells 5 can additionally be secured by fastening elements.

[0172] Optionally, the battery module 4 can also include an outer shell with a receiving space, and the multiple battery cells 5 are received in the receiving space.

[0173] Fig. 6 and Fig. Figure 7 shows a battery pack 1 as an example. Referring to Fig. 6 and Fig.7. The battery pack 1 can comprise a battery box and several battery modules 4 arranged within the battery box. The battery box comprises an upper housing 2 and a lower housing 3, and the upper housing 2 can cover the lower housing 3, forming a sealed space for the battery module 4. The arrangement of the multiple battery modules 4 within the battery box is arbitrary. Power-consuming device

[0174] A third aspect of the present disclosure provides a power-consuming device, wherein the power-consuming device comprises a battery device provided in the second aspect of the present disclosure.

[0175] The power-consuming device mentioned in the embodiments of this disclosure comprises the battery device provided in the second part of this disclosure. The battery device can be used either as the power supply for the power-consuming device or as the 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, and the like), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, and the like), electric trains, ships and satellites, energy storage systems, and the like.

[0176] Depending on the usage requirements, a battery cell, a battery module or a battery pack can be selected as the power-consuming device.

[0177] Fig. Figure 8 shows an example of a power-consuming device. This device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. To meet the power-consuming device's requirements for high performance and energy density of the secondary battery, a battery pack or battery module can be used.

[0178] Another example of a power-consuming device could be a mobile phone, a tablet computer, a laptop computer, or the like. The device typically needs to be lightweight and thin, and a battery cell can be used as the power source. Examples of implementation

[0179] The following are examples of embodiments of the present disclosure. These embodiments are exemplary and serve only to illustrate the present disclosure; they should not be construed as limiting it. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the technical literature or the product instructions must be followed. Any reagents or instruments used without manufacturer information are exclusively commercially available products. Exemplary embodiment 1(1) Production of the cathode foil

[0180] The active cathode material (lithium iron phosphate with coated carbon, formula: LiFePO4, particle size Da50 = 700 nm, carbon content: 2%), polyvinylidene fluoride, and conductive carbon black are mixed in a weight ratio of 97:2.2:0.8 and then added to the solvent N-methylpyrrolidone. The mixture is stirred uniformly, and the viscosity is adjusted to form a cathode slurry. The cathode slurry is applied to the surface of both sides of the aluminum foil of the cathode current collector (thickness: 15 µm) to form a cathode film layer (the coating weight on one side is 0.38 g / 1540.25 mm²). 2 ), after drying and hot pressing, the cathode foil is obtained, which has a porosity of 29% and a compaction density of 2.4 g / cm³. 3 exhibits. (2) Production of the anode foil

[0181] The active anode material (Dv50 is 15 µm graphite), the conductive agent (conductive carbon black), the adhesive (styrene-butadiene rubber (SBR)), and the thickener (sodium carboxymethylcellulose (CMC)) are mixed in a mass ratio of 95.5:1.0:2.0:1.5. Deionized water is added, and the mixture is stirred and dispersed to produce an anode slurry. The anode slurry is then applied to the surface of both sides of the copper foil (the coating weight on one side is 0.185 g / 1540.25 mm²). 2 ), after drying, compacting, cutting and the production of the film, an anode film with a porosity of 28% and a compaction density of 1.4 g / cm³ is obtained. 3 receive. (3) Preparation of the electrolyte solution

[0182] In a glovebox with an argon atmosphere (H₂O < 0.1 ppm, O₂ < 0.1 ppm), the organic solvents ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are mixed uniformly. Lithium hexafluorophosphate is then added and dissolved in an organic solvent to achieve a lithium hexafluorophosphate concentration of 1.05 mol / L in the electrolyte solution. Vinylene carbonate (VC) is then added, and the mixture is stirred until homogeneous to obtain the electrolyte solution from embodiment 1.

[0183] Based on the total mass of the electrolyte solution, the mass fraction of dimethyl carbonate is 27.2%, the mass fraction of ethyl methyl carbonate is 29.9%, the mass fraction of ethylene carbonate is 28.1% and the mass fraction of vinylene carbonate is 2.6%. (4) Release film

[0184] A 7 µm thick polyethylene film is used as the base film. The ceramic material, consisting of aluminum oxide powder (particle size 1 µm), and the adhesive, consisting of polyvinylidene fluoride (PVDF), are added to the solvent, N-methylpyrrolidone (aluminum oxide:PVDF:solvent mass ratio 5:1:10), and mixed uniformly to form a ceramic layer slurry. This ceramic layer slurry is applied to both sides of the base film and then dried to form the ceramic layer. Polyvinylidene fluoride (PVDF) is added to the solvent N-methylpyrrolidone and thoroughly mixed. Polyethylene glycol (PEG) is then added as a pore-forming agent to create an adhesive layer solution, with a mass fraction of PVDF at 20% and PEG at 10%.The adhesive solution is coated onto the ceramic layer, pre-evaporated at 80 °C, and dried at 110 °C. It is then immersed in deionized water to dissolve the polyethylene glycol, thus obtaining the release film. The release film produced in this way has a thickness of 1.6 µm on one side for the ceramic layer, a thickness of 0.65 µm on one side for the adhesive layer, and a porosity of 35% for the release film, which is measured using the following method. (5) Preparation of battery cells

[0185] 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. The electrode assembly is then formed through a lamination process. The electrode assembly is placed in the outer packaging, dried, and then filled with the aforementioned electrolyte solution. After vacuum sealing, settling, forming, and adjustment, a battery cell is obtained. Characterization test of the release film(1) Coating thickness

[0186] The release film is polished in the thickness direction using an argon-ion cross-section polisher (e.g., argon-ion cross-section polisher type IB-09010 CP, JEOL Corporation, Japan) (argon flow rate 0.12 MPa, polishing time 90 min) to obtain a cross-section of the release film in the thickness direction. Under a field emission scanning electron microscope, it is observed that the base film, the ceramic layer, and the adhesive layer are all simultaneously present in the field of view. To measure the thickness of the ceramic layer and the adhesive layer on one side of the base film, five locations in five different fields of view are selected, and the average value is calculated. (2) Porosity of the separating film

[0187] The porosity of the release film is measured according to the standard GB / T 24586-2009. Performance test for the electrode foil(1) Compaction density of the electrode foil

[0188] The compaction density is checked and calculated using the method described above, by dividing the mass of the film layer of the electrode foil by the volume of the film layer of the electrode foil. (2) Test of the porosity of the electrode foil

[0189] According to GB / T24586-2009, the cathode foil and the anode foil are cut to a size of 3 mm × 3 mm. A real density meter is used to measure the porosity of the cathode foil and the anode foil, and nitrogen is introduced. Battery cell performance test Cyclic performance test

[0190] At 25°C, the battery cell is charged to 3.65V with a constant power of 0.5P and then left to stand for 30 minutes. It is then discharged to 2.5V with a constant power of 0.5P, left to stand for 2 hours, and the discharge capacity is recorded. The above test steps are repeated 1000 times. The capacity retention rate after 1000 cycles is calculated as (discharge capacity after the 1000th cycle / discharge capacity after the first cycle) × 100%. Examples 2 to 8

[0191] The manufacturing process of embodiments 2 to 8 is similar to that of embodiment 1, except that the composition of the organic solvent in the electrolyte solution and the coating thickness of the separating film are adapted according to Table 1. Example 9

[0192] The manufacturing process of embodiment 9 is similar to that of embodiment 1, except that the separating film is not provided with a ceramic layer. Comparative examples 1 to 2

[0193] The manufacturing process of comparative examples 1 and 2 is similar to that of embodiment 1, except that the composition of the organic solvent in the electrolyte solution is adapted according to Table 1. Comparative examples 3 to 4

[0194] The manufacturing process of comparative examples 3 and 4 is similar to that of embodiment 1, except that the composition of the organic solvent in the electrolyte solution is adapted according to Table 1, and the separating film is not provided with a ceramic layer.

[0195] The performance of the battery cell produced in embodiments 2 to 9 and comparison examples 1 to 4 is measured using the same test procedure as in embodiment 1; the specific results are shown in Table 1. Table 1 Serial number DMCA content EMC salary Total chain carbonate content EC salary Coating method of the adhesive layer Morphology of the adhesive layer Adhesive layer thickness (µm) Thickness of the ceramic layer (µm) Capacity retention rate after 1000 cycles at 25 °C Example 1 27,2% 29,9% 57,1% 28,1% Oil-based porous and continuous 0,65 1,6 93,70% Example 2 22,0% 22,0% 43,9% 41,3% Oil-based porous and continuous 0,65 1,6 92,70% Example 3 26,4% 26,4% 52,7% 32,5% Oil-based porous and continuous 0,65 1,6 93,40% Example 4 35,1% 26,4% 61,5% 23,7% Oil-based porous and continuous 0,65 1,6 93,00% Example 5 42,2% 28,1% 70,3% 14,9% Oil-based porous and continuous 0,65 1,6 92,00% Example 6 27,2% 29,9% 57,1% 28,1% Oil-based porous and continuous 0,2 1,6 93,30% Example 7 27,2% 29,9% 57,1% 28,1% Oil-based porous and continuous 1 1,6 92,80% Example 8 27,2% 29,9% 57,1% 28,1% Oil-based porous and continuous 2 1,6 91,70% Example 9 27,2% 29,9% 57,1% 28,1% Oil-based porous and continuous 0,65 no 91,90% Comparative example 1 17,6% 17,6% 35,1% 50,1% Oil-based porous and continuous 0,65 1,6 88,90% Comparative example 2 17,6% 55,4% 74,7% 10,5% Oil-based porous and continuous 0,65 1,6 75,60% Comparative example 3 17,6% 17,6% 35,1% 50,1% Oil-based porous and continuous 0,65 no 88,60% Comparative example 4 17,6% 55,4% 74,7% 10,5% Oil-based porous and continuous 0,65 no 75,20%

[0196] As can be seen from Table 1 above, according to embodiments 1 to 9 of the present disclosure, a release film with an adhesive layer obtained by oil-based coating is used together with an electrolyte solution having a chain carbonate content between 43% and 71%. Compared to Comparative Example 1 and Comparative Example 2, in which the same release film as in embodiment 1 is used, but with a lower or higher chain carbonate content, and compared to Comparative Example 3 and Comparative Example 4, in which the same release film as in embodiment 9 is used, also with a lower or higher chain carbonate content, a significantly improved cycle performance is achieved in each case.These results suggest that an appropriate amount of chain carbonate can improve the wettability of the separating film by the electrolyte solution with good adhesion, thereby increasing the cycle performance of the battery.

[0197] It should be noted that the present disclosure is not limited to the embodiments mentioned above. The embodiments mentioned above are merely examples, and all embodiments that exhibit essentially the same structure and effects as the technical idea within the technical solution of the present disclosure are all included within the technical scope of the present disclosure. Furthermore, other embodiments in which various modifications conceivable to a person skilled in the art are added to the embodiments, and some components of the embodiments are combined to form the other embodiments, are also included within the scope of the present disclosure without departing from the core 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 202510830566.5

[0001] Cited non-patent literature

[0000] Norm JY / T020 - 1996

[0080]

Claims

[1] Battery cell comprising a stacked electrode arrangement and an electrolyte solution, wherein the stacked electrode arrangement comprises a cathode foil, a separator film and an anode foil stacked on top of each other, wherein the separating film comprises a base film and coatings arranged on both sides of the base film, wherein the coating comprises an adhesive layer, wherein the adhesive layer is a continuous layer with a porous structure, and wherein the adhesive layer comprises a fluoropolymer; wherein the electrolyte solution comprises a chain carbonate, wherein the mass fraction of the chain carbonate is 43% to 71% relative to the total mass of the electrolyte solution. [2] Battery cell according to claim 1, wherein the mass fraction of the chain carbonate is 52% to 62% in relation to the total mass of the electrolyte solution. [3] Battery cell according to claim 1 or 2, wherein the chain carbonate comprises dimethyl carbonate and / or ethyl methyl carbonate. [4] Battery cell according to claim 1 or 2, wherein the electrolyte solution also comprises cyclic carbonate. [5] Battery cell according to claim 4, wherein the mass fraction of the cyclic carbonate is 14% to 42% in relation to the total mass of the electrolyte solution. [6] Battery cell according to claim 1, wherein the fluoropolymer comprises one or more of polyvinylidene fluoride, vinylidene fluoride trifluorochloroethylene copolymer, vinylidene fluoride hexafluoropropylene copolymer, vinylidene fluoride trifluorochloroethylene hexafluoropropylene copolymer, vinylidene fluoride tetrafluoroethylene hexafluoropropylene copolymer and vinylidene fluoride trifluorochloroethylene tetrafluoroethylene hexafluoropropylene copolymer. [7] Battery cell according to claim 1 or 2, wherein the thickness of the adhesive layer on one side is 0.15 µm to 2 µm. [8] Battery cell according to claim 1, wherein the coating further comprises a ceramic layer arranged between the base film and the adhesive layer. [9] Battery cell according to claim 8, wherein the ceramic layer comprises one or more of aluminium oxide, boehmite, silicon dioxide, magnesium oxide, titanium oxide, tin oxide, calcium oxide, zirconium oxide, barium sulfate, yttrium oxide, zinc oxide, silicon carbide, magnesium fluoride, barium titanate, aluminium hydroxide, magnesium hydroxide and calcium hydroxide. [10] Battery cell according to claim 8 or 9, wherein the thickness of the ceramic layer on one side is 0.5 µm to 4 µm. [11] Battery cell according to claim 1, wherein the thickness of the base film is 7µm to 9µm. [12] Battery cell according to claim 1, wherein the cathode foil comprises a cathode current collector and a cathode film layer arranged on at least one side of the cathode current collector, wherein the cathode film layer comprises an active cathode material, wherein the active cathode material comprises particles of the lithium-containing transition metal phosphate, wherein the particles of the lithium-containing transition metal phosphate comprise a lithium-containing transition metal phosphate matrix and an encapsulating layer located on at least a part of the surface of the lithium-containing transition metal phosphate matrix, wherein the encapsulating layer contains a carbon element, wherein the chemical formula of the lithium-containing transition metal phosphate matrix is ​​as follows: Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 0.8, 0.9 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; 3 ≤ z1 ≤ 5; where A comprises one or more of Na, K, and Mg; where Me comprises one or more of Mn, Fe, Co, and Ni; where M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; where X comprises one or more of S, Si, Cl, B, C, N and P; where Y comprises one or more of O and F. [13] Battery cell according to claim 12, wherein the lithium-containing transition metal phosphate comprises lithium iron phosphate. [14] Battery cell according to claim 12 or 13, wherein the lithium-containing transition metal phosphate contains the element Ti, wherein the mass fraction of the element Ti is 0.05% to 0.2% based on the mass of the lithium-containing transition metal phosphate. [15] Battery cell according to claim 12 or 13, wherein the D A50-value of the particles of the lithium-containing transition metal phosphate in the cumulative area distribution curve of the particle size of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 70 nm to 3 µm, where D A50 represents the particle size value that corresponds to a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the particle size. [16] Battery cell according to claim 12 or 13, wherein the sphericity L A50 in the cumulative area distribution curve of the sphericity of the particles of the lithium-containing transition metal phosphate, measured in the cross-sectional area of ​​the cathode film layer along the thickness direction of the cathode foil, is 0.70 to 0.75, where L A50The sphericity represents a cumulative area fraction of 50% on the vertical axis in the cumulative area distribution curve of the sphericity. [17] Battery cell according to claim 12, wherein the porosity of the cathode foil is 23% to 32%. [18] Battery cell according to claim 12 or 13, wherein the compression density of the cathode foil is 2.25g / cm³ 3 up to 2.65g / cm³ 3 amounts. [19] Battery cell according to claim 18, wherein the density of the cathode foil is 2.3g / cm³ 3 up to 2.45g / cm³ 3 amounts. [20] Battery cell according to claim 12 or 13, wherein the one-sided coating weight of the cathode film layer is 0.33g / 1540.25 mm² 2 up to 0.43g / 1540.25 mm 2 amounts. [21] Battery cell according to claim 20, wherein the one-sided coating weight of the cathode film layer is 0.36g / 1540.25 mm² 2 up to 0.40g / 1540.25 mm 2 amounts. [22] Battery cell according to claim 1 or 2, wherein the anode foil comprises an anode current collector and an anode film layer arranged on at least one side of the anode current collector, wherein the porosity of the anode foil is 23% to 32%. [23] Battery cell according to claim 1 or 2, wherein the compression density of the anode foil is 1.3g / cm³ 3 up to 1.55g / cm³ 3 amounts. [24] Battery cell according to claim 23, wherein the compression density of the anode foil is 1.4 g / cm³ 3 up to 1.5g / cm³ 3 amounts. [25] Battery cell according to claim 22, wherein the one-sided coating weight of the anode film layer is 0.15g / 1540.25 mm² 2 up to 0.207g / 1540.25 mm 2 amounts. [26] Battery cell according to claim 25, wherein the one-sided coating weight of the anode film layer is 0.17 g / 1540.25 mm² 2 up to 0.2g / 1540.25 mm 2 amounts. [27] Battery cell according to claim 1 or 2, wherein the anode foil comprises an anode film layer, wherein the anode film layer comprises an active anode material, wherein the active anode material comprises graphite, wherein the particle size Dv50 of the graphite is 13 µm to 22 µm. [28] Battery cell according to claim 27, wherein the particle size Dv50 of the graphite is 14.5 µm to 20 µm. [29] Battery cell according to claim 1 or 2, wherein the porosity of the separating film is 28% to 50%. [30] Battery cell according to claim 29, wherein the porosity of the separating film is 31% to 40%. [31] Battery device comprising a battery cell according to any one of claims 1 to 30. [32] Power-consuming device comprising a battery device according to claim 31.

Images