Battery cell, battery device, power-consuming device and energy storage device

Abstract

Battery cell, characterized in that the battery cell comprises a laminated battery cell, wherein the laminated battery cell comprises a cathode foil, a separator and an anode foil stacked one behind the other; wherein the cathode foil comprises a cathode current collector main body, a cathode tab and an active cathode material layer, wherein the active cathode material layer is arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, wherein the cathode tab is arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprises a main body region and a thinned region arranged on one side of the main body region facing the cathode tab, wherein the thickness of the thinned region is less than that of the main body region; wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles which are provided with a carbon material on at least part of their surface; wherein the one-sided thickness H of the main body area is 70 µm to 120 µm when the battery cell is in a fully discharged state; where, with reference to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that meets a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.6 to 0.8.

Description

Cross-reference

[0001] The present application refers to the international PCT patent application No. PCT / CN2025 / 094369, filed on May 12, 2025, entitled “Battery cell, battery device, power-consuming device and energy storage device”, which is incorporated into this application by reference. Technical field

[0002] The present application relates to the field of battery technology and in particular to a battery cell, a battery device, a power-consuming device and an energy storage device. Technical background

[0003] In recent years, battery cells have been widely used in energy storage systems such as hydroelectric, thermal, wind and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0004] As the market demands greater range and longer battery lifespans, higher demands are being placed on battery capacity, cycle life, and safety performance. However, with current technologies, achieving simultaneous improvements in these areas is difficult, and balancing the two has become a technical challenge that urgently needs to be addressed. Disclosure of registration

[0005] The present application is made with regard to the aforementioned problems and its aim is to provide a battery cell with high energy density, good cycle performance and safety.

[0006] A first aspect of the present application relates to a battery cell comprising a laminated battery cell, the laminated battery cell comprising a cathode foil, a separator and an anode foil, which are arranged stacked one behind the other; wherein the cathode foil comprises a cathode current collector main body, a cathode tab and an active cathode material layer, the active cathode material layer being arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, the cathode tab being arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprising a main body region and a thinned region being arranged on one side of the main body region facing the cathode tab, the thickness of the thinned region being less than that of the main body region;wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles that are provided with a carbon material on at least part of their surface; wherein the one-sided thickness H of the active cathode material layer is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer 11 along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness of the battery cell L; A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.6 to 0.8.

[0007] The battery cells of the embodiments of the present application improve the problems of current collector leakage and lithium precipitation and take into account both cycle life and safety performance while maintaining high capacity.

[0008] Without being bound to any theory, this could be due to the following reasons: by using a laminated battery cell structure, the presence of invalid space within the battery cell can be reduced and the unavoidable corner gaps and interlayer gaps during the winding process can be effectively eliminated, thus making the entire battery cell structure more compact, thereby improving space utilization, increasing the volume energy density of the battery cell and increasing the battery capacity; furthermore, the one-sided thickness H of the main body area is in the range of 70 µm to 120 µm, with a higher charge of active substance, thereby further improving the energy density of the battery.

[0009] Furthermore, the slurry forming the battery film layer is a non-Newtonian fluid with rheological properties, including shear thinning and thixotropy. During coating, the viscosity of the slurry decreases significantly under shear stress (shear thinning), which helps to reduce coating resistance and achieve good surface smoothness. After coating, the viscosity of the slurry gradually recovers (thixotropy) when the shear stress is removed, forming a thinner zone. Appropriate thixotropy helps to prevent lateral diffusion of the slurry after coating and improves the dimensional stability of the thinner zone at the coating interface. During thick coating processes, the unidirectional areal density of the slurry increases.Under the influence of gravity, the diluted area at the edge tends to distribute unevenly, leading to misalignment. Therefore, optimizing the rheological properties of the slurry is crucial to improve consistency in film formation during coating and drying, and to reduce slurry diffusion. This further helps to suppress misalignment caused by film layer deformation.

[0010] Studies have shown that small particles in the film coating slurry have a significant influence on its rheological behavior. Small particles do not settle as readily, which contributes to improved slurry stability. The colloid formed by their agglomeration increases the initial viscosity and disperses under shear stress, exhibiting shear thinning behavior. After the shear stress is removed, the small particles exhibit corresponding thixotropy and re-agglomerate into a colloid, helping to quickly restore viscosity and limit transition diffusion of the slurry. However, if too many small particles are present in the slurry, it can cause gelation, resulting in excessively high viscosity and impairing the coating process.Furthermore, the roundness of the particles also significantly influences the rheological behavior of the slurry. The colloid formed from highly spherical particles is more easily dispersed under shear stress, which helps to improve its shear thinning properties and the flowability of the slurry. In an embodiment of the present application, the area fraction of the particles with a particle size R1 that meets the condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35% of the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell. A50 of the cumulative distribution curve of the particle sphericity area 0.6 to 0.8, which contributes to achieving good shear thinning properties and suitable thixotropy of the cathode slurry, this helps to reduce the difference in the thinned area of ​​the cathode film layer in the thick coated electrode foil, reduce alignment deviations, decrease the probability of current collector leakage, while simultaneously improving space utilization and reducing the probability of lithium precipitation on the anode side, thereby improving the volume energy density of the battery, taking into account both safety performance and cycle performance.

[0011] In some embodiments, the thickness H of the main body area on one side can be between 90 µm and 120 µm when the battery cell is in a fully discharged state. In some embodiments, the thickness H of the main body area on one side can be between 100 µm and 120 µm when the battery cell is in a fully discharged state.

[0012] Increasing the thickness of the active cathode material layer increases the charge of the active substance and improves the battery's capacity. However, the applicant has found that the misalignment increases further with increasing one-sided thickness of the active cathode material layer, exacerbating the problems of current collector leakage and lithium precipitation, and further impairing the cycle performance and safety performance of the battery cell. In one embodiment of the present application, the battery cell comprises a laminated battery cell, wherein the laminated battery cell comprises a cathode foil, a separator, and an anode foil stacked one behind the other;wherein the cathode foil comprises a cathode current collector main body, a cathode tab and an active cathode material layer, wherein the active cathode material layer is arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, wherein the cathode tab is arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprises a main body region and a thinned region arranged on one side of the main body region facing the cathode tab, wherein the thickness of the thinned region is less than that of the main body region; wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles provided with a carbon material on at least a part of their surface;wherein the one-sided thickness H of the main body region is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the L is; A 50 of the cumulative distribution curve of the sphericity area of ​​the particles 0.6 to 0.8, which helps to further improve the capacity of the battery cell while reducing the probability of current collector leakage and lithium precipitation, achieving a balance between energy density, cycle performance and safety performance of the battery cells.

[0013] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.65 to 0.75.

[0014] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.67 to 0.72.

[0015] The sphericity of the particles in the active cathode material layer remains within the aforementioned range, which helps to further reduce alignment deviations and decrease the risk of current collector leakage and lithium precipitation, thereby further improving cycle performance and safety performance based on an increase in the energy density of the battery cells.

[0016] In some embodiments, it is provided that the projections of the edges of the two thinned areas facing away from the main body area on both sides of the cathode current collector main body are A and B respectively in the thickness direction of the battery cell, wherein the minimum distance E between A and B is 0.1 mm to 0.6 mm.

[0017] In one embodiment of the present application, the one-sided thickness H of the main body region is 70 µm to 120 µm; wherein, with respect to the total area of ​​the particles in the cross-sectional area of ​​the main body region along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35.0%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A50 in a cumulative distribution curve of the particle sphericity area is 0.6 to 0.8; which helps to improve the consistency of the dilute region and reduce the alignment deviation to the aforementioned region, thereby improving the capacity of the battery cell while reducing the probability of current collector leakage and lithium precipitation, taking into account both the cycle performance and the safety performance of the battery cell.

[0018] In some embodiments, it is provided that the projections of the edges of the two thinned areas facing away from the main body area on both sides of the cathode current collector main body in the thickness direction of the battery cell onto the cathode current collector main body are A and B respectively, wherein the minimum distance E between A and B is 0.1 mm to 0.4 mm.

[0019] In one embodiment of the present application, the alignment deviation lies further within the aforementioned range, which helps to further reduce the probability of current collector leakage and lithium precipitation and to improve the cycle performance and safety performance of the battery cell.

[0020] In some embodiments, it is provided that, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is 12% to 30%.

[0021] The uniformity of the slurry significantly influences its shear thinning properties and thixotropy. The applicant found that large particles with a particle size R2 that meets the condition R2 ≥ 1000 nm tend to sediment in the cathode slurry, thereby impairing the uniformity of the slurry. In one embodiment of the present application, the area fraction of particles with a particle size R2 that meets the condition R2 ≥ 1000 nm lies within the aforementioned range, which contributes to increasing the compaction density of the film layer and thus to increasing the battery capacity.On the other hand, the particle fraction is not too high, which helps to ensure the uniformity of the slurry, so that the slurry has good shear thinning properties and corresponding thixotropy, thereby reducing alignment deviation and simultaneously increasing battery capacity, reducing the probability of current collector leakage and lithium precipitation, and ensuring good cycle performance and safety performance.

[0022] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the uniformity of the distribution of particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is less than or equal to 5.0%.

[0023] In the active cathode material layer, the uniformity of the distribution of particles with a particle size R2, which fulfills a condition R2 ≥ 1000 nm, lies within the aforementioned range, indicating that they are uniformly distributed in the cathode slurry, i.e., the slurry exhibits good uniformity, which contributes to good shear thinning properties and suitable thixotropy, thereby reducing alignment deviations, decreasing the probability of current collector leakage and lithium precipitation, and further improving the cycle performance and safety performance of the battery cell.

[0024] In some embodiments, the uniformity of particle distribution in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, where R2 meets the condition R2 ≥ 1000 nm, is between 0.2% and 2.5%.In the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the uniformity of the distribution of particles with a particle size R2, which meets a condition R2 ≥ 1000 nm, lies in the range of 0.2% to 2.5% and beyond in the range of 0.2% to 2%, which helps to further reduce the alignment deviation and reduce the probability of current collector leakage and lithium precipitation, thereby further improving the cycle performance and safety performance of the battery.

[0025] In some embodiments, the active cathode material layer further comprises a binder, wherein the binder comprises a dispersant, wherein the dispersant comprises hydrogenated nitrile rubber HNBR.

[0026] HNBR is obtained by hydrogenating nitrile rubber to saturate the double bonds. Its highly saturated main chain structure gives it excellent oil resistance, heat resistance, and aging resistance, among other properties. This makes it stable when used as a dispersant in various environments and systems, so it is less likely to degrade or decompose and can thus effectively exert its dispersing effect. The HNBR molecular chain contains both polar nitrile groups and nonpolar hydrocarbon chain segments.Polar nitrile groups can interact with some polar substances or the surfaces of the particles, for example, by adsorption onto the surface of dispersed particles through hydrogen bonding, electrostatic interactions, or the like. The nonpolar hydrocarbon chain segments exhibit good lipophilicity and can stretch and disperse well in nonpolar or weakly polar media, thus distributing the particles evenly throughout the medium. When HNBR is adsorbed onto the surface of the particles in the slurry, its long-chain molecules form a physical barrier around the particles, preventing them from approaching and aggregating, and thus keeping the particles in a relatively independent dispersed state within the system.Simultaneously, HNBR can reduce the surface tension between the dispersion medium and the dispersed particles, thereby facilitating wetting of the particles by the medium and promoting particle dispersion within the medium. It can also reduce the interfacial energy between the particles, thus decreasing interfacial energy-driven particle aggregation and improving the uniformity of the slurry. In an embodiment of the present application, the active cathode material layer comprises hydrogenated nitrile rubber HNBR as a dispersant, which contributes to improving the uniformity of the slurry. This further reduces misalignment, decreases the risk of current collector leakage and lithium precipitation, and improves the capacity of the battery cells, while simultaneously ensuring good cycle performance and safety.

[0027] In some embodiments, the mass content of the dispersing agent is provided to be 0.5% to 2% in relation to the total mass of the active cathode material layer.

[0028] The mass fraction of the dispersant is within the aforementioned range, which helps to improve the uniformity of the slurry, further reduce alignment deviations, decrease the risk of current collector leakage and lithium precipitation, and improve the battery cell capacity, while also taking into account good cycle performance and safety performance.

[0029] In some embodiments, the active cathode material layer also comprises a conductive agent, wherein, with respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of an agglomerated region of the conductive agent is 0.5% to 2.5%.

[0030] With respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the agglomerated region of the conductive medium lies within the above range, which on the one hand shows that the cathode slurry has good uniformity, which helps to reduce alignment deviations and decrease the risk of current collector leakage and lithium precipitation, thereby improving the capacity of the battery cell while achieving good cycle performance and safety performance;On the other hand, it is shown that the conductive medium in the active cathode material layer is uniformly distributed and can easily form a uniform conductive network, which is particularly advantageous in reducing the problem of kinetic degradation caused by the growth of the ion transfer path in the thick coating film layer, reducing the local polarization and even lithium precipitation problem caused by the battery during the cycling process, and further improving the battery's cycle life.

[0031] In some embodiments, the active cathode material layer also comprises a conductive agent, wherein, with respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of an agglomerated region of the conductive agent is 1.5% to 2.5%.

[0032] In one embodiment of the present application, the area fraction of the agglomerated region of the conductive agent lies further within the above range, indicating that the conductive agent is more uniformly distributed in the active cathode material layer, and the content of the conductive agent is low, which helps to reduce the space occupied by the active cathode material due to an excessive conductive agent, thereby giving the battery good cycle performance, safety performance, dynamic properties and volume energy density.

[0033] In some embodiments, the conductive medium comprises a carbon nanotube, which includes one or more single-walled carbon nanotubes, thin-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0034] Since the carbon nanotube has a one-dimensional structure, it can form a network structure within the active cathode material layer. On the one hand, this network structure helps to distribute the particles in the slurry, improve the slurry uniformity, reduce alignment deviations, decrease the risk of current collector leakage and lithium precipitation, and further improve the battery's capacity while ensuring good cycle performance and safety. On the other hand, the excellent electrical conductivity of the carbon nanotube makes its network structure an efficient electron transfer channel, which helps to increase the electron transfer rate of thickly coated electrode foil in the thickness direction and improve the battery's dynamic properties.

[0035] In some embodiments, the conductive medium also includes conductive carbon black.

[0036] In some embodiments, the agglomerated area of ​​the conductive medium comprises the carbon nanotube and the conductive carbon black.

[0037] Researchers discovered that carbon nanotubes, due to their high surface energy, tend to agglomerate, leading to uneven distribution within their active cathode material layer and an inability to form an effective carbon nanotube network structure. The surface energies of conductive carbon black and carbon nanotubes are relatively close and can be adsorbed onto the surface of carbon nanotubes to form a physical barrier. This increases resistance to carbon nanotube agglomeration, reduces direct contact between carbon nanotubes, and thus prevents agglomeration and improves the uniformity of carbon nanotube distribution within the active cathode material layer.This contributes, on the one hand, to improving the electrical conductivity of the thickly coated active cathode material layer and increasing the battery's dynamic properties; on the other hand, it helps to utilize the three-dimensional network structure of the carbon nanotube to distribute the particles in the active cathode material layer, reduce misalignment, and further improve the battery's capacity, cycle life, and safety performance. Furthermore, the agglomeration of carbon nanotubes in the agglomerated region of the conductive medium also blocks local ion transfer pathways within this region, and the combination with conductive carbon black can improve the lithium-ion transfer capacity of this region, reduce local polarization, and further enhance the battery's cycle stability.

[0038] In some embodiments, it is provided that, with respect to the total mass of the active cathode material layer, the mass content C1 of the carbon nanotube is 0 <C1≤2,5% erfüllt, und der Massengehalt C2 des leitfähigen Rußes erfüllt 0<C2≤2,5%.

[0039] The mass content of carbon nanotubes and conductive carbon black is within the aforementioned range, which effectively mitigates the agglomeration of carbon nanotubes and forms a good conductive network structure, thereby reducing alignment deviations, increasing battery capacity, and taking into account both cycle performance and safety performance.

[0040] In some embodiments, the one-sided areal density of the active cathode material layer is 0.25 g / 1540.25 mm². 2 up to 0.45 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0041] In some embodiments, the one-sided areal density of the active cathode material layer is 0.3 g / 1540.25 mm². 2 up to 0.45 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0042] In some embodiments, the one-sided areal density of the active cathode material layer is 0.35 g / 1540.25 mm². 2 up to 0.4 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0043] If the one-sided coating area density of the active cathode material layer remains within the above range, this contributes to a further improvement in the battery's capacity. However, as the charge increases, the thickness of the active cathode material layer also increases accordingly. This triggers transition diffusion of the active cathode material layer during the coating-to-drying process, leading to misalignment. This, in turn, causes current collector leakage and lithium precipitation on the anode side, negatively impacting the energy density, cycle life, and safety performance of the battery cell.Therefore, in one embodiment of the present application, the one-sided thickness H of the main body region is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L. A50 in a cumulative distribution curve of the particle sphericity area is 0.6 to 0.8; it is particularly suitable for battery cells with a one-sided areal density of the active cathode material layer within the above-mentioned range, which helps to achieve a balance between energy density, cycle performance and safety performance of the battery cells.

[0044] In some embodiments, the density of the cathode foil is specified as 2.3 g / cm³. 3 up to 2.6 g / cm³ 3 is the value when the battery cell is in a completely discharged state.

[0045] A high compaction density contributes to increasing the volume energy density of the battery; a low compaction density reduces the porosity of the electrode foil and the liquid retention rate, which affects the transfer efficiency of lithium ions and thus the cycle performance and dynamic properties of the battery. In an embodiment of the present application, the compaction density of the cathode foil lies within the aforementioned range, which helps to achieve a balance between the energy density, cycle performance, and dynamic properties of the battery.

[0046] In some embodiments, the active cathode material layer further comprises an insulating layer located on a side of the thinned area facing away from the main body area.

[0047] In one embodiment of the present application, the burrs on the edge of the electrode foil pierce the separator, causing the cathode and anode to overlap and resulting in self-discharge or short circuit of the battery. On the side of the thinned area facing away from the main body area, an insulating layer is applied, which helps to reduce the overlap of the cathode and anode caused by burrs on the edge of the electrode foil and thus improve the cycle life and safety performance of the battery cell.

[0048] In some embodiments, the insulating layer is provided for to comprise a metal oxide.

[0049] In some embodiments, the metal oxide is provided to comprise one or more of aluminium oxide, zirconium oxide, magnesium oxide and titanium oxide.

[0050] 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; wherein, in the thickness direction of the battery cell, the edge of the projection of the anode film layer lies on the outside of the insulating layer.

[0051] The thickly coated electrode foil expands and deforms more during the cycling process, further reducing the size difference between the anode film layer and the active cathode material layer; in the thickness direction of the battery cell, the edge of the projection of the anode film layer falls onto the outside of the insulating layer, i.e., the size of the anode film layer exceeds that of the active cathode material layer, thus providing sufficient sites on the anode side for the embedding of lithium ions and reducing the risk of lithium precipitation on the anode side.

[0052] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the longitudinal direction of the battery cell is 4 mm to 16 mm.

[0053] The size of the anode film layer and the active cathode material layer in the longitudinal direction is within the aforementioned range, which helps to provide sufficient sites for embedding lithium ions at the edge of the anode foil in the longitudinal direction, reducing the probability of lithium precipitation on the anode side and thus improving the cycle life of the battery.

[0054] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the width direction of the battery cell is 1 mm to 5 mm.

[0055] The size of the anode film layer and the active cathode material layer in the lateral direction is within the aforementioned range, which helps to provide sufficient sites for embedding lithium ions at the edge of the anode foil in the lateral direction, reducing the probability of lithium precipitation on the anode side and thus improving the cycle life of the battery.

[0056] In some embodiments, the cathode tab is provided at at least one end of the cathode current collector main body, which extends along the longitudinal direction of the battery cell.

[0057] The cathode tab is provided at at least one end of the cathode current collector main body, which extends along the longitudinal direction of the battery cell, i.e., the tab is connected to the short side of the main body of the cathode current collector main body. This structure helps to reduce the volume of the insulating layer between the tab and the active cathode layer, decrease the volume occupied by inactive material on the cathode foil, and increase the charge of the active substance, which helps to increase the volume energy density of the battery cell.

[0058] In some embodiments, the cathode tab is provided at at least one end of the cathode current collector main body, which extends along the width direction of the battery cell.

[0059] The cathode tab is provided at at least one end of the cathode current collector main body, which extends along the width direction of the battery cell; that is, the long side of the tab is connected to the main body of the cathode current collector, thereby increasing the connection size between the tab and the main body of the current collector. This facilitates the processing of the tab and improves production efficiency, and also helps to increase the flow area at the connection between the current collector and the tab, reduce the internal resistance, and reduce the heat generation of the electrode foil.

[0060] In some embodiments, the separator comprises a base film, a ceramic layer arranged on at least one side of the base film, and an adhesive layer arranged on a side of the ceramic layer facing away from the base film on at least one side; the adhesive layer is a continuous layer with a porous structure, and the adhesive layer 203 comprises a vinylidene fluoride polymer.

[0061] In the prior art, the adhesive layer of the separator typically consists of water-based PVDF, resulting in an island structure within the separator. This is advantageous in order to provide gaps for the expansion of the battery cell and also simplifies manufacturing; however, the contact area between the adhesive layer of the separator and the electrode foil is small and the adhesive strength is weak.

[0062] The separator provided by an embodiment of the present application uses a continuous layer with a porous structure as an adhesive layer, and its porous structure provides space for the expansion of thick-coated battery cells, which helps to reduce the compression of the size difference between the anode film layer and the active cathode material layer by the thick-coated electrode foil, so that there are sufficient sites on the anode side for lithium deposition, thereby reducing the likelihood of lithium precipitation;Furthermore, in the prior art, the adhesive layer has a small contact area with the electrode foil and a weak adhesive strength, which can lead to a relative displacement between the adhesive layer and the active cathode material layer when the active cathode material layer rebounds, thereby further reducing the size difference between the anode and the cathode, increasing the probability of lithium precipitation and even causing a short circuit between the cathode and the anode, which impairs the safety performance of the battery;Furthermore, the extrusion between the separator and the electrode foil in the laminated battery cell is lower, and there is a higher probability of relative displacement between the separator and the electrode foil; therefore, the bonding between the separator and the electrode foil in embodiments of the present application is stronger and more uniform, which helps to reduce the risk of relative displacement between the separator and the electrode foil, further reduce the probability of lithium precipitation, and improve the safety performance of the battery.

[0063] In some embodiments, the thickness of the base film in the separator is provided to be 7 µm to 9 µm.

[0064] In some embodiments, the thickness of the ceramic layer on one side of the separator is 2 µm to 4 µm.

[0065] In some embodiments, the thickness of the adhesive layer on one side of the separator is 1 µm to 5 µm.

[0066] The thickness of the adhesive layer is too small, the space in the gap in the separator is too small, and the adhesive strength between the separator and the electrode foil is insufficient. On the one hand, after the film layer expands, the size difference between the anode and the cathode decreases, increasing the risk of lithium precipitation; on the other hand, the probability of a short circuit between the cathode and anode due to overlap increases, negatively impacting the battery's safety performance. If the thickness of the adhesive layer is too great, it occupies a large amount of space in the battery, thereby impairing the battery's volumetric energy density. In one embodiment of the present application, the thickness of the adhesive layer is within the aforementioned range, which helps to simultaneously consider the battery's cycle life, safety performance, and volumetric energy density.

[0067] In some embodiments, the active cathode material layer is provided with a lower coating in a lower region facing the cathode current collector, and the lower coating comprises a conductive agent and a binder, the conductive agent comprising a carbon nanotube and conductive carbon black, the binder comprising polyvinylidene fluoride (PVDF).

[0068] In some embodiments, the thickness of the lower coating is provided for to be 0.5 µm to 5 µm.

[0069] In comparison to direct contact between the cathode current collector and the active cathode material layer, the contact area between the lower coating and the active cathode material layer is increased, which helps to increase the area of ​​electron transfer between the current collector and the active cathode material layer, thereby reducing the internal resistance of the electrode foil and improving the dynamic properties of the battery.

[0070] In some embodiments, the cathode foil and the anode foil are stacked alternately along the thickness direction of the battery cell; the separator forms a continuous spiral structure or a continuous Z-shaped structure, wherein the separator is arranged to pass through between the cathode foil and the anode foil, which are adjacent to each other, in order to separate the cathode foil and the anode foil, which are adjacent to each other.

[0071] The separator in the battery cell is a continuous piece arranged in a spiral or Z-shape within the cathode foil and the anode foil. The separator has a certain position-limiting effect on the cathode foil and the anode foil, thus helping to reduce the risk of relative displacement between the cathode foil and the anode foil and to improve the safety performance and cycle performance of the battery.

[0072] In some embodiments, the battery cell also includes a shell in which the laminated battery cell is received, and the shell material is a soft packaging material, and the soft packaging material comprises an aluminum-plastic composite film.

[0073] In some embodiments, the shell material comprises a composite film of aluminum and one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), or polyethylene (PE).

[0074] The soft packaging material exhibits high elongation, allowing its shell to be thinner and softer, which contributes to better space utilization within the battery cell and thus increases the battery cell's energy density. Furthermore, the high barrier properties of aluminum effectively reduce the penetration of water and oxygen into the battery's interior, decrease electrolyte degradation and the oxidation level of the electrode material, and thus extend the battery's lifespan.

[0075] In some embodiments, the battery cell comprises a shell in which the laminated battery cell is received, wherein the size of the shell in the longitudinal direction is L1, the size of the shell in the width direction is W1, and the size of the shell in the thickness direction is H1, where 450 mm ≤ L1 ≤ 1300 mm, 100 mm ≤ W1 ≤ 150 mm; where 14 mm ≤ H1 ≤ 22 mm.

[0076] In some embodiments, the size of the shell in the longitudinal direction is L1, where 450 mm ≤ L1 ≤ 650 mm.

[0077] If the shell size in the longitudinal direction L1 meets the condition L1 ≤ 450 mm ≤ L1 ≤ 650 mm, the battery cell length is shorter, which helps to shorten the current diffusion path and reduce the internal resistance of the electrode foil, thereby reducing the heat generation of the battery and improving its dynamic properties; furthermore, the shorter shell length helps to shorten the diffusion path of the electrolyte solution during the wetting process, improve the wetting rate and uniformity of the electrolyte solution, further promote the uniformity of the deintercalation of lithium ions during the cycling process, and improve the cycle stability of the battery cell.

[0078] In some embodiments, the size of the shell in the longitudinal direction is L1, where 900mm ≤ L1 ≤ 1300mm.

[0079] If the shell dimensions in the longitudinal direction L1 ≤ 900 mm ≤ L1 ≤ 1300 mm, the battery cell is longer, which helps to reduce the volume fraction of the shell in the battery cell and increase the charge fraction of the active material. At the same time, a longer battery cell can reduce the number of batteries required in the battery module, simplify the structural design of the battery module, decrease the number and complexity of structural components in the module, and thus improve the space utilization of the battery pack and further contribute to improving the volume energy density of the battery cell.

[0080] In some embodiments, the lithium-containing transition metal phosphate particles are provided to comprise components that are represented by the following general formula: Li m Fe x P y O j Q q Formula 1 where Q comprises one or more of Al, Na, K, Mg, Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb, V, Ti, B, S, Si, N, F, Cl, Br, where 0.8 ≤ m ≤ 1.15, 0.9 ≤ x ≤ 1, 0.95 ≤ y ≤ 1, 3.5 ≤ j ≤ 4, 0 < q ≤ 0.1.

[0081] The second aspect of the present application provides a battery device comprising the battery cell provided in the first aspect of the present application.

[0082] In some embodiments, the battery device further comprises a housing, wherein several battery cells are stacked in a row along the thickness direction and glued into the housing; wherein a reinforcing partition plate is provided between the large surfaces of the shells of two adjacent battery cells, wherein the reinforcing partition plate is connected to the housing, and wherein the stiffness of the reinforcing partition plate is greater than the stiffness of the shell of the battery cell.

[0083] By providing and connecting the reinforcing partition plate to the housing, the reinforcing partition plate can be fixed so that the reinforcing partition plate can effectively support the battery cell, improve the stiffness of the battery cell and thus improve the stiffness of the entire battery device.

[0084] In some embodiments, it is provided that two reinforcing separating plates, arranged side by side along the thickness direction and distributed on both sides of at least one battery cell in the thickness direction, are connected to each other by a connecting plate located in the outer circumferential region of the battery cell.

[0085] The connecting plate can be provided to improve the reliability of the support offered by the reinforcing separator plate of the battery cell.

[0086] In some embodiments, the connecting plate is arranged between the two reinforcing partition plates and integrally joined to them to form a U-shaped shell. The process of joining the connecting plate to the reinforcing partition plate can be omitted, and the reliability of the connection between the connecting plate and the reinforcing partition plate can be further improved.

[0087] A third aspect of the present application provides a power-consuming device comprising the battery device provided in the second aspect, and the battery device is used to provide electrical energy.

[0088] A fourth aspect of the present application provides an energy storage device comprising the battery device provided in the second aspect, and the battery device is used to store electrical energy. Description of the characters Fig. Figure 1 is a schematic representation of a cathode foil according to an embodiment of the present application; Fig. Figure 2 is a schematic representation of a separator according to an embodiment of the present application; Fig. Figure 3 is a schematic representation of a separator according to the state of the art; Fig. Figure 4 is a schematic representation of the surface morphology of an adhesive layer according to an embodiment of the present application; Fig. Figure 5 is a schematic representation of a battery device according to an embodiment of the present application; Fig. Figure 6 is a schematic representation of a power-consuming device according to an embodiment of the present application. Explanation of reference symbols: 1 cathode foil; 11 active cathode substance layer; 111 Main body area; 112 diluted area; 121 Cathode current collector main body; 122 Cathode tab; 13 Insulating layer; X Longitude direction; Y Latitude direction; Z Thickness direction; 20 Separator; 201 Basic film; 202 Ceramic layer; 203 Adhesive layer; 30 battery cells; 40 reinforcing separating plate; 50 connecting plates. Detailed description

[0089] The following sections describe and disclose in detail embodiments of the battery cell, battery device, current-consuming device, and energy storage device of the present application 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 avoided. This is to prevent the following description from becoming unnecessarily long and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description serve to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0090] The “ranges” disclosed in this application are defined in terms of a lower bound and an upper bound. A particular range is defined by selecting a lower bound and an upper bound, and the selected lower bound and upper bound define the limits of the respective range. The range thus defined may include or exclude the upper bounds and can be combined arbitrarily; that is, any lower bound can be combined with any upper bound to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, 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 the present application, unless otherwise specified, the number range "a to b" represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the 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.

[0091] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form a new technical solution, and such technical solutions should be considered to be contained within the disclosure of this application.

[0092] Unless otherwise stated, all technical features and optional technical features of the present application may be combined to form a new technical solution, and such technical solutions should be considered to be contained within the disclosure content of this application.

[0093] Unless otherwise stated, all steps of the present application may be carried out sequentially or in any order, but preferably sequentially. For example, if a method comprises steps (a) and (b), this means that the method may include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially. For example, if it is mentioned that the method may also include step (c), this means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), or the like.

[0094] In this application, the terms "several" and "multiple" refer to two or more. Unless otherwise specified, the terms used in this application have the generally understood meanings that are usually accorded to those skilled in the art in this field.

[0095] Unless otherwise specified, the numerical values ​​of the parameters mentioned in the present application can be measured by various test methods commonly used in this field; for example, they can be measured according to the test methods specified in the embodiments of the present application. Unless otherwise specified, all parameters are tested at 25 °C.

[0096] In one embodiment of the present application, a battery device can comprise one or more battery cell assemblies to provide voltage and capacity. A battery cell assembly can comprise multiple softpack battery cells connected in series, parallel, or a mixed configuration via a bus component. For example, a battery cell assembly is typically formed by arranging multiple softpack battery cells; the battery cell assembly can be a battery module formed by arranging and securing the multiple softpack battery cells in an independent module. For example, a battery module can be formed by bundling multiple battery cells with cable ties.

[0097] The battery device can be a battery pack comprising a housing and one or more battery cell assemblies contained within the housing. The battery cell assembly can be a battery module, and the battery cell assembly can be contained within the housing by attaching the battery module to the housing; alternatively, the battery cell assembly can be contained within the housing by attaching several softpack battery cells directly to the housing.

[0098] In one embodiment of the present application, the housing can comprise a first housing and a second housing. The first housing and the second housing are snapped together, so that the interior of the housing forms a sealed space for receiving the battery cell arrangement. "Sealed" here means "covered" or "closed" and can be sealed or unsealed. The first housing can be a top cover or a bottom plate. For example, the housing can comprise a top cover, a frame, and a bottom plate. The top cover and the bottom plate are each connected to the frame, so that the interior of the housing forms a sealed space for receiving the battery cell arrangement.

[0099] In the embodiments described in the present application, the housing can be designed 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.

[0100] In one embodiment of the present application, the battery cell may be a secondary battery, meaning a battery cell that can be recharged after discharge to activate the active material and then reused; the battery cell may be a lithium-ion battery. The battery cell may be a flat body.

[0101] The battery mentioned in the embodiments of the present application can be a single physical module comprising one or more battery cells to provide a higher voltage and capacity. For example, the battery mentioned in this application can comprise a battery cell, a battery module, a battery pack, or the like.

[0102] A battery cell is the smallest unit of a battery and can perform the charging and discharging functions independently of each other.

[0103] In the case of multiple battery cells, the multiple battery cells are connected via a bus component in series, parallel, or a mixed configuration. In some embodiments, the battery can be a battery module; in the case of multiple battery cells, the multiple battery cells are arranged and secured to form a battery module. In some embodiments, the battery can be a battery pack comprising a housing and a battery cell, with the battery cell or battery module being contained within the housing.

[0104] In some embodiments, the housing can be designed as part of the vehicle's chassis structure. For example, part of the housing can become at least part of a floor panel of the vehicle, or part of the housing can become at least part of a cross member and a longitudinal member of the vehicle.

[0105] In some embodiments, the battery can be an energy storage device. The energy storage device includes, for example, an energy storage container, an energy storage cabinet, and the like.

[0106] In some embodiments, it is provided that the battery cells can be assembled into a battery module, several battery cells can be contained in one battery module, and the specific number can be adjusted based on the application and capacity of the battery module.

[0107] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted depending on the application and capacity of the battery pack.

[0108] A battery cell comprises an electrode array and an electrolyte.

[0109] The electrode arrangement typically includes a cathode foil and an anode foil, and the anode foil is an electrode that absorbs or lithiates lithium ions during charging and releases or delithiates lithium during discharging, and the cathode foil is an electrode that releases or delithiates lithium ions during charging and absorbs or lithiates lithium during discharging.

[0110] Lithium-containing transition metal phosphate exhibits good thermal stability and cycle performance and is frequently used as the active cathode material in batteries. However, its gram capacity is relatively low compared to a ternary material. To increase the energy density of battery cells, the following solutions are commonly employed in the prior art: to increase the charge per unit area in the active cathode material layer, a thick coating strategy is used, while laminated battery cells are employed to improve space utilization within the battery. However, the applicant noted that this solution faces new technical problems, and the thick coating strategy easily leads to large misalignments of the active cathode material layer on both sides of the electrode foil, as shown in [reference]. Fig. Figure 1 shows this. On the one hand, this exposes the cathode current collector at the edge of the film layer, leading to a reduction in the average charge per unit area at the cathode foil and affecting the energy density of the battery cell. On the other hand, the misalignment reduces the size difference between the anode film layer and the active cathode material layer, leading to lithium precipitation on the anode side. However, in the thick-coated laminated battery cell, greater volume expansion and stress occur during the cycling process, and the active cathode material layer deforms under the influence of the stress. This further reduces the size difference between the anode and cathode foils, exacerbating the lithium precipitation phenomenon on the anode side and impairing the battery's safety performance and cycle stability.Therefore, the question of how to provide a battery with high energy density, good cycle performance and safety has become a technical problem that urgently needs to be solved in this field.

[0111] To solve the aforementioned problems, the present application provides a battery cell comprising a laminated battery cell, wherein the laminated battery cell comprises a cathode foil 1, a separator and an anode foil stacked one behind the other; wherein the cathode foil 1 comprises a cathode current collector main body 121, a cathode tab 122 and an active cathode material layer 11, wherein the active cathode material layer 111 is arranged on both sides of the cathode current collector main body 121 along the thickness direction Z of the battery cell, and wherein the cathode tab 122 is arranged on at least one side of the cathode current collector main body 121;The active cathode material layer 11 comprises a main body region 111 and a thinned region 112, which is arranged on one side of the main body region 111 facing the cathode tab 122, wherein the thickness of the thinned region 112 is less than the thickness of the main body region 111; wherein the active cathode material layer 11 comprises an active cathode material, the active cathode material comprising lithium-containing transition metal phosphate particles that are provided with a carbon material on at least part of their surface; wherein the one-sided thickness H of the active cathode material layer 11 is 70 µm to 120 µm when the battery cell is in a fully discharged state;wherein, with reference to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer 11 along the thickness direction Z of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; wherein in a cross-sectional area of ​​the active cathode material layer 11 along the thickness direction Z of the battery cell L; A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.6 to 0.8.

[0112] The battery cells of the embodiments of the present application improve the problems of current collector leakage and lithium precipitation and take into account both cycle life and safety performance while maintaining high capacity.

[0113] Without being bound to any theory, this could be due to the following reasons: by using a laminated battery cell structure, the presence of invalid space within the battery cell can be reduced and the unavoidable corner gaps and interlayer gaps during the winding process can be effectively eliminated, thus making the entire battery cell structure more compact, thereby improving space utilization, increasing the volume energy density of the battery cell and increasing the battery capacity; furthermore, the one-sided thickness H of the main body area is in the range of 70 µm to 120 µm, with a higher charge of active substance, thereby further improving the energy density of the battery.

[0114] Furthermore, the slurry forming the battery film layer is a non-Newtonian fluid with rheological properties, including shear thinning and thixotropy. During coating, the viscosity of the slurry decreases significantly under shear stress (shear thinning), which helps to reduce coating resistance and achieve good surface smoothness. After coating, the viscosity of the slurry gradually recovers (thixotropy) when the shear stress is removed, forming a thinner zone. Appropriate thixotropy helps to prevent lateral diffusion of the slurry after coating and improves the dimensional stability of the thinner zone at the coating interface. During thick coating processes, the unidirectional areal density of the slurry increases.Under the influence of gravity, the diluted area at the edge tends to distribute unevenly, leading to misalignment. Therefore, optimizing the rheological properties of the slurry is crucial to improve consistency in film formation during coating and drying, and to reduce slurry diffusion. This helps to further suppress misalignment caused by film layer deformation. Studies have shown that small particles in the film layer slurry have a significant impact on its rheological behavior.Small particles do not settle as easily, which contributes to improved slurry stability. The colloid formed by their agglomeration increases the initial viscosity and disperses under shear stress, exhibiting shear thinning behavior. After the shear stress is removed, it displays a corresponding thixotropy, and the small particles re-agglomerate into a colloid. This helps to quickly restore viscosity and limit transition diffusion of the slurry. However, if there are too many small particles in the slurry, it can gel, resulting in excessive viscosity and impairing the coating process.Furthermore, the roundness of the particles also significantly influences the rheological behavior of the slurry. The colloid formed from highly spherical particles is more easily dispersed under shear stress, which helps to improve its shear thinning properties and the flowability of the slurry. In an embodiment of the present application, the area fraction of the particles with a particle size R1 that meets the condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35% of the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell. A50 of the cumulative distribution curve of the particle sphericity area 0.6 to 0.8, which contributes to achieving good shear thinning properties and suitable thixotropy of the cathode slurry, this helps to reduce the difference in the thinned area of ​​the cathode film layer in the thick coated electrode foil, reduce alignment deviations, decrease the probability of current collector leakage, while simultaneously improving space utilization and reducing the probability of lithium precipitation on the anode side, thereby improving the volume energy density of the battery, taking into account both safety performance and cycle performance.

[0115] In the present application, a laminated battery cell refers to a battery cell formed by stacking a cathode foil, a separator and an anode foil.

[0116] In the present application, the thickness direction of the battery cell refers to the stacking direction of the cathode foil, the separator and the anode foil and is also the thickness direction of the cathode foil and the anode foil.

[0117] The lithium-containing transition metal phosphate in the present application refers to a phosphate material containing lithium and a transition metal element, which can be detected by all methods known in the art. For example, it can be detected by combining an X-ray diffractometer (XRD) with an energy spectrum analyzer and an inductively coupled plasma mass spectrometer.

[0118] The carbon material arranged on at least a part of the surface of the lithium-containing transition metal phosphate particles can be detected in the present application using all methods known in this field. For example, by characterizing the lithium-containing transition metal phosphate particles using a coupling of a transmission electron microscope and an energy spectrum analyzer, it is possible to observe the carbon material arranged on at least a part of the surface of the lithium-containing transition metal phosphate particles.

[0119] It is understood that the thinned area is present at least on one side facing the cathode tab. After coating and drying the active cathode material layer, the cathode foil is trimmed according to its polarity to preserve the cathode tab. Therefore, when the slurry is coated, an uncoated area remains exposed, with the tab position on the cathode current collector exposed. During the coating-to-drying process, the slurry diffuses into the edge reserve area, forming a thinned area with a gradual thickness transition. The formation of this thinned area is closely related to the rheological behavior of the slurry. Generally, the thickness decreases gradually from its junction with the main body area to the edge near the tab; that is, the thickness of the thinned area is less than the thickness of the main body area.

[0120] In the present application, the fully discharged state refers to the state in which the battery is placed in an oven environment at 25 °C and left for 2 hours, discharging the battery with a constant current of 1 / 3C to 2.5 V and subsequently with a constant current of 0.1C to 2.0 V, while maintaining a constant battery temperature of 25 °C.

[0121] The thickness of the main body region can be measured using all methods known in this field. For example, the thickness of the main body region of the cathode foil is measured in a cross-section along the thickness direction using a scanning electron microscope.

[0122] In some embodiments, the one-sided thickness H of the main body area is specified as 70 µm, 71 µm, 72 µm, 73 µm, 74 µm, 75 µm, 76 µm, 77 µm, 78 µm, 79 µm, 80 µm, 81 µm, 82 µm, 83 µm, 84 µm, 85 µm, 86 µm, 87 µm, 88 µm, 89 µm, 90 µm, 91 µm, 92 µm, 93 µm, 94 µm, 95 µm, 96 µm, 97 µm, 98 µm, 99 µm, 100 µm, 101 µm µm, 102 µm, 103 µm, 104 µm, 105 µm, 106 µm, 107 µm, 108 µm, 109 µm, 110 µm, 111 µm, 112 µm, 113 µm, 114 µm, 115 µm, 116 µm, 117 µm, 118 µm, 119 µm, 120 µm or a numerical range between any two values ​​can be selected when the battery cell is in a fully discharged state.

[0123] In some embodiments, the thickness H of the main body area on one side can be between 90 µm and 120 µm when the battery cell is in a fully discharged state. In some embodiments, the thickness H of the main body area on one side can be between 100 µm and 120 µm when the battery cell is in a fully discharged state.

[0124] Increasing the thickness of the active cathode material layer increases the charge of the active substance and improves the battery's capacity. However, the applicant has found that the misalignment increases further with increasing one-sided thickness of the active cathode material layer, exacerbating the problems of current collector leakage and lithium precipitation, and further impairing the cycle performance and safety performance of the battery cell. In one embodiment of the present application, the battery cell comprises a laminated battery cell, wherein the laminated battery cell comprises a cathode foil, a separator, and an anode foil stacked one behind the other;wherein the cathode foil comprises a cathode current collector main body, a cathode tab and an active cathode material layer, wherein the active cathode material layer is arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, wherein the cathode tab is arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprises a main body region and a thinned region arranged on one side of the main body region facing the cathode tab, wherein the thickness of the thinned region is less than that of the main body region; wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles provided with a carbon material on at least a part of their surface;wherein the one-sided thickness H of the main body region is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the L is; A 50 of the cumulative distribution curve of the sphericity area of ​​the particles 0.6 to 0.8, which helps to further improve the capacity of the battery cell while reducing the probability of current collector leakage and lithium precipitation, achieving a balance between energy density, cycle performance and safety performance of the battery cells.

[0125] In the present application, the term "particle" refers to particles in the active cathode material layer whose complete boundaries are visible in the field of view at a certain magnification, for example, 10,000x. The particles may contain defects and scratches, but their interiors are not visible with sufficiently complete boundaries to allow segmentation. In the present application, the active cathode material layer can be either a newly produced active cathode material layer or one obtained by dismantling a battery.

[0126] In the present application, the active cathode material layer contains an active cathode material, but the active cathode material layer does not refer only to the active cathode material layer, with other film layers that are associated with the active cathode material layer and are difficult to distinguish, such as the bottom coating, the liquid retention layer and the like, being collectively referred to as the active cathode material layer.

[0127] In the present application, the particle detection method proceeds as follows: the active cathode material layer is cut along the thickness direction of the electrode foil by an argon ion beam (the following device can be used as an example: Leica EMTIC3XCP, operating voltage: 6 kV, operating time: 6 hours). After the cut surface has been exposed, a scanning electron microscope is used (the following can be selected as an example: instrument model: Hitachi SU8230, operating voltage: 3 kV, beam current: high, probe model: U (LA100), working distance < 5 mm).to observe the cross-sectional area of ​​the active cathode material layer along the thickness direction of the electrode foil. The image is acquired using a field emission scanning electron microscope in secondary electron mode at the non-edge position in the cross-sectional area of ​​the active cathode material layer (after observing the edge of the electrode foil under the scanning electron microscope, the field of view is adjusted to the center of the sample), whereby 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 procedure for using the ImageJ software is as follows: loading a scanning electron microscope image to be analyzed; detecting the particles with the plug-in software Cellpose;Based on this, a manual correction is performed; the data is read and analyzed using the ImageJ software. The specific method for particle detection using the Cellpose plug-in software is as follows: setting the "Segmentation Diameter" parameter (diameter in the "Segmentation" module) to 15 pixels, clicking "runcyto3" 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, resulting in them not being detected or only being detected incompletely; 2. Scratches are created on the particle surface during argon ion beam cutting, and during detection, the software may incorrectly interpret these scratches as particle boundaries.which leads 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 interior of the particles is penetrated by the edge, the morphology cannot be fully displayed, and the part is detected instead of the whole, leading to detection errors. For the aforementioned particles that are not detected or exhibit detection errors, manual calibration is performed, and the specific procedure is as follows: Deleting the large particles at the edges of the scanning electron microscope that cannot be fully displayed; Determining whether there are gaps or scratches within other particles that are not identified or exhibit detection errors, whereby if there are no gaps or scratches within a particle,It is identified as a single particle and manually marked based on 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, with the particles being divided along the boundary; Perform a contrast comparison in response to the linear shape of the slit or scratch; Determine, in response to an indistinct contrast comparison and the lack of a slit sensation, that the particle is a scratch.which is detected as a single particle; determining, in response to a strong contrast comparison and the slit sensation, that it is the boundary between particles that are detected 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. It is understood that the particles in the cross-section of the active cathode material 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 embodiments of the present application can accurately and objectively reproduce the distribution of the lithium-containing transition metal phosphate particles in the active cathode material layer.by observing and counting the particle area in the cross-sectional area of ​​the cathode foil in the thickness direction of the electrode foil.

[0128] In the prior art, a laser particle size analyzer is typically used to count the particle size of the active cathode material using the Malvern laser diffraction method. However, investigations by the applicant show that lithium-containing transition metal phosphate particles tend to agglomerate. Therefore, the test results obtained with the Malvern laser diffraction method, which is based on the laser scattering principle, often measure the particle size of the particle agglomerates. This means that the test results obtained with the Malvern laser diffraction method, which is based on the laser scattering principle, often measure the particle size of the particle agglomerates. This cannot accurately reflect either the particle size of the particle in the active cathode material or 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 increases during the slurry preparation and film rolling processes.The test results obtained using the Malvern laser diffraction method are influenced by the particle size, specific surface area, and degree of agglomeration of the active cathode material. Compared to the actual dispersion in the electrode foil, the number of large particles obtained by this test is lower than the actual value, and the number of small particles is higher than the actual value. Therefore, the particle size determined using the Malvern laser diffraction method cannot correspond to or be analogous with the particle size statistically determined in the embodiments of the present application.

[0129] The test procedure for the area fraction of particles with a particle size R1 that meets the condition 50 nm ≤ R1 ≤ 400 nm, based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, is specifically as follows: Referring to the above method of the present application, the particles in the cross-sectional area of ​​the active cathode material layer are detected. After particle detection and identification, the images are imported into the software ImageJ for analysis, and the scale is set according to the scanning electron microscope image. The particle size, area, sphericity, and roughness of the particles in the cross-sectional area of ​​the active cathode material layer along the battery cell direction are statistically analyzed using the analysis functions "Feret Diameter," "Area," "Round," and "Solidity."According to the software manual (ImageJUserGuideIJ 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. Particles with a diameter of less than 50 nm exhibit large errors in the statistical process and are difficult to detect accurately, and the particle size of the conductive medium is generally less than 50 nm, leading to large errors in the statistical results. Therefore, in the particle size statistics process of this application, particles with a size of less than 50 nm are not counted, and the particle statistics where AR, Round, or Solidity are displayed as "NaN" are discarded.The sum of the area parameters of particles whose particle size R1 satisfies the condition 50 nm ≤ R1 ≤ 400 nm, and the sum of the area parameters of all particles, are each calculated as the area of ​​particles whose particle size R1 satisfies the condition 50 nm ≤ R1 ≤ 400 nm, and as the total area of ​​the statistical particles. With respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles whose particle size R1 satisfies the condition 50 nm ≤ R1 ≤ 400 nm is calculated by dividing the sum of the areas of the particles whose particle size R1 satisfies the condition 50 nm ≤ R1 ≤ 400 nm by the total area of ​​the counted particles.

[0130] In some embodiments, the area fraction of particles whose particle size R1 meets the condition 50 nm ≤ R1 ≤ 400 nm, relative to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, is defined as 10%, 10.1%, 10.2%, 10.3%, 10.4%, 10.5%, 10.6%, 10.7%, 10.8%, 10.9%, 11.0%, 11.1%, 11.2%, 11.3%, 11.4%, 11.5%, 11.6%, 11.7%, 11.8%, 11.9%, 12.0%, 12.1%, 12.2%, 12.3%, 12.4%. 12.5%, 12.6%, 12.7%, 12.8%, 12.9%, 13.0%, 13.1%, 13.2%, 13.3%, 13.4%, 13.5%, 13.6%, 13.7%, 13.8%, 13.9%, 14.0%, 14.1%, 14.2%, 14.3%, 14.4%, 14.5%, 14.6%, 14.7%, 14.8%, 14.9%, 15.0%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27% 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% or a numerical range between any two values ​​can be selected.

[0131] In the present application, the test procedure for the sphericity of the particles in the cross-section of the active cathode material layer along the thickness direction of the battery cell is as follows: the particles in the cross-section of the active cathode material layer are identified with reference to the procedure described above in this application, and the morphology of the particles in the cross-section along the thickness direction of the battery cell in the active cathode material layer is analyzed using the "Shape Description" analysis function in ImageJ. According to the software manual (ImageJ User Guide IJ 1,46r), the "Round" parameter represents the ratio of the pixel area of ​​the particle to the area of ​​a circle with the adjusted long diameter as its diameter, which allows the sphericity of the particles to be characterized.The closer a particle is to a sphere, the closer the ratio of its pixel area to the area of ​​a circle with the adjusted long diameter as its diameter approaches 1. Therefore, the particle's "Round" parameter, obtained through analysis, is used to characterize its sphericity. The sphericity of at least 1000 particles is arranged in ascending order, and the cumulative distribution curve of particle sphericity in the active cathode material layer is obtained, with sphericity as the horizontal axis and cumulative area fraction as the vertical axis. L. A 50 is the sphericity L-value, which corresponds to the value at which the cumulative area fraction of the vertical axis in the cumulative distribution curve of the particle sphericity is 50%.

[0132] A person skilled in the art can adjust the sphericity of the particles through all known processes. For example, the sphericity of the particles can be adjusted through processes such as grinding, polishing, chemical etching, mechanical stirring, extrusion, coating, granulation, the addition of surfactants, and adjusting the parameters of each process.

[0133] In some embodiments, it is provided that in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in the cumulative distribution curve of the sphericity area of ​​the particles can be selected as 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.705, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8 or a numerical range between any two values.

[0134] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.65 to 0.75.

[0135] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.67 to 0.72.

[0136] The sphericity of the particles in the active cathode material layer remains within the aforementioned range, which helps to further reduce alignment deviations and decrease the risk of current collector leakage and lithium precipitation, thereby further improving cycle performance and safety performance based on an increase in the energy density of the battery cells.

[0137] It is available in some embodiments, such as in Fig. Figure 1 shows that the projections of the edges of the two thinned areas 112 facing away from the main body area on both sides of the cathode current collector main body 121 in the thickness direction Z of the battery cell onto the cathode current collector main body are A and B respectively, wherein the minimum distance E between A and B is 0.1 mm to 0.6 mm.

[0138] In the present application, the projections of the edges of the two thinned areas on both sides of the cathode current collector main body, facing away from the main body area, onto the cathode current collector main body in the thickness direction of the battery cell are A and B respectively, where the minimum distance E is the alignment deviation, as shown in Fig. Figure 1 shows a method that can be tested using a known procedure and instrument in this field. For example, the battery is disassembled to obtain the cathode foil, and the active cathode material layer is a black film layer. Visually, the active cathode material layers on both sides of the cathode current collector are identified, and the active cathode material layers are projected in the thickness direction of the battery cell to obtain A and B, using a high-precision micrometer (e.g., Mitutoyo 293-100, with an accuracy of 0.1 µm). Alternatively, the battery is disassembled to obtain the cathode foil, and the cathode foil is then sliced ​​parallel to the extension of the tab. A scanning electron microscope image is photographed at a point on the cathode foil facing the tab to distinguish the edges of the cathode film layer. Subsequently, the projections A and B are obtained and measured.

[0139] It is worth noting that the cathode foil in the present application can be freshly manufactured or disassembled from a battery.

[0140] In some embodiments, the projections of the edges of the two thinned areas facing away from the main body area on both sides of the cathode current collector main body onto the cathode current collector main body are A and B, respectively, in the thickness direction of the battery cell, with the minimum distance E between A and B being 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.20 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 mm, 0.31 mm, 0.32 mm, 0.33 mm. 0.34 mm, 0.35 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.40 mm, 0.41 mm, 0.42 mm, 0.43 mm, 0.44 mm, 0.45 mm, 0.46 mm, 0.47 mm, 0.48 mm, 0.49 mm, 0.50 mm, 0.51 mm, 0.52 mm, 0.53 mm, 0.54 mm, 0.55 mm, 0.56 mm, 0.57 mm, 0.58 mm, 0.59 mm, 0.6 mm or a numerical range between any two values ​​can be selected.

[0141] In one embodiment of the present application, the one-sided thickness H of the main body region is 70 µm to 120 µm; wherein, with respect to the total area of ​​the particles in the cross-sectional area of ​​the main body region along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A50 in a cumulative distribution curve of the particle sphericity area is 0.6 to 0.8; which helps to improve the consistency of the dilute region and reduce the alignment deviation to the aforementioned region, thereby improving the capacity of the battery cell while reducing the probability of current collector leakage and lithium precipitation, taking into account both the cycle performance and the safety performance of the battery cell.

[0142] In some embodiments, it is provided that the projections of the edges of the two thinned areas facing away from the main body area on both sides of the cathode current collector main body in the thickness direction of the battery cell onto the cathode current collector main body are A and B respectively, wherein the minimum distance E between A and B is 0.1 mm to 0.4 mm.

[0143] In one embodiment of the present application, the alignment deviation lies further within the aforementioned range, which helps to further reduce the probability of current collector leakage and lithium precipitation and to improve the cycle performance and safety performance of the battery cell.

[0144] In some embodiments, it is provided that, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is 12% to 30%.

[0145] In the present application, the area fraction of particles with a particle size R2 that meets the condition R2 ≥ 1000 nm, relative to the total area of ​​particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, can be measured using a method or instrument known in this field. For example, reference can be made to the test method described above for the area fraction of particles with a particle size R1 that meets the condition 50 nm ≤ R1 ≤ 400 nm, relative to the total area of ​​particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, to perform the measurement. The specific steps are: with reference to the above method of the present application, the particles in the cross-sectional area of ​​the active cathode material layer are detected.After particle determination and identification, the images are imported into the ImageJ software for analysis, and the scale is set according to the scanning electron microscope image. The particle size, area, sphericity, and roughness of the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the electrode foil are statistically analyzed using the analysis functions "Feret Diameter," "Area," "Round," and "Solidity." According to the software manual (ImageJUserGuideIJ 1.46r), the "Feret" parameter 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 "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, it is difficult to identify them accurately. Furthermore, the particle size of the conductive medium is generally less than 50 nm, leading to a large error in the statistical results. Therefore, in the particle size statistics process of this application, particles with a size of less than 50 nm are not counted, and the particle statistics where AR, Round, or Solidity are displayed as "NaN" are deleted. The sum of the "Area" parameters of particles whose particle size R2 satisfies the condition R2 ≥ 1000 nm, and the sum of the "Area" parameters of all particles, are calculated as the area of ​​particles whose particle size R2 satisfies the condition R2 ≥ 1000 nm and as the total area of ​​the statistical particles, respectively.With reference to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles whose particle size R2 meets a condition R2≥1000 nm is calculated by dividing the sum of the areas of the particles whose particle size R2 meets a condition R2≥1000 nm by the total area of ​​the counted particles.

[0146] In some embodiments, it is provided that, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles whose particle size R2 meets a condition R2≥1000 nm can be selected as 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% or a numerical range between any two values.

[0147] The uniformity of the slurry significantly influences its shear thinning properties and thixotropy. The applicant found that large particles with a particle size R2 that meets the condition R2 ≥ 1000 nm tend to sediment in the cathode slurry, thereby impairing the uniformity of the slurry. In one embodiment of the present application, the area fraction of particles with a particle size R2 that meets the condition R2 ≥ 1000 nm lies within the aforementioned range, which contributes to increasing the compaction density of the film layer and thus to increasing the battery capacity.On the other hand, the particle fraction is not too high, which helps to ensure the uniformity of the slurry, so that the slurry has good shear thinning properties and corresponding thixotropy, thereby reducing alignment deviation and simultaneously increasing battery capacity, reducing the probability of current collector leakage and lithium precipitation, and ensuring good cycle performance and safety performance.

[0148] In some embodiments, it is provided that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the uniformity of the distribution of particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is less than or equal to 5.0%.

[0149] In the present application, the uniformity of the distribution of particles with a particle size R2, satisfying a condition R2 ≥ 1000 nm, can be tested in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell using a method known in this field. For example, the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell is divided into three layers of equal thickness along the thickness direction (if the surface of the cathode current collector is coated with a bottom coating and then with the active cathode material layer, the area of ​​the active cathode material layer extending from a point 5 µm away from the cathode current collector is divided into three layers of equal thickness along the thickness direction).The surface of the active cathode material layer facing away from the cathode current collector is divided in the thickness direction of the electrode foil into three layers of equal thickness: a lower layer facing the cathode current collector, an upper layer facing away from the cathode current collector, and a middle layer located between the upper and lower layers. Ten non-overlapping fields of view are randomly selected in the upper, middle, and lower layers, and scanning electron microscope images are acquired at a magnification of 10k. The ten scanning electron microscope images acquired for each layer are imported into the ImageJ software for analysis. According to the aforementioned "test procedure for the area fraction of particles with a particle size R2 that satisfies a condition R2≥1000nm,"Based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fractions of particles with a particle size R2 that meet the condition R2 ≥ 1000 nm are determined in the 10 figures, each corresponding to the upper, middle, and lower layers, respectively. A total of three values ​​are obtained. The range value of the three values ​​for the upper, middle, and lower layers corresponds to the uniformity of the distribution of particles with a particle size R2 that meet the condition R2 ≥ 1000 nm in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, where the range value is the difference between the maximum and minimum values ​​of the upper, middle, and lower layers. The lower the uniformity of the distribution of particles with a particle size R2 that meet the condition R2 ≥ 1000 nm,The more uniform the distribution of large particles with a particle size R2 that meets the condition R2 ≥ 1000 nm in the active cathode material layer is in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell.

[0150] In some embodiments, the uniformity of the distribution of particles with a particle size R2, which fulfills a condition R2 ≥ 1000 nm, is provided for in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell as 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0% or a numerical range between any two values ​​can be selected.

[0151] In the active cathode material layer, the uniformity of the distribution of particles with a particle size R2, which fulfills a condition R2 ≥ 1000 nm, lies within the aforementioned range, indicating that they are uniformly distributed in the cathode slurry, i.e., the slurry exhibits good uniformity, which contributes to good shear thinning properties and suitable thixotropy, thereby reducing alignment deviations, decreasing the probability of current collector leakage and lithium precipitation, and further improving the cycle performance and safety performance of the battery cell.

[0152] In some embodiments, the uniformity of particle distribution in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, where R2 meets the condition R2 ≥ 1000 nm, is between 0.2% and 2.5%.

[0153] In the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the uniformity of the distribution of particles with a particle size R2, which meets a condition R2 ≥ 1000 nm, lies in the range of 0.2% to 2.5% and beyond in the range of 0.2% to 2%, which helps to further reduce the alignment deviation and reduce the probability of current collector leakage and lithium precipitation, thereby further improving the cycle performance and safety performance of the battery.

[0154] In some embodiments, the active cathode material layer further comprises a binder, wherein the binder comprises a dispersant, wherein the dispersant comprises hydrogenated nitrile rubber HNBR.

[0155] HNBR is obtained by hydrogenating nitrile rubber to saturate the double bonds. Its highly saturated main chain structure gives it excellent oil resistance, heat resistance, and aging resistance, among other properties. This makes it stable when used as a dispersant in various environments and systems, so it is less likely to degrade or decompose and can thus effectively exert its dispersing effect. The HNBR molecular chain contains both polar nitrile groups and nonpolar hydrocarbon chain segments.Polar nitrile groups can interact with some polar substances or the surfaces of the particles, for example, by adsorption onto the surface of dispersed particles through hydrogen bonding, electrostatic interactions, or the like. The nonpolar hydrocarbon chain segments exhibit good lipophilicity and can stretch and disperse well in nonpolar or weakly polar media, thus distributing the particles evenly throughout the medium. When HNBR is adsorbed onto the surface of the particles in the slurry, its long-chain molecules form a physical barrier around the particles, preventing them from approaching and aggregating, and thus keeping the particles in a relatively independent dispersed state within the system.Simultaneously, HNBR can reduce the surface tension between the dispersion medium and the dispersed particles, thereby facilitating wetting of the particles by the medium and promoting particle dispersion within the medium. It can also reduce the interfacial energy between the particles, thus decreasing interfacial energy-driven particle aggregation and improving the uniformity of the slurry. In an embodiment of the present application, the active cathode material layer comprises hydrogenated nitrile rubber HNBR as a dispersant, which contributes to improving the uniformity of the slurry. This further reduces misalignment, decreases the risk of current collector leakage and lithium precipitation, and improves the capacity of the battery cells, while simultaneously ensuring good cycle performance and safety.

[0156] In some embodiments, the mass content of the dispersing agent is provided to be 0.5% to 2% in relation to the total mass of the active cathode material layer.

[0157] In some embodiments, it is provided that, based on the total mass of the active cathode material layer, the mass content of the dispersant can be selected as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2% or a numerical range between any two values.

[0158] The mass fraction of the dispersant is within the aforementioned range, which helps to improve the uniformity of the slurry, further reduce alignment deviations, decrease the risk of current collector leakage and lithium precipitation, and improve the battery cell capacity, while also taking into account good cycle performance and safety performance.

[0159] In some embodiments, the active cathode material layer also comprises a conductive agent, wherein, with respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of an agglomerated region of the conductive agent is 0.5% to 2.5%.

[0160] In the present application, the area fraction of the agglomerated region of the conductive agent relative to the total area of ​​the active cathode material layer along the thickness direction of the battery cell can be tested using the following method. A procedure similar to the one described above is used to examine a cross-sectional area of ​​the active cathode material layer along the thickness direction of the electrode foil using a scanning electron microscope, and the area of ​​the agglomerated region of the conductive agent in the scanning electron microscope image is measured at a 3k-fold magnification.Since the conductive medium is generally a carbon-based material such as conductive carbon black or carbon nanotubes, aggregated conductive medium is visible under the high magnification of a scanning electron microscope, and the agglomerated region of the conductive medium often appears as a black agglomerate compared to other areas of the active cathode material layer. Using image analysis software, the agglomerated region of the conductive medium refers to the area in the scanning electron microscope image where the conductive medium is clearly aggregated and appears black. Specifically, the scanning electron microscope image is described as follows: 3.A 1000x magnification scan is imported into ImageJ. The black agglomerated area of ​​the conductive medium with a Feret value greater than or equal to 2 µm is selected, and the sum of the areas of the selected areas is counted and recorded as the area of ​​the agglomerated conductive medium. The area fraction of the conductive medium agglomeration area is the ratio of the area of ​​the agglomerated conductive medium to the total area of ​​the imported scanning electron microscope image. Three non-overlapping scanning electron microscope images are randomly selected, and the average of the area fraction of the conductive medium agglomeration area is calculated as the "area fraction of the conductive medium agglomeration area relative to the total area of ​​the active cathode material layer along the thickness direction of the battery cell."

[0161] In some embodiments, the active cathode material layer also comprises a conductive agent, wherein, relative to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the agglomerated region of the conductive agent can be selected as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or a numerical range between any two values.

[0162] With respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the agglomerated region of the conductive medium lies within the above range, which on the one hand shows that the cathode slurry has good uniformity, which helps to reduce alignment deviations and decrease the risk of current collector leakage and lithium precipitation, thereby improving the capacity of the battery cell while achieving good cycle performance and safety performance;On the other hand, it is shown that the conductive medium in the active cathode material layer is uniformly distributed and can easily form a uniform conductive network, which is particularly advantageous in reducing the problem of kinetic degradation caused by the growth of the ion transfer path in the thick coating film layer, reducing the local polarization and even lithium precipitation problem caused by the battery during the cycling process, and further improving the battery's cycle life.

[0163] In some embodiments, the active cathode material layer also comprises a conductive agent, wherein, with respect to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of an agglomerated region of the conductive agent is 1.5% to 2.5%.

[0164] In one embodiment of the present application, the area fraction of the agglomerated region of the conductive agent lies further within the above range, indicating that the conductive agent is more uniformly distributed in the active cathode material layer, and the content of the conductive agent is low, which helps to reduce the space occupied by the active cathode material due to an excessive conductive agent, thereby giving the battery good cycle performance, safety performance, dynamic properties and volume energy density.

[0165] In some embodiments, the conductive medium comprises a carbon nanotube, which includes one or more single-walled carbon nanotubes, thin-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0166] In the present application, the term "carbon nanotube" refers to a nanomaterial with several to dozen layers of coaxial hollow tubes formed by rolling up layers of graphene sheets connected by sp 2 Carbon nanotubes are formed by hybrid bonds between carbon atoms. Their diameter is typically in the range of a few to several tens of nanometers, and their length can range from micrometers to centimeters, indicating a high length-to-diameter ratio. Depending on the number of layers of graphene sheets, they can be classified as single-walled carbon nanotubes (SWCNTs), few-walled carbon nanotubes (FWCNTs), and multi-walled carbon nanotubes (MWCNTs). Carbon nanotubes exhibit excellent electrical conductivity and a high modulus of elasticity.

[0167] Since the carbon nanotube has a one-dimensional structure, it can form a network structure within the active cathode material layer. On the one hand, this network structure helps to distribute the particles in the slurry, improve the slurry uniformity, reduce alignment deviations, decrease the risk of current collector leakage and lithium precipitation, and further improve the battery's capacity while ensuring good cycle performance and safety. On the other hand, the excellent electrical conductivity of the carbon nanotube makes its network structure an efficient electron transfer channel, which helps to increase the electron transfer rate of thickly coated electrode foil in the thickness direction and improve the battery's dynamic properties.

[0168] In some embodiments, the conductive medium also includes conductive carbon black.

[0169] In some embodiments, the agglomerated area of ​​the conductive medium comprises the carbon nanotube and the conductive carbon black.

[0170] Researchers discovered that carbon nanotubes, due to their high surface energy, tend to agglomerate, leading to uneven distribution within their active cathode material layer and an inability to form an effective carbon nanotube network structure. The surface energies of conductive carbon black and carbon nanotubes are relatively close and can be adsorbed onto the surface of carbon nanotubes to form a physical barrier. This increases resistance to carbon nanotube agglomeration, reduces direct contact between carbon nanotubes, and thus prevents agglomeration and improves the uniformity of carbon nanotube distribution within the active cathode material layer.This contributes, on the one hand, to improving the electrical conductivity of the thickly coated active cathode material layer and increasing the battery's dynamic properties; on the other hand, it helps to utilize the three-dimensional network structure of the carbon nanotube to distribute the particles in the active cathode material layer, reduce misalignment, and further improve the battery's capacity, cycle life, and safety performance. Furthermore, the agglomeration of carbon nanotubes in the agglomerated region of the conductive medium also blocks local ion transfer pathways within this region, and the combination with conductive carbon black can improve the lithium-ion transfer capacity of this region, reduce local polarization, and further enhance the battery's cycle stability.

[0171] In some embodiments, it is provided that, with respect to the total mass of the active cathode material layer, the mass fraction C1 of the carbon nanotube meets the condition 0. <C1≤2,5% erfüllt, und der Massengehalt C2 des leitfähigen Rußes erfüllt die Bedingung 0<C2≤2,5%.

[0172] In some embodiments, it is provided that, relative to the total mass of the active cathode material layer, the mass fraction C1 of the carbon nanotube can be selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or a numerical range between any two values.

[0173] In some embodiments, it is provided that, based on the total mass of the active cathode material layer, the mass content C2 of the conductive carbon black can be selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or a numerical range between any two values.

[0174] The mass content of carbon nanotubes and conductive carbon black is within the aforementioned range, which effectively mitigates the agglomeration of carbon nanotubes and forms a good conductive network structure, thereby reducing alignment deviations, improving battery capacity, and considering cycle performance and safety performance.

[0175] In some embodiments, the one-sided areal density of the active cathode material layer is 0.25 g / 1540.25 mm². 2up to 0.45 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0176] In the present application, the single-sided coating areal density of the active cathode material layer has a meaning well known in this field and can be tested using methods known in this field. For example, a single-sided coated and cold-pressed cathode foil is taken (if it is a double-sided coated cathode foil, the active cathode material layer can be wiped off one side first), which is punched into small discs with an area of ​​S1 (during the punching process, the thinned area is avoided and the main body area is selected), the weight of which is weighed and recorded as M1. Then, the cathode film layer of the active cathode material layer of the weighed cathode foil is wiped off, and the weight of the current collector is weighed and recorded as M0. The single-sided areal density of the main body area = (M1 - M0) / S1. To ensure the accuracy of the test results, several sets (e.g.,10 sets) of the samples to be tested and the average value calculated as the test result. A higher one-sided coating area density of the active cathode material layer indicates an increased charge per unit area, which contributes to an increase in the volume energy density of the battery cell.

[0177] In some embodiments, the one-sided coating area density of the active cathode material layer is specified as 0.25 g / 1540 mm². 2 , 0.26 g / 1540 mm 2 , 0.27 g / 1540 mm 2 , 0.28 g / 1540 mm 2 , 0.29 g / 1540 mm 2 , 0.30 g / 1540 mm 2 , 0.31 g / 1540 mm 2 , 0.32 g / 1540 mm 2 , 0.33 g / 1540 mm 2 , 0.34 g / 1540 mm 2 , 0.35 g / 1540 mm 2 , 0.36 g / 1540 mm 2 , 0.37 g / 1540 mm 2 , 0.38 g / 1540 mm 2 , 0.39 g / 1540 mm 2 , 0.40 g / 1540 mm 2 , 0.41 g / 1540 mm 2, 0.42 g / 1540 mm 2 , 0.43 g / 1540 mm 2 , 0.44 g / 1540 mm 2 , 0.45 g / 1540 mm 2 or a numerical range between any two values ​​can be selected.

[0178] In some embodiments, the one-sided areal density of the active cathode material layer is 0.3 g / 1540.25 mm². 2 up to 0.45 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0179] In some embodiments, the one-sided areal density of the active cathode material layer is 0.35 g / 1540.25 mm². 2 up to 0.4 g / 1540.25 mm 2 is the value when the battery cell is in a completely discharged state.

[0180] If the one-sided coating area density of the active cathode material layer remains within the above range, this contributes to a further improvement in the battery's capacity. However, as the charge increases, the thickness of the active cathode material layer also increases accordingly. This triggers transition diffusion of the active cathode material layer during the coating-to-drying process, leading to misalignment. This, in turn, causes current collector leakage and lithium precipitation on the anode side, negatively impacting the energy density, cycle life, and safety performance of the battery cell.Therefore, in one embodiment of the present application, the one-sided thickness H of the main body region is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10% to 35%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L. A50 in a cumulative distribution curve of the particle sphericity area is 0.6 to 0.8; it is particularly suitable for battery cells with a one-sided areal density of the active cathode material layer within the above-mentioned range, which helps to achieve a balance between energy density, cycle performance and safety performance of the battery cells.

[0181] In some embodiments, the density of the cathode foil is specified as 2.3 g / cm³. 3 up to 2.6 g / cm³ 3 is the value when the battery cell is in a completely discharged state.

[0182] The density of the cathode foil can be tested in the present application using a method known in this field. For example, the battery is placed in an oven environment at 25 °C and left there for two hours.If the temperature remains at 25 °C, the battery is discharged with a constant current of 1 / 3 C to 2.5 V and then with a constant current of 0.1 C to 2.0 V. The battery is then disassembled to obtain the cathode foil. The remaining electrolyte solution is treated with dimethyl carbonate solvent. The electrode is dried and cut into small discs with an area of ​​S, each with a mass W1. The thickness T1 of the cathode foil is measured with a high-precision micrometer. The active cathode material layer is then wiped from the weighed electrode foil, the mass of which is weighed and recorded as W2. A high-precision micrometer is used to measure the thickness T2 of the current collector. The compaction density of the cathode foil is then PD = (W1 - W2) / [(T1 - T2) × S].

[0183] In some embodiments, the density of the cathode foil in the fully discharged state of the battery cell is provided to be 2.3 g / cm³. 3 , 2.31 g / cm³ 3 , 2.32 g / cm³ 3 , 2.33 g / cm³ 3 , 2.34 g / cm³ 3 , 2.35 g / cm³ 3 , 2.36 g / cm³ 3 , 2.37 g / cm³ 3 , 2.38 g / cm³ 3 , 2.39 g / cm³ 3 , 2.40 g / cm³ 3 , 2.41 g / cm³ 3 , 2.42 g / cm³ 3 , 2.43 g / cm³ 3 , 2.44 g / cm³ 3 , 2.45 g / cm³ 3 , 2.46 g / cm3, 2.47 g / cm 3 , 2.48 g / cm³ 3 , 2.49 g / cm³ 3 , 2.50 g / cm³ 3 , 2.52 g / cm³ 3 , 2.55 g / cm³ 3 , 2.6 g / cm³ 3 or a numerical range between any two values ​​can be selected.

[0184] A high compaction density contributes to increasing the volume energy density of the battery; a low compaction density reduces the porosity of the electrode foil and the liquid retention rate, which affects the transfer efficiency of lithium ions and thus the cycle performance and dynamic properties of the battery. In an embodiment of the present application, the compaction density of the cathode foil lies within the aforementioned range, which helps to achieve a balance between the energy density, cycle performance, and dynamic properties of the battery.

[0185] In some embodiments, the active cathode material layer also comprises an insulating layer 13, as shown in Fig. 1 shown, and the insulating layer 13 is arranged on a side of the thinned area 112 facing away from the main body area 111.

[0186] In one embodiment of the present application, the burrs on the edge of the electrode foil pierce the separator, causing the cathode and anode to overlap and resulting in self-discharge or short circuit of the battery. On the side of the thinned area facing away from the main body area, an insulating layer is applied, which helps to reduce the overlap of the cathode and anode caused by burrs on the edge of the electrode foil and thus improve the cycle life and safety performance of the battery cell.

[0187] In some embodiments, the insulating layer is provided for to comprise a metal oxide.

[0188] In some embodiments, the metal oxide is provided to comprise one or more of aluminium oxide, zirconium oxide, magnesium oxide and titanium oxide.

[0189] 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; wherein, in the thickness direction of the battery cell, the edge of the projection of the anode film layer lies on the outside of the insulating layer.

[0190] In the present application, the edge of the projection of the anode film layer in the thickness direction of the battery cell lies on the outside of the insulating layer, which means that the projection of the edge of the anode film layer in the thickness direction of the battery cell lies on the outside of the active cathode material layer.

[0191] The thickly coated electrode foil expands and deforms more during the cycling process, further reducing the size difference between the anode film layer and the active cathode material layer; in the thickness direction of the battery cell, the edge of the projection of the anode film layer falls onto the outside of the insulating layer, i.e., the size of the anode film layer exceeds that of the active cathode material layer, thus providing sufficient sites on the anode side for the embedding of lithium ions and reducing the risk of lithium precipitation on the anode side.

[0192] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the longitudinal direction of the battery cell is 4 mm to 16 mm.

[0193] In the present application, two of the longitudinal direction of the battery cell, the width direction of the battery cell and the thickness direction of the battery cell are perpendicular to each other, and the size of the battery cell in the longitudinal direction of the battery cell is greater than or equal to the size of the battery cell in the longitudinal direction of the battery cell.

[0194] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the longitudinal direction of the battery cell can be selected as 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, 11.5 mm, 12 mm, 12.5 mm, 13 mm, 13.5 mm, 14 mm, 14.5 mm, 15 mm, 15.5 mm, 16 mm, or a protection range between any two of the above values.

[0195] The size of the anode film layer and the active cathode material layer in the longitudinal direction is within the aforementioned range, which helps to provide sufficient sites for embedding lithium ions at the edge of the anode foil in the longitudinal direction, reducing the probability of lithium precipitation on the anode side and thus improving the cycle life of the battery.

[0196] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the width direction of the battery cell is 1 mm to 5 mm.

[0197] In some embodiments, the size difference between the anode film layer and the active cathode material layer in the width direction of the battery cell can be 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm or a numerical range between any two values.

[0198] The size of the anode film layer and the active cathode material layer in the lateral direction is within the aforementioned range, which helps to provide sufficient sites for embedding lithium ions at the edge of the anode foil in the lateral direction, reducing the probability of lithium precipitation on the anode side and thus improving the cycle life of the battery.

[0199] In some embodiments, the cathode tab is provided at at least one end of the cathode current collector main body, which extends along the longitudinal direction of the battery cell.

[0200] The cathode tab is provided at at least one end of the cathode current collector main body, extending along the longitudinal direction of the battery cell; that is, the tab is connected to the short side of the main body of the cathode current collector. This structure helps to reduce the volume of the insulating layer between the tab and the active cathode layer, decrease the volume occupied by inactive material on the cathode foil, and increase the charge of the active substance, thereby increasing the volume energy density of the battery cell. In some embodiments, the cathode tab is provided at at least one end of the cathode current collector main body, extending along the transverse direction of the battery cell.

[0201] The cathode tab is provided at at least one end of the cathode current collector main body, which extends along the width direction of the battery cell; that is, the long side of the tab is connected to the main body of the cathode current collector, thereby increasing the connection size between the tab and the main body of the current collector. This facilitates the processing of the tab and improves production efficiency, and also helps to increase the flow area at the connection between the current collector and the tab, reduce the internal resistance, and reduce the heat generation of the electrode foil.

[0202] It is available in some embodiments, such as in Fig. 2 shown provided that the separator 20 comprises a base film 201, a ceramic layer 202 arranged on at least one side of the base film 201, and an adhesive layer 203 arranged on a side of the ceramic layer 202 facing away from the base film 201, the adhesive layer 203 being a continuous layer with a porous structure and the adhesive layer 203 comprising a vinylidene fluoride polymer.

[0203] In some embodiments, the separator comprises a base film, a ceramic layer arranged on both sides of the base film, and an adhesive layer arranged on both sides facing away from the ceramic layer.

[0204] In some embodiments, the vinylidene fluoride polymer is provided to comprise one or more of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0205] In some embodiments, the vinylidene fluoride polymer comprises polyvinylidene fluoride (PVDF).

[0206] In the prior art, the adhesive layer of the separator typically consists of water-based PVDF, resulting in an island structure within the separator, as shown in Fig. Figure 3 shows that this is advantageous in order to provide gaps for the expansion of the battery cell and also simply facilitates manufacturing; however, the contact area between the adhesive layer of the separator and the electrode foil is small and the adhesive strength is weak.

[0207] The separator provided by an embodiment of the present application uses a continuous layer with a porous structure as an adhesive layer, as in Fig. 2 and Fig. Figure 4 shows that its porous structure provides space for the expansion of thick-coated battery cells, which helps to reduce the compression of the size difference between the anode film layer and the active cathode material layer by the thick-coated electrode foil. This ensures that there are sufficient sites on the anode side for lithium deposition, thus reducing the likelihood of lithium precipitation. Furthermore, in the prior art, the adhesive layer has a small contact area with the electrode foil and weak adhesive strength. When the active cathode material layer rebounds, this can lead to a relative displacement between the adhesive layer and the active cathode material layer, further reducing the size difference between the anode and the cathode.The probability of lithium precipitation increases and can even cause a short circuit between the cathode and the anode, impairing the battery's safety performance; furthermore, the extrusion between the separator and the electrode foil in the laminated battery cell is lower, and there is a higher probability of relative displacement between the separator and the electrode foil. Therefore, in embodiments of the present application, the bond between the separator and the electrode foil is stronger and more uniform, which helps to reduce the risk of relative displacement between the separator and the electrode foil, further reduce the probability of lithium precipitation, and improve the battery's safety performance.

[0208] It is understandable that the continuous adhesive layer may break and deform into a block structure due to contact or compression with the cathode or anode foil during the manufacturing or cycling process of the electrode foil. The continuous structure mentioned in the present application means that the adhesive layer of the separator is continuous at the microscopic level, for example, when viewed under a scanning electron microscope or an optical microscope. To reflect the true morphology of the separator, the area where the adhesive layer of the separator is not bonded to the cathode or anode foil in the battery is preferably sampled during the sampling process. For example, samples are taken at a position outside the separator position between the cathode and anode foils; alternatively, sampling can be performed on the separator near the surface of the electrode assembly.The sampling area of ​​the separator adheres less to the cathode foil or anode foil and can better reflect the actual condition of the separator.

[0209] In some embodiments, the material of the base film may comprise one or more of glass fibers, nonwoven fabrics, polyethylene (PE) and polypropylene (PP), but is not limited to these.

[0210] In some embodiments, the ceramic layer is provided to comprise one or more of aluminium oxide (Al2O3), zirconium oxide (ZrO2), titanium oxide (TiO2), silicon oxide (SiO2) and boron nitride (BN).

[0211] Ceramic particles are flame-retardant, highly hard, and resistant to heat deformation, resulting in excellent dimensional stability. Furthermore, the low thermal conductivity of ceramic materials can prevent specific thermal runaway points within the battery from developing into a general thermal runaway, thus improving the battery cell's safety performance.

[0212] In some embodiments, the thickness of the base film in the separator is provided to be 7 µm to 9 µm.

[0213] In some embodiments, it is provided that the thickness of the base film in the separator can be selected as 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm or a numerical range between any two values.

[0214] In some embodiments, the thickness of the ceramic layer on one side of the separator is 2 µm to 4 µm.

[0215] In some embodiments, it is provided that the one-sided thickness of the ceramic layer in the separator can be selected as 2 µm, 2.5 µm, 3 µm, 3.5 µm, 4 µm or a numerical range between any two values.

[0216] In some embodiments, the thickness of the adhesive layer on one side of the separator is 1 µm to 5 µm.

[0217] In some embodiments, it is provided that the one-sided thickness of the adhesive layer in the separator can be selected as 1 µm, 1.5 µm, 2 µm, 2.5 µm, 3 µm, 3.5 µm, 4 µm, 4.5 µm, 5 µm or a numerical range between any two values.

[0218] In the present application, "thickness" has a meaning known in this field and can be measured using methods and instruments known in this field. For example, a high-precision micrometer (e.g., Mitutoyo 293-100, with an accuracy of 0.1 µm) can be used.

[0219] The thickness of the adhesive layer is too small, the space in the gap in the separator is too small, and the adhesive strength between the separator and the electrode foil is insufficient. On the one hand, after the film layer expands, the size difference between the anode and the cathode decreases, increasing the risk of lithium precipitation; on the other hand, the probability of a short circuit between the cathode and anode due to overlap increases, negatively impacting the battery's safety performance. If the thickness of the adhesive layer is too great, it occupies a large amount of space in the battery, thereby impairing the battery's volumetric energy density. In one embodiment of the present application, the thickness of the adhesive layer is within the aforementioned range, which helps to simultaneously consider the battery's cycle life, safety performance, and volumetric energy density.

[0220] In some embodiments, the active cathode material layer is provided with a lower coating in a lower region facing the cathode current collector, and the lower coating comprises a conductive agent and a binder, the conductive agent comprising a carbon nanotube and conductive carbon black, the binder comprising polyvinylidene fluoride (PVDF).

[0221] In some embodiments, the thickness of the lower coating is provided for to be between 0.5 µm and 5 µm.

[0222] In some embodiments, it is provided that the thickness of the lower coating can be selected as 0.5 µm, 1 µm, 1.5 µm, 2 µm, 2.5 µm, 3 µm, 3.5 µm, 4 µm, 4.5 µm, 5 µm or a numerical range between any two values.

[0223] In comparison to direct contact between the cathode current collector and the active cathode material layer, the contact area between the lower coating and the active cathode material layer is increased, which helps to increase the area of ​​electron transfer between the current collector and the active cathode material layer, thereby reducing the internal resistance of the electrode foil and improving the dynamic properties of the battery.

[0224] In some embodiments, the cathode foil and the anode foil are stacked alternately along the thickness direction of the battery cell; the separator forms a continuous spiral structure or a continuous "Z"-shaped structure, wherein the separator is arranged to pass through between the cathode foil and the anode foil, which are adjacent to each other, in order to separate the cathode foil and the anode foil, which are adjacent to each other.

[0225] The separator in the battery cell is a continuous piece arranged in a spiral or Z-shape within the cathode foil and the anode foil. The separator has a certain position-limiting effect on the cathode foil and the anode foil, thus helping to reduce the risk of relative displacement between the cathode foil and the anode foil and to improve the safety performance and cycle performance of the battery.

[0226] In some embodiments, the battery cell also includes a shell in which the laminated battery cell is received, and the shell material is a soft packaging material, and the soft packaging material comprises an aluminum-plastic composite film.

[0227] In some embodiments, the shell material comprises a composite film of aluminum and one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), or polyethylene (PE).

[0228] The soft packaging material exhibits high elongation, allowing its shell to be thinner and softer, which contributes to better space utilization within the battery cell and thus increases the battery cell's energy density. Furthermore, the high barrier properties of aluminum effectively reduce the penetration of water and oxygen into the battery's interior, decrease electrolyte degradation and the oxidation level of the electrode material, and thus extend the battery's lifespan.

[0229] In some embodiments, the battery cell comprises a shell in which the laminated battery cell is received, wherein the size of the shell in the longitudinal direction is L1, the size of the shell in the width direction is W1, and the size of the shell in the thickness direction is H1, where 450 mm ≤ L1 ≤ 1300 mm, 100 mm ≤ W1 ≤ 150 mm; where 14 mm ≤ H1 ≤ 22 mm.

[0230] In some embodiments, L1 is provided to be 450 mm, 480 mm, 490 mm, 500 mm, 510 mm, 520 mm, 530 mm, 540 mm, 550 mm, 560 mm, 570 mm, 580 mm, 590 mm, 600 mm, 610 mm, 620 mm, 630 mm, 640 mm, 650 mm, 660 mm, 670 mm, 680 mm, 690 mm, 700 mm, 710 mm, 720 mm, 750 mm, 800 mm, 850 mm, 900 mm, 950 mm, 1000 mm, 1050 mm, 1100 mm, 1150 mm, 1200 mm, 1250 mm, 1300 mm or a numerical range between any two values ​​can be selected.

[0231] In some embodiments, W1 can be selected as 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, or any numerical range between any two values. In some embodiments, H1 can be selected as 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, or any numerical range between any two values.

[0232] In some embodiments, the size of the shell in the longitudinal direction is L1, where 450 mm ≤ L1 ≤ 650 mm.

[0233] If the shell size in the longitudinal direction L1 meets the condition L1 ≤ 450 mm ≤ L1 ≤ 650 mm, the battery cell length is shorter, which helps to shorten the current diffusion path and reduce the internal resistance of the electrode foil, thereby reducing the heat generation of the battery and improving its dynamic properties; furthermore, the shorter shell length helps to shorten the diffusion path of the electrolyte solution during the wetting process, improve the wetting rate and uniformity of the electrolyte solution, further promote the uniformity of the deintercalation of lithium ions during the cycling process, and improve the cycle stability of the battery cell.

[0234] In some embodiments, the size of the shell in the longitudinal direction is L1, where 900mm ≤ L1 ≤ 1300mm.

[0235] If the shell dimensions in the longitudinal direction L1 ≤ 900 mm ≤ L1 ≤ 1300 mm, the battery cell is longer, which helps to reduce the volume fraction of the shell in the battery cell and increase the charge fraction of the active material. At the same time, a longer battery cell can reduce the number of batteries required in the battery module, simplify the structural design of the battery module, decrease the number and complexity of structural components in the module, and thus improve the space utilization of the battery pack and further contribute to improving the volume energy density of the battery cell.

[0236] In some embodiments, the lithium-containing transition metal phosphate particles are provided to comprise components that are represented by the following general formula: Li m Fe x P y O j Q q Formula 1 where Q comprises one or more of Al, Na, K, Mg, Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb, V, Ti, B, S, Si, N, F, Cl, Br, where 0.8 ≤ m ≤ 1.15, 0.9 ≤ x ≤ 1, 0.95 ≤ y ≤ 1, 3.5 ≤ j ≤ 4, 0 < q ≤ 0.1.

[0237] In some embodiments, m can be selected as 0.8, 0.85, 0.9, 0.95, 0.98, 1.00, 1.03, 1.05, 1.08, 1.10, 1.13, 1.15 or a numerical range between any two values; x can be selected as 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0 or a numerical range between any two values; y can be selected as 0.95, 0.96, 0.97, 0.98, 0.99, 1.00 or a numerical range between any two values; j can be selected as 3.5, 3.6, 3.7, 3.8, 3.9, 4 or a numeric range between any two values; q can be selected as 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or a numeric range between any two values.

[0238] In some embodiments, the lithium-containing transition metal phosphate particles in the active cathode material layer comprise one or more of lithium iron phosphate, lithium manganese phosphate, lithium fluorovanadium phosphate, lithium manganese iron phosphate and modified materials thereof.

[0239] In some embodiments, the lithium-containing transition metal phosphate particles in the active cathode material layer comprise one or more lithium iron phosphate and its doped modified material and encasing modified material.

[0240] The second aspect of the present application provides a battery device comprising the battery cell provided in the first aspect of the present application.

[0241] In some embodiments, the battery device is provided to further include a housing, as in Fig. As shown in Figure 5, several battery cells 30 are stacked in a row along the thickness direction and connected in the housing; a reinforcing partition plate 40 is provided between the large surfaces of the shells of two adjacent battery cells 30, wherein the reinforcing partition plate 40 is connected to the housing, the stiffness of the reinforcing partition plate 40 being greater than the stiffness of the shells of the battery cells 30.

[0242] By providing and connecting the reinforcing partition plate to the housing, the reinforcing partition plate can be fixed so that the reinforcing partition plate can effectively support the battery cell, improve the stiffness of the battery cell and thus improve the stiffness of the entire battery device.

[0243] It is available in some embodiments, such as in Fig. Figure 5 shows that two reinforcing separating plates 40, arranged side by side along the thickness direction and distributed on both sides of at least one battery cell 30 in the thickness direction, are connected to each other by a connecting plate 50, which is located in the outer circumferential area of ​​the battery cell.

[0244] The connecting plate can be provided to improve the reliability of the support offered by the reinforcing separator plate of the battery cell.

[0245] In some embodiments, the connecting plate is arranged between the two reinforcing partition plates and integrally joined to them to form a U-shaped shell. The process of joining the connecting plate to the reinforcing partition plate can be omitted, and the reliability of the connection between the connecting plate and the reinforcing partition plate can be further improved.

[0246] The battery device disclosed in the embodiments of the present application can be used in electrical devices that utilize the battery device as a power source, or in various energy storage systems that use the battery device as an energy storage element. The battery device can be used not only in vehicles, but also in mobile phones, tablets, laptops, electric toys, power tools, battery-powered carts, electric vehicles, ships, spacecraft, and the like, but is not limited to these. Electric toys include, for example, stationary or mobile electric toys such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and so on, and spacecraft include, for example, airplanes, rockets, spacecraft, and space vehicles, and so on.

[0247] The third aspect of the present application also provides a power-consuming device that uses the battery device as a power source, wherein the power-consuming device comprises the at least one battery cell, battery module, or battery pack provided in the present application. The battery cell, battery module, or battery pack can be used as a power source for the power-consuming device or as an energy storage unit for the power-consuming device. Depending on the usage requirements, a battery cell, battery module, or battery pack can be selected as the power-consuming device. Fig.Figure 6 shows, as an example, a power-consuming device. The power-consuming device disclosed by the embodiments of the present application can be a fuel-powered vehicle, a gas-powered vehicle, or a vehicle with a new energy source, and the vehicle with a new energy source can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, or the like. A battery device is provided inside the vehicle, and the battery device can be located at the bottom, at the front, or at the rear of the vehicle. The battery device can be used to power a vehicle; for example, the battery device can serve as an operating current source for the vehicle.The vehicle may further include a control unit and a motor. The control unit is used to manage the battery device and supply power to the motor, for example, to meet the vehicle's power requirements for starting, navigating, and driving. In some embodiments of the present application, the battery device may serve not only as the vehicle's operating power source but also as its propulsion power source, wholly or partially replacing fuel or natural gas to provide motive power for the vehicle.

[0248] A fourth aspect of the present application relates to an energy storage device which uses a battery device as a power source; the energy storage device may be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power plant, an energy storage battery pack or a portable energy storage system. Examples of implementation

[0249] The following are exemplary embodiments of the present application. These embodiments are examples and serve only to illustrate the present application; they should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the exemplary embodiments, the techniques or conditions described in the technical literature or the product instructions must be followed. The reagents or instruments used without manufacturer information are exclusively commercially available products.

[0250] The following are exemplary embodiments of the present application. These embodiments are examples and serve only to illustrate the present application; they should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the exemplary embodiments, the techniques or conditions described in the technical literature or the product instructions must be followed. The reagents or instruments used without manufacturer information are exclusively commercially available products. Exemplary embodiment 1(1) Production of active cathode material

[0251] Lithium carbonate, iron phosphate, titanium dioxide, vanadium pentoxide, sucrose, glucose, and polyethylene glycol are added to deionized water and mixed in a premix tank, the ratio of lithium carbonate to iron phosphate being such that the molar ratio of lithium to iron is 1.02:1.0. Based on the total mass of the mixed raw material, the mass content of sucrose is 2%, the mass content of glucose is 4%, and the mass content of polyethylene glycol is 5%. After uniform mixing, a mixed raw material with a solids content of 45% is obtained. The mixed raw material is divided into two parts in a 1:1 ratio and then each part is milled and demagnetized in a ball mill to obtain a first milled material and a second milled material. The first milled material is ground in a sand mill with a milling time of 12 hours and a frequency of 24 Hz. During the milling process, the slurry temperature is controlled to less than 40°C to obtain a first milling slurry with a particle size Dv50 of the solid particles in the first milling slurry of 0.5 µm. The second milled material is ground in a sand mill with a milling time of 8 hours and a frequency of 22 Hz. During the milling process, the slurry temperature is controlled to less than 40°C to obtain a second milling slurry with a particle size Dv50 of the solid particles in the second milling slurry of 1.8 µm.The first milling slurry and the second milling slurry are mixed in a mass ratio of 85:15 and spray-dried to obtain a mixed precursor powder; The mixed slurry is spray-dried to obtain a precursor powder, which is then sintered to produce a lithium iron phosphate cathode material. The sintering process comprises the following: the precursor powder is sintered in a nitrogen atmosphere in two stages with increasing temperatures to obtain the active cathode material: heating from 25°C to 500°C at a temperature increase rate of 3°C / min (first heating stage) and held for 3 hours; heating from 500°C to 780°C at a temperature increase rate of 5°C / min (second heating stage) and held for 10 hours; the aeration volume in the heating stage is 1.3:1 larger than in the constant temperature stage, with a total aeration volume of 1500 cm³. 3 / h, and after the end the temperature is lowered to below 100 °C; The sintered product is pulverized using an airflow process, and the Dv90 particle size is adjusted to 5 to 10 µm, resulting in an active cathode material made of lithium iron phosphate with a carbon material applied to the surface. Based on the total mass of the active cathode material, the mass fraction of the titanium element is 1000 ppm and the mass fraction of the volatile element is 900 ppm. The values ​​Dv10, Dv50 and Dv90 mentioned above refer to the particle size values ​​corresponding to achieving a percentage of the cumulative particle volume distribution of 10%, 50% and 90% respectively, as tested using the Malvern laser scattering method. (2) Production of the cathode foil

[0252] The above active cathode material (95% by mass), the conductive agent (1.5% by mass), the polyvinylidene fluoride (PVDF) binder (2.5% by mass), and the HNBR dispersant (1% by mass) are mixed in an N-methylpyrrolidone solvent. The mixture is thoroughly mixed, stirred, and dispersed in a stirred tank to produce a cathode slurry. After stirring, the cathode slurry is transferred to the coating process. The mass fractions of the active cathode material, conductive agent, binder, and dispersant are calculated based on the total mass of solids in the cathode slurry.The conductive agent comprises conductive carbon black with a mass fraction of 1% and carbon nanotubes with a mass fraction of 0.5%, the specific surface area of ​​the conductive carbon black is 85 m2 / g, the oil absorption value is 200 ml / 100 g, the average length of the carbon nanotube is 25 µm, the specific surface area is 300 m2 / g, and the mass content of metallic impurities in the carbon nanotube is less than 1 wt.%;

[0253] Aluminum foil is chosen as the cathode current collector; the thickness of the aluminum foil is 8 µm. The cathode slurry is applied to the aluminum foil by extrusion coating, dried, and then roller-pressed to produce a cathode foil with a one-sided thickness of the cathode film layer of 105.76 µm and a compaction density of 2.34 g / cm³. 3to obtain. The rolling process comprises a cold rolling process and a hot rolling process, and the cold rolling pressure at room temperature is 45 tons, the hot rolling pressure at 70 °C is 75 tons, the range value of the thickness of the cathode film layer after the hot rolling process is 0.5 µm.

[0254] An insulating layer was arranged between the active cathode material layer and the cathode tab, and the alignment deviation E of the cathode film layer on both sides in the thickness direction of the battery cell is 0.3 mm. (3) Production of the anode foil

[0255] Large-grained artificial graphite with a relatively concentrated particle size distribution is selected; the particle size Dv10 of the artificial graphite powder is specifically 9 µm, the particle size Dv50 is 20 µm, the particle size Dv90 is 40 µm, and the graphitization degree of the artificial graphite is 93%; the aforementioned values ​​Dv10, Dv50, and Dv90 refer to the particle size values ​​corresponding to achieving a percentage of the cumulative particle volume distribution of 10%, 50%, and 90%, respectively, as tested using the Malvern laser scattering method;

[0256] Artificial graphite, conductive agent made from conductive carbon black, binder made from styrene-butadiene rubber (SBR) and thickener made from sodium carboxymethylcellulose (CMC) are mixed uniformly in a weight ratio of 95:1.0:2.0:2.0 and added to deionized water, and after stirring and dispersing, the anode slurry is obtained and the base material made of copper foil is coated with the anode slurry, and after drying, cold pressing, cutting and foil forming, the anode foil is obtained.

[0257] The length of the active cathode material layer is 544.5 mm and the width is 118.2 mm, and the length of the anode film layer is 550 mm and 119.5 mm. (4) Separator

[0258] Polyvinylidene fluoride (PVDF) is dissolved in N-methylpyrrolidone (NMP), stirred thoroughly, and polyethylene glycol (PEG) is added as a pore-forming agent. The mixture is stirred and mixed thoroughly to obtain an adhesive layer solution. This adhesive layer solution is applied to the base film, which has ceramic layers on both sides. It is pre-evaporated at 80 °C, dried at 110 °C, and then immersed in deionized water to dissolve the PEG, resulting in a separator with adhesive layers featuring porous structures on both sides. The base film is 8 µm thick, the ceramic layer on one side is 3 µm thick, and the adhesive layer on one side is 1 µm thick. (5) Electrolyte solution

[0259] In a glovebox with an argon atmosphere (H₂O < 0.1 ppm, O₂ < 0.1 ppm), the organic solvents dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) are mixed uniformly in a mass ratio of 30:50:20. Lithium hexafluorophosphate is then added and dissolved in the organic solvents to adjust the concentration of the electrolyte solution to 1.05 mol / L, and the mixture is stirred uniformly to obtain the electrolyte solution from embodiment 1. (6) Battery manufacturing:

[0260] The cathode foils and anode foils are stripped and punched into specific shapes, and the punched cathode foils are sorted by weight using a weighing sorting machine. The cathode foils and anode foils are sent to the compounding station, and the cathode foils and The anode foils are alternately thermally bonded on the single-sided surface of the separator to form a three-in-one composite tape. This composite tape is continuously wound to a preset number of layers. The winding process is stopped, and the composite tape is cut. The separator forms a spiral structure between the cathode and anode foils, which are positioned side by side, to create a laminated battery cell. The laminated battery cell is then bonded to tightly encase it. The laminated battery cell is then bonded with adhesive into an outer packaging made of a flexible material such as aluminum-plastic film. This aluminum-plastic film consists of an inner layer of polypropylene, an intermediate layer of aluminum foil, and an outer layer of nylon. The aluminum-plastic film outer packaging is die-cut on both sides using a die-cutting and forming machine. The material is cut to the desired shape and size. The aluminum-plastic film is then heat-sealed to ensure a tensile strength of ≥25 N / 8 mm. The battery is vacuum-baked, allowed to rest, filled with electrolyte solution, and packaged. The softpack battery is then hot-pressed and cold-pressed. at a temperature of 45 °C, a duration of 2 minutes and a pressure of 90 kg / cm² 2 during hot pressing at a temperature of 25 °C, a duration of 2 minutes and a pressure of 90 kg / cm² 2 During cold pressing, the battery cell is obtained after the processes of forming, vacuum extraction, and trimming. The battery cell has dimensions of 600 mm in length, 125 mm in width, and a thickness (H1) of 20 mm. Example 2:

[0261] The manufacturing process of embodiment 2 is basically the same as that of embodiment 1, with the exception that the manufacturing process of the active cathode material, the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ; the specific differences are as follows: The differences in the manufacturing process of the active cathode material are as follows: (1) The first grinding material and the second grinding material are mixed in a mass ratio of 60:40 to obtain a mixed intermediate product; the mixed intermediate product is spray-dried; (2) The precursor powder material is sintered to obtain the lithium iron phosphate cathode material; the sintering process includes the following: First sintering: the precursor powder is sintered in a nitrogen atmosphere with a temperature increase rate of 2°C / min from 25°C to 765°C and held at this temperature for 8 hours; after cooling, the first sintered product is obtained; Second sintering: the dried mixed intermediate product is sintered in a nitrogen atmosphere with a temperature increase rate of 2°C / min from 25°C to 800°C and held at this temperature for 10 hours; after cooling, the second sintered product is obtained.

[0262] The differences in the manufacturing process of the cathode foil are: by adjusting pressure, calendering speed, rolling time, rolling temperature and controlling the coating thickness of the slurry in the rolling process, a cathode foil with a cathode film layer with a one-sided thickness of 105.89 µm and a compaction density of 2.34 g / cm³ is produced. 3 receive.

[0263] The size of the film layer in the electrode foil is: The length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 550.8 mm and 120.3 mm. Example 3:

[0264] The manufacturing process of embodiment 3 is basically the same as that of embodiment 1, with the exception that the manufacturing process of the active cathode material, the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ; the specific differences are as follows: The differences in the manufacturing process of the active cathode material are as follows: (1) The first grinding material and the second grinding material are mixed in a mass ratio of 30:70 to obtain a mixed intermediate product; the mixed intermediate product is spray-dried; (2) The precursor powder material is sintered to obtain the lithium iron phosphate cathode material; the sintering process includes the following: First sintering: the precursor powder is sintered in a nitrogen atmosphere with a temperature increase rate of 2°C / min from 25°C to 765°C and held at this temperature for 8 hours; after cooling, the first sintered product is obtained; Second sintering: the dried mixed intermediate product is sintered in a nitrogen atmosphere with a temperature increase rate of 5°C / min from 25°C to 850°C and held at this temperature for 12 hours; after cooling, the second sintered product is obtained.

[0265] The differences in the manufacturing process of the cathode foil are: By adjusting pressure, calendering speed, rolling time, rolling temperature and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer with a one-sided thickness of 106.42 µm and a compaction density of 2.36g / cm³ is produced. 3 receive.

[0266] The size of the film layer in the electrode foil is: The length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 550.8 mm and 120.3 mm. Example 4

[0267] The manufacturing process of embodiment 4 is basically the same as that of embodiment 1, except that the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ. The specific differences are as follows: the meal is changed to obtain a second meal slurry, wherein the particle size Dv50 of the solid particles in the second meal slurry is 2.5 µm; the differences in the manufacturing process of the cathode foil are: The manufacturing process for the cathode foil is adapted; specifically, by adjusting pressure, calendering speed, rolling time, rolling temperature, and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer having a one-sided thickness of 126.51 µm and a compaction density of 2.35 g / cm³ is produced. 3 receive.

[0268] The size of the film layer in the electrode foil is: The length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 546.8 mm and 119.9 mm. Example 5

[0269] The manufacturing process of embodiment 5 is basically the same as that of embodiment 4, with the exception that the manufacturing process of the active cathode material differs; the specific differences are as follows: The manufacturing process for the cathode foil is adapted; specifically, by adjusting pressure, calendering speed, rolling time, rolling temperature, and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer having a one-sided thickness of 90.14 µm and a compaction density of 2.35 g / cm³ is produced. 3 receive. Comparative example 1

[0270] The manufacturing process of the comparative example is basically the same as that of embodiment 3, with the exception that the manufacturing process of the active cathode material, the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ; the specific differences are as follows: The differences in the manufacturing process of the active cathode material are as follows: The first and second milled materials are mixed in a mass ratio of 10:90 to obtain a mixed intermediate product; the mixed intermediate product is spray-dried;

[0271] The differences in the manufacturing process of the cathode foil are: The manufacturing process for the cathode foil is adapted; specifically, by adjusting pressure, calendering speed, rolling time, rolling temperature, and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer having a one-sided thickness of 105.62 µm and a compaction density of 2.35 g / cm³ is produced. 3 receive.

[0272] The size of the film layer in the electrode foil is: The length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 548.8 mm and 120.3 mm. Comparative example 2

[0273] The manufacturing process of the comparative example is basically the same as that of embodiment 2, with the exception that the manufacturing process of the active cathode material, the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ; the specific differences are as follows: The first and second grinding materials are mixed in a mass ratio of 90:10 to obtain a mixed intermediate product; the mixed intermediate product is spray-dried;

[0274] The differences in the manufacturing process of the cathode foil are: The manufacturing process for the cathode foil is adapted; specifically, by adjusting pressure, calendering speed, rolling time, rolling temperature, and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer having a one-sided thickness of 91.23 µm and a compaction density of 2.35 g / cm³ is produced. 3 receive.

[0275] The size of the film layer in the electrode foil is: the length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 550.8 mm and 120.3 mm. Comparative example 3

[0276] The manufacturing process of comparative example 3 is basically the same as that of embodiment 1, with the exception that the manufacturing process of the active cathode material, the manufacturing process of the cathode foil and the size of the film layer in the electrode foil differ; the specific differences are as follows: The differences in the manufacturing process of the active cathode material are as follows: The second milling material is ground in a sand mill for 4 hours at a frequency of 25 Hz. During the milling process, the slurry temperature is controlled to below 40 °C to obtain a second milling slurry, where the particle size Dv50 of the solid particles in the second milling slurry is 1.8 µm; the first milling slurry and the second milling slurry are mixed in a mass ratio of 60:40 and spray-dried to obtain a mixed precursor powder;

[0277] The differences in the manufacturing process of the cathode foil are: The manufacturing process for the cathode foil is adapted; specifically, by adjusting pressure, calendering speed, rolling time, rolling temperature, and controlling the coating thickness of the slurry during the rolling process, a cathode foil with a cathode film layer having a one-sided thickness of 106.21 µm and a compaction density of 2.35 g / cm³ is produced. 3 receive.

[0278] The size of the film layer in the electrode foil is: The length of the active cathode material layer is 544.3 mm and the width is 118.7 mm, and the length of the anode film layer is 550.8 mm and 120.3 mm. Test procedure 1. Battery cell capacity

[0279] Charging at 25 °C with a charging rate of 0.5 C of the nominal capacity of the battery cell to 3.65 V, then charging with a constant voltage of 3.65 V to 0.05 C and leaving for 10 minutes, subsequently discharging with a discharge rate of 1 C to 2.5 V and leaving for 10 minutes, whereby the capacity C during the discharge process is calculated using the formula C=I×t in the unit Ah. 2. Test for lithium precipitation during trickle charging of a battery cell at 60 °C

[0280] Place the battery cell in a 60°C thermostated enclosure for 24 hours to ensure the battery temperature reaches 60°C; after charging the battery cell with a constant current of 0.1C to 3.8 V, charge it at a constant voltage of 3.8 V, start the timer, and maintain the voltage at this level for 336 hours; after charging, disassemble the battery cell and remove the anode foil, which should appear golden yellow. If grayish-white, silver, or brown spots are present, this indicates a lithium deposition area, and the area of ​​lithium deposition is measured. If the maximum diameter of the spots in the lithium precipitation area is less than or equal to 5 mm, or if the proportion of the total area of ​​the lithium precipitation area is less than or equal to 2% of the total area of ​​the anode film layer, slight lithium precipitation is assumed; if the maximum diameter of the spots in the lithium precipitation area is greater than 5 mm and the proportion of the total area of ​​the lithium precipitation area is greater than 2% of the total area of ​​the anode film layer, heavy lithium precipitation is assumed. Test results

[0281] The test results for the above embodiments and comparison examples are listed in Table 1. Table 1

[0282] From the comparison between the exemplary embodiments and the comparative examples, it can be seen that the battery cell comprises a laminated battery cell, wherein the laminated battery cell comprises a cathode foil, a separator, and an anode foil stacked one behind the other; wherein the cathode foil comprises a cathode current collector main body, a cathode tab, and an active cathode material layer, wherein the active cathode material layer is arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, wherein the cathode tab is arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprises a main body region and a thinned region arranged on one side of the main body region facing the cathode tab, wherein the thickness of the thinned region is less than that of the main body region;wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles that are provided with a carbon material on at least part of their surface; wherein the one-sided thickness H of the main body region is 70 µm to 120 µm when the battery cell is in a fully discharged state; wherein, based on the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that satisfies a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the L is; A50 in the cumulative distribution curve of the particle sphericity area 0.6 to 0.8, thereby improving the problems of current collector leakage and lithium precipitation in thick-coated battery cells and taking into account cycle life and safety performance while maintaining high capacity. By comparing embodiment 3 with embodiments 1 and 2, it can be seen that, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of particles with a particle size R2 that meets the condition R2 ≥ 1000 nm is 12% to 30%, which helps to further reduce the alignment deviation, improve the aluminum leakage of the electrode foil and increase the cycle performance of the battery cell.

[0283] A comparison between embodiment 3 and comparative example 1 shows that while embodiment 3 also exhibits an aluminum leak, the degree of aluminum leakage in embodiment 3 is lower compared to comparative example 1, resulting in only a small amount of aluminum leakage. Furthermore, the comparison between embodiment 3 and comparative example 1 shows that the size difference between the anode film layer and the active cathode material layer is small in the longitudinal direction, which increases the risk of lithium precipitation.On the contrary, if a larger area is reserved, lithium precipitation can be slowed down to a certain extent. It is speculated that this is due to the increased expansion and deformation of the electrode foil during the cycling process and the low bond strength between the laminated layers, which easily leads to a positional shift between the cathode foil and the anode foil. This results in insufficient space on the anode side to accommodate the ions released from the cathode side, leading to lithium precipitation. A comparison between embodiment 3 and comparative example 3 shows that in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the L. A50 in the cumulative distribution curve of the particle sphericity area lies in the range of 0.6 to 0.8, which helps to reduce the degree of aluminium leakage, thereby improving lithium precipitation from the electrode foil and improving the cycle performance of the battery cell.

[0284] A comparison between embodiments 1 to 3 and embodiments 5 and 4 shows that the thickness of the main body area on one side increases, i.e., the areal density of the active cathode material layer on one side increases, which contributes to improving the battery cell's capacity. However, embodiments 4 and 5 show that with a thicker coating and a small size difference between the anode film layer and the cathode film layer in the longitudinal direction, lithium precipitation occurs, even if no aluminum leakage occurs in the cathode foil produced by the coating.Therefore, the one-sided thickness of the main body area is in the range of 100 µm to 120 µm, which helps to take into account the capacity of the battery while simultaneously improving the lithium precipitation of the electrode foil and taking into account the cycle performance and safety performance of the battery cell.

[0285] It should be noted that the present application 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 application are all included within the technical scope of the present application. Furthermore, other embodiments in which various modifications conceivable by 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 application without departing from the core of the present application. 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 2025 / 094369

[0001]

Claims

[1] Battery cell, characterized by , that the battery cell comprises a laminated battery cell, wherein the laminated battery cell comprises a cathode foil, a separator and an anode foil stacked one behind the other; wherein the cathode foil comprises a cathode current collector main body, a cathode tab and an active cathode material layer, wherein the active cathode material layer is arranged on both sides of the cathode current collector main body along the thickness direction of the battery cell, wherein the cathode tab is arranged on at least one side of the cathode current collector main body; wherein the active cathode material layer comprises a main body region and a thinned region arranged on one side of the main body region facing the cathode tab, wherein the thickness of the thinned region is less than that of the main body region; wherein the active cathode material layer comprises an active cathode material, wherein the active cathode material comprises lithium-containing transition metal phosphate particles which are provided with a carbon material on at least part of their surface; wherein the one-sided thickness H of the main body area is 70 µm to 120 µm when the battery cell is in a fully discharged state; where, with reference to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R1 that meets a condition 50 nm ≤ R1 ≤ 400 nm is 10.0% to 35.0%; wherein in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.6 to 0.

8. [2] Battery cell according to claim 1, characterized by , that the one-sided thickness H of the main body area is 90 µm to 120 µm, optionally 100 µm to 120 µm when the battery cell is in a fully discharged state. [3] Battery cell according to claim 1 or 2, characterized by , that in a cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell L A 50 in a cumulative distribution curve of the sphericity area of ​​the particles is 0.65 to 0.75, optionally 0.67 to 0.

72. [4] Battery cell according to any one of claims 1 to 3, characterized by , that the projections of the edges of the two thinned areas on both sides of the cathode current collector main body, facing away from the main body area, onto the cathode current collector main body in the thickness direction of the battery cell are A and B respectively, wherein the minimum distance E between A and B is 0.1 mm to 0.6 mm, optionally 0.1 mm to 0.4 mm. [5] Battery cell according to any one of claims 1 to 4, characterized by , that, with respect to the total area of ​​the particles in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of the particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is 12% to 30%. [6] Battery cell according to any one of claims 1 to 5, characterized by , that in the cross-sectional area of ​​the active cathode material layer along the thickness direction of the battery cell the uniformity of the distribution of particles with a particle size R2 that meets a condition R2 ≥ 1000 nm is less than or equal to 5.0%, optionally 0.2% to 2.5%, and further optionally 0.2% to 2%. [7] Battery cell according to any one of claims 1 to 6, characterized by, that the active cathode material layer further comprises a binder, wherein the binder comprises a dispersant, wherein the dispersant comprises hydrogenated nitrile rubber HNBR; and / or wherein the mass content of the dispersant is 0.5% to 2% based on the total mass of the active cathode material layer. [8] Battery cell according to any one of claims 1 to 7, characterized by , that the active cathode material layer also comprises a conductive medium, wherein, in relation to the total area of ​​the active cathode material layer along the thickness direction of the battery cell, the area fraction of an agglomerated region of the conductive medium is 0.5% to 2.5%, optionally 1.5% to 2.5%. [9] Battery cell according to claim 8, characterized by, that the conductive medium comprises carbon nanotubes, comprising one or more single-walled carbon nanotubes, thin-walled carbon nanotubes and multi-walled carbon nanotubes, optionally the conductive medium also comprising conductive carbon black. [10] Battery cell according to claim 8 or 9, characterized by , that the agglomerated area of ​​the conductive medium comprises the carbon nanotube and the conductive soot. [11] Battery cell according to claim 9 or 10, characterized by , that, with respect to the total mass of the active cathode material layer, the mass content C1 of the carbon nanotube meets the condition 0 <C1≤2,5% erfüllt, wobei der Massengehalt C2 des leitfähigen Rußes die Bedingung 0<C2≤2,5% erfüllt. [12] Battery cell according to any one of claims 1 to 11, characterized by , that the one-sided areal density of the active cathode material layer is 0.25 g / 1540.25 mm 2 up to 0.45 g / 1540.25 mm 2is, optionally 0.3 g / 1540.25 mm 2 up to 0.45 g / 1540.25 mm 2 , further optional 0.35 g / 1540.25 mm 2 up to 0.4 g / 1540.25 mm 2 , when the battery cell is in a completely discharged state. [13] Battery cell according to any one of claims 1 to 12, characterized by , that the compaction density of the cathode foil is 2.3 g / cm³ 3 up to 2.6 g / cm³ 3 is the value when the battery cell is in a completely discharged state. [14] Battery cell according to any one of claims 1 to 13, characterized by , that the cathode foil further comprises an insulating layer, wherein the insulating layer is arranged on a side of the thinned region facing away from the main body region. [15] Battery cell according to claim 14, characterized by that the insulating layer comprises a metal oxide, optionally comprising one or more of aluminium oxide, zirconium oxide, magnesium oxide and titanium oxide. [16] Battery cell according to claim 14 or 15, characterized by , that 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, in the thickness direction of the battery cell, the edge of the projection of the anode film layer lies on the outside of the insulating layer. [17] Battery cell according to claim 16, characterized by , that the size difference between the anode film layer and the active cathode material layer in the longitudinal direction of the battery cell is 4 mm to 16 mm. [18] Battery cell according to claim 16, characterized by , that the size difference between the anode film layer and the active cathode material layer in the width direction of the battery cell is 1 mm to 5 mm. [19] Battery cell according to any one of claims 1 to 18, characterized by, that the cathode tab is provided at at least one end of the cathode current collector main body, which extends along the longitudinal direction of the battery cell. [20] Battery cell according to any one of claims 1 to 18, characterized by that the cathode tab is provided at at least one end of the cathode current collector main body, which extends along the width direction of the battery cell. [21] Battery cell according to any one of claims 1 to 20, characterized by , that the separator comprises a base film, a ceramic layer arranged on both sides of the base film and an adhesive layer arranged on at least one side of the ceramic layer facing away from the base film, wherein the adhesive layer is a continuous layer having a porous structure and the adhesive layer comprises a vinylidene fluoride polymer. [22] Battery cell according to claim 21, characterized bythat the separator meets at least one of the following conditions: (1) the thickness of the base film is 7 to 9 µm; (2) the thickness of the ceramic layer on one side is 2 to 4 µm; (3) the thickness of the adhesive layer on one side is 1 to 5 µm. [23] Battery cell according to any one of claims 1 to 22, characterized by , that the active cathode material layer in a lower area facing the cathode current collector is provided with a lower coating that meets at least one of the following conditions: (1) the lower coating comprises a conductive agent and a binder, wherein the conductive agent comprises a carbon nanotube and a conductive carbon black, and the binder comprises polyvinylidene fluoride; (2) the thickness of the lower coating is 0.5 µm to 5 µm. [24] Battery cell according to any one of claims 1 to 23, characterized by, that the cathode foil and the anode foil are stacked alternately along the thickness direction of the battery cell; wherein the separator forms a continuous spiral structure or a continuous Z-shaped structure, wherein the separator is arranged to pass through between the cathode foil and the anode foil, which are adjacent to each other, in order to separate the cathode foil and the anode foil, which are adjacent to each other. [25] Battery cell according to any one of claims 1 to 24, characterized by , that the battery cell further comprises a shell, wherein the laminated battery cell is received in the shell, the shell being made of a soft packaging material, the soft packaging material comprising an aluminium-plastic composite film, optionally a composite film of aluminium and one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, nylon, polyethylene terephthalate, polyethylene. [26] Battery cell according to any one of claims 1 to 25, characterized by , that the size of the shell in the longitudinal direction is L1 and the size of the shell in the width direction is W1, where the size of the shell in the thickness direction is H1, where 450 mm ≤ L1 ≤ 1300 mm and 100 mm ≤ W1 ≤ 150 mm; where 14 mm ≤ H1 ≤ 22 mm. [27] Battery cell according to claim 26, characterized by , that the size of the shell in the longitudinal direction is L1, where 450 mm ≤ L1 ≤ 650 mm. [28] Battery cell according to claim 26, characterized by , that the size of the shell in the longitudinal direction is L1, where 900mm ≤ L1 ≤ 1300mm. [29] Battery cell according to any one of claims 1 to 28, characterized by , that the lithium-containing transition metal phosphate particles comprise components that are represented by the following general formula: Li m Fe x P y O j Q q Formula 1 where Q comprises one or more of Al, Na, K, Mg, Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb, V, Ti, B, S, Si, N, F, Cl, Br, where 0.8 ≤ m ≤ 1.15, 0.9 ≤ x ≤ 1, 0.95 ≤ y ≤ 1, 3.5 ≤ j ≤ 4, 0 < q ≤ 0.

1. [30] Battery device, characterized by that the battery device comprises a battery cell according to any one of claims 1 to 29. [31] Battery device according to claim 30, characterized by , that the battery device further comprises a housing, wherein several battery cells are stacked in a row along the thickness direction and glued into the housing; wherein a reinforcing partition plate is provided between the large surfaces of the shells of two adjacent battery cells, the reinforcing partition plate being connected to the housing, the stiffness of the reinforcing partition plate being greater than the stiffness of the shell of the battery cell. [32] Battery device according to claim 31, characterized by, that two reinforcing separating plates, arranged side by side along the thickness direction and distributed on both sides of at least one battery cell in the thickness direction, are connected to each other by a connecting plate located in the outer circumferential area of ​​the battery cell. [33] Battery device according to claim 32, characterized by , that the connecting plate is arranged between the two reinforcing partition plates connected to it and is connected to the two reinforcing partition plates to form a U-shaped shell. [34] Power-consuming device, characterized by that the power-consuming device comprises a battery device according to one of claims 30 to 33, wherein the battery device is used to provide electrical energy. [35] Energy storage device, characterized by, that the energy storage device comprises a battery device according to one of claims 30 to 33, wherein the battery device is used to store electrical energy.

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