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

Abstract

Battery cell characterized in that it comprises a stacked electrical core, wherein the stacked electrical core comprises a cathode foil and an anode foil, wherein the cathode foil comprises a cathode collector and a cathode film layer provided on at least one side of the cathode collector, wherein the cathode film layer comprises lithium-containing transition metal phosphate particles, wherein at least a part of the surface of the lithium-containing transition metal phosphate particles is provided with a carbon material; where the percentage area fraction of particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%; wherein the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 3.0%-15.0%; where the density of the cathode foil when the battery cell is in a fully discharged state is 2.3 g / cm³ 3 -2.6 g / cm² 3 amounts.

Description

TECHNICAL AREA

[0001] The present application relates to the technical field of battery cells, in particular a battery cell, a battery device, a power-consuming device and an energy storage device. STATE OF THE ART

[0002] 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 a variety of fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0003] With the market's demand for range and lifespan of power-consuming devices doubling, the requirements for battery cell energy density and cycle life have also increased. However, achieving simultaneous improvements in these performance levels with current technology is difficult, making it a technical problem that urgently needs to be addressed in this field. DISCLOSURE OF REGISTRATION

[0004] The present application is made in view of the aforementioned subject matter with the purpose of providing a battery cell with high capacity and good cycle performance.

[0005] A first aspect of the present application provides a battery cell comprising a stacked electrical core, wherein the stacked electrical core comprises a cathode foil and an anode foil, wherein the cathode foil comprises a cathode collector and a cathode film layer provided on at least one side of the cathode collector, wherein the cathode film layer comprises lithium-containing transition metal phosphate particles, wherein at least a part of the surface of the lithium-containing transition metal phosphate particles is provided with a carbon material; wherein a percentage area fraction of the particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%;wherein the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 3.0%-15.0%; wherein a density of the cathode foil when the battery cell is in a fully discharged state is 2.3 g / cm²; 3 -2.6 g / cm² 3 amounts.

[0006] Research has shown that effectively increasing the electrode film density requires incorporating a sufficient number of particles with a size greater than or equal to 1 µm into the cathode film layer. The applicant found that if the percentage area fraction of particles with a size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode film is less than 12%, or if the percentage area fraction of particles with a size of 50 nm–200 nm is less than 3%, this results in insufficient particle gradation, limiting the improvement in density and thus preventing an effective increase in battery capacity. If the cathode film density is less than 2.3 g / cm³ 3When the battery monomer is fully discharged, not only is it difficult to achieve the ideal capacity performance, but the formation of the electron conduction network and the lithium-ion transfer channel is also hindered due to insufficient contact between the particles, significantly increasing the battery's internal resistance. If the percentage of surface area covered by particles with a size of 50 nm–200 nm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil exceeds 15%, this high surface area of ​​small particles leads to an increase in the internal resistance of the cathode film layer, exacerbates the battery's heat generation during the cycling process, and degrades its cycle performance.If the area fraction of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is more than 50% or the compression density of the cathode foil in a fully charged state of the battery cell is more than 2.6 g / cm. 3 If the large particles are compressed, they will create an obvious stress concentration effect, leading to failure of contact between the particles, loosening of the structure of the film layer and even the deposition of the active substance, thus negatively impacting cycle performance.

[0007] The embodiments of the present application improve the battery capacity through the structural design of the stacked electrical core and the optimization of the particle size distribution of the lithium-containing transition metal phosphoric acid cathode film layer. Simultaneously, by reducing the area fraction of the large particles and controlling the compression density of the cathode film, the voltage concentration of the large particles during the pressing process of the electrode film in the stacked electrical core is improved, effectively mitigating the problems of film layer structure loosening and active substance deposition, and improving the battery's cycle performance.The surface area of ​​the small particles is regulated within a suitable range, ensuring not only sufficient particle density but also preventing an increase in the resistance of the cathode film layer due to an excessive number of small particles. This reduces heat generation during the battery's cycling process and improves its kinetic and cycle performance. The synergistic design of a stacked electrical core and cathode film enhances the battery's capacity, cycle performance, and kinetic power.

[0008] In each embodiment, the percentage area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%.

[0009] The area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil lies within the above range, which is beneficial to maintaining the high capacity of the battery and further improves the phenomena of film layer loosening and active substance deposition caused by the tension concentration of large particles during electrode foil compression, in order to improve the cycle performance of the battery.

[0010] In each embodiment, the percentage area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-40%.

[0011] The area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil lies within the above range, which is beneficial to maintaining the high capacity of the battery and further improves the phenomena of film layer loosening and active substance deposition caused by the tension concentration of large particles during the pressing of the electrode foil, in order to further improve the cycle performance of the battery.

[0012] In each embodiment, the uniformity of the particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 0.2%-5%, optionally 0.2%-2%.

[0013] The distribution uniformity of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is within a suitable range, and the uniformly distributed large particles can effectively reduce the stress concentration in a local area of ​​the film layer, so that the stress in the pressing process of the film layer is distributed uniformly over the entire area of ​​the film layer, thereby avoiding the phenomenon of local stress concentration caused by particle agglomeration and reducing the probability of the film layer delaminating, thus improving the cycle performance of the battery.

[0014] In each embodiment, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median L is A50 sphericity 0.6-0.8.

[0015] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, and the larger particles have better sphericity, which reduces particle bridging due to the irregular shape of the large particles, reduces the void content in the electrode foil and simultaneously reduces the voltage concentration, which is exacerbated by the irregularity of the large particles, which improves the phenomena of film layer loosening and active substance deposition, and the battery cell exhibits high capacity and good cycle performance.

[0016] In each embodiment, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median L is A50 sphericity 0.65-0.75.

[0017] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, which contributes to reducing the stress concentration during the pressing of the electrode foil, which is exacerbated by the irregularity of the large particles, and to improving the phenomenon of film layer loosening and active substance fallout.

[0018] In each embodiment, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median L is A50 sphericity 0.67-0.75.

[0019] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, which helps to further improve the voltage concentration of the large particles during the pressing of the electrode foil, reduce the probability of loosening of the film layer and drop-off of the active substance, and improve the cycle time of the battery cell.

[0020] In each embodiment, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 5.0%-15.0%.

[0021] The area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is within the above range, the cathode film layer has an appropriate amount of small particles, thus ensuring a sufficient particle fill level, while avoiding the negative effect on the resistance of the film layer caused by an excessively large area fraction of small particles, and the battery improves the kinetic performance of the battery based on a good capacity.

[0022] In each embodiment, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 5.0%-10.0%.

[0023] The area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is within the above range, the cathode film layer exhibits good particle gradation, the specific resistance of the cathode film layer is further reduced, and the kinetic performance of the battery is further improved on the basis of good capacity.

[0024] In each embodiment, the one-sided thickness of the cathode film layer is 70 µm-120 µm.

[0025] The gram capacity of lithium-containing transition metal phosphate particles is relatively low, and research has shown that it is difficult to meet market demand when the one-sided thickness of the cathode film layer is less than 70 µm. The one-sided thickness of the cathode film layer is within the range mentioned above, which contributes to improving the battery cell's capacity.

[0026] In each embodiment, the one-sided thickness of the cathode film layer is 90 µm-120 µm.

[0027] The thickness of the cathode film layer on one side is within the range above, which contributes to a further improvement in the capacity of the battery cell.

[0028] In each embodiment, the one-sided thickness of the cathode film layer is 100 µm-120 µm.

[0029] Increasing the thickness of the cathode film layer on one side contributes to improving the battery's capacity, and the applicant has found that the cathode film layer is more prone to film loosening and active substance deposition when the thickness of the cathode film layer on one side is greater than or equal to 100 µm. The embodiments of the present application reduce the area fraction of large particles and the density of the cathode film layer, thereby improving the phenomenon of stress concentration of large particles during the pressing of the electrode foil in the stacked electrical core. At the same time, an appropriate amount of small particles is added, so that the electrode foil has a further improved density based on a certain content of large particles, and the battery exhibits improved capacity and cycle performance.

[0030] In each embodiment, the cathode film layer further comprises a conductive agent, wherein, with respect to the total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the proportion of the total area of ​​an agglomeration region of the conductive agent is 0.2%-6%, optionally 1.5%-5%.

[0031] Based on the total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the total area of ​​the agglomeration region of the conductive agent lies within the above range, indicating that the conductive agent is uniformly dispersed in the cathode film layer and that it is easy to form a homogeneous conductive network, which helps to reduce local polarization or even lithium precipitation of the battery during the cycling process.

[0032] Simultaneously, the corresponding quantity of small particles in the present application can be used as a basic conductive skeleton to fill the gap left by the large particles, while the dispersed agglomerates of the conductive agent are used as nodes for long-range conduction to form a graded conductive structure; due to the lithium-containing transition metal phosphate particles in the large particles being easily rebounded, the agglomeration area of ​​the conductive agent in the above area can also be able to inhibit the rebound of the large particles by means of the uniform distribution of the conductive agent to form a mechanical bond between the particles and even the film layer, improving the cohesion of the film layer, reducing powder fallout from the film layer, reducing the phenomenon of active substance deposition, and improving the battery lifetime.

[0033] In each embodiment, the conductive means comprises carbon nanotubes, wherein the carbon nanotubes comprise one or more of single-walled carbon nanotubes, thin-walled carbon nanotubes, multi-walled carbon nanotubes, wherein the conductive means further optionally comprises conductive carbon black.

[0034] Carbon nanotubes have a high length-to-diameter ratio, which, due to their unique fiber structure, bridges particles of different sizes in the thickness direction, forming a long-distance conductive path and simultaneously improving the binding force between the particles, reducing local polarization and even lithium precipitation during the battery cycle and improving the battery's lifespan; furthermore, the rebound phenomenon of large particles in the cathode film layer is reduced by the binding effect, thereby decreasing the phenomenon of active substance deposition in the film layer.

[0035] Conductive carbon black is small in size, adheres to the surface of the cathode particles, and fills the gaps between them, creating a dense, point-like conductive contact. The combination of carbon nanotubes and carbon black further enhances the conductive network within the cathode film layer, addressing both long-range and short-range conductivity. Simultaneously, the conductive material has a large specific surface area, which facilitates the absorption and retention of electrolyte solution. This reduces the phenomenon of electrolyte extrusion, caused by the significant increase in electrode film expansion during extended cycles, and can thus improve battery lifespan.

[0036] In each embodiment, the agglomeration area of ​​the conductive agent comprises carbon nanotubes and conductive carbon black.

[0037] The researchers found that carbon nanotubes, due to their high surface energy, tend to agglomerate, leading to an uneven distribution in the cathode film layer and preventing the formation of an effective network structure. Conductive carbon black, with a surface energy close to that of carbon nanotubes, can be adsorbed onto their surface to form a physical barrier. This increases resistance to agglomeration, reduces direct contact between the nanotubes, and thus inhibits agglomeration, thereby improving the uniformity of carbon nanotube distribution within the cathode film layer.On the one hand, this helps to improve the electrical conductivity of the cathode film layer and the kinetic performance of the battery; on the other hand, it helps to exert the binding effect of the carbon nanotubes on the cathode film layer, reducing the risk of cathode film delamination and further improving the kinetic performance and lifetime of the battery. Furthermore, the agglomeration of carbon nanotubes in the agglomeration region of the conductive medium also blocks the local ion transfer pathway in this region, and the collocation of conductive carbon black can improve the lithium-ion transfer capacity in this region, reduce local polarization, and further improve the cycle stability of the battery.

[0038] In each embodiment, the mass fraction C1 of the carbon nanotubes, relative to the mass of the cathode film layer, is 0. <C1≤2,5% und der Massengehalt C2 des leitfähigen Rußes 0<C1≤2,5%.

[0039] The mass content of carbon nanotubes and conductive carbon black within the above range can effectively reduce the agglomeration phenomenon of carbon nanotubes and form a good conductive network structure, thereby effectively reducing the voltage concentration of the cathode film layer and improving the retention rate of electrolyte solution of the cathode film layer during long cycles, thereby further reducing the risk of electrode foil film layer delamination and the degree of polarization, increasing the kinetic performance of the battery and improving the cycle life of the battery.

[0040] In each embodiment, the cathode film layer further comprises a dispersing agent, wherein the dispersing agent comprises hydrogenated nitrile butadiene rubber HNBR.

[0041] The polar groups (e.g., cyano group, -CN) in the HNBR hydrogenated nitrile butadiene rubber molecule can interact with the hydroxyl group (-OH) or the metal oxide sites on the surface of the lithium-containing transition metal phosphate particles (e.g., hydrogen bonding, dipole effect) to improve particle compatibility with the solvent and reduce interfacial tension between the particles and the solvent. This improvement in interfacial tension is even more pronounced for large particles. In this way, the large and small particles can be dispersed more easily and uniformly in the film layer, thereby reducing particle aggregation due to hydrophobicity, improving the dispersion of large particles in the cathode film layer, and lowering the concentration of stresses generated during film stamping.

[0042] When the slurry is dried to form a film, the elastic network structure of HNBR can buffer the shrinkage stress caused by solvent evaporation, rearrange the conductive agent during the process due to capillary action, and reduce the area fraction of the conductive agent's agglomeration zone. The uniform distribution of the conductive agent is beneficial for inhibiting the rebound of large particles, forming mechanical constraints on the particles and even the film layer, improving film layer cohesion, reducing powder shedding from the film layer, minimizing active substance deposition, and extending battery life.

[0043] In each embodiment, the mass content of the conductive medium is 0.5%-2%, based on the mass of the cathode film layer.

[0044] The mass fraction of the dispersant is within the above range, which allows for a uniform dispersion of the particles in the cathode film layer, while maintaining a high charge capacity in the cathode film layer, and ensuring that the battery has good capacity and cycle performance.

[0045] In each embodiment, the cathode film layer is provided with a lower coating layer at a lower area facing the cathode collector, the lower coating layer comprising a conductive agent and a binder, wherein the conductive agent comprises carbon nanotubes and conductive carbon black, and the binder comprises a vinylidene fluoride polymer.

[0046] In each embodiment, the cathode film layer is provided with a lower coating layer on a lower area facing the cathode collector; the thickness of the lower coating layer is 0.5 µm-5 µm.

[0047] The lower coating layer provided in the embodiments of the present application contributes to improving the adhesion between the cathode film layer and the cathode collector and to reducing the phenomenon of voltage concentration at the large particles, thereby decreasing the probability of cathode film layer delamination and improving the cycle stability of the battery. At the same time, compared to direct contact between the cathode collector and the cathode film layer, the contact area between the lower coating layer and the cathode film layer is increased, which contributes to increasing the electron transfer area between the collector and the cathode film layer, thereby reducing the internal resistance of the electrode foil and improving the kinetic performance of the battery.

[0048] In each embodiment, the median is C 50of the degree of graphitization in the cumulative distribution curve for a graphitization C value of the cathode film layer obtained in an area scanning mode of the laser microconfocal Raman spectrometer, is greater than 0.95 and less than or equal to 1.20; where the graphitization C value I G / I D is, where I G for the intensity of the G-peak of the Raman spectrum at 1580±100cm -1 and I D for the intensity of the D-peak of the Raman spectrum at 1350±100cm -1 stands.

[0049] In the cumulative distribution curve of the graphitization C-value of the cathode film layer, obtained in an area-scanning mode of the laser microconfocal Raman spectrometer, the median C50 of the graphitization degree lies within the range mentioned above. Therefore, the electrode foil density can be further improved by particle slippage without unduly affecting the proportion of large and small particles in the cathode film layer. This keeps the area fraction of large and small particles within a suitable range, reducing the probability of cathode film layer delamination and preventing excessive resistance. This, in turn, improves the battery's cycle life and kinetic performance while maintaining battery capacity.

[0050] In each embodiment, the lithium-containing transition metal phosphate particles in the cathode film layer comprise a component with a general formula as follows: LimFe x P y O j Q q , 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, and where 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, 0 <q≤0,1 ist.

[0051] In each embodiment, the lithium-containing transition metal phosphate particles comprise titanium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of titanium is 500 ppm-8000 ppm, optionally 1000 ppm-3000 ppm.

[0052] When titanium is doped into the lithium-containing transition metal phosphate particles, the resulting Ti-OP bond exhibits a strong bonding interaction that reduces the contraction / expansion amplitude of the lattice by anchoring the phosphate group when lithium ions are unembedded, thereby suppressing the structural stress induced by the phase transition and contributing to improved battery cycle life; furthermore, the Ti-OP bond can form a more stable channel for lithium ion diffusion, thereby lowering migration barriers and contributing to improved battery kinetic performance.

[0053] The mass content of titanium within the above range contributes to improving the lithium ion transfer rate of the active cathode material, reduces the risk of lithium precipitation, and improves the kinetic performance of the battery.

[0054] In each embodiment, the lithium-containing transition metal phosphate particles comprise vanadium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of vanadium is 500 ppm-5000 ppm, optionally 500 ppm-3000 ppm.

[0055] When vanadium is doped in lithium-containing transition metal phosphate particles, it exhibits multivalent properties. When +5-valent vanadium (V) 5+ When doped with phosphorus sites, its larger radius leads to lattice distortions, enlarges the lithium-ion diffusion channels, and improves the ionic conductivity of the active cathode material; when +3-valent vanadium (V 3+ ) is doped with transition metal sites, the charge is compensated by lithium gaps or interstitial oxygen, creating defect energy levels and improving the electronic conductivity of the active cathode material.

[0056] The mass content of vanadium within the above range contributes to improving the lithium ion transfer rate of the active cathode material, improving the electron conductivity of the active cathode material, and further improving the kinetic performance of the battery through the synergistic effect with doping with titanium.

[0057] In each embodiment, the porosity of the cathode film layer is 14%-28%.

[0058] The porosity of the cathode film layer lies within the above range, which means that the cathode film layer has a better gradation of large and small particles, and it is conducive to improving the properties of the liquid retention of the electrolyte solution, improving the ion diffusion capability of the cathode film layer with a certain area fraction of large particles, and improving the kinetic performance of the battery.

[0059] In each embodiment, the specific resistance of the cathode film layer is 10 Ω·cm to 35 Ω·cm.

[0060] The specific resistance of the cathode film layer is in a suitable range, which contributes to reducing the impedance of electron transfer, reducing charge / discharge polarization, and improving the kinetic performance of the battery.

[0061] In each embodiment, the battery cell further comprises a separator arranged between the cathode foil and the anode foil, wherein the separator comprises a base film, a ceramic layer provided on both sides of the base film, and a bonding layer provided on at least one of the sides of the ceramic layer facing away from the base film, wherein the bonding layer is a continuous layer with a porous structure, and wherein the bonding layer comprises a vinylidene fluoride polymer.

[0062] The separator provided by the embodiments of the present application uses a continuous layer with a porous structure as a bonding layer, which has a larger bonding area than the island-shaped bonding layer in the prior art, thereby making the bond between the separator and the cathode film layer stronger and more uniform, and at the same time, by means of a pore structure in the bonding layer, it can combine both the lithium-ion transfer efficiency and the kinetic performance of the battery.Simultaneously, the compression force between the electrode foils of the stacked electric core is low compared to the wound electric core during the manufacturing process. Furthermore, the lithium-containing transition metal phosphate particles with a particle size of 1 µm or greater reduce the compactness of the internal components of the electric core during the rebound process, improve the impedance of the electric core, and increase the likelihood of the film layer precipitating into powder or even detaching. The separator provided by the embodiments of the present application uses a continuous layer with a porous structure as a bonding layer, which is particularly suitable for the stacked electric core, improves the rebound phenomenon of the stacked electric core during long cycles, and enhances the retention of battery capacity during long cycles.

[0063] The embodiments of the present application use the continuous layer with the porous structure as a bonding layer to improve the bonding strength between the separator and the electrode foil while maintaining the permeability and porosity of the separator, to improve the stability of the electrode foil, to further reduce the risk of powder falling due to the relative displacement of the electrode foil and the separator or even the occurrence of an internal short circuit, and to improve the cycle stability of the battery.

[0064] In each embodiment, the battery cell comprises a housing wherein the stacked electrical core is received in the housing, wherein the housing has a dimension of L0 in a longitudinal direction, wherein the housing has a dimension of WO in a width direction, wherein the housing has a dimension of H0 in a thickness direction, wherein 450 mm ≤ L0 ≤ 1300 mm, 100 mm ≤ W0 ≤ 150 mm, and 14 mm ≤ H0 ≤ 22 mm.

[0065] The dimensions of the housing of the battery cell of the embodiments of the present application are within the above range, which contributes to achieving a better battery capacity.

[0066] In each embodiment, the dimension L0 of the housing in the longitudinal direction satisfies the following condition: 450 mm ≤ L0 ≤ 650 mm.

[0067] If the length dimension L0 of the casing is 450 mm ≤ L0 ≤ 650 mm, the battery cell has a shorter length, which contributes to shortening the electron transfer path and reducing the internal resistance of the battery, while simultaneously reducing the infiltration distance of the electrolyte solution in the pores of the electrodes, improving the uniformity of the infiltration and increasing the kinetic power of the battery; in particular under fast charging conditions, it can reduce the phenomenon of uneven temperature rise and current density in the length direction of the electrode foil.

[0068] In each embodiment, the dimension L0 of the housing in the longitudinal direction satisfies the following condition: 900 mm ≤ L0 ≤ 1300 mm.

[0069] The longitudinal dimension L0 of the housing meets the following condition: 900 mm ≤ L0 ≤ 1300 mm. A significant increase in the battery cell dimensions can effectively simplify the traditional module structure, allowing the battery cell to be directly integrated into the battery pack. Battery mounting is achieved via structural components at the end section of the large surface area, which significantly improves space utilization and thus increases the overall capacity of the battery system for the same volume, while simultaneously reducing the number of structural components and improving the battery's energy density.

[0070] In each embodiment, the housing material is a soft packaging material, wherein the soft packaging material comprises an aluminum-plastic composite film, optionally comprising a composite film formed from one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), polyethylene (PE) with aluminum.

[0071] The soft packaging material has high elongation, and its casing is thin and soft, which contributes to better space utilization of the battery system and thus increases the energy density of the battery system; however, the soft packaging material, such as aluminum-plastic composite foils, has poor thermal conductivity, which leads to low heat dissipation efficiency of the soft-pack battery. Therefore, if the surface area fraction of the small particles in the cathode film layer is too large, the specific resistance of the cathode film layer increases, leading to excessive heat production in the battery during the cycling process and further exacerbating the problem of poor heat dissipation in the soft-pack battery.By using the soft packaging material as the casing and controlling the area fraction of the small particles in the cathode film layer within a suitable range, the battery of the embodiments of the present application has a high capacity and good cycle performance.

[0072] In each embodiment, the housing comprises a first sealing zone, wherein the first sealing zone is provided at at least one end extending in the width direction of the stacked electrical core; wherein the first sealing zone comprises a folded edge structure extending in the length direction, wherein the folded edge structure is provided with an encapsulating adhesive, wherein the encapsulating adhesive is provided successively along the length direction and secures the folded edge structure.

[0073] The embodiments of the present application further improve the sealing strength of the first sealing zone by incorporating a folded edge structure extending along the longitudinal direction within the first sealing zone. The encapsulation adhesive is continuously applied along the longitudinal direction and secures the folded edge structure, in contrast to discontinuous application of the encapsulation adhesive along the longitudinal direction. This further improves the encapsulation strength, achieves continuous reinforcement of the sealing zone in the longitudinal direction, and reduces the likelihood of the electrode foil popping out of the sealing zone of the packaging during the cycle process.

[0074] In each embodiment, the housing comprises at least one second sealing zone, wherein the second sealing zone is provided at at least one end of the stacked electrical core extending along the longitudinal direction of the housing, and wherein the second sealing zone is provided on one side of the electrode tab of the stacked electrical core.

[0075] The second sealing zone is located on the side of the electrode tab; the electrode tab must be connected to a lead element, and the connection strength of the lead element and the housing material is relatively weak, so that the gas can easily be flushed out of the second sealing zone, which contributes to achieving a directed pressure relief of the battery, reducing the effects of thermal runaway on the adjacent electrical core, and improving the overall lifespan of the battery.

[0076] In each embodiment, a plurality of adhesive rings circumferentially arranged in the width direction are provided around an outer circumference of the stacked electrical core, wherein the adhesive rings circumferentially arranged in the width direction are provided at intervals along the length direction.

[0077] The spaced arrangement of the adhesive rings in the longitudinal direction, which surround the electrical core along the width direction, is beneficial for fixing the position between the electrode foils in the electrical core and reducing the probability of displacement of the electrical core when the battery is shaken. This is particularly suitable for long batteries, which can effectively reduce displacement between the electrode foils in the longitudinal direction and lead to the phenomenon of lithium precipitation. It is also beneficial for keeping the internal spatial structure of the battery stable, so that it does not affect the normal operation of the battery.

[0078] In each embodiment, the battery cell capacity at 25°C is 100 Ah-300 Ah, optionally 110 Ah-190 Ah, and further optionally 125 Ah-180 Ah.

[0079] In the battery cell of the embodiments of the present application, a suitable housing dimension is set to accommodate the stacked electrical core, and an appropriate proportion of large particles in the film layer of the electrode foil in the stacked electrical core is controlled so that the battery cell has a high capacity.

[0080] A second aspect of the present application provides a battery device comprising a battery cell according to the first aspect of the present application.

[0081] A third aspect of the present provides a power-consuming device, wherein the power-consuming device comprises a battery device according to the second aspect, wherein the battery device is used to provide electrical energy.

[0082] A third aspect of the present provides an energy storage device, wherein the energy storage device comprises a battery device according to the second aspect, wherein the battery device is used to store electrical energy. PRESENTATION OF THE REGISTRATION Fig. Figure 1 is a schematic representation of a separator in an embodiment of the present application; Fig. Figure 2 shows a schematic representation of a separator in the prior art; Fig. Figure 3 is a schematic representation of a surface morphology of a bonding layer of the separator of an embodiment of the present application; Fig. 4 is a front view of a battery cell in an embodiment of the present application; Fig. Figure 5 shows a schematic representation of a power-consuming device in an embodiment of the present application. Reference symbol list:

[0083] 20 Separator; 201 Base film; 202 Ceramic layer; 203 Bonding layer; 5 Battery cell; 50 Housing; 51 First sealing zone; 52 Second sealing zone; 53 Leading element; X Longitudinal direction; Y Width direction; Z Thickness direction. SPECIFIC EXECUTION FORMS

[0084] The following sections disclose in detail embodiments of the battery cell, battery device, power-consuming device, and energy storage device of the present application with corresponding reference to the accompanying drawings. However, there will be instances where an unnecessarily detailed description is omitted. For example, detailed descriptions of things that are already well known and repeated descriptions of the same structure will be left out. This is to avoid making the following description unnecessarily long and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description serve to enable a person skilled in the art to fully understand the present application and are not intended to limit the subject matter specified in the claims.

[0085] The "range" disclosed here is defined in terms of a lower bound and an upper bound, with a particular range being defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60-120 and 80-110 is specified for a particular parameter, a range of 60-110 and 80-120 is also to be expected. Furthermore, if the minimum values ​​1 and 2 and the maximum values ​​3, 4, and 5 are specified, the following ranges can be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.Unless otherwise specified, the range "ab" denotes any combination of real numbers between a and b, where both a and b are real numbers. For example, the range "0-5" means that all real numbers between 0 and 5 are listed here, and 0-5 is simply a shorthand representation of the combination of these values. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to stating that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on.

[0086] Unless expressly stated otherwise, all embodiments and optional embodiments of the present application may be combined to form new technical solutions, and such a technical solution should be considered to be covered by the disclosure of the present application.

[0087] Unless expressly stated otherwise, all technical features of the present application, as well as optional technical features, may be combined to form a new technical solution, and such a technical solution should be considered to be covered by the disclosure of the present application.

[0088] Unless expressly stated otherwise, all steps of the present application may be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out one after the other, or that it may include steps (b) and (a) carried out one after the other. The indication that the method may also include step (c) means, for example, that step (c) may be added to the method in any order; e.g., the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b).

[0089] In the present application, the terms "plural" and "multiple" refer to two or more.

[0090] Unless otherwise stated, the terms used in this application have the known meanings as generally understood by those skilled in the art.

[0091] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be determined by various test methods commonly used in practice, e.g., according to the test methods specified in the embodiments of this application. Unless otherwise specified, the test temperature for each parameter is 25°C.

[0092] The battery devices in the embodiments of the present application can comprise one or more battery cells to provide a voltage and capacity. The battery cell assembly can comprise a plurality of soft-pack battery cells, wherein the plurality of soft-pack battery cells are connected in series, parallel, or in a mixed configuration by a converging element. For example, the battery cell assembly is typically formed by arranging a plurality of soft-pack battery cells; the battery cell assembly can be a battery module, wherein the battery module comprises a plurality of soft-pack battery cells arranged and secured to form a single module. For example, the battery module can be formed by bonding the multiple battery cells together.

[0093] The battery device can be a battery pack comprising a housing and one or more battery cell assemblies, with the battery cell assemblies being 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 securing the battery module within the housing; the battery cell assembly can also be contained within the housing by directly securing a plurality of soft-packed battery cells within the housing.

[0094] In the embodiments of the present application, the box can comprise a first box and a second box. The first box and the second box are attached to one another in such a way that an enclosed space is formed inside the box, which accommodates the battery cell assembly. "Enclosed" here means covered or sealed, and this space may be sealed or unsealed. The first box can be a top cover or a bottom plate. For example, the box 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 an enclosed space is formed inside the box, which accommodates the battery cell assembly.

[0095] In the embodiments of the present application, the box can be part of a chassis structure of the vehicle. For example, parts of the box can be at least part of a floor of the vehicle, or parts of the box can be at least part of a cross member and a longitudinal member of the vehicle.

[0096] In the embodiments of the present application, the battery cell can be a secondary battery, i.e., a battery cell that can be recharged after it has been discharged, so that the active material can be reactivated and reused; the battery cell can be a lithium-ion battery. The battery cell can be flat.

[0097] The batteries mentioned in the embodiments of the present application can comprise one or more battery cells to achieve a higher voltage and capacity. The batteries mentioned in the present application can be, for example, battery cells, battery modules, or battery packs.

[0098] The battery cell is the smallest unit that makes up the battery and is capable of performing the charging and discharging functions on its own. In the case of multiple battery cells, the cells are connected in series, parallel, or a mixed configuration via a sink component. In some embodiments, the battery may be a battery module; in the case of multiple batteries, the cells are arranged and secured to form a single module. In some embodiments, the battery may be a battery pack comprising a housing and a battery cell, with the battery cell or battery module contained within the housing. In some embodiments, the housing may be part of the vehicle's chassis structure.For example, parts of the housing can be at least part of a chassis of the vehicle, or parts of the housing can be at least part of a cross member and a longitudinal member of the vehicle.

[0099] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, and the like.

[0100] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells contained in the battery module can be multiple, with the exact number being adjustable depending on the application and capacity of the battery module. In some embodiments, the battery modules described above can also be assembled into a battery pack, with the number of battery modules contained in the battery pack being adjustable depending on the application and capacity of the battery pack.

[0101] The battery cell comprises an electrode component and an electrolyte.

[0102] The electrode component typically comprises a cathode foil and an anode foil, the anode foil being the electrode where the reaction of uptake or lithiation of lithium ions during charging and release or delthiation of lithium during discharging takes place, and the cathode foil being the electrode where the reaction of release or delthiation of lithium ions during charging and uptake or lithiation of lithium during discharging takes place.

[0103] Lithium-containing transition metal phosphate materials offer significant advantages over lithium-containing transition metal oxide materials, such as increased safety, longer cycle life, lower raw material costs, and better stability at high temperatures. However, these materials also have inherent drawbacks, particularly their lower theoretical gram capacity, which severely limits the potential for increasing battery capacity.The applicant found that the stacked electric core, compared to the wound electric core, has no corner area and offers higher space utilization of the battery's internal volume. Furthermore, the use of the stacked electric core contributes to improving the battery's volumetric energy density. Increasing the proportion of large and small particles and optimizing the particle gradation of the active cathode material can further improve the electrode film's pressing density and the battery's volumetric energy density. However, during the electrode film pressing process, large particles tend to form stress concentrations, leading to contact defects between particles, loosening of the film layer structure, and even active substance deposition. While small particles can fill the gaps to further improve the electrode film's pressing density, excessively small particles increase the resistance of the cathode film layer.In stacked electrical cores, the radial bonding force is lacking because there is no bond from one corner region to another. This exacerbates the phenomenon of film delamination in the electrode foil due to the stress concentration generated by the large particles. This film delamination leads to a reduction in battery capacity, an internal micro-short circuit, and worsens the electrolyte solution's side reactions, negatively impacting battery performance. The engineering problem of how to develop a battery that exhibits good capacity, cycle life, and kinetic energy must be solved within this field of engineering.

[0104] A first aspect of the present application provides a battery cell comprising a stacked electrical core, wherein the stacked electrical core comprises a cathode foil and an anode foil, wherein the cathode foil comprises a cathode collector and a cathode film layer provided on at least one side of the cathode collector, wherein the cathode film layer comprises lithium-containing transition metal phosphate particles, wherein at least a part of the surface of the lithium-containing transition metal phosphate particles is provided with a carbon material; wherein a percentage area fraction of the particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%;wherein the percentage area fraction of particles with a particle size of 50 nm-200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 3.0%-15.0%; wherein a compression density of the cathode foil when the battery cell is in a fully discharged state is 2.3 g / cm²; 3 -2.6 g / cm² 3 amounts.

[0105] Research has shown that effectively increasing the electrode film's density requires incorporating a sufficient quantity of particles with a size greater than or equal to 1 µm into the cathode film layer. The applicant found that the loss of electrode film density due to the lower proportion of large particles can be compensated for by adding a sufficient quantity of small particles. Furthermore, if the percentage area fraction of particles with a size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode film is less than 12%, or if the percentage area fraction of particles with a size of 50 nm–200 nm is less than 3%, this results in insufficient particle gradation, limiting the improvement in density and thus preventing an effective increase in battery capacity.If the density of the cathode foil is less than 2.3 g / cm³. 3When the battery monomer is fully discharged, not only is it difficult to achieve the ideal capacity performance, but the formation of the electron conduction network and the lithium-ion transfer channel is also hindered due to insufficient contact between the particles, significantly increasing the battery's internal resistance. If the percentage of surface area covered by particles with a size of 50 nm–200 nm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil exceeds 15%, this high area fraction of small particles leads to an increase in the internal resistance of the cathode film layer, exacerbates the battery's heat generation during the cycling process, and degrades its cycle performance.If the area fraction of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is more than 50% or the compression density of the cathode foil in a fully charged state of the battery cell is more than 2.6 g / cm. 3 If the large particles are compressed, they will create an obvious stress concentration effect, leading to failure of contact between the particles, loosening of the structure of the film layer and even the deposition of the active substance, thus negatively impacting cycle performance.

[0106] The embodiments of the present application improve the battery capacity through the structural design of the stacked electrical core and the optimization of the particle size distribution of the lithium-containing transition metal phosphoric acid cathode film layer. Simultaneously, by reducing the area fraction of the large particles and controlling the compression density of the cathode film, the voltage concentration of the large particles during the pressing process of the electrode film in the stacked electrical core is improved, effectively mitigating the problems of film layer structure loosening and active substance deposition, and improving the battery's cycle performance.The surface area of ​​the small particles is regulated within a suitable range, ensuring not only sufficient particle density but also preventing an increase in the resistance of the cathode film layer due to an excessive number of small particles. This reduces heat generation during the battery's cycling process and improves its kinetic and cycle performance. The synergistic design of a stacked electrical core and cathode film enhances the battery's capacity, cycle performance, and kinetic power.

[0107] In the present application, the stacked electrical core refers to an electrical core formed by stacking a cathode foil, a separator and an anode foil.

[0108] The lithium-containing transition metal phosphate particles refer to a phosphate material comprising lithium and a transition metal element and can be detected by any known method in this field. For example, it can be detected by a combination of X-ray diffraction (XRD) and X-ray diffraction.

[0109] It should be noted that the cathode film layer comprises lithium-containing transition metal phosphate particles, but the cathode film layer does not refer only to the active cathode material layer, and other film layers associated with the active cathode material layer and difficult to distinguish from it, such as the sublayer, the liquid-retaining layer, and the like, are collectively referred to as the cathode film layer.

[0110] In the present application, the term "particle" refers to particles in the field of view of the cathode film layer at a certain magnification, e.g. 10,000x, with recognizable complete boundaries, whereby defects and scratches may be present within the particles, but no complete boundaries sufficient to subdivide the particles are recognizable within the particles.

[0111] The particle identification procedure is as follows: the cathode film layer is cut by the argon ion beam along the thickness direction of the electrode foil (for example, optional: instrument model: Leica EM TIC 3X CP, operating voltage: 6 kV, operating time: 6 h), and after exposing the cut surface, a scanning electron microscope is used (for example, optional: instrument model: Hitachi SU8230, operating voltage: 3 kV, beam current: high, probe model: U (LA100), working distance <5 mm) to observe the cut surface of the cathode film layer along the thickness direction of the electrode foil. The images are acquired with the field emission scanning electron microscope (FESEM) in the non-marginal position of the cut surface of the cathode film layer (after observing the edge of the electrode foil under the scanning electron microscope, the field of view is adjusted to the central part of the sample) in secondary electron mode.The electropherograms are acquired at 10k magnification, and the particles in the electropherograms are analyzed using ImageJ software (1.46r, Win64 version). The ImageJ software is used as follows: loading the scanning electron microscope image to be analyzed; identifying the particles using the Cellpose plug-in software and manually correcting them based on this identification; reading and counting the data using ImageJ. The specific procedure for using the Cellpose plug-in software to identify the particles is as follows: setting the segmentation diameter parameter (diameter in the segmentation module) to 15 pixels, clicking "run cyto3" to identify the particles; the particles in the image that are not identified, or not fully identified, or incorrectly identified by the software are manually marked. The particles in the image that are not identified, or not fully identified, or incorrectly identified by the software include:The most common reasons for misidentification are: 1. The particles are too large or have scratches on their surface, preventing or incomplete identification; 2. Scratches occur on the particle surface during the argon ion beam sectioning process, and the software may misinterpret these scratches as particle boundaries during identification, leading to an identification error; 3. The particles are too small and therefore cannot be successfully identified; 4. The particles are located at the edge of the electron microscope's field of view, and the edge penetrates the particle's interior, resulting in an incomplete morphology and the identification of only a localized portion instead of the entire particle, leading to an identification error. The aforementioned unidentified or incorrectly identified particles are calibrated manually.and the specific process is as follows: Delete the particles that are located at the edges of the scanning electron microscope environment and are not fully displayed; assess whether or not there is a slit scratch within the other unidentified or misidentified particles, and if there is no slit scratch within a particle, it is assessed as a single particle, and it is manually marked according to the manually observed boundaries of the particles; in response to the presence of a slit scratch within the particle, it is assessed whether the slit scratch runs through the particle, and if it does not run through the particle, it is assessed that it is a single particle, and it is manually marked; in response to the slit scratch running through the particle, it is assessed whether the slit scratch is linear or irregular; in response to the slit scratch being irregular,It is judged to be a boundary between the particles, and the particles are divided along the boundary; in response to the fact that the slit scratch is linear, a contrast comparison is performed; in response to the fact that the contrast comparison is not obvious and there is no cracking effect, the slit scratch is judged to be a scratch, and it is marked as one particle; in response to the fact that the contrast comparison is strong and there is a cracking effect, the slit scratch is judged to be a boundary between the particles, and it is marked as two particles. After manual marking, the information that is not related to the particles in the automatic processing of the image is deleted, i.e., the assessment and marking of the particles in the image is complete.

[0112] The percentage area fraction of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil can directly represent the ratio of the particle area in this particle size range to the total area of ​​the particles, which reflects the area of ​​the particles in this particle size range.

[0113] It is understood that in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the particles of 50 nm or more originate mainly from the active cathode material. Therefore, the embodiment of the present application can accurately and objectively reflect the distribution of the lithium-containing transition metal phosphate particles in the cathode film layer by observing and counting the particle area of ​​the particles in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil.

[0114] In the prior art, the particle size of the active cathode material is usually determined using a laser particle size analyzer based on the Malvern laser diffraction method. However, the applicant's research shows that, because the lithium-containing transition metal phosphate particles readily agglomerate, the test results obtained using the Malvern laser diffraction method based on the laser scattering principle often measure the particle size of the particle agglomerates. This does not accurately reflect the particle size of the particles in the active cathode material, and even less so the dispersion of the active cathode material in the film layer, since the dispersion of the active cathode material in the film layer increases during the roller pressing process for film formation.The test results obtained by the Malvern laser diffraction method are influenced by the particle size, the specific surface area, and the degree of agglomeration of the active cathode material, and 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, compared to the real dispersion in the electrode foil, so that the particle size obtained by the Malvern laser diffraction method cannot be equivalent or analogous to the particle size obtained by the embodiment of the present application.

[0115] The counting procedure for the area fraction of particles with a particle size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil was performed as follows: The image of the particle determination and identification was imported into the software ImageJ for analysis, and the scale was set according to the scanning electron microscope image. Using the analysis functions "Feret," "Area," "Round," and "Solidity," the particle size, area, sphericity, and roughness of the particles in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil were statistically analyzed. (See the software manual (Image) User Guide IJ 1.)46r) The “Feret” parameter obtained from the analysis represents the maximum distance between all parallel lines in the two-dimensional projection of the particles, which is used to characterize the particle size; and the “Area” parameter obtained from the analysis represents the pixel size of the particles. Since particles with a particle size of less than 50 nm are difficult to identify accurately due to large errors in the statistical process, and since the particle size of the conductive medium is generally less than 50 nm, which can cause large errors in the statistical results, particles with a particle size of less than 50 nm are therefore not counted in the statistical process for particle size of the present application, and the “NaN” corresponding statistical data displayed for Area, Round, or Solidity are deleted.The sum of the area parameters of particles with a particle size greater than or equal to 1 µm and the sum of the area parameters of all particles were calculated as the area of ​​particles with a particle size greater than or equal to 1 µm and the total area of ​​the counted particles, respectively. The sum of the areas of particles with a particle size greater than or equal to 1 µm, divided by the total area of ​​the counted particles, is considered the percentage of the area occupied by particles with a particle size greater than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil.

[0116] In some embodiments, the percentage area fraction of particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is optionally 12%, 12.02%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 34.78%, 34.95%, 35%, 36%, 36.29%, 36.37%, 36.64%, 36.88%, 37%, 38%, 38.09%, 38.44%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 49.96%, 50% or any value in a range between any two of these values.

[0117] In some embodiments, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 3.0%-15.0%.

[0118] In the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm can be tested according to the above test procedure for the percentage area fraction of particles with a particle size of more than or equal to 1 µm.

[0119] In some embodiments, the percentage area fraction of particles with a particle size greater than 50 nm and less than or equal to 200 nm of a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is optionally 3%, 4%, 5%, 5.33%, 5.91%, 6%, 6.35%, 6.42%, 6.49%, 6.52%, 6.54%, 6.55%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 14.81%, 15% or any value in a range between two of these values.

[0120] Theoretical research has shown that, under ideal conditions, spherical particles with a diameter of 314 nm can fill the gaps created by stacking spherical particles with a diameter of 1 µm, thereby increasing the particle size distribution and the packing density of the electrode foil. Particles with a size greater than 50 nm and less than or equal to 200 nm can densely fill the gaps between particles with a size greater than or equal to 1 µm and interact with them to achieve dense stacking.The area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is in a suitable range, which contributes to improving the pressing density of the cathode foil by gradation and at the same time avoids the increase in the internal resistance of the cathode film layer caused by a high area fraction of small particles, so that the battery has a good capacity and further improves the kinetic performance of the battery.

[0121] In some embodiments, the density of the cathode foil when the battery cell is in a fully discharged state is 2.3 g / cm³. 3 -2.6 g / cm² 3 .

[0122] In the present application, a fully discharged state means: storing the battery at 25°C for 2 hours, waiting until the temperature of the battery is maintained at 25°C, and discharging the battery with a constant current of 1 / 3 C to 2.5 V and then discharging the battery with a constant current of 0.1 C to 2.0 V.

[0123] The density of the cathode foil can be tested according to known methods in this technical field.As an example, the battery is placed in an oven environment at 25°C and stored for 2 hours. While the battery temperature is maintained at 25°C, it is discharged to 2.5 V at a constant current of 1 / 3 C and then to 2.0 V at a constant current of 0.1 C. The battery is then disassembled to obtain a cathode foil. The remaining electrolyte solution is treated using the solvent dimethyl carbonate. The electrode foil is dried and cut into a small round disc with area S to obtain mass W1. Using a micrometer, the thickness T1 of the cathode foil is measured. The cathode film layer of the weighed electrode foil is then wiped off. The mass of the collector is weighed and recorded as W2. The thickness T2 of the collector is measured using a micrometer. The compression density PD of the cathode foil is then determined. =(W1-W2) / [(T1-T2)×S].

[0124] In some embodiments, the density of the cathode foil when the battery is in a fully discharged state is optionally 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 , 2.40g / cm³ 3 , 2.41g / cm³ 3 , 2.42g / cm³ 3 , 2.43g / cm³ 3 , 2.44g / cm³ 3 , 2.45g / cm³ 3 , 2.46g / cm³ 3 , 2.47g / cm³ 3 , 2.48g / cm³ 3 , 2.49g / cm³ 3 , 2.50g / cm² 3 , 2.51g / cm³ 3 , 2.52g / cm³ 3 , 2.53g / cm³ 3 , 2.54g / cm³ 3 , 2.55g / cm³ 3 , 2.56g / cm³ 3 , 2.57g / cm³ 3 , 2.58g / cm³ 3 , 2.59g / cm³ 3 , 2.60g / cm² 3 or any value within a range between two of these values.

[0125] In some embodiments, the percentage area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%.

[0126] The area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil lies within the above range, which is beneficial to maintaining the high capacity of the battery and further improves the phenomena of film layer loosening and active substance deposition caused by the tension concentration of large particles during electrode foil compression, in order to improve the cycle performance of the battery.

[0127] In some embodiments, the percentage area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-40%.

[0128] The area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil lies within the above range, which is beneficial to maintaining the high capacity of the battery and further improves the phenomena of film layer loosening and active substance deposition caused by the tension concentration of large particles during the pressing of the electrode foil, in order to further improve the cycle performance of the battery.

[0129] In some embodiments, the uniformity of the particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 0.2%-5%, optionally 0.2%-2%.

[0130] The uniformity of particle distribution of particles with a size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil can be tested using methods known in the technical field. As an example, the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil was divided into three layers of equal thickness along the thickness direction of the electrode foil: a lower layer facing the cathode collector, an upper layer facing away from the cathode collector, and a middle layer located midway between the upper and lower layers. Ten non-overlapping fields of view were selected in each of the upper, middle, and lower layers, and scanning electron micrographs were acquired at a magnification of 10k.The 30 scanning electron microscope images were imported into the software ImageJ for analysis, and 30 values ​​were tested to obtain the percentage area fraction of particles with particle sizes greater than or equal to 1 µm in each of the 30 images. The polar deviation of the 30 obtained values ​​is the distribution uniformity of particles with a particle size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, where the polar deviation is the difference between the maximum and minimum values ​​of the 30 values. In the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the larger particles are distributed more uniformly in the cathode film layer the smaller the distribution uniformity of particles with a particle size greater than or equal to 1 µm.

[0131] In some embodiments, the distribution uniformity of particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is optionally 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%, 1%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 1%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%. 3.6%, 3.7%, 3.8%, 3.9%, 1%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5% or any value in a range between any two of these values.

[0132] The distribution uniformity of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is within a suitable range, and the uniformly distributed large particles can effectively reduce the stress concentration in a local area of ​​the film layer, so that the stress in the pressing process of the film layer is distributed uniformly over the entire area of ​​the film layer, thereby avoiding the phenomenon of local stress concentration caused by particle agglomeration and reducing the probability of the film layer delaminating, thus improving the cycle performance of the battery.

[0133] In some embodiments, in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm, the median L is A50 sphericity 0.6-0.8.

[0134] The test procedure for the sphericity of particles with a particle size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is as follows: Particles with a particle size greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil are identified according to the procedure described above in the present application, and the morphology of the particles in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is analyzed using the "Shape Description" analysis function in ImageJ. According to the software manual (ImageJ User Guide IJ 1.46r), the "Round" parameter obtained from the analysis represents the ratio of the particle's pixel area to the area of ​​a circle with the adjusted longitudinal diameter as its diameter, and can characterize the sphericity of the particles.The closer the particle is to a sphere, the closer the ratio of the pixel area to the area of ​​the circle with the adjusted longitudinal diameter (diameter) is to 1. Therefore, the "Round" parameter obtained from the analysis is used to characterize the sphericity of the particles. Since particles with a size of less than 50 nm are difficult to identify accurately due to large errors in the statistical process, and since the particle size of the conductive medium is generally less than 50 nm, which can cause large errors in the statistical results, particles with a size of less than 50 nm are not counted in the statistical process for particle size in this application, and the corresponding "NaN" statistical data displayed for Round are deleted.To achieve a statistically significant number of samples, at least 10 scanning electron microscope images with non-overlapping fields of view were acquired for each electrode foil. The sphericities of the at least 1000 particles obtained are arranged in order from smallest to largest value, and the cumulative distribution curve of the particle sphericity in the cathode film layer is obtained by taking the sphericity as the horizontal axis and the cumulative area fraction as the vertical axis. L. A50 is a sphericity L-value of the particles if, in the cumulative distribution curve of the sphericity L-value, the cumulative area fraction of the vertical axis is 50%.

[0135] In some embodiments, the median is L A50the sphericity in the cumulative distribution curve of the sphericity area of ​​particles greater than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil optionally 0.60, 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, 0.80 or any value in a range between two of these values.

[0136] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, and the larger particles have better sphericity, which reduces particle bridging due to the irregular shape of the large particles, reduces the void content in the electrode foil and simultaneously reduces the voltage concentration, which is exacerbated by the irregularity of the large particles, which improves the phenomena of film layer loosening and active substance deposition, and the battery cell exhibits high capacity and good cycle performance.

[0137] A person skilled in the art can achieve control of the particle sphericity by any known method. The adjustment of particle sphericity can be achieved, for example, by processes such as comminution, polishing, chemical etching, mechanical mixing, extrusion, coating, granulation, addition of surfactants, etc., as well as by adjusting the parameters of the respective processes.

[0138] In some embodiments, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median L A50 sphericity 0.65-0.75.

[0139] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, which contributes to reducing the stress concentration during the pressing of the electrode foil, which is exacerbated by the irregularity of the large particles, and to improving the phenomenon of film layer loosening and active substance fallout.

[0140] In some embodiments, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median L A50 sphericity 0.67-0.75.

[0141] The median sphericity of particles with a particle size of more than or equal to 1 µm lies within the above range, which helps to further improve the voltage concentration of the large particles during the pressing of the electrode foil, reduce the probability of loosening of the film layer and drop-off of the active substance, and improve the cycle time of the battery cell.

[0142] In some embodiments, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is 5.0%-15.0%.

[0143] The area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is within the above range, the cathode film layer has an appropriate amount of small particles, thus ensuring a sufficient particle fill level, while avoiding the negative effect on the resistance of the film layer caused by an excessively large area fraction of small particles, and the battery improves the kinetic performance of the battery based on a good capacity.

[0144] In some embodiments, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is 5.0%-10.0%.

[0145] The area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is within the above range, the cathode film layer exhibits good particle gradation, the specific resistance of the cathode film layer is further reduced, and the kinetic performance of the battery is further improved on the basis of good capacity.

[0146] In some embodiments, the one-sided thickness of the cathode film layer is 70 µm-120 µm.

[0147] The thickness of the cathode film layer can be tested according to any known method in this technical field. As an example, the thickness of the cathode film layer in the cross-sectional area of ​​the cathode foil was measured along the thickness direction using a scanning electron microscope. Three different locations are randomly selected for measurement and used as the average value for the thickness of the cathode film layer.

[0148] In some embodiments, the one-sided thickness of the cathode film layer is optionally 70 µm, 72.34 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, 83.91 µm, 84 µm, 85 µm, 86 µm, 87 µm, 88 µm, 89 µm, 90 µm, 91 µm, 91.88 µm, 92 µm, 93 µm, 94 µm, 95 µm, 96 µm, 97 µm, 98 µm, 98.93 µm, 99 µm, 100 µm, 101 µm, 102 µm, 103 µm, 104 µm, 105 µm, 105.44 µm, 105.64 µm, 105.65 µm, 105.89 µm, 106 µm, 106.21 µm, 106.34 µm, 107 µm, 108 µm, 109 µm, 110 µm, 111 µm, 112 µm, 113 µm, 114 µm, 115 µm, 116 µm, 116.09 µm, 117 µm, 118 µm, 119 µm, 120 µm or einen beliebigen Wert in einem Bereich zwischen dieser Werte.

[0149] The gram capacity of lithium-containing transition metal phosphate particles is relatively low, and research has shown that it is difficult to meet market demand when the one-sided thickness of the cathode film layer is less than 70 µm. The one-sided thickness of the cathode film layer is within the range mentioned above, which contributes to improving the battery cell's capacity.

[0150] In some embodiments, the one-sided thickness of the cathode film layer is 90 µm-120 µm.

[0151] The thickness of the cathode film layer on one side is within the range above, which contributes to a further improvement in the capacity of the battery cell.

[0152] In some embodiments, the one-sided thickness of the cathode film layer is 100 µm-120 µm.

[0153] Increasing the thickness of the cathode film layer on one side contributes to improving the battery's capacity, and the applicant has found that the cathode film layer is more prone to film loosening and active substance deposition when the thickness of the cathode film layer on one side is greater than or equal to 100 µm. The embodiments of the present application reduce the area fraction of large particles and the density of the cathode film layer, thereby improving the phenomenon of stress concentration of large particles during the pressing of the electrode foil in the stacked electrical core. Simultaneously, an appropriate amount of small particles is added, so that the electrode foil exhibits a further improved density based on a certain content of large particles, and the battery has a better capacity and cycle performance.

[0154] In some embodiments, the cathode film layer further comprises a conductive agent, wherein, with respect to the total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the proportion of the total area of ​​an agglomeration region of the conductive agent is 0.2%-6%, optionally 1.5%-5%.

[0155] Based on the total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the total area of ​​the agglomeration region of the conductive agent lies within the above range, indicating that the conductive agent is uniformly dispersed in the cathode film layer and that it is easy to form a homogeneous conductive network, which helps to reduce local polarization or even lithium precipitation of the battery during the cycling process.

[0156] Simultaneously, the corresponding quantity of small particles in the present application can be used as a basic conductive skeleton to fill the gap left by the large particles, while the dispersed agglomerates of the conductive agent are used as nodes for long-range conduction to form a graded conductive structure; due to the lithium-containing transition metal phosphate particles in the large particles being easily rebounded, the agglomeration area of ​​the conductive agent in the above area can also be able to inhibit the rebound of the large particles by means of the uniform distribution of the conductive agent to form a mechanical bond between the particles and even the film layer, improving the cohesion of the film layer, reducing powder fallout from the film layer, reducing the phenomenon of active substance deposition, and improving the battery lifetime.

[0157] The area fraction of the conductive agglomeration region, relative to the total cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, can be determined using the following procedure. The area of ​​the conductive agglomeration region in this scanning electron microscope image is measured at a magnification of 3k by scanning the cross-sectional area of ​​the cathode film layer using a similar procedure described above. Since the conductive material is generally carbon-based, such as conductive carbon black, carbon nanotubes, etc., the conductive agglomeration region tends to appear as a black agglomeration compared to other areas in the cathode film layer, and the agglomerated conductive material is visible at high magnification.The conductive agglomeration area is the region of black areas where the conductive material is clearly aggregated in the scanning electron micrograph. Using image analysis software such as ImageJ to count the white-marked areas in the image, the regions where Feret is greater than or equal to 2 µm are filtered out, and the sum of the areas of these regions is the total area of ​​the conductive agglomeration area in the scanning electron micrograph. The area fraction of the conductive agglomeration area was characterized by dividing the total area of ​​the conductive agglomeration area in the scanning electron micrograph at a magnification of 3k by the area of ​​the scanning electron micrograph.Three scanning electron microscope images with non-overlapping areas are taken at random and averaged as "the proportion of the total area of ​​the agglomeration area of ​​the conductive medium relative to the total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil".

[0158] In some embodiments, the conductive means comprises carbon nanotubes, wherein the carbon nanotubes comprise one or more of single-walled carbon nanotubes, thin-walled carbon nanotubes, multi-walled carbon nanotubes, wherein the conductive means further optionally comprises conductive carbon black.

[0159] Carbon nanotubes have a high length-to-diameter ratio, which, due to their unique fiber structure, bridges particles of different sizes in the thickness direction, forming a long-distance conductive path and simultaneously improving the binding force between the particles, reducing local polarization and even lithium precipitation during the battery cycle and improving the battery's lifespan; furthermore, the rebound phenomenon of large particles in the cathode film layer is reduced by the binding effect, thereby decreasing the phenomenon of active substance deposition in the film layer.

[0160] Due to its nanoscale dimensions, the conductive carbon black is densely coated on the surface of the active cathode material particles, forming high-density, point-like conductive contacts. The combination of carbon nanotubes and carbon black further enhances the conductive network in the cathode film layer by addressing both long-range and short-range conductivity.The high specific surface area of ​​the conductive carbon black significantly improves the adsorption capacity of the electrolyte solution, thereby reducing electrolyte solution consumption during the cycle; the mechanical toughness of the carbon nanotubes can buffer the expansion stress of the electrode foil; the synergistic effect of the two can reduce the phenomenon of electrolyte solution extrusion due to the sharp increase in the expansion force of the electrode foil during long cycles and improve the battery's lifespan.

[0161] In some embodiments, the agglomeration area of ​​the conductive agent comprises carbon nanotubes and conductive carbon black.

[0162] The researchers found that carbon nanotubes, due to their high surface energy, tend to agglomerate, leading to an uneven distribution in the cathode film layer and preventing the formation of an effective network structure. Conductive carbon black, with a surface energy close to that of carbon nanotubes, can be adsorbed onto their surface to form a physical barrier. This increases resistance to agglomeration, reduces direct contact between the nanotubes, and thus inhibits agglomeration, thereby improving the uniformity of carbon nanotube distribution within the cathode film layer.On the one hand, this helps to improve the electrical conductivity of the cathode film layer and the kinetic performance of the battery; on the other hand, it helps to exert the binding effect of the carbon nanotubes on the cathode film layer, reducing the risk of cathode film delamination and further improving the kinetic performance and lifetime of the battery. Furthermore, the agglomeration of carbon nanotubes in the agglomeration region of the conductive medium also blocks the local ion transfer pathway in this region, and the collocation of conductive carbon black can improve the lithium-ion transfer capacity in this region, reduce local polarization, and further improve the cycle stability of the battery.

[0163] In some embodiments, the mass fraction C1 of the carbon nanotubes fulfills 0 with respect to the mass of the cathode film layer. <C1<2,5% und der Massengehalt C2 des leitfähigen Rußes 0<C1≤2,5%.

[0164] In some embodiments, the mass fraction C1 of the carbon nanotubes, based on the mass of the cathode film layer, is optionally 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 any value in a range between two of these values.

[0165] In some embodiments, the mass fraction C2 of the conductive carbon black, based on the mass of the cathode film layer, is optionally 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 any value in a range between two of these values.

[0166] The mass content of carbon nanotubes and conductive carbon black within the above range can effectively reduce the agglomeration phenomenon of carbon nanotubes and form a good conductive network structure, thereby effectively reducing the voltage concentration of the cathode film layer and improving the retention rate of electrolyte solution of the cathode film layer during long cycles, thereby further reducing the risk of electrode foil film layer delamination and the degree of polarization, increasing the kinetic performance of the battery and improving the cycle life of the battery.

[0167] In some embodiments, the cathode film layer further comprises a dispersing agent, wherein the dispersing agent comprises hydrogenated nitrile butadiene rubber HNBR.

[0168] The polar groups (e.g., cyano group, -CN) in the HNBR hydrogenated nitrile butadiene rubber molecule can interact with the hydroxyl group (-OH) or the metal oxide sites on the surface of the lithium-containing transition metal phosphate particles (e.g., hydrogen bonding, dipole effect) to improve particle compatibility with the solvent and reduce interfacial tension between the particles and the solvent. This improvement in interfacial tension is even more pronounced for large particles. In this way, the large and small particles can be dispersed more easily and uniformly in the film layer, thereby reducing particle aggregation due to hydrophobicity, improving the dispersion of large particles in the cathode film layer, and lowering the concentration of stresses generated during film stamping.

[0169] When the slurry is dried to form a film, the elastic network structure of HNBR can buffer the shrinkage stress caused by solvent evaporation, rearrange the conductive agent during the process due to capillary action, and reduce the area fraction of the conductive agent's agglomeration zone. The uniform distribution of the conductive agent is beneficial for inhibiting the rebound of large particles, forming mechanical constraints on the particles and even the film layer, improving film layer cohesion, reducing powder shedding from the film layer, minimizing active substance deposition, and extending battery life.

[0170] In some embodiments, the mass content of the dispersant is 0.5%-2%, based on the mass of the cathode film layer.

[0171] In some embodiments, the mass fraction of the dispersing agent, based on the total mass of the cathode film layer, is optionally 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% or any value in a range between two of these values.

[0172] The mass fraction of the dispersant is within the above range, which allows for a uniform dispersion of the particles in the cathode film layer, while maintaining a high charge capacity in the cathode film layer, and ensuring that the battery has good capacity and cycle performance.

[0173] In some embodiments, the cathode film layer is provided with a lower coating layer at a lower region facing the cathode collector, the lower coating layer comprising a conductive agent and a binder, wherein the conductive agent comprises carbon nanotubes and conductive carbon black, and the binder comprises a vinylidene fluoride polymer.

[0174] In some embodiments, the thickness of the lower coating layer is 0.5 µm-5 µm.

[0175] In some embodiments, the thickness of the lower coating layer is 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 any value in a range between two of these values.

[0176] The lower coating layer provided in the embodiments of the present application contributes to improving the adhesion between the cathode film layer and the cathode collector and to reducing the phenomenon of voltage concentration at the large particles, thereby decreasing the probability of cathode film layer delamination and improving the cycle stability of the battery. At the same time, compared to direct contact between the cathode collector and the cathode film layer, the contact area between the lower coating layer and the cathode film layer is increased, which contributes to increasing the electron transfer area between the collector and the cathode film layer, thereby reducing the internal resistance of the electrode foil and improving the kinetic performance of the battery.

[0177] In some embodiments, the median is C 50of the degree of graphitization in the cumulative distribution curve for a graphitization C value of the cathode film layer obtained in an area scanning mode of the laser microconfocal Raman spectrometer, is greater than 0.95 and less than or equal to 1.20; where the graphitization C value I G / I D is, where I G for the intensity of the G-peak of the Raman spectrum at 1580±100cm -1 and I D for the intensity of the D-peak of the Raman spectrum at 1350±100cm -1 stands.

[0178] In the present application, the graphitization C-value can be obtained by an area-scanning mode of the laser microconfocal Raman spectrometer. As an example, a laser microconfocal Raman spectrometer (a high-precision Renishaw laser microconfocal Raman spectrometer) is used, an excitation wavelength of 532 nm is selected, and a suitable amount of the cathode film layer is taken for area scanning of the surface or a cross-sectional area along the thickness direction of the electrode foil. The scanning area is 45 µm × 45 µm, subdivided into 10 × 10 grids, with the vertex of the grid serving as the test point. The step size is 5 µm, and the total number of scan points is 100 to obtain the C-values ​​at various locations and the cumulative distribution curve of the C-values ​​in the area-scanning area.

[0179] The cathode film layer in the present application can be either a freshly produced cathode film layer or a cathode film layer obtained by dismantling a battery. The surface of the cathode film layer obtained by dismantling the battery inevitably contains residues of electrolyte salt particles, and to improve the accuracy of the test, an area scan of a cross-sectional area of ​​the cathode film layer is preferably performed along the thickness direction of the electrode foil to characterize the degree of graphitization of the cathode film layer.

[0180] The graphitization degree C value of the cathode film layer is obtained from the peak intensity ratio of the G-peak (G-band) and the D-peak (D-band) of the Raman spectra, with the position of the G-peak at 1580±100cm -1 lies and the sp 2-Hybrid structure of carbon is characterized, and the position of the D-peak is at 1350±100cm -1 lies and characterizes the disordered structure, where the disorder of carbon means that there is no regular arrangement between the carbon atoms in the structure.

[0181] The cumulative distribution curve of graphitization degree-C value is the curve obtained when at least 100 C values ​​are arranged in order from smallest to largest, using the graphitization degree as the horizontal axis and the cumulative number of values ​​as the vertical axis. 50 The C-value is determined when the cumulative number fraction on the vertical axis of the curve of the cumulative distribution of graphitization degree-C-value is 50%. The median C 50The degree of graphitization, compared to a point value, can reflect the degree of graphitization of the particles in the cathode film layer, i.e., the degree of ease of particle sliding; and compared to a mean value, it can reduce the influence of extreme values ​​in the test process and improve the reliability of the test results.

[0182] A person skilled in the art can regulate the degree of graphitization of the active material particles using any known method. For example, the degree of graphitization of the active material particles can be adjusted by regulating the carbon source, the sintering temperature, the sintering time, the sintering pressure, and the sintering atmosphere.

[0183] In some embodiments, the median is C 50of the graphitization degree in the cumulative distribution curve for the graphitization C value of the cathode film layer optionally 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20 or any value in a range between two of these values.

[0184] In the cumulative distribution curve of the graphitization C-value of the cathode film layer, obtained in an area-scanning mode of the laser microconfocal Raman spectrometer, the median C50 of the graphitization degree lies within the range mentioned above. Therefore, the electrode foil density can be further improved by particle slippage without unduly affecting the proportion of large and small particles in the cathode film layer. This keeps the area fraction of large and small particles within a suitable range, reducing the probability of cathode film layer delamination and preventing excessive resistance. This, in turn, improves the battery's cycle life and kinetic performance while maintaining battery capacity.

[0185] In some embodiments, the lithium-containing transition metal phosphate particles in the cathode film layer comprise a component with the formula shown below: 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, and where 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, 0≤q≤0.1.

[0186] In some embodiments, m is optionally 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 any value in a range between any two of these values; x is optionally 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0 or any value in a range between any two of these values; y is optionally 0.95, 0.96, 0.97, 0.98, 0.99, 1.00 or any value in a range between any two of these values; j is optionally 3.5, 3.6, 3.7, 3.8, 3.9, 4 or any value in a range between any two of these values; q is optionally 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or any value in a range between any two of these values.

[0187] In some embodiments, the lithium-containing transition metal phosphate particles comprise titanium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of titanium is 500 ppm-8000 ppm, optionally 1000 ppm-3000 ppm.

[0188] In some embodiments, the titanium elements are evenly distributed in the lithium-containing transition metal phosphate particles.

[0189] Both the type and the content of the elements in the lithium-containing transition metal phosphate particles in the cathode film layer can be tested according to any known methods in the relevant technical field. For example, the titanium content is tested using inductively coupled plasma emission spectrometry with reference to Annex C of GB / T 33822-2017.

[0190] When titanium is doped into the lithium-containing transition metal phosphate particles, the resulting Ti-OP bond exhibits a strong bonding interaction that reduces the contraction / expansion amplitude of the lattice by anchoring the phosphate group when lithium ions are unembedded, thereby suppressing the structural stress induced by the phase transition and contributing to improved battery cycle life; furthermore, the Ti-OP bond can form a more stable channel for lithium ion diffusion, thereby lowering migration barriers and contributing to improved battery kinetic performance.

[0191] The mass content of titanium within the above range contributes to improving the lithium ion transfer rate of the active cathode material, reduces the risk of lithium precipitation, and improves the kinetic performance of the battery.

[0192] In some embodiments, the mass fraction of titanium, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, is optionally 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm or any value in a range between two of these values.

[0193] In some embodiments, the lithium-containing transition metal phosphate particles comprise vanadium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of vanadium is 500 ppm-5000 ppm, optionally 500 ppm-3000 ppm.

[0194] In some embodiments, the vanadium elements are evenly distributed in the lithium-containing transition metal phosphate particles.

[0195] When vanadium is doped in lithium-containing transition metal phosphate particles, it exhibits multivalent properties. When +5-valent vanadium (V) 5+ When doped with phosphorus sites, its larger radius leads to lattice distortions, enlarges the lithium-ion diffusion channels, and improves the ionic conductivity of the active cathode material; when +3-valent vanadium (V 3+ ) is doped with transition metal sites, the charge is compensated by lithium gaps or interstitial oxygen, creating defect energy levels and improving the electronic conductivity of the active cathode material.

[0196] The mass content of vanadium within the above range contributes to improving the lithium ion transfer rate of the active cathode material, improving the electron conductivity of the active cathode material, and further improving the kinetic performance of the battery through the synergistic effect with doping with titanium.

[0197] In some embodiments, the mass content of vanadium, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, is optionally 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm or any value in a range between two of these values.

[0198] In some embodiments, the lithium-containing transition metal phosphate particles in the cathode film layer comprise one or more of the following materials: lithium iron phosphate, lithium manganese phosphate, lithium fluoro-substituted vanadium phosphate, lithium ferromanganese phosphate and their modified materials.

[0199] In some embodiments, the lithium-containing transition metal phosphate particles in the cathode film layer comprise one or more of the following materials: lithium iron phosphate and its doped modified materials, as well as modified coating materials.

[0200] In some embodiments, the porosity of the cathode film layer is 14%-28%.

[0201] The porosity of the cathode film layer can be tested using the following procedure. Import the scanning electron microscope image of the cathode film layer cross-section obtained using the above method into the ImageJ software, select the straight line tool, use a straight line to mark the length of the scale in the image, click "Analyze Set Scale" and adjust the scale parameters in the software according to the length of the scale in the image.Select the rectangle tool, select the portion of the image outside the scale range, use "Image Duplicate" to duplicate the selected area, use "Image Type 8 bit" to adjust the image format; select "Analyze Set Measurements" and select the following five options: "Area", "Mean gray value", "Area Fraction", "Limit to threshold", "Feret's diameter", selecting 3 for "Decimal places", and successively selecting "Image" - "Adjust" - "Threshold", and successively setting the "Threshold" position to 0 and 100, thereby enabling the "Analyze-Measure" function to export the pore data in the scanning electron microscope image of the section surface.Use “Image” - “Overlay” - “Flatten” to export and obtain the pore image; click “Apply” in “Threshold”, then click “Analyze” - “Analyze Particles”, checking the four columns on the left to obtain the pore statistics.

[0202] It is understood that, in an embodiment of the present application, the "pores" in the cross-sectional area of ​​the cathode film layer are identified by the color difference and the threshold of the image. The "pore" is not the porosity data obtained in the exhaust gas test, but is primarily used to characterize the cross-sectional area between the particles in the cross-sectional area of ​​the cathode film layer. This method is superior to the exhaust gas method because the porosity obtained by the exhaust gas method is related to the pores between the particles and also to the pores in the carbon material on the surface of the lithium iron phosphate particles, and therefore the pores between the particles cannot be objectively represented.

[0203] The porosity of the cathode film layer lies within the above range, which means that the cathode film layer has a better gradation of large and small particles, and it is conducive to improving the properties of the liquid retention of the electrolyte solution, improving the ion diffusion capability of the cathode film layer with a certain area fraction of large particles, and improving the kinetic performance of the battery.

[0204] In some embodiments, the porosity of the cathode film layer is optionally 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28% or any value in a range between two of these values.

[0205] In some embodiments, the specific resistance of the cathode film layer is 10 Ω·cm to 35 Ω·cm.

[0206] A resistance meter (Suzhou Lidian) is used to perform the test under a standard pressure condition of 25 MPa, and during the test 8 test points are randomly selected on the film layer of the cathode foil, and the pressure is held for 15 s at each test point to obtain the specific resistance of that test point location; the average value of the 8 specific resistances is taken as the specific resistance of the cathode film layer.

[0207] In some embodiments, the resistivity of the cathode film layer is optionally 10 Ω cm, 11 Ω cm, 12 Ω cm, 13 Ω cm, 14 Ω cm, 15 Ω cm, 16 Ω cm, 17 Ω cm, 18 Ω cm, 19 Ω cm, 20 Ω cm, 21 Ω cm, 22 Ω cm, 23 Ω cm, 24 Ω cm, 25 Ω cm, 26 Ω cm, 27 Ω cm, 28 Ω cm, 29 Ω cm, 29.72 Ω cm, 29.88 Ω cm, 30 Ω cm, 30.55 Ω·cm, 30.73 Ω·cm, 31 Ω·cm, 31.5 Ω·cm, 32 Ω·cm, 32.2 Ω·cm, 33 Ω·cm, 33.67 Ω·cm, 34 Ω·cm, 34.98 Ω·cm, 35 Ω·cm or any value in a range between any two of these values.

[0208] The specific resistance of the cathode film layer is in a suitable range, which contributes to reducing the impedance of electron transfer, reducing charge / discharge polarization, and improving the kinetic performance of the battery.

[0209] In some embodiments, such as in Fig. As shown in Figure 1, the battery cell further comprises a separator 20 arranged between the cathode foil and the anode foil, the separator 20 comprising a base film 201 and a ceramic layer 202 provided on both sides of the base film 201, and a binder layer 203 provided on at least one of the sides of the ceramic layer 202 facing away from the base film 201, the binder layer 203 being a continuous layer with a porous structure, the binder layer 203 comprising a vinylidene fluoride polymer.

[0210] In some embodiments, the vinylidene fluoride polymer comprises a homopolymer of vinylidene fluoride (PVDF) and copolymers of vinylidene fluoride with other monomers, e.g., a copolymer of vinylidene fluoride and hexafluoropropylene.

[0211] As in Fig. As shown in Figure 2, aqueous PVDF is often used for the separator bonding layer according to the prior art, which tends to form an island-like structure in the separator, which on the one hand helps to create a gap for the expansion of the electrical core, and on the other hand is easy to produce; however, such a separator bonding layer has a small bonding area and a weak bonding force.

[0212] As in Fig.Figure 3 shows a schematic representation of the surface morphology of the binder layer 203 of the separator of the embodiments of the present application. The binder layer of the separator of the embodiments of the present application has a certain porous structure in its continuous structure, and the ceramic layer between the base film and the binder layer can be observed through the porous structure.It is understood that if the continuous layer with the porous structure is used as a bonding layer, it may become block-shaped due to contact with the cathode foil or the anode foil, or extrusion by force during the manufacturing or cycling process of the electrode foil. The continuous layer referred to in the present application does not require that the bonding layer be continuous throughout the entire battery; rather, it refers to the continuous layer with a uniform porous structure at the microscopic layer level, e.g., a continuous layer with a uniform porous structure when viewed under a microscope, instead of an island-like structure.To obtain feedback on the actual morphology of the separator, sampling preferably takes place in an area of ​​the battery where there is only a weak bond between the separator's bonding layer and the cathode or anode foil. This can be achieved, for example, by sampling the separator at a point where the projection extends beyond the cathode and anode foils, or by sampling the separator near the surface of the electrode assembly. A separator sampled in this way better reflects its actual condition.

[0213] The separator provided by the embodiments of the present application uses a continuous layer with a porous structure as a bonding layer, which has a larger bonding area than the island-shaped bonding layer in the prior art, thereby making the bond between the separator and the cathode film layer stronger and more uniform, and at the same time, by means of a pore structure in the bonding layer, it can combine both the lithium-ion transfer efficiency and the kinetic performance of the battery.Simultaneously, the compression force between the electrode foils of the stacked electric core is low compared to the wound electric core during the manufacturing process. Furthermore, the lithium-containing transition metal phosphate particles with a particle size of 1 µm or greater reduce the compactness of the internal components of the electric core during the rebound process, improve the impedance of the electric core, and increase the likelihood of the film layer precipitating into powder or even detaching. The separator provided by the embodiments of the present application uses a continuous layer with a porous structure as a bonding layer, which is particularly suitable for the stacked electric core, improves the rebound phenomenon of the stacked electric core during long cycles, and enhances the retention of battery capacity during long cycles.Furthermore, when the outer electrode foil is pulled and the electrode tab is welded, a relative displacement of the stacked electrical core occurs between the electrode foil and the separator, causing the film layer to tend to fall off powder and even the cathode and anode to overlap, creating the risk of an internal short circuit.

[0214] The embodiments of the present application use the continuous layer with the porous structure as a bonding layer to improve the bonding strength between the separator and the electrode foil while maintaining the permeability and porosity of the separator, to improve the stability of the electrode foil, to further reduce the risk of powder falling due to the relative displacement of the electrode foil and the separator or even the occurrence of an internal short circuit, and to improve the cycle stability of the battery.

[0215] In some embodiments, such as in Fig. As shown in Figure 4, the battery cell 5 comprises a housing 50, wherein the stacked electrical core is contained in the housing 50, wherein the housing 50 has a dimension of L0 in a longitudinal direction (X-direction), wherein the housing has a dimension of W0 in a width direction (Y-direction), wherein the housing has a dimension of H0 in a thickness direction (Z-direction), wherein 450 mm ≤ L0 ≤ 1300 mm, 100 mm ≤ W0 ≤ 150 mm, and 14 mm ≤ H0 ≤ 22 mm.

[0216] The dimensions of the housing of the battery cell of the embodiments of the present application are within the above range, which contributes to achieving a better battery capacity.

[0217] In some embodiments, L0 is optionally 450 mm, 460 mm, 470 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 mm, 1300 mm or any value in a range between any two of these values.

[0218] In some embodiments, W0 is optionally 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm or any value in a range between any two of these values.

[0219] In some embodiments, H0 is 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm or any value in a range between any two of these values.

[0220] In some embodiments, the dimension L0 of the housing in the longitudinal direction satisfies the following condition: 450 mm ≤ L0 ≤ 650 mm.

[0221] If the length dimension L0 of the casing is 450 mm ≤ L0 ≤ 650 mm, the battery cell has a shorter length, which contributes to shortening the electron transfer path and reducing the internal resistance of the battery, while simultaneously reducing the infiltration distance of the electrolyte solution in the pores of the electrodes, improving the uniformity of the infiltration and increasing the kinetic power of the battery; in particular under fast charging conditions, it can reduce the phenomenon of uneven temperature rise and current density in the length direction of the electrode foil.

[0222] In some embodiments, the dimension L0 of the housing in the longitudinal direction satisfies the following condition: 900 mm ≤ L0 < 1300 mm.

[0223] The longitudinal dimension L0 of the housing meets the following condition: 900 mm ≤ L0 ≤ 1300 mm. A significant increase in the battery cell dimensions can effectively simplify the traditional module structure, allowing the battery cell to be directly integrated into the battery pack. Battery mounting is achieved via structural components at the end section of the large surface area, which significantly improves space utilization and thus increases the overall capacity of the battery system for the same volume. Simultaneously, this reduces the number of structural components and improves the battery's energy density, further enhancing its capacity.

[0224] In some embodiments, such as in Fig.As shown in Figure 4, the material of the housing 50 is a soft packaging material, wherein the soft packaging material comprises an aluminum-plastic composite film, optionally a composite film formed from one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), polyethylene (PE) with aluminum.

[0225] The soft packaging material has high elongation, and its casing is thin and soft, which contributes to better space utilization of the battery system and thus increases the energy density of the battery system; however, the soft packaging material, such as aluminum-plastic composite foils, has poor thermal conductivity, which leads to low heat dissipation efficiency of the soft-pack battery. Therefore, if the surface area fraction of the small particles in the cathode film layer is too large, the specific resistance of the cathode film layer increases, leading to excessive heat production in the battery during the cycling process and further exacerbating the problem of poor heat dissipation in the soft-pack battery.By using the soft packaging material as the casing and controlling the area fraction of the small particles in the cathode film layer within a suitable range, the battery of the embodiments of the present application has a high capacity and good cycle performance.

[0226] In some embodiments, such as in Fig. As shown in Figure 4, the housing 50 comprises a first sealing zone 51, wherein the first sealing zone 51 is provided at at least one end of the stacked electrical core extending in the width direction (Y-direction); wherein the first sealing zone 51 comprises a folded edge structure extending in the length direction (X-direction), wherein the folded edge structure is provided with an encapsulating adhesive, wherein the encapsulating adhesive is provided successively along the length direction (X-direction) and secures the folded edge structure;

[0227] The folded edge structure is a reinforcement structure formed by an unlimited number of folds of the sealing zone, e.g. a single folded edge structure that is folded once, or a double folded edge structure that is folded on both sides.

[0228] The SEI film thickens during the electrode foil's cycling process, leading to strong rebound and gas production during long cycles. The sealing zone of the soft-packed electrical core serves to seal the electrode assembly, but this zone has limited strength and is easily washed away by the strong rebound and high gas production within the film layer.

[0229] The embodiments of the present application further improve the sealing strength of the first sealing zone by incorporating a folded edge structure extending along the longitudinal direction within the first sealing zone. The encapsulation adhesive is continuously applied along the longitudinal direction and secures the folded edge structure, in contrast to discontinuous application of the encapsulation adhesive along the longitudinal direction. This further improves the encapsulation strength, achieves continuous reinforcement of the sealing zone in the longitudinal direction, and reduces the likelihood of the electrode foil popping out of the sealing zone of the packaging during the cycle process.

[0230] In some embodiments, the housing 50 comprises at least one second sealing zone 52, wherein the second sealing zone 52 is provided at at least one end of the stacked electrical core along the longitudinal direction of the housing, wherein the second sealing zone 52 is provided on one side of the electrode tab of the stacked electrical core.

[0231] It goes without saying that the cathode tab and the anode tab can be located on the same side of the stacked electrical core, as shown in Fig. 4 shown, or that they may be provided on opposite sides of the stacked electrical core.

[0232] In some embodiments, the battery cell 5 further comprises a lead element 53 which is connected to the electrode tabs of the battery cell; for example, the lead element 53 may be welded to the electrode tabs, wherein the lead element 53 is a conductive element; at least a part of the lead element 53 is located outside the housing 50; the lead element 53 acts as an electrode lead end of the battery cell 5; the lead element 53 is used to facilitate the electrical connection of the battery cell 5 to other battery cells 5 or other components. The lead element 53 may, for example, have the form of a sheet.

[0233] Accordingly, the supply element 53 also includes a cathode supply element and an anode supply element, wherein the cathode supply element is connected to the cathode tab and the anode supply element is connected to the anode tab.

[0234] The second sealing zone is located on the side of the electrode tab; the electrode tab must be connected to a lead element, and the connection strength of the lead element and the housing material is relatively weak, so that the gas can easily be flushed out of the second sealing zone, which contributes to achieving a directed pressure relief of the battery, reducing the effects of thermal runaway on the adjacent electrical core, and improving the overall lifespan of the battery.

[0235] In some embodiments, a plurality of adhesive rings circumferentially in the width direction are provided around an outer circumference of the stacked electrical core, wherein the adhesive rings circumferentially in the width direction are provided at intervals along the length direction.

[0236] The spaced arrangement of the adhesive rings in the longitudinal direction, which surround the electrical core along the width direction, is beneficial for fixing the position between the electrode foils in the electrical core and reducing the probability of displacement of the electrical core when the battery is shaken. This is particularly suitable for long batteries, which can effectively reduce displacement between the electrode foils in the longitudinal direction and lead to the phenomenon of lithium precipitation. It is also beneficial for keeping the internal spatial structure of the battery stable, so that it does not affect the normal operation of the battery.

[0237] In some embodiments, the battery cell capacity at 25°C is 100 Ah-300 Ah, optionally 110 Ah-190 Ah, and further optionally 125 Ah-180 Ah.

[0238] In the present application, the capacity of the battery cell has a meaning known in the art and can be tested by methods known in the art. For example, the battery is charged at 25 °C with a charging rate of 0.5C of the nominal capacity of the battery cell to 3.65 V, then charged with a constant voltage of 3.65 V to 0.05 C and left to stand for 10 minutes, then discharged with a discharge rate of 1C to 2.5 V and left to stand for 10 minutes, and the capacity C in units of Ah is calculated during the discharge process according to the formula C=I*t.

[0239] In some embodiments, the capacity of the battery cell at 25°C can optionally be 100Ah, 125Ah, 130Ah, 135Ah, 140Ah, 145Ah, 150Ah, 155Ah, 160Ah, 165Ah, 170Ah, 175Ah, 180Ah, 185Ah, 190Ah, 300Ah or any value in a range between two of these values.

[0240] In the battery cell of the embodiments of the present application, a suitable housing dimension is set to accommodate the stacked electrical core, and an appropriate proportion of large particles in the film layer of the electrode foil in the stacked electrical core is controlled so that the battery cell has a high capacity.

[0241] In some embodiments, the cathode collector can be a metal foil or a composite collector. For example, an aluminum foil can be used as the metal foil. The composite collector can comprise a base layer of polymeric material and a metal layer formed on at least one surface of the polymeric base layer. The composite collector can be formed by depositing metallic material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0242] In some embodiments, the anode collector can be a metal foil or a composite collector. For example, a copper foil can be used as the metal foil. The composite collector can comprise a base layer of polymeric material and a metal layer formed on at least one surface of the polymeric base layer. The composite collector can be formed by depositing metallic material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as a substrate made of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0243] In some embodiments, the anode film layer comprises an active anode material. The active anode material may, for example, comprise at least one of the following materials: synthetic graphite, natural graphite, soft carbon, or hard carbon. However, the present application is not limited to these materials, and other conventional materials suitable for use as active anode materials in batteries may also be used. It is possible to use only one of these active anode materials or to use more than two in combination.

[0244] In some embodiments, the anode film layer optionally comprises a binder. This binder may be at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0245] In some embodiments, the anode film layer optionally includes further additives, such as thickening agents (e.g. sodium carboxymethylcellulose (CMC-Na)), etc.

[0246] In some embodiments, the anode foil can be produced as follows: Dispersing the components described above for the production of the anode foil, such as the active anode material, the conductive agent, the binder and other components, in a solvent (e.g. deionized water) to form an anode slurry; applying the anode slurry to the anode collector and obtaining the anode foil after drying, cold pressing and other processes.

[0247] A second aspect of the present application provides a battery device comprising a battery cell according to the first aspect of the present application.

[0248] The battery devices disclosed in the embodiments of this application can be used in power-consuming devices that use the battery devices as a power source, or in various energy storage systems that use the battery devices as an energy storage element. The battery devices can be used, among other things, for mobile phones, tablets, laptops, electric toys, power tools, electric bicycles, electric vehicles, ships, spacecraft, and the like, as well as for vehicles. Electric toys can include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric boat toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0249] Furthermore, the present application provides a power-consuming device that uses the battery device as a power source, wherein the power-consuming device comprises at least one of the battery cells of the present application, a battery module, and a battery pack. 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.

[0250] Depending on requirements, the power-consuming device can be a battery cell, a battery module or a battery pack.

[0251] Fig.Figure 5 shows an example of the power-consuming device. The power-consuming device disclosed in the embodiments of the present application can be a fuel oil vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, a supercharged vehicle, and the like. The vehicle is provided internally with a battery device. The battery device can be located on the underside, at the front, or at the rear of the vehicle. The battery device can be used to supply power to the vehicle; for example, the battery device can be used as an operating power source for the vehicle. The vehicle can further comprise a control unit and a motor, the control unit serving to control the battery device in order to supply power to the motor, for example, to meet the vehicle's operating energy requirements for starting, navigating, and driving.In some embodiments of the present application, the battery device can be used not only as an operating energy source for the vehicle, but also as a propulsion energy source for the vehicle, instead of or partially instead of heating oil or natural gas to provide propulsion energy for the vehicle.

[0252] The embodiments of the present application also provide an energy storage device which uses a battery device as a power source, wherein 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. Example of implementation

[0253] The following describes exemplary embodiments of the present application. The embodiments described below are exemplary, serve to explain the present application, and cannot be construed as limiting the present application. Unless specific techniques or conditions are indicated in the exemplary embodiments, they correspond to the techniques or conditions described in the relevant literature or to the information in the product specification. The reagents or instruments used without manufacturer identification are all commercially available products. Exemplary embodiment 1.(1) Production of the active cathode material

[0254] Lithium carbonate, iron phosphate, titanium dioxide, vanadium pentoxide, sucrose, glucose, and polyethylene glycol are added to deionized water and mixed in a premixing vessel, the lithium carbonate and iron phosphate being dosed so 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%, and after uniform mixing, a mixed raw material with a solids content of 38% is obtained;

[0255] In this case, the particle size Dv is 50 of lithium carbonate 6 µm; the morphology of the iron phosphate particles is spherical; titanium dioxide and vanadium pentoxide are nanoparticles; the purity of sucrose is ≥98%; the moisture content of dextrose is <0.5%; and the weight mean molecular weight of polyethylene glycol is 1500.

[0256] The mixed raw material was milled twice in a sand mill, with one hour of coarse milling followed by one hour of fine milling, and the temperature of the slurry was controlled to less than 40°C during the milling process to obtain the mixed slurry; the particle size Dv50 of the solid particles in the mixed slurry is 0.40 µm, and spray drying was carried out to obtain a dry precursor powder whose particle size Dv50 after drying is 55.50 µm.

[0257] The precursor powder was sintered in two stages at elevated temperature in a nitrogen atmosphere to obtain the active cathode material: The temperature was increased from 25°C to 460°C at a heating rate of 2°C / min (first heating stage) and held for 3 hours. The temperature was then increased from 460°C to 780°C at a heating rate of 5°C / min (second heating stage) and held for 12 hours. During the heating stage, the ventilation was greater than during the constant temperature stage (ratio 1.5:1), with a total ventilation volume of 1350 cm³. 3 / h, followed by cooling; The active cathode material of lithium iron phosphate with a carbon material on the surface of the lithium iron phosphate with a particle size Dv50 of 1.6 µm is obtained by airflow comminution, wherein, based on the total mass of the active cathode material, the mass content of Ti element is 1050 ppm and the mass content of V element is 950 ppm.

[0258] The above Dv10, Dv50 and Dv90 refer to data obtained through the Malvern laser scattering test. (2) Production of the cathode foil:

[0259] The above active cathode material, comprising 93.9% by mass, the conductive agent, comprising 2% by mass, and the binder polyvinylidene fluoride, comprising 3% by mass, are mixed in the solvent N-methylpyrrolidone. The dispersing agent HNBR, comprising 1.1% by mass, is then added, and the mixture is sufficiently mixed, stirred, and dispersed in a mixing vessel to produce the cathode slurry. After completion of the stirring process, the cathode slurry is transferred to a coating process, where the mass fraction of the active cathode material, the conductive agent, the binder, and the dispersing agent is calculated based on the total mass of solids in the cathode slurry. The conductive medium comprises conductive carbon black with a mass fraction of 1.33% and single-walled carbon nanotubes with a mass fraction of 0.67%, the conductive carbon black having a specific surface area of ​​85 m². 2 / g and has an oil absorption value of 200 ml / 100 g and the single-walled carbon nanotubes have an average length of 30 µm, a specific surface area of ​​300 m² 2 / g and have a mass content of metallic impurities in the single-walled carbon nanotubes of <1 wt.%;

[0260] The cathode slurry is transferred to an aluminum foil of the collector for drying and coating, and after hot pressing a cathode foil with a one-sided thickness of the cathode film layer of 105.64 µm and a pressing density of 2.36 g / cm³ is produced. 3 obtained. The speed for the coating transfer is 20 m / min.

[0261] The hot pressing process comprises at least three hot rolling presses, wherein the hot rolling pressure increases sequentially and is successively 40 tonnes, 60 tonnes and 80 tonnes in this sequence; and wherein the hot rolling temperature is 60°C, and wherein the electrode foil is heated before the first entry into the hot rolling press, and wherein the temperature of the heating is 40°C.

[0262] The compression density here refers to the compression density when the battery cell is completely discharged, and the test procedure is described below.

[0263] The median C 50The degree of graphitization of the cathode film layer is 1.005; the porosity of the cathode film layer is 16.1%; the iron dissolution rate of the cathode material is 974 ppm; the proportion of the total area of ​​the agglomeration zone of the conductive medium is 1.99%; and the uniformity of distribution of particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 1.85%.

[0264] The cathode foil is cut into strips and punched into a predetermined shape, and the punched cathode foil is sorted by weight in a weighing and sorting machine and stacked in a stacking machine. (3) Production of the anode foil:

[0265] Natural graphite, conductive carbon black, styrene-butadiene rubber (SBR) binder, and sodium carboxymethylcellulose (CMC) thickener are mixed uniformly according to a weight percentage of 95:1:2:2, deionized water is added, and then stirred and dispersed to obtain the anode slurry. The anode slurry is applied to the copper foil of the base material, and then the anode foil is obtained after drying, pressing, cutting, and stacking.

[0266] The anode foil is cut into strips and punched into a predetermined shape, and the punched anode foil is sorted by weight in a weighing and sorting machine and stacked in a stacking machine. (4) Separator

[0267] Polyvinylidene fluoride (PVDF) was dissolved in N-methylpyrrolidone (NMP), stirred thoroughly, and then polyethylene glycol (PEG) was added as a pore-forming agent. The mixture was stirred and mixed sufficiently to obtain the bonding layer solution. This bonding layer solution was applied to the base film with a ceramic layer on both sides. The PEG was dissolved by pre-evaporation at 80°C and drying at 110°C after immersion in deionized water to create a separator with a bonding layer porous on both sides. The base film thickness was 8 µm, the ceramic layer thickness on one side was 3 µm, and the bonding layer thickness on the other side was 1 µm. (5) Electrolyte solution

[0268] The organic solvents dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and ethylene carbonate (EC) were thoroughly mixed in a glove box with an argon atmosphere (H2O<0.1 ppm, O2<0.1 ppm).

[0269] Lithium hexafluorophosphate was then added to dissolve the lithium hexafluorophosphate in the organic solvent, so that the concentration of lithium hexafluorophosphate is 1.05 mol / L, and vinylidene carbonate (VC) is added and stirred homogeneously to obtain the electrolyte solution of embodiment 1.

[0270] In this, based on the total mass of the electrolyte solution, the mass content of dimethyl carbonate is 26%, the mass content of methyl ethyl carbonate is 43.3%, the mass content of vinyl carbonate is 17.3% and the mass content of vinylidene carbonate is 0.9%. (6) Production of the battery

[0271] The stacking machine is used to stack the cathode foil, separator, and anode foil sequentially. The separator should be able to insulate the cathode and anode foils to form the stacked electrical core. The stacked electrical core is then coated with adhesive, which tightly encases it. After the adhesive is applied, the stacked electrical core is placed in the outer packaging, which is a flexible aluminum-plastic film. The aluminum-plastic film consists of an inner layer of polypropylene, an intermediate layer of aluminum foil, and an outer layer of nylon composite. The aluminum-plastic film outer packaging is formed and cut to the desired shape and size using a forming machine. The aluminum-plastic film is then thermally encapsulated to achieve an encapsulation tensile strength of ≥25 N / 8 mm.The batteries are vacuum-baked, rested, injected with electrolyte solution, and encapsulated. The soft-packaged batteries are then hot-pressed and cold-pressed, with the hot-pressing process lasting 45°C, 2 minutes, and applying a pressure of 90 kg / cm². 2 The temperature during cold pressing is 25°C, the time is 2 minutes, and the pressure is 90 kg / cm². 2 The battery cell is obtained after the processes of forming, vacuum extraction, and edge cutting. The battery cell has dimensions of 600 mm in length, 125 mm in width, and 20 mm in thickness.

[0272] The manufacturing process of embodiments 2 to 3 is essentially the same as that of embodiment 1, with the difference that the manufacturing process for the active cathode material and for the cathode foil is adapted as follows: Example 2

[0273] The manufacturing process of embodiment 2 is essentially the same as that of embodiment 1, with the difference that the manufacturing process of the active cathode material and the hot pressing process of the cathode foil are slightly different, and the differences are as follows:

[0274] (1) The carbon source in the mixed raw material is sucrose and glucose, the mass of sucrose being 2 wt% compared to the mass of iron phosphate, and the mass of glucose being 4 wt% compared to the mass of iron phosphate;

[0275] (2) The heating and sintering process differed. The precursor powder was sintered at least twice in a nitrogen atmosphere, with the first sintering temperature being 765°C and the holding time being 8 hours to obtain a first sintered product.

[0276] To the first sintered product, 1.5 wt% (based on the mass of the first sintered product) of glucose, 3.0 wt% (based on the mass of the first sintered product) of polyethylene glycol, titanium dioxide, and vanadium pentoxide are added. The mixture is ground uniformly and then divided into two groups for the second grinding. The two groups had different grinding parameters and were ground to a D v The particle size was set to 50 µm for the particles of the first grinding group and 0.4 µm for the particles of the second grinding group. The ground particles of the first and second groups were mixed in a mass ratio of 30:70 and spray-dried for the second sintering. The temperature for the second sintering is 815°C and the holding time is 10 hours.

[0277] Based on the total mass of the active cathode material, the mass content of Ti element is 1050 ppm and the mass content of V element is 950 ppm.

[0278] (3) The cathode slurry is transferred to an aluminium foil of the collector for drying and coating, and after hot pressing a cathode foil with a one-sided thickness of the cathode film layer of 106.34 µm and a pressing density of 2.37g / cm³ is produced. 3 obtained. The drying temperature is 95°C and the drying rate is 2.0 m / min.

[0279] The hot pressing process comprises at least three hot rolling presses, wherein the hot rolling pressure increases sequentially to 35 tons, 55 tons, and 70 tons in that order; wherein the hot rolling temperature is 65°C; and wherein the electrode foil is heated before the first entry into the hot rolling press, and wherein the heating temperature is 50°C. The pressing density here refers to the pressing density with the battery cell fully discharged, and the test procedure is described below. Example 3

[0280] The manufacturing process of embodiment 3 is essentially the same as that of embodiment 1, with the difference that the sintering process of the active cathode material and the hot pressing process of the cathode foil are particularly different as follows:

[0281] (1) The precursor powder was sintered in two stages at elevated temperature in a nitrogen atmosphere to obtain the active cathode material: The temperature was increased from 25°C to 440°C at a heating rate of 2°C / min (first heating stage) and held for 2.5 hours. The temperature was then increased from 440°C to 760°C at a heating rate of 5°C / min (second heating stage) and held for 11 hours. The active cathode material, consisting of lithium iron phosphate with a carbon material on the surface, was obtained after a further increase in the intensity of the airflow milling.

[0282] (2) The cathode slurry is transferred to an aluminium foil of the collector for drying and coating, and after hot pressing a cathode foil with a one-sided thickness of the cathode film layer of 105.65 µm and a pressing density of 2.36 g / cm³ is produced. 3 obtained. The speed for the coating transfer is 20 m / min.

[0283] The hot pressing process comprises at least three hot rolling presses, wherein the hot rolling pressure increases sequentially and is successively 45 tonnes, 60 tonnes and 80 tonnes in this sequence; and wherein the hot rolling temperature is 60°C, and wherein the electrode foil is heated before the first entry into the hot rolling press, and wherein the temperature of the heating is 40°C.

[0284] The manufacturing process of embodiments 4 to 8 is essentially the same as that of embodiment 1, with the difference that the manufacturing process for the cathode foil is adapted as follows: Example 4

[0285] In embodiment 1, the cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 91.88 µm is obtained by hot pressing; and the cathode foil has a pressing density of 2.36 g / cm³. 3The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 5

[0286] In embodiment 1, the cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 116.09 µm is obtained by hot pressing; and the cathode foil has a pressing density of 2.36 g / cm³. 3The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 6

[0287] In embodiment 1, the cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 72.34 µm is obtained by hot pressing; and the cathode foil has a pressing density of 2.36 g / cm³. 3The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 7

[0288] In embodiment 1, the cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 83.91 µm is obtained by hot pressing; and the cathode foil has a pressing density of 2.36 g / cm³. 3The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 8

[0289] In embodiment 1, the cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 98.93 µm is obtained by hot pressing; and the cathode foil has a pressing density of 2.52 g / cm³. 3The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 9

[0290] The manufacturing process of embodiment 9 is essentially the same as that of embodiment 1, with the difference that the manufacturing process for the active cathode material and for the cathode foil is adapted as follows:

[0291] The precursor solution was initially prepared under argon protection by mixing FeSO4-7H2O, LiOH-H2O, and H3PO4 in deionized water with 0.5 wt% ascorbic acid as an antioxidant. The pH was then adjusted to 5.0, and 0.1 mol / L citric acid was added as a grain growth inhibitor and 1 wt% PEG-4000 as a dispersant. The mixed solution was transferred to a high-pressure reactor and reacted at 180°C for 6 hours. The reaction product was washed by centrifugation, dried under vacuum at 80°C, and finally annealed at 350°C in an argon atmosphere for 2 hours to obtain a lithium iron phosphate material with an average particle size of 160 nm.

[0292] The lithium iron phosphate material produced above and the active cathode material of embodiment 1 are mixed in a mass ratio of 10:90 to obtain the active cathode material of embodiment 9.

[0293] The cathode slurry was transferred to an aluminum foil of the collector for drying and coating. By adjusting the pressure, calendering speed, roller gap, pressure holding time, number of calendering cycles, and controlling the surface density of the coating in the hot-pressing process, the cathode foil with a one-sided cathode film thickness of 105.65 µm was obtained; and the cathode foil has a pressing density of 2.36 g / cm³. 3 The compression density here refers to the compression density when the battery cell is fully discharged, and the test procedure is described below. With the number of stacked film layers remaining unchanged, the thickness of the battery cell was adjusted according to the thickness of the cathode film layer. Example 10

[0294] The manufacturing process of embodiment 10 is essentially the same as that of embodiment 9, with the difference that the manufacturing process for the cathode foil is adapted as follows:

[0295] The active cathode material of embodiment 9 is produced using the same manufacturing process for cathode foil as in embodiment 1, and a cathode foil with a one-sided thickness of the cathode film layer of 105.65 µm is obtained; and the density of the cathode foil is 2.32 g / cm³. 3 The compression density here refers to the compression density when the battery cell is completely discharged, and the test procedure is described below.

[0296] The manufacturing process of comparative example 1 is essentially the same as that of embodiment 1, with the difference that the manufacturing process for the active cathode material is adapted as follows: Comparative example 1

[0297] The manufacturing process of Comparative Example 1 is essentially the same as that of Exemplary Example 1, with the difference that the sintering process of the active cathode material is particularly different as follows:

[0298] The precursor powder was sintered in two stages at elevated temperature in a nitrogen atmosphere to obtain the active cathode material: The temperature was increased from 25°C to 500°C at a heating rate of 2°C / min (first heating stage) and held for 3.5 hours. The temperature was then increased from 500°C to 800°C at a heating rate of 5°C / min (second heating stage) and held for 13 hours. The active cathode material, consisting of lithium iron phosphate with a carbon material on the surface, was obtained after a further reduction in the intensity of the airflow milling.

[0299] The manufacturing process of comparative example 2 is essentially the same as that of embodiment 1, with the difference that the manufacturing process for the active cathode material is adapted as follows: Comparative example 2

[0300] The precursor solution was initially prepared under argon protection by mixing FeSO4-7H2O, LiOH-H2O, and H3PO4 in deionized water with 0.5 wt% ascorbic acid as an antioxidant. The pH was then adjusted to 5.0, and 0.1 mol / L citric acid was added as a grain growth inhibitor and 1 wt% PEG-4000 as a dispersant. The mixed solution was transferred to a high-pressure reactor and reacted at 180°C for 6 hours. The reaction product was washed by centrifugation, dried under vacuum at 80°C, and finally annealed at 350°C in an argon atmosphere for 2 hours to obtain a lithium iron phosphate material with an average particle size of 160 nm.

[0301] The lithium iron phosphate material produced above and the active cathode material of embodiment 1 are mixed in a mass ratio of 12:88 to obtain the active cathode material of comparative example 2.

[0302] It is understood that the manufacturing processes for the cathode foil are the same in embodiment 1, embodiment 10 and comparative example 2; in embodiment 9 and embodiment 10 the same manufacturing process is used for the active cathode material, but the manufacturing process for the cathode foil is different. Test procedure: 1. Battery cell capacity

[0303] The battery is charged at 25°C with a charging rate of 0.5 C of the nominal capacity of the battery cell to 3.65 V, then charged with a constant voltage of 3.65 V to 0.05 C and left to stand for 10 minutes, then discharged with a discharge rate of 1C to 2.5 V and left to stand for 10 minutes, and the capacity C in units of Ah is calculated during the discharge process according to the formula C=I*t. 2. Number of cycles corresponds to a drop in capacity to 85%

[0304] The battery is charged at 25°C with a charging rate of 0.5C of the nominal capacity of the battery cell to 3.65V, then charged with a constant voltage of 3.65V to 0.05C and left to stand for 10 minutes. The above single charge / discharge is one cycle until the battery capacity drops to 85% of the nominal capacity to end the test, which is recorded as the number of cycles at 85% SOH. Test result Table 1 cathode foil Battery cell capacity Ah The number of cycles corresponds to a decreasing capacity to 85% per cycle. Area fraction Thickness direction Electrode foil Percentage of area fraction of particles with a particle size greater than or equal to 1µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil Cathode foil density g / cm³ 3 when the battery cell is completely discharged Percentage of surface area of ​​particles with a particle size of 50 nm-200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil Median L A50 the sphericity in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm Specific resistance of the cathode film layer Ω*cm One-sided thickness of the cathode film layer µm Implementation example 1 36,64% 2,36 6,49% 0,687 32,2 105,64 160 1514 Implementation example 2 49,96% 2,37 5,91% 0,72 33,67 106,34 161 1479 Implementation example 3 12,02% 2,36 5,33% 0,75 31,5 105,65 159 1554 Implementation example 4 38,09% 2,36 6,52% 0,67 30,73 91,88 140 1491 Implementation example 5 38,44% 2,36 6,55% 0,653 34,49 116,09 177 1476 Implementation example 6 36,29% 2,36 6,35% 0,69 29,88 72,34 110 1601 Implementation example 7 36,37% 2,36 6,42% 0,688 30,55 83,91 128 1568 Implementation example 8 36,88% 2,52 6,54% 0,685 29,72 98,93 159 1499 Implementation example 9 36,74% 2,36 14,81% 0,686 34,76 105,65 160 1493 Implementation example 10 36,78% 2,32 14,78% 0,686 34,98 105,65 160 1502 Comparative example 1 55,91% 2,36 5,19% 0,631 36,37 105,44 159 1424 Comparative example 2 33,04% 2,28 15,67% 0,686 38,76 105,63 160 1460

[0305] As can be seen from the comparison of the embodiments and the comparative examples, in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the percentage area fraction of particles with a particle size of more than or equal to 1 µm is 12%–50%, and the percentage area fraction of particles with a particle size of more than or equal to 50 nm and less than or equal to 200 nm is 3.0%–15.0%. When the battery cell is in a fully discharged state and the density of the cathode foil is 2.3 g / cm³ 3 -2.6 g / cm² 3 If the voltage concentration of large particles during the pressing process of the cathode foil is reduced, the cathode foil has a low specific electrical resistance and improves the cycle performance and kinetic performance of the battery.

[0306] As can be seen from the comparison between embodiment 2 and embodiments 1 and 3, in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the percentage area fraction of particles with a particle size of more than or equal to 1 µm is 12% to 40%, which helps the battery to maintain a high capacity, while further improving the phenomenon of the tension concentration of the large particles during the pressing process of the electrode foil, reducing the probability of the film layer loosening and the active substance falling off, and improving the cycle performance of the battery.

[0307] As can be seen from the comparison between embodiment 9 and embodiments 1 to 3, in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm is 5%-10%, which contributes to reducing the specific electrical resistance of the cathode film layer and improving the kinetic performance of the battery based on maintaining a high capacity and good cycle performance of the battery.

[0308] As can be seen from the comparison between embodiment 5 and embodiments 1 to 4 and 6 to 9, in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the median LA50 of the sphericity in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of more than or equal to 1 µm is 0.67 to 0.75, which further improves the phenomenon of the tension concentration of the large particles during the pressing process of the electrode foil, reduces the probability that the film layer loosens and the active substance falls off, and improves the cycle performance of the battery.

[0309] As can be seen from the comparison between embodiments 6 and 7 and embodiments 4 and 5, the one-sided thickness of the cathode film layer is 90 µm-120 µm, which contributes to a further improvement in the battery capacity.

[0310] It should be noted that the present application is not limited to the embodiments mentioned above. The embodiments mentioned above are only examples, and embodiments within the scope of the technical solution of the present application that have essentially the same composition as the technical idea and have the same effect are included in the technical scope of the present application. Furthermore, within the scope of the present application, other possibilities for constructing the embodiments by combining some of the constituent elements of the embodiments and applying various deformations to the embodiments that a person skilled in the art can imagine without departing from the subject matter of the present application are also included. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] GB / T 33822-2017

[0189]

Claims

Battery cell, characterized in that it comprises a stacked electrical core, wherein the stacked electrical core comprises a cathode foil and an anode foil, wherein the cathode foil comprises a cathode collector and a cathode film layer provided on at least one side of the cathode collector, wherein the cathode film layer comprises lithium-containing transition metal phosphate particles, wherein at least a part of the surface of the lithium-containing transition metal phosphate particles is provided with a carbon material; wherein a percentage area fraction of the particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%;wherein the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 3.0%–15.0%; wherein a density of the cathode foil when the battery cell is in a fully discharged state is 2.3 g / cm³–2.6 g / cm³. Battery cell according to claim 1, characterized in that the percentage area fraction of particles with a particle size of more than or equal to 1 µm and less than or equal to 5 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 12%-50%, optionally 12%-40%. Battery cell according to claim 1 or 2, characterized in that the distribution uniformity of the particles with a particle size of more than or equal to 1 µm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 0.2%-5%, optionally 0.2%-2%. Battery cell according to one of claims 1 to 3, characterized in that in a cumulative distribution curve of the sphericity area of ​​the particles with a particle size of more than or equal to 1 µm in the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil the median LA50 of the sphericity is 0.6-0.8, optionally 0.65-0.75, further optionally 0.67-0.

75. Battery cell according to one of claims 1 to 4, characterized in that the percentage area fraction of particles with a particle size of more than 50 nm and less than or equal to 200 nm in a cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil is 5.0%-15.0%, optionally 5.0%-10.0%. Battery cell according to one of claims 1 to 5, characterized in that a one-sided thickness of the cathode film layer is 70 µm-120 µm, optionally 90 µm-120 µm, further optionally 100 µm-120 µm. Battery cell according to one of claims 1 to 6, characterized in that the cathode film layer further comprises a conductive means, wherein, with reference to a total area of ​​the cross-sectional area of ​​the cathode film layer along the thickness direction of the electrode foil, the proportion of the total area of ​​an agglomeration region of the conductive means is 0.2%-6%, optionally 1.5%-5%. Battery cell according to claim 7, characterized in that the conductive means comprises carbon nanotubes, wherein the carbon nanotubes comprise one or more of single-walled carbon nanotubes, thin-walled carbon nanotubes, multi-walled carbon nanotubes, wherein the conductive means further optionally comprises conductive carbon black. Battery cell according to claim 7 or 8, characterized in that the agglomeration area of ​​the conductive agent comprises carbon nanotubes and conductive carbon black. Battery cell according to claim 9, characterized in that, with respect to the mass of the cathode film layer, the mass content C1 of the carbon nanotubes is 0 <C1<2,5% und der Massengehalt C2 des leitfähigen Rußes 0<C1:52,5% erfüllt. Battery cell according to one of claims 1 to 10, characterized in that the cathode film layer further comprises a dispersing agent, wherein the dispersing agent comprises hydrogenated nitrile butadiene rubber HNBR. Battery cell according to claim 11, characterized in that the mass content of the dispersing agent is 0.5%-2% in relation to the mass of the cathode film layer. Battery cell according to one of claims 1 to 12, characterized in that the cathode film layer is provided with a lower coating layer in a lower region facing the cathode collector, wherein the lower coating layer fulfills at least one of the following conditions: (1) the lower coating layer comprises a conductive agent and a binder, wherein the conductive agent comprises carbon nanotubes and conductive carbon black, and wherein the binder comprises a vinylidene fluoride polymer; (2) the thickness of the lower coating layer is 0.5 µm-5 µm. Battery cell according to one of claims 1 to 13, characterized in that the median C50 of the graphitization degree in the cumulative distribution curve for a graphitization C value of the cathode film layer obtained in an area scanning mode of the laser microconfocal Raman spectrometer is greater than 0.95 and less than or equal to 1.20; wherein the graphitization C value is IG / ID, where IG represents the intensity of the G-peak of the Raman spectrum at 1580±100cm-1 and ID represents the intensity of the D-peak of the Raman spectrum at 1350±100cm-1. Battery cell according to one of claims 1 to 14, characterized in that the lithium-containing transition metal phosphate particles in the cathode film layer comprise a component with a general formula as follows: LimFexPyOjQqFormula 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, and where 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, 0≤q≤0.

1. Battery cell according to one of claims 1 to 15, characterized in that the lithium-containing transition metal phosphate particles comprise titanium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of titanium is 500 ppm-8000 ppm, optionally 1000 ppm-3000 ppm. Battery cell according to one of claims 1 to 16, characterized in that the lithium-containing transition metal phosphate particles comprise vanadium, wherein, based on the total mass of the lithium-containing transition metal phosphate particles in the cathode film layer, the mass content of vanadium is 500 ppm-5000 ppm, optionally 500 ppm-3000 ppm. Battery cell according to one of claims 1 to 17, characterized in that the porosity of the cathode film layer is 14%-28%. Battery cell according to one of claims 1 to 18, characterized in that the specific resistance of the cathode film layer is 10 Ω·cm-35 Ω·cm. Battery cell according to one of claims 1 to 19, characterized in that the battery cell further comprises a separator arranged between the cathode foil and the anode foil, wherein the separator comprises a base film and a ceramic layer provided on both sides of the base film, and a bonding layer provided on at least one of the sides of the ceramic layer facing away from the base film, wherein the bonding layer is a continuous layer with a porous structure, and wherein the bonding layer comprises a vinylidene fluoride polymer. Battery cell according to one of claims 1 to 20, characterized in that the battery cell comprises a housing, wherein the stacked electrical core is received in the housing, wherein the housing has a dimension of L0 in a longitudinal direction, wherein the housing has a dimension of W0 in a width direction, wherein the housing has a dimension of H0 in a thickness direction, wherein 450 mm ≤ L0 ≤ 1300 mm, 100 mm ≤ WO ≤ 150 mm, and 14 mm ≤ H0 ≤ 22 mm. Battery cell according to claim 21, characterized in that the dimension L0 of the housing in the longitudinal direction meets the following condition: 450 mm ≤ L0 ≤ 650 mm. Battery cell according to claim 21, characterized in that the dimension L0 of the housing in the longitudinal direction meets the following condition: 900 mm ≤ L0 ≤ 1300 mm. Battery cell according to one of claims 20 to 23, characterized in that the housing meets at least one of the following conditions: (1) the housing material is a soft packaging material, wherein the soft packaging material comprises an aluminum-plastic composite film, optionally a composite film formed from one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), polyethylene (PE) with aluminum; (2) the housing comprises a first sealing zone, wherein the first sealing zone is provided at at least one laterally extending end of the stacked electrical core;(3) the first sealing zone comprises a longitudinally extending folded edge structure, the folded edge structure being provided with an encapsulating adhesive, the encapsulating adhesive being applied successively along the longitudinal direction and securing the folded edge structure; (4) the housing comprises at least one second sealing zone, the second sealing zone being provided at at least one end of the stacked electrical core along the longitudinal direction of the housing, the second sealing zone being provided on one side of the electrode tab of the stacked electrical core. Battery cell block according to one of claims 1 to 24, characterized in that a plurality of adhesive rings circumferentially in the width direction are provided around an outer circumference of the stacked electrical core, wherein the adhesive rings circumferentially in the width direction are provided at intervals along the length direction. Battery cell according to one of claims 1 to 25, characterized in that the capacity of the battery cell at 25°C is 100 Ah-300 Ah, optionally 110 Ah-190 Ah, further optionally 125 Ah-180 Ah. Battery device characterized in that it comprises a battery cell according to one of claims 1 to 26. Power-consuming device, characterized in that the power-consuming device comprises a battery device according to claim 27, wherein the battery device is used to provide electrical energy. Energy storage device characterized in that the energy storage device comprises a battery device according to claim 27, wherein the battery device is used for storing electrical energy.

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