Battery cells, battery devices, power consumption devices, and energy storage devices

Abstract

The application discloses a battery monomer, a battery device, a power utilization device and an energy storage device. The battery monomer comprises a laminated core, the laminated core comprises a positive pole piece, a negative pole piece and a diaphragm arranged between the positive pole piece and the negative pole piece; the positive pole piece comprises a positive pole current collector and a positive pole film layer arranged on at least one side of the positive pole current collector, the positive pole film layer comprises lithium-containing transition metal phosphate particles, and at least part of the surfaces of the lithium-containing transition metal phosphate particles are provided with carbon materials; in a section of the positive pole film layer along a thickness direction of the pole piece, the area proportion of particles with a particle size greater than or equal to 1 mu m is 12% to 50%; the diaphragm comprises a base film, ceramic layers arranged on both sides of the base film and a bonding layer arranged on the side of the ceramic layer far away from the base film and close to the positive pole piece, the bonding layer is a continuous layer with a porous structure, and the bonding layer comprises a vinylidene fluoride polymer.

Description

[0001] This application claims priority to International Application PCT / CN2025 / 094374 entitled "Battery Cell, Battery Device, Electric Device and Energy Storage Device" filed on May 12, 2025, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery cells, and in particular to a battery cell, a battery device, an electric device and an energy storage device. BACKGROUND

[0003] In recent years, battery cells are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0004] With the increasing demand for the endurance mileage and cycle life of electric devices, higher requirements are also placed on the capacity and cycle performance of battery cells. However, it is difficult to simultaneously improve the above-mentioned performances in the prior art, which is a technical problem that needs to be solved in the field. SUMMARY

[0005] The present application is made in view of the above-mentioned problems, and aims to provide a battery cell with high capacity and good cycle performance.

[0006] The first aspect of the present application provides a battery cell, comprising a laminated cell, the laminated cell comprising a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer comprising lithium-containing transition metal phosphate particles, at least part of the surface of the lithium-containing transition metal phosphate particles being provided with a carbon material; in a section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of particles with a particle size greater than or equal to 1 μm is 12%-50%; the separator comprises a base film, ceramic layers disposed on both sides of the base film, and a bonding layer disposed on the side of the ceramic layer away from the base film at least close to the positive electrode sheet, the bonding layer being a continuous layer of porous structure, and the bonding layer comprising a vinylidene fluoride polymer.

[0007] Applicants have found that when the area ratio of particles with a particle size greater than or equal to 1 μm in a section of the positive electrode film layer along the thickness direction of the electrode sheet is less than 12%, the lack of particle grading will significantly limit the space for improving the compaction density, making it difficult to effectively improve the battery capacity. When the area ratio of particles with a particle size greater than or equal to 1 μm in a section of the positive electrode film layer along the thickness direction of the electrode sheet is greater than 50%, the excessive large particles will cause a serious rebound phenomenon in the positive electrode film layer, leading to damage of the SEI film and cracking of the film layer, increasing the risk of short circuit and adversely affecting the cycle performance of the battery.

[0008] The embodiments of the present application improve the battery capacity by using the laminated cell with the lithium-containing transition metal phosphate positive electrode film layer containing a certain amount of large particles, further use the separator with ceramic layers on both sides to increase the stiffness of the separator, and use the separator with a porous structure of a continuous layer with a larger bonding area and stronger bonding force to increase the bonding effect of the separator and the positive electrode sheet, improve the compactness and stiffness of the laminated cell inside the group, make up for the deficiency of small external restraint force of the laminated cell, reduce the risk of mutual extrusion of the positive and negative electrode sheets in the thickness direction of the cell during the rebound process to the horizontal direction misalignment, reduce the risk of positive and negative electrode overlap and further cause short circuit, so that the battery further improves the cycle performance on the basis of good capacity.

[0009] In any embodiment, the area ratio of particles with a particle size of 1-5 μm in the cross section of the positive electrode film layer along the thickness direction of the electrode sheet is 12-50%.

[0010] The area ratio of particles with a particle size of 1-5 μm in the cross section of the positive electrode film layer along the thickness direction of the electrode sheet is within the above range, which is beneficial to improve the rebound phenomenon of large particles in the electrode sheet during the battery cycle process on the basis of maintaining high capacity, and improve the cycle performance of the battery.

[0011] In any embodiment, the area ratio of particles with a particle size of 1-5 μm in the cross section of the positive electrode film layer along the thickness direction of the electrode sheet is 12-40%.

[0012] The area ratio of particles with a particle size of 1-5 μm in the cross section of the positive electrode film layer along the thickness direction of the electrode sheet is within the above range, which is beneficial to further improve the electrode sheet rebound phenomenon caused by stress concentration of large particles in the electrode sheet on the basis of maintaining high capacity, reduce the probability of contact between the positive electrode film layer and the negative electrode film layer of the electrode sheet and cause short circuit, and further improve the cycle performance of the battery.

[0013] In any embodiment, the vinylidene fluoride polymer includes one or more of a vinylidene fluoride homopolymer (PVDF) and a copolymer of vinylidene fluoride and hexafluoropropylene.

[0014] In any embodiment, the single-sided thickness of the positive electrode film layer is 70-120 μm.

[0015] The specific capacity of lithium-containing transition metal phosphate particles is relatively low. Research shows that when the single-sided thickness of the positive electrode film layer is less than 70 μm, the battery capacity is difficult to meet market demand. The single-sided thickness of the positive electrode film layer is within the above range, which is beneficial to improve the capacity of the battery monomer.

[0016] In any embodiment, the single-sided thickness of the positive electrode film layer is 90-120 μm.

[0017] The single-side thickness of the positive electrode film layer is within the above range, which is beneficial to further improve the capacity of the battery.

[0018] In any embodiment, the single-side thickness of the positive electrode film layer is 100 μm-120 μm.

[0019] Increasing the single-side thickness of the positive electrode film layer is beneficial to improve the capacity of the battery. The applicant finds that when the single-side thickness of the positive electrode film layer is greater than or equal to 100 μm, the phenomenon of particle rebound in the positive electrode film layer is more serious. The embodiments of the present application effectively alleviate the serious rebound of the thick coated film layer in the stacked cell, and the battery has improved cycle performance on the basis of maintaining high capacity.

[0020] In any embodiment, the positive electrode film layer comprises a first region, the first region is located at the top of the positive electrode film layer away from the positive electrode current collector, and the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region is 0.2%-5%.

[0021] In any embodiment, the positive electrode film layer comprises a first region, the first region is located at the top of the positive electrode film layer away from the positive electrode current collector, and the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region is 0.2%-3.5%.

[0022] The stress concentration degree of large particles and small particles in the positive electrode film layer is different, and with the gradual release of stress in the cycle process, the pole piece appears different degrees of rebound. In the embodiments of the present application, large particles have a certain content, and the large particles are uniformly distributed in the pole piece, so that the extrusion force of the positive electrode film layer on the separator presents uniform distribution, reduces the risk of local excessive extrusion and local lithium ion transmission path blockage caused by uneven distribution of large particles, which increases the current density around and is prone to lithium precipitation, so that the battery further improves the cycle performance of the battery on the basis of having good capacity.

[0023] In any embodiment, in the section of the positive electrode film layer along the thickness direction of the pole piece, in the spheroidicity area cumulative distribution curve of particles with a particle size greater than or equal to 1 μm, the median number L A50 of spheroidicity is 0.6-0.8.

[0024] The median number of spheroidicity of particles with a particle size greater than or equal to 1 μm is within the above range, the large particles have good spheroidicity, which reduces the particle bridging caused by irregular shape of large particles, reduces the void content in the pole piece, and reduces the stress concentration caused by irregular large particles, reduces the rebound of the pole piece in the cycle process caused by stress release, so that the battery monomer has further improved cycle performance while having high capacity.

[0025] In any embodiment, in a section of the positive electrode film layer along the thickness direction of the electrode tab, the median value L of the sphericity of the particles with a particle size greater than or equal to 1 μm in the sphericity area cumulative distribution curve of the particles is 0.65-0.75. A50

[0026] The median value of the sphericity of the particles with a particle size greater than or equal to 1 μm in the above range is beneficial to reduce the stress concentration of large particles due to the irregularity of large particles, reduce the rebound of the electrode tab caused by stress release during the cycle process, and improve the cycle performance of the battery.

[0027] In any embodiment, in a section of the positive electrode film layer along the thickness direction of the electrode tab, the median value L of the sphericity of the particles with a particle size greater than or equal to 1 μm in the sphericity area cumulative distribution curve of the particles is 0.65-0.75. A50

[0028] The median value of the sphericity of the particles with a particle size greater than or equal to 1 μm in the above range can further improve the stress concentration of large particles, reduce the rebound of the electrode tab caused by stress release during the cycle process, and further improve the cycle life of the battery cell.

[0029] In any embodiment, in a cumulative distribution curve of the graphitization degree C value of the positive electrode film layer obtained under the face scanning mode of a laser microscopic confocal Raman spectrometer, the median value C of the graphitization degree is greater than or equal to 0.95 and less than or equal to 1.20. 50 The graphitization degree C value is I G / I D , I G represents the G peak intensity of the Raman spectrum at 1580±100 cm -1 , and I D represents the D peak intensity of the Raman spectrum at 1350±100 cm -1 .

[0030] In a cumulative distribution curve of the graphitization degree C value of the positive electrode film layer obtained under the face scanning mode of a laser microscopic confocal Raman spectrometer, the median value C of the graphitization degree is greater than or equal to 0.95 and less than or equal to 1.20. 50 The above range can further improve the compaction density of the electrode tab, so that the content of large-size particles in the positive electrode film layer can be reduced, which is helpful to reduce the rebound phenomenon of the film layer caused by too many large particles on the basis of maintaining the capacity of the battery, and further improve the cycle performance of the battery.

[0031] In any embodiment, in a cumulative distribution curve of the coating value B of the positive electrode film layer obtained under the face scanning mode of a laser microscopic confocal Raman spectrometer, the median value B of the coating value is 0.30-0.60. 50 The coating value B is IP / ID, wherein IP represents the Raman spectrum at 948±100 cm -1 ​​P peak intensity, ID represents the D peak intensity of the Raman spectrum at 1350±100 cm -1 P peak intensity, ID represents the D peak intensity of the Raman spectrum at 1350±100 cm

[0032] The median value of the coating value of the positive electrode film layer B 50 The above range indicates that the surface carbon material layer of the positive electrode active material is relatively dense and uniform, which is beneficial to improve the uniformity of the positive electrode film layer in the rolling process and reduce the stress concentration phenomenon in the positive electrode film layer. In addition, with the aid of the dense and uniform carbon material layer, the large particles in the positive electrode film layer are more likely to slip during the compaction process, thereby reducing the stress concentration phenomenon at the large particles in the positive electrode film layer, reducing the rebound caused by the stress release at the large particles during the cycle process, and improving the cycle life of the battery.

[0033] In any embodiment, the iron dissolution rate of the positive electrode material is 658 ppm-1921 ppm, and optionally 658 ppm-1485 ppm.

[0034] The dissolved iron element in the positive electrode material mainly comes from the lithium-containing transition metal phosphate particles of the positive electrode active material. The iron dissolution rate depends on the number of lattice defects in the lithium-containing transition metal phosphate particles and the completeness and density of the carbon material layer on the surface of the positive electrode active material. The lower the iron dissolution rate means that there are fewer lattice defects in the lithium-containing transition metal phosphate particles, which is beneficial to reduce the corrosion of the lattice in a weak acid environment. The more complete and dense the carbon material layer on the surface of the positive electrode active material, the more it inhibits the dissolution of iron ions in a weak acid environment. The positive electrode material with an iron dissolution rate in the above range has relatively few lattice defects and a complete and dense carbon material layer, which is beneficial to improve the pressure resistance and easy sliding degree of the particles in the positive electrode film layer under large rolling pressure, improve the compaction density of the positive electrode film layer and reduce the stress concentration in the positive electrode film layer, improve the rebound phenomenon caused by stress concentration of large particles, and further improve the cycle performance of the battery on the basis of good capacity.

[0035] In any embodiment, the lithium-containing transition metal phosphate particles in the positive electrode film layer include components represented by the following general formula: Li m Fe x P y O j Q q Formula I, wherein Q includes 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, 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, 0≤q≤0.1.

[0036] In any embodiment, the lithium-containing transition metal phosphate particles include titanium. Based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of titanium is 500ppm-8000ppm, and can be optionally 1000ppm-3000ppm.

[0037] The introduction of titanium elements into lithium-containing transition metal phosphate particles requires the addition of a titanium source during the preparation of the positive electrode active material. Titanium sources are often inert materials, and adhering to the surface of the raw materials containing lithium transition metal phosphate particles can reduce the reaction activity and reduce the growth of particle size. Increasing the graphitization degree of the positive electrode active material often requires a higher sintering temperature or a longer sintering time, but this will also increase the size of the particles in the positive electrode film layer, increase the stress concentration of the positive electrode film layer, and increase the rebound of the electrode during the cycle. In the embodiment of the present application, by adding a high content of titanium elements to the lithium-containing transition metal phosphate particles, the reaction activity of the raw materials for synthesizing the positive electrode active material is reduced, so that the positive electrode active material can achieve control of the proportion of large particles while having a high degree of graphitization, reduce the stress concentration of the positive electrode film layer, and improve the rebound phenomenon caused by stress concentration at large particles, so that the battery has a good capacity and further improves the cycle performance of the battery.

[0038] At the same time, doping titanium into the positive electrode active material helps cause lattice distortion, reduce Li-O bond energy, increase lithium ion transfer rate, and improve the battery's kinetic performance. Lithium ion diffusion in the positive electrode film is uneven, often accompanied by a significant lithium ion concentration gradient. The present invention improves the solid-phase transfer rate of the positive electrode active material by adding a high content of titanium to lithium-containing transition metal phosphate particles, thereby improving the battery's kinetics.

[0039] In any embodiment, the lithium-containing transition metal phosphate particles include vanadium. Based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of vanadium is 500ppm-5000ppm, and can be optionally 500ppm-3000ppm.

[0040] The vanadium element in the positive electrode film can be in a variety of valence states, among which the +5 valence vanadium (V 5+ ) can be doped in the phosphorus element site, because its large radius can cause lattice distortion, expand the diffusion channel of lithium ions, thereby improving the ionic conductivity of the positive electrode active material and improving the kinetic performance of the battery; + trivalent vanadium (V 3+ ) can be doped into transition metal sites, generating lithium vacancies through charge compensation, thereby improving the electronic conductivity of the cathode active material. Furthermore, the improved uniformity of vanadium distribution within the lithium-containing transition metal phosphate particles helps further enhance the kinetic performance and reaction uniformity of the cathode film, thereby further improving the kinetic performance and cycling performance of the battery cells.

[0041] A vanadium content within the above range helps improve the kinetic performance of the positive electrode sheet and, consequently, the kinetic performance of lithium-containing transition metal phosphate batteries. Furthermore, the synergistic effect of titanium, vanadium, and carbon nanotubes in the positive electrode film helps form a well-defined three-dimensional network, further enhancing the electronic and ionic conductivity of the positive electrode film, thereby further improving the kinetic performance of lithium-containing transition metal phosphate batteries.

[0042] In any embodiment, the positive electrode film layer further includes a conductive agent. Based on the total area of ​​the cross section of the positive electrode film layer along the thickness direction of the electrode sheet, the total area of ​​the agglomerated region of the conductive agent accounts for 0.2%-6%, and can be optionally 1.5%-5%.

[0043] Based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode, the total area ratio of the agglomerated region of the conductive agent is within the above range, indicating that the conductive agent is evenly dispersed in the positive electrode film layer and is easy to form a uniform conductive network, which is beneficial to reduce the local polarization and even lithium plating problems generated by the battery during the cycle process.

[0044] At the same time, studies have shown that large-sized particles in lithium-containing transition metal phosphate particles are prone to rebound. The agglomeration area of ​​the conductive agent within the above range can suppress the rebound of the lithium-containing transition metal phosphate particles with the help of the uniform distribution of the conductive agent, form mechanical constraints on the particles and even the film layer, improve the cohesion of the film layer, reduce the damage of the SEI film and the film layer during the rebound of the film layer, and improve the cycle life of the battery.

[0045] In any embodiment, the conductive agent includes carbon nanotubes, and the carbon nanotubes include one or more of single-walled carbon nanotubes, few-walled carbon nanotubes, and multi-walled carbon nanotubes. Optionally, the conductive agent further includes conductive carbon black.

[0046] Carbon nanotubes have a high aspect ratio, which is conducive to overlapping multiple positive electrode particles in the thickness direction, forming a long-range conductive path while increasing the binding force between particles, reducing local polarization and even lithium plating problems generated by the battery during the cycle process, and improving the cycle life of the battery; it can also reduce the rebound phenomenon of large particles in the positive electrode film layer through the binding effect, and improve the cycle performance of the battery.

[0047] Conductive carbon black, with its small size, adheres to the surface of the cathode particles and fills the gaps between them, forming dense, point-like conductive contacts. When used in conjunction with carbon nanotubes, it balances both long-range and short-range conductivity, further improving the conductive network within the cathode film. Furthermore, the conductive agent's large surface area facilitates liquid absorption and retention, reducing electrolyte extrusion caused by the electrode's increased expansion force during long cycling cycles and improving the battery's cycle life.

[0048] In any embodiment, the agglomeration region of the conductive agent comprises carbon nanotubes and conductive carbon black.

[0049] The researchers found that carbon nanotubes are prone to agglomeration due to their high surface energy, resulting in uneven dispersion in the positive electrode film layer and the inability to form an effective carbon nanotube network structure. The surface energy of conductive carbon black and carbon nanotubes is relatively close, and it can be adsorbed on the surface of carbon nanotubes to form a physical barrier, increase the resistance of carbon nanotube agglomeration, reduce direct contact between carbon nanotubes, and thus inhibit the agglomeration phenomenon, improve the uniformity of carbon nanotubes in the positive electrode film layer. On the one hand, this helps to improve the conductivity of the positive electrode film layer and improve the dynamic performance of the battery; on the other hand, it helps to exert the binding effect of carbon nanotubes on the positive electrode film layer, reduces the risk of positive electrode film layer falling off, and further improves the dynamic performance and cycle life of the battery. In addition, the agglomeration of carbon nanotubes in the conductive agent agglomeration region will also cause the local ion transport path of the conductive agent agglomeration region to be blocked, and the addition of conductive carbon black can improve the lithium ion transport capacity of this region, reduce local polarization, and further improve the cycle stability of the battery.

[0050] In any embodiment, the mass content C1 of carbon nanotubes satisfies: 0 < C1 ≤ 2.5%, and the mass content C2 of conductive carbon black satisfies: 0 < C1 ≤ 2.5%, based on the mass of the positive electrode film layer.

[0051] The mass content of carbon nanotubes and conductive carbon black within the above range can effectively alleviate the agglomeration of carbon nanotubes and form a good conductive network structure, thereby effectively reducing the stress concentration of the positive electrode film layer and improving the liquid retention rate of the positive electrode film layer during long-term cycling, further reducing the risk of positive electrode film layer falling off and the degree of polarization, and improving the dynamic performance of the battery and the cycle life of the battery.

[0052] In any embodiment, the positive electrode film layer further comprises a dispersant, and the dispersant comprises hydrogenated nitrile rubber HNBR.

[0053] The polar groups (such as cyano, -CN) in the hydrogenated nitrile rubber HNBR molecule can interact (such as hydrogen bonding, dipole interaction) with the hydroxyl (-OH) or metal oxide sites on the surface of the lithium-containing transition metal phosphate particles, enhancing the compatibility of the particles with the solvent, reducing the interfacial tension of the particles with the solvent, especially the interfacial tension of large particles, making the particles more easily uniformly dispersed, reducing aggregation caused by hydrophobicity, improving the dispersibility of large particles in the positive electrode film layer, and reducing the stress concentration generated during the die cutting process of the positive electrode film layer.

[0054] At the same time, during the drying of the slurry into a film, the elastic network structure of HNBR can buffer the shrinkage stress generated by solvent evaporation, reduce the re-aggregation of conductive agents due to capillary forces during this process, reduce the area ratio of the conductive agent agglomeration region, and improve the cycle life of the battery.

[0055] In any embodiment, the mass content of the dispersant is 0.5%-2% based on the mass of the positive electrode film layer.

[0056] The mass content of the dispersant in the above range can achieve uniform dispersion of the particles in the positive electrode film layer while maintaining a high loading amount of the positive electrode film layer, and the battery has good capacity and cycle performance.

[0057] In any embodiment, the compaction density of the positive electrode tab is 2.3g / cm 3 -2.6g / cm 3 .

[0058] In any embodiment, the porosity of the positive electrode film layer is 14%-28%.

[0059] The porosity of the positive electrode film layer in the above range is beneficial on the one hand to improve the liquid retention properties of the electrolyte, improve the ion diffusion of the positive electrode film layer with a certain area ratio of large particles, and improve the kinetic performance of the battery.

[0060] In any embodiment, the positive electrode film layer is provided with a bottom coating layer at the bottom region close to the positive electrode current collector, the bottom coating layer comprises a conductive agent and a binder, the conductive agent comprises carbon nanotubes and conductive carbon black, and the binder comprises a vinylidene fluoride polymer.

[0061] In any embodiment, the positive electrode film layer is provided with a bottom coating layer at the bottom region close to the positive electrode current collector, and the thickness of the bottom coating layer is 0.5μm-5μm.

[0062] The bottom coating layer provided by the embodiments of the present application helps to improve the adhesion of the positive electrode film layer to the positive electrode current collector and alleviate the stress concentration phenomenon at large particles, thereby reducing the probability of positive electrode film layer falling off and improving the cycle stability of the battery. At the same time, compared with the direct contact between the positive electrode current collector and the positive electrode film layer, the contact area between the bottom coating layer and the positive electrode film layer is increased, which helps to increase the area of electron transmission between the current collector and the positive electrode film layer, thereby reducing the internal resistance of the tab and improving the kinetic performance of the battery.

[0063] In any embodiment, the thickness of the base film is 7μm-9μm.

[0064] In any embodiment, the single-sided thickness of the ceramic layer is 2μm-4μm.

[0065] In any embodiment, the single-sided thickness of the adhesive layer is 1μm-5μm.

[0066] The thickness of the bonding layer is too low, the space for buffering expansion in the diaphragm is small, and the bonding force between the diaphragm and the pole piece is low. On the one hand, the stress of the membrane layer increases after the expansion of the membrane layer, the probability of the membrane layer falling off increases, which affects the cycle life of the battery. On the other hand, the probability of positive negative overlap short circuit increases, thereby affecting the safety performance of the battery. The thickness of the bonding layer is too large, which occupies a large space of the battery, thereby affecting the volume energy density of the battery. In the embodiments of the present application, the thickness of the bonding layer is within the above range, which helps to balance the cycle life, safety performance and volume energy density of the battery.

[0067] In any embodiment, the battery monomer includes a shell, the laminated core is accommodated in the shell, the size of the shell in the length direction is L0, the size of the shell in the width direction is W0, and the size of the shell in the thickness direction is H0, 450mm≤L0≤1300mm, 100mm≤W0≤150mm, and 14mm≤H0≤22mm.

[0068] The size of the shell of the battery monomer in the embodiments of the present application is within the above range, which is beneficial to the battery to achieve better capacity.

[0069] In any embodiment, the size L0 of the shell in the length direction satisfies: 450mm≤L0≤650mm.

[0070] When the size L1 of the shell in the length direction satisfies 450mm≤L1≤650mm, the length of the battery monomer is shorter, which helps to shorten the diffusion path of the current, reduce the internal resistance of the pole piece, thereby reduce the heat production of the battery and improve its kinetic performance. In addition, the shorter length of the shell helps to shorten the diffusion path of the electrolyte in the infiltration process, improve the infiltration rate and uniformity of the electrolyte, further promote the uniformity of lithium ion deintercalation in the cycle process, relieve stress concentration phenomenon, reduce the rebound degree of the membrane layer, and improve the cycle stability of the battery monomer.

[0071] In any embodiment, the size L0 of the shell in the length direction satisfies: 900mm≤L0≤1300mm.

[0072] When the size L1 of the shell in the length direction satisfies 900mm≤L1≤1300mm, the size of the battery monomer is longer, which helps to reduce the volume ratio of the shell in the battery monomer and improve the load ratio of the active material. At the same time, the longer battery monomer can reduce the number of batteries required in the battery module, simplify the structural design of the battery module, and reduce the number and complexity of structural parts in the module, thereby improving the space utilization of the battery pack, and further helping to improve the volume energy density of the battery monomer.

[0073] In any embodiment, the material of the shell is a soft package material, which includes an aluminum plastic composite film, optionally, a composite film formed by one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), polyethylene (PE) and aluminum.

[0074] The soft package material has a high ductility, so that the shell is more lightweight, soft, and helps to improve the space utilization of the battery monomer, thereby improving the energy density of the battery monomer. In addition, the high barrier property of aluminum can effectively reduce the penetration of water and oxygen into the battery, reduce the decomposition of electrolyte and the oxidation degree of electrode material, thereby improving the service life of the battery.

[0075] In any embodiment, the shell includes a first sealing area, which is arranged at at least one end of the jelly-roll battery cell extending in the width direction; the first sealing area includes a folding edge structure extending in the length direction, and the folding edge structure is provided with encapsulation glue, which is continuously arranged and fixed to the folding edge structure in the length direction.

[0076] The folding edge structure extending in the length direction in the first sealing area further improves the sealing strength of the first sealing area. The continuous arrangement and fixation of the encapsulation glue to the folding edge structure in the length direction can further improve the encapsulation strength, realize continuous reinforcement in the length direction of the sealing area, and reduce the probability of the jelly-roll battery cell breaking the sealing area in the package during the cycle rebound process.

[0077] In any embodiment, the shell includes at least one second sealing area, which is arranged at at least one end of the jelly-roll battery cell extending in the length direction of the shell, and the second sealing area is arranged at the tab side of the jelly-roll battery cell.

[0078] The second sealing area is arranged at the tab side, and the tab needs to be connected with the lead-out piece. The connection strength between the lead-out piece and the shell material is relatively weak, so that gas is easily discharged from the second sealing area, which is conducive to realizing the directional pressure relief of the battery, reducing the influence on the adjacent battery cells during thermal runaway, and improving the service life of the whole battery.

[0079] In any embodiment, the jelly-roll battery cell is provided with a plurality of glue rings surrounding in the width direction, and the glue rings surrounding in the width direction are arranged at intervals in the length direction.

[0080] The interval arrangement of the glue rings surrounding in the width direction of the battery cell in the length direction is conducive to fixing the positions of the jelly-roll battery cells, reducing the probability of displacement of the battery cells during the shaking process of the battery, and is especially suitable for batteries with a large length. It can effectively reduce the mutual displacement of the jelly-roll battery cells in the length direction and thus cause lithium precipitation, and is conducive to maintaining the stability of the space structure inside the battery, so as to not affect the normal work of the battery.

[0081] In any embodiment, the capacity of the battery cell is 100 Ah-300 Ah, optionally 110 Ah-190 Ah, further optionally 125 Ah-180 Ah at 25℃.

[0082] The battery cell of the embodiment of the application has a high capacity by controlling the reasonable proportion of large particles in the film layer of the positive electrode sheet in the jelly-roll battery cell and by suitable shell size to accommodate the jelly-roll battery cell.

[0083] The second aspect of the application provides a battery device comprising the battery cell provided by the first aspect of the application.

[0084] The third aspect of the application provides a power consumption device, which comprises the battery device provided by the second aspect of the application, and the battery device is used to provide electric energy.

[0085] The fourth aspect of the application provides an energy storage device, which comprises the battery device provided by the second aspect of the application, and the battery device is used to store electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0086] Figure 1 is a schematic diagram of a separator of an embodiment of the application;

[0087] Figure 2 is a schematic diagram of a separator of the prior art;

[0088] Figure 3 is a schematic diagram of the surface morphology of the bonding layer of a separator of an embodiment of the application;

[0089] Figure 4 is a schematic diagram of a positive electrode sheet of an embodiment of the application;

[0090] Figure 5 is a front view of a battery cell of an embodiment of the application;

[0091] Figure 6 is a schematic diagram of a power consumption device of an embodiment of the application.

[0092] BRIEF DESCRIPTION OF DRAWINGS

[0093] 10 positive electrode sheet; 101 positive electrode current collector; 102 positive electrode film layer; 102a first surface; 102b second surface; 1021 first region; 20 separator; 201 base film; 202 ceramic layer; 203 bonding layer; 5 battery cell; 50 shell; 51 first sealing area; 52 second sealing area; 53 lead-out piece; X length direction; Y width direction; Z thickness direction. DETAILED DESCRIPTION

[0094] Below, the embodiments of the battery cells, battery devices, electrical devices, and energy storage devices of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0095] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0096] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0097] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0098] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned above can further comprise step (c), which means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0099] In the present application, the term "a plurality of" or "a plurality" means two or more.

[0100] Unless otherwise specified, the terms used in the present application have the commonly understood meanings by those skilled in the art.

[0101] Unless otherwise specified, the values of the parameters mentioned in the present application can be measured by various test methods commonly used in the art, for example, the test methods given in the examples of the present application. Unless otherwise specified, the test temperature of each parameter is 25°C.

[0102] In the examples of the present application, the battery device can comprise one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can comprise a plurality of soft-pack battery cells connected in series, in parallel or in a mixed connection by a busbar component. For example, the battery cell assembly is usually formed by arranging a plurality of soft-pack battery cells; the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of soft-pack battery cells into an independent module. As an example, the battery module can be formed by binding a plurality of battery cells by a cable tie.

[0103] The battery device can be a battery pack, which comprises a box body and one or more battery cell assemblies accommodated in the box body. The battery cell assembly can be a battery module, which can be accommodated in the box body by fixing the battery module in the box body; the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of soft-pack battery cells in the box body.

[0104] In the examples of the present application, the box body can comprise a first box body and a second box body. The first box body and the second box body are buckled to form a closed space inside the box body to accommodate the battery cell assembly. Here, closed means covered or closed, which can be sealed or unsealed. The first box body can be a top cover or a bottom plate. For example, the box body can comprise a top cover, a frame and a bottom plate. The top cover and the bottom plate are connected with the frame respectively, so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0105] In embodiments of the present application, the case can be part of the chassis structure of the vehicle. For example, portions of the case can be part of the floor of the vehicle, or portions of the case can be part of the cross members and the longitudinal members of the vehicle.

[0106] In embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be used continuously by activating the active material through charging after discharging the battery cell; the battery cell can be a lithium ion battery. The battery cell can be in the form of a flat body.

[0107] The battery referred to in embodiments of the present application can be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application can include a battery cell, a battery module, or a battery pack, etc.

[0108] The battery cell is the smallest unit that makes up the battery, and it alone can achieve the function of charging and discharging. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in a mixed connection through a busbar component. In some embodiments, the battery can be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery can be a battery pack, which includes a case and battery cells, and the battery cells or the battery module are housed in the case. In some embodiments, the case can be part of the chassis structure of the vehicle. For example, portions of the case can be part of the floor of the vehicle, or portions of the case can be part of the cross members and the longitudinal members of the vehicle.

[0109] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0110] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0111] The battery cell includes an electrode assembly and an electrolyte.

[0112] The electrode assembly generally includes a positive electrode sheet and a negative electrode sheet, the negative electrode sheet is an electrode that undergoes a reaction of absorbing or lithiating lithium ions during charging and releasing or delithiating lithium during discharging, and the positive electrode sheet is an electrode that undergoes a reaction of releasing or delithiating lithium ions during charging and absorbing or lithiating lithium during discharging.

[0113] Compared with lithium-containing transition metal oxide materials, lithium-containing transition metal phosphate materials have the advantages of high safety, long cycle life, low cost, stable high-temperature performance, etc. However, the specific capacity of lithium-containing transition metal phosphate materials is low, which is not conducive to the improvement of battery capacity. The applicant found that compared with the wound electrode, the laminated electrode does not have a corner area, has a higher utilization rate of the internal volume of the battery, and the use of the laminated electrode is beneficial to further improve the volume energy density of the battery. At the same time, a certain amount of large particles is beneficial to increase the gradation of the film layer and improve the compaction density of the electrode sheet, thereby further increasing the volume energy density of the battery. However, the laminated electrode has a higher capacity due to the absence of the corner area in the wound electrode, but it also lacks radial restraint force, resulting in weak interfacial shear force between the positive and negative electrode films and the separator, which is prone to relative sliding under long cycle or mechanical impact, increasing the risk of short circuit. At the same time, stress concentration is prone to occur in the large particles in the film layer during the compaction process of the electrode sheet, and the stress is gradually released during the cycle process, causing the film layer to rebound. In the case of lack of external restraint force in the laminated electrode, the film layer rebound is more likely to cause the misalignment between the positive and negative electrode sheets and the separator, further increasing the risk of local short circuit of the battery and deteriorating the cycle performance of the battery. How to obtain a battery with good capacity and cycle performance at the same time is a technical problem that needs to be solved in the field.

[0114] The first aspect of the present application provides a battery monomer, which comprises a laminated electrode, the laminated electrode comprising a positive electrode sheet, a negative electrode sheet, and a separator arranged between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprising lithium-containing transition metal phosphate particles, at least part of the surface of the lithium-containing transition metal phosphate particles being provided with a carbon material; in a section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of particles with a particle size greater than or equal to 1 μm is 12%-50%; wherein the structure of the separator is as shown in Figure 1 The first aspect of the present application provides a battery monomer, which comprises a laminated electrode, the laminated electrode comprising a positive electrode sheet, a negative electrode sheet, and a separator arranged between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprising lithium-containing transition metal phosphate particles, at least part of the surface of the lithium-containing transition metal phosphate particles being provided with a carbon material; in a section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of particles with a particle size greater than or equal to 1 μm is 12%-50%; wherein the structure of the separator is as shown in

[0115] The first aspect of the present application provides a battery monomer, which comprises a laminated electrode, the laminated electrode comprising a positive electrode sheet, a negative electrode sheet, and a separator arranged between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprising lithium-containing transition metal phosphate particles, at least part of the surface of the lithium-containing transition metal phosphate particles being provided with a carbon material; in a section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of particles with a particle size greater than or equal to 1 μm is 12%-50%; wherein the structure of the separator is as shown in

[0116] The embodiments of the present application improve the capacity of the battery by using the laminated cell with the lithium-containing transition metal phosphate positive electrode film layer containing a certain amount of large particles, further using the separator with ceramic layers on both sides to increase the stiffness of the separator, and using the separator with a porous structure of continuous layer with larger bonding area and stronger bonding force to increase the bonding effect of the separator and the positive electrode sheet, improve the compactness and stiffness of the laminated cell inside the group, make up for the deficiency of small external restraint force of the laminated cell, reduce the risk of mutual extrusion of the positive and negative electrode sheets in the thickness direction of the cell during the rebound process evolving into horizontal misplacement, reduce the risk of positive and negative electrode overlap and further short circuit, so that the battery further improves the cycle performance on the basis of good capacity.

[0117] In the present application, the laminated cell refers to the cell formed by stacking the positive electrode sheet, the separator and the negative electrode sheet together.

[0118] In the present application, the positive electrode film layer contains lithium-containing transition metal phosphate particles, but the positive electrode film layer does not simply refer to the positive active material layer, and other film layers connected with the positive active material layer and difficult to distinguish, such as primer layer, liquid retaining layer, etc. are collectively referred to as positive electrode film layer.

[0119] The lithium-containing transition metal phosphate refers to the phosphate material containing lithium element and transition metal element, which can be detected by any known method in the art. For example, it can be detected by X-ray diffractometer (XRD) and energy spectrum analyzer, inductively coupled plasma mass spectrometer.

[0120] In the present application, the term "particle" refers to the particle in the field of view of the positive electrode film layer under a certain magnification, for example 10 thousand times, with recognizable complete boundaries. There can be defects and scratches inside the particle, but the complete boundaries inside the particle cannot be recognized enough to divide the particle.

[0121] The particle recognition method is specifically as follows: the positive electrode film layer is cut along the thickness direction of the pole piece by an argon ion beam (as an example, the device model: Leica EM TIC 3X CP, working voltage: 6kV, working time: 6h can be selected), and the cut surface is observed by a scanning electron microscope (as an example, the device model: Hitachi SU8230, working voltage: 3kV, beam current: high, probe model: U (LA100), working distance < 5mm can be selected) after the cut surface is exposed. The cut surface of the positive electrode film layer along the thickness direction of the pole piece is observed by a field emission scanning electron microscope. The image is collected by a secondary electron mode at a non-edge position in the cut surface of the positive electrode film layer (after observing the edge of the pole piece under the scanning electron microscope, the field of view is adjusted to the center part of the sample), and the electron microscope image is taken at a magnification of 10k. The particles in the electron microscope image are analyzed by using ImageJ software (1.46r, win64 version). The use method of the ImageJ software is specifically as follows: the scanning electron microscope image to be analyzed is loaded; the Cellpose plug-in software is used to recognize the particles, and manual correction is performed on this basis; the Image J is used to read and count the data. The specific method of recognizing the particles by using the Cellpose plug-in software is as follows: the Segmantation module diameter parameter is set to 15 pixels, and the particle recognition is performed by clicking "runcyto3"; the particles in the image that are not recognized by the software or not completely recognized by the software or have errors in recognition are manually identified. The particles in the image that are not recognized by the software or not completely recognized by the software or have errors in recognition mainly include the following: 1, due to the fact that the particles are too large or the particles have scratches on the surface, the particles cannot be recognized or cannot be completely recognized; 2, during the cutting process of the argon ion beam, scratches will be generated on the surface of the particles, and the software may misjudge the scratches as the boundaries of the particles during the recognition process, thereby causing recognition errors; 3, due to the fact that the particles are too small, the particles are not successfully recognized; 4, the particles are located at the edge of the electron microscope field of view, the particles are penetrated by the edge, the morphology is not completely displayed, and the local instead of the whole is recognized, thereby causing recognition errors.For the above-mentioned unrecognizable or with recognition error particles, manual calibration is carried out, and the specific process is as follows: deleting the particles located at the edge of the scanning electron microscope, which cannot completely display the large particles; judging whether there is a gap mark in the interior of other unrecognizable or with recognition error particles, if there is no gap mark in the interior of the particles, judging that it is a particle, and manually marking it according to the particle boundary observed by manual observation; in response to the existence of the gap mark in the interior of the particle, judging whether the gap mark penetrates the particle, if not, judging that it is a particle, and manually marking it; in response to the gap mark penetrating the particle, judging whether the gap mark is linear or irregular; in response to the gap mark being irregular, judging that it is the boundary between particles, and dividing the particles along the boundary; in response to the gap mark being linear, carrying out contrast; in response to the contrast being not obvious and having no crack feeling, judging that it is a scratch, and marking it as a particle; in response to the contrast being strong and having crack feeling, judging that it is the boundary between particles, and marking it as two particles. After manual marking, the information irrelevant to the particles in the automatic processing of the image is deleted, that is, the determination and marking of the particles in the picture are completed.

[0122] The area proportion of the particles with a particle size greater than or equal to 1 μm in the section of the positive electrode film layer along the thickness direction of the pole piece can directly reflect the proportional relationship between the particles in this particle size section and the overall particle area, and reflect the area size of the particles in this particle size section.

[0123] It can be understood that the particles with a particle size greater than or equal to 50 nm in the section of the positive electrode film layer along the thickness direction of the pole piece are mainly derived from the positive electrode active material. Therefore, the distribution of the lithium-containing transition metal phosphate particles in the positive electrode film layer can be accurately and objectively reflected by observing and counting the particle area in the section of the positive electrode film layer along the thickness direction of the pole piece.

[0124] In the prior art, the particle size of the positive electrode active material is usually counted by a laser particle size analyzer through a Malvern laser diffraction method. However, the research of the applicant shows that the lithium-containing transition metal phosphate particles are easy to agglomerate, and the test results obtained by the Malvern laser diffraction method according to the laser scattering principle are often the particle sizes of the particle agglomerates, and cannot truly reflect the particle size of the particles in the positive electrode active material, and cannot reflect the dispersion state of the positive electrode active material in the film layer, because the dispersion degree of the positive electrode active material in the film layer will be improved in the processes of slurry preparation and film rolling. The test results obtained by the Malvern laser diffraction method are affected by the particle size, specific surface area and agglomeration degree of the positive electrode active material, and compared with the real dispersion in the pole piece, the number of large particles obtained by the test is lower than the actual value, and the number of small particles is higher than the actual value, so the particle size obtained by the Malvern laser diffraction method cannot be equal to or analogous to the particle size obtained by the counting of the embodiments of the application.

[0125] The area ratio of the particles with a particle size of 1 μm or more in the section of the positive electrode film layer along the thickness direction of the electrode tab is tested according to the following method. The particles in the section of the positive electrode film layer along the thickness direction of the electrode tab are identified according to the method described above, and the picture after the identification of the particles is imported into the ImageJ software for analysis. The scale is set according to the scanning electron microscope picture, and the particle size, area, sphericity and roughness of the particles in the section of the positive electrode film layer along the thickness direction of the electrode tab are statistically analyzed by using the analysis functions of “Feret”, “Area”, “Round” and “Solidity”. According to the software manual (ImageJ User Guide IJ 1.46r), the “Feret” parameter obtained by the analysis represents the maximum distance between all parallel lines in the two-dimensional projection of the particle, which represents the particle size of the particle; the “Area” parameter obtained represents the pixel area of the particle. Since the particles with a particle size of less than 50 nm have a large error in the statistical process and are difficult to accurately identify, and the particle size of the conductive agent is generally less than 50 nm, which will cause a large error in the statistical result, therefore, in the particle size statistical process of the present application, the particles with a particle size of less than 50 nm are not counted, and the particle statistical data corresponding to the particles with “NaN” displayed in Area, Round or Solidity are deleted. The sum of the “Area” parameters of the particles with a particle size of 1 μm or more and the sum of the “Area” parameters of all the particles are calculated as the area of the particles with a particle size of 1 μm or more and the total area of the counted particles, respectively. The area ratio of the particles with a particle size of 1 μm or more in the section of the positive electrode film layer along the thickness direction of the electrode tab is calculated by dividing the sum of the areas of the particles with a particle size of 1 μm or more by the total area of the counted particles.

[0126] In some embodiments, the area ratio of the particles with a particle size of 1 μm or more in the section of the positive electrode film layer along the thickness direction of the electrode tab can be 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 numerical range between any two of them.

[0127] In some embodiments, the vinylidene fluoride polymer includes one or more of a vinylidene fluoride homopolymer (PVDF) and a copolymer of vinylidene fluoride and hexafluoropropylene.

[0128] As Figure 2As shown, in the prior art, aqueous PVDF is often used as the bonding layer of the diaphragm, which often presents an island structure in the diaphragm. On the one hand, this is beneficial for providing gaps for the expansion of the battery cell and on the other hand, it is easy to manufacture; however, the bonding area of ​​such a diaphragm bonding layer is low and the bonding force is weak.

[0129] like Figure 3 The figure shows a schematic diagram of the surface morphology of the bonding layer 203 of the diaphragm of the embodiment of the present application. The bonding layer of the diaphragm of the embodiment of the present application has a certain pore structure in its continuous structure. The ceramic layer disposed between the base film and the bonding layer can be observed through the pore structure. It can be understood that when a continuous layer with a porous structure is used as the bonding layer, it may become lumpy due to contact with the positive electrode sheet or the negative electrode sheet or pressure compression during the electrode manufacturing or circulation process. The continuous layer referred to in this application does not require that the bonding layer is continuous throughout the entire battery; rather, it refers to a continuous layer with a uniform porous structure at the microscopic level, such as when observed under a microscope, rather than an island structure. In order to reflect the true morphology of the diaphragm, during the sampling process, it is preferred to sample in the area of ​​the battery where the diaphragm bonding layer has little adhesion to the positive electrode sheet or the negative electrode sheet. As an example, sampling is performed at the diaphragm position where the projection exceeds the positive electrode sheet and the negative electrode sheet; or sampling is performed at the diaphragm near the surface of the electrode assembly. The diaphragm sampled in this way can better reflect the true state of the diaphragm.

[0130] The diaphragm provided in the embodiment of the present application uses a continuous layer of 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 bonding between the diaphragm and the positive electrode film layer more firm and uniform. At the same time, with the help of the pore structure in the bonding layer, it can have both the transmission efficiency of lithium ions and the dynamic performance of the battery. Compared with wound cells, the pressing force between the pole pieces in the cell preparation process of laminated cells is small. Lithium-containing transition metal phosphate particles with a particle size greater than or equal to 1 μm will damage the SEI film and the pole piece film layer during the rebound process. At the same time, the mutual extrusion of the positive and negative pole pieces in the thickness direction can easily cause relative dislocation of the positive and negative pole pieces in the horizontal direction. The diaphragm provided in the embodiment of the present application is provided with a ceramic layer on both sides, and uses a continuous layer of a porous structure as a bonding layer. It is particularly suitable for laminated cells, which is beneficial to reduce the rebound phenomenon of laminated cells during long cycles and improve the maintenance of battery capacity during long cycles.

[0131] The embodiment of the present application uses a continuous layer of a porous structure as a bonding layer to improve the bonding force between the diaphragm and the electrode while maintaining the air permeability and porosity of the diaphragm, thereby improving the stability of the electrode, further reducing the risk of internal short circuit caused by electrode rebound, and improving the cycle stability of the battery.

[0132] In some embodiments, the material of the base film may include, but is not limited to, one or more of glass fiber, non-woven fabric, polyethylene (PE), and polypropylene (PP).

[0133] In the present application, the ceramic layer includes ceramic particles, and the ceramic particles include one or more of Al2O3, AlO(OH), SiO2, TiO2, MgO, CaO, ZnO2, ZrO2, and SnO2.

[0134] Ceramic particles are flame-retardant and have a high hardness, resisting deformation under heat and resulting in excellent dimensional stability. The ceramic layers on both sides of the base film help increase battery rigidity, reduce electrode rebound, and minimize the likelihood of contact between the negative and positive electrode films during electrode rebound, leading to short circuits.

[0135] In some embodiments, in a cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​particles with a particle size of 1 μm-5 μm accounts for 12%-50%.

[0136] The area ratio of particles with a particle size of 1μm-5μm in the cross-section of the positive electrode film layer along the thickness direction of the electrode is within the above range, which is beneficial for the battery to improve the rebound phenomenon of large particles in the electrode during the battery cycle while maintaining high capacity, thereby improving the battery's cycle performance.

[0137] In some embodiments, in a cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​particles with a particle size of 1 μm-5 μm accounts for 12%-40%.

[0138] The area ratio of particles with a particle size of 1μm-5μm in the cross-section of the positive electrode film layer along the thickness direction of the electrode is within the above range, which is beneficial for the battery to further improve the electrode rebound phenomenon caused by stress concentration caused by large particles in the electrode while maintaining high capacity, reduce the probability of contact between the negative electrode film layer and the positive electrode film layer and short circuit, and further improve the cycle performance of the battery.

[0139] In some embodiments, the thickness of a single side of the positive electrode film layer is 70 μm-120 μm.

[0140] like Figure 4 As shown, the thickness H of the positive electrode film layer on one side refers to the distance from the first surface 102a of the positive electrode film layer 102, which is away from the positive electrode current collector 101, to the second surface 102b disposed opposite the first surface 102a. It should be noted that the positive electrode film layer contains lithium-containing transition metal phosphate particles, but the positive electrode film layer does not refer solely to the positive electrode active material layer. Other film layers connected to the positive electrode active material layer and difficult to distinguish, such as the primer layer and the liquid retention layer, are collectively referred to as the positive electrode film layer.

[0141] The thickness of the positive electrode film can be measured by any method known in the art. As an example, the thickness of the positive electrode film is measured along the thickness direction of a cross section of the positive electrode sheet using a scanning electron microscope. Measurements are taken at three randomly selected locations, and the average value is calculated as the thickness of the positive electrode film.

[0142] In some embodiments, the single-side thickness of the positive electrode film layer can be selected from 70 pm, 72.34 pm, 71 pm, 72 pm, 73 pm, 74 pm, 75 pm, 76 pm, 77 pm, 78 pm, 79 pm, 80 pm, 81 pm, 82 pm, 83 pm, 83.91 pm, 84 pm, 85 pm, 86 pm, 87 pm, 88 pm, 89 pm, 90 pm, 91 pm, 91.88 pm, 92 pm, 93 pm, 94 pm, 95 pm, 96 pm, 97 pm, 98 pm, 98.93 pm, 99 pm, 100 pm, 101 pm, 102 pm, 103 pm, 104 pm, 105 pm, 105.44 pm, 105.64 pm, 105.65 pm, 105.89 pm, 106 pm, 106.21 pm, 106.34 pm, 107 pm, 108 pm, 109 pm, 110 pm, 111 pm, 112 pm, 113 pm, 114 pm, 115 pm, 116 pm, 116.09 pm, 117 pm, 118 pm, 119 pm, 120 pm, or a range of values between any two of them.

[0143] The specific capacity of the lithium-containing transition metal phosphate particles is relatively low, and research shows that when the single-side thickness of the positive electrode film layer is less than 70 pm, the capacity of the battery is difficult to meet market demand. The single-side thickness of the positive electrode film layer in the above range is beneficial to improve the capacity of the battery monomer.

[0144] In some embodiments, the single-side thickness of the positive electrode film layer is 90 pm-120 pm.

[0145] The single-side thickness of the positive electrode film layer in the above range is beneficial to further improve the battery capacity.

[0146] In some embodiments, the single-side thickness of the positive electrode film layer is 100 pm-120 pm.

[0147] Increasing the single-side thickness of the positive electrode film layer is beneficial to improve the capacity of the battery. The applicant found that when the single-side thickness of the positive electrode film layer is greater than or equal to 100 pm, the phenomenon of particle rebound in the positive electrode film layer is more serious. The embodiments of the present application effectively alleviate the serious rebound of the thick coated film layer in the laminated battery cell, and the battery has improved cycle performance on the basis of maintaining high capacity.

[0148] In some embodiments, as Figure 4As shown, the positive electrode tab 10 includes a positive electrode current collector 101 and a positive electrode film layer 102 disposed on at least one side of the positive electrode current collector 101, and the positive electrode film layer 102 includes a first region 1021 located at the top of the positive electrode film layer 102 away from the positive electrode current collector 101, and the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region 1021 is 0.2%-5%, which can be 0.2%-3.5%.

[0149] In this application, the first region of the positive electrode film layer refers to the region located at the top of the positive electrode film layer away from the current collector. As an example, the region within the thickness range of 20 μm from the first surface 102a of the positive electrode film layer is recorded as the first region of the positive electrode film layer.

[0150] The test method for the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region can be tested by methods known in the art. As an example, the cross-sectional view of the positive electrode film layer along the thickness direction is obtained, and the cross section of the first region of the positive electrode film layer is observed by scanning electron microscopy at 3k magnification by using the similar method described above, and the 3k electron microscope image is continuously observed at 10k magnification, 10 non-overlapping fields are selected, and 10 scanning electron microscope images are taken; the 10 scanning electron microscope images taken are respectively imported into ImageJ software for analysis, and the area ratio of particles with a particle size greater than or equal to 1 μm in the 10 images is tested to obtain 10 values; the range of the 10 values is the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region, wherein the range is the difference between the maximum and minimum values of the 10 values. The smaller the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region, the more uniform the distribution of large particles in the positive electrode film layer.

[0151] In some embodiments, the distribution uniformity of particles with a particle size greater than or equal to 1 μm in the first region can be 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 numerical range between any two of them.

[0152] The stress concentration levels at large and small particles in the positive electrode film differ, and as the stress gradually releases during cycling, the electrode sheet experiences varying degrees of rebound. The embodiments of this application contain a certain amount of large particles, and these large particles are evenly distributed throughout the electrode sheet, resulting in a uniform distribution of the compressive force of the positive electrode film on the diaphragm. This reduces the risk of localized excessive compression and blockage of lithium ion transmission pathways due to uneven distribution of large particles, leading to increased peripheral current density and increased lithium deposition. This improves the battery's cycling performance while maintaining good capacity.

[0153] In some embodiments, in the cross section of the positive electrode film along the thickness direction of the electrode, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size greater than or equal to 1 μm, the median of the sphericity L A50 It is 0.6-0.8.

[0154] The specific method for testing the sphericity of particles with a particle size greater than or equal to 1 μm in the cross-section of the positive electrode film layer along the thickness direction of the electrode is as follows: refer to the method described above in this application to identify particles with a particle size greater than or equal to 1 μm in the cross-section of the positive electrode film layer along the thickness direction of the electrode, and use the "Shape Description" analysis function in ImageJ to analyze the morphology of the particles in the cross-section of the positive electrode film layer along the thickness direction of the electrode. According to the software manual (ImageJ User Guide IJ 1.46r), the "Round" parameter obtained by analysis represents the ratio of the pixel area of ​​the particle to the area of ​​the circle with the fitted long diameter as the diameter, which can be used to characterize the sphericity of the particle. The closer the particle is to a sphere, the closer the ratio of the pixel area to the area of ​​the circle with the fitted long diameter as the diameter is to 1. Therefore, the "Round" parameter of the particle obtained by analysis is used to characterize the sphericity of the particle. Since particles with a diameter of less than 50 nm have large errors in the statistical process and are difficult to identify accurately, and the particle size of the conductive agent is generally less than 50 nm, it will cause large errors in the statistical results. Therefore, in the particle size statistical process of this application, particles with a diameter of less than 50 nm are not counted, and the statistical data of particles displayed as "NaN" are deleted. According to the above method, in order to meet the number of samples with statistical significance, each electrode is collected with no less than 10 scanning electron microscope images with non-overlapping fields of view. The sphericity of at least 1000 particles obtained is arranged in order from small to large, and the sphericity is used as the horizontal axis and the cumulative area ratio is used as the vertical axis to obtain the cumulative distribution curve of the sphericity of the particles in the positive electrode film layer. L A50 It is the sphericity L value corresponding to when the cumulative area of ​​the vertical axis in the cumulative distribution curve of the particle sphericity L value accounts for 50%.

[0155] In some embodiments, in the cross section of the positive electrode film along the thickness direction of the electrode, in the cumulative distribution curve of the sphericity area of ​​particles with a particle size greater than or equal to 1 μm, the median of the sphericity L A50Optionally 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 numerical range between any two of them.

[0156] The median of the sphericity of the particles with a particle size greater than or equal to 1 μm is in the above range, and the large particles have better sphericity, reducing particle bridging caused by irregular shapes of large particles, reducing the void content in the pole piece, and at the same time reducing stress concentration caused by irregular large particles, reducing the rebound of the pole piece caused by stress release during the cycle process, so that the battery monomer has high capacity while further improving its cycle performance.

[0157] The skilled person can realize the regulation of the sphericity of the particles by any process known. As an example, the regulation of the sphericity of the particles can be realized by processes such as grinding, polishing, chemical etching, mechanical stirring, extrusion, coating, granulation, adding surfactants, etc., and adjusting the parameters of each process.

[0158] In some embodiments, in the section of the positive electrode film layer along the thickness direction of the pole piece, in the sphericity area cumulative distribution curve of the particles with a particle size greater than or equal to 1 μm, the median of the sphericity L A50 is 0.65-0.75.

[0159] The median of the sphericity of the particles with a particle size greater than or equal to 1 μm is in the above range, which is beneficial to reduce the stress concentration of large particles caused by irregular large particles, reduce the rebound of the pole piece caused by stress release during the cycle process, and improve the cycle performance of the battery.

[0160] In some embodiments, in the section of the positive electrode film layer along the thickness direction of the pole piece, in the sphericity area cumulative distribution curve of the particles with a particle size greater than or equal to 1 μm, the median of the sphericity L A50 is 0.67-0.75.

[0161] The median of the sphericity of the particles with a particle size greater than or equal to 1 μm is in the above range, which is beneficial to reduce the stress concentration of large particles caused by irregular large particles, reduce the rebound of the pole piece caused by stress release during the cycle process, and improve the cycle performance of the battery.

[0162] In some embodiments, in the cumulative distribution curve of the graphitization degree C value obtained by the positive electrode film layer under the face scanning mode of the laser microscopic confocal Raman spectrometer, the median of the graphitization degree C 50 is greater than or equal to 0.95 and less than or equal to 1.20; wherein the graphitization degree C value is I G / I D , IG I G represents the intensity of the G peak of the Raman spectrum at 1580±100 cm -1 D I D represents the intensity of the D peak of the Raman spectrum at 1350±100 cm -1

[0163] In the present application, the graphitization degree C value of the positive electrode film layer can be obtained by a laser microscopic confocal Raman spectrometer in a surface scanning mode. As an example, specifically, a laser microscopic confocal Raman spectrometer (high-precision Renishaw laser microscopic confocal Raman spectrometer) is used, an excitation wavelength of 532 nm is selected, an appropriate amount of positive electrode film layer is taken, and the surface thereof or the section thereof along the thickness direction of the electrode sheet is surface-scanned, the scanning area is 45 μm x 45 μm, it is divided into 10 x 10 grids, the grid vertices are taken as test points, the step length is 5 μm, and the total number of scanning points is 100 points, thereby obtaining the C values of different sites and the C value cumulative distribution curve of the surface scanning area.

[0164] The positive electrode film layer in the present application can be a freshly prepared positive electrode film layer or a positive electrode film layer obtained by disassembling a battery. The surface of the positive electrode film layer obtained by disassembling a battery inevitably has residual electrolyte salt particles. In order to improve the testing accuracy, the section of the positive electrode film layer along the thickness direction of the electrode sheet is preferably surface-scanned to characterize the graphitization degree of the positive electrode film layer.

[0165] The graphitization degree C value of the positive electrode film layer is obtained by the peak intensity ratio of the G peak (G-band) and the D peak (D-band) of the Raman spectrum, the G peak position is 1580±100 cm -1 , which represents the sp 2 hybrid structure of carbon; and the D peak position is 1350±100 cm -1 , which represents the disordered structure of carbon, wherein the disorder represents that there is no regular arrangement mode between carbon atoms in the structure.

[0166] The graphitization degree C value cumulative distribution curve refers to a curve obtained by arranging at least 100 C values in ascending order, taking the graphitization degree as the horizontal axis, and taking the cumulative number ratio as the vertical axis. C 50 The median C value of the graphitization degree is the C value corresponding to the cumulative number ratio of 50% on the vertical axis of the graphitization degree C value cumulative distribution curve. The median C value of the graphitization degree 50 compared to the point value, it can reflect the graphitization degree of the particles as a whole in the positive electrode film layer, i.e., the easy sliding degree; compared to the mean value, it can reduce the influence of extreme values in the testing process and improve the confidence of the testing result.

[0167] ​​The skilled person can control the graphitization degree of the active material particles by any process known in the art. As an example, the carbon source, sintering temperature, sintering time, sintering pressure, sintering atmosphere can be adjusted to control the graphitization degree of the active material particles.

[0168] In some embodiments, the median value C of the graphitization degree in the cumulative distribution curve of the graphitization degree C value obtained by the cathode film layer under the laser microscopic confocal Raman spectrometer face scanning mode is 0.30-0.60. 50 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 numerical range between any two of them.

[0169] The median value C of the graphitization degree in the cumulative distribution curve of the graphitization degree C value obtained by the cathode film layer under the laser microscopic confocal Raman spectrometer face scanning mode is 0.30-0.60. 50 The compaction density of the electrode sheet can be further improved within the above range, so that the content of large-size particles in the cathode film layer can be reduced, which helps to reduce the rebound phenomenon of the film layer caused by excessive large particles on the basis of maintaining the battery capacity, and further improve the cycle performance of the battery.

[0170] In some embodiments, the median value B of the coating value in the cumulative distribution curve of the coating value B obtained by the cathode film layer under the laser microscopic confocal Raman spectrometer face scanning mode is 0.30-0.60. 50 The coating value B is I P / I D , wherein I P represents the P peak intensity of the Raman spectrum at 948±100 cm -1 , I D represents the D peak intensity of the Raman spectrum at 1350±100 cm -1 .

[0171] The cumulative distribution curve of the coating value B value refers to arranging at least 100 obtained B values in order from small to large, obtaining a curve with the coating value as the horizontal axis and the cumulative number ratio as the vertical axis. In order to reduce the influence of the extreme value of the coating value caused by the non-particle area in the cathode film layer on the test results, the median value B 50 The compactness of the carbon material layer on the cathode active material is evaluated. B 50 The coating value B is the B value corresponding to the cumulative number ratio of 50% on the vertical axis of the cumulative distribution curve of the coating value B value.

[0172] In the present application, the coating value B of the positive electrode film layer can be obtained by laser microscopic confocal Raman spectroscopy scanning. As an example, specifically, a laser microscopic confocal Raman spectrometer (high-precision Renishaw laser microscopic confocal Raman spectrometer) is used, an excitation wavelength of 532 nm is selected, an appropriate amount of positive electrode film layer is taken, and the surface thereof or the section thereof along the thickness direction of the electrode sheet is scanned. The scanning area is 45 μm x 45 μm, which is divided into 10 x 10 grids, the grid vertices are taken as the test points, the step is 5 μm, and the total number of scanning points is 100 points. Thus, the B values of different sites and the B value cumulative distribution curve of the scanning area are obtained. The positive electrode film layer in the present application can be a freshly prepared positive electrode film layer or a positive electrode film layer obtained by disassembling a battery. The surface of the positive electrode film layer obtained by disassembling a battery inevitably has residual electrolyte salt particles. In order to improve the testing accuracy, the section of the positive electrode film layer along the thickness direction of the electrode sheet is preferably scanned to characterize the coating value of the positive electrode film layer.

[0173] The coating value B of the positive electrode film layer is obtained by the peak intensity ratio of the P peak (P-band) and the D peak (D-band) of the Raman spectrum. The P peak position is 948 ± 100 cm -1 , which represents the phosphate PO4 3- structure. The D peak position is 1350 ± 100 cm -1 , which is one of the characteristic peaks of carbon materials, and represents the sp 2 hybrid carbon atom lattice defects or disordered structure. In the test process, the excitation wavelength of 532 nm is selected, and the test depth is shallow, only the surface of the particles. Therefore, in the test results obtained by the laser microscopic confocal Raman spectroscopy scanning mode of the positive electrode film layer, the carbon structure peak exhibits a higher intensity than the phosphate structure peak.

[0174] A person skilled in the art can realize the regulation of the coating value of the active material particles by any known process. As an example, regulating the type of carbon source, the addition amount of carbon source, the sintering temperature, the sintering time, the sintering pressure, and the sintering atmosphere can all realize the adjustment of the coating value of the active material particles. The coating value B can reflect the density of the carbon material layer on the surface of the lithium-containing transition metal phosphate particles. The more dense the carbon material layer, the lower the intensity of the phosphate structure detected in the Raman spectrum, and the smaller the coating value B of the positive electrode film layer.

[0175] In some embodiments, the positive electrode film layer further comprises a coating layer arranged on at least part of the surface of the lithium-containing transition metal phosphate particles. In the cumulative distribution curve of the coating value B obtained by the laser microscopic confocal Raman spectroscopy scanning mode of the positive electrode film layer, the median of the coating value B 50Optionally 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.355, 0.36, 0.368, 0.369, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.446, 0.45, 0.456, 0.46, 0.47, 0.48, 0.49, 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6 or any numerical range between any two of them.

[0176] Median value B of the coating value of the positive electrode film layer 50 Within the above range, the carbon material layer of the positive electrode active material is more dense and uniform, which is beneficial to improve the uniformity of the positive electrode film layer in the rolling process and reduce the stress concentration phenomenon in the positive electrode film layer. In addition, with the help of the dense and uniform carbon material layer, the large particles in the positive electrode film layer are more likely to slip during the compaction process, thereby reducing the stress concentration phenomenon at the large particles in the positive electrode film layer, reducing the rebound caused by the release of stress at the large particles during the cycle process, and improving the cycle life of the battery.

[0177] In some embodiments, the iron leaching rate of the positive electrode material is 658 ppm-1921 ppm.

[0178] The iron leaching rate of the positive electrode material can be tested by a method known in the art. As an example, 7.5 g of positive electrode material powder obtained by scraping the powder from the positive electrode film layer sample is weighed and added to 100.3 g of ascorbic acid solution with a mass concentration of 0.3% (solvent is ultrapure water). After stirring at a speed of 500 revolutions per minute for 305 minutes, the solution is quickly sucked using a 5 mL syringe, filtered into a test tube using a 0.45 μm pore size filter head, and the supernatant is sucked 1 mL using a pipette, added to a glass volumetric flask and diluted 50 times. The iron element concentration in the solution is tested by inductively coupled plasma mass spectrometry (ICP-OES), and the iron leaching rate of the positive electrode material is calculated by the formula: (ICP test iron element concentration x solution volume / involved constant volume solution mass) x 100.3 g / positive electrode material powder mass, the solution volume is 50 mL, the involved constant volume solution mass is 1 g.

[0179] In some embodiments, the iron elution rate of the cathode material can be 658 ppm, 700 ppm, 800 ppm, 890 pm, 900 ppm, 1000 ppm, 1058 pm, 1076 pm, 1100 ppm, 1143 pm, 1200 ppm, 1236 pm, 1300 ppm, 1311 pm, 1384 pm, 1349 pm, 1400 ppm, 1485 pm, 1500 ppm, 1531 pm, 1600 ppm, 1700 ppm, 1800 ppm, 1921 ppm, or any numerical range between any two of the foregoing values.

[0180] In some embodiments, the iron elution rate of the cathode material is 658 ppm-1485 ppm.

[0181] The iron element eluted in the cathode material mainly comes from the lithium-containing transition metal phosphate particles of the cathode active material. The iron elution rate depends on the number of lattice defects of the lithium-containing transition metal phosphate particles and the completeness and density of the carbon material layer on the surface of the cathode active material. The lower the iron elution rate means that the lithium-containing transition metal phosphate particles have fewer lattice defects, which is beneficial to reducing the corrosion of the lattice in a weak acid environment; and the more complete and dense the carbon material layer on the surface of the cathode active material, the more the elution of iron ions in a weak acid environment is inhibited. The cathode material with an iron elution rate in the above range has relatively few lattice defects and a complete and dense carbon material layer, which is beneficial to improving the pressure resistance and easy sliding degree of the particles in the cathode film layer under large roller pressure, improving the compaction density of the cathode film layer and reducing the stress concentration in the cathode film layer, improving the rebound phenomenon of large particles due to stress concentration, so that the battery further improves the cycle performance on the basis of good capacity.

[0182] In some embodiments, the lithium-containing transition metal phosphate particles in the cathode film layer include components represented by the following general formula:

[0183] Li m Fe x P y O j Q q Formula I,

[0184] wherein Q includes 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, 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, 0≤q≤0.1.

[0185] In some embodiments, m can be selected from 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 range therebetween; x can be selected from 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, or any range therebetween. ; y can be selected as 0.95, 0.96, 0.97, 0.98, 0.99, 1.00 or any numerical range therebetween; j can be selected as 3.5, 3.6, 3.7, 3.8, 3.9, 4 or any numerical range therebetween; q can be selected as 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or any numerical range therebetween.

[0186] In some embodiments, the lithium-containing transition metal phosphate particles in the positive electrode film layer include one or more of lithium iron phosphate, lithium manganese phosphate, lithium fluorovanadium phosphate, lithium manganese iron phosphate, and modified materials thereof.

[0187] In some embodiments, the lithium-containing transition metal phosphate particles in the positive electrode film layer include one or more of lithium iron phosphate and its doping modification materials and coating modification materials.

[0188] In some embodiments, the mass content of titanium element is 500 ppm-8000 ppm based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0189] In some embodiments, the mass content of titanium element is 1000 ppm-3000 ppm based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0190] The type and content of elements in the lithium-containing transition metal phosphate particles in the positive electrode film can be tested by any method known in the art. As an example, titanium element and content are tested using inductively coupled plasma optical emission spectrometry in accordance with Appendix C of GB / T 33822-2017.

[0191] In some embodiments, the mass content of titanium element can be selected from 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, 2100 ppm, 2200 ppm, 2300 ppm, 2400 ppm, 2500 ppm, 2600 ppm, 2700 ppm, 2800 ppm, 2900 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 numerical range between any two of them, based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0192] The introduction of titanium element in the lithium-containing transition metal phosphate particles requires the addition of a titanium source in the preparation process of the positive electrode active material. The titanium source is often an inert material, which can reduce the reactivity of the raw materials of the lithium-containing transition metal phosphate particles and reduce the growth of the particle size. Higher sintering temperature or longer sintering time is often required to improve the graphitization degree of the positive electrode active material, but this will also increase the size of the particles in the positive electrode film layer, increase the stress concentration of the positive electrode film layer, and increase the rebound of the electrode tab during the cycle process. In the embodiments of the present application, by adding a high content of titanium element in the lithium-containing transition metal phosphate particles, the reactivity of the raw materials of the positive electrode active material is reduced, and the positive electrode active material is synthesized to have a high graphitization degree while controlling the proportion of large particles, reducing the stress concentration of the positive electrode film layer, improving the rebound phenomenon caused by stress concentration at large particles, and further improving the cycle performance of the battery on the basis of good capacity.

[0193] At the same time, the doping of titanium element in the positive electrode active material is beneficial to cause lattice distortion, reduce Li-O bond energy, improve lithium ion transmission rate, and improve the kinetic performance of the battery. The non-uniform diffusion of lithium ions in the positive electrode film layer is often accompanied by a significant lithium ion concentration gradient. The embodiments of the present application improve the solid-phase transmission rate of the positive electrode active material by adding a high content of titanium element in the lithium-containing transition metal phosphate particles, and improve the kinetic problems of the battery.

[0194] In some embodiments, the mass content of vanadium element is 500 ppm - 5000 ppm, based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0195] The type and content of elements in the lithium-containing transition metal phosphate particles in the positive electrode film layer can be tested by any publicly known method in the art. As an example, the content of vanadium element is tested by inductively coupled plasma atomic emission spectrometry according to Appendix C of GB / T 33822-2017.

[0196] In some embodiments, the mass content of vanadium element is selected from 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, 2100 ppm, 2200 ppm, 2300 ppm, 2400 ppm, 2500 ppm, 2600 ppm, 2700 ppm, 2800 ppm, 2900 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0197] In some embodiments, the mass content of vanadium element is 500 ppm - 3000 ppm, based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer.

[0198] The vanadium element in the positive electrode film layer can be in multiple valence states, wherein the vanadium in +5 valence (V 5+ ) can be doped at the phosphorus element site, which can cause lattice distortion due to its large radius, expand the diffusion channel of lithium ions, thereby improving the ionic conductivity of the positive electrode active material and the kinetic performance of the battery; the vanadium in +3 valence (V 3+ ) can be doped at the transition metal site to generate lithium vacancies through charge compensation, thereby improving the electronic conductivity of the positive electrode active material. In addition, the uniformity of the distribution of vanadium element in the lithium-containing transition metal phosphate particles is improved, which helps to further improve the kinetic performance of the positive electrode film layer and the reaction uniformity of the positive electrode film layer, thereby further improving the kinetic performance and cycle performance of the battery cell.

[0199] The mass content of vanadium element in the above range helps to improve the kinetic performance of the positive electrode sheet and the kinetic performance of the lithium-containing transition metal phosphate battery. At the same time, the titanium element, vanadium element and carbon nanotubes in the positive electrode film layer synergistically work together to help form a good three-dimensional network, further improving the electronic conductivity and ionic conductivity of the positive electrode film layer, thereby further improving the kinetic performance of the lithium-containing transition metal phosphate battery.

[0200] In some embodiments, the positive electrode film layer further includes a conductive agent. Based on the total area of ​​the cross section of the positive electrode film layer along the thickness direction of the electrode sheet, the total area of ​​the agglomerated region of the conductive agent accounts for 0.2%-6%, and can be optionally 1.5%-5%.

[0201] Based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode, the total area ratio of the agglomerated region of the conductive agent is within the above range, indicating that the conductive agent is evenly dispersed in the positive electrode film layer and is easy to form a uniform conductive network, which is beneficial to reduce the local polarization and even lithium plating problems generated by the battery during the cycle process.

[0202] At the same time, studies have shown that large-sized particles in lithium-containing transition metal phosphates are prone to rebound. The agglomeration area of ​​the conductive agent within the above range can suppress the rebound of lithium-containing transition metal phosphate particles with the help of the uniform distribution of the conductive agent, form mechanical constraints on the particles and even the film layer, improve the cohesion of the film layer, reduce the damage of the SEI film and the film layer during the rebound of the film layer, and improve the cycle life of the battery.

[0203] Based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode, the area ratio of the agglomerated region of the conductive agent can be tested by the following method. A similar method as described above is used to observe the cross-section of the positive electrode film layer along the thickness direction of the electrode through a scanning electron microscope, and the area of ​​the conductive agent agglomerated region in the scanning electron microscope image is measured at a magnification of 3k times. Since the conductive agent is generally a carbon-based material, such as conductive carbon black, carbon nanotubes, etc., the conductive agent agglomerated region often appears black agglomerated compared to other areas in the positive electrode film layer. At high magnifications, the aggregated conductive agent can be seen. The conductive agent agglomerated region refers to the black area range in the scanning electron microscope image where the conductive agent is obviously aggregated. Using image analysis software, such as the white-marked area in the ImageJ statistical chart, select areas where Feret values ​​are greater than or equal to 2 μm. The "Feret" parameter obtained from the analysis represents the maximum spacing between all parallel lines in the two-dimensional projection of this area. The total area is the total area of ​​the conductive agent agglomeration region in the scanning electron microscope image. The area ratio of the conductive agent agglomeration region is characterized by dividing the total area of ​​the conductive agent agglomeration region obtained by testing the scanning electron microscope image at 3k times magnification by the area of ​​the scanning electron microscope image. Randomly select three non-overlapping scanning electron microscope images and calculate the average value to be used as the "total area ratio of the conductive agent agglomeration region based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode sheet."

[0204] In some embodiments, the conductive agent includes carbon nanotubes, and the carbon nanotubes include one or more of single-walled carbon nanotubes, few-walled carbon nanotubes, and multi-walled carbon nanotubes. Optionally, the conductive agent further includes conductive carbon black.

[0205] The carbon nanotubes have a high aspect ratio, which is conducive to bridging multiple positive electrode particles in the thickness direction, forming a long-range conductive path while increasing the binding force between the particles, reducing local polarization and even lithium precipitation problems generated during the battery cycle process, and improving the cycle life of the battery; and can also reduce the rebound phenomenon of large particles in the positive electrode film layer through the binding effect, and improve the cycle performance of the battery.

[0206] The conductive carbon black has a small size, adheres to the surface of the positive electrode particles and fills the gaps between the positive electrode particles, forming a dense point-like conductive contact. In combination with the carbon nanotubes, both long-range and short-range conduction is considered, which is conducive to further improving the conductive network in the positive electrode film layer. At the same time, the conductive agent has a large specific surface area, which is conducive to liquid absorption and retention, can reduce the electrolyte extrusion phenomenon caused by the high growth rate of the expansion force of the electrode sheet during long cycle, and improve the long cycle life of the battery.

[0207] In some embodiments, the agglomeration region of the conductive agent includes carbon nanotubes and conductive carbon black.

[0208] Researchers found that carbon nanotubes are prone to agglomeration due to their high surface energy, resulting in uneven distribution in the positive electrode film layer and the inability to form an effective carbon nanotube network structure. The surface energy of the conductive carbon black and the carbon nanotube is relatively close, which can be adsorbed on the surface of the carbon nanotube to form a physical barrier, increase the resistance of carbon nanotube agglomeration, reduce direct contact between carbon nanotubes, and thus inhibit the agglomeration phenomenon, improve the uniformity of carbon nanotubes in the positive electrode film layer. On the one hand, this helps to improve the conductivity of the positive electrode film layer and improve the dynamic performance of the battery; on the other hand, it helps to exert the binding effect of carbon nanotubes on the positive electrode film layer, reduces the risk of positive electrode film layer falling off, and further improves the dynamic performance and cycle life of the battery. In addition, the agglomeration of carbon nanotubes in the conductive agent agglomeration region will also cause the blockage of the local ion transport path in the conductive agent agglomeration region, and the combination of conductive carbon black can improve the lithium ion transport capacity of this region, reduce local polarization, and further improve the cycle stability of the battery.

[0209] In some embodiments, the mass content C1 of the carbon nanotubes satisfies: 0 < C1 ≤ 2.5%, and the mass content C2 of the conductive carbon black satisfies: 0 < C1 ≤ 2.5%, based on the mass of the positive electrode film layer.

[0210] In some embodiments, the mass content C1 of the carbon nanotubes can be selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, or any numerical range between any two of them, based on the mass of the positive electrode film layer.

[0211] In some embodiments, based on the mass of the positive electrode film layer, the mass content C2 of the conductive carbon black can be selected as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or any numerical range therebetween.

[0212] When the mass content of carbon nanotubes and conductive carbon black is within the above range, the agglomeration of carbon nanotubes can be effectively alleviated and a good conductive network structure can be formed, thereby effectively reducing the stress concentration of the positive electrode film layer and improving the liquid retention rate of the positive electrode film layer during long cycles, further reducing the risk of electrode film shedding and the degree of polarization, improving the battery's kinetic performance and improving the battery's cycle life.

[0213] In some embodiments, the positive electrode film layer further includes a dispersant, and the dispersant includes hydrogenated nitrile rubber HNBR.

[0214] The polar groups (such as cyano, -CN) in the hydrogenated nitrile rubber HNBR molecules can interact with the hydroxyl groups (-OH) or metal oxide sites on the surface of the lithium-containing transition metal phosphate particles (such as hydrogen bonds, dipole effects), thereby enhancing the compatibility of the particles with the solvent, reducing the interfacial tension between the particles and the solvent, especially the interfacial tension of large particles, making the particles easier to disperse evenly, reducing aggregation caused by hydrophobicity, improving the dispersibility of large particles in the positive electrode film layer, and reducing the stress concentration generated during the die-cutting process of the positive electrode film layer.

[0215] At the same time, when the slurry dries to form a film, the elastic network structure of HNBR can buffer the shrinkage stress caused by solvent volatilization, reduce the re-aggregation of the conductive agent due to capillary force in this process, reduce the area ratio of the conductive agent agglomeration area, and improve the cycle life of the battery.

[0216] In some embodiments, the mass content of the dispersant is 0.5%-2% based on the mass of the positive electrode film layer.

[0217] In some embodiments, based on the mass of the positive electrode film layer, the mass content of the dispersant can be selected as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2% or any numerical range therebetween.

[0218] The mass content of the dispersant in the above range can achieve uniform dispersion of the particles in the positive electrode film layer while maintaining a high loading amount of the positive electrode film layer, and the battery has good capacity and cycle performance.

[0219] In some embodiments, the compaction density of the positive electrode tab of the battery cell in a full discharge state is 2.3 g / cm 3 -2.6 g / cm 3 .

[0220] In this application, the full discharge state refers to placing the battery in a 25°C oven environment, standing for 2h, waiting for the battery temperature to remain at 25°C, discharging the battery at 1 / 3C constant current to 2.5V, and then discharging at 0.1C constant current to 2.0V.

[0221] The compaction density of the positive electrode tab can be tested by methods known in the art. As an example, the battery is placed in a 25°C oven environment, standing for 2h, waiting for the battery temperature to remain at 25°C, discharging the battery at 1 / 3C constant current to 2.5V, and then discharging at 0.1C constant current to 2.0V, disassembling the battery, obtaining the positive electrode tab, treating the residual electrolyte with dimethyl carbonate solvent, drying the tab, cutting into small round pieces with an area of S, obtaining its mass W1, and using a micrometer to measure the thickness T1 of the positive electrode tab, then wiping off the positive electrode film layer of the tab after weighing, weighing the mass of the current collector, denoted as W2, and using a micrometer to measure the thickness T2 of the current collector, then the compaction density PD of the positive electrode tab = (W1-W2) / [(T1-T2)×S].

[0222] In some embodiments, the compaction density of the positive electrode tab of the battery in a full discharge state can be selected from 2.3 g / cm 3 , 2.31 g / cm 3 , 2.32 g / cm 3 , 2.33 g / cm 3 , 2.34 g / cm 3 , 2.35 g / cm 3 , 2.36 g / cm 3 , 2.37 g / cm 3 , 2.38 g / cm 3 , 2.39 g / cm 3 , 2.40 g / cm 3 , 2.41 g / cm 3 , 2.42 g / cm 3 , 2.43 g / cm 3 , 2.44 g / cm 3 , 2.45 g / cm 3 , 2.46 g / cm 3 , 2.47 g / cm 3 , 2.48 g / cm3 2.49 g / cm3 3 2.50 g / cm3 3 2.51 g / cm3 3 2.52 g / cm3 3 2.53 g / cm3 3 2.54 g / cm3 3 2.55 g / cm3 3 2.56 g / cm3 3 2.57 g / cm3 3 2.58 g / cm3 3 2.59 g / cm3 3 2.60 g / cm3 3 or any numerical range between any two of the above values.

[0223] In some embodiments, the positive electrode film layer has a porosity of 14-28%.

[0224] The porosity of the positive electrode film layer can be tested as follows. The cross-sectional SEM image of the positive electrode film layer obtained in the manner described above is imported into ImageJ software, a straight line tool is selected, a ruler length in the image is marked using the straight line, and “Analyze Set Scale” is clicked to set the ruler parameters in the software according to the ruler length in the image. A rectangular tool is selected, the part of the image outside the ruler area is selected, the selected area is copied using “Image Duplicate”, the image format is adjusted using “Image Type 8 bit”, “Analyze Set Measurements” is selected, the following five options are selected: “Area”, “Mean gray value”, “Area Fraction”, “Limit to threshold”, and “Feret’s diameter”, “Decimal places” is selected as 3, “Image”-“Adjust”-“Threshold” is selected in sequence, 0 and 100 are set in the “Threshold” box in sequence, and the pore data in the cross-sectional SEM image can be exported using the Analyze-Measure function. The pore image is obtained by using “Image”-“Overlay”-“Flatten”, “Apply” in “Threshold” is clicked, and “Analyze”-“Analyze Particles” is clicked, and the four columns on the left are checked, and the pore statistical data can be obtained.

[0225] It can be understood that in the embodiments of the present application, the "pores" in the positive electrode film layer section are identified by the color difference of the picture and the threshold value. The "pores" are not the pore data obtained in the exhaust test, and are mainly used to characterize the cross-sectional area between the particles in the positive electrode film layer. This method is better than the exhaust method because the porosity obtained by the exhaust method is related to the pores between the particles and the pores in the carbon material on the surface of the lithium iron phosphate particles, so it cannot objectively reflect the pores between the particles.

[0226] The porosity of the positive electrode film layer in the above range is beneficial to improve the liquid retention properties of the electrolyte, improve the ion diffusion properties of the positive electrode film layer with a certain area ratio of large particles, and improve the kinetic performance of the battery.

[0227] In some embodiments, the porosity of the positive electrode film layer can be selected as 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28% or any numerical range between any two of them.

[0228] In some embodiments, the positive electrode film layer is provided with a bottom coating layer at the bottom region close to the positive electrode current collector, the bottom coating layer comprises a conductive agent and a binder, the conductive agent comprises carbon nanotubes and conductive carbon black, and the binder comprises a vinylidene fluoride polymer.

[0229] In some embodiments, the thickness of the bottom coating layer is 0.5-5 μm.

[0230] In some embodiments, the thickness of the bottom coating layer can be selected as 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or any numerical range between any two of them.

[0231] The bottom coating layer provided by the embodiments of the present application helps to improve the adhesion between the positive electrode film layer and the positive electrode current collector and alleviate the stress concentration phenomenon at the large particles, thereby reducing the probability of positive electrode film layer falling off and improving the cycle stability of the battery. At the same time, compared with the direct contact between the positive electrode current collector and the positive electrode film layer, the contact area between the bottom coating layer and the positive electrode film layer is increased, which helps to increase the area of electron transmission between the current collector and the positive electrode film layer, thereby reducing the internal resistance of the electrode sheet and improving the kinetic performance of the battery.

[0232] In some embodiments, the thickness of the base film in the separator is 7-9 μm.

[0233] In some embodiments, the thickness of the base film in the separator can be selected as 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm or any numerical range between any two of them.

[0234] In some embodiments, the single-sided thickness of the ceramic layer in the separator is 2-4 μm.

[0235] In some embodiments, the thickness of a single side of the ceramic layer in the separator may be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, or any range therebetween.

[0236] In some embodiments, the thickness of a single side of the adhesive layer in the separator is 1 μm to 5 μm.

[0237] In some embodiments, the thickness of the adhesive layer on one side of the separator may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, or any range therebetween.

[0238] If the thickness of the adhesive layer is too low, the space for buffer expansion in the diaphragm is small and the adhesion between the diaphragm and the electrode is low. On the one hand, the stress of the film layer increases after expansion, and the probability of film layer shedding increases, affecting the cycle life of the battery. On the other hand, the probability of positive-negative short circuit increases, thereby affecting the safety performance of the battery. If the thickness of the adhesive layer is too large, it occupies a large space in the battery, thereby affecting the volume energy density of the battery. In the embodiment of the present application, the thickness of the adhesive layer is within the above range, which helps to balance the cycle life, safety performance and volume energy density of the battery.

[0239] In some embodiments, as Figure 5 As shown, the battery cell 5 includes a shell 50, and the laminated battery cell is accommodated in the shell 50. The size of the shell 50 in the length direction X is L1, the size of the shell 50 in the width direction Y is W1, and the size of the shell 50 in the thickness direction Z is H1, wherein 480mm≤L1≤720mm, 100mm≤W1≤150mm; 14mm≤H1≤22mm.

[0240] In some embodiments, L1 can be selected as 480mm, 490mm, 500mm, 510mm, 520mm, 530mm, 540mm, 550mm, 560mm, 570mm, 580mm, 590mm, 600mm, 610mm, 620mm, 630mm, 640mm, 650mm, 660mm, 670mm, 680mm, 690mm, 700mm, 710mm, 720mm, 750mm, 800mm, 850mm, 900mm, 950mm, 1000mm, 1050mm, 1100mm, 1150mm, 1200mm, 1250mm, 1300mm or any range therebetween.

[0241] In some embodiments, W1 may be 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, or any range of values ​​therebetween.

[0242] In some embodiments, H1 can be selected from 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, or any numerical range between any two of them.

[0243] The shell size of the battery cell in the embodiments of the present application is within the above range, which is beneficial to the battery to achieve better capacity.

[0244] In some embodiments, the size of the shell in the length direction is L1, and 450 mm≤L1≤650 mm.

[0245] When the size L1 of the shell in the length direction satisfies 450 mm≤L1≤650 mm, the length of the battery cell is shorter, which helps to shorten the diffusion path of the current, reduce the internal resistance of the pole piece, thereby reducing the heat production of the battery and improving the kinetic performance thereof. In addition, the shorter shell length helps to shorten the diffusion path of the electrolyte in the infiltration process, improve the infiltration rate and uniformity of the electrolyte, further promote the uniformity of lithium ion deintercalation in the cycle process, relieve stress concentration phenomenon, reduce the rebound degree of the film layer, and improve the cycle stability of the battery cell.

[0246] In some embodiments, the size of the shell in the length direction is L1, and 900 mm≤L1≤1300 mm.

[0247] When the size L1 of the shell in the length direction satisfies 900 mm≤L1≤1300 mm, the size of the battery cell is longer, which helps to reduce the volume ratio of the shell in the battery cell, and improve the load ratio of the active material. At the same time, the longer battery cell can reduce the number of batteries required in the battery module, simplify the structural design of the battery module, and reduce the number and complexity of structural components in the module, thereby improving the space utilization of the battery pack, and further helping to improve the volume energy density of the battery cell.

[0248] In some embodiments, as shown in FIG. 1, the material of the shell 50 is a soft package material, and the soft package material includes an aluminum plastic composite film. Figure 5

[0249] In some embodiments, the material of the shell includes one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), polyethylene (PE), and a composite film formed by aluminum.

[0250] The soft package material has a high ductility, so that the shell thereof is more lightweight, soft, and helps to improve the space utilization of the battery cell, thereby improving the energy density of the battery cell. In addition, the high barrier property of aluminum can effectively reduce the penetration of water and oxygen into the battery interior, reduce the decomposition of the electrolyte and the oxidation degree of the electrode material, thereby improving the service life of the battery. ​

[0251] In some embodiments, with continued reference to Figure 5 The shell 50 includes a first sealing area 51, which is arranged at at least one end of the jelly-roll along the width direction (Y direction). The first sealing area 51 includes a folded edge structure extending along the length direction (X direction), and the folded edge structure is provided with encapsulation glue, which is continuously arranged and fixed to the folded edge structure along the length direction (X direction).

[0252] The folded edge structure refers to a reinforcing structure formed by folding the encapsulation area, and the number of folds is not limited. For example, it can be a single folded edge structure folded once, or a double folded edge structure folded on both sides.

[0253] During the jelly-roll cycle, the SEI film of the positive film layer will thicken, and thus, large rebound and gas production will occur during long cycle. The sealing area of the soft package battery cell is used to seal the electrode assembly, but the sealing area has limited strength and is easily broken by large rebound and high gas production in the film layer.

[0254] The first sealing area of the present application further improves the sealing strength of the first sealing area by including a folded edge structure extending along the length direction. The continuous arrangement and fixation of the encapsulation glue along the length direction of the folded edge structure can further improve the encapsulation strength, realize the continuous reinforcement of the length direction of the sealing area, and reduce the probability of the jelly-roll breaking the sealing area in the package during the cycle rebound.

[0255] In some embodiments, the shell 50 includes at least one second sealing area 52, which is arranged at at least one end of the jelly-roll along the length direction of the shell, and the second sealing area 52 is arranged at the tab side of the jelly-roll.

[0256] It can be understood that the positive tab and the negative tab can be arranged on the same side of the jelly-roll, as shown in Figure 5 The positive tab and the negative tab can also be arranged on the opposite side of the jelly-roll.

[0257] In some embodiments, the battery cell 5 further includes a lead-out piece 53 connected to the tab of the battery cell, for example, the lead-out piece 53 can be welded to the tab. The lead-out piece 53 is an electrically conductive piece, at least part of the lead-out piece 53 is located outside the shell 50, the lead-out piece 53 is used as the electrode lead-out end of the battery cell 5, and the lead-out piece 53 is used to facilitate the electrical connection between the battery cell 5 and other battery cells 5 or other components. For example, the lead-out piece 53 can be in the form of a sheet.

[0258] Correspondingly, the lead-out piece 53 also includes a positive lead-out piece and a negative lead-out piece, the positive lead-out piece is connected to the positive tab, and the negative lead-out piece is connected to the negative tab.

[0259] The second sealing area is arranged at the side of the tab, and the tab needs to be connected with the lead-out piece. The connection strength between the lead-out piece and the shell material is relatively weak, so that the gas is easy to rush out from the second sealing area, which is beneficial to realize the directional pressure relief of the battery, reduce the influence on the adjacent battery cells during thermal runaway, and improve the service life of the battery as a whole.

[0260] In some embodiments, the outer periphery of the laminated cell is provided with a plurality of width-directional surrounding rubber rings, which are arranged at intervals in the length direction.

[0261] The interval arrangement of the width-directional surrounding rubber rings in the length direction is beneficial to fix the position between the pole pieces in the cell, reduce the probability of displacement of the cell during battery shaking, and is especially suitable for batteries with large length, which can effectively reduce the mutual displacement of the pole pieces in the length direction and thus cause lithium precipitation, and is beneficial to maintain the stability of the space structure inside the battery, so as to not affect the normal work of the battery.

[0262] In some embodiments, the capacity of the battery monomer at 25℃ is 100Ah-300Ah, which can be selected as 110Ah-190Ah, and further selected as 125Ah-180Ah.

[0263] In the present application, the capacity of the battery monomer is the meaning known in the art, which can be tested by the method known in the art. As an example, at 25℃, charge at 0.5C of the nominal capacity of the battery monomer to 3.65V, then charge at 3.65V constant voltage to 0.05C, stand for 10min, then discharge at 1C discharge rate to 2.5V, stand for 10min, calculate the capacity C in the discharge process by the formula C=I*t, unit Ah.

[0264] In some embodiments, the capacity of the battery monomer at 25℃ can be selected as 100Ah, 125Ah, 130Ah, 135Ah, 140Ah, 145Ah, 150Ah, 155Ah, 160Ah, 165Ah, 170Ah, 175Ah, 180Ah, 185Ah, 190Ah, 300Ah or any numerical range between any two values.

[0265] The battery monomer of the present application embodiment has a suitable shell size to accommodate the laminated cell, controls the reasonable large particle ratio in the film layer of the positive pole piece in the laminated cell, and has a higher capacity.

[0266] In some embodiments, the positive current collector can employ a metal foil or a composite current collector. For example, as a metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0267] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0268] In some embodiments, the negative electrode film layer includes a negative active material. As an example, the negative active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, and hard carbon. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative active material can also be used. These negative active materials can be used alone or in combination with two or more.

[0269] In some embodiments, the negative electrode film layer can also optionally include a binder. The binder can be selected from at least one of the following: styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0270] In some embodiments, the negative electrode film layer can also optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0271] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative current collector, and then performing processes such as drying, cold pressing, and the like to obtain the negative electrode sheet.

[0272] A second aspect of the present application provides a battery device, comprising the battery cell provided by the first aspect of the present application.

[0273] The battery device disclosed in the embodiments of the present application can be used in various energy storage systems that use the battery device as a power source or use the battery device as an energy storage element. In addition to being used in vehicles, the battery device can also be used for, but not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0274] In addition, the present application also provides an electrical device using a battery device as a power source, the electrical device including at least one of the battery cells, battery modules, or battery packs provided herein. The battery cells, battery modules, or battery packs can be used as a power source for the electrical device or as an energy storage unit for the electrical device.

[0275] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0276] Figure 6 It is an electric device as an example. The electric device disclosed in the embodiment of the present application can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device is provided inside the vehicle, and the battery device can be provided at the bottom, head or tail of the vehicle. The battery device can be used to power the vehicle. For example, the battery device can be used as an operating power source for the vehicle. The vehicle may also include a controller and a motor, and the controller is used to control the battery device to power the motor, for example, for the working power requirements of the vehicle during starting, navigation and driving. In some embodiments of the present application, the battery device can be used not only as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0277] An embodiment of the present application also provides an energy storage device that uses a battery device as a power source. The energy storage device may be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0278] Example

[0279] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be only for the purpose of explanation of the present application, and are not to be understood as a limitation thereof. In the examples, unless otherwise specified, the techniques or conditions not mentioned are those described in the literature in the art or those according to the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained commercially.

[0280] Example 1

[0281] (1) Preparation of positive electrode active material

[0282] Lithium carbonate, iron phosphate, titanium dioxide, vanadium pentoxide, sucrose, glucose and polyethylene glycol were added to deionized water and mixed in a premixing tank, wherein the ratio of lithium carbonate and iron phosphate was such that the molar ratio of lithium to iron was 1.02:1.0, and the mass content of sucrose was 2%, the mass content of glucose was 4%, and the mass content of polyethylene glycol was 5% based on the total mass of the mixed raw materials, and a mixed raw material with a solid content of 38% was obtained after uniform mixing;

[0283] The particle size Dv 50 of the lithium carbonate was 6 μm; the morphology of the iron phosphate particles was spherical; the titanium dioxide and vanadium pentoxide were both nanoparticles; the purity of the sucrose was ≥98%; the mass content of moisture of the glucose was <0.5%; and the weight average molecular weight of the polyethylene glycol was 1500.

[0284] The mixed raw material was ground twice in a sand mill, with coarse grinding for 1 h followed by fine grinding, and the slurry temperature was controlled to be less than 40°C during the grinding process, to obtain a mixed slurry; the particle size Dv50 of the solid particles in the mixed slurry was 0.40 μm, and spray drying was performed to obtain a dried precursor powder, and the particle size Dv50 of the dried precursor powder was 55.50 μm.

[0285] The precursor powder was subjected to two-stage temperature rising sintering in a nitrogen atmosphere to obtain a positive electrode active material: the temperature was raised from 25°C to 460°C at a temperature raising rate of 2°C / min (first temperature raising stage), and the temperature was kept constant for 3 h; the temperature was raised from 460°C to 780°C at a temperature raising rate of 5°C / min (second temperature raising stage), and the temperature was kept constant for 12 h; wherein the gas flow rate in the temperature raising stage was greater than that in the constant temperature stage, and the ratio was 1.5:1, and the total gas flow rate was 1350 cm 3 / h, and the temperature was lowered after completion; and airflow pulverization was performed to obtain a lithium iron phosphate positive electrode active material with a carbon material on the surface, and the particle size Dv50 was 1.6 μm, wherein the mass content of Ti element was 1050 ppm and the mass content of V element was 950 ppm based on the total mass of the positive electrode active material.

[0286] The above Dv10, Dv50 and Dv90 refer to the data obtained by Malvern laser scattering method.

[0287] (2) Preparation of the positive electrode sheet

[0288] The positive electrode active material with a mass ratio of 93.9%, the conductive agent with a mass ratio of 2%, the binder polyvinylidene fluoride with a mass ratio of 3%, and the dispersant HNBR with a mass ratio of 1.1% were mixed in the solvent N-methyl pyrrolidone, and then fully mixed in a stirring tank, stirring, which included first stirring and second stirring. The first stirring was at a stirring speed of 600 rpm for 30 min, and the second stirring was at a stirring speed of 1600 rpm for 260 min. After dispersion, the positive electrode slurry was prepared. After the stirring process was completed, the positive electrode slurry was transported to the coating process. The mass ratios of the positive electrode active material, the conductive agent, the binder, and the dispersant were calculated based on the total mass of the solids in the positive electrode slurry. The conductive agent included conductive carbon black with a mass ratio of 1.33% and single-walled carbon nanotubes with a mass ratio of 0.67%. The conductive carbon black had a specific surface area of 85 m 2 / g and an oil absorption value of 200 ml / 100 g. The single-walled carbon nanotubes had an average length of 30 μm, a specific surface area of 300 m 2 / g, and a mass content of metal impurities in the single-walled carbon nanotubes < 1 wt%.

[0289] The positive electrode slurry was transferred and coated onto the current collector aluminum foil and dried, and the positive electrode sheet with a positive electrode film layer was obtained after hot pressing. The single-sided thickness of the positive electrode film layer was 105.64 μm, and the compaction density was 2.36 g / cm 3 . The transfer coating speed was 20 m / min.

[0290] The hot pressing process included three times of hot roller pressing processes. The hot roller pressing pressures were increased in turn, and the hot roller pressures were 40 tons, 60 tons, and 80 tons in turn. The hot roller temperature was 60℃. Before the first time of entering the hot roller compaction, the sheet was heated, and the heating temperature was 40℃.

[0291] Here, the compaction density refers to the compaction density under the full discharge state of the battery monomer, and the test method is described below.

[0292] The median value C 50 of the graphitization degree of the positive electrode film layer was 1.005. The porosity of the positive electrode film layer was 16.1%. The iron elution rate of the positive electrode material was 974 ppm. The total area ratio of the agglomeration area of the conductive agent was 1.99%.

[0293] The positive electrode sheet was divided into strips, punched into a specified shape, and sorted by weight through a weighing sorting machine, so as to be stacked by a stacking machine.

[0294] (3) Preparation of the positive electrode sheet

[0295] The natural graphite, the conductive agent conductive carbon black, the binder styrene-butadiene rubber (SBR) and the thickening agent sodium carboxymethyl cellulose (CMC) are mixed uniformly according to the weight percentage of 95:1:2:2 and deionized water is added, and after stirring and dispersing, a negative electrode slurry is obtained. The negative electrode slurry is coated on a copper foil substrate, and after drying, compaction, slitting and sheeting, a negative electrode sheet is obtained.

[0296] The negative electrode sheet is slitted and punched into a specified shape, and the punched negative electrode sheet is sorted by weight through a weighing sorting machine for sheeting by a sheeting machine.

[0297] (4) Separator

[0298] Polyvinylidene fluoride (PVDF) is dissolved in N-methyl pyrrolidone (NMP), stirred uniformly, then polyethylene glycol (PEG) is added as a pore-forming agent and stirred thoroughly to obtain a bonding layer solution. The bonding layer solution is applied to the above-mentioned base film with ceramic layers on both sides, and after pre-volatilization at 80°C and drying at 110°C, the PEG is dissolved out by immersing in deionized water to obtain a separator with a porous structure on both sides of the bonding layer. The thickness of the base film is 8 μm, the thickness of the single-sided ceramic layer is 3 μm, and the thickness of the single-sided bonding layer is 1 μm.

[0299] (5) Electrolyte

[0300] In an argon atmosphere glove box (H2O<0.1 ppm, O2<0.1 ppm), organic solvents dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), and ethylene carbonate (EC) are mixed uniformly.

[0301] Lithium hexafluorophosphate is then added and dissolved in the organic solvent to make the concentration of lithium hexafluorophosphate 1.05 mol / L, and vinylene carbonate (VC) is added and stirred uniformly to obtain the electrolyte of Example 1.

[0302] The mass content of dimethyl carbonate is 26%, the mass content of methyl ethyl carbonate is 43.3%, the mass content of ethylene carbonate is 17.3%, and the mass content of vinylene carbonate is 0.9%, based on the total mass of the electrolyte.

[0303] (6) Preparation of the battery

[0304] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence by using a stacking machine, and the separator can isolate the positive electrode and the negative electrode, to obtain a stacked battery cell. The stacked battery cell is subjected to a glue sticking process, so as to tightly wrap the battery cell. The stacked battery cell after the glue sticking is placed in an outer package, and the outer package is an aluminum plastic film made of an inner layer of polypropylene, an intermediate layer of aluminum foil, and an outer layer of nylon. The aluminum plastic film outer package is obtained by a pit forming machine and trimming to obtain a target shape and size. Then, the aluminum plastic film is subjected to heat sealing, so as to meet the sealing tension of the aluminum plastic film ≥ 25N / 8mm. The battery is subjected to vacuum baking, standing, injection of electrolyte, packaging, and then heat pressing and cold pressing of the soft package battery, the temperature of the heat pressing is 45℃, the time is 2 minutes, and the pressure is 90kg / cm 2 , the temperature of the cold pressing is 25℃, the time is 2 minutes, and the pressure is 90kg / cm 2 . Finally, the battery monomer is obtained through processes such as formation, vacuum exhaust, and edge cutting. The size of the battery monomer in the length direction is 600mm, in the width direction is 125mm, and in the thickness direction is 20mm.

[0305] The preparation method of Example 2-5 is basically the same as that of Example 1, except that the preparation method of the positive electrode active material and the positive electrode sheet is adjusted, which is as follows:

[0306] Example 2

[0307] (1) Preparation of positive electrode active material Lithium dihydrogen phosphate, ferrous oxalate, polyethylene glycol with a weight average molecular weight of 1000, polyethylene glycol with a weight average molecular weight of 1500, titanium dioxide, and vanadium pentoxide are uniformly mixed and ground in methanol to obtain a mixed raw material. The molar ratio of lithium to iron in the lithium dihydrogen phosphate and the ferrous oxalate is 1.02:1.0. The particle size D 10 of the ferrous oxalate is 6.2μm, the particle size D 50 is 60.8μm, and the particle size D 90 is 106.5μm. The mass content of Fe element in the ferrous oxalate is 30.6%, and the mass content of trivalent iron element is 0.03%.

[0308] The mixed raw material is subjected to multiple ball milling in a ball mill and is removed from the magnet to obtain a mixed slurry. The milling frequency and time are controlled, and the particle size Dv 50 of the mixed slurry after milling is 3.1μm.

[0309] The mixed slurry is spray dried to obtain a dry precursor powder material, and the appearance of the dry precursor powder material is light yellow and uniform in color.

[0310] The precursor powder is placed in a sintering furnace, and is heated at 2°C / min from 25°C to 360°C under a nitrogen atmosphere and is kept at this temperature for 3.5h, then heated at 5°C / min to a second temperature of 775°C, and is kept at this temperature for 10h, and after the end of the process, it is cooled. The mass content of Ti element is 1050ppm and the mass content of V element is 950ppm based on the total mass of the positive electrode active material.

[0311] The obtained material is broken by airflow crushing method with a classification frequency of 22Hz and a wind volume of 0.55MPa, to obtain a lithium iron phosphate positive electrode active material with a carbon material on the surface.

[0312] The above D10, D50, D90 and Dv50 refer to the data obtained by Malvern laser scattering method.

[0313] (2) Preparation of the positive electrode tab

[0314] The above positive electrode active material with a mass ratio of 93.9%, a conductive agent with a mass ratio of 2%, a binder polyvinylidene fluoride with a mass ratio of 3% and a solvent N-methyl pyrrolidone are mixed, then a dispersant HNBR with a mass ratio of 1.1% is added, and the mixture is fully mixed, stirred and dispersed in a stirring tank to form a positive electrode slurry; after the stirring process is completed, the positive electrode slurry is transported to a coating process; wherein the mass ratio of the positive electrode active material, the conductive agent, the binder and the dispersant is calculated based on the total mass of the solids in the positive electrode slurry; the conductive agent includes conductive carbon black with a mass ratio of 1.33% and single-walled carbon nanotubes with a mass ratio of 0.67%, the specific surface area of the conductive carbon black is 85m 2 / g, the oil absorption value is 200ml / 100g, the average length of the single-walled carbon nanotubes is 30μm, the specific surface area is 300m 2 / g, and the mass content of metal impurities in the single-walled carbon nanotubes is <1wt%;

[0315] The positive electrode slurry is transferred and coated onto an aluminum foil current collector and dried, and after hot pressing, a positive electrode tab with a single-sided thickness of 105.89μm and a compacted density of 2.36g / cm 3 The stirring includes pre-stirring and main stirring, the stirring speed of the pre-stirring is lower than that of the main stirring, the pre-stirring has a revolution speed of 25rpm and a rotation speed of 500rpm, and the pre-stirring time is 15min.

[0316] The hot pressing process includes three times of hot roller pressing process, the hot roller pressing pressure increases in sequence, and the hot roller pressing pressure is 35 tons, 55 tons and 75 tons in sequence; the hot roller temperature is 65°C; before the first time of entering the hot roller compaction, the tab is heated, and the heating temperature is 50°C. Here, the compacted density refers to the compacted density under the full discharge state of the battery monomer, and the test method is described below.

[0317] The positive electrode sheet is slitting, cutting into a predetermined shape, and the cut positive electrode sheet is graded by weight through a weighing sorting machine for the sheet stacking machine.

[0318] Example 3

[0319] (1) Preparation of positive active material

[0320] Lithium carbonate, iron phosphate, sucrose, glucose, titanium dioxide, vanadium pentoxide are added to water and mixed in a premix tank at a speed of 1800 rpm, wherein the ratio of lithium carbonate and iron phosphate is such that the molar ratio of iron and phosphorus is 0.975, the mass content of glucose is 3.8% compared to iron phosphate, and the mass content of sucrose is 1.9% compared to iron phosphate;

[0321] The mixed raw materials are ground twice in a sand mill, the first grinding is carried out under the condition of using zirconium oxide balls with a diameter of 0.6 mm at a speed of 500 rpm, the grinding time is 1 h, and the grinding cavity pressure is less than 0.3 MPa, and then the second grinding is carried out to obtain a mixed slurry, the particle size D V50 of the mixed slurry is 0.43 μm;

[0322] The mixed slurry is spray dried to obtain a precursor powder,

[0323] The precursor powder is sintered to obtain a lithium iron phosphate positive electrode material, and the sintering process includes:

[0324] First sintering: the precursor powder is sintered in a nitrogen atmosphere, heated from 25°C to 765°C at a heating rate of 5°C / min, and kept for 10 h, and the first sintering product is obtained after cooling;

[0325] Grinding and mixing: 0.5% of sucrose, 1% of glucose and 3.0% of polyethylene glycol based on the total mass of the first sintering product are added to the first sintering product, and the grinding (third grinding) is carried out in two groups, wherein the D V50 of the particles in the first group reaches 1.0 μm, the grinding is stopped (grinding condition: 550 rpm, grinding time 1 h), and the first group grinding product is obtained; the D V50 of the particles in the second group reaches 0.40 μm, the grinding is stopped (grinding condition: 500 rpm, grinding time 4 h), and the second group grinding product is obtained; the first group grinding product and the second group grinding product are mixed according to the mass ratio of 72:28 to obtain a mixed intermediate product; and the mixed intermediate product is spray dried;

[0326] Second sintering: the dried mixed intermediate product is sintered in a nitrogen atmosphere, heated from 25°C to 800°C at a heating rate of 5°C / min, and kept for 10 h, and the second sintered product is obtained after cooling.

[0327] After sintering is completed, cooling to below 100°C, the second sintered product is crushed by the method of air flow crushing, to obtain a lithium iron phosphate positive electrode active material with a carbon material on the surface, wherein the classification frequency of air flow crushing is 25 Hz, and the crushing gas pressure is 0.55 MPa. Among them, the mass content of Ti element is 1050 ppm, and the mass content of V element is 950 ppm, based on the total mass of the positive electrode active material.

[0328] (2) Preparation of positive electrode sheet

[0329] The above-mentioned positive electrode active material with a mass ratio of 93.9%, a conductive agent with a mass ratio of 2%, a binder polyvinylidene fluoride with a mass ratio of 3% are mixed in a solvent N-methyl pyrrolidone, then a dispersant HNBR with a mass ratio of 1.1% is added, and the positive electrode slurry is prepared after being fully mixed, stirred and dispersed in the stirring tank; after the stirring process is completed, the positive electrode slurry is transported to the coating process; wherein the mass ratio of the positive electrode active material, the conductive agent, the binder and the dispersant is calculated based on the total mass of the solids in the positive electrode slurry; the conductive agent includes conductive carbon black with a mass ratio of 1.33% and single-walled carbon nanotubes with a mass ratio of 0.67%, the specific surface area of the conductive carbon black is 85 m 2 / g, the oil absorption value is 200 ml / 100 g, the average length of the single-walled carbon nanotubes is 30 μm, the specific surface area is 300 m 2 / g, and the mass content of metal impurities in the single-walled carbon nanotubes is <1 wt%;

[0330] The positive electrode slurry is transferred and coated onto the current collector aluminum foil and dried, and the positive electrode sheet with a single-sided thickness of the positive electrode film layer of 106.21 μm and a compacted density of 2.37 g / cm 3 is obtained after hot pressing. Among them, the drying temperature is 95°C, and the speed is 2.0 m / min.

[0331] The hot pressing process includes three times of hot roller pressing process, and the hot roller pressing pressure increases in turn, and the hot roller pressing pressure is 35 tons, 55 tons and 75 tons in turn; the hot roller temperature is 65°C; before the first time entering the hot roller compaction, the sheet is heated, and the heating temperature is 50°C. Here, the compacted density refers to the compacted density under the full discharge state of the battery monomer, and the test method is described below.

[0332] The positive electrode sheet is slitted and punched into a specified shape, and the punched positive electrode sheet is sorted by weight through a weighing sorting machine for lamination by a laminating machine.

[0333] Example 4

[0334] The preparation method of Example 4 is basically the same as that of Example 1, except that the preparation process of the positive active material and the heat pressing process of the positive electrode plate are slightly different, and the specific differences include:

[0335] (1) The carbon source in the mixed raw materials is sucrose and glucose, the mass of sucrose is 2wt% compared to the mass of iron phosphate, and the mass of glucose is 4wt% compared to the mass of iron phosphate;

[0336] (2) The temperature rising sintering process is different. The precursor powder is sintered at least twice in a nitrogen atmosphere, the first sintering temperature is 765°C, and the holding time is 8 hours to obtain a primary sintered product.

[0337] 1.5wt% (based on the mass of the primary sintered product) of glucose, 3.0wt% (based on the mass of the primary sintered product) of polyethylene glycol, titanium dioxide and vanadium pentoxide are added to the primary sintered product, and after grinding uniformly, it is divided into two groups for secondary grinding. The grinding parameters of the two groups are different, and the D V 50 of the particles after the first group of grinding is 2.2μm, and the D V 50 of the particles after the second group of grinding is 0.4μm. The particles after the first group and the second group of grinding are mixed in a mass ratio of 30:70, and spray dried, and then subjected to secondary sintering. The second sintering temperature is 815°C, and the holding time is 10 hours.

[0338] Based on the total mass of the positive active material, the mass content of Ti element is 1050ppm, and the mass content of V element is 950ppm.

[0339] (3) The positive electrode slurry is transferred and coated onto the current collector aluminum foil and dried, and after heat pressing, a positive electrode plate with a single-sided thickness of 106.34μm and a compaction density of 2.37g / cm 3 is obtained. Among them, the drying temperature is 95°C, and the speed is 2.0m / min.

[0340] The heat pressing process includes three times of heat roller pressing process, and the heat roller pressing pressure increases in turn, and the heat roller pressing pressure is 35 tons, 55 tons and 70 tons in turn; the heat roller temperature is 65°C, and before the first time entering the heat roller compaction, the plate is heated, and the heating temperature is 50°C. Here, the compaction density refers to the compaction density under the full discharge state of the battery monomer, and the test method is described below.

[0341] Example 5

[0342] The preparation method of Example 5 is basically the same as that of Example 1, except that the sintering process of the positive active material and the heat pressing process of the positive electrode plate are different, specifically:

[0343] (1) The precursor powder is subjected to two-stage temperature rising sintering in a nitrogen atmosphere to obtain a positive electrode active material: temperature rising from 25°C to 440°C at a temperature rising rate of 2°C / min (first temperature rising stage), holding for 2.5 h; temperature rising from 440°C to 760°C at a temperature rising rate of 5°C / min (second temperature rising stage), holding for 11 h; and then increasing the airflow pulverization intensity to obtain a lithium iron phosphate positive electrode active material with a carbon material on the surface.

[0344] (2) The positive electrode slurry is transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single-sided thickness of 105.65 μm and a compacted density of 2.36 g / cm 3 of a positive electrode tab is obtained after hot pressing. The transfer coating speed is 20 m / min.

[0345] The hot pressing process includes three times of hot roller pressing process, and the hot roller pressing pressure increases in turn, and the hot roller pressing pressure is 45 tons, 60 tons and 80 tons in turn; the hot roller temperature is 60°C; before the first time of entering the hot roller compaction, the tab is heated, and the heating temperature is 40°C.

[0346] The preparation method of Examples 6-11 is basically the same as that of Example 1, except that the preparation method of the positive electrode tab is adjusted, which is as follows:

[0347] Example 6

[0348] The positive electrode slurry of Example 1 is transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single-sided thickness of 91.88 μm is obtained by adjusting the pressure size, calendering speed, roll gap, pressure holding time, calendering times, and coating surface density in the hot pressing process; the compacted density of the positive electrode tab is 2.36 g / cm 3 . The compacted density here refers to the compacted density under the full discharge state of the battery monomer, and the test method is described below. The number of laminates is kept unchanged, and the thickness of the battery monomer is adaptively adjusted according to the thickness of the positive electrode film layer.

[0349] Example 7

[0350] The positive electrode slurry of Example 1 is transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single-sided thickness of 116.09 μm is obtained by adjusting the pressure size, calendering speed, roll gap, pressure holding time, calendering times, and coating surface density in the hot pressing process; the compacted density of the positive electrode tab is 2.36 g / cm 3 . The compacted density here refers to the compacted density under the full discharge state of the battery monomer, and the test method is described below. The number of laminates is kept unchanged, and the thickness of the battery monomer is adaptively adjusted according to the thickness of the positive electrode film layer.

[0351] Example 8

[0352] The positive electrode slurry of Example 1 was transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single side thickness of 72.34 pm was obtained by adjusting the pressure, rolling speed, roll gap, holding time, rolling times, and coating surface density in the hot-pressing process. The compaction density of the positive electrode sheet was 2.36 g / cm3. 3 The compaction density here refers to the compaction density under the full discharge state of the battery monomer, and the test method is described below. The number of layers of the stack was kept unchanged, and the thickness of the battery monomer was adaptively adjusted according to the thickness of the positive electrode film layer.

[0353] Example 9

[0354] The positive electrode slurry of Example 1 was transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single side thickness of 72.34 pm was obtained by adjusting the pressure, rolling speed, roll gap, holding time, rolling times, and coating surface density in the hot-pressing process. The compaction density of the positive electrode sheet was 2.36 g / cm3. 3 The compaction density here refers to the compaction density under the full discharge state of the battery monomer, and the test method is described below. The number of layers of the stack was kept unchanged, and the thickness of the battery monomer was adaptively adjusted according to the thickness of the positive electrode film layer.

[0355] Example 10

[0356] The positive electrode slurry of Example 1 was transferred and coated onto an aluminum current collector foil and dried, and a positive electrode film layer with a single side thickness of 72.34 pm was obtained by adjusting the pressure, rolling speed, roll gap, holding time, rolling times, and coating surface density in the hot-pressing process. The compaction density of the positive electrode sheet was 2.36 g / cm3. 3 The compaction density here refers to the compaction density under the full discharge state of the battery monomer, and the test method is described below. The number of layers of the stack was kept unchanged, and the thickness of the battery monomer was adaptively adjusted according to the thickness of the positive electrode film layer.

[0357] Example 11

[0358] The positive electrode slurry was prepared by mixing the above-mentioned positive electrode active material with a mass fraction of 93.9%, the conductive agent with a mass fraction of 2%, and the binder polyvinylidene fluoride with a mass fraction of 3% in the solvent N-methyl pyrrolidone, then adding the dispersant HNBR with a mass fraction of 1.1%, and fully mixing and stirring in the stirring tank, wherein the first stirring speed was 400 rpm and the stirring time was 15 min, and the second stirring speed was 1200 rpm and the stirring time was 150 min. After the stirring process was completed, the positive electrode slurry was transported to the coating process.

[0359] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the preparation method of the positive electrode active material is adjusted, as follows:

[0360] Comparative Example 1

[0361] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the sintering process of the positive electrode active material is different. Specifically:

[0362] The precursor powder was sintered in a nitrogen atmosphere in two stages to obtain the positive electrode active material: the temperature was increased from 25°C to 500°C at a heating rate of 2°C / min (the first heating stage), and kept warm for 3.5 hours; the temperature was increased from 500°C to 800°C at a heating rate of 5°C / min (the second heating stage), and kept warm for 13 hours; and then the air flow crushing intensity was reduced to obtain a lithium iron phosphate positive electrode active material with carbon material on the surface.

[0363] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the preparation method of the diaphragm is adjusted, as follows:

[0364] Add polyvinylidene fluoride (PVDF) and a dispersant into deionized water and stir evenly; add a thickener and an aqueous binder to the stirred solution, and place it in a sander and stir evenly to obtain a bonding layer slurry; spray the bonding layer slurry onto a base film with a double-sided ceramic layer, and after pre-volatilization at 80°C and drying at 90°C, a diaphragm with an island structure bonding layer is obtained.

[0365] The thickness of the base film is 8 μm, the thickness of the single-sided ceramic layer is 3 μm, and the thickness of the single-sided adhesive layer is 1 μm.

[0366] Test method:

[0367] 1. Capacity of battery cells

[0368] At 25°C, charge the battery to 3.65V at a charge rate of 0.5C of the nominal capacity of the battery cell, then charge it to 0.05C at a constant voltage of 3.65V, let it stand for 10 minutes, and then discharge it to 2.5V at a discharge rate of 1C, let it stand for 10 minutes. The capacity C during the discharge process is calculated by the formula C=I*t, in Ah.

[0369] 2. Number of cycles until the capacity decays to 90%

[0370] At 25°C, charge the battery to 3.65V at a charge rate of 0.5C of the nominal capacity of the battery cell, then charge it to 0.05C at a constant voltage of 3.65V, let it stand for 10 minutes, and then discharge it to 2.5V at a discharge rate of 1C and let it stand for 10 minutes. The above charge and discharge is one cycle. The test is stopped until the battery capacity decays to 90% of the nominal capacity, which is recorded as the number of cycles @90%SOH.

[0371] Table 1

[0372]

[0373] Table 2

[0374]

[0375] As can be seen from Table 1 and Table 2 through the comparison of the examples and the comparative examples, in the section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of the particles with a particle size greater than or equal to 1 μm is 12%-50%, and the adhesive layer of the separator is a continuous layer with a porous structure, when the adhesive layer includes a vinylidene fluoride polymer, the battery monomer maintains good capacity while reducing the risk of mutual extrusion of the positive and negative electrode sheets in the thickness direction of the electrode sheet evolving into horizontal misalignment during the rebound process of the battery cell, reducing the probability of positive and negative electrode overlap and further triggering short circuit, and improving the cycle performance of the battery.

[0376] As can be seen from the comparison of Example 4 and Examples 1-3 and 5, in the section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of the particles with a particle size greater than or equal to 1 μm is 12%-40%, which is beneficial to further improve the phenomenon of stress concentration of large particles in the electrode sheet leading to electrode sheet rebound on the basis of maintaining high capacity of the battery, reduce the probability of contact between the negative electrode film layer and the positive electrode film layer of the electrode sheet, and further improve the cycle performance of the battery.

[0377] As can be seen from the comparison of Examples 8 and 9 and Examples 6 and 7, the single-sided thickness H of the positive electrode film layer is 90 μm-120 μm, which is beneficial to further improve the capacity of the battery.

[0378] As can be seen from the comparison of Example 7 and Examples 1-6 and 8-10, in the section of the positive electrode film layer along the thickness direction of the electrode sheet, in the cumulative distribution curve of the sphericity of the particles with a particle size greater than or equal to 1 μm, the median number L A50 of the sphericity is 0.67-0.75, which can further improve the stress concentration of large particles and reduce the rebound of the electrode sheet due to stress release during the cycle process, and further improve the cycle life of the battery monomer.

[0379] Table 3

[0380]

[0381] As can be seen from the comparison of Example 11 and Example 1, when the distribution uniformity of the particles with a particle size greater than or equal to 1 μm in the first region is 0.2%-3.5%, it is beneficial to reduce the risk of local excessive extrusion and local lithium ion transmission path blockage caused by uneven distribution of large particles, which increases the peripheral current density and is prone to lithium precipitation, so that the battery further improves the cycle performance of the battery on the basis of having good capacity.

[0382] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. In addition, other modes constructed by combining part of the configurations of the embodiments in a manner that a person skilled in the art can think of within the scope of the present application are also included in the scope of the present application.

Claims

1. A battery cell, characterized in that: The laminated battery core includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet; The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer includes lithium-containing transition metal phosphate particles, and at least a portion of the surface of the lithium-containing transition metal phosphate particles is provided with a carbon material; in a cross-section of the positive electrode film layer along the thickness direction of the plate, the area of ​​particles with a particle size of 1 μm to 5 μm accounts for 12% to 50%; The diaphragm includes a base film and a ceramic layer arranged on both sides of the base film, and a bonding layer arranged on at least one side of the ceramic layer close to the positive electrode plate and away from the base film. The bonding layer is a continuous layer with a porous structure and includes a vinylidene fluoride polymer.

2. The battery cell according to claim 1, wherein: In a cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​particles with a particle size of 1 μm-5 μm accounts for 12%-40%.

3. The battery cell according to claim 1, wherein: The vinylidene fluoride polymer includes one or more of a vinylidene fluoride homopolymer and a copolymer of vinylidene fluoride and hexafluoropropylene.

4. The battery cell according to claim 1, wherein: The thickness of a single side of the positive electrode film layer is 70 μm-120 μm.

5. The battery cell according to claim 4, characterized in that The thickness of a single side of the positive electrode film layer is 90 μm-120 μm.

6. The battery cell according to claim 5, characterized in that The thickness of a single side of the positive electrode film layer is 100 μm-120 μm.

7. The battery cell according to claim 1, characterized in that The positive electrode film layer includes a first region, which is located at the top of the positive electrode film layer away from the positive electrode current collector. The distribution uniformity of particles with a particle size of 1 μm-5 μm in the first region is 0.2%-5%.

8. The battery cell according to claim 7, characterized in that The distribution uniformity of particles with a particle size of 1 μm to 5 μm in the first region is 0.2% to 3.5%.

9. The battery cell according to claim 1, characterized in that In the cross section of the positive electrode film along the thickness direction of the electrode, the median of the sphericity L in the cumulative distribution curve of the sphericity area of ​​particles with a particle size of 1μm-5μm is A50 It is 0.6-0.

8.

10. The battery cell according to claim 9, characterized in that The median of sphericity L A50 It is 0.65-0.

75.

11. The battery cell according to claim 10, characterized in that The median of sphericity L A50 It is 0.67-0.

75.

12. The battery cell according to claim 1, wherein In the cumulative distribution curve of the graphitization degree C of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the median value of the graphitization degree C 50 Greater than or equal to 0.95 and less than or equal to 1.20; wherein the graphitization degree C value is I G / I D , I G Indicates that the Raman spectrum is at 1580±100cm -1 The G peak intensity at I D Indicates that the Raman spectrum is at 1350±100cm -1 The D peak intensity at .

13. The battery cell according to claim 1, characterized in that In the cumulative distribution curve of the coating value B obtained by the laser microconfocal Raman spectrometer in the surface scanning mode of the positive electrode film layer, the median of the coating value B 50 The coverage value B is 0.30-0.60, where IP / ID is the Raman spectrum at 948±100cm -1 The P peak intensity at 1350 ± 100 cm -1 The D peak intensity at .

14. The battery cell according to claim 1, characterized in that The iron dissolution rate of the positive electrode material is 658ppm-1921ppm.

15. The battery cell according to claim 14, characterized in that The iron dissolution rate of the positive electrode material is 658ppm-1485ppm.

16. The battery cell according to claim 1, characterized in that The lithium-containing transition metal phosphate particles in the positive electrode film layer include components represented by the following general formula: Li m Fe x P y O j Q q Formula I Wherein, Q includes 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, and Br, 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, and 0≤q≤0.

1.

17. The battery cell according to claim 1, characterized in that The lithium-containing transition metal phosphate particles include titanium element. Based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of the titanium element is 500ppm-8000ppm.

18. The battery cell according to claim 17, characterized in that The mass content of titanium element is 1000ppm-3000ppm.

19. The battery cell according to claim 1, characterized in that The lithium-containing transition metal phosphate particles include vanadium element. Based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of the vanadium element is 500ppm-5000ppm.

20. The battery cell according to claim 19, characterized in that The mass content of vanadium element is 500ppm-3000ppm.

21. The battery cell according to claim 1, characterized in that The positive electrode film layer further includes a conductive agent. Based on the total area of ​​the cross section of the positive electrode film layer along the thickness direction of the electrode sheet, the total area of ​​the agglomerated region of the conductive agent accounts for 0.2%-6%.

22. The battery cell according to claim 21, characterized in that The total area of ​​the agglomerated regions of the conductive agent accounts for 1.5%-5%.

23. The battery cell according to claim 21, characterized in that The conductive agent includes carbon nanotubes, and the carbon nanotubes include one or more of single-walled carbon nanotubes, few-walled carbon nanotubes, and multi-walled carbon nanotubes.

24. The battery cell according to claim 22, characterized in that The conductive agent further includes conductive carbon black.

25. The battery cell according to any one of claims 21 to 24, characterized in that: The agglomeration region of the conductive agent includes carbon nanotubes and conductive carbon black.

26. The battery cell according to claim 25, characterized in that Based on the mass of the positive electrode film layer, the mass content C1 of carbon nanotubes satisfies: 0 < C1 ≤ 2.5%, and the mass content C2 of conductive carbon black satisfies: 0 < C2 ≤ 2.5%.

27. The battery cell according to claim 1, characterized in that The positive electrode film layer further includes a dispersant, and the dispersant includes hydrogenated nitrile rubber.

28. The battery cell according to claim 27, characterized in that Based on the mass of the positive electrode film layer, the mass content of the dispersant is 0.5% - 2%.

29. The battery cell according to claim 1, characterized in that The battery cell is in a fully charged state, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 -2.6g / cm 3 .

30. The battery cell according to claim 1, characterized in that The porosity of the positive electrode film layer is 14% - 28%.

31. The battery cell according to claim 1, characterized in that A bottom coating is provided in the bottom region of the positive electrode film layer close to the positive electrode current collector, and the bottom coating satisfies at least one of the following conditions: (1) The bottom coating includes a conductive agent and a binder. The conductive agent includes carbon nanotubes and conductive carbon black, and the binder includes a polyvinylidene fluoride polymer; (2) The thickness of the bottom coating is 0.5 μm - 5 μm.

32. The battery cell according to claim 1, characterized in that The separator satisfies at least one of the following conditions: (1) The thickness of the base film is 7 μm - 9 μm; (2) The single-sided thickness of the ceramic layer is 2 μm - 4 μm; (3) The single-sided thickness of the bonding layer is 1 μm - 5 μm.

33. The battery cell according to claim 1, characterized in that The battery cell includes a housing, the stacked electrode assembly is accommodated in the housing, the dimension of the housing in the length direction is L0, the dimension of the housing in the width direction is W0, and the dimension of the housing in the thickness direction is H0. 450 mm ≤ L0 ≤ 1300 mm, 100 mm ≤ W0 ≤ 150 mm, 14 mm ≤ H0 ≤ 22 mm.

34. The battery cell according to claim 33, characterized in that The dimension L0 of the housing in the length direction satisfies: 450 mm ≤ L0 ≤ 650 mm.

35. The battery cell according to claim 33, characterized in that The dimension L0 of the housing in the length direction satisfies: 900 mm ≤ L0 ≤ 1300 mm.

36. The battery cell according to claim 33, characterized in that The housing satisfies at least one of the following conditions: (1) The material of the housing is a soft package material, and the soft package material includes an aluminum-plastic composite film; (2) The housing includes a first sealing area, and the first sealing area is provided at at least one end of the stacked electrode assembly extending in the width direction; the first sealing area includes a folded edge structure extending in the length direction, and a packaging adhesive is provided on the folded edge structure. The packaging adhesive is continuously provided in the length direction and fixes the folded edge structure; (3) The housing includes at least one second sealing area, and the second sealing area is provided at at least one end of the stacked electrode assembly extending in the length direction of the housing, and the second sealing area is provided on the tab side of the stacked electrode assembly.

37. The battery cell according to claim 36, characterized in that The soft package material includes a composite film formed by one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, nylon, polyethylene terephthalate, polyethylene and aluminum.

38. The battery cell according to claim 1, characterized in that A plurality of rubber rings surrounding in the width direction are provided on the outer periphery of the stacked electrode assembly, and the rubber rings surrounding in the width direction are arranged at intervals in the length direction.

39. The battery cell according to claim 1, wherein: At 25 °C, the capacity of the battery cell is 110 Ah - 190 Ah.

40. The battery cell according to claim 39, characterized in that At 25 °C, the capacity of the battery cell is 125 Ah - 180 Ah.

41. A battery device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 40.

42. An electrical device, characterized in that: The electrical device includes the battery device as described in claim 41, and the battery device is used to provide electrical energy.

43. An energy storage device, characterized in that: The energy storage device comprises a battery device as claimed in claim 41, wherein the battery device is used to store electrical energy.

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