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

Abstract

The present application provides a battery cell, a battery device, an electrical device, and an energy storage device. The battery cell includes a laminated battery core, the laminated battery core includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer includes lithium-containing transition metal phosphate particles with carbon material provided on at least a portion of the surface, and the median value of the graphitization degree C of the positive electrode film layer obtained in the surface scanning mode of a laser microscopic confocal Raman spectrometer is C. 50 is 0.95-1.20, and the graphitization degree C value is I G / I D , I G Indicates that the Raman spectrum is at 1580±100cm ‑1 G peak intensity, I D The Raman spectrum is at 1350±100cm ‑1 The D peak intensity at the battery cell is in the fully discharged state, and the compaction density of the positive electrode sheet is 2.3-2.6g / cm 3 The battery cell of the present application has both high capacity and good cycle performance.

Description

[0001] This application claims priority to PCT international application No. PCT / CN2025 / 094409, filed on May 12, 2025, entitled “Battery Cell, Battery Device, Electrical Device, and Energy Storage Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of lithium-ion secondary battery cells, and in particular to a battery cell, a battery device, an electrical device, and an energy storage device. Background Art

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

[0004] As the market pursues longer battery life and longer battery life, higher requirements are being placed on battery capacity and cycle performance. However, existing technologies struggle to achieve simultaneous improvements in both performance and cycle life, making achieving a balance between the two a pressing technical challenge in this field. Summary of the Invention

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

[0006] The first aspect of the present application provides a battery cell, the battery cell includes a laminated battery core, the laminated battery core includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer includes lithium-containing transition metal phosphate particles with carbon material provided on at least a portion of the surface, and the median value of the graphitization degree C of the positive electrode film layer obtained in the surface scanning mode of a laser microscopic confocal Raman spectrometer is C 50 is 0.95-1.20, wherein the graphitization degree C value is 1 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 the battery cell is in a fully discharged state, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 -2.6g / cm 3 .

[0007] This application adopts a laminated battery cell structure and increases the compaction density of the positive electrode sheet to reduce the ineffective space inside the battery cell, improve space utilization, and thus increase the volume energy density and capacity of the battery cell, while regulating the median graphitization degree C 50 (Reflecting the degree of order of the carbon coating material), reducing the friction resistance between particles, enhancing the sliding ability of particles in the positive electrode film layer, reducing the stress concentration in the positive electrode film layer, and reducing the risk of film shedding during the cycle, ultimately achieving an effective balance between high capacity and good cycle performance of the battery.

[0008] In any embodiment, in the cumulative distribution curve of the graphitization degree C value 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 It is 1.01-1.13.

[0009] The graphitization degree of the positive electrode film layer is within the above range, which helps to further improve the sliding ability of the particles in the positive electrode film layer, reduce stress concentration in the positive electrode film layer, and reduce the risk of film shedding during the cycle, thereby further improving the cycle life of the battery cell.

[0010] In any embodiment, based on the total area of ​​particles in the cross section of the positive electrode film along the thickness direction of the electrode sheet, the area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm accounts for 12%-50%, and can be optionally 12%-40%.

[0011] The area proportion of particles with a particle size R1 satisfying R1 ≥ 1000 nm in the cross-section of the positive electrode film layer along the thickness direction of the electrode is in the range of 12%-50%, and further in the range of 12%-40%. This can not only improve the compaction density of the electrode, but also not increase the probability of film shedding, thereby improving the energy density of the battery cell while alleviating the capacity diving problem and taking into account the cycle life of the battery.

[0012] In any embodiment, 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 particle size R1 satisfying R1 ≥ 1000 nm is R1A1 50 is 0.6-0.8, optionally 0.65-0.75, and further optionally 0.67-0.75.

[0013] In the cross section of the positive electrode film along the thickness direction of the positive electrode sheet, in the cumulative distribution curve of the spherical area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50 Within the range of 0.65-0.75, and further within the range of 0.67-0.75, it is beneficial to further reduce the stress concentration at large particles in the positive electrode film layer of the laminated battery cell, thereby reducing the probability of film shedding and improving the cycle life of the battery.

[0014] In any embodiment, in the cumulative distribution curve of the coverage value B obtained by the laser microconfocal Raman spectrometer surface scanning mode, the median B of the coverage value B is 50 is 0.30-0.60, where the coating value B is I P / I D , where I P Indicates that the Raman spectrum is at 948±100cm -1 The intensity of the P peak at I D Indicates that the Raman spectrum is at 1350±100cm -1 The D peak intensity at .

[0015] Median B of the coating value of the positive electrode film 50 Being within the above range indicates that the carbon coating material of the positive electrode active material is relatively dense and uniform, which is beneficial to improving the slip uniformity of the positive electrode film layer during rolling and reducing the stress concentration phenomenon in the positive electrode film layer; in addition, with the help of dense and uniform carbon coating material, large particles in the positive electrode film layer are easier to slip during the compaction process, thereby reducing the stress concentration phenomenon at the large particles in the positive electrode film layer, reducing the probability of film falling off, improving the battery capacity diving problem, and increasing the cycle life of the battery.

[0016] In any embodiment, the lithium-containing transition metal phosphate particles include components represented by the following general formula:

[0017] Li m Fe x P y O j Q q Formula I,

[0018] 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.

[0019] In any embodiment, 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.

[0020] In any embodiment, 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.

[0021] In any embodiment, the iron dissolution rate of the positive electrode material is 658 ppm-1921 ppm, and can be optionally 658 ppm-1485 ppm.

[0022] In any embodiment, based on the total mass of the lithium-containing transition metal phosphate particles, the mass content of titanium element is 500 ppm-8000 ppm, and optionally 1000 ppm-3000 ppm.

[0023] In the embodiment of the present application, a high content of titanium is added to the lithium-containing transition metal phosphate particles, so that the reactivity 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 stress concentration in the positive electrode film layer, reduce the probability of film shedding, and improve the battery energy density while taking into account the cycle life of the battery.

[0024] In any embodiment, based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of vanadium element is 500 ppm-5000 ppm, and can be optionally 500 ppm-3000 ppm.

[0025] 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.

[0026] In any embodiment, the porosity of the positive electrode film layer is 14%-28%.

[0027] The porosity of the positive electrode film is within the above range, and the film has good electrolyte wettability and tortuosity, which facilitates the diffusion of lithium ions in the liquid and solid phases, helps reduce concentration polarization in thick electrode sheets, and improves the battery's dynamic performance. It also helps alleviate the volume expansion of the positive electrode sheet during cycling, reduces mechanical stress in the film, and reduces stress concentration, thereby reducing the risk of film shedding.

[0028] In any embodiment, the resistivity of the positive electrode film layer is 10Ω·cm-35Ω·cm.

[0029] The resistivity of the positive electrode film layer is within the above range, which is beneficial to reducing the electron transmission impedance, reducing the charge and discharge polarization, and improving the battery's rate performance and cycle performance.

[0030] In any embodiment, the thickness of the positive electrode film layer on one side is denoted as H, and H is 70 μm-120 μm.

[0031] In any embodiment, the thickness of the positive electrode film layer on one side is denoted as H, and H is 90 μm-120 μm.

[0032] The thickness of the positive electrode film layer on one side being within the above range helps to increase the positive electrode active material loading in the battery, increase the capacity of the battery, and at the same time reduce the risk of film shedding during the cycle.

[0033] In any embodiment, the thickness of the positive electrode film layer on one side is denoted as H, and H is 100 μm-120 μm.

[0034] Increasing the thickness of the positive electrode film layer helps to increase the loading amount of the positive electrode active material and helps to increase the capacity of the battery. However, the applicant has found that when the thickness of the single side of the positive electrode film layer is greater than or equal to 100μm, the volume expansion of the positive electrode film layer is more significant during the battery cycle, thereby generating greater stress, and the stress concentration phenomenon in the positive electrode film layer is more significant. The risk of film shedding increases, thereby affecting the cycle performance of the battery. The embodiment of the present application increases the capacity of the battery by increasing the thickness of the positive electrode film layer, and at the same time controls the median C value of the graphitization degree of the positive electrode film layer in the cumulative distribution curve of the graphitization degree C value obtained in the surface scanning mode of the laser microscopic confocal Raman spectrometer. 50 , improving the slip ability between particles in the positive electrode film layer, thereby helping to reduce the stress concentration phenomenon in the film layer, reducing the risk of film layer shedding, and thus improving the cycle life of the battery.

[0035] In any embodiment, the positive electrode film layer is provided with a primer layer in the bottom region near the positive electrode current collector, the primer 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.

[0036] In any embodiment, the primer layer has a thickness of 0.5 μm to 5 μm.

[0037] The undercoat provided in the embodiments of the present application helps improve the adhesion between the positive electrode film and the positive electrode current collector and alleviates stress concentration at large particles, thereby reducing the probability of positive electrode film shedding and improving the battery's cycling stability. Furthermore, compared to direct contact between the positive electrode current collector and the positive electrode film, the undercoat increases the contact area between the positive electrode film and the positive electrode film, helping to increase the area for electron transfer between the current collector and the positive electrode film, thereby reducing the internal resistance of the electrode sheet and improving the battery's dynamic performance.

[0038] In any embodiment, the positive electrode film layer further includes a dispersant, and the dispersant includes hydrogenated nitrile rubber (HNBR).

[0039] When HNBR is adsorbed on the surface of the particles in the slurry, its long-chain molecules will form a physical barrier around the particles, preventing the particles from approaching and aggregating with each other, so that the particles remain in a relatively independent dispersed state in the system. At the same time, HNBR can reduce the surface tension between the dispersion medium and the dispersed particles, making the particles more easily wetted by the medium, thereby promoting the dispersion of the particles in the medium. At the same time, it can also reduce the interfacial energy between the particles and reduce the aggregation of particles driven by interfacial energy. Furthermore, 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 reaggregation of the conductive agent due to capillary force in this process, reduce the area ratio of the conductive agent agglomeration area, and improve the battery's dynamic performance and cycle life.

[0040] In any embodiment, based on the mass of the positive electrode film layer, the mass content of the dispersant is 0.5%-2%.

[0041] The mass content of the dispersant is within the above range, which can achieve uniform dispersion of particles in the positive electrode film layer while maintaining a high loading capacity of the positive electrode film layer, reduce stress concentration in the positive electrode film layer, effectively alleviate the problem of battery capacity diving, and improve the cycle performance of the battery.

[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 area of ​​the agglomerated region of the conductive agent accounts for 0.5%-2.5%, and can be optionally 1.5%-2.5%.

[0043] Based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode, the 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 particularly beneficial to reducing the problem of kinetic decline of the film layer due to the growth of the ion transmission path, reducing the local polarization and even lithium plating problems generated by the battery during the cycle process, and improving the cycle life of the battery.

[0044] 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.

[0045] Due to the one-dimensional structure of carbon nanotubes, a network structure can be formed in the positive electrode film layer. On the one hand, the high elastic modulus of carbon nanotubes enables their network structure to not only serve as a bridge for stress propagation but also have a binding effect on the positive electrode film layer, inhibiting the rebound of lithium-containing transition metal phosphate particles, effectively alleviating stress concentration, reducing the risk of film layer shedding, and thus improving the problem of battery capacity decline; on the other hand, the excellent electrical conductivity of carbon nanotubes makes their network structure an efficient electron transport channel. Even if there is local film layer shedding, the thick electrode can still maintain high electron transport efficiency in the in-plane direction and thickness direction, thereby delaying the occurrence of capacity decline problems and further improving the kinetic performance and cycle life of the battery.

[0046] In any implementation manner, the conductive agent further includes conductive carbon black.

[0047] Conductive carbon black has a relatively high specific surface area and thus has good liquid retention ability. The thick electrode has a large expansion force during the cycling process, making it easy for the electrolyte to be extruded. The distribution of conductive carbon black in the positive electrode film layer is beneficial to improving the liquid retention ability of the thick electrode, further alleviating the phenomenon of capacity decline during battery cycling, and improving the cycle life of the battery.

[0048] In any implementation manner, 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 < C1 ≤ 2.5%.

[0049] When the mass contents of carbon nanotubes and conductive carbon black are within the above ranges, the agglomeration phenomenon of carbon nanotubes can be effectively alleviated and a good conductive network structure can be formed, thereby effectively reducing the stress concentration in the positive electrode film layer, increasing the liquid retention rate of the positive electrode during long cycling, further reducing the risk of film layer shedding and polarization degree of the electrode, improving the kinetic performance of the battery, taking into account the problem of capacity decline, and improving the cycle life of the battery.

[0050] In any implementation manner, the battery cell includes a housing, at least one of the stacked electrode cores is accommodated in the housing, the size of the housing in the length direction is L0, the size of the housing in the width direction is W0, and the size of the housing in the thickness direction is H0, where 450 mm ≤ L0 ≤ 1300 mm, 100 mm ≤ W0 ≤ 150 mm; 14 mm ≤ H0 ≤ 22 mm.

[0051] In any implementation manner, the size L0 of the housing in the length direction satisfies: 450 mm ≤ L0 ≤ 650 mm.

[0052] When the length dimension L1 of the shell satisfies 450mm≤L0≤650mm, the length of the battery cell is shorter, which helps to shorten the diffusion path of the current and reduce the internal resistance of the electrode, thereby reducing the heat generation of the battery and improving its dynamic performance; in addition, the shorter shell length helps to shorten the diffusion path of the electrolyte during the infiltration process, improve the infiltration rate and uniformity of the electrolyte, further promote the uniformity of lithium ion intercalation and deintercalation during the cycle, alleviate stress concentration, reduce the risk of film shedding, and improve the cycle stability of the battery cell.

[0053] In any embodiment, a length L0 of the housing satisfies: 900 mm ≤ L0 ≤ 1300 mm.

[0054] When the length dimension L0 of the housing satisfies 900mm≤L0≤1300mm, the battery cell is longer, which helps reduce the volume ratio of the housing within the battery cell and increase the active material load ratio. At the same time, longer battery cells 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 helping to increase the volume energy density of the battery cell.

[0055] In any embodiment, the material of the shell is a soft package material, and the soft package material includes an aluminum-plastic composite film, optionally including one or more of aluminum, polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), nylon, polyethylene terephthalate (PET), and polyethylene (PE).

[0056] In any embodiment, the shell includes a first sealing area, which is arranged at at least one end of the laminated battery cell extending along the width direction; the first sealing area includes a folding structure extending along the length direction, and the folding structure is provided with packaging glue, and the packaging glue is continuously arranged along the length direction and fixes the folding structure.

[0057] In any embodiment, the shell includes at least one second sealing area, which is arranged at at least one end of the laminated battery core along the length direction of the shell, and the second sealing area is arranged on the tab side of the laminated battery core.

[0058] In any embodiment, a plurality of rubber rings surrounding along the width direction are provided on the outer periphery of the laminated battery core, and the rubber rings surrounding along the width direction are arranged at intervals along the length direction.

[0059] The rubber rings that surround the width of the battery cell and are arranged at intervals in the length direction are beneficial to fixing the position between the electrodes in the battery cell and reducing the probability of the battery cell displacement during battery shaking. It is especially suitable for batteries with a longer length. It can effectively reduce the mutual displacement between the electrodes in the length direction and thus cause lithium plating, which is beneficial to maintaining the stability of the spatial structure inside the battery, thereby not affecting the normal operation of the battery.

[0060] In any embodiment, at 25° C., the capacity of the battery cell is 105 Ah-190 Ah, optionally 150 Ah-190 Ah.

[0061] In a second aspect of the present application, a battery device is provided, comprising the battery cell described in the first aspect of the present application.

[0062] In a third aspect of the present application, an electrical device is provided. The electrical device includes the battery device described in the second aspect of the present application, and the battery device is used to provide electrical energy.

[0063] In a fourth aspect of the present application, an energy storage device is provided. The energy storage device includes the battery device described in the second aspect of the present application, and the battery device is used to store electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 is a schematic diagram of a diaphragm according to one embodiment of the present application;

[0065] Figure 2 is a schematic diagram of a diaphragm of the prior art;

[0066] Figure 3 Schematic diagram of the surface morphology of the bonding layer according to one embodiment of the present application;

[0067] Figure 4 This is a schematic diagram of a soft-pack laminated battery of the present application;

[0068] Figure 5 It is a schematic diagram of an electrical device according to one embodiment of the present application.

[0069] Description of reference numerals:

[0070] 5 battery cell; 50 housing; 20 diaphragm; 201 base film; 202 ceramic layer; 203 adhesive layer; X length direction; Y width direction; Z thickness direction. DETAILED DESCRIPTION

[0071] 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.

[0072] " 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.

[0073] 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.

[0074] 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.

[0075] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0076] In this application, the terms "plurality" and "multiple" refer to two or more.

[0077] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0078] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0079] In embodiments of the present application, a battery device may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple soft-pack battery cells connected in series, parallel, or parallel via a busbar assembly. For example, a battery cell assembly is typically formed by arranging multiple soft-pack battery cells; a battery cell assembly may be a battery module, which is formed by arranging and securing multiple soft-pack battery cells to form a single module. For example, a battery module may be formed by bundling multiple battery cells using cable ties.

[0080] The battery device may be a battery pack, which includes a housing and one or more battery cell assemblies housed within the housing. The battery cell assemblies may be battery modules, which may be housed within the housing by securing the battery modules within the housing. Alternatively, the battery cell assemblies may be housed within the housing by directly securing multiple soft-pack battery cells to the housing.

[0081] In an embodiment of the present application, the housing may include a first housing and a second housing. The first housing and the second housing are fastened together to form an enclosed space within the housing to accommodate the battery cell assembly. Enclosed here means covered or closed, and may be sealed or unsealed. The first housing may be a top cover or a bottom plate. For example, the housing may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame to form an enclosed space within the housing to accommodate the battery cell assembly.

[0082] In the embodiment of the present application, the box body can be used as part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0083] In the embodiment of the present application, the battery cell may be a secondary battery, which refers to a battery cell that can be recharged to activate the active material after discharge and continue to be used; the battery cell may be a lithium-ion battery. The battery cell may be flat.

[0084] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module, or a battery pack.

[0085] A battery cell is the smallest unit that makes up a battery and can independently realize the functions of charge and discharge.

[0086] When there are multiple battery cells, they are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may 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 may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeams or longitudinal beams.

[0087] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0088] In some embodiments, battery cells may be assembled into a battery module. A battery module may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module.

[0089] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0090] A battery cell includes an electrode assembly and an electrolyte.

[0091] The electrode assembly usually includes a positive electrode sheet and a negative electrode sheet. The negative electrode sheet is the electrode that absorbs or lithiates lithium ions during charging and releases or delithiates lithium during discharging. The positive electrode sheet is the electrode that releases or delithiates lithium ions during charging and absorbs or lithiates lithium during discharging.

[0092] While lithium-containing transition metal phosphate particles offer significant advantages in cycling stability as positive electrode active materials, their intrinsic specific capacity is significantly lower than that of ternary materials. Applicants have discovered that their capacity and energy density disadvantages can be offset by increasing the compaction density of lithium-containing transition metal phosphate particles and combining them with a laminated cell structure. However, this process optimization also presents new technical challenges: Compared to ternary materials, lithium-containing transition metal phosphate particles are more structurally stable and less susceptible to breakage under high pressure. Therefore, lithium-containing transition metal phosphate particles are often subjected to higher pressures during the electrode sheet compaction process to achieve higher compaction density. Under high compaction density conditions, insufficient material slippage can easily lead to localized stress concentration during the electrode sheet rolling process. Furthermore, laminated cells have higher energy density than wound cells due to the lack of corners. However, the lack of corner constraints in laminated cells reduces the internal compressive force on the positive electrode membrane compared to wound cells, making it more likely that the positive electrode membrane will release from the mold. Film shedding not only directly reduces the active materials involved in the electrochemical reaction but also leads to an "islanding" effect, whereby isolated areas form between particles or between particles and the conductive agent, preventing good electrical contact and, consequently, preventing them from participating in the charge and discharge process, causing a drop in battery capacity. Furthermore, shedding active materials can obstruct ion transport pathways, increase the battery's internal resistance, cause localized overheating, and even increase the risk of thermal runaway, severely impacting the battery's cycle life and safety.

[0093] Based on this, the first aspect of the present application provides a battery cell, including a laminated battery cell, the laminated battery cell including a positive electrode sheet and a negative electrode sheet, the positive electrode sheet including a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer including lithium-containing transition metal phosphate particles with carbon material provided on at least a portion of the surface, the positive electrode film layer in the graphitization degree C value cumulative distribution curve obtained in the surface scanning mode of the laser microscopic confocal Raman spectrometer, the median graphitization degree C 50 is 0.95-1.20, wherein the graphitization degree C value is 1 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 the battery cell is in the fully discharged state, and the compaction density of the positive electrode sheet is 2.3g / cm 3 -2.6g / cm 3 .

[0094] The battery cell provided in the present application has a high capacity while improving its capacity drop problem, taking into account the cycle life of the battery.

[0095] Without being bound by any theory, this may be because: the use of a laminated battery cell structure can reduce the existence of invalid space inside the battery cell, effectively eliminate the inevitable corner gaps and interlayer gaps in the winding process, and make the entire battery cell structure more compact, thereby improving space utilization, increasing the volume energy density of the battery cell, and increasing the battery capacity; in addition, the regularity of the laminated structure also creates favorable conditions for improving the high compaction density process of the electrode. Under the same volume, the laminated battery cell can accommodate more electrode sheets, and with the high compaction density electrode sheets, the energy density and capacity output of the battery are further improved. At the same time, the applicant controls the cumulative distribution curve of the graphitization degree C value obtained by the positive electrode film layer in the surface scanning mode of the laser microscopy confocal Raman spectrometer, and the median value of the graphitization degree C 50 , in order to achieve a balance between battery capacity and cycle performance. The median C of the graphitization degree of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer 50 It reflects the degree of graphitization of the carbon coating on the surface of lithium transition metal phosphate particles, that is, the degree of order of the carbon coating on the surface of lithium transition metal phosphate particles. A higher degree of graphitization of lithium transition metal phosphate particles means a more ordered arrangement of carbon atoms, forming a near-ideal graphite layered structure. This structure can effectively reduce friction between particles, facilitating relative sliding of particles along the interlayer when stressed, exhibiting better slippage, thereby helping to alleviate stress concentration in the film layer, reduce the risk of film shedding, and thereby improve the cycle life of the battery.

[0096] In this application, a laminated battery cell refers to a battery cell formed by stacking a positive electrode sheet, a separator and a negative electrode sheet together.

[0097] In the present application, the positive electrode film layer contains lithium-containing transition metal phosphate particles, but the positive electrode film layer does not only refer to the positive electrode active material layer. Other film layers that are connected to the positive electrode active material layer and are difficult to distinguish, such as the primer layer, the liquid retention layer, etc. are collectively referred to as the positive electrode film layer.

[0098] In this application, lithium-containing transition metal phosphate particles refer to phosphate materials containing lithium and transition metal elements, and can be detected by any method known in the art. For example, they can be detected by combining an X-ray diffractometer (XRD) with an energy dispersive spectrometer or an inductively coupled plasma mass spectrometer.

[0099] In the present application, the carbon coating material disposed on at least a portion of the surface of the lithium-containing transition metal phosphate particles can be detected by any method known in the art. As an example, the carbon coating material disposed on at least a portion of the surface of the lithium-containing transition metal phosphate particles can be observed by characterizing the lithium-containing transition metal phosphate particles using a transmission electron microscope combined with an energy dispersive spectrometer.

[0100] In this application, the fully discharged state refers to the state after placing the battery in a 25°C oven environment, standing for 2 hours, and maintaining the battery temperature at 25°C, discharging the battery at a constant current of 1 / 3C to 2.5V, and then discharging at a constant current of 0.1C to 2.0V.

[0101] The compaction density of the positive electrode sheet can be tested using methods known in the art. As an example, place the battery in a 25°C oven environment and let it stand for 2 hours. When the battery temperature remains at 25°C, discharge the battery at a constant current of 1 / 3C to 2.5V and then at a constant current of 0.1C to 2.0V. Disassemble the battery to obtain the positive electrode sheet, treat the residual electrolyte with dimethyl carbonate solvent, dry the sheet, cut it into small discs with an area of ​​S, and obtain its mass as W1. Use a caliper to measure the thickness T1 of the positive electrode sheet, then wipe off the positive electrode film layer of the weighed sheet, weigh the mass of the current collector, record it as W2, and use a caliper to measure the thickness T2 of the current collector. The compaction density of the positive electrode sheet PD = (W1-W2) / [(T1-T2)×S].

[0102] In some embodiments, when the battery cell is fully charged, the compaction density of the positive electrode sheet can be 2.3 g / cm 3 , 2.31g / cm 3 , 2.32g / cm 3 , 2.33g / cm 3 , 2.34g / cm 3 , 2.35g / cm 3 , 2.36g / cm 3 , 2.37g / cm 3 , 2.38g / cm 3 , 2.39g / cm 3 , 2.40g / cm 3 , 2.41g / cm 3 , 2.42g / cm 3 , 2.43g / cm 3 , 2.44g / cm 3 , 2.45g / cm 3 , 2.46g / cm 3 , 2.47g / cm 3 , 2.48g / cm 3 , 2.49g / cm 3 , 2.50g / cm 3 , 2.55g / cm 3 , 2.60g / cm 3 or any range of values ​​between them.

[0103] In this application, the cumulative distribution curve of graphitization degree C value refers to a curve obtained by arranging at least 100 obtained C values ​​in ascending order, with graphitization degree as the horizontal axis and cumulative number percentage as the vertical axis. 50 The C value corresponding to the cumulative number of the vertical axis in the cumulative distribution curve of graphitization degree C is 50%. The median C value of graphitization degree 50 Compared with the point value, it can reflect the overall graphitization degree of the particles in the positive electrode film layer, that is, the degree of slippage; compared with the mean value, it can reduce the influence of extreme values ​​during the test process and improve the confidence of the test results.

[0104] The graphitization degree C of the positive electrode film can be obtained using a laser confocal Raman spectrometer in surface scanning mode. Specifically, a laser confocal Raman spectrometer (a high-precision Renishaw laser confocal Raman spectrometer) is used, with an excitation wavelength of 532 nm. An appropriate amount of the positive electrode film is scanned on its surface or along a cross-section along the thickness of the electrode sheet. The scanning area is 45 μm × 45 μm, divided into 10 × 10 grids. The grid vertices are used as test points, with a step size of 5 μm and a total of 100 scan points. This yields the C values ​​at different locations and a cumulative distribution curve of the C values ​​for the scanned area. The positive electrode film in this application can be either freshly prepared or obtained from a battery. Residual electrolyte salt particles are unavoidable on the surface of a disassembled battery. To improve test accuracy, it is preferred to perform a surface scan on a cross-section along the thickness of the electrode sheet to characterize the graphitization degree of the positive electrode film.

[0105] The graphitization degree C value of the positive electrode film 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±100cm -1 , which characterizes carbon sp 2 Hybrid structure; D peak position is 1350±100cm -1 , which characterizes a disordered structure, where disorder means that there is no regular arrangement between the carbon atoms in the structure. In graphite crystals, the carbon atoms in the same layer are arranged in sp 2 Hybridization forms covalent bonds, and the interlayer is van der Waals force, which makes the carbon in the graphite structure easy to slide. Therefore, the C value can characterize the graphitization degree of the positive electrode film. It can be understood that the graphitization degree in the positive electrode film mainly comes from the carbon material that has been graphitized in the positive electrode film, that is, the carbon coating material of the positive electrode active material. Although it is rich in sp 2 The hybrid structure of carbon nanotube conductive agent also has a relatively high I G / I D However, due to its low content and small diameter, its addition to the positive electrode film layer shows an extreme value in the Raman surface scan test of the positive electrode film layer, and will not affect the graphitization degree C in the positive electrode film layer.50 Therefore, the graphitization degree of the positive electrode film can also be used to characterize the graphitization degree of the positive electrode active material.

[0106] Those skilled in the art can adjust the graphitization degree of the active material particles by any known process. For example, adjusting the carbon source, sintering temperature, sintering time, sintering pressure, and sintering atmosphere can adjust the graphitization degree of the active material particles.

[0107] The higher the degree of graphitization of the carbon on the surface of the positive electrode active material, the higher the proportion of graphite structure carbon in the positive electrode film layer, and the easier it is for the particles to slip with the help of the highly graphitized carbon structure in the coating layer, reducing stress concentration in the electrode, reducing demolding, and improving the cycle performance of the battery.

[0108] In some embodiments, in the cumulative distribution curve of the graphitization degree C value 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 is 50 The amount can be selected from 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20 or any range therebetween.

[0109] In some embodiments, in the cumulative distribution curve of the graphitization degree C value 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 is 50 It is 1.01-1.13.

[0110] The graphitization degree of the positive electrode film layer is further within the above range, which helps to further improve the slippage of particles in the positive electrode film layer, reduce stress concentration in the positive electrode film layer, and thus further improve the long-cycle stability of the battery cell.

[0111] In some embodiments, in the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 It is 0.01-0.05.

[0112] Refer to the above, and so on, C 90 is the C value corresponding to the cumulative number of the vertical axis in the graphitization degree C value cumulative distribution curve when it accounts for 90%, C 10The C value corresponding to the cumulative number of the vertical axis in the graphitization degree C value cumulative distribution curve accounts for 10%. The concentration of C value is expressed as (C 90 -C 10 ) / C 50 Indicates. (C 90 -C 10 ) / C 50 It can reflect the size of most C values, is not affected by extreme values, and can also reflect the width of the distribution of the degree of graphitization of particles in the positive electrode film. A small concentration of C values ​​in the positive electrode film indicates that the width of the distribution of the degree of graphitization of particles in the positive electrode film is narrow and well concentrated.

[0113] In some embodiments, in the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 The optional values ​​are 0.01, 0.02, 0.023, 0.025, 0.03, 0.035, 0.036, 0.039, 0.04, 0.045, 0.05 or any numerical range therebetween.

[0114] The concentration of the C value of the positive electrode film layer is 0.01-0.05, indicating that the graphitization degree of the particles in the positive electrode film layer is highly consistent, which means that the positive electrode active material has good coating uniformity and consistency, which can reduce the slip resistance caused by the inconsistent graphitization degree of the particles in the positive electrode active material and the local stress concentration caused thereby, reduce the risk of demolding, and thus improve the long-cycle stability of the battery cell.

[0115] In some embodiments, in the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 It is 0.02-0.04.

[0116] The median graphitization degree of the positive electrode film C 50 Being within the above range is conducive to further improving the slippage between particles, further reducing local stress concentration while maintaining high dynamic performance of the battery, reducing the risk of demolding, and achieving a balance between battery performance and energy density.

[0117] In some embodiments, based on the total area of ​​particles in a cross section of the positive electrode film along the thickness direction of the electrode sheet, the area of ​​particles having a particle size R1 satisfying R1 ≥ 1000 nm accounts for 12%-50%.

[0118] In this application, the term "particle" refers to a positive electrode film layer with a fully identifiable boundary within the field of view at a certain magnification, such as 10,000x. Defects and scratches may exist within the particle, but no complete boundary sufficient to separate the particles can be identified within the particle. The positive electrode film layer in this application can be either freshly prepared or obtained from a disassembled battery.

[0119] The specific method for identifying particles is as follows: the positive electrode film layer is cut along the thickness direction of the electrode by an argon ion beam (as an example, the following equipment model can be selected: Leica EMTIC3XCP, working voltage: 6kV, working time: 6h), and after the cross section is exposed, a scanning electron microscope is used (as an example, the following equipment model can be selected: Hitachi SU8230, working voltage: 3kV, beam current: high, probe model: U (LA100), working distance <5mm) to observe the cross section of the positive electrode film layer along the thickness direction of the electrode. The field emission scanning electron microscope is used to collect images in the secondary electron mode at the non-edge position of the cross section of the positive electrode film layer (after observing the edge of the electrode under the scanning electron microscope, adjust the field of view to the center of the sample), and the electron microscope image is taken at a magnification of 10k times. The particles in the electron microscope image are analyzed using ImageJ software (1.46r, win64 version). The specific instructions for using ImageJ software are as follows: load the SEM image to be analyzed; use the Cellpose plug-in to identify particles and perform manual correction based on this; and use ImageJ to read and analyze the data. The specific method for identifying particles using the Cellpose plug-in is as follows: set the segmentation diameter parameter (diameter in the Segmentation module) to 15 pixels, click "runcyto3" to perform particle identification, and manually mark any particles in the image that were not identified, were not fully identified, or were incorrectly identified. Particles that were not identified, were not fully identified, or were incorrectly identified by the software primarily include the following: 1. Particles that are too large or have scratches on the particle surface, resulting in incomplete or incomplete identification; 2. Scratches on the particle surface caused by the argon ion beam cutting process may cause the software to misinterpret these scratches as particle boundaries, leading to identification errors; 3. Particles that were not successfully identified due to being too small; 4. Particles located at the edge of the electron microscope field of view, with the particle interior penetrated by the edge, preventing the complete morphology from being displayed, and partial recognition instead of the entire particle, resulting in identification errors.Manual calibration is performed on the unidentified or misidentified particles. The specific process is as follows: large particles located around the edges of the scanning electron microscope that are not fully displayed are deleted; other unidentified or misidentified particles are determined to have internal cracks and scratches. If no cracks and scratches are present, the particle is determined to be a single particle and manually labeled based on the observed particle boundary; if a crack and scratch are present, it is determined whether the crack and scratch penetrate the particle. If not, the particle is determined to be a single particle and manually labeled; if a crack and scratch penetrate the particle, it is determined whether the crack and scratch are linear or irregular; if the crack and scratch are irregular, it is determined to be the boundary between particles and the particles are divided along this boundary; if the crack and scratch are linear, contrast comparison is performed; if the contrast and scratch are not obvious and there is no crack, it is determined to be a scratch and labeled as a single particle; if the contrast and scratch are strong and there is a crack, it is determined to be the boundary between particles and labeled as two particles. After manual labeling, information irrelevant to the particles during the automatic image processing is deleted, thus completing the identification and labeling of the particles in the image.

[0120] It is understood that the particles in the cross-section of the positive electrode film along the thickness direction of the electrode sheet, especially those larger than 50 nm, are primarily derived from the positive electrode active material. Therefore, the present embodiment can accurately and objectively reflect the distribution of lithium-containing transition metal phosphate particles in the positive electrode film layer by observing and counting the particle area in the cross-section of the positive electrode sheet along the thickness direction of the electrode sheet.

[0121] In the prior art, a laser particle size analyzer is usually used to count the particle size of the positive electrode active material through the Malvern laser diffraction method. However, the applicant's research shows that since lithium-containing transition metal phosphate particles are easy to agglomerate, the test results obtained by the Malvern laser diffraction method based on the laser scattering principle often measure the particle size of its particle agglomerates, which cannot truly reflect the particle size of the particles in the positive electrode active material, let alone the dispersion state of the positive electrode active material in the film layer, because the positive electrode active material in the film layer will be more dispersed during the process of slurrying and film rolling. The test results obtained by the Malvern laser diffraction method are affected by the particle size, specific surface area, and degree of agglomeration of the positive electrode active material. Compared with the actual dispersion in the electrode, 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. Therefore, the particle size obtained by the Malvern laser diffraction method test cannot be equivalent to or analogous to the particle size obtained by statistics in the embodiments of the present application.

[0122] The specific method for testing the area percentage of particles with a particle size R1 satisfying R1 ≥ 1000 nm in a cross-section of the positive electrode film along the thickness direction of the electrode is as follows: Identify the particles in the positive electrode film according to the method described above in this application, import the image after particle identification and labeling into ImageJ software for analysis, set the scale based on the scanning electron microscope image, and use the "Feret diameter", "Area", "Round", and "Solidity" analysis functions to statistically analyze the particle size, area, sphericity, and roughness of the particles in the cross-section of the positive electrode film along the thickness direction of the electrode. According to the software manual (ImageJUserGuideIJ 1.46r), the "Feret" parameter obtained by analysis represents the maximum spacing between all parallel lines in the two-dimensional projection of the particle, which characterizes the particle size of the particle; the obtained "Area" parameter represents the pixel area of ​​the particle. Since particles with a particle size 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, which will cause large errors in the statistical results, particles with a particle size of less than 50 nm are not counted in the particle size statistical process of this application, and the particle statistical data corresponding to AR, Round or Solidity displayed as "NaN" are deleted. Calculate the sum of the "Area" parameters of particles with a particle size R1 satisfying R1 ≥ 1000 nm and the sum of the "Area" parameters of all particles, which are respectively used as the area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm and the total area of ​​the particles counted. The sum of the areas of particles with a particle size R1 satisfying R1 ≥ 1000 nm is divided by the total area of ​​the particles counted as the area ratio of particles with a particle size R1 satisfying R1 ≥ 1000 nm in the cross-section of the positive electrode film layer along the thickness direction of the electrode sheet.

[0123] In some embodiments, based on the total area of ​​the particles in the cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of particles whose particle size R1 satisfies R1 ≥ 1000 nm can be selected as 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% or any numerical range therebetween.

[0124] In some embodiments, based on the total area of ​​particles in a cross section of the positive electrode film along the thickness direction of the electrode sheet, the area of ​​particles having a particle size R1 satisfying R1 ≥ 1000 nm accounts for 12%-40%.

[0125] Large particles with an R1 of R1 ≥ 1000nm help increase the compaction density of the positive electrode sheet, thereby increasing the volumetric energy density of the battery cell. However, researchers have found that these large particles are prone to stress concentration, increasing the risk of positive electrode film shedding. Therefore, in a cross-section of the positive electrode film along the thickness of the electrode sheet, the area proportion of particles with an R1 of R1 ≥ 1000nm is within the range of 12%-50%, and further within the range of 12%-40%. This can both increase the compaction density of the electrode sheet and reduce the probability of film shedding. This improves the energy density of thick-coated lithium transition metal phosphate batteries while mitigating the capacity drop problem and maintaining the battery's cycle life.

[0126] In some embodiments, in the cumulative distribution curve of sphericity of particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50 It is 0.6-0.8.

[0127] In this application, the sphericity test method for particles with a particle size R1 of R1 ≥ 1000 nm in a cross-section of the positive electrode film along the thickness of the positive electrode plate is as follows: Particles in the cross-section of the positive electrode film are identified using the method described above in this application. The morphology of the particles in the cross-section of the positive electrode film along the thickness of the plate is analyzed using the "Shape Description" analysis function in ImageJ. According to the software manual (ImageJ User Guide IJ 1.46r), the "Round" parameter obtained from this analysis represents the ratio of the pixel area of ​​the particle to the area of ​​a circle with the fitted major diameter as its diameter, and can be used to characterize the sphericity of the particle. The closer the particle is to a spherical shape, the closer the ratio of the pixel area to the area of ​​a circle with the fitted major diameter is to 1. Therefore, the "Round" parameter obtained from the analysis is used to characterize the sphericity of the particle. According to the above method, to meet the statistically significant sample count, at least 10 scanning electron microscope images with non-overlapping fields of view are collected for each plate. Arrange the sphericity of at least 1000 particles obtained in ascending order, and use the sphericity as the horizontal axis and the cumulative area percentage as the vertical axis to obtain the cumulative distribution curve of the sphericity of the particles in the positive electrode film layer. 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%.

[0128] In some embodiments, in a cross section of the positive electrode film along the thickness direction of the positive electrode sheet, in the cumulative distribution curve of the sphericity of particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50The optional values ​​may be 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 range therebetween.

[0129] Those skilled in the art can adjust the sphericity of the particles by any known process. For example, the sphericity of the particles can be adjusted by grinding, polishing, chemical etching, mechanical stirring, extrusion, coating, granulation, adding surfactants, and adjusting the parameters of each process.

[0130] In some embodiments, in a cross section of the positive electrode film along the thickness direction of the positive electrode sheet, in the cumulative distribution curve of the sphericity of particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50 It is 0.65-0.75.

[0131] In some embodiments, in a cross section of the positive electrode film along the thickness direction of the positive electrode sheet, in the cumulative distribution curve of the sphericity of particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50 It is 0.67-0.75.

[0132] In the cross section of the positive electrode film along the thickness direction of the positive electrode sheet, in the cumulative distribution curve of the spherical area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm, L R1A50 Within the range of 0.65-0.75, and further within the range of 0.67-0.75, it is beneficial to further reduce the stress concentration at large particles in the positive electrode film layer of the thick-coated laminated battery cell, thereby reducing the probability of film shedding and improving the cycle life of the battery.

[0133] In some embodiments, in the cumulative distribution curve of the coverage value B obtained by the laser microconfocal Raman spectrometer in the surface scanning mode of the positive electrode film layer, the median coverage value B 50 is 0.30-0.60, where the coating value B is I P / I D , where I P Indicates that the Raman spectrum is at 948±100cm -1 The P peak intensity at I D Indicates that the Raman spectrum is at 1350±100cm -1 The D peak intensity at .

[0134] The cumulative distribution curve of the coating value B value is a curve obtained by arranging at least 100 B values ​​obtained in ascending order, with the coating value as the horizontal axis and the cumulative number percentage as the vertical axis. In order to reduce the influence of the coating value extreme value caused by the non-particle area in the positive electrode film layer on the test results, the median B value of the coating value is used. 50 Evaluate the density of the carbon coating material on the positive electrode active material. 50 It is the B value corresponding to when the cumulative number of the vertical axis in the cumulative distribution curve of the coverage value B value accounts for 50%.

[0135] In this application, the coating value (B) of the positive electrode film layer can be obtained by scanning with a laser confocal Raman spectrometer. As an example, a laser confocal Raman spectrometer (a high-precision Renishaw laser confocal Raman spectrometer) is used, and an excitation wavelength of 532 nm is selected. An appropriate amount of the positive electrode film layer is scanned on its surface or along a cross-section along the thickness direction of the electrode sheet. The scanning area is 45 μm × 45 μm, divided into 10 × 10 grids, with the grid vertices as test points, a step size of 5 μm, and a total of 100 scanning points. The B values ​​at different locations and the cumulative distribution curve of the B values ​​in the scanned area are thus obtained. The positive electrode film layer in this application can be either 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. To improve the accuracy of the test, it is preferred to perform a cross-section scan of the positive electrode film layer along the thickness direction of the electrode sheet to characterize the coating value of the positive electrode film layer.

[0136] The coating value B value 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±100cm -1 , which characterizes phosphate PO4 3- structure; D peak position is 1350±100cm -1 , which characterizes a disordered structure, where disorder refers to the irregular arrangement of carbon atoms within the structure. During testing, an excitation wavelength of 532 nm was selected, resulting in a shallow test depth. Therefore, in the surface scanning mode of a laser microconfocal Raman spectrometer, the carbon structure peak exhibited a higher intensity than the phosphate structure peak.

[0137] Those skilled in the art can adjust the coating value of active material particles by any known process. As an example, adjusting the carbon source type, carbon source addition amount, sintering temperature, sintering time, sintering pressure, and sintering atmosphere can all adjust the coating value of active material particles. The coating value B value can reflect the density of the carbon coating material on the surface of lithium-containing transition metal phosphate particles. The denser the carbon coating, the relatively lower the phosphate structure strength detected in the Raman spectrum, and the smaller the coating value B value of the positive electrode film layer.

[0138] In some embodiments, the positive electrode film layer further includes a coating layer disposed on at least a portion of the surface of the lithium-containing transition metal phosphate particles, and the median of the coating value B in the cumulative distribution curve of the coating value B obtained by the laser microscopic confocal Raman spectrometer surface scanning mode is 50 The amount can be selected from 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 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 range therebetween.

[0139] Median B of the coating value of the positive electrode film 50 Being within the above range indicates that the carbon coating material of the positive electrode active material is relatively dense and uniform, which is beneficial to improving the slip uniformity of the positive electrode film layer during rolling and reducing the stress concentration phenomenon in the thick-coated positive electrode film layer; in addition, with the help of the dense and uniform carbon coating material, the large particles in the positive electrode film layer are easier to slip during the compaction process, thereby reducing the stress concentration phenomenon at the large particles in the thick-coated positive electrode film layer, reducing the probability of the positive electrode film layer falling off, improving the battery capacity diving problem, and increasing the cycle life of the battery.

[0140] In some embodiments, the thickness H of a single side of the positive electrode film layer is 70 μm-120 μm.

[0141] In some embodiments, the thickness H of a single side of the positive electrode film layer is 90 μm-120 μm.

[0142] The thickness of the positive electrode film layer can be detected by any method known in the art. As an example, the thickness of the positive electrode film layer in a cross section of the positive electrode sheet along the thickness direction can be measured using a scanning electron microscope.

[0143] In some embodiments, the thickness H of the positive electrode film layer on one side may be 70 μm, 71 μm, 71.53 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, 81 μm, 82 μm, 83 μm, 84 μm, 85 μm, 86 μm, 87 μm, 88 μm, 89 μm, 90 μm, 91 μm, 92 μm, 93 μm, 94 μm, 95 μm, 96 μm, 97 μm, 98 μm, 99 μm, 100 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm 100μm, 101μm, 102μm, 103μm, 104μm, 105μm, 105.64μm, 105.89μm, 106μm, 106.66μm, 106.79μm, 107μm, 108μm, 109μm, 110μm, 111μm, 112μm, 113μm, 114μm, 115μm, 116μm, 117μm, 118μm, 119μm, 119.12μm, 120μm or any range between two thereof.

[0144] During long battery cycles, excessively thick cathode film layers can lead to significant volume expansion, increasing internal stress and making the electrode more susceptible to film shedding in the later stages of cycling. Maintaining a single-sided cathode film thickness within the above range helps further increase the positive electrode active material loading in the battery, boosting battery capacity while also reducing the risk of film shedding and improving battery cycling performance.

[0145] In some embodiments, the thickness H of a single side of the positive electrode film layer is 100 μm-120 μm.

[0146] Increasing the thickness of the positive electrode film layer helps to increase the loading amount of the positive electrode active material and helps to increase the capacity of the battery. However, the applicant has found that when the thickness of the single side of the positive electrode film layer is greater than or equal to 100μm, the volume expansion of the positive electrode film layer is more significant during the battery cycle, thereby generating greater stress, and the stress concentration phenomenon in the positive electrode film layer is more significant. The risk of film shedding increases, thereby affecting the cycle performance of the battery. The embodiment of the present application increases the capacity of the battery by increasing the thickness of the positive electrode film layer, and at the same time controls the median C value of the graphitization degree of the positive electrode film layer in the cumulative distribution curve of the graphitization degree C value obtained in the surface scanning mode of the laser microscopic confocal Raman spectrometer. 50 , improving the slip ability between particles in the positive electrode film layer, thereby helping to reduce the stress concentration phenomenon in the film layer, reducing the risk of film layer shedding, and thus improving the cycle life of the battery.

[0147] In some embodiments, the lithium-containing transition metal phosphate particles in the positive electrode film layer include components represented by the following general formula:

[0148] Li m Fe xP y O j Q q Formula I,

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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 doped modified materials and coated modified materials.

[0153] In some embodiments, the iron dissolution rate of the positive electrode material is 658 ppm-1921 ppm.

[0154] The iron dissolution 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 from the positive electrode film sample is weighed and added to 100.3 g of ascorbic acid solution with a mass concentration of 0.3% (the solvent is ultrapure water). After stirring at 500 revolutions per minute for 305 minutes, the solution is quickly aspirated using a 5 mL syringe, and the solution is filtered into a test tube using a 0.45 μm pore size filter. 1 mL of the supernatant is aspirated with a pipette, added to a glass volumetric flask and diluted 50 times. The solution is tested using an inductively coupled plasma mass spectrometer (ICP-OES) to obtain the iron concentration in the solution. The iron dissolution rate of the positive electrode material is calculated using the formula: (ICP test iron concentration × solution volume / mass of the fixed volume solution) × 100.3 g / mass of the positive electrode material powder, the solution volume is 50 mL, and the mass of the fixed volume solution is 1 g.

[0155] In some embodiments, the iron dissolution rate of the positive electrode material can be 658ppm, 700ppm, 800ppm, 890pm, 900ppm, 1000ppm, 1058pm, 1076pm, 1100ppm, 1143pm, 1200ppm, 1236pm, 1300ppm, 1311pm, 1384pm, 1349pm, 1400ppm, 1485pm, 1500ppm, 1531pm, 1600ppm, 1700ppm, 1800ppm, 1921ppm or any numerical range therebetween.

[0156] In some embodiments, the iron dissolution rate of the positive electrode material is 658 ppm-1485 ppm.

[0157] The iron dissolved in the positive electrode material mainly comes from the lithium-containing transition metal phosphate particles in the positive electrode active material. The iron dissolution rate depends on the number of lattice defects in the lithium-containing transition metal phosphate on the one hand, and on the integrity and density of the carbon coating on the surface of the positive electrode active material on the other hand. The lower the iron dissolution rate, the fewer lattice defects in the lithium-containing transition metal phosphate, which is beneficial to reducing the corrosion of the lattice in a weak acid environment; and the more complete and dense the carbon coating material on the surface of the positive electrode active material is, the more it inhibits the dissolution of iron ions in a weak acid environment. Positive electrode materials with iron dissolution rates within the above range have relatively few lattice defects and complete and dense carbon coating materials, which are beneficial to improving the compressive resistance and slippage of particles in the positive electrode film layer under large rolling pressure, increasing the compaction density of the positive electrode film layer and reducing stress concentration in the positive electrode film layer, improving the energy density of the battery while also improving the problem of battery capacity drop.

[0158] 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.

[0159] 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.

[0160] In some embodiments, based on the total mass of the lithium transition metal phosphate particles in the positive electrode film layer, the mass content of the titanium element can be selected as 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, 1400ppm, 1500ppm, 1600ppm, 1700ppm, 1800ppm, 1900ppm, 2000ppm, 2100ppm, 2200ppm, 2300ppm, 2400ppm, 2500ppm, 2600ppm, 2700ppm, 2800ppm, 2900ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm or any numerical range therebetween.

[0161] 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.

[0162] 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 cause the film layer of the positive electrode film layer to fall off. 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, reduce the probability of film layer shedding of the positive electrode film layer, and take into account the cycle life of the battery while improving the energy density of the battery.

[0163] At the same time, doping titanium into the positive electrode active material can help induce lattice distortion, reduce Li-O bond energy, increase lithium ion transfer rate, and improve the battery's kinetic performance. Uneven lithium ion diffusion in thick coatings is 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 kinetics of thick-electrode batteries.

[0164] 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.

[0165] 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, vanadium element and content are tested using inductively coupled plasma optical emission spectrometry in accordance with Appendix C of GB / T 33822-2017.

[0166] In some embodiments, based on the total mass of the lithium transition metal phosphate particles in the positive electrode film layer, the mass content of the vanadium element can be selected to be 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, 1400ppm, 1500ppm, 1600ppm, 1700ppm, 1800ppm, 1900ppm, 2000ppm, 2100ppm, 2200ppm, 2300ppm, 2400ppm, 2500ppm, 2600ppm, 2700ppm, 2800ppm, 2900ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, or 5000ppm.

[0167] 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.

[0168] 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.

[0169] A vanadium content within the above range helps improve the kinetic performance of the positive electrode sheet and the kinetic performance of thick-coated lithium transition metal phosphate batteries. Furthermore, the synergistic effect of titanium, vanadium, and carbon nanotubes in the positive electrode film helps form a good three-dimensional network, further enhancing the electronic and ionic conductivity of the positive electrode film, thereby further improving the kinetic performance of thick-coated lithium transition metal phosphate batteries.

[0170] In some embodiments, the porosity of the positive electrode film layer is 14%-28%.

[0171] In this application, the porosity of the positive electrode film layer can be tested in the following way. Import the cross-sectional scanning electron microscope image of the positive electrode film layer along the thickness direction of the electrode obtained in the manner described above into the ImageJ software, select the straight line tool, use the straight line to mark the ruler length in the image, click "Analyze Set Scale", and set the ruler parameters in the software according to the ruler length in the image. Select the rectangle tool, select the part of the image outside the ruler area, use "Image Duplicate" to copy the selected area, and use "Image Type 8 bit" to adjust the image format; select "Analyze Set Measurements", select the following 5 options: "Area", "Mean gray value", "Area Fraction", "Limit to threshold", "Feret's diameter", select 3 for "Decimal places", select "Image"-"Adjust"-"Threshold" in turn, set 0 and 100 in the "Threshold" box position in turn, and then use the Analyze-Measure function to export the pore data in the cross-sectional scanning electron microscope image. Use "Image" - "Overlay" - "Flatten" to export and obtain the pore image; click "Apply" in "Threshold", then click "Analyze" - "Analyze Particles", check the four columns on the left, and you can get the pore statistics.

[0172] It is understood that the "pores" in the positive electrode film cross-section are identified using image color difference and threshold values ​​in the present embodiment. This "pore" is not the porosity data obtained in the outgassing test, but is primarily used to characterize the gaps between particles in the positive electrode film cross-section. This method is superior to the outgassing method because the porosity obtained by the outgassing method is related to the pores between particles and the pores in the carbon coating material on the particle surface, and cannot objectively reflect the pores between particles.

[0173] In some embodiments, the porosity of the positive electrode film layer may be selected as 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28% or any range therebetween.

[0174] The porosity of the positive electrode film is within the above range, and the positive electrode film has good electrolyte wettability and tortuosity, which facilitates the diffusion of lithium ions in the liquid and solid phases, helps reduce concentration polarization in thick electrode sheets, and improves the battery's dynamic performance. At the same time, it helps to alleviate the volume expansion of thick coated electrode sheets during cycling, reduces mechanical stress in the film layer, and reduces stress concentration, thereby reducing the risk of film shedding in thick coated electrode sheets.

[0175] Especially in thick-coated soft-pack batteries, the gap between the shell and the electrode is small, the volume occupancy of the membrane layer is large, the electrolyte holding volume is reduced, and the porosity of the positive electrode membrane layer is within the above range, which helps to improve the liquid retention rate of the battery cell and improve the battery dynamic performance.

[0176] In some embodiments, the resistivity of the positive electrode film layer is 10Ω·cm-35Ω·cm.

[0177] In some embodiments, the resistivity of the positive electrode film layer is 10Ω·cm, 12Ω·cm, 14Ω·cm, 16Ω·cm, 18Ω·cm, 20Ω·cm, 22Ω·cm, 22Ω·cm, 24Ω·cm, 26Ω·cm, 28Ω·cm, 30Ω·cm, 32Ω·cm, 35Ω·cm or any range therebetween.

[0178] The resistivity of the positive electrode film layer is within the above range, which is beneficial to reducing the electron transmission impedance, reducing the charge and discharge polarization, and improving the battery's rate performance and cycle performance.

[0179] In some embodiments, the positive electrode film layer further includes a dispersant, and the dispersant includes hydrogenated nitrile rubber (HNBR).

[0180] HNBR is obtained by hydrogenating the double bonds of nitrile rubber. Its highly saturated main chain structure imparts excellent oil resistance, heat resistance, and aging resistance. This allows it to remain stable in various environments and systems when used as a dispersant, making it less susceptible to degradation or deterioration, thereby effectively dispersing the material. The HNBR molecular chain contains both polar nitrile groups and non-polar hydrocarbon segments. The polar nitrile groups can interact with certain polar substances or particle surfaces, adsorbing onto the surfaces of dispersed particles through hydrogen bonding and electrostatic interactions. The non-polar hydrocarbon segments, on the other hand, possess excellent lipophilicity and can stretch and disperse well in non-polar or weakly polar media, resulting in uniform dispersion of the particles.

[0181] When HNBR is adsorbed on the surface of the particles in the slurry, its long-chain molecules will form a physical barrier around the particles, preventing the particles from approaching and aggregating with each other, so that the particles remain in a relatively independent dispersed state in the system. At the same time, HNBR can reduce the surface tension between the dispersion medium and the dispersed particles, making the particles more easily wetted by the medium, thereby promoting the dispersion of the particles in the medium. At the same time, it can also reduce the interfacial energy between the particles and reduce the aggregation of particles driven by interfacial energy. Furthermore, 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 reaggregation of the conductive agent due to capillary force in this process, reduce the area ratio of the conductive agent agglomeration area, and improve the battery's dynamic performance and cycle life.

[0182] In some embodiments, the mass content of the dispersant is 0.5%-2% based on the mass of the positive electrode film layer.

[0183] 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%, 1.5%, 2% or any numerical range therebetween.

[0184] The mass content of the dispersant is within the above range, which can achieve uniform dispersion of particles in the positive electrode film layer while maintaining a high loading capacity of the positive electrode film layer, reduce stress concentration in the thickly coated lithium transition metal phosphate positive electrode film layer, and effectively alleviate the problem of battery capacity diving.

[0185] In some embodiments, the positive electrode film layer further includes a conductive agent, and based on the total area of ​​the cross section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​the agglomerated region of the conductive agent accounts for 0.5%-2.5%.

[0186] In the present application, 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 aggregated conductive agent can be seen under the high magnification of the scanning electron microscope, and the conductive agent agglomeration region often appears black agglomerate compared to other areas in the positive electrode film layer. With the help of image analysis software, the conductive agent agglomeration area refers to the area in the scanning electron microscope image where the conductive agent is obviously aggregated and appears black. Specifically, a scanning electron microscope image at a magnification of 3k was imported into ImageJ, and black conductive agent agglomeration regions with a Feret greater than or equal to 2μm were screened out. The sum of the areas of the screened regions was recorded as the area of ​​the conductive agent agglomeration region. The area ratio of the conductive agent agglomeration region was the ratio of the area of ​​the conductive agent agglomeration region to the total area of ​​the imported scanning electron microscope image. Three non-overlapping scanning electron microscope images were randomly selected, and the average of the area ratios of the conductive agent agglomeration regions was calculated as the "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."

[0187] In some embodiments, the positive electrode film layer also 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 area ratio of the agglomerated region of the conductive agent 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%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5% or any numerical range therebetween.

[0188] 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 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 particularly beneficial to reducing the problem of kinetic degradation caused by the increase of the ion transmission path in the thick coating film layer, reducing the local polarization and even lithium plating problems generated by the battery during the cycle process, and improving the cycle life of the battery.

[0189] At the same time, studies have shown that large-sized first 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 powder loss and shedding of the film layer, and improve the cycle life of the battery.

[0190] In some embodiments, the positive electrode film layer further includes a conductive agent, and based on the total area of ​​a cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​the agglomerated region of the conductive agent accounts for 1.5%-2.5%.

[0191] In the embodiments of the present application, the area ratio of the agglomerated region of the conductive agent is further within the above range, indicating that the conductive agent is more evenly distributed in the positive electrode film layer, and the content of the conductive agent is relatively low. While improving the kinetic performance of the positive electrode film layer, it helps to reduce the space occupied by the positive electrode active material due to excessive conductive agent, thereby further improving the volume energy density of the battery while improving the battery kinetic performance.

[0192] 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.

[0193] In this application, the term "carbon nanotube" refers to a carbon nanotube composed of carbon atoms in the form of sp 2 A nanomaterial consisting of several to dozens of coaxial hollow tubes formed by the curling of hybrid-bonded graphene sheets. Diameters typically range from a few to tens of nanometers, and lengths can range from microns to centimeters, exhibiting a high aspect ratio. Based on the number of graphene layers, carbon nanotubes can be classified as single-walled carbon nanotubes (SWCNTs), few-walled carbon nanotubes (FWCNTs), and multi-walled carbon nanotubes (MWCNTs). Carbon nanotubes possess excellent electrical conductivity and a high elastic modulus.

[0194] Because carbon nanotubes have a one-dimensional structure, they can form a network structure in the positive electrode film. On the one hand, the high elastic modulus of carbon nanotubes enables their network structure to not only serve as a bridge for stress propagation, but also has a binding effect on the thickly coated positive electrode film, inhibiting the rebound of lithium-containing transition metal phosphate particles, effectively alleviating stress concentration, reducing the risk of film shedding, and thus improving the problem of battery capacity plummeting. On the other hand, the excellent conductivity of carbon nanotubes makes their network structure an efficient electron transmission channel. Even if there is local film shedding, the thick electrode can still maintain high electron transmission efficiency in the in-plane direction and thickness direction, thereby delaying the occurrence of capacity plummeting and further improving the battery's dynamic performance and cycle life.

[0195] In some embodiments, the conductive agent further includes conductive carbon black.

[0196] The conductive carbon black has a relatively high specific surface area, and thus has good liquid retention ability. The thick electrode has a large swelling force during cycling, making it easy for the electrolyte to be extruded. The distribution of conductive carbon black in the positive electrode film layer is beneficial to improving the liquid retention ability of the thick electrode, further alleviating the phenomenon of capacity drop during battery cycling, and improving the cycle life of the battery.

[0197] In some embodiments, the agglomeration region of the conductive agent includes carbon nanotubes and conductive carbon black.

[0198] Researchers found that due to its high surface energy, carbon nanotubes are prone to agglomeration, resulting in uneven dispersion in the positive electrode film layer and unable to form an effective carbon nanotube network structure. The surface energy of conductive carbon black and carbon nanotubes is relatively close, and it can adsorb on the surface of carbon nanotubes to form a physical barrier, increasing the resistance to carbon nanotube agglomeration, reducing the direct contact between carbon nanotubes, and thus inhibiting the agglomeration phenomenon. Improve the distribution uniformity of carbon nanotubes in the positive electrode film layer. On the one hand, this helps to improve the conductivity of the thick-coated positive electrode film layer and the kinetic performance of the battery; on the other hand, it helps to exert the binding effect of carbon nanotubes on the positive electrode film layer, reduce the risk of shedding of the thick-coated positive electrode film layer, and further improve the kinetic performance and cycle life of the battery. In addition, the agglomeration of carbon nanotubes in the agglomeration region of the conductive agent will also cause blockage of the local ion transport path in the agglomeration region of the conductive agent. The combination of conductive carbon black can improve the lithium ion transport ability in this region, reduce local polarization, and further improve the cycle stability of the battery. In some embodiments, 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 < C1 ≤ 2.5%.

[0199] In some embodiments, based on the mass of the positive electrode film layer, the mass content C1 of 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 the numerical range between any two of them.

[0200] In some embodiments, based on the mass of the positive electrode film layer, the mass content C2 of 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 the numerical range between any two of them.

[0201] The mass content of carbon nanotubes and conductive carbon black is within the above range, which 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 plate during long cycles, further reducing the risk of plate film shedding and the degree of polarization, improving the battery's kinetic performance while taking into account the capacity diving problem and improving the battery's cycle life.

[0202] In some embodiments, the battery cell also includes a separator 20 arranged between the positive electrode plate and the negative electrode plate, the separator 20 includes a base film 201 and a ceramic layer 202 arranged on at least one side of the base film 201 and an adhesive layer 203 arranged on the side of the ceramic layer 202 away from the base film 201, the adhesive layer 203 is a continuous layer of a porous structure, and the adhesive layer 203 includes a vinylidene fluoride polymer.

[0203] In some embodiments, the battery cell further includes a separator disposed between the positive electrode sheet and the negative electrode sheet, the separator including a base film, a ceramic layer disposed on both sides of the base film, and an adhesive layer disposed on at least one side of the ceramic layer away from the base film.

[0204] The ceramic layers arranged on both sides of the base film are beneficial to improving the rigidity of the soft-pack battery and reducing local stress concentration.

[0205] In some embodiments, the battery cell further includes a separator disposed between the positive electrode sheet and the negative electrode sheet, the separator including a base film, ceramic layers disposed on both sides of the base film, and adhesive layers disposed on both sides of the ceramic layers away from the base film.

[0206] In some embodiments, the vinylidene fluoride polymer includes one or more of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0207] In some embodiments, the vinylidene fluoride-based polymer includes polyvinylidene fluoride (PVDF).

[0208] In the prior art, the adhesive layer of the diaphragm usually uses water-based PVDF, which presents an island structure in the diaphragm, such as Figure 2 As shown, this is beneficial for providing gaps for the expansion of the battery cell and is easy to manufacture; however, the contact area between the diaphragm adhesive layer and the electrode is small and the bonding force is weak.

[0209] The diaphragm provided in the embodiment of the present application uses a continuous layer of porous structure as a bonding layer, such as Figure 1 and Figure 3 As shown, compared with the adhesive layer in the prior art, the bonding area with the electrode is larger, so that the bonding between the diaphragm and the electrode is more firm and uniform; further, when the positive electrode film rebounds, it is beneficial to maintain the interface contact between the diaphragm and the positive electrode film, reducing the probability of film shedding.

[0210] It is understandable that the continuous adhesive layer may break and deform into a block structure due to contact or extrusion with the positive electrode sheet or the negative electrode sheet during the manufacturing or circulation process of the electrode sheet. The continuous structure referred to in this application means that at the microscopic level, such as when observed under a scanning electron microscope or an optical microscope, the adhesive layer of the diaphragm is continuous. In order to reflect the true morphology of the diaphragm, during the sampling process, it is preferred to sample the area where the adhesive layer of the diaphragm in the battery is not bonded to the positive electrode sheet or the negative electrode sheet. As an example, sampling is performed at the position of the diaphragm beyond the positive electrode sheet and the negative electrode sheet; or sampling is performed on the diaphragm near the surface of the electrode assembly. The diaphragm sampling area has less adhesion to the positive electrode sheet or the negative electrode sheet, and can better reflect the true state of the diaphragm.

[0211] Compared with wound cells, the extrusion between the diaphragm and the electrode in the laminated cell is smaller, and the diaphragm and the electrode are prone to relative displacement, thereby disturbing the film layer, and the film layer is prone to powder loss or falling off; in addition, it may also cause the positive and negative electrodes to overlap with each other, increasing the risk of internal short circuit in the battery cell. Therefore, the diaphragm provided in the embodiment of the present application is particularly suitable for laminated cells. The increase in the bonding force between the porous adhesive layer and the electrode helps to improve the bonding force between the diaphragm and the electrode and reduce the relative displacement between the diaphragm and the electrode, which helps to reduce the disturbance to the positive electrode film layer and reduce the probability of the film layer falling off, and helps to reduce the risk of the positive and negative electrodes overlapping and causing the battery cell short circuit.

[0212] In summary, when the vinylidene fluoride polymer in the bonding layer of the embodiment of the present application is selected from the above materials, it helps to form a continuous and uniform porous bonding layer. First, the bonding force between the bonding layer and the pole piece is improved and evenly distributed, which helps to reduce the stress concentration phenomenon in the thick coating of the lithium transition metal phosphate positive electrode film layer and reduce the risk of the film falling off, thereby helping to further improve the cycle life of the battery; secondly, the bonding layer is stably bonded to the positive electrode piece or the negative electrode piece, which helps to reduce the direct contact between the positive electrode piece and the negative electrode piece due to the relative displacement of the pole piece and the diaphragm, reduces the risk of internal short circuit, and helps to improve the safety performance of the battery; secondly, the porous bonding layer helps to maintain the porosity of the diaphragm, reserves space for the expansion of the battery cell, and further improves the cycle life of the battery.

[0213] 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).

[0214] In some embodiments, the ceramic layer includes one or more of aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), titanium oxide (TiO 2 ), silicon oxide (SiO 2 ), and boron nitride (BN).

[0215] Ceramic particles are flame-retardant and have a high hardness, making them resistant to deformation under heat and resulting in excellent dimensional stability. The low thermal conductivity of ceramic materials further prevents certain thermal runaway points in the battery from expanding into overall thermal runaway, thereby improving the safety of the battery cells.

[0216] In some embodiments, the thickness of the base film in the separator is 7-9 μm.

[0217] In some embodiments, the thickness of the base film in the separator can be selected to be 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, or any range therebetween.

[0218] In some embodiments, the thickness of a single side of the ceramic layer in the separator is 2-4 μm.

[0219] 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.

[0220] In some embodiments, the thickness of a single side of the adhesive layer in the separator is 1-5 μm.

[0221] 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.

[0222] In this application, "thickness" has a well-known meaning in the art and can be measured using methods and instruments known in the art. For example, a high-precision micrometer (such as Mitutoyo 293-100, with an accuracy of 0.1 μm) can be used for testing.

[0223] If the thickness of the adhesive layer is too low, the void space in the diaphragm is small and the adhesion between the diaphragm and the electrode is low. On the one hand, the stress of the membrane layer increases after expansion, and the probability of the membrane layer falling off increases, affecting the cycle life of the battery. On the other hand, the probability of positive-negative short circuit increases, thus affecting the safety performance of the battery. If the thickness of the adhesive layer is too large, it occupies a large amount of battery space, thus 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 take into account the cycle life, safety performance and volume energy density of the battery.

[0224] In some embodiments, the positive electrode film layer is provided with a primer layer in the bottom region near the positive electrode current collector. The primer layer includes a conductive agent and a binder. The conductive agent includes carbon nanotubes and conductive carbon black, and the binder includes polyvinylidene fluoride (PVDF).

[0225] In some embodiments, the primer layer has a thickness of 0.5 μm to 5 μm.

[0226] In some embodiments, the thickness of the primer layer can be selected to be 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 range therebetween.

[0227] The undercoat provided in the embodiments of the present application helps improve the adhesion between the positive electrode film and the positive electrode current collector and alleviates stress concentration at large particles, thereby reducing the probability of positive electrode film shedding and improving the battery's cycling stability. Furthermore, compared to direct contact between the positive electrode current collector and the positive electrode film, the undercoat increases the contact area between the positive electrode film and the positive electrode film, helping to increase the area for electron transfer between the current collector and the positive electrode film, thereby reducing the internal resistance of the electrode sheet and improving the battery's dynamic performance.

[0228] In some embodiments, as Figure 4 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 L0, the size of the shell 50 in the width direction Y is W0, and the size of the shell 50 in the thickness direction Z is H0, wherein 480mm≤L0≤720mm, 100mm≤W0≤150mm; 14mm≤H0≤22mm.

[0229] In some embodiments, L0 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.

[0230] In some embodiments, W0 can be selected as 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, or any range of values ​​therebetween.

[0231] In some embodiments, H0 can be selected as 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, or any range of values ​​therebetween.

[0232] In some embodiments, the length of the housing is L0, 450 mm ≤ L0 ≤ 650 mm.

[0233] When the length dimension L0 of the shell satisfies 450mm≤L0≤650mm, the length of the battery cell is shorter, which helps to shorten the diffusion path of the current and reduce the internal resistance of the electrode, thereby reducing the heat generation of the battery and improving its dynamic performance; in addition, the shorter shell length helps to shorten the diffusion path of the electrolyte during the infiltration process, improve the infiltration rate and uniformity of the electrolyte, further promote the uniformity of lithium ion intercalation and deintercalation during the cycle, alleviate stress concentration, reduce the risk of film shedding, and improve the cycle stability of the battery cell.

[0234] In some embodiments, a length dimension of the housing is L0, 900 mm ≤ L0 ≤ 1300 mm.

[0235] When the length dimension L0 of the housing satisfies 900mm≤L0≤1300mm, the battery cell is longer, which helps reduce the volume ratio of the housing within the battery cell and increase the active material load ratio. At the same time, longer battery cells 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 helping to increase the volume energy density of the battery cell.

[0236] In some embodiments, as Figure 4 As shown, the material of the shell 50 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.

[0237] Applicants have discovered that soft-pack materials are lighter than hard-shell materials like aluminum and steel, potentially further improving the energy density of lithium-containing transition metal phosphate batteries. Furthermore, soft-pack materials have a high degree of elongation, resulting in thinner, lighter, and more flexible shells, which helps improve the space utilization of battery cells and, consequently, their energy density. Furthermore, aluminum's high barrier properties effectively reduce the penetration of water and oxygen into the battery, reducing electrolyte decomposition and oxidation of electrode materials, thereby extending battery life.

[0238] In some embodiments, continue with reference to Figure 4 The shell 50 includes a first sealing area 51, which is arranged at at least one end of the laminated battery cell extending along the width direction; the first sealing area 51 includes a folding structure extending along the length direction, and the folding structure is provided with packaging glue, and the packaging glue is continuously arranged along the length direction and fixes the folding structure.

[0239] The folded edge structure refers to a reinforcement structure formed by folding the packaging area in half. The number of folding times is not limited. As an example, it can be a single folded edge structure folded in half once, or a double folded edge structure folded in half on both sides.

[0240] The SEI film thickens during the positive electrode cycle, resulting in significant rebound and gas production during long cycles. The seal area of ​​the pouch cell is used to seal the electrode assembly, but this seal has limited strength and is easily broken by significant rebound and high gas production in the film.

[0241] In the embodiments of the present application, the first seal region includes a hem structure extending along its length, further enhancing the sealing strength of the first seal region. Compared to discontinuous placement of the encapsulating adhesive along its length, the continuous placement and fixation of the hem structure further enhances the package strength, achieving continuous reinforcement of the seal region along its length and reducing the probability of thickly coated electrodes breaking through the seal region during recycling.

[0242] In some embodiments, the shell 50 includes at least one second sealing area 52, which is arranged at at least one end of the laminated battery core along the length direction of the shell, and the second sealing area 52 is arranged on the tab side of the laminated battery core.

[0243] It is understandable that the positive electrode tab and the negative electrode tab can be arranged on the same side of the laminated battery cell, such as Figure 1 As shown; it can also be set on the opposite side of the laminated battery cell.

[0244] In some embodiments, the battery cell 5 further includes a lead-out member 53, which is connected to the tab of the battery cell. For example, the lead-out member 53 can be welded to the tab. The lead-out member 53 is a conductive member, at least a portion of which is located outside the housing 50. The lead-out member 53 serves as an electrode lead-out terminal of the battery cell 5 and is used to facilitate electrical connection between the battery cell 5 and other battery cells 5 or other components. For example, the lead-out member 53 can be in the form of a sheet.

[0245] Correspondingly, the lead-out member 53 also includes a positive electrode lead-out member and a negative electrode lead-out member. The positive electrode lead-out member is connected to the positive electrode tab, and the negative electrode lead-out member is connected to the negative electrode tab.

[0246] In some embodiments, the second sealing area is arranged on the side of the pole ear, and the pole ear needs to be connected to the lead-out piece. The connection strength between the lead-out piece and the shell material is relatively weak, so that the gas can easily rush out from the second sealing area, which is conducive to achieving directional pressure relief of the battery, reducing the impact on adjacent battery cells during thermal runaway, and improving the overall service life of the battery.

[0247] In some embodiments, a plurality of rubber rings surrounding the laminated battery core along the width direction are provided on the outer periphery of the laminated battery core, and the rubber rings surrounding the width direction are arranged at intervals along the length direction.

[0248] The rubber rings that surround the width of the battery cell and are arranged at intervals in the length direction are beneficial to fixing the position between the electrodes in the battery cell and reducing the probability of the battery cell displacement during battery shaking. It is especially suitable for batteries with a longer length. It can effectively reduce the mutual displacement between the electrodes in the length direction and thus cause lithium plating, which is beneficial to maintaining the stability of the spatial structure inside the battery, thereby not affecting the normal operation of the battery.

[0249] In some embodiments, at 25° C., the capacity of the battery cell is 95 Ah-300 Ah.

[0250] In some embodiments, at 25° C., the capacity of the battery cell is 150 Ah-180 Ah.

[0251] In this application, the capacity of a battery cell has a meaning well known in the art and can be tested using methods known in the art. As an example, at 25°C, charge the battery to 3.65V at a 0.5C charge rate, which corresponds to the nominal capacity of the battery. Then, charge it to 0.05C at a constant voltage of 3.65V and let it rest for 10 minutes. Then, discharge it to 2.5V at a 1C discharge rate and let it rest for 10 minutes. The capacity (C) during the discharge process is calculated using the formula C = I * t, in units of Ah.

[0252] In some embodiments, at 25°C, the capacity of the battery cell may be 95Ah, 100Ah, 105Ah, 107Ah, 110Ah, 115Ah, 120Ah, 125Ah, 130Ah, 135Ah, 140Ah, 145Ah, 150Ah, 155Ah, 160Ah, 161Ah, 162Ah, 163Ah, 164Ah, 165Ah, 170Ah, 175Ah, 180Ah, 182Ah, 185Ah, 190Ah, 200Ah, 210Ah, 220Ah, 230Ah, 240Ah, 250Ah, 270Ah, 280Ah, 290Ah, 300Ah, or any range therebetween.

[0253] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0254] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0255] In some embodiments, the negative electrode film layer includes a negative electrode active material. For example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, and hard carbon. However, this application is not limited to these materials; other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used singly or in combination.

[0256] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0257] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0258] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0259] A second aspect of the present application provides a battery device, comprising the battery cell provided in the first aspect of the present application.

[0260] 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.

[0261] In a third aspect, the present application provides an electrical device that uses a battery device as a power source. The electrical device includes 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. The electrical device can select a battery cell, battery module, or battery pack based on its intended use.

[0262] Figure 5 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.

[0263] A fourth aspect of the present application 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.

[0264] Example

[0265] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0266] Example 1

[0267] (1) Preparation of positive electrode active materials

[0268] Lithium dihydrogen phosphate, ferrous oxalate, a carbon source, titanium dioxide, and vanadium pentoxide are mixed and ground in methanol to obtain a mixed raw material. The ratio of lithium dihydrogen phosphate and ferrous oxalate is such that the molar ratio of lithium to iron is 1.025:1.0; the carbon source includes polyethylene glycol with a weight average molecular weight of 500, polyethylene glycol with a weight average molecular weight of 2000, and polyethylene glycol with a weight average molecular weight of 4000 in a mass ratio of 2:6:2; the particle size of ferrous oxalate is D 10 6.5μm, particle size D 50 The particle size is 62 μm and the particle size D 90 The particle size is 108 μm, the mass content of Fe element in ferrous oxalate is 30.5%, and the mass content of trivalent iron element is 0.03%.

[0269] The mixed raw materials are ball milled several times in a ball mill and demagnetized to obtain a mixed slurry. The grinding times and time are controlled, and the particle size of the mixed slurry after grinding is Dv 50 It is 3.15μm.

[0270] The mixed slurry is spray-dried to obtain a dry precursor powder material, and the dry precursor powder material has a light yellow appearance and a uniform color.

[0271] The precursor powder was placed in a sintering furnace and heated at a rate of 2°C / min from 25°C to 360°C under a nitrogen atmosphere. The temperature was then maintained at this temperature for 3.5 hours. The temperature was then raised at a rate of 5°C / min to a second temperature of 785°C, maintained at this temperature for 10 hours, and then cooled. The mass content of the Ti element was 1050 ppm, and the mass content of the V element was 950 ppm, based on the total mass of the positive electrode active material.

[0272] The obtained material was crushed by air flow pulverization with a classification frequency of 21 Hz and a pulverization pressure of 0.54 MPa to obtain a carbon-coated lithium iron phosphate positive electrode active material.

[0273] The above D10, D50, D90, and Dv50 refer to the data obtained by Malvern laser scattering method.

[0274] (2) Preparation of positive electrode

[0275] The above-mentioned positive electrode active material, conductive agent, and binder polyvinylidene fluoride are mixed in a solvent N-methylpyrrolidone according to a mass ratio of 94.1:1.9:3, and then a dispersant HNBR with a mass ratio of 1% is added. The mixture is fully mixed in a stirring tank, stirred, and dispersed to form a positive electrode slurry. After the stirring process is completed, the positive electrode slurry is transported to the coating process. The conductive agent includes conductive carbon black and multi-walled carbon nanotubes with a mass ratio of 0.9:1. The specific surface area of ​​the conductive carbon black is 80m2 / g, the oil absorption value is 180mL / 100g, the average length of the carbon nanotubes is 20μm, and the specific surface area is 280m 2 / g;

[0276] The positive electrode slurry was extrusion-coated onto aluminum foil and dried, and cold-pressed to obtain a positive electrode film with a single-side thickness H of 105.64 μm and a compaction density of 2.36 g / cm 3 The compaction density here refers to the compaction density of the battery cell when it is fully discharged.

[0277] The positive electrode sheets are striped and punched into specified shapes, and the punched positive electrode sheets are sorted by weight using a weighing sorting machine for stacking by a stacking machine.

[0278] Among them, in the cross section of the positive electrode film along the thickness direction of the electrode, the sphericity area cumulative distribution curve of the particles with a particle size R1 satisfying R1 ≥ 1000 nm, the median of the sphericity L R1A50 The median graphitization degree of the positive electrode film is 0.72; 50 is 1.12; the concentration of graphitization degree C value (C 90 -C 10 ) / C 50 is 0.025; based on the total area of ​​particles in the cross section of the positive electrode film along the thickness direction of the electrode, the area of ​​particles with a particle size R1 that satisfies R1 ≥ 1000 nm accounts for 35.28%; the median B of the positive electrode film coating value B 50 is 0.441; the iron dissolution rate of the positive electrode material is 976 ppm; based on the total area of ​​the cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area of ​​the agglomerated region of the conductive agent accounts for 1.91%; the porosity of the positive electrode film layer is 15.06%; the film resistivity of the positive electrode film layer is 31.0 Ω·cm.

[0279] (2) Preparation of negative electrode sheet

[0280] A mixture of artificial graphite and natural graphite (weight ratio of 1:1), conductive carbon black, binder styrene-butadiene rubber (SBR) and thickener sodium carboxymethyl cellulose (CMC) are mixed evenly in a weight percentage of 96:0.5:2.0:1.5 and deionized water is added. After stirring and dispersion, a negative electrode slurry is obtained. The negative electrode slurry is coated on a base copper foil, and after drying, cold pressing, slitting and sheeting, a negative electrode sheet is obtained.

[0281] The negative electrode sheets are stripped and punched into specified shapes, and the punched negative electrode sheets are sorted by weight using a weighing sorting machine for stacking by a stacking machine.

[0282] (3) Diaphragm

[0283] Polyvinylidene fluoride (PVDF) was dissolved in N-methylpyrrolidone (NMP) and stirred thoroughly. Polyethylene glycol (PEG) was then added as a pore-forming agent and thoroughly stirred to produce a bonding layer solution. This bonding layer solution was then applied to the base film with ceramic layers on both sides. After pre-evaporation at 80°C and drying at 110°C, the solution was immersed in deionized water to dissolve the PEG, resulting in a separator with a porous bonding layer.

[0284] 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.

[0285] (4) Electrolyte

[0286] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), organic solvents dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC) were mixed uniformly.

[0287] Lithium hexafluorophosphate was then added and dissolved in an organic solvent to a concentration of 1.05 mol / L. Vinylene carbonate (VC) was then added and stirred uniformly to obtain the electrolyte of Example 1.

[0288] Among them, based on the total mass of the electrolyte, the mass content of dimethyl carbonate is 26%, the mass content of ethyl methyl carbonate is 43.3%, the mass content of ethylene carbonate is 17.3%, and the mass content of vinylene carbonate is 0.9%.

[0289] (5) Preparation of batteries:

[0290] Use a stacking machine to stack the positive electrode sheets, diaphragms, and negative electrode sheets in order. The diaphragms must be able to isolate the positive and negative electrodes to obtain laminated batteries. The laminated batteries are glued to tightly wrap the batteries. The laminated batteries with glue are placed in an outer package. The outer package is a soft-pack aluminum-plastic film. The aluminum-plastic film is composed of an inner layer of polypropylene, a middle layer of aluminum foil, and an outer layer of nylon. Among them, the aluminum-plastic film outer package is punched and trimmed to obtain the target shape and size. The aluminum-plastic film is then heat-sealed to meet the packaging tension of the aluminum-plastic film ≥25N / 8mm. The battery is vacuum-baked, left to stand, the electrolyte is injected, and the package is then hot-pressed and cold-pressed on the soft-pack battery. The hot pressing temperature is 45°C, the time is 2 minutes, and the pressure is 90kg / cm 2 The cold pressing temperature is 25℃, the time is 2 minutes, and the pressure is 90kg / cm 2 After forming, vacuuming, and trimming, the battery cell is finally obtained. The length of the battery cell is 600 mm, the width is 125 mm, and the thickness is 20 mm.

[0291] The preparation methods of Examples 2-10 are basically the same as those of Example 1, except that the preparation method of the positive electrode active material is adjusted, as follows:

[0292] Example 2

[0293] The preparation method of Example 2 is substantially the same as that of Example 1, except that, in the preparation of the positive electrode active material, the second temperature is adjusted to 765°C.

[0294] Example 3

[0295] The preparation method of Example 3 is substantially the same as that of Example 1, except that, in the preparation of the positive electrode active material, the second temperature is adjusted to 735°C.

[0296] Example 4

[0297] The preparation method of Example 4 is basically the same as that of Example 1, except that, in the preparation of the positive electrode active material, the carbon source is replaced by polyethylene glycol with a weight average molecular weight of 500 and polyethylene glycol with a weight average molecular weight of 2000 in a mass ratio of 2:8.

[0298] Example 5

[0299] The preparation method of Example 5 is substantially the same as that of Example 1, except that, in the preparation of the positive electrode active material, the carbon source is replaced with polyethylene glycol with a weight average molecular weight of 500.

[0300] Example 6

[0301] The preparation method of Example 6 is substantially the same as that of Example 1, except that, in the preparation of the positive electrode active material, the carbon source is replaced with polyethylene glycol with a weight average molecular weight of 2000.

[0302] Example 7

[0303] The preparation method of Example 7 is substantially the same as that of Example 3, except that, in the preparation of the positive electrode active material, the carbon source is replaced by polyethylene glycol with a weight average molecular weight of 500 and glucose in a mass ratio of 2:8.

[0304] Example 8

[0305] The preparation method of Example 8 is basically the same as that of Example 1, except that, when preparing the positive electrode sheet, the coating weight is adjusted, and the parameters such as the hot roller pressing pressure, hot roller temperature, transfer coating speed, and heating temperature before the first hot roller compaction are adaptively adjusted to adjust the compaction density of the positive electrode sheet.

[0306] Example 9

[0307] The preparation method of Example 9 is basically the same as that of Example 1, except that, when preparing the positive electrode sheet, the coating weight is adjusted so that the single-side thickness H of the positive electrode film layer obtained by cold pressing is 119.12 μm; and the thickness of the battery is appropriately adjusted while keeping the number of positive electrode sheets, diaphragms and negative electrode sheets unchanged.

[0308] Example 10

[0309] The preparation method of Example 10 is basically the same as that of Example 1, except that, when preparing the positive electrode sheet, the coating weight is adjusted so that the single-side thickness H of the positive electrode film layer obtained by cold pressing is 71.53 μm; and the thickness of the battery is appropriately adjusted while keeping the number of positive electrode sheets, diaphragms and negative electrode sheets unchanged.

[0310] Comparative Example 1

[0311] The preparation method of Comparative Example 1 is substantially the same as that of Example 7, except that, in the preparation of the positive electrode active material, the carbon source is replaced by glucose.

[0312] Test method:

[0313] 1. Capacity of lithium-ion secondary battery cells

[0314] At 25°C, charge the battery to 3.65V at a charge rate of 0.5C of the nominal capacity, 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.

[0315] 2. Number of cycles until the capacity decays to 80%

[0316] At 25°C, charge the battery to 3.65V at a charge rate of 0.5C of the nominal capacity, then charge at a constant voltage of 3.65V to 0.05C, 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 above charge and discharge is one cycle. The test is stopped until the battery capacity decays to 80% of the nominal capacity, which is recorded as the number of cycles @80% SOH.

[0317] Test results

[0318] The test results of the above embodiments and comparative examples are shown in Table 1.

[0319] Table 1 Preparation parameters of each embodiment and comparative example

[0320]

[0321] From the comparison between Examples 1-10 and Comparative Example 1, it can be seen that the battery cell includes a laminated battery cell, the laminated battery cell includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer includes lithium-containing transition metal phosphate particles with carbon material provided on at least a portion of the surface, and the median value of the graphitization degree C of the positive electrode film layer obtained in the surface scanning mode of the laser microconfocal Raman spectrometer is C. 50 is 0.95-1.20, wherein the graphitization degree C value is 1 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 the battery cell is in a fully discharged state, and the compaction density of the positive electrode sheet is 2.3 g / cm 3 -2.6g / cm 3 , the battery cells help to improve the cycle life of the battery during long cycles while maintaining good capacity.

[0322] From the comparison between Example 1, Example 4-6 and Example 7, it can be seen that in the cumulative distribution curve of the graphitization degree C value of the positive electrode film layer obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the median value of the graphitization degree C is 50 It can further be selected to be 1.01-1.13, which helps to further improve the cycle life of the battery cell during a long cycle process.

[0323] From the comparison between Examples 1-10 and Comparative Example 1, it can be seen that in the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 The value is 0.01-0.05, which helps to further improve the cycle life of the battery cell during long cycles.

[0324] As can be seen from Examples 1-3, in the cross section of the positive electrode film along the thickness direction of the positive electrode sheet, the cumulative distribution curve of the spherical area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm is L R1A50 The α / β ratio is within the range of 0.67-0.75, and the battery cell has a good cycle life in a long cycle process.

[0325] As can be seen from Examples 1-9, when the thickness H of the positive electrode film layer on one side is in the range of 70 μm-120 μm, the battery cell helps to improve the cycle life of the battery during long cycles while maintaining good capacity.

[0326] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, characterized in that: The laminated battery cell includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector. The positive electrode film layer includes lithium-containing transition metal phosphate particles with carbon material provided on at least a portion of the surface. The thickness of a single side of the positive electrode film layer is denoted as H, and H is 70 μm-120 μm. 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 0.95-1.20, Among them, 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 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 .

2. 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 It is 1.01-1.

13.

3. The battery cell according to claim 1, wherein: In the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 It is 0.01-0.

05.

4. The battery cell according to claim 3, characterized in that In the cumulative distribution curve of the graphitization degree C value of the positive electrode film obtained in the surface scanning mode of the laser microconfocal Raman spectrometer, the concentration of the C value (C 90 -C 10 ) / C 50 It is 0.02-0.

04.

5. The battery cell according to claim 1, characterized in that Based on the total area of ​​particles in the cross section of the positive electrode film along the thickness direction of the electrode sheet, the area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm accounts for 12%-50%.

6. The battery cell according to claim 5, characterized in that Based on the total area of ​​particles in the cross section of the positive electrode film along the thickness direction of the electrode sheet, the area of ​​particles with a particle size R1 satisfying R1 ≥ 1000 nm accounts for 12%-40%.

7. The battery cell according to claim 5, 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 particle size R1 that satisfies R1 ≥ 1000 nm is R1A1 50 is 0.6-0.

8.

8. The battery cell according to claim 7, 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 particle size R1 that satisfies R1 ≥ 1000 nm is R1A1 50 is 0.65-0.

75.

9. The battery cell according to claim 7, 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 particle size R1 that satisfies R1 ≥ 1000 nm is R1A1 50 is 0.67-0.

75.

10. 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 B of the coating value B is 50 0.30-0.60, The wrapping value B is I P / I D , where I P Indicates that the Raman spectrum is at 948 ± 100 cm -1 The intensity of the P peak at I D Indicates that the Raman spectrum is at 1350±100cm -1 The D peak intensity at .

11. The battery cell according to claim 1, characterized in that The lithium-containing transition metal phosphate particles 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.

12. The battery cell according to claim 1, wherein The positive electrode film layer includes a positive electrode material, and the iron dissolution rate of the positive electrode material is 658ppm-1921ppm.

13. The battery cell according to claim 12, characterized in that The iron dissolution rate of the positive electrode material is 658ppm-1485ppm.

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

15. The battery cell according to claim 14, characterized in that Based on the total mass of the lithium-containing transition metal phosphate particles, the mass content of titanium element is 1000 ppm-3000 ppm.

16. The battery cell according to claim 1, characterized in that 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 500 ppm-5000 ppm.

17. The battery cell according to claim 16, characterized in that Based on the total mass of the lithium-containing transition metal phosphate particles in the positive electrode film layer, the mass content of vanadium element is 500ppm-3000ppm.

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

19. The battery cell according to claim 1, characterized in that The resistivity of the positive electrode film layer is 10Ω·cm-35Ω·cm.

20. The battery cell according to claim 1, characterized in that The thickness of the positive electrode film layer on one side is recorded as H, and H is 90 μm-120 μm.

21. The battery cell according to claim 1, characterized in that The thickness of the positive electrode film layer on one side is recorded as H, and H is 100 μm-120 μm.

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

23. 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.

24. The battery cell according to claim 1, characterized in that Based on the mass of the positive electrode film layer, the mass content of the dispersant is 0.5%-2%.

25. 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 area of ​​the agglomerated region of the conductive agent accounts for 0.5%-2.5%.

26. The battery cell according to claim 25, characterized in that Based on the total area of the cross-section of the positive electrode film layer along the thickness direction of the electrode sheet, the area ratio of the agglomeration region of the conductive agent is 1.5% - 2.5%.

27. The battery cell according to claim 25, 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.

28. The battery cell according to claim 27, characterized in that The conductive agent further includes conductive carbon black.

29. The battery cell according to claim 25, characterized in that The agglomeration region of the conductive agent includes carbon nanotubes and conductive carbon black.

30. The battery cell according to claim 18, wherein 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 < C1 ≤ 2.5%.

31. The battery cell according to claim 1, characterized in that The battery cell further includes a separator disposed between the positive electrode sheet and the negative electrode sheet. The separator includes a base film, a ceramic layer disposed on both sides of the base film, and a bonding layer disposed on the side of at least one of the ceramic layers away from the base film. The bonding layer is a continuous layer with a porous structure, and the bonding layer includes a vinylidene fluoride-based polymer.

32. The battery cell according to claim 31, characterized in that The separator satisfies at least one of the following conditions: (1) The thickness of the base film is 7 - 9 μm; (2) The thickness of the ceramic layer on one side is 2 - 4 μm; (3) The thickness of the bonding layer on one side is 1 - 5 μm.

33. The battery cell according to claim 1, characterized in that The battery cell includes a housing, and at least one of the laminated battery cells 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, where 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 35, wherein (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 disposed at at least one end of the laminated battery cell extending in the width direction; the first sealing area includes a folded edge structure extending in the length direction, and a packaging adhesive is disposed on the folded edge structure. The packaging adhesive is continuously disposed 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 disposed along the length direction of the housing at at least one end of the laminated battery cell. The second sealing area is disposed on the tab side of the laminated battery cell.

37. The battery cell according to claim 36, wherein The soft package material includes one or more of aluminum, polypropylene, polybutylene terephthalate, polybutylene succinate, nylon, polyethylene terephthalate, and polyethylene.

38. The battery cell according to claim 1, characterized in that A plurality of rubber rings surrounding in the width direction are disposed on the outer periphery of the laminated battery cell, and the rubber rings surrounding in the width direction are spaced apart in the length direction.

39. The battery cell according to claim 1, wherein: At 25 °C, the capacity of the battery cell is 105 Ah - 190 Ah.

40. The battery cell according to claim 39, characterized in that At 25 °C, the capacity of the battery cell is 150 Ah - 190 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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