Battery monomer, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device, and belongs to the technical field of batteries. The battery monomer provided by the invention comprises a positive electrode plate, the positive electrode plate comprises a positive electrode current collector, a positive electrode film layer arranged on at least one side of the positive electrode current collector, and a bottom coating layer arranged between the positive electrode current collector and the positive electrode film layer on at least one side, the positive electrode film layer comprises a positive electrode active material, and the bottom coating layer comprises a negative electrode active material. The positive electrode active material comprises a lithium-containing transition metal oxide, and the volume distribution particle size Dv90 of particles in the positive electrode film layer is greater than or equal to 16 [mu] m; and the volume distribution particle size Dv99 of particles in the bottom coating is less than or equal to 15 microns. The battery monomer provided by the invention has excellent energy density, safety performance and cycle life.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery device and an electrical device. Background Art

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. As the market pursues the electrical performance of battery cells, the processing difficulty of battery cells increases and the yield rate decreases, resulting in the safety performance and service life of battery cells failing to meet expectations, limiting the further application of batteries. How to take both into account at the same time has become an urgent problem to be solved in this field. Summary of the invention

[0003] The present application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell, a battery device and an electric device, wherein the battery cell has excellent energy density, safety performance and cycle life.

[0004] An embodiment of the first aspect of the present application provides a battery cell, wherein the battery cell includes a positive electrode plate, the positive electrode plate includes a positive electrode collector, a positive electrode film layer arranged on at least one side of the positive electrode collector, and an undercoat layer arranged between the positive electrode collector and at least one side of the positive electrode film layer, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing transition metal oxide, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16μm, and can be optionally 16μm-26μm; the volume distribution particle size Dv99 of the particles in the undercoat layer is less than or equal to 15μm, and can be optionally 5μm-15μm.

[0005] The positive electrode film layer of the battery cell provided in the embodiment of the present application includes a lithium-containing transition metal oxide, and the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16μm to improve the energy density of the battery cell. At the same time, a base coating layer with particles Dv99 less than or equal to 15μm is arranged between the positive electrode film layer and the positive electrode collector to buffer the squeezing of the current collector by large particles in the positive electrode film layer during the slicing process, reduce the probability of large-sized burrs during the electrode sheet cutting process, and improve the yield rate in the electrode sheet cutting process while maintaining the high energy density of the battery cell, thereby meeting the performance and efficiency requirements.

[0006] In any embodiment, the volume distribution particle size Dv50 of the particles in the base coating layer is 0.4 μm-2.0 μm, optionally 0.4 μm-1.5 μm, and further optionally 0.4 μm-0.8 μm.

[0007] The base coating layer uses small particle materials with a particle size that meets the above range, which further buffers the extrusion of large particles in the positive electrode film layer on the current collector during slicing, reduces the probability of large-size burrs, and at the same time can improve the adhesion between the positive electrode current collector and the base coating layer, effectively preventing powder loss, aluminum leakage, etc. when the electrode sheets are cut, thereby improving the safety performance of the battery.

[0008] In any embodiment, the undercoat layer comprises a lithium-containing transition metal phosphate, wherein the general formula of the lithium-containing transition metal phosphate comprises Li m Q q Fe x P y O j , 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, 0.6≤m≤1.15, 0≤x≤1, 0.95≤y≤1, 3.5≤j≤4, and 0≤q≤1.

[0009] Lithium-containing transition metal phosphates are generally polyanion active materials with an olivine structure. Compared with lithium-containing transition metal oxides, they have good thermodynamic thermal stability and can reduce high-temperature oxygen release. They also have lower particle hardness and smaller particle distribution. Using them as a base coating can not only alleviate the extrusion of the current collector and improve the burr phenomenon, but also improve the safety performance and service life of the battery cell.

[0010] In any embodiment, the lithium-containing transition metal phosphate includes Mn element, and based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar proportion of Mn element in the lithium-containing transition metal phosphate is 10%~70%, and can be optionally 30%~50%.

[0011] Studies have shown that the voltage platform of conventional lithium iron phosphate materials is too low (~3.2V) compared to lithium-containing transition metal oxides, which lowers the voltage platform of the battery cell when the battery is working, making it difficult to fully utilize the gram capacity of lithium iron phosphate. Introducing the Mn element into lithium iron phosphate can effectively increase the voltage platform of lithium iron phosphate (~3.7V), adapting it to the voltage window of lithium-containing transition metal oxides in the positive electrode film layer, which is conducive to the utilization of the material's gram capacity, allowing the bottom coating to reduce the probability of burrs while reducing the negative impact on the battery's energy density.

[0012] In any embodiment, the base coating layer includes lithium manganese iron phosphate and one or more of its doped modified materials and coated modified materials. Based on the total molar number of Mn element and Fe element, the molar proportion of Mn element is 10%~70%, and can be optionally 30%~50%.

[0013] Introducing Mn element into lithium iron phosphate, the active material of the bottom coating layer, can increase the voltage platform of the active material and adapt to the voltage platform window of lithium-containing transition metal oxides, thereby increasing the energy density of the battery cell; however, Mn ions have a large ionic radius, are prone to crystal structure distortion, and have poor stability, resulting in a decrease in cycle life. Therefore, controlling the molar proportion of the Mn element to meet the above range can improve the energy density of the battery while also improving the cycle life of the battery.

[0014] In any embodiment, the lithium-containing transition metal oxide includes nickel element, and the molar ratio of the nickel element in the lithium-containing transition metal oxide is 80%-96% based on the total molar number of transition metal in the lithium-containing transition metal oxide.

[0015] Lithium-containing transition metal oxides with a molar proportion of 80%-96% nickel have high gram capacity, which is conducive to further improving the energy density of battery cells, but this will further increase the hardness of particles in the positive electrode film layer, increase the degree of compression of large particles in the positive electrode film layer on the current collector, and make it easy to produce large-sized burrs during the cutting process of the positive electrode sheet. The technical solution in the embodiment of the present application is particularly suitable for the positive electrode sheet, which further improves the high energy density of the battery while improving the yield rate during the cutting process of the electrode sheet, meeting the performance and efficiency requirements.

[0016] In any embodiment, the volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, and the peak position difference is greater than or equal to 3 μm and less than or equal to 8 μm.

[0017] In any embodiment, in the volume distribution curve of particles in the positive electrode film layer, the double peaks are located at 1 μm-6 μm and 6 μm-14 μm respectively.

[0018] The volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, indicating that the positive electrode film layer includes large particles and small particles of different sizes. Filling the gaps between large particles with small particles is beneficial to improving the compaction density of the electrode sheet, thereby further improving the energy density of the battery.

[0019] In any embodiment, the particles in the positive electrode film layer include lithium-containing transition metal oxide polycrystalline particles and lithium-containing transition metal oxide single crystal particles.

[0020] In any embodiment, the volume distribution particle size Dv99 of the polycrystalline particles is 18 μm-30 μm, and can be 20 μm-30 μm; and / or the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-14 μm, and can be 6 μm-12 μm.

[0021] In any embodiment, the volume distribution particle size Dv99 of the single crystal particles is 6 μm-15 μm, and can be 6 μm-13 μm; and / or the volume distribution particle size Dv50 of the single crystal particles is 1 μm-6 μm, and can be 1 μm-4 μm.

[0022] The combination of polycrystalline particles and single crystal particles that meet the above-mentioned particle size range is beneficial to improving the particle grading, achieving close stacking of particles in the positive electrode film layer, and further increasing the compaction density of the electrode sheet, thereby increasing the energy density of the battery.

[0023] In any embodiment, the mass ratio of the polycrystalline particles to the single crystal particles is 5:5-9:1, and can be optionally 6:4-8:2.

[0024] Controlling the mass ratio of polycrystalline particles and single crystal particles to meet the above range is beneficial to improving the compaction density of the electrode, so that the battery has excellent energy density.

[0025] In any embodiment, the lithium-containing transition metal oxide comprises Li a1 Ni x1 Co y1 M1 z1 M2 w1 O 2-b1 , wherein M1 includes one or more of Mn and Al, and M2 includes one or more of Zr, B, Mg, Ti, W, Mo, Nb, Ta, Sr, Sb, and K; 0.8≤a1≤1.2, 0≤x1≤1, 0≤y1≤1, 0≤z1≤1, 0≤w1≤0.1, and -0.1≤b1≤0.1.

[0026] When the positive electrode film layer includes the above-mentioned type of lithium-containing transition metal oxide, the gram capacity of the positive electrode active material can be further increased, thereby further improving the energy density of the battery cell.

[0027] In any embodiment, the thickness of the primer layer on one side is 5 μm-20 μm, and can be 10-15 μm.

[0028] When the thickness of the bottom coating on one side is within the above range, it can reduce the contact between large particles of the positive electrode active material and the current collector, reduce the probability of large-sized burrs on the pole piece during cutting, and further improve the safety performance of the battery cell; at the same time, it can reduce the deterioration of pole piece compression and battery capacity loss caused by adding the bottom coating, so that the battery cell still has a high energy density.

[0029] In any embodiment, the thickness of the positive electrode film layer on one side is 20 μm-70 μm.

[0030] The thinning of the positive electrode film layer is conducive to reducing the diffusion path of lithium ions and improving the dynamic performance of battery cells; however, with the thinning of the positive electrode film layer, in order to make the battery have a high energy density, the compaction density of the pole piece is further increased, which makes the current collector more severely squeezed by large particles during slicing, and the probability of burrs is higher. At the same time, with the thinning of the positive electrode film layer and the positive electrode sheet, the burr control level of large-size specifications is tightened simultaneously, and the burrs are more likely to protrude from the edge of the positive electrode film layer, exacerbating the safety hazards of the burr problem.

[0031] In any embodiment, the thickness of the positive electrode current collector is 5 μm-20 μm, and can be 7 μm-15 μm.

[0032] The positive electrode current collector does not contribute to the capacity of the battery, and its thinning is conducive to making room for the positive electrode active material and improving the energy density of the battery cell. However, the thinning of the positive electrode current collector reduces its ability to withstand large particle extrusion during the slitting process, and the burr phenomenon is more serious. The thickness of the positive electrode current collector within the above range is conducive to improving the yield rate during the electrode cutting process while maintaining the high energy density of the battery cell, meeting the performance and efficiency requirements.

[0033] In any embodiment, when the battery cell is fully charged, the compaction density of the positive electrode sheet is 3.4 g / cm 3 -3.7g / cm 3 .

[0034] The compaction density of the positive electrode sheet within the above range is beneficial to maintaining the high energy density of the battery cell while improving the yield rate in the electrode sheet cutting process, thereby meeting the performance and efficiency requirements.

[0035] In any embodiment, the bonding strength between the primer layer and the positive electrode current collector is 5 N / m-75 N / m, and can be 5 N / m-50 N / m.

[0036] The bonding strength between the primer layer and the positive electrode current collector within the above range is beneficial to improving the aluminum leakage of the pole piece and improving the cycle life of the battery.

[0037] In any embodiment, the thermal decomposition temperature of the positive electrode plate is 225°C-255°C, and can be optionally 227°C-250°C.

[0038] In any embodiment, after the positive electrode sheets are cut at a cutting speed of 0.5 m / s to obtain at least 2000 sheets, the proportion of positive electrode sheets with burrs is 0%-0.05%.

[0039] In any embodiment, the volume energy density of the battery cell is 600Wh / L-720Wh / L.

[0040] An embodiment of a second aspect of the present application provides a battery device, which includes the battery cell in the above embodiment.

[0041] An embodiment of the third aspect of the present application provides an electrical device, which includes the battery cell in the above embodiment, and the battery cell is used to provide electrical energy.

[0042] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0044] Figure 1 This is a cross-sectional polished electron microscope morphology image of a positive electrode sheet in one embodiment of the present application; Figure 2 This is a cross-sectional morphology diagram of a positive electrode sheet cut along the thickness direction in the comparative example of the present application; Figure 3 is a cross-sectional morphology diagram of a positive electrode sheet cut along the thickness direction in one embodiment of the present application; Figure 4 is a comparison diagram of differential thermal analysis curves of the positive electrode sheet in one embodiment of the present application; Figure 5 is a particle size distribution curve diagram of the positive electrode film layer of the positive electrode sheet in one embodiment of the present application; Figure 6 is a schematic diagram of a battery cell according to an embodiment of the present application; Figure 7 yes Figure 6 An exploded view of a battery cell according to an embodiment of the present application is shown; Figure 8 is a schematic diagram of a battery module according to an embodiment of the present application; Fig. 9 is a schematic diagram of a battery pack according to an embodiment of the present application; Fig.10 yes Fig. 9 An exploded view of a battery pack according to an embodiment of the present application is shown; Fig.11 FIG. 1 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0045] Description of reference numerals: 11 positive electrode sheet; 111 positive electrode current collector; 112 bottom coating; 113 positive electrode film layer 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0046] Hereinafter, the battery cells, battery devices and power devices of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are 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 descriptions 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.

[0047] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a 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 a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it 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.

[0048] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0049] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0050] If there is no special explanation, all steps of the present application can 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.

[0051] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0052] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0053] As the market demands for the endurance of electrical devices increase, increasing the volume energy density of battery cells has become a common pursuit of the industry. The increase in the volume energy density of battery cells often requires an increase in the compaction density of the pole pieces to increase the load of active materials per unit volume. However, researchers have found that pole pieces with high compaction density are prone to large-sized burrs during the cutting process. Pole pieces with large-sized burrs are prone to penetrate the diaphragm after the electrode assembly, causing abnormal self-discharge of the battery cell, and even causing short circuit failure of the battery cell, thereby affecting the safety performance and life of the battery, and failing to meet the use requirements of the battery cell.

[0054] Based on the above problems, the first embodiment of the present application provides a battery cell. Figure 1 As shown, the battery cell includes a positive electrode plate 11, the positive electrode plate 11 includes a positive electrode collector 111, a positive electrode film layer 113 arranged on at least one side of the positive electrode collector, and an undercoat layer 112 arranged between the positive electrode collector and the positive electrode film layer on at least one side, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a lithium-containing transition metal oxide, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16μm, and can be optionally 16μm-26μm; the volume distribution particle size Dv99 of the particles in the undercoat layer is less than or equal to 15μm, and can be optionally 5μm-15μm.

[0055] In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16μm. In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is 16μm-26μm. In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer can be selected as 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, or any range between any two of the foregoing values. It can be understood that the particles in the positive electrode film layer mainly come from the positive electrode active material particles.

[0056] In some embodiments, the volume distribution particle size Dv99 of the particles in the primer layer is less than or equal to 15 μm. In some embodiments, the volume distribution particle size Dv99 of the particles in the primer layer is 5 μm-15 μm. In some embodiments, the volume distribution particle size Dv99 of the particles in the primer layer is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any range between any two of the foregoing values.

[0057] When used in this article, the term "burr" refers to a metal protrusion or protrusion extending outward from the current collector in accordance with the IEEE1725 battery cell safety performance review and testing standard; the extension direction can be in any direction, such as the thickness direction or the pole piece plane direction, and the causes of its occurrence include but are not limited to cutting, tearing, etc.

[0058] When used in this article, the terms "volume distribution particle size Dv90, Dv99, Dv50" refer to the particle sizes corresponding to the cumulative volume distribution percentages of the material reaching 90%, 99%, and 50%, respectively. The values ​​can be measured using conventional instruments and methods in the art. For example, they can be measured with reference to GB / T19077-2016 using an instrument that uses a particle size distribution laser diffraction method (such as the Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK).

[0059] The volume distribution particle size Dv90 of the particles in the positive electrode film layer and the volume distribution particle size Dv99 of the particles in the undercoat layer can be tested by any known method in the art. As an example, powder is scraped from the positive electrode film layer or the undercoat layer and tested in the manner described above.

[0060] Lithium-containing transition metal oxides are an important class of positive electrode materials for lithium-ion batteries, characterized by transition metals (such as cobalt, nickel, manganese, etc.) combined with oxygen to form a layered or spinel structure. As an example, they include but are not limited to lithium cobalt oxide ( , LCO), lithium nickel oxide ( , LNO), ternary materials lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium-rich manganese-based oxide.

[0061] In order to improve the compaction density of the electrode, it is necessary to increase the proportion of large particles in the electrode film layer to achieve dense stacking of the film layer through the grading theory. However, during the slicing process, the cutter squeezes the large particles, which will cause the large particles to squeeze the current collector, causing the current collector to break due to extrusion deformation rather than cutting, resulting in a large number of large-sized burrs, such as Figure 2 As shown, the safety performance of the battery is affected. Lithium-containing transition metal oxides have high capacity and are the preferred material for high energy density batteries. However, they also have high hardness. The large particles in lithium-containing transition metal oxides will make the burr problem more significant while improving the battery energy density.

[0062] The battery cell positive electrode film provided in the embodiment of the present application includes a lithium-containing transition metal oxide, and the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16 μm to improve the energy density of the battery cell. At the same time, a primer layer with a particle size Dv99 less than or equal to 15 μm is provided between the positive electrode film layer and the positive electrode current collector to buffer the squeezing of the large particles in the positive electrode film layer on the current collector during the slicing process, thereby reducing the probability of large-sized burrs being generated during the electrode sheet cutting process, such as Figure 3 As shown, the yield rate in the electrode cutting process is improved while maintaining the high energy density of the battery cell, meeting the performance and efficiency requirements.

[0063] In some embodiments, the volume distribution particle size Dv50 of the particles in the primer layer is 0.4 μm-2.0 μm. In some embodiments, in some embodiments, the volume distribution particle size Dv50 of the particles in the primer layer is 0.4 μm-1.5 μm.

[0064] In some embodiments, the volume distribution particle size Dv50 of the particles in the base coating is 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, or any range between any two of the foregoing values.

[0065] The base coating layer uses small particle materials with a particle size that meets the above range, which further buffers the extrusion of large particles in the positive electrode film layer on the current collector during slicing, reduces the probability of large-size burrs, and at the same time can improve the adhesion between the positive electrode current collector and the base coating layer, effectively preventing powder loss, aluminum leakage, etc. when the electrode sheets are cut, thereby improving the safety performance of the battery.

[0066] In some embodiments, the undercoat layer includes a lithium-containing transition metal phosphate, wherein the lithium-containing transition metal phosphate has a general formula including Li m Q q Fe x Py O j , 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, 0.6≤m≤1.15, 0≤x≤1, 0.95≤y≤1, 3.5≤j≤4, and 0≤q≤1.

[0067] In some embodiments, m can be 0.6, 0.65, 0.70, 0.75, 0.8, 0.85, 0.9, 0.95, 1.00, 1.05, 1.10, 1.15, or any range between any two of the foregoing values. In some embodiments, x can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or any range between any two of the foregoing values. In some embodiments, y can be 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, or any range between any two of the foregoing values. In some embodiments, j can be 3.50, 3.55, 3.60, 3.65, 3.70, 3.75, 3.80, 3.85, 3.90, 3.95, 4.00, or any range between any two of the foregoing values. In some embodiments, q can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or any range between any two of the foregoing values.

[0068] Lithium-containing transition metal phosphates are generally polyanion active materials with an olivine structure. Compared with lithium-containing transition metal oxides, they have good thermodynamic thermal stability and can reduce high-temperature oxygen release. They also have lower particle hardness and smaller particle distribution. Using them as a base coating can not only alleviate the extrusion of the current collector and improve the burr phenomenon, but also improve the safety performance and service life of the battery cell.

[0069] In some embodiments, the lithium-containing transition metal phosphate includes Mn element.

[0070] Studies have shown that the voltage platform of conventional lithium iron phosphate materials is too low (~3.2V) compared to lithium-containing transition metal oxides, which lowers the voltage platform of the battery cell when the battery is working, making it difficult to fully utilize the gram capacity of lithium iron phosphate. Introducing the Mn element into lithium iron phosphate can effectively increase the voltage platform of lithium iron phosphate (~3.7V), adapting it to the voltage window of lithium-containing transition metal oxides in the positive electrode film layer, which is conducive to the utilization of the material's gram capacity, allowing the bottom coating to reduce the probability of burrs while reducing the negative impact on the battery's energy density.

[0071] In some embodiments, based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar ratio of the Mn element in the lithium-containing transition metal phosphate is 10% to 70%, and can be optionally 30% to 50%.

[0072] In some embodiments, based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar ratio of the Mn element in the lithium-containing transition metal phosphate is 10%, 20%, 30%, 40%, 50%, 60%, 70%, or any range between any two of the foregoing values.

[0073] Introducing Mn element into lithium iron phosphate, the active material of the bottom coating layer, can increase the voltage platform of the active material and adapt to the voltage platform window of lithium-containing transition metal oxides, thereby increasing the energy density of the battery cell; however, Mn ions have a large ionic radius, are prone to crystal structure distortion, and have poor stability, resulting in a decrease in cycle life. Therefore, controlling the molar proportion of the Mn element to meet the above range can improve the energy density of the battery while also improving the cycle life of the battery.

[0074] In some embodiments, the undercoat layer includes lithium manganese iron phosphate and one or more of its doped modified materials and coated modified materials, and the molar proportion of the Mn element is 10% to 70% based on the total molar number of the Mn element and the Fe element, and can be 30% to 50%. In some embodiments, the molar proportion of the Mn element is 10%, 20%, 30%, 40%, 50%, 60%, 70%, or any range between any two of the foregoing values ​​based on the total molar number of the Mn element and the Fe element.

[0075] In some embodiments, the lithium-containing transition metal oxide includes nickel element, and the molar ratio of the nickel element in the lithium-containing transition metal oxide is 80%-96% based on the total molar number of transition metal in the lithium-containing transition metal oxide.

[0076] In some embodiments, based on the total molar number of transition metal in the lithium-containing transition metal oxide, the molar proportion of nickel in the lithium-containing transition metal oxide can be selected to be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, or any range between any two of the foregoing numerical ranges.

[0077] When used in this article, based on the total molar number of transition metals in the lithium-containing transition metal oxide, the molar proportion of nickel in the lithium-containing transition metal oxide can be determined by instruments and methods known in the art. As an example, it can be measured by the following method: take 0.5g of the material to be tested, soak it in 100 mL of aqua regia solution for digestion, the digestion temperature is 50°C, and then take the completely dissolved solution for inductively coupled plasma (ICP) testing to detect the content of transition metals (such as Ni, Co, Mn ions) in the solution, and divide the molar number of nickel elements by the total molar number of transition metal elements as the molar proportion of nickel elements in the lithium-containing transition metal oxide based on the total molar number of transition metals in the lithium-containing transition metal oxide.

[0078] Lithium-containing transition metal oxides with a molar proportion of 80%-96% nickel have high gram capacity, which is conducive to further improving the energy density of battery cells, but this will further increase the hardness of particles in the positive electrode film layer, increase the degree of compression of large particles in the positive electrode film layer on the current collector, and make it easy to produce large-sized burrs during the cutting process of the positive electrode sheet. The technical solution in the embodiment of the present application is particularly suitable for the positive electrode sheet, which further improves the high energy density of the battery while improving the yield rate during the cutting process of the electrode sheet, meeting the performance and efficiency requirements.

[0079] In some embodiments, the volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, and the peak position difference is greater than or equal to 3 μm and less than or equal to 8 μm.

[0080] In some embodiments, the volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, and the peak position difference is 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or any range between any two of the aforementioned values.

[0081] In some embodiments, in the volume distribution curve of particles in the positive electrode film layer, the double peaks are located at 1 μm-6 μm and 6 μm-14 μm, respectively.

[0082] In some embodiments, in the volume distribution curve of the particles in the positive electrode film layer, one of the double peaks is located at 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, or any range between any two of the aforementioned values; the other peak of the double peak is located at 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or any range between any two of the aforementioned values.

[0083] The volume distribution curve of the particles in the positive electrode film layer can refer to GB / T19077-2016 and be detected using the test method described above. The volume distribution curve of the particles in the positive electrode film layer in one embodiment of the present application is as follows: Figure 5The volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, indicating that the positive electrode film layer includes large particles and small particles of different sizes. Filling the gaps between large particles with small particles is beneficial to improving the compaction density of the electrode sheet, thereby further improving the energy density of the battery.

[0084] In some embodiments, the particles in the positive electrode film layer include polycrystalline particles of lithium-containing transition metal oxides and single crystal particles of lithium-containing transition metal oxides.

[0085] When used in this article, the term "polycrystalline particles" refers to agglomerates of single crystal particles. The agglomeration here is a hard agglomeration caused by chemical bonding of single crystal particles, which makes the polycrystalline particles have more clear grain boundaries and inconsistent atomic arrangement orientation. After cutting the cross section of the polycrystalline particles, it can be seen that the polycrystalline particles are formed by the agglomeration of many single crystal particles.

[0086] As used herein, the term "single crystal particle" refers to the smallest unit of a particle within a certain observation range. The interior of a single crystal particle may include defects of any form, but no smaller particles can be defined therein. It is understood that the single crystal particles described herein do not necessarily mean that there are no grain boundaries inside the single crystal, and that atoms, molecules or ions are continuously and consistently arranged in a three-dimensional space. Instead, it means that it is impossible to define smaller particles inside the single crystal through grain boundaries at a certain observation scale. The single crystal particles referred to herein refer to particles that exist in the pole piece in the form of single crystal particles, and do not include single crystal particles that constitute polycrystalline particles.

[0087] In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is 18 μm-30 μm. In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is 20 μm-30 μm. In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any range between any two of the foregoing values.

[0088] In some embodiments, the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-14 μm. In some embodiments, the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-12 μm. In some embodiments, the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or any range between any two of the foregoing values.

[0089] In some embodiments, the volume distribution particle size Dv99 of the single crystal particles is 6 μm-15 μm. In some embodiments, the volume distribution particle size Dv99 of the single crystal particles is 6 μm-13 μm. In some embodiments, the volume distribution particle size Dv99 of the single crystal particles is 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any range between any two of the foregoing values.

[0090] In some embodiments, the volume distribution particle size Dv50 of the single crystal particles is 1 μm-6 μm. In some embodiments, the volume distribution particle size Dv50 of the single crystal particles is 1 μm-4 μm. In some embodiments, the volume distribution particle size Dv50 of the single crystal particles is 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or any range between any two of the foregoing values.

[0091] The combination of polycrystalline particles and single crystal particles that meet the above-mentioned particle size range is beneficial to improving the particle grading, achieving close stacking of particles in the positive electrode film layer, and further increasing the compaction density of the electrode sheet, thereby increasing the energy density of the battery.

[0092] In some embodiments, the mass ratio of the polycrystalline particles to the single crystal particles is 5:5-9:1. In some embodiments, the mass ratio of the polycrystalline particles to the single crystal particles is 6:4-8:2. In some embodiments, the mass ratio of the polycrystalline particles to the single crystal particles is 5:5, 6:4, 7:3, 8:2, 9:1, or any range between any two of the foregoing values.

[0093] When used in this article, the mass ratio of polycrystalline particles and single crystal particles can be determined by the following method: take a prepared positive electrode sheet, or a positive electrode sheet disassembled from a battery, and perform a CP-SEM test. Randomly select a number of points for shooting, and the number of points is ≥10, which can be 10, 20, 50, 100, etc. The area ratio of the polycrystalline particles and single crystal particles in the captured image to the size of the positive electrode film layer is calculated, and the average value is obtained. The area ratio between polycrystalline particles and single crystal particles can be equivalent to the mass ratio of polycrystalline particles to single crystal particles.

[0094] Controlling the mass ratio of polycrystalline particles and single crystal particles to meet the above range is beneficial to improving the compaction density of the electrode, so that the battery has excellent energy density.

[0095] In some embodiments, the lithium-containing transition metal oxide includes Li a1 Ni x1 Co y1M1 z1 M2 w1 O 2-b1 , wherein M1 includes one or more of Mn and Al, and M2 includes one or more of Zr, B, Mg, Ti, W, Mo, Nb, Ta, Sr, Sb, and K; 0.8≤a1≤1.2, 0≤x1≤1, 0≤y1≤1, 0≤z1≤1, 0≤w1≤0.1, and -0.1≤b1≤0.1.

[0096] In some embodiments, a1 can be 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, or any range between any two of the foregoing values. In some embodiments, x1 can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, or any range between any two of the foregoing values. In some embodiments, y1 can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range between any two of the foregoing values. In some embodiments, z1 can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range between any two of the foregoing values. In some embodiments, w1 can be 0, 0.02, 0.04, 0.06, 0.08, 0.1, or any range between any two of the foregoing values. In some embodiments, b1 can be -0.1, -0.05, 0, 0.05, 0.1, or any range between any two of the foregoing values.

[0097] When the positive electrode film layer includes the above-mentioned type of lithium-containing transition metal oxide, the gram capacity of the positive electrode active material can be further increased, thereby further improving the energy density of the battery cell.

[0098] In some embodiments, the thickness of the primer layer on one side is 5 μm-15 μm, and can be 10 μm-15 μm. In some embodiments, the thickness of the primer layer on one side is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any range between any two of the foregoing values.

[0099] The thickness of the primer layer on one side can be observed and measured by scanning electron microscopy on the cross section of the positive electrode sheet.

[0100] When the thickness of the bottom coating on one side is within the above range, it can reduce the contact between large particles of the positive electrode active material and the current collector, reduce the probability of large-sized burrs on the pole piece during cutting, and further improve the safety performance of the battery cell; at the same time, it can reduce the deterioration of pole piece compression and battery capacity loss caused by adding the bottom coating, so that the battery cell still has a high energy density.

[0101] In some embodiments, the thickness of the positive electrode film layer on one side is 20 μm-70 μm. In some embodiments, the thickness of the positive electrode film layer on one side is 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, or any range between any two of the foregoing values.

[0102] The thinning of the positive electrode film layer is conducive to reducing the diffusion path of lithium ions and improving the dynamic performance of battery cells; however, with the thinning of the positive electrode film layer, in order to make the battery have a high energy density, the compaction density of the pole piece is further increased, which makes the current collector more severely squeezed by large particles during slicing, and the probability of burrs is higher. At the same time, with the thinning of the positive electrode film layer and the positive electrode sheet, the burr control level of large-size specifications is tightened simultaneously, and the burrs are more likely to protrude from the edge of the positive electrode film layer, exacerbating the safety hazards of the burr problem.

[0103] In some embodiments, the thickness of the positive electrode current collector is 5 μm-20 μm. In some embodiments, the thickness of the positive electrode current collector is 7 μm-15 μm. In some embodiments, the thickness of the positive electrode current collector is 5 μm, 7 μm, 9 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, or any range between any two of the foregoing values.

[0104] The positive electrode current collector does not contribute to the capacity of the battery, and its thinning is conducive to making room for the positive electrode active material and improving the energy density of the battery cell. However, the thinning of the positive electrode current collector reduces its ability to withstand large particle extrusion during the slitting process, and the burr phenomenon is more serious. The thickness of the positive electrode current collector within the above range is conducive to improving the yield rate during the electrode cutting process while maintaining the high energy density of the battery cell, meeting the performance and efficiency requirements.

[0105] In some embodiments, the cold pressed density of the positive electrode plate is 3.1 g / cm 3 -3.8g / cm 3 In some embodiments, the cold pressed density of the positive electrode plate is 3.1 g / cm 3 、3.2g / cm 3 、3.3g / cm 3 、3.4g / cm 3 , 3.5g / cm3 、3.6g / cm 3 、3.7g / cm 3 、3.8g / cm 3 , or any range between any two of the aforementioned values.

[0106] When used herein, the cold pressed compaction density of the positive electrode sheet can be measured using instruments and methods known in the art. As an example, the following method can be used for testing: take a positive electrode sheet prepared after cold pressing, use an electronic balance to weigh the electrode sheet test sample with an area of ​​S, and record the weight as W, and then measure the thickness T of the electrode sheet (it can be measured using instruments that can measure the thickness of the electrode sheet in the art, including but not limited to instruments such as micrometers), and after the positive electrode sheet is cold pressed, the compaction density of the positive electrode sheet can be calculated by the formula W / (T×S).

[0107] In some embodiments, when the battery cell is fully charged, the compaction density of the positive electrode sheet is 3.4 g / cm 3 -3.7g / cm 3 In some embodiments, when the battery cell is fully charged, the compaction density of the positive electrode sheet is 3.4 g / cm 3 、3.45g / cm 3 , 3.5g / cm 3 、3.55g / cm 3 、3.6g / cm 3 、3.65g / cm 3 、3.7g / cm 3 , or any range between any two of the aforementioned values.

[0108] When used in this article, when the battery cell is fully discharged, the compaction density of the positive electrode plate can be measured using instruments and methods known in the art. As an example, the following method can be used for testing: place the battery cell at 25°C and let it stand for 2h. When the battery temperature is maintained at 25°C, discharge the battery at a constant current of 1 / 3C to 2.8V and then let it stand for 30min. Discharge it at a constant current of 0.04C to 2.8V, disassemble the fully discharged plate, clean the residual electrolyte with an organic solvent (the organic solvent can be a conventional solvent in the art that can clean the electrolyte, including but not limited to dimethyl carbonate, etc.), remove the residual electrolyte and dry the plate, and then use the aforementioned positive electrode plate compaction density measurement method to measure the compaction density of the positive electrode plate of the battery cell after full discharge.

[0109] The compaction density of the positive electrode sheet within the above range is beneficial to maintaining the high energy density of the battery cell while improving the yield rate in the electrode sheet cutting process, thereby meeting the performance and efficiency requirements.

[0110] In some embodiments, the bonding strength between the primer layer and the positive current collector is 5N / m-75N / m. In some embodiments, the bonding strength between the primer layer and the positive current collector is 5N / m-50N / m. In some embodiments, the bonding strength between the primer layer and the positive current collector is 5N / m, 10N / m, 15N / m, 20N / m, 25N / m, 30N / m, 35N / m, 40N / m, 45N / m, 50N / m, 55N / m, 60N / m, 65N / m, 70N / m, 75N / m, or any range between any two of the foregoing values.

[0111] The bonding strength between the primer layer and the positive electrode current collector within the above range is beneficial to improving the aluminum leakage of the pole piece and improving the cycle life of the battery.

[0112] In some embodiments, the thermal decomposition temperature of the positive electrode plate is 225° C.-255° C. In some embodiments, the thermal decomposition temperature of the positive electrode plate is 227° C.-250° C. In some embodiments, the thermal decomposition temperature of the positive electrode plate is 225° C., 230° C., 235° C., 240° C., 245° C., 250° C., 255° C., or any range between any two of the foregoing values.

[0113] In some embodiments, after the positive electrode sheet is cut at a cutting speed of 0.5 m / s to obtain 2000 sheets, the proportion of positive electrode sheets with burrs is 0%-0.05%. In some embodiments, the proportion of positive electrode sheets with burrs is 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or any range between any two of the foregoing values.

[0114] As used herein, a positive electrode sheet with burrs refers to a positive electrode sheet after slitting, and the size of the burrs on the sheet is calibrated. Burrs with a size greater than or equal to 40% of the thickness of the positive electrode sheet are included in the statistical range and calibrated as positive electrode sheets with burrs. The proportion of positive electrode sheets with burrs can be tested by methods known in the art. As an example, the following method can be used for testing: using the burr size measurement method as described above to observe a certain number of slit sheets through CCD, counting the frequency K1 of the sheets with burrs, and calculating the proportion of the sheets with burrs as K1 / total number of sheets × 100%.

[0115] As used herein, the term "burr size" refers to the absolute length of the burr (not limited to the vertical distance). The burr size can be tested using instruments and methods known in the art. For example, the following method can be used to test: use a CCD instrument to observe the burrs after cutting (such as Keyence 600), the test temperature is 25°C, the test electrode size is 80mm×60mm, the magnification is 300x, the light intake opening is 30%, and the burr size is calibrated, such as Figure 2 shown.

[0116] 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 material base and a metal layer formed on at least one surface of the polymer material base. 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, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0117] In some embodiments, the positive electrode film layer and the primer layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0118] In some embodiments, the positive electrode film layer and the undercoat layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the positive electrode plate can be prepared in the following manner: the components for preparing the primer layer, such as lithium-containing phosphate, conductive agent, binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a primer layer slurry; the components such as lithium-containing transition metal oxide, conductive agent, binder, etc. are dispersed in a solvent to form a positive electrode film layer slurry; the primer layer slurry is first coated on the positive electrode current collector, and after drying, the positive electrode film layer slurry is then coated on the surface of the primer layer, and after drying, cold pressing and other processes, the positive electrode plate can be obtained.

[0120] [Negative electrode] The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector.

[0121] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0122] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material 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, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0123] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0124] In some embodiments, the negative electrode film layer may further include a binder, which 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).

[0125] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0126] In some embodiments, the negative electrode film layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0127] In some embodiments, the negative electrode sheet can be prepared in the following manner: 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 collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0128] [Electrolytes] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0129] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0130] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0131] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0132] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0133] [Isolation film] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0134] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0135] [Battery Cell] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0136] In some embodiments, the volume energy density of the battery cell is 600Wh / L-720Wh / L. In some embodiments, the volume energy density of the battery cell is 600Wh / L, 610Wh / L, 620Wh / L, 630Wh / L, 640Wh / L, 650Wh / L, 660Wh / L, 670Wh / L, 680Wh / L, 690Wh / L, 700Wh / L, 710Wh / L, 720Wh / L, or any range between any two of the foregoing values.

[0137] When used in this article, the volume energy density of a battery cell can be measured by instruments and methods known in the art. As an example, the following method can be used for measurement: the weight M of all active materials loaded per unit area of ​​the positive electrode sheet in the battery cell is measured respectively, and the cell volume is V; each battery is charged at a rate of 0.33C at room temperature to a voltage equal to 4.25V, and then discharged at a rate of 0.33C to a voltage equal to 2.8V, and the discharge energy S0 is measured. Battery mass energy density = S0 / M; cell volume energy density = S0 / V.

[0138] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0139] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0140] The present application has no particular restrictions on the shape of the battery cell, which can be cylindrical, square or any other shape. For example, Figure 6 The battery cell 5 is a square structure as an example.

[0141] In some embodiments, reference Figure 7, the outer packaging may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0142] [Battery device] The present application also provides a battery device, which includes the battery cell provided in the present application. In some embodiments, the battery device is one or more of a battery module, a battery pack, and an energy storage device.

[0143] In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0144] Figure 8 4 is an example of a battery module. Figure 8 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0145] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0146] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0147] Fig. 9 and Fig.10 1 is a battery pack 1 as an example. Fig. 9 and Fig.10 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0148] [Electrical devices] In addition, an embodiment of the present application further provides an electric device, which includes at least one of the battery cells, battery modules, or battery packs provided in the embodiments of the present application. The battery cells, battery modules, or battery packs can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0149] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0150] Fig.11 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device's requirements for high power and high energy density of battery cells, a battery pack or a battery module can be used.

[0151] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery cell may be used as a power source.

[0152] Example Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0153] 1. Preparation method Example 1 1) Preparation of positive electrode Preparation of the bottom coating slurry: LiMn iron manganese phosphate with a Dv99 of 10 μm, a Dv50 of 0.6 μm, and a molar ratio of Mn element of 30% 0.3 Fe 0.7 PO4, conductive carbon, and binder PVDF are mixed in a mass ratio of 98:1:1, and a solvent N-methyl-2-pyrrolidone (NMP) is added, and the mixture is stirred under a vacuum stirrer until the system is uniform to obtain a primer slurry; Preparation of positive electrode film slurry: LiNi ternary active material with Dv99 of 28μm and Dv50 of 9μm 0.92 Co 0.04 Mn 0.04O2 polycrystalline particles, Dv99 of 12μm, Dv50 of 3μm ternary active material LiNi 0.92 Co 0.04 Mn 0.02 A mixture of O2 single crystal particles (the mass ratio of polycrystalline particles: single crystal particles is 7:3), conductive carbon, and binder PVDF are mixed in a mass ratio of 98:1:1, a solvent NMP is added, and the mixture is stirred under the action of a vacuum stirrer until the system is uniform, thereby obtaining a positive electrode film slurry; The primer slurry is evenly coated on both sides of the positive electrode current collector and then dried to form a primer layer, wherein the coating weight on one side is 3.65 mg / cm 2 ; The positive electrode film slurry is evenly coated on the surface of the base coating away from the positive electrode current collector, and the single-sided coating weight is 12.55 mg / cm 2 After drying at room temperature, the film was transferred to an oven for further drying, and then cold pressed to obtain a positive electrode sheet. After cold pressing, the thickness of the bottom coating on one side was 10 μm, the thickness of the positive electrode film on one side was 34 μm, and the compaction density of the positive electrode sheet was 3.65 g / cm 3 ; Pole sheet slitting (one out of two): the positive electrode sheet is slitting on the slitting machine, the slitting speed is 0.5m / s, the slitting knife is made of steel, and the negative pressure of the slitting machine is -10Kpa; Pole piece cutting: The slit pole pieces are wound and cut, with a winding speed of 0.6m / s, a core length of 3m, a cutting knife made of steel, and a negative pressure of -10Kpa in the winding machine.

[0154] 2) Preparation of negative electrode The negative electrode natural graphite, binder and conductive agent were fully mixed and ball-milled in a deionized water solvent system at a mass ratio of 90:5:5 to obtain a negative electrode slurry. The negative electrode slurry was mixed and ball-milled at a mass ratio of 155 mg / 1540.25 mm 2 The single-sided coating weight of the film was double-sided coated on the surface of the copper foil and vacuum dried overnight at a temperature of 110° C. to obtain a negative electrode sheet.

[0155] 3) Preparation of diaphragm A polyethylene film with a thickness of 7 μm was used as the separator.

[0156] 4) Preparation of electrolyte Lithium hexafluorophosphate (LiPF6) was dissolved in ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1 to form a uniform solution, thereby obtaining an electrolyte with a LiPF6 concentration of 1 mol / L.

[0157] 5) Battery assembly Place them in the order of "diaphragm-negative electrode sheet-diaphragm-positive electrode sheet", fix one end of the positive electrode sheet, negative electrode sheet and two separators to the discharge roller, and fix the other end to the winding shaft after stacking together. Use a motor to rotate the winding shaft, wind up the positive electrode sheet, negative electrode sheet and two separators, and obtain a wound bare cell. Place the bare cell in an outer package, inject the above-mentioned electrolyte and package it to obtain a battery cell.

[0158] Among them, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is 22μm, and the volume distribution curve of the particles shows a bimodal distribution, with the peak positions of 3μm and 9μm respectively, and the peak position difference is 6μm; The thickness of the bottom coating on one side is 10 μm; the thickness of the positive electrode film on one side is 34 μm; the thickness of the positive electrode sheet is 101 μm; The cold pressed density of the positive electrode is 3.65 g / cm 3 ; The thermal decomposition temperature of the positive electrode is 252℃.

[0159] Comparative Example 1 The preparation method of the battery cell of Comparative Example 1 is similar to that of the battery cell of Example 1, except that the positive electrode plate of Comparative Example 1 does not include a primer layer.

[0160] Comparative Examples 2-3 The preparation method of the battery monomers of Comparative Examples 2-3 is similar to that of the battery monomers in Example 1, except that the Dv90 of the positive electrode film layer particles in the positive electrode plate in Comparative Example 2 does not satisfy that the particle Dv90 is greater than or equal to 16 μm; the Dv99 of the particles in the bottom coating layer in the positive electrode plate in Comparative Example 3 does not satisfy that the particle Dv99 is less than or equal to 15 μm; the specific preparation parameters are shown in Table 1.

[0161] Embodiment 2-4 The preparation methods of the battery monomers of Examples 2-4 are similar to those of the battery monomers of Example 1, except that the particle size of the particles in the bottom coating layer is adjusted. The specific preparation parameters are shown in Table 1.

[0162] Example 5-11 The preparation methods of the battery cells of Examples 5-11 are similar to those of the battery cells of Example 1, except that the type of material in the primer layer is adjusted. The specific preparation parameters are shown in Table 1.

[0163] Example 12 The preparation method of the battery cell of Example 12 is similar to that of the battery cell of Example 1, except that the thickness of the single-sided bottom coating layer is adjusted. The specific preparation parameters are shown in Table 1.

[0164] Examples 13-14 The preparation method of the battery cells of Examples 13-14 is similar to that of the battery cells in Example 1, except that the particle sizes of the polycrystalline particles and the single crystal particles in the positive electrode film layer are adjusted. The specific preparation parameters are shown in Table 1.

[0165] Examples 15-16 The preparation method of the battery cells of Examples 15-16 is similar to that of the battery cells in Example 1, except that the mass ratio of polycrystalline particles to single crystal particles in the positive electrode film layer is adjusted. The specific preparation parameters are shown in Table 1.

[0166] Examples 17-18 The preparation methods of the battery cells of Examples 17-18 are similar to those of the battery cells of Example 1, except that the types of active materials in the positive electrode film layer are adjusted. The specific preparation parameters are shown in Table 1.

[0167] Table 1

[0168] 2. Performance Test 1. CP-SEM characterization method of positive electrode cross section The sample to be characterized was prepared as follows: first, the positive electrode sheet was cut into a sample to be tested with a size of 2 cm × 2 cm, and the sample to be tested was fixed on the sample stage by paraffin. Then, the sample stage was placed in the sample holder and locked, the power supply and vacuum of the argon ion cross-section polisher IB-19500CP were turned on, the argon gas flow rate was set to 0.15 MPa, the control voltage was set to 8 KV, and the polishing time was set to 2 hours, and the sample stage was adjusted to the swing mode to start polishing. After the polishing was completed, the sample to be characterized was obtained.

[0169] Microscopic morphology characterization: The samples were characterized using a scanning electron microscope ZEISS Sigma300. The sample test can refer to JY / T010-1996. In order to ensure the accuracy of the test results, multiple different areas can be randomly selected from the sample to be tested for scanning tests, and the cross-sectional morphology images can be taken at a fixed magnification of 5k times.

[0170] 2. Test method for particle size of positive electrode material The battery cells were disassembled, and the powders to be tested were scraped out from the positive electrode film layer and the bottom coating layer, respectively. The materials to be tested were poured into a wind dispersion tank filled with ethanol for ultrasonic dispersion for 5 minutes, and sodium dodecyl sulfate (SDS) was added as dispersant. Then, the materials were loaded into a laser particle size analyzer (Malvern 2000E) for testing to obtain the volume distribution particle size of the particles in the positive electrode film layer and the bottom coating layer.

[0171] 3. Characterization method of burrs on the cross section of positive electrode The super depth of field microscope (Keyence 600) was used to characterize the electrode after slitting. The test temperature was 25°C, the size of the test electrode was 80mm×60mm, the magnification was 300x, the light opening was 30%, and the burr characterization observation and size calibration were performed from the electrode section. The cross-sectional morphology of the positive electrode after slitting along the thickness direction in one embodiment of the present application and the comparative example is shown in FIG. Figure 2 , Figure 3 shown.

[0172] Statistics on the proportion of positive electrode pieces with burrs: 2000 cut pieces were observed by CCD, and the frequency of pieces with burrs, K1, was counted. The proportion of burrs was calculated to be K1 / 2000×100%.

[0173] 4. Positive electrode differential thermal analysis (DSC) test method The prepared positive electrode sheet or the positive electrode sheet disassembled from the battery cell is placed in a DSC crucible, the above electrolyte is added, the atmosphere is set to N2, the heating rate is 10℃ / min, the temperature range is 25℃-800℃, and the peak decomposition temperature of the positive electrode sheet is tested. The DCS differential thermal analysis curve comparison of the positive electrode sheet in the embodiment of the present application is shown in the figure below. Figure 4 shown.

[0174] 5. Test method for bonding strength of positive electrode sheet The prepared positive electrode sheet is cut into test specimens with a length of L: 100mm and a width of W: 20mm for use; one side of the double-sided tape is pasted to the surface of the steel plate, and the other side is adhered to the electrode to be tested, and compacted with a roller to make it completely fit with the electrode; one end of the current collector is reversely bent with a bending angle of 180°; a high-speed rail tensile testing machine is used for testing, one end of the steel plate is fixed to the lower fixture of the tensile testing machine, and the bent end of the current collector is fixed to the upper fixture, the angle of the current collector is adjusted to ensure that the upper and lower ends are in a vertical position, and then the sample is stretched at a speed of 50mm / min until the current collector is completely peeled off from the surface of the electrode, and the displacement and force in the process are recorded, and the strength when the force is balanced is recorded as the bonding force of the electrode as N1, and the bonding strength of the electrode can be calculated using the formula N1 / W.

[0175] 6. Battery cell cycle life test method The prepared battery cell was charged at a constant current of 0.33C to a voltage of 4.25V, and then discharged at a constant current of 0.33C to a voltage of 2.8V, and the reversible capacity was measured as C0. The charging and discharging were repeated until 800 cycles were completed, and the last reversible capacity was measured as C1. The capacity retention rate of the battery cell at this cycle number is (C1 / C0)×100%.

[0176] 7. Battery cell energy density test method The weight M of all active materials loaded per unit area of ​​the positive electrode sheet of the battery cell is measured respectively, and the cell volume is V; each battery is charged at a rate of 0.33C at room temperature to a voltage of 4.25V, and then discharged at a rate of 0.33C to a voltage of 2.8V, and the discharge energy S0 is measured. Battery mass energy density = S0 / M; cell volume energy density = S0 / V.

[0177] III. Analysis of test results of various embodiments and comparative examples Secondary batteries of various embodiments and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in the following table.

[0178] Table 2

[0179] From the comparison of the results of the embodiment and the comparative example, it can be seen that the volume distribution particle size Dv90 of the particles in the positive electrode film layer in the battery cell is greater than or equal to 16μm, and the volume distribution particle size Dv99 of the particles in the base coating layer is less than or equal to 15μm, which is beneficial to effectively reduce the probability of burrs generated during the electrode cutting process while maintaining the high energy density of the battery cell, so that the battery cell has both high energy density and low safety risk.

[0180] Table 3

[0181] From the comparison of Examples 1-4 in Table 3, it can be seen that when the volume particle size Dv50 of the particles in the base coating is 0.4μm-2.0μm, and can be further selected as 0.4μm-0.8μm, the battery cell can further improve the bonding strength between the positive electrode current collector and the positive electrode base coating while maintaining high energy density and low burr generation probability, which is beneficial to prevent powder loss during electrode cutting and further improve the safety performance of the battery cell.

[0182] Table 4

[0183] From the comparison of Examples 1 and 5-10 in Table 4, it can be seen that the lithium-containing transition metal phosphate in the primer layer includes Mn element, and when the molar proportion of Mn is 10-70% based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the battery monomer has a high energy density and a low probability of burr generation, and can further improve the cycle life of the battery monomer; further, when the molar proportion of Mn is 30%-50%, the battery monomer has a low probability of burr generation and has a higher energy density and a longer cycle life.

[0184] Table 5

[0185] From the comparison of Examples 1, 11, and Comparative Example 1 in Table 5 and Figure 4 It can be seen from the differential thermal analysis curve that when the base coating includes a lithium-containing transition metal phosphate, the battery cell has a high energy density, a low probability of burr generation and a high oxygen release temperature, which is beneficial to further improve the safety performance of the battery cell.

[0186] From the comparison of Examples 1 and 12 and Comparative Example 1 in Table 2, it can be seen that when the thickness of the single-sided bottom coating is 10 μm-20 μm, the battery cell has a lower probability of burr generation while having a high energy density, which is beneficial to further improve the comprehensive performance of the battery cell.

[0187] From the comparison of Examples 1 and 13-16 in Table 2, it can be seen that when the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16μm, the volume distribution particle size Dv99 of the polycrystalline particles is 18μm-30μm, Dv50 is 6μm-14μm, the volume distribution particle size Dv99 of the single crystal particles is 6μm-15μm, Dv50 is 1μm-6μm, and the mass ratio of polycrystalline particles to single crystal particles is 5:5-9:1, the energy density can be further improved while ensuring the safety performance of the battery cell.

[0188] From the comparison of Examples 1 and 17-18 in Table 2, it can be seen that when the positive electrode film layer includes a lithium-containing transition metal oxide and the nickel content is 80%-96%, the probability of generating burrs on the positive electrode plate can be reduced while further improving the energy density of the battery cell.

[0189] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell, comprising a positive electrode plate, characterized in that: The positive electrode sheet comprises a positive electrode current collector, a positive electrode film layer disposed on at least one side of the positive electrode current collector, and a primer layer disposed between the positive electrode current collector and at least one side of the positive electrode film layer, wherein the positive electrode film layer comprises a positive electrode active material, wherein the positive electrode active material comprises a lithium-containing transition metal oxide, The volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16 μm; The volume distribution particle size Dv99 of the particles in the primer layer is less than or equal to 15 μm.

2. The battery cell according to claim 1, characterized in that: The volume distribution particle size Dv90 of the particles in the positive electrode film layer is 16 μm-26 μm; and / or, The volume distribution particle size Dv99 of the particles in the base coating is 5 μm-15 μm.

3. The battery cell according to claim 1, characterized in that: The volume distribution particle size Dv50 of the particles in the base coating is 0.4 μm-2.0 μm.

4. The battery cell according to claim 3, characterized in that: The volume distribution particle size Dv50 of the particles in the base coating is 0.4 μm-1.5 μm.

5. The battery cell according to claim 3 or 4, characterized in that: The volume distribution particle size Dv50 of the particles in the base coating is 0.4 μm-0.8 μm.

6. The battery cell according to claim 1, characterized in that: The bottom coating layer includes a lithium-containing transition metal phosphate, wherein the general formula of the lithium-containing transition metal phosphate includes Li m Q q Fe x P y O j , 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, 0.6≤m≤1.15, 0≤x≤1, 0.95≤y≤1, 3.5≤j≤4, and 0≤q≤1.

7. The battery cell according to claim 6, characterized in that: The lithium-containing transition metal phosphate includes a Mn element. Based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar ratio of the Mn element in the lithium-containing transition metal phosphate is 10% to 70%.

8. The battery cell according to claim 7, characterized in that: The lithium-containing transition metal phosphate includes a Mn element. Based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar ratio of the Mn element in the lithium-containing transition metal phosphate is 30% to 50%.

9. The battery cell according to claim 1, characterized in that: The undercoat layer includes lithium manganese iron phosphate and one or more of its doped modified materials and coated modified materials. Based on the total molar number of Mn element and Fe element, the molar proportion of Mn element is 10% to 70%.

10. The battery cell according to claim 9, characterized in that: The undercoat layer includes lithium manganese iron phosphate and one or more of its doped modified materials and coated modified materials. Based on the total molar number of Mn element and Fe element, the molar proportion of Mn element is 30% to 50%.

11. The battery cell according to claim 1, characterized in that: The lithium-containing transition metal oxide includes nickel element. Based on the total molar number of transition metals in the lithium-containing transition metal oxide, the molar ratio of nickel element in the lithium-containing transition metal oxide is 80%-96%.

12. The battery cell according to claim 1, characterized in that: The volume distribution curve of the particles in the positive electrode film layer presents a bimodal distribution, and the peak position difference is greater than or equal to 3 μm and less than or equal to 8 μm.

13. The battery cell according to claim 12, characterized in that: In the volume distribution curve of particles in the positive electrode film layer, the double peaks are located at 1 μm-6 μm and 6 μm-14 μm respectively.

14. The battery cell according to claim 1, characterized in that: The particles in the positive electrode film layer include polycrystalline particles and single crystal particles.

15. The battery cell according to claim 14, characterized in that: The volume distribution particle size Dv99 of the polycrystalline particles is 18 μm-30 μm; and / or, The volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-14 μm.

16. The battery cell according to claim 15, characterized in that: The volume distribution particle size Dv99 of the polycrystalline particles is 20 μm-30 μm; and / or, The volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-12 μm.

17. The battery cell according to claim 14, characterized in that: The volume distribution particle size Dv99 of the single crystal particles is 6 μm-15 μm; and / or, The volume distribution particle size Dv50 of the single crystal particles is 1 μm-6 μm.

18. The battery cell according to claim 17, characterized in that: The volume distribution particle size Dv99 of the single crystal particles is 6 μm-13 μm; and / or, The volume distribution particle size Dv50 of the single crystal particles is 1 μm-4 μm.

19. The battery cell according to claim 14, characterized in that: The mass ratio of the polycrystalline particles to the single crystal particles is 5:5-9:

1.

20. The battery cell according to claim 18, characterized in that: The mass ratio of the polycrystalline particles to the single crystal particles is 6:4-8:

2.

21. The battery cell according to claim 1, characterized in that: The lithium-containing transition metal oxide includes Li a1 Ni x1 Co y1 M1 z1 M2 w1 O 2-b1 , wherein M1 includes one or more of Mn and Al, and M2 includes one or more of Zr, B, Mg, Ti, W, Mo, Nb, Ta, Sr, Sb, and K; 0.8≤a1≤1.2, 0≤x1≤1, 0≤y1≤1, 0≤z1≤1, 0≤w1≤0.1, and -0.1≤b1≤0.

1.

22. The battery cell according to claim 1, characterized in that: The thickness of the primer layer on one side is 5 μm to 20 μm.

23. The battery cell according to claim 22, characterized in that: The thickness of the primer layer on one side is 10-15 μm.

24. The battery cell according to claim 1, characterized in that The thickness of the positive electrode film layer on one side is 20 μm-70 μm.

25. The battery cell according to claim 1, characterized in that The thickness of the positive electrode current collector is 5 μm-20 μm.

26. The battery cell according to claim 25, characterized in that: The thickness of the positive electrode current collector is 7 μm-15 μm.

27. The battery cell according to claim 1, characterized in that: When the battery cell is fully charged, the compaction density of the positive electrode sheet is 3.4 g / cm 3 -3.7g / cm 3 .

28. The battery cell according to claim 1, characterized in that: The bonding strength between the primer layer and the positive electrode current collector is 5N / m-75N / m.

29. The battery cell according to claim 28, characterized in that: The bonding strength between the primer layer and the positive electrode current collector is 5 N / m-50 N / m.

30. The battery cell according to claim 1, characterized in that The thermal decomposition temperature of the positive electrode plate is 225°C-255°C.

31. The battery cell according to claim 30, characterized in that: The thermal decomposition temperature of the positive electrode plate is 227°C-250°C.

32. The battery cell according to claim 1, characterized in that After the positive electrode sheets are cut at a cutting speed of 0.5 m / s to obtain at least 2000 sheets, the proportion of positive electrode sheets with burrs is 0%-0.05%.

33. The battery cell according to claim 1, characterized in that: The volume energy density of the battery cell is 600Wh / L-720Wh / L.

34. A battery device, characterized in that: The battery device comprises the battery cell according to any one of claims 1 to 33, and the battery device is one or more of a battery module, a battery pack, and an energy storage device.

35. An electrical device, characterized in that: The electrical device comprises the battery cell according to any one of claims 1 to 33 or the battery device according to claim 34.

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