Battery cells, battery devices and power-consuming devices

Abstract

The present application provides a battery cell, a battery device, and an electrical device, belonging to the field of battery technology. The battery cell provided in the present application includes a positive electrode plate, the positive electrode plate including a positive electrode current collector, a positive electrode film layer disposed on at least one side of the positive electrode current collector, and an undercoat layer disposed between the positive electrode current collector and the positive electrode film layer on the 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; the volume distribution particle size Dv99 of the particles in the undercoat layer is less than or equal to 15μm. The battery cell provided in the present application 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 systems such as hydropower, thermal, wind, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. However, the market's pursuit of superior electrical performance in battery cells has increased the difficulty of processing them, leading to a decrease in yield. This has resulted in battery safety and service life failing to meet expectations, limiting further applications. Striking a balance between these two issues has become a pressing challenge 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, which includes a positive electrode plate, the positive electrode plate including a positive electrode collector, a positive electrode film layer arranged on at least one side of the positive electrode collector, and a primer layer arranged between the positive electrode collector and the positive electrode film layer on at least one side, the positive electrode film layer including a positive electrode active material, the positive electrode active material including 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 primer layer is less than or equal to 15μm, and can be optionally 5μm-15μm.

[0005] The battery cell positive electrode film layer 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 provided between the positive electrode film layer and the positive electrode current collector. This buffers the squeezing of the current collector by large particles in the positive electrode film layer during slicing, reduces the probability of large-sized burrs being generated during the electrode cutting process, and improves the yield rate during the electrode cutting process while maintaining the high energy density of the battery cell, thereby meeting performance and efficiency requirements.

[0006] In any embodiment, the volume distribution particle size Dv50 of the particles in the primer 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 improves the adhesion between the positive electrode current collector and the base coating layer, effectively preventing powder loss, aluminum leakage, etc. when the electrode is 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 polyanionic 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 alleviate collector extrusion, improve burr phenomena, and improve the safety performance and service life of battery cells.

[0010] In any embodiment, 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 proportion of the Mn element in the lithium-containing transition metal phosphate is 10% to 70%, and can be optionally 30% to 50%.

[0011] Research has shown that conventional lithium iron phosphate materials have a voltage platform that is too low (~3.2V) compared to lithium-containing transition metal oxides. This lowers the voltage platform of the battery cell during operation, making it difficult to fully utilize the specific capacity of lithium iron phosphate. Introducing the element manganese into lithium iron phosphate can effectively increase the voltage platform of lithium iron phosphate (~3.7V), matching it with the voltage window of the lithium-containing transition metal oxide in the positive electrode film. This helps maximize the specific capacity of the material and allows the undercoat layer to reduce the probability of burrs while also minimizing the negative impact on battery energy density.

[0012] In any embodiment, 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%~70%, and can be optionally 30%~50%.

[0013] Introducing the Mn element into the lithium iron phosphate active material of the bottom coating can increase the voltage platform of the active material and adapt to the voltage platform window of the lithium-containing transition metal oxide, thereby improving the energy density of the battery cell; however, the Mn ion has a large ionic radius, is prone to crystal structure distortion, and has 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, and the molar ratio of nickel in the lithium-containing transition metal oxide is 80%-96% based on the total moles of transition metals in the lithium-containing transition metal oxide.

[0015] Lithium-containing transition metal oxides with a molar percentage of 80%-96% nickel have high gram capacity, which is beneficial for further improving the energy density of battery cells. However, this also increases the hardness of the particles in the positive electrode film, exacerbating the compression of large particles on the current collector, making it easy to generate large burrs during the slitting of the positive electrode sheets. The technical solutions in the embodiments of this application are particularly suitable for such positive electrode sheets, further improving the high energy density of the battery while increasing the yield rate during the sheet cutting process, meeting 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 the particles in the positive electrode film layer, the bimodal 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, 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, optionally 20 μm-30 μm; and / or the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm-14 μm, optionally 6 μm-12 μm.

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

[0026] When the positive electrode film layer includes the above-mentioned 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 optionally 10-15 μm.

[0028] When the thickness of the single-sided primer coating 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 electrode during cutting, and further improve the safety performance of the battery cell; at the same time, it can reduce the deterioration of the electrode compaction and battery capacity loss caused by the addition of the primer 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] Reducing the thickness of the positive electrode film helps reduce the diffusion path of lithium ions and improve the dynamic performance of battery cells. However, as the thickness of the positive electrode film decreases, the compaction density of the electrode sheet is further increased to achieve high energy density. This increases the pressure on the current collector from large particles during slicing, increasing the probability of burrs. Furthermore, as the thickness of the positive electrode film and the electrode sheet decreases, the control of burrs on large-sized products becomes increasingly stringent, making burrs more likely to protrude from the edge of the positive electrode film, exacerbating the safety risks posed by burrs.

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

[0032] The positive electrode current collector does not contribute to battery capacity, so reducing its thickness helps free up space for the positive electrode active material, thereby increasing the energy density of the battery cell. However, this thinning reduces its ability to withstand large particle extrusion during the slitting process, exacerbating burring. Maintaining the positive electrode current collector thickness within the above range helps improve the yield rate during the electrode sheet cutting process while maintaining high battery cell energy density, thereby meeting 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 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 optionally 5 N / m-50 N / m.

[0036] The bonding strength between the primer layer and the positive electrode current collector being within the above range is beneficial to improving the phenomenon of aluminum leakage from the electrode 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 components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0044] Figure 1 This is a cross-sectional polished electron microscope image of the positive electrode sheet in one embodiment of the present application;

[0045] 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;

[0046] Figure 3 This is a cross-sectional morphology diagram of a positive electrode sheet cut along the thickness direction in one embodiment of the present application;

[0047] Figure 4 This is a comparison diagram of differential thermal analysis curves of the positive electrode sheet in one embodiment of the present application;

[0048] Figure 5 This 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;

[0049] Figure 6 is a schematic diagram of a battery cell according to one embodiment of the present application;

[0050] Figure 7 yes Figure 6 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0051] Figure 8 is a schematic diagram of a battery module according to one embodiment of the present application;

[0052] Figure 9 is a schematic diagram of a battery pack according to one embodiment of the present application;

[0053] Figure 10 yes Figure 9 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0054] Figure 11 FIG. 1 is a schematic diagram of an electrical device using a secondary battery according to an embodiment of the present application as a power source.

[0055] Description of reference numerals:

[0056] 11 positive electrode sheet; 111 positive electrode current collector; 112 base coating; 113 positive electrode film layer

[0057] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0058] Below, the embodiments of the battery cells, battery devices, and electrical devices of the present application are described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0059] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0061] 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.

[0062] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating 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), indicating 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.

[0063] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0064] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0065] As the market demands for the endurance of electrical devices increase, increasing the volumetric energy density of battery cells has become a common pursuit in the industry. Increasing the volumetric energy density of battery cells often requires increasing the compaction density of the pole pieces to increase the load of active material per unit volume. However, researchers have found that pole pieces with high compaction density are prone to large burrs during the cutting process. Pole pieces with large burrs can easily penetrate the diaphragm after assembly of the electrode assembly, causing abnormal self-discharge of the battery cell, and even leading to 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.

[0066] Based on the above problems, the embodiment of the first aspect of the present application provides a battery cell. Figure 1As 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.

[0067] In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is greater than or equal to 16 μm. In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer is 16 μm-26 μm. In some embodiments, the volume distribution particle size Dv90 of the particles in the positive electrode film layer can be selected as 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 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.

[0068] 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 between 5 μm and 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.

[0069] As 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.

[0070] 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 field. 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).

[0071] 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 measured by any method known in the art. As an example, powder can be scraped from the positive electrode film layer or the undercoat layer and measured using the method described above.

[0072] Lithium-containing transition metal oxides are an important class of positive electrode materials for lithium-ion batteries. They are 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.

[0073] 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 gradation 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 be squeezed and deformed instead of cut off, resulting in a large number of large-sized burrs, such as Figure 2 As shown, this affects the safety performance of the battery. 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, while improving the battery energy density, also make the burr problem more significant.

[0074] 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 cutting process, such as Figure 3 As shown, while maintaining the high energy density of the battery cell, the yield rate in the electrode cutting process is improved to meet the performance and efficiency requirements.

[0075] In some embodiments, the volume distribution particle size Dv50 of the particles in the primer layer is 0.4 μm to 2.0 μm. In some embodiments, the volume distribution particle size Dv50 of the particles in the primer layer is 0.4 μm to 1.5 μm.

[0076] 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.

[0077] 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 improves the adhesion between the positive electrode current collector and the base coating layer, effectively preventing powder loss, aluminum leakage, etc. when the electrode is cut, thereby improving the safety performance of the battery.

[0078] In some embodiments, the undercoat layer comprises a lithium-containing transition metal phosphate having a general formula comprising 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.

[0079] 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.

[0080] Lithium-containing transition metal phosphates are generally polyanionic 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 alleviate collector extrusion, improve burr phenomena, and improve the safety performance and service life of battery cells.

[0081] In some embodiments, the lithium-containing transition metal phosphate includes Mn element.

[0082] Research has shown that conventional lithium iron phosphate materials have a voltage platform that is too low (~3.2V) compared to lithium-containing transition metal oxides. This lowers the voltage platform of the battery cell during operation, making it difficult to fully utilize the specific capacity of lithium iron phosphate. Introducing the element manganese into lithium iron phosphate can effectively increase the voltage platform of lithium iron phosphate (~3.7V), matching it with the voltage window of the lithium-containing transition metal oxide in the positive electrode film. This helps maximize the specific capacity of the material and allows the undercoat layer to reduce the probability of burrs while also minimizing the negative impact on battery energy density.

[0083] In some embodiments, based on the total molar number of transition metal elements in the lithium-containing transition metal phosphate, the molar proportion of the Mn element in the lithium-containing transition metal phosphate is 10% to 70%, and can be optionally 30% to 50%.

[0084] 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.

[0085] Introducing the Mn element into the lithium iron phosphate active material of the bottom coating can increase the voltage platform of the active material and adapt to the voltage platform window of the lithium-containing transition metal oxide, thereby improving the energy density of the battery cell; however, the Mn ion has a large ionic radius, is prone to crystal structure distortion, and has 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.

[0086] In some embodiments, the undercoat layer includes lithium manganese iron phosphate and one or more of its doping and coating modification materials, and the molar ratio of the Mn element, based on the total molar ratio of the Mn element and the Fe element, is 10% to 70%, and optionally 30% to 50%. In some embodiments, the molar ratio of the Mn element, based on the total molar ratio of the Mn element and the Fe element, is 10%, 20%, 30%, 40%, 50%, 60%, 70%, or any range between any two of the foregoing values.

[0087] In some embodiments, the lithium-containing transition metal oxide includes nickel, and the molar ratio of nickel in the lithium-containing transition metal oxide is 80%-96% based on the total moles of transition metals in the lithium-containing transition metal oxide.

[0088] 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 as 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, or any range between any two of the foregoing numerical ranges.

[0089] As used herein, the molar fraction of nickel in the lithium-containing transition metal oxide can be determined by instruments and methods known in the art based on the total molar fraction of transition metals in the lithium-containing transition metal oxide. As an example, the following method can be used for measurement: 0.5 g of the material to be tested is immersed in 100 mL of aqua regia solution for digestion at a digestion temperature of 50° C., and then the completely dissolved solution is subjected to inductively coupled plasma (ICP) testing to detect the content of transition metals (such as Ni, Co, Mn ions) in the solution. The molar fraction of nickel in the lithium-containing transition metal oxide is calculated by dividing the molar fraction of nickel by the total molar fraction of transition metals based on the total molar fraction of transition metals in the lithium-containing transition metal oxide.

[0090] Lithium-containing transition metal oxides with a molar percentage of 80%-96% nickel have high gram capacity, which is beneficial for further improving the energy density of battery cells. However, this also increases the hardness of the particles in the positive electrode film, exacerbating the compression of large particles on the current collector, making it easy to generate large burrs during the slitting of the positive electrode sheets. The technical solutions in the embodiments of this application are particularly suitable for such positive electrode sheets, further improving the high energy density of the battery while increasing the yield rate during the sheet cutting process, meeting performance and efficiency requirements.

[0091] 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.

[0092] 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.

[0093] In some embodiments, in the volume distribution curve of particles in the positive electrode film layer, the bimodal peaks are located at 1 μm-6 μm and 6 μm-14 μm, respectively.

[0094] In some embodiments, in the volume distribution curve of the particles in the positive electrode film layer, one of the peak positions in the bimodal peak position 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 position in the bimodal peak position 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.

[0095] The volume distribution curve of the particles in the positive electrode film layer can refer to GB / T19077-2016 and be tested 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 5 The volume distribution curve of the particles in the positive electrode film layer shows a bimodal distribution, indicating that the positive electrode film layer contains 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.

[0096] In some embodiments, 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.

[0097] 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 orientations. 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.

[0098] 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 it is impossible to define smaller particles within it. It is understood that the single crystal particles described herein do not necessarily mean that there are no grain boundaries within the single crystal, and that it is a continuous and consistent periodic arrangement of atoms, molecules or ions in three-dimensional space. Instead, it refers to the inability to define smaller particles within the single crystal through grain boundaries at a certain observation scale. The single crystal particles referred to herein are 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.

[0099] In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is between 18 μm and 30 μm. In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is between 20 μm and 30 μm. In some embodiments, the volume distribution particle size Dv99 of the polycrystalline particles is between 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.

[0100] In some embodiments, the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm to 14 μm. In some embodiments, the volume distribution particle size Dv50 of the polycrystalline particles is 6 μm to 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.

[0101] In some embodiments, the volume distribution particle size Dv99 of the single crystal particles is 6 μm to 15 μm. In some embodiments, the volume distribution particle size Dv99 of the single crystal particles is 6 μm to 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.

[0102] In some embodiments, the volume distribution particle size Dv50 of the single crystal particles is 1 μm to 6 μm. In some embodiments, the volume distribution particle size Dv50 of the single crystal particles is 1 μm to 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.

[0103] 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, thereby increasing the energy density of the battery.

[0104] 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.

[0105] 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 CP-SEM testing. 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.

[0106] Controlling the mass ratio of polycrystalline particles to 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.

[0107] In some embodiments, 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.

[0108] 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.

[0109] When the positive electrode film layer includes the above-mentioned 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.

[0110] In some embodiments, the thickness of the primer layer on one side is 5 μm-15 μm, optionally 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.

[0111] The thickness of the primer layer on one side can be measured by observing and measuring the cross section of the positive electrode sheet using a scanning electron microscope.

[0112] When the thickness of the single-sided primer coating 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 electrode during cutting, and further improve the safety performance of the battery cell; at the same time, it can reduce the deterioration of the electrode compaction and battery capacity loss caused by the addition of the primer coating, so that the battery cell still has a high energy density.

[0113] 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.

[0114] Reducing the thickness of the positive electrode film helps reduce the diffusion path of lithium ions and improve the dynamic performance of battery cells. However, as the thickness of the positive electrode film decreases, the compaction density of the electrode sheet is further increased to achieve high energy density. This increases the pressure on the current collector from large particles during slicing, increasing the probability of burrs. Furthermore, as the thickness of the positive electrode film and the electrode sheet decreases, the control of burrs on large-sized products becomes increasingly stringent, making burrs more likely to protrude from the edge of the positive electrode film, exacerbating the safety risks posed by burrs.

[0115] In some embodiments, the thickness of the positive electrode current collector is 5 μm to 20 μm. In some embodiments, the thickness of the positive electrode current collector is 7 μm to 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.

[0116] The positive electrode current collector does not contribute to battery capacity, so reducing its thickness helps free up space for the positive electrode active material, thereby increasing the energy density of the battery cell. However, this thinning reduces its ability to withstand large particle extrusion during the slitting process, exacerbating burring. Maintaining the positive electrode current collector thickness within the above range helps improve the yield rate during the electrode sheet cutting process while maintaining high battery cell energy density, thereby meeting performance and efficiency requirements.

[0117] In some embodiments, the cold pressed density of the positive electrode is 3.1 g / cm 3 -3.8g / cm 3 In some embodiments, the cold pressed density of the positive electrode is 3.1 g / cm 3 、3.2g / cm 3 , 3.3g / cm 3 、3.4g / cm 3 , 3.5g / cm 3 、3.6g / cm 3 、3.7g / cm 3 、3.8g / cm 3 , or any range between any two of the above values.

[0118] As used herein, the cold-pressed compaction density of the positive electrode sheet can be measured using instruments and methods known in the art. For example, the following method can be used for testing: Take a positive electrode sheet prepared after cold pressing, use an electronic balance to weigh a sample of the sheet with an area of ​​S, and record the weight as W. Then, measure the thickness T of the sheet (which can be measured using a conventional instrument in the art capable of measuring the thickness of a sheet, including but not limited to a micrometer). After the positive electrode sheet is cold pressed, the compaction density of the positive electrode sheet can be calculated using the formula W / (T×S).

[0119] 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 above values.

[0120] As used herein, when the battery cell is fully discharged, the compacted 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 2 hours. After the battery temperature is maintained at 25°C, discharge the battery at a constant current of 1 / 3C to 2.8V, let it stand for 30 minutes, and then 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 then dry the plate. Then, use the aforementioned positive electrode plate compacted density measurement method to measure the compacted density of the positive electrode plate of the battery cell after full discharge.

[0121] 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 performance and efficiency requirements.

[0122] In some embodiments, the bonding strength between the primer layer and the positive electrode current collector is 5 N / m-75 N / m. In some embodiments, the bonding strength between the primer layer and the positive electrode current collector is 5 N / m-50 N / m. In some embodiments, the bonding strength between the primer layer and the positive electrode current collector is 5 N / m, 10 N / m, 15 N / m, 20 N / m, 25 N / m, 30 N / m, 35 N / m, 40 N / m, 45 N / m, 50 N / m, 55 N / m, 60 N / m, 65 N / m, 70 N / m, 75 N / m, or any range between any two of the foregoing values.

[0123] The bonding strength between the primer layer and the positive electrode current collector being within the above range is beneficial to improving the phenomenon of aluminum leakage from the electrode piece and improving the cycle life of the battery.

[0124] In some embodiments, the thermal decomposition temperature of the positive electrode plate is 225° C. to 255° C. In some embodiments, the thermal decomposition temperature of the positive electrode plate is 227° C. to 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.

[0125] In some embodiments, after the positive electrode sheets are 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.

[0126] As used herein, a positive electrode sheet with burrs refers to a sheet of positive electrode sheet that has been slit, 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 are calibrated as positive electrode sheets with burrs. The proportion of positive electrode sheets with burrs can be tested using methods known in the art. As an example, the following method can be used to test: a certain number of slit electrode sheets are observed through a CCD using the burr size measurement method described above, and the frequency K1 of electrode sheets with burrs is counted. The proportion of electrode sheets with burrs is calculated as K1 / total number of electrode sheets × 100%.

[0127] 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: observe the burrs after slicing using a CCD instrument (such as Keyence 600), the test temperature is 25°C, the test electrode size is 80mm×60mm, the magnification is 300x, the light input opening is 30%, and the burr size is calibrated, such as Figure 2 shown.

[0128] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0129] In some embodiments, the positive electrode film layer and the undercoat layer may further optionally include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0130] In some embodiments, the positive electrode film layer and the undercoat layer may further optionally include a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the above-mentioned 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 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. After drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0132] [Negative electrode]

[0133] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector.

[0134] 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 either or both of the two opposite surfaces of the negative electrode current collector.

[0135] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0136] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well 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 oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, 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.

[0137] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0138] 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.

[0139] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0140] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0141] [Electrolytes]

[0142] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0143] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0144] In some embodiments, the electrolyte salt may 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.

[0145] 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, methylpropyl carbonate, ethylpropyl 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, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0146] In some embodiments, the electrolyte may further include additives. For example, the additives may include 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, and additives that improve battery high or low temperature performance.

[0147] [Isolation film]

[0148] 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 and mechanical stability can be selected.

[0149] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0150] [Battery Cell]

[0151] 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.

[0152] In some embodiments, the volumetric energy density of the battery cell is 600Wh / L-720Wh / L. In some embodiments, the volumetric 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.

[0153] As used herein, the volumetric energy density of a battery cell can be measured using instruments and methods known in the art. For example, the following method can be used: The weight M of all active materials per unit area of ​​the positive electrode sheet in each battery cell is measured, with the cell volume V. Each battery is charged at room temperature at a 0.33C rate to a voltage of 4.25V, and then discharged at a 0.33C rate to a voltage of 2.8V, to obtain the discharge energy S0. Battery mass energy density = S0 / M; cell volume energy density = S0 / V.

[0154] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0155] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0156] 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.

[0157] In some embodiments, reference Figure 7 , the outer packaging may include a shell 51 and a cover plate 53. 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.

[0158] [Battery device]

[0159] The present invention also provides a battery device, which includes the battery cell provided in the present invention. In some embodiments, the battery device is one or more of a battery module, a battery pack, and an energy storage device.

[0160] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain one or more battery cells. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0161] 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. The plurality of battery cells 5 may further be fixed by fasteners.

[0162] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0163] 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 based on the application and capacity of the battery pack.

[0164] Figure 9 and Figure 10 The battery pack 1 is used as an example. Figure 9 and Figure 10The battery pack 1 may include a battery box and multiple 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 an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0165] [Electrical devices]

[0166] In addition, an embodiment of the present application further provides an electrical device, the electrical device comprising 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 electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, 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, satellites, energy storage systems, etc.

[0167] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0168] Figure 11 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery cells in this device, a battery pack or battery module can be used.

[0169] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0170] Example

[0171] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0172] 1. Preparation method

[0173] Example 1

[0174] 1) Preparation of positive electrode sheet

[0175] Preparation of the bottom coating slurry: lithium manganese iron phosphate LiMn with a Dv99 of 10μm, a Dv50 of 0.6μm, and a Mn element molar ratio of 30%0.3 Fe 0.7 PO4, conductive carbon, and binder PVDF were mixed in a mass ratio of 98:1:1, and solvent N-methyl-2-pyrrolidone (NMP) was added. The mixture was stirred in a vacuum mixer until the system became uniform to obtain a primer slurry.

[0176] Preparation of positive electrode film slurry: LiNi ternary active material with Dv99 of 28μm and Dv50 of 9μm 0.92 Co 0.04 Mn 0.04 O2 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 to single crystal particles is 7:3), conductive carbon, and binder PVDF are mixed in a mass ratio of 98:1:1, and solvent NMP is added. The mixture is stirred in a vacuum mixer until the system becomes uniform to obtain a positive electrode film slurry.

[0177] 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 ;

[0178] Electrode slitting (one out of two): The positive electrode is cut on the slitting machine with a slitting speed of 0.5m / s. The slitting knife is made of steel and the negative pressure of the slitting machine is -10Kpa.

[0179] 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 steel blade as the cutting blade, and a negative pressure of -10Kpa inside the winding machine.

[0180] 2) Preparation of negative electrode sheet

[0181] 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 copper foil 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.

[0182] 3) Preparation of diaphragm

[0183] A polyethylene film with a thickness of 7 μm was used as the separator.

[0184] 4) Preparation of electrolyte

[0185] 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.

[0186] 5) Battery assembly

[0187] The cells are arranged in the order of "diaphragm - negative electrode sheet - separator - positive electrode sheet". One end of the positive electrode sheet, negative electrode sheet, and two separators are fixed to the discharge roller, and the other end is fixed to the winding shaft after being stacked together. A motor rotates the winding shaft, winding the positive electrode sheet, negative electrode sheet, and two separators to form a wound bare cell. The bare cell is placed in an outer packaging, injected with the above-mentioned electrolyte, and encapsulated to form a battery cell.

[0188] 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;

[0189] The thickness of the primer layer on one side is 10 μm; the thickness of the positive electrode film layer on one side is 34 μm; the thickness of the positive electrode sheet is 101 μm;

[0190] The cold pressed density of the positive electrode is 3.65 g / cm 3 ;The thermal decomposition temperature of the positive electrode is 252℃.

[0191] Comparative Example 1

[0192] 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 sheet in Comparative Example 1 does not include a primer layer.

[0193] Comparative Examples 2-3

[0194] The preparation method of the battery cell of Comparative Example 2-3 is similar to that of the battery cell 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 meet the requirement of being 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 meet the requirement of being less than or equal to 15 μm; the specific preparation parameters are shown in Table 1.

[0195] Examples 2-4

[0196] The preparation methods of the battery cells of Examples 2-4 are similar to those of the battery cells of Example 1, except that the particle size of the particles in the primer layer is adjusted. The specific preparation parameters are shown in Table 1.

[0197] Examples 5-11

[0198] The preparation methods of the battery cells of Examples 5-11 are similar to those of the battery cell of Example 1, except that the type of material in the primer layer is adjusted. The specific preparation parameters are shown in Table 1.

[0199] Example 12

[0200] 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 primer layer is adjusted. The specific preparation parameters are shown in Table 1.

[0201] Examples 13-14

[0202] 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.

[0203] Examples 15-16

[0204] 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.

[0205] Examples 17-18

[0206] The preparation method of the battery cells of Examples 17-18 is similar to that of the battery cells in Example 1, except that the type of active material in the positive electrode film layer is adjusted. The specific preparation parameters are shown in Table 1.

[0207] Table 1

[0208]

[0209] 2. Performance Testing

[0210] 1. CP-SEM characterization method of the cross section of the positive electrode

[0211] The sample to be characterized was prepared as follows: First, the positive electrode sheet was cut into 2 cm × 2 cm specimens and secured to the sample stage with paraffin wax. The sample stage was then placed in the sample holder and locked securely. The argon ion cross-section polisher IB-19500CP was powered on and vacuumed. The argon flow rate was set to 0.15 MPa, the control voltage to 8 kV, and the polishing time to 2 hours. The sample stage was then set to rocking mode and polishing began. After polishing, the sample to be characterized was obtained.

[0212] Micromorphology Characterization: Samples were characterized using a ZEISS Sigma300 scanning electron microscope. Sample testing can refer to JY / T010-1996. To ensure the accuracy of the test results, multiple randomly selected areas of the sample were scanned and cross-sectional morphology images were captured at a fixed magnification of 5kx.

[0213] 2. Test method for particle size of positive electrode material

[0214] The battery cells were disassembled, and the powder to be tested was 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 a dispersant. The materials were then 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.

[0215] 3. Characterization method of burrs on the cross section of positive electrode

[0216] The super depth of field microscope (Keyence 600) was used to characterize the electrode after slitting. The test temperature was 25 ° C, the test electrode size was 80 mm × 60 mm, the magnification was 300x, the light opening was 30%, and the burr characterization and size calibration were performed on 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 as follows: Figure 2 、 Figure 3 shown.

[0217] Statistics on the proportion of positive electrode pieces with burrs: 2000 cut pieces were observed by CCD, and the frequency K1 of the pieces with burrs was counted. The burr proportion was calculated to be K1 / 2000×100%.

[0218] 4. Positive electrode differential thermal analysis (DSC) test method

[0219] Place the prepared positive electrode sheet or the positive electrode sheet disassembled from the battery cell in a DSC crucible, add the above electrolyte, set the atmosphere to N2, increase the temperature at a rate of 10°C / min, and test the peak decomposition temperature of the positive electrode sheet in the temperature range of 25°C-800°C. Figure 4 shown.

[0220] 5. Test method for bonding strength of positive electrode sheet

[0221] The prepared positive electrode sheet was cut into test specimens with a length of L: 100mm and a width of W: 20mm for later use; one side of the double-sided tape was pasted on the surface of the steel plate, and the other side was 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 was bent in the opposite direction with a bending angle of 180°; a high-speed rail tensile testing machine was used for testing, one end of the steel plate was fixed to the lower fixture of the tensile testing machine, and the bent end of the current collector was fixed to the upper fixture, the angle of the current collector was adjusted to ensure that the upper and lower ends were in a vertical position, and then the sample was stretched at a speed of 50mm / min until the current collector was completely peeled off from the surface of the electrode, the displacement and force during the process were recorded, and the strength when the force was balanced was 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.

[0222] 6. Battery cell cycle life test method

[0223] The prepared battery cell was charged at a constant current rate of 0.33C to a voltage of 4.25V, and then discharged at a constant current rate of 0.33C to a voltage of 2.8V. The reversible capacity was measured as C0. The charge and discharge cycles were repeated until 800 cycles were completed. The last reversible capacity was measured as C1. The capacity retention rate of the battery cell at this cycle number is (C1 / C0)×100%.

[0224] 7. Battery cell energy density test method

[0225] Measure the weight M of all active materials per unit area of ​​the positive electrode sheet of each battery cell, and the cell volume V. Measure the discharge energy, S0, when each battery is charged at room temperature at a 0.33C rate to a voltage of 4.25V, and then discharged at a 0.33C rate to a voltage of 2.8V. Battery mass energy density = S0 / M; cell volume energy density = S0 / V.

[0226] 3. Analysis of test results of various embodiments and comparative examples

[0227] Secondary batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in the table below.

[0228] Table 2

[0229]

[0230] 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 16 μm, and the volume distribution particle size Dv99 of the particles in the primer layer is less than or equal to 15 μm, 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.

[0231] Table 3

[0232]

[0233] 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 primer layer is 0.4μm-2.0μm, and can further be 0.4μm-0.8μm, the battery cell can further improve the bonding strength between the positive electrode current collector and the positive electrode primer layer 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.

[0234] Table 4

[0235]

[0236] From the comparison of Examples 1 and 5-10 in Table 4, it can be seen that when the lithium-containing transition metal phosphate in the primer layer includes the Mn element and 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, while being able to 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 while having a higher energy density and a longer cycle life.

[0237] Table 5

[0238]

[0239] From the comparison of Examples 1, 11 and Comparative Example 1 in Table 5 and Figure 4 The differential thermal analysis curve shows that when the base coating includes 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 conducive to further improving the safety performance of the battery cell.

[0240] 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 primer layer is 10 μm-20 μm, the battery cell has a lower probability of burr generation while having a high energy density, which is conducive to further improving the overall performance of the battery cell.

[0241] 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 16 μm, the volume distribution particle size Dv99 of the polycrystalline particles is 18 μm-30 μm, Dv50 is 6 μm-14 μm, the volume distribution particle size Dv99 of the single crystal particles is 6 μm-15 μm, Dv50 is 1 μm-6 μm, 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.

[0242] 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 a nickel content of 80%-96%, the probability of generating burrs on the positive electrode sheet can be reduced while further improving the energy density of the battery cell.

[0243] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A battery cell comprising a positive electrode plate, characterized in that: The positive electrode sheet includes a positive electrode current collector, a positive electrode film layer disposed on at least one side of the positive electrode current collector, and an undercoat layer disposed between the positive electrode current collector and the positive electrode film layer on at least one side. The positive electrode film layer includes a positive electrode active material, which is a lithium-containing transition metal oxide. The undercoat layer includes a lithium-containing transition metal phosphate. 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, wherein: 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 primer layer is 5 μm-15 μm.

3. The battery cell according to claim 1, wherein: The volume distribution particle size Dv50 of the particles in the primer layer 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 primer layer 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 primer layer is 0.4 μm-0.8 μm.

6. The battery cell according to claim 1, characterized in that 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 proportion 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 proportion 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 doping modification materials and coating modification 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 doping modification materials and coating modification 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, wherein The lithium-containing transition metal oxide includes nickel. 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 is 80%-96%.

12. The battery cell according to claim 1, wherein 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 the particles in the positive electrode film layer, the double peak positions 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, -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 5 N / m-75 N / 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 2,000 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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