A positive electrode material and a battery

Abstract

The application relates to the technical field of batteries and discloses a positive electrode material and a battery; wherein the positive electrode material comprises lithium nickel cobalt manganese oxide mixed with polycrystal particles and single crystal particles, the positive electrode material satisfies 2.0<=L<=10.0 and 0.2<=AZX<=0.5 at the same time; L is a shape factor calibration value of the lithium nickel cobalt manganese oxide obtained by an X-ray diffractometer and a diffraction spectrum analysis program; and AZX is a ratio of a difference value of a specific angle shape calibration value to a shape factor value at two maximum peak values. The positive electrode material in the application can not only improve the filling capacity to meet the energy density of the battery cell, but also can improve the structural stability of the positive electrode material, reduce the deterioration of the expansion and internal resistance, and thus improve the cycle life of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a cathode material and a battery. Background Technology

[0002] Lithium-ion batteries are widely used in electronics, communications, transportation, and other fields as an important energy storage device. Currently, the requirements for energy storage devices from mobile phones, electric vehicles, and other terminals are gradually increasing, making it a development trend to further improve the energy density, cycle performance, and lifespan of energy storage devices.

[0003] Among them, ternary cathode active materials have relatively high energy density, but their interface and bulk structure stability is poor during charging and discharging. They have problems such as side reactions with electrolyte, which cause cell expansion and thus affect battery life. Summary of the Invention

[0004] In view of this, the present invention provides a cathode material, a battery, and an electrical device that solves the problem that conventional ternary cathode active materials affect structural stability and thus reduce cell life when increasing energy density, effectively balancing the energy density and cycle life of lithium-ion batteries.

[0005] In a first aspect, the present invention provides a cathode material comprising lithium nickel cobalt manganese oxide, wherein the lithium nickel cobalt manganese oxide comprises polycrystalline particles, wherein the L and AZX of the polycrystalline particles simultaneously satisfy: 2.0≤L≤10.0, 0.2≤AZX≤0.5; Where L = K a max / A θ AZX = (A50 - A20) / 2K a max ; L is the shape factor calibration value of lithium nickel cobalt manganese oxide obtained by X-ray diffractometer and diffraction pattern analysis program; K a max It is the shape factor value at the maximum peak value, the shape factor value is K, K=Dβcosθ / λ, D is the interplanar spacing, β is the full width at half maximum, θ is the incident angle, and λ is the incident wavelength with the maximum peak value; A θ The standard deviation of the angle; AZX is the ratio of the difference between two shape calibration values ​​at a specific angle to the shape factor value at the maximum peak value; A50 is the shape factor value when the angle is 50°; A20 is the shape factor value when the angle is 20°.

[0006] In an alternative embodiment, the particle size Dv50 of the polycrystalline particles is 5 - 20 μm, preferably 8 - 15 μm; and / or, the powder compaction density of the polycrystalline particles is 3.3 - 3.5 g / cm 3 ; and / or, the specific surface area of the polycrystalline particles is 0.4 - 0.7 g / cm 2 .

[0007] In an alternative embodiment, the A θ is 0.1 - 0.4; and / or, the K a max is 0.6 - 1.3; and / or, the A50 is 2.7 - 3.1; and / or, the A20 is 2.1 - 2.4.

[0008] In an alternative embodiment, the lithium nickel cobalt manganese oxide further includes single crystal particles; The particle size Dv50 of the single crystal particles is 2 - 5 μm, and / or, the powder compaction density of the single crystal particles is 3.5 - 3.6 g / cm 3 , and / or, the specific surface area of the single crystal particles is 0.8 - 1.2 g / cm 2 .

[0009] Second, the present invention provides a battery, including a positive electrode sheet, a negative electrode sheet and an electrolyte. The positive electrode sheet includes the above positive electrode material; the chemical formula of the lithium nickel cobalt manganese oxide is: Li x Ni a Co b Mn c M 1-a-b-c O, where 1.0 < x < 1.04, 0.8 ≤ a < 1, 0 < b ≤ 0.1, 0 < c ≤ 0.1, and a + b + c = 1; the M element includes at least one of Zr, Y, Al, Ti, W, Sr, Ta, Mo, Nb, Na, K, Ca, Ce, La.

[0010] In an alternative embodiment, the electrolyte includes ethylene carbonate and a fluorine-containing additive. The mass content of ethylene carbonate in the electrolyte is less than 10%; the mass content of the fluorine-containing additive in the electrolyte is 3% - 10%.

[0011] In one optional embodiment, the positive electrode includes a current collector and an active layer disposed on the surface of the current collector. The current collector includes a base layer and a surface layer disposed on the base layer. The active layer includes a first active layer and a second active layer. The first active layer is disposed between the surface layer and the second active layer. The first active layer includes a first active material, which includes the polycrystalline particles and the single-crystal particles. The second active layer includes a second active material, which is composed of the single-crystal particles.

[0012] The thickness of the base layer is t1, and the thickness of the surface layer is t2; wherein, t1 = 3-10 μm, and / or, t2 = 0.5-2 μm; The thickness of the first active layer is A1, and the thickness of the second active layer is A2; wherein, A1 = 28-53 μm, and / or, A2 = 5-10 μm, and / or, 0.1 ≤ A2 / A1 ≤ 0.3; the base layer comprises one or more of polyethylene terephthalate, polypropylene, and polyimide; The surface layer includes a metallic aluminum layer. The positive electrode further includes a carbonaceous layer, which is located between the surface layer and the first active layer. The carbonaceous layer is made of at least one of carbon black, graphene, and carbon nanotubes.

[0013] Furthermore, the thickness of the carbonaceous layer is t3, which satisfies: t3 = 0.5-1.5 μm, and / or, 0.25 ≤ t3 / t2 ≤ 2. In a third aspect, the present invention also provides an electrical device including the aforementioned battery.

[0014] Beneficial effects: The cathode material of the present invention includes lithium nickel cobalt manganese oxide, wherein the lithium nickel cobalt manganese oxide comprises polycrystalline particles. Simultaneously, by controlling the L and AZX of the polycrystalline particles to satisfy: 2.0 ≤ L ≤ 10.0, 0.2 ≤ AZX ≤ 0.5, the filling capacity of the lithium nickel cobalt manganese oxide cathode material can be improved, and the particle distribution of the cathode material can be made more uniform. Uniform particle distribution improves the stress on the cathode material structure during high-temperature charge and discharge processes, thereby improving the structural stability of the lithium nickel cobalt manganese oxide cathode material and thus improving high-temperature cycle performance. In other words, the cathode material of the present invention not only improves the filling capacity to meet the energy density requirements of the battery cell, but also improves the structural stability of the cathode material, reduces expansion and internal resistance deterioration, thereby improving the cycle life of the battery cell. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a SEM image of the cathode material in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the positive electrode sheet in Embodiment 1 of the present invention. Attached image description: 1-Base layer, 2-Surface layer, 3-Carbonized layer, 4-First active layer, 5-Second active layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The embodiments of the present invention are described below in conjunction with the above-described scheme.

[0020] According to an embodiment of the present invention, in one aspect, a positive electrode material is provided, comprising lithium nickel cobalt manganese oxide, wherein the lithium nickel cobalt manganese oxide comprises polycrystalline particles, and the L and AZX of the polycrystalline particles simultaneously satisfy: 2.0≤L≤10.0, 0.2≤AZX≤0.5; Where L = K a max / A θ AZX = (A50 - A20) / 2K a max , L is the shape factor calibration value of lithium nickel cobalt manganese oxide obtained by X-ray diffractometer and diffraction pattern analysis program; K a maxThis is the shape factor value at the maximum peak value, which is obtained by multiplying the reciprocal of the incident wave with the maximum peak value by the product of the interplanar spacing and the full width at half maximum (FWHM) of the analyzed particles. The shape factor value is K, where K = Dβcosθ / λ, D is the interplanar spacing, β is the FWHM, θ is the incident angle which determines the "observation direction" of the X-rays, cosθ is the coefficient that converts the "oblique width" to the "vertical width," the FWHM β is the value measured in the "2θ direction," and λ is the wavelength of the incident wave with the maximum peak value. A θ The standard deviation of the angle; AZX is the ratio of the difference between two shape calibration values ​​at a specific angle to the shape factor value at the maximum peak value; A50 is the shape factor value when the angle is 50°; A20 is the shape factor value when the angle is 20°.

[0021] The aforementioned polycrystalline particles represent an aggregate formed by the aggregation of single-crystal particles through physical or chemical bonding. Single-crystal particles represent the primary structure of a single particle.

[0022] In this invention, L is the shape factor calibration value of lithium nickel cobalt manganese oxide obtained by X-ray diffraction (XRD) and diffraction pattern analysis program (jade). Because the particle arrangement structure can vary according to shape, the particle shape of the cathode material affects the ease of particle breakage and can also affect the particle filling capacity. Generally, when the particle shape factor calibration value increases, i.e., the larger L is, the closer the particles are to spheres. The stress generated by the material during charging and discharging can be released more evenly, reducing the risk of material breakage and thus reducing electrolyte damage to the particles. However, particles that are closer to spheres may be less advantageous in terms of electrode filling capacity, as they are more prone to forming gaps during filling, reducing the energy density of the battery. Conversely, a smaller L results in poorer particle sphericity, which can improve filling capacity but affects the structural stability of the material. The cathode active material is more prone to cracking or breakage during battery cycling, thus affecting the battery's cycle life. Therefore, in this invention, L is controlled at an appropriate value (2.0≤L≤10.0); on the one hand, it can improve the filling capacity of ternary cathode material particles to meet the energy density of the battery; on the other hand, it can improve the structural stability of the material, thereby improving the cycle life of the battery.

[0023] AXZ can be defined as the sphericity distribution coefficient, which is the ratio of the difference between two specific angular shape calibration values ​​to the shape factor at the maximum peak value. It reflects the overall distribution coefficient of large and small spherical particles. The sphericity distribution coefficient aims to consider the overall distribution of large and small spherical particles in the positive electrode polycrystalline particles. If the distribution is wide, there will be too many small spherical particles, which are more likely to undergo side reactions with the electrolyte, leading to slower mass transfer between particles, increased concentration polarization, worsened internal resistance of the cell, and increased expansion rate. If the distribution is narrower, it means higher particle size uniformity. Each cathode material particle has a similar lithium-ion insertion / extraction path length, resulting in synchronized reaction rates and reduced overall electrochemical polarization of the electrode. This helps minimize thermal effects caused by localized overload. However, if the particle size distribution is too narrow, the accumulation of particles will create numerous pores, making it difficult to increase the electrode's compaction density. Furthermore, micron-sized particles have longer solid-phase lithium-ion diffusion paths within them, which can compromise the electrode's kinetic performance at low temperatures or high rates. Additionally, narrower particle size distributions lead to higher production costs and more stringent equipment requirements, ultimately worsening the benefits. This invention controls AZX at an appropriate value (0.2 ≤ AZX ≤ 0.5), balancing production costs and equipment requirements while reducing internal resistance and expansion rate of the cell to improve cell lifespan while maintaining energy density.

[0024] By controlling the shape factor calibration value L of polycrystalline lithium nickel cobalt manganese oxide particles to satisfy 2.0≤L≤10.0, and the ratio AZX of the difference between two specific angle shape calibration values ​​to the shape factor value at the maximum peak value to satisfy 0.2≤AZX≤0.5, the polycrystalline lithium nickel cobalt manganese oxide particles have suitable roundness and uniform particle size distribution. When applied to the positive electrode sheet of a battery, this can improve the compaction density of the positive electrode sheet and construct a three-dimensional conductive network. During repeated charge and discharge of the battery, it ensures that the volume change of each particle is similar and the contact stress distribution between particles is uniform, significantly reducing particle breakage caused by local stress concentration, thereby improving the cycle life of the battery, especially the high-temperature cycle performance.

[0025] As an example, the L of the positive electrode material can be 2, 3, 4, 5, 6, 7, 8, 9, 10 or within any two of the above values; the AZX of the positive electrode material can be 0.2, 0.3, 0.4, 0.5 or within any two of the above values.

[0026] A θ The standard deviation is typically determined by XRD testing using standard samples for instrument calibration, such as single-crystal silicon (Si) and LaB6 (lanthanum hexaboride). θThe standard deviation is mainly obtained by subtracting the theoretical value from the measured value; the smaller the deviation, the better. In this embodiment, single-crystal silicon (Si) is used as the standard sample. The instrument angle is calibrated with the standard sample. An XRD is measured once with the Si standard sample to find its standard peak position (e.g., Si (111) 2θ≈28.44°). The angle deviation = measured 2θ Theoretical value 2θ; when measuring samples later, all peak positions are shifted and corrected using this difference; the theoretical value refers to the peak position of Si, which is an intrinsic characteristic value, and each material has its own characteristic peak value.

[0027] The L and AZX cathode materials are mainly achieved by adjusting parameters such as calcination temperature, precursor selection, gas displacement, and pH value during the synthesis process. The suitable calcination temperature is 500-550℃.

[0028] Furthermore, the particle size Dv50 of the polycrystalline particles is 5-20 μm, preferably 8-15 μm; and / or, the powder compaction density of the polycrystalline particles is 3.3-3.5 g / cm³. 3 ; and / or, the specific surface area of ​​the polycrystalline particles is 0.4-0.7 g / cm³. 2 Optimizing the particle size range of polycrystalline particles can better prevent side reactions and gas generation caused by particle breakage, and can also better prevent capacity and output characteristic problems caused by increased energy density and resistance.

[0029] As an example, the particle size Dv50 of the polycrystalline particles can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, or within any two of the above values. The powder compaction density of the polycrystalline particles can be 3.3 g / cm³. 3 3.4 g / cm 3 3.5g / cm 3 Or it may fall within the range of any two of the above values. The specific surface area of ​​the polycrystalline particles may be 0.4 g / cm³. 2 0.5 g / cm 2 0.6 g / cm 2 0.7g / cm 2 Or it falls within the range formed by any two of the above values.

[0030] Dv50 indicates the particle size that accounts for 50% of the total volume of particles in the volumetric particle size distribution, starting from the smallest particle size. In other words, particles smaller than this size constitute 50% of the total particle volume. The Dv50 is determined using a Malvern 2000 (MasterSizer 2000) laser particle size analyzer, following the standard procedure GB / T19077-2016 / ISO 13320:2009.

[0031] In one alternative implementation, the A θ The value is 0.1-0.4, preferably 0.15-0.3; and / or, the K a max The value of A50 is 0.6-1.3, preferably 0.9-1.1; and / or, the value of A50 is 2.7-3.1, preferably 2.8-3.0; and / or, the value of A20 is 2.1-2.4, preferably 2.2-2.3.

[0032] As an example, the A θ The value of K can be 0.1, 0.2, 0.3, 0.4, or within any two of the above values; a max The value can be 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or within any two of the above values; A50 can be 2.7, 2.8, 2.9, 3.0, 3.1 or within any two of the above values; A20 can be 2.1, 2.2, 2.3, 2.4 or within any two of the above values.

[0033] In one optional embodiment, the lithium nickel cobalt manganese oxide further includes single-crystal particles; the particle size Dv50 of the single-crystal particles is 2-5 μm, and / or the powder compaction density of the single-crystal particles is 3.5-3.6 g / cm³. 3 ; And / or, the specific surface area of ​​the single crystal particles is 0.8-1.2 g / cm³. 2 .

[0034] As an example, the particle size Dv50 of the single crystal particles can be 2μm, 3μm, 4μm, 5μm, or within any two of the above values; the powder compaction density of the single crystal particles can be 3.5 g / cm³. 3 3.55 g / cm 3 3.6g / cm 3 Or within the range of any two of the above values; the specific surface area of ​​the single crystal particle can be 0.8 g / cm³. 2 0.9 g / cm2 、1.0 g / cm 2 、1.1 g / cm 2 、1.2 g / cm 2 or within the range formed by any two of the above values.

[0035] The powder compaction density of the polycrystalline particles and single crystal particles can be obtained by testing with a powder compaction density meter. The specific surface area of the polycrystalline particles and single crystal particles can be obtained by testing with a Quadrasorb SI specific surface area tester.

[0036] In the present invention, the positive electrode active material includes single crystal lithium nickel cobalt manganese oxide and polycrystalline lithium nickel cobalt manganese oxide. By blending the single crystal particles with the polycrystalline particles, the presence of the single crystal particles can improve the compaction of the electrode sheet, thereby enhancing the energy density of the battery; the side reaction of the single crystal particles with the electrolyte at high temperature is less, which can improve the cycle performance of the battery; the presence of the polycrystalline particles can improve the rate performance of the electrode sheet; therefore, the positive electrode active material includes single crystal and polycrystalline lithium nickel cobalt manganese oxides. By controlling the Dv50, specific surface area, etc. of the single crystal particles and polycrystalline particles, the battery can maintain a high energy density while having superior rate performance and cycle performance.

[0037] In a second aspect, the present invention also provides a battery, including a positive electrode sheet, a negative electrode sheet and an electrolyte. The positive electrode sheet includes the above positive electrode material. The chemical formula of the lithium nickel cobalt manganese oxide is: Li x Ni a Co b Mn c M 1-a-b-c O, where 1.0 < x < 1.04, 0.8 ≤ a < 1, 0 < b ≤ 0.1, 0 < c ≤ 0.1, and a + b + c = 1; the M element includes at least one of Zr, Y, Al, Ti, W, Sr, Ta, Mo, Nb, Na, K, Ca, Ce, La. Using a high-nickel ternary material as the positive electrode material can obtain a lithium ion battery with a high energy density.

[0038] Furthermore, the positive electrode sheet includes a current collector and an active layer provided on the surface of the current collector. The current collector includes a base layer and a surface layer provided on the base layer. The active layer includes a first active layer and a second active layer. The first active layer is provided between the surface layer and the second active layer. The first active layer includes a first active material, and the first active material includes the polycrystalline particles and the single crystal particles; the second active layer includes a second active material, and the second active material is composed of the single crystal particles.

[0039] In the present invention, the lithium nickel cobalt manganese oxide in the first active layer includes polycrystalline particles and single crystal particles mixed therein. The advantage of mixing polycrystalline particles and single crystal particles is that it can improve the mechanical strength of the first active layer. The presence of single crystal particles can improve the compaction of the electrode sheet, thereby enhancing the energy density. The presence of polycrystalline particles can improve the rate performance of the electrode sheet, enabling the entire first active layer to possess the properties of high compaction and high rate. The lithium nickel cobalt manganese oxide in the second active layer is single crystal particles. Due to the stable structure of the single crystal lithium nickel cobalt manganese oxide, its high voltage resistance and high temperature resistance are more stable. Covering the surface of the first active layer can well prevent the first active layer from directly contacting the electrolyte, reduce the occurrence of side reactions, and improve the cycle and safety performance of the lithium ion battery.

[0040] Further, the positive electrode material includes a first active material having a single crystal structure and a second active material having a polycrystalline structure. The chemical formula of the first active material is: LixNi a Co b Mn c M1 1-a-b-c O2, and the chemical formula of the second active material is: LixNi a Co b Mn c M2 1-a-b-c O2, where 1.0 < x < 1.04, 0.8 ≤ a < 1, 0 < b ≤ 0.1, 0 < c ≤ 0.1, and a + b + c = 1; M1 and M2 are each independently selected from at least one of Zr, Y, Al, Ti, W, Sr, Ta, Mo, Nb, Na, K, Ca, Ce, and La.

[0041] In an optional embodiment, the electrolyte includes ethylene carbonate (EC) and a fluorine-containing additive. The mass content of ethylene carbonate in the electrolyte is less than 10%, and the mass content of the fluorine-containing additive in the electrolyte is 3 - 10%. The high-nickel ternary material (Ni content ≥ 80%) has extremely high surface activity at high temperatures, Ni 4+Exhibiting strong catalytic activity, the ethylene carbonate (EC) in the electrolyte undergoes continuous oxidative decomposition on the positive electrode surface. Furthermore, high-nickel ternary cathode materials experience particle breakage in the later stages of cycling, leading to the breakage of the CEI (cement in electrolyte) on the surface, which in turn causes oxidation of ethylene carbonate in the electrolyte, resulting in gas production and battery swelling. In this invention, by controlling the EC content in the electrolyte to below 10%, the total amount of EC that can be oxidized on the positive electrode surface is significantly reduced, directly suppressing gas production dominated by EC decomposition. Simultaneously, the reduced EC content also decreases the chance of it reacting with active oxygen released from the positive electrode at high temperatures, thereby alleviating gas production in the early stages of battery "thermal runaway." The fluorinated additive in this invention is added to the electrolyte at a mass content controlled at 3-10%, which facilitates the formation of a LiF-rich CEI film on the positive electrode surface. This interfacial film is thin, dense, and self-healing, passivating the catalytically active sites on the high-nickel surface, effectively inhibiting contact between the electrolyte and the active material, preventing particle breakage, and reducing battery swelling. This fluorinated additive is a conventional fluorinated additive used in electrolytes; for example, fluoroethylene carbonate can be directly used. Preferably, the ethylene carbonate content in the electrolyte is 2%-6% by mass, and the fluorinated additive content in the electrolyte is 4%-7% by mass.

[0042] As an example, the mass content of ethylene carbonate in the electrolyte can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or within any two of the above values; the mass content of the fluorinated additive in the electrolyte can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or within any two of the above values.

[0043] In one optional embodiment, the solvent in the electrolyte is a conventional electrolyte solvent, such as one or more selected from ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl formate (MF), methyl acetate (MA), methyl propionate (MP), ethyl acetate (EP), 1,3-propanesulfonate lactone (1,3-PS), ethylene sulfate (DTD), propylene sulfate (TS), ethylene sulfite (ES), diethyl sulfite (DES), γ-butyrolactone (BL), and dimethyl sulfoxide (DMSO). Preferably, one or more selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC).

[0044] Similarly, the lithium salt is a conventional lithium salt used in electrolytes, such as one or more of LiPF6, LiClO4, LiBF4, LiBOB, LiODFB, LiPO2F2, LiFSI, and LiTFSI. In a further preferred embodiment, LiPF6 is used as the primary lithium salt in this invention.

[0045] In addition to fluorinated additives, the additives in the electrolyte also include other conventional additives, such as any one or more of the following: vinylene carbonate (VC), vinyl sulfate (DTD), succinate (SN), adiponitrile (ADN), 1,3,6-hexanetrionitrile (HTN), p-fluorobenzonitrile, p-methylbenzonitrile, 1,3,5-pentanetricarbonitrile, 2-methylmaleic anhydride (citric acid anhydride), and ethylene glycol bis(propionitrile) ether (DENE).

[0046] In one optional embodiment, the thickness of the base layer is t1, and the thickness of the surface layer is t2; wherein, t1 = 3-10 μm, and / or, t2 = 0.5-2 μm; The thickness of the first active layer is A1, and the thickness of the second active layer is A2; wherein, A1 = 28-53 μm, and / or, A2 = 5-10 μm, and / or, 0.1 ≤ A2 / A1 ≤ 0.3.

[0047] As an example, the thickness t1 of the base layer can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or within any two of the above values; the single-sided thickness t2 of the surface layer can be 0.5μm, 1μm, 1.5μm, 2μm or within any two of the above values; the thickness A1 of the first active layer can be 28μm, 30μm, 35μm, 40μm, 45μm, 50μm, 53μm or within any two of the above values; the thickness A2 of the second active layer can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or within any two of the above values; and A2 / A1 can be 0.1, 0.15, 0.2, 0.25, 0.3 or within any two of the above values.

[0048] The positive electrode further includes a carbon layer located between the surface layer and the first active layer; the material of the carbon layer includes at least one of carbon black, graphene, and carbon nanotubes; the thickness of the carbon layer is t3, which satisfies: t3 = 0.5-1.5 μm, and / or, 0.25 ≤ t3 / t2 ≤ 2; As an example, t3 can be 0.5μm, 1μm, 1.5μm or within the range of any two of the above values, and t3 / t2 can be 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2 or within the range of any two of the above values.

[0049] In one optional embodiment, the base layer is composed of at least one of the polymer materials polyethylene terephthalate (PET), polypropylene (PP), and polyimide (PI); the surface layer is composed of a layer of metallic aluminum. Metallic aluminum has advantages such as good conductivity, strong stability, light weight, and low cost; therefore, using metallic aluminum for the surface layer can effectively collect and transport electrons from the positive electrode of the battery. Furthermore, the ternary high-nickel material of this invention has a relatively low ion diffusion rate, which can easily lead to problems such as excessive polarization and lithium deposition during fast charging. The metal layer in the current collector (polymer material + aluminum metal layer) of this invention has excellent conductivity, and the surface of the metal layer of the composite current collector is specially treated (such as roughness optimization and pre-coating), which can enhance the bonding force with the positive electrode coating, make the contact with the active material more uniform, reduce the ohmic impedance and interfacial impedance of the electrode, and reduce contact failure caused by interfacial peeling during cycling. At the same time, the polymer substrate has good flexibility and has a buffering effect to absorb part of the electrode expansion stress, suppress electrode cracking, adapt to the volume change of the high-nickel electrode under high current charging and discharging, reduce impedance fluctuation, thereby improving the rate performance of the battery and meeting the fast charging application scenarios of high-nickel batteries.

[0050] In this invention, the positive electrode active layer includes a first active layer 4 and a second active layer 5, and the positive electrode current collector includes a polymer base layer 1 and a metallic aluminum surface layer 2. The first active layer 4 is disposed between the surface layer 2 and the second active layer 5, and the first active layer 4 includes polycrystalline particles and single-crystal particles; the second active layer 5 is composed of the single-crystal particles. The present invention employs a combination of double-layer coating on the positive electrode and a composite current collector primarily because: high-nickel materials exhibit significant volume expansion during charging and discharging, which is the main cause of cycle decay and electrode cracking. The composite current collector's polymer base layer possesses a natural elastic modulus, allowing it to absorb some of the expansion stress when the positive electrode expands. The first active layer of the positive electrode includes single-crystal particles and polycrystalline particles. The single-crystal particles serve as a rigid framework, while the polycrystalline particles act as the capacity body. The single-crystal framework in the lower active layer enhances the bonding force with the flexible composite current collector. This structure utilizes the flexibility of the composite current collector to buffer macroscopic stress and the high mechanical strength of the lower single crystal to maintain the integrity of the coating's microstructure, significantly reducing the separation of the active material from the current collector in the high-nickel system during long cycles, thereby greatly improving cycle stability.

[0051] In one optional embodiment, the base layer and the surface layer disposed on the base layer constitute a composite current collector, the sheet resistance of the composite current collector is G mΩ / □, and G satisfies: 10≤G≤25; the low sheet resistance composite current collector of the present invention can reduce the occurrence of short circuits in the battery, improve the safety of the battery cell, and improve the energy density of the battery, thus meeting the requirements of fast charging of the battery.

[0052] As an example, the sheet resistance G of the composite current collector can be 10 mΩ / □, 11 mΩ / □, 13 mΩ / □, 15 mΩ / □, 17 mΩ / □, 19 mΩ / □, 21 mΩ / □, 23 mΩ / □, 25 mΩ / □, or within any two of the above values.

[0053] The sheet resistance G of the composite current collector is obtained by the following detection method: 1. Sample preparation: Cut the composite current collector into 100 mm × 100 mm square samples, ensuring that the sample surface is free of wrinkles, scratches, stains or damage to the conductive layer; if sampling from roll material, it should be cut at a distance of ≥50 mm from the edge to avoid edge effects affecting the test results.

[0054] 2. Instrument Calibration: Use a four-probe sheet resistance tester (such as RTS-8 or equivalent equipment), preheat for 30 minutes, and use a standard resistor with known sheet resistance, such as a standard resistor with 10.0 ohms per square (mΩ / □), to perform single-point calibration of the instrument and confirm that the test error is ≤±2%.

[0055] 3. Environmental control: The test environment temperature is controlled at 25±2 ℃ and the relative humidity is 45%–65% to avoid the influence of temperature and humidity changes on the resistivity of the conductive layer.

[0056] 4. Test Operation: Place the sample flat on the insulation test platform, ensuring that the sample is completely in contact with the platform without bubbles or warping. Adjust the four probes so that they are arranged in a straight line at equal intervals (1.0 mm between probes), and press them vertically and lightly onto the sample surface. Control the pressure at 0.5–1.0 N to avoid piercing the conductive layer. Five test points were selected sequentially at the center and four corners of the sample. Each point was tested three times, and the sheet resistance value (unit: mΩ / □) of each test was recorded.

[0057] 5. Data processing: Remove the maximum and minimum values ​​of each test point, and take the remaining 1 test value as the representative value of that point; then calculate the arithmetic mean of the 5 representative values ​​of the test points, which is the sheet resistance G of the composite current collector (unit: mΩ / □), and the result is retained to 1 decimal place.

[0058] In one alternative embodiment, the presence of the second surface layer in the positive electrode can effectively slow down the increase in ohmic impedance of the composite current collector caused by HF corrosion, so that the impedance P after application is only 1-3mΩ, thereby reducing the side effects caused by the increase in ohmic impedance.

[0059] Thirdly, the present invention also provides an electrical device including the battery described above.

[0060] Electrolyte The electrolyte of this invention comprises a solvent, a lithium salt, and additives. The types and amounts of the solvent, lithium salt, and additives are not particularly limited and can be selected from those conventionally used in the art. For example, the solvent may be ethylene carbonate (EC), dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, fluoroethylene carbonate, etc.; the lithium salt may be lithium hexafluorophosphate (LiPF6), lithium difluorophosphate, lithium bis(fluorosulfonyl)imide (LiFSI), etc.; and the additives may include EP, vinylene carbonate (VC), ethylene sulfate (DTD), etc. Wherein, the solvent contains ethylene carbonate, and the mass content of ethylene carbonate in the electrolyte is less than 10%, the additives include fluorinated additives; the mass content of the fluorinated additives in the electrolyte is 3-10%.

[0061] [Septum] The diaphragm of the present invention is a conventional diaphragm, such as PP diaphragm, PE diaphragm, etc.

[0062] [Positive Electrode Tablets] The positive electrode sheet of the present invention includes a positive electrode current collector and a positive electrode active layer coated on one or both surfaces of the positive electrode current collector. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active layer includes 95.9~97.6 wt% positive electrode active material, 1.5~2.6 wt% conductive agent, and 0.9~1.5 wt% binder. The positive electrode active layer can be one layer or two layers. The positive electrode current collector is a composite current collector, including a base layer 1 of polymer substrate, a surface layer 2 of aluminum metal layer disposed on the base layer 1, and a carbonaceous layer 3 disposed on the surface layer 2.

[0063] The positive electrode active material in this invention includes lithium nickel cobalt manganese oxide, which comprises polycrystalline particles, wherein the L and AZX of the polycrystalline particles simultaneously satisfy: 2.0≤L≤10.0, 0.2≤AZX≤0.5; the lithium nickel cobalt manganese oxide also includes single-crystal particles.

[0064] Polycrystalline Li x Ni a Co b Mn c M1 1-a-b-cThe method for preparing O2 includes: preparing a salt solution containing nickel, manganese, and cobalt sources into a total transition metal mixture according to the required proportions; adding deionized water as a base solution to a seed reactor, starting stirring (500-600 rpm), and adding NaOH solution dropwise to adjust the pH of the base solution to 11.0-11.5, while stabilizing the temperature at 70-75℃. Simultaneously, adding salt solution, NaOH solution, and ammonia water dropwise to the reactor, controlling the salt solution addition rate at 8-11 mL / min, and stabilizing the pH in the reactor at 10.8-11.0, so that the final target particle size Dv50 reaches 8-10 μm as a positive electrode active material precursor; then mixing the positive electrode active material precursor with lithium raw material and performing heat treatment. The heat treatment process includes: preheating at 550-600℃ for 4-6 hours to initially achieve lithiation and prevent particle agglomeration due to excessively high temperatures during the main calcination; followed by high-temperature calcination, with the calcination temperature controlled at 850-900℃ to promote the full insertion of Li+ into the crystal lattice; and finally, coating and sintering to form polycrystalline Li particles. x Ni a Co b Mn c M1 1-a-b-c O2.

[0065] Polycrystalline Li x Ni a Co b Mn c M1 1-a-b-c In the O2 preparation method, excessively high pH leads to rapid precipitation, while excessively low pH results in incomplete precipitation, both of which cause irregular particle morphology, thus affecting the L value. Additionally, the stirring speed and feeding rate are also important factors affecting the L and AZX values. Excessive speed breaks up the particles, resulting in smaller particle sizes; insufficient speed causes particle agglomeration, affecting the sphericity distribution. Simultaneously, a stable feeding rate of the metal salt solution allows particles to grow in a "layer-by-layer coating" manner, rather than forming new crystal nuclei. In the above preparation method of this application, the lithium raw material can be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or hydroxyoxide, but there are no particular limitations, as long as it is soluble in water. Specifically, the lithium raw materials can be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi or Li3C6H5O7, and any one or a mixture of two or more of them can be used.

[0066] This invention does not impose any particular limitation on the conductive agent in the positive electrode sheet, which may be selected from conductive agents conventionally used in the art, including but not limited to one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder. This invention also does not impose any particular limitation on the binder in the positive electrode sheet, which may be selected from binders conventionally used in the art, including but not limited to one or more of styrene-butadiene rubber latex, polytetrafluoroethylene latex, sodium carboxymethyl cellulose, sodium alginate, polyvinyl alcohol, polyacrylic acid, lithium polyacrylate, sodium polyacrylate, carboxylated chitosan, and polyvinylidene fluoride.

[0067] In the positive electrode sheet of the present invention, under the same positive electrode active material composition, the content and type of positive electrode active material, binder and thickener within the above-mentioned proportion range have no significant effect on the effect, and the content and type of conductive agent and binder will not be verified in subsequent embodiments.

[0068] Negative electrode plate The negative electrode sheet of the present invention includes a negative electrode current collector and a negative electrode active layer coated on one or both surfaces of the negative electrode current collector; the negative electrode active layer includes a negative electrode active material, a conductive agent, a binder and a thickener.

[0069] The negative electrode active material can be a conventional carbon negative electrode active material such as artificial graphite, or a silicon-doped negative electrode active material, such as silicon-carbon material. This invention does not particularly limit the types of conductive agents, binders, and thickeners in the negative electrode sheet; their selection range can refer to the types of conductive agents and binders in the positive electrode sheet. For example, the binders include styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyisobutylene (PIB), polyimide (PI), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and vinylidene fluoride. Tetrafluoroethylene One or more of propylene terpolymer and polymethyl methacrylate (PMMA); and / or, the conductive agent includes one or more of carbon nanotubes (CNT), Ketjen black (KB), mesophase carbon microspheres, vapor-deposited carbon fiber (VGCF), conductive carbon black (SP), conductive graphite, and acetylene black (AB); preferably, the conductive agent includes conductive carbon black and carbon nanotubes, the binder includes polyacrylic acid (PAA) and styrene-butadiene rubber (SBR), and the thickener includes carboxymethyl cellulose (CMC).

[0070] The lithium-ion battery provided by the present invention will be further described in detail below through specific embodiments.

[0071] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0072] According to an embodiment of the present invention, in another aspect, the present invention also provides an electrical device including the battery described above.

[0073] Example 1 A positive electrode material, the specific preparation process of which is as follows: According to LiNi 0.9 Co 0.05 Mn 0.04 Al 0.01 To meet the O2 ratio requirements, a solution containing nickel, manganese, aluminum, and cobalt sources was prepared into a salt solution containing a total transition metal mixture. Deionized water was added to the seed reactor as the base solution, and stirring was started (550 rpm). NaOH solution was added dropwise to adjust the pH of the base solution to 11.0, and the temperature was stabilized at 72℃. Simultaneously, salt solution, NaOH solution, and ammonia were added dropwise to the reactor, controlling the salt solution addition rate at 10 mL / min, and maintaining the pH of the reactor at 10.9 to obtain the precursor of the positive electrode active material. The positive electrode active material precursor and lithium raw material are then mixed and heat-treated. The heat treatment process is as follows: preheating at 580℃ for 5 hours to initially achieve lithiation and avoid particle agglomeration due to excessively high temperatures during the main calcination; followed by high-temperature calcination, with the calcination temperature controlled at 890℃, to ensure that Li+ is fully embedded into the crystal lattice. Finally, coating and sintering are performed to form K... a max =1.07 、 A θ Polycrystalline LiNi with A50=2.93 and A20=2.23 0.9 Co 0.05 Mn 0.04 Al 0.01 O2, such as Figure 1 As shown; the polycrystalline particles have L=5.63, AZX=0.33, and a compacted density of 3.57 g / cm³. 3 Specific surface area is 1.09 g / cm³ 2 The Dv50 is 3.34μm.

[0074] A compaction density of 3.41 g / cm³ was obtained using conventional single-crystal preparation processes. 3 Specific surface area is 0.53 g / cm³ 2 LiNi single-crystal particles with a Dv50 of 12μm 0.9 Co 0.05 Mn 0.04Al 0.01 O2.

[0075] A battery, the specific manufacturing process of which is as follows: 1. Preparation of the positive electrode, such as Figure 2 As shown: Nanoscale metallic aluminum is formed on the surface of a polymer PET film through vacuum evaporation and magnetron sputtering. The metal layer is then thickened by electroplating, followed by the coating of carbon layers on both sides of the metal layer. The PET film is 6 μm thick, with 1.2 μm thick aluminum layers on each side and 1.1 μm thick carbon layers on each side. Next, a positive electrode active slurry 1 is prepared by mixing polycrystalline particles, single-crystal particles, conductive carbon black (SP), carbon nanotubes, and polyvinylidene fluoride in a mass ratio of 87.3%:9.7%:0.5%:1.3%:1.2%, and coated onto the carbon layers on both sides to form the first active layer, with a thickness of 45 μm on each side. Finally, single-crystal LiNi particles in a mass ratio of 97%:0.5%:1.3%:1.2% are added. 0.9 Co 0.05 Mn 0.04 Al 0.01 O2, conductive carbon black (SP), carbon nanotubes and polyvinylidene fluoride are mixed to prepare positive electrode active slurry 2, which is coated on the surface of the first active layer on both sides to form a second active layer with a thickness of 8μm on each side; after drying, rolling and die cutting, positive electrode sheet is obtained.

[0076] 2. Preparation of negative electrode sheet: Artificial graphite, silicon oxide, conductive carbon black, CMC, and SBR are mixed in a weight ratio of 91.675%: 4.825%: 1%: 1.3%: 1.2%, deionized water is added, and a negative electrode slurry is obtained under vacuum stirring. The negative electrode slurry is uniformly coated on a copper foil current collector. After drying, rolling and die cutting, the negative electrode sheet is obtained.

[0077] 3. Preparation of electrolyte: In a reaction vessel filled with argon gas and containing <0.1 ppm water and <0.1 ppm oxygen, ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and propylene carbonate (PC) are mixed thoroughly. Fully dried lithium hexafluorophosphate (LiPF6) is then added, followed by the addition of fluorinated ethylene carbonate as a fluorine additive. Vinyl carbonate (VC) and ethylene sulfate (DTD) may also be added. The mixture is stirred thoroughly to prepare the electrolyte. The electrolyte contains 13% LiPF6, 5% fluoroethylene carbonate (FEC), 2% vinylene carbonate (VC), 1% ethylene sulfate (DTD), 3% ethylene carbonate (EC), 15% propylene carbonate (PC), and 40% dimethyl carbonate (DMC), with the remainder made up with ethyl methyl carbonate (EMC).

[0078] 4. Separator: PP separator, 16μm thick, 42% porosity, and 220s / 100mL air permeability; 5. Battery preparation: The positive electrode, negative electrode and separator obtained above are stacked in the order of positive electrode, separator and negative electrode, and then wound to obtain bare cell; the bare cell is placed in outer packaging and placed at 80°C for 12 hours, the prepared electrolyte is injected and sealed; after standing for 24 hours, a full cell is obtained.

[0079] Examples 2-14 and Comparisons 1-4 The difference between Embodiments 2-14 and Comparative Examples 1-4 of the present invention and Embodiment 1 above is that the positive electrode material and the structural composition of the positive electrode sheet are different, as shown in the table below.

[0080] Table 1

[0081] Table 2

[0082] In the examples and comparative examples in Table 1, parameters such as calcination temperature, precursor selection, gas displacement, and pH value during the synthesis process were adjusted to modify the polycrystalline LiNi particles in the cathode material. 0.9 Co 0.05 Mn 0.04 Al 0.01 O2 of K a max、 A θ A50, A20, L, AZX. For example: In Example 2 of this application, the stirring speed was adjusted to 540 rpm, the feeding rate to 9 mL / min, the pH to 10.8, the preheating temperature to 575℃, and the calcination temperature to 885℃; In Example 3 of this application, the stirring speed was adjusted to 560 rpm, the salt solution feeding rate to 9 mL / min, the pH to 11, the preheating temperature to 600℃, and the calcination temperature to 900℃; In Example 4 of this application, the stirring speed was adjusted to 500 rpm, the salt solution feeding rate to 8 mL / min, the pH to 10.7, the preheating temperature to 550℃, and the calcination temperature to 850℃; the preparation parameters of the cathode material in other examples will not be described in detail.

[0083] Examples 5-14 and Comparative Examples 1-4, not shown in Table 2 of this invention, have the same parameters as Example 1. In Example 2 of this invention, the mass content of ethylene carbonate in the electrolyte is 9%, and the content of the fluorinated additive fluoroethylene carbonate is adjusted to 3%; in Example 3 of this invention, the mass content of ethylene carbonate in the electrolyte is 2%, and the content of the fluorinated additive fluoroethylene carbonate is adjusted to 10%; the electrolytes in Examples 4-14 and Comparative Examples 1-4 are the same as those in Example 1.

[0084] Examples 15-20 The difference between Embodiments 15-20 of the present invention and Embodiment 1 above is that the values ​​of t1-t3 and A1-A2 in the positive electrode are different, as shown in the table below.

[0085] Table 3

[0086] In Example 19, no composite current collector is used; instead, conventional aluminum foil with a thickness of 12 μm is used. In Example 20, there is only one positive electrode active layer, which is prepared using the same monocrystalline and polycrystalline mixed positive electrode active slurry 1 as in Example 1.

[0087] Examples 21-24 The difference between Embodiments 21-24 of the present invention and Embodiment 1 above is that the compaction density, specific surface area, and Dv50 of the polycrystalline particles and single-crystal particles in the cathode material are different, as shown in the table below.

[0088] Table 4

[0089] The parameters not shown in this invention are the same as those in Example 1.

[0090] Experimental Example The prepared batteries from the examples and comparative examples were tested for specific capacity, cycle retention, and expansion rate. The specific testing process is as follows: 1. Battery capacity test In a constant temperature environment of 25°C, the batteries of the above embodiments and comparative examples were charged sequentially with a constant current of 0.33C to 4.25V, and then charged with a constant voltage of 4.25V until the current dropped to 0.05C; then discharged with 0.33C to 2.75V, and the charge and discharge were repeated twice; the discharge capacity of the second discharge was recorded as the initial capacity, and the specific capacity = the initial capacity of the battery (mAh) / the mass of the positive electrode active material (g).

[0091] 2. Capacity retention rate during 45℃ cycling The batteries corresponding to the above embodiments and comparative examples were placed in an environment of (45±2)℃ and left to stand for 2 hours. After 3 hours, when the battery body reaches (45±2)℃, the battery is charged at a constant current of 1C to the upper limit voltage of 4.25V, and then charged at a constant voltage until the current drops to 0.05C. After resting for 30 minutes, it is discharged at 1C to 2.75V. The discharge capacity C0 at this time is recorded. The aforementioned charge and discharge cycle is repeated for 50T. After the cycle is completed, Cx is recorded. The capacity retention rate after the cycle is obtained by calculating Cx / C0×100%.

[0092] 3. Cyclic expansion rate at 45℃ The initial cell was placed in an environment of (45±2)℃ and charged at a constant current and constant voltage of 0.33C to the upper limit voltage of 4.25V, with a cutoff current of 0.05C. After standing for 2 hours, the cell thickness was measured using a digital micrometer with an accuracy of not less than 0.01mm and a measuring surface diameter of not less than 10mm, and recorded as the initial thickness T0. After 50 cycles, the battery was removed from the testing equipment and placed at room temperature for 2 hours. It was then charged again at a constant current and constant voltage of 0.33C to the upper limit voltage of 4.25V, with a cutoff current of 0.05C. After standing for 2 hours, the cell thickness after the cycles was measured using the same instrument and testing method, and recorded as T1. The expansion rate is calculated as follows: Expansion rate (%) = (T1) / (T1) The result is calculated as T0) / T0×100%, and the result is rounded to two decimal places.

[0093] The verification results of the above experiment are shown in the table below.

[0094] Table 5

[0095] Table 6

[0096] As shown in the table above, by controlling the L and AZX of the polycrystalline particles to simultaneously satisfy: 2.0≤L≤10.0, 0.2≤AZX≤0.5, the filling capacity of the cathode material can be improved, and the energy density can be increased. Furthermore, while increasing or maintaining the energy density, the particle distribution of the cathode material can be made more uniform. The uniform particle distribution improves the stress of the structure during high-temperature charge and discharge processes, thereby improving structural stability, reducing gas production, reducing expansion rate, and thus improving high-temperature cycle performance.

[0097] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A positive electrode material, characterized in that, The material includes lithium nickel cobalt manganese oxide, which comprises polycrystalline particles, wherein the L and AZX of the polycrystalline particles simultaneously satisfy: 2.0≤L≤10.0, 0.2≤AZX≤0.5; Where L = K a max / A θ AZX = (A50 - A20) / 2K a max ; L is the shape factor calibration value of lithium nickel cobalt manganese oxide obtained by X-ray diffractometer and diffraction pattern analysis program; K a max It is the shape factor value at the maximum peak value, the shape factor value is K, K=Dβcosθ / λ, D is the interplanar spacing, β is the full width at half maximum, θ is the incident angle, and λ is the incident wavelength with the maximum peak value; A θ The standard deviation of the angle; AZX is the ratio of the difference between two shape calibration values ​​at a specific angle to the shape factor value at the maximum peak value; A50 is the shape factor value when the angle is 50°; A20 is the shape factor value when the angle is 20°.

2. The cathode material according to claim 1, characterized in that, The particle size Dv50 of the polycrystalline particles is 5-20 μm, preferably 8-15 μm; And / or, the compacted density of the polycrystalline particles is 3.3-3.5 g / cm³. 3 ; And / or, the specific surface area of ​​the polycrystalline particles is 0.4-0.7 g / cm³. 2 .

3. The cathode material according to claim 1 or 2, characterized in that, The A θ The value is 0.1-0.4, preferably 0.15-0.3; And / or, the K a max The value is 0.6-1.3, preferably 0.9-1.1; And / or, the A50 is 2.7-3.1, preferably 2.8-3.0; And / or, the A20 is 2.1-2.4, preferably 2.2-2.

3.

4. The cathode material according to any one of claims 1-3, characterized in that, The lithium nickel cobalt manganese oxide also includes single crystal particles; The single crystal particles have a particle size Dv50 of 2-5 μm, and / or the powder compaction density of the single crystal particles is 3.5-3.6 g / cm³. 3 And / or, the specific surface area of ​​the single crystal particles is 0.8-1.2 g / cm³. 2 .

5. A battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that, The positive electrode sheet includes the positive electrode material described in any one of claims 1-4, and the chemical formula of the lithium nickel cobalt manganese oxide is: Li x Ni a Co b Mn c M 1-a-b-c O, where 1.0 < x < 1.04, 0.8 ≤ a < 1, 0 < b ≤ 0.1, 0 < c ≤ 0.1, and a + b + c = 1; the M element includes at least one of Zr, Y, Al, Ti, W, Sr, Ta, Mo, Nb, Na, K, Ca, Ce, and La.

6. The battery according to claim 5, characterized in that, The electrolyte comprises ethylene carbonate and a fluorinated additive, wherein the mass content of ethylene carbonate in the electrolyte is less than 10%; and the mass content of the fluorinated additive in the electrolyte is 3%-10%.

7. The battery according to claim 5, characterized in that, The positive electrode includes a current collector and an active layer disposed on the surface of the current collector. The current collector includes a base layer and a surface layer disposed on the base layer. The active layer includes a first active layer and a second active layer. The first active layer is disposed between the surface layer and the second active layer. The first active layer includes a first active material, which includes polycrystalline particles and single-crystal particles. The second active layer includes a second active material, which is composed of single-crystal particles.

8. The battery according to claim 7, characterized in that, The thickness of the base layer is t1, and the thickness of the surface layer is t2; wherein, t1 = 3-10 μm, and / or, t2 = 0.5-2 μm; The thickness of the first active layer is A1, and the thickness of the second active layer is A2; wherein, A1 = 28-53 μm, and / or, A2 = 5-10 μm, and / or, 0.1 ≤ A2 / A1 ≤ 0.3; The base layer includes one or more of polyethylene terephthalate, polypropylene, and polyimide; The surface layer includes a layer of aluminum.

9. The battery according to claim 8, characterized in that, The positive electrode further includes a carbon layer, which is located between the surface layer and the first active layer; The carbonaceous layer is made of at least one of carbon black, graphene, and carbon nanotubes.

10. The battery according to claim 9, characterized in that, The thickness of the carbonaceous layer is t3, which satisfies: t3 = 0.5-1.5 μm, and / or 0.25 ≤ t3 / t2 ≤ 2.

Images