Positive electrode sheet, lithium-ion battery and electrical device

Abstract

A positive electrode sheet characterized in that it comprises a positive current collector and a positive electrode material applied to the positive current collector, wherein the positive electrode material contains a positive active material, the positive active material comprising a lithium manganese iron phosphate agglomerate and a ternary positive electrode material, wherein the positive electrode sheet satisfies: 0 ≤ S ⋅ R ≤ 30; where S represents a ratio of a peak area of ​​a diffraction peak of a (003)-crystal plane to a peak area of ​​a diffraction peak of a (102)-crystal plane in an XRD spectrum of the positive electrode material for a fully charged positive electrode sheet, and where R represents the roundness of the ternary positive electrode material.

Description

Technical field

[0001] The present invention relates to the field of battery technology, in particular to a positive electrode sheet, a lithium-ion battery and an electrical device. Technical background

[0002] Lithium manganese iron phosphate (LMFP) is widely used due to its advantages, such as a high voltage plateau, large theoretical specific capacity, and low price. LMFP aggregates are secondary particles formed by the aggregation of two or more primary particles and exhibit an aggregated state. Compared to non-agglomerated LMFP primary particles, the use of LMFP agglomerates can improve the solid-phase transfer capability of the positive electrode system and reduce the battery impedance. However, LMFP agglomerates have a relatively large particle size and are difficult to compact, which limits the increase in the packing density of the positive electrode sheet and results in a lower battery energy density. Content of the invention

[0003] The object of the present invention is to overcome the aforementioned shortcomings of the prior art and to provide a positive electrode sheet, a lithium-ion battery, and an electrical device. By controlling and regulating the ratio of a peak area of ​​a diffraction peak of a (003) crystal plane to a peak area of ​​a diffraction peak of a (102) crystal plane in an XRD spectrum of the positive electrode material when the positive electrode sheet is fully charged, and the roundness of the ternary positive electrode material, such that they satisfy a specific relationship, it is possible for the battery to simultaneously exhibit excellent energy density and cycle performance.

[0004] To solve the above-mentioned problem, the present invention provides, in a first aspect, a positive electrode sheet comprising a positive current collector and a positive electrode material applied to the positive current collector, wherein the positive electrode material contains a positive active material, the positive active material comprising a lithium-manganese-iron-phosphate agglomerate and a ternary positive electrode material, wherein the positive electrode sheet fulfills: 0≤S⋅R≤30; where S represents a ratio of a peak area of ​​a diffraction peak of a (003)-crystal plane to a peak area of ​​a diffraction peak of a (102)-crystal plane in an XRD spectrum of the positive electrode material for a fully charged positive electrode sheet, and where R represents the roundness of the ternary positive electrode material.

[0005] In a second aspect, the present invention provides a battery comprising the positive electrode sheet.

[0006] In a third aspect, the present invention provides an electrical device comprising the battery.

[0007] In comparison to the prior art, the advantageous effects of the present invention are as follows: By mixing or combining the LMFP agglomerate with the ternary positive electrode material, and by regulating the ratio of the peak areas of the diffraction peaks of the (003) crystal plane and the (102) crystal plane in the XRD spectrum of the positive electrode material when the positive electrode sheet is fully charged, and the roundness of the ternary positive electrode material such that they satisfy the above-mentioned specific relationship, the present invention achieves that the positive electrode sheet has a suitable density, whereby a battery containing this positive electrode sheet can exhibit both good energy density and good cycle performance. Images Fig. Figure 1 shows a schematic representation of the measurement method for the maximum inradius R. iand the minimum circumradius R c a particle of a ternary positive electrode material. Description of embodiments

[0008] To clarify the tasks, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in these embodiments are described clearly and completely below. Obviously, the described embodiments represent only a subset of the embodiments of the present invention and do not encompass all possible embodiments. All other embodiments that could be obtained by a person skilled in the art, without inventive effort, based on the embodiments in the present invention, fall within the scope of protection of the present invention.

[0009] In the present invention, technical features that are openly described include both closed technical solutions consisting of the listed features and open technical solutions that contain the listed features.

[0010] In the present invention, unless otherwise specified, a numerical range is considered continuous and includes the minimum and maximum values ​​of that range, as well as every value between these minimum and maximum values. Furthermore, if a range refers to integers, it includes every integer between the minimum and maximum values ​​of that range. In addition, if several ranges are provided to describe features or properties, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein are to be understood as including all subranges contained therein.

[0011] In the present invention, the specific procedures for dispersion and stirring are not particularly limited.

[0012] The reagents or instruments used in the present invention, the manufacturer of which is not specified, are conventional products that are commercially available.

[0013] In the present invention, expressions such as "first time" and "second time" and the like do not serve to limit the number. Positive electrode sheet

[0014] The present invention provides a positive electrode sheet comprising a positive current collector and a positive electrode material applied to the positive current collector, wherein the positive electrode material contains a positive active material, the positive active material comprising a lithium manganese iron phosphate agglomerate and a ternary positive electrode material, wherein the positive electrode sheet fulfills: 0≤S⋅R≤30; where S represents a ratio of a peak area of ​​a diffraction peak of a (003)-crystal plane to a peak area of ​​a diffraction peak of a (102)-crystal plane in an XRD spectrum of the positive electrode material for a fully charged positive electrode sheet, and where R represents the roundness of the ternary positive electrode material.

[0015] The LMFP agglomerates have a relatively large particle size, and when compacted, the gaps between them are relatively large, preventing the formation of a high compaction density. The ternary positive electrode material exhibits a good degree of crystal plane slippage and can fill the gaps between the LMFP agglomerates, thereby increasing the compaction density of the positive electrode material. Simultaneously, the roundness of the ternary positive electrode material also influences the compaction density; the higher the roundness, the more uniform the force distribution, which contributes to improving the compaction density of the positive electrode material. However, the compaction density should not be too high, as this would result in poor wettability of the positive electrode material and high polarization during a cycle, negatively impacting the battery's cycle performance.Therefore, if S·R is too small, the packing density of the positive electrode material is too low, which negatively impacts the battery's energy density; if S·R is too large, the packing density is too high, which negatively impacts the battery's cycle performance. It must be ensured that S·R is within a suitable range to achieve a balance between energy density and cycle performance.

[0016] S = S(003) / S(102). Here, S(003) and S(102) represent areas of the diffraction peak of the (003) crystal plane and the (102) crystal plane, respectively, in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet, where the units of S(003) and S(102) are equal. The (003) crystal plane reflects the layered structure features of the material along the c-axis, while the (102) crystal plane is related to the overall crystal structure of the material and reflects the atomic arrangement along the a- and c-axes. A sharp and strong (003) peak indicates that the material has a good layered structure, which is conducive to the intercalation and ejection of lithium ions and thus improves the cycle stability of the material.However, an excessively high (003) peak intensity can compromise the crystal structure stability of the entire material; under high external pressure, lattice deformations or structural distortions can occur, adversely affecting the electrochemical performance of the material. Therefore, the intensity of the (102) diffraction peak must be appropriately regulated to ensure that the ternary material enhances the lithium ion insertion and removal capacity (to improve cycle performance) while simultaneously exhibiting better crystal plane slippage (to improve compaction). By adjusting this ratio, the ternary positive electrode material can better fill the gaps between the LMFP agglomerates, thereby increasing the packing density of the positive electrode material and improving the battery's energy density.

[0017] The value of the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet can be regulated by adjusting a pH value and / or a temperature, an ammonia concentration, etc. in a nucleation phase during the production of the ternary positive electrode material.

[0018] In the present invention, the method for verifying the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet is not restricted. A person skilled in the art can verify the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet using conventional technical means. By way of example, the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet can be verified by the following method:

[0019] In an environment at room temperature (e.g. 25 °C, the same applies below), one battery terminal is clamped into a holder of a Lanhe (Blue Electric) charging and discharging system, charged at a rate of 0.33 C up to a cut-off voltage of 4.3 V, and then switched to constant voltage charging with a cut-off current rate of 0.05 C, bringing the battery to a fully charged state; subsequently, the battery is disassembled to obtain a positive electrode sheet.

[0020] The positive electrode sheet is soaked in DMC (dimethyl carbonate) at room temperature (e.g., 25 °C, the same applies in the following) for 60 minutes, then removed and dried. The positive electrode material on the surface of the current collector is scraped off and then ground using a ball mill until its particle size reaches a fineness greater than 360 mesh, i.e., until no granularity is perceptible to the touch. This yields a sample powder.

[0021] 2.0 g of the sample powder e are taken and subjected to an XRD test using an X-ray diffractometer (Rigaku Ultima IV from Rigaku, Japan). The specific test conditions are: Cu target, scan voltage 40 kV, current 40 mA, scan range 10° to 90°, scan speed 10° / min. The XRD is calibrated using a method with an internal silicon standard.

[0022] In the XRD spectrum, a diffraction peak at a position of a diffraction angle 2θ of 38° ± 0.6° is the diffraction peak of the (102) crystal plane, and a diffraction peak at a position of a diffraction angle 2θ of 18° ± 2° is the diffraction peak of the (003) crystal plane; their peak areas are designated as S(102) and S(003) respectively and have the same unit; and the ratio of these two peak areas gives the value S.

[0023] The roundness R of the ternary positive electrode material is calculated based on the average ratio of the maximum inradius to the minimum circumradius of the particles of the ternary positive electrode material. The higher the value of the roundness R of the ternary positive electrode material, the greater the roundness of the ternary positive electrode material, the more uniform the force distribution on the ternary positive electrode material, and the more advantageous this is for the compaction of the positive electrode material.

[0024] The roundness value R of the ternary positive electrode material can be regulated by adjusting the grinding speed and / or time, the sintering heating rate, etc., during the manufacture of a final product.

[0025] The present invention does not restrict the method for verifying the roundness R of the ternary positive electrode material. A person skilled in the art can verify the roundness R of the ternary positive electrode material using conventional technical means. By way of example, the roundness R of the ternary positive electrode material can be verified by the following method:

[0026] A fully discharged battery is taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet is soaked in DMC at room temperature for 60 minutes, then removed and dried. The positive electrode material on the surface of the current collector is scraped off. Conductive tape is applied to a sample stage of a scanning electron microscope (SEM); the positive electrode material powder is then evenly sprinkled onto the conductive tape. The sample stage is then placed in the scanning electron microscope, which is set to a magnification of 30 kx to obtain a high-magnification SEM image of the positive electrode powder. The SEM image is imported into the IPP software to determine the roundness of the particles in the SEM image. The calculation principle is described in Fig. Figure 1 shows the roundness R of the ternary positive electrode material.i and the minimum circumradius R c of the particle is calculated according to the following formula:

[0027] R = R i / R c , where R i and R c are specified in the same unit, which can be nm.

[0028] Methods for differentiating between a ternary positive electrode material and LMFP: 1.Differentiation based on morphology: The ternary positive electrode material is a single-crystal or single-crystal-like (quasi-single-crystal) structure; a single crystal has no secondary structure and a Dv50 value of 0.5 µm to 1.5 µm; although a quasi-single-crystal has a secondary structure, the primary particles within it are larger than those of LMFP; the particle size of the primary particles of LMFP is typically in the range of 50 nm to 180 nm, while the particle size of the primary particles of the ternary positive electrode material is typically greater than 300 nm; at the same time, the particle size of LMFP agglomerates is typically larger than the single-crystal-like particle size of the ternary positive electrode material; therefore, the single-crystal-like structure of the ternary positive electrode material contains larger primary particles in smaller numbers, while the structure of the LMFP agglomerates contains smaller primary particles in larger numbers.2. Differentiation based on the energy spectrum: Compared to LMFP, the ternary positive electrode material has more Ni and Co elements, and the two materials are distinguished by EDS (energy dispersive X-ray spectroscopy) analysis.

[0029] The ratio of the peak areas of the diffraction peaks of the (003) crystal plane and the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet, and the roundness of the ternary positive electrode material, both influence the energy density and cycle performance of the battery to varying degrees and are mutually interdependent. It is difficult to achieve both good energy density and good cycle performance by controlling a single variable. By mixing the LMFP agglomerate with the ternary positive electrode material, or...By combining the above specific relationship and regulating the ratio of the peak areas of the diffraction peaks of the (003) crystal plane and the (102) crystal plane in the XRD spectrum of the positive electrode material when the positive electrode sheet is fully charged, and the roundness of the ternary positive electrode material, the present invention achieves that the positive electrode sheet has a suitable density, enabling a battery containing this positive electrode sheet to have both good energy density and good cycle performance.

[0030] For example, the value of S·R can be chosen as 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, 26, 28, 30 or as a range formed by any two of the above values.

[0031] In one of the preferred embodiments, the positive electrode sheet satisfies: 16.8 ≤ S·R ≤ 23.2. The value of S·R is controlled within this specific range to better balance the energy density and cycle performance of the battery.

[0032] In some embodiments, the value of S lies in a range from 15 to 32, e.g. 15, 17, 20, 22, 24, 26, 28, 30, 32; alternatively, it lies in a range formed by any two of the above values.

[0033] In one of the preferred embodiments, the value of S lies in a range of 20 to 25.

[0034] If S is in the range of 15 to 32, especially in the range of 20 to 25, the ternary positive electrode material can achieve a more suitable packing density by filling the gaps between the LMFP agglomerates, thereby allowing the battery to maintain better cycle performance while achieving a higher energy density.

[0035] In some embodiments, the value of R lies in a range from 0.4 to 1, e.g. 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1; alternatively, it lies in a range formed by any two of the values ​​mentioned above.

[0036] In one of the preferred embodiments, the value of R lies in a range of 0.6 to 0.98.

[0037] If R is in the range of 0.4 to 1, particularly in the range of 0.6 to 0.98, the ternary positive electrode material can achieve a more suitable packing density by filling the gaps between the LMFP agglomerates, thereby allowing the battery to maintain better cycle performance while achieving a higher energy density.

[0038] In some embodiments, the positive electrode sheet further satisfies 32 ≤ S·d ≤ 320, where d represents the Dv50 particle size of the lithium manganese iron phosphate agglomerate and is given in µm. For example, S·d can be chosen to be 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, or a range formed by any two of the above values.

[0039] In one of the preferred embodiments, the positive electrode sheet further satisfies: 108 ≤ S·d ≤ 158.

[0040] The inventors further discovered during their research that the smaller the Dv50 particle size of the LMFP agglomerates, the more pores are present between the LMFP agglomerates, and the smaller these pores are. To further improve the packing density of the positive electrode material, ternary positive electrode materials with a better degree of slip are required so that they can penetrate the pores. By controlling the S·d value in the range of 32 ≤ S·d ≤ 320, particularly in the range of 108 to 158, the positive electrode material achieves a more suitable packing density, thus improving the balance between the battery's energy density and cycle performance, and ultimately improving its overall performance. If S·d is too small, there are too many pores between the LMFP agglomerates, and the ternary material cannot adequately or completely fill these pores. These pores then negatively impact the packing density and, consequently, the battery's performance.If the value of S·d is too large, the pores between the positive electrode materials are too large, and under the influence of greater external pressure, material deformations or structural distortions may occur.

[0041] The value of the Dv50 particle size (dh, d) of the LMFP agglomerates can be regulated by adjusting the secondary sintering temperature, spray conditions, etc.

[0042] The present invention does not restrict the method for verifying the Dv50 particle size of the LMFP agglomerates. A person skilled in the art can verify the Dv50 particle size of the LMFP agglomerates using conventional technical means. An exemplary test method for the Dv50 particle size of the LMFP agglomerates is as follows:

[0043] A fully discharged battery is taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet is dried, and 0.1–0.2 g of the positive electrode material powder is collected using a scraper. The collected positive electrode material powder is photographed using a scanning electron microscope (SEM) (GeminiSEM 300) at a magnification of 1 kx. The size of the LMFP agglomerates within the positive electrode material powder in the SEM image is measured using MEARSURE NANO software. The size of the LMFP aggregate particles is determined using a diagonal method. Once the collected sample quantity reaches 100 or more, the particle size distribution is statistically evaluated, and the particle size-related parameter Dv50 of the LMFP agglomerates is calculated.

[0044] In some embodiments, d is 2.5 to 10 µm. For example, d can be chosen to be 2.5 µm, 3 µm, 3.5 µm, 4 µm, 4.5 µm, 5 µm, 5.5 µm, 6 µm, 6.5 µm, 7 µm, 7.5 µm, 8 µm, 8.5 µm, 9 µm, 9.5 µm, 10 µm, or a range formed by any two of the above values.

[0045] In one of the preferred embodiments, d is 4.2 to 6.8 µm.

[0046] If d is in the range of 2.5 to 10 µm, especially in the range of 4.2 to 6.8 µm, the positive electrode material achieves a more suitable compression density, thus improving the balance between energy density and cycle performance of the battery.

[0047] In some embodiments, the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary positive electrode material is 1:(0.05 to 20), such as 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:2, 1:3, 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20; alternatively, it lies in a range formed by any two of the above values.

[0048] If the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary positive electrode material is within the above-mentioned suitable range, the combination of these two materials ensures that the positive electrode material achieves a more suitable energy density and that the energy density and cycle performance of the battery are better balanced.

[0049] The present invention does not restrict the method for verifying the mass ratio of lithium manganese iron phosphate agglomerate to ternary positive electrode material. A person skilled in the art can verify the mass ratio of lithium manganese iron phosphate agglomerate to ternary positive electrode material using conventional technical means. For example, the mass ratio of lithium manganese iron phosphate agglomerate to ternary positive electrode material can be measured by elemental composition analysis (ICP), such as:

[0050] A fully discharged battery is taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet is soaked in DMC at room temperature for 60 minutes, then removed and dried. The positive electrode material on the surface of the current collector is scraped off. 0.2 g of the positive electrode material sample is placed in a centrifuge tube, into which a total of 15 ml of aqua regia is added batchwise using a pipette to initiate dissolution. Once the sample is completely dissolved, 40 ml of deionized water is added to the centrifuge tube to dilute it. The resulting solution is transferred to a 100 ml volumetric flask, into which deionized water is further added until the solution is titrated to the label. This solution is then shaken well. Finally, approximately 40 ml of the solution is withdrawn using a 50 ml centrifuge tube for the ICP test.The instrument used is an inductively coupled plasma emission spectrometer (model: ICP-OES Thermo Fisher ICPPRO).

[0051] In some embodiments, the ternary positive electrode material is selected from at least one of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.

[0052] In some embodiments, the chemical formula of the ternary positive electrode material is LiNi. a Co b Q (1-a-b) O2 where the element Q is at least one of Mn and Al, where a is in the range of 0.1 to 0.92, such as 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.63, 0.65, 0.67, 0.70, 0.73, 0.75, 0.77, 0.80, 0.83, 0.85, 0.87, 0.90, 0.92 or is in a range formed by any two of the values ​​mentioned above; where b is in the range of 0.05 to 0.35, such as 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.220, 0.240, 0.260, 0.280, 0.3, 0.32, 0.35 or is in a range formed by any two of the above values.

[0053] The ternary positive electrode material may either contain no dopants or contain one dopant M. The present invention does not restrict the type of dopant M in the ternary positive electrode material. For example, it may be selected as at least one of titanium, tin, tantalum, niobium, or lanthanide metals.

[0054] The ternary positive electrode material can be selected as primary particles, as secondary particles (consisting of two or more primary particles) or as a mixture of primary and secondary particles.

[0055] In some embodiments, the Dv50 particle size of the ternary positive electrode material is 0.5 to 4.5 µm, such as 0.5 µm, 1.5 µm, 1.8 µm, 2.1 µm, 2.4 µm, 2.7 µm, 3.0 µm, 3.3 µm, 3.6 µm, 3.9 µm, 4.2 µm, 4.5 µm; alternatively, it lies within a range formed by any two of the above values. The present invention does not restrict the method for verifying the Dv50 particle size of the ternary positive electrode material. A person skilled in the art can verify the Dv50 particle size of the ternary positive electrode material using conventional technical means. The Dv50 particle size of the ternary positive electrode material is tested using the following procedure as an example:

[0056] A fully discharged battery is taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet is dried, and 0.1–0.2 g of the positive electrode material powder is collected using a scraper. The collected positive electrode material powder is photographed using a scanning electron microscope (SEM, model: GeminiSEM 300). The size of the ternary positive electrode material within the powder in the SEM image is measured using MEARSURE NANO software. The particle size of the ternary positive electrode material is determined using the diagonal method. Once the collected sample quantity reaches 100 or more, the particle size distribution is statistically evaluated, and the particle size-related parameter Dv50 of the ternary positive electrode material is calculated.

[0057] The present invention does not limit the manufacturing process of the ternary positive electrode material. A person skilled in the art can produce the ternary positive electrode material using conventional technical means. By way of example, the manufacturing process of the ternary positive electrode material comprises the following steps:

[0058] A precursor of a ternary positive electrode material, a lithium source and a source of a dopant M (if present) are mixed and dispersed, and subsequently sintered to obtain the ternary positive electrode material.

[0059] The precursor of the ternary positive electrode material contains Ni, Co, and Q in a stoichiometric target ratio. The precursor of the ternary positive electrode material is one or more of the hydroxides, oxides, and carbonates of Ni, Co, and Q. For example, the precursor of the ternary positive electrode material is a hydroxide of Ni, Co, and Q.

[0060] The precursor of the ternary positive electrode material can be obtained by methods known in the field, for example, by a co-precipitation process, a gel process, or a solid-state process. As an example, the manufacturing process of the precursor of the ternary positive electrode material comprises the following steps:

[0061] Nucleation process: A nickel source, a cobalt source, and a fluorine source are dispersed in a solvent to obtain a mixed solution. This mixed solution, a strong alkaline solution, and a complexing agent solution are combined and simultaneously pumped into a first reactor equipped with a stirrer. The pH of the reaction solution is controlled to 11.5 to 12.8, and the ammonia concentration to 0.4 to 0.6 mol / L. The reactor temperature is 40 to 60 °C, the stirring speed is 4 to 6 m / s, and the reaction is carried out under an inert atmosphere. After 2 to 4 hours of reaction, a crystal nucleation slurry is obtained.

[0062] Growth process: The resulting crystal nucleation slurry, a strong alkaline solution, and a complexing agent solution are mixed and simultaneously pumped into a second reactor equipped with a stirrer. The pH of the reaction solution is controlled to 10–11, and the ammonia concentration to 0.4–0.6 mol / L. The reactor temperature is 45–50 °C, the stirring speed is 4–6 m / s, and the reaction is carried out under a nitrogen atmosphere. After 6–8 hours of reaction, a solid-liquid separation is performed. The resulting solid is washed and dried to obtain a hydroxide containing Ni, Co, and Q. This yields the precursor of the ternary positive electrode material. The amount of S can be controlled during the nucleation phase by adjusting the pH and / or temperature, etc.

[0063] During the nucleation process, the Ni source used includes, but is not limited to, at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, or nickel acetate.

[0064] During the nucleation process, the co-source used includes, but is not limited to, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, or cobalt acetate.

[0065] During the nucleation process, the Q source used comprises at least one Mn source and one Al source. For example, the Mn source includes, but is not limited to, at least one of the following materials: manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese acetate; the Al source includes, but is not limited to, at least one of the following materials: aluminum hydroxide, aluminum chloride, aluminum oxide, aluminum sulfate.

[0066] If, during the nucleation process, the Ni source, the Co source, and the Q source are dispersed in a solvent, the solvent used includes, but is not limited to, water.

[0067] During the nucleation and growth process, the alkalis in the strong alkaline solution used each independently comprise at least one of sodium hydroxide and potassium hydroxide.

[0068] During the nucleation and growth process, the complexing agent solutions used include ammonia water.

[0069] In the production of the precursor of the ternary positive electrode material, the amounts of the Ni source, Co source and Q source used can be chosen so that they satisfy: Molar amount of Ni element : Molar amount of Co element : Molar amount of Q element = (92 to 10):(5 to 35):(3 to 85).

[0070] In the manufacture of the ternary positive electrode material, the Li source used includes, but is not limited to, at least one of the following materials: lithium oxide (Li2O), lithium phosphate (Li3PO4), lithium dihydrogen phosphate (LiH2PO4), lithium acetate (CH3COOLi), lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium nitrate (LiNO3).

[0071] In the production of the ternary positive electrode material, the amounts of the precursor of the ternary positive electrode material and the lithium source satisfy: Molar amount of the Li element : Sum of the molar amounts of the elements Ni, Co and Q = (0.99 to 1.09):1.

[0072] In the production of the ternary positive electrode material, the sintering atmosphere during sintering is an oxygen-containing atmosphere, for example an air atmosphere or an oxygen atmosphere; whereby the sintering can be chosen as single sintering or as double sintering.

[0073] If the sintering process during the production of the ternary material is a simple sintering process, the sintering temperature can be set to 650–1000 °C, the duration to 8–12 hours, and the heating rate to 0.5–10 °C / min. R can be regulated by controlling the grinding speed and / or time, the sintering heating rate, etc., during the production of the final product. S can be regulated by controlling the pH value and / or temperature, the ammonia concentration, etc., during the nucleation phase of the production of the ternary positive electrode material.

[0074] If the sintering process during the production of the ternary positive electrode material involves two sintering steps, the specific sintering steps include:

[0075] First, a first sintering and grinding process is carried out, followed by a second sintering process. During the first sintering, the temperature can be set to 450–800 °C and the duration to 4–8 hours. Ball milling can be selected as the milling method, with a ball-to-material ratio (mass ratio, the same applies in the following) of 1:(0.2–5), a ball milling speed of 300–750 rpm, and a milling duration of 5–14 hours. For the second sintering, the temperature can be set to 650–1000 °C and the duration to 5–10 hours. The heating rate for both sintering processes can be set to 0.5–10 °C / min. R can be regulated during the production of the final product by controlling the milling speed and / or time, the sintering heating rate, etc. S can be controlled by adjusting the pH value and / or temperature, the ammonia concentration, etc.in the nucleation phase during the production of the ternary positive electrode material are regulated.

[0076] A ball mill mixer or a high-speed mixer can be used for mixing and dispersing the precursor of the ternary positive electrode material, the lithium source, and the source of the dopant element M (if present). The source of the dopant element M can be selected from titanium, tin, niobium, tantalum, lanthanide metals, etc., to obtain a ternary positive electrode material containing a specific amount of dopant.

[0077] Furthermore, the precursor of the ternary positive electrode material can also be subjected to a coating process. Specifically, a coating material is applied to the surface of the positive active material using a dry coating process (high-temperature solid-state process), whereby the surface of the positive active material is partially or completely covered with a coating layer formed by the coating material. The coating layer contains at least one element (hereinafter referred to as the "coating element") selected from: aluminum (Al), phosphorus (P), silicon (Si), titanium (Ti), tungsten (W), boron (B), cobalt (Co), or yttrium (Y).

[0078] In some embodiments, the chemical formula of the lithium manganese iron phosphate agglomerates is: LiMn c Fe 1-cPO4, where 0 < c < 1, where c is e.g. 0.01, 0.03, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.93, 0.96, 0.99 or lies in a range formed by any two of the above values.

[0079] The lithium manganese iron phosphate agglomerate can either contain no dopants or contain one dopant element Z. The present invention does not limit the type of dopant Z in the lithium manganese iron phosphate agglomerate. For example, it can be selected as at least one of Ti, Mg, V, W, etc.

[0080] In one of the embodiments, the surface of the lithium-manganese-iron-phosphate agglomerate is partially or completely covered with a carbon layer.

[0081] The present invention does not restrict the manufacturing process of the lithium manganese iron phosphate agglomerate. A person skilled in the art can produce the lithium manganese iron phosphate agglomerate using conventional technical means. By way of example, the manufacturing process of the lithium manganese iron phosphate agglomerate comprises the following steps:

[0082] Dissolving a manganese source and an iron source in water, adding a carbonate solution, reacting, collecting the precipitate, washing, drying to obtain a Mn and Fe containing carbonate, which yields a precursor;

[0083] Mixing the obtained precursor, a lithium source, a phosphorus source and a first carbon source, grinding, first sintering and cooling to obtain a simply sintered material;

[0084] Mixing and dispersing the resulting single-sintered material, a dispersant, and a second carbon source in water, milling, spray drying, second sintering, cooling, washing, and drying to obtain the lithium manganese iron phosphate agglomerates. The Dv50 value (i.e., d) of the lithium manganese iron phosphate agglomerates can be regulated by adjusting the spray pressure, feed rate, and / or solids content of the slurry, etc., during the spray drying process.

[0085] For example, the manganese source used in the production of the Mn and Fe carbonate includes, but is not limited to, at least one of the following materials: manganese nitrate, manganese sulfate, manganese chloride, manganese acetate; and / or, the iron source used includes, but is not limited to, at least one of the following materials: iron(II) acetate, iron(II) sulfate; and / or, the carbonate used includes, but is not limited to, at least one of the following materials: sodium carbonate, potassium carbonate.

[0086] In the production of the Mn and Fe-containing carbonate, the molar ratio of Mn element in the manganese source used to Fe element in the iron source used can be chosen as (0.05 to 0.95):(0.95 to 0.05).

[0087] In the production of the simply sintered material, the lithium source used includes, but is not limited to, at least one of the following materials: lithium carbonate, iron phosphate, iron(II) phosphate, iron hydroxide, iron(II) hydroxide, iron carbonate, iron(II) carbonate, iron acetate, iron(II) acetate, iron(II) oxalate, iron oxalate; and / or, the phosphorus source used includes, but is not limited to, at least one of the following materials: lithium dihydrogen phosphate, lithium phosphate, diammonium hydrogen phosphate, ammonium phosphate; and / or, the first carbon source used includes, but is not limited to, at least one of the following materials: Glucose (GLC), Sucrose, Polyethylene Glycol (PEG), Polyvinyl Alcohol.

[0088] In the production of the simply sintered material, the molar amount of the Li element in the lithium source used can be chosen as 1.01 to 1.08 times the total molar amount of the elements Mn and Fe in the precursor, while the molar amount of the P element in the phosphorus source used can be chosen as 1.002 to 1.05 times the total molar amount of the elements Mn and Fe in the precursor.

[0089] In the production of the simply sintered material, the mass of the first carbon source can be chosen to be 4% to 5%, calculated on the basis of the total mass of the obtained precursor, the lithium source and the phosphorus source.

[0090] When producing the simply sintered material, ball milling can be chosen as the milling method, whereby the ball-material ratio can be chosen as 1:(0.2 to 5), the speed of ball milling can be chosen as 300 to 750 rpm, and the milling time of ball milling can be chosen as 2-8 h.

[0091] During the production of the simply sintered material, the temperature can be selected as 450 to 600 °C, the duration as 6 to 12 h, and the heating rate as 2 to 15 °C / min.

[0092] In the production of simply sintered material, the sintering atmosphere is an inert atmosphere, for example nitrogen or a noble gas (such as helium, argon, etc.).

[0093] In the production of lithium manganese iron phosphate agglomerates with the simply sintered material, the dispersant comprises, but is not limited to, at least one of the following materials: polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol; and / or, the second carbon source used includes, but is not limited to, at least one of the following materials: Glucose (GLC), Sucrose, Polyethylene Glycol (PEG), Polyvinyl Alcohol.

[0094] When producing lithium manganese iron phosphate agglomerates with the simply sintered material, the residual carbon content in the lithium manganese iron phosphate agglomerates can be selected as 1 wt.% to 3 wt.%.

[0095] When producing lithium manganese iron phosphate agglomerates with the simply sintered material, ball milling can be chosen as the milling method, whereby the ball-material ratio can be chosen as 1:(0.2 to 5), the speed of ball milling can be chosen as 300 to 750 rpm, and the milling time of ball milling can be chosen as 2 to 8 h.

[0096] During the production of lithium manganese iron phosphate agglomerates with the simply sintered material, the sintering temperature can be selected as 650 to 1000 °C, the duration as 8 to 12 h and the heating rate as 2 to 15 °C / min.

[0097] When producing lithium manganese iron phosphate agglomerates with a double-sintered material, the spray pressure can be selected as 0.4 to 0.8 MPa.

[0098] In the production of lithium manganese iron phosphate agglomerates using the simply sintered material, the sintering atmosphere is an inert atmosphere, for example nitrogen or a noble gas (such as helium, argon, etc.).

[0099] Additionally, in the production of lithium manganese iron phosphate agglomerates, a specific amount of a dopant source (if available) can be mixed with the precursor, the lithium source, the phosphorus source, and the initial carbon source as required. Dopant sources include, for example, a vanadium source (such as vanadium pentoxide), a tungsten source (such as ammonium metatungstate), a titanium source (such as titanium oxide), a magnesium source (such as magnesium carbonate), etc., to obtain LMFP agglomerates containing a specific amount of dopant.

[0100] In a manufacturing process of lithium manganese iron phosphate agglomerates, the carbon source can be added in two steps as described above; alternatively, the carbon source can be added only during the second sintering process, while no carbon source is added in the production of the simply sintered material.

[0101] In some embodiments, the mass fraction of the positive active material in the positive electrode material is 94% to 97.5%, such as 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, or lies in a range formed by any two of the above values.

[0102] In addition to the positive active material mentioned above, the positive electrode material also contains a conductive agent and a binder.

[0103] The conductive material in the positive electrode material serves to provide conductivity. Any conductive material can be used without particular restriction, as long as it exhibits suitable electronic conductivity and does not cause significant adverse chemical changes in the battery. Examples of conductive materials in the positive electrode material include, but are not limited to, at least one of the following: carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, and fullerenes. For example, carbon fiber could be carbon nanofiber, etc., while carbon black could be SP (Super P, the same applies hereafter), acetylene carbon black, Ketjen black, etc.

[0104] In some embodiments, the mass fraction of the conductive medium in the positive electrode material is 0.5% to 2.0%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or lies in a range formed by any two of the above values.

[0105] The binder in the positive electrode material serves to improve the adhesion between particles of the positive active material, as well as the adhesion between the positive active material and the positive current collector. Any binder can be used without particular restriction, provided it exhibits suitable binder properties and does not cause significant adverse chemical changes in the battery. Examples of binders in the positive electrode material include, but are not limited to, fluorinated polyolefin binders. Fluorinated polyolefin binders include, but are not limited to, polyvinylidene fluoride (PVDF), vinylidene fluoride copolymers, or their modified derivatives (e.g., modified with carboxylic acid, acrylic acid, acrylonitrile, etc.).

[0106] In some embodiments, the mass fraction of the binder in the positive electrode material is 1% to 4.0%, such as 1%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.7%, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, or lies in a range formed by any two of the above values.

[0107] The positive electrode material can be applied to one side of the positive current collector or to both sides of the positive current collector.

[0108] In the present invention, the positive current collector is not particularly restricted, as long as it is conductive and does not cause any adverse chemical changes in the battery. The positive current collector can, for example, consist of aluminum, nickel, titanium, stainless steel, burnt carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.

[0109] The positive electrode sheet according to the present invention can be produced using conventional methods in the field. For example, the positive active material, the conductive agent, and the binder are dispersed in a solvent to obtain a positive electrode slurry. The positive electrode slurry is then applied to at least one side of the positive current collector, and after operations such as drying, rolling, and cutting, the positive electrode sheet is obtained. The solvent comprises, but is not limited to, at least one of the following materials: N-methylpyrrolidone (NMP), deionized water. battery

[0110] The present invention further provides a battery comprising a positive electrode sheet, a negative electrode sheet and an electrolyte.

[0111] The negative electrode sheet according to the invention comprises a negative current collector and a negative electrode material applied to at least one surface of the negative current collector, wherein the negative electrode material contains a negative active material.

[0112] In the present invention, the negative active material is not specifically limited. By way of example, the negative active material comprises, but is not limited to, at least one of the following materials: natural graphite, synthetic graphite, mesophase carbon microspheres (MCMB), hard carbon, soft carbon, silicon, SiO₂ e (0 < e < 2, for example e = 1), silicon-carbon, Li4Ti5O 12 .

[0113] In some embodiments, the mass fraction of the negative active material in the negative electrode material is 94% to 97.5%, such as 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, or lies in a range formed by any two of the above values.

[0114] The negative electrode material may also contain a conductive agent and / or a binder.

[0115] The conductive material in the negative electrode material serves to provide conductivity. Any conductive material can be used without particular restriction, as long as it exhibits suitable electronic conductivity and does not cause significant adverse chemical changes in the battery. Examples of conductive materials in the negative electrode material include, but are not limited to, at least one of the following: carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, and fullerenes. For example, carbon fiber could be carbon nanofiber, and carbon black could be, for example, SP, acetylene black, Ketjen black, etc.

[0116] In some embodiments, the mass fraction of the conductive medium in the negative electrode material is 0.4% to 2%, such as 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or lies in a range formed by any two of the above values.

[0117] The binder in the negative electrode material serves to improve the adhesion between particles of the negative active material, as well as the adhesion between the negative active material and the negative current collector. Any binder can be used without particular restriction, provided it has suitable binder properties and does not cause significant adverse chemical changes in the battery. For example, the binder in the negative electrode material includes, but is not limited to, at least one of the following materials: carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, and water-based acrylic resin.

[0118] In some embodiments, the mass fraction of the binder in the negative electrode material is 1.0% to 4.5%, such as 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.7%, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, 4.2%, 4.5%, or lies in a range formed by any two of the above values.

[0119] The negative electrode material can be applied to one side of the negative current collector or to both sides of the negative current collector.

[0120] In the present invention, the negative current collector is not particularly restricted, as long as it is conductive and does not cause any adverse chemical changes in the battery. The positive current collector can, for example, consist of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with at least one of carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy.

[0121] The electrolyte according to the invention can be selected from various electrolytes suitable for batteries. The electrolyte comprises an electrolyte salt and a solvent, wherein the electrolyte salt typically comprises a lithium salt.

[0122] The lithium salt may include, but is not limited to, at least one of the following materials: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiP-O2F2), lithium difluorodioxalatophosphate (LiDFOP), lithium tetrafluorooxalatophosphate (LiTFOP). The concentration of the electrolyte salt in the electrolyte can be selected between 0.5 and 5 mol / L.

[0123] The solvent may, but is not limited to, at least one of the following materials: ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sulfone (ESE). The mass fraction of the solvent in the electrolyte can be selected between 70% and 98%.

[0124] Furthermore, the electrolyte may also contain 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 to improve the battery's high-temperature performance, overcharge performance, or low-temperature performance. For example, the high-temperature performance additives may be selected from at least one of DMOHC (2,5-dioxahexanedicarboxylic acid dimethyl ester), 1,4-butane sultone, 1,3-propane sultone, etc., with the mass fraction of the high-temperature performance additives in the electrolyte being 0 to 1.5%. The overcharge performance additives may be selected from at least one of lithium difluorophosphate, lithium difluorooxalatophosphate, etc.The additives for improving the battery's overcharge performance may be selected, with the mass fraction of the additives for improving the battery's overcharge performance in the electrolyte being 0 to 1.5%; the additives for improving the battery's low-temperature performance may be selected from at least one of fluoroethylene carbonate, lithium difluorobisoxalatoborate, etc., with the mass fraction of the additives for improving the battery's low-temperature performance in the electrolyte being 0 to 1.5%.

[0125] The battery may further include a separator located between the positive and negative electrode plates, which serves to separate the positive and negative electrode plates and prevent a short circuit caused by contact between them. The separator may be made of any separator material suitable for battery applications. By way of example, the separator may include, but is not limited to, at least one of polypropylene or polyethylene. Electrical device

[0126] The present invention further provides an electrical device with a battery. The battery serves as a power supply for the electrical device.

[0127] The term "electrical device" refers to any device that can utilize electrical energy and convert it into mechanical energy, thermal energy, light energy, or one or more other forms of energy, such as electric motors, electrothermal machines, electric light sources, etc. Specifically, it can include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Mobile devices can include mobile phones, laptops, drones, robotic vacuum cleaners, electronic cigarettes, etc. Electric vehicles can include pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.

[0128] The present invention will now be explained in more detail using specific exemplary embodiments. Example 1

[0129] This embodiment provides a lithium-ion battery whose specific manufacturing process is as follows: (1) Production of a positive electrode sheet (1.1) Production of a ternary positive electrode material

[0130] S1. Nucleation phase: According to the molar ratios of the respective elements Ni, Co, Q in the chemical formula LiNi a Co b Q (1-a-b)Nickel sulfate, cobalt sulfate, and manganese sulfate were weighed out and dispersed in water to obtain a mixed solution. The resulting mixed solution was transferred to a first reactor, and nitrogen was introduced as a protective gas. A 3.5 mol / L aqueous NaOH solution was added to adjust the pH of the reaction solution; the specific pH of the reaction solution is listed in Table 1. Simultaneously, 8 mol / L aqueous ammonia was added to adjust the ammonia concentration of the reaction solution to 0.4 mol / L. The temperature in the reactor (i.e., the nucleation temperature) is listed in Table 1. The linear stirring speed was 5 m / s. By controlling the flow ratios of the mixed solution, the aqueous NaOH solution, and the aqueous ammonia, the pH and the ammonia concentration in the reactor were kept stable.After continuous reaction for 4 hours, a crystal nucleation slurry was obtained.

[0131] S2. Growth Phase: The crystal nucleation slurry was transferred to a second reactor, and nitrogen was introduced as a protective gas. A 3.5 mol / L aqueous NaOH solution was added to adjust the pH of the reaction solution to 10.5. Simultaneously, 8 mol / L aqueous ammonia was added to adjust the ammonia concentration of the reaction solution to 0.4 mol / L. The reactor temperature was 50 °C, and the stirring speed was 4.5 m / s. By controlling the flow ratio of the crystal nucleation slurry, the aqueous NaOH solution, and the aqueous ammonia, the pH and ammonia concentration in the reactor were kept stable, allowing the crystal nuclei to grow stably. After a reaction time of 8 hours, the mixture was centrifuged, and the resulting solid was washed and dried to remove Ni. a Co b Q(1-a-b) (OH)2 (a=0.8, b=0.1, Q-element is Mn) was obtained. Thus, a precursor of the ternary positive electrode material was obtained.

[0132] S3. The precursor of the ternary positive electrode material, lithium hydroxide and magnesium oxide, were placed in a mixer and mixed. Based on the sum of the molar amounts of Ni, Co, and Q in the precursor of the ternary positive electrode material, the molar amount of Li in the lithium hydroxide was calculated to be 1.02 times the sum of the molar amounts. The resulting material was then transferred to an atmospheric furnace for a first sintering. The temperature of the first sintering was 750 °C, the duration of the first sintering was 10 hours, and the heating rate was 2.5 °C / min to obtain a simply sintered material.

[0133] S4. The resulting simply sintered material was ball-milled. The ball-to-material ratio was 1:1.2, the ball-milling speed was 500 rpm, and the milling time is listed in Table 1. The resulting material was then transferred back into an atmospheric furnace for a second sintering. The temperature of the second sintering was 800 °C, the duration of the second sintering was 8 hours, and the heating rate is listed in Table 1 to obtain the ternary positive electrode material. (1.2) Production of LMFP agglomerates

[0134] S1. According to the molar ratio of Mn and Fe in the chemical formula LiMn c Fe 1-c Manganese sulfate and iron(II) sulfate were weighed out and dissolved in deionized water using PO4 (c=0.6). Simultaneously, a 2 mol / L Na₂CO₃ solution was added. The reaction was carried out under stirring, the precipitate was collected, and after washing and drying, a Mn₂ solution was prepared. c Fe1-c CO3 precursor (c=0.6) obtained.

[0135] S2. The Mn c Fe 1-c CO3 precursors, Li2CO3, NH4H2PO4, and polyvinyl alcohol were mixed and placed in a ball mill and milled for 5 hours. The ball-to-material ratio was 1:1.2, and the milling speed was 500 rpm. The resulting material was then transferred to a reaction furnace for initial sintering. The sintering process was calculated based on the total molar amounts of Mn and Fe in the Mn. c Fe 1-cCO3 precursor, the molar quantity of Li in the lithium source used was 1.05 times higher, and the molar quantity of P in the phosphorus source used was 1.02 times higher. Calculated based on the total mass of the obtained precursor, the lithium source, and the phosphorus source, the mass of the first carbon source was 5%. A nitrogen atmosphere was maintained at all times in the sintering furnace, the sintering temperature was 500 °C, and the heating rate was 5 °C / min. After sintering for 10 hours, the material was cooled to room temperature to obtain a simply sintered material.

[0136] S3. The obtained single-sintered material, the dispersant (polyvinylpyrrolidone), and the carbon source (polyvinyl alcohol) were dispersed in deionized water and shot-milled. The shot-to-material ratio was 1:1.5, the shot-milling speed was 500 rpm, and the shot-milling time was 6 hours. The resulting material was then spray-dried at a feed rate of 4.5 m / s and a spray pressure as listed in Table 1. This material was then transferred to a sintering furnace for a second sintering process, the sintering temperature of which is listed in Table 1, lasting 10 hours at a heating rate of 8 °C / min. After cooling, washing, and drying, lithium manganese iron phosphate agglomerates were obtained. (1.3) Creating a positive electrode sheet

[0137] The lithium-manganese-iron-phosphate agglomerates, the ternary positive electrode material, the carbon black as a conductor, and the PVDF as a binder described above were mixed in a mass ratio of 76.8:19.2:2:2. NMP was then added as a solvent. The resulting material was stirred and dispersed under the action of a vacuum mixer to obtain a positive electrode slurry.

[0138] The positive electrode slurry was applied to two surfaces of an aluminum foil, which acts as the positive current collector, dried at room temperature, then transferred to an oven for further drying, and subsequently cold-pressed and cut to obtain a positive electrode sheet. (2) Production of a negative electrode sheet

[0139] A silicon-carbon composite material (silicon by mass 50%, the silicon being amorphous nanosilicon), graphite, carbon black as a conductor, SBR, and PAA as binders were mixed in a mass ratio of 23:73:1:2:1 (the silicon-carbon composite and the graphite formed the negative active material; the particle sizes Dv90, Dv50, and Dv10 of the resulting negative active material were 12 µm, 8.5 µm, and 5.3 µm, respectively). Deionized water was added as a solvent. The resulting material was stirred and dispersed under vacuum mixing to obtain a negative electrode slurry.

[0140] The negative electrode slurry was applied to two surfaces of a copper foil acting as a negative current collector, dried at room temperature, then transferred to an oven for further drying, and subsequently cold-pressed and cut to obtain a negative electrode sheet. (3) Preparation of an electrolyte

[0141] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 3:5:2 to obtain a mixed organic solvent. The dry lithium salt LiPF6 was then dissolved in this mixed organic solvent. Dimethyl 2,5-dioxahexanedicarboxylic acid ester (DMOHC) was then added to prepare an electrolyte with a LiPF6 concentration of 1 mol / L and a DMOHC mass fraction of 1.5%. (4) Manufacturing a separator

[0142] A polyethylene (PE) separator was used. (5) Assembly, Formation

[0143] The positive electrode sheet, separator, and negative electrode sheet described above were stacked sequentially, with the separator positioned between the positive and negative electrode sheets to provide insulation. These were then wound to form a bare cell. The bare cell was placed in an outer packaging sleeve, dried, and subsequently filled with electrolyte. Following processes such as vacuum sealing, settling, forming, and shaping, a lithium-ion battery was obtained. The specific forming steps were as follows:

[0144] Charging the battery with a constant current of 0.02 C to 20% of the state of charge (SOC);

[0145] Charging at a constant current of 0.33C to 80% of SOC;

[0146] Charging with a constant current of 0.1C to 90% of SOC;

[0147] Charging with a constant current of 0.2 C to 4.25 V, switching to constant voltage charging, cut-off current 0.05 C. Examples 2 to 23 and comparative examples 1 to 4

[0148] These embodiments and comparative examples each provided a lithium-ion battery. The manufacturing process is similar to that in embodiment 1, and differs from it in the following ways: (a) In the manufacturing process of the ternary positive electrode material: the pH of the reaction solution and the nucleation temperature in step S1, as well as the grinding time of the ball milling and the heating rate in step S4, which are listed in Table 1; (b) In the manufacturing process of the LMFP agglomerates: the spray pressure and the second sintering temperature in step S3, which are listed in Table 1; Furthermore, in embodiment 3: a=0.1, b=0.1, Q-element is Mn, c=0.9; In embodiment 4: a=0.5, b=0.2, Q-element is Al, c=0.1; In embodiments 15 and 21, other process conditions were also adapted, see Table 2. Table 1 Production of the ternary positive electrode material Production of LMFP agglomerates pH value of the reaction solution in step S1 Temperature of the reaction solution in step S1 / °C Sintering heating rate in step S4 / °C / min Grinding time of ball grinding in step S4 / h Sintering temperature in step S3 / °C Spray pressure in step S3 / MPa Example 1 12,0 45 2,5 9 800 0,6 Example 2 11,7 42 2 10 850 0,6 Example 3 12,2 48 3 10,5 700 0,6 Example 4 12,2 48 2,5 14 750 0,6 Example 5 12,4 48 2 14 750 0,6 Example 6 12,8 54 2 12 1000 0,6 Example 7 12,1 45 2 13 750 0,6 Example 8 12,8 58 2 9 1000 0,8 Example 9 11,8 45 3 10 800 0,4 Example 10 12,4 48 2,5 9 700 0,8 Example 11 11,7 40 2,5 12 1000 0,8 Example 12 11,8 42 2 10 650 0,6 Example 13 12,0 48 2 9 700 0,6 Example 14 12,0 46 2,5 10 850 0,6 Example 15 12,0 45 2,5 7,5 850 0,4 Example 16 12,8 58 3 5 1000 0,4 Execution aid- 12,8 48 2 9 850 0,4 game 17 Example 18 12,0 46 2 9 850 0,6 Example 19 12,0 46 2 10 750 0,6 Example 20 12,0 45 2,5 10 900 0,6 Example 21 12,8 56 2,5 12 1000 0,8 Example 22 12,8 52 2,5 12 950 0,6 Example 23 12,0 48 2 14 800 0,6 Comparative example 1 12,8 60 2,5 6 850 0,8 Comparative example 2 11,6 40 3 7,5 750 0,6 Comparative example 3 12,5 50 2,5 11 800 0,8 Comparative example 4 11,5 40 3 6 900 0,6 Table 2 Production of the ternary material Production of LMFP agglomerates Ammonia concentration of the reaction solution in step S1 (m / s) Grinding time of ball milling in step S3 (h) Feed rate during the spraying process of step S3 (m / s) Example 15 0,4 2 3 Example 21 0,6 8 6

[0149] The following procedures were used to verify the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet, the roundness R of the ternary positive electrode material, and the Dv50 particle size (dh d) of the lithium manganese iron phosphate agglomerate in each embodiment and comparison example. The test results are listed in Table 2.

[0150] (1) Verification of the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet: In an environment at room temperature (25 °C), the battery terminal was clamped in a holder of a Lanhe (Blue Electric) charging and discharging system, charged at a rate of 0.33 C up to a cut-off voltage of 4.3 V, and then switched to constant voltage charging with a cut-off current rate of 0.05 C to bring the battery to a fully charged state; subsequently, the battery was disassembled to obtain the positive electrode sheet.

[0151] The positive electrode sheet is soaked in DMC at room temperature (25 °C) for 60 minutes, then removed and dried. The positive electrode material on the surface of the current collector is scraped off and then ground using a ball mill until its particle size reaches a fineness greater than 360 mesh, i.e., until no granularity is perceptible to the touch. This yields a sample powder.

[0152] 0.5 g of the sample powder e is taken and subjected to an XRD test using an X-ray diffractometer (Rigaku Ultima IV from Rigaku, Japan). The specific test conditions are: Cu target, scan voltage 40 kV, current 40 mA, scan range 10° to 90°, scan speed 10° / min. The XRD is calibrated using a method with an internal silicon standard.

[0153] In the XRD spectrum, a diffraction peak at a position of a diffraction angle 2θ of 38° ± 0.6° is the diffraction peak of the (102) crystal plane, and a diffraction peak at a position of a diffraction angle 2θ of 18° ± 2° is the diffraction peak of the (103) crystal plane; their peak areas are designated as S(102) and S(103) respectively and have the same unit; and the ratio of these two peak areas gives the value S.

[0154] (2) Verification of the roundness R of the ternary positive electrode material: A fully discharged battery was taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet was soaked in DMC at room temperature for 60 minutes, then removed and dried. The positive electrode material on the surface of the current collector was scraped off. Conductive tape was applied to a sample stage of a scanning electron microscope (SEM); the powder of the positive electrode material was then evenly sprinkled onto the conductive tape. The sample stage was then placed in the scanning electron microscope, the magnification of which was set to 30 kx to obtain a high-magnification SEM image of the positive electrode powder. The SEM image was imported into the IPP software to determine the roundness of the particles in the SEM image. The calculation principle is described in Fig.Figure 1 shows the roundness R of the ternary positive electrode material. The roundness R was calculated by measuring the maximum inradius Ri and the minimum circumradius Rc using the particle measurement information according to the following formula: R = R i / R c , where R i and R c Both are given in nm.

[0155] (3) Dv50 particle size (dh d) of the lithium manganese iron phosphate agglomerate: A fully discharged battery was taken and disassembled to obtain a positive electrode sheet. The positive electrode sheet was dried, and 0.1 g of powder of the positive electrode material was collected using a scraper. The collected powder of the positive electrode material was photographed using a scanning electron microscope (SEM). The size of the LMFP agglomerates in the powder of the positive electrode material in the SEM image was measured using MEARSURE NANO software. The size of the LMFP aggregate particles was determined using a diagonal method. After the collected sample quantity reached 100 or more, the particle size distribution was statistically evaluated, calculating the particle size-related parameter Dv50 of the LMFP agglomerates.

[0156] The positive electrode sheets or lithium-ion batteries provided in the respective embodiments and comparative examples were subjected to performance tests. The test results are listed in Table 2. The specific test procedures were as follows:

[0157] Compressed density: 2.0 g of the positive electrode material sample were precisely weighed. Then, a lower seal, the sample, and an upper seal were successively inserted into the interior of a test mold. This mold was placed in a pressure system, and the machine automatically applied pressure up to the set pressure (3T) and held it for 10 seconds. The powder compressed density data could be read from the system (device model: PCD-2000).

[0158] Cycle performance test: The LAND system was used to perform the cycle performance test of the lithium-ion battery. The lithium-ion battery was charged and discharged at room temperature (25 °C) under conditions of a charge / discharge rate of 1 C / 1 C, a cutoff current of 0.05 C, and a voltage range of 2.5 to 4.3 V for 1000 cycles. After completion of the cycles, the cycle data were processed to obtain the capacity maintenance rate (battery capacity maintenance rate after n cycles = discharge capacity in the nth cycle / discharge capacity in the first cycle × 100%). Table 3 S R S·R d / µm S·d Density (g / cm³) 3 ) Battery capacity retention rate after 1000 cycles at 25 °C (%) Example 1 22,78 0,756 17,22 5,45 124,15 2,48 82,5 Example 2 20,03 0,901 18,05 5,64 112,97 2,51 83,1 Example 3 23,97 0,852 20,42 4,96 118,89 2,49 82,4 Example 4 24,96 0,672 16,77 6,32 157,75 2,52 82,5 Example 5 24,72 0,94 23,24 4,39 108,52 2,42 81,7 Example 6 21,27 0,835 17,76 6,74 143,36 2,55 82,3 Example 7 20,05 0,976 19,57 5,87 117,69 2,48 82,1 Example 8 28,65 0,811 23,24 4,75 136,09 2,42 78,5 Example 9 21,64 0,834 18,05 7,02 151,91 2,38 79,8 Example 10 24,85 0,758 18,84 6,68 166,00 2,36 77,8 Example 11 20,21 0,929 18,78 4,58 92,56 2,38 76,2 Example 12 20,86 0,857 17,88 4,72 98,46 2,40 75,2 Example 13 16,93 0,998 16,90 5,07 85,84 2,36 72,9 Example 14 31,46 0,534 16,80 7,25 228,09 2,35 74,1 Example 15 22,72 0,773 17,56 7,54 171,31 2,31 72,6 Example 16 31,59 0,535 16,90 8,52 269,15 2,32 72,8 Example 17 17,62 0,968 17,06 2,59 45,64 2,27 73,1 Example 18 24,92 0,967 24,10 5,21 129,83 2,25 71,9 Example 19 21,83 0,67 14,63 6,12 133,60 2,19 72,2 Example 20 22,85 0,445 10,17 5,78 132,07 2,10 72,1 Example 21 15,12 0,925 13,99 4,62 69,85 2,05 71,5 Example 22 31,98 0,937 29,97 6,52 208,51 2,12 70,3 Example 23 14,59 0,945 13,79 6,68 97,46 2,01 70,1 Comparative example 1 31,75 0,979 31,08 3,92 124,46 2,53 65,5 Comparative example 2 15,86 0,452 7,17 5,28 83,74 1,93 73,9 Comparative example 3 31,95 0,992 31,69 3,86 123,33 2,59 64,8 Comparative example 4 19,16 0,453 8,68 5,92 113,43 1,89 79,3

[0159] In the batteries manufactured according to the respective embodiments of the present invention, the density was in each case greater than 2.0 g / cm³. 3, wherein the capacity retention rate after 1000 cycles at 25 °C and 1 C was equal to or greater than 70%. It is evident from this that the battery containing the positive electrode sheet according to the invention exhibits both excellent energy density and excellent cycle performance.

[0160] From the comparison of embodiments 1 to 7 with embodiments 8 to 9, embodiments 10 to 12 with embodiments 13 to 17 and embodiments 18 to 19 with embodiment 20, it is evident that if the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet, the roundness R of the ternary positive electrode material and the Dv50 particle size of the lithium manganese iron phosphate agglomerates satisfy the preferred range of the present invention, this is more advantageous for achieving a balance between energy density and cycle performance of the battery.

[0161] From the comparison of embodiments 1 to 7 with embodiments 10 to 12, embodiments 8 to 9 with embodiments 13 to 17 and embodiment 20 with embodiments 21 to 22, it can be seen that the energy density and the cycle performance of the battery are relatively better when the positive electrode 108 ≤ S·d ≤ 158.

[0162] From the comparison of embodiments 1 to 7 with embodiments 18 to 19, embodiments 8-9 with embodiment 20 and embodiments 13 to 17 with embodiments 21 to 22, it can be seen that the energy density and the cycle performance of the battery are relatively better when the positive electrode sheet 16.8 ≤ S·R ≤ 23.2 is satisfied.

[0163] From comparative examples 1 to 4, it can be seen that even if the ratio S of the peak area of ​​the diffraction peak of the (003) crystal plane to the peak area of ​​the diffraction peak of the (102) crystal plane in the XRD spectrum of the positive electrode material with a fully charged positive electrode sheet and the roundness R of the ternary positive electrode material are each in a suitable range, the energy density or the cycle performance of the battery is too poor if the value of S·R exceeds the range of 10 to 30, which means that energy density and cycle performance cannot be balanced.

[0164] Finally, it should be noted that the foregoing embodiments serve only to illustrate the technical solutions herein and are not intended to limit them. Although the present application has been described in detail with reference to preferred embodiments, the person skilled in the art should understand that he or she may modify or equivalently replace the technical solutions of this text without deviating from the nature and scope of the technical solutions herein.

[0165] The present application discloses a positive electrode sheet, a lithium-ion battery, and an electrical device and relates to the field of battery technology. The positive electrode sheet according to the invention comprises a positive current collector and a positive electrode material applied to the positive current collector, wherein the positive electrode material contains a positive active material, the positive active material comprising a lithium-manganese-iron-phosphate agglomerate and a ternary positive electrode material.By controlling a ratio S of a peak area of ​​a diffraction peak of a (003)-crystal plane to a peak area of ​​a diffraction peak of a (102)-crystal plane in an XRD spectrum of the positive electrode material for a fully charged positive electrode sheet and a roundness R of the ternary positive electrode material such that 10 ≤ S·R ≤ 30, the positive electrode sheet has a suitable density, enabling a battery containing this positive electrode sheet to have both good energy density and good cycle performance.

Claims

[1] Positive electrode sheet, characterized by , that it comprises a positive current collector and a positive electrode material applied to the positive current collector, wherein the positive electrode material contains a positive active material, the positive active material comprising a lithium manganese iron phosphate agglomerate and a ternary positive electrode material, wherein the positive electrode sheet satisfies: 0≤S⋅R≤30; where S represents a ratio of a peak area of ​​a diffraction peak of a (003)-crystal plane to a peak area of ​​a diffraction peak of a (102)-crystal plane in an XRD spectrum of the positive electrode material for a fully charged positive electrode sheet, and where R represents the roundness of the ternary positive electrode material. [2] Positive electrode sheet according to claim 1, characterized by , that the positive electrode sheet satisfies: 16.8 ≤ S·R ≤ 23.

2. [3] Positive electrode sheet according to claim 1, characterized by , that S lies in a range of 15 to 32, and / or that R lies in a range of 0.4 to 1. [4] Positive electrode sheet according to claim 3, characterized by that S lies in a range of 20 to 25, and / or that R lies in a range of 0.6 to 0.

98. [5] Positive electrode sheet according to claim 1, characterized by , that the positive electrode sheet further satisfies: 32 ≤ S·d ≤ 320 and / or 2.5µm ≤ d ≤ 10µm; where d represents the Dv50 particle size of the lithium manganese iron phosphate agglomerate and is given in µm. [6] Positive electrode sheet according to claim 5, characterized by , that the positive electrode sheet further satisfies: 108 ≤ S·d ≤ 158 and / or 4.2µm ≤ d ≤ 6.8 µm. [7] Positive electrode sheet according to claim 1, characterized by, that the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary positive electrode material is 1: (0.05 to 20). [8] Positive electrode sheet according to claim 1, characterized by that the ternary positive electrode material is selected from at least one of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide. [9] Lithium-ion battery, characterized by , that it comprises a positive electrode sheet according to one of claims 1 to 8. [10] Electrical device, characterized by that it comprises a lithium-ion battery according to claim 9.

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