Phosphate material as well as preparation method and application thereof

Abstract

The invention provides a phosphate material as well as a preparation method and application thereof. The phosphate material comprises a phosphate material matrix and a first coating layer coating at least part of the surface of the phosphate material matrix, the first coating layer comprises a ternary active material; in the Fourier transform infrared absorption spectrum of the phosphate material, the average red shift amount of the characteristic absorption peak of the phosphate radical group is 8 cm <-1 >-15 cm <-1 >. The phosphate material provided by the invention can improve the energy density and cycle performance of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a phosphate material, its preparation method, and its application. Background Technology

[0002] Phosphate materials, as positive electrode active materials for lithium-ion batteries, are widely used in energy storage systems requiring high safety and long cycle life, such as electric vehicles, power tools, grid energy storage, and consumer electronics. Their olivine-type structure endows the materials with excellent thermal stability and structural reversibility, and the raw material cost is low, making them an important candidate material to replace traditional ternary active materials.

[0003] Existing technologies improve battery energy density and cycle performance by coating ternary active materials onto the surface of phosphate materials. However, the improvement in energy density and cycle performance is limited. Therefore, there is an urgent need to develop a phosphate material that can further enhance battery energy density and cycle performance. Summary of the Invention

[0004] The main objective of this invention is to provide a phosphate material that, when applied to batteries, can improve the energy density and cycle performance of the batteries.

[0005] The present invention also provides a method for preparing phosphate materials, which can prepare the above-mentioned phosphate materials, and the process is simple and low in cost.

[0006] The present invention also provides a positive electrode sheet comprising the above-mentioned phosphate material, and therefore, when this positive electrode sheet is applied to a battery, it can improve the energy density and cycle performance of the battery.

[0007] The present invention also provides a battery comprising the above-described positive electrode, thereby the battery having excellent energy density and cycle performance.

[0008] In a first aspect, the present invention provides a phosphate material, comprising a phosphate material matrix and a first coating layer covering at least a portion of the surface of the phosphate material matrix; the first coating layer comprises a ternary active material;

[0009] In the Fourier transform infrared absorption spectrum of the phosphate material, the average redshift of the characteristic absorption peak of the phosphate group is 8 cm⁻¹. -1 ~15cm -1 .

[0010] As described above, in the X-ray diffraction spectrum of the phosphate material, the diffraction peak corresponding to the (101) crystal plane shifts by 0.01° to 0.1° after 300 cycles at 1C / 3V~4.35V;

[0011] And / or, in the X-ray diffraction spectrum of the phosphate material, the diffraction peak corresponding to the (003) crystal plane shifts by 0.01° to 0.1° before and after 300 cycles at 1C / 3V~4.35V.

[0012] The phosphate material as described above further includes a conductive layer covering at least a portion of the surface of the first coating layer; the conductive layer comprises a conductive material.

[0013] The conductive material in the phosphate material described above includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene, preferably MXene.

[0014] The phosphate material described above has a matrix with a chemical composition of LiMn. x Fe 1-x-y Q y PO4, wherein 0 ≤ x ≤ 0.8, 0 ≤ y ≤ 0.05, and Q includes at least one of Mg, Ti, Zr, Al, Nb, and Cu;

[0015] And / or, the chemical composition of the ternary active material is LiNi a Co b Mn c M 1-a-b-c O2, wherein M includes at least one of Al, Mg, Ti, W, Zr, and Nb, and 0 < a < 1, 0 < b < 1, 0 < c < 1, and 0 < a + b + c ≤ 1.

[0016] In the phosphate material described above, the ratio of the average particle size of the phosphate material matrix to the average particle size of the ternary active material is 4.4 to 16.

[0017] Preferably, the average particle size of the phosphate material matrix is ​​4 μm to 10 μm;

[0018] And / or, the average particle size of the ternary active material is 0.5 μm to 2 μm;

[0019] And / or, the ratio of the thickness of the first coating layer to the thickness of the conductive layer is (2.5~12.5):1;

[0020] Preferably, the thickness of the first coating layer is 1 μm to 3 μm;

[0021] And / or, the thickness of the conductive layer is 0.2 μm to 1 μm.

[0022] The phosphate material described above has a phosphate matrix comprising 88% to 93% of the total mass of the phosphate material.

[0023] And / or, the first coating layer accounts for 5% to 10% of the mass percentage of the phosphate material;

[0024] And / or, the conductive layer accounts for 1% to 3% of the mass percentage of the phosphate material.

[0025] Secondly, the present invention provides a method for preparing the phosphate material as described above, comprising the following steps:

[0026] The surface of the phosphate material matrix is ​​subjected to positive charge loading treatment to obtain a phosphate material precursor with positive charge loaded on the surface;

[0027] The first system, comprising the phosphate material precursor, the ternary active material precursor, and the lithium source, is subjected to a first sintering treatment to obtain the phosphate material.

[0028] The preparation method described above, wherein the positive charge loading treatment on the surface of the phosphate material matrix includes: using a positive charge generating agent to perform a positive charge loading treatment on the surface of the phosphate material matrix to obtain a phosphate material precursor with a positive charge loaded on its surface;

[0029] Preferably, the positive charge generating agent comprises plasma and / or polyethyleneimine;

[0030] And / or, the primary sintering treatment includes: performing a first calcination treatment at 300℃~400℃ for 2h~8h, and a second calcination treatment at 500℃~700℃ for 8h~11h;

[0031] And / or, the molar ratio of the phosphate material precursor to the ternary active material precursor is 1:(0.05~0.1).

[0032] And / or, the first sintering process further includes: performing a second sintering process on a second system comprising the phosphate material and the conductive material to obtain a phosphate material having a first coating layer and a conductive layer;

[0033] Preferably, the temperature of the secondary sintering treatment is 100℃~120℃;

[0034] And / or, the molar ratio of the phosphate material to the conductive material is 1:(0.01~0.03).

[0035] And / or, the conductive material includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene.

[0036] Thirdly, the present invention provides a positive electrode sheet comprising the phosphate material as described above or the phosphate material prepared according to the preparation method described above.

[0037] Fourthly, the present invention provides a battery comprising the positive electrode sheet as described above.

[0038] The phosphate material provided by this invention, by coating a ternary active material on the surface of a phosphate material matrix and defining the characteristic absorption peaks of phosphate groups in the Fourier transform infrared absorption spectrum of the phosphate material, can improve the interfacial bonding force between the phosphate material matrix and the ternary active material, so that when the phosphate material is applied to a battery, the energy density and cycle performance of the battery can be improved. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 Fourier transform infrared absorption spectra of phosphate materials in Example 1 and Comparative Example 1 provided by the present invention;

[0041] Figure 2 X-ray diffraction patterns of the phosphate material before and after cycling in Example 1 of this invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] With the increasing global demand for clean energy and sustainable transportation, lithium-ion batteries, as core energy storage devices, have received widespread attention regarding their performance, safety, and cost. Among numerous cathode active materials, phosphate materials are considered important candidates for next-generation high-performance cathode active materials due to their unique advantages. Specifically, they possess an olivine-type crystal structure, in which strong covalent PO bonds enable them to maintain excellent thermal and structural stability even under full charge, fundamentally overcoming the inherent defects of high-nickel ternary active materials (such as NCM and NCA) in terms of thermal runaway risk. Furthermore, the manganese and iron elements used in phosphate materials are abundant in the Earth's crust, have low raw material costs, and are environmentally friendly. Based on these characteristics, phosphate materials are considered to have broad application prospects in applications requiring high safety and long cycle life, such as electric vehicles, power tools, large-scale grid energy storage, and high-end consumer electronics, making them an ideal choice to replace or partially replace traditional ternary active materials.

[0044] However, despite the significant advantages of phosphate materials in terms of safety and cost, existing phosphate materials still suffer from two core drawbacks in practical battery applications that urgently need to be addressed: insufficient energy density and poor cycle performance. Current technologies attempt to improve battery energy density and cycle performance by coating the surface of phosphate materials with ternary active materials.

[0045] The inventors of this application discovered through research that the lack of a strong interaction interface between phosphate materials and ternary active materials makes them prone to structural separation during cycling, leading to capacity decay and poor battery cycle performance and energy density. Improving the interfacial bonding force between phosphate materials and ternary active materials can thereby improve the battery's energy density and cycle performance.

[0046] Based on this, in a first aspect, the present invention provides a phosphate material, comprising a phosphate material matrix and a first coating layer covering at least a portion of the surface of the phosphate material matrix; the first coating layer comprises a ternary active material; and in the Fourier transform infrared absorption spectrum of the phosphate material, the average redshift of the characteristic absorption peak of the phosphate group is 8 cm⁻¹. -1 ~15cm -1 For example, it can be 8cm -1 9cm -1 10cm -1 11cm -1 12cm -1 13cm -1 14cm -1 15cm -1 or a range consisting of any two of them.

[0047] The phosphate material provided by this invention, by coating a ternary active material onto the surface of a phosphate material matrix and defining the characteristic absorption peak of the phosphate group in the Fourier transform infrared absorption spectrum of the phosphate material, enables the application of this phosphate material in batteries to improve the energy density and cycle performance. This is because the average redshift of the characteristic absorption peak of the phosphate group in the Fourier transform infrared absorption spectrum is 8 cm⁻¹. -1 ~15cm -1 This indicates that electron transfer occurs between the phosphate groups in the phosphate matrix and the ternary active material, thereby inhibiting manganese ion dissolution and forming a strong coupling interface, enhancing the structural stability of the material. This allows the ternary active material coated on the surface of the phosphate matrix to fully exert its function, significantly improving the overall energy density and cycle performance of the battery.

[0048] It should be noted that, keeping other conditions identical, the characteristic absorption peaks of the phosphate groups in the phosphate material exhibit a redshift compared to the uncoated phosphate material in the infrared absorption spectrum. The average redshift represents the average redshift of the three characteristic absorption peaks of the phosphate groups in the infrared absorption spectrum.

[0049] Therefore, the phosphate material provided by the present invention, by coating the surface of the phosphate material matrix with a ternary active material and defining the characteristic absorption peak of the phosphate group in the Fourier transform infrared absorption spectrum of the phosphate material, can improve the interfacial bonding force between the phosphate material matrix and the ternary active material, so that when the phosphate material is applied to the battery, the energy density and cycle performance of the battery can be improved.

[0050] In some embodiments of the present invention, in some examples, the diffraction peak corresponding to the (101) crystal plane in the X-ray diffraction spectrum (XRD) of the phosphate material has a peak position shift of 0.01° to 0.1° before and after 300 cycles at 1C / 3V to 4.35V. For example, it can be a range of 0.01°, 0.02°, 0.03°, 0.04°, 0.05°, 0.06°, 0.07°, 0.08°, 0.09°, 0.1° or any combination thereof.

[0051] In some embodiments, in the X-ray diffraction (XRD) spectrum of the phosphate material, the peak position shift of the diffraction peak corresponding to the (003) crystal plane after 300 cycles at 1C / 3V~4.35V is 0.01°~0.1°, for example, it can be a range of 0.01°, 0.02°, 0.03°, 0.04°, 0.05°, 0.06°, 0.07°, 0.08°, 0.09°, 0.1° or any combination thereof.

[0052] The small peak shift in XRD indicates good material structural stability, no significant interface separation, and good crystal structure and cycle stability. This further allows the ternary active material coated on the phosphate matrix to fully exert its function, significantly improving the overall energy density and cycle performance of the battery.

[0053] In the XRD spectrum, the diffraction peaks corresponding to the (101) crystal plane and the (003) crystal plane shifted in position after 300 cycles at 1C / 3V~4.35V. Here, the cycle refers to: at 25℃ and normal pressure (0.1MPa), phosphate material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone solvent at a mass percentage ratio of 95:3:2 to obtain a positive electrode slurry. The positive electrode slurry was coated on aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet containing a positive electrode active layer with a thickness of 100μm. The negative electrode was graphite, and together with the separator polypropylene and the electrolyte (composed of 1mol / L LiPF6, solvent EC / DMC / DEC=v / v / v:1 / 1 / 1) it formed a full cell. At 25°C, the full battery is charged at a constant current of 1C to 4.35V, then charged at a constant voltage of 4.35V to a current of 0.05C, and then discharged at a discharge rate of 1C to 3V. This charge-discharge cycle is repeated 300 times.

[0054] In some embodiments of the present invention, the phosphate material further includes a conductive layer coating at least a portion of the surface of the first coating layer; the conductive layer comprises a conductive material. The coating with the conductive material can improve the transport efficiency of electrons and lithium ions, thereby reducing interfacial impedance.

[0055] In some embodiments of the present invention, the conductive material includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene, preferably MXene.

[0056] MXene typically refers to two-dimensional transition metal carbides, nitrides, and carbonitrides, with the general chemical formula M. n+1 X n T x “MX” refers to MAX phase materials, and “ene” indicates its graphene-like microlayered structure. The precursor of MXene is a ternary layered carbon / nitride MAX phase material, where “M” represents a transition metal (Sc, Ti, Zr, V, Nb, Mo, Cr, Hf, and Ta, etc.), “A” represents some elements of Group IIIA or IVA (such as Al, Si, P, Ga, Ge, As, etc.), “X” represents C or N, and “T” represents the functional groups or modifiers covering the surface of the MXene material (such as -OH, -O, -F, and -Cl functional groups).

[0057] MXene, through its two-dimensional structure and surface functional groups, forms multi-channel electron transport paths, improving material conductivity and lithium-ion diffusion efficiency, reducing interfacial polarization, and lowering impedance. The two-dimensional sheets of MXene bind to the surface of the ternary active material via van der Waals forces, forming a conductive network. Simultaneously, electron transfer occurs between its surface functional groups and the ternary active material, enhancing interfacial interactions and thereby improving the battery's energy density and cycle performance.

[0058] Carbon nanotubes can not only improve the conductivity of materials and reduce interfacial impedance, but also utilize their mechanical strength to suppress particle cracking during cycling, thereby improving the structural stability of materials and thus enhancing the rate performance and cycle performance of batteries.

[0059] Graphene's high conductivity can significantly improve the rate performance of batteries.

[0060] The electron network of amorphous carbon is uniform and unobstructed, which can balance conductivity and ion transport efficiency.

[0061] Phosphate materials can be tested using a scanning electron microscope to obtain the morphology of the conductive material. When the conductive material has a sheet-like structure, it is identified as graphene; when it has a tubular structure, it is identified as carbon nanotubes; when it has a layered structure, it is identified as MXene; and when it has an amorphous structure, it is identified as amorphous carbon.

[0062] In some embodiments of the present invention, the chemical composition of the phosphate material matrix is ​​LiMn. x Fe 1-x-y Q y PO4, wherein 0 ≤ x ≤ 0.8, for example, can be a range of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or any two thereof; 0 ≤ y ≤ 0.05, for example, can be a range of 0, 0.01, 0.02, 0.03, 0.04, 0.05 or any two thereof; Q includes at least one of Mg, Ti, Zr, Al, Nb, and Cu. This invention optimizes the crystal structure stability of phosphate materials by controlling the ratio of Mn and Fe in the phosphate material matrix.

[0063] In some embodiments, the chemical composition of the ternary active material is LiNi a Co b Mn c M 1-a-b-c O2, wherein M includes at least one of Al, Mg, Ti, W, Zr, and Nb, and 0 < a < 1, 0 < b < 1, 0 < c < 1, and 0 < a + b + c ≤ 1.

[0064] For example, a can be a range consisting of 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99, or any two of them; b can be a range consisting of 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99, or any two of them; c can be a range consisting of 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99, or any two of them; a+b+c can be a range consisting of 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any two of them.

[0065] Al doping in ternary active materials 3+ and / or Mg 2+ The Jahn-Teller effect at Ni sites is suppressed by utilizing the lattice stabilizing effect of doped ions. Al 3+ and / or Mg 2+ Doping can enhance the structural stability of ternary active materials, reduce lattice distortion during cycling, and further improve the stability of phosphate materials, thereby improving the energy density and cycle performance of batteries.

[0066] In some embodiments of the present invention, the ratio of the average particle size of the phosphate material matrix to the average particle size of the ternary active material is 4.4 to 16, for example, it can be a range of 4.4, 5, 6, 7, 8, 9, 10, 12, 15, 16 or any two of them, preferably 8 to 15.

[0067] Preferably, the average particle size of the phosphate material matrix is ​​4μm to 10μm, for example, it can be a range of 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm or any two of these.

[0068] In some embodiments, the average particle size of the ternary active material is 0.5 μm to 2 μm, for example, it can be a range of 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm or any two of these.

[0069] The aforementioned average particle size ensures that small-particle ternary active materials can fill the gaps between large-particle phosphate material matrices, achieving close packing between particles, shortening the lithium-ion diffusion path, reducing material porosity, and increasing compaction density, thereby improving the energy density of the battery.

[0070] In some embodiments, the ratio of the thickness of the first covering layer to the thickness of the conductive layer is (2.5~12.5):1, for example, it can be a range of 2.5:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 12.5:1 or any two of them.

[0071] Preferably, the thickness of the first coating layer is 1 μm to 3 μm, for example, it can be a range of 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, 2.2 μm, 2.5 μm, 2.7 μm, 3 μm or any two of these.

[0072] In some embodiments, the thickness of the conductive layer is 0.2 μm to 1 μm, for example, it can be a range of 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm or any combination thereof.

[0073] The thickness of the first coating layer and the conductive layer can avoid the extension of the lithium-ion diffusion path caused by excessive coating, further improve the compaction density of the phosphate material, and thus improve the energy density of the battery.

[0074] In some embodiments of the present invention, the phosphate material matrix accounts for 88% to 93% of the phosphate material by mass, for example, it can be a range of 88%, 89%, 90%, 91%, 92%, 93% or any two of these.

[0075] In some embodiments, the first coating layer accounts for 5% to 10% of the mass percentage of the phosphate material, for example, it can be a range of 5%, 6%, 7%, 8%, 9%, 10%, or any two of these.

[0076] In some embodiments, the conductive layer accounts for 1% to 3% of the mass percentage of the phosphate material, for example, it can be a range of 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.7%, 3%, or any two of these.

[0077] This invention optimizes the mass ratio of each component and balances their functions, allowing each component to fully exert its role, thereby improving the structural stability and conductivity of phosphate materials, and thus increasing the energy density and cycle performance of the battery while reducing interfacial impedance.

[0078] In some embodiments of the present invention, the phosphate material satisfies Formula 1:

[0079] y=Ax 2 +Bx+C Equation 1,

[0080] Where x is the pH value of the phosphate material; y is the number of cycles of the phosphate material at 1C / 3V-4.35V; where 7≤x≤12, for example, it can be a range of 7, 8, 9, 10, 11, 12 or any two of them; 500≤y≤1200, for example, it can be a range of 500, 700, 1000, 1100, 1200 or any two of them; -112≤A≤-111, for example, it can be -112, - The range consisting of 111.9, -111.7, -111.5, -111.3, -111, or any two of them; 2125≤B≤2130, for example, it can be a range consisting of 2125, 2126, 2127, 2128, 2130, or any two of them; -8910≤C≤-8905, for example, it can be a range consisting of -8910, -8908, -8907, -8906, -8905, or any two of them.

[0081] This invention optimizes the crystallinity and structural stability of phosphate materials by controlling the pH value. A pH of 7-12 ensures sufficient diffusion of lithium ions during sintering and the formation of a stable crystal lattice structure. A moderate increase in pH enhances the structural compactness of the phosphate material while suppressing side reactions, thereby extending cycle life. Formula 1 can predict the number of battery cycles based on the pH value of the phosphate material. Here, the number of cycles refers to the number of cycles at 25°C when the full battery is charged at a constant current rate of 1C to 4.35V, then charged at a constant voltage of 4.35V to a current rate of 0.05C, and then discharged at a discharge rate of 1C to 3V, repeating this charge-discharge cycle, with a capacity retention of 60%.

[0082] In some embodiments, pH can be controlled by adjusting the ratio of lithium source (such as lithium carbonate) to metal source (such as iron phosphate or manganese oxide) to ensure that lithium ions diffuse sufficiently during sintering and form a stable crystal structure.

[0083] When testing the pH value of phosphate materials, 5g of phosphate material can be dissolved in 100g of water to obtain a phosphate material solution, and the pH value of the phosphate material solution can be tested using a pH meter.

[0084] Secondly, the present invention provides a method for preparing the phosphate material as described above, comprising the following steps:

[0085] The surface of the phosphate material matrix is ​​subjected to positive charge loading treatment to obtain a phosphate material precursor with positive charge loaded on the surface;

[0086] A first system consisting of a phosphate material precursor, a ternary active material precursor, and a lithium source is subjected to a sintering process to obtain a phosphate material.

[0087] By applying a positive charge loading treatment to the surface of the phosphate material matrix, the ternary active material precursor is uniformly anchored to its surface using electrostatic adsorption, forming a strongly interacting coupling interface, thus solving the problem of weak interfacial bonding caused by traditional physical mixing.

[0088] A sintering process in the presence of a lithium source can transform the ternary active material precursor anchored on the surface into a ternary active material, resulting in the ternary active material being uniformly and firmly coated on the surface of the phosphate material matrix.

[0089] In one embodiment, the phosphate material matrix can be prepared by a method comprising the following steps:

[0090] Lithium source, iron source, manganese source and phosphorus source are mixed, ball-milled in a high-speed mixer for 3h~5h, and then dried in a forced-air drying oven to obtain phosphate material matrix precursor;

[0091] Under a nitrogen atmosphere, the phosphate material matrix precursor is pre-sintered at 300℃~600℃ for 8h~16h (heating rate 5℃ / min), then sintered at 600℃~800℃ for 10h~15h (heating rate 3.5℃ / min), and finally ball-milled to obtain the phosphate material matrix.

[0092] A carbon source can also be added to the raw materials, so that at least part of the surface of the resulting phosphate material matrix is ​​coated with a carbon coating layer.

[0093] For example, the lithium source can be lithium carbonate and / or lithium phosphate; the iron source can be at least one of ferrous phosphate, ferric oxide, and ferrous oxalate; the manganese source can be manganese carbonate and / or manganese oxide; the phosphorus source can be phosphoric acid and / or ammonium hydrogen phosphate; and the carbon source can be sucrose and / or glucose.

[0094] In some embodiments of the present invention, the positive charge loading treatment of the surface of the phosphate material matrix includes: using a positive charge generating agent to perform a positive charge loading treatment on the surface of the phosphate material matrix to obtain a phosphate material precursor with a positive charge loaded on the surface.

[0095] Preferably, the positive charge generating agent includes plasma and / or polyethyleneimine.

[0096] In one embodiment, the phosphate material matrix is ​​immersed in a polyethyleneimine (PEI) solution (concentration can be 5%-30%) for treatment, thereby loading the surface of the phosphate material matrix with a positive charge. Specifically, the amine groups (-NH2) of PEI undergo a protonation reaction with the phosphate groups on the surface of the phosphate material matrix, imparting a positive charge to the phosphate material matrix and providing conditions for the electrostatic adsorption of the subsequent ternary active material precursor.

[0097] In another embodiment, oxygen-containing functional groups (-COOH, -OH) are introduced onto the surface of the phosphate material matrix through plasma treatment (such as oxygen plasma), enabling electrostatic adsorption of the ternary active material precursor. Plasma treatment can achieve surface charge regulation with low energy consumption, while the oxygen-containing functional groups form strong coordination bonds with the metal sites of the ternary active material, improving the uniformity of the ternary active material coating and thus enhancing the cycle performance of the battery.

[0098] In some embodiments, the primary sintering process includes: performing a first calcination treatment at 300°C to 400°C for 2 hours to 8 hours, and performing a second calcination treatment at 500°C to 700°C for 8 hours to 11 hours.

[0099] For example, the temperature of the first calcination treatment can be a range of 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 300℃, 400℃ or any two of these, and the time can be a range of 2h, 3h, 4h, 5h, 6h, 7h, 8h or any two of these; the temperature of the second calcination treatment can be a range of 500℃, 520℃, 550℃, 570℃, 600℃, 620℃, 650℃, 670℃, 700℃ or any two of these, and the time can be a range of 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h or any two of these.

[0100] By controlling the temperature and time of the first and second calcinations, the ternary precursor crystallizes in situ on the surface of the phosphate material matrix, forming a tightly coupled core-shell structure, thus avoiding interface separation caused by traditional physical mixing. The two-stage calcination process avoids excessive sintering of the ternary active material at high temperatures, preventing particle agglomeration, resulting in a more uniform first coating layer thickness, a more suitable primary particle size, and improved cycle performance.

[0101] In one embodiment, microwave calcination can be used to shorten the calcination time by utilizing the rapid heating characteristics of microwave radiation. Furthermore, microwave calcination can uniformly heat the material, reduce abnormal grain growth, ensure a uniform distribution of the first coating layer, and simultaneously increase the compaction density of the phosphate material.

[0102] In some embodiments, the molar ratio of the phosphate material precursor to the ternary active material precursor is 1:(0.05~0.1), for example, it can be a range of 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.099, 1:0.1, or any two of these. The thickness of the first coating layer can be controlled to avoid over-coating leading to increased impedance.

[0103] In some embodiments, after the first sintering process, the process further includes: performing a second sintering process on a second system comprising a phosphate material and a conductive material to obtain a phosphate material having a first coating layer and a conductive layer.

[0104] Preferably, the temperature of the secondary sintering treatment is 100℃~120℃, for example, it can be a range of 100℃, 102℃, 105℃, 107℃, 110℃, 112℃, 115℃, 117℃, 120℃ or any combination thereof.

[0105] The secondary sintering process can be carried out under vacuum conditions, which allows the conductive layer to be uniformly coated on the surface of the first coating layer, thereby improving the conductivity of the phosphate material and reducing the interfacial impedance.

[0106] This invention can also employ chemical vapor deposition (CVD) to deposit conductive materials on the surface of a phosphate substrate. CVD enables atomically uniform coating of the conductive material, resulting in a more uniform coating thickness, thereby reducing interfacial impedance and improving battery cycle performance.

[0107] In some embodiments, the molar ratio of phosphate material to conductive material is 1:(0.01~0.03), for example, it can be a range of 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.026, 1:0.028, 1:0.03, or any combination thereof. The thickness of the conductive layer can be controlled to avoid over-coating leading to increased impedance.

[0108] In some embodiments, the conductive material includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene. This can further improve the conductivity of the phosphate material and reduce the interfacial impedance.

[0109] In one embodiment, the conductive material includes MXene, which is vacuum sintered in an Ar / H2 mixed atmosphere. The reducing properties of H2 enhance the interfacial bonding between MXene and the ternary active material. The Ar / H2 atmosphere reduces MXene surface oxidation, lowers interfacial impedance, and improves cycle performance.

[0110] In another embodiment, multilayer MXene is used for coating, with each layer of MXene having different functional groups (such as alternating coatings of Ti3C2O and Ti3C2OH). The synergistic effect of different functional groups enhances interfacial electron transfer, forming a denser conductive network and further reducing impedance. At the same time, the difference in functional groups can enhance the interfacial bonding force between MXene and ternary active materials, improving the cycle performance of the battery.

[0111] Thirdly, the present invention provides a positive electrode sheet comprising the phosphate material as described above or the phosphate material prepared according to the preparation method described above.

[0112] The positive electrode sheet of the present invention can be prepared using conventional techniques in the art. Specifically, the above-mentioned phosphate material, conductive agent, and binder can be uniformly dispersed in a solvent to obtain a positive electrode active slurry. Then, the positive electrode active slurry is coated on at least one functional surface of the positive electrode current collector, and after drying, the positive electrode sheet of the present invention can be obtained.

[0113] This invention does not specifically limit the types of conductive agents and adhesives. The conductive agents, adhesives and other components can all be conventional substances in the art. For example, the conductive agent may include one or more of conductive carbon black, carbon nanotubes, conductive graphite and graphene, and the adhesive may include one or more of polyvinylidene fluoride (PVDF), acrylic modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber and styrene-acrylic rubber.

[0114] The present invention does not specifically limit the coating method, and any coating method such as gravure coating, extrusion coating, spraying, screen printing, etc. can be used to achieve the coating of the positive electrode active layer slurry.

[0115] The positive electrode sheet provided by the present invention includes the above-mentioned phosphate material, so the positive electrode sheet has a high compaction density. When applied to a battery, it can improve the energy density and cycle performance of the battery.

[0116] The compaction density of the positive electrode sheet can be 2.8 g / cm³. 3 ~3g / cm 3 For example, it could be 2.8 g / cm³. 3 2.81 g / cm 3 2.82 g / cm 3 2.83 g / cm 3 2.84 g / cm 3 2.85g / cm 3 2.86 g / cm 3 2.87 g / cm 3 2.88g / cm 3 2.89 g / cm 3 3g / cm 3 or a range consisting of any two of them.

[0117] Fourthly, the present invention provides a battery comprising the positive electrode sheet as described above, which has advantages corresponding to the positive electrode sheet described above, and will not be elaborated further.

[0118] In addition to the positive electrode, the battery of the present invention also includes a separator, a negative electrode, and an electrolyte. The composition of the negative electrode can refer to conventional negative electrode sheets in the art, and the separator can also be a separator commonly used in the art, such as a PP film or a PE film.

[0119] The battery of the present invention can be prepared using conventional methods in the art. Specifically, the positive electrode, separator and negative electrode can be stacked in sequence, and the cell can be obtained by stacking or winding. Then, the battery can be obtained by baking, liquid injection, formation and packaging.

[0120] The battery of the present invention can be an all-solid-state battery.

[0121] The battery of the present invention can be a single cell, a battery pack, a battery stack, or a cylindrical cell formed by connecting single cells. These cells can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or a hybrid connection including these connection methods, etc., without particular limitation.

[0122] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0123] Example 1

[0124] The preparation method of the phosphate material in this embodiment includes the following steps:

[0125] 1) Lithium carbonate (lithium source), ferrous phosphate (iron source), manganese carbonate (manganese source), phosphoric acid (phosphorus source), and glucose (carbon source) are mixed to obtain a mixed system. The mixed system is ball-milled in a high-speed mixer for 3 hours. The ball-milled mixture is then dried in a forced-air drying oven to obtain a phosphate material matrix precursor. Among them, glucose accounts for 15 wt% of the mixed system, and the molar ratio of lithium in the lithium source, phosphorus in the phosphorus source, manganese in the manganese source, and iron in the iron source is 1:1:0.6:0.4.

[0126] 2) The phosphate material matrix precursor was pre-sintered at 450℃ for 10 hours under a nitrogen atmosphere with a heating rate of 5℃ / min, and then sintered at 750℃ for 13 hours with a heating rate of 3.5℃ / min. The precursor was then ball-milled at 500 rpm to obtain the phosphate material matrix. The phosphate material matrix includes a core of LiFe. 0.4 Mn 0.6 PO4 and a carbon coating layer present on the surface of the core.

[0127] 3) The phosphate material matrix obtained in step 2) is placed in 20% polyethyleneimine (PEI) for positive charge loading treatment. After drying, a phosphate material precursor with a positively charged surface is obtained. The phosphate material precursor and the ternary active material precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2 is mixed evenly at a molar ratio of 1:0.08, so that the ternary active material precursor is loaded on the surface of the phosphate material precursor.

[0128] 4) The phosphate material precursor loaded with ternary active material precursor obtained in step 3) and the lithium source are mixed evenly at a molar ratio of 1:1.05. The mixture is then subjected to a first calcination treatment at 350°C at 2°C / min for 2 hours, and then subjected to a second calcination treatment at 650°C at 2°C / min for 9.5 hours to obtain the phosphate material with the first coating layer.

[0129] 5) The phosphate material with the first coating layer obtained in step 4) is mixed with MXene (Ti3C2T2, where T includes -O, -OH, and -F) at a molar ratio of 1:0.02 and subjected to a secondary sintering treatment at 110°C under vacuum for 6 hours to obtain a phosphate material with the first coating layer and a conductive layer.

[0130] Phosphate materials include phosphate material matrices (LiFe) 0.4 Mn 0.6 PO4), a first coating layer covering at least a portion of the surface of a phosphate material matrix, and a conductive layer covering at least a portion of the surface of the first coating layer, wherein the first coating layer includes a ternary active material (LiNi). 0.8 Co 0.1 Mn 0.1 O2), the conductive layer includes MXene (Ti3C2T2, where T includes -O, -OH, -F).

[0131] Example 2

[0132] The preparation method of the phosphate material in Example 2 is basically the same as that in Example 1, except that the second calcination treatment time is 9 hours.

[0133] Example 3

[0134] The preparation method of the phosphate material in Example 3 is basically the same as that in Example 1, except that the second calcination treatment time is 10 hours.

[0135] Example 4

[0136] The preparation method of the phosphate material in Example 4 is basically the same as that in Example 1, except that the second calcination treatment time is 8.5 hours.

[0137] Example 5

[0138] The preparation method of the phosphate material in Example 5 is basically the same as that in Example 1, except that the temperature of the first calcination treatment is 400°C.

[0139] Example 6

[0140] The preparation method of the phosphate material in Example 6 is basically the same as that in Example 1, except that the temperature of the first calcination treatment is 300°C.

[0141] Example 7

[0142] The preparation method of the phosphate material in Example 7 is basically the same as that in Example 1, except that the temperature of the second calcination treatment is 700°C.

[0143] Example 8

[0144] The preparation method of the phosphate material in Example 8 is basically the same as that in Example 1, except that the temperature of the second calcination treatment is 500°C.

[0145] Example 9

[0146] The preparation method of the phosphate material in Example 9 is basically the same as that in Example 1, except that the second calcination treatment time is 8 hours.

[0147] Example 10

[0148] The preparation method of the phosphate material in Example 10 is basically the same as that in Example 1, except that the second calcination treatment time is 11 hours.

[0149] Example 11

[0150] The preparation method of the phosphate material in Example 11 is basically the same as that in Example 1, except that the temperature of the second calcination treatment is 700°C and the time is 11h.

[0151] Example 12

[0152] The preparation method of the phosphate material in Example 12 is basically the same as that in Example 1, except that the temperature of the second calcination treatment is 500°C and the time is 8 hours.

[0153] Example 13

[0154] The preparation method of the phosphate material in Example 13 is basically the same as that in Example 1, except that the molar ratio of the phosphate material precursor to the ternary active material precursor is 1:0.05.

[0155] Example 14

[0156] The preparation method of the phosphate material in Example 14 is basically the same as that in Example 1, except that the phosphate material precursor and the ternary active material precursor are prepared in a molar ratio of 1:0.1.

[0157] Example 15

[0158] The preparation method of the phosphate material in Example 15 is basically the same as that in Example 1, except that the molar ratio of the phosphate material with the first coating layer to MXene (Ti3C2T2, where T includes -O, -OH, and -F) is 1:0.01.

[0159] Example 16

[0160] The preparation method of the phosphate material in Example 16 is basically the same as that in Example 1, except that the phosphate material with the first coating layer and MXene (Ti3C2T2, where T includes -O, -OH, and -F) are prepared in a molar ratio of 1:0.03.

[0161] Example 17

[0162] The preparation method of the phosphate material in Example 17 is basically the same as that in Example 1, except that in step 1), lithium carbonate (lithium source), ferrous phosphate (iron source), manganese carbonate (manganese source), phosphoric acid (phosphorus source), glucose (carbon source), and aluminum hydroxide (doping source) are mixed to obtain a mixed system. The mixed system is ball-milled in a high-speed mixer for 3 hours, and the ball-milled mixture is dried in a forced-air drying oven to obtain the phosphate material matrix precursor. Glucose accounts for 15 wt% of the mixed system, and the molar ratio of lithium in the lithium source, phosphorus in the phosphorus source, manganese in the manganese source, iron in the iron source, and aluminum in the doping source is 1:1:0.58:0.4:0.02. Finally, a phosphate material matrix is ​​obtained, which includes a core LiFe... 0.4 Mn 0.58 Al 0.02 PO4 and a carbon coating layer present on the surface of the core.

[0163] Example 18

[0164] The preparation method of the phosphate material in Example 18 is basically the same as that in Example 1, except that in step 1), lithium carbonate (lithium source), ferrous phosphate (iron source), phosphoric acid (phosphorus source), glucose (carbon source), and zirconium oxide (doping source) are mixed to obtain a mixed system. The mixed system is then ball-milled in a high-speed mixer for 3 hours. The ball-milled mixture is then dried in a forced-air drying oven to obtain the phosphate material matrix precursor. Glucose accounts for 15 wt% of the mixed system, and the molar ratio of lithium in the lithium source, phosphorus in the phosphorus source, iron in the iron source, and zirconium in the doping source is 1:1:0.98:0.02. Finally, a phosphate material matrix is ​​obtained, which includes a core LiFe... 0.98 Zr 0.02 PO4 and a carbon coating layer present on the surface of the core.

[0165] Example 19

[0166] The preparation method of the phosphate material in Example 19 is basically the same as that in Example 1, except that step 5 is omitted, that is, no secondary coating is performed, and the surface of the phosphate material is only coated with ternary active material.

[0167] Example 20

[0168] The preparation method of the phosphate material in Example 20 is basically the same as that in Example 1, except that carbon nanotubes are used as the conductive material for the conductive layer.

[0169] Comparative Example 1

[0170] The preparation methods of the phosphate materials in Comparative Example 1 and Example 1 are basically the same, except that steps 3)-5) are omitted, that is, no coating is performed, and the phosphate material matrix is ​​used as the phosphate material.

[0171] Comparative Example 2

[0172] The preparation method of the phosphate material in Comparative Example 2 is basically the same as that in Example 1, except that steps 3)-4) are omitted, that is, no coating is performed, and the surface of the phosphate material is only coated with MXene.

[0173] Comparative Example 3

[0174] The preparation method of the phosphate material in Comparative Example 3 is basically the same as that in Example 1, except that step 3 is omitted, that is, PEI is not used for positive charge loading treatment.

[0175] Experimental example:

[0176] 1. Scanning electron microscopy (SEM) was used to test the morphology of the phosphate material to obtain the conductive material. When the conductive material has a sheet-like structure, it is identified as graphene; when it has a tubular structure, it is identified as carbon nanotubes; when it has a layered structure, it is identified as MXene; and when it has an amorphous structure, it is identified as amorphous carbon.

[0177] 2. Proportion of each component: The content of each element was tested by inductively coupled plasma ICP-AES.

[0178] 3. Average particle size of phosphate matrix and ternary active material: The size of 20 particles of phosphate matrix and ternary active material were measured by scanning electron microscopy (SEM), and the average value was taken to obtain the average particle size of phosphate matrix and ternary active material respectively.

[0179] 4. XRD: The XRD pattern of the phosphate material was obtained by X-ray diffraction. The diffraction peaks corresponding to the (003) crystal plane can represent the layered phase of the ternary active material, and the diffraction peaks corresponding to the (101) crystal plane can represent the phase of the phosphate material. The content of each phase was determined by combining ICP, so as to determine that the ternary active material was coated on the surface of the phosphate material.

[0180] 5. Coating thickness: The coating thickness is obtained by X-ray photoelectron spectroscopy (XPS) etching.

[0181] 6. Fourier Transform Infrared Absorption Spectroscopy (FT-IR): The red shift of phosphate groups in phosphate materials is measured using a Fourier Transform Infrared Absorption Spectrometer, and the average value is taken to obtain the average red shift.

[0182] 7. Compacted density: The thickness of the positive electrode sheet is measured after rolling. The compacted density is calculated based on the surface density, i.e., compacted density = surface density / thickness.

[0183] 8. Cyclic performance: At 25°C and normal pressure (0.1MPa), the phosphate materials, conductive carbon black, and binder polyvinylidene fluoride (PVDF) of each embodiment and comparative example were thoroughly mixed in N-methylpyrrolidone solvent at a mass percentage ratio of 95:3:2 to obtain a positive electrode slurry. The positive electrode slurry was coated on aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet containing a positive electrode active layer with a thickness of 100μm. The negative electrode was graphite, and a full cell was formed with a polypropylene separator and an electrolyte (composed of 1mol / L LiPF6, solvent EC / DMC / DEC=v / v / v:1 / 1 / 1).

[0184] At 25°C, the full battery was charged at a constant current rate of 1C to 4.35V, then charged at a constant voltage of 4.35V to a current rate of 0.05C, and then discharged at a discharge rate of 1C to 3V. This charge-discharge cycle was repeated 300 times. The discharge capacity Q1 at the first cycle and the discharge capacity Q at the 300th cycle were measured. 300 The capacity retention rate after 300 cycles is Q = Q 300 / Q1×100%.

[0185] 9. Impedance: The impedance of the full cell was tested using a Princeton impedance meter.

[0186] 10. Energy Density Test: The full battery was charged at 25℃ with a constant current rate of 0.1C to a voltage of 4.35V, then charged at a constant voltage of 4.35V until the current equals 0.05C. After resting for 5 minutes, it was discharged at a constant current rate of 0.1C to a voltage of 3V. The initial discharge capacity Q of the battery was recorded. 放 and the first discharge energy E 放Weigh the battery and record the mass as W. Calculate the mass energy density ED = E. 放 / W.

[0187] Figure 1 Fourier transform infrared absorption spectra of the phosphate materials of Example 1 and Comparative Example 1 provided by the present invention.

[0188] from Figure 1 As can be seen, in the phosphate material of Example 1, the characteristic absorption peak of the phosphate group has red-shifted compared with that of Comparative Example 1.

[0189] Figure 2 The X-ray diffraction (XRD) spectra of the phosphate material before and after cycling in Example 1 of this invention.

[0190] from Figure 2 As can be seen, the XRD pattern contains the (101) characteristic peak of the phosphate material matrix at 20°~21° and the (003) characteristic peak of the ternary active material at 18°~20°. The peak positions correspond well before and after charge-discharge cycles, and the peak position shift range is 0.01°~0.1°, indicating that the phosphate material has good structural stability and reversibility before and after cycles.

[0191] Table 1

[0192]

[0193] Table 2

[0194]

[0195] As shown in Table 1, compared with the comparative example, the phosphate material provided by the present invention, by coating the ternary active material on the surface of the phosphate material matrix and limiting the characteristic absorption peak of the phosphate group in the Fourier transform infrared absorption spectrum of the phosphate material, can improve the interfacial bonding force between the phosphate material matrix and the ternary active material, so that the phosphate material can improve the energy density and cycle performance of the battery when applied to the battery.

[0196] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A phosphate material, characterized in that, It includes a phosphate material matrix and a first coating layer covering at least a portion of the surface of the phosphate material matrix; the first coating layer includes a ternary active material; In the Fourier transform infrared absorption spectrum of the phosphate material, the average redshift of the characteristic absorption peak of the phosphate group is 8 cm⁻¹. -1 ~15cm -1 .

2. The phosphate material according to claim 1, characterized in that, In the X-ray diffraction spectrum of the phosphate material, the diffraction peak corresponding to the (101) crystal plane shifts by 0.01° to 0.1° after 300 cycles at 1C / 3V~4.35V. And / or, in the X-ray diffraction spectrum of the phosphate material, the diffraction peak corresponding to the (003) crystal plane shifts by 0.01° to 0.1° before and after 300 cycles at 1C / 3V~4.35V.

3. The phosphate material according to claim 1 or 2, characterized in that, The phosphate material further includes a conductive layer covering at least a portion of the surface of the first coating layer; the conductive layer comprises a conductive material.

4. The phosphate material according to claim 3, characterized in that, The conductive material includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene, preferably MXene.

5. The phosphate material according to claim 3 or 4, characterized in that, The chemical composition of the phosphate material matrix is ​​LiMn. x Fe 1-x-y Q y PO4, wherein 0 ≤ x ≤ 0.8, 0 ≤ y ≤ 0.05, and Q includes at least one of Mg, Ti, Zr, Al, Nb, and Cu; And / or, the chemical composition of the ternary active material is LiNi a Co b Mn c M 1-a-b-c O2, wherein M includes at least one of Al, Mg, Ti, W, Zr, and Nb, and 0 < a < 1, 0 < b < 1, 0 < c < 1, and 0 < a + b + c ≤ 1.

6. The phosphate material according to any one of claims 3-5, characterized in that, The ratio of the average particle size of the phosphate material matrix to the average particle size of the ternary active material is 4.4~16; Preferably, the average particle size of the phosphate material matrix is ​​4 μm to 10 μm; And / or, the average particle size of the ternary active material is 0.5 μm to 2 μm; And / or, the ratio of the thickness of the first coating layer to the thickness of the conductive layer is (2.5~12.5):1; Preferably, the thickness of the first coating layer is 1 μm to 3 μm; And / or, the thickness of the conductive layer is 0.2 μm to 1 μm.

7. The phosphate material according to any one of claims 3-6, characterized in that, The phosphate material matrix accounts for 88% to 93% of the mass percentage of the phosphate material; And / or, the first coating layer accounts for 5% to 10% of the mass percentage of the phosphate material; And / or, the conductive layer accounts for 1% to 3% of the mass percentage of the phosphate material.

8. A method for preparing a phosphate material as described in any one of claims 1-7, characterized in that, Includes the following steps: The surface of the phosphate material matrix is ​​subjected to positive charge loading treatment to obtain a phosphate material precursor with positive charge loaded on the surface; The first system, comprising the phosphate material precursor, the ternary active material precursor, and the lithium source, is subjected to a first sintering treatment to obtain the phosphate material.

9. The preparation method according to claim 8, characterized in that, The positive charge loading treatment on the surface of the phosphate material matrix includes: using a positive charge generating agent to perform a positive charge loading treatment on the surface of the phosphate material matrix to obtain a phosphate material precursor with a positive charge loaded on the surface; Preferably, the positive charge generating agent comprises plasma and / or polyethyleneimine; And / or, the primary sintering treatment includes: performing a first calcination treatment at 300℃~400℃ for 2h~8h, and a second calcination treatment at 500℃~700℃ for 8h~11h; And / or, the molar ratio of the phosphate material precursor to the ternary active material precursor is 1:(0.05~0.1). And / or, the first sintering process further includes: performing a second sintering process on a second system comprising the phosphate material and the conductive material to obtain a phosphate material having a first coating layer and a conductive layer; Preferably, the temperature of the secondary sintering treatment is 100℃~120℃; And / or, the molar ratio of the phosphate material to the conductive material is 1:(0.01~0.03). And / or, the conductive material includes at least one of amorphous carbon, graphene, carbon nanotubes, and MXene.

10. A positive electrode plate, characterized in that, This includes the phosphate material according to any one of claims 1-7 or the phosphate material prepared according to the preparation method of claim 8 or 9.

11. A battery, characterized in that, Includes the positive electrode sheet as described in claim 10.

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