Positive electrode material, and preparation method therefor and use thereof

Abstract

A positive electrode material, and a preparation method therefor and the use thereof. The positive electrode material comprises an inner core and a coating layer coating the surface of the inner core, wherein the coating layer is in a crystalline phase-amorphous phase composite state, the amorphous phase is distributed on the outer surface of the positive electrode material, and the lattice parameter c / a of the positive electrode material is 4.935-4.950; and the chemical formula of the inner core is LiyNixCozMndAeDmO2, where 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e＜0.1, and 0.01≤m＜0.1, A is selected from at least one of Mg, Al, Ca and B, and D is selected from at least one of Ti, Ce, Ta, Mo and Zr, and the surface layer in the inner core is an X-rich layer, with X being selected from at least one of P, S, Si, B, Al, Mg, Mo, Zr and Nb. The crystalline phase is a lithium-salt-type polyanionic compound, and the amorphous phase is Li-M1-M2-O, where M1 is selected from at least one of P and S, and M2 is selected from at least one of Al, Mg, Mo, Zr and Nb. The positive electrode material is used in a sulfide solid-state battery, and can significantly improve the high-temperature cycling stability of the sulfide solid-state battery.

Description

Cathode material, preparation method and application thereof

[0001] The present application claims priority to the Chinese patent application No. 202410843447.9, filed on June 26, 2024, and entitled "Cathode material, preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of solid-state batteries, in particular to a cathode material, a preparation method and application thereof. BACKGROUND

[0003] Compared with traditional liquid batteries, solid-state batteries avoid the safety hazards caused by flammable and explosive liquid electrolytes, and can directly use metal lithium as the negative electrode of the battery, greatly reducing the amount of negative electrode material and greatly improving the energy density of the battery. Therefore, solid-state batteries are the key to achieving high safety and high energy density of batteries.

[0004] However, due to the electrochemical potential difference between the oxide cathode and the sulfide electrolyte, the space charge layer effect and the interface side reaction are easily caused, especially in a high-temperature environment, which will further aggravate the occurrence of the interface side reaction, thereby causing the attenuation of the high-temperature cycle capacity, which is not conducive to improving the high-temperature cycle performance of the sulfide all-solid-state battery. SUMMARY

[0005] Therefore, it is necessary to provide a cathode material, a preparation method and application thereof for effectively inhibiting the interface side reaction and significantly improving the high-temperature cycle stability in the sulfide all-solid-state battery.

[0006] A cathode material, comprising a core and a coating layer coated on the surface of the core, the coating layer is in a composite state of crystal phase-amorphous phase, and the amorphous phase is distributed on the outer surface of the cathode material, and the lattice parameter c / a of the cathode material is 4.935-4.950.

[0007] The chemical formula of the core is Li y Ni x Co z Mn d A e D m O2, wherein 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1, A is selected from at least one of Mg, Al, Ca, B, D is selected from at least one of Ti, Ce, Ta, Mo, Zr, and the surface layer of the core is a X-rich layer, X is selected from at least one of P, S, Si, B, Al, Mg, Mo, Zr, Nb.

[0008] In the coating layer, the crystalline phase material is a lithium salt polyanion compound, and the amorphous phase material is Li-M1-M2-O, wherein M1 is at least one selected from P and S, and M2 is at least one selected from Al, Mg, Mo, Zr and Nb.

[0009] In one embodiment, c / a is 4.94-4.95; and / or,

[0010] 1≤y≤1.02, 0.8≤x≤0.95, 0.05≤z≤0.2, 0.01≤d≤0.2, 0.01≤e<0.05, 0.01≤m<0.05, A is at least one selected from Mg, Al and B, D is at least one selected from Ti, Ta and Zr, and X is at least one selected from P, S, Si, Al, Mg and Zr.

[0011] In one embodiment, in the amorphous phase, the molar ratio of Li to M1 and M2 is (0.5-1.5):(0.5-1):(0.05-0.1).

[0012] In one embodiment, in the amorphous phase, the molar ratio of Li to M1 and M2 is (1-1.5):(0.5-0.7):(0.05-0.08).

[0013] In one embodiment, the lithium salt polyanion compound is at least one selected from Li3PO4, Li2HPO4, LiH2PO4, Li2SO4, Li2SO3, Li2SiO3 and Li3BO3.

[0014] In one embodiment, the lithium salt polyanion compound is at least one selected from Li3PO4, Li2SO4 and Li2SiO3.

[0015] In one embodiment, the mass of the amorphous phase is 0.1‰-5‰ of the inner core;

[0016] And / or, the mass of the non-oxygen element of the polyanion in the lithium salt polyanion compound is 0.2‰-2‰ of the inner core.

[0017] In one embodiment, the mass of the amorphous phase is 1‰-4‰ of the inner core;

[0018] And / or, the mass of the non-oxygen element of the polyanion in the lithium salt polyanion compound is 0.5‰-1.5‰ of the inner core.

[0019] In one embodiment, the crystal phase is in island structure, the island structure covers at least part of the surface of the inner core, and the average fluctuation thickness of the island structure is 1-20 nm;

[0020] In one embodiment, the amorphous phase is distributed on the outer surface of the positive electrode material, and the average thickness of the amorphous phase is 1-20 nm;

[0021] In one embodiment, the thickness ratio of the crystal phase to the amorphous phase is 0.5:1-1.2:1;

[0022] In one embodiment, the average thickness of the coating layer is 1-20 nm;

[0023] In one embodiment, the ratio of the thickness of the X-rich layer to the radius of the inner core is 0.05:1-0.5:1.

[0024] In one embodiment, the average fluctuation thickness of the island structure is 1-15 nm;

[0025] In one embodiment, the average thickness of the amorphous phase is 1-15 nm;

[0026] In one embodiment, the thickness ratio of the crystal phase to the amorphous phase is 0.8:1-1.1:1;

[0027] In one embodiment, the average thickness of the coating layer is 1-15 nm;

[0028] In one embodiment, the ratio of the thickness of the X-rich layer to the radius of the inner core is 0.1:1-0.3:1.

[0029] In one embodiment, the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak in the X-ray diffraction pattern of the positive electrode material is 1.70-2.40.

[0030] In one embodiment, the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak is 1.90-2.40.

[0031] A preparation method of the positive electrode material as described above, comprising the following steps:

[0032] A hydroxide precursor containing doping elements A and D is prepared by a coprecipitation reaction, the hydroxide precursor is mixed with a first lithium source, and a first material is prepared by performing a first sintering in an oxygen-containing gas, the chemical formula of the first material is Li y Ni x Co z Mn d A e D mO2, 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1;

[0033] mixing the first material with a polyanion compound, performing a second sintering in an oxygen-containing gas to obtain a second material, wherein the temperature of the second sintering is greater than or equal to 550℃;

[0034] mixing the second lithium source with a salt containing M1 and an oxide containing M2, performing a third sintering in an oxygen-containing gas to obtain the material of amorphous phase;

[0035] mixing the second material with the material of amorphous phase, performing a fourth sintering in an oxygen-containing gas to obtain the positive electrode material, wherein the temperature of the fourth sintering is greater than or equal to 400℃, and the temperature of the second sintering is greater than or equal to the temperature of the fourth sintering.

[0036] In one of the embodiments, the co-precipitation reaction comprises adding a mixed salt solution and a precipitant into water, and performing a reaction in a protective gas to obtain a hydroxide precursor, wherein the molar concentration of the mixed salt in the mixed salt solution is 1mol / L-3mol / L, the molar concentration of the precipitant in water is 5mol / L-10mol / L, and the flow rate of the protective gas is 2L / min-5L / min.

[0037] In one of the embodiments, the molar concentration of the mixed salt in the mixed salt solution is 1mol / L-2mol / L, the molar concentration of the precipitant in water is 5mol / L-8mol / L, and the flow rate of the protective gas is 3L / min-5L / min.

[0038] In one of the embodiments, the polyanion compound is selected from at least one of lithium salt polyanion compounds, ammonium dihydrogen phosphate, and silicic acid;

[0039] and / or, the mass of the polyanion compound is 1‰-7‰ of the first material;

[0040] and / or, the mass of the material of amorphous phase is 0.1‰-5‰ of the second material;

[0041] and / or, the molar ratio of Li in the second lithium source to M1 in the salt containing M1 and M2 in the oxide containing M2 is (0.5-1.5):(0.5-1):(0.05-0.1).

[0042] In one of the embodiments, the temperature of the first sintering is 800℃-1000℃, and the time is 10h-20h;

[0043] and / or, the temperature of the second sintering is 550-800°C, and the time is 5-10h;

[0044] and / or, the temperature of the third sintering is 900-1200°C, and the time is 4-10h;

[0045] and / or, the temperature of the fourth sintering is 400-700°C, and the time is 5-10h.

[0046] In one of the embodiments, the temperature of the first sintering is 800-900°C, and the time is 12-18h;

[0047] and / or, the temperature of the second sintering is 650-800°C, and the time is 8-10h;

[0048] and / or, the temperature of the third sintering is 1000-1200°C, and the time is 8-10h;

[0049] and / or, the temperature of the fourth sintering is 550-700°C, and the time is 8-10h.

[0050] A positive electrode sheet comprising the positive electrode material as described above.

[0051] A sulfide solid-state battery comprising the positive electrode sheet as described above.

[0052] The positive electrode material described in the present application has a unique core-shell structure and lattice parameters. On the one hand, the inner core contains low-valence doping element A and high-valence doping element D, which not only inhibits ion mixing and is conducive to improving capacity and initial coulombic efficiency, but also inhibits interface side reactions and improves phase change reversibility. Meanwhile, the surface layer of the inner core is a X-rich layer, which can also improve bulk stability. On the other hand, the surface of the inner core is a uniform and continuous coating layer. Through the synergistic effect of the crystalline phase and amorphous phase in the coating layer, the coating layer not only has a CEI film-like effect, which can effectively inhibit the interface side reactions between the sulfide electrolyte and the positive electrode, but also the polyanion and part of the non-oxygen elements in the coating layer can form strong covalent bonds with the oxygen atoms in the lattice structure of the inner core, which can inhibit the collapse of the lattice structure caused by deoxidation of the inner core. Meanwhile, the coating layer also has mechanical toughness, which can prevent the particles from cracking due to the drastic change of the lattice constant during the cycle process, thereby ensuring the high-temperature cycle stability.

[0053] Therefore, the use of the positive electrode material described in the present application in a sulfide solid-state battery can significantly improve the capacity, initial coulombic efficiency and high-temperature cycle stability of the sulfide solid-state battery. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0055] FIG. 1 is a scanning electron microscope (SEM) comparison diagram of the positive electrode material prepared in Example 1 and Comparative Example 1, wherein a is the SEM diagram of the positive electrode material prepared in Example 1, and b is the SEM diagram of the positive electrode material prepared in Comparative Example 1;

[0056] FIG. 2 is an energy dispersive spectroscopy (EDS) diagram of the positive electrode material prepared in Example 1, wherein a is the image of the positive electrode material to be tested, and b is the mapping distribution image of phosphorus element;

[0057] FIG. 3 is a transmission electron microscope (TEM) diagram of the surface of the positive electrode material prepared in Example 1;

[0058] FIG. 4 is an X-ray diffraction (XRD) comparison diagram of the positive electrode material prepared in Example 1 and Comparative Example 1, wherein a is the X-ray diffraction spectrum of the positive electrode material prepared in Example 1, b is the X-ray diffraction spectrum of the positive electrode material prepared in Comparative Example 1, and c is the standard X-ray diffraction spectrum (PDF #74-0919) of lithium nickelate;

[0059] FIG. 5 is a sectional view of the positive electrode material prepared in Example 1;

[0060] FIG. 6 is a charge / voltage (dQ / dV) curve comparison diagram of the solid-state battery prepared in Example 1 and Comparative Example 1, wherein a is the dQ / dV curve of the solid-state battery prepared in Example 1, and b is the dQ / dV curve of the solid-state battery prepared in Comparative Example 1;

[0061] FIG. 7 is a charge / discharge curve comparison diagram of the solid-state battery prepared in Example 1 and Comparative Example 1, wherein a is the charge / discharge curve of the solid-state battery prepared in Example 1, and b is the charge / discharge curve of the solid-state battery prepared in Comparative Example 1;

[0062] FIG. 8 is a high-temperature cycle curve comparison diagram of the solid-state battery prepared in Example 1 and Comparative Example 1, wherein a is the high-temperature cycle curve of the solid-state battery prepared in Example 1, and b is the high-temperature cycle curve of the solid-state battery prepared in Comparative Example 1. DETAILED DESCRIPTION

[0063] For the purposes of promoting an understanding of the principles of the application, the application will now be described in more detail below. It will be appreciated, however, that the application can be practiced in many different forms and should not be considered limited to the embodiments or examples set forth herein. Rather, these embodiments or examples are provided so that this disclosure will convey the principles and subtends of the application to those skilled in the art.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the application.

[0065] The application provides a positive electrode material, comprising a core and a coating layer coated on the surface of the core, the coating layer is in a composite state of crystal phase-amorphous phase, and the amorphous phase is distributed on the outer surface of the positive electrode material, and the lattice parameter c / a of the positive electrode material is 4.935-4.950.

[0066] The chemical formula of the core is Li y Ni x Co z Mn d A e D m O2, wherein 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1, A is selected from at least one of Mg, Al, Ca, B, D is selected from at least one of Ti, Ce, Ta, Mo, Zr, and the surface layer of the core is an X-rich layer, X is selected from at least one of P, S, Si, B, Al, Mg, Mo, Zr, Nb.

[0067] In the coating layer, the material of the crystal phase is a lithium salt polyanion compound, and the material of the amorphous phase is Li-M1-M2-O, wherein M1 is selected from at least one of P and S, and M2 is selected from at least one of Al, Mg, Mo, Zr, and Nb.

[0068] The positive electrode material has a unique core-shell structure and lattice parameter. On the one hand, the core contains low-valence doping elements A and high-valence doping elements D, wherein the low-valence element A is easy to be doped into the core lattice structure, which is beneficial to stabilize the lattice structure and inhibit ion mixing, thereby improving the capacity and the first coulombic efficiency; the high-valence element B tends to be pinned on the grain boundary surface, which is beneficial to inhibit the interface side reaction and improve the phase change reversibility; at the same time, the surface layer of the core is an X-rich layer, which is beneficial to improve the structural stability and inhibit the high-temperature interface side reaction.

[0069] On the other hand, the inner core surface is a uniform continuous coating layer, through the synergistic effect of the crystalline phase and amorphous phase in the coating layer, not only does the coating layer have a CEI film-like effect, and the P, S and sulfide electrolyte in the coating layer have good compatibility, which can effectively inhibit the interface side reaction of the sulfide electrolyte and the positive electrode, and the polyanion and part of the non-oxygen elements in the coating layer can form a strong covalent bond with the oxygen atoms in the lattice structure of the inner core, which can inhibit the lattice structure collapse caused by deoxidation of the inner core, and the coating layer also has mechanical toughness, which can prevent the particle cracking caused by the drastic change of the lattice constant during the cycle, thereby ensuring the high-temperature cycle stability.

[0070] It can be understood that c / a is the ratio of the lattice parameter c to the lattice parameter a, due to the doping elements entering the layered structure of the inner core, the lattice parameter c / a of the positive electrode material is increased, when the lattice parameter c / a is 4.935-4.950, the structure stability of the positive electrode material is excellent, as preferred, the lattice parameter c / a of the positive electrode material includes but is not limited to any one value or a range value between any two of 4.935, 4.94, 4.945, 4.95, preferably 4.94-4.95.

[0071] As preferred, in the chemical formula of the inner core, 1≤y≤1.02, 0.8≤x≤0.95, 0.05≤z≤0.2, 0.01≤d≤0.2, 0.01≤e<0.05, 0.01≤m<0.05, A is selected from at least one of Mg, Al, B, D is selected from at least one of Ti, Ta, Zr; X is selected from at least one of P, S, Si, Al, Mg, Zr.

[0072] In an embodiment, the ratio of the thickness of the X-rich layer to the radius of the inner core is 0.05:1-0.5:1, preferably 0.1:1-0.3:1.

[0073] In an embodiment, in the amorphous phase, the molar ratio of Li to M1 and M2 is (0.5-1.5):(0.5-1):(0.05-0.1), preferably (1-1.5):(0.5-0.7):(0.05-0.08), by adjusting the element ratio in the amorphous phase, it is beneficial to optimize the element content of the coating layer, thereby inhibiting the interface side reaction.

[0074] In an embodiment, the lithium salt polyanion compound is selected from at least one of Li3PO4, Li2HPO4, LiH2PO4, Li2SO4, Li2SO3, Li2SiO3, Li3BO3, preferably Li3PO4, Li2SO4, Li2SiO3, which is advantageous to further improve the mechanical toughness of the coating layer, inhibit the generation of cracks in the positive electrode material at high voltage, and the strong covalent bond formed by the polyanion can inhibit the lattice structure collapse caused by deoxidation of the material, thereby further ensuring the high-temperature cycle stability.

[0075] In an embodiment, the mass fraction of the non-oxygen element of the polyanion in the lithium salt polyanion compound is 0.2‰-2‰ of the core, preferably 0.5‰-1.5‰, by adjusting the mass of the non-oxygen element of the polyanion in the lithium salt polyanion compound, which is advantageous to optimize the thickness of the coating layer, thereby obtaining higher ionic conductivity.

[0076] In an embodiment, the crystal phase is in an island structure, the island structure is coated on at least part of the surface of the core, and the average fluctuation thickness of the island structure is 1 nm-20 nm, preferably 1 nm-15 nm, by adjusting the thickness of the crystal phase, which is advantageous to obtain higher ionic conductivity, thereby improving the capacity performance of the battery.

[0077] In an embodiment, the mass fraction of the amorphous phase is 0.1‰-5‰, preferably 1‰-4‰, of the core, by adjusting the mass of the amorphous phase, which is advantageous to optimize the thickness of the coating layer, thereby obtaining higher ionic conductivity.

[0078] In an embodiment, the amorphous phase is distributed on the outer surface of the positive electrode material, it can be understood that the crystal phase is surrounded and coated between the amorphous phase and the surface of the core, and the crystal phase is in direct contact with the surface of the core, the crystal phase can be partially covered or completely covered by the amorphous phase, when the crystal phase is partially covered by the amorphous phase, the thickness of part of the crystal phase is greater than the thickness of the amorphous phase surrounding it; when the crystal phase is completely covered by the amorphous phase, the thickness of the crystal phase in contact with the surface of the amorphous phase is preferably less than the thickness of the crystal phase in contact with the surface of the core, so that the total thickness of the amorphous phase and the surface crystal phase is close to the thickness of the crystal phase in contact with the surface of the core, thereby making the coating layer more uniform.

[0079] As preferred, the average thickness of the amorphous phase is 1 nm-20 nm, preferably 1 nm-15 nm, by adjusting the thickness of the amorphous phase, which is advantageous to obtain higher ionic conductivity, thereby improving the capacity performance of the battery.

[0080] Further preferably, the thickness ratio of the crystal phase to the amorphous phase is 0.5:1-1.2:1, more preferably 0.8:1-1.1:1, by adjusting the thickness ratio of the crystal phase to the amorphous phase, which is advantageous to optimize the ionic conductivity and mechanical properties, thereby improving the interface stability.

[0081] In an embodiment, the average thickness of the coating layer is 1-20 nm, preferably 1-15 nm. By controlling the thickness of the coating layer to be ultra-thin nanometer level, the ionic conductivity is improved, thereby improving the battery capacity.

[0082] In an embodiment, in the X-ray diffraction pattern of the positive electrode material, the intensity ratio of the (003) crystal face diffraction peak to the (104) crystal face diffraction peak is 1.70-2.40, preferably 1.90-2.40. Compared with the conventional positive electrode material, the intensity ratio of the (003) crystal face diffraction peak to the (104) crystal face diffraction peak is increased, and thus the Li + and the degree of mixing of Ni 2+ is lower than that of the conventional positive electrode material, and the capacity and the first coulombic efficiency are improved.

[0083] The application provides a preparation method of the positive electrode material as described above, comprising the following steps:

[0084] S1, a hydroxide precursor containing doping elements A and doping elements D is prepared by a coprecipitation reaction, the hydroxide precursor is mixed with a first lithium source, and first sintering is performed in an oxygen-containing gas to obtain a first material, and the chemical formula of the first material is Li y Ni x Co z Mn d A e D m O2, 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1;

[0085] S2, the first material is mixed with a polyanion compound, and second sintering is performed in an oxygen-containing gas to obtain a second material, wherein the temperature of the second sintering is greater than or equal to 550°C;

[0086] S3, a second lithium source is mixed with a salt containing M1 and an oxide containing M2, and third sintering is performed in an oxygen-containing gas to obtain the amorphous material;

[0087] S4, the second material is mixed with the amorphous material, and fourth sintering is performed in an oxygen-containing gas to obtain the positive electrode material, wherein the temperature of the fourth sintering is greater than or equal to 400°C, and the temperature of the second sintering is greater than or equal to the temperature of the fourth sintering.

[0088] In step S1, the application does not limit the specific preparation process of the coprecipitation reaction, and a conventional method can be used for preparation, for example: a mixed salt solution and a precipitant are added to water, and a hydroxide precursor is prepared by reaction in a protective gas.

[0089] Preferably, the molar concentration of the mixed salt in the mixed salt solution is 1-3 mol / L, preferably 1-2 mol / L; the molar concentration of the precipitant in water is 5-10 mol / L, preferably 5-8 mol / L; the flow rate of the protective gas is 2-5 L / min, preferably 3-5 L / min.

[0090] Specifically, the mixed salt includes a nickel salt, a cobalt salt, a manganese salt, a salt containing a doping element A, and a salt containing a doping element D, wherein the nickel salt is preferably nickel sulfate hexahydrate; the cobalt salt is preferably cobalt sulfate heptahydrate; the manganese salt is preferably manganese sulfate monohydrate; A is selected from at least one of Mg, Al, Ca, and B, for example: when A is selected from Al, the salt containing the doping element A is preferably aluminum sulfate octadecahydrate; D is selected from at least one of Ti, Ce, Ta, Mo, and Zr, for example: when D is selected from Zr, the salt containing the doping element D is preferably zirconium sulfate tetrahydrate.

[0091] The precipitant includes but is not limited to sodium hydroxide, preferably sodium hydroxide; the protective gas includes but is not limited to at least one of nitrogen and argon, preferably nitrogen; and the water is preferably deionized water.

[0092] The first lithium source includes but is not limited to at least one of lithium carbonate, lithium hydroxide, lithium chloride, lithium fluoride, lithium sulfate, and lithium nitrate.

[0093] In an embodiment, the temperature of the first sintering is 800-1000°C, preferably 800-900°C; and the time is 10-20h, preferably 12-18h.

[0094] In steps S2-S4, by sequentially performing polyanion compound and amorphous phase sintering coating treatment on the first material and regulating the sintering temperature to meet a specific relationship, not only does the amorphous phase material form a molten state on the surface of the material, forming a uniform and continuous crystalline-amorphous composite coating layer on the surface of the positive electrode material, achieving the effect of a mechanically tough CEI-like film, effectively inhibiting the interface side reaction between the sulfide electrolyte and the positive electrode, and improving the structural stability, but also in the process of segmented sintering, part of the elements in the coating layer diffuse into the inner core lattice structure, forming strong covalent bonds with the oxygen atoms in the lattice structure, thereby inhibiting the collapse of the lattice structure caused by deoxidation of the inner core, and ensuring that the inner core crystal structure is not destroyed, improving the crystallinity of the material, and further ensuring high-temperature cycle stability.

[0095] It should be noted that the application does not limit the order of steps S2 and S3, which can be performed in steps S2 first, then in steps S3, or in steps S3 first, then in steps S2, or simultaneously in steps S2 and S3.

[0096] In an embodiment, the first material is crushed before mixing the first material with the polyanion compound before the second sintering, which is beneficial for the polyanion compound to be evenly coated on the surface of the first material.

[0097] Specifically, the temperature of the second sintering is 550-800°C, preferably 650-800°C; and the time is 5-10h, preferably 8-10h.

[0098] The temperature of the third sintering is 900-1200°C, preferably 1000-1200°C; and the time is 4-10h, preferably 8-10h.

[0099] The temperature of the fourth sintering is 400-700°C, preferably 550-700°C; and the time is 5-10h, preferably 8-10h.

[0100] In an embodiment, the mass ratio of the polyanion compound to the first material is 1‰-7‰, wherein the polyanion compound is selected from at least one of lithium salt polyanion compound, ammonium dihydrogen phosphate, and silicic acid, and the lithium salt polyanion compound is selected from at least one of Li3PO4, Li2HPO4, LiH2PO4, Li2SO4, Li2SO3, Li2SiO3, and Li3BO3.

[0101] It should be noted that when the polyanion compound is selected from ammonium dihydrogen phosphate and silicic acid, the polyanion compound forms a lithium salt polyanion compound coating layer on the surface of the first material through residual base reaction under the temperature condition of the second sintering.

[0102] In an embodiment, the molar ratio of Li in the second lithium source to M1 in the salt containing M1 and M2 in the oxide containing M2 is (0.5-1.5):(0.5-1):(0.05-0.1), wherein the second lithium source includes but is not limited to at least one of lithium carbonate, lithium hydroxide, lithium chloride, lithium fluoride, lithium sulfate, and lithium nitrate; M1 is selected from at least one of P and S, and the salt containing M1 is preferably a polyanion compound containing M1, including but not limited to NH4H2PO4 and Li2SO4, for example: when M1 is selected from P, the salt containing M1 is preferably NH4H2PO4; M2 is selected from at least one of Al, Mg, Mo, Zr, and Nb, for example: when M2 is selected from Al, the oxide containing M2 is preferably aluminum oxide.

[0103] It can be understood that the first lithium source and the second lithium source can be the same or different, and the present application does not limit this.

[0104] In an embodiment, the mass ratio of the amorphous phase material to the second material is 0.1 ‰-5 ‰, which is conducive to uniformly coating the amorphous phase material on the surface of the material under sintering conditions higher than the melting temperature of the amorphous phase material, to form a continuous and uniform coating layer.

[0105] The application provides a positive electrode sheet and a sulfide solid-state battery. It can be understood that the positive electrode sheet comprises a current collector and a positive electrode active layer disposed on the current collector, and the positive electrode active layer comprises the positive electrode material as described above. The current collector includes but is not limited to a lithium foil.

[0106] It should be noted that the application does not limit the specific components of the positive electrode active layer, the preparation method of the positive electrode sheet, and the type of the negative electrode sheet in the solid-state battery. The positive electrode active layer also includes a conductive agent and a binder; the positive electrode sheet can be prepared by dry or wet method; and the material of the negative electrode sheet in the solid-state battery includes but is not limited to lithium metal, alloy, graphite or silicon.

[0107] Therefore, the use of the positive electrode material described in the application in the sulfide solid-state battery can significantly improve the capacity, the first coulombic efficiency and the high-temperature cycle stability of the sulfide solid-state battery.

[0108] It can be understood that the power consumption equipment using the above-mentioned sulfide solid-state battery includes but is not limited to electric vehicles, electric tools, electronic products, energy storage systems, office equipment, etc., and the application does not limit this.

[0109] In the following, the positive electrode material, its preparation method and application will be further described through the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the application and should not be regarded as limiting the scope of the application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0110] Example 1

[0111] Nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, zirconium sulfate tetrahydrate, and aluminum sulfate octadecahydrate were dissolved in deionized water to prepare a mixed salt solution, wherein the molar ratio of nickel, cobalt, manganese, zirconium and aluminum was 0.80:0.12:0.05:0.02:0.01, the molar concentration of the mixed salt in the mixed salt solution was 2 mol / L, and the mixed salt solution was added to a reaction kettle containing deionized water through a peristaltic pump. Sodium hydroxide was added at the same time, so that the sodium hydroxide mixed with the deionized water in the reaction kettle to form a sodium hydroxide solution with a concentration of 8 mol / L. Nitrogen gas with a flow rate of 3 L / min was introduced as a protective gas. The co-precipitation reaction was carried out at a temperature of 50°C under stirring. The reaction product was washed, suction filtered and dried to obtain a hydroxide precursor.

[0112] The 1 kg hydroxide precursor and 461 g lithium hydroxide monohydrate are uniformly mixed in a mixer for 30 min, and then the mixture is transferred into a box furnace, oxygen is introduced, and sintering is performed at 850 ℃ for 12 h. After discharging, crushing is performed to obtain a first material.

[0113] The NH4H2PO4, Al2O3, and Li2CO3 are uniformly mixed and then transferred into a box furnace, air is introduced, and sintering is performed at 1000 ℃ for 6 h to obtain an amorphous material Li-P-Al-O, wherein the molar ratio of Li:P:Al is 0.75:0.5:0.05.

[0114] The 800 g first material and 2.376 g NH4H2PO4 are mixed in a high-speed mixer for 30 min and then transferred into a box furnace, oxygen is introduced, and sintering is performed at 700 ℃ for 8 h to obtain a second material, wherein the mass fraction of P in the second material relative to the first material is 0.8 ‰.

[0115] The 500 g second material and 1 g amorphous material are uniformly mixed and then transferred into a box furnace, oxygen is introduced, and sintering is performed at 550 ℃ for 8 h to obtain a positive electrode material, wherein the mass fraction of the amorphous material in the positive electrode material relative to the first material is 2 ‰.

[0116] Example 2

[0117] Nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, aluminum sulfate octadecahydrate, and titanium sulfate are dissolved in deionized water to prepare a mixed salt solution, wherein the molar ratio of nickel, cobalt, manganese, aluminum, and titanium is 0.81:0.12:0.05:0.01:0.01, the molar concentration of the mixed salts in the mixed salt solution is 3 mol / L, and the mixed salt solution is added to a reaction kettle containing deionized water through a peristaltic pump. Sodium hydroxide is added at the same time, so that the sodium hydroxide is mixed with the deionized water in the reaction kettle to form a sodium hydroxide solution with a concentration of 6 mol / L. Nitrogen gas with a flow rate of 5 L / min is introduced as a protective gas, and the co-precipitation reaction is performed at a temperature of 45 ℃ under stirring. The reaction product is washed, suction filtered, and dried to obtain a hydroxide precursor.

[0118] The 1 kg hydroxide precursor and 410 g lithium carbonate are uniformly mixed in a mixer for 30 min, and then the mixture is transferred into a box furnace, oxygen is introduced, and sintering is performed at 800 ℃ for 12 h. After discharging, crushing is performed to obtain a first material.

[0119] The NH4H2PO4, ZrO2, and Li2CO3 are uniformly mixed and then transferred into a box furnace, air is introduced, and sintering is performed at 1100 ℃ for 8 h to obtain an amorphous material Li-P-Zr-O, wherein the molar ratio of Li:P:Zr is 1:0.5:0.05.

[0120] The 800g first material is mixed with 3.34g silicic acid in a high-speed mixer for 30min, then transferred to a box furnace, oxygen is introduced, and sintered at 700℃ for 8h to obtain a second material, and the mass fraction of Si in the second material relative to the first material is 1.5 ‰.

[0121] The 500g second material is mixed with 1.5g amorphous phase material uniformly, then transferred to a box furnace, oxygen is introduced, and sintered at 600℃ for 10h to obtain a positive electrode material, and the mass fraction of amorphous phase material in the positive electrode material relative to the first material is 3 ‰.

[0122] Example 3

[0123] Nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, magnesium sulfate, and titanium sulfate are dissolved in deionized water to prepare a mixed salt solution, wherein the molar ratio of nickel, cobalt, manganese, magnesium, and titanium is 0.90:0.06:0.02:0.01:0.01, the molar concentration of the mixed salt in the mixed salt solution is 1 mol / L, and the mixed salt solution is added to a reaction kettle containing deionized water through a peristaltic pump, while sodium hydroxide is added, so that the sodium hydroxide is mixed with the deionized water in the reaction kettle to form a sodium hydroxide solution with a concentration of 5 mol / L, nitrogen gas with a flow rate of 3L / min is introduced as a protective gas, and the co-precipitation reaction is carried out by stirring at a temperature of 55℃. The reaction product is washed, suction filtered, and dried to obtain a hydroxide precursor.

[0124] The 1kg hydroxide precursor and 743g lithium chloride are uniformly mixed in a mixer for 30min, and then the mixture is transferred to a box furnace, oxygen is introduced, and sintered at 870℃ for 10h, and after discharging, the mixture is crushed to obtain a first material.

[0125] Li2SO4 and MgO are mixed uniformly, then transferred to a box furnace, air is introduced, and sintered at 1000℃ for 10h to obtain an amorphous phase material Li-S-Mg-O, wherein the molar ratio of Li:S:Mg is 1:0.5:0.08.

[0126] The 800g first material is mixed with 5.48g Li2SO4 in a high-speed mixer for 30min, then transferred to a box furnace, oxygen is introduced, and sintered at 750℃ for 10h to obtain a second material, and the mass fraction of S in the second material relative to the first material is 2 ‰.

[0127] The 500g second material is mixed with 2g amorphous phase material uniformly, then transferred to a box furnace, oxygen is introduced, and sintered at 650℃ for 10h to obtain a positive electrode material, and the mass fraction of amorphous phase material in the positive electrode material relative to the first material is 4 ‰.

[0128] Example 4

[0129] Example 4 differs from Example 1 in that the molar ratio of nickel, cobalt, manganese, zirconium, aluminum in the mixed salt solution is 0.81:0.12:0.05:0.01:0.01.

[0130] Example 5

[0131] Example 5 differs from Example 1 in that 800g of the first material is mixed with 4.46g of NH4H2PO4 for sintering, so that the mass fraction of P in the second material relative to the first material is 1.5 ‰.

[0132] Example 6

[0133] Example 6 differs from Example 1 in that 500g of the second material is mixed with 2.5g of amorphous material for sintering, so that the mass fraction of amorphous material in the positive electrode material relative to the first material is 5 ‰.

[0134] Comparative Example 1

[0135] Comparative Example 1 differs from Example 1 in that no amorphous material is prepared for secondary coating, and the second material is directly used as the positive electrode material.

[0136] Comparative Example 2

[0137] Comparative Example 2 differs from Example 1 in that nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, and aluminum sulfate octadecahydrate are dissolved in deionized water to form a mixed salt solution, and the molar ratio of nickel, cobalt, manganese, and aluminum is 0.82:0.12:0.05:0.01.

[0138] Comparative Example 3

[0139] Comparative Example 3 differs from Example 1 in that nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, and zirconium sulfate tetrahydrate are dissolved in deionized water to form a mixed salt solution, and the molar ratio of nickel, cobalt, manganese, and zirconium is 0.81:0.12:0.05:0.02.

[0140] Comparative Example 4

[0141] Comparative Example 4 differs from Example 1 in that Al2O3 and Li2CO3 are mixed uniformly and then transferred to a box furnace, air is introduced, and sintering is performed at 1000°C for 6h to obtain amorphous material Li-Al-O, wherein the molar ratio of Li:Al is 0.75:0.05.

[0142] Comparative Example 5

[0143] Comparative Example 5 differs from Example 1 in that NH4H2PO4 and Li2CO3 are mixed uniformly and then transferred to a box furnace, air is introduced, and sintering is performed at 1000°C for 6h to obtain amorphous material Li-P-O, wherein the molar ratio of Li:P is 0.75:0.5.

[0144] Comparative Example 6

[0145] Comparative Example 6 differs from Example 1 in that the second sintering temperature is 400℃, the time is 6h, and the fourth sintering temperature is 300℃, the time is 6h.

[0146] Comparative Example 7

[0147] Comparative Example 7 differs from Example 1 in that the fourth sintering temperature is 750℃.

[0148] The positive electrode material prepared in Example 1 and Comparative Example 1 was subjected to SEM test, and the results are shown in FIG. 1(a) and FIG. 1(b) respectively. It can be seen that the surface of the coated positive electrode is smooth, indicating that the coating layer is thin and uniform.

[0149] The positive electrode material prepared in Example 1 was subjected to EDS test, and the results are shown in FIG. 2. It can be seen that the mapping of P element almost overlaps with the shape of the positive electrode material particles, indicating that the coating layer on the surface of the positive electrode material is uniform.

[0150] The surface of the positive electrode material prepared in Example 1 was subjected to TEM test, and the results are shown in FIG. 3. The coating layer with a thickness of about 5nm-10nm can be clearly observed on the surface of the particles, and the surface is smooth, proving that the coating layer uniformly and completely coats the surface of the positive electrode material in the form of a film.

[0151] The positive electrode materials prepared in Example 1 and Comparative Example 1 were subjected to XRD test, and the results are shown in FIG. 4. It can be seen that the positive electrode material prepared in Example 1 does not have new diffraction peaks, indicating that the layered structure of the positive electrode material is well preserved, and because the coating amount is small, the coating layer will not affect the crystal structure of the positive electrode material.

[0152] The positive electrode materials prepared in Examples 1 to 6 and Comparative Examples 1 to 7 were subjected to characterization test, and the results are shown in Table 1 and Table 2. Among them, the chemical formula is obtained according to ICP test; the intensity ratio of (003) crystal face to (104) crystal face is obtained according to XRD test; the cross section of the positive electrode material prepared in Example 1 is shown in FIG. 5, and the element composition is obtained by taking points on the cross section from the center to the outside for EDS test, and then the ratio of the thickness of the X-rich layer to the radius of the core can be calculated, and the calculation results are shown in Table 1.

[0153] Table 1

[0154] Table 2

[0155] According to Table 2, the I(003) / I(104) of the examples is larger than that of the comparative examples, indicating that the cationic disordering is smaller.

[0156] The positive electrode materials prepared in Examples 1 to 6 and Comparative Examples 1 to 7 were made into positive electrode sheets and assembled into solid-state batteries for performance testing, and the specific preparation method and testing method are as follows:

[0157] The positive electrode material, sulfide electrolyte Li6PS5Cl and conductive agent VGCF were mixed uniformly at a mass ratio of 85:15:1, and the mixing method was ball milling, wherein the ball milling speed was 250 r / min, the ball milling time was 4 h, and the ball-to-material ratio was 4:1. After uniform mixing, the binder PTFE was added and ground into a sheet, and then kneaded and thinned on a hot roller press to obtain a positive electrode sheet. The mass of the binder was 1% of the mass of the mixed material. Graphite was used as the negative electrode sheet, 150 mg of the sulfide electrolyte Li6PS5Cl was weighed and uniformly laid in the mold battery sleeve, and an electrolyte sheet was made at 200 MPa, and then the positive electrode sheet and the negative electrode sheet were placed on both sides of the electrolyte sheet, and the positive electrode and the negative electrode were compounded with the electrolyte sheet at 400 MPa to prepare a sulfide all-solid-state battery.

[0158] The sulfide all-solid-state batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 7 were subjected to float charging test, and the float charging test conditions were 0.1C charging and discharging for one cycle at 2.5V-4.25V, 0.1C charging to 4.25V constant voltage charging for 10h and then discharging, and the capacity in the constant voltage section was counted under different charging and discharging cycles, and the results are shown in Table 3.

[0159] Table 3

[0160] According to Table 3, the irreversible capacity of the sulfide all-solid-state batteries prepared in Examples 1 to 6 is reduced, which indicates that the interface side reaction is effectively inhibited.

[0161] The sulfide all-solid-state batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 7 were run under a test pressure of about 100 MPa, and the test conditions were 0.1C, 0.2C, 0.5C, 1C, 2C and 3C respectively for two cycles at a high temperature of 60℃, and then restored to 0.5C test cycle, and the voltage window was 2.5V-4.25V; the test method of potential difference was CV. The test results are shown in Table 4, wherein the test data comparison graphs of Example 1 and Comparative Example 1 are shown in Figures 6, 7 and 8.

[0162] Table 4

[0163] According to FIGS. 6-8 and Table 4, compared with Comparative Examples 1-7, the redox potential difference of the sulfide all-solid-state batteries prepared in Examples 1-6 is smaller, indicating that the interface side reaction is effectively inhibited, and the reversibility of the electrochemical reaction is higher; the first circle coulombic efficiency is improved, and the charge-discharge capacity is increased, further indicating that the coating layer structure provided in the application effectively inhibits the interface side reaction; the capacity can be maintained at about 85% at the highest after 100 cycles at 60°C high temperature environment, significantly improving the high temperature cycle stability.

[0164] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but it should be considered that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in contradictions.

[0165] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A cathode material for solid-state batteries, wherein, The cathode material includes a core and a coating layer covering the surface of the core. The coating layer is a composite state of crystalline and amorphous phases, and the amorphous phase is distributed on the outer surface of the cathode material. The lattice parameter c / a of the cathode material is 4.935-4.

950. The chemical formula of the core is Li y Ni x Co z Mn d A e D m O2, wherein 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1, A is selected from at least one of Mg, Al, Ca, and B, D is selected from at least one of Ti, Ce, Ta, Mo, and Zr, and the surface layer of the core is an X-rich layer, where X is selected from at least one of P, S, Si, B, Al, Mg, Mo, Zr, and Nb; In the coating layer, the crystalline phase material is a lithium salt polyanionic compound, and the amorphous phase material is Li-M1-M2-O, wherein M1 is selected from at least one of P and S, and M2 is selected from at least one of Al, Mg, Mo, Zr, and Nb.

2. The cathode material according to claim 1, wherein, c / a is 4.94-4.95; and / or, 1≤y≤1.02, 0.8≤x≤0.95, 0.05≤z≤0.2, 0.01≤d≤0.2, 0.01≤e<0.05, 0.01≤m<0.05, A is selected from at least one of Mg, Al, and B, D is selected from at least one of Ti, Ta, and Zr, and X is selected from at least one of P, S, Si, Al, Mg, and Zr.

3. The cathode material according to any one of claims 1-2, wherein, In the amorphous phase, the molar ratio of Li to M1 and M2 is (0.5-1.5):(0.5-1):(0.05-0.1).

4. The cathode material according to claim 3, wherein, In the amorphous phase, the molar ratio of Li to M1 and M2 is (1-1.5):(0.5-0.7):(0.05-0.08).

5. The cathode material according to any one of claims 1-4, wherein, The lithium salt polyanionic compound is selected from at least one of Li3PO4, Li2HPO4, LiH2PO4, Li2SO4, Li2SO3, Li2SiO3, and Li3BO3.

6. The cathode material according to claim 5, wherein, The lithium salt polyanionic compound is selected from at least one of Li3PO4, Li2SO4, and Li2SiO3.

7. The cathode material according to any one of claims 1-6, wherein, The mass of the amorphous phase is 0.1‰-5‰ of the core; And / or, the mass of the non-oxygen element of the polyanion in the lithium salt polyanionic compound is 0.2‰-2‰ of the core.

8. The cathode material according to claim 7, wherein, The mass of the amorphous phase is 1‰-4‰ of the core; And / or, the mass of the non-oxygen element of the polyanion in the lithium salt polyanionic compound is 0.5‰-1.5‰ of the core.

9. The cathode material according to any one of claims 1-8, wherein, The crystal phase has an island-like structure, which covers at least a portion of the surface of the core, and the average undulation thickness of the island-like structure is 1 nm-20 nm. And / or, the amorphous phase is distributed on the outer surface of the cathode material, and the average thickness of the amorphous phase is 1nm-20nm; And / or, the thickness ratio of the crystalline phase to the amorphous phase is 0.5:1-1.2:1; And / or, the average thickness of the coating layer is 1nm-20nm; And / or, the ratio of the thickness of the X-rich layer to the radius of the core is 0.05:1-0.5:

1.

10. The cathode material according to claim 9, wherein, The average undulation thickness of the island-like structure is 1nm-15nm; And / or, the average thickness of the amorphous phase is 1 nm-15 nm; And / or, the thickness ratio of the crystalline phase to the amorphous phase is 0.8:1-1.1:1; And / or, the average thickness of the coating layer is 1nm-15nm; And / or, the ratio of the thickness of the X-rich layer to the radius of the core is 0.1:1-0.3:

1.

11. The cathode material according to any one of claims 1-10, wherein, In the X-ray diffraction pattern of the cathode material, the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak is 1.70-2.

40.

12. The cathode material according to claim 11, wherein, The intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak is 1.90-2.

40.

13. A method for preparing a cathode material according to any one of claims 1 to 12, wherein, Includes the following steps: A hydroxide precursor containing dopant elements A and D was prepared by co-precipitation reaction. The hydroxide precursor was then mixed with a first lithium source and subjected to a first sintering in an oxygen-containing gas to obtain a first material. The chemical formula of the first material is Li. y Ni x Co z Mn d A e D m O2, 1≤y≤1.03, 0.5≤x≤0.96, 0≤z≤0.4, 0≤d≤0.4, 0.01≤e<0.1, 0.01≤m<0.1; The first material is mixed with a polyanionic compound and sintered a second time in an oxygen-containing gas to obtain the second material, wherein the temperature of the second sintering is greater than or equal to 550°C. The second lithium source is mixed with a salt containing M1 and an oxide containing M2, and then sintered for the third time in an oxygen-containing gas to obtain the amorphous phase material. The second material is mixed with the amorphous phase material and sintered for the fourth time in an oxygen-containing gas to obtain the cathode material, wherein the temperature of the fourth sintering is greater than or equal to 400°C, and the temperature of the second sintering is greater than or equal to the temperature of the fourth sintering.

14. The method for preparing the cathode material according to claim 13, wherein, The coprecipitation reaction includes adding a mixed salt solution and a precipitant to water and reacting them in a protective gas to obtain a hydroxide precursor. The molar concentration of the mixed salt in the mixed salt solution is 1 mol / L-3 mol / L, the molar concentration of the precipitant in the water is 5 mol / L-10 mol / L, and the flow rate of the protective gas is 2 L / min-5 L / min.

15. The method for preparing the cathode material according to claim 14, wherein, The molar concentration of the mixed salt in the mixed salt solution is 1 mol / L-2 mol / L, the molar concentration of the precipitant in water is 5 mol / L-8 mol / L, and the flow rate of the protective gas is 3 L / min-5 L / min.

16. The method for preparing the cathode material according to any one of claims 13-15, wherein, The polyanionic compound is selected from at least one of lithium salt polyanionic compounds, ammonium dihydrogen phosphate, and silicic acid; And / or, the mass of the polyanionic compound is 1‰-7‰ of the first material; And / or, the mass of the amorphous phase material is 0.1‰-5‰ of the second material; And / or, the molar ratio of Li in the second lithium source to M1 in the salt containing M1 and M2 in the oxide containing M2 is (0.5-1.5):(0.5-1):(0.05-0.1).

17. The method for preparing the cathode material according to any one of claims 13-16, wherein, The first sintering temperature is 800℃-1000℃, and the time is 10h-20h; And / or, the second sintering temperature is 550℃-800℃, and the time is 5h-10h; And / or, the temperature of the third sintering is 900℃-1200℃, and the time is 4h-10h; And / or, the fourth sintering temperature is 400℃-700℃, and the time is 5h-10h.

18. The method for preparing the cathode material according to claim 17, wherein, The first sintering temperature is 800℃-900℃, and the time is 12h-18h; And / or, the second sintering temperature is 650℃-800℃, and the time is 8h-10h; And / or, the temperature of the third sintering is 1000℃-1200℃, and the time is 8h-10h; And / or, the fourth sintering temperature is 550℃-700℃, and the time is 8h-10h.

19. A positive electrode plate, wherein, Includes the cathode material as described in any one of claims 1 to 12.

20. A sulfide solid-state battery, wherein, Including the positive electrode as described in claim 19.

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