Solid electrolyte material and preparation method therefor, positive electrode active material and preparation method therefor, positive electrode sheet, battery, and electric device

Abstract

The present invention relates to the technical field of batteries. Disclosed are a solid electrolyte material and a preparation method therefor, a positive electrode active material and a preparation method therefor, a positive electrode sheet, a battery, and an electric device. The solid electrolyte material is of an NASICON crystal structure, and in an X-ray diffraction pattern of the solid electrolyte material, the 2θ value of a diffraction peak representing LiTi2(PO4)3 is reduced by 0.02°-0.06° compared to the 2θ value of the corresponding diffraction peak in a standard pattern of LiTi2(PO4)3. Hence, by using the solid electrolyte material, a battery loaded with same has excellent rate performance.

Description

Solid-state electrolyte material and preparation method thereof, positive electrode active material and preparation method thereof, positive electrode sheet, battery and electric device

[0001] Priority information

[0002] The present application claims priority to and the benefit of Chinese Patent Application No. 202410814749.3, filed on June 21, 2024, and which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the field of batteries, and particularly relates to a solid-state electrolyte material and a preparation method thereof, a positive electrode active material and a preparation method thereof, a positive electrode sheet, a battery and an electric device. BACKGROUND

[0004] The range anxiety and battery safety problem have become the pain point and main bottleneck restricting the development of new energy vehicles. The iteration innovation of the next generation of higher energy density and safer power batteries depends on the technical breakthrough of solid-state batteries. As the core material of solid-state batteries, the comprehensive performance and industrialization progress of solid-state electrolyte materials are the key to the development of solid-state batteries. At present, the solid-state electrolyte materials with industrialization prospects mainly include three systems of polymers, sulfides and oxides. Although the sulfide electrolyte has high conductivity, it has high manufacturing cost and unstable structure, and faces great challenges in large-scale production and vehicle loading. The polymer solid-state electrolyte is soft and easy to process, but has low room temperature ionic conductivity and is not resistant to voltage above 4.0V. The NASICON type oxide solid-state electrolyte has stable structure, low cost and high voltage window, and is easy to realize the iteration from semi-solid, quasi-solid to full-solid battery. However, the ionic conductivity of the current oxide solid-state electrolyte is still lower than that of the electrolyte, which affects the rate performance and cycle performance of the battery.

[0005] SUMMARY

[0006] The present application aims to at least partially solve one of the technical problems in the related art. To this end, one object of the present application is to provide a solid-state electrolyte material and a preparation method thereof, a positive electrode active material and a preparation method thereof, a positive electrode sheet, a battery and an electric device, which has high ionic conductivity, so that the battery containing the same has excellent rate performance.

[0007] In one aspect of the present application, the present application provides a solid-state electrolyte material, which has a NASICON crystal structure, and in the X-ray diffraction spectrum of the solid-state electrolyte material, the 2theta value of the diffraction peak representing LiTi2(PO4)3 is reduced by 0.02°-0.06° compared with the 2theta value of the corresponding diffraction peak in the standard spectrum of LiTi2(PO4)3.

[0008] The 2θ value of the diffraction peak representing LiTi2(PO4)3 of the solid electrolyte material according to the embodiments of the present application is reduced by 0.02°-0.06° compared with the 2θ value of the corresponding diffraction peak in the standard spectrum of LiTi2(PO4)3, so that the cell parameter and the cell volume of the solid electrolyte material are increased, thereby the transport channel of lithium ions is widened, the ionic conductivity of the solid electrolyte material can be improved, and the battery containing the same has excellent rate performance.

[0009] In addition, the solid electrolyte material according to the above embodiments of the present application can also have the following additional technical features:

[0010] In some embodiments of the present application, the diffraction peaks representing LiTi2(PO4)3 include diffraction peak (012), diffraction peak (104), diffraction peak (113) and diffraction peak (024). Thereby, the ionic conductivity of the solid electrolyte material can be further improved, and the battery containing the same has excellent rate performance.

[0011] In some embodiments of the present application, the cell parameter of the solid electrolyte material is increased by an a value compared with the cell parameter of LiTi2(PO4)3. Thereby, the ionic conductivity of the solid electrolyte material can be further improved, and the battery containing the same has excellent rate performance.

[0012] In some embodiments of the present application, the cell volume of the solid electrolyte material is increased compared with the cell volume of LiTi2(PO4)3. Thereby, the ionic conductivity of the solid electrolyte material can be further improved, and the battery containing the same has excellent rate performance.

[0013] In some embodiments of the present application, the solid electrolyte material has a diffraction peak (721) at a diffraction angle 2θ value of 27.7°-27.8° in the X-ray diffraction spectrum, the peak intensity of the diffraction peak (721) is I1, the peak intensity of the diffraction peak (113) is I2, and 0.1≤I1 / I2≤0.5. Thereby, the ionic conductivity of the solid electrolyte material can be further improved, and the battery containing the same has excellent rate performance.

[0014] In some embodiments of the present application, the ionic conductivity of the solid electrolyte material is greater than or equal to 5×10 -4 S / cm, which can be greater than or equal to 1×10 -3 S / cm. Thereby, the ionic conductivity of the solid electrolyte material can be further improved, and the battery containing the same has excellent rate performance.

[0015] In some embodiments of the present application, the average particle size of the solid electrolyte material is 0.05 μm-0.5 μm, which can be preferably 0.05 μm-0.1 μm. In this way, the ionic conductivity of the solid electrolyte material can be further improved, so that the battery containing the same has excellent rate performance.

[0016] In some embodiments of the present application, the pH value of the solid electrolyte material is 6-10 at 25°C. In this way, the ionic conductivity of the solid electrolyte material can be further improved, so that the battery containing the same has excellent rate performance.

[0017] In some embodiments of the present application, the solid electrolyte material comprises:

[0018] Li x M 1 y M 2 z Ti u (PO4) v1 (P2O7) v2 ,

[0019] wherein, M 1 comprises at least one of the first main group elements other than Li, M 2 comprises at least one of the metal elements having a positive trivalence, 1≤x<4, 0.1≤y≤0.5, 0.2<z≤0.5, 1<u≤5.5, 2≤v1≤6, 0.1<v2≤3. In this way, the ionic conductivity of the solid electrolyte material can be further improved, so that the battery containing the same has excellent rate performance.

[0020] In some embodiments of the present application, M 1 comprises at least one of K, Rb and Cs. In this way, the ionic conductivity of the solid electrolyte material can be further improved, so that the battery containing the same has excellent rate performance.

[0021] In some embodiments of the present application, M 2 comprises at least one of V, La and Cr. In this way, the ionic conductivity of the solid electrolyte material can be further improved, so that the battery containing the same has excellent rate performance.

[0022] In the second aspect of the present application, a method for preparing the above-mentioned solid electrolyte material is provided, comprising:

[0023] mixing a M 2 source, a Ti source, a PO4 3- source, a P2O7 4- source, a precipitating agent and a solvent, and obtaining a precursor after co-precipitation and filtration;

[0024] The precursor is combined with the Li source and M 1 The source is mixed and sintered in an oxygen-containing atmosphere to obtain a solid electrolyte material.

[0025] Therefore, the above-mentioned solid electrolyte material can be prepared using this method, introducing pyrophosphate ions into the unit cell of the conventional LiTi2(PO4)3 structure, and the doping element M 1 and M 2 This increases the cell parameters and cell volume, thereby widening the lithium-ion transport channels and improving the ionic conductivity of solid electrolyte materials, resulting in batteries containing them having excellent rate performance.

[0026] In some embodiments of the present invention, the oxygen-containing atmosphere includes oxygen or air. This further improves the ionic conductivity of the solid electrolyte material, resulting in batteries containing it exhibiting excellent rate performance.

[0027] In some embodiments of the present invention, the sintering temperature is 600℃-800℃, and the sintering time is 4h-10h. This further improves the ionic conductivity of the solid electrolyte material, resulting in batteries containing it exhibiting excellent rate performance.

[0028] In some embodiments of the present invention, the M 1 Sources include those containing M 1 oxides containing M 1 Phosphates containing M 1 sulfates, containing M 1 Chlorides, containing M 1 nitrates and containing M 1 At least one of the carbonates. This can further improve the ionic conductivity of solid electrolyte materials, resulting in batteries containing them exhibiting excellent rate performance.

[0029] In some embodiments of the present invention, the M 2 Sources include those containing M 2 oxides containing M 2 Phosphates containing M 2 sulfates, containing M 2 Chlorides, containing M 2 nitrates and containing M 2 At least one of the carbonates. This can further improve the ionic conductivity of solid electrolyte materials, resulting in batteries containing them exhibiting excellent rate performance.

[0030] In some embodiments of the present invention, the Ti source includes at least one selected from Ti-containing phosphates, Ti-containing acetates, Ti-containing sulfates, Ti-containing chlorides, Ti-containing nitrates, and Ti-containing carbonates. This further improves the ionic conductivity of the solid electrolyte material, resulting in batteries containing it exhibiting excellent rate performance.

[0031] In some embodiments of the present invention, the PO4 3- The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4. This can further improve the ionic conductivity of solid electrolyte materials, resulting in batteries containing them exhibiting excellent rate performance.

[0032] In some embodiments of the present invention, the Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate. This further improves the ionic conductivity of the solid electrolyte material, resulting in batteries containing it exhibiting excellent rate performance.

[0033] In some embodiments of the present invention, the P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7. This can further improve the ionic conductivity of solid electrolyte materials, resulting in batteries containing them exhibiting excellent rate performance.

[0034] In some embodiments of the present invention, the precipitant includes at least one of sodium hydroxide, sodium carbonate, and ammonia. This further improves the ionic conductivity of the solid electrolyte material, resulting in batteries containing it exhibiting excellent rate performance.

[0035] In a third aspect, the present invention provides a positive electrode active material comprising a substrate and a coating layer disposed on at least a portion of the surface of the substrate, the coating layer comprising the solid electrolyte material described in the first aspect of the present invention or a solid electrolyte material prepared using the method described in the second aspect. Thus, the surface of the positive electrode active material is coated with a solid electrolyte material, the solid electrolyte material introducing pyrophosphate ions into the unit cell of a conventional LiTi2(PO4)3 structure, and doped with element M. 1 and M 2 This increases the cell parameters and cell volume, thereby widening the lithium-ion transport channels and improving the ionic conductivity of the positive electrode active material, resulting in batteries containing it having excellent rate performance.

[0036] In some embodiments of the present invention, the thickness of the coating layer is 10nm-500nm, thereby the prepared positive electrode active material has high ionic conductivity, which makes the battery containing it have excellent rate performance.

[0037] In some embodiments of the present invention, the mass percentage of the solid electrolyte material is 0.01%-1% based on the total mass of the positive electrode active material. As a result, the prepared positive electrode active material has high ionic conductivity, which makes the battery containing it have excellent rate performance.

[0038] In some embodiments of the present invention, the temperature corresponding to the exothermic peak in the DSC test curve of the positive electrode active material is ≥220℃. Therefore, the prepared positive electrode active material has high ionic conductivity, resulting in batteries containing it exhibiting excellent rate performance.

[0039] In some embodiments of the present invention, the matrix includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate. As a result, the prepared positive electrode active material has high ionic conductivity, which makes the battery containing it have excellent rate performance.

[0040] In a fourth aspect, the present invention provides a method for preparing the positive electrode active material described in the third aspect, comprising:

[0041] Solid electrolyte materials are ground into nanoparticles and mixed with a matrix to obtain a mixture.

[0042] The mixture is heat-treated in an oxygen-containing atmosphere to obtain a positive electrode active material.

[0043] Thus, the prepared positive electrode active material includes a substrate and a coating layer disposed on at least a portion of the surface of the substrate, the coating layer comprising the solid electrolyte material described in the first aspect of the present invention or a solid electrolyte material prepared by the method described in the second aspect. Thus, the surface of the positive electrode active material is coated with a solid electrolyte material, the solid electrolyte material introducing pyrophosphate ions into the unit cell of a conventional LiTi2(PO4)3 structure, and doped with element M. 1 and M 2 This increases the cell parameters and cell volume, thereby widening the lithium-ion transport channels and improving the ionic conductivity of solid electrolyte materials, resulting in batteries containing them having excellent rate performance.

[0044] In some embodiments of the present invention, the oxygen-containing atmosphere includes oxygen or air;

[0045] Optionally, the heat treatment temperature is 300℃-500℃, and the heat treatment time is 2h-8h.

[0046] Therefore, the prepared positive electrode active material has high ionic conductivity, which makes the battery containing it have excellent rate performance.

[0047] In a fifth aspect of the invention, the present invention provides a positive electrode sheet comprising the positive electrode active material described in the third aspect of the invention, or a positive electrode active material prepared by the method described in the fourth aspect of the invention.

[0048] In a sixth aspect, the present invention provides a battery comprising at least one of the solid electrolyte material described in the first aspect, the solid electrolyte material prepared by the method described in the second aspect, and the positive electrode sheet described in the fifth aspect. Therefore, the battery exhibits excellent electrochemical performance.

[0049] In a seventh aspect, the present invention provides an electrical device comprising the battery described in the sixth aspect of the present invention.

[0050] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0051] Figure 1 is the XRD pattern of the solid electrolyte material of Comparative Example 1 and Examples 1-4 of this application at 2θ values ​​of 10°-70°;

[0052] Figure 2 is the XRD pattern of the solid electrolyte material of Comparative Example 1 and Examples 1-4 of this application at a 2θ value of 10°-30°;

[0053] Figure 3 is a SEM image of the solid electrolyte material in Example 1 of this application. Detailed Implementation

[0054] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0056] In one aspect of the present invention, a solid electrolyte material is provided, wherein the solid electrolyte material has a NASICON crystal structure, and the 2θ value of the diffraction peak representing LiTi2(PO4)3 in the X-ray diffraction pattern of the solid electrolyte material is reduced by 0.02°-0.06° compared with the 2θ value of the corresponding diffraction peak in the standard pattern of LiTi2(PO4)3.

[0057] As an example, the 2θ value of the diffraction peak representing LiTi2(PO4)3 can be reduced by 0.02°, 0.03°, 0.04°, 0.05°, 0.06°, etc., compared to the corresponding 2θ value of the diffraction peak in the standard spectrum (PDF#35-0754) of LiTi2(PO4)3.

[0058] It is understood that in the X-ray diffraction pattern of solid electrolyte materials, there may be one or more diffraction peaks representing LiTi2(PO4)3. When there are multiple peaks, the 2θ value of each diffraction peak is reduced by 0.02°-0.06° compared with the corresponding diffraction peak in the standard pattern. In addition, when there are multiple peaks, if only one diffraction peak is reduced by 0.02°-0.06° compared with the corresponding diffraction peak in the standard pattern, or if not all diffraction peaks are reduced by 0.02°-0.06° compared with the corresponding diffraction peak in the standard pattern, it is also within the scope of protection of this application.

[0059] The inventors discovered that in the X-ray diffraction pattern of solid electrolyte materials, the 2θ value of the diffraction peak representing LiTi2(PO4)3 is reduced by 0.02°-0.06° compared to the corresponding 2θ value in the standard LiTi2(PO4)3 pattern. According to Bragg's equation 2dsinθ=nλ, for X-ray diffraction, when the optical path difference is an integer multiple of the wavelength, the diffraction lines of the crystal plane will be enhanced, where d is the interplanar spacing, θ is the incident ray, the angle between the reflected ray and the reflecting crystal plane, λ is the wavelength, and n is the reflection order. With a fixed detection wavelength, a decrease in the 2θ value means an increase in the interplanar spacing d, and the corresponding cell parameters and volume will also increase accordingly. Therefore, the obtained solid electrolyte material crystal has larger cell parameters and cell volume compared to the standard LiTi2(PO4)3 crystal. As a result, the lithium-ion transport channel is widened, which can improve the ionic conductivity of the solid electrolyte material, making the battery containing it have excellent rate performance.

[0060] According to an embodiment of the present invention, the diffraction peaks representing LiTi2(PO4)3 include diffraction peak (012), diffraction peak (104), diffraction peak (113), and diffraction peak (024), and the 2θ values ​​corresponding to the above diffraction peaks are 14.685°, 20.843°, 24.491°, and 29.641°, respectively. Thus, compared with the 2θ values ​​corresponding to the standard spectrum, the above diffraction peaks are reduced by 0.02°-0.06°, which can further improve the ionic conductivity of the solid electrolyte material, so that the battery containing it has excellent rate performance.

[0061] According to an embodiment of the present invention, the cell parameter α of the solid electrolyte material is increased compared to that of LiTi2(PO4)3. The c value increases That is, the cell parameters of the solid electrolyte material in this embodiment of the invention are larger than those of standard LiTi2(PO4)3; for example, the a value can be increased. The value of c can be increased. Therefore, the solid electrolyte material of this embodiment has larger cell parameters and cell volume compared to the standard LiTi2(PO4)3 crystal. As a result, the lithium ion transport channels are widened, which can improve the ionic conductivity of the solid electrolyte material and make the battery containing it have excellent rate performance.

[0062] According to an embodiment of the present invention, the cell volume of the solid electrolyte material is larger than that of LiTi2(PO4)3. For example Thus, the lithium-ion transport channels are broadened, which can improve the ionic conductivity of solid electrolyte materials, resulting in batteries containing them having excellent rate performance.

[0063] According to an embodiment of the present invention, in the X-ray diffraction pattern of the solid electrolyte material, there is a diffraction peak (721) at a diffraction angle 2θ of 27.7°-27.8°, the peak intensity of the diffraction peak (721) is I1, the peak intensity of the diffraction peak (113) is I2, and 0.1≤I1 / I2≤0.5, for example, I1 / I2 can be 0.1, 0.2, 0.3, 0.4, 0.5, etc. Specifically, diffraction peak (721) is the diffraction peak of pyrophosphate, and diffraction peak (113) is the diffraction peak of LiTi2(PO4)3. The peak intensity ratio of the two is controlled within the above range. Pyrophosphate is introduced into the unit cell of LiTi2(PO4)3 structure, and the pyrophosphate content in the solid electrolyte material is moderate. The crystal cell parameters and unit cell volume of the solid electrolyte material are increased. This is because compared with phosphate, pyrophosphate ions have more electrons outside the nucleus and larger ionic radius. Therefore, through pyrophosphate recombination, the unit cell parameters of the solid electrolyte are increased. As a result, the lithium ion transport channel is widened, which can improve the ionic conductivity of the solid electrolyte material, so that the battery containing it has excellent rate performance.

[0064] According to embodiments of the present invention, the lattice distortion range of the solid electrolyte material is 0.05%-0.5%, for example, it can be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc. This widens the lithium-ion transport channels, improving the ionic conductivity of the solid electrolyte material and resulting in batteries containing it exhibiting excellent rate performance.

[0065] According to an embodiment of the present invention, the ionic conductivity of the solid electrolyte material is greater than or equal to 5 × 10⁻⁶. -4 S / cm, for example 5×10 -4 S / cm, 1×10 -4 S / cm, 5×10 -3 S / cm, 1×10 -3 S / cm, 5×10 -2 S / cm, 1×10 -2 S / cm, 5×10 -1 S / cm, 0.1S / cm, 1S / cm, 10S / cm, 100S / cm, etc., according to other embodiments of the present invention, the ionic conductivity of the solid electrolyte material is greater than or equal to 1×10⁻⁶. -3 S / cm, the ionic conductivity of solid electrolyte materials is within the above range. The high ionic conductivity of solid electrolyte materials is beneficial to the rapid transport of lithium ions, which makes batteries containing them have excellent rate performance.

[0066] According to embodiments of the present invention, the average particle size of the solid electrolyte material is 0.05 μm-0.5 μm, for example, 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, etc. According to other embodiments of the present invention, the average particle size of the solid electrolyte material is 0.05 μm-0.1 μm. Controlling the average particle size of the solid electrolyte material within the above range can reduce the obstruction of lithium-ion transport caused by excessively small particle size, and also avoid the extension of lithium-ion transport path caused by excessively large particle size of the solid electrolyte material, thereby improving the lithium-ion transport speed and thus improving the rate performance of the battery.

[0067] According to an embodiment of the present invention, at 25°C, the pH value of the solid electrolyte material is 6-10, for example, 6, 7, 8, 9, 10, etc. Limiting the pH value of the solid electrolyte material to this range can reduce gas production caused by excessive acidity of the solid electrolyte. It can also improve the structural stability of the solid electrolyte material, reduce the impact of structural instability on ionic conductivity, and simultaneously ensure sufficient lithium content within the solid electrolyte material, thereby improving its purity and ionic conductivity.

[0068] According to an embodiment of the present invention, the solid electrolyte material comprises:

[0069] Li x M 1 y M 2 z Ti u (PO4) v1 (P2O7) v2 ,

[0070] Among them, M 1 Including at least one of the first main group elements other than Li, M 2 Includes at least one of the metallic elements with a positive trivalent valence, 1 ≤ x < 4, 0.1 ≤ y ≤ 0.5, 0.2 <z≤0.5,1<u≤5.5,2≤v1≤6,0.1<v2≤3。

[0071] As an example, x can be 1, 2, 3, 3.5, 3.9, etc.; y can be 0.1, 0.2, 0.3, 0.4, 0.5, etc.; z can be 0.2, 0.3, 0.4, 0.5, etc.; u can be 1.1, 2, 3, 4, 5, 5.5, etc.; v1 can be 2, 3, 4, 5, 6, etc.; v2 can be 0.11, 0.5, 1, 2, 3, etc. According to other embodiments of the present invention, M... 1 Includes at least one of K, Rb, and Cs; M 2 It includes at least one of V, La and Cr.

[0072] Therefore, pyrophosphate ions were introduced into the unit cell of the LiTi2(PO4)3 structure, and the v2 value was controlled, and element M was introduced. 1 and M 2 And control the y and z values, M 1 It can enter lithium vacancies in the crystal lattice and modulate lattice defects in solid electrolytes, M 2 The large atomic radius of the ions, combined with the pyrophosphate group, can further broaden the lithium-ion transport channels. In summary, solid electrolyte materials using the above-mentioned structure have further improved ionic conductivity, which is more conducive to the rapid transport of lithium ions and improves the rate performance of batteries containing them.

[0073] Solid electrolyte materials have both phosphate and pyrophosphate groups as a framework, which can increase the cell size of the solid electrolyte, reduce the binding of charge carriers, and thus improve the ionic conductivity of the solid electrolyte material and improve the rate performance of the battery.

[0074] In a second aspect, the present invention provides a method for preparing the above-described solid electrolyte material. According to an embodiment of the present invention, the method includes:

[0075] S100: M 2 Source, Ti source, PO4 3- Source, P2O7 4- The precursor is obtained by mixing the source, precipitant, and solvent, followed by co-precipitation and filtration.

[0076] According to an embodiment of the present invention, the M 2 Source, Ti source, PO4 3- Source, P2O7 4- The source, precipitant, and solvent can be commercially available products.

[0077] As an example, the M 2 Sources include those containing M 2 oxides containing M 2 Phosphates containing M 2 sulfates, containing M 2 Chlorides, containing M 2 nitrates and containing M 2 At least one of the carbonates.

[0078] The Ti source includes at least one of the following: Ti-containing phosphate, Ti-containing acetate, Ti-containing sulfate, Ti-containing chloride, Ti-containing nitrate, and Ti-containing carbonate.

[0079] The PO4 3-The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4.

[0080] The P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7.

[0081] The precipitant includes at least one of sodium hydroxide, sodium carbonate, and ammonia.

[0082] According to an embodiment of the present invention, the solvent includes at least one of pure water, alcohols, and ethers.

[0083] S200: Combine the precursor with the Li source and M... 1 The source is mixed and sintered in an oxygen-containing atmosphere to obtain a solid electrolyte material.

[0084] According to an embodiment of the present invention, the M 1 Source and Li source can be commercially available products.

[0085] As an example, the M 1 Sources include those containing M 1 oxides containing M 1 Phosphates containing M 1 sulfates, containing M 1 Chlorides, containing M 1 nitrates and containing M 1 At least one of the carbonates.

[0086] The Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate.

[0087] According to an embodiment of the present invention, the oxygen-containing atmosphere includes oxygen or air.

[0088] According to an embodiment of the present invention, the sintering temperature is 600℃-800℃, and the sintering time is 4h-10h. For example, the sintering temperature can be 600℃, 650℃, 700℃, 750℃, 800℃, etc.; the sintering time can be 4h, 5h, 7h, 9h, 10h, etc. By controlling the sintering temperature and time within the above range, a solid electrolyte material with high purity and stable structure can be formed, thereby maintaining a high ionic conductivity.

[0089] In a third aspect of the invention, the present invention provides a positive electrode active material comprising a substrate and a coating layer disposed on at least a portion of the surface of the substrate, the coating layer comprising the solid electrolyte material described in the first aspect of the invention or a solid electrolyte material prepared by the method described in the second aspect.

[0090] Therefore, a solid electrolyte material is coated on the surface of the positive electrode active material. The solid electrolyte material introduces pyrophosphate groups into the unit cell of the conventional LiTi2(PO4)3 structure, and the doping element M... 1 and M 2 This increases the cell parameters and cell volume, thereby widening the lithium-ion transport channels. Coating the surface of the positive electrode active material with the aforementioned solid electrolyte material can improve the insertion and extraction rate of lithium ions in the positive electrode active material, increase the ionic conductivity of the positive electrode active material, and enable the battery containing it to have excellent rate performance.

[0091] Furthermore, the higher ionic conductivity of this solid electrolyte material accelerates the lithium-ion transport rate at the cathode-electrolyte interface, improving the capacity and rate performance of the cathode active material. Simultaneously, because pyrophosphate has an oxygen vacancy compared to phosphate, when oxygen evolution occurs in the cathode active material matrix due to anion-mediated reactions, the pyrophosphate in the coating layer can anchor the reactive oxygen to generate phosphate, thus maintaining the stability of the cathode active material's surface structure and improving cycle retention. At the same time, it reduces the strong oxidizing properties of the cathode active material in the charged state, decreasing battery gas production.

[0092] According to an embodiment of the present invention, the thickness of the coating layer is 10nm-500nm. For example, the thickness of the coating layer can be 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, etc. Thus, by controlling the thickness of the coating layer within the above range, it is possible to reduce the insignificant increase in the ionic conductivity of the positive electrode active material caused by an excessively low coating layer thickness, and also to reduce the obstruction of lithium-ion transport caused by an excessively high coating layer thickness. This results in high ionic conductivity of the positive electrode active material, and the battery containing it has excellent rate performance.

[0093] According to an embodiment of the present invention, based on the total mass of the positive electrode active material, the mass percentage of the solid electrolyte material is 0.01%-1%. For example, the mass percentage of the solid electrolyte material can be 0.01%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, etc. Controlling the mass percentage of the solid electrolyte material within the above range allows a coating layer of suitable thickness to be formed on the surface of the substrate, resulting in high ionic conductivity of the positive electrode active material and excellent rate performance of the battery containing it.

[0094] According to an embodiment of the present invention, in the DSC test curve of the positive electrode active material, the temperature corresponding to the exothermic peak is ≥220℃. For example, it can be 220℃, 230℃, 250℃, 300℃, 400℃, etc.

[0095] According to an embodiment of the present invention, the matrix includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate. As a result, the prepared positive electrode active material has high ionic conductivity, which makes the battery containing it have excellent rate performance.

[0096] According to an embodiment of the present invention, the gas production of the pouch cell assembled with the positive electrode active material is ≤2 mL / Ah after storage at 60°C for 7 days. It is evident that the battery of the embodiment of the present invention produces less gas.

[0097] In a fourth aspect, the present invention provides a method for preparing the positive electrode active material described in the third aspect, comprising:

[0098] S1: Grind the solid electrolyte material into nanoparticles and mix them with the matrix to obtain a mixture;

[0099] S2: The mixture is heat-treated in an oxygen-containing atmosphere to obtain a positive electrode active material.

[0100] Thus, the prepared positive electrode active material includes a substrate and a coating layer disposed on at least a portion of the surface of the substrate, the coating layer comprising the solid electrolyte material described in the first aspect of the present invention or a solid electrolyte material prepared by the method described in the second aspect. Thus, the surface of the positive electrode active material is coated with a solid electrolyte material, the solid electrolyte material introducing pyrophosphate ions into the unit cell of a conventional LiTi2(PO4)3 structure, and doped with element M. 1 and M 2 This increases the cell parameters and cell volume, thereby widening the lithium-ion transport channels and improving the ionic conductivity of solid electrolyte materials, resulting in batteries containing them having excellent rate performance.

[0101] According to an embodiment of the present invention, the oxygen-containing atmosphere includes oxygen or air.

[0102] Heat treatment can improve the adhesion of nanoparticle solid electrolyte materials to the surface of the substrate. According to embodiments of the present invention, the heat treatment temperature is 300℃-500℃, and the heat treatment time is 2h-8h. For example, the heat treatment temperature can be 300℃, 350℃, 400℃, 450℃, 500℃, etc., and the heat treatment time can be 2h, 4h, 5h, 7h, 8h, etc., within the above temperature and time ranges. This facilitates better adhesion of nanoparticle solid electrolyte materials to the surface of the substrate, improves the ionic conductivity of the positive electrode active material, and reduces gas generation in batteries containing it, thereby improving the capacity and rate performance of the positive electrode active material.

[0103] In a fifth aspect, the present invention provides a positive electrode sheet. According to embodiments of the present invention, the positive electrode sheet comprises the positive active material described in the third aspect of the present invention, or the positive active material prepared using the method described in the fourth aspect.

[0104] According to an embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes the aforementioned positive active material. The positive current collector can be a metal foil or a composite current collector (a metal material can be disposed on a polymer substrate to form a composite current collector). For example, the positive current collector can be an aluminum foil.

[0105] According to some embodiments of the present invention, the positive electrode active material layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, or fluorinated acrylate resin.

[0106] According to some embodiments of the present invention, the positive electrode active material layer may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0107] According to some embodiments of the present invention, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0108] It should be noted that the features and advantages described above for the positive electrode active material and its preparation method also apply to this positive electrode sheet, and will not be repeated here.

[0109] In a sixth aspect, the present invention provides a battery. According to an embodiment of the present invention, the battery includes at least one of the solid electrolyte material described in the first aspect, the solid electrolyte material prepared by the method described in the second aspect, and the positive electrode sheet described in the fifth aspect.

[0110] As an example, a battery includes a positive electrode, a negative electrode, an electrolyte, and a separator, with the separator located between the positive and negative electrodes. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0111] According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material. The negative electrode current collector can be a metal foil or a composite current collector (a metal material can be disposed on a polymer substrate to form a composite current collector). For example, the positive electrode current collector can be a copper foil.

[0112] According to some embodiments of the present invention, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0113] According to some embodiments of the present invention, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0114] According to some embodiments of the present invention, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0115] According to some embodiments of the present invention, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, and binder, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing, and other processes.

[0116] According to some embodiments of the present invention, the negative electrode sheet may include a lithium metal sheet or a lithium alloy, such as a lithium indium alloy.

[0117] According to further embodiments of the present invention, the type of separator is not particularly limited, and any known porous separator with good chemical and mechanical stability can be selected. As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0118] According to further embodiments of the present invention, there is no specific limitation on the type of electrolyte, which can be selected according to requirements. For example, the electrolyte can be in a gel state or a completely solid state. According to some specific embodiments of the present invention, the electrolyte is an electrolyte solution comprising a lithium salt and a solvent.

[0119] According to some specific embodiments of the present invention, the lithium salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, or lithium tetrafluorooxalate phosphate.

[0120] According to some specific embodiments of the present invention, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethylene glycol dimethyl ether, methyl ethyl sulfone, or diethyl sulfone.

[0121] In some embodiments of this application, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0122] It should be noted that the features and advantages described above for the positive electrode also apply to this solid-state battery, and will not be repeated here.

[0123] In a seventh aspect, the present invention provides an electrical device. According to an embodiment of the invention, the electrical device includes the battery described above. According to an embodiment of the invention, the electrical device may include, but is not limited to, mobile phones, laptops, electric vehicles, etc.

[0124] It should be noted that the features and advantages described above for the battery also apply to this electrical device, and will not be repeated here.

[0125] The following describes embodiments of the present invention. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0126] Example 1

[0127] Preparation of solid electrolyte materials:

[0128] Vanadium oxide, titanium oxysulfate, disodium hydrogen phosphate, and titanium pyrophosphate were mixed in a molar ratio V 3+ :Ti 4+ :PO4 3- P2O7 4- The precursor was mixed in pure water in a ratio of 0.3:2.7:4:0.5, sodium hydroxide was added as a precipitant, and the mixture was heated to 60°C and stirred for 30 minutes to form a uniform precipitate. After filtration and drying, the precursor powder was obtained.

[0129] The precursor, lithium carbonate, and potassium carbonate were combined according to Li... + :K + :PO4 3- The mixture was weighed in a ratio of 2:0.3:4 and mixed evenly in a high-speed mixer. It was then sintered in air at 700°C for 8 hours to obtain a micron-sized solid electrolyte material with an average particle size of 20 microns. The pH value of the solid electrolyte material was 6.5 at 25°C.

[0130] A slurry with a 50% solid content was prepared by adding micron-sized composite oxide solid electrolyte material to pure water. This slurry was then ball-milled with zirconia for 6 hours to obtain a nano-slurry with an average particle size of less than 200 nm. After spray drying, the resulting powder was further processed by dissociation and sieving to obtain a powder with a relatively uniform particle size distribution and a Li₂K₂ composition. 0.3 V 0.3 Ti 2.7 (PO4)4(P2O7) 0.5 Solid electrolyte nanoparticles.

[0131] Preparation of positive electrode active materials:

[0132] The obtained solid electrolyte nanoparticles and LiNi 0.9 Co 0.05 Mn 0.05 The matrix of the positive electrode active material of O2 is weighed at a mass ratio of 0.1:100 and mixed evenly in a high-speed mixer. It is then heat-treated at 400°C for 6 hours in an air atmosphere to obtain a positive electrode active material coated with solid electrolyte.

[0133] The preparation methods of Examples 2-15 and Comparative Examples 1-4 are the same as those of Example 1, with the differences detailed in Table 1.

[0134] Table 1

[0135] Preparation method of coin cell battery: The positive electrode active material, solid electrolyte material, acetylene black and polyvinylidene fluoride (PVDF) prepared in each embodiment are mixed in a mass ratio of 90:2:3:5, coated on aluminum foil and dried. The mixture is then pressed into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm under a pressure of 100 MPa. The positive electrode sheet is then dried in a vacuum drying oven at 120°C for 12 h. The negative electrode uses a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator uses a Celgard 2400 porous membrane with a thickness of 25 μm; the electrolyte uses a 1 mol / L mixture of equal parts LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC). The positive electrode sheet, separator, negative electrode sheet, and 4 μL of electrolyte are assembled into a 2025 type coin cell in an Ar gas glove box with a water content and oxygen content of less than 5 ppm.

[0136] Performance testing methods

[0137] 1. Test method for ionic conductivity of solid electrolyte materials

[0138] The method for testing ionic conductivity is to press 5 mg of solid electrolyte material nanopowder into a sheet-like sample under a pressure of 200 MPa in a steel mold with a diameter of 12 mm, and then place the formed sheet-like sample in a fixture to perform AC impedance testing on an electrochemical workstation to obtain the ionic conductivity.

[0139] 2. XRD Testing Method

[0140] The X-ray diffraction test method is to use an automatic X-ray diffractometer to analyze the phase and crystal structure. The working voltage is 40kV, the working current is 250mA, and continuous scanning is used. The scanning speed is 4° / min, the step size is 0.02°, and the scanning angle is 10°-80°.

[0141] The XRD patterns of the solid electrolyte materials of Examples 1-4 and Comparative Example 1 are shown in Figures 1 and 2. It can be seen that, compared with Comparative Example 1, the 2θ value of the diffraction peak representing LiTi2(PO4)3 in the solid electrolyte materials of Examples 1-4 is reduced compared with the 2θ value of the corresponding diffraction peak in the standard spectrum of LiTi2(PO4)3. The reduction angle is between 0.02° and 0.06°.

[0142] The scanning electron microscope image of the solid electrolyte material in Example 1 is shown in Figure 3. It can be seen that the solid electrolyte material is nanoscale with an average particle size of about 200 nm.

[0143] 3. Battery Rate Performance Test Method

[0144] The assembled batteries were tested at 0.1C and 1C rates, and the ratio of capacity at 1C rate to capacity at 0.1C rate was calculated. The test results are shown in Table 2.

[0145] Table 2

[0146] As shown in Table 2, in Examples 1-15 of this application, the 2θ value of the diffraction peak representing LiTi2(PO4)3 in the X-ray diffraction patterns of the solid electrolyte materials is reduced by 0.02°-0.06° compared to the corresponding 2θ value in the standard pattern of LiTi2(PO4)3. However, the reduction in 2θ value in Comparative Examples 1-4 is not within the 0.02°-0.06° range, and the ionic conductivity and rate performance of the solid electrolyte materials in Comparative Examples 1-4 are significantly lower than those in Examples 1-15 of this application. Therefore, this application, by controlling the 2θ value of the diffraction peak representing LiTi2(PO4)3 in the X-ray diffraction patterns of the solid electrolyte materials to be reduced by 0.02°-0.06° compared to the corresponding 2θ value in the standard pattern of LiTi2(PO4)3, broadens the lithium-ion transport channel, thereby improving the ionic conductivity of the solid electrolyte material and resulting in batteries containing it exhibiting excellent rate performance.

[0147] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0148] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A solid electrolyte material, wherein, The solid electrolyte material has a NASICON crystal structure. In the X-ray diffraction pattern of the solid electrolyte material, the 2θ value of the diffraction peak representing LiTi2(PO4)3 is reduced by 0.02°-0.06° compared with the 2θ value of the corresponding diffraction peak in the standard pattern of LiTi2(PO4)3.

2. The solid electrolyte material according to claim 1, wherein, The diffraction peaks representing LiTi2(PO4)3 include diffraction peak (012), diffraction peak (104), diffraction peak (113) and diffraction peak (024); Optionally, the a value of the solid electrolyte material is increased compared to that of LiTi2(PO4)3. The c value increases Optionally, the cell volume of the solid electrolyte material is larger than that of LiTi2(PO4)3. Optionally, in the X-ray diffraction pattern of the solid electrolyte material, there is a diffraction peak (721) at a diffraction angle 2θ of 27.7°-27.8°, the peak intensity of the diffraction peak (721) is I1, the peak intensity of the diffraction peak (113) is I2, and 0.1≤I1 / I2≤0.

5.

3. The solid electrolyte material according to claim 1, wherein, The ionic conductivity of the solid electrolyte material is greater than or equal to 5 × 10⁻⁶. -4 S / cm, can be greater than or equal to 1×10 -3 S / cm; Optionally, the average particle size of the solid electrolyte material is 0.05 μm-0.5 μm, preferably 0.05 μm-0.1 μm; Optionally, at 25°C, the pH value of the solid electrolyte material is 6-10.

4. The solid electrolyte material according to any one of claims 1-3, wherein, The solid electrolyte material includes: Li x M 1 y M 2 z Ti u (PO4) v1 (P2O7) v2 , Among them, M 1 Including at least one of the first main group elements other than Li, M 2 Includes at least one of the metallic elements with a positive trivalent valence, 1 ≤ x < 4, 0.1 ≤ y ≤ 0.5, 0.2 <z≤0.5,1<u≤5.5,2≤v1≤6,0.1<v2≤3。 5. The solid electrolyte material according to claim 4, wherein, M 1 Includes at least one of K, Rb, and Cs; Optional, M 2 It includes at least one of V, La and Cr.

6. A method for preparing the solid electrolyte material according to any one of claims 1-5, wherein, include: M 2 Source, Ti source, PO4 3- Source, P2O7 4- The source, precipitant, and solvent are mixed, and the precursor is obtained by co-precipitation and filtration. The precursor is combined with the Li source and M 1 The source is mixed and sintered in an oxygen-containing atmosphere to obtain a solid electrolyte material.

7. The method according to claim 6, wherein, The oxygen-containing atmosphere includes oxygen or air; Optionally, the sintering temperature is 600℃-800℃, and the sintering time is 4h-10h; Optionally, the M 1 Sources include those containing M 1 oxides containing M 1 Phosphates containing M 1 sulfates, containing M 1 Chlorides, containing M 1 nitrates and containing M 1 At least one of the carbonates; Optionally, the M 2 Sources include those containing M 2 oxides containing M 2 Phosphates containing M 2 sulfates, containing M 2 Chlorides, containing M 2 nitrates and containing M 2 At least one of the carbonates; Optionally, the Ti source includes at least one of Ti-containing phosphates, Ti-containing acetates, Ti-containing sulfates, Ti-containing chlorides, Ti-containing nitrates, and Ti-containing carbonates; Optionally, the PO4 3- The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4; Optionally, the Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate; Optionally, the P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7; Optionally, the precipitant includes at least one of sodium hydroxide, sodium carbonate, and ammonia.

8. A positive electrode active material, wherein, It includes a substrate and a coating layer disposed on at least a portion of the surface of the substrate, the coating layer comprising a solid electrolyte material according to any one of claims 1-5 or a solid electrolyte material prepared by the method described in claim 6 or 7.

9. The positive electrode active material according to claim 8, wherein, The thickness of the coating layer is 10nm-500nm; Optionally, based on the total mass of the positive electrode active material, the mass percentage of the solid electrolyte material is 0.01%-1%; Optionally, in the DSC test curve of the positive electrode active material, the temperature corresponding to the exothermic peak is ≥220℃; Optionally, the matrix includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate.

10. A method for preparing the positive electrode active material according to claim 8 or 9, wherein, include: Solid electrolyte materials are ground into nanoparticles and mixed with a matrix to obtain a mixture. The mixture is heat-treated in an oxygen-containing atmosphere to obtain a positive electrode active material.

11. The method according to claim 10, wherein, The oxygen-containing atmosphere includes oxygen or air; Optionally, the heat treatment temperature is 300℃-500℃, and the heat treatment time is 2h-8h.

12. A positive electrode plate, wherein, Includes the positive electrode active material as described in claim 8 or 9, or the positive electrode active material prepared by the method described in claim 10 or 11.

13. A battery, wherein, It includes at least one of the solid electrolyte materials according to any one of claims 1-5, the solid electrolyte materials prepared by the method of claim 6 or 7, and the positive electrode sheet according to claim 12.

14. An electrical appliance, wherein, Includes the battery as described in claim 13.

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