Material for battery positive electrode, positive electrode plate as well as preparation method and application of positive electrode plate

Abstract

The invention belongs to the technical field of battery materials and preparation thereof, and relates to a material for a battery positive electrode, a positive electrode plate and a preparation method and application thereof. In order to solve the technical problems that in the prior art, residues on the surface of a positive electrode material generate side reaction, and in the charging and discharging process of primary particles, due to anisotropy and volume expansion, the material generates cracks, and transition metal ions in the material are dissolved, the invention provides the material for the battery positive electrode. The core body, the first shell layer and the second shell layer are sequentially arranged from inside to outside; the core body comprises the following components in parts by mass: 40-50 parts of positive electrode powder and 30-40 parts of a solvent; the surface of the core body is coated with the first shell layer, the first shell layer comprises 5-7 parts of a carbon source material, and the carbon source material is taken from saccharides; the surface of the first shell layer is coated with the second shell layer, and the second shell layer comprises 3-5 parts of nano solid electrolyte powder and 5-15 parts of a solvent.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials and their preparation, and specifically relates to materials for battery cathodes, cathode plates, and their preparation methods and applications. Background Art

[0002] The lithium-ion battery industry has developed rapidly in recent years, and the requirements for the energy density of power batteries have been gradually increasing. However, the energy density of current lithium-ion batteries has basically reached the theoretical limit of their materials, and it has encountered a large bottleneck in further improvement. The NCM ternary layered cathode material with high specific capacity and low cost is one of the research hotspots in the cathode material family and is considered to be a lithium-ion power battery cathode material with great application prospects. However, it also has defects such as low capacity retention rate and poor thermal stability. In the actual application process, the ternary cathode material faces the following problems: Ni 2 + and Li+ will undergo the mixing phenomenon of Li+ / Ni 2 +, which will further lead to the transformation of the material structure; the residual alkali on the material surface will react with the lithium salt in the electrolyte, which will further cause safety problems of the battery; during the charge and discharge process of the primary particles in the material, due to anisotropy and volume expansion, cracks will be generated in the material, which will further cause the dissolution of transition metal ions in the material. Among them, the mixing of Li+ / Ni 2 + is because the radius of divalent nickel ions is slightly smaller than that of lithium ions, the thickness of the main wafer will increase because lithium ions enter the transition metal layer, and it will be affected by the electric field of surrounding transition metal elements, and its diffusion barrier increases sharply, so that some lithium ions cannot be effectively deintercalated and inactivated during the charge and discharge process of the material. These factors have always been important factors affecting the cycle performance of ternary materials. In addition, the layered structure of the NCM ternary cathode material is prone to the Jahn-Teller effect, which will further cause local phase transformation of the material and lead to serious irreversible attenuation of the material capacity.

[0003] For example, the Chinese patent application publication number CN108987683A, the application date is May 30, 2018, and the name is "A method for preparing a carbon-coated ternary positive electrode material". The disclosed method includes: adding a ternary positive electrode material and a silica precursor to an organic solvent, mixing them evenly, then dripping deionized water, stirring to react, then evaporating all the solvents, and calcining to obtain a silica-coated ternary positive electrode material; adding the silica-coated ternary positive electrode material and an organic carbon source to a dispersant to obtain a suspension, evaporating and sintering to obtain a silica-carbon double-coated ternary positive electrode material; soaking the silica-carbon double-coated ternary positive electrode material in an alkaline solution to obtain a carbon-coated ternary positive electrode material. Doping and surface coating modification are considered to be the main methods to effectively reduce side reactions and improve material structural stability, electrochemical performance and thermal stability. However, although conventional transition metal oxide coating can significantly improve the performance of ternary positive electrode materials, the coating also inhibits ion diffusion, and the coated oxides are mostly semiconductors with poor conductivity, the diffusion kinetic resistance of lithium ions becomes larger, which will cause the material capacity to decrease, which is not good for the material capacity and long-term cycle life.

[0004] In the existing lithium-ion battery system, the high-nickel ternary cathode system has become the preferred material for major lithium battery companies. However, due to the anisotropic volume change of the high-nickel ternary material, microcracks are easily generated inside. The cracks increase the contact area between the electrode active material and the electrolyte, increase the degree of side reactions, and generate an electrochemically inactive passivation layer on the surface of the microcracks, which increases the battery impedance and reduces the electrochemical performance. In addition, when the high-nickel ternary cathode material comes into contact with air, the residual lithium on the surface of the material will react with the air to form LiOH, Li 2 CO 2 As a result of the production of by-products such as nickel, the application of high-nickel ternary materials is still in the experimental stage. Summary of the invention

[0005] 1. Technical problem to be solved by the invention

[0006] In view of the technical problems in the prior art that the residue on the surface of the positive electrode material produces side reactions, and the primary particles produce cracks in the material due to anisotropy and volume expansion during the charge and discharge process, which causes the dissolution of transition metal ions in the material, the present application provides a battery positive electrode material and a preparation method thereof;

[0007] Furthermore, the present invention also provides a positive electrode plate;

[0008] At the same time, the invention also provides a lithium battery.

[0009] 2. Technical solution

[0010] In order to achieve the above purpose, the technical solution provided is:

[0011] Based on the object of the present invention, a first aspect of the present invention provides a material for a battery positive electrode, comprising a core body, a first shell layer and a second shell layer arranged in sequence from the inside to the outside; calculated by mass parts,

[0012] The core body comprises 40-50 parts of positive electrode powder and 30-40 parts of solvent. On this basis, the ratio of the positive electrode powder to the solvent can be further preferably 45-50 parts of positive electrode powder and 35-40 parts of solvent;

[0013] The first shell layer coats the surface of the core body. The first shell layer comprises 5-7 parts of carbon source material, and the carbon source material is taken from saccharides. For example, it can be 5 parts, 5.5 parts, 6 parts, 6.5 parts or 7 parts;

[0014] The second shell layer coats the surface of the first shell layer. The second shell layer comprises 3-5 parts of nano solid electrolyte powder and 5-15 parts of solvent. For example, 3 parts of nano solid electrolyte powder and 5 parts of solvent; or 4 parts of nano solid electrolyte powder and 10 parts of solvent; or 5 parts of nano solid electrolyte powder and 15 parts of solvent.

[0015] For the material for a battery positive electrode according to any one of the embodiments of the first aspect of the present invention, the positive electrode powder is any one of polycrystalline high-nickel ternary positive electrode powder, lithium cobaltate positive electrode powder, lithium manganate positive electrode powder, and lithium iron phosphate positive electrode powder.

[0016] Diverse selections bring various beneficial effects, including high energy density, excellent cycle stability, improved safety, improved rate performance and improved Coulomb efficiency. Specifically, polycrystalline high-nickel ternary positive electrode powder provides high specific capacity and energy density, lithium cobaltate positive electrode powder ensures high voltage platform and cycle stability, lithium manganate positive electrode powder realizes high rate performance and high temperature stability, while lithium iron phosphate positive electrode powder provides long cycle life and good thermal stability. Through the coating of carbon source material and nano solid electrolyte powder, the conductivity and ionic conductivity of these materials are further improved, side reactions are reduced, and the overall performance and safety of the battery are improved.

[0017] For the material for a battery positive electrode according to any one of the embodiments of the first aspect of the present invention, the carbon source material is any one of glucose powder or fructose powder.

[0018] The carbon source material is glucose powder or fructose powder, which improves the conductivity and structural stability of the material, reduces the structural damage of the material during charge and discharge, and thus significantly improves the electrochemical performance and cycle life of the battery. As natural organic carbon sources, glucose and fructose not only have low cost and wide sources, but also the carbon layer formed by carbonization at high temperature can effectively coat the positive electrode material, enhance its conductivity, reduce side reactions, and improve the safety and Coulomb efficiency of the battery.

[0019] The material for the positive electrode of a battery according to any embodiment of the first aspect of the present invention, wherein the nano solid electrolyte powder is any one of LTPSO powder, LATP powder, LLZO powder, and LLTO powder.

[0020] LTPSO, LATP, LLZO, and LLTO powders all have high ionic conductivity, which can effectively improve the charge and discharge efficiency of the battery. At the same time, the chemical stability and mechanical properties of these materials are excellent, significantly enhancing the cycle stability and safety of the battery, reducing side reactions during charge and discharge, extending the service life of the battery, and thus showing broad application prospects in the field of high-performance lithium-ion batteries.

[0021] The material for the positive electrode of a battery according to any embodiment of the first aspect of the present invention, wherein the particle size of the nano solid electrolyte powder is 100 nm to 170 nm. For example, it can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm.

[0022] A smaller particle size shortens the ion migration path, reduces the resistance of ion migration, and thus significantly improves the ionic conductivity. A smaller particle size provides a greater sintering driving force, which is beneficial to the sintering process. Smaller particles can reach densification faster during the sintering process, improving the sintering efficiency, and can achieve a higher density at a lower sintering temperature and a shorter holding time. A smaller particle size helps to shorten the diffusion path of lithium ions in the material, reduce the diffusion resistance, and thus improve the charge and discharge rate and rate performance of the battery. At the same time, the solid electrolyte formed by the small particle size material has better cycle stability, which can reduce the concentration gradient and mechanical stress generated during the diffusion of lithium ions, and is beneficial to extending the cycle life of the battery. The small particle size material helps to form a more intimate interfacial contact, reduce the interfacial resistance between the solid electrolyte and the electrode, and improve the overall performance of the battery.

[0023] The material for the positive electrode of a battery according to any embodiment of the first aspect of the present invention, wherein the solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide, and deionized water.

[0024] Both NMP and DMF are highly polar aprotic solvents with good solubility and chemical stability. They can effectively dissolve the active substances and binders in the cathode material, thereby improving the stability and uniformity of the slurry. NMP has good wettability and fluidity, enabling the mixture to be evenly coated on the moving cathode aluminum foil substrate, reducing coating defects and non-uniformity. DMF also has good solubility and fluidity, which can improve the coating performance of the slurry. During the baking stage, NMP and DMF can volatilize at a stable rate, forming a porous microelectrode structure with uniform pore size and distribution, which helps to improve the electrochemical performance and cycle stability of the battery. Deionized water as a solvent has the advantages of low cost and environmental friendliness, but the evaporation rate of water needs to be controlled during baking to avoid coating cracking. The use of NMP and DMF can reduce the resistance of the cathode electrode sheet and improve the rate performance and charge-discharge efficiency of the battery.

[0025] Based on the purpose of the present invention, a second aspect of the present invention provides a preparation method for a material for a battery cathode, comprising the steps of:

[0026] S1. Mix 40 - 50 parts of cathode powder and 30 - 40 parts of solvent, and ball-mill and disperse evenly to obtain a core body;

[0027] S2. Add 5 - 7 parts of carbon source material, which is taken from sugars, to the core body, and ball-mill and disperse evenly to obtain a material coated with a first shell layer;

[0028] S3. Remove bubbles and dry. After removing bubbles from the material coated with the first shell layer by sieving, spray-dry to obtain a dried material;

[0029] S4. Mix 3 - 5 parts of nano solid electrolyte powder with 5 - 15 parts of solvent and disperse evenly to obtain a second shell material;

[0030] S5. Spray the second shell material onto the surface of the dried material and sinter to obtain the material for the battery cathode.

[0031] Based on the purpose of the present invention, a third aspect of the present invention provides a cathode electrode sheet, comprising the material for the battery cathode as described above; further comprising a conductive agent, a binder, and aluminum foil.

[0032] Based on the purpose of the present invention, a fourth aspect of the present invention provides a lithium battery, wherein the lithium battery contains a cathode electrode sheet, and is characterized in that: the cathode electrode sheet contains the material for the battery cathode as described above; or,

[0033] the cathode electrode sheet contains the material for the battery cathode prepared by the method as described above; or,

[0034] the cathode electrode sheet is the cathode electrode sheet as described above.

[0035] The lithium battery according to any embodiment of the fourth aspect of the present invention stores 205 mAh of electricity per gram of battery material when charged and discharged at a rate of 1C within the voltage range of 2.8V to 4.3V. After 800 charge-discharge cycles, the capacity of the lithium battery is ≥ 90% of the initial capacity of the lithium battery.

[0036] Any embodiment of any aspect of the present invention can be combined with other embodiments without contradiction. In addition, in any embodiment of any aspect of the present invention, any technical feature can be applied to the corresponding technical feature in other embodiments without contradiction.

[0037] Without contradiction, any technical feature of any aspect of the present invention or any embodiment of that aspect is equally applicable to any other embodiment or any embodiment of any other aspect. Of course, when applicable to each other, the corresponding features can be appropriately modified if necessary. The following further describes the various aspects and features of the present invention.

[0038] 3. Beneficial effects

[0039] Adopting the technical solution provided by the present invention, compared with the existing well-known technologies, it has the following beneficial effects:

[0040] (1) The material used for the positive electrode of the battery of the present invention includes a core body, a first shell layer, and a second shell layer arranged in sequence from the inside to the outside. The first shell layer covers the surface of the core body and contains 5 to 7 parts of a carbon source material taken from sugars. The first shell layer can improve the conductivity of the positive electrode material (such as high-nickel ternary positive electrode material). The second shell layer covers the surface of the first shell layer and contains 3 to 5 parts of nano-solid electrolyte powder and 5 to 15 parts of solvent. The second shell layer (oxide electrolyte layer) can reduce the direct contact between the electrolyte and the positive electrode material (such as high-nickel ternary positive electrode material), and has a relatively high density. It can reduce the increase in specific surface area caused by cracks in the positive electrode material, thereby suppressing side reactions, better alleviating the lithium-nickel mixing in the material and the excess lithium on the material surface, reducing irreversible side reactions, reducing the formation of the positive electrode CEI film, and at the same time reducing material loss and gas generation. It can effectively improve the capacity performance and cycle stability of the positive electrode (such as high-nickel ternary). The core body contains 40 to 50 parts of positive electrode powder and 30 to 40 parts of solvent. When the positive electrode material is polycrystalline high-nickel ternary (Ni content ≥ 80%), the present application solves the problem that during the long cycle of the positive electrode, the stability of the grain boundaries is poor, and the continuous lithium deintercalation and intercalation process of the particles will cause the grain boundaries of the particles to deteriorate, eventually forming microcracks, resulting in hindered lithium deintercalation and intercalation.

[0041] (2) The preparation method of the cathode material for the battery of the present invention ensures uniform mixing of the cathode powder and the solvent through ball milling and dispersion to form a uniform core, providing a good foundation for subsequent coating. The carbon source material (such as glucose) is carbonized at high temperature to form a carbon layer, which can significantly improve the conductivity and structural stability of the material and reduce the structural damage during charge and discharge. Removing bubbles can ensure the uniformity and density of the material, and spray drying can quickly remove moisture, improve production efficiency, and reduce side reactions during the subsequent sintering process. The nano solid electrolyte powder can improve the ionic conductivity and interface stability of the material, reduce the internal resistance of the battery, and improve the electrochemical performance of the battery. Through spraying and sintering, the nano solid electrolyte powder is uniformly coated on the surface of the material to form a dense second shell layer, further improving the stability and electrochemical performance of the material.

[0042] (3) The positive electrode sheet and lithium battery of the present invention using the cathode material for the battery have a high energy density: when the battery material per gram is charged and discharged at a rate of 1C within the voltage range of 2.8V to 4.3V, the stored charge is 205mAh, thereby extending the usage time of the battery. After 800 charge and discharge cycles, the capacity of the lithium battery ≥ 90% of the initial capacity of the lithium battery. This indicates that the material has excellent cycle stability, can maintain a high capacity after multiple charge and discharges, and extends the service life of the battery. Description of the Drawings

[0043] Figure 1 It is the normal temperature cycle performance diagram of the corresponding single cell cores in Embodiments 1 - 3 and Comparative Examples 1 - 2 of the present invention.

[0044] Figure 2 It is the rate performance diagram of the corresponding single cell cores in Embodiments 1 - 3 and Comparative Examples 1 - 2 of the present invention. Detailed Embodiments

[0045] The present invention will be further described below in conjunction with specific embodiments.

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] Abbreviations

[0048] LTPSO, Low Temperature Polycrystalline Silicon Oxide, low temperature polycrystalline silicon oxide;

[0049] LATP, Lithium Aluminum Titanium Phosphate;

[0050] LLZO, Lithium Lanthanum Zirconate;

[0051] LLTO, Lithium Lanthanum Titanate;

[0052] Example 1

[0053] The material for the positive electrode of the battery in this example is composed of the following components: polycrystalline high-nickel ternary powder, glucose, LTPSO, and a solvent. The mass ratio of each component is: 40 parts of polycrystalline high-nickel ternary powder, 7 parts of glucose powder, 3 parts of nano-LTPSO powder, and 50 parts of solvent.

[0054] The diameter D50 of the nano-LTPSO particles is 100 nm.

[0055] The solvent is N-methylpyrrolidone.

[0056] The material for the positive electrode of the battery in this example includes the following preparation steps:

[0057] Step 1: Take 40 parts by mass of polycrystalline high-nickel ternary positive electrode powder and mix it with 40 parts by mass of the solvent, and disperse it evenly with a ball mill to obtain a core body;

[0058] Step 2: Add 7 parts by mass of glucose powder and disperse it evenly with a ball mill to obtain a material coated with the first shell layer;

[0059] Step 3: Sieve through a 100-mesh sieve to remove air bubbles to obtain a dried material;

[0060] Step 4: Spray-dry the dried material by spray drying;

[0061] Step 5: Mix 3 parts by mass of nano-LTPSO powder with 10 parts of solvent and disperse it evenly to obtain a second shell material;

[0062] Step 6: Spray the obtained liquid second shell material onto the surface of the dried material with a fluidized bed to obtain a high-nickel ternary positive electrode material with a double-layer coating;

[0063] Step 7: Sinter the prepared high-nickel ternary positive electrode material with a double-layer coating in a nitrogen atmosphere in a tubular furnace to obtain the material for the positive electrode of the battery.

[0064] Step 8: Use the obtained cathode material, conductive agent, PVDF binder, and aluminum foil to fabricate a cathode electrode sheet, and then fabricate a soft-pack lithium-ion battery with a graphite anode electrode sheet. Conduct cycle and rate performance tests on the battery.

[0065] The obtained results are shown in Tables 1 and 2.

[0066] Example 2

[0067] The cathode material for the battery in this example consists of the following components: polycrystalline high-nickel ternary powder, glucose, LTPSO, and a solvent. The mass ratio of each component is: 50 parts of polycrystalline high-nickel ternary powder, 5 parts of glucose powder, 5 parts of nano-LTPSO powder, and 40 parts of solvent.

[0068] The diameter D50 of the nano-LTPSO particles is 150 nm.

[0069] The solvent is N, N-dimethylformamide.

[0070] The cathode material for the battery in this example includes the following preparation steps:

[0071] Step 1: Take 50 parts by mass of polycrystalline high-nickel ternary cathode powder and mix it with 30 parts by mass of the solvent, and disperse it evenly with a ball mill to obtain a core body.

[0072] Step 2: Add 5 parts by mass of glucose powder and disperse it evenly with a ball mill to obtain a material coated with the first shell layer.

[0073] Step 3: Sieve through a 100-mesh sieve to remove air bubbles to obtain the dried material.

[0074] Step 4: Spray-dry the dried material using spray drying.

[0075] Step 5: Mix 5 parts by mass of nano-LTPSO powder with 10 parts of the solvent and disperse it evenly to obtain a second shell material.

[0076] Step 6: Spray the obtained liquid second shell material onto the surface of the high-nickel ternary cathode powder coated with glucose using a fluidized bed to obtain a double-coated high-nickel ternary cathode material.

[0077] Step 7: Sinter the prepared double-coated high-nickel ternary cathode material in a nitrogen atmosphere in a tube furnace to obtain the cathode material for the battery.

[0078] Step 8: Use the obtained cathode material, conductive agent, PVDF binder, and aluminum foil to fabricate a cathode electrode sheet, and then fabricate a soft-pack lithium-ion battery with a graphite anode electrode sheet. Conduct cycle and rate performance tests on the battery.

[0079] The obtained results are shown in Tables 1 and 2.

[0080] Example 3

[0081] The material for the positive electrode of the battery in this example is composed of the following components: LTPSO, polycrystalline high-nickel ternary powder, glucose, and a solvent. The mass ratio of each component is as follows: 45 parts of polycrystalline high-nickel ternary powder, 5 parts of nano LTPSO powder, 5 parts of glucose powder, and 45 parts of solvent.

[0082] The diameter D50 of the nano LTPSO particles is 170 nm.

[0083] The solvent is deionized water.

[0084] A double-layer coated core-shell structured high-nickel main material and its preparation method include the following preparation steps:

[0085] Step 1: Take 45 mass parts of polycrystalline high-nickel ternary positive electrode powder and mix it with 35 mass parts of solvent, and disperse it evenly with a ball mill to obtain a core body;

[0086] Step 2: Add 5 mass parts of glucose powder and disperse it evenly with a ball mill to obtain a material coated with the first shell layer;

[0087] Step 3: Sieve through a 100-mesh sieve to remove air bubbles to obtain a dried material;

[0088] Step 4: Spray-dry the dried material by spray drying;

[0089] Step 5: Mix 5 mass parts of nano LTPSO powder with 10 parts of solvent and disperse it evenly to obtain a second shell material;

[0090] Step 6: Spray the obtained liquid second shell material onto the surface of the dried material with a fluidized bed to obtain a double-layer coated ternary positive electrode material;

[0091] Step 7: Sinter the prepared double-layer coated high-nickel ternary positive electrode material in a nitrogen atmosphere in a tubular furnace to obtain the material for the positive electrode of the battery.

[0092] Step 8: Make the obtained material for the positive electrode of the battery into a positive electrode plate together with a conductive agent, a PVDF binder, and aluminum foil, and then make it into a soft-pack lithium-ion battery together with a graphite negative electrode plate, and perform cycle and rate performance tests on the battery.

[0093] Compared with the prior art, for the double-layer core-shell structured high-nickel ternary cathode material prepared in Examples 1-3, the carbon layer can improve the conductivity of the high-nickel ternary cathode material, the oxide electrolyte layer can reduce the direct contact between the electrolyte and the high-nickel ternary cathode material, and the coating layer has a relatively high density, which can reduce the specific surface area increase effect caused by cracks in the cathode material, thereby suppressing side reactions and reducing material loss and gas generation. After glucose is oxidized, there is a gap between the formed carbon layer and the oxide electrolyte layer, which can release the stress generated by the expansion of the high-nickel ternary cathode material and reduce the degree of fragmentation and pulverization of the high-nickel ternary cathode material.

[0094] The results obtained are shown in Tables 1 and 2.

[0095] Comparative Example 1

[0096] The cathode material of this comparative example is basically the same as that of Example 1, except that: nano-LTPSO is not used.

[0097] The results obtained are shown in Tables 1 and 2.

[0098] Comparative Example 2

[0099] The cathode material of this comparative example is basically the same as that of Example 1, except that: glucose is not used for carbon coating.

[0100] The results obtained are shown in Tables 1 and 2.

[0101] It can be seen from the examples and comparative examples that in Comparative Example 1, without using nano-LTPSO, the ionic conductivity of the cathode material may be relatively low. As a high-performance solid electrolyte, LTPSO can significantly improve the ionic conductivity of the material, thereby improving the charge and discharge efficiency of the battery. Without LTPSO, the ionic conductivity of the material may decrease, resulting in poor rate performance and cycle stability of the battery. LTPSO can form a dense second shell layer to improve the interfacial stability of the material and reduce side reactions. Without using LTPSO, the interfacial stability of the material may decrease, leading to more side reactions during the charge and discharge process of the battery, affecting the life and safety of the battery.

[0102] In Comparative Example 2, without using glucose for carbon coating, the conductivity of the cathode material decreases. The carbon layer formed by carbonizing glucose at high temperature can significantly improve the conductivity of the material, reduce the polarization phenomenon during the charge and discharge process of the material, and improve the discharge specific capacity and cycle stability of the battery. Without carbon coating, the conductivity of the material decreases, resulting in poor rate performance and cycle life of the battery. Carbon coating can effectively coat the cathode material, reduce the structural damage during the charge and discharge process of the material, and improve the cycle stability of the material. Without carbon coating, the structural stability of the material decreases, resulting in faster capacity decay after multiple charge and discharge cycles of the battery.

Claims

1. A material for a positive electrode of a battery, characterized in that: It comprises a core, a first shell and a second shell arranged in sequence from the inside to the outside; calculated by mass, The core body comprises 40 to 50 parts of positive electrode powder and 30 to 40 parts of solvent; The first shell layer is coated on the surface of the core body, and the first shell layer contains 5 to 7 portions of carbon source materials, and the carbon source materials are taken from sugars; The second shell layer is coated on the surface of the first shell layer, and the second shell layer contains 3 to 5 parts of nano solid electrolyte powder and 5 to 15 parts of solvent.

2. The battery positive electrode material according to claim 1, characterized in that: The positive electrode powder is any one of polycrystalline high-nickel ternary positive electrode powder, lithium cobalt oxide positive electrode powder, lithium manganese oxide positive electrode powder, and lithium iron phosphate positive electrode powder.

3. The battery positive electrode material according to claim 1, characterized in that: The carbon source material is any one of glucose powder or fructose powder.

4. The battery positive electrode material according to claim 1, characterized in that: The nano solid electrolyte powder is any one of LTPSO powder, LATP powder, LLZO powder and LLTO powder.

5. The battery positive electrode material according to claim 4, characterized in that: The particle size of the nano solid electrolyte powder is 100nm to 170nm.

6. The positive electrode material for a battery according to any one of claims 1 to 5, characterized in that: The solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide and deionized water.

7. A method for preparing a positive electrode material for a battery, characterized in that: Includes steps: S1. Mix 40 to 50 parts of the positive electrode powder and 30 to 40 parts of the solvent, and evenly disperse them by ball milling to obtain a core body; S2. Add 5 to 7 parts of carbon source material to the core, wherein the carbon source material is taken from sugars, and the carbon source material is evenly dispersed by ball milling to obtain a material coated with the first shell layer; S3. Remove bubbles and dry, sieve the material coated with the first shell layer to remove bubbles and spray dry to obtain a dried material; S4. Mix 3 to 5 parts of the nano solid electrolyte powder with 5 to 15 parts of the solvent and disperse them evenly to obtain a second shell material; S5. Spraying the second shell material on the surface of the dried material and sintering to obtain the battery positive electrode material.

8. A positive electrode, characterized in that: The positive electrode material of the battery comprises any one of claims 1 to 7; and further comprises a conductive agent, a binder and an aluminum foil.

9. A lithium battery comprising a positive electrode plate, characterized in that: The positive electrode sheet contains the battery positive electrode material according to any one of claims 1 to 6; or The positive electrode sheet contains the battery positive electrode material prepared by the method of claim 7; or The positive electrode sheet is the positive electrode sheet according to claim 8.

10. The lithium battery according to claim 9, characterized in that: Each gram of battery material stores 205 mAh of electricity when charged and discharged at a rate of 1C in a voltage range of 2.8V to 4.3V; after 800 charge and discharge cycles, the capacity of the lithium battery is ≥ 90% of the initial capacity of the lithium battery.

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