Lithium-rich metal oxide, preparation method thereof, positive electrode sheet, battery cell, and battery

Abstract

The application provides a lithium-rich metal oxide and a preparation method thereof, a positive electrode sheet, a battery monomer and a battery. The lithium-rich metal oxide comprises a lithium-rich metal oxide core; a coating layer, the coating layer comprises an organic layer and a carbon material, the organic layer coats the lithium-rich metal oxide core, and at least part of the carbon material is embedded in the organic layer. The lithium-rich metal oxide has high stability and conductivity, and is beneficial to improving the performance of the battery monomer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a lithium-rich metal oxide, a preparation method thereof, a positive electrode sheet, a battery cell and a battery. BACKGROUND

[0002] With the increasing environmental pollution, new energy industry is attracting more and more attention. In the new energy industry, battery technology is an important factor for its development.

[0003] The lithium-rich metal oxide is a material for preparing a positive electrode sheet of a battery cell, and is crucial to the performance of the battery cell. Therefore, how to provide a lithium-rich metal oxide that can balance the stability and conductivity of the lithium-rich metal oxide to improve the performance of the battery cell is an urgent technical problem to be solved. SUMMARY

[0004] The present application is carried out in view of the above-mentioned problems, and aims to provide a lithium-rich metal oxide that balances stability and conductivity to improve the performance of a battery cell.

[0005] In order to achieve the above-mentioned purpose, the present application provides a lithium-rich metal oxide, a preparation method thereof, a positive electrode sheet, a battery cell and a battery.

[0006] In a first aspect, the present application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core; a coating layer, the coating layer comprising an organic layer and a carbonaceous material, the organic layer coating the lithium-rich metal oxide core, and at least part of the carbonaceous material being embedded in the organic layer.

[0007] The present application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core and a coating layer, the coating layer comprising an organic layer and a carbonaceous material, the organic layer coating the lithium-rich metal oxide core, and the carbonaceous material being embedded in the organic layer. The content of lithium ions in the lithium-rich metal oxide core is higher than that in general lithium-containing metal oxides, and the selection of the lithium-rich metal oxide core for preparing a positive electrode material is conducive to improving the charging capacity of the battery cell. The organic layer coating the lithium-rich metal oxide core can reduce the risk of reaction of the lithium-rich metal oxide core with water, carbon dioxide and the like in the air, thereby reducing the influence of the by-products generated on the surface of the lithium-rich metal oxide core on the processing of the positive electrode sheet, and reducing the influence of the by-products on the lithium ion release in the lithium-rich metal oxide core, thereby reducing the influence on the charging capacity of the battery cell. In addition, the carbonaceous material embedded in the organic layer is conducive to improving the conductivity of the lithium-rich metal oxide. Therefore, the lithium-rich metal oxide of the present application has high stability and conductivity, and when the lithium-rich metal oxide of the present application is applied to a battery cell, it is conducive to improving the performance of the battery cell.

[0008] In a possible implementation, the carbonaceous material penetrates through the organic layer. In this way, on the one hand, the conductivity of the lithium-rich metal oxide is further improved; on the other hand, the carbonaceous material can serve as a channel for ion transmission, which is conducive to improving the diffusion coefficient of ions, such as lithium ions.

[0009] In a possible implementation, the carbonaceous material includes elemental carbon material; optionally, the elemental carbon material includes one-dimensional carbon material; optionally, the one-dimensional carbon material includes carbon nanotubes.

[0010] In the above solution, the carbonaceous material includes elemental carbon material, which can reduce the influence of decomposition of the carbonaceous material on the conductivity of the lithium-rich metal oxide during the process of coating the lithium-rich metal oxide. The elemental carbon material includes one-dimensional carbon material, which is conducive to embedding or penetrating the carbonaceous material in the organic layer. The one-dimensional carbon material includes carbon nanotubes, which are conducive to improving the electronic conductivity of the lithium-rich metal oxide due to the high conductivity of the carbon nanotubes. In addition, the hollow pipe inside the carbon nanotube can accommodate electrolyte, the electrolyte can contact the lithium-rich metal oxide core through the hollow pipe, and the hollow pipe can also serve as an ion channel to transmit lithium ions. Therefore, by selecting carbon nanotubes as the carbonaceous material, the conductivity of the lithium-rich metal oxide is further improved.

[0011] In a possible implementation, the carbon nanotubes include one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes. In this way, different types of carbon nanotubes can be flexibly selected according to actual conditions.

[0012] In a possible implementation, the aspect ratio of the carbon nanotubes is 100:1 to 1000:1, and optionally 200:1 to 400:1. If the aspect ratio of the carbon nanotubes is too large, the carbon nanotubes are prone to agglomeration. In this way, the dispersion of the carbon nanotubes is not good during the process of coating the lithium-rich metal oxide core, which is not conducive to uniformly coating the lithium-rich metal oxide core with the carbon nanotubes. If the aspect ratio of the carbon nanotubes is too small, the transmission effect of the carbon nanotubes on electrons and ions is affected. By setting the aspect ratio of the carbon nanotubes to a suitable range, the coating effect on the lithium-rich metal oxide core and the conductivity of the lithium-rich metal oxide can be considered.

[0013] In a possible implementation, the mass ratio of the carbon nanotubes to the lithium-rich metal oxide is 0.2% to 2%, or 0.5% to 1.5%. If the content of the carbon nanotubes is too high, agglomeration is likely to occur in the mixing process, which is not conducive to the uniformity of the coating and affects the stability of the lithium-rich metal oxide. If the content of the carbon nanotubes is too low, the conductivity of the lithium-rich metal oxide decreases, the transmission path and diffusion path of lithium ions are reduced, and the charging capacity of the battery cell prepared from the lithium-rich metal oxide is affected. By reasonably setting the proportion of the carbon nanotubes in the lithium-rich metal oxide, the stability and conductivity of the lithium-rich metal oxide and the charging capacity of the battery cell can be considered.

[0014] In a possible implementation, the softening temperature of the organic layer is not higher than 450°C, or not higher than 300°C. After the organic matter softens, it is in a flow state and can uniformly coat the lithium-rich metal oxide core in a large range. By selecting an organic matter with a low softening temperature, uniform and dense coating of the lithium-rich metal oxide core can be achieved at a low temperature.

[0015] In a possible implementation, the median particle size Dv 50 of the lithium-rich metal oxide is 2 μm to 10 μm, or 4 μm to 8 μm. If the median particle size of the lithium-rich metal oxide is too large, the path of lithium ions from the lithium-rich metal oxide core is too long, which is not conducive to the release of lithium ions and affects the charging capacity of the battery cell prepared from the lithium-rich metal oxide. If the median particle size of the lithium-rich metal oxide is too small, the surface activity of the lithium-rich metal oxide is strong, and the lithium-rich metal oxide particles or lithium-rich metal oxide core particles are likely to agglomerate, which is poor in particle dispersion and is not conducive to the uniformity of the coating. By reasonably setting the median particle size of the lithium-rich metal oxide, the uniformity of the coating of the lithium-rich metal oxide and the charging capacity of the battery cell can be considered.

[0016] In a possible implementation, the mass ratio of the coating layer to the lithium-rich metal oxide is 1% to 10%, or 3% to 7%. If the content of the coating layer is too high, the release of lithium ions is inhibited, which affects the charging capacity of the battery cell. If the content of the coating layer is too low, it is not conducive to the formation of a uniform and complete coating on the surface of the lithium-rich metal oxide core, the coating effect is poor, the stability of the lithium-rich metal oxide is poor, and the charging capacity of the battery cell is affected.

[0017] In a possible implementation, the material of the lithium-rich metal oxide core includes Li a M n O y , 2≤a≤8, the Li a M n O y includes Li2M 1O2, Li2M 2 O3, Li3M 3 O4, Li5M 4 O4, Li6M 5 O4, Li8M 6 One or more of O6; M 1 Including one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, and Mo; M 2 Includes one or more of Mn, Sn, Mo, Ru, and Ir; M 3 Including one or more of V, Nb, Cr, and Mo; M 4 Including one or more of Fe, Cr, V, and Mo; M 5 Including one or more of Co, V, Cr, and Mo; M 6 Including Sn; optionally, the Li a M n O y This includes one or more of the following: Li₂NiO₂, Li₂CuO₂, Li₂MnO₃, Li₃VO₄, Li₃NbO₄, Li₅FeO₄, Li₆CoO₄, and Li₈SnO₆. This allows for flexible selection of suitable lithium-rich metal oxide cores based on actual needs.

[0018] In one possible implementation, the material of the organic layer includes one or more of rubber, asphalt, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene; alternatively, the material of the organic layer includes one or more of rubber, asphalt, and polyvinylidene fluoride. This allows for flexible selection of the organic layer material according to actual needs.

[0019] Secondly, this application provides a method for preparing lithium-rich metal oxides, comprising: providing a lithium-rich metal oxide core, a carbonaceous material, and an organic compound; mixing the lithium-rich metal oxide core, the carbonaceous material, and the organic compound, and processing them to obtain the lithium-rich metal oxide. The lithium-rich metal oxide prepared by this method exhibits high conductivity and stability. When the lithium-rich metal oxide of this application is applied to battery cells, it is beneficial to improving the performance of the battery cells.

[0020] In one possible implementation, the process includes sintering in an inert atmosphere for 2 to 6 hours. This facilitates obtaining a uniformly coated lithium-rich metal oxide. Optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium. This allows for the selection of a suitable inert gas according to actual needs. Optionally, the processing temperature does not exceed 500°C, and the sintering temperature does not exceed 300°C. This allows for the formation of lithium-rich metal oxides with a uniform and dense coating at relatively low temperatures.

[0021] In one possible implementation, the method further includes sieving the processed product to obtain the lithium-rich metal oxide. This facilitates obtaining lithium-rich metal oxides with suitable particle size.

[0022] In one possible implementation, the carbonaceous material includes elemental carbon material; optionally, the elemental carbon material includes one-dimensional carbon material; optionally, the one-dimensional carbon material includes carbon nanotubes. This reduces the impact of carbonaceous material decomposition during the preparation of lithium-rich metal oxides on the conductivity of the lithium-rich metal oxides. Including one-dimensional carbon material in the elemental carbon material facilitates the embedding or penetration of carbonaceous material within the organic layer. Including carbon nanotubes in the one-dimensional carbon material is beneficial for improving the electronic conductivity of lithium-rich metal oxides due to the high conductivity of carbon nanotubes; furthermore, the hollow channels inside the carbon nanotubes can accommodate electrolytes, allowing the electrolyte to contact the lithium-rich metal oxide core through the hollow channels, which can also act as ion channels for lithium ion transport. Therefore, selecting carbon nanotubes as the carbonaceous material further improves the conductivity of lithium-rich metal oxides.

[0023] In one possible implementation, the carbon nanotubes include one or more types of single-walled carbon nanotubes and multi-walled carbon nanotubes. This allows for flexible selection of different types of carbon nanotubes based on actual needs.

[0024] In one possible implementation, the aspect ratio of the carbon nanotubes is 100:1 to 1000:1, preferably 200:1 to 400:1. This balances the coating effect on the lithium-rich metal oxide core with the conductivity of the lithium-rich metal oxide.

[0025] In one possible implementation, the softening temperature of the organic material is lower than the processing temperature; optionally, the softening temperature of the organic material does not exceed 450°C, or optionally, does not exceed 300°C. In this way, the organic material softens at the sintering temperature, thereby forming a flow dynamic, which facilitates uniform and dense coating of the lithium-rich metal oxide core.

[0026] In one possible implementation, the organic material includes one or more of rubber, asphalt, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene; optionally, the organic material includes one or more of rubber, asphalt, and polyvinylidene fluoride. This allows for flexible selection of the organic material according to actual needs.

[0027] In one possible implementation, providing the lithium-rich metal oxide core includes: uniformly mixing a Li source and a Mn source at a molar ratio of (a+0.05):1 to a:1, and then sintering them at a single temperature rise for 4 to 8 hours in an inert atmosphere, wherein the sintering temperature is 400℃ to 600℃; wherein the Li source includes one or more of lithium oxide, lithium carbonate, lithium oxalate, lithium acetate, and lithium hydroxide, and the Mn source includes one or more of Mn oxides, hydroxides, halides, sulfates, carbonates, nitrates, oxalates, acetates, sulfides, and nitrides; optionally, the sintering temperature is 450℃ to 550℃; optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium; and the product of the single-temperature sintering is subjected to airflow breakup to obtain the lithium-rich metal oxide core. This facilitates the preparation of a suitable lithium-rich metal oxide core, which is beneficial for the subsequent preparation of lithium-rich metal oxides.

[0028] Thirdly, a positive electrode is provided, comprising the lithium-rich metal oxide of the first aspect and any possible implementation thereof.

[0029] Fourthly, a battery cell is provided, including the positive electrode sheet described in the third aspect.

[0030] Fifthly, a battery is provided, comprising the battery cell described in the fourth aspect.

[0031] In a sixth aspect, an electrical device is provided, comprising the battery described in the fifth aspect.

[0032] This application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core and a coating layer. The coating layer includes an organic layer and a carbonaceous material. The organic layer coats the lithium-rich metal oxide core, and the carbonaceous material is embedded in the organic layer. The lithium-ion content in the lithium-rich metal oxide core is higher than that in typical lithium-containing metal oxides. Using a lithium-rich metal oxide core to prepare the cathode material is beneficial for improving the charging capacity of the battery cell. Coating the lithium-rich metal oxide core with an organic layer reduces the risk of reaction between the lithium-rich metal oxide core and water, carbon dioxide, etc., in the air. This reduces the impact of byproducts generated on the surface of the lithium-rich metal oxide core on the processing of the cathode sheet and minimizes the impact of byproducts on the release of lithium ions from the core, thereby reducing the impact on the charging capacity of the battery cell. Furthermore, the embedding of the carbonaceous material in the organic layer improves the conductivity of the lithium-rich metal oxide. Therefore, the lithium-rich metal oxide of this application exhibits high stability and conductivity, which is beneficial for improving the performance of battery cells when applied to them. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a lithium-rich metal oxide according to an embodiment of this application;

[0034] Figure 2 This is a flowchart of a method for preparing lithium-rich metal oxides according to an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of a battery cell according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of a battery module according to an embodiment of this application;

[0037] Figure 5 This is a schematic diagram of a battery according to an embodiment of this application;

[0038] Figure 6 This is a schematic diagram of an electrical device according to an embodiment of this application;

[0039] Figure 7 A schematic diagram of a scanning electron microscope for lithium-rich metal oxides without a coating layer;

[0040] Figure 8 This is a schematic diagram of a scanning electron microscope of a lithium-rich metal oxide with a coating layer as described in this application. Detailed Implementation

[0041] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the negative electrode, secondary battery, battery module, battery pack, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0042] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] Lithium-ion batteries are widely used in mobile phones, electric vehicles, and energy storage stations due to their high energy density, high voltage, and long lifespan. The lithium-rich metal oxides in lithium-ion batteries are crucial to their performance, such as capacity and other properties.

[0049] Lithium-rich metal oxides, with their high lithium-ion content, are widely used in the fabrication of lithium-ion batteries. However, they suffer from poor stability. Current technologies typically employ carbon or polymer coatings to improve their performance, thereby enhancing conductivity or stability. However, the applicant's research has revealed that this method of coating lithium-rich metal oxides with only a single carbon source often fails to balance stability and conductivity, hindering the overall improvement of the lithium-rich metal oxide's performance and consequently, the performance of the lithium-ion battery.

[0050] In view of this, this application provides a lithium-rich metal oxide, wherein the coating layer of the lithium-rich metal oxide includes organic matter and carbonaceous materials, which can balance the stability and conductivity of the lithium-rich metal oxide, and is beneficial to improving the performance of the battery cell.

[0051] [Lithium-rich metal oxides]

[0052] Figure 1This is a schematic diagram of a lithium-rich metal oxide according to an embodiment of this application. Figure 1 As shown, the lithium-rich metal oxide 1 includes a lithium-rich metal oxide core 11 and a coating layer 12.

[0053] The lithium ion content in the lithium-rich metal oxide core 11 is higher than that in general lithium-containing metal oxides. Selecting the lithium-rich metal oxide core 11 to prepare battery cells is beneficial to improving the charging capacity of battery cells.

[0054] The coating layer 12 coats the lithium-rich metal oxide core 11, meaning that the lithium-rich metal oxide core 11, as the core of the lithium-rich metal oxide 1, is coated inside the coating layer 12.

[0055] The coating layer 12 includes an organic layer 121 and a carbonaceous material 122. The organic layer 121 coats the lithium-rich metal oxide core 11, and at least a portion of the carbonaceous material 122 is embedded in the organic layer 121.

[0056] The organic layer 121 is a material layer formed of organic matter, which covers the outer surface of the lithium-rich metal oxide core 11.

[0057] The lithium-rich metal oxide core 11 readily reacts with water, carbon dioxide, and other substances in the air, generating byproducts such as lithium-containing inert compounds like Li₂CO₃ and LiOH on its surface. These byproducts or lithium-containing inert compounds remain free on the surface of the lithium-rich metal oxide core 11, affecting the extraction of lithium ions and leading to a decrease in the performance of the lithium-rich metal oxide and the charging capacity of the battery cells. Furthermore, the lithium-containing inert compounds are highly alkaline. When the lithium-rich metal oxide core 11 is mixed with a binder to form a slurry for preparing the positive electrode, these inert compounds affect the performance of the binder, causing denaturation of binders such as polyvinylidene fluoride (PVDF), thus affecting the performance and coating of the slurry and consequently impacting the processing of the positive electrode.

[0058] By using an organic layer 121 to coat the lithium-rich metal oxide core 11, the risk of side reactions in the lithium-rich metal oxide core 11 can be reduced, which is beneficial to improving the stability of the lithium-rich metal oxide 1. It can also reduce the impact of lithium-containing inert compounds on the processing of the positive electrode sheet, and reduce the impact of by-products on the charging capacity of the battery cell and the performance of the lithium-rich metal oxide, which is beneficial to improving the performance of the lithium-rich metal oxide and the charging capacity of the battery cell.

[0059] Optionally, the charging capacity of a single battery cell can include the initial charging capacity of the cell, during which lithium ions are released from the positive electrode. For example, the charging capacity of a single battery cell can be the ratio of its capacity to the mass of the active material within the cell after charging is complete.

[0060] Carbonaceous material 122 includes carbon-containing, conductive materials, and may include elemental carbon materials.

[0061] At least a portion of the carbonaceous material 122 in the coating layer 12 is embedded in the organic layer 121. For example, the coating layer 12 includes a plurality of carbonaceous material particles, and at least one carbonaceous material particle is embedded in the organic layer 121.

[0062] Embedding may include: a portion of the carbonaceous material particles being embedded in the organic layer 121, the carbonaceous material particles being adsorbed onto the organic layer 121, or all of the carbonaceous material particles being embedded in the organic layer 121.

[0063] By embedding carbonaceous material 122 into organic layer 121, it is beneficial to improve the conductivity of organic layer 121, that is, to reduce the resistivity of lithium-rich metal oxide 1 and improve the conductivity of lithium-rich metal oxide 1.

[0064] Optionally, the lithium-rich metal oxide 1 of this application can be used as a lithium replenishing agent. Optionally, the lithium-rich metal oxide of this application can also be used as an activator, after being mixed with a binder and a conductive agent, to prepare a positive electrode sheet.

[0065] This application provides a lithium-rich metal oxide 1, comprising a lithium-rich metal oxide core 11 and a coating layer 12. The coating layer 12 includes an organic layer 121 and a carbonaceous material 122. The organic layer 121 coats the lithium-rich metal oxide core 11, and the carbonaceous material 122 is embedded in the organic layer 121. The lithium-ion content in the lithium-rich metal oxide core 11 is higher than that in general lithium-containing metal oxides. Using a lithium-rich metal oxide core 11 to prepare the cathode material is beneficial for improving the charging capacity of the battery cell. Coating the lithium-rich metal oxide core 11 with the organic layer 121 reduces the risk of the lithium-rich metal oxide core 11 reacting with water, carbon dioxide, etc., in the air. This reduces the impact of byproducts generated on the surface of the lithium-rich metal oxide core 11 on the processing of the cathode sheet and reduces the impact of byproducts on the extraction of lithium ions from the lithium-rich metal oxide core 11, thereby reducing the impact on the charging capacity of the battery cell. Furthermore, the embedding of the carbonaceous material 122 in the organic layer 121 is beneficial for improving the conductivity of the lithium-rich metal oxide 1. Therefore, the lithium-rich metal oxide 1 of this application has high stability and conductivity. When the lithium-rich metal oxide 1 of this application is applied to a battery cell, it is beneficial to improve the performance of the battery cell.

[0066] In some embodiments, at least a portion of the carbonaceous material 122 penetrates the organic layer 121. Alternatively, the carbonaceous material 122 may be embedded in the organic layer 121 and extend from the surface of the organic layer 121 near the lithium-rich metal oxide core 11 to the surface of the organic layer 121 away from the lithium-rich metal oxide core 11. Thus, the carbonaceous material 122 is in contact with both the lithium-rich metal oxide core 11 and the exterior of the lithium-rich metal oxide 11, such as with the electrolyte or electrolyte solution.

[0067] Optionally, at least a portion of the carbonaceous material 122 penetrates the organic layer 121 and extends to the surface of the organic layer 121 away from the lithium-rich metal oxide core 11. In this way, the carbonaceous material 122 can come into contact with the external environment, such as the electrolyte, and can be used to transport lithium ions.

[0068] In the above embodiments, at least a portion of the carbonaceous material 122 penetrates the organic layer 121. This is beneficial in two ways: firstly, it helps to further improve the conductivity of the lithium-rich metal oxide 1; secondly, the carbonaceous material 122 can serve as a channel for ion transport, which helps to improve the diffusion coefficient of ions, such as lithium ions.

[0069] In some embodiments, the carbonaceous material 122 comprises elemental carbon. This reduces the impact of the decomposition of the carbonaceous material 122 during the coating process of the lithium-rich metal oxide 1 on the conductivity of the lithium-rich metal oxide 1.

[0070] Elemental carbon materials can include zero-dimensional carbon materials, one-dimensional carbon materials, and two-dimensional carbon materials. Zero-dimensional carbon materials can include carbon black, fullerene C60, etc.; one-dimensional carbon materials can include carbon nanotubes with internal hollow structures, carbon nanofibers without obvious internal hollow structures, etc.; two-dimensional carbon materials can include graphene, etc.

[0071] Optionally, in some embodiments, the elemental carbon material 122 comprises a one-dimensional carbon material. This facilitates the embedding or penetration of carbonaceous material within the organic layer 121.

[0072] Optionally, in some embodiments, the one-dimensional carbon material includes carbon nanotubes.

[0073] Carbon nanotubes exhibit high electrical conductivity, and incorporating them into the coating layer 12 is beneficial for improving the electronic conductivity of the lithium-rich metal oxide 1. Furthermore, the hollow channels within the carbon nanotubes can accommodate the electrolyte, allowing it to contact the lithium-rich metal oxide core 11. These hollow channels also serve as ion channels for lithium ion transport. Therefore, selecting carbon nanotubes as the carbonaceous material 122 is beneficial for further improving the electrical conductivity of the lithium-rich metal oxide 1.

[0074] In some embodiments, carbon nanotubes include one or more types of single-walled carbon nanotubes and multi-walled carbon nanotubes. This allows for flexible selection of different types of carbon nanotubes according to actual needs.

[0075] In some embodiments, the aspect ratio of the carbon nanotubes is 100:1 to 1000:1, and can be selected as 200:1 to 400:1.

[0076] The aspect ratio of carbon nanotubes is the ratio of the length to the outer diameter of the carbon nanotube.

[0077] When the aspect ratio of carbon nanotubes is greater than 1000:1, the carbon nanotubes are relatively long and prone to aggregation. As a result, the dispersion of carbon nanotubes is poor during the coating process of lithium-rich metal oxide core 11, which is not conducive to the uniform coating of lithium-rich metal oxide core 11 by carbon nanotubes.

[0078] When the aspect ratio of carbon nanotubes is less than 100:1, the length of the carbon nanotubes is relatively small, and the hollow channels of the carbon nanotubes are relatively short, which affects the transmission effect of carbon nanotubes on electrons and ions.

[0079] In this embodiment, by setting the aspect ratio of the carbon nanotubes to 100:1 to 1000:1, both the coating effect on the lithium-rich metal oxide core 11 and the conductivity of the lithium-rich metal oxide 1 can be taken into account.

[0080] Optionally, by setting the aspect ratio of the carbon nanotubes to 200:1 to 400:1, it is beneficial to further improve the coating effect on the lithium-rich metal oxide core 11 and the conductivity of the lithium-rich metal oxide 1.

[0081] In some embodiments, the mass ratio of carbon nanotubes to lithium-rich metal oxide 1 is 0.2% to 2%, optionally 0.5% to 1.5%.

[0082] When the mass ratio of carbon nanotubes to lithium-rich metal oxide 1 is greater than 2%, carbon nanotubes will agglomerate during the mixing process, or during the mixing process of carbon nanotubes with organic matter and lithium-rich metal oxide core 11. This is not conducive to achieving uniform coating and affects the coating effect and the stability of lithium-rich metal oxide 1.

[0083] When the mass ratio of carbon nanotubes to lithium-rich metal oxide is less than 0.2%, the carbon nanotube content is too low, the conductivity of lithium-rich metal oxide 1 decreases, and the lithium ion transport and diffusion paths are reduced, affecting the performance of lithium-rich metal oxide 1 and the charging capacity of the prepared battery cell.

[0084] In this embodiment, by setting the mass ratio of carbon nanotubes to lithium-rich metal oxide 1 to 0.2% to 2%, it is beneficial to balance the stability and conductivity of lithium-rich metal oxide 1, as well as the charging capacity of the battery cell.

[0085] Optionally, the mass ratio of carbon nanotubes to lithium-rich metal oxide 1 is 0.5% to 1.5%, which is beneficial to further improve the stability and conductivity of lithium-rich metal oxide 1, as well as the charging capacity of the battery cell.

[0086] In some embodiments, the softening temperature of the organic layer 121 does not exceed 450°C, and optionally, does not exceed 300°C.

[0087] The softening temperature can be the temperature at which an organic material changes from a solid state to a fluid state, or the temperature at which an organic material changes from a solid state to a molten state. After reaching the softening temperature, the organic material becomes either fluid or molten.

[0088] The organic material softens and melts, becoming fluid, and can uniformly coat the lithium-rich metal oxide core 11 over a large area, thereby forming an organic layer 121. By selecting an organic material with a low softening temperature, uniform and dense coating of the lithium-rich metal oxide core 11 can be achieved at a lower temperature.

[0089] In some embodiments, the median particle size Dv of lithium-rich metal oxide 1 50 The range is 2μm to 10μm, and can be selected from 4μm to 8μm.

[0090] Median particle size Dv 50 It can refer to the particle size corresponding to a cumulative volume distribution percentage of 50% for a sample.

[0091] Median particle size Dv of lithium-rich metal oxide 1 50 It is related to the median particle size of the lithium-rich metal oxide core 11. The larger the median particle size of the lithium-rich metal oxide core 11, the larger the median particle size Dv of the lithium-rich metal oxide 1. 50 The larger the median particle size of lithium-rich metal oxide core 11, the smaller the median particle size Dv of lithium-rich metal oxide 1. 50 The smaller.

[0092] The median particle size Dv of lithium-rich metal oxide 1 50 When the core size is greater than 10 μm, the path for lithium ions to escape from the lithium-rich metal oxide core 11 is too long, which is not conducive to the extraction of lithium ions and affects the performance of the lithium-rich metal oxide 1 and the capacity of the prepared battery cell.

[0093] The median particle size Dv of lithium-rich metal oxide 1 50When the particle size is less than 2 μm, the surface activity of lithium-rich metal oxide 1 is strong, and the lithium-rich metal oxide particles or lithium-rich metal oxide core particles are prone to agglomeration, resulting in poor particle dispersion, which is not conducive to achieving uniform coating.

[0094] In this embodiment, the median particle size Dv of the lithium-rich metal oxide 1 is set. 50 With a thickness of 2μm to 10μm, it can balance the uniformity of the coating of lithium-rich metal oxide 1 with the capacity of the battery cell prepared by lithium-rich metal oxide.

[0095] Optionally, the median particle size Dv of lithium-rich metal oxide 1 50 The thickness is 4μm to 8μm, which is beneficial to further improve the coating uniformity of lithium-rich metal oxide 1 and the capacity of the battery cell.

[0096] In some embodiments, the mass ratio of the coating layer 12 to the lithium-rich metal oxide 1 is 1% to 10%, and optionally 3% to 7%.

[0097] When the mass ratio of the lithium-rich metal oxide 1 in the coating layer 12 is greater than 10%, the excessive content of the coating layer 12 will inhibit the release of lithium ions and affect the charging capacity of the battery cell.

[0098] When the mass ratio of the lithium-rich metal oxide 1 in the coating layer 12 is less than 1%, the content of the coating layer 12 is too low, which is not conducive to forming a uniform and complete coating on the surface of the lithium-rich metal oxide core 11. The coating effect is poor, the stability of the lithium-rich metal oxide 1 is poor, and the charging capacity of the battery cell is also affected.

[0099] In this embodiment, by setting the mass ratio of the coating layer 12 to the lithium-rich metal oxide 1 to 1% to 10%, the stability of the lithium-rich metal oxide 1 and the capacity of the prepared battery cell can be balanced.

[0100] Optionally, the mass ratio of the coating layer 12 to the lithium-rich metal oxide 1 is 3% to 7%, which is beneficial to further improve the stability of the lithium-rich metal oxide 1 and the capacity of the prepared battery cell.

[0101] In some embodiments, the material of the lithium-rich metal oxide core 11 includes Li a M n O y , 2≤a≤8, Li a M n O y Including Li2M 1 O2, Li2M 2 O3, Li3M 3 O4, Li5M 4 O4, Li6M 5O4, Li8M 6 One or more of O6; M 1 Including one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, and Mo; M 2 Includes one or more of Mn, Sn, Mo, Ru, and Ir; M 3 Including one or more of V, Nb, Cr, and Mo; M 4 Including one or more of Fe, Cr, V, and Mo; M 5 Including one or more of Co, V, Cr, and Mo; M 6 Including Sn; optionally, Li a M n O y This includes one or more of the following: Li₂NiO₂, Li₂CuO₂, Li₂MnO₃, Li₃VO₄, Li₃NbO₄, Li₅FeO₄, Li₆CoO₄, and Li₈SnO₆. This allows for flexible selection of suitable lithium-rich metal oxide cores based on actual needs.

[0102] In some embodiments, the material of the organic layer 121 includes one or more of rubber, asphalt, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene; optionally, the material of the organic layer 121 includes one or more of rubber, asphalt, and polyvinylidene fluoride. This allows for flexible selection of the material of the organic layer according to actual needs.

[0103] The softening temperature of rubber is approximately 140℃, that of asphalt is approximately 250℃, that of polypropylene is approximately 165℃, that of polyethylene is approximately 180℃, that of polystyrene is approximately 166℃, that of polycarbonate is approximately 215℃, that of polymethyl methacrylate is approximately 160℃, that of polyethylene terephthalate is approximately 250℃, that of polyvinylidene fluoride is approximately 160℃, and that of polytetrafluoroethylene is approximately 330℃.

[0104] The above text combined Figure 1 This paper describes embodiments of the lithium-rich metal oxides of this application, and embodiments of the preparation methods of the lithium-rich metal oxides will be detailed below. In the embodiments of the preparation methods of the lithium-rich metal oxides, any parts not described herein can be referred to the relevant descriptions of the embodiments of the lithium-rich metal oxides.

[0105] [Methods for preparing lithium-rich metal oxides]

[0106] Figure 2 This is a flowchart illustrating a method for preparing lithium-rich metal oxides according to an embodiment of this application.Figure 2 As shown, the method 200 for preparing lithium-rich metal oxides includes the following steps.

[0107] Step 210: Provide a lithium-rich metal oxide core, carbonaceous materials, and organic matter.

[0108] Step 220: Mix the lithium-rich metal oxide core, carbonaceous material and organic matter, and process them to obtain lithium-rich metal oxide.

[0109] The lithium-rich metal oxide 1 prepared by the method of this application has high conductivity and stability, which is beneficial to the improvement of the performance of battery cells.

[0110] Optionally, the lithium-rich metal oxide prepared by method 200 is the same as the lithium-rich metal oxide described above. Alternatively, the lithium-rich metal oxide prepared by method 200 may also differ structurally from the lithium-rich metal oxide described above.

[0111] In some embodiments, the above treatment includes sintering in an inert atmosphere for 2 to 6 hours. This facilitates the obtaining of a uniformly coated lithium-rich metal oxide 1.

[0112] In some embodiments, the inert atmosphere includes one or more of nitrogen, argon, and helium. This facilitates the selection of a suitable inert gas according to actual needs.

[0113] In some embodiments, the temperature of the above-described process does not exceed 500°C; alternatively, the temperature does not exceed... In this way, lithium-rich metal oxides with uniform and dense coatings can be achieved at lower temperatures.

[0114] In some embodiments, the method further includes: sieving the product after the above treatment to obtain lithium-rich metal oxide 1. This facilitates obtaining lithium-rich metal oxide 1 with a suitable particle size.

[0115] In some embodiments, the carbonaceous material includes elemental carbon material; optionally, the elemental carbon material includes one-dimensional carbon material; optionally, the one-dimensional carbon material includes carbon nanotubes. This reduces the impact of carbonaceous material decomposition during the preparation of lithium-rich metal oxides on the conductivity of the lithium-rich metal oxides. Including one-dimensional carbon material in the elemental carbon material facilitates the embedding or penetration of carbonaceous material within the organic layer. Including carbon nanotubes in the one-dimensional carbon material is beneficial for improving the electronic conductivity of lithium-rich metal oxides due to the high conductivity of carbon nanotubes; furthermore, the hollow channels inside the carbon nanotubes can accommodate electrolytes, allowing the electrolyte to contact the lithium-rich metal oxide core through the hollow channels, which can also act as ion channels for lithium ion transport. Therefore, selecting carbon nanotubes as the carbonaceous material further improves the conductivity of lithium-rich metal oxides.

[0116] Optionally, carbon nanotubes include one or more types of single-walled carbon nanotubes and multi-walled carbon nanotubes. This allows for flexible selection of different types of carbon nanotubes based on actual needs.

[0117] In some embodiments, the aspect ratio of the carbon nanotubes is 100:1 to 1000:1, and can be selected as 200:1 to 400:1. This balances the coating effect on the lithium-rich metal oxide core with the conductivity of the lithium-rich metal oxide.

[0118] In some embodiments, the softening temperature of the organic material is lower than the sintering temperature. Optionally, the softening temperature of the organic material does not exceed 450°C, and optionally, it does not exceed 300°C. In this way, the organic material softens at the sintering temperature, thereby forming a flow dynamic, which facilitates the uniform and dense coating of the lithium-rich metal oxide core.

[0119] In some embodiments, the organic material includes one or more of rubber, asphalt, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene; optionally, the organic material includes one or more of rubber, asphalt, and polyvinylidene fluoride. This allows for flexible selection of the organic material according to actual needs.

[0120] In some embodiments, a lithium-rich metal oxide core is provided, comprising: uniformly mixing a Li source and a Mn source at a molar ratio of (a+0.05):1 to a:1, and then sintering them at a single heating temperature of 400℃ to 600℃ in an inert atmosphere for 4h to 8h; wherein the Li source includes one or more of lithium oxide, lithium carbonate, lithium oxalate, lithium acetate, and lithium hydroxide, and the Mn source includes one or more of Mn oxides, hydroxides, halides, sulfates, carbonates, nitrates, oxalates, acetates, sulfides, and nitrides; optionally, the sintering temperature is 450℃ to 550℃; optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium; and the product from the single heating sintering is subjected to airflow ablation to obtain the lithium-rich metal oxide core. This facilitates the preparation of suitable lithium-rich metal oxide cores for subsequent preparation of lithium-rich metal oxides. Furthermore, this method prepares lithium-rich metal oxide cores at a lower sintering temperature, which helps reduce costs and also helps reduce lithium volatilization.

[0121] [Positive electrode tablets]

[0122] This application provides a positive electrode, including a lithium-rich metal oxide in any of the embodiments.

[0123] [Battery cell]

[0124] This application provides a battery cell including the positive electrode sheet in the above embodiments.

[0125] This application does not impose any particular restrictions on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape.

[0126] Figure 3 This is a schematic diagram of a battery cell according to an embodiment of this application. Figure 3 As shown, the battery cell 3 includes a housing 31, a cover plate 32, and an electrode assembly 33 disposed in the housing 31.

[0127] The electrode assembly 33 can be manufactured from the positive electrode, negative electrode and separator of this application by a winding process or a stacking process.

[0128] Optionally, the battery cell 3 also includes an electrolyte. The electrolyte can be solid, semi-solid, or liquid, and this application embodiment does not impose specific limitations on this.

[0129] In some embodiments, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0130] Figure 4 This is a schematic diagram of a battery module according to an embodiment of this application. (Refer to...) Figure 4 In the battery module 4, multiple battery cells 3 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other way. Furthermore, these multiple battery cells 3 can be fixed in place using fasteners.

[0131] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 3 are received.

[0132] [Battery]

[0133] This application provides a battery, including the battery cell described in the above embodiments.

[0134] Figure 5 This is a schematic diagram of a battery according to an embodiment of this application. Figure 5 As shown, this application provides a battery 5, including the battery cell 3 in any of the above embodiments.

[0135] Battery cells 3 can be directly assembled into battery 5, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into battery 5.

[0136] [Electrical appliances]

[0137] This application provides an electrical device, including the battery described in the above embodiments.

[0138] Figure 6 This is a schematic diagram of an electrical device according to an embodiment of this application. Figure 6 As shown, this application provides an electrical device 6, which includes the battery 5 in the above embodiment.

[0139] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. 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 this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0140] [Example]

[0141] Examples 1-9

[0142] The difference between Example 1 and Examples 2-9 is that the ratio of the mass of the coating layer to the mass of the lithium-rich metal oxide is different, that is, the total content of the coating layer is different.

[0143] Examples 10-15

[0144] The difference between Example 1 and Examples 10-15 is that the ratio of the mass of carbon nanotubes to the mass of lithium-rich metal oxides is different, that is, the content of carbon nanotubes is different.

[0145] Examples 16-21

[0146] The difference between Example 1 and Examples 16-21 is that the median particle size of the lithium-rich metal oxide is different.

[0147] Examples 22-28

[0148] The difference between Example 1 and Examples 22-28 is that the aspect ratio of the carbon nanotubes is different.

[0149] Examples 29-35

[0150] The difference between Example 1 and Examples 29-35 is that the temperature T1 is different, that is, the sintering temperature when preparing the lithium-rich metal oxide core is different.

[0151] Examples 36-41

[0152] The difference between Example 1 and Examples 36-41 is that the temperature T2 is different, that is, the temperature at which lithium-rich metal oxides are prepared using lithium-rich metal oxide cores, organic matter and carbonaceous materials is different.

[0153] Examples 42-45

[0154] The difference between Example 1 and Examples 42-45 is that the types of lithium-rich metal oxide cores are different.

[0155] Examples 46-48

[0156] The difference between Example 1 and Examples 46-48 is that the types of carbonaceous materials are different.

[0157] Examples 49-50

[0158] The difference between Example 1 and Examples 49-50 is that the types of organic matter are different.

[0159] Comparative Example 1

[0160] Comparative Example 1 did not have the lithium-rich metal oxide core coated.

[0161] Comparative Examples 2-3

[0162] Comparative Example 2 used only carbon nanotubes to coat the lithium-rich metal oxide core, while Comparative Example 3 used only pitch to coat the lithium-rich metal oxide core.

[0163] Comparative Examples 4-6

[0164] Comparative Example 4 only mixed lithium-rich metal oxide cores with carbon nanotubes without sintering; Comparative Example 5 only mixed lithium-rich metal oxide cores with pitch without sintering; Comparative Example 6 only mixed lithium-rich metal oxide cores, carbon nanotubes, and pitch without sintering.

[0165] [Preparation methods of lithium-rich metal oxides]

[0166] (1) Preparation of lithium-rich metal oxide cores

[0167] Using Li source and M n The source is supplied according to a molar ratio of (a+0.05):1 to a:1 (where M... n Includes M 1 ~M 6 After being mixed evenly, the mixture is sintered once in a nitrogen inert atmosphere. The sintering temperature is shown in Table 1 for the sintering temperature T1 of different embodiments, and the sintering time is 4h to 8h.

[0168] The Li source in Examples 1-42 includes lithium hydroxide, M n The source includes ferric oxide; the Li source in Example 43 includes lithium hydroxide, M n The source includes cobalt hydroxide; the Li source in Example 44 includes lithium hydroxide, M n The source includes copper oxide; the Li source in Example 45 includes lithium hydroxide, M n The source includes nickel hydroxide; the Li source in Example 46 includes lithium hydroxide, Mn The source includes niobium pentoxide.

[0169] The product obtained by the above-mentioned single-heat sintering was subjected to airflow crushing to obtain a lithium-rich metal oxide core.

[0170] (2) Preparation of lithium-rich metal oxides

[0171] The lithium-rich metal oxide core, carbonaceous material, and organic matter are mixed evenly and then sintered at a low temperature. Specific sintering temperature T2 and other parameters are shown in Table 1. After sintering, the mixture is sieved to obtain the lithium-rich metal oxide.

[0172] [Testing of total coating content]

[0173] The total content W of the coating layer can be determined using a high-frequency infrared carbon-sulfur analyzer (C content analyzer, model HCS-140, manufactured by Shanghai Dekai Instruments Co., Ltd.), according to GB / T 20123-2006 "Determination of total carbon and sulfur content in steel by infrared absorption method after combustion in a high-frequency induction furnace (conventional method)".

[0174] The content of organic matter in the coating layer (Wo) can be tested using a Netzsch STA449F3 thermal analyzer. Weigh 20 mg of lithium-rich metal oxide into an alumina crucible, and test the thermal weight loss rate of the lithium-rich metal oxide from 25 °C to 800 °C under an inert gas atmosphere. The heating rate can be 10 °C / min.

[0175] Specifically, 20 mg of lithium-rich metal oxide was weighed and added to an alumina crucible. The TG curve of the lithium-rich metal oxide was tested using a thermal analysis instrument under a nitrogen atmosphere to obtain its thermal weight loss rate (the percentage of weight lost due to thermal decomposition relative to the original sample weight) W. L1 The percentage and softening temperature T are used to determine the type of organic compound.

[0176] Then, by combining the TG curve of the organic compound, its weight loss rate W can be obtained. L2 % (which can be obtained by consulting relevant data or through experiments), and then calculated to get: Wo = W L1 / W L2 .

[0177] [Testing of carbon nanotube content and aspect ratio]

[0178] The carbon nanotube content Wc is equal to the total coating content W minus the organic matter content Wo.

[0179] The aspect ratio of carbon nanotubes can be measured using a transmission electron microscope. Normally, 20 well-dispersed carbon nanotubes are taken, their outer diameter and length are measured separately, and the average value is taken as the aspect ratio of the carbon nanotube.

[0180] Median particle size Dv of lithium-rich metal oxides 50 [Test]

[0181] In lithium-rich metal oxides, the median particle size Dv 50 Particle size distribution can be determined using a laser particle size analyzer, referring to GB / T 19077-2016 Laser Diffraction Method.

[0182] [Resistivity Testing of Lithium-Rich Metal Oxides]

[0183] The lithium-rich metal oxide powder was dried, and an appropriate amount of powder was weighed. Then, the powder resistivity of the sample was determined using a powder resistivity tester (ST2722 digital four-probe instrument, manufactured by Suzhou Jingge Electronics Co., Ltd.) according to GB / T 30835-2014 "Carbon composite lithium iron phosphate lithium-rich metal oxide for lithium-ion batteries". The test pressure was 20 MPa.

[0184] [Preparation of Lithium-ion Batteries]

[0185] Preparation of the positive electrode sheet: Lithium-rich metal oxide, polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 97:2:1. After thorough mixing, a positive electrode slurry is prepared. The positive electrode slurry is uniformly coated onto a positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet. In the preparation of this positive electrode sheet, lithium-rich metal oxide is used as the active material, and no other active materials are added.

[0186] Preparation of negative electrode sheet: The negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water at a mass ratio of 96:1.5:1.5:1.0 and thoroughly stirred and mixed to prepare a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector copper foil, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0187] Separating membrane: made of polypropylene membrane.

[0188] Preparation of the electrolyte: Ethyl carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1. LiPF6 was then uniformly dissolved in the mixture to obtain the electrolyte. The concentration of LiPF6 in this electrolyte was 1 mol / L.

[0189] Preparation of lithium-ion batteries: The above-mentioned positive electrode sheet, separator, and negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer packaging, the electrolyte prepared above is added, and after processes such as encapsulation, standing, formation, and aging, a lithium-ion battery is obtained.

[0190] [Testing the first charge capacity of lithium-ion batteries]

[0191] The assembled lithium-ion battery was charged at a constant current rate of 0.1C to 4.25V, and left to stand for 5 minutes. The first charge capacity of the lithium-ion battery was recorded at this time. The first charge capacity of the lithium-ion battery was obtained by dividing the first charge capacity of the battery by the mass of the lithium-rich metal oxide.

[0192] [Lithium-ion diffusion coefficient test]

[0193] The diffusion coefficient of lithium ions can be tested using conventional methods in the field, such as coin cell CV method, EIS method, GITT method, and PITT method, and calculated according to Fick's first and second laws.

[0194] Taking the GITT method as an example, the steps for testing the lithium-ion diffusion coefficient of lithium-rich metal oxides used as positive electrode active materials are as follows: The lithium-rich metal oxide is ground into a powder microelectrode; the powder microelectrode is connected to an electrochemical workstation for coulometric titration. A pulsed current of 20 μA is used, with a titration time of 1 h and an interval of 4 h. (Note: To compare the effects of pulsed current and time, parallel experiments of 10 μA for 10 min can be performed). After obtaining the GITT curve, the lithium-ion diffusion coefficient is calculated using the following formula:

[0195] Among them, D Li V is the lithium-ion diffusion coefficient; I0 ​​is the applied current of 20 μA; V m denoted as ρe, where ρ is the molar volume of the active material, lithium-rich metal oxide; F is the Faraday constant; A is the electrode surface area; n is the number of electrons participating in the reaction, which can also be understood as the charge of lithium ions, i.e., n can be 1; dE / dx is the slope of the coulometric titration curve, i.e., the slope of the open-circuit potential versus Li concentration curve at a certain concentration in the electrode; (dE) / (dt) 1 / 2 ) represents the polarization voltage relative to t 1 / 2 The slope of the curve. For details, please refer to: Xie et al., Solid State Ionics, 2007, 178: 1218–1224; Yang et al., Electrochimica Acta, 2012, 66: 88–93.

[0196] As shown in Tables 1 and 2, Table 1 illustrates the specific parameters for different embodiments and comparative examples, and Table 2 shows the experimental results for different embodiments and comparative examples. Lithium-ion batteries were prepared according to the lithium-rich metal oxides of different embodiments, and the performance of the lithium-ion batteries was tested. The test results are shown in Table 2.

[0197] In Table 1, the lithium-rich metal oxide core refers to the type of lithium-rich metal oxide core selected in the lithium-rich metal oxide, the organic matter refers to the material of the organic layer in the coating layer covering the lithium-rich metal oxide core, the carbonaceous material refers to the type of carbonaceous material in the coating layer, the total content of the coating layer is the ratio of the weight of the coating layer to the weight of the lithium-rich metal oxide, the carbon nanotube content is the ratio of the weight of the carbon nanotubes to the weight of the lithium-rich metal oxide, and Dv 50 Table 1 shows the median particle size of lithium-rich metal oxides, the aspect ratio of carbon nanotubes (the ratio of their length to their outer diameter), the sintering temperature T1 for preparing the lithium-rich metal oxide core, and the sintering temperature T2 for preparing lithium-rich metal oxides using the lithium-rich metal oxide core, organic matter, and carbonaceous materials. In Table 1, CNTs represents carbon nanotubes as the carbonaceous material, P represents asphalt as the organic matter, RB represents rubber as the organic matter, and PVDF represents polyvinylidene fluoride as the organic matter.

[0198] Table 1. Specific parameters of the embodiments and comparative examples.

[0199]

[0200]

[0201] Table 2 Test results of the examples and comparative examples

[0202]

[0203]

[0204] Figure 7 A schematic diagram of a scanning electron microscope showing a lithium-rich metal oxide core without a coating layer. Figure 8 This is a schematic diagram of a scanning electron microscope of a lithium-rich metal oxide core coated with a coating layer, as described in this application.

[0205] Combining Comparative Example 1 and Examples 1-50, the resistivity of lithium-rich metal oxides without coating is much greater than that of lithium-rich metal oxides with coating. Furthermore, when lithium-rich metal oxides without coating are used to make batteries, their first-cycle charging capacity and lithium-ion diffusion coefficient are much lower than those of batteries made from lithium-rich metal oxides with coating.

[0206] Combination Figure 7As shown, the surface of lithium-rich metal oxides contains inert lithium-containing compounds. These compounds affect the diffusion coefficient of lithium ions, the conductivity of lithium-rich metal oxides, and the charging capacity of lithium-ion batteries. Figure 8 As shown, the surface of the lithium-rich metal oxide core is coated with a coating layer, and carbon nanotubes are embedded in the coating layer. Combined with Example 1 and its test data, the performance of the lithium-rich metal oxide with the coating layer is significantly improved.

[0207] In conjunction with Examples 1-9, by reasonably setting the content of the coating layer, both the battery capacity and the lithium-ion diffusion coefficient can be considered. When the content of the coating layer is low, the coating effect is weakened and the battery charging capacity is reduced. When the content of the coating layer is high, it affects the release of lithium ions and reduces the battery charging capacity.

[0208] In conjunction with Examples 10-13, by reasonably setting the content of carbon nanotubes, the conductivity of lithium-rich metal oxides, battery capacity, and lithium-ion diffusion coefficient can be balanced; in conjunction with Example 14, when the content of carbon nanotubes is low, the conductivity of lithium-rich metal oxide powder decreases; in conjunction with Example 15, when the content of carbon nanotubes is high, the charging capacity of the battery decreases.

[0209] In conjunction with Examples 16-19, by reasonably setting the median particle size of lithium-rich metal oxides, the uniformity of coating and capacity of lithium-rich metal oxides can be balanced, which is beneficial to ensuring the capacity of the battery. In conjunction with Example 20, when the median particle size of lithium-rich metal oxides is small, the charging capacity of the battery is reduced. In conjunction with Example 21, when the median particle size of lithium-rich metal oxides is large, the charging capacity of the battery is reduced.

[0210] In conjunction with Examples 22-26, by reasonably setting the aspect ratio of carbon nanotubes, both battery capacity and the conductivity of lithium-rich metal oxides can be considered; in conjunction with Example 27, when the aspect ratio of carbon nanotubes is small, the diffusion coefficient of lithium ions is low; in conjunction with Example 28, when the aspect ratio of carbon nanotubes is large, the charging capacity of the battery decreases.

[0211] In conjunction with Examples 29-33, by reasonably setting the temperature T1, a good balance between battery capacity and lithium-ion diffusion coefficient can be maintained; in conjunction with Example 34, when the primary sintering temperature is low, the battery capacity decreases; in conjunction with Example 35, when the primary sintering temperature is high, the lithium-ion diffusion coefficient decreases.

[0212] In conjunction with Examples 36-41, by reasonably setting the temperature T2, the conductivity and stability of lithium-rich metal oxides, the battery capacity, and the lithium-ion diffusion coefficient can be balanced.

[0213] In conjunction with Examples 42-45, the coating layer of this application can be coated onto the surface of various lithium-rich metal oxide cores to improve battery performance. In conjunction with Examples 46-48, various different carbonaceous materials can be used to coat the lithium-rich metal oxide cores, thereby improving the conductivity of the lithium-rich metal oxides. In conjunction with Examples 49-50, various different organic materials can be used to coat the lithium-rich metal oxide cores.

[0214] Based on Comparative Examples 2-3 and Examples 1-50, it is difficult to simultaneously achieve battery capacity and conductivity of lithium-rich metal oxides by using only carbon nanotubes or organic materials for coating.

[0215] Combining Comparative Examples 4-6 and Examples 1-44, it is difficult to form a coating layer by simply mixing a few materials.

[0216] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A lithium-rich metal oxide characterized in that, The lithium-rich metal oxide core comprises: a coating layer, the coating layer comprising an organic layer and a carbonaceous material, the organic layer coating the lithium-rich metal oxide core, at least part of the carbonaceous material being embedded in the organic layer, and at least part of the carbonaceous material penetrating through the organic layer. The carbonaceous material comprises elemental carbon material.

2. The lithium-rich metal oxide of claim 1, wherein The elemental carbon material comprises one-dimensional carbon material.

3. The lithium-rich metal oxide of claim 2, wherein The one-dimensional carbon material comprises carbon nanotubes.

4. The lithium-rich metal oxide of claim 3, wherein The carbon nanotubes comprise one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.

5. The lithium-rich metal oxide of claim 4, wherein The carbon nanotubes have an aspect ratio of 100:1 to 1000:

1.

6. The lithium-rich metal oxide of claim 4, wherein The carbon nanotubes have an aspect ratio of 200:1 to 400:

1.

7. The lithium-rich metal oxide of claim 6, wherein The mass ratio of the carbon nanotubes to the lithium-rich metal oxide is 0.2% to 2%.

8. The lithium-rich metal oxide of claim 4, wherein The mass ratio of the carbon nanotubes to the lithium-rich metal oxide is 0.5% to 1.5%.

9. The lithium-rich metal oxide of claim 8, wherein, The softening temperature of the organic layer is not more than 450℃.

10. The lithium-rich metal oxide of any one of claims 1-9, wherein, The softening temperature of the organic layer is not more than 300℃.

11. The lithium-rich metal oxide of claim 10, wherein The mass ratio of the coating layer to the lithium-rich metal oxide is 1% to 10%.

12. The lithium-rich metal oxide of any one of claims 1-9, wherein, The median particle size Dv of the lithium-rich metal oxide is 2 μm to 10 μm. 50 is 2 μm to 10 μm.

13. The lithium-rich metal oxide of claim 12, wherein, The median particle size Dv of the lithium-rich metal oxide is 4 μm to 8 μm. 50 is 4 μm to 8 μm.

14. The lithium-rich metal oxide of any one of claims 1-9, wherein, The mass ratio of the coating layer to the lithium-rich metal oxide is 3% to 7%.

15. The lithium-rich metal oxide of claim 14, wherein, The material of the organic layer comprises one or more of rubber, pitch, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene.

16. The lithium-rich metal oxide of any one of claims 1-9, wherein, The material of the lithium-rich metal oxide core includes Li a M n O y , 2≤a≤8, the Li a M n O y includes one or more of Li2M 1 O2, Li2M 2 O3, Li3M 3 O4, Li5M 4 O4, Li6M 5 O4, Li8M 6 O6; M 1 one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Mo; M 2 including one or more of Mn, Sn, Mo, Ru, Ir; M 3 including one or more of V, Nb, Cr, Mo; M 4 including one or more of Fe, Cr, V, Mo; M 5 including one or more of Co, V, Cr, Mo; M 6 including Sn.

17. The lithium-rich metal oxide of claim 16, wherein, The Li a M n O y one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, Li8SnO6.

18. The lithium-rich metal oxide of any one of claims 1-9, wherein, The material of the organic layer comprises one or more of rubber, pitch, and polyvinylidene fluoride.

19. The lithium-rich metal oxide of claim 18, wherein, The lithium-rich metal oxide core comprises:

20. A method of preparing a lithium-rich metal oxide, characterized by, providing a lithium-rich metal oxide core, a carbonaceous material, and an organic material; mixing and processing the lithium-rich metal oxide core, the carbonaceous material, and the organic material to obtain the lithium-rich metal oxide. The processing comprises sintering for 2h to 6h in an inert atmosphere; 21. The method of claim 20, wherein, and / or, The temperature of the processing is not more than 500℃. The inert atmosphere comprises one or more of nitrogen, argon, and helium.

22. The method of claim 21, wherein, The temperature of the processing is not more than 300℃.

23. The method of claim 21, wherein, The method further comprises:

24. The method of claim 20, wherein, sifting the product after the processing to obtain the lithium-rich metal oxide. The carbonaceous material comprises elemental carbon material.

25. The method of claim 20, wherein, The elemental carbon material comprises one-dimensional carbon material.

26. The method of claim 25, wherein, The one-dimensional carbon material comprises carbon nanotubes.

27. The method of claim 26, wherein, The carbon nanotubes comprise one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.

28. The method of claim 27, wherein, The carbon nanotubes have an aspect ratio of 100:1 to 1000:

1.

29. The method of claim 27, wherein, The carbon nanotubes have an aspect ratio of 200:1 to 400:

1.

30. The method of claim 29, wherein, The softening temperature of the organic material is less than the temperature of the processing.

31. The method of any one of claims 20-30, wherein, The softening temperature of the organic material is not more than 450℃.

32. The method of claim 31, wherein, The softening temperature of the organic material is not more than 300℃.

33. The method of claim 32, wherein, The organic material comprises one or more of rubber, pitch, polypropylene, polyethylene, polystyrene, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride, and polytetrafluoroethylene.

34. The method of any one of claims 20-30, wherein, The organic material comprises one or more of rubber, pitch, and polyvinylidene fluoride.

35. The method of claim 34, wherein, The providing a lithium-rich metal oxide core comprises:

36. The method of any one of claims 20-30, wherein, The sintering temperature is 450℃ to 550℃. mixing the Li source and the M n source uniformly in a molar ratio of (a+0.05):1~a:1, and then performing a one-time temperature sintering for 4h~8h in an inert atmosphere, the sintering temperature being 400℃~600℃; wherein the Li source includes one or more of lithium oxide, lithium carbonate, lithium oxalate, lithium acetate, lithium hydroxide, and the M n source includes one or more of oxides, hydroxides, halides, sulfates, carbonates, nitrates, oxalates, acetates, sulfides, nitrides of M n .

37. The method of claim 36, wherein, The inert atmosphere comprises one or more of nitrogen, argon, and helium; 38. The method of claim 36, wherein, ​ subjecting the product of the one-step sintering to airflow crushing to obtain the lithium-rich metal oxide core.

39. A positive electrode sheet characterized by comprising: A lithium-rich metal oxide as defined in any one of claims 1-19.

40. A battery cell, characterized by A positive electrode sheet as defined in claim 39.

41. A battery, comprising: A battery cell as defined in claim 40.

42. An electrical device, comprising: A battery as defined in claim 41.

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