Lithium-rich metal oxide and preparation method thereof, positive pole piece, battery monomer and battery

Abstract

The invention provides a lithium-rich metal oxide and a preparation method thereof, a positive pole piece, a battery monomer and a battery, and belongs to the technical field of batteries. A lithium-rich metal oxide includes a lithium-rich metal oxide core and residual lithium on the surface of the lithium-rich metal oxide core. Wherein based on 100 parts by weight of the lithium-rich metal oxide, the content k of the residual lithium is less than or equal to 0.5%, and the lithium ion diffusion coefficient D of the lithium-rich metal oxide is more than or equal to 1.0 * 10 <-15 > cm < 2 > / s. When the lithium-rich metal oxide is applied to the battery cell, the performance of the battery cell can be improved.

Description

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

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

[0002] With the increasing severity of environmental pollution, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor in its development.

[0003] Lithium-rich metal oxides, as materials for preparing the positive electrode sheets of battery cells, are crucial to the performance of battery cells. Therefore, how to provide a lithium-rich metal oxide to improve the performance of battery cells is a technical problem that needs to be solved urgently.

[0004] Summary of the Invention

[0005] The present application is made in view of the above-mentioned problems, and its purpose is to provide a lithium-rich metal oxide to improve the performance of battery cells.

[0006] In order to achieve the above-mentioned objectives, the present application provides a lithium-rich metal oxide and a preparation method thereof, a positive electrode sheet, a battery cell and a battery.

[0007] In a first aspect, a lithium-rich metal oxide is provided, comprising: a lithium-rich metal oxide core; residual lithium on the surface of the lithium-rich metal oxide core; wherein, based on 100 parts by weight of the lithium-rich metal oxide, the content k of the residual lithium satisfies: k≤0.5wt%, and the lithium ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D≥1.0×10 -15 cm 2 / s.

[0008] The embodiment of the present application provides a lithium-rich metal oxide, including a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium ion content in the lithium-rich metal oxide core is relatively high, and selecting a lithium-rich metal oxide core to prepare a positive electrode material is beneficial to improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the content of residual lithium on the surface of the lithium-rich metal oxide core is k≤0.5wt%, which can reduce the effect of residual lithium on the processing of the positive electrode sheet, and can reduce the effect of residual lithium on the escape of lithium ions from the lithium-rich metal oxide core, thereby reducing the effect on the charging capacity of the battery cell. The diffusion coefficient of lithium ions of lithium-rich metal oxide is D≥1.0×10 -15 cm 2 / s, which is conducive to the release of lithium ions from the lithium-rich metal oxide, and is conducive to improving the charging capacity of the battery cell. Therefore, when the lithium-rich metal oxide of the embodiment of the present application is applied to the battery cell, it is conducive to improving the performance of the battery cell.

[0009] In one possible implementation, k is ≤ 0.1 wt %. This further reduces the residual lithium content on the surface of the lithium-rich metal oxide core, which helps further reduce the impact of residual lithium on the processing of the positive electrode sheet and the impact on the release of lithium ions from the lithium-rich metal oxide, thereby facilitating the preparation of the positive electrode sheet and further improving the charge capacity of the battery cell.

[0010] In one possible implementation, D ≥ 1.0 × 10 -12 cm 2 In this way, the diffusion coefficient of lithium ions in the lithium-rich metal oxide is further increased, which is conducive to the release of lithium ions from the lithium-rich metal oxide, thereby further improving the charging capacity of the battery cell.

[0011] In one possible implementation, the resistivity p of the lithium-rich metal oxide satisfies the following: p ≤ 1 Ω·cm; optionally, p ≤ 0.5 Ω·cm. This lower resistivity of the lithium-rich metal oxide improves its conductivity and facilitates the release of lithium ions from the lithium-rich metal oxide, thereby increasing the charge capacity of the battery cell.

[0012] In a possible implementation, the lithium-rich metal oxide further comprises: a compound Li on the surface of the lithium-rich metal oxide core. z X, where X includes F - 、Cl - 、NO3 - and HSO4 -1 At least one of, z = 1; or, X includes SO4 2- , z=2.

[0013] In the above scheme, the lithium-rich metal oxide includes a compound Li on the surface of the lithium-rich metal oxide core. z X. In one aspect, the compound Li z X has little effect on the processing of the positive electrode sheet, for example, the compound Li z X is less likely to cause the binder polyvinylidene fluoride to denature and thus cause the positive electrode slurry to gel. On the other hand, the compound Li z X has little effect on the release of lithium ions from the lithium-rich metal oxide core, which is beneficial for improving the charging capacity of the battery cell. Therefore, this solution is beneficial for improving the performance of the battery cell.

[0014] In a possible implementation, the lithium-rich metal oxide comprises: the lithium-rich metal oxide core; a coating layer, wherein the coating layer covers the lithium-rich metal oxide core, and the coating layer comprises the compound Li z X.

[0015] In the above scheme, the coating layer covers the lithium-rich metal oxide core, which is beneficial to reduce the risk of the lithium-rich metal oxide core reacting with water and carbon dioxide in the air, thereby improving the stability of the lithium-rich metal oxide. z X is beneficial to improving the diffusion coefficient of lithium ions in the coating layer and the conductivity of the coating layer, thereby improving the charging capacity of the battery cell.

[0016] In one possible implementation, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.01:1 to 0.1:1; optionally, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.02:1 to 0.05:1. This is beneficial for balancing the charging capacity of the battery cell and the production and processing cost of the battery cell.

[0017] In one possible implementation, the compound Li z X is LiF. This is beneficial to further improve the performance of the lithium-rich metal oxide, thereby further improving the charging capacity of the battery cell.

[0018] In one possible implementation, the median particle size D of the lithium-rich metal oxide is v 50 is 2μm to 10μm, and can be optionally 4μm to 8μm. When the median particle size of the lithium-rich metal oxide is within the above range, the path for lithium ions to escape from the lithium-rich metal oxide core is moderate, which is conducive to the escape of lithium ions and is conducive to improving the charging capacity of the battery cell prepared by the lithium-rich metal oxide. Moreover, when the median particle size of the lithium-rich metal oxide is within the above range, the surface activity of the lithium-rich metal oxide can be controlled, the agglomeration between the lithium-rich metal oxide particles or the lithium-rich metal oxide core particles can be suppressed, the particle dispersion is good, and it is conducive to the compound Li z The uniform distribution of X on the surface of the lithium-rich metal oxide core. By reasonably setting the median particle size of the lithium-rich metal oxide, the compound Li of the lithium-rich metal oxide can be taken into account. z The uniformity of the distribution of X and the charge capacity of the battery cell.

[0019] In one possible implementation, the specific surface area of ​​the lithium-rich metal oxide is 0.2 m 2 / g~5m 2 / g, optional 0.5m 2 / g~2m2 / g. This is conducive to further improving the capacity of the battery cell.

[0020] In one 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 Including Li2M 1 O2、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, 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; optionally, the Li a M n O y The lithium-rich metal oxide core may include one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6. In this way, it is convenient to flexibly select a suitable lithium-rich metal oxide core according to actual needs.

[0021] In a second aspect, a method for preparing a lithium-rich metal oxide is provided, comprising: providing an ammonium salt and a lithium-rich metal oxide core; mixing the ammonium salt and the lithium-rich metal oxide core, and treating the mixture to obtain the lithium-rich metal oxide. The lithium-rich metal oxide prepared by this method has high conductivity and stability. When the lithium-rich metal oxide of the present application is used in a battery cell, it is beneficial to improve the performance of the battery cell.

[0022] In one possible implementation, the treatment includes: sintering in an inert atmosphere for 2 hours to 10 hours, optionally 4 hours to 8 hours; and / or, the treatment temperature is 100°C to 600°C, optionally 200°C to 500°C. In this way, by reasonably setting the sintering time and treatment temperature, the ammonium salt reacts with the residual lithium on the surface of the lithium-rich metal oxide core to obtain the compound Li on the surface of the lithium-rich metal oxide core after the reaction is completed. z X; At the same time, it is also beneficial to save costs and reduce the consumption of active lithium in the lithium-rich metal oxide core.

[0023] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate; and optionally, the ammonium salt includes ammonium fluoride. This allows for flexible selection of the type of ammonium salt based on actual conditions.

[0024] In a possible implementation, the molar ratio of the ammonium salt to the lithium-rich metal oxide core is 0.021 to 0.15:1, and can be optionally 0.03:1 to 0.08:1. Thus, by reasonably setting the ratio of the ammonium salt to the lithium-rich metal oxide core, the desired compound Li can be generated. z X, and can also avoid waste caused by excessive ammonium salt content.

[0025] In a possible implementation, the method further includes: performing air flow crushing and screening on the treated product to obtain the lithium-rich metal oxide, thereby facilitating obtaining lithium-rich metal oxide with a suitable particle size.

[0026] In one 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 Including Li2M 1 O2、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, 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; M5 Including one or more of Co, V, Cr, Mo; M 6 Including Sn; optionally, the Li a M n O y The lithium-rich metal oxide core may include one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6. In this way, it is convenient to flexibly select a suitable lithium-rich metal oxide core according to actual needs.

[0027] In a third aspect, a positive electrode plate is provided, comprising the lithium-rich metal oxide in the first aspect and any possible implementation thereof.

[0028] In a fourth aspect, a battery cell is provided, comprising the positive electrode sheet described in the third aspect.

[0029] In a fifth aspect, a battery is provided, comprising the battery cell described in the fourth aspect.

[0030] In a sixth aspect, an electrical device is provided, comprising the battery described in the fifth aspect.

[0031] The embodiment of the present application provides a lithium-rich metal oxide, including a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium ion content in the lithium-rich metal oxide core is relatively high, and selecting a lithium-rich metal oxide core to prepare a positive electrode material is beneficial to improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the content of residual lithium on the surface of the lithium-rich metal oxide core is k≤0.5wt%, which can reduce the effect of residual lithium on the processing of the positive electrode sheet, and can reduce the effect of residual lithium on the escape of lithium ions from the lithium-rich metal oxide core, thereby reducing the effect on the charging capacity of the battery cell. The diffusion coefficient of lithium ions of lithium-rich metal oxide is D≥1.0×10 -15 cm 2 / s, which is conducive to the release of lithium ions from the lithium-rich metal oxide, and is conducive to improving the charging capacity of the battery cell. Therefore, when the lithium-rich metal oxide of the embodiment of the present application is applied to the battery cell, it is conducive to improving the performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of a scanning electron microscope image of a lithium-rich metal oxide according to an embodiment of the present application;

[0033] FIG2 is a schematic diagram of a scanning electron microscope image of a lithium-rich metal oxide core before reaction;

[0034] FIG3 is a schematic diagram of a method for preparing a lithium-rich metal oxide according to an embodiment of the present application;

[0035] FIG4 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0036] FIG5 is a schematic diagram of a battery module according to an embodiment of the present application;

[0037] FIG6 is a schematic diagram of a battery according to an embodiment of the present application;

[0038] FIG. 7 is a schematic diagram of an electrical device according to an embodiment of the present application. DETAILED DESCRIPTION

[0039] Below, with appropriate reference to the accompanying drawings, the embodiments of the lithium-rich metal oxide and its preparation method, battery cell, battery and electrical device of the present application are specifically disclosed in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0040] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0042] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0043] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0044] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0045] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0046] Lithium-ion batteries are widely used in mobile phones, electric vehicles, power stations, and other fields due to their high energy density, high voltage, and long life. The lithium-rich metal oxides in lithium-ion batteries are crucial to their performance, such as charge capacity.

[0047] Lithium-rich metal oxides have a high lithium ion content and are widely used in the preparation of lithium-ion batteries. However, they are less stable and readily react with carbon dioxide and water in the air, forming residual lithium on their surfaces in the form of lithium oxides, hydroxides, and carbonates. The presence of residual lithium affects the performance of lithium-rich metal oxides. Furthermore, when lithium-rich metal oxides are used to prepare battery cells, the presence of residual lithium hinders their preparation and improves their charge capacity, thus affecting their performance.

[0048] In some treatment methods, in order to improve the performance of lithium-rich metal oxides, the corresponding acid is added to the slurry to perform an acid-base neutralization reaction to reduce the content of residual lithium on the surface of the lithium-rich metal oxide. However, the treatment effect of this method is not ideal. On the one hand, the residual lithium content of the lithium-rich metal oxide obtained after treatment is high, and the diffusion coefficient of lithium ions in the lithium-rich metal oxide is low. On the other hand, the uneven distribution of the acid in the slurry can easily cause part of the lithium-rich metal oxide to be over-reacted, resulting in a reduction in the active lithium inside the lithium-rich metal oxide, which has an adverse effect on the performance of the battery cell. The lithium-rich metal oxide obtained by the above treatment method is not conducive to improving the performance of the battery cell.

[0049] In view of this, the present application provides a lithium-rich metal oxide having a low residual lithium content and a high lithium ion diffusion coefficient. The lithium-rich metal oxide of the present application is conducive to improving the performance of battery cells.

[0050] [Lithium-rich metal oxides]

[0051] An embodiment of the present application provides a lithium-rich metal oxide, comprising: a lithium-rich metal oxide core and residual lithium on the surface of the lithium-rich metal oxide core.

[0052] The lithium-rich metal oxide core has a high content of lithium ions. Selecting a lithium-rich metal oxide core to prepare a battery cell is beneficial to improving the charging capacity of the battery cell.

[0053] The material of the lithium-rich metal oxide core is lithium-rich metal oxide, such as lithium ferrite.

[0054] Optionally, the shape of the lithium-rich metal oxide core can be spherical or nearly spherical. The embodiment of the present application does not impose any specific restrictions on the shape of the lithium-rich metal oxide core, as long as the material is a lithium-rich metal oxide.

[0055] Lithium-rich metal oxides include active lithium contained in the core of the lithium-rich metal oxide and residual lithium on the surface of the lithium-rich metal oxide. The active lithium in the lithium-rich metal oxide can be extracted from or embedded in the lithium-rich metal oxide to participate in the charge and discharge process of the battery cell; the residual lithium on the surface of the lithium-rich metal oxide core does not participate in the charge and discharge process of the battery cell.

[0056] Residual lithium refers to the residual lithium on the surface of the lithium-rich metal oxide, which can also be called free lithium. The surface of the lithium-rich metal oxide core can be the surface of the lithium-rich metal oxide core close to the external environment.

[0057] Residual lithium is formed by the reaction of the lithium-rich metal oxide core with water, carbon dioxide, and other substances in the air, such as lithium oxides, lithium hydroxides, and lithium carbonate. For example, residual lithium is Li2CO3, LiOH, and Li2O.

[0058] The residual lithium is located on the surface of the lithium-rich metal oxide core, affecting the lithium ions in the lithium-rich metal oxide core to escape, resulting in a decrease in the performance of the lithium-rich metal oxide and a decrease in the charging capacity of the battery cell. In addition, the residual lithium is highly alkaline. When the lithium-rich metal oxide core is mixed with a binder to form a slurry to prepare a positive electrode sheet, it will affect the performance of the binder, causing the binder, such as polyvinylidene fluoride (PVDF), to denature, affecting the performance of the slurry and the coating of the slurry, thereby affecting the processing of the positive electrode sheet. In an embodiment of the present application, based on 100 parts by weight of lithium-rich metal oxide, the content k of residual lithium satisfies: k≤0.5wt%. This can reduce the effect of residual lithium on the processing of the positive electrode sheet, and can reduce the effect of residual lithium on the escape of lithium ions in the lithium-rich metal oxide core, thereby reducing the effect on the charging capacity of the battery cell, which is beneficial to improving the charging capacity of the battery cell.

[0059] The lithium ion diffusion coefficient refers to the average number of lithium ions passing through a medium per unit area per unit time, which can reflect the penetration rate of lithium ions in the medium. The lithium ion diffusion coefficient of a lithium-rich metal oxide refers to the diffusion coefficient of lithium ions in the lithium-rich metal oxide.

[0060] The lithium ion diffusion coefficient D of lithium-rich metal oxides satisfies: D ≥ 1.0 × 10 -15 cm 2 This is beneficial for the release of lithium ions from the lithium-rich metal oxide, which is beneficial for improving the charging capacity of the battery cell.

[0061] Optionally, the charge capacity of a battery cell may include the initial charge capacity of the battery cell, during which lithium ions are released from the lithium-rich metal oxide during the charging process of the battery cell. For example, the charge capacity of a battery cell may be the ratio of the capacity of the battery cell after the battery cell is fully charged to the mass of the active material in the battery cell.

[0062] Optionally, the lithium-rich metal oxide of the embodiment of the present application can be used as a lithium supplement. For example, the lithium-rich metal oxide is mixed with other positive electrode materials to supplement active lithium.

[0063] Alternatively, the lithium-rich metal oxide of the embodiment of the present application can also be used as an active agent. For example, the lithium-rich metal oxide is mixed with a binder and a conductive agent to form a slurry, which is then coated on the positive electrode current collector to prepare a positive electrode sheet.

[0064] The embodiment of the present application provides a lithium-rich metal oxide, including a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium ion content in the lithium-rich metal oxide core is relatively high, and selecting a lithium-rich metal oxide core to prepare a positive electrode material is beneficial to improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the content of residual lithium on the surface of the lithium-rich metal oxide core is k≤0.5wt%, which can reduce the effect of residual lithium on the processing of the positive electrode sheet, and can reduce the effect of residual lithium on the escape of lithium ions from the lithium-rich metal oxide core, thereby reducing the effect on the charging capacity of the battery cell. The diffusion coefficient of lithium ions of lithium-rich metal oxide is D≥1.0×10 -15 cm 2 / s, which is conducive to the release of lithium ions from the lithium-rich metal oxide, and is conducive to improving the charging capacity of the battery cell. Therefore, when the lithium-rich metal oxide of the present application is applied to the battery cell, it is conducive to improving the performance of the battery cell.

[0065] In some embodiments, k is less than or equal to 0.1 wt %. This further reduces the residual lithium content on the surface of the lithium-rich metal oxide core, thereby further reducing the impact of the residual lithium on the processing of the positive electrode sheet and the impact on the release of lithium ions from the lithium-rich metal oxide. This facilitates the preparation of the positive electrode sheet and further improves the charge capacity of the battery cell.

[0066] In some embodiments, D≥1.0×10 -12 cm 2 In this way, the diffusion coefficient of lithium ions in the lithium-rich metal oxide is further increased, which is conducive to the release of lithium ions from the lithium-rich metal oxide, thereby further improving the charging capacity of the battery cell.

[0067] In some embodiments, the resistivity p of the lithium-rich metal oxide satisfies: p≤1Ω·cm; optionally, p≤0.5Ω·cm.

[0068] The smaller the resistivity of the lithium-rich metal oxide, the higher the conductivity of the lithium-rich metal oxide, and the more conducive it is for lithium ions to escape from the lithium-rich metal oxide.

[0069] In the above embodiment, the resistivity p of the lithium-rich metal oxide is less than or equal to 1Ω·cm, which is beneficial to improving the conductivity of the lithium-rich metal oxide and the charging capacity of the battery cell.

[0070] The resistivity p of the lithium-rich metal oxide is ≤0.5Ω·cm, which is beneficial to further improve the conductivity of the lithium-rich metal oxide and the charging capacity of the battery cell.

[0071] FIG1 is a schematic diagram of a scanning electron microscope of a lithium-rich metal oxide according to an embodiment of the present invention. In some embodiments, as shown in FIG1 , the lithium-rich metal oxide further comprises: a compound Li on the surface of the lithium-rich metal oxide core; z X, where X includes F - 、Cl - 、NO3 - and HSO4 -1 At least one of, z = 1; or, X includes SO4 2- , z = 2. For example, the compound Li z X is LiF, LiCl, LiNO3, or Li2SO4.

[0072] Figure 2 is a schematic diagram of a scanning electron microscope before the reaction of the lithium-rich metal oxide core. As shown in Figure 2, a compound Li is generated on the surface of the lithium-rich oxide core. z Before X, there is a lot of residual lithium on the surface of the lithium-rich metal oxide core.

[0073] Compound Li z X can be a product generated by the reaction of ammonium salt and residual lithium. After the reaction occurs, the residual lithium is converted into compound Li z X. Compared with residual lithium, compound Li z X will not react with the binder PVDF to cause the binder to denature; the compound Li z X has high conductivity, and lithium ions can be transported from the compound Li z X is removed. Therefore, by converting the residual lithium on the surface of the lithium-rich metal oxide core into the compound Li z X is beneficial to improving the performance of lithium-rich metal oxides, facilitating the preparation of positive electrode sheets and improving the charging capacity of battery cells.

[0074] Optionally, as shown in FIG1 and FIG2 , after the ammonium salt reacts with the residual lithium, the residual lithium on the surface of the lithium-rich metal oxide core is greatly reduced.

[0075] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate.

[0076] In the above embodiment, the lithium-rich metal oxide includes a compound Li on the surface of the lithium-rich metal oxide core. z X. In one aspect, the compound Li z X has little effect on the processing of the positive electrode. On the other hand, the compound Li z X has little effect on the release of lithium ions from the lithium-rich metal oxide core, which is beneficial for improving the charging capacity of the battery cell. Therefore, this solution is beneficial for improving the performance of the battery cell.

[0077] In some embodiments, the lithium-rich metal oxide includes a lithium-rich metal oxide core and a coating layer.

[0078] The coating layer covers the lithium-rich metal oxide core, and the coating layer includes the compound Li z X.

[0079] Before the lithium-rich metal oxide is prepared by the lithium-rich metal oxide core and the ammonium salt, residual lithium exists on the surface of the lithium-rich metal oxide core. After the residual lithium reacts with the ammonium salt, at least part of the residual lithium is converted into the compound Li z X. That is, after the residual lithium reacts with the ammonium salt, there is no residual lithium on the surface of the lithium-rich metal oxide core, that is, the residual lithium is completely converted into the compound Li z X; or, after the residual lithium reacts with the ammonium salt, residual lithium exists on the surface of the lithium-rich metal oxide core, that is, part of the residual lithium is converted into the compound Li z X, the remaining residual lithium still exists on the surface of the lithium-rich metal oxide core.

[0080] Optionally, the coating layer further includes residual lithium.

[0081] Optionally, the coating layer covers a portion of the lithium-rich metal oxide core and is formed at the location of residual lithium before the reaction.

[0082] Optionally, the coating layer covers the entire lithium-rich metal oxide core, which is beneficial to further improve the stability of the lithium-rich metal oxide.

[0083] In the above embodiment, the coating layer covers the lithium-rich metal oxide core, which is beneficial to reducing the risk of the lithium-rich metal oxide core reacting with water and carbon dioxide in the air, thereby improving the stability of the lithium-rich metal oxide. z X is beneficial to improving the diffusion coefficient of lithium ions in the coating layer and the conductivity of the coating layer, thereby improving the charging capacity of the battery cell.

[0084] In some embodiments, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.01:1 to 0.1:1; optionally, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.02:1 to 0.05:1.

[0085] In the compound Li z When the molar ratio of X to the lithium-rich metal oxide core is not less than 0.01:1, the compound Li z The content of X helps to further improve the ion conductivity of the lithium-rich metal oxide and the charging capacity of the battery cell.

[0086] In the compound Li z When the molar ratio of X to the lithium-rich metal oxide core is not higher than 0.1:1, the preparation of the compound Li z X's raw material demand is beneficial to saving costs; it can also control Li z X is the coating thickness of lithium-rich metal oxide.

[0087] In the above embodiment, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.01:1 to 0.1:1, which is beneficial for improving the charging capacity of the battery cell while taking into account the production and processing costs of the battery cell.

[0088] Alternatively, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.02:1 to 0.05:1. This helps to further balance the charging capacity of the battery cell and the production and processing cost of the battery cell.

[0089] In some embodiments, the compound Li z X is LiF. This is beneficial to further improve the performance of the lithium-rich metal oxide, thereby further improving the charging capacity of the battery cell.

[0090] In some embodiments, the median particle size D of the lithium-rich metal oxide is v 50 is 2μm~10μm, and can be optionally 4μm~8μm.

[0091] Median particle size D v 50 can refer to the particle size corresponding to when the cumulative volume distribution percentage of a sample reaches 50%.

[0092] Median particle size D of lithium-rich metal oxides v 50 is related to the median particle size of the lithium-rich metal oxide core. The larger the median particle size of the lithium-rich metal oxide core, the larger the median particle size D of the lithium-rich metal oxide. v The larger the value of 50 is, the smaller the median particle size of the lithium-rich metal oxide core is. v 50 is smaller.

[0093] If the median particle size of the lithium-rich metal oxide is too large, the path for lithium ions to escape from the lithium-rich metal oxide core is too long, which is not conducive to the escape of lithium ions and affects the charging capacity of the battery monomer prepared by 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, the lithium-rich metal oxide particles or the lithium-rich metal oxide core particles are easy to agglomerate, and the particle dispersion is poor, which is not conducive to the uniform generation of compound Li on the surface of the lithium-rich metal oxide core. z X.

[0094] In the above embodiment, the median particle size D of the lithium-rich metal oxide is v 50 is 2μm~10μm, the path of lithium ions escaping from the lithium-rich metal oxide core is moderate, which is conducive to the escape of lithium ions and the improvement of the charging capacity of the battery monomer prepared by the lithium-rich metal oxide; in addition, it is also conducive to controlling the surface activity of the lithium-rich metal oxide, inhibiting the agglomeration between the lithium-rich metal oxide particles or the lithium-rich metal oxide core particles, and the particle dispersion is good, which is conducive to the compound Li z The uniform distribution of X on the surface of the lithium-rich metal oxide core. By reasonably setting the median particle size of the lithium-rich metal oxide, the compound Li of the lithium-rich metal oxide can be taken into account. z The uniformity of X distribution and the charge capacity of the battery cell.

[0095] In some embodiments, the specific surface area of ​​the lithium-rich metal oxide is 0.2 m 2 / g~5m 2 / g, optional 0.5m 2 / g~2m 2 / g. This is conducive to further improving the capacity of the battery cell.

[0096] In some embodiments, the median particle size of the lithium-rich metal oxide is 4 μm to 8 μm, and the specific surface area is 0.5 m 2 / g~2m 2 / g. This is beneficial to improving the charging capacity of the battery cell.

[0097] In some embodiments, the lithium-rich metal oxide core material 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 5 O4、Li8M 6 One or more of O6; M 1 Including 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 5Including one or more of Co, V, Cr, Mo; M 6 including Sn; optionally, Li a M n O y The lithium-rich metal oxide core may include one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6. In this way, it is convenient to flexibly select a suitable lithium-rich metal oxide core according to actual needs.

[0098] The above describes the embodiment of the lithium-rich metal oxide of the present application. The following details the embodiment of the method for preparing the lithium-rich metal oxide. For the parts not described in the embodiment of the method for preparing the lithium-rich metal oxide, reference can be made to the relevant description of the embodiment of the lithium-rich metal oxide.

[0099] [Preparation method of lithium-rich metal oxide]

[0100] FIG3 is a schematic diagram of a method for preparing a lithium-rich metal oxide according to an embodiment of the present application. As shown in FIG3 , method 100 includes steps 110 and 120 .

[0101] Step 110 , providing an ammonium salt and a lithium-rich metal oxide core.

[0102] In step 120 , the ammonium salt and the lithium-rich metal oxide core are mixed and treated to obtain a lithium-rich metal oxide.

[0103] Since the lithium-rich metal oxide core easily reacts with water, carbon dioxide, etc. in the air, residual lithium exists on the surface of the lithium-rich metal oxide core, such as Li2CO3, LiOH, Li2O, etc. Ammonium salts can react with the residual lithium, and after the reaction, at least part of the residual lithium is converted into the compound Li z X.

[0104] After the ammonium salt reacts with the residual lithium on the surface of the lithium-rich metal oxide core, the residual lithium content on the surface of the lithium-rich metal oxide core decreases, for example, to less than 0.5 wt % or even 0.1 wt % of the weight of the lithium-rich metal oxide.

[0105] Compared with residual lithium, compound Li z X has excellent electrical conductivity, has little effect on the release of lithium ions from lithium-rich metal oxides, and has little effect on the adhesive PVDF. In addition, at least part of the surface of the lithium-rich metal oxide is compound Li z X or compound Li z X and residual lithium are not likely to react with water and carbon dioxide in the air.

[0106] In the embodiment of the present application, the lithium-rich metal oxide prepared by method 100 has high conductivity and stability. When the lithium-rich metal oxide of the present application is applied to a battery cell, it is beneficial to improve the performance of the battery cell.

[0107] In some embodiments, the treatment includes: sintering in an inert atmosphere for 2 hours to 10 hours, optionally 4 hours to 8 hours; and / or, the treatment temperature is 100° C. to 600° C., optionally 200° C. to 500° C.

[0108] Optionally, the inert atmosphere includes one or more of nitrogen, argon and helium, so that it is convenient to select a suitable inert gas according to actual needs.

[0109] When the sintering time in an inert atmosphere is not less than 2 hours, it is beneficial for the ammonium salt to fully react with the residual lithium on the surface of the lithium-rich metal oxide core; when the sintering time in an inert atmosphere is not more than 10 hours, the sintering time is appropriate, which is beneficial to reducing costs.

[0110] When the treatment temperature is not less than 100°C, it is beneficial for the ammonium salt to fully react with the residual lithium on the surface of the lithium-rich metal oxide core; when the treatment temperature is not more than 600°C, it is beneficial for maintaining the content of active lithium in the lithium-rich metal oxide core.

[0111] Optionally, sintering in an inert atmosphere for 4 to 8 hours can further take into account the reaction between the ammonium salt and the residual lithium and the production cost.

[0112] Optionally, the treatment temperature is 200° C. to 500° C., which can further take into account the reaction between the ammonium salt and the residual lithium and the content of active lithium in the lithium-rich metal oxide core.

[0113] In the above embodiment, by reasonably setting the sintering time and the treatment temperature, the ammonium salt reacts with the lithium-rich metal oxide core to obtain the compound Li on the surface of the lithium-rich metal oxide core after the reaction is completed. z X; At the same time, it is also beneficial to save costs and reduce the consumption of active lithium in the lithium-rich metal oxide core.

[0114] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate; and optionally, the ammonium salt includes ammonium fluoride. This allows for flexible selection of the type of ammonium salt based on actual conditions.

[0115] In some embodiments, the molar ratio of the ammonium salt to the lithium-rich metal oxide core is 0.021 to 0.15:1, and can optionally be 0.03:1 to 0.08:1. Thus, by properly setting the ratio of the ammonium salt to the lithium-rich metal oxide core, the desired compound LizX can be produced while avoiding waste caused by excessive ammonium salt content.

[0116] In some embodiments, the method 100 further includes: performing air flow crushing and screening on the treated product to obtain lithium-rich metal oxide, thereby facilitating obtaining lithium-rich metal oxide with a suitable particle size.

[0117] In some embodiments, the lithium-rich metal oxide core material 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 5 O4、Li8M 6 One or more of O6; M 1 Including 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; optionally, Li a M n O y The lithium-rich metal oxide core may include one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6. In this way, it is convenient to flexibly select a suitable lithium-rich metal oxide core according to actual needs.

[0118] In some embodiments, the temperature of the above treatment does not exceed 500° C., and optionally, the above temperature does not exceed 300° C. In this way, a lithium-rich metal oxide 1 having a uniform and dense coating layer can be obtained at a lower temperature.

[0119] In some embodiments, providing a lithium-rich metal oxide core comprises: n The sources are mixed uniformly in a molar ratio of (a+0.05):1 to a:1 and then sintered in an inert atmosphere for 4h to 8h at a sintering temperature of 400°C to 600°C; wherein the Li source includes one or more of lithium oxide, lithium carbonate, lithium oxalate, lithium acetate, and lithium hydroxide, and M n Sources include M nOne or more of the oxides, hydroxides, halides, sulfates, carbonates, nitrates, oxalates, acetates, sulfides, and nitrides; optionally, the sintering temperature is 450°C to 550°C; optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium; the product of the primary sintering is subjected to air flow crushing to obtain a lithium-rich metal oxide core. In this way, it is easy to prepare a suitable lithium-rich metal oxide core, so as to facilitate the subsequent preparation of lithium-rich metal oxides. In addition, this method prepares the lithium-rich metal oxide core at a lower sintering temperature, which is beneficial to reduce costs and also helps to reduce the volatilization of active lithium.

[0120] [Positive electrode]

[0121] The present application provides a positive electrode plate, comprising the lithium-rich metal oxide in any one of the embodiments.

[0122] [Battery Cell]

[0123] The present application provides a battery cell, comprising the positive electrode sheet in the above embodiment.

[0124] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape.

[0125] FIG4 is a schematic diagram of a battery cell according to an embodiment of the present application. As shown in FIG4 , the battery cell 4 includes a housing 31 , a cover plate 32 , and an electrode assembly 33 disposed in the housing 31 .

[0126] The electrode assembly 33 can be made of the positive electrode sheet, the negative electrode sheet and the separator of the present application through a winding process or a lamination process.

[0127] Optionally, the battery cell 3 further includes an electrolyte. The electrolyte can be solid, semi-solid, or liquid, and this embodiment of the application does not impose any specific limitation on this.

[0128] In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in a battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0129] Figure 5 is a schematic diagram of a battery module according to one embodiment of the present application. Referring to Figure 5 , within a battery module 4, multiple battery cells 3 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple battery cells 3 may be secured together using fasteners.

[0130] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 3 are accommodated in the accommodation space.

[0131] [Battery]

[0132] The present application provides a battery, comprising the battery cell described in the above embodiment.

[0133] Figure 6 is a schematic diagram of a battery according to an embodiment of the present application. As shown in Figure 6 , the present application provides a battery 5 comprising a battery cell 3 according to any of the above embodiments.

[0134] The battery cells 3 can be directly assembled into the battery 5 , or they can be assembled into battery modules first, and then multiple battery modules can be assembled into the battery 5 .

[0135] [Electrical devices]

[0136] The present application provides an electrical device, comprising the battery described in the above embodiment.

[0137] Figure 7 is a schematic diagram of an electric device according to an embodiment of the present application. As shown in Figure 7 , the present application provides an electric device 6 including the battery 5 according to the above embodiment.

[0138] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0139] [Example]

[0140] Example 1

[0141] In Example 1, the lithium-rich metal oxide core reacts with an ammonium salt at 350° C. for 6 hours to obtain a lithium-rich metal oxide, wherein the lithium-rich metal oxide core is Li5FeO4, and the molar ratio m1 of the ammonium salt NH4F to the lithium-rich metal oxide core Li5FeO4 is 0.05:1.

[0142] Compound Li on the surface of lithium-rich metal oxide core z X is LiF, the molar ratio m2 of the compound LiF to the lithium-rich metal oxide core Li5FeO4 is 0.03:1, the content k of residual lithium on the surface of the lithium-rich metal oxide core is 0.021wt%, and the diffusion coefficient D of lithium ions in the lithium-rich metal oxide is 2.8×10 -11 cm 2 / s, the resistivity p of the lithium-rich metal oxide is 0.22Ω·cm, and the specific surface area s of the lithium-rich metal oxide is 1.215m 2 / g.

[0143] Examples 2-5

[0144] The difference between Example 2-5 and Example 1 is that the molar ratio m1 of the ammonium salt NH4F to the lithium-rich metal oxide core Li5FeO4 is different.

[0145] Correspondingly, the residual lithium content k on the surface of the lithium-rich metal oxide core, the lithium ion diffusion coefficient D of the lithium-rich metal oxide, the resistivity p of the lithium-rich metal oxide, and the molar ratio m2 of the compound LiF to the lithium-rich metal oxide core Li5FeO4 also change accordingly. Specific parameters can be found in Table 1.

[0146] Examples 6-9

[0147] The difference between Examples 6-9 and Example 1 is that the reaction temperature T1 of the ammonium salt NH4F and the lithium-rich metal oxide core Li5FeO4 is different.

[0148] Correspondingly, the residual lithium content k on the surface of the lithium-rich metal oxide core, the lithium ion diffusion coefficient D of the lithium-rich metal oxide, the resistivity p of the lithium-rich metal oxide, and the molar ratio m2 of the compound LiF to the lithium-rich metal oxide core Li5FeO4 also change accordingly. Specific parameters can be found in Table 1.

[0149] Examples 10-13

[0150] The difference between Examples 10-13 and Example 1 is that the reaction time L of the ammonium salt NH4F and the lithium-rich metal oxide core Li5FeO4 is different.

[0151] Correspondingly, the residual lithium content k on the surface of the lithium-rich metal oxide core, the lithium ion diffusion coefficient D of the lithium-rich metal oxide, the resistivity p of the lithium-rich metal oxide, and the molar ratio m2 of the compound LiF to the lithium-rich metal oxide core Li5FeO4 also change accordingly. Specific parameters can be found in Table 1.

[0152] Examples 14-17

[0153] The difference between Examples 14-17 and Example 1 is that the median particle size D of the lithium-rich metal oxide is v 50 different.

[0154] Correspondingly, the residual lithium content k on the surface of the lithium-rich metal oxide core, the lithium ion diffusion coefficient D of the lithium-rich metal oxide, and the specific surface area s of the lithium-rich metal oxide also change accordingly. Specific parameters can be found in Table 1.

[0155] Examples 18-21

[0156] The difference between Examples 18-21 and Example 1 is that the ammonium salts are different.

[0157] Correspondingly, the diffusion coefficient D of lithium ions in the lithium-rich metal oxide also changes accordingly. Specific parameters can be found in Table 1.

[0158] Example 22

[0159] The difference between Example 22 and Example 1 is that the molar ratio m1 of the ammonium salt NH4F and the lithium-rich metal oxide core Li5FeO4 and the reaction temperature T1 are different.

[0160] Example 23

[0161] The difference between Example 23 and Example 1 is that the molar ratio m1 of the ammonium salt NH4F and the lithium-rich metal oxide core Li5FeO4, the reaction temperature T1 and the reaction time L are different.

[0162] Example 24

[0163] The difference between Example 24 and Example 1 is that the molar ratio m1 of ammonium salt NH4F and lithium-rich metal oxide core Li5FeO4, the reaction time L, the median particle size D of lithium-rich metal oxide v 50 different.

[0164] Example 25

[0165] The difference between Example 25 and Example 1 is that the reaction temperature T1 of the ammonium salt NH4F and the lithium-rich metal oxide core Li5FeO4, the median particle size D of the lithium-rich metal oxide v 50 different.

[0166] Examples 26-29

[0167] The difference between Examples 26-29 and Example 1 is that the materials of the lithium-rich metal oxide core are different, wherein the materials of the lithium-rich metal oxide core are: Li6CoO4, Li2CuO2, Li2NiO2, Li3NbO4.

[0168] Comparative Example 1

[0169] The difference between Comparative Example 1 and Example 1 is that the lithium-rich metal oxide core Li5FeO4 is not reacted with ammonium salt to prepare the lithium-rich metal oxide, and the lithium-rich metal oxide core Li5FeO4 is used as the lithium-rich metal oxide.

[0170] Comparative Examples 2-5

[0171] The difference between Comparative Examples 2-5 and Comparative Example 1 is that the lithium-rich metal oxide cores are different.

[0172] [Preparation method of lithium-rich metal oxide]

[0173] The lithium-rich metal oxide core and the ammonium salt are mixed evenly, and then sintered in an inert atmosphere. After sintering, the mixture is subjected to air flow crushing and sieving to obtain the lithium-rich metal oxide.

[0174] [Residual lithium content test]

[0175] The lithium-rich metal oxide is titrated with a standard hydrochloric acid solution to measure the residual lithium content of the lithium-rich metal oxide.

[0176] The residual lithium on the surface of a lithium-rich metal oxide, including lithium carbonate and lithium hydroxide, is used as an example. Add m1g of the lithium-rich metal oxide to bmL of deionized water and stir at 200 rpm for 5 minutes. The lithium-rich metal oxide is then titrated with a standard hydrochloric acid solution (hydrochloric acid concentration c mol / L) (hydrochloric acid reacts with the lithium carbonate and lithium hydroxide in the lithium-rich metal oxide). Using a composite pH electrode as the indicator electrode, the potential jump produced is used to determine the titration endpoint, and the residual lithium content of the lithium-rich metal oxide is calculated.

[0177] During the titration reaction, potential jump points E1 and E2 are generated. At potential jump point E1, lithium hydroxide reacts with hydrochloric acid to form lithium chloride, and lithium carbonate reacts with hydrochloric acid to form lithium chloride and lithium bicarbonate. The volume of hydrochloric acid consumed at this time is V1. At potential jump point E2, lithium bicarbonate reacts with hydrochloric acid to form lithium chloride, and the volume of hydrochloric acid consumed at this time is V2. Based on the consumed volumes of hydrochloric acid V1 and V2, the residual lithium content can be calculated.

[0178] [Compound Li z X's test]

[0179] The residual lithium content of mg lithium-rich metal oxide was tested. Based on the mass of the lithium-rich metal oxide, the mass fraction of residual lithium was measured to be h%, and the molar number of lithium ions in the residual lithium was obtained as (h×m) / M Li (M Li is the relative atomic mass of lithium).

[0180] Take mg of lithium-rich metal oxide and test it by inductively coupled plasma atomic emission spectrometry (ICP) to obtain the total lithium ion mass fraction of k%, metal M n The mass fraction of is t%, and the total molar number of lithium ions is (k×m) / M Li , Metal M n The number of moles is (t×m) / M n (M n Metal element M n relative atomic mass).

[0181] LizX and Li-rich metal oxide core Li a M n O y The molar ratio f = [(k × m) / M Li -(h×m) / M Li-(t×m)×a / M n ] / [(t×m) / M Li ), and then we get f=[(kh)×M n ] / (M Li ×t)-a.

[0182] Inductively coupled plasma atomic emission spectrometry (ICP) testing can be performed using an inductively coupled plasma atomic emission spectrometer (e.g., the ICAP7400 from Thermo Fisher Scientific, USA). An exemplary testing method is as follows: 2 g of a metal oxide material is digested in an acid solution (e.g., aqua regia). The digestion can be performed under stirring (e.g., mechanical stirring or microwave stirring) for 30 minutes. The digested solution is then added to the ICAP7400 spectrometer to quantitatively analyze the chemical composition of the metal oxide material.

[0183] [Specific surface area test]

[0184] The BET specific surface area of ​​a positive electrode active material is well known in the art and can be measured using instruments and methods known in the art, such as the gas adsorption method, according to the GB / T19587-2017 test standard. Specifically, a lithium-rich metal oxide material is sampled, and the sample tube is immersed in liquid nitrogen at -196°C. The amount of nitrogen adsorbed on the solid surface at different pressures is measured at a relative pressure of 0.05-0.30. The monolayer adsorption of the sample is calculated based on the BET multilayer adsorption theory and its formula, thereby calculating the specific surface area of ​​the lithium-rich metal oxide material.

[0185] [The median particle size D of lithium-rich metal oxides v 50 tests]

[0186] The median particle size D of lithium-rich metal oxides v 50 can be measured with a laser particle size analyzer according to GB / T 19077-2016 particle size distribution laser diffraction method.

[0187] [Testing the resistivity of lithium-rich metal oxides]

[0188] The powder of the lithium-rich metal oxide was dried, and an appropriate amount of powder was weighed. The powder resistivity of the sample was then measured using a powder resistivity tester (ST2722 digital four-probe tester, manufactured by Suzhou Jingge Electronics Co., Ltd.) in accordance with GB / T 30835-2014 "Carbon-composite lithium iron phosphate lithium-rich metal oxide for lithium-ion batteries" at a test pressure of 20 MPa.

[0189] [Test of lithium ion diffusion coefficient]

[0190] The diffusion coefficient of lithium ions can be measured using conventional methods in the art such as the CV method, EIS method, GITT method, and PITT method, and calculated based on Fick's first and second laws.

[0191] Using the GITT method as an example, the steps for measuring the lithium ion diffusion coefficient of a lithium-rich metal oxide used as a cathode active material are as follows: Grind the lithium-rich metal oxide into a powder microelectrode; connect the powder microelectrode to an electrochemical workstation and perform a coulometric titration. The titration is performed with a pulse current of 20 μA for 1 hour and a rest period of 4 hours. (Note: To compare the effects of pulse current and time, a parallel experiment with 10 μA and 10 minutes can be performed.) After obtaining the GITT curve, the lithium ion diffusion coefficient is calculated using the following formula:

[0192] Where D is the lithium ion diffusion coefficient; I0 ​​is the applied current 20μA; V m 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 number of lithium ions, that is, n can be 1, dE / dx is the slope of the coulometric titration curve, that is, the slope of the open circuit potential at a certain concentration on the Li concentration curve in the electrode; (dE) / (dt 1 / 2 ) is the polarization voltage versus 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.

[0193] [Preparation of lithium-ion batteries]

[0194] Preparation of the positive electrode sheet: Lithium-rich metal oxide, binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 97:2:1. The mixture is thoroughly stirred and mixed to form a positive electrode slurry. The slurry is evenly coated on the positive electrode current collector aluminum foil. The positive electrode sheet is then dried, cold-pressed, and slit. In the preparation of this positive electrode sheet, the lithium-rich metal oxide is used as the active material, and no other active materials are added.

[0195] Preparation of negative electrode sheets: Dissolve the negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) in deionized water at a mass ratio of 96:1.5:1.5:1.0, stir and mix thoroughly to prepare a negative electrode slurry; coat the negative electrode slurry on the negative electrode current collector copper foil, and then dry, cold press, and cut to obtain the negative electrode sheet.

[0196] Isolation film: polypropylene film.

[0197] Preparation of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and LiPF6 was uniformly dissolved in the above solution to obtain an electrolyte. The concentration of LiPF6 in the electrolyte was 1 mol / L.

[0198] Preparation of lithium-ion batteries: The positive electrode sheet, separator, and negative electrode sheet are stacked and wound in order to obtain an electrode assembly; the electrode assembly is placed in an outer package, and the electrolyte prepared above is added. After packaging, standing, formation, aging and other processes, a lithium-ion battery is obtained.

[0199] [Testing the initial charge capacity of lithium-ion batteries]

[0200] The assembled lithium-ion battery was charged at a constant current of 0.1C to 4.25V, left to stand for 5 minutes, and the first-cycle charging capacity of the lithium-ion battery was recorded. The first-cycle charging capacity of the lithium-ion battery was obtained by dividing the first-cycle charging capacity of the battery by the mass of the lithium-rich metal oxide.

[0201] Table 1 Specific parameters and experimental results of the embodiments and comparative examples

[0202] As shown in Table 1, Table 1 shows the specific parameters and experimental results of different embodiments and comparative examples. In Table 1, k represents the content of residual lithium on the surface of the lithium-rich metal oxide core in the lithium-rich metal oxide based on 100 parts of the lithium-rich metal oxide; D represents the diffusion coefficient of lithium ions; p represents the resistivity of the lithium-rich metal oxide; T1 represents the reaction temperature of the ammonium salt and the residual lithium; L represents the reaction time of the ammonium salt and the residual lithium; Li z X represents the compound on the surface of the lithium-rich metal oxide core; m1 represents the molar ratio of the ammonium salt to the lithium-rich metal oxide core; m2 represents the compound Li z The molar ratio of X to the lithium-rich metal oxide core; D v 50 represents the median particle size of the lithium-rich metal oxide; s represents the specific surface area of ​​the lithium-rich metal oxide; and Q represents the first cycle charging capacity of the lithium-ion battery.

[0203] As shown in combination with Examples 1-25 and Comparative Example 1, the content of residual lithium in Comparative Example 1 is relatively high, and the charging capacity of the lithium ion battery in Comparative Example 1 is significantly lower than the charging capacity of the lithium ion battery in Examples 1-25 of the present application; as shown in combination with Examples 26-29 and Comparative Examples 2-5, the content of residual lithium in Comparative Examples 2-5 is relatively high, and the charging capacity of the lithium ion battery in Comparative Examples 2-5 is significantly lower than the charging capacity of the lithium ion battery in Examples 26-29 of the present application. As shown in combination with Examples 1-5 and Examples 22-24, a reasonable setting of the molar ratio of ammonium salt to lithium-rich metal oxide core is conducive to obtaining a more suitable lithium-containing compound Li z The molar ratio of X to the lithium-rich metal oxide core is used to reduce the residual lithium content on the surface of the lithium-rich metal oxide core, increase the diffusion coefficient of lithium ions, reduce the resistivity of the lithium-rich metal oxide, and improve the charging capacity of the lithium-ion battery monomer. In combination with Examples 6-9, Examples 10-13 and Examples 23-24, the reaction temperature and reaction time of the ammonium salt and the lithium-rich metal oxide core are reasonably set, which is conducive to obtaining a more suitable lithium-containing compound Li z The molar ratio of X to the lithium-rich metal oxide core is beneficial to reducing the content of residual lithium on the surface of the lithium-rich metal oxide core, increasing the diffusion coefficient of lithium ions, reducing the resistivity of the lithium-rich metal oxide, and improving the charging capacity of the lithium-ion battery cell. In combination with Examples 14-17 and Examples 24-25, reasonably setting the median particle size of the lithium-rich metal oxide is beneficial to obtaining a suitable specific surface area of ​​the lithium-rich metal oxide, reducing the content of residual lithium on the surface of the lithium-rich metal oxide core, increasing the diffusion coefficient of lithium ions, and improving the charging capacity of the lithium-ion battery cell. In combination with Examples 18-21, different ammonium salts can react with the residual lithium on the surface of the lithium-rich metal oxide core, thereby generating corresponding compounds on the surface of the lithium-rich metal oxide core, which is beneficial to improving the charging capacity of the lithium-ion battery. In combination with Examples 26-29, the lithium-rich metal oxide core can be made of a variety of different materials.

[0204] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium-rich metal oxide, characterized in that include: Lithium-rich metal oxide core; Residual lithium on the surface of the lithium-rich metal oxide core; Wherein, based on 100 parts by weight of the lithium-rich metal oxide, the residual lithium content k satisfies: k≤0.5wt%, and the lithium ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D≥1.0×10 -15 cm 2 / s.

2. The lithium-rich metal oxide according to claim 1, characterized in that k≤0.1wt%.

3. The lithium-rich metal oxide according to claim 1 or 2, characterized in that D≥1.0×10 -12 cm 2 / s。 4. The lithium-rich metal oxide according to any one of claims 1 to 3, characterized in that The resistivity p of the lithium-rich metal oxide satisfies: p≤1Ω·cm; optionally, p≤0.5Ω·cm.

5. The lithium-rich metal oxide according to any one of claims 1 to 4, characterized in that The lithium-rich metal oxide further comprises: a compound Li z X, where X includes F - , Cl - NO3 - and HSO4 -1 At least one of, z = 1; or, X includes SO4 2- , z=2.

6. The lithium-rich metal oxide according to claim 5, characterized in that The lithium-rich metal oxide comprises: The lithium-rich metal oxide core; The coating layer covers the lithium-rich metal oxide core, and the coating layer includes the compound Li z X.

7. The lithium-rich metal oxide according to claim 5 or 6, characterized in that The compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.01:1 to 0.1:1; optionally, the compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.02:1 to 0.05:

1.

8. The lithium-rich metal oxide according to any one of claims 5 to 7, characterized in that The compound Li z X is LiF.

9. The lithium-rich metal oxide according to any one of claims 1 to 8, characterized in that The median particle size D of the lithium-rich metal oxide v 50 is 2μm~10μm, and can be optionally 4μm~8μm.

10. The lithium-rich metal oxide according to any one of claims 1 to 9, characterized in that The specific surface area of ​​the lithium-rich metal oxide is 0.2 m 2 / g~5m 2 / g, optional 0.5m 2 / g~2m 2 / g.

11. The lithium-rich metal oxide according to any one of claims 1 to 10, characterized in that The lithium-rich metal oxide core material includes Li a M n O y , 2≤a≤8, the Li a M n O y Including Li2M 1 O2、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 Including 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 Including one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6.

12. A method for preparing a lithium-rich metal oxide, characterized in that: include: providing an ammonium salt and a lithium-rich metal oxide core; The ammonium salt and the lithium-rich metal oxide core are mixed and treated to obtain the lithium-rich metal oxide.

13. The method according to claim 12, characterized in that The treatment comprises: sintering in an inert atmosphere for 2 hours to 10 hours, optionally 4 hours to 8 hours; and / or, The treatment temperature is 100°C to 600°C, and can be optionally 200°C to 500°C.

14. The method according to claim 12 or 13, characterized in that The ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate and ammonium bisulfate; optionally, the ammonium salt includes ammonium fluoride.

15. The method according to any one of claims 12 to 14, characterized in that: The molar ratio of the ammonium salt to the lithium-rich metal oxide core is 0.02 to 0.15:1, and can be optionally 0.03:1 to 0.08:

1.

16. The method according to any one of claims 12 to 15, characterized in that: The method further comprises: The product after the treatment is subjected to air flow crushing and screening to obtain the lithium-rich metal oxide.

17. The method according to any one of claims 12 to 16, characterized in that: The lithium-rich metal oxide core material includes Li a M n O y , 2≤a≤8, the Li a M n O y Including Li2M 1 O2、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 Including 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 Including one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, and Li8SnO6.

18. A positive electrode plate, characterized in that: The invention comprises the lithium-rich metal oxide as described in any one of claims 1 to 11.

19. A battery cell, characterized in that: Comprising the positive electrode sheet as described in claim 18.

20. A battery, characterized in that: Comprising the battery cell as claimed in claim 19.

21. An electrical device, characterized in that: Comprising the battery of claim 20.

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