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

Abstract

A lithium-rich metal oxide and a preparation method thereof, a positive electrode sheet, a battery cell and a battery are provided, and belong to the technical field of batteries. The lithium-rich metal oxide comprises a lithium-rich metal oxide core and residual lithium on the surface of the lithium-rich metal oxide core. The content k of the residual lithium satisfies: k≤0.5% based on 100 parts by weight of the lithium-rich metal oxide, and the lithium ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D≥1.0×10 ‑15 cm 2 / s. The lithium-rich metal oxide of the application is applied to the battery cell, and is beneficial to improving the performance of the battery cell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a lithium-rich metal oxide and its preparation method, a positive electrode, a battery cell, and a battery. Background Technology

[0002] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0003] Lithium-rich metal oxides, as materials used in the preparation of positive electrode sheets for 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 urgently needs to be solved. Summary of the Invention

[0004] This 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.

[0005] To achieve the above objectives, this application provides a lithium-rich metal oxide and its preparation method, a positive electrode sheet, a battery cell, and a battery.

[0006] 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 ≤ 0.5 wt%, and the lithium-ion diffusion coefficient D of the lithium-rich metal oxide satisfies: D ≥ 1.0 × 10⁻⁶. - 15 cm 2 / s.

[0007] This application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium-rich metal oxide core has a high lithium-ion content, and using a lithium-rich metal oxide core to prepare the cathode material is beneficial for improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the residual lithium content k on the surface of the lithium-rich metal oxide core is ≤0.5 wt%. This reduces the impact of residual lithium on the processing of the cathode sheet and the effect of residual lithium on the extraction of lithium ions from the lithium-rich metal oxide core, thereby reducing the impact on the charging capacity of the battery cell. The lithium-ion diffusion coefficient D of the lithium-rich metal oxide is ≥1.0 × 10⁻⁶. -15 cm 2 This speed ( / s) facilitates the extraction of lithium ions from the lithium-rich metal oxide, thereby increasing the charging capacity of the battery cell. Therefore, when the lithium-rich metal oxide of this application is used in battery cells, it helps to improve the performance of the battery cell.

[0008] In one possible implementation, k ≤ 0.1 wt%. This further reduces the residual lithium content on the surface of the lithium-rich metal oxide core, which helps to further reduce the impact of residual lithium on the processing of the positive electrode and on the extraction of lithium ions from the lithium-rich metal oxide, thereby facilitating the preparation of the positive electrode and further improving the charging capacity of the battery cell.

[0009] In one possible implementation, D ≥ 1.0 × 10 -12 cm 2 / s. In this way, the diffusion coefficient of lithium ions in lithium-rich metal oxides is further increased, which is conducive to the extraction of lithium ions from lithium-rich metal oxides, thereby helping to further improve the charging capacity of battery cells.

[0010] In one possible implementation, the resistivity p of the lithium-rich metal oxide satisfies: p ≤ 1 Ω·cm; optionally, p ≤ 0.5 Ω·cm. This lower resistivity of the lithium-rich metal oxide is beneficial for improving its conductivity and for the extraction of lithium ions from it, thereby increasing the charging capacity of the battery cell.

[0011] In one possible implementation, the lithium-rich metal oxide further includes: 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 them, z=1; or, X includes SO4. 2- z=2.

[0012] In the above scheme, the lithium-rich metal oxide includes the compound Li on the surface of the lithium-rich metal oxide core. z X. On the one hand, compound Li z X has a relatively small impact on the processing of the positive electrode sheet; for example, the compound Li z X is less likely to cause the binder polyvinylidene fluoride (PVDF) to deform, thus leading to gelation of the cathode slurry. On the other hand, compound Li... z X has a relatively small impact on the extraction of lithium ions from the lithium-rich metal oxide core, which is beneficial for improving the charging capacity of individual battery cells. Therefore, this approach is conducive to improving the performance of individual battery cells.

[0013] In one possible implementation, the lithium-rich metal oxide comprises: the lithium-rich metal oxide core; and a coating layer covering the lithium-rich metal oxide core, the coating layer comprising the compound Li. z X.

[0014] In the above scheme, the coating layer encapsulates the lithium-rich metal oxide core, which helps 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. The coating layer includes the compound Li. z X is beneficial for 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.

[0015] 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 balances the charging capacity of the battery cell with the manufacturing cost of the battery cell.

[0016] In one possible implementation, the compound Li z X is LiF. This is beneficial for further improving the performance of lithium-rich metal oxides, thereby further increasing the charging capacity of individual battery cells.

[0017] In one possible implementation, the median particle size D of the lithium-rich metal oxide is... v 50 has a median particle size of 2μm to 10μm, and can be selected as 4μm to 8μm. When the median particle size of lithium-rich metal oxides is within this range, the path for lithium ions to escape from the lithium-rich metal oxide core is moderate, which is beneficial for lithium ion extraction and improves the charging capacity of battery cells prepared from lithium-rich metal oxides. Furthermore, when the median particle size of lithium-rich metal oxides is within this range, the surface activity of the lithium-rich metal oxides can be controlled, and the aggregation between lithium-rich metal oxide particles or lithium-rich metal oxide core particles can be inhibited, resulting in better particle dispersion, which is beneficial for the compound Li. z The uniform distribution of X on the surface of the lithium-rich metal oxide core. By appropriately setting the median particle size of the lithium-rich metal oxide, the properties of the lithium-rich metal oxide compound Li can be considered. z The uniformity of X distribution and the charging capacity of individual battery cells.

[0018] In one possible implementation, the specific surface area of ​​the lithium-rich metal oxide is 0.2 m². 2 / g~5m 2 / g, optional 0.5m 2 / g~2m 2 / g. This is beneficial for further increasing the capacity of individual battery cells.

[0019] In one possible implementation, the material of the lithium-rich metal oxide core includes Li aM 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 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.

[0020] Secondly, a method for preparing lithium-rich metal oxides 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 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 used in battery cells, it is beneficial to improving the performance of the battery cells.

[0021] In one possible implementation, the treatment includes: sintering in an inert atmosphere for 2 to 10 hours, optionally 4 to 8 hours; and / or, the treatment temperature is 100°C to 600°C, optionally 200°C to 500°C. Thus, by appropriately setting the sintering time and treatment temperature, the reaction between the ammonium salt and the residual lithium on the surface of the lithium-rich metal oxide core is facilitated, so that the compound Li on the surface of the lithium-rich metal oxide core is obtained after the reaction is complete. z X; at the same time, it also helps to save costs and reduce the consumption of active lithium in lithium-rich metal oxide cores.

[0022] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate; alternatively, the ammonium salt includes ammonium fluoride. This allows for flexible selection of the type of ammonium salt based on actual circumstances.

[0023] In one possible implementation, the molar ratio of the ammonium salt to the lithium-rich metal oxide core is 0.021 to 0.15:1, optionally 0.03:1 to 0.08:1. Thus, by appropriately setting the ratio of the ammonium salt to the lithium-rich metal oxide core, the desired compound Li can be generated. z X can also avoid waste caused by excessive ammonium salt content.

[0024] In one possible implementation, the method further includes: subjecting the processed product to airflow crushing and sieving to obtain the lithium-rich metal oxide. This facilitates obtaining lithium-rich metal oxides with suitable particle size.

[0025] 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, 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.

[0026] Thirdly, a positive electrode is provided, comprising the lithium-rich metal oxide of the first aspect and any possible implementation thereof.

[0027] Fourthly, a battery cell is provided, including the positive electrode sheet described in the third aspect.

[0028] Fifthly, a battery is provided, comprising the battery cell described in the fourth aspect.

[0029] In a sixth aspect, an electrical device is provided, comprising the battery described in the fifth aspect.

[0030] This application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium-rich metal oxide core has a high lithium-ion content, and using a lithium-rich metal oxide core to prepare the cathode material is beneficial for improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the residual lithium content k on the surface of the lithium-rich metal oxide core is ≤0.5 wt%. This reduces the impact of residual lithium on the processing of the cathode sheet and the effect of residual lithium on the extraction of lithium ions from the lithium-rich metal oxide core, thereby reducing the impact on the charging capacity of the battery cell. The lithium-ion diffusion coefficient D of the lithium-rich metal oxide is ≥1.0 × 10⁻⁶. -15 cm 2 This speed ( / s) facilitates the extraction of lithium ions from the lithium-rich metal oxide, thereby increasing the charging capacity of the battery cell. Therefore, when the lithium-rich metal oxide of this application is used in battery cells, it helps to improve the performance of the battery cell. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a scanning electron microscope of a lithium-rich metal oxide according to an embodiment of this application;

[0032] Figure 2 A schematic diagram of a scanning electron microscope before the reaction of lithium-rich metal oxide cores;

[0033] Figure 3 This is a schematic diagram of a method for preparing lithium-rich metal oxides according to an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of a battery cell according to an embodiment of this application;

[0035] Figure 5 This is a schematic diagram of a battery module according to an embodiment of this application;

[0036] Figure 6 This is a schematic diagram of a battery according to an embodiment of this application;

[0037] Figure 7This is a schematic diagram of an electrical device according to an embodiment of this application. Detailed Implementation

[0038] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lithium-rich metal oxide, its preparation method, battery cell, battery, and power application 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0039] 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.

[0040] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0041] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0042] 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 method may also 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] 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.

[0044] 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).

[0045] 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 charging capacity.

[0046] Lithium-rich metal oxides (LMEs) have a high lithium-ion content and are widely used in the fabrication of lithium-ion batteries. However, LMEs are relatively unstable and readily react with carbon dioxide and water in the air, forming residual lithium oxides, hydroxides, and carbonates on their surface. The presence of residual lithium affects the performance of LMEs; furthermore, when LMEs are used to fabricate battery cells, the presence of residual lithium is detrimental to cell fabrication and the improvement of cell charging capacity, thus affecting the performance of the battery cells.

[0047] In some processing methods, to improve the performance of lithium-rich metal oxides, an acid is added to the slurry to conduct an acid-base neutralization reaction, thereby reducing the residual lithium content on the surface of the lithium-rich metal oxides. However, the treatment effect of this method is not ideal. On the one hand, the residual lithium content of the lithium-rich metal oxides obtained after treatment is relatively high, and the lithium-ion diffusion coefficient of the lithium-rich metal oxides is relatively low. On the other hand, the uneven distribution of acid in the slurry can easily cause some lithium-rich metal oxides to be over-reacted, leading to a reduction in the active lithium inside the lithium-rich metal oxides, which adversely affects the performance of the battery cells. The lithium-rich metal oxides obtained by the above treatment methods are not conducive to improving the performance of battery cells.

[0048] Therefore, this application provides a lithium-rich metal oxide with a low residual lithium content and a high lithium-ion diffusion coefficient. The lithium-rich metal oxide of this application is beneficial for improving the performance of battery cells.

[0049] [Lithium-rich metal oxides]

[0050] This 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.

[0051] The lithium-rich metal oxide core has a high lithium-ion content, and using a lithium-rich metal oxide core to prepare battery cells is beneficial to improving the charging capacity of the battery cells.

[0052] The material of the lithium-rich metal oxide core is a lithium-rich metal oxide, such as lithium ferrite.

[0053] Optionally, the lithium-rich metal oxide core can be spherical or nearly spherical. This application does not impose specific limitations on the shape of the lithium-rich metal oxide core, as long as the material is a lithium-rich metal oxide.

[0054] 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 or inserted into the lithium-rich metal oxide to participate in the charging and discharging process of the battery cell; the residual lithium on the surface of the lithium-rich metal oxide core does not participate in the charging and discharging process of the battery cell.

[0055] Residual lithium refers to the residual lithium on the surface of lithium-rich metal oxides, also known as free lithium. The surface of the lithium-rich metal oxide core can be the surface of the core closest to the external environment.

[0056] Residual lithium consists of lithium oxides, lithium hydroxides, lithium carbonates, and other products formed by the reaction of lithium-rich metal oxide cores with water, carbon dioxide, and other substances in the air. For example, residual lithium can be in the form of Li₂CO₃, LiOH, or Li₂O.

[0057] Residual lithium is located on the surface of the lithium-rich metal oxide core, affecting the extraction of lithium ions from the core and leading to a decrease in the performance of the lithium-rich metal oxide and a reduction in the charging capacity of the battery cell. Furthermore, the strong alkalinity of residual lithium affects the performance of the binder when the lithium-rich metal oxide core is mixed with a binder to form a slurry for preparing the positive electrode sheet. This can cause denaturation of the binder, such as polyvinylidene fluoride (PVDF), affecting the slurry's performance and coating, thus impacting the positive electrode sheet processing. In the embodiments of this application, based on 100 parts by weight of lithium-rich metal oxide, the residual lithium content k satisfies: k ≤ 0.5 wt%. This reduces the impact of residual lithium on the processing of the positive electrode sheet and minimizes its influence on the extraction of lithium ions from the lithium-rich metal oxide core, thereby reducing the impact on the charging capacity of the battery cell and contributing to an improvement in the charging capacity of the battery cell.

[0058] The lithium-ion diffusion coefficient refers to the average number of lithium ions passing through a unit area of ​​medium per unit time, reflecting the penetration rate of lithium ions in that medium. The lithium-ion diffusion coefficient of lithium-rich metal oxides refers to the diffusion coefficient of lithium ions within the lithium-rich metal oxide.

[0059] The lithium-ion diffusion coefficient D of lithium-rich metal oxides satisfies: D ≥ 1.0 × 10⁻⁶ -15 cm 2 / s. This facilitates the extraction of lithium ions from lithium-rich metal oxides, which helps to increase the charging capacity of individual battery cells.

[0060] 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 lithium-rich metal oxide. 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.

[0061] Optionally, the lithium-rich metal oxides in the embodiments of this application can be used as lithium replenishing agents. For example, the lithium-rich metal oxides can be mixed with other cathode materials to replenish active lithium.

[0062] Alternatively, the lithium-rich metal oxides in the embodiments of this application can also be used as activators. For example, the lithium-rich metal oxides are mixed with a binder and a conductive agent to form a slurry, which is then coated onto the positive current collector to prepare a positive electrode sheet.

[0063] This application provides a lithium-rich metal oxide, comprising a lithium-rich metal oxide core and residual lithium on the surface of the metal oxide core. The lithium-rich metal oxide core has a high lithium-ion content, and using a lithium-rich metal oxide core to prepare the cathode material is beneficial for improving the charging capacity of the battery cell. Based on 100 parts by weight of lithium-rich metal oxide, the residual lithium content k on the surface of the lithium-rich metal oxide core is ≤0.5 wt%. This reduces the impact of residual lithium on the processing of the cathode sheet and the effect of residual lithium on the extraction of lithium ions from the lithium-rich metal oxide core, thereby reducing the impact on the charging capacity of the battery cell. The lithium-ion diffusion coefficient D of the lithium-rich metal oxide is ≥1.0 × 10⁻⁶. -15 cm 2 This speed ( / s) facilitates the extraction of lithium ions from lithium-rich metal oxides, thereby increasing the charging capacity of individual battery cells. Therefore, the lithium-rich metal oxides of this application, when used in battery cells, contribute to improved cell performance.

[0064] In some embodiments, k ≤ 0.1 wt%. This further reduces the residual lithium content on the surface of the lithium-rich metal oxide core, which helps to further reduce the impact of residual lithium on the processing of the positive electrode and on the extraction of lithium ions from the lithium-rich metal oxide, thereby facilitating the preparation of the positive electrode and further improving the charging capacity of the battery cell.

[0065] In some embodiments, D ≥ 1.0 × 10 -12 cm 2 / s. In this way, the diffusion coefficient of lithium ions in lithium-rich metal oxides is further increased, which is conducive to the extraction of lithium ions from lithium-rich metal oxides, thereby helping to further improve the charging capacity of battery cells.

[0066] In some embodiments, the resistivity p of the lithium-rich metal oxide satisfies: p ≤ 1 Ω·cm; optionally, p ≤ 0.5 Ω·cm.

[0067] The lower the resistivity of lithium-rich metal oxides, the higher their conductivity, which is also more conducive to the extraction of lithium ions from the lithium-rich metal oxides.

[0068] In the above embodiments, the resistivity p ≤ 1 Ω·cm of the lithium-rich metal oxide is beneficial to improving the conductivity of the lithium-rich metal oxide and the charging capacity of the battery cell.

[0069] The resistivity p ≤ 0.5 Ω·cm of lithium-rich metal oxides is beneficial for further improving the conductivity of lithium-rich metal oxides and the charging capacity of battery cells.

[0070] Figure 1 This is a schematic diagram of a scanning electron microscope of a lithium-rich metal oxide according to an embodiment of this application. In some embodiments, such as Figure 1 As shown, the lithium-rich metal oxide also includes: the 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 them, z=1; or, X includes SO4. 2- z=2. For example, the compound Li z X can be LiF, LiCl, LiNO3, or Li2SO4.

[0071] Figure 2 This is a schematic diagram of a scanning electron microscope image before the lithium-rich metal oxide core reaction. Figure 2 As shown, the compound Li is formed on the surface of the lithium-rich oxide core. z Prior to X, there was a significant amount of residual lithium on the surface of the lithium-rich metal oxide core.

[0072] compound Li z X can be a product of the reaction between ammonium salt and residual lithium, after which the residual lithium is converted into the compound Li. z X. Compared to residual lithium, compound Li z X will not react with the PVDF adhesive and cause adhesive denaturation; compound Li z X has high electrical conductivity, allowing lithium ions to escape from the compound Li. z X is extracted. Therefore, residual lithium on the surface of the lithium-rich metal oxide core is converted into the compound Li. z X is beneficial for improving the performance of lithium-rich metal oxides, facilitating the preparation of positive electrode sheets, and increasing the charging capacity of battery cells.

[0073] Optionally, combined Figure 1 and Figure 2 As shown, 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.

[0074] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate.

[0075] In the above embodiments, the lithium-rich metal oxide includes the compound Li on the surface of the lithium-rich metal oxide core. z X. On the one hand, compound Li z X has a relatively small impact on the processing of the positive electrode sheet. On the other hand, the compound Li z X has a relatively small impact on the extraction of lithium ions from the lithium-rich metal oxide core, which is beneficial for improving the charging capacity of individual battery cells. Therefore, this approach is conducive to improving the performance of individual battery cells.

[0076] In some embodiments, the lithium-rich metal oxide includes a lithium-rich metal oxide core and a coating layer.

[0077] The coating layer covers a lithium-rich metal oxide core, and the coating layer includes the compound Li z X.

[0078] Prior to the preparation of lithium-rich metal oxides via a lithium-rich metal oxide core and an 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 a portion of the residual lithium is converted into the compound Li. z X. In other words, 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, all the residual lithium is converted into the compound Li. z X; or, after the residual lithium reacts with the ammonium salt, residual lithium remains on the surface of the lithium-rich metal oxide core, meaning that some of the residual lithium is converted into the compound Li. z X, the remaining lithium still exists on the surface of the lithium-rich metal oxide core.

[0079] Optionally, the coating may also include residual lithium.

[0080] Optionally, the coating layer partially coats the lithium-rich metal oxide core. The coating layer is formed at the site of residual lithium before the reaction.

[0081] Optionally, the coating layer covers the entire lithium-rich metal oxide core. This helps to further improve the stability of the lithium-rich metal oxide.

[0082] In the above embodiments, the coating layer covers the lithium-rich metal oxide core, which helps 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. The coating layer includes the compound Li. z X is beneficial for 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.

[0083] In some embodiments, 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.

[0084] In 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 presence of X helps to further improve the ion-conducting properties of lithium-rich metal oxides and the charging capacity of individual battery cells.

[0085] In compound Li z When the molar ratio of X to the lithium-rich metal oxide core is no higher than 0.1:1, the preparation of the compound Li can be controlled. z The demand for X's raw materials helps save costs; at the same time, it also allows control over Li's raw material requirements. z X represents the coating thickness of lithium-rich metal oxides.

[0086] In the above embodiments, compound Li z The molar ratio of X to lithium-rich metal oxide core is 0.01:1 to 0.1:1, which is beneficial to improve the charging capacity of battery cells while taking into account the production and processing costs of battery cells.

[0087] Optionally, 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.

[0088] In some embodiments, compound Li z X is LiF. This is beneficial for further improving the performance of lithium-rich metal oxides, which in turn helps to further increase the charging capacity of individual battery cells.

[0089] In some embodiments, the median particle size D of lithium-rich metal oxides v 50 is 2μm~10μm, and can be selected from 4μm~8μm.

[0090] Median particle size D v 50 can refer to the particle size corresponding to a sample when the cumulative volume distribution percentage reaches 50%.

[0091] 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, the smaller the median particle size of the lithium-rich metal oxide core, and the larger the median particle size D of the lithium-rich metal oxide core. v The smaller the value of 50.

[0092] If the median particle size of lithium-rich metal oxides 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 lithium ion extraction and affects the charging capacity of battery cells prepared from lithium-rich metal oxides. If the median particle size of lithium-rich metal oxides is too small, the surface activity of lithium-rich metal oxides is too high, 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 the uniform formation of Li compound on the surface of lithium-rich metal oxide cores. z X.

[0093] In the above embodiments, the median particle size D of the lithium-rich metal oxide v The lithium oxide (Li₂O₅) core has a particle size of 2μm to 10μm, providing a suitable pathway for lithium ion extraction, which is beneficial for lithium ion extraction and improving the charging capacity of battery cells prepared from lithium oxide-rich metal oxides. Furthermore, it helps control the surface activity of lithium oxide-rich metal oxides, inhibiting agglomeration between lithium oxide particles or core particles, resulting in good particle dispersion, which is beneficial for the compound Li. z The uniform distribution of X on the surface of the lithium-rich metal oxide core. By appropriately setting the median particle size of the lithium-rich metal oxide, the properties of the lithium-rich metal oxide compound Li can be considered. z The uniformity of the X distribution and the charging capacity of individual battery cells.

[0094] In some embodiments, the specific surface area of ​​the lithium-rich metal oxide is 0.2 m². 2 / g~5m 2 / g, optional 0.5m 2 / g~2m 2 / g. This is beneficial for further increasing the capacity of individual battery cells.

[0095] 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 m². 2 / g~2m 2 / g. This helps to increase the charging capacity of individual battery cells.

[0096] In some embodiments, the material of the lithium-rich metal oxide core 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, 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 5Including 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.

[0097] The embodiments of the lithium-rich metal oxides of this application have been described above. The embodiments of the preparation methods of the lithium-rich metal oxides will be described in detail below. For any parts not described in the embodiments of the preparation methods of the lithium-rich metal oxides, please refer to the relevant descriptions of the embodiments of the lithium-rich metal oxides.

[0098] [Preparation methods of lithium-rich metal oxides]

[0099] Figure 3 This is a schematic diagram of a method for preparing lithium-rich metal oxides according to an embodiment of this application. Figure 3 As shown, method 100 includes steps 110 and 120.

[0100] Step 110, providing an ammonium salt and a lithium-rich metal oxide core.

[0101] Step 120: Mix the ammonium salt and the lithium-rich metal oxide core and process them to obtain the lithium-rich metal oxide.

[0102] Because lithium-rich metal oxide cores readily react with water and carbon dioxide in the air, residual lithium, such as Li₂CO₃, LiOH, and Li₂O, remains on the surface of these cores. Ammonium salts can react with this residual lithium, and after the reaction, at least some of the residual lithium is converted into the compound Li. z X.

[0103] After the ammonium salt reacts with the residual lithium on the surface of the lithium-rich metal oxide core, the content of residual lithium on the surface of the lithium-rich metal oxide core decreases. For example, it can be reduced to less than 0.5 wt% or even 0.1 wt% of the weight of the lithium-rich metal oxide.

[0104] Compared to residual lithium, compound Li z X exhibits superior electrical conductivity, has minimal impact on lithium-ion extraction from lithium-rich metal oxides, and also has minimal impact on the PVDF adhesive. Furthermore, at least a portion of the surface of the lithium-rich metal oxide is composed of the compound Li. z X or compound Li z X and residual lithium are also less likely to react with water and carbon dioxide in the air.

[0105] In the embodiments of this application, the lithium-rich metal oxide prepared by method 100 has high conductivity and stability. When the lithium-rich metal oxide of this application is applied to battery cells, it is beneficial to improve the performance of battery cells.

[0106] In some embodiments, the process includes: sintering in an inert atmosphere for 2 h to 10 h, optionally 4 h to 8 h; and / or, the processing temperature is 100 °C to 600 °C, optionally 200 °C to 500 °C.

[0107] Optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium. This allows for the selection of a suitable inert gas based on actual needs.

[0108] When the sintering time in an inert atmosphere is not less than 2 hours, it is beneficial for 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 and helps to reduce costs.

[0109] At a processing temperature of not less than 100℃, it is beneficial for ammonium salt to fully react with residual lithium on the surface of lithium-rich metal oxide core; at a processing temperature of not more than 600℃, it is beneficial for maintaining the content of active lithium in lithium-rich metal oxide core.

[0110] Optionally, sintering in an inert atmosphere for 4 to 8 hours can further balance the reaction between ammonium salt and residual lithium and production costs.

[0111] Optionally, the processing temperature is 200℃~500℃, which can further balance the reaction between ammonium salt and residual lithium and the content of active lithium in the lithium-rich metal oxide core.

[0112] In the above embodiments, by reasonably setting the sintering time and processing temperature, the reaction between the ammonium salt and the lithium-rich metal oxide core is facilitated, so that the compound Li on the surface of the lithium-rich metal oxide core is obtained after the reaction is completed. z X; at the same time, it also helps to save costs and reduce the consumption of active lithium in lithium-rich metal oxide cores.

[0113] Optionally, the ammonium salt includes at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate; alternatively, the ammonium salt includes ammonium fluoride. This allows for flexible selection of the type of ammonium salt based on actual circumstances.

[0114] In some embodiments, the molar ratio of ammonium salt to lithium-rich metal oxide core is 0.021 to 0.15:1, optionally 0.03:1 to 0.08:1. Thus, by rationally setting the ratio of ammonium salt to lithium-rich metal oxide core, the desired compound LizX can be generated while avoiding waste caused by excessive ammonium salt content.

[0115] In some embodiments, method 100 further includes: subjecting the processed product to airflow crushing and sieving to obtain lithium-rich metal oxides. This facilitates obtaining lithium-rich metal oxides with suitable particle size.

[0116] In some embodiments, the material of the lithium-rich metal oxide core 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, 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.

[0117] In some embodiments, the temperature of the above-described treatment does not exceed 500°C, and optionally, the temperature does not exceed 300°C. This allows for the realization of a lithium-rich metal oxide 1 with a uniform and dense coating layer at a lower temperature.

[0118] In some embodiments, a lithium-rich metal oxide core is provided, comprising: combining a Li source with M n The sources are mixed uniformly at a molar ratio of (a+0.05):1 to a:1 and then sintered once in an inert atmosphere for 4 to 8 hours at a sintering temperature of 400℃ to 600℃; wherein the Li source includes one or more of lithium oxide, lithium carbonate, lithium oxalate, lithium acetate, and lithium hydroxide, M n Sources include Mn The lithium-rich metal oxide core is prepared by sintering one or more of the following: oxides, hydroxides, halides, sulfates, carbonates, nitrates, oxalates, acetates, sulfides, and nitrides. Optionally, the sintering temperature is 450℃~550℃. Optionally, the inert atmosphere includes one or more of nitrogen, argon, and helium. The product from the first sintering is subjected to airflow crushing to obtain a lithium-rich metal oxide core. This facilitates the preparation of suitable lithium-rich metal oxide cores for subsequent lithium-rich metal oxide preparation. Furthermore, this method prepares lithium-rich metal oxide cores at a lower sintering temperature, which helps reduce costs and also helps reduce the volatilization of active lithium.

[0119] [Positive electrode plate]

[0120] This application provides a positive electrode, including lithium-rich metal oxide in any of the embodiments.

[0121] [Battery cell]

[0122] This application provides a battery cell including the positive electrode sheet in the above embodiments.

[0123] 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.

[0124] Figure 4 This is a schematic diagram of a battery cell according to an embodiment of this application. Figure 4 As shown, the battery cell 4 includes a housing 31, a cover plate 32, and an electrode assembly 33 disposed in the housing 31.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Figure 5 This is a schematic diagram of a battery module according to an embodiment of this application. (Refer to...) Figure 5 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.

[0129] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 3 are received.

[0130] [Battery]

[0131] This application provides a battery, including the battery cell described in the above embodiments.

[0132] Figure 6 This is a schematic diagram of a battery according to an embodiment of this application. Figure 6 As shown, this application provides a battery 5, including the battery cell 3 in any of the above embodiments.

[0133] 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.

[0134] [Electrical appliances]

[0135] This application provides an electrical device, including the battery described in the above embodiments.

[0136] Figure 7 This is a schematic diagram of an electrical device according to an embodiment of this application. Figure 7 As shown, this application provides an electrical device 6, which includes the battery 5 in the above embodiment.

[0137] 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.

[0138] [Example]

[0139] Example 1

[0140] In Example 1, a lithium-rich metal oxide core was reacted with an ammonium salt at 350°C for 6 hours to obtain a lithium-rich metal oxide. The lithium-rich metal oxide core was Li5FeO4, and the molar ratio m1 of the ammonium salt NH4F to the lithium-rich metal oxide core Li5FeO4 was 0.05:1.

[0141] Li compounds on the surface of lithium-rich metal oxide cores z X is LiF, the molar ratio m2 of compound LiF to the lithium-rich metal oxide core Li5FeO4 is 0.03:1, the residual lithium content k on the surface of the lithium-rich metal oxide core is 0.021 wt%, and the lithium ion diffusion coefficient D of the lithium-rich metal oxide is 2.8 × 10⁻⁶. -11 cm 2The resistivity p of the lithium-rich metal oxide is 0.22 Ω·cm, and the specific surface area s is 1.215 m² / s. 2 / g.

[0142] Examples 2-5

[0143] The difference between Examples 2-5 and Example 1 is that the molar ratio m1 of ammonium salt NH4F and lithium-rich metal oxide core Li5FeO4 is different.

[0144] 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 compound LiF to the lithium-rich metal oxide core Li5FeO4 also change. Specific parameters can be found in Table 1.

[0145] Examples 6-9

[0146] The difference between Examples 6-9 and Example 1 is that the reaction temperature T1 of ammonium salt NH4F and lithium-rich metal oxide core Li5FeO4 is different.

[0147] 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 compound LiF to the lithium-rich metal oxide core Li5FeO4 also change. Specific parameters can be found in Table 1.

[0148] Examples 10-13

[0149] The difference between Examples 10-13 and Example 1 is that the reaction time L between ammonium salt NH4F and lithium-rich metal oxide core Li5FeO4 is different.

[0150] 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 compound LiF to the lithium-rich metal oxide core Li5FeO4 also change. Specific parameters can be found in Table 1.

[0151] Examples 14-17

[0152] The difference between Examples 14-17 and Example 1 is that the median particle size D of the lithium-rich metal oxides is... v 50 are different.

[0153] 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. Specific parameters can be found in Table 1.

[0154] Examples 18-21

[0155] The difference between Examples 18-21 and Example 1 is that the ammonium salts are different.

[0156] Correspondingly, the diffusion coefficient D of lithium ions in lithium-rich metal oxides also changes. Specific parameters can be found in Table 1.

[0157] Example 22

[0158] The difference between Example 22 and Example 1 is that the molar ratio m1 of ammonium salt NH4F and lithium-rich metal oxide core Li5FeO4 and the reaction temperature T1 are different.

[0159] Example 23

[0160] The difference between Example 23 and Example 1 is that the molar ratio m1 of ammonium salt NH4F to lithium-rich metal oxide core Li5FeO4, the reaction temperature T1, and the reaction time L are different.

[0161] Example 24

[0162] The difference between Example 24 and Example 1 lies in the molar ratio m1 of ammonium salt NH4F to lithium-rich metal oxide core Li5FeO4, the reaction time L, and the median particle size D of the lithium-rich metal oxide. v 50 are different.

[0163] Example 25

[0164] The difference between Example 25 and Example 1 is: the reaction temperature T1 of ammonium salt NH4F with the lithium-rich metal oxide core Li5FeO4, and the median particle size D of the lithium-rich metal oxide. v 50 are different.

[0165] Examples 26-29

[0166] The difference between Examples 26-29 and Example 1 lies in the material of the lithium-rich metal oxide core. Specifically, the materials of the lithium-rich metal oxide core are Li6CoO4, Li2CuO2, Li2NiO2, and Li3NbO4, respectively.

[0167] Comparative Example 1

[0168] The difference between Comparative Example 1 and Example 1 is that the lithium-rich metal oxide core Li5FeO4 was not used to react with ammonium salt to prepare lithium-rich metal oxide, and the lithium-rich metal oxide core Li5FeO4 was used as the lithium-rich metal oxide.

[0169] Comparative Examples 2-5

[0170] The difference between Comparative Examples 2-5 and Comparative Example 1 is that the lithium-rich metal oxide cores are different.

[0171] [Preparation methods of lithium-rich metal oxides]

[0172] After the lithium-rich metal oxide core and ammonium salt are mixed evenly, they are sintered in an inert atmosphere. After sintering, the mixture is subjected to airflow crushing and sieving to obtain the lithium-rich metal oxide.

[0173] [Testing for residual lithium content]

[0174] The residual lithium content in lithium-rich metal oxides was measured by titrating them with a standard hydrochloric acid solution.

[0175] The residual lithium on the surface of lithium-rich metal oxides, including lithium carbonate and lithium hydroxide, is used as an example for illustration. m1g of lithium-rich metal oxide is added to b mL of deionized water and stirred at 200 rpm for 5 min. The lithium-rich metal oxide is then titrated with a standard hydrochloric acid solution (hydrochloric acid concentration cmol / L) (the hydrochloric acid reacts with the lithium carbonate and lithium hydroxide in the lithium-rich metal oxide). A composite pH electrode is used as the indicator electrode, and the titration endpoint is determined by the abrupt change in potential. The residual lithium content of the lithium-rich metal oxide is then calculated.

[0176] In the titration reaction, potential jump points E1 and E2 occur. 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 point is V1. At potential jump point E2, lithium bicarbonate reacts with hydrochloric acid to form lithium chloride. The volume of hydrochloric acid consumed at this point is V2. Based on the volumes of hydrochloric acid consumed, V1 and V2, the residual lithium content can be calculated.

[0177] [Compound Li] z [X's Test]

[0178] A mg sample of lithium-rich metal oxide was taken to test the residual lithium content. Based on the mass of the lithium-rich metal oxide, the mass fraction of residual lithium was determined to be h%, and the molar number of lithium ions in the residual lithium was then calculated as (h×m) / M. Li (M) Li (where is the relative atomic mass of lithium).

[0179] mg of lithium-rich metal oxide was analyzed by inductively coupled plasma atomic emission spectrometry (ICP) to obtain a total lithium-ion mass fraction of k%, with M% of metal. n The mass fraction is t%, thus the total number of lithium ion moles is (k×m) / M. Li Metal M n The number of moles is (t×m) / M n (M) n For metallic element M n (relative atomic mass).

[0180] LizX and lithium-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.

[0181] Inductively coupled plasma atomic emission spectrometry (ICP) testing can be performed using an ICP-AES spectrometer (such as the ICAP7400 from Thermo Fisher Scientific, USA). An exemplary testing method is as follows: 2g of the metal oxide material is added to an acid solution (such as aqua regia) for digestion. Digestion can be carried out under stirring (e.g., mechanical stirring or microwave stirring) for 30 minutes. The digested solution is then added to the ICAP7400 spectrometer for quantitative analysis of the chemical elemental composition of the metal oxide material.

[0182] [Specific surface area test]

[0183] The specific surface area (BET) of positive electrode active materials is a well-known concept in the art and can be tested using instruments and methods known in the art. For example, the specific surface area can be tested using the gas adsorption method according to the GB / T19587-2017 testing standard. Specifically, a lithium-rich metal oxide material is taken as a sample, and the sample tube is immersed in liquid nitrogen at -196℃. The amount of nitrogen adsorbed on the solid surface at different pressures of 0.05-0.30 is measured. Based on the BET multilayer adsorption theory and its formula, the monolayer adsorption amount of the sample is obtained, thereby calculating the specific surface area of ​​the lithium-rich metal oxide material.

[0184] Median particle size D of lithium-rich metal oxides v [Test of 50]

[0185] In lithium-rich metal oxides, the median particle size D v 50 can be determined using a laser particle size analyzer, referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0186] [Resistivity Testing of Lithium-Rich Metal Oxides]

[0187] 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.

[0188] [Lithium-ion diffusion coefficient test]

[0189] 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.

[0190] 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:

[0191] ( ) in, V is the lithium-ion diffusion coefficient; I0 ​​is the applied current of 20 μA; V m denoted as , where 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) / (dt1 / 2) is the slope of the polarization voltage versus t1 / 2 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.

[0192] [Preparation of Lithium-ion Batteries]

[0193] Preparation of the positive electrode sheet: Lithium-rich metal oxide, polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent were dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 97:2:1. After thorough mixing, a positive electrode slurry was prepared. The positive electrode slurry was 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 was used as the active material, and no other active materials were added.

[0194] 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.

[0195] Separating membrane: made of polypropylene membrane.

[0196] Preparation of electrolyte: Ethyl carbonate (EC), methyl ethyl 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 the electrolyte was 1 mol / L.

[0197] 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.

[0198] [Testing the first charge capacity of lithium-ion batteries]

[0199] 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.

[0200] Table 1. Specific parameters and experimental results of the examples and comparative examples.

[0201]

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

[0203] As shown in Examples 1-25 and Comparative Example 1, the residual lithium content in Comparative Example 1 is relatively high, and the charging capacity of the lithium-ion battery in Comparative Example 1 is significantly lower than that of the lithium-ion batteries in Examples 1-25 of this application. Similarly, as shown in Examples 26-29 and Comparative Examples 2-5, the residual lithium content in Comparative Examples 2-5 is relatively high, and the charging capacity of the lithium-ion batteries in Comparative Examples 2-5 is significantly lower than that of the lithium-ion batteries in Examples 26-29 of this application. As shown in Examples 1-5 and Examples 22-24, appropriately setting the molar ratio of ammonium salt to lithium-rich metal oxide core is beneficial for obtaining a more suitable lithium-containing compound, Li. z The molar ratio of X to the lithium-rich metal oxide core reduces the residual lithium content on the surface of the lithium-rich metal oxide core, increases the lithium-ion diffusion coefficient, reduces the resistivity of the lithium-rich metal oxide, and improves the charging capacity of the lithium-ion battery cell. Combined with Examples 6-9, 10-13, and 23-24, appropriately setting the reaction temperature and reaction time between the ammonium salt and the lithium-rich metal oxide core is beneficial for obtaining a more suitable lithium-containing compound, Li. zThe molar ratio of X to the lithium-rich metal oxide core is beneficial for reducing the residual lithium content on the surface of the lithium-rich metal oxide core, increasing the lithium-ion diffusion coefficient, reducing the resistivity of the lithium-rich metal oxide, and improving the charging capacity of the lithium-ion battery cell. As shown in Examples 14-17 and 24-25, appropriately setting the median particle size of the lithium-rich metal oxide is beneficial for obtaining a suitable specific surface area, reducing the residual lithium content on the surface of the lithium-rich metal oxide core, increasing the lithium-ion diffusion coefficient, and improving the charging capacity of the lithium-ion battery cell. As shown in 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 for improving the charging capacity of the lithium-ion battery. As shown in Examples 26-29, a variety of different materials can be selected for the lithium-rich metal oxide core.

[0204] 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, Comprising: a lithium-rich metal oxide inner core; residual lithium on the surface of the lithium-rich metal oxide inner core; wherein 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, based on 100 parts by weight of the lithium-rich metal oxide.

2. The lithium-rich metal oxide of claim 1, wherein k≤0.1wt%.

3. The lithium-rich metal oxide of claim 1, wherein D ≥ 1.0 x 10 -12 cm 2 / s.

4. The lithium-rich metal oxide of claim 1, wherein The resistivity p of the lithium-rich metal oxide satisfies: p≤1Ω·cm.

5. The lithium-rich metal oxide of claim 4, wherein p≤0.5Ω·cm.

6. The lithium-rich metal oxide of claim 1, wherein The lithium-rich metal oxide further includes: a compound Li z X, wherein X includes at least one of F - , Cl - , NO3 - , and HSO4 -1 , z = 1; or, X comprises SO4 2- z = 2.

7. The lithium-rich metal oxide of claim 6, wherein The lithium-rich metal oxide comprises: a lithium-rich metal oxide inner core; a cladding layer cladding the lithium-rich metal oxide inner core, the cladding layer comprising the compound Li z X.

8. The lithium-rich metal oxide of claim 6, wherein The compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.01:1 to 0.1:

1.

9. The lithium-rich metal oxide of claim 8, wherein, The compound Li z The molar ratio of X to the lithium-rich metal oxide core is 0.02:1 to 0.05:

1.

10. The lithium-rich metal oxide of claim 6, wherein The compound Li z X is LiF.

11. The lithium-rich metal oxide of any one of claims 1-10, wherein, The median particle size D of the lithium-rich metal oxide is in the range of 2 μm to 10 μm. v 50 is 2 μm to 10 μm.

12. The lithium-rich metal oxide of claim 11, wherein The median particle size D of the lithium-rich metal oxide is in the range of 1 μm to 10 μm, preferably in the range of 2 μm to 8 μm, more preferably in the range of 3 μm to 6 μm. v 50 is 13. The lithium-rich metal oxide of any one of claims 1-10, wherein, The specific surface area of the lithium-rich metal oxide is 0.2 m 2 / g~5m 2 / g.

14. The lithium-rich metal oxide of claim 13, wherein, The specific surface area of the lithium-rich metal oxide is 0.5 m 2 / g~2m 2 / g.

15. The lithium-rich metal oxide of any one of claims 1-10, 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.

16. The lithium-rich metal oxide of claim 15, wherein, The Li a M n O y one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, Li8SnO6.

17. A method of preparing a lithium-rich metal oxide, characterized by, The method comprises: providing an ammonium salt and a lithium-rich metal oxide inner core; mixing the ammonium salt and the lithium-rich metal oxide inner core, and performing a treatment to obtain the lithium-rich metal oxide.

18. The method of claim 17, wherein, The treatment comprises: sintering for 2h~10h in an inert atmosphere; and / or, The temperature of the treatment is 100℃~600℃.

19. The method of claim 18, wherein, sintering for 4h~8h in an inert atmosphere.

20. The method of claim 18, wherein, The temperature of the treatment is 200℃~500℃.

21. The method of claim 17, wherein, The ammonium salt comprises at least one of ammonium fluoride, ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium bisulfate.

22. The method of claim 21, wherein, The ammonium salt comprises ammonium fluoride.

23. The method of any one of claims 17-22, wherein, The molar ratio of the ammonium salt to the lithium-rich metal oxide inner core is 0.02~0.15:

1.

24. The method of claim 23, wherein, The molar ratio of the ammonium salt to the lithium-rich metal oxide inner core is 0.03:1~0.08:

1.

25. The method of any one of claims 17-22, wherein, The method further comprises: performing airflow crushing and sieving on the product after the treatment to obtain the lithium-rich metal oxide.

26. The method of any one of claims 17-22, 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.

27. The method of claim 26, wherein, The Li a M n O y one or more of Li2NiO2, Li2CuO2, Li2MnO3, Li3VO4, Li3NbO4, Li5FeO4, Li6CoO4, Li8SnO6.

28. A positive electrode sheet characterized by comprising: The lithium-rich metal oxide comprises:

29. A battery cell, characterized by The positive electrode sheet comprises:

30. A battery, comprising: The battery cell comprises:

31. An electrical device, comprising: The battery comprises:

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