Positive electrode active material, method for producing same, battery cell, and electric device

Abstract

This application discloses a positive electrode active material and its preparation method, a battery cell, and an electrical device. The positive electrode active material includes the compound Li. a (Ni b Mn c M d )Q δ O 4‑δ / 2 Wherein, 0.9≤a≤1.1, b>0, c>0, d>0, b+c+d=2, 0≤δ≤0.5, M includes at least three of Fe, Cr, Cu, Nb, Ti, Al, Mg, Zr, Sb, and Ga, and Q includes at least one of F and Cl. The positive electrode active material has a crystal structure that can be classified into space group Fd-3m, and the cations of the transition metal sites in the crystal structure of space group Fd-3m are at least partially disordered. The positive electrode active material of this application maintains a single-phase structure and uniform elemental distribution under high doping levels, while suppressing the irreversible transformation of spinel to rock salt phase under high voltage and high rate cycling conditions, and reconstructing the two-phase reaction into a milder solid solution reaction. Thus, the battery has good electrochemical performance.

Description

Technical Field

[0001] This application belongs to the field of lithium battery technology, and particularly relates to a positive electrode active material and its preparation method, a battery cell, and an electrical device. Background Technology

[0002] High-voltage spinel-type lithium nickel manganese oxide (LNMO) cathode material, by introducing nickel to participate in high-potential redox reactions, achieves a significant increase in energy density compared to traditional lithium manganese oxide materials, becoming a core candidate system for next-generation high-energy-density lithium-ion battery cathode materials, and possessing extremely high industrial application value.

[0003] However, existing LNMO cathode materials are still constrained by many technical bottlenecks, limiting their large-scale promotion. Specifically, under high voltage and high rate cycling, repeated lithium-ion insertion and extraction can induce the migration of nickel and manganese transition metal ions, causing irreversible phase transitions from spinel to rock salt phase and generating phase boundary stress and microcracks in particles. This leads to loss of active phase and rapid capacity decay. During charge and discharge, the two-phase reaction can cause particle cracking and electrode structure collapse due to lattice mismatch and interfacial energy accumulation, affecting structural integrity and reducing long-cycle stability. At the same time, its high operating voltage of 4.9 V can cause oxidation and decomposition of conventional electrolytes, forming an unstable interfacial layer on the particle surface, further aggravating the dissolution of transition metals and increasing interfacial impedance, significantly shortening the battery cycle life. This has become the core problem hindering the practical application of this material. Summary of the Invention

[0004] This application provides a positive electrode active material, its preparation method, a battery cell, and an electrical device. The positive electrode active material maintains a single-phase structure and uniform elemental distribution even with high doping levels. Simultaneously, it suppresses the irreversible transformation of spinel to rock salt phase under high voltage and high rate cycling conditions, and reconstructs the two-phase reaction into a milder solid solution reaction. This results in batteries using this positive electrode active material exhibiting excellent electrochemical performance.

[0005] In a first aspect, embodiments of this application provide a positive electrode active material, including the compound Li a (Ni b Mn c M d )Q δ O 4-δ / 2 Wherein, 0.9≤a≤1.1, b>0, c>0, d>0, b+c+d=2, 0≤δ≤0.5, M includes at least three of Fe, Cr, Cu, Nb, Ti, Al, Mg, Zr, Sb and Ga, and Q includes at least one of F and Cl. The positive electrode active material has a crystal structure that can be classified into space group Fd-3m, and the cations of the transition metal sites in the crystal structure of space group Fd-3m are at least partially disordered.

[0006] According to the embodiments of this application, the positive electrode active material of this application adopts multi-element synergistic doping and anion site regulation modification. Relying on the crystal structure of space group Fd-3m, it achieves that the material still maintains a single-phase structure and the constituent elements are uniformly distributed even with high doping levels, solving the phase separation and element segregation problems that are prone to occur in traditional high-doped materials. At the same time, by regulating the structural control of the disordered distribution of the cation part of the transition metal site, under high voltage and high rate cycling conditions, it can effectively suppress the irreversible structural transformation of spinel phase to rock salt phase, block the generation pathway of phase boundary stress and particle microcracks, and transform the traditional L The intense two-phase reaction of NMO material is reconstructed into a solid solution reaction with milder kinetics and smaller lattice strain, eliminating particle cracking and electrode structure collapse caused by lattice mismatch and interfacial energy accumulation. In addition, the special crystal structure and elemental composition of this material can optimize the stability of the electrode interface, alleviate the side reaction of electrolyte oxidation decomposition at high potentials, reduce the dissolution of transition metal ions, and reduce the rate of interfacial impedance growth. Based on the dual optimization of the above structure and reaction mechanism, the secondary battery cell equipped with this positive electrode active material ultimately has high energy density, excellent rate charge and discharge performance, and cycle life.

[0007] In some alternative embodiments, the positive electrode active material satisfies at least one of the following: (1) 0.3≤b≤0.5. A nickel element ratio of 0.3≤b≤0.5 can maintain the material's high voltage plateau and high energy density advantage of 4.7V~4.9V, while avoiding excessive nickel content from aggravating transition metal migration and structural distortion. (2) 1.3≤c≤1.5. A manganese element ratio of 1.3≤c≤1.5 fits the ideal lattice coordination requirements of spinel-type materials, retaining the core advantages of low cost and high safety of manganese-based materials, while also suppressing Jahn-Teller instability and Mn dissolution with the help of doping elements. (3) 0.03≤d≤0.4. The doping element ratio of 0.03≤d≤0.4 can ensure that the multivalent doping elements can fully play their role in lattice stability and charge compensation, and will not result in insufficient modification effect due to excessive doping amount, or excessive doping will affect the main spinel skeleton of the material. Combined with the structural characteristics of the disordered distribution of cations at transition metal sites, it can effectively block the irreversible transformation of spinel phase to rock salt phase under high voltage and high rate cycling conditions.

[0008] In some alternative embodiments, M includes Fe, Cr, Cu and Nb, and the molar ratio of Fe, Cr, Cu and Nb is 1:(0.9~1.1):(0.9~1.1):(0.9~1.1).

[0009] In the above-mentioned optional embodiments, the molar ratios of Fe, Cr, Cu, and Nb are nearly equal, which can achieve uniform occupancy of lattice sites and charge balance, avoiding lattice distortion and local stress concentration problems caused by excessive doping of a single element. At the same time, Fe can regulate the valence state of transition metals and suppress the Jahn-Teller effect, Cr can enhance the stability of the lattice framework and block irreversible phase transitions, Cu can optimize lithium-ion diffusion kinetics and improve rate performance, and Nb can passivate active sites on the material surface and alleviate interfacial side reactions. The four elements work together to exert the modification effects of lattice stability, charge compensation, and kinetic optimization in an all-round way. The modification effect will not be insufficient due to too low doping amount, nor will the spinel crystal framework of the material be affected by the imbalance of doping ratio.

[0010] In some alternative implementations, the configurational entropy S of the transition metal site conf Satisfy: 0.6R≤S conf ≤1.3R, where R is the gas constant.

[0011] In the above optional embodiments, the configurational entropy S of the transition metal site conf Satisfy: 0.6R≤S conf At ≤1.3R, the stability of the disordered distribution of transition metal cations can be enhanced through entropy stabilization effect, ensuring that the material is in a high-entropy or near-high-entropy state. This is beneficial for stabilizing a single solid solution phase, offsetting the driving force of ion migration under high-voltage cycling, and suppressing the irreversible transformation from spinel phase to rock salt phase. It can also reduce the risk of element segregation and phase separation caused by excessively low configuration entropy, as well as the problems of excessive lattice disorder and main structure collapse caused by excessively high configuration entropy, thus precisely balancing lattice stability and ion transport efficiency. Combined with the configuration entropy regulation effect, the violent two-phase reaction of traditional LNMO can be further reconstructed into a solid solution reaction with mild kinetics and minimal lattice strain, eliminating the problems of particle cracking and structural collapse caused by lattice mismatch and interfacial energy accumulation.

[0012] In some alternative implementations, 0.8R ≤ S conf ≤1.0R.

[0013] In the above optional embodiments, the configurational entropy S of the transition metal site conf Satisfying: 0.8R≤S conf At ≤1.0R, it can further balance the stability of the crystal structure, ion transport kinetics and charge transport efficiency; combined with the entropy regulation effect of this superior configuration, it can further reconstruct the violent two-phase reaction during the charging and discharging process of traditional LNMO materials into a solid solution reaction with milder kinetics and negligible lattice strain, and completely eliminate the problems of lattice mismatch and interface energy accumulation caused by multi-step phase transition.

[0014] In some optional embodiments, the positive electrode active material satisfies at least one of the following: (1) the average particle size of the positive electrode active material is 0.5 μm to 20 μm; (2) the working platform voltage of the positive electrode active material is 4.6 V to 4.8 V.

[0015] Secondly, embodiments of this application provide a method for preparing a positive electrode active material, comprising: Li, Ni, Mn, M, and Q sources were mixed in a predetermined ratio and then ground to obtain a precursor slurry. The molar ratio of Ni to M in the precursor slurry was 0.7–17, and the molar ratio of Mn to M was 3–50. The precursor slurry was dried to obtain a precursor powder. The precursor powder was then subjected to tableting, sintering, and pulverizing processes to obtain the positive electrode active material of the first aspect.

[0016] According to the embodiments of this application, the preparation method eliminates the complex post-coating processing steps required for conventional modified LNMO materials, saving multiple additional steps such as coating agent preparation, coating treatment, and secondary heat treatment, significantly shortening the overall preparation cycle. The process flow is extremely simple, and the ease of operation is greatly improved. It can also effectively ensure the uniformity of elemental distribution, crystal structure consistency, and electrochemical performance stability of different batches of products, avoiding performance fluctuations between batches, and effectively reducing production energy consumption and raw material loss, controlling the cost of large-scale production. The overall process has strong compatibility, low scale-up difficulty, and no complex process bottlenecks, showing excellent prospects for pilot-scale amplification and continuous industrial production.

[0017] In some optional embodiments, the preparation method satisfies at least one of the following: (1) the grinding treatment is wet ball milling, and the ball milling speed is 200 r / min to 400 r / min. (2) the grinding treatment time is 8 h to 24 h. (3) the ratio of the sum of the masses of Li source, Ni source, Mn source, M source and Q source to the mass of the grinding media in the grinding treatment is 1:(5 to 20). (4) the drying treatment temperature is 60℃ to 120℃. (5) the drying treatment time is 8 h to 24 h. (6) the tableting treatment pressure is 2 MPa to 20 MPa. (7) the tableting treatment holding time is 1 min to 3 min. (8) the sintering treatment heating rate is 3℃ / min to 10℃ / min. (9) the sintering treatment sintering temperature is 750℃ to 900℃. (10) the sintering treatment holding time is 12 h to 24 h.

[0018] Thirdly, embodiments of this application provide a secondary battery cell, including the positive electrode active material of the first aspect and / or the positive electrode active material prepared by the preparation method of the second aspect.

[0019] Fourthly, embodiments of this application provide an electrical device including a secondary battery cell as described in the third aspect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The diagram shown is a schematic diagram of a battery cell provided in some embodiments of this application.

[0022] Figure 2 The diagram shown is a schematic diagram of an electrical device provided in some embodiments of this application.

[0023] Figure 3 The image shows the XRD pattern and Rietveld refinement results of HELNMO, a positive electrode active material according to an embodiment of this application.

[0024] Figure 4 The image shown is the Raman spectrum of HELNMO, a positive electrode active material according to an embodiment of this application.

[0025] Figure 5 The image shown is an atomically resolved HAADF-STEM image of LNMO and HELNMO, the positive electrode active material of some embodiments of this application, after 1000 cycles in 2C, and a schematic diagram of the surface structure evolution.

[0026] Figure 6 The figure shows the leaching statistics of Mn / Ni from LNMO and HELNMO deposited on the negative electrode after 200 cycles of 2C, using LNMO and HELNMO, the positive electrode active materials of some embodiments of this application.

[0027] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0028] The following detailed description, with appropriate reference to the accompanying drawings, discloses the solid-state metal battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0029] 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 5-100 and 10-20 are listed for a specific parameter, it is expected that ranges of 5-20 and 10-100 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, 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" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations.

[0030] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0031] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0032] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means 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.

[0033] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0034] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0035] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0037] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0038] The secondary battery cells mentioned in the embodiments of this application can independently perform charge and discharge functions. The battery cells in the embodiments of this application can be liquid battery cells, i.e., lithium-ion battery cells, or solid-state battery cells. The battery cells can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0039] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0040] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0041] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0042] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0043] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0044] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0045] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0046] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0047] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0048] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Solid-state metal battery cells and battery devices are used to store or provide electrical energy.

[0049] Figure 2 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0050] The battery cells in this application may include button cells, molded cells, hard-case cells, soft-pack cells, etc.

[0051] Lithium-ion batteries, with their core advantages such as high energy density, long cycle life, low self-discharge rate, and no memory effect, have been widely used in many energy-related fields, including consumer electronics, new energy vehicles, large-scale energy storage power stations, and portable smart devices. They are the core energy storage devices driving the upgrading of the modern new energy industry. Among the key components of lithium-ion batteries, the cathode material directly determines the overall energy density, rate charge / discharge performance, cycle life, and safety performance. It is the core material for improving the overall performance of batteries and breaking through existing application bottlenecks, and its performance optimization and technological iteration have always been a research focus in the fields of new energy materials and electrochemistry.

[0052] Spinel-type lithium manganese oxide (LiMn2O4), as a classic cathode material, possesses multiple advantages, including abundant manganese resources, low raw material costs, excellent battery safety, and outstanding environmental friendliness, and has already achieved large-scale application in the lithium-ion battery field. However, this material has significant technical defects. During deep charge-discharge cycles or high-temperature operating environments, the material is prone to Jahn-Teller lattice instability, accompanied by the release of manganese ions (Mn2O4). 2+ The problem of dissolution and loss directly leads to a rapid decline in battery capacity and operating voltage, severely limiting its application in high energy density and long-endurance scenarios.

[0053] To overcome the performance limitations of traditional spinel-type LiMn2O4, high-voltage spinel-type lithium nickel manganese oxide (LNMO) cathode materials have emerged. This material, by introducing nickel to participate in high-potential redox reactions, raises the operating voltage platform of lithium-ion batteries to 4.7 V~4.9 V, far exceeding that of traditional lithium manganese oxide. Under the same volume and mass conditions, it can achieve higher energy density while maintaining good rate performance and safety. It has become a core candidate for next-generation high-energy-density, long-range lithium-ion battery cathode materials, possessing extremely high industrial application value and market prospects.

[0054] Despite the significant performance advantages of high-voltage LNMO cathode materials, under current preparation and modification techniques, this material still faces several prominent technical challenges in practical industrial applications, as follows: Firstly, there is the problem of irreversible phase transition and structural degradation. Under high voltage and high rate cycling conditions, the repeated insertion and extraction of lithium ions will induce the migration of lattice sites of transition metal ions such as nickel and manganese, causing the material to undergo an irreversible transformation from a stable spinel phase to an inert rock salt phase. During the transformation process, phase boundary stress and internal microcracks are generated, which gradually cause the loss of active material phase and ultimately lead to rapid capacity decay of the battery.

[0055] Secondly, there is the stress concentration problem caused by the two-phase reaction. The charging and discharging process of traditional LNMO materials is accompanied by obvious two-phase transformation behavior. During the multi-step phase transformation process, lattice parameter mismatch and interfacial energy accumulation can easily lead to cracking of material particles and collapse of the overall electrode structure, which greatly reduces the long-cycle stability of the battery.

[0056] Third, there are issues with high-potential interface side reactions and a surge in interface impedance. LNMO operates at a voltage as high as 4.9 V. Conventional carbonate electrolytes are prone to oxidative decomposition at this high potential, generating an unstable, high-impedance solid electrolyte interface layer on the surface of the material particles. This not only hinders the rapid transport of lithium ions but also further exacerbates the dissolution of transition metal ions, leading to a continuous increase in battery impedance and a significant reduction in cycle life.

[0057] To address the performance defects of LNMO cathode materials, existing technologies have developed various elemental doping modification strategies, mainly divided into two categories: The first category is single-element doping modification, which, by doping with single elements such as Cr, Nb, Fe, and P, can optimize the material's lattice structure and improve rate performance and short-term cycle stability to a certain extent. However, this type of doping can only achieve local defect pinning and has limited effect on the overall electrochemical reaction thermodynamics and phase transition path regulation of the material, and cannot fundamentally suppress irreversible phase transitions under high voltage. The second category is multi-element co-doping modification, including binary or ternary co-doping such as Li / F, Al / F, Nb / Ta, and Fe / Cr / Cu, which can improve the capacity retention rate of the material within a medium cycle range. However, existing co-doping systems are mostly limited to 1 to 3 element combinations. When the doping concentration is too low, it cannot completely change the material's phase transition mechanism, making it difficult to achieve breakthroughs in long-cycle stability. If the doping amount is increased, it is easy to cause a positive mixing enthalpy, induce phase separation, or internal stress concentration, which will affect the structural stability of the material and cannot simultaneously achieve high doping amount, single-phase structure, and uniform element distribution.

[0058] In summary, existing high-voltage LNMO cathode material modification technologies have significant limitations and have not yet achieved breakthroughs in core technologies. Key technical challenges that urgently need to be addressed for the industrial application of high-voltage LNMO cathode materials include: maintaining the single-phase structure and uniform elemental distribution while ensuring high doping levels; effectively suppressing the irreversible transformation from spinel to rock salt phase under harsh high-voltage, high-rate cycling conditions; and reconstructing traditional two-phase reactions into solid solution reactions with milder kinetics and lower stress, thus solving particle cracking and structural collapse problems. These are also the core directions for the research and development of next-generation high-energy-density lithium-ion battery cathode materials.

[0059] Based on this, embodiments of this application provide a positive electrode active material and its preparation method, a battery cell, and an electrical device. This positive electrode active material maintains a single-phase structure and uniform elemental distribution under high doping levels, while simultaneously suppressing the irreversible transformation of spinel to rock salt phase under high voltage and high rate cycling conditions, and reconstructing the two-phase reaction into a milder solid solution reaction. This results in a battery with excellent electrochemical performance.

[0060] Positive electrode active material This application provides a positive electrode active material, including Li a (Ni b Mn c M d )Q δ O 4-δ / 2The compound shown (abbreviated as HELNMO) has the following properties: 0.9 ≤ a ≤ 1.1, b > 0, c > 0, d > 0, b + c + d = 2, 0 ≤ δ ≤ 0.5, M includes at least three of Fe, Cr, Cu, Nb, Ti, Al, Mg, Zr, Sb, and Ga, and Q includes at least one of F and Cl. Figure 3 and Figure 4 As shown, the positive electrode active material has a crystal structure that can be classified into space group Fd-3m, and the cations of the transition metal sites in the crystal structure of space group Fd-3m are at least partially disordered.

[0061] As an example, 'a' can be 0.9, 0.92, 0.95, 0.98, 1, 1.02, 1.05, 1.08, 1.1, or any range of the above values.

[0062] Optionally, 0.3 ≤ b ≤ 0.5. As an example, b can be 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, or any range of the above values.

[0063] Optionally, 1.3 ≤ c ≤ 1.5. As an example, c can be 1.3, 1.32, 1.35, 1.38, 1.4, 1.42, 1.45, 1.48, 1.5, or any range of the above values.

[0064] Optionally, 0.03 ≤ d ≤ 0.4. As an example, d can be 0.03, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any range of the above values.

[0065] It should be noted that the at least partially disordered distribution of cations at transition metal sites refers to the situation in spinel-type crystal structures where transition metal cations, which originally had fixed occupancy rules at the lattice sites, break the conventional ordered coordination and occupancy mode. Different types of non-lithium cations exhibit a locally random arrangement and non-fixed occupancy at the dedicated transition metal sites within the lattice. Moreover, this disordered arrangement only covers part of the sites in the structure and is not the entire lattice completely disordered. It is a mixed arrangement structure with local order and local disorder.

[0066] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, in the examples of positive electrode active materials in this application, the molar O content is only a theoretical value. Oxygen release from the crystal lattice causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0067] According to the embodiments of this application, the positive electrode active material of this application adopts multi-element synergistic doping and anion site regulation modification. Relying on the crystal structure of space group Fd-3m, it achieves that the material still maintains a single-phase structure and the constituent elements are uniformly distributed even with high doping levels, solving the phase separation and element segregation problems that are prone to occur in traditional high-doped materials; at the same time, through structural regulation of the disordered distribution of the cation part of the transition metal site, see [reference]. Figure 5 and Figure 6 Under high voltage and high rate cycling conditions, it can effectively suppress the irreversible structural transformation from spinel phase to rock salt phase, block the generation pathway of phase boundary stress and particle microcracks, and reconstruct the violent two-phase reaction of traditional LNMO materials into a solid solution reaction with milder kinetics and smaller lattice strain, eliminating particle cracking and electrode structure collapse caused by lattice mismatch and interfacial energy accumulation. In addition, the special crystal structure and elemental composition of this material can optimize the stability of the electrode interface, alleviate the side reaction of electrolyte oxidation decomposition at high potential, reduce the dissolution of transition metal ions, and reduce the rate of interfacial impedance growth. Based on the dual optimization of the above structure and reaction mechanism, the secondary battery cell equipped with this positive electrode active material can have high energy density, excellent rate charge and discharge performance and cycle life.

[0068] Furthermore, a nickel content of 0.3 ≤ b ≤ 0.5 maintains the material's high voltage plateau and high energy density (4.7V~4.9V) while avoiding excessive nickel content that could exacerbate transition metal migration and structural distortion. A manganese content of 1.3 ≤ c ≤ 1.5 aligns with the ideal lattice coordination requirements of spinel-type materials, preserving the core advantages of low cost and high safety of manganese-based materials while also helping to suppress Jahn-Teller instability and Mn dissolution with doping elements. A doping content of 0.03 ≤ d ≤ 0.4 ensures that multi-valence doping elements fully exert their lattice stability and charge compensation functions without insufficient modification due to excessive doping or negative impact on the spinel framework of the material due to excessive doping. Combined with the disordered distribution of cations at transition metal sites, this effectively blocks the irreversible transformation from spinel to rock salt phase under high voltage and high-rate cycling conditions.

[0069] In some embodiments, M includes Fe, Cr, Cu and Nb, and the molar ratio of Fe, Cr, Cu and Nb is 1:(0.9~1.1):(0.9~1.1):(0.9~1.1). For example, the molar ratio of Fe, Cr, Cu and Nb can be 1:1:1:1, 1:0.9:0.9:0.9, 1:0.9:0.9:1, 1:0.9:1:0.9, 1:1:0.9:0.9:0.9, 1:1:1:0.9, 1:0.9:1:1, 1:1:0.9:1, 1:0.9:0.9:1.1, 1:0.9:1.1:0.9, 1:1.1:0.9:0.9:0.9, 1:1.1:1:0.9, 1:0.9:1.1:1.1, 1:1.1:0.9:1.1, 1:1.1:1.1:1.1, or any range of the above molar ratios.

[0070] In the above embodiments, the molar ratios of Fe, Cr, Cu, and Nb are nearly equal, which can achieve uniform occupancy of lattice sites and charge balance, avoiding lattice distortion and local stress concentration problems caused by excessive doping of a single element. At the same time, Fe can regulate the valence state of transition metals and suppress the Jahn-Teller effect, Cr can enhance the stability of the lattice framework and block irreversible phase transitions, Cu can optimize lithium-ion diffusion kinetics and improve rate performance, and Nb can passivate active sites on the material surface and alleviate interfacial side reactions. The four elements work together to exert the modification effects of lattice stability, charge compensation, and kinetic optimization in an all-round way. The modification effect will not be insufficient due to too low doping amount, nor will the spinel crystal framework of the material be affected by the imbalance of doping ratio.

[0071] In some embodiments, the configurational entropy S of the transition metal site conf Satisfy: 0.6R≤S conf ≤1.3R. As an example, S conf It can be a range of 0.6R, 0.7R, 0.8R, 0.9R, R, 1.1R, 1.2R, 1.3R, or any of the above values.

[0072] It should be noted that the configurational entropy S of the transition metal site conf S is a thermodynamic quantity that describes the degree of disorder resulting from the random distribution of transition metal atoms at specific lattice sites. conf = R∑x i lnx, where x i R represents the mole fractions of Ni, Mn, and M occupying transition metal sites, and R is the gas constant.

[0073] Alternatively, 0.7R≤S conf ≤1.3R, 0.8R≤S conf≤1.3R, 0.8R≤S conf ≤1.2R, 0.8R≤S conf ≤1.1R, 0.8R≤S conf ≤1.0R.

[0074] In the above embodiments, the configurational entropy S of the transition metal site conf Satisfy: 0.6R≤S conf At ≤1.3R, the stability of the disordered distribution of transition metal cations can be enhanced through entropy stabilization effect, ensuring that the material is in a high-entropy or near-high-entropy state. This is beneficial for stabilizing a single solid solution phase, offsetting the driving force of ion migration under high-voltage cycling, and suppressing the irreversible transformation from spinel phase to rock salt phase. It can also reduce the risk of element segregation and phase separation caused by excessively low configuration entropy, as well as the problems of excessive lattice disorder and main structure collapse caused by excessively high configuration entropy, thus precisely balancing lattice stability and ion transport efficiency. Combined with the configuration entropy regulation effect, the violent two-phase reaction of traditional LNMO can be further reconstructed into a solid solution reaction with mild kinetics and minimal lattice strain, eliminating the problems of particle cracking and structural collapse caused by lattice mismatch and interfacial energy accumulation.

[0075] Furthermore, the configurational entropy S of the transition metal sites conf Satisfying: 0.8R≤S conf At ≤1.0R, it can further balance the stability of the crystal structure, ion transport kinetics and charge transport efficiency; combined with the entropy regulation effect of this superior configuration, it can further reconstruct the violent two-phase reaction during the charging and discharging process of traditional LNMO materials into a solid solution reaction with milder kinetics and negligible lattice strain, and completely eliminate the problems of lattice mismatch and interface energy accumulation caused by multi-step phase transition.

[0076] In some embodiments, the average particle size of the positive electrode active material is 0.5 μm to 20 μm. As an example, the average particle size of the positive electrode active material can be 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, or any range of the above values.

[0077] In some embodiments, the operating platform voltage of the positive electrode active material is 4.6V~4.8V.

[0078] Preparation method of positive electrode active material This application provides a method for preparing a positive electrode active material, including: The Li source, Ni source, Mn source, M source and Q source are mixed in a predetermined ratio and then ground to obtain a precursor slurry. The molar ratio of Ni to M in the precursor slurry is 0.7~17 and the molar ratio of Mn to M is 3~50.

[0079] After drying the precursor slurry, precursor powder is obtained.

[0080] The precursor powder is subjected to tableting, sintering and pulverizing processes in sequence to obtain the positive electrode active material of the first aspect.

[0081] As an example, the molar ratio of Ni to M in the precursor slurry can be 0.7, 1, 3, 5, 7, 9, 11, 13, 15, 17, or any range of the above values.

[0082] As an example, the molar ratio of Mn to M in the precursor slurry can be 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or any range of the above values.

[0083] According to the embodiments of this application, the preparation method eliminates the complex post-coating processing steps required for conventional modified LNMO materials, saving multiple additional steps such as coating agent preparation, coating treatment, and secondary heat treatment, significantly shortening the overall preparation cycle. The process flow is extremely simple, and the ease of operation is greatly improved. It can also effectively ensure the uniformity of elemental distribution, crystal structure consistency, and electrochemical performance stability of different batches of products, avoiding performance fluctuations between batches, and effectively reducing production energy consumption and raw material loss, controlling the cost of large-scale production. The overall process has strong compatibility, low scale-up difficulty, and no complex process bottlenecks, showing excellent prospects for pilot-scale amplification and continuous industrial production.

[0084] In some embodiments, in the step of mixing Li source, Ni source, Mn source, M source and Q source in a predetermined ratio and then grinding them to obtain a precursor slurry, the grinding process is wet ball milling, and the ball milling speed is 200 r / min to 400 r / min. As an example, the ball milling speed can be 200 r / min, 220 r / min, 250 r / min, 280 r / min, 300 r / min, 320 r / min, 350 r / min, 380 r / min, 400 r / min, or any range of the above values.

[0085] In some embodiments, in the step of mixing Li source, Ni source, Mn source, M source and Q source in a predetermined ratio and then grinding them to obtain a precursor slurry, the grinding time is 8h to 24h. As an example, the grinding time can be 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any range of the above values.

[0086] In some embodiments, the Li source can be one or more of lithium oxides, lithium hydroxide, and lithium salts. Lithium oxides include, but are not limited to, Li₂O. The anions generated by the ionization of the lithium salt include, but are not limited to, one or more of oxalate ions, carbonate ions, sulfate ions, nitrate ions, acetate ions, halide ions, phosphate ions, and dihydrogen phosphate ions. Examples of lithium salts include one or more of lithium carbonate, lithium sulfate, lithium nitrate, lithium acetate, lithium dihydrogen phosphate, lithium phosphate, and lithium oxalate. In some embodiments, the lithium source is one or more of lithium carbonate, lithium nitrate, lithium hydroxide, and lithium acetate.

[0087] In some embodiments, the Ni source may include one or more of Ni(OH)2, NiCO3, NiO, Ni(NO3)2·6H2O, and NiC2O4.

[0088] In some embodiments, the Mn source may include one or more of Mn(OH)2, MnCO3, MnO2, Mn3O4, Mn(NO3)2·4H2O and Mn(CH3COO)2·4H2O.

[0089] In some embodiments, the Fe source may include one or more of Fe(OH)3, FeOOH, Fe2O3, Fe3O4, and Fe(NO3)3·9H2O.

[0090] In some embodiments, the Cr source may include one or more of Cr(OH)3, Cr2O3 and Cr(NO3)3·9H2O.

[0091] In some embodiments, the Cu source may include one or more of Cu(OH)2, CuCO3, CuO, and Cu(NO3)2·3H2O.

[0092] In some embodiments, the Nb source may include one or more of Nb2O5, Nb(OH)5, and NbCl5.

[0093] In some embodiments, the Ti source may include one or more of TiO2, Ti(OH)4 and Ti(OC4H9)4.

[0094] In some embodiments, the Al source may include one or more of Al(OH)3, AlOOH, Al2O3 and Al(NO3)3·9H2O.

[0095] In some embodiments, the Mg source may include one or more of Mg(OH)2, MgCO, MgO and Mg(NO3)2·6H2O.

[0096] In some embodiments, the Zr source may include one or more of ZrO2, Zr(OH)4, and ZrO(NO3)2·2H2O.

[0097] In some embodiments, the Sb source may include one or more of Sb2O3, Sb2O, and Sb(OH)3.

[0098] In some embodiments, the Ga source may include Ga2O3 and / or Ga(NO3)·xH2O.

[0099] In some embodiments, the F source can be one or more of LiF, NH4F, NH4HF2, MnF2, NiF2, CoF2, NaF, and KF.

[0100] In some embodiments, Cl can be one or more of LiCl, NH4Cl, MnCl2, NiCl2, FeCl3, NaCl, and KCl.

[0101] In some embodiments, the Li source is in excess of 3-10 mol% relative to the stoichiometric ratio to compensate for the volatilization of lithium during high-temperature sintering.

[0102] In some embodiments, in the step of mixing Li source, Ni source, Mn source, M source and Q source in a predetermined ratio and then grinding them to obtain a precursor slurry, the ratio of the sum of the masses of Li source, Ni source, Mn source, M source and Q source to the mass of the grinding media used in the grinding process is 1:(5~20). As an example, it can be 1:5, 1:8, 1:10, 1:12, 1:15, 1:20, or any range of the above values.

[0103] In some embodiments, in the step of drying the precursor slurry to obtain precursor powder, the drying temperature is 60°C to 120°C. For example, it can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any range of the above values.

[0104] In some embodiments, in the step of drying the precursor slurry to obtain the precursor powder, the drying time is 8h to 24h. For example, it can be 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any range of the above values.

[0105] In some embodiments, in the step of sequentially subjecting the precursor powder to tableting, sintering, and pulverizing to obtain the positive electrode active material of the first aspect, the tableting pressure is 2 MPa to 20 MPa. For example, it can be 2 MPa, 5 MPa, 8 MPa, 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa, or any range of the above values.

[0106] In some embodiments, in the step of sequentially subjecting the precursor powder to tableting, sintering, and pulverizing to obtain the positive electrode active material of the first aspect, the holding time for tableting is 1 min to 3 min. For example, it can be 1 min, 1.2 min, 1.5 min, 1.8 min, 2 min, 2.2 min, 2.5 min, 2.8 min, 3 min, or any range of the above values.

[0107] In some embodiments, in the step of sequentially performing tableting, sintering and pulverizing of the precursor powder to obtain the positive electrode active material of the first aspect, the sample after tableting is a disc or a block.

[0108] In some embodiments, in the step of sequentially subjecting the precursor powder to tableting, sintering, and pulverizing to obtain the positive electrode active material of the first aspect, the heating rate of the sintering process is 3°C / min to 10°C / min. For example, it can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range of the above values.

[0109] In some embodiments, in the step of sequentially subjecting the precursor powder to tableting, sintering, and pulverizing to obtain the positive electrode active material of the first aspect, the sintering temperature of the sintering process is 750°C to 900°C. For example, it can be 750°C, 780°C, 800°C, 820°C, 850°C, 880°C, 900°C, or any range of the above values.

[0110] In some embodiments, in the step of sequentially subjecting the precursor powder to tableting, sintering, and pulverizing to obtain the positive electrode active material of the first aspect, the holding time for the sintering process is 12h to 24h. For example, it can be 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any range of the above values.

[0111] Secondary battery cell This application provides a secondary battery cell, including a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode to isolate the positive electrode and the negative electrode.

[0112] The positive electrode includes a current collector and a positive active material layer disposed on at least one side of the current collector. The positive active material layer includes the above-described positive active material and / or the positive active material prepared by the above-described preparation method.

[0113] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0114] In some embodiments, after 1000 cycles at a voltage range of 3.2 V to 4.9 V and a 2 C rate, the capacity retention of a single secondary battery cell is greater than or equal to 75%, and the specific capacity is greater than or equal to 120 mAh·g. -1 .

[0115] In some embodiments, the negative electrode may include a negative current collector.

[0116] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0117] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0118] In some embodiments, this application does not have any particular limitation on the type of separator membrane, and any well-known porous structure separator membrane with good chemical and mechanical stability can be selected.

[0119] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0120] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0121] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0122] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0123] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0124] In some embodiments, the electrode assembly has tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0125] In this embodiment of the application, the lithium-ion battery cell can be a secondary battery cell, which refers to a battery cell that can be recharged after being discharged to activate the active material and continue to be used.

[0126] A typical secondary battery cell includes an electrode assembly. The electrode assembly consists of a positive electrode and a negative electrode. During the charging and discharging process of the battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes.

[0127] In some embodiments, the secondary battery cell may further include an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel-like, or solid.

[0128] Liquid electrolytes include electrolyte salts and solvents.

[0129] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0130] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0131] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0132] In some embodiments, the secondary battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc.

[0133] In some embodiments, the housing may be a sealed structure or an unsealed structure.

[0134] As an example, when the outer casing is a non-sealed structure, it serves to protect the electrode assembly. A sealing bag may also be included between the outer casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the outer casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0135] In some embodiments, the housing includes an end cap and a housing, the housing having an opening, and the end cap covering the opening. The housing may have one or more openings. The end cap may also be provided with one or more.

[0136] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0137] Preparation method of secondary battery cell The methods for preparing battery cells are well known. For example, the assembly methods of battery cells include, but are not limited to, hard-shell batteries and soft-pack batteries.

[0138] In this application, the samples for testing the positive electrode active material can be taken directly from the positive electrode or sampled from a secondary battery cell. When sampling from a secondary battery cell, the liquid lithium metal battery cell is fully discharged, and then the secondary battery cell is disassembled to obtain the positive electrode film. The positive electrode film is further separated to obtain the positive electrode active material. Then, the positive electrode active material is characterized using a high-resolution transmission electron microscope to obtain the elemental characteristics of the positive electrode active material, and the crystal form of the positive electrode active material is characterized using an X-ray diffractometer.

[0139] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0140] Example 1-1 A positive electrode active material is prepared by the following steps: In step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, and niobium pentoxide are mixed to obtain 5g of mixed raw material. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Nb in the mixed raw material is 1.05:0.425:1.375:0.05:0.05:0.05:0.05.

[0141] In step S200, the above-mentioned mixed raw materials are added to a ball mill jar, 3.5 mL of anhydrous ethanol is added as a dispersion medium, and zirconia balls are added as grinding media. Wet ball milling is performed at a speed of 400 r / min and a milling time of 12 h. The mass ratio of the mixed raw materials to the grinding media is 1:10 to obtain a mixed slurry.

[0142] In step S300, the above-mentioned mixed slurry is dried in a drying device at a drying temperature of 100°C for a preferred drying time of 12 hours, and a uniformly mixed precursor powder is obtained after drying.

[0143] In step S400, the precursor powder is loaded into a mold and pressed into a block sample under a pressure of 10 MPa for 3 minutes.

[0144] In step S500, the above-mentioned block sample is placed in a corundum crucible and sintered in a muffle furnace with an air atmosphere. The heating rate is 5℃ / min; the sintering temperature is 850℃; and the holding time is preferably 18h. After the holding time, the furnace temperature is lowered to below 200℃, and then naturally cooled to room temperature. A block product is obtained.

[0145] In step S600, the above-mentioned blocky product is taken out, ground into powder, and sieved through a 200-400 mesh sieve to obtain LiNi. 0.425 Mn 1.375 Fe 0.05 Cr 0.05 Cu 0.05 Nb 0.05 O4.

[0146] Examples 1-2 The difference between Examples 1-2 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, and lithium fluoride are mixed to obtain 5g of mixed raw materials, and the molar ratio of Li:Ni:Mn:Fe:Cr:Cu:F in the mixed raw materials is 1.05:0.425:1.375:0.05:0.05:0.05:0.2.

[0147] Examples 1-3 The difference between Examples 1-3 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, and titanium dioxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Ti in the mixed raw materials is 1.05:0.425:1.395:0.05:0.05:0.05:0.03.

[0148] Examples 1-4 The difference between Examples 1-4 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, and magnesium oxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Mg in the mixed raw materials is 1.05:0.375:1.425:0.05:0.05:0.05:0.05.

[0149] Examples 1-5 The difference between Examples 1-5 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, and antimony pentoxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Sb in the mixed raw materials is 1.05:0.425:1.405:0.05:0.05:0.05:0.02.

[0150] Examples 1-6 The difference between Examples 1-6 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, ferric oxide, chromium oxide, copper oxide, and aluminum oxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Al in the mixed raw materials is 1.05:0.425:1.375:0.05:0.05:0.05:0.05.

[0151] Examples 1-7 The difference between Examples 1-7 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, and copper oxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu in the mixed raw materials is 1.05:0.2:1.65:0.05:0.05:0.05.

[0152] Examples 1-8 The difference between Examples 1-8 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, niobium pentoxide, and titanium dioxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Nb:Ti in the mixed raw materials is 1.05:0.4:1.35:0.05:0.05:0.05:0.05:0.05.

[0153] Examples 1-9 The difference between Examples 1-9 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, copper oxide, niobium pentoxide, titanium dioxide, and Al source are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu:Nb:Ti:Al in the mixed raw materials is 1.05:0.4:1.0:0.1:0.1:0.1:0.1:0.1:0.1:0.1.

[0154] Examples 1-10 The difference between Examples 1-10 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide, and copper oxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu in the mixed raw materials is 1.05:0.27:1.7:0.01:0.01:0.01.

[0155] Examples 1-11 The difference between Examples 1-11 and Examples 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, chromium oxide and copper oxide are mixed to obtain 5g of mixed raw materials. The molar ratio of Li:Ni:Mn:Fe:Cr:Cu in the mixed raw materials is 1.05:0.47:1.5:0.01:0.01:0.01.

[0156] Comparative Example 1-1 The difference between Comparative Example 1-1 and Example 1-1 is that in step S100, lithium carbonate, nickel oxide, and manganese dioxide are mixed to obtain 5g of mixed raw materials, and the molar ratio of Li:Ni:Mn in the mixed raw materials is 1.05:0.5:1.5.

[0157] Comparative Examples 1-2 The difference between Comparative Examples 1-2 and Example 1-1 is that in step S100, lithium carbonate, nickel oxide, manganese dioxide, iron oxide, and chromium oxide are mixed to obtain 5g of mixed raw materials, and the molar ratio of Li:Ni:Mn:Fe:Cr in the mixed raw materials is 1.05:0.45:1.45:0.05:0.05.

[0158] Test section S conf Testing: After the lithium-ion battery was discharged at a constant current to 1C, the positive electrode was mechanically disassembled to obtain the positive electrode sheet. The positive electrode sheet was cleaned three times with diethyl carbonate and dried at 80℃ for 4 hours to obtain a positive electrode sheet sample. The positive electrode active material was peeled off from the positive electrode sheet. The specific elemental content and composition of the positive electrode active material were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS), and the S was calculated. conf .

[0159] The parameters of the positive electrode active material are detailed in Table 1.

[0160] Table 1. Parameters of Positive Electrode Active Materials

[0161] Example 2-1 CR2025 coin cells were prepared using the positive electrode active material of Example 1-1.

[0162] Positive electrode: 80 wt% of the positive electrode active material from Example 1-1, 10 wt% of conductive carbon black (AB), and 10 wt% of polyvinylidene fluoride (PVDF) were dispersed in an appropriate amount of N-methylpyrrolidone (NMP) and mixed to form a uniform slurry. This slurry was then coated onto aluminum foil and dried in a vacuum oven at 80°C for 12 hours. The dried electrode was cut into small circular pieces with a diameter of 12 mm to serve as the positive electrode, with an active material loading of 2 mg / cm².

[0163] Counter electrode: Lithium metal.

[0164] Electrolyte: 1 mol / L lithium hexafluorophosphate (LiPF6), 0.02 mol / L lithium difluorooxalate borate (LiDFOB), and solvent is a mixture of fluoroethylene carbonate (FEC), diethyl fluorocarbonate (FDEC) and hydrofluoroether (HFE) in a volume ratio of 1:3:1.

[0165] Diaphragm: Polyethylene-polypropylene microporous membrane (Cellgard 2300).

[0166] Button cell assembly: The above-mentioned positive electrode, counter electrode, electrolyte and separator are assembled into a CR2025 type button cell in a glove box filled with argon gas.

[0167] Example 2-2 The difference between Example 2-2 and Example 2-1 is that the positive electrode active material of Example 1-2 is used.

[0168] Example 2-3 The difference between Examples 2-3 and Examples 2-1 is that the positive electrode active material used in Examples 1-3 is selected.

[0169] Examples 2-4 The difference between Examples 2-4 and Examples 2-1 is that the positive electrode active material used in Examples 1-4 is selected.

[0170] Examples 2-5 The difference between Examples 2-5 and Examples 2-1 is that the positive electrode active material used in Examples 1-5 is selected.

[0171] Examples 2-6 The difference between Examples 2-6 and Examples 2-1 is that the positive electrode active material used in Examples 1-6 is selected.

[0172] Examples 2-7 The difference between Examples 2-7 and Examples 2-1 is that the positive electrode active material used in Examples 1-7 is selected.

[0173] Examples 2-8 The difference between Examples 2-8 and Examples 2-1 is that the positive electrode active material used in Examples 1-8 is selected.

[0174] Examples 2-9 The difference between Examples 2-9 and Examples 2-1 is that the positive electrode active material used in Examples 1-9 is selected.

[0175] Example 2-10 The difference between Example 2-10 and Example 2-1 is that the positive electrode active material of Example 1-10 is used.

[0176] Example 2-11 The difference between Example 2-11 and Example 2-1 is that the positive electrode active material of Example 1-11 is used.

[0177] Comparative Example 2-1 The difference between Comparative Example 2-1 and Example 2-1 is that the positive electrode active material of Comparative Example 1-1 is used.

[0178] Comparative Example 2-2 The difference between Comparative Example 2-2 and Example 2-1 is that the positive electrode active material used in Comparative Example 1-2 is selected.

[0179] Test section 1. First-cycle discharge capacity of liquid CR2025 button type The assembled coin cells were charged to 4.9V (Li) at a current density of 0.1C. + / Li), and then discharge to 3.0V at a current density of 0.1C, and record the discharge capacity C0 of the coin cell. The ratio of the first discharge capacity C0 of the coin cell to the weight of the positive electrode active material is taken as the first discharge capacity (mAh / g) of the coin cell.

[0180] 2. Cycle capacity retention rate of button cells The assembled coin cell was charged to 4.9V at a current density of 0.2C, and then discharged to 3.0V at a current density of 2C. The discharge capacity C0 of the coin cell was recorded. The individual cells were subjected to 1000 charge-discharge cycles in the same manner. The discharge capacity Cn of the coin cell after the 1000th cycle was recorded. The cycle capacity retention rate (%) of the coin cell was calculated as Cn / C0. 100%.

[0181] The test results are detailed in Table 2.

[0182] Table 2

[0183] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A positive electrode active material, characterized in that, Including compound Li a (Ni b Mn c M d )Q δ O 4-δ / 2 Wherein, 0.9≤a≤1.1, b>0, c>0, d>0, b+c+d=2, 0≤δ≤0.5, M includes at least three of Fe, Cr, Cu, Nb, Ti, Al, Mg, Zr, Sb and Ga, and Q includes at least one of F and Cl; The positive electrode active material has a crystal structure that can be classified into space group Fd-3m, and the cations of the transition metal sites in the crystal structure of space group Fd-3m are at least partially disordered.

2. The positive electrode active material according to claim 1, characterized in that, The positive electrode active material satisfies at least one of the following: （1）0.3≤b≤0.5； （2）1.3≤c≤1.5； （3）0.03≤d≤0.4。 3. The positive electrode active material according to claim 1, characterized in that, M includes Fe, Cr, Cu and Nb, and the molar ratio of Fe, Cr, Cu and Nb is 1:(0.9~1.1):(0.9~1.1):(0.9~1.1).

4. The positive electrode active material according to claim 1, characterized in that, The configurational entropy S of the transition metal site conf Satisfy: 0.6R≤S conf ≤1.3R, where R is the gas constant.

5. The positive electrode active material according to claim 4, characterized in that, 0.8R≤S conf ≤1.0R。 6. The positive electrode active material according to any one of claims 1 to 5, characterized in that, The positive electrode active material satisfies at least one of the following: (1) The average particle size of the positive electrode active material is 0.5 μm to 20 μm; (2) The working platform voltage of the positive electrode active material is 4.6V~4.8V.

7. A method for preparing a positive electrode active material, characterized in that, include: The Li source, Ni source, Mn source, M source and Q source are mixed in a predetermined ratio and then ground to obtain a precursor slurry. The molar ratio of Ni to M in the precursor slurry is 0.7 to 17 and the molar ratio of Mn to M is 3 to 50. After drying the precursor slurry, precursor powder is obtained. The precursor powder is subjected to tableting, sintering and pulverizing processes in sequence to obtain the positive electrode active material according to any one of claims 1 to 6.

8. The preparation method according to claim 7, characterized in that, The preparation method satisfies at least one of the following: (1) The grinding process is wet ball milling, and the ball milling speed is 200 r / min to 400 r / min; (2) The grinding process takes 8 hours to 24 hours; (3) The ratio of the sum of the masses of the Li source, Ni source, Mn source, M source and Q source to the mass of the grinding media in the grinding process is 1:(5~20); (4) The drying temperature is 60℃~120℃; (5) The drying time is 8h~24h; (6) The pressure of the tablet compression process is 2MPa~20MPa; (7) The holding time for the tableting process is 1 min to 3 min; (8) The heating rate of the sintering treatment is 3℃ / min~10℃ / min; (9) The sintering temperature of the sintering treatment is 750℃~900℃; (10) The heat preservation time of the sintering treatment is 12h~24h.

9. A secondary battery cell, characterized in that, It includes the positive electrode active material according to any one of claims 1 to 6 and / or the active material prepared by the preparation method according to any one of claims 7 to 8.

10. An electrical device, characterized in that, Includes the secondary battery cell as described in claim 9.

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