Lithium-rich manganese-based positive active material, positive plate and battery

Abstract

The invention provides a lithium-rich manganese-based positive electrode active material, a positive plate and a battery, the lithium-rich manganese-based positive electrode active material comprises secondary single-crystal-like particles formed by agglomeration of primary particles, the secondary single-crystal-like particles are formed by agglomeration of 2-10 primary particles, and the ratio of the average particle size of the secondary single-crystal-like particles to the average particle size of the primary particles is (2.5-10): 1; according to the monocrystal-like structure, by controlling the ratio of the average particle size of the primary particles to the average particle size of the secondary particles, the grain boundary defects are reduced, and the mechanical strength and interface compatibility of the material are improved. The lithium-rich manganese-based positive electrode active material is doped with an element W, an element P and an element F, the three doping elements stabilize an oxygen skeleton, inhibit transition metal migration and lattice oxygen loss and enhance the structural stability of the material through a synergistic effect, and meanwhile, the size distribution of primary particles can be regulated and controlled.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a lithium-rich manganese-based positive electrode active material, a positive electrode sheet, and a battery. Background Technology

[0002] Solid-state batteries, as a core technology of next-generation high-energy-density energy storage systems, offer significant advantages in terms of high safety and long cycle life. In solid-state batteries, the cathode material is a key factor determining the battery's energy density and cycle stability. Lithium-rich manganese-based cathode active materials, due to their high specific capacity and low cost, have become one of the preferred materials for solid-state batteries.

[0003] Currently, the most widely studied type of active material is the polycrystalline lithium-rich manganese-based cathode material. The smaller particle size and grain interface structure of polycrystalline materials provide more reaction areas, resulting in better performance at high charge-discharge rates. However, this type of lithium-rich manganese-based cathode active material has many internal pores and grain boundaries, making it difficult to form a large effective contact area with the solid electrolyte in solid-state batteries, thus severely affecting the capacity utilization of the solid-state battery. Furthermore, during cycling, stress concentration at the grain boundaries in polycrystalline lithium-rich manganese-based cathode active materials easily leads to intergranular cracking, resulting in rapid capacity decay.

[0004] Therefore, improving the structural stability of lithium-rich manganese-based cathode active materials during cycling is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a lithium-rich manganese-based cathode active material, a cathode sheet, and a battery, wherein the lithium-rich manganese-based cathode active material has good cycle stability.

[0006] In a first aspect, this application provides a lithium-rich manganese-based cathode active material, comprising secondary-like single-crystal particles formed from primary particles, wherein the ratio of the average particle size of the secondary-like single-crystal particles to the average particle size of the primary particles is (2.5~10):1.

[0007] The lithium-rich manganese-based positive electrode active material contains W, P and F elements.

[0008] The secondary single-crystal particles refer to those formed by the aggregation of 2 to 10 primary particles.

[0009] Furthermore, the ratio of the particle size Dv50 of the secondary single crystal particles to the average particle size of the secondary single crystal particles is (1.1~1.5):1;

[0010] And / or, the particle size distribution width (Span) of the secondary single-crystal particles is 0.8~1.5;

[0011] The span value is (Dv90-Dv10) / Dv50.

[0012] Furthermore, the average particle size of the primary particles is 200 nm to 500 nm;

[0013] And / or, the average particle size of the secondary single-crystal particles is 1~5μm;

[0014] And / or, the particle size Dv50 of the secondary single-crystal particles is 1~8μm;

[0015] And / or, the particle size Dv10 of the secondary single-crystal particles is 0.5~2.5μm;

[0016] And / or, the particle size Dv90 of the secondary single-crystal particles is 1.8~14μm.

[0017] Furthermore, the primary particle comprises a bulk matrix and a surface matrix, the surface matrix being located on at least a portion of the outer surface of the bulk matrix, the center of the primary particle being located in the bulk matrix, and the surface matrix of the primary particle containing the element P;

[0018] Preferably, the mass content of P element in the surface matrix of the primary particles is higher than the mass content of P element in the bulk matrix.

[0019] Furthermore, both the bulk matrix and the surface matrix of the primary particles contain W, F, and P elements;

[0020] Preferably, the F element is located at the lattice oxygen site of the primary particle;

[0021] Preferably, the W element is located at a lattice transition metal site of the primary particle.

[0022] The transition metal includes at least one of Ni, Co, and Mn.

[0023] Furthermore, the outer surface of the secondary single-crystal particles is covered with a first coating layer and a second coating layer, wherein the second coating layer partially covers the surface of the first coating layer.

[0024] The first covering layer includes W elements;

[0025] Preferably, the first coating layer includes at least one of tungsten oxide and lithium tungstate, and the second coating layer includes lithium aluminum titanium phosphate.

[0026] Preferably, the thickness of the first coating layer is 5-30 nm.

[0027] Preferably, the coverage of the second coating layer is 10-30%.

[0028] Furthermore, the W element has a mass fraction of 0.01–0.5 wt% in the secondary single-crystal particles;

[0029] And / or, the mass fraction of the P element in the secondary single-crystal-like particles is 0.02 to 0.8 wt%.

[0030] And / or, the mass fraction of the F element in the secondary single-crystal-like particles is 0.005 to 0.4 wt%; and / or, the chemical general formula of the lithium-rich manganese-based cathode active material is:

[0031] aLi2MnO3·(1-a)LiNi x Co y Mn z W d P b A k O e F c , where 0 < a < 1, 0 < x < 1, 0 ≤ y < 1, 0 < z < 1, 0 < b < 1, 0 < c < 2, 0 < d < 1, 0 < e < 2, A includes at least one of Al, Mg, Ti, Zr, Sr, B, Nb, Tb, Y, La, and 0 ≤ k < 1.

[0032] Furthermore, the specific surface area of the lithium-rich manganese-based cathode active material is 2.2 to 3.3 m 2 / g;

[0033] And / or, the tap density of the lithium-rich manganese-based cathode active material is 2.7 to 3.2 g / cc;

[0034] And / or, the powder conductivity of the lithium-rich manganese-based cathode active material is 6.23E -07 ~5.69E -05 S / cm.

[0035] In a second aspect, the present application provides a cathode sheet, which includes the lithium-rich manganese-based cathode active material described in any one of the above.

[0036] In a third aspect, the present application provides a battery, which includes the cathode sheet, anode sheet, and solid electrolyte layer described in the second aspect, and the solid electrolyte layer is disposed between the cathode sheet and the anode sheet.

[0037] Preferably, the solid electrolyte layer includes a stacked halide solid electrolyte layer and a sulfide solid electrolyte layer.

[0038] Preferably, the halide solid electrolyte layer is disposed on the side of the cathode sheet, and the sulfide solid electrolyte layer is disposed on the side of the anode sheet;

[0039] The halide solid electrolyte layer includes a halide solid electrolyte, and the halide solid electrolyte accounts for 20-60% by weight of the solid electrolyte layer.

[0040] The sulfide solid electrolyte layer includes a sulfide solid electrolyte, and the sulfide solid electrolyte accounts for 40-80% of the weight of the solid electrolyte layer.

[0041] The halide solid electrolyte includes: Li3YBr 5.7 F 0.3 Li7P3S 11 Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+ y S 12 At least one of Li6PS5X, wherein 0 < x < 1, M includes at least one of Ge, Si, and Sn; 0 < y < 1, X includes at least one of Cl, Br, and I;

[0042] The sulfide solid electrolyte includes at least one of Li6PS5Cl, Li3MCl6, Li3Ybr6, Li3ScF6, and Li3YF6, wherein M includes at least one of Y, In, Sc, and Er.

[0043] This application provides a lithium-rich manganese-based cathode active material, comprising secondary-like single-crystal particles formed by the agglomeration of primary particles. The secondary-like single-crystal particles refer to particles containing 2 to 10 primary particles. The lithium-rich manganese-based cathode active material is doped with three doping elements: P, W, and F. These three doping elements work synergistically to stabilize the oxygen framework, inhibit transition metal migration and lattice oxygen loss, and enhance the structural stability of the material. Furthermore, the synergistic effect of the three doping elements can also regulate the size distribution of the primary particles, making the ratio of the average particle size of the secondary-like single-crystal particles to the average particle size of the primary particles (2.5 to 10):1. By controlling the ratio of the average particle size of the primary particles to the secondary particles, grain boundary defects are reduced, and the mechanical strength and interfacial compatibility of the material are improved. Attached Figure Description

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0045] Figure 1 This is a scanning electron microscope image of the lithium-rich manganese-based positive electrode active material of Example 2;

[0046] Figure 2 The elemental distribution diagram is shown in the grain cross-section of the lithium-rich manganese-based cathode active material in Example 2.

[0047] Figure 3This is a schematic diagram of the EDS line scan of the grain profile of the lithium-rich manganese-based cathode active material in Example 2;

[0048] Figure 4 This is an EDS line scan image of the grain profile of the lithium-rich manganese-based cathode active material in Example 2;

[0049] Figure 5 The image shows a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material in Comparative Example 1.

[0050] Figure 6 This is a scanning electron microscope image of the lithium-rich manganese-based cathode active material in Comparative Example 2.

[0051] Figure 7 The image shows a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material in Comparative Example 3.

[0052] Figure 8 This is a schematic diagram of the structure of an all-solid-state battery.

[0053] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0055] This application designs a near-single-crystal lithium-rich manganese-based active material composed of primary particles. By designing a near-single-crystal lithium-rich manganese-based cathode active material, the grain boundary distribution and particle structure of the material are optimized, reducing intergranular stress concentration and improving the structural stability and cycle life of the material. Synergistic doping with P, W, and F elements suppresses oxygen release and transition metal migration. Through the synergistic effect of these three elements, the average particle size of the primary particles is controlled within a certain range, shortening the lithium-ion diffusion path, significantly optimizing lithium-ion transport efficiency, and improving the specific capacity of the material. Simultaneously, the three elements also improve the dispersion of the primary particles, reducing the likelihood of excessive adhesion, exposing more active sites, and ensuring more sufficient contact with the solid electrolyte. This helps improve the battery's discharge specific capacity, and sufficient contact also reduces material degradation caused by incomplete reactions in localized areas, thus improving the battery's cycle life.

[0056] The first aspect of this application provides a lithium-rich manganese-based cathode active material, which consists of secondary-like single-crystal particles formed by the agglomeration of primary particles, wherein the ratio of the average particle size of the secondary-like single-crystal particles to the average particle size of the primary particles is (2.5~10):1.

[0057] Secondary single-crystal particles refer to particles formed by the aggregation of 2 to 10 primary particles.

[0058] The lithium-rich manganese-based cathode active material is doped with W, P and F elements.

[0059] Lithium-rich manganese-based cathode active materials are secondary-like single-crystal particles, composed of 2-10 primary particles. Therefore, these secondary-like single-crystal particles also exhibit a highly consistent crystallographic orientation. Compared to traditional secondary sphere structures, the near-single-crystal structure reduces grain boundary defects, preventing stress concentration at grain boundaries and crack propagation, thereby improving the material's structural stability during cycling. Furthermore, the near-single-crystal design reduces the number of grain boundaries, improving the material's mechanical strength and compaction density. Increased compaction density optimizes the contact area between the cathode material and the solid electrolyte, shortening the lithium-ion transport path and reducing interfacial impedance.

[0060] The lithium-rich manganese-based cathode active material is doped with W, P, and F elements, W 6+ The high valence state of phosphorus can suppress transition metal migration, maintain the stability of the layered structure, thereby reducing particle cracking caused by phase transitions during cycling, inducing denser crystallization, and thus resulting in a higher compaction density of the material. Phosphorus (P) forms PO4 tetrahedral units in the bulk phase, effectively suppressing the collapse of the transition metal layer and the irreversible phase transition from the layered phase to the spinel phase during deep delithiation. Fluorine (F) doping alters the surface energy of the primary particles, promoting anisotropic growth. Co-doping with W, P, and F cations and anions stabilizes the lattice oxygen structure, prevents oxygen loss, enhances structural stability, and improves cycling performance.

[0061] The number of primary particles within secondary single-crystal particles ranges from 2 to 10, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or any combination of both. A smaller number of grain boundaries significantly reduces stress concentration and crack formation at the interface, thus improving cycle life. Secondary particles composed of a few grains more closely resemble the ideal single-crystal structure, providing a continuous and less resistant diffusion path for lithium ions.

[0062] The average particle size of secondary single-crystal particles is obtained by measurement under a electron microscope (SEM). The particle size of each secondary single-crystal particle is measured from its SEM image, and the average particle size of the primary particles is calculated. The ratio of the average particle size of the secondary single-crystal particles to the average particle size of the primary particles is (2.5~10):1, for example, 2.5:1, 3.5:1, 5.5:1, 6.5:1, 7.5:1, 8.5:1, 10:1, or any combination of these. A ratio greater than 2.5:1 is beneficial for increasing the compaction density of the material, improving the energy density of the battery, and improving the contact between the electrode material and the electrolyte; a ratio less than 10:1 is beneficial for reducing the number of surface grain boundaries, improving the structural stability of the material, reducing deformation and crack propagation during battery cycling, and improving the cycle life of the battery.

[0063] In some embodiments, the ratio of the particle size Dv50 of the secondary single-crystal particles to the average particle size of the secondary single-crystal particles is (1.1~1.5):1, for example, 1.1:1, 1.15:1, 1.2:1, 1.3:1, 1.5:1, or any combination thereof. Controlling the ratio within the range of (1.1~1.5):1 results in more uniform particle size of the secondary particles in the material, reduces porosity during the preparation of molded battery sheets, increases compaction density, optimizes lithium-ion transport kinetics, improves interface stability, and enhances cycle stability.

[0064] In some embodiments, the average particle size of the secondary single-crystal particles is 1~5μm, for example, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 5μm, or any combination thereof. Secondary particles within this particle size range can reduce pulverization or cracking problems that may be caused by small particles in the material, thereby improving the mechanical strength and structural stability of the material. Due to their single-crystal structure, secondary single-crystal particles can withstand greater stress and exhibit better stability during multiple charge-discharge cycles, reducing battery degradation.

[0065] In one specific implementation, the particle size Dv50 of the secondary single-crystal particles is 1~8μm, for example, 1.0μm, 2.0μm, 4.0μm, 6.0μm, 8.0μm, or any combination thereof. The particle size Dv50 and average particle size of the secondary single-crystal particles being within this range is beneficial in two ways: firstly, it provides a larger specific surface area and higher reactivity, which helps to improve the charge / discharge rate and energy density of the battery; secondly, the uniform particle size distribution of the secondary single-crystal particles, ensuring that the ratio of the particle size Dv50 to the average particle size is within (1.1~1.5):1, can improve interface stability and enhance cycle performance.

[0066] In some embodiments, the particle size Dv10 of the secondary single-crystal particles is 0.5~2.5μm, for example, 0.5μm, 1.00μm, 1.50μm, 2.00μm, 2.50μm, or any combination thereof. In some embodiments, the particle size Dv90 of the secondary single-crystal particles is 1.8~14μm, for example, 1.8μm, 3.1μm, 5.0μm, 7.5μm, 11.75μm, 14μm, or any combination thereof. The particle sizes Dv10 and Dv90 of the secondary single-crystal particles are within this range to ensure a relatively uniform particle size distribution.

[0067] In some embodiments, the particle size distribution width (span) of the secondary single-crystal particles is 0.8 to 1.5, for example, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or any combination thereof. The span value is calculated as (Dv90 - Dv10) / Dv50. A span of 0.8 to 1.5 results in a concentrated particle size distribution, avoiding stress concentration in large particles or excessive reaction in small particles during charge-discharge cycles, thereby reducing microcrack formation. This can optimize the processing performance (coating, compaction), electrochemical performance (rate capability, polarization), and structural stability (cycle life) of lithium-rich manganese-based materials.

[0068] In some embodiments, the average particle size of the primary particles is 200 nm to 500 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 500 nm, or any combination thereof. Within this range, it is advantageous to provide a larger specific surface area and higher reactivity, which helps to improve the charge / discharge rate and energy density of the battery.

[0069] Primary crystals consist of a bulk matrix and a surface matrix. The center of a primary crystal is located in the bulk matrix, which is the main body of the crystal. In the bulk matrix, atoms are arranged in a regular pattern to form a crystal structure. The surface matrix has a basically the same structure as the bulk matrix and is located at least part of the surface of the primary crystal, in contact with the external environment. Secondary single-crystal crystals are formed by multiple primary crystals, and the interface between two different primary crystals is called a grain boundary.

[0070] In one embodiment, the grain boundaries contain W, P and F elements. Including these three doping elements at the grain boundaries can improve the stability of the grain boundaries and prevent primary particle detachment.

[0071] In one embodiment, the P content at the grain boundary surface is greater than the P content in the primary particulate bulk matrix. High phosphorus (P) content at grain boundary surfaces can hinder the excessive growth of primary and secondary grains, thus reducing grain size.

[0072] In some embodiments, W is primarily a bulk dopant, P is mainly a bulk dopant and enriched at grain boundaries on the material surface, and F is primarily a bulk dopant. Specifically, W is doped at the transition metal sites of the lithium-rich manganese-based cathode active material, and F is doped at the oxygen sites of the lithium-rich manganese-based cathode active material. The bulk-doped P is doped at the tetrahedral positions of oxygen, as PO4. 3- The doping occurs in the form of phosphorus, without substituting oxygen or transition metal sites. Some phosphorus (P) is present at the grain boundaries of the primary particles in the lithium-rich manganese-based cathode active material. Fluorine (F) primarily substitutes for oxygen anions. Aberration-corrected electron microscopy (AEM) reveals that W is doped at transition metal sites and F is doped at O ​​sites in the cathode active material.

[0073] The type of doping element is related to the morphology of the material. When phosphorus (P) is doped into the material, it raises the energy barrier for oxygen to escape from the crystal lattice, and the [PO4] tetrahedral units can effectively suppress the collapse of the transition metal layer and the irreversible phase transition from the layered phase to the spinel phase during deep delithiation. P enrichment on the surface of primary particles (i.e., higher P content at grain boundaries) can hinder the excessive growth of secondary grains, reducing particle size and forming more uniform nano- or submicron-sized particles. This results in a narrower particle size distribution and reduces the formation of large agglomerates. 6+ The high valence state of fluorine can suppress transition metal migration, maintain the stability of the layered structure, thereby reducing particle cracking caused by phase transformation during cycling, inducing denser crystallization, and thus resulting in a higher compaction density of the material. fluorine (F) is distributed in the material as a bulk dopant. - O in the substitution lattice 2- These elements alter the surface energy of the material, promoting anisotropic growth. The synergistic effect of these three elements controls the average primary particle size within a certain range, shortening the lithium-ion diffusion path, significantly optimizing lithium-ion transport efficiency, and improving the material's specific capacity. Furthermore, the synergistic effect of these three elements suppresses structural collapse and phase transitions during cycling, significantly enhancing the material's long-term cycling stability.

[0074] The doping of the three elements improves the dispersion of the primary particles, making them less prone to agglomeration, exposing more active sites, and allowing for more thorough contact with the solid electrolyte.

[0075] In some embodiments, the mass content of P element on the surface of primary particles is greater than the mass content of P element in the bulk phase of primary particles. This structural change can be detected by EDS line scanning, as detailed in the test diagrams characterized in subsequent embodiments. This structure is more conducive to the formation of uniform particle structures and reduces the formation of large-sized agglomerates.

[0076] The amount of the doping element also affects the average primary particle size, dispersion, and electrochemical performance of the material. If the doping amount of the three elements is too small, the effect of dispersing the primary particles is weakened. If the doping element is excessive, it will lead to the addition of too many inert elements, resulting in a decrease in capacity. Therefore, the content of the doping element should be within a certain range.

[0077] In a specific implementation, the mass fraction of element W in the secondary quasi-single crystal particles is 0.1-0.5 wt%, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or the range composed of any two of the above. The doping amount within the range of 0.1-0.5 wt% can balance the stability effect of element W and the overall performance of the material, and avoid excessive W elements from affecting the energy density and power density of the lithium-ion battery.

[0078] In a specific implementation, the mass fraction of element P in the secondary quasi-single crystal particles is 0.2-0.8 wt%, such as 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, or the range composed of any two of the above; doping element P can improve the performance of the material during multiple cycles and reduce capacity fade. Within the range of 0.2-0.8 wt%, the doping of element P can maintain the structural stability while avoiding inhibiting the diffusion of lithium ions, ensuring good cycle performance of the battery.

[0079] In a specific implementation, the mass fraction of element F in the secondary quasi-single crystal particles is 0.05-0.4 wt%, for example, 0.05 wt%, 0.1 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or the range composed of any two of the above. The doping of element F can change the surface energy on the surface of the primary particles, promote anisotropic growth, and make the particles more uniform. The doping of element F within this range helps to reduce grain boundary defects, prevent grain boundary stress concentration while reducing crack propagation, thereby improving the cycle performance.

[0080] In some embodiments, the chemical general formula of the lithium-rich manganese-based cathode active material is:

[0081] aLi2MnO3·(1-a)LiNi x Co y Mn z W d P b A k O e F c , where 0 < a < 1, 0 < x < 1, 0 ≤ y < 1, 0 < z < 1, 0 < b < 1, 0 < c < 2, 0 < d < 1, 0 < e < 2, A includes at least one of Al, Mg, Ti, Zr, Sr, B, Nb, Tb, Y, La, and 0 ≤ k < 1.

[0082] In some embodiments, the surface of the secondary single-crystal particles includes a coating layer. In one specific implementation, the coating layer includes a first coating layer and a second coating layer. The first coating layer includes a tungsten-containing compound, which may be tungsten oxide or lithium tungstate, and the second coating layer is lithium aluminum titanium phosphate (LATP). The LATP partially coats the surface of the tungsten-containing compound.

[0083] The first coating layer, consisting of tungsten oxide and / or lithium tungstate, exhibits high chemical stability and can act as a barrier layer against oxygen loss, suppressing the release of lattice oxygen from lithium-rich materials under high voltage. This effectively inhibits side reactions at the interface and enables the construction of fast lithium-ion channels, enhancing lithium-ion conduction and reducing the interfacial impedance between the cathode material and the solid electrolyte. Furthermore, tungsten oxide has a wide band gap, which can effectively block the migration of electrons from the cathode to the solid electrolyte, reducing the formation of lithium dendrites at the interface.

[0084] The second coating layer, LATP, has high ionic conductivity, which can further improve the overall conductivity of the material, thereby reducing polarization loss, increasing the utilization rate of active substances, and enhancing interfacial stability, thus further improving the electrical properties of the material.

[0085] This application also provides a method for preparing a lithium-rich manganese-based cathode active material, comprising the following steps:

[0086] Step 1: Mix alkaline solutions of tungsten and phosphorus sources with a transition metal source to obtain a hydroxide precursor.

[0087] Step 2: Mix the hydroxide precursor, lithium source, and fluorine source and then calcine to obtain lithium-rich manganese-based cathode active material.

[0088] Optionally, step 3 is also included: mixing lithium-rich manganese-based cathode substrate active material with a tungsten source and sintering a tungsten-containing first coating layer on the surface of the material.

[0089] Step 4: Mix the lithium-rich manganese-based cathode active material of the first coating layer with LATP, and sinter the second coating layer.

[0090] In one specific implementation, in step 1, a sulfate solution containing Ni, Co, and Mn is co-precipitated with a mixed alkaline solution containing P and W (containing NaOH and NH3·H2O) in a reaction vessel to form a P and W-doped hydroxide precursor. The pH of the mixed reaction can be 11.5, and the temperature can be 50°C.

[0091] In a specific implementation, in step 2, the obtained hydroxide precursor doped with P and W is calcined in two stages (550 °C / 5 h + 880 °C / 12 h) in an air stream together with a mixture of Li source (LiOH) and LiF. LiF acts as a flux to promote element diffusion, achieving bulk doping of P, W, and F to form a lithium-rich manganese-based cathode active material.

[0092] In a specific implementation, in step S3, the lithium-rich manganese-based cathode active material obtained in step 2 is mixed with an ammonium source solution (such as ammonium tungstate) and then spray-dried, and calcined at 600 °C for 10 h in an air stream to form a tungsten oxide coating layer (with a thickness of 5 - 30 nm).

[0093] In a specific implementation, in step S4, the material obtained in step 3 is mixed with LATP and then calcined at 300 °C for 10 h in an air stream to form a dot-like distributed LATP coating layer. The high ionic conductivity of LATP constructs a fast lithium-ion channel, reducing the interfacial impedance of the solid-state battery.

[0094] The chemical general formula of the hydroxide precursor obtained in step 1 is Ni x Co y Mn z M (1-x-y-z) (OH)2, where 0 ≤ x < z, 0 ≤ y < z, z < 1, and the M element contains two elements, P and W. The particle size of the hydroxide precursor D V is 1 - 6 μm, the surface area is 20 - 50 m 2 / g, and the precursor morphology is mainly composed of small particles. In addition, the doping elements can regulate the morphology of the precursor. When doped with P alone, the precursor presents a块状 morphology, and the primary particles of the sintered product are prone to large-area agglomeration, affecting the specific capacity. When doped with W alone, the precursor morphology is a petal-like structure composed of sheet-like structures. When no doping is added, the precursor morphology presents a debris-like shape.

[0095] It should be noted that the Chinese character "块状" in the original text might be a misspelling. I translated it as "块状" according to the context. If it is incorrect, please provide the correct information for a more accurate translation.A first coating layer is formed by calcining a W compound and calcining a LATP compound. The tungsten oxide is coated onto the surface of a lithium-rich manganese-based substrate, while the LATP is uniformly distributed in a dotted pattern on the surface of the tungsten compound, forming a second coating layer. The tungsten oxide in the first coating layer exhibits high chemical stability and acts as a barrier against oxygen loss, suppressing lattice oxygen release from the lithium-rich material under high voltage. This effectively inhibits interfacial side reactions and creates rapid lithium-ion channels, enhancing lithium-ion conduction and reducing the interfacial impedance between the cathode material and the solid electrolyte. Furthermore, the wide band gap of tungsten oxide effectively blocks electron migration from the cathode to the solid electrolyte, reducing the formation of lithium dendrites at the interface. The second coating layer, LATP, is uniformly distributed on the first coating layer, primarily in a dotted pattern. LATP possesses high ionic conductivity, further improving the overall conductivity of the lithium-rich manganese-based cathode active material. This reduces polarization loss, increases the utilization rate of the active material, enhances interfacial stability, and further improves the material's electrical performance.

[0096] This application also provides a positive electrode sheet, which includes the above-mentioned lithium-rich manganese-based positive electrode active material, or includes the lithium-rich manganese-based positive electrode active material prepared by the above-mentioned preparation method.

[0097] The positive electrode sheet of this application specifically includes a positive current collector and a positive active layer formed of lithium-rich manganese-based positive active material disposed on the surface of the positive current collector.

[0098] In the specific preparation of the positive electrode sheet, for example, the lithium-rich manganese-based positive electrode active material of the present invention can be dispersed with a conductive agent and a binder in an appropriate amount of N-methylpyrrolidone (NMP) solvent, and thoroughly stirred to form a uniform positive electrode slurry; the positive electrode slurry is uniformly coated on the positive electrode current collector, and after drying, rolling and slitting, the positive electrode sheet is obtained. In one specific embodiment, the positive electrode active layer comprises, by mass percentage, 70-99 wt% of positive electrode active material, 0.5-15 wt% of conductive agent, and 0.5-15 wt% of binder, and further comprises 80-98 wt% of positive electrode active material, 1-10 wt% of conductive agent, and 1-10 wt% of binder.

[0099] The positive current collector can be made of at least one of aluminum foil or nickel foil; the conductive agent can be selected from at least one of carbon black, acetylene black, graphene, Ketjen black, and carbon fiber; and the binder can be selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, and polyurethane.

[0100] This application also provides a battery, which includes the above-described positive electrode plate, and the battery can be a solid-state battery.

[0101] It is conceivable that, in addition to the aforementioned positive electrode, the lithium-ion battery of the present invention also includes a negative electrode and a solid electrolyte layer between the positive and negative electrodes.

[0102] This invention does not strictly limit the negative electrode active material in the negative electrode sheet. It can be at least one of the negative electrode active materials commonly used in lithium-ion batteries, such as graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials (mainly including silicon suboxide and silicon-carbon negative electrodes), tin-based negative electrode materials (mainly including tin and tin alloys), and lithium metal negative electrodes.

[0103] Specifically, a battery includes a positive electrode, a negative electrode, and a solid electrolyte layer, with the solid electrolyte layer disposed between the positive electrode and the negative electrode;

[0104] Preferably, the solid electrolyte layer includes a halide solid electrolyte layer and a sulfide solid electrolyte layer stacked together.

[0105] The halide solid electrolyte layer includes a halide solid electrolyte, which accounts for 20-60% of the weight of the solid electrolyte layer.

[0106] The sulfide solid electrolyte layer includes a sulfide solid electrolyte, which accounts for 40-80% of the weight of the solid electrolyte layer; the halide solid electrolyte layer is placed on the positive electrode side and the sulfide solid electrolyte layer is placed on the negative electrode side.

[0107] Halogen solid electrolytes include: Li3YBr 5.7 F 0.3 Li7P3S 11 Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+y S 12 At least one of Li6PS5X, wherein 0 < x < 1, M includes at least one of Ge, Si, and Sn; 0 < y < 1, X includes at least one of Cl, Br, and I;

[0108] The sulfide solid electrolyte includes at least one of Li6PS5Cl, Li3MCl6, Li3Ybr6, Li3ScF6, and Li3YF6, wherein M includes at least one of Y, In, Sc, and Er.

[0109] The raw materials used in the following examples and comparative examples can all be purchased from the market.

[0110] Example 1

[0111] The preparation method of lithium-rich manganese-based cathode active material includes the following steps:

[0112] Step 1: Mix nickel sulfate solution, cobalt sulfate solution, and manganese sulfate solution thoroughly according to a Ni:Co:Mn molar ratio of 0.13:0.13:0.54. Weigh out sodium pyrophosphate, sodium tungstate, and NaOH in stoichiometric proportions (2 mol / L total ion concentration) and completely dissolve them in 5 L of deionized water to prepare a mixed alkaline solution. The molar ratio of NaOH to sodium pyrophosphate and sodium tungstate is 1:0.005:0.001. Adjust the pH to 11.5 using NH3·H2O. Then, pump the prepared salt and alkali mixtures into a reaction vessel using a peristaltic pump. The reaction vessel is stirred at 1100 rpm at 50°C. The alkali feed rate is adjusted using a three-stage speed control to maintain the pH of the solution at 11.5. After the reaction, the slurry is subjected to solid-liquid separation, centrifuged and washed with deionized water, and then dried at 100°C for 24 h to obtain the hydroxide precursor.

[0113] Step 2: The hydroxide precursor obtained in Step 1, lithium hydroxide, and lithium fluoride are mixed at a molar ratio of metal cation to Li ion of 1:1.43, wherein the molar ratio of lithium hydroxide to lithium fluoride is 143:1. After thorough mixing, the mixture is calcined in an air stream at 550°C for 5 hours, and then calcined at 880°C for 12 hours to obtain a lithium-rich manganese-based positive electrode active material.

[0114] In the lithium-rich manganese-based cathode active material of this embodiment, the measured elemental analysis showed that the mass fraction of W was 0.35 wt%, the mass fraction of P was 0.45 wt%, and the mass fraction of F was 0.1 wt%.

[0115] Example 2

[0116] The preparation method of this application is basically the same as that of Example 1, except that it also includes steps 3 and 4.

[0117] Step 3: Add 20g of lithium-rich manganese-based positive electrode active material obtained in step 2 to 70ml of ammonium metatungstate solution, wherein the concentration of ammonium metatungstate is 0.00051mol / L. After stirring thoroughly, spray dry the mixture to obtain powder. Then, sinter the spray-dried powder under air flow conditions at 600℃ for 10 hours to obtain a primary coating product with a uniform tungsten oxide coating layer on the surface.

[0118] Step 4: Mix the primary coating product obtained in Step 3 with LATP (LATP accounts for 0.4 wt% of the primary coating product), mix thoroughly using a high-speed mixer, and then calcine the mixture under air flow conditions at 300°C for 10 hours to obtain a lithium-rich manganese-based positive electrode active material with secondary coating of tungsten oxide and LATP on its surface.

[0119] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 contain W with a mass fraction of 0.35 wt%, P with a mass fraction of 0.45 wt%, and F with a mass fraction of 0.1 wt%.

[0120] Example 3

[0121] The preparation methods of this application and Example 2 are basically the same, except that the stirring speed of the reaction vessel in step 1 is changed to 1200 rpm.

[0122] Example 4

[0123] The preparation methods of this application and Example 2 are basically the same, except that the stirring speed of the reactor in step 1 is changed to 800 rpm.

[0124] Example 5

[0125] The preparation methods of this application and Example 2 are basically the same, except that the stirring speed of the reaction vessel in step 1 is changed to 900 rpm.

[0126] Example 6

[0127] The preparation methods of this application and Example 2 are basically the same, except that in step 1, the molar ratio of NaOH to sodium pyrophosphate and sodium tungstate in the mixed alkaline solution is 1:0.009:0.001.

[0128] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 contain W with a mass fraction of 0.35 wt%, P with a mass fraction of 0.8 wt%, and F with a mass fraction of 0.1 wt%.

[0129] Example 7

[0130] The preparation methods of this application and Example 2 are basically similar, except that in step 1, the molar ratio of NaOH to sodium pyrophosphate and sodium tungstate in the mixed alkaline solution is 1:0.0025:0.001.

[0131] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 contain W with a mass fraction of 0.35 wt%, P with a mass fraction of 0.2 wt%, and F with a mass fraction of 0.1 wt%.

[0132] Example 8

[0133] The preparation methods of this application and Example 2 are basically the same, except that in step 1, the molar ratio of NaOH to sodium pyrophosphate and sodium tungstate in the mixed alkaline solution is 1:0.005:0.0015.

[0134] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 have a W element mass fraction of 0.5 wt%, a P element mass fraction of 0.45 wt%, and a F element mass fraction of 0.1 wt%.

[0135] Example 9

[0136] The preparation methods of this application and Example 2 are basically the same, except that in step 1, the molar ratio of NaOH to sodium pyrophosphate and sodium tungstate in the mixed alkaline solution is 1:0.005:0.00029.

[0137] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 have a W element mass fraction of 0.1 wt%, a P element mass fraction of 0.45 wt%, and a F element mass fraction of 0.1 wt%.

[0138] Example 10

[0139] The preparation methods of this application and Example 2 are basically the same, except that in step 1, the amounts of lithium hydroxide and lithium fluoride are changed, and the molar ratio of lithium hydroxide and lithium fluoride is 286:1.

[0140] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 have a W element mass fraction of 0.35 wt%, a P element mass fraction of 0.45 wt%, and a F element mass fraction of 0.05 wt%.

[0141] Example 11

[0142] The preparation methods of this application and Example 2 are basically the same, except that in step 1, the amounts of lithium hydroxide and lithium fluoride are changed, and the molar ratio of lithium hydroxide and lithium fluoride is 36:1.

[0143] In the lithium-rich manganese-based cathode active material of this embodiment, the secondary single-crystal particles obtained in step 2 have a W element mass fraction of 0.35 wt%, a P element mass fraction of 0.45 wt%, and a F element mass fraction of 0.4 wt%.

[0144] Example 12

[0145] The preparation methods of this application and Example 2 are basically the same, except that the stirring speed of the reactor in step 1 is changed to 600 rpm.

[0146] Comparative Example 1

[0147] The difference from Example 2 is that the mixed alkaline solution in step 1 is prepared from NaOH and NH3·H2O, that is, the P-containing compound and the W-containing compound are omitted.

[0148] Comparative Example 2

[0149] The difference from Example 2 is that the mixed alkaline solution in step 1 is prepared with a W-containing compound, NaOH, and NH3·H2O, that is, the P-containing compound is omitted.

[0150] Comparative Example 3

[0151] The difference from Example 2 is that the mixed alkaline solution in step 1 is prepared by a P-containing compound and NaOH and NH3·H2O, that is, the W-containing compound is omitted.

[0152] Comparative Example 4

[0153] The difference from Example 2 is that LiF is omitted in step 2.

[0154] Comparative Example 5

[0155] The difference from Example 1 is that the mixed alkaline solution in step 1 is prepared from NaOH and NH3·H2O, that is, the P-containing compound and the W-containing compound are omitted.

[0156] Comparative Example 6

[0157] The difference from Example 1 is that the mixed alkaline solution in step 1 is prepared with a W-containing compound, NaOH, and NH3·H2O, that is, the P-containing compound is omitted.

[0158] Comparative Example 7

[0159] The difference from Example 1 is that the mixed alkaline solution in step 1 is prepared by a P-containing compound and NaOH and NH3·H2O, that is, the W-containing compound is omitted.

[0160] Comparative Example 8

[0161] The difference from Example 2 is that the mixed alkaline solution in step 1 is prepared from sodium pyrophosphate, sodium tungstate, Na2CO3, and NH3·H2O, wherein the molar ratio of Na2CO3, NH3·H2O to sodium pyrophosphate and sodium tungstate is 1:0.0025:0.0005.

[0162] Test Example 1

[0163] Particle size testing: The lithium-rich manganese-based cathode active material samples from each example and comparative example were dispersed in a solvent, and the particle size distribution data were tested using a laser particle size analyzer to obtain the average particle size, Dv10, Dv50, and Dv90. The particle size distribution width (Span) value is (Dv90-Dv10) / Dv50.

[0164] Element content testing: The content of each element was determined by ICP-MS analysis.

[0165] Powder resistivity test: The positive electrode powder is placed in a mold and pressurized to form a dense sample block. Electrodes are connected to both ends of the sample block, a known voltage is applied, the current is measured, and the resistivity is calculated using a formula based on the measured resistance value.

[0166] Compaction density test: The lithium-rich manganese-based positive electrode active materials of each embodiment and comparative example were placed into the compaction chamber of the compactor and compressed under a pressure of 5 tons. The compaction density was calculated based on the material mass and the volume after compaction.

[0167] First coating thickness test: The thickness of the first coating in the cross-section of each lithium-rich manganese-based cathode active material was measured by transmission electron microscopy.

[0168] Coverage test of the second coating layer on lithium-rich manganese-based cathode material: The area of ​​LATP on the surface of each lithium-rich manganese-based cathode active material and the area of ​​the lithium-rich manganese-based cathode material were observed and measured by scanning electron microscopy. Coverage rate = area occupied by LATP / area of ​​lithium-rich manganese-based cathode material. The average value of multiple test groups was taken as the coverage rate of the second coating layer.

[0169] Table 1

[0170]

[0171] Table 2

[0172]

[0173] The lithium-rich manganese-based positive electrode active materials obtained in Example 2 and Comparative Examples 1, 2, and 3 were analyzed using scanning electron microscopy, and their scanning electron micrographs were obtained. Figure 1 This is a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material from Example 2. Figure 1 It can be seen that the lithium-rich manganese-based cathode active material prepared in the embodiments of the present invention has a morphological structure of a single-crystal-like secondary particle composed of no more than 10 primary particles. The span is 1.01, and the BET is 2.8856m. 2 / g, and the material is doped with W, P and F elements, which hinder the excessive growth of grains, resulting in a reduction in particle size and the formation of more uniform nano- or submicron-sized particles.

[0174] Figure 2 This is an elemental distribution diagram of the grain cross-section of the lithium-rich manganese-based cathode active material in Example 2. Figure 3 This is an EDS line scan diagram of the grain cross-section of the lithium-rich manganese-based cathode active material in Example 2. Figure 4 This is an EDS line scan image of the grain profile of the lithium-rich manganese-based cathode active material in Example 2. Figure 4 In accordance with Figure 3 The data results obtained by line scanning of the line data in the middle, from Figure 4 As can be seen, the content of phosphorus (P) is higher on the material surface, and there is some segregation at the grain boundaries, mainly coexisting in two ways: bulk doping and grain boundary segregation. The elemental distribution diagram of the grain profile shows that inside the material, the boundaries between primary particles are very dense, with virtually no obvious pores. On the material surface, the primary particles are also tightly bound together, with no obvious pores or significant accumulation of coatings.

[0175] Figure 5 The image shows a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material in Comparative Example 1. The hydroxide precursor in Comparative Example 1 was not doped with any elements, resulting in poor uniformity in the primary particle size of the final material. The particles varied in size and easily agglomerated, forming aggregates with a span value of 1.95. This leads to uneven capacity utilization, with larger particles exhibiting longer lithium-ion diffusion paths and increased polarization, while smaller particles have larger specific surface areas, resulting in more side reactions. Consequently, the overall battery capacity cannot be fully utilized, leading to a decrease in energy density.

[0176] Figure 6 The image shows a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material in Comparative Example 2. The hydroxide precursor only added W element, and the size uniformity of the primary particles was better than that of Comparative Example 1 without added dopants. However, the morphology of the primary particles still showed easy agglomeration, and the morphology showed primary particle agglomerates. There were large pores between the primary particles, and the fluidity and processing performance were poor during the preparation process.

[0177] Figure 7 The image shows a scanning electron microscope (SEM) image of the lithium-rich manganese-based cathode active material in Comparative Example 3. Compared to Example 1, only P element was added to the hydroxide precursor. Since P element segregates at the grain boundaries, it hinders the excessive growth of grains and leads to a reduction in the size of primary particles. However, the small size of primary particles means that the surface energy is large, and agglomeration is very easy to occur, which increases the Dv50 and span values ​​of secondary single-crystal particles, which is not conducive to the processing of materials and the utilization of capacity.

[0178] The lithium-rich manganese-based cathode active material of the embodiment was tested by spherical aberration electron microscopy, which showed that W was doped at the transition metal sites and F was doped at the O sites.

[0179] In each embodiment, doping with W, P, and F elements makes it easier to control the ratio of the average particle size of secondary single-crystal particles to the average particle size of primary particles within the range of (2.5~10):1, resulting in a smaller particle size distribution width (span value). However, Comparative Examples 1, 2, and 3, which have a coating layer, show larger average particle size and Dv50 particle size, as well as a larger span value, compared to Example 2 with a coating layer. This lack of the synergistic effect of the three elements leads to uneven capacity utilization, with larger particles resulting in longer lithium-ion diffusion paths and insufficient overall battery capacity. Similarly, for comparisons without a coating layer, Comparative Examples 5, 6, and 7, compared to Example 1, lack the synergistic effect of the three elements, resulting in larger average particle size and Dv50 particle size, and a larger span value for the secondary single-crystal particles.

[0180] In Comparative Example 4, no lithium fluoride was added (i.e., no F element was added). The lack of the fluxing effect of lithium fluoride would reduce the average particle size of the primary particles.

[0181] The polycrystalline lithium-rich manganese-based cathode active material prepared in Comparative Example 8 has an average particle size ratio of 70:1 between secondary single-crystal particles and primary particles. Subsequent battery performance tests show that this structure cannot fully utilize its capacity.

[0182] The lithium-rich manganese-based positive electrode active materials of the above embodiments and comparative examples were used to fabricate solid-state batteries. The structure of the all-solid-state battery is as follows: Figure 8 As shown, it sequentially includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The positive electrode layer comprises the aforementioned lithium-rich manganese-based positive electrode active material, a halide solid electrolyte, and VGCF; the solid electrolyte layer comprises a halide solid electrolyte layer and a sulfide solid electrolyte layer; and the negative electrode layer comprises indium metal and lithium metal.

[0183] The positive electrode layer contains 80% lithium-rich manganese-based positive electrode active material by weight, and 20% halide solid electrolyte by weight, specifically Li3YBr. 5.7 F 0.3 .

[0184] The solid electrolyte layer contains a halide solid electrolyte layer accounting for 40% of the weight of the solid electrolyte layer, and a sulfide solid electrolyte layer accounting for 60% of the weight of the solid electrolyte layer. The halide solid electrolyte layer is placed on the positive electrode side, and the sulfide solid electrolyte layer is placed on the negative electrode side. The sulfide solid electrolyte is Li6PS5Cl.

[0185] The negative electrode layer contains indium metal and lithium metal, with the indium metal layer having a thickness of 100µm and the lithium metal layer having a thickness of 100µm, and the indium metal layer being placed on one side of the solid electrolyte layer.

[0186] The specific fabrication steps of all-solid-state batteries include:

[0187] 1) Positive electrode treatment: This positive electrode material is reacted with a halide solid electrolyte (Li3YBr). 5.7 F 0.3 The mixture and the conductive agent (VGCF) were dry-mixed under inert conditions (humidity <1ppm) to avoid hydrolysis of halides; the mixture was then manually ground for 1 hour.

[0188] 2) Negative electrode processing: The lithium and indium sheets are pressed into sheets with a thickness of 100μm using a roller press, and then sliced ​​into sheets using a slicing machine for later use;

[0189] 3) Assembling the molded battery: First, place the ground positive electrode and halide mixture into the molded battery sleeve, and press it into sheets using a tablet press with a pressure of 2 tons. Then, place the halide solid electrolyte into the molded battery sleeve, on top of the positive electrode and halide mixture sheets. Press the sleeve into sheets using a tablet press with a pressure of 2 tons. Next, add the sulfide electrolyte (Li6PS5Cl) into the molded battery sleeve, on top of the halide sheets. Press the sleeve into the tablet press with a pressure of 2 tons to press the sulfide electrolyte into sheets. Then, place the indium metal slices into the sleeve, on top of the sulfide sheets. Finally, place the lithium metal slices into the sleeve. Place the molded battery sleeve into a pressure-controlled device and apply pressure using a torque wrench. At this point, the molded battery assembly is complete.

[0190] Test Example 2

[0191] Charge / discharge specific capacity and initial coulombic efficiency: At 25℃, the battery is charged to 4.2V at a constant current of 0.1C (1C=250mAh / g), and then charged at a constant voltage with a cutoff current of 0.025C. The charging capacity at this point is recorded as the battery's initial charge specific capacity. Subsequently, it is discharged to 1.9V at a constant current of 0.1C, and the discharge capacity at this point is recorded as the initial discharge specific capacity. The initial discharge specific capacity divided by the initial charge specific capacity is the initial coulombic efficiency.

[0192] Capacity retention test after 100 cycles: At 25℃, the capacitor was charged at a constant current rate of 1C to 4.2V, then charged at a constant voltage rate of 0.025C to 4.2V, and then discharged at a discharge rate of 1C to 1.9V. This charge-discharge cycle was repeated 100 times. The discharge capacity Q1 at the first cycle and the discharge capacity Q100 at the 100th cycle were measured. Capacity retention rate Q = Q100 / Q1 × 100%.

[0193] The test results for each embodiment and comparative example are detailed in Table 3.

[0194] Table 3

[0195]

[0196] Based on the data in Table 3, with the coating layer, Examples 2-12, containing W, P, and F dopants, exhibited better cycle stability and discharge specific capacity compared to Comparative Examples 1-4, significantly improving battery performance. Without the coating layer, Example 1, containing W, P, and F dopants, showed better cycle stability and discharge specific capacity compared to Comparative Examples 5-7. In Comparative Example 8, the ratio of the average particle size of secondary particles to the average particle size of primary particles was as high as 70:1, indicating excessive grain boundaries in the material, resulting in poor cycle stability and an inability to fully utilize its capacity.

[0197] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A lithium-rich manganese-based cathode active material, characterized in that, It includes secondary-like single-crystal particles formed from primary particles, wherein the ratio of the average particle size of the secondary-like single-crystal particles to the average particle size of the primary particles is (2.5~10):1; The lithium-rich manganese-based positive electrode active material contains W, P and F elements; The secondary single-crystal particles refer to those formed by the aggregation of 2 to 10 primary particles.

2. The lithium-rich manganese-based positive electrode active material according to claim 1, characterized in that, The ratio of the particle size Dv50 of the secondary single crystal particles to the average particle size of the secondary single crystal particles is (1.1~1.5):1; And / or, the particle size distribution width (Span) of the secondary single-crystal particles is 0.8~1.5; The span value is (Dv90-Dv10) / Dv50.

3. The lithium-rich manganese-based positive electrode active material according to claim 2, characterized in that, The average particle size of the primary particles is 200 nm to 500 nm; And / or, the average particle size of the secondary single-crystal particles is 1~5μm; And / or, the particle size Dv50 of the secondary single-crystal particles is 1~8μm; And / or, the particle size Dv10 of the secondary single-crystal particles is 0.5~2.5μm; And / or, the particle size Dv90 of the secondary single-crystal particles is 1.8~14μm.

4. The lithium-rich manganese-based positive electrode active material according to any one of claims 1-3, characterized in that, The primary particle comprises a bulk matrix and a surface matrix, the surface matrix being located on at least a portion of the outer surface of the bulk matrix, the center of the primary particle being located in the bulk matrix, and the surface matrix of the primary particle containing the element P; Preferably, the mass content of P element in the surface matrix of the primary particles is higher than the mass content of P element in the bulk matrix.

5. The lithium-rich manganese-based positive electrode active material according to claim 4, characterized in that, Both the bulk matrix and the surface matrix of the primary particles contain W, F, and P elements; Preferably, the F element is located at the lattice oxygen site of the primary particle; Preferably, the W element is located at a lattice transition metal site of the primary particle; The transition metal includes at least one of Ni, Co, and Mn.

6. The lithium-rich manganese-based positive electrode active material according to any one of claims 1-3, characterized in that, The outer surface of the secondary single-crystal particles is covered with a first coating layer and a second coating layer, wherein the second coating layer partially covers the surface of the first coating layer. The first covering layer includes W elements; Preferably, the first coating layer comprises at least one of tungsten oxide and lithium tungstate, and the second coating layer comprises lithium aluminum titanium phosphate; Preferably, the thickness of the first coating layer is 5-30 nm; Preferably, the coverage of the second coating layer is 10-30%.

7. The lithium-rich manganese-based positive electrode active material according to any one of claims 1-3, characterized in that, The W element has a mass fraction of 0.01–0.5 wt% in the secondary single-crystal particles; And / or, the P element has a mass fraction of 0.02 to 0.8 wt% in the secondary single-crystal particles; And / or, the F element has a mass fraction of 0.005–0.4 wt% in the secondary single-crystal particles; and / or, the general chemical formula of the lithium-rich manganese-based cathode active material is: aLi2MnO3·(1-a)LiNi x Co y Mn z W d P b A k O e F c , where 0 < a < 1, 0 < x < 1, 0 ≤ y < 1, 0 < z < 1, 0 < b < 1, 0 < c < 2, 0 < d < 1, 0 < e < 2, A includes at least one of Al, Mg, Ti, Zr, Sr, B, Nb, Tb, Y, La, and 0 ≤ k < 1.

8. The lithium-rich manganese-based positive electrode active material according to any one of claims 1-3, characterized in that, The specific surface area of ​​the lithium-rich manganese-based cathode active material is 2.2~3.3 m². 2 / g; And / or, the compaction density of the lithium-rich manganese-based cathode active material is 2.7~3.2 g / cc; And / or, the powder conductivity of the lithium-rich manganese-based positive electrode active material is 6.23E. -07 ~5.69E -05 S / cm.

9. A positive electrode plate, characterized in that, The positive electrode sheet comprises the lithium-rich manganese-based positive electrode active material according to any one of claims 1-7.

10. A battery, characterized in that, The battery includes the positive electrode, the negative electrode, and the solid electrolyte layer as described in claim 9, wherein the solid electrolyte layer is disposed between the positive electrode and the negative electrode. Preferably, the solid electrolyte layer comprises a halide solid electrolyte layer and a sulfide solid electrolyte layer stacked together; Preferably, the halide solid electrolyte layer is placed on one side of the positive electrode, and the sulfide solid electrolyte layer is placed on one side of the negative electrode. The halide solid electrolyte layer includes a halide solid electrolyte, which accounts for 20-60% of the weight of the solid electrolyte layer. The sulfide solid electrolyte layer includes a sulfide solid electrolyte, and the sulfide solid electrolyte accounts for 40-80% of the weight of the solid electrolyte layer. The halide solid electrolyte includes: Li3YBr 5.7 F 0.3 Li7P3S 11 Li 4-x Ge 1-x P x S4, Li 11-y M 2-y P 1+y S 12 At least one of Li6PS5X, wherein 0 < x < 1, M includes at least one of Ge, Si, and Sn; 0 < y < 1, X includes at least one of Cl, Br, and I; The sulfide solid electrolyte includes at least one of Li6PS5Cl, Li3MCl6, Li3Ybr6, Li3ScF6, and Li3YF6, wherein M includes at least one of Y, In, Sc, and Er.

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