Lithium-rich manganese-based layered positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device

Abstract

This invention relates to the field of lithium-ion battery technology, specifically to a lithium-rich manganese-based substrate cathode material and its preparation method, cathode sheet, lithium-ion battery, and electrical device. The lithium-rich manganese-based substrate cathode material includes a first phase Li₂Mn with space group C² / m. 1‑ a A a O3 and the second phase LiMn with space group R-3m b X c A a O2, the general formula of lithium-rich manganese-based substrate cathode materials is nLi2Mn 1‑a A a O3·(1-n)LiMn b X c A a O2; the absolute value of the lattice microstrain of the first phase, |ST1|, is ≤0.25%, and the absolute value of the lattice microstrain of the second phase, |ST2|, is ≤0.20%; the absolute value of the lattice microstrain ST of the lithium-rich manganese-based substrate cathode material, |ST|, is ≤0.20%. The lithium-rich manganese-based substrate cathode material provided by this invention has high first-cycle coulombic efficiency and high capacity retention.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to lithium-rich manganese-based substrate cathode materials and their preparation methods, cathode sheets, lithium-ion batteries, and electrical devices. Background Technology

[0002] The rapid development of new energy vehicles has placed higher demands on the energy density of lithium-ion batteries. Exploring a low-cost, high-energy-density cathode material to meet the needs of power batteries and solve the "range anxiety" problem is one of the important tasks at present. Lithium-rich manganese-based layered cathode materials have attracted widespread attention due to their high specific capacity (over 250 mAh / g) and relatively high operating voltage.

[0003] However, the structural characteristics and unique capacity generation mechanism of lithium-rich manganese-based substrate materials differ significantly from those of traditional LiCoO2 or ternary materials. While the redox reaction of oxygen anions in lithium-rich manganese-based substrate cathode materials provides high specific capacity, it also easily leads to the extraction of some oxygen ions from the crystal lattice, resulting in irreversible capacity. This results in a low initial coulombic efficiency, and the oxygen vacancies left after extraction cause transition metal ions to migrate, leading to irreversible phase transitions and voltage decay. This results in problems such as irreversible oxygen precipitation, low initial coulombic efficiency, and severe capacity and voltage decay, hindering the industrial application of this material in lithium-ion batteries. The initial material structure is extremely complex, generally considered to be a fusion of the Li2MnO3 structure and the traditional LiMO2 (M = Ni, Co, Mn, etc.) structure at the atomic scale. The arrangement of local structures has a fundamental impact on electrochemical reactions, especially the redox reaction of oxygen anions.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a lithium-rich manganese-based substrate cathode material, which to some extent addresses the problems of low initial coulombic efficiency and severe capacity or voltage decay inherent in conventional lithium-rich manganese-based substrate cathode materials. The lithium-rich manganese-based substrate cathode material provided by this invention exhibits high initial coulombic efficiency and high capacity retention.

[0006] The second objective of this invention is to provide a method for preparing a lithium-rich manganese-based substrate cathode material.

[0007] The third objective of this invention is to provide a positive electrode sheet.

[0008] The fourth objective of this invention is to provide a lithium-ion battery.

[0009] The fifth objective of this invention is to provide an electrical appliance.

[0010] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0011] The present invention provides a lithium-rich manganese-based layered cathode material, which includes a first phase Li2Mn 1-a A a O3 with a space group of C2 / m and a second phase LiMn b X c A a O2 with a space group of R-3m. The general formula of the lithium-rich manganese-based layered cathode material is nLi2Mn 1-a A a O3·(1-n)LiMn b X c A a O2;

[0012] where 0.2 ≤ n ≤ 0.6, 0 < a ≤ 0.05, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 1, and a + b + c = 1; X includes at least one of Ni, Co, and Al elements, and A includes at least one of Ti, Zr, Ce, Mo, Nb, Ta, and W elements;

[0013] The absolute value of the lattice microstrain of the first phase |ST1| ≤ 0.25%, and the absolute value of the lattice microstrain of the second phase |ST2| ≤ 0.20%; the lattice microstrain ST of the lithium-rich manganese-based layered cathode material is ST = n·ST1 + exp(b)·(1 - n)·ST2, and the absolute value of ST |ST| ≤ 0.20%.

[0014] The present invention also provides a preparation method of a lithium-rich manganese-based layered cathode material, including the following steps:

[0015] A mixed material containing Li source, Mn source, X source, and A source is calcined in two stages to obtain a calcined material; the calcined material is calcined a second time to obtain the lithium-rich manganese-based layered cathode material;

[0016] The X source includes a compound containing X, where X includes at least one of Ni, Co, and Al elements;

[0017] The A source includes a compound containing A, where A includes at least one of Ti, Zr, Ce, Mo, Nb, Ta, and W elements.

[0018] The present invention further provides a positive electrode sheet, including the above-mentioned lithium-rich manganese-based layered cathode material.

[0019] The present invention also provides a lithium-ion battery, including the above-mentioned positive electrode sheet.

[0020] The present invention also provides an electrical device, including the aforementioned lithium-ion battery.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The lithium-rich manganese-based substrate cathode material provided by the present invention, by optimizing the composition of the cathode material, constructs a first phase Li2Mn with a space group of C2 / m. 1-a A a O3 and the second phase LiMn with space group R-3m b X c A a By controlling the ratio and composition of the first and second phases, as well as the lattice microstrain of the lithium-rich manganese-based substrate cathode material, the electronic activity of oxygen anions and the Li2Mn content of the two-phase low-strain symbiotic structure can be enhanced. 1-a A a The lithium-ion insertion / extraction capability of the O3 phase enhances the reversibility and recoverability of anion oxidation and reduction reactions, thereby improving the first-cycle coulombic efficiency of the cathode material and increasing the capacity and voltage retention rate during long-cycle operation.

[0023] (2) The method for preparing lithium-rich manganese-based substrate cathode material provided by the present invention, by optimizing the synthesis process, such as subjecting the calcined material to a second calcination, can regulate the Li2Mn content. 1-a A a O3 phase, LiMn b X c A a The O2 phase and the lattice micro-strain of the lithium-rich manganese-based substrate cathode material improve the first-cycle coulombic efficiency of the lithium-rich manganese-based substrate cathode material and suppress capacity and voltage decay during cycling. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 The XRD pattern of the lithium-rich manganese-based substrate cathode material provided in Embodiment 1 of the present invention;

[0026] Figure 2 The Williamson-Hall spectra of the two phases in the lithium-rich manganese-based substrate cathode material provided in Example 1 of this invention;

[0027] Figure 3SEM image of the lithium-rich manganese-based layered cathode material provided in Embodiment 1 of the present invention. Detailed implementation manners

[0028] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and specific implementation manners. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0029] In the first aspect, the present invention provides a lithium-rich manganese-based layered cathode material, which includes a first phase Li2Mn 1-a A a O3 with a space group of C2 / m and a second phase LiMn b X c A a O2 with a space group of R-3m. The two-phase composite of the first phase Li2Mn 1-a A a O3 and the second phase LiMn b X c A a O2 is a low-strain dispersion co-existing structure.

[0030] The general formula of the lithium-rich manganese-based layered cathode material is nLi2Mn 1-a A a O3·(1 - n)LiMn b X c A a [[ID=4l]]O2. Where 0.2 ≤ n ≤ 0.6, 0 < a ≤ 0.05, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 1, and a + b + c = 1.

[0031] The above general formula nLi2Mn 1-a [[ID=B]]A a O3·(1 - n)LiMn b X c A aIn O2, n includes, but is not limited to, any one of the values ​​of 0.2, 0.3, 0.4, 0.5, and 0.6, or any range between any two; a includes, but is not limited to, any one of the values ​​of 0.001, 0.003, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, and 0.05, or any range between any two; b includes, but is not limited to, any one of the values ​​of 0, 0.01, 0.03, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, and 0.5, or any range between any two; c includes, but is not limited to, any one of the values ​​of 0, 0.01, 0.03, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0, or any range between any two.

[0032] The above general formula nLi2Mn 1-a A a O3·(1-n)LiMn b X c A a In O2, X includes at least one of Ni, Co, and Al; A is a 3d, 4d, or 5d transition metal element, the valence state of A is ≥ +4, and A in the AO6 octahedral coordination field... m+ Ionic radius It includes at least one of the elements Ti, Zr, Ce, Mo, Nb, Ta, and W.

[0033] The first phase Li2Mn 1-a A a The absolute value of the lattice microstrain of O3, |ST1|, is ≤0.25%, including but not limited to point values ​​of any one of 0.25%, 0.20%, 0.15%, 0.1%, 0.05%, and 0.01%, or range values ​​between any two.

[0034] The second phase LiMn b X c A a The absolute value of the lattice microstrain of O2, |ST2|, is ≤0.20%; including but not limited to point values ​​or ranges between any one of 0.20%, 0.18%, 0.15%, 0.13%, 0.1%, 0.08%, 0.05%, 0.03%, and 0.01%.

[0035] The lattice microstrain ST of the lithium-rich manganese-based substrate cathode material is ST = n·ST1 + exp(b)·(1-n)·ST2, and the absolute value of the lattice microstrain ST of the lithium-rich manganese-based substrate cathode material, |ST|, is ≤0.20%, wherein |ST| includes, but is not limited to, any one of 0.20%, 0.18%, 0.15%, 0.13%, 0.1%, 0.08%, 0.05%, 0.03%, 0.01%, or a range between any two.

[0036] The electrochemical activity of oxygen anions in lithium-rich manganese-based substrate cathode materials is closely related to the localized structure of the first phase (C2 / m space group) and the second phase (R-3m space group) in the cathode material composition. This invention optimizes the composition of the cathode material to construct Li2Mn... 1-a A a O3 and LiMn b X c A a The O2 two-phase low-strain dispersed coexistence structure modulates the lattice microstrain of the first phase, second phase, and lithium-rich manganese-based substrate cathode material. The lattice microstrain refers to the ratio (Δd / d*100%) of the change in lattice spacing due to tensile or compressive stress to the intrinsic lattice spacing d. Density functional theory calculations show that the stress state affects the density of states of lattice oxygen in the lithium-rich cathode material, resulting in different lattice oxygen activities. This can enhance the electronic activity of oxygen anions and the activity of Li2Mn. 1-a A a The lithium-ion insertion / extraction capability of the O3 phase enhances the reversibility and recoverability of anion oxidation and reduction reactions, thereby improving the first-cycle coulombic efficiency of the cathode material and the retention rate of capacity and voltage during long-cycle operation.

[0037] In some embodiments, the median particle size D50 of the lithium-rich manganese-based basal cathode material is 2 to 15 μm; including but not limited to point values ​​or ranges between any one of 2 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, 12 μm, 14 μm, and 15 μm.

[0038] In some embodiments, the lithium-rich manganese-based substrate cathode material comprises secondary particles formed by the agglomeration of primary particles. The median particle size D50 of the primary particles is 20–500 nm, including but not limited to point values ​​or ranges between any one of 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, and 500 nm. The primary particles comprise a first phase Li₂Mn with space group C² / m. 1-a A aO3 and the second phase LiMn with space group R-3m b X c A a O2.

[0039] In some embodiments, the specific surface area of ​​the lithium-rich manganese-based substrate cathode material is 0.3–6.0 m². 2 / g, including but not limited to 0.3m 2 / g, 0.5m 2 / g, 0.8m 2 / g, 1.0m 2 / g, 1.5m 2 / g, 2.0m 2 / g, 2.5m 2 / g, 3.0m 2 / g, 3.5m 2 / g, 4.0m 2 / g, 4.5m 2 / g, 5.0m 2 / g, 5.5m 2 / g, 6.0m 2 The point value of any one of / g or the range value between any two.

[0040] By using the particle size and specific surface area within the above range, sufficient contact between the electrode and the electrolyte can be ensured.

[0041] In some embodiments, the LiOH content in the lithium-rich manganese-based substrate cathode material is ≤2500ppm, including but not limited to any one of 2500ppm, 2300ppm, 2000ppm, 1500ppm, 1000ppm, 500ppm, 300ppm, and 100ppm, or a range between any two.

[0042] In some embodiments, the Li2CO3 content in the lithium-rich manganese-based substrate cathode material is ≤2500ppm, including but not limited to any one of 2500ppm, 2300ppm, 2000ppm, 1500ppm, 1000ppm, 500ppm, 300ppm, and 100ppm, or a range between any two.

[0043] The lithium-rich manganese-based cathode material with a specific general formula provided by this invention has a low residual alkali content, which is beneficial to improving the first coulombic efficiency of the cathode material and reducing gas production.

[0044] In some embodiments, the lithium-rich manganese-based substrate cathode material is mainly prepared by a mixture containing Li, Mn, X, and A sources through a two-stage calcination and a second calcination. The two-stage calcination refers to a first calcination at a low temperature followed by a second calcination at a high temperature, collectively referred to as the first calcination. The second calcination refers to the second calcination. More preferably, the temperature of the second calcination is 500–900°C, including but not limited to any one of 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, and 900°C, or a range between any two; the holding time of the second calcination is 2–10 hours, including but not limited to any one of 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, and 10 hours, or a range between any two. This method can further reduce the residual alkali content.

[0045] Secondary calcination helps control the Li2Mn content. 1-a A a The absolute value of the lattice microstrain of O3, |ST1|, is ≤0.25%, and that of LiMn is also present. b X c A a The absolute value of the lattice microstrain of O2, |ST2|, is ≤0.20%, and the absolute value of the lattice microstrain of lithium-rich manganese-based substrate cathode material, |ST|, is ≤0.20%.

[0046] Secondly, the present invention provides a method for preparing the above-mentioned lithium-rich manganese-based substrate cathode material, comprising the following steps:

[0047] A mixture containing Li, Mn, X, and A sources is calcined in two stages to obtain calcined feedstock. The two-stage calcination refers to a continuous process involving first low-temperature calcination followed by high-temperature calcination.

[0048] The calcined material obtained in the above steps is then subjected to a second calcination, and after cooling, the lithium-rich manganese-based basal cathode material is obtained.

[0049] The X source includes a compound containing X, wherein X includes at least one of the elements Ni, Co, and Al.

[0050] The A source includes compounds containing A, wherein A includes at least one of the elements Ti, Zr, Ce, Mo, Nb, Ta, and W.

[0051] The method for preparing lithium-rich manganese-based substrate cathode material provided by this invention optimizes the synthesis process, especially by subjecting the calcined material to a second calcination, thereby controlling the Li2Mn content. 1-a A a O3 phase, LiMn b X c A aThe O2 phase and the microscopic strain of the lattice of the lithium-rich manganese-based substrate cathode material can improve the initial coulombic efficiency of the lithium-rich manganese-based substrate cathode material and suppress capacity and voltage decay during cycling.

[0052] Specifically, the second calcination can achieve inter-atomic diffusion at a lower temperature, thereby reducing the lattice strain of the first phase, the second phase, and the lithium-rich manganese-based substrate cathode material.

[0053] In some embodiments, the two-stage calcination is the first calcination, more specifically, a step-by-step calcination, which includes the following steps: first, holding at 300–600℃ for 2–8 hours (referred to as first-stage calcination), and then holding at 750–950℃ for 12–30 hours (referred to as second-stage calcination). The first-stage calcination mainly involves the dehydration and preliminary decomposition of the mixture; the second-stage calcination involves the solid-state reaction of the compounds of Li, Mn, X, and A, resulting in a well-crystallized two-phase composite material.

[0054] The calcination temperature for one stage includes, but is not limited to, any one of 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃ or any range between two of them; the holding time for one stage of calcination includes, but is not limited to, any one of 2h, 3h, 4h, 5h, 6h, 7h, 8h or any range between two of them.

[0055] The temperature for the second-stage calcination includes, but is not limited to, any one of 750℃, 800℃, 850℃, 900℃, and 950℃, or any range between two of these values. The holding time for the second-stage calcination includes, but is not limited to, any one of 12h, 15h, 18h, 20h, 22h, 25h, 28h, and 30h, or any range between two of these values.

[0056] In some embodiments, the second calcination (i.e., the second calcination) includes the following step: holding at 500–900°C for 2–10 hours. The temperature of the second calcination includes, but is not limited to, any one of 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, and 900°C, or a range between any two. The holding time of the second calcination includes, but is not limited to, any one of 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, and 10 hours, or a range between any two.

[0057] In some embodiments, the heating rates of the two-stage calcination and / or the second calcination are each independently 1 to 10 °C / min, including but not limited to any one of 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min, and 10 °C / min, or any range between the two.

[0058] In some embodiments, the atmosphere for the second calcination includes an oxygen-containing atmosphere. More preferably, the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.

[0059] In some embodiments, the atmosphere for the two-stage calcination includes an oxygen-containing atmosphere. More preferably, the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.

[0060] In some embodiments, a step of uniformly dispersing the calcined material is included before the second calcination. More preferably, the uniform dispersion is carried out in a mixing device to improve the dispersion uniformity of lithium elements in the calcined material, avoid lithium segregation, and thus control the lattice micro-strain of the cathode material. The mixing device can be any conventional equipment with mixing and dispersing properties, such as a high-speed mixer, a double-cone mixer, a plow mixer, and a planetary ball mill, but is not limited to these.

[0061] In some embodiments, the Li source includes a lithium-containing compound. More preferably, the lithium-containing compound includes one or more of LiOH, Li₂CO₃, Li₂SO₄, LiCl, and LiNO₃.

[0062] In some embodiments, the Mn source includes a manganese-containing compound. More preferably, the manganese-containing compound includes one or more of MnO, MnO2, Mn3O4, MnCO3, and MnSO4.

[0063] In some embodiments, the compound containing X includes one or more of the following: oxides, hydroxides, carbonates, and sulfates containing X. X includes at least one of the elements Ni, Co, and Al.

[0064] In some embodiments, the A-containing compound includes one or more of A-containing oxides, hydroxides, and carbonates. A includes at least one of the elements Ti, Zr, Ce, Mo, Nb, Ta, and W.

[0065] In some embodiments, the preparation method of a mixture containing Li, Mn, X, and A sources includes: mixing the Li, Mn, X, and A sources with a solvent at a certain molar ratio to obtain a slurry; pumping the slurry into a spray drying device for spray drying, so that the solvent in the slurry evaporates, resulting in a powder with a uniform mixture of multiple metal elements, which is the mixture containing Li, Mn, X, and A sources. This method is beneficial for improving the uniformity of elemental distribution in the mixture and the final product.

[0066] The solvent used can be any conventional solvent, including water and non-aqueous solvents. The amount of solvent used can also be conventional.

[0067] More preferably, the solvent includes one or more of deionized water, ethanol, and methanol.

[0068] More preferably, the ratio of the mass of the solvent to the total mass of all other raw materials is 0.5 to 2:1, including but not limited to a point value of any one of 0.5:1, 1:1, 1.5:1, 2:1, or a range between any two.

[0069] More preferably, the mixing is carried out in a grinding apparatus, such as a sand mill, but not limited thereto.

[0070] More preferably, the slurry is pumped into the spray drying equipment by a peristaltic pump at a rate of 0.2 to 5 L / min, including but not limited to any one of 0.2 L / min, 0.5 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, and 5 L / min, or a range between any two.

[0071] More preferably, the inlet air temperature of the spray dryer is 120–300°C, including but not limited to any one of 120°C, 150°C, 180°C, 200°C, 250°C, 280°C, and 300°C, or a range between any two; the outlet air temperature of the spray dryer is 80–250°C, including but not limited to any one of 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 230°C, and 250°C, or a range between any two; and the carrier gas rate of the spray dryer is 10–200 L / min, including but not limited to any one of 10 L / min, 30 L / min, 50 L / min, 100 L / min, 120 L / min, 140 L / min, 160 L / min, 180 L / min, and 200 L / min, or a range between any two.

[0072] In some embodiments, the calcined material is cooled after the second calcination, and then crushed and sieved to obtain the lithium-rich manganese-based layered cathode material.

[0073] In some embodiments, in the mixed material containing a Li source, a Mn source, an X source, and an A source, the molar ratios of the lithium element in the Li source, the manganese element in the Mn source, the X element in the X source, and the A element in the A source satisfy the general formula nLi₂Mn 1-a A a O₃·(1 - n)LiMn b X c A a O₂, that is, the ingredients are proportioned according to the ratios of the elements in this general formula. For example, the molar ratios of the lithium element in the Li source, the manganese element in the Mn source, the X element in the X source, and the A element in the A source are n + 1 : n + b - na - nb : c - nc : a. It can be understood that any element in this molar ratio can be appropriately in excess. Among them, 0.2 ≤ n ≤ 0.6, 0 < a ≤ 0.05, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 1, and a + b + c = 1.

[0074] In a third aspect, the present invention provides a positive electrode sheet including the above-mentioned lithium-rich manganese-based layered cathode material.

[0075] In some embodiments, the positive electrode sheet further includes a conductive agent, a binder, and a current collector. The conductive agent can be any conventional conductive agent, such as carbon black, conductive graphite, carbon fiber, and carbon nanotubes, etc., but not limited thereto. The binder can be any conventional binder, such as polyvinylidene fluoride, but not limited thereto.

[0076] In a fourth aspect, the present invention provides a lithium-ion battery including the above-mentioned positive electrode sheet.

[0077] It can be understood that the lithium-ion battery further includes a negative electrode sheet, an electrolyte, and a separator. Among them, the negative electrode sheet includes a lithium metal sheet. The electrolyte is mainly composed of an organic solvent and an electrolyte lithium salt, and optionally further includes additives.

[0078] In a fifth aspect, the present invention provides an electrical device including the above-mentioned lithium-ion battery.

[0079] Among them, the electrical device includes any conventional device using a lithium-ion battery, such as an electric vehicle, an electric tool, a mobile power supply, a computer, a smart home product, an energy storage device, etc., but not limited thereto.

[0080] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0081] Example 1

[0082] The method for preparing lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0083] (1) Weigh 461.8g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 462.5g of manganese dioxide MnO2, 98.9g of cobalt oxide CoO, 97.6g of nickel oxide NiO and 9.3g of tungsten oxide WO3, add each raw material to a sand mill, add 1000mL of anhydrous ethanol, mix evenly and obtain a slurry.

[0084] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 250℃, the outlet air temperature is 120℃, and the carrier gas rate is 50L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0085] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e. two-stage calcination). First, it is calcined at 500℃ for 4 hours with a heating rate of 3℃ / min. Then, it is heated to 850℃ for 20 hours with a heating rate of 3℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0086] (4) The calcined material obtained in step (3) is mixed evenly (i.e., evenly dispersed) in a high-speed mixer, and then calcined a second time in an air atmosphere furnace (i.e., second calcination). The calcination temperature is 700℃, the calcination time is 5h, and the heating rate is 3℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain a lithium-rich manganese-based substrate cathode material:

[0087] 0.5Li2Mn 0.995 W 0.005 O3·0.5LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 O2.

[0088] Example 2

[0089] The method for preparing the lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0090] (1) Weigh 537.3g of lithium hydroxide LiOH·H2O (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 351.9g of manganese tetroxide Mn3O4, 242.1g of cobalt oxide Co2O3 and 12.3g of titanium dioxide TiO2, add each raw material to a sand mill, add 2200mL of deionized water, mix evenly and obtain a slurry.

[0091] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.2L / min, the inlet air temperature of the spray drying is 120℃, the outlet air temperature is 80℃, and the carrier gas rate is 10L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0092] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 300℃ for 8 hours with a heating rate of 5℃ / min; then, it is heated to 800℃ for 30 hours with a heating rate of 5℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0093] (4) The calcined material obtained in step (3) is mixed evenly in a double cone mixer, and then calcined a second time in an air atmosphere furnace (i.e., the second calcination). The calcination temperature is 500℃, the calcination time is 2h, and the heating rate is 10℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based substrate cathode material 0.6Li2Mn. 0.98 Ti 0.02 O3·0.4LiCo 0.98 Ti 0.02 O2.

[0094] Example 3

[0095] The method for preparing the lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0096] (1) Weigh 782.9g of lithium nitrate LiNO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 158g of manganese dioxide MnO2, 542.3g of cobalt oxide Co2O3 and 60.4g of niobium oxide Nb2O5, add each raw material to a sand mill, add 800mL of deionized water, mix evenly and obtain a slurry.

[0097] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 5L / min, the inlet air temperature of the spray drying is 300℃, the outlet air temperature is 250℃, and the carrier gas rate is 200L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0098] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 500℃ for 3 hours with a heating rate of 4℃ / min; then, it is heated to 950℃ for 10 hours with a heating rate of 4℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0099] (4) The calcined material obtained in step (3) is mixed evenly in a plowshare mixer, and then calcined a second time in an air atmosphere furnace (i.e., the second calcination). The calcination temperature is 900℃, the calcination time is 2h, and the heating rate is 1℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based basal cathode material 0.2Li2Mn. 0.95 Nb 0.05 O3·0.8LiCo 0.95 Nb 0.05 O2.

[0100] Example 4

[0101] The method for preparing the lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0102] (1) Weigh 524.2g of lithium hydroxide LiOH·H2O (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 347.7g of manganese dioxide MnO2, 311.3g of nickel trioxide Ni2O3 and 34.4g of cerium oxide CeO2, add each raw material to a sand mill, add 2400mL of methanol, mix evenly and obtain a slurry.

[0103] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 3L / min, the inlet air temperature of the spray drying is 280℃, the outlet air temperature is 120℃, and the carrier gas rate is 180L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0104] (3) The powder obtained in step (2) is placed in an oxygen atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 450℃ for 6 hours with a heating rate of 10℃ / min; then, it is heated to 750℃ for 30 hours with a heating rate of 10℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0105] (4) The calcined material obtained in step (3) is mixed evenly in a planetary ball mill, and then calcined a second time in an oxygen atmosphere furnace (i.e., the second calcination). The calcination temperature is 700℃, the calcination time is 10h, and the heating rate is 10℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based substrate cathode material 0.5Li2Mn. 0.975 Ce 0.025 O3·0.5LiNi 0.975 Ce 0.025 O2.

[0106] Example 5

[0107] The method for preparing lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0108] (1) Weigh 434.8g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 428.7g of manganese tetroxide Mn3O4, 222.5g of nickel oxide NiO and 19.2g of tantalum oxide Ta2O5, add each raw material to a sand mill, add 1200mL of anhydrous ethanol, mix evenly and obtain a slurry.

[0109] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 3L / min, the air inlet temperature is 150℃, the air outlet temperature is 120℃, and the carrier gas rate is 150L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0110] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 550℃ for 8 hours with a heating rate of 2℃ / min; then, it is heated to 850℃ for 22 hours with a heating rate of 2℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0111] (4) The calcined material obtained in step (3) is mixed evenly in a double cone mixer, and then calcined a second time in an air atmosphere furnace (i.e., the second calcination). The calcination temperature is 850℃, the calcination time is 5h, and the heating rate is 5℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based substrate cathode material 0.3Li2Mn. 0.99 Ta 0.01 O3·0.7LiNi 0.495 Mn 0.495 Ta 0.01 O2.

[0112] Example 6

[0113] The method for preparing lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0114] (1) Weigh 493.6g of lithium hydroxide LiOH·H2O (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 425.5g of manganese tetroxide Mn3O4, 244.1g of nickel trioxide Ni2O3, 6.9g of titanium oxide TiO2 and 5.3g of zirconium oxide ZrO2, add each raw material to a sand mill, add 600mL of deionized water, mix evenly and obtain a slurry.

[0115] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 280℃, the outlet air temperature is 120℃, and the carrier gas rate is 120L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0116] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 300℃ for 8 hours with a heating rate of 3℃ / min; then, it is heated to 920℃ for 14 hours with a heating rate of 3℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0117] (4) The calcined material obtained in step (3) is mixed evenly in a high-speed mixer, and then calcined a second time in an air atmosphere furnace (i.e., the second calcination). The calcination temperature is 750℃, the calcination time is 5h, and the heating rate is 5℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based substrate cathode material 0.3Li2Mn. 0.985 Ti 0.01 Zr 0.005 O3·0.7LiNi 0.4925 Mn 0.4925 Ti 0.01 Zr0.005 O2.

[0118] Example 7

[0119] The method for preparing the lithium-rich manganese-based substrate cathode material provided in this embodiment includes the following steps:

[0120] (1) Weigh 427.1g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 247.6g of MnSO4·4H2O, 562.2g of CoSO4·7H2O, 1051.4g of NiSO4·6H2O, 33.9g of Al2O3 and 9.7g of molybdenum oxide MoO3, add each raw material to a sand mill, add 4500mL of deionized water, mix evenly and obtain a slurry.

[0121] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 300℃, the outlet air temperature is 100℃, and the carrier gas rate is 30L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0122] (3) The powder obtained in step (2) is placed in an oxygen atmosphere furnace for two-step calcination (i.e., two-stage calcination). First, it is calcined at 400℃ for 6 hours with a heating rate of 5℃ / min; then, it is heated to 750℃ for 30 hours with a heating rate of 5℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0123] (4) The calcined material obtained in step (3) is mixed evenly in a plow mixer, and then calcined a second time in an air atmosphere furnace (i.e., the second calcination). The calcination temperature is 500℃, the calcination time is 10h, and the heating rate is 1℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain the lithium-rich manganese-based basal cathode material 0.25Li2Mn. 0.99 Mo 0.01 O3·0.75LiNi 0.594 Co 0.297 Al 0.099 Mo 0.01 O2.

[0124] Comparative Example 1

[0125] The preparation method of the lithium-rich manganese-based basal cathode material provided in this comparative example is basically the same as that in Example 1, except that in step (4), there is no step of uniform mixing and second calcination.

[0126] Comparative Example 2

[0127] The preparation method of the lithium-rich manganese-based basal cathode material provided in this comparative example is basically the same as that in Example 1, except that tungsten oxide WO3 was not added in step (1).

[0128] Comparative Example 3

[0129] The method for preparing the lithium-rich manganese-based substrate cathode material provided in this comparative example includes the following steps:

[0130] (1) Weigh 411.7g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 348.1g of manganese dioxide MnO2, 195.5g of cobalt oxide CoO, 192.9g of nickel oxide NiO and 9.3g of tungsten oxide WO3, add each raw material to a sand mill, add 1000mL of anhydrous ethanol, mix evenly and obtain a slurry.

[0131] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 250℃, the outlet air temperature is 120℃, and the carrier gas rate is 50L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0132] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e. two-stage calcination). First, it is calcined at 500℃ for 4 hours with a heating rate of 3℃ / min. Then, it is heated to 850℃ for 20 hours with a heating rate of 3℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0133] (4) The calcined material obtained in step (3) is mixed evenly (i.e., evenly dispersed) in a high-speed mixer, and then calcined a second time in an air atmosphere furnace (i.e., second calcination). The calcination temperature is 700℃, the calcination time is 5h, and the heating rate is 3℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain a lithium-rich manganese-based substrate cathode material:

[0134] 0.15Li2Mn 0.995 W 0.005 O3·0.85LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 O2.

[0135] In this comparative example, n = 0.15.

[0136] Comparative Example 4

[0137] The preparation method of the lithium-rich manganese-based substrate cathode material provided in this comparative example includes the following steps:

[0138] (1) Weigh 479.2g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 502.2g of manganese dioxide MnO2, 65.3g of cobalt oxide CoO, 64.4g of nickel oxide NiO and 9.3g of tungsten oxide WO3, add each raw material to a sand mill, add 1000mL of anhydrous ethanol, mix evenly and obtain a slurry.

[0139] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 250℃, the outlet air temperature is 120℃, and the carrier gas rate is 50L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0140] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e. two-stage calcination). First, it is calcined at 500℃ for 4 hours with a heating rate of 3℃ / min. Then, it is heated to 850℃ for 20 hours with a heating rate of 3℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0141] (4) The calcined material obtained in step (3) is mixed evenly (i.e., evenly dispersed) in a high-speed mixer, and then calcined a second time in an air atmosphere furnace (i.e., second calcination). The calcination temperature is 700℃, the calcination time is 5h, and the heating rate is 3℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain a lithium-rich manganese-based substrate cathode material:

[0142] 0.65Li₂Mn 0.995 W 0.005 O3·0.35LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 O2.

[0143] In this comparative example, n = 0.65.

[0144] Comparative Example 5

[0145] The preparation method of the lithium-rich manganese-based basal cathode material provided in this comparative example includes the following steps:

[0146] (1) Weigh 461.8g of lithium carbonate Li2CO3 (4wt.% excess to compensate for the loss of lithium volatilization during high-temperature sintering), 537.9g ​​of manganese dioxide MnO2, 67.2g of cobalt oxide CoO, 66.3g of nickel oxide NiO and 9.3g of tungsten oxide WO3, add each raw material to a sand mill, add 1000mL of anhydrous ethanol, mix evenly and obtain a slurry.

[0147] (2) The slurry obtained in step (1) is pumped into the spray drying equipment by a peristaltic pump for spray drying. The liquid inlet rate is 0.8L / min, the inlet air temperature of the spray drying is 250℃, the outlet air temperature is 120℃, and the carrier gas rate is 50L / min. During the drying process, the solvent in the slurry evaporates to obtain a powder with a uniform mixture of multiple metal elements (i.e., a mixture containing Li source, Mn source, X source and A source).

[0148] (3) The powder obtained in step (2) is placed in an air atmosphere furnace for two-step calcination (i.e. two-stage calcination). First, it is calcined at 500℃ for 4 hours with a heating rate of 3℃ / min. Then, it is heated to 850℃ for 20 hours with a heating rate of 3℃ / min. After the two-step calcination is completed, it is cooled with the furnace to obtain the calcined material.

[0149] (4) The calcined material obtained in step (3) is mixed evenly (i.e., evenly dispersed) in a high-speed mixer, and then calcined a second time in an air atmosphere furnace (i.e., second calcination). The calcination temperature is 700℃, the calcination time is 5h, and the heating rate is 3℃ / min. After cooling in the furnace, the product is crushed and sieved to obtain a lithium-rich manganese-based substrate cathode material:

[0150] 0.5Li2Mn 0.995 W 0.005 O3·0.5LiNi 0.224 Co 0.224 Mn 0.547 W 0.005 O2.

[0151] In this comparative example, b = 0.547.

[0152] Comparative Example 6

[0153] (1) Synthesis of the first phase Li2Mn 0.995 W 0.005 O3 material: The preparation method is basically the same as in Example 1, except that in step (1), the mass of Li2CO3 is replaced with 307.8g, the mass of MnO2 is replaced with 346.9g, the mass of WO3 is replaced with 4.65g, and no cobalt oxide CoO and nickel oxide NiO are added; at the same time, in step (4), there is no step of uniform mixing and second calcination.

[0154] (2) Synthesis of second-phase LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 Materials: The preparation method is basically the same as in Example 1, except that in step (1), the mass of Li2CO3 is replaced with 153.9g, the mass of MnO2 is replaced with 115.6g, and the mass of WO3 is replaced with 4.65g; at the same time, in step (4), there is no step of uniform mixing and second calcination.

[0155] (3) The first phase Li2Mn synthesized in step (1) of this comparative example 0.995 W 0.005 O3 materials and steps (2) for the synthesis of LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 The materials were mixed evenly (i.e., evenly dispersed) in a high-speed mixer, and then calcined a second time in an air atmosphere furnace at 700℃ for 5 hours at a heating rate of 3℃ / min. After cooling in the furnace, the product was pulverized and sieved to obtain a lithium-rich manganese-based substrate cathode material.

[0156] 0.5Li2Mn 0.995 W 0.005 O3·0.5LiNi 0.3317 Co 0.3317 Mn 0.3316 W 0.005 O2.

[0157] Experimental Example

[0158] The absolute value of the lattice microstrain ST of the lithium-rich manganese-based substrate cathode materials prepared in the above embodiments and comparative examples, |ST|, and Li2Mn 1-a A a The absolute value of the lattice microstrain of O3, |ST1|, and LiMn b X c A a The absolute values ​​of the lattice microstrain |ST2| of O2 are shown in Table 1.

[0159] The lithium-rich manganese-based substrate cathode materials prepared in each embodiment and comparative example were subjected to physicochemical characterization tests. The test results are shown in Table 1, and the test methods are as follows:

[0160] Morphological characterization: The morphology of the samples was observed using a scanning electron microscope (SEM).

[0161] Test method for average particle size D50: The particle size was tested using a Mastersizer3000 laser particle size analyzer with pure water as the dispersion medium and ultrasonication for 1 min. The test parameters were set with an absorptivity of 0.1 and a refractive index of 1.52 to obtain the volume distribution curve of particle size and the average particle size D50.

[0162] The method for testing the median particle size D50 of primary particles: Primary particles in SEM images were labeled using Nano Measurer software, and size statistical analysis was performed to obtain the median particle size of primary particles.

[0163] Specific surface area testing method: The specific surface area of ​​each sample was determined using a specific surface area analyzer and the nitrogen low-temperature adsorption method.

[0164] Test methods for LiOH content and Li2CO3 content: Refer to GB / T 41704-2022.

[0165] ICP testing method: Dissolve the cathode material sample in HCl to prepare a solution of a certain concentration, and use inductively coupled plasma atomic emission spectrometry to test the content of metal elements in the material.

[0166] Material structure characterization and analysis: XRD testing was performed using a Cu-Kα target with an emission wavelength λ = 0.1548 nm, a scanning voltage of 40 kV, a current of 40 mA, a step-scan mode, a scanning speed of 1° / min, and a scanning range of 10°–80°. The Li₂Mn content in the structure was further refined using Rietveld analysis. 1-a A a O3 phase and LiMn b X c A a The two-phase ratio of O2 phase, and the error in the refined data R. wp ≤10.0% is a valid value, resulting in the expression nLi2Mn. 1-a A a O3·(1-n)LiMn b X c A a The value of n in O2.

[0167] Calculation of microscopic strain of material lattice: LeBail fitting was performed on the measured XRD of lithium-rich manganese-based substrate cathode material, using C2 / m Li2Mn. 1-a A a Using the unit cell parameters of the O3 phase and the R-3m LiNiO2 phase as constraints, based on the uniform deformation model of the crystal structure and the Williamson-Hall equation, it can be known that β hkl·cosθ=kλ / D+4ε·sinθ (Refer to Materials Chemistry and Physics, 2020, 239, 122021), where β hkl In the XRD pattern, β represents the full width at half maximum (FWHM) of the (hkl) crystal plane, θ is the half diffraction angle, D is the grain size, and ε is the lattice strain (ST). In the Williamson-Hall pattern, β... hkl The cosθ value is the ordinate and the sinθ value is the abscissa. Therefore, the lattice micro-strain ε can be solved using the slope.

[0168] Table 1. Lattice microstrain and physicochemical characterization results of lithium-rich manganese-based bulk cathode materials

[0169]

[0170]

[0171] Furthermore, coin-type lithium secondary batteries were fabricated using the lithium-rich manganese-based substrate cathode materials prepared in each embodiment and comparative example, and their electrochemical performance was tested. The test results are shown in Table 2.

[0172] The specific manufacturing method of the lithium secondary battery and its positive electrode sheet is as follows: A lithium-rich manganese-based substrate positive electrode material is mixed with acetylene black, carbon nanotubes, and polyvinylidene fluoride in a mass ratio of 90:4:1:5. An appropriate amount of N-methylpyrrolidone is added as a dispersant, and the mixture is ground into a slurry. The slurry is then uniformly coated onto aluminum foil and vacuum dried at 120°C for 10 hours. The dried electrode sheet is then rolled using a roller press, and the aluminum foil is cut into circular electrode sheets with a diameter of 1.3 cm using a slicing machine. The loading of the active material is controlled at 10 mg·cm³. -2 Half-cells were assembled in an argon-atmospheric glove box with a water partial pressure ≤0.1ppm and an oxygen partial pressure ≤0.1ppm. Using lithium metal as the counter electrode and a 1M LiPF6 (FEC / EC / DMC, volume ratio 1:3:6) solution as the electrolyte, CR2032 coin cells were assembled. Constant current charge-discharge testing was conducted at room temperature with a voltage range of 2.0-4.65V and a current density of 25mA / g (0.1C). The first-cycle charge specific capacity, first-cycle discharge specific capacity, and first-cycle coulombic efficiency were recorded. Subsequently, a cycle test was performed at a current density of 0.33C. After 100 cycles, the battery capacity retention, average discharge decay, and positive electrode material energy density retention were recorded, where the positive electrode material energy density = discharge specific capacity × average discharge voltage.

[0173] Table 2. Electrical performance test results of lithium secondary batteries prepared from various lithium-rich manganese-based substrate cathode materials.

[0174]

[0175]

[0176] As shown in Tables 1 and 2, the lithium-rich manganese-based substrate cathode material provided by this invention, through the construction of Li2Mn with C2 / m space groups, achieves high efficiency. 1-a A a LiMn in O3 and R-3m space groups b X c A a The two-phase low-strain dispersed symbiotic structure of O2 precisely controls the lattice micro-strain of different phases (ST1, ST2) and the composite cathode material (ST), improving the reversibility and recoverability of the anion oxidation and reduction reactions. The lithium-rich manganese-based substrate cathode materials prepared in each embodiment exhibit higher first-cycle coulombic efficiency, and after 100 cycles, the specific capacity and specific energy retention are significantly higher than those of the respective comparative examples, and the voltage decay is significantly suppressed.

[0177] As can be seen, the lithium-rich manganese-based substrate cathode material provided by this invention, through optimization of material composition and synthesis process, regulates the Li2Mn content. 1-a A a O3 phase, LiMn b X c A a The O2 phase and the lattice micro-strain of lithium-rich manganese-based substrate cathode materials can improve the first-cycle coulombic efficiency of cathode materials, enhance the capacity and voltage retention rate during long-term cycling, and suppress capacity and voltage decay during cycling.

[0178] Furthermore, Figure 1 The image shows the XRD pattern of the lithium-rich manganese-based substrate cathode material prepared in Example 1. Figure 1 It can be seen that, except for Li2Mn belonging to the C2 / m spatial point group between 20° and 25°, 1-a A a Apart from the weaker diffraction peaks of the O3 structure, the remaining diffraction peaks correspond to the hexagonal layered R-3m structure. The crystal plane index is indicated by the subscript "H" for the hexagonal layered R-3m structure and "M" for the monoclinic C2 / m structure. Furthermore, as shown in Table 1, the Rietveld refinement results indicate that the fitting error R... wp The content of Li2Mn in the material is relatively low, at 7.55%. 1-a A a O3 phase and LiMn b X c A a The proportions of O2 layered phases were 0.495 and 0.505, respectively.

[0179] Figure 2The Williamson-Hall diagrams of the two phases in the lithium-rich manganese-based substrate cathode material prepared in Example 1 are shown. Based on the Williamson-Hall equation β... hkl From cosθ=kλ / D+4ε·sinθ, it can be seen that the lattice micro-strain ε is proportional to the slope in the figure. The LiMn crystals in Example 1 were calculated using the (003), (101), (104), (015), (107) crystal planes of the hexagonal phase and the (002), (200), (202), (133), (204) crystal planes of the monoclinic phase. b X c A a O2 phase and Li2Mn 1-a A a The micro-strain values ​​in the O3 phase were 0.030% and 0.048%, respectively.

[0180] Figure 3 The image shows the SEM image of the lithium-rich manganese-based basal cathode material prepared in Example 1. It can be seen that the cathode material is a secondary sphere formed by the agglomeration of primary particles with a particle size of about 300 nm. The median particle size D50 of the lithium-rich manganese-based basal cathode material is about 10 μm.

[0181] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A lithium-rich manganese-based substrate cathode material, characterized in that, The lithium-rich manganese-based substrate cathode material includes a first phase Li2Mn with space group C2 / m. 1-a A a O3 and the second phase LiMn with space group R-3m b X c A a O2, the general formula of the lithium-rich manganese-based substrate cathode material is nLi2Mn 1-a A a O3•(1-n)LiMn b X c A a O2; Among them, 0.2 ≤ n ≤ 0.6, 0 < a ≤ 0.05, 0 ≤ b ≤ 0.5, 0 ≤ c < 1, and a + b + c = 1; X includes at least one of Ni, Co, and Al elements, and A includes at least one of Ti, Zr, Ce, Mo, Nb, Ta, and W elements; The absolute value of the lattice micro-strain of the first phase |ST1| ≤ 0.25%, and the absolute value of the lattice micro-strain of the second phase |ST2| ≤ 0.20%; the lattice micro-strain ST of the lithium-rich manganese-based layered cathode material is ST = n•ST1 + exp(b)•(1 - n)•ST2, and the absolute value of the ST |ST| ≤ 0.20%.

2. The lithium-rich manganese-based substrate cathode material according to claim 1, characterized in that, The median particle size D50 of the lithium-rich manganese-based layered cathode material is 2 - 15 μm; And / or, the lithium-rich manganese-based layered cathode material includes secondary particles aggregated by primary particles, and the median particle size D50 of the primary particles is 20 - 500 nm.

3. The lithium-rich manganese-based substrate cathode material according to claim 1, characterized in that, The lithium-rich manganese-based layered cathode material includes at least one of the following features (1) to (3): (1) The specific surface area of ​​the lithium-rich manganese-based substrate cathode material is 0.3~6.0 m². 2 / g; (2) The LiOH content in the lithium-rich manganese-based layered cathode material ≤ 2500 ppm; (3) The Li2CO3 content in the lithium-rich manganese-based layered cathode material ≤ 2500 ppm.

4. The method for preparing the lithium-rich manganese-based substrate cathode material according to any one of claims 1 to 3, characterized in that, It includes the following steps: The mixed material containing Li source, Mn source, X source, and A source is calcined in two stages to obtain a calcined material; the calcined material is calcined a second time to obtain the lithium-rich manganese-based layered cathode material; The X source includes a compound containing X, where X includes at least one of Ni, Co, and Al elements; The A source includes a compound containing A, where A includes at least one of Ti, Zr, Ce, Mo, Nb, Ta, and W elements.

5. The method for preparing the lithium-rich manganese-based substrate cathode material according to claim 4, characterized in that, The two-stage calcination includes: first keeping the temperature at 300 - 600 °C for 2 - 8 h, and then keeping the temperature at 750 - 950 °C for 12 - 30 h; And / or, the second calcination includes: keeping the temperature at 500 - 900 °C for 2 - 10 h.

6. The method for preparing the lithium-rich manganese-based substrate cathode material according to claim 4, characterized in that, The atmosphere of the second calcination includes an oxygen-containing atmosphere; And / or before the second calcination, there is also a step of uniformly dispersing the calcined material.

7. The method for preparing the lithium-rich manganese-based substrate cathode material according to claim 4, characterized in that, 8. A positive electrode sheet, characterized in that, The preparation method of the mixed material containing Li source, Mn source, X source, and A source includes: mixing the Li source, the Mn source, the X source, the A source, and a solvent uniformly to obtain a slurry; spray-drying the slurry to obtain the mixed material containing Li source, Mn source, X source, and A source.

9. A lithium-ion battery, characterized in that, It includes the lithium-rich manganese-based layered cathode material according to any one of claims 1 to 3.

10. Electrical equipment, characterized in that, It includes the positive electrode sheet according to claim 8. It includes the lithium-ion battery according to claim 9.

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