A lithium-rich manganese-based material, a preparation method and application thereof

Abstract

Li n Ni x Mn y Ti a Mo b This application specifically discloses a lithium-rich manganese-based material, its preparation method, and its application. A method for preparing a lithium-rich manganese-based material, wherein the general chemical formula of the lithium-rich manganese-based material is Li. n Ni x Mn y Ti a Mo b O2, where 1.0 < n < 1.5, 0.2 < x < 0.4, 0.5 < y < 0.8, 0.001 < a < 0.01, 0.01 < b < 0.1; the preparation method includes the following steps: S1: dissolving nickel and manganese sources in water to obtain metal salt solution A, dissolving titanium and molybdenum sources in water to obtain metal salt solution B, mixing metal salt solution B with metal salt solution A to obtain metal salt solution C, mixing metal salt solution C with a precipitant and a complexing agent to obtain a mixed salt solution, the mixed salt solution undergoes a temperature-changing operation followed by a isothermal reaction, and then solid-liquid separation and drying are performed to obtain a precursor; S2: mixing the precursor obtained in S1 with a lithium source, grinding, and calcining to obtain a lithium-rich manganese-based material. This application has the advantages of improving the conductivity of lithium-rich manganese-based materials and improving the high-temperature resistance of lithium batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a lithium-rich manganese-based material, its preparation method, and its application. Background Technology

[0002] With the continuous development of the new energy field, lithium-ion batteries, due to their high energy density, light weight, and pollution-free characteristics, are gradually being applied to all aspects of human life. As the application scope of lithium-ion batteries expands, higher demands are being placed on their energy density. The cathode material in a lithium-ion battery is a key factor affecting its energy density. Currently mature cathode materials such as lithium cobalt oxide, lithium spinel manganese oxide, lithium iron phosphate, and ternary materials like lithium nickel cobalt manganese oxide are insufficient to meet the high specific energy requirements of electric vehicles and other fields. Therefore, there is an urgent need to provide a cathode material with high energy density, low production cost, and excellent safety performance.

[0003] Lithium-rich manganese-based materials can achieve 250 mAh / g. -1 Its electrochemical specific capacity can even reach 300 mAh.g -1 Furthermore, due to the low price of manganese, it can reduce the production cost of lithium-rich manganese-based materials, thus gradually gaining widespread attention and is expected to replace existing mature cathode materials.

[0004] However, lithium-rich manganese-based materials also have many problems. For example, they contain two main phases, namely Li₂MnO₃ and LiMO₂ (M = Mn, Ni, Co, etc.), both of which are layered α-NaFeO₂ type rock salt structures. Therefore, the powder resistivity of lithium-rich manganese-based materials is 10 Ω·cm. 7 -10 8 The resistivity of lithium-rich manganese-based materials is low (Ω·cm), resulting in poor conductivity and high DC resistance in lithium-ion batteries assembled from them. This negatively impacts the battery's cycle performance, storage capacity, and other electrical properties. Currently, the conventional method to control the powder resistivity of lithium-rich manganese-based materials is to add highly conductive compounds, such as graphene, during the sintering process. However, the sintering process cannot uniformly deposit conductive compounds onto the surface of the lithium-rich manganese-based materials, leading to poor results in improving the conductivity of these materials. Summary of the Invention

[0005] To improve the conductivity of lithium-rich manganese-based materials and enhance the high-temperature resistance of lithium batteries, this application provides a lithium-rich manganese-based material, its preparation method, and its application.

[0006] In a first aspect, this application provides a method for preparing lithium-rich manganese-based materials, employing the following technical solution:

[0007] A method for preparing lithium-rich manganese-based materials, wherein the general chemical formula of the lithium-rich manganese-based materials is Li.n Ni x Mn y Ti a Mo b O2, where 1.0 < n < 1.5, 0.2 < x < 0.4, 0.5 < y < 0.8, 0.001 < a < 0.01, 0.01 < b < 0.1; for example, n can be 1.1, 1.3, 1.4, x can be 0.21, 0.3, 0.39, y can be 0.51, 0.7, 0.78, a can be 0.002, 0.006, 0.009, and b can be 0.02, 0.05, 0.09, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0008] The preparation method includes the following steps:

[0009] S1: Dissolve nickel source and manganese source in water to obtain metal salt solution A, dissolve titanium source and molybdenum source in water to obtain metal salt solution B, mix metal salt solution B with metal salt solution A to obtain metal salt solution C, mix metal salt solution C with precipitant and complexing agent to obtain mixed salt solution, and then perform temperature-controlled operation, followed by solid-liquid separation and drying to obtain precursor;

[0010] S2: The precursor obtained in S1 is mixed with a lithium source, ground, and calcined to obtain the lithium-rich manganese-based material;

[0011] The temperature-changing operation in S1 includes the following steps: cooling the mixed salt solution to below 0°C and then heating it back to above 0°C. For example, the temperature can be lowered to -10°C, -20°C, -50°C, or -60°C, and the temperature can be raised to 10°C, 40°C, 50°C, or 70°C, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] This application achieves several advantages by doping lithium-rich manganese-based materials with titanium and molybdenum. First, Ti doping allows for mixing with Ni metal to form a stable, disordered layered phase structure, which further promotes lithium-ion transport and reduces lithium-ion diffusion resistance. Mo doping lowers the valence state of Mn, thereby reducing its sedimentation rate and decreasing the size of primary particles formed during preparation. The smaller primary particle size, in turn, increases the specific surface area of ​​the particles, further shortening the lithium-ion transport distance and reducing lithium-ion diffusion resistance. Second, titanium and molybdenum doping significantly improves the powder conductivity of lithium-rich manganese-based materials. Since titanium and molybdenum have low electrochemical potentials, they facilitate lithium-ion transfer between the positive and negative electrodes, thereby improving the cycle performance and high-temperature storage performance of lithium-rich manganese-based materials. Third, using… In the preparation of the precursor by the method of this application, nickel, manganese, titanium, and molybdenum can co-precipitate, which solves the problem of uneven doping of titanium and molybdenum in lithium-rich manganese-based materials. Furthermore, the mixing of the salt solution achieves atomic-level uniform mixing, which further helps to improve the powder resistivity of lithium-rich manganese-based materials. Fourth, in the preparation process of the precursor of this application, the mixed salt solution is first cooled to below 0°C, causing a small amount of water of crystallization or ice to appear inside and on the surface of the product. After heating to above 0°C, the water of crystallization melts or the ice sublimates, thereby generating a small number of pores inside and on the surface of the reaction product, resulting in a reaction product with a loose structure and doped with titanium and molybdenum. This further reduces the impedance of the precursor, which is beneficial to improving the conductivity and high-temperature storage performance of lithium batteries. Fifth, the lithium-rich manganese-based material prepared by this application does not contain cobalt, which can significantly reduce the application cost of lithium-rich manganese-based materials.

[0013] Preferably, step S1 includes: stirring the metal salt solution A, then adding the metal salt solution B dropwise to the metal salt solution A, adjusting the pH and temperature of the reaction system to obtain the metal salt solution C; adding the precipitant and the complexing agent dropwise to the metal salt solution C in sequence, adjusting the pH of the reaction system to obtain the mixed salt solution;

[0014] The temperature-changing operation includes the following steps: First, the mixed salt solution is cooled to -10℃ to 0℃ and stirred at 100-150 rpm for 60-90 minutes. For example, the temperature can be lowered to -10℃, -5℃, or -1℃, and the stirring speed can be 100 rpm, 130 rpm, or 150 rpm. The stirring time can be 60 minutes, 80 minutes, or 90 minutes, but is not limited to the listed values; other unlisted values ​​within the range are also applicable. Then, the temperature is raised to 45-60℃ and stirred at 50-100 rpm. For example, the temperature can be raised to 45℃, 50℃, or 60℃, and the stirring speed can be 50 rpm, 80 rpm, or 100 rpm, but is not limited to the listed values; other unlisted values ​​within the range are also applicable. After the temperature rise, the temperature is maintained at 45-60℃ for 60-90 minutes. For example, the holding temperature can be 45℃, 50℃, or 60℃, and the holding time can be... The timeframes are 60 min, 80 min, and 90 min, but are not limited to the listed values; other unlisted values ​​within the range are also applicable. Alternatively, the mixed salt solution is frozen at -50°C to -60°C and a vacuum of 20-40 Pa for 22-26 hours. For example, the temperature can be lowered to -50°C, -55°C, or -60°C, the vacuum can be 20 Pa, 30 Pa, or 40 Pa, and the freezing time can be 22 hours, 24 hours, or 26 hours, but are not limited to the listed values; other unlisted values ​​within the range are also applicable. Subsequently, the precursor is dried at 45-60°C and a vacuum of 95-105 Pa for 22-26 hours to obtain the precursor. For example, the temperature can be raised to 45°C, 50°C, or 60°C, the vacuum can be 95 Pa, 100 Pa, or 105 Pa, and the drying time can be 22 hours, 24 hours, or 26 hours, but are not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0015] By subjecting the mixed salt solution to a variable temperature operation—first cooling it to -10°C to 0°C and then heating it to 45-60°C—a small amount of water of crystallization is generated on the surface and inside the reaction products. Upon heating, this water of crystallization melts, creating a certain number of pores on the surface and inside the reaction products. Conversely, by first cooling the mixed salt solution to -50°C to -60°C and then heating it to 45-60°C, a small amount of ice is generated on the surface and inside the reaction products. Upon heating, this ice sublimates, creating a certain number of pores on the surface and inside the reaction products. This variable temperature operation helps to adjust the internal structure of the precursor, thereby obtaining a precursor with a designable internal structure.

[0016] Preferably, the metal salt solution A is stirred at 50-80 rpm at 40-70°C. For example, the temperature can be 40°C, 50°C, or 70°C, and the stirring speed can be 50 rpm, 70 rpm, or 80 rpm, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] The dropping rate of the metal salt solution B is 4-10 mL / min. Before obtaining the metal salt solution C, the pH of the reaction system is adjusted to 8-9 and the reaction temperature is 50-60℃. For example, the dropping rate can be 4 mL / min, 6 mL / min, or 10 mL / min, the pH can be 8, 8.5, or 9, and the reaction temperature can be 50℃, 55℃, or 60℃, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] The dropping rate of both the precipitant and the complexing agent is 2-10 mL / min. Before obtaining the mixed salt solution, the pH of the reaction system is adjusted to 9-11. For example, the dropping rate can be 2 mL / min, 6 mL / min, or 10 mL / min, and the pH can be 9, 10, or 11, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] By controlling the dropping rates of the metal salt solution B, the precipitant, and the complexing agent, the elements can react fully, allowing molybdenum and titanium to be uniformly doped into the precursor. This is beneficial for generating a precursor with high elemental uniformity and improving the structural stability of the precursor. This not only helps to further improve the powder resistivity of lithium-rich manganese-based materials but also improves the high-temperature cycling performance and high-temperature storage performance of lithium-rich manganese-based materials.

[0020] Preferably, the metal salt solution A is prepared by dissolving nickel and manganese sources in water according to a stoichiometric ratio x:y, wherein the concentration of metal salt solution A is 0.5-5 mol / L, for example, 0.5 mol / L, 1 mol / L, 2 mol / L, 4 mol / L, or 5 mol / L, but not limited to the listed values; other unlisted values ​​within the range are also applicable. The metal salt solution B is prepared by dissolving titanium and molybdenum sources in water according to a stoichiometric ratio a:b, wherein the concentration of metal salt solution B is 0.01-0.1 mol / L, for example, 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, or 0.01 mol / L. The concentrations are 0.08 mol / L, 0.1 mol / L, but not limited to the listed values; other unlisted values ​​within the range are also applicable. The concentration of the precipitant is 1-10 mol / L, for example, 1 mol / L, 3 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, but not limited to the listed values; other unlisted values ​​within the range are also applicable. The concentration of the complexing agent is 0.5-5 mol / L, for example, 0.5 mol / L, 1 mol / L, 2 mol / L, 4 mol / L, 5 mol / L, but not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0021] Preferably, the precursor comprises at least one of MCO3 and M(OH)2, wherein M represents Ni, Mn, Ti, and Mo; the particle size D50 of the precursor is 5-10 μm, the particle size distribution of the precursor satisfies 0.3≤(D90-D10) / D50≤0.8, and the specific surface area of ​​the precursor is 15-40 m². 2 / g, for example, the particle size can be 5μm, 7μm, 10μm, the particle size distribution can be 0.3, 0.5, 0.8, and the specific surface area can be 15m². 2 / g、25m 2 / g、40m 2 / g, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0022] By controlling the particle size distribution and specific surface area of ​​the precursor, it is beneficial to sinter the precursor and the lithium source, generating lithium-rich manganese-based materials with high specific surface area and suitable particle size distribution. This helps to generate channels that facilitate ion and electron transport when the lithium-rich manganese-based materials are applied in the positive electrode active layer, thereby improving the conductivity of the lithium-rich manganese-based materials.

[0023] Preferably, in step S2, the molar ratio of the lithium source to the precursor is 1.1-1.4:1, for example, it can be 1.1:1, 1.3:1, or 1.4:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, step S2 includes: mixing the precursor with the lithium source and grinding them to obtain a first mixed powder; sintering the first mixed powder once to obtain a first sintered sample; pulverizing the first sintered sample to obtain a second mixed powder; sintering the second mixed powder a second time to obtain a second sintered sample; and pulverizing the second sintered sample to obtain the lithium-rich manganese-based material.

[0025] Distributed sintering can improve the bonding stability between the lithium source and the precursor, which helps to prepare lithium-rich manganese-based materials with stable structure and performance.

[0026] Preferably, the primary sintering is carried out in an oxygen-containing inert atmosphere, wherein the oxygen concentration in the oxygen-containing inert atmosphere is 80%-95%, for example, 80%, 85%, or 95%, but not limited to the listed values; other unlisted values ​​within the range are also applicable. During the primary sintering process, the first mixed powder is first heated to 500-550℃ at a heating rate of 5-10℃ / min and held at that temperature for 5-10 hours. For example, the heating rate can be 5℃ / min, 8℃ / min, or 10℃ / min; the heating temperature can be 500℃, 520℃, or 550℃; and the holding time can be 5 hours, 8 hours, or 10 hours, but not limited to the listed values; other unlisted values ​​within the range are also applicable. The values ​​not listed also apply. The mixture is then heated to 800-900℃ at a heating rate of 15-30℃ and held at that temperature for 5-10 hours. For example, the heating rate can be 15℃ / min, 20℃ / min, or 30℃ / min; the heating temperature can be 800℃, 850℃, or 900℃; and the holding time can be 5 hours, 8 hours, or 10 hours, but is not limited to the listed values. Other unlisted values ​​within the range also apply. After the holding time is completed, the mixture is allowed to cool naturally to obtain the first sintered sample. The particle size of the second mixed powder is 1-10 μm, for example, it can be 1 μm, 5 μm, or 10 μm, but is not limited to the listed values. Other unlisted values ​​within the range also apply.

[0027] The secondary sintering is carried out in an oxygen-containing inert atmosphere, wherein the oxygen concentration in the oxygen-containing inert atmosphere is 80%-99%, for example, it can be 80%, 90%, 99%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. In the secondary sintering process, the second mixed powder is first heated to 300-450℃ at a heating rate of 5-10℃ / min and held at that temperature for 2-5 hours. For example, the heating rate can be 5℃ / min, 7℃ / min, 10℃ / min, the heating temperature can be 300℃, 400℃, 450℃, and the holding time can be 2 hours, 3 hours, 5 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. After the holding time is completed, the mixture is naturally cooled to obtain the secondary sintered sample. The particle size of the lithium-rich manganese-based material is 5-10μm, for example, it can be 5μm, 7μm, 10μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, in step S1, the nickel source includes one or more combinations of nickel chloride, nickel sulfate, nickel nitrate, nickel bromide, and nickel aminosulfonate; the manganese source includes one or more combinations of manganese chloride, manganese sulfate, manganese nitrate, manganese bromide, and manganese aminosulfonate; the titanium source includes one or more combinations of titanium sulfate, titanium oxysulfate, titanium nitrate, and titanium oxalate; the molybdenum source includes one or more combinations of sodium molybdate, potassium molybdate, and ammonium molybdate; the precipitant includes one or more combinations of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide solution; and the complexing agent includes ammonia and oxalic acid, or a combination thereof.

[0029] Preferably, the titanium source and molybdenum source also include titanium and molybdenum complexes, wherein the titanium and molybdenum complexes include at least one of salicylate-imine-molybdenum-titanium complex, pyridine-imine-molybdenum-titanium complex, and symmetrical amine-fluorene-dimethyl-molybdenum-titanium complex.

[0030] Preferably, in step S2, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium chloride, lithium sulfate, lithium nitrate, and lithium oxalate.

[0031] Secondly, this application provides a lithium-rich manganese-based material, which adopts the following technical solution:

[0032] A lithium-rich manganese-based material, wherein the lithium-rich manganese-based material is prepared by the method described above.

[0033] Thirdly, this application provides a lithium-ion battery, which adopts the following technical solution:

[0034] A lithium-ion battery includes a positive electrode and a negative electrode. The positive electrode includes a current collector and a positive electrode active material layer formed by a positive electrode active slurry, wherein the positive electrode active slurry includes a lithium-rich manganese-based material as described above.

[0035] Preferably, the positive electrode slurry includes the lithium-rich manganese substrate, SP, PVDF, and CNT, and the mass ratio of the lithium-rich manganese substrate, SP, PVDF, and CNT is 92:5-t:3-t:2t, 0≤t≤1. For example, it can be 0.1, 0.3, 0.5, 0.8, or 1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Attached Figure Description

[0036] Figure 1 This is a SEM scan of the precursor (A) and the lithium-rich manganese-based material (B) in Example 1 of this application.

[0037] Figure 2 This is a resistivity test diagram of the lithium-rich manganese-based material in Example 1 of this application.

[0038] Figure 3 This is an EIS test image of the lithium-ion battery in Example 1 of this application.

[0039] Figure 4 The graphs show the high-temperature cycling performance of the lithium-ion batteries in Example 1 and Comparative Example 1 of this application.

[0040] Figure 5 The graphs show the high-temperature storage performance of the lithium-ion batteries in Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0041] To better understand and implement this invention, the technical solution of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0043] Unless otherwise stated, all numerical values ​​for the amounts of expressed components, reaction conditions, etc., used in the specification and claims are to be understood as being modified by the term "about". Therefore, unless otherwise indicated, the numerical parameters set forth herein are approximate values ​​that can be varied to obtain the desired performance.

[0044] The word “and / or” as used in this article refers to one or all of the elements mentioned.

[0045] The terms "include" and "contain" as used in this article cover both cases where only the mentioned elements exist and cases where there are other unmentioned elements in addition to the mentioned elements.

[0046] All percentages in this invention are by weight and their general chemical formulas are , unless otherwise stated.

[0047] Unless otherwise stated, the terms “a,” “an,” “an,” and “the” as used in this specification are intended to include “at least one” or “one or more.” For example, “a component” refers to one or more components, and therefore more than one component may be considered and may be employed or used in the implementation of the described embodiments.

[0048] Example

[0049] Example 1

[0050] 1. Preparation of lithium-rich manganese-based materials

[0051] A lithium-rich manganese-based material with the chemical formula Li 1.3 Ni 0.35 Mn 0.65 Ti 0.008 Mo 0.06 O2;

[0052] Solution preparation:

[0053] Metal salt solution A: Weigh nickel sulfate and manganese sulfate in a stoichiometric ratio of 0.35:0.65, dissolve them in water, and prepare a metal salt solution A with a total concentration of 3 mol / L;

[0054] Metal salt solution B: Weigh titanium oxalate and ammonium molybdate according to a stoichiometric ratio of 0.008:0.06, dissolve them in water, and prepare a metal salt solution B with a total concentration of 0.05 mol / L;

[0055] The precipitant was a sodium hydroxide solution with a concentration of 2 mol / L; the complexing agent was ammonia water with a concentration of 1 mol / L.

[0056] Its preparation method is as follows:

[0057] S1: Add the above metal salt solution A to the reaction vessel at a speed of 5 mL / min and a rotation speed of 60 rpm and control the temperature at 50℃. Then add the above metal salt solution B dropwise to the reaction vessel at a speed of 4 mL / min. Adjust the pH value of the reaction system to 8.5 and the temperature to 50℃ to obtain metal salt solution C.

[0058] The above-mentioned precipitant and complexing agent were added dropwise to the above-mentioned metal salt solution C at a rate of 2 mL / min, and the pH value of the reaction system was adjusted to 10 to obtain a mixed salt solution.

[0059] The temperature of the above mixed salt solution was lowered to -10℃ and stirred at 120 rpm for 90 min, then stirred at 100 rpm at 45℃, and then reacted at a constant temperature for 90 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor.

[0060] S2: The lithium source and the precursor obtained in S1 are mixed and ground at a molar ratio of 1.3:1 to obtain the first mixed powder; the first mixed powder is placed in an oxygen-containing inert atmosphere (oxygen concentration 95%), heated to 500℃ at a heating rate of 10℃ / min, held at the temperature for 8h, then heated to 820℃ at a heating rate of 15℃, held at the temperature for 5h, and then naturally cooled after the holding time is completed to obtain a first sintered sample;

[0061] The first sintered sample was ball-milled to a second mixed powder with a particle size of 1-10 μm. The second mixed powder was placed in an oxygen-containing inert atmosphere (oxygen concentration 99%) and heated to 350°C at a heating rate of 5°C / min. The temperature was held for 5 hours and then naturally cooled to obtain the second sintered sample.

[0062] The secondary sintered sample was ball-milled to a particle size of 5-10 μm and then sieved to obtain the lithium-rich manganese-based material.

[0063] The SEM detection results of the lithium-rich manganese-based material prepared in this embodiment are as follows: Figure 1 As shown in Table 1, the specific surface area, particle size distribution, and particle size D50 of the precursor and the lithium-rich manganese-based material in this embodiment are shown in Table 1. The powder resistivity test results of the lithium-rich manganese-based material in this embodiment are shown in Table 1. Figure 2 As shown. The EIS test results of the lithium battery in this embodiment are as follows. Figure 3 As shown. The high-temperature cycle performance test results of the lithium battery in this embodiment are as follows. Figure 4 As shown. The high-temperature storage performance test results of the lithium battery in this embodiment are as follows. Figure 5 As shown.

[0064] 2. Preparation of positive electrode sheet

[0065] The positive electrode slurry was prepared as follows: lithium-rich manganese-based material, conductive carbon black SP, and PVDF carbon nanotube binder were added to a vacuum mixer at a mass ratio of 92:5-t:3-t:2t, 0≤t≤1 for mixing. Then, solvent NMP was added to the mixed slurry, and the mixture was stirred until homogeneous under vacuum, thus obtaining the positive electrode slurry of this embodiment. The above positive electrode slurry was uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. After drying in the oven, a semi-finished positive electrode sheet was obtained. The semi-finished positive electrode sheet was then cold-pressed and slit to obtain the positive electrode sheet to be assembled.

[0066] 3. Preparation of negative electrode sheet

[0067] The negative electrode slurry was prepared as follows: Artificial graphite, conductive agent acetylene black, thickener CMC, and binder SBR were added to a vacuum mixer at a mass ratio of 96.4:1:1.2:1.4 and mixed. Deionized water was then added to the resulting mixture, and the mixture was stirred under vacuum until homogeneous, thus obtaining the negative electrode slurry of this embodiment. The negative electrode slurry was uniformly coated onto both surfaces of the negative electrode current collector copper foil. After air-drying at room temperature, it was transferred to an oven for further drying. After drying in the oven, a semi-finished negative electrode sheet was obtained. The semi-finished negative electrode sheet was then cold-pressed and slit to obtain the negative electrode sheet to be assembled.

[0068] 4. Lithium-ion battery assembly

[0069] Commercially available polyethylene film is used as the separator for the lithium-ion battery, and a commercially available electrolyte suitable for 4.2V (upper charging voltage) battery system is used as the electrolyte. The above-mentioned positive electrode sheet, negative electrode sheet and separator are wound together to obtain bare cell. The bare cell is then packaged, injected with electrolyte, left to stand, formed and tested for capacity to obtain the finished battery.

[0070] Example 2

[0071] 1. Preparation of lithium-rich manganese-based materials

[0072] A lithium-rich manganese-based material with the chemical formula Li 1.3 Ni 0.2 Mn 0.8 Ti 0.001 Mo 0.01 O2;

[0073] Solution preparation:

[0074] Metal salt solution A: Weigh nickel chloride and manganese chloride in a stoichiometric ratio of 0.2:0.8, dissolve them in water, and prepare a metal salt solution A with a total concentration of 1 mol / L;

[0075] Metal salt solution B: Weigh titanium sulfate and sodium molybdate in a stoichiometric ratio of 0.001:0.01, dissolve them in water, and prepare a metal salt solution B with a total concentration of 0.01 mol / L.

[0076] The precipitant is sodium hydroxide solution with a concentration of 1 mol / L; the complexing agent is ammonia water with a concentration of 0.5 mol / L.

[0077] Its preparation method is as follows:

[0078] S1: Add the above metal salt solution A to the reaction vessel at a speed of 10 mL / min and a rotation speed of 50 rpm and control the temperature at 70 °C. Then add the above metal salt solution B dropwise to the reaction vessel at a speed of 10 mL / min. Adjust the pH value of the reaction system to 8 and the temperature to 60 °C to obtain metal salt solution C.

[0079] The above-mentioned precipitant and complexing agent were added dropwise to the above-mentioned metal salt solution C at a rate of 10 mL / min, and the pH value of the reaction system was adjusted to 11 to obtain a mixed salt solution.

[0080] The temperature of the above mixed salt solution was lowered to 0°C and stirred at 150 rpm for 60 min, then stirred at 50 rpm at 60°C, and then reacted at a constant temperature for 60 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor.

[0081] S2: The lithium source and the precursor obtained in S1 are mixed and ground at a molar ratio of 1.4:1 to obtain the first mixed powder; the first mixed powder is placed in an oxygen-containing inert atmosphere (oxygen concentration 80%), heated to 550℃ at a heating rate of 5℃ / min, held at the temperature for 5h, then heated to 900℃ at a heating rate of 30℃, held at the temperature for 10h, and then naturally cooled after the holding time is completed to obtain a first sintered sample;

[0082] The first sintered sample was ball-milled to a second mixed powder with a particle size of 1-10 μm. The second mixed powder was placed in an oxygen-containing inert atmosphere (oxygen concentration 80%) and heated to 450°C at a heating rate of 10°C / min. The temperature was held for 2 hours and then naturally cooled to obtain the second sintered sample.

[0083] The secondary sintered sample was ball-milled to a particle size of 5-10 μm and then sieved to obtain the lithium-rich manganese-based material.

[0084] The rest of the parts are consistent with Example 1.

[0085] Example 3

[0086] 1. Preparation of lithium-rich manganese-based materials

[0087] A lithium-rich manganese-based material with the chemical formula Li 1.3 Ni 0.4 Mn 0.5 Ti 0.01 Mo 0.1 O2;

[0088] Solution preparation:

[0089] Metal salt solution A: Weigh nickel nitrate and manganese nitrate in a stoichiometric ratio of 0.4:0.5, dissolve them in water, and prepare a metal salt solution A with a total concentration of 5 mol / L;

[0090] Metal salt solution B: Weigh titanium nitrate and potassium molybdate in a stoichiometric ratio of 0.01:0.1, dissolve them in water, and prepare a metal salt solution B with a total concentration of 0.1 mol / L;

[0091] The precipitant was a sodium hydroxide solution with a concentration of 10 mol / L; the complexing agent was ammonia water with a concentration of 5 mol / L.

[0092] Its preparation method is as follows:

[0093] S1: Add the above metal salt solution A to the reaction vessel at a speed of 8 mL / min and a rotation speed of 80 rpm and control the temperature at 40℃. Then add the above metal salt solution B dropwise to the reaction vessel at a speed of 7 mL / min. Adjust the pH value of the reaction system to 9 and the temperature to 55℃ to obtain metal salt solution C.

[0094] The above-mentioned precipitant and complexing agent were added dropwise to the above-mentioned metal salt solution C at a rate of 7 mL / min, and the pH value of the reaction system was adjusted to 9 to obtain a mixed salt solution.

[0095] The temperature of the above mixed salt solution was lowered to -5℃ and stirred at 100 rpm for 80 min, then stirred at 80 rpm at 50℃, and then reacted at a constant temperature for 70 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor.

[0096] S2: The lithium source and the precursor obtained in S1 are mixed and ground at a molar ratio of 1.1:1 to obtain the first mixed powder; the first mixed powder is placed in an oxygen-containing inert atmosphere (oxygen concentration 90%), heated to 520°C at a heating rate of 8°C / min, held at the temperature for 7 hours, then heated to 800°C at a heating rate of 20°C, held at the temperature for 8 hours, and then naturally cooled after the holding time is completed to obtain a first sintered sample;

[0097] The first sintered sample was ball-milled to a second mixed powder with a particle size of 1-10 μm. The second mixed powder was placed in an oxygen-containing inert atmosphere (oxygen concentration 95%) and heated to 400°C at a heating rate of 7°C / min. The temperature was held for 3 hours and then naturally cooled to obtain the second sintered sample.

[0098] The secondary sintered sample was ball-milled to a particle size of 5-10 μm and then sieved to obtain the lithium-rich manganese-based material.

[0099] The rest of the parts are consistent with Example 1.

[0100] Example 4

[0101] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the lithium-rich manganese-based material, S1 adopts the following steps:

[0102] S1: Add the above metal salt solution A to the reaction vessel at a speed of 5 mL / min and a rotation speed of 60 rpm and control the temperature at 50℃. Then add the above metal salt solution B directly to the reaction vessel, adjust the pH value of the reaction system to 8.5 and the temperature to 50℃ to obtain metal salt solution C.

[0103] The above-mentioned precipitant and complexing agent were directly added to the above-mentioned metal salt solution C, and the pH value of the reaction system was adjusted to 10 to obtain a mixed salt solution.

[0104] The temperature of the above mixed salt solution was lowered to -10°C and stirred at 120 rpm for 90 min, then stirred at 100 rpm at 45°C, and then reacted at a constant temperature for 90 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor; the rest of the product was consistent with that in Example 1.

[0105] Example 5

[0106] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the lithium-rich manganese-based material, S1 adopts the following steps:

[0107] S1: Add the above metal salt solution A to the reaction vessel at a speed of 2 mL / min and a rotation speed of 100 rpm and control the temperature at 80℃. Then add the above metal salt solution B dropwise to the reaction vessel at a speed of 2 mL / min. Adjust the pH value of the reaction system to 8.5 and the temperature to 70℃ to obtain metal salt solution C.

[0108] The above-mentioned precipitant and complexing agent were added dropwise to the above-mentioned metal salt solution C at a rate of 1 mL / min, and the pH value of the reaction system was adjusted to 10 to obtain a mixed salt solution.

[0109] The temperature of the above mixed salt solution was lowered to -10℃ and stirred at 100 rpm for 50 min, then stirred at 120 rpm at 45℃, and then reacted at a constant temperature for 50 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor.

[0110] Example 6

[0111] The difference between this embodiment and Embodiment 1 is that step S2 in the preparation process of the lithium-rich manganese-based material adopts the following steps:

[0112] S2: The lithium source and the precursor obtained in S1 are mixed and ground at a molar ratio of 1.3:1 to obtain the first mixed powder; the first mixed powder is placed in an oxygen-containing inert atmosphere (oxygen concentration 99%), heated to 500℃ at a heating rate of 10℃ / min, held at the temperature for 15h, then heated to 820℃ at a heating rate of 15℃, held at the temperature for 5h, and then naturally cooled after the holding time is completed to obtain a first sintered sample;

[0113] The sintered sample was ball-milled to a particle size of 5-10 μm, sieved, and the lithium-rich manganese-based material was obtained. The remaining steps were consistent with Example 1.

[0114] Example 7

[0115] The difference between this embodiment and Example 1 is that metal salt solution B is prepared using salicylic acid imine molybdenum titanium complex and pyridine imine molybdenum titanium complex;

[0116] The temperature change operation in S1 follows these steps:

[0117] The above mixed salt solution was frozen at -55°C and 30 Pa for 24 h, and then dried at 50°C and 100 Pa for 24 h to obtain the precursor.

[0118] Comparative Example 1

[0119] The difference between this comparative example and Example 1 is that no titanium source or molybdenum source is used in the preparation of the lithium-rich manganese-based material, and the mixed salt solution is not subjected to temperature changes during the preparation process. The specific preparation steps are as follows:

[0120] S1: The above metal salt solution B is added dropwise to the reaction vessel at a rate of 4 mL / min. The pH value of the reaction system is adjusted to 8.5 and the temperature is adjusted to 50℃ to obtain metal salt solution C.

[0121] The above-mentioned precipitant and complexing agent were added dropwise to the above-mentioned metal salt solution C at a rate of 2 mL / min, and the pH value of the reaction system was adjusted to 10 to obtain a mixed salt solution.

[0122] The above mixed salt solution was stirred at 100 rpm at 45°C, and then reacted at a constant temperature for 180 min. The resulting product was subjected to solid-liquid separation and drying to obtain the precursor. The rest of the process was consistent with Example 1.

[0123] The specific surface area, particle size distribution, and particle size D50 of the precursor and lithium-rich manganese-based material in this comparative example are shown in Table 1. The powder resistivity test results of the lithium-rich manganese-based material in this comparative example are as follows: Figure 2 As shown. The EIS test results of the lithium battery in this comparative example are as follows. Figure 3 As shown in the figure. The high-temperature cycle performance test results of the lithium battery in this comparative example are as follows. Figure 4 As shown in the figure. The high-temperature storage performance test results of the lithium battery in this comparative example are as follows. Figure 5 As shown.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is that the chemical formula of the lithium-rich manganese-based material is Li. 1.2 Mn 0.6 Ni 0.2 The preparation of O2 / C involves the following steps:

[0126] (1) Prepare a mixed solution of manganese chloride and nickel chloride with a total metal ion concentration of 1 mol / L, i.e., a metal solution, according to the Mn / Ni molar ratio of 3;

[0127] (2) Nitrogen gas is introduced into the above metal solution environment to purge the air in the reactor and nitrogen gas is continuously introduced; then, 2 mol / L NaOH solution is used as a precipitant, and the above metal solution, precipitant and ammonia complexing agent are added to the reactor in parallel to carry out the precipitation reaction. During the reaction, the reaction temperature is maintained at 60℃, the stirring speed is 30 r / min, and the pH of the reaction system is maintained at 10-12. After all the reactants are added, the mixture is aged to obtain the coprecipitated product.

[0128] (3) The coprecipitated product was washed, filtered, and then dried under vacuum at 120°C to obtain the precursor;

[0129] (4) The precursor was prepared by adding lithium hydroxide and glucose in a lithium / manganese / carbon molar ratio of 1.05:1:0.8, ball milling for 2 hours, and then synthesizing in air at a high temperature of 800-950℃ for 12 hours to obtain lithium-rich manganese-based material.

[0130] The rest of the parts are consistent with Example 1.

[0131] Comparative Example 3

[0132] The difference between this comparative example and Example 1 is that an equal weight of zirconium source is used instead of titanium source and an equal weight of tungsten source is used instead of molybdenum source in the preparation process of lithium-rich manganese-based material. All other parts are consistent with Example 1.

[0133] Comparative Example 4

[0134] The difference between this comparative example and Example 1 is that, in the preparation process of the lithium-rich manganese-based material, the mixed salt solution in S1 is not subjected to temperature change treatment, but is directly stirred at 100 rpm at 45°C, and then reacted at a constant temperature for 90 min. The resulting product is then subjected to solid-liquid separation and drying to obtain the precursor.

[0135] Comparative Example 5

[0136] The difference between this comparative example and Example 1 is that, in the preparation process of the lithium-rich manganese-based material, the mixed salt solution in S1 was cooled to 2°C and stirred at 120 rpm for 90 min, then stirred at 100 rpm at 65°C, followed by a constant temperature reaction for 90 min. The resulting product was then subjected to solid-liquid separation and drying to obtain the precursor. The rest of the process remained the same as in Example 1.

[0137] Test methods

[0138] I. SEM Testing

[0139] The precursor and lithium-rich manganese-based material prepared in Example 1 were subjected to SEM tests to observe their morphology.

[0140] II. Specific Surface Area Test

[0141] The specific surface area of ​​the precursor and lithium-rich manganese-based material prepared in Example 1 was tested using a specific surface area meter.

[0142] III. Particle Size Testing

[0143] The particle size of the precursor and lithium-rich manganese-based material prepared in Example 1 was tested using a laser particle size analyzer.

[0144] IV. Powder Resistivity Testing

[0145] The precursors and lithium-rich manganese-based materials in the above embodiments and comparative examples were subjected to powder resistivity tests. The specific test steps are as follows: The powder resistivity test conditions are 5-195 MPa, and the test is performed once every 10 MPa. The test result is the powder resistivity corresponding to 195 MPa.

[0146] V. EIS Testing

[0147] The lithium-ion batteries in the above embodiments and comparative examples were subjected to EIS testing, and the EIS testing conditions were: fi = 500 kHz, ff = 10 MHz, Nd = 10.

[0148] VI. High-Temperature Cyclic Performance Test

[0149] The lithium batteries in the above embodiments and comparative examples were subjected to a 45°C high-temperature cycling test. The conditions for the high-temperature cycling test were: test voltage of 2.0-4.55V, charge and discharge rate of 1C, and the cycle capacity retention rate and DCR value of the lithium batteries after 500 cycles were recorded.

[0150] VII. High-Temperature Storage Performance Test

[0151] The lithium batteries in the above embodiments and comparative examples were subjected to high-temperature storage performance tests. The test voltage was 2.0-4.55V, the cell state was 100% SOC, and the charge / discharge rate was 1C. The batteries were removed from the storage chamber on the 5th, 10th, 15th, 25th, and 35th days of storage. The capacity recovery rate and DCR growth rate were calculated on the 35th day of storage.

[0152] Table 1

[0153]

[0154] Table 2

[0155]

[0156]

[0157] Based on Examples 1-3, Comparative Examples 1-5, and Table 1-2, it can be seen that compared to Example 1, the powder resistivity of the comparative examples is significantly increased, the EIS value of the lithium battery increases, and the high-temperature cycling performance and high-temperature storage performance both decrease. This is because, in this application, a precursor is prepared using a salt solution, allowing titanium and molybdenum sources to be doped into the precursor at the atomic level, achieving uniform coating of the precursor. Furthermore, the use of a variable-temperature process—first cooling to below 0°C and then heating to above 0°C—in the precursor preparation process forms a loose and porous structure. This structure, combined with the uniformly doped titanium and molybdenum, significantly reduces the powder resistivity of the lithium-rich manganese-based new material, significantly reducing the impedance growth of the lithium battery during high-temperature cycling and high-temperature storage. This, in turn, significantly improves the capacity retention rate during high-temperature cycling and the capacity recovery rate during high-temperature storage of the lithium-ion battery, contributing to the improvement of the lithium battery's cycle performance and high-temperature performance.

[0158] Based on Examples 1, 4-5 and Table 1-2, it can be seen that when metal salt solution B, precipitant and complexing agent are directly added to the reaction system or the stirring state during the reaction process is changed, the resistivity of the lithium-rich manganese-based material powder prepared in the end increases slightly, and the high-temperature cycle performance and high-temperature storage performance of the lithium battery decrease. This is because the raw material addition process of this application helps the raw materials to react fully and achieve uniform doping of titanium and molybdenum.

[0159] Based on Examples 1 and 6 and Tables 1-2, it can be seen that when the precursor and lithium source are sintered in one step, the resistivity of the final lithium-rich manganese-based material powder increases slightly. This is because the coating of the lithium source and precursor is uneven due to the one-step sintering, which will affect the particle size distribution of the lithium-rich manganese-based material powder and is not conducive to the decrease of the resistivity of the lithium-rich manganese-based material powder.

[0160] Based on Examples 1 and 7 and Tables 1-2, it can be seen that when zirconium and tungsten are used to dop the lithium-rich manganese-based material, the specific surface area of ​​the final lithium-rich manganese-based material decreases and the powder resistivity increases, resulting in an increase in the impedance of the lithium battery and a decrease in high-temperature cycle performance and high-temperature storage performance. This is because, compared with zirconium and tungsten doping, titanium and molybdenum doping in lithium-rich manganese-based materials is more uniform, and the loose porous structure of the lithium-rich manganese-based material doped with titanium and molybdenum is more uniform after temperature operation.

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention, but such modifications or substitutions are all within the scope of protection of the present invention.

Claims

1. A method for preparing lithium-rich manganese-based materials, characterized in that: The general chemical formula of the lithium-rich manganese-based material is Li. n Ni x Mn y Ti a Mo b O2, where 1.0 < n < 1.5, 0.2 < x < 0.4, 0.5 < y < 0.8, 0.001 < a < 0.01, 0.01 < b < 0.1; The preparation method includes the following steps: S1: Dissolve nickel source and manganese source in water to obtain metal salt solution A, dissolve titanium source and molybdenum source in water to obtain metal salt solution B, mix metal salt solution B with metal salt solution A to obtain metal salt solution C, mix metal salt solution C with precipitant and complexing agent to obtain mixed salt solution, and then perform temperature-controlled operation, followed by solid-liquid separation and drying to obtain precursor; S2: The precursor obtained in S1 is mixed with a lithium source, ground, and calcined to obtain the lithium-rich manganese-based material; The temperature change operation in S1 includes the following steps: cooling the mixed salt solution to below 0°C and then heating it to above 0°C; S1 includes: stirring the metal salt solution A, then adding the metal salt solution B dropwise to the metal salt solution A, adjusting the pH and temperature of the reaction system to obtain the metal salt solution C; the dropping rate of the metal salt solution B is 4-10 mL / min, and the pH of the reaction system is adjusted to 8-9 and the reaction temperature is 50-60℃ before obtaining the metal salt solution C; the metal salt solution B is prepared by weighing titanium source and molybdenum source according to the stoichiometric ratio a:b and dissolving them in water, and the concentration of the metal salt solution B is 0.01-0.1 mol / L; the precursor includes at least one of MCO3 and M(OH)2, wherein M represents Ni, Mn, Ti and Mo.

2. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: S1 includes: sequentially adding the precipitant and the complexing agent to the metal salt solution C, adjusting the pH value of the reaction system, and obtaining the mixed salt solution; The temperature-changing operation includes the following steps: first, cooling the mixed salt solution to -10℃ to 0℃ and stirring at 100-150 rpm for 60-90 min, then heating it to 45-60℃ and stirring at 50-100 rpm, and after the heating is completed, holding it at 45-60℃ for 60-90 min; or, freezing the mixed salt solution in an environment of -50℃ to -60℃ and a vacuum degree of 20-40 Pa for 22-26 h, and then drying it in an environment of 45-60℃ and a vacuum degree of 95-105 Pa for 22-26 h to obtain the precursor.

3. The method for preparing a lithium-rich manganese-based material according to claim 2, characterized in that: The metal salt solution A was stirred at 50-80 rpm at 40-70°C. The dropping rate of both the precipitant and the complexing agent is 2-10 mL / min, and the pH of the reaction system is adjusted to 9-11 before obtaining the mixed salt solution.

4. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: According to the stoichiometric ratio x:y, nickel source and manganese source are weighed and dissolved in water to prepare the metal salt solution A, the concentration of the metal salt solution A is 0.5-5 mol / L; The concentration of the precipitant is 1-10 mol / L; The concentration of the complexing agent is 0.5-5 mol / L.

5. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: In step S1, the precursor has a particle size D50 of 5-10 μm, a particle size distribution satisfying 0.3 ≤ (D90-D10) / D50 ≤ 0.8, and a specific surface area of ​​15-40 m². 2 / g.

6. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: In step S2, the molar ratio of the lithium source to the precursor is 1.1-1.4:

1.

7. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: S2 includes: mixing the precursor with the lithium source and grinding them to obtain a first mixed powder; sintering the first mixed powder once to obtain a first sintered sample; pulverizing the first sintered sample to obtain a second mixed powder; sintering the second mixed powder a second time to obtain a second sintered sample; and pulverizing the second sintered sample to obtain the lithium-rich manganese-based material.

8. The method for preparing a lithium-rich manganese-based material according to claim 7, characterized in that: The first sintering is carried out in an oxygen-containing inert atmosphere. During the first sintering process, the first mixed powder is first heated to 500-550℃ at a heating rate of 5-10℃ / min and held at that temperature for 5-10h. Then, it is heated to 800-900℃ at a heating rate of 15-30℃ and held at that temperature for 5-10h. After the holding temperature is completed, it is naturally cooled to obtain the first sintered sample. The secondary sintering is carried out in an oxygen-containing inert atmosphere. During the secondary sintering process, the second mixed powder is first heated to 300-450℃ at a heating rate of 5-10℃ / min, held at the temperature for 2-5 hours, and then naturally cooled after the holding time is completed to obtain the secondary sintered sample.

9. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: In S1, the nickel source includes one or more combinations of nickel chloride, nickel sulfate, nickel nitrate, nickel bromide, and nickel aminosulfonate. The manganese source includes one or more combinations of manganese chloride, manganese sulfate, manganese nitrate, manganese bromide, and manganese aminosulfonate. The titanium source includes one or more combinations of titanium sulfate, titanium oxysulfate, titanium nitrate, and titanium oxalate. The molybdenum source includes one or more combinations of sodium molybdate, potassium molybdate, and ammonium molybdate; The precipitant includes one or more combinations of sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium hydroxide, and potassium hydroxide solution. The complexing agent includes one or a combination of ammonia, oxalic acid, or other similar substances.

10. The method for preparing a lithium-rich manganese-based material according to claim 1, characterized in that: In step S2, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium chloride, lithium sulfate, lithium nitrate, and lithium oxalate.

11. A lithium-rich manganese-based material, characterized in that: The lithium-rich manganese-based material is prepared by the method described in any one of claims 1-10.

12. A lithium-ion battery, characterized in that: It includes a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet includes a current collector and a positive electrode active material layer formed by a positive electrode active slurry, and the positive electrode active slurry includes the lithium-rich manganese-based material as described in claim 11.

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