Lithium-rich manganese-based positive electrode material and preparation method and application thereof

Abstract

The invention provides a lithium-rich manganese-based positive electrode material as well as a preparation method and application thereof, and relates to the technical field of solid-state batteries. Specifically, the molecular formula of the lithium-rich manganese-based positive electrode material is Li Mn N < c > Co < d > Fe < e > Cu < f > Zn < g > La < h > Al Mg < j > O < 2 >, the preparation method comprises the following steps: preparing metal salts corresponding to metal elements in the lithium-rich manganese-based positive electrode material, and mixing and dissolving the metal salts in a solvent to obtain a dispersion liquid; then, citric acid is added into the dispersion liquid, then the pH is adjusted to 7.5-8.5, aging treatment, drying treatment, first sintering treatment, second sintering treatment and quenching treatment are sequentially conducted, and the lithium-rich manganese-based positive electrode material is obtained. According to the local high-entropy manganese-based lithium-rich positive electrode provided by the invention, through a multi-component doping strategy, the stress change of a positive electrode material in an electrochemical process is reduced, the cycle performance of a solid-state battery is enhanced, the voltage attenuation is reduced, and the local high-entropy manganese-based lithium-rich positive electrode has a good application prospect.

Description

Technical Field

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

[0002] Lithium-ion batteries have garnered significant attention in modern energy technology due to their simple and efficient energy storage characteristics. However, traditional liquid batteries face issues of toxicity and flammability due to the use of organic electrolytes. Furthermore, lithium dendrites penetrating the separator can cause internal short circuits, posing safety hazards. To improve safety and achieve higher-performance and lower-cost energy storage systems, developing solid-state batteries to replace the electrolytes and separators in traditional liquid batteries has become a crucial issue in the current energy field.

[0003] Compared to commercially available materials such as lithium cobalt oxide, ternary materials, and lithium iron phosphate, lithium-rich manganese-based materials offer higher specific capacity due to their unique anion redox mechanism, making them considered the most promising cathode materials for high-energy-density batteries. However, the high manganese content in lithium-rich manganese-based materials results in significantly lower electronic conductivity compared to lithium cobalt oxide and ternary materials. Therefore, when used as cathode materials in all-solid-state batteries, a large amount of conductive additives is needed to compensate for their insufficient electronic conductivity. Electronic conductivity is particularly important under high-rate operating conditions requiring rapid charge and discharge. However, the composite electrode formed by the cathode and solid electrolyte in all-solid-state batteries is highly sensitive to side reactions of conductive additives; therefore, improving the electronic conductivity of lithium-rich materials as electrodes is equally crucial.

[0004] Furthermore, solid-state electrolytes generally suffer from a narrow voltage window. When charged to higher voltages, the electrolyte is prone to decomposition, making it difficult to match the charge / discharge voltage range required by the cathode material. This is especially true for lithium-rich materials, which require a voltage range of 4.8V (vs. Li / Li). + Operating the battery at low capacity to fully utilize its capacity can lead to severe interfacial side reactions during charging and discharging. These side reaction products typically form phases that significantly hinder ion transport, severely impacting the overall polarization of the battery and the capacity utilization of the cathode material.

[0005] Finally, due to the unique anionic redox mechanism of lithium-rich materials, significant oxygen loss occurs during charge and discharge, leading to gradual degradation of the material structure. Furthermore, the lost oxygen readily reacts with the solid electrolyte at the interface, further exacerbating the decline in interfacial ion transport capacity. The unique redox mechanism in lithium-rich materials results in severe voltage decay and capacity degradation, problems that persist even in all-solid-state batteries.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a lithium-rich manganese-based cathode material, primarily used as the cathode active material for all-solid-state batteries, to address the current problems of insufficient electronic conductivity, side reactions caused by high-conductivity agents, low content of active materials, severe interfacial side reactions, oxygen loss during charging and discharging, and the technical defects of macroscopic voltage decay and capacity degradation in solid-state batteries caused by the aforementioned problems.

[0008] The second objective of this invention is to provide a method for preparing the lithium-rich manganese-based cathode material described above.

[0009] A third objective of this invention is to provide a solid-state battery.

[0010] The fourth objective of this invention is to provide an electrical device.

[0011] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A lithium-rich manganese-based cathode material with the molecular formula Li a Mn b Ni c Co d Fe e Cu f Zn g La h Al i Mg j O2; 1 < a ≤ 1.2, 0.4 < b ≤ 0.55, 0.1 < c ≤ 0.25, 0 ≤ d ≤ 0.1, 0 < e ≤ 0.02, 0 < f ≤ 0.02, 0 < g ≤ 0.02, 0 < h ≤ 0.02, 0 < i ≤ 0.02, 0 < j ≤ 0.02.

[0012] A method for preparing the lithium-rich manganese-based cathode material includes the following steps: (1) Prepare the metal salts corresponding to the metal elements in the lithium-rich manganese-based cathode material, mix and dissolve them in a solvent to obtain a dispersion; (2) Add citric acid to the dispersion, and then adjust the pH to 7.5~8.5. Then perform aging treatment, drying treatment, first sintering treatment, second sintering treatment and quenching treatment in sequence to obtain the lithium-rich manganese-based cathode material.

[0013] Preferably, the molar ratio of citric acid to lithium salt in the metal salt is (1.8~2.5):1.

[0014] Preferably, the aging treatment temperature is 70℃~85℃, and the aging treatment time is 5h~15h.

[0015] Preferably, the drying temperature is 110℃~140℃.

[0016] Preferably, the temperature of the first sintering treatment is 400℃~500℃, and the time of the first sintering treatment is 1.5h~5h.

[0017] Preferably, the temperature of the second sintering treatment is 800℃~1000℃, and the time of the second sintering treatment is 8h~15h.

[0018] Preferably, before the first sintering treatment and after the drying treatment, a grinding treatment is further included.

[0019] Preferably, the process further includes a tableting process after the first sintering treatment and before the second sintering treatment.

[0020] A solid-state battery, wherein the positive electrode comprises the aforementioned lithium-rich manganese-based positive electrode material.

[0021] An electrical device comprising the aforementioned solid-state battery.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a lithium-rich manganese-based cathode material for solid-state batteries and its preparation method. Utilizing a multi-component doping strategy, it synergistically integrates the advantages of multiple doping elements, stabilizing oxygen in the crystal structure and forming a locally high-entropy lithium-rich manganese-based cathode. Unlike traditional high-entropy materials, the locally high-entropy of this invention does not require the material as a whole to reach a high-entropy state. Instead, it artificially designs or naturally forms a local environment with high mixing entropy characteristics (high mixing of multiple elements) in specific micro-regions. Furthermore, the locally high-entropy lithium-rich manganese-based cathode avoids damage to the Li2MnO3 phase and reduces stress changes in the cathode material during electrochemical processes through the high-entropy effect. This solves the problem of solid-solid contact failure in solid-state battery cathode materials, enabling the lithium-rich manganese-based cathode to achieve excellent cycle performance in all-solid-state batteries and reducing voltage decay. Attached Figure Description

[0023] 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.

[0024] Figure 1 XRD comparison diagrams of Embodiment 1 and the comparative example of the present invention are provided; Figure 2 A comparison chart of the cycle performance of all-solid-state batteries in Embodiment 1 of the present invention and a comparative example is provided; Figure 3 The constant current charge-discharge curve of the all-solid-state battery in Embodiment 1 of the present invention is provided; Figure 4 The present invention provides a comparative example of the constant current charge-discharge curve of an all-solid-state battery. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not 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 of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] The first aspect of the present invention is to provide a lithium-rich manganese-based cathode material.

[0027] The molecular formula of the lithium-rich manganese-based cathode material is Li. a Mn b Ni c Co d Fe e Cu f Zn g La h Al i Mg j O2; and satisfying: 1 < a ≤ 1.2, 0.4 < b ≤ 0.55, 0.1 < c ≤ 0.25, 0 ≤ d ≤ 0.1, 0 < e ≤ 0.02, 0 < f ≤ 0.02, 0 < g ≤ 0.02, 0 < h ≤ 0.02, 0 < i ≤ 0.02, 0 < j ≤ 0.02.

[0028] The lithium-rich manganese-based cathode material described in this invention can be cobalt-free or cobalt-containing. Those skilled in the art can make adaptive choices regarding the addition of cobalt based on the performance requirements of the lithium-rich manganese-based cathode material.

[0029] As an optional implementation, the values ​​of a~j include, but are not limited to, any one of the following values, or any range of two values: a 1.01, 1.03, 1.05, 1.08, 1.10, 1.12, 1.15, 1.18, 1.2; b 0.41, 0.42, 0.45, 0.48, 0.50, 0.52, 0.54, 0.55; c 0.11, 0.12, 0.15, 0.18, 0.2, 0.22, 0.24, 0.25; d 0, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1; e~j 0.001, 0.005, 0.008, 0.01, 0.012, 0.014, 0.015, 0.016, 0.018, 0.02.

[0030] A second aspect of the present invention is to provide a method for preparing the lithium-rich manganese-based cathode material described above.

[0031] (1) Prepare the metal salts corresponding to the metal elements in the lithium-rich manganese-based cathode material, mix and dissolve them in a solvent to obtain a dispersion.

[0032] In a preferred embodiment, the metal salt includes lithium salt, manganese salt, nickel salt, iron salt, copper salt, zinc salt, lanthanum salt, aluminum salt, magnesium salt, and optionally cobalt salt.

[0033] In some specific embodiments, the lithium salt includes at least one of lithium chloride, lithium nitrate, lithium sulfate, lithium acetate, lithium carbonate, and lithium phosphate; the manganese salt includes at least one of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate; the nickel salt includes at least one of nickel chloride, nickel nitrate, nickel sulfate, and nickel acetate; the iron salt includes at least one of ferrous chloride, ferrous sulfate, ferrous nitrate, ferric chloride, ferric nitrate, and ferric sulfate; the copper salt includes at least one of copper chloride, copper nitrate, copper sulfate, and copper acetate; the zinc salt includes at least one of zinc chloride, zinc nitrate, zinc sulfate, and zinc acetate; the lanthanum salt includes at least one of lanthanum chloride, lanthanum nitrate, and lanthanum acetate; the aluminum salt includes at least one of aluminum chloride, aluminum nitrate, and aluminum sulfate; the magnesium salt includes at least one of magnesium chloride, magnesium nitrate, magnesium sulfate, and magnesium acetate; and the cobalt salt includes at least one of cobalt chloride, cobalt nitrate, and cobalt sulfate.

[0034] It is understood that the dosage ratio of the metal salt should be adaptively adjusted according to the values ​​of a~j in the preset molecular formula of the lithium-rich manganese-based cathode material.

[0035] In a preferred embodiment, the solvent is deionized water, and the amount of solvent used is 0.8 mL to 2 mL when using 7 mg to 10 mg of the lithium salt.

[0036] (2) Add citric acid to the dispersion, and then adjust the pH to 7.5~8.5. Then perform aging treatment, drying treatment, first sintering treatment, second sintering treatment and quenching treatment in sequence to obtain the lithium-rich manganese-based cathode material.

[0037] In a preferred embodiment, the molar ratio of citric acid to lithium salt in the metal salt is (1.8~2.5):1.

[0038] It is understood that the citric acid can be added directly to the dispersion in its normal solid form, or it can be dissolved into a citric acid solution first before being added to the dispersion. For reference, before pH adjustment, the concentration of citric acid in the dispersion after adding citric acid is 35 mg / mL to 41 mg / mL.

[0039] In a preferred embodiment, the preparation of the dispersion and the addition of citric acid can be assisted by methods such as shaking, stirring, shaking table, centrifugation, ultrasonication, and heating, which helps to accelerate dispersion and obtain a relatively uniform dispersion system. It is understood that the present invention assumes a uniform dispersion phase has already been obtained before the pH adjustment is performed.

[0040] In a preferred embodiment, the pH adjustment is performed using an alkaline reagent, namely ammonia. Those skilled in the art can adjust the concentration of the ammonia according to the production scale corresponding to the dispersion. In this invention, the concentration of the ammonia is not strictly limited, as long as the expected pH can be achieved.

[0041] In a preferred embodiment, the pH includes, but is not limited to, any one or any two of the following: 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, and 8.5.

[0042] In a preferred embodiment, the aging treatment temperature is 70℃~85℃, and the aging treatment time is 5h~15h. In some optional embodiments, the aging treatment temperature includes, but is not limited to, any one or any two of 70, 72, 75, 78, 80, 82, and 85 (℃), and the aging treatment time includes, but is not limited to, any one or any two of 5, 6, 8, 10, 12, and 15 (h).

[0043] In this invention, by aging and limiting the temperature and time for aging, mixed metal ions can form uniform nanoscale precursor particles through slow hydrolysis or complexation reactions, and aging promotes the formation of spherical particles, effectively improving the packing density of the cathode material obtained by subsequent drying and sintering.

[0044] In a preferred embodiment, the drying temperature is 110°C to 140°C, and the drying time is not specifically limited, but is carried out until the solvent is completely evaporated. In some optional embodiments, the drying temperature includes, but is not limited to, any one or any two of 110, 115, 120, 125, 130, 135, and 140 (°C).

[0045] In this invention, by drying and limiting the temperature to which it is suitable, the solvent is removed while avoiding pores or cracks caused by moisture evaporation during sintering, and the porosity and specific surface area of ​​the cathode material precursor are adjusted.

[0046] In a preferred embodiment, the temperature of the first sintering treatment is 400℃~500℃, and the time of the first sintering treatment is 1.5h~5h. In some optional embodiments, the temperature of the first sintering treatment includes, but is not limited to, any one or any two of the following values: 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500 (℃), and the time of the first sintering treatment includes, but is not limited to, any one or any two of the following values: 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5 (h).

[0047] In this invention, a first sintering process is performed, and the temperature and time are limited. Pre-sintering can remove organic residues (such as acetate) in the positive electrode precursor and promote the initial crystallization of transition metal oxides, providing a good structural template for subsequent high-temperature sintering.

[0048] In a preferred embodiment, the temperature of the second sintering treatment is 800℃~1000℃, and the time of the second sintering treatment is 8h~15h. In some optional embodiments, the temperature of the second sintering treatment includes, but is not limited to, any one or any two of the following values: 800, 820, 850, 880, 900, 920, 950, 980, 1000 (℃), and the time of the second sintering treatment includes, but is not limited to, any one or any two of the following values: 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15 (h).

[0049] In this invention, by performing a second sintering process and limiting the temperature and time, lithium ions can be effectively embedded into the transition metal oxide lattice to form a composite structure of lithium-rich phase and layered phase, which promotes grain growth and increases crystallinity, thereby improving the stability of the obtained cathode material.

[0050] As a preferred embodiment, before the first sintering treatment and after the drying treatment, the process further includes: grinding the precursor to obtain a uniform powder solid.

[0051] In a preferred embodiment, after the first sintering treatment and before the second sintering treatment, the process further includes: crushing and plasticizing the precursor, for example, by pressing to obtain a packed solid with a positive electrode shape.

[0052] In a preferred embodiment, the quenching process includes: rapidly placing the precursor obtained from the second sintering process into liquid nitrogen, or spraying liquid nitrogen onto the surface of the precursor obtained from the second sintering process.

[0053] In this invention, liquid nitrogen is used for quenching to prevent abnormal grain growth or phase separation caused by slow cooling. This fixes and maintains the high crystallinity structure, oxygen vacancies, and surface defects after high-temperature sintering, effectively improving the lithium-ion diffusion coefficient of the cathode material.

[0054] A third aspect of the present invention is to provide a solid-state battery.

[0055] The positive electrode of the solid-state battery includes the lithium-rich manganese-based positive electrode material as described in the first aspect. It is understood that the solid-state battery should include a solid positive electrode, a solid negative electrode, a solid electrolyte, and other necessary or non-essential functional components or packaging assemblies, etc., which can be arbitrarily selected and combined by those skilled in the art within the above limitations. When the solid positive electrode of the solid-state battery includes the lithium-rich manganese-based positive electrode material described in this invention, regardless of whether other positive electrode active materials are used, it can be considered an embodiment of this invention. The present invention does not impose any limitations on the preparation method of the solid-state battery.

[0056] A fourth aspect of the present invention is to provide an electrical appliance.

[0057] The electrical equipment mentioned herein includes the solid-state battery as described in the third aspect. It is understood that the electrical equipment can be any device or apparatus that relies on electrical energy to work or operate, including but not limited to new energy vehicles, building electrical equipment, industrial electrical appliances, household and agricultural electrical appliances, etc.; when the solid-state battery is included, any electrical equipment equipped with the solid-state battery can be considered an embodiment of the present invention.

[0058] Example 1 This embodiment provides a lithium-rich manganese-based cathode material (Li 1.18 Mn 0.53 Ni 0.25 Fe 0.01 Cu 0.01 Zn 0.01 La 0.01 Al 0.02 Mg 0.02 O2), the preparation method is as follows: S1. Dissolve nickel acetate tetrahydrate, manganese acetate tetrahydrate, copper acetate monohydrate, magnesium acetate tetrahydrate, zinc acetate dihydrate, aluminum nitrate nonahydrate, lanthanum acetate hydrate, ferric nitrate nonahydrate, and lithium carbonate in deionized water according to the molar ratio of the above chemical formulas. The amount of water added is based on lithium carbonate, with 1 mL of deionized water added for every 8 mg of lithium carbonate. Continue until completely dissolved, and then stir at room temperature for 30 minutes.

[0059] S2. Prepare an aqueous solution of citric acid with a concentration of 0.3 g / mL.

[0060] S3. Add the citric acid solution of S2 dropwise to the mixed salt solution of S1, and measure the volume of the two by the molar ratio of citric acid to lithium carbonate of 2:1; then adjust the pH to 8 with ammonia water, and age it at 80°C for 12 hours by stirring.

[0061] S4. Place the aged solution in a 120°C forced-air drying oven until the solvent water evaporates.

[0062] S5. Grind the completely dried precursor into powder and then sinter it at 450°C for 3 hours.

[0063] S6. Press the sintered precursor into a compact sheet and then sinter at 900°C for 10 hours.

[0064] S7. The precursor after sintering is immediately quenched with liquid nitrogen to obtain the lithium-rich manganese-based cathode material of this embodiment.

[0065] Example 2 The preparation method is exactly the same as in Example 1, except that the molecular formula of the lithium-rich manganese-based cathode material provided in this example is: Li 1.18 Mn 0.49 Ni 0.20 Fe 0.01 Cu 0.01 Zn 0.01 La 0.01 Al 0.02 Mg 0.02 O2.

[0066] Example 3 The preparation method is exactly the same as in Example 1, except that the molecular formula of the lithium-rich manganese-based cathode material provided in this example is: Li 1.18 Mn 0.49 Ni 0.25 Co 0.05 Fe 0.01 Cu 0.01 Zn 0.01 La 0.01 Al 0.02 Mg 0.02 O2.

[0067] Example 4 It is basically the same as Example 1, except that: S3. Stir and age at 85℃ for 10 hours; S5. Sinter at 500℃ for 2.5 hours; S6. Sinter at 950℃ for 8.5 hours.

[0068] Example 5 It is basically the same as Example 1, except that: S3. Stir and age at 75℃ for 13 hours; S5. Sinter at 400℃ for 5 hours; S6. Sinter at 850℃ for 15 hours.

[0069] Comparative Example 1 It is basically the same as Example 1, except that: The molecular formula of the cathode material in this comparative example is Li. 1.18 Mn 0.55 Ni 0.15 Co 0.1 O2; and the corresponding salt for which no undoped element is added in step S1.

[0070] Comparative Example 2 It is basically the same as Example 1, except that the step of "stirring and aging at 80°C for 12 hours" is omitted in step S3.

[0071] Comparative Example 3 It is basically the same as Example 1, except that step S5 is omitted.

[0072] Comparative Example 4 It is basically the same as Example 1, except that the step of "quenching with liquid nitrogen" is omitted in step S7.

[0073] Test case (1) The cathode materials obtained in Example 1 and Comparative Example 1 were subjected to XRD tests, and the results are as follows: Figure 1 As shown.

[0074] (2) The positive electrode materials of each embodiment and the comparative example were assembled to obtain an all-solid-state battery. The steps are as follows: 80 mg of Li6PS5Cl powder was placed in a PTFE mold with a diameter of 10 mm, and a pressure of 2 tons was applied for 5 seconds and pressed into a sheet. Then, 6 mg of mixed positive electrode material (containing the positive electrode materials of each embodiment and the comparative example, Li3InCl6, and Super P, with a mass ratio of 20:15:5, and hand-ground for 30 minutes to ensure uniform mixing) was uniformly added to one side of the sheet electrolyte. Then, a pressure of 4 tons was applied for 5 seconds to obtain the positive electrode side. In addition, In sheets with a molar ratio of 3:1 and Li sheets were stacked together and cold-pressed at 12 MPa for 5 seconds to obtain a Li-In alloy negative electrode. A finished product was cut out using an 8 mm punch and attached to the other side of the sheet electrolyte. Finally, a pressure of 2 tons was applied and held to fix it, thus obtaining a solid-state battery for testing with positive electrode-electrolyte-negative electrode. The whole process was completed in a glove box filled with Ar gas.

[0075] The all-solid-state batteries corresponding to the embodiments and comparative examples were tested: (2.1) Cyclic performance test: 200 cycles of charge and discharge at 0.1C were performed, and the capacity change curve was plotted. The results of Example 1 and Comparative Example 1 are compared as follows. Figure 2 As shown.

[0076] (2.2) Constant current charge-discharge curves: Voltage-capacity change curves were recorded at the 1st, 20th, 100th, and 200th cycles of 200 cyclic charge-discharge cycles at 0.1C. Figure 3 Corresponding to Example 1, Figure 4 This corresponds to Comparative Example 1.

[0077] Table 1

[0078] based on Figure 2 As shown in Table 1, the test batteries of each embodiment of the present invention exhibit significantly better cycle performance than the comparative examples; based on Figure 3 , Figure 4 As can be seen from the comparison, in Example 1 of the present invention, the battery capacity is more stable, the charging performance is better, and the overall electrochemical performance is better than that in Comparative Example 1.

[0079] 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 cathode material, characterized in that, The molecular formula of the lithium-rich manganese-based cathode material is Li. a Mn b Ni c Co d Fe e Cu f Zn g La h Al i Mg j O2; 1 < a ≤ 1.2, 0.4 < b ≤ 0.55, 0.1 < c ≤ 0.25, 0 ≤ d ≤ 0.1, 0 < e ≤ 0.02, 0 < f ≤ 0.02, 0 < g ≤ 0.02, 0 < h ≤ 0.02, 0 < i ≤ 0.02, 0 < j ≤ 0.

02.

2. The method for preparing the lithium-rich manganese-based cathode material as described in claim 1, characterized in that, Includes the following steps: (1) Prepare the metal salts corresponding to the metal elements in the lithium-rich manganese-based cathode material, mix and dissolve them in a solvent to obtain a dispersion; (2) Add citric acid to the dispersion, and then adjust the pH to 7.5~8.

5. Then perform aging treatment, drying treatment, first sintering treatment, second sintering treatment and quenching treatment in sequence to obtain the lithium-rich manganese-based cathode material.

3. The preparation method according to claim 2, characterized in that, The molar ratio of citric acid to lithium salt in the metal salt is (1.8~2.5):

1.

4. The preparation method according to claim 2, characterized in that, The aging process is carried out at a temperature of 70℃ to 85℃ for 5 hours to 15 hours.

5. The preparation method according to claim 2, characterized in that, The drying temperature is 110℃~140℃.

6. The preparation method according to claim 2, characterized in that, The temperature of the first sintering treatment is 400℃~500℃, and the time of the first sintering treatment is 1.5h~5h.

7. The preparation method according to claim 2, characterized in that, The temperature of the second sintering treatment is 800℃~1000℃, and the time of the second sintering treatment is 8h~15h.

8. The preparation method according to claim 2, characterized in that, The process includes a grinding process before the first sintering treatment and after the drying treatment. And / or, after the first sintering treatment and before the second sintering treatment, the process further includes: tableting treatment.

9. A solid-state battery, characterized in that, The positive electrode of the solid-state battery comprises the lithium-rich manganese-based positive electrode material as described in claim 1.

10. An electrical appliance, characterized in that, Including the solid-state battery as described in claim 9.

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