Lithium-rich manganese-based positive electrode material, inorganic-rich positive electrode-electrolyte interface and preparation method and application of lithium-rich manganese-based positive electrode material

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, an inorganic-rich positive electrode-electrolyte interface and a preparation method and application of the lithium-rich manganese-based positive electrode material and the inorganic-rich positive electrode-electrolyte interface. Metal nanoclusters with catalytic activity are uniformly loaded on the surface of the lithium-rich manganese-based positive electrode material; in the electrochemical process, the metal nanoclusters are used for selectively catalyzing decomposition of lithium salt in electrolyte, so that an interface layer dominated by inorganic components is formed in situ, and the interface layer mainly comprises inorganic substances with high ionic conductivity and stable mechanics, such as LiF, Li2O and Li3N. According to the inorganic-rich positive electrode-electrolyte interface, the structural stability and the interface ion transmission efficiency of the lithium-rich manganese-based positive electrode material under a high-voltage condition can be remarkably improved, and the dissolution of transition metal and the release of lattice oxygen are effectively inhibited, so that the cycling stability and the rate capability of the battery are improved. The method is simple in process, mild in condition, easy to implement on a large scale and suitable for the high-energy-density lithium ion battery positive electrode material.

Description

Technical Field

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

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In the lithium-ion battery cathode material system, lithium-rich manganese-based cathode materials are characterized by high discharge specific capacity (>250 mAh g⁻¹). -1 With its high operating voltage (3.6 V), lithium-rich manganese-based cathode materials are considered next-generation high-energy-density lithium-ion battery cathode materials. However, under high-voltage cycling conditions, lithium-rich manganese-based cathode materials are prone to irreversible lattice oxygen precipitation and surface structure degradation, leading to continuous capacity decay and voltage decline, which limits the practical application of this material. Studies have shown that the composition and structural characteristics of the cathode-electrolyte interface play a crucial role in the electrochemical stability and long-cycle performance of lithium-rich manganese-based materials.

[0004] In traditional lithium-ion battery systems, the highest occupied molecular orbital energy level of electrolyte solvent molecules is higher than that of lithium salt anions. This makes it easier for solvent molecules to preferentially undergo oxidative decomposition on the cathode surface within the high-voltage operating window of lithium-rich manganese-based cathode materials. This reaction pathway tends to generate organic components such as alkyl lithium carbonate. Such cathode-electrolyte interfaces rich in organic components have low mechanical modulus and poor chemical stability, making them prone to breakage and reconstruction during electrochemical cycling. This not only continuously consumes limited lithium sources and electrolytes but also exacerbates the dissolution of transition metal ions and the release of lattice oxygen in lithium-rich manganese-based cathode materials, ultimately leading to increased battery impedance and performance failure.

[0005] To address the interfacial instability issues in lithium-rich manganese-based cathode materials during cycling, existing technologies primarily employ inert surface coatings (such as metal oxides and fast-ion conductors) and electrolyte optimization. However, traditional surface coating techniques often struggle to precisely control the coating thickness and distribution, and the interfacial bonding between the coating and the substrate is weak, leading to easy peeling during long-term cycling and thus limiting the sustained suppression of interfacial side reactions. While electrolyte optimization strategies can modulate the interfacial chemical environment to some extent, they typically fail to fundamentally alter the thermodynamic trend of preferential decomposition of electrolyte components at high voltages. Consequently, the electrode-electrolyte interface remains predominantly composed of organic components, resulting in insufficient mechanical strength and electrochemical stability, making it difficult to meet the long-term cycling requirements of lithium-rich manganese-based cathode materials at high operating voltages. Summary of the Invention

[0006] In view of this, the present invention provides a lithium-rich manganese-based cathode material, an inorganic-rich cathode-electrolyte interface, its preparation method, and its application. The present invention introduces catalytically active sites on the surface of the lithium-rich manganese-based cathode material, breaking through the limitations of traditional cathode-electrolyte interface reaction pathways, inducing preferential decomposition of lithium salts and promoting the generation of inorganic components, thereby constructing a stable, dense, and high-voltage-suitable inorganic-rich cathode-electrolyte interface to improve the cycle stability and electrochemical performance of the lithium-rich manganese-based cathode material.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a lithium-rich manganese-based cathode material, wherein the surface of the lithium-rich manganese-based cathode material is loaded with uniformly dispersed metal nanoclusters M, the composition of which is M-Li. a Mn b Ni c Co d O2; Wherein, 1.15≤a≤1.30, 0.50≤b≤0.60, 0.10≤c≤0.20, 0.10≤d≤0.20, and a+b+c+d=2; The metal nanoclusters M include at least one of Ru, Rh, Pd, Ag, Ir, Pt, and Au.

[0008] Furthermore, the metal nanocluster M is Pt.

[0009] Furthermore, the size of the metal nanoclusters M is 1~10 nm. The metal nanoclusters M are stably bonded to the lithium-rich manganese-based cathode material matrix.

[0010] Secondly, the present invention provides a method for preparing the lithium-rich manganese-based cathode material described in the first aspect, the specific steps of which are as follows: S1: Mix the metal salt solutions of lithium, manganese, nickel and cobalt, add a complexing agent, stir and sonicate to obtain a lithium-rich manganese-based cathode material precursor solution, then prepare a lithium-rich manganese-based cathode material precursor, and pyrolyze the lithium-rich manganese-based cathode material precursor to obtain a lithium-rich manganese-based cathode material matrix. S2: The lithium-rich manganese-based cathode material matrix obtained in step S1 and the metal salt are added to the solvent according to a predetermined feeding ratio, and ultrasonically dispersed to make them uniformly dispersed; then, the mixture is continuously stirred and evaporated at a predetermined temperature to remove the solvent and obtain a dry mixture. S3: Under inert atmosphere, the mixture obtained in step S2 is subjected to high-temperature annealing to obtain a lithium-rich manganese-based cathode material with surface-loaded metal nanoclusters M.

[0011] Furthermore, in S1, the stoichiometric ratio of lithium, manganese, nickel, and cobalt is 1.03a:b:c:d, where: 1.15≤a≤1.30, 0.50≤b≤0.60, 0.10≤c≤0.20, 0.10≤d≤0.20, and a+b+c+d=2. Lithium is added in excess by 3% to compensate for lithium loss during the high-temperature sintering process.

[0012] Furthermore, in S1, the complexing agent is citric acid.

[0013] Furthermore, in S1, the stirring operation is as follows: stirring at 400~600 rpm for 1~3 h.

[0014] Furthermore, in S1, the ultrasound time is 20-40 minutes.

[0015] Further, in S1, the method for preparing the lithium-rich manganese cathode material precursor includes at least one of spray drying, co-precipitation, sol-gel, high-temperature solid-state method, or molten salt method; preferably, the lithium-rich manganese-based cathode material precursor is prepared by spray drying.

[0016] Furthermore, in S1, the spray drying feed rate is 3~15 mL / min; the inlet air temperature is 200~250 ℃; and the outlet air temperature is 100~120 ℃.

[0017] Furthermore, in S1, the pyrolysis process is performed at 2~5 °C for min under air atmosphere. -1 The temperature was increased to 850~950 ℃ at a heating rate and held for 8~12 h.

[0018] Further, in S2, the metal salt is selected from at least one of the metal chlorides, metal nitrates or acetylacetone metal compounds of Ru, Rh, Pd, Ag, Ir, Pt, Au.

[0019] Furthermore, in S2, the mass ratio of the lithium-rich manganese-based cathode material matrix to the corresponding metal atoms is 100:1 to 1000:1.

[0020] Furthermore, in S2, the ultrasonic treatment time is 10~60 min.

[0021] Furthermore, in S2, the stirring and evaporation process is carried out at a speed of 300~1200 rpm, a temperature of 40~80 ℃, and a processing time of 2~12 h.

[0022] Further, in S2, the solvent is selected from at least one of deionized water, anhydrous ethanol, acetone and N-methylpyrrolidone, and the ratio of the solvent to the lithium-rich manganese-based cathode material matrix is ​​5~40:1 mL / g.

[0023] Furthermore, in S3, the inert atmosphere is argon or nitrogen.

[0024] Furthermore, in S3, the annealing temperature is 250~500 ℃, and the annealing time is 2~10 h. The metal salt decomposes in situ on the surface of the lithium-rich manganese-based cathode material matrix and forms metal nanoclusters, thereby obtaining a lithium-rich manganese-based cathode material with surface-loaded metal nanoclusters.

[0025] Thirdly, this invention provides a method for constructing an inorganic cathode-electrolyte interface rich in lithium-manganese-based cathode materials, comprising the following steps: By introducing metal nanoclusters as catalytic sites onto the surface of the lithium-rich manganese-based cathode material matrix as described in the first aspect, lithium salts in the electrolyte are preferentially decomposed, thereby constructing an inorganic-rich cathode-electrolyte interface.

[0026] Further, the steps specifically involve: uniformly dispersing the lithium-rich manganese-based cathode material described in the first aspect with conductive carbon, binder, and solvent to obtain a cathode slurry; coating the cathode slurry onto the surface of a current collector; and obtaining a lithium-rich manganese-based cathode sheet through drying, slicing, and rolling. A lithium metal anode, electrolyte, and separator are then matched and assembled into a lithium-ion battery under an inert atmosphere. The selective adsorption and catalytic effect of metal nanoclusters on the surface of the lithium-rich manganese-based cathode material promotes the preferential decomposition of lithium salts during the initial charge and discharge process, thereby constructing an inorganic-rich cathode-electrolyte interface on the surface of the lithium-rich manganese-based cathode material.

[0027] Furthermore, the inorganic-rich cathode-electrolyte interface is formed by the selective adsorption and preferential decomposition of lithium salts in the electrolyte by the catalytic sites of surface metal nanoclusters during charging and discharging; its components include at least one of LiF, Li2O, and Li3N.

[0028] Furthermore, the lithium salt in the electrolyte includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium bis(trifluoromethanesulfonyl)imide.

[0029] Further, the solvent of the electrolyte is an ester solvent; preferably, the ester solvent is at least one selected from ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, and ethyl acetate.

[0030] Furthermore, the conductive agent is selected from at least one of graphite, acetylene black, Super P, carbon nanotubes, graphene, and Ketjen black.

[0031] Furthermore, the adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose, and sodium alginate.

[0032] Furthermore, the current collector is selected from at least one of aluminum foil, carbon-coated aluminum foil, nickel foil, and stainless steel foil.

[0033] Furthermore, the solvent is deionized water or N-methylpyrrolidone.

[0034] Fourthly, the present invention provides an inorganic cathode-electrolyte interface for lithium-rich manganese-based cathode materials obtained by the construction method described in the third aspect.

[0035] Fifthly, the present invention provides the application of the construction method described in the third aspect or the inorganic cathode-electrolyte interface of the lithium-rich manganese-based cathode material described in the fourth aspect in lithium-ion batteries.

[0036] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The present invention can effectively control the formation process of the cathode-electrolyte interface, improve the inorganic degree and structural stability of the interface layer, thereby improving the interface stability of the cathode material under high voltage conditions.

[0037] (2) The inorganic-rich cathode-electrolyte interface formed by the present invention originates from the in-situ evolution of the interfacial reaction during the electrochemical process. It is more tightly bonded to the cathode material matrix and is less prone to detachment or breakage, which helps to maintain the interfacial integrity of the cathode material under long-cycle and high-voltage working conditions.

[0038] (3) The preparation process of the present invention is simple and the reaction conditions are mild. The metal salt precursors used are widely available and highly reproducible, making it easy to scale up. It is compatible with existing cathode material preparation and lithium-ion battery manufacturing processes, which is conducive to achieving stable and controllable large-scale production, thus providing technical support for the industrial application of lithium-rich manganese-based cathode materials in high-energy-density lithium-ion batteries. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 The X-ray diffraction patterns of Pt-LRMO-200, Pt-LRMO-1000 and LRMO cathode materials prepared in Examples 1, 2 and Comparative Example 1 of this invention are shown below. Figure 2The images show scanning electron microscope (SEM) images of Pt-LRMO-200, Pt-LRMO-1000, and LRMO cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention; wherein, (a) is Pt-LRMO-200, scale bar 500 nm, (b) is Pt-LRMO-1000, scale bar 500 nm, (c) is LRMO, scale bar 500 nm, (d) is Pt-LRMO-200, scale bar 200 nm, (e) is Pt-LRMO-1000, scale bar 200 nm, and (f) is LRMO, scale bar 200 nm. Figure 3 Transmission electron microscope images of Pt-LRMO-200, Pt-LRMO-1000, and LRMO cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention are shown below. (a) is Pt-LRMO-200, scale bar 20 nm; (b) is Pt-LRMO-1000, scale bar 20 nm; (c) is LRMO, scale bar 20 nm; (d) is Pt-LRMO-200, scale bar 5 nm; (e) is Pt-LRMO-1000, scale bar 5 nm; and (f) is LRMO, scale bar 5 nm. Figure 4 The Pt-LRMO-200 and LRMO cathode materials prepared in Example 1 and Comparative Example 1 of this invention were subjected to a temperature of 0.2C (1C = 200 mA g) at 0.2C. -1 Transmission electron microscope images after 5 cycles at current density; where (a) is Pt-LRMO-200 and (b) is LRMO; Figure 5 The graphs show the cycling performance of the cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention at a current density of 0.2C. Figure 6 The graphs show the cycling performance of the cathode materials prepared in Examples 1, 2 and Comparative Example 1 of this invention at a current density of 1C. Detailed Implementation

[0041] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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.

[0042] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0043] Example 1 In this embodiment, a lithium-rich manganese-based cathode material with Pt nanoclusters loaded on its surface was prepared by the following method, and an inorganic-rich cathode-electrolyte interface was constructed in the subsequent electrochemical process. The specific steps are as follows: (1) According to the stoichiometric ratio of Li:Mn:Ni:Co = 1.236:0.54:0.13:0.13, 18.91 g of lithium acetate dihydrate, 19.85 g of manganese acetate tetrahydrate, 4.85 g of nickel acetate tetrahydrate, and 4.86 g of cobalt acetate tetrahydrate were weighed out respectively. The above raw materials were dissolved in 1 L of deionized water, and 63.04 g of citric acid monohydrate was added as a complexing agent. The mixed solution was then stirred at 500 rpm for 2 h and ultrasonically dispersed for 30 min to obtain a uniform precursor solution. The lithium-rich manganese-based cathode material precursor was prepared by spray drying technology, wherein the feed rate of the spray dryer was 5 mL / min. -1 The inlet air temperature was 220 ℃, and the outlet air temperature was 110 ℃. Then, the lithium-rich manganese-based cathode material precursor was placed in an alumina crucible and heated in air at 3 ℃ for 3 min. -1 The temperature was increased to 900 °C at a heating rate and held for 10 h. After natural cooling to room temperature, a lithium-rich manganese-based cathode material matrix (Li) was obtained. 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 (abbreviated as LRMO).

[0044] (2) 1 g of the lithium-rich manganese-based cathode material matrix obtained in step (1) and 10 mg of platinum acetylacetonate were added to 10 mL of anhydrous ethanol, wherein the mass ratio of the lithium-rich manganese-based cathode material matrix to Pt atoms was 200:1. The mixture was ultrasonically treated for 20 min to ensure uniform dispersion. Subsequently, the mixture was stirred at 500 rpm for 4 h at 80 ℃ to gradually remove the solvent and obtain a dry mixture.

[0045] (3) The above mixture was placed in argon and annealed at 300 °C for 4 h to allow platinum acetylacetone to decompose in situ on the surface of the lithium-rich manganese-based cathode material matrix, thereby obtaining a lithium-rich manganese-based cathode material with Pt nanoclusters loaded on the surface, denoted as Pt-LRMO-200.

[0046] (4) The lithium-rich manganese-based cathode material obtained in step (3), the conductive agent Super P, and the binder sodium carboxymethyl cellulose were mixed at a solid mass ratio of 8:1:1, wherein the sodium carboxymethyl cellulose was added in the form of an aqueous solution with a mass fraction of 1 wt%. The mixture was then homogenized for 20 min using a vacuum stirrer to fully disperse the components and simultaneously remove air bubbles entrained in the slurry, resulting in a uniform and stable cathode slurry. The cathode slurry was uniformly coated onto the surface of an aluminum foil current collector, dried at 80 ℃ for 12 h, rolled under 4 T pressure, and cut into circular pieces with a diameter of 10 mm to obtain a lithium-rich manganese-based cathode sheet. The cathode sheet was then combined with a lithium metal anode and Celgard... The 2400 diaphragm and commercial ester electrolyte were assembled in an argon-filled glove box. The water and oxygen content in the glove box was both less than 0.1 ppm. The electrolyte consisted of 1 mol / L lithium hexafluorophosphate dissolved in a mixed solvent of ethylene carbonate and methyl ethyl carbonate (volume ratio 3:7), with 2 vol% vinyl carbonate added as a negative electrode film-forming additive.

[0047] (5) The electrochemical performance of the assembled battery was tested using a constant current charge-discharge method, with a test voltage range of 2.0~4.8 V. During the initial charge-discharge process of the battery, the selective adsorption and catalytic effect of Pt nanoclusters on the surface of the cathode material were utilized to induce preferential decomposition of lithium hexafluorophosphate in the electrolyte, thereby constructing a cathode-electrolyte interface dominated by LiF inorganic components in situ on the surface of the lithium-rich manganese-based cathode material, giving the obtained lithium-rich manganese-based cathode material excellent interfacial stability.

[0048] Example 2: In this embodiment, the preparation method of the lithium-rich manganese-based cathode material and the construction method of its cathode-electrolyte interface are basically the same as in Example 1, except that in step (2), the amount of platinum acetylacetone added is adjusted to 2 mg, so that the mass ratio of the lithium-rich manganese-based cathode material matrix to platinum is 1000:1. The lithium-rich manganese-based cathode material prepared in this way is denoted as Pt-LRMO-1000.

[0049] Comparative Example 1: In this comparative example, the preparation method of the lithium-rich manganese-based cathode material and the construction method of its cathode-electrolyte interface are basically the same as those in Example 1. The difference is that the metal precursor platinum acetylacetone was not introduced in the preparation process. The lithium-rich manganese-based cathode material prepared in this way is denoted as LRMO.

[0050] Explanation of the attached results: Figure 1 The figures show the X-ray diffraction patterns of the Pt-LRMO-200, Pt-LRMO-1000, and LRMO cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention. As can be seen from the figures, all three samples exhibit typical lithium-rich manganese-based matrix oxide structure characteristics, with their main diffraction peaks at essentially the same positions. No obvious impurity phase diffraction peaks were observed, indicating that introducing a small amount of metal nanoclusters onto the surface of the lithium-rich manganese-based cathode material did not disrupt the main crystal structure of the material.

[0051] Figure 2The images show scanning electron microscope (SEM) images of the Pt-LRMO-200, Pt-LRMO-1000, and LRMO cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention; wherein, (a) is Pt-LRMO-200, scale bar 500 nm, (b) is Pt-LRMO-1000, scale bar 500 nm, (c) is LRMO, scale bar 500 nm, (d) is Pt-LRMO-200, scale bar 200 nm, (e) is Pt-LRMO-1000, scale bar 200 nm, and (f) is LRMO, scale bar 200 nm. Figure 2 As shown, the LRMO samples exhibit a regular polyhedral primary particle morphology, with closely packed particles and a particle size of 200–300 nm. Figure 2 c. Figure 2 f); Pt-LRMO-200 material obtained after modification with different Pt contents ( Figure 2 a, Figure 2 d) and Pt-LRMO-1000 ( Figure 2 b、 Figure 2 e) The polyhedral morphology and particle size characteristics of LRMO were preserved overall, and no obviously separated or agglomerated Pt metal particles were observed on the surface.

[0052] Figure 3 Transmission electron microscope (TEM) images of Pt-LRMO-200, Pt-LRMO-1000, and LRMO cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention are shown. In each image, (a) is Pt-LRMO-200 (scale bar 20 nm), (b) is Pt-LRMO-1000 (scale bar 20 nm), (c) is LRMO (scale bar 20 nm), (d) is Pt-LRMO-200 (scale bar 5 nm), (e) is Pt-LRMO-1000 (scale bar 5 nm), and (f) is LRMO (scale bar 5 nm). Figure 3 a, Figure 3 As can be seen, the surface of the Pt-LRMO-200 sample is loaded with uniformly dispersed Pt metal nanoclusters with a size of 1~2 nm. Figure 3 b、 Figure 3 As shown in Figure e, the Pt-LRMO-1000 sample surface is loaded with fewer Pt metal nanoclusters with a size of less than 1 nm. Figure 3 c. Figure 3 As shown in f, the LRMO sample is an irregular polyhedron with good crystallinity, and clear layered lattice fringes can be observed.

[0053] Figure 4 The Pt-LRMO-200 and LRMO cathode materials prepared in Example 1 and Comparative Example 1 of this invention were subjected to a temperature of 0.2C (1C = 200 mA g) at 0.2C. -1Transmission electron microscopy images after 5 cycles at current density; where (a) is Pt-LRMO-200 and (b) is LRMO. Figure 4 As shown, a continuous, dense interface layer rich in LiF nanocrystals was formed on the surface of Pt-LRMO-200. In contrast, the interface layer of the LRMO sample had an uneven thickness distribution and exhibited an overall amorphous structure. These results indicate that metal nanoclusters can help regulate the reaction behavior of the cathode interface, promote the preferential decomposition of lithium salt in the electrolyte on the cathode surface, and construct an inorganic-dominated cathode-electrolyte interface in situ.

[0054] Figure 5 The figures show the cycling performance curves of the cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention at a current density of 0.2C. As can be seen from the figures, compared with LRMO (74.0%), the capacity retention rates of Pt-LRMO-200 and Pt-LRMO-1000 samples reached 97.6% and 92.2% respectively at 0.2C, indicating a significant improvement in cycling stability. This demonstrates that the constructed inorganic-rich cathode-electrolyte interface can effectively suppress interfacial side reactions, thereby improving the cycling performance of the lithium-rich manganese-based cathode material.

[0055] Figure 6 The graphs show the cycling performance of the cathode materials prepared in Examples 1, 2, and Comparative Example 1 of this invention at a current density of 1C. Figure 6 As shown, after 200 cycles, the Pt-LRMO-200 and Pt-LRMO-1000 samples still maintained a strength of 181.3 mAh g⁻¹. -1 and 158.1 mAh g -1 The discharge specific capacity was significantly higher than that of the LRMO sample (135.9 mAh g⁻¹). -1 This result indicates that the formed inorganic-rich cathode-electrolyte interface is beneficial for improving interfacial ion transport characteristics, further enhancing the high-rate performance of lithium-rich manganese-based cathode materials.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium-rich manganese-based cathode material, characterized in that, The lithium-rich manganese-based cathode material has uniformly dispersed metal nanoclusters M on its surface, with a composition of M-Li. a Mn b Ni c Co d O2; The metal nanoclusters M include at least one of Ru, Rh, Pd, Ag, Ir, Pt, and Au; Where 1.15≤a≤1.30, 0.50≤b≤0.60, 0.10≤c≤0.20, 0.10≤d≤0.20, and a+b+c+d=2.

2. The lithium-rich manganese-based cathode material as described in claim 1, characterized in that, The metal nanocluster M is Pt; the size of the metal nanocluster M is 1~10 nm.

3. The method for preparing the lithium-rich manganese-based cathode material as described in claim 1, characterized in that, The specific steps are as follows: S1: Mix the metal salt solutions of lithium, manganese, nickel and cobalt, add a complexing agent, stir and sonicate to obtain a lithium-rich manganese-based cathode material precursor solution, then prepare a lithium-rich manganese-based cathode material precursor, and pyrolyze the lithium-rich manganese-based cathode material precursor to obtain a lithium-rich manganese-based cathode material matrix. S2: The lithium-rich manganese-based cathode material matrix obtained in step S1 and the metal salt are added to the solvent according to a predetermined feeding ratio, and ultrasonically dispersed to make them uniformly dispersed; then, the mixture is continuously stirred and evaporated at a predetermined temperature to remove the solvent and obtain a dry mixture. S3: Under inert atmosphere, the mixture obtained in step S2 is subjected to high-temperature annealing to obtain a lithium-rich manganese-based cathode material with surface-loaded metal nanoclusters M.

4. The preparation method according to claim 3, characterized in that, In S1, the stoichiometric ratio of lithium, manganese, nickel and cobalt is 1.03a:b:c:d, where: 1.15≤a≤1.30, 0.50≤b≤0.60, 0.10≤c≤0.20, 0.10≤d≤0.20, and a+b+c+d=2; And / or, in S1, the complexing agent is citric acid; And / or, in S1, the stirring operation is: stirring at 400~600 rpm for 1-3 hours; And / or, in S1, the ultrasound time is 20~40 min; And / or, in S1, the method for preparing the lithium-rich manganese cathode material precursor includes at least one of spray drying, co-precipitation, sol-gel, high-temperature solid-state method or molten salt method; preferably, the lithium-rich manganese-based cathode material precursor is prepared by spray drying. And / or, in S1, the spray drying feed rate is 3~15 mL / min; the inlet air temperature is 200~250 ℃, and the outlet air temperature is 100~120 ℃; And / or, in S1, the pyrolysis process is performed at 2~5 °C min in air atmosphere. -1 The temperature is increased to 850~950℃ at a heating rate and held for 8~12 hours.

5. The preparation method according to claim 3, characterized in that, In S2, the metal salt is selected from at least one of the following: metal chlorides, metal nitrates, or metal compounds of Ru, Rh, Pd, Ag, Ir, Pt, Au; And / or, in S2, the mass ratio of the lithium-rich manganese-based cathode material matrix to the corresponding metal atoms is 100:1 to 1000:1; And / or, in S2, the ultrasonic treatment time is 10~60 min; And / or, in S2, the stirring and evaporation process is carried out at a speed of 300~1200 rpm, a temperature of 40~80 ℃, and a processing time of 2~12 h; And / or, in S2, the solvent is selected from at least one of deionized water, anhydrous ethanol, acetone and N-methylpyrrolidone, and the ratio of the solvent to the lithium-rich manganese-based cathode material matrix is ​​5~40:1 mL / g; And / or, in S3, the inert atmosphere is argon or nitrogen; And / or, in S3, the annealing temperature is 250~500 ℃, and the annealing time is 2~10 h.

6. A method for constructing an inorganic cathode-electrolyte interface for a lithium-rich manganese-based cathode material, characterized in that, Includes the following steps: By introducing metal nanoclusters as catalytic sites onto the surface of the lithium-rich manganese-based cathode material matrix as described in claim 1, lithium salts in the electrolyte are preferentially decomposed, thereby constructing an inorganic-rich cathode-electrolyte interface.

7. The construction method as described in claim 6, characterized in that, The specific steps are as follows: the lithium-rich manganese-based cathode material described in the first aspect is uniformly dispersed with conductive carbon, binder, and solvent to obtain a cathode slurry; the cathode slurry is then coated onto the surface of a current collector, and after drying, slicing, and rolling, a lithium-rich manganese-based cathode sheet is obtained; a lithium metal anode, electrolyte, and separator are matched, and a lithium-ion battery is assembled under an inert atmosphere; the selective adsorption and catalytic effect of metal nanoclusters on the surface of the lithium-rich manganese-based cathode material is utilized to promote the preferential decomposition of lithium salt during the initial charge and discharge process, thereby constructing an inorganic cathode-electrolyte interface on the surface of the lithium-rich manganese-based cathode material.

8. The construction method as described in claim 7, characterized in that, The inorganic-rich cathode-electrolyte interface is formed by the selective adsorption of lithium salts in the electrolyte by surface metal nanoclusters during charge and discharge; its components include at least one of LiF, Li2O, and Li3N. And / or, the lithium salt in the electrolyte includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium bis(trifluoromethanesulfonyl)imide; And / or, the solvent of the electrolyte is an ester solvent; preferably, the ester solvent is at least one selected from ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, and ethyl acetate. And / or, the conductive agent is selected from at least one of graphite, acetylene black, Super P, carbon nanotubes, graphene, and Ketjen black; And / or, the adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose, and sodium alginate; And / or, the current collector is selected from at least one of aluminum foil, carbon-coated aluminum foil, nickel foil, and stainless steel foil; And / or, the solvent is deionized water or N-methylpyrrolidone.

9. The inorganic cathode-electrolyte interface of the lithium-rich manganese-based cathode material obtained by the construction method according to any one of claims 6-8.

10. The application of the construction method according to any one of claims 6-8 or the inorganic cathode-electrolyte interface of the lithium-rich manganese-based cathode material according to claim 9 in lithium-ion batteries.

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