High-capacity lithium-rich manganese-based positive electrode material as well as preparation method and application thereof

Abstract

The invention provides a high-capacity lithium-rich manganese-based positive electrode material as well as a preparation method and application thereof, the high-capacity lithium-rich manganese-based positive electrode material is prepared from a lithium-rich manganese-based precursor, primary particles and secondary spherical particles are formed in situ, and coating layers are arranged on the surfaces of the primary particles and the secondary spherical particles; and the coating layer comprises an aluminum oxide layer and a solid electrolyte layer. The aluminum oxide layer and the solid electrolyte layer are coated on the surfaces of the primary particles and the secondary spherical particles, a continuous ion / electron dual-conduction network is formed in the all-solid-state lithium ion battery, and a chemical bonding enhanced interface is formed between the continuous ion / electron dual-conduction network and a matrix, so that the positive electrode material greatly reduces the transmission resistance of lithium ions in the particles; and lithium ions can directly pass through the interiors of the particles, so that the positive electrode material has good capacity in an all-solid-state battery system.

Description

Technical Field

[0001] This invention belongs to the field of cathode material technology, and particularly relates to a high-capacity lithium-rich manganese-based cathode material, its preparation method, and its application. Background Technology

[0002] With the increasing global demand for clean energy, lithium-ion batteries, as a highly efficient energy storage device, have been widely used in electric vehicles, portable electronic devices, and other fields. However, traditional lithium-ion batteries use flammable organic liquid electrolytes, posing safety hazards such as leakage, fire, and even explosion, which limits their further development in fields with high safety requirements. Furthermore, the unstable interface between the organic liquid electrolyte and electrode materials can lead to side reactions during battery cycling, causing capacity decay and shortened lifespan.

[0003] All-solid-state batteries use solid electrolytes instead of traditional organic liquid electrolytes, fundamentally solving safety issues such as leakage and flammability, and significantly improving battery safety. Simultaneously, solid electrolytes possess excellent mechanical properties, effectively suppressing lithium dendrite growth and preventing short circuits caused by lithium dendrites piercing the separator, further enhancing battery safety and stability. Furthermore, solid electrolytes exhibit higher thermal stability, enabling operation over a wider temperature range and expanding battery application scenarios. Moreover, all-solid-state batteries can achieve higher energy densities, potentially meeting the urgent demand for high-energy-density batteries in electric vehicles with long driving ranges and large-scale energy storage systems. Therefore, all-solid-state batteries are considered a crucial development direction for next-generation high-safety, high-energy-density batteries, attracting widespread attention and in-depth research from academia and industry.

[0004] All-solid-state batteries currently face challenges such as an immature system and high manufacturing costs. Therefore, achieving high energy density is crucial to reducing their watt-hour cost. Energy density is largely determined by the cathode material. Lithium-rich manganese-based cathode materials, with their ultra-high theoretical specific capacity (reaching over 250-300 mAh / g) and high operating voltage, can significantly improve the energy density of lithium-ion batteries, making them one of the key cathode materials for achieving high-energy-density batteries. Their crystal structure typically consists of layered and rock-salt phase structures. This unique structure allows for the insertion and extraction of more lithium ions, thus providing high capacity. Furthermore, lithium-rich manganese-based cathode materials have a high manganese content. Manganese resources are abundant and relatively inexpensive, which helps reduce battery costs and improve the battery's market competitiveness.

[0005] However, despite the significant advantages of lithium-rich manganese-based cathode materials in improving battery energy density and reducing costs, they still face many challenges in practical applications. Lithium-rich manganese-based materials typically consist of nanoscale primary particles agglomerated into micron-sized secondary spheres. In liquid batteries, the electrolyte can wet the internal pores to achieve high capacity (>250 mAh / g). However, in all-solid-state battery systems, various interfaces form between the cathode and anode, and in the electrolyte composite material. These interface problems prevent the solid electrolyte from effectively penetrating into the secondary spheres, resulting in a lack of physical contact, solid-solid conduction, and increased interfacial resistance of the charge transfer layer due to the disruption of lithium-ion conduction pathways. Simultaneously, the formation of interfacial byproducts and the interruption of lithium-ion diffusion lead to non-uniform contact: voids and pores, high interfacial resistance, and limited lithium-ion migration severely restrict battery performance due to the interface problems between the cathode material and the solid electrolyte. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a high-capacity lithium-rich manganese-based cathode material, wherein the high-capacity lithium-rich manganese-based cathode material is prepared by in-situ forming primary particles and secondary spherical particles from a lithium-rich manganese-based precursor, and the surface of the primary particles and the secondary spherical particles are coated with a coating layer.

[0007] The coating layer includes an alumina layer and a solid electrolyte layer.

[0008] Preferably, the particle size of the primary particles is 20~500 nm;

[0009] The particle size of the secondary spherical particles is 200 nm to 100 μm.

[0010] Preferably, the solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0011] Preferably, when the solid electrolyte is selected from oxide solid electrolytes and / or halide solid electrolytes, the coating layer further includes a conductive carbon layer disposed on the surface of the solid electrolyte layer.

[0012] Preferably, the thickness of the alumina layer is 2~5 nm;

[0013] The thickness of the solid electrolyte layer is 3~8 nm;

[0014] The thickness of the conductive carbon layer is 5~10 nm.

[0015] This invention provides a method for preparing the high-capacity lithium-rich manganese-based cathode material described in the above technical solution, comprising the following steps:

[0016] S1: Modify the gas-solid interface of the lithium-rich manganese-based cathode matrix material to obtain a lithium-rich manganese-based cathode material with oxygen vacancies.

[0017] S2: Mix the lithium-rich manganese-based cathode material with oxygen vacancies with water or an organic solvent, add Al(OH)3 colloid, stir evenly, and obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0018] S3: The lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface is mixed with a solid electrolyte precursor or solid electrolyte and then ultrasonically dispersed to obtain a gel-state composite.

[0019] S4: The gel-state composite is permeated and tempered at 180~200℃ and 2~5MPa to obtain a high-capacity lithium-rich manganese-based cathode material.

[0020] Preferably, the tempering temperature is 500~700℃; the tempering time is 1~7h.

[0021] Preferably, the lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface, conductive carbon, solid electrolyte precursor or solid electrolyte are mixed and then ultrasonically dispersed to obtain a gel-state composite.

[0022] The conductive carbon includes one or more of graphene, carbon nanotubes, and conductive carbon black.

[0023] Preferably, the gas-solid interface modification is performed in a mixture of NH3 and Ar at 250-350°C for 1.5-2.5 hours.

[0024] This invention provides a battery comprising a positive electrode, a negative electrode, and a solid electrolyte;

[0025] The positive electrode sheet includes the high-capacity lithium-rich manganese-based positive electrode material described in the above technical solution;

[0026] The negative electrode sheet includes a negative electrode active material, which is selected from one or more of graphite, artificial graphite, silicon carbide materials, lithium metal composite negative electrode and lithium carbon negative electrode materials;

[0027] The solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0028] This invention provides a high-capacity lithium-rich manganese-based cathode material. The high-capacity lithium-rich manganese-based cathode material comprises in-situ formed primary particles and secondary spherical particles prepared from a lithium-rich manganese-based precursor. Both the primary and secondary spherical particles have a coating layer on their surface; the coating layer includes an alumina layer and a solid electrolyte layer. By coating the primary and secondary spherical particles with an alumina layer and a solid electrolyte layer, this invention forms a continuous ion / electron dual-conductivity network in an all-solid-state lithium battery. These layers form a chemically bonded enhanced interface with the substrate, significantly reducing the resistance to lithium-ion transport within the particles and allowing lithium ions to directly penetrate the particles, resulting in optimal capacity utilization. Attached Figure Description

[0029] Figure 1 The first-efficiency curves of the batteries prepared in Example 1 and Comparative Example 1 of this invention are shown.

[0030] Figure 2 The graph shows the capacity retention rate of the batteries prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0031] This invention provides a high-capacity lithium-rich manganese-based cathode material, wherein the high-capacity lithium-rich manganese-based cathode material is prepared by in-situ forming primary particles and secondary spherical particles from a lithium-rich manganese-based precursor, and the surface of both the primary particles and the secondary spherical particles has a coating layer.

[0032] The coating layer includes an alumina layer and a solid electrolyte layer.

[0033] The high-capacity lithium-rich manganese-based cathode material provided by this invention consists of in-situ formed primary particles and secondary spherical particles prepared from lithium-rich manganese-based precursors. Through wet gel permeation and high-pressure treatment, the surfaces of the secondary spherical particles and primary particles are simultaneously coated to form a continuous ion / electron dual-conductivity network. Chemical bonds are formed between the coating layer and the matrix to enhance interfacial stability.

[0034] In this invention, the coating layer comprises an alumina layer and a solid electrolyte layer. The alumina layer is in contact with the surface of primary or secondary spherical particles, and the solid electrolyte layer is then coated on the surface of the alumina layer. The alumina layer is obtained by coating Al(OH)3 colloid and then tempering; the solid electrolyte layer is formed by coating a solid electrolyte raw material and then tempering. In this invention, the thickness of the alumina layer is 2-5 nm; the thickness of the solid electrolyte layer is 3-8 nm.

[0035] In this invention, the particle size of the primary particles is 20~500nm; the particle size of the secondary spherical particles is 200nm~100μm.

[0036] The solid electrolyte described in this invention is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0037] When the solid electrolyte in this invention is selected from oxide solid electrolytes and / or halide solid electrolytes, the coating layer further includes a conductive carbon layer disposed on the surface of the solid electrolyte layer. The thickness of the conductive carbon layer is 5~10 nm.

[0038] This invention provides a method for preparing the high-capacity lithium-rich manganese-based cathode material described in the above technical solution, comprising the following steps:

[0039] S1: Modify the gas-solid interface of the lithium-rich manganese-based cathode matrix material to obtain a lithium-rich manganese-based cathode material with oxygen vacancies.

[0040] S2: Mix the lithium-rich manganese-based cathode material with oxygen vacancies with water or an organic solvent, add Al(OH)3 colloid, stir evenly, and obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0041] S3: The lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface is mixed with a solid electrolyte precursor or solid electrolyte and then ultrasonically dispersed to obtain a gel-state composite.

[0042] S4: The gel-state composite is permeated and tempered at 180~200℃ and 2~5MPa to obtain a high-capacity lithium-rich manganese-based cathode material.

[0043] This invention modifies a lithium-rich manganese-based cathode substrate material through a gas-solid interface to obtain a lithium-rich manganese-based cathode material with oxygen vacancies. In this invention, the lithium-rich manganese-based cathode substrate material is preferably prepared according to the following method:

[0044] Nickel salt, cobalt salt, and manganese salt are mixed to obtain a mixed salt solution;

[0045] The mixed salt solution, precipitant, and complexing agent were co-precipitated to obtain a nickel-cobalt-manganese precursor suspension.

[0046] The nickel-cobalt-manganese precursor suspension was washed, filtered, and dried to obtain nickel-cobalt-manganese precursor particles.

[0047] The nickel-cobalt-manganese precursor particles and lithium source were mixed and sintered to obtain a lithium-rich manganese-based cathode matrix material.

[0048] The precipitant used in this invention is selected from sodium carbonate solution, sodium hydroxide solution, or sodium acetate solution; the complexing agent is an ammonia solution; the dropping rate of the mixed salt solution is 0.5~100 mL / min, specifically 0.5 mL / min, 5 mL / min, 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, or 100 mL / min; the dropping rate of the complexing agent is 0.1~40 mL / min, specifically 0.1 mL / min, 1 mL / min, 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, 35 mL / min, or 40 mL / min; the reaction pH value of the reactor is controlled to be 7.6~9.5 by controlling the dropping rate of the precipitant, specifically 7.6, 8.0, 8.5, 9, or 9.5. The temperature of the coprecipitation reaction is 50~60℃, specifically 50℃, 55℃ or 60℃; the time is 40~60h, specifically 40h, 45h, 50h, 55h or 60h; the coprecipitation is carried out under stirring conditions, and the stirring rate is 200~1000rpm.

[0049] The composition of the nickel-cobalt-manganese precursor varies depending on the type of precipitant used in this invention; if the precipitant is sodium carbonate, the composition of the nickel-cobalt-manganese precursor is Mn. c0 Ni a0 Co b0 CO3; if the precipitant is sodium hydroxide, then the composition of the nickel-cobalt-manganese precursor is Mn c0 Ni a0 Co b0 (OH)2; if the precipitant is sodium acetate, then the composition of the nickel-cobalt-manganese precursor is Mn c0 Ni a0 Co b0 (COOH)2. In a specific embodiment of the present invention, the chemical formula of the manganese-rich carbonate precursor particles is Ni. 0.167 Co 0.167 Mn 0.666 CO3.

[0050] In this invention, the lithium source is selected from one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, and lithium oxide. The lithium source is mixed with a nickel-cobalt-manganese mixture in a molar ratio of 1.45:1. The sintering temperature is 800~1000℃, and the sintering time is 14~20h. In a specific embodiment, the sintering temperature is 900℃, and the time is 16h.

[0051] In this invention, during the precursor co-precipitation process, nickel, cobalt, and manganese elements encounter the precipitant and undergo thick precipitation and crystallization to form primary particles. These primary particles then agglomerate into secondary spheres under stirring.

[0052] This invention modifies the prepared lithium-rich manganese-based cathode substrate material through a gas-solid interface. The gas-solid interface modification is performed in an NH3 / Ar mixed gas. The treatment temperature is 250~350℃, specifically 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, or 350℃. The treatment time is 1.5~2.5h, specifically 1.5h, 2h, or 2.5h. After gas-solid modification, oxygen vacancies are formed on the surface, improving the initial efficiency and yielding a lithium-rich manganese-based cathode material with oxygen vacancies that effectively suppresses lattice oxygen evolution and gas production.

[0053] After obtaining the lithium-rich manganese-based cathode material with oxygen vacancies, the present invention mixes the lithium-rich manganese-based cathode material with oxygen vacancies with water or an organic solvent, adds Al(OH)3 colloid, and stirs evenly to obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0054] In this invention, the mass ratio of the lithium-rich manganese-based cathode material with oxygen vacancies to water or an organic solvent is 1:(1.9~2.2), preferably 1:2; the organic solvent is ethanol. The mass ratio of the lithium-rich manganese-based cathode material with oxygen vacancies to Al(OH)3 colloid is 100~50:1. In this invention, the temperature is raised to 40°C while stirring until homogeneous, resulting in a lithium-rich manganese-based cathode material with an Al(OH)3 coating on its surface.

[0055] This invention involves mixing a lithium-rich manganese-based cathode material with an Al(OH)3 coating on its surface with a solid electrolyte precursor or a solid electrolyte, followed by ultrasonic dispersion to obtain a gel-like composite. The solid electrolyte in this invention can be a commercially available product or prepared using methods disclosed in existing technology; for example, the solid electrolyte is Li... 1.3 Al 0.3 Ti 1.3 P3O 12 (LATP) solid electrolyte, the related elements of which include phosphoric acid, lithium hydroxide, Al(OH)3 and tetrabutyl titanate; or the solid electrolyte is Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) Nano Solid Electrolyte.

[0056] In this invention, the content of the solid electrolyte precursor or solid electrolyte accounts for 0.45~0.55 wt% of the lithium-rich manganese-based cathode matrix material, and the content is 0.5 wt% in a specific embodiment.

[0057] If the solid electrolyte is selected from oxide solid electrolytes and / or halide solid electrolytes, the lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface, conductive carbon, solid electrolyte precursor or solid electrolyte are mixed and ultrasonically dispersed to obtain a gel-state composite; the conductive carbon includes one or more of graphene, carbon nanotubes and conductive carbon black.

[0058] The present invention permeates and tempers the gel-state composite at 180~200℃ and 2~5MPa to obtain a high-capacity lithium-rich manganese-based cathode material.

[0059] The present invention preferably uses a high-pressure permeation treatment in a high-pressure reactor; the high-pressure permeation temperature is 180~200℃, specifically 180℃, 190℃, or 200℃; the pressure is 2~5MPa, specifically 2 MPa, 3 MPa, 4 MPa, or 5 MPa. The permeation treatment time is 22~28h, specifically 22h, 23h, 24h, 25h, 26h, 27h, or 28h.

[0060] This invention involves annealing the permeation-treated material under a nitrogen atmosphere; the annealing temperature is 550~650℃, specifically 550℃, 600℃, or 650℃; the annealing time is 110~130min, specifically 110min, 120min, or 130min. Through annealing, this invention forms an Al2O3 layer and a solid electrolyte layer coating structure on the surface of the secondary particles and the surface of the internal primary particles; or an Al2O3 layer-solid electrolyte layer-conductive carbon layer coating structure.

[0061] This invention provides a battery comprising a positive electrode, a negative electrode, and a solid electrolyte;

[0062] The positive electrode sheet includes the high-capacity lithium-rich manganese-based positive electrode material described in the above technical solution;

[0063] The negative electrode sheet includes a negative electrode active material, which is selected from one or more of graphite, artificial graphite, silicon carbide materials, lithium metal composite negative electrode and lithium carbon negative electrode materials;

[0064] The solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0065] The present invention preferably prepares a solid cathode sheet from a high-capacity lithium-rich manganese-based cathode material; the solid cathode sheet comprises a high-capacity lithium-rich manganese-based cathode material and Li3In in a mass ratio of 80:15:2.5:2.5. 0.7 Sc 0.3Cl6: conductive carbon black: polyetheretherketone. The above materials are ball-milled and mixed, then rolled with a porous aluminum mesh under an inert environment to obtain a solid positive electrode sheet.

[0066] The present invention preferably uses Li3In with a mass ratio of 98:1.5:0.5. 0.7 Sc 0.3 Cl6, conductive carbon black and polyetheretherketone are ball-milled and mixed, and then calendered to form an electrolyte electrode film on the positive side.

[0067] The present invention preferably uses Li in a mass ratio of 98:1.5:0.5. 5.8 PS 4.8 Cl 1.2 Conductive carbon black and polyether ether ketone are ball-milled and mixed, then calendered to form an electrolyte electrode film on the negative electrode side.

[0068] The present invention preferably involves coarsely grinding lithium powder, indium powder and tin powder in a molar ratio of 5:3:2 under an inert atmosphere, then heating to 250°C and holding for 3 hours under an inert argon atmosphere, stirring evenly during the process, pouring the heated mixture onto a microporous copper foil, smoothing it, and then rolling it to obtain a solid negative electrode sheet.

[0069] This invention comprises stacking a lithium-rich manganese-based cathode material solid cathode sheet, a high-voltage electrolyte membrane on the cathode side, a solid electrolyte membrane layer on the anode side, and a lithium metal composite anode in sequence, and then encapsulating it under a pressure of 20 MPa to form a solid-state battery.

[0070] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a high-capacity lithium-rich manganese-based cathode material, its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0071] Preliminary Example:

[0072] 1) Prepare a 500L mixed salt solution of 2mol / L by mixing nickel sulfate, cobalt sulfate and manganese sulfate compounds in a molar ratio of 1:1:4.

[0073] 2) Prepare a 2 mol / L sodium carbonate solution as a precipitant and a 0.5 mol / L ammonia solution as a complexing agent;

[0074] 3) The mixed salt solution, precipitant, and complexing agent are added to the coprecipitation reactor at a certain rate using a metering pump. The dropping rate of the mixed salt solution is 30 mL / min, and the dropping rate of the complexing agent is 7 mL / min. The pH value of the reaction in the reactor is controlled to be around 8.5 by controlling the dropping rate of the precipitant. At the same time, the temperature of the reactor is controlled to be 55℃, and the stirring speed is 750 r / min. After the coprecipitation reaction is carried out for 45 h, a nickel-cobalt-manganese carbonate suspension is obtained.

[0075] 4) The above-mentioned nickel-cobalt-manganese carbonate suspension is washed, filtered, and dried to obtain a manganese-rich carbonate precursor; the chemical formula of the manganese-rich carbonate precursor is Ni 0.167 Co 0.167 Mn 0.666 CO3;

[0076] 5) Ni, a manganese-rich carbonate precursor 0.167 Co 0.167 Mn 0.666 CO3 and lithium carbonate were mixed in a solid phase at a molar ratio of Li:Me(Mn+Ni+Co)=1.45:1 and sintered at 900℃ for 16 h to obtain a lithium-rich manganese-based cathode substrate material.

[0077] Example 1

[0078] A high-capacity lithium-rich manganese-based cathode material for solid-state batteries includes the following steps:

[0079] Gas-solid interface modification of cathode materials:

[0080] The lithium-rich manganese-based cathode matrix material prepared in the above preliminary example was placed in a gas-solid interface reactor and treated at 300°C for 2 hours in an NH3 / Ar mixed gas to obtain a lithium-rich manganese-based cathode material with oxygen vacancies.

[0081] Cathode material coating:

[0082] 100g of the lithium-rich manganese-based cathode material powder with oxygen vacancies was dispersed in 200g of ethanol, and then 1g of Al(OH)3 colloid was added to it. The mixture was heated to 40°C and stirred until homogeneous to obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0083] Continue adding 1g of phosphoric acid (85 wt.%) and stirring until homogeneous; then add 1.17g of lithium hydroxide, 0.5g of Al(OH)3 and 8.61g of tetrabutyl titanate, and stir at 40℃ for 6h to obtain a black suspension containing lithium titanium aluminum phosphate precursor, wherein the lithium titanium aluminum phosphate precursor is 0.5 wt.% of lithium-rich manganese-based cathode matrix material; the black suspension is ultrasonically dispersed to form a gel-state complex;

[0084] High-pressure permeation treatment of cathode materials

[0085] The gel-like composite was placed in a high-pressure reactor and treated at 180℃ and 3MPa for 24 hours to allow the coating components to penetrate into the interior of the secondary spheres along the pores.

[0086] Tempering treatment of cathode materials

[0087] The above materials were annealed at 600°C for 2 hours under a nitrogen atmosphere to form a high-capacity lithium-rich manganese-based cathode material for solid-state batteries with an inner Al2O3 (2~5nm) + outer LATP (3~8nm) coating structure on both the surface of the secondary particles and the surface of the inner primary particles.

[0088] Solid-state positive electrode preparation:

[0089] The above solid-state battery uses a high-capacity lithium-rich manganese-based cathode material, according to the lithium-rich material: Li3In 0.7 Sc 0.3 Cl6: conductive carbon black: polyetheretherketone (PEEK) = 80:15:2.5:2.5 parts by mass was ball-milled. The ball milling speed was 600 r / min; the time was 5 h; and it was then rolled with a porous aluminum mesh in an inert environment.

[0090] Preparation of electrolyte film on the positive electrode side:

[0091] A method for preparing a high-voltage electrolyte membrane on the positive electrode side, wherein Li3In is subjected to an inert atmosphere. 0.7 Sc 0.3 Cl6: conductive carbon black: polyether ether ketone = 98:1.5:0.5 parts by mass were ball-milled and then calendered to obtain a 50μm film.

[0092] Preparation of electrolyte film on the negative electrode side:

[0093] The solid electrolyte membrane on the negative electrode side was prepared as follows, under an inert atmosphere in Li 5.8 PS 4.8 Cl 1.2 Conductive carbon black and polyetheretherketone (PEEK) in a ratio of 98:1.5:0.5 parts by mass were ball-milled and then calendered to form a film. A 50 μm electrolyte membrane was obtained on the negative electrode side.

[0094] Solid-state negative electrode preparation:

[0095] Li 0.5 In 0.3 Sn 0.2 The metal composite anode is prepared as follows: lithium powder, indium powder and tin powder are coarsely ground in a molar ratio of 5:3:2, then heated to 250°C and held for 3 hours under an inert argon atmosphere, with stirring to ensure uniformity. The heated material is then poured onto a microporous copper foil, leveled, and then rolled into shape.

[0096] Solid-state battery manufacturing

[0097] The lithium-rich manganese-based cathode material solid cathode sheet, the high-voltage electrolyte membrane on the cathode side, the solid electrolyte membrane layer on the anode side, and the metal composite anode are stacked sequentially and then encapsulated under a pressure of 20 MPa.

[0098] Performance testing:

[0099] The electrochemical performance is as follows: Within a voltage window of 1.4–4.2 V and a current density of 0.1 C, the specific capacity of the battery during the first discharge increased from 152.98 mAh / g in Comparative Example 1 to 250 mAh / g, and the initial efficiency also improved from 58.5% to 79.5%. Furthermore, the polarization voltage was reduced. The dV / dQ curve of the first charge of the lithium-rich manganese-based solid-state battery shows a reduction in oxidation potential, indicating a decrease in battery impedance. During 0.1 C cycling, the highest capacity of the high-capacity lithium-rich manganese-based cathode material reached as high as 250 mAh / g. After 100 cycles, the specific capacity also increased from 99.45 mAh / g in Comparative Example 1 to 223.84 mAh / g. The capacity retention rate also improved significantly, from 62.8% to 89.48%.

[0100] Example 2

[0101] The difference from Example 1 is as follows:

[0102] Cathode material coating:

[0103] Based on lithium-rich manganese-based cathode matrix material, 0.25 wt.% graphene and 0.25 wt.% carbon nanotubes (i.e. 0.25 g graphene and 0.25 g carbon nanotubes) were added to the black suspension containing lithium titanium aluminum phosphate precursor, and ultrasonically dispersed to form a gel-like composite with graphene and carbon nanotubes coated on the surface.

[0104] Tempering treatment of cathode materials

[0105] The above-mentioned gel-state composite was annealed at 550°C for 2 hours under a nitrogen atmosphere to form a high-capacity lithium-rich manganese-based cathode material for solid-state batteries with an inner layer of Al2O3 (2~5nm), a middle layer of LATP (3~8nm), and an outer layer of conductive carbon (5~10nm) covering the surface of the secondary particles and the surface of the inner primary particles.

[0106] Performance testing:

[0107] The electrochemical performance is as follows: Within a voltage window of 1.4–4.2 V and a current density of 0.1 C, the initial discharge specific capacity of the above battery increased from 152.98 mAh / g in Comparative Example 1 to 240 mAh / g, and the initial efficiency also improved from 58.5% to 79.5%. Furthermore, the polarization voltage was reduced. The dV / dQ curves of the first charge of the lithium-rich manganese-based solid-state battery show a reduction in oxidation potential, indicating a decrease in battery impedance. In 0.1 C cycling, the highest capacity of the lithium-rich material reached 245 mAh / g, and in 1 C cycling, the highest capacity of the lithium-rich manganese-based cathode material reached 225 mAh / g, demonstrating improved rate performance. After 100 cycles, the specific capacity also increased from 99.45 mAh / g in Comparative Example 1 to 228.18 mAh / g. The capacity retention also improved significantly, from 62.8% to 88.5%.

[0108] Example 3

[0109] The difference from Example 1 is that:

[0110] Cathode material coating:

[0111] Take 100g of the above-mentioned lithium-rich manganese-based cathode material powder with oxygen vacancies and disperse it in 200g of ethanol. Then add 1g of Al(OH)3 colloid to it, and stir evenly while heating to 40℃ to obtain lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0112] 0.5 g of Li was added to the above-mentioned lithium-rich manganese-based cathode material with Al(OH)3 coating. 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) nano-solid electrolyte, ultrasonically dispersed to form a gel-like complex;

[0113] Tempering treatment of cathode materials

[0114] The above-mentioned gel-state composite was annealed at 600°C for 2 hours under a nitrogen atmosphere to form a high-capacity lithium-rich manganese-based cathode material for solid-state batteries with an inner Al2O3 (2-5nm) + outer LLZTO (3-8nm) coating structure on both the surface of the secondary particles and the surface of the inner primary particles.

[0115] Performance testing:

[0116] The electrochemical performance is as follows: Within a voltage window of 1.4–4.2 V and a current density of 0.1 C, the initial discharge specific capacity of the above battery increased from 152.98 mAh / g in Comparative Example 1 to 235 mAh / g, and the initial efficiency also improved from 58% to 76.5%. Furthermore, the polarization voltage was reduced. The dV / dQ curve of the first charge of the lithium-rich manganese-based solid-state battery shows a reduction in oxidation potential, indicating a decrease in battery impedance. During 0.1 C cycling, the highest capacity of the lithium-rich manganese-based cathode material reached as high as 246 mAh / g. After 100 cycles, the specific capacity also increased from 99.45 mAh / g in Comparative Example 1 to 213.32 mAh / g. The capacity retention rate also improved significantly, from 62.8% to 90%.

[0117] Example 4

[0118] The difference from Example 3 is that:

[0119] Cathode material coating:

[0120] Take 100g of the above-mentioned lithium-rich manganese-based cathode material powder with oxygen vacancies and disperse it in 200g of ethanol. Then add 1g of Al(OH)3 colloid to it, and stir evenly while heating to 40℃ to obtain lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0121] 0.5 g of Li was added to the above-mentioned lithium-rich manganese-based cathode material with Al(OH)3 coating. 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) nano-solid electrolyte, ultrasonically dispersed to form a gel-like complex;

[0122] Based on the mass of the lithium-rich manganese-based cathode matrix material, 0.25 wt.% graphene and 0.25 wt.% carbon nanotubes (i.e., 0.25 g graphene and 0.25 g carbon nanotubes) were added to the above gel composite and ultrasonically dispersed to form a gel composite.

[0123] Tempering treatment of cathode materials:

[0124] The above materials were annealed at 600℃ for 2 hours under a nitrogen atmosphere to form a high-capacity lithium-rich manganese-based cathode material for solid-state batteries. This material has a coating structure consisting of an inner Al₂O₃ layer (2-5 nm), a middle LLZTO layer (3-8 nm), and an outer conductive carbon layer (5-10 nm) on both the surface of the secondary particles and the surface of the internal primary particles. Performance testing:

[0125] The electrochemical performance is as follows: Within a voltage window of 1.4–4.2 V and a current density of 0.1 C, the initial discharge specific capacity of the battery increased from 152.98 mAh / g in Comparative Example 1 to 235 mAh / g, and the initial efficiency also improved from 58.5% to 76.5%. Furthermore, the polarization voltage was reduced. The dV / dQ curves of the first charge of the lithium-rich manganese-based solid-state battery show a reduction in oxidation potential, indicating a decrease in battery impedance. During 0.1 C cycling, the highest capacity of the lithium-rich manganese-based cathode material reached 238 mAh / g, and during 1 C cycling, the highest capacity reached 218 mAh / g, demonstrating improved rate performance. After 100 cycles, the specific capacity increased from 99.45 mAh / g in Comparative Example 1 to 213.82 mAh / g. The capacity retention also significantly improved, from 62.8% to 88.2%.

[0126] Comparative Example 1

[0127] The difference from Example 1 is that high-pressure permeation was not performed;

[0128] Gas-solid interface modification of cathode materials:

[0129] The lithium-rich manganese-based cathode matrix material prepared in the above preliminary example was placed in a gas-solid interface reactor and treated at 300°C for 2 hours in an NH3 / Ar mixed gas to obtain a lithium-rich manganese-based cathode material with oxygen vacancies.

[0130] Cathode material coating:

[0131] 100g of the lithium-rich manganese-based cathode material powder with oxygen vacancies was dispersed in 200g of ethanol, and then 1g of Al(OH)3 colloid was added to it. The mixture was heated to 40°C and stirred until homogeneous to obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface.

[0132] Continue adding 1g of phosphoric acid (85 wt.%) and stirring until homogeneous; then add 1.17g of lithium hydroxide, 0.5g of Al(OH)3 and 8.61g of tetrabutyl titanate, and stir at 40℃ for 6h to obtain a black suspension containing lithium titanium aluminum phosphate precursor, wherein the lithium titanium aluminum phosphate precursor is 0.5 wt.% of lithium-rich manganese-based cathode matrix material; the black suspension is ultrasonically dispersed to form a gel-state complex;

[0133] Tempering treatment of cathode materials:

[0134] The above-mentioned gel-state composite was annealed at 600°C for 2 hours under a nitrogen atmosphere to form a high-capacity lithium-rich manganese-based cathode material for solid-state batteries with a secondary particle surface having an inner layer of Al2O3 (2~5nm) + an outer layer of LATP (3~8nm).

[0135] Performance testing:

[0136] The electrochemical performance is as follows: Under a voltage window of 1.4~4.2V and a current density of 0.1C, the first discharge specific capacity of the above battery is 152.98mAh / g, with an initial efficiency of 58.5%. After 100 cycles, the specific capacity is 99.45mAh / g, meaning the capacity retention rate is 62.8%. Because effective coating is only formed on the surface of the material, and the pores inside the secondary spheres, i.e., the surface of the primary particles, are not effectively coated, the material does not form a continuous ion / electron dual-conductivity network. The inability to form chemical bonds between the coating layer and the substrate results in greater resistance to lithium ion transport inside the particles, making it difficult for lithium ions to directly pass into the particles, thus leading to lower capacity performance.

[0137] As can be seen from the above embodiments, this invention generates oxygen vacancies through gas-solid interface reaction, and simultaneously coats the material surface, the internal pores of the secondary spheres, and the surface of the primary particles through surface coating using a combination of wet coating and high-pressure nano-infiltration, combined with high-temperature tempering; forming a continuous ion / electron dual-conductivity network; and using a high-capacity lithium-rich manganese-based cathode material for solid-state batteries with chemical bonding between the coating layer and the substrate to enhance interface stability. This significantly reduces the resistance to lithium-ion transport within the particles, allowing lithium ions to directly penetrate the particles, resulting in excellent capacity utilization. Furthermore, the addition of a conductive agent improves rate performance.

[0138] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-capacity lithium-rich manganese-based cathode material, characterized in that, The high-capacity lithium-rich manganese-based cathode material is prepared from lithium-rich manganese-based precursors and consists of in-situ formed primary particles and secondary spherical particles, the surfaces of which are coated with a coating layer. The coating layer includes an alumina layer and a solid electrolyte layer.

2. The high-capacity lithium-rich manganese-based cathode material according to claim 1, characterized in that, The particle size of the primary particles is 20~500nm; The particle size of the secondary spherical particles is 200 nm to 100 μm.

3. The high-capacity lithium-rich manganese-based cathode material according to claim 1, characterized in that, The solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

4. The high-capacity lithium-rich manganese-based cathode material according to claim 3, characterized in that, When the solid electrolyte is selected from oxide solid electrolytes and / or halide solid electrolytes, the coating layer further includes a conductive carbon layer disposed on the surface of the solid electrolyte layer.

5. The high-capacity lithium-rich manganese-based cathode material according to claim 4, characterized in that, The thickness of the alumina layer is 2~5 nm; The thickness of the solid electrolyte layer is 3~8 nm; The thickness of the conductive carbon layer is 5~10 nm.

6. A method for preparing the high-capacity lithium-rich manganese-based cathode material according to any one of claims 1 to 5, comprising the following steps: S1: Modify the gas-solid interface of the lithium-rich manganese-based cathode matrix material to obtain a lithium-rich manganese-based cathode material with oxygen vacancies. S2: Mix the lithium-rich manganese-based cathode material with oxygen vacancies with water or an organic solvent, add Al(OH)3 colloid, stir evenly, and obtain a lithium-rich manganese-based cathode material with Al(OH)3 coating on the surface. S3: The lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface is mixed with a solid electrolyte precursor or solid electrolyte and then ultrasonically dispersed to obtain a gel-state composite. S4: The gel-state composite is permeated and tempered at 180~200℃ and 2~5MPa to obtain a high-capacity lithium-rich manganese-based cathode material.

7. The preparation method according to claim 6, characterized in that, The tempering temperature is 500~700℃; the tempering time is 1~7h.

8. The preparation method according to claim 6, characterized in that, The lithium-rich manganese-based cathode material with Al(OH)3 coating on its surface, conductive carbon, solid electrolyte precursor or solid electrolyte are mixed and ultrasonically dispersed to obtain a gel-state composite. The conductive carbon includes one or more of graphene, carbon nanotubes, and conductive carbon black.

9. The preparation method according to claim 6, characterized in that, The gas-solid interface modification was performed in a mixture of NH3 and Ar at 250-350°C for 1.5-2.5 hours.

10. An all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte; The positive electrode sheet comprises the high-capacity lithium-rich manganese-based positive electrode material as described in any one of claims 1 to 5; The negative electrode sheet includes a negative electrode active material, which is selected from one or more of graphite, artificial graphite, silicon carbide materials, lithium metal composite negative electrode and lithium carbon negative electrode materials; The solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

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