Solid-state electrolyte integrated composite modified positive electrode material and application thereof in battery

Abstract

The application relates to a solid-state electrolyte integrated composite modified positive electrode material and application thereof in batteries, wherein the positive electrode material comprises a core and a shell coated on the outer surface of the core; the surface nanometer coating layer is a solid-state electrolyte; the positive electrode material is doped with an element M, which is enriched from the inside of the positive electrode material particles to the surface of the positive electrode material particles; when the composite modified positive electrode material is prepared, firstly, a solid-state electrolyte liquid phase reaction / spray drying granulation precursor solution is configured; then, ternary precursors and lithium source material powders are added into the solid-state electrolyte precursor solution to generate pre-sintered materials through liquid phase reaction or spray granulation methods; finally, the pre-sintered materials are subjected to sintering treatment to obtain the composite modified positive electrode material. The solid-state electrolyte integrated composite modified positive electrode material can control the positive electrode / solid-state electrolyte interface, effectively protect the positive electrode, improve the stability and interface compatibility of the positive electrode material, and thus improve the safety and service life of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium secondary liquid and solid-state batteries, and particularly relates to a solid electrolyte integrated composite modified cathode material and application thereof in batteries. Background Art

[0002] Lithium secondary batteries are widely used in 3C electronic products, new energy electric vehicles, smart grids, advanced energy storage equipment, unmanned aerial vehicles and even aerospace military industry due to their advantages such as high energy density and long cycle life. At present, the energy density and rate performance of commercial lithium secondary batteries cannot meet the iteration requirements of various products, which limits the performance of products. The main reason lies in that conventional commercial cathode materials, including lithium cobalt oxide LiCoO2, lithium iron phosphate LiFePO4, spinel lithium manganate LiMn2O4, and low- and medium-nickel ternary materials LiNi x Co y Mn 1-x-y O2(0≤x≤0.5, 0<y≤0.4, 0≤z≤0.4) have low specific energy. Increasing the proportion of nickel in ternary materials can greatly improve the specific energy of the material. When x≥0.9, the specific capacity of the ternary material can reach more than 200 mAh / g, which meets the iteration requirements of most products. However, the safety and stability of high-nickel ternary materials and their corresponding batteries are greatly reduced. The reasons are as follows: (1) During calcination and working cycle of the material, lithium ions and divalent nickel ions will have cation mixing, leading to abnormal structure mainly in the outer layer of the material, increased side reactions and impurity phases, which impair the cycle and safety performance of the material; (2) High-nickel materials have high electrochemical activity, and the interface part is prone to side reactions with electrolyte, leading to gas generation and formation of impurities, thereby affecting the comprehensive performance of the material. Therefore, modifying cathode materials by means of coating or doping and replacing traditional liquid batteries with solid-state batteries have become effective improvement solutions.

[0003] Some research and development teams use materials such as La2O3, TiO2, ZrO2, Al2O3, YPO4, Li3PO4, AlPO4, Li2TiO3, and MgO to coat high-nickel ternary cathode materials. Since the surface coating can effectively prevent redox side reactions between the cathode active material and the electrolyte at the interface and inhibit the growth of impurity phases, the structural stability and thermal safety of the material are improved. However, most surface coating layers are not formed by in-situ growth, and have poor compatibility with the surface of the cathode material. The surface coating layer is prone to falling off at high temperature or during long cycles, and most coating layers have low ionic conductivity, so rate performance cannot be balanced while improving the cycle and safety performance of the material. For example, Chinese Patent CN105914356A discloses an invention that mainly improves the stability and cycle performance of the ternary material by coating alumina on the surface of the material, but the ionic conductivity of alumina is low, and the rate performance of the material cannot be balanced.

[0004] Doping can stabilize the material structure by suppressing transition metal migration and lattice oxygen precipitation from within the material. However, elemental doping cannot effectively modify the material surface and cannot completely solve the interface problem between high-nickel materials and electrolytes. For example, Chinese patent CN102610806B uses inert elements to dope lithium cobalt oxide. Inert elements can stabilize the particle structure, giving lithium cobalt oxide materials good cycle performance under high voltage. However, the method provided by this patent can only modify the interior of the particles and cannot improve the interface stability and compatibility of the cathode material / electrolyte.

[0005] Solid-state batteries are composed primarily of solid materials, with the solid electrolyte serving as both a lithium-ion transport medium and a separator. This significantly reduces the likelihood of side reactions with the high-nickel cathode. Furthermore, even if one module of a solid-state battery experiences a puncture or breakage, the absence of leakage prevents the use of other modules, making it the optimal solution for completely addressing the safety issues of high-energy-density lithium-ion rechargeable batteries. However, poor interfacial compatibility between the cathode and the solid electrolyte can lead to phenomena such as a space charge layer and loose contact between the cathode and solid electrolyte materials. This ultimately results in a surge in interfacial impedance, deterioration of the cathode structure, and problems such as low battery life, thermal runaway, and susceptibility to short circuits. All the aforementioned modification schemes have drawbacks, and a comprehensive and universal modification scheme that can overcome these shortcomings is urgently needed. The deficiencies of coating and doping modification schemes can be addressed by combining integrated surface coating with gradient doping.

[0006] The inventor filed a patent for this solution in 2022, with patent application number 202211278871.0. In response to the problem of poor compatibility between solid electrolyte and cathode interface, the inventor innovatively proposed to use solid electrolyte to modify cathode material, thereby improving both cathode material and the compatibility between cathode material and solid electrolyte interface. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an integrated solid electrolyte composite modified cathode material and its application in batteries.

[0008] The technical solution adopted in this invention is: a solid electrolyte integrated composite modified cathode material, comprising a composite modified core and a shell covering the core, the shell being a nano-coating layer formed by the solid electrolyte; the cathode material is doped with element M, and the concentration of doped element M varies in a gradient from the inside of the cathode material particle to the surface of the cathode material particle, eventually becoming enriched on the surface; wherein, element M is aluminum, magnesium, sodium, titanium, zirconium or boron.

[0009] Preferably, the chemical formula for the cathode material is LiNi. x Co y Mn z Ma O2, 0.6≤x≤1, 0 <y≤0.4,0≤z≤0.4;

[0010] The general molecular formula of the nano-coating layer formed by the solid electrolyte is AMO3,AM1M2P3O 12 or Li5La3M2O 12 ;

[0011] A represents lithium, sodium, potassium, silver, hydrogen, magnesium, calcium, copper, nickel, manganese, cobalt, zinc, or aluminum ions.

[0012] The preparation method of the solid electrolyte integrated composite modified cathode material includes the following specific steps:

[0013] Step 1: Prepare the precursor solution for the solid electrolyte;

[0014] Step 2: Add the ternary precursor and lithium source to the precursor solution, and generate the pre-sintered material through liquid phase reaction or spray granulation method;

[0015] Step 3: Sinter the pre-sintered material to obtain a solid electrolyte integrated composite modified cathode material.

[0016] Preferably, in step one, the solid electrolyte material has the general molecular formula LiX, ABX3, AMO3, AM1M2P3O 12 Li5La3M2O 12 Where A, B, and M are metallic elements, and X is oxygen or a halogen element; A and B are lithium, sodium, potassium, silver, hydrogen, magnesium, calcium, copper, nickel, manganese, cobalt, zinc, or aluminum ions. To prepare the precursor solution, first add the solid raw material from the solid electrolyte raw material to the solvent and stir until completely dissolved. Then add the liquid raw material to the mixture and stir until homogeneous. Dry the solution for a period of time, from 30 minutes to 3 hours, to evaporate the solvent and bring the concentration of the solid electrolyte raw material in the precursor solution to a specific range. Continue stirring to obtain the precursor solution.

[0017] Preferably, when adding solid raw materials to the solvent, the stirring speed is 200-500 rpm and the solution temperature is 25℃-60℃; when adding liquid raw materials to the mixture, the stirring speed is 400-700 rpm and the solution temperature is 25℃-60℃; when stirring again after drying, the stirring speed is 500-800 rpm, the solution temperature is 50℃-70℃, and the time is 30-90 minutes.

[0018] Preferably, the temperature during the stirring process is controlled by an oil bath or a water bath.

[0019] Preferably, in step two, the chemical formula of the high-nickel ternary cathode material precursor is Ni x Co y Mn 1-x-y(OH)₂, where 0.6 ≤ x ≤ 1, 0 <y≤0.4;

[0020] The lithium source is one of lithium carbonate, lithium hydroxide, or lithium oxide.

[0021] Preferably, in step two, the ternary precursor and lithium source are added to the precursor solution and stirred according to a set procedure. Specifically, in the first stage, the stirring speed is 200-500 rpm, the solution temperature is 40℃-60℃, and the stirring time is 30-60 min; in the second stage, the stirring speed is 400-700 rpm, the solution temperature is 50℃-80℃, and the stirring time is 60-120 min; in the third stage, the stirring speed is 500-900 rpm, the solution temperature is 60℃-90℃, and the stirring time is 100-180 min; finally, a suspension that meets the conditions for liquid-phase reaction / spray drying granulation is obtained.

[0022] Preferably, the suspension is processed through a stepped modular liquid-phase reaction / spray granulation process, specifically:

[0023] The stirring speed in the first stage is 300-600 rpm, the solution temperature is 50-65℃, and the stirring time is 60-80 min.

[0024] The second stage involves a stirring speed of 500-800 rpm, a solution temperature of 60-90℃, and a stirring time of 90-135 min.

[0025] In the third stage of the process, liquid phase stirring and evaporation are continued at a stirring speed of 500-900 rpm, a solution temperature of 70-110℃, and a stirring time of 120-540 min.

[0026] In the final stage of the process, continue liquid-phase stirring at a speed of 300-500 rpm and a solution temperature of 70-110℃ until the suspension becomes a mud-like or colloidal pre-sintered material.

[0027] or,

[0028] The stirring speed in the first stage is 300-600 rpm, the solution temperature is 50-65℃, and the stirring time is 60-80 min.

[0029] The second stage involves a stirring speed of 500-800 rpm, a solution temperature of 60-90℃, and a stirring time of 90-135 min.

[0030] In the third stage of the process, the liquid phase is kept under stirring at a speed of 500 rpm, and the suspension is connected to the spray drying / fluidized bed equipment.

[0031] The final stage of the process involves spray drying / fluidized bed granulation. The characteristic parameters of this process are: the mass ratio of solids to solvent in the suspension is 1-15, the nozzle diameter is 0.1-20 mm, the granulation temperature is 80-350℃, the raw material pump speed is 5-100 ml / min, and the hot air pressure in the reaction vessel is 0.15-3 MPa, ultimately yielding a pre-sintered material.

[0032] Preferably, the pre-sintered material is subjected to gradient high-temperature sintering; the sintering process includes preliminary heat treatment, intermediate heat treatment, and final heat treatment in sequence. The preliminary heat treatment process is: heat treatment at 250-450℃ for 0-5 hours, the intermediate heat treatment process is: heat treatment at 500-700℃ for 2-9 hours, and the final heat treatment process is: heat treatment at 700-1000℃ for 6-18 hours.

[0033] A battery comprising a solid electrolyte integrated composite modified cathode material;

[0034] Preferably, the battery is a lithium secondary battery or a lithium solid-state battery.

[0035] The advantages and positive effects of this invention are: by modifying and regulating, the surface alkalinity of the high-nickel ternary cathode material is reduced, the electrochemical and safety performance is significantly enhanced, and the interfacial stability and compatibility between the material and the solid electrolyte are improved; by using a solid electrolyte to perform integrated and comprehensive composite modification of the cathode material, the purpose of effectively modifying the cathode material, improving its intrinsic properties and stability, and regulating the interfacial compatibility between the cathode and the solid electrolyte is achieved by using a suitable solid electrolyte coating layer.

[0036] The entire modification process can be shortened to three steps, eliminating the need to add dopants during precursor preparation or redesign precursor preparation parameters. Commercial precursor products can be used for modification. The staged stirring method promotes complete reaction. Therefore, the process of this invention is simple, low-cost, and the process conditions are easy to control. Attached Figure Description

[0037] Figure 1 SEM images of the materials in the control example and Example 1;

[0038] Figure 2 SEM images of the materials in the control example and Example 2;

[0039] Figure 3 Cycle data of batteries from Examples 1 and 2 and comparative materials were compared.

[0040] Figure 4 Differential scanning calorimetry (DSC) test data of the fully charged materials in Examples 1, 2 and the comparative examples;

[0041] Figure 5 Photographs of lithium metal pouch cells using the materials of Example 1 and Example 2 that passed the nail penetration test. Detailed Description of Embodiments

[0042] Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings.

[0043] The present invention relates to a solid electrolyte integrated composite modified positive electrode material and application thereof in a battery. By combining construction of a nano-protective layer on the material surface and gradient doping modification of the material, the material after composite modification has a physical structure comprising an inner core and an outer shell coated on the outer surface of the inner core, and has a chemical formula of LiNi x Co y Mn z M a O2, wherein 0.6 ≤ x ≤ 1, 0 < y ≤ 0.4, 0 ≤ z ≤ 0.4, M is a doping element, the surface nano-coating layer is a solid electrolyte having a general molecular formula of AMO3, AM1M2P3O 12 or Li5La3M2O 12 . From the surface of the material particle to the interior of the material particle, the concentration of the doping element M changes in a gradient and is enriched on the surface. Wherein M can be one of aluminum, magnesium, sodium, titanium, zirconium and boron. A and B can be monovalent ions, divalent ions or trivalent ions, the +1 valent ions are lithium, sodium, potassium, silver or hydrogen ions; the +2 valent ions are magnesium, calcium, copper, nickel, manganese, cobalt or zinc ions; the +3 valent ions are aluminum ions.

[0044] When preparing the composite modified positive electrode material, firstly preparing a solid electrolyte precursor solution for liquid phase reaction / spray drying granulation; then adding a ternary precursor (a commercial ternary material precursor, the structural formula of the material is Ni x Co y Mn 1-x-y (OH)2, wherein 0.6 ≤ x ≤ 1, 0 < y ≤ 0.4, ) and lithium source material powder into the solid electrolyte precursor solution, stirring uniformly, then generating a pre-sintered material by a liquid phase reaction or spray granulation method; finally sintering the pre-sintered material to obtain the positive electrode material treated by the modification and interface regulation method.

[0045] Applying the solid electrolyte material to the modification design of the positive electrode material, combining the solid electrolyte with gradient doping and construction of the nano-coating layer, and innovatively coating the solid electrolyte material precursor solution on the surface layer of the ternary material precursor at the precursor stage, and generating the coating layer and gradient doping elements in situ by calcination, which not only reduces the surface residual alkali content of the ternary material, but also enables the coating layer and the material to form chemical bond bonding, improves the stability of the coating layer and enhances the modification effect; gradient doping improves the internal structural stability of the material, and as a modification material, the solid electrolyte can effectively improve the interface compatibility between the positive electrode and the solid electrolyte.

[0046] The specific methods for composite modification are as follows:

[0047] Step (1): According to requirements, dissolve the raw materials needed for the synthesis of solid electrolyte A in a suitable solvent B according to a certain molar ratio and addition coefficient, and stir according to the designed stirring process until all raw materials are dissolved to obtain the solid electrolyte liquid phase reaction / spray drying granulation precursor solution C. The molecular formula of material A is AMO3, AM1M2P3O 12 Li5La3M2O 12 Equal structure;

[0048] Among them, the general formula of solid electrolyte A is LiX, ABX3, AMO3, AM1M2P3O 12 Li5La3M2O 12 In this formula, A, B, and M are metallic elements, and X is an oxygen element or a halogen element. The raw materials for synthesizing A can be organic or inorganic raw materials, depending on the solvent and modification scheme requirements. The purity of all raw materials must be higher than 99.99%, and the water content of the raw materials used in organic solvents must be less than 300 ppm. The mass ratio of the raw materials for preparing solid electrolyte A to the high-nickel ternary material precursor should be 0.00-0.25. The standard addition amount of the raw materials for synthesizing solid electrolyte A should be determined according to the molar ratio of each element in the chemical formula of A. Considering the losses such as sedimentation, side reactions, volatilization, and hydrolysis in the liquid phase reaction, the addition amount of the raw materials for synthesizing A in step (1) can also be 1.05-10 times the standard addition amount, preferably 1.05-5 times.

[0049] Solvent B can be water or anhydrous ethanol or other organic reagents, with a water content of less than 100 ppm. The weight ratio of solvent B to the high-nickel ternary precursor is 3-30. When preparing solution C, first add solid raw material A to B, stirring at 200-500 rpm and at a solution temperature of 25-60°C. After the solid raw material is completely dissolved, add liquid raw material A to B, stirring at 400-700 rpm and at a solution temperature of 25-60°C. Stir until all raw materials are completely dissolved, then stir and dry. The stirring speed is 500-800 rpm, the solution temperature is 50-70°C, and the time is 30-90 minutes. Dry for 30 minutes to 3 hours. After the solvent evaporates, the concentration of solid electrolyte raw material in the precursor solution reaches a specific range. The heating method can be oil bath or water bath heating, depending on the properties of the solvent.

[0050] Step (2): Select a commercially available high-nickel ternary cathode material precursor with the chemical formula Ni x Co y Mn 1-x-y(OH)2, wherein 0.6≤x≤1 and 0<y≤0.4, pouring the precursor material and the lithium source for ternary material into the precursor solution C, and stirring and drying according to a certain process to obtain a suspension D that meets the conditions for liquid phase reaction / spray drying granulation;

[0051] The chemical formula of the commercial high-nickel ternary cathode material precursor is Ni x Co y Mn 1-x-y (OH)2, wherein 0.6≤x≤1 and 0<y≤0.4. The median particle size D of the commercial high-nickel ternary cathode material precursor 50 is 2-20 μm, for example, 2 μm, 4 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 20 μm, etc. Controlling the D of the precursor particle size 50 value is beneficial to improving the consistency of the material. If the particle size is too small, the specific surface area of the material will be too large, which increases the contact area between the cathode material and the electrolyte, and may reduce the electrochemical and safety performance of the cathode material; if the particle size is too large, the rate performance of the material will be reduced. The lithium source for the ternary material is one of lithium carbonate, lithium hydroxide or lithium oxide. Considering the additional loss during in-situ reaction and calcination sintering, the molar ratio of lithium element in the lithium source material to metal element in the ternary cathode material precursor is 1.05-1.15.

[0052] The process used for preparing suspension D is characterized in that the process is a step-wise stepped liquid phase stirring and volatilization process, and the heating method can be selected from oil bath or water bath heating according to the properties of the solvent. The specific process is as follows: the stirring speed in the first stage is 200-500 rpm, the solution temperature is 40-60°C, and the stirring time is 30-60 min; the stirring speed in the second stage is 400-700 rpm, the solution temperature is 50-80°C, and the stirring time is 60-120 min; the stirring speed in the third stage is 500-900 rpm, the solution temperature is 60-90°C, and the stirring time is 100-180 min.

[0053] Step (3): subjecting the suspension D to liquid phase reaction or spray drying granulation reaction according to a certain process to obtain pre-sintered

[0054] material E; the suspension is processed by a stepped modular liquid phase reaction / spray granulation process;

[0055] The liquid phase reaction process is specifically:

[0056] the stirring speed in the first stage is 300-600 rpm, the solution temperature is 50-65°C, and the stirring time is 60-80 min;

[0057] the stirring speed in the second stage is 500-800 rpm, the solution temperature is 60-90°C, and the stirring time is 90-135 min;

[0058] In the third stage of the process, liquid-phase stirring and volatilization are continued, with a stirring speed of 500-900 rpm, a solution temperature of 70-110°C, and a stirring time of 120-540 min;

[0059] In the final stage of the process, liquid-phase stirring is continued, with a stirring speed of 300-500 rpm, a solution temperature of 70-110°C, and stirring is continued until the suspension turns into a muddy or colloidal pre-sintered material;

[0060] Alternatively,

[0061] The spray granulation and fluidized bed process is specifically as follows:

[0062] In the first stage, the stirring speed is 300-600 rpm, the solution temperature is 50-65°C, and the stirring time is 60-80 min;

[0063] In the second stage, the stirring speed is 500-800 rpm, the solution temperature is 60-90°C, and the stirring time is 90-135 min;

[0064] In the third stage of the process, the liquid-phase stirring state is maintained, the stirring speed is 500 rpm, and the suspension is connected to spray drying / fluidized bed equipment;

[0065] The final stage of the process is granulation by spray drying / fluidized bed, and the characteristic parameters of the process are as follows: the mass ratio of solid to solvent in the suspension is 1-15, the nozzle diameter is 0.1-20 mm, the granulation temperature is 80-350°C, the raw material pump speed is 5-100 ml / min, the hot air pressure in the reaction tank is 0.15-3 MPa, and finally the pre-sintered material is obtained.

[0066] Step (4): subject the pre-sintered material E to gradient high-temperature sintering according to a specific process under a certain atmosphere condition. The sintering process is characterized by gradient high-temperature sintering, the sintering equipment is a box-type resistance furnace or a tube furnace, the sintering atmosphere is oxygen or air, and the sintering process sequentially includes preliminary heat treatment, intermediate heat treatment and final heat treatment. The preliminary heat treatment process is: heat treatment at 250°C-450°C for 0-5 h; the intermediate heat treatment process is: heat treatment at 500°C-700°C for 2 h-9 h; the final heat treatment process is: heat treatment at 700°C-1000°C for 6 h-18 h;

[0067] After sintering, cooling, crushing and screening are performed to obtain a product with a core of LiNi x Co y Mn z M a O2, 0.6≤x≤1, 0<y≤0.4, 0≤z≤0.4, M is a doping element, and the surface is a solid electrolyte (with a general molecular formula of AMO3, AM1M2P3O12 Li5La3M2O 12 A solid electrolyte integrated composite modified cathode material with nano-coating.

[0068] By selecting a suitable solid electrolyte, during the high-temperature sintering stage, partially gradient-doped M elements are allowed to grow radially along the precursor due to the chemical potential generated by the concentration gradient difference. The remaining precursor materials of the solid electrolyte material will react in situ with the residual alkali (sodium hydroxide and lithium carbonate) on the surface of the lithium source or precursor to generate a nanoscale solid electrolyte coating layer. The modification process is simple, low-cost, and easy to control. The modified material has reduced surface residual alkali, protects the material surface, improves internal structural stability, enhances the interface stability and compatibility of the cathode material / solid electrolyte, and improves cycle and safety performance. Utilizing the "surface residual alkali" generated during the high-temperature lithiation stage of the precursor, a nanoscale solid electrolyte surface coating layer is generated through in-situ reaction, reducing the surface residual alkali content of the cathode material and mitigating battery polarization. The in-situ nano-coating layer is chemically bonded to the material, exhibits good compatibility, is not easily detached during battery cycling, and does not undergo side reactions with the electrolyte or solid electrolyte, providing excellent protection for high-nickel ternary cathode materials.

[0069] The present invention will now be described with reference to the accompanying drawings. Experimental methods not specifically described in terms of operation steps are performed in accordance with the corresponding product manuals. Unless otherwise specified, the instruments, reagents, and consumables used in the embodiments can be purchased from commercial companies.

[0070] Example 1

[0071] Lithium titanium aluminum phosphate (LATP:LI) 1.3 AI 0.3 Ti 1.7 (PO4)3) Integrated Composite Modified Cathode Material Solution

[0072] The raw materials A required for the synthesis of LATP—0.5g lithium nitrate, 0.6g aluminum nitrate decahydrate, 2.65g isopropyl titanate, and 1.9g ammonium dihydrogen phosphate—were added separately to 150g of ethanol-water solvent B. The mixture was stirred according to the following procedure: First, solid material A was added to B at a stirring speed of 300 rpm and a solution temperature of 45°C until the solid raw materials were completely dissolved. Then, liquid material A was added to B at a stirring speed of 400 rpm and a solution temperature of 60°C until all raw materials were completely dissolved. The solution was then stirred and dried for a period of time at a stirring speed of 500 rpm and a solution temperature of 50°C for 30 minutes to obtain precursor solution C. The heating method used in the above process was oil bath heating.

[0073] A commercially available high-nickel ternary cathode material precursor was selected, with the precursor having the chemical formula Ni. 0.9 Co0.4 Mn 0.6 (OH)2, 20g of precursor material and 8.5g of lithium carbonate material are poured into precursor solution C, and stirred and dried according to the following process: the stirring speed in the first stage is 250 rpm, the solution temperature is 45℃, and the stirring time is 40 min; the stirring speed in the second stage is 700 rpm, the solution temperature is 80℃, and the stirring time is 120 min; the stirring speed in the third stage is 600 rpm, the solution temperature is 90℃, and the stirring time is 150 min, to obtain a suspension D that meets the requirements for liquid phase reaction. The above process uses oil bath heating.

[0074] The suspension D was subjected to a liquid-phase reaction according to the following process to obtain the pre-sintered material E: the first stage was a stirring speed of 600 rpm, a solution temperature of 65°C, and a stirring time of 70 min; the second stage was a stirring speed of 650 rpm, a solution temperature of 90°C, and a stirring time of 135 min; the third stage was a stirring speed of 850 rpm, a solution temperature of 100°C, and a stirring time of 400 min; the final stage was a stirring speed of 300 rpm, a solution temperature of 70°C, and stirring until the suspension D became a mud-like or colloidal pre-sintered material E. The above processes used oil bath heating.

[0075] The pre-sintered material E was subjected to gradient high-temperature sintering in a box-type resistance furnace under a pure oxygen atmosphere according to the following process: the sintering process consisted of preliminary heat treatment, intermediate heat treatment, and final heat treatment in sequence. The preliminary heat treatment was performed at 300℃ for 3 hours, the intermediate heat treatment was performed at 500℃ for 5 hours, and the final heat treatment was performed at 700℃ for 6 hours. After cooling, crushing, and sieving, the sintered material was obtained with a Li(Ni) core. 0.9 Co 0.4 Mn 0.6 ) 0.98 M 0.02 O2 and M are doped with Al and Ti elements, and the surface is a solid electrolyte integrated composite modified cathode material with a solid electrolyte lithium aluminum titanium phosphate (LATP) nano-coating layer.

[0076] Example 2

[0077] Tantalum-doped lithium lanthanum zirconium oxide (LLZTO: Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Integrated composite modified cathode material solution

[0078] Raw materials A required for the synthesis of LLZTO, namely 0.1 g of lithium nitrate hydrate, 1.2 g of lanthanum nitrate hydrate, 0.62 g of zirconium isopropoxide, and 0.25 g of tantalum ethoxide, were added to 165 g of ethanol-water solvent B. The mixture was stirred according to the following procedure: First, solid material A was added to B at a stirring speed of 300 rpm and a solution temperature of 40°C until the solid raw materials were completely dissolved. Then, liquid material A was added to B at a stirring speed of 450 rpm and a solution temperature of 55°C until all raw materials were completely dissolved. The solution was then stirred and dried for a period of time at a stirring speed of 500 rpm and a solution temperature of 55°C for 30 minutes to obtain precursor solution C. The heating method used in the above process was oil bath heating.

[0079] A commercially available high-nickel ternary cathode material precursor was selected, with the precursor having the chemical formula Ni. 0.9 Co 0.4 Mn 0.6 (OH)2, 20g of precursor material and 8.5g of lithium carbonate material are poured into precursor solution C, and stirred and dried according to the following process: the stirring speed in the first stage is 300 rpm, the solution temperature is 50℃, and the stirring time is 45 min; the stirring speed in the second stage is 650 rpm, the solution temperature is 75℃, and the stirring time is 110 min; the stirring speed in the third stage is 600 rpm, the solution temperature is 80℃, and the stirring time is 120 min, to obtain a suspension D that meets the requirements for liquid phase reaction. The above process uses oil bath heating.

[0080] The suspension D was subjected to a liquid-phase reaction according to the following process to obtain the pre-sintered material E: the first stage was a stirring speed of 500 rpm, a solution temperature of 55°C, and a stirring time of 80 min; the second stage was a stirring speed of 700 rpm, a solution temperature of 85°C, and a stirring time of 130 min; the third stage was a stirring speed of 800 rpm, a solution temperature of 95°C, and a stirring time of 350 min; the final stage was a stirring speed of 300 rpm, a solution temperature of 60°C, and stirring until the suspension D became a mud-like or colloidal pre-sintered material E. The above processes used oil bath heating.

[0081] The pre-sintered material E was subjected to gradient high-temperature sintering in a box-type resistance furnace under a pure oxygen atmosphere according to the following process: the sintering process consisted of preliminary heat treatment, intermediate heat treatment, and final heat treatment in sequence. The preliminary heat treatment was performed at 300℃ for 4 hours, the intermediate heat treatment was performed at 450℃ for 4 hours, and the final heat treatment was performed at 750℃ for 8 hours. After cooling, crushing, and sieving, the sintered material was obtained with a Li(Ni) core. 0.9 Co 0.4 Mn 0.6 ) 0.98 Zr 0.02O2 is an integrated composite modified cathode material with a solid electrolyte tantalum-doped lithium lanthanum zirconium oxide (LLZTO) nanocoating layer on its surface.

[0082] Comparative example:

[0083] 150g of ethanol aqueous solvent B was stirred according to the following process: stirring speed 300 rpm, solution temperature 45℃, stirring time 30 min; then increasing the stirring speed to 400 rpm, solution temperature 60℃, stirring time 30 min; finally, stirring speed 500 rpm, solution temperature 50℃, stirring time 30 min, to obtain precursor control solution C. The heating method in the above process was oil bath heating.

[0084] A commercially available high-nickel ternary cathode material precursor was selected, with the precursor having the chemical formula Ni. 0.9 Co 0.4 Mn 0.6 (OH)2, 20g of precursor material and 8.5g of lithium carbonate material are poured into precursor solution C, and stirred and dried according to the following process: the stirring speed in the first stage is 250 rpm, the solution temperature is 45℃, and the stirring time is 40 min; the stirring speed in the second stage is 700 rpm, the solution temperature is 80℃, and the stirring time is 120 min; the stirring speed in the third stage is 600 rpm, the solution temperature is 90℃, and the stirring time is 150 min, to obtain a suspension D that meets the requirements for liquid phase reaction. The above process uses oil bath heating.

[0085] The suspension D was subjected to a liquid-phase reaction according to the following process to obtain the pre-sintered material E: the first stage was a stirring speed of 600 rpm, a solution temperature of 65°C, and a stirring time of 70 min; the second stage was a stirring speed of 650 rpm, a solution temperature of 90°C, and a stirring time of 135 min; the third stage was a stirring speed of 850 rpm, a solution temperature of 100°C, and a stirring time of 400 min; the final stage was a stirring speed of 300 rpm, a solution temperature of 70°C, and stirring until the suspension D became a mud-like or colloidal pre-sintered material E. The above processes used oil bath heating.

[0086] The pre-sintered material E was subjected to gradient high-temperature sintering in a box-type resistance furnace under a pure oxygen atmosphere according to the following process: the sintering process consisted of preliminary heat treatment, intermediate heat treatment, and final heat treatment in sequence. The preliminary heat treatment was performed at 300℃ for 3 hours, the intermediate heat treatment was performed at 500℃ for 5 hours, and the final heat treatment was performed at 700℃ for 6 hours. After cooling, crushing, and sieving, the sintered material was obtained with the molecular formula LiNi. 0.9 Co 0.4 Mn 0.6 O2 is the control material.

[0087] Figure 3 This involves testing the electrical performance of batteries made using the materials from the control group and examples as positive electrodes. Poor coating schemes can lead to excessively thick or uneven coating layers, or poor contact with the positive electrode body, even with the negative electrode, separator, and electrolyte remaining unchanged. These defects can cause the battery's cycle performance to deteriorate compared to the uncoated control group. Test data shows that the batteries using the materials from Examples 1 and 2 as positive electrodes exhibit cycle performance similar to the control group, demonstrating that the coating scheme of this patent is well-designed, with a uniform and appropriately thick coating layer that is tightly bonded to the material, without compromising the battery's electrical performance.

[0088] Figure 4 Examples 1 and 2 demonstrate that they significantly improve the safety of the material. Figure 5 This demonstrates that batteries using the two safety-enhancing materials from Examples 1 and 2 as the positive electrode and lithium metal as the negative electrode exhibit significantly improved safety, as evidenced by passing a nail penetration test. Typically, batteries like the control group, using high-nickel materials as the positive electrode and lithium metal as the negative electrode, fail the nail penetration test, catching fire and exploding during the process. Therefore, the improvement in material safety is the core difference between this patent and the previous patent. The previous patent's coating method did not demonstrate any improvement in safety, and the coating solution itself did not provide any safety enhancement.

[0089] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for preparing a solid-state electrolyte integrated composite modified cathode material, characterized in that: The specific steps are as follows: Step 1: Prepare the precursor solution for the solid electrolyte; the general molecular formula of the solid electrolyte material is AMO3, AM1M2P3O 12 Li5La3M2O 12 In this mixture, A and M are metallic elements; A is lithium, sodium, potassium, silver, hydrogen, magnesium, calcium, copper, nickel, manganese, cobalt, zinc, or aluminum ions; element M is aluminum, magnesium, sodium, titanium, zirconium, or boron. To prepare the precursor solution, first add the solid raw material from the solid electrolyte raw material to the solvent, stirring at 200-500 rpm at a solution temperature of 25℃-60℃. After stirring until completely dissolved, add the liquid raw material to the mixture, stirring at 400-700 rpm at a solution temperature of 25℃-60℃. Stir until homogeneous. Dry the solution for 30 minutes to 3 hours, then stir again at 500-800 rpm at a solution temperature of 50℃-70℃ for 30-90 minutes to obtain the precursor solution. Step 2: Add the ternary precursor and lithium source to the precursor solution and stir according to a set procedure. Specifically, the stirring speed in the first stage is 200~500 rpm, the solution temperature is 40℃~60℃, and the stirring time is 30min~60min; the stirring speed in the second stage is 400~700 rpm, the solution temperature is 50℃~80℃, and the stirring time is 60min~120min; the stirring speed in the third stage is 500~900 rpm, the solution temperature is 60℃~90℃, and the stirring time is 100min~180min. The resulting suspension is then used to generate pre-sintered material through liquid-phase reaction or spray granulation. Step 3: Sinter the pre-sintered material to obtain a solid electrolyte integrated composite modified cathode material.

2. The preparation method of the solid electrolyte integrated composite modified cathode material according to claim 1, characterized in that: The temperature during the stirring process can be controlled by using an oil bath or a water bath.

3. The preparation method of the solid electrolyte integrated composite modified cathode material according to claim 1, characterized in that: In step two, the chemical formula of the high-nickel ternary cathode material precursor is Ni. x Co y Mn 1-x-y (OH)₂, where 0.6 ≤ x ≤ 1, 0 <y≤0.4; The lithium source is one of lithium carbonate, lithium hydroxide, or lithium oxide.

4. The preparation method of the solid electrolyte integrated composite modified cathode material according to claim 1, characterized in that: The suspension is processed through a stepped modular liquid-phase reaction / spray granulation process, specifically as follows: The stirring speed in the first stage is 300-600 rpm, the solution temperature is 50-65℃, and the stirring time is 60-80 min. The second stage involves a stirring speed of 500-800 rpm, a solution temperature of 60-90℃, and a stirring time of 90-135 min. In the third stage of the process, liquid phase stirring and evaporation are continued at a stirring speed of 500-900 rpm, a solution temperature of 70-110℃, and a stirring time of 120-540 min. In the final stage of the process, continue liquid-phase stirring at a speed of 300-500 rpm and a solution temperature of 70-110℃ until the suspension becomes a mud-like or colloidal pre-sintered material. or, The stirring speed in the first stage is 300-600 rpm, the solution temperature is 50-65℃, and the stirring time is 60-80 min. The second stage involves a stirring speed of 500-800 rpm, a solution temperature of 60-90℃, and a stirring time of 90-135 min. In the third stage of the process, the liquid phase is kept under stirring at a speed of 500 rpm, and the suspension is connected to the spray drying / fluidized bed equipment. The final stage of the process involves spray drying / fluidized bed granulation. The characteristic parameters of this process are: nozzle diameter of 0.1-20 mm, granulation temperature of 80-350 ℃, raw material pump speed of 5-100 ml / min, and hot air pressure in the reaction vessel of 0.15-3 MPa, ultimately yielding pre-sintered material.

5. The preparation method of the solid electrolyte integrated composite modified cathode material according to claim 1, characterized in that: The pre-sintered material is subjected to gradient high-temperature sintering; the sintering process is carried out in sequence as preliminary heat treatment, intermediate heat treatment and final heat treatment; the preliminary heat treatment process is: heat treatment at 250-450℃ for 0-5h, the intermediate heat treatment process is: heat treatment at 500-700℃ for 2-9h, and the final heat treatment process is: heat treatment at 700-1000℃ for 6-18h.

6. The solid electrolyte integrated composite modified cathode material prepared by the preparation method of any one of claims 1-5.

7. The solid electrolyte integrated composite modified cathode material according to claim 6, characterized in that: This includes a composite modified core and a shell encapsulating the core, with the shell being a nano-coating layer formed by the solid electrolyte; the cathode material is doped with element M, and the concentration of dopant element M varies gradient from the interior to the surface of the cathode material particles, eventually becoming enriched on the surface; the chemical formula of the cathode material is LiNi. x Co y Mn z M a O2, 0.6≤x≤1, 0 <y≤0.4,0≤z≤0.4。 8. A battery comprising the solid electrolyte integrated composite modified cathode material as described in claim 7.

9. The battery according to claim 8, characterized in that: The battery is a lithium secondary battery or a lithium solid-state battery.

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