Composite metal oxide coated solid state electrolyte, and method of preparation and use

Abstract

The application discloses a kind of composite metal oxides of coated solid electrolyte and preparation method and application, and the composite metal oxide includes: metal oxide, and the solid electrolyte coating layer of coating in the outer surface of metal oxide;Metal oxide includes: one or more of aluminum oxide Al2O3, magnesium oxide MgO, zinc oxide ZnO or copper oxide CuO;Solid electrolyte coating layer is lithium ion solid electrolyte;Composite metal oxide is obtained by twice calcination reaction from the particle of metal oxide and lithium ion solid electrolyte;Metal oxide and solid electrolyte coating layer have transition layer;Transition layer is formed by the chemical bond effect between metal oxide and lithium ion solid electrolyte;The above-mentioned composite metal oxide is applied to lithium ion battery, and the rate capability and long cycle performance of battery can be improved;The preparation method of a kind of composite metal oxide of coated solid electrolyte provided by the application is simple to operate and easy to realize.

Description

Technical Field

[0001] This invention relates to the field of lithium battery materials technology, and in particular to a composite metal oxide coated with a solid electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are now widely used in all aspects of human life. Although lithium-ion batteries possess excellent characteristics such as high energy density, long cycle life, no memory effect, and cleanliness, they still face many technological obstacles. To improve the cycle stability and thermal safety of lithium-ion batteries, metal oxide materials are used for coating, doping, and slurry addition of positive and negative electrode active materials, which can significantly improve interface stability and increase cycle life. Furthermore, metal oxides are also used in separator coatings to reduce the thermal shrinkage rate of the separator, reducing safety hazards such as short circuits during lithium battery thermal runaway, thereby improving the intrinsic thermal safety of the battery.

[0003] However, commonly used metal oxides, such as Al2O3, MgO, ZnO, and CuO, cannot conduct lithium ions or electrons. When applied in the aforementioned situations, they significantly hinder lithium ion migration, leading to a decrease in battery rate performance. While replacing traditional metal oxide materials with lithium-ion solid-state electrolytes can solve this problem, the cost of lithium-ion solid-state electrolytes is 2-10 times that of traditional metal oxides. Therefore, their application increases production costs, making rapid adoption in the existing lithium battery industry difficult. Furthermore, although smaller particle size lithium-ion solid-state electrolytes offer better dispersion and can reduce the amount added to lithium batteries, their use in separator coatings significantly reduces adhesion to the base film, causing separator coating powdering and hindering practical application. Summary of the Invention

[0004] This invention provides a composite metal oxide coated with a solid electrolyte, its preparation method, and its application. The purpose is to solve the problems that traditional metal oxides cannot conduct lithium ions or electrons, which can lead to significant obstacles to lithium ion migration and a decrease in battery rate performance. It also addresses the issues of high cost and poor adhesion between small-particle-size lithium ion solid electrolytes and separators when used alone.

[0005] In a first aspect, embodiments of the present invention provide a composite metal oxide coated with a solid electrolyte, the composite metal oxide comprising: a metal oxide, and a solid electrolyte coating layer coated on the outer surface of the metal oxide;

[0006] The metal oxide includes one or more of the following: aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO);

[0007] The lithium-ion solid electrolyte in the solid electrolyte coating layer includes: Li 1+x Al x Ti 2-x (PO4)3, Li 1+ y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3-z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, 0 < m < 2;

[0008] The composite metal oxide is obtained by reacting the metal oxide with the particles of the lithium-ion solid electrolyte through two calcination reactions.

[0009] A transition layer exists between the metal oxide and the solid electrolyte coating layer; the transition layer is formed through chemical bonding between the metal oxide and the lithium-ion solid electrolyte.

[0010] Preferably, the particle size D50 of the metal oxide is between 100 nm and 1 μm;

[0011] The thickness of the solid electrolyte coating layer is 50nm-500nm;

[0012] The thickness of the transition layer is 1nm-10nm.

[0013] Secondly, embodiments of the present invention provide a method for preparing the composite metal oxide coated with a solid electrolyte as described in the first aspect above, the method comprising:

[0014] Metal oxide and lithium-ion solid electrolyte particles are placed in a mixing device in a certain proportion and mixed evenly. Then, the mixture is placed in a high-temperature device for the first calcination. After the first calcination is completed and cooled to room temperature, a pre-calcined mixture material is obtained.

[0015] The pre-calcined mixture is pulverized and then placed back into the mixing equipment for uniform mixing to obtain the precursor material;

[0016] The precursor material is placed in a high-temperature device for a second calcination. After the second calcination is completed and the material is cooled to room temperature, a composite metal oxide coated with a solid electrolyte is obtained.

[0017] Preferably, the metal oxide comprises one or more of aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO); the particle size D50 of the metal oxide is between 100 nm and 1 μm.

[0018] The lithium-ion solid electrolyte includes: Li 1+x Al x Ti 2-x (PO4)3, Li 1+y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3- z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, 0 < m < 2; the particle size D50 of the lithium-ion solid electrolyte is between 20 nm and 300 nm;

[0019] The mass ratio of the metal oxide to the lithium-ion solid electrolyte is [70-99]:[30-1].

[0020] Preferably, the particle size D50 of the metal oxide is between 200 nm and 800 nm;

[0021] The particle size D50 of the lithium-ion solid electrolyte is between 50nm and 200nm.

[0022] Preferably, the high-temperature equipment is a muffle furnace;

[0023] The mixing equipment is a high-energy ball mill with a ball milling rate of 500 rpm to 1000 rpm and a mixing time of 0.5 hours to 18 hours.

[0024] Preferably, the temperature of the first calcination is 300℃-600℃, and the time is 0.5 hours-4 hours;

[0025] The second calcination is carried out at a temperature of 600℃-1200℃ for 2-8 hours.

[0026] Preferably, the temperature of the first calcination is 400℃-550℃, and the time is 1 hour-3 hours;

[0027] The second calcination is carried out at a temperature of 750℃-1000℃ for 3 hours to 6.5 hours.

[0028] Thirdly, embodiments of the present invention provide an application of the composite metal oxide coated with a solid electrolyte as described in the first aspect above. The composite metal oxide coated with a solid electrolyte is used to coat and modify the positive or negative active material of a lithium-ion battery, or as an additive in the slurry of the positive or negative active material, or as a coating material on the surface of the separator or current collector of the lithium-ion battery, or as a solid electrolyte of the lithium-ion battery.

[0029] Preferably, the lithium-ion battery includes any one of the following: liquid lithium-ion battery, semi-solid lithium battery, and all-solid lithium battery.

[0030] This invention provides a composite metal oxide coated with a solid electrolyte, its preparation method, and its application. Through a two-stage calcination process, a lithium-ion solid electrolyte is coated onto the outer surface of the metal oxide, forming a transition layer between the metal oxide and the solid electrolyte coating. The metal oxide in the transition layer, after two calcinations, exhibits strong bonding with the solid electrolyte coating, resulting in a composite metal oxide with superior mechanical properties. When applied to lithium-ion batteries, the lithium-ion solid electrolyte layer coated on the outer surface of the composite metal oxide reduces battery polarization and improves rate performance and cycle performance. Furthermore, the metal oxide, as the core, significantly reduces material costs compared to using lithium-ion solid electrolyte alone. Simultaneously, coating the lithium-ion solid electrolyte onto the outer surface of the metal oxide avoids adhesion problems with the separator when using small-particle lithium-ion solid electrolyte, thereby improving the adhesion of the material when used for separator coating.

[0031] The present invention provides a method for preparing a composite metal oxide coated with a solid electrolyte, which has the advantages of wide availability of raw materials, simple production process, easy implementation, low production cost, good repeatability, and mass production capability. Attached Figure Description

[0032] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0033] Figure 1 This is a flowchart of a method for preparing a composite metal oxide coated with a solid electrolyte, provided in an embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0035] This invention provides a composite metal oxide coated with a solid electrolyte, comprising: a metal oxide, and a solid electrolyte coating layer on the outer surface of the metal oxide; the composite metal oxide is obtained by reacting the metal oxide with lithium-ion solid electrolyte particles through two calcination reactions.

[0036] A transition layer exists between the metal oxide and the solid electrolyte coating layer; the transition layer is formed by chemical bonding between the metal oxide and the lithium-ion solid electrolyte; the thickness of the solid electrolyte coating layer is 50nm-500nm; and the thickness of the transition layer is 1nm-10nm.

[0037] The metal oxides include one or more of aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO); the particle size D50 of the metal oxides is between 100 nm and 1 μm.

[0038] The lithium-ion solid electrolyte in the solid electrolyte coating layer includes: Li 1+x Al x Ti 2-x (PO4)3, Li 1+ y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3-z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, and 0 < m < 2.

[0039] This invention provides a method for preparing the above-mentioned composite metal oxide coated with a solid electrolyte, such as... Figure 1 As shown, the specific steps include:

[0040] Step 110: The metal oxide and lithium-ion solid electrolyte particles are placed in a mixing device in proportion, mixed evenly, and then placed in a high-temperature device for the first calcination. After the first calcination is completed and cooled to room temperature, the pre-calcined mixture material is obtained.

[0041] The metal oxides include one or more of aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO); the particle size D50 of the metal oxides is between 100 nm and 1 μm, preferably between 200 nm and 800 nm.

[0042] Lithium-ion solid electrolytes include: Li 1+x Al x Ti 2-x(PO4)3, Li 1+y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3-z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, 0 < m < 2; the particle size D50 of the lithium-ion solid electrolyte is between 20 nm and 300 nm, preferably between 50 nm and 200 nm;

[0043] The mass ratio of metal oxide to lithium-ion solid electrolyte is [70-99]:[30-1];

[0044] The high-temperature equipment is a muffle furnace; the temperature of the first calcination is 300℃-600℃, preferably 400℃-550℃, and the time of the first calcination is 0.5 hours-4 hours, preferably 1 hour-3 hours.

[0045] Step 120: Crush the pre-calcined mixture material and mix it evenly again in the mixing equipment to obtain the precursor material;

[0046] The mixing equipment in this step is a high-energy ball mill with a ball milling rate of 500 rpm to 1000 rpm and a mixing time of 0.5 hours to 18 hours.

[0047] Step 130: The precursor material is placed in a high-temperature device for a second calcination. After the second calcination is completed and cooled to room temperature, the composite metal oxide coated with solid electrolyte is obtained.

[0048] The high-temperature equipment is a muffle furnace; the temperature of the second calcination is 600℃-1200℃, preferably 750℃-1000℃, and the time of the second calcination is 2 hours-8 hours, preferably 3 hours-6.5 hours.

[0049] The composite metal oxide coated with solid electrolyte prepared by the above preparation method provided in the embodiments of the present invention can be used to coat or modify the positive or negative active material of lithium-ion battery, or as an additive in the slurry of positive or negative active material, or as a coating material on the surface of the separator or current collector of lithium-ion battery, or as a solid electrolyte of lithium-ion battery.

[0050] The aforementioned lithium-ion batteries include any one of the following: liquid lithium-ion batteries, semi-solid lithium batteries, and all-solid lithium batteries.

[0051] To better understand the technical solution provided by the present invention, the preparation method of the composite metal oxide coated with solid electrolyte of the present invention is described below with specific examples.

[0052] Example 1

[0053] This embodiment provides a method for preparing a composite metal oxide coated with a solid electrolyte. The specific preparation steps are as follows:

[0054] (1) The metal oxide Al2O3 with a particle size D50 of 700 nm and the lithium-ion solid electrolyte Li2O3 with a particle size D50 of 20 nm were combined. 1.3 Al 0.3 Ti 1.7 (PO4)3 particles were weighed at a mass ratio of 99:1 and placed in a high-energy ball mill at a ball milling rate of 800 rpm. After mixing for 1 hour until homogeneous, the mixture was placed in a muffle furnace and calcined for the first time at 300°C for 4 hours. After the first calcination was completed and cooled to room temperature, the pre-calcined mixture material was obtained.

[0055] (2) The pre-burned mixture is placed in a pulverizer for pulverization, and then placed in a high-energy ball mill at a ball milling rate of 800 rpm for 0.5 hours to mix evenly and obtain the precursor material.

[0056] (3) The precursor material was placed in a muffle furnace and calcined for a second time at 750°C for 3 hours. After the second calcination was completed, the material was cooled to room temperature and discharged to obtain a composite metal oxide coated with solid electrolyte.

[0057] The membrane prepared using the composite metal oxide coated with solid electrolyte in this embodiment was then subjected to a peel strength test. The specific process is as follows:

[0058] The membrane preparation process is as follows: The above-mentioned composite metal oxide, sodium polymethacrylate, styrene-acrylic emulsion, polyoxyethylene methanol ether, and sodium carboxymethyl cellulose were weighed in a mass ratio of 100:0.2:25:10:0.1 and dissolved in deionized water to obtain a slurry with a solid content of approximately 35%. A 3μm thick slurry coating was applied to both sides of a 9μm thick polyethylene (PE) base film using a microgravure coating method. After baking at 60℃ for 2 hours, the film was wound up. The peel strength between the coating and the base film was tested using a peel strength tester; the test results are detailed in Table 1.

[0059] The composite metal oxide coated with solid electrolyte obtained in this embodiment is used as an additive and doped into the slurries of the positive and negative active materials, respectively, to prepare positive and negative electrode sheets and assemble them into a coin cell lithium-ion battery. The specific process is as follows:

[0060] Preparation of coin cell lithium-ion batteries: The positive electrode active material is lithium cobalt oxide, and the negative electrode active material is graphite. 3% of the above-mentioned composite metal oxide is added during the positive electrode homogenization and negative electrode homogenization processes. The positive electrode sheet and negative electrode sheet are prepared by coating aluminum foil and copper foil respectively. Then, they are assembled into coin cell lithium-ion batteries with double-sided alumina separator and electrolyte according to conventional methods. The electrolyte is a 1 mol / L LiPF6 solution of ethylene carbonate EC / dimethyl carbonate DMC (the volume ratio of EC to DMC is 1:1).

[0061] Test method: The coin-type lithium-ion batteries prepared above were tested for long-cycle performance between 2.5V and 4.3V. They were charged to the charging termination voltage at rates of 0.1C, 0.2C, 0.33C, 1C and 3C respectively, and then discharged to the discharge termination voltage at the same rate. Each cycle was repeated 3 times at each rate, and the average charge and discharge capacity at different rates was tested.

[0062] Rate performance is characterized by 1C charging specific capacity / 0.33 charging specific capacity * 100%. The larger the ratio, the better the rate performance. For detailed data on rate performance test calculations and capacity retention test results after 300 cycles, please refer to Table 2.

[0063] Example 2

[0064] This embodiment provides a method for preparing a composite metal oxide coated with a solid electrolyte. The specific preparation steps are as follows:

[0065] (1) MgO, a metal oxide with a particle size D50 of 200 nm, and Li, a lithium-ion solid electrolyte with a particle size D50 of 50 nm, were combined. 1.3 Al 0.3 Ge 1.7 (PO4)3 particles were weighed at a mass ratio of 70:30 and placed in a high-energy ball mill at a ball milling rate of 1000 rpm. After mixing for 0.5 hours until homogeneous, the mixture was placed in a muffle furnace and calcined for the first time at 600℃ for 0.5 hours. After the first calcination was completed and cooled to room temperature, the pre-calcined mixture material was obtained.

[0066] (2) The pre-burned mixture is placed in a pulverizer for pulverization, and then placed in a high-energy ball mill at a ball milling rate of 1000 rpm for 0.5 hours to mix evenly and obtain the precursor material.

[0067] (3) The precursor material was placed in a muffle furnace and calcined for 2 hours at 1000°C. After the second calcination was completed, the material was cooled to room temperature and discharged to obtain a composite metal oxide coated with solid electrolyte.

[0068] The composite metal oxide coated with solid electrolyte prepared in this embodiment was used as an additive and doped into the slurry of positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of rate performance test and the test results of capacity retention rate after 300 cycles are detailed in Table 2.

[0069] Example 3

[0070] This embodiment provides a method for preparing a composite metal oxide coated with a solid electrolyte. The specific preparation steps are as follows:

[0071] (1) A metal oxide ZnO with a particle size D50 of 800 nm and a lithium-ion solid electrolyte Li-ion with a particle size D50 of 200 nm were combined. 0.5 La 0.5 TiO3 particles were weighed at a mass ratio of 85:15 and placed in a high-energy ball mill at a ball milling rate of 800 rpm. After mixing for 2 hours until homogeneous, the mixture was placed in a muffle furnace and calcined for the first time at 400℃ for 3 hours. After the first calcination was completed and cooled to room temperature, the pre-calcined mixture material was obtained.

[0072] (2) The pre-burned mixture is placed in a pulverizer for pulverization, and then placed in a high-energy ball mill at a ball milling rate of 800 rpm for 1 hour to mix evenly and obtain the precursor material.

[0073] (3) The precursor material was placed in a muffle furnace and calcined for 8 hours at 600°C. After the second calcination was completed, the material was cooled to room temperature and discharged to obtain a composite metal oxide coated with solid electrolyte.

[0074] The composite metal oxide coated with solid electrolyte prepared in this embodiment was used as an additive and doped into the slurry of positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of rate performance test and the test results of capacity retention rate after 300 cycles are detailed in Table 2.

[0075] Example 4

[0076] This embodiment provides a method for preparing a composite metal oxide coated with a solid electrolyte. The specific preparation steps are as follows:

[0077] (1) The metal oxide CuO with a particle size D50 of 1 μm and the lithium-ion solid electrolyte Li with a particle size D50 of 300 nm are combined. 6.8 La3Zr 1.8 Ta 0.2 O 12The particles were weighed at a mass ratio of 90:10 and placed in a high-energy ball mill at a ball milling rate of 500 rpm. After mixing for 4 hours until homogeneous, the mixture was placed in a muffle furnace and calcined for the first time at 550°C for 1 hour. After the first calcination was completed and cooled to room temperature, the pre-calcined mixture material was obtained.

[0078] (2) The pre-burned mixture is placed in a pulverizer for pulverization, and then placed in a high-energy ball mill at a ball milling rate of 500 rpm for 2 hours to mix evenly and obtain the precursor material.

[0079] (3) The precursor material was placed in a muffle furnace and calcined for a second time at 1200°C for 4 hours. After the second calcination was completed, the material was cooled to room temperature and discharged to obtain a composite metal oxide coated with solid electrolyte.

[0080] The composite metal oxide coated with solid electrolyte prepared in this embodiment was used as an additive and doped into the slurry of positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of rate performance test and the test results of capacity retention rate after 300 cycles are detailed in Table 2.

[0081] Example 5

[0082] This embodiment provides a method for preparing a composite metal oxide coated with a solid electrolyte. The specific preparation steps are as follows:

[0083] (1) Al2O3, a metal oxide with a particle size D50 of 100 nm, and Li2O3, a lithium-ion solid electrolyte with a particle size D50 of 20 nm, are mixed together. 1.3 Al 0.3 Ti 1.7 (PO4)3 and Li 0.5 La 0.5 TiO3 particles were placed in a high-energy ball mill at a mass ratio of 95:3:2 and the ball milling rate was 800 rpm. After mixing for 2 hours until homogeneous, the mixture was placed in a muffle furnace and calcined for the first time at 450°C for 3.5 hours. After the first calcination was completed and cooled to room temperature, the pre-calcined mixture material was obtained.

[0084] (2) The pre-burned mixture is placed in a pulverizer for pulverization, and then placed in a high-energy ball mill at a ball milling rate of 800 rpm for 1 hour to mix evenly and obtain the precursor material.

[0085] (3) The precursor material was placed in a muffle furnace and calcined for a second time at 900°C for 6.5 hours. After the second calcination was completed, the material was cooled to room temperature and discharged to obtain a composite metal oxide coated with solid electrolyte.

[0086] The composite metal oxide coated with solid electrolyte prepared in this embodiment was used as an additive and doped into the slurry of positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of rate performance test and the test results of capacity retention rate after 300 cycles are detailed in Table 2.

[0087] To better illustrate the effects of the embodiments of the present invention, a comparative example is provided to show the same effects as the embodiments.

[0088] Comparative Example 1

[0089] In this comparative example, the membrane was prepared using the same uncoated metal oxide Al2O3 as in Example 1, and the peel strength was tested. The preparation and testing processes were the same as in Example 1. The peel strength test data are detailed in Table 1.

[0090] In this comparative example, the same uncoated metal oxide Al2O3 as in Example 1 was used as an additive to be doped into the slurries of the positive and negative active materials, respectively, to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of the rate performance test and the test results of the capacity retention rate after 300 cycles are detailed in Table 2.

[0091] Comparative Example 2

[0092] This comparative example uses Li-ion solid electrolytes with the same composition and particle size as those in Example 1. 1.3 Al 0.3 Ti 1.7 (PO4)3.

[0093] This comparative example uses the same lithium-ion solid electrolyte Li in Example 1. 1.3 Al 0.3 Ti 1.7 The membrane was prepared by (PO4)3 and its peel strength was tested. The preparation and testing processes were the same as in Example 1. The peel strength test data are detailed in Table 1.

[0094] This comparative example uses the same lithium-ion solid electrolyte Li in Example 1. 1.3 Al 0.3 Ti 1.7 (PO4)3 was used as an additive to dope the slurries of the positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculation data of rate performance test and the test results of capacity retention rate after 300 cycles are detailed in Table 2.

[0095] Comparative Example 3

[0096] This comparative example uses the same lithium-ion solid electrolyte Li in Example 1. 1.3 Al 0.3 Ti 1.7 (PO4)3 and metal oxide Al2O3 are a binary mixture obtained by ball milling, wherein the mass ratio of the two is exactly the same as that in Example 1.

[0097] In this comparative example, a diaphragm was prepared using the above-mentioned binary mixture and its peel strength was tested. The preparation and testing processes were the same as in Example 1. The peel strength test data are detailed in Table 1.

[0098] In this comparative example, the above-mentioned binary mixture was used as an additive to be doped into the slurries of the positive and negative active materials respectively to prepare positive and negative electrode sheets, which were then assembled into coin-type lithium-ion batteries and tested. The specific process was the same as in Example 1. The calculated data of the rate performance test and the test results of the capacity retention rate after 300 cycles are detailed in Table 2.

[0099] Table 1 summarizes the diaphragm peel strength test data for Example 1 and Comparative Examples 1-3:

[0100] serial number Peel strength (N / m) Example 1 161 Comparative Example 1 125 Comparative Example 2 powder loss Comparative Example 3 89.7

[0101] The peel strength test data in Table 1 shows that the membrane of Comparative Example 2 exhibited powder shedding without requiring a peel strength test. This is because the lithium-ion solid electrolyte used in Comparative Example 2 has a small particle size and a large specific surface area, resulting in poor adhesion to the membrane surface. Therefore, powder shedding occurred before the peel strength test. The peel strength of the membrane in Example 1 is much higher than that in Comparative Examples 1 and 3. This is because the metal oxide coating of the solid electrolyte in Example 1, compared to the uncoated metal oxide in Comparative Example 1 and the binary mixture of solid electrolyte and metal oxide in Comparative Example 3, can further reduce the specific surface area of ​​the coating material and enhance the chemical bonding force between the coating and the base membrane and binder. Therefore, it can improve the adhesion of the metal oxide material to the membrane surface, thereby improving the peel strength of the coating on the membrane surface.

[0102] Table 2 summarizes the test data for preparing coin-type lithium-ion batteries by using the materials from Examples 1-5 and Comparative Examples 1-3 as additives to dope the slurries of positive and negative active materials, respectively, and assembling the positive and negative electrode sheets. The data also includes the rate performance and cycle performance tests of the batteries.

[0103]

[0104]

[0105] As can be seen from the test data in Table 2, compared with Comparative Examples 1-3, the capacity retention rate of the batteries in Examples 1-5 after 300 cycles is significantly improved, and the rate performance is greatly improved. This indicates that after the metal oxides coated with solid electrolytes in Examples 1-5 are added to the positive and negative electrode plates, the kinetic performance of the battery can be improved, the battery polarization can be reduced, and thus the long-cycle performance of the battery can be improved.

[0106] This invention provides a composite metal oxide coated with a solid electrolyte, its preparation method, and its application. Through a two-stage calcination process, a lithium-ion solid electrolyte is coated onto the outer surface of the metal oxide, forming a transition layer between the metal oxide and the solid electrolyte coating. The metal oxide in the transition layer, after two calcinations, exhibits strong bonding with the solid electrolyte coating, resulting in a composite metal oxide with superior mechanical properties. When applied to lithium-ion batteries, the lithium-ion solid electrolyte layer coated on the outer surface of the composite metal oxide reduces battery polarization and improves rate performance and cycle performance. Furthermore, the metal oxide, as the core, significantly reduces material costs compared to using lithium-ion solid electrolyte alone. Simultaneously, coating the lithium-ion solid electrolyte onto the outer surface of the metal oxide avoids adhesion problems with the separator when using small-particle lithium-ion solid electrolyte, thereby improving the adhesion of the material when used for separator coating.

[0107] The present invention provides a method for preparing a composite metal oxide coated with a solid electrolyte, which has the advantages of wide availability of raw materials, simple production process, easy implementation, low production cost, good repeatability, and mass production capability.

[0108] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. 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 composite metal oxide coated with a solid electrolyte, characterized in that, The composite metal oxide includes: a metal oxide, and a solid electrolyte coating layer covering the outer surface of the metal oxide; The metal oxide includes one or more of the following: aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO); The lithium-ion solid electrolyte in the solid electrolyte coating layer includes: Li 1+x Al x Ti 2-x (PO4)3, Li 1+y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3-z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, 0 < m < 2; The composite metal oxide is obtained by reacting the metal oxide with the particles of the lithium-ion solid electrolyte through two calcination reactions. A transition layer exists between the metal oxide and the solid electrolyte coating layer; the transition layer is formed through chemical bonding between the metal oxide and the lithium-ion solid electrolyte.

2. The composite metal oxide coated with a solid electrolyte according to claim 1, characterized in that, The particle size D50 of the metal oxide is between 100 nm and 1 μm; The thickness of the solid electrolyte coating layer is 50nm-500nm; The thickness of the transition layer is 1nm-10nm.

3. A method for preparing a composite metal oxide coated with a solid electrolyte as described in any one of claims 1-2, characterized in that, The preparation method includes: Metal oxide and lithium-ion solid electrolyte particles are placed in a mixing device in a certain proportion and mixed evenly. Then, the mixture is placed in a high-temperature device for the first calcination. After the first calcination is completed and cooled to room temperature, a pre-calcined mixture material is obtained. The pre-calcined mixture is pulverized and then placed back into the mixing equipment for uniform mixing to obtain the precursor material; The precursor material is placed in a high-temperature device for a second calcination. After the second calcination is completed and the material is cooled to room temperature, a composite metal oxide coated with a solid electrolyte is obtained.

4. The preparation method according to claim 3, characterized in that... The metal oxide includes one or more of aluminum oxide (Al2O3), magnesium oxide (MgO), zinc oxide (ZnO), or copper oxide (CuO); the particle size D50 of the metal oxide is between 100 nm and 1 μm. The lithium-ion solid electrolyte includes: Li 1+x Al x Ti 2-x (PO4)3, Li 1+y Al y Ge 2-y (PO4)3, Li 3z La 2 / 3-z TiO3 or Li 7-m La3Zr 2-m Ta m O 12 At least one of the following, wherein 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z < 2 / 3, 0 < m < 2; the particle size D50 of the lithium-ion solid electrolyte is between 20 nm and 300 nm; The mass ratio of the metal oxide to the lithium-ion solid electrolyte is [70-99]:[30-1].

5. The preparation method according to claim 4, characterized in that, The particle size D50 of the metal oxide is between 200 nm and 800 nm; The particle size D50 of the lithium-ion solid electrolyte is between 50nm and 200nm.

6. The preparation method according to claim 3, characterized in that, The high-temperature equipment is a muffle furnace; The mixing equipment is a high-energy ball mill with a ball milling rate of 500 rpm to 1000 rpm and a mixing time of 0.5 hours to 18 hours.

7. The preparation method according to claim 3, characterized in that, The first calcination is carried out at a temperature of 300℃-600℃ for a time of 0.5 hours-4 hours. The second calcination is carried out at a temperature of 600℃-1200℃ for 2-8 hours.

8. The preparation method according to claim 7, characterized in that, The temperature of the first calcination is 400℃-550℃, and the time is 1 hour-3 hours; The second calcination is carried out at a temperature of 750℃-1000℃ for 3 hours to 6.5 hours.

9. The application of a composite metal oxide coated with a solid electrolyte as described in any one of claims 1-2, characterized in that, The composite metal oxide used to coat the solid electrolyte is used to coat or modify the positive or negative active material of the lithium-ion battery, or as an additive in the slurry of the positive or negative active material, or as a coating material on the surface of the separator or current collector of the lithium-ion battery, or as the solid electrolyte of the lithium-ion battery.

10. The lithium-ion battery according to claim 9, characterized in that, The lithium-ion battery includes any one of the following: liquid lithium-ion battery, semi-solid lithium battery, and all-solid lithium battery.

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