Positive electrode active material and preparation method and application thereof
By composite thermally conductive materials and polymers onto the surface of cathode materials, along with dispersants and surfactants, the problems of insufficient thermal conductivity and poor adhesion of the coating layer are solved, achieving high-efficiency thermal conductivity and stability. This method is applicable to a variety of cathode materials and simplifies the preparation process.
Patent Information
- Application Number
- CN202510784487.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-10-17
AI Technical Summary
Existing cathode materials have insufficient thermal conductivity and poor adhesion of the coating layer, which makes the coating easy to fall off. In addition, the preparation process is complicated and cannot be widely applied to different types of cathode active materials.
By combining positive electrode material with thermally conductive material and polymer, and adding dispersant and surfactant, the thermally conductive material and polymer are uniformly coated on the surface of the positive electrode material through ultrasonic treatment and roller coating, which improves adhesion and maintains the integrity of crystal structure.
It significantly improves the thermal conductivity of cathode materials and the stability of the coating layer, reduces thermal resistance, extends service life, is applicable to a variety of cathode active materials, and simplifies the preparation process.
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Figure BDA0005446707610000101
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of batteries, in particular to a positive electrode active material and a preparation method and application thereof. BACKGROUND
[0002] The positive electrode active material is a core component of a secondary battery (such as a lithium ion battery), and directly affects the key performances of the battery, such as energy density, power density, cycle life and safety. Its role is to store and release lithium ions through reversible redox reactions during the charging and discharging process of the battery, thereby realizing the conversion of electric energy.
[0003] Currently, in the field of surface coating of positive electrode materials, the following methods are mainly used to improve the thermal conductivity and material performance: 1. Carbon-based material coating technology uses graphite, graphene or carbon black to coat the surface of the positive electrode material, and improves the performance by improving the electrical conductivity and partial thermal conductivity of the material. This method has limited thermal conductivity of carbon-based materials, and the structure is prone to damage at high temperatures. 2. Inorganic oxide coating technology: Al2O3, TiO2 or MgO inorganic oxides are used to uniformly coat the positive electrode material by sol-gel method or spray drying method, to improve the interface stability of the positive electrode particles and enhance the thermal stability. This method is difficult to significantly improve the overall thermal conductivity of the material due to the low thermal conductivity of inorganic oxides. 3. Thermal filler coating technology: materials with high thermal conductivity, such as boron nitride (BN), aluminum nitride (AlN) or silicon carbide (SiC), are coated on the surface of the positive electrode material to improve the thermal conductivity. This method has poor adhesion between the filler and the positive electrode material, which can easily cause the coating to fall off or be unevenly dispersed.
[0004] The thermal conductivity of the coating layer in the prior art is limited by the thermal conductivity of the coating material itself, which is difficult to meet the heat dissipation requirements of high-performance solid-state batteries. The adhesion of the coating layer is insufficient: the interface bonding force between the thermal conductive material and the positive electrode particles is poor, which causes the coating layer to fall off during the electrochemical cycle process, affecting the long-term stability. The preparation process is complex: some existing technologies rely on high-temperature sintering, sol-gel and other complex processes, which increases the production cost and difficulty. Insufficient applicability: the existing scheme has strong dependence on specific positive electrode materials, and cannot be widely applied to different types of positive electrode active materials (such as NCM, NCA, etc.).
[0005] In view of this, the present application is proposed. SUMMARY
[0006] The purpose of the present application is to overcome the deficiencies in the prior art and provide a positive electrode active material.
[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of a positive electrode active material, comprising the following steps:
[0008] The positive electrode material, the heat-conducting material and the polymer are added into a solvent, and then a dispersant and a surfactant are added, and the mixture is stirred uniformly and treated by ultrasonic, to obtain a slurry;
[0009] The slurry is rolled to form a film, which is solidified, dried, crushed and sieved, to obtain the positive electrode active material.
[0010] As an embodiment of the present application, the positive electrode material comprises at least one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium iron phosphate and lithium manganese iron phosphate;
[0011] The DV50 particle size of the positive electrode material is 5-20 μm.
[0012] As an embodiment of the present application, the heat-conducting material comprises at least one of boron nitride, aluminum nitride and silicon carbide.
[0013] As an embodiment of the present application, the polymer comprises carboxylated polyvinylidene fluoride.
[0014] As an embodiment of the present application, the carboxyl content of the carboxylated polyvinylidene fluoride is 1-1.5%.
[0015] As an embodiment of the present application, the dispersant comprises polyvinylpyrrolidone, and the average molecular weight of the polyvinylpyrrolidone is 8000-10000.
[0016] As an embodiment of the present application, the surfactant comprises at least one of γ-aminopropyl triethoxysilane, isopropyl tri(dioctyl pyrophosphoryloxy) titanate and cetyltrimethylammonium bromide.
[0017] As an embodiment of the present application, the mass ratio of the positive electrode material, the heat-conducting material, the polymer, the dispersant, the surfactant and the solvent is 100:(3-8):(2-5):(0.5-1.5):(0.2-0.8):(50-100).
[0018] As an embodiment of the present application, the power of the ultrasonic treatment is 200-400 W, and the frequency is 30-50 KHz.
[0019] The gap of the coating is 50-100 μm, and the coating speed is 5-10 cm / s.
[0020] The second aspect of the present application provides a positive electrode active material prepared by the preparation method described above.
[0021] The third aspect of the present application provides an application of the positive electrode active material in preparing a secondary battery.
[0022] The application has the advantages that: the positive electrode material is first compounded with the heat-conducting material and the polymer, and then mixed with the dispersant and the interfacial active agent, the heat-conducting material and the polymer are coated on the surface of the positive electrode material, the heat-conducting coefficient is as high as 200-400 W / (m*K), which is much higher than that of the traditional oxide coating, the heat-conducting material and the polymer are uniformly coated on the surface of the polymer through the dispersant and the interfacial active agent, the adhesion between the coating and the positive electrode particles is improved through physical adsorption and chemical bonding, the uniform distribution of the coating material on the surface of the positive electrode material is realized, meanwhile, the rolling coating film forming method is adopted, the crystal structure of the positive electrode material is not damaged, the heat-conducting performance of the positive electrode material and the stability of the coating layer are significantly improved, and the interfacial bonding force is effectively improved. DETAILED DESCRIPTION
[0023] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.
[0024] In the present application, the technical features described in an open way include both the closed technical solutions composed of the listed features and the open technical solutions containing the listed features.
[0025] In the present application, as no special description is provided, the numerical range is regarded as continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all the ranges disclosed in the present application should be understood as including any and all sub-ranges.
[0026] In the present application, the specific dispersion and stirring treatment methods are not particularly limited.
[0027] Unless otherwise specified, the component raw materials or instruments used in the embodiments and the comparative examples of the present application are commercially available raw materials or instruments, and the component raw materials used in each parallel experiment are the same.
[0028] The embodiment of the present application provides a preparation method of a positive electrode active material, which comprises the following steps:
[0029] The positive electrode material, the heat-conducting material and the polymer are added into a solvent, and then the dispersant and the interfacial active agent are added, and the mixture is stirred uniformly and subjected to ultrasonic treatment to obtain a slurry;
[0030] The slurry is roll-coated into a film, solidified, dried, crushed and sieved to obtain the positive electrode active material.
[0031] The positive electrode material is first compounded with the heat-conducting material and the polymer, and then mixed with the dispersant and the interfacial active agent, so that the heat-conducting material and the polymer are coated on the surface of the positive electrode material, the thermal conductivity is as high as 200-400 W / (m·K), which is much higher than that of the traditional oxide coating, the heat-conducting material and the polymer are uniformly coated on the surface of the polymer through the dispersant and the interfacial active agent, the adhesion between the coating and the positive electrode particles is improved through physical adsorption and chemical bonding, and the uniform distribution of the coating material on the surface of the positive electrode material is realized, meanwhile, the roll-coating method can avoid the damage to the crystal structure of the positive electrode material, significantly improve the thermal conductivity of the positive electrode material and the stability of the coating layer, and effectively improve the interfacial bonding strength.
[0032] The positive electrode material prepared by the method can significantly improve the thermal conductivity, effectively reduce the thermal resistance coefficient of the positive electrode material, significantly improve the battery thermal management performance, reduce the risk of thermal runaway caused by heat accumulation, and has excellent stability in the cycle process due to the high adhesion of the coating layer, and is not easy to fall off, thereby effectively improving the service life of the positive electrode material and the capacity of the secondary battery, and the method is simple and efficient, and has a wide application prospect.
[0033] In one of the embodiments, the positive electrode material includes at least one of lithium nickel cobalt manganese oxide, lithium cobaltate, lithium iron phosphate, and lithium manganese iron phosphate.
[0034] The DV50 particle size of the positive electrode material is 5-20 μm.
[0035] In one of the embodiments, the heat-conducting material includes at least one of boron nitride, aluminum nitride, and silicon carbide.
[0036] In one of the embodiments, the polymer includes carboxylated polyvinylidene fluoride.
[0037] In one of the embodiments, the dispersant includes polyvinylpyrrolidone, and the average molecular weight of the polyvinylpyrrolidone is 8000-10000.
[0038] In one of the embodiments, the interfacial active agent includes at least one of gamma-aminopropyl triethoxysilane, isopropyl tri(dioctyl pyrophosphoryloxy) titanate, and hexadecyl trimethyl ammonium bromide, wherein the interfacial active agent can form a hydrogen bond with the hydroxyl group of the positive electrode material, and the group of the interfacial active agent can be hydrolyzed to generate silanol, and form a Si-O-M (M=Ti, Al, etc.) covalent bond with the heat-conducting material, thereby effectively improving the uniformity of the coating and the interfacial bonding strength.
[0039] In one of the embodiments, the mass ratio of the positive electrode material, the heat-conducting material, the polymer, the dispersant, the interfacial active agent, and the solvent is 100:(3-8):(2-5):(0.5-1.5):(0.2-0.8):(50-100).
[0040] In one of the embodiments, the power of the ultrasonic treatment is 200-400 W, and the frequency is 30-50 KHz.
[0041] The coating gap is 50-100 μm, and the coating speed is 5-10 cm / s.
[0042] In one of the embodiments, the curing temperature is 80-120 °C, and the curing time is 2-4 h.
[0043] In one of the embodiments, the drying temperature is 50-80 °C, and the drying time is 4-20 h.
[0044] The present application provides a positive electrode active material prepared by the above method.
[0045] The present application provides an application of the positive electrode active material in preparing a secondary battery.
[0046] The following examples are provided to facilitate understanding of the present application. These examples are not intended to limit the scope of the claims.
[0047] Example 1
[0048] A method for preparing a positive electrode active material, comprising the following steps:
[0049] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) were added into NMP, and polyvinylpyrrolidone and γ-aminopropyltriethoxysilane were further added, followed by stirring at a speed of 600 rpm for 30 min, and ultrasonic treatment at a power of 300 W and a frequency of 40 KHz for 1 h, to obtain a slurry.
[0050] The slurry was transferred to a drum coater, and was roll-coated into a film with a thickness of 1.2 μm (the coating gap was controlled to be 100 μm, and the coating speed was 8 cm / s), and was cured in an oven at 100 °C for 3 h, and was dried at 60 °C for 12 h. After curing and drying, the film was peeled off, was crushed, and was sieved (the particle size was 5-20 μm), to obtain a granular positive electrode active material.
[0051] The DV50 particle size of the NCM811 is 10 μm.
[0052] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0053] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane, and NMP is 100:5:3:1:0.5:100.
[0054] Example 2
[0055] A preparation method of a positive electrode active material, comprising the following steps:
[0056] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) are added into NMP, and then polyvinylpyrrolidone and gamma-aminopropyl triethoxysilane are added, stirring at a speed of 600 rpm for 30 min, and ultrasonic treatment at 300 W and 40 KHz for 1 h to obtain a slurry;
[0057] The slurry is transferred to a drum coater, and is roll-coated into a film with a thickness of 1.2 μm (the coating gap is controlled to be 100 μm, and the coating speed is 8 cm / s), and is cured in an oven at 100 ℃ for 3 h and dried at 60 ℃ for 12 h, and then is peeled off, crushed, and sieved (the particle size is 5-20 μm) to obtain a positive electrode active material.
[0058] The DV50 particle size of the NCM811 is 10 μm.
[0059] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0060] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane, and NMP is 100:3:5:0.5:0.8:100.
[0061] Example 3
[0062] A preparation method of a positive electrode active material, comprising the following steps:
[0063] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) are added into NMP, and then polyvinylpyrrolidone and gamma-aminopropyl triethoxysilane are added, stirring at a speed of 600 rpm for 30 min, and ultrasonic treatment at 300 W and 40 KHz for 1 h to obtain a slurry;
[0064] The slurry was transferred to a drum coater, and drum-coated into a 1.2-μm film (control coating gap 100 μm, coating speed 8 cm / s), cured in a 100℃ oven for 3 h, dried at 60℃ for 12 h, crushed and sieved (particle size 5-20 μm) to obtain the positive electrode active material.
[0065] The DV50 particle size of the NCM811 is 10 μm.
[0066] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0067] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane, and NMP is 100:8:2:1.5:0.2.
[0068] Comparative Example 1
[0069] Comparative Example 1 differs from Example 1 in that Comparative Example 1 is NCM811 (DV50 particle size 10 μm, without coating).
[0070] Comparative Example 2
[0071] Comparative Example 2 differs from Example 1 in that Comparative Example 2 does not add gamma-aminopropyl triethoxysilane, and is otherwise the same.
[0072] A preparation method of a positive electrode active material, comprising the following steps:
[0073] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) were added to NMP, and then polyvinylpyrrolidone was added, stirred at 600 rpm for 30 min, and treated with ultrasonic waves at 300 W and 40 KHz for 1 h to obtain a slurry;
[0074] The slurry was transferred to a drum coater, and drum-coated into a 1.2-μm film (control coating gap 100 μm, coating speed 8 cm / s), cured in a 100℃ oven for 3 h, dried at 60℃ for 12 h, crushed and sieved (particle size 5-20 μm) to obtain the positive electrode active material.
[0075] The DV50 particle size of the NCM811 is 10 μm.
[0076] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0077] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, and NMP is 100:5:3:1:100.
[0078] Comparative Example 3
[0079] Comparative Example 3 differs from Example 1 in that the amount of γ-aminopropyl triethoxysilane added is different, and the others are the same.
[0080] A preparation method of a positive electrode active material, comprising the following steps:
[0081] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) are added to NMP, and then polyvinylpyrrolidone and γ-aminopropyl triethoxysilane are added, stirring at a speed of 600 rpm for 30 min, and ultrasonic treatment at 300 W and 40 KHz for 1 h to obtain a slurry;
[0082] The slurry is transferred to a drum coater, and is coated into a film with a thickness of 1.2 μm (the coating gap is controlled to be 100 μm, and the coating speed is 8 cm / s), and is cured in an oven at 100°C for 3 h, dried at 60°C for 12 h, and crushed and sieved (particle size 5-20 μm) to obtain a positive electrode active material.
[0083] The DV50 particle size of the NCM811 is 10 μm.
[0084] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0085] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, γ-aminopropyl triethoxysilane, and NMP is 100:5:3:1:0.1:100.
[0086] Comparative Example 4
[0087] Comparative Example 4 differs from Example 1 in that the amount of γ-aminopropyl triethoxysilane added is different, and the others are the same.
[0088] A preparation method of a positive electrode active material, comprising the following steps:
[0089] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1O2), boron nitride, and carboxylated polyvinylidene fluoride (Kynar HSV900, Arkema, carboxyl content 1.2 mol%) were added to NMP, followed by the addition of polyvinyl pyrrolidone and γ-aminopropyltriethoxysilane, and the mixture was stirred at 600 rpm for 30 min and ultrasonically treated at 300 W and 40 kHz for 1 h to obtain a slurry;
[0090] The slurry was transferred to a roller coater and rolled into a 1.2 μm film (the coating gap was controlled to be 100 μm and the coating speed was 8 cm / s), cured in an oven at 100°C for 3 h, dried at 60°C for 12 h, crushed and sieved (particle size 5-20 μm) to obtain the positive electrode active material.
[0091] The DV50 particle size of the NCM811 is 10 μm.
[0092] The average molecular weight of the polyvinyl pyrrolidone is 10,000.
[0093] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinyl pyrrolidone, γ-aminopropyltriethoxysilane, and NMP is 100:5:3:1:1.2:100.
[0094] Comparative Example 5
[0095] The difference between Comparative Example 5 and Example 1 is that, in Comparative Example 5, polyvinylidene fluoride is used to replace carboxylated polyvinylidene fluoride, and all other aspects are the same.
[0096] A method for preparing a positive electrode active material comprises the following steps:
[0097] NCM811(LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, and polyvinylidene fluoride were added to NMP, and then polyvinyl pyrrolidone and γ-aminopropyltriethoxysilane were added, stirred at 600 rpm for 30 min, and ultrasonically treated at 300 W and 40 kHz for 1 h to obtain a slurry;
[0098] The slurry was transferred to a roller coater and rolled into a 1.2 μm film (the coating gap was controlled to be 100 μm and the coating speed was 8 cm / s), cured in an oven at 100°C for 3 h, dried at 60°C for 12 h, crushed and sieved (particle size 5-20 μm) to obtain the positive electrode active material.
[0099] The DV50 particle size of the NCM811 is 10 μm.
[0100] The average molecular weight of the polyvinyl pyrrolidone is 10,000.
[0101] The mass ratio of the NCM811, boron nitride, polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane and NMP is 100:5:3:1:0.5:100.
[0102] Comparative Example 6
[0103] Comparative Example 6 is different from Example 1 in that the ratio of each raw material of Comparative Example 6 is different, and the others are the same.
[0104] A preparation method of a positive electrode active material, comprising the following steps:
[0105] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), boron nitride, carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) are added into NMP, and then polyvinylpyrrolidone and gamma-aminopropyl triethoxysilane are added, stirred at a speed of 600 rpm for 30 min, and treated with ultrasonic waves at a power of 300 W and a frequency of 40 KHz for 1 h to obtain a slurry;
[0106] The slurry is transferred to a drum coater, and a film with a thickness of 1.2 μm is obtained by rolling (the coating gap is controlled to be 100 μm, and the coating speed is 8 cm / s), and then the film is cured in an oven at 100°C for 3 h, dried at 60°C for 12 h, crushed and sieved (the particle size is 5-20 μm) to obtain a positive electrode active material.
[0107] The DV50 particle size of the NCM811 is 10 μm.
[0108] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0109] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane and NMP is 100:1:8:0.2:1:100.
[0110] Comparative Example 7
[0111] Comparative Example 7 is different from Example 1 in that the ratio of each raw material of Comparative Example 7 is different, and the others are the same.
[0112] A preparation method of a positive electrode active material, comprising the following steps:
[0113] NCM811 (LiNi 0.8 Co 0.1 Mn 0.1O2), boron nitride, carboxylated polyvinylidene fluoride (Kynar HSV900 Arkema carboxyl content 1.2 mol%) were added into NMP, then polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane were added, stirred at 600 rpm for 30 min, and treated with ultrasonic at 300 W, 40 KHz for 1 h to obtain a slurry;
[0114] The slurry was transferred to a drum coater, and was coated into a 1.2 μm film (the coating gap was controlled to be 100 μm, and the coating speed was 8 cm / s), was cured in a 100℃ oven for 3 h, was dried at 60℃ for 12 h, was crushed and sieved (particle size 5-20 μm) to obtain the positive electrode active material.
[0115] The DV50 particle size of the NCM811 is 10 μm.
[0116] The average molecular weight of the polyvinylpyrrolidone is 10000.
[0117] The mass ratio of the NCM811, boron nitride, carboxylated polyvinylidene fluoride, polyvinylpyrrolidone, gamma-aminopropyl triethoxysilane, NMP is 100:10:1:2:0.1:100.
[0118] Test Example
[0119] The steady-state heat flow method was used to test the thermal conductivity. Standard: ASTM D5470 (steady-state heat flow method)
[0120] Instrument: LFA467 (Bruker instrument)
[0121] Sample preparation: 1 g of the coated positive electrode material was pressed into a disc with a diameter of 12.7 mm and a thickness of 1 mm at 10 MPa; gold layers were sprayed on both sides to reduce the thermal contact resistance. Test conditions: temperature: 25℃. Heat flow direction: perpendicular to the pressing surface. The average value was obtained by repeating 3 times.
[0122] The peeling strength of the coating layer and the positive electrode material was determined by a universal testing machine.
[0123] After 100 electrochemical cycles, the coating shedding rate was detected, and the cycle capacity retention rate was detected. Coating shedding rate detection method: after the cycle, the battery was disassembled, and the positive electrode sheet was soaked in DMC for 48 h to remove the electrolyte and PVDF binder. The active material particles were collected, and SEM observation was performed after gold spraying (Hitachi SU8010, 5kV)
[0124] The exposed area ratio of the surface of 100 particles was statistically analyzed (ImageJ software analysis)
[0125] Shedding rate = (number of exposed particles / total number of particles) x 100%
[0126] Cycling capacity retention test
[0127] Battery assembly:
[0128] Positive electrode: 90% positive active material + 5% SuperP + 5% PVDF (aluminum foil current collector).
[0129] Negative electrode: lithium metal sheet.
[0130] Electrolyte: 1M LiPF6in EC:DMC = 1:1 (containing 2% VC)
[0131] Model: CR2032 button cell.
[0132] Test procedure (Blue Electric CT3001A):
[0133] 0.1C activation for 2 weeks.
[0134] 1C constant current charge-discharge (2.8-4.3V).
[0135] Record the discharge capacity at the 100th cycle.
[0136] Capacity retention rate = (100th week capacity / 3rd week capacity) x 100%.
[0137] Table 1
[0138]
[0139] As can be seen from Table 1, the positive electrode material is first compounded with the heat-conducting material and the polymer in the application, and can be mixed with the dispersant and the interfacial active agent, the heat-conducting material and the polymer are coated on the surface of the positive electrode material, the thermal conductivity is as high as 200-400 W / (m·K), which is much higher than that of the traditional oxide coating, the heat-conducting material and the polymer are uniformly coated on the surface of the polymer through the dispersant and the interfacial active agent, the adhesion of the coating layer and the positive electrode particles is improved through physical adsorption and chemical bonding, the uniform distribution of the coating material on the surface of the positive electrode material is realized, at the same time, the application adopts the roll coating film forming mode, which can avoid the damage to the crystal structure of the positive electrode material, significantly improve the thermal conductivity of the positive electrode material and the stability of the coating layer, and effectively improve the interfacial bonding force.
[0140] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.
Claims
1. A method for preparing a positive electrode active material, characterized in that: The following steps are involved: Adding the positive electrode material, thermal conductive material, and polymer to a solvent, and then adding a dispersant and a surfactant, stirring evenly, and ultrasonically treating to obtain a slurry; The slurry is rolled into a film, solidified, dried, crushed and sieved to obtain the positive electrode active material.
2. The method for preparing a positive electrode active material according to claim 1, wherein: The positive electrode material includes at least one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium iron phosphate, and lithium manganese iron phosphate; The DV50 particle size of the positive electrode material is 5 to 20 μm.
3. The method for preparing a positive electrode active material according to claim 1, wherein: The thermal conductive material includes at least one of boron nitride, aluminum nitride, and silicon carbide.
4. The method for preparing a positive electrode active material according to claim 1, wherein: The polymer includes carboxylated polyvinylidene fluoride.
5. The method for preparing a positive electrode active material according to claim 1, wherein: The dispersant includes polyvinyl pyrrolidone, and the average molecular weight of the polyvinyl pyrrolidone is 8000-10000.
6. The method for preparing a positive electrode active material according to claim 1, wherein: The surfactant includes at least one of gamma-aminopropyltriethoxysilane, isopropyl tris(dioctylpyrophosphate) titanate, and hexadecyltrimethylammonium bromide.
7. The method for preparing a positive electrode active material according to claim 1, wherein: The mass ratio of the positive electrode material, thermal conductive material, polymer, dispersant, surfactant and solvent is 100: (3-8): (2-5): (0.5-1.5): (0.2-0.8): (50-100).
8. The method for preparing a positive electrode active material according to claim 1, wherein: The power of the ultrasonic treatment is 200-400W and the frequency is 30-50KHz; The coating gap is 50-100 μm, and the coating speed is 5-10 cm / s.
9. A positive electrode active material, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the positive electrode active material according to claim 9 in preparing a secondary battery.