Conductive material-coated ternary precursor, preparation method thereof and application

Abstract

The present invention discloses a conductive material-coated ternary precursor, a preparation method thereof, and an application thereof. The method comprises the following steps: after pretreating the conductive material with a surfactant, performing liquid-phase mixing with the ternary precursor, and drying to obtain the conductive material-coated ternary precursor; wherein, the surfactant comprises polyethylene wax. The method of the present invention pretreats the conductive material with a specific type of surfactant, which can not only improve the conductivity of the precursor of the cathode material and thus improve the conductivity of the subsequently prepared cathode material, but also inhibit further phase transformation, reduce the generation of cracks, and improve the cycle performance and specific capacity of the cathode material.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and relates to a conductive material-coated ternary precursor and its preparation method and application. Background Art

[0002] To meet the high energy demand of electric vehicles, nickel-rich layered materials LiNi 1-x-y Mn x Co y O2(x + y ≤ 0.4) (NMC) and LiNi 0.8 Co 0.15 Al 0.05 O2 are considered the most promising cathode candidate materials. They have a capacity of 200 mAh / g and a high voltage of 3.8 V (vsLi + / Li). However, problems such as Li + / Ni 2+ cation mixing, Li residue, poor thermal stability and conductivity limit the cycle and rate performance of the battery.

[0003] So far, scientists have tried to improve the structural stability by using various strategies, including element doping, surface coating and forming a concentration gradient, etc. Element doping can significantly improve the cycle stability of the cathode material, but it also brings the problem of capacity decline. The concentration gradient is a relatively good method, but the preparation process is more troublesome, severely limiting its large-scale production.

[0004] Coating a protective layer on the secondary particles can isolate the active material from the electrolyte and can well improve the cycle performance. CN109192975A discloses a preparation method of a carbon-coated ternary cathode material, including the following steps: adding ternary precursor wet material A and a lithium salt into a carbon source solution, freeze-drying to obtain ternary precursor material B, and sintering ternary precursor material B to obtain a carbon-coated ternary cathode material; ternary precursor wet material A is obtained by mixing and reacting a ternary mixed salt solution, a precipitant solution, a complexing agent solution and an anionic surfactant solution. This material is not only carbon-coated on the surface, but also carbon-coated inside. The carbon-coated ternary material in the carbon matrix can not only greatly improve its high-rate stability and high-voltage cycle stability, but also greatly improve the stability of its structure and the internal electron conductivity. However, the lithium ion transport channels of the prepared ternary cathode material are discontinuous, easy to crack, and have poor cycle stability.

[0005] CN103474628A discloses a preparation method of a carbon-coated ternary cathode material, which includes the following steps: S1. Using nickel salt, cobalt salt and manganese salt as raw materials, preparing a ternary cathode material precursor; S2. Preparing a conductive carbon dispersion system: dispersing conductive carbon in water containing an organic carbon source; S3. Adding the ternary cathode material precursor and a lithium compound into the conductive carbon dispersion system, mixing evenly to obtain a mixture; S4. Drying the mixture under vacuum conditions; S5. Subjecting the dried mixture to high-temperature treatment under sealed conditions or in an atmosphere protected by an inert gas to obtain a carbon-coated ternary cathode material. This method has uniform coating, simple operation, low cost and high efficiency. Among them, the conductive carbon and the ternary cathode material are simultaneously coated in the network-shaped amorphous carbon, and the amorphous carbon acts as a conductive medium or channel for the conductive carbon and the ternary cathode material, greatly improving the rate performance of the ternary cathode material. However, this method cannot achieve uniform coating, affecting the performance of the cathode material.

[0006] In summary, in the prior art, there are problems of non-uniform coating and insignificant performance improvement in coating carbon materials. Therefore, it is necessary to provide a new method for coating a cathode material with a conductive material to better improve the electrochemical performance of the cathode material. Summary of the Invention

[0007] Aiming at the above problems existing in the prior art, the purpose of the present invention is to provide a conductive material-coated ternary precursor, its preparation method and application.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a preparation method of a conductive material-coated ternary precursor, and the method includes the following steps:

[0010] After pretreating the conductive material with a surfactant, performing liquid-phase mixing with the ternary precursor, and drying to obtain a conductive material-coated ternary precursor;

[0011] Among them, the surfactant includes polyethylene wax (LDPE).

[0012] Conductive materials are generally hydrophobic and have poor dispersibility in water. The method of the present invention pre-treats conductive materials by using a specific type of surfactant. Polyethylene wax can modify conductive materials such as carbon materials to increase the oxygen-containing functional groups thereon, thereby improving the hydrophilicity and dispersibility of the conductive materials. At the same time, the functional groups of polyethylene wax are easily attracted to the metal cations of the ternary precursor, improving the coating effect. Therefore, by performing liquid-phase coating with the ternary precursor after pre-treatment, not only can the conductivity of the precursor of the cathode material be improved, thereby improving the conductivity of the subsequently prepared cathode material, but also further phase transformation can be inhibited, the generation of cracks can be reduced, and the cycle performance and specific capacity of the cathode material are improved.

[0013] The present invention provides a method for simply preparing a coated ternary precursor, which simplifies the production process and is suitable for large-scale production.

[0014] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] Preferably, the pre-treatment includes: dispersing the surfactant and the conductive material into a dispersant to obtain a pre-treated conductive material. The conductive material is modified by the dispersant to increase the oxygen-containing functional groups thereon, thereby improving the hydrophilicity and dispersibility of the conductive material.

[0016] In one embodiment, the dispersant is water.

[0017] In one embodiment, the pre-treatment is carried out under stirring conditions, and the stirring rate is 200 r / min - 400 r / min, such as 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, 300 r / min, 325 r / min, 350 r / min, 370 r / min or 400 r / min, etc. The stirring time is 6 h - 15 h, such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h or 15 h, etc., and preferably 10 h - 13 h.

[0018] In one embodiment, the stirring temperature is 40°C - 90°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C or 90°C, etc., and preferably 40°C - 60°C.

[0019] Preferably, in the step of pretreatment, the mass ratio of polyethylene wax to the conductive material is 1:(20 - 35), such as 1:20, 1:22, 1:24, 1:25, 1:27, 1:30, 1:32, 1:33 or 1:35, etc. If the amount of polyethylene wax used is too small, the modification effect will be poor, affecting the dispersion uniformity of the conductive material and unable to effectively improve the coating uniformity of the precursor; if the amount of polyethylene wax used is too large, the post-treatment process will be cumbersome and affect the material properties.

[0020] Preferably, the ternary precursor includes at least one of nickel-cobalt-manganese hydroxide or nickel-cobalt-aluminum hydroxide.

[0021] Preferably, the conductive material includes at least one of carbon black, carbon nanotubes, graphene, graphite, acetylene black, and Ketjen black, and preferably carbon black. Compared with other conductive materials, carbon black has the advantages of high conductivity, low cost, and high specific surface area, etc., can significantly improve the performance of the cathode material, and is more suitable for industrial production.

[0022] Preferably, the particle size D50 of the ternary precursor is 8 μm - 10 μm, such as 8 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.3 μm, 9.6 μm or 10 μm, etc.

[0023] Preferably, the particle size D50 of the conductive material is 20 nm - 60 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm or 60 nm, etc. The smaller the particle size of the conductive material, the larger the specific surface area, and the easier it is to coat the precursor.

[0024] Preferably, the mass ratio of the pretreated conductive material to the ternary precursor is (0.5 - 3):100, such as 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100 or 3:100, etc.

[0025] Preferably, the liquid-phase mixing includes: dispersing the pretreated conductive material and the ternary precursor into a solvent and stirring.

[0026] Preferably, the solvent includes water.

[0027] Preferably, the ratio of the volume of the solvent to the total mass of the pretreated ternary precursor and the conductive material is (0.8 - 1.5) m 3 / (20 - 35) kg, where the volume of the solvent (0.8 - 1.5) m 3 For example, it can be 0.8 m 3 、0.9 m 3 、1.0 m 3 、1.1 m 3or 1.2 m 3 etc.; The total mass of the pretreated ternary precursor and the conductive material (20 - 35) kg can be, for example, 20 kg, 22 kg, 25 kg, 27.5 kg, 30 kg, 32 kg, 34 kg or 35 kg, etc.

[0028] Preferably, the stirring rate is 200 r / min - 400 r / min, such as 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, 300 r / min, 325 r / min, 350 r / min, 370 r / min or 400 r / min, etc.

[0029] Preferably, the stirring time is 6 h - 15 h, such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h or 15 h, etc., and preferably 10 h - 13 h.

[0030] Preferably, the stirring temperature is 40°C - 90°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C or 90°C, etc., and preferably 40°C - 60°C.

[0031] In the present invention, the carbon material can be more uniformly dispersed by the liquid-phase mixing method, so that the coating effect is better.

[0032] In the present invention, the drying method is not limited. For example, it can be drying, and the drying temperature can be 100°C - 150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc.

[0033] Preferably, the ternary precursor is prepared by a co-precipitation method, and the co-precipitation method includes the following steps:

[0034] The ternary mixed salt solution, the alkali solution and the ammonia water solution are added in parallel to the bottom liquid, and a co-precipitation reaction is carried out under stirring conditions to obtain the ternary precursor.

[0035] Preferably, the salts in the ternary mixed salt solution include at least one of sulfates, nitrates or chlorides.

[0036] Preferably, the concentration of the ternary mixed salt solution is 80 g / L - 120 g / L, such as 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 110 g / L or 120 g / L, etc.

[0037] Preferably, the feeding rate of the ternary mixed salt solution is 6 L / h - 10 L / h, such as 6 L / h, 7 L / h, 8 L / h, 9 L / h or 10 L / h, etc.

[0038] Preferably, the mass concentration of the alkali solution is 28%-32%, such as 28%, 29%, 30%, 31% or 32%, etc.

[0039] Preferably, the feeding rate of the alkali solution is 2 L / h - 3 L / h, such as 2 L / h, 2.2 L / h, 2.4 L / h, 2.7 L / h or 3 L / h, etc.

[0040] Preferably, the mass concentration of the ammonia water solution is 10%-20%, such as 10%, 12%, 13%, 14%, 15%, 16%, 18% or 20%, etc.

[0041] Preferably, the feeding rate of the ammonia water solution is 0.6 L / h - 1.0 L / h, such as 0.6 L / h, 0.7 L / h, 0.8 L / h, 0.9 L / h or 1.0 L / h, etc.

[0042] Preferably, the temperature of the bottom liquid is 40°C - 60°C, such as 40°C, 45°C, 50°C, 55°C or 60°C, etc.

[0043] Preferably, the ammonia concentration in the bottom liquid is 4 g / L - 8 g / L, such as 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, etc.

[0044] Preferably, the pH value of the bottom liquid is 11.0 - 12.0, such as 11.0, 11.3, 11.5, 11.7 or 12.0, etc.

[0045] Preferably, the stirring rate is 200 r / min - 400 r / min, such as 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, 300 r / min, 325 r / min, 350 r / min, 370 r / min or 400 r / min, etc.

[0046] Preferably, during the coprecipitation reaction, the pH value of the reaction system is controlled at 11.0 - 12.0, such as 11.0, 11.3, 11.5, 11.7 or 12.0, etc.

[0047] Preferably, during the coprecipitation reaction, the ammonia concentration of the reaction system is 4 g / L - 8 g / L, such as 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, etc.

[0048] Preferably, during the coprecipitation reaction, the temperature of the reaction system is 40°C - 60°C, such as 40°C, 45°C, 50°C, 55°C or 60°C, etc.

[0049] Preferably, during the coprecipitation reaction until the particle size D50 When it reaches 3 μm - 4 μm (such as 3 μm, 3.2 μm, 3.5 μm or 4 μm, etc.), stop feeding, and continue the reaction until the material reacts completely to obtain the ternary precursor.

[0050] As a preferred technical solution of the preparation method of the conductive material-coated ternary precursor of the present invention, the method comprises the following steps:

[0051] A nickel-cobalt-manganese ternary mixed salt solution with a concentration of 80 g / L - 120 g / L, a liquid caustic solution with a mass concentration of 28% - 32%, and an ammonia water solution with a mass concentration of 10% - 20% are simultaneously and co-currently fed into a reaction kettle containing a bottom liquid with a temperature of 40°C - 60°C, an ammonia water concentration of 4 g / L - 8 g / L, and a pH of 11.0 - 12.0 at a feeding rate of 6 L / h - 10 L / h, 2 L / h - 3 L / h, and 0.6 L / h - 1.0 L / h respectively, and a co-precipitation reaction is carried out at a stirring rate of 200 r / min - 400 r / min. During the reaction process, the pH of the reaction system is controlled to be 10.0 - 12.0, the ammonia concentration is 4 g / L - 8 g / L, and the temperature is 40°C - 60°C. Continuously monitor the particle size. Before the particle size reaches the requirement, a high-efficiency thickener will be used during the reaction process to collect all the particulate matter and return it to the reaction kettle to continue the reaction and grow. When the particle size D50 reaches 3 μm - 4 μm, stop feeding, and continue the reaction until the material reacts completely to obtain the ternary precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2. Among them, the nickel-cobalt-manganese ternary mixed salt solution is at least one of a nickel-cobalt-manganese ternary mixed sulfuric acid solution, a nickel-cobalt-manganese ternary mixed hydrochloric acid solution, and a nickel-cobalt-manganese ternary mixed nitric acid solution.

[0052] Take 2 kg of carbon black and 1 kg (polyethylene wax) and add them to 1 m 3 of water, stir evenly, then add 30 kg of Ni 0.8 Co 0.1 Mn 0.1 (OH)2, stir at a rotation speed of 200 r / min - 400 r / min at 40°C for 12 hours, filter, and dry at 150°C to obtain the conductive material-coated ternary precursor.

[0053] In the second aspect, the present invention provides a conductive material-coated ternary precursor, and the conductive material-coated ternary precursor is prepared by the method described in the first aspect.

[0054] In the third aspect, the present invention provides a ternary material, and the ternary material is prepared by doping lithium and sintering the conductive material-coated ternary precursor described in the second aspect.

[0055] Lithium doping and sintering: After mixing the conductive material-coated ternary precursor with a lithium source, sintering is carried out.

[0056] In a fourth aspect, the present invention provides a lithium-ion battery, and the positive electrode of the lithium-ion battery includes the ternary material described in the third aspect.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) By using a specific type of surfactant to pretreat the conductive material in the method of the present invention, polyethylene wax can modify the carbon material to enhance the oxygen-containing functional groups on the carbon material, thereby improving the hydrophilicity and dispersibility of the carbon material. At the same time, the functional groups of polyethylene wax are easily attracted to the metal cations of the ternary precursor, improving the coating effect. Therefore, by performing liquid-phase coating with the conductive material after pretreatment, not only can the conductivity of the positive electrode material precursor be improved, thereby improving the conductivity of the subsequently prepared positive electrode material, but also further phase transformation can be inhibited, the generation of cracks can be reduced, and the cycle performance and specific capacity of the positive electrode material are improved.

[0059] (2) The present invention provides a simple method for preparing a coated ternary precursor, which simplifies the production process and is suitable for large-scale production. Description of the Drawings

[0060] Figure 1 It is a SEM image of the conductive material-coated ternary precursor prepared in Example 1. Detailed Embodiments

[0061] The technical solutions of the present invention will be further described below in conjunction with the drawings and through specific embodiments.

[0062] In the embodiments of the present invention, the concentration of the nickel-cobalt-manganese sulfuric acid solution refers to the total concentration of the three elements of nickel, cobalt, and manganese.

[0063] In the embodiments of the present invention, the particle size D50 of the carbon black is 30 nm. Ni 0.8 Co 0.1 Mn 0.1 (OH)2 has a particle size D50 of 9 μm.

[0064] Example 1

[0065] This example provides a method for preparing a conductive material-coated ternary precursor, including the following steps:

[0066] (1) Preparation of ternary precursor:

[0067] A sulfuric acid solution of nickel cobalt manganese with a concentration of 100 g / L, a NaOH solution with a mass concentration of 30%, and an ammonia water solution with a mass concentration of 15% are simultaneously and cocurrently added to a reaction kettle containing a bottom liquid with a temperature of 50 °C, an ammonia concentration of 6 g / L, and a pH of 11.5 at a feeding rate of 8 L / h, 3 L / h, and 0.6 L / h respectively, and a coprecipitation reaction is carried out at a stirring rate of 300 r / min. During the reaction process, the pH of the reaction system is controlled to be 11.5, the ammonia concentration is 6 g / L, and the temperature is 50 °C. The particle size is continuously monitored. Before the particle size reaches the requirement, a high-efficiency thickener is used in the reaction process to collect all the particulate matter and return it to the reaction kettle for continuous reaction and growth. When the particle size D50 reaches 3.5 μm, the feeding is stopped, and the reaction continues until the material reacts completely to obtain the ternary precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2.

[0068] (2) Coating with conductive material:

[0069] Take 2 kg of carbon black and add it to 1 m 3 of water, then add 0.08 kg of polyethylene wax, stir at 60 °C and 300 r / min for 12 hours to obtain a solution containing modified carbon black;

[0070] Then add 100 kg of Ni 0.8 Co 0.1 Mn 0.1 (OH)2 to the above solution, stir evenly, stir at 60 °C and 300 r / min for 12 hours, filter, and dry at 150 °C to obtain a ternary precursor coated with conductive material.

[0071] Figure 1 is the SEM image of the ternary precursor coated with conductive material.

[0072] This example also provides a ternary material, which is prepared by the following method:

[0073] Mix the above ternary precursor coated with conductive material and LiOH according to a molar ratio of Li / (Ni + Co + Mn) of 1.02:1, and sinter at 800 °C for 16 h in a pure oxygen atmosphere to obtain a ternary cathode material.

[0074] Example 2

[0075] This example provides a preparation method of a ternary precursor coated with conductive material, including the following steps:

[0076] (1) Preparation of ternary precursor:

[0077] A nickel-cobalt-manganese sulfuric acid solution with a concentration of 110 g / L, a NaOH solution with a mass concentration of 32%, and an ammonia water solution with a mass concentration of 20% are simultaneously and co-currently added to a reaction kettle containing a bottom liquid with a temperature of 60 °C, an ammonia concentration of 8 g / L, and a pH of 12 at a feeding rate of 10 L / h, 2 L / h, and 0.6 L / h respectively, and a coprecipitation reaction is carried out at a stirring rate of 400 r / min. During the reaction process, the pH of the reaction system is controlled at 12, the ammonia concentration is 8 g / L, and the temperature is 60 °C. The particle size is continuously monitored. Before the particle size reaches the required value, a high-efficiency thickener is used in the reaction process to collect all the particulate matter and return it to the reaction kettle for continuous reaction and growth. When the particle size D50 reaches 4 μm, the feeding is stopped, and the reaction continues until the material reacts completely to obtain the ternary precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2.

[0078] (2) Coating with conductive material:

[0079] Take 2.5 kg of carbon black and add it to 1.5 m 3 of water, then add 0.09 kg of polyethylene wax, stir at 60 °C and 200 r / min for 14 hours to obtain a solution containing modified carbon black;

[0080] Then add 100 kg of Ni 0.8 Co 0.1 Mn 0.1 (OH)2 to the above solution, stir evenly, stir at 60 °C and 200 r / min for 14 hours, filter, and dry at 120 °C to obtain a ternary precursor coated with conductive material.

[0081] This example also provides a ternary material, which is prepared by the following method:

[0082] Mix the above ternary precursor coated with conductive material and LiOH according to a molar ratio of Li / (Ni + Co + Mn) of 1.05, and sinter at 850 °C for 12 h in a pure oxygen atmosphere to obtain a ternary cathode material.

[0083] Example 3

[0084] The difference from Example 1 is that the amount of polyethylene wax used is 0.5 kg.

[0085] Example 4

[0086] The difference from Example 1 is that the amount of polyethylene wax used is 2 kg.

[0087] Example 5

[0088] The difference from Example 1 is that the amount of carbon black added is 0.1 kg.

[0089] Example 6

[0090] The difference from Example 1 is that the addition amount of carbon black is 5 kg.

[0091] Example 7

[0092] The difference from Example 1 is that carbon black is replaced by carbon nanotubes.

[0093] Comparative Example 1

[0094] The difference from Example 1 is that polyethylene wax is replaced by polyvinyl alcohol.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that polyethylene wax is replaced by polyethylene glycol.

[0097] Comparative Example 3

[0098] The difference from Example 1 is that the pretreatment step with polyethylene wax is not adopted, and carbon black and ternary precursor are directly added to water.

[0099] Comparative Example 4

[0100] The difference from Example 1 is that step (2) is: carbon black, polyethylene wax and Ni 0.8 Co 0.1 Mn 0.1 (OH)2 are directly stirred and mixed evenly, without pretreating carbon black with polyethylene wax alone.

[0101] Detection:

[0102] The positive electrodes are prepared using the ternary cathode materials of Examples 1 - 7 and Comparative Examples 1 - 4, and the method is as follows:

[0103] The cathode material, conductive agent Super P (conductive carbon black), and binder PVDF (polyvinylidene fluoride) are used to prepare a slurry according to a mass ratio of 90:5:5, which is evenly coated on an aluminum foil current collector, taken out after baking in an oven at 80 °C for 12 h, and cut into a positive electrode with a diameter of 12 mm.

[0104] The negative electrode uses a metal lithium foil with a diameter of 18 mm and a thickness of 1 mm.

[0105] The separator uses a Celgard polyethylene porous membrane.

[0106] The electrolyte uses an equal - volume mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with 1 mol / L LiPF6 (lithium hexafluorophosphate) as the electrolyte.

[0107] The positive electrode, negative electrode, separator, and electrolyte were assembled into 2032-type button cells in a glove box with water content and oxygen content below 0.1 ppm. After the cells were placed for 12 h, the initial discharge specific capacity at 0.1C and 1C, as well as the capacity retention rate after 100 cycles at 1C, were measured respectively.

[0108] Table 1

[0109]

[0110] From the comparison between Example 1 and Examples 3 - 4, it can be seen that if the content of polyethylene wax is too small or too large, it will lead to a decline in the modification effect, and further lead to a decline in capacity and cycling performance.

[0111] From the comparison between Example 1 and Examples 5 - 6, it can be seen that if the addition amount of conductive carbon material is too small, the improvement of conductivity is not obvious, and the capacity and cycling performance decline; while if the addition amount of conductive carbon material is too large, the cooperative effect with polyethylene wax will be reduced, and the improvement effect of capacity and cycling performance is not as good as that of Example 1.

[0112] From the comparison between Example 1 and Example 7, it can be seen that both carbon black and carbon nanotubes can well improve the performance of the material, and there are certain differences in the improvement of the material performance between the two.

[0113] From the comparison between Example 1 and Comparative Examples 1 - 4, it can be seen that the selection of the type of polyethylene wax and its addition method both have important effects on the improvement of the dispersion and coating effects.

[0114] The applicant declares that the present invention uses the above examples to illustrate the detailed method of the present invention, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a ternary precursor coated with a conductive material, characterized in that, The method includes the following steps: After the conductive material is pretreated with a surfactant and then mixed with the ternary precursor in a liquid phase, the ternary precursor coated with the conductive material is obtained after drying; Among them, the surfactant includes polyethylene wax; The pretreatment includes: dispersing the surfactant and the conductive material into a dispersant to obtain the pretreated conductive material; in the pretreatment step, the mass ratio of polyethylene wax to the conductive material is 1:(20 - 35); The ternary precursor includes at least one of nickel-cobalt-manganese hydroxide or nickel-cobalt-aluminum hydroxide; The conductive material includes at least one of carbon black, carbon nanotubes, graphene, and graphite.

2. The method according to claim 1, wherein The conductive material is carbon black.

3. The method according to claim 1, wherein The particle size D50 of the ternary precursor is 8μm - 10μm.

4. The method according to claim 1, characterized in that The particle size D50 of the conductive material is 20nm - 60nm.

5. The method according to claim 1, characterized in that, The mass ratio of the pretreated conductive material to the ternary precursor is (0.5 - 3):

100.

6. The method according to claim 1, wherein The liquid-phase mixing includes: dispersing the pretreated conductive material and the ternary precursor into a solvent and stirring.

7. The method according to claim 6, characterized in that The solvent includes water.

8. The method according to claim 6, characterized in that The ratio of the volume of the solvent to the total mass of the pretreated conductive material and the ternary precursor is (0.8 - 1.5) m 3 / (20 - 35) kg.

9. The method according to claim 6, wherein The stirring rate is 200r / min - 400r / min.

10. The method according to claim 6, wherein The stirring time is 6h - 15h.

11. The method according to claim 10, wherein The stirring time is 10h - 13h.

12. The method according to claim 6, wherein The stirring temperature is 40℃ - 90℃.

13. The method according to claim 12, wherein The stirring temperature is 40℃ - 60℃.

14. The method according to claim 1, characterized in that, The ternary precursor is prepared by a co-precipitation method, and the co-precipitation method includes the following steps: Adding a ternary mixed salt solution, an alkali solution, and an ammonia water solution in parallel to a bottom liquid, and performing a co-precipitation reaction under stirring conditions to obtain the ternary precursor.

15. The method according to claim 14, characterized in that, The salts in the ternary mixed salt solution include at least one of sulfates, nitrates, or chlorides.

16. The method according to claim 14, wherein The concentration of the ternary mixed salt solution is 80g / L - 120g / L.

17. The method according to claim 14, characterized in that, The feeding rate of the ternary mixed salt solution is 6L / h - 10L / h.

18. The method according to claim 14, wherein The mass concentration of the alkali solution is 28% - 32%.

19. The method according to claim 14, wherein The feeding rate of the alkali solution is 2L / h - 3L / h.

20. The method according to claim 14, characterized in that, The mass concentration of the ammonia water solution is 10% - 20%.

21. The method according to claim 14, wherein The feeding rate of the ammonia water solution is 0.6L / h - 1.0L / h.

22. The method according to claim 14, wherein The temperature of the bottom liquid is 40℃ - 60℃.

23. The method according to claim 14, characterized in that, The ammonia concentration in the bottom liquid is 4g / L - 8g / L.

24. The method according to claim 14, wherein The pH value of the bottom liquid is 11.0 - 12.

0.

25. The method according to claim 14, wherein The stirring rate is 200r / min - 400r / min.

26. The method according to claim 14, wherein During the co-precipitation reaction, the pH value of the reaction system is controlled at 11.0 - 12.

0.

27. The method according to claim 14, wherein During the co-precipitation reaction, the ammonia concentration of the reaction system is 4g / L - 8g / L.

28. The method according to claim 14, wherein During the co-precipitation reaction, the temperature of the reaction system is 40℃ - 60℃.

29. The method according to claim 14, wherein When the coprecipitation reaction reaches a particle size D 50 of 3 μm - 4 μm, stop feeding and continue the reaction until the reaction of the materials is complete to obtain a ternary precursor.

30. A ternary precursor coated with a conductive material, characterized in that, The conductive material-coated ternary precursor is prepared by the method described in any one of claims 1 - 29.

31. A ternary material, characterized in that, The ternary material is prepared by lithium doping and sintering of the conductive material-coated ternary precursor described in claim 30.

32. A lithium-ion battery, characterized in that, The positive electrode of the lithium-ion battery includes the ternary material described in claim 31.

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