A ternary cathode material, its preparation method and application

Abstract

The present disclosure belongs to the technical field of lithium battery recycling, and specifically relates to a ternary cathode material, a preparation method thereof, and an application. After the lithium nickel cobalt manganese oxide cathode material is placed in a humid environment, Li2O on the surface of the material absorbs water to generate LiOH, and then a substitution reaction occurs with a halogenated alkane to generate lithium halide and alcohol. The preparation method provided by the present disclosure has a shorter process flow, and the prepared ternary cathode material has the advantage of low residual alkali content; since the halogenated alkane has neither strong oxidizing property nor acidity, it will not damage the structure of the ternary material, so that the cathode material maintains excellent electrochemical performance.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of lithium battery recycling. Specifically, it relates to a ternary cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries are widely used in many fields such as 3C electronic products, electric vehicles, and chemical energy storage due to their advantages such as high energy density and long cycle life, and are a research hotspot in the new energy field at present. With the rapid development of new energy vehicles, higher requirements are put forward for the energy density of lithium-ion batteries. As one of the key materials of lithium-ion batteries, the cathode material plays an important role in battery performance.

[0003] The lithium nickel cobalt manganese oxide ternary cathode material has advantages such as high specific capacity, high energy density, low price, and environmental friendliness, and has good application prospects in the field of power batteries. As the nickel content increases, the specific capacity of the ternary cathode material gradually increases, but the cycle stability becomes weaker. Excess lithium salts remain on the surface of the material in the form of oxides during the sintering of high-nickel materials, and the increase in nickel content is likely to cause the mixing of nickel and lithium, and lithium is easily precipitated. Residual lithium is easy to absorb water and carbon dioxide in the air to form LiOH and Li 2 CO 3 layers, which will bring the following two problems: on the one hand, during the slurry mixing and coating processes in battery manufacturing, the slurry is extremely easy to form a jelly-like state, resulting in uneven coating and easy capacity attenuation; on the other hand, the residual alkali is easy to react with the electrolyte at high temperature to generate gas, resulting in battery swelling and bringing serious safety hazards.

[0004] Aiming at the problem of high residual alkali content on the surface of high-nickel ternary materials, currently, the common method is to wash the high-nickel materials with water. However, the washing process is cumbersome, requires a large amount of water resources, and there will be a certain amount of water residue after washing. During the subsequent drying process, the dissolved lithium will be precipitated again, and the residual lithium cannot be removed thoroughly; washing will also damage the structure of the ternary cathode material and reduce the battery performance. For example, CN108878863A discloses a method for improving the surface residual alkalinity of a lithium-ion battery ternary cathode material, in which a nickel cobalt manganese layered cathode material is mixed with water, and the washed powder material is obtained by centrifugal separation; a lithium source is added to anhydrous ethanol and mixed evenly, and then the washed powder material is added and mixed evenly, evaporated completely, dried, and sintered to obtain a lithium-ion battery ternary cathode material. The above method improves the performance of the material by replenishing lithium and secondary sintering the ternary material after washing, but the added lithium is not easy to completely react with the material, and it is easy to cause too much lithium remaining, affecting the electrochemical performance of the material.

[0005] Therefore, the existing methods for removing residual alkali generally have the problem of incomplete removal of residual alkali, and it is also easy to cause damage to the structure of the cathode material and affect the electrochemical performance.

[0006] In view of this, the present disclosure is hereby provided. Summary of the Invention

[0007] An object of the present disclosure is to provide a ternary cathode material, a preparation method thereof, and an application thereof, aiming to more thoroughly remove the residual alkali on the surface of the ternary cathode material while ensuring the electrochemical performance of the ternary cathode material.

[0008] To achieve the above object of the present disclosure, the following technical solutions may be adopted:

[0009] In a first aspect, the solution provided by the present disclosure includes a preparation method of a ternary cathode material, including: subjecting a lithium nickel cobalt manganese oxide cathode material to a water absorption treatment and then reacting it with a halogenated alkane.

[0010] In some embodiments of the present disclosure, the halogenated alkane is selected from at least one of monohalides, dihalides, trihalides, and tetrahalides, and the halogen element in the halogenated alkane is selected from at least one of fluorine, chlorine, and bromine.

[0011] In some embodiments of the present disclosure, the halogenated alkane is a monohalide.

[0012] In some embodiments of the present disclosure, the halogenated alkane is selected from at least one of methyl fluoride, ethyl fluoride, methyl chloride, ethyl chloride, methyl bromide, and ethyl bromide.

[0013] In some embodiments of the present disclosure, the process of the water absorption treatment includes: placing the lithium nickel cobalt manganese oxide cathode material in a humid environment with a humidity of greater than or equal to 50% for placement.

[0014] In some embodiments of the present disclosure, the humidity of the humid environment is 60% - 80%.

[0015] In some embodiments of the present disclosure, the placement time of the lithium nickel cobalt manganese oxide cathode material in the humid environment is 5h - 8h.

[0016] In some embodiments of the present disclosure, during the reaction with the halogenated alkane, the reaction temperature is controlled to be 30°C - 50°C, and the reaction time is 2h - 8h.

[0017] In some embodiments of the present disclosure, during the reaction with the halogenated alkane, the reaction temperature is controlled to be 35°C - 45°C, and the reaction time is 2h - 5h.

[0018] In some embodiments of the present disclosure, when the dosage of the lithium nickel cobalt manganese oxide cathode material is 1.0 kg, the flow rate of the introduced halogenated alkane gas is 0.05 L / min - 0.15 L / min.

[0019] In some embodiments of the present disclosure, the lithium nickel cobalt manganese oxide cathode material is placed in a tube furnace, water vapor is introduced into the tube furnace to make the humidity in the tube furnace meet the requirements, and after standing for 4 h - 10 h, the introduction of water vapor is stopped, and after heating to the reaction temperature, a halogenated alkane gas is introduced for reaction.

[0020] In some embodiments of the present disclosure, before introducing water vapor into the tube furnace, an inert gas is first introduced to exhaust the air in the tube furnace.

[0021] In some embodiments of the present disclosure, the water vapor enters the tube furnace in a spraying manner.

[0022] In some embodiments of the present disclosure, when the halogenated alkane used contains chlorine or bromine, the preparation method further includes: after the reaction with the halogenated alkane is completed, the obtained product is purged.

[0023] In some embodiments of the present disclosure, the chemical formula of the lithium nickel cobalt manganese oxide cathode material is LiNi x Co y Mn z O 2 , where 0.7 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.15, 0.05 ≤ z ≤ 0.15, and x + y + z = 1.

[0024] In some embodiments of the present disclosure, the lithium nickel cobalt manganese oxide cathode material is in powder form, and the average particle size of the powder is 2 μm - 15 μm.

[0025] In some embodiments of the present disclosure, the preparation method of the lithium nickel cobalt manganese oxide cathode material includes: mixing a nickel cobalt manganese ternary precursor with a lithium source, performing a first calcination in an oxygen-containing atmosphere to obtain a first calcined product, and then performing a second calcination on the first calcined product in an oxygen-containing atmosphere.

[0026] In some embodiments of the present disclosure, the calcination temperature of the first calcination is 500 °C - 600 °C, and the calcination time is 4 h - 7 h.

[0027] In some embodiments of the present disclosure, the calcination temperature of the second calcination is 700 °C - 800 °C, and the calcination time is 10 h - 18 h.

[0028] In some embodiments of the present disclosure, by controlling the amounts of the nickel cobalt manganese ternary precursor and the lithium source, the molar ratio of the total amount of nickel, cobalt, and manganese to the lithium element is 1: (1.01 - 1.20).

[0029] In some embodiments of the present disclosure, the lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

[0030] In some embodiments of the present disclosure, before the primary calcined product is subjected to secondary calcination, the primary calcined product is cooled and then pulverized to 2 μm - 15 μm.

[0031] In a second aspect, the solution provided by the present disclosure further includes a ternary cathode material, which is prepared by the preparation method in any of the above embodiments.

[0032] In a third aspect, the solution provided by the present disclosure further includes a positive electrode sheet for a lithium-ion battery, which includes a positive electrode current collector and an active coating adhered to the positive electrode current collector, and the active coating contains the ternary cathode material in the above embodiments.

[0033] In a fourth aspect, the solution provided by the present disclosure further includes a lithium-ion battery, which includes the positive electrode sheet for a lithium-ion battery in the above embodiments.

[0034] In a fifth aspect, the solution provided by the present disclosure further includes an electrical device, which includes the lithium-ion battery in the above embodiments.

[0035] After the lithium nickel cobalt manganese oxide cathode material is placed in a humid environment, Li 2 O on the material surface absorbs water to generate LiOH, and then undergoes a substitution reaction with a haloalkane to generate lithium halide and alcohol. Depending on the reaction raw materials, the lithium halide generated may be lithium fluoride, lithium chloride, or lithium bromide. The poorly soluble lithium fluoride can act as a coating layer to protect the cathode material; lithium chloride or lithium bromide is soluble in the generated alcohol and is convenient for subsequent removal. The preparation method provided by the present disclosure has a shorter process flow, and the prepared ternary cathode material has the advantage of low residual alkali content; since the haloalkane has neither strong oxidizing property nor acidity, it will not damage the structure of the ternary material, and the cathode material maintains excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present disclosure, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0037] Figure 1 It is the basic process flow chart adopted by the preparation method provided by the present disclosure;

[0038] Figure 2 It is the process flow chart corresponding to the main process steps in the preparation method provided by the present disclosure;

[0039] Figure 3SEM images of the material before and after being processed using the method of the present disclosure; in the figure, (a) represents before processing, and (b) represents after processing. Detailed implementation manners

[0040] The following will describe the implementation schemes of the present disclosure in detail with reference to embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. For those not specified in the embodiments, they are carried out under conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0041] In the ranges disclosed in the present disclosure, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0042] The solution provided by the embodiment of the present disclosure includes a preparation method of a ternary cathode material, as Figure 1 shown. The preparation process includes: absorbing water by the lithium nickel cobalt manganese oxide cathode material in a humid environment to obtain a cathode material with LiOH on the surface, and then reacting with a haloalkane to remove the residual alkali on the surface through a substitution reaction.

[0043] Specifically, as Figure 2 shown, the preparation method of the ternary cathode material provided by the embodiment of the present disclosure may include the following steps:

[0044] S1. Prepare the lithium nickel cobalt manganese oxide cathode material

[0045] The chemical formula of the lithium nickel cobalt manganese oxide cathode material is LiNi x Co y Mn z O 2 , where 0.7 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.15, 0.05 ≤ z ≤ 0.15, and x + y + z = 1, belonging to a high-nickel cathode material. Specifically, the value of x can be 0.70, 0.75, 0.80, 0.85, 0.90, etc., the value of y can be 0.05, 0.08, 0.10, 0.12, 0.15, etc., and the value of z can be 0.05, 0.08, 0.10, 0.12, 0.15, etc.

[0046] The lithium nickel cobalt manganese oxide cathode material is preferably in powder form to enable subsequent water absorption and substitution reactions to proceed quickly and fully. The average particle size of the powder can be 2μm - 15μm, such as 2μm, 5μm, 8μm, 10μm, 12μm, 15μm, etc.

[0047] It should be noted that the lithium nickel cobalt manganese oxide cathode material can be a commercially available product or can be synthesized independently.

[0048] In some embodiments, the preparation method of the lithium nickel cobalt manganese oxide cathode material includes: mixing a nickel cobalt manganese ternary precursor with a lithium source, performing a first calcination in an oxygen-containing atmosphere to obtain a first calcined product, and then performing a second calcination on the first calcined product in an oxygen-containing atmosphere to prepare a lithium nickel cobalt manganese oxide cathode material with excellent electrochemical performance through a two-step calcination process.

[0049] In some embodiments, the calcination temperature of the first calcination is 500°C - 600°C, and the calcination time is 4h - 7h; the calcination temperature of the second calcination is 700°C - 800°C, and the calcination time is 10h - 18h. By controlling the calcination temperature and time of the two-step calcination, the electrochemical performance of the prepared lithium nickel cobalt manganese oxide cathode material is further ensured.

[0050] Specifically, the calcination temperature of the first calcination can be 500°C, 520°C, 550°C, 580°C, 600°C, etc., and the calcination time can be 4h, 5h, 6h, 7h, etc.; the calcination temperature of the second calcination can be 700°C, 720°C, 750°C, 780°C, 800°C, etc., and the calcination time can be 10h, 12h, 15h, 18h, etc. The oxygen-containing atmosphere used in the two-step calcination process can be but is not limited to oxygen.

[0051] In some embodiments, by controlling the amounts of the nickel cobalt manganese ternary precursor and the lithium source, the molar ratio of the total amount of nickel, cobalt, and manganese to the lithium element is 1:(1.01 - 1.20), that is, the lithium source is used in a slightly excessive manner to enable the reaction to proceed fully. Specifically, the molar ratio of the total amount of nickel, cobalt, and manganese to the lithium element can be 1:1.01, 1:1.05, 1:1.10, 1:1.15, 1:1.20, etc.

[0052] Furthermore, the lithium source is selected from at least one of lithium hydroxide and lithium carbonate, and can be any one or both of the above. In other embodiments, other common lithium sources can also be used.

[0053] In some embodiments, the nickel cobalt manganese ternary precursor and the lithium source are mixed and ground until uniformly mixed, and then the first calcination is performed to enable the reaction to proceed fully and improve the uniformity of the product. Similarly, before the second calcination of the first calcined product, the first calcined product is cooled and then pulverized to 2μm - 15μm, such as 2μm, 5μm, 10μm, 15μm, etc.

[0054] S2. Water absorption treatment

[0055] The water absorption treatment can be to place the lithium nickel cobalt manganese oxide cathode material in a humid environment with a humidity greater than or equal to 50% so that Li on the material surface 2 O absorbs water to generate LiOH.

[0056] During the actual operation process, the lithium nickel cobalt manganese oxide cathode material is placed in a tube furnace, water vapor is introduced into the tube furnace to make the humidity in the tube furnace meet the requirements, and after placing for 4h - 10h, the introduction of water vapor is stopped. The placement time depends on the environmental humidity. The greater the environmental humidity, the shorter the placement time, so that Li on the surface 2 O is more fully converted.

[0057] Specifically, the placement time in the tube furnace can be 1h, 3h, 5h, 8h, 10h, etc., preferably 5h - 8h. The water vapor can be introduced by means of a pipeline or sprayed by means of a nozzle. The water vapor can be formed in a manner similar to a humidifier, but is not limited thereto.

[0058] Specifically, the humidity of the humid environment can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc., preferably 60% - 80% to promote the reaction to proceed rapidly. The test method for humidity is a conventional test method, and it can be tested using a temperature and humidity meter.

[0059] In some embodiments, before introducing water vapor into the tube furnace, an inert gas is first introduced to exhaust the air in the tube furnace to avoid the interference of oxygen. The inert gas can be nitrogen, argon, etc., but is not limited thereto.

[0060] S3. React with haloalkanes

[0061] React the cathode material treated in step S2 with a haloalkane. A substitution reaction occurs between the haloalkane gas and the residual alkali (LiOH) on the surface of the cathode material to generate lithium halide and alcohol, which can effectively reduce the amount of residual alkali on the material surface, lower the pH value of the material surface, and reduce the requirement of the material storage for environmental humidity.

[0062] It should be added that the haloalkane has neither strong oxidizing property nor acidity and will not damage the structure of the ternary material, ensuring the electrochemical performance of the material.

[0063] Further, the haloalkane is selected from at least one of monohalides, dihalides, trihalides and tetrahalides, and can be any one of the above; the halogen element in the haloalkane is selected from at least one of fluorine, chlorine and bromine, and can be any one of the above halogen elements or several. Preferably, the haloalkane is a monohalide; more preferably, the haloalkane is selected from at least one of methyl fluoride, ethyl fluoride, methyl chloride, ethyl chloride, methyl bromide and ethyl bromide; further preferably, the haloalkane is selected from at least one of ethyl chloride, ethyl fluoride and ethyl bromide, and the type of haloalkane is optimized to further improve the removal effect of residual alkali. Lithium chloride and lithium bromide generated by the reaction of the haloalkane with the residual alkali are soluble in alcohol, and the removal process is simple. There are no other by-products remaining on the surface of the cathode material, maintaining the electrochemical performance; the insoluble lithium fluoride generated by the reaction can act as a coating layer to protect the cathode material.

[0064] In some embodiments, during the reaction with the haloalkane, the reaction temperature is controlled to be 30°C - 50°C, and the reaction time is 2h - 8h; preferably, the reaction temperature is controlled to be 35°C - 45°C, and the reaction time is 2h - 5h. By regulating the reaction temperature and time, the reaction proceeds more fully.

[0065] Specifically, the reaction temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, etc., and the reaction time can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0066] In the actual operation process, after the reaction in step S2 is completed, the water vapor is stopped from being introduced, and after the temperature is raised to the reaction temperature, the haloalkane gas is introduced for reaction. When the amount of the lithium nickel cobalt manganese oxide cathode material is 0.8 kg - 1.2 kg, the flow rate of the introduced haloalkane gas is 0.05 L / min - 0.15 L / min. By further controlling the amount of the lithium nickel cobalt manganese oxide cathode material and the amount of the introduced haloalkane, the reaction is made more sufficient to achieve the purpose of significantly reducing the residual alkali.

[0067] Specifically, the amount of the lithium nickel cobalt manganese oxide cathode material can be 0.8 kg, 0.9 kg, 1.0 kg, 1.1 kg, 1.2 kg, etc., and the corresponding flow rate of the introduced haloalkane gas can be 0.05 L / min, 0.10 L / min, 0.15 L / min, etc.

[0068] In some embodiments, when the used haloalkane contains chlorine or bromine, the preparation method further includes: purging after the reaction with the haloalkane is completed to remove the alcohol solution on the surface.

[0069] The embodiments of the present disclosure also provide a ternary cathode material prepared by the preparation method in the above embodiments, which has the advantages of low residual alkali content and excellent electrochemical performance.

[0070] An embodiment of the present disclosure also provides a positive electrode sheet for a lithium-ion battery, which includes a positive electrode current collector and an active coating attached to the positive electrode current collector. The active coating contains the ternary positive electrode material in the above-mentioned embodiment.

[0071] It should be noted that the specific preparation method of the positive electrode sheet for a lithium-ion battery can refer to the prior art. The main steps include: mixing the ternary positive electrode material, binder, and conductive agent to form a slurry, coating it on the positive electrode current collector, and drying to form a coating. The specific types of the binder, conductive agent, and positive electrode current collector are not limited.

[0072] An embodiment of the present disclosure also provides a lithium-ion battery, which includes the positive electrode sheet for a lithium-ion battery in the above-mentioned embodiment, and may also include a negative electrode sheet, electrolyte, separator, etc., and the specific types are not limited. An electrical device can also be prepared using this lithium-ion battery. Due to the improvement of the positive electrode material, the battery has excellent electrochemical performance.

[0073] The features and properties of the present disclosure will be further described in detail below with reference to the embodiments.

[0074] Example 1

[0075] This example provides a preparation method of a ternary positive electrode material, which includes the following steps:

[0076] (1) Mix the high-nickel ternary precursor NCM (molar ratio of nickel, cobalt, and manganese is 0.8:0.1:0.1) and lithium hydroxide at a molar ratio of 1:1.05, grind until evenly mixed, and perform a first calcination in an oxygen atmosphere (purity is 96%, the same below) at a temperature of 550 °C for 5 h. After calcination, cool and crush to 5 μm to obtain a first calcined sample powder; then place the first calcined sample powder in an oxygen atmosphere for a second calcination at a temperature of 750 °C for 15 h to obtain a high-nickel ternary positive electrode material powder.

[0077] (2) Place 1 kg of high-nickel ternary positive electrode material powder with an average particle size of 5 μm in a tube furnace, introduce an inert gas (nitrogen, the same below) to completely exhaust the air in the tube. The chemical formula of the high-nickel ternary material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 .

[0078] (3) Spray water vapor into the tube furnace to keep the humidity in the tube furnace at 65%. The high-nickel ternary positive electrode material powder is placed in a humid environment at room temperature (about 25 °C, the same below) for 10 h.

[0079] (4) Stop introducing water vapor, heat the tubular furnace to 30 °C, then introduce chloroethane gas at a flow rate of 0.05 L / min for 5 h. After purging and removing the generated lithium chloride and ethanol, a cathode material with low residual alkali is obtained.

[0080] Example 2

[0081] This example provides a method for preparing a ternary cathode material, which includes the following steps:

[0082] (1) Mix the high-nickel ternary precursor NCM (nickel-cobalt-manganese molar ratio of 0.8:0.1:0.1) and lithium hydroxide at a molar ratio of 1:1.1, grind until evenly mixed, and perform a first calcination in an oxygen atmosphere at a temperature of 500 °C for 7 h. After calcination, cool and crush to 10 μm to obtain a first calcined sample powder; then place the first calcined sample powder in an oxygen atmosphere for a second calcination at a temperature of 800 °C for 12 h to obtain a high-nickel ternary cathode material powder.

[0083] (2) Place 1 kg of high-nickel ternary cathode material powder with an average particle size of 10 μm in a tubular furnace, introduce an inert gas to completely exhaust the air in the tube. The chemical formula of the high-nickel ternary material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 .

[0084] (3) Spray water vapor into the tubular furnace to keep the humidity at 50%. The high-nickel ternary cathode material powder is placed in a room-temperature and humid environment for 5 h.

[0085] (4) Stop introducing water vapor, heat the tubular furnace to 40 °C, then introduce fluoroethane gas at a flow rate of 0.15 L / min for 2 h to obtain a low-residual-alkali cathode material with a lithium fluoride coating layer.

[0086] Example 3

[0087] This example provides a method for preparing a ternary cathode material, which includes the following steps:

[0088] (1) Mix the high-nickel ternary precursor NCM and lithium hydroxide at a molar ratio of 1:1.2, grind until evenly mixed, and perform a first calcination in an oxygen atmosphere at a temperature of 600 °C for 4 h. After calcination, cool and crush to 8 μm to obtain a first calcined sample powder; then place the first calcined sample powder in an oxygen atmosphere for a second calcination at a temperature of 700 °C for 16 h to obtain a high-nickel ternary cathode material powder.

[0089] (2) Place 1 kg of high-nickel ternary cathode material powder with an average particle size of 8 μm in a tubular furnace, and introduce an inert gas to completely exhaust the air in the tube. The chemical formula of the high-nickel ternary material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 .

[0090] (3) Spray water vapor into the tubular furnace to keep the humidity at 80%. The high-nickel ternary cathode material powder is placed in a room-temperature and humid environment for 2 h.

[0091] (4) Stop introducing water vapor, heat the tubular furnace to 50 °C, then introduce ethyl bromide gas at a flow rate of 0.1 L / min for 4 h. After purging and removing the generated lithium bromide and ethanol, a cathode material with low residual alkali is obtained.

[0092] Example 4

[0093] The difference from Example 1 is only that: ethyl chloride is introduced at a flow rate of 0.05 L / min for 0.5 h.

[0094] Example 5

[0095] The difference from Example 1 is only that: ethyl chloride is introduced at a flow rate of 0.05 L / min for 1 h.

[0096] Example 6

[0097] The difference from Example 1 is only that: ethyl chloride is introduced at a flow rate of 0.05 L / min for 7 h.

[0098] Example 7

[0099] The difference from Example 1 is only that: ethyl chloride is introduced at a flow rate of 0.05 L / min for 9 h.

[0100] Example 8

[0101] The difference from Example 1 is only that: ethyl chloride is replaced with an equal amount of methyl chloride.

[0102] Example 9

[0103] The difference from Example 1 is only that: ethyl chloride is replaced with an equal amount of methyl fluoride.

[0104] Example 10

[0105] The difference from Example 1 is only that: ethyl chloride is replaced with an equal amount of methyl bromide.

[0106] Comparative Example 1

[0107] This comparative example provides a method for removing residual alkali by traditional water washing, and the specific steps are as follows:

[0108] (1) Disperse 1 kg of high-nickel ternary cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 powder into 2 kg of clear water, stir and wash for 10 min, the stirring speed is 1000 r / min, and the washing temperature is 35 °C.

[0109] (2) After the washing is completed, filter and separate the ternary material from the water, and vacuum dry at 100 °C for 4 h to obtain the water-washed ternary material.

[0110] Comparative Example 2

[0111] This comparative example provides a method for removing residual alkali by traditional introduction of strong oxidant, and the specific steps are as follows:

[0112] (1) Place 1 kg of high-nickel ternary cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 powder in a tube furnace, introduce ClO 2 gas, and make the dosage of ClO 2 gas be 10% of the mass of the high-nickel ternary cathode material, the introduction rate is 0.15 L / min, and the reaction time is 4 h.

[0113] (2) After the reaction in step (1) is completed, place the treated cathode material in a vacuum drying oven and vacuum dry at 100 °C for 2 h.

[0114] Comparative Example 3

[0115] This comparative example provides a method for removing residual alkali by pickling treatment with traditional ethanol solution, and the specific steps are as follows:

[0116] (1) Add acetic acid to 100 g of ethanol in an amount such that the molar ratio of residual lithium on the surface of the high-nickel ternary cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 is 1.0, and stir to completely dissolve it to form an ethanol solution of acetic acid;

[0117] (2) Add 100 g of LiNi 0.8 Co 0.1 Mn 0.1 O 2The powder was continuously stirred for 10 min, the solvent was removed by centrifugation, and then dried under vacuum at 70 °C to obtain the treated high-nickel ternary cathode material.

[0118] Test Example 1

[0119] The residual lithium and electrochemical properties of the high-nickel ternary cathode materials obtained in the examples and comparative examples were detected, and the results are shown in Table 1.

[0120] Test method: The prepared high-nickel ternary cathode material was made into a positive electrode sheet. The high-nickel ternary material, binder PVDF, and conductive agent SP were mixed at a mass ratio of 8:1:1, dispersed in the solvent NMP, stirred to form a slurry, the slurry was coated on aluminum foil, dried, and made into a positive electrode sheet. A coin cell was assembled with a lithium metal sheet as the negative electrode for charge-discharge and cycle tests. The test conditions were: all cells were charged and discharged at a rate of 0.1C within a voltage range of 2.8 - 4.3V.

[0121] Table 1 Performance test table of examples and comparative examples

[0122]

[0123] Examples 1 - 3 can effectively reduce the residual alkali content on the surface of the high-nickel ternary cathode material. In Examples 4 - 5, the amount of alkane gas introduced was too small, and the effect of removing residual alkali was not as good as that of the examples. In Examples 6 - 7, too much gas was introduced, which would deposit on the surface of the cathode material particles, affecting the discharge specific capacity. Compared with Example 1, Examples 8 - 10 introduced the same amount of alkane gas of the same nature, and had a similar effect on residual alkali.

[0124] Comparative Example 1 adopted the traditional water washing method to reduce alkali. Although the surface residual alkali of the material was significantly reduced, due to the sensitivity of high nickel to water and the residue of washing water in the internal voids of the material, the cycle performance of the material decreased significantly. Comparative Example 2 was treated with an excessive amount of strong oxidant ClO 2 , resulting in excessive consumption of surface lithium, and a decrease in the initial capacity and capacity retention rate of the battery. Comparative Example 3 adopted pickling treatment with an ethanol solution system, which could remove residual alkali, but the active hydrogen of alcohols would undergo ion exchange with structure L i+ , bringing certain side reactions and leading to a decrease in cycle performance.

[0125] Test Example 2

[0126] The SEM images of the high-nickel ternary cathode materials prepared in the examples and comparative examples were tested, and the results are as Figure 3 shown.

[0127] It can be seen that: The samples before and after the treatment in Example 1 both had a round and uniform particle morphology, indicating that after the treatment, the material structure remained intact and was not damaged.

[0128] The preferred embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited thereto. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present disclosure and fall within the protection scope of the present disclosure.

[0129] Industrial applicability

[0130] After the lithium nickel cobalt manganese oxide cathode material of the present disclosure is placed in a humid environment and then undergoes a substitution reaction with a halogenated alkane, the prepared ternary cathode material has the advantage of low residual alkali content; since the halogenated alkane has neither strong oxidizing property nor acidity, it will not damage the structure of the ternary material, enabling the cathode material to maintain excellent electrochemical performance. The above preparation method has a shorter process flow, and the raw materials used are easily available, which is convenient for industrial application.

Claims

1. A preparation method of a ternary cathode material, characterized in that, it includes: After subjecting the lithium nickel cobalt manganese oxide cathode material to water absorption treatment, reacting it with a haloalkane; The haloalkane is a monohalide, and the halogen element in the haloalkane is selected from at least one of fluorine, chlorine, and bromine.

2. The preparation method according to claim 1, characterized in that, The haloalkane is selected from at least one of fluoromethane, fluoroethane, chloromethane, chloroethane, bromomethane, and bromoethane.

3. The preparation method according to claim 1, characterized in that, The process of the water absorption treatment includes: placing the lithium nickel cobalt manganese oxide cathode material in a humid environment with a humidity greater than or equal to 50% for placement.

4. The preparation method according to claim 3, characterized in that, The humidity of the humid environment is 60%-80%.

5. The preparation method according to claim 3, characterized in that, The placement time of the lithium nickel cobalt manganese oxide cathode material in the humid environment is 5h-8h.

6. The preparation method according to any one of claims 1-5, characterized in that, During the reaction with the haloalkane, control the reaction temperature to be 30°C-50°C and the reaction time to be 2h-8h.

7. The preparation method according to claim 6, characterized in that, During the reaction with the haloalkane, control the reaction temperature to be 35°C-45°C and the reaction time to be 2h-5h.

8. The preparation method according to claim 6, characterized in that, When the dosage of the lithium nickel cobalt manganese oxide cathode material is 1.0 kg, the inlet flow rate of the haloalkane gas is 0.05 L / min-0.15 L / min.

9. The preparation method according to claim 1, characterized in that, Place the lithium nickel cobalt manganese oxide cathode material in a tubular furnace, introduce water vapor into the tubular furnace to make the humidity in the tubular furnace meet the requirements, stop introducing water vapor after placing for 4h-10h, and introduce haloalkane gas for reaction after heating to the reaction temperature.

10. The preparation method according to claim 9, characterized in that, Before introducing water vapor into the tubular furnace, first introduce an inert gas to exhaust the air in the tubular furnace.

11. The preparation method according to claim 9, characterized in that, The water vapor enters the tubular furnace in a jet manner.

12. The preparation method according to claim 9, characterized in that, When the used haloalkane contains chlorine or bromine, the preparation method further includes: purging the obtained product after the reaction with the haloalkane is completed.

13. The preparation method according to claim 1, characterized in that, The chemical formula of the lithium nickel cobalt manganese oxide cathode material is LiNi x Co y Mn z O 2 , where 0.7 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.15, 0.05 ≤ z ≤ 0.15, and x + y + z = 1.

14. The preparation method according to claim 13, characterized in that, The lithium nickel cobalt manganese oxide cathode material is in powder form, and the average particle size of the powder is 2μm-15μm.

15. The preparation method according to claim 1, characterized in that, The preparation method of the lithium nickel cobalt manganese oxide cathode material includes: mixing a nickel cobalt manganese ternary precursor with a lithium source, performing a first calcination in an oxygen-containing atmosphere to obtain a first calcined product, and then performing a second calcination on the first calcined product in an oxygen-containing atmosphere.

16. The preparation method according to claim 15, characterized in that, the calcination temperature of the first calcination is 500°C - 600°C, and the calcination time is 4h - 7h.

17. The preparation method according to claim 15, characterized in that, the calcination temperature of the second calcination is 700°C - 800°C, and the calcination time is 10h - 18h.

18. The preparation method according to claim 15, characterized in that, by controlling the amounts of the nickel-cobalt-manganese ternary precursor and the lithium source, the molar ratio of the total amount of nickel, cobalt and manganese to the lithium element is 1:(1.01 - 1.20).

19. The preparation method according to claim 15, characterized in that, the lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

20. The preparation method according to claim 15, characterized in that, before the first calcined product is subjected to the second calcination, the first calcined product is cooled and then pulverized to 2μm - 15μm.

21. A ternary cathode material, characterized in that, it is prepared by the preparation method according to any one of claims 1 - 20.

22. A positive electrode sheet for a lithium-ion battery, characterized in that, it includes a positive electrode current collector and an active coating adhered to the positive electrode current collector, and the active coating contains the ternary cathode material according to claim 21.

23. A lithium-ion battery, characterized in that, it includes the positive electrode sheet for a lithium-ion battery according to claim 22.

24. An electrical device, characterized in that, it includes the lithium-ion battery according to claim 23.

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