A functionalized modified coating agent, its preparation method and application

Abstract

The present invention discloses a functionalized modified coating agent, a preparation method and an application thereof. The modified coating agent comprises wLiNi x Co y Mn (1‑x‑y) O 2 ·(1 - w)Li a M b O c ; wherein, Li a M b O c is a coating layer, and oxides are accompanied on the coating layer; 0.3 ≤ x ≤ 1, y ≥ 0, and 1 - x - y ≥ 0; M is selected from at least one of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium; 0 < w < 1, a > 0, b > 0, c > 0; the oxides include oxides of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium. The above functionalized modified coating agent has a narrow particle size distribution, small and fluffy particles, and its fluffy and light quality is beneficial to form a uniform coating on the ternary cathode substrate.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium - ion batteries, and particularly relates to a functionalized modified coating agent, a preparation method thereof, and an application thereof. Background Art

[0002] In the field of electric vehicles, people generally care about the driving range and safety performance of electric vehicles. The most critical component of an electric vehicle is the lithium - ion battery. A lithium - ion battery generally consists of a positive electrode, a negative electrode, a separator, and an electrolyte. Among them, the performance of the positive electrode material directly determines the energy density, safety performance, and service life of the lithium - ion battery.

[0003] Currently, intercalation lithium compounds are generally used for the positive electrode of lithium - ion batteries, such as LiMn 2 O 4 、LiFePO 4 、LiCoO 2 、ternary positive electrode material Li( Ni x Co y Mn z ) O 2 . Among them, the ternary positive electrode material has become the research focus of major battery manufacturers due to its higher energy density advantage. However, the layered structure of the ternary positive electrode material is unstable and needs to be stabilized by other modification means. Among these, coating is a relatively common and effective method.

[0004] Traditional coating agents include metal oxides, graphene, phosphates, and conductive polymers, etc. However, their functions are relatively single, it is difficult to have both electron - conducting and ion - conducting properties, and it is difficult to provide large capacity, large particle size distribution, and easy caking. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is:

[0006] To provide a functionalized modified coating agent.

[0007] This functionalized modified coating agent has both electron - conducting and ion - conducting properties and can be used as a coating agent for ternary positive electrode materials.

[0008] The second technical problem to be solved by the present invention is:

[0009] To provide a preparation method of the functionalized modified coating agent.

[0010] The third technical problem to be solved by the present invention is:

[0011] The application of the functionalized modified coated lithium - ion positive electrode material.

[0012] To solve the first technical problem, the technical solution adopted by the present invention is:

[0013] The modified coating agent includes wLiNi x Co y Mn (1-x-y) O 2 ·(1 - w)Li a M b O c ;

[0014] Wherein, Li a M b O c is the coating layer, and oxides are accompanied on the coating layer;

[0015] 0.3 ≤ x ≤ 1, y ≥ 0, and 1 - x - y ≥ 0;

[0016] M is selected from at least one of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium;

[0017] 0 < w < 1, a > 0, b > 0, c > 0;

[0018] The oxides include oxides of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium.

[0019] The particle size of the functionalized modified coating agent is 0.11μm - 0.63μm.

[0020] The functionalized modified coating agent is very fluffy and light, with fine particles and a narrow particle size distribution, which is beneficial to form a uniform coating on the ternary cathode substrate.

[0021] The particles of the functionalized modified coating agent are fine, the particle size is preferably about 200nm, the particle coating layer thickness is about 47nm, which synergizes with the core ternary micro - powder to improve the ion - conducting and electron - conducting properties of the coating agent and can provide a certain capacity.

[0022] In the preparation method of the functionalized modified coating agent, the ternary micro - powder LiNi x Co y Mn (1-x-y) O 2 reacts violently with metal salts, fuels, and additives under low - temperature combustion, and a ternary micro - powder / metal salt core - shell structure composite product is generated by the self - propagating sol - gel method, and further calcined to obtain the functionalized modified coating agent. The rough metal salt shell layer helps to improve the BET and surface energy of the functionalized modified coating agent, making it easier to adhere to the surface of the ternary material substrate and not prone to displacement and agglomeration. The rough shell layer acts as a binder at a certain temperature and effectively fuses the ternary micro - powder to the substrate surface, improving the coating uniformity of the coating agent.

[0023] To solve the second technical problem, the technical solution adopted in the present invention is:

[0024] A method for preparing the functionalized modified coating agent includes the following steps:

[0025] Mix ternary micropowder LiNi x Co y Mn (1-x-y) O 2 , a metal salt, a fuel, and an auxiliary agent in a solvent, dry to obtain a dry gel, and burn the dry gel to obtain the functionalized modified coating agent.

[0026] According to an embodiment of the present invention, the ternary micropowder LiNi x Co y Mn (1-x-y) O 2 is preferably the recycled material of the cathode micropowder.

[0027] The burning includes low-temperature combustion and high-temperature calcination.

[0028] During the low-temperature combustion process, a large amount of gas is generated, thereby obtaining a fluffy product and a layer of rough oxides coated on the product.

[0029] The high-temperature calcination is mainly used to remove residual organic matter.

[0030] According to an embodiment of the present invention, dissolve the ternary micropowder LiNi x Co y Mn (1-x-y) O 2 in an organic solvent, and through the high-speed rotation of the eccentric disc of the stirring shaft, drive the material and the grinding medium to have an efficient relative movement to obtain a micropowder dispersion.

[0031] According to an embodiment of the present invention, a method for preparing the functionalized modified coating agent includes the following steps:

[0032] Dissolve the metal salt, the fuel, and the auxiliary agent in a solvent to obtain a mixed solution.

[0033] Add the mixed solution to the micropowder dispersion, stir and evaporate in a water bath to obtain a black viscous liquid, transfer it to an oven to dry to form a loose and porous dry gel;

[0034] Ignite the dry gel to obtain a light product, and then calcine to remove residual organic matter to prepare the modified coating agent.

[0035] According to an embodiment of the present invention, the grinding is preferably wet grinding.

[0036] Wet grinding means that the material enters the grinding chamber under the action of a feed pump. Through the high-speed rotation of the eccentric disc of the stirring shaft, the material and the grinding medium have an efficient relative movement. The solid particles of the material are effectively dispersed, sheared and ground. After passing through the dynamic large-flow rotor gap separation filter, a narrow particle size particle dispersion liquid is obtained.

[0037] According to an embodiment of the present invention, the organic solvent includes at least one of n-octane, n-heptane, dodecane, ethanol, and acetone.

[0038] According to an embodiment of the present invention, the mass ratio of the organic solvent to LiNi x Co y Mn (1-x-y) O 2 is (0.1-100):1.

[0039] According to an embodiment of the present invention, the grinding method is at least one of wet grinding, ball milling, jet milling, and mechanical grinding.

[0040] According to an embodiment of the present invention, the grinding time is 0.1h to 6h.

[0041] According to an embodiment of the present invention, the rotation speed of the eccentric disc of the stirring shaft is 500 to 4000 rpm.

[0042] According to an embodiment of the present invention, the particle size D50 of the fine powder dispersion liquid is 0.1 to 1 μm.

[0043] According to an embodiment of the present invention, the particle size D99 of the fine powder dispersion liquid is 0.3 to 2 μm.

[0044] D50 and D90 are parameters of the particle size, and the meanings they represent are that 50% and 90% of the particle sizes are within the measured size values.

[0045] The LiNi x Co y Mn (1-x-y) O 2 can be selected from the ternary fine powder LiNi x Co y Mn (1-x-y) O 2 recycled materials generated additionally during the industrial production process.

[0046] According to an embodiment of the present invention, the temperature of the water bath evaporation is 60 to 95 °C, and it can also be an oil bath.

[0047] According to an embodiment of the present invention, the oven drying temperature is 100 to 150 °C, and the drying time is 12 to 48 h.

[0048] According to an embodiment of the present invention, the calcination is carried out in a tubular furnace.

[0049] According to an embodiment of the present invention, the calcination temperature of the tubular furnace is 400 - 800 °C, the heating rate is 1 - 10 °C / min, the calcination atmosphere is air or oxygen, and the time is 1 - 8 h.

[0050] According to an embodiment of the present invention, the coating agent is prepared by the following reaction:

[0051] LiNi x Co y Mn (1-x-y) O 2 +4Co(NO 3 ) 2 ·6H 2 O+2Ce(NO 3 ) 3 ·6H 2 O+2C 6 H 8 O 7 +2C 2 H 3 LiO 2 +C 6 H 12 N 4 +14O 2 →LiNi x Co y Mn (1-x-y) O 2 ·Li 2 (Co 2 Ce)O 6 +Co 2 O 3 +CeO 2 +2N 2 +6NO +8NO 2 +22CO 2 +47H 2 O.

[0052] Reaction conditions: Ignite in air at ≥200 °C.

[0053] According to an embodiment of the present invention, the metal salt includes at least one of cobalt nitrate, cerium nitrate, nickel nitrate, manganese nitrate, aluminum nitrate, zirconium nitrate, yttrium nitrate, strontium nitrate.

[0054] According to a preferred embodiment of the present invention, the metal salt further includes lithium acetate. The lithium acetate has a low melting point and can be dissolved at about 280 °C, acting as a reducing agent in the reaction and providing part of the lithium source.

[0055] The metal salt is mainly selected from nitrates, enabling the metal salt to react rapidly at low temperatures and generate a large amount of gas, thereby obtaining a light and delicate functionalized modified coating agent. This functionalized modified coating agent has a narrow particle size distribution, small and fluffy particles, and its light and fluffy nature is conducive to forming a uniform coating on the ternary cathode substrate when used as a coating material.

[0056] The metal salt can also be a non - nitrate, but nitrates should be the main component in the metal salt. Other metal salts do not have the effect of rapidly reacting at low temperatures to generate gas and obtaining a light and fluffy product.

[0057] According to one embodiment of the present invention, the fuel includes at least one of lithium acetate, citric acid, urea, and glycine.

[0058] According to one embodiment of the present invention, the auxiliary agent includes at least one of hexamethylenetetramine, sodium dodecylbenzenesulfonate, and cetyltrimethylammonium bromide.

[0059] The auxiliary agent is preferably hexamethylenetetramine. As a surfactant and emulsifier, hexamethylenetetramine mainly enables the fine powder dispersion liquid obtained by dispersing LiNi x Co y Mn (1-x-y) O 2 in an organic solvent, and the emulsion dispersion with a nitrate solution to obtain an emulsion, and then further drying to obtain a porous xerogel, which helps to ignite and undergo low - temperature combustion.

[0060] When the auxiliary agent is not hexamethylenetetramine, it is easy to introduce impurity elements such as Na, S, and Br into the product.

[0061] According to one embodiment of the present invention, the mass ratio of LiNi x Co y Mn (1-x-y) O 2 to the sum of the masses of the metal salt, the fuel, and the auxiliary agent is (0.01 - 1):1.

[0062] In the preparation method of the functionalized modified coating agent, the mass ratio of the ternary fine powder LiNi x Co y Mn (1-x-y) O 2 to the sum of the masses of the metal salt, the fuel, and the auxiliary agent is within a suitable range, enabling the reaction to proceed normally and fully, thereby inhibiting the generation of by - products.

[0063] If the proportion of the metal salt is too large, the low - temperature combustion reaction will not be able to proceed.

[0064] Ternary fine powder LiNi x Coy Mn (1-x-y) O 2 The quality of should not be excessive either, because if LiNi that does not participate in the low-temperature combustion reaction x Co y Mn (1-x-y) O 2 is excessive, then the low-temperature combustion reaction will not be able to proceed.

[0065] According to an embodiment of the present invention, the particle size of the ternary micropowder LiNi x Co y Mn (1-x-y) O 2 is 0.1 - 2 μm.

[0066] According to an embodiment of the present invention, the temperature of the combustion is 200 - 400 °C.

[0067] According to an embodiment of the present invention, the time of the combustion is less than 1 minute.

[0068] Another aspect of the present invention also relates to the application of the functionalized modified coating agent in a battery.

[0069] One of the technical solutions in the above technical solutions has at least one of the following advantages or beneficial effects:

[0070] 1. The metal salt is mainly selected as nitrate, so that the metal salt can react quickly at low temperature and generate more gas, thereby obtaining a light and delicate functionalized modified coating agent. The particle size distribution of this functionalized modified coating agent is narrow, the particles are small and fluffy, and its light and fluffy nature is conducive to forming a uniform coating on the ternary cathode substrate.

[0071] 2. The particles of the functionalized modified coating agent are delicate, the particle size is about 200 nm, and the thickness of the particle coating layer is about 50 nm. It synergizes with the core ternary micropowder to improve the ion conduction and electron conduction performance of the coating agent and can provide a certain capacity.

[0072] 3. Lithium acetate in the fuel has a low melting point and can be dissolved at about 280 °C. It acts as a reducing agent together with the other fuels during the low-temperature combustion reaction and provides part of the lithium source.

[0073] 4. In the preparation method of the functionalized modified coating agent, the mass ratio of the ternary micropowder LiNi x Co y Mn (1-x-y) O 2 to the sum of the masses of the metal salt, the fuel and the auxiliary agent is within a suitable range, so that the reaction can proceed normally and fully, thereby inhibiting the generation of by-products.

[0074] 5. In the preparation method of the functionalized modified coating agent, the ternary micro-powder LiNi x Co y Mn (1-x-y) O 2 reacts violently with metal salts, fuels and additives under low-temperature combustion, and the ternary micro-powder / metal salt core-shell structure composite product is generated by the self-propagating sol-gel method, and further calcined to obtain the functionalized modified coating agent. The rough metal salt shell layer helps to improve the BET and surface energy of the functionalized modified coating agent, making it easier to adhere to the surface of the ternary material substrate and not prone to displacement and agglomeration. The rough shell layer acts as a binder at a certain temperature and fuses the functionalized modified coating agent to the substrate surface, improving the coating uniformity of the coating agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0076] Figure 1 It is the XRD pattern of the functionalized modified coating agent of Example 1.

[0077] Figure 2 It is the SEM comparison diagram of various coating agents. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0078] To describe in detail the technical content, the achieved objectives and effects of the present invention, the following is described in conjunction with the embodiments.

[0079] The embodiments are all designed with reference to the following functionalized modified coating agent synthesis reaction equation, and the raw materials and key parameters are shown in Table 1:

[0080] LiNi x Co y Mn (1-x-y) O 2 +4Co(NO 3 ) 2 ·6H 2 O+2Ce(NO 3 ) 3 ·6H 2 O+2C 6 H 8 O 7 +2C 2 H 3 LiO 2 +C 6 H 12 N 4 +14O 2 → LiNi x Coy Mn (1-x-y) O 2 ·Li 2 (Co 2 Ce)O 6 +Co 2 O 3 +CeO 2 +2N 2 +6NO +8NO 2 +22CO 2 +47H 2 O。

[0081] Table 1 Design of Example Schemes

[0082]

[0083] Example 1

[0084] Functionalized Modified Coating Agent A preparation method of a functionalized modified coating agent includes the following specific steps:

[0085] (1) Disperse 4.828 g of ternary micropowder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.5 Co 0.2 Mn 0.3 O 2 into 60 mL of dodecane oily liquid, and drive the micropowder and grinding medium to perform efficient relative movement through the high-speed rotation of the eccentric disk of the stirring shaft to obtain a micropowder dispersion liquid. The rotation speed of the eccentric disk of the stirring shaft is 3000 rpm, and the grinding time is 4 h.

[0086] (2) Weigh 116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate, and 14.006 g of hexamethylenetetramine, and add them step by step to 200 mL of deionized water, and stir and dissolve to obtain a mixed solution.

[0087] (3) Drop the micropowder dispersion liquid in step (1) into step (2), stir ultrasonically at room temperature for 2 h to obtain an emulsion, evaporate the water and organic solvents in a water bath at 80 °C to obtain a black viscous liquid, transfer it to an oven at 120 °C and dry it for 24 h to obtain a dry gel;

[0088] (4) Heat the dry gel in step (3) to 235 °C to ignite it. After intense combustion for dozens of seconds, obtain a light product, transfer it to a tubular furnace, and calcine it at 600 °C for 4 h in a nitrogen atmosphere to remove residual organic matter and prepare a functionalized modified coating agent.

[0089] The mass of the above functionalized modified coating agent is 23.22 g.

[0090] The structural formula of the above functionalized modified coating agent is as follows:

[0091] LiNi 0.5 Co 0.2 Mn 0.3 O 2 ·2Li 2 (Co 2 Ce)O 6 .

[0092] Example 2

[0093] A preparation method of a functionalized modified coating agent, including the following specific steps:

[0094] (1) Disperse 9.656 g of ternary micropowder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.5 Co 0.2 Mn 0.3 O 2 into 60 mL of dodecane oily liquid, and drive the micropowder and the grinding medium to perform a high-efficiency relative movement through the high-speed rotation of the stirring shaft eccentric disc to obtain a micropowder dispersion liquid. The rotation speed of the stirring shaft eccentric disc is 3000 rpm, and the grinding time is 4 h.

[0095] (2) Weigh 116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate, and 14.006 g of hexamethylenetetramine, and add them step by step to 200 mL of deionized water, and stir and dissolve to obtain a mixed solution.

[0096] (3) Drop the above micropowder dispersion liquid in step (1) into step (2), stir ultrasonically at room temperature for 2 h to obtain an emulsion, evaporate the water and organic solvents in a water bath at 80 °C to obtain a black viscous liquid, transfer it to an oven at 120 °C and dry it for 24 h to obtain a dry gel;

[0097] (4) Heat the above dry gel in step (3) to 250 °C to ignite it. After intense combustion for dozens of seconds, obtain a light product, transfer it to a tubular furnace, and calcine it at 600 °C for 4 h in a nitrogen atmosphere to remove the residual organic matter, and prepare the above functionalized modified coating agent.

[0098] The mass of the above functionalized modified coating agent is 46.44 g.

[0099] The structural formula of the above functionalized modified coating agent is as follows:

[0100] LiNi 0.5 Co 0.2 Mn 0.3 O 2 ·Li 2 (Co 2 Ce)O6 。

[0101] Example 3

[0102] Functionalized modified coating agent A preparation method of a functionalized modified coating agent includes the following specific steps:

[0103] (1) Disperse 19.312 g of ternary micropowder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.5 Co 0.2 Mn 0.3 O 2 into 60 mL of dodecane oily liquid, and drive the micropowder and the grinding medium to perform a high-efficiency relative movement through the high-speed rotation of the eccentric disk of the stirring shaft to obtain a micropowder dispersion liquid. The rotation speed of the eccentric disk of the stirring shaft is 3000 rpm, and the grinding time is 4 h.

[0104] (2) Weigh 116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate, and 14.006 g of hexamethylenetetramine, and add them step by step to 200 mL of deionized water, and stir and dissolve to obtain a mixed solution.

[0105] (3) Drop the micropowder dispersion liquid in step (1) into step (2), stir ultrasonically at room temperature for 2 h to obtain an emulsion, evaporate the water and organic solvents in a water bath at 80 °C to obtain a black viscous liquid, transfer it to an oven at 120 °C and dry it for 24 h to obtain a dry gel;

[0106] (4) Heat the dry gel in step (3) to 235 °C to ignite it. After intense combustion for dozens of seconds, obtain a light product, transfer it to a tubular furnace, and calcine it at 290 °C for 4 h in a nitrogen atmosphere to remove residual organic matter, and prepare the above functionalized modified coating agent.

[0107] The mass of the above functionalized modified coating agent is 32.88 g.

[0108] The coating thickness of the above functionalized modified coating agent is 47 nm.

[0109] The structural formula of the above functionalized modified coating agent is:

[0110] 2LiNi 0.5 Co 0.2 Mn 0.3 O 2 ·Li 2 (Co 2 Ce)O 6 。

[0111] Example 4

[0112] Functionalized modified coating agent A preparation method of a functionalized modified coating agent includes the following specific steps:

[0113] (1) Disperse 9.589 g of ternary micropowder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.33 Co 0.33 Mn 0.33 O 2 into 60 mL of dodecane oily liquid, and drive the micropowder and the grinding medium to perform a high-efficiency relative movement through the high-speed rotation of the stirring shaft eccentric disk to obtain a micropowder dispersion liquid. The rotation speed of the stirring shaft eccentric disk is 3000 rpm, and the grinding time is 4 h.

[0114] (2) Weigh 116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate, and 14.006 g of hexamethylenetetramine, and add them step by step to 200 mL of deionized water, and stir and dissolve to obtain a mixed solution.

[0115] (3) Drop the micropowder dispersion liquid in step (1) into step (2), and ultrasonically stir at room temperature for 2 h to obtain an emulsion. Evaporate the water and organic solvents in a water bath at 80 °C to obtain a black viscous liquid, transfer it to an oven at 120 °C and dry it for 24 h to obtain a dry gel;

[0116] (4) Heat the dry gel in step (3) to 250 °C to ignite it. After intense combustion for dozens of seconds, obtain a light product, transfer it to a tube furnace, and calcine it at 600 °C for 4 h under a nitrogen atmosphere to remove the residual organic matter, and prepare the above functionalized modified coating agent.

[0117] The mass of the above functionalized modified coating agent is 46.37 g.

[0118] The structural formula of the above functionalized modified coating agent is:

[0119] LiNi 0.33 Co 0.33 Mn 0.33 O 2 ·Li 2 (Co 2 Ce)O 6 .

[0120] Example 5

[0121] Functionalized modified coating agent A preparation method of a functionalized modified coating agent includes the following specific steps:

[0122] (1) Disperse 9.589 g of ternary micropowder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.8 Co 0.1 Mn 0.1 O 29.728 g of the ternary fine powder was dispersed into 60 mL of dodecane oily liquid, and the high-speed rotation of the eccentric disk of the stirring shaft was used to drive the efficient relative movement of the fine powder and the grinding medium to obtain a fine powder dispersion liquid. The rotation speed of the eccentric disk of the stirring shaft was 3000 rpm, and the grinding time was 4 h.

[0123] (2)116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate, and 14.006 g of hexamethylenetetramine were weighed and added step by step to 200 mL of deionized water, and stirred and dissolved to obtain a mixed solution.

[0124] (3)The above-mentioned fine powder dispersion liquid in step (1) was dropped into step (2), and ultrasonically stirred at room temperature for 2 h to obtain an emulsion. The water and organic solvents were evaporated in a water bath at 80 °C to obtain a black viscous liquid, which was transferred to an oven at 120 °C and dried for 24 h to obtain a dry gel;

[0125] (4)The above-mentioned dry gel in step (3) was heated to 250 °C to be ignited, and a light product was obtained after intense combustion for dozens of seconds. It was transferred to a tube furnace and calcined at 600 °C for 4 h in a nitrogen atmosphere to remove residual organic matter, and the above-mentioned functionalized modified coating agent was prepared.

[0126] The mass of the above-mentioned functionalized modified coating agent was 46.21 g.

[0127] The structural formula of the above-mentioned functionalized modified coating agent is:

[0128] LiNi 0.8 Co 0.1 Mn 0.1 O 2 ·Li 2 (Co 2 Ce)O 6 。

[0129] Comparative Example 1

[0130] (1)96.561 g of the ternary fine powder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.5 Co 0.2 Mn 0.3 O 2 was dispersed into 120 mL of dodecane oily liquid, and the high-speed rotation of the eccentric disk of the stirring shaft was used to drive the efficient relative movement of the fine powder and the grinding medium to obtain a fine powder dispersion liquid. The rotation speed of the eccentric disk of the stirring shaft was 3000 rpm, and the grinding time was 4 h.

[0131] (2) Weigh 116.376 g of cobalt nitrate hexahydrate, 86.826 g of cerium nitrate hexahydrate, 20.392 g of lithium acetate dihydrate, 42.024 g of citric acid monohydrate and 14.006 g of hexamethylenetetramine, and add them step by step to 200 mL of deionized water. Stir and dissolve to obtain a mixed solution.

[0132] (3) Drop the above-mentioned micro-powder dispersion liquid in step (1) into step (2), stir ultrasonically at room temperature for 2 h to obtain an emulsion. Evaporate the water and organic solvents in a water bath at 80 °C to obtain a black viscous liquid, transfer it to an oven at 120 °C and dry it for 24 h to obtain a dry gel.

[0133] (4) Transfer the above-mentioned dry gel in step (3) to a tubular furnace, calcine it at 600 °C for 4 h under a nitrogen atmosphere, and grind it to obtain a coating agent.

[0134] Among them, the above-mentioned dry gel in step (3) cannot be ignited and can only be calcined in a tubular furnace.

[0135] Comparative Example 2

[0136] (1) Mix 96.561 g of ternary micro-powder with a particle size D50 = 2 μm and a molecular formula of LiNi 0.5 Co 0.2 Mn 0.3 O 2 with 116.376 g of cobalt chloride hexahydrate, 86.826 g of cerium chloride hexahydrate, and 8.390 g of lithium hydroxide monohydrate by ball milling. The ball-to-material ratio is 1:1 and the ball milling time is 2 h to obtain a uniform mixture.

[0137] (2) Transfer the above-mentioned ball-milled mixture in step (1) to a tubular furnace, calcine it at 600 °C for 4 h under a nitrogen atmosphere, and grind and screen it to obtain a coating agent.

[0138] Among them, there is an explosion risk for nitrates in step (1), so chlorides are used as the cobalt source and cerium source.

[0139] Performance test:

[0140] Table 2 shows the particle size data of the functionalized modified coating agents prepared in Examples 1, 2, and 3, and the coating agents prepared in Comparative Examples 1 and 2. The specific data were obtained by testing with a Mastersizer 3000 device.

[0141] As can be seen from Table 2, the particle size distribution of the functionalized modified coating agents prepared in the examples is relatively narrow. Especially in Example 1, the small particle size and narrow distribution are beneficial to the formation of a uniform coating of the coating agent on the substrate.

[0142] On the contrary, the particle size of Comparative Example 1 is large and the distribution is wide. This is because the content of ternary fine powder is too much and it cannot be ignited. After calcination, the particles are seriously agglomerated and need to be ground. The relatively wide particle size is not conducive to the coating effect. Therefore, the content of fine powder should not be too much.

[0143] The particle size of Comparative Example 2 is even wider and it cannot be used as a coating agent.

[0144] Table 2 Particle size distribution of functionalized modified coating agent

[0145]

[0146] Table 3 shows the impurity element contents of the functionalized modified coating agents prepared in Examples 1, 2, and 3, and the coating agent prepared in Comparative Example 1. The specific data were obtained by testing with an ICP-AES device.

[0147] As can be seen from Table 3, the impurity contents of the functionalized modified coating agents prepared in Examples 1-3 and Comparative Example 1 are all less. This shows that the organic matter has been basically removed through calcination.

[0148] Table 3 Impurity contents of functionalized modified coating agent

[0149]

[0150] Table 4 shows the BET (specific surface area measurement method), loose bulk density, and tapped density test data of the functionalized modified coating agents prepared in Examples 1, 2, and 3, and the coating agent prepared in Comparative Example 1. The specific data were obtained by testing with a Micromeritics TriStAr II 3020 device and a Dandong BET BT-302 tapped density meter.

[0151] As can be seen from Table 4, the BET of the functionalized modified coating agents prepared in Examples 1-3 is larger, while the loose bulk density and tapped density are smaller.

[0152] On the contrary, the BET of Comparative Example 1 is smaller, while the loose bulk density and tapped density are both larger. Since Comparative Example 1 cannot undergo low-temperature combustion, it can be shown from the data in Table 4 that a fluffy ultrafine lightweight coating agent can be obtained through low-temperature combustion.

[0153] Table 4 BET, loose bulk density, and tapped density of functionalized modified coating agent

[0154]

[0155] Table 5 shows the electrochemical performance test data of the functionalized modified coating agents prepared in Examples 1, 2, and 3, and the coating agents prepared in Comparative Examples 1 and 2. The specific data were obtained by testing with an electric button cell tester.

[0156] As can be seen from Table 5, the functionalized modified coating agents prepared in Examples 1, 2, and 3 have a certain specific capacity.

[0157] In Comparative Examples 1 and 2, the discharge efficiency was low because the coating agent agglomerated and a thick layer of residual lithium was wrapped on the surface, severely restricting the entry and exit of lithium ions.

[0158] Table 5 Electrochemical Performance of Functionalized Modified Coating Agent

[0159]

[0160] The test conditions for the above electrochemical performance were as follows: the rate was 0.1C, the voltage was 4.35V, the test temperature was 25°C, the negative electrode material was graphite, the electrolyte was fluoroethylene carbonate, the separator was a PP / PE / PP multi-layer composite microporous membrane, and the loading amount of the active material was 0.8g.

[0161] Since the reason for the low charge capacity in the examples of the present invention is that the content of the active material in the positive electrode material is low due to the surface coating layer, the charge specific capacity is lower than that of the comparative examples.

[0162] The above Figure 1 is the XRD pattern of the functionalized modified micro-powder coating agent. From Figure 1 it can be seen that a weak diffraction peak appears near the diffraction angle of 30°, and the corresponding substance is CeO 2 , and this CeO 2 is a by-product.

[0163] Figure 2 is the SEM comparison diagram of various coating agents.

[0164] Among them, Figure 2 (a)SEM image of the ternary micro-powder of the positive electrode material. Figure 2 (b)SEM image of the functionalized modified coating agent prepared in Example 1. Figure 2 (c)SEM image of the section of Example 1. Figure 2 (d)SEM image of the coating agent of Comparative Example 1.

[0165] From Figure 2 (b), it can be seen that the particle size of the functionalized modified coating agent in Example 1 is about 200nm, and a layer of substance is coated on the surface, which can increase the activity of the micro-powder coating agent and help to coat it on the surface of the substrate.

[0166] The above-mentioned surface-coated substance is Co 2 O 3 , CeO 2 , Li 2 (Co 2 Ce)O 6 generated by low-temperature combustion reaction. The above-mentioned surface-coated substance itself also belongs to the coating agent.

[0167] By coating a rough substance, it helps to improve the BET and surface energy of the ternary micro-powder, making it easier for the ternary micro-powder coating agent to adhere to the substrate surface and less likely to displace and agglomerate. The surface coating layer acts as a binder at a certain temperature and fuses the micro-powder coating agent to the substrate surface.

[0168] From Figure 2 As can be seen from (d), no obvious rough coating layer appears on the surface of the coating agent particles in Comparative Example 1. On the contrary, the particles are severely agglomerated, and the particles are connected by a layer of residual lithium.

[0169] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made by using the content of the specification of the present invention, directly or indirectly applied in the related technical field, is equally included in the patent protection scope of the present invention.

Claims

1. A functionalized modified coating agent, Characterized in that: The modified coating agent includes wLiNi x Co y Mn (1-x-y) O 2 ·(1 - w)Li a M b O c ; Among them, Li a M b O c is the coating layer, and oxides accompany on the coating layer; 0.3 ≤ x ≤ 1, y ≥ 0, and 1 - x - y ≥ 0; M is selected from at least one of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium; 0 < w < 1, a > 0, b > 0, c > 0; The oxides include oxides of cobalt, cerium, nickel, manganese, aluminum, zirconium, strontium, and yttrium; The particle size of the functionalized modified coating agent is 0.11 μm - 0.63 μm; The functionalized modified coating agent is prepared by the following method, including the following steps: Mix ternary fine powder LiNi x Co y Mn (1-x-y) O 2 , metal salts, fuels and additives in a solvent, dry to obtain a xerogel, and burn the xerogel to obtain the functionalized modified coating agent; The combustion includes low-temperature combustion and high-temperature calcination. The temperature of low-temperature combustion is 200 - 400 °C, and the temperature of high-temperature calcination is 400 - 800 °C; The metal salts include at least one of cobalt nitrate, cerium nitrate, nickel nitrate, manganese nitrate, aluminum nitrate, zirconium nitrate, yttrium nitrate, and strontium nitrate; The auxiliary agent includes hexamethylenetetramine.

2. The functionalized modified coating agent according to claim 1, Characterized in that: The oxide includes Co 2 O 3 、 Co 3 O 4 、 CeO 2 、 Ce 2 O 3 、 NiO, MnO, Al 2 O 3 、 ZrO, Y 2 O 3 and at least one of SrO.

3. The functionalized modified coating agent according to claim 1, Characterized in that: The metal salts further include lithium acetate.

4. The functionalized modified coating agent according to claim 1, Characterized in that: The fuels include at least one of lithium acetate, citric acid, urea, and glycine.

5. The functionalized modified coating agent according to claim 1, Characterized in that: The auxiliary agent further includes at least one of sodium dodecylbenzenesulfonate or cetyltrimethylammonium bromide.

6. The functionalized modified coating agent according to claim 1, Characterized in that: It further includes the following steps: Dissolve the LiNi x Co y Mn (1-x-y) O 2 in a solvent, and the mass ratio of the solvent to LiNi x Co y Mn (1-x-y) O 2 is (10 - 100):

1.

7. Application of the functionalized modified coating agent according to any one of claims 1 - 2 in a battery.

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