Ceramic slurry, preparation method thereof and positive plate

Abstract

The invention provides ceramic slurry. The ceramic slurry is prepared from the following raw materials in parts by weight: 59.7 to 50.3 parts of an organic solvent, 1.994 to 2.006 parts of a first binder, 7.976 to 8.024 parts of a photothermal conversion agent, 4.985 to 5.015 parts of a second binder and 34.896 to 35.105 parts of ceramic powder, the photothermal conversion agent is coal pitch carbon dots. The first binder can be better combined with the coal pitch carbon dots, a layer of protective film can be formed on the surfaces of the coal pitch carbon dots, the structure of the coal pitch carbon dots is prevented from being damaged, the coal pitch carbon dots have the semiconductor characteristic and excellent photo-thermal performance, the light sensitivity is high, light can be absorbed and converted into heat energy more easily, and the service life of the coal pitch carbon dots is prolonged. Therefore, when the tab is cut under the irradiation of the continuous laser, the laser can be absorbed and converted into heat energy, so that hot spots are formed on the surface of the ceramic slurry, the tab can be cut off, the phenomenon that the ceramic slurry is associated in the laser cutting process can be avoided, the equipment cost and the production energy consumption are reduced, and the product percent of pass is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a ceramic slurry preparation method and a positive electrode sheet. Background Art

[0002] Lithium-ion batteries are widely used in energy storage and power battery industries due to their high operating voltage, high energy density, long cycle life and environmental protection. However, during the manufacturing process, poor overhang coating and membrane shrinkage during the baking process will increase the risk of short circuits. Therefore, during the manufacturing process of the positive electrode, a layer of ceramic slurry is applied near the material area to avoid this risk.

[0003] However, a new problem has been introduced. Currently, the positive electrode sheets in the industry often have problems with the tabs not being cut during the laser cutting process due to the ceramic coating, especially when using continuous lasers. Increasing the laser power or replacing the pulsed laser will increase costs and energy consumption, and the ceramic layer is prone to falling off during the cutting process. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to provide a ceramic slurry so that the positive electrode tab can be cut off when the positive electrode tab is cut using a continuous laser.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] The first aspect of the present invention provides a ceramic slurry, which includes the following raw materials in parts by weight: 59.7 to 50.3 parts of an organic solvent, 1.994 to 2.006 parts of a first binder, 7.976 to 8.024 parts of a photothermal conversion agent, 4.985 to 5.015 parts of a second binder and 34.896 to 35.105 parts of a ceramic powder; the photothermal conversion agent is coal tar pitch carbon dots.

[0007] Beneficial effects: The first binder in the present invention can better bond with coal tar pitch carbon dots, and can form a protective film on the surface of coal tar pitch carbon dots to prevent the structure of coal tar pitch carbon dots from being destroyed. The second binder plays a role of bonding and thickening, thereby improving the stability of the ceramic slurry. The present invention utilizes the semiconductor characteristics of coal tar pitch carbon dots and has excellent photothermal properties. It is highly sensitive to light and can more easily absorb and convert light into heat energy. Therefore, when cutting the pole ear under the irradiation of a continuous laser, the laser absorption can be converted into heat energy, so that a hot spot is formed on the surface of the ceramic slurry, thereby being able to cut off the pole ear, and can also avoid the phenomenon of ceramic slurry being carried over during the laser cutting process, thereby reducing equipment costs and production energy consumption, and improving product qualification rate.

[0008] The second aspect of the present invention provides a method for preparing the above-mentioned ceramic slurry, wherein an organic solvent, a first binder, a photothermal conversion agent, a second binder and ceramic powder are mixed and dispersed by a wet slurry mixing method and allowed to stand for defoaming to obtain a ceramic slurry.

[0009] Beneficial effects: The present invention adopts a wet slurrying method to add the photothermal conversion agent to the ceramic slurry. During the mixing and dispersing process, the uniformity of the photothermal conversion agent in the ceramic slurry is guaranteed. The first binder can form a protective film on the surface of the coal tar carbon dots to prevent the structure of the coal tar carbon dots from being destroyed, so that the ceramic slurry can form uniform hot spots under the irradiation of a continuous laser, thereby being able to cut off the pole ear, and can also avoid the ceramic slurry linkage phenomenon in the laser cutting process, reducing equipment costs and production energy consumption, and improving product qualification rate.

[0010] Preferably, the photothermal conversion agent is coal tar pitch carbon dots, and the preparation method thereof is as follows:

[0011] (1) ball milling the coal tar pitch solid to obtain a smaller-sized coal tar pitch powder;

[0012] (2) adding coal tar powder to a mixture of formic acid and hydrogen peroxide to react; after the reaction, centrifuging to remove large particles in the solution after the reaction to obtain a suspension containing carbon dots;

[0013] (3) The suspension containing carbon dots is subjected to rotary evaporation to remove the reaction liquid, thereby obtaining coal tar pitch carbon dots.

[0014] Preferably, the ceramic powder is boehmite powder, and the particle size of the boehmite powder is 400-500 nm.

[0015] Preferably, the first binder is one of methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate or hexyl methacrylate.

[0016] Preferably, the second binder is one of polyvinylidene fluoride, sodium carboxymethyl cellulose or polyacrylic acid.

[0017] Preferably, during the mixing and dispersing process, the revolution speed is 10 to 50 rpm / min, and the rotation speed is 800 to 1700 rpm / min.

[0018] Preferably, the standing defoaming time is 1 to 2 hours, and the standing defoaming temperature is 25 to 30°C.

[0019] A third aspect of the present invention provides a positive electrode sheet, comprising the above-mentioned ceramic slurry or the ceramic slurry prepared by the above-mentioned ceramic slurry preparation method, and the ceramic slurry is uniformly coated on the tab of the positive electrode sheet to obtain the positive electrode sheet.

[0020] Beneficial effect: The ceramic slurry provided by the present invention and the positive electrode prepared using the ceramic slurry can not only ensure the insulation performance of the electrode, but also due to the semiconductor characteristics of the photothermal converter and the excellent photothermal performance, it can convert the laser absorption into thermal energy under the irradiation of a low-power continuous laser, forming uniform hot spots on the surface of the ceramic slurry, thereby cutting off the pole ear, and also avoiding the ceramic slurry joint phenomenon in the laser cutting process, reducing equipment costs and production energy consumption, and improving product qualification rate.

[0021] Preferably, the coating width of the ceramic slurry is smaller than the width of the tab; the thickness of the ceramic slurry coated on one side is 25±2 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of coating the ceramic slurry obtained in Example 1 on the positive electrode sheet;

[0023] Figure 2 is a schematic diagram of coating the ceramic slurry obtained in Example 2 on the positive electrode sheet;

[0024] Markings in the figure: 1: positive electrode sheet, 2: material area, 3: pole ear; 4: ceramic area;

[0025] Figure 3 Spectral absorption diagrams of ceramic slurries obtained in Example 1, Comparative Example 1 and Comparative Example 2;

[0026] Figure 4 This is a picture of the positive electrode sheet obtained in Example 1 being cut with a 500W continuous laser;

[0027] Figure 5 This is a picture of the positive electrode sheet obtained in comparative example 1 being cut with a 500W continuous laser;

[0028] Figure 6 This is a picture of the positive electrode sheet obtained in comparative example 2 being cut with a 500W continuous laser;

[0029] Figure 7 This is a picture of the positive electrode sheet prepared in Example 3 being cut with a 500W continuous laser. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0032] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0033] Example 1

[0034] This embodiment provides a ceramic slurry, which includes the following raw materials in parts by weight: 50 parts of an organic solvent, 2 parts of a first binder, 8 parts of a photothermal conversion agent, 5 parts of a second binder and 35 parts of a ceramic powder; the organic solvent is N-methylpyrrolidone, the first binder is butyl acrylate; the second binder is polyvinylidene fluoride; the ceramic powder is boehmite powder, and its particle size is 400nm; the photothermal conversion agent is coal tar carbon dots.

[0035] The coal tar pitch carbon dots are obtained by the following steps:

[0036] (1) putting coal tar pitch solid into a ball mill jar, and then ball milling with a planetary ball mill to obtain coal tar pitch powder of smaller size;

[0037] (2) 1 g of coal tar powder was placed in a beaker, and then 500 g of a mixture of formic acid and hydrogen peroxide was added; the mixture of formic acid and hydrogen peroxide was prepared by mixing 88% formic acid and 30% hydrogen peroxide in a ratio of 2:1 by volume;

[0038] (3) reacting at room temperature under magnetic stirring at a speed of 400 rpm for 3 hours;

[0039] (4) removing large particles in the solution after the reaction by centrifugation at 10,000 rpm to obtain a suspension containing carbon dots;

[0040] (5) The suspension containing carbon dots is subjected to rotary evaporation at 60° C. to remove the reaction liquid, thereby obtaining coal tar pitch carbon dots.

[0041] The ceramic slurry preparation method specifically comprises the following steps:

[0042] S1: Add 20 kg of butyl acrylate to 500 kg of N-methylpyrrolidone, first stir at an orbital speed of 15 rpm / min for 10 min, then stir at an autogenous speed of 900 rpm / min for 30 min, and finally stir and disperse at both an orbital speed of 15 rpm / min and an autogenous speed of 900 rpm / min for 2 h to obtain a uniformly dispersed solution.

[0043] S2: 80 kg of coal tar pitch carbon dots were dried by baking at 45°C for 40 min and then added to the solution, and stirred and dispersed at a revolution speed of 15 rpm / min and a rotation speed of 900 rpm / min for 1 h to obtain the first colloid;

[0044] S3: adding 50 kg of polyvinylidene fluoride to the first colloid, stirring at a revolution speed of 45 rpm / min for 10 min, then stirring at a rotation speed of 1400 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 45 rpm / min and a rotation speed of 1400 rpm / min for 2 h to obtain a second colloid;

[0045] S4: adding 350 kg of boehmite powder to the second colloid, stirring at a revolution speed of 15 rpm / min for 10 min, then stirring at a rotation speed of 1600 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 15 rpm / min and a rotation speed of 1600 rpm / min for 1.5 h to obtain a slurry;

[0046] S5: The slurry was allowed to stand at 25° C. for 1.5 h to defoam, and then filtered through a 150-mesh filter to obtain a ceramic slurry.

[0047] This embodiment also provides a positive electrode sheet, referring to Figure 1 , first apply lithium iron phosphate positive electrode slurry on the positive electrode sheet 1, and the lithium iron phosphate positive electrode slurry is applied in the middle of the positive electrode sheet to form a material area 2, and then apply the ceramic slurry prepared in this embodiment on the pole ear 3 of the positive electrode sheet 1, the coating width of the ceramic slurry is smaller than the width of the pole ear 3, the width is 5mm, and the single-sided coating thickness is 25μm, forming a ceramic area 4, the edge spacing between the ceramic area 3 and the material area 2 is 0-0.5mm, and the spacing in this embodiment is 0.5mm, to obtain a positive electrode sheet.

[0048] Example 2

[0049] This embodiment provides a ceramic slurry, which includes the following raw materials by weight: 49.7 parts of organic solvent, 1.994 parts of first binder, 7.976 parts of photothermal conversion agent, 4.985 parts of second binder and 34.896 parts of ceramic powder; the organic solvent is N-methylpyrrolidone, the first binder is methyl acrylate; the second binder is sodium carboxymethyl cellulose; the ceramic powder is boehmite powder, and its particle size is 400nm; the photothermal conversion agent is coal tar pitch carbon dots. The preparation method of coal tar pitch carbon dots in this embodiment is the same as that in Example 1.

[0050] The ceramic slurry preparation method specifically comprises the following steps:

[0051] S1: Add 19.94 kg of butyl acrylate to 49.7 kg of N-methylpyrrolidone, first stir at an orbital speed of 15 rpm / min for 10 min, then stir at an autogenous speed of 900 rpm / min for 30 min, and finally stir and disperse at both an orbital speed of 15 rpm / min and an autogenous speed of 900 rpm / min for 2 h to obtain a uniformly dispersed solution.

[0052] S2: 79.76 kg of coal tar pitch carbon dots were dried by baking at 45°C for 40 min and then added to the solution, and stirred and dispersed at a revolution speed of 15 rpm / min and a rotation speed of 900 rpm / min for 1 h to obtain the first colloid;

[0053] S3: adding 49.85 kg of polyvinylidene fluoride to the first colloid, stirring at a revolution speed of 45 rpm / min for 10 min, then stirring at a rotation speed of 1400 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 45 rpm / min and a rotation speed of 1400 rpm / min for 2 h to obtain a second colloid;

[0054] S4: adding 348.96 kg of boehmite powder to the second colloid, stirring at a revolution speed of 15 rpm / min for 10 min, then stirring at a rotation speed of 1600 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 15 rpm / min and a rotation speed of 1600 rpm / min for 1.5 h to obtain a slurry;

[0055] S5: The slurry was allowed to stand at 27° C. for 2 h to defoam, and then filtered through a 150-mesh filter to obtain a ceramic slurry.

[0056] This embodiment also provides a positive electrode sheet, referring to Figure 2 , first apply lithium iron phosphate positive electrode slurry on the positive electrode sheet 1, and the lithium iron phosphate positive electrode slurry is applied in the middle of the positive electrode sheet to form a material area 2, and then apply the ceramic slurry prepared in this embodiment on the pole ear 3 of the positive electrode sheet 1, the coating width of the ceramic slurry is smaller than the width of the pole ear 3, the width is 5mm, and the single-sided coating thickness is 25μm, forming a ceramic area 4, the edge spacing between the ceramic area 3 and the material area 2 is 0-0.5mm, and the spacing in this embodiment is 0, and the positive electrode sheet is obtained.

[0057] Example 3

[0058] This embodiment provides a ceramic slurry, which includes the following raw materials by weight: 50.3 parts of organic solvent, 2.006 parts of first binder, 8.024 parts of photothermal conversion agent, 5.015 parts of second binder and 35.105 parts of ceramic powder; the organic solvent is N-methylpyrrolidone, the first binder is isooctyl acrylate; the second binder is sodium carboxymethyl cellulose; the ceramic powder is boehmite powder, and its particle size is 500nm; the photothermal conversion agent is coal tar pitch carbon dots. The preparation method of coal tar pitch carbon dots in this embodiment is the same as that in Example 1.

[0059] The ceramic slurry preparation method specifically comprises the following steps:

[0060] S1: Add 20.06 kg of butyl acrylate to 50.3 kg of N-methylpyrrolidone, first stir at an orbital speed of 15 rpm / min for 10 min, then stir at an autogenous speed of 900 rpm / min for 30 min, and finally stir and disperse at both an orbital speed of 15 rpm / min and an autogenous speed of 900 rpm / min for 2 h to obtain a uniformly dispersed solution.

[0061] S2: 80.24 kg of coal tar pitch carbon dots were dried by baking at 45°C for 40 min and then added to the solution, and stirred and dispersed at a revolution speed of 15 rpm / min and a rotation speed of 900 rpm / min for 1 h to obtain the first colloid;

[0062] S3: adding 50.15 kg of polyvinylidene fluoride to the first colloid, stirring at a revolution speed of 45 rpm / min for 10 min, then stirring at a rotation speed of 1400 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 45 rpm / min and a rotation speed of 1400 rpm / min for 2 h to obtain a second colloid;

[0063] S4: adding 351.05 kg of boehmite powder to the second colloid, stirring at a revolution speed of 15 rpm / min for 10 min, then stirring at a rotation speed of 1600 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 15 rpm / min and a rotation speed of 1600 rpm / min for 1.5 h to obtain a slurry;

[0064] S5: The slurry was allowed to stand at 30° C. for 1 h to defoam, and then filtered through a 150-mesh filter to obtain a ceramic slurry.

[0065] The present embodiment also provides a positive electrode sheet, wherein a lithium iron phosphate positive electrode slurry is first coated on the positive electrode sheet 1, and the lithium iron phosphate positive electrode slurry is coated in the middle of the positive electrode sheet to form a material area 2, and then the ceramic slurry prepared in the present embodiment is coated on the pole ear 3 of the positive electrode sheet 1, and the coating width of the ceramic slurry is smaller than the width of the pole ear 3, which is 5.2 mm, and the single-sided coating thickness is 25.2 μm to form a ceramic area 4, and the edge spacing between the ceramic area 3 and the material area 2 is 0-0.5 mm, and the spacing in the present embodiment is 0.3 mm to obtain a positive electrode sheet.

[0066] Example 4

[0067] This embodiment provides a ceramic slurry, which includes the following raw materials by weight: 50.1 parts of organic solvent, 2.004 parts of first binder, 8.016 parts of photothermal conversion agent, 5.01 parts of second binder and 35.07 parts of ceramic powder; the organic solvent is N-methylpyrrolidone, the first binder is isoethyl acrylate; the second binder is polyacrylic acid; the ceramic powder is boehmite powder with a particle size of 500nm; the photothermal conversion agent is coal tar pitch carbon dots. The preparation method of coal tar pitch carbon dots in this embodiment is the same as that in Example 1.

[0068] The ceramic slurry preparation method specifically comprises the following steps:

[0069] S1: Add 20.04 kg of butyl acrylate to 50.1 kg of N-methylpyrrolidone, first stir at an orbital speed of 15 rpm / min for 10 min, then stir at an autogenous speed of 900 rpm / min for 30 min, and finally stir and disperse at both an orbital speed of 15 rpm / min and an autogenous speed of 900 rpm / min for 2 h to obtain a uniformly dispersed solution.

[0070] S2: 80.16 kg of coal tar pitch carbon dots were dried by baking at 45°C for 40 min and then added to the solution, and stirred and dispersed at a revolution speed of 15 rpm / min and a rotation speed of 900 rpm / min for 1 h to obtain the first colloid;

[0071] S3: adding 50.1 kg of polyvinylidene fluoride to the first colloid, stirring at a revolution speed of 45 rpm / min for 10 min, then stirring at a rotation speed of 1400 rpm / min for 30 min, and finally stirring and dispersing at a revolution speed of 45 rpm / min and a rotation speed of 1400 rpm / min for 2 h to obtain a second colloid;

[0072] S4: adding 350.7 kg of boehmite powder to the second colloid, stirring at an orbital speed of 15 rpm / min for 10 min, then stirring at an autorotation speed of 1600 rpm / min for 30 min, and finally stirring and dispersing at both an orbital speed of 15 rpm / min and an autorotation speed of 1600 rpm / min for 1.5 h to obtain a slurry;

[0073] S5: The slurry was allowed to stand at 25° C. for 1.5 h to defoam, and then filtered through a 150-mesh filter to obtain a ceramic slurry.

[0074] The present embodiment also provides a positive electrode sheet, wherein a lithium iron phosphate positive electrode slurry is first coated on the positive electrode sheet 1, and the lithium iron phosphate positive electrode slurry is coated in the middle of the positive electrode sheet to form a material area 2, and then the ceramic slurry prepared in the present embodiment is coated on the pole ear 3 of the positive electrode sheet 1, and the coating width of the ceramic slurry is smaller than the width of the pole ear 3, which is 4.5 mm, and the single-sided coating thickness is 24.8 μm to form a ceramic area 4, and the edge spacing between the ceramic area 3 and the material area 2 is 0-0.5 mm, and the spacing in the present embodiment is 0.3 mm to obtain a positive electrode sheet.

[0075] Comparative Example 1

[0076] This comparative example provides a ceramic slurry. The difference between this comparative example and Example 1 is that: the photothermal conversion agent is insulating carbon black; and the ceramic slurry preparation method remains unchanged.

[0077] This comparative example provides a positive electrode sheet, and the positive electrode sheet is obtained in the same way as in Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides a ceramic slurry. The difference between this comparative example and Example 1 is that: the photothermal conversion agent is carbon nanotubes; and the ceramic slurry preparation method remains unchanged.

[0080] This comparative example provides a positive electrode sheet, and the positive electrode sheet is obtained in the same way as in Example 1.

[0081] Comparative Example 3

[0082] This comparative example provides a ceramic slurry. The difference between this comparative example and Example 1 is that: no photothermal conversion agent is added; and the ceramic slurry preparation method remains unchanged.

[0083] This comparative example provides a positive electrode sheet, and the positive electrode sheet is obtained in the same way as in Example 1.

[0084] Experimental example

[0085] Please refer to Figure 3 , Figure 3Spectral absorption diagram of ceramic slurries obtained in Example 1, Comparative Example 1 and Comparative Example 2. The spectral absorption capacity of the ceramic slurry obtained in Example 1 is greater than that of Comparative Example 1 and Comparative Example 2. The reason is that the semiconductor properties of coal tar carbon dots and their excellent photothermal properties make them highly sensitive to light and more easily absorb and convert light into thermal energy. Under a low-power laser, they can capture the laser to the maximum extent and convert it into a uniform hot spot, thereby cutting off the edge of the ceramic slurry and avoiding the associated phenomenon of the laser cutting process.

[0086] In order to better illustrate the excellent performance of the ceramic slurry of the present invention, the present invention uses different lasers and powers to verify the cutting effect of the positive electrode sheets made of the ceramic slurries of Examples 1-4 and the ceramic slurries of Comparative Examples 1-3. The results are as follows:

[0087] Table 1: Cutting effect of positive electrode sheet

[0088]

[0089]

[0090] According to Table 1, in Comparative Example 3, the positive electrode sheet was made from ceramic slurry without adding a photothermal conversion agent. Only a pulsed laser with a power of more than 800W can completely cut off the tab of the positive electrode sheet. However, the pulsed laser has high cost and short service life, and the actual application cost is relatively high. Figure 7 As shown, the positive electrode sheet of comparative example 3 cannot complete the cutting of the tab under the irradiation of a 500W continuous laser.

[0091] The photothermal conversion agents used in Comparative Examples 1-2 are insulating carbon black and carbon nanotubes, respectively. The ceramic slurry prepared is used to prepare the positive electrode sheet. The cutting effect is shown in Table 1. It can be seen that the positive electrode sheet of Comparative Examples 1 and 2 can only be cut with a continuous laser of more than 1000W or a pulsed laser. Figure 5 and Figure 6 It can be seen that the positive electrode sheet prepared in comparative example 1 exhibited a joint phenomenon when the tabs were cut under a 500W continuous laser, and the positive electrode sheet prepared in comparative example 2 also exhibited a joint phenomenon when the tabs were cut under a 500W continuous laser.

[0092] The positive electrode sheet prepared in Example 1-4 can complete the work of cutting the tab under a 500W continuous laser. Figure 4As shown, the positive electrode sheet prepared in Example 1 can complete the work of cutting the pole ear under a 500W continuous laser without any joint phenomenon. This is attributed to the semiconductor properties of coal tar pitch carbon dots and their excellent photothermal properties. Under the irradiation of low-power continuous laser, the laser absorption can be converted into thermal energy. The hydroxyl, carboxyl and other functional groups on the surface of the coal tar pitch carbon dots can keep the heat warm, so that the work of cutting the pole ear can be completed under a low-power continuous laser without any joint phenomenon, which reduces the cost and improves the yield.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ceramic slurry, characterized in that: The invention comprises the following raw materials in parts by weight: 49.7 to 50.3 parts of an organic solvent, 1.994 to 2.006 parts of a first binder, 7.976 to 8.024 parts of a photothermal conversion agent, 4.985 to 5.015 parts of a second binder and 34.896 to 35.105 parts of a ceramic powder; the photothermal conversion agent is coal tar pitch carbon dots.

2. The method for preparing ceramic slurry according to claim 1, characterized in that: The organic solvent, the first binder, the photothermal conversion agent, the second binder and the ceramic powder are mixed, dispersed and allowed to stand for defoaming by a wet slurry mixing method to obtain a ceramic slurry.

3. The method for preparing ceramic slurry according to claim 2, characterized in that: The photothermal conversion agent is coal tar pitch carbon dots, and the preparation method thereof is as follows: (1) ball milling the coal tar pitch solid to obtain a smaller-sized coal tar pitch powder; (2) adding coal tar powder to a mixture of formic acid and hydrogen peroxide to react; after the reaction, centrifuging to remove large particles in the solution after the reaction to obtain a suspension containing carbon dots; (3) The suspension containing carbon dots is subjected to rotary evaporation to remove the reaction liquid, thereby obtaining coal tar pitch carbon dots.

4. The method for preparing ceramic slurry according to claim 2, characterized in that: The ceramic powder is boehmite powder, and the particle size of the boehmite powder is 400-500 nm.

5. The method for preparing ceramic slurry according to claim 2, characterized in that: The first binder is one of methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate or hexyl methacrylate.

6. The method for preparing ceramic slurry according to claim 2, characterized in that: The second binder is one of polyvinylidene fluoride, sodium carboxymethyl cellulose or polyacrylic acid.

7. The method for preparing ceramic slurry according to claim 2, characterized in that: During the mixing and dispersing process, the revolution speed is 10-50 rpm / min, and the rotation speed is 800-1700 rpm / min.

8. The method for preparing ceramic slurry according to claim 2, characterized in that: The standing defoaming time is 1 to 2 hours, and the standing defoaming temperature is 25 to 30°C.

9. A positive electrode sheet, characterized in that: The ceramic slurry is prepared by the ceramic slurry of claim 1 or the ceramic slurry preparation method of claims 2 to 8, and the ceramic slurry is evenly coated on the tab of the positive electrode sheet to obtain the positive electrode sheet.

10. The positive electrode sheet according to claim 9, characterized in that: The coating width of the ceramic slurry is smaller than the width of the tab; the thickness of the ceramic slurry coated on one side is 25±2 μm.

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