Preparation method of conductive paste for lithium battery

Abstract

This invention discloses a method for preparing a conductive slurry for lithium batteries, specifically including the following steps: weighing the following raw materials in parts by weight: 20-30 parts of conductive agent, 1-3 parts of sodium dodecylbenzenesulfonate, 1-1.5 parts of carrageenan, and 80-100 parts of N,N-dimethylformamide; mixing the above raw materials evenly to obtain a conductive slurry; combining intermediate 7 with copper nitrate trihydrate to form a copper-based metal-organic framework, and then ultrasonically dispersing it with conductive ceramics, wherein the side chain amino groups can be grafted with the epoxy groups on the surface of the conductive ceramics, so that the mesh-like conductive particles are attached to the surface of the conductive ceramics to obtain a conductive agent. Compared with organic conductive agents, this conductive agent will not be corroded, nor will it oxidize like metal conductive agents, thus ensuring the service life of the battery and not significantly affecting the battery capacity.

Description

Technical Field

[0001] This invention relates to the field of lithium battery manufacturing technology, and specifically to a method for preparing a conductive paste for lithium batteries. Background Technology

[0002] Lithium-ion batteries, as an emerging energy storage medium, are attracting significant attention due to their green, pollution-free, and recyclable properties. The manufacturing process of lithium-ion batteries is highly rigorous, typically involving the following steps: slurry preparation, coating, drying, rolling, slitting, and assembly. In the lithium-ion battery manufacturing process, the quality of the initial battery slurry directly impacts the performance of the subsequently manufactured battery. Lithium-ion battery slurry is prepared by uniformly dispersing active materials, binders, and conductive agents in a solvent through stirring. To achieve superior electrochemical performance, the battery industry demands higher particle sizes for electrode slurries, with a trend towards nanoscale applications.

[0003] Currently, graphene is used as a conductive agent in lithium-ion battery conductive pastes. Graphene has attracted widespread attention due to its excellent electrochemical and mechanical properties. However, the sheet-like structure of graphene inhibits lithium-ion diffusion, easily causing severe polarization in lithium-ion batteries and reducing their capacity. The abundant functional groups on the graphene surface are like tiny wounds; adding too many not only reduces the battery's energy density but also increases electrolyte absorption. Furthermore, it can increase side reactions with the electrolyte, affecting cycle life and potentially even leading to safety issues. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing conductive slurry for lithium batteries, which solves the problem that the capacity of lithium batteries will decrease significantly after multiple charge and discharge cycles.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a conductive paste for lithium batteries specifically includes the following steps:

[0007] Weigh the following raw materials in parts by weight: 20-30 parts conductive agent, 1-3 parts sodium dodecylbenzenesulfonate, 1-1.5 parts carrageenan, and 80-100 parts N,N-dimethylformamide. Mix the above raw materials evenly to obtain a conductive paste.

[0008] Furthermore, the conductive agent is prepared by the following steps:

[0009] Step A1: Dissolve pyromellitic dianhydride in N,N-dimethylformamide, add iodine, stir and add liquid bromine dropwise at a speed of 150-200 r / min and a temperature of 60-70℃, react for 2-3 h, add sodium hydroxide and mix well, wash with water, distill, recrystallize N,N-dimethylformamide to obtain intermediate 1; mix 2-amino-p-cresol, concentrated hydrochloric acid and deionized water well, stir and add sodium acetate solution and acetic anhydride at a speed of 200-300 r / min and a temperature of 50-60℃, react for 5-7 h to obtain intermediate 2;

[0010] The reaction process is as follows:

[0011]

[0012] Step A2: Mix intermediate 1, intermediate 2, potassium carbonate, and tetrahydrofuran evenly, and react for 3-5 hours at a speed of 200-300 r / min and a temperature of 40-50℃ to obtain intermediate 3. Mix intermediate 3, N-bromosuccinimide, benzoyl peroxide, and carbon tetrachloride evenly, and react for 10-15 hours at a speed of 200-300 r / min and a temperature of 50-60℃ to obtain intermediate 4. Mix intermediate 4, iminooxalic acid, sodium hydroxide, and N,N-dimethylformamide evenly, and react for 3-5 hours at a speed of 200-300 r / min and a temperature of 20-25℃. Raise the temperature to 100-110℃ and continue the reaction for 10-15 hours. Adjust the pH of the reaction solution to 2-3 to obtain intermediate 5.

[0013] The reaction process is as follows:

[0014]

[0015] Step A3: Mix intermediate 5, melamine, and N,N-dimethylformamide evenly, purge with nitrogen for protection, and react for 10-15 hours at a speed of 150-200 r / min and a temperature of 120-130℃. Pour the reaction solution into diethyl ether, filter to remove the filtrate, and obtain intermediate 6. Mix intermediate 6 and hydrochloric acid solution evenly, and reflux at a temperature of 100-110℃ for 30-40 minutes. Adjust the pH of the reaction solution to neutral to obtain intermediate 7.

[0016] Step A4: Mix intermediate 7, copper nitrate trihydrate, deionized water, and N,N-dimethylformamide evenly. React at 200-300 r / min and 80-90℃ for 20-25 h. Filter to remove the filtrate to obtain conductive particles. Mix the conductive particles, conductive ceramic, and tetrahydrofuran evenly. Sonicate at 40-50 kHz, 40-50℃, and pH 10-11 for 2-3 h. Filter and dry to obtain the conductive agent.

[0017] Furthermore, in step A1, the mass ratio of pyromellitic dianhydride, iodine, liquid bromine, and sodium hydroxide is 10:0.5:12:20, and the volume ratio of 2-amino-p-cresol, concentrated hydrochloric acid, deionized water, sodium acetate solution, and acetic anhydride is 3.5g:90mL:3.8mL:15mL:4.2mL. The mass fraction of concentrated hydrochloric acid is 36%, and the mass fraction of sodium acetate solution is 60%.

[0018] Furthermore, in step A2, the molar ratio of intermediate 1, intermediate 2, and potassium carbonate is 1:2:2, the molar ratio of intermediate 3 and N-bromosuccinimide is 1:1.1, and the molar ratio of intermediate 4, iminooxalic acid, and sodium hydroxide is 1:2:2.

[0019] Furthermore, the molar ratio of intermediate 5 and melamine in step A3 is 6:1, the volume ratio of intermediate 6 to hydrochloric acid solution is 1g:5mL, and the mass fraction of hydrochloric acid solution is 18%.

[0020] Furthermore, the molar ratio of intermediate 7 and copper nitrate trihydrate mentioned in step A4 is 1:4.3, and the mass ratio of conductive particles and conductive ceramics is 3:1.

[0021] Furthermore, the conductive ceramic is made by the following steps:

[0022] Step B1: Place silicon carbide, zinc oxide, and aluminum oxide in an oven and heat-treat at 120-130℃ for 2-3 hours. Then, add them to a zirconia ball mill jar and ball mill them for 6-8 hours with water as the medium at a speed of 300-400 r / min to obtain a mixture. Dry the mixture and add it to a muffle furnace. Heat the temperature to 450-500℃ at a heating rate of 3℃ / min and heat-treat for 2-4 hours to obtain a pretreated composite material.

[0023] Step B2: Add polyvinyl alcohol to the pretreated composite material, ball mill for 30-40 min, press into shape in a mold, let stand for 20-25 h, then crush and granulate, place in a muffle furnace, raise the temperature to 500-550℃ at a heating rate of 1℃ / min, hold under nitrogen atmosphere for 5-7 h, continue to raise the temperature to 1100-1200℃, hold for 2-3 h, and obtain ceramic particles;

[0024] Step B3: Disperse ceramic particles in deionized water, add ethanol and KH560 at a speed of 120-150 r / min and a temperature of 60-70℃, adjust the pH of the reaction solution to be alkaline, and react for 3-5 hours. After filtration to remove the filtrate, dry the substrate to obtain conductive ceramics.

[0025] Furthermore, the mass ratio of silicon carbide, zinc oxide, and aluminum oxide in step B1 is 5-8:50:3-5.

[0026] Furthermore, the amount of the pretreated composite material used in step B2 is 5-10% of the mass of polyvinyl alcohol.

[0027] Furthermore, the amount of KH560 used in step B3 is 3-5% of the mass of the ceramic particles.

[0028] The beneficial effects of this invention are as follows: In the process of preparing a conductive slurry for lithium batteries, this invention prepares a conductive agent. This conductive agent is prepared by treating polyphenylene dianhydride with liquid bromine to obtain intermediate 1. 2-Amino-p-cresol is then amino-protected to obtain intermediate 2. Intermediate 1 and intermediate 2 are reacted to obtain intermediate 3. Intermediate 3 is treated with N-bromosuccinimide to obtain intermediate 4. Intermediate 4 is reacted with iminooxalic acid to obtain intermediate 5. Intermediate 5 is reacted with melamine to form an imide, which then forms a molecular network structure to obtain intermediate 6. The imide is then deprotected with hydrochloric acid solution to obtain intermediate 7. Intermediate 7 is combined with copper nitrate trihydrate to form a copper-based metal-organic framework, which is then combined with conductive ceramic superconducting polymers. The conductive agent is produced by sintering silicon carbide, zinc oxide, and aluminum oxide under nitrogen atmosphere to obtain ceramic particles. The particles are then surface-treated to graft epoxy groups onto the surface of the conductive ceramic. Nitrogen is used as a dopant source, which enhances the conductivity of the conductive ceramic. The copper-based metal-organic framework on the surface has a large specific surface area, ensuring normal lithium-ion diffusion. Unlike organic conductive agents, it is not corroded, nor does it oxidize like metal conductive agents, thus ensuring battery life and not significantly affecting battery capacity. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing a conductive paste for lithium batteries specifically includes the following steps:

[0032] Weigh the following raw materials in parts by weight: 20 parts conductive agent, 1 part sodium dodecylbenzenesulfonate, 1 part carrageenan, and 80 parts N,N-dimethylformamide. Mix the above raw materials evenly to prepare a conductive paste.

[0033] The conductive agent is prepared by the following steps:

[0034] Step A1: Dissolve pyromellitic dianhydride in N,N-dimethylformamide, add iodine, stir and add liquid bromine dropwise at 150 r / min and 60℃, react for 2 h, add sodium hydroxide and mix well, wash with water, distill, recrystallize N,N-dimethylformamide to obtain intermediate 1; mix 2-amino-p-cresol, concentrated hydrochloric acid and deionized water well, stir and add sodium acetate solution and acetic anhydride at 200 r / min and 50℃, react for 5 h to obtain intermediate 2;

[0035] Step A2: Intermediate 1, Intermediate 2, potassium carbonate, and tetrahydrofuran are mixed evenly and reacted at 200 r / min and 40°C for 3 h to obtain Intermediate 3. Intermediate 3, N-bromosuccinimide, benzoyl peroxide, and carbon tetrachloride are mixed evenly and reacted at 200 r / min and 50°C for 10 h to obtain Intermediate 4. Intermediate 4, iminooxalic acid, sodium hydroxide, and N,N-dimethylformamide are mixed evenly and reacted at 200 r / min and 20°C for 3 h. The temperature is then raised to 100°C and the reaction continues for 10 h. The pH of the reaction solution is adjusted to 2 to obtain Intermediate 5.

[0036] Step A3: Mix intermediate 5, melamine, and N,N-dimethylformamide evenly, purge with nitrogen for protection, and react for 10 hours at a speed of 150 r / min and a temperature of 120℃. Pour the reaction solution into diethyl ether, filter to remove the filtrate, and obtain intermediate 6. Mix intermediate 6 and hydrochloric acid solution evenly, and reflux at a temperature of 100℃ for 30 minutes. Adjust the pH of the reaction solution to neutral to obtain intermediate 7.

[0037] Step A4: Mix intermediate 7, copper nitrate trihydrate, deionized water, and N,N-dimethylformamide evenly. React at 200 r / min and 80°C for 20 h. Filter to remove the filtrate to obtain conductive particles. Mix the conductive particles, conductive ceramic, and tetrahydrofuran evenly. Sonicate at 40 kHz, 40°C, and pH 10 for 2 h. Filter and dry to obtain the conductive agent.

[0038] In step A1, the mass ratio of pyromellitic dianhydride, iodine, liquid bromine, and sodium hydroxide is 10:0.5:12:20. The volume ratio of 2-amino-p-cresol, concentrated hydrochloric acid, deionized water, sodium acetate solution, and acetic anhydride is 3.5g:90mL:3.8mL:15mL:4.2mL. The mass fraction of concentrated hydrochloric acid is 36%, and the mass fraction of sodium acetate solution is 60%.

[0039] The molar ratio of intermediate 1, intermediate 2, and potassium carbonate in step A2 is 1:2:2; the molar ratio of intermediate 3 and N-bromosuccinimide is 1:1.1; and the molar ratio of intermediate 4, iminooxalic acid, and sodium hydroxide is 1:2:2.

[0040] The molar ratio of intermediate 5 and melamine in step A3 is 6:1, the volume ratio of intermediate 6 to hydrochloric acid solution is 1g:5mL, and the mass fraction of hydrochloric acid solution is 18%.

[0041] The molar ratio of intermediate 7 and copper nitrate trihydrate mentioned in step A4 is 1:4.3, and the mass ratio of conductive particles and conductive ceramics is 3:1.

[0042] The conductive ceramic is made by the following steps:

[0043] Step B1: Place silicon carbide, zinc oxide, and aluminum oxide in an oven and heat-treat at 120℃ for 2 hours. Then, add them to a zirconia ball mill jar and ball mill them for 6 hours with water as the medium at a speed of 300 r / min to obtain a mixture. Dry the mixture and add it to a muffle furnace. Heat the temperature to 450℃ at a heating rate of 3℃ / min and heat-treat for 2 hours to obtain a pretreated composite material.

[0044] Step B2: Add polyvinyl alcohol to the pretreated composite material, ball mill for 30 min, press into shape in a mold, let stand for 20 h, then crush and granulate, place in a muffle furnace, raise the temperature to 500℃ at a heating rate of 1℃ / min, hold in a nitrogen atmosphere for 5 h, continue to raise the temperature to 1100℃, hold for 2 h, and obtain ceramic particles.

[0045] Step B3: Disperse ceramic particles in deionized water, add ethanol and KH560 at a speed of 120 r / min and a temperature of 60℃, adjust the pH of the reaction solution to be alkaline, react for 3 hours, filter to remove the filtrate, dry the substrate, and obtain conductive ceramic.

[0046] The mass ratio of silicon carbide, zinc oxide, and aluminum oxide in step B1 is 5:50:3.

[0047] The amount of the pretreated composite material used in step B2 is 5% of the mass of polyvinyl alcohol.

[0048] The amount of KH560 used in step B3 is 3% of the mass of the ceramic particles.

[0049] Example 2

[0050] A method for preparing a conductive paste for lithium batteries specifically includes the following steps:

[0051] Weigh the following raw materials in parts by weight: 25 parts conductive agent, 2 parts sodium dodecylbenzenesulfonate, 1.3 parts carrageenan, and 90 parts N,N-dimethylformamide. Mix the above raw materials evenly to obtain a conductive paste.

[0052] The conductive agent is prepared by the following steps:

[0053] Step A1: Dissolve pyromellitic dianhydride in N,N-dimethylformamide, add iodine, stir and add liquid bromine dropwise at 180 r / min and 65℃, react for 2.5 h, add sodium hydroxide and mix well, wash with water, distill, recrystallize N,N-dimethylformamide to obtain intermediate 1; mix 2-amino-p-cresol, concentrated hydrochloric acid and deionized water well, stir and add sodium acetate solution and acetic anhydride at 200 r / min and 55℃, react for 6 h to obtain intermediate 2;

[0054] Step A2: Intermediate 1, Intermediate 2, potassium carbonate, and tetrahydrofuran are mixed evenly and reacted at 300 r / min and 45°C for 4 h to obtain Intermediate 3. Intermediate 3, N-bromosuccinimide, benzoyl peroxide, and carbon tetrachloride are mixed evenly and reacted at 200 r / min and 55°C for 13 h to obtain Intermediate 4. Intermediate 4, iminooxalic acid, sodium hydroxide, and N,N-dimethylformamide are mixed evenly and reacted at 200 r / min and 23°C for 4 h. The temperature is then raised to 105°C and the reaction continues for 13 h. The pH of the reaction solution is adjusted to 2 to obtain Intermediate 5.

[0055] Step A3: Mix intermediate 5, melamine, and N,N-dimethylformamide evenly, purge with nitrogen for protection, and react for 13 hours at a speed of 180 r / min and a temperature of 125℃. Pour the reaction solution into diethyl ether, filter to remove the filtrate, and obtain intermediate 6. Mix intermediate 6 and hydrochloric acid solution evenly, and reflux at a temperature of 105℃ for 35 minutes. Adjust the pH of the reaction solution to neutral to obtain intermediate 7.

[0056] Step A4: Mix intermediate 7, copper nitrate trihydrate, deionized water, and N,N-dimethylformamide evenly. React at 200 r / min and 85°C for 23 h. Filter to remove the filtrate to obtain conductive particles. Mix the conductive particles, conductive ceramic, and tetrahydrofuran evenly. Sonicate at 45 kHz, 45°C, and pH 10 for 2 h. Filter and dry to obtain the conductive agent.

[0057] In step A1, the mass ratio of pyromellitic dianhydride, iodine, liquid bromine, and sodium hydroxide is 10:0.5:12:20. The volume ratio of 2-amino-p-cresol, concentrated hydrochloric acid, deionized water, sodium acetate solution, and acetic anhydride is 3.5g:90mL:3.8mL:15mL:4.2mL. The mass fraction of concentrated hydrochloric acid is 36%, and the mass fraction of sodium acetate solution is 60%.

[0058] The molar ratio of intermediate 1, intermediate 2, and potassium carbonate in step A2 is 1:2:2; the molar ratio of intermediate 3 and N-bromosuccinimide is 1:1.1; and the molar ratio of intermediate 4, iminooxalic acid, and sodium hydroxide is 1:2:2.

[0059] The molar ratio of intermediate 5 and melamine in step A3 is 6:1, the volume ratio of intermediate 6 to hydrochloric acid solution is 1g:5mL, and the mass fraction of hydrochloric acid solution is 18%.

[0060] The molar ratio of intermediate 7 and copper nitrate trihydrate mentioned in step A4 is 1:4.3, and the mass ratio of conductive particles and conductive ceramics is 3:1.

[0061] The conductive ceramic is made by the following steps:

[0062] Step B1: Place silicon carbide, zinc oxide, and aluminum oxide in an oven and heat-treat at 125℃ for 2.5 hours. Then, add them to a zirconia ball mill jar and ball mill them for 7 hours using water as the medium at a speed of 300 r / min to obtain a mixture. Dry the mixture and add it to a muffle furnace. Heat the temperature to 480℃ at a heating rate of 3℃ / min and heat-treat for 3 hours to obtain a pretreated composite material.

[0063] Step B2: Add polyvinyl alcohol to the pretreated composite material, ball mill for 35 min, press into shape in a mold, let stand for 23 h, then crush and granulate, place in a muffle furnace, raise the temperature to 530°C at a heating rate of 1°C / min, hold in a nitrogen atmosphere for 6 h, continue to raise the temperature to 1150°C, hold for 2 h, and obtain ceramic particles;

[0064] Step B3: Disperse ceramic particles in deionized water, add ethanol and KH560 at a speed of 150 r / min and a temperature of 65℃, adjust the pH of the reaction solution to be alkaline, react for 4 h, filter to remove the filtrate, dry the substrate, and obtain conductive ceramic.

[0065] The mass ratio of silicon carbide, zinc oxide, and aluminum oxide in step B1 is 7:50:4.

[0066] The amount of the pretreated composite material used in step B2 is 8% of the mass of polyvinyl alcohol.

[0067] The amount of KH560 used in step B3 is 4% of the mass of the ceramic particles.

[0068] Example 3

[0069] A method for preparing a conductive paste for lithium batteries specifically includes the following steps:

[0070] Weigh the following raw materials in parts by weight: 30 parts conductive agent, 3 parts sodium dodecylbenzenesulfonate, 1.5 parts carrageenan, and 100 parts N,N-dimethylformamide. Mix the above raw materials evenly to obtain a conductive paste.

[0071] The conductive agent is prepared by the following steps:

[0072] Step A1: Dissolve pyromellitic dianhydride in N,N-dimethylformamide, add iodine, stir and add liquid bromine dropwise at 200 r / min and 70℃, react for 3 h, add sodium hydroxide and mix well, wash with water, distill, recrystallize N,N-dimethylformamide to obtain intermediate 1; mix 2-amino-p-cresol, concentrated hydrochloric acid and deionized water well, stir and add sodium acetate solution and acetic anhydride at 300 r / min and 60℃, react for 7 h to obtain intermediate 2;

[0073] Step A2: Intermediate 1, Intermediate 2, potassium carbonate, and tetrahydrofuran are mixed evenly and reacted at 300 r / min and 50°C for 5 h to obtain Intermediate 3. Intermediate 3, N-bromosuccinimide, benzoyl peroxide, and carbon tetrachloride are mixed evenly and reacted at 300 r / min and 60°C for 15 h to obtain Intermediate 4. Intermediate 4, iminooxalic acid, sodium hydroxide, and N,N-dimethylformamide are mixed evenly and reacted at 300 r / min and 25°C for 5 h. The temperature is then raised to 110°C and the reaction continues for 15 h. The pH of the reaction solution is adjusted to 3 to obtain Intermediate 5.

[0074] Step A3: Mix intermediate 5, melamine, and N,N-dimethylformamide evenly, purge with nitrogen for protection, and react for 15 hours at a speed of 200 r / min and a temperature of 130℃. Pour the reaction solution into diethyl ether, filter to remove the filtrate, and obtain intermediate 6. Mix intermediate 6 and hydrochloric acid solution evenly, and reflux at a temperature of 110℃ for 40 minutes. Adjust the pH of the reaction solution to neutral to obtain intermediate 7.

[0075] Step A4: Mix intermediate 7, copper nitrate trihydrate, deionized water, and N,N-dimethylformamide evenly. React at 300 r / min and 90°C for 25 h. Filter to remove the filtrate to obtain conductive particles. Mix the conductive particles, conductive ceramic, and tetrahydrofuran evenly. Sonicate at 50 kHz, 50°C, and pH 11 for 3 h. Filter and dry to obtain the conductive agent.

[0076] In step A1, the mass ratio of pyromellitic dianhydride, iodine, liquid bromine, and sodium hydroxide is 10:0.5:12:20. The volume ratio of 2-amino-p-cresol, concentrated hydrochloric acid, deionized water, sodium acetate solution, and acetic anhydride is 3.5g:90mL:3.8mL:15mL:4.2mL. The mass fraction of concentrated hydrochloric acid is 36%, and the mass fraction of sodium acetate solution is 60%.

[0077] The molar ratio of intermediate 1, intermediate 2, and potassium carbonate in step A2 is 1:2:2; the molar ratio of intermediate 3 and N-bromosuccinimide is 1:1.1; and the molar ratio of intermediate 4, iminooxalic acid, and sodium hydroxide is 1:2:2.

[0078] The molar ratio of intermediate 5 and melamine in step A3 is 6:1, the volume ratio of intermediate 6 to hydrochloric acid solution is 1g:5mL, and the mass fraction of hydrochloric acid solution is 18%.

[0079] The molar ratio of intermediate 7 and copper nitrate trihydrate mentioned in step A4 is 1:4.3, and the mass ratio of conductive particles and conductive ceramics is 3:1.

[0080] The conductive ceramic is made by the following steps:

[0081] Step B1: Place silicon carbide, zinc oxide, and aluminum oxide in an oven and heat-treat at 130℃ for 3 hours. Then, add them to a zirconia ball mill jar and ball mill them for 8 hours at 400 r / min using water as the medium to obtain a mixture. Dry the mixture and add it to a muffle furnace. Heat the temperature to 500℃ at a heating rate of 3℃ / min and heat-treat for 4 hours to obtain a pretreated composite material.

[0082] Step B2: Add polyvinyl alcohol to the pretreated composite material, ball mill for 40 min, press into shape in a mold, let stand for 25 h, then crush and granulate, place in a muffle furnace, raise the temperature to 550℃ at a heating rate of 1℃ / min, hold in nitrogen atmosphere for 7 h, continue to raise the temperature to 1200℃, hold for 3 h, and obtain ceramic particles;

[0083] Step B3: Disperse ceramic particles in deionized water, add ethanol and KH560 at a speed of 150 r / min and a temperature of 70℃, adjust the pH of the reaction solution to be alkaline, react for 5 h, filter to remove the filtrate, dry the substrate, and obtain conductive ceramic.

[0084] The mass ratio of silicon carbide, zinc oxide, and aluminum oxide in step B1 is 8:50:5.

[0085] The amount of the pretreated composite material used in step B2 is 10% of the mass of polyvinyl alcohol.

[0086] The amount of KH560 used in step B3 is 5% of the mass of the ceramic particles.

[0087] Comparative Example 1

[0088] This comparative example uses graphene instead of a conductive agent compared to Example 1, but the other steps are the same.

[0089] Comparative Example 2

[0090] This comparative example uses conductive paste prepared by Chinese patent CN109671952A.

[0091] Comparative Example 3

[0092] This comparative example uses conductive paste prepared by Chinese patent CN112072103A.

[0093] The conductive slurries prepared in Examples 1-3 and Comparative Examples 1-3 were used to make lithium batteries. The amount of conductive slurry added was 1% of the mass of the positive electrode of the battery. The capacity retention rate and the initial specific capacity were tested after 100 cycles at 1C and 5C. The charging cutoff voltage was 4.2V. The results are shown in the table below.

[0094]

[0095] As shown in the table above, the conductive slurry for lithium batteries prepared in Examples 1-3 retains a capacity of 99.62-99.88% after 100 cycles at 1C and 99.23-99.58% after 100 cycles at 5C. Its soluble content is 532.182-546.523 mAh / g, indicating that the present invention has a good specific capacity and the battery capacity does not decrease significantly after multiple charge and discharge cycles.

[0096] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing an electrically conductive paste for lithium batteries, characterized by: Specifically, the steps include the following: Weigh the following raw materials in parts by weight: 20-30 parts conductive agent, 1-3 parts sodium dodecylbenzenesulfonate, 1-1.5 parts carrageenan, and 80-100 parts N,N-dimethylformamide. Mix the above raw materials evenly to prepare a conductive paste. The conductive agent is prepared by the following steps: Step A1: Dissolve pyromellitic dianhydride in N,N-dimethylformamide, add iodine, stir and add liquid bromine dropwise, and after the reaction, add sodium hydroxide and mix evenly. Wash with water, distill, and recrystallize N,N-dimethylformamide to obtain intermediate 1. Mix 2-amino-p-cresol, concentrated hydrochloric acid, and deionized water, stir and add sodium acetate solution and acetic anhydride, and react to obtain intermediate 2. Step A2: Intermediate 1, intermediate 2, potassium carbonate, and tetrahydrofuran are mixed and reacted to obtain intermediate 3. Intermediate 3, N-bromosuccinimide, benzoyl peroxide, and carbon tetrachloride are mixed and reacted to obtain intermediate 4. Intermediate 4, iminooxalic acid, sodium hydroxide, and N,N-dimethylformamide are mixed and reacted, and the reaction is continued by raising the temperature. The pH value of the reaction solution is adjusted to obtain intermediate 5. Step A3: After mixing and reacting intermediate 5, melamine and N,N-dimethylformamide, the reaction solution is poured into diethyl ether, filtered to remove the filtrate, and intermediate 6 is obtained. Intermediate 6 is mixed with hydrochloric acid solution and refluxed, and the pH of the reaction solution is adjusted to neutral to obtain intermediate 7. Step A4: After mixing and reacting intermediate 7, copper nitrate trihydrate, deionized water, and N,N-dimethylformamide, filter to remove the filtrate to obtain conductive particles. Mix the conductive particles, conductive ceramics, and tetrahydrofuran and sonicate them at a temperature of 40-50℃ and a pH of 10-11. Filter and dry to obtain a conductive agent. The conductive ceramic is made by the following steps: Step B1: Place silicon carbide, zinc oxide, and aluminum oxide in an oven, keep them warm, then add them to a zirconia ball mill jar and ball mill them with water as the medium to obtain a mixture. Dry the mixture, add it to a muffle furnace, keep it warm, and obtain a pretreated composite material. Step B2: Add polyvinyl alcohol to the pretreated composite material, ball mill it, press it into shape in a mold, place it, crush and granulate it, place it in a muffle furnace, raise the temperature to 500-550℃, keep it in a nitrogen environment, and then continue to raise the temperature to 1000-1200℃ to obtain ceramic particles. Step B3: Disperse ceramic particles in deionized water, add ethanol and KH560, adjust the pH of the reaction solution to alkaline, carry out the reaction, filter to remove the filtrate, dry the substrate, and obtain conductive ceramics; The mass ratio of silicon carbide, zinc oxide, and aluminum oxide in step B1 is 5-8:50:3-5; The amount of the pretreated composite material used in step B2 is 5-10% of the mass of polyvinyl alcohol.

2. The method of claim 1, wherein the conductive paste for a lithium battery is prepared by adding the conductive material to the solvent and then adding the binder and the dispersant to the conductive material. The mass ratio of pyromellitic dianhydride, iodine, liquid bromine, and sodium hydroxide in step A1 is 10:0.5:12:

20. The volume ratio of 2-amino-p-cresol, concentrated hydrochloric acid, deionized water, sodium acetate solution, and acetic anhydride is 3.5g:90mL:3.8mL:15mL:4.2mL. The mass fraction of concentrated hydrochloric acid is 36%, and the mass fraction of sodium acetate solution is 60%.

3. The method of claim 1, wherein the conductive paste for a lithium battery is prepared by adding 0.1 to 5 parts by weight of the carbon black to 100 parts by weight of the binder. The molar ratio of intermediate 1, intermediate 2, and potassium carbonate in step A2 is 1:2:2; the molar ratio of intermediate 3 and N-bromosuccinimide is 1:1.1; and the molar ratio of intermediate 4, iminooxalic acid, and sodium hydroxide is 1:2:

2.

4. The method for preparing a conductive paste for lithium batteries according to claim 1, characterized in that: The molar ratio of intermediate 5 to melamine in step A3 is 6:1, the volume ratio of intermediate 6 to hydrochloric acid solution is 1g:5mL, and the mass fraction of hydrochloric acid solution is 18%.

5. The method for preparing a conductive paste for lithium batteries according to claim 1, characterized in that: The molar ratio of intermediate 7 and copper nitrate trihydrate mentioned in step A4 is 1:4.3, and the mass ratio of conductive particles and conductive ceramics is 3:

1.

6. The method for preparing a conductive paste for lithium batteries according to claim 1, characterized in that: The amount of KH560 used in step B3 is 3-5% of the mass of the ceramic particles.

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