A high solid conductive paste and a preparation method thereof

Abstract

The application discloses a kind of high solid content conductive paste, including conductive agent, thickening agent and solvent, thickening agent is polymerized by monomer A and monomer B.It also discloses the preparation method of the high solid content conductive paste.The conductive paste prepared by the application introduces ionic liquid structure and sulfonic acid group, which can reduce the impedance of electrode sheet, improve the ion conductivity of electrode sheet, enhance the rate performance of battery, increase the adhesion of electrode sheet, while reducing the amount of adhesive, improve the proportion of active material, further increase the energy density of battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, specifically to a high-solids-content conductive slurry and its preparation method. Background Technology

[0002] The main function of conductive agents in lithium-ion battery electrodes is to form a conductive network structure and improve the conductivity of the electrodes. Therefore, as a crucial component of lithium-ion batteries, conductive agents significantly influence their performance. However, currently, to ensure effective dispersion of the conductive agent in the slurry, manufacturers prepare conductive slurries with low solid content, which is detrimental to electrode processing. Conversely, increasing the solid content leads to severe agglomeration of the conductive agent and unsatisfactory dispersion, especially with mid-to-high-end conductive agent slurries. Poor dispersion can result in suboptimal electrical performance even with highly conductive agents in lithium-ion battery applications. Therefore, there is a need to develop a conductive slurry with higher solid content to meet current requirements. Summary of the Invention

[0003] In view of this, the purpose of this invention is to address the shortcomings of the prior art by providing a high-solids-content conductive slurry with good dispersibility, and also to provide a method for preparing the conductive slurry.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A high-solids-content conductive paste includes a conductive agent, a thickener, and a solvent, wherein the thickener is polymerized from monomer A and monomer B, and the structural formula of monomer A is one or more of formulas I, II, and III;

[0006]

[0007]

[0008] R, R1, and R2 are selected from -CH=CH2 and -C(CH3=CH2);

[0009] The structural formula of the monomer B is shown in Formula IV;

[0010]

[0011] Preferably, the conductive agent is one or more of graphene, carbon nanotubes, conductive carbon fibers, conductive carbon black, and conductive graphite.

[0012] Preferably, the mass ratio of the conductive agent, thickener, and solvent is 1–10: 1–5: 84–97.

[0013] Preferably, the mass ratio of monomer A to monomer B is 1 to 4:1.

[0014] A method for preparing a high-solids-content conductive paste includes the following steps:

[0015] S1: Add the conductive agent to a mixture of deionized water and ethanol to prepare a conductive suspension. Then, add the conductive suspension to a high-pressure homogenizer and set the pressure and running time. Then, transfer it to a stirring container, add monomer A, stir for 1 to 3 hours, and dry to obtain the modified conductive agent.

[0016] S2: Add the modified conductive agent prepared by monomers B and S1 to the solvent, stir thoroughly, then raise the temperature to 50-80℃, add azobisisobutyronitrile initiator, and continue stirring for 1-10 hours to obtain the conductive slurry.

[0017] Preferably, the operating pressure of the high-pressure homogenizer in step S1 is 50-200 MPa.

[0018] Preferably, the running time of the high-pressure homogenizer in step S1 is 30 to 120 minutes.

[0019] The beneficial effects of this invention are:

[0020] The conductive agent of this invention is fully dispersed under the high pressure of a high-pressure homogenizer, and further bonded to the conductive agent by monomer A through non-covalent bonds, preventing secondary agglomeration of the conductive agent and improving the dispersibility of the conductive slurry.

[0021] Monomer A and monomer B undergo in-situ free radical polymerization under the action of an initiator to form a thickener, which prevents the conductive agent from settling, further improves the dispersibility and stability of the conductive agent, and can also increase the solid content of the conductive slurry and its compatibility with the polymer, further improving the processing performance of the electrode.

[0022] The conductive paste of this invention incorporates an ionic liquid structure and sulfonic acid groups, which can reduce the impedance of the electrode sheet, increase the conductivity of the electrode sheet ions, improve the rate performance of the battery, increase the adhesion of the electrode sheet, reduce the amount of adhesive, increase the proportion of active material, and further increase the energy density of the battery. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments.

[0024] Example 1:

[0025] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0026] The structural formula of monomer A is R is -CH=CH2.

[0027] The structural formula of monomer B is shown below:

[0028]

[0029] The method for preparing this conductive paste includes the following steps:

[0030] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Add the suspension to a high-pressure homogenizer and run it at a pressure of 100MPa for 90min. Then transfer it to a stirring container, add 2g of monomer A, stir for 2h, and dry to obtain the modified conductive agent.

[0031] S2: Add 1g of monomer B and 6g of the modified conductive agent prepared by S1 to 93mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0032] Example 2:

[0033] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0034] The structural formula of monomer A is R is -CH=CH2; monomer B is the same as in Example 1.

[0035] The method for preparing this conductive paste includes the following steps:

[0036] S1: Add 1g of carbon nanotubes and 1g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Then add it to a high-pressure homogenizer and run it at a pressure of 50MPa for 120min. Then transfer it to a stirring container and add 3g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0037] S2: Add 1g of monomer B and 3g of the modified conductive agent prepared in S1 to 95mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0038] Example 3:

[0039] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0040] The structural formula of monomer A is R is -CH=CH2; monomer B is the same as in Example 1.

[0041] The method for preparing this conductive paste includes the following steps:

[0042] S1: Add 3g of carbon nanotubes and 3g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Then add it to a high-pressure homogenizer and run it at a pressure of 200Mpa for 30min. Then transfer it to a stirring container and add 3g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0043] S2: Add 1.5g monomer B and 9g of the modified conductive agent prepared in S1 to 89.5mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0044] Example 4:

[0045] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0046] The structural formula of monomer A is R is -C(CH3)=CH2; monomer B is the same as in Example 1.

[0047] The method for preparing this conductive paste includes the following steps:

[0048] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Add the suspension to a high-pressure homogenizer and run it at a pressure of 200Mpa for 50min. Then transfer it to a stirring container and add 4g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0049] S2: Add 2g of monomer B and 6g of the modified conductive agent prepared by S1 to 92mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0050] Example 5:

[0051] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0052] The structural formula of monomer A is R is -CH=CH2; monomer B is the same as in Example 1.

[0053] The method for preparing this conductive paste includes the following steps:

[0054] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Then add it to a high-pressure homogenizer and run it at a pressure of 100Mpa for 90min. Then transfer it to a stirring container and add 2g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0055] S2: Add 0.5g monomer B and 6g of the modified conductive agent prepared in S1 to 93.5mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0056] Example 6:

[0057] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0058] The structural formula of monomer A is R is -C(CH3)=CH2; monomer B is the same as in Example 1.

[0059] The method for preparing this conductive paste includes the following steps:

[0060] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Then add it to a high-pressure homogenizer and run it at a pressure of 100Mpa for 90min. Then transfer it to a stirring container and add 2g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0061] S2: Add 1g of acrylonitrile and 6g of the modified conductive agent prepared in S1 to 93.5mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0062] Example 7:

[0063] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0064] The structural formula of monomer A is R is -CH=CH2; monomer B is the same as in Example 1.

[0065] The method for preparing this conductive paste includes the following steps:

[0066] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Add the suspension to a high-pressure homogenizer and run it at a pressure of 50MPa for 90min. Then transfer it to a stirring container and add 2g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0067] S2: Add 1g of monomer B and 6g of the modified conductive agent prepared in S1 to 93mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0068] Example 8:

[0069] A high-solids-content conductive paste includes conductive carbon black, carbon nanotubes, a thickener, and a solvent. The thickener is polymerized from monomers A and B.

[0070] The structural formula of monomer A is R is -CH=CH2; monomer B is the same as in Example 1.

[0071] The method for preparing this conductive paste includes the following steps:

[0072] S1: Add 2g of carbon nanotubes and 2g of conductive carbon black to a mixed solvent of 200mL of deionized water and 50mL of ethanol to prepare a conductive suspension. Add the suspension to a high-pressure homogenizer and run it at a pressure of 200Mpa for 90min. Then transfer it to a stirring container and add 2g of monomer A. Stir for 2h and dry to obtain the modified conductive agent.

[0073] S2: Add 1g of monomer B and 6g of the modified conductive agent prepared in S1 to 93mL of N-methylpyrrolidone, stir thoroughly, then raise the temperature to 60℃, add 0.1g of azobisisobutyronitrile initiator, and continue stirring for 5h to obtain the conductive slurry.

[0074] Comparative Example 1

[0075] A method for preparing a conductive paste includes the following steps:

[0076] S1: Add 3g of polyvinylidene fluoride to 93mL of N-methylpyrrolidone, stir thoroughly, then add 2g of carbon nanotubes and 2g of conductive carbon black, and continue stirring for 5h to obtain the conductive slurry.

[0077] Experimental results:

[0078] Full cell preparation: The positive electrode sheet was prepared by mixing NCM:PVDF: the conductive slurry dry powder prepared in Examples 1-8 or Comparative Example 1 in a weight ratio of 98:1:1, and the negative electrode sheet was prepared by mixing graphite:CMC:SBR:SP in a ratio of 96:1.3:2.0:1.7. The electrolyte was 1.0 mol / L LiPF6 EC:DMC:EMC (volume ratio of 1:1:1) and additives. The separator was a PE membrane. The cells were then assembled into a full cell.

[0079] The test results are shown in the table below:

[0080]

[0081]

[0082] As can be seen from the table above, the conductive paste prepared by this patent has good dispersibility, which reduces the impedance of the electrode sheet.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A high-solids-content conductive paste, characterized in that, The product includes a conductive agent, a thickener, and a solvent. The thickener is polymerized from monomer A and monomer B, wherein the mass ratio of monomer A to monomer B is 1 to 4:1, and the structural formula of monomer A is one or more of formulas I, II, and III. 、 、 ； R, R1, and R2 are selected from -CH=CH2 and -C(CH3=CH2); The structural formula of the monomer B is shown in Formula IV; 2. The high-solids-content conductive paste according to claim 1, characterized in that, The conductive agent is one or more of graphene, carbon nanotubes, conductive carbon fibers, conductive carbon black, and conductive graphite.

3. The high-solids-content conductive paste according to claim 1, characterized in that, The mass ratio of the conductive agent, thickener, and solvent is 1–10: 1–5: 84–97.

4. A method for preparing a high-solids-content conductive paste according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Add the conductive agent to a mixture of deionized water and ethanol to prepare a conductive suspension. Then, add the conductive suspension to a high-pressure homogenizer and set the pressure and running time. Then, transfer it to a stirring container, add monomer A, stir for 1 to 3 hours, and dry to obtain the modified conductive agent. S2: Add the modified conductive agent prepared by monomers B and S1 to the solvent, stir thoroughly, then raise the temperature to 50-80℃, add azobisisobutyronitrile initiator, and continue stirring for 1-10 hours to obtain the conductive slurry.

5. The method for preparing the high-solids-content conductive paste according to claim 4, characterized in that, In step S1, the operating pressure of the high-pressure homogenizer is 50-200 MPa.

6. The method for preparing the high-solids-content conductive paste according to claim 4, characterized in that, The high-pressure homogenizer runs for 30 to 120 minutes in step S1.

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