Homogenizing process for efficiently preparing positive electrode slurry

Abstract

The invention discloses a homogenizing process for efficiently preparing positive electrode slurry, and relates to the technical field of positive electrode slurry preparation. Compared with an existing dry-method non-glue-making kneading process, a dry-method glue-making kneading process and a wet-method process scheme, the step-by-step double-circulation homogenizing method provided by the invention has the advantages that on the basis that the high-quality positive electrode slurry is obtained, the high-quality positive electrode slurry is obtained; the production efficiency can be greatly improved, after circulation of the circulation tank A, the circulation tank B, the stator and the rotor is finished, the slurry enters the circulation tank B to be continuously and finely dispersed, at the moment, the beat is finished, slurry homogenization of the next pot can be started, the whole beat time is about 1-2 h, slurry homogenization can be completed, and the efficiency is improved compared with that of a dry-method non-kneading process. The powder is added step by step, so that rapid infiltration and dispersion under high solid content are ensured, the dispersity of the slurry is better, the stability and uniformity of the slurry are improved, and the polarization internal resistance of a battery cell is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of positive electrode slurry preparation, and in particular to a slurry homogenization process for efficiently preparing positive electrode slurry. Background Art

[0002] With the rapid development of the new energy industry, the price of single energy storage and power battery cells has gradually dropped. Reducing costs and increasing efficiency is the top priority and one of the main means for an enterprise to survive in the fiercely competitive industry at this stage. Therefore, the demand for high-efficiency homogenization technology is more urgent.

[0003] There are three types of positive electrode homogenization processes that match the existing double planetary mixing equipment, namely dry non-gel kneading process, dry gel kneading process and wet process;

[0004] For the dry method without glue kneading process, the positive electrode needs to go through four steps of infiltration, kneading, high-viscosity dispersion and high-speed dispersion, and the overall process time is about 4 hours; the process is complex, the kneading process window is small, and it is greatly affected by the intrinsic properties of the material such as particle size and specific surface area. At the same time, the high solid content of kneading has high requirements on equipment; in this process, the positive electrode binder PVDF is in a dry powder state, which is not completely dissolved in the kneading stage, and the molecular chain is not completely opened, so there is less PVDF that is effectively kneaded, which leads to poor slurry stability after dispersion, a significant increase in viscosity, and the slurry is more likely to gel. In addition, the dry method of glue kneading is similar to the dry method without glue, and the process has one more step of glue making. Although the slurry has slightly better dispersibility, the overall process time is longer, about 5 hours. In addition, the wet process requires two steps of pre-dissolution and dispersion. The process is simple, but the process time is more than 7 hours, and the production efficiency is low. Summary of the invention

[0005] The object of the present invention is to provide a slurry homogenization process for efficiently preparing positive electrode slurry, so as to overcome the above-mentioned defects in the prior art.

[0006] A homogenization process for efficiently preparing positive electrode slurry comprises the following steps:

[0007] S1: Mix the active material, conductive agent and PVDF in advance in a mass ratio of 95-99%, 0.5-2.5% and 1-1.5%;

[0008] S2: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0009] S3: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed;

[0010] S4: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0011] S5: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed;

[0012] S6: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then the pre-fed 1 / 5 NMP is transported to the space between the stator and the rotor through a diaphragm pump at high speed, so as to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0013] S7: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed;

[0014] S8: The remaining 2 / 5 of NMP is transferred to circulation tank A, and then transferred to circulation tank B after 3-5 cycles of circulation tank A-circulation tank B-stator and rotor;

[0015] S9: Fine dispersion is further performed in circulation tank B, while circulation tank A can prepare the next batch of slurry.

[0016] Preferably, the active material used in step S1 is a positive electrode active material, and the positive electrode active material is any one of a ternary material, lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide;

[0017] Preferably, the ternary material is LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 、LiNi 0.8 Co 0.1 Al 0.1 O 2 、LiNi 0.8 Co0.15 Al 0.05 O 2 、LiNi 0.9 Co 0.05 Al 0.05 O 2 At least one of the materials.

[0018] Preferably, the conductive agent used in step S1 is a combination of one or more of Super p, acetylene black, CNT, and graphene.

[0019] Preferably, after each single circulation of 1 / 3 of the powder in steps S2, S4, and S6, the powder is transferred to the circulation tank B, and the equipment cycle is fully utilized for dispersion again.

[0020] The beneficial effects achieved by the present invention are:

[0021] The step-by-step double-circulation homogenization method proposed in the present application can achieve a substantial improvement in production efficiency on the basis of obtaining high-quality positive electrode slurry. After the circulation of circulation tank A-circulation tank B-stator and rotor is completed, the slurry enters circulation tank B for further fine dispersion. At this time, the cycle ends and the next batch of slurry homogenization can be started. The overall cycle time is about 1-2 hours to complete the slurry homogenization, and the efficiency is improved compared with the dry method without kneading process.

[0022] In addition, the step-by-step addition of powder ensures rapid wetting and dispersion at high solid content, which is conducive to better dispersion of the slurry, improving the stability and uniformity of the slurry and reducing the polarization internal resistance of the battery cell.

[0023] The efficiency of preparing slurry by using the process method proposed in this application is greatly improved, the stability of the slurry is improved, the coating effect is improved, the production efficiency is improved, and the consistency of lithium-ion batteries is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a process flow chart of the present invention as a whole.

[0025] Figure 2 It is a line graph showing the viscosity change of the lithium iron phosphate slurry of the present invention.

[0026] Figure 3 It is a line graph showing the viscosity change of the lithium cobalt oxide slurry of the present invention.

[0027] Figure 4 LiNi 0.5 Co 0.2 Mn 0.3 O 2 Line graph of slurry viscosity variation. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention.

[0029] Embodiment 1,

[0030] A homogenization process for efficiently preparing positive electrode slurry comprises the following steps:

[0031] S1: Mix lithium iron phosphate, conductive agent and PVDF in a mass ratio of 98%, 1% and 1% in advance;

[0032] S2: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0033] S3: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0034] S4: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0035] S5: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0036] S6: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0037] S7: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0038] S8: The remaining 2 / 5 of NMP is transferred to circulation tank A, and then transferred to circulation tank B after 3-5 cycles of circulation tank A-circulation tank B-stator and rotor;

[0039] S9: finely disperse the slurry in the circulation tank B to prepare slurry A;

[0040] Among them, during the preparation process, the viscosity of the lithium iron phosphate slurry changes as follows Figure 1 shown.

[0041] Embodiment 2,

[0042] A homogenization process for efficiently preparing positive electrode slurry comprises the following steps:

[0043] S1: Mix lithium cobalt oxide, conductive agent and PVDF in a mass ratio of 98%, 1% and 1% in advance;

[0044] S2: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0045] S3: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0046] S4: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0047] S5: After 1 / 3 of the powder is completely discharged, it is circulated through the stator and rotor of the circulation tank A for 3-5 times, and then transferred to the circulation tank B, where high-speed dispersion is maintained;

[0048] S6: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0049] S7: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0050] S8: The remaining 2 / 5 of NMP is transferred to circulation tank A, and then transferred to circulation tank B after 3-5 cycles of circulation tank A-circulation tank B-stator and rotor;

[0051] S9: finely dispersing in the circulation tank B to prepare slurry B;

[0052] Among them, during the preparation process, the viscosity of the lithium cobalt oxide slurry changes as follows Figure 2 shown.

[0053] Embodiment 3,

[0054] A homogenization process for efficiently preparing positive electrode slurry comprises the following steps:

[0055] S1: The first active LiNi 0.5 Co 0.2 Mn 0.3 O 2 , conductive agent, and PVDF are mixed in advance in a mass ratio of 98%, 1%, and 1%;

[0056] S2: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0057] S3: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0058] S4: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0059] S5: After 1 / 3 of the powder is completely discharged, it is circulated through the stator and rotor of the circulation tank A for 3-5 times, and then transferred to the circulation tank B, where high-speed dispersion is maintained;

[0060] S6: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation;

[0061] S7: After 1 / 3 of the powder is completely discharged, it is circulated through the circulation tank A-stator and rotor for 3-5 times, and then transferred to the circulation tank B, and the circulation tank B is kept dispersed at a high speed;

[0062] S8: The remaining 2 / 5 of NMP is transferred to circulation tank A, and then transferred to circulation tank B after 3-5 cycles of circulation tank A-circulation tank B-stator and rotor;

[0063] S9: finely disperse the slurry in the circulation tank B to prepare slurry C;

[0064] Among them, during the preparation process, LiNi 0.5 Co 0.2 Mn 0.3 O 2 The viscosity of the slurry changes as Figure 3shown.

[0065] In summary, compared with the existing dry method without glue kneading process, dry method with glue kneading process and wet process, the step-by-step double-circulation homogenization method proposed in the present invention can achieve a significant improvement in production efficiency on the basis of obtaining high-quality positive electrode slurry. After the circulation of circulation tank A-circulation tank B-stator and rotor is completed, the slurry enters circulation tank B for further fine dispersion. At this time, the beat ends and the next pot of slurry homogenization can be started. The overall beat time is about 1-2h to complete the homogenization of the slurry, and the efficiency is improved compared with the dry method without kneading process.

[0066] In addition, the step-by-step addition of powder ensures rapid wetting and dispersion at high solid content, which is conducive to better dispersion of the slurry, improving the stability and uniformity of the slurry and reducing the polarization internal resistance of the battery cell.

[0067] The efficiency of preparing slurry using the process method proposed in this patent is greatly improved, the stability of the slurry is improved, the coating effect is improved, the production efficiency is improved, and the consistency of lithium-ion batteries is ensured.

[0068] The above-described embodiments of the present invention do not constitute a limitation on the protection scope of the present invention. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A homogenization process for efficiently preparing positive electrode slurry, characterized in that: The steps include: S1: Mix the active material, conductive agent and PVDF in advance in a mass ratio of 95-99%, 0.5-2.5% and 1-1.5%; S2: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation; S3: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed; S4: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then 1 / 5 NMP is transported between the stator and the rotor at high speed through a diaphragm pump to quickly wet the dispersed powder and carry it to the circulation tank A through circulation; S5: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed; S6: 1 / 3 of the mixed powder is first fed and dispersed into a dispersed state through the stator and rotor, and then the pre-fed 1 / 5 NMP is transported to the space between the stator and the rotor through a diaphragm pump at high speed, so as to quickly wet the dispersed powder and carry it to the circulation tank A through circulation; S7: After 1 / 3 of the powder is completely discharged, a single cycle is performed 3-5 times through the circulation tank A-stator and rotor, and then transferred to the circulation tank B and the circulation tank B is kept dispersed at a high speed; S8: The remaining 2 / 5 of NMP is transferred to circulation tank A, and then transferred to circulation tank B after 3-5 cycles of circulation tank A-circulation tank B-stator and rotor; S9: Fine dispersion is further performed in circulation tank B, while circulation tank A can prepare the next batch of slurry.

2. The homogenization process for efficiently preparing positive electrode slurry according to claim 1, characterized in that: The active material used in step S1 is a positive electrode active material, and the positive electrode active material is any one of a ternary material, lithium iron phosphate, lithium cobalt oxide, and lithium manganese oxide.

3. The homogenization process for efficiently preparing positive electrode slurry according to claim 2, characterized in that: The ternary material is LiNi 0.5 Co 0.2 Mn 0.3 O2、LiNi 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 0.8 Co 0.1 Al 0.1 O2、LiNi 0.8 Co 0.15 Al 0.05 O2、LiNi 0.9 Co 0.05 Al 0.05 At least one of the O2 materials.

4. The homogenization process for efficiently preparing positive electrode slurry according to claim 1, characterized in that: The conductive agent used in step S1 is a combination of one or more of Super p, acetylene black, CNT, and graphene.

5. The homogenization process for efficiently preparing positive electrode slurry according to claim 1, characterized in that: After each single cycle of 1 / 3 of the powder in steps S2, S4, and S6 is completed, it is transferred to the circulation tank B and dispersed again by making full use of the equipment cycle.

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