CN111599985A - Lithium ion battery slurry, preparation method thereof and lithium ion battery - Google Patents
Lithium ion battery slurry, preparation method thereof and lithium ion battery Download PDFInfo
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- CN111599985A CN111599985A CN202010468292.7A CN202010468292A CN111599985A CN 111599985 A CN111599985 A CN 111599985A CN 202010468292 A CN202010468292 A CN 202010468292A CN 111599985 A CN111599985 A CN 111599985A
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- 239000002002 slurry Substances 0.000 title claims abstract description 121
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 63
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 63
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 239000003292 glue Substances 0.000 claims abstract description 58
- 239000007787 solid Substances 0.000 claims abstract description 47
- 238000002156 mixing Methods 0.000 claims abstract description 38
- 239000000843 powder Substances 0.000 claims abstract description 37
- 239000006258 conductive agent Substances 0.000 claims abstract description 28
- 239000000203 mixture Substances 0.000 claims abstract description 21
- 239000013543 active substance Substances 0.000 claims abstract description 16
- 239000011230 binding agent Substances 0.000 claims abstract description 15
- 239000002904 solvent Substances 0.000 claims abstract description 15
- 238000003756 stirring Methods 0.000 claims description 62
- 238000000034 method Methods 0.000 claims description 29
- 239000011267 electrode slurry Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 238000004898 kneading Methods 0.000 claims description 17
- 239000007773 negative electrode material Substances 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 10
- 229920003063 hydroxymethyl cellulose Polymers 0.000 claims description 8
- 229940031574 hydroxymethyl cellulose Drugs 0.000 claims description 8
- 239000010439 graphite Substances 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 238000012360 testing method Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000006230 acetylene black Substances 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 239000007772 electrode material Substances 0.000 claims description 3
- 239000003273 ketjen black Substances 0.000 claims description 2
- 239000006185 dispersion Substances 0.000 abstract description 12
- 230000008569 process Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 239000006257 cathode slurry Substances 0.000 description 6
- 239000002174 Styrene-butadiene Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000009736 wetting Methods 0.000 description 4
- 238000007580 dry-mixing Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 239000002562 thickening agent Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011268 mixed slurry Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses lithium ion battery slurry, a preparation method thereof and a lithium ion battery. The preparation method comprises the following steps: 1) mixing an electrode active substance and a conductive agent to obtain a dry powder mixture; 2) adding glue solution into the dry powder mixture, and mixing to obtain first slurry, wherein the kneaded solid content of the first slurry is 55-75%; 3) adding glue solution into the first slurry, and mixing to obtain second slurry; 4) and adding a solvent into the second slurry, mixing to adjust the viscosity, adding a binder, and mixing to obtain the lithium ion battery slurry. The slurry provided by the invention has excellent dispersion uniformity and slurry stability.
Description
Technical Field
The invention belongs to the technical field of batteries, and relates to lithium ion battery slurry, a preparation method thereof and a lithium ion battery.
Background
For a lithium ion battery taking lithium iron phosphate as a positive active material, the negative active material generally adopts graphite, and the preparation process of the current lithium ion battery negative electrode slurry is roughly divided into two types: (1) the wet mixing process includes the basic steps of preparing glue solution, adding conducting agent, mixing, adding active matter, mixing and adding SBR. This is the mainstream technology in China at present. (2) The dry mixing process includes preparing glue solution, mixing active matter and conducting agent powder, wetting with glue solution, adding solvent to disperse and crush, diluting to regulate viscosity and mixing with SBR.
For the lithium ion battery cathode slurry, the dispersion effect directly influences the processing performance of subsequent slurry, and further influences the performance of subsequent batteries. The two preparation methods of the cathode slurry have different influences on the dispersion uniformity of the slurry and have different degrees of influences on the binding power of the prepared pole piece.
In the wet mixing process, the active substances are mixed for a short time and cannot sufficiently absorb liquid, the specific surface area of the conductive agent is far larger than that of active substance particles, a large amount of liquid is absorbed on the surface of the conductive agent, and the conductive agent cannot easily flow, so that the dispersion uniformity of the slurry is poor. In the dry mixing process, active substances and conductive agent powder are preferably uniformly mixed, and after the glue solution is subsequently added, the active substances and the conductive agent simultaneously absorb liquid, the liquid absorption degrees of the active substances and the conductive agent are the same, and the uniformity of the slurry under the condition is better, but the energy consumption of stirring equipment is improved in the wetting and kneading stage in the method.
CN102280612A discloses a preparation method of lithium battery negative electrode slurry and a prepared lithium ion battery, which includes: dissolving non-ionic water-soluble cellulose powder in water to prepare a glue solution, and adding a defoaming agent into the glue solution. The scheme also discloses the lithium ion battery prepared from the lithium ion battery cathode slurry prepared by the method. The method
CN102790218A discloses a preparation process of lithium ion battery cathode slurry. The steps of the scheme are as follows: taking 88-96 parts by weight of negative active material, 4.8-6 parts by weight of binder, 1.0-1.7 parts by weight of thickener, 0-5.5 parts by weight of conductive agent, 70.4-115.2 parts by weight of solvent and 0.88-5.76 parts by weight of additive as raw materials; adding the thickening agent into the solvent and stirring for 2.5-4.5 hours; adding a conductive agent and stirring for 3-5 hours; adding the negative active material for several times and stirring for 2.5-4 hours; adding the additive and stirring for 20-60 minutes; adding the binder, stirring for 1.5-3 hours, and sieving to obtain the cathode slurry.
CN108630884A discloses a preparation method of a lithium ion battery negative electrode slurry, which comprises the following steps: step S1, preparing materials: weighing a negative active material powder material, a conductive agent, a powder binder, a liquid binder and a solvent for later use; step S2, preparing uniform glue solution: adding the powder binder and 40-60% of solvent into stirring equipment, and stirring to obtain uniform glue solution; step S3, stirring the asphalt slurry: adding a negative active material powder material and a conductive agent into the uniform glue solution in the step S2, stirring, and mixing the active material powder and the glue solution to obtain an asphalt-like slurry; step S4, running-in stirring: adding 20-40% of solvent into the asphalt slurry obtained in the step S3, continuously mixing, and grinding and stirring; step S5, adjusting viscosity: and (5) adding 20-40% of solvent into the slurry obtained in the step S4 to enable the viscosity to be 2000-6000 mPa.
However, the slurry prepared by the scheme has the advantages of further improvement of the dispersion uniformity and the slurry stability.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a lithium ion battery slurry, a preparation method thereof, and a lithium ion battery. The preparation method provided by the invention can obtain the lithium ion battery slurry with uniform dispersion and stable performance, and obtain the optimal kneading state in the dry mixing process.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a slurry for a lithium ion battery, the method comprising the steps of:
(1) mixing an electrode active substance and a conductive agent to obtain a dry powder mixture;
(2) adding glue solution into the dry powder mixture obtained in the step (1), and mixing to obtain first slurry, wherein the kneaded solid content of the first slurry is 55-75%;
(3) adding glue solution into the first slurry obtained in the step (2), and mixing to obtain a second slurry;
(4) and (4) adding a solvent into the second slurry obtained in the step (3), mixing, adjusting the viscosity, adding a binder, and mixing to obtain the lithium ion battery slurry.
In the preparation method provided by the invention, the electrode active substance and the conductive agent are preferably uniformly mixed in a dry powder state, the glue solution is added, and at the moment, the active substance and the conductive agent simultaneously absorb liquid and wet solid particles.
In the preparation method provided by the invention, in the wetting and kneading process in the step (2), the addition amount of the glue solution can be properly adjusted according to the actual dryness and wetness of the slurry, and meanwhile, the energy consumption condition of the equipment is judged by observing the current condition of the stirring equipment, so that the loss of the equipment is reduced.
In the invention, the significance of adding the glue solution in the steps (2) and (3) twice is as follows: the first glue adding is to ensure that the slurry is in a moderate dry and wet state so as to facilitate the kneading process, so that various substances in the slurry are not agglomerated in the kneading process. The second glue adding is to make the slurry in a kneaded state converted into a solution state, so that various components of the slurry can be uniformly dispersed in the rapid dispersion process.
In the preparation method provided by the invention, the kneaded solid content of the first slurry in the step (2) is 55-75%, such as 55%, 58%, 60%, 62%, 64%, 68%, 70%, 72% or 75%, and the like, and the range can enable the prepared slurry to have small viscosity fluctuation in the preservation process, good slurry stability and good slurry dispersion effect, and the subsequently prepared pole piece has excellent stripping force and pole piece adhesion force. If the kneading solid content is too high or too low, the slurry dispersion effect is impaired, and the slurry stability is deteriorated.
In the present invention, the kneaded solid content refers to a solid content when the electrode active material and the conductive agent are mixed into a dough state after a proper amount of glue solution is added after forming a dry powder mixture.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
As a preferred technical scheme of the invention, the lithium ion battery slurry is a lithium ion battery cathode slurry.
Preferably, the electrode active material of step (1) includes a graphite negative electrode material.
Preferably, the conductive agent of step (1) comprises acetylene black and/or ketjen black;
preferably, the mixing in step (1) is stirring mixing.
In the preferred embodiment of the present invention, the operation temperature in step (2), step (3) and step (4) is independently 23 to 27 ℃, for example, 23 ℃, 23.5 ℃, 24 ℃, 24.5 ℃, 25 ℃, 25.5 ℃, 26 ℃, 26.5 ℃ or 27 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, in step (2), step (3) and step (4), the mixing is stirring mixing.
Preferably, in step (3) and step (4), the mixing is performed under vacuum. In the invention, the vacuum pumping operation is adopted during mixing, because air bubbles are easily generated in the slurry during the mixing process, if the air bubbles are not removed, the air bubbles appear on the surface of the pole piece during the subsequent coating process, and the cold pressing causes the foil exposure of the pole piece, thereby causing the poor pole piece. For example, the stirring cylinder is vacuumized in the mixing methods such as the rapid dispersion and slow stirring processes, so that air bubbles in the slurry can be removed, and the appearance of the subsequent pole piece of the slurry is not affected.
Preferably, in step (3) and step (4), the degree of vacuum of the mixing is independently ≦ 0.085MPa, e.g., -0.085MPa, -0.086MPa, -0.087MPa, -0.088MPa, -0.089MPa, or-0.09 MPa, and the like.
As a preferable technical scheme of the invention, the solvent of the glue solution in the step (2) comprises water.
Preferably, the solute of the glue solution of step (2) comprises hydroxymethyl cellulose (CMC).
In the invention, the solute of the glue solution is selected from hydroxymethyl cellulose (CMC) because CMC can be used as a dispersant to disperse electrode active substances and conductive agents (electrode active substances such as graphite and the like are not hydrophilic and are difficult to disperse in a water system), and in addition, CMC can form gel in water to thicken the slurry and play a role of a thickener, so that when the glue solution is coated on a large scale, the glue solution can not only retain water but also stabilize the slurry, can maintain the uniformity of the slurry within a certain time and is beneficial to large-scale production because the gel structure exists.
Preferably, the mass fraction of the solute in the dope solution in the step (2) is 1-2%, such as 1%, 1.2%, 1.4%, 1.6%, 1.8%, or 2%, but not limited to the recited values, and other non-recited values in the range of the recited values are also applicable.
The preparation method of the glue solution in the step (2) can be as follows: adding the solute dry powder into a solvent, uniformly dispersing by using stirring equipment to prepare a glue solution, and taking out for later use.
As a preferred embodiment of the present invention, the kneaded solid content of the first slurry in the step (2) is 60 to 70%, for example, 60%, 62%, 64%, 68%, or 70%, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable. The kneading solid content range of the first slurry in the range of the invention is the optimal range, and the slurry prepared by adopting the kneading solid content range has small 24-hour fluctuation and better slurry stability, which indicates that the dispersion effect of the slurry is better; the pole piece obtained subsequently has better stripping force and better pole piece bonding force.
In the invention, in the actual operation process, the kneading state can be judged to be proper or not through visual observation, the proper kneading state is a dough with moderate dryness and wetness, and the slurry is in the dough state when kneaded by hands, so that the slurry is not cracked or loosened, and is not in a wet or fluid state. But more precise methods are also specific to determining the actual solids content.
Preferably, the glue solution in the step (2) has the same composition as the glue solution in the step (3).
Preferably, the mass fraction of the dope of the step (2) is 50 to 60 wt%, such as 50 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt% or 60 wt%, based on 100% of the total mass of the dope of the step (2) and the dope of the step (3), but not limited to the enumerated values, and other non-enumerated values in the numerical range are also applicable; the mass fraction of the dope of the step (3) is 40 to 50 wt%, for example 40 wt%, 42 wt%, 44 wt%, 46 wt%, 48 wt% or 50 wt%, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferred technical scheme of the invention, the solvent in the step (4) comprises water.
Preferably, the viscosity adjustment described in step (4) adjusts the slurry viscosity to 2000-5000 mPas, such as 2000 mPas, 3000 mPas, 4000 mPas or 5000 mPas, but not limited to the recited values, and other values not recited within the range are equally applicable.
As a preferred technical scheme of the invention, the binder in the step (4) comprises Styrene Butadiene Rubber (SBR). SBR can be matched with CMC. The SBR emulsion is soluble in water, and the SBR is a flexible material and has good adhesive property, so that the pole piece is not pulverized under the condition of high compaction, and the pole piece after rolling has high adhesive strength.
Preferably, the lithium ion battery slurry in step (4) has a solid content of 45-55%, such as 45%, 47%, 50%, 52%, or 55%, but not limited to the recited values, and other values in the range are also applicable.
As a further preferable technical scheme of the preparation method, the method comprises the following steps:
(1) adding dry hydroxymethyl cellulose powder into water, stirring and dispersing by using stirring equipment to obtain a glue solution with the mass fraction of 1-2%, and taking out for later use;
(2) adding the negative active material and the conductive agent dry powder into a stirring device according to a proportion, and stirring to obtain a dry powder mixture;
(3) adding 50-60 wt% of the total amount of the glue solution in the step (1) into the dry powder mixture in the step (2), stirring and dispersing to ensure that the solid content of kneading is 60-70% at the moment, and obtaining first slurry;
(4) adding 40-50 wt% of the total amount of the glue solution in the step (1) into the first slurry in the step (3), and stirring and dispersing to obtain a second slurry;
(5) testing the viscosity of the slurry, adding water, stirring and dispersing to adjust the viscosity, and controlling the viscosity of the slurry to be 2000-5000mPa & s;
(6) adding a binder, and stirring and dispersing to obtain the lithium ion battery slurry;
wherein, the stirring in the step (1), the step (4), the step (5) and the step (6) is carried out under the condition of vacuum pumping.
In a second aspect, the invention provides a lithium ion battery slurry obtained by the preparation method of the first aspect.
In a third aspect, the present invention provides a lithium ion battery prepared using the lithium ion battery slurry of the second aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) in the preparation method provided by the invention, the electrode active substance and the conductive agent are preferably uniformly mixed in a dry powder state, the glue solution is added, and at the moment, the active substance and the conductive agent simultaneously absorb liquid and wet solid particles. In the wetting kneading process, the addition of the glue solution can be properly adjusted according to the actual dryness and wetness of the slurry, and the energy consumption condition of the equipment can be judged by observing the current condition of the stirring equipment, so that the loss of the equipment is reduced.
(2) The slurry provided by the invention has excellent dispersion uniformity and slurry stability.
Drawings
Fig. 1 is a viscosity stability graph of the lithium ion battery negative electrode slurry provided in example 1;
fig. 2 is a solid content stability graph of the lithium ion battery negative electrode slurry provided in example 1.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
The following are typical but non-limiting examples of the invention:
example 1
In this example, an electrode slurry for a lithium ion battery was prepared as follows:
(1) adding dry powder of hydroxymethyl cellulose into water, stirring and dispersing at-0.085 MPa vacuum degree and 25 deg.C to obtain 1.5% glue solution, and taking out;
(2) adding graphite serving as a negative active material and acetylene black dry powder serving as a conductive agent into stirring equipment according to a mass ratio of 96.5:1, and stirring to obtain a dry powder mixture;
(3) adding 55 wt% of the total amount of the glue solution in the step (1) into the dry powder mixture in the step (2), stirring and dispersing at 25 ℃, and ensuring that the solid content of kneading is 65% at the moment to obtain a first slurry;
(4) adding 45 wt% of the total amount of the glue solution in the step (1) into the first slurry in the step (3), and stirring and dispersing under the vacuum degree of-0.085 MPa and the temperature of 25 ℃ to obtain second slurry;
(5) testing the viscosity of the slurry, adding water, stirring and dispersing under the vacuum degree of-0.085 MPa and at the temperature of 25 ℃ to adjust the viscosity, and controlling the viscosity of the slurry to be 3500mPa & s;
(6) adding styrene butadiene rubber serving as a binder, and stirring and dispersing at the vacuum degree of-0.085 MPa and the temperature of 25 ℃ to obtain the lithium ion battery negative electrode slurry, wherein the solid content of the lithium ion battery negative electrode slurry is 50%.
Fig. 1 is a viscosity stability graph of the lithium ion battery negative electrode slurry provided in this example, and it can be seen from the graph that the standing viscosity of the slurry increases by 4000mPa · s within 24 hours, and for the negative electrode slurry, the viscosity change of the slurry is small, and the slurry is stable.
Fig. 2 is a solid content stability graph of the lithium ion battery negative electrode slurry provided in this embodiment, and it can be seen from the graph that the solid content of the slurry after standing is changed within 0.8% within 24 hours, which indicates that the slurry is in a relatively stable state during the standing process and does not settle.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 2
In this example, an electrode slurry for a lithium ion battery was prepared as follows:
(1) adding dry powder of hydroxymethyl cellulose into water, stirring and dispersing at-0.086 MPa vacuum degree and 23 ℃ by using stirring equipment to obtain glue solution with mass fraction of 1%, and taking out for later use;
(2) adding the negative active material graphite and the conductive agent acetylene black dry powder into stirring equipment according to the mass ratio of 95:1, and stirring to obtain a dry powder mixture;
(3) adding 50 wt% of the total amount of the glue solution in the step (1) into the dry powder mixture in the step (2), stirring and dispersing at 25 ℃, and ensuring that the solid content of kneading is 65% at the moment to obtain a first slurry;
(4) adding 50 wt% of the total amount of the glue solution in the step (1) into the first slurry in the step (3), and stirring and dispersing under the vacuum degree of-0.087 MPa and the temperature of 23 ℃ to obtain second slurry;
(5) testing the viscosity of the slurry, adding water, stirring and dispersing under the vacuum degree of-0.088 MPa and the temperature of 23 ℃ to adjust the viscosity, and controlling the viscosity of the slurry to be 2000mPa & s;
(6) adding styrene butadiene rubber serving as a binder, and stirring and dispersing at a vacuum degree of-0.085 MPa and a temperature of 23 ℃ to obtain the lithium ion battery negative electrode slurry, wherein the solid content of the lithium ion battery negative electrode slurry is 55%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 3
In this example, an electrode slurry for a lithium ion battery was prepared as follows:
(1) adding dry powder of hydroxymethyl cellulose into water, stirring and dispersing at-0.085 MPa vacuum degree and 27 ℃ by using stirring equipment to obtain glue solution with the mass fraction of 1%, and taking out for later use;
(2) adding graphite serving as a negative electrode active material and Keqin black dry powder serving as a conductive agent into stirring equipment according to a mass ratio of 98:1, and stirring to obtain a dry powder mixture;
(3) adding 60 wt% of the total amount of the glue solution in the step (1) into the dry powder mixture in the step (2), stirring and dispersing at 27 ℃, and ensuring that the solid content of kneading is 65% at the moment to obtain a first slurry;
(4) adding 40 wt% of the total amount of the glue solution in the step (1) into the first slurry in the step (3), and stirring and dispersing under-0.088 MPa of vacuum degree and 27 ℃ to obtain a second slurry;
(5) testing the viscosity of the slurry, adding water, stirring and dispersing under the vacuum degree of-0.086 MPa and the temperature of 27 ℃ to adjust the viscosity, and controlling the viscosity of the slurry to be 5000mPa & s;
(6) adding styrene butadiene rubber serving as a binder, and stirring and dispersing at the vacuum degree of-0.085 MPa and the temperature of 27 ℃ to obtain the lithium ion battery negative electrode slurry, wherein the solid content of the lithium ion battery negative electrode slurry is 45%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 4
This example was carried out in the same manner as in example 1 except that the kneaded solid content in step (3) was 60%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 5
This example was carried out in the same manner as in example 1 except that the kneaded solid content in step (3) was 70%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 6
This example was carried out in the same manner as in example 1 except that the kneading solids content in step (3) was 55%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Example 7
This example was carried out in the same manner as in example 1 except that the kneaded solid content in step (3) was 75%.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the embodiment within 24h are shown in table 1.
Comparative example 1
The method for preparing a lithium ion battery negative electrode slurry of this comparative example refers to example 3 except that, instead of performing the operations of step (3) and step (4) of example 3, a slurry having the same mass and composition as the sum of the slurry solutions of step (3) and step (4) of example 3 is added at a time to a dry powder mixture having the same amount as that of step (3) of example 3 after step (2) of example 3, and is stirred and dispersed at the same temperature and vacuum degree as that of step (3) of example 3 to obtain a mixed slurry, and then the subsequent steps of example 3 are performed by replacing the second slurry of example 3 with the mixed slurry.
The maximum fluctuation values of the viscosity and the solid content of the lithium ion battery negative electrode slurry finally obtained in the comparative example within 24h are shown in table 1.
Test method
The lithium ion battery pastes provided in the examples and comparative examples were tested as follows:
the lithium ion battery slurries provided in each of examples and comparative examples were tested for viscosity over 24 hours using a digital viscometer at a temperature of 25. + -. 2 ℃ and a humidity of < 30%, and samples were taken every two hours for a total of 13 samples, and the difference between the maximum value and the minimum value of the viscosity among the 13 samples was compared as the maximum value of fluctuation.
The lithium ion battery slurry provided in each example and comparative example was tested for solid content in 24 hours using a weight loss method in a heating oven, and samples were taken every two hours for a total of 13 samples, and the difference between the maximum value and the minimum value of the solid content in the 13 samples was compared as the maximum value of fluctuation.
The test results are given in the following table:
TABLE 1
As is clear from a combination of the above examples and comparative examples, in the production methods of examples 1 to 5, the kneaded solid content of the first slurry was appropriate, and the gum solution was added in two portions, which is advantageous in improving the product properties. The electrode active substance and the conductive agent are uniformly mixed in a dry powder state preferentially, and then the glue solution is added, at the moment, the active substance and the conductive agent simultaneously absorb liquid and wet solid particles.
The first slurry kneaded solid content of example 6 was slightly lower and the first slurry kneaded solid content of example 7 was slightly higher, which resulted in a decrease in the dispersibility of the slurries and a decrease in the stability of the slurries of examples 6 and 7 as compared to examples 1, 4 and 5, but the overall performance was still excellent.
Comparative example 1 not only did not control the kneaded solid content of the first slurry, but even added the gum solution only once, which resulted in a large fluctuation in the viscosity of the slurry for 24 hours, with insignificant fluctuation in the solid content, indicating that the slurry stability was inferior to that of the slurry in example 3.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A preparation method of lithium ion battery slurry is characterized by comprising the following steps:
(1) mixing an electrode active substance and a conductive agent to obtain a dry powder mixture;
(2) adding glue solution into the dry powder mixture obtained in the step (1), and mixing to obtain first slurry, wherein the kneaded solid content of the first slurry is 55-75%;
(3) adding glue solution into the first slurry obtained in the step (2), and mixing to obtain a second slurry;
(4) and (4) adding a solvent into the second slurry obtained in the step (3), mixing, adjusting the viscosity, adding a binder, and mixing to obtain the lithium ion battery slurry.
2. The preparation method according to claim 1, wherein the lithium ion battery slurry is a lithium ion battery negative electrode slurry;
preferably, the electrode active material of step (1) includes a graphite negative electrode material;
preferably, the conductive agent of step (1) comprises acetylene black and/or ketjen black;
preferably, the mixing in step (1) is stirring mixing.
3. The production method according to claim 1 or 2, wherein in the step (2), the step (3) and the step (4), the operating temperature is independently 23 to 27 ℃;
preferably, in the step (2), the step (3) and the step (4), the mixing is stirring mixing;
preferably, in step (3) and step (4), the mixing is carried out under the condition of vacuum pumping;
preferably, in step (3) and step (4), the vacuum of the mixing is independently ≦ 0.085 MPa.
4. The preparation method according to any one of claims 1 to 3, wherein the solvent of the glue solution of step (2) comprises water;
preferably, the solute of the glue solution in the step (2) comprises hydroxymethyl cellulose;
preferably, in the glue solution in the step (2), the mass fraction of the solute is 1-2%.
5. The production method according to any one of claims 1 to 4, characterized in that the kneaded solid content of the first slurry of step (2) is 60 to 70%;
preferably, the glue solution in the step (2) has the same composition as the glue solution in the step (3);
preferably, the mass fraction of the glue solution in the step (2) is 50-60 wt% and the mass fraction of the glue solution in the step (3) is 40-50 wt% based on 100% of the total mass of the glue solution in the step (2) and the glue solution in the step (3).
6. The production method according to any one of claims 1 to 5, wherein the solvent of step (4) comprises water;
preferably, the viscosity adjustment in the step (4) adjusts the viscosity of the slurry to 2000-5000 mPas.
7. The method according to any one of claims 1 to 6, wherein the binder of step (4) comprises styrene butadiene rubber;
preferably, the solid content of the lithium ion battery slurry in the step (4) is 45-55%.
8. The method for preparing according to any one of claims 1 to 7, characterized in that it comprises the steps of:
(1) adding dry hydroxymethyl cellulose powder into water, stirring and dispersing by using stirring equipment to obtain a glue solution with the mass fraction of 1-2%, and taking out for later use;
(2) adding the negative active material and the conductive agent dry powder into a stirring device according to a proportion, and stirring to obtain a dry powder mixture;
(3) adding 50-60 wt% of the total amount of the glue solution in the step (1) into the dry powder mixture in the step (2), stirring and dispersing to ensure that the solid content of kneading is 60-70% at the moment, and obtaining first slurry;
(4) adding 40-50 wt% of the total amount of the glue solution in the step (1) into the first slurry in the step (3), and stirring and dispersing to obtain a second slurry;
(5) testing the viscosity of the slurry, adding water, stirring and dispersing to adjust the viscosity, and controlling the viscosity of the slurry to be 2000-5000mPa & s;
(6) adding a binder, and stirring and dispersing to obtain the lithium ion battery slurry;
wherein, the stirring in the step (1), the step (4), the step (5) and the step (6) is carried out under the condition of vacuum pumping.
9. A lithium ion battery paste obtained by the production method according to any one of claims 1 to 8.
10. A lithium ion battery prepared by using the lithium ion battery slurry according to claim 9.
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| CN113363470A (en) * | 2021-05-25 | 2021-09-07 | 东莞维科电池有限公司 | Method for quickly obtaining appropriate range of solid content in slurry kneading and application |
| CN114204110A (en) * | 2021-12-13 | 2022-03-18 | 惠州亿纬锂能股份有限公司 | Composite solid electrolyte, preparation method thereof and lithium ion battery |
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| CN112885983A (en) * | 2021-01-14 | 2021-06-01 | 天能帅福得能源股份有限公司 | Lithium ion battery positive electrode slurry homogenizing method |
| CN113097424A (en) * | 2021-02-24 | 2021-07-09 | 云南航开科技有限公司 | High-recovery battery negative electrode slurry, preparation method thereof and lithium battery |
| CN113363470A (en) * | 2021-05-25 | 2021-09-07 | 东莞维科电池有限公司 | Method for quickly obtaining appropriate range of solid content in slurry kneading and application |
| CN114204110A (en) * | 2021-12-13 | 2022-03-18 | 惠州亿纬锂能股份有限公司 | Composite solid electrolyte, preparation method thereof and lithium ion battery |
| WO2024098419A1 (en) * | 2022-11-11 | 2024-05-16 | 宁德时代新能源科技股份有限公司 | Preparation method for positive electrode slurry, secondary battery, battery pack and electrical apparatus |
| WO2024120497A1 (en) * | 2022-12-07 | 2024-06-13 | 惠州亿纬锂能股份有限公司 | Aqueous homogenization process for positive electrode system of lithium-ion battery, slurry and lithium-ion battery |
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