CN109192923A - A kind of preparation method of negative electrode of lithium ion battery electrocondution slurry - Google Patents
A kind of preparation method of negative electrode of lithium ion battery electrocondution slurry Download PDFInfo
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- CN109192923A CN109192923A CN201811119429.7A CN201811119429A CN109192923A CN 109192923 A CN109192923 A CN 109192923A CN 201811119429 A CN201811119429 A CN 201811119429A CN 109192923 A CN109192923 A CN 109192923A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 47
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 37
- 238000003756 stirring Methods 0.000 claims abstract description 126
- 238000002156 mixing Methods 0.000 claims abstract description 73
- 238000000034 method Methods 0.000 claims abstract description 51
- 239000006258 conductive agent Substances 0.000 claims abstract description 41
- 239000011230 binding agent Substances 0.000 claims abstract description 36
- 239000002904 solvent Substances 0.000 claims abstract description 31
- 239000011267 electrode slurry Substances 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 21
- 239000007787 solid Substances 0.000 claims abstract description 21
- 239000011149 active material Substances 0.000 claims abstract description 15
- 239000011268 mixed slurry Substances 0.000 claims abstract description 8
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical group O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
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- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 28
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 27
- 238000000498 ball milling Methods 0.000 claims description 26
- 239000002518 antifoaming agent Substances 0.000 claims description 25
- 239000013543 active substance Substances 0.000 claims description 24
- 229910052710 silicon Inorganic materials 0.000 claims description 24
- 239000010703 silicon Substances 0.000 claims description 24
- 229910052799 carbon Inorganic materials 0.000 claims description 23
- 239000007788 liquid Substances 0.000 claims description 20
- 229910021389 graphene Inorganic materials 0.000 claims description 19
- 239000008367 deionised water Substances 0.000 claims description 18
- 229910021641 deionized water Inorganic materials 0.000 claims description 18
- 239000002041 carbon nanotube Substances 0.000 claims description 16
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
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- 229910010271 silicon carbide Inorganic materials 0.000 claims description 9
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 8
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 8
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- 229910052581 Si3N4 Inorganic materials 0.000 claims description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 7
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 6
- 239000006230 acetylene black Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
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- 229920002125 Sokalan® Polymers 0.000 claims description 5
- 230000002457 bidirectional effect Effects 0.000 claims description 5
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 3
- -1 Polytetrafluoroethylene Polymers 0.000 claims description 3
- 238000013019 agitation Methods 0.000 claims description 3
- 239000003273 ketjen black Substances 0.000 claims description 3
- 239000002116 nanohorn Substances 0.000 claims description 3
- 239000000661 sodium alginate Substances 0.000 claims description 3
- 235000010413 sodium alginate Nutrition 0.000 claims description 3
- 229940005550 sodium alginate Drugs 0.000 claims description 3
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical group [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 2
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 2
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 2
- 150000001722 carbon compounds Chemical class 0.000 claims 5
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- 239000000126 substance Substances 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 3
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- 230000008569 process Effects 0.000 description 38
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 25
- 230000000694 effects Effects 0.000 description 21
- 229910002804 graphite Inorganic materials 0.000 description 19
- 239000010439 graphite Substances 0.000 description 19
- 238000004080 punching Methods 0.000 description 18
- 239000002245 particle Substances 0.000 description 15
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 14
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 13
- 239000002131 composite material Substances 0.000 description 10
- 238000001035 drying Methods 0.000 description 9
- 230000001502 supplementing effect Effects 0.000 description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 239000003792 electrolyte Substances 0.000 description 8
- 229910052744 lithium Inorganic materials 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- QMGYPNKICQJHLN-UHFFFAOYSA-M Carboxymethylcellulose cellulose carboxymethyl ether Chemical compound [Na+].CC([O-])=O.OCC(O)C(O)C(O)C(O)C=O QMGYPNKICQJHLN-UHFFFAOYSA-M 0.000 description 7
- 239000013530 defoamer Substances 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 6
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 6
- 239000002174 Styrene-butadiene Substances 0.000 description 5
- 238000009775 high-speed stirring Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000011049 filling Methods 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 238000004062 sedimentation Methods 0.000 description 3
- 241000282320 Panthera leo Species 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000006257 cathode slurry Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000004584 polyacrylic acid Substances 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 238000009849 vacuum degassing Methods 0.000 description 2
- 241000872198 Serjania polyphylla Species 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000002003 electrode paste Substances 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
Classifications
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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
- H01M4/04—Processes of manufacture in general
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/80—Mixing plants; Combinations of mixers
- B01F33/83—Mixing plants specially adapted for mixing in combination with disintegrating operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/80—Mixing plants; Combinations of mixers
- B01F33/836—Mixing plants; Combinations of mixers combining mixing with other treatments
- B01F33/8361—Mixing plants; Combinations of mixers combining mixing with other treatments with disintegrating
- B01F33/83613—Mixing plants; Combinations of mixers combining mixing with other treatments with disintegrating by grinding or milling
-
- 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
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
-
- 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
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a kind of preparation methods of negative electrode of lithium ion battery electrocondution slurry, this method includes that the material for forming electrode slurry is put into ball grinder to mix, the material of the composition electrode slurry contains active material, conductive agent, binder and solvent, the mixing is included in the ball grinder to the active material and solvent needed for dissolving the active material carries out the first homogenate and stirs, and obtains and disperses uniform mixed slurry；The conductive agent and the binder are added into the mixed slurry, and the solvent is supplied according to required solid content, carries out the second homogenate stirring, obtains the electrocondution slurry；Wherein, the revolving speed of the first homogenate stirring is higher than the second homogenate stirring.Preparation method rational technology design to filler and is closed slurry mode and is improved the characteristics of for different material respectively, closes slurry efficiency to be promoted, shortens and close slurry duration, enhancing electrocondution slurry chemical property.
Description
Technical Field
The invention relates to the technical field of lithium ion battery material manufacturing, in particular to a preparation method of lithium ion battery cathode conductive slurry.
Background
The lithium ion battery system is widely applied to the fields of new energy automobiles, portable electronic products, solar photovoltaic and wind power generation energy storage systems and the like in recent years, and has the characteristics of high energy density, high working voltage, stable cycle performance, good load characteristic, high charge and discharge rate, safety and no pollution compared with the traditional nickel-hydrogen and nickel-cadmium battery systems.
In each component of the lithium ion battery, the electrochemical characteristics of the electrode material determine the upper limit of the energy density of the system, but the processes of slurry preparation, battery assembly and the like play a key role in the exertion of the electrochemical performance. The slurry mixing process plays an important role in the production of lithium ion batteries, because when the electrode plate is manufactured, the components are fully mixed to prepare electrode slurry, the electrode slurry is coated on a current collector by adopting a wet film preparation method, and the electrode plate can be obtained by punching the obtained dry film through punching equipment through drying, dewatering and deoxidizing processes. Therefore, the performance of the electrode sheet is directly affected by the quality of the electrode slurry preparation. The preparation process of the slurry is actually a multi-component solid-liquid mixing process, so if excellent conductive slurry needs to be prepared, the problem which needs to be directly solved is that all components are fully mixed in the slurry mixing process, and the agglomeration is avoided. The prior art has disclosed that the mixing of the electrode slurry by the ball milling tank can further break and refine the material, thereby shortening the slurry mixing time and improving the cycle performance of the battery. However, in the process, all the materials forming the electrode slurry are added into the ball milling tank at one time for slurry mixing, which still cannot meet the industrial requirements to a certain extent, and the problems of long slurry mixing time, poor slurry mixing effect and poor battery circulation stability exist.
Disclosure of Invention
The embodiment of the invention provides a preparation method of lithium ion battery cathode conductive paste, which aims to solve the problems of long paste mixing time, poor paste mixing effect and poor battery cycle stability in the prior art. The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of such embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
The invention aims to provide a preparation method of lithium ion battery negative electrode conductive slurry.
In some exemplary embodiments, the preparation method of the lithium ion battery negative electrode conductive paste specifically includes: putting materials for forming electrode slurry into a ball milling tank for mixing, wherein the materials for forming the electrode slurry contain active substances, conductive agents, binders and solvents, and the mixing comprises the steps of performing first homogenate stirring on the active substances and the solvents required for dissolving the active substances in the ball milling tank to obtain uniformly dispersed mixed slurry; adding the conductive agent and the binder into the mixed slurry, complementing the solvent according to the required solid content, and performing second homogenizing and stirring to obtain the conductive slurry; wherein the first homogenizing mixer is stirred at a higher speed than the second homogenizing mixer.
The filler and close thick liquid mode of this embodiment are different with prior art, prior art is that all materials that will prepare conductive paste put into ball-milling jar simultaneously and grind until thick liquids dispersion is even, such mixed mode is comparatively simple, do not pack according to the characteristics of different materials, it is inhomogeneous easily to appear the inside misce bene of thick liquids, local many tiny particles take place to reunite and produce "ash cake", "ash ball", "ash bag" of similar secondary particle, and then influence subsequent mixed effect, finally lead to closing thick liquid inefficiency, it is long to close thick liquid time, a series of problems such as thick liquids effect difference. In order to solve the problems, the filling and pulp mixing modes are improved. Firstly, changing 'one-step' filling into two steps, firstly, uniformly dispersing active substances, secondly, adding a conductive agent and a binder into the uniformly dispersed mixed slurry containing the active substances, and mixing for the second time until all the materials are uniformly dispersed. In the conductive slurry, the proportion of active substances is high, and the active substances are difficult to disperse, so that high-speed stirring is required in the first homogenizing and stirring stage to fully disperse the active substances, and stable and uniform mixed slurry is obtained; the second step is to add the conductive agent and the binder because the ratio of the addition amount of the conductive agent to the total solid addition amount is low and the absolute amount is small, and the effect of full mixing can be achieved without high rotating speed during mixing. Some highly effective commercially available novel conductive agents exist in the form of a slurry or dispersion, which is much easier in mixing and dispersing than ordinary powders or granules. The binder is basically in the form of solution or glue solution, because the liquid-liquid mixing is easy and sufficient, and the requirement can be met at low rotating speed. Considering that the addition amount of solids is small in the stage, and the caking property is easily broken by demulsification of the caking agent at high rotating speed, the low-rotating-speed stirring is adopted, so that the demulsification is prevented, the caking effect of the caking agent is ensured, and the components are further dispersed to obtain the target product, namely the conductive paste. The slurry has good dispersibility, and the coated pole piece has uniform thickness. The method can effectively improve the slurry mixing efficiency, reduce the slurry mixing time and improve the electrical property of the slurry. The method has universality, and is not only suitable for aqueous negative electrode conductive slurry systems, but also suitable for slurry systems of oily systems and positive electrode materials. And the process is easy to amplify, and the capacity of preparing the slurry once is greatly improved.
In some optional embodiments, in order to further enhance the slurry mixing efficiency and the electrochemical performance of the slurry, the slurry mixing mode may be further optimized, such as the stirring mode of the first homogenate stirring and/or the second homogenate stirring is a bidirectional stirring mode with alternating positive and negative rotation. In this embodiment, the slurry is stirred and mixed by adopting a forward-reverse rotation alternate S-shaped stirring mode, the traditional one-way stirring process is replaced, the liquid in the ball milling tank generates a vortex in the forward-reverse rotation alternate stirring process, the solid-liquid contact is strengthened, a more sufficient dispersion effect than that of the traditional single forward rotation or reverse rotation stirring mode can be obtained, the sedimentation problem of the slurry is effectively improved, the slurry mixing time of each step is further reduced, and the stirring and crushing effects of the ball milling tank are enhanced.
The planetary ball mill has two rotational speeds: rotation and revolution. Since the planetary motion is adopted, the ratio between the rotation speed and the revolution speed is fixed. The rotational speed indicated by the planetary ball mill is the rotational speed of the grinding pot. In the above-described embodiment, if a planetary ball mill is used, the "S" type stirring pattern in which forward rotation and reverse rotation are alternated means bidirectional self-rotation stirring in which the ball mill pot is rotated in forward and reverse directions alternately.
The thickener is a commonly used substance for adjusting the viscosity of the conductive paste, and in some alternative embodiments, if the material constituting the electrode paste contains the thickener, the thickener can be used in two steps and added to the conductive paste in two stirring steps as described in the above embodiments, in order to further enhance the paste mixing efficiency and the electrochemical performance of the paste. In the first homogenizing and stirring process, the thickener is added to provide a solution system with a primary proper viscosity, so that solid-liquid combination is more compact and mixing is more sufficient; during the second homogenizing and stirring process, the thickener is added to adjust the viscosity of the system to the required viscosity, and the thickener is added to improve the binding force between the binder and the particles and enhance the binding effect. If the required total amount of the thickening agent is added in one step, the whole solution system is excessively viscous, the stirring is difficult to be fully performed, and the local part is easy to form agglomeration, so that the dispersing effect is influenced. While at the same time not facilitating the adhesion of the binder to the particles.
In the preparation process of the conductive paste, especially in the preparation process of the aqueous conductive paste, a large amount of bubbles are generated during stirring of the viscous paste and are difficult to remove, so that the paste mixing efficiency is reduced, the paste mixing time is prolonged, the prepared dry pole piece can be remarkably wrinkled and cracked, the coating thickness is not uniform, the quality and the load uniformity of the pole piece are not fully ensured, the electrochemical performance of the pole piece cannot be fully exerted, the repeatability is obviously influenced, and the defoaming is a problem to be solved in the preparation process of the conductive paste.
In some optional embodiments, in order to enhance the slurry mixing efficiency, shorten the slurry mixing time and enhance the electrochemical performance of the slurry, the defoaming agent is introduced into the material to remove air bubbles in the slurry.
Furthermore, the defoaming agent is stirred and added into the conductive slurry through the first homogenate, so that the defoaming purpose can be effectively achieved. Since the first homogenizing and stirring is a high-speed stirring process and in addition, the active substance, the thickener and the solvent generate a large amount of bubbles during the stirring process, the most effective defoaming means is to add the defoaming agent at the first homogenizing and stirring stage. It is of course possible to add a suitable amount of defoamer during the stirring of the second homogenate to achieve the purpose of defoaming further.
Further, after the second homogenizing and stirring process is completed, defoaming treatment is performed on the conductive slurry, for example, the slurry is placed in a vacuum defoaming box to remove bubbles again. Further, the defoaming treatment process specifically comprises the following steps: keeping the vacuum degree at-0.1 MPa for 10-15 min.
In some optional embodiments, if the lithium ion battery negative electrode conductive paste is an aqueous paste, that is, the solvent is deionized water, the active material may be one or more of a silicon/carbon composite, a silicon oxide/carbon composite, a silicon/silicon nitride/carbon composite, a silicon/silicon oxide/carbon composite, and a silicon/silicon carbide/carbon composite. The thickening agent is sodium carboxymethyl Cellulose (CMC). In the embodiment, CMC is used as a thickening agent, on one hand, the total addition of the adhesive is reduced while the circulation stability is ensured by matching with other water-soluble adhesives, and the overall energy density of the battery is improved; on the other hand, the viscosity of the slurry is adjusted, and the adhesion effect of the adhesive is improved to strengthen the adhesion effect. The combination of various water-based bonding systems and CMC has good bonding effect while reducing the total addition amount. Further improve the slurry mixing efficiency, shorten the slurry mixing time and improve the electrochemical performance of the conductive slurry.
Preferably, the conductive agent is: super P Li, Super S, 350G, acetylene black, Ketjen black Carbon ECP600JD, KS-6, KS-15, SFG-6, SFG-15, Vapor Grown Carbon Fiber (VGCF), Carbon Nanotube (CNT), Carbon Nanohorn (CNH), Mesoporous Graphene (MGF), Carbon Nanotube-graphene hybrid, Carbon Nanotube aqueous slurry, graphene aqueous slurry, Carbon Nanotube-graphene aqueous slurry hybrid.
Preferably, the binder is: one or more of Polyacrylic acid (PAA), Polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), sodium alginate sodium silicate (Alg), Styrene Butadiene Rubber (SBR), LA132, LA133N, LA134, LA135, LA136D, and ME 1209.
Preferably, the defoaming agent is: one or more of Ethylene Carbonate (EC), Propylene Carbonate (PC), ethanol, and isopropanol
The above embodiment provides a preferable process of materials, namely, the active material, the thickener, the conductive agent, the binder and the defoaming agent, in the aqueous lithium ion negative electrode conductive slurry, CMC is added in the process, so that the use of the binder is reduced, and the above mentioned binder is likely to generate emulsion breaking in the second homogenizing and stirring process to affect the slurry mixing effect, so that the slurry mixing efficiency can be further improved, the slurry mixing time can be reduced, and the electrochemical performance of the conductive slurry can be enhanced through the preferable process.
Further, the solid content is 5-30% by taking the mass of the conductive paste as 100%; the solid content includes the thickener, a binder, the conductive agent, the antifoaming agent, and the active material; wherein the thickener is: the adhesive is as follows: the conductive agent: the defoaming agent comprises the following components: the mass ratio of the active substances is 0.1-2.0%: 0.5-15%: 0.5-15%: 0.1-5%: 70-97.5%. Preferably, the viscosity of the conductive paste ranges from 2000 to 5000 mPa.s. The preferred proportion of each component in the material, the solid content of the conductive slurry and the viscosity range are given in the above embodiment, and under the guidance, the lithium ion battery negative electrode conductive slurry with excellent electrochemical performance can be prepared more efficiently.
In some alternative embodiments, before the first homogenate is agitated, the method further comprises the step of preparing a thickener solution, specifically: mixing CMC and deionized water until the whole is clear and transparent, wherein the mass ratio of the CMC to the deionized water is 0.5-2%: 98-99.5%.
Further, the use mode of the thickening agent is specifically as follows: 60-80% of the total amount of the thickener solution added during the first homogenizing and stirring, and the rest of the thickener solution is added into the conductive paste through the second homogenizing and stirring. In this example, the CMC was not dispersed directly in the slurry as a powder, but was pre-dispersed, i.e., prepared as a thickener solution. The embodiment can further enhance the slurry mixing efficiency, reduce the slurry mixing time and enhance the electrochemical performance of the conductive slurry.
The above examples have disclosed the production process, components and their proportions for preparing the aqueous lithium ion battery negative electrode slurry, and the stirring manner is further described below:
in some optional embodiments, the rotation speed of the first homogenizing and stirring is 300-600 r/min, and the rotation speed of the second homogenizing and stirring is 10-120 r/min; and the first homogenate stirring and the second homogenate stirring both adopt the bidirectional stirring mode of alternating forward rotation and reverse rotation. The rotational speed of twice homogenate stirring has further been injectd to this embodiment, and the rotational speed of first homogenate stirring is less than 300r/min, and it is low to close thick liquid efficiency, and dispersion effect is poor, and it is too fast that its rotational speed is higher than 600r/min then the generating speed of bubble, is difficult to the defoaming, and then leads to closing thick liquid inefficiency, and dispersion effect is poor. The rotating speed of the second homogenate stirring is lower than that of the first homogenate stirring, the purpose of the second homogenate stirring is to disperse the conductive agent and the binder, and the rotating speed of the second homogenate stirring needs to be limited within 120r/min because the binder can be demulsified under the condition of high-speed stirring and further influences the slurry combination effect. In the embodiment, the rotating speed range of the two-step homogenizing and stirring is disclosed, so that the slurry mixing efficiency is improved, the total slurry mixing duration is reduced, and the electrochemical performance of the conductive slurry is enhanced.
Further, in the first homogenizing and stirring process, the time of single forward rotation or single reverse rotation is 5-15 min, and the total stirring time is 0.5-2 h. In the second homogenate stirring process, the time of single forward rotation or reverse rotation is 5-15 min, and the total stirring time is 0.5-2 h. This example shows the optimum stirring manner and stirring time of the above component slurry during the above preparation process.
Preferably, during the homogenizing and stirring process, namely during the stirring process of the first homogenate and the stirring process of the second homogenate, the temperature of the slurry needs to be controlled to be between 20 ℃ and 40 ℃ so as to avoid the influence on the stability of each component in the slurry due to a large amount of heat energy generated during the stirring and ball milling process, and the casualties and equipment loss caused by heat generation. The slurry temperature can be controlled by a thermostat in the ball mill.
In some optional embodiments, the ball mill described in each of the above embodiments is a planetary ball mill, such as a single planetary ball mill, an all-round planetary ball mill, a horizontal planetary ball mill, a variable temperature planetary ball mill, a double planetary ball mill, an ultrasonic planetary ball mill, a liquid nitrogen type planetary ball mill, a novel semicircular planetary ball mill, and the like.
In some optional embodiments, the preparation steps of the lithium ion battery negative electrode conductive paste are specifically as follows:
1) preparation of a thickener solution: mixing a thickening agent with a certain molecular weight, such as CMC, with deionized water according to a certain proportion, stirring and dissolving uniformly by using a water bath until the whole is clear and transparent, and taking out for later use;
2) high-speed homogenizing and stirring: mixing an active substance and a defoaming agent, adding 60-80% of the total demand of a thickening agent solution, adding 60-80% of the total demand of a solvent into a ball milling tank, setting the stirring speed to be 300-600 r/min, and performing forward rotation and reverse rotation alternately in a stirring mode, wherein the forward rotation and reverse rotation are performed for 5-15 min each time, the total stirring time is 0.5-2 h, and the temperature of the slurry is controlled to be 20-40 ℃;
3) low-speed homogenizing and stirring: mixing conductive agent powder and a binder, supplementing required solvent and thickener into a ball milling tank, adjusting to required solid content and viscosity, setting the stirring speed to be 10-120 r/min, and performing forward and reverse stirring-alternation in a stirring mode, wherein each forward (reverse) rotation single time is 5-15 min, the total stirring time is 0.5-2 h, and the temperature of the slurry is controlled to be 20-40 ℃;
4) defoaming treatment: the obtained slurry enters a vacuum defoaming box to remove bubbles again, and the vacuum degree is kept at-0.1 MPa for 10-15min, thus obtaining the lithium ion battery cathode slurry prepared by the method;
wherein, the active substances in the step (1) are: one or more of a silicon/carbon composite, a silicon oxide/carbon composite, a silicon/silicon nitride/carbon composite, a silicon/silicon oxide/carbon composite, and a silicon/silicon carbide/carbon composite; the defoaming agent in the step (2) is: one or more of Ethylene Carbonate (EC), Propylene Carbonate (PC), ethanol and isopropanol; the conductive agent in the step (3) is: one or more of Super P Li, Super S, 350G, acetylene black, Ketjen black carbon ECP600JD, KS-6, KS-15, SFG-6, SFG-15, vapor grown carbon fiber VGCF, carbon nanotube CNT, carbon nanohorn CNH, mesoporous graphene MGF, carbon nanotube-graphene hybrid, carbon nanotube aqueous slurry, graphene aqueous slurry, and carbon nanotube-graphene hybrid aqueous slurry; the binder in the step (3) is: one or more of polyacrylic acid (PAA), Polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), sodium alginate (Alg), Styrene Butadiene Rubber (SBR), LA132, LA133N, LA134, LA135, LA136D and ME 1209; the solvent in the step (2) and (3) is: deionized water; in the thickener solution described in step (1), the thickener CMC: solvent (deionized water) ═ 0.5 to 2%: 98-99.5%; in the steps (2) and (3), the solid content of the substances is 5-30% and the viscosity is 2000-5000 mPa.s, wherein the mass of the conductive slurry is 100%; the solid content includes the thickener, a binder, the conductive agent, the antifoaming agent, and the active material; wherein the thickener is: the adhesive is as follows: the conductive agent: the defoaming agent comprises the following components: the mass ratio of the active substances is 0.1-2.0%: 0.5-15%: 0.5-15%: 0.1-5%: 70-97.5%.
Compared with the prior art, the invention has the following advantages and improvement effects:
① the process is reasonably designed, abandons the mode of grinding all materials of the conductive paste in the traditional production process at the same time, and improves the filling and paste combining modes respectively according to the characteristics of different materials so as to improve the paste combining efficiency, shorten the paste combining time and enhance the electrochemical performance of the conductive paste.
② on the basis of mixing slurry by using a ball mill, the slurry is mixed by adopting a positive-reverse rotation alternative S-shaped stirring mode, the traditional one-way stirring process is replaced, the solid-liquid contact is strengthened, the dispersion effect is improved, the sedimentation problem of the slurry is improved, the slurry mixing efficiency is further improved, the slurry mixing time is reduced, and the electrochemical performance of the conductive slurry is enhanced.
③ the preparation method has universality, is not only suitable for the preparation of aqueous cathode conductive slurry, but also suitable for the preparation of other systems such as slurry of oily and anode materials.
④ the process is easy to be enlarged, and the capability of preparing slurry in one time is greatly improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
FIG. 1 is a graph comparing the cycle performance of example 1 with that of comparative example 1.
Fig. 2 is a graph comparing coulombic efficiencies of example 1 and comparative example 1.
Detailed Description
The invention is further illustrated by the following specific examples.
Some of the reagents used in the following examples are illustrated:
adhesive: LA132, LA133N, LA134, LA135, LA136D, and ME1209 were purchased from atlanta city, university, francisco, inc.
Conductive agent: super P Li, Super S, 350G, KS-6, KS-15, SFG-6, SFG-15 were all purchased from Switzerland Gaoka; acetylene black was purchased from Tianjin chemical hundred million borrelium; ketjen ECP, ketjen ECP600JD are available from japan LION king LION; the carbon nanotube aqueous slurry, the graphene aqueous slurry and the carbon nanotube-graphene hybrid aqueous slurry are purchased from Jiangsu Tiannai science and technology GmbH.
Planetary ball mill: the single planetary ball mill QXQM-20, the double planetary ball mill SXQM-6, and the liquid nitrogen type planetary ball mill YD-QMQX-4L were purchased from Nanjing university instruments.
Example 1:
at normal temperature, mixing a thickening agent of carboxymethyl cellulose (CMC) powder with ultrapure deionized water in a mass ratio of 2: 98, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active material micron-sized silicon oxide/graphite (SiO)x87.2% of C: 12.8%): conductive agent carbon nanotube aqueous slurry LB-260: conductive agent graphene aqueous slurry LB2G 3: SBR as a binder: defoamer EC 5%: 85%: 2%: 2%: 5%: 1% of each component is added. Firstly, mixing micron-sized silicon oxide/graphite serving as an active substance with an antifoaming agent EC, adding 70% of the total demand of a thickening agent CMC solution, adding 70% of the total demand of a solvent into a ball milling tank, stirring by adopting a single-row star-type ball mill, setting the stirring speed to be 600r/min, carrying out forward rotation for 5min, then carrying out reverse rotation for 5min, carrying out total stirring for 0.5h, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing conductive agent carbon nanotube aqueous slurry LB-260 and graphene aqueous slurry LB2G3 with binder SBR, adding into a ball milling tank, supplementing the required solvent and thickening agent, adjusting until the solid content is 10% and the viscosity is 2200mPa.s, setting the stirring speed to 120r/min, carrying out forward rotation for 5min, then carrying out reverse rotation for 5min, carrying out total stirring for 0.5h, controlling the temperature of the slurry to be about 30 ℃, removing bubbles in the obtained slurry in a vacuum defoaming box again, and keeping the vacuum degree of-0.1 MPa for 10min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Comparative example 1:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 2: 98, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active material micron-sized silicon oxide/graphite (SiO)x87.2% of C: 12.8%): conductive agent carbon nanotube aqueous slurry LB-260: conductive agent graphene aqueous slurry LB2G 3: SBR as a binder: defoamer EC 5%: 85%: 2%: 2%: 5%: 1% of each component is added. Firstly, mixing micron-sized silicon oxide/graphite serving as an active substance with an antifoaming agent EC, adding 70% of the total demand of a thickening agent CMC solution, adding 70% of the total demand of a solvent into a ball milling tank, stirring by adopting a single-row star-type ball mill at a stirring speed of 600r/min for 0.5h in a forward rotation manner, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing conductive agent carbon nanotube aqueous slurry LB-260 and graphene aqueous slurry LB2G3 with binder SBR, adding into a ball milling tank, supplementing the required solvent and thickening agent, adjusting until the solid content is 10% and the viscosity is 2200mPa.s, setting the stirring speed to 120r/min, positively rotating and stirring for 0.5h, simultaneously controlling the temperature of the slurry to be about 30 ℃, removing bubbles in the obtained slurry in a vacuum defoaming box again, and keeping the vacuum degree of-0.1 MPa for 10min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior. Electrochemical performance tests were performed on the lithium ion button half cells prepared in example 1 and comparative example 1, and the results of comparing the charge and discharge cycle performance at 1A/g are shown in FIG. 1.
Comparative example 2:
mixing the thickening agent CMC powder with the super-high-temperature-resistant agentPure deionized water in a mass ratio of 2: 98, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active material micron-sized silicon oxide/graphite (SiO)x87.2% of C: 12.8%): conductive agent carbon nanotube aqueous slurry LB-260: conductive agent graphene aqueous slurry LB2G 3: SBR as a binder: defoamer EC 5%: 85%: 2%: 2%: 5%: 1% of each component is added. After adding the components, supplementing required amount of solvent ultrapure deionized water, adjusting the solid content to 10% and the viscosity to 2200mPa.s, stirring by using a single-row star-type ball mill, setting the stirring speed at 600r/min, carrying out forward rotation for 5min, then carrying out reverse rotation for 5min, carrying out high-speed stirring for 0.5h, and simultaneously controlling the temperature of the slurry to be about 30 ℃. And setting the stirring speed to be 120r/min, carrying out forward rotation for 5min, continuing to carry out reverse rotation for 5min, stirring and dispersing for 0.5h, controlling the temperature of the slurry to be about 30 ℃, removing bubbles in the obtained slurry again in a vacuum degassing box, and keeping the vacuum degree at-0.1 MPa for 10min to obtain the cathode water-based slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Example 2:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 2: 98, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active material micron-sized silicon/silicon carbide/graphite (Si: SiC: C72%: 21%: 7%): conductive agent SPG-6: adhesive LA 132: defoamer PC ═ 0.5%: 52%: 40%: 3.5%: 3%: 1% of each component is added. Firstly, mixing active material micron-sized silicon/silicon carbide/graphite with defoaming agent PC, adding 60% of the total demand of thickening agent CMC solution, adding 65% of the total demand of solvent into a ball milling tank, stirring by adopting a double-planet ball mill, setting the stirring speed to be 480r/min, carrying out forward rotation for 15min, then carrying out reverse rotation for 15min, carrying out total stirring for 2h, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing a conductive agent SPG-6 and a binder LA132, adding the mixture into a ball milling tank, supplementing the required solvent and thickener, adjusting the solid content to be 15% and the viscosity to be 2600mPa.s, setting the stirring speed to be 60r/min, carrying out forward rotation for 10min, then carrying out reverse rotation for 10min, carrying out total stirring for 1h, controlling the temperature of the slurry to be about 30 ℃, removing bubbles in the obtained slurry in a vacuum defoaming box again, and keeping the vacuum degree to be-0.1 MPa for 15min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Example 3:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 1.5: 98.5, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active material micron-sized silicon/graphite (Si: C15%: 85%): conductive agent VGCF: super P Li: binder PAA: 1% of defoaming agent ethanol: 80%: 1.5%: 10%: 6%: 1.5% of each ingredient was added. Firstly, mixing micron-sized silicon/graphite serving as an active substance with defoaming agent ethanol, adding 80% of the total demand of a thickening agent CMC solution, adding 75% of the total demand of a solvent into a ball milling tank, stirring by adopting a double-planet type ball mill, setting the stirring speed to be 300r/min, carrying out forward rotation for 10min, then carrying out reverse rotation for 5min, carrying out total stirring for 0.5h, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing and adding a conductive agent VGCF, a Super P Li and a binder PAA into a ball milling tank, supplementing the required solvent and a thickening agent to adjust the solid content to be 5% and the viscosity to be 2000mPa.s, setting the stirring speed to be 10r/min, carrying out forward rotation for 10min, then carrying out reverse rotation for 10min, carrying out total stirring for 2h, controlling the temperature of the slurry to be about 30 ℃, removing bubbles in the obtained slurry in a vacuum defoaming box again, and keeping the vacuum degree to be-0.1 MPa for 12min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Example 4:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 0.5: 99.5, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: active thickener CMC: active material micron-sized silicon/silicon oxide/graphite (Si: SiO)xC is 70%: 21%: 9 percent of: micron-sized silicon/silicon carbide/graphite (Si: SiC: C: 72%: 21%: 7%): conductive agent VGCF: SPG-15: adhesive LA 133N: defoaming agent EC 1%: 45%: 48%: 1.5%: 1%: 3%: 0.5% of each ingredient was added. Firstly, mixing active substances of micron-sized silicon/silicon oxide/graphite and micron-sized silicon/silicon carbide/graphite with an antifoaming agent EC, adding 60 percent of the total demand of a thickening agent CMC solution, adding 70 percent of the total demand of a solvent into a ball-milling tank, stirring by adopting a liquid nitrogen planetary ball mill, setting the stirring speed to be 420r/min, and rotating forward for a single time of 5And (5) continuously reversing for 10min for a single time, wherein the total stirring time is 1.25h, and the temperature of the slurry is controlled to be about 30 ℃. Mixing and adding conductive agents VGCF and SPG-15 and a binder LA133N into a ball milling tank, supplementing the required solvent and thickener to adjust the solid content to 25% and the viscosity to 2800mPa.s, setting the stirring speed to 96r/min, setting the forward rotation single time to 10min and the reverse rotation single time to 15min, stirring the slurry for 1.75h, controlling the temperature of the slurry to be about 30 ℃, removing bubbles from the obtained slurry in a vacuum degassing box again, and keeping the vacuum degree to-0.1 MPa for 15min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Example 5:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 1.5: 98.5, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: nanoscale silicon/silicon nitride/graphite (Si: Si)3N4C is 64.6%: 23.5%: 11.9%): conductive agent CNH: acetylene black: binder ME 1209: defoaming agent EC 1%: 90%: 0.5%: 3.5%: 2.5%: 2.5% of each ingredient. Firstly, mixing an active substance nano-scale silicon/silicon nitride/graphite with an antifoaming agent EC, adding 75% of the total demand of a thickening agent CMC solution, adding 65% of the total demand of a solvent into a ball milling tank, stirring by adopting a liquid nitrogen type planetary ball mill, setting the stirring speed to be 540r/min, carrying out forward rotation for 15min, then carrying out reverse rotation for 15min, carrying out total stirring for 1h, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing conductive agent CNH and acetylene black with binder ME1209, adding into ball milling tank, andand (3) supplementing the required solvent and thickener, adjusting to 20% of solid content and 2600mPa.s, setting the stirring speed to 120r/min, continuing to rotate reversely for 10min after rotating forward for 5min, and controlling the temperature of the slurry to be about 30 ℃ at the same time, introducing the obtained slurry into a vacuum defoaming box to remove bubbles again, and keeping the vacuum degree of-0.1 MPa for 10min to obtain the cathode aqueous slurry. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
Example 6:
at normal temperature, mixing a thickening agent CMC powder with ultrapure deionized water in a mass ratio of 1: 99, and stirring and dissolving the mixture evenly in water bath at 30 ℃ until the whole mixture is clear and transparent to obtain a transparent viscous colloidal solution. Thickening agent CMC according to the mass ratio: micron-sized silicon monoxide/graphite (SiO)x87.2% of C: 12.8%): nanoscale silicon/silicon nitride/graphite (Si: Si)3N4C is 64.6%: 23.5%: 11.9%): conductive agent CNT: MGF: binder PTFE: defoamer isopropanol is 1%: 50%: 30%: 2%: 2%: 13%: 2% of each component is added. Firstly, mixing active substances of micron-sized silicon monoxide/graphite and nano-sized silicon/silicon nitride/graphite with defoaming agent isopropanol, adding 70% of the total demand of a thickening agent CMC solution, adding 70% of the total demand of a solvent into a ball milling tank, stirring by adopting a liquid nitrogen type planetary ball mill, setting the stirring speed to be 360r/min, carrying out forward rotation for 10min, then carrying out reverse rotation for 10min, carrying out total stirring for 2h, and simultaneously controlling the temperature of slurry to be about 30 ℃. Mixing conductive agents CNT and MGF and a binder PTFE, adding the mixture into a ball milling tank, supplementing the required solvent and thickening agent to adjust the solid content to 30 percent and the viscosity to 4500mPa.s, and stirringThe stirring speed is set to be 120r/min, the forward rotation single time is 15min, the reverse rotation single time is 15min, the total stirring time is 2h, the temperature of the slurry is controlled to be about 30 ℃, the obtained slurry enters a vacuum defoaming box to remove bubbles again, the vacuum degree is-0.1 MPa, and the slurry is kept for 15min, so that the cathode water-based slurry is obtained. And measuring the size of particles in the slurry by using a scraper fineness meter after the preparation is finished. According to the conventional production process of the lithium ion button cell, aqueous negative electrode slurry is coated on a current collector by a wet film preparation method, and a negative electrode plate can be obtained by punching a dry film through punching equipment through drying and dehydrating and deoxidizing processes. And assembling the button half cell with a metal lithium sheet, a diaphragm, electrolyte, a positive and negative electrode shell, a spring sheet and a gasket in a glove box, and standing for 12 hours to obtain the lithium ion button half cell with fully soaked interior.
The following table shows the electrochemical performance test results for each example and comparative example:
TABLE 1 cycle performance test
TABLE 2 evaluation of particle size in slurries after agitation
| Item | Stirring mode | Feeding mode | D50/μm |
| Example 1 | Forward-reverse rotation | Adding in twice | 6 |
| Comparative example 1 | Forward rotation | Adding in twice | 12 |
| Comparative example 2 | Forward-reverse rotation | Is added at one time | 25 |
| Example 2 | Forward-reverse rotation | Adding in twice | 3 |
| Example 3 | Forward-reverse rotation | Adding in twice | 5 |
| Example 4 | Forward-reverse rotation | Adding in twice | 6 |
| Example 5 | Forward-reverse rotation | Adding in twice | 8 |
| Example 6 | Forward-reverse rotation | Adding in twice | 2 |
D50 in table 2 is also called median or median particle size, which is a typical value representing the size of the particle size, which accurately divides the population into two equal parts, i.e. 50% of the particles exceed this value and 50% are below this value.
According to the data in the two tables, the lithium ion battery cathode slurry prepared by the slurry preparation method provided by the invention has excellent capacity retention rate in a long-cycle process, and can obtain higher first effect while having long service life. And simultaneously, more sufficient mixing and dispersing effects can be obtained.
To sum up:
the preparation method of the high-performance negative electrode conductive paste for the lithium ion battery, provided by the invention, aims at the problems of low efficiency, large energy consumption, multiple steps, long time consumption and the like of the traditional paste preparation technology, and realizes the aims of fully mixing and dispersing a multi-component paste system in a short time, improving the preparation efficiency, shortening the preparation steps, saving the energy consumption and the like, and meanwhile, the high-performance conductive paste with good uniformity and no sedimentation is prepared, the electrode plate made of the paste has excellent electrochemical performance, and the cycle stability is improved with high efficiency. Meanwhile, the process is easy to amplify, the preparation capacity of single slurry is greatly improved, the preparation process is universal, and the method is also suitable for preparation of other oily systems and anode material slurry.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention, and not all the changes and modifications of the above embodiments are within the scope of the present invention.
Claims (10)
1. A preparation method of lithium ion battery negative electrode conductive slurry comprises the steps of putting materials for forming electrode slurry into a ball milling tank for mixing, wherein the materials for forming the electrode slurry contain active substances, conductive agents, binders and solvents, and is characterized in that the mixing comprises the steps of carrying out first homogenizing and stirring on the active substances and the solvents required for dissolving the active substances in the ball milling tank to obtain uniformly dispersed mixed slurry; adding the conductive agent and the binder into the mixed slurry, complementing the solvent according to the required solid content, and performing second homogenizing and stirring to obtain the conductive slurry; wherein the first homogenizing agitation is at a higher speed than the second homogenizing agitation.
2. The method of claim 1, wherein the stirring pattern of the first homogenizing stirring and/or the second homogenizing stirring is bidirectional stirring with alternating forward and reverse rotation.
3. The method of claim 2, wherein the material constituting the electrode slurry contains a thickener; the thickening agent is used in two steps, namely a first part thickening agent and a second part thickening agent, wherein the first part thickening agent is added into the conductive slurry through the first homogenate under stirring, and the second part thickening agent is added into the conductive slurry through the second homogenate under stirring.
4. The production method according to claim 3, wherein the material constituting the electrode slurry contains an antifoaming agent; the antifoaming agent is added to the conductive paste by stirring the first homogenate.
5. The method of claim 3, wherein the solvent is deionized water; the active substance is one or more of silicon/carbon compound, silicon oxide/carbon compound, silicon/silicon nitride/carbon compound, silicon/silicon oxide/carbon compound and silicon/silicon carbide/carbon compound; the thickening agent is sodium carboxymethyl cellulose CMC.
6. The method of claim 5, wherein the conductive agent is: one or more of Super P Li, Super S, 350G, acetylene black, Ketjen black carbon ECP600JD, KS-6, KS-15, SFG-6, SFG-15, vapor grown carbon fiber VGCF, carbon nanotube CNT, carbon nanohorn CNH, mesoporous graphene MGF, carbon nanotube-graphene hybrid, carbon nanotube aqueous slurry, graphene aqueous slurry, and carbon nanotube-graphene hybrid aqueous slurry; and/or the presence of a gas in the gas,
the binder is as follows: one or more of polyacrylic acid (PAA), Polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), sodium alginate (Alg), Styrene Butadiene Rubber (SBR), LA132, LA133N, LA134, LA135, LA136D and ME 1209.
7. The preparation method according to claim 6, wherein the conductive paste has a solid content of 5 to 30% by mass based on 100% by mass of the conductive paste; the solid content includes the thickener, a binder, the conductive agent, the antifoaming agent, and the active material; wherein,
the thickening agent is: the adhesive is as follows: the conductive agent: the defoaming agent comprises the following components: the mass ratio of the active substances is 0.1-2.0%: 0.5-15%: 0.5-15%: 0.1-5%: 70 to 97.5 percent
8. The method of claim 7, further comprising, prior to the agitating of the first homogenate, the step of preparing a thickener solution, the step comprising: mixing CMC and deionized water until the whole is clear and transparent, wherein the mass ratio of the CMC to the deionized water is 0.5-2%: 98-99.5%;
60-80% of the total amount of the thickener solution added during the first homogenizing and stirring, and the rest of the thickener solution is added into the conductive paste through the second homogenizing and stirring.
9. The method according to claim 8, wherein the first homogenizing mixer is rotated at a speed of 300 to 600r/min, and the second homogenizing mixer is rotated at a speed of 10 to 120 r/min; and the first homogenate stirring and the second homogenate stirring both adopt the bidirectional stirring mode of alternating forward rotation and reverse rotation.
10. The method of any one of claims 1-9, wherein the ball mill is a planetary ball mill, including a single planetary ball mill, an all-round planetary ball mill, a horizontal planetary ball mill, a variable temperature planetary ball mill, a double planetary ball mill, an ultrasonic planetary ball mill, a liquid nitrogen type planetary ball mill, a novel semicircular planetary ball mill.
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