CN112038570A - Silicon-carbon cathode slurry, slurry mixing method and application - Google Patents
Silicon-carbon cathode slurry, slurry mixing method and application Download PDFInfo
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- CN112038570A CN112038570A CN202011004154.XA CN202011004154A CN112038570A CN 112038570 A CN112038570 A CN 112038570A CN 202011004154 A CN202011004154 A CN 202011004154A CN 112038570 A CN112038570 A CN 112038570A
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- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 238000002156 mixing Methods 0.000 title claims abstract description 52
- 239000002002 slurry Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 21
- 239000006257 cathode slurry Substances 0.000 title description 7
- 239000011267 electrode slurry Substances 0.000 claims abstract description 26
- 239000000654 additive Substances 0.000 claims abstract description 20
- 230000000996 additive effect Effects 0.000 claims abstract description 20
- 238000009736 wetting Methods 0.000 claims abstract description 15
- 230000006872 improvement Effects 0.000 claims abstract description 13
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 7
- 239000004094 surface-active agent Substances 0.000 claims abstract description 7
- 239000003292 glue Substances 0.000 claims description 29
- 239000011230 binding agent Substances 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 21
- 239000006258 conductive agent Substances 0.000 claims description 16
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 11
- 239000007773 negative electrode material Substances 0.000 claims description 10
- 239000010405 anode material Substances 0.000 claims description 6
- 230000008595 infiltration Effects 0.000 claims description 6
- 238000001764 infiltration Methods 0.000 claims description 6
- 239000006256 anode slurry Substances 0.000 claims description 5
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 235000019832 sodium triphosphate Nutrition 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 3
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 claims description 3
- 238000004026 adhesive bonding Methods 0.000 claims description 2
- 238000000576 coating method Methods 0.000 abstract description 18
- 239000003792 electrolyte Substances 0.000 abstract description 17
- 239000011248 coating agent Substances 0.000 abstract description 15
- 230000008569 process Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 31
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 13
- 229910001416 lithium ion Inorganic materials 0.000 description 13
- 239000007787 solid Substances 0.000 description 13
- 238000005096 rolling process Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 238000002791 soaking Methods 0.000 description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 9
- 239000011889 copper foil Substances 0.000 description 9
- 239000013543 active substance Substances 0.000 description 8
- 238000001035 drying Methods 0.000 description 6
- 238000005056 compaction Methods 0.000 description 5
- 239000004570 mortar (masonry) Substances 0.000 description 5
- 239000011149 active material Substances 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 230000007480 spreading Effects 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
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 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
- 239000002245 particle Substances 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
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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
- 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
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- 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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses silicon-carbon negative electrode slurry, a slurry mixing method and application, wherein a wetting improvement additive is added into the silicon-carbon negative electrode slurry in the slurry mixing process, the wetting improvement additive is a hydrophobic surfactant, so that the electrolyte wetting effect of a silicon-carbon negative electrode piece obtained by coating the silicon-carbon negative electrode slurry is improved, and the cycle performance of a button cell prepared by coating the silicon-carbon negative electrode slurry is improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to silicon-carbon negative electrode slurry, a slurry mixing method and application of the silicon-carbon negative electrode slurry.
Background
The lithium ion battery is a new type of high-energy secondary battery which is developed rapidly, mainly has many advantages, and with the rapid development of applications in portable electronic devices, power automobiles and other aspects, the research and development of lithium ion batteries with higher energy density, longer cycle life and lower preparation cost are urgently needed, wherein the energy density is a key factor. The total quality of the battery is closely related to the capacity of the anode material and the cathode material, and the specific capacity of the current anode material does not exceed 374mAh/g, which means that the capacity of the whole battery is improved, and people have to focus eyes into the anode material.
Si has ultrahigh theoretical specific capacity (3579mAh/g Li)15Si4) Low intercalation potential (less than 0.5V Li/Li +), environmental protection, abundant reserves and the like are concerned, and the lithium ion battery cathode material is considered as the next generation of high-performance lithium ion battery cathode material. The silicon-carbon composite material is an important direction for future development of the lithium ion battery cathode, and the prepared silicon-carbon cathode is an important novel cathode material which is beneficial to realizing high energy density and high endurance.
However, continuous pursuit of high energy density of the battery may cause that the capacity of the battery cannot be exerted or the rate performance is reduced, and the wettability of the electrolyte to the pole piece is one of the main factors causing the performance reduction, so that higher requirements are put forward on the manufacturing process of the battery pole piece. The compaction density is an important index in the production process of the lithium ion battery electrode, generally speaking, the higher the compaction density is, more electrodes can be filled in the lithium ion battery per unit volume, and meanwhile, the total proportion of active substances can be increased, so that the volume energy density of the battery can be increased, and the mass energy density of the lithium battery can be increased. However, the higher the pole piece compaction density is, the better the battery performance is, because the compaction density is inversely proportional to the porosity of the electrode, the larger the compaction density is, the larger the extrusion degree between material particles is, the smaller the porosity of the pole piece is, the poorer the electrolyte absorption performance of the pole piece is, and the more difficult the electrolyte is to infiltrate, which directly results in that the specific capacity of the material is exerted lower, the liquid retention capacity of the battery is poorer, the polarization of the battery in the cycle process is large, the attenuation is larger, and the increase of the internal resistance is particularly obvious.
Disclosure of Invention
In view of the above, the present invention needs to provide a silicon-carbon negative electrode slurry, in which a hydrophobic surfactant is added to the slurry as a wetting improvement additive, so as to improve an electrolyte wetting effect of a silicon-carbon negative electrode sheet coated with the silicon-carbon negative electrode slurry, so as to solve the above problems.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides silicon-carbon cathode slurry, wherein a wetting improvement additive is added into the silicon-carbon cathode slurry, and the wetting improvement additive is a hydrophobic surfactant.
Further, the hydrophobic surfactant is selected from one of sodium tripolyphosphate, sodium stearate and glycol.
Further, in the silicon-carbon anode slurry, the infiltration improving additive and the silicon-carbon anode material are mixed in a mass ratio of 1: 20-40, the composition of the silicon carbon anode material is conventional in the art, and in some embodiments of the invention, is SiO/C.
The invention also provides a slurry mixing method of the silicon-carbon negative electrode slurry, which comprises the following steps:
mixing the silicon-carbon negative electrode material with the infiltration improving additive to obtain a uniform mixture;
gluing a first binder to prepare a glue solution, adding a conductive agent into the glue solution, and sequentially carrying out low-speed premixing, high-speed mixing and defoaming to obtain a first slurry;
adding the mixture into the first slurry, and sequentially carrying out low-speed premixing, high-speed mixing and defoaming to obtain a second slurry;
and adding a second binder solution into the second slurry, stirring, and defoaming to obtain the silicon-carbon negative electrode slurry.
The infiltration improving additive is added in the slurry mixing process of the silicon-carbon cathode slurry, so that the slurry mixing method is simple, and the conditions are mild and controllable.
Further, the silicon-carbon negative electrode material: a first binder: a second binder: the mass ratio of the conductive agent is 94-96: 1-2: 1-2: 1-1.5.
Further, the first binder, the second binder and the conductive agent in the present invention may be conventional ones in the art and are not particularly limited, and preferably, in some embodiments of the present invention, the first binder is selected from CMC, the second binder is selected from SBR, and the conductive agent is selected from SP;
the mass fraction of the glue solution is 0.8-1.5%, and the mass fraction of the second binder solution is 45-50%.
Further, the first binder is sized into a glue solution, then the conductive agent is added into the glue solution, and low-speed premixing, high-speed mixing and defoaming are sequentially performed to obtain the first slurry, which comprises the following specific steps: the first adhesive is rubberized to prepare a glue solution, then the conductive agent is added into the glue solution, and the first adhesive is premixed at a low speed of 1000rpm of 800-.
Further, the step of adding the mixture into the first slurry, and sequentially performing low-speed premixing, high-speed mixing and defoaming to obtain a second slurry comprises the following specific steps: the mixture is added into the first slurry, and is premixed at a low speed of 1000rpm for 1-3min at 800-.
Further, adding a second binder solution into the second slurry, stirring and defoaming to obtain the silicon-carbon negative electrode slurry, wherein the specific steps of: adding a second binder solution into the second slurry, stirring at 1000-.
The invention also provides application of the silicon-carbon negative electrode slurry in preparation of a silicon-carbon negative electrode piece. It is understood that the method for preparing the silicon-carbon negative pole piece by coating and rolling the silicon-carbon negative pole slurry is a conventional method in the field, and is not particularly limited, and in some specific embodiments of the invention, the coating process is as follows: taking a copper foil (completely covering the vent holes of the coating machine) with a proper area and 6 microns on the coating machine, opening a vacuum pump and a switch of the coating machine, and wiping the copper foil with alcohol to ensure that the surface of the copper foil is clean; transferring the silicon-carbon negative electrode slurry onto copper foil, and uniformly spreading the slurry to a proper width; selecting a scraper with the specification of 100-; and after coating, transferring the pole piece into a drying oven for drying at 85-120 ℃ for 2-5 h. The rolling process is as follows: cutting off the head and the tail of the dried pole piece, cutting the dried pole piece into small sections with the width of about 2cm, adjusting the scale of a roller press to 5-10 for rolling (properly adjusting according to the thickness of copper foil), cleaning the roller press before rolling, and enabling the pole piece to be in a medium curling state after rolling, wherein the surface of the pole piece is smooth and does not drop materials. It is to be understood that the coating process and the rolling process are only examples, and the coating process and the rolling process are conventional in the art and are not specifically described herein.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the hydrophobic surfactant is added as the wetting improvement additive in the process of mixing the silicon-carbon cathode slurry, so that the wetting performance of the electrolyte is improved, the silicon-carbon cathode pole piece prepared from the silicon-carbon cathode slurry has higher energy density, the lithium ion battery has higher capacity in the charging and discharging processes, and lithium ions can be well diffused in the electrode material, so that the lithium ion battery has lower transmission resistance under higher current density, and the lithium ion battery has good rate capability.
Drawings
FIG. 1 is a graph showing the contact angle of the electrolyte and the electrode sheet tested in comparative example 1;
FIG. 2 is the contact angle of the electrolyte solution tested in example 1 with the pole piece;
fig. 3 is a comparison of the cycle performance of the lithium ion batteries prepared in comparative example 1 and example 1.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Example 1
3g of silicon-carbon negative electrode material and 0.1g of ethylene glycol are put into a mortar to be ground for 5min and uniformly mixed to obtain an active material mixture for later use.
Preparing CMC into glue solution with the mass fraction of 1%, putting 6g of CMC glue solution into a clean and dry pulp mixing tank, adding 0.06g of conductive agent SP into the glue solution, putting the pulp mixing tank into a pulp mixing machine, premixing for 1.5min at a low speed of 800rpm, then mixing for 10min at a high speed of 1900rpm, and finally defoaming for 1min at the speed of 800rpm to obtain first slurry with the solid content of 1.98%;
adding the prepared active substance mixture into the first slurry, premixing at a low speed of 800rpm for 1min, then mixing at a high speed of 1900rpm for 10min, and finally defoaming at 800rpm for 1min to obtain a second slurry with a solid content of 34.06%;
and adding 0.1g of SBR solution with the mass fraction of 48.7% into the second slurry, stirring at the rotating speed of 1000rpm for 3min, and defoaming at the rotating speed of 800rpm for 1min to obtain silicon-carbon negative electrode slurry with the solid content of 34.22%.
Comparative example 1
Compared with the method in example 1, the method for mixing the silicon-carbon negative electrode slurry in the comparative example is the same as that in example 1 except that the infiltration improving additive is not added, namely the active material mixture in example 1 is changed to 3g of silicon-carbon negative electrode material.
Example 2
3g of silicon-carbon negative electrode material and 0.15g of ethylene glycol are put into a mortar to be ground for 10min and uniformly mixed to obtain an active material mixture for later use.
Preparing CMC into glue solution with the mass fraction of 1%, putting 6g of CMC glue solution into a clean and dry pulp mixing tank, adding 0.06g of conductive agent SP into the glue solution, putting the pulp mixing tank into a pulp mixing machine, firstly premixing for 2min at a low speed of 800rpm, then mixing for 10min at a high speed of 2000rpm, and finally defoaming for 3min at a rotating speed of 1000rpm to obtain first slurry with the solid content of 1.98%;
adding the prepared active substance mixture into the first slurry, premixing for 3min at a low speed of 1000rpm, then mixing for 10min at a high speed of 2000rpm, and finally defoaming for 3min at 1000rpm to obtain a second slurry with the solid content of 33.87%;
and adding 0.1g of SBR solution with the mass fraction of 48.7% into the second slurry, stirring at 1000rpm for 3min, and defoaming at 1000rpm for 3min to obtain silicon-carbon negative electrode slurry with the solid content of 34.03%.
Example 3
5g of silicon-carbon negative electrode material and 0.15g of sodium stearate are put into a mortar to be ground for 5min and uniformly mixed to obtain an active material mixture for later use.
Preparing CMC into glue solution with the mass fraction of 1%, putting 6g of CMC glue solution into a clean and dry pulp mixing tank, adding 0.06g of conductive agent SP into the glue solution, putting the pulp mixing tank into a pulp mixing machine, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 2min at a speed of 1000rpm to obtain first slurry with the solid content of 1.98%;
adding the prepared active substance mixture into the first slurry, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 2min at 1000rpm to obtain a second slurry with the solid content of 47.01%;
and adding 0.2g of SBR solution with the mass fraction of 48.7% into the second slurry, stirring at 1200rpm for 3min, and defoaming at 800rpm for 3min to obtain 47.04% of silicon-carbon negative electrode slurry.
Example 4
And (3) putting 5g of silicon-carbon negative electrode material and 0.15g of sodium tripolyphosphate into a mortar, grinding for 5min, and uniformly mixing to obtain an active substance mixture for later use.
Preparing CMC into glue solution with the mass fraction of 1%, putting 6g of CMC glue solution into a clean and dry pulp mixing tank, adding 0.06g of conductive agent SP into the glue solution, putting the pulp mixing tank into a pulp mixing machine, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 3min at a speed of 1000rpm to obtain first slurry with the solid content of 1.98%;
adding the prepared active substance mixture into the first slurry, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 3min at 1000rpm to obtain a second slurry with the solid content of 47.01%;
and adding 0.2g of SBR solution with the mass fraction of 48.7% into the second slurry, stirring at 1200rpm for 5min, and defoaming at 1000rpm for 3min to obtain 47.04% of silicon-carbon negative electrode slurry.
Example 5
And (3) putting 4g of silicon-carbon negative electrode material and 0.15g of sodium tripolyphosphate into a mortar, grinding for 8min, and uniformly mixing to obtain an active substance mixture for later use.
Preparing CMC into glue solution with the mass fraction of 1%, putting 6g of CMC glue solution into a clean and dry pulp mixing tank, adding 0.09g of conductive agent SP into the glue solution, putting the pulp mixing tank into a pulp mixing machine, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 3min at a speed of 1000rpm to obtain first slurry with the solid content of 1.98%;
adding the prepared active substance mixture into the first slurry, premixing for 3min at a low speed of 1000rpm, then mixing for 15min at a high speed of 2000rpm, and finally defoaming for 3min at 1000rpm to obtain a second slurry with a solid content of 41.82%;
and adding 0.2g of SBR solution with the mass fraction of 48.7% into the second slurry, stirring at the rotating speed of 1200rpm for 5min, and defoaming at the rotating speed of 1000rpm for 3min to obtain silicon-carbon negative electrode slurry with the solid content of 41.95%.
Test example
1. The silicon-carbon negative electrode slurry in the examples 1 to 5 and the comparative example 1 is respectively prepared into silicon-carbon negative electrode plates, and the specific coating and rolling procedures are as follows:
coating: taking a copper foil (completely covering the vent holes of the coating machine) with a proper area and 6 microns on the coating machine, opening a vacuum pump and a switch of the coating machine, and wiping the copper foil with alcohol to ensure that the surface of the copper foil is clean;
transferring the silicon-carbon negative electrode slurry onto copper foil, and uniformly spreading the slurry to a proper width;
selecting a scraper with the specification of 100 for coating;
and after coating is finished, transferring the pole piece into a drying oven for drying, wherein the drying temperature is 85 ℃, and the drying time is 2 hours.
Rolling: cutting off the head and the tail of the dried pole piece, cutting the dried pole piece into small sections with the width of about 2cm, adjusting the scale of a roller press to be 5 for rolling, cleaning the roller press before rolling, and ensuring that the pole piece is in a medium curling state after rolling and the surface of the pole piece is smooth and does not drop materials.
The silicon-carbon negative pole pieces obtained in the examples and the comparative examples are respectively subjected to soaking time and contact angle tests, wherein the soaking time in the example 1 and the soaking time in the comparative example 1 are as shown in the following table 1:
table 1 wetting time comparison of example 1 and comparative example 1
Wherein, (1) soaking time test: the rolled pole piece is put into a glove box, 3mL of electrolyte (the electrolyte composition is EC: PC: EMC: 35:5:60, additive VC: 2.5%, lithium salt: 1-1.1M) is absorbed by a liquid-transferring gun and dripped on the pole piece, the time for the electrolyte to be completely immersed into the pole piece is read, 5 groups are measured, and the average value is calculated.
(2) Contact angle test: 3mL of electrolyte is dripped onto the pole piece, and a contact angle tester is used for measuring the contact angle between the electrolyte and the pole piece.
As can be seen from table 1, the average time for soaking the electrode sheet with the electrolyte without the soaking improvement additive in comparative example 1 is about 5min, while the time for soaking the electrode sheet with the electrolyte after the soaking improvement additive is added in example 1 is about 3min, and the soaking condition of the electrolyte on the surface of the electrode is better. Furthermore, as can be seen from the contact angles between the electrolyte and the pole piece in fig. 1 and fig. 2, the contact angle of the pole piece in example 1 is smaller than that in comparative example 1, and the electrolyte on the surface of the pole piece is better soaked after the soaking improvement additive is added.
2. The silicon-carbon negative electrode plates obtained by coating in example 1 and comparative example 1 were assembled into button cells, and the cycling performance was tested under the 0.1C condition, respectively, and the results are shown in fig. 3. It can be seen that the button cell assembled in example 1 with the wetting improvement additive added has better cycle performance, which indicates that the addition of the wetting improvement additive improves the wetting performance of the pole piece, and then improves the cycle performance of the cell.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The silicon-carbon anode slurry is characterized in that a wetting improvement additive is added into the silicon-carbon anode slurry, and the wetting improvement additive is a hydrophobic surfactant.
2. The silicon carbon negative electrode slurry of claim 1, wherein the hydrophobic surfactant is one selected from the group consisting of sodium tripolyphosphate, sodium stearate, and ethylene glycol.
3. The silicon-carbon anode slurry of claim 1, wherein the infiltration improving additive and the silicon-carbon anode material are present in the silicon-carbon anode slurry in a mass ratio of 1: 20-40.
4. The slurry mixing method of the silicon-carbon negative electrode slurry as claimed in any one of claims 1 to 3, characterized by comprising the following steps:
mixing the silicon-carbon negative electrode material with the infiltration improving additive to obtain a uniform mixture;
gluing a first binder to prepare a glue solution, adding a conductive agent into the glue solution, and sequentially carrying out low-speed premixing, high-speed mixing and defoaming to obtain a first slurry;
adding the mixture into the first slurry, and sequentially carrying out low-speed premixing, high-speed mixing and defoaming to obtain a second slurry;
and adding a second binder solution into the second slurry, stirring, and defoaming to obtain the silicon-carbon negative electrode slurry.
5. The slurry mixing method according to claim 4, wherein the silicon-carbon negative electrode material: a first binder: a second binder: the mass ratio of the conductive agent is 94-96: 1-2: 1-2: 1-1.5.
6. The method of claim 4, wherein the first binder is selected from CMC, the second binder is selected from SBR, the conductive agent is selected from SP;
the mass fraction of the glue solution is 0.8-1.5%, and the mass fraction of the second binder solution is 45-50%.
7. The pulp mixing method according to claim 4, wherein the first binder is sized to form a glue solution, then a conductive agent is added into the glue solution, and the steps of low-speed premixing, high-speed mixing and defoaming are sequentially performed to obtain a first pulp are as follows: the first adhesive is rubberized to prepare a glue solution, then the conductive agent is added into the glue solution, and the first adhesive is premixed at a low speed of 1000rpm of 800-.
8. The pulp mixing method according to claim 4, wherein the specific steps of adding the mixture into the first pulp, sequentially carrying out low-speed premixing, high-speed mixing and defoaming to obtain a second pulp are as follows: the mixture is added into the first slurry, and is premixed at a low speed of 1000rpm for 1-3min at 800-.
9. The slurry mixing method according to claim 4, wherein the concrete steps of adding a second binder solution into the second slurry, stirring and defoaming to obtain the silicon-carbon negative electrode slurry are as follows: adding a second binder solution into the second slurry, stirring at 1000-.
10. The use of the silicon-carbon negative electrode slurry according to any one of claims 1 to 3 in the preparation of a silicon-carbon negative electrode sheet.
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