CN117096268A - Negative electrode of sodium ion battery, negative electrode slurry and preparation method of negative electrode slurry - Google Patents
Negative electrode of sodium ion battery, negative electrode slurry and preparation method of negative electrode slurry Download PDFInfo
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- CN117096268A CN117096268A CN202311345455.2A CN202311345455A CN117096268A CN 117096268 A CN117096268 A CN 117096268A CN 202311345455 A CN202311345455 A CN 202311345455A CN 117096268 A CN117096268 A CN 117096268A
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- slurry
- negative electrode
- binder
- hard carbon
- stirring
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- 239000011267 electrode slurry Substances 0.000 title claims abstract description 37
- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 27
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000011230 binding agent Substances 0.000 claims abstract description 121
- 229910021385 hard carbon Inorganic materials 0.000 claims abstract description 74
- 239000006258 conductive agent Substances 0.000 claims abstract description 56
- 239000002270 dispersing agent Substances 0.000 claims abstract description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 38
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000000853 adhesive Substances 0.000 claims abstract description 21
- 230000001070 adhesive effect Effects 0.000 claims abstract description 21
- 239000011149 active material Substances 0.000 claims abstract description 19
- 239000007773 negative electrode material Substances 0.000 claims abstract description 18
- 229920001940 conductive polymer Polymers 0.000 claims abstract description 12
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 10
- 238000004132 cross linking Methods 0.000 claims abstract description 8
- 239000002002 slurry Substances 0.000 claims description 118
- 238000003756 stirring Methods 0.000 claims description 90
- 239000007787 solid Substances 0.000 claims description 54
- 239000003292 glue Substances 0.000 claims description 37
- 239000000843 powder Substances 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 33
- 150000001875 compounds Chemical class 0.000 claims description 28
- KAESVJOAVNADME-UHFFFAOYSA-N Pyrrole Chemical compound C=1C=CNC=1 KAESVJOAVNADME-UHFFFAOYSA-N 0.000 claims description 26
- 238000002156 mixing Methods 0.000 claims description 26
- 239000002904 solvent Substances 0.000 claims description 24
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 23
- 229920002125 Sokalan® Polymers 0.000 claims description 18
- 239000004584 polyacrylic acid Substances 0.000 claims description 18
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 17
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 17
- 239000003795 chemical substances by application Substances 0.000 claims description 17
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 17
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 16
- 239000003999 initiator Substances 0.000 claims description 9
- 239000000178 monomer Substances 0.000 claims description 9
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 8
- 239000006229 carbon black Substances 0.000 claims description 8
- 238000004898 kneading Methods 0.000 claims description 8
- 239000002028 Biomass Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 claims description 4
- NIHNNTQXNPWCJQ-UHFFFAOYSA-N fluorene Chemical compound C1=CC=C2CC3=CC=CC=C3C2=C1 NIHNNTQXNPWCJQ-UHFFFAOYSA-N 0.000 claims description 4
- BBEAQIROQSPTKN-UHFFFAOYSA-N pyrene Chemical compound C1=CC=C2C=CC3=CC=CC4=CC=C1C2=C43 BBEAQIROQSPTKN-UHFFFAOYSA-N 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- FHVDTGUDJYJELY-UHFFFAOYSA-N 6-{[2-carboxy-4,5-dihydroxy-6-(phosphanyloxy)oxan-3-yl]oxy}-4,5-dihydroxy-3-phosphanyloxane-2-carboxylic acid Chemical compound O1C(C(O)=O)C(P)C(O)C(O)C1OC1C(C(O)=O)OC(OP)C(O)C1O FHVDTGUDJYJELY-UHFFFAOYSA-N 0.000 claims description 2
- 229920001661 Chitosan Polymers 0.000 claims description 2
- 229920002907 Guar gum Polymers 0.000 claims description 2
- 240000007472 Leucaena leucocephala Species 0.000 claims description 2
- 235000010643 Leucaena leucocephala Nutrition 0.000 claims description 2
- 230000009471 action Effects 0.000 claims description 2
- 229940072056 alginate Drugs 0.000 claims description 2
- 235000010443 alginic acid Nutrition 0.000 claims description 2
- 229920000615 alginic acid Polymers 0.000 claims description 2
- 239000002134 carbon nanofiber Substances 0.000 claims description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 2
- 239000002041 carbon nanotube Substances 0.000 claims description 2
- 229940045110 chitosan Drugs 0.000 claims description 2
- 229960003638 dopamine Drugs 0.000 claims description 2
- GVEPBJHOBDJJJI-UHFFFAOYSA-N fluoranthrene Natural products C1=CC(C2=CC=CC=C22)=C3C2=CC=CC3=C1 GVEPBJHOBDJJJI-UHFFFAOYSA-N 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- 239000000665 guar gum Substances 0.000 claims description 2
- 235000010417 guar gum Nutrition 0.000 claims description 2
- 229960002154 guar gum Drugs 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 238000006116 polymerization reaction Methods 0.000 claims description 2
- 239000000230 xanthan gum Substances 0.000 claims description 2
- 235000010493 xanthan gum Nutrition 0.000 claims description 2
- 229920001285 xanthan gum Polymers 0.000 claims description 2
- 229940082509 xanthan gum Drugs 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 17
- 125000000524 functional group Chemical group 0.000 abstract description 8
- 239000002245 particle Substances 0.000 abstract description 8
- 238000005054 agglomeration Methods 0.000 abstract description 3
- 230000002776 aggregation Effects 0.000 abstract description 3
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 3
- 239000001257 hydrogen Substances 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 238000005886 esterification reaction Methods 0.000 abstract description 2
- 238000002161 passivation Methods 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 38
- 238000011068 loading method Methods 0.000 description 24
- 239000011248 coating agent Substances 0.000 description 18
- 238000000576 coating method Methods 0.000 description 18
- 238000004513 sizing Methods 0.000 description 16
- 239000010410 layer Substances 0.000 description 13
- 239000011888 foil Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 239000002174 Styrene-butadiene Substances 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 8
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000007873 sieving Methods 0.000 description 7
- 239000006185 dispersion Substances 0.000 description 6
- 230000001105 regulatory effect Effects 0.000 description 6
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 5
- 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 5
- 239000008367 deionised water Substances 0.000 description 5
- 229910021641 deionized water Inorganic materials 0.000 description 5
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 3
- 238000004537 pulping Methods 0.000 description 3
- 238000009736 wetting Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 239000006256 anode slurry Substances 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000009775 high-speed stirring Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- 238000012695 Interfacial polymerization Methods 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 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 description 1
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 1
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 239000006257 cathode slurry Substances 0.000 description 1
- 230000009194 climbing Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007580 dry-mixing Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920000767 polyaniline Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920000128 polypyrrole Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 239000012966 redox initiator Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000003232 water-soluble binding agent Substances 0.000 description 1
Classifications
-
- 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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- 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
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
-
- 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
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to a sodium ion battery negative electrode, negative electrode slurry and a preparation method of the negative electrode slurry. The negative electrode prepared by the invention comprises a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, wherein the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a modified binder and a binder; or; the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer. The modified binder and the hard carbon surface of the invention are provided with a large number of reactive functional groups, and a uniform passivation film can be formed through hydrogen bond or esterification reaction between the functional groups, so that the agglomeration effect between molecules is reduced, and the binder is easy to wet, thereby uniformly covering the surfaces of carbon particles.
Description
Technical Field
The invention belongs to the field of battery negative electrode materials, and particularly relates to a sodium ion battery negative electrode, negative electrode slurry and a preparation method of the negative electrode slurry.
Background
Sodium ions are 34.2% larger than lithium ions in radius, which results in the inability of sodium ions to intercalate into graphite anodes with smaller interlayer spacing. Hard carbon materials are considered to be ideal negative electrode materials for sodium ion batteries in the future because of their larger interlayer spacing than graphite.
The hard carbon material is usually obtained by taking biomass or resin as a precursor, carbonizing at about 1000-1500 ℃ for a certain time, crushing, mixing and sieving. However, the powder particles have sharp edges, smaller particle size and larger surface area, are difficult to wet and uniformly disperse in water-based slurry, and are easy to agglomerate and settle. When in coating, the surface of the film surface has obvious scratches, particles and bubbles, the adhesion of the pole piece is poor, and the powder is easy to fall off.
The uniform wetting of the hard carbon powder is the core step of slurry preparation, the solvent is added in the initial stage to be too little to wet all the powder, the hard carbon powder is bound to be agglomerated, and the hard carbon powder is difficult to open later; moreover, in the case of overdry, the slurry is easy to "climb a rod" and cannot play a stirring effect; if the solvent is too much, the slurry easily flows, the effect of the shearing force of the stirring paddle is reduced, and the kneading and stirring do not play a role in crushing and agglomerating by the kneading force.
The main influencing factors that lead to the above series of problems are the contact situation and the dispersion effect between the components in the slurry. The kind and the adding proportion of the binder have obvious influence on the contact wetting condition and the adhesiveness of each component in the slurry, and the adding sequence of materials, the stirring speed and the like in the slurry preparation process can influence the dispersing effect among the components.
Because PVDF has good chemical and electrochemical stability, most electrodes use commercial PVDF as a binder. But the PVDF binder has lower cohesiveness, weaker mechanical strength, and the used N-methyl pyrrolidone solvent has high production cost, is easy to volatilize and toxic, has higher industrialized use cost and serious environmental pollution. The water-soluble binder contains a large number of-OH and-COOH functional groups, and can generate strong hydrogen bonds, ion-dipole interactions or chemical bonds with the active material. Meanwhile, the water-based binder solvent is water, is environment-friendly and low in cost, and is a common binder for the current negative electrode system.
In the existing negative electrode active material, carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) are commonly used in combination, wherein CMC mainly plays a role in dispersion and SBR plays a role in adhesion. Because the hard carbon is extremely easy to settle in the pulping process and the particle-particle adhesion is poor, the conventional method at present is to enhance the dispersion effect by improving the CMC load in the slurry, and the SBR load is improved to increase the particle adhesion. However, the viscosity of the slurry finally obtained is high due to too much CMC addition. In order to achieve better coating effect, the solid content of the discharged slurry is mostly lower than 50%, and the contact angle of the slurry and the photo-aluminum foil is close to 90 degrees. At the moment, the wetting effect between the slurry and the foil is poor, the problems of obvious shrinkage, tailing and thick edges are extremely easy to occur at the edge of the coating during coating, the adhesiveness between the coating and the foil can be obviously affected, and the problem of edge overvoltage and black edges of the pole piece are extremely easy to occur in the subsequent rolling process.
Disclosure of Invention
The invention aims at solving the problems in the prior art and provides a sodium ion battery anode, anode slurry and an anode slurry preparation method.
The aim of the invention can be achieved by the following scheme:
a negative electrode of a sodium ion battery, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, and the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a modified binder and a binder; or; the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer.
As an embodiment of the present invention, the active material comprises the following components in parts by mass: 93-97 parts of hard carbon, 0.5-3 parts of conductive agent, 0-0.5 part of dispersing agent, 1.5-3.5 parts of modified binder and 0.1-2.5 parts of binder.
As an embodiment of the present invention, the hard carbon includes one or both of biomass-based hard carbon and resin-based hard carbon.
As an embodiment of the present invention, the conductive agent includes one or more of carbon black, carbon nanotubes, carbon nanofibers, and graphene.
As one embodiment of the present invention, the dispersant comprises carboxymethyl cellulose CMC.
As one embodiment of the invention, the modified binder is obtained by crosslinking polymerization of an aqueous binder and a conductive polymer monomer under the action of an initiator; the mass ratio of the aqueous binder to the electropolymerized monomer is (1-10): (1-10).
The water-based binder comprises carboxymethyl cellulose, polyacrylic acid, alginate, chitosan, guar gum, xanthan gum, acacia, and one or more of derivatives thereof; the conductive polymer monomer comprises dopamine, aniline, pyrrole, fluorene, pyrene and one of derivatives of the above materials; the initiator is one of a peroxide initiator, an azo initiator and a redox initiator. The modified binder not only has a large amount of reactive functional groups (such as-OH, -COOH and the like), but also has polar functional groups and conjugated structures (such as C-O, C-N and the like). If the aqueous binder and the conductive polymer are directly mixed, the dispersion uniformity of the conductive polymer in the aqueous binder is difficult to ensure, and the polymer is easy to agglomerate and settle to influence the contact condition among the components in the slurry.
As one embodiment of the present invention, the binder includes styrene-butadiene rubber.
As an embodiment of the present invention, the modified binder loading is 1 to 4 times that of the binder.
The invention also provides a negative electrode slurry for preparing the negative electrode of the sodium ion battery, which comprises, by mass, 50-60% of active materials, 1.5-11.5% of impregnating compounds and 38.5-48.5% of solvents.
As one embodiment of the present invention, the sizing agent includes one or more of N-methylpyrrolidone, ethanol, propanol, and butanediol.
As an embodiment of the present invention, the solvent includes water.
The invention also provides a preparation method of the sodium ion battery cathode, which comprises a first method or a second method;
the active material of the first method comprises a dispersing agent, and the steps are as follows:
s1, dissolving a dispersing agent in a solvent to obtain a glue solution I, wherein the solid content of the glue solution I is 1-2%;
s2, respectively baking the conductive agent and the hard carbon powder, adding the conductive agent into the hard carbon powder, and stirring to obtain dry powder I;
s3, adding glue once and kneading: adding part of the glue solution I and at least part of the modified binder into the dry powder I, and stirring to obtain slurry II, wherein the solid content of the slurry is 60-70%; the partial glue solution I is 0.1-70% of the total volume of the glue solution I, and the at least partial modified binder is 30-100% of the total mass of the modified binder;
according to the invention, the kneading solid content is regulated to a proper value by regulating the one-time glue adding proportion, so that the hard carbon slurry is kneaded, so that all components in the slurry can be better wetted and dispersed in the initial stage, and the slurry is prevented from agglomerating and climbing at the bottom of the stirring tank, so that equipment clamping and stopping pulping cannot be continued;
s4, secondary glue adding: adding the residual glue solution I and the residual modified binder into the slurry II, stirring, and adding a solvent to adjust the solid content to obtain a slurry III, wherein the solid content of the slurry is 50-60%;
s5, mixing the binder with the slurry III to obtain slurry IV;
s6, adding the impregnating compound into the slurry IV and stirring to obtain negative electrode slurry;
the active material of the second method does not comprise dispersing agent, and the steps are as follows:
a1, respectively baking the conductive agent and the hard carbon powder, adding the conductive agent into the hard carbon powder, and stirring to obtain dry powder I;
a2, adding at least part of modified binder into the dry powder I, adding solvent, and stirring to obtain slurry II, wherein the solid content of the slurry is 60-70%; at least part of the modified binder means 30-100% of the total mass of the modified binder;
a3, adding the residual modified binder into the slurry II, stirring, and adding a solvent to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 50-60%;
a4, mixing the binder with the slurry III to obtain slurry IV;
and A5, adding the impregnating compound into the slurry IV, and stirring to obtain the negative electrode slurry.
The negative electrode slurry disclosed by the invention is used for baking the conductive agent and the hard carbon in vacuum before pulping, so that the moisture on the surface of the dry powder can be removed, and the problem of local agglomeration of the powder due to exceeding moisture in the dry mixing process is prevented. Meanwhile, the method can remove carbon dioxide, nitrogen and other gases adsorbed on the surface of the hard carbon, and improve the obvious gas production phenomenon of the subsequent slurry.
In step S1 of the first method, the method further includes a step of mixing after the dispersant is dissolved in the solvent, wherein the mixing parameters are as follows: stirring at a low speed for 20-40 min, wherein the revolution speed of the low-speed stirring is 10-30r/min, and the rotation speed of the low-speed stirring is 1-10m/s; then stirring at high speed for 150-300 min, revolution speed of high-speed stirring is 30-60r/min, and rotation speed of high-speed stirring is 10-20m/s.
In step S2 of the first method, the baking is performed under vacuum at 80-160 ℃ for 3-12 hours to ensure the moisture content of <500ppm.
In step S2 of the first method, the mixture is stirred at a low speed for 20 to 40 minutes, the revolution speed of the low speed stirring is 10 to 30r/min, and the rotation speed of the low speed stirring is 1 to 8m/S. The addition of the hard carbon powder is carried out in divided portions, preferably in 3 portions.
In step S3 of the first method, as an embodiment of the present invention, stirring is specifically: without dispersion, firstly reversing for 5-10min, wherein the reversed revolution speed is 10-30r/min, and primarily and uniformly mixing the glue solution; and then forward rotating, kneading the mixture for 60-120 min, and the revolution speed of the forward rotating is 10-30r/min.
In step S4 of the first method, as an embodiment of the present invention, stirring is specifically: dispersing the mixture for 60-200 min, wherein the revolution speed is 30-60r/min, and the rotation speed is 10-20m/s, and the vacuum degree in the stirring tank is required to be kept at < -90kPa in the process.
In step S5 of the first method, as an embodiment of the present invention, the mixing is specifically: stirring the mixture at a low speed for 20-40 min, wherein the revolution speed is 10-30r/min and the rotation speed is 1-10m/s.
In step A1 of the second method, the baking is performed under vacuum at 80-160 ℃ for 3-12 hours to ensure the moisture content of <500ppm.
In step A1 of the second method, the mixture is stirred at a low speed for 20 to 40 minutes, the revolution speed of the low speed stirring is 10 to 30r/min, and the rotation speed of the low speed stirring is 1 to 8m/s. The addition of the hard carbon powder is carried out in divided portions, preferably in 3 portions.
In step A2 of the second method, as an embodiment of the present invention, the stirring is specifically: without dispersion, firstly reversing for 5-10min, wherein the reversed revolution speed is 10-30r/min, and primarily and uniformly mixing the glue solution; and then forward rotating, kneading the mixture for 60-120 min, and the revolution speed of the forward rotating is 10-30r/min.
In step A3 of the second method, as an embodiment of the present invention, the stirring is specifically: dispersing the mixture for 60-200 min, wherein the revolution speed is 30-60r/min, and the rotation speed is 10-20m/s, and the vacuum degree in the stirring tank is required to be kept at < -90kPa in the process.
In step A4 of the second method, as an embodiment of the present invention, the mixing is specifically: stirring the mixture at a low speed for 20-40 min, wherein the revolution speed is 10-30r/min and the rotation speed is 1-10m/s.
Compared with the prior art, the invention has the following beneficial effects:
(1) The modified binder has dispersing effect and binding effect, can replace part or all of CMC and part of binder (SBR), and greatly reduces the load of CMC and binder. This is because the modified binder and the hard carbon surface each have a large number of reactive functional groups, and a uniform passivation film can be formed by hydrogen bonding or esterification reaction between the functional groups, so that the agglomeration effect between molecules is reduced, and the binder is easily wetted, thereby uniformly covering the carbon particle surfaces. Meanwhile, the polar functional groups and the conjugated structure in the modified binder ensure that electrons/ions are conductive in the main chain branched chains, so that the resistivity of the pole piece is reduced, and the subsequent improvement of the dynamic performance of the battery cell is facilitated.
(2) According to the invention, through the use of the modified binder, the dispersing agent and the binder load are reduced, and meanwhile, each component in the slurry is uniformly dispersed, so that the high-solid-content low-viscosity negative electrode slurry and the negative electrode plate with good appearance are prepared. The slurry has higher solid content, lower viscosity, excellent sieving performance, good stability and small contact angle. The negative pole piece has no scratch, particle and bubble, the membrane surface has no obvious shrinkage, tailing and thick edge problems, and the pole piece resistivity is low.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples, which are presented to provide those of ordinary skill in the art with a detailed description of the invention and to provide a further understanding of the invention, are presented in terms of implementation and operation. It should be noted that the protection scope of the present invention is not limited to the following embodiments, and several adjustments and improvements made on the premise of the inventive concept are all within the protection scope of the present invention.
Example 1
The embodiment prepares a negative electrode of a sodium ion battery, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, and the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer. The negative electrode of this example was formed by coating aluminum foil with the following negative electrode slurry.
The negative electrode slurry used for preparing the negative electrode of the sodium ion battery consists of active materials (hard carbon, conductive agent, dispersing agent, modified binder and binder), impregnating compound and solvent, wherein the solvent is water.
The total loading amount of the solid powder in the hard carbon, the conductive agent, the dispersing agent, the modified binder and the binder is calculated by 100% by mass, wherein the loading amount of the hard carbon is as follows: 95.5 percent of conductive agent load is 1.0 percent, dispersant load is 0.5 percent, modified binder load is 2.0 percent and binder load is 1.0 percent. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The hard carbon is biomass-based hard carbon, the conductive agent is carbon black, the dispersing agent is carboxymethyl cellulose (CMC), the modified binder is polyacrylic acid obtained by modifying and polymerizing pyrrole monomers in sodium persulfate initiator solution, and the modified binder is specifically: placing polyacrylic acid into a sodium persulfate solution with the concentration of 50mg/L for soaking for 10 hours, wherein sodium sulfate enters the pores of the polyacrylic acid; placing the soaked polyacrylic acid in an pyrrole organic solution for 12 hours, and performing interfacial polymerization on pyrrole in the organic solution under the initiation of sodium sulfate in polyacrylic acid pores to obtain the modified binder. The mass ratio of the polyacrylic acid to the pyrrole is 5:1, a step of;
the adhesive is Styrene Butadiene Rubber (SBR), and the impregnating compound is N-methylpyrrolidone.
The preparation method of the negative electrode slurry comprises the following steps:
s1, uniformly mixing a dispersing agent CMC and water to obtain a glue solution I, wherein the solid content of the glue solution I is 1.2%;
s2, respectively carrying out vacuum baking on the conductive agent dry powder and the hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s3, adding 65% of the glue solution I obtained in the step S1 (namely, only adding 65% of the total volume of the glue solution prepared in the step S1) into the dry powder I, uniformly stirring all modified binders, and regulating the solid content of a proper amount of water to obtain slurry II, wherein the solid content of the slurry is 67%;
s4, adding the rest 35% of glue solution I (volume) into the slurry II, uniformly stirring, and then adding water to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 54.5%;
s5, uniformly mixing SBR and the slurry III to obtain slurry IV;
and S6, adding the impregnating compound into the slurry IV, uniformly stirring the impregnating compound, sieving the impregnating compound with a 200-mesh sieve to obtain final negative electrode slurry, and coating the slurry on the two sides of the aluminum foil to observe the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, CMC powder and deionized water are added into a stirrer and stirred for 30min at a low speed, wherein the revolution speed is 15r/min and the rotation speed is 5m/S; then stirring at high speed for 200min, wherein the revolution speed is 40r/min and the rotation speed is 15m/s.
In the step S2, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S3, stirring is specifically carried out without dispersing, and the stirring is firstly carried out for 8 minutes in a reverse rotation way, wherein the revolution speed is 20r/min; the mixture was kneaded for 80 minutes again in normal rotation, and its revolution speed was 28r/min.
In the step S4, the mixture is stirred for 60min at a high speed, the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept in the stirring tank in the process.
In step S5, the mixing specifically includes: the mixture was stirred at a low speed for 30min at a revolution speed of 20r/min and a rotation speed of 3m/s.
Example 2
The embodiment prepares a negative electrode of a sodium ion battery, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, and the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer.
The negative electrode slurry used for preparing the negative electrode of the sodium ion battery consists of hard carbon, a conductive agent, a dispersing agent, a modified binder, a sizing agent and a solvent, wherein the solvent is water.
The sum of the loading amounts of the solid powder in the hard carbon, the conductive agent, the dispersing agent, the modified binder and the binder is calculated as 100%, wherein the loading amount of the hard carbon is as follows: 95.5 percent of conductive agent load is 1.0 percent, dispersant load is 0.3 percent, modified binder load is 2.4 percent, and binder load is 0.8 percent. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The hard carbon is biomass-based hard carbon, the conductive agent is carbon black, the dispersing agent is carboxymethyl cellulose (CMC), the modified binder is polyacrylic acid obtained by modifying and polymerizing aniline monomers in sodium persulfate initiator solution, and the modified binder is specifically: firstly, uniformly mixing 400g of polyacrylic acid and 100mL of 1mol L HCI solution, then dropwise adding 1mL of aniline into the solution, stirring for 20min to uniformly mix, then dropwise adding 3.14g of ammonium persulfate into the solution, and stirring for 8h under the condition of ice-water bath to obtain the polyaniline conductive adhesive.
The adhesive is Styrene Butadiene Rubber (SBR), and the impregnating compound is N-methylpyrrolidone.
The preparation method of the negative electrode slurry comprises the following steps:
s1, uniformly mixing a dispersing agent CMC and water to obtain a glue solution I, wherein the solid content of the glue solution I is 1.2%;
s2, respectively carrying out vacuum baking on the conductive agent dry powder and the hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s3, adding 65% of the glue solution I obtained in the step S1 (namely, only adding 65% of the total volume of the glue solution prepared in the step S1) and 80% of modified binder into the dry powder I, uniformly stirring, and adding a proper amount of water to ensure that the solid content of the slurry is 66.5%, thus obtaining slurry II;
s4, adding the residual modified binder into the slurry II, uniformly stirring, and then adding water to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 53%;
s5, uniformly mixing SBR and the slurry III to obtain slurry IV;
and S6, adding the impregnating compound into the slurry IV, uniformly stirring the impregnating compound, sieving the impregnating compound with a 200-mesh sieve to obtain final negative electrode slurry, and coating the slurry on the two sides of the aluminum foil to observe the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, CMC powder and deionized water are added into a stirrer and stirred for 30min at a low speed, wherein the revolution speed is 15r/min and the rotation speed is 5m/S; then stirring at high speed for 200min, wherein the revolution speed is 40r/min and the rotation speed is 15m/s.
In the step S2, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S3, stirring is specifically carried out without dispersing, and the stirring is firstly carried out for 8 minutes in a reverse rotation way, wherein the revolution speed is 20r/min; the mixture was kneaded for 80 minutes again in normal rotation, and its revolution speed was 28r/min.
In the step S4, the mixture is stirred for 60min at a high speed, the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept in the stirring tank in the process.
In step S5, the mixing specifically includes: the mixture was stirred at a low speed for 30min at a revolution speed of 20r/min and a rotation speed of 3m/s.
Example 3
The embodiment prepares a negative electrode of a sodium ion battery, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, and the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer.
The negative electrode slurry used for preparing the negative electrode of the sodium ion battery consists of hard carbon, a conductive agent, a dispersing agent, a modified binder, a sizing agent and a solvent, wherein the solvent is water.
The sum of the loading amounts of the solid powder in the hard carbon, the conductive agent, the dispersing agent, the modified binder and the binder is calculated as 100%, wherein the loading amount of the hard carbon is as follows: 95.0 percent of conductive agent load is 1.0 percent, dispersant load is 0 percent, modified binder load is 3.0 percent, and binder load is 1.0 percent. The modified binder loading was 3 times that of the binder. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The preparation method of the hard carbon is the same as that of the embodiment 1, the conductive agent is carbon black, the dispersing agent is carboxymethyl cellulose (CMC), the modified binder is polyacrylic acid obtained by modifying and polymerizing pyrrole monomers in a sodium persulfate initiator solution, the binder is Styrene Butadiene Rubber (SBR), and the impregnating compound is ethanol.
The preparation method of the negative electrode slurry comprises the following steps:
s1, respectively carrying out vacuum baking on conductive agent dry powder and hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s2, adding 80 mass percent of modified binder into the dry powder I, uniformly stirring, and regulating the solid content by proper amount of water to obtain slurry II, wherein the solid content of the slurry is 67.2%;
s3, uniformly stirring the residual modified binder, adding the residual modified binder into the slurry II, uniformly stirring, and then adding water to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 53.2%;
s4, uniformly mixing SBR and the slurry III to obtain slurry IV;
and S5, adding the impregnating compound into the slurry IV, uniformly stirring the impregnating compound, sieving the impregnating compound with a 200-mesh sieve to obtain final negative electrode slurry, and coating the slurry on the two sides of the aluminum foil to observe the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S2, stirring is specifically that the stirring is not started and dispersed, the stirring is firstly carried out for 8 minutes, the revolution speed is 20r/min, and the mixture is uniformly stirred to prevent equipment from being blocked; the mixture was kneaded for 80 minutes again in normal rotation, and its revolution speed was 28r/min.
In the step S3, the mixture is stirred for 60min at a high speed, the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept at-90 kPa in the stirring tank in the process.
In step S4, the mixing specifically includes: the mixture was stirred at a low speed for 30min at a revolution speed of 20r/min and a rotation speed of 3m/s.
Comparative example 1
This comparative example produced a negative electrode for a sodium ion battery having substantially the same composition and production method as in example 1, except that: in the preparation of the negative electrode slurry, the dispersant and the modified binder were added at once, and the solid content was adjusted without kneading.
The sum of the loading amounts of the solid powder in the hard carbon, the conductive agent, the dispersing agent, the modified binder and the binder is calculated as 100%, wherein the loading amount of the hard carbon is as follows: 95.5 percent of conductive agent load is 1.0 percent, dispersant load is 0.5 percent, modified binder load is 2.0 percent and binder load is 1.0 percent. The modified binder loading was 2 times that of the binder. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The preparation method of the hard carbon is the same as that of the embodiment 1, the conductive agent is carbon black, the dispersing agent is carboxymethyl cellulose (CMC), the modified binder is polyacrylic acid obtained by modifying and polymerizing pyrrole monomers in a sodium persulfate initiator solution, the binder is Styrene Butadiene Rubber (SBR), and the impregnating compound is N-methylpyrrolidone.
The preparation method of the negative electrode slurry comprises the following steps:
s1, uniformly mixing a dispersing agent CMC and water to obtain a glue solution I, wherein the solid content of the glue solution I is 1.2%;
s2, respectively carrying out vacuum baking on the conductive agent dry powder and the hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s3, adding all the glue solution I and all the modified binders into the dry powder I, uniformly stirring, and regulating the solid content by a proper amount of water to obtain slurry II, wherein the solid content of the slurry is 48%;
s4, uniformly mixing SBR and the slurry III to obtain slurry IV;
and S5, adding the impregnating compound into the slurry IV, uniformly stirring the impregnating compound, sieving the impregnating compound with a 200-mesh sieve to obtain final negative electrode slurry, and coating the slurry on the two sides of the aluminum foil to observe the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, CMC powder and deionized water are added into a stirrer and stirred for 30min at a low speed, wherein the revolution speed is 15r/min and the rotation speed is 5m/S; then stirring at high speed for 200min, wherein the revolution speed is 40r/min and the rotation speed is 15m/s.
In the step S2, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S3, the concrete step of stirring is to disperse the mixture at high speed for 140min, wherein the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept at < -90kPa in the stirring tank in the process.
In the step S4, the mixture was stirred at a low speed for 30min, and the revolution speed was 20r/min and the rotation speed was 3m/S.
Comparative example 2
This comparative example produced a negative electrode for a sodium ion battery having substantially the same composition and production method as in example 1, except that: when the negative electrode slurry is prepared, a modified binder is not used, and only a dispersing agent and a binder are used.
The negative electrode slurry consists of hard carbon, a conductive agent, a dispersing agent, a binder impregnating compound and a solvent, wherein the solvent is water.
The sum of the loading amounts of the solid powder in the hard carbon, the conductive agent, the dispersing agent and the binder is 100%, wherein the loading amount of the hard carbon is 95.5%, the loading amount of the conductive agent is 1.0%, the loading amount of the dispersing agent is 0.5%, and the loading amount of the binder is 3%. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The conductive agent is carbon black, the dispersing agent is sodium carboxymethylcellulose (CMC), the binder is Styrene Butadiene Rubber (SBR), and the sizing agent is N-methylpyrrolidone.
The preparation method of the negative electrode slurry comprises the following steps:
s1, uniformly mixing a dispersing agent CMC and water to obtain a glue solution I, wherein the solid content of the glue solution I is 1.2%;
s2, respectively carrying out vacuum baking on the conductive agent dry powder and the hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s3, adding 65% of glue solution I and a proper amount of water into the dry powder I, and uniformly stirring to obtain slurry II, wherein the solid content of the slurry is 67.5%;
s4, adding the residual glue solution I into the slurry II, uniformly stirring, and then adding water to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 54.5%;
s5, uniformly mixing the binder and the slurry III to obtain slurry IV;
and S6, adding the impregnating compound into the slurry IV, uniformly stirring to obtain final negative electrode slurry, uniformly coating the slurry on the two sides of the aluminum foil, and observing the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, CMC powder and deionized water are added into a stirrer and stirred for 30min at a low speed, wherein the revolution speed is 15r/min and the rotation speed is 5m/S; then stirring at high speed for 200min, wherein the revolution speed is 40r/min and the rotation speed is 15m/s.
In the step S2, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S3, the specific step of stirring is that the stirring is carried out without dispersing, the stirring is firstly carried out for 8min, the revolution speed is 20r/min, and the mixture is uniformly stirred to prevent equipment from being blocked; the mixture was kneaded for 80 minutes again in normal rotation, and its revolution speed was 28r/min.
In the step S4, the concrete step of stirring is to disperse the mixture at high speed for 60min, wherein the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept at < -90kPa in the stirring tank in the process.
In step S5, the mixture was stirred at a low speed for 30min, with a revolution speed of 20r/min and a rotation speed of 3m/S.
Comparative example 3
This comparative example produced a negative electrode for a sodium ion battery having substantially the same composition and production method as in example 1, except that: when the cathode slurry is prepared, the modified binder (polypyrrole modified polyacrylic acid) is replaced by pyrrole and polyacrylic acid (two components are not polymerized) with equal amounts.
The sum of the loading amounts of the solid powder in the hard carbon, the conductive agent, the dispersing agent, the modified binder and the binder is calculated as 100%, wherein the loading amount of the hard carbon is as follows: 95.5%, the loading of the conductive agent is 1.0%, the loading of the dispersing agent is 0.5%, the total loading of pyrrole and polyacrylic acid is 2.0% (wherein the mass ratio of the pyrrole to the polyacrylic acid is 1:5), and the loading of the binder is 1.0%. The modified binder loading was 2 times that of the binder. The addition amount of the sizing agent is 1.5% of the final mass of the sizing agent.
The hard carbon is biomass-based hard carbon, the conductive agent is carbon black, the dispersing agent is carboxymethyl cellulose (CMC), the pyrrole loading amount is 0.2 times of polyacrylic acid, the binder is Styrene Butadiene Rubber (SBR), and the impregnating compound is N-methylpyrrolidone.
The preparation method of the negative electrode slurry comprises the following steps:
s1, uniformly mixing a dispersing agent CMC and water to obtain a glue solution I, wherein the solid content of the glue solution I is 1.2%;
s2, respectively carrying out vacuum baking on the conductive agent dry powder and the hard carbon powder at 100 ℃ for 6 hours to ensure that the moisture content is less than 500ppm, adding the conductive agent, and then adding the hard carbon powder for three times and uniformly stirring to obtain dry powder I;
s3, adding 65% of glue solution I, pyrrole and polyacrylic acid into the dry powder I, uniformly stirring, and regulating the solid content with a proper amount of water to obtain slurry II, wherein the solid content of the slurry is 67%;
s4, adding the residual glue solution I into the slurry II, uniformly stirring, and then adding water to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 54.5%;
s5, uniformly mixing SBR and the slurry III to obtain slurry IV;
and S6, adding the impregnating compound into the slurry IV, uniformly stirring the impregnating compound, sieving the impregnating compound with a 200-mesh sieve to obtain final negative electrode slurry, and coating the slurry on the two sides of the aluminum foil to observe the coating effect. The slurry and pole piece related parameters are shown in table 1.
In the step S1, CMC powder and deionized water are added into a stirrer and stirred for 30min at a low speed, wherein the revolution speed is 15r/min and the rotation speed is 5m/S; then stirring at high speed for 200min, wherein the revolution speed is 40r/min and the rotation speed is 15m/s.
In the step S2, the mixture is stirred at a low speed for 35min, wherein the revolution speed is 25r/min and the rotation speed is 5m/S.
In the step S3, the specific step of stirring is that the stirring is carried out without dispersing, the stirring is firstly carried out for 8min, the revolution speed is 20r/min, and the mixture is uniformly stirred to prevent equipment from being blocked; the mixture was kneaded for 80 minutes again in normal rotation, and its revolution speed was 28r/min.
In the step S4, the concrete step of stirring is to disperse the mixture at high speed for 60min, wherein the revolution speed is 45r/min, the rotation speed is 12m/S, and the vacuum degree is required to be kept at < -90kPa in the stirring tank in the process.
In step S5, the mixture was stirred at a low speed for 30min, with a revolution speed of 20r/min and a rotation speed of 3m/S.
The properties of each example related to the slurry and negative electrode sheet prepared in the comparative example are as follows:
and (3) testing the solid content of the slurry bottom layer: filling the prepared slurry into a 250mL beaker, taking the bottom slurry by using a rubber head dropper, and drying. Solid content = mass after slurry drying/wet weight of slurry;
bottom layer solid content 24h increase rate = slurry bottom layer solid content-slurry initial bottom layer solid content after standing for 24 h;
slurry viscosity test: the slurry viscosity tester adopts a Bohler femtoviscometer model LVDV-2T, and uses a No. 3 rotor at a rotating speed of 60r/min for testing.
Contact angle test: the test was performed using a contact angle tester of model OCA15 EC.
TABLE 1
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the invention.
Claims (9)
1. A negative electrode of a sodium ion battery, which is characterized by comprising a negative electrode current collector and a negative electrode active material layer positioned on the surface of the negative electrode current collector, wherein the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a modified binder and a binder; or; the active material of the negative electrode active material layer comprises hard carbon, a conductive agent, a dispersing agent, a modified binder and a binder; the modified adhesive is a conductive adhesive formed by modifying, crosslinking and polymerizing a water-based adhesive through a conductive polymer;
the modified binder is obtained by cross-linking polymerization of a water-based binder and a conductive polymer monomer under the action of an initiator; the water-based binder comprises carboxymethyl cellulose, polyacrylic acid, alginate, chitosan, guar gum, xanthan gum, acacia, and derivatives thereof; the conductive polymer monomer comprises dopamine, aniline, pyrrole, fluorene, pyrene and one of derivatives of the above substances.
2. The negative electrode of the sodium ion battery according to claim 1, wherein the active material comprises the following components in parts by mass: 93-97 parts of hard carbon, 0.5-3 parts of conductive agent, 0-0.5 part of dispersing agent, 1.5-3.5 parts of modified binder and 0.1-2.5 parts of binder.
3. The sodium ion battery anode of claim 1, wherein the hard carbon comprises one or both of biomass-based hard carbon, resin-based hard carbon.
4. The negative electrode of sodium ion battery of claim 1, wherein the conductive agent comprises one or more of carbon black, carbon nanotubes, carbon nanofibers, graphene.
5. The sodium ion battery anode of claim 1, wherein the dispersant comprises carboxymethyl cellulose CMC.
6. The negative electrode of sodium ion battery of claim 1, wherein the binder comprises styrene-butadiene rubber.
7. A negative electrode slurry for preparing the negative electrode of the sodium ion battery according to any one of claims 1 to 6, wherein the negative electrode slurry comprises, by mass, 50 to 60% of active materials, 1.5 to 11.5% of impregnating agents and 38.5 to 48.5% of solvents.
8. The method for producing a negative electrode slurry according to claim 7, comprising the method one or the method two;
the active material of the first method comprises a dispersing agent, and the steps are as follows:
s1, dissolving a dispersing agent in a solvent to obtain a glue solution I, wherein the solid content of the glue solution I is 1-2%;
s2, respectively baking the conductive agent and the hard carbon powder, adding the conductive agent into the hard carbon powder, and stirring to obtain dry powder I;
s3, adding glue once and kneading: adding part of the glue solution I and at least part of the modified binder into the dry powder I, and stirring to obtain slurry II, wherein the solid content of the slurry is 60-70%;
s4, secondary glue adding: adding the residual glue solution I and the residual modified binder into the slurry II, stirring, and adding a solvent to adjust the solid content to obtain a slurry III, wherein the solid content of the slurry is 50-60%;
s5, mixing the binder with the slurry III to obtain slurry IV;
s6, adding the impregnating compound into the slurry IV and stirring to obtain negative electrode slurry;
the active material of the second method does not comprise dispersing agent, and the steps are as follows:
a1, respectively baking the conductive agent and the hard carbon powder, adding the conductive agent into the hard carbon powder, and stirring to obtain dry powder I;
a2, adding at least part of modified binder into the dry powder I, adding solvent, and stirring to obtain slurry II, wherein the solid content of the slurry is 60-70%;
a3, adding the residual modified binder into the slurry II, stirring, and adding a solvent to adjust the solid content to obtain slurry III, wherein the solid content of the slurry is 50-60%;
a4, mixing the binder with the slurry III to obtain slurry IV;
and A5, adding the impregnating compound into the slurry IV, and stirring to obtain the negative electrode slurry.
9. The preparation method according to claim 8, wherein in step S2 of method one, baking is performed under vacuum at 80-160 ℃ for 3-12 hours, ensuring moisture content <500ppm; in the step A1 of the second method, the baking is carried out for 3-12 hours under the vacuum condition at 80-160 ℃ to ensure that the moisture content is less than 500ppm.
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