CN116435004A - Halloysite-containing conductive paste, carbon-coated foil and preparation method and application thereof - Google Patents
Halloysite-containing conductive paste, carbon-coated foil and preparation method and application thereof Download PDFInfo
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- CN116435004A CN116435004A CN202310697780.9A CN202310697780A CN116435004A CN 116435004 A CN116435004 A CN 116435004A CN 202310697780 A CN202310697780 A CN 202310697780A CN 116435004 A CN116435004 A CN 116435004A
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- halloysite
- carbon
- conductive paste
- lithium
- coated foil
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 197
- 239000011888 foil Substances 0.000 title claims abstract description 167
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 159
- HPTYUNKZVDYXLP-UHFFFAOYSA-N aluminum;trihydroxy(trihydroxysilyloxy)silane;hydrate Chemical compound O.[Al].[Al].O[Si](O)(O)O[Si](O)(O)O HPTYUNKZVDYXLP-UHFFFAOYSA-N 0.000 title claims abstract description 139
- 229910052621 halloysite Inorganic materials 0.000 title claims abstract description 126
- 238000002360 preparation method Methods 0.000 title abstract description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 117
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 117
- 230000001070 adhesive effect Effects 0.000 claims abstract description 36
- 239000000853 adhesive Substances 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 28
- 239000006258 conductive agent Substances 0.000 claims abstract description 26
- 239000002270 dispersing agent Substances 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 22
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 21
- 238000012986 modification Methods 0.000 claims abstract description 19
- 230000004048 modification Effects 0.000 claims abstract description 19
- 238000005188 flotation Methods 0.000 claims abstract description 12
- 239000002904 solvent Substances 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 11
- 238000009210 therapy by ultrasound Methods 0.000 claims abstract description 11
- 238000002791 soaking Methods 0.000 claims abstract description 9
- 239000000725 suspension Substances 0.000 claims abstract description 8
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 239000000126 substance Substances 0.000 claims abstract description 6
- 239000011248 coating agent Substances 0.000 claims description 45
- 238000000576 coating method Methods 0.000 claims description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000000758 substrate Substances 0.000 claims description 17
- 229910002804 graphite Inorganic materials 0.000 claims description 15
- 239000010439 graphite Substances 0.000 claims description 15
- 229920000058 polyacrylate Polymers 0.000 claims description 14
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 13
- 239000002041 carbon nanotube Substances 0.000 claims description 13
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 12
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 11
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 11
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 11
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- 238000002156 mixing Methods 0.000 claims description 8
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- 229920005749 polyurethane resin Polymers 0.000 claims description 8
- 229910021389 graphene Inorganic materials 0.000 claims description 7
- DLFVBJFMPXGRIB-UHFFFAOYSA-N Acetamide Chemical compound CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 238000007667 floating Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 239000002202 Polyethylene glycol Substances 0.000 claims description 2
- 239000006230 acetylene black Substances 0.000 claims description 2
- 239000002134 carbon nanofiber Substances 0.000 claims description 2
- 239000008367 deionised water Substances 0.000 claims description 2
- 229910021641 deionized water Inorganic materials 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- 229920002554 vinyl polymer Polymers 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 57
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- 238000001816 cooling Methods 0.000 description 17
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- 239000000047 product Substances 0.000 description 12
- 229910052782 aluminium Inorganic materials 0.000 description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 11
- 230000001502 supplementing effect Effects 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 239000003607 modifier Substances 0.000 description 9
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- 239000000706 filtrate Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 230000007774 longterm Effects 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 239000005995 Aluminium silicate Substances 0.000 description 2
- 241000276425 Xiphophorus maculatus Species 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 235000012211 aluminium silicate Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
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- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 2
- 238000006138 lithiation reaction Methods 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
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- 238000001179 sorption measurement Methods 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910001579 aluminosilicate mineral Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
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- 238000004132 cross linking Methods 0.000 description 1
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- 238000003795 desorption Methods 0.000 description 1
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- 239000012535 impurity Substances 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 230000003647 oxidation Effects 0.000 description 1
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Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
-
- 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
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- 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
Abstract
The invention belongs to the technical field of lithium battery materials, and particularly relates to halloysite-containing conductive paste, a carbon-coated foil, a preparation method and application thereof. A conductive paste comprising the following components: a conductive agent, an adhesive, a dispersant, halloysite or a modification thereof, and a solvent; the mass ratio of the conductive agent, the adhesive, the dispersing agent, the halloysite or the modification thereof is (0.018-22): (0.045-22): (0.01-5.5): (0.018-12); the modified halloysite is halloysite loaded with lithium ions in the hollow pipeline; the modified halloysite is obtained through floatation; the flotation process comprises the following steps: and (3) placing halloysite in a lithium-containing solution, soaking, magnetically stirring and performing ultrasonic treatment during soaking to obtain a suspension, taking the middle suspension, and drying to obtain a halloysite modified substance. The lithium battery provided by the invention has good rate capability, high/low temperature discharge efficiency, cycle performance and pole piece stripping force, and has low internal resistance.
Description
Technical Field
The invention belongs to the technical field of lithium battery materials, and particularly relates to halloysite-containing conductive paste, a carbon-coated foil, a preparation method and application thereof.
Background
Along with the rapid development of electronic and electrical technology, the application of lithium batteries is more and more widespread, and higher requirements are also put forward on the performance of the lithium batteries. The lithium battery material has an important influence on the performance of the lithium battery, and in order to improve the overall performance of the lithium battery, the carbon-coated foil has the following advantages: the adhesive force is improved, and the powder falling problem can be solved; the current collector is protected from corrosion and oxidation, and the service life of the battery is prolonged; internal resistance is reduced, and battery capacity is improved; the cycle performance and the multiplying power performance of the battery are improved; improving the consistency of the battery, etc., and is widely used in the field of lithium batteries. However, after the carbon-coated foil is applied to a lithium battery, the requirements of the lithium battery on higher discharge efficiency, cycle performance, pole piece stripping force and the like can not be well met.
In addition, in the first charging process of the lithium ion battery, the organic electrolyte is reduced and decomposed on the surface of a negative electrode such as graphite to form a solid electrolyte phase interface film, so that a large amount of lithium from a positive electrode is permanently consumed, the coulomb efficiency of the first cycle is low, the capacity and the energy density of the lithium ion battery are reduced, and the cycle performance of the battery is reduced. To solve this problem, researchers supplement lithium to the electrode material by a pre-lithiation technique, counteracting irreversible lithium loss caused by the formation of a solid electrolyte interface film (SEI film), to increase the total capacity and energy density of the battery. However, in the pre-lithiation process, if a lithium-containing compound is directly added into the electrode material, the pH value of the electrode material can be changed, and a great amount of impurity ions remain, so that a great potential safety hazard exists; in addition, during prelithiation, special additives are usually arranged in the conventional electrolyte, and the materials participate in the reaction and generate a large amount of gas, so that the battery is inflated, even active gas is generated, and chain side reactions are initiated, which are unfavorable for the discharge performance, the cycle performance, the safety and the like of the battery.
Halloysite is used as an aluminosilicate mineral, and has a one-dimensional nanotube structure with an inner layer and an outer layer, wherein the outer layer is negatively charged, and the inner layer is positively charged. Although halloysite nanotubes do not have electron conductivity, hollow tubes can allow cations to pass through, exhibit strong surface charge-controlled ion transport behavior, can provide channels for ion migration, and can improve the charge transfer performance of a conductive coating primarily relying on electron conduction, to some extent, the mechanical properties and high temperature resistance of the conductive coating. However, if the lithium ion conductive polymer is directly added into an electrode material, the processing difficulty is high, the battery capacity is affected, and the function of directionally transferring lithium ions cannot be achieved when the dosage is small.
Therefore, there is a need to provide a halloysite-containing conductive paste, which is coated on the surface of a carbon-coated foil to form a conductive coating layer, so that the interface performance between a current collector substrate of the carbon-coated foil and the conductive coating layer can be improved, and the lithium supplementing function can be exerted, so that the lithium battery has good rate performance, high-temperature/low-temperature discharge efficiency, cycle performance and pole piece stripping force, and the internal resistance of the lithium battery can be reduced, and the safety of the battery can be improved.
Disclosure of Invention
The present invention is directed to solving one or more of the problems of the prior art and providing at least one of a beneficial choice or creation of conditions. The invention provides a halloysite-containing conductive paste, which is coated on the surface of a carbon-coated foil to form a conductive coating, so that the interface performance between a current collector substrate of the carbon-coated foil and the conductive coating can be improved, and a lithium supplementing function can be exerted, so that a lithium battery has good multiplying power performance, high-temperature/low-temperature discharge efficiency, cycle performance and pole piece stripping force, and the internal resistance of the lithium battery can be reduced, and the safety of the battery can be improved.
The invention is characterized in that: according to the invention, a conductive agent, an adhesive, a dispersing agent, halloysite or a modified product thereof are added at the same time according to a certain proportion, and all the components are synergistic; the conductive agent can construct conductive networks in the conductive coating, and each conductive network enables the constructed network structure to cover the transverse direction and the longitudinal direction of the conductive coating through the connection of the adhesive and the dispersion effect of the dispersing agent; meanwhile, strong anchor point effect can be formed between halloysite or the modified product thereof and the conductive agent, so that the mechanical strength of the conductive coating and the adhesive force on the current collector substrate are improved, and further the battery performance can be improved. In addition, by using a halloysite special hollow pipeline, the halloysite is placed in a lithium-containing solution for soaking modification to obtain a halloysite modified substance, so that the hollow pipeline adsorbs a large amount of lithium ions, and the large amount of lithium ions occupy a large amount of space, and the introduction of a solvent in the aqueous slurry into a battery can be avoided; the modified halloysite has the functions of slow release and buffering on lithium ions and electrolyte, and can realize good lithium supplementing function, so that the cycle life, discharge efficiency, rate performance and the like of the battery are improved. When the conductive paste is applied to the carbon-coated foil, the interface performance between the conductive coating and the current collector substrate of the carbon-coated foil can be improved, so that the lithium battery has good rate capability, high-temperature/low-temperature discharge efficiency, cycle performance and pole piece stripping force, and the internal resistance of the lithium battery can be reduced, and the safety of the battery can be improved.
Accordingly, a first aspect of the present invention provides a halloysite-containing conductive paste.
Specifically, the halloysite-containing conductive paste comprises the following components: a conductive agent, an adhesive, a dispersant, halloysite or a modification thereof, and a solvent;
the mass ratio of the conductive agent, the adhesive, the dispersing agent, the halloysite or the modification thereof is (0.018-22): (0.045-22): (0.01-5.5): (0.018-12);
the modified halloysite is halloysite loaded with lithium ions in the hollow pipeline;
the modified halloysite is obtained by floating halloysite through a lithium-containing solution with a concentration gradient;
the flotation process comprises the following steps:
placing halloysite in a lithium-containing solution, soaking, magnetically stirring and performing ultrasonic treatment in the soaking process to obtain a suspension, and then taking a middle suspension and drying to obtain a halloysite modified substance;
the concentration of the lithium-containing solution is 0.01-0.1mol/L.
Preferably, the mass ratio of the conductive agent, the adhesive, the dispersant, the halloysite or the modification thereof is (0.02-20): (0.05-20): (0.01-5): (0.02-10).
Preferably, the mass ratio of the conductive agent, the adhesive, the dispersing agent, the halloysite or the modified product thereof and the solvent is (0.02-20): (0.05-20): (0.01-5): (0.02-10): (45-99.9).
Specifically, because halloysite has special lumen structural characteristics, the outer layer of halloysite is negatively charged, the inner layer of halloysite is positively charged, and a hollow pipeline can provide a channel for ion migration, so that the ion conductivity can be improved; meanwhile, halloysite is used as an inorganic material additive, so that the film surface property and the structural property of the carbon-coated foil conductive coating can be improved, the mechanical property, the thermal stability and the roughness are improved, and the safety performance and the cycle life of the battery are further improved. In addition, halloysite also has enough specific surface area and adsorption strength, can absorb byproducts in the battery circulation process, can store a certain amount of free lithium ions in the long-term circulation process, plays a role in supplementing lithium, can prevent lithium from separating out, reduces the steric hindrance of deintercalation lithium, and enhances the circulation performance of a lithium battery. In addition, strong anchor point effect can be formed between halloysite and the conductive agent, so that the halloysite can participate in a conductive network formed by the conductive agent, the functions of the halloysite can be fully utilized and enhanced, the mechanical strength of the conductive coating and the adhesive force on a current collector substrate are improved, and further the battery performance can be improved. After the halloysite is modified, the modified halloysite still has the above characteristics.
Specifically, the halloysite hollow pipeline has enough space, the halloysite is placed in the lithium-containing solution for full soaking to realize modification of the halloysite, so that a large amount of dissociable lithium ions are adsorbed or combined in the hollow pipeline, the halloysite hollow pipeline can be used as a place for buffering and slowly releasing lithium ions and electrolyte, consumption of the electrolyte in long-term battery circulation can be counteracted in the battery circulation process, and the battery can be used in different temperature environments in a targeted manner, so that the working range of the battery is widened. In addition, the modified halloysite is added into the conductive slurry, so that the lithium battery can achieve the effect of supplementing lithium in the first charge and discharge process, and the capacity, the cycle performance, the safety and the energy density of the battery are improved.
Preferably, the conductive paste is a stable dispersion.
Preferably, the viscosity of the conductive paste is 100-3000cps at 25 ℃; the solid content in the conductive paste is 0.1% -55%.
Further preferably, the viscosity of the conductive paste is 150 to 2500cps at 25 ℃; the solid content in the conductive paste is 0.5% -50%.
Preferably, the halloysite has a particle size D50:0.45-22 mu m, and the slenderness ratio of the halloysite is 6-17.
Further preferably, the halloysite has a particle size D50:0.5-20 mu m, wherein the slenderness ratio of the halloysite is 8-15.
Preferably, the conductive agent includes at least one of graphite, carbon black, acetylene black, carbon nanotubes, graphene, and carbon nanofibers.
Preferably, when the conductive agent is graphite, carbon black, carbon nanotubes or graphene; the mass ratio of the graphite, the carbon black, the carbon nano tube or the graphene is (17-40): (55-85): (0.8-5.5).
Further preferably, the mass ratio of the graphite, carbon black, carbon nanotubes or graphene is (19-35): (60-80): (1-5).
Specifically, when the conductive agent is graphite, carbon black, carbon nanotubes or graphene, the conductive network formed between the conductive agents is a dot (carbon black) -line (carbon nanotubes or graphene) -surface (graphite) structure, and the structure can improve the mechanical strength, conductivity and adhesion effect of the whole conductive coating on the carbon foil-coated current collector substrate, so that the lithium battery has good rate capability, high-temperature/low-temperature discharge efficiency, cycle performance and pole piece stripping force. In addition, halloysite or modified products thereof and granular carbon black form a strong anchor point effect on the surface of graphite, so that the mechanical strength of the conductive coating and the adhesive force on a current collector substrate are further improved, and further the battery performance can be improved.
Preferably, the adhesive includes at least one of an acrylic polymer-based adhesive, a polyolefin resin-based adhesive, a polyurethane resin-based adhesive, a polyacrylonitrile resin-based adhesive, and an epoxy resin-based adhesive; the dispersing agent comprises at least one of polyvinylpyrrolidone, polyethylene glycol, polyvinyl acetamide and alkylphenol ethoxylates; the solvent comprises at least one of deionized water, ethanol and isopropanol.
Preferably, the acrylic polymer-based binder includes at least one of an acrylic polymer and a modified acrylic polymer; the polyolefin resin binder comprises at least one of polyolefin resin and modified polyolefin resin; the polyurethane resin binder comprises at least one of polyurethane resin and modified polyurethane resin; the polyacrylonitrile resin binder comprises at least one of polyacrylonitrile resin and modified polyacrylonitrile resin; the epoxy resin adhesive comprises at least one of epoxy resin and modified epoxy resin.
Preferably, the modified acrylic polymer, the modified polyolefin resin, the modified polyurethane resin, the modified polyacrylonitrile resin and the modified epoxy resin are obtained by modifying the acrylic polymer, the polyolefin resin, the polyurethane resin, the polyacrylonitrile resin and the epoxy resin by a modification method.
Preferably, the modification method comprises any one of copolymerization, grafting, crosslinking and blending.
Specifically, the purpose of modifying acrylic polymer, polyolefin resin, polyurethane resin, polyacrylonitrile resin and epoxy resin is to improve the dielectric constant of the resin, enhance toughness, reduce internal stress and improve high temperature resistance.
Preferably, the modified halloysite is obtained by repeatedly floating halloysite in a lithium-containing solution having a concentration gradient.
Preferably, the concentration of the lithium-containing solution is 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, respectively.
In particular, in the process of flotation of lithium-containing solution, as the apparent concentration of lithium ions in halloysite hollow pipelines is gradually increased,
the concentration of the lithium-containing solution also needs to be increased, so the lithium-containing solution is used in sequence from low to high according to a certain concentration gradient.
Specifically, the concentration of the lithium-containing solution is not limited to the above-described selection, and may be appropriately selected according to the circumstances.
Specifically, the main functions of flotation of lithium-containing solutions are: (1) The hollow pipeline space of halloysite is enabled to absorb enough lithium ions through repeated flotation, so that the problem of lithium ion desorption of halloysite in water-based slurry is solved, and the slow release amount can be controlled; (2) Because a large amount of space in the hollow pipeline is occupied by lithium ions, excessive moisture is prevented from being introduced into a battery system, and the conductive energy between the conductive coating and other interfaces can be improved on the premise of not affecting the performance of the carbon-coated foil and the battery; (3) Halloysite with uniform particle size and length-diameter ratio is screened out, and the consistency performance of the conductive slurry is improved.
Preferably, the lithium-containing solution is selected from the group consisting of LiOH solution, li 2 SO 4 Solution, liNO 3 At least one of the solutions.
Preferably, the rotating speed of the magnetic stirring is 450-900rpm, and the time of the magnetic stirring is 18-45min.
Further preferably, the rotation speed of the magnetic stirring is 500-800rpm, and the time of the magnetic stirring is 20-40min.
Preferably, the power of the ultrasonic treatment is 45-90W, the frequency of the ultrasonic treatment is 18-33KHz, and the time of the ultrasonic treatment is 18-45min.
Further preferably, the power of the ultrasonic treatment is 50-80W, the frequency of the ultrasonic treatment is 20-30KHz, and the time of the ultrasonic treatment is 20-40min.
Preferably, the drying is performed by baking; the drying temperature is 50-70 ℃, and the drying time is 20-40min.
Further preferably, the drying temperature is 55-65 ℃ and the drying time is 25-35min.
Still more preferably, the temperature of the drying is 60 ℃, and the time of the drying is 30min.
A second aspect of the present invention provides a method for preparing the halloysite-containing conductive paste according to the first aspect of the present invention.
Specifically, the preparation method of the halloysite-containing conductive paste comprises the following steps:
and mixing the halloysite or the modified product thereof with the conductive agent, the adhesive, the dispersing agent and the solvent to prepare the conductive paste.
Preferably, the conductive paste is prepared by mixing, dispersing and sanding the conductive agent, the adhesive, the dispersing agent and the solvent, and then adding the halloysite or the modified product thereof and the dispersing agent.
Preferably, the conductive agent, the adhesive and the dispersing agent are uniformly mixed in the solvent.
Preferably, the dispersion is carried out under vacuum conditions and water-cooled conditions.
Preferably, the vacuum degree of the vacuum condition is 0.07-0.095MPa; the temperature of the water cooling condition is 8-18 ℃.
Further preferably, the vacuum degree of the vacuum condition is 0.08-0.09MPa; the temperature of the water cooling condition is 10-15 ℃.
Preferably, the shear rate of the dispersion is 10-25m/s and the time of the dispersion is 2-5h.
Further preferably, the shear rate of the dispersion is 12-20m/s and the time of the dispersion is 2.5-4h.
Preferably, after the dispersion, filtering is carried out firstly, and then the filtrate is taken and sanded; the filtering is performed by a filter screen.
Preferably, the rotational speed of the sanding is 600-10000rpm, and the time of the sanding is 1-5h.
Further preferably, the rotational speed of the sanding is 2000-5000rpm and the time of the sanding is 2-4 hours.
Specifically, the sanding liquid is obtained after sanding.
Preferably, halloysite or a modified product thereof and a dispersing agent are added into the sanding liquid, and dispersion is carried out under vacuum condition and water cooling condition, so that the conductive paste is prepared.
Preferably, the vacuum degree of the vacuum condition is 0.07-0.095MPa; the temperature of the water cooling condition is 8-18 ℃.
Further preferably, the vacuum degree of the vacuum condition is 0.08-0.09MPa; the temperature of the water cooling condition is 10-15 ℃.
Preferably, the shear rate of the dispersion is 10-25m/s and the time of the dispersion is 2-5h.
Further preferably, the shear rate of the dispersion is 12-20m/s and the time of the dispersion is 2.5-4h.
A third aspect of the invention provides a carbon-coated foil.
Specifically, a carbon-coated foil comprises a current collector substrate and a coating formed by the conductive paste according to the first aspect of the invention.
A fourth aspect of the present invention provides a method for producing a carbon-coated foil according to the third aspect of the present invention.
Specifically, the preparation method of the carbon-coated foil comprises the following steps:
and coating the conductive slurry on the surface of the current collector substrate, and curing to obtain the carbon-coated foil.
Preferably, the current collector substrate is selected from any one of aluminum foil and copper foil.
Preferably, the coating mode is selected from any one of gravure printing, relief printing, screen printing and lithography.
Preferably, the coating speed is 30-260m/min.
Further preferably, the coating speed is 60-220m/min.
Preferably, the curing is performed by baking.
Preferably, the temperature of the curing is 90-220 ℃.
Further preferably, the temperature of the curing is 100-200 ℃.
Specifically, the curing time is reasonably selected according to the actual situation.
Specifically, after curing, a loose and porous conductive coating is obtained on the carbon-coated foil.
Preferably, the thickness of the conductive coating is 0.5-1.0 [ mu ] m.
Further preferably, the thickness of the conductive coating is 0.6-0.9 [ mu ] m.
A fifth aspect of the present invention provides a use of the conductive paste according to the first aspect of the present invention and/or the carbon coated foil according to the third aspect of the present invention in the field of lithium batteries.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
(1) According to the invention, a conductive agent, an adhesive, a dispersing agent, halloysite or a modified product thereof are added at the same time according to a certain proportion, and all the components are synergistic; the conductive agent can construct conductive networks in the conductive coating, and each conductive network enables the constructed network structure to cover the transverse direction and the longitudinal direction of the conductive coating through the connection of the adhesive and the dispersion effect of the dispersing agent. In addition, halloysite or a modified product thereof and the surface of the conductive agent can form a strong anchor point effect, so that the conductive coating has good mechanical strength and adhesive force on a current collector substrate, the interface performance between the conductive coating and the current collector substrate coated with the carbon foil can be improved when the prepared conductive slurry is applied to the carbon foil, and further, the lithium battery has good rate capability, high-temperature/low-temperature discharge efficiency, cycle performance and pole piece stripping force, and the internal resistance of the lithium battery can be reduced and the safety can be improved.
(2) The halloysite disclosed by the invention has enough specific surface area and adsorption strength, can absorb byproducts in the battery circulation process, can store a certain amount of free lithium ions in the long-term circulation process, plays a role in supplementing lithium, can prevent lithium from separating out, reduces the steric hindrance of deintercalation lithium, and enhances the circulation performance of a lithium battery.
(3) The halloysite hollow pipeline has enough space, and the halloysite hollow pipeline is modified to absorb or combine a large amount of dissociable lithium ions, so that the lithium supplementing function can be exerted, the halloysite hollow pipeline can be used as a place for buffering and slowly releasing lithium ions and electrolyte, the consumption of the electrolyte in the long-term circulation of the battery can be counteracted in the battery circulation process, the use of the battery in different temperature environments can be correspondingly dealt with, and the working range of the battery can be widened.
(4) According to the invention, the halloysite is placed in the lithium-containing solution for repeated soaking, so that the modification can be finished, the modification process is simple, the operation is easy, and the cost is saved.
Drawings
FIG. 1 is an SEM image of a carbon-coated aluminum foil of example 1 of a carbon-coated foil of the present invention;
FIG. 2 is a bar graph of peel force for lithium battery pole pieces of carbon-coated foil examples 1-4 and carbon-coated foil comparative examples 1-2 of the present invention;
FIG. 3 is a bar graph of the internal resistance of lithium batteries of examples 1-4 of carbon-coated foils of the present invention and comparative examples 1-2 of carbon-coated foils;
FIG. 4 is a graph showing the discharge efficiency at 60℃for 1C of the lithium batteries of examples 1-4 and comparative examples 1-2 of the carbon-coated foil of the present invention;
FIG. 5 is a graph showing the discharge efficiency at-20deg.C for the lithium cells of examples 1-4 and comparative examples 1-2 of the carbon-coated foil of the present invention;
FIG. 6 is a graph showing the discharge efficiency at 20℃ at 10C for the lithium batteries of examples 1-4 and comparative examples 1-2 of the carbon-coated foil of the present invention;
fig. 7 is a graph showing the capacity retention rate of the lithium batteries of examples 1 to 4 and comparative examples 1 to 2 coated with carbon foil according to the present invention after cycling at 20 c for 1200 times.
Detailed Description
In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples will be presented. It should be noted that the following examples do not limit the scope of the invention.
The starting materials, reagents or apparatus used in the following examples are all available from conventional commercial sources or may be obtained by methods known in the art unless otherwise specified.
The preparation process of the halloysite modifier in the conductive paste embodiments 1-3 comprises the following steps:
(1) Adding 100g of halloysite with the length-diameter ratio of 6-17 into 0.01mol/L LiOH solution, scattering halloysite agglomerates through magnetic stirring, wherein the rotation speed of the magnetic stirring is 500rpm, the time of the magnetic stirring is 20min, simultaneously carrying out ultrasonic treatment, the power of the ultrasonic treatment is 70W, the frequency is 25KHz, the time is 30min, obtaining halloysite suspension, immediately selecting milky suspension with suspended middle part, and drying at 60 ℃ for 30min, thus obtaining halloysite after primary flotation;
(2) Adding halloysite obtained in the step (1) into 0.02mol/L LiOH solution, and then repeating the flotation process of the step (1) to obtain halloysite subjected to secondary flotation;
(3) Adding halloysite obtained in the step (2) into 0.05mol/L LiOH solution, and then repeating the flotation process of the step (1) to obtain halloysite subjected to third flotation;
(4) Adding halloysite obtained in the step (3) into 0.10mol/L LiOH solution, and repeating the flotation process of the step (1) to obtain the halloysite modified product required by the conductive paste examples 1-3.
Conductive paste example 1
A halloysite-containing conductive paste comprises 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer, 5g of polyvinylpyrrolidone, 20g of halloysite modifier and 775g of pure water.
A preparation method of halloysite-containing conductive paste comprises the following steps:
(1) Adding 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer and 4g of polyvinylpyrrolidone into 775g of pure water gradually and slowly under the stirring speed of 500rpm/min, and uniformly mixing; then vacuumizing, introducing cooling water for water cooling, and dispersing under the vacuum and water cooling conditions; the vacuum degree is 0.09MPa, the temperature of a dispersion system is 12 ℃, the shearing speed of dispersion is 18m/s, and the dispersion time is 3 hours, so that a dispersion liquid is obtained;
(2) Filtering the dispersion liquid obtained in the step (1) by using a filter screen, and taking the filtrate for sanding, wherein the sanding speed is 3200rpm, and the sanding time is 3 hours, so as to obtain a sanding liquid;
(3) And (3) sequentially adding 20g of halloysite modified substance and 1g of polyvinylpyrrolidone into the grinding liquid obtained in the step (2), and dispersing under vacuum and water cooling conditions, wherein the vacuum condition, the water cooling condition and the dispersing process are the same as those in the step (1), so as to obtain the conductive slurry.
Conductive paste example 2
A halloysite-containing conductive paste comprises 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer, 5g of polyvinylpyrrolidone, 50g of halloysite modifier and 745g of pure water.
A preparation method of halloysite-containing conductive paste comprises the following steps:
(1) Adding 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer and 4g of polyvinylpyrrolidone into 745g of pure water gradually and slowly under the stirring speed of 500rpm/min, and uniformly mixing; then vacuumizing, introducing cooling water for water cooling, and dispersing under the vacuum and water cooling conditions; the vacuum degree is 0.09MPa, the temperature of a dispersion system is 12 ℃, the shearing speed of dispersion is 18m/s, and the dispersion time is 3 hours, so that a dispersion liquid is obtained;
(2) Filtering the dispersion liquid obtained in the step (1) by using a filter screen, and taking the filtrate for sanding, wherein the sanding speed is 3200rpm, and the sanding time is 3 hours, so as to obtain a sanding liquid;
(3) Adding 50g of halloysite modifier and 1g of polyvinylpyrrolidone into the grinding liquid obtained in the step (2) in sequence, and dispersing under vacuum and water cooling conditions, wherein the vacuum condition, the water cooling condition and the dispersing process are the same as those in the step (1), so as to obtain the conductive slurry.
Conductive paste example 3
A halloysite-containing conductive paste comprises 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer, 5g of polyvinylpyrrolidone, 100g of halloysite modifier and 695g of pure water.
A preparation method of halloysite-containing conductive paste comprises the following steps:
(1) Adding 70g of carbon black, 27g of graphite, 3g of carbon nano tube, 100g of acrylic polymer and 4g of polyvinylpyrrolidone into 695g of pure water gradually and slowly under the stirring speed of 500rpm/min, and uniformly mixing; then vacuumizing, introducing cooling water for water cooling, and dispersing under the vacuum and water cooling conditions; the vacuum degree is 0.09MPa, the temperature of a dispersion system is 12 ℃, the shearing speed of dispersion is 18m/s, and the dispersion time is 3 hours, so that a dispersion liquid is obtained;
(2) Filtering the dispersion liquid obtained in the step (1) by using a filter screen, and taking the filtrate for sanding, wherein the sanding speed is 3200rpm, and the sanding time is 3 hours, so as to obtain a sanding liquid;
(3) And (3) adding 100g of halloysite modified substance and 1g of polyvinylpyrrolidone into the grinding liquid obtained in the step (2) in sequence, and dispersing under vacuum and water cooling conditions, wherein the vacuum condition, the water cooling condition and the dispersing process are the same as those in the step (1), so as to obtain the conductive slurry.
Conductive paste example 4
Conductive paste example 4 differs from conductive paste example 1 only in that conductive paste example 4 uses equal amounts of halloysite instead of halloysite modification, and is otherwise identical to conductive paste example 1.
Carbon coated foil example 1
A carbon coated foil comprising an aluminum foil and a coating of conductive paste example 1.
A method for preparing a carbon-coated foil, comprising the steps of:
and coating the conductive paste on the surface of the aluminum foil at a coating speed of 80m/min by adopting a gravure printing coating mode, and then baking and curing at 100 ℃ to obtain the loose and porous carbon-coated foil with the thickness of 0.8 mu m.
Carbon coated foil example 2
Carbon coated foil example 2 differs from carbon coated foil example 1 only in that the carbon coated foil of carbon coated foil example 2 includes a coating of aluminum foil and conductive paste of conductive paste example 2, otherwise identical to carbon coated foil example 1.
Carbon coated foil example 3
Carbon coated foil example 3 differs from carbon coated foil example 1 only in that the carbon coated foil of carbon coated foil example 3 includes a coating of aluminum foil and conductive paste of conductive paste example 3, otherwise identical to carbon coated foil example 1.
Carbon coated foil example 4
Carbon coated foil example 4 differs from carbon coated foil example 1 only in that the carbon coated foil of carbon coated foil example 4 includes a coating of aluminum foil and conductive paste of conductive paste example 4, otherwise identical to carbon coated foil example 1.
Conductive paste comparative example 1
In comparative example 1 of the electroconductive paste, halloysite was not added, nor was a modified halloysite added.
Conductive paste comparative example 1 differs from conductive paste example 1 only in that conductive paste comparative example 1 does not have a halloysite modification added thereto, and otherwise is the same as conductive paste example 1.
Conductive paste comparative example 1 differs from conductive paste example 4 only in that halloysite is not added to conductive paste comparative example 1, and the other is the same as conductive paste example 4.
Conductive paste comparative example 2
Conductive paste comparative example 2 differs from conductive paste example 1 only in that the conductive paste of conductive paste comparative example 2 uses an equivalent amount of platy kaolin instead of halloysite modification, otherwise identical to conductive paste example 1.
Carbon coated foil comparative example 1
Carbon coated foil comparative example 1 differs from carbon coated foil example 1 only in that the carbon coated foil of carbon coated foil comparative example 1 includes an aluminum foil and a coating formed from the conductive paste of conductive paste comparative example 1, otherwise identical to carbon coated foil example 1.
Carbon coated foil comparative example 1 and carbon coated foil example 4 differ only in that the carbon coated foil of carbon coated foil comparative example 1 includes an aluminum foil and a coating formed from the conductive paste of conductive paste comparative example 1, otherwise identical to carbon coated foil example 4.
Carbon coated foil comparative example 2
Carbon coated foil comparative example 2 differs from carbon coated foil example 1 only in that the carbon coated foil of carbon coated foil comparative example 2 includes a coating formed of aluminum foil and conductive paste of conductive paste comparative example 2, otherwise identical to carbon coated foil example 1.
Performance testing
SEM test
SEM testing was performed on the carbon-coated foil prepared in example 1 of the carbon-coated foil, as shown in fig. 1. As can be seen from fig. 1, the conductive coating layer is uniformly covered on the surface of the metal aluminum foil, so that the main components are staggered.
Battery performance test
Carbon-coated foils the carbon-coated foils of examples 1-4 and comparative examples 1-2 were prepared as soft pack lithium batteries, respectively. Wherein the positive electrode is 622 ternary, the negative electrode is graphite, and the preparation process of the soft-package lithium battery adopts a conventional preparation process. And then performance testing is carried out on the prepared soft package lithium battery, testing standards are carried out according to GB/T31484-2015 and GB/T31467.1-2015, and testing results are shown in table 1.
Table 1: battery performance test results
As can be seen from Table 1, the soft-pack lithium batteries prepared from the carbon-coated foils of examples 1-4 of the carbon-coated foils of the present invention have good capacity retention, discharge efficiency, rate capability, pole piece peeling force, and lower internal resistance. The conductive paste of the embodiment 1-4 of the conductive paste is used as a conductive coating to be coated on a current collector substrate coated with carbon foil, so that the interface performance between the conductive coating and the current collector substrate coated with carbon foil can be improved, the lithium supplementing function can be exerted, the rate capability, the cycle performance and the pole piece stripping performance of a lithium battery are further improved, the internal resistance of the lithium battery is reduced, good discharge efficiency is achieved at different temperatures of high temperature and low temperature, and the working range of the battery is widened. In addition, as can be seen from examples 1 and 4 of the carbon-coated foil, the rate capability, the cycle performance and the pole piece stripping performance of the lithium battery of example 1 of the carbon-coated foil are superior to those of example 4 of the carbon-coated foil at different temperatures, and the internal resistance of the lithium battery is lower than that of example 4 of the carbon-coated foil, which shows that modifying halloysite to load a large amount of lithium ions in a hollow pipeline is helpful for further improving the comprehensive performance of the lithium battery.
The only difference between the carbon-coated foil comparative example 1 and the carbon-coated foil example 1 is that the conductive coating layer of the carbon-coated foil comparative example 1 does not contain halloysite modifier, and as a result, the capacity retention rate, discharge efficiency at different temperatures, and pole piece peeling force of the lithium battery prepared by the carbon-coated foil comparative example 1 are lower than those of the carbon-coated foil example 1, and the internal resistance of the battery is higher than that of the carbon-coated foil example 1. The overall performance of the carbon-coated comparative example 1 lithium battery was inferior to that of the carbon-coated example 1 lithium battery. The modified halloysite is applied to the conductive coating, so that the interface performance between the conductive coating and the current collector substrate coated with the carbon foil can be improved, the lithium supplementing function can be exerted, the internal resistance of the battery is further reduced, and the comprehensive performance of the lithium battery is improved.
The only difference between carbon-coated foil comparative example 1 and carbon-coated foil example 4 is that the conductive coating of the carbon-coated foil of carbon-coated foil comparative example 1 does not contain halloysite, and as a result, the overall performance of the lithium battery prepared by carbon-coated foil comparative example 1 is inferior to that of the lithium battery of carbon-coated foil example 4. The halloysite is applied to the conductive coating, so that the comprehensive performance of the lithium battery is improved.
The only difference between carbon-coated foil comparative example 2 and carbon-coated foil example 1 is that the carbon-coated foil of carbon-coated foil comparative example 2 has an equivalent amount of platy kaolin in the conductive coating instead of halloysite modification, and this has the result that the overall performance of the lithium battery of carbon-coated foil comparative example 2 is inferior to that of the carbon-coated foil example 1. The modified halloysite has irreplaceable effects in the invention, and can improve the interface performance between the conductive coating and the current collector substrate coated with the carbon foil, and can play a role in supplementing lithium, thereby reducing the internal resistance of the battery and improving the comprehensive performances of the lithium battery such as multiplying power performance, cycle performance, discharge efficiency and the like when being applied to the conductive coating.
Pole piece peel force bar graphs for the lithium batteries of carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2 are shown in fig. 2. As can be seen from fig. 2, the lithium battery of the present invention has good pole piece peeling force, and it is also illustrated that the addition of halloysite or a modification of halloysite helps to improve the adhesive property of the pole piece.
Carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2, are shown in fig. 3 as a bar graph of internal resistance of lithium batteries. As can be seen from fig. 3, the internal resistance of the lithium batteries of examples 1 to 4 of the carbon-coated foil of the present invention was lower than that of the lithium batteries of comparative examples 1 to 2 of the carbon-coated foil, and it was also demonstrated that the addition of halloysite or a modification of halloysite could reduce the internal resistance of the batteries.
Carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2 lithium batteries have a 1C discharge efficiency curve at 60C as shown in fig. 4. In the graph of fig. 4, carbon-coated foil example 3, carbon-coated foil example 2, carbon-coated foil example 1, carbon-coated foil example 4, carbon-coated foil comparative example 1, and carbon-coated foil comparative example 2 are shown in this order from top to bottom. It can be seen that the carbon-coated foil examples 1 to 4 lithium batteries have a discharge efficiency of 1C at 60C superior to that of the carbon-coated foil comparative example 1 and the carbon-coated foil comparative example 2 as a whole, indicating that the addition of halloysite or a modification of halloysite to the conductive paste can improve the high-temperature discharge efficiency of the lithium battery, and the carbon-coated foil example 1 lithium battery has a higher high-temperature discharge efficiency than that of the halloysite-added lithium battery of the carbon-coated foil example 4 due to the addition of the modification of halloysite.
Carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2 lithium batteries were subjected to a-20C discharge efficiency curve as shown in fig. 5. As can be seen from fig. 5, the discharge efficiency curves of the carbon-coated foil examples 1 to 4 lithium batteries are located above the discharge efficiency curves of the carbon-coated foil comparative examples 1 to 2 lithium batteries as a whole, which shows that the-20 ℃ and 1C discharge efficiency of the carbon-coated foil examples 1 to 4 lithium batteries are superior to those of the carbon-coated foil comparative examples 1 and 2 as a whole, and also shows that the addition of halloysite or a halloysite modifier to the conductive paste can improve the low-temperature discharge efficiency of the lithium batteries, and that the low-temperature discharge efficiency of the carbon-coated foil example 1 lithium batteries is superior to that of the carbon-coated foil example 4 lithium batteries.
Carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2 lithium batteries were rated at 10C at 20C with a discharge efficiency curve as shown in fig. 6. In the graph of fig. 6, the graphs of the carbon-coated foil example 3, the carbon-coated foil example 1, the carbon-coated foil example 4, the carbon-coated foil comparative example 1, and the carbon-coated foil comparative example 2 are sequentially shown from top to bottom, wherein the graphs of the carbon-coated foil example 2 and the carbon-coated foil example 3 are substantially coincident. The ratio discharge efficiency curves of the carbon-coated foil examples 1-4 lithium batteries are shown to be positioned above the ratio discharge efficiency curves of the carbon-coated foil comparative examples 1-2 lithium batteries as a whole, the ratio discharge efficiency of the carbon-coated foil examples 1-4 lithium batteries at 20 ℃ and 10C is shown to be superior to that of the carbon-coated foil comparative examples 1 and 2 as a whole, and the ratio performance of the lithium batteries with halloysite added to the conductive paste can be improved by adding halloysite or a halloysite modified product, and the ratio performance of the lithium batteries with halloysite added to the lithium batteries with halloysite modified product is better than that of the lithium batteries with halloysite added to the lithium batteries.
Carbon coated foil examples 1-4, carbon coated foil comparative examples 1-2 lithium batteries were cycled 1200 times at 20 c for capacity retention curves as shown in fig. 7. In the graph of fig. 7, carbon-coated foil example 3, carbon-coated foil example 2, carbon-coated foil example 1, carbon-coated foil example 4, carbon-coated foil comparative example 1, and carbon-coated foil comparative example 2 are shown in this order from top to bottom. As can be seen from fig. 7, the 20 ℃ cycle capacity retention of the carbon coated foil example 1-4 lithium batteries is higher than the carbon coated foil comparative examples 1-2, with longer cycle life. It was demonstrated that the cycle performance of the lithium battery was improved when halloysite or a halloysite modifier was added to the conductive paste, and the capacity retention rate of the lithium battery coated with the halloysite modifier of example 1 was slightly better than that of the lithium battery coated with the halloysite of example 4.
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention.
Claims (10)
1. The conductive paste is characterized by comprising the following components: a conductive agent, an adhesive, a dispersant, halloysite or a modification thereof, and a solvent;
the mass ratio of the conductive agent, the adhesive, the dispersing agent, the halloysite or the modification thereof is (0.018-22): (0.045-22): (0.01-5.5): (0.018-12);
the modified halloysite is halloysite loaded with lithium ions in the hollow pipeline;
the modified halloysite is obtained by floating halloysite through a lithium-containing solution with a concentration gradient;
the flotation process comprises the following steps:
placing halloysite in a lithium-containing solution, soaking, magnetically stirring and performing ultrasonic treatment in the soaking process to obtain a suspension, and then taking a middle suspension and drying to obtain a halloysite modified substance;
the concentration of the lithium-containing solution is 0.01-0.1mol/L.
2. The conductive paste according to claim 1, wherein the viscosity of the conductive paste is 100-3000cps at 25 ℃; the solid content in the conductive paste is 0.1% -55%.
3. The electroconductive paste according to claim 1, wherein the halloysite has a particle size D50:0.45-22 mu m, and the slenderness ratio of the halloysite is 6-17.
4. The conductive paste of claim 1, wherein the conductive agent comprises at least one of graphite, carbon black, acetylene black, carbon nanotubes, graphene, and carbon nanofibers.
5. The conductive paste according to claim 1, wherein the adhesive comprises at least one of an acrylic polymer-based adhesive, a polyolefin resin-based adhesive, a polyurethane resin-based adhesive, a polyacrylonitrile resin-based adhesive, and an epoxy resin-based adhesive; the dispersing agent comprises at least one of polyvinylpyrrolidone, polyethylene glycol, polyvinyl acetamide and alkylphenol ethoxylates; the solvent comprises at least one of deionized water, ethanol and isopropanol.
6. The conductive paste as claimed in claim 1, wherein the lithium-containing solution is selected from the group consisting of LiOH solution, li 2 SO 4 Solution, liNO 3 At least one of the solutions.
7. The method for preparing a conductive paste according to any one of claims 1 to 6, comprising the steps of:
and mixing the halloysite or the modified product thereof with the conductive agent, the adhesive, the dispersing agent and the solvent to prepare the conductive paste.
8. The method according to claim 7, wherein the conductive paste is prepared by mixing, dispersing and sanding the conductive agent, the adhesive, the dispersant and the solvent, and then adding the halloysite or the modified product thereof and the dispersant.
9. A carbon-coated foil comprising a current collector substrate and a coating formed from the conductive paste of any one of claims 1-6.
10. Use of the electroconductive paste according to any one of claims 1-6 and/or the carbon-coated foil according to claim 9 in the field of lithium batteries.
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