Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/32—Carbon-based
  • H01G11/38—Carbon pastes or blends; Binders or additives therein
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
  • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for 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
  • Y02E60/13—Energy storage using capacitors

Definitions

• the present invention relates to the field of supercapacitor technology, and in particular to a method for dispersing a composite conductive agent in a lithium ion capacitor electrode slurry.
• Supercapacitors are widely used in the industry because of their high power, long service life and fast charging speed.
• the electrode materials of conventional supercapacitor pads are usually made of carbon-based active materials (such as activated carbon) and binders. Defects with low voltage and low energy density are limited in many applications. Therefore, in order to increase the voltage and energy density of the supercapacitor, the existing supercapacitor electrode sheets are prepared by incorporating a lithium-containing material into the carbon-based active material.
• the electronic conductivity of the lithium-containing material is relatively low. Therefore, it is necessary to add a conductive agent to improve the conductivity during the preparation of the electrode sheet slurry.
• the commonly used conductive agents are mainly granular conductive carbon black, carbon fiber and the like.
• the conventional slurry is prepared by adding an active material, a conductive agent, a binder and an organic solvent to a mixer or a dispersing machine at a certain ratio and stirring for a certain period of time to obtain a pole piece slurry.
• conductive particles such as conductive carbon black are small, they are easily agglomerated and are difficult to disperse in an organic solvent.
• a conductive polymer such as a single conductive carbon black or carbon fiber cannot be used to form a conductive network, and it is difficult to achieve a significant improvement in power. Performance needs. Therefore, in the preparation process of the lithium ion capacitor electrode slurry, how to select a suitable conductive agent and uniformly disperse the conductive agent is of great significance for improving the electrical performance of the lithium ion capacitor.
• CN102496476A Chinese Patent Application Publication No. 2012.06.13 discloses a method for preparing a supercapacitor slurry, which specifically discloses an activated carbon, a conductive agent having an average particle diameter of 1 to 30 ⁇ m and a BET specific surface of 400 to 5000 m 2 /g.
• the binder, solvent and grinding balls are ball-milled into a slurry for supercapacitor electrodes.
• the preparation method comprises the following steps: the activated carbon, the conductive agent, the binder, the solvent and the grinding ball are ball-milled into a slurry for the supercapacitor electrode, and the disadvantage is that the conductive agent cannot be uniformly dispersed and wrapped in the electrode activity by ball milling.
• the surface of the substance (ie, activated carbon), and the ball mill has low working efficiency; in addition, the conductive agent is one or more of acetylene black, conductive carbon black, conductive graphite and carbon fiber, and these carbon-based conductive agents are only embedded in the activated carbon. It does not form a good conductive network structure on the surface of activated carbon, and is conductive to the electrode sheets. The rate of improvement is limited.
• the invention is to solve the problem that the conductive agent in the lithium ion capacitor electrode slurry of the prior art is not easy to disperse and cannot form the conductive network structure effectively, and provides a method for dispersing the composite conductive agent in the lithium ion capacitor electrode slurry.
• the invention has simple process steps, strong operability, and is suitable for industrial production, and can uniformly disperse the composite conductive agent and form a three-dimensional conductive network structure, and the power performance is significantly improved while maintaining a high specific energy of the capacitor.
• a method for dispersing a composite conductive agent in a lithium ion capacitor electrode slurry comprising the steps of:
• the conductive agent is screened by the invention, wherein graphene, carbon nanotubes and conductive carbon black are used as conductive agents, wherein the conductive carbon black is a spherical structure, graphene is a single-layer sheet structure composed of carbon atoms, and the carbon nanotubes are mainly
• the three conductive agents exhibit different structures for forming a plurality of layers of the carbon atoms arranged in a hexagonal shape to the tens of layers. When the three conductive agents are mixed and dispersed, the carbon is centered on the conductive carbon black.
• the two ends of the nanotube are respectively connected to the adjacent conductive carbon black to connect different conductive carbon blacks in series to form a three-dimensional conductive network structure, and the graphene is wrapped on the surface of the conductive carbon black to form composite conductive particles to further improve the conductivity.
• the electrical conductivity of the composite conductive agent of the present invention can be significantly improved compared to a single conductive agent or a conductive agent forming a planar conductive network; the surfactant can improve the surface infiltration of the carbon-based conductive agent in an organic solvent; Performance and dispersion.
• Stepwise dispersion first, the conductive carbon black is mixed with N-methylpyrrolidone and surfactant, and then ultrasonically dispersed, followed by adding carbon nanotubes for the first high-speed dispersion, and finally adding graphene for the second high speed. Disperse it.
• the invention firstly mixes the conductive carbon black with N-methylpyrrolidone and a surfactant, and then ultrasonically disperses to ensure that the conductive carbon black is sufficiently uniformly dispersed, and at the same time supplements the surfactant to improve the dispersion effect, and then sequentially adds carbon nanotubes and graphite.
• the olefin is dispersed at a high speed to form a three-dimensional conductive network structure, and the step of adding the components is extremely important, otherwise a three-dimensional conductive network structure, ultrasonic dispersion and mechanical
• the dispersion process steps are simple, low in cost, and easy to operate.
• the conductive carbon black has a particle diameter of 10 to 50 nm.
• the carbon nanotube has a diameter of 50 to 100 nm.
• the carbon nanotubes are surface-treated carbon nanotubes, and the surface-treated carbon nanotubes are obtained by the following method:
• the carbon nanotubes are added to chlorosulfonic acid, heated to 80-100 ° C for 1 to 3 hours, cooled, filtered, and the filtrate is washed with deionized water until the pH is neutral, and dried under vacuum to obtain swollen carbon nanotubes.
• the chlorosulfonic acid can intercalate and swell the carbon nanotube bundle, and separate the carbon nanotubes from each other and expose the highly reactive amorphous carbon material on the surface thereof, thereby improving the dispersibility and facilitating the amorphous in the subsequent steps.
• the carbon material is sufficiently removed to improve the performance of the carbon nanotubes.
• the non-oxidizing acid (hydrochloric acid) pickling method further removes impurities to obtain pure carbon nanotubes.
• the process conditions of the ultrasonic vibration are: power 4 to 6 W, and the oscillation time is 1 to 2 h.
• prolonging the ultrasonic time will increase the dispersibility of the carbon nanotubes, but at the same time, the length of the carbon nanotubes will be shortened and the defects will be increased, thereby causing a decrease in the electrical conductivity when applied in a battery.
• the conditions of the oscillation are critical.
• the present invention strictly limits the conditions of the ultrasonic vibration, and improves the dispersibility of the carbon nanotubes under the premise of minimizing the damage to the length of the carbon nanotubes, and the obtained carbon nanotubes have high purity.
• the surfactant is linolenic acid, cetyltrimethylammonium bromide, stearic acid, sodium lauryl sulfate or sodium dodecylbenzenesulfonate.
• the surfactant is linolenic acid, cetyltrimethylammonium bromide, stearic acid, sodium lauryl sulfate or sodium dodecylbenzenesulfonate.
• the surfactant is linolenic acid, cetyltrimethylammonium bromide, stearic acid, sodium lauryl sulfate or sodium dodecylbenzenesulfonate.
• the process conditions of the ultrasonic dispersion are: a frequency of 15 to 20 KHz, a power of 200 to 300 W, and an ultrasonic time of 20 to 30 min.
• the present invention performs ultrasonic dispersion time-breaking.
• Hydrogen is introduced into the ground to roll the dispersed material from the bottom to the top to break the transverse standing wave formed by the ultrasonic wave in the dispersed material, so as to prevent the conductive carbon black from accumulating at the nodes, the hydrogen density is small, and the hydrogen will quickly escape after being introduced. Out, the effect is good.
• the first high-speed dispersion and the second high-speed dispersion process parameters are: a rotation speed of 6000 to 10000 r/min, and a dispersion time of 30 to 60 minutes.
• the first high-speed dispersion and the second high-speed dispersion are both carried out under vacuum.
• Dispersion is carried out under vacuum to remove air bubbles and to avoid affecting the dispersion uniformity of the material.
• the present invention has the following beneficial effects:
• the conductive agent is screened, and graphene, carbon nanotubes and conductive carbon black are used as conductive agents, and the three cooperate to form a three-dimensional conductive network structure, which is beneficial to improving conductivity;
• Step-by-step feeding dispersion firstly, the conductive carbon black is mixed with N-methylpyrrolidone and surfactant, and then ultrasonically dispersed for 20 min at a frequency of 15 kHz and a power of 200 W, and hydrogen is introduced into the liquid solution every 1 min during ultrasonic dispersion. Each time the hydrogen gas enters time is 5S, the amount of gas is 0.3m 3 /h, and then the carbon nanotubes are added for the first high-speed dispersion for 60 minutes under the condition of vacuum and rotation speed of 6000r/min, and finally graphene is added in vacuum and The second high-speed dispersion was carried out for 60 min under the condition of a rotational speed of 6000 r/min.
• the conductive carbon black constitutes a composite conductive agent, and is also referred to as N-methylpyrrolidone of 9 times the mass of the composite conductive agent and a surfactant of 15% by mass of the composite conductive agent, and the surfactant is cetyl group.
• Trimethylammonium bromide, stearic acid, and sodium lauryl sulfate are mixed at a mass ratio of 1:1:1.
• the carbon nanotubes are surface-treated carbon nanotubes, which are obtained by the following methods:
• Step-by-step feeding dispersion firstly, the conductive carbon black is mixed with N-methylpyrrolidone and surfactant, and then ultrasonically dispersed for 30 min at a frequency of 20 KHz and a power of 300 W, and hydrogen is introduced into the liquid solution every 3 minutes during ultrasonic dispersion.
• the feed rate is 0.5m 3 /h
• the carbon nanotubes are added for the first high-speed dispersion for 30min under the condition of vacuum and rotation speed of 10000r/min
• graphene is added in vacuum and
• the second high-speed dispersion was carried out for 30 min under the condition of a rotational speed of 10,000 r/min.
• the carbon black constitutes a composite conductive agent, and is also referred to as N-methylpyrrolidone of 7 times the mass of the composite conductive agent and a surfactant of 10% by mass of the composite conductive agent, and the surfactant is linolenic acid, 16
• One or more of alkyltrimethylammonium bromide, stearic acid, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and the carbon nanotubes are surface-treated carbon nanotubes, which pass The following methods are made:
• Step-by-step feeding dispersion firstly, the conductive carbon black is mixed with N-methylpyrrolidone and surfactant, and then ultrasonically dispersed for 25 minutes at a frequency of 18 kHz and a power of 250 W, and hydrogen is introduced into the liquid solution every 2 minutes during ultrasonic dispersion.
• the hydrogen gas inlet time is 8S
• the amount of gas is 0.4m 3 /h
• the carbon nanotubes are added for the first high-speed dispersion for 40 minutes under the condition of vacuum and rotation speed of 8000r/min
• graphene is added in vacuum and
• the second high-speed dispersion was carried out for 40 min under the condition of a rotational speed of 8000 r/min.
• the invention optimizes the formulation of the conductive agent and improves the feeding step and the dispersion mode, the conductive agent has good dispersion effect, and can form a three-dimensional conductive network structure, which is beneficial to improving the conductivity of the super capacitor, and has simple process steps and operability. Strong, suitable for industrial production, has broad application prospects.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing & Machinery (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Electric Double-Layer Capacitors Or The Like (AREA)
• Carbon And Carbon Compounds (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 2014
  • 2014-12-17 CN CN201410779889.8A patent/CN104658757B/zh active Active
• 2015
  • 2015-07-23 AU AU2015100978A patent/AU2015100978A4/en not_active Expired
  • 2015-08-24 WO PCT/CN2015/087919 patent/WO2016095559A1/zh active Application Filing
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