WO2021184222A1 - 一种基于石墨烯量子点及其衍生物的导电涂层材料及其应用 - Google Patents

一种基于石墨烯量子点及其衍生物的导电涂层材料及其应用 Download PDF

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WO2021184222A1
WO2021184222A1 PCT/CN2020/079788 CN2020079788W WO2021184222A1 WO 2021184222 A1 WO2021184222 A1 WO 2021184222A1 CN 2020079788 W CN2020079788 W CN 2020079788W WO 2021184222 A1 WO2021184222 A1 WO 2021184222A1
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quantum dots
graphene quantum
conductive coating
raw materials
coating material
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French (fr)
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陈忠伟
余爱萍
毛治宇
熊俊威
黄明
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温州玖源锂电池科技发展有限公司
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • 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
    • 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

Definitions

  • the present invention relates to the technical field of lithium ion battery current collectors, in particular to a conductive coating material based on graphene quantum dots and derivatives thereof, and a high-rate start-stop lithium ion battery current collector coated with the material Applications.
  • the current collector plays an important role in communicating the external circuit and the internal electrochemical reaction, and is an indispensable part of the lithium ion battery. It can collect the current generated by the active material of the battery to form a larger current for external output.
  • copper foil and aluminum foil are the commonly used positive and negative current collectors for commercial lithium-ion batteries, respectively.
  • In the electrode preparation process it is necessary to mix the active material with conductive glue and the like to form a slurry to form a conductive coating, and then coat it on the current collector.
  • problems such as weak adhesion, poor conductivity, thick coating, and electrochemical corrosion of the current collector itself during the use of lithium-ion batteries often cause the current collector to not maximize its effect and seriously affect lithium.
  • the performance of ion batteries Therefore, looking for a conductive coating with high conductivity, high adhesion and thin layer is of great significance to the current collector technology of lithium-ion batteries and the improvement of the rate performance of lithium-ion batteries.
  • CN108091825A discloses a lithium-ion battery pole piece containing a porous current collector, a core-shell structured foamed microsphere capsule safety coating and an active material coating
  • CN107768676A discloses A current collector that removes the blank area reserved by the active material coating after intermittent coating or continuous coating and uses it for high energy density lithium ion batteries.
  • graphene quantum dot materials there have been some reports on graphene quantum dot materials.
  • CN102992311B discloses a method for preparing graphene quantum dots using carbon nanotubes as raw materials through simple and controllable water bath heating and stirring operations
  • WO2017000731A1 discloses a graphene oxide quantum dot Dots and a method for preparing composite nanomaterials composed of graphene and/or graphene-like structures
  • CN104386673B discloses a graphene quantum dot without adding any strong acid or base and a method for preparing the same.
  • the main difference between the above-mentioned prior art and the present invention is that the application is different.
  • the conductive adhesive layer prepared by using the material of the present invention is applied to the start-stop lithium-ion battery of a micro-hybrid car.
  • the battery can make the car wait for a red light, etc. ( When the engine is running at idling speed, the engine is turned off to save fuel, but it can be started quickly.
  • a conductive adhesive layer based on graphene quantum dots and derivatives thereof and the application of the material in high-rate start-stop lithium-ion batteries are expected.
  • the graphene quantum dots and their derivatives in this material are small in size and strong in conductivity.
  • the thickness of the conductive coating can be reduced, thereby significantly enhancing the adhesion between the electroactive substance and the current collector and improving
  • the electrode interface structure of the lithium ion battery reduces its impedance and improves the high rate performance of the battery, which can be well applied to start and stop lithium ion batteries.
  • the conductive adhesive layer can also inhibit the electrochemical corrosion of the aluminum foil current collector during the use of the lithium ion battery.
  • the technical problem to be solved by the present invention is to provide a conductive coating based on graphene quantum dots and derivatives thereof and the application of the coating in a high-rate start-stop lithium ion battery.
  • the conductive coating material containing graphene quantum dots and derivatives thereof has excellent high-rate performance in lithium ion batteries, simple steps, good reproducibility, and is suitable for industrial production.
  • a conductive coating material based on graphene quantum dots and derivatives thereof is proposed.
  • the raw materials of the conductive coating material include active materials, binders and dispersants.
  • the active materials account for 20% by weight of the total raw materials. -60%, the binder accounts for 1-15% of the total raw material weight, the dispersant accounts for 25-79% of the total raw material weight, and the active material is graphene quantum dots and their derivatives.
  • the aforementioned conductive coating material wherein the active material accounts for 20-48% by weight of the total raw materials, the binder accounts for 10-15% by weight of the total raw materials, and the dispersant accounts for 37-65% by weight of the total raw materials. %.
  • the aforementioned conductive coating material wherein the graphene quantum dots and derivatives thereof include one of graphene quantum dots, nitrogen-doped graphene quantum dots, boron-doped graphene quantum dots, and aminated graphene quantum dots. kind or more.
  • the aforementioned conductive coating material wherein the binder includes one or more of water-based LA-132, water-based hydroxymethyl cellulose, water-based styrene-butadiene emulsion, oil-based polyvinylidene fluoride, and polytetrafluoroethylene kind.
  • the aforementioned conductive coating material wherein the dispersant includes one or more of polyvinylpyrrolidone, cetyltrimethylammonium bromide, and cetyltrimethylammonium chloride.
  • the present invention has at least the following advantages:
  • the present invention prepares two-dimensional graphene and its derivative materials with high conductivity into zero-dimensional quantum dots to further reduce the particle size and increase the specific surface area, and then apply slurry preparation and other processes to the current collector To reduce the thickness of the conductive coating, increase the conductivity, and at the same time, it can significantly enhance the bonding effect of the electroactive material and the current collector, and is beneficial to the distribution of the active material on the conductive coating, improving the electrode interface structure of the lithium ion battery, and then Reduce its impedance and at the same time inhibit the electrochemical corrosion of the aluminum foil current collector during the use of the lithium ion battery.
  • the conductive coating material based on graphene quantum dots and its derivatives disclosed in the present invention has excellent electrical conductivity and high specific surface area, improves the electrode interface structure of lithium ion batteries, thereby reduces its impedance, and improves the high rate of the battery performance.
  • the present invention has simple steps, good reproducibility, and is suitable for industrialized production.
  • FIG. 1 is a low-magnification SEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention
  • FIG. 3 is a low-rate TEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention.
  • Example 5 is a SEM characterization diagram of graphene quantum dots in Example 2 according to the present invention.
  • Example 6 is a comparison diagram of EIS test results of lithium ion batteries obtained in Example 1, Comparative Example 1 and Comparative Example 2 according to the present invention
  • Fig. 7 shows the battery discharge curve performance of the lithium-ion battery obtained in Example 1 of the present invention at different rates
  • FIG. 8 shows the battery discharge curve performance at 30C of the lithium ion batteries obtained in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention.
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • PVDF polyvinylidene fluoride
  • dimethyl sulfoxide weigh 0.42 g of polyvinylidene fluoride (PVDF) and add 8 g of dimethyl sulfoxide, and mix them with a 2L phosphoric acid mixer to stir evenly. Then add 1.75g N-methylpyrrolidone dispersant and stir at high speed for 3h to make it evenly mixed. Then add 0.54 g of graphene quantum dots, stir at high speed for 5 hours and disperse to prepare conductive coating slurry. Among them, graphene quantum dots accounted for 48% of the total mass fraction of the slurry except water.
  • PVDF polyvinylidene fluoride
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • a high-precision coating machine is used to uniformly coat the above-mentioned conductive coating slurry on the current collector (a 10 ⁇ m thick aluminum foil is used for the positive electrode, and a 6 ⁇ m thick copper foil for the negative electrode), and then dried. And by adjusting the high-precision coating machine, the single-sided thickness of the conductive coating after drying is controlled to 500nm-1 ⁇ m. Then, the pre-treated aluminum foil and copper foil were coated with commercial ternary nickel-cobalt-manganese material (NMC523) cathode material and carbon anode material, and dried to prepare lithium-ion battery anode and cathode sheets. Finally, the lithium-ion battery is assembled by conventional button cell process, and the discharge capacity test and rate performance test at room temperature are performed.
  • NMC523 commercial ternary nickel-cobalt-manganese material
  • ternary nickel cobalt manganese material NMC523
  • commercial carbon anode graphite material conductive carbon black (a mixture of graphene, Ketjen black and Super-P mixed in a ratio of 1:0.5:0.5): carboxymethyl
  • CMC sodium cellulose
  • SBR styrene butadiene rubber compound
  • a 10 ⁇ m thick aluminum foil current collector is used for the positive electrode, and a 6 ⁇ m thick copper foil current collector is used for the negative electrode.
  • the two current collectors are coated with commercial ternary nickel cobalt manganese material (NMC523) positive electrode material and carbon negative electrode material.
  • NMC523 commercial ternary nickel cobalt manganese material
  • Table 1 shows the battery discharge capacity retention of lithium-ion batteries obtained in Example 1, Example 2, Example 3, Example 4, Example 5, Comparative Example 1 and Comparative Example 2 according to the present invention at different rates. Rate comparison. It can be seen from Table 1 that the conductive coating material based on graphene quantum dots and its derivatives of the present invention has higher performance at 5C, 10C, and 30C than conventional conductive coatings, which proves that the conductive coating is conductive The performance is better and the electron transfer rate is faster. The above results also indicate that the graphene quantum dots and their derivatives conductive coatings can be used in high-rate start-stop lithium-ion batteries.
  • FIG. 1 is a low-magnification SEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention
  • FIG. 2 is a high-magnification SEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention. It can be seen from Fig. 1 and Fig. 2 that the morphology of the nitrogen-doped graphene quantum dots of the present invention is spherical and the size is about 6 nm.
  • FIG. 3 is a low-rate TEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention
  • FIG. 4 is a high-rate TEM characterization diagram of nitrogen-doped graphene quantum dots according to Embodiment 1 of the present invention. It can be seen from FIG. 3 and FIG. 4 that the morphology of the nitrogen-doped graphene quantum dots of the present invention is spherical with a smaller size of 3-6 nm, which is more consistent with the morphology in FIG. 1 and FIG. 2.
  • FIG. 5 is a SEM characterization diagram of graphene quantum dots in Example 2 according to the present invention. It can be seen from FIG. 5 that the morphology of the graphene quantum dots of the present invention is spherical, the size is about 10 nm, and the size is relatively uniform.
  • Example 6 is a comparison diagram of EIS test results of lithium ion batteries obtained in Example 1, Comparative Example 1 and Comparative Example 2 according to the present invention. It can be seen from FIG. 6 that the battery impedances of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention are approximately 53 m ⁇ , 65 m ⁇ , and 88 m ⁇ , respectively. The results show that the battery impedance in Example 1 is significantly lower than that in Comparative Example 1 and Comparative Example 2, indicating that the graphene quantum dots and their derivatives in this material can significantly enhance the adhesion between the electroactive material and the current collector, and reduce it. impedance.
  • FIG. 7 shows the battery discharge curve performance of the lithium ion battery obtained in Example 1 according to the present invention at different rates. It can be seen from Figure 7 that the maximum discharge capacity of the battery at room temperature can reach 86% of the battery capacity at a rate of 30C, indicating that the battery can achieve high rate discharge. This is because the nitrogen-doped graphene quantum dots in the material are highly conductive and can reduce the thickness of the conductive coating after coating on the current collector, which can significantly improve the electrode interface structure of the lithium ion battery, thereby increasing the battery's high rate performance.
  • FIG. 8 shows the battery discharge curve performance at 30C of the lithium ion batteries obtained in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention. It can be seen from Figure 8 that the battery capacity can still maintain 85.9% when the cut-off voltage is 3.0V at 30C; while the comparative example 1 and comparative example 2 are at 30C, and the cut-off voltage is 3.0V. Maintained 54.3% and 36.3%, both of which were significantly lower than the results of Example 1.
  • the present invention provides based on the physical and chemical properties of graphene quantum dots and their derivatives to strengthen the adhesion between the conductive adhesive layer and the current collector, thereby improving the interface structure of lithium-ion batteries.
  • Graphene quantum dots and their derivatives are small in size and strong in conductivity.
  • the thickness of the conductive coating can be reduced, thereby significantly enhancing the adhesion between the electroactive material and the current collector, and can inhibit the aluminum foil current collector from Electrochemical corrosion during use of lithium ion batteries.
  • the conductive coating material has excellent electrical conductivity and high specific surface area, improves the electrode interface structure of the lithium ion battery, reduces its impedance, and improves the high rate performance of the battery.
  • the method has simple steps, good reproducibility, and is suitable for industrialized production.

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Abstract

本发明涉及一种基于石墨烯量子点及其衍生物的导电涂层材料，其原料包含活性材料、粘结剂和分散剂，以重量百分数计，所述活性材料占总原料重量的20-60％，所述粘结剂占总原料重量的1-15％，所述分散剂占总原料重量的25-79％，所述活性材料为石墨烯量子点及其衍生物。本发明的导电涂层材料应用于启停锂离子电池能够改善锂离子电池的电极界面结构，进而降低其阻抗，提高电池的高倍率性能。本发明步骤简单，重现性高，易于实现工业化生产。

Description

一种基于石墨烯量子点及其衍生物的导电涂层材料及其应用 技术领域
本发明涉及锂离子电池集流体技术领域，具体地，涉及一种基于石墨烯量子点及其衍生物的导电涂层材料及其在涂覆有该材料的高倍率启停锂离子电池集流体中的应用。
背景技术
集流体发挥着沟通外部电路与内部电化学反应的重要作用，是锂离子电池的不可或缺的组成部分。它能将电池活性物质产生的电流汇集起来以便形成较大的电流对外输出。目前，铜箔和铝箔分别是商业化锂离子电池常用的正极和负极集流体。在电极制备工艺中，需要将将活性物质与导电胶等混合制成浆料，形成导电涂层，然后涂覆于集流体上。但是在此过程中因存在粘结力弱、导电性差、涂层较厚以及集流体本身在锂离子电池使用过程中的电化学腐蚀等问题常常导致集流体不能最大化地发挥作用而严重影响锂离子电池的性能。因此，寻找高电导率、高粘结力且薄层的导电涂层对锂离子电池集流体工艺和提高锂离子电池倍率性能具有重要意义。
现有技术中关于石墨烯量子点及其衍生物的导电涂层材料用于电动汽车启停锂离子电池未见有公开报道。虽然锂离子电池集流体已有一些报道，例如，CN108091825A公开了一种含多孔集流体、核壳结构的发泡微球胶囊安全涂层和活性物质涂层的锂离子电池极片；CN107768676A公开了一种通过间歇涂布或连续涂布后清除活性物质涂层预留空白区域的集流体并将之用于高能量密度锂离子电池。同时关于石墨烯量子点材料已有一些报道，例如CN102992311B公开了一种以碳纳米管为原料通过简单可控的水浴加热搅拌操作制备石墨烯量子点的方法；WO2017000731A1公开了一种氧化石墨烯量子点及其与石墨烯和/或类石墨烯结构物构成的复合纳米材料的制备方法；CN104386673B公开了一种无需添加任何强酸强碱的石墨稀量子点及其制备方法。
上述的现有技术与本发明的主要区别在于：应用不同，利用本发明的材料制备出的导电胶层应用于微混动力汽车启停锂离子电池，该电池可使汽车在等待红灯等(发动机怠速运行)情况下熄火，节省燃油，但又能快速起动。
基于以上，期待一种基于石墨烯量子点及其衍生物的导电胶层以及该材料在高倍率启停锂离子电池中的应用。该材料中的石墨烯量子点及其衍生物尺寸较小，且导电性强，涂布于集流体上后能降低导电涂层厚度，从而显著增强电活性物质与集流体的粘结作用，改善锂离子电池的电极界面结构，进而降低其阻抗，提高电池的高倍率性能，能够很好的应用于启停锂离子电池。同时，该导电胶层亦能抑制铝箔集流体在锂离子电池使用过程中的电化学腐蚀。
发明内容
本发明要解决的技术问题在于提供一种基于石墨烯量子点及其衍生物的导电涂层以及该涂层在高倍率启停锂离子电池中的应用。所述的含石墨烯量子点及其衍生物的导电涂层材料在锂离子电池中具有优良的高倍率性能，步骤简单，重现性好，适合于工业化生产。
本发明的目的及解决其技术问题通过采用以下的技术方案来实现。依据本发明提出的一种基于石墨烯量子点及其衍生物的导电涂层材料，其原料包含活性材料、粘结剂和分散剂，以重量百分数计，所述活性材料占总原料重量的20-60％，所述粘结剂占总原料重量的1-15％，所述分散剂占总原料重量的25-79％，所述活性材料为石墨烯量子点及其衍生物。
前述的导电涂层材料，其中所述的活性材料占总原料重量的20-48％，所述粘结剂占总原料重量的10-15％，所述分散剂占总原料重量的37-65％。
前述的导电涂层材料，其中所述的石墨烯量子点及其衍生物包括石墨烯量子点、氮掺杂石墨烯量子点、硼掺杂石墨烯量子点、氨基化石墨烯量子点中的一种或多种。
前述的导电涂层材料，其中所述的粘结剂包括水系LA-132、水系羟甲基纤维素、水系丁苯乳液、油系聚偏氟乙烯、聚四氟乙稀中的一种或多种。
前述的导电涂层材料，其中所述的分散剂包括聚乙烯吡咯烷酮、溴化十六烷基三甲铵、氯化十六烷基三甲铵中的一种或多种。
本发明的目的及解决其技术问题通过采用以下的技术方案来实现。依据本发明提出的导电涂层材料在启停锂离子电池中的应用。
借由上述技术方案，本发明(名称)至少具有下列优点：
(1)本发明通过将具有高导电性的二维石墨烯及其衍生物材料制备成零维量子点以进一步降低颗粒尺寸，增大比表面积，再通过浆料制备等工艺涂布于集流体上，降低导电涂层厚度，提高电导率，同时能显著增强电活性物质与集流体的粘结作用，且有利于活性物质在导电涂层上的分布，改善锂离子电池的电极界面结构，进而降低其阻抗，同时能抑制铝箔集流体在锂离子电池使用过程中的电化学腐蚀。
(2)本发明公开的基于石墨烯量子点及其衍生物的导电涂层材料具有优良的电导率和高比表面积，改善锂离子电池的电极界面结构，进而降低其阻抗，提高电池的高倍率性能。
(3)本发明步骤简单，重现性好，适合于工业化生产。
附图说明
图1为根据本发明实施例1中的氮掺杂石墨烯量子点的低倍率SEM表征图；
图2为根据本发明实施例1中的氮掺杂石墨烯量子点的高倍率SEM表征图；
图3为根据本发明实施例1中的氮掺杂石墨烯量子点的低倍率TEM表征图；
图4为根据本发明实施例1中的氮掺杂石墨烯量子点的高倍率TEM表征图；
图5为根据本发明实施例2中的石墨烯量子点的SEM表征图；
图6为根据本发明实施例1、对比实施例1和对比实施例2中得到的锂离子电池的EIS测试结果对比图；
图7为根据本发明实施例1中得到的锂离子电池在不同倍率下 的电池放电曲线性能；
图8为根据本发明实施例1、对比实施例1和对比实施例2中得到的锂离子电池在30C时的电池放电曲线性能。
具体实施方式
下面结合附图和实施例对本发明作进一步的阐述，应理解，这些实施例仅用于说明本发明而不用于限制本发明的范围。此外应理解，在阅读了本发明讲授的内容之后本领域技术人员可以对本发明做各种改动或修改，这些等价同样落于本申请所附权利要求书所限定的范围。
实施例1
分别称取0.12g羟甲基纤维素(CMC)、0.30g丁苯乳液(SBR)并加入8g水，混合后采用磷酸2L混料机搅拌均匀。然后加入1.75g溴化十六烷基三甲铵分散剂，高速搅拌3h使其混合均匀。再加入2g氮掺杂石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中氮掺杂石墨烯量子点占除水外的总浆料质量分数的48％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
实施例2
分别称取0.12g羟甲基纤维素(CMC)、0.30g丁苯乳液(SBR)并加入8g水，混合后采用磷酸2L混料机搅拌均匀。然后加入1.75g溴化十六烷基三甲铵分散剂，高速搅拌3h使其混合均匀。再加入2g石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中石墨烯量子点占除水外的总浆料质量分数的48％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。 并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
实施例3
分别称取0.12g羟甲基纤维素(CMC)、0.30g丁苯乳液(SBR)并加入8g水，混合后采用磷酸2L混料机搅拌均匀。然后加入1.75g溴化十六烷基三甲铵分散剂，高速搅拌3h使其混合均匀。再加入1g石墨烯量子点、1g氨基化石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中石墨烯量子点占除水外的总浆料质量分数的48％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
实施例4
分别称取0.12g羟甲基纤维素(CMC)、0.30g丁苯乳液(SBR)并加入8g水，混合后采用磷酸2L混料机搅拌均匀。然后加入1.75g溴化十六烷基三甲铵分散剂，高速搅拌3h使其混合均匀。再加入0.54g石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中石墨烯量子点占除水外的总浆料质量分数的20％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
实施例5
分别称取0.42g聚偏氟乙烯(PVDF)并加入8g二甲基亚砜，混合后采用磷酸2L混料机搅拌均匀。然后加入1.75g N-甲基吡咯烷酮分散剂，高速搅拌3h使其混合均匀。再加入0.54g石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中石墨烯量子点占除水外的总浆料质量分数的48％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
实施例6
分别称取0.12g羟甲基纤维素(CMC)、0.30g丁苯乳液(SBR)并加入8g水，混合后采用磷酸2L混料机搅拌均匀。然后加入1g溴化十六烷基三甲铵分散剂和0.75g聚乙烯吡咯烷酮(PVP)，高速搅拌3h使其混合均匀。再加入2g氮掺杂石墨烯量子点，高速搅拌5h分散后制得导电涂层浆料。其中氮掺杂石墨烯量子点占除水外的总浆料质量分数的48％。
采用高精密涂布机将上述导电涂层浆料均匀地涂敷在集流体上(正极采用10μm厚的铝箔，负极采用6μm厚的铜箔)，然后烘干。并通过调节高精密涂布机控制导电涂层烘干后的单面厚度500nm-1μm。然后分别在已经过预处理的铝箔和铜箔上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
对比实施例1
按商业化三元镍钴锰材料(NMC523)或商业化碳负极石墨材料：导电碳黑(石墨烯、科琴黑及Super-P以1:0.5:0.5的比例混合的混合物)：羧甲基纤维素钠(CMC)和丁苯橡胶复合物(SBR)＝8:1:1的质量 比例混合均匀，然后涂覆在集流体上，经真空干燥、切片后，得到三元正/负极。烘干后分别制得锂离子电池的正负极片。最后进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
对比实施例2
正极采用10μm厚的铝箔集流体，负极采用6μm厚的铜箔集流体，在两个集流体上涂敷商业化三元镍钴锰材料(NMC523)正极材料和碳负极材料，烘干后分别制得锂离子电池的正负极片。进行常规扣式电池工艺组装得到锂离子电池，并进行常温下放电容量测试和倍率性能测试。
表1 根据本发明实施例1-5、对比实施例1与对比实施例2中得到的锂离子电池在不同倍率下的电池放电容量保有率比较
Figure PCTCN2020079788-appb-000001
表1为根据本发明实施例1、实施例2、实施例3、实施例4、实施例5、对比实施例1与对比实施例2中得到的锂离子电池在不同倍率下的电池放电容量保有率比较。从表1可以看出，本发明的基于石墨烯量子点及其衍生物导电涂层材料与常规导电涂层相比，在5C，10C，30C倍率下性能均更高，证明该导电涂层导电性更好，电子传输速率更快。上述结果同时表明该石墨烯量子点及其衍生物导电涂层可用于高倍率启停锂离子电池中。
附图说明：
图1为根据本发明实施例1中的氮掺杂石墨烯量子点的低倍率SEM表征图；图2为根据本发明实施例1中的氮掺杂石墨烯量子点的高倍率SEM表征图。从图1和图2中可以看出，本发明的氮掺杂 石墨烯量子点的形貌为球状，尺寸大约为6nm。
图3为根据本发明实施例1中的氮掺杂石墨烯量子点的低倍率TEM表征图；图4为根据本发明实施例1中的氮掺杂石墨烯量子点的高倍率TEM表征图。从图3和图4中可以看出，本发明的氮掺杂石墨烯量子点的形貌为球状，尺寸较小，为3-6nm，与图1和图2中形态较一致。
图5为根据本发明实施例2中的石墨烯量子点的SEM表征图。从图5中可以看出，本发明的石墨烯量子点的形貌为球状，尺寸大约为10nm，且尺寸较均一。
图6为根据本发明实施例1、对比实施例1和对比实施例2中得到的锂离子电池的EIS测试结果对比图。从图6中可以看出，本发明实施例1、对比实施例1和对比实施例2对应的电池阻抗约分别为53mΩ、65mΩ和88mΩ。该结果表明实施例1中电池阻抗明显小于对比实施例1和对比实施例2，表明该材料中的石墨烯量子点及其衍生物能显著增强电活性物质与集流体的粘结作用，降低其阻抗。
图7为根据本发明实施例1中得到的锂离子电池在不同倍率下的电池放电曲线性能。从图7中可以看出，电池在常温下最大放电容量在30C倍率下放电可以达到电池容量的86％，表明该电池可实现大倍率放电。这是由于该材料中的氮掺杂石墨烯量子点导电性强，且涂布于集流体上后能降低导电涂层厚度，可显著改善锂离子电池的电极界面结构，进而提高电池的高倍率性能。
图8为根据本发明实施例1、对比实施例1和对比实施例2中得到的锂离子电池在30C时的电池放电曲线性能。从图8中可以看出，电池在30C下，截止电压为3.0V时容量仍可保持85.9％；而对比实施例1和对比实施例2在30C时，截止电压为3.0V时容量仅分别可保持54.3％和36.3％，均显著低于实施例1的结果。
综上所述，本发明提供的基于石墨烯量子点及其衍生物的本身的物理化学性质以强化导电胶层与集流体之间的粘结力，进而改善锂离子电池的界面结构，所用的石墨烯量子点及其衍生物尺寸较小，导电性强，涂布于集流体上后能降低导电涂层厚度，从而显著增强电活性物质与集流体的粘结作用，能抑制铝箔集流体在锂离子电池 使用过程中的电化学腐蚀。该导电涂层材料具有优良的电导率和高比表面积，改善锂离子电池的电极界面结构，进而降低其阻抗，提高电池的高倍率性能。本发明步骤简单，重现性好，适合于工业化生产。
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明披露的技术范围内，可轻易想到的变化或替换，都应该涵盖在本发明的保护范围之内。因此，本发明的保护范围应该以权利要求书的保护范围为准。

Claims (6)

  1. 一种基于石墨烯量子点及其衍生物的导电涂层材料，其原料包含活性材料、粘结剂和分散剂，以重量百分数计，所述活性材料占总原料重量的20-60％，所述粘结剂占总原料重量的1-15％，所述分散剂占总原料重量的25-79％，所述活性材料为石墨烯量子点及其衍生物。
  2. 根据权利要求1所述的导电涂层材料，其中所述的活性材料占总原料重量的20-48％，所述粘结剂占总原料重量的10-15％，所述分散剂占总原料重量的37-65％。
  3. 根据权利要求1所述的导电涂层材料，其中所述的石墨烯量子点及其衍生物包括石墨烯量子点、氮掺杂石墨烯量子点、硼掺杂石墨烯量子点、氨基化石墨烯量子点中的一种或多种。
  4. 根据权利要求1所述的导电涂层材料，其中所述的粘结剂包括水系LA-132、水系羟甲基纤维素、水系丁苯乳液、油系聚偏氟乙烯、聚四氟乙稀中的一种或多种。
  5. 根据权利要求1所述的导电涂层材料，其中所述的分散剂包括聚乙烯吡咯烷酮、溴化十六烷基三甲铵、氯化十六烷基三甲铵中的一种或多种。
  6. 根据权利要求1-5任一项所述的导电涂层材料在启停锂离子电池中的应用。
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