Preparation method of positive electrode material of high-specific-energy low-temperature-resistant carbon-niobium-based hybrid capacitor

Abstract

The invention discloses a preparation method of a positive electrode material of a high-specific-energy low-temperature-resistant carbon-niobium-based hybrid capacitor, and belongs to the technical field of electrochemical energy storage. The method comprises the following steps: pre-carbonizing a biomass material or a coal precursor material to obtain carbon powder; mixing carbon powder with salt, and activating in an atmosphere furnace to obtain a porous graphite carbon material; and repeatedly washing the porous graphite carbon material with a pickling solution to remove impurities, washing the porous graphite carbon material with deionized water until the solution is neutral, and then drying the porous graphite carbon material to obtain the positive electrode material. The porous carbon with a graphitized structure is prepared through high-temperature pre-carbonization and activation treatment of the carbon precursor material, so that the ion and electron conductivity is greatly improved, and the rate capability and cycle stability of the positive electrode material are enhanced. The negative electrode is made of a niobium-based material, and by virtue of an intercalation pseudocapacitance energy storage mechanism, the negative electrode shows multiplying power, cycle life and low-temperature performance superior to those of a traditional battery type negative electrode.

Description

Technical Field

[0001] The invention relates to a method for preparing a positive electrode material of a high-specific-energy, low-temperature-resistant carbon-niobium-based hybrid capacitor, belonging to the technical field of electrochemical energy storage. Background Art

[0002] As a new type of energy storage device that combines the high power density and fast charge and discharge capabilities of supercapacitors with the high energy density of lithium-ion batteries, hybrid capacitors have gradually become a research hotspot. Through their unique working principles and structural design, hybrid capacitors have achieved a dual increase in energy density and power density while maintaining long cycle life and fast response capabilities, providing innovative ideas for solving the limitations of traditional energy storage technologies.

[0003] In particular, the introduction of high-specific-energy and low-temperature-resistant carbon-niobium-based hybrid capacitor energy storage technology has further promoted the development of hybrid capacitor technology. This technology not only inherits the basic advantages of hybrid capacitors, but also significantly improves the working performance of energy storage systems in low-temperature environments by adopting carbon-niobium-based composite electrode materials, broadening its application range. In addition, while meeting the requirements of rapid response and high safety, this technology also has long life and stable output performance, providing a reliable solution for efficient energy storage in harsh environments.

[0004] As the global demand for clean and renewable energy continues to grow, the research and development of this technology has become a hot area. In particular, in applications with strong demand for efficient energy storage, such as electric vehicles, aerospace, and low-temperature industrial equipment, high-specific-energy and low-temperature-resistant carbon-niobium-based hybrid capacitor energy storage technology has shown broad prospects. For example, in the field of electric vehicles, energy storage systems have higher requirements for energy density and charging and discharging efficiency, and this technology can not only extend the endurance of electric vehicles in extremely cold environments, but also significantly shorten the charging time, which will help promote the further development of the new energy vehicle market.

[0005] However, the technology still faces some key challenges in practical applications. First, the preparation cost of carbon-niobium-based composite electrode materials is high, which limits their large-scale production and commercial application. Secondly, the long-term maintenance of electrochemical stability and low-temperature performance still needs to be further optimized. Finally, the capacity attenuation problem after long-term use is also one of the key factors restricting the widespread application of this technology, which needs to be solved through innovations in materials and structural design to ensure the reliability and stability of the energy storage system.

[0006] Therefore, the present invention proposes a new type of high specific energy and low temperature resistant carbon-niobium based hybrid capacitor energy storage technology to solve the problems of low energy density, poor cycle stability, high production cost and poor low temperature performance of traditional capacitors, and promote their wider application in the field of modern energy storage. Summary of the invention

[0007] In order to solve the problems existing in the background technology, the present invention provides a method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance.

[0008] To achieve the above object, the present invention adopts the following technical solution: a method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance, the method comprising the following steps:

[0009] S1: Pre-carbonization: pre-carbonizing the biomass material or coal precursor material at a temperature below 700°C, with a pre-carbonization rate of 0.1°C / min-20°C / min and a pre-carbonization time of 1 hour to obtain carbon powder;

[0010] S2: Activation: Mix the carbon powder and salt in a mass ratio of 1:2-4, and heat them to the target activation temperature in a lower atmosphere furnace under an inert atmosphere. After a certain period of constant temperature, cool them to room temperature in a cooling chamber to obtain a porous graphite carbon material;

[0011] S3: The obtained porous graphite carbon material is repeatedly washed with an acid wash solution to remove impurities, then washed with deionized water until the solution is neutral, and then dried to obtain a positive electrode material.

[0012] The inert atmosphere is high-purity nitrogen or high-purity argon, and the volume flow rate is 50 mL / min-500 mL / min.

[0013] The heating rate of the atmosphere furnace is 0.1°C / min-20°C / min.

[0014] The concentration of the pickling solution is 0.01 mol / L-10 mol / L.

[0015] The water washing method is to achieve solid-liquid separation through vacuum filtration or through a centrifuge.

[0016] The drying method is vacuum drying, hot air drying or natural evaporation.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention obtains porous carbon with a graphitized structure by high-temperature pre-carbonization and activation of carbon precursor materials, which greatly improves the ionic and electronic conductivity and enhances the rate performance and cycle stability of the positive electrode material. The negative electrode adopts niobium-based materials, and by virtue of the intercalation pseudocapacitor energy storage mechanism, it exhibits superior rate, cycle life and low-temperature performance to traditional battery-type negative electrodes. The construction of carbon-niobium-based hybrid capacitors not only achieves high energy density, but also broadens the operating temperature range and prolongs the service life. Compared with other hybrid capacitor systems, it shows obvious advantages and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a TEM image of the coal-based porous graphene prepared in Example 1;

[0020] Figure 2 is the UV Raman image of the coal-based porous graphene prepared in Example 1;

[0021] Figure 3 is the X-ray diffraction pattern of the coal-based porous graphene prepared in Example 1;

[0022] Figure 4 is a nitrogen adsorption isotherm diagram of the coal-based porous graphene prepared in Example 1;

[0023] Figure 5 It is the Regone diagram of energy density and power density representing the corresponding performance of the hybrid capacitors prepared in Assembly Example 1 and Example 2;

[0024] Figure 6 It is a schematic diagram of the structure of a high specific energy and low temperature resistant carbon-niobium based hybrid capacitor. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] A method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance, the method comprising the following steps:

[0027] S1: Pre-carbonization: pre-carbonizing the biomass material or coal precursor material at a temperature below 700°C, with a pre-carbonization rate of 0.1°C / min-20°C / min and a pre-carbonization time of 1 hour to obtain carbon powder;

[0028] S2: Activation: Mix the carbon powder and salt in a mass ratio of 1:2-4, wherein the salt is potassium hydroxide or potassium carbonate, and heat to a target activation temperature (600°C to 1000°C) in a lower atmosphere furnace under an inert atmosphere, keep the temperature constant for a certain period of time (0.5h-10h), and then cool to room temperature in a cooling chamber to obtain a porous graphite carbon material;

[0029] S3: The obtained porous graphite carbon material is repeatedly washed with an acid wash solution (HF or dilute hydrochloric acid or dilute nitric acid or dilute acetic acid) to remove impurities, then washed with deionized water until the solution is neutral, and then dried to obtain a positive electrode material.

[0030] The inert atmosphere is high-purity nitrogen or high-purity argon, and the volume flow rate is 50 mL / min-500 mL / min.

[0031] The heating rate of the atmosphere furnace is 0.1°C / min-20°C / min.

[0032] The concentration of the pickling solution is 0.01 mol / L-10 mol / L.

[0033] The water washing method is to achieve solid-liquid separation through vacuum filtration or through a centrifuge.

[0034] The drying method is vacuum drying, hot air drying or natural evaporation.

[0035] The positive electrode material obtained after drying is stirred and mixed evenly with the conductive agent acetylene black, the binder sodium carboxymethyl cellulose and styrene-butadiene rubber in a ratio of 90:5:3:2, and then coated on both sides of the carbon-coated aluminum foil, and then cut into pole pieces after vacuum drying.

[0036] The negative electrode plate is prepared according to the following steps: the niobium-based material, the conductive agent acetylene black, and the binder polyvinylidene fluoride are stirred and mixed in a ratio of 90:5:5, and then coated on both sides of the copper foil, and then vacuum dried and cut into plates.

[0037] A high specific energy and low temperature resistant carbon-niobium based hybrid capacitor of the present invention comprises a diaphragm 1, a positive current collector 2, a negative current collector 3, a positive electrode sheet 4, a negative electrode sheet 5, a shell and an electrolyte; the shell is provided with a diaphragm 1, a positive current collector 2, a negative current collector 3, a positive electrode sheet 4, a negative electrode sheet 5 and an electrolyte, the tail end of the diaphragm 1 is arranged in a surrounding manner inside the shell, and the head end of the diaphragm 1 is arranged in a circuitous manner in the space surrounding the tail end of the diaphragm 1, and the number of circuitous layers can be set according to the capacity requirements of the hybrid capacitor. A positive electrode sheet 4 is fixed to one side of the head end of the diaphragm 1, and a negative electrode sheet 5 is fixed to the other side of the head end of the diaphragm 1. After the diaphragm 1 is circuitous, two adjacent positive electrode sheets 4 share a positive current collector 2, and two adjacent negative electrode sheets 5 share a negative current collector 3. Both the positive and negative current collectors are connected with pole ears, and can be connected to an external circuit through a wire.

[0038] The positive electrode current collector 2 is carbon-coated aluminum foil.

[0039] The negative electrode current collector 3 is copper foil.

[0040] The material of the positive electrode plate 4 is a carbon material, such as activated carbon, template carbon, graphene or biomass carbon.

[0041] The material of the negative electrode plate 5 is a niobium-based material, such as TiNb2O7, TiNbO4 or Ti2Nb 10 O 29 .

[0042] The electrolyte is an organic solution of lithium hexafluorophosphate, ethylene carbonate, diethyl carbonate and dimethyl carbonate, wherein the volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate is 1:1:1. The concentration of the electrolyte is 0.5-5 mol / L;

[0043] The diaphragm 1 is a glass fiber diaphragm.

[0044] The adhesive of the pole piece is polyvinylidene fluoride or polytetrafluoroethylene or sodium carboxymethyl cellulose.

[0045] The conductive agent of the electrode is conductive carbon black or acetylene black or carbon nanotubes.

[0046] The positive electrode material obtained after drying is stirred and mixed evenly with the conductive agent acetylene black, the binder sodium carboxymethyl cellulose and styrene-butadiene rubber in a ratio of 90:5:3:2, and then coated on both sides of the carbon-coated aluminum foil, and then cut into pole pieces after vacuum drying.

[0047] The negative electrode plate is prepared according to the following steps: the niobium-based material, the conductive agent acetylene black, and the binder polyvinylidene fluoride are stirred and mixed in a ratio of 90:5:5, and then coated on both sides of the copper foil, and then vacuum dried and cut into plates.

[0048] Embodiment 1:

[0049] S1: Xinjiang Zhundong coal is used as the carbon precursor, and Zhundong coal powder is heated at 700℃ for 5℃min -1 Pre-carbonize at a rate of 1 h to obtain carbon powder;

[0050] S2: Carbon powder and KOH with a mass ratio of 1:4 were directly mixed and heated at 5 °C min under nitrogen atmosphere. -1 The mixture was heated to the target activation temperature at a rate of 1000 rpm and then cooled naturally to room temperature.

[0051] S3: The obtained carbon material was treated with 5 mol L -1 The mixture was repeatedly washed with 10 wt.% HCl and 10 wt.% HF to remove impurities, and then washed with deionized water until the solution was neutral.

[0052] Embodiment 2:

[0053] Dissolve 5 mmol of isopropyl titanate and 2.5 mmol of niobium pentachloride in 60 mL of anhydrous ethanol and stir for 50 min. Then, transfer the solution to a 100 mL reactor and heat at 180 ° C for 8 h. After cooling to room temperature, collect the product by centrifugation, transfer it to a vacuum oven, and dry it at 65 ° C for 10 h to obtain the TiNb2O7 precursor.

[0054] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0055] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance, characterized in that: The method comprises the following steps: S1: Pre-carbonization: pre-carbonizing the biomass material or coal precursor material at a temperature below 700°C, with a pre-carbonization rate of 0.1°C / min-20°C / min and a pre-carbonization time of 1 hour to obtain carbon powder; S2: Activation: Mix the carbon powder and salt in a mass ratio of 1:2-4, and heat them to the target activation temperature in a lower atmosphere furnace under an inert atmosphere. After a certain period of constant temperature, cool them to room temperature in a cooling chamber to obtain a porous graphite carbon material; S3: The obtained porous graphite carbon material is repeatedly washed with an acid wash solution to remove impurities, then washed with deionized water until the solution is neutral, and then dried to obtain a positive electrode material.

2. The method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance according to claim 1, characterized in that: The inert atmosphere is high-purity nitrogen or high-purity argon, and the volume flow rate is 50 mL / min-500 mL / min.

3. The method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance according to claim 1, characterized in that: The heating rate of the atmosphere furnace is 0.1°C / min-20°C / min.

4. The method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance according to claim 1, characterized in that: The concentration of the pickling solution is 0.01 mol / L-10 mol / L.

5. The method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance according to claim 1, characterized in that: The water washing method is to achieve solid-liquid separation through vacuum filtration or through a centrifuge.

6. The method for preparing a positive electrode material of a carbon-niobium based hybrid capacitor with high specific energy and low temperature resistance according to claim 1, characterized in that: The drying method is vacuum drying, hot air drying or natural evaporation.

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