Preparation method of composite carbon material, composite carbon material prepared by the method and application thereof

Abstract

The application discloses a preparation method of a composite carbon material, the composite carbon material prepared by the method and application of the composite carbon material. A mixed binder containing an organic binder, a metal element, an additive and a solvent is mixed with an activated carbon material, and then dried to obtain the composite carbon material. According to the principle of similarity and compatibility, the organic ligand can form a sufficient mixture with the binder, and the pi bond can make the metal element sufficiently combined with the binder, thereby improving the adhesion. The presence of the binder can make a modified carbon material containing a hydrophobic layer. The hydrophobic layer can help to hinder the contact between active sites of the carbon material and hydrogen ions, thereby improving the hydrogen evolution overpotential of the carbon material. In addition, the metal element can form crystallization sites of metal lead, the charging and discharging process of a lead-acid battery is a conversion process between the metal lead and lead sulfate, more crystallization sites of the metal lead can refine the grain size of the charged product metal lead, and can indirectly refine the grain size of the discharged product lead sulfate, thereby prolonging the cycle life of the lead-carbon battery.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a composite carbon material, the composite carbon material prepared by the method and application thereof, and belongs to the field of conductive materials. BACKGROUND

[0002] Lead-acid batteries are widely used in various fields due to their high stability, low production cost and high safety, but the performance of lead-acid batteries is required to be higher in hybrid electric vehicles or renewable energy power plants, and the lead-acid batteries are usually required to work in a partial state of charge, which can cause a large amount of irreversible lead sulfate to accumulate on the negative electrode of the battery during the cycle, resulting in sulfation of the battery and failure. Without solving this problem, lead-carbon batteries are developed, and a certain amount of carbon material is added to the negative electrode of the lead-acid battery to enhance the conductivity of the negative electrode, so as to alleviate the sulfation of the battery. However, the addition of carbon material brings the problem of hydrogen evolution of the battery, and how to further solve the sulfation problem of the battery and improve the hydrogen evolution overpotential of the carbon material is the research focus in the scientific research field. SUMMARY

[0003] The application provides a preparation method of a lead-carbon battery negative electrode, which comprises the following steps: fully mixing carbon powder, boron and / or lead and / or strontium powder, an organic ligand and an organic binder, according to the principle of similarity and compatibility, the organic ligand can form a sufficient mixture with the binder, and the pi bond in the organic ligand enables the boron and / or lead and / or strontium powder to be fully combined with the binder, so that the adhesion of the organic binder is improved. The presence of the binder can make the modified carbon material contain a hydrophobic layer. The hydrophobic layer helps to hinder the contact between the active sites of the carbon material and hydrogen ions, and improves the hydrogen evolution overpotential of the carbon material. In addition, the boron and / or lead and / or strontium powder can form crystallization sites of metallic lead, the charging and discharging process of the lead-acid battery is a conversion process between metallic lead and lead sulfate, more crystallization sites of metallic lead can refine the grain size of the charging product metallic lead, and the purpose of indirectly refining the grain size of the discharging product lead sulfate can be achieved, so that the cycle life of the lead-carbon battery is prolonged.

[0004] According to one aspect of the application, a preparation method of a composite carbon material is provided, comprising the following steps:

[0005] Mixing a mixed binder containing an organic binder, a metal element, an additive and a solvent with an activated carbon material, drying to obtain the composite carbon material.

[0006] The organic binder is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR);

[0007] The metal element is selected from at least one of boron, lead and strontium;

[0008] The additive is selected from at least one of benzothiazole, oxazole;

[0009] The solvent is selected from at least one of N-methyl pyrrolidone (NMP), ethanol, acetone, methanol, ethyl acetate, chloroform, benzene, xylene, methyl sulfide, ethyl sulfide, thiophene.

[0010] The mass ratio of the organic binder to the metal element is 0.01-50 g: 0.01-10 g;

[0011] The mass ratio of the organic binder to the additive is 0.01-50 g: 0.01-10 g;

[0012] The ratio of the amount of the organic binder to the solvent is 0.01-50 g: 2-200 ml.

[0013] The viscosity of the mixed binder ranges from (4000-8000) mPa·S.

[0014] The specific surface area of the activated carbon material is 300-3000 m 2 / g;

[0015] The mass ratio of the organic binder to the activated carbon material is 0.01-50 g: 1-1000 g.

[0016] The mixing is ball milling.

[0017] The drying temperature is 40-150℃;

[0018] The drying time is 1-48 h.

[0019] According to another aspect of the present application, a composite carbon material prepared by the above preparation method is provided.

[0020] According to another aspect of the present application, an electrode containing the above composite carbon material is provided.

[0021] According to another aspect of the present application, a lead-acid battery containing the above electrode is provided.

[0022] The beneficial effects that can be produced by the present application include:

[0023] The carbon powder, boron and or lead and or strontium powder, organic ligand and organic binder are mixed well, according to the principle of similar compatibility, the organic ligand can form a mixture with the binder, and the π bond in the organic ligand makes the boron and or lead and or strontium powder combine with the binder, which improves the adhesion of the organic binder. The presence of the binder can make the modified carbon material contain a hydrophobic layer. The hydrophobic layer helps to hinder the contact between the active sites of the carbon material and hydrogen ions, thereby improving the hydrogen evolution overpotential of the carbon material. In addition, the boron and or lead and or strontium powder can form crystallization sites of metallic lead, and the charging and discharging process of the lead-acid battery is a conversion process between metallic lead and lead sulfate. More metallic lead crystallization sites can refine the grain size of the charged product metallic lead, which can indirectly refine the grain size of the discharged product lead sulfate, thereby prolonging the cycle life of the lead-carbon battery. DETAILED DESCRIPTION

[0024] The application will be described in detail below with reference to the examples.

[0025] Unless otherwise specified, the raw materials in the examples are commercially purchased and used directly without treatment; the instruments and equipment used are used according to the recommended parameters of the manufacturers.

[0026] In the examples, the cycle life of the lead-carbon battery is tested by using the Blue Power charging and discharging instrument and the Xinwei charging and discharging tester.

[0027] In the examples, the adhesion of the binder after adding the organic ligand is tested by using a rotational viscometer.

[0028] Example 1

[0029] Step one: the composite carbon material is prepared by the following method:

[0030] First, 2 g of polyvinylidene fluoride (PVDF), 0.5 g of boron, and 0.5 g of benzothiazole are dissolved in 20 ml of N-methyl pyrrolidone (NMP), and the viscosity of the mixture is tested to be 4500 mPa·S. Then, 10 g of activated carbon material with a specific surface area of 1000 m 2 / g is added to the solution to form a mixture, and then the mixture is ball milled and dried at 80°C for 24 hours.

[0031] Step two: the lead-carbon battery electrode and the lead-carbon battery are prepared by the following method, and the cycle stability and gas evolution amount are tested:

[0032] 1) Preparation of negative electrode: (1) 600 g of lead powder, 9 g of the prepared carbon material, 8.4 g of barium sulfate, and 0.3 g of polypropylene short fibers with a length of 5 mm and a diameter of 0.5-1.5 μm were premixed with a high-speed mixer, and 84 g of deionized water was added to the premixed powder while stirring, and the stirring was continued for 10 min to obtain a lead paste; (2) the lead paste was coated onto a metal lead grid with a size of 70 mm in length, 50 mm in width, and 2 mm in thickness, and the grid was cured and dried to obtain a lead-carbon battery negative electrode. The curing temperature was 40 °C, the humidity was 80%, and the curing time was 20 hours; the drying temperature was 80 °C, and the time was 24 hours;

[0033] 2) Preparation of positive electrode: the positive electrode of the lead-acid battery was prepared according to the same process steps as steps (1) and (2) for the preparation of the negative electrode, except that no carbon material was added to the positive electrode;

[0034] 3) Preparation of lead-carbon battery: three positive electrode plates and two negative electrode plates were placed in parallel in sequence with an interval, and a PE separator for gel lead-carbon batteries was placed between the positive and negative electrode plates. The two negative electrode plates were connected in parallel and welded, and the three positive electrode plates were connected in parallel and welded. The total mass of the positive electrode active material (the total mass of the lead paste after drying on the three positive electrode plates) was 60.0 g, the total mass of the positive electrode active material refers to the total mass of the lead paste contained in the three parallel-welded positive electrode plates, and the total mass of the negative electrode active material (the total mass of the lead paste after drying on the two negative electrode plates) was 52.9 g, the total mass of the negative electrode active material refers to the total mass of the lead paste contained in the two parallel-welded negative electrode plates. The positive and negative electrode grids were conventional lead grids with a size of 70 mm in length, 50 mm in width, and 2 mm in thickness. The positive and negative electrodes were placed in a tightly assembled battery box, the battery box had a length of 76 mm, a width of 40 mm, and a height of 100 mm, and 83 g of sulfuric acid electrolyte with a mass concentration of 1.275 g / ml prepared above was injected into the battery box;

[0035] The battery was subjected to normal temperature life test, and the test conditions were as follows: at 25 °C, 4.2 A constant current discharge for 59 seconds, 18 A discharge for 1 second, 6.3 A current and 2.3 V voltage constant current and constant voltage charging for 60 seconds, the charging and discharging conditions were cycled 3600 times, then the battery was left to stand for 40 hours, and the cycle was restarted after 40 hours. The termination condition of the life test was that the voltage of the battery decreased to below 1.2 V; the assembled internal mixing type battery could run 52265 cycles in the normal temperature life test. Compared with the test results of the ordinary lead-acid battery with the same lead content under the same test conditions (7200 cycles), the normal temperature cycle life of the assembled lead-carbon battery could reach 7.3 times the life of the traditional lead-acid battery.

[0036] The battery is subjected to normal temperature gas emission amount test, the test method is as follows: the battery is fully sealed with commercial paraffin wax, then a gas guide pipe is inserted at the exhaust port of the battery, the end of the gas guide pipe in the battery passes through the length of 5mm of the rubber plug, the end of the gas guide pipe outside the working electrode chamber is introduced into the device for testing the volume of gas by drainage method, the inner and outer surfaces of the rubber plug through which the gas guide pipe passes and various connections between the gas guide pipe and the commercial drainage method gas volume measuring device are sealed firmly with commercial AB glue, the purpose is to ensure that the gas generated from the battery end is completely introduced into the commercial drainage method gas volume measuring device, the device is used to collect the gas volume generated from the battery end, and the gas generation rate is calculated, in the test process, the battery system is placed in a constant temperature environment of 25 DEG C, a constant voltage of 2.4V is applied to the battery for 48 hours, and the gas generation rate of the lead-carbon battery of the formula carbon material is 0.15ml / (wh·h) through calculation.

[0037] Example 2

[0038] According to the requirements of example 1, without changing other conditions, the amount of polyvinylidene fluoride (PVDF) added in step one is changed to 0.1g, the viscosity of the prepared binder is 4000mPa·S, and the assembled internal mixing type battery can run for 30983 cycles in normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal mixing lead-carbon battery can reach 4.3 times of the life of the traditional lead-acid battery. The gas generation rate of the assembled lead-carbon battery in a room temperature environment is 0.23ml / (wh·h).

[0039] Example 3

[0040] According to the requirements of example 1, without changing other conditions, the amount of polyvinylidene fluoride (PVDF) added in step one is changed to 20g, the viscosity of the prepared binder is 5000mPa·S, and the assembled internal mixing type battery can run for 49709 cycles in normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal mixing lead-carbon battery can reach 6.9 times of the life of the traditional lead-acid battery. The gas generation rate of the assembled lead-carbon battery in a room temperature environment is 0.17ml / (wh·h).

[0041] Example 4

[0042] According to the requirements of example 1, without changing other conditions, the activated carbon in step one is replaced with activated carbon with a specific surface area of 500m 2The assembled internal-mixing lead-carbon battery can run 39362 cycles in the normal temperature life test. Compared with the test results of the common lead-acid battery with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal-mixing lead-carbon battery can reach 5.5 times the life of the conventional lead-acid battery. The gas production rate of the assembled lead-carbon battery in the room temperature environment is 0.25 ml / (wh·h).

[0043] Example 5

[0044] According to the requirements of Example 1, without changing other conditions, the activated carbon in step one is replaced with activated carbon with a specific surface area of 2500 m 2 The assembled internal-mixing lead-carbon battery can run 39362 cycles in the normal temperature life test. Compared with the test results of the common lead-acid battery with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal-mixing lead-carbon battery can reach 5.5 times the life of the conventional lead-acid battery. The gas production rate of the assembled lead-carbon battery in the room temperature environment is 0.25 ml / (wh·h).

[0045] Example 6

[0046] According to the requirements of Example 1, without changing other conditions, the amount of boron added in step one is changed to 0.1 g, and the assembled internal-mixing lead-carbon battery can run 49376 cycles in the normal temperature life test. Compared with the test results of the common lead-acid battery with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal-mixing lead-carbon battery can reach 6.9 times the life of the conventional lead-acid battery. The gas production rate of the assembled lead-carbon battery in the room temperature environment is 0.18 ml / (wh·h).

[0047] Example 7

[0048] According to the requirements of Example 1, without changing other conditions, the amount of boron added in step one is changed to 10 g, and the assembled internal-mixing lead-carbon battery can run 51985 cycles in the normal temperature life test. Compared with the test results of the common lead-acid battery with the same lead element content under the same test conditions (7200 cycles), the normal temperature cycle life of the internal-mixing lead-carbon battery can reach 7.2 times the life of the conventional lead-acid battery. The gas production rate of the assembled lead-carbon battery in the room temperature environment is 0.14 ml / (wh·h).

[0049] Example 8

[0050] According to the requirements of Example 1, without changing other conditions, the elemental boron in step one is replaced by the same mass of elemental lead, and the assembled internal mixing type battery can run 49874 cycles in the room temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the room temperature cycle life of the internal mixing lead-carbon battery can reach 6.9 times the life of the traditional lead-acid battery. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.20 ml / (wh·h).

[0051] Example 9

[0052] According to the requirements of Example 1, without changing other conditions, the elemental boron in step one is replaced by the same mass of elemental lead, and the assembled internal mixing type battery can run 49874 cycles in the room temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the room temperature cycle life of the internal mixing lead-carbon battery can reach 6.9 times the life of the traditional lead-acid battery. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.20 ml / (wh·h).

[0053] Example 10

[0054] According to the requirements of Example 1, without changing other conditions, the elemental boron in step one is replaced by the same mass of elemental lead, and the assembled internal mixing type battery can run 49874 cycles in the room temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the room temperature cycle life of the internal mixing lead-carbon battery can reach 6.9 times the life of the traditional lead-acid battery. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.20 ml / (wh·h).

[0055] Example 11

[0056] According to the requirements of Example 1, without changing other conditions, the elemental boron in step one is replaced by the same mass of elemental lead, and the assembled internal mixing type battery can run 49874 cycles in the room temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead element content under the same test conditions (7200 cycles), the room temperature cycle life of the internal mixing lead-carbon battery can reach 6.9 times the life of the traditional lead-acid battery. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.20 ml / (wh·h).

[0057] Example 11

[0058] According to the requirements of Example 1, without changing other conditions, the addition amount of benzothiazole in step one is changed to 10 g. The viscosity of the prepared binder is 7500 mPa·S, and the assembled internal mixing type battery can run 57921 cycles in the room temperature life test. Compared with the test results of the ordinary lead-acid battery with the same lead element content under the same test conditions (7200 cycles), the room temperature cycle life of the internal mixing lead-carbon battery can reach 8.0 times the life of the traditional lead-acid battery. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.18 ml / (wh·h).

[0059] Comparative Example 1

[0060] Lead-acid battery: According to the requirements of Example 1, without changing other conditions, the step two “1) Preparation of negative electrode: (1) 600 g of lead powder, 9 g of prepared carbon material, 8.4 g of barium sulfate, and 0.3 g of polypropylene short fiber with a length of 5 mm and a diameter of 0.5-1.5 μm are pre-mixed with a high-speed mixer. While stirring, 84 g of deionized water is added to the pre-mixed powder, and stirring is continued for 10 min to obtain lead paste;” is changed to (without adding any carbon material) “1) Preparation of negative electrode: (1) 600 g of lead powder, 8.4 g of barium sulfate, and 0.3 g of polypropylene short fiber with a length of 5 mm and a diameter of 0.5-1.5 μm are pre-mixed with a high-speed mixer. While stirring, 84 g of deionized water is added to the pre-mixed powder, and stirring is continued for 10 min to obtain lead paste;” other steps remain unchanged, and the preparation of the lead-acid battery is carried out. The assembled internal mixing type battery can run 7200 cycles in the room temperature life test. The lead-acid battery has no hydrogen evolution problem, so the gas production rate test is not performed.

[0061] Comparative Example 2

[0062] Lead-carbon battery: According to the requirements of Example 1, without changing other conditions, without preparing composite carbon material, directly using activated carbon with a specific surface area of 1300 m 2 / g as the carbon material additive for lead-carbon battery, the assembled internal mixing type battery can run 10800 cycles in the room temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.40 ml / (wh·h).

[0063] Comparative Example 3

[0064] According to the requirements of Example 1, without changing other conditions, the addition amount of polyvinylidene fluoride (PVDF) in step one is changed to 0.01 g. The viscosity of the prepared binder is 5500 mPa·S, and the prepared carbon material cannot form an effective hydrophobic layer and cannot improve the hydrogen evolution overpotential of the carbon material, resulting in that the assembled internal mixing type battery can run 7200 cycles in the room temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.41 ml / (wh·h).

[0065] Comparative Example 4

[0066] According to the requirements of Example 1, without changing other conditions, the amount of boron added in step one was changed to 0 g. The viscosity of the prepared binder was 4500 mPa·S. The prepared carbon material formed a hydrophobic layer, but could not effectively improve the crystallization state of lead and lead sulfate. The internal resistance of the carbon material was too large, resulting in that the assembled internal mixing type battery could only run for 3600 cycles in the normal temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment was 0.09 ml / (wh·h).

[0067] Comparative Example 5

[0068] According to the requirements of Example 1, without changing other conditions, the boron added in step one was replaced with an equal amount of iron. The viscosity of the prepared binder was 4000 mPa·S. The iron could not be fully combined with the organic binder, and could not form effective lead crystallization sites, resulting in that the assembled internal mixing type battery could only run for 7200 cycles in the normal temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment was 0.91 ml / (wh·h).

[0069] Comparative Example 6

[0070] According to the requirements of Example 1, without changing other conditions, the carbon material added in step one was replaced with an equal amount of carbon material with a specific surface area of 10 m 2 / g. Since the specific surface area of the carbon material was too low, it could not provide more lead crystallization sites, and could not play a role in refining lead sulfate grains, resulting in that the assembled internal mixing type battery could only run for 10800 cycles in the normal temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment was 0.85 ml / (wh·h).

[0071] Comparative Example 7

[0072] According to the requirements of Example 1, without changing other conditions, the benzothiazole added in step one was replaced with an equal amount of oleylamine. The viscosity of the prepared binder was 3000 mPa·S. The oleylamine could not form effective complexes with boron, lead, or strontium, could not enhance the connection strength of these elements with the carbon material and the bonding strength with the organic binder, could not form a large number of lead crystallization sites, and could not play a role in refining lead sulfate grains, resulting in that the assembled internal mixing type battery could only run for 7200 cycles in the normal temperature life test. The gas production rate of the assembled lead-carbon battery in a room temperature environment was 0.91 ml / (wh·h).

[0073] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the technical solutions of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1.A method for preparing a composite carbon material, comprising the following steps: mixing a mixed binder containing an organic binder, a metal element, an additive and a solvent with an activated carbon material, and drying to obtain the composite carbon material. The organic binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose and butadiene-styrene rubber. The metal element is selected from at least one of boron, lead and strontium. The additive is selected from at least one of benzothiazole and oxazole. The solvent is selected from at least one of N-methylpyrrolidone, ethanol, acetone, methanol, ethyl acetate, chloroform, benzene, xylene, methyl sulfide, ethyl sulfide and thiophene. The mass ratio of the organic binder to the metal element is 0.01-50 g:0.01-10 g. The mass ratio of the organic binder to the additive is 0.01-50 g:0.01-10 g. The ratio of the amount of the organic binder to the solvent is 0.01-50 g:2-200 ml. The mass ratio of the organic binder to the activated carbon material is 0.01-50 g:1-1000 g. The composite carbon material is applied to a lead-acid battery electrode material. The activated carbon material has a specific surface area of 300-3000 m 2 / g; 2.The method according to claim 1, wherein the mixing is ball milling. 3.The method according to claim 1, wherein the drying is performed at a temperature of 40-150 ℃ for 1-48 h. 4.A composite carbon material prepared by the method of any one of claims 1-3. 5.An electrode, comprising the composite carbon material of claim 4. 6.A lead-acid battery, comprising the electrode of claim 5. ​ ​ ​ ​ ​ ​ ​