Graphene-based lead storage battery negative electrode lead paste as well as preparation method and application thereof

Abstract

The invention discloses graphene-based lead storage battery negative electrode lead paste as well as a preparation method and application thereof, and belongs to the technical field of lead-acid storage batteries. The negative electrode lead paste comprises the following components in parts by weight: 90-110 parts of lead powder; 6 to 8 parts of a graphene / carbon nanotube coated PTFE composite emulsion; 12 to 18 parts of deionized water; and 7-12 parts of sulfuric acid. The preparation method comprises the following steps that S1, lead powder and sulfuric acid are mixed and then stirred for a reaction, and acidified lead powder is obtained; and S2, adding the graphene / carbon nanotube coated PTFE composite emulsion into the acidified lead powder, carrying out vacuum shearing and stirring, adding deionized water, and uniformly mixing to obtain the graphene-based lead storage battery negative electrode lead paste. By adding the graphene / carbon nanotube (at) PTFE composite emulsion into the negative electrode lead paste, the dispersity of the composite carbon material in the lead paste can be effectively improved, so that a continuous network structure is formed, and the conductivity of a negative electrode active material is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lead-acid batteries, and particularly relates to a graphene-based lead paste for the negative electrode of a lead battery, a preparation method thereof, and an application thereof. Background Art

[0002] With the growth of human environmental protection awareness and the demand for clean and renewable energy, lead batteries have changed from low-current and low-power applications to high-current and high-power applications, which requires lead batteries to have higher specific energy and longer service life. However, the negative electrode of existing lead batteries is prone to sulfation, resulting in a decrease in the porosity of the electrode plate, a decrease in conductivity, and a decrease in charge and discharge capacity.

[0003] Related research shows that when carbon materials are added to the negative active material of lead-acid batteries, the sulfation rate of the negative electrode plate of the battery can be significantly reduced, and the service life of the lead battery can be extended. The key to extending its service life is to improve the dispersion of carbon materials in the negative electrode plate of the battery. As a single-atom layer graphite structure, graphene has good flexibility, and its specific surface area is greater than 2600 m 2 / g, which enables graphene to form face-to-face contact with the active material of the electrode. Related research shows that when graphene is added to the electrode material of the battery, the conductivity of the electrode can be greatly improved.

[0004] In the traditional paste-making process, carbon materials, lead powder, water, and sulfuric acid are mainly simply mechanically mixed. For example, patent document CN113764627A provides a lead-carbon battery negative electrode lead paste formula and a preparation method thereof. In this document's formula, graphene as a carbon material is added in powder form. Due to its light weight, it is extremely easy to float on the surface of the aqueous solution and cannot be evenly dispersed. Therefore, at present, graphene is mostly added in the form of an aqueous solution of graphene. However, its density still differs little from that of pure water, and due to the small particle size of graphene, its aqueous solution is milky and has no granular feeling. Therefore, on the premise of ensuring the amount of graphene used, under the dual action of pure water and the aqueous solution of graphene, the apparent specific gravity of the lead paste is often low, and it is difficult to ensure that the final lead paste meets the requirements for filling and coating, which directly affects the porosity of the electrode plate and ultimately affects the service life and performance of the storage battery.

[0005] Therefore, a new technical means is urgently needed to solve the above technical problems. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a graphene-based lead paste for the negative electrode of a lead battery to solve the problem in the background art that the carbon material in the lead paste of the negative electrode of the lead battery is unevenly dispersed, resulting in poor battery performance;

[0007] Another purpose of the present invention is to provide a preparation method of a graphene-based lead paste for the negative electrode of a lead battery to prepare the negative electrode lead paste;

[0008] A third object of the present invention is to provide an application of the above-mentioned graphene-based lead-acid battery negative electrode lead paste in a lead-acid battery.

[0009] The object of the present invention can be achieved by the following technical solutions:

[0010] In a first aspect, the present invention provides a graphene-based lead-acid battery negative electrode lead paste, which comprises the following components in parts by weight:

[0011] 90-110 parts of lead powder;

[0012] 6-8 parts of graphene / carbon nanotube@PTFE (polytetrafluoroethylene) composite emulsion;

[0013] 12-18 parts of deionized water;

[0014] 7-12 parts of sulfuric acid.

[0015] As a further aspect of the present invention, the preparation method of the graphene / carbon nanotube@PTFE composite emulsion comprises the following steps:

[0016] Step 1: Place graphene in an acid solution, perform ultrasonic treatment, and collect the acidified hydrophilic graphene; disperse the hydrophilic graphene in deionized water, and then add carbon nanotubes, and perform ultrasonic dispersion to obtain a graphene / carbon nanotube dispersion;

[0017] Step 2: After freeze-drying the graphene / carbon nanotube dispersion, perform vacuum calcination to obtain a graphene / carbon nanotube composite carbon material;

[0018] Step 3: Add the graphene / carbon nanotube composite carbon material to the PTFE emulsion, perform ultrasonic treatment and reaction to uniformly coat the PTFE on the surface of the graphene / carbon nanotube composite carbon material to obtain a graphene / carbon nanotube@PTFE composite emulsion.

[0019] As a further aspect of the present invention, the acid solution in Step 1 is a sulfuric acid solution with a mass concentration of 40%-50%.

[0020] As a further aspect of the present invention, in Step 1, the dosage (mass) ratio of graphene to carbon nanotubes is 1-3:1.

[0021] As a further aspect of the present invention, in Step 1, the solid content of the graphene / carbon nanotube dispersion is 6%-12%.

[0022] As a further aspect of the present invention, in Step 2, the vacuum calcination temperature is 600-800°C, and the calcination time is 1-2 h.

[0023] As a further solution of the present invention, in the step 3, the dosage (mass) ratio of the graphene / carbon nanotube composite carbon material to PTFE is 5:0.2 - 0.8.

[0024] As a further solution of the present invention, in the step 3, the solid content of the PTFE emulsion is 60%.

[0025] As a further solution of the present invention, the power of the ultrasonic treatment is 300 - 500 W.

[0026] As a further solution of the present invention, the concentration of the sulfuric acid is 1.2 - 1.3 g / mL and is used for acidifying the lead powder.

[0027] As a further solution of the present invention, the purity of the lead powder is ≥99.9% and the particle size is 1 - 5 μm.

[0028] In the second aspect, the present invention provides a method for preparing a graphene-based lead-acid battery negative electrode lead paste, comprising the following steps:

[0029] S1. Mix the lead powder with sulfuric acid and carry out a stirring reaction to generate a PbSO3 / PbO2 passivation layer, obtaining acidified lead powder;

[0030] S2. Add the graphene / carbon nanotube@PTFE composite emulsion to the acidified lead powder, carry out vacuum shearing and stirring, then add deionized water to adjust the viscosity, and mix evenly to obtain the graphene-based lead-acid battery negative electrode lead paste.

[0031] As a further solution of the present invention, in S2, the rotation speed of the vacuum shearing and stirring is 1500 - 2500 rpm, and the time of the vacuum shearing and stirring is 20 - 40 min.

[0032] As a further solution of the present invention, in S1, the stirring speed is 200 - 400 rpm, and the stirring time is 20 - 40 min.

[0033] In the third aspect, the present invention provides an application of the graphene-based lead-acid battery negative electrode lead paste in a lead-acid battery.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. By adding the graphene / carbon nanotube@PTFE composite emulsion to the negative electrode lead paste, the present invention can effectively improve the dispersion of the composite carbon material in the lead paste, form a continuous network structure, and further improve the conductivity of the negative electrode active material.

[0036] 2. In the present invention, the surface of graphene contains a large number of oxygen-containing groups such as hydroxyl and carboxyl groups. These groups will be further oxidized in an acidic environment to form more carboxyl and hydroxyl groups. These additional functional groups increase the hydrophilicity of the graphene surface, making it easier to disperse in water. Ultrasonic waves destroy the agglomerated structure of graphene and carbon nanotubes through mechanical vibration and cavitation effect, so that they are uniformly dispersed in the solution. Control the time and frequency of ultrasonic dispersion to avoid the decline of material performance caused by excessive dispersion. Mix the acidified graphene and carbon nanotubes in a certain proportion, add deionized water and continue ultrasonic dispersion. The addition of carbon nanotubes further enhances the dispersion effect of graphene and improves the mechanical properties and electrical conductivity of the composite material through the synergistic effect between the two. Using freeze-drying, the composite carbon material is directly transformed from a solid state to a gaseous state, thus retaining the three-dimensional network structure of graphene and carbon nanotubes, removing the moisture in the dispersion liquid while reducing the density of the material. Under vacuum conditions, the freeze-dried sample is calcined at high temperature, which can remove the residual organic substances (such as acidifying agents and dispersants) and make the interface between graphene and carbon nanotubes more firm. During the calcination process, some carbon nanotubes may be graphitized, further improving the electrical conductivity and mechanical properties of the composite material. PTFE emulsion is a polymer material with excellent lubricity and corrosion resistance. Through ultrasonic treatment, the particles in the PTFE emulsion can form a uniform coating layer on the surface of the composite carbon material. This process mainly relies on the cavitation effect and mechanical stirring action generated by ultrasonic waves. The coating of PTFE not only improves the lubrication performance of the composite material, but also enhances its stability in high-temperature and corrosive environments. In addition, the addition of PTFE may further improve the mechanical properties and electrical conductivity of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below with reference to the accompanying drawings.

[0038] Figure 1 It is a schematic diagram of the preparation process flow of the graphene / carbon nanotube@PTFE composite emulsion of the present invention. SPECIFIC EMBODIMENTS

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] Obviously, the following description is only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing, or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0041] However, there will be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter recited in the claims.

[0042] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0043] Preparation Example 1

[0044] Please refer to Figure 1 , a preparation method of a graphene / carbon nanotube@PTFE composite emulsion, comprising the following steps:

[0045] Step 1: Place 10 g of graphene in a sulfuric acid solution with a mass concentration of 45%, ultrasonically treat it at a power of 400 W for 40 min, filter and collect to obtain acidified hydrophilic graphene; disperse the hydrophilic graphene in deionized water, then add 5 g of carbon nanotubes, and ultrasonically disperse to obtain a graphene / carbon nanotube dispersion with a solid content of 8%;

[0046] Step 2: After freeze-drying the graphene / carbon nanotube dispersion, calcine it in vacuum at 700 °C for 2 h to obtain a graphene / carbon nanotube composite carbon material;

[0047] Step 3: Weigh the graphene / carbon nanotube composite carbon material and PTFE according to a mass ratio of 5:0.5. Add the graphene / carbon nanotube composite carbon material to a PTFE emulsion with a solid content of 60%, and ultrasonically treat and react at a power of 400 W for 30 min to uniformly coat PTFE on the surface of the graphene / carbon nanotube composite carbon material to obtain a graphene / carbon nanotube@PTFE composite emulsion.

[0048] Preparation Example 2

[0049] A preparation method of graphene / carbon nanotube@PTFE composite emulsion, which is different from Preparation Example 1 in that in Step 1, the solid content of the graphene / carbon nanotube dispersion is 6%, and the other components and steps remain the same.

[0050] Preparation Example 3

[0051] A preparation method of graphene / carbon nanotube@PTFE composite emulsion, which is different from Preparation Example 1 in that in Step 1, the solid content of the graphene / carbon nanotube dispersion is 12%, and the other components and steps remain the same.

[0052] Example 1

[0053] A graphene-based lead-acid battery negative electrode lead paste, by weight, includes the following components:

[0054] 100 parts of lead powder

[0055] 7 parts of graphene / carbon nanotube@PTFE composite emulsion (prepared by Preparation Example 1)

[0056] 15 parts of deionized water

[0057] 10 parts of sulfuric acid;

[0058] The preparation method of the negative electrode lead paste includes the following steps:

[0059] S1. Weigh according to the above weight parts. After mixing lead powder and sulfuric acid, stir and react at a speed of 300 rpm for 30 min to generate a PbSO3 / PbO2 passivation layer, and obtain acidified lead powder;

[0060] S2. Add graphene / carbon nanotube@PTFE composite emulsion to the acidified lead powder, perform high-speed vacuum shearing and stirring at a speed of 2000 rpm for 30 min, then add deionized water to adjust the viscosity, and mix evenly to obtain the graphene-based lead-acid battery negative electrode lead paste.

[0061] Example 2

[0062] A graphene-based lead-acid battery negative electrode lead paste, which is different from Example 1 in that the graphene / carbon nanotube@PTFE composite emulsion is prepared by Preparation Example 2, and the other components remain the same;

[0063] The preparation method of the negative electrode lead paste is the same as that of Example 1.

[0064] Example 3

[0065] A graphene-based lead-acid battery negative electrode lead paste, which is different from Example 1 in that the graphene / carbon nanotube@PTFE composite emulsion is prepared by Preparation Example 3, and the other components remain the same;

[0066] The preparation method of the negative electrode lead paste is the same as that in Example 1.

[0067] Example 4

[0068] A graphene-based lead-acid battery negative electrode lead paste, by weight, comprises the following components:

[0069] 92 parts of lead powder

[0070] 6 parts of graphene / carbon nanotube@PTFE composite emulsion (prepared in Preparation Example 1)

[0071] 12 parts of deionized water

[0072] 7 parts of sulfuric acid;

[0073] The preparation method of the negative electrode lead paste is the same as that in Example 1.

[0074] Example 5

[0075] A graphene-based lead-acid battery negative electrode lead paste, by weight, comprises the following components:

[0076] 118 parts of lead powder

[0077] 8 parts of graphene / carbon nanotube@PTFE composite emulsion (prepared in Preparation Example 1)

[0078] 18 parts of deionized water

[0079] 12 parts of sulfuric acid;

[0080] The preparation method of the negative electrode lead paste is the same as that in Example 1.

[0081] Comparative Preparation Example 1

[0082] A preparation method of a graphene / carbon nanotube composite material, comprising the following steps:

[0083] Step 1: Place 10 g of graphene in a sulfuric acid solution with a mass concentration of 45%, ultrasonically treat it at a power of 400 W for 40 min to obtain acidified hydrophilic graphene; disperse the hydrophilic graphene in deionized water, then add 5 g of carbon nanotubes, and ultrasonically disperse to obtain a graphene / carbon nanotube dispersion with a solid content of 8%;

[0084] Step 2: After freeze-drying the graphene / carbon nanotube dispersion, calcine it in vacuum at 700 °C for 2 h to obtain a graphene / carbon nanotube composite carbon material;

[0085] Comparative Preparation Example 2

[0086] A preparation method of a graphene-carbon nanotube@PTFE composite emulsion, comprising the following steps:

[0087] Step 1: Place 10 g of graphene in a sulfuric acid solution with a mass concentration of 45%, and ultrasonically treat it at a power of 400 W for 40 min to obtain acidified hydrophilic graphene; disperse the hydrophilic graphene in deionized water, then add 5 g of carbon nanotubes, and ultrasonically disperse to obtain a graphene-carbon nanotube dispersion with a solid content of 8%.

[0088] Step 2: After drying the graphene-carbon nanotube dispersion, a graphene-carbon nanotube composite carbon material is obtained.

[0089] Step 3: Weigh the graphene-carbon nanotube composite carbon material and PTFE according to a mass ratio of 5:0.5. Add the graphene-carbon nanotube composite carbon material to a PTFE emulsion with a solid content of 60%, and ultrasonically treat and react at a power of 400 W for 30 min to obtain a graphene-carbon nanotube@PTFE composite emulsion.

[0090] Comparative Preparation Example 3

[0091] A preparation method of a graphene / carbon nanotube / PTFE composite emulsion, which is different from Preparation Example 1 in that in Step 3, stirring treatment is adopted, and the rest of the steps and parameters remain the same. Step 3 is specifically as follows: Weigh the graphene / carbon nanotube composite carbon material and PTFE according to a mass ratio of 5:0.5. Add the graphene / carbon nanotube composite carbon material to a PTFE emulsion with a solid content of 60%, and ultrasonically treat and react at a power of 400 W for 30 min to obtain a graphene / carbon nanotube / PTFE composite emulsion.

[0092] Comparative Example 1

[0093] A graphene-based lead-acid battery negative electrode lead paste, which is different from Example 1 in that the graphene / carbon nanotube@PTFE composite emulsion prepared in Preparation Example 1 is replaced with the graphene / carbon nanotube composite material prepared in Comparative Preparation Example 1, and the rest of the components remain the same;

[0094] The preparation method of the negative electrode lead paste is the same as that of Example 1.

[0095] Comparative Example 2

[0096] A graphene-based lead-acid battery negative electrode lead paste, which is different from Example 1 in that the graphene / carbon nanotube@PTFE composite emulsion prepared in Preparation Example 1 is replaced with the graphene-carbon nanotube@PTFE composite emulsion prepared in Comparative Preparation Example 2, and the rest of the components remain the same;

[0097] The preparation method of the negative electrode lead paste is the same as that of Example 1.

[0098] Comparative Example 3

[0099] A graphene-based negative electrode lead paste for lead-acid batteries, which is different from that in Example 1 in that the graphene / carbon nanotube@PTFE composite emulsion prepared in Preparation Example 1 is replaced with the graphene / carbon nanotube / PTFE composite emulsion prepared in Comparative Preparation Example 3, and the other components remain the same;

[0100] The preparation method of the negative electrode lead paste is the same as that in Example 1.

[0101] The negative electrode lead pastes of the lead-acid batteries prepared in Examples 1-5 and Comparative Examples 1-3 were prepared into negative electrode plates of lead-acid batteries through processes of smearing, curing, and drying, assembled into experimental batteries of the 6-DZF-20 model, and tested for normal temperature capacity, cycle life, and low-temperature high-current discharge with reference to the national standard GB / T22199-2017 of the battery. The test results are shown in Table 1.

[0102] Table 1

[0103] Normal temperature capacity / min Cycle life / times Low temperature high current discharge / min Example 1 151.4 483 114 Example 2 144.8 469 106 Example 3 148.5 474 109 Example 4 146.1 471 107 Example 5 149.6 476 110 Comparative example 1 115.8 388 78 Comparative example 2 128.2 402 92 Comparative example 3 134.7 423 99

[0104] As can be seen from Table 1, the graphene / carbon nanotube@PTFE composite emulsion can effectively enhance the reversibility of the reaction of the negative electrode plate More high-energy lead participates in the redox reaction, which is beneficial to the construction of the conductive network of the lead-acid battery electrode and the stability of the electrode, thereby increasing its normal temperature capacity; using PTFE to uniformly coat the surface of the composite carbon material can effectively inhibit the hydrogen evolution reaction, further improving the rate performance and cycle stability; through ultrasonic dispersion assistance, the dispersion stability of graphene and carbon nanotubes is improved, and the conductivity of the material is increased.

[0105] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0106] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A graphene-based lead-acid battery negative electrode lead paste, characterized in that: According to parts by weight, it includes the following components: Lead powder 90-110 parts; 6-8 parts of graphene / carbon nanotube@PTFE composite emulsion; 12-18 parts of deionized water; 7-12 parts of sulfuric acid.

2. The graphene-based lead-acid battery negative electrode lead paste according to claim 1, characterized in that: The preparation method of the graphene / carbon nanotube@PTFE composite emulsion comprises the following steps: Step 1, placing graphene in an acid solution, ultrasonically treating, and collecting the acidified hydrophilic graphene; dispersing the hydrophilic graphene in deionized water, adding carbon nanotubes, and ultrasonically dispersing to obtain a graphene / carbon nanotube dispersion; Step 2, freeze-drying the graphene / carbon nanotube dispersion, and then vacuum calcining to obtain a graphene / carbon nanotube composite carbon material; Step 3: adding the graphene / carbon nanotube composite carbon material into the PTFE emulsion, and subjecting the mixture to ultrasonic treatment to react, thereby obtaining the graphene / carbon nanotube@PTFE composite emulsion.

3. A graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: The acid solution in step 1 is a sulfuric acid solution with a mass concentration of 40%-50%.

4. The graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: In the step 1, the usage ratio of graphene to carbon nanotubes is 1-3:

1.

5. The graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: In the step 1, the solid content of the graphene / carbon nanotube dispersion is 6%-12%.

6. The graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: In the step 2, the vacuum calcination temperature is 600-800° C., and the calcination time is 1-2 hours.

7. The graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: In the step 3, the usage ratio of the graphene / carbon nanotube composite carbon material and PTFE is 5:0.2-0.

8.

8. The graphene-based lead-acid battery negative electrode lead paste according to claim 2, characterized in that: The power of the ultrasonic treatment is 300-500W.

9. A method for preparing a graphene-based lead-acid battery negative electrode lead paste as claimed in claim 1, characterized in that: The following steps are involved: S1. The lead powder is mixed with sulfuric acid and stirred to react to obtain an acidified lead powder; S2. Add graphene / carbon nanotube@PTFE composite emulsion to the acidified lead powder, and after vacuum shear stirring, add deionized water and mix evenly to obtain graphene-based lead paste for negative electrode of lead-acid battery.

10. Use of the graphene-based lead paste for negative electrode of lead-acid battery as claimed in claim 1 in lead-acid battery.

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