Positive lead paste, preparation method thereof and storage battery

Abstract

The invention belongs to the technical field of lead-acid battery production, and discloses a positive electrode lead paste and a preparation method thereof, and a storage battery, the positive electrode lead paste at least comprises, by mass, 80-90% of lead powder, 5-10% of sulfuric acid, 3-9% of pure water, 0.2-1% of tetrabasic lead sulfate, 0.1-0.5% of polyaniline, and 0.3-0.8% of polytetrafluoroethylene. Furthermore, a certain supporting effect is provided for the cured lead paste, the structural strength of the lead paste is further improved, the compactness degree in the lead paste can be improved to a certain extent through filling of polyaniline, and then the compactness degree of an oxide layer between the lead paste and the grid is synchronously improved, so that the binding force between the lead paste and the grid is improved, and the service life of the lead paste is prolonged. The lead paste is prevented from falling off.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of cosmetic production, and in particular to a positive lead paste, a preparation method thereof and a storage battery. BACKGROUND

[0002] Since its birth, the lead storage battery has developed to now and occupies an important position in the energy market and is widely used in the civil market and various industries, such as communication, power stations, emergency lights, vehicles and the like. One of the main reasons is that the lead-acid storage battery is currently a renewable product that can be recycled in the energy industry. After decades of efforts and improvements, the lead-acid battery has relatively small pollution to the human living environment, and has superiority in recycling compared with other batteries. Therefore, in a comprehensive comparison, the lead-acid storage battery can be called a "green battery". However, the valve-regulated lead-acid storage battery has many problems, such as active material falling off and initial capacity loss. Regardless of the cause, the poor cycle performance of the battery restricts the pace of development of the lead-acid storage battery.

[0003] There is a relatively important factor affecting the cycle performance of the battery, that is, the binding force between the active material and the grid. When the binding force between the two is poor, the active material falls off from the grid, thereby affecting the cycle performance of the battery.

[0004] On the other hand, the binding force between the active material and the grid is improved through the formation of a corrosion layer therebetween. When the corrosion layer is too thin, the binding force between the active material and the grid is poor, thereby causing the active material to fall off.

[0005] However, if the corrosion layer is too thick, on the one hand, the grid is severely corroded, causing the grid to be prone to breakage. On the other hand, the formation of the thick corrosion layer causes too much material to be loaded on the grid, and the strength of the loaded material itself can decrease, and the more loaded material also brings greater load to the grid, accelerating the wear of the grid.

[0006] To this end, Chinese Patent Application No. 201810554053.6 discloses a curing and drying process for positive plates of lead-acid batteries, including curing and drying of positive plates and negative plates: placing the positive plates coated with lead paste in a curing room with a temperature of 40-50 DEG C and a humidity of 98-100% for 4-6 hours; increasing the temperature to 80-90 DEG C, maintaining the humidity at 98-100%, and introducing oxygen-rich air to maintain the pressure of the curing box at 0.4-0.6 MPa, and curing for 4-6 hours; introducing oxygen-rich air and drying for 6-10 hours.

[0007] The scheme optimizes the curing process parameters such as temperature, humidity and curing time, shortens the time consumption of the curing process, and to some extent, improves the service life of the battery.

[0008] Chinese patent application 201810448538.7 discloses a positive electrode lead paste for lead-acid batteries and a preparation method thereof. The positive electrode lead paste is composed of the following substances: 180-220 g of graphite, 80-90 g of polyester fiber, 10-12 kg of sulfuric acid solution, and 8-10 kg of pure water, based on 100 kg of lead powder. The positive electrode lead paste of this scheme does not add sulfate and metal oxide, which is conducive to the transformation of the lead paste from 3BS to 4BS type during the curing stage, and improves the ratio between the two types of crystal α-PbO2 and β-PbO2 of PbO2 after formation.

[0009] Thus, the positive plate lead paste active material macrostructure has a clear skeleton appearance, and the 4BS macrostructure of the lead paste is retained during the formation process and converted into the macrostructure of the PbO2 active material. The positive plate active material with a skeleton structure softens and falls off relatively slowly, and has a longer cycle life.

[0010] As can be seen, the above prior art improves the cycle life of the battery from aspects such as curing process of the positive plate and optimization of the lead paste formula. In addition, Chinese patent application 202310386340.1 discloses a lead-calcium-tin-copper-silver-sodium-rare earth grid alloy, positive plate grid and lead-acid battery, which optimizes the composition of the grid alloy to improve the corrosion resistance of the grid, thereby improving the service life of the battery.

[0011] The problem to be solved by the present scheme is: how to provide a lead paste formula different from the prior art to improve the adhesion between the lead paste and the grid. SUMMARY

[0012] The purpose of the present application is to provide a new lead paste formula, which adds tetrabasic lead sulfate to the composition of the lead paste, which can increase α-PbO2 with a porous skeleton mixed structure in the positive material, thereby improving the structural strength of the active material itself, reducing the shedding of the active material, and more importantly, by adding polyaniline and polytetrafluoroethylene, further providing certain support effect to the cured lead paste, further improving the structural strength of the lead paste. The filling of polyaniline can improve the density of the lead paste to a certain extent, thereby synchronously improving the density of the oxide layer between the lead paste and the grid to improve the adhesion between the lead paste and the grid and prevent the lead paste from falling off.

[0013] To achieve the above-mentioned purpose, the present application discloses a positive lead paste, which comprises at least the following components in terms of mass fraction:

[0014] Lead powder 80-90%;

[0015] Sulfuric acid 5-10%;

[0016] Pure water 3-9%;

[0017] Tetrabasic lead sulfate 0.2%–1%;

[0018] Polyaniline 0.1-0.5%;

[0019] Polytetrafluoroethylene 0.3-0.8%.

[0020] Preferably, sodium carboxymethyl cellulose and graphene are also added, wherein the amount of sodium carboxymethyl cellulose added is 0.05-0.15% of the total mass of the positive electrode lead paste;

[0021] The amount of graphene added is 0.01 to 0.1% of the total mass of the positive electrode lead paste.

[0022] Preferably, the graphene has a particle size of 5–200 μm.

[0023] Preferably, the graphene specifically includes large-particle-size graphene and small-particle-size graphene, wherein the particle size range of the large-particle-size graphene is 50–200 μm.

[0024] The particle size range of the small-diameter graphene is 5–50 μm, but does not include 50 μm;

[0025] The mass ratio of large-particle-size graphene to small-particle-size graphene is 1:2 to 4.

[0026] Preferably, the graphene contains graphene oxide, and the mass fraction of graphene oxide in the graphene is 30-60%.

[0027] In addition, this application also discloses a method for preparing the above-mentioned positive electrode lead paste, which involves mixing lead powder, sulfuric acid, pure water, tetrabasic lead sulfate, polyaniline and polytetrafluoroethylene to obtain the positive electrode lead paste.

[0028] Preferably, the procedure specifically includes the following steps:

[0029] Step 1: Add lead powder, tetrabasic lead sulfate, polyaniline, polytetrafluoroethylene, sodium carboxymethyl cellulose, and graphene to pure water and stir to obtain an intermediate;

[0030] Step 2: Introduce sulfuric acid into the intermediate and stir to obtain positive electrode lead paste.

[0031] In addition, this application also discloses a storage battery whose grid load has the positive electrode lead paste as described above.

[0032] The beneficial effects of this application are:

[0033] The lead paste provided in this application contains tetrabasic lead sulfate in its composition. This tetrabasic lead sulfate enhances the porous, mixed-structure α-PbO2 in the cathode material, thereby increasing the structural strength of the active material and reducing its shedding. More importantly, the addition of polyaniline and polytetrafluoroethylene further provides support to the cured lead paste, further improving its structural strength. The polyaniline filling also increases the internal density of the lead paste, thus simultaneously increasing the density of the oxide layer between the lead paste and the grid, thereby enhancing the bonding force between the lead paste and the grid and preventing lead paste shedding. Detailed Implementation

[0034] The present application will be clearly and completely described below with reference to its embodiments. It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0035] Before demonstrating the embodiments, the preparation and acquisition methods of the raw materials involved in the embodiments shall be explained as follows:

[0036] Lead powder: purchased from Qinghe County Nuotu Welding Materials Co., Ltd.;

[0037] Tetrabasic lead sulfate: purchased from Wuhan Jiyesheng Chemical Co., Ltd.;

[0038] Polyaniline: purchased from Wuhan Kemic Biomedical Technology Co., Ltd., with a molecular weight of 700±25;

[0039] Polytetrafluoroethylene (PTFE): Purchased from Dongguan Zhangmutou Jiamingrui Trading Department, PTFE dispersion (PTFE solid content 60±5wt%).

[0040] Sodium carboxymethyl cellulose: purchased from Guangzhou Yiming Chemical Co., Ltd.;

[0041] Graphene: Purchased from Shanghai Aladdin (large-diameter chemically reduced graphene; 1-100 micrometers) (amino-graphene; 100-200 nm).

[0042] A method for preparing positive electrode lead paste includes the following steps:

[0043] Step 1: Add lead powder, tetrabasic lead sulfate, polyaniline, polytetrafluoroethylene, sodium carboxymethyl cellulose, graphene and pure water into a paste mixer and stir for 12 minutes to obtain an intermediate;

[0044] Step 2: Pour sulfuric acid into the intermediate and turn on the paste mixer to stir again for 10 minutes to obtain positive electrode lead paste.

[0045] Examples 1-6

[0046] A positive electrode lead paste, the formula of which is shown in Table 1:

[0047] Table 1: Formulation table of positive electrode lead paste for Examples 1-6

[0048] Group Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Lead powder 80% 85.50% 89.80% 85.40% 85.40% 85.40% Sulfuric acid 10% 8% 6% 8% 8% 8% Pure water 9% 5% 3% 5% 5% 5% Tetraalkaline lead sulfate 0.40% 0.60% 0.40% 0.60% 0.60% 0.60% Polyaniline 0.10% 0.30% 0.50% 0.30% 0.30% 0.30% Polytetrafluoroethylene 0.50% 0.60% 0.30% 0.60% 0.60% 0.60% Sodium carboxymethyl cellulose 0 0 0 0.10% 0 0.05% Graphene 0 0 0 0 0.10% 0.05%

[0049] It should be noted that the graphene used in the above embodiments has a particle size range of 50 to 200 μm.

[0050] Example 7

[0051] The method is basically the same as in Example 6, except that the graphene includes large-particle graphene and small-particle graphene. The particle size range of the large-particle graphene is 50 to 200 μm, and the particle size range of the small-particle graphene is 5 to 50 μm, excluding 50 μm.

[0052] The mass ratio of large-particle-size graphene to small-particle-size graphene is 1:3.

[0053] Example 8

[0054] It is basically the same as Example 6, except that the particle size of the graphene is in the range of 5 to 50 μm and does not include 50 μm.

[0055] Example 9

[0056] It is basically the same as Example 6, except that graphene oxide is added to the graphene, wherein the mass fraction of graphene oxide in the graphene is 50%.

[0057] Comparative Examples 1-4

[0058] A type of lead paste, the formula of which is shown in Table 2:

[0059] Table 2: Formulation table of lead paste for comparative examples 1-4

[0060] Group Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Lead powder 85.50% 85.50% 85.40% 85.40% Sulfuric acid 8% 8% 8% 8% Pure water 5% 5% 5% 5% Tetraalkaline lead sulfate 0.60% 0.60% 0.60% 0.60% Polyaniline 0.90% 0 0.90% 0 Polytetrafluoroethylene 0 0.90% 0 0.90% Sodium carboxymethyl cellulose 0 0 0.05% 0.05% Graphene 0 0 0.05% 0.05%

[0061] Performance testing:

[0062] Test Example 1

[0063] The positive electrode lead paste prepared in the above embodiments and comparative examples is applied to the positive electrode grid, then cured, assembled and formed to obtain a storage battery;

[0064] Furthermore, it should be noted that the only difference between the batteries ultimately produced by the lead paste in the above embodiments and comparative examples is the different positive electrode lead paste. In addition, the negative electrode plate used in the battery is (produced by Guangdong Xuxin New Energy Technology Co., Ltd., with the following effective ingredient content: calcium (0.125~0.145%), tin (0.04~0.06%), aluminum (0.02~0.04%), and lead (to 100%).

[0065] The positive electrode plate is manufactured by Guangdong Xuxin New Energy Technology Co., Ltd., and the effective ingredient content is: calcium (0.08-0.09%), tin (1.18-1.25%), aluminum (0.02-0.04%), lanthanum (0.0095-0.011%), silver (0.0020-0.0025%), and lead (to 100%).

[0066] Referring to GB / T 22199.1-2017, the battery capacity of the batteries finally made from the lead paste of the above embodiments and comparative examples after 100 cycles, 200 cycles, 300 cycles, and 400 cycles was tested. The specific test results are shown in Table 3.

[0067] Table 3: Cyclic Performance Test Data Table

[0068] Group Battery capacity at 100 cycles / (Ah) Battery capacity at 200 cycles / (Ah) Battery capacity at 300 cycles / (Ah) Battery capacity at 400 cycles / (Ah) Example 1 24.32 22.51 21.03 19.35 Example 2 24.53 23.36 21.67 19.88 Example 3 24.65 22.83 21.54 19.25 Example 4 24.81 22.96 22.03 20.33 Example 5 25.03 23.66 22.12 20.37 Example 6 25.10 23.69 22.98 21.44 Example 7 24.90 23.85 22.91 21.42 Example 8 24.55 22.96 21.94 20.04 Example 9 25.32 23.77 23.10 21.37 Comparative Example 1 23.75 21.04 19.58 17.67 Comparative Example 2 23.53 20.87 19.34 17.48 Comparative Example 3 24.02 21.33 19.98 18.15 Comparative Example 4 23.74 21.03 19.81 17.99

[0069] Test Example 2

[0070] The test items are the same as those in Test Example 1. The difference is that the effective component content in the grid used in the battery manufacturing process is: antimony (0.125-0.145%), tin (0.04-0.06%), aluminum (0.02-0.04%), and lead (to 100%).

[0071] The specific test results are shown in Table 4:

[0072] Table 4: Cyclic Performance Test Data Table

[0073] Group Battery capacity at 100 cycles / (Ah) Battery capacity at 200 cycles / (Ah) Battery capacity at 300 cycles / (Ah) Battery capacity at 400 cycles / (Ah) Example 2 23.83 22.04 20.37 18.84 Comparative Example 1 23.61 21.54 20.36 18.25 Comparative Example 2 23.44 21.66 20.18 18.19

[0074] Results analysis:

[0075] 1. As can be seen from the observation of Examples 1-3, when the amount of raw materials added to the positive electrode lead paste is adjusted slightly, the capacity of 100-400 cycles in Examples 1-3 fluctuates, but the overall fluctuation range is relatively small.

[0076] 2. Further observation of Examples 4-6 shows that when sodium carboxymethyl cellulose or graphene is added to the lead paste, the cycling performance of Examples 4-5 is improved to a certain extent compared with Example 2, but the improvement is relatively small. Taking Example 2 as an example, its capacity after 400 cycles is reduced by 4.65 Ah compared with its capacity after 100 cycles, and the decay rate is about 18.96%.

[0077] Furthermore, similarly, the attenuation rates of Examples 4-5 were calculated to be approximately 18.05% and 18.62%, respectively. It can be seen that although the attenuation rate decreased, the magnitude was indeed small.

[0078] When sodium carboxymethyl cellulose and graphene were used simultaneously in Example 6, the attenuation rate was approximately 14.59%, which showed an improvement trend to varying degrees compared to Examples 2 and 4-5, and the improvement was relatively significant.

[0079] It is speculated that the reason for this phenomenon may be that the combined use of graphene and sodium carboxymethyl cellulose forms a "conductive-bonding" bifunctional system: on the one hand, graphene can enhance electron transport, and on the other hand, sodium carboxymethyl cellulose optimizes the ion conduction path, thereby synergistically reducing the battery's internal resistance and polarization loss, thus significantly improving the battery's cycle performance.

[0080] 3. As can be seen from Example 7, when the particle size of graphene is further changed, the cycle performance of Example 7 is improved to varying degrees compared with Example 2 and Example 8. In Example 9, after replacing the small-particle-size graphene with graphene oxide, the cycle performance is further slightly improved. It can be seen that the multi-particle-size mixed graphene additive can further enhance the electron transport capability.

[0081] 4. As can be seen from Example 2 and Comparative Examples 1-2, when polytetrafluoroethylene or polyaniline is lacking in the lead paste, the cycle performance of Comparative Examples 1-2 shows a certain degree of decline. When graphene or sodium carboxymethyl cellulose is added to the basis of Comparative Examples 1-2, Comparative Examples 3-4 show a certain degree of improvement compared to Comparative Examples 1-2, but their overall cycle performance is still not as good as that of Example 2. It can be seen that polytetrafluoroethylene and polyaniline have a very important influence on the cycle performance of lead paste.

[0082] 5. Further observation of Test Example 2 shows that when using grids with other components (grids with lead and antimony as the main components), the difference in cycle performance between Example 2 and Comparative Examples 1-2 is reduced. This indicates that the lead paste described in this application is more suitable for use with grids with lead and calcium as the main components.

Claims

1. A positive electrode lead paste, characterized in that, By mass fraction, it includes at least the following components: Lead powder 80-90%; Sulfuric acid 5-10%; Pure water 3-9%; Tetrabasic lead sulfate 0.2%–1%; Polyaniline 0.1-0.5%; Polytetrafluoroethylene 0.3-0.8%.

2. The positive electrode lead paste according to claim 1, characterized in that, Sodium carboxymethyl cellulose and graphene are also added, wherein the amount of sodium carboxymethyl cellulose added is 0.05-0.15% of the total mass of the positive electrode lead paste; The amount of graphene added is 0.01 to 0.1% of the total mass of the positive electrode lead paste.

3. The positive electrode lead paste according to claim 1, characterized in that, The graphene has a particle size of 5–200 μm.

4. The positive electrode lead paste according to claim 3, characterized in that, The graphene specifically includes large-particle-size graphene and small-particle-size graphene, wherein the particle size range of the large-particle-size graphene is 50–200 μm. The particle size range of the small-diameter graphene is 5 to 50 μm, but does not include 50 μm; The mass ratio of large-particle-size graphene to small-particle-size graphene is 1:2 to 4.

5. The positive electrode lead paste according to claim 2, characterized in that, The graphene contains graphene oxide, and the mass fraction of graphene oxide in the graphene is 30-60%.

6. A method for preparing the positive electrode lead paste according to any one of claims 1-5, characterized in that, Lead powder, sulfuric acid, pure water, tetrabasic lead sulfate, polyaniline, and polytetrafluoroethylene are mixed to obtain positive electrode lead paste.

7. The method for preparing positive electrode lead paste according to claim 6, characterized in that, Specifically, the following steps are included: Step 1: Add lead powder, tetrabasic lead sulfate, polyaniline, polytetrafluoroethylene, sodium carboxymethyl cellulose, and graphene to pure water and stir to obtain an intermediate; Step 2: Introduce sulfuric acid into the intermediate and stir to obtain positive electrode lead paste.

8. A storage battery, characterized in that, Its grid load has the positive lead paste as described in any one of claims 1-5.