Positive electrode lead paste and positive electrode plate

Abstract

The invention relates to positive lead paste, which is used for a closed valve-regulated lead-acid battery and comprises lead powder, dilute sulphuric acid liquid, short fibers and a conductive carbon material without a layered structure. When the total amount of the positive lead paste is 100 wt%, the content of the conductive carbon material without the layered structure is 0.05 wt% to 0.5 wt%. The invention also provides a positive plate comprising the positive lead plaster and a conductive grid. As the conductive carbon material without the layered structure does not generate a volume expansion phenomenon due to contact with sulfuric acid in the charge-discharge process of the closed valve-regulated lead-acid battery, the condition that the conductive carbon material is broken and falls off from the conductive grid is avoided, and the charge-discharge cycle index of the closed valve-regulated lead-acid battery is increased, so that the service life of the closed valve-regulated lead-acid battery is prolonged. The positive lead paste can endow the closed valve adjusting type lead-acid battery with the advantage of long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrode material and an electrode, in particular to a positive electrode paste and a positive electrode plate. BACKGROUND

[0002] The active material of the positive electrode commonly used in lead-acid batteries contains lead dioxide and flaky graphite, and the electrolyte of the lead-acid battery includes sulfuric acid.

[0003] Because the flaky graphite will swell in volume when it contacts sulfuric acid, it will fall off the conductive grid of the lead-acid battery after long-term use, making it difficult to maintain the capacity of the lead-acid battery above 80%, thereby reducing the number of charge-discharge cycles of the lead-acid battery, and thus the lead-acid battery has the shortcoming of short service life. SUMMARY

[0004] An object of the present application is to provide a positive electrode paste.

[0005] The positive electrode paste of the present application is used in a valve regulated lead battery or a sealed lead-acid battery, and contains lead powder, dilute sulfuric acid solution, short fibers, and conductive carbon material without a layered structure, wherein the content of the conductive carbon material without a layered structure is 0.05wt% to 0.5wt% based on 100wt% of the total amount of the positive electrode paste.

[0006] The positive electrode paste of the present application, wherein the content of the conductive carbon material without a layered structure is 0.1wt% to 0.5wt% based on 100wt% of the total amount of the positive electrode paste.

[0007] The positive electrode paste of the present application, wherein the conductive carbon material without a layered structure is mesophase graphite carbon microspheres.

[0008] The positive electrode paste of the present application, wherein the content of the lead powder is 75wt% to 85wt% based on 100wt% of the total amount of the positive electrode paste.

[0009] The positive electrode paste of the present application, wherein the concentration of sulfuric acid in the dilute sulfuric acid solution is 1.20g / cm 3 to 1.35g / cm 3 .

[0010] The positive electrode paste of the present application, wherein the content of the dilute sulfuric acid solution is 10wt% to 20wt% based on 100wt% of the total amount of the positive electrode paste.

[0011] The positive lead paste of the present application contains the short fiber in an amount of 0.05 to 0.4 wt% based on 100 wt% of the total amount of the positive lead paste.

[0012] The positive lead paste of the present application further contains water.

[0013] The positive lead paste of the present application contains the water in an amount of 4 to 8 wt% based on 100 wt% of the total amount of the positive lead paste.

[0014] Another object of the present application is to provide a positive plate.

[0015] The positive plate of the present application contains the conductive grid and the above-mentioned positive lead paste disposed on the conductive grid.

[0016] The positive lead paste of the present application has the advantage that the conductive carbon material without the layered structure does not have the volume expansion phenomenon due to the contact with sulfuric acid during the charge and discharge of the sealed valve-regulated lead-acid battery, so that the conductive carbon material does not have the situation of being broken and falling off, and thus the number of charge and discharge cycles of the sealed valve-regulated lead-acid battery is improved, and thus the positive lead paste of the present application can provide the sealed valve-regulated lead-acid battery with the advantage of long service life. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a photograph showing the morphology and size of mesophase graphite carbon microspheres before contacting sulfuric acid;

[0018] Figure 2 is a photograph showing the morphology and size of mesophase graphite carbon microspheres after contacting sulfuric acid;

[0019] Figure 3 is a photograph showing the morphology and size of flaky graphite before contacting sulfuric acid;

[0020] Figure 4 is a photograph showing the morphology and size of flaky graphite after contacting sulfuric acid;

[0021] Figure 5 is a photograph showing whether the positive lead paste containing mesophase graphite carbon microspheres in the positive plate of the embodiment of the present application falls off after charge and discharge;

[0022] Figure 6 is a photograph showing whether the positive lead paste containing flaky graphite in the positive plate of Comparative Example 2 falls off after charge and discharge. DETAILED DESCRIPTION

[0023] The content of the present application will be described in detail below.

[0024] The positive plate of the present application has a conductive grid and two layers of lead paste respectively arranged on two opposite sides of the conductive grid. Each layer of lead paste includes positive lead paste, and the positive lead paste contains lead powder, dilute sulfuric acid solution, short fibers and conductive carbon material without layered structure. The content of the conductive carbon material without layered structure is 0.05wt% to 0.5wt% based on 100wt% of the total amount of the positive lead paste.

[0025] <Conductive grid>

[0026] The conductive grid is, for example, a lead grid or a lead alloy grid, etc.

[0027] <Lead powder>

[0028] In some embodiments of the present application, the lead powder has a density of 0.8g / cm 3 to 2.0g / cm 3 and an oxidation degree of 70% to 80%. The lead powder contains, for example, lead oxide. In some embodiments of the present application, the content of the lead powder is 75wt% to 85wt% based on 100wt% of the total amount of the positive lead paste.

[0029] <Dilute sulfuric acid solution>

[0030] The dilute sulfuric acid solution contains, for example, an aqueous solution of dilute sulfuric acid containing sulfuric acid and water. In some embodiments of the present application, the concentration of sulfuric acid in the dilute sulfuric acid solution is 1.20g / cm 3 to 1.35g / cm 3 . In some embodiments of the present application, the content of the dilute sulfuric acid solution is 10wt% to 20wt% based on 100wt% of the total amount of the positive lead paste.

[0031] <Short fibers>

[0032] In some embodiments of the present application, the length of the short fibers is 2mm to 5mm. The short fibers are, for example, but not limited to, polyester fibers, polypropylene fibers or polyacrylic fibers, etc. In some embodiments of the present application, the content of the short fibers is 0.05wt% to 0.4wt% based on 100wt% of the total amount of the positive lead paste.

[0033] <Conductive carbon material without layered structure>

[0034] The conductive carbon material without layered structure is, for example, but not limited to, mesophase graphite carbon microspheres, etc. In some embodiments of the present application, the conductive carbon material without layered structure is mesophase graphite carbon microspheres. In some embodiments of the present application, the content of the conductive carbon material without layered structure is 0.1wt% to 0.5wt% based on 100wt% of the total amount of the positive lead paste. The conductive carbon material without layered structure has a specific surface area of 3.8m 2a specific surface area of 1,000 m2 / g or more and an electrical conductivity of 700 S / cm or more. In some embodiments of the present application, the content of the conductive carbon material having no layered structure is 0.05% to 0.5% of the content of the lead powder.

[0035] In some embodiments of the present application, the positive lead paste further comprises water. The water is used to adjust the fluidity of the positive lead paste. In some embodiments of the present application, the content of the water is 4% to 8% by weight, based on the total amount of the positive lead paste as 100% by weight.

[0036] The present application will be further described in terms of the following examples, but it should be understood that the examples are merely illustrative and should not be construed as limiting the scope of the present application.

[0037] Example 1 Positive Lead Paste and Positive Plate

[0038] 84.6% by weight of lead powder (particle size: 1.2 ± 0.3 μm; composition: lead oxide; density: 0.9 ± 0.1 g / cm3; oxidation degree: 75 ± 5%), 0.2% by weight of polypropylene short fiber (length: 3 ± 1 mm), 0.1% by weight of interphase graphite carbon microspheres (specific surface area: 3.8 m2 / g; particle size: 3.5 ± 1.5 μm), and 4.7% by weight of water were subjected to a kneading treatment at 30°C, while 10.4% by weight of dilute sulfuric acid solution (containing sulfuric acid and water, the concentration of the sulfuric acid being 1.26 g / cm3) was divided into several portions and added in several portions during the kneading treatment, to obtain a positive lead paste. 3 2 3

[0039] The positive lead paste was coated on both opposite sides of a conductive grid (material: lead calcium tin alloy) using a doctor blade to form two layers of coating, and then was left to stand in an environment of 80°C and 95% relative humidity to perform a maturation treatment, followed by a drying treatment at 80°C to obtain a positive plate comprising two layers of lead paste and a conductive grid. The thickness of the lead paste layer was 2.5 ± 0.5 mm.

[0040] Examples 2 to 3 and Comparative Examples 1 to 4

[0041] Examples 2 to 3 and Comparative Examples 1 to 4 were performed in the same procedures as Example 1, except that the types and amounts of the components were changed, as shown in Table 1.

[0042] Evaluation Items

[0043] ​​​(1) State observation after contacting sulfuric acid: The appearance of mesophase graphite carbon microspheres and flaky graphite before and after contacting sulfuric acid was observed at 1000 times magnification using a scanning electron microscope (SEM) and photographed, and the results are shown in Figures 1 to 4 .

[0044] (2) Positive lead paste shedding state observation of positive plate after charge and discharge: The results are shown in Figures 5 to 6 .

[0045] (3) Discharge capacity (unit: mAh / g) and final charge and discharge cycle number measurement: The positive plate, negative plate [containing negative lead paste and conductive grid (material: lead calcium tin alloy)], separator film (material: AGM glass fiber) with a thickness of 1.5 mm, and 52.6 mL of sulfuric acid solution (containing sulfuric acid and water, and the concentration of sulfuric acid is 1.23 g / cm 3 ) of Examples 1 to 3 and Comparative Examples 1 to 4 were assembled into a combination to be formed, and then the combination to be formed was subjected to a formation treatment for 21.8 hours under the condition of 30±2℃, to form a lead-acid battery. The preparation method of the negative lead paste is to add water to a mixture containing lead oxide, polypropylene acid short fibers, barium sulfate, carbon conductive material (composition: conductive carbon black), and organic compound for inhibiting coarsening (composition: modified lignin sulfonic acid), and to perform a mixing treatment under the condition of 30℃, and at the same time, during the mixing treatment, dilute sulfuric acid solution (containing sulfuric acid and water, and the concentration of sulfuric acid is 1.26 g / cm 3 ). A charge and discharge instrument (source: Chroma; model: 17011) was used to measure the lead-acid battery under the conditions of 25±3℃ and 50±5% relative humidity, in constant voltage (CC-CV) charging mode and constant current (CC) discharging mode. The discharge rate is 3C of the rated capacity and the discharge current is 25.5A. The measurement results of the discharge capacity and the final charge and discharge cycle number are shown in Table 1. The final charge and discharge cycle number refers to the charge and discharge cycle number when the discharge capacity of the lead-acid battery decreases to 60% of the first discharge capacity under the charge and discharge cycle.

[0046] Referring to Figure 1 and Figure 2 , the mesophase graphite carbon microspheres before and after contacting sulfuric acid have irregular shapes, and the particle size is about 3.5 μm, so it can be seen that the morphology and size of the mesophase graphite carbon microspheres before and after contacting sulfuric acid do not change, which indicates that the mesophase graphite carbon microspheres do not have the problem of volume expansion after contacting sulfuric acid, leading to fragmentation. Referring to Figure 5 , the positive lead paste of the positive plate does not shed from the conductive grid after charge and discharge.

[0047] Referring to Figure 3 and Figure 4 The size of the flaky graphite is about 500 μm before contacting sulfuric acid, and the size of the flaky graphite is about 150 μm after contacting sulfuric acid, which indicates that the flaky graphite will expand in volume and cause the problem of fragmentation when contacting sulfuric acid. Referring to Figure 6 After charging and discharging, the positive lead paste of the positive plate will fall off from the conductive grid.

[0048] Table 1

[0049]

[0050]

[0051] Referring to Table 1, when the positive lead paste of the present application is used in a lead-acid battery, the lead-acid battery can maintain the capacity of 85% or more of the first discharge capacity when the number of charge and discharge cycles of the lead-acid battery under high-rate current (3C) discharge is 200 times or more. Therefore, it can be seen that the positive lead paste of the present application can indeed endow the lead-acid battery with the advantage of long service life.

[0052] In summary, since the conductive carbon material without a layered structure will not expand when contacting sulfuric acid during the charging and discharging process of the sealed valve-regulated lead-acid battery, causing fragmentation and falling off, the number of charge and discharge cycles of the sealed valve-regulated lead-acid battery is improved. Therefore, the positive lead paste of the present application can endow the sealed valve-regulated lead-acid battery with the advantage of long service life, and thus can indeed achieve the purpose of the present application.

Claims

1. A positive electrode lead paste, characterized by, The positive electrode lead paste comprises: a lead powder, a dilute sulfuric acid solution, short fibers, and a conductive carbon material without a layered structure, wherein the content of the conductive carbon material without a layered structure is 0.05wt% to 0.5wt% based on 100wt% of the total amount of the positive electrode lead paste.

2. The positive lead paste of claim 1, characterized in that: The content of the conductive carbon material without a layered structure is 0.1wt% to 0.5wt% based on 100wt% of the total amount of the positive electrode lead paste.

3. The positive lead paste of claim 1, characterized by: The conductive carbon material without a layered structure is mesophase graphite carbon microspheres.

4. The positive lead paste of claim 1, characterized by: The content of the lead powder is 75wt% to 85wt% based on 100wt% of the total amount of the positive electrode lead paste.

5. The positive lead paste of claim 1, wherein: The concentration of sulfuric acid in the dilute sulfuric acid solution is 1.20 g / cm 3 to 1.35 g / cm 3 .

6. The positive lead paste of claim 1, wherein: The content of the dilute sulfuric acid solution is 10wt% to 20wt% based on 100wt% of the total amount of the positive electrode lead paste.

7. The positive lead paste of claim 1, wherein: The content of the short fibers is 0.05wt% to 0.4wt% based on 100wt% of the total amount of the positive electrode lead paste.

8. The positive lead paste of claim 1, characterized by: The positive electrode lead paste further comprises water.

9. The positive lead paste of claim 8, characterized in that: The content of the water is 4wt% to 8wt% based on 100wt% of the total amount of the positive electrode lead paste.

10. A positive plate characterized by, The positive electrode lead paste comprises: a conductive grid, and the positive electrode lead paste as claimed in any one of claims 1 to 9 disposed on the conductive grid.

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