Negative electrode lead paste additive, negative electrode lead paste as well as preparation method and application of negative electrode lead paste

Abstract

The invention provides a negative electrode lead paste additive, a negative electrode lead paste and a preparation method and application of the negative electrode lead paste. The negative electrode lead paste additive comprises barium sulfate and treated lead sulfate, and the treated lead sulfate is prepared by the following steps: (1) thoroughly discharging a waste battery to convert a negative electrode active substance into lead sulfate; (2) taking out the negative plate, and washing off the sulfuric acid electrolyte attached to the negative plate; and (3) separating active substances in the cleaned negative plate, drying, crushing, grinding and screening to obtain the treated lead sulfate. The treated lead sulfate added in the invention directly becomes a negative electrode chemical reaction product lead sulfate nucleation center when the negative electrode discharges, and the performance of the treated lead sulfate is superior to that of pure barium sulfate as the negative electrode nucleation center. The prepared treated lead sulfate enables the battery to be difficult to be reduced into spongy lead during charging, and the effectiveness of double nucleation centers (lead sulfate and barium sulfate) is kept.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a negative electrode lead paste additive, negative electrode lead paste, its preparation method and application. Background Technology

[0002] Lead-acid batteries discharge at high rates for short periods, and a higher operating voltage during operation results in higher output power. Therefore, these batteries require increased closed-circuit voltage during discharge to provide a better user experience.

[0003] A battery consists of several individual cells forming a single cell. The voltage of a single cell is determined by the difference between the positive and negative electrode potentials. Any change in the potential of any electrode will cause a change in the battery voltage. When a battery is discharged at a high rate for a short period, the potential change at the negative electrode is much greater than that at the positive electrode. This causes the battery voltage to drop rapidly in a closed circuit, resulting in a poor user experience. In more serious cases, it can even prevent the motor from functioning properly.

[0004] When lead-acid batteries discharge at high rates for short periods, the reaction products need to precipitate on highly dispersed lead sulfate crystal nuclei at the negative electrode. After charging, the negative electrode is composed of spongy lead, with very few highly dispersed lead sulfate crystal nuclei at the beginning of discharge, causing a rapid drop in negative electrode potential and a rapid decrease in individual cell voltage. To address this phenomenon, battery manufacturers add highly dispersed barium sulfate, a swelling agent, to the negative electrode paste to act as nucleation centers for lead crystals. However, under high-rate discharge, the closed-circuit voltage of the negative electrode still experiences a significant drop followed by a rise at the beginning of discharge.

[0005] For example, patent application CN109148889A discloses an additive for lead-acid battery negative electrode paste, which consists of the following components measured in mass percentages: 37-65% barium sulfate, 15-30% sodium lignosulfonate, 2.6-8% polyester staple fiber, and 17-35% mixed carbon material. This application uses barium sulfate as a recrystallization nucleus, present in the components, and this nucleus is isomorphous to lead sulfate during discharge. Because barium sulfate is highly dispersed in the negative electrode paste, it provides a large number of nuclei for lead sulfate during discharge, thereby inhibiting the formation of lead sulfate on the lead crystal surface, thus improving low-temperature discharge performance.

[0006] For example, patent application CN107230777A discloses a lead-acid battery paste, including a positive electrode paste and a negative electrode paste. The negative electrode paste includes the following components in parts by weight: 100 parts recycled lead powder, 12-24 parts red lead, 0.4-1 parts barium sulfate, 0.05-0.12 parts barium stearate, 0.12-0.17 parts sodium lignosulfonate, 0.2-0.4 parts humic acid, 0.1-0.15 parts semi-carbonized wood chips, 0.05-0.09 parts polyester short fiber, 0.2-0.4 parts modified graphene, 10-15 parts dilute sulfuric acid, and 12-17 parts deionized water.

[0007] Therefore, technical improvements are needed to solve the problem of rapid voltage drop in individual cells caused by the decrease in negative electrode potential during short-term discharge at high rates in lead-acid batteries. Summary of the Invention

[0008] To address the aforementioned technical problems in the prior art, this invention provides a negative electrode lead paste additive, a negative electrode lead paste, its preparation method, and its application.

[0009] This invention provides a negative electrode lead paste additive, comprising barium sulfate and treated lead sulfate, wherein the treated lead sulfate is prepared by the following steps: (1) Discharge the used battery completely to convert the negative electrode active material into lead sulfate; (2) Remove the negative electrode plate and wash away the sulfuric acid electrolyte adhering to the electrode plate; (3) Separate the active material from the cleaned negative electrode plate, and dry, crush, grind and sieve it to obtain the treated lead sulfate.

[0010] Preferably, the mass ratio of barium sulfate to treated lead sulfate is 6~8:0.4~0.6.

[0011] Preferably, in step (1), the method for completely discharging the waste battery is to continuously discharge the lead-acid battery with a constant resistance of 1~2 ohms for 2 days, and then switch to short circuit mode and continue discharging for more than 30 days.

[0012] Preferably, in step (3), the sieving is performed using an 80-100 mesh standard sieve.

[0013] The present invention also provides a lead-acid battery negative electrode lead paste formula, comprising lead powder, dilute sulfuric acid, pure water and additives. By weight, every 1000 parts of lead powder corresponds to the following additives: 2-4 parts of lignin, 2-4 parts of acetylene black, 0.7-1 parts of fiber and 0.4-0.6 parts of the above-mentioned negative electrode lead paste additives.

[0014] Preferably, by weight, every 1000 parts of lead powder corresponds to 76-86 parts of the dilute sulfuric acid, and every 1000 parts of lead powder corresponds to 114-116 parts of the pure water.

[0015] Preferably, the specific gravity of the dilute sulfuric acid is 1.35~1.45 g / ml.

[0016] This invention also provides a method for preparing lead paste for the negative electrode of a lead-acid battery, using the above-mentioned lead paste formula for the negative electrode of a lead-acid battery, the preparation method comprising the following steps: (1) Mix the lead powder and additives in the prescribed amount and stir evenly to obtain mixture A; (2) Add the prescribed amount of pure water and dilute sulfuric acid to the mixture A, stir evenly, and obtain the lead paste for the negative electrode of the lead-acid battery.

[0017] Preferably, the specific gravity of the lead paste for the negative electrode of the lead-acid battery is 4.35~4.45 g / cm³. 3 .

[0018] The present invention also provides a lead-acid battery negative electrode paste, which is prepared by the above-mentioned method for preparing lead-acid battery negative electrode paste.

[0019] The present invention also provides a negative electrode plate for a lead-acid battery, comprising a negative electrode grid and a negative electrode lead paste coated on the negative electrode grid, wherein the negative electrode lead paste is the aforementioned negative electrode lead paste for lead-acid batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The treated lead sulfate added to the negative electrode lead paste of this invention is highly dispersed and does not agglomerate, and can directly serve as the nucleation center for lead sulfate, a chemical reaction product of the negative electrode. During the preparation of the treated lead sulfate, a large amount of Pb in the negative electrode is consumed during over-discharge. The generated PbSO4 initially consists of fine crystal grains, which gradually fuse and grow during long-term static operation, forming a dense and hard orthorhombic crystal system—the specific surface area decreases sharply, the surface energy decreases, and the thermodynamic stability is greatly improved. The electric field force during charging is unlikely to destroy its crystal lattice, making it difficult for the treated lead sulfate to be reduced to spongy lead during battery charging. This maintains the effectiveness of the dual nucleation centers (lead sulfate and barium sulfate), and its performance is superior to using barium sulfate as the nucleation center of the negative electrode. Attached Figure Description

[0021] Figure 1 The discharge curve of the 6-MQ-7L battery in Test Example 1 is shown.

[0022] Figure 2 The discharge curve of the 6-FM-7 battery in Test Example 2 is shown.

[0023] Figure 3 The discharge curve of the 6-FM-17 battery in Test Example 3 is shown. Detailed Implementation

[0024] Example 1 The returned 6-MQ-7L used batteries (with a capacity less than 50% of the rated capacity after full charging, the same below) were continuously discharged for 2 days using a constant resistance of 1.5 ohms, and then discharged for another 30 days using a short circuit method. The negative electrode plate was removed from the battery and placed in a water tank. The negative electrode plate was then washed with running pure water until it was neutral. The active material of the negative electrode plate was dried, crushed and ground, and then passed through an 80-mesh sieve to obtain the lead sulfate for the required negative electrode additive.

[0025] 1 ton of negative electrode lead powder was mixed with 7.0 kg of barium sulfate, 3 kg of lignin, 3 kg of acetylene black, 0.85 kg of fiber, and 0.5 kg of negative electrode additive with lead sulfate. Then, 115 kg of pure water and 81 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.40 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-MQ-7L battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0026] The positive electrode plate for a 6-MQ-7L battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, coating, acid leaching, surface drying, curing, drying, sheet separation, and screening.

[0027] Three positive electrode plates and four negative electrode plates of a 6-MQ-7L battery are paired and assembled into a battery. After being charged with acid, a 6-MQ-7L battery is obtained.

[0028] Comparative Example 1 One ton of negative electrode lead powder was mixed with 7.0 kg of barium sulfate, 3 kg of lignin, 3 kg of acetylene black, and 0.85 kg of fiber. Then, 115 kg of pure water and 81 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.39 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-MQ-7L battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0029] The positive electrode plate for a 6-MQ-7L battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, coating, acid leaching, surface drying, curing, drying, sheet separation, and screening.

[0030] Three positive electrode plates and four negative electrode plates of a 6-MQ-7L battery are paired and assembled into a battery. After being charged with acid, a 6-MQ-7L battery is obtained.

[0031] Example 2 The returned 6-FM-7 used batteries were continuously discharged for 2 days using a constant resistance of 1 ohm, and then the discharge was continued for 60 days in a short-circuit mode. The negative electrode plates were then removed from the batteries and placed in a water tank to be washed with running pure water until they were neutral. The active material of the negative electrode plates was dried, crushed and ground, and then passed through a 90-mesh sieve to obtain the lead sulfate required for the negative electrode additive.

[0032] One ton of negative electrode lead powder was mixed with 6.0 kg of barium sulfate, 2 kg of lignin, 2 kg of acetylene black, 0.7 kg of fiber, and 0.6 kg of negative electrode additive with lead sulfate. Then, 114 kg of pure water and 76 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.45 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-FM-7 battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0033] The positive electrode plate of a 6-FM-7 battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, coating, acid leaching, surface drying, curing, drying, sheet separation and screening.

[0034] Three positive plates and four negative plates of a 6-FM-7 battery are paired and assembled into a battery, which is then charged with acid to obtain a 6-FM-7 battery.

[0035] Comparative Example 2 One ton of negative electrode lead powder was mixed with 6.0 kg of barium sulfate, 2 kg of lignin, 2 kg of acetylene black, and 0.7 kg of fiber. Then, 115 kg of pure water and 76 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.44 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-FM-7 battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0036] The positive electrode plate of a 6-FM-7 battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, coating, acid leaching, surface drying, curing, drying, sheet separation and screening.

[0037] Three positive plates and four negative plates of a 6-FM-7 battery are paired and assembled into a battery, which is then charged with acid to obtain a 6-FM-7 battery.

[0038] Example 3 The returned 6-FM-17 used batteries were continuously discharged for 2 days using a constant resistance of 2 ohms, and then switched to a short-circuit mode and continued to discharge for 45 days. The negative electrode plates were opened and removed, and placed in a water tank to be washed with running pure water until they were neutral. The active material of the negative electrode plates was dried, crushed and ground, and then passed through a 100-mesh sieve to obtain the required negative electrode additive, lead sulfate.

[0039] 1 ton of negative electrode lead powder was mixed with 8.0 kg of barium sulfate, 4 kg of lignin, 4 kg of acetylene black, 1.0 kg of fiber, and 0.4 kg of negative electrode additive with lead sulfate. Then, 116 kg of pure water and 86 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.35 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-FM-17 battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0040] The positive electrode plate of a 6-FM-17 battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, plate coating, acid leaching, surface drying, curing, drying, sheet separation and screening.

[0041] Four positive electrode plates and five negative electrode plates of a 6-FM-17 battery are paired and assembled into a battery. After being charged with acid, a 6-FM-17 battery is obtained.

[0042] Comparative Example 3 One ton of negative electrode lead powder was mixed with 8.0 kg of barium sulfate, 4 kg of lignin, 4 kg of acetylene black, and 1.0 kg of fibrous lead. Then, 115 kg of pure water and 86 kg of dilute sulfuric acid paste with a specific gravity of 1.40 g / ml were added to obtain an apparent specific gravity of 4.36 g / cm³. 3 The negative electrode lead paste is applied to the negative grid of the cast 6-FM-17 battery, and then subjected to acid leaching, surface drying, curing, drying, and sectional polishing to obtain the electrode plate.

[0043] The positive electrode plate of a 6-FM-17 battery was prepared by mixing 1T of positive lead powder with 2Kg of graphite, 0.1Kg of short fiber, 45Kg of sulfuric acid with a specific gravity of 1.40g / ml and 102Kg of pure water, followed by paste preparation, plate coating, acid leaching, surface drying, curing, drying, sheet separation and screening.

[0044] Four positive electrode plates and five negative electrode plates of a 6-FM-17 battery are paired and assembled into a battery. After being charged with acid, a 6-FM-17 battery is obtained.

[0045] Test Example 1 The 6-MQ-7L batteries prepared in Example 1 and Comparative Example 1 were left to stand at 25°C for more than 24 hours, and then discharged at 35A to 11.4V. The operating voltage was recorded every 10 seconds, and the measured data are shown in Table 1. Figure 1 .

[0046] Table 1 Test Example 2 The 6-FM-7 batteries prepared in Example 2 and Comparative Example 2 were left to stand at 25°C for more than 24 hours, and then discharged at 21A to 11.7V. The operating voltage was recorded every 10 seconds, and the measured data are shown in Table 2. Figure 2 .

[0047] Table 2 Test Example 3 The 6-FM-17 batteries prepared in Example 3 and Comparative Example 3 were left to stand at 25°C for more than 24 hours, and then discharged at a constant power of 500W. The discharge termination voltage was 10.50V. The operating voltage was recorded every 1 minute, and the measured data are shown in Table 3. Figure 3 .

[0048] Table 3 The data from Examples 1 and 2 and Comparative Examples 1 and 2 illustrate that adding a mixture of treated and improved lead sulfate and barium sulfate to the negative electrode increases the initial discharge voltage of the battery by about 0.2V at high rates, thus improving the initial discharge voltage of the battery at high rates.

[0049] In Example 3 and Comparative Example 3, the constant power discharge time of the medium battery at high rate was 1090s and 1035s, respectively. It can be seen that by adding barium sulfate and treated lead sulfate to the negative electrode, the constant power discharge time of the battery at high rate was extended by 5.3%.

Claims

1. A negative electrode lead paste additive, comprising barium sulfate and treated lead sulfate, characterized in that, The treated lead sulfate is prepared by the following steps: (1) Discharge the used battery completely to convert the negative electrode active material into lead sulfate; (2) Remove the negative electrode plate and wash away the sulfuric acid electrolyte adhering to the electrode plate; (3) Separate the active material from the cleaned negative electrode plate, and dry, crush, grind and sieve it to obtain the treated lead sulfate.

2. The negative electrode lead paste additive according to claim 1, characterized in that, The mass ratio of barium sulfate to treated lead sulfate is 6~8:0.4~0.

6.

3. The negative electrode lead paste additive according to claim 1, characterized in that, In step (1), the method to completely discharge the waste battery is to discharge the lead-acid battery continuously for 2 days using a constant resistor of 1~2 ohms, and then switch to short circuit mode and continue discharging for more than 30 days.

4. The negative electrode lead paste additive according to claim 1, characterized in that, In step (3), the sieving is performed using an 80-100 mesh standard sieve.

5. A lead-acid battery negative electrode lead paste formula, comprising lead powder, dilute sulfuric acid, pure water, and additives, characterized in that, By weight, each 1000 parts of lead powder corresponds to the following additives: 2-4 parts of lignin, 2-4 parts of acetylene black, 0.7-1 parts of fiber, and 0.4-0.6 parts of the negative electrode lead paste additives according to any one of claims 1-4.

6. The lead paste formula for the negative electrode of a lead-acid battery according to claim 5, characterized in that, By weight, every 1000 parts of lead powder corresponds to 76-86 parts of the dilute sulfuric acid, and every 1000 parts of lead powder corresponds to 114-116 parts of the pure water.

7. A method for preparing lead paste for the negative electrode of a lead-acid battery, characterized in that, The preparation method using the lead-acid battery negative electrode lead paste formulation according to any one of claims 5-6 includes the following steps: (1) Mix the lead powder and additives in the prescribed amount and stir evenly to obtain mixture A; (2) Add the prescribed amount of pure water and dilute sulfuric acid to the mixture A, stir evenly, and obtain the lead paste for the negative electrode of the lead-acid battery.

8. The method for preparing lead paste for the negative electrode of a lead-acid battery according to claim 7, characterized in that, The specific gravity of the lead paste for the negative electrode of the lead-acid battery is 4.35~4.45 g / cm³. 3 .

9. A lead paste for the negative electrode of a lead-acid battery, characterized in that, It is prepared by the method for preparing lead-acid battery negative electrode paste according to any one of claims 7 to 8.

10. A negative electrode plate for a lead-acid battery, comprising a negative electrode grid and negative electrode lead paste coated on the negative electrode grid, characterized in that, The negative electrode paste is the lead-acid battery negative electrode paste as described in claim 9.

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