Rapid High-Temperature Vacuum Paste-Mixing Process for the Positive Electrode of Sealed Lead-Acid Batteries

Abstract

The present invention discloses a process for quickly preparing positive paste of a sealed lead-acid battery at high temperature under vacuum, belonging to the technical field of lead paste production and paste-making process for lead-acid batteries. The present invention adopts a three-stage paste-making process of dry mixing, wet mixing, and acid mixing, and uses a variety of substances such as needle coke powder, pre-oxidized fiber, tellurium dioxide, tribasic lead sulfate, and PTFE emulsion as lead paste additives, which can not only greatly increase the content of tribasic lead sulfate in the prepared lead paste, regulate the ratio of 3BS to 4BS, optimize the initial capacity and cycle life performance, but also does not require long-term high-temperature treatment during the preparation process and has high process stability, being suitable for industrial production and processing.

Description

Technical Field

[0001] The present invention belongs to the technical field of lead paste production and paste mixing process for lead-acid batteries, and particularly relates to a rapid high-temperature vacuum paste mixing process for the positive electrode of a sealed lead-acid battery. Background Art

[0002] Nowadays, large-scale industrialized storage batteries mainly include lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium-ion batteries. Among them, lead-acid batteries are still the most important secondary batteries due to their advantages such as low unit energy price, high recycling value, low comprehensive cost, and mature technology, and are widely used in many fields.

[0003] The fundamental purpose of preparing the positive electrode active material and negative electrode active material of a lead-acid battery is to produce lead paste particles with a certain shape and composition. As the precursor of the active material, the lead paste's structure will be inherited by the subsequent generated active material, so the preparation of the lead paste directly affects the battery performance. After paste mixing, the components in the whole lead paste include lead sub-sulfate, tribasic lead sulfate, lead oxide, metallic lead, lead hydroxide, etc. When using traditional lead powder as the electrode material, the positive electrode material will be converted into tribasic lead sulfate and tetrabasic lead sulfate during the curing process; research shows that the cycle life of a lead-acid battery will increase with the increase in the content of tetrabasic lead sulfate in the positive electrode lead paste. Such an electrode has a stable conductive skeleton, which can reduce the softening and shedding of the positive electrode grid and thus significantly extend the battery cycle life.

[0004] The nucleation and growth process of tetrabasic lead sulfate crystals in the lead paste is very sensitive to the paste mixing temperature. When the paste mixing temperature exceeds 85 - 90 °C, various phases in the lead paste quickly convert into tetrabasic lead sulfate. However, when using a high-temperature process to obtain a lead paste with a high content of tetrabasic lead sulfate, it often requires curing treatment at about 90 °C for several days, resulting in a significant increase in production costs; at the same time, due to the limitation of the cooling rate of traditional paste mixing equipment, a higher paste mixing temperature will also lead to a higher paste discharging temperature, which in turn affects the battery's service performance.

[0005] In view of this, it is necessary to study a rapid high-temperature vacuum paste mixing process for the positive electrode of a sealed lead-acid battery. Summary of the Invention

[0006] Aiming at the limitations of the temperature and equipment of the traditional paste mixing process mentioned in the background art, the purpose of the present invention is to provide a rapid high-temperature vacuum paste mixing process for the positive electrode of a sealed lead-acid battery. The present invention adopts a three-stage paste mixing process of dry mixing, wet mixing, and acid mixing, and uses a variety of additives for paste mixing, effectively overcoming the deficiencies of the existing paste mixing process, aiming to provide a new paste mixing process for lead-acid batteries with excellent service performance and long cycle life.

[0007] To achieve the above object, the present invention specifically adopts the following technical solutions:

[0008] The present invention provides a process for quickly high-temperature vacuum pasting the positive electrode of a sealed lead-acid battery, comprising the following steps:

[0009] Step 1): Add lead powder, needle coke, pre-oxidized fiber, tellurium dioxide, and tribasic lead sulfate additive into a paste mixer in sequence, and dry mix for 120 - 300 s to obtain a mixed powder material;

[0010] Step 2): Add PTFE emulsion and deionized water to the mixed powder material obtained in Step 1), and wet mix for 240 - 480 s to obtain a mixed wet material;

[0011] Step 3): Dropwise add sulfuric acid solution to the mixed wet material obtained in Step 2), control the acid addition rate while stirring and mixing, continue stirring after the sulfuric acid addition is completed, and take out the paste when the temperature of the lead paste is lower than 45 °C.

[0012] Preferably, the addition amount of the needle coke in Step 1) is 0.1% - 0.3% of the mass of the lead powder, and it needs to be pulverized into a powder with a particle size of 0.1 - 10 μm before addition. The purpose of adding needle coke in the present invention is to better adsorb the electrolyte, increase the penetration and contact between the electrolyte and the active material of the battery plate, and improve the utilization rate of the active material; ultimately, it can make up for the defect that the lead paste with a high content of tribasic lead sulfate affects the charge and discharge capacity of the lead-acid battery in the early stage.

[0013] Preferably, the addition amount of the pre-oxidized fiber in Step 1) is 1.2% - 3.0% of the mass of the lead powder. The purpose of adding pre-oxidized fiber in the present invention is to increase the porosity and strength of the active material of the plate, inhibit the shedding of the positive active material, and thereby extend the battery cycle performance.

[0014] Preferably, the addition amount of the tellurium dioxide in Step 1) is 0.04% - 0.15% of the mass of the lead powder. The present invention uses tellurium dioxide as a lead paste additive, which can coordinate the nucleation reaction of tribasic lead sulfate, control the crystal size and distribution of the generated tribasic lead sulfate, improve the crystal form, and adjust the content ratio of tribasic lead sulfate in the obtained lead paste.

[0015] Preferably, the particle size of the tribasic lead sulfate in the tribasic lead sulfate additive in Step 1) does not exceed 100 nm, and its addition amount is 0.6% - 1.1% of the mass of the lead powder. The tribasic lead sulfate additive acts as a seed crystal, which can increase the conversion rate of tribasic lead sulfate to tribasic lead sulfate.

[0016] Preferably, the addition amount of the PTFE emulsion in step 2) is 2.0%-8.0% of the mass of the lead powder in step 1), and the addition amount of the deionized water in step 2) is 8.2%-11.0% of the mass of the lead powder in step 1); the particle size of the solid particles in the PTFE emulsion does not exceed 10 nm, and the concentration is 60%. Deionized water promotes lead oxidation and agglomeration, and adjusts the apparent density and consistency of the lead paste; the PTFE emulsion ensures the stable progress of the reaction during charge and discharge.

[0017] Preferably, in step 3), the addition rate of sulfuric acid is controlled so that sulfuric acid is added within 10-12 minutes; the sulfuric acid is a sulfuric acid solution with a density of 1.42 g / cm 3 .

[0018] Preferably, the acid addition and pasting in step 3) are carried out under vacuum conditions. While adding acid, the temperature is gradually increased. When the addition amount of sulfuric acid reaches 75%, the highest pasting temperature reaches 85±0.5 °C, and then it is kept at a constant temperature until the addition of sulfuric acid is completed and the heating is stopped.

[0019] Preferably, the obtained lead paste is coated on a plate to obtain a positive plate for the production of a sealed lead-acid battery.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] The present invention provides a process for rapid high-temperature vacuum pasting of the positive electrode of a sealed lead-acid battery. Using a variety of substances such as needle coke powder, pre-oxidized fiber, tellurium dioxide, tetrabasic lead sulfate, and PTFE emulsion as lead paste additives can not only greatly increase the content of tetrabasic lead sulfate in the prepared lead paste, regulate the ratio of 3BS to 4BS, optimize the initial capacity and cycle life performance, but also the preparation process does not require long-term high-temperature treatment and has high process stability, making it suitable for industrial production and processing. Detailed Embodiments

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified for the manufacturer can be obtained as conventional products through commercial purchase.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0024] Example 1

[0025] A rapid high-temperature vacuum paste-making process for the positive electrode of a sealed lead-acid battery, comprising:

[0026] 1. Weigh 100 parts by weight of lead powder, 0.2 parts of needle coke powder, 2.5 parts of pre-oxidized fiber, 0.09 parts of tellurium dioxide, 1 part of tribasic lead sulfate additive, 6 parts of PTFE emulsion, 10 parts of deionized water, and 15 parts of

[0027] dilute sulfuric acid (density 1.42 g / cm 3 ) for standby.

[0028] 2. Add lead powder, needle coke powder, pre-oxidized fiber, tellurium dioxide, and tribasic lead sulfate additive to the paste mixer in sequence, and dry mix for 240 s to obtain a mixed powder; add PTFE emulsion and deionized water to the mixed powder, and wet mix for 400 s to obtain a mixed wet material; evacuate and continue to dropwise add sulfuric acid solution to the mixed wet material, control the acid addition rate (the sulfuric acid solution is added completely in 11 min), gradually raise the temperature at the same time (reach the highest temperature of 85 °C when the sulfuric acid addition amount reaches 3 / 4), and stir and paste. After the sulfuric acid addition is completed, stop heating and continue stirring. When the temperature of the lead paste drops to 44 - 45 °C, take out the paste.

[0029] Detect the composition of the lead paste prepared in this example: the free lead content is 1.1%; the 4BS content is 78%, and the 3BS content is 17%.

[0030] Example 2

[0031] A rapid high-temperature vacuum paste-making process for the positive electrode of a sealed lead-acid battery, comprising:

[0032] 1. Weigh 100 parts by weight of lead powder, 0.1 parts of needle coke powder, 3.0 parts of pre-oxidized fiber, 0.04 parts of tellurium dioxide, 1.1 parts of tribasic lead sulfate additive, 2 parts of PTFE emulsion, 11 parts of deionized water, and 15 parts of dilute sulfuric acid (density 1.42 g / cm 3 ) for standby.

[0033] 2. Add lead powder, needle coke powder, pre-oxidized fiber, tellurium dioxide, and tribasic lead sulfate additive to the paste mixer in sequence, and dry mix for 300 s to obtain a mixed powder; add PTFE emulsion and deionized water to the mixed powder, and wet mix for 400 s to obtain a mixed wet material; evacuate and continue to dropwise add sulfuric acid solution to the mixed wet material, control the acid addition rate (the sulfuric acid solution is added completely in 11 min), gradually raise the temperature at the same time (reach the highest temperature of 85 °C when the sulfuric acid addition amount reaches 3 / 4), and stir and paste. After the sulfuric acid addition is completed, stop heating and continue stirring. When the temperature of the lead paste drops to 44 - 45 °C, take out the paste.

[0034] Detect the composition of the lead paste prepared in this example: the free lead content is 1.9%; the 4BS content is 73%, and the 3BS content is 20%.

[0035] Example 3

[0036] A rapid high-temperature vacuum pasting process for the positive electrode of a sealed lead-acid battery, comprising:

[0037] 1. Weigh 100 parts of lead powder, 0.3 part of needle coke powder, 1.2 parts of pre-oxidized fiber, 0.15 part of tellurium dioxide, 0.6 part of tribasic lead sulfate additive, 8 parts of PTFE emulsion, 8.2 parts of deionized water, and 15 parts of dilute sulfuric acid (density 1.42 g / cm 3 ) for standby.

[0038] 2. Add lead powder, needle coke powder, pre-oxidized fiber, tellurium dioxide, and tribasic lead sulfate additive into the paste mixer in sequence, and dry mix for 200 s to obtain mixed powder; add PTFE emulsion and deionized water to the mixed powder, and wet mix for 280 s to obtain mixed wet material; evacuate and continue to drip sulfuric acid solution into the mixed wet material, control the acid addition speed (the sulfuric acid solution is added completely in 12 min), gradually increase the temperature at the same time (when the sulfuric acid addition amount reaches 3 / 4, the highest temperature reaches 85 °C), and stir and paste. After the sulfuric acid is added completely, stop heating and continue stirring. When the temperature of the lead paste drops to 44 - 45 °C, take out the paste.

[0039] Detect the composition of the lead paste prepared in this example: the free lead content is 1.6%; the 4BS content is 76%, and the 3BS content is 19%.

[0040] Comparative Example 1

[0041] A rapid high-temperature vacuum pasting process for the positive electrode of a sealed lead-acid battery, comprising:

[0042] 1. Weigh 100 parts of lead powder, 0.2 part of needle coke powder, 2.5 parts of pre-oxidized fiber, 1 part of tribasic lead sulfate additive, 6 parts of PTFE emulsion, 10 parts of deionized water, and 15 parts of dilute sulfuric acid (density 1.42 g / cm 3 ) for standby.

[0043] 2. Add lead powder, needle coke powder, pre-oxidized fiber, and tribasic lead sulfate additive into the paste mixer in sequence, and dry mix for 240 s to obtain mixed powder; add PTFE emulsion and deionized water to the mixed powder, and wet mix for 400 s to obtain mixed wet material; evacuate and continue to drip sulfuric acid solution into the mixed wet material, control the acid addition speed (the sulfuric acid solution is added completely in 11 min), gradually increase the temperature at the same time (when the sulfuric acid addition amount reaches 3 / 4, the highest temperature reaches 85 °C), and stir and paste. After the sulfuric acid is added completely, stop heating and continue stirring. When the temperature of the lead paste drops to 44 - 45 °C, take out the paste.

[0044] Detect the composition of the lead paste prepared in this comparative example: the free lead content is 2.8%; the 4BS content is 61%, and the 3BS content is 29%.

[0045] Comparative Example 2

[0046] A rapid high-temperature vacuum paste-making process for the positive electrode of a sealed lead-acid battery, comprising:

[0047] 1. Weigh 100 parts of lead powder, 0.2 parts of acicular coke powder, 2.5 parts of pre-oxidized fiber, 0.3 parts of tellurium dioxide, 1 part of tribasic lead sulfate additive, 6 parts of PTFE emulsion, 10 parts of deionized water, and 15 parts

[0048] dilute sulfuric acid (density 1.42 g / cm 3 ) for standby.

[0049] 2. Add lead powder, acicular coke powder, pre-oxidized fiber, tellurium dioxide, and tribasic lead sulfate additive into the paste mixer in sequence, and dry-mix for 240 s to obtain mixed powder; add PTFE emulsion and deionized water into the mixed powder, and wet-mix for 400 s to obtain mixed wet material; evacuate and continue to dropwise add sulfuric acid solution to the mixed wet material, control the acid addition speed (the sulfuric acid solution is added completely in 11 min), gradually increase the temperature at the same time (when the sulfuric acid addition amount reaches 3 / 4, the highest temperature is 85 °C), and stir and paste. After the sulfuric acid is added completely, stop heating and continue stirring. When the temperature of the lead paste drops to 44 - 45 °C, take out the paste.

[0050] Detect the composition of the lead paste prepared in this comparative example: the free lead content is 1.7%; the 4BS content is 86%, and the 3BS content is 9%.

[0051] Test Example

[0052] Conduct actual detection on the lead paste samples prepared in the above-mentioned examples and comparative examples:

[0053] Take the lead paste prepared in Examples 1 - 3 and Comparative Examples 1 - 2, coat it on the positive electrode grid according to the same process parameters, and then transfer it to indoor high-temperature curing: the first-stage temperature is 80 °C, the humidity is 96%, and the time is 8 h; the second-stage temperature is 50 °C, the humidity is 55%, and the time is 3 h; the third-stage temperature is 85 °C, the humidity is 25%, and the time is 11 h. Assemble the positive electrodes obtained after high-temperature curing into sealed lead-acid batteries and conduct performance detection under the same conditions. The results are shown in Table 1.

[0054] Table 1

[0055]

[0056] The above-described embodiments only represent several preferred embodiments of the present invention. The description is relatively specific and detailed, but it does not limit the present invention. It should be noted that for those skilled in the art, the present invention can also have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the concept and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid high-temperature vacuum pasting process for the positive electrode of a sealed lead-acid battery, characterized in that It includes the following steps: Step 1): Add lead powder, needle coke, pitch-based carbon fiber, tellurium dioxide, and tribasic lead sulfate additive into the paste mixer in sequence, and dry mix for 120 - 300 s to obtain mixed powder materials; Among them, the addition amount of the tellurium dioxide is 0.04% - 0.15% of the mass of the lead powder, the particle size of the tribasic lead sulfate in the tribasic lead sulfate additive does not exceed 100 nm, and its addition amount is 0.6% - 1.1% of the mass of the lead powder; Step 2): Add PTFE emulsion and deionized water into the mixed powder materials obtained in Step 1), and wet mix for 240 - 480 s to obtain mixed wet materials; Step 3): Dropwise add sulfuric acid solution into the mixed wet materials obtained in Step 2), control the acid addition rate while stirring and mixing, continue stirring after the sulfuric acid addition is completed, and take out the paste when the temperature of the lead paste is lower than 45°C; Among them, the acid addition and pasting in Step 3) are carried out under vacuum conditions, and the temperature is gradually increased while adding acid. When the addition amount of sulfuric acid is 75%, the highest pasting temperature reaches 85 ± 0.5°C, and then keep the temperature constant until the heating stops after the sulfuric acid addition is completed.

2. The rapid high-temperature vacuum paste-making process for the positive electrode of a sealed lead-acid battery according to claim 1, characterized in that, The addition amount of the needle coke described in Step 1) is 0.1% - 0.3% of the mass of the lead powder, and it needs to be crushed into powder with a particle size of 0.1 - 10 μm before addition.

3. The rapid high-temperature vacuum paste-making process for the positive electrode of the sealed lead-acid battery according to claim 1, characterized in that, The addition amount of the pitch-based carbon fiber described in Step 1) is 1.2% - 3.0% of the mass of the lead powder.

4. The rapid high-temperature vacuum paste-making process for the positive electrode of a sealed lead-acid battery according to claim 1, characterized in that, The addition amount of the PTFE emulsion described in Step 2) is 2.0% - 8.0% of the mass of the lead powder in Step 1), and the addition amount of the deionized water described in Step 2) is 8.2% - 11.0% of the mass of the lead powder in Step 1); the particle size of the solid particles in the PTFE emulsion does not exceed 10 nm.

5. The rapid high-temperature vacuum pasting process for the positive electrode of the sealed lead-acid battery according to claim 1 is characterized in that, Control the acid addition rate in Step 3) so that the sulfuric acid is added within 10 - 12 min.

6. The rapid high-temperature vacuum paste-making process for the positive electrode of the sealed lead-acid battery according to claim 1, characterized in that, The obtained lead paste is coated on the plate to obtain a positive plate for the production of a sealed lead-acid battery.

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