A low-temperature negative lead paste formulation and a method for preparing the same

Abstract

This invention discloses a low-temperature negative electrode lead paste formulation and its preparation method. The raw materials are as follows by weight percentage: lead powder: 82%-88%, barium sulfate: 5%-12%, sodium lignosulfonate: 0.2%-1.0%, humic acid: 0.5%-1.0%, carbon black: 1%-2%, expanded graphite: 1%-2%, graphene: 0.5%-1.5%, and deionized water: balance. A mixture of spherical lead powder and flake lead powder (spherical powder accounting for 60%-70%) is used. The high specific surface area of ​​the spherical lead powder improves the wettability of the electrolyte, while the layered structure of the flake lead powder increases the porosity. The synergistic effect of these two materials increases the porosity of the negative electrode active material to 65%-70% (compared to approximately 55%-60% in traditional lead paste), accelerating the dissolution of lead sulfate and the diffusion of Pb²⁺.

Description

Technical Field

[0001] This invention relates to the field of lead paste technology, and in particular to a low-temperature negative electrode lead paste formulation and its preparation method. Background Technology

[0002] The negative electrode active material of lead-acid batteries is mainly spongy lead (Pb), which is converted into lead sulfate (PbSO4) during discharge and reversed back to Pb during charging. However, low-temperature environments (especially -40°C to 0°C) significantly degrade the charge-discharge acceptance performance of the negative electrode.

[0003] Although existing technologies improve the performance of negative electrodes by adding additives such as sodium lignosulfonate (to inhibit sulfidation) and barium sulfate (to improve pore structure), they still suffer from problems such as rapid capacity decay and insufficient charging acceptance at extreme low temperatures, and cannot meet the needs of electric vehicles, energy storage equipment, fire emergency equipment and other scenarios in northern winters. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature negative electrode lead paste formulation and its preparation method. Through the synergistic effect of active material matrix optimization, high-dispersibility conductive agent compounding and low-temperature active additives, the charging acceptance, discharge capacity and cycle life of the negative electrode plate in low-temperature environment are significantly improved.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A low-temperature negative electrode lead paste formulation, the raw materials of which are as follows by weight percentage: lead powder: 82%-88%, barium sulfate: 5%-12%, sodium lignosulfonate: 0.2%-1.0%, humic acid: 0.5%-1.0%, carbon black: 1%-2%, expanded graphite: 1%-2%, graphene: 0.5%-1.5%, deionized water: balance.

[0006] Preferably, the expanded graphite has an interlayer spacing of 0.35-0.5 nm and a specific surface area of ​​300-500 m² / g.

[0007] Preferably, the graphene has a particle size of 1-5 μm and a specific surface area of ​​500-1000 m² / g.

[0008] Preferably, the lead powder is a composite of spherical lead powder and flake lead powder, with spherical lead powder accounting for 60%-70% and flake lead powder accounting for 30%-40%; the average particle size of the spherical lead powder is 1-3 μm and the average particle size of the flake lead powder is 5-10 μm.

[0009] Preferably, the carbon black is one or a blend of acetylene black and Ketjen black, with acetylene black accounting for 60%-70% and Ketjen black accounting for 30%-40%.

[0010] This invention also provides a method for preparing low-temperature negative electrode lead paste, comprising the following steps: S1: Mix lead powder, barium sulfate, sodium lignosulfonate, carbon black, expanded graphite and graphene in a certain proportion and stir at 30-50 rpm for 10-15 minutes to obtain a premix. S2: Slowly add deionized water to the premix, control the temperature at 25-35℃, increase the stirring speed to 80-100 rpm, and stir for 20-30 minutes to obtain lead paste.

[0011] Compared with the prior art, the beneficial effects of the present invention are: 1. Optimization of active material matrix: Spherical lead powder and flake lead powder are used (60%-70% spherical). The high specific surface area of ​​spherical lead powder can improve electrolyte wettability, and the layered structure of flake lead powder can increase porosity. The two work together to increase the porosity of the negative electrode active material to 65%-70% (about 55%-60% in traditional lead paste), accelerating the dissolution of lead sulfate and the diffusion of Pb²⁺. 2. Highly dispersible conductive agent compound: The carbon black is a compound of acetylene black and Ketjen black (acetylene black accounts for 60%-70%). The high structure of acetylene black can form a three-dimensional conductive network, and the ultra-low resistivity of Ketjen black (≤8μΩ·m) can further improve the electron transfer efficiency. Expanded graphite (interlayer spacing 0.35-0.5 nm) is combined with graphene (particle size 1-5 μm). The layered structure of expanded graphite can adsorb lead sulfate crystals, inhibit sulfidation, and provide more reaction sites; graphene's high conductivity (conductivity ≥10) 4 S / m can accelerate electron transfer, and the two work together to increase the electronic conductivity of the negative electrode plate to 120-150 S / cm (compared to about 80-100 S / cm for traditional lead paste). 3. Synergistic effect of low-temperature active additives: Sodium lignosulfonate, as a sulfurization inhibitor, can form an adsorption film on the negative electrode surface to inhibit the excessive deposition of Pb²⁺ during charging; • The layered structure of expanded graphite and graphene can adsorb sulfate ions (SO4²⁻) in the electrolyte, reduce the nucleation energy barrier of lead sulfate at low temperature, promote the formation of fine-grained PbSO4, and reduce irreversible sulfidation. The composite conductive network of carbon black and graphene can reduce the internal resistance of the electrode, and the polarization voltage at -30℃ is reduced by 0.2-0.3V compared with traditional lead paste, significantly improving the charging acceptance capability (the measured charging current is increased by 20%-30%). Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example 1

[0013] A method for preparing a low-temperature negative electrode lead paste is as follows: The raw materials are weighed according to the following mass percentages: 52% spherical lead powder (average particle size 2μm), 36% flake lead powder (average particle size 8μm), 4% barium sulfate, 0.2% sodium lignosulfonate, 0.6% humic acid, 0.7% acetylene black, 0.3% Ketjen black, 1.5% expanded graphite, 1.0% graphene, and the remainder is deionized water; Add powder, barium sulfate, sodium lignosulfonate, acetylene black, Ketjen black, expanded graphite and graphene to a mixer and stir at 40 rpm for 12 minutes to obtain a premix. Slowly add deionized water (temperature controlled at 30℃) to the premix, increase the stirring speed to 90 rpm, and stir for 25 minutes to obtain lead paste. Example 2

[0014] The difference from Example 1 is that: spherical lead powder accounts for 65%, flake lead powder accounts for 35%; expanded graphite accounts for 1%, graphene accounts for 1.5%; acetylene black accounts for 70%, and Ketjen black accounts for 30%.

[0015] Performance testing The lead paste prepared in Examples 1-2 was coated onto the negative electrode grid (lead-calcium-tin alloy), cured, dried, and then assembled into a lead-acid battery. The battery was tested at -30°C, and the results are shown in the table below: index Example 1 Example 2 Control group (traditional lead paste) -40℃ discharge capacity retention rate (%) 82 85 58 -40℃ charging acceptance (A) 11 12 7 Cycle life (cycles, 80% DOD) 420 450 300 Test results show that the negative electrode plate prepared by the lead paste of the present invention has a discharge capacity retention rate of more than 40% at -30℃ compared with the control group, a charge acceptance rate of about 60%, and a cycle life of 40%, which is significantly better than the prior art.

[0016] This invention effectively solves the performance degradation problem of lead-acid battery negative electrode at low temperatures through the synergistic effect of active material matrix optimization, high dispersibility conductive agent compounding, and low-temperature active additives. It features strong charge acceptance, high capacity retention, and long cycle life, and is suitable for application scenarios in extreme low-temperature environments such as new energy vehicles and energy storage power stations.

[0017] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low temperature negative lead paste formulation characterized by: The raw materials are as follows by weight percentage: lead powder: 82%-88%, barium sulfate: 5%-12%, sodium lignosulfonate: 0.2%-1.0%, humic acid: 0.5%-1.0%, carbon black: 1%-2%, expanded graphite: 1%-2%, graphene: 0.5%-1.5%, deionized water: balance.

2. A low temperature negative lead paste formulation according to claim 1, characterized in that: The expanded graphite has an interlayer spacing of 0.35-0.5 nm and a specific surface area of ​​300-500 m² / g.

3. A low temperature negative lead paste formulation as claimed in claim 1, wherein: The graphene has a particle size of 1-5 μm and a specific surface area of ​​500-1000 m² / g.

4. The low temperature negative lead paste formulation of claim 1, wherein: The lead powder is a composite of spherical lead powder and flake lead powder, with spherical lead powder accounting for 60%-70% and flake lead powder accounting for 30%-40%; the average particle size of the spherical lead powder is 1-3μm and the average particle size of the flake lead powder is 5-10μm.

5. The low temperature negative lead paste formulation of claim 1, wherein: The carbon black is one or a blend of acetylene black and Ketjen black, with acetylene black accounting for 60%-70% and Ketjen black accounting for 30%-40%.

6. A method of preparing the low temperature negative lead paste of claim 1, characterized by: Includes the following steps: S1: Mix lead powder, barium sulfate, sodium lignosulfonate, carbon black, expanded graphite and graphene in a certain proportion and stir at 30-50 rpm for 10-15 minutes to obtain a premix. S2: Slowly add deionized water to the premix, control the temperature at 25-35℃, increase the stirring speed to 80-100 rpm, and stir for 20-30 minutes to obtain lead paste.