An additive for positive electrodes of lead-acid batteries

Abstract

This application discloses a positive electrode additive for lead-acid batteries, relating to the field of lead-acid battery technology, comprising the following components by weight: modified 4BS; composite graphite fiber; core-shell structure: 5-12 parts, comprising a SiO2 core and an outer TiO2 shell; γ-Al2O3 nanosheets: 0.8-1.5 parts, with a sheet diameter of 80-120 nm and a thickness of 3-5 nm; through the composite application of core-shell structure nanoparticles and γ-Al2O3 nanosheets, the core-shell structure not only eliminates the aggregation of SiO2 through a physical isolation mechanism, but also promotes heterogeneous nucleation by utilizing the lattice matching between TiO2 and 4BS; the γ-Al2O3 nanosheets reduce thermal stress and stabilize the conduction band potential through thermal expansion coefficient compensation and aluminum ion doping effect, thereby improving the mechanical strength of the electrode plate, interface stability, and cycle life of the battery, achieving a comprehensive improvement in the performance of lead-acid batteries.

Description

Technical Field

[0001] This invention relates to the field of lead-acid batteries, and more particularly to a positive electrode additive for lead-acid batteries. Background Technology

[0002] In modern society, lead-acid batteries are widely used in automotive starting, energy storage, and backup power applications due to their low cost and mature technology. A lead-acid battery is a rechargeable battery. Its working principle is based on lead (Pb) and lead dioxide (PbO2) as active materials, which convert electrical energy into chemical energy through electrochemical reactions in an electrolyte. During discharge, the lead dioxide at the positive electrode and the lead at the negative electrode react with sulfuric acid in the electrolyte to produce lead sulfate and water. During charging, the lead sulfate is converted back into lead dioxide and lead through a reverse reaction, while sulfuric acid is electrolyzed out.

[0003] Authorized patent CN 115763815 B discloses a positive electrode and paste additive for lead-acid batteries. By introducing components such as modified 4BS, composite graphite fibers, and liquid-phase SiO2, it significantly improves the cycle life of lead-acid batteries. However, this patent still has limitations in solving the problem of nano-SiO2 particle agglomeration, failing to fundamentally eliminate the agglomeration phenomenon, and the interaction between additives may also affect its overall performance. Therefore, it is necessary to further explore new additive components and structures based on existing technologies to comprehensively improve the performance of lead-acid batteries. Summary of the Invention

[0004] This application provides a lead-acid battery positive electrode additive that effectively solves the problems of easy agglomeration of traditional nano-SiO2 particles and negative interactions between additives. By combining core-shell structured nanoparticles with γ-Al2O3 nanosheets, the core-shell structure not only eliminates the agglomeration of SiO2 through a physical isolation mechanism, but also promotes heterogeneous nucleation by utilizing the lattice matching of TiO2 and 4BS. Meanwhile, the γ-Al2O3 nanosheets reduce thermal stress and stabilize the conduction band potential through thermal expansion coefficient compensation and aluminum ion doping effect, significantly improving the mechanical strength of the electrode plate, interface stability, and cycle life of the battery, thus achieving a comprehensive improvement in the performance of lead-acid batteries.

[0005] This application provides a positive electrode additive for lead-acid batteries, comprising the following components in parts by weight:

[0006] Modified 4BS: 6-10 parts;

[0007] Composite graphite fiber: 6-13 parts;

[0008] Core-shell structure: 5-12 parts, wherein the core-shell structure includes a SiO2 core and a TiO2 shell covering it, wherein the SiO2 core has a particle size of 3.0±0.5 nm and the TiO2 shell has a thickness of 3.0±0.5 nm;

[0009] γ-Al2O3 nanosheets: 0.8-1.5 parts, with a sheet diameter of 80-120 nm and a thickness of 3-5 nm.

[0010] Furthermore, the core-shell structure is composed of fine and coarse particles;

[0011] The fine particles have a SiO2 core diameter of 3.0 ± 0.5 nm and a TiO2 shell thickness of 3.0 ± 0.5 nm.

[0012] The coarse particles have a SiO2 core diameter of 10.0±1.0 nm and a TiO2 shell thickness of 5.0±0.5 nm.

[0013] Furthermore, the weight ratio of the fine particles to the coarse particles is (6~7):(2~3).

[0014] Furthermore, the γ-Al2O3 nanosheets are subjected to isoelectric point regulation treatment, and their isoelectric point is pH=4.0±0.2.

[0015] A method for preparing a positive electrode additive for lead-acid batteries, characterized by comprising the following steps:

[0016] Step 1: Mix the core-shell structure with γ-Al2O3 nanosheets, add deionized water for ultrasonic dispersion, dry and grind to obtain a core-shell-alumina composite;

[0017] Step 2: Break the composite graphite fibers to a length of 50-100μm and mix them with modified 4BS.

[0018] Add the core-shell alumina composite obtained in step 1 and continue stirring to obtain the positive electrode additive.

[0019] Furthermore, in step 1, the conditions for ultrasonic dispersion are 40℃, 200W / L power, 40kHz frequency, and 20 minutes.

[0020] The drying conditions were vacuum drying at 80℃ for 6 hours, followed by grinding through a 300-mesh sieve.

[0021] Furthermore, in step 2, the mixing conditions with the modified 4BS are 80-120℃, 150rpm, and 60 minutes.

[0022] After adding the core-shell alumina composite, the stirring conditions are 80-120℃, 100rpm, and 30 minutes.

[0023] Furthermore, step 1 also includes electrical regulation treatment:

[0024] γ-Al2O3 nanosheets were calcined at 580±10℃ for 2 hours to adjust their isoelectric point to pH=4.0±0.2;

[0025] The dual-size core-shell structure was dispersed in a pH 6.0 buffer solution, and the zeta potential was measured to be -30±2mV. The modified γ-Al2O3 nanosheets were mixed with the dual-size core-shell structure, the pH was adjusted to 1.5±0.1, and the mixture was ultrasonically dispersed, dried and ground.

[0026] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0027] By introducing a core-shell structure and γ-Al₂O₃ nanosheets, a multi-level synergistic mechanism is generated to significantly improve the performance of lead-acid batteries. The core-shell structure physically isolates the aggregation of the silicon dioxide core with a titanium dioxide shell and guides the orderly growth of α-PbO₂ through lattice matching, thereby enhancing the mechanical strength of the plates. The alumina nanosheets reduce thermal stress and lower the conduction band potential through thermal expansion coefficient compensation and aluminum ion doping of the titanium lattice, thus blocking titanium dissolution. The synergistic effect of the two is manifested in: the formation of Al-O-Ti covalent bonds at the atomic scale to enhance interfacial bonding energy; the construction of a three-dimensional phonon thermal conduction network at the mesoscale to balance the temperature field; and the inhibition of acid etching and ion migration at the electrochemical level through charge balance.

[0028] By employing a dual-size core-shell structure in the positive electrode additive of lead-acid batteries and electrostatically pre-assembling it with γ-Al2O3 nanosheets with isoelectric point controlled, a multi-level and multi-dimensional synergy from hierarchical filling at the physical scale to strong bonding at the chemical interface is achieved, which enhances the mechanical strength, structural stability and electrochemical durability of the electrode plate, thereby significantly improving the cycle life and high and low temperature performance of the battery. Detailed Implementation

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Example 1: A positive electrode additive for lead-acid batteries, comprising the following components by weight: 6-10 parts modified 4BS, 6-13 parts composite graphite fiber, 5-12 parts core-shell structure, and 0.8-1.5 parts alumina nanosheets.

[0031] The core-shell structure comprises a SiO2 core with a particle size of 3.0 ± 0.5 nm, a TiO2 shell with a thickness of 3.0 ± 0.5 nm, and alumina nanosheets of γ-Al2O3 with a diameter of 80-120 nm, a thickness of 3-5 nm, and a specific surface area >200 m². 2 / g;

[0032] The method for preparing the core-shell structure is as follows:

[0033] SiO2 core synthesis: Tetraethyl orthosilicate (TEOS), anhydrous ethanol, and deionized water were mixed in a molar ratio of 1:4:8; the mixture was stirred at 5±1℃, and the pH was adjusted to 10.5-11.0 with ammonia water. The reaction was carried out for 60 minutes to obtain SiO2 sol with a particle size of 3.0±0.5 nm.

[0034] TiO2 coating: Tetrabutyl titanate (TBOT) and anhydrous ethanol are mixed at a volume ratio of 1:10; SiO2 sol is added dropwise and stirred at a constant temperature of 40±2℃ for 120 minutes; the dropping rate is controlled to ≤1 mL / min to prevent TiO2 self-aggregation;

[0035] Hydrothermal aging: Transfer to an autoclave and react at 120°C for 6 hours; cool to room temperature to form Ti-O-Si covalent bonds;

[0036] Supercritical drying: drying under supercritical CO2 conditions (40℃, 15 MPa); grinding through a 300-mesh sieve to obtain core-shell structured powder;

[0037] The preparation method of the γ-Al2O3 nanosheets is as follows:

[0038] Precursor synthesis: Aluminum sulfate and urea were dissolved in water at a molar ratio of 1:3; hydrothermal reaction was carried out at 90℃ for 8 hours to generate boehmite (AlOOH) nanosheet precursor;

[0039] Calcination transformation: Calcination in a muffle furnace at 550℃ for 3 hours (heating rate 5℃ / min); γ-Al2O3 nanosheets were obtained;

[0040] Surface modification: Treat with 2wt% polyethylene glycol (PEG-6000) ethanol solution; sonicate at 60℃ for 30 minutes, centrifuge, wash and dry;

[0041] The modified 4BS and composite graphite fiber were prepared using the method described in Example 1 of CN115763815B.

[0042] The preparation method of the lead-acid battery positive electrode additive is as follows:

[0043] Step 1: Pretreatment of core-shell structure and alumina nanosheets; The core-shell structure and alumina nanosheets are added to a mixer in the proportion of weight parts; Deionized water (twice the total weight of the two) is added, and the mixture is ultrasonically dispersed at 200 W / L power for 20 minutes (frequency 40 kHz) at 40℃ to form a uniform slurry; The slurry is vacuum dried at 80℃ for 6 hours, and then ground through a 300-mesh sieve to obtain the core-shell-alumina composite.

[0044] Step 2: Additive premixing; crush the composite graphite fibers to a length of 50-100 μm; add modified 4BS and stir at 80-120℃ and 150 rpm for 60 minutes; add the composite obtained in Step 1, maintain the temperature at 80-120℃, reduce the speed to 100 rpm and continue stirring for 30 minutes, cool the mixture to room temperature to obtain the positive electrode additive;

[0045] Step 3: Prepare the finished product; Take 1000 g of lead powder, add the premixed additive from Step 2 (addition amount 100-300 g), and dry mix for 30 minutes; slowly add 100 g of dilute sulfuric acid with a density of 1.40 g / cm³ and 100 g of deionized water; wet mix until the density reaches 4.2-4.5 g / cm³, and control the temperature below 45℃.

[0046] The experiment was conducted for this embodiment, and the experimental groups and parameters are shown in Table 1 below;

[0047] Table 1

[0048]

[0049] Experimental steps: Electrode preparation:

[0050] (1) Take 1000 g of lead powder and 100 g of additives, and dry mix for 30 minutes;

[0051] Add 100 g of dilute sulfuric acid (1.40 g / cm³) and 100 g of pure water and wet mix until the density is 4.3 g / cm³;

[0052] Curing of the coated grid (65℃, 95% humidity, 24h), followed by drying.

[0053] (2) Battery assembly: Add a positive plate, a negative plate, and an AGM separator to assemble a 12V 7Ah battery;

[0054] Injection solution (density 1.28 g / cm³ H2SO4), internalization (0.05C charge-discharge activation).

[0055] (3) Performance testing:

[0056] Cycle life: 0.2C discharge to 10.8V, 0.15C charge to 14.4V, cycle until 50% capacity decay;

[0057] Plate bending strength: Three-point bending method;

[0058] High-temperature performance: Capacity retention was measured at 0.2C charge and discharge in an environment of 60℃.

[0059] The test results are shown in Table 2 below;

[0060] Table 2

[0061]

[0062] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0063] By introducing a core-shell structure and γ-Al₂O₃ nanosheets, a multi-level synergistic mechanism is generated to significantly improve the performance of lead-acid batteries. The core-shell structure physically isolates the aggregation of the silicon dioxide core with a titanium dioxide shell and guides the orderly growth of α-PbO₂ through lattice matching, thereby enhancing the mechanical strength of the plates. The alumina nanosheets reduce thermal stress and lower the conduction band potential through thermal expansion coefficient compensation and aluminum ion doping of the titanium lattice, thus blocking titanium dissolution. The synergistic effect of the two is manifested in: the formation of Al-O-Ti covalent bonds at the atomic scale to enhance interfacial bonding energy; the construction of a three-dimensional phonon thermal conduction network at the mesoscale to balance the temperature field; and the inhibition of acid etching and ion migration at the electrochemical level through charge balance.

[0064] The core-shell structure uses silicon dioxide as the core (particle size 3.0±0.5 nm) and is covered with a titanium dioxide shell (thickness 3.0±0.5 nm). The titanium dioxide shell is covalently bonded to the silicon dioxide core to form a complete coating layer. This structure functions through a dual mechanism:

[0065] Physical isolation mechanism: The titanium dioxide shell isolates the silicon dioxide core from direct contact with the strong acid electrolyte, blocks the protonation reaction of silanol groups (Si-OH) on the silicon dioxide surface, and fundamentally inhibits the aggregation of nanoparticles caused by hydrogen bond bridging.

[0066] Lattice matching mechanism: The (101) crystal plane of the titanium dioxide shell and the (001) crystal plane of the modified 4BS seed crystal are highly compatible (lattice mismatch rate <3%). During the charging and discharging process, the titanium dioxide crystal plane guides the α-PbO2 crystal in the lead paste to grow along a specific orientation, forming a three-dimensional skeleton structure with higher mechanical strength, and the crystal order is significantly improved.

[0067] γ-phase alumina nanosheets (80-120 nm in diameter, 3-5 nm in thickness), after calcination at 550℃, have a surface rich in aluminum vacancy defects. Their core function is reflected in:

[0068] Thermal expansion coefficient compensation: The c-axis thermal expansion coefficient of the alumina nanosheets matches that of the titanium dioxide shell, while the a-axis expansion coefficient is significantly lower. When the temperature fluctuates, the alumina sheet layer counteracts the thermal expansion of titanium dioxide in the parallel direction and compensates for the cold contraction stress of the silicon dioxide core in the vertical direction, thus significantly reducing the overall thermal strain.

[0069] Lattice doping effect: Trivalent aluminum ions in alumina can be embedded in the titanium dioxide lattice, partially replacing the sites of tetravalent titanium ions. The doping behavior causes lattice contraction and simultaneously shifts the titanium dioxide conduction band position from -0.5V to -0.8V. This energy level adjustment blocks the titanium reduction reaction during deep discharge, and the titanium dissolution rate is significantly reduced.

[0070] The core-shell structure and alumina nanosheets achieve synergistic effects through interfacial bonding, lattice coupling, and charge transfer:

[0071] Atomic-scale bonding enhancement: Oxygen vacancies on the surface of alumina capture titanium ions from the titanium dioxide shell, forming stable Al-O-Ti covalent bonds. The bonding strength far exceeds that of traditional physical adsorption, and the interfacial binding energy is significantly improved during charge-discharge cycles, effectively inhibiting the shedding of active materials.

[0072] Mesoscale thermal stress reduction: Alumina nanosheets are interspersed between core-shell particles to construct a three-dimensional thermally conductive network. Their high-frequency phonon vibrations are coupled with the low-frequency phonons of titanium dioxide, which improves the thermal conductivity of the system and avoids thermal shock cracks during high-current discharge.

[0073] Electrochemical synergistic protection: The energy band of titanium dioxide induced by aluminum doping shifts downward and forms a charge balance system with the positive charge on the aluminum oxide surface. During the deep discharge stage, this system preferentially adsorbs hydrogen ions in the electrolyte, preventing them from eroding the silicon dioxide core, while also inhibiting the migration of titanium ions.

[0074] The synergistic system enables breakthroughs in the core performance of lead-acid batteries, improving cycle life, enhancing environmental adaptability, and strengthening structural stability.

[0075] Example 2: The above example, by introducing a core-shell structure and γ-Al₂O₃ nanosheets, significantly improves the performance of lead-acid batteries through a multi-level synergistic mechanism. The core-shell structure physically isolates the aggregation of the silicon dioxide core with a titanium dioxide shell and guides the orderly growth of α-PbO₂ through lattice matching, enhancing the mechanical strength of the plates. The alumina nanosheets, through thermal expansion coefficient compensation and aluminum ion doping of the titanium lattice, reduce thermal stress and lower the conduction band potential, blocking titanium dissolution. The synergy between the two results in the formation of Al-O-Ti covalent bonds at the atomic scale to enhance interfacial bonding energy, the construction of a three-dimensional phonon thermal conductivity network at the mesoscale to balance the temperature field, and the suppression of acid corrosion and ion migration at the electrochemical level through charge balance, achieving a breakthrough in lead-acid battery performance. To further improve the performance of lead-acid batteries, further improvements are made based on Example 1.

[0076] The core-shell structure includes fine and coarse particles;

[0077] The fine particles have a SiO2 core of 3.0 ± 0.5 nm and a TiO2 shell of 3.0 ± 0.5 nm; the coarse particles have a SiO2 core of 10.0 ± 1.0 nm and a TiO2 shell of 5.0 ± 0.5 nm.

[0078] The preparation of the coarse particles is specifically as follows:

[0079] Tetraethyl orthosilicate (TEOS), anhydrous ethanol, and deionized water were mixed in a molar ratio of 1:6:5.

[0080] Stirring at 25±2℃, adjusting the pH to 9.5-10.0 with ammonia, reacting for 90 minutes, yielding SiO2 sol with a particle size of 10.0±1.0nm;

[0081] Tetrabutyl titanate (TBOT) and anhydrous ethanol were mixed at a volume ratio of 1:15, and then added dropwise to the above SiO2 sol at a slower rate of ≤0.5 mL / min. The mixture was stirred at a constant temperature of 40 ± 2 °C for 150 minutes. (The slower dropping rate and lower concentration prevent TiO2 from self-aggregating when coating larger SiO2 surfaces.)

[0082] The mixture was transferred to an autoclave and reacted at 120°C for 8 hours (extending the reaction time to ensure the formation of a complete and dense TiO2 shell on the large particle size surface), and then cooled to room temperature.

[0083] Pretreatment and compounding of core-shell structure with alumina nanosheets

[0084] The fine-particle core-shell structure and the coarse-particle core-shell structure prepared above are mixed in a weight ratio of (6-7 parts): (2-3 parts), preferably in a ratio of 6:3 or 7:2.

[0085] The mixed dual-size core-shell structure and γ-Al2O3 nanosheets were fed into a mixer together;

[0086] Add deionized water (the mass of deionized water is 2.5 times the total mass of the core-shell structure and alumina nanosheets), and ultrasonically disperse at 50℃ with a power of 250 W / L for 30 minutes (frequency 40 kHz) to allow the core-shell structure with different particle sizes to fully interact with the sheet alumina and form a uniform composite slurry.

[0087] The slurry was vacuum dried at 80℃ for 6 hours, ground, and then passed through a 300-mesh sieve to obtain a dual-size core-shell alumina composite.

[0088] Additive premix:

[0089] The composite graphite fibers were broken into lengths of 50-100 μm.

[0090] The crushed composite graphite fibers were mixed with modified 4BS and stirred at 80-120℃ and 150 rpm for 60 minutes.

[0091] Add the dual-particle-size core-shell alumina composite, maintain the temperature at 80-120℃, reduce the speed to 100 rpm and continue stirring for 30 minutes to ensure that the additive components are evenly mixed.

[0092] The mixture was cooled to room temperature to obtain the final high-performance cathode additive.

[0093] Based on Experiment E of Embodiment 1, the technical solution of this embodiment is tested. The difference between Experiment E and Experiment E is that the core-shell structure in this embodiment includes fine particles and coarse particles. The mass ratio of fine particle core-shell structure to coarse particle core-shell structure is 6:3 in Experiment F and 7:2 in Experiment G. The experimental results are shown in Table 3 below.

[0094] Table 3

[0095]

[0096] The γ-Al2O3 nanosheets are also electrically modulated;

[0097] γ-Al2O3 nanosheets were placed in a muffle furnace and calcined at 580±10℃ for 2 hours (heating rate 5℃ / min). After cooling, modified γ-Al2O3 nanosheets were obtained, and their isoelectric point was adjusted from pH=8.0 to pH=4.0±0.2.

[0098] The dual-size core-shell structure (fine and coarse particles) was dispersed in a buffer solution with pH=6.0; the surface Zeta potential was measured to be -30±2 mV, and the TiO2 shell was negatively charged under near-neutral conditions;

[0099] Modified γ-Al2O3 nanosheets and dual-size core-shell structures were added together to a mixer;

[0100] Add deionized water (2.5 times the total mass) and adjust the pH to 1.5 ± 0.1;

[0101] Ultrasonic dispersion was performed at 50℃ and 250 W / L power for 30 minutes (frequency 40 kHz) to allow the positively charged nanosheets and negatively charged core-shell particles to be fully electrostatically attracted.

[0102] The slurry was vacuum dried at 80℃ for 6 hours and then ground through a 300-mesh sieve to obtain an electrically matched composite.

[0103] Based on experimental group F, experiments were conducted in this embodiment as Experiment H. The difference between Experiment H and Experiment F is that in Experiment H, the γ-Al2O3 nanosheets were also electrically regulated. The experimental results are shown in Table 4 below.

[0104] Table 4

[0105]

[0106] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0107] By employing a dual-size core-shell structure in the positive electrode additive of lead-acid batteries and electrostatically pre-assembling it with γ-Al2O3 nanosheets with isoelectric point controlled, a multi-level and multi-dimensional synergy from hierarchical filling at the physical scale to strong bonding at the chemical interface is achieved, which enhances the mechanical strength, structural stability and electrochemical durability of the electrode plate, thereby significantly improving the cycle life and high and low temperature performance of the battery.

[0108] The introduction of the dual-particle-size core-shell structure works by achieving hierarchical filling and stress gradient dispersion of the multi-level pores in the lead paste. Specifically, the fine-particle core-shell structure, with its tiny size, primarily fills the nanoscale micropores in the lead paste, increasing the interfacial contact area. Through the lattice matching relationship between its titanium dioxide shell and the tetrabasic lead sulfate seed crystals, it induces the ordered growth of α-PbO2 crystals along a high-intensity orientation. The coarse-particle core-shell structure, with its larger size and thicker titanium dioxide shell, primarily fills the micrometer-scale pores and acts as a micro-skeleton during charge and discharge, effectively buffering the stress generated by the volume changes of the active material and preventing the initiation and propagation of microcracks caused by stress concentration. This structural design results in a significant reduction in the overall porosity of the electrode plate and an increase in its density. Macroscopically, this manifests as increased bending strength of the electrode plate and a reduced rate of active material shedding during cycling, thereby extending the battery's cycle life.

[0109] The isoelectric point modulation of γ-Al₂O₃ nanosheets is achieved by altering the distribution of hydroxyl groups on their surface through high-temperature calcination, thereby adjusting the isoelectric point from approximately pH 8.0 to pH 4.0 ± 0.2. This modification causes the surface zeta potential of the nanosheets to become significantly positive under strongly acidic conditions simulating battery operation. The core-shell structure, due to the properties of the titanium dioxide shell, exhibits negative charge under similar conditions. Based on this difference in charge, a strong electrostatic attraction occurs between the positively charged γ-Al₂O₃ nanosheets and the negatively charged core-shell particles when mixed in a liquid environment at a specific pH. This process achieves close proximity and pre-assembly of the two at the molecular scale, greatly increasing the effective contact interface and providing a prerequisite for the subsequent formation of strong Al-O-Ti covalent bonds, thus fundamentally enhancing the binding energy and stability of the heterojunction.

[0110] The multi-scale rough interface and high specific surface area constructed by the dual-size core-shell structure provide anchoring area and diverse bonding sites for electrical bonding, laying the physical foundation for the bonding. The electrostatic pre-assembly effect induced by isoelectric point modulation, through positioning and fixation techniques, transforms this physical foundation into chemical bonding. Their synergistic effect is that the physically hierarchical filling structure ensures the composite's superior macroscopic mechanical properties, while the strong bonding at the chemical interface ensures the composite's durability under harsh environments such as long-term electrochemical cycling, acid etching, and thermal shock, preventing the interface from becoming a weak point for failure.

[0111] The synergistic effect of these two factors is an improvement in the microstructural stability of the electrode plates. Specifically, this manifests as: enhanced interfacial bonding energy, effectively suppressing the shedding and softening of active materials during cycling; significantly improved bending strength of the electrode plates; further extended cycle life of the battery; and the formation of a more efficient heat conduction network through a dense and stable composite interface, improving the battery's high-temperature performance. This synergistic effect ultimately leads to a further improvement in the overall performance of lead-acid batteries.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An additive for positive electrodes of lead-acid batteries, characterized in that, It contains the following components by weight: Modified 4BS: 6-10 parts; Composite graphite fiber: 6-13 parts; Core-shell structure: 5-12 parts, wherein the core-shell structure includes a SiO2 core and a TiO2 shell covering it; wherein the SiO2 core has a particle size of 3.0±0.5 nm and the TiO2 shell has a thickness of 3.0±0.5 nm; γ-Al2O3 nanosheets: 0.8-1.5 parts, with a sheet diameter of 80-120 nm and a thickness of 3-5 nm; The core-shell structure is composed of fine and coarse particles; The core-shell structure includes fine particles with SiO2 core diameter of 3.0±0.5 nm and TiO2 shell thickness of 3.0±0.5 nm, as well as coarse particles with SiO2 core diameter of 10.0±1.0 nm and TiO2 shell thickness of 5.0±0.5 nm. The weight ratio of fine particles to coarse particles is (6~7):(2~3); The γ-Al2O3 nanosheets were subjected to isoelectric point regulation treatment, and their isoelectric point was pH=4.0±0.

2.

2. A method for preparing the positive electrode additive for lead-acid batteries as described in claim 1, characterized in that, Includes the following steps: Step 1: Mix the core-shell structure with γ-Al2O3 nanosheets, add deionized water for ultrasonic dispersion, dry and grind to obtain a core-shell-alumina composite; Step 2: Break the composite graphite fibers to a length of 50-100μm and mix them with modified 4BS. Add the core-shell alumina composite obtained in step 1 and continue stirring to obtain the positive electrode additive.

3. The method for preparing the positive electrode additive for lead-acid batteries as described in claim 2, characterized in that, In step 1, the conditions for ultrasonic dispersion are 40℃, 200W / L power, 40kHz frequency, and 20 minutes; The drying conditions were vacuum drying at 80℃ for 6 hours, followed by grinding through a 300-mesh sieve.

4. The method for preparing the positive electrode additive for lead-acid batteries as described in claim 3, characterized in that, In step 2, the mixing conditions with the modified 4BS are 80-120℃, 150rpm, and 60 minutes. After adding the core-shell alumina composite, the stirring conditions are 80-120℃, 100rpm, and 30 minutes.

5. The method for preparing the positive electrode additive for lead-acid batteries as described in claim 2, characterized in that, Step 1 also includes electrical regulation treatment: γ-Al2O3 nanosheets were calcined at 580±10℃ for 2 hours to adjust their isoelectric point to pH=4.0±0.2; The dual-size core-shell structure was dispersed in a pH 6.0 buffer solution, and the Zeta potential was measured to be -30 ± 2 mV. Modified γ-Al2O3 nanosheets were mixed with a dual-size core-shell structure, the pH was adjusted to 1.5±0.1, and the mixture was ultrasonically dispersed, then dried and ground.

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