Solid lead battery preparation method for constructing sulfuric acid gel solid electrolyte through in-situ polymerization gel forming

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a preparation method of a solid lead battery for constructing a sulfuric acid gel solid electrolyte through in-situ polymerization gel forming. Comprising the following steps: mixing a polymeric monomer, a cross-linking agent, a reinforcing component and a sulfuric acid carrier solution, stirring and dispersing to obtain an electrolyte precursor solution; adding the initiation system into an electrolyte precursor solution, uniformly stirring, quickly injecting into a polar plate / partition plate assembly or a to-be-formed battery cell, and standing; performing triggering treatment after infiltration, performing in-situ polymerization and crosslinking to form gel, and curing to obtain a gel solid electrolyte cell; and performing formation, capacity grading and aging treatment on the gel solid electrolyte cell to obtain the solid lead battery. Through a process path of low-viscosity precursor injection-in-situ gel forming in the battery cell-subsequent formation, full infiltration and stable immobilization of electrolyte on a pole plate pore channel and a separator fiber network are realized, so that the risks of liquid leakage and acid mist are reduced, acid layering is inhibited, and the consistency and cycle stability of the battery cell are improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and mainly relates to a method for preparing solid lead batteries by in-situ polymerization to form a sulfuric acid gel solid electrolyte. Background Technology

[0002] Lead-acid batteries, as a mature rechargeable battery system, have long held an important position in fields such as automotive start / stop systems, electric two-wheelers, backup power for communications and data centers, and industrial and commercial energy storage and emergency power supplies, thanks to their advantages such as readily available raw materials, low manufacturing costs, mature and reliable processes, well-established recycling systems, and high safety. In lead-acid battery systems, the electrolyte not only plays a crucial role in ion transport and charge balance but also directly affects the battery's internal resistance, rate performance, charge acceptance, gas evolution and water loss behavior, acid stratification, and the interfacial reaction process of the plates. Traditional flooded lead-acid batteries typically use liquid sulfuric acid electrolyte, which, while possessing high ionic conductivity and low polarization loss, is prone to problems in practical applications such as electrolyte leakage, acid mist volatilization, and increased safety hazards under transportation and vibration conditions. Furthermore, under prolonged static conditions or frequent shallow charge / discharge / deep cycle conditions, electrolyte stratification and increased local acid concentration gradients may occur, leading to uneven plate reactions, increased sulfation, and capacity decay. To reduce the risk of leakage and acid mist, and to improve vibration resistance and maintenance-free operation, valve-regulated lead-acid batteries have gradually developed into technologies such as adsorbed electrolytes and gel electrolytes. Gel electrolytes, by introducing a gelling agent to construct a three-dimensional network in a sulfuric acid system, "solidify" or "quasi-solidify" the electrolyte, which can significantly reduce fluidity, thereby reducing the risk of leakage and mitigating acid stratification.

[0003] However, existing gelation methods generally suffer from a contradiction between ion transport, mechanical strength, and manufacturability: on the one hand, to obtain sufficient retention strength and anti-delamination ability, a denser and stronger gel network is needed; however, an excessively strong gel network or a high gelling agent content will increase ion migration resistance and internal resistance, leading to a decrease in rate performance and low-temperature performance. On the other hand, gel systems are often highly sensitive to the mixing sequence, shear dispersion strength, acid concentration window, and static gelation conditions: if the viscosity is too high during the filling stage, the gel precursor cannot fully wet the electrode pores and separator fiber network, resulting in underwetting areas and discontinuous ion channels, causing increased local polarization and insufficient capacity release; if the viscosity is too low or gelation is too slow, delamination, separation, or sedimentation may occur during assembly and transportation, affecting consistency and reliability. Furthermore, gel electrolytes may also experience dehydration shrinkage, cracking, structural relaxation, or "hydration delamination" under long-term cycling and temperature fluctuations, leading to increased interfacial impedance and decreased lifetime.

[0004] For example, a gel electrolyte can be prepared using silica, sulfuric acid, and pure water as the basic system, with the addition of hydroxymethyl cellulose, anhydrous sodium sulfate and / or potassium sulfate, and alcohol additives, while simultaneously incorporating high-speed dispersion and high-pressure homogenization steps. This approach synergistically regulates the gel microstructure and electrolyte properties through thickening and inorganic salts / alcohols, but its process chain is relatively complex and requires sophisticated equipment. Furthermore, the inhibitory effect of thickeners and gel networks on ion diffusion is still difficult to completely avoid, potentially leading to more significant polarization losses at high rates and low temperatures. Another example is using sulfuric acid, fumed silica, and sodium sulfate as basic components, with the addition of organosilicon additives to reduce the impedance of the anode Pb(II) film and delay the growth of the alloy gate passivation film, thereby extending battery life. This approach is significant for improving specific failure modes, but it focuses more on the interface control of additives and does not systematically address the issues of gel distribution uniformity and gelation window control within the cell. For example, a three-dimensional gel structure with both large and small frameworks can be constructed using "nano-fumed silica + silica sol". This structure is then stored in an alkaline environment as a silica-based colloidal mother liquor, which reduces viscosity and facilitates mixing with other raw materials. This adapts to the internal formation production mode of power batteries and improves sulfuric acid stratification. While this approach enhances the design and scalable gel mixing convenience of the gel structure, it is essentially still a pre-formed silica-based network system. In the complex porous structure of the battery cell, ensuring the precursor is fully wetted within the micropores / micro-gap before forming continuous ion channels remains constrained by factors such as viscosity, penetration, and localized premature gelation, especially in thick plates, high-compaction, or high-capacity designs.

[0005] Therefore, it is necessary to develop a new electrolyte construction concept and process window for solid-state lead-acid batteries, which can achieve uniform fixation and structural stability of the electrolyte inside the cell without significantly sacrificing ion transport, while taking into account the requirements of industrial manufacturability and consistency control. Summary of the Invention

[0006] To overcome the technical problems in the prior art, this invention, without changing the ion carrier of the lead-acid system, achieves full wetting and stable fixation of the electrolyte on the electrode channels and separator fiber network through the process path of "low-viscosity precursor injection - in-situ gelation inside the cell - subsequent formation". This reduces the risk of leakage and acid mist, inhibits acid stratification, improves cell consistency and cycle stability, and avoids problems such as under-wetting, discontinuous ion channels and high internal resistance caused by traditional pre-gel / high-viscosity potting.

[0007] In this embodiment of the invention, a method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte is provided. The method includes the following steps: S1. Mix the polymer monomer, crosslinking agent, reinforcing component and sulfuric acid carrier solution, and stir to disperse to obtain an electrolyte precursor solution; S2. After adding the initiation system to the electrolyte precursor solution and stirring evenly, quickly inject it into the electrode / separator assembly or the cell to be formed, and let it stand to fully wet the electrode pores and the gaps between the separator fibers. S3. After immersion, a triggering process is performed to allow the electrolyte precursor solution to polymerize and crosslink into a gel inside the cell and mature to obtain a gel solid electrolyte cell. S4. The gel solid electrolyte cell is subjected to formation, capacity testing and aging treatment to obtain a solid lead battery.

[0008] As an optional implementation, the sulfuric acid carrier solution is an aqueous solution of sulfuric acid with a mass fraction of 20% to 40%.

[0009] As an optional implementation, the polymerizing monomer is one or more of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, or their salts; the polymerizing monomer accounts for 2% to 15% of the total mass of the electrolyte precursor solution.

[0010] As an optional implementation, the crosslinking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, or diene crosslinking agents; the crosslinking agent accounts for 0.01% to 0.3% of the total mass of the electrolyte precursor solution.

[0011] As an optional implementation, the initiation system is a thermal initiation system or a redox initiation system; the thermal initiation system is one or more of ammonium persulfate, potassium persulfate, or azo initiators, and the thermal initiator accounts for 0.05% to 0.50% of the total mass of the electrolyte precursor solution; the redox initiation system is one or more of a mixture of persulfate and sulfite, persulfate and ascorbic acid, or peroxide and reducing agent, and the redox system accounts for 0.03% to 0.30% of the total mass of the electrolyte precursor solution, wherein the oxidant mass fraction is 0.02% to 0.20% and the reducing agent mass fraction is 0.01% to 0.10%.

[0012] As an optional implementation, the reinforcing component is one or more of fumed silica, silica sol, alumina sol, and titanium dioxide sol, and the reinforcing component accounts for 0.1% to 5% of the total mass of the electrolyte precursor solution.

[0013] As an optional implementation, in step S1, the stirring and dispersion speed is 200-1200 r / min, the time is 10-120 min, and the apparent viscosity of the electrolyte precursor solution at 25°C is 10-200 mPa·s.

[0014] As an optional implementation, in step S2, the injection method includes one or more of atmospheric pressure injection, negative pressure assisted injection, or pulse injection; after injection, the injection is allowed to stand for 2 to 30 minutes.

[0015] As an optional implementation, the triggering process is either heat-triggered or redox-triggered. During the heat-triggered process, the gelation temperature is 20~70℃ and the gelation time is 5~180min. During the redox-triggered process, the gelation time is 10~120min at room temperature.

[0016] As an optional implementation, in step S3, the curing temperature is 20~60℃ and the curing time is 0.5~12h.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention achieves stable retention and uniform distribution of sulfuric acid electrolyte inside the battery cell through a synergistic process of "precursor preparation - low viscosity injection - in-situ polymerization into gel within the battery cell - formation". During the injection stage, the electrolyte precursor maintains a low viscosity, which can fully enter the multi-level channels of the electrode plate and the fiber network of the separator, and complete the full wetting of the pores and interfaces. Subsequently, in-situ polymerization and cross-linking are carried out inside the battery cell to form a three-dimensional gel skeleton, which fixes the sulfate ion carrier in the gel network. Thus, without relying on a high proportion of inorganic thickeners, the electrolyte is effectively retained, which significantly reduces the safety risks of leakage, acid mist and transportation vibration.

[0018] (2) This invention, through windowed design of the monomer / crosslinking agent / initiator system and gelation conditions, enables the gelation process to be controllable, predictable, and uniform within the battery cell. Under set temperature or redox initiation conditions, the precursor can complete polymerization and crosslinking within a limited time, avoiding premature local curing, channel closure, and structural inhomogeneity caused by excessively rapid gelation; at the same time, it avoids liquid precipitation, sedimentation, and local acid stratification caused by excessively slow gelation. Compared with traditional systems that rely solely on SiO2 physical gel or a single thickener, the polymer crosslinking network formed by this invention has better structural stability and shrinkage resistance, and can maintain relatively stable ion channels and electrolyte retention capacity under cycling and temperature fluctuation conditions, thereby delaying the growth of interfacial impedance and improving cycling stability.

[0019] (3) In the in-situ gelation process within the cell of the present invention, the gel network is simultaneously constructed in the electrode channels and the gaps between the separator fibers, so that the electrolyte is "immobilized within the channels", thereby inhibiting electrolyte convection and macroscopic migration, significantly reducing acid stratification and the resulting uneven local reaction. After gel fixation, a more continuous ion transport path and a more stable interface wetting state are formed inside the cell, which is beneficial to improving the utilization rate of active materials and reducing polarization. Compared with simply increasing the gelling agent content to obtain fixation strength, the present invention maintains as low a transmission resistance as possible while improving fixation, taking into account rate performance and low temperature working stability, and improving the charging acceptance and discharge output consistency.

[0020] (4) The process of this invention uses a sulfuric acid system as an ion carrier and employs industrially available monomers, crosslinking agents, and reinforcing components. The overall process consists of "preparation, injection, triggering gelation, and formation," with clear process steps, strong equipment versatility, and ease of large-scale scaling. This invention avoids high-cost routes such as complex pre-prepared gel membranes or porous carrier acid absorption, and reduces dependence on high-pressure injection and complex wetting equipment through the injection of low-viscosity precursors. The gelation triggering conditions can be flexibly controlled by temperature or redox system, making it easy to be compatible with the modification of existing lead-acid battery production lines. Therefore, this invention reduces the risk of leakage and acid mist, improves cell consistency and lifespan stability, and has good prospects for continuous production and industrial application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The actual test voltage-capacity curves of the battery prepared in this invention are shown; (a) is the charging curve, and (b) is the discharging curve. Detailed Implementation

[0023] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0024] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0026] The battery cells used in the following examples and comparative examples are valve-regulated lead-acid (VRLA) battery cells of the same specification, with identical plate system, separator system, and shell structure. The differences between the examples and comparative examples lie only in the composition of the electrolyte precursor, the in-situ gelation triggering method, and its conditions. In this specification, "solid-state lead-acid battery" refers to a quasi-solid-state lead-acid battery in which the electrolyte inside the cell undergoes in-situ polymerization and cross-linking to form a gel network, thereby achieving electrolyte fixation. The apparent viscosity of the electrolyte precursor was measured using a rotational viscometer at 25°C; the gelation time was determined by the criterion of "the electrolyte precursor losing its fluidity and forming a stable gel."

[0027] To address the common problems in existing solid-state lead-acid battery electrolyte technologies, such as uneven wetting and microscale acid concentration gradient-induced local polarization and lifetime dispersion, as well as dehydration shrinkage, structural relaxation, or cracking under long-term cycling and temperature fluctuations, this invention proposes a method for preparing solid-state lead-acid batteries by in-situ polymerization to form a sulfuric acid gel solid electrolyte, as shown below: Raw material selection: Polymer system: The polymer monomer is one or more of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid or its salts; the crosslinking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate or diene crosslinking agent; the initiation system is a thermal initiation system or a redox initiation system; wherein the thermal initiation system is one or more of ammonium persulfate, potassium persulfate or azo initiator; wherein the redox initiation system is one or more of persulfate and sulfite, persulfate and ascorbic acid or peroxide and reducing agent compound system, the selection of the above initiation system is used to control the gelation rate and improve the gelation uniformity; the reinforcing component is one or more of fumed silica, silica sol, alumina sol or titanium dioxide sol.

[0028] Step S1: Prepare a sulfuric acid carrier solution with a mass fraction of 20%–40%. Weigh the materials according to the following mass fractions: 2%–15% monomer, 0.01%–0.3% crosslinking agent, and 0.1%–5% reinforcing component. Mix the monomer, crosslinking agent, reinforcing component, and sulfuric acid carrier solution, and stir at 200–1200 r / min for 10–120 min (ultrasonic dispersion or shear dispersion can be used if necessary to improve the dispersion uniformity of the inorganic reinforcing component and avoid uneven gelation caused by local agglomeration). Obtain an electrolyte precursor solution with an apparent viscosity of 10–200 mPa·s at 25°C. This viscosity of the electrolyte precursor solution ensures both fluidity and wettability, and allows for rapid in-situ gelation under subsequent triggering conditions. Mixing the above raw materials and proportions achieves a balance between gel strength and ion transport, improving the mechanical stability, shrinkage resistance, and electrolyte retention capacity of the gel network.

[0029] Step S2: After adding the initiation system to the electrolyte precursor solution and stirring evenly, quickly inject it into the electrode / separator assembly or the cell to be formed by means of atmospheric pressure injection, negative pressure assisted injection or pulse injection, and let it stand for 2 to 30 minutes to fully wet the electrode pores and the gaps between the separator fibers, remove entrained air bubbles and promote the precursor to enter the microporous region.

[0030] S3. After impregnation, triggering treatment is performed. Depending on the initiation system, the corresponding triggering method is selected: heating triggering or redox triggering. When heating triggering is used, the gelation temperature is 20–70℃, and the gelation time is 5–180 min. When redox triggering is used, the gelation time is 10–120 min at room temperature to ensure uniform in-situ gelation within the cell. After in-situ gelation, a curing treatment at 20–60℃ is performed for 0.5–12 h to improve the structural stability of the gel network and reduce structural fluctuations during subsequent formation processes, thus obtaining a gel solid electrolyte cell.

[0031] S4. The gel solid electrolyte cell is subjected to formation, capacity testing, and aging treatment to obtain a solid lead-acid battery. Formation and capacity testing are carried out according to a conventional valve-controlled process, with the following specific conditions: After in-situ gelation of the cell, it is formed at 25±2℃: constant current charging at 0.10C to 14.7V, then constant voltage at 14.7V until the current decays to 0.02C (typically 12-16 hours); then open-circuit resting for 1-2 hours for equalization, then resting at 25±2℃ for 12 hours, followed by discharge at 0.2C to 10.5V for capacity testing, then constant current charging at 0.10C to 14.4V and constant voltage at 14.4V until 0.02C (cutoff) for recharging; finally, open-circuit aging at 25±2℃ for 48 hours.

[0032] The following is a further explanation using specific embodiments.

[0033] Example 1 A method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte includes the following steps: Take 400 mL of a 30% (w / w) sulfuric acid carrier solution, add 24 g of acrylamide and 12 g of 2-acrylamido-2-methylpropanesulfonic acid, and stir until completely dissolved; add 0.10 g of N,N′-methylenebisacrylamide as a crosslinking agent; add 4.0 g of fumed silica as a reinforcing component, stir at 600 r / min for 40 min at 25 °C, and ultrasonically disperse for 10 min to obtain a homogeneous electrolyte precursor solution. The apparent viscosity of this precursor at 25 °C was measured to be approximately 80 mPa·s.

[0034] Add 0.60 g of ammonium persulfate to the above precursor solution as a thermal initiator, stir rapidly for 2 min to mix well, and then immediately inject into the electrode / separator assembly to ensure that the precursor completely wets the electrode pores and the gaps between the separator fibers; after injection, let stand for 10 min to remove entrained air bubbles.

[0035] The injected battery cells were placed in a constant temperature environment of 45℃ for 60 min to carry out in-situ polymerization and cross-linking into a gel; after the gel was formed, it was cured at 30℃ for 2 h.

[0036] After the cells are gelled in situ, they are formed at 25±2℃: constant current charging at 0.10C to 14.7V, then constant voltage charging at 14.7V until the current decays to 0.02C and is cut off, typically 12-16 hours; then open circuit resting for 1-2 hours for equalization, then resting at 25±2℃ for 12 hours, then discharging at 0.2C to 10.5V for capacity testing, then constant current charging at 0.10C to 14.4V and constant voltage charging at 14.4V until 0.02C and then recharging; finally, open circuit aging at 25±2℃ for 48 hours to obtain solid lead-acid batteries.

[0037] Example 2 A method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte includes the following steps: Take 400 mL of a 30% (w / w) sulfuric acid carrier solution, add 18 g of acrylamide and 18 g of 2-acrylamido-2-methylpropanesulfonic acid, and stir until completely dissolved; add 0.10 g of N,N′-methylenebisacrylamide as a crosslinking agent; add 4.0 g of fumed silica as a reinforcing component, stir at 600 r / min for 40 min at 25 °C, and ultrasonically disperse for 10 min to obtain a homogeneous electrolyte precursor solution. The apparent viscosity of this precursor at 25 °C was measured to be approximately 120 mPa·s.

[0038] Add 0.60 g of ammonium persulfate to the above precursor solution as a thermal initiator, stir rapidly for 2 min to mix well, and then immediately inject into the electrode / separator assembly to ensure that the precursor completely wets the electrode pores and the gaps between the separator fibers; after injection, let stand for 10 min to remove entrained air bubbles.

[0039] The injected battery cells were placed in a constant temperature environment of 45℃ for 60 min to carry out in-situ polymerization and cross-linking into a gel; after the gel was formed, it was cured at 30℃ for 2 h.

[0040] After the cells are gelled in situ, they are formed at 25±2℃: constant current charging at 0.10C to 14.7V, then constant voltage charging at 14.7V until the current decays to 0.02C and is cut off, typically 12-16 hours; then open circuit resting for 1-2 hours for equalization, then resting at 25±2℃ for 12 hours, then discharging at 0.2C to 10.5V for capacity testing, then constant current charging at 0.10C to 14.4V and constant voltage charging at 14.4V until 0.02C and then recharging; finally, open circuit aging at 25±2℃ for 48 hours to obtain solid lead-acid batteries.

[0041] Example 3 A method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte includes the following steps: Take 400 mL of a 30% (w / w) sulfuric acid carrier solution, add 24 g of acrylamide and 12 g of 2-acrylamido-2-methylpropanesulfonic acid, and stir until completely dissolved; add 0.10 g of N,N′-methylenebisacrylamide as a crosslinking agent; add 4.0 g of fumed silica as a reinforcing component, stir at 500 r / min for 40 min at 25 °C, and ultrasonically disperse for 10 min to obtain a homogeneous electrolyte precursor solution. The apparent viscosity of this precursor at 25 °C is measured to be approximately 80 mPa·s.

[0042] Add 0.60 g of ammonium persulfate to the above precursor solution as a thermal initiator, stir rapidly for 2 min to mix well, and then immediately inject into the electrode / separator assembly to ensure that the precursor completely wets the electrode pores and the gaps between the separator fibers; after injection, let stand for 10 min to remove entrained air bubbles.

[0043] The injected battery cells were placed in a constant temperature environment of 45℃ for 60 min to carry out in-situ polymerization and cross-linking into a gel; after the gel was formed, it was cured at 30℃ for 2 h.

[0044] After the cells are gelled in situ, they are formed at 25±2℃: constant current charging at 0.10C to 14.7V, then constant voltage charging at 14.7V until the current decays to 0.02C and is cut off, typically 12-16 hours; then open circuit resting for 1-2 hours for equalization, then resting at 25±2℃ for 12 hours, then discharging at 0.2C to 10.5V for capacity testing, then constant current charging at 0.10C to 14.4V and constant voltage charging at 14.4V until 0.02C and then recharging; finally, open circuit aging at 25±2℃ for 48 hours to obtain solid lead-acid batteries.

[0045] Comparative Example 1 Compared with Example 1, Comparative Example 1 did not use in-situ polymerization crosslinking to form a gel. Instead, it used liquid sulfuric acid electrolyte with the same mass fraction of sulfuric acid (30%) directly injected into the battery cell. All other assembly and formation conditions were the same as in Example 1.

[0046] Comparative Example 2 Compared with Example 1, Comparative Example 2 used a traditional physical gel thickening method without in-situ polymerization and cross-linking. Specifically, 400 mL of sulfuric acid electrolyte with a sulfuric acid mass fraction of 30% was taken, and 8.0 g of fumed SiO2 was added. The electrolyte was dispersed at high speed at 25°C for 30 min to obtain a high-viscosity physical gel electrolyte. Subsequently, the gel electrolyte was directly injected into the battery cell, and the remaining assembly and formation conditions were the same as in Example 1.

[0047] Testing and Characterization Electrochemical performance testing includes indicators such as capacity, initial discharge efficiency, rate discharge performance, and AC internal resistance. AC internal resistance is measured at 1 kHz. Specifically, the AC internal resistance is measured using an internal resistance meter / impedance meter at 1 kHz four-wire method under conditions of 25±2℃ and 2 hours of full charge followed by resting, and the average of three measurements is taken. The 0.2C initial discharge capacity is the capacity obtained by constant current discharge at 0.2C to 10.5V at 25±2℃ (Q=I×t). The initial efficiency is calculated as "discharge capacity / charge input capacity × 100%" for the same cycle. The charge input capacity is accumulated during the charging process (0.10C to 14.4–14.7V, constant voltage to 0.02C cutoff). The 1C discharge capacity is the capacity obtained by full charge followed by resting for 2 hours. The voltage was obtained by discharging at 1C to 10.5V at 25±2℃ after h; the 80% DOD cycle life was obtained by cycling at 25±2℃ with the following steps: discharge at 0.5C to 0.8Q0 (or to 10.5V whichever comes first), charge at 0.2C to 14.4V and hold at 0.05C until the cutoff voltage is reached. A 0.2C retest was performed every 50 cycles, and the number of cycles when the capacity dropped to 0.8Q0 was recorded as the lifespan. Specific results are shown in Table 1 and... Figure 1 As shown (the actual test voltage-capacity curve of the battery obtained in Example 1).

[0048] Table 1 Electrical performance of solid lead-acid batteries As shown in Table 1, Example 1 exhibits superior performance compared to the comparative example, with an AC internal resistance of 23.6 mΩ, a first discharge capacity of 7.10 Ah at 0.2C, a first efficiency of 93.2%, a discharge capacity of 6.05 Ah at 1C, and a cycle life of 337 cycles at 80% DOD. This demonstrates that the process route of the present invention, "low-viscosity precursor injection - in-situ polymerization into gel within the cell - formation," can construct continuous and stable gel ion channels within the cell and effectively retain sulfuric acid electrolyte, while ensuring sufficient wetting of the electrode pores and separator fiber network by the electrolyte. This significantly reduces ohmic internal resistance and polarization caused by under-wetting, discontinuous ion channels, or electrolyte migration / acid stratification, improves the utilization rate of active materials, and ultimately results in higher usable capacity, higher first efficiency, and better rate output. Furthermore, it suppresses impedance growth and performance degradation during cycling, significantly improving cycle life.

[0049] The accompanying figure shows the voltage-capacity (VQ) curve of the battery cell in Example 1. The charge-discharge curve is continuous and smooth, with a clear plateau range, and the capacity at the end of the discharge is consistent with the 0.2C capacity (approximately 7.10 Ah) in Table 1, indicating that the capacity is fully released and the polarization is small under the specified voltage window. At the same time, the curve does not show any abnormal drops or distortions during the charge-discharge process, which confirms that the electrolyte distribution is uniform and the ion transport path is stable after in-situ gelation, which is beneficial to reducing voltage loss and improving rate capability and cycle stability.

[0050] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. However, it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte, characterized in that, The method includes the following steps: S1. Mix the polymer monomer, crosslinking agent, reinforcing component and sulfuric acid carrier solution, and stir to disperse to obtain an electrolyte precursor solution; S2. After adding the initiation system to the electrolyte precursor solution and stirring evenly, quickly inject it into the electrode / separator assembly or the cell to be formed, and let it stand to fully wet the electrode pores and the gaps between the separator fibers. S3. After immersion, a triggering process is performed to allow the electrolyte precursor solution to polymerize and crosslink into a gel inside the cell and mature to obtain a gel solid electrolyte cell. S4. The gel solid electrolyte cell is subjected to formation, capacity testing and aging treatment to obtain a solid lead battery.

2. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The sulfuric acid carrier solution is an aqueous solution of sulfuric acid with a mass fraction of 20% to 40%.

3. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The polymeric monomer is one or more of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, or their salts; the polymeric monomer accounts for 2% to 15% of the total mass of the electrolyte precursor solution.

4. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The crosslinking agent is one or more of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, or diene crosslinking agents; the crosslinking agent accounts for 0.01% to 0.3% of the total mass of the electrolyte precursor solution.

5. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The initiation system is a thermal initiation system or a redox initiation system; The thermal initiation system is one or more of ammonium persulfate, potassium persulfate, or azo initiators, and the thermal initiator accounts for 0.05% to 0.50% of the total mass of the electrolyte precursor solution. The redox initiation system is one or more of the following: persulfate and sulfite, persulfate and ascorbic acid, or peroxide and reducing agent complex system. The redox system accounts for 0.03% to 0.30% of the total mass of the electrolyte precursor solution.

6. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The reinforcing component is one or more of fumed silica, silica sol, alumina sol, and titanium dioxide sol, and the reinforcing component accounts for 0.1% to 5% of the total mass of the electrolyte precursor solution.

7. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, In step S1, the stirring and dispersion speed is 200-1200 r / min, the time is 10-120 min, and the apparent viscosity of the electrolyte precursor solution at 25°C is 10-200 mPa·s.

8. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, In step S2, the injection method includes one or more of atmospheric pressure injection, negative pressure assisted injection, or pulse injection; after injection, the injection is allowed to stand for 2 to 30 minutes.

9. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, The triggering process is either heat-triggered or oxidation-reduction-triggered. During the heat-triggered process, the gelation temperature is 20~70℃ and the gelation time is 5~180min. During the oxidation-reduction-triggered process, the gelation time is 10~120min at room temperature.

10. The method for preparing a solid lead battery using an in-situ polymerized gel to construct a sulfuric acid gel solid electrolyte according to claim 1, characterized in that, In step S3, the curing temperature is 20~60℃ and the curing time is 0.5~12h.

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