A method for preparing a positive electrode sheet of a lead-carbon battery by a dry process, the positive electrode sheet, and a battery

Abstract

The application belongs to the technical field of lead-carbon batteries, and specifically provides a method for preparing a positive plate of a lead-carbon battery by a dry method, the positive plate and the battery. The method comprises the following steps: uniformly mixing material containing lead powder and polytetrafluoroethylene to obtain dry powder; applying the dry powder to both sides of a metal grid, pressing the dry powder, and then immersing the pressed dry powder in an acid solution, and then taking out the pressed dry powder, flattening the pressed dry powder, and solidifying the flattened pressed dry powder. The positive plate prepared by the method can not only improve the stability and consistency of the battery, but also reduce the production energy consumption, provides an experimental basis for breaking through the bottleneck of uniformity of active material in the traditional paste coating process, promotes the industrial application development of the technology in energy storage, and opens up a new idea for the sustainable development of the lead-carbon battery manufacturing industry.

Description

Technical Field

[0001] This invention relates to the field of lead-carbon battery technology, and in particular to a method for dry preparation of a lead-carbon battery positive electrode sheet, the positive electrode sheet, and the battery. Background Technology

[0002] In large-scale industrial production, lead-carbon battery plates are generally produced using a wet coating method. The specific process is as follows: Lead powder and additives are mixed evenly in a paste mixer, then deionized water is added and stirred until the mixture reaches the appropriate consistency. Sulfuric acid solution is then slowly added dropwise and stirred thoroughly. The apparent density of the lead paste is controlled, and the paste is evenly coated onto the lead alloy grid. The coated green plates are then evenly pressed flat with rollers, impregnated with acid, and placed in a curing chamber for drying and curing.

[0003] Although this method can control the apparent density of lead paste, its core drawback lies in its inability to precisely control the uniformity of the positive electrode active material on the plate. In addition, the addition of sulfuric acid can easily cause local agglomeration of PbSO4, thus affecting the production consistency of the electrode plate. Moreover, the addition of adhesive positive electrode binders can lead to difficulties in paste application and poor ductility, limiting the improvement of positive electrode performance. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in the prior art. Therefore, one object of this invention is to provide a method for dry preparation of a lead-carbon battery positive electrode sheet, the positive electrode sheet, and the battery.

[0005] In a first aspect, the present invention provides a method for dry preparation of a positive electrode sheet for a lead-carbon battery, comprising:

[0006] The materials containing lead powder and polytetrafluoroethylene are mixed evenly to obtain a dry powder;

[0007] The dry powder is applied to both sides of the metal grid, pressed under pressure, then immersed in an acid solution, and then removed, flattened, and cured.

[0008] According to the preparation method provided by this invention, a dry process combined with polytetrafluoroethylene (PTFE) binder effectively controls the arrangement and internal pores of the active materials. This results in a more uniform arrangement of the positive electrode active material particles and a doubling of the specific surface area of ​​the positive electrode active material. Simultaneously, the positive electrode sheet constructs a mesoporous system, which is beneficial for improving electrolyte permeability, thus creating a positive electrode system with high specific surface area, multiple active sites, and long cycle life. Furthermore, the introduction of PTFE enhances the interaction forces between the active materials, reduces the dispersion and shedding of the positive electrode lead paste, and strengthens the bonding force between the active materials. Specifically, the positive electrode sheet prepared after introducing PTFE can significantly increase the cycle life of lead-carbon batteries by 79%, and the discharge capacity can also increase by 27%-45% at different rates. The positive electrode sheet prepared using the method of this invention not only improves the stability and consistency of battery manufacturing but also reduces production energy consumption. It provides an experimental basis for overcoming the bottleneck of traditional paste-coating processes that limit the uniformity of active materials, promotes the industrial application of this technology in energy storage, and opens up new avenues for the sustainable development of the lead-carbon battery manufacturing industry.

[0009] In some embodiments of the present invention, the mass ratio of lead powder to polytetrafluoroethylene is 100:(5-15). For example, 100:5, 100:7, 100:10, 100:12, 100:15, etc., or any range between any two of the above values. The inventors have found that controlling the mass ratio of lead powder to polytetrafluoroethylene within the above range can improve battery cycle life and increase battery discharge specific capacity.

[0010] In some embodiments of the present invention, the pressure applied for compaction is 0.6 MPa-0.8 MPa, and the time is 8 min-12 min. Controlling the pressure and time within the above range can stabilize the internal structure of the positive electrode, effectively improve the stability of the battery during charge-discharge cycles, reduce battery capacity decay and internal resistance increases caused by electrode plate problems, thereby extending the overall service life of the battery and providing solid support for the battery's reliable performance.

[0011] In some embodiments of the present invention, the cured positive electrode sheet is dropped three times from a height of 1 meter. By measuring the weight loss of the sheet before and after the drops, the optimal pressure and time conditions are determined. During the manufacturing process of the positive electrode sheet, drop tests are used to determine the appropriate pressure and time for preparation. The degree of breakage of the electrode sheet before and after the drop test can directly reflect the quality of the electrode sheet. If an electrode sheet shows a low degree of breakage after the drop test, it indicates that the sheet structure is stable and has good mechanical strength and toughness.

[0012] In some embodiments of the present invention, the acid solution is selected from sulfuric acid solution. Immersion in sulfuric acid can form an etching layer on the surface of the positive electrode, achieving the purpose of interweaving basic lead sulfate crystals to form the skeleton structure of the electrode plate and enhancing the mechanical strength of the electrode plate.

[0013] In some embodiments of the present invention, the metal grid is selected from lead alloy grids.

[0014] In some embodiments of the present invention, the concentration of the acid solution is 1.0 g·L⁻¹. -1 -1.2g·L -1 .

[0015] In some embodiments of the present invention, the soaking time is 8 min to 12 min.

[0016] In some embodiments of the present invention, after being soaked in sulfuric acid, the sample is flattened and uniformly pressed with a roller, and then placed in a curing chamber for curing.

[0017] In some embodiments of the present invention, the curing process is shown in Table 1.

[0018] Table 1

[0019]

[0020] In some embodiments of the present invention, the material further includes one or more of red lead, activated carbon, polypropylene fiber, and carbon fiber.

[0021] In some embodiments of the present invention, the mass ratio of the lead powder, the red lead, the activated carbon, the polypropylene fiber, and the carbon fiber is 100:(1-3):(0.3-0.5):(0.1-0.3):(0.1-0.3).

[0022] In a second aspect, this invention provides a positive electrode sheet for a lead-carbon battery, which is prepared using the method described above. This positive electrode sheet exhibits a stable plate structure, good mechanical strength and toughness, and the positive electrode active material has a high specific surface area, good bonding between materials, good electrolyte permeability, and high electron transport efficiency, resulting in excellent electrical performance and a long service life.

[0023] In some embodiments of the present invention, the specific surface area of ​​the positive electrode active material of the lead-carbon battery positive electrode sheet is 5m². 3 ·g -1 -6m 3 ·g -1 It should be noted that the above-mentioned positive electrode active material refers to a mixed positive electrode active material of lead dioxide and polytetrafluoroethylene, or a mixed positive electrode active material of lead dioxide, polytetrafluoroethylene and other additives (red lead, activated carbon, polypropylene fiber, carbon fiber, etc.).

[0024] In some embodiments of the present invention, the pore volume of the positive electrode sheet of the lead-carbon battery is 0.002 cm³. 3 ·g -1 -0.006cm 3 ·g -1 The positive electrode of the present invention has a large pore volume, which provides space for the electrolyte, ensuring that the entire positive electrode is fully wetted during charging and discharging, and also provides space for the positive electrode active material to mitigate volume changes.

[0025] In some embodiments of the present invention, the pore size of the positive electrode sheet of the lead-carbon battery is 2nm-50nm. The pore size of the positive electrode sheet of the present invention is between 2nm and 50nm, which falls within the range of mesoporous structures, providing a rapid transport migration channel for electrolyte and ions, and ensuring the timeliness of ion transport during high-rate discharge of the battery.

[0026] In a third aspect, the present invention provides a lead-carbon battery comprising the aforementioned positive electrode. This lead-carbon battery exhibits excellent rate performance and cycle stability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a process demonstration diagram of the dry preparation of the positive electrode sheet in Embodiment 1 of the present invention;

[0029] Figure 2 This is a SEM image of the positive electrode sheet prepared in Comparative Example 1 of this invention;

[0030] Figure 3 This is a SEM image of the positive electrode sheet prepared in Example 1 of this invention;

[0031] Figure 4 This is the N2 adsorption-desorption isotherm and pore size distribution diagram of the positive electrode sheet prepared in Comparative Example 1 of this invention.

[0032] Figure 5 This is the N2 adsorption-desorption isotherm and pore size distribution diagram of the positive electrode sheet prepared in Example 1 of this invention;

[0033] Figure 6 These are graphs showing the battery cycle performance test results of Embodiment 1 and Comparative Example 1 of the present invention;

[0034] Figure 7 These are graphs showing the battery cycle performance test results of Examples 1-3 of this invention;

[0035] Figure 8 The graph shows the battery cycle performance test results of Embodiment 1 and Comparative Examples 2-3 of this invention. Detailed Implementation

[0036] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.

[0037] Example 1

[0038] (1) This embodiment provides a positive electrode sheet, and the specific preparation process is as follows:

[0039] 100g lead powder, 5g polytetrafluoroethylene, 2g red lead, 0.4g activated carbon, 0.15g polypropylene fiber, and 0.2g carbon fiber were placed in a high-speed mixer and stirred at 800r / min for 10 minutes until dry-mixed. 23g of the dry mixture and a lead alloy grid were then placed in a stainless steel mold and pressed under a pressure of 0.6MPa for 10 minutes. The mixture was then soaked in sulfuric acid with a density of 1.10g / L for 10 minutes, flattened evenly with a roller, and cured in a curing chamber. The above-described dry method for preparing the positive electrode sheet is briefly described below. Figure 1 As shown.

[0040] (2) This embodiment provides a lead-carbon battery, and the specific process is as follows:

[0041] The positive and negative electrode plates are matched and assembled into a lead-carbon battery. After acidification, the residual acid is removed, a safety valve is installed, and the battery is assembled into a valve-regulated lead-carbon battery.

[0042] Example 2

[0043] (1) This embodiment provides a positive electrode sheet, and the specific preparation process is as follows:

[0044] 100g of lead powder, 10g of polytetrafluoroethylene, 2g of red lead, 0.4g of activated carbon, 0.15g of polypropylene fiber and 0.2g of carbon fiber were placed in a high-speed mixer and stirred at 800r / min for 10min until dry and uniform. Then, 23g of the dry material and lead alloy grid were placed in a stainless steel mold and pressed under a pressure of 0.6MPa for 10min. Then, the mixture was soaked in sulfuric acid with a density of 1.10g / L for 10 minutes, and then flattened evenly with a roller and placed in a curing chamber for curing.

[0045] (2) The preparation process of lead-carbon battery is the same as that in Example 1.

[0046] Example 3

[0047] (1) This embodiment provides a positive electrode sheet, and the specific preparation process is as follows:

[0048] 100g of lead powder, 15g of polytetrafluoroethylene, 2g of red lead, 0.4g of activated carbon, 0.15g of polypropylene fiber and 0.2g of carbon fiber were placed in a high-speed mixer and stirred at 800r / min for 10min until dry and uniform. Then, 23g of the dry material and lead alloy grid were placed in a stainless steel mold and pressed under a pressure of 0.6MPa for 10min. Then, the mixture was soaked in sulfuric acid with a density of 1.10g / L for 10 minutes, and then flattened evenly with a roller and placed in a curing chamber for curing.

[0049] (2) The preparation process of lead-carbon battery is the same as that in Example 1.

[0050] Comparative Example 1

[0051] (1) This comparative example provides a positive electrode sheet, and the specific preparation process is as follows:

[0052] 100g of lead powder, 2g of red lead, 0.4g of activated carbon, 0.15g of polypropylene fiber, and 0.2g of carbon fiber were placed in a paste mixer and stirred for 10 minutes until dry and uniform. Then, 10g of deionized water was added and stirred for another 10 minutes until the paste reached a suitable consistency. Finally, 8.70g of a sulfuric acid solution with a density of 1.40g / L was slowly added dropwise and stirred thoroughly. The apparent density of the lead paste was controlled at 4.3±0.05g / cm³. 3 Apply lead paste evenly to a surface measuring 69.00×44.30×2.00mm. 3 The coating mass on the lead alloy grid is 28±0.01g. After coating, the green electrode plate is evenly flattened with a roller, then immersed in sulfuric acid with a density of 1.10g / L for 3s, and then placed in a curing chamber.

[0053] (2) The preparation process of lead-carbon battery is the same as that in Example 1.

[0054] Comparative Example 2

[0055] (1) This comparative example provides a positive electrode sheet, and the specific preparation process is as follows:

[0056] 100g of lead powder, 5g of polyacrylic acid (PAA), 2g of red lead, 0.4g of activated carbon, 0.15g of polypropylene fiber and 0.2g of carbon fiber were placed in a high-speed mixer and stirred at 800r / min for 10min until dry and uniform. 23g of the dry material and lead alloy grid were placed in a stainless steel mold and pressed under a pressure of 0.6MPa for 10min. Then, the mixture was soaked in sulfuric acid with a density of 1.10g / L for 10 minutes, flattened evenly with a roller, and placed in a curing chamber for curing.

[0057] (2) The preparation process of lead-carbon battery is the same as that in Example 1.

[0058] Comparative Example 3

[0059] (1) This comparative example provides a positive electrode sheet, and the specific preparation process is as follows:

[0060] 100g lead powder, 5g polyvinyl alcohol (PVA), 2g red lead, 0.4g activated carbon, 0.15g polypropylene fiber and 0.2g carbon fiber were placed in a high-speed mixer and stirred at 800r / min for 10min until dry and uniform. 23g of the dry material and lead alloy grid were placed in a stainless steel mold and pressed under a pressure of 0.6MPa for 10min. Then, the mixture was soaked in sulfuric acid with a density of 1.10g / L for 10 minutes, flattened evenly with a roller, and placed in a curing chamber for curing.

[0061] (2) The preparation process of lead-carbon battery is the same as that in Example 1.

[0062] SEM image of the positive electrode prepared in Comparative Example 1 is shown below. Figure 2 As shown, the SEM image of the positive electrode sheet prepared in Example 1 is as follows. Figure 3 As shown, it clearly reveals the microscopic morphological characteristics of the battery's positive electrode plate. (Comparison) Figure 2 and Figure 3 In Example 1, the active material particles of the positive electrode sheet are more densely packed. This is because the dry process does not produce cracks due to water evaporation, resulting in a tighter connection between the particles. This structure forms a continuous conductive network, which not only facilitates electron transport but also reduces the internal resistance of the battery.

[0063] To systematically study the effect of dry and wet processes on the microstructure of positive electrode active materials, N2 adsorption-desorption experiments were used to investigate the specific surface area and pore size distribution of two samples. The positive electrode active material powder was placed in a vacuum degassing station and continuously degassed at 393 K for 8 hours to ensure complete removal of surface adsorbed substances. Then, N2 adsorption-desorption isotherms were recorded at a low temperature of 77 K. The specific surface area was calculated based on the BET model, and the pore size distribution was analyzed using the BJH algorithm. Detailed analysis and calculation results are shown below. Figure 4-5 And Table 2.

[0064] Table 2

[0065]

[0066] The measurement results show that the specific surface area of ​​the positive electrode active material in Example 1 reached 5.341 m². 3 ·g -1 Compared to the 2.703m of the positive electrode sheet in Comparative Example 1 using the traditional wet process, 3 ·g -1The specific surface area was nearly doubled. This means more active sites are available for electrochemical reactions, which directly contributes to increased battery capacity. Furthermore, the pore volume of the positive electrode in Example 1 is concentrated in the range of 0.002-0.006 cm³. 3 ·g -1 It is significantly larger than 0.0005-0.0018 cm in Comparative Example 1. 3 ·g -1 This also provides space for the electrolyte, ensuring that the entire positive electrode sheet is fully wetted during charging and discharging, and also provides space for the positive electrode active material to mitigate volume changes. The pore size in the positive electrode sheet of Example 1 is between 2-50 nm, which falls within the mesoporous range, providing a rapid transport migration channel for the electrolyte and ions, ensuring the timely transport of ions during high-rate discharge.

[0067] The battery cycle performance of the examples and comparative examples was measured. See the detailed results below. Figure 6-8 .

[0068] A comparative experiment was conducted on the batteries under a long-term cycle test at 0.5C with 100% DOD, and the cycle stability performance of the batteries was as follows: Figure 6 As shown, the battery life of Comparative Example 1 was only 124 cycles, and its discharge capacity was low. The battery life of Example 1 was extended to 222 cycles. This demonstrates that the battery prepared using the method of the present invention has a much higher capacity than conventional batteries, which can greatly improve the discharge capacity of lead-carbon batteries. When a polytetrafluoroethylene binder plate is used as the positive electrode, the cycle stability of the battery is greatly improved.

[0069] from Figure 7 It is known that the optimal amount of PTFE is 5 wt%, resulting in a longer battery life and stable discharge coulombic efficiency. However, when PTFE is added at a concentration of 10 wt%, the cycle count drops to 164. Subsequently, when the PTFE concentration is increased to 15 wt%, the cycle count further decreases to 106. This trend indicates that excessive PTFE may impair the cycle stability of the system. Too much PTFE clogs the pore structure, hindering the transport of electrons and electrolytes, leading to a sharp decline in battery discharge capacity and unstable coulombic efficiency. Adding an appropriate amount of PTFE can not only improve the battery's discharge capacity but also stabilize the battery's internal structure, ensuring a delay in battery degradation.

[0070] from Figure 8It can be seen that, comparing the cycling performance differences between PTFE and other polymer binders such as polyvinyl alcohol (PVA) and polyacrylic acid (PAA), PTFE-based electrodes exhibit significant advantages in the 100% DOD cycle test. Firstly, due to the higher chemical inertness of PTFE's fluorocarbon chain structure, it can maintain the mechanical stability of the interface between the active material and the current collector, extending the battery's lifespan. Secondly, PTFE has better acid resistance compared to other polymer binders. Other binders undergo structural damage and hydrolysis in the concentrated acid environment inside lead-carbon batteries, causing polymer chain breakage and weakening the bonding effect.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of dry preparation of a positive electrode sheet for a lead-carbon battery, characterized by, The application relates to a lead-carbon battery positive plate prepared by a dry method. The acid solution is selected from a sulfuric acid solution. The dry powder is applied to both sides of the metal grid, pressed and placed in an acid solution for soaking, then taken out, flattened, and solidified; the mass ratio of the lead powder to the polytetrafluoroethylene is 100: (5-15); the pressure for the pressing and compacting is 0.6-0.8 MPa, and the time is 8-12 min; the concentration of the acid solution is 1.0 g·L -1 -1.2 g·L -1 ; the soaking time is 8-12 min.

2. The method of producing a lead-carbon battery positive electrode plate by a dry method according to claim 1, characterized in that, And / or, the metal grid is selected from a lead alloy grid. The material further comprises one or more of red lead, activated carbon, polypropylene fiber and carbon fiber.

3. The method of producing a lead-carbon battery positive electrode sheet by a dry process according to claim 1 or 2, characterized by, The mass ratio of the lead powder, the red lead, the activated carbon, the polypropylene fiber and the carbon fiber is 100: (1-3): (0.3-0.5): (0.1-0.3): (0.1-0.3).

4. The method of producing a lead-carbon battery cathode electrode plate by a dry method according to claim 3, characterized in that, The lead-carbon battery positive plate is prepared by the method of any one of claims 1-4.

5. A positive electrode sheet for a lead-carbon battery, characterized by comprising: And / or, the pore size of the lead-carbon battery positive plate is 2nm-50nm.

6. The positive electrode plate of the lead-carbon battery according to claim 5, characterized in that, The specific surface area of the positive active material of the positive electrode plate of the lead-carbon battery is 5m 3 ·g -1 -6m 3 ·g -1 ; And / or, the hole volume of the positive pole piece of the lead-carbon battery is 0.002cm 3 ·g -1 -0.006cm 3 ·g -1 ; The application further relates to a lead-carbon battery positive plate comprising the positive plate of claim 5 or 6.

7. A lead carbon battery, characterized by, ​

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