A long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method

Abstract

This invention proposes a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. This invention relates to the field of seawater battery technology and includes the following steps: S1, mixing lead chloride, a composite carbon source, and pure water, and then centrifugally spray-drying to obtain a precursor; S2, sintering and air-jet crushing the precursor in an inert gas atmosphere to obtain a first cathode material; S3, mixing the first cathode material, a binder, a co-solvent, and pure water, and then drying to obtain a second cathode material; S4, rolling, drying, and cutting the second cathode material into cathode sheets, wrapping the cathode sheets with a current collector, and pressing them into a cathode assembly. The preparation method provided by this invention allows lead chloride to fully contact the conductive carbon layer, improving the conductivity of the material, thereby improving the capacity performance and working life of the magnesium seawater activated battery, ensuring long-term stable operation of marine equipment.

Description

Technical Field

[0001] This invention relates to the field of seawater battery technology, and in particular to a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. Background Technology

[0002] Magnesium-seawater activated batteries emerged in the 1940s. Their most prominent feature is that they do not require a separate electrolyte, utilizing natural seawater as the electrolyte. A magnesium-seawater activated battery is a primary cell, typically using magnesium or magnesium alloys as the negative electrode, metal chlorides (CuCl, AgCl, PbCl2) as the positive electrode active material, and seawater as the electrolyte solution. A circuit is formed by connecting a load, and electrical energy is provided by the continuous dissolution of the metal. The characteristics of magnesium-seawater batteries enable them to play an important role in marine exploration, resource utilization, and marine military defense. With terrestrial resources gradually depleting, the development and application of magnesium-seawater activated batteries are of profound significance for humanity's development and utilization of marine resources.

[0003] Magnesium-seawater activated battery systems mainly include magnesium-silver, magnesium-lead, and magnesium-copper systems. In magnesium-silver and magnesium-copper systems, the cathodes use precious metals silver and copper, resulting in high battery costs and hindering commercialization. Furthermore, the silver chloride and cuprous iodide in these systems are easily decomposed by light, preventing the batteries from meeting practical application requirements. Additionally, in copper systems, the copper atoms generated during discharge tend to adhere to the magnesium plate surface, affecting further chemical reactions and causing premature voltage drops, thus limiting their application. The magnesium-lead chloride system, however, offers advantages such as low cost and stable performance, meeting the demand for high-performance, low-cost magnesium-seawater batteries.

[0004] Lead chloride has poor conductivity, affecting the electrochemical performance and lifespan of batteries. Patent (CN111640906B) discloses a high-energy-density, fast-activation positive electrode for seawater batteries and its preparation method. The positive electrode is composed of lead chloride, a binder, and a conductive agent. The preparation method includes the following steps: 1) ball milling; 2) powder mixing; 3) pressing; 4) wire bonding; 5) drying. The positive electrode sheet is precisely pressed to the appropriate process dimensions according to different battery models. However, this technical solution still has the following shortcomings: First, to improve conductivity, the patent mixes the conductive agent and lead chloride together mechanically. This physical composite method prevents lead chloride and the conductive agent from fully contacting each other. Second, the conductive agent used in this patent is metal conductive powder, carbon black, graphene, or carbon nanotubes. These conductive materials are expensive, especially metal conductive powder, graphene, and carbon nanotubes, which negate the low-cost advantage of the magnesium-lead chloride system. Third, due to the limitations of the physical composite method, its capacity performance and working life are low, failing to guarantee the long-term stable operation of marine equipment. Summary of the Invention

[0005] In view of this, the present invention proposes a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method, in order to solve the problems of insufficient contact between lead chloride and conductive agent materials, low capacity performance and low working life of existing magnesium seawater activated battery cathode assemblies.

[0006] The technical solution of this invention is achieved as follows: This invention provides a method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly, specifically including the following steps:

[0007] S1. Lead chloride, composite carbon source and pure water are mixed and centrifuged and spray-dried to obtain the precursor;

[0008] S2. The precursor is sintered and subjected to airflow abrasion treatment in an inert gas atmosphere to obtain the first cathode material;

[0009] S3. After mixing the first positive electrode material, binder, co-solvent and pure water, and drying, the second positive electrode material is obtained.

[0010] S4. The second positive electrode material is rolled, dried and cut into positive electrode sheets. The positive electrode sheets are wrapped with a current collector and pressed into a positive electrode assembly.

[0011] In this invention, in step S1, lead chloride is used as the raw material for preparing the battery positive electrode sheet, a composite carbon source is used as a conductive agent to provide conductivity, and pure water is used as a solvent to dissolve and mix the lead chloride and composite carbon source uniformly, thereby obtaining a precursor. In step S2, sintering the precursor promotes particle crystallization and forms the structure of the positive electrode material, while airflow ablation promotes the obtaining of a first positive electrode material with uniform particles. In step S3, the first positive electrode material is mixed with a binder to form a thin film, obtaining a second positive electrode material. The binder increases the viscosity of the first positive electrode material, making it easier to process and shape, while the addition of a co-solvent promotes better dissolution of the first positive electrode material and the binder in the solvent. In step S4, the dried product is rolled to form a uniform thin film, and the film thickness can be controlled; drying removes moisture from the film, making the film more stable; the positive electrode sheet is wrapped with a current collector, which provides a current conduction path, thereby improving the overall stability of the battery. The current collector can be any one of copper mesh, silver-plated copper mesh, or stainless steel mesh.

[0012] Based on the above technical solutions, preferably, step S1 specifically includes the following steps:

[0013] S11. Mix lead chloride, composite carbon source and pure water evenly to obtain the first solution;

[0014] S12. The first solution is ball-milled to obtain the second solution;

[0015] S13. The second solution is centrifuged and spray-dried to obtain the precursor.

[0016] Based on the above technical solutions, preferably, the amount of the composite carbon source added is 10wt% to 15wt% of the total amount of lead chloride.

[0017] Based on the above technical solutions, preferably, the composite carbon source includes a combination of polyvinylpyrrolidone or vinyl acetate and glucose, wherein the mass ratio of polyvinylpyrrolidone or vinyl acetate to glucose is 1:(1~1.5).

[0018] While magnesium-lead chloride (MgCl2) seawater batteries offer advantages such as low cost and stable performance, they are primarily disposable storage batteries. Lead chloride itself has poor conductivity, and directly using it to prepare seawater batteries results in poor electrochemical performance and a short lifespan. Mixing lead chloride with a composite carbon source composed of two organic carbon sources with different properties can, on the one hand, increase the conductivity of lead chloride, thereby improving the active capacity of the electrode. Glucose, as an organic carbon source, decomposes at high temperatures to produce carbon, while polyvinylpyrrolidone (PVP) possesses good conductivity and chemical stability. Specifically, during high-temperature sintering, the carbon formed after the decomposition of PPVP forms a network structure in the material, connecting the dispersed lead chloride particles. This carbon network structure provides more conductive channels, promoting electron transport and diffusion, thus improving the material's electronic conductivity. Simultaneously, the carbon network structure also increases the specific surface area of ​​the material, which is beneficial for electrolyte penetration and electron transport, thereby improving its electrochemical performance. On the other hand, compared with existing powdered conductive agents such as metal conductive powders, carbon black, graphite, and graphene, composite carbon sources have lower preparation costs and are more suitable for large-scale industrial production. Simultaneously, the composite carbon source and lead chloride are mixed more uniformly in a solid-liquid form, which can further promote the bonding between lead chloride and the conductive carbon layer, thereby improving the performance of seawater batteries. In this invention, controlling the amount of carbon source added to 10wt%–15wt% of the total lead chloride can improve the conductivity and electrochemical performance of the material; however, excessive carbon source may lead to a decrease in the specific capacity of the material. Controlling the mass ratio of polyvinylpyrrolidone to glucose to be 1:(1–1.5) can promote better uniformity and stability of the carbon source.

[0019] Based on the above technical solutions, preferably, the ball milling process includes coarse grinding and fine grinding. The process parameters for the coarse grinding and fine grinding processes include: a solid-liquid ratio of 40% to 50%, a rotation speed of 800 to 1000 rpm, and a time of 1 to 2 hours. The particle size of the zirconia beads used in the coarse grinding process is 6 to 8 mm, and the particle size of the zirconia beads used in the fine grinding process is 1 to 2 mm.

[0020] Directly mixing lead chloride with a carbon source only allows the carbon source to coat the surface of lead chloride, resulting in an unsatisfactory capacity release rate in the prepared seawater battery. However, by sequentially subjecting the first solution to coarse grinding, ball milling, and spray drying, small particles are encouraged to fill the gaps between large particles, increasing the specific surface area of ​​the bond between lead chloride and the composite carbon source. This further promotes the bonding between lead chloride and the conductive carbon layer, increases the active capacity of the positive electrode, improves the conductivity of lead chloride, and ultimately enhances the electrochemical performance and lifespan of the seawater battery.

[0021] Based on the above technical solutions, preferably, the sintering temperature in step S2 is 300-400℃ and the sintering time is 3-5h; the drying temperature in step S3 is 60-70℃ and the drying time is 18-20h.

[0022] Based on the above technical solutions, preferably, the mass ratio of the first positive electrode material, binder, co-solvent and pure water is (80-92):(2-12):(2-10):(6-15).

[0023] Based on the above technical solutions, preferably, the adhesive includes any one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, and microcrystalline cellulose; the co-solvent includes any one of ethanol or isopropanol. More preferably, the adhesive is a polytetrafluoroethylene emulsion with a mass concentration of 50% to 60%, and the co-solvent is ethanol. The polytetrafluoroethylene emulsion, as an adhesive, can bond the first cathode material particles together, thereby improving the structural stability of the cathode material; ethanol facilitates thorough mixing of the cathode material and the polytetrafluoroethylene emulsion to form a homogeneous mixture, and simultaneously, ethanol can rapidly evaporate during the drying process, accelerating the drying of the mixture.

[0024] Based on the above technical solutions, preferably, the thickness of the positive electrode sheet in step S4 is 1 to 3 mm.

[0025] A long-life, high-capacity magnesium seawater activated battery cathode assembly is prepared using the preparation method of a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in any of the preceding claims.

[0026] The long-life, high-capacity magnesium seawater activated battery cathode pack of the present invention has the following advantages over the prior art:

[0027] (1) This invention uses organic carbon source and polymer carbon source as composite carbon source, and promotes the composite carbon source to be uniformly coated on lead chloride material through ball milling and spray drying. On the one hand, the carbon source is sintered at high temperature in an inert atmosphere, and the carbon source is decomposed to form a conductive carbon layer, which is uniformly coated on the surface of lead chloride. On the other hand, polyvinylpyrrolidone, as a non-ionic polymer compound, can not only form a carbon layer on the surface of lead chloride material, but also form a carbon network to connect the dispersed materials and form a two-dimensional and three-dimensional conductive network, which further promotes the combination of lead chloride and conductive carbon layer, so that lead chloride can fully contact the conductive carbon layer, improve the conductivity of the material, and thus improve the capacity performance and working life of magnesium seawater activated battery, ensuring the long-term stable operation of marine equipment.

[0028] (2) The present invention uses organic carbon source glucose and polymer carbon source polyvinylpyrrolidone as composite carbon source. Compared with the existing technology that uses metal conductive powder, carbon black, carbon nanotubes and other conductive materials, it can not only reduce the preparation cost, but also facilitate large-scale industrial production. At the same time, the composite carbon source and lead chloride are mixed more uniformly in a solid-liquid form, which can further promote the combination of lead chloride and conductive carbon layer, thereby improving the electrochemical performance of seawater battery.

[0029] (3) Directly mixing lead chloride with carbon source only allows the carbon source to coat the surface of lead chloride. However, this invention performs coarse grinding, ball milling and spray drying on the first solution in sequence, which causes small particles to fill the gaps between large particles, increases the specific surface area of ​​lead chloride and composite carbon source, thereby further promoting the bonding between lead chloride and conductive carbon layer, increasing the active capacity of positive electrode, improving the conductivity of lead chloride, and thus improving the electrochemical performance and service life of seawater battery. Attached Figure Description

[0030] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The discharge curve of the positive electrode assembly of Example 10 of the present invention applied to a magnesium seawater activated battery;

[0032] Figure 2 The discharge curve of the positive electrode assembly of Embodiment 13 of the present invention applied to a magnesium seawater activated battery;

[0033] Figure 3 This is a discharge curve of the positive electrode assembly of Example 14 of the present invention applied to a magnesium seawater activated battery. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method, including the following steps:

[0037] S1. Weigh 36.5g of lead chloride and 4.1g of glucose and place them in a reaction vessel. Then add pure water to the reaction vessel and stir to dissolve to obtain the first solution.

[0038] S2. The first solution is centrifuged and spray-dried to obtain a precursor. The inlet air temperature of the spray dryer is 240°C and the outlet air temperature is 100°C. The precursor is sintered at 400°C under nitrogen atmosphere protection for 3 hours. The sintered product is then subjected to airflow crushing to obtain the cathode material.

[0039] S3. The positive electrode material, 60% polytetrafluoroethylene emulsion, ethanol and pure water are mixed evenly in a ratio of 85:8:6:10 and then dried at 70°C for 18 hours.

[0040] S4. Roll the dried product into a membrane of 3.3-3.4mm, then dry the membrane to remove moisture, cut it into a positive electrode sheet, wrap the positive electrode sheet with the cut current collector, put it into a mesh mold, and press it into a positive electrode assembly.

[0041] Example 2

[0042] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 1, except that in step S1, 36.5g of lead chloride and 4.1g of polyvinylpyrrolidone are weighed and placed in a reaction vessel.

[0043] Example 3

[0044] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 1, except that in step S1, 36.5g of lead chloride, 1.9g of polyvinylpyrrolidone and 2.2g of glucose are weighed and placed in a reaction vessel.

[0045] Example 4

[0046] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 3, except that in step S1, 41.0g of lead chloride, 1.9g of polyvinylpyrrolidone and 2.2g of glucose are weighed and placed in a reaction vessel.

[0047] Example 5

[0048] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 3, except that in step S1, 27.5g of lead chloride, 1.9g of polyvinylpyrrolidone and 2.2g of glucose are weighed and placed in a reaction vessel.

[0049] Example 6

[0050] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 3, except that in step S1, 36.5g of lead chloride, 2.05g of polyvinylpyrrolidone and 2.05g of glucose are weighed and placed in a reaction vessel.

[0051] Example 7

[0052] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 3, except that in step S1, 36.5g of lead chloride, 1.6g of polyvinylpyrrolidone and 2.5g of glucose are weighed and placed in a reaction vessel.

[0053] Example 8

[0054] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 3, except that step S1 includes the following steps:

[0055] S11. In step S1, weigh 36.5g of lead chloride, 1.9g of polyvinylpyrrolidone and 2.2g of glucose and place them in a reaction vessel. Then add pure water to the reaction vessel and stir to dissolve to obtain the first solution.

[0056] S12. The first solution is placed in a sand mill, and pure water is added to make the solid-liquid ratio of the first solution in the sand mill 50%. After coarse grinding at 1000 rpm for 2 hours, the second solution is obtained. The zirconium oxide beads used in the coarse grinding process of the sand mill have a particle size of 8 mm.

[0057] Example 9

[0058] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in embodiment 8, except that in step S12, the first solution is placed in a sand mill, and pure water is added to make the solid-liquid ratio of the first solution in the sand mill 50%. After coarse grinding at 1000 rpm for 2 hours, a second solution is obtained. The zirconium oxide beads used in the fine grinding process of the sand mill have a particle size of 3 mm.

[0059] Example 10

[0060] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 8, except that: in step S12, the first solution is placed in a sand mill, and pure water is added to make the solid-liquid ratio of the first solution in the sand mill 50%. The solution is coarsely ground at 1000 rpm for 2 hours and then finely ground at 1000 rpm for 2 hours to obtain the second solution. The zirconium oxide beads used in the coarse grinding process of the sand mill have a particle size of 8 mm, and the zirconium oxide beads used in the fine grinding process have a particle size of 3 mm.

[0061] Example 11

[0062] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 10, except that in step S3, the cathode material, polytetrafluoroethylene emulsion with a mass concentration of 60%, ethanol and pure water are mixed evenly in a part ratio of 80:8:6:10 and then dried.

[0063] Example 12

[0064] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method. The operation steps are the same as in Embodiment 10, except that in step S3, the cathode material, polytetrafluoroethylene emulsion with a mass concentration of 60%, ethanol and pure water are mixed evenly in a part ratio of 92:8:6:10 and then dried.

[0065] Example 13

[0066] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method, including the following steps:

[0067] S1:

[0068] S11. Weigh 35.5g of lead chloride, 1.7g of polyvinylpyrrolidone, and 1.7g of glucose and place them in a reaction vessel. Then add pure water to the reaction vessel and stir to dissolve to obtain the first solution.

[0069] S12. The first solution is placed in a sand mill, and pure water is added to make the solid-liquid ratio of the first solution in the sand mill 40%. The solution is coarsely ground at 800 rpm for 1 hour, and then finely ground at 800 rpm for 1 hour to obtain the second solution. The zirconium oxide beads used in the coarse grinding process of the sand mill have a particle size of 6 mm, and the zirconium oxide beads used in the fine grinding process have a particle size of 1 mm.

[0070] S2. The second solution is centrifuged and spray-dried to obtain a precursor. The inlet air temperature of the spray dryer is 220°C and the outlet air temperature is 90°C. The precursor is sintered at 300°C under nitrogen atmosphere protection for 5 hours. The sintered product is then subjected to airflow crushing to obtain the cathode material.

[0071] S3. The positive electrode material, 50% polytetrafluoroethylene emulsion, alcohol and pure water are mixed evenly in a ratio of 80:2:2:6 and then dried at 60°C for 20 hours.

[0072] S4. Roll the dried product into a film of 3.3-3.4mm, then dry the film to remove moisture and cut it into a positive electrode sheet; wrap the positive electrode sheet with the cut current collector mesh, put it into the mesh clamping mold, and press it into a positive electrode assembly.

[0073] Example 14

[0074] This embodiment discloses a long-life, high-capacity magnesium seawater activated battery cathode assembly and its preparation method, including the following steps:

[0075] S1:

[0076] S11. Weigh 36.2g of lead chloride, 2.04g of polyvinylpyrrolidone, and 3.06g of glucose and place them in a reaction vessel. Then add pure water to the reaction vessel and stir to dissolve to obtain the first solution.

[0077] S12. The first solution is placed in a sand mill. Pure water is added to make the solid-liquid ratio of the first solution in the sand mill 45%. The solution is then subjected to coarse grinding for 1.5 hours and fine grinding for 1.5 hours at a speed of 900 rpm to obtain the second solution. The zirconium oxide beads used in the coarse grinding process are 7 mm in diameter, and the zirconium oxide beads used in the fine grinding process are 2 mm in diameter.

[0078] S2. The second solution is centrifuged and spray-dried to obtain a precursor. The inlet air temperature of the spray dryer is 230°C and the outlet air temperature is 95°C. The precursor is sintered at 350°C under nitrogen atmosphere protection for 4 hours. The sintered product is then subjected to airflow crushing to obtain the cathode material.

[0079] S3. The positive electrode material, 55% polytetrafluoroethylene emulsion, alcohol and pure water are mixed evenly in a ratio of 92:12:10:15 and then dried at 65°C for 19 hours.

[0080] S4. Roll the dried product into a film of 3.3-3.4mm, then dry the film to remove moisture and cut it into a positive electrode sheet; wrap the positive electrode sheet with the cut current collector mesh, put it into the mesh clamping mold, and press it into a positive electrode assembly.

[0081] Comparative Example 1

[0082] This comparative example discloses a method for rapidly activating the positive electrode of a seawater battery and its preparation, referring to patent CN113328068A, which includes the following steps:

[0083] Lead chloride was placed in a ball mill jar, and the ball-to-powder ratio was controlled between 0.6:1 and 2:1. The mixture was ball-milled for 2 hours and then sieved. 33.47g of the ground lead chloride was taken, and 0.9g of carbon nanotubes were added. The mixture was ball-milled until homogeneous, and then polytetrafluoroethylene (PTFE) binder was added and stirred until homogeneous. The mixed cathode powder was loaded into a mold, and the press parameters were adjusted to press it into a cathode cake. The cathode cake was wrapped with a copper mesh, placed in a custom mold, and the press parameters were adjusted again to press it into a cathode sheet. The cathode sheet was baked at 70℃ for 21 hours to obtain a 3.3-3.4mm cathode sheet. The cathode sheet was then wrapped with a pre-cut current collector mesh, placed in a mesh-clamping mold, and pressed into a cathode assembly.

[0084] Performance testing

[0085] The positive electrode groups prepared in Examples 1-14 and Comparative Example 1, along with a magnesium plate, were used as the positive and negative electrodes of a seawater battery, respectively, forming a 13-string seawater battery. Positive and negative electrode leads were welded, and the battery pack's performance was tested. The test indicators included activation time, discharge duration, and discharge capacity at 500 mA. The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] Figures 1-3The discharge curves of the positive electrode assembly magnesium plate-matched single cells prepared in Examples 10, 13, and 14 are shown respectively. As can be seen from the figures, the discharge time exceeds 13 hours in the discharge voltage range of 1V-0.77V. The method of uniformly coating the material surface with mixed carbon sources in this invention can effectively improve the conductivity of the material. Simultaneously, particle size control and carbon coating can improve the capacity performance and discharge life of the magnesium-seawater battery. Table 1 shows that comparing Examples 1-3, it is evident that using polyvinylpyrrolidone and glucose as a mixed carbon source improves the conductivity of the positive electrode material compared to using them alone. Comparing Example 3 with Examples 4-7, it is evident that the composition and proportion of the carbon source affect the conductivity of the positive electrode material. Comparing Examples 8-10, it is evident that sequential coarse and fine grinding of the first solution further improves the conductivity of the positive electrode material. Comparing Example 10 with Examples 11 and 12, it is evident that the amount of positive electrode material added ultimately affects the capacity performance and discharge life of the magnesium-seawater battery.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly, characterized in that: Includes the following steps: S1. Lead chloride, composite carbon source and pure water are mixed and centrifuged and spray-dried to obtain the precursor; S2. The precursor is sintered and subjected to airflow abrasion treatment in an inert gas atmosphere to obtain the first cathode material; S3. After mixing the first positive electrode material, binder, co-solvent and pure water, and drying, the second positive electrode material is obtained. S4. The second positive electrode material is rolled, dried and cut into positive electrode sheets. The positive electrode sheets are wrapped with a current collector and pressed into a positive electrode assembly. Step S1 includes the following steps: S11. Mix lead chloride, composite carbon source, and pure water evenly to obtain a first solution; the composite carbon source comprises a combination of polyvinylpyrrolidone and glucose; the amount of composite carbon source added is 10wt%~15wt% of the total amount of lead chloride. S12. The first solution is ball-milled to obtain the second solution; the ball-milling process includes coarse milling and fine milling. S13. The second solution is centrifuged and spray-dried to obtain the precursor.

2. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 1, characterized in that: The mass ratio of polyvinylpyrrolidone to glucose is 1:(1~1.5).

3. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 1, characterized in that: The process parameters for the coarse grinding and fine grinding processes include: a solid-liquid ratio of 40% to 50%, a rotation speed of 800 to 1000 rpm, and a time of 1 to 2 hours. The zirconia beads used in the coarse grinding process have a particle size of 6 to 8 mm, and the zirconia beads used in the fine grinding process have a particle size of 1 to 2 mm.

4. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 1, characterized in that: In step S2, the sintering temperature is 300~400℃ and the sintering time is 3~5h; in step S3, the drying temperature is 60~70℃ and the drying time is 18~20h.

5. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 1, characterized in that: The mass ratio of the first positive electrode material, binder, co-solvent and pure water is (80~92):(2~12):(2~10):(6~15).

6. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 5, characterized in that: The adhesive includes any one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, and microcrystalline cellulose; the cosolvent includes any one of ethanol and isopropanol.

7. The method for preparing a long-life, high-capacity magnesium seawater activated battery cathode assembly as described in claim 1, characterized in that: The thickness of the positive electrode sheet mentioned in step S4 is 1~3mm.

8. A long-life, high-capacity magnesium seawater activated battery positive electrode pack, characterized in that: The positive electrode assembly is prepared using the method described in any one of claims 1 to 7 for preparing a long-life, high-capacity magnesium seawater activated battery positive electrode assembly.

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