Spinel cobalt-based catalytic positive electrode material for aluminum-sulfur battery and preparation method and application thereof

Abstract

The application belongs to the technical fields of aluminum-sulfur battery electrode material preparation and energy storage battery, and particularly relates to a spinel cobalt-based catalytic positive electrode material for aluminum-sulfur battery and a preparation method and application thereof. The application constructs a cobalt-based catalytic material with a spinel crystal structure through structure regulation and control, and applies the material to a positive electrode system of an aluminum-sulfur battery after sulfidation. The prepared cobalt-aluminum oxygen catalytic material has a stable spinel crystal lattice structure, and the tetrahedral sites and octahedral sites in the material are cooperatively distributed with double high-spin active centers of metals, through compounding with a high-conductivity carbon material, a high-efficiency electron transport network is constructed, so that the electrode reaction kinetics is significantly improved, the aluminum polysulfide intermediates generated in the reaction process of the aluminum-sulfur battery can be effectively adsorbed, and the oxidation-reduction conversion reaction is promoted, so that the polysulfide migration is inhibited and the reaction kinetics is accelerated, the electrochemical polarization is reduced, and the cycle stability is improved. The process is simple, the conditions are mild, and the application has good repeatability and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-sulfur battery electrode material preparation and energy storage battery technology, specifically relating to a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries, its preparation method and application. Background Technology

[0002] Aluminum-sulfur batteries, as a novel multi-electron energy storage system, have attracted widespread attention in recent years due to the abundance of aluminum resources, high safety, and high theoretical energy density. Aluminum enables multi-electron transfer processes in electrochemical reactions, giving aluminum-sulfur batteries high theoretical energy density and large specific capacity. Simultaneously, sulfur is abundant and inexpensive, making aluminum-sulfur batteries a promising candidate for large-scale and high-energy-density energy storage applications.

[0003] Despite the significant advantages of aluminum-sulfur batteries, their practical application still faces serious challenges. Research indicates that during charge and discharge, the reaction between the sulfur cathode and aluminum ions generates a series of soluble aluminum polysulfide intermediates (such as Al₂S₃). x These polysulfides readily dissolve in the electrolyte and, driven by the concentration gradient, undergo a shuttle effect, diffusing towards the negative electrode and undergoing parasitic reactions. This leads to irreversible loss of the active sulfur cathode material, causing rapid capacity decay in the battery. Simultaneously, elemental sulfur and its final discharge product, aluminum sulfide (Al2S3), have extremely poor electronic conductivity, and the conversion kinetics of polysulfides to Al2S3 are sluggish, resulting in severe electrode polarization and poor rate performance. This severely restricts the cycle life and practical application of aluminum-sulfur batteries.

[0004] To address these issues, researchers are dedicated to developing functionalized cathode materials. Through strategies such as constructing porous conductive frameworks and introducing polar catalysts, they aim to achieve strong anchoring and rapid conversion of polysulfides. Among these, polar materials such as metal oxides and sulfides are widely used to regulate the interfacial reactions of polysulfides due to their strong chemisorption properties. For example, Chinese patent CN110993961A proposes a core-shell type cobalt octasulfide (Co9S8) nanoparticle composite nitrogen-sulfur co-doped carbon nanofiber material, prepared through electrospinning and heat treatment, primarily for use as the cathode in lithium-oxygen or aluminum-air batteries. This technology enhances conductivity by forming a carbon coating structure and increases active sites using cobalt sulfide nanoparticles. However, this material is mainly designed for oxygen reactions, and its catalytic mechanism relies on the regulation of oxygen intermediates. It does not provide an effective solution for the unique aluminum polysulfide shuttle problem and conversion kinetics in aluminum-sulfur battery systems. Furthermore, its preparation process involves electrospinning and complex heat treatment, making it relatively cumbersome and difficult to control costs.

[0005] For example, Chinese patent CN118630211A discloses a catalyst based on the chiral spin-selective effect, which uses chiral molecules intercalated into molybdenum disulfide for use in aluminum-sulfur batteries. This technical solution utilizes the spin-selective effect of chiral molecules to accelerate reaction activity, achieving rapid charge-discharge and ultra-high cycle stability. This method provides a new approach to aluminum-sulfur battery catalysis from a quantum spin perspective. However, the synthesis and intercalation process of chiral molecules is usually subject to harsh conditions and complex steps, and the stability of chiral molecules in long-term electrochemical environments and the regulation of their adsorption capacity for polysulfides still need further verification.

[0006] Comprehensive analysis reveals that existing technologies for applying to aluminum-sulfur battery cathode catalytic materials generally suffer from the following shortcomings: First, the function of catalytic materials often focuses on the single physical / chemical adsorption of polysulfides or the promotion of single conversion kinetics, making it difficult to achieve effective synergy between adsorption and catalysis. Second, the preparation process of some high-performance materials involves complex processes such as electrospinning and hydrothermal intercalation, resulting in high costs, poor reproducibility, and hindering commercial applications. Therefore, developing a catalytic cathode material with stable structure, simple preparation process, and the ability to simultaneously achieve efficient adsorption and rapid conversion of aluminum polysulfides is of great significance for promoting the practical application of aluminum-sulfur batteries. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries, its preparation method, and its application. By selecting a spinel-structured cobalt-aluminum-oxygen catalytic material as the core catalyst, and utilizing the synergistic distribution of tetrahedral and octahedral sites in its crystal lattice, a unique active center structure is formed. The prepared spinel-type cobalt-based catalytic cathode material can effectively improve the electrochemical performance and cycle stability of aluminum-sulfur batteries. This invention prepares the cobalt-aluminum-oxygen precursor via a sol-gel method and constructs a spinel catalytic material with a specific structure through a two-step heat treatment. The preparation process is simple, mild, and highly reproducible.

[0008] The technical solution adopted is as follows:

[0009] A method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries includes the following steps:

[0010] (1) Dissolve the cobalt source and aluminum source in deionized water to form a homogeneous solution, and add a complexing agent to the solution to form a homogeneous sol system under heating and stirring conditions;

[0011] (2) The obtained sol system was dried under heating conditions to obtain a gel precursor;

[0012] (3) The obtained gel precursor is subjected to two-step heat treatment. The first calcination is carried out under the first temperature condition to obtain the spinel structure precursor material. Then, the second calcination is carried out under the second temperature condition to transform it into a cobalt aluminum oxygen catalyst material with a spinel structure. The spinel structure contains co-distributed tetrahedral sites and octahedral sites.

[0013] (4) The catalytic material prepared in step (3) is mixed with conductive carbon material, ultrasonically dispersed in an organic solvent, and then dried to obtain a composite catalyst;

[0014] (5) The composite catalyst obtained in step (4) is mixed with elemental sulfur and heated under an inert atmosphere to uniformly load sulfur onto the surface of the catalyst material, thereby obtaining a spinel-type cobalt-based catalytic cathode material.

[0015] Preferably, in step (1), the cobalt source includes one or more of cobalt nitrate hexahydrate, cobalt sulfate, cobalt chloride, and cobalt acetate; the aluminum source includes one or more of aluminum nitrate nonahydrate, aluminum sulfate, and aluminum isopropoxide; the molar ratio of cobalt to aluminum is 1:2; the heating temperature is 40-60℃; and the complexing agent is selected from any one of citric acid, oxalic acid, tartaric acid, ethylene glycol, triethanolamine, urea, or 1,2-epoxypropane.

[0016] Preferably, in step (2), the sol system is dried at 70-90°C for 10-12 h.

[0017] Preferably, in step (3), the calcination is carried out in an air atmosphere; the first calcination temperature is 400-450℃, yielding a product containing tetrahedral Co. 2+ With octahedral low-spin Co 3+ The coexisting spinel structure materials have a 1:1 ratio; the second calcination temperature is 600–650℃, which allows the Co at the octahedral sites to... 3+ A low-spin to high-spin transition occurs, forming a double high-spin tetrahedron Co. 2+ (Td)-O-octahedral Co 3+ (Oh) Collaborative structure.

[0018] Preferably, in step (4), the conductive carbon material is one or more of Ketjen black, carbon nanotubes, graphene, acetylene black, and mesoporous carbon, the mass ratio of the catalytic material to the conductive carbon material is 1:3, and the ultrasonic dispersion time is 1 to 2 h; the solvent is anhydrous ethanol or deionized water.

[0019] Preferably, in step (5), the mass ratio of sulfur to the composite catalyst is 1:1, the heating temperature is 155–170°C, the heating time is 10–12 h, and the inert atmosphere is argon; the sulfur content in the cathode material is 45–50 wt%, and the sulfur loading is 0.8–1.2 mg cm⁻¹.-2 .

[0020] The present invention also provides a spinel-type cobalt-based catalytic cathode material, which is prepared by the aforementioned preparation method.

[0021] The present invention provides a spinel-type cobalt-based catalytic cathode material that can be used to prepare aluminum-sulfur battery cathodes. The process is as follows: the spinel-type cobalt-based catalytic cathode material is used as an active material, mixed with a conductive agent and a binder, and added to a solvent to form a uniform slurry. The slurry is coated on the surface of a current collector and dried to obtain an aluminum-sulfur battery cathode.

[0022] Preferably, the conductive agent is Super P, the binder is polyvinylidene fluoride, and the mass ratio of the active material, conductive agent and binder is 7:2:1; the organic solvent is any one of NMP (N-methylpyrrolidone), NEP (N-ethylpyrrolidone), GBL (γ-butyrolactone), and NFM (N-formylmorpholine); the current collector is molybdenum foil, the drying temperature is 70°C, and the drying time is 10-12 h.

[0023] The present invention also provides an aluminum-sulfur battery, wherein the aluminum-sulfur battery includes the aluminum-sulfur battery positive electrode prepared by the present invention.

[0024] In this invention, tetrahedral Co is constructed in the material by inducing coordination environment regulation of metal ions in the spinel lattice through two-step heat treatment. 2+ With octahedral Co 3+ A synergistically distributed dual high-spin active site structure. This structure can effectively adsorb polysulfide intermediates generated during the aluminum-sulfur battery reaction and promote their redox conversion process, thereby reducing the adverse effects of polysulfide migration. At the same time, it accelerates the electrochemical reaction kinetics, enabling the aluminum-sulfur battery to have high active material utilization, low electrochemical polarization, and good cycle stability.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1) The spinel cobalt-aluminum-oxygen catalytic material prepared in this invention forms a synergistic structure of tetrahedral and octahedral sites through specific heat treatment (such as spin state modulation). This structure can strongly chemically adsorb soluble polysulfides generated in aluminum-sulfur batteries, anchoring them to the positive electrode side; at the same time, these sites can also serve as catalytic active centers, accelerating the conversion of adsorbed polysulfides to the final product (Al2S3), avoiding excessive accumulation of polysulfides in the electrolyte and shuttle migration to the negative electrode, fundamentally reducing the loss of active materials, thereby significantly improving the coulombic efficiency and cycle stability of the battery.

[0027] 2) The spinel-structured cobalt-aluminum-oxygen catalytic material prepared in this invention not only exhibits superior conductivity compared to elemental sulfur, but more importantly, its catalytic effect lowers the activation energy of polysulfide redox reactions. Furthermore, by combining it with highly conductive Ketjen Black (such as EC-600JD), a highly efficient electron transport network is constructed, thereby significantly improving electrode reaction kinetics and reducing electrochemical polarization.

[0028] 3) In this invention, because the catalytic material has a good dispersion and anchoring effect on sulfur and its polysulfides, the active substance sulfur can be more uniformly loaded on the surface of the catalytic material and be more fully utilized in the reaction, so that the actual discharge specific capacity is closer to the theoretical specific capacity of sulfur, giving full play to the high energy density advantage of aluminum-sulfur batteries.

[0029] 4) The spinel structure itself has extremely high crystallographic and electrochemical stability. During long-term charge and discharge processes, this structure is not prone to collapse or phase transition, ensuring the structural integrity of the cathode material during long cycles. This allows the battery to maintain a high capacity after hundreds or even thousands of cycles, significantly extending the battery's lifespan.

[0030] 5) The spinel-structured cobalt-aluminum-oxygen catalytic material prepared in this invention possesses a stable crystal structure and a strong polar interface. During the aluminum-sulfur battery reaction, it not only exhibits strong chemisorption of polysulfide intermediates but also promotes their reversible transformation, thereby reducing the adverse effects of polysulfide diffusion and migration and improving the reaction kinetics at the electrode interface. The aluminum-sulfur battery cathode constructed using this catalytic material demonstrates excellent rate performance and cycle stability while maintaining a high specific capacity.

[0031] 6) This invention employs a sol-gel method combined with a two-step heat treatment process to prepare spinel-structured catalytic materials. By controlling key parameters such as precursor composition, drying conditions, and calcination temperature, stable construction of the material's crystal structure and active site distribution can be achieved. This method utilizes widely available raw materials, employs mild preparation conditions, and has a simple process flow, demonstrating good reproducibility and potential for large-scale application. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the preparation method of a double high spin spinel structure catalytic cathode material for aluminum-sulfur batteries provided in Embodiment 1 of the present invention.

[0033] Figure 2 This is an X-ray diffraction pattern of the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in Example 1 of this invention.

[0034] Figure 3 This is a SEM image of the spinel-structured cobalt aluminum oxide catalytic material prepared in Example 1 of this invention.

[0035] Figure 4 This is a TEM-EDS (energy-dispersive X-ray spectroscopy) image of the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in Example 1 of this invention.

[0036] Figure 5 This is the spin density diagram of the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in Example 1 of this invention.

[0037] Figure 6 This is a schematic diagram of the soft-pack battery prepared in Embodiment 1 of the present invention; wherein, a is a schematic diagram of the overall soft-pack, and b is a schematic diagram of the internal structure of the soft-pack in longitudinal section.

[0038] Figure 7 This is a graph showing the cycling performance of the aluminum-sulfur battery prepared in Example 1 of this invention at a current density of 1 C.

[0039] Figure 8 This is the X-ray diffraction pattern of the spinel aluminum-sulfur battery catalyst prepared in Comparative Example 1.

[0040] Figure 9 This is a spin density diagram of the spinel aluminum-sulfur battery catalyst prepared in Comparative Example 1.

[0041] Figure 10 The tetrahedral Co prepared using Comparative Example 2 2+ High-spin, octahedral Co 3+ The graph shows the cycling performance of an aluminum-sulfur battery with a low-spin spinel modified cathode at a current density of 1 C.

[0042] Figure 11 The graph shows the cycling performance of an aluminum-sulfur battery with a tetrahedral site-modified spinel cathode prepared in Comparative Example 3 at a current density of 1C.

[0043] Figure 12 This is a comparison of the cycling performance of the aluminum-sulfur battery prepared in Example 1 and the aluminum-sulfur battery modified with the conductive carbon material Ketjen black catalyst prepared in Comparative Example 4 at a current density of 1C. Detailed Implementation

[0044] The accompanying drawings are for illustrative purposes only. To enable those skilled in the art to better understand the technical solutions in this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0045] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0046] It should be understood that the prior art used in this invention may be omitted; unless otherwise specified, the materials and testing methods used are commercially available and can be measured by conventional methods.

[0047] Example 1.

[0048] like Figure 1 As shown, a method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries includes the following steps:

[0049] (1) Dissolve 2.91 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 7.50 g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O) in 100 mL of deionized water. Then add citric acid as a complexing agent to the solution and stir magnetically at 50°C to gradually form a homogeneous and transparent sol system.

[0050] (2) The sol system obtained in step (1) is placed in an oven at 80°C and dried for 12 h to gradually form a gel precursor.

[0051] (3) The obtained gel precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min under air atmosphere and held for 2 h for the first calcination to obtain spinel structure precursor material.

[0052] (4) The material obtained in step (3) is further heated to 600℃ in air and held for 2 h for a second calcination to allow the Co at the octahedral sites in the material to be calcined. 3+ A spin-state transition occurs, resulting in the formation of a double high-spin tetrahedron Co. 2+ (Td)-O-octahedral Co 3+ (Oh) Spinel-structured cobalt aluminum oxygen catalytic material with synergistic structure.

[0053] like Figure 2 The figure shows the X-ray diffraction pattern of the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in Example 1. As can be seen from the figure, the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in this invention has high crystallinity and appears to be an amorphous material. Its scanning electron microscope image is shown below. Figure 3 As shown, its TEM-EDS (energy-dispersive X-ray spectroscopy) image is as follows: Figure 4 As shown, the spin density map is as follows Figure 5 As shown, this demonstrates the successful synthesis of the spin spinel Co-Al-O (cobalt aluminum oxide) catalytic material prepared in Example 1.

[0054] The specific process for preparing sulfur-catalyst composite materials (i.e., spinel-type cobalt-based catalytic cathode materials) using the prepared spinel-structured cobalt-aluminum-oxygen catalytic material is as follows:

[0055] (5) The catalyst obtained in step (4) is mixed with the conductive carbon material Ketjen black at a mass ratio of 1:3, and 30 ml of ethanol is added for ultrasonic dispersion for 2 h. Then it is dried at 60 °C to obtain the composite catalyst.

[0056] (6) The obtained composite catalyst was mixed with sublimed sulfur at a mass ratio of 1:1 and heated at 155 °C for 12 h under an argon protective atmosphere to uniformly load sulfur onto the surface of the catalyst material, thereby obtaining a spinel-type cobalt-based catalytic cathode material.

[0057] Using the obtained spinel-type cobalt-based catalytic cathode material, an aluminum-sulfur battery cathode was prepared and assembled into an aluminum-sulfur battery. The specific process is as follows:

[0058] The obtained spinel-type cobalt-based catalytic cathode material was used as the active material and mixed with the conductive agent Super P and the binder polyvinylidene fluoride at a mass ratio of 7:2:1. N-methylpyrrolidone (NMP) was added to form a uniform slurry. The total mass ratio of the active material, conductive agent and binder to N-methylpyrrolidone was 1:3.

[0059] The obtained slurry was uniformly coated onto the surface of the molybdenum foil current collector and dried under vacuum at 70°C for 12 h to obtain the positive electrode of the aluminum-sulfur battery.

[0060] The aluminum-sulfur battery of the present invention includes the aluminum-sulfur battery positive electrode prepared above, and also includes an electrolyte and a negative electrode.

[0061] The prepared spinel-type cobalt-based catalytic cathode material contains approximately 50 wt% sulfur and has a sulfur loading of approximately 1.0 mg cm⁻¹. -2 The prepared aluminum-sulfur battery cathode was cut into strips. Only the electrolyte was prepared by mixing 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum chloride (AlCl3) to form an ionic liquid electrolyte, with a molar ratio of AlCl3 to EMImCl of 1.3:1. All electrolytes were prepared under an inert atmosphere (argon) and thoroughly stirred until a homogeneous and transparent solution was formed.

[0062] In a glove box filled with high-purity argon gas (O2 and H2O < 0.1 ppm), the prepared aluminum-sulfur battery positive electrode, electrolyte, and aluminum foil negative electrode were assembled into an aluminum-sulfur pouch battery. The separator used was a commercially available glass fiber membrane GF-C. A schematic diagram of the pouch battery is shown below. Figure 6 As shown.

[0063] Electrochemical performance was tested using a Xinwei Battery Testing System (CT-4008T-5V20 mA-164, Shenzhen, China) at room temperature using a constant current charge-discharge test with a voltage window of 0.01–1.8 V. Current density was calculated based on the mass of active material. All batteries were allowed to stand for 12 hours before testing to ensure that the electrolyte fully wetted the electrodes.

[0064] The cycle performance of the aluminum-sulfur battery modified with spinel-type cobalt-based catalytic cathode material prepared in Example 1 at a 1C current density is as follows: Figure 7 As shown, it can be seen that the aluminum-sulfur battery achieves a stable cycle count of 3000 cycles under the action of the modified positive electrode of the new aluminum-sulfur battery.

[0065] Comparative Example 1: A method for preparing a cathode catalyst modified with a non-double high-spin spinel material, comprising the following steps:

[0066] (1) Dissolve 2.91 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 7.50 g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O) in 100 mL of deionized water. Then add an appropriate amount of citric acid as a complexing agent to the solution and continuously stir magnetically at 50°C to gradually form a homogeneous and transparent sol system.

[0067] (2) The sol obtained in step (1) is placed in an oven at 80 °C and dried for 12 h to gradually form a gel-like precursor.

[0068] (3) The obtained gel precursor was placed in a muffle furnace and heated to 400 °C at a heating rate of 5 °C / min under air atmosphere and held for 2 h for the first calcination to obtain spinel structure precursor material.

[0069] (4) The material obtained in step (3) is not subjected to a second calcination. The Co at the octahedral sites in the material 3+ No spin state transition occurs, thus forming a tetrahedral high-spin Co. 2+ (Td), with low-spin octahedral Co 3+ (Oh) Spinel-structured cobalt aluminum oxygen catalytic material with non-synergistic structure.

[0070] The X-ray diffraction pattern of the spinel aluminum-sulfur battery catalyst prepared in Comparative Example 1 is shown below. Figure 8 As shown in the figure, the material prepared in Comparative Example 1 still possesses the Co-Al-O spinel structure, but its spin density diagram is as follows: Figure 9 As shown, the Co at the octahedral position is a low-spin state, proving that the spinel catalyst prepared in Comparative Example 1 did not form a double high-spin structure and could not effectively improve the cathode of aluminum-sulfur batteries.

[0071] Comparative Example 2, a tetrahedral Co2+ High-spin, octahedral Co 3+ The method for preparing low-spin spinel materials differs from Example 1 in that the spinel material synthesis involves only one calcination step at 400°C.

[0072] Finally, the prepared spinel-type cobalt-based catalytic cathode material was used to prepare the battery cathode, and the battery was assembled into an aluminum-sulfur battery.

[0073] Other areas not mentioned are the same as in Example 1.

[0074] Constant current charge-discharge measurements were performed using the Xinwei Battery Testing System (CT-4008T-5V20 mA-164, Shenzhen, China) at room temperature ranging from 0.01V to 1.8V, with a current of 1C (1C=1675mAh / g). All batteries were allowed to stand for 12 hours before testing.

[0075] like Figure 10 As shown in the test, the aluminum-sulfur battery prepared in Comparative Example 2 had extremely low capacity after 480 cycles under the modified positive electrode of the aluminum-sulfur battery prepared in this embodiment.

[0076] Comparative Example 3, a method for preparing a spinel material modified cathode with only tetrahedral sites, differs from Example 1 in that the spinel material synthesis involves only one calcination step at 800°C.

[0077] Other areas not mentioned are the same as in Example 1.

[0078] The aluminum-sulfur battery prepared in Comparative Example 3, under the modified positive electrode of the aluminum-sulfur battery prepared in this embodiment, exhibited the following cycle performance at a 1C current density: Figure 11 As shown, it can be seen that the capacity of aluminum-sulfur batteries remains low even after 500 stable cycles.

[0079] Comparative Example 4: A positive electrode was prepared using conductive carbon material Ketjen black as a catalyst, and then assembled into an aluminum-sulfur battery; the specific steps included:

[0080] S1. Mix 14 mg Ketjen black, 4 mg Super P and 2 mg polyvinylidene fluoride (PVDF) and grind them thoroughly, then add an appropriate amount of N-methylpyrrolidone (NMP) solvent to form a homogeneous slurry.

[0081] S2. Coat the obtained uniform slurry onto the surface of the molybdenum foil current collector, controlling the coating thickness to be approximately 0.1 mm.

[0082] S3. Place the coated electrode in a vacuum oven and dry it at 70 °C for 12 h to allow the residual NMP solvent to fully evaporate. Then cut the dried electrode to an appropriate size for battery assembly.

[0083] The electrolyte is an ionic liquid electrolyte formed by mixing 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum chloride (AlCl3), wherein the molar ratio of AlCl3 to EMImCl is 1.3:1. In a glove box filled with high-purity Ar gas (O2 and H2O < 0.1 ppm), the prepared positive electrode, electrolyte, and aluminum foil negative electrode are assembled into an aluminum-sulfur pouch battery.

[0084] Constant current charge-discharge tests were conducted at room temperature using the Xinwei Battery Testing System (CT-4008T-5V20 mA-164, Shenzhen, China). The voltage range was 0.01–1.8 V, and the current density was calculated based on the mass of the active material. All batteries were allowed to stand for 12 hours before testing.

[0085] The cycle performance of the aluminum-sulfur battery constructed with the spinel-structured catalytic cathode material prepared in Example 1 and the aluminum-sulfur battery constructed with the carbon material cathode in Comparative Example 4 under the same conditions is as follows: Figure 12 As shown in the figure, the spinel-structured catalytic material described in Example 1 can significantly improve the electrochemical performance of aluminum-sulfur batteries. Under the same current density conditions, the aluminum-sulfur battery constructed using the catalytic material of this invention exhibits a higher initial specific capacity and better cycle stability, while the comparative battery using carbon materials as catalysts has a significantly lower capacity and faster degradation.

[0086] The results show that the spinel-structured cobalt-aluminum-oxygen catalytic material prepared in this invention can effectively promote the adsorption and conversion of polysulfides during the aluminum-sulfur battery reaction, thereby improving the utilization rate of active materials and reducing battery polarization, so that the battery can maintain high capacity and stability during long-term cycling.

[0087] Example 2.

[0088] A method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries differs from Example 1 in that the cobalt source is cobalt chloride, the aluminum source is aluminum sulfate, and the complexing agent is ethylene glycol.

[0089] Other areas not mentioned are the same as in Example 1.

[0090] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries, characterized in that, Includes the following steps: (1) Dissolve the cobalt source and aluminum source in deionized water to form a homogeneous solution, and add a complexing agent to the solution to form a homogeneous sol system under heating and stirring conditions; (2) The obtained sol system was dried under heating conditions to obtain a gel precursor; (3) The obtained gel precursor was subjected to a two-step heat treatment. The calcination was carried out in an air atmosphere, and the first calcination was carried out at 400-450℃ to obtain a gel containing tetrahedral Co. 2+ With octahedral low-spin Co 3+ The coexisting spinel structure materials, in a 1:1 ratio, are then subjected to a second calcination at 600–650℃ to allow the Co at the octahedral sites to be exposed. 3+ A low-spin to high-spin transition occurs, transforming it into a cobalt-aluminum-oxygen catalytic material with a spinel structure; this spinel structure contains cooperatively distributed tetrahedral and octahedral sites, forming a double high-spin tetrahedral Co. 2+ -O-octahedron Co 3+ Collaborative structure; (4) The catalytic material prepared in step (3) is mixed with conductive carbon material, ultrasonically dispersed in a solvent and then dried to obtain a composite catalyst; (5) The composite catalyst obtained in step (4) is mixed with elemental sulfur and heated under an inert atmosphere to uniformly load sulfur onto the surface of the catalyst material, thereby obtaining a spinel-type cobalt-based catalytic cathode material.

2. The method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries according to claim 1, characterized in that, In step (1), the cobalt source includes one or more of cobalt nitrate hexahydrate, cobalt sulfate, cobalt chloride, and cobalt acetate; the aluminum source includes one or more of aluminum nitrate nonahydrate, aluminum sulfate, and aluminum isopropoxide; the molar ratio of cobalt to aluminum is 1:2; the heating temperature is 40-60℃; and the complexing agent is selected from any one of citric acid, oxalic acid, tartaric acid, ethylene glycol, triethanolamine, urea, or 1,2-epoxypropane.

3. The method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries according to claim 1, characterized in that, In step (2), the sol system is dried at 70-90°C for 10-12 h.

4. The method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries according to claim 1, characterized in that, In step (4), the conductive carbon material is one or more of Ketjen black, carbon nanotubes, graphene, acetylene black, and mesoporous carbon, the mass ratio of the catalytic material to the conductive carbon material is 1:3, and the ultrasonic dispersion time is 1 to 2 h; the solvent is anhydrous ethanol or deionized water.

5. The method for preparing a spinel-type cobalt-based catalytic cathode material for aluminum-sulfur batteries according to claim 1, characterized in that, In step (5), the mass ratio of sulfur to the composite catalyst is 1:1, the heating temperature is 155–170°C, the heating time is 10–12 h, and the inert atmosphere is argon; the sulfur content in the cathode material is 45–55 wt%, and the sulfur loading is 0.8–1.2 mg cm⁻¹. -2 .

6. The spinel-type cobalt-based catalytic cathode material prepared by the preparation method according to any one of claims 1-5.

7. The application of the spinel-type cobalt-based catalytic cathode material as described in claim 6 in the preparation of aluminum-sulfur battery cathodes, characterized in that, A spinel-type cobalt-based catalytic cathode material is used as the active material, mixed with a conductive agent and a binder, and an organic solvent is added to form a uniform slurry. The slurry is then coated onto the surface of a current collector and dried to obtain an aluminum-sulfur battery cathode.

8. The application according to claim 7, characterized in that, The conductive agent is Super P, the binder is polyvinylidene fluoride, and the mass ratio of the active material, conductive agent and binder is 7:2:1; the organic solvent is any one of NMP, NEP, GBL and NFM; the current collector is molybdenum foil, the drying temperature is 70 ℃, and the drying time is 10 to 12 h.

9. An aluminum-sulfur battery, characterized in that, Including the aluminum-sulfur battery cathode prepared according to claim 7 or 8.

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