A self-supporting composite sulfur positive electrode sheet, a preparation method and application thereof

Abstract

The application belongs to the technical field of electrochemical energy storage, and particularly relates to a self-supporting composite sulfur positive electrode sheet and a preparation method and application thereof. The self-supporting composite sulfur positive electrode sheet comprises a three-dimensional carrier and elemental sulfur filled in the three-dimensional carrier; the three-dimensional carrier comprises a three-dimensional conductive framework material and a metal nanomaterial loaded on the three-dimensional conductive framework material; and the filling amount of the elemental sulfur is 2-9 times the mass of the three-dimensional carrier. The self-supporting composite sulfur positive electrode sheet has the following beneficial effects: the three-dimensional conductive framework material in the three-dimensional carrier of the self-supporting composite sulfur positive electrode sheet cooperates with the metal nanomaterial to provide a continuous conductive network and a fast ion transmission channel, more sulfur can participate in effective reaction, and a water-based zinc battery exhibits excellent rate performance and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to a self-supporting composite sulfur cathode sheet, its preparation method, and its application. Background Technology

[0002] With the surge in global demand for renewable energy and sustainable energy storage systems, the development of highly safe, low-cost, and high-energy-density rechargeable battery technologies is crucial. Aqueous zinc-ion batteries are favored due to their low operating costs, non-flammability, environmental friendliness, and the high theoretical capacity (820 mAh g) of the zinc metal anode. -1 Sulfur cathodes exhibit significant application potential due to their advantages such as low oxidation-reduction potential (-0.76V vs. SHE). Among numerous cathode materials, sulfur cathodes stand out due to their extremely high theoretical specific capacity (1675mAh g / g). -1 With its abundant resources, low price, and non-toxicity, aqueous zinc-sulfur batteries are considered an ideal choice for building next-generation high-energy-density aqueous zinc-sulfur batteries. However, the commercial application of aqueous zinc-sulfur batteries is still constrained by a series of complex challenges related to the sulfur cathode and zinc anode themselves and their interfaces.

[0003] First, the discharge process of the sulfur cathode (S8) involves multiple electron transfers and multi-step solid-liquid-solid phase transitions. Elemental sulfur and its final discharge products (such as ZnS) have extremely low electronic conductivity, leading to severe electrode polarization and low utilization of active materials. Second, the intermediate products, soluble polysulfides (S... x 2- Sulfur readily dissolves in the electrolyte and diffuses to the zinc anode, causing irreversible side reactions that result in the loss of active material and corrosion of the zinc anode—a phenomenon known as the "shuttle effect." Furthermore, sulfur undergoes a significant volume change (>70%) during charge and discharge, easily leading to electrode structural pulverization and collapse, resulting in poor cycle stability. Even more serious is the fact that in aqueous electrolyte environments, polysulfides undergo a strong disproportionation reaction (2S₂O₃). x 2- →S x-1 2- +S x+1 2- ), and irreversibly generate electrochemically inert sulfate ions (SO4). 2- Byproducts such as [missing information] are produced. This is not only one of the main causes of capacity decay, but also deteriorates the overall chemical environment of the battery. At the same time, the zinc anode itself suffers from problems such as dendrite growth and hydrogen evolution due to corrosion. Meanwhile, the shuttle products polysulfides from the cathode form an insulating and uneven interface layer on the surface of the zinc anode, which drastically exacerbates the unevenness of zinc deposition and becomes a key external factor inducing dendrite growth and accelerating battery failure.

[0004] To address these challenges, existing technologies mostly employ single or partial improvement strategies. For example, carbon materials are combined with sulfur to improve conductivity and buffer volume expansion, but this results in weak chemisorption of polysulfides and fails to inhibit their dissolution and disproportionation in aqueous systems. Polar metal compounds are introduced as adsorbents or catalysts, but these are usually present in a simple mixture, leading to easy aggregation of catalytic sites and low utilization rates, making it difficult to construct efficient charge transport networks. Furthermore, most studies have not focused on blocking the side reaction pathway of disproportionation to sulfate formation. Research on zinc anodes has largely focused on their interface modification, failing to systematically eliminate the "shuttle" polysulfides, a pollution source leading to anode deterioration.

[0005] To address the aforementioned issues, existing technologies primarily focus on improvements in two directions: First, constructing carbon-based composite materials, such as encapsulating sulfur in microporous / mesoporous carbon, carbon nanotubes, or graphene, aims to utilize the high conductivity of carbon materials and their porous structure to physically confine polysulfides. However, traditional carbon materials primarily rely on physical adsorption for polysulfides, resulting in weak interactions that are insufficient to effectively suppress their dissolution in aqueous electrolytes and subsequent chemical disproportionation reactions. Furthermore, their relatively rigid structure often exhibits insufficient adaptability to the significant volume changes of sulfur over long periods, leading to structural fatigue and fracture. Second, introducing polar catalytic materials, such as metal oxides (MnO2, Co3O4), sulfides (CoS2, Ni3S2), or single-atom sites, attempts to anchor and accelerate the conversion of polysulfides through stronger chemical adsorption and catalysis. However, such catalysts usually exist in the form of nano or micron particles. When they are simply mixed with sulfur and conductive agents to prepare electrodes, they are prone to agglomeration, which leads to a significant reduction in the utilization rate of active sites. More importantly, this simple mechanical mixing method makes it difficult to construct a long-range, continuous and stable high-efficiency electron conduction network, which severely restricts the charge transport capability of the electrode at high rates and cannot synergistically solve multiple requirements such as conductivity, confinement, catalysis and structural stability. Summary of the Invention

[0006] This application provides a self-supporting composite sulfur cathode sheet, its preparation method, and its application, aiming to solve the problems of structural instability, low utilization rate of active materials, large battery polarization, poor rate performance, and short cycle life of existing aqueous zinc-sulfur batteries.

[0007] The first aspect of this application provides a self-supporting composite sulfur positive electrode sheet, comprising a three-dimensional carrier and elemental sulfur filled within the three-dimensional carrier;

[0008] The three-dimensional carrier includes a three-dimensional conductive framework material and metal nanomaterials loaded on the three-dimensional conductive framework material; The amount of elemental sulfur is 2-9 times the mass of the three-dimensional carrier.

[0009] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the three-dimensional conductive framework material includes three-dimensional foam metal and / or three-dimensional carbon-based material.

[0010] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the metal nanomaterial includes metal nanoparticles and / or metal nanoflowers; preferably, the metal nanomaterial includes metal nanoparticles and metal nanoflowers in a molar ratio of 1:(1-10).

[0011] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the three-dimensional foam metal includes foamed nickel and / or foamed copper; the three-dimensional carbon-based material includes one or more of carbonized cellulose, graphene foam, carbon nanotube sponge, carbon fiber cloth, and biocarbon materials.

[0012] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the metal nanoparticles include platinum nanoparticles and / or palladium nanoparticles.

[0013] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the metal nanoflowers include one or more of manganese dioxide nanoflowers, vanadium pentoxide nanoflowers, and cobalt sulfide nanoflowers.

[0014] According to some embodiments of the self-supporting composite sulfur cathode sheet described in this application, the loading of metal nanomaterials in the three-dimensional carrier is 5%-50% of the mass of the three-dimensional conductive framework material.

[0015] A second aspect of this application provides a method for preparing the self-supporting composite sulfur positive electrode sheet described in the first aspect of this application, comprising the following steps: (1) Preparation of three-dimensional carriers; A three-dimensional conductive framework material was mixed with a solution containing a first metal compound and a reducing agent, and a hydrothermal reaction was carried out to obtain a three-dimensional carrier loaded with metal nanoflowers. And / or, the three-dimensional support loaded with metal nanoflowers is mixed with a solution containing a second metal compound and methanol, and then irradiated with ultraviolet light to obtain a three-dimensional support loaded with metal nanoflowers and / or metal nanoparticles. (2) The three-dimensional carrier and sulfur powder are mixed and heated to obtain the self-supporting composite sulfur positive electrode sheet.

[0016] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (1), the first metal compound includes one or more of potassium permanganate (KMnO4), ammonium metavanadate (NH4VO3), cobalt chloride (CoCl2), cobalt nitrate (Co(NO3)2) and manganese sulfate (MnSO4).

[0017] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, the reducing agent includes one or more of urea, glucose, ascorbic acid, sodium citrate, and sodium thiosulfate.

[0018] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (1), the molar concentration of the first metal compound in the solution is 0.01-0.5 mol / L.

[0019] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (1), the molar concentration of the reducing agent in the solution is 0.05-2 mol / L.

[0020] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (1), the temperature of the hydrothermal reaction is 100-200℃ and the time is 4-24h.

[0021] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (1), the second metal compound includes one or more of chloroplatinic acid (H2PtCl6), chloropalladic acid (H2PdCl4), silver nitrate (AgNO3) and chloroauric acid (HAuCl4).

[0022] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, the molar concentration of the second metal compound in the solution is 0.5-20 mmol / L.

[0023] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, the molar concentration of methanol in the solution is 0.05-1 mol / L.

[0024] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, the wavelength of the ultraviolet irradiation is 200-365nm and the irradiation time is 10-120min.

[0025] According to some embodiments of the preparation method of the self-supporting composite sulfur positive electrode sheet described in this application, in step (2), the temperature of the mixing and heating is 140-180℃ and the time is 6-24h.

[0026] A third aspect of this application provides a water-based zinc battery, including the self-supporting composite sulfur positive electrode sheet described in the first aspect of this application or the self-supporting composite sulfur positive electrode sheet obtained by the preparation method described in the second aspect of this application.

[0027] The beneficial effects of this application include: the three-dimensional conductive framework material contained in the three-dimensional carrier of the self-supporting composite sulfur cathode sheet described in this application, together with the metal nanomaterials, provides a continuous conductive network and a fast ion transport channel, which enables more sulfur to participate in the effective reaction, and makes the water-based zinc battery exhibit excellent rate performance and cycle stability.

[0028] The metal nanomaterials contained in the self-supporting composite sulfur cathode sheet described in this application can guide the conversion of polysulfides to ZnS through a chemical pathway, significantly inhibit sulfate generation, effectively suppress polysulfide shuttle and side reactions, and improve the coulombic efficiency of water-based zinc batteries.

[0029] The self-supporting composite sulfur cathode described in this application significantly reduces the amount of active material shuttling to the anode due to the efficient anchoring and conversion of polysulfides on the cathode side, thus avoiding zinc anode surface corrosion and interface inhomogeneity caused by polysulfide reduction reactions. Simultaneously, some metal nanomaterials (such as trace amounts of Mn from MnO2)... 2+ It may form a uniform and dense interface protective layer on the surface of the zinc anode, guiding the uniform deposition of zinc ions and significantly improving the dendrite morphology on the surface of the zinc anode. Attached Figure Description

[0030] Figure 1 SEM image of the CBC@(Pt / MnO2) cathode material prepared in Example 1 of this application; Figure 2 This is a TEM image of the CBC@(Pt / MnO2) cathode material prepared in Example 1 of this application. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] This application provides a self-supporting composite sulfur positive electrode sheet, comprising a three-dimensional carrier and elemental sulfur filled within the three-dimensional carrier; The three-dimensional carrier includes a three-dimensional conductive framework material and metal nanomaterials loaded on the three-dimensional conductive framework material; The amount of elemental sulfur is 2-9 times the mass of the three-dimensional carrier.

[0034] The three-dimensional conductive framework material contained in the three-dimensional carrier of the self-supporting composite sulfur cathode described in this application, together with the metal nanomaterials, provides a continuous conductive network and a fast ion transport channel, which enables more sulfur to participate in the effective reaction, thus enabling the water-based zinc battery to exhibit excellent rate performance and cycle stability.

[0035] The metal nanomaterials contained in the self-supporting composite sulfur cathode sheet described in this application can guide the conversion of polysulfides to ZnS through a chemical pathway, significantly inhibit sulfate generation, effectively suppress polysulfide shuttle and side reactions, and improve the coulombic efficiency of water-based zinc batteries.

[0036] The self-supporting composite sulfur cathode described in this application significantly reduces the amount of active material shuttling to the anode due to the efficient anchoring and conversion of polysulfides on the cathode side, thus avoiding zinc anode surface corrosion and interface inhomogeneity caused by polysulfide reduction reactions. Simultaneously, some metal nanomaterials (such as trace amounts of Mn from MnO2)... 2+ It may form a uniform and dense interface protective layer on the surface of the zinc anode, guiding the uniform deposition of zinc ions and significantly improving the dendrite morphology on the surface of the zinc anode.

[0037] In some embodiments of this application, the three-dimensional conductive framework material includes three-dimensional foamed metal and / or three-dimensional carbon-based materials; the three-dimensional conductive framework material is the macroscopic support and main conductive pathway of the self-supporting composite sulfur cathode sheet. It possesses high porosity (porosity > 90%) and interconnected hierarchical channels (macropores: tens of micrometers; mesopores and micropores: several nanometers to hundreds of nanometers) providing ample space for sulfur loading, electrolyte wetting, and ion transport. The three-dimensional conductive framework material has good mechanical strength and a certain degree of elasticity, capable of buffering the volume expansion / contraction stress of sulfur during charging and discharging like a "spring mattress," preventing damage to the overall electrode structure; and it has high electronic conductivity, providing a rapid electron transport path for electrochemical reactions.

[0038] In some embodiments of this application, the metal nanomaterials include metal nanoparticles and / or metal nanoflowers; preferably, the metal nanomaterials include metal nanoparticles and metal nanoflowers in a molar ratio of 1:(1-10).

[0039] Metal nanomaterials, acting as "multifunctional catalytic sites," are uniformly anchored on the surface of a three-dimensional conductive framework material in a highly dispersed manner. They anchor polysulfides through strong chemical interactions; catalyze and accelerate the liquid-solid conversion reaction of polysulfides, enhancing reaction kinetics; inhibit the irreversible disproportionation reaction of polysulfides to electrochemically inert sulfate and other byproducts through selective catalysis and surface chemistry; fundamentally reduce the diffusion of soluble polysulfides to the negative electrode side, providing a "clean" deposition environment for the zinc negative electrode, thus facilitating the uniform deposition of zinc ions and playing a crucial auxiliary role in inhibiting zinc dendrite growth.

[0040] The composite loading system of metal nanoparticles and metal nanoflowers forms an "adsorption-catalysis" tandem mechanism. The heterogeneous interface can optimize electron transfer, which not only efficiently fixes and transforms polysulfides, but also stabilizes the electrolyte composition and reduces drastic fluctuations in pH and local ion concentration, creating favorable conditions for stable zinc deposition.

[0041] In some embodiments of this application, the size of the metal nanoparticles is 1nm-100nm, such as 1nm, 10nm, 20nm, 30nm, 50nm, 80nm, 100nm, etc. The size of the metal nanoflowers is 100nm-1um, such as 100nm, 200nm, 500nm, 800nm, 1um, etc.

[0042] In some embodiments of this application, the three-dimensional foamed metal includes foamed nickel and / or foamed copper; the three-dimensional carbon-based material includes one or more of carbonized cellulose, graphene foam, carbon nanotube sponge, carbon fiber cloth, and biocarbon materials.

[0043] In some embodiments of this application, the metal nanoparticles include platinum nanoparticles and / or palladium nanoparticles; the high catalytic activity of the noble metal nanoparticles can quickly "digest" polysulfides, greatly reducing their concentration in the electrolyte, cutting off the source of substances that cause zinc anode corrosion and interface deterioration from the source, and indirectly protecting the zinc anode.

[0044] In some embodiments of this application, the metal nanoflowers include one or more of manganese dioxide nanoflowers, vanadium pentoxide nanoflowers, and cobalt sulfide nanoflowers. Transition metal oxide or sulfide catalysts can selectively catalyze polysulfide conversion pathways and inhibit sulfate formation. Trace amounts of Mn... 2+ Co 2+ Controlled dissolution during long-term cycling may form a protective interfacial film with ionic conductivity on the surface of the zinc anode, further guiding the uniform deposition of zinc and directly helping to suppress dendrite formation.

[0045] In some embodiments of this application, the loading amount of metal nanomaterials in the three-dimensional carrier is 5%-50% of the mass of the three-dimensional conductive framework material. When the loading amount of metal nanomaterials is controlled within the range of 5wt% to 50wt%, the catalytic active sites can be highly dispersed and uniformly anchored on the surface of the three-dimensional conductive framework, giving full play to the chemical adsorption and catalytic conversion of polysulfides, while maximizing the preservation of the multi-level pore structure of the three-dimensional carrier, ensuring sufficient electrolyte wetting and rapid zinc ion transport, and synergistically guaranteeing the high rate performance and long cycle stability of the electrode; in addition, this loading range can also effectively avoid the problems of pore blockage or framework embrittlement caused by excessive accumulation of metal nanomaterials, so that the electrode can still maintain structural stability under sulfur charge-discharge volume changes, significantly extending the battery life.

[0046] This application also provides a method for preparing the self-supporting composite sulfur positive electrode sheet described in the first aspect of this application, comprising the following steps: (1) Preparation of three-dimensional carriers; A three-dimensional conductive framework material was mixed with a solution containing a first metal compound and a reducing agent, and a hydrothermal reaction was carried out to obtain a three-dimensional carrier loaded with metal nanoflowers. And / or, the three-dimensional support loaded with metal nanoflowers is mixed with a solution containing a second metal compound and methanol, and then irradiated with ultraviolet light to obtain a three-dimensional support loaded with metal nanoflowers and / or metal nanoparticles. (2) The three-dimensional carrier and sulfur powder are mixed and heated to obtain the self-supporting composite sulfur positive electrode. Elemental sulfur can also be uniformly filled into the pores of the three-dimensional conductive framework loaded with catalytic nanomaterials by vapor deposition or solution method, and in close contact with the catalytic nanomaterials.

[0047] In some embodiments of this application, in step (1), the first metal compound includes one or more of potassium permanganate (KMnO4), ammonium metavanadate (NH4VO3), cobalt chloride (CoCl2), cobalt nitrate (Co(NO3)2), and manganese sulfate (MnSO4).

[0048] In some embodiments of this application, the reducing agent includes one or more of urea, glucose, ascorbic acid, sodium citrate, and sodium thiosulfate.

[0049] In some embodiments of this application, in step (1), the molar concentration of the first metal compound in the solution is 0.01-0.5 mol / L; for example, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.18 mol / L, 0.25 mol / L, 0.38 mol / L, 0.5 mol / L, etc. The solvent used in the solutions of this application embodiments may be one or more of deionized water, aqueous ethanol solution, or a mixture of deionized water and ethanol; preferably, the solvent is deionized water.

[0050] In some embodiments of this application, in step (1), the molar concentration of the reducing agent in the solution is 0.05-2 mol / L; for example, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 2 mol / L, etc.

[0051] In some embodiments of this application, in step (1), the temperature of the hydrothermal reaction is 100-200℃, for example 100℃, 120℃, 150℃, 180℃, 200℃, etc., and the time is 4-24h, for example 4h, 8h, 12h, 16h, 20h, 24h, etc.

[0052] In some embodiments of this application, in step (1), the second metal compound includes one or more of chloroplatinic acid (H2PtCl6), chloropalladic acid (H2PdCl4), silver nitrate (AgNO3), and chloroauric acid (HAuCl4).

[0053] In some embodiments of this application, the molar concentration of the second metal compound in the solution is 0.5-20 mmol / L; for example, 0.5 mmol / L, 1.0 mmol / L, 5 mmol / L, 8.9 mmol / L, 12.5 mmol / L, 13.8 mmol / L, 20 mmol / L, etc.

[0054] In some embodiments of this application, the molar concentration of methanol in the solution is 0.05-1 mol / L; for example, 0.05 mol / L, 0.08 mol / L, 0.15 mol / L, 0.38 mol / L, 0.65 mol / L, 1 mol / L, etc.

[0055] In some embodiments of this application, the wavelength of the ultraviolet irradiation is 200-365nm, and the irradiation time is 10-120min.

[0056] In some embodiments of this application, in step (2), the temperature of the mixed heating is 140-180℃, such as 140℃, 150℃, 160℃, 168℃, 180℃, etc., and the time is 6-24h; such as 6h, 8h, 12h, 20h, 24h, etc.

[0057] In some embodiments of this application, the method for preparing the self-supporting composite sulfur positive electrode sheet includes the following steps: Pure bacterial cellulose (BC) hydrogel prepared by biological culture was washed with deionized water until neutral and then freeze-dried to obtain BC aerogel with a natural three-dimensional nanofiber network structure. The BC aerogel was placed in a tube furnace and heated to 900℃ at a rate of 5℃ / min under argon protection, and carbonized at this temperature for 2 hours. After natural cooling, a carbonized bacterial cellulose (CBC) three-dimensional network framework was obtained. This framework inherits the original three-dimensional interconnected nanofiber network of bacterial cellulose and exhibits good electrical conductivity, excellent mechanical flexibility, and high porosity after carbonization. Before use, the CBC framework was ultrasonically cleaned in ethanol and deionized water for 15 minutes each to enhance its surface wettability, and then dried for later use.

[0058] Pretreated carbonized bacterial cellulose (CBC) three-dimensional network frameworks were immersed in an aqueous solution containing 0.05 mol / L KMnO4 and 0.15 mol / L urea (as reducing agent and defect inducer). The reaction was carried out hydrothermally at 120 °C for 8 h. During this process, KMnO4 was reduced on the surface of the CBC nanofibers, uniformly growing nanoflowers composed of oxygen-vacancy-rich MnO2 nanosheets, which were firmly anchored within the carbon fibers, forming CBC@MnO2 intermediates. The nanofibers were then removed, washed, and dried.

[0059] The above CBC@MnO2 intermediate was immersed in an aqueous solution containing 2 mmol / L H2PtCl6 and 0.1 mol / L methanol, and then irradiated with ultraviolet light (wavelength 254 nm) for 30 min. Pt 2+ Defect sites on the MnO2 surface and adjacent carbon fiber surfaces are in-situ reduced to Pt nanoparticles, thus forming a strongly electron-interacting CBC@(Pt / MnO2) composite three-dimensional support material. This heterogeneous interface can efficiently catalyze the conversion of polysulfides, while the carbon fiber network provides additional fast electron pathways.

[0060] Sublimated sulfur powder and the above-mentioned CBC@(Pt / MnO2) three-dimensional support material were ground and mixed evenly at a mass ratio (sulfur:sulfur support = 7:3) and placed in an argon-filled glove box. The mixture was then transferred to a sealed reactor and heated at 155°C for 12 hours, allowing the molten sulfur to fully penetrate into the nanofiber network of the CBC framework and the composite pores formed by the catalytic material through capillary action. After natural cooling to room temperature, the final self-supporting composite sulfur cathode material (CBC@(Pt / MnO2)@S) was obtained.

[0061] In the above embodiments, MnO2 nanoflowers are grown in situ on the surface of flexible CBC carbon fibers via hydrothermal methods, followed by Pt nanoparticles loaded via photodeposition. This multi-step in-situ method ensures a tight physical bond and potential chemical bond between the catalytic component and the carbon framework, preventing detachment during cycling. The resulting "CBC-MnO2-Pt" hierarchical heterostructure synergistically integrates electrical conductivity, adsorption, and catalytic functions.

[0062] Because the mechanical strength of the three-dimensional conductive framework material is sufficient to support the active material, the final material can be directly used as a self-supporting electrode without binders or additional current collectors, simplifying the process and improving the overall energy density of the electrode.

[0063] This application also provides an aqueous zinc battery, comprising the self-supporting composite sulfur positive electrode sheet described in the first aspect of this application or the self-supporting composite sulfur positive electrode sheet obtained by the preparation method described in the second aspect of this application. The aqueous zinc battery described in this application exhibits excellent rate performance and cycle stability, and significantly inhibits the growth of zinc anode dendrites.

[0064] The technical solution of this application will be further described below with reference to specific embodiments.

[0065] Example 1 A method for preparing a self-supporting composite sulfur positive electrode sheet includes the following steps: (1) 0.1 g of three-dimensional carbon-based material (carbonized bacterial cellulose CBC) was immersed in 50 mL of an aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 was 0.05 mol / L and the molar concentration of urea was 0.15 mol / L). The solution was subjected to hydrothermal reaction at 120 °C for 8 h, so that KMnO4 was reduced on the surface of the three-dimensional carbon-based material, and nanoflowers composed of MnO2 nanosheets rich in oxygen vacancies were uniformly grown (e.g., Figure 1 As shown in the figure, the MnO2 is firmly anchored inside the carbon fiber to form a CBC@MnO2 intermediate, which is then removed, washed, and dried. The loading of MnO2 in this step is approximately 20 wt% of the mass of the CBC.

[0066] (2) The above CBC@MnO2 intermediate was immersed in 50 mL of an aqueous solution containing H2PtCl6 and methanol (wherein the molar concentration of H2PtCl6 was 2 mmol / L and the molar concentration of methanol was 0.1 mol / L), and irradiated with ultraviolet light at a wavelength of 254 nm for 30 min. This allowed the Pt... 2+ At defect sites on the MnO2 surface and on the adjacent carbon fiber surface, Pt nanoparticles are in situ reduced to Pt nanoparticles (e.g., ...). Figure 2As shown in the figure, a strongly electron-interacting CBC@(Pt / MnO2) composite three-dimensional support is formed. In this step, the loading of Pt is approximately 5 wt% of the mass of CBC, and the total loading of metal nanomaterials (Pt nanoparticles + MnO2 nanoflowers) is approximately 25 wt% of the mass of CBC, wherein the mass ratio of Pt nanoparticles to MnO2 nanoflowers is approximately 1:4.

[0067] (3) Sublimed sulfur powder with a mass ratio of 7:3 was ground and mixed with the above-mentioned CBC@(Pt / MnO2) three-dimensional support. The mixture was then transferred to a sealed reactor and heated at 155°C for 12 hours to allow the molten sulfur to fully penetrate into the nanofiber network of the three-dimensional support and the composite pores formed by the catalytic material through capillary action. After natural cooling to room temperature, the final self-supporting composite sulfur positive electrode (CBC@(Pt / MnO2)@S) was obtained.

[0068] Example 2 The only difference between the preparation method of the self-supporting composite sulfur cathode sheet in Example 2 and that in Example 1 is that the loading amount of metal nanomaterials in the three-dimensional carrier during the preparation of the self-supporting composite sulfur cathode sheet in Example 2 is 12.5 wt% of the mass of the three-dimensional conductive framework material.

[0069] The specific operating steps include: (1) Immerse 0.1g of three-dimensional carbon-based material in 50mL of aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 is 0.025mol / L and the molar concentration of urea is 0.075mol / L), and perform hydrothermal reaction at 120℃ for 8h to reduce KMnO4 on the surface of the three-dimensional carbon-based material and uniformly grow nanoflowers composed of MnO2 nanosheets rich in oxygen vacancies, which are firmly anchored inside the carbon fiber to form CBC@MnO2 intermediate (MnO2 loading is about 10wt% of the mass of CBC), and then take it out, wash and dry it.

[0070] (2) Immerse the above CBC@MnO2 intermediate in 50 mL of an aqueous solution containing H2PtCl6 and methanol (wherein the molar concentration of H2PtCl6 is 1 mmol / L and the molar concentration of methanol is 0.1 mol / L), and irradiate with ultraviolet light at a wavelength of 254 nm for 30 min. This allows the Pt... 2+ Defect sites on the MnO2 surface and adjacent carbon fiber surfaces are in-situ reduced to Pt nanoparticles, thereby forming a strongly electron-interacting CBC@(Pt / MnO2) composite three-dimensional support. In this step, the Pt loading is approximately 2.5 wt% of the CBC mass, and the total loading of metal nanomaterials is approximately 12.5 wt% of the CBC mass; the mass ratio of Pt nanoparticles to MnO2 nanoflowers is approximately 1:4. The operation steps are the same as in Example 1.

[0071] Example 3 The only difference between the preparation method of the self-supporting composite sulfur cathode sheet in Example 3 and that in Example 1 is that the loading amount of metal nanomaterials in the three-dimensional carrier during the preparation of the self-supporting composite sulfur cathode sheet in Example 3 is 35 wt% of the mass of the three-dimensional conductive framework material.

[0072] The specific operating steps include: (1) Immerse 0.1g of three-dimensional carbon-based material in 50mL of aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 is 0.10mol / L and the molar concentration of urea is 0.30mol / L), and perform hydrothermal reaction at 120℃ for 8h to reduce KMnO4 on the surface of the three-dimensional carbon-based material and uniformly grow nanoflowers composed of MnO2 nanosheets rich in oxygen vacancies, which are firmly anchored inside the carbon fiber to form CBC@MnO2 intermediate (MnO2 loading is about 28wt% of the mass of CBC), and then take it out, wash and dry it.

[0073] It should be noted that although the molar concentration of KMnO4 in this embodiment (0.10 mol / L) increased by 2 times compared to Example 1 (0.05 mol / L), the actual loading of MnO2 did not increase proportionally. This is because when the amount of KMnO4 increases, the active sites on the CBC surface available for MnO2 nucleation tend to become saturated. Excess KMnO4 is reduced in solution but cannot be effectively anchored to the carbon fiber surface, resulting in a decrease in deposition efficiency with increasing precursor concentration. Examples are provided below.

[0074] (2) Immerse the above CBC@MnO2 intermediate in 50 mL of an aqueous solution containing H2PtCl6 and methanol (wherein the molar concentration of H2PtCl6 is 3 mmol / L and the molar concentration of methanol is 0.1 mol / L), and irradiate with ultraviolet light at a wavelength of 254 nm for 30 min. 2+ The defect sites on the MnO2 surface and the adjacent carbon fiber surface are in situ reduced to Pt nanoparticles, thereby forming a CBC@(Pt / MnO2) composite three-dimensional carrier with strong electronic interactions. In this step, the loading of Pt is about 7 wt% of the mass of CBC, and the total loading of metal nanomaterials is about 35 wt% of the mass of CBC. The mass ratio of Pt nanoparticles to MnO2 nanoflowers is about 1:4. The operation steps are the same as in Example 1.

[0075] Example 4 The only difference between the preparation method of the self-supporting composite sulfur cathode sheet in Example 4 and that in Example 1 is that the loading amount of metal nanomaterials in the three-dimensional carrier during the preparation of the self-supporting composite sulfur cathode sheet in Example 4 is 50 wt% of the mass of the three-dimensional conductive framework material.

[0076] The specific operating steps include: (1) Immerse 0.1g of three-dimensional carbon-based material in 50mL of aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 is 0.15mol / L and the molar concentration of urea is 0.45mol / L), and perform hydrothermal reaction at 120℃ for 8h to reduce KMnO4 on the surface of the three-dimensional carbon-based material and uniformly grow nanoflowers composed of MnO2 nanosheets rich in oxygen vacancies, which are firmly anchored inside the carbon fiber to form CBC@MnO2 intermediate (MnO2 loading is about 40wt% of the mass of CBC), and then take it out, wash and dry it.

[0077] (2) Immerse the above CBC@MnO2 intermediate in 50 mL of an aqueous solution containing H2PtCl6 and methanol (wherein the molar concentration of H2PtCl6 is 4 mmol / L and the molar concentration of methanol is 0.1 mol / L), and irradiate with ultraviolet light at a wavelength of 254 nm for 30 min. 2+ The defect sites on the MnO2 surface and the adjacent carbon fiber surface are in situ reduced to Pt nanoparticles, thereby forming a CBC@(Pt / MnO2) composite three-dimensional carrier with strong electronic interactions. In this step, the loading of Pt is about 10 wt% of the mass of CBC, and the total loading of metal nanomaterials is about 50 wt% of the mass of CBC. The mass ratio of Pt nanoparticles to MnO2 nanoflowers is about 1:4. The operation steps are the same as in Example 1.

[0078] Example 5 The difference between the preparation method of the self-supporting composite sulfur cathode sheet in Example 5 and that in Example 1 is that the metal nanomaterials in the preparation process of the self-supporting composite sulfur cathode sheet in Example 5 include metal nanoparticles (Pt nanoparticles) and metal nanoflowers (MnO2 nanoflowers) with a mass ratio of 1:2, and the total loading of metal nanomaterials is maintained at about 25 wt% of the mass of CBC.

[0079] Specifically, in step (1), 0.1 g of three-dimensional carbon-based material is immersed in 50 mL of an aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 is 0.038 mol / L and the molar concentration of urea is 0.114 mol / L), and hydrothermally reacted at 120 °C for 8 h to form a CBC@MnO2 intermediate (the MnO2 loading is approximately 16.7 wt% of the CBC mass). In step (2), the above CBC@MnO2 intermediate was immersed in 50 mL of an aqueous solution containing H2PtCl6 and methanol (where the molar concentration of H2PtCl6 was 3.5 mmol / L and the molar concentration of methanol was 0.1 mol / L), and irradiated with ultraviolet light at a wavelength of 254 nm for 30 min, so that the loading of Pt was about 8.3 wt% of the mass of CBC, the total loading of metal nanomaterials was about 25 wt% of the mass of CBC, and the final mass ratio of Pt nanoparticles to MnO2 nanoflowers was about 1:2; the remaining steps were the same as in Example 1.

[0080] Example 6 The difference between the preparation method of the self-supporting composite sulfur cathode sheet described in Example 6 and that in Example 1 is that the metal nanomaterials in the preparation process of the self-supporting composite sulfur cathode sheet described in Example 6 include metal nanoparticles (Pt nanoparticles) and metal nanoflowers (MnO2 nanoflowers) with a mass ratio of 1:8, and the total loading of metal nanomaterials is maintained at approximately 25 wt% of the mass of CBC.

[0081] 0.1 g of three-dimensional carbon-based material was immersed in 50 mL of an aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 was 0.06 mol / L and the molar concentration of urea was 0.18 mol / L), and hydrothermally reacted at 120 °C for 8 h to form a CBC@MnO2 intermediate (the MnO2 loading was approximately 22.2 wt% of the CBC mass). In step (2), the above CBC@MnO2 intermediate was immersed in 50 mL of an aqueous solution containing H2PtCl6 and methanol (where the molar concentration of H2PtCl6 was 1.13 mmol / L and the molar concentration of methanol was 0.1 mol / L), and irradiated with ultraviolet light at a wavelength of 254 nm for 30 min, so that the Pt loading was approximately 2.8 wt% of the CBC mass, the total loading of metal nanomaterials was approximately 25 wt% of the CBC mass, and the final mass ratio of Pt nanoparticles to MnO2 nanoflowers was approximately 1:8. The remaining steps were the same as in Example 1.

[0082] Example 7 The difference between the preparation method of the self-supporting composite sulfur cathode sheet in Example 7 and that in Example 1 is that the metal nanomaterials in the preparation process of the self-supporting composite sulfur cathode sheet in Example 7 include metal nanoparticles (Pt nanoparticles) and metal nanoflowers (MnO2 nanoflowers) with a molar ratio of 1:10, and the total loading of metal nanomaterials is maintained at about 25 wt% of the CBC mass.

[0083] Specifically, in step (1), 0.1 g of three-dimensional carbon-based material was immersed in 58 mL of an aqueous solution containing KMnO4 and urea (where the molar concentration of KMnO4 was 0.065 mol / L and the molar concentration of urea was 0.195 mol / L), and hydrothermally reacted at 120 °C for 8 h to form a CBC@MnO2 intermediate (the MnO2 loading was approximately 23 wt% of the CBC mass); in step (2), the above CBC@MnO2 intermediate was immersed in 50 mL of an aqueous solution containing H2PtCl6 and methanol (where the molar concentration of H2PtCl6 was 0.92 mmol / L and the molar concentration of methanol was 0.1 mol / L), and irradiated with ultraviolet light at a wavelength of 254 nm for 30 min, so that the Pt loading was approximately 2.3 wt% of the CBC mass, the total loading of metal nanomaterials was approximately 25 wt% of the CBC mass, and the final mass ratio of Pt nanoparticles to MnO2 nanoflowers was approximately 1:10; the remaining steps were the same as in Example 1.

[0084] Example 8 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet described in Example 8 and that in Example 1, the hydrothermal reaction temperature of the three-dimensional conductive framework material mixed with a solution containing a first metal compound and a reducing agent during the preparation process of the self-supporting composite sulfur positive electrode sheet in Example 8 is 100°C.

[0085] Example 9 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet in Example 9 and that in Example 1, the temperature at which the three-dimensional conductive framework material is mixed with a solution containing a first metal compound and a reducing agent for hydrothermal reaction is 150°C.

[0086] Example 10 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet described in Example 10 and Example 1 is that the hydrothermal reaction temperature during the preparation of the self-supporting composite sulfur positive electrode sheet described in Example 10 is 180°C, in which the three-dimensional conductive framework material is mixed with a solution containing a first metal compound and a reducing agent.

[0087] Example 11 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet described in Example 11 and Example 1 is that the mass ratio of the three-dimensional carrier and sulfur powder is adjusted to 1:4 during the preparation process of the self-supporting composite sulfur positive electrode sheet described in Example 11 (i.e., the amount of elemental sulfur is 400wt% of the mass of the three-dimensional carrier).

[0088] Example 12 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet described in Example 12 and that in Example 1, the mass ratio of the three-dimensional carrier and sulfur powder is adjusted to 1:6 (i.e., the amount of elemental sulfur is 600wt% of the mass of the three-dimensional carrier) during the preparation process of the self-supporting composite sulfur positive electrode sheet described in Example 12.

[0089] Example 13 The only difference between the preparation method of the self-supporting composite sulfur positive electrode sheet described in Example 13 and Example 1 is that the mass ratio of the three-dimensional carrier and sulfur powder is adjusted to 1:9 during the preparation process of the self-supporting composite sulfur positive electrode sheet described in Example 13 (i.e., the amount of elemental sulfur is 900wt% of the mass of the three-dimensional carrier).

[0090] Performance Study of the Self-Supported Composite Sulfur Positive Electrode Sheet Described in Examples 1-13 of this Application Research Methods: The self-supporting composite sulfur cathode materials prepared in Examples 1-13 were cut into circular pieces with a diameter of 12 mm, without the addition of any conductive agent or binder, and without the need for additional current collectors.

[0091] Negative electrode sheet: The negative electrode sheet is made of zinc foil with a thickness of 0.1mm. After being cut into round sheets with a diameter of 14mm, it is cleaned by wiping with dilute hydrochloric acid, deionized water and ethanol in turn to remove the surface oxide layer, and then dried for later use.

[0092] Diaphragm: The diaphragm is made of glass fiber that is stable to aqueous electrolytes and can effectively block zinc dendrites. It is cut into round pieces with a diameter of 16mm for later use.

[0093] Electrolyte: The basic electrolyte is a 2M zinc trifluoromethanesulfonate aqueous solution. Sodium sulfate is added as a pH buffer to stabilize the chemical environment of the electrolyte (0.1M sodium sulfate is added to the electrolyte), and manganese sulfate is added as a negative electrode interface conditioner (0.05M manganese sulfate is added to the electrolyte). The prepared electrolyte needs to stand for 24 hours before use.

[0094] Battery Assembly: Battery assembly was strictly performed in an argon-filled glove box. First, the negative electrode shell was placed, followed by the prepared zinc foil negative electrode. 80 μL of electrolyte was added on top, and then a separator already impregnated with electrolyte was laid on top. Next, 60 μL of electrolyte was added to the separator, followed by careful placement of the self-supporting composite sulfur positive electrode sheet, ensuring full contact. Finally, the gasket, spring clip, and positive electrode shell were sequentially placed on top, and the battery was sealed using a coin cell sealing machine under 6 MPa pressure, ensuring complete air isolation from the battery interior. The sealed batteries were allowed to stand at room temperature for 8 hours to allow for full electrolyte impregnation, followed by electrochemical testing. The test results are shown in Table 1.

[0095] Table 1. Electrochemical performance of the self-supporting composite sulfur cathode sheets prepared in Examples 1-13

[0096] As can be seen from Table 1: (1) Comparing Examples 1-4, it can be seen that the battery's overall performance is optimal when the metal nanomaterial loading is between 25wt% and 35wt%. Example 1 (25wt%) has an initial discharge specific capacity of 1312 mAh g⁻¹. -1 The first example achieved the highest capacity retention (84.7%) after 200 cycles; Example 2 (10wt%) had an insufficient loading, resulting in inadequate conductive network and catalytic sites, leading to a low initial discharge specific capacity (1056 mAh g⁻¹). -1 Both the catalytic sites and cycle stability (67.0%) of Example 4 (50wt%) decreased significantly. Although the number of catalytic sites increased, the excessive loading caused partial blockage of the three-dimensional framework pores, which hindered ion transport. The performance was lower than that of Example 3 and Example 1. This shows that there is an optimal range for the loading of metal nanomaterials. Too high or too low loading is not conducive to maximizing battery performance.

[0097] (2) Comparing Examples 1 and 5-7, it can be seen that the battery exhibits optimal overall performance when the Pt:MnO2 molar ratio is 1:4. When the molar ratio is 1:2 (Example 5), the Pt content is relatively high, resulting in strong catalytic activity, but the chemisorption of polysulfides by the MnO2 nanoflowers is weakened, leading to a decrease in synergistic effect. When the molar ratio is 1:10 (Example 7), excessive MnO2 leads to relatively dispersed Pt catalytic sites, reducing the synergistic adsorption-catalysis efficiency. These results indicate that there is an optimal molar ratio between Pt nanoparticles and MnO2 nanoflowers, and their synergistic effect reaches its best balance at around 1:4.

[0098] (3) Comparing Examples 1 and 8-10, it can be seen that when the hydrothermal temperature is 150℃ (Example 9), the MnO2 nanoflower morphology is the most complete and the dispersion is the best, and the first discharge specific capacity of the obtained electrode is 1331 mAh g. -1 The electrochemical performance was better at 120℃ (Example 1) and 180℃ (Example 10) than at 100℃ (Example 8), with insufficient reaction kinetics, poor crystallinity of MnO2 nanoflowers, low loading, and the worst electrochemical performance. At 180℃, local aggregation of MnO2 nanoflowers occurred, the utilization rate of active sites decreased, and the performance was slightly lower than at 150℃. Considering all factors, a hydrothermal temperature of 120℃ to 150℃ is preferable.

[0099] (4) Comparing Examples 1 and 11-13, it can be seen that the initial discharge specific capacity first increases and then decreases with the increase of sulfur content. The initial discharge specific capacity is highest when the sulfur content is 600 wt% (Example 12) (1423 mAh g). -1This indicates that appropriately increasing the sulfur loading can improve the utilization rate of active materials; however, when the sulfur loading increases to 900 wt% (Example 13), excessive sulfur leads to severe blockage of electrode pores, obstruction of ion transport paths, and a decrease in conductivity. The capacity retention rate after 200 cycles drops to 68.3%, and the coulombic efficiency also drops to 93.1%, indicating a significant deterioration in cycle stability. Therefore, the optimal range for sulfur loading is 200 wt% to 600 wt%, which ensures both high active material loading and structural stability and ion transport efficiency.

[0100] In summary, the self-supporting composite sulfur cathode described in this application exhibits the best overall electrochemical performance under the conditions of a metal nanomaterial loading of 25wt% to 35wt%, a Pt:MnO2 mass ratio of 1:4, a hydrothermal temperature of 120℃ to 150℃, and a sulfur filling amount of 233wt% to 600wt%. This verifies the effectiveness of the synergistic effect between the three-dimensional conductive framework and the Pt / MnO2 nanocatalytic material, as well as the significant contribution of the self-supporting structure design to the performance improvement of water-based zinc-sulfur batteries.

[0101] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A self-supporting composite sulfur positive electrode, characterized in that, Includes a three-dimensional carrier and elemental sulfur filled within the three-dimensional carrier; The three-dimensional carrier includes a three-dimensional conductive framework material and metal nanomaterials loaded on the three-dimensional conductive framework material; The amount of elemental sulfur is 2-9 times the mass of the three-dimensional carrier.

2. The self-supporting composite sulfur positive electrode sheet according to claim 1, characterized in that, The three-dimensional conductive framework material includes three-dimensional foamed metal and / or three-dimensional carbon-based materials; And / or, the metal nanomaterials include metal nanoparticles and / or metal nanoflowers; preferably, the metal nanomaterials include metal nanoparticles and metal nanoflowers in a molar ratio of 1:(1-10).

3. The self-supporting composite sulfur positive electrode sheet according to claim 2, characterized in that, The three-dimensional foamed metal includes foamed nickel and / or foamed copper; the three-dimensional carbon-based material includes one or more of carbonized cellulose, graphene foam, carbon nanotube sponge, carbon fiber cloth, and biocarbon materials; And / or, the metal nanoparticles include platinum nanoparticles and / or palladium nanoparticles; And / or, the metal nanoflowers include one or more of manganese dioxide nanoflowers, vanadium pentoxide nanoflowers, and cobalt sulfide nanoflowers.

4. The self-supporting composite sulfur positive electrode sheet according to claim 1, characterized in that, The loading of metal nanomaterials in the three-dimensional carrier is 5%-50% of the mass of the three-dimensional conductive framework material.

5. The method for preparing the self-supporting composite sulfur positive electrode sheet according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of three-dimensional carriers; A three-dimensional conductive framework material was mixed with a solution containing a first metal compound and a reducing agent, and a hydrothermal reaction was carried out to obtain a three-dimensional carrier loaded with metal nanoflowers. And / or, the three-dimensional support loaded with metal nanoflowers is mixed with a solution containing a second metal compound and methanol, and then irradiated with ultraviolet light to obtain a three-dimensional support loaded with metal nanoflowers and / or metal nanoparticles. (2) The three-dimensional carrier and sulfur powder are mixed and heated to obtain the self-supporting composite sulfur positive electrode sheet.

6. The method for preparing the self-supporting composite sulfur positive electrode sheet according to claim 5, characterized in that, In step (1), the first metal compound includes one or more of potassium permanganate, ammonium metavanadate, cobalt chloride, cobalt nitrate, and manganese sulfate; And / or, the reducing agent includes one or more of urea, glucose, ascorbic acid, sodium citrate and sodium thiosulfate; And / or, in step (1), the molar concentration of the first metal compound in the solution is 0.01-0.5 mol / L; And / or, in step (1), the molar concentration of the reducing agent in the solution is 0.05-2 mol / L.

7. The method for preparing the self-supporting composite sulfur positive electrode sheet according to claim 5, characterized in that, In step (1), the temperature of the hydrothermal reaction is 100-200℃ and the time is 4-24h.

8. The method for preparing the self-supporting composite sulfur positive electrode sheet according to claim 5, characterized in that, In step (1), the second metal compound includes one or more of chloroplatinic acid, chloropalladic acid, silver nitrate, and chloroauric acid; And / or, the molar concentration of the second metal compound in the solution is 0.5-20 mmol / L; And / or, the molar concentration of methanol in the solution is 0.05-1 mol / L; And / or, the wavelength of the ultraviolet irradiation is 200-365nm, and the irradiation time is 10-120min.

9. The method for preparing the self-supporting composite sulfur positive electrode sheet according to claim 5, characterized in that, In step (2), the temperature of the mixed heating is 140-180℃ and the time is 6-24h.

10. A water-based zinc battery, characterized in that, Includes the self-supporting composite sulfur positive electrode sheet according to any one of claims 1-4 or the self-supporting composite sulfur positive electrode sheet obtained by the preparation method according to any one of claims 5-9.

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