A high specific surface area porous carbon / sulfur composite material, a preparation method and application thereof, and a water-based zinc-sulfur battery

Abstract

The application discloses a kind of high specific surface area porous carbon / sulfur composite material and its preparation method and application, water-based zinc-sulfur battery, it is related to carbon material technical field.The method includes: biomass precursor is washed and dried, and pretreated precursor is obtained;Then with sulfate in proportion is mixed, and is uniformly prepared carbon / sulfur composite material precursor after preliminary grinding, subsequent ball milling;Carbon / sulfur composite material precursor is placed in tube furnace, carbonizes under inert atmosphere and is obtained high specific surface area porous carbon / sulfur composite material after acid washing.The three-dimensional porous carbon / sulfur composite material obtained by the application can obtain carbon / sulfur composite material with high sulfur content after hydrochloric acid acid washing, and its electrochemical, kinetic performance is obviously superior to previously reported work.Benefiting from high uniformity composite material, three-dimensional carbon nanostructure crosslinked with each other and developed specific surface area, the obtained porous carbon material shows excellent electrochemical performance as positive electrode material of water-based zinc-sulfur battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon materials, and particularly relates to a high specific surface area porous carbon / sulfur composite material, a preparation method and application thereof, and an aqueous zinc-sulfur battery. BACKGROUND

[0002] With the increasing proportion of renewable energy (such as solar and wind energy) in the global energy structure, there is an increasing demand for large-scale energy storage systems, and effective energy storage technologies are needed to address the challenges of intermittency and unpredictability. Electrochemical energy storage systems play a key role in the conversion and storage of electrical energy, among which rechargeable batteries are one of the most important technologies for grid-scale energy storage, with the advantages of high flexibility and high capacity storage. However, there are many types of rechargeable battery technologies, and currently, traditional lithium-ion batteries (LIB S ) dominate the market, but have limitations in terms of energy density, cost, material scarcity, etc., and the use of organic solutions and overactive lithium metal can cause safety problems, hindering their practical application in GES, forcing the search for new storage solutions.

[0003] Aqueous batteries, especially aqueous zinc-ion batteries (AZMBs), have attracted great interest from researchers because of their low cost (2.9 dollars per kilogram -1 ), high theoretical capacity (819 mA h g -1 ), and compatibility with aqueous electrolytes, and their inherent safety and high capacity make them a promising alternative to lithium-ion batteries, and aqueous rechargeable zinc-ion batteries have become a promising safe and high-energy storage device. Zinc is an extremely attractive material, and early use of manganese-based, vanadium-based and organic-based cathodes and traditional Zn 2+ intercalation / deintercalation mechanism. Recently, multi-electron transfer conversion cathodes have replaced traditional mechanisms as a new research hotspot, thereby improving the capacity of aqueous rechargeable zinc-ion batteries.

[0004] Sulfur (S) is the most representative cathode for aqueous rechargeable zinc-ion batteries because of its high capacity (1675 mA h g -1 ) and low cost of 0.25 dollars per kilogram. Studies have shown that the energy density of aqueous zinc-sulfur primary batteries is 1083.3 Wh kg -1 , however, when used in rechargeable batteries, the primary battery has significant polarization and a low discharge platform of 0.3 V, which is attributed to the slow kinetics of the sulfur electrode. Low discharge platforms have also been reported in nickel-sulfur, copper-sulfur and lead-sulfur batteries, in addition, the formation of passivated ZnS is another reason that hinders practical use.

[0005] Currently, significant progress has been made in improving the anode electrochemical performance and stability. However, the practical application of AZMBs (aqueous zinc-sulfur batteries) still faces many limitations due to the lack of high energy density and reversible cathode materials, which affects its scalability and reliability. In existing research, the positive electrode of the aqueous zinc-sulfur battery is usually composed of porous carbon material and active substance sulfur, and the sulfur positive electrode is prepared by using the traditional molten diffusion method. However, due to the high viscosity of molten sulfur, it is difficult to penetrate into micropores and mesopores, which often leads to the blockage of the pores of the carbon carrier, resulting in the specific surface area of the final positive electrode material being much lower than the high specific surface area of the original carrier material. Lower specific surface area means insufficient electrode-electrolyte interface, which leads to slow electrode kinetics. On the other hand, although the conversion type sulfur cathode has the potential to provide high capacity and maintain structural stability during cycling, the reduction reaction of the sulfur cathode in AZMBs exhibits a low discharge platform of 0.3-0.47V. In addition, the capacity of the sulfur cathode rapidly decays during cycling, which further limits the performance of AZMBs. Compared with other metal-sulfur batteries, the higher binding energy of ZnS exacerbates the irreversible redox reaction in aqueous zinc-ion batteries. Various solutions have been developed to improve the sulfur conversion kinetics in AZMBs, including doping redox catalysts or adding redox mediators to the electrolyte. Although the current solutions have improved the electrochemical performance of aqueous zinc-sulfur batteries to varying degrees, the discharge voltage is still challenged by the low electrochemical potential of sulfur reduction.

[0006] Based on the defects of the current preparation of aqueous zinc-sulfur batteries and the low discharge platform, it is necessary to improve it. SUMMARY

[0007] Based on the above reasons, in view of the problems or defects existing in the prior art, the purpose of the present application is to provide a high specific surface area porous carbon / sulfur composite material and its preparation method and application, and an aqueous zinc-sulfur battery, to solve or at least partially solve the above technical defects existing in the prior art.

[0008] In a first aspect, the present application provides a preparation method of a high specific surface area porous carbon / sulfur composite material, comprising the following steps:

[0009] Preparation of carbon / sulfur composite material precursor;

[0010] The carbon / sulfur composite material precursor is placed in a tube furnace and carbonized and acid washed under an inert atmosphere to obtain a high specific surface area porous carbon / sulfur composite material;

[0011] The preparation method of the carbon / sulfur composite material precursor comprises the following steps:

[0012] The biomass precursor is washed and dried to obtain a pretreated precursor;

[0013] The pretreated precursor is mixed with the sulfate salt in proportion, and is uniformly ground by primary grinding and subsequent ball milling to obtain the carbon / sulfur composite material precursor.

[0014] Further, the specific steps of mixing the pretreated precursor with the sulfate salt in proportion and uniformly grinding by primary grinding and subsequent ball milling are as follows:

[0015] The pretreated precursor is mixed with the sulfate salt in proportion, and is uniformly ground by primary grinding and subsequent ball milling to obtain the carbon / sulfur composite material precursor.

[0016] Specifically, the pretreated precursor is mixed with the sulfate salt in proportion, and is uniformly ground by primary grinding and subsequent ball milling to obtain the carbon / sulfur composite material precursor.

[0017] Preferably, in the above technical solution, the rotation speed of the ball milling is 60-360 r / min.

[0018] Further, in the above technical solution, the biomass precursor includes but is not limited to jujube leaf powder, pine needle powder, turmeric powder, and onion powder.

[0019] Further, in the above technical solution, the sulfate salt includes but is not limited to potassium sulfate, potassium persulfate, and potassium thiosulfate.

[0020] Further, in the above technical solution, the specific steps of carbonizing the carbon / sulfur composite material precursor in a tube furnace in an inert atmosphere are as follows:

[0021] The carbon / sulfur composite material precursor is placed in a tube furnace, and is heated to 700-900℃ at a rate of 3-7℃ / min in an inert atmosphere, and is kept for 1-2 h to obtain the high specific surface area porous carbon / sulfur composite material. It should be noted that when the carbonization temperature is lower than 700℃ or higher than 900℃, the high specific surface area porous carbon / sulfur composite material cannot be prepared.

[0022] Further, in the above technical solution, the inert gas includes but is not limited to argon, helium, and nitrogen.

[0023] Further, in the above technical solution, the specific steps of carbonizing the carbon / sulfur composite material precursor in a tube furnace in an inert atmosphere are as follows:

[0024] In a second aspect, the present application further provides a high specific surface area porous carbon / sulfur composite material, which is prepared by the above-mentioned method.

[0025] In a third aspect, the present application further provides an application of the high specific surface area porous carbon / sulfur composite material prepared by the above-mentioned method as an electrode material of a water-based zinc-sulfur battery.

[0026] In a fourth aspect, the present application further provides a water-based zinc-sulfur battery, which comprises a positive electrode, a negative electrode, an electrolyte and a separator.

[0027] The positive electrode comprises the above-mentioned high specific surface area porous carbon / sulfur composite material.

[0028] The roles of the raw materials used in the present application are as follows:

[0029] In the in-situ loading method, the biomass is mainly responsible for providing the precursor, and the potassium sulfate mainly plays a role in activation and pore formation, so that the product has a high specific surface area and pore volume.

[0030] The high specific surface area porous carbon / sulfur composite material, the preparation method and application thereof, and the water-based zinc-sulfur battery of the present application have the following beneficial effects compared with the prior art:

[0031] (1) The preparation method of the high specific surface area porous carbon / sulfur composite material of the present application does not use a hard template agent, an additional activator and an additional sulfur source for secondary loading, directly uses a sulfate as a sulfur source, uniformly mixes the sulfate with a pretreated biomass precursor at room temperature, activates the sulfate at high temperature, and grows a three-dimensional porous carbon / sulfur composite material through in-situ loading, so that a carbon / sulfur composite material with a high sulfur content can be obtained through hydrochloric acid washing, and the electrochemical and kinetic performance of the carbon / sulfur composite material is obviously superior to that of the previously reported work. Due to the high uniformity of the composite material, the three-dimensional carbon nanostructure and the developed specific surface area, the obtained porous carbon material exhibits excellent electrochemical performance as a positive electrode material of a water-based zinc-sulfur battery.

[0032] (2) The water-based zinc-sulfur battery of the present application uses the high specific surface area porous carbon / sulfur composite material as a positive electrode, and due to the developed pore structure and the three-dimensional carbon nanostructure of the high specific surface area porous carbon / sulfur composite material, the use of the high specific surface area porous carbon / sulfur composite material as a positive electrode material enables the water-based zinc-sulfur battery to have a high specific capacity, excellent rate performance and excellent comprehensive electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0034] Figure 1 XRD pattern of the high specific surface area porous carbon / sulfur composite material prepared in Example 1 of the present application;

[0035] Figure 2 (a)-(b), (c)-(e) are SEM morphology and mapping pattern of the high specific surface area porous carbon / sulfur composite material prepared in Example 1 of the present application, respectively;

[0036] Figure 3 N2 adsorption-desorption thermodynamic curve of the high specific surface area porous carbon / sulfur composite material prepared in Example 1 of the present application;

[0037] Figure 4 Constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in Application Example 1 of the present application at a current density of 0.5 A / g;

[0038] Figure 5 Constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in Application Example 2 of the present application at a current density of 0.5 A / g;

[0039] Figure 6 Constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in Application Example 3 of the present application at a current density of 0.5 A / g;

[0040] Figure 7 Constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in Application Example 4 of the present application at a current density of 0.5 A / g;

[0041] Figure 8 Constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in Application Example 5 of the present application at a current density of 0.5 A / g;

[0042] Figure 9 Constant current charge-discharge curve of the aqueous zinc-sulfur battery obtained in Comparative Application Example 1 at a current density of 0.5 A / g. -1 DETAILED DESCRIPTION

[0043] ​The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0044] The present application provides a preparation method of a high specific surface area porous carbon / sulfur composite material, comprising the following steps:

[0045] S1, preparing a carbon / sulfur composite material precursor;

[0046] S2, placing the carbon / sulfur composite material precursor in a tube furnace, carbonizing under an inert atmosphere, and acid washing to obtain a high specific surface area porous carbon / sulfur composite material;

[0047] The preparation method of the carbon / sulfur composite material precursor comprises the following steps:

[0048] S11, washing and drying a biomass precursor such as jujube tree leaf powder to obtain a pretreated precursor;

[0049] S12, uniformly grinding and ball milling the pretreated precursor and a sulfate salt in a certain proportion to obtain a carbon / sulfur composite material precursor.

[0050] It should be noted that the preparation method of the high specific surface area porous carbon / sulfur composite material provided in the present application does not use a hard template agent, an additional activator, and an additional sulfur source for secondary loading. Instead, a sulfate salt is directly used as a sulfur source, uniformly mixed with a pretreated precursor at room temperature, activated by the sulfate salt at high temperature, and grown through in-situ loading to obtain a three-dimensional porous carbon / sulfur composite material. The carbon / sulfur composite material with high sulfur content can be obtained through acid washing, and its electrochemical and kinetic performance is obviously better than that of previously reported works. Due to the high uniformity of the composite material, the three-dimensional carbon nanostructure crosslinked with each other, and the developed specific surface area, the obtained porous carbon material exhibits excellent electrochemical performance as a positive electrode material of a zinc-sulfur battery.

[0051] In a preferred embodiment of the present application, the carbon / sulfur composite material precursor is placed in a tube furnace, heated to 700-900℃ at a rate of 3-7℃ / min under an inert atmosphere, and kept for 1-2h to obtain a high specific surface area porous carbon / sulfur composite material.

[0052] Specifically, the inert gas includes but is not limited to argon, helium, nitrogen, and the like.

[0053] In some embodiments, the method for preparing the carbon / sulfur composite precursor further comprises the following steps: the pretreated precursor is preliminarily ground with a sulfate in a mortar at a ratio of 1:0.5-1:3, and then the material is placed in a ball mill tank for ball milling at a speed of 60-360 r / min for 0.5-12 h, and after grinding, the material is dried at 65-85 ℃ to obtain a uniformly dispersed material, which is the carbon / sulfur composite precursor.

[0054] In some embodiments, the carbonized product is pickled with a 0.1-3 mol / L dilute hydrochloric acid or dilute sulfuric acid solution for 0.5-5 h, and the product is repeatedly washed with deionized water and anhydrous ethanol for 3-5 times until the pH value of the solution after washing is neutral, and the product is dried at 65-80 ℃ until the water is evaporated.

[0055] In preferred embodiments of the present application, the concentration of the dilute hydrochloric acid or dilute sulfuric acid solution is 0.5-2 mol / L.

[0056] In some embodiments, the method for preparing the high specific surface area porous carbon / sulfur composite material, the biomass precursor includes but is not limited to jujube leaf, pine needle powder, turmeric powder, onion powder, etc.

[0057] The sulfate includes but is not limited to potassium sulfate, potassium persulfate, potassium thiosulfate, etc.

[0058] Based on the same inventive concept, the embodiments of the present application also provide a water-based zinc-sulfur battery, which comprises: a positive electrode, a negative electrode, an electrolyte, and a separator;

[0059] The positive electrode comprises the high specific surface area porous carbon / sulfur composite material prepared above.

[0060] The negative electrode is a zinc sheet.

[0061] The electrolyte is a 1-3 mol / L zinc sulfate aqueous solution + 0.06 mol / L zinc iodide additive.

[0062] The separator is a glass fiber filter paper.

[0063] Specifically, the positive electrode is prepared by mixing the high specific surface area porous carbon / sulfur composite material, conductive carbon black, and an adhesive in alcohol at a mass ratio of 8:1:1 to form a slurry, which is coated on a stainless steel current collector, and then dried at 80 ℃ to obtain the positive electrode; the adhesive is PVDF.

[0064] Specifically, the positive electrode of the water-based zinc-sulfur battery of the present application comprises the high specific surface area porous carbon / sulfur composite material. Due to the high uniformity, the three-dimensional carbon nanometer structure and the developed specific surface area of the high specific surface area porous carbon / sulfur composite material, the obtained porous carbon material exhibits excellent electrochemical performance as the positive electrode material of the water-based zinc-sulfur battery.

[0065] The following further illustrates the preparation method of the porous carbon / sulfur composite material of the present application with specific examples.

[0066] Example 1

[0067] The present application provides a preparation method of a high specific surface area porous carbon / sulfur composite material, comprising the following steps:

[0068] S1, washing and drying jujube leaf powder to obtain pretreated jujube leaf powder; 6g of the pretreated jujube leaf powder and 6g of potassium sulfate salt are preliminarily ground in a mortar at a mass ratio of 1:1, and then the obtained mixture is placed in a ball mill tank for ball milling at 0.5-12h, with a rotation speed of 60-360rpm, and after grinding and drying, a uniformly dispersed material is obtained, which is a carbon / sulfur composite material precursor.

[0069] S2, placing the carbon / sulfur composite material precursor in a tube furnace, heating to 800℃ at 5℃ / min under an argon atmosphere, and keeping for 2h, to obtain a high specific surface area porous carbon / sulfur composite material;

[0070] S3, stirring the carbonized product with 2mol / L dilute hydrochloric acid solution for 2h, and repeatedly filtering and washing the acid-washed product with deionized water and anhydrous ethanol for 3-5 times until the pH value of the washing solution is neutral, and drying the product at 85-95℃ until the water is evaporated.

[0071] Example 2

[0072] The preparation method of a high specific surface area porous carbon / sulfur composite material of the present example is basically the same as that of Example 1, and the only difference is that the carbonization temperature in step S2 of the present example is 700℃, and the other processes are the same.

[0073] Example 3

[0074] The preparation method of a high specific surface area porous carbon / sulfur composite material of the present example is basically the same as that of Example 1, and the only difference is that the carbonization temperature in step S2 of the present example is 900℃, and the other processes are the same.

[0075] Example 4

[0076] The preparation method of a carbon / sulfur composite material of the present example is basically the same as that of Example 1, and the only difference is that the mass ratio of the pretreated jujube leaf powder to potassium sulfate salt in step S1 of the present example is 1:0.5, and the other processes are the same.

[0077] Example 5

[0078] The preparation method of the carbon / sulfur composite material of the embodiment is basically the same as that of embodiment 1, and the only difference is that the mass ratio of the pretreated jujube leaf powder to potassium sulfate salt in step S1 of the embodiment is 1:3, and the other processes are the same.

[0079] Comparative example 1

[0080] The carbon / sulfur composite material of the present comparative example is prepared by a traditional melt diffusion method, and the specific steps are as follows: commercial Ketjenblack carbon and sublimed sulfur are ground in a agate mortar at a mass ratio of 1:1 for 40 minutes to ensure that the sulfur loading of the comparative sample is consistent with that of the experimental group. Then, the mixture is placed in a stainless steel reaction kettle and heated to 160°C at a heating rate of 2°C / min in a muffle furnace, and kept for two hours. After the reaction is completed, it is cooled to room temperature to obtain the carbon / sulfur composite material.

[0081] Application example 1

[0082] The aqueous zinc-sulfur battery provided by the application example comprises a positive electrode, a negative electrode, an electrolyte and a separator.

[0083] The preparation method of the positive electrode is as follows: the high specific surface area porous carbon / sulfur composite material prepared in embodiment 1, conductive carbon black and a binder are mixed in alcohol at a mass ratio of 8:1:1 to form a slurry, which is coated on a stainless steel current collector and dried at 80°C to obtain the positive electrode; the binder is PVDF;

[0084] The negative electrode is a zinc sheet.

[0085] The electrolyte is a 3 mol / L zinc sulfate aqueous solution + 0.06 mol / L zinc iodide additive.

[0086] The separator is a glass fiber filter paper.

[0087] Application example 2

[0088] The aqueous zinc-sulfur battery provided by the application example comprises a positive electrode, a negative electrode, an electrolyte and a separator.

[0089] Application example 3

[0090] The aqueous zinc-sulfur battery provided by the application example comprises a positive electrode, a negative electrode, an electrolyte and a separator.

[0091] Application example 4

[0092] The application example provides a water-based zinc-sulfur battery, which has basically the same structure as the application example 1, and the difference is that in the preparation method of the positive electrode of the application example, the carbon / sulfur composite material prepared in the example 4 is used as the active material, and the amount and other processes are the same.

[0093] Application example 5

[0094] The application example provides a water-based zinc-sulfur battery, which has basically the same structure as the application example 1, and the difference is that in the preparation method of the positive electrode of the application example, the carbon / sulfur composite material prepared in the example 5 is used as the active material, and the amount and other processes are the same.

[0095] Comparative application example 1

[0096] The application example provides a water-based zinc-sulfur battery, which has basically the same structure as the application example 1, and the difference is that in the preparation method of the positive electrode of the application example, the carbon / sulfur composite material prepared in the example 5 is used as the active material, and the amount and other processes are the same.

[0097] Performance test

[0098] The XRD spectrum of the porous carbon / sulfur composite material prepared in the application example 1 is shown in Figure 1 .

[0099] As can be seen from Figure 1 , a gentle wide peak appears at about 23°, which belongs to the (002) crystal plane of amorphous carbon.

[0100] The SEM morphology and mapping spectrum of the carbon / sulfur composite material prepared in the application example 1 are shown in Figure 2 . As can be seen from Figure 2 , a high content of sulfur is successfully introduced into the porous carbon, and the carbon, nitrogen, oxygen and sulfur in the prepared porous carbon / sulfur composite material are uniformly distributed.

[0101] The N2 adsorption-desorption thermodynamic curve of the carbon / sulfur composite material prepared in the application example 1 is tested, and the result is shown in Figure 3 . Specifically, the N2 adsorption-desorption thermodynamic curve is tested by using the American ASAP-2460 type specific surface area and pore size analyzer.

[0102] As can be seen from Figure 3 , the adsorption-desorption curve of the porous carbon / sulfur composite material prepared in the example 1 has obvious hysteresis loop, indicating that there are a large number of mesopores in the porous carbon. The final test result shows that the specific surface area of the obtained carbon nanosheet is 494.3 m 2 g-1 .

[0103] The electrochemical performance of the aqueous zinc-sulfur battery assembled in application example 1 was tested by using CHI-660 electrochemical workstation, and the constant current charge-discharge curve of the aqueous zinc-sulfur battery at a current density of 0.5 Ag -1 was tested, and the results are shown in Figure 4 . As can be seen from Figure 4 , the maximum mass specific capacity of the aqueous zinc-sulfur battery is 1493.4 mAh g -1 , and it shows a high voltage discharge platform of 0.71 V and a polarization voltage of 0.42 V.

[0104] Figure 5 and Figure 6 are the constant current charge-discharge curves of the materials prepared at different carbonization temperatures at a current density of 0.5 Ag -1 .

[0105] Among them: Figure 5 is the constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in application example 2 of the present application at a current density of 0.5 Ag -1 ; as can be seen from the figure, after carbonization at 700℃, the assembled battery shows a specific capacity of 1247 mAh g -1 , a discharge platform of 0.5 V and a polarization voltage of 0.64 V.

[0106] Figure 6 is the constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in application example 3 of the present application at a current density of 0.5 Ag -1 ; as can be seen from the figure, after carbonization at 900℃, the assembled battery shows a specific capacity of 1204 mAh g -1 , a discharge platform of 0.51 V and a polarization voltage of 0.63 V.

[0107] Figure 7 and Figure 8 are the constant current charge-discharge curves of the materials prepared at different proportions at a current density of 0.5 Ag -1 .

[0108] Among them: Figure 7 is the constant current charge-discharge curve of the aqueous zinc-sulfur battery assembled in application example 4 of the present application at a current density of 0.5 Ag -1 ; as can be seen from the figure, when the proportion of biomass carbon precursor to potassium sulfate is 1:0.5, the assembled battery shows a specific capacity of 1101 mAh g -1 , a discharge platform of 0.49 V and a polarization voltage of 0.65 V.

[0109] Figure 8The galvanostatic charge-discharge curves of the water-based zinc-sulfur battery assembled by the application example 5 were obtained at a current density of 0.5 A g -1 From the figure, it can be seen that when the biomass carbon precursor and potassium sulfate batching ratio is 1:3, the assembled battery shows a specific capacity of 1161 mAh g -1 , a discharge platform of 0.5 V and a polarization voltage of 0.64 V.

[0110] Figure 9 The galvanostatic charge-discharge curves of the water-based zinc-sulfur battery obtained by the comparative application example 1 were obtained at a current density of 0.5 A g -1 From the figure, it can be seen that the specific capacity of the battery after the comparative sample is assembled is 1200 mAh g -1 , a discharge platform of 0.4 V and a polarization voltage of 0.8 V.

[0111] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An aqueous zinc-sulfur battery, comprising: A positive electrode, a negative electrode, an electrolyte, and a separator; characterized in that: the positive electrode comprises a high specific surface area porous carbon / sulfur composite material; the high specific surface area porous carbon / sulfur composite material is prepared by the following method, with the following steps: Preparation of carbon / sulfur composite precursors; The carbon / sulfur composite material precursor was placed in a tube furnace and heated to 700-900°C at a rate of 3-7°C / min under an inert atmosphere and held for 1-2 hours. Then, it was acid-washed to obtain a porous carbon / sulfur composite material with a high specific surface area. The preparation method of the carbon / sulfur composite precursor includes the following steps: The biomass precursors are washed and dried to obtain pretreated precursors; the biomass precursors include, but are not limited to, jujube leaf powder, pine needle powder, turmeric powder, and onion powder. The pretreated precursor and sulfate are mixed in a mass ratio of 1:0.5 to 1:3, and then subjected to preliminary grinding and subsequent ball milling to obtain the carbon / sulfur composite material precursor; the sulfate includes, but is not limited to, potassium sulfate, potassium persulfate, and potassium thiosulfate.

2. The aqueous zinc-sulfur battery according to claim 1, characterized in that: The ball milling time is 0.5 to 12 hours.

3. The aqueous zinc-sulfur battery according to claim 1, characterized in that: The carbonized product is acid-washed with 0.1–3 mol / L dilute hydrochloric acid or dilute sulfuric acid solution for 0.5–5 hours, and then repeatedly washed with deionized water and anhydrous ethanol 3–5 times until the pH of the solution is neutral. Finally, the product is dried at 65–80°C.

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