A lignin-based zinc sulfide-loaded carbon and a preparation method and application thereof

Abstract

The application discloses lignin-based carbon-supported zinc sulfide and a preparation method and application thereof, and comprises the following steps: (1) dissolving a zinc salt in dimethyl sulfoxide, adding lignin and a nitrogen source, and stirring and heating until completely dissolved to obtain a precursor solution; (2) carbonizing the precursor solution under a protective gas atmosphere, wherein the carbonization temperature is 500-1200 DEG C, and then washing, drying and obtaining lignin-based carbon-supported zinc sulfide. The prepared lignin-based carbon-supported zinc sulfide material has a high specific surface area and a hierarchical porous structure, and has a high specific capacity, good rate performance and cycle stability as a negative electrode of a sodium ion battery. The method has the advantages of simple operation, low cost and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion batteries, and particularly relates to a lignin-based carbon-supported zinc sulfide prepared by a liquid-phase carbonization method and application of the zinc sulfide as a negative electrode material of a sodium ion battery. BACKGROUND

[0002] Sodium-ion batteries (SIBs) are a promising low-cost battery technology for large-scale energy storage applications due to their low raw material cost and high abundance of sodium in the earth's crust (Na: 23,600 ppm vs. Li: 20 ppm). Among the widely studied negative materials, hard carbon can provide a capacity of about 300 mAh·g -1 , which is limited for improving the energy density of SIBs. In comparison to hard carbon negative electrodes, conversion-type compound negative electrodes have higher capacity. Metal sulfides are promising SIB negative electrodes due to the following advantages: (1) higher electronic conductivity compared to oxides; (2) higher redox kinetics due to lower bonding energy compared to oxides; (3) higher rate capability compared to alloy-type negative electrodes due to larger interlayer spacing for sodium-ion diffusion.

[0003] Zinc sulfide (ZnS) is a very promising negative electrode material for sodium-ion batteries due to its high theoretical capacity (about 550 mAh·g -1 ), environmental friendliness, and low resource cost of zinc and sulfur. However, the pulverization of ZnS negative electrodes due to volume change during repeated sodiumization / desodiation processes can lead to irreversible structural damage and loss of electronic pathways. To achieve a ZnS negative electrode with high capacity and high cycle stability, the structure of the ZnS negative electrode needs to be stabilized.

[0004] The intrinsic failure reason of the ZnS negative electrode is the pulverization of ZnS nanoparticles due to the intercalation of sodium ions. Therefore, nano-engineering has been used to minimize the structural changes caused by material pulverization. However, ZnS nanoparticles exhibit limited cycle stability due to the loss of contact of the particulate ZnS active material. Therefore, a 3D carbonaceous framework is designed to provide a conductive and linking framework for ZnS nanoparticles.

[0005] The carbon framework or carbon coating can alleviate the volume change due to steric hindrance effects. At the same time, it can maintain the close connection between the zinc sulfide particles and the carbon framework during repeated (de)sodiation processes. In this way, even if the zinc sulfide is pulverized during sodiumization, the conductive pathways between the particles can still be maintained through the carbon framework. The carbon-coated zinc sulfide composite material exhibits high stability and high rate capability.

[0006] Chinese patent CN 109378458 B discloses a method for preparing a sodium-ion battery negative electrode material ZnS / C-SnO2 using tin sludge. The patent uses zinc salt, sulfur source and organic carbon source as raw materials for hydrothermal reaction. After the reaction, the precursor is obtained by centrifugation-washing-ultrasonic dispersion-drying treatment. The preparation method is complicated, time-consuming and labor-intensive, and the preparation cost is high, which is not conducive to popularization and application.

[0007] Chinese patent CN 114229884 A discloses a metal sulfide sodium-ion battery negative electrode material and a preparation method thereof. The patent uses stannous chloride and zinc salt as a mixed solution, adds polyvinylpyrrolidone, and then introduces a mixture of hydrogen sulfide and nitrogen gas as a reaction gas. The preparation method uses toxic hydrogen sulfide gas, which is not conducive to large-scale industrial production.

[0008] Chinese patent CN 109546139 A discloses a metal sulfide / carbon composite material, a preparation method and its application in battery negative electrode material. The patent uses straw as a precursor to prepare a metal sulfide / carbon composite material. The prepared metal sulfide / carbon composite material has a reversible specific capacity of only about 240mAh·g -1 at a current density of 5A·g -1 .

[0009] The preparation method of the above-mentioned zinc sulfide / carbon composite material has problems such as complex preparation process, high equipment requirement, environmental unfriendliness and high cost; the prepared material has poor electrochemical performance. At the same time, if lignin is used as a carbon source, the aggregation structure of lignin will result in the carbon material obtained having a low specific surface area. The preparation of carbon-supported ZnS composite material is always complicated, and additional sulfurizing agent is needed to vulcanize ZnO or other zinc compounds. SUMMARY

[0010] In view of the problems in the prior art that the zinc sulfide / carbon composite material cannot simultaneously consider low cost, simple preparation route and good electrochemical performance, the present application first provides a method for preparing a lignin-based carbon-supported zinc sulfide composite material by directly carbonizing liquid raw materials in one step. The zinc sulfide composite material prepared by the method has high ionic and electronic conductivity and structural stability. At the same time, the dimethyl sulfoxide solvent used in the present application can achieve the goal of saving raw materials and environmental protection through condensation recovery. The zinc sulfide / carbon composite material is applied to the negative electrode material of a sodium-ion battery. The zinc sulfide particles are broken down during charging and discharging, thereby inducing activation to provide high specific capacity. The separated zinc sulfide particles caused by volume change are firmly connected by the strong carbon skeleton to maintain their activity. Therefore, the zinc sulfide / carbon composite material exhibits excellent large-current fast charging and discharging performance, high charging and discharging capacity, and ultra-long cycle life.

[0011] Another object of the present application is to provide the lignin-based carbon-supported zinc sulfide prepared by the above preparation method.

[0012] Still another object of the present application is to provide the application of the lignin-based carbon-supported zinc sulfide as the negative electrode material of sodium ion battery.

[0013] The object of the present application is achieved by the following technical solutions.

[0014] A preparation method of lignin-based carbon-supported zinc sulfide, comprising the following steps:

[0015] (1) dissolving zinc salt in dimethyl sulfoxide, adding lignin and nitrogen source, heating and stirring until completely dissolved to obtain a precursor solution;

[0016] (2) carbonizing the precursor solution under a protective gas atmosphere, the carbonization temperature is 500-1200℃, washing, drying to obtain lignin-based carbon-supported zinc sulfide.

[0017] Preferably, the zinc salt in step (1) is at least one of zinc chloride, zinc acetate and zinc nitrate.

[0018] The lignin is at least one of alkali lignin, enzymatic hydrolysis lignin and lignin sulfonate. The enzymatic hydrolysis lignin is the enzymatic hydrolysis lignin residue obtained in the biological smelting process; the alkali lignin is the alkali lignin extracted from papermaking black liquor; and the lignin sulfonate is sodium lignin sulfonate extracted from sulfite pulping liquor.

[0019] The nitrogen source is at least one of urea, thiourea and melamine.

[0020] Preferably, the concentration of the zinc salt in dimethyl sulfoxide is 0.02-3 mol / L; the mass ratio of lignin to zinc salt is 1:2-1:20; and the mass ratio of nitrogen source to zinc salt is 1:0.5-1:20.

[0021] Preferably, the heating and stirring temperature in step (1) is 50-150℃, and the time is 1-10h.

[0022] Preferably, the carbonization temperature in step (2) is 600-1000℃, and the time is 1-5h.

[0023] Preferably, the concentration of the zinc salt in dimethyl sulfoxide in step (1) is 0.05-3 mol / L; the mass ratio of lignin to zinc salt is 1:5-1:20; and the carbonization temperature in step (2) is 700-900℃, and the time is 2-4h.

[0024] Preferably, the temperature rising rate of the carbonization in step (2) is 0.5-30℃ / min, and the flow rate of the protective gas is 2-100 mL / min; the temperature of the drying in step (2) is 80-120℃, and the drying time is 2-24h.

[0025] Preferably, the washing in step (2) is water washing followed by acid washing, wherein the water washing refers to immersing the carbonized material in water and stirring for 2-48h; the acid washing refers to immersing the dried carbonized material after water washing in acid and stirring for 0.5-48h; the acid used in the acid washing is at least one of hydrochloric acid, sulfuric acid and nitric acid, and the concentration of the acid is 0.1-2 mol / L; the temperature of the drying is 80-120℃, and the drying time is 8-12h.

[0026] The lignin-based carbon-supported zinc sulfide prepared by the above method is applied as a negative electrode material of a sodium ion battery.

[0027] The material of the application is used to prepare a negative electrode of a sodium ion battery: lignin-based carbon-supported zinc sulfide material, acetylene black conductive agent and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1 are weighed, the PVDF is dissolved in an appropriate amount of 1-methyl-2-pyrrolidone (NMP) and stirred until completely dissolved, the uniformly ground active material and acetylene black are then added to the above solution, and the slurry is continuously stirred to ensure uniform mixing. Then the slurry is uniformly coated on a round copper foil (12mm in diameter), dried in a vacuum oven at 100℃, and finally pressed flat on a tablet press at a pressure of 10MPa to obtain an electrode sheet.

[0028] The prepared electrode sheet, sodium sheet and separator are assembled into a CR2025 button-type sodium ion battery in a glove box filled with high-purity argon. -1 The charge-discharge performance and cycle stability of the sodium ion battery are tested by using a battery test system.

[0029] The lignin-based carbon-supported zinc sulfide has a specific surface area of 600-1000m 2 / g and shows an encapsulation structure of carbon-coated ZnS nanoparticles; a sodium ion half-battery is assembled in a 1mol / L NaPF6 DME electrolyte, and the capacity of the sodium ion battery is 409-584mAh·g -1 , which embodies excellent rate performance. The capacity retention rate is 85.4% and the coulombic efficiency is close to 100% after 4000 cycles at a current density of 10A·g -1 , which shows excellent cycle stability.

[0030] The lignin-based carbon-supported zinc sulfide prepared by the above liquid-phase carbonization method and the application of the same as a negative electrode material of a sodium ion battery.

[0031] The present application utilizes zinc salt as zinc source, lignin as carbon source, dimethyl sulfoxide solvent to provide sulfur source, and urea / thiourea / triamine as nitrogen source. Through simple liquid phase carbonization, pickling, filtration and drying, lignin-based carbon loaded zinc sulfide is prepared. The prepared lignin-based carbon loaded zinc sulfide material has high specific surface area and hierarchical porous structure, and has high specific capacity, good rate performance and cycle stability as a negative electrode of sodium ion battery. The carbon skeleton coating is the key to stabilize the ZnS negative electrode, and the confinement of carbon skeleton to ZnS nanoparticles ensures the continuous conductive path between ZnS nanoparticles and stabilizes the active mass structure in the cycle process. The method has the characteristics of simple operation and low cost. This work provides a practical method for designing high-performance sodium ion battery stable conversion electrode, which is conducive to industrial promotion.

[0032] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0033] (1) The present application utilizes lignin and zinc salt to construct a solution state precursor in dimethyl sulfoxide solution. Lignin has good dispersibility in the solvent and is uniformly mixed with the zinc source. The lignin-based carbon loaded zinc sulfide composite is prepared by one-step carbonization using liquid phase carbonization method. The preparation process is simple, no hydrothermal reaction and additional sulfuration step are needed, and the volatilized dimethyl sulfoxide in the carbonization process can be recycled, solving the environmental pollution problem caused by excess sulfuration agent. Therefore, the present application has the advantages of simple preparation process, low cost and resource-friendly.

[0034] (2) The lignin-based carbon loaded zinc sulfide obtained in the present application has high specific surface area, rich pore structure and stable three-dimensional carbon skeleton. The high specific surface area can provide rich sodium intercalation active sites; the rich pore structure can shorten the mass transfer distance of ions, so that the lignin-based carbon loaded zinc sulfide negative electrode material has high capacity and rate performance. Compared with the reported zinc sulfide / carbon composite negative electrode material, the negative electrode material has excellent cycle stability and excellent high-current fast charge and discharge performance. At a current density of 10 A·g -1 , it can stably cycle for 4000 cycles, and the discharge specific capacity is as high as 350 mAh·g -1 .

[0035] (3) Zinc sulfide particles are easily crushed during charge and discharge. The product obtained by liquid phase carbonization treatment is a composite of ZnS particles and carbon. The presence of carbon skeleton significantly improves the electrical conductivity and structural stability of ZnS nanoparticles. By forming a conductive carbon skeleton, the crushed zinc sulfide particles are connected to maintain their activity, thereby improving the cycle stability of the material. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1is a SEM image of the lignin-based carbon-supported zinc sulfide (ZnS@NC) of Example 1 (magnification of 10,000 times).

[0037] Figure 2 is a nitrogen adsorption-desorption isotherm curve of the lignin-based carbon-supported zinc sulfide (ZnS@NC) of Example 1.

[0038] Figure 3 is a pore size distribution graph of the lignin-based carbon-supported zinc sulfide (ZnS@NC) of Example 1.

[0039] Figure 4 is a graph of the specific capacitance of the lignin-based carbon-supported zinc sulfide (ZnS@NC) of Example 1 as a negative electrode for a sodium ion battery, which varies with current density.

[0040] Figure 5 is the cycle performance of the lignin-based carbon-supported zinc sulfide (ZnS@NC) of Example 1 as a negative electrode for a sodium ion battery at a current density of 10 A·g -1

[0041] Figure 6 is a graph of the specific capacitance of the zinc sulfide (ZnS) of Comparative Example 1 as a negative electrode for a sodium ion battery, which varies with current density. DETAILED DESCRIPTION

[0042] The present application will be described in further detail by the following examples and drawings, but the embodiments of the present application are not limited thereto.

[0043] In the present application, unless otherwise specified, the procedures were carried out under conventional conditions or under the conditions recommended by the manufacturer. The raw materials, reagents, etc. used, unless otherwise specified, were all commercially available conventional products.

[0044] Example 1

[0045] (1) 20 g of zinc chloride was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 90°C until completely dissolved.

[0046] (2) 2 g of alkali lignin was added to the solution of step (1), and stirred at 90°C for 2 h.

[0047] (3) 5 g of urea was added to the solution of step (2), and stirred at 90°C for 5 h.

[0048] ​(4) The liquid obtained in step (3) is pyrolyzed and carbonized at 700°C for 2h under a nitrogen atmosphere at a gas flow rate of 60mL / min, and the temperature is raised at a rate of 5°C / min. After the reaction, the product is washed with deionized water for 12h, dried at 80°C for 8h, soaked in 1mol / L hydrochloric acid for 12h, vacuum filtered, and dried at 90°C for 10h to obtain a lignin-based carbon-supported zinc sulfide material, which is named ZnS@NC.

[0049] (5) The prepared ZnS@NC has a specific surface area of 874m 2 / g.

[0050] ZnS@NC, conductive carbon black, and PVDF (polyvinylidene fluoride) are mixed at a mass ratio of 8:1:1, and ultrapure water is added to prepare a slurry of sodium ion battery electrode material. The slurry is coated on a copper foil at a thickness of 150μm, and then dried and rolled to obtain a circular electrode sheet with a diameter of 14mm.

[0051] The scanning electron microscope (SEM) image of ZnS@NC is shown in Figure 1 The morphology of ZnS@NC is blocky. During carbonization, the solvent dimethyl sulfoxide volatilizes, and lignin generates a carbon conductive framework. ZnS nanoparticles are wrapped by the carbon derived from lignin during carbonization.

[0052] Figure 2 and Figure 3 are the nitrogen adsorption-desorption curve and pore size distribution graph of ZnS@NC. Figure 2 The nitrogen adsorption amount increases in the low adsorption pressure region, indicating the presence of micropores, and the nitrogen adsorption amount increases and the adsorption ring lags significantly in the high adsorption pressure region, indicating the presence of mesopores. Figure 3 The pore size distribution graph also verifies this conclusion.

[0053] The prepared sodium ion battery electrode sheet is used as a working electrode, a sodium metal sheet is used as a counter electrode, and 1mol / L NaPF6 (DME as solvent) is used as an electrolyte to assemble a sodium ion half-cell to test the sodium ion storage performance of ZnS@NC, wherein DME is ethylene glycol dimethyl ether.

[0054] Figure 4 is a curve graph of the specific capacitance of ZnS@NC as a negative electrode of a sodium ion battery as a function of current density. At a current density of 0.05A·g -1 , ZnS@NC has a specific capacity of 584mAh·g -1 , and at 5A·g -1 , it still has a specific capacity of 477mAh·g -1 , indicating that ZnS@NC has excellent capacity and rate performance when applied as a negative electrode of a sodium ion battery.

[0055] Figure 5 The cycle performance of ZnS@NC as a negative electrode for sodium ion batteries at a current density of 10 A·g -1 The specific capacity of ZnS@NC in the first cycle was 139 mAh·g -1 After 4000 cycles, it still had a specific capacity of 323 mAh·g -1 , indicating that ZnS@NC has excellent cycle stability as a negative electrode for sodium ion batteries.

[0056] Example 2

[0057] (1) 36 g of zinc acetate was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 100°C until completely dissolved.

[0058] (2) 6 g of enzymatic lignin was added to the solution of step (1), and stirred at 100°C for 3 h.

[0059] (3) 9 g of thiourea was added to the solution of step (2), and stirred at 100°C for 4 h.

[0060] (4) The liquid obtained in step (3) was pyrolyzed and carbonized at 900°C for 3 h under an argon atmosphere at a gas flow rate of 50 mL / min, with a temperature rise rate of 10°C / min. After the reaction was completed, the material was washed with deionized water for 8 h, dried at 80°C for 8 h, soaked in 1 mol / L hydrochloric acid for 12 h, vacuum filtered, and dried at 90°C for 10 h to obtain an enzymatic lignin-based carbon-supported zinc sulfide material, designated as ZnS@EHLC-900.

[0061] Example 3

[0062] (1) 40 g of zinc nitrate was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 80°C until completely dissolved.

[0063] (2) 4 g of sodium lignosulfonate was added to the solution of step (1), and stirred at 80°C for 1 h.

[0064] (3) 8 g of melamine was added to the solution of step (2), and stirred at 80°C for 3 h.

[0065] (4) The liquid obtained in step (3) was pyrolyzed and carbonized at 800°C for 4 h under a nitrogen atmosphere at a gas flow rate of 40 mL / min, with a temperature rise rate of 2°C / min. After the reaction was completed, the material was washed with deionized water for 6 h, dried at 80°C for 8 h, soaked in 1 mol / L hydrochloric acid for 12 h, vacuum filtered, and dried at 90°C for 10 h to obtain a sodium lignosulfonate-based carbon-supported zinc sulfide material, designated as ZnS@LSC-800.

[0066] Example 4

[0067] (1) 0.68 g of zinc chloride was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 50°C until completely dissolved.

[0068] (2) 0.34 g of enzymatic hydrolysis lignin was added to the solution of step (1), and stirred at 50°C for 0.5 h.

[0069] (3) 1.36 g of thiourea was added to the solution of step (2), and stirred at 50°C for 1 h.

[0070] (4) The liquid obtained in step (3) was pyrolyzed and carbonized at 500°C for 1 h under a nitrogen atmosphere at a gas flow rate of 30 mL / min, and at a temperature increasing rate of 1°C / min. After the reaction, the product was washed with deionized water for 4 h, dried at 80°C for 10 h, soaked in 0.1 mol / L sulfuric acid for 2 h, vacuum filtered, and dried at 90°C for 10 h to obtain an enzymatic hydrolysis lignin-based carbon-supported zinc sulfide material, which was named ZnS@EHLC-500.

[0071] Example 5

[0072] (1) 1.894 g of zinc nitrate was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 60°C until completely dissolved.

[0073] (2) 0.1894 g of sodium lignosulfonate was added to the solution of step (1), and stirred at 60°C for 1 h.

[0074] (3) 0.3788 g of urea was added to the solution of step (2), and stirred at 60°C for 2 h.

[0075] (4) The liquid obtained in step (3) was pyrolyzed and carbonized at 600°C for 2 h under a nitrogen atmosphere at a gas flow rate of 40 mL / min, and at a temperature increasing rate of 5°C / min. After the reaction, the product was washed with deionized water for 6 h, dried at 80°C for 10 h, soaked in 0.1 mol / L nitric acid for 2 h, vacuum filtered, and dried at 90°C for 10 h to obtain a sodium lignosulfonate-based carbon-supported zinc sulfide material, which was named ZnS@LSC-600.

[0076] Example 6

[0077] (1) 55 g of zinc acetate was added to a three-necked flask containing 100 mL of dimethyl sulfoxide, and stirred in an oil bath at 70°C until completely dissolved.

[0078] (2) 2.75 g of alkali lignin was added to the solution of step (1), and stirred at 70°C for 2 h.

[0079] (3) 2.75 g of melamine was added to the solution of step (2) and stirred at 70°C for 3 h.

[0080] (4) The liquid obtained in step (3) was pyrolyzed and carbonized at 900°C for 3 h under a nitrogen atmosphere at a gas flow rate of 50 mL / min and a temperature increase rate of 10°C / min. After the reaction, the sample was washed with deionized water for 8 h, dried at 80°C for 10 h, soaked in 0.5 mol / L hydrochloric acid for 2 h, vacuum filtered, and dried at 90°C for 10 h to obtain a zinc sulfide material supported on alkali lignin-based carbon, designated as ZnS@ALC-900.

[0081] Comparative Example 1

[0082] (1) 20 g of zinc chloride was added to a three-necked flask containing 100 mL of dimethyl sulfoxide and stirred in an oil bath at 90°C until completely dissolved.

[0083] (2) The liquid obtained in step (1) was pyrolyzed and carbonized at 700°C for 2 h under a nitrogen atmosphere at a gas flow rate of 60 mL / min and a temperature increase rate of 5°C / min. After the reaction, the sample was washed with deionized water for 12 h, dried at 80°C for 8 h, soaked in 1 mol / L hydrochloric acid for 12 h, vacuum filtered, and dried at 90°C for 10 h to obtain a zinc sulfide material, designated as ZnS.

[0084] (3) The obtained ZnS had a specific surface area of 45 m 2 / g.

[0085] ZnS, carbon black, and PVDF were mixed in a mass ratio of 8:1:1, and super-pure water was added to prepare a slurry for a sodium ion battery anode. The slurry was coated on a copper foil at a thickness of 150 μm, and the coated copper foil was dried and rolled, and then cut into a circular electrode sheet with a diameter of 14 mm.

[0086] The prepared sodium ion battery electrode sheet was used as a working electrode, a sodium metal sheet was used as a counter electrode, and 1 mol / L NaPF6 (DME as a solvent) was used as an electrolyte to assemble a sodium ion half-cell, and the electrochemical performance of ZnS was tested.

[0087] Figure 6 A graph of the specific capacitance of ZnS as a function of current density as a sodium ion battery anode. At a current density of 0.05 A·g -1 , ZnS had a specific capacity of 292 mAh·g -1 , and at 5 A·g -1 , it had a specific capacity of 122 mAh·g -1 . This indicates that ZnS with a low specific surface area and a lack of pore structure has low capacity and poor rate performance as a sodium ion battery anode. At 10 A·g -1The specific capacity of ZnS in the first circle is 97mAh·g -1 and only 21mAh·g -1 after 4000 cycles. It shows that the lack of carbon conductive framework alleviates the pulverization caused by the volume change of zinc sulfide in the charge and discharge process, and the cycle performance is poor.

[0088] Comparative Example 2

[0089] (1) 20g of zinc chloride, 2g of alkali lignin, and 5g of thiourea were added to a mortar and ground for 1h to obtain a precursor powder.

[0090] (2) The precursor powder of step (1) was evenly distributed in a porcelain boat.

[0091] (3) The porcelain boat containing the precursor powder obtained in step (2) was pyrolyzed and carbonized at 700℃ under a nitrogen atmosphere at a gas flow rate of 60mL / min with a heating rate of 5℃ / min for 2h. After the reaction, the material was washed with deionized water for 12h, dried at 80℃ for 8h, soaked in 1mol / L hydrochloric acid for 12h, vacuum filtered, and dried at 90℃ for 10h to obtain a lignin-based carbon-supported zinc sulfide material in which lignin and sulfur source and zinc source were physically mixed, which was named PB-ZnS.

[0092] Comparative Example 3

[0093] (1) 20g of zinc chloride was added to a three-necked flask containing 100mL of dimethyl sulfoxide and stirred in a 90℃ oil bath until completely dissolved.

[0094] (2) 2g of alkali lignin was added to the solution of step (1) and stirred at 90℃ for 2h.

[0095] (3) The liquid obtained in step (2) was pyrolyzed and carbonized at 700℃ under a nitrogen atmosphere at a gas flow rate of 60mL / min with a heating rate of 5℃ / min for 2h. After the reaction, the material was washed with deionized water for 12h, dried at 80℃ for 8h, soaked in 1mol / L hydrochloric acid for 12h, vacuum filtered, and dried at 90℃ for 10h to obtain a lignin-based carbon-supported zinc sulfide material in which lignin was not completely dissolved in the solution, which was named ZnS@IC-700.

[0096] Comparative Example 4

[0097] (1) 1.894g of zinc nitrate was added to a three-necked flask containing 100mL of dimethyl sulfoxide and stirred in a 60℃ oil bath until completely dissolved.

[0098] (2) The liquid obtained in step (1) was pyrolyzed and carbonized at 600°C for 2h under a nitrogen atmosphere at a gas flow rate of 40 mL / min with a temperature increase rate of 5°C / min. After the reaction, the sample was washed with deionized water for 6h, dried at 80°C for 10h, soaked in 1 mol / L nitric acid for 2h, vacuum filtered, and dried at 90°C for 10h to obtain a zinc sulfide material, which was named ZnS-600.

[0099] Comparative Example 5

[0100] (1) 55 g of zinc acetate was added to a three-necked flask containing 100 mL of dimethyl sulfoxide and stirred in an oil bath at 70°C until completely dissolved.

[0101] (2) 2.75 g of alkali lignin was added to the solution obtained in step (1) and stirred at 70°C for 2h.

[0102] (3) The liquid obtained in step (2) was pyrolyzed and carbonized at 900°C for 3h under a nitrogen atmosphere at a gas flow rate of 50 mL / min with a temperature increase rate of 10°C / min. After the reaction, the sample was washed with deionized water for 8h, dried at 80°C for 10h, soaked in 0.5 mol / L hydrochloric acid for 12h, vacuum filtered, and dried at 90°C for 10h to obtain a lignin-based carbon-supported zinc sulfide material in which lignin was not completely dissolved in solution, which was named ZnS@IC-900.

[0103] Comparative Example 6

[0104] (1) 0.68 g of zinc nitrate and 0.34 g of enzymatic lignin were added to a mortar and ground for 0.5h to obtain a precursor powder.

[0105] (2) The precursor powder obtained in step (1) was uniformly distributed in a porcelain boat.

[0106] (3) The porcelain boat containing the precursor powder obtained in step (2) was pyrolyzed and carbonized at 700°C for 2h under a nitrogen atmosphere at a gas flow rate of 40 mL / min with a temperature increase rate of 5°C / min. After the reaction, the sample was washed with deionized water for 6h, dried at 80°C for 10h, soaked in 1 mol / L nitric acid for 2h, vacuum filtered, and dried at 90°C for 10h to obtain a lignin and zinc oxide composite material, which was named LC / ZnO.

[0107] Table 1 is a comparison of the specific surface area, pore volume, and reversible specific capacity of the lignin-based carbon-supported zinc sulfide prepared in the above examples and the samples prepared in the above comparative examples.

[0108] Table 1

[0109]

[0110] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method for preparing lignin-based carbon-supported zinc sulfide, characterized in that, Includes the following steps: (1) Dissolve zinc salt in dimethyl sulfoxide, add lignin and nitrogen source, heat and stir until completely dissolved to obtain precursor solution; (2) The precursor solution was carbonized under a protective gas atmosphere at a carbonization temperature of 500-1200 °C, washed and dried to obtain lignin-based carbon-supported zinc sulfide. The zinc salt in step (1) is at least one of zinc chloride, zinc acetate, and zinc nitrate; the lignin is at least one of alkali lignin, enzymatic lignin, and lignin sulfonate; and the nitrogen source is at least one of urea, thiourea, and melamine.

2. The method according to claim 1, characterized in that, The concentration of the zinc salt in dimethyl sulfoxide is 0.02–3 mol / L; the mass ratio of lignin to zinc salt is 1:2–1:20; and the mass ratio of nitrogen source to zinc salt is 1:0.5–1:

20.

3. The method according to claim 1, characterized in that, The heating and stirring in step (1) is carried out at a temperature of 50 to 150°C for 1 to 10 hours.

4. The method according to claim 1, 2, or 3, characterized in that, The carbonization temperature in step (2) is 600-1000 ℃ and the time is 1-5 h.

5. The method according to claim 4, characterized in that, The concentration of zinc salt in dimethyl sulfoxide in step (1) is 0.05–3 mol / L; the mass ratio of lignin to zinc salt is 1:5–1:20; the carbonization temperature in step (2) is 700–900 °C and the time is 2–4 h.

6. The method according to claim 4, characterized in that, The heating rate of carbonization in step (2) is 0.5 to 30 °C / min, and the flow rate of the protective gas is 2 to 100 mL / min; the drying temperature in step (2) is 80 to 120 °C, and the drying time is 2 to 24 h.

7. The method according to claim 1, 2, or 3, characterized in that, The washing process in step (2) involves first washing with water and then washing with acid. The water washing refers to immersing the carbonized material in water and stirring for 2 to 48 hours. The acid washing refers to immersing the carbonized material after water washing in acid and stirring for 0.5 to 48 hours. The acid used for acid washing is at least one of hydrochloric acid, sulfuric acid, and nitric acid, and the concentration of the acid is 0.1 to 2 mol / L.

8. The lignin-based carbon-supported zinc sulfide prepared by the method according to any one of claims 1 to 7.

9. The application of the lignin-based carbon-supported zinc sulfide as described in claim 8 as a negative electrode material for sodium-ion batteries.

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