Preparation method for and use of sodium-ion battery negative electrode material

Abstract

The present disclosure relates to the technical field of sodium-ion batteries. Disclosed are a preparation method for and use of a sodium-ion battery negative electrode material. The method comprises: dropwise adding ammonia liquid into a mixed solution containing a tin salt and a nickel salt, and heating for reaction to obtain NiSn(OH)6 nanospheres; dispersing the NiSn(OH)6 nanospheres in a solvent, adding thioacetamide, and heating for reaction to obtain flower-shaped nanospheres SnS2-NiS; and mixing the flower-shaped nanospheres SnS2-NiS, biochar, and a binder in water, heating for reaction, carrying out solid-liquid separation, drying an obtained solid, and sintering in an inert atmosphere to obtain the sodium-ion battery negative electrode material.

Description

Preparation method and application of sodium ion battery negative electrode material Technical Field

[0001] The present disclosure belongs to the technical field of sodium ion batteries, and particularly relates to a preparation method of a negative electrode material for a sodium ion battery and applications thereof. Background Art

[0002] Lithium-ion batteries have achieved tremendous success over the past two decades. They have been widely used in electronic devices, electric vehicles, and other facilities, and have penetrated into every aspect of life. However, the limited availability of lithium resources has restricted the large-scale application and sustainable development of lithium-ion batteries. Therefore, there is an urgent need to develop alternative energy storage systems. Considering that sodium-ion batteries have lower energy density and voltage than lithium-ion batteries, sodium-ion batteries can be used in situations where volume and portability are not very demanding. Sodium-ion batteries have the advantages of low cost, good interfacial ion diffusion capacity, high ionic conductivity, excellent high and low temperature performance, and good safety performance.

[0003] Although sodium-ion batteries have the above advantages, there are still some problems that need to be solved. Among them, the negative electrode material has very serious volume expansion during the charge and discharge process, which may even lead to electrode breakage, pulverization and poor cycle performance. At present, the main method to solve these problems is to use sodium alloys that can form alloys with sodium as negative electrode materials. Although the initial capacity of the alloy material is high, as the cycle progresses, the alloy volume expands, resulting in a sharp decrease in cycle stability. Therefore, it is necessary to solve these problems of negative electrode material volume expansion and poor conductivity.

[0004] Therefore, there is an urgent need to find anode materials with excellent cycle stability, long life and high rate performance, and to solve the problems of volume expansion and poor conductivity of anode materials.

[0005] Summary of the Invention

[0006] The present disclosure aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present disclosure provides a method for preparing a negative electrode material for a sodium ion battery and its application.

[0007] According to one aspect of the present disclosure, a method for preparing a negative electrode material is provided, comprising the following steps:

[0008] S1: Add ammonia solution to the mixed solution containing tin salt and nickel salt, and then heat to react to obtain NiSn(OH)6 nanospheres; the reaction equation is Sn 4+ +Ni 2+ +6OH - →NiSn(OH)6;

[0009] S2: Dispersing the NiSn(OH)6 nanospheres in a solvent, adding thioacetamide, and then heating for reaction to obtain flower-shaped nanospheres SnS2-NiS, wherein the molar ratio of the NiSn(OH)6 nanospheres to the thioacetamide is 1:(3-5); to synthesize the flower-shaped nanospheres, only an excess of thioacetamide needs to be added. When the molar ratio of thioacetamide to NiSn(OH)6 is greater than 3, a flower-shaped structure can be synthesized, and the reaction equation is: 3CH3CSNH2+NiSn(OH)6→SnS2-NiS+3CH3CONH2+3H2O;

[0010] S3: The flower-shaped nanospheres SnS2-NiS, biochar, and binder are mixed in water, heated for reaction, and then solid-liquid separation is performed. The obtained solid is dried and then sintered under an inert atmosphere to obtain the negative electrode material.

[0011] In some embodiments of the present disclosure, in step S1, the molar ratio of the tin salt to the nickel salt is 1:(1-1.5).

[0012] In some embodiments of the present disclosure, in step S1, after the ammonia solution is added dropwise, stirring is carried out for 1-4 hours, and then heating is carried out for reaction.

[0013] In some embodiments of the present disclosure, in step S1, the temperature of the heating reaction is 100-200° C.; and the time of the heating reaction is 6-12 h.

[0014] In some embodiments of the present disclosure, in step S1, after the heating reaction, the NiSn(OH)6 nanospheres are further washed with water and ethanol, and then dried at 60-70°C for 6-12 hours.

[0015] In some embodiments of the present disclosure, in step S1, the tin salt is at least one of SnCl4, Na2SnO3 or Sn(NO3)4.

[0016] In some embodiments of the present disclosure, in step S1, the nickel salt is at least one of Ni(CH3COO)2, nickel sulfate or nickel chloride.

[0017] In some embodiments of the present disclosure, in step S2, the temperature of the heating reaction is 150-200° C.; and the time of the heating reaction is 18-24 hours.

[0018] In some embodiments of the present disclosure, in step S2, the solvent is at least one of anhydrous ethanol, propanol, or pentanol.

[0019] In some embodiments of the present disclosure, in step S2, after the thioacetamide is added, ultrasonication is performed for 2-6 hours, and then heating reaction is performed.

[0020] In some embodiments of the present disclosure, in step S2, after the heating reaction, the flower-shaped nanospheres are further washed with water and ethanol and freeze-dried for 22-24 hours.

[0021] In some embodiments of the present disclosure, in step S2, the particle size D50 of the flower-shaped nanospheres SnS2-NiS is 80-120 nm.

[0022] In some embodiments of the present disclosure, in step S3, the particle size D50 of the biochar is 6-15 μm.

[0023] In some embodiments of the present disclosure, in step S3, the mass ratio of the flower-shaped nanospheres SnS2-NiS, biochar, and binder is (1-2): (10-20): (0.5-1).

[0024] In some embodiments of the present disclosure, in step S3, the sintering temperature is 700-900° C. and the sintering time is 4-12 hours.

[0025] In some embodiments of the present disclosure, in step S3, the binder is at least one of glucose or sucrose.

[0026] In some embodiments of the present disclosure, in step S3, the heating reaction temperature is 55-85° C. and the time is 2-6 hours.

[0027] In some embodiments of the present disclosure, in step S3, the biochar preparation method is as follows: (1) soaking the biomass raw material in a KOH solution, followed by washing, drying, and grinding to obtain a ground material; (2) pyrolyzing the ground material under anaerobic conditions, followed by washing and drying to obtain the biochar. Further preferably, the KOH solution has a mass fraction of 10-20%; the soaking time is 24-48 hours; the ground material has a particle size of 100-200 mesh; the pyrolysis temperature is 550-750°C, and the pyrolysis time is 2-4 hours.

[0028] In some preferred embodiments of the present disclosure, when preparing the biochar, in step (1), the biomass raw material is at least one of rice husks, wheat straw or sawdust.

[0029] The present disclosure also provides application of the negative electrode material prepared by the preparation method in sodium ion batteries.

[0030] According to a preferred embodiment of the present disclosure, at least the following beneficial effects are achieved:

[0031] 1. During the charge and discharge process of sodium-ion batteries, the insertion / extraction of sodium ions easily causes the volume expansion of the negative electrode material. The biochar disclosed in the present invention provides a self-buffering space for the expansion.

[0032] 2. The SnS2-NiS flower-like structure makes the entire electrode have sufficient Na + Active sites and contact area with electrolyte can buffer volume expansion and shorten the Na + diffusion length.

[0033] 3. The rich internal pores of biochar make the SnS2-NiS particles evenly distributed on the internal pores, effectively preventing the aggregation of SnS2-NiS particles and increasing the capacity of the sodium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present disclosure is further described below with reference to the accompanying drawings and embodiments, wherein:

[0035] FIG1 is a SEM image of flower-shaped nanospheres SnS2-NiS prepared in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the concepts and technical effects of the present disclosure in conjunction with the embodiments to fully understand the purpose, features, and effects of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the present disclosure, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present disclosure.

[0037] Example 1

[0038] This embodiment prepares a sodium ion battery negative electrode material, and the specific process is as follows:

[0039] (1) 10 g of rice husk was added to 100 mL of 10% KOH solution and immersed for 24 h, washed with water until neutral, dried and ground to obtain a ground material;

[0040] (2) The ground material of step (1) was added to a muffle furnace, pyrolyzed at 550°C under a nitrogen atmosphere for 2 h, then washed with deionized water until neutral, and dried to obtain biochar with a particle size D50 of 8.5 μm;

[0041] (3) 1 mol Na2SnO3 and 1 mol Ni(CH3COO)2 were added to a deionized water solution, and then ammonia solution was added dropwise and slowly stirred for 1 h. Finally, the mixture was transferred to a 100 mL autoclave and heated at 100 °C for 6 h. The mixture was washed with deionized water and ethanol, and then dried at 60 °C for 6 h to obtain NiSn(OH)6 nanospheres for collection.

[0042] (4) 1 mol of NiSn(OH)6 nanospheres prepared in step (3) were dissolved in anhydrous ethanol by ultrasonication, 3 mol of thioacetamide was added under stirring, the mixture was ultrasonicated for 2 h, and then transferred to an autoclave and heated at 150°C for 18 h, washed with deionized water and ethanol, and freeze-dried for 24 h to obtain flower-shaped nanospheres SnS2-NiS with a particle size D50 of 92 nm;

[0043] (5) 10 g of biochar and 1 g of flower-like nanospheres SnS2-NiS were added to deionized water, and then 0.5 g of glucose was added. The mixture was reacted at 55 °C for 2 h. After centrifugal drying, the mixture was sintered at 700 °C for 4 h in an Ar atmosphere to obtain the sodium ion battery negative electrode material SnS2-NiS@C.

[0044] Example 2

[0045] This embodiment prepares a sodium ion battery negative electrode material, and the specific process is as follows:

[0046] (1) 12 g of rice husk was added to 100 mL of 10% KOH solution and immersed for 24 h, washed with water until neutral, dried and ground to obtain a ground material;

[0047] (2) adding the ground material of step (1) into a muffle furnace, pyrolyzing it at 600°C under a nitrogen atmosphere for 2.5 hours, then washing it with deionized water until it is neutral, and drying it to obtain biochar with a particle size D50 of 9 μm;

[0048] (3) 1 mol Na2SnO3 and 1.2 mol Ni(CH3COO)2 were added to a deionized water solution, and then ammonia solution was added dropwise and slowly stirred for 2 h. Finally, the mixture was transferred to a 100 mL autoclave and heated at 120 °C for 8 h, washed with deionized water and ethanol, and then dried at 60 °C for 8 h to obtain NiSn(OH)6 nanospheres for collection;

[0049] (4) 1 mol of NiSn(OH)6 nanospheres prepared in step (3) were dissolved in anhydrous ethanol by ultrasonication, 3.5 mol of thioacetamide was added under stirring, the mixture was ultrasonicated for 3 h, and then transferred to an autoclave and heated at 160°C for 20 h, washed with deionized water and ethanol, and freeze-dried for 24 h to obtain flower-shaped nanospheres SnS2-NiS with a particle size D50 of 110 nm;

[0050] (5) 12 g of biochar and 1.2 g of SnS2-NiS flower-shaped nanospheres were added to deionized water, and then 0.6 g of glucose was added. The mixture was reacted at 60 °C for 3 h. After centrifugal drying, the mixture was sintered at 750 °C for 6 h in an Ar atmosphere to obtain SnS2-NiS@C, a negative electrode material for sodium ion batteries.

[0051] Example 3

[0052] This embodiment prepares a sodium ion battery negative electrode material, and the specific process is as follows:

[0053] (1) 13 g of wheat straw was added to 100 mL of 10% KOH solution and immersed for 30 h, washed with water until neutral, dried and ground to obtain a ground material;

[0054] (2) adding the ground material of step (1) into a muffle furnace, pyrolyzing it at 620°C under a nitrogen atmosphere for 3 h, then washing it with deionized water until it is neutral, and drying it to obtain biochar with a particle size D50 of 7 μm;

[0055] (3) 1 mol Na2SnO3 and 1.4 mol Ni(CH3COO)2 were added to a deionized water solution, and then ammonia solution was added dropwise and slowly stirred for 3 h. Finally, the mixture was transferred to a 100 mL autoclave and heated at 150 °C for 10 h. The mixture was washed with deionized water and ethanol, and then dried at 60 °C for 10 h to obtain NiSn(OH)6 nanospheres, which were collected for later use.

[0056] (4) 1 mol of NiSn(OH)6 nanospheres prepared in step (3) were dissolved in anhydrous ethanol by ultrasonication, 4 mol of thioacetamide was added under stirring, the mixture was ultrasonicated for 3 h, and then transferred to an autoclave and heated at 160°C for 22 h, washed with deionized water and ethanol, and freeze-dried for 24 h to obtain flower-shaped nanospheres SnS2-NiS with a particle size D50 of 116 nm;

[0057] (5) 13 g of biochar and 1.4 g of SnS2-NiS flower-like nanospheres were added to deionized water, and then 0.7 g of sucrose was added. The mixture was reacted at 75 °C for 4 h. After centrifugal drying, the mixture was sintered at 800 °C for 9 h in an Ar atmosphere to obtain SnS2-NiS@C, a negative electrode material for sodium ion batteries.

[0058] Example 4

[0059] This embodiment prepares a sodium ion battery negative electrode material, and the specific process is as follows:

[0060] (1) 20 g of sawdust was added to 100 mL of 10% KOH solution and immersed for 48 h, washed with water until neutral, dried and ground to obtain a mill base;

[0061] (2) adding the ground material of step (1) into a muffle furnace, pyrolyzing it at 750°C under a nitrogen atmosphere for 4 hours, then washing it with deionized water until it is neutral, and drying it to obtain biochar with a particle size D50 of 10 μm;

[0062] (3) 1 mol Na2SnO3 and 1.5 mol Ni(CH3COO)2 were added to a deionized water solution, and then ammonia solution was added dropwise and slowly stirred for 4 h. Finally, the mixture was transferred to a 100 mL autoclave and heated at 200 °C for 12 h, washed with deionized water and ethanol, and then dried at 60 °C for 12 h to obtain NiSn(OH)6 nanospheres for collection;

[0063] (4) 1 mol of NiSn(OH)6 nanospheres prepared in step (3) were dissolved in anhydrous ethanol by ultrasound, 5 mol of thioacetamide was added under stirring, the mixture was ultrasound-treated for 6 h, and then transferred to an autoclave and heated at 200°C for 24 h, washed with deionized water and ethanol, and freeze-dried for 24 h to obtain flower-shaped nanospheres SnS2-NiS with a particle size D50 of 108 nm;

[0064] (5) 20 g of biochar and 2 g of flower-like nanospheres SnS2-NiS were added to deionized water, and then 1 g of glucose was added. The mixture was reacted at 85 °C for 6 h. After centrifugal drying, the mixture was sintered at 900 °C for 12 h under Ar atmosphere to obtain the sodium ion battery negative electrode material SnS2-NiS@C.

[0065] Comparative Example 1

[0066] This comparative example prepared a conventional biochar. The difference from Example 4 is that flower-shaped nanospheres SnS2-NiS were not prepared. The specific process is as follows:

[0067] (1) 20 g of sawdust was added to 100 mL of 10% KOH solution and immersed for 48 h, washed with water until neutral, dried and ground to obtain a mill base;

[0068] (2) The ground material of step (1) was added to a muffle furnace, pyrolyzed at 750°C under a nitrogen atmosphere for 4 h, then washed with deionized water until neutral, and dried to obtain biochar with a particle size D50 of 10 μm.

[0069] Comparative Example 2

[0070] This comparative example prepares a sodium ion battery negative electrode material. The difference from Example 4 is that thioacetamide is directly reacted with a tin source and a nickel source. The specific process is as follows:

[0071] (1) 1 mol Na2SnO3 and 1.5 mol Ni(CH3COO)2 were added to a deionized water solution, and then 5 mol thioacetamide was added under stirring. The resulting mixture was ultrasonicated for 6 h, then transferred to an autoclave and heated at 200°C for 24 h, washed with deionized water and ethanol, and freeze-dried for 24 h to obtain sulfide SnS2-NiS;

[0072] (2) 20 g of biochar and 2 g of sulfide SnS2-NiS were added to deionized water, and then 1 g of glucose was added. The mixture was reacted at 85 °C for 6 h. After centrifugal drying, the mixture was sintered at 900 °C for 12 h under Ar atmosphere to obtain the sodium ion battery negative electrode material SnS2-NiS@C.

[0073] Test example

[0074] The negative electrode materials of Examples 1-4 and the comparative example were prepared into negative electrode sheets for sodium ion batteries and assembled into button batteries. -1 The test was carried out in the voltage range of 0.4-2.6V, and the results are shown in Table 1.

[0075] Table 1

[0076] As can be seen from Table 1, Comparative Example 1 uses conventional biochar as the negative electrode material, and its performance is much lower than that of the material containing nickel tin sulfide; Comparative Example 2 directly uses thioacetamide to react with tin source and nickel source, and the synthesized sulfide particles are larger, with a small specific surface area and poor cycle performance.

[0077] While the embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person of ordinary skill in the art without departing from the spirit of the present disclosure. Furthermore, the embodiments of the present disclosure and the features within the embodiments may be combined with one another unless there is a conflict.

Claims

1. A method for preparing a negative electrode material, characterized in that: The following steps are involved: S1: adding ammonia solution to a mixed solution containing tin salt and nickel salt, and then heating the solution to react, thereby obtaining NiSn(OH)6 nanospheres; S2: Dispersing the NiSn(OH)6 nanospheres in a solvent, adding thioacetamide, and then heating to react to obtain flower-shaped nanospheres SnS2-NiS, wherein the molar ratio of the NiSn(OH)6 nanospheres to the thioacetamide is 1:(3-5); S3: The flower-shaped nanospheres SnS2-NiS, biochar and a binder are mixed in water, heated for reaction, and then solid-liquid separation is performed. The obtained solid is dried and then sintered in an inert atmosphere to obtain the negative electrode material.

2. The preparation method according to claim 1, characterized in that: In step S1, the molar ratio of the tin salt to the nickel salt is 1:(1-1.5).

3. The preparation method according to claim 1, characterized in that: In step S1, after the ammonia solution is added dropwise, the mixture is stirred for 1-4 hours and then heated for reaction.

4. The preparation method according to claim 1, characterized in that: In step S1, the temperature of the heating reaction is 100-200°C; the time of the heating reaction is 6-12h.

5. The preparation method according to claim 1, characterized in that: In step S1, after the heating reaction, the NiSn(OH)6 nanospheres are washed with water and ethanol, and then dried at 60-70°C for 6-12 hours.

6. The preparation method according to claim 1, characterized in that: In step S1, the tin salt is at least one of SnCl4, Na2SnO3 or Sn(NO3)4.

7. The preparation method according to claim 1, characterized in that: In step S1, the nickel salt is at least one of Ni(CH3COO)2, nickel sulfate or nickel chloride.

8. The preparation method according to claim 1, characterized in that: In step S2, the temperature of the heating reaction is 150-200°C; the time of the heating reaction is 18-24h.

9. The preparation method according to claim 1, characterized in that: In step S2, the particle size D50 of the flower-shaped nanospheres SnS2-NiS is 80-120 nm.

10. The preparation method according to claim 1, characterized in that: In step S2, the solvent is at least one of anhydrous ethanol, propanol or pentanol.

11. The preparation method according to claim 1, characterized in that: In step S2, after adding the thioacetamide, ultrasonication is performed for 2-6 hours, and then heating reaction is performed.

12. The preparation method according to claim 1, characterized in that: In step S2, after the heating reaction, the flower-shaped nanospheres are washed with water and ethanol and freeze-dried for 22-24 hours.

13. The preparation method according to claim 1, characterized in that: In step S3, the particle size D50 of the biochar is 6-15 μm.

14. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of the flower-shaped nanospheres SnS2-NiS, biochar, and binder is (1-2): (10-20): (0.5-1).

15. The preparation method according to claim 1, characterized in that: In step S3, the sintering temperature is 700-900°C.

16. The preparation method according to claim 1, characterized in that: In step S3, the binder is at least one of glucose or sucrose.

17. The preparation method according to claim 1, characterized in that: In step S3, the heating reaction temperature is 55-85°C and the time is 2-6h.

18. The preparation method according to claim 1, characterized in that: In step S3, the preparation method of the biochar is as follows: (1) soaking the biomass raw material in a KOH solution, and then washing, drying and grinding to obtain a grind; (2) pyrolyzing the grind under anaerobic conditions, and washing and drying to obtain the biochar.

19. The preparation method according to claim 18, characterized in that: When preparing the biochar, in step (1), the biomass raw material is at least one of rice husks, wheat straws or sawdust.

20. Use of the negative electrode material obtained by the preparation method according to any one of claims 1 to 19 in sodium ion batteries.

Images