Method for modifying porous carbon material for positive electrode of sodium-sulfur battery based on sulfonated cobalt phthalocyanine
By using waste coffee grounds-derived carbon materials and introducing sulfonated cobalt phthalocyanine to form Co4N nanoparticles in room temperature sodium-sulfur batteries, the problems of low conductivity and large volume change of sulfur species in room temperature sodium-sulfur batteries are solved, improving the performance and stability of the batteries and achieving high specific capacity and environmentally friendly reuse.
Patent Information
- Application Number
- CN202510848751.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-24
- Publication Date
- 2025-11-21
AI Technical Summary
Room temperature sodium-sulfur batteries suffer from problems such as low conductivity of sulfur species, large changes in cathode volume, and loss of active material due to the "shuttle effect," which affect battery performance and stability.
Waste coffee grounds-derived carbon material is used as a sulfur carrier, and Co4N nanoparticles are introduced through sulfonated cobalt phthalocyanine to form a catalyst, which improves the catalytic performance of the cathode material. The sulfonated cobalt phthalocyanine is converted into Co4N nanoparticles after heat treatment, which promotes the conversion of polysulfides and avoids the loss of active materials.
It improves the cycle stability and rate performance of room temperature sodium-sulfur batteries, achieves high specific capacity, has good electrochemical performance and low cost, and meets the environmentally friendly reuse target of "dual carbon".
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of room-temperature sodium-sulfur batteries, in particular to a method for synthesizing waste biomass-derived carbon material as a sulfur carrier. BACKGROUND
[0002] With the progress of science and technology, people's research on lithium ion batteries is more and more in-depth, and the technology of lithium ion batteries is more and more mature. The components of lithium ion batteries mainly include positive electrode, negative electrode, separator, electrolyte and shell, among which the positive electrode material has a profound influence on the performance of the battery. The positive electrode material of lithium ion battery can be divided into layered positive electrode material, lithium cobaltate, ternary material, etc.; spinel type positive electrode material, such as lithium nickel manganese oxide, etc.; olivine type positive electrode material, such as lithium iron phosphate, lithium cobalt phosphate, etc. However, the shortage and high price of lithium resources make lithium ion batteries gradually unsuitable for large-scale industry. Compared with lithium ion batteries, room-temperature sodium-sulfur batteries use sodium metal as the negative electrode and sulfur as the active material, which has the advantages of low economic cost, high specific capacity (1675 mAh g -1 ) and high energy density (1274 Wh kg -1 ).
[0003] Although room-temperature sodium-sulfur batteries can meet the needs of the environment and cost, they still have many problems. First, the low intrinsic conductivity of sulfur species will result in low utilization of sulfur active material; second, the volume change of the positive electrode during charging and discharging is large, which is not conducive to the stable cycle of the battery; and third, the notorious "shuttle effect" will make the soluble polysulfides pass through the separator and deposit on the negative electrode, resulting in the loss of active material. To solve the above problems, researchers mainly adopt the method of modifying the positive electrode. Zhang et al. immersed sulfur into atomically Co-decorated hollow carbon nanospheres (S@Con-HC) for use as a positive electrode material for room-temperature sodium-sulfur batteries. The S@Con-HC positive electrode showed excellent durability and durability (Nature Communications, 2018, 9(1): 4082). Xu et al. reported the electrocatalytic effect of VO2 / rGO catalysts on the rapid conversion of long-chain polysulfides into Na2S2 and / or Na2S, which ultimately improved the durability of Na-S batteries (Chemical Engineering Journal, 2020, 379: 122359).
[0004] Therefore, it is essential to find a modification method for the positive electrode material of room-temperature sodium-sulfur batteries to improve the performance of room-temperature sodium-sulfur batteries. SUMMARY
[0005] The application provides a method for modifying porous carbon material for sodium-sulfur battery positive electrode based on sulfonated phthalocyanine cobalt. In the method, waste coffee grounds derived carbon is used as a carbon carrier of sulfur, and Co4N nanoparticles are introduced by using sulfonated phthalocyanine cobalt to realize catalyst loading. The sulfonated phthalocyanine cobalt modified waste coffee grounds derived carbon material and sulfur are mixed to obtain a room temperature sodium-sulfur battery positive electrode material with high electrochemical performance. The waste coffee grounds material has the advantages of low price and wide source range, and the derived carbon material has a large number of micropores and good physical adsorption performance. The sulfonated phthalocyanine cobalt contains Co and N elements, which will be converted into Co4N nanoparticles with high catalytic activity after heat treatment, accelerating the conversion of polysulfides and avoiding the loss of active substances. The waste coffee grounds derived carbon material combined with the sulfonated phthalocyanine cobalt can significantly improve the performance of the room temperature sodium-sulfur battery positive electrode material. The specific synthesis method mainly includes the following steps: Step S1, waste coffee grounds and KOH are added to a mixed solution of water and ethanol, and the KOH is dissolved by stirring; Step S2, sulfonated phthalocyanine cobalt is added to the mixed solution, and the sulfonated phthalocyanine cobalt and the waste coffee grounds are fully mixed and uniformly distributed by vigorous stirring; Step S3, the mixed solution is placed in a centrifuge to realize solid-liquid separation, and the precipitate is placed in an oven to dry overnight; Step S4, the dried powder is placed in a tube furnace and subjected to carbonization heat treatment in an argon-hydrogen gas (95 / 5 vol%) atmosphere; Step S5, the powder after heat treatment is subjected to acid washing with a hydrochloric acid solution, and the powder is dried after acid washing; Step S6, the dried powder and sulfur are mixed, and a sulfur loading process is carried out at high temperature by using a melt diffusion method, and finally a sulfonated phthalocyanine cobalt modified room temperature sodium-sulfur battery positive electrode material is obtained.
[0006] Further, in step S1, the mass ratio of coffee grounds to KOH is controlled to be 3:2, and the volume ratio of water to ethanol is controlled to be 2:1.
[0007] Further, in step S2, the amount of sulfonated phthalocyanine cobalt added is 0-10% of the mass fraction of coffee grounds, and the stirring time is controlled to be greater than 12 h.
[0008] Further, in step S3, the rotation speed of the centrifuge used is 9000 r min -1 , the centrifugation time is controlled to be 3-5 min, and the drying temperature is 60-80 ℃.
[0009] Further, in step S4, the heat treatment is divided into two stages, the first stage heat treatment temperature is 200 ℃, and the heat treatment time is 90 min; the second stage heat treatment temperature is 800 ℃, and the heat treatment time is 180 min. The heating rate of heat treatment is 3-5 ℃ min-1 .
[0010] Further, in step S5, the concentration of hydrochloric acid used for pickling is 2 mol / L -1 , the pickling time is controlled at 1-1.5 h, and the drying temperature is 60-80 DEG C.
[0011] Further, in step S6, the mass ratio of sulfur and the dried powder is 4:6, the heating temperature and time used in the melting diffusion method are 155 DEG C for 10 h and then 200 DEG C for 2 h.
[0012] The advantages of the present application are embodied in the following aspects: 1. The present application uses simple waste coffee grounds material for carbonization as a sulfur carrier for the positive electrode material of the room temperature sodium-sulfur battery, which has the advantages of simple synthesis method and low cost compared with other materials, and has great advantages in the face of increasingly serious environmental problems today. The recycling of waste coffee grounds is also conducive to the early realization of the "double carbon" goal. At the same time, the carbon material obtained from waste coffee grounds has a large number of micropores and a large surface area, and has a strong physical adsorption effect on polysulfides; 2. The present application introduces a sulfonated cobalt phthalocyanine material by a simple liquid phase method. The cobalt phthalocyanine material will derive Co4N nanoparticles with strong catalytic performance in the subsequent heat treatment process, which can greatly increase the catalytic sites in the positive electrode material of the room temperature sodium-sulfur battery, catalyze the conversion of polysulfides, promote the conversion of soluble polysulfides to insoluble polysulfides, avoid the large amount of dissolution of soluble polysulfides, prevent the loss of active material, and improve the cycle stability and rate performance of the room temperature sodium-sulfur battery; 3. The room temperature sodium-sulfur battery positive electrode material synthesized by the method of the present application can realize a reversible specific capacity of 1020.0 mAh / g -1 at 1 C after being assembled into a battery, and has a high specific capacity of 731.7 mAh / g -1 at a high current density of 5 C. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 is the SEM morphology diagram of the waste coffee grounds derived carbon material prepared in Example 1.
[0014] Figure 2 is the SEM morphology diagram of the sulfonated cobalt phthalocyanine modified waste coffee grounds derived carbon material prepared in Example 3.
[0015] Figure 3 is the XRD spectrum diagram of the sulfonated cobalt phthalocyanine modified waste coffee grounds derived carbon material prepared in Example 3.
[0016] Figure 4is the nitrogen adsorption-desorption curve of the sulfonated cobalt phthalocyanine modified waste coffee grounds derived carbon material prepared.
[0017] Figure 5 is the rate performance graph of the sulfonated cobalt phthalocyanine modified room temperature sodium-sulfur battery positive electrode material button half cell prepared.
[0018] Figure 6 is the cycle graph at 1 C of the sulfonated cobalt phthalocyanine modified room temperature sodium-sulfur battery positive electrode material button half cell prepared.
[0019] Figure 7 is the cycle graph at 0.1 C of the room temperature sodium-sulfur battery positive electrode material button half cell prepared in Comparative Example 1. DETAILED DESCRIPTION Example 1
[0020] 700 mg of KOH was weighed into a mixed solution of 33 mL of water and 17 mL of ethanol, and after the KOH was completely dissolved, 1050 mg of waste coffee grounds was added to the mixed solution, and stirred vigorously for 12 h or more. Then, solid-liquid separation was realized by a centrifuge, the centrifugal speed was 9000 r min -1 , and the time was 3-5 min, and the precipitate obtained by centrifugation was dried at 60-80 ℃. The dried powder was ground and put into a tube furnace for carbonization heat treatment, and during the carbonization process, the first stage sintering temperature was 200 ℃, the sintering time was 90 min; the second stage sintering temperature was 800 ℃, the sintering time was 180 min, the atmosphere was argon-hydrogen gas (95 / 5 vol. ), and the heating rate was 3-5 ℃ min -1 . The powder obtained by sintering was acid washed with 2 mol L -1 HCl for 1-1.5 h, and after acid washing, it was washed with ultrapure water until neutral, and then dried at 60-80 ℃, and mixed with sulfur, and then heat treated at 155 ℃ for 10 h, and at 200 ℃ for 2 h to load sulfur at high temperature, to finally obtain a room temperature sodium-sulfur battery positive electrode material. The morphology of the positive electrode material is shown in Figure 1 , its nitrogen adsorption-desorption curve is shown in Figure 4 , the specific surface area is 1194.095 m 2 g -1 , and it is type I isotherm, indicating the presence of internal micropores. It has a specific capacity of 145.9 mAh g -1 at 5 C ( Figure 5 ), and a specific capacity of 950.0 mAh g -1 after 100 cycles at 1 C ( Figure 6 ). Example 2
[0021] The difference between this example and Example 1 is that 1050 mg of waste coffee grounds and 21 mg of sulfonated phthalocyanine cobalt are added to the mixed solution, and stirred vigorously for more than 12 h, and a sulfonated phthalocyanine cobalt modified room temperature sodium-sulfur battery positive electrode material is prepared according to the above method. The positive electrode material has a specific capacity of 600.6 mAh g -1 Figure 5 at 5 C, which is much higher than the discharge specific capacity (145.9 mAh g -1 ) of Example 1, and has a specific capacity of 969.0 mAh g -1 after 100 cycles at 1 C Figure 6 , which is better than Example 1 (730.8 mAh g -1 ). Example 3
[0022] The difference between this example and Example 1 is that 1050 mg of waste coffee grounds and 52.5 mg of sulfonated phthalocyanine cobalt are added to the mixed solution, and stirred vigorously for more than 12 h, and a sulfonated phthalocyanine cobalt modified room temperature sodium-sulfur battery positive electrode material is prepared according to the above method, and its XRD spectrum is shown in Figure 3 , and the Co4N characteristic peak appears, indicating that the sulfonated phthalocyanine cobalt is converted into Co4N nanoparticles during the heat treatment process. The morphology of the positive electrode material is shown in Figure 2 , and the nitrogen adsorption-desorption curve is shown in Figure 4 , the specific surface area is 1173.402 m 2 g -1 , and it is type I isotherm, indicating the presence of internal micropores, and the positive electrode material has a specific capacity of 721.7 mAh g -1 at 5 C Figure 5 , which has the highest discharge specific capacity compared to other examples, and has a specific capacity of 1020.0 mAh g -1 after 100 cycles at 1 C Figure 6 , which has the best electrochemical cycle stability. Example 4
[0023] The difference between this example and Example 1 is that 1050 mg of waste coffee grounds and 105 mg of sulfonated phthalocyanine cobalt are added to the mixed solution, and stirred vigorously for more than 12 h, and a sulfonated phthalocyanine cobalt modified room temperature sodium-sulfur battery positive electrode material is prepared according to the above method. The positive electrode material has a specific capacity of 696.7 mAh g -1 at 5 C Figure 5 , and has a specific capacity of 971.7 mAh g -1 after 100 cycles at 1 C Figure 6 . Comparative Example 1
[0024] 700 mg of coffee residue was weighed and placed in a mixed solution of 33 mL of water and 17 mL of anhydrous ethanol for washing. After 12 h of washing, solid-liquid separation was performed by centrifugation at a speed of 9000 r min -1 for 3-5 min. After centrifugation, drying was performed at 60-80 ℃, and the dried powder was placed in a tube furnace for carbonization heat treatment. In the carbonization process, the first sintering temperature was 200 ℃, the sintering time was 90 min, the second sintering temperature was 800 ℃, the sintering time was 180 min, the atmosphere was argon-hydrogen gas (95 / 5 vol. ), and the heating rate was 3-5 ℃ min -1 . The sintered powder and sulfur were mixed and heated at 155 ℃ for 10 h and at 200 ℃ for 2 h to load sulfur at high temperature, and finally a room-temperature sodium-sulfur battery positive electrode material was obtained. Its cycle performance is shown in Figure 7 It was found through research that, due to the absence of KOH for pore formation, the coffee residue room-temperature sodium-sulfur battery positive electrode material had no discharge specific capacity at a current density of 1 C and had no electrochemical performance.
Claims
1. A method for using porous carbon materials for sodium-sulfur battery cathodes based on sulfonated cobalt phthalocyanine, characterized in that, The method includes the following steps: Step S1: Add waste biomass materials and KOH to a mixed solution of water and ethanol according to the mass ratio, and stir for a certain period of time to completely dissolve the KOH; Step S2: Add catalyst material to the mixed solution and stir vigorously for a period of time to ensure that the catalyst and waste biomass material are mixed evenly. Step S3: Solid-liquid separation is achieved by centrifugation, and the precipitate obtained by centrifugation is dried in an oven overnight; Step S4: The solid obtained after drying is a waste biomass material loaded with catalyst. After grinding and crushing it, it is put into a tube furnace and subjected to carbonization heat treatment in an inert atmosphere. Step S5: The obtained carbon material is acid-washed with hydrochloric acid solution and dried to obtain the catalyst-supported waste biomass-derived carbon material. Step S6: The biomass-derived carbon material with catalyst is mixed with sulfur, and sulfur is loaded at high temperature using a melt diffusion method to finally obtain a catalyst-modified room temperature sodium-sulfur battery cathode material. Waste biomass material is preferably waste coffee grounds. The carbon material derived from waste coffee grounds after KOH pore-forming has a large number of micropores, which is conducive to the physical adsorption of polysulfides. The catalyst is preferably sulfonated cobalt phthalocyanine, which contains Co and N elements. During the heat treatment process, it is transformed into Co4N material with high catalytic activity, which can accelerate the transformation of polysulfides and reduce the loss of active materials. When the amount of sulfonated cobalt phthalocyanine added is 0~10% (mass ratio), it can effectively improve the electrochemical performance of the cathode material of room temperature sodium-sulfur battery.
2. The synthesis method according to claim 1, characterized in that... In step S1, the mass ratio of waste coffee grounds to KOH is 3:2, and the volume ratio of water to ethanol is 2:
1.
3. The synthesis method according to claim 1, characterized in that... In step S2, the stirring time should be greater than 12 hours to ensure that the sulfonated cobalt phthalocyanine and coffee grounds are mixed evenly.
4. The synthesis method according to claim 1, characterized in that... In step S3, the centrifugation time is 3-5 min, and the centrifugation speed is 9000 r / min. -1 The drying temperature is 60~80℃.
5. The synthesis method according to claim 1, characterized in that... In step S4, the inert gas used for heat treatment can be argon or argon-hydrogen, with argon-hydrogen being the preferred choice, and the ratio of argon to hydrogen being 95:
5. The heat treatment process includes a first stage heat treatment and a second stage heat treatment, wherein the temperature of the first stage heat treatment is 200 °C and the time of the first stage heat treatment is 90 min; the temperature of the second stage heat treatment is 800 °C and the time of the second stage heat treatment is 180 min. The heating rate of the heat treatment process is 3~5 °C / min. -1 .
6. The synthesis method according to claim 1, characterized in that... In step S5, the concentration of hydrochloric acid used is 2 mol / L. -1 The pickling time is 1~1.5 h, and the drying temperature is 60~80 ℃.
7. The synthesis method according to claim 1, characterized in that... In step S6, the mass ratio of sulfur to waste coffee grounds material loaded with sulfonated cobalt phthalocyanine is 4:
6. The heating temperature and time used in the melt diffusion method are 155 °C for 10 h and then 200 °C for 2 h.