Phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material and preparation method thereof

Abstract

The invention discloses a phycocyanin-based pea-shaped sodium-ion battery hard carbon negative electrode material and a preparation method thereof, and belongs to the technical field of sodium-ion batteries, and the negative electrode material is prepared by calcining phycocyanin in an air atmosphere, carrying out ball milling, and then carrying out secondary calcination in an inert gas atmosphere. The preparation method is simple in process, no acid or alkali is used in the whole preparation process, the preparation method is suitable for large-scale production, meanwhile, the used phycocyanin precursor can enable the prepared hard carbon negative electrode material to be self-doped with an N element, and the hard carbon negative electrode material with excellent performance can be obtained without an additional N doping step.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material and a preparation method thereof. Background Art

[0002] Sodium ranks seventh in abundance in the earth's crust, accounting for about 2.5% of the total mass of the earth's crust. Compared with lithium, sodium resources are more abundant and widely distributed. Therefore, the development of sodium-ion batteries is an important means to reduce dependence on lithium resources, ensure the security of resource supply, and reduce costs and increase efficiency. When sodium-ion batteries form an industrial chain with scale effects, they can complement the advantages of lithium-ion batteries and have a good application market in low-speed vehicles and large-scale energy storage.

[0003] The negative electrode materials of sodium ion batteries mainly include: hard carbon, soft carbon, transition metal oxides and alloy materials. Among the existing methods, hard carbon negative electrodes have been widely studied due to their advantages such as wide sources of biomass precursors and rich sodium storage sites. They are currently the negative electrode materials with the greatest potential for large-scale production. However, the preparation process of many biomass precursor-based hard carbon negative electrode materials is relatively complicated, and most of them contain acid washing and alkali activation steps, which cause environmental pollution. In addition, the electrochemical properties of the obtained hard carbon materials are poor, making it difficult to be widely used in sodium ion batteries. Patent CN 106744934 A discloses a method for preparing sodium ion battery electrode carbon materials using bamboo. The preparation process is relatively complicated, and the use of acid and alkali will lead to the generation of wastewater and waste gas, so it is not an ideal large-scale application method. CN 113292064A discloses a method for preparing a negative electrode material for sodium ion batteries, but the fermentation cycle is too long and the first coulomb efficiency of the obtained hard carbon negative electrode material is low, which is not suitable for large-scale preparation scenarios. Therefore, it is of great practical significance to develop new biomass precursors and optimize the preparation process of hard carbon negative electrodes. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention proposes a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material and a preparation method thereof, aiming to use phycocyanin extracted from Spirulina platensis as a precursor, and obtain a sodium ion hard carbon negative electrode material self-doped with N element through a simple and pollution-free preparation process. When applied to sodium ion batteries, the negative electrode material exhibits relatively excellent electrochemical properties.

[0005] In order to achieve the purpose, the present invention adopts the following technical scheme:

[0006] A method for preparing a phycocyanin-based pea-shaped hard carbon negative electrode material for a sodium ion battery, the specific steps are as follows:

[0007] 1) placing the phycocyanin in a muffle furnace and heating it to 200-250° C. at a heating rate of 2-5° C. / min, keeping the temperature for 4-8 hours in an air atmosphere, and then cooling it to room temperature with the furnace to obtain a first intermediate product;

[0008] 2) ball milling the first intermediate product for 0.25 to 1 h to obtain a second intermediate product;

[0009] 3) placing the second intermediate product in a tubular furnace, heating it to 1200-1500°C at a heating rate of 2-5°C / min in an inert gas atmosphere, keeping it warm for 2-4 hours, then cooling it to 40-60°C at a cooling rate of 2-5°C / min, and then cooling it to room temperature with the furnace to obtain a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material.

[0010] Furthermore, in the above technical solution, the phycocyanin in step 1) is extracted from Spirulina platensis.

[0011] Furthermore, in the above technical solution, in step 2), the ball-to-material ratio of the ball milling (ie, the mass ratio of the ball milling beads to the second intermediate to be ball milled) is 4-6:1.

[0012] Furthermore, in the above technical solution, in step 3), the inert gas is argon.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] 1. The preparation process is simple and suitable for large-scale production.

[0015] 2. The entire preparation process avoids the use of acid and alkali, reducing environmental pressure.

[0016] 3. The phycocyanin precursor can make the prepared hard carbon negative electrode material self-doped with N element, and a hard carbon negative electrode material with excellent performance can be obtained without the need for an additional N doping step. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the SEM image of the hard carbon negative electrode material for sodium ion battery prepared in Example 1.

[0018] Figure 2 This is the EDS spectrum of the hard carbon negative electrode material for sodium ion battery prepared in Example 1.

[0019] Figure 3 The first cycle charge and discharge curves of the sodium ion battery hard carbon negative electrode materials prepared in Examples 1-3 and Comparative Examples 1-3.

[0020] Figure 4 This is a long cycle performance diagram of the sodium ion battery hard carbon negative electrode material prepared in Example 1. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described and explained below in conjunction with embodiments, but these embodiments are not intended to limit the protection scope of the present invention.

[0022] Example 1

[0023] 1) Weigh 5 g of commercial phycocyanin extracted from Spirulina platensis, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 6 hours in an air atmosphere, and then cool it to room temperature with the furnace to obtain a first intermediate product.

[0024] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 0.5 h to obtain a second intermediate product.

[0025] 3) The second intermediate product is placed in a tubular furnace, heated to 1300°C at a heating rate of 3°C / min under an argon atmosphere, kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material product.

[0026] Figure 1 This is a SEM image of the sodium ion battery hard carbon negative electrode material prepared in Example 1. It can be seen that the hard carbon material presents a typical pea-shaped morphology.

[0027] Figure 2 This is the EDS spectrum of the hard carbon negative electrode material for sodium ion batteries prepared in Example 1. The results show that the C, O, and N elements are evenly distributed in the hard carbon material, and the N content is about 2.7%. The presence of the N element can increase the charge transfer capacity of the material and provide more active sites for the embedding of sodium ions.

[0028] Example 2

[0029] 1) Weigh 5 g of commercial phycocyanin extracted from Spirulina platensis, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 6 hours in an air atmosphere, and then cool it to room temperature with the furnace to obtain a first intermediate product.

[0030] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 0.5 h to obtain a second intermediate product.

[0031] 3) The second intermediate product is placed in a tubular furnace, heated to 1500°C at a heating rate of 3°C / min under an argon atmosphere, kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material product.

[0032] Example 3

[0033] 1) Weigh 5 g of commercial phycocyanin extracted from Spirulina platensis, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 8 h in an air atmosphere, and then cool it to room temperature with the furnace to obtain a first intermediate product.

[0034] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 1 h to obtain a second intermediate product.

[0035] 3) The second intermediate product is placed in a tubular furnace, heated to 1500°C at a heating rate of 3°C / min under an argon atmosphere, kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material product.

[0036] Comparative Example 1

[0037] 1) Weigh 5 g of commercial phycocyanin extracted from Spirulina platensis, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 6 hours in an air atmosphere, and then cool it to room temperature with the furnace to obtain a first intermediate product.

[0038] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 0.5 h to obtain a second intermediate product.

[0039] 3) The second intermediate product is placed in a tubular furnace, heated to 1100°C at a heating rate of 3°C / min under an argon atmosphere, then kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material product.

[0040] Comparative Example 2

[0041] 1) Weigh 5 g of commercial corn starch, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 6 hours in an air atmosphere, and then cool it to room temperature in the furnace to obtain a first intermediate product.

[0042] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 0.5 h to obtain a second intermediate product.

[0043] 3) The second intermediate product is placed in a tubular furnace, heated to 1300°C at a heating rate of 3°C / min under an argon atmosphere, kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a finished starch-based sodium ion battery hard carbon negative electrode material.

[0044] Comparative Example 3

[0045] 1) Weigh 5 g of commercial sucrose, place it in a muffle furnace and heat it to 230° C. at a heating rate of 3° C. / min, keep it warm for 6 hours in an air atmosphere, and then cool it to room temperature in the furnace to obtain a first intermediate product.

[0046] 2) Weigh 2 g of the first intermediate product and 10 g of ball milling beads, and use a ball mill to perform ball milling for 0.5 h to obtain a second intermediate product.

[0047] 3) The second intermediate product is placed in a tubular furnace, heated to 1300°C at a heating rate of 3°C / min under an argon atmosphere, kept warm for 3 hours, then cooled to 50°C at a cooling rate of 3°C / min and then cooled to room temperature with the furnace, finally obtaining a finished product of a sucrose-based sodium ion battery hard carbon negative electrode material.

[0048] The sodium ion battery hard carbon negative electrode material obtained in the above examples and comparative examples, carbon black, and sodium carboxymethyl cellulose were added to deionized water in a mass ratio of 8:1:1 and stirred for 1 hour. The obtained slurry was then applied to the surface of the copper current collector with a scraper, and finally placed in a forced air drying oven for 8 hours before being beaten into an electrode sheet with a diameter of 14 mm. The obtained electrode sheet was used as the working electrode and the sodium sheet as the counter electrode. The CR2032 button battery was assembled in an argon-filled glove box. The diaphragm used was glass fiber, and the electrolyte was a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution. The electrochemical test was carried out on a Xinwei CT-4008 tester, and the charge and discharge voltage range was 0.01 to 3V.

[0049] Figure 3 The first cycle charge and discharge curves of the hard carbon negative electrode materials for sodium ion batteries prepared in Examples 1-3 and Comparative Examples 1-3. As can be seen from the figure, the hard carbon negative electrode materials of Examples 1, 2 and 3 exhibited relatively high first cycle coulombic efficiencies (85.0%, 84.0% and 83.7%, respectively), while the coulombic efficiencies of the comparative examples were relatively low (74.7%, 78.9% and 73.1%, respectively). The higher coulombic efficiencies of Examples 1-3 indicate that irreversible sodium consumption caused by defects, side reactions, etc. is relatively small.

[0050] Figure 4 This is a long cycle performance diagram of the hard carbon negative electrode material for sodium ion batteries prepared in Example 1. It can be found that at a current density of 150 mA / g, the hard carbon material still has a reversible capacity of 265 mAh / g after 200 cycles, and the capacity retention rate is as high as 95.5%, indicating that the hard carbon negative electrode material for sodium ion batteries has good cycle stability.

[0051] The above embodiments are only preferred embodiments of the present invention, and are intended to illustrate the technical concept and features of the present invention, and are not intended to limit the present invention. It should be noted that any simple deformation, replacement and improvement made according to the spirit of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a phycocyanin-based pea-shaped hard carbon negative electrode material for sodium ion batteries, characterized in that: The following steps are involved: 1) placing the phycocyanin in a muffle furnace and heating it to 200-250° C. at a heating rate of 2-5° C. / min, keeping the temperature for 4-8 hours in an air atmosphere, and then cooling it to room temperature with the furnace to obtain a first intermediate product; 2) ball milling the first intermediate product for 0.25 to 1 h to obtain a second intermediate product; 3) placing the second intermediate product in a tubular furnace, heating it to 1200-1500°C at a heating rate of 2-5°C / min in an inert gas atmosphere, keeping it warm for 2-4 hours, then cooling it to 40-60°C at a cooling rate of 2-5°C / min, and then cooling it to room temperature with the furnace to obtain a phycocyanin-based pea-shaped sodium ion battery hard carbon negative electrode material.

2. The method for preparing a phycocyanin-based pea-shaped hard carbon negative electrode material for sodium ion batteries according to claim 1, characterized in that: The phycocyanin in step 1) is extracted from Spirulina platensis.

3. The method for preparing a phycocyanin-based pea-shaped hard carbon negative electrode material for sodium ion batteries according to claim 1, characterized in that: In step 2), the ball-to-material ratio of the ball mill is 4 to 6:

1.

4. The method for preparing a phycocyanin-based pea-shaped hard carbon negative electrode material for sodium ion batteries according to claim 1, characterized in that: In step 3), the inert gas is argon.

5. A phycocyanin-based pea-shaped hard carbon negative electrode material for sodium ion batteries, characterized in that: The method according to any one of claims 1 to 4 is prepared.

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