A method for preparing and applying a papermaking black liquor-based hard carbon anode.

Abstract

This invention relates to the field of sodium-ion battery technology, and more particularly to a method for preparing and applying a papermaking black liquor-based hard carbon anode. The method includes the following steps: (1) drying and pulverizing the papermaking black liquor to obtain papermaking black liquor powder; (2) calcining the papermaking black liquor powder at high temperature to obtain black liquor carbon powder; (3) acid washing and alkali washing of the black liquor carbon powder to remove impurities, followed by water washing until neutral; (4) tempering the impurity-removed black liquor carbon powder at high temperature to obtain hard carbon powder. In this invention, sodium, potassium, iron, and other metal salts in the papermaking black liquor can be uniformly distributed in the black liquor carbon during calcination, acting as pore-forming agents, effectively increasing the porosity of the porous carbon and providing abundant sodium storage sites for sodium ions. Simultaneously, heteroatom doping can effectively improve conductivity and increase the capacity of the hard carbon anode.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and more particularly to a method for preparing and applying a papermaking black liquor-based hard carbon anode. Background Technology

[0002] Lithium-ion batteries are currently the preferred commercial battery, but the scarcity and high price of lithium resources limit their development. Sodium-ion batteries, due to their lower cost and abundant sodium reserves, have become a research hotspot in recent years. However, sodium-ion batteries have a lower energy density, making them a preferred option for future energy storage. They have broad application prospects in the utilization of renewable energy sources such as wind, solar, and tidal power, which are limited by location and time, and also have potential applications in grid peak shaving and energy storage power stations. In conclusion, the development of high-performance sodium-ion batteries is of great significance to the future development of the energy storage field.

[0003] The rapid development of sodium-ion batteries has increased the demand for hard carbon anodes, necessitating the development of high-performance hard carbon anode materials. Currently, hard carbon anode precursor materials mainly include biomass-based, polymer-based, resin-based, and coal-based carbon materials. These materials require complex steps such as crushing, ball milling, and calcination to obtain hard carbon anode powder. Furthermore, to improve performance, modification steps such as pore formation and heteroatom doping are necessary, increasing the complexity of the hard carbon anode preparation process and resulting in poor product uniformity and batch consistency. Therefore, developing a more stable precursor and a simpler preparation method is of great significance for the preparation of hard carbon anodes. Summary of the Invention

[0004] To address the complex preparation process of biomass hard carbon precursors, this invention provides a method for preparing and applying a papermaking black liquor-based hard carbon anode. By utilizing the organic matter, alkaline substances, and nitrogen, sulfur, and phosphorus compounds contained in papermaking black liquor, the method enables the controllable preparation of porous heteroatom-doped hard carbon anodes, resulting in high-performance sodium-ion battery hard carbon anode materials. This solves the pollution problem of papermaking black liquor and enables its high-value utilization.

[0005] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing a papermaking black liquor-based hard carbon anode, the method comprising the following steps:

[0007] (1) Dry the papermaking black liquor and then pulverize it to obtain papermaking black liquor powder;

[0008] (2) The black liquor powder of papermaking is calcined at high temperature to obtain black liquor carbon powder;

[0009] (3) The black liquor and carbon powder are acid-washed and alkali-washed to remove impurities, and then washed with water until neutral.

[0010] (4) The black liquor carbon powder after impurity removal is subjected to high-temperature tempering to obtain hard carbon powder.

[0011] Preferably, in step (1), the drying temperature is 80-150℃ and the drying time is 5-15h.

[0012] Preferably, in step (2), the calcination temperature is 800-1600℃ and the calcination time is 2-20h.

[0013] Preferably, in step (3), the acid used for pickling is one or a combination of sulfuric acid, hydrochloric acid, and nitric acid, and the alkali used for alkaline washing is one of sodium hydroxide and potassium hydroxide.

[0014] Preferably, in step (4), the tempering temperature is 600-1000℃ and the tempering time is 2-10h.

[0015] Preferably, the hard carbon powder has a particle size of 0.5-100 μm.

[0016] Another aspect of the present invention provides the application of the hard carbon anode prepared by the above-described method in a sodium-ion battery.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention discloses a method for preparing and applying a papermaking black liquor-based hard carbon anode. The method involves drying and pulverizing papermaking black liquor to obtain black liquor powder, followed by calcination, acid washing, alkali washing, and tempering to convert the papermaking black liquor into a high-value hard carbon anode for sodium-ion batteries. On one hand, the organic matter such as cellulose, lignin, and hemicellulose present in papermaking black liquor can serve as a carbon source, yielding hard carbon powder after high-temperature calcination. On the other hand, metal salts such as sodium, potassium, and iron in papermaking black liquor can be uniformly distributed in the black liquor carbon during calcination, acting as pore-forming agents to effectively increase the porosity of the porous carbon and provide abundant sodium storage sites for sodium ions. Simultaneously, heteroatom doping effectively improves conductivity and increases the capacity of the hard carbon anode. This invention effectively solves the pollution problem of papermaking black liquor, while simultaneously achieving high-value utilization of papermaking black liquor and reducing battery costs. Attached Figure Description

[0019] Figure 1 The image shows a scanning electron microscope (SEM) image of the sample prepared in Comparative Example 1.

[0020] Figure 2 The circuit efficiency graph is shown for the sample prepared in Comparative Example 1.

[0021] Figure 3 The image shown is a scanning electron microscope image of the sample prepared in Example 1.

[0022] Figure 4 The circuit efficiency graph of the sample prepared in Example 1;

[0023] Figure 5 The image shown is a scanning electron microscope image of the sample obtained in Example 2.

[0024] Figure 6 The circuit efficiency graph of the sample obtained in Example 2;

[0025] Figure 7 The image shown is a scanning electron microscope image of the sample obtained in Example 3.

[0026] Figure 8 The image shows the cycle efficiency of the sample prepared in Example 3. Detailed Implementation

[0027] The present invention will now be described in detail through specific embodiments.

[0028] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0029] Comparative Example 1

[0030] (1) Use a pulverizer to pulverize the dried coconut shells to obtain fine coconut shell powder;

[0031] (2) Coconut shell powder was calcined in a tube furnace at 900°C under a nitrogen atmosphere for 10 hours to obtain coconut shell carbon powder.

[0032] (3) The obtained coconut shell carbon powder was acid-washed with hydrochloric acid, centrifuged, washed with sodium hydroxide, centrifuged, and washed with deionized water until pH=7.

[0033] (4) The treated coconut shell carbon powder was calcined in a tube furnace at 800°C for 5 hours and then ball-milled to obtain hard carbon powder.

[0034] like Figure 1 As shown, the hard carbon powder prepared in Comparative Example 1 has an irregular shape, with a particle size distribution mainly concentrated in the range of 50-300 μm and a specific surface area of ​​20 m². 2 / g, pore size distribution is 500nm-1μm. For example... Figure 2 As shown, the initial coulombic efficiency is 68%, the initial capacity is 250 mAh / g, and it decays to 150 mAh / g after 300 cycles.

[0035] Example 1

[0036] (1) The black liquor of papermaking was dried in a blower oven at 80°C for 15 hours. After drying, the resulting solid product was crushed and ground to obtain black liquor powder.

[0037] (2) The black liquor powder was calcined in a tube furnace at 900°C under a nitrogen atmosphere for 10 hours to obtain black liquor carbon powder.

[0038] (3) The obtained black liquor carbon powder was acid-washed with hydrochloric acid, centrifuged, alkaline-washed with sodium hydroxide, centrifuged, and washed with deionized water until pH=7, and then dried.

[0039] (4) The treated black liquor carbon powder was calcined in a tube furnace at 800°C for 5 hours and then ball-milled to obtain hard carbon powder.

[0040] like Figure 3 As shown, the hard carbon powder prepared in Example 1 has an irregular shape, with a particle size distribution mainly concentrated in the range of 10-100 μm and a specific surface area of ​​500 m². 2 / g, pore size distribution is 2-10nm. For example... Figure 4 As shown, the initial coulombic efficiency was 86%, and the capacity stabilized at 300 mAh / g.

[0041] Example 2

[0042] (1) The black liquor of papermaking is dried in a blower oven at 100°C for 10 hours. After drying, the resulting solid product is crushed and ground to obtain black liquor powder.

[0043] (2) The black liquor carbon powder was calcined in a tube furnace at 1200°C under a nitrogen atmosphere for 10 hours to obtain black liquor carbon powder.

[0044] (3) The obtained black liquor carbon powder was acid-washed with sulfuric acid, filtered, alkaline-washed with potassium hydroxide, filtered, and washed with deionized water until pH=7, and then dried.

[0045] (4) The treated black liquor carbon powder was calcined in a tube furnace at 800°C for 15 hours and then ball-milled to obtain hard carbon powder.

[0046] like Figure 5 As shown, the prepared hard carbon powder has an irregular shape, with a particle size distribution mainly concentrated in the range of 10-80 μm and a specific surface area of ​​350 m². 2 / g, pore size distribution is 5-15nm. For example... Figure 6 As shown, the initial coulombic efficiency was 85%, and the capacity stabilized at 330 mAh / g.

[0047] Example 3

[0048] (1) The papermaking black liquor was dried in a forced-air drying oven at 120°C for 5 hours. After drying, the resulting solid product was crushed and ground to obtain black liquor powder.

[0049] (2) The black liquor powder was calcined in a tube furnace at 1600°C under a nitrogen atmosphere for 10 hours to obtain black liquor carbon powder.

[0050] (3) The obtained black liquor carbon powder was acid-washed with nitric acid, filtered, alkaline-washed with sodium hydroxide, filtered, and washed with deionized water until pH=7, and then dried.

[0051] (4) The treated black liquor carbon powder was calcined in a tube furnace at 800°C for 5 hours and then ball-milled to obtain hard carbon powder.

[0052] like Figure 7 As shown, the prepared hard carbon powder has an irregular shape, with a particle size distribution mainly concentrated in the range of 10-50 μm and a specific surface area of ​​150 m². 2 / g, pore size distribution is 10-20nm. For example... Figure 8 As shown, the initial coulombic efficiency was 90%, and the capacity stabilized at 300 mAh / g.

[0053] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. Use of a hard carbon negative electrode in a sodium-ion battery, characterized in that, The preparation method of the hard carbon negative electrode comprises the following steps: (1) drying and crushing papermaking black liquor to obtain papermaking black liquor powder; (2) high-temperature calcining the papermaking black liquor powder to obtain black liquor carbon powder; (3) acid washing and alkali washing the black liquor carbon powder to remove impurities, and washing to neutral; (4) high-temperature tempering the black liquor carbon powder after impurity removal to obtain hard carbon powder; In step (2), the calcining temperature is 800-1600℃, and the calcining time is 2-20h; In step (4), the tempering temperature is 600-1000℃, and the tempering time is 2-10h.

2. Use according to claim 1, characterized in that, In step (1), the drying temperature is 80-150℃, and the time is 5-15h.

3. Use according to claim 1, characterized in that, In step (3), the acid used for acid washing is one or a combination of several of sulfuric acid, hydrochloric acid and nitric acid, and the alkali used for alkali washing is one of sodium hydroxide and potassium hydroxide.

4. Use according to claim 1, characterized in that, The particle size of the hard carbon powder is 0.5-100μm.

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