Roller hearth furnace for sintering hard carbon anode of sodium-ion battery

Abstract

The present invention discloses a roller furnace for sintering hard carbon negative electrodes of sodium ion batteries, comprising a roller furnace body, the starting section and the ending section of the roller furnace body are respectively provided with a purification mechanism and an active impurity removal mechanism; the active impurity removal mechanism comprises a discharge stage and a dust collecting stage, the discharge stage comprises a plurality of horizontal and equidistantly arranged pole plates, and the arrangement direction of the pole plates is parallel to the direction of material travel, the dust collecting stage is vertically arranged at the top of the discharge stage and its width matches the width of the furnace chamber of the roller furnace body, the cavity of the dust collecting stage is vertically connected and the horizontal cross section is honeycomb-shaped, and a second gas collecting hopper is arranged at the top of the dust collecting stage; the air purified by the purification mechanism output by the gas transmission pipe is uniformly blown to the outer surface of the material after being pressurized by the dust collecting stage and diverted by the discharge stage. The present invention can not only remove dust and purify the air in the starting section of the roller furnace body and the hard carbon surface, but also clean the oxides and carbonization reactants attached to the surface after the hard carbon is sintered, thereby improving the quality and performance of the hard carbon negative electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of roller hearth furnaces, and particularly relates to a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries. Background Art

[0002] With the rapid development of electric vehicles and energy storage systems, sodium-ion batteries, as a potential alternative to lithium-ion batteries, have received extensive attention. Sodium-ion batteries have the advantages of rich raw material resources and low cost, and show strong application potential in the fields of large-scale energy storage and electric transportation. Among the anode materials of sodium-ion batteries, hard carbon has become the research focus of sodium-ion battery anode materials due to its excellent electrochemical performance and good cycle stability.

[0003] During the preparation process of hard carbon anode materials, the sintering process is one of the key steps affecting their performance. The sintering process not only determines the structure and morphology of hard carbon materials, but also directly affects their electrochemical performance. However, during the sintering process of hard carbon anode materials, the presence of dust and environmental pollutants has an adverse effect on the sintering effect. Dust particles will adhere to the surface of hard carbon or react with hard carbon, resulting in uneven surface, structural defects or reduced performance, thus affecting the efficiency and stability of the battery.

[0004] In addition, hard carbon materials often form oxides and carbides on the surface during high-temperature heat treatment. These oxides and carbides will interact with the hard carbon matrix, thereby affecting the electrochemical performance of the materials. For example, the formation of oxides will lead to a decrease in the surface conductivity of the materials, while the formation of carbides causes the loss of surface active sites, thus affecting the charge-discharge performance and cycle life of the battery. Therefore, how to effectively control the dust pollution before sintering and the oxides and carbide reaction products attached to the surface after sintering has become a key issue in improving the quality and performance of hard carbon anode materials. Summary of the Invention

[0005] The present invention proposes the following technical solutions for the problems in the prior art:

[0006] A roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries, comprising a roller hearth furnace body, the roller hearth furnace body includes a starting section, a sintering section and an ending section, and a purification mechanism and an active impurity removal mechanism are respectively arranged at the starting section and the ending section of the roller hearth furnace body;

[0007] The purification mechanism includes a filtration component and a circulation component, and the circulation component acts on the air in the starting section of the roller hearth furnace body, and is purified by the filtration component and then transported to the active impurity removal mechanism;

[0008] The active impurity removal mechanism includes an impurity removal component and a cold filtration component. The impurity removal component includes a discharge stage and a dust collection stage disposed at the end section of the roller hearth furnace main body. The discharge stage includes a plurality of horizontally and equidistantly arranged electrode plates, and the arrangement direction of the electrode plates is parallel to the material traveling direction. The dust collection stage is vertically disposed on top of the discharge stage and has a width matching the width of the furnace cavity of the roller hearth furnace main body. The cavity of the dust collection stage is vertically through and its horizontal cross-section is honeycomb-shaped. A second air collecting hopper is provided at the top of the dust collection stage;

[0009] The purification mechanism and the active impurity removal mechanism are connected and communicated through an air delivery pipe. The output end of the air delivery pipe extends to the top of the furnace cavity of the roller hearth furnace main body. The air purified by the purification mechanism output by the air delivery pipe is evenly blown to the outer surface of the material after being pressurized by the dust collection stage and shunted by the discharge stage.

[0010] As a preference of the above technical solution, the roller hearth furnace main body includes conveying rollers, atmosphere pipes, and two partition plates, and the two partition plates are located at both ends of the sintering section.

[0011] As a preference of the above technical solution, the filtration component includes an upper filtration box and a lower filtration box disposed on the top of the roller hearth furnace main body. A plurality of filter meshes are detachably installed inside the upper filtration box and the lower filtration box, and the filter diameters of the plurality of filter meshes decrease in sequence. The head ends of the filter meshes are fixedly connected with handles.

[0012] As a preference of the above technical solution, the circulation component includes an air inlet pipe interconnected on one side of the upper filtration box and a third through pipe interconnected on one side of the lower filtration box, and the air inlet pipe and the third through pipe are close to the filter mesh with the largest filter diameter. The other end of the third through pipe is interconnected with a first air collecting hopper, and the first air collecting hopper is fixedly connected to the side wall of the starting section of the roller hearth furnace main body;

[0013] A first air pump and a second air pump are provided on the top of the roller hearth furnace main body. The input end of the first air pump is connected and communicated with the upper filtration box through a first through pipe, and the input end of the second air pump is connected and communicated with the lower filtration box through a fourth through pipe, and the first through pipe and the fourth through pipe are respectively arranged oppositely to the air inlet pipe and the third through pipe.

[0014] As a preference of the above technical solution, an air supply hopper is fixedly connected to the top wall of the furnace cavity at the starting section of the roller hearth furnace main body, and the air outlet of the air supply hopper is inclined downward and points to the starting section of the roller hearth furnace main body;

[0015] The output end of the first air pump is interconnected with a second through pipe, and the bottom end of the second through pipe is connected to the top of the air supply hopper.

[0016] As a preference of the above technical solution, one end of the air delivery pipe is connected to the output end of the second air pump, and the other end of the air delivery pipe extends to the top of the furnace cavity of the roller hearth furnace main body and is in a conical hopper shape.

[0017] As an optimization of the above technical solution, the impurity removal component further includes a power supply unit disposed on the top of the roller hearth furnace body, and the power supply unit is electrically connected to the discharge stage and the dust collection stage;

[0018] The power supply unit includes a high-voltage power supply, a transformer, and a rectifier.

[0019] As an optimization of the above technical solution, the impurity removal component further includes a third air pump disposed on the top of the roller hearth furnace body, and the input end of the third air pump is connected to the top of the second air collecting hopper through a fifth connecting pipe.

[0020] As an optimization of the above technical solution, the cold filtration component includes a cold filtration box disposed on the top of the roller hearth furnace body. The output end of the third air pump is interconnected with a sixth connecting pipe, and the tail end of the sixth connecting pipe penetrates into the cold filtration box from the top and extends to the bottom of the cold filtration box;

[0021] The outside of the cold filtration box is interconnected with a liquid inlet pipe, a liquid outlet pipe, and a gas outlet pipe.

[0022] As an optimization of the above technical solution, the gas outlet pipe and the gas inlet pipe are connected through a pipeline.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. In the present invention, the purification mechanism can not only remove dust and purify the air at the starting section of the roller hearth furnace body and the surface of the hard carbon, reducing the dust and environmental pollutants adhering to the surface of the hard carbon before sintering, but also can perform secondary purification after recycling the air, and convey the clean air to the active impurity removal mechanism. The active impurity removal mechanism can clean the surface of the sintered hard carbon, eliminating the oxides and carbonized reaction products adhering to the surface of the hard carbon after sintering, and improving the quality and performance of the hard carbon negative electrode material;

[0025] 2. In the present invention, the width of the dust collection stage matches the width of the furnace cavity of the roller hearth furnace body, reducing the radial ventilation area of the furnace cavity of the roller hearth furnace body, so that the air blown into the furnace cavity of the roller hearth furnace body by the air delivery pipe is pressurized and blown into the gaps between multiple electrode plates, and the multiple electrode plates evenly divide the pressurized blown air and blow it to the outer surface of the material, thereby achieving a better cleaning effect on the oxides and carbonized reaction products adhering to the surface of the hard carbon after sintering;

[0026] 3. The sintered hard carbon is accompanied by a large amount of heat. Based on the principle of hot air rising, a second air collecting hopper is arranged at the top of the dust collection stage, which can avoid the air and the oxides and carbonized reaction products carried in the air from running out of the side outlet at the end of the roller hearth furnace body to a greater extent; at the same time, the power supply unit, the discharge stage, and the dust collection stage work, and the air containing oxides and carbonized reaction products is ionized through a high-voltage electric field, so that the oxide and carbonized reaction product particles are negatively charged and adsorbed onto the dust collection stage to be collected; at the same time, the design of the dust collection stage cavity being vertically through and having a honeycomb-shaped horizontal cross-section can better adsorb the oxide and carbonized reaction product particles;

[0027] 4. During the process of the active impurity removal mechanism removing oxides and carbide reaction products, the air flow also takes away the heat after hard carbon sintering, thus achieving the effect of active cooling. When it is necessary to clean the oxides and carbide reaction products attached to the dust collection stage, the power supply unit can be powered off, while maintaining the air delivery of the air delivery pipe and the operation of the third air pump. In this way, the air passing through the dust collection stage will transport the attached oxides and carbide reaction products to the cold filter box, making the operation more convenient;

[0028] 5. After the air outlet pipe and the air inlet pipe are connected through a pipeline and cooperate with the air delivery pipe, an air circuit cycle is formed between the purification mechanism and the active impurity removal mechanism, further improving the air purification effect at the starting section of the roller hearth furnace body and the purification effect of the surface attachments after hard carbon sintering; at the same time, it also reduces the exchange with the external air of the roller hearth furnace body, ensuring the stability of the purification of the purification mechanism and the active impurity removal mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. shows a three-dimensional structural schematic diagram of a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries in an embodiment;

[0030] Figure 2 FIG. shows Figure 1 an enlarged view of part A in;

[0031] Figure 3 FIG. shows a three-dimensional structural schematic diagram of a purification mechanism in a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries in an embodiment;

[0032] Figure 4 FIG. shows a sectional view of the internal structure of the roller hearth furnace body in a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries in an embodiment;

[0033] Figure 5 FIG. shows a three-dimensional structural schematic diagram of a discharge stage and a dust collection stage in a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries in an embodiment;

[0034] Figure 6 FIG. shows a schematic diagram of the internal structure of a cold filter box in a roller hearth furnace for sintering hard carbon anodes of sodium-ion batteries in an embodiment.

[0035] In the figure: 10. Roller hearth furnace body; 11. Conveyor roller; 12. Partition board; 13. Atmosphere pipe;

[0036] 20. Purification mechanism; 21. Filtration component; 22. Circulation component; 211. Upper filtration box; 212. Lower filtration box; 213. Filter screen; 214. Handle; 221. Intake pipe; 222. First through pipe; 223. First air pump; 224. Second through pipe; 225. Air delivery hopper; 226. First air collection hopper; 227. Third through pipe; 228. Fourth through pipe; 229. Second air pump;

[0037] 30. Gas transmission pipe;

[0038] 41. Impurity removal component; 42. Cold filtration component; 411. Power supply unit; 412. Discharge electrode; 413. Dust collection electrode; 414. Second air collection hopper; 415. Fifth through pipe; 416. Third air pump; 421. Sixth through pipe; 422. Cold filtration box; 423. Liquid inlet pipe; 424. Liquid outlet pipe; 425. Air outlet pipe. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0040] Embodiment; As Figure 1 shown, a roller hearth furnace for sintering the hard carbon negative electrode of a sodium ion battery includes a roller hearth furnace body 10. The roller hearth furnace body 10 includes a starting section, a sintering section and an ending section. A purification mechanism 20 and an active impurity removal mechanism are respectively arranged at the starting section and the ending section of the roller hearth furnace body 10. The purification mechanism 20 includes a filtration component 21 and a circulation component 22. The circulation component 22 acts on the air at the starting section of the roller hearth furnace body 10, and after being purified by the filtration component 21, it is transported to the active impurity removal mechanism. In the present invention, the material (i.e., hard carbon) enters from the starting section of the roller hearth furnace body 10, then undergoes calcination in the sintering section, and is sent out from the ending section after sintering. In the present invention, the purification mechanism 20 can not only remove dust and purify the air at the starting section of the roller hearth furnace body 10 and the surface of the hard carbon, reduce the dust and environmental pollutants attached to the surface of the hard carbon before sintering, but also can be secondarily purified after recycling the air, and transport the clean air to the active impurity removal mechanism. The active impurity removal mechanism can clean the surface of the sintered hard carbon, eliminate the oxides and carbonized reaction products attached to the surface of the hard carbon after sintering, and improve the quality and performance of the hard carbon negative electrode material.

[0041] As Figure 2 , Figure 3 , Figure 4As shown, the filtering component 21 includes an upper filtering box 211 and a lower filtering box 212 arranged at the top of the roller hearth furnace body 10. A plurality of filter meshes 213 are detachably installed inside the upper filtering box 211 and the lower filtering box 212. The filter diameters of the plurality of filter meshes 213 decrease in sequence. The head ends of the filter meshes 213 are fixedly connected with handles 214; the circulating component 22 includes an air inlet pipe 221 interconnected on one side of the upper filtering box 211 and a three-way pipe 227 interconnected on one side of the lower filtering box 212. The air inlet pipe 221 and the three-way pipe 227 are close to the filter mesh 213 with the largest filter diameter. The other end of the three-way pipe 227 is interconnected with a first air collecting hopper 226, and the first air collecting hopper 226 is fixedly connected to the side wall of the starting section of the roller hearth furnace body 10; a first air pump 223 and a second air pump 229 are arranged at the top of the roller hearth furnace body 10. The input end of the first air pump 223 is communicated with the upper filtering box 211 through a first pipe 222, and the input end of the second air pump 229 is communicated with the lower filtering box 212 through a fourth pipe 228. The first pipe 222 and the fourth pipe 228 are respectively arranged oppositely to the air inlet pipe 221 and the three-way pipe 227; a gas supply hopper 225 is fixedly connected to the top wall of the furnace cavity at the starting section of the roller hearth furnace body 10. The air outlet of the gas supply hopper 225 is arranged obliquely downward and points to the starting section of the roller hearth furnace body 10; the output end of the first air pump 223 is interconnected with a second pipe 224, and the bottom end of the second pipe 224 is communicated with the top of the gas supply hopper 225.

[0042] The working principle of the purification mechanism 20 is as follows: When the first air pump 223 operates, under the connection of the first connecting pipe 222, the air inside the upper filter box 211 is extracted, creating a negative pressure inside it. Under the action of the negative pressure, air enters the upper filter box 211 from the air inlet pipe 221, passes through multiple filter meshes 213 for filtration and purification, and then is transported to the air supply hopper 225 through the second connecting pipe 224. In the present invention, the filtration diameters of the multiple filter meshes 213 decrease in sequence. The air inlet pipe 221 is close to the filter mesh 213 with the largest filtration diameter, and the air inlet pipe 221 and the first connecting pipe 222 are arranged oppositely. In this way, the air entering the inner cavity of the upper filter box 211 from the air inlet pipe 221 will be gradually purified and dust-removed by the multiple filter meshes 213, with good dust-removing effect and high air filtration efficiency. In the present invention, the filter mesh 213 is designed to be detachable, and the staff can replace or clean the filter mesh 213 through the handle 214, making daily use more convenient. The air outlet of the air supply hopper 225 is inclined downward and points to the starting section of the roller hearth furnace main body 10. In this way, the air transported to the air supply hopper 225 can blow onto the surface of the hard carbon at the starting section of the roller hearth furnace main body 10, blowing the dust attached to its surface and the surrounding air out of the side opening of the furnace cavity of the roller hearth furnace main body 10. At the same time, when the second air pump 229 operates, under the connection of the fourth connecting pipe 228, a negative pressure is similarly generated inside the lower filter box 212. Under the connection of the third connecting pipe 227, a negative pressure is further generated in the first air collecting hopper 226. In this way, the air blown out of the side opening of the furnace cavity of the roller hearth furnace main body 10 is re-sucked into the inner cavity of the lower filter box 212 by the first air collecting hopper 226. Similarly, after being secondary-purified by the multi-stage filtration and dust-removal of the filter mesh 213 in the inner cavity of the lower filter box 212, it is transported to the active impurity removal mechanism through the air delivery pipe 30.

[0043] As Figure 1 、 Figure 4 shown, one end of the air delivery pipe 30 is connected to the output end of the second air pump 229, and the other end of the air delivery pipe 30 extends to the top of the furnace cavity of the roller hearth furnace main body 10 and is in a conical hopper shape. The conical hopper shape design can make the secondary-purified air blow more evenly into the furnace cavity at the end section of the roller hearth furnace main body 10, and the air outlet of the conical hopper is in an inclined setting similar to that of the air supply hopper 225, making its blowing direction face the surface of the sintered hard carbon.

[0044] As Figure 1 、 Figure 4 、 Figure 5As shown in the figure, the active impurity removal mechanism includes an impurity removal component 41 and a cold filtration component 42. The impurity removal component 41 includes a discharge stage 412 and a dust collection stage 413 placed at the end section of the roller hearth furnace body 10. The discharge stage 412 includes a plurality of horizontally and equidistantly arranged electrode plates, and the arrangement direction of the electrode plates is parallel to the material traveling direction. The dust collection stage 413 is vertically arranged on the top of the discharge stage 412 and has a width matching the width of the furnace cavity of the roller hearth furnace body 10. The cavity of the dust collection stage 413 is vertically penetrated and its horizontal cross-section is honeycomb-shaped. A second air collection hopper 414 is arranged at the top of the dust collection stage 413; the impurity removal component 41 further includes a power supply unit 411 arranged on the top of the roller hearth furnace body 10, and the power supply unit 411 is electrically connected to the discharge stage 412 and the dust collection stage 413; the power supply unit 411 includes a high-voltage power supply, a transformer, and a rectifier; the impurity removal component 41 further includes a third air pump 416 arranged on the top of the roller hearth furnace body 10, and the input end of the third air pump 416 is connected to the top of the second air collection hopper 414 through a fifth connecting pipe 415.

[0045] In the present invention, the dust collection stage 413 is placed in the furnace cavity of the roller hearth furnace body 10 and has a width matching the width of the furnace cavity of the roller hearth furnace body 10. In this way, the radial ventilation area of the furnace cavity of the roller hearth furnace body 10 is reduced, so that the air blown into the furnace cavity of the roller hearth furnace body 10 by the air delivery pipe 30 is pressurized and blown into the gaps between the plurality of electrode plates. The plurality of horizontally and equidistantly arranged electrode plates evenly divide the pressurized blown air, and thus evenly blow it to the outer surface of the material, so as to have a better cleaning effect on the oxides and carbonized reaction products adhering to the surface after the hard carbon sintering.

[0046] Meanwhile, the hard carbon after sintering is accompanied by a large amount of heat. Based on the principle of hot air rising, a second air collecting hopper 414 is arranged at the top of the dust collecting stage 413 and is connected to the third air pump 416 through a fifth connecting pipe 415. In this way, when the third air pump 416 operates, a negative pressure is generated in the second air collecting hopper 414, which absorbs air and the oxides and carbonization reactants attached to the air upward. Moreover, the second air collecting hopper 414, the discharge stage 412, and the dust collecting stage 413 have a certain length in the axial direction of the roller hearth furnace body 10, which can avoid air and the oxides and carbonization reactants attached to the air from running out of the side outlet at the end of the roller hearth furnace body 10 to a greater extent. At the same time, when the power supply unit 411, the discharge stage 412, and the dust collecting stage 413 operate, the air containing oxides and carbonization reactants is ionized through a high-voltage electric field, and the oxides and carbonization reactants in the air flow are separated from the air flow under the action of the electric field after being charged. In the strong electric field, they are ionized into positive ions and electrons. When the electrons run towards the dust collecting stage 413, they encounter the oxide and carbonization reactant particles, making the oxide and carbonization reactant particles negatively charged and adsorbed onto the dust collecting stage 413 to be collected. The design that the cavity of the dust collecting stage 413 is vertically through and the horizontal cross-section is honeycomb-shaped can better adsorb the oxide and carbonization reactant particles. It should be noted here that: when the hard carbon material undergoes heat treatment, especially at high temperatures, some oxides and carbides often form on the surface. Specifically, common ones include iron oxides such as Fe 3 O 4 or other iron-based compounds. These substances will adhere to the surface of the hard carbon. At the same time, these substances have certain particle sizes and charge characteristics. Because of their large inertia, they are easily affected by the electric field force and are more easily electrostatically adsorbed. Therefore, the dust collecting stage 413 has a better effect of adsorbing and removing oxides and carbonization reactants. During the process of removing oxides and carbonization reactants, the air flow also takes away the heat after the hard carbon is sintered, thus playing an active role in cooling. When it is necessary to clean the oxides and carbonization reactants attached to the dust collecting stage 413, the power supply unit 411 can be powered off, and at the same time, the air delivery of the air delivery pipe 30 and the operation of the third air pump 416 are maintained. In this way, the air passing through the dust collecting stage 413 will transport the oxides and carbonization reactants attached to it to the cold filter box 422.

[0047] As Figure 6 shown, the cold filter assembly 42 includes a cold filter box 422 arranged on the top of the roller hearth furnace body 10. The output end of the third air pump 416 is interconnected with a sixth connecting pipe 421, and the tail end of the sixth connecting pipe 421 penetrates into the cold filter box 422 from the top and extends to the bottom of the cold filter box 422. The outside of the cold filter box 422 is interconnected with a liquid inlet pipe 423, a liquid outlet pipe 424, and an air outlet pipe 425.

[0048] As described above, when the active impurity removal mechanism works, the air flow also takes away the heat after the hard carbon sintering. The hot air is formed and transported to the bottom of the cold filter box 422 through the sixth pipe 421. There is a heat dissipation liquid inside the cold filter box 422, and water is used in this embodiment. In this way, the hot air can be cooled down and then discharged from the air outlet pipe 425. At the same time, when the flowing air cleans the oxide and carbide reaction product particles attached to the dust collection stage 413, the oxide and carbide reaction product particles doped in the air will be filtered by water, and clean air is discharged from the air outlet pipe 425. By setting the liquid inlet pipe 423 and the liquid outlet pipe 424, the water inside the cold filter box 422 can form a water cycle, so as to ensure the cooling effect on the hot air and the filtering effect on the oxide and carbide reaction product particles.

[0049] As Figure 4 shown, the roller hearth furnace main body 10 includes conveying rollers 11, atmosphere pipes 13 and two partition plates 12, and the two partition plates 12 are located at both ends of the sintering section.

[0050] By setting the partition plates 12, the function of heat preservation for the sintering section of the roller hearth furnace main body 10 can be achieved, heat loss can be reduced, the atmosphere of the sintering section can be better controlled at the same time, and the mixing of external air into the sintering section can be reduced, ensuring the sintering quality.

[0051] As Figure 1 shown, the air outlet pipe 425 and the air inlet pipe 221 are connected through a pipeline.

[0052] When the air outlet pipe 425 and the air inlet pipe 221 are connected through a pipeline, and in cooperation with the air delivery pipe 30, an air circuit cycle is formed between the purification mechanism 20 and the active impurity removal mechanism. Under this air circuit cycle, through the multi-level filtration and purification of the filter assembly 21 and the cold filter assembly 42, the air purification effect at the starting section of the roller hearth furnace main body 10 and the purification effect of the surface attachments after hard carbon sintering are further improved. At the same time, the exchange of air with the outside of the roller hearth furnace main body 10 is also reduced, ensuring the stability of the purification of the purification mechanism 20 and the active impurity removal mechanism.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it.

Claims

1. A roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries, comprising a roller hearth furnace body (10), the roller hearth furnace body (10) comprising a starting section, a sintering section and a final section, characterized in that: The starting section and the ending section of the roller furnace body (10) are respectively provided with a purification mechanism (20) and an active impurity removal mechanism; The purification mechanism (20) comprises a filter assembly (21) and a circulation assembly (22), wherein the circulation assembly (22) acts on the air at the start of the roller furnace body (10), and is purified by the filter assembly (21) and then transported to the active impurity removal mechanism; The active impurity removal mechanism comprises an impurity removal component (41) and a cold filter component (42); the impurity removal component (41) comprises a discharge stage (412) and a dust collecting stage (413) disposed at the rear section of the roller furnace body (10); the discharge stage (412) comprises a plurality of horizontally and equidistantly arranged electrode plates, and the arrangement direction of the electrode plates is parallel to the material travel direction; the dust collecting stage (413) is vertically arranged at the top of the discharge stage (412) and has a width matching the width of the furnace cavity of the roller furnace body (10); the cavity of the dust collecting stage (413) is vertically connected and has a honeycomb-shaped horizontal cross section; a second gas collecting hopper (414) is disposed at the top of the dust collecting stage (413); The purification mechanism (20) and the active impurity removal mechanism are connected via an air delivery pipe (30), the output end of the air delivery pipe (30) extending to the top of the furnace chamber of the roller furnace body (10), and the air purified by the purification mechanism (20) output by the air delivery pipe (30) is blown to the outer surface of the material, and then pressurized by the dust collection stage (413) and diverted by the discharge stage (412) and evenly blown out.

2. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 1, characterized in that: The roller furnace body (10) comprises a conveying roller (11), an atmosphere pipe (13) and two partitions (12), wherein the two partitions (12) are located at two ends of the sintering section.

3. The roller hearth furnace for sintering hard carbon negative electrode of sodium ion battery according to claim 1, characterized in that: The filter assembly (21) comprises an upper filter box (211) and a lower filter box (212) arranged on the top of the roller furnace body (10); a plurality of filter screens (213) are detachably installed inside the upper filter box (211) and the lower filter box (212); the filter diameters of the plurality of filter screens (213) decrease in sequence; and a handle (214) is fixedly connected to the head end of each of the filter screens (213).

4. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 3, characterized in that: The circulation component (22) comprises an air intake pipe (221) interconnected with one side of the upper filter box (211) and a third through pipe (227) interconnected with one side of the lower filter box (212), and the air intake pipe (221) and the third through pipe (227) are close to the filter screen (213) with the largest filter diameter, and the other end of the third through pipe (227) is interconnected with a first gas collecting hopper (226), and the first gas collecting hopper (226) is fixedly connected to the starting section side wall of the roller furnace body (10); A first air pump (223) and a second air pump (229) are arranged on the top of the roller furnace body (10); an input end of the first air pump (223) is connected to the upper filter box (211) via a first through pipe (222); an input end of the second air pump (229) is connected to the lower filter box (212) via a fourth through pipe (228); and the first through pipe (222) and the fourth through pipe (228) are arranged opposite to the air inlet pipe (221) and the third through pipe (227), respectively.

5. The roller hearth furnace for sintering hard carbon negative electrode of sodium ion battery according to claim 4, characterized in that: An air supply hopper (225) is fixedly connected to the top wall of the furnace chamber at the starting section of the roller furnace body (10); an air outlet of the air supply hopper (225) is arranged obliquely downward and points to the starting section of the roller furnace body (10); The output end of the first air pump (223) is interconnected with a second through pipe (224), and the bottom end of the second through pipe (224) is connected to the top of the air delivery hopper (225).

6. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 4, characterized in that: One end of the gas delivery pipe (30) is connected to the output end of the second air pump (229), and the other end of the gas delivery pipe (30) extends to the top of the furnace chamber of the roller furnace body (10) and is in a cone shape.

7. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 1, characterized in that: The impurity removal component (41) further comprises a power supply unit (411) arranged on the top of the roller furnace body (10), and the power supply unit (411) is electrically connected to the discharge stage (412) and the dust collection stage (413); The power supply unit (411) comprises a high-voltage power supply, a transformer and a rectifier.

8. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 4, characterized in that: The impurity removal component (41) further comprises a third air pump (416) arranged on the top of the roller furnace body (10), and an input end of the third air pump (416) and a top of the second air collecting hopper (414) are connected via a fifth through pipe (415).

9. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 8, characterized in that: The cold filter assembly (42) comprises a cold filter box (422) arranged on the top of the roller furnace body (10); the output end of the third air pump (416) is interconnected with a sixth through pipe (421); the tail end of the sixth through pipe (421) penetrates from the top of the cold filter box (422) and extends to the bottom of the cold filter box (422); The outer side of the cold filter box (422) is interconnected with a liquid inlet pipe (423), a liquid outlet pipe (424), and an air outlet pipe (425).

10. The roller hearth furnace for sintering hard carbon negative electrodes for sodium ion batteries according to claim 9, characterized in that: The air outlet pipe (425) and the air inlet pipe (221) are connected via a pipeline.

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