A novel crucible for preparing sodium-ion cathode materials

Abstract

This utility model discloses a novel sagger for preparing sodium-ion cathode materials. It includes a sagger body and a sagger lid. The sagger body comprises sides, corners, and a bottom. The four sides, four corners, and a bottom enclose a sagger body with an internal hemispherical cavity structure. The inner wall of the hemispherical cavity structure is a corrugated surface. First vent holes are provided on the sides, corners, and bottom. This design ensures the overall structural strength of the sagger while allowing for a more uniform distribution of the material core within the sagger, thus ensuring more even heating of the material during sintering and faster heat transfer, improving sintering efficiency, and consequently enhancing the quality and performance of the prepared sodium-ion cathode material. It also optimizes the preparation process, reduces production costs, and meets the needs of large-scale industrial production. This sagger is widely used in the sintering of positive and negative electrode materials for lithium batteries or sodium batteries, as well as in the sintering of metallic, ceramic, and chemical materials.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a novel crucible for preparing sodium-ion cathode materials. Background Technology

[0002] With the increasing global demand for clean energy, sodium-ion batteries, due to their abundant resources and low cost, have shown broad application prospects in large-scale energy storage and other fields. As a key component of sodium-ion batteries, the manufacturing process of sodium-ion cathode materials plays a decisive role in their performance. In the preparation of sodium-ion cathode materials, the sintering process is a crucial step, and the sagger, as the key container for supporting the material during sintering, directly affects the sintering effect through its structural design.

[0003] Traditional graphite saggers typically feature smooth outer walls and regular internal shapes, resulting in limited contact area with the material and uneven heating during sintering. Due to the small contact area, traditional saggers have low heat transfer efficiency, easily leading to localized overheating or undercooling of the material, resulting in unstable material properties after sintering. Furthermore, the internal shape of traditional saggers cannot guarantee equidistant distances from the core to the sagger's perimeter and bottom, causing variations in heating conditions at different locations, further affecting the uniformity and consistency of the material and limiting the improvement of sodium-ion cathode material performance. Therefore, there is an urgent need to design a novel sagger structure to address these problems. Utility Model Content

[0004] Based on the above analysis, this utility model aims to provide a novel sagger for the preparation of sodium ion cathode materials, solving at least one of the following technical problems: traditional graphite saggers have limited contact area with the material and uneven heating of the material during sintering, resulting in unstable material properties after sintering.

[0005] The objective of this utility model is mainly achieved through the following technical solutions:

[0006] This utility model discloses a novel sagger for preparing sodium ion cathode materials, comprising a sagger body 1 and a sagger cover 2. The sagger body 1 includes a side portion 3, a corner portion 4, and a bottom portion 5. The four side portions 3, the four corner portions 4, and the bottom portion 5 enclose a sagger body 1 with an internal hemispherical cavity structure. The inner wall of the hemispherical cavity structure is a corrugated curved surface. A first vent is provided on each of the side portions 3, the corner portions 4, and the bottom portion 5.

[0007] Furthermore, the corrugations are arranged from top to bottom along the inner wall of the hemispherical cavity structure, and in the direction of the corrugation cross-section, the corrugations are at least one of sine waves, cosine waves, and sawtooth waves.

[0008] Furthermore, the corrugation height of the corrugated structure is 3-15mm, and the corrugation spacing is 8-35mm.

[0009] Furthermore, the corner portion 4 is a sector-shaped prism with a central angle of 60-90° and a radius of d~d××. ×( -1), where d is the wall thickness of the sagger, in cm.

[0010] Furthermore, the diameter of the first pore decreases along the depth direction of the first pore.

[0011] Furthermore, along the direction near the bottom 5, the diameter of the first pore decreases.

[0012] Furthermore, the first vent is not connected to the hemispherical cavity structure.

[0013] Furthermore, the inner side of the sagger cover 2 is provided with a corrugated structure that matches the interior of the hemispherical cavity structure.

[0014] Furthermore, a protrusion is provided at the upper end of the corner portion 4, and grooves matching the protrusion at the upper end of the corner portion 4 are provided at the four corners of the sagger cover 2.

[0015] Furthermore, the sagger cover 2 is provided with a second air hole with an adjustable area.

[0016] Furthermore, the sagger body 1 is symmetrically provided with handles on its outer side, and the bottom of the sagger body 1 is provided with a support structure.

[0017] Furthermore, both the sagger body 1 and the sagger lid 2 are made of graphite.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] (1) In this utility model, by designing a cubic structure around the outer wall of the sagger, with flat sides, smooth corners and a square plate shape at the bottom, the overall structural strength of the sagger can be guaranteed, while the sagger can be placed and fixed in the sintering equipment, reducing the production cost of the process, and facilitating subsequent cleaning and maintenance.

[0020] (2) Compared with the traditional cube internal shape, the four sides and four corners form a hemispherical cavity structure, which makes the material core more evenly distributed in the space inside the sagger. The distance difference between the material core and various parts inside the sagger is significantly reduced, thus ensuring that the material is heated more evenly during the sintering process. This improves the preparation quality and performance of sodium ion cathode materials, optimizes the preparation process, reduces production costs, meets the needs of large-scale industrial production, and can also adapt to different sintering process requirements and application scenarios. It can be widely used in the preparation process of various types of sodium ion cathode materials and has good versatility and practicality.

[0021] (3) In this utility model, the inner wall of the hemispherical cavity structure is a corrugated surface, which can significantly increase the contact area with the material, making the heat distribution inside the material more uniform, creating good heat transfer conditions for the uniform sintering of the material. Compared with the smooth internal structure of the traditional cube, the contact area between the hemispherical cavity structure of this invention and the material is increased by 30%-50%, which improves the heat transfer efficiency and material exchange effect, helps to promote the physical and chemical changes of the material during the sintering process, and improves the performance of the sodium ion cathode material.

[0022] (4) In this utility model, the height of the corrugated structure is 3-15mm and the corrugation spacing is 8-35mm. While ensuring that the material is in full contact, it avoids the filling and sintering effect of the material due to excessively dense or high corrugations. It ensures that the material receives consistent heat radiation and heat conduction in all directions, effectively avoids the problem of inconsistent sintering degree of the material due to uneven heating, improves the consistency and stability of sodium ion cathode material, and thus improves the overall performance of the material.

[0023] (5) In this utility model, the edges, corners and bottom are provided with first air holes, which can enable hot air flow and heat radiation to be quickly transferred to the material inside the sagger, improve sintering efficiency, reduce the difference between the bottom material and the top material, and the diameter of the first air hole decreases along the depth direction of the first air hole, and / or the diameter of the first air hole decreases along the direction close to the bottom, which can reduce the hollow ratio, ensure the strength of the sagger body itself, reduce the penetration, avoid material leakage, and make the exhaust process smoother.

[0024] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1 This is a schematic diagram of the overall structure of the sagger body of this utility model.

[0027] Figure 2 This is a schematic diagram of the overall structure of the sagger of this utility model.

[0028] Figure 3 This is a schematic diagram of the bottom of the sagger body of this utility model.

[0029] Figure 4 This is a perspective view of the overall structure of the sagger body of this utility model.

[0030] Figure 5 This is a schematic diagram of the internal structure of the sagger cover of this utility model.

[0031] Figure 6 This is a schematic diagram of the external structure of the sagger cover of this utility model.

[0032] Figure 7 This is a schematic diagram of the overall structure of the sagger body and sagger lid assembly of this utility model.

[0033] Figure label:

[0034] 1. Sagger body; 2. Sagger lid; 3. Side; 4. Corner; 5. Bottom. Detailed Implementation

[0035] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0036] This utility model provides a novel sagger for the preparation of sodium ion cathode materials. The sagger consists of a sagger body 1 and a sagger cover 2. The sagger body 1 includes a side portion 3, a corner portion 4, and a bottom portion 5. The four side portions 3, the four corner portions 4, and the bottom portion 5 enclose a sagger body 1 with an internal hemispherical cavity structure. The inner wall of the hemispherical cavity structure is a corrugated curved surface. A first air hole is provided on each of the side portions 3, the corner portions 4, and the bottom portion 5.

[0037] In this invention, the outer surface of the sagger body 1 is a smooth, near-cubic structure. This design ensures the overall structural strength of the sagger while facilitating its placement and fixation within the sintering equipment. The flat outer wall allows for close contact with the support structure inside the sintering furnace, reducing material displacement caused by sagger movement and providing a foundation for stable sintering. Furthermore, the flat outer wall is relatively simple to manufacture, reducing production costs and facilitating subsequent cleaning and maintenance, thus extending the sagger's service life.

[0038] The interior of the sagger body 1 is further divided into four sides 3, four corners 4, and a bottom 5 to form a sagger body with a hemispherical cavity structure inside and a cube-like structure on the outside. This design makes the distance from the core material to the sides and bottom of the sagger nearly equal, ensuring that the surface and interior of the material are heated evenly during sintering. This improves the quality and performance of sodium ion cathode materials, optimizes the preparation process, reduces production costs, and meets the needs of large-scale industrial production. It can be widely used in the sintering of positive and negative electrode materials for lithium batteries or sodium batteries, as well as the sintering of metal materials, ceramic materials, and chemical materials, such as LFP, NFPP, NCM, artificial graphite, hard carbon, and refractory fibers.

[0039] According to this utility model, first air holes are provided on the edge 3, corner 4 and bottom 5 so that heat can be quickly transferred to the material inside the sagger, improving sintering efficiency and reducing the difference between the material and the top material.

[0040] Furthermore, the diameter of the first pore decreases in the depth direction and / or, along the direction near the bottom 5, the diameter of the first pore decreases, which on the one hand improves the strength of the sagger body itself, and on the other hand makes the heat transfer in each direction similar, resulting in more uniform sintering of the material.

[0041] In one possible embodiment of this invention, during the sintering process of the sodium-ion cathode material, the heat transfer and mass exchange processes can be significantly improved by making the inner wall of the hemispherical cavity structure inside the crucible body 1 corrugated. On one hand, the increased contact area allows heat to be transferred more quickly and evenly from the crucible body 1 to the material, reducing localized overheating or undercooling and ensuring similar sintering conditions across all parts of the material, thus promoting the uniform formation and optimization of the crystal structure. On the other hand, the larger contact area provides more interfaces for mass exchange between the material and the crucible body 1, which is beneficial for the uniform distribution of additives and other components in the material, thereby improving the electrochemical performance of the material.

[0042] For example, in one specific embodiment of the present invention, during the sintering process of the layered oxide sodium ion cathode material, the graphite sagger 1 with the structure of the present invention can effectively avoid the decline in material performance caused by local component segregation, making the crystal structure of the material more regular, and significantly improving the charge-discharge capacity and cycle stability.

[0043] According to this utility model, considering that the production process of the sagger is smooth and there is no leakage, the first air hole is not connected to the hemispherical structure.

[0044] In this utility model, it is understood that the sagger body can be manufactured by integral molding, or it can be formed by using four sides, four corners and a bottom that meet the requirements. Considering the simplicity of the process, this utility model adopts integral molding to manufacture the sagger body.

[0045] According to this utility model, the corrugations are arranged from top to bottom along the inner wall of the hemispherical cavity structure, and the corrugations are at least one of sine wave, cosine wave, and sawtooth wave.

[0046] In this invention, the inventors discovered that different corrugated shapes have different characteristics in increasing contact area and influencing material flow. Sine and cosine wave shapes have smooth transitions, which is beneficial for the uniform distribution of materials during sintering and reduces material accumulation. Sawtooth wave shapes can provide a larger specific surface area, enhancing heat transfer and mass exchange. In the production process, different corrugated shapes or combinations of the above shapes can be set according to different needs.

[0047] According to this invention, the inventors discovered that when the corrugation height of the corrugated structure is 3-15mm and the corrugation spacing is 8-35mm, it can ensure sufficient material contact while avoiding the impact of excessively dense or high corrugations on the material's filling and sintering effect. Simultaneously, the radius of the hemispherical cavity structure is determined based on the capacity of the crucible and actual usage requirements, generally ranging from 80-400mm, to meet the needs of preparing sodium-ion cathode materials of different scales.

[0048] According to this utility model, the corner portion is a sector-shaped column, the central angle of the sector-shaped column is 60~90°, and the radius is d~d××. ×( -1)cm, where d is the wall thickness of the saggar.

[0049] In one possible embodiment of this utility model, the wall thickness of the sagger is 5-20cm.

[0050] In this invention, the central angle and radius of the fan-shaped column meet the above-mentioned range, which can alleviate stress concentration, improve crack resistance, and prevent collisions between the sagger and the outer rail during operation. Compared with right-angle columns, the fan-shaped column has a longer service life. The curvature structure of the fan-shaped column guides the heat flow to spread more evenly, avoiding the "thermal dead zone" in the right-angle area.

[0051] According to this utility model, considering that the sagger cover 2 and the sagger body 1 can fit tightly and are not easy to slip off, the inner side of the sagger cover 2 is provided with a corrugated structure that matches the hemispherical cavity structure. This can effectively reduce the contact between the material and the external environment during sintering, prevent impurities in the air from entering the sagger and contaminating the material, thus affecting the material quality. At the same time, the sagger cover can reduce heat loss to a certain extent and improve sintering efficiency.

[0052] To further ensure a tighter fit between the sagger lid 2 and the sagger body 1, a protrusion is provided at the upper end of the corner portion, and grooves matching the protrusions at the upper end of the corner portion 4 are provided at the four corners of the sagger lid 2.

[0053] According to this utility model, the sagger cover 2 is provided with a second air hole with an adjustable area.

[0054] In this invention, by adjusting the opening and closing degree of the pores, the atmosphere inside the crucible can be precisely controlled to meet the special requirements of different types of sodium ion cathode materials for sintering atmosphere (such as inert atmosphere, reducing atmosphere, etc.).

[0055] According to this utility model, considering the convenience of handling and placing the sagger, handles are symmetrically arranged on the outer side of the sagger body 1. The handles are made of the same high-purity graphite material as the sagger body and are firmly fixed to the sagger by welding or inlaying. The shape and position of the handles are ergonomically designed to ensure that operators can safely and conveniently handle the sagger.

[0056] The bottom of the sagger body 1 is provided with a support structure. The height and shape of the support structure are customized according to actual usage requirements, which can keep the sagger stable in the sintering furnace and avoid material position changes due to shaking, thus affecting the sintering effect.

[0057] According to this utility model, both the sagger body 1 and the sagger cover 2 are made of graphite. It is understood that the graphite is high-purity graphite, possessing excellent high-temperature resistance, capable of maintaining a stable structure at high temperatures of 600℃-1000℃ during the preparation of sodium-ion cathode materials, without deformation or melting, ensuring that the sagger maintains good performance even after multiple sintering uses. Its excellent chemical stability makes it less prone to chemical reactions with sodium-ion cathode materials, effectively ensuring that the purity and performance of the material are not contaminated. Simultaneously, high-purity graphite has a high thermal conductivity (100-150 W / (m²)). The kiln can quickly transfer external heat to the interior of the material, shortening the sintering time and improving production efficiency. Furthermore, the excellent processing properties of high-purity graphite allow the kiln to be machined into shapes with complex internal structures, meeting the design requirements of this invention. It is understood that the handle and support structure are also made of graphite.

[0058] Example 1

[0059] like Figure 1 As shown, the sagger body 1 includes sides 3, corners 4, and a bottom 5. The four sides 3, four corners 4, and a bottom 5 enclose a sagger body 1 with an internal hemispherical cavity structure. The inner wall of the hemispherical cavity structure is a corrugated surface. The exterior of the sagger body is a near-cubic structure with flat sides, smooth corner transitions, and a square-shaped bottom. The corrugations are arranged from top to bottom along the inner wall of the hemispherical cavity structure. The corrugations are sinusoidal waves with a height of 5 mm and a spacing of 15 mm. The radius of the hemispherical structure is 150 mm. Each side 3, corner 4, and bottom 5 has a first air hole. The diameter of the first air hole decreases along its depth direction. The first air hole is not connected to the hemispherical structure.

[0060] This graphite crucible was used to prepare layered oxide sodium-ion cathode materials. During the sintering process, the core material was placed in a suitable position inside the crucible. Because the interior is a hemispherical cavity structure formed by the four sides and four corners, and the inner wall of this hemispherical cavity structure is corrugated, the contact area between the material and the crucible is significantly increased, resulting in uniform heat transfer. Simultaneously, the hemispherical structure ensures consistent heating across all parts of the material, allowing for sufficient transformation and optimization of the crystal structure. After sintering, the prepared layered oxide sodium-ion cathode material exhibits a uniform crystal structure and consistent grain size. In charge-discharge tests, the initial discharge capacity was 18% higher than that of materials prepared using traditional crucibles, and the capacity retention rate after 100 cycles reached 93%.

[0061] Example 2

[0062] The sagger body 1 includes sides 3, corners 4, and a bottom 5. The four sides 3, four corners 4, and a bottom 5 enclose a sagger body 1 with an internal hemispherical cavity structure. The inner wall of the hemispherical cavity structure is a corrugated surface. The exterior of the sagger body is a near-cubic structure with flat sides, smooth corner transitions, and a square plate-shaped bottom. The corrugations are a combination of sawtooth and cosine waves, with a corrugation height of 8 mm and a corrugation spacing of 20 mm. The radius of the hemispherical structure is 250 mm. It is equipped with a corresponding sagger cover 2, handle, and support structure.

[0063] This sagger was applied to the preparation of Prussian blue sodium-ion cathode materials. During sintering, the material was in full contact with the internal corrugated structure, achieving efficient heat transfer and mass exchange. The hollow structure ensured uniform heating of the material and effectively avoided local component segregation. Simultaneously, by adjusting the pores on the sagger lid, the inert atmosphere inside the sagger was controlled, meeting the sintering requirements of Prussian blue materials. The resulting Prussian blue sodium-ion cathode material exhibited a regular crystal structure, and its charge-discharge capacity and cycle stability were significantly superior to materials prepared using traditional saggers, retaining a capacity retention of up to 88% after 200 cycles.

[0064] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A new type of saggar for sodium-ion cathode material preparation, characterized in that, Includes a sagger body (1) and a sagger lid (2). The sagger body (1) includes a side (3), a corner (4) and a bottom (5). The four sides (3), four corners (4) and a bottom (5) enclose the sagger body (1) with a hemispherical cavity structure inside. The inner wall of the hemispherical cavity structure is a corrugated surface. The edge (3), corner (4) and bottom (5) are each provided with a first air hole.

2. The sagger of claim 1, wherein, The corrugations are arranged from top to bottom along the inner wall of the hemispherical cavity structure, and in the cross-sectional direction of the corrugations, the corrugations are at least one of sine waves, cosine waves, and sawtooth waves.

3. The sagger of claim 1, wherein, The corrugated structure has a corrugation height of 3-15mm and a corrugation spacing of 8-35mm.

4. The sagger of claim 1, wherein, The corner (4) is a sector column, the central angle of the sector column is 60-90°, and the radius is d~d× ×( -1), wherein d is the thickness of the saggar wall, in cm.

5. The sagger of claim 1, wherein, Along the depth direction of the first pore, the diameter of the first pore decreases. And / or, along the direction near the bottom (5), the diameter of the first pore decreases; And / or, the first pore is not connected to the hemispherical cavity structure.

6. The sagger of claim 1, wherein, The inner side of the sagger cover (2) is provided with a corrugated structure that matches the interior of the hemispherical cavity structure.

7. The sagger of claim 1 wherein, The upper end of the corner (4) is provided with a protrusion, and the four corners of the sagger cover (2) are provided with grooves that match the protrusion at the upper end of the corner (4).

8. The sagger of claim 1, wherein, The sagger cover (2) is provided with a second air hole with an adjustable area.

9. The sagger of claim 1, wherein, The sagger body (1) has handles symmetrically arranged on the outside, and a support structure is provided at the bottom of the sagger body (1).

10. The sagger according to any one of claims 1-9, wherein, The sagger body (1) and sagger lid (2) are both made of graphite.

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