Methods for manufacturing metal crucibles and crucible lids

Abstract

This invention discloses a method for manufacturing a metal crucible and a crucible lid, belonging to the field of lithium-ion battery anode material processing technology. The method for manufacturing the metal crucible includes: obtaining a crucible metal body and a bottom using a stainless steel plate with a heat resistance greater than 950℃; welding the crucible metal body to the bottom to obtain a crucible metal liner; and covering the entire surface of the crucible metal liner with a crucible isolation layer to obtain the crucible body, wherein the crucible isolation layer protects the crucible metal liner. This invention uses a metal crucible with an isolation layer covering its entire surface to load semi-finished lithium-ion battery anode material, replacing the silicon carbide crucible. For the same outer diameter and height, the manufacturing method of the metal crucible is simple, and the manufacturing cost is less than 1 / 3 of that of a silicon carbide crucible. Since the service life of the metal crucible is several times that of the silicon carbide crucible, the cost per use is extremely low, while ensuring the product quality of the lithium-ion battery anode material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery anode material processing technology, and in particular to a method for manufacturing a metal crucible and a method for manufacturing a crucible lid. Background Technology

[0002] In related technologies, when producing artificial graphite anode materials for lithium-ion power batteries, the semi-finished product after granulation in the reaction vessel is loaded into a silicon carbide crucible and calcined at high temperature in a tunnel kiln to remove the volatiles contained in the material, increase the specific gravity of the material, thereby increasing the furnace loading during graphitization and reducing safety hazards.

[0003] However, the production process of silicon carbide crucibles is complex, the manufacturing cycle of large-size crucibles is long, and the yield of large-size silicon carbide crucibles is very low, resulting in high production costs. Summary of the Invention

[0004] The main objective of this invention is to provide a method for manufacturing a metal crucible and a crucible lid, aiming to solve the technical problems of complex production processes for silicon carbide crucibles, long processing and manufacturing cycles for large-size crucibles, and very low yield rates in the production of large-size silicon carbide crucibles in the prior art.

[0005] To achieve the above objectives, according to a first aspect of the present disclosure, the present invention provides a method for manufacturing a metal crucible, the method comprising:

[0006] The crucible metal body and bottom are obtained using a stainless steel plate with a heat resistance temperature greater than 950℃.

[0007] The crucible metal body is welded to the bottom of the cylinder to obtain a crucible metal liner;

[0008] A crucible isolation layer is applied to the entire surface of the crucible metal liner to obtain a metal crucible body. The crucible isolation layer is used to prevent the crucible metal liner from oxidizing or corroding under high temperature open flame and to avoid direct contact between the crucible metal liner and the lithium-ion battery negative electrode material.

[0009] Optionally, the step of covering the entire surface of the crucible metal liner with a crucible isolation layer includes:

[0010] Chemical vapor deposition of silicon carbide is applied to the outer surface of the crucible metal liner to form a crucible chemical vapor deposition silicon carbide film;

[0011] A carbon coating or a graphite coating is applied to the inner surface of the crucible metal liner to form a crucible carbon coating or a crucible graphite coating, thereby obtaining the crucible isolation layer.

[0012] Optionally, the step of covering the entire surface of the crucible metal liner with a crucible isolation layer includes:

[0013] Chemical vapor deposition of silicon carbide is applied to the entire surface of the crucible metal liner to form a crucible chemical vapor deposition silicon carbide film, thereby obtaining the crucible isolation layer.

[0014] Optionally, the step of covering the entire surface of the crucible metal liner with a crucible isolation layer includes:

[0015] After covering the entire surface of the crucible metal liner with chemical vapor deposition of silicon carbide to form a crucible chemical vapor deposition silicon carbide film, a carbon coating or a graphite coating is then applied to the inner surface of the crucible metal liner to form a crucible carbon coating or a crucible graphite coating.

[0016] The crucible carbon coating or crucible graphite coating covers the entire surface of the crucible chemical vapor deposition silicon carbide film located inside the crucible metal liner to obtain the crucible isolation layer.

[0017] Optionally, the thickness of the stainless steel plate is 2mm to 8mm.

[0018] According to a second aspect of the present disclosure, the present invention also provides a method for manufacturing a crucible lid, the method comprising:

[0019] A stainless steel plate with a heat resistance temperature greater than 950℃ is cut into a cover plate to obtain the cover body.

[0020] A stainless steel sidewall of the same material is welded perpendicularly around the periphery of the cover plate to form a cover metal liner that is closed on one side.

[0021] An opening is formed on the closed side of the crucible lid semi-finished product, and a stainless steel breathable grid with a heat resistance temperature greater than 950°C is horizontally welded to the inner wall of the metal liner to obtain the crucible lid semi-finished product.

[0022] A cover isolation layer is applied to the entire surface of the cover metal liner to obtain the cover body, wherein the cover isolation layer is used to prevent the cover metal liner from oxidizing or corroding under high temperature open flame.

[0023] Optionally, the step of covering the entire surface of the cover metal liner with a cover isolation layer includes:

[0024] Chemical vapor deposition of silicon carbide is applied to the outer surface of the cover metal liner to form a cover chemical vapor deposition silicon carbide film;

[0025] A carbon coating or a graphite coating is applied to the inner surface of the metal liner of the cover to form a cover carbon coating or a cover graphite coating, thereby obtaining the cover isolation layer.

[0026] Optionally, the step of covering the entire surface of the cover metal liner with a cover isolation layer includes:

[0027] Silicon carbide is deposited by chemical vapor deposition onto the entire surface of the cover metal liner to form a cover chemical vapor deposition silicon carbide film, thereby obtaining the cover isolation layer.

[0028] Optionally, the step of covering the entire surface of the cover metal liner with a cover isolation layer includes:

[0029] After covering the entire surface of the cover metal liner with chemical vapor deposition of silicon carbide to form a crucible chemical vapor deposition silicon carbide film, a carbon coating or a graphite coating is then applied to the inner surface of the cover metal liner to form a cover carbon coating or a cover graphite coating.

[0030] The cover carbon coating or cover graphite coating covers the entire surface of the cover chemical vapor deposition silicon carbide film located inside the cover metal liner to obtain the cover isolation layer.

[0031] Optionally, the thickness of the stainless steel plate is 2mm to 8mm.

[0032] The technical solution of this invention uses a metal crucible with an insulating layer covering the entire surface to load semi-finished lithium-ion battery anode material, replacing the silicon carbide crucible. Under the same outer diameter and height, the manufacturing method of the metal crucible is simple, and the manufacturing cost is less than 1 / 3 of that of the silicon carbide crucible. Since the service life of the metal crucible is several times that of the silicon carbide crucible, the cost per use is extremely low. After multiple uses, there will be no material peeling off. In addition, the insulating layer can also prevent the crucible metal liner from oxidizing or being corroded by volatile gases under high temperature open flame, and prevent the crucible metal liner from directly contacting the semi-finished lithium-ion battery anode material, thus preventing the introduction of trace metal impurities and ensuring the product quality of the lithium-ion battery anode material. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the metal crucible of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the crucible lid of the present invention;

[0036] Figure 3This is a front view of the crucible assembly of the present invention.

[0037] Figure 4 This is a side view of the crucible assembly of the present invention.

[0038] Figure 5 This is a cross-sectional view of an embodiment of the metal crucible of the present invention;

[0039] Figure 6 This is a schematic diagram showing the usage state of the quick-locking bolt of the present invention;

[0040] Figure 7 This is a cross-sectional structural schematic diagram of an embodiment of the crucible lid of the present invention;

[0041] Figure 8 This is a cross-sectional view of another embodiment of the metal crucible of the present invention;

[0042] Figure 9 This is a cross-sectional view of another embodiment of the crucible lid of the present invention;

[0043] Figure 10 This is a schematic flowchart of the method for manufacturing the metal crucible of the present invention;

[0044] Figure 11 This is a schematic flowchart of the method for manufacturing the crucible lid of the present invention.

[0045] Explanation of icon numbers:

[0046]

[0047] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0052] In related technologies, artificial graphite anode materials for lithium-ion power batteries commonly use petroleum coke or needle coke as raw materials. The volatile matter content of petroleum coke and needle coke is typically as high as 7%–13%. After mechanical grinding, shaping, and grading, the volatile matter content remains almost unchanged. Even after granulation in a high-temperature reactor at 600℃–700℃, the volatile matter content can only be reduced to between 4% and 8%, making complete removal difficult. Directly loading the pulverized or granulated coke semi-finished product into a graphitization furnace for graphitization at near 3000℃ causes the volatile matter to overflow and burn at the top of the furnace, potentially leading to material ejection and posing a significant safety hazard. Furthermore, the high-temperature graphitization process of lithium-ion battery anode materials consumes a large amount of electrical energy, and the loading and unloading operations are complex and the production cycle is long. If the volatile matter content of the semi-finished anode material before loading is high, the yield of the graphitization process will be low, significantly increasing production costs.

[0053] To address the aforementioned issues, a tunnel kiln is used to perform high-temperature calcination on the semi-finished anode material before graphitization. This reduces the volatile matter content to 1% or less, thereby eliminating the safety hazards caused by high volatile matter content during graphitization and significantly lowering production costs. This type of tunnel kiln typically uses natural gas as fuel and a silicon carbide crucible as a container. The semi-finished anode material to be calcined is loaded into the crucible, covered, placed on a track kiln car, and then sent into the tunnel kiln for open-flame calcination. The calcination temperature typically reaches over 900℃.

[0054] However, silicon carbide crucibles have the following problems:

[0055] 1. The production process is complex, and the manufacturing cycle for large-sized crucibles is long, usually more than 2 months;

[0056] 2. The yield rate of large-size silicon carbide crucibles is very low and the manufacturing cost is very high. For example, the manufacturing cost of a set of silicon carbide crucibles with a diameter of Ф450mm (outer diameter), Ф400mm (inner diameter), and a height of 1200mm can be as high as several thousand yuan.

[0057] 3. Silicon carbide crucibles have a limited lifespan, typically 30-50 uses, resulting in high costs per use.

[0058] 4. After repeated use, silicon carbide crucibles may experience material peeling off, especially near the end of their service life. The peeling off material mixed with the negative electrode material will become a harmful impurity, which is difficult to completely remove during the high-temperature graphitization stage.

[0059] 5. To improve mechanical strength, large-size silicon carbide crucibles typically have a wall thickness of over 20mm, resulting in a relatively small effective volume and reduced material loading.

[0060] Therefore, this invention provides a method for manufacturing a metal crucible and a crucible lid. A metal crucible with an insulating layer covering its entire surface is used to load semi-finished lithium-ion battery negative electrode material, replacing a silicon carbide crucible. For the same outer diameter and height, the metal crucible is simpler to manufacture, and its manufacturing cost is less than one-third that of a silicon carbide crucible. Furthermore, since the service life of a metal crucible is several times that of a silicon carbide crucible, the cost per use is extremely low. After multiple uses, there is no material peeling off. The insulating layer also prevents the crucible's metal lining from oxidizing or corroding under high-temperature open flame and avoids direct contact between the crucible's metal lining and the semi-finished lithium-ion battery negative electrode material, preventing the introduction of trace metal impurities and ensuring the product quality of the lithium-ion battery negative electrode material.

[0061] The concept of the present invention will be further explained below with reference to some specific embodiments.

[0062] This invention proposes a method for manufacturing a metal crucible.

[0063] Reference Figure 1 , Figure 5 and Figure 10 , Figure 1 This is a schematic diagram of the structure of the metal crucible of the present invention; Figure 5 This is a cross-sectional view of an embodiment of the metal crucible of the present invention; Figure 10 This is a schematic flowchart illustrating the manufacturing method of the metal crucible of the present invention.

[0064] In one embodiment of the present invention, such as Figure 1 , Figure 5 and Figure 10 As shown, the method for manufacturing a metal crucible includes:

[0065] S100: The crucible metal body and bottom are obtained using a stainless steel plate with a heat resistance temperature greater than 950℃.

[0066] S200: Weld the metal crucible body to the bottom of the cylinder to obtain the crucible metal liner 101;

[0067] S300: Cover the entire surface of the crucible metal liner 101 with a crucible isolation layer 102 to obtain a crucible body 100. The crucible isolation layer 102 is used to prevent the crucible metal liner 101 from oxidizing or corroding under high temperature open flame and to avoid direct contact between the crucible metal liner 101 and the lithium-ion battery negative electrode material.

[0068] For ease of understanding, a specific implementation method for making a metal crucible is shown here:

[0069] B100: A stainless steel plate with a heat resistance temperature greater than 950℃ is rolled into a cylindrical shape using a plate rolling machine, and the rolled stainless steel plate is seamlessly welded to obtain the crucible metal body.

[0070] B200: Use a cutting machine to cut another stainless steel plate into a disc shape to obtain a cylinder bottom that fits the metal body of the crucible;

[0071] B300: The bottom of the crucible metal liner 101 is formed by seamless welding at one end of the crucible metal body.

[0072] B400: The crucible isolation layer 102 is covered on the entire surface of the crucible metal liner 101, that is, the crucible isolation layer 102 is covered on both the inner and outer surfaces of the crucible metal liner 101 to obtain the crucible body 100.

[0073] It should be noted that the crucible isolation layer 102 in this embodiment can be formed by chemical vapor deposition of silicon carbide.

[0074] This invention uses a metal crucible with a crucible isolation layer 102 covering its entire surface to load semi-finished lithium-ion battery negative electrode materials, replacing the silicon carbide crucible. Under the same outer diameter and height, the manufacturing method of the metal crucible is simple, and the manufacturing cost is less than 1 / 3 of that of the silicon carbide crucible. Furthermore, since the service life of the metal crucible is several times that of the silicon carbide crucible, the cost per use is extremely low. In addition, the crucible isolation layer 102 on the surface of the crucible can prevent the metal liner from oxidizing or being corroded by volatile gases under high temperature open flame, and can also prevent the crucible metal liner 101 from directly contacting the semi-finished lithium-ion battery negative electrode materials, thus preventing the introduction of trace metal impurities.

[0075] Furthermore, there is no material peeling after multiple uses, ensuring the product quality of lithium-ion battery anode materials.

[0076] As an alternative to this example, the step of covering the entire surface of the crucible metal liner 101 with the crucible isolation layer 102 includes:

[0077] B500: Chemical vapor deposition of silicon carbide is applied to the outer surface of the crucible metal liner 101 to form a crucible chemical vapor deposition silicon carbide film 500;

[0078] B510: A carbon coating or graphite coating is applied to the inner surface of the crucible metal liner 101 to form a crucible carbon coating or crucible graphite coating 400, thereby obtaining a crucible isolation layer 102.

[0079] For ease of understanding, a specific embodiment is shown here:

[0080] The specific implementation process of covering the inner surface of the crucible metal liner 101 with a crucible carbon coating or crucible graphite coating 400 is as follows: a carbon or graphite emulsion is sprayed or brushed onto the inner surface of the crucible metal liner 101. After the carbon or graphite emulsion solidifies, a crucible carbon coating or crucible graphite coating 400 is formed, completely covering the inner surface of the crucible metal liner 101. The preparation cost of the carbon coating or graphite coating is low, and the implementation difficulty is also low.

[0081] Understandably, the crucible isolation layer 102 prevents the crucible metal liner 101 from oxidizing or corroding under high-temperature open flame, and also prevents the crucible metal liner 101 from directly contacting the lithium-ion battery negative electrode material semi-finished product, thus avoiding the introduction of trace metal impurities. Chemical vapor deposition of silicon carbide, also known as CVD silicon carbide, uses a vapor deposition apparatus to form a crucible chemical vapor deposition silicon carbide film 500 on the surface (outer surface and / or inner surface) of the crucible metal liner 101.

[0082] Specifically, CVD refers to a method for synthesizing coatings or nanomaterials by reacting chemical gases or vapors on the surface of a substrate. It is understood that those skilled in the art know how to perform CVD, and will not be elaborated upon here.

[0083] As an alternative to this example, the step of covering the entire surface of the crucible metal liner 101 with a crucible isolation layer includes:

[0084] B600: Chemical vapor deposition of silicon carbide covers the entire surface of the crucible metal liner 101 to form a crucible chemical vapor deposition silicon carbide film 500, thereby obtaining the crucible isolation layer 102.

[0085] Reference Figure 8 , Figure 8 This is a cross-sectional view of another embodiment of the metal crucible of the present invention.

[0086] As another option in this example, such as Figure 8 As shown, the step of covering the entire surface of the crucible metal liner 101 with the crucible isolation layer 102 includes:

[0087] B700: After covering the entire surface of the crucible metal liner 101 with chemical vapor deposition silicon carbide to form a crucible chemical vapor deposition silicon carbide film 500, a carbon coating or a graphite coating is then applied to the inner surface of the crucible metal liner 101 to form a crucible carbon coating or a crucible graphite coating 400.

[0088] The crucible carbon coating or crucible graphite coating 400 covers the entire surface of the crucible chemical vapor deposition silicon carbide film 500 located inside the crucible metal liner 101 to obtain the crucible isolation layer 102.

[0089] For ease of understanding, a specific embodiment is shown here:

[0090] First, silicon carbide is deposited by chemical vapor deposition onto the inner surface of the crucible metal liner 101 to form a crucible chemical vapor deposition silicon carbide film 500. Then, carbon or graphite emulsion is sprayed or brushed onto the surface of the silicon carbide film. After baking at a high temperature of 150℃~200℃, a composite coating of crucible carbon coating or crucible graphite coating 400 and chemical vapor deposition silicon carbide film 500 is formed on the inner surface of the crucible.

[0091] During the high-temperature calcination of the metal crucible containing the semi-finished lithium-ion battery negative electrode material in a tunnel kiln, the silicon carbide film 500 deposited by chemical vapor deposition on the outer surface of the crucible will not peel off. This prevents the crucible metal liner 101 from oxidizing under high-temperature open flame or being corroded by volatile gases emitted from the material. The carbon coating or graphite coating 400 on the inner surface of the crucible prevents the crucible metal liner 101 or the silicon carbide film 500 from directly contacting the negative electrode material and introducing impurities. The amount of carbon or graphite coating 400 is very small and has the same composition as the negative electrode material. Even if it peels off after multiple uses of the crucible, it will not contaminate the negative electrode material, ensuring product quality. It is understood that the crucible isolation layer 102 does not contain any elemental metal components. Isolation layers with other components can also be used to form the crucible isolation layer 102 of this invention. This embodiment shows a preferred implementation.

[0092] In this embodiment, the thickness of the stainless steel plate is 2mm to 8mm.

[0093] When the thickness of the crucible metal liner 101 is less than 2 mm, the overall structure of the crucible metal liner 101 will deform during the high-temperature calcination of the semi-finished lithium-ion battery negative electrode material, affecting the normal use of the metal crucible.

[0094] When the thickness of the crucible metal liner 101 is greater than 8 mm, the weight of the metal crucible increases significantly, increasing the burden on the transport mechanism and increasing the production cost of the lithium-ion battery anode material semi-finished product. Furthermore, the heat transfer rate is slow during high-temperature calcination, reducing the production efficiency of the lithium-ion battery anode material semi-finished product. In addition, it will cause the overall strength of the metal crucible to be excessive, which is not conducive to controlling production costs. Therefore, in order to ensure the mechanical strength of the crucible metal liner 101 while ensuring the effective volume of the metal crucible, and to increase the filling amount of lithium-ion battery anode material semi-finished product compared with a silicon carbide crucible of the same size, in a preferred embodiment, the thickness of the crucible metal liner 101 is limited to 2 mm to 8 mm.

[0095] In this embodiment, the stainless steel material used for the crucible metal liner 101 is any one of 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S), or 253MA (S30815).

[0096] To ensure that the crucible metal liner 101 has high high-temperature strength and oxidation resistance, in a preferred embodiment, the stainless steel material used for the crucible metal liner 101 is any one of 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S) or 253MA (S30815).

[0097] Specifically, in this embodiment and other embodiments:

[0098] 1Cr25Ni20Si2(314) has high high-temperature strength and oxidation resistance, is sensitive to sulfur-containing atmosphere, and has a tendency to embrittle with precipitated phases at 600-800℃. It is suitable for making various furnace components that bear stress.

[0099] 1Cr20Ni14Si2 has high high-temperature strength and oxidation resistance, but is sensitive to sulfur-containing atmospheres and tends to become embrittled at 600℃-800℃. It is suitable for making furnace components. Tensile strength: 590MPa, hardness: ≤187.

[0100] 0Cr23Ni13 (309S) is a variant of 309 stainless steel with a lower carbon content, used in applications requiring welding.

[0101] 253MA (S30815) is a stainless steel that combines excellent performance at high temperatures with ease of manufacture. It is oxidation resistant up to 1150°C and offers superior serviceability compared to grade 310 in carbon, nitrogen, and sulfur atmospheres. 253MA contains a relatively low nickel content, which gives it some advantages in reducing sulfide atmospheres compared to high-nickel alloys and 310 steel. High silicon, nitrogen, and cerium content contributes to good oxide stability, high-temperature strength, and excellent resistance to σ-phase precipitation.

[0102] It is understood that those skilled in the art know how to implement 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S) or 253MA (S30815), and will not be described in detail here.

[0103] The present invention also proposes a method for manufacturing a crucible lid.

[0104] Reference Figure 2 , Figure 7 and Figure 11 , Figure 2 This is a schematic diagram of the structure of the crucible lid of the present invention; Figure 7 This is a cross-sectional structural schematic diagram of an embodiment of the crucible lid of the present invention; Figure 11 This is a schematic flowchart of the method for manufacturing the crucible lid of the present invention.

[0105] In one embodiment of the present invention, such as Figure 2 , Figure 7 and Figure 11 As shown, the method for manufacturing the crucible lid includes:

[0106] A100: Cut a stainless steel plate with a heat resistance temperature greater than 950℃ into a cover plate to obtain a cover body.

[0107] A200: Weld a stainless steel sidewall of the same material perpendicularly around the perimeter of the cover plate to form a semi-finished cover that is closed on one side.

[0108] A:300: An opening 210 is formed on one side of the closed crucible lid semi-finished product, and a stainless steel breathable grid 220 with a heat resistance temperature greater than 950℃ is horizontally welded to the inner wall of the crucible lid semi-finished product to obtain a crucible lid metal liner 201.

[0109] A400: Cover the entire surface of the cover metal liner with a cover isolation layer 202 to obtain a cover body 200, wherein the cover isolation layer 202 is used to prevent the cover metal liner 201 from oxidizing or corroding under high temperature open flame.

[0110] For ease of understanding, a specific implementation method for manufacturing the crucible lid is shown here:

[0111] P100: Cut a stainless steel plate with a heat resistance temperature greater than 950℃ into a cover plate, then weld a stainless steel sidewall of the same material around the outer edge of the ring vertically to form a closed structure on one side, and then weld a stainless steel venting grid 220 with a heat resistance temperature greater than 950℃ horizontally around the inner circle of the ring. The venting grid 220 is used to prevent foreign objects or debris from entering the crucible, thus obtaining a cover metal liner 201, wherein the inner diameter of the cover metal liner 201 is more than 10mm smaller than the outer diameter.

[0112] P200: Cover the entire surface of the cover metal liner 201 with the cover isolation layer 202 to obtain the cover body 200.

[0113] This invention uses a crucible lid made of stainless steel plate, replacing the silicon carbide crucible lid. For the same dimensions, the stainless steel lid is simpler to manufacture and has a lower production cost than the silicon carbide lid. Since the stainless steel lid has a lifespan several times longer than the silicon carbide lid, the cost per use is extremely low. After multiple uses, there is no material peeling off. Furthermore, the entire surface of the metal liner 201 is covered with a lid isolation layer 202, meaning both the inner and outer surfaces of the metal liner 201 are covered with this layer. This prevents the metal liner 201 from oxidizing or being corroded by volatile gases under high-temperature open flame. Even if the lid isolation layer 202 peels off after multiple uses, the amount is very small due to the thinness of the layer and will not significantly affect the quality of the lithium-ion battery negative electrode material.

[0114] A400: An opening 210 is formed on the closed side of the cover metal liner 201, that is, an opening 210 is formed on the cover plate.

[0115] In this embodiment, the crucible lid includes a ventilated grid 220, which is disposed at the opening 210 and matches the opening 210.

[0116] Understandably, the shape of opening 210 can be any polygon or circle.

[0117] When calcining semi-finished lithium-ion battery anode material at high temperatures, the semi-finished anode material is first placed into a metal crucible, then the crucible lid is placed over the opening 210 of the crucible, and the crucible is loaded into a kiln car and sent into the kiln. When the kiln car reaches the high-temperature zone of the kiln, the semi-finished anode material is heated and releases most of its volatiles. The opening 210 of the crucible lid and the ventilation grille 220 facilitate the discharge of volatiles from the metal crucible into the kiln.

[0118] In addition to facilitating the discharge of volatiles from the metal crucible containing the semi-finished lithium-ion battery negative electrode material, the ventilated grille 220 also helps to quickly dissipate heat from the crucible during the cooling stage, thus accelerating the cooling rate.

[0119] As an alternative to this embodiment, the step of covering the entire surface of the cover metal liner 201 with the cover isolation layer 202 includes:

[0120] C100: Chemical vapor deposition (CVD) silicon carbide is applied to the outer surface of the cover metal liner 201 to form a cover chemical vapor deposition silicon carbide film 600.

[0121] C200: A carbon coating or graphite coating 400 is applied to the inner surface of the cover metal liner 201 to form a cover carbon coating or cover graphite coating 700, thereby obtaining a cover isolation layer 202.

[0122] The crucible chemical vapor deposition silicon carbide film 600 on the outer surface of the metal liner 201 can prevent the metal liner 201 from oxidizing or being corroded by volatile gases under high temperature open flame, thus ensuring the service life of the crucible lid; the cap carbon coating or cap graphite coating 700 on the inner surface of the metal liner 201 can prevent the metal liner 201 from directly contacting the lithium-ion battery negative electrode material semi-finished product and introducing trace metal impurities.

[0123] Specifically, CVD refers to a method for synthesizing coatings or nanomaterials by reacting chemical gases or vapors on the surface of a substrate. It is understood that those skilled in the art know how to perform CVD, and will not be elaborated upon here.

[0124] As an alternative to this example, the step of covering the entire surface of the cover metal liner 201 with the cover isolation layer 202 includes:

[0125] C:300: Chemical vapor deposition of silicon carbide is applied to the entire surface of the cover metal liner 201 to form a cover chemical vapor deposition silicon carbide film 600, thereby obtaining the cover isolation layer 202.

[0126] The cover isolation layer 202 is chemical vapor deposition silicon carbide, i.e., CVD silicon carbide. A cover chemical vapor deposition silicon carbide film 600 is formed on all surfaces (inner and outer surfaces) of the cover metal liner 201 using a vapor deposition device. This prevents the cover metal liner 201 from oxidizing or corroding under high temperature open flame and prevents the cover metal liner 201 from coming into contact with the lithium-ion battery negative electrode material semi-finished product, thus avoiding the introduction of trace metal impurities.

[0127] Reference Figure 9 , Figure 9 This is a cross-sectional structural schematic diagram of another embodiment of the crucible lid of the present invention.

[0128] As another option in this example, such as Figure 9 As shown, the step of covering the entire surface of the cover metal liner 201 with the cover isolation layer 202 includes:

[0129] C400: After covering the entire surface of the cover metal liner 201 with chemical vapor deposition silicon carbide to form a cover chemical vapor deposition silicon carbide film 600, a carbon coating or graphite coating is covered on the inner surface of the cover metal liner 201 to form a cover carbon coating or cover graphite coating 700.

[0130] In this process, a carbon coating or graphite coating 700 covers the entire surface of the cover chemical vapor deposition silicon carbide film 600 located inside the cover metal liner 201 to obtain the cover isolation layer 202.

[0131] During the high-temperature calcination of the metal crucible containing the semi-finished lithium-ion battery negative electrode material in a tunnel kiln, the cover metal liner 201's outer surface covered with a cover chemical vapor deposition silicon carbide film 600 will not peel off. This prevents the cover metal liner 201 from oxidizing under high-temperature open flame or being corroded by volatile gases emitted from the material. The cover carbon coating or cover graphite coating 700 on the inner surface prevents the cover metal liner 201 or the cover chemical vapor deposition silicon carbide film 600 from directly contacting the negative electrode material and introducing impurities. The amount of cover carbon coating or cover graphite coating 700 is very small and has the same composition as the negative electrode material. Even if it peels off after multiple uses of the crucible, it will not contaminate the negative electrode material, ensuring product quality.

[0132] It is understood that the cover isolation layer 202 does not contain any metallic elemental components. Isolation layers with other components can also be used to form the cover isolation layer 202 of the present invention. The embodiment shown here is a preferred implementation.

[0133] In this embodiment, the thickness of the stainless steel plate is 2mm to 8mm.

[0134] When the thickness of the metal liner 201 is less than 2mm, the overall structure of the metal liner 201 will deform during the high-temperature calcination of the semi-finished lithium-ion battery negative electrode material, affecting the normal use of the crucible cover.

[0135] When the thickness of the metal liner 201 of the lid is greater than 8mm, the weight of the crucible lid increases significantly, increasing the burden on the transport mechanism for transporting the crucible lid and increasing the production cost of the semi-finished lithium-ion battery anode material. Furthermore, the heat transfer rate is slow during the high-temperature calcination process, reducing the production efficiency of the semi-finished lithium-ion battery anode material. In addition, it will make the overall strength of the crucible lid excessive, which is not conducive to controlling production costs. Therefore, in a preferred embodiment, the thickness of the metal liner 201 of the lid is limited to 2mm to 8mm.

[0136] In this embodiment, the stainless steel material used for the cover metal liner 201 is any one of 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S) or 253MA (S30815).

[0137] To ensure that the cover metal liner 201 has high high-temperature strength and oxidation resistance, in a preferred embodiment, the cover metal liner 201 is made of stainless steel material of any one of 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S) or 253MA (S30815).

[0138] It is understood that those skilled in the art know how to implement 1Cr25Ni20Si2 (314), 1Cr20Ni14Si2, 0Cr23Ni13 (309S) or 253MA (S30815), and will not be described in detail here.

[0139] The present invention also proposes a crucible assembly.

[0140] Reference Figure 3 , Figure 4 and Figure 6 , Figure 3 This is a front view of the crucible assembly of the present invention. Figure 4 This is a side view of the crucible assembly of the present invention. Figure 6 This is a schematic diagram showing the usage state of the quick-locking bolt 330 of the present invention.

[0141] In one embodiment of the present invention, such as Figure 3 , Figure 4 and Figure 6As shown, the crucible assembly includes:

[0142] The aforementioned metal crucible; and

[0143] The aforementioned crucible lid covers the metal crucible;

[0144] In one embodiment, the crucible assembly further includes:

[0145] At least two limiting members 320 are evenly distributed on the outer peripheral wall of the metal crucible, and the limiting members 320 are connected to the outer peripheral wall of the metal crucible by welding.

[0146] At least two bases 310 are evenly distributed on the outer peripheral wall of the crucible lid. The bases 310 and the limiting members 320 are respectively arranged one-to-one. There is a horizontal crossbar 333 on the base 310. The horizontal crossbar 333 passes through the fixing ring 332 at the upper end of the quick-lock bolt 330, so that the quick-lock bolt 330 can be fixed on the crucible lid.

[0147] At least two quick-lock bolts 330 are provided, each corresponding to a limiting member 320. The upper fixing ring 332 is fixed to the outer peripheral wall of the crucible lid via a horizontal crossbar 333 of the base 310. The lower end is tightened by a quick-lock nut 331 in conjunction with the limiting member 320, thereby allowing the crucible lid to fit over the crucible body 100.

[0148] At least two hooks 340 are evenly distributed on the outer peripheral wall of the metal crucible;

[0149] The limiting member 320 and the hook 340 are spaced apart from each other in the circumferential direction of the metal crucible.

[0150] During the high-temperature calcination of the semi-finished lithium-ion battery negative electrode material, at least two limiting members 320 are evenly distributed on and connected to the outer peripheral wall of the metal crucible to facilitate rapid connection between the metal crucible and the crucible lid. A space is formed between the limiting members 320 and the outer peripheral wall of the metal crucible for the quick-locking bolt 330 to be positioned and the quick-locking nut 331 to rotate. At least two bases 310 are evenly distributed on the outer peripheral wall of the crucible lid, with each base 310 corresponding to one of the limiting members 320. Each base 310 has a horizontal crossbar 333 that passes through the ring at the upper end of the quick-locking bolt 330, fixing the quick-locking bolt 330 to the outer peripheral wall of the crucible lid. The bases 310 and limiting members 320 are arranged in a one-to-one correspondence, and the nut at the lower end of the quick-locking bolt 330 is tightened and fixed to the limiting member 320.

[0151] In this embodiment, the limiting member 320 is a metal part, which is welded to the outer peripheral wall of the crucible.

[0152] Specifically, the quick-lock bolt 330 includes a bolt shank, a retaining ring 332, and a quick-lock nut 331. It is understood that those skilled in the art know how to implement the quick-lock bolt 330, and will not be described further here.

[0153] In another embodiment, during the high-temperature calcination of the semi-finished lithium-ion battery anode material, a metal crucible filled with the semi-finished lithium-ion battery anode material needs to be sent into a tunnel kiln for high-temperature calcination. To facilitate the transportation of the metal crucible, at least two hooks 340 are evenly distributed on the outer peripheral wall of the metal crucible. The limiting member 320 and the hooks 340 are spaced apart from each other in the circumferential direction of the metal crucible. The hooks 340 are hooked by an electric hoist, a cantilever crane or a crane, and the metal crucible filled with the semi-finished lithium-ion battery anode material is placed on a kiln car and sent into the tunnel kiln for high-temperature calcination.

[0154] In this embodiment, the limiting member 320, base 310, quick-lock bolt 330 and hook 340 are made of the same material as the crucible metal liner 101, and the surfaces of the limiting member 320, base 310, quick-lock bolt 330 and hook 340 are all covered with a crucible assembly isolation layer, which has the same composition as the crucible isolation layer 102.

[0155] In this embodiment, when lifting the metal crucible, in order to increase the stability of the connection between the metal crucible and the electric hoist, cantilever crane or gantry crane, at least two sets of hooks 340 are evenly distributed on the outer peripheral wall of the metal crucible. Each set of hooks 340 includes two hooks 340 that are spaced apart from each other in the circumferential direction of the metal crucible.

[0156] Furthermore, it is understood that the crucible assembly in this embodiment includes the aforementioned metal crucible, crucible and lid. The specific structure of the metal crucible and the lid is as described in the above embodiments. Since this crucible assembly adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0157] It should be noted that in this embodiment and other embodiments, the oxygen content inside the metal crucible is very low after the material is filled. The small amount and trace amount of oxygen in the kiln are also difficult to enter the crucible, especially difficult to reach the space between the material and the inner wall of the crucible. Therefore, the carbon coating or graphite coating is difficult to be oxidized.

[0158] When a composite coating is formed by chemical vapor deposition of silicon carbide film together with carbon coating or graphite coating, the carbon coating or graphite coating covers the surface of the chemical vapor deposition silicon carbide film, which is more robust and has better wear resistance than the method of carbon coating or graphite coating directly covering the metal substrate.

[0159] Here, the chemical vapor deposition silicon carbide film refers to the crucible chemical vapor deposition silicon carbide film 500, the cover chemical vapor deposition silicon carbide film 600, and the crucible assembly isolation layer;

[0160] The carbon coating or graphite coating refers to the crucible carbon coating or crucible graphite coating 400, the cap carbon coating or cap graphite coating 700, and the crucible assembly isolation layer.

[0161] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for manufacturing a metal crucible and a crucible lid, characterized in that, The method includes: The crucible metal body and bottom are obtained using a stainless steel plate with a heat resistance temperature greater than 950℃. The crucible metal body is welded to the bottom of the cylinder to obtain a crucible metal liner; A crucible isolation layer is applied to the entire surface of the crucible metal liner to obtain the crucible body. The crucible isolation layer is used to prevent the crucible metal liner from oxidizing or corroding under high temperature open flame and to avoid direct contact between the crucible metal liner and the lithium-ion battery negative electrode material. The step of covering the entire surface of the crucible metal liner with a crucible isolation layer includes: After covering the entire surface of the crucible metal liner with chemical vapor deposition of silicon carbide to form a crucible chemical vapor deposition silicon carbide film, a carbon coating or a graphite coating is then applied to the inner surface of the crucible metal liner to form a crucible carbon coating or a crucible graphite coating. Wherein, the crucible carbon coating or crucible graphite coating covers the entire surface of the crucible chemical vapor deposition silicon carbide film located inside the crucible metal liner to obtain the crucible isolation layer; A stainless steel plate with a heat resistance temperature greater than 950℃ is cut into a cover plate to obtain the cover body. A stainless steel sidewall of the same material is welded vertically around the periphery of the cover plate to form a semi-finished cover that is closed on one side. An opening is formed on one closed side of the crucible lid semi-finished product, and a stainless steel breathable grid with a heat resistance temperature greater than 950°C is horizontally welded to the inner wall of the crucible lid semi-finished product to obtain a crucible lid metal liner. A cover isolation layer is applied to the entire surface of the cover metal liner to obtain the cover body, wherein the cover isolation layer is used to prevent the cover metal liner from oxidizing or corroding under high temperature open flame. The step of covering the entire surface of the cover metal liner with a cover isolation layer includes: After covering the entire surface of the cover metal liner with chemical vapor deposition to form a crucible chemical vapor deposition silicon carbide film, a carbon coating or a graphite coating is then applied to the inner surface of the cover metal liner to obtain a cover carbon coating or a cover graphite coating. The cover carbon coating or cover graphite coating covers the entire surface of the cover chemical vapor deposition silicon carbide film located inside the cover metal liner to obtain the cover isolation layer.

2. The method for manufacturing the metal crucible and crucible lid as described in claim 1, characterized in that, The thickness of the stainless steel plate is 2mm to 8mm.

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