Temperature measuring device and temperature measuring system for molten metal lithium and alloy thereof

Abstract

The utility model provides a temperature measuring device and a temperature measuring system for molten metal lithium and alloy thereof, and relates to the field of metallurgical smelting and casting. The temperature measuring device for the molten metal lithium and the molten metal lithium alloy comprises a heat conduction coating, filling layers and a thermocouple sensor, the filling layers comprise a first filling layer and a second filling layer, the cross section of the second filling layer is larger than that of the first filling layer, the first filling layer and the second filling layer form a step shape, and the heat conduction coating is connected with the first filling layer or the second filling layer. One end of the thermocouple sensor is located outside the filling layer, the other end of the thermocouple sensor penetrates through the filling layer and is close to the heat conduction coating, and the heat conduction coating is made of a metal material with the heat conductivity being 80 W / m.K or above. The temperature measuring device for the molten lithium metal and the alloy thereof can accurately conduct the temperature of the molten lithium metal and the alloy thereof under the condition that the molten lithium metal does not corrode the inner wall, meanwhile, the application range of the thermocouple sensor and the temperature measuring device for the molten lithium metal and the alloy thereof can be modified at any position needing temperature measurement, and the application range is wide.

Description

Technical Field

[0001] The utility model relates to the field of metallurgical smelting and casting, and in particular to a temperature measuring device and a temperature measuring system for molten metal lithium and its alloys. Background Art

[0002] As downstream markets increasingly demand higher energy density in lithium-ion batteries, research and development is shifting to lithium metal and its composite materials. Lithium alloys, known as the "ultimate anode material" for lithium-ion batteries due to their high energy density, present numerous challenges in their direct use in existing liquid electrolyte lithium-ion battery systems. The rapid adoption of solid-state electrolytes has made it possible to directly use lithium metal and its composite materials as anode materials in lithium-ion batteries.

[0003] However, the introduction of solid-state electrolytes also brings new problems, such as solid-solid interface contact, low ion conduction efficiency in solid-state electrolytes, and other problems that restrict the commercialization process of metallic lithium and its composite materials. In addition to defects on the technical end, at the upstream raw material preparation end, metallic lithium and its composite materials react more actively with nitrogen and oxygen in the air due to their excessive plasticity. Therefore, process control in the preparation process of lithium-based composite negative electrode materials is very important. However, at present, in the preparation process of metallic lithium and its alloy ingots, more attention is paid to cooling the alloy ingot as a whole to improve the quality ratio of lithium ingots or alloy ingots. For example, the cooling mold described in patent CN218283660U can improve product quality and increase yield, but it does not describe how to accurately control the temperature of the product. It is difficult to judge its cooling effect during actual use. Patent CN202701317U describes a method of preferentially cooling and solidifying the lower half of the product to improve product shrinkage holes, but in actual production, heat itself is transferred from the side walls and bottom, causing the shrinkage holes to deepen further.

[0004] Therefore, in the process of preparing lithium metal and its alloy ingots, in addition to focusing on how to cool the mold, additional consideration should be given to how to improve heat transfer efficiency and how to accurately measure temperature.

[0005] As we all know, there are still many challenges in directly using metallic lithium in solid-state batteries. Lithium alloys also have a high energy density. The appropriate addition of some elements can greatly improve the toughness of the material itself. The fundamental reason for the increase in toughness is that the doping elements and metallic lithium produce intermetallic compounds, and various intermetallic compounds either in the form of dispersion or nucleation and growth hinder the failure of the base material. However, in the process of controlling the doping morphology of intermetallic compounds, heat treatment of alloy ingot products is one of the core process conditions. Therefore, in the process of preparing alloy materials, temperature measurement and monitoring are particularly important. However, there are special problems in the existing lithium-based alloy preparation process.

[0006] For example, currently most molds for lithium metal are made of thick-walled stainless steel. As we all know, stainless steel has good corrosion resistance at low temperatures. The thick walls are used to absorb the heat of the molten lithium and dissipate the heat from the side walls and bottom, so that the molten lithium liquid quickly drops below the solidus. However, for lithium-based alloy ingots with precipitated phases, natural cooling will cause composition segregation and anisotropic orientation inside the cast alloy ingot. Usually, the molten alloy liquid is cooled to room temperature by controlling the temperature of the mold. Therefore, it is necessary to accurately detect the actual temperature of the molten liquid or alloy ingot in the mold. On the other hand, when it is necessary to perform heat treatment modification on the inside of the alloy ingot during the solidification process, accurate temperature measurement becomes even more important.

[0007] In view of this, the utility model proposes a temperature measuring device for accurately measuring the temperature of molten metal lithium and its alloy product ingots. Utility Model Content

[0008] The purpose of the utility model is to provide a temperature measuring device and a temperature measuring system for molten metal lithium and its alloys.

[0009] The embodiment of the present utility model is achieved as follows:

[0010] In the first aspect, the utility model provides a temperature measuring device for molten lithium metal and its alloys, which includes a thermal conductive coating, a filling layer and a thermocouple sensor, the filling layer including a first filling layer and a second filling layer, the cross-section of the second filling layer is larger than that of the first filling layer, the first filling layer and the second filling layer form a stepped shape, the thermal conductive coating is connected to the first filling layer or the second filling layer, one end of the thermocouple sensor is located outside the filling layer, and the other end is arranged in the filling layer and close to the thermal conductive coating, and the material of the thermal conductive coating is a metal material with a thermal conductivity of more than 80W / m·K.

[0011] In an optional embodiment, the material of the thermal conductive coating includes tungsten, zirconium, chromium, iron or nickel.

[0012] In an optional embodiment, the filling layer is made of pure copper, tungsten, molybdenum, zirconium or chromium.

[0013] In an optional embodiment, the area of ​​the thermally conductive coating is greater than or equal to the area of ​​the first filling layer or the second filling layer connected thereto. In a second aspect, the present invention provides a temperature measurement system comprising a mold and a temperature measurement device for molten lithium metal and its alloys as described in any of the aforementioned embodiments, wherein the mold is provided with a mounting hole, and the temperature measurement device for molten lithium metal and its alloys is mounted in the mounting hole.

[0014] In an optional embodiment, the mold includes a casting mold, a lithium alloy smelting kettle or a lithium alloy high-temperature melting reactor.

[0015] In an optional embodiment, when the outer pressure of the side wall of the mold is greater than the inner pressure, the thermal conductive coating layer is connected to the first filling layer.

[0016] In an optional embodiment, the inner pressure of the side wall of the mold is greater than the outer pressure, and the thermal conductive coating layer is connected to the second filling layer.

[0017] In an optional embodiment, there are multiple temperature measuring devices for the molten lithium metal and its alloys, and they are arranged at different positions or heights of the mold.

[0018] The beneficial effects of the embodiments of the present utility model are:

[0019] The temperature measuring device for molten lithium and its alloys provided by the present invention selects a metal material with a thermal conductivity of 80W / m·K or higher as a thermally conductive coating, which not only has excellent thermal conductivity but also has excellent corrosion resistance. This ensures that the temperature of the molten lithium and its alloys is accurately transmitted without the molten lithium corroding the inner wall. Simultaneously, the thermocouple sensor is embedded in the stepped filling layer, which prevents it from directly contacting the molten lithium and its alloys. Therefore, the thermocouple sensor can be selected from common thermocouple sensors on the market, greatly expanding the scope of application of the thermocouple sensor. In addition, the stepped design of the first and second filling layers in the present invention allows the filling layers to be installed in different directions according to the internal and external pressures of the mold, thereby extending the scope of application of the temperature measuring device for molten lithium and its alloys provided by the present invention. The mold in the temperature measuring system provided by the present invention is not restricted by the mold material, size, presence or absence of an interlayer, cooling circulation system, etc., and can be modified at any location where temperature measurement is required, thus having a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of a first structural embodiment of a temperature measuring device for molten lithium and its alloys provided by the first embodiment of the present invention;

[0022] Figure 2 A schematic diagram of a second structure of the temperature measuring device for molten lithium and its alloys provided in the first embodiment of the present utility model;

[0023] Figure 3 This is a structural diagram of a temperature measurement system provided in the second embodiment of the present invention.

[0024] Icon: 100- Temperature measuring device for molten metal lithium and its alloys;

[0025] 110 - thermal conductive coating; 120 - filling layer; 121 - first filling layer; 122 - second filling layer; 130 - thermocouple sensor;

[0026] 200-temperature measurement system; 210-mold. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0030] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is typically placed when in use. These terms are intended solely to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0032] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0033] First embodiment

[0034] Please refer to Figure 1 and Figure 2 This embodiment provides a temperature measurement device 100 for molten lithium metal and its alloys, which includes a thermally conductive coating 110, a filling layer 120, and a thermocouple sensor 130. The filling layer 120 includes a first filling layer 121 and a second filling layer 122. The second filling layer 122 has a larger cross-section than the first filling layer 121. The first filling layer 121 and the second filling layer 122 form a stepped shape. The thermally conductive coating 110 is connected to the first filling layer 121 or the second filling layer 122. One end of the thermocouple sensor 130 is located outside the filling layer 120, and the other end is disposed within the filling layer 120 and close to the thermally conductive coating 110.

[0035] Among them, the thermal conductive coating 110 is in direct contact with molten metallic lithium and its alloys. Since molten metallic lithium or lithium alloy liquid is extremely corrosive to some metal materials, the thermal conductive coating 110 is made of a material with good thermal conductivity and corrosion resistance to ensure that the molten metallic lithium will not corrode the inner wall. The selection of its material is particularly important. The appropriate material for the thermal conductive coating 110 is selected by combining the thermal conductivity of each metal material and its ability to form a phase with metallic lithium at high temperature.

[0036] Specifically, based on the thermal conductivity of various common metal materials, copper's thermal conductivity is second only to silver. However, it is relatively inexpensive and easier to process. However, molten lithium or lithium alloys are extremely corrosive to copper, forming lithium-copper intermetallic compounds that increase impurities in the product. Therefore, copper is not suitable for the thermally conductive coating 110 in this embodiment.

[0037] Therefore, in this example, all pure metal materials were cross-compared in terms of their corrosion resistance to molten lithium and thermal conductivity. Twenty pure metal materials were selected with thermal conductivity (or thermal conductivity coefficient) exceeding 80 W / m·K (80.4 W / m·K for ferrite). Each of these materials was then examined to determine whether they would form intermetallic compounds with molten lithium at high temperatures. Ruthenium has a low melting point and is relatively rare, so no data has been reported. The lowest temperatures at which the remaining elements form intermetallic compounds or solid solutions with solid and liquid lithium are shown in the table below:

[0038]

[0039]

[0040] Note: When it can form an intermetallic compound or solid solution phase with metallic lithium at room temperature, it is marked as 0.

[0041] As can be seen from the above table, the thermal conductive coating 110 in contact with the molten metal lithium can be made of tungsten, zirconium, chromium, iron, and nickel. However, pure iron is prone to rust when used as a mold 210 or a reactor and is not a preferred option. When the nickel element is at 800°C, liquid nickel will melt into the liquid lithium, which will consume the thermal conductive coating 110 to a certain extent. Therefore, it can be used as an alloy system with a casting temperature below 800°C.

[0042] Therefore, the material of the thermal conductive coating 110 can be high-purity tungsten (W), zirconium (Zr), chromium (Cr), iron (Fe), and nickel (Ni), preferably tungsten (W), zirconium (Zr), chromium (Cr), and iron (Fe), and more preferably tungsten (W), zirconium (Zr), and chromium (Cr).

[0043] Filling layer 120 is primarily designed to transfer heat and avoid direct contact with molten lithium metal and its alloys. Therefore, filling layer 120 is constructed from pure copper, tungsten, molybdenum, zirconium, or chromium. When using filling layer 120 at temperatures above 800°C (approximately 0.8Tm for copper), thermally conductive materials with higher melting points, such as tungsten, molybdenum, zirconium, and chromium, should be considered.

[0044] Furthermore, since the temperature measuring device 100 for molten metal lithium and its alloys in this embodiment is suitable for various mold 210 scenarios, when there is a certain pressure difference inside and outside the mold 210, the directions of the first filling layer 121 and the second filling layer 122 in the filling layer 120 can be adjusted as needed so that the device will not be squeezed out when the pressure is too high.

[0045] In this embodiment, the stepped design consisting of the first filling layer 121 and the second filling layer 122 allows the filling layer 120 to change its installation direction according to the different internal and external pressures of the mold 210, so that the temperature measuring device 100 for molten metal lithium and its alloys in this embodiment has a wider range of applications.

[0046] In this embodiment, the area of ​​the thermally conductive coating 110 is greater than or equal to the area of ​​the first filling layer 121 or the second filling layer 122 connected thereto. The provision of the thermally conductive coating 110 ensures that the filling layer 120 and the thermocouple sensor 130 are not in direct contact with molten lithium metal and its alloys, thereby preventing corrosion of the filling layer 120 and the thermocouple sensor 130 by the molten lithium metal and its alloys. Furthermore, the thickness of the thermally conductive coating 110 can be determined based on practical needs to better protect the filling layer 120 and the thermocouple sensor 130. Furthermore, the thickness of the filling layer 120 is greater than or equal to the thickness of the sidewalls of the mold 210 to ensure that the filling layer 120 and the thermocouple sensor 130 are easier to install in the mold and provide greater stability for the thermocouple sensor 130. The shape of the filling layer 120 is not limited to the convex-shaped structure of this embodiment. In other embodiments, the filling layer 120 can also be an "I"-shaped structure, as long as it can effectively secure the thermocouple sensor 130.

[0047] In this embodiment, the thermocouple sensor 130 selects an appropriate model and specification according to the usage scenario. Since the thermal conductive coating 110 is used to directly contact the molten metal lithium and its alloys in this embodiment, and the thermocouple sensor 130 is embedded in the filling layer 120, the thermocouple sensor 130 is well protected and will not directly contact the molten metal lithium and its alloys. Therefore, the thermocouple sensor 130 can select the common thermocouple sensor 130 on the market, which greatly expands the scope of application of the thermocouple sensor 130.

[0048] Second embodiment

[0049] See also Figure 3 The present invention provides a temperature measurement system 200, which includes a mold 210 and the temperature measurement device 100 for molten metal lithium and its alloys provided in the first embodiment. The mold 210 is provided with a mounting hole, and the temperature measurement device 100 for molten metal lithium and its alloys is installed in the mounting hole.

[0050] In this embodiment, mold 210 includes, but is not limited to, a casting mold 210, a lithium alloy smelting kettle, or a lithium alloy high-temperature melting reactor. Furthermore, mold 210 in this embodiment is not limited to its material, size, presence of interlayers, or cooling system, and can be modified to any location requiring temperature measurement.

[0051] See also Figure 1 When the outer pressure of the side wall of the mold 210 is greater than the inner pressure, the thermal conductive coating layer 110 is connected to the first filling layer 121. Figure 2 , the inner pressure of the side wall of the mold 210 is greater than the outer pressure, and the thermal conductive coating layer 110 is connected to the second filling layer 122 .

[0052] In addition, in order to detect different positions of the mold 210, the number of temperature measuring devices 100 for molten metal lithium and its alloys in this embodiment is multiple, and they are set at different positions or different heights of the mold 210, thereby achieving more accurate temperature detection.

[0053] When installing the temperature measurement device 100 for molten lithium and its alloys on the mold 210, it is first necessary to select the appropriate specifications of the thermocouple sensor 130. Based on the internal and external pressure differential in the application scenario, the wall thickness of the original mold 210 is measured, and the stepped first filling layer 121 and second filling layer 122 are designed based on the wall thickness. According to the size of the filling layer 120, a stepped cavity is opened in the mold 210, and the thermocouple sensor 130 is embedded therein, leaving space for the thermal conductive coating layer 110. Then, the pure copper filling layer 120 is cast. At this time, the filling layer 120, the thermocouple sensor 130, and the mold 210 are in close contact, completing the installation of the filling layer 120 and the thermocouple sensor 130. Finally, the required thermal conductive coating 110 is filled into the inner wall of the mold 210. The thermal conductive coating 110 contacts the filling layer 120, and its area is greater than or equal to the area of ​​the first filling layer 121 or the second filling layer 122 connected to it. It should be understood that the installation method in this embodiment is not limited to the above-described method, as long as the temperature measuring device 100 for molten lithium metal and its alloys can be stably installed on the mold 210 .

[0054] In summary, the temperature measuring device 100 for molten lithium and its alloys provided by the present invention selects a metal material with a thermal conductivity of 80W / m·K or more as the thermal conductive coating 110, which not only has good thermal conductivity but also has good corrosion resistance. It can ensure that the temperature of the molten lithium and its alloys is accurately transmitted without the molten lithium corroding the inner wall. At the same time, the thermocouple sensor 130 is embedded in the stepped filling layer 120, so that it does not directly contact the molten lithium and its alloys. Therefore, the thermocouple sensor 130 can be selected from the common thermocouple sensors 130 on the market, which greatly expands the scope of application of the thermocouple sensor 130. In addition, in the present invention, the stepped design composed of the first filling layer 121 and the second filling layer 122 allows the filling layer 120 to change the installation direction according to the different internal and external pressures of the mold 210, making the scope of application of the temperature measuring device 100 for molten lithium and its alloys in the present invention wider. The mold 210 in the temperature measurement system 200 provided by the present invention is not limited in terms of material, size, presence or absence of interlayer, cooling circulation system, etc. The mold 210 can be modified at any location where temperature measurement is required, and has a wide range of applications.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A temperature measuring device for molten lithium metal and its alloys, characterized in that: It includes a thermal conductive coating, a filling layer and a thermocouple sensor. The filling layer includes a first filling layer and a second filling layer. The cross-section of the second filling layer is larger than that of the first filling layer. The first filling layer and the second filling layer form a stepped shape. The thermal conductive coating is connected to the first filling layer or the second filling layer. One end of the thermocouple sensor is located outside the filling layer, and the other end is arranged in the filling layer and close to the thermal conductive coating. The material of the thermal conductive coating is a metal material with a thermal conductivity of more than 80W / m·K.

2. The temperature measuring device for molten lithium metal and its alloys according to claim 1, characterized in that: The material of the thermal conductive coating includes tungsten, zirconium, chromium, iron or nickel.

3. The temperature measuring device for molten lithium metal and its alloys according to claim 1, characterized in that: The filling layer is made of pure copper, tungsten, molybdenum, zirconium or chromium.

4. The temperature measuring device for molten lithium metal and its alloys according to claim 1, characterized in that: The area of ​​the thermal conductive coating layer is greater than or equal to the area of ​​the first filling layer or the second filling layer connected thereto.

5. A temperature measurement system, characterized in that: It comprises a mold and a temperature measuring device for molten lithium metal and its alloys as claimed in any one of claims 1 to 4. The mold is provided with a mounting hole, and the temperature measuring device for molten lithium metal and its alloys is mounted in the mounting hole.

6. The temperature measurement system according to claim 5, characterized in that: The mold includes a casting mold, a lithium alloy smelting kettle or a lithium alloy high-temperature melting reactor.

7. The temperature measurement system according to claim 5, characterized in that: When the outer pressure of the side wall of the mold is greater than the inner pressure, the heat conductive coating layer is connected to the first filling layer.

8. The temperature measurement system according to claim 5, characterized in that: The inner pressure of the side wall of the mold is greater than the outer pressure, and the heat conductive coating layer is connected to the second filling layer.

9. The temperature measurement system according to claim 5, characterized in that: There are multiple temperature measuring devices for the molten lithium metal and its alloys, and they are arranged at different positions or at different heights of the mold.

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