Thermoelectric device preparation method and thermoelectric device

Abstract

The invention provides a preparation method of a thermoelectric device and the thermoelectric device. The preparation method of the thermoelectric device comprises the following steps: mixing ceramic powder and a polymer column and carrying out die-casting molding; removing the macromolecular columns by adopting a low-temperature sintering technology, and preparing a plurality of microcosmic porous ceramic pieces so as to obtain a thermoelectric device; the high-molecular column and the ceramic powder are mixed and subjected to die-casting molding, and then the high-molecular column is removed to obtain the micro porous thermoelectric device, so that the thermal conductivity and the refrigeration efficiency of the thermoelectric device are effectively improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for preparing a thermoelectric device and a thermoelectric device. Background Art

[0002] In related technologies, the heat dissipation technology used in lithium battery systems has evolved from the first generation of air cooling to the currently commonly used bottom liquid cooling, and the thermoelectric refrigeration technology that uses electronics as a heat conduction technology. However, thermoelectric devices are usually made of ceramic materials, and the thermal conductivity of ceramic materials is low, which limits the heat transfer and affects the cooling efficiency.

[0003] Therefore, the thermoelectric device in the prior art has the technical problem of low thermal conductivity. Summary of the Invention

[0004] The embodiments of the present application provide a method for preparing a thermoelectric device and a thermoelectric device, which can improve the technical problem of low thermal conductivity of thermoelectric devices in the prior art.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a thermoelectric device, comprising:

[0006] Pour ceramic powder into the mold;

[0007] placing a polymer column in the ceramic powder in the mold, and die-casting the ceramic powder and the polymer column to form a ceramic intermediate;

[0008] The polymer pillars are removed by low-temperature sintering technology to prepare a plurality of ceramic pieces with microscopic pores;

[0009] Metal electrode layers are respectively formed on the upper surface and the lower surface of the plurality of ceramic pieces to prepare the thermoelectric device.

[0010] In one embodiment, the step of “removing the polymer pillars by using a low-temperature sintering technique” further includes:

[0011] The sintering temperature of the low-temperature sintering technology is greater than or equal to 500°C and less than or equal to 650°C.

[0012] In one embodiment, the step of “removing the polymer pillars by using a low-temperature sintering technique” further includes:

[0013] The polymer pillars are vaporized and disappear to form a hollow structure in the ceramic piece.

[0014] In one embodiment, the surface of the polymer column is uneven, the inner surface of the hollow structure is uneven, and the hollow structure has a capillary effect.

[0015] In an embodiment, after the step of "molding the ceramic powder and the polymer column by pressure casting", further comprising:

[0016] Embedding a conduit in at least one end of the ceramic intermediate, the conduit being used for vacuumizing and injecting deionized water during the preparation of the thermoelectric device.

[0017] In an embodiment, after the step of "removing the polymer column by low-temperature sintering technology", further comprising:

[0018] Injecting deionized water into the hollow structure of the ceramic piece through the conduit, and freezing to below a first preset temperature.

[0019] In an embodiment, the first preset temperature is -10℃.

[0020] In an embodiment, vacuumizing the ceramic piece through the conduit to lower the boiling point of the deionized water in the ceramic piece to prepare the ceramic piece.

[0021] In an embodiment, sealing the pipe opening of the conduit to make the hollow structure form uniformly distributed micro-cavities.

[0022] In a second aspect, embodiments of the present application provide a use electric device prepared by the preparation method of the thermoelectric device as described in any of the above embodiments, the porosity of the micro-porous structure of the thermoelectric device ranges from 3% to 8%.

[0023] In an embodiment, the thermoelectric device comprises a plurality of N-type ceramic pieces and a plurality of P-type ceramic pieces, two first metal electrodes are formed on the upper surfaces of the plurality of N-type ceramic pieces and the plurality of P-type ceramic pieces, one of the first metal electrodes is electrically connected to the plurality of N-type ceramic pieces, and the other first metal electrode is electrically connected to the plurality of P-type ceramic pieces, a second metal electrode is formed on the lower surfaces of the plurality of N-type ceramic pieces and the plurality of P-type ceramic pieces, and the second metal electrode is electrically connected to the plurality of N-type ceramic pieces and the plurality of P-type ceramic pieces.

[0024] The beneficial effects of embodiments of the present application are:

[0025] By mixing the polymer column and the ceramic powder into a mold and molding by pressure casting, and removing the polymer column by low-temperature sintering technology, a plurality of ceramic pieces with micro-porous structure are prepared, and a thermoelectric device is prepared, the micro-porous structure can effectively improve the thermal conductivity and refrigeration efficiency of the thermoelectric device, thereby alleviating the technical problem of low thermal conductivity of the thermoelectric device in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 1 is a schematic structural diagram of a thermoelectric device provided in an embodiment of the present application;

[0028] Figure 2 Schematic diagram of the working principle of the ceramic component in the thermoelectric device provided by the embodiment of the present application;

[0029] Figure 3 Schematic diagram of the structure of the polymer column in the method for preparing the thermoelectric device provided in the embodiment of the present application;

[0030] Figure 4 A schematic structural diagram of a ceramic intermediate in a method for preparing a thermoelectric device provided in an embodiment of the present application;

[0031] Figure 5 A schematic structural diagram of a ceramic component in a thermoelectric device provided in an embodiment of the present application.

[0032] 1. Thermoelectric device; 2. Ceramic component; 21. N-type ceramic component; 22. P-type ceramic component; 3. Metal electrode layer; 31. First metal electrode; 32. Second metal electrode; 4. Microcavity; 5. Catheter; 6. Polymer column; 7. Ceramic intermediate. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; and "inside" and "outside" refer to the outline of the device.

[0034] In addition, the terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different technical features. The term "plurality" and similar words mean two or more, unless otherwise expressly limited.

[0035] See also Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 The method for preparing the thermoelectric device 1 provided in the embodiment of the present application includes:

[0036] S1: pouring ceramic powder into the mold;

[0037] S2: placing the polymer column 6 in the ceramic powder in the mold, and die-casting the ceramic powder and the polymer column 6 to form a ceramic intermediate 7;

[0038] S3: removing the polymer pillars 6 by low-temperature sintering technology to prepare a plurality of microporous ceramic pieces 2;

[0039] S4: forming metal electrode layers 3 on the upper and lower surfaces of the plurality of ceramic pieces 2 to prepare the thermoelectric device 1 .

[0040] in, Figure 1 The thermoelectric device 1 includes a plurality of ceramic pieces 2 , and the ceramic pieces 2 include an N-type ceramic piece 21 and a P-type ceramic piece 22 .

[0041] The metal electrode layer 3 includes a first metal electrode 31 located on the upper surface and a second metal electrode 32 located on the lower surface.

[0042] The die-cast ceramic intermediate body 7 may be placed in a muffle furnace for low-temperature sintering.

[0043] In this embodiment, the removable polymer pillars 6 are mixed with ceramic powder and die-cast, and then the polymer pillars 6 are removed to obtain a microporous thermoelectric device 1, thereby effectively improving the thermal conductivity and cooling efficiency of the thermoelectric device 1.

[0044] In one embodiment, the step of “removing the polymer pillars 6 by using a low-temperature sintering technique” further includes:

[0045] The sintering temperature of the low-temperature sintering technology is greater than or equal to 500°C and less than or equal to 650°C.

[0046] The polymer column 6 may be made of polyethylene or polypropylene, and the decomposition temperature of polyethylene or polypropylene is in the range of 400°C to 500°C.

[0047] Wherein, the sintering temperature is but not limited to 500°C, 550°C, 600°C, and 650°C.

[0048] It can be understood that when the sintering temperature is less than 500℃, the polymer column 6 cannot be completely pyrolyzed; when the sintering temperature is greater than 650℃, it is easy to cause the ceramic powder to be over-sintered, so that the micro-porous structure collapses.

[0049] It should be noted that the complete pyrolysis of the polymer column 6 without residual carbon can improve the electrical conductivity, and the densification design of the ceramic powder can ensure the mechanical strength of the thermoelectric device 1.

[0050] It is worth noting that the lower the sintering temperature of the low-temperature sintering technology, the lower the energy consumption.

[0051] In the present embodiment, the sintering temperature of the low-temperature sintering technology is greater than or equal to 500℃ and less than or equal to 650℃, so as to ensure that the polymer column 6 is completely pyrolyzed, prevent the ceramic powder from being over-sintered to cause the micro-porous structure to collapse, and maintain the thermoelectric performance.

[0052] In an embodiment, referring to Figure 3 , the step of "removing the polymer column 6 by using the low-temperature sintering technology" further comprises:

[0053] The polymer column 6 is gasified and disappears to form a hollow structure in the ceramic part 2.

[0054] The ceramic intermediate 7 further comprises a binder and a low-molecular-weight component.

[0055] The low-temperature sintering technology is in a stepwise temperature rise.

[0056] The first step is 200℃ to 300℃, so as to remove the binder and the low-molecular-weight component.

[0057] The second step is 400℃ to 450℃, so as to break the molecular main chain of the polymer column 6.

[0058] The second step is 500℃ to 600℃, and a small amount of oxygen or air is introduced to completely oxidize the residual carbon.

[0059] It can be understood that the temperature rise rate of the low-temperature sintering technology in the stepwise temperature rise is less than or equal to 5℃ / min, so as to prevent the hollow structure from being broken due to the rapid decomposition of the polymer column 6.

[0060] It should be noted that the inner wall of the hollow structure formed by the low-temperature sintering is rough and porous, and the rough and porous structure has a plurality of concave-convex structures with a height difference of about 0.8μm.

[0061] In an embodiment, referring to Figure 3 , the surface of the polymer column 6 is uneven, the inner surface of the hollow structure is uneven, and the hollow structure has a capillary effect.

[0062] It can be understood that the hollow structure with an uneven inner wall will exhibit capillary action and can have the function of absorbing liquid, thereby improving the efficiency of heat exchange.

[0063] In one embodiment, after the step of “pressure-casting the ceramic powder and the polymer pillars 6”, the method further includes:

[0064] A conduit 5 is embedded in at least one end of the ceramic intermediate body 7 , and the conduit 5 is used for vacuuming and injecting deionized water during the preparation process of the thermoelectric device 1 .

[0065] The conduit 5 may be a thin steel tube, a copper tube or a stainless steel tube, so that the conduit 5 can withstand low-temperature sintering at 500° C. to 650° C. and does not react with the ceramic powder.

[0066] It is understandable that the embedding position and structural design of the conduit 5 will directly affect the working medium filling efficiency and vacuum maintenance. Evacuating the conduit 5 can eliminate the gas thermal resistance in the microcavity 4 and avoid residual bubbles in the liquid working medium.

[0067] It is understood that a high vacuum can be formed by ice sublimation through a freeze injection method, wherein the temperature range of the freeze injection method is less than or equal to -10°C, and the high vacuum refers to a temperature less than or equal to 10 -3 Pa.

[0068] In one embodiment, see Figure 4 and Figure 5 The step of embedding the conduit 5 at at least one end of the ceramic intermediate body 7 further comprises:

[0069] S10: Preset positioning grooves for the conduit 5 at both ends of the die-casting mold to ensure that the conduit 5 is in close contact with the ceramic powder;

[0070] S20: burying the conduit 5 in the ceramic powder, and placing the conduit 5 parallel to the ceramic powder when the ceramic powder is filled to a first preset height;

[0071] S30: Continue filling the ceramic powder and then vibrating and compacting to reduce the porosity.

[0072] The close contact between the conduit 5 and the ceramic powder means that the gap is less than or equal to 50 μm.

[0073] It is understandable that the surface of the conduit 5 may be roughened to enhance the bonding force with the ceramic powder.

[0074] In one embodiment, after the step of “removing the polymer pillars 6 by adopting a low-temperature sintering technique”, the method further includes:

[0075] Deionized water is injected into the hollow structure of the ceramic member 2 through the conduit 5 and is frozen to below a first preset temperature.

[0076] It can be understood that deionized water can act as a highly efficient heat conducting medium. Since deionized water has a high specific heat capacity and thermal conductivity, it can effectively absorb and transfer heat, thereby enhancing the heat dissipation performance of thermoelectric ceramics. In the hollow structure, deionized water further enhances heat conduction through phase change, thereby improving the overall cooling efficiency of the thermoelectric device 1. Phase change refers to the change in state of deionized water from liquid to solid or liquid to gas.

[0077] It can be understood that the effect of deionized water can form a vacuum cavity, and the vacuum environment can reduce the obstruction of gas molecules to heat conduction, significantly improve the thermal conductivity of the material, and thus enhance heat conduction.

[0078] It can be understood that the role of deionized water can optimize thermal management by utilizing capillary action. The ceramic powder after low-temperature sintering has a hollow structure with an uneven inner wall, which can adsorb and evenly distribute deionized water; this structure can promote the circulation of the working fluid and the rapid diffusion of heat, making the thermoelectric refrigeration process more efficient and stable; among them, the uneven inner wall of the hollow structure is formed by the uneven design of the surface of the polymer column 6.

[0079] It is understandable that the role of deionized water is to prevent impurities from affecting performance. Since ordinary water contains ions and impurities, it may cause electrolysis or corrosion in high temperature or electric field environments, affecting the life of the device; deionized water has been purified and contains almost no conductive ions, which can ensure the long-term stability and reliability of thermoelectric materials.

[0080] In one embodiment, the first preset temperature is -10°C.

[0081] It can be understood that the step of freezing the deionized water to below -10°C is a key step in forming the high vacuum microcavity 4. When the deionized water changes from liquid to solid, it completely solidifies below -10°C and expands in volume, thereby squeezing the residual gas in the microcavity 4 to the outlet of the conduit 5 and being discharged. When the deionized water changes from solid to gas, ice sublimates directly under low pressure to avoid liquid residue. Here, low pressure refers to a temperature less than or equal to 10 -2 Pa; at -10℃, the saturated vapor pressure of ice is 260Pa, which is much lower than the vapor pressure of water at room temperature, making it easier to achieve high vacuum.

[0082] It can be understood that the setting of the first preset temperature of -10°C not only balances the feasibility of the process, making it feasible with conventional refrigeration equipment, but also reduces energy consumption while meeting the vacuum degree standard.

[0083] In one embodiment, the ceramic member 2 is vacuumed through the conduit 5 to reduce the boiling point of the deionized water in the ceramic member 2 , thereby preparing the ceramic member 2 .

[0084] It is understandable that in the preparation process of the thermoelectric device 1, the core purpose of evacuating the ceramic part 2 through the conduit 5 is to significantly reduce the boiling point of deionized water by reducing the air pressure, thereby efficiently removing moisture in a low-temperature environment and ultimately forming a high-vacuum microcavity 4.

[0085] In one embodiment, the orifice of the conduit 5 is sealed so that the hollow structure forms uniformly distributed microcavities 4 .

[0086] The microcavity 4 may be columnar, and the columnar microcavity 4 may guide the heat flow in a direction, reduce the lateral heat diffusion loss, and improve the longitudinal heat conduction performance.

[0087] The microcavity 4 can form a honeycomb-like reinforcement structure to achieve both lightweight and mechanical strength.

[0088] Among them, the microcavity 4 has a capillary effect and can autonomously drive the working medium circulation without the need for external kinetic energy drive.

[0089] The microcavities 4 are evenly distributed, and multiple microcavities 4 are interconnected to form a networked heat channel, which can avoid local hot spots and ensure uniform temperature distribution on the device surface.

[0090] It can be understood that the vacuum environment formed by the microcavity 4 is used to eliminate the obstruction of gas molecules to heat conduction, and the columnar microcavity 4 can guide the heat flow in a direction, reduce the lateral heat diffusion loss, and improve the longitudinal thermal conductivity.

[0091] It can be understood that the microcavity 4 provides storage and circulation space for deionized water, absorbs or releases heat through phase change between liquid and gas, and thus significantly improves the heat transfer capacity.

[0092] It can be understood that the microcavity 4 increases the effective heat transfer area and accelerates the thermal response speed; at the same time, the microcavity 4 can also reduce the amount of ceramic powder used by 20%-30%, reducing the weight of the device while maintaining strength. At the same time, the microcavity 4 can alleviate the thermal stress during low-temperature sintering and reduce the risk of cracking of the ceramic powder.

[0093] The present application provides a method for preparing a thermoelectric device 1, which adopts a polymer template sintering process, has low cost and simple process. The prepared thermoelectric device 1 has excellent cooling efficiency and temperature uniformity, and is particularly suitable for thermal management of lithium battery systems.

[0094] In a second aspect, embodiments of the present application provide a power consuming device prepared by the method for preparing a thermoelectric device 1 as described in any of the above embodiments, wherein the porosity of the micro-porous structure in the thermoelectric device 1 ranges from 3% to 8%.

[0095] The above has introduced the embodiments of the present application in detail, and the principles and implementation manners of the present application have been described by applying specific examples; the above embodiment descriptions are only for helping to understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will have changes; in summary, the content of the present description should not be understood as a limitation on the present application.

Claims

1. A method for preparing a thermoelectric device (1), characterized in that: include: Pour ceramic powder into the mold; Placing a polymer column (6) in the ceramic powder in the mold, and die-casting the ceramic powder and the polymer column (6) to form a ceramic intermediate (7); The polymer pillars (6) are removed by low-temperature sintering technology to prepare a plurality of ceramic pieces (2) having microscopic pores; Metal electrode layers (3) are respectively formed on the upper surface and lower surface of a plurality of the ceramic pieces (2) to prepare the thermoelectric device (1).

2. The method for preparing a thermoelectric device (1) according to claim 1, characterized in that: The step of "removing the polymer pillar (6) by using a low temperature sintering technique" further includes: The sintering temperature of the low-temperature sintering technology is greater than or equal to 500°C and less than or equal to 650°C.

3. The method for preparing a thermoelectric device (1) according to claim 2, characterized in that: The step of "removing the polymer pillar (6) by using a low temperature sintering technique" further includes: The polymer columns (6) are vaporized and disappear to form a hollow structure in the ceramic component (2).

4. The method for preparing a thermoelectric device (1) according to claim 3, characterized in that: The surface of the polymer column (6) is uneven, the inner surface of the hollow structure is uneven, and the hollow structure has a capillary effect.

5. The method for preparing the thermoelectric device (1) according to claim 4, characterized in that: After the step of "pressure-casting the ceramic powder and the polymer column (6), the method further comprises: A conduit (5) is embedded in at least one end of the ceramic intermediate body (7), and the conduit (5) is used for vacuuming and injecting deionized water during the preparation process of the thermoelectric device (1).

6. The method for preparing the thermoelectric device (1) according to claim 5, characterized in that: After the step of "removing the polymer pillar (6) by adopting low temperature sintering technology", the method further comprises: Deionized water is injected into the hollow structure of the ceramic component (2) through the conduit (5) and is frozen to below a first preset temperature.

7. The method for preparing the thermoelectric device (1) according to claim 6, characterized in that: The first preset temperature is -10°C.

8. The method for preparing the thermoelectric device (1) according to claim 6, characterized in that: The ceramic part (2) is vacuumed through the conduit (5) to reduce the boiling point of the deionized water in the ceramic part (2), thereby preparing the ceramic part (2).

9. The method for preparing a thermoelectric device (1) according to claim 8, characterized in that: The orifice of the conduit (5) is sealed so that the hollow structure forms uniformly distributed microcavities (4).

10. A thermoelectric device (1) prepared by the method for preparing a thermoelectric device (1) according to any one of claims 1 to 9, characterized in that: The porosity of the microporous structure in the thermoelectric device (1) ranges from 3% to 8%.

11. The thermoelectric device (1) according to claim 10, characterized in that The thermoelectric device comprises a plurality of N-type ceramic parts (21) and a plurality of P-type ceramic parts (22); two first metal electrodes (31) are formed on the upper surfaces of the plurality of N-type ceramic parts (21) and the plurality of P-type ceramic parts (22); one of the first metal electrodes (31) is electrically connected to the plurality of N-type ceramic parts (21); the other of the first metal electrodes (31) is electrically connected to the plurality of P-type ceramic parts (22); a second metal electrode (32) is formed on the lower surfaces of the plurality of N-type ceramic parts (21) and the plurality of P-type ceramic parts (22); the second metal electrode (22) is electrically connected to both the plurality of N-type ceramic parts (21) and the plurality of P-type ceramic parts (22).

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