A thermoelectric refrigeration element resistant to electrochemical corrosion in wet heat and a preparation method thereof, and a thermoelectric refrigeration device

Abstract

The application relates to the technical field of thermoelectric refrigerators, and discloses a thermoelectric chemical corrosion-resistant thermoelectric refrigeration element, a preparation method thereof and a thermoelectric refrigeration device. The element comprises a thermoelectric arm, a metal layer and a conductive paste layer between the thermoelectric arm and the metal layer, and the Fermi energy level of the conductive paste layer is between the thermoelectric arm and the metal barrier layer. The element can significantly improve the service life of the thermoelectric refrigeration device in a high-temperature and high-humidity environment. The conductive paste layer can disperse the potential difference after the formation of a primary battery, can significantly reduce the local electric field intensity, can redistribute dynamic charges, can quickly balance the electrochemical potential, can significantly reduce the driving voltage of the primary battery, can significantly reduce the corrosion of the primary battery to the metal barrier layer, and can significantly improve the service life of the thermoelectric refrigerator in a high-temperature and high-humidity environment.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric cooler technology, and in particular to a thermoelectric cooling element resistant to damp heat and electrochemical corrosion, its preparation method, and a thermoelectric cooling device. Background Technology

[0002] The core component of a thermoelectric cooler is a thermoelectric arm connected in series with electrodes. The thermoelectric arm is composed of P-type and N-type semiconductors, and traditionally, the thermoelectric arm and electrodes are connected by a metal barrier layer and solder. Those skilled in the art have found that traditional thermoelectric coolers have extremely short lifespans when used in high-temperature and high-humidity environments. Further research revealed that under these conditions, the metal barrier layer, the thermoelectric arm, and the solder form a dissimilar metal galvanic cell. The metal barrier layer, acting as the anode, is rapidly consumed and decomposed under electrochemical corrosion. Furthermore, the application of an external DC bias during operation drives metal ions to migrate towards the anode, accelerating the electrochemical reaction and further accelerating the consumption of the metal barrier layer.

[0003] To address the aforementioned problems, those skilled in the art have proposed technical solutions involving the application of protective layers to thermoelectric cooler elements. For example, CN104890325B discloses a protective coating for thermoelectric materials or devices, which involves applying a ceramic protective layer to the surface of the thermoelectric device. Another example is CN121182348A, which discloses a nano-modified thermally conductive, three-proof, insulating organic adhesive composition and its preparation method. This material can be used as a coating for thermoelectric elements, providing moisture-proof, mildew-proof, and salt spray-proof functions. After in-depth research into the above, this invention has found that current protective measures primarily protect thermoelectric elements externally. However, in actual use, the thermal expansion coefficients of the metal barrier layer and the thermoelectric arm differ. Therefore, after prolonged temperature changes, cracks will form in the external protective layer. In high-temperature and high-humidity environments, moisture can penetrate the thermoelectric element through these cracks, causing the external barrier to fail. Therefore, implementing protective measures inside the thermoelectric cooler is crucial for improving its lifespan. Summary of the Invention

[0004] The purpose of this invention is to improve the service life of thermoelectric coolers.

[0005] This invention incorporates a conductive paste layer between the thermoelectric arm and the metal barrier layer. The Fermi level of the conductive paste layer lies between the thermoelectric arm and the metal barrier layer. The conductive paste layer smooths the contact potential gradient and reduces the interfacial electric field strength. The conductive particles in the conductive paste layer have dynamic charge distribution capabilities, absorbing / releasing electrons to balance the electrochemical potential. This allows the metal barrier layer and the thermoelectric arm to quickly reach a quasi-equilibrium state, significantly reducing the local electric field strength and the galvanic cell driving voltage, significantly slowing down the consumption of the metal barrier layer, and significantly improving the service life of the thermoelectric cooler in high-temperature and high-humidity environments.

[0006] The specific technical solution of this invention is as follows: A thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm, a metal layer, and a conductive paste layer composited between the thermoelectric arm and the metal layer; in terms of Fermi level, the thermoelectric arm > conductive paste layer > metal barrier layer.

[0007] Preferably, the metal barrier layer is one of nickel and nickel-phosphorus alloy.

[0008] Preferably, the thickness of the metal barrier layer is >2μm.

[0009] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles and organic binder are made into a slurry; (2) The slurry is coated onto the surface of the thermoelectric arm and cured to form a conductive slurry layer; (3) A metal barrier layer is set on the conductive paste layer to make a thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion.

[0010] Preferably, the conductive particles are graphite powder and carbon black, and the organic binder is an epoxy organic binder.

[0011] Preferably, by mass percentage, the graphite powder is 60-70 wt%, the carbon black is 10-15 wt%, and the organic binder is 15-25 wt%.

[0012] Preferably, the graphite powder has a particle size of 5~10μm, and the carbon black has a particle size of 30~50μm.

[0013] Preferred curing conditions include: an inert gas atmosphere, a temperature of 120~150℃, and a time of 30~60min.

[0014] Preferably, the coating is applied by screen printing, and the coating thickness is 10~30μm.

[0015] Preferably, the metal barrier layer is formed by electroplating, chemical plating, or plasma spraying.

[0016] A thermoelectric refrigeration device includes the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion and electrodes of the thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion connected in series.

[0017] Existing thermoelectric coolers require a protective layer to prevent water and salt contamination when used in high-temperature and high-humidity environments. However, the thermal expansion coefficients of the metal barrier layer and the thermoelectric arm differ, leading to cracks in the protective layer after prolonged temperature control. Water accumulates through the microchannels formed by these cracks and enters the thermoelectric cooler, causing it to fail. To address this issue, this invention incorporates a conductive paste layer between the thermoelectric arm and the metal barrier layer. The Fermi level of this conductive paste layer lies between the two layers. When water enters the thermoelectric cooler, it forms an electrolyte, creating a galvanic cell between the metal barrier layer and the thermoelectric arm. The conductive paste layer disperses abrupt potential differences along its thickness, reducing the local electric field strength. Furthermore, the conductive particles possess dynamic charge redistribution capabilities, absorbing / releasing electrons to balance the system's electrochemical potential. This allows the metal barrier layer and the thermoelectric arm to quickly reach a quasi-equilibrium state, reducing the driving voltage of the galvanic cell and significantly minimizing its corrosive effect on the metal barrier layer. In addition, organic binders can buffer thermal stress and inhibit the initiation of microcracks.

[0018] Compared with the prior art, this application has the following technical effects: This invention incorporates a conductive paste layer with a Fermi level between the metal barrier layer and the thermoelectric arm. This conductive paste layer can disperse the abrupt potential difference after the formation of the galvanic cell, significantly reducing the local electric field strength. Furthermore, the conductive paste layer can redistribute dynamic charges, rapidly balancing the electrochemical potential and significantly reducing the driving voltage of the galvanic cell. It also significantly reduces the corrosive effect of the galvanic cell on the metal barrier layer, and significantly improves the service life of the thermoelectric cooler in high-temperature and high-humidity environments. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a thermoelectric refrigeration device. In the figure, there is a thermoelectric refrigeration element 1 resistant to damp heat and electrochemical corrosion, a thermoelectric arm 101, a metal barrier layer 102, a conductive paste layer 103, an electrode 2, a Sn layer 3, a solder layer 4, and a substrate 5. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments.

[0021] To better understand the content of this invention, further explanation is provided below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0022] Example 1:

[0023] like Figure 1As shown, a thermoelectric cooling device includes a thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion and an electrode 2 connected in series with the thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion. The thermoelectric cooling element is provided with a Sn layer 3, and a solder layer 4 is provided on the Sn layer. The solder layer connects the electrode and the Sn layer. The electrode is disposed on a substrate 5. The thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm 101, a metal barrier layer 102, and a conductive paste layer 103 disposed between the thermoelectric arm and the metal barrier layer.

[0024] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles (60 wt% graphite powder and 15 wt% carbon black) and the organic binder (25 wt% bisphenol F epoxy resin) are mixed evenly to form a slurry; (2) The paste was coated on the thermoelectric arm by screen printing. The coating thickness was 15μm. The coated paste was then cured at 130°C for 45min under an argon atmosphere to form a conductive paste layer. The specific steps of the screen printing process were as follows: Before printing, the thermoelectric arm grains were ultrasonically cleaned for 5min, then dried with nitrogen, and treated with UV ozone for 10min to enhance the surface energy. The screen printing mesh number was 250 mesh (40μm wire diameter). The printing parameters were: squeegee angle 65 degrees, squeegee pressure 0.4Mpa, printing speed 70mm / s. After printing, the screen was left to stand at room temperature for 8min, and then cured at 130°C for 45min under nitrogen protection. (3) A metal barrier layer (Ni-P alloy, 3 μm thick, 10 wt% phosphorus content) is chemically plated onto the cured conductive paste layer to form a thermoelectric cooling element resistant to damp heat electrochemical corrosion. The chemical plating steps are as follows: ultrasonic cleaning with acetone solvent (cleaning parameters 50 kHz, 5 min) dissolves and removes free epoxy resin, dispersant, etc. from the surface of the conductive paste layer; the conductive paste layer is treated with degreasing solution (20 g / L NaOH, 15 g / L Na2CO3 and 2 g / L OP-10 emulsifier) ​​at 55 °C for 5 min; and micro-etching solution (10 g / L KMnO4 and 20 g / L NaOH) is used at 60 °C. The conductive paste layer was treated for 5 minutes to change its surface from smooth to uniformly matte. The active surface of the conductive paste layer was neutralized and reduced using a neutralization solution (5% H2SO4 and 10 g / L NaHSO3) at room temperature for 2 minutes. The conductive paste layer was sensitized using a sensitizing solution (10 g / L SnCl2 and 20 mL / L HCl) at room temperature for 3 minutes. The conductive paste layer was activated using an activation solution (0.1 g / L PdCl2 and 10 mL / L HCl) at room temperature for 3 minutes. The conductive paste layer was rinsed with deionized water 3 times, 2 minutes each time. The nickel sulfate plating solution (pH 4.7) was used for plating at 85 degrees Celsius for 20 minutes.

[0025] Example 2:

[0026] like Figure 1 As shown, a thermoelectric cooling device includes a thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion and an electrode 2 connected in series with the thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion. The thermoelectric cooling element is provided with a Sn layer 3, and a solder layer 4 is provided on the Sn layer. The solder layer connects the electrode and the Sn layer. The electrode is disposed on a substrate 5. The thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm 101, a metal barrier layer 102, and a conductive paste layer 103 disposed between the thermoelectric arm and the metal barrier layer.

[0027] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles (65 wt% graphite powder and 10 wt% carbon black) and the organic binder (25 wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste was coated on the thermoelectric arm by screen printing. The coating thickness was 10μm. The coated paste was then cured at 130°C for 45min under argon atmosphere to form a conductive paste layer. The specific steps of the screen printing coating process were as follows: Before printing, the thermoelectric arm grains were ultrasonically cleaned for 5min, then dried with nitrogen, and treated with UV ozone for 10min to enhance the surface energy. The screen printing mesh number was 250 mesh (40μm wire diameter). The printing parameters were: squeegee angle 65 degrees, squeegee pressure 0.4Mpa, printing speed 70mm / s. After printing, the screen was left to stand at room temperature for 8min, and then cured at 130°C for 45min under nitrogen protection. (3) A metal barrier layer (Ni-P alloy, 3 μm thick, 10 wt% phosphorus content) is chemically plated on the conductive paste layer to form a thermoelectric cooling element resistant to damp heat electrochemical corrosion. The chemical plating steps are as follows: ultrasonic cleaning with acetone solvent (cleaning parameters 50 kHz, 5 min) dissolves and removes free epoxy resin, dispersant, etc. from the surface of the conductive paste layer; the conductive paste layer is treated with degreasing solution (20 g / L NaOH, 15 g / L Na2CO3 and 2 g / L OP-10 emulsifier) ​​at 55 °C for 5 min; and micro-etching solution (10 g / L KMnO4 and 20 g / L NaOH) is used at 60 °C. The conductive paste layer was treated for 5 minutes to change its surface from smooth to uniformly matte; the active surface of the conductive paste layer was neutralized and reduced using a neutralization solution (5% H2SO4 and 10 g / L NaHSO3) at room temperature for 2 minutes; the conductive paste layer was sensitized using a sensitizing solution (10 g / L SnCl2 and 20 mL / L HCl) at room temperature for 3 minutes; the conductive paste layer was activated using an activation solution (0.1 g / L PdCl2 and 10 mL / L HCl) at room temperature for 3 minutes; the conductive paste layer was rinsed three times with deionized water for 2 minutes each time; and the nickel sulfate plating solution (pH 4.7) was used for plating at 85 degrees Celsius for 20 minutes.

[0028] Example 3:

[0029] like Figure 1 As shown, a thermoelectric cooling device includes a thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion and an electrode 2 connected in series with the thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion. The thermoelectric cooling element is provided with a Sn layer 3, and a solder layer 4 is provided on the Sn layer. The solder layer connects the electrode and the Sn layer. The electrode is disposed on a substrate 5. The thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm 101, a metal barrier layer 102, and a conductive paste layer 103 disposed between the thermoelectric arm and the metal barrier layer.

[0030] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles (70 wt% graphite powder and 10 wt% carbon black) and the organic binder (20 wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste was coated on the thermoelectric arm by screen printing. The coating thickness was 30μm. The coated paste was then cured at 150℃ for 30min under argon atmosphere to form a conductive paste layer. The specific steps of the screen printing coating process were as follows: Before printing, the thermoelectric arm grains were ultrasonically cleaned for 5min, then dried with nitrogen, and treated with UV ozone for 10min to enhance the surface energy. The screen mesh number was 250 mesh (40μm wire diameter). The printing parameters were: squeegee angle 65 degrees, squeegee pressure 0.4Mpa, printing speed 70mm / s. After printing, the screen was left to stand at room temperature for 8min, and then cured at 130℃ for 45min under nitrogen protection. (3) A metal barrier layer (Ni-P alloy, 3 μm thick, 10 wt% phosphorus content) is chemically plated on the conductive paste layer to form a thermoelectric cooling element resistant to damp heat electrochemical corrosion. The chemical plating steps are as follows: ultrasonic cleaning with acetone solvent (cleaning parameters 50 kHz, 5 min) dissolves and removes free epoxy resin, dispersant, etc. from the surface of the conductive paste layer; the conductive paste layer is treated with degreasing solution (20 g / L NaOH, 15 g / L Na2CO3 and 2 g / L OP-10 emulsifier) ​​at 55 °C for 5 min; and micro-etching solution (10 g / L KMnO4 and 20 g / L NaOH) is used at 60 °C. The conductive paste layer was treated for 5 minutes to change its surface from smooth to uniformly matte; the active surface of the conductive paste layer was neutralized and reduced using a neutralization solution (5% H2SO4 and 10 g / L NaHSO3) at room temperature for 2 minutes; the conductive paste layer was sensitized using a sensitizing solution (10 g / L SnCl2 and 20 mL / L HCl) at room temperature for 3 minutes; the conductive paste layer was activated using an activation solution (0.1 g / L PdCl2 and 10 mL / L HCl) at room temperature for 3 minutes; the conductive paste layer was rinsed three times with deionized water for 2 minutes each time; and the nickel sulfate plating solution (pH 4.7) was used for plating at 85 degrees Celsius for 20 minutes.

[0031] Example 4:

[0032] like Figure 1 As shown, a thermoelectric cooling device includes a thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion and an electrode 2 connected in series with the thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion. The thermoelectric cooling element is provided with a Sn layer 3, and a solder layer 4 is provided on the Sn layer. The solder layer connects the electrode and the Sn layer. The electrode is disposed on a substrate 5. The thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm 101, a metal barrier layer 102, and a conductive paste layer 103 disposed between the thermoelectric arm and the metal barrier layer.

[0033] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles (70 wt% graphite powder and 10 wt% carbon black) and the organic binder (20 wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste was coated on the thermoelectric arm by screen printing. The coating thickness was 15μm. The coated paste was then cured at 120℃ for 60min under argon atmosphere to form a conductive paste layer. The specific steps of the screen printing coating process were as follows: Before printing, the thermoelectric arm grains were ultrasonically cleaned for 5min, then dried with nitrogen, and treated with UV ozone for 10min to enhance the surface energy. The screen mesh number was 250 mesh (40μm wire diameter). The printing parameters were: squeegee angle 65 degrees, squeegee pressure 0.4Mpa, printing speed 70mm / s. After printing, the screen was left to stand at room temperature for 8min, and then cured at 130℃ for 45min under nitrogen protection. (3) Electroplating a metal barrier layer (Ni, 3 μm thick) onto the conductive paste layer to fabricate a thermoelectric cooling element resistant to damp heat and electrochemical corrosion. The electroplating steps are as follows: ultrasonic cleaning with acetone solvent (cleaning parameters 50 kHz, 5 min) to remove organic residues from the surface of the conductive paste layer; O2 plasma cleaning, radio frequency plasma cleaning, power 150 W, cleaning time 5 min for the conductive paste layer; using micro-etching solution (10 g / L KMnO4 and 20 g / L NaOH) to treat the conductive paste layer at 60 °C for 5 min to change the surface from smooth to uniform matte; using neutralization solution (5% volume ratio H2SO4 and 10 g / L NaHSO3) to neutralize and reduce the active surface of the conductive paste layer at room temperature for 2 min; and using a current density of 3 A / dm at a temperature of 55 °C. 2 The conductive slurry was electrolyzed for degreasing (anodic electrolysis for 2 min, cathodic electrolysis for 3 min) using a degreasing solution consisting of 30 g / L NaOH, 20 g / L Na2CO3, 20 g / L Na3PO4, and 2 g / L surfactant. The conductive slurry was then activated by acid washing with 10% (v / v) H2SO4 at room temperature for 15 s. The slurry was rinsed three times with deionized water for 2 min each time, and then dried with nitrogen. Finally, an aminosulfonic acid-Ni system (pH 3.5–4.0) was used at 55°C and a current density of 2 A / dm³. 2 Electroplating for 20 minutes under the specified conditions.

[0034] Example 5:

[0035] like Figure 1As shown, a thermoelectric cooling device includes a thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion and an electrode 2 connected in series with the thermoelectric cooling element 1 resistant to damp heat and electrochemical corrosion. The thermoelectric cooling element is provided with a Sn layer 3, and a solder layer 4 is provided on the Sn layer. The solder layer connects the electrode and the Sn layer. The electrode is disposed on a substrate 5. The thermoelectric cooling element resistant to damp heat and electrochemical corrosion includes a thermoelectric arm 101, a metal barrier layer 102, and a conductive paste layer 103 disposed between the thermoelectric arm and the metal barrier layer.

[0036] A method for preparing the above-mentioned thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion includes the following steps: (1) The conductive particles (70 wt% graphite powder and 10 wt% carbon black) and the organic binder (20 wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste was coated on the thermoelectric arm by screen printing. The coating thickness was 15μm. The coated paste was then cured at 120℃ for 60min under argon atmosphere to form a conductive paste layer. The specific steps of the screen printing coating process were as follows: Before printing, the thermoelectric arm grains were ultrasonically cleaned for 5min, then dried with nitrogen, and treated with UV ozone for 10min to enhance the surface energy. The screen mesh number was 250 mesh (40μm wire diameter). The printing parameters were: squeegee angle 65 degrees, squeegee pressure 0.4Mpa, printing speed 70mm / s. After printing, the screen was left to stand at room temperature for 8min, and then cured at 130℃ for 45min under nitrogen protection. (3) Plasma spraying of a metal barrier layer (the metal barrier layer is Ni, with a thickness of 3 μm and a phosphorus content of 10 wt%) on the conductive paste layer to make a thermoelectric cooling element resistant to damp heat electrochemical corrosion. The plasma spraying steps are as follows: ultrasonically clean the conductive paste layer with acetone solvent for 5 min; use alumina particles with a particle size of 46~80 mesh to sandblast and roughen the conductive paste layer under a pressure of 0.5 MPa and a temperature of 75~90° to make the surface roughness of the conductive paste layer reach 3~6 μm; use high-purity Ni powder (Ni≥99.5% with a particle size of 45~100 μm) to plasma spray the conductive paste layer (spraying distance 100 mm, spray gun moving speed 400 mm / s, total coating thickness 20 μm, completed in 3 passes, each pass 5~8 μm) Ni.

[0037] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that no conductive paste layer was provided, while the other conditions were the same as in Example 1.

[0038] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the Fermi level of the conductive paste layer is lower than that of the metal barrier layer, and fluorinated graphite powder is used instead of ordinary graphite powder, including the following steps: (1) The conductive particles (75wt% fluorinated graphite powder) and the organic binder (25wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste is coated on the thermoelectric arm by screen printing with a coating thickness of 15μm. The coated paste is then cured at 130℃ for 45min under an argon atmosphere to form a conductive paste layer. (3) A thermoelectric cooling element resistant to damp heat and electrochemical corrosion is made by chemically plating a metal barrier layer on the conductive paste layer (the metal barrier layer is a Ni-P alloy with a thickness of 3 μm and a phosphorus content of 10 wt%).

[0039] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the Fermi level of the conductive paste layer is greater than the Fermi level of the thermoelectric arm, and Zn powder is used instead of graphite powder as the conductive filler; the steps include: (1) The conductive particles (75wt% Zn powder) and the organic binder (25wt% bisphenol F type epoxy resin) are mixed evenly to form a slurry; (2) The paste is coated on the thermoelectric arm by screen printing with a coating thickness of 15μm. The coated paste is then cured at 130℃ for 45min under an argon atmosphere to form a conductive paste layer. (3) A thermoelectric cooling element resistant to damp heat and electrochemical corrosion is made by chemically plating a metal barrier layer on the conductive paste layer (the metal barrier layer is a Ni-P alloy with a thickness of 3 μm and a phosphorus content of 10 wt%).

[0040] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the conductive particles in the conductive paste layer are metal particles, and the Fermi level of the conductive paste layer is located between the Ni metal layer and the thermoelectric arm material. Cu powder is used instead of graphite, including the following steps:

[0041] (1) The conductive particles (75 wt%) and the organic binder (25 wt% bisphenol F epoxy resin) are mixed evenly to form a slurry; (2) The paste is coated on the thermoelectric arm by screen printing with a coating thickness of 15μm. The coated paste is then cured at 130℃ for 45min under an argon atmosphere to form a conductive paste layer. (3) A thermoelectric cooling element resistant to damp heat and electrochemical corrosion is made by chemically plating a metal barrier layer on the conductive paste layer (the metal barrier layer is a Ni-P alloy with a thickness of 3 μm and a phosphorus content of 10 wt%).

[0042] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the conductive paste layer uses a conductive organic resin (ionic conductive resin), while all other conditions are the same as in Example 1.

[0043] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that no conductive particles were set in the conductive paste layer, while all other conditions were the same as in Example 1.

[0044] Test example: The thermoelectric refrigeration devices of Examples 1-5 and Comparative Examples 1-5 were tested; test items: short-circuit failure time, barrier layer dissolution rate, resistance change rate, contact resistance; test conditions: temperature 85°C, humidity 85%RH. The test results are shown in Table 1; Table 1 Test Results of Thermoelectric Refrigeration Device in High Temperature and High Humidity Environment As shown in Table 1, the thermoelectric refrigeration device prepared by this invention exhibits excellent resistance to damp heat electrochemical corrosion after 1000 hours of testing under high temperature and high humidity conditions. The dissolution rate of the metal barrier layer is <10%, the resistance change rate is <10%, and the contact resistance is <1μΩ•cm².

[0045] Comparative Example 1 is a thermoelectric refrigeration device without a conductive paste layer. After 400 hours of testing, it experienced device open circuit failure, and the dissolution rate of the metal barrier layer reached 100%. Compared with Comparative Example 1, Example 1 shows that the electrochemical corrosion of the thermoelectric refrigeration device with a conductive paste layer is significantly reduced in high temperature and high humidity environments, and the service life of the thermoelectric refrigeration device is significantly increased.

[0046] The Fermi level of the conductive paste layer in Comparative Example 2 is lower than that of the metal barrier layer. As a result, the conductive buffer layer failed to protect the thermoelectric arm, and the thermoelectric arm corroded, the interface peeled off, and the device failed due to open circuit.

[0047] The Fermi level of the conductive paste layer in Comparative Example 3 is greater than that of the thermoelectric arm. The results showed that the conductive buffer layer did not achieve the protection effect. After 500 hours of double 85 testing, the buffer layer was 100% dissolved, and the device was open-circuited.

[0048] The results of Comparative Examples 2 and 3 show that when the Fermi level of the conductive paste layer is not set between the thermoelectric arm and the metal barrier layer, the electrochemical corrosion of the galvanic cell is enhanced, failing to provide protection. Furthermore, the conductive paste layer itself will dissolve, leading to device open circuit and significantly reducing the service life of the thermoelectric cooler.

[0049] In Comparative Example 4, the conductive particles in the conductive paste layer were metal particles. The results showed that the metal particles would ionize and dissolve in the galvanic cell environment and could not produce significant resistance to damp heat electrochemical corrosion. The above results indicate that the conductive particles in the conductive paste layer need to be non-ionizing and able to keep the Fermi level of the conductive paste layer between the thermoelectric arm and the metal barrier layer in order to significantly improve the resistance to damp heat electrochemical corrosion of the thermoelectric cooler.

[0050] In Comparative Example 5, an ionic conductive resin without added conductive particles was used. The results showed that the ionic conductive resin under an electric field underwent ion migration and severe electrochemical corrosion, making it unsuitable as a conductive buffer layer.

[0051] In Comparative Example 6, no conductive particles were provided, so the thermoelectric refrigeration device could not form a conductive circuit and could not be used.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion, characterized in that, It includes a thermoelectric arm (101), a metal layer (102), and a conductive paste layer (103) between the thermoelectric arm and the metal layer; in terms of Fermi level, the thermoelectric arm > the conductive paste layer > the metal barrier layer.

2. The thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion according to claim 1, characterized in that, The metal barrier layer is one of nickel and nickel-phosphorus alloy.

3. The thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion according to claim 1 or 2, characterized in that, The thickness of the metal barrier layer is >2μm.

4. A method for preparing a thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The conductive particles and organic binder are made into a slurry; (2) The slurry is coated onto the surface of the thermoelectric arm and cured to form a conductive slurry layer; (3) A metal barrier layer is set on the conductive paste layer to make a thermoelectric refrigeration element resistant to damp heat and electrochemical corrosion.

5. The preparation method according to claim 4, characterized in that, The conductive particles are graphite powder and carbon black, and the organic binder is an epoxy organic binder.

6. The preparation method according to claim 5, characterized in that, By weight percentage, graphite powder accounts for 60-70 wt%, carbon black accounts for 10-15 wt%, and organic binder accounts for 15-25 wt%.

7. The preparation method according to claim 5 or 6, characterized in that, The particle size of graphite powder is 5~10μm, and the particle size of carbon black is 30~50μm.

8. The preparation method according to claim 4, characterized in that, The curing conditions include: inert gas atmosphere, temperature 120~150℃, and time 30~60min.

9. The preparation method according to claim 4, characterized in that, The coating is applied using screen printing, with a thickness of 10~30μm; the metal barrier layer is applied using one of the following methods: electroplating, chemical plating, or plasma spraying.

10. A thermoelectric refrigeration device, characterized in that, It includes the thermoelectric cooling element (1) resistant to damp heat and electrochemical corrosion as described in any one of claims 1 to 3 and the electrodes (2) of the thermoelectric cooling element resistant to damp heat and electrochemical corrosion in series.

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