A Prussian blue-graphite electrode sheet, its preparation method, and an assembled thermoelectric device.

Abstract

This invention discloses a Prussian blue-graphite electrode sheet, its preparation method, and an assembled thermoelectric device. The Prussian blue-graphite electrode sheet comprises a graphite sheet and a Prussian blue deposition layer on the surface of the graphite sheet. The thermoelectric device comprises a first electrode layer, an ion-thermoelectric hydrogel layer, and a second electrode layer sequentially arranged, both of which are the Prussian blue-graphite electrode sheet of this invention. The Prussian blue-graphite electrode sheet of this invention can store energy and possesses a certain degree of flexibility. The thermoelectric device assembled with this electrode sheet and ion-thermoelectric hydrogel material has advantages such as thermal / electric charging capability, high thermoelectric conversion efficiency, large storage capacity, good flexibility, simple preparation process, low cost, safety, and environmental friendliness, making it suitable for large-scale production applications.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric conversion technology, specifically to a Prussian blue-graphite electrode sheet, its preparation method, and an assembled thermoelectric device. Background Technology

[0002] With the rise of the "Internet of Things" concept, self-powered electronic devices (such as wearable electronic devices, portable detection systems, and soft robots) have attracted considerable attention. Theoretically, it is possible to convert ubiquitous waste heat (such as sunlight, geothermal energy, and waste heat generated by mechanical work or the human body) into electrical energy through energy harvesting devices, which is also one of the effective strategies for solving the global energy crisis and environmental problems.

[0003] The human body can maintain a temperature of around 35°C, while the temperature difference between the human body and the environment typically exceeds 10°C. This large temperature difference provides a significant impetus for energy utilization, making the waste heat generated by the human body a promising application. Thermoelectric devices can convert and store this waste heat, but existing thermoelectric devices generally suffer from high cost, poor mechanical flexibility, poor toughness, high toxicity, low thermo-electric conversion efficiency, and small storage capacity, making it difficult to fully meet practical application requirements.

[0004] Therefore, it is of great significance to develop a thermoelectric device with high thermoelectric conversion efficiency, large storage capacity, low cost, good flexibility, and safety and environmental protection. Summary of the Invention

[0005] The purpose of this invention is to provide a Prussian blue-graphite electrode sheet, its preparation method, and an assembled thermoelectric device.

[0006] The technical solution adopted in this invention is:

[0007] A Prussian blue-graphite electrode sheet, comprising a graphite sheet and a Prussian blue deposition layer deposited on the surface of the graphite sheet.

[0008] A method for preparing a Prussian blue-graphite electrode sheet as described above includes the following steps: assembling a three-electrode system with a graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and a calomel electrode as the reference electrode; preparing an electrodeposition solution by adding ferric chloride, potassium ferricyanide, potassium chloride, and hydrochloric acid to water; and then immersing the three-electrode system in the electrodeposition solution to perform electrodeposition on the surface of the graphite sheet by cyclic voltammetry to form a Prussian blue deposition layer, thereby obtaining the Prussian blue-graphite electrode sheet.

[0009] Preferably, the molar ratio of ferric chloride, potassium ferricyanide, and potassium chloride is 1:1 to 1.5:25 to 30.

[0010] Preferably, the electrodeposition potential range is 0.4V to 0.8V, the scan rate is 40mV / s to 80mV / s, and the number of scans is 10 to 60.

[0011] A thermoelectric device comprising a first electrode layer, an ion-thermoelectric hydrogel layer, and a second electrode layer disposed sequentially; the first electrode layer and the second electrode layer are both the aforementioned Prussian blue-graphite electrode sheets.

[0012] Preferably, the ion-thermoelectric hydrogel in the ion-thermoelectric hydrogel layer is prepared by a method comprising the following steps:

[0013] 1) Acrylamide, potassium acrylate, crosslinking agent and photoinitiator are dispersed in water, and then ultraviolet light-initiated polymerization is carried out to obtain hydrogel;

[0014] 2) The hydrogel is immersed in sulfuric acid solution for dialysis to obtain ion thermoelectric hydrogel.

[0015] Preferably, the mass ratio of acrylamide to potassium acrylate in step 1) is 1:1.5 to 1.7.

[0016] Preferably, the crosslinking agent in step 1) is at least one of N,N-methylenebisacrylamide, divinylbenzene, and diisocyanate.

[0017] Preferably, the photoinitiator in step 1) is at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0018] Preferably, the concentration of the sulfuric acid solution in step 2) is 0.1 mol / L to 1.0 mol / L.

[0019] Preferably, the dialysis time in step 2) is 48h to 96h, and the sulfuric acid solution is replaced every 20h to 30h.

[0020] The principle of this invention: When there is a temperature difference between the two ends of the ion-thermoelectric hydrogel layer in the thermoelectric device of this invention, hydrogen ions and sulfate ions migrate from the hot end to the cold end due to the thermal diffusion effect. However, in the polymer network structure with high cross-linking density, since hydrogen ions are smaller than sulfate ions, the migration resistance of hydrogen ions in the polymer network is smaller than that of sulfate ions, and the migration rate of hydrogen ions is also faster. This causes hydrogen ions to accumulate more quickly at the cold end of the electrode, while sulfate ions remain on the hot side, generating an electric field from the cold electrode to the thermoelectric electrode, thereby generating a thermal diffusion voltage. In addition, when the two ends of the thermoelectric device are electrically connected... When the electrode is capable of oxidation-reduction, in addition to the aforementioned thermal diffusion effect, there is also a thermocouple effect caused by the oxidation-reduction reaction. At the hot end electrode, the thermal diffusion effect makes the hot end electrode more conducive to the occurrence of oxidation reaction, allowing electrons to enter the hot end electrode and giving it a lower voltage, generating a thermoelectric potential consistent with the thermal diffusion effect. At the cold end, thermodynamically, the reduction reaction is favorable, and electrons migrate out of the cold end electrode, thus giving it a higher voltage. Ultimately, the synergistic effect of the thermal diffusion effect and the thermocouple results in the thermoelectric device having a higher output voltage and power.

[0021] The beneficial effects of the present invention are: the Prussian blue-graphite electrode sheet of the present invention can store energy and has a certain degree of flexibility. The thermoelectric device assembled with the ion thermoelectric hydrogel material has the advantages of being heat / electrically rechargeable, having high thermoelectric conversion efficiency, large storage capacity, good flexibility, simple preparation process, low cost, safety and environmental protection, and is suitable for large-scale production and application. Attached Figure Description

[0022] Figure 1 This is an appearance diagram of the graphite sheet and Prussian blue-graphite electrode sheet in Example 1.

[0023] Figure 2 This is a schematic diagram of the thermoelectric device of the present invention.

[0024] Explanation of reference numerals in the attached figures: 10, first electrode layer; 20, ion thermoelectric hydrogel layer; 30, second electrode layer.

[0025] Figure 3 The CV curves are for the thermoelectric devices of Example 1 and the comparative example.

[0026] Figure 4 The diagram shows the open-circuit voltage of the thermoelectric devices in Example 1 and the comparative example under a temperature difference of 20°C.

[0027] Figure 5 The output power diagrams for the thermoelectric devices of Example 1 and the comparative example are shown at a temperature difference of 20°C.

[0028] Figure 6The charge-discharge curves of the thermoelectric devices in Example 1 and the comparative example are shown. Detailed Implementation

[0029] The present invention will be further explained and described below with reference to specific embodiments.

[0030] Example 1:

[0031] A Prussian blue-graphite electrode sheet, the preparation method of which includes the following steps:

[0032] 1) Assemble a three-electrode system using graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and calomel electrode as the reference electrode;

[0033] 2) Add 0.216g of ferric chloride hexahydrate, 0.263g of potassium ferricyanide, 1.49g of potassium chloride and 1.8mL of 38% hydrochloric acid to 200mL of deionized water and stir well to obtain the electrodeposition solution.

[0034] 3) Place the three-electrode system into the electrodeposition solution, and use an electrochemical workstation to perform cyclic voltammetry on the electrodeposition system at a scanning rate of 50 mV / s for 20 cycles within a potential range of 0.4 V to 0.8 V. Then, remove the graphite sheet, rinse it slowly with deionized water, and dry it to obtain the Prussian blue-graphite electrode sheet.

[0035] The appearance of the graphite sheet and Prussian blue-graphite electrode sheet in this embodiment is shown in the figure below. Figure 1 (a is a graphite sheet, b is a Prussian blue-graphite electrode sheet) as shown.

[0036] By Figure 1 It can be seen that a Prussian blue deposition layer did indeed form on the surface of the graphite sheet.

[0037] A thermoelectric device (structural schematic diagram as shown) Figure 2 As shown in the figure, it comprises a first electrode layer, an ion thermoelectric hydrogel layer and a second electrode layer arranged sequentially, wherein the first electrode layer and the second electrode layer are both Prussian blue-graphite electrode sheets in this embodiment.

[0038] The above-mentioned thermoelectric device fabrication method includes the following steps:

[0039] 1) Disperse 3.75g of acrylamide, 6.25g of potassium acrylate, 0.5mL of N,N-methylenebisacrylamide, and 0.1g of 2-hydroxy-2-methylphenylacetone in 18g of deionized water, then pour the mixture into a cylindrical mold and heat it using a wavelength of 365nm and a power of 80mW / cm². 2 Irradiation with ultraviolet light for 6 minutes yielded a hydrogel (cylindrical).

[0040] 2) Immerse the hydrogel in a 0.5 mol / L sulfuric acid solution and dialyze for 72 hours, changing the sulfuric acid solution every 24 hours to obtain an ion thermoelectric hydrogel (cylindrical).

[0041] 3) Attach two Prussian blue-graphite electrode sheets to the two cylindrical surfaces of the ion thermoelectric hydrogel to obtain the thermoelectric device.

[0042] Example 2:

[0043] A Prussian blue-graphite electrode sheet, the preparation method of which includes the following steps:

[0044] 1) Assemble a three-electrode system using graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and calomel electrode as the reference electrode;

[0045] 2) Add 0.216g of ferric chloride hexahydrate, 0.263g of potassium ferricyanide, 1.49g of potassium chloride and 1.8mL of 38% hydrochloric acid to 200mL of deionized water and stir well to obtain the electrodeposition solution.

[0046] 3) Place the three-electrode system into the electrodeposition solution, and use an electrochemical workstation to perform cyclic voltammetry on the electrodeposition system at a scanning rate of 40 mV / s for 20 cycles within a potential range of 0.4 V to 0.8 V. Then, remove the graphite sheet, rinse it slowly with deionized water, and dry it to obtain the Prussian blue-graphite electrode sheet.

[0047] A thermoelectric device is identical to that of Example 1, except that the first and second electrode layers are replaced with Prussian blue-graphite electrode sheets as described in this embodiment.

[0048] Example 3:

[0049] A Prussian blue-graphite electrode sheet, the preparation method of which includes the following steps:

[0050] 1) Assemble a three-electrode system using graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and calomel electrode as the reference electrode;

[0051] 2) Add 0.216g of ferric chloride hexahydrate, 0.263g of potassium ferricyanide, 1.49g of potassium chloride and 1.8mL of 38% hydrochloric acid to 200mL of deionized water and stir well to obtain the electrodeposition solution.

[0052] 3) Place the three-electrode system into the electrodeposition solution, and use an electrochemical workstation to perform cyclic voltammetry on the electrodeposition system at a scanning rate of 60mV / s for 20 cycles within a potential range of 0.4V to 0.8V. Then, remove the graphite sheet, rinse it slowly with deionized water, and dry it to obtain the Prussian blue-graphite electrode sheet.

[0053] A thermoelectric device is identical to that of Example 1, except that the first and second electrode layers are replaced with Prussian blue-graphite electrode sheets as described in this embodiment.

[0054] Example 4:

[0055] A Prussian blue-graphite electrode sheet, the preparation method of which includes the following steps:

[0056] 1) Assemble a three-electrode system using graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and calomel electrode as the reference electrode;

[0057] 2) Add 0.216g of ferric chloride hexahydrate, 0.263g of potassium ferricyanide, 1.49g of potassium chloride and 1.8mL of 38% hydrochloric acid to 200mL of deionized water and stir well to obtain the electrodeposition solution.

[0058] 3) Place the three-electrode system into the electrodeposition solution, and use an electrochemical workstation to perform cyclic voltammetry on the electrodeposition system at a scanning rate of 70 mV / s for 20 cycles within a potential range of 0.4 V to 0.8 V. Then, remove the graphite sheet, rinse it slowly with deionized water, and dry it to obtain the Prussian blue-graphite electrode sheet.

[0059] A thermoelectric device is identical to that of Example 1, except that the first and second electrode layers are replaced with Prussian blue-graphite electrode sheets as described in this embodiment.

[0060] Comparative example:

[0061] A thermoelectric device is identical to Example 1 except that the first electrode layer and the second electrode layer are both replaced with graphite sheets (same as Example 1).

[0062] Performance testing:

[0063] 1) Cyclic voltammetry scans were performed on the thermoelectric devices of Example 1 and the comparative example using an electrochemical workstation. The obtained cyclic voltammetry scan curves (CV curves) are shown below. Figure 3 As shown.

[0064] By Figure 3 It can be seen that the Prussian blue redox peak can be clearly observed in the CV curve of the thermoelectric device in Example 1, and the specific capacitance of the Prussian blue-graphite electrode sheet is 801.69 F·m. -2 ) is much higher than that of graphite sheets (405.73 F·m) -2 This indicates that the deposition of Prussian blue on the graphite sheet significantly increases the specific capacitance of the graphite sheet.

[0065] 2) A temperature difference of 20°C was applied to both ends of the ion-thermoelectric hydrogel layer in the thermoelectric devices of Example 1 and the comparative example using a differential thermometer (cold end set to 10°C, hot end set to 30°C). The open-circuit voltage and output power of the thermoelectric devices were then measured. The resulting open-circuit voltage and output power diagrams of the thermoelectric devices under the 20°C temperature difference are shown below. Figure 4 and Figure 5 As shown.

[0066] Depend on Figure 4 and Figure 5 It can be seen that the deposition of Prussian blue on the graphite sheet greatly increases the specific surface area and specific capacitance of the graphite sheet, which ultimately makes the output voltage and output power of the thermoelectric device in Example 1 much higher.

[0067] 3) The charge-discharge performance of the thermoelectric devices in Example 1 and the comparative example was tested using an electrochemical workstation. The obtained charge-discharge curves are shown below. Figure 6 As shown.

[0068] Depend on Figure 6 It can be seen that the thermoelectric device in Example 1 has a much longer discharge time compared to the thermoelectric device in the comparative example, indicating that the specific capacitance of the Prussian blue-graphite electrode sheet is much higher than that of the graphite sheet.

[0069] Furthermore, tests showed that the specific capacitance of the Prussian blue-graphite electrode sheets in Examples 2-4 was 786.34 F·m, respectively. -2 740.71 F·m -2 and 678.88 F·m -2 .

[0070] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A thermoelectric device, characterized in that, It consists of a first electrode layer, an ion-thermoelectric hydrogel layer, and a second electrode layer arranged sequentially; both the first and second electrode layers are Prussian blue-graphite electrode sheets; the Prussian blue-graphite electrode sheet consists of a graphite sheet and a Prussian blue deposition layer deposited on the surface of the graphite sheet; the ion-thermoelectric hydrogel in the ion-thermoelectric hydrogel layer is prepared by a method including the following steps: 1) dispersing acrylamide, potassium acrylate, crosslinking agent, and photoinitiator in water, and then performing ultraviolet light-initiated polymerization to obtain a hydrogel; 2) immersing the hydrogel in a sulfuric acid solution for dialyzing to obtain the ion-thermoelectric hydrogel.

2. The thermoelectric device according to claim 1, characterized in that: The Prussian blue-graphite electrode sheet is prepared by a method including the following steps: assembling a three-electrode system with a graphite sheet as the working electrode, carbon cloth as the auxiliary electrode, and a calomel electrode as the reference electrode; preparing an electrodeposition solution by adding ferric chloride, potassium ferricyanide, potassium chloride, and hydrochloric acid to water; and then immersing the three-electrode system in the electrodeposition solution to perform electrodeposition on the surface of the graphite sheet by cyclic voltammetry to form a Prussian blue deposition layer, thus obtaining the Prussian blue-graphite electrode sheet.

3. The thermoelectric device according to claim 2, characterized in that: The electrodeposition potential range is 0.4V to 0.8V, the scan rate is 40mV / s to 80mV / s, and the number of scans is 10 to 60.

4. The thermoelectric device according to claim 1, characterized in that: In step 1), the mass ratio of acrylamide to potassium acrylate is 1:1.5 to 1.

7.

5. The thermoelectric device according to claim 1 or 4, characterized in that: Step 1) The crosslinking agent is at least one of N,N-methylenebisacrylamide, divinylbenzene, and diisocyanate.

6. The thermoelectric device according to claim 1 or 4, characterized in that: Step 1) The photoinitiator is at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

7. The thermoelectric device according to claim 1, characterized in that: Step 2) The concentration of the sulfuric acid solution is 0.1 mol / L to 1.0 mol / L.

8. The thermoelectric device according to claim 1 or 7, characterized in that: Step 2) The dialysis time is 48h to 96h, and the sulfuric acid solution is changed every 20h to 30h.

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