A liquid thermal battery electrolyte, a preparation method thereof and a thermal liquid battery comprising the electrolyte

Abstract

The application discloses a kind of liquid thermal battery electrolyte and preparation method and thermal liquid battery comprising the electrolyte, it is related to battery technical field, especially it is related to a kind of liquid thermal battery electrolyte, including potassium ferricyanide, potassium ferrocyanide, guanidine hydrochloride and organic matter;The molar concentration of potassium ferricyanide in the electrolyte is 0.65-1.1mol / L;The molar concentration of potassium ferrocyanide in the electrolyte is 0.70-0.95mol / L;The molar concentration of guanidine hydrochloride in the electrolyte is 6-8mol / L;The molar concentration of organic matter in the electrolyte is 0.1-6.5mol / L.The way that the electrolyte increases organic matter increases the entropy change of whole system, can generate higher open-circuit voltage under the same temperature difference, reaches higher thermoelectric conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a liquid thermal battery electrolyte, a method for preparing the same, and a thermal battery containing the electrolyte. Background Technology

[0002] Globally, environmental energy accounts for a significant portion of total energy consumption. Low-temperature thermal energy sources, such as waste heat from factories, ocean thermal energy, and human body surface energy, are abundant, diverse, and have high total energy value, attracting widespread attention in recent years. However, low-temperature thermal energy is difficult to collect due to its low energy content and tendency to dissipate. Liquid thermal batteries, on the other hand, can effectively utilize this energy by using thermoelectric technology to collect it and convert it into electricity.

[0003] Currently, most liquid thermal batteries use a mixture of potassium ferrocyanide and potassium ferrocyanide as electrolytes. The resulting liquid thermal batteries have the following disadvantages: 1) low ionic conductivity; 2) poor mass transfer; 3) fixed electrolyte system, limiting the potential for improving power generation efficiency; 4) too simple other substances in the system, resulting in poor power generation efficiency; 5) limited temperature difference between the heat source and the surrounding environment.

[0004] Therefore, under the condition of a constant temperature difference, it is necessary to develop a liquid thermal battery with high electrochemical thermoelectric potential to improve power generation and thermoelectric conversion efficiency from the perspective of increasing the entropy change of the entire system, and solve the problem of low thermoelectric conversion efficiency of liquid thermal batteries. Summary of the Invention

[0005] To address the aforementioned problems, the first objective of this invention is to provide a liquid thermal battery electrolyte in which the addition of organic matter increases the entropy change of the entire system, thereby generating a higher open-circuit voltage under the same temperature difference and achieving a higher thermoelectric conversion efficiency.

[0006] The second objective of this invention is to provide a method for preparing a liquid thermal battery electrolyte, which has the advantages of simple preparation process and low cost.

[0007] A third objective of this invention is to provide a hydrothermal battery in which, at a temperature difference of 50K, the open-circuit voltage of a single liquid thermal cell can reach up to 106.1mV and the short-circuit current can reach up to 5.3mA.

[0008] To achieve the first objective mentioned above, the present invention provides the following technical solution: a liquid thermal battery electrolyte, comprising potassium ferrocyanide, potassium ferrocyanide, guanidine hydrochloride, and organic matter;

[0009] The molar concentration of potassium ferricyanide in the electrolyte is 0.65-1.1 mol / L;

[0010] The molar concentration of potassium ferrocyanide in the electrolyte is 0.70-0.95 mol / L;

[0011] The molar concentration of guanidine hydrochloride in the electrolyte is 6-8 mol / L;

[0012] The molar concentration of organic matter in the electrolyte is 0.1-6.5 mol / L.

[0013] By adopting the above technical solution, the electrolyte of the liquid thermal battery is made by adding organic matter to potassium ferrocyanide K3Fe(CN)6, potassium ferrocyanide K4Fe(CN)6 and guanidine hydrochloride GdmCl. By adding organic matter, the entropy change of the entire system is increased, thus generating a higher thermoelectric potential. Under the same temperature difference, a higher open-circuit voltage can be generated, thereby achieving a higher thermoelectric conversion efficiency.

[0014] Furthermore, the organic compound is selected from polyols or n,n-dimethylacetamide C4H9NO. When the organic compound is n,n-dimethylacetamide C4H9NO, the molar concentration of the organic compound is 0.1-3 mol / L.

[0015] Furthermore, the polyol is selected from neopentyl glycol (C5H). 12 O2, 1,4-Butanediol (C4H) 10 O2, 1,6-hexanediol (C6H) 14 O2, methylpropanediol (C4H) 10 O2 or dipropylene glycol C6H 14 At least one of O3.

[0016] Furthermore, the polyol is selected from neopentyl glycol (C5H) with a molar concentration of 0.1-6.5 mol / L. 12 O2, 1,4-butanediol (C4H) with a molar concentration of 0.5-4 mol / L 10 O2, 1,6-hexanediol (C6H2O) at a molar concentration of 1-5 mol / L 14 O2, methylpropanediol (C4H4H4) at a molar concentration of 0.5-3 mol / L 10 O2 or dipropylene glycol C6H at a molar concentration of 0.2-2 mol / L 14 At least one of O3.

[0017] To achieve the second objective mentioned above, the present invention provides the following technical solution: a method for preparing a liquid thermal battery electrolyte, comprising mixing potassium ferricyanide, potassium ferrocyanide, guanidine hydrochloride and organic matter to obtain the electrolyte.

[0018] Furthermore, the preparation method specifically includes the following steps:

[0019] (1) Mix potassium ferricyanide and potassium ferrocyanide evenly, then sonicate and oscillate for 5 minutes. After sonication, add guanidine hydrochloride and mix evenly.

[0020] (2) Add organic matter to the mixture obtained in step (1) and sonicate to obtain an electrolyte.

[0021] To achieve the third objective mentioned above, the present invention provides the following technical solution: a hydrothermal battery, comprising a hydrothermal battery frame and an electrolyte.

[0022] Furthermore, the hydrothermal battery frame is prepared by the following method: a metal sheet is encapsulated with a polyethylene terephthalate (PET) cold lamination film, and then a flexible carbon material inner electrode is attached to the PET cold lamination film. The metal sheet, the PET cold lamination film, and the carbon material inner electrode constitute an MPC sandwich structure electrode. The polymethyl methacrylate acrylic tube is sealed with the upper and lower MPC electrodes to build the hydrothermal battery frame.

[0023] Furthermore, the metal sheet is any one of copper, aluminum, or zinc; preferably, the metal sheet is copper.

[0024] Furthermore, the inner electrode of the carbon material is a carbon felt or carbon fiber cloth; preferably, the inner electrode of the carbon material is a carbon felt electrode.

[0025] In summary, the present invention has the following beneficial effects:

[0026] First, the electrolyte provided by this invention improves the thermoelectric conversion efficiency and increases the electrochemical thermoelectric potential of the entire liquid thermal battery by adding different organic substances to the potassium ferrocyanide K3Fe(CN)6 and potassium ferrocyanide K4Fe(CN)6 electrolyte systems.

[0027] Secondly, at a temperature difference of 50K, the open-circuit voltage of a single liquid thermal battery can reach up to 106.1mV, and the short-circuit current can reach up to 5.3mA. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating the preparation process of the liquid thermal battery electrolyte disclosed in this invention.

[0030] Figure 2 This is a flowchart illustrating the fabrication process of the liquid thermal battery disclosed in this invention.

[0031] Figure 3 This is a schematic diagram of the open-circuit voltage of Examples 1-6 and Comparative Example 1 of the liquid thermal battery disclosed in this invention;

[0032] Figure 4 The above are schematic diagrams of the thermoelectric potential of Examples 1-6 and Comparative Example 1 of the liquid thermal battery disclosed in this invention.

[0033] In the diagram: 1. Acrylic square tube; 2. Copper sheet; 3. PET cold lamination film; 4. Carbon felt electrode. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the appendices in the embodiments of the present invention. Figure 1-4 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Examples and comparative examples of liquid thermal battery electrolytes

[0036] Examples of liquid thermal battery electrolytes

[0037] Example 1

[0038] The specific preparation method of liquid thermal battery electrolyte is as follows:

[0039] (1) Mix 1.9g of potassium ferricyanide K3Fe(CN)6 and 2.5g of potassium ferrocyanide K4Fe(CN)6 thoroughly, dissolve in 7.5ml of deionized water, the concentration of potassium ferricyanide is 0.8mol / L, the concentration of potassium ferrocyanide is 0.8mol / L, and the solution is sonicated for 5min.

[0040] Then add 4.3g of guanidine hydrochloride GdmCl to make the concentration 6mol / L, and then shake to dissolve it completely;

[0041] (2) Add organic matter to the mixture obtained in step (1), and then perform ultrasonic oscillation for 5 minutes. Shake the electrolyte thoroughly to obtain an electrolyte, wherein the organic matter is n,n-dimethylacetamide C4H9NO with a concentration of 1.4 mol / L and an addition amount of 1 ml.

[0042] Example 2: The only difference from Example 1 is that, in step (2), the organic compound is neopentyl glycol (C5H). 12 O2, concentration 6.2 mol / L, added amount 4.875 g.

[0043] Example 3: The only difference from Example 1 is that, in step (2), the organic compound is 1,4-butanediol (C4H). 10 O2, concentration 1.5 mol / L, added in 1 ml.

[0044] Example 4: The only difference from Example 1 is that, in step (2), the organic compound is 1,6-hexanediol (C6H). 14 O2, concentration 4.2 mol / L, added amount 3.75 g.

[0045] Example 5: The only difference from Example 1 is that, in step (2), the organic compound is methylpropanediol (C4H). 10 O2, concentration 1.5 mol / L, added in 1 ml.

[0046] Example 6: The only difference from Example 1 is that, in step (2), the organic compound is dipropylene glycol (C6H). 14 O3, concentration 1.0 mol / L, added in 1 ml.

[0047] Comparative example of liquid thermal battery electrolyte

[0048] Comparative Example 1:

[0049] The specific preparation method of liquid thermal battery electrolyte is as follows:

[0050] 1.9 g of potassium ferricyanide K3Fe(CN)6 and 2.5 g of potassium ferrocyanide K4Fe(CN)6 were thoroughly mixed and dissolved in 7.5 ml of deionized water. The concentration of potassium ferricyanide was 0.8 mol / L and the concentration of potassium ferrocyanide was 0.8 mol / L. The solution was ultrasonically vibrated for 5 min.

[0051] Then add 4.3g of guanidine hydrochloride (GdmCl) to make its concentration 6mol / L, and shake to dissolve it completely to obtain the electrolyte.

[0052] Comparative Example 2: The only difference from Example 1 is that in step (2), the organic compound is n,n-dimethylacetamide C4H9NO with a concentration of 0.05 mol / L.

[0053] Comparative Example 3: The only difference from Example 2 is that, in step (2), the organic compound is neopentyl glycol (C5H). 12 O2 concentration is 0.08 mol / L.

[0054] Comparative Example 4: The only difference from Example 2 is that, in step (2), the organic compound is 1,4-butanediol (C4H). 10 O2 concentration is 0.3 mol / L.

[0055] Comparative Example 5: The only difference from Example 2 is that, in step (2), the organic compound is 1,6-hexanediol (C6H). 14 O2 concentration is 0.5 mol / L.

[0056] Comparative Example 6: The only difference from Example 2 is that, in step (2), the organic compound is methylpropanediol (C4H). 10 O2 concentration is 0.3 mol / L.

[0057] Comparative Example 7: The only difference from Example 2 is that, in step (2), the organic compound is dipropylene glycol (C6H). 14 O3, concentration 0.1 mol / L.

[0058] Examples and performance determination of liquid thermal batteries

[0059] The specific preparation method of the liquid thermal battery involved in this application is as follows: a 0.1 mm thick copper sheet is encapsulated with a 0.07 mm thick polyethylene terephthalate (PET) cold lamination film, and then a 2 mm thick carbon felt electrode is attached to the PET cold lamination film. The copper sheet, PET cold lamination film, and carbon felt electrode constitute an MPC sandwich structure electrode. The copper sheet and PET cold lamination film are cut into 30 mm × 30 mm sizes, and the carbon felt electrode is cut into a T-shape for easy sealing. Two small round holes are punched on one side of a 15 mm × 25 mm × 30 mm acrylic square tube with a wall thickness of 2 mm to facilitate subsequent injection of electrolyte. Take two MPC electrodes and glue the ends of the perforated acrylic square tube to the tube opening and the MPC electrodes with environmentally friendly polymer resin adhesive. The carbon felt electrode should face inward so that it can directly contact the electrolyte later. After bonding, let it sit for 24 hours to seal it. Then, reinforce the seal with UV-curing adhesive to prevent leakage. The entire hydrothermal battery frame is now assembled. Then, inject the liquid hydrothermal battery electrolytes prepared in Examples 1-6 and Comparative Examples 1-6 into the hydrothermal battery frame. When injecting, pay attention to injecting in small amounts and multiple times to ensure that the carbon felt electrode is fully immersed in the electrolyte. Avoid air bubbles in the test device later, which may affect the contact between the inner electrode and the electrolyte. Encapsulate the wires on the T-shaped inner electrode carbon felt and encapsulate the exposed electrode surface with UV-curing adhesive to make a liquid hydrothermal battery.

[0060] The method for determining the electrical performance of the liquid thermal battery involved in this application is as follows: The open-circuit voltage (V) and short-circuit current of the liquid thermal battery under a 50K temperature difference (ΔT) are measured using a Keithley 2450 digital source meter, and the thermoelectric potential (Se) is calculated using the following formula:

[0061]

[0062] Table 1. Performance tests of liquid thermal batteries in Examples 1-6 and Comparative Examples 1-7

[0063] Test Project Example 1 Example 2 Example 3 Example 4 Open circuit voltage (mV) 91.6 104.8 97.9 106.1 Short-circuit current (mA) 4.5 1.6 5.3 2.2 <![CDATA[Thermoelectric potential (mV K -1 )]]> 1.79 2.14 1.87 2.11 Test Project Example 5 Example 6 Comparative Example 1 Comparative Example 2 Open circuit voltage (mV) 104.2 100.2 91.6 89.8 Short-circuit current (mA) 5.0 4.3 5.4 4.9 <![CDATA[Thermoelectric potential (mV K -1 )]]> 2.00 1.92 1.72 1.67 Test Project Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Open circuit voltage (mV) 94.3 93.0 91.9 90.1 Short-circuit current (mA) 5.7 5.3 4.9 5.0 <![CDATA[Thermoelectric potential (mV K -1 )]]> 1.66 1.66 1.80 1.65 Test Project Comparative Example 7 Open circuit voltage (mV) 83.6 Short-circuit current (mA) 5.2 <![CDATA[Thermoelectric potential (mV K -1 )]]> 1.62

[0064] Combining Examples 1-6 and Comparative Examples 1-7 of the liquid thermal battery with Table 1, it can be seen that under a temperature difference of 50K, the open-circuit voltage and short-circuit current of a single hydrothermal battery are improved to varying degrees. The highest open-circuit voltage is observed in Example 4, reaching 106.1mV; the highest open-circuit current is observed in Example 3, reaching 5.3mA. The thermoelectric potential is highest in Example 2, reaching 2.14mV K. -1 Under the same temperature difference, the voltage in Examples 1-6 was increased compared to Comparative Example 1, demonstrating that increasing the type of electrolyte can improve thermoelectric conversion efficiency.

[0065] Based on Example 1 and Comparative Examples 1-2 of the liquid thermal battery and Table 1, it can be seen that when n,n-dimethylacetamide is added to the electrolyte, the variety of substances in the electrolyte increases, which increases the entropy change in the electrolyte and thus increases the open circuit voltage and thermoelectric potential. The higher the concentration of n,n-dimethylacetamide added, the higher the open circuit voltage and thermoelectric potential of the resulting liquid thermal battery.

[0066] Combining Examples 1-6 and Comparative Examples 1-7 of the liquid thermal battery with Table 1, it can be seen that adding polyols to the electrolyte can effectively improve the thermoelectric potential of the liquid thermal battery by increasing the entropy change in the electrolyte. The comparison shows that the higher the concentration of added organic matter, the greater the entropy change of the electrolyte, thus increasing the thermoelectric potential of the liquid thermal battery. It can also be seen that different added organic matter has different degrees of influence on the entropy change of the electrolyte and the thermoelectric potential of the liquid thermal battery. The increase in entropy change in the electrolyte and the thermoelectric potential of the liquid thermal battery is more significant when neopentyl glycol or 1,6-hexanediol is added. Under the same temperature difference, since the open-circuit voltage of Examples 1-6 is significantly higher than that of Comparative Example 1, this liquid thermal battery has a higher thermoelectric conversion efficiency.

[0067] In summary, the liquid thermal battery prepared in this application achieves an open-circuit voltage of 106.1 mV, a short-circuit current of 5.3 mA, and a thermoelectric potential of 2.14 mV K₀ for a single hydrothermal cell under a temperature difference of 50 K. -1 .

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid thermal battery electrolyte, characterized in that, It includes potassium ferrocyanide, potassium ferrocyanide, guanidine hydrochloride, and an organic compound, wherein the organic compound is selected from polyols or n,n-dimethylacetamide (C4H9NO), and the polyol is selected from neopentyl glycol (C5H). 12 O2, 1,4-Butanediol (C4H) 10 O2, 1,6-hexanediol (C6H) 14 O2, methylpropanediol (C4H) 10 O2 or dipropylene glycol C6H 14 At least one of O3; The molar concentration of potassium ferricyanide in the electrolyte is 0.65-1.1 mol / L; The molar concentration of potassium ferrocyanide in the electrolyte is 0.70-0.95 mol / L; The molar concentration of guanidine hydrochloride in the electrolyte is 6-8 mol / L; The molar concentration of organic matter in the electrolyte is 1-6.5 mol / L.

2. The method for preparing a liquid thermal battery electrolyte according to claim 1, characterized in that, This involves mixing potassium ferricyanide, potassium ferrocyanide, guanidine hydrochloride, and organic matter.

3. The method for preparing a liquid thermal battery electrolyte according to claim 2, characterized in that, The preparation method specifically includes the following steps: (1) Mix potassium ferricyanide and potassium ferrocyanide evenly, then perform ultrasonic oscillation, and after ultrasonic treatment for 5 minutes, add guanidine hydrochloride and mix evenly. (2) Add organic matter to the mixture obtained in step (1) and sonicate to obtain an electrolyte.

4. A hydrothermal battery, characterized in that, It includes a hydrothermal battery frame and an electrolyte, wherein the electrolyte is the electrolyte according to claim 1 or the electrolyte prepared by the preparation method according to claim 2 or 3.

5. A hydrothermal battery according to claim 4, characterized in that, The hydrothermal battery frame is prepared by the following method: a metal sheet is encapsulated with polyethylene terephthalate (PET) cold lamination film, and a layer of flexible carbon material inner electrode is attached to the PET cold lamination film. The metal sheet, PET cold lamination film, and carbon material inner electrode constitute an MPC sandwich structure electrode. The polymethyl methacrylate acrylic tube is sealed with the upper and lower MPC electrodes to build the hydrothermal battery frame.

6. A hydrothermal battery according to claim 5, characterized in that, The metal sheet can be any one of copper, aluminum, or zinc.

7. A hydrothermal battery according to claim 5, characterized in that, The carbon material internal electrode is a carbon felt or carbon fiber cloth.

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