Ion thermoelectric gel battery and preparation method and application thereof

Abstract

The invention discloses an ion thermoelectric gel battery as well as a preparation method and application thereof. The ion thermoelectric gel battery comprises a metal electrode, ion gel and a carbon electrode which are arranged in sequence, the ionic gel comprises the following components: a gel matrix and an oxidation / reduction couple. According to the ion thermoelectric gel battery, the organic matrix is used as the gel matrix, the oxidation / reduction couple is added, and the concentration and proportion of the oxidation / reduction couple are adjusted, so that the thermoelectric chemical effect can be improved, and high ion thermoelectric potential and high output power density can be obtained. The metal carbon asymmetric electrodes are used, the in-situ micro primary battery effect and the coupling enhanced thermoelectric chemical effect are introduced, the output voltage, the current density and the output power density of the ionic thermal battery are improved, the output power density can reach 1.6 W m <-2 > under the temperature difference of 4K, and the ionic thermal battery has good thermoelectric conversion performance.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoelectric materials, and in particular relates to an ion thermoelectric gel battery and a preparation method and application thereof. Background Art

[0002] With the rapid development of wireless sensor technology, hundreds of millions of distributed sensors have been deployed in vast spaces. These sensors rely heavily on regularly charged batteries or wired power grids to collect signals and transmit them to terminal networks, greatly increasing the maintenance cost and complexity of information collection and transmission. Thermoelectric conversion technology can capture thermal energy from the surrounding environment and realize direct conversion of thermal energy to electrical energy. It has the advantages of simple structure, environmental friendliness, and no noise, and can meet the self-powered needs of sensors.

[0003] Compared with traditional semiconductor electronic thermoelectric materials with electrons as carriers, ionic thermoelectric gels with ions as carriers have the advantages of high ionic thermoelectric potential (mV / K level), excellent flexibility, simple preparation and integration, low cost, etc. They have unique advantages in near-room temperature power generation and are receiving more and more attention. In recent years, after rapid research and development, ionic thermoelectric gels have a high thermoelectric potential of >40mV / K, and after device integration, they can meet the voltage requirements of sensors under small temperature differences, but the low output power density still seriously restricts their market application. Therefore, it is particularly important to improve the output power density of ionic thermoelectric gels at the current stage. Summary of the invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide an ionic thermoelectric gel battery. The second purpose of the present invention is to provide a method for preparing the above-mentioned ionic thermoelectric gel battery. The third purpose of the present invention is to provide an application of the above-mentioned ionic thermoelectric gel battery. The fourth purpose of the present invention is to provide a temperature difference power generation device. The fifth purpose of the present invention is to provide a wearable device. In order to achieve the above-mentioned purposes, the technical solutions adopted by the present invention are:

[0005] The first aspect of the present invention provides an ion thermoelectric gel battery, comprising a metal electrode, an ion gel and a carbon electrode arranged in sequence; the components of the ion gel include a gel matrix and an oxidation / reduction electrode pair.

[0006] Preferably, the oxidation / reduction couple is selected from K3Fe(CN)6 / K4Fe(CN)6 or Na2SO4 / Na2SO3.

[0007] More preferably, K3Fe(CN)6 is used as the oxidation electrode and K4Fe(CN)6 is used as the reduction electrode in the oxidation / reduction electrode, and the molar ratio of K3Fe(CN)6 to K4Fe(CN)6 is 1:(1 to 5).

[0008] Preferably, the gelling matrix is ​​selected from at least one of gelatin, polyvinyl alcohol, polyacrylamide and chitosan.

[0009] Preferably, the mass molar ratio of the gel matrix to the oxidation / reduction electrode is 1 g: (0.04-0.1) mmol.

[0010] Preferably, the metal electrode includes at least one of copper foil, iron foil and zinc foil.

[0011] More preferably, the metal electrode is a copper foil with a thickness of 5-20 μm.

[0012] Further preferably, the copper foil is selected from a smooth copper foil or a rough copper foil.

[0013] Further preferably, the surface of the copper foil is gold-plated.

[0014] More preferably, the surface of the metal electrode is treated with a gold layer by ion sputtering, and the sputtering time is 30-150s. More preferably, the gold layer on the surface of the metal electrode is sputtered for 60-120s.

[0015] Preferably, the carbon electrode comprises at least one of graphite paper, carbon fiber cloth, graphite felt and graphene.

[0016] Preferably, the operating temperature range of the ionic thermoelectric gel battery material is 16-36°C.

[0017] The second aspect of the present invention provides a method for preparing the ionic thermoelectric gel battery of the first aspect, comprising the following steps: arranging a metal electrode and a carbon electrode on both sides of the ionic gel, respectively, to prepare the ionic thermoelectric gel battery.

[0018] Preferably, the method for preparing the ion gel comprises the following steps: mixing a gel matrix, an oxidation / reduction electrode pair and a solvent to obtain the ion gel.

[0019] More preferably, the solvent is selected from one of water, methanol and propanol.

[0020] More preferably, the mixing is performed at 25-100°C.

[0021] More preferably, the mixing is performed at 60-70°C.

[0022] More preferably, the mixing is performed under stirring.

[0023] More preferably, the stirring speed is 300 to 1000 rpm; and the stirring time is 5 to 20 min.

[0024] More preferably, the ratio of the gel matrix to the solvent is 1 g:(2-5) mL.

[0025] The third aspect of the present invention provides the use of the ionic thermoelectric gel battery described in the first aspect in temperature difference power generation.

[0026] Preferably, in the temperature difference power generation of the ionic thermoelectric gel battery, the metal electrode is close to the hot end, and the carbon electrode is close to the cold end.

[0027] The inventive concept of the present invention: The coupled ion gel thermal battery of the present invention uses an organic matrix with added oxidation / reduction electrodes as a gel matrix, and introduces the energy of the micro-galvanic cell effect in situ by using metal foil and carbon material as electrodes, which is beneficial to improving the output voltage and current density of the gel thermal battery to obtain a high output power density.

[0028] After the thermoelectric gel and asymmetric electrodes form a thermobattery, the oxidation / reduction pair utilizes the thermoelectrochemical effect to cause an oxidation reaction at the hot end of the thermobattery, releasing electrons that gather on the hot end electrode (metal foil), and the electrons return to the cold end (carbon material) of the thermobattery through an external circuit; the cold end electrode receives electrons and causes a reduction reaction; the oxidation products and reduction products return to the counter electrode under the action of diffusion. At the same time, the metal / metal cation undergoes a microgalvanic reaction, losing electrons at the hot end electrode to cause an oxidation reaction, and the released electrons return to the cold end through an external circuit; the metal cation diffuses in the gel to the cold end electrode, receives electrons, and causes a reduction reaction.

[0029] Specifically, after the thermoelectric gel and the asymmetric electrode form a thermoelectric battery, the oxidation / reduction electrode Fe(CN)6 4- and Fe(CN)6 3- Using the thermoelectrochemical effect, an oxidation reaction occurs at the hot end electrode (metal foil) of the thermobattery to generate Fe(CN)6 4- -e→Fe(CN)6 3- , releasing electrons to gather on the hot end electrode, and the electrons return to the cold end electrode (carbon material) of the thermal battery through the external circuit; the cold end electrode receives electrons and a reduction reaction occurs Fe(CN)6 3- +e→Fe(CN)6 4- ; The oxidation products and reduction products return to the counter electrode under diffusion. At the same time, the metal / metal cation (M / M n+ ) undergoes a micro-galvanic cell reaction, and an oxidation reaction M–ne→M occurs at the hot end electrode n+ The released electrons return to the cold end through the external circuit; the metal cations diffuse in the gel to the cold end electrode, receiving the electrons to undergo a reduction reaction M n++ne→M. The introduced micro-galvanic battery effect is coupled with the thermo-electrochemical effect, which enhances the output voltage, current density and output power density of the thermal battery. The introduced micro-galvanic battery effect is coupled with the thermo-electrochemical effect, which enhances the output voltage, current density and output power density of the thermal battery.

[0030] A fourth aspect of the present invention provides a temperature difference power generation device, comprising the ionic thermoelectric gel battery of the first aspect.

[0031] Preferably, the number of the ionic thermoelectric gel batteries in the temperature difference power generation device is one or more.

[0032] More preferably, when there are multiple ionic thermoelectric gel batteries, the ionic thermoelectric gel batteries are sequentially connected in series.

[0033] Further preferably, the ionic thermoelectric gel batteries are connected in series via copper conductive glue.

[0034] A fifth aspect of the present invention provides a wearable device, which includes the temperature difference power generation device described in the fourth aspect.

[0035] The beneficial effects of the present invention are:

[0036] (1) The present invention provides an ionic thermoelectric gel battery, comprising a metal electrode, an ionic gel and a carbon electrode stacked in sequence; the components of the ionic gel include a gel matrix and an oxidation / reduction electrode pair. The ionic thermoelectric gel battery of the present invention uses an organic matrix as a gel matrix, and by adding an oxidation / reduction electrode pair and adjusting the concentration and ratio of the oxidation / reduction electrode pair, it is beneficial to improve the thermoelectrochemical effect to obtain a high ionic thermoelectric potential and output power density. The present invention uses a metal||carbon asymmetric electrode, introduces an in-situ micro-galvanic cell effect, and couples the enhanced thermoelectrochemical effect to improve the output voltage, current density and output power density of the ionic thermoelectric battery. The output power density can reach 1.6W m at a temperature difference of 4°C. -2 , making it have good thermoelectric conversion performance.

[0037] (2) The present invention uses gel as the battery electrolyte matrix and uses flexible metal||carbon electrodes, so that the prepared ion thermal battery has excellent flexibility and is suitable for preparing a flexible temperature difference power generation device. The temperature difference power generation device provided by the present invention uses low-grade waste heat to output high voltage and high output power density, and can obtain an open circuit voltage of up to 1.4V and a power density of 0.22W m -2 The peak power density of the thermoelectric power generation device is small in size, high in output voltage, high in power, and high in energy conversion efficiency. It can also be further made into wearable equipment with good flexibility and ductility. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the working mechanism of the micro-galvanic cell effect-enhanced ion gel thermal battery of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure of the coupled ion thermal battery of the present invention;

[0040] Figure 3 A bar graph showing the relationship between the peak power density and potassium ferrocyanide concentration of the coupled ion thermal battery of Examples 1-5;

[0041] Figure 4 It is a peak power density-temperature dotted line graph of the coupled ion thermal battery of Example 3;

[0042] Figure 5 It is a power density curve diagram of the coupled ion thermal battery of Example 3, Comparative Example 1 and Comparative Example 2;

[0043] Figure 6 Output voltage and power density curve of the thermoelectric power generation device;

[0044] Figure 7 This is a physical picture of a wearable thermoelectric power generation device that uses body temperature to generate electricity. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below through specific examples. The raw materials used in the following examples, unless otherwise specified, can be obtained from conventional commercial sources or prepared and separated by simple synthesis; the processes used, unless otherwise specified, are conventional processes in the art.

[0046] The schematic diagram of the working mechanism of the micro-galvanic cell effect enhanced coupled ion thermal battery of the present invention is as follows Figure 1 As shown in the figure, the specific working mechanism is as follows: when the thermoelectric gel and asymmetric electrodes form an ion thermal battery, the oxidation / reduction pair Fe(CN)6 4- and Fe(CN)6 3- Using the thermoelectrochemical effect, an oxidation reaction Fe(CN)6 occurs at the hot end of the ion thermal battery. 4- -e→Fe(CN)6 3- , releasing electrons to gather on the hot end electrode, and the electrons return to the cold end of the ion thermal battery through the external circuit; the cold end electrode receives electrons and a reduction reaction occurs Fe(CN)6 3- +e→Fe(CN)6 4- ; The oxidation products and reduction products return to the counter electrode under diffusion. At the same time, the metal / metal cation (M / M n+ ) undergoes a micro-galvanic cell reaction, and an oxidation reaction M–ne→M occurs at the hot end electrode n+ The released electrons return to the cold end through the external circuit; the metal cations diffuse in the gel to the cold end electrode, receiving the electrons to undergo a reduction reaction Mn+ +ne→M. The introduced microgalvanic effect is coupled with the thermoelectrochemical effect to enhance the output voltage, current density and output power density of the thermal battery.

[0047] Example 1

[0048] This embodiment provides an ionic thermoelectric gel battery, and the preparation method thereof is as follows:

[0049] (1) Weigh 3 g of gelatin (final concentration: 0.38 g / mL), 0.0783 g of potassium ferrocyanide (final concentration: 0.03 mol / L), and 0.4393 g of potassium ferrocyanide (final concentration: 0.13 mol / L) and add to 8 mL of water to obtain a mixture;

[0050] (2) mechanically stirring the mixture obtained in step (1) at a temperature of 70° C. and a stirring speed of 300 rpm for 5 minutes to melt the gelatin and mix it evenly; then mechanically stirring it at a stirring speed of 800 rpm for 5 minutes to promote cross-linking and reorganization of the gelatin molecular chains, and obtaining an ionic thermoelectric gel after cooling;

[0051] (3) The ionic thermoelectric gel prepared in step (2) is injected into the mold cavity of a 1×1×0.2 cm square mold, and then the upper and lower ends of the mold are covered with smooth copper gold plating (using Hitachi MC1000 ion sputtering instrument, gold target purity is 99.999%, sputtering current is 25 mA, sputtering time is 90 s, and the 90 s in the following embodiments and comparative examples also adopt the above sputtering conditions) and graphite paper electrodes to form a sandwich structure of metal electrode sheet-thermoelectric gel-graphite electrode sheet, and a gel ionic thermal battery is prepared. The structural schematic diagram of the high-temperature ionic thermoelectric conversion device of the present invention is shown in FIG. Figure 2 As shown, A is a metal electrode, B is a graphite electrode, C is a mold, and D is a thermoelectric gel. The ionic thermoelectric gel D is placed in the cavity of the mold C, and a copper-plated gold electrode A and a graphite paper electrode B are respectively arranged above and below.

[0052] When the ion thermoelectric gel battery is used for temperature difference power generation, the copper electrode is at the hot end and the graphite paper electrode is at the cold end. The hot end and the cold end are tightly connected to the copper electrode and the graphite paper electrode respectively. Different temperature differences are achieved by controlling the temperatures of the hot end and the cold end.

[0053] Example 2

[0054] This embodiment provides an ionic thermoelectric gel battery, which is different from Embodiment 1 in that the mixture in step (1) is prepared from the following raw materials: 3 g of gelatin (final concentration 0.38 g / mL), 0.1305 g of potassium ferrocyanide (final concentration 0.05 mol / L) and 0.4393 g of potassium ferrocyanide (final concentration 0.13 mol / L) are weighed and added into 8 mL of water to obtain a mixture; the rest of the preparation method is the same as that in Embodiment 1.

[0055] Example 3

[0056] This embodiment provides an ionic thermoelectric gel battery, which is different from Embodiment 1 in that the mixture in step (1) is prepared from the following raw materials: 3 g of gelatin (final concentration 0.38 g / mL), 0.2088 g of potassium ferrocyanide (final concentration 0.08 mol / L) and 0.4393 g of potassium ferrocyanide (final concentration 0.13 mol / L) are weighed and added into 8 mL of water to obtain a mixture; the rest of the preparation method is the same as that in Embodiment 1.

[0057] Example 4

[0058] This embodiment provides an ionic thermoelectric gel battery, which is different from Embodiment 1 in that the mixture in step (1) is prepared from the following raw materials: 3 g of gelatin (final concentration 0.38 g / mL), 0.2349 g of potassium ferrocyanide (final concentration 0.09 mol / L) and 0.4393 g of potassium ferrocyanide (final concentration 0.13 mol / L) are weighed and added into 8 mL of water to obtain a mixture; the rest of the preparation method is the same as that in Embodiment 1.

[0059] Example 5

[0060] This embodiment provides an ionic thermoelectric gel battery, which is different from Embodiment 1 in that the mixture in step (1) is prepared from the following raw materials: 3 g of gelatin (final concentration 0.38 g / mL), 0.2610 g of potassium ferrocyanide (final concentration 0.10 mol / L) and 0.4393 g of potassium ferrocyanide (final concentration 0.13 mol / L) are weighed and added into 8 mL of water to obtain a mixture; the rest of the preparation method is the same as that in Embodiment 1.

[0061] Comparative Example 1

[0062] This comparative example provides an ionic thermoelectric gel battery, which is different from Example 3 in that step (3) replaces smooth copper gold plating (90s) with rough copper gold plating (90s); the rest of the preparation method is the same as Example 1.

[0063] Comparative Example 2

[0064] This comparative example provides an ionic thermoelectric gel battery, which is different from Example 3 in that step (3) replaces smooth copper with gold plating (90s) with rough copper; the rest of the preparation method is the same as Example 1.

[0065] Battery Characterization

[0066] 1. Test the temperature difference power generation performance of the gel ion thermal batteries prepared in Examples 1-5. The test method is: under the temperature condition of 20°C, a temperature difference of 4°C is applied to the hot end and the cold end, and then the output power of each gel ion thermal battery is tested. The results are as follows: Figure 3 As shown in Figure 2, the amount of potassium ferrocyanide used in the gel ion thermal batteries prepared in Examples 1-5 is different. With the increase of potassium ferrocyanide concentration, the peak power density of the gel ion thermal batteries first increases and then decreases, which are 16, 32, 65, 21, and 14 mW m, respectively. -2 The maximum peak power density of the gel ion thermal battery in Example 3 is 65mW m -2 .

[0067] 2. The temperature difference power generation performance of the gel ion thermal battery prepared in Example 3 was tested. The test method was as follows: under different temperature conditions (16-36°C), a temperature difference of 4°C was applied to the hot end and the cold end, and then the power density of the gel ion thermal battery was tested. The relationship between the peak power density test result and the test temperature is shown in FIG. Figure 4 shown by Figure 4 It can be seen that with the increase of the test temperature, the peak power density of the gel ion thermal battery first increases and then decreases, and the maximum peak power density is obtained at 32°C. At present, most of the research on ion gel thermal batteries is based on room temperature (25°C) and below, and there are few research reports on high temperature areas (25-40°C). In the high temperature area, the atomic / ion thermal motion is intense, and the parameters such as the ion diffusion rate and the ion conductivity of the gel can be improved. The prepared gel ion thermal battery of the present invention can be used in the high temperature area, which is conducive to further improving the ion thermoelectric conversion performance. The development and expansion of the thermoelectric performance in the high temperature area has important research significance and economic value for the recovery and utilization of low-grade waste heat.

[0068] 3. Test the temperature difference power generation performance of the ion thermoelectric gel battery of Example 3 and Comparative Examples 1-2. The test method is: at a temperature condition of 32°C, a temperature difference of 4°C is applied to the hot end and the cold end, and then the power density of the gel ion thermoelectric battery is tested. The peak power density test results are as follows: Figure 5As shown; when the comparative example 1 uses rough copper plated with gold (90s) as the metal electrode and is applied to the prepared gel ion thermal battery, its output power density and current density are better than the gel ion thermal battery prepared by smooth copper plated with gold (90s) in Example 3; when the comparative example 2 uses rough copper as the metal electrode and is applied to the prepared gel ion thermal battery, its output power density and current density are better than the gel ion thermal batteries prepared by Example 3 and comparative example 1, indicating that the gel ion thermal battery prepared by comparative example 2 using rough copper as the metal electrode has the best output power density and current density, and the micro-galvanic battery effect is regulated by increasing the specific surface area of ​​the metal electrode, so that the coupled ion thermal battery can output a larger voltage and power density, and the rough copper metal electrode can significantly improve the thermoelectric performance of the ion gel. However, the ions in the gel have a corrosive effect on the metal electrode, and a large electrode specific surface area will shorten the electrode life of the gel ion thermal battery; by evaporating the gold layer, the gel ions are isolated and buffered, and the output power density and electrode life can be balanced to a certain extent. Therefore, compared with Example 3, the voltage and power density of the ionic thermoelectric gel battery of Comparative Examples 1-2 are greater, but the reliability is reduced.

[0069] 4. Use the ion thermoelectric gel battery prepared in Comparative Example 1 to make a temperature difference power generation device and a wearable device. Place the copper electrodes of the 10 gel ion thermoelectric batteries obtained in Comparative Example 1 on the same side, and the graphite paper electrode on the other side, and use copper tape to connect them in series in the manner of "copper-graphite paper-copper-graphite paper" to make a temperature difference power generation device. Among them, the copper foil electrode of the ion thermoelectric conversion device is at the hot end, and the graphite electrode is at the cold end. The hot end and the cold end are tightly connected to the copper foil electrode and the graphite electrode, respectively. By controlling the temperature of the hot end and the cold end, different temperature differences can be achieved.

[0070] The thermoelectric power generation device was placed at a temperature of 32°C, and a temperature difference of 4°C was applied to the hot end and the cold end to test the voltage, current, and output power density of the power generation device. The voltage-current density curve and power density-current density curve of the thermoelectric power generation device are shown in Figure 1. Figure 6 As shown. Figure 6 It can be seen that the thermoelectric power generation device prepared by the present invention can obtain an open circuit voltage of up to 1.4V and a power of 0.22W m -2 The peak power density is the highest value among the ion gel thermoelectric power generation devices reported so far.

[0071] The prepared thermoelectric power generation device is encapsulated with a polyethylene film, and the positive and negative electrodes are reserved to obtain a wearable device. The copper electrode side of the wearable thermoelectric power generation device is tightly attached to the human skin, and the graphite paper electrode side is exposed to the surrounding environment, and the temperature difference between the skin and the surrounding environment is used to generate electricity. After temperature collection, the ambient temperature is 26°C and the human skin temperature is 29°C, resulting in a temperature difference of ~3°C. Figure 7 As shown, the wearable temperature difference power generation device can generate an open circuit voltage of up to 1.17V and can drive the electronic watch to work normally.

[0072] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An ion thermoelectric gel battery, characterized in that: The invention comprises a metal electrode, an ion gel and a carbon electrode which are arranged in sequence; the components of the ion gel include a gel matrix and an oxidation / reduction electrode pair.

2. The ionic thermoelectric gel battery according to claim 1, characterized in that: The oxidation / reduction electrode pair is selected from K3Fe(CN)6 / K4Fe(CN)6 or Na2SO4 / Na2SO3.

3. The ionic thermoelectric gel battery according to claim 1, characterized in that: The gelling matrix is ​​selected from at least one of gelatin, polyvinyl alcohol, polyacrylamide and chitosan.

4. The ionic thermoelectric gel battery according to claim 1, characterized in that: The metal electrode includes at least one of copper foil, iron foil and zinc foil.

5. The ionic thermoelectric gel battery according to claim 1, characterized in that: The carbon electrode includes at least one of graphite paper, carbon fiber cloth, graphite felt and graphene.

6. The method for preparing the ionic thermoelectric gel battery according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: a metal electrode and a carbon electrode are respectively arranged on two sides of the ion gel to prepare the ion thermoelectric gel battery.

7. The method for preparing an ionic thermoelectric gel battery according to claim 6, characterized in that: The preparation method of the ion gel comprises the following steps: mixing a gel matrix, an oxidation / reduction electrode pair and a solvent to obtain the ion gel.

8. Application of the ionic thermoelectric gel battery according to any one of claims 1 to 5 in temperature difference power generation.

9. A temperature difference power generation device, characterized in that: The invention comprises the ionic thermoelectric gel battery as described in any one of claims 1 to 5.

10. A wearable device, characterized in that: The wearable equipment includes the temperature difference power generation device according to claim 9.

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