CN115116757A - Low temperature resistant and high voltage resistant symmetrical miniature supercapacitor - Google Patents

Abstract

The invention relates to a low-temperature-resistant and high-voltage-resistant symmetrical miniature super capacitor, and belongs to the technical field of super capacitors. The symmetrical micro supercapacitor is formed by constructing a micro interdigital electrode on a substrate material, coating a low-temperature-resistant and high-pressure-resistant polyacrylamide gel electrolyte on the surface of the micro interdigital electrode and then packaging the micro interdigital electrode by a packaging material, wherein the lowest working temperature can reach-40 ℃ and can bear the high voltage of 2.6V. The symmetrical micro super capacitor disclosed by the invention is simple in structure, easy to prepare, low in cost, good in rate performance, excellent in area and volume energy density, excellent in low temperature resistance and high in output voltage, and has a wide application prospect in the field of energy storage devices in wide temperature regions.

Description

A symmetric micro supercapacitor with low temperature resistance and high voltage resistance

technical field

The invention relates to a low-temperature-resistant and high-voltage-resistant symmetric miniature supercapacitor, belonging to the technical field of supercapacitors.

Background technique

The potential applications of flexible electronics in implantable medical devices, smart electronic skins, foldable displays, and conformal human-machine interfaces have driven the rapid development of high-performance miniaturized energy storage devices. Interdigitated micro-supercapacitors exhibit higher power density, better charge/discharge rates, and longer cycle life than interdigitated microbatteries, however, their relatively low energy density greatly hinders Wide range of applications. In principle, the energy density (E) of a given micro supercapacitor is calculated by E = 1/2CV ² , where C and V are the specific capacitance and operating voltage window of the microdevice, respectively. Therefore, the working voltage window plays a crucial role in improving the energy density. Most of the reported micro-supercapacitors are symmetric, and their operating voltages based on aqueous electrolytes are limited to 0.6–1 V. To address this issue, a design to fabricate asymmetric micro-supercapacitors by pairing two different electrodes was proposed to obtain high operating voltages. In practice, these high-voltage asymmetric micro-supercapacitors typically have voltages below 1.8V and very few asymmetrical micro-supercapacitors can reach a maximum operating voltage of 2V. In addition, the fabrication of asymmetric micro-supercapacitors is far more complex and costly than that of symmetric micro-supercapacitors. On the other hand, the temperature range of the micro-supercapacitors that have been reported so far is very narrow, and the electrochemical performance will be seriously attenuated once it encounters a cold climate environment.

SUMMARY OF THE INVENTION

Aiming at the problems of low working voltage, poor temperature resistance and high manufacturing cost of the current micro-supercapacitors, the present invention provides a symmetric micro-supercapacitor with low temperature resistance and high voltage resistance. The symmetric micro-supercapacitor exhibits good rate performance, excellent The area and volume energy density, excellent low temperature resistance and high output voltage have broad application prospects in the field of energy storage devices in a wide temperature range.

The object of the present invention is achieved through the following technical solutions.

A symmetric micro supercapacitor with low temperature resistance and high voltage resistance, comprising micro interdigitated electrodes, low temperature and high pressure resistance polyacrylamide gel electrolyte, base material and packaging material;

The specific assembly relationship is as follows: construct micro interdigitated electrodes on the base material, coat the low temperature and high pressure resistant polyacrylamide gel electrolyte on the surface of the micro interdigitated electrodes, and then encapsulate them with packaging materials to obtain the symmetrical micro interdigitated electrodes. Super capacitor;

The minimum operating temperature of the symmetric micro-supercapacitor can reach -40°C, and it can withstand a high voltage of 2.6V.

Preferably, the number of interdigitated fingers in the micro interdigitated electrode is 4-12, the width of each interdigital finger is 400-800 μm, the length of each interdigital finger is 2.8-6 mm, and the interval between two adjacent interdigital fingers is 400-800 μm. The distance between the two fingers is 50-200 μm, and the thickness of each interdigital finger is 5-100 μm.

Preferably, the material of the micro interdigital electrode is carbon nanotube, graphene or activated carbon, which can be constructed on the base material by laser direct writing or laser etching technology.

Preferably, both the base material and the packaging material are selected from polyimide or polydimethylsiloxane.

Preferably, the low temperature-resistant and high-pressure-resistant polyacrylamide gel electrolyte is obtained by reacting a polymer monomer, a diene-based cross-linking agent and an initiator in water to obtain a cross-linked hydrogel, and then freeze-drying to form a porous cross-linked hydrogel. The hydrogel was finally immersed in a lithium salt aqueous solution containing a glycerol antifreeze for replacement.

The polymer monomer is preferably at least one of acrylic acid, acrylamide and sodium acrylate, and correspondingly the porous cross-linked hydrogel obtained is acrylic acid, acrylamide, sodium acrylate and their complexes. More preferably, when preparing the cross-linked hydrogel, the molar ratio of the polymer monomer to the solvent water is 0.5-1:10.

The diolefin-based crosslinking agent is preferably N,N'-methylenebisacrylamide. More preferably, when preparing the cross-linked hydrogel, the molar ratio of the diolefin-based cross-linking agent to the solvent water is 0.2-0.6:10000.

The initiator is preferably sodium persulfate, ammonium persulfate or potassium persulfate. More preferably, when preparing the cross-linked hydrogel, the molar ratio of the initiator to the solvent water is 2-4:10000.

The lithium salt aqueous solution is preferably an aqueous solution of lithium nitrate, lithium acetate, lithium bistrifluoromethanesulfonimide or lithium trifluoromethanesulfonate. More preferably, the concentration of lithium salt in the lithium salt aqueous solution is not less than 15 mol/L.

Preferably, the reaction temperature for preparing the cross-linked hydrogel is 40-70° C., and the reaction time is 6-72 h.

Preferably, the freeze-drying temperature is -60--40°C, and the freeze-drying time is 48-96 h.

Preferably, in the lithium salt aqueous solution containing glycerin antifreeze, the volume ratio of glycerol to water is 1:5-7:1, more preferably 0.5-2:1.

Preferably, when immersed in a lithium salt aqueous solution containing a glycerin antifreeze for replacement, the replacement temperature is 40-80° C., and the replacement time is not less than 24 hours.

Beneficial effects:

(1) In the low-temperature-resistant and high-voltage-resistant polyacrylamide gel electrolyte used in the symmetric micro-supercapacitor of the present invention, the introduction of glycerol and a relatively high concentration of lithium salt makes the hydrogen bonding effect of the entire system greatly reduced. Improve, most of the water molecules are firmly locked in the frame structure of the hydrogel, thus greatly reducing the free water molecules in the polyacrylamide gel electrolyte, so that the polyacrylamide gel electrolyte has excellent At the same time, the enhancement of the hydrogen bonding of the whole system reduces the freezing point of the gel, effectively preventing the polyacrylamide gel electrolyte from being frozen under low temperature conditions, so that it can be guaranteed even under low temperature conditions. The normal transmission of ions makes it have good low temperature resistance. Therefore, the symmetric micro supercapacitors based on low temperature and high pressure polyacrylamide gel electrolytes assembled with micro interdigitated electrodes, substrate materials and packaging materials have excellent performance. The low temperature resistance and high voltage resistance can achieve a high voltage window of 0 to 2.6V. More importantly, even at minus 40 °C, the symmetric micro supercapacitor can still work normally, and the highest output voltage can also reach 2.6V.

(2) In the symmetric micro supercapacitor of the present invention, advanced carbon materials (such as carbon nanotubes, graphene, activated carbon) with high electrical conductivity and excellent ability to store charges are used to make micro interdigitated electrodes, which is conducive to improving Electrochemical properties (such as rate capability and cycling performance) of symmetric microsupercapacitors.

(3) In the symmetric micro-supercapacitor of the present invention, based on the tiny size of the micro-supercapacitor itself and the capacity and specific capacity to be provided, the structural parameters of the micro-interdigital electrodes are optimized, so that the symmetric micro-supercapacitor exhibits good performance. excellent rate capability, excellent areal and volumetric energy densities.

(4) In the low-temperature-resistant and high-pressure-resistant polyacrylamide gel electrolyte system of the present invention, the polyacrylamide gel system provides a self-supporting water environment for the electrolyte, and the high concentration of lithium salt and glycerol The introduction is the key point that the polyacrylamide gel electrolyte can withstand high temperature and high pressure. In addition, considering that the viscosity of the lithium salt aqueous solution added with glycerol is relatively high, it is difficult to match the polyacrylamide gel by solvent replacement. Therefore, this application proposes two improvements: first, the porous Polyacrylamide gel, its porous structure is beneficial to the entry of glycerol and lithium salt molecules; secondly, by creating a high temperature environment higher than room temperature, the viscosity of the lithium salt solution of glycerol is reduced, so that salt ions and solvent molecules can be It enters the polyacrylamide gel more smoothly, and finally realizes the rapid construction of high temperature and high pressure polyacrylamide gel electrolyte.

(5) In the low-temperature-resistant and high-pressure-resistant polyacrylamide gel electrolyte system of the present invention, the addition amount of glycerin is a key factor affecting the low temperature resistance performance of the polyacrylamide gel electrolyte. Therefore, by optimizing the addition amount of glycerol, Achieve the best low temperature performance of polyacrylamide gel electrolyte.

(6) The symmetric micro-supercapacitor of the present invention is simple in structure, easy to prepare, and low in cost. By optimizing its composition, especially using polyacrylamide gel electrolyte with low temperature resistance and high pressure resistance, it exhibits good rate performance, excellent The area and volume energy density, excellent low temperature resistance and high output voltage have broad application prospects in the field of energy storage devices in a wide temperature range.

Description of drawings

FIG. 1 is a schematic structural diagram of the micro interdigital electrode constructed in Example 1. FIG.

FIG. 2 is a comparison diagram of the cyclic voltammetry curves of the symmetric micro-supercapacitors prepared in Example 1 under different scan rates.

FIG. 3 is a comparison diagram of the charge-discharge curves of the symmetric micro-supercapacitors prepared in Example 1 under different current densities.

FIG. 4 is a comparison diagram of the cyclic voltammetry curves of the symmetric micro-supercapacitor prepared in Example 1 measured at -40° C. and 25° C. with a scan rate of 100 mV/s, respectively.

FIG. 5 is a comparison diagram of the cyclic voltammetry curves of the symmetric micro-supercapacitors prepared in Example 2 measured at -40° C. and 25° C. with a scan rate of 100 mV/s, respectively.

FIG. 6 is a comparison diagram of the cyclic voltammetry curves of the symmetric micro-supercapacitors prepared in Example 3 measured at -40° C. and 25° C. with a scan rate of 100 mV/s, respectively.

FIG. 7 is a bar graph showing the comparison of the capacity retention ratios of the symmetric micro-supercapacitors prepared in Examples 1 to 3 tested at -40° C. respectively.

Detailed ways

The present invention will be further described below with reference to specific embodiments, wherein, the methods are conventional methods unless otherwise specified, and the raw materials can be obtained from open commercial channels unless otherwise specified.

Example 1

(1) Disperse 0.05mol acrylamide and 0.03mmol N,N'-methylenebisacrylamide in 10mL deionized water by ultrasonic, then add 0.03g (0.13mmol) ammonium persulfate under stirring to initiate polymerization, Then, the polymerization reaction mixture system was quickly poured into a plastic container and sealed, and then the polymerization reaction mixture system was continued to react at 60° C. for 72 hours to obtain a cross-linked hydrogel;

(2) freeze-drying the cross-linked hydrogel under vacuum at -60°C for 72 hours to obtain a porous cross-linked hydrogel;

(3) Dissolve 6g lithium bis-trifluoromethanesulfonimide in 1mL of deionized water, then add 1.3mL of glycerol and mix well to prepare a lithium salt aqueous solution containing glycerol; soak the porous cross-linked hydrogel into a solution containing In the lithium salt aqueous solution of glycerol, placed at 45°C for 72h for solvent replacement, a polyacrylamide gel electrolyte with low temperature resistance and high pressure resistance was obtained;

(4) Adhere the carbon nanotube paper on the insulating and heat-resistant polyimide tape, and then directly write a symmetrical interdigital microelectrode with six interdigitated fingers by laser (see Figure 1 for the specific structure). The width of the fork is about 500μm, the distance between two adjacent fork fingers is about 80μm, the length of each fork is 3.4mm, and the thickness of each fork is 10μm. The area is about 0.1cm ² ; then the polyacrylamide gel electrolyte that is resistant to low temperature and high voltage is directly covered on the surface of the interdigital microelectrode, and finally is packaged with polyimide tape, that is, a low temperature resistant and high voltage resistant polyacrylamide gel electrolyte is constructed. Voltage Symmetrical Micro Supercapacitors.

Example 2

On the basis of Example 1, only the amount of glycerol added in step (3) of Example 1 was changed from 1.3mL to 2.3mL, and other steps and conditions were not changed, correspondingly, a symmetrical micro-miniature with low temperature resistance and high voltage resistance was obtained. Super capacitor.

Example 3

On the basis of Example 1, only the amount of glycerol added in step (3) of Example 1 was changed from 1.3 mL to 3.3 mL, and other steps and conditions were not changed, correspondingly, a symmetrical micro-miniature with low temperature resistance and high voltage resistance was obtained. Super capacitor.

Performance characterization:

Cyclic voltammetry curves were tested on the symmetric micro-supercapacitors prepared in Example 1 at different scan rates (the test results are shown in Figure 2), and the symmetric micro-supercapacitors were tested by charge-discharge curves at different current densities. (The test results are shown in Figure 3). The cyclic voltammetry curves obtained at different scan rates in Fig. 2 are all approximately rectangular in the wide electrochemical window of 0 to 2.6 V, and the charge-discharge curves obtained at different current densities in Fig. 3 are also close to an isosceles The triangle shows the excellent capacitance characteristics and good Coulomb efficiency of the symmetric micro-supercapacitor prepared in Example 1. It should be noted that the cyclic voltammetry curve of the symmetric micro-supercapacitor prepared in Example 1 remains approximately rectangular even at a large scan rate of 1000 mV/s, indicating that the symmetric micro-supercapacitor has excellent high voltage resistance capability.

The cyclic voltammetry curves of the symmetric micro-supercapacitors prepared in Examples 1 to 3 at -40°C and 25°C were respectively tested at a scan rate of 100mV/s. According to the calculation of the CV curves in Figures 4-6 (capacity retention = CV integral area at -40°C/CV integral area at 25°C), the symmetric micro-supercapacitors prepared in Examples 1 to 3 are at -40°C. The capacity retention rates correspond to 70%, 50%, and 47%, respectively (as shown in Figure 7), indicating that by adjusting the content of glycerol, the frost resistance of the gel electrolyte can be effectively improved, thereby improving the low temperature resistance of the micro-supercapacitor. performance.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (12)

1. A low-temperature-resistant and high-voltage-resistant symmetric micro-supercapacitor, characterized in that: comprising micro-interdigital electrodes, low-temperature-resistant and high-voltage-resistant polyacrylamide gel electrolytes, base materials and packaging materials; The specific assembly relationship is as follows: construct micro interdigitated electrodes on the base material, coat the low temperature and high pressure resistant polyacrylamide gel electrolyte on the surface of the micro interdigitated electrodes, and then encapsulate them with packaging materials to obtain the symmetrical micro interdigitated electrodes. Super capacitor; The minimum working temperature of the symmetric micro-supercapacitor reaches -40°C, and the maximum working voltage reaches 2.6V. 2 . The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 1 , wherein the number of interdigitated fingers in the micro interdigitated electrode is 4-12, and the width of each interdigital finger is 4-12 . It is 400-800 μm, the length of each fork is 2.8-6 mm, the distance between two adjacent forks is 50-200 μm, and the thickness of each fork is 5-100 μm. 3 . The symmetric micro supercapacitor with low temperature resistance and high voltage resistance according to claim 1 or 2 , wherein the material of the micro interdigital electrodes is carbon nanotubes, graphene or activated carbon. 4 . 4 . The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 1 , wherein the base material and the packaging material are selected from polyimide or polydimethylsiloxane. 5 . . 5. The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 1, 2 or 4, characterized in that: the low temperature and high pressure resistance polyacrylamide gel electrolyte is first passed through a polymer Monomer, diolefin cross-linking agent and initiator react in water to obtain cross-linked hydrogel, then freeze-dried to form porous cross-linked hydrogel, and finally immersed in lithium salt aqueous solution containing glycerol antifreeze for replacement. . 6 . The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 5 , wherein the polymer monomer is at least one of acrylic acid, acrylamide and sodium acrylate; The olefinic crosslinking agent is N,N'-methylenebisacrylamide; the initiator is sodium persulfate, ammonium persulfate or potassium persulfate. 7. a kind of symmetric miniature supercapacitor with low temperature resistance and high voltage resistance according to claim 6, is characterized in that: when preparing cross-linked hydrogel, the mol ratio of macromolecular monomer and solvent water is 0.5～1: 10. The molar ratio of diene-based crosslinking agent to solvent water is 0.2-0.6:10000, and the molar ratio of initiator to solvent water is 2-4:10000. 8 . The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 7 , wherein the reaction temperature for preparing the cross-linked hydrogel is 40-70° C., and the reaction time is 6-72 h. 9 . 9. The symmetrical micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 5, characterized in that: the lithium salt aqueous solution is lithium nitrate, lithium acetate, lithium bistrifluoromethanesulfonimide or trifluoromethanesulfonimide An aqueous solution of lithium fluoromethanesulfonate, wherein the lithium salt concentration in the lithium salt aqueous solution is not less than 15 mol/L. 10. The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 5, characterized in that: in the lithium salt aqueous solution containing glycerin antifreeze agent, the volume ratio of glycerol to water is 1:5～7 :1. 11. The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 10, characterized in that: in the lithium salt aqueous solution containing glycerin antifreeze agent, the volume ratio of glycerol to water is 0.5 to 2:1 . 12 . The symmetric micro-supercapacitor with low temperature resistance and high voltage resistance according to claim 5 , wherein: when immersed in a lithium salt aqueous solution containing glycerin antifreeze for replacement, the replacement temperature is 40-80° C. 13 . , the replacement time is not less than 24h.

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