Intelligent supercapacitor and method of making the same

Abstract

The application discloses an intelligent super capacitor and a preparation method thereof. The intelligent super capacitor comprises a super capacitor element, an electrolyte and a shell. The super capacitor element comprises a pole piece and a fiber diaphragm. The element is impregnated with the electrolyte. The electrolyte comprises a room temperature ionic liquid and a solvent. The shell comprises a see-through window configured to observe the color of the electrolyte through the see-through window. The intelligent super capacitor can display the energy storage state according to the color change of the electrolyte. Compared with the existing intelligent super capacitor, the intelligent super capacitor has obvious advantages in the monomer working voltage, the intuitiveness of the electric quantity observation and the preparation cost.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage devices, and more specifically, to intelligent supercapacitors and their preparation methods. Background Technology

[0002] In the fields of science and technology, enabling devices to operate intelligently and in interactive modes is one of the major current trends. The ability for supercapacitors to operate in intelligent mode is particularly exciting, for example, by providing a clear and intuitive display of the supercapacitor's energy storage status.

[0003] The operating voltage of a single supercapacitor cell based on traditional organic electrolytes is typically below 3V. To further improve the operating voltage of supercapacitor cells, in recent years, many researchers have used solutions containing room-temperature ionic liquids (RTILs) as electrolytes, which can increase the single-cell voltage to above 3V. Because RTIL is a room-temperature molten salt composed of positive and negative ions, it possesses advantages such as being non-toxic, having a near-zero saturated vapor pressure, high conductivity, a wide liquidus temperature range, being non-flammable, having a wide electrochemical window, and being environmentally friendly. Therefore, using RTIL solutions as supercapacitor electrolytes has become one of the most active areas of supercapacitor research.

[0004] In the invention patent with publication number CN103474255A, the inventors prepared a high-voltage electrolyte for supercapacitors by mixing RTIL, nitrile solvents, and high-voltage stabilizers. By applying the prepared high-voltage electrolyte to supercapacitors, they achieved stable cycling of a single supercapacitor cell at 3V. Zhu et al. assembled a high-performance capacitor using room-temperature ionic liquid [Bmim][BF4] / acetonitrile as the electrolyte and high-specific-surface-area graphene oxide (GO) as the electrode active material. Their article was published in Science. According to the cyclic voltammetry and constant-current charge-discharge curves in this article, the operating voltage of the supercapacitor can reach 3.5V, and due to the use of high-specific-surface-area GO, the specific capacitance of a single cell is 160F / g. However, the supercapacitors prepared by these methods do not possess intuitive intelligent features.

[0005] To develop intelligent supercapacitors, CN104867682A provides an electrode for an intelligent supercapacitor. The electrode includes a substrate formed of a transparent conductive material, a patterned layer formed on the substrate, and a background layer formed on the patterned layer. The patterned layer and the background layer are formed of different electrochromic materials. Products assembled using such electrodes can indicate the capacitance and energy storage state of the intelligent supercapacitor, effectively endowing it with intelligence and interactivity, and providing users with the most intuitive visual experience for operating the intelligent supercapacitor. However, because the electrochemical activity range of the electrochromic functional material used in this invention is -0.5 to 0.8V, the operating voltage of the assembled supercapacitor cell is relatively low. Furthermore, the color change process of this invention is quite complex and not easily practical. This is because the electrochromic patterned layer and the background layer of the electrode are arranged opposite each other; when the two electrodes are close to each other and separated by a diaphragm, the color change of the electrodes becomes difficult to observe.

[0006] To improve the reliability of single-color indication, CN111320756A discloses an electroactive polysiloxane, its thin film preparation method, and the application of this thin film in a supercapacitor with dual color and fluorescence indication. By integrating energy storage with electrochromic / electroluminescent functionality, a smart symmetrical supercapacitor device with dual color and fluorescence indication is assembled. The energy state of this device can be simultaneously displayed by color changes from light greenish-yellow to dark green and by the on / off state of a fluorescence switch. However, because the electrochemical activity range of the electrochromic / electroluminescent functional material used in this invention is 0–0.8V, the operating voltage of the assembled supercapacitor cell is relatively low. Furthermore, the electrode material synthesis process used in this invention is complex, requiring a three-electrode battery system, resulting in high manufacturing costs and hindering practical application.

[0007] Chinese patent CN108470630B discloses a composite electrode material for intelligent supercapacitors, its preparation method, and its application. The composite electrode material is prepared by covalently bonding an alkylcarbazole polymer with bromine-containing side chains to acidified hydroxylated carbon nanotubes via a Williamson etherification reaction. Supercapacitors prepared using this composite electrode material exhibit a rapid and reversible color change from dark brown to light gray within the studied potential window. However, the synthesis process of the electrode material used in this invention is complex, the preparation cost is high, and it is difficult to realize practical application. Furthermore, if two electrodes coated with this composite electrode material are used to prepare a symmetrical supercapacitor, the color change of the electrodes is difficult to observe.

[0008] In conclusion, existing smart supercapacitors still need improvement. Summary of the Invention

[0009] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, one objective of this invention is to propose a smart supercapacitor and its fabrication method. This smart supercapacitor can display the energy storage status based on the color change of the electrolyte, and it has significant advantages over existing smart supercapacitors in terms of single-cell operating voltage, intuitiveness of charge observation, and fabrication cost.

[0010] In one aspect of the invention, a smart supercapacitor is provided. According to an embodiment of the invention, the supercapacitor comprises an element, an electrolyte, and a housing; the supercapacitor element includes electrodes and a fiber diaphragm, the supercapacitor element is impregnated with the electrolyte, the electrolyte comprising a room-temperature ionic liquid and a solvent; the housing includes a viewing window configured to observe the color of the electrolyte through the viewing window.

[0011] In this intelligent supercapacitor, a room-temperature ionic liquid solution of a certain concentration is prepared using a room-temperature ionic liquid and a solvent as the electrolyte. Combined with a casing featuring a transparent window, the energy storage status of the supercapacitor can be displayed based on the color change of the electrolyte. Specifically, the color change of the electrolyte is determined by the change in the concentration of the room-temperature ionic liquid. During the charging process, the cations / anions of the room-temperature ionic liquid are adsorbed into the negative / positive electrode active materials of the supercapacitor, causing the electrolyte color to lighten. Once the supercapacitor is fully charged, the electrolyte becomes colorless and transparent. During the discharging process, the cations / anions of the room-temperature ionic liquid return to the electrolyte, causing the electrolyte color to darken. Therefore, the charge of the supercapacitor can be directly determined by observing the electrolyte color. Furthermore, by using a room-temperature ionic liquid solution as the electrolyte, the single-cell operating voltage of the supercapacitor can reach over 3.5V, and it also offers significant advantages in terms of manufacturing cost compared to existing intelligent supercapacitors.

[0012] In some embodiments of the present invention, the room-temperature ionic liquid is at least one of red, orange, yellow, green, blue, indigo, purple, yellowish-red, black, and brown room-temperature ionic liquids, preferably at least one of yellow, yellowish-red, brown, and black room-temperature ionic liquids. By using the above-mentioned dark-colored room-temperature ionic liquids, the significance of electrolyte color changes during the charging and discharging process of the supercapacitor can be further improved, thereby further improving the convenience and accuracy of displaying the energy storage status of the supercapacitor based on the color change of the electrolyte.

[0013] In some embodiments of the present invention, the yellow room-temperature ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium lactate, 1-butyl-3-methylimidazolium tribromide, 1-butyl-3-methylimidazolium thiocyanate, 1-hexyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium chloride; the yellow-red room-temperature ionic liquid is selected from 1-ethyl-3-methylimidazolium diethyl phosphate; the brown room-temperature ionic liquid is selected from at least one of trioctylmethylammonium sulfate and 1-butyl-3-methylimidazolium tetrachloroferrate; and the black room-temperature ionic liquid is selected from 1-butyl-3-methylimidazolium aluminum chloride.

[0014] In some embodiments of the present invention, the solvent is selected from at least one of C1-8 alkyl monohydric alcohols, C1-8 alkyl dihydric alcohols, glycerol, acetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluorobenzene, chlorobenzene, and bromobenzene. These solvents are colorless and transparent, and will not affect the color change of the electrolyte during charging and discharging, thereby ensuring the accuracy of displaying the energy storage status of the supercapacitor based on the color change of the electrolyte. The C1-8 alkyl monohydric alcohols and C1-8 alkyl dihydric alcohols can be straight-chain alcohols or branched-chain alcohols. Specific examples of C1-8 alkyl straight-chain alcohols include methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, etc. Specific examples of C1-8 alkyl branched-chain alcohols include isopropanol, isobutanol, tert-butanol, etc. Specific examples of dihydric alcohols include 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol, etc.

[0015] In some embodiments of the present invention, the concentration of the room-temperature ionic liquid in the electrolyte, by weight percentage, can be 0.5 wt% to 5 wt%, for example, 0.5 wt%, 1 wt%, 1.06 wt%, 1.5 wt%, 1.57 wt%, 1.77 wt%, 2 wt%, 2.06 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, etc., preferably 1 wt% to 3 wt%. In some embodiments of the present invention, the concentration of the room-temperature ionic liquid in the electrolyte, by molar concentration, can be 0.03 mol / L to 0.044 mol / L, for example, 0.03 mol / L, 0.032 mol / L, 0.035 mol / L, 0.038 mol / L, 0.04 mol / L, 0.042 mol / L, 0.044 mol / L, etc. The inventors discovered that if the content of room-temperature ionic liquid in the electrolyte is too low, there will be too much residual electrolyte in the casing after the supercapacitor element is saturated with electrolyte (the residual amount exceeds 20% of the total injected amount), causing the room-temperature ionic liquid to overflow from the casing, thus making the electrolyte insufficient to contribute to the capacity of the supercapacitor; if the content of room-temperature ionic liquid in the electrolyte is too high, there will be no residual electrolyte after the supercapacitor element is saturated with electrolyte, so that the color change of the electrolyte layer on the surface of the element cannot be clearly observed from the viewing window.

[0016] In some embodiments of the present invention, the fiber diaphragm is white and has the property of not changing color over long-term use. Therefore, the color of the fiber diaphragm will not affect the color change of the electrolyte during charging and discharging, thereby ensuring the accuracy of displaying the energy storage status of the supercapacitor based on the color change of the electrolyte. In some embodiments of the present invention, the fiber diaphragm is a Japanese NKK fiber diaphragm.

[0017] In some embodiments of the present invention, the material of the viewing window is selected from at least one of tempered glass, PP board, polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC), styrene-acrylonitrile copolymer, and colorless diamond, with PP board being preferred.

[0018] In some embodiments of the present invention, the light transmittance of the viewing window is above 90%, the pressure resistance range is 8MPa to 18MPa, and it is resistant to electrolyte corrosion, so as to ensure that the viewing window does not leak air and remains clear and transparent after long-term use.

[0019] In some embodiments of the invention, the viewing window is a circular hole of approximately Φ10mm, located near the center of the casing of the smart supercapacitor to facilitate observation of the electrolyte color. Accordingly, other structures or components inside the smart supercapacitor should be positioned away from the viewing window to avoid obstructing it. For example, adhesive tape for bonding the fiber diaphragm can be attached to both ends of the supercapacitor element.

[0020] In some embodiments of the present invention, the single-cell capacitance of the intelligent supercapacitor is 100F to 12000F, and the single-cell rated voltage is 3.6V.

[0021] In some embodiments of the present invention, the intelligent supercapacitor further includes a standard color chart disposed on the outer casing, the standard color chart indicating the color of the electrolyte of the intelligent supercapacitor at different voltages. Specifically, the standard color chart includes the electrolyte colors corresponding to different charge levels of the intelligent supercapacitor. Thus, after observing the electrolyte color through a viewing window, the current charge level of the intelligent supercapacitor can be intuitively understood through the standard color chart.

[0022] In another aspect of the present invention, a method for preparing the intelligent supercapacitor described in the above embodiments is proposed. According to an embodiment of the present invention, the method includes: assembling a supercapacitor element into a casing, injecting an electrolyte, sealing and aging the casing to obtain the intelligent supercapacitor.

[0023] It should be noted that the method of electrolyte injection is not particularly limited. For example, electrolyte can be injected into the supercapacitor casing through any of the following methods: vacuum injection, high-pressure injection, and centrifugal injection.

[0024] In some embodiments of the present invention, the amount of electrolyte injected is 110% to 120% of the saturated electrolyte absorption capacity of the supercapacitor element. Therefore, after the supercapacitor element is saturated, the remaining electrolyte inside the casing accounts for 10% to 20% of the total injected volume, ensuring the convenience and accuracy of displaying the energy storage status of the supercapacitor based on the color change of the electrolyte. The saturated electrolyte absorption capacity of the supercapacitor element can be obtained by vacuum drying the supercapacitor element to saturate it, and then weighing the increase in its mass. Furthermore, the theoretical electrolyte capacity absorbed by the element can be calculated based on the saturated electrolyte absorption capacity.

[0025] In some embodiments of the present invention, the method further includes: creating a standard color chart and placing the standard color chart on the outer casing; the creation of the standard color chart includes: discharging the smart supercapacitor to below 0.05V and obtaining a photograph of the electrolyte in the smart supercapacitor through the viewing window; charging the smart supercapacitor to its rated voltage and, during the charging process, obtaining photographs of the electrolyte in multiple smart supercapacitors through the viewing window; continuing to charge the smart supercapacitor at the rated voltage under constant voltage until the electrolyte becomes colorless and transparent; then discharging the smart supercapacitor to below 0.05V and, during the discharging process, obtaining photographs of the electrolyte in multiple smart supercapacitors through the viewing window; and using the photographs to create the standard color chart. The multiple photographs obtained in the above process can indicate the electrolyte color of the supercapacitor at different voltages (i.e., different charges). Therefore, by using the above photographs to create the standard color chart, the current charge of the smart supercapacitor can be intuitively understood based on the electrolyte color and the standard color chart.

[0026] In some embodiments of the present invention, the method for producing a standard color chart includes: discharging the intelligent supercapacitor to a voltage below 0.05V, and obtaining a photograph a of the electrolyte in the intelligent supercapacitor through the perspective window; sequentially charging the intelligent supercapacitor to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% of the rated voltage, and obtaining photographs b, c, d, and d of the electrolyte in the intelligent supercapacitor at 10% of the rated voltage, 20% of the rated voltage, 30% of the rated voltage, and 100% of the electrolyte in the intelligent supercapacitor through the perspective window, respectively. Photographs e, f, g, h, i, j, and k of the electrolyte in the intelligent supercapacitor at 40% of its rated voltage, 50% of its rated voltage, 60% of its rated voltage, 70% of its rated voltage, 80% of its rated voltage, 90% of its rated voltage, and 100% of its rated voltage are shown. The intelligent supercapacitor is then continuously charged at its rated voltage under constant voltage until the electrolyte becomes colorless and transparent. The intelligent supercapacitor is then sequentially discharged to its rated voltage. At voltages below 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, and 0.05V, photographs j′, i′, h′, g′, f′, e′, and e′ of the electrolyte in the intelligent supercapacitor at 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, and 0.05V are obtained through the viewing window, showing the electrolyte at the following voltage levels: [Images j′, i′, h′, g′, g′, f′, e′, and e′]. The standard color card is made using the following photographs: d′ of the electrolyte, c′ of the electrolyte of the intelligent supercapacitor at 20% of its rated voltage, b′ of the electrolyte of the intelligent supercapacitor at 10% of its rated voltage, and a′ of the electrolyte of the intelligent supercapacitor at a voltage below 0.05V.

[0027] Understandably, the electrolyte color in a smart supercapacitor should be the same under the same voltage; for example, the colors indicated by photo a and photo a′ should be identical. Furthermore, photos obtained at different voltages are printed as labels and labeled with their corresponding charge values, and these labels are combined to create a standard color chart.

[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0030] Example 1

[0031] 1) Weigh 1.06g of yellow 1-butyl-3-methylimidazolium lactate and add it to 98.94g of isopropanol and mix well to obtain a 1.06wt% 1-butyl-3-methylimidazolium lactate solution. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium lactate solution. After the element is saturated with liquid, weigh it to obtain a saturated liquid absorption amount of 6.85g. The theoretical electrolyte capacity of the element after saturation is calculated to be 85.6F.

[0032] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 7.98g of 1.06wt% 1-butyl-3-methylimidazolium lactate solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F smart supercapacitor.

[0033] 3) First, discharge the 100F smart supercapacitor obtained in step 2) to below 0.05V. Take a high-resolution photograph of the electrolyte layer on the surface of the substrate through the viewing window and name it Photo a. Then, charge the smart supercapacitor sequentially to 0.36V, 0.72V, 1.08V, 1.44V, 1.80V, 2.16V, 2.52V, 2.88V, 3.24V, and 3.6V. Simultaneously, take high-resolution photographs of the electrolyte layer on the surface of the substrate through the viewing window and name them Photo b, Photo c, Photo d, Photo e, Photo f, Photo g, Photo h, Photo i, Photo j, and Photo k. When the 100F smart supercapacitor is charged to 3.6V, observe through the viewing window to confirm that the electrolyte layer on the surface of the substrate is colorless and transparent. Then, charge at a constant voltage of 3.6V for 5 minutes, and observe through the viewing window to confirm that the electrolyte layer on the surface of the substrate is colorless and transparent. Finally, the smart supercapacitor was discharged sequentially to below 3.24V, 2.88V, 2.52V, 2.16V, 1.80V, 1.44V, 1.08V, 0.72V, 0.36V and 0.05V. At the same time, high-resolution photos of the electrolyte layer on the surface of the substrate were taken through the viewing window and named sequentially as photo j′, photo i′, photo h′, photo g′, photo f′, photo e′, photo d′, photo c′, photo b′ and photo a′.

[0034] 4) Compare photos a and a′, b and b′, ​​c and c′, d and d′, e and e′, f and f′, g and g′, h and h′, i and i′, j and j′ respectively to confirm that the colors of the corresponding photos are completely the same. Select one of photos a, b, c, d, e, f, g, h, i, j, and k or the corresponding discharge photos to make a standard color card and mark the corresponding charge values ​​as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% in sequence. Print the standard color card and charge value labels and paste them onto the 100F smart supercapacitor obtained in step 3) to obtain the finished 100F smart supercapacitor with the standard color card.

[0035] Example 2

[0036] 1) Weigh 1.77g of yellow 1-butyl-3-methylimidazolium tribromide and add it to 98.23g of isopropanol and mix well to obtain a 1.77wt% 1-butyl-3-methylimidazolium tribromide solution. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium tribromide solution. After the element is saturated with liquid, weigh it and find that the saturated liquid absorption of the element is 6.92g. The theoretical capacity of the electrolyte after the element is saturated with liquid is calculated to be 86.5F.

[0037] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 8.00g of 1.77wt% 1-butyl-3-methylimidazolium tribromide solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F smart supercapacitor.

[0038] Steps 3) and 4) are the same as in Example 1, and a 100F smart supercapacitor with a standard color card is prepared.

[0039] Example 3

[0040] 1) Weigh 1.57g of brown 1-butyl-3-methylimidazolium tetrachloroferrate and add it to 98.43g of isopropanol and mix well to obtain a 1.57wt% 1-butyl-3-methylimidazolium tetrachloroferrate solution. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium tetrachloroferrate solution. After the element is saturated with liquid, weigh it to obtain a saturated liquid absorption amount of 6.89g. The theoretical electrolyte capacity of the element after saturation is calculated to be 86.1F.

[0041] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 7.99g of 1.57wt% 1-butyl-3-methylimidazolium tetrachloroferrate solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F smart supercapacitor.

[0042] Steps 3) and 4) are the same as in Example 1, and a 100F smart supercapacitor with a standard color card is prepared.

[0043] Example 4

[0044] 1) Weigh 2.06g of black 1-butyl-3-methylimidazolium aluminum chloride and add it to 97.94g of isopropanol and mix well to obtain a 2.06wt% 1-butyl-3-methylimidazolium aluminum chloride solution. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium aluminum chloride solution. After the element is saturated with liquid, weigh it to obtain a saturated liquid absorption amount of 7.11g. The theoretical electrolyte capacity of the element after saturation is calculated to be 88.9F.

[0045] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 8.50g of 2.06wt% 1-butyl-3-methylimidazolium aluminum chloride salt solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F smart supercapacitor.

[0046] Steps 3) and 4) are the same as in Example 1, and a 100F smart supercapacitor with a standard color card is prepared.

[0047] Comparative Example 1

[0048] 1) The vacuum-dried 100F supercapacitor element was immersed in the Xinzhoubang DLC301 electrolyte. After the element was saturated with the electrolyte, the saturated electrolyte absorption was measured to be 7.35g. The theoretical electrolyte capacity of the element after saturation was calculated to be 854F.

[0049] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, put the vacuum-dried 100F supercapacitor element into the shell and inject 8.58g of Xinzhoubang DLC301 electrolyte. Then, seal and age the element after injection to obtain a 100F supercapacitor.

[0050] 3) First, discharge the 100F supercapacitor obtained in step 2) to below 0.05V. Observation through the viewing window shows that the electrolyte layer on the surface of the element is colorless and transparent. Then, charge the supercapacitor sequentially to 0.27V, 0.54V, 0.81V, 1.08V, 1.35V, 1.62V, 1.89V, 2.16V, 2.43V, and 2.7V. Observation through the viewing window shows that the electrolyte layer on the surface of the element remains colorless and transparent. Then, charge at a constant voltage of 2.7V for 5 minutes. Finally, discharge the supercapacitor sequentially to below 2.43V, 2.16V, 1.89V, 1.62V, 1.35V, 1.08V, 0.81V, 0.54V, 0.27V, and 0.05V. Observation through the viewing window shows that the surface of the element still remains colorless and transparent. Since the electrolyte layer on the surface of the supercapacitor does not change color across the entire voltage range, it is impossible to achieve "intelligent" operation of the supercapacitor.

[0051] Comparative Example 2

[0052] 1) Weigh 6.00g of yellow 1-butyl-3-methylimidazolium lactate and add it to 94.00g of isopropanol and mix well to obtain a 1-butyl-3-methylimidazolium lactate solution with a concentration of 6.00wt%. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium lactate solution. After the element is saturated with liquid, weigh it to obtain a saturated liquid absorption amount of 6.88g. The theoretical electrolyte capacity of the element after saturation is calculated to be 486.9F.

[0053] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 7.98g of 6.00wt% 1-butyl-3-methylimidazolium lactate solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F smart supercapacitor.

[0054] 3) First, discharge the 100F smart supercapacitor obtained in step 2) to below 0.05V. Take a high-resolution photograph of the electrolyte layer on the surface of the substrate through the viewing window and name it Photo a. Then, charge the smart supercapacitor sequentially to 0.36V, 0.72V, 1.08V, 1.44V, 1.80V, 2.16V, 2.52V, 2.88V, 3.24V, and 3.6V. Simultaneously, take high-resolution photographs of the electrolyte layer on the surface of the substrate through the viewing window and name them Photo b, Photo c, Photo d, Photo e, Photo f, Photo g, Photo h, Photo i, Photo j, and Photo k. When the 100F smart supercapacitor is charged to 3.6V, the electrolyte layer on the surface of the substrate is observed to be pale yellow through the viewing window. Because the color change of the electrolyte layer on the surface of the substrate is not significant during the charging process of the smart supercapacitor, it is difficult to achieve the "intelligentization" of the supercapacitor.

[0055] Comparative Example 3

[0056] 1) Weigh 0.45g of yellow 1-butyl-3-methylimidazolium lactate and add it to 99.55g of isopropanol and mix well to obtain a 0.45wt% 1-butyl-3-methylimidazolium lactate solution. Immerse the vacuum-dried 100F supercapacitor element in the 1-butyl-3-methylimidazolium lactate solution. After the element is saturated with liquid, weigh it to obtain a saturated liquid absorption amount of 6.82g. The theoretical electrolyte capacity of the element after saturation is calculated to be 36.2F.

[0057] 2) Customize a Φ22×48mm shell with a PAM plate viewing window. First, vacuum-dried 100F supercapacitor elements are placed into the shell and then 7.98g of 0.45wt% 1-butyl-3-methylimidazolium lactate solution is injected. Then, the elements after injection are sealed and aged to obtain a 100F supercapacitor.

[0058] 3) First, discharge the 100F supercapacitor obtained in step 2) to below 0.05V. Take a high-resolution photograph of the electrolyte layer on the surface of the substrate through the viewing window and name it photo a. Then, charge the supercapacitor sequentially to 0.36V, 0.72V, 1.08V, 1.44V, 1.80V, 2.16V, 2.52V, 2.88V, 3.24V, and 3.6V. Simultaneously observe the color change of the electrolyte layer on the surface of the substrate through the viewing window. It can be found that when the supercapacitor is charged to above 1.44V, the electrolyte layer on the surface of the substrate is colorless and transparent. Therefore, it is impossible to achieve "intelligent" operation of the supercapacitor across the entire voltage range.

[0059] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A smart supercapacitor, characterized in that, include: Supercapacitor elements, electrolyte, and casing; The supercapacitor element includes an electrode and a fiber diaphragm, and the supercapacitor element is impregnated with the electrolyte, which includes a room temperature ionic liquid and a solvent; The housing includes a viewing window configured to allow observation of the color of the electrolyte through the viewing window; The room temperature ionic liquid is at least one of the following: red room temperature ionic liquid, yellow room temperature ionic liquid, green room temperature ionic liquid, blue room temperature ionic liquid, indigo room temperature ionic liquid, purple room temperature ionic liquid, yellow-red room temperature ionic liquid, black room temperature ionic liquid, and brown room temperature ionic liquid. The yellow room-temperature ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium lactate, 1-butyl-3-methylimidazolium tribromide, 1-butyl-3-methylimidazolium thiocyanate, 1-hexyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium chloride; the yellow-red room-temperature ionic liquid is selected from 1-ethyl-3-methylimidazolium diethyl phosphate; the brown room-temperature ionic liquid is selected from at least one of trioctylmethylammonium sulfate and 1-butyl-3-methylimidazolium tetrachloroferrate; and the black room-temperature ionic liquid is selected from 1-butyl-3-methylimidazolium aluminum chloride. In the electrolyte, the concentration of the room-temperature ionic liquid is 0.5 wt% to 5 wt%. A standard color chart is provided on the outer casing, and the standard color chart indicates the color of the electrolyte of the smart supercapacitor under different voltages.

2. The intelligent supercapacitor according to claim 1, characterized in that, The solvent is selected from at least one of C1-8 alkyl monohydric alcohols, C1-8 alkyl dihydric alcohols, glycerol, acetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluorobenzene, chlorobenzene, and bromobenzene.

3. The intelligent supercapacitor according to claim 1, characterized in that, The fiber diaphragm is white.

4. The intelligent supercapacitor according to claim 1, characterized in that, The material of the viewing window is selected from at least one of tempered glass, PVC board, polymethyl methacrylate, polystyrene, polycarbonate, styrene-acrylonitrile copolymer, and colorless diamond.

5. A method for preparing the intelligent supercapacitor according to any one of claims 1 to 4, characterized in that, include: The supercapacitor element is inserted into the casing, injected with electrolyte, sealed and aged to obtain the intelligent supercapacitor. The amount of electrolyte injected is 110% to 120% of the saturated electrolyte absorption capacity of the supercapacitor element.

6. The method according to claim 5, characterized in that, Further, it includes creating a standard color card and placing the standard color card on the outer casing; The production of the standard color chart includes: The intelligent supercapacitor is discharged to below 0.05 V, and a photograph of the electrolyte in the intelligent supercapacitor is obtained through the transparent window; The smart supercapacitor is charged to its rated voltage, and during the charging process, photographs of the electrolyte in multiple smart supercapacitors are taken through the viewing window; Continue to charge the smart supercapacitor at the rated voltage until the electrolyte becomes colorless and transparent. Then discharge the smart supercapacitor to below 0.05 V. During the discharge process, take pictures of the electrolyte in multiple smart supercapacitors through the viewing window. The standard color chart is created using the photograph.

7. The method according to claim 6, characterized in that, The production of the standard color chart includes: The intelligent supercapacitor is discharged to a voltage below 0.05 V, and a photograph a of the electrolyte in the intelligent supercapacitor is obtained through the perspective window; The intelligent supercapacitor was sequentially charged to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% of its rated voltage. Through the viewing window, photographs were taken of the electrolyte at the following voltage levels: b) at 10% of the rated voltage, c) at 20% of the rated voltage, d) at 30% of the rated voltage, e) at 40% of the rated voltage, f) at 50% of the rated voltage, g) at 60% of the rated voltage, h) at 70% of the rated voltage, i) at 80% of the rated voltage, j) at 90% of the rated voltage, and k) at 100% of the rated voltage. Continue charging the intelligent supercapacitor at the rated voltage under constant voltage until the electrolyte becomes colorless and transparent. Then, sequentially discharge the intelligent supercapacitor to 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, and 0.05% of the rated voltage. Below V, the following photographs are obtained through the perspective window: j′ of the electrolyte at 90% of the rated voltage, i′ of the electrolyte at 80% of the rated voltage, h′ of the electrolyte at 70% of the rated voltage, g′ of the electrolyte at 60% of the rated voltage, f′ of the electrolyte at 50% of the rated voltage, e′ of the electrolyte at 40% of the rated voltage, d′ of the electrolyte at 30% of the rated voltage, c′ of the electrolyte at 20% of the rated voltage, b′ of the electrolyte at 10% of the rated voltage, and a′ of the electrolyte when the voltage of the smart supercapacitor is below 0.05 V. The standard color chart is created using the photograph a or a′, the photograph b or b′, the photograph c or c′, the photograph d or d′, the photograph e or e′, the photograph f or f′, the photograph g or g′, the photograph h or h′, the photograph i or i′, the photograph j or j′, and the photograph k.