A supercapacitor working electrode, a preparation method thereof and a supercapacitor

Abstract

This application discloses a supercapacitor working electrode, its fabrication method, and the supercapacitor itself, belonging to the field of capacitor technology. The supercapacitor working electrode of this application comprises a conductive substrate and an electrode active layer grown in situ on the surface of the conductive substrate. The electrode active layer comprises an inorganic metal oxide nanocrystalline film, which is a continuous conductive structure formed by the interconnection of single chiral inorganic metal oxide nanocrystals. The supercapacitor working electrode of this application possesses a chiral-induced spin-selectivity effect, achieving spin-polarized charge transport without relying on magnetohydrodynamic convection / Lorentz force driving, effectively improving the specific capacitance, rate performance, and cycle stability of the supercapacitor.

Description

Technical Field

[0001] This application belongs to the field of electrochemical energy storage device technology, and specifically discloses a supercapacitor working electrode, its preparation method and the supercapacitor. Background Technology

[0002] Supercapacitors, with their advantages of fast charge / discharge rates and long cycle life, have become an ideal choice for next-generation energy storage devices. However, the inherent limitations of electron transfer kinetics at the electrode / electrolyte interface result in significant bottlenecks in the energy density and rate performance of supercapacitors, making it difficult to meet the application requirements of high-performance energy storage scenarios. Therefore, improving the interfacial charge transport capability of supercapacitors is of great significance.

[0003] Currently, related fields have disclosed methods to optimize electrode performance through pseudocapacitive redox engineering surface design, composite electrode structure design, and interface polarization modulation, thereby enhancing charge transfer kinetics and bringing the energy density and rate performance of supercapacitors close to improvement bottlenecks. Among these, interface polarization modulation is an optimization strategy that utilizes electron spin to regulate electrochemical reaction kinetics. Specifically, it relies on an external magnetic field to regulate electron spin and suppress scattering to reduce the charge transfer barrier, thus improving electrochemical kinetic performance.

[0004] However, existing interface polarization control strategies have the following inherent defects, which hinder practical applications: First, the magnets on which the applied magnetic field depends will increase the size of the device, reduce the portability of the device, and maintaining the stability of the applied magnetic field will also generate additional energy consumption, increasing the operating cost of the device; Second, the magnets have poor compatibility with flexible / lightweight electrode materials, making it difficult to integrate them into compact / flexible energy storage devices, thus limiting the adaptability of flexible / miniaturized energy storage devices. Summary of the Invention

[0005] This application discloses a working electrode for a supercapacitor, its preparation method, and the supercapacitor itself, aiming to solve the technical problem that the existing interface polarization control relies on an external magnetic field, which limits its practical application.

[0006] To achieve the above objectives, the technical solution provided in this application is as follows: A first aspect of this application provides a supercapacitor working electrode, the supercapacitor working electrode comprising: Conductive substrate; and An electrode active layer is grown in situ on the surface of the conductive substrate. The electrode active layer comprises an inorganic metal oxide nanocrystalline film, which is a continuous conductive structure formed by interconnecting single chiral inorganic metal oxide nanocrystals.

[0007] According to the preferred disclosure of the first aspect, the chiral inorganic metal oxide nanocrystals are one or more of L / D-chiral cobalt tetroxide nanocrystals, L / D-chiral nickel oxide nanocrystals, L / D-chiral ferric oxide nanocrystals, L / D-chiral manganese oxide nanocrystals, and L / D-chiral copper oxide nanocrystals.

[0008] According to the preferred disclosure of the first aspect, the conductive substrate comprises fluorine-doped tin oxide conductive glass, nickel foam, and carbon cloth.

[0009] The second aspect of this application also discloses a method for preparing the working electrode of the supercapacitor described above, which includes the following steps: A chiral metal hydroxide precursor film was prepared in situ grown on the surface of a conductive substrate by immersing the surface of the conductive substrate in a mixed aqueous solution containing a metal ion source compound, a chiral molecule and a pH adjuster. The chiral metal hydroxide precursor film is calcined in an oxygen atmosphere at 350-550°C for 1-6 hours to obtain the working electrode of the supercapacitor.

[0010] According to the preferred disclosure of the second aspect, the chiral molecule is selected from one or more of L-threonine, D-threonine, L-proline, and D-proline.

[0011] According to the preferred disclosure of the second aspect, the molar ratio of the metal ion source compound to the chiral molecule is 1:(1.5~2).

[0012] According to the preferred disclosure of the second aspect, the pH adjuster comprises urea and ammonia.

[0013] According to the preferred disclosure of the second aspect, the hydrothermal reaction temperature of the hydrothermal method is 80~150℃, and the time is 10~18 hours.

[0014] A third aspect of this application also discloses a symmetrical supercapacitor. This symmetrical supercapacitor is assembled from a working electrode, a counter electrode, a reference electrode, and an electrolyte, wherein the working electrode is the working electrode of the supercapacitor described in this application.

[0015] A fourth aspect of this application also discloses an asymmetric supercapacitor. This asymmetric supercapacitor is assembled from a positive electrode, a negative electrode, a separator, and a gel electrolyte, wherein the positive electrode is the working electrode of the supercapacitor described in this application.

[0016] Compared with the prior art, the advantages or beneficial effects of this application include at least: This application achieves a chiral-induced spin selectivity effect in the working electrode of a supercapacitor by in-situ growing a continuous conductive thin film formed by interconnecting single chiral inorganic metal oxide nanocrystals on a conductive substrate surface. On the one hand, it enables spin-polarized charge transport without relying on magnetohydrodynamic convection / Lorentz force, avoiding the problems of high operating energy consumption and adaptation limitations caused by external magnetic field dependence, thus expanding the scope of application. On the other hand, spin polarization can be used as the dominant enhancement mechanism, effectively reducing the probability of spin-flip scattering during interface electron transfer and lowering the non-adiabatic activation barrier associated with spin-forbidden transitions, thereby increasing the transport rate at the electrode / electrolyte interface and significantly reducing the charge transfer resistance. Furthermore, spin polarization transport can regulate the local electronic states on the electrode surface, promoting uniform charge distribution, effectively alleviating the local charge accumulation of a minority of spin carriers, facilitating ion diffusion in the electric double layer and suppressing the occurrence of side reactions. Based on the above synergistic effects, the specific capacitance, rate performance, and cycle stability of the supercapacitor are improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 Surface morphology and cross-sectional SEM images of L-Co(OH2) precursor films supported on L-Co(OH2) / FTO precursor electrodes and L-Co3O4 films supported on L-Co3O4 / FTO electrodes provided in this application; Figure 2 TEM image of L-Co3O4 nanocrystalline thin film supported on L-Co3O4 / FTO electrode provided in this application; Figure 3 XPS spectra of L-Co(OH2) precursor films supported on L-Co(OH2) / FTO precursor electrodes and L-Co3O4 films supported on L-Co3O4 / FTO electrodes provided in this application; Figure 4 XRD patterns of L-Co(OH2) precursor films supported on L-Co(OH2) / FTO precursor electrodes and L-Co3O4 films supported on L-Co3O4 / FTO electrodes provided in this application; Figure 5 CD spectra of L-Co3O4 thin films supported on L-Co3O4 / FTO electrodes and D-Co3O4 thin films supported on D-Co3O4 / FTO electrodes provided in this application; Figure 6 Spin polarization efficiency diagrams of the L-Co3O4 / FTO and D-Co3O4 / FTO electrodes provided in this application; Figure 7 Cyclic voltammetry curves of symmetrical supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and L-Co3O4 / nickel foam electrode respectively, provided for this application; Figure 8 Constant current charge-discharge test diagrams of symmetrical supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and L-Co3O4 / nickel foam electrode respectively, provided for this application; Figure 9 A comparison of rate performance and kinetic analysis of the symmetrical supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and L-Co3O4 / nickel foam electrode, respectively, provided for this application; Figure 10 Comparison of the cycle stability of the symmetrical supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and L-Co3O4 / nickel foam electrode respectively provided in this application; Figure 11 Electrochemical impedance spectroscopy and relaxation time distribution (DRT) analysis results of symmetrical supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and L-Co3O4 / nickel foam electrode respectively, provided for this application; Figure 12 Cyclic voltammetry curves of the asymmetric supercapacitors assembled from No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode and D-Co3O4 / nickel foam electrode respectively, provided for this application; Figure 13 A functionalized illustration of the asymmetric supercapacitor assembled from D-Co3O4 / nickel foam electrodes provided for this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort are within the scope of protection of this application.

[0020] In the descriptions related to this application, the term "and / or" is used to describe the relationship between related objects, indicating the existence of three relationships. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. Here, A and B can be singular or plural; the symbol " / " means "or".

[0021] In the descriptions related to this application, the term "at least one" refers to one or more, and "multiple" refers to two or more; the term "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of A, B, or C" or "at least one of A, B, and C" can mean any one of A, B, and C, or A+B, or A+C, or B+C, or A+B+C, where A, B, and C can be single or multiple.

[0022] In the description of this application, the order of the serial numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be specifically determined by its function and internal logic, and does not constitute any limitation on the execution process of this embodiment.

[0023] In the description of this application, the numerical range should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Any intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within a stated range, are also included in this embodiment, and the upper and lower limits of the smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, the technical / scientific terms used in this application have the meanings commonly understood by one of ordinary skill in the art. While this application describes only preferred materials and methods, similar or equivalent methods and materials may be used in specific embodiments or test cases. All references to this application are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this application shall prevail.

[0025] To address the technical problem that existing interface polarization modulation methods limit their adaptability to flexible / miniaturized energy storage devices due to inherent defects, a first aspect of this application provides a supercapacitor working electrode. The supercapacitor working electrode of this application comprises a conductive substrate and an electrode active layer grown in situ on the surface of the conductive substrate. The electrode active layer comprises an inorganic metal oxide nanocrystalline film, wherein the inorganic metal oxide nanocrystalline film is a continuous conductive structure formed by interconnecting single chiral inorganic metal oxide nanocrystals.

[0026] It should be noted that the chiral inorganic metal oxide nanocrystals in this application refer to inorganic metal oxide nanocrystals with chiral optical characteristics, including but not limited to L / D-chiral cobalt tetroxide nanocrystals (L / D-Co3O4), L / D-chiral nickel oxide nanocrystals (L / D-NiO), L / D-chiral ferric oxide nanocrystals (L / D-Fe2O3), L / D-chiral manganese oxide nanocrystals (L / D-Mn2O3), and L / D-chiral copper oxide nanocrystals (L / D-CuO). In this application, L-Co3O4 and D-Co3O4 are used as examples to illustrate the feasibility of constructing inorganic metal oxide nanocrystalline thin films with chiral spin-selective effects using chiral inducing agents. This does not constitute any limitation on the scope of protection. The above-mentioned L / D-NiO, L / D-Fe2O3, L / D-Mn2O3, L / D-CuO, etc. are also applicable to the technical solutions of this application, and will not be exemplified one by one in this application.

[0027] This application achieves a chiral-induced spin selectivity effect in the electrode by in-situ growing a continuous conductive thin film formed by interconnecting single chiral inorganic metal oxide nanocrystals on a conductive substrate. This enables spin-polarized charge transport without relying on magnetohydrodynamic convection / Lorentz force, avoiding the high energy consumption and compatibility limitations caused by external magnetic field dependence, thus expanding its applicability. Furthermore, spin polarization can be used as the dominant enhancement mechanism, effectively reducing the probability of spin-flip scattering during interfacial electron transfer and lowering the non-adiabatic activation barrier associated with spin-forbidden transitions, thereby increasing the transport rate at the electrode / electrolyte interface and significantly reducing charge transfer resistance. Additionally, spin polarization transport can regulate the local electronic states on the electrode surface, promoting uniform charge distribution, effectively alleviating the local charge accumulation of a minority of spin carriers, facilitating ion diffusion in the electric double layer, and suppressing side reactions. Based on these synergies, the specific capacitance, rate performance, and cycle stability of the supercapacitor are improved.

[0028] It should be noted that the conductive substrate in this application refers to a substrate material with good conductivity, capable of supporting active materials, and suitable for electrochemical systems, including but not limited to fluorine-doped tin oxide conductive glass (FTO conductive glass), nickel foam (NF), and carbon cloth (CC). In this application, FTO conductive glass and nickel foam (NF) are used as examples to illustrate the feasibility and versatility of in-situ growth of inorganic metal oxide nanocrystalline films with spin-selective effects on the surface of a conductive substrate via hydrothermal methods. This does not constitute any limitation on the scope of protection. Carbon cloth (CC) is also applicable to the technical solution of this application, and will not be exemplified individually here.

[0029] The second aspect of this application provides a method for preparing the working electrode of the supercapacitor of this application, preferably comprising the following steps: A chiral metal hydroxide precursor film was prepared in situ grown on the surface of a conductive substrate by immersing the surface of the conductive substrate in a mixed aqueous solution containing a metal ion source compound, a chiral molecule and a pH adjuster. The chiral metal hydroxide precursor film is calcined in an oxygen atmosphere at 350-550°C for 1-6 hours to obtain the working electrode of the supercapacitor.

[0030] Based on the above description, this application can construct an inorganic metal oxide nanocrystalline active film with chiral induced spin selectivity on the surface of a conductive substrate in only two steps: hydrothermal growth and calcination. This enables the fabrication of a spin-polarized charge transport electrode that does not rely on magnetohydrodynamic convection / Lorentz force. The process is simple, the conditions are mild, and the reproducibility is good, making it suitable for large-scale production.

[0031] It should be noted that the metal ion source compound in this application refers to a compound with good water solubility that can provide a metal element precursor for the synthesis of chiral inorganic metal oxide nanocrystals, including but not limited to cobalt salts, nickel salts, iron salts, manganese salts, and copper salts. This application does not limit the specific types of each metal salt; they can be common metal salts known in the art, such as cobalt nitrate hexahydrate.

[0032] It should be noted that the chiral molecules in this application refer to chiral inducible organic compounds containing a chiral center and possessing specific coordination ability, including but not limited to L-threonine, D-threonine, L-proline, and D-proline. This application does not specify the exact source of the above chiral molecules; they can be obtained through commercial purchases or self-synthesis, provided that the purity requirements are met.

[0033] It should be noted that the preferred molar ratio of the metal ion source compound to the chiral molecule in this application is 1:(1.5~2) to ensure the preparation of a chiral metal hydroxide precursor film with a regular structure and to improve the spin-selective transport performance.

[0034] It should be noted that the pH adjuster in this application refers to an organic / inorganic base without the introduction of metal ions, including but not limited to urea, ammonia, etc. This application does not specify the exact amount of pH adjuster to be added; the standard is to prepare inorganic metal oxide nanocrystals with complete morphology. Those skilled in the art can adapt different optimal pH ranges according to the growth requirements of different target nanocrystals. For example, when preparing L / D-chiral cobalt tetroxide nanocrystals, a pH adjuster is added to adjust the pH of the mixed aqueous solution to 6.5~8; when preparing L / D-chiral nickel oxide nanocrystals, a pH adjuster is added to adjust the pH of the mixed aqueous solution to 9.5~10.5.

[0035] It should be noted that the preferred hydrothermal reaction temperature for the hydrothermal method in this application is 80~150℃, and the reaction time is 10~18 hours. The embodiments in this application use a hydrothermal reaction temperature of 100℃ and a reaction time of 6 hours as an example to illustrate the feasibility of hydrothermal growth of inorganic metal oxide nanocrystalline thin films with chiral induced spin selectivity, and do not constitute any limitation on the scope of protection. Any parameters falling within the above preferred range are applicable to the technical solution of this application, and will not be exemplified individually here.

[0036] A third aspect of this application also provides a symmetrical supercapacitor, preferably assembled from a working electrode, a counter electrode, a reference electrode, and an electrolyte. The counter electrode is preferably a platinum sheet electrode commonly used in electrochemical testing, and the reference electrode is preferably a Hg / HgO electrode commonly used in energy storage devices. The electrolyte is preferably an alkaline electrolyte, such as a 1 mol / L KOH aqueous solution. Based on the chiral-induced spin-selectivity effect of the working electrode of this application's supercapacitor, the assembled symmetrical supercapacitor can achieve spin-polarized charge transport without an external magnetic field, giving it higher specific capacitance, excellent rate performance, and good cycle stability.

[0037] A fourth aspect of this application also provides an asymmetric supercapacitor, preferably assembled with the working electrode of the supercapacitor of this application as the positive electrode, together with a negative electrode, a separator, and a gel electrolyte. The negative electrode is preferably an activated carbon@nickel foam negative electrode; the gel electrolyte is preferably a polyvinyl alcohol / potassium hydroxide gel electrolyte. Based on the chiral-induced spin-selectivity effect of the working electrode of the supercapacitor of this application, the assembled asymmetric supercapacitor can achieve spin-polarized charge transport under conditions without an external magnetic field, giving the asymmetric supercapacitor higher specific capacitance, excellent rate performance, and good cycle stability.

[0038] The technical solution of this application will be further described below with reference to specific embodiments.

[0039] Example 1 This example provides an L-Co3O4 / FTO electrode, and the preparation process is as follows: S101: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of L-threonine. Stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S102: After cleaning the FTO conductive glass (2cm×1cm) with boiling acetone and boiling ethanol for 10 minutes each, place the FTO conductive glass tilted on the inner wall of the reaction vessel with the conductive side facing down, add the mixed aqueous solution from the previous step, seal and hydrothermally react at 100℃ for 6 hours. After the reaction is completed, take out the substrate and ultrasonically clean it with deionized water and ethanol to remove residues. Dry it at room temperature to obtain the L-Co(OH2) / FTO precursor electrode. S103: Calcine the L-Co(OH2) / FTO precursor electrode from the previous step at 450℃ for 2 hours to obtain the L-Co3O4 / FTO electrode.

[0040] Example 2 This example provides a D-Co3O4 / FTO electrode, and the preparation process is as follows: S101: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of D-threonine. Stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S102: After cleaning the FTO conductive glass (2cm×1cm) with boiling acetone and boiling ethanol for 10 minutes each, place the FTO conductive glass tilted on the inner wall of the reaction vessel with the conductive side facing down, add the mixed aqueous solution from the previous step, seal and hydrothermally react at 100℃ for 6 hours. After the reaction is completed, take out the substrate and ultrasonically clean it with deionized water and ethanol to remove residues. Dry it at room temperature to obtain the D-Co(OH2) / FTO precursor electrode. S103: Calcine the D-Co(OH2) / FTO precursor electrode from the previous step at 450℃ for 2 hours to obtain the D-Co3O4 / FTO electrode.

[0041] Example 3 This example provides an L-Co3O4 / nickel foam electrode, the preparation process of which is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of L-threonine. Stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S2: The nickel foam (1cm×1cm) was cleaned with boiling acetone and boiling ethanol for 10 minutes each, then ultrasonicated with 1M dilute hydrochloric acid for 10 minutes to remove the oxide layer, and vacuum dried at 40℃. The nickel foam was then placed vertically in the reaction vessel, the mixed aqueous solution from the previous step was added, the vessel was sealed, and hydrothermal reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the substrate was removed and ultrasonically cleaned with deionized water and ethanol to remove residues. The substrate was then dried at room temperature to obtain the L-Co(OH2) / nickel foam precursor electrode. S3: Calcine the L-Co(OH2) / nickel foam precursor electrode from the previous step at 450℃ for 2 hours to obtain the L-Co3O4 / nickel foam electrode.

[0042] Example 4 This example provides a D-Co3O4 / nickel foam electrode, the preparation process of which is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of D-threonine. Stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S2: The nickel foam (1cm×1cm) was cleaned with boiling acetone and boiling ethanol for 10 minutes each, then ultrasonicated with 1M dilute hydrochloric acid for 10 minutes to remove the oxide layer, and vacuum dried at 40℃. The nickel foam was then placed vertically in the reaction vessel, the mixed aqueous solution from the previous step was added, the vessel was sealed, and hydrothermal reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the substrate was removed and ultrasonically cleaned with deionized water and ethanol to remove residues. The substrate was then dried at room temperature to obtain the D-Co(OH2) / nickel foam precursor electrode. S3: Calcine the D-Co(OH2) / nickel foam precursor electrode from the previous step at 450℃ for 2 hours to obtain the L or D-Co3O4 / nickel foam electrode.

[0043] To illustrate the structural properties of the L-Co3O4 / FTO electrode, D-Co3O4 / FTO electrode, L-Co3O4 / nickel foam electrode and D-Co3O4 / nickel foam electrode described in this application, comparative examples 1 to 4 are also provided.

[0044] Comparative Example 1 This example provides a No-additive Co3O4 / FTO electrode, and the preparation process is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of deionized water containing 2 mmol of urea, stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S2: After cleaning the FTO conductive glass (2cm×1cm) with boiling acetone and boiling ethanol for 10 minutes each, place the FTO conductive glass tilted on the inner wall of the reaction vessel with the conductive side facing down, add the mixed aqueous solution from the previous step, seal and hydrothermally react at 100℃ for 6 hours. After the reaction is completed, take out the substrate and ultrasonically clean it with deionized water and ethanol to remove residues. Dry it at room temperature to obtain the No-additive Co(OH2) / FTO precursor electrode. S3: Calcine the No-additive Co(OH2) / FTO precursor electrode from the previous step at 450℃ for 2 hours to obtain the No-additive Co3O4 / FTO electrode.

[0045] Comparative Example 2 This example provides a Rac-Co3O4 / FTO electrode, and the preparation process is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of racemic threonine (a mixture of L-threonine and D-threonine in a molar ratio of 1:1). Stir at room temperature for 20 minutes to obtain a mixed aqueous solution. S2: After cleaning the FTO conductive glass (2cm×1cm) with boiling acetone and boiling ethanol for 10 minutes each, place the FTO conductive glass tilted on the inner wall of the reaction vessel with the conductive side facing down, add the mixed aqueous solution from the previous step, seal and hydrothermally react at 100℃ for 6 hours. After the reaction is completed, take out the substrate and ultrasonically clean it with deionized water and ethanol to remove residues. Dry it at room temperature to obtain the Rac-Co(OH2) / FTO precursor electrode. S3: Calcine the Rac-Co(OH2) / FTO precursor electrode from the previous step at 450℃ for 2 hours to obtain the Rac-Co3O4 / FTO electrode.

[0046] Comparative Example 3 This example provides a No-additive Co3O4 / nickel foam electrode, and the preparation process is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of deionized water containing 2 mmol of urea, stir at room temperature for 20 minutes to obtain a mixed aqueous solution; S2: The nickel foam (1cm×1cm) was cleaned with boiling acetone and boiling ethanol for 10 minutes each, then ultrasonicated with 1M dilute hydrochloric acid for 10 minutes to remove the oxide layer, and vacuum dried at 40℃. The nickel foam was then placed vertically in the reaction vessel, the mixed aqueous solution from the previous step was added, the vessel was sealed, and hydrothermal reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the substrate was removed and ultrasonically cleaned with deionized water and ethanol to remove residues. The substrate was then dried at room temperature to obtain the No-additive Co(OH2) / nickel foam precursor electrode. S3: Calcine the No-additive Co(OH2) / nickel foam precursor electrode from the previous step at 450℃ for 2 hours to obtain the No-additive Co3O4 / FTO electrode.

[0047] Comparative Example 4 This example provides a Rac-Co3O4 / nickel foam electrode, and the preparation process is as follows: S1: Dissolve 0.6 mmol of cobalt nitrate hexahydrate in 1 mL of deionized water, then add 19 mL of a deionized aqueous solution containing 2 mmol of urea and 0.9 mmol of racemic threonine (a mixture of L-threonine and D-threonine in a molar ratio of 1:1). Stir at room temperature for 20 minutes to obtain a mixed aqueous solution. S2: The nickel foam (1cm×1cm) was cleaned with boiling acetone and boiling ethanol for 10 minutes each, then ultrasonicated with 1M dilute hydrochloric acid for 10 minutes to remove the oxide layer, and vacuum dried at 40℃. The nickel foam was then placed vertically in the reaction vessel, the mixed aqueous solution from the previous step was added, the vessel was sealed, and hydrothermal reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the substrate was removed and ultrasonically cleaned with deionized water and ethanol to remove residues. The substrate was then dried at room temperature to obtain the Rac-Co(OH2) / nickel foam precursor electrode. S3: Calcine the Rac-Co(OH2) / nickel foam precursor electrode from the previous step at 450℃ for 2 hours to obtain the Rac-Co3O4 / nickel foam electrode.

[0048] Test Example 1 To clearly observe the structural features, this application uses L-Co(OH2) / FTO precursor electrode, L-Co3O4 / FTO electrode, D-Co(OH2) / FTO precursor electrode and D-Co3O4 / FTO electrode as test samples for structural characterization.

[0049] 1.1 SEM characterization The surface morphology and cross-sectional SEM characterization of the L-Co(OH2) / FTO precursor electrode and L-Co3O4 / FTO electrode were performed using a Zeiss Gemini field emission scanning electron microscope (FESEM). The results are as follows: Figure 1 As shown in the figure, ac is the SEM image of the surface morphology of the L-Co(OH2) precursor film supported on the L-Co(OH2) / FTO precursor electrode; df is the SEM image of the surface morphology of the L-Co3O4 film supported on the L-Co3O4 / FTO electrode; and ji is the SEM image of the cross-section of the L-Co(OH2) precursor film supported on the L-Co(OH2) / FTO precursor electrode.

[0050] according to Figure 1 As can be seen in (ac), the L-Co(OH2) precursor film supported on the L-Co(OH2) / FTO precursor electrode is composed of densely packed nanosheets; according to Figure 1 As can be seen from the image, the L-Co(OH2) precursor film has a lateral dimension of 200-300 nm, a thickness of approximately 20 nm, and a height of approximately 1 μm, and is vertically aligned on the FTO substrate; according to Figure 1As can be seen in (df), after calcination, the continuous nanosheets are transformed into nanofilms composed of interconnected L-Co3O4 nanocrystals.

[0051] 1.2 TEM characterization The L-Co3O4 nanocrystalline film supported on the L-Co3O4 / FTO electrode was scraped off, ultrasonically treated with ethanol, and dried at room temperature. The L-Co3O4 nanocrystalline film was then characterized by TEM using a Hitachi HT7800 high-contrast transmission electron microscope (HC-TEM). The results were as follows: Figure 2 As shown.

[0052] according to Figure 2 It can be seen that the average grain size of L-Co3O4 nanocrystals in the L-Co3O4 / FTO electrode-supported L-Co3O4 nanocrystal film is 12~16nm.

[0053] 1.3 XPS Test X-ray photoelectron spectroscopy (XPS) measurements of L-Co(OH2) precursor films and L-Co3O4 nanocrystalline films were performed using 300W aluminum-Ka radiation (E=1486.68eV) at ESCALABXit thermoelectric company (current 0.0108A, voltage 147955.40V, pressure <10⁻⁹mBar). The results are as follows: Figure 3 As shown.

[0054] according to Figure 3 As shown in (a), the Co 2p XPS spectrum exhibits new peaks at approximately 780 eV and 795 eV, corresponding to the mixed valence state Co in the spinel phase Co3O4. 2+ / Co 3+ ;according to Figure 3 As can be seen in (b), the O 1s spectrum shows a sharp lattice oxygen peak at about 530 eV, confirming the complete phase transformation from Co(OH)2 to Co3O4.

[0055] 1.4 XRD Characterization X-ray diffraction (XRD) analysis was performed on L-Co(OH2) precursor films and L-Co3O4 nanocrystalline films using a Co target (A=1.78892) on a Bruker D8 Advance X-ray diffractometer (scan rate 10 rpm, scan range from -5° to 90°). The results are as follows: Figure 4 As shown.

[0056] according to Figure 4As can be seen, compared with the L-Co(OH2) precursor film, the L-Co3O4 nanocrystalline film exhibits sharp diffraction peaks at 2θ of 22.2°, 36.6°, 43.2° and 52.6°, which can be indexed as the (111), (220), (311) and (400) crystal planes of the cubic spinel Co3O4 phase (JCPDS No.01-076-1802).

[0057] 1.5 CD spectral characterization The L-Co3O4 nanocrystalline thin films and D-Co3O4 nanocrystalline thin films were characterized by CD spectroscopy (scan range 200~800 nm, time interval -0.5 s, step size 1 nm, bandwidth 1 nm) using a Chirascan series spectrometer (Applied-Photo-Phy / sics Ltd, UK). The results are as follows: Figure 5 As shown.

[0058] according to Figure 5 It is evident that the L-Co3O4 nanocrystalline film exhibits a clear Cotton effect, proving that the inorganic chiral imprint can be retained after the removal of organic chiral molecules. The D-Co3O4 nanocrystalline film exhibits a Cotton effect that is mirror-symmetric to that of the L-Co3O4 nanocrystalline film.

[0059] 1.6 mCP-AFM Test The L-Co3O4 / FTO and D-Co3O4 / FTO electrodes were tested using mCP-AFM with a Cypher VRS1250 (Oxford Instruments, Asylum Research) in ORCA mode. The results were as follows: Figure 6 As shown.

[0060] according to Figure 6 As can be seen, the L-Co3O4 / FTO electrode exhibits significant spin-selective charge transport at room temperature: the current measured when the AFM tip is magnetized upwards (tip_up) is significantly higher than the current when the tip is magnetized downwards (tip_down), and the calculated spin polarization is approximately +48.2%. The D-Co3O4 / FTO electrode has the opposite spin selectivity, with a spin polarization of approximately -46.7%.

[0061] Test Example 2 Using the aforementioned No-additive Co3O4 / nickel foam electrode, Rac-Co3O4 / nickel foam electrode, and L-Co3O4 / nickel foam electrode as working electrodes, Hg / HgO electrode as reference electrode, platinum sheet as counter electrode, and 1 mol / L KOH solution as electrolyte, a symmetrical supercapacitor was assembled. Electrochemical tests were then performed on a Princeton ParSTATMC electrochemical workstation (cyclic voltammetry scan rate 10 mV / s, constant current charge-discharge test current density 1 mA / cm²). 2 The result is Figures 7 to 11 As shown. Among them, Figure 7 This is the cyclic voltammetry curve; Figure 8 The diagram shows a constant current charge-discharge test. Figure 9 For comparison of rate capability and kinetic analysis; Figure 10 For comparison of cycle stability; Figure 11 The results are from electrochemical impedance spectroscopy and relaxation time distribution (DRT) analysis.

[0062] according to Figure 7 It is evident that the CV area of ​​the L-Co3O4 / nickel foam electrode is significantly larger than that of the Rac-Co3O4 / nickel foam electrode and the No-additive Co3O4 / nickel foam electrode samples, indicating a higher charge storage capacity.

[0063] according to Figure 8 It can be seen that the L-Co3O4 / nickel foam electrode at 1 mA / cm 2 The specific capacitance is 289.29 mF / cm. 2 It is significantly higher than that of Rac-Co3O4 / nickel foam electrode (245.90 mF / cm). 2 ) and No-additive Co3O4 / nickel foam electrode (227.89mF / cm 2 ).

[0064] according to Figure 9 As can be seen in (a), within the current density range of 1~10 mA / cm², the L-Co3O4 / nickel foam electrode consistently maintains a higher specific capacitance, exhibiting superior rate performance; simultaneously, according to Figure 9 As can be seen in (b), the b-values ​​of the L-Co3O4 / nickel foam electrode (0.933 for anode and 0.996 for cathode) are higher than those of the Rac-Co3O4 / nickel foam electrode (0.895, 0.798) and the No-additiveCo3O4 / nickel foam electrode (0.829, 0.863), indicating a more significant diffusion contribution.

[0065] according to Figure 10 It can be seen that the L-Co3O4 / nickel foam electrode at 10 mA / cm 2After 2000 cycles, it retains 70.66% of the initial capacitance, which is better than Rac-Co3O4 / nickel foam electrode (66.58%) and No-additive Co3O4 / nickel foam electrode (59.45%).

[0066] according to Figure 11 The electrochemical impedance spectroscopy (EIS) of the L-Co3O4 / nickel foam electrode (ab) shows that the charge transfer resistance (Rct) is 0.133 Ω, which is about 1.6 times lower than that of the Rac-Co3O4 / nickel foam electrode (0.210 Ω) and about 6.4 times lower than that of the No-additive Co3O4 / nickel foam electrode (0.850 Ω). Meanwhile, according to... Figure 11 The DRT analysis in (c) shows that the main relaxation peak of the L-Co3O4 / nickel foam electrode shifts to a shorter time scale, and the integral peak area is significantly reduced, indicating faster diffusion-coupled pseudocapacitive dynamics and lower transmission impedance.

[0067] Test Example 3 Using the aforementioned D-Co3O4 / nickel foam electrode as the positive electrode and activated carbon / nickel foam (AC@NF) as the negative electrode, with PVA / KOH gel as the electrolyte, a porous polyethylene (PE) membrane was impregnated with the PVA / KOH gel electrolyte and placed between the positive and negative electrodes as a separator. After encapsulation under a certain pressure to form a soft-pack asymmetric supercapacitor, electrochemical tests were performed, and the results were... Figure 12 As shown. The preparation of the AC@NF negative electrode includes: mixing activated carbon, acetylene black, and polytetrafluoroethylene (PTFE) in a mass ratio of 8:1:1, adding anhydrous ethanol, grinding into a uniform slurry, coating onto pretreated nickel foam, vacuum drying for 6 hours, and pressing into a sheet at 10 MPa for 1 minute; the preparation of the PVA / KOH gel electrolyte includes: dissolving 4 g of PVA in 40 mL of deionized water, mixing with 20 mL of 2M KOH solution, stirring at 85°C for 30 minutes, and allowing to stand at room temperature for 24 hours.

[0068] according to Figure 12 It can be seen that this asymmetric supercapacitor exhibits good capacitance characteristics within the 0-1.8V potential window.

[0069] Connecting the asymmetric supercapacitor to an LED light panel with an FDU pattern results in: Figure 13 As shown.

[0070] according to Figure 13 As can be seen, the assembled soft-pack device can successfully light up a 3V FDU pattern LED light board, proving its practical application potential.

[0071] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0072] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application 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 therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A supercapacitor working electrode characterized by, Include: Conductive substrate; and An electrode active layer is grown in situ on the surface of the conductive substrate. The electrode active layer comprises an inorganic metal oxide nanocrystalline film, which is a continuous conductive structure formed by interconnecting single chiral inorganic metal oxide nanocrystals.

2. The supercapacitor working electrode of claim 1, characterized by, The chiral inorganic metal oxide nanocrystals are one or more of the following: L / D-chiral cobalt tetroxide nanocrystals, L / D-chiral nickel oxide nanocrystals, L / D-chiral ferric oxide nanocrystals, L / D-chiral manganese oxide nanocrystals, and L / D-chiral copper oxide nanocrystals.

3. The working electrode of the supercapacitor according to claim 1, characterized in that, The conductive substrate comprises fluorine-doped tin oxide conductive glass, nickel foam, and carbon cloth.

4. A method for preparing the working electrode of a supercapacitor according to any one of claims 1 to 3, characterized in that, Includes the following steps: A chiral metal hydroxide precursor film was prepared in situ grown on the surface of a conductive substrate by immersing the surface of the conductive substrate in a mixed aqueous solution containing a metal ion source compound, a chiral molecule and a pH adjuster. The chiral metal hydroxide precursor film is calcined in an oxygen atmosphere at 350-550°C for 1-6 hours to obtain the working electrode of the supercapacitor.

5. The preparation method according to claim 4, characterized in that, The chiral molecule is selected from one or more of L-threonine, D-threonine, L-proline, and D-proline.

6. The preparation method according to claim 4, characterized in that, The molar ratio of the metal ion source compound to the chiral molecule is 1:(1.5~2).

7. The preparation method according to claim 4, characterized in that, The pH adjuster contains urea and ammonia.

8. The preparation method according to claim 4, characterized in that, The hydrothermal reaction temperature of the hydrothermal method is 80~150℃, and the time is 10~18 hours.

9. A symmetrical supercapacitor, comprising a working electrode, a counter electrode, a reference electrode, and an electrolyte, characterized in that, The working electrode is the working electrode of the supercapacitor according to any one of claims 1 to 3.

10. An asymmetric supercapacitor comprising a positive electrode, a negative electrode, a separator, and a gel electrolyte, characterized in that the positive electrode is the working electrode of the supercapacitor according to any one of claims 1 to 3.

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