CdS-nico-ldh composite material, preparation method and application thereof

Abstract

The application relates to the technical field of composite materials, in particular to a CdS-NiCo-LDH composite material and a preparation method and application thereof. In the application, NiCo-LDH is obtained through a hydrothermal reaction, then CdS nanodots are introduced into the interlayer of the NiCo-LDH through an electrochemical reaction and in-situ sulfuration, so that the interlayer spacing is increased, the transportation of OH- is facilitated, the conductivity of the CdS nanodots is improved, the electron migration is facilitated, and the electrochemical reaction active sites are increased. Meanwhile, the in-situ synthesis method not only avoids the adverse influence of secondary growth, but also reduces the volume expansion of the NiCo-LDH in the redox reaction process.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to CdS-NiCo-LDH composite materials, their preparation methods, and applications. Background Technology

[0002] The non-renewable nature of fossil fuels and the increasingly serious environmental problems have prompted greater attention to sustainable energy conversion and storage technologies. Supercapacitors, due to their long cycle life and high output power, are widely used in applications requiring high power output. However, their relatively limited energy density has become a key obstacle to large-scale commercial application. To overcome this technological bottleneck, the development of advanced electrode materials with efficient electron / ion transport capabilities has become a key research focus.

[0003] Layered double hydroxides (LDHs), a special type of layered material, consist of several positively charged layers and anions with balanced charges in between. They possess advantages such as easily changeable composition, easily tunable structure, and ease of functionalization through combination with other materials, making them a focus of attention in the field of supercapacitors. Despite their promising properties, LDHs face two major limitations in energy storage applications: poor conductivity and a limited number of active sites. Summary of the Invention

[0004] Based on this, the present invention provides CdS-NiCo-LDH composite materials, their preparation methods and applications, thereby solving at least one problem in the prior art.

[0005] In a first aspect, the present invention provides a method for preparing a CdS-NiCo-LDH composite material, comprising the following steps:

[0006] Soluble nickel salt, soluble cobalt salt, ammonium fluoride and water are mixed to obtain solution A;

[0007] Mix urea and water to obtain solution B;

[0008] Mix the above solutions A and B to obtain solution C;

[0009] The support and the above C solution were placed in a reaction vessel and subjected to a hydrothermal reaction at 90℃-160℃ to obtain a support loaded with NiCo-LDH.

[0010] Using the aforementioned NiCo-LDH-loaded support as an electrode, placed in a soluble cadmium salt solution, and applying a voltage to the electrode, Cd is formed. 2+ -NiCo-LDH;

[0011] The above Cd 2+ -NiCo-LDH was immersed in a sulfide solution to obtain a CdS-NiCo-LDH composite material.

[0012] In this invention, NiCo-LDH is first obtained through a hydrothermal reaction. Then, CdS nanodots are introduced into the NiCo-LDH interlayer through electrochemical reaction and in-situ sulfidation, increasing the interlayer spacing and facilitating OH oxidation. - The construction of CdS nanodots improves electron conductivity, facilitates electron migration, and increases the number of electrochemical reaction active sites. Furthermore, the in-situ synthesis method not only avoids the adverse effects of secondary growth but also reduces the volume expansion of NiCo-LDH during redox reactions.

[0013] In some optional embodiments, the soluble nickel salt is nickel acetate, nickel nitrate, nickel chloride, or nickel sulfate, and the soluble cobalt salt is cobalt acetate, cobalt nitrate, cobalt chloride, or cobalt sulfate. Preferably, the soluble nickel salt is nickel chloride, and the soluble cobalt salt is cobalt chloride.

[0014] In some optional embodiments, the molar ratio of the soluble cobalt salt, soluble nickel salt, ammonium fluoride, and urea is 1:(3-6):(12-16):(19-30). Preferably, the molar ratio of the soluble cobalt salt, soluble nickel salt, ammonium fluoride, and urea is 1:3:12:19.2.

[0015] In some alternative embodiments, the carrier is nickel foam, carbon cloth, or graphite plate.

[0016] In some alternative embodiments, the hydrothermal reaction is carried out at 120°C.

[0017] In some optional embodiments, the soluble cadmium salt solution is a cadmium acetate solution, a cadmium nitrate solution, a cadmium chloride solution, or a cadmium sulfate solution. Preferably, the soluble cadmium salt solution is a cadmium chloride solution.

[0018] In some optional embodiments, the concentration of the soluble cadmium salt solution is 0.1-1.5 M. Preferably, the concentration of the soluble cadmium salt solution is 0.5 M.

[0019] In some alternative embodiments, the applied voltage refers to a voltage range of 0-1V with a voltage of 20mV s. -1 The scanning speed is 2-16 cycles. Preferably, the applied voltage refers to a voltage range of 0-1V with a frequency of 20mV / s. -1 The scanning speed cycles 8 times.

[0020] In some optional embodiments, the sulfide solution is a sodium sulfide solution or a potassium sulfide solution. Preferably, the sulfide solution is a sodium sulfide solution.

[0021] In some optional embodiments, the concentration of the sulfide solution is 0.3-0.5M.

[0022] In some optional embodiments, the temperature of the sulfide solution is 0-20°C. Preferably, the temperature of the sulfide solution is 5°C.

[0023] Secondly, the present invention provides a CdS-NiCo-LDH composite material, which is obtained by the above-mentioned preparation method of the CdS-NiCo-LDH composite material.

[0024] Thirdly, the present invention provides the application of the above-mentioned CdS-NiCo-LDH composite material in supercapacitors.

[0025] Fourthly, the present invention provides a supercapacitor comprising the aforementioned CdS-NiCo-LDH composite material.

[0026] Due to the adoption of the above technical solutions, the embodiments of the present invention have at least the following beneficial effects: For the first time, CdS nanodots are introduced into NiCo-LDH, synergistically combining the high conductivity of sulfides with the fast ion transport rate of LDH, endowing the CdS-NiCo-LDH composite material with excellent performance; when the CdS-NiCo-LDH composite material is used as an electrode, its performance at 1 A g... -1 It can exhibit 2637 F g at current density -1 The specific capacitance performance. Attached Figure Description

[0027] Figure 1 The graph shows the variation of electrode specific capacitance of 0.1M-8-CdS-NiCo-LDH, 0.3M-8-CdS-NiCo-LDH, 0.5M-8-CdS-NiCo-LDH, 1M-8-CdS-NiCo-LDH, and 1.5M-8-CdS-NiCo-LDH under different current densities in the embodiments of the present invention.

[0028] Figure 2 The graph shows the variation of electrode specific capacitance of 0.5M-2-CdS-NiCo-LDH, 0.5M-4-CdS-NiCo-LDH, 0.5M-8-CdS-NiCo-LDH, 0.5M-12-CdS-NiCo-LDH, and 0.5M-16-CdS-NiCo-LDH under different current densities in the embodiments of the present invention.

[0029] Figure 3 In the embodiments of the present invention, NiCo-LDH and Cd 2+ XRD patterns of 0.5M-8-CdS-NiCo-LDH and 0.5M-8-CdS-NiCo-LDH.

[0030] Figure 4 for Figure 3A magnified view of a portion of the image.

[0031] Figure 5 In the embodiments of the present invention, NiCo-LDH and Cd 2+ XPS characteristics of 0.5M-8-CdS-NiCo-LDH and 0.5M-8-CdS-NiCo-LDH.

[0032] Figure 6 The images shown are SEM and HR-TEM images of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH in the embodiments of the present invention.

[0033] Figure 7 The images show the EDS diagrams of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH in the embodiments of the present invention.

[0034] Figure 8 The cyclic voltammetry curves of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH in the embodiments of the present invention are shown.

[0035] Figure 9 The Nyquist plots for NiCo-LDH and 0.5M-8-CdS-NiCo-LDH are shown in the embodiments of the present invention.

[0036] Figure 10 The graph shows the variation of electrode specific capacitance of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH under different current densities in the embodiments of the present invention.

[0037] Figure 11 The graph shows the cycling performance of the electrodes of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH after 5000 cycles in the embodiments of the present invention.

[0038] Figure 12 The diagram shows the capacitance current (IDL) of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH at different scan rates at 0.3V in the embodiments of the present invention.

[0039] Figure 13 In this embodiment of the invention, NiCo-LDH and 0.5M-8-CdS-NiCo-LDH were loaded with 1 mg cm⁻¹ -2 Tafeldo at that time.

[0040] Figure 14 This is a schematic diagram of the structure of the supercapacitor in an embodiment of the present invention.

[0041] Figure 15 In this embodiment of the invention, 0.5M-8-CdS-NiCo-LDH and AC electrodes were used at 10 mV s. -1Electrode CV curve at time.

[0042] Figure 16 In this embodiment of the invention, CdS-NiCo-LDH / / AC operates at 10-100 mV s. -1 CV curves at different scan rates within the range.

[0043] Figure 17 The specific capacitance diagram of CdS-NiCo-LDH / / AC under different current densities is shown in the embodiment of the present invention.

[0044] Figure 18 This is a diagram showing the optimal energy density of CdS-NiCo-LDH / / AC under different power densities in the embodiments of the present invention.

[0045] Figure 19 This is a diagram showing the cycling performance of the CdS-NiCo-LDH / / AC device in this embodiment of the invention at 3500 cycles. Detailed Implementation

[0046] The following will provide a clear and complete description of the concept and technical effects of the present invention, so as to fully explain the purpose, solution and effects of the present invention.

[0047] Example 1

[0048] The CdS-NiCo-LDH composite material was prepared according to the following steps:

[0049] (1) Preparation of NiCo-LDH

[0050] NiCl₂•6H₂O (0.45 mmol), CoCl₃•6H₂O (0.15 mmol), and NH₄F (1.8 mmol) were dissolved in 30 mL of deionized water and stirred at room temperature for 10 minutes to obtain solution A. Urea (2.88 mmol) was then dissolved in 30 mL of deionized water and stirred at room temperature for 10 minutes to obtain solution B. Solutions A and B were then mixed and stirred for 10 minutes to obtain solution C. Solution C was transferred to a 100 mL reaction vessel, and a piece of nickel foam (1 × 3 cm) was placed inside. 2 The product was placed in the solution and reacted at 120°C for 5 hours. The product was collected and dried at 60°C for 12 hours to obtain nickel foam-supported NiCo-LDH.

[0051] (2) Cd 2+ Preparation of NiCo-LDH

[0052] Using a DH7000D electrochemical workstation, with NiCo-LDH-loaded nickel foam as the working electrode, an Hg / HgO electrode as the reference electrode, and a platinum mesh electrode as the counter electrode, Cd220 was carried out in a three-electrode electrochemical system. 2+ Intercalation. The cadmium source was selected as a 0.1M CdCl2 solution. Intercalation was performed at 20 mV s within a voltage range of 0-1V. -1 The scanning speed was cycled 8 times, the product was washed with deionized water and dried in a vacuum drying oven at 60°C for 12 hours to obtain nickel foam-loaded Cd. 2+ -NiCo-LDH.

[0053] (3) Preparation of CdS-NiCo-LDH

[0054] Add 1 g of Na₂S•9H₂O to 40 mL of deionized water and stir for 10 minutes to obtain a sodium sulfide solution. Then, at 5 °C, Cd-supported nickel foam is... 2+ NiCo-LDH was immersed in sodium sulfide solution for 1 hour. The resulting product was washed with ethanol and dried in a vacuum drying oven at 60°C for 12 hours to obtain the CdS-NiCo-LDH composite material.

[0055] In this embodiment, the concentration of the CdCl2 solution was 0.1M, the number of cycles was 8, and the final product CdS-NiCo-LDH composite material was labeled as 0.1M-8-CdS-NiCo-LDH.

[0056] Example 2

[0057] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.3M, and the final product CdS-NiCo-LDH composite material is labeled as 0.3M-8-CdS-NiCo-LDH.

[0058] Example 3

[0059] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.5M, and the final product CdS-NiCo-LDH composite material is labeled as 0.5M-8-CdS-NiCo-LDH.

[0060] Example 4

[0061] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 1M, and the final product CdS-NiCo-LDH composite material is labeled as 1M-8-CdS-NiCo-LDH.

[0062] Example 5

[0063] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 1.5M, and the final product CdS-NiCo-LDH composite material is labeled as 1.5M-8-CdS-NiCo-LDH.

[0064] Example 6

[0065] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.5M, the number of cycles is replaced with 2, and the final product CdS-NiCo-LDH composite material is labeled as 0.5M-2-CdS-NiCo-LDH.

[0066] Example 7

[0067] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.5M, the number of cycles is replaced with 4, and the final product CdS-NiCo-LDH composite material is labeled as 0.5M-4-CdS-NiCo-LDH.

[0068] Example 8

[0069] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.5M, the number of cycles is replaced with 12, and the final product CdS-NiCo-LDH composite material is labeled as 0.5M-12-CdS-NiCo-LDH.

[0070] Example 9

[0071] This embodiment is basically the same as Example 1, except that the concentration of the CdCl2 solution is replaced with 0.5M, the number of cycles is replaced with 16, and the final product CdS-NiCo-LDH composite material is labeled as 0.5M-16-CdS-NiCo-LDH.

[0072] Electrochemical properties of 0.1M-8-CdS-NiCo-LDH, 0.3M-8-CdS-NiCo-LDH, 0.5M-8-CdS-NiCo-LDH, 1M-8-CdS-NiCo-LDH, and 1.5M-8-CdS-NiCo-LDH were tested, and the results are as follows: Figure 1 As shown, the CdS-NiCo-LDH composite material exhibits the highest specific capacitance when the concentration of the CdCl2 solution is 0.5 M.

[0073] Electrochemical properties of 0.5M-2-CdS-NiCo-LDH, 0.5M-4-CdS-NiCo-LDH, 0.5M-8-CdS-NiCo-LDH, 0.5M-12-CdS-NiCo-LDH, and 0.5M-16-CdS-NiCo-LDH were tested, and the results are as follows: Figure 2 As shown in the image, a higher CdS content is not necessarily better, although CdS nanodots can act as OH groups. - CdS is an active center, but excessive CdS can disrupt the integrity of the LDH lattice, thus affecting the material's performance.

[0074] NiCo-LDH and Cd were analyzed using X-ray diffraction (Cu Kα-ray). 2+ The crystal structures of -NiCo-LDH and 0.5M-8-CdS-NiCo-LDH were determined, with a scan rate of 6° / min and a scan angle range of 10°-80°. The results are as follows: Figure 3 As shown, the number of peaks among the samples is basically consistent, indicating that the material preparation process did not significantly alter the composition. Based on the comparison with the PDF-89-460 card, it is evident that the main component of this material is NiCo-LDH. After in-situ sulfidation, the formation of CdS nanodots further expands the interlayer distance, which can be seen from the shift of the characteristic peaks towards smaller angles. Figure 4 The widened interlayer spacing is beneficial for OH during charging / discharging. - Ions shuttle between the layers of brucite to achieve high-rate performance.

[0075] Observation of NiCo-LDH and Cd by X-ray photoelectron spectroscopy (XPS) 2+ The changes in elemental valence state, composition, and electronic structure of -NiCo-LDH and 0.5M-8-CdS-NiCo-LDH are shown in the following results. Figure 5 As shown. After fitting the Ni 2P, Co 2P, and O1s data from the XPS test data, it can be found that 0.5M-8-CdS-NiCo-LDH and Cd 2+ The high degree of similarity between -NiCo-LDH and NiCo-LDH indicates that the original structure and properties of NiCo-LDH were not significantly damaged during the material preparation process, which corresponds to the XRD test results. 2+ After low-temperature sulfidation, the diffraction peaks of 0.5M-8-CdS-NiCo-LDH shift towards lower electron binding energies, indicating that Cd... 2+ It was reduced. The O 1s peak after CdS insertion into NiCo-LDH shifted to a lower binding energy, indicating an increase in the electron density around the O atom.

[0076] The microstructure and elemental distribution of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH were analyzed using scanning electron microscopy (Nova NaNoSEM450), transmission electron microscopy (FEI Talos F200X), and high-resolution electron microscopy (HRTEM). The state of each component on the surface of NiCo-LDH and 0.5M-8-CdS-NiCo-LDH was analyzed using XPS (Axis Ultra DLD).

[0077] Figure 6 Images a and b in the figure are SEM images of NiCo-LDH. As can be seen, dense nanosheets grow on a typical rod-like structure. This structure serves as a growth scaffold for NiCoLDH, effectively preventing aggregation, promoting efficient ion / electron transport, and reducing stress concentration during charging and discharging. Figure 6 Images d and e in the image are scanning electron microscope (SEM) images of 0.5M-8-CdS-NiCo-LDH. It can be seen that the nanostructure of 0.5M-8-CdS-NiCo-LDH remains unchanged compared to NiCoLDH, indicating that the introduction of CdS nanodots did not disrupt the morphology of NiCo-LDH. However, the differences between NiCo-LDH and 0.5M-8-CdS-NiCo-LDH are still clearly visible; NiCo-LDH has a smooth surface, while 0.5M-8-CdS-NiCo-LDH has a rough surface. The particles present in the interstitial spaces on the NiCo-LDH surface are CdS nanoparticles. Their introduction increases conductivity and expands the interlayer spacing, which is beneficial for improving related electrochemical performance. Figure 6 In the image, c is the HR-TEM image of NiCo-LDH. Figure 6 f in the image is an HR-TEM image of 0.5M-8-CdS-NiCo-LDH. It can be seen that the interlayer spacing of NiCo-LDH is 0.216 nm, while that of 0.5M-8-CdS-NiCo-LDH is 0.232 nm. The introduction of CdS nanodots successfully improved conductivity while simultaneously increasing the interlayer spacing.

[0078] Figure 7 In the figure, g and h are the energy dispersive X-ray spectra (EDS) of NiCo-LDH. Figure 7 In the diagram, i, j, k, and l represent the energy-dispersive X-ray spectra (EDS) of 0.5M-8-CdS-NiCo-LDH. It can be seen that Ni, Co, S, and Cd elements are uniformly distributed within the LDH range.

[0079] On a DH7000D electrochemical workstation, using 0.5M 8-CdS-NiCo-LDH as the working electrode, a carbon rod as the counter electrode, and Hg / HgO as the reference electrode, the electrochemical performance of the electrodes was evaluated in 1M KOH electrolyte (pH=14). The specific capacitance was calculated using the following equation:

[0080] Cs=(I·Δt) / (m·ΔV),

[0081] Where I is the discharge current (A), Δt is the discharge time (s), ΔV is the potential range (V), and m is the mass of the active material used (g).

[0082] For comparison, the electrochemical performance contribution of the NiCo-LDH sample was also measured and calculated.

[0083] First, cyclic voltammetry tests were performed on the samples at the same scan rate to explore the effect of interlayer nanodots on current and capacitance responses, such as... Figure 8 As shown, at 10mV s -1 In this case, it is clear that the cyclic voltammetry curve of 0.5M-8-CdS-NiCo-LDH is much larger than that of NiCo-LDH.

[0084] Cyclic voltammetry curves were tested at different scan rates within the same potential window (0-0.8V), as follows: Figure 9 As shown, the range of the cyclic voltammetry curve increases with increasing scan rate, but the profile still exhibits the same shape, indicating its good rate performance. Electrochemical impedance spectroscopy (EIS) is used to study the charge transfer capability of all electrodes and OH-. - Ion diffusion. Analysis revealed that the impedance of 0.5M-8-CdS-NiCo-LDH was lower than that of NiCo-LDH. This is because the introduction of interlayer CdS nanodots resulted in lower confinement of ion / electron transport.

[0085] The capacitance performance of 0.5M-8-CdS-NiCo-LDH can be calculated in detail using galvanostatic charge-discharge (GCD) curves and compared with that of NiCo-LDH electrode material. Figure 10 As shown, in 1A g -1 At a current density of 2637 F g, the specific capacitance of 0.5M-8-CdS-NiCo-LDH is 2637 F g. -1 ) is the NiCo-LDH specific capacitance (765 F g) -1 The specific capacitance of the sample decreased as the current density increased, but the capacitance retention rate of 0.5M-8-CdS-NiCo-LDH (75%) was still better than that of NiCo-LDH (58%).

[0086] like Figure 11 As shown, 0.5M-8-CdS-NiCo-LDH at 10 A g −1 It also exhibits high cycling activity, with a capacity retention of 80.9% after 5000 cycles, which is significantly higher than the 40% capacity retention of NiCo-LDH under the same test conditions.

[0087] like Figure 12 As shown, 0.5M-8-CdS-NiCo-LDH exhibits a higher electrochemical active area than NiCo-LDH, further demonstrating the significant contribution of cadmium sulfide modification and intercalation to improving the efficiency of LDH supercapacitors.

[0088] like Figure 13 As shown, the Tafel slope of 0.5M-8-CdS-NiCo-LDH (56 mV Dec) -1 The Tafel slope (478 mV Dec) is much lower than that of NiCo-LDH. -1 This further explains the enhanced redox kinetics. This is because the interlayer NDs increase the activity of the inert inner surface of the LDH, reduce the overpotential, and accelerate the redox process.

[0089] A hybrid supercapacitor is constructed using NiCo-LDH (positive electrode material), AC (negative electrode material, activated carbon), and 1M KOH (electrolyte), denoted as NiCo-LDH / / AC; wherein the mass loading ratio of NiCo-LDH to AC is matched at 1:9. Figure 14 As shown, a hybrid supercapacitor is constructed using 0.5M-8-CdS-NiCo-LDH (positive electrode material), AC (negative electrode material, activated carbon), and 1M KOH (electrolyte), denoted as CdS-NiCo-LDH / / AC; wherein the mass loading ratio of 0.5M-8-CdS-NiCo-LDH to AC is matched at 1:9. The energy density (E) and power density (P) of the device are calculated using the following integral formula:

[0090] E=(I / m)∫V(t)dt

[0091] P=E / Δt

[0092] Where I is the discharge current (A), m is the total mass of the positive and negative electrode materials (g), ∫V(t)dt is the area under the constant current discharge curve (V·s-1), and Δt is the discharge time (s).

[0093] like Figure 15 As shown, the 0.5M-8-CdS-NiCo-LDH and AC electrode exhibit a stable and compatible voltage window, demonstrating the feasibility of the assembly. At 100 mV s -1Under stable operating voltage conditions, the negative electrode exhibits a potential window of (-1V to 0V), and the positive electrode exhibits a potential window of (0V to 0.5V), indicating that the operating voltage of the assembled device can be set to 1.5V. The mass load ratio of the positive and negative electrodes can be calculated to be 0.11 using relevant formulas.

[0094] Figure 16 The results showed that CdS-NiCo-LDH / / AC was in the range of 10-100 mV s. -1 CV curves at different scan rates within the range. The formation of the redox peak (0-1.5 V) indicates that the device effectively combines the advantages of Faraday mechanism and EDLC behavior.

[0095] At the same time, such as Figure 17 As shown, with increasing scan rate, the shape of the CV curve changes very little within the same voltage window, indicating that the device (CdS-NiCo-LDH / / AC) exhibits good electrochemical reversibility. The specific capacitance of the device decreases with increasing current density, especially at 1 A g. -1 At that time, the specific capacitance was 85 F g. -1 ; while in 5A g -1 At that time, the specific capacitance was 60 Fg -1 When the current density increases by 5 times, the capacitance retention of CdS-NiCo-LDH / / AC is 70%.

[0096] like Figure 18 As shown, at a power density of 1605 W kg -1 At that time, the optimal energy density of the device was 53.23 Wh / kg. -1 Even if the power density increases to 39.04 kW kg -1 It can also maintain 28.18 Wh kg -1 .

[0097] Through 10 Ag -1 The stability of the electrode material was investigated by performing 3500 charge / discharge cycles. The results are as follows: Figure 19 As shown, the device sample retained 63% of its initial capacity after 3500 consecutive cycles.

[0098] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any embodiment that achieves the technical effects of the present invention by the same or equivalent means should fall within the protection scope of the present invention. Within the protection scope of the present invention, various modifications and variations can be made to the technical solutions and / or implementation methods.

Claims

1. A method for preparing a CdS-NiCo-LDH composite material, wherein the CdS-NiCo-LDH composite material is used to prepare a supercapacitor, characterized in that, The preparation method of the CdS-NiCo-LDH composite material includes the following steps: Soluble nickel salt, soluble cobalt salt, ammonium fluoride and water are mixed to obtain solution A; Mix urea and water to obtain solution B; Solution A and solution B are mixed to obtain solution C; The support and the C solution were placed in a reaction vessel and subjected to a hydrothermal reaction at 90℃-160℃ to obtain a support loaded with NiCo-LDH. The NiCo-LDH-loaded support was used as an electrode and placed in a soluble cadmium salt solution. A voltage was applied to the electrode to form Cd. 2+ -NiCo-LDH; The Cd 2+ -NiCo-LDH was immersed in a sulfide solution to obtain a CdS-NiCo-LDH composite material; The molar ratio of the soluble cobalt salt, soluble nickel salt, ammonium fluoride, and urea is 1:(3-6):(12-16):(19-30). The concentration of the soluble cadmium salt solution is 0.1-1.5M; The sulfide solution is a sodium sulfide solution or a potassium sulfide solution; the concentration of the sulfide solution is 0.3-0.5M; The applied voltage refers to a voltage range of 0-1V with a voltage of 20mV / s. -1 The scanning speed cycles 2-16 times.

2. The method according to claim 1, characterized in that, The soluble nickel salt is nickel acetate, nickel nitrate, nickel chloride, or nickel sulfate, and the soluble cobalt salt is cobalt acetate, cobalt nitrate, cobalt chloride, or cobalt sulfate.

3. The method according to claim 1, characterized in that, The soluble cadmium salt solution is a cadmium acetate solution, a cadmium nitrate solution, a cadmium chloride solution, or a cadmium sulfate solution.

4. A CdS-NiCo-LDH composite material, characterized in that, It is obtained by the preparation method of the CdS-NiCo-LDH composite material according to any one of claims 1-3.

5. A supercapacitor, characterized in that, Including the CdS-NiCo-LDH composite material as described in claim 4.

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