F-NiCoS-OH composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of supercapacitors, in particular to an F-NiCoS-OH composite material and a preparation method and application thereof, and aims to solve the problems that in the prior art, the regulation and control capacity of a single strategy is limited, and collaborative optimization of the electronic structure, interface property and microstructure of a material cannot be achieved. The preparation method comprises the following steps: dissolving potassium ferricyanide in water, and carrying out a co-precipitation reaction to obtain an F-NiCo-PBA precursor; s2, mixing the F-NiCo-PBA precursor with a sulfur source, and carrying out a hydrothermal vulcanization reaction, so as to obtain F-NiCoS; and S3, the F-NiCoS is subjected to alkali treatment, and the F-NiCoS-OH is obtained. The PBA is used as a precursor, synthesis is performed through a coprecipitation-vulcanization-alkali treatment three-step method, the process is simple, conditions are mild, repeatability is good, and large-scale production is easy. Meanwhile, through structural characterization and an electrochemical test, the F-NiCoS-OH electrode material has excellent rate capability and ultra-long cycle life.

Description

Technical Field

[0001] This invention relates to the field of supercapacitor technology, and in particular to an F-NiCoS-OH composite material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of continuously growing energy demand and rapid development of energy conversion technologies, the advancement of electrochemical energy storage (EES) technology has become an urgent priority. The inherent intermittency and instability of renewable energy sources such as solar and wind power pose significant challenges to reliable energy storage and supply. Furthermore, the rapid development of portable electronic devices and electric vehicles places higher demands on high-performance EES devices. Supercapacitors, as an innovative EES system, possess unique advantages such as ultra-fast charging and discharging, high power density, and ultra-long cycle life (up to tens of thousands of cycles), showing broad application prospects in portable electronic devices, new energy vehicles, and smart grids. However, electrode materials are the core components determining the performance of supercapacitors. The superior performance of supercapacitors is highly dependent on electrode materials. Ideal electrode materials should possess excellent conductivity, high porosity, high theoretical capacitance, abundant and accessible electrochemical active sites, and short ion diffusion paths. Therefore, developing high-performance supercapacitor electrode materials is crucial for improving the energy density of supercapacitors and expanding their application range.

[0003] In recent years, transition metal sulfides (TMSs) have become strong candidates for supercapacitor electrode materials due to their unique physicochemical properties. First, TMSs have abundant redox active sites, resulting in high theoretical specific capacity. For example, nickel and cobalt ions in nickel-cobalt sulfides can undergo multi-electron redox reactions to achieve the storage of a large amount of charge. Second, TMSs generally have better conductivity than their oxide counterparts, which is conducive to rapid charge transfer and thus improves electrochemical performance. In addition, sulfur has lower electronegativity than oxygen in oxides, which helps to improve the flexibility and stability of the material. However, there are still some problems to be solved in the practical application of TMSs: (1) During charging and discharging, TMSs are prone to irreversible structural changes, such as lattice collapse, which is mainly caused by the dissolution of sulfur ions in the electrolyte. This structural instability leads to rapid capacity decay and seriously affects the cycle life of the electrode material; (2) The ion diffusion kinetics of TMSs at high current densities often deteriorate, which limits their application in high-power demand scenarios.

[0004] To overcome the aforementioned limitations, existing technologies typically employ a single modification strategy, such as heteroatom doping, constructing heterostructures, or designing porous structures, to control the morphology, phase composition, and electronic structure of TMSs, thereby improving their electrochemical performance. Heteroatom doping involves introducing specific atoms into the TMS lattice, altering its electronic structure, modulating the Fermi level, and thus affecting its electrical properties. As typical point defects, heteroatoms can optimize the electron cloud distribution at active sites, enhancing their adsorption capacity for electrolyte ions and improving the redox reaction kinetics of electrode materials. Heterostructures can generate endogenous electric fields at interfaces, effectively driving the directional migration of charge carriers and accelerating charge transfer within the electrode material. By introducing line and surface defects, heterostructures can further modulate surface properties, providing additional active sites or improving the accessibility of existing active sites. For example, compared to monometallic sulfides, bimetallic sulfides typically exhibit significantly improved electrochemical activity and stability, which can be attributed to the mixed valence states and significant synergistic effects between the two metals, promoting abundant redox reactions and enhancing charge storage performance. The design of porous structures involves constructing mesoporous or macroporous structures to provide ion transport channels and active sites.

[0005] Although defect engineering is effective in practice, doping with a single heteroatom is not conducive to the stability of the overall structure and limits the optimization of ion transport paths. The heterojunction interface formed by constructing heterostructures has poor stability, which also limits the improvement of the intrinsic conductivity of the material. The design of porous structures may collapse during long-term cycling, resulting in limited controllability of a single strategy and making it impossible to achieve synergistic optimization of the material's electronic structure, interface properties and microstructure. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide an F-NiCoS-OH composite material, its preparation method, and its applications. Existing technologies have limited control capabilities with single strategies; relying solely on heteroatom doping or heterostructure construction cannot achieve synergistic optimization of the material's electronic structure, interface properties, and microstructure. This invention effectively combines heteroatom doping and heterostructure construction, using PBA as a precursor, and employs a three-step method to simultaneously achieve precise control of F and O dual-element doping, heterostructure construction, and mesoporous structure, thereby optimizing the conductivity, number of active sites, and structural stability of the electrode material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a method for preparing F-NiCoS-OH composite material, comprising the following steps:

[0009] S1: Dissolve nickel salt, cobalt salt and fluorine source in water to obtain solution A, dissolve potassium ferricyanide in water to obtain solution B, mix solution A and solution B to carry out coprecipitation reaction to obtain F-NiCo-PBA precursor;

[0010] S2: Dissolve the F-NiCo-PBA precursor obtained in S1 in anhydrous ethanol to obtain solution C, dissolve the sulfur source in water to obtain solution D, mix solution C and solution D and carry out hydrothermal sulfidation reaction to obtain F-NiCoS;

[0011] S3: Mix the F-NiCoS obtained in S2 with an alkaline solution and perform alkaline treatment to obtain F-NiCoS-OH.

[0012] Furthermore, the molar ratio of nickel salt, cobalt salt, and fluorine source in solution A of S1 is 1:0.8-1.2:2.5-30.

[0013] Furthermore, the nickel salt is NiCl2·6H2O, the cobalt salt is CoCl2·6H2O, and the fluorine source is NaF.

[0014] Furthermore, the mass ratio of the F-NiCo-PBA precursor to the sulfur source in S2 is 1:1.8-2.2, and the sulfur source is thiourea.

[0015] Furthermore, the hydrothermal sulfidation reaction in S2 is carried out at a temperature of 150-180°C for 2-4 hours.

[0016] Furthermore, the alkaline solution in S3 is a KOH solution.

[0017] On the other hand, the present invention also provides an F-NiCoS-OH composite material prepared using the preparation method of the F-NiCoS-OH composite material as described above.

[0018] Furthermore, this invention also provides applications of F-NiCoS-OH composite materials in electrode materials, supercapacitors, portable electronic devices, and electric vehicles.

[0019] The beneficial effects of this invention are: compared with the prior art, the improvement of this invention lies in that...

[0020] 1. This invention uses PBA as a precursor and synthesizes the F-NiCoS-OH electrode material via a three-step method of co-precipitation-sulfidation-alkali treatment. The process is simple, the conditions are mild, the reproducibility is good, and it is easy to scale up for production. Furthermore, through structural characterization and electrochemical testing, the F-NiCoS-OH electrode material exhibits a specific capacitance as high as 680 F / g at a current density of 1 A / g; at a high current density of 10 A / g, the capacity retention rate still reaches 58.8%; and after 10,000 charge-discharge cycles, the capacity retention rate is as high as 95%, demonstrating excellent rate performance and ultra-long cycle life. This proves the enhanced electrical performance mechanism of the F-NiCoS-OH composite material prepared by the method of this invention, which is beneficial for the application of F-NiCoS-OH composite materials in the fields of electrode materials and supercapacitors.

[0021] 2. This invention prepares F-NiCoS-OH composite materials through a three-step method of co-precipitation-sulfidation-alkali treatment, which combines three strategies: F and O heteroatom doping (point defects), heterostructure construction (surface defects), and mesoporous structure engineering (bulk defects). This overcomes the shortcomings of existing TMSs electrode materials in terms of specific capacity, rate performance, and cycle stability, and provides an electrode material with a multi-dimensional synergistic enhancement effect. It realizes multi-scale control of electrode materials from the atomic level to the microstructure, and synergistically improves the comprehensive electrochemical performance of the material. Attached Figure Description

[0022] Figure 1 The following is a schematic diagram of the synthesis process of F-NiCoS-OH of the present invention, as well as its morphology and structural features: (a) is a schematic diagram of the synthesis process; (be) are scanning electron microscope (SEM) images of F-NiS, F-CoS, F-NiCoS and F-NiCoS-OH, respectively; (f) is a transmission electron microscope (TEM) image of F-NiCoS-OH; (g) is a high-resolution transmission electron microscope (HRTEM) image of F-NiCoS-OH; and (h) is an elemental distribution map of F-NiCoS-OH.

[0023] Figure 2 Crystal structure characterization of the present invention: (a) XRD pattern, (b) XPS total spectrum, (c) Ni, (d) Co, (e, f) high-resolution XPS spectra of S, (g) binding energy changes of F-NiS, F-CoS, F-NiCoS and F-NiCoS-OH, (h) peak area ratio, (i) atomic ratio.

[0024] Figure 3The electrochemical characterization results of this invention are as follows: (a) CV curve, (b) GCD curve, (c) rate performance, (d) Nyquist curve (the inset shows the fitted equivalent circuit), (e) scan rate versus current density graph, and (f) logi and logv relationships of NiCoS and F-NiCoS.

[0025] Figure 4 Electrochemical testing for this invention: (a) 1 mV s -1 (a) is the CV curve at 1 A / g, (b) is the GCD curve at 1 A / g, (c) is the Nyquist curve (the inset shows the fitted equivalent circuit), (d) is the GCD plot of F-NiCoS-OH at different current densities, (e) is the specific capacitance at different current densities, (f) is the relationship between scan rate and current density, (g) is the CV curve of F-NiCoS-OH at different scan rates, (h) is the relationship between logi and logv, and (i) is the CV curve of F-NiCoS-OH at 1-5 mV s. -1 Diffusion control and capacitance contribution during time.

[0026] Figure 5 Electrochemical stability tests for the present invention: (a) stability test of F-NiCoS-OH, (b) Nyquist curve of F-NiCoS-OH, (c) SEM image of F-NiCoS-OH after cycling stability test, (d) XRD pattern, (e) XPS spectrum, (f) high-resolution XPS spectrum of Ni, (g) Co, (h) S, and (i) peak area ratio.

[0027] Figure 6 Electrochemical performance characterization of the F-NiCoS-OH / / CNT of the present invention: (a) 10 mV s -1 CV curves of F-NiCoS-OH and CNT, (b) at 100 mV s -1 The CV plots for 1.0V to 1.45V are shown in (c), GCD plot, rate performance plot, Ragone plot, stability test plot, and Nyquist plot before and after 10,000 cycles.

[0028] Figure 7 This is a TEM image of F-NiCoS of the present invention.

[0029] Figure 8 This is a TEM image of F-NiCoS-OH of the present invention.

[0030] Figure 9 This is the EDS diagram of F-NiCoS-OH of the present invention.

[0031] Figure 10 The following are SEM images of NiCo-PBA and F-NiCo-PBA of the present invention: (a) is the SEM image of NiCo-PBA, and (b) is the SEM image of F-NiCo-PBA.

[0032] Figure 11 The XRD patterns of NiCo-PBA and F-NiCo-PBA of the present invention are shown.

[0033] Figure 12 The images show the FT-IR spectra of NiCo-PBA, F-NiPBA, F-CoPBA, and F-NiCo-PBA of the present invention.

[0034] Figure 13 The images are FT-IR spectra of F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH of the present invention.

[0035] Figure 14 The following are N2 adsorption-desorption isotherms and pore size distribution diagrams for F-NiS, F-CoS, F-NiCoS and F-NiCoS-OH of the present invention: (a) is the N2 adsorption-desorption isotherm, and (b) is the pore size distribution diagram.

[0036] Figure 15 This is a Zeta potential diagram of F-NiS, F-CoS, F-NiCoS and F-NiCoS-OH of the present invention.

[0037] Figure 16 The O1s high-resolution XPS spectra and peak area ratios of F-NiCoS and F-NiCoS-OH of the present invention are shown in (a) and (b) respectively.

[0038] Figure 17 The CV curves and GCD curves of NiCoS and F-NiCoS of the present invention are shown below: (a) is the CV curve of NiCoS, (b) is the CV curve of F-NiCoS, (c) is the GCD curve of NiCoS, and (d) is the GCD curve of F-NiCoS.

[0039] Figure 18 The Bode phase diagrams for NiCoS and F-NiCoS of the present invention are shown.

[0040] Figure 19 The CV curves of NiCoS and F-NiCoS of the present invention at different scan rates in the range of 0 to 0.1V are shown: (a) is the CV curve of NiCoS, and (b) is the CV curve of F-NiCoS.

[0041] Figure 20The CV curves of F-NiS and F-CoS of the present invention at different scan rates are shown: (a) is the CV curve of F-NiS, and (b) is the CV curve of F-CoS.

[0042] Figure 21 The Bode phase diagrams for F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH of the present invention are shown below.

[0043] Figure 22 The CV curves of F-NiS, F-CoS and F-NiCoS-OH of the present invention at different scan rates from 0 to 0.1V are shown: (a) is the CV curve of F-NiS, (b) is the CV curve of F-CoS and (c) is the CV curve of F-NiCoS-OH.

[0044] Figure 23 The high-resolution XPS spectrum of O1s of F-NiCoS-OH after electrochemical stability testing of this invention is shown.

[0045] Figure 24 The CV and GCD diagrams of the CNT of the present invention are shown in Figure 1: (a) is the CV diagram, and (b) is the GCD diagram.

[0046] Figure 25 This is a comparison of the Bode phase of the F-NiCoS-OH / / CNT device of the present invention before and after 10,000 cycles. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0048] Example 1:

[0049] See Figure 1 As shown in (a), this invention proposes a method for preparing F-NiCoS-OH composite materials. The F-NiCoS-OH composite material prepared by this method can be used as an F / O co-doped Ni-Co-S electrode material, applicable in fields such as supercapacitors, portable electronic devices, and electric vehicles, demonstrating good practical application potential and value. The specific preparation method of this F-NiCoS-OH composite material is as follows:

[0050] S1: Dissolve nickel salt, cobalt salt, and fluorine source in water to obtain solution A; dissolve potassium ferricyanide in water to obtain solution B; mix solution A and solution B for a co-precipitation reaction to obtain the F-NiCo-PBA precursor, specifically:

[0051] 0.3 mmol of NiCl2·6H2O (0.0713 g) and 0.3 mmol of CoCl2·6H2O (0.0714 g) were dissolved sequentially in 20 mL of deionized water, followed by the addition of 1.5 mmol of NaF (0.063 g) to obtain solution A. Separately, 0.4 mmol of K3[Fe(CN)6] (0.1317 g) was dissolved in 20 mL of deionized water to obtain solution B. Solutions A and B were thoroughly mixed and allowed to stand overnight at room temperature to allow coprecipitation. The reaction product was washed, centrifuged, and dried at 60 °C to obtain the F-doped nickel-cobalt Prussian blue analog: F-NiCo-PBA. The obtained F-NiCo-PBA was used as a precursor.

[0052] The reaction mechanism of the coprecipitation reaction: Nickel and cobalt ions coordinate with fluoride ions to form [CoF6]. 4- Or [NiF6] 4- Complex, introducing [Fe(CN)6] 3- After that, F - Replaced and transformed into Ni X [Fe(CN)6] or Co X [Fe(CN)6]. Due to F - The ionic radius is small and the electronegativity is high, and some F - They remain bound within the lattice of the Prussian blue analogue (PBA), forming F-NiCo-PBA nanoparticles.

[0053] S2: The F-NiCo-PBA precursor obtained in S1 is dissolved in anhydrous ethanol to obtain solution C. The sulfur source is dissolved in water to obtain solution D. Solutions C and D are mixed and subjected to a hydrothermal sulfidation reaction to obtain F-NiCoS. Specifically:

[0054] Take 30 mg of the F-NiCo-PBA precursor prepared in S1 and disperse it in 20 mL of anhydrous ethanol to obtain solution C. Separately, dissolve 60 mg of thiourea in 10 mL of deionized water to obtain solution D. After thoroughly mixing solutions C and D, transfer them to a 50 mL polytetrafluoroethylene-lined stainless steel reactor for hydrothermal vulcanization reaction at a temperature of 160 °C for 3 h. The reaction product is washed, centrifuged, and dried at 60 °C to obtain F-doped nickel-cobalt sulfide: F-NiCoS.

[0055] The hydrothermal sulfidation reaction mechanism: Using F-NiCo-PBA as a precursor and thiourea as a sulfur source, F-NiCoS is synthesized under hydrothermal conditions. At 160℃, thiourea hydrolyzes to release H2S, partially replacing [Fe(CN)6] in the PBA structure. 3-Transition metal sulfides (TMSs) are formed, and due to incomplete sulfidation, the PBA structure still exists in F-NiCoS.

[0056] S3: The F-NiCoS obtained in S2 is mixed with an alkaline solution and subjected to alkaline treatment to obtain F-NiCoS-OH, specifically:

[0057] The F-NiCoS prepared in S2 was subjected to alkali treatment. The F-NiCoS was placed in 20 mL of 0.1 mol / L KOH solution and left to stand overnight at room temperature. The reaction product after alkali treatment was washed, centrifuged and dried at 60 °C to obtain F and O co-doped Ni-Co-S electrode material: F-NiCoS-OH.

[0058] Reaction mechanism of alkali treatment: OH - It partially substitutes sulfur or [Fe(CN)6] under alkaline conditions. 3- Oxygen is introduced into the lattice to form doped structures or hydroxide species, while the mesopores based on PBA are precisely expanded by alkaline etching to construct a hierarchical porous structure.

[0059] This invention synthesizes F-NiCoS-OH composite material through a three-step method of co-precipitation, sulfidation, and alkali treatment. Co-precipitation and sulfidation achieve F doping and heterostructure construction, while subsequent alkali treatment introduces O atoms and constructs a mesoporous structure. The dual-ion doping, heterojunction, and mesoporous structure control the morphology and electronic structure of the material from point defects to bulk phase regulation, thus constructing a unique F-NiCoS-OH composite material.

[0060] Comparative example:

[0061] Using Example 1 as a basic example, this invention also provides a comparative example of Example 1, in which the alkali treatment in step S3 is omitted to reduce the impact of -OH on performance. Specifically: In order to clearly compare the effect of F doping on performance, this comparative example prepares an F-doped NiCo-PBA precursor according to steps S1 and S2 of Example 1 without adding NaF, and then uses the undoped NiCo-PBA precursor to prepare NiCoS.

[0062] Meanwhile, in this comparative example, a Co-doped F-Ni-PBA precursor (F-doped nickel Prussian blue analogue) and a Ni-doped F-Co-PBA precursor (F-doped cobalt Prussian blue analogue) were prepared according to steps S1 and S2 in Example 1, and F-NiS and F-CoS were prepared using the F-Ni-PBA precursor and F-Co-PBA precursor, respectively.

[0063] Based on the above Example 1 and Comparative Example, structural characterization analysis and comparison, and electrochemical performance characterization analysis and comparison were performed on the F-NiCoS-OH prepared in Example 1 and the NiCoS, F-NiS, and F-CoS prepared in the Comparative Example. Specifically:

[0064] First, regarding morphological and structural characteristics, a systematic study was conducted on F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH samples. (See reference...) Figure 1 As shown in (b), F-NiS exhibits a nanoparticle morphology with an average diameter of approximately 40 nanometers. (See also...) Figure 1 As shown in (c), F-CoS is mainly composed of nanocubes with an average particle size of approximately 190 nanometers. When a bimetallic component is introduced, refer to... Figure 1 (d) and Figure 7 As shown, F-NiCoS exhibits a nanoparticle morphology that, compared to F-NiS, shows more defined edges and a more uniform morphology, with an average particle size of approximately 50 nanometers. After alkali treatment, see [reference needed]. Figure 1 (e) and Figure 8 As shown, F-NiCoS-OH is mainly composed of nanoparticles and simultaneously observed nanosheet structures with an average diameter exceeding 250 nanometers. (See reference...) Figure 1 As shown in (f), high-resolution transmission electron microscopy (HRTEM) images further confirm the presence of the lamellar structure, which is likely due to oxygen incorporation into the F-NiCoS lattice under alkaline conditions. This combination of particles and lamellar structures can form a hierarchical porous network, providing a high specific surface area, reducing structural packing or agglomeration, ensuring sufficient electrolyte wetting, and improving the utilization efficiency of active sites. The synergistic effect between different structures can optimize electron / ion transport pathways, promote electrolyte penetration and rapid ion transport, reduce polarization, thereby maintaining electrochemical activity and stability.

[0065] See Figure 1 As shown in (g), the measured interplanar spacings of 0.202 nm and 0.254 nm correspond to the (220) and (210) crystal planes of NiS2, respectively, and the interplanar spacing of 0.238 nm corresponds to the (400) crystal plane of Co3S4, confirming the successful formation of the heterostructure. The heterostructure can trigger a redistribution of surface charge at the contact interface (from F-NiS to F-CoS), enhancing the accessibility of ions to active sites, lowering the activation energy barrier of reduction kinetics, and promoting surface redox reactions. Furthermore, see [reference needed]. Figure 1As shown in (g) of the HRTEM image of F-NiCoS-OH, distorted and displaced lattice structures were observed at the white lines, likely due to oxygen substitution for sulfur, inducing lattice distortion. Lattice distortion can increase energy storage density, optimize storage mechanisms, enhance the conductivity and stability of electrode materials, promote ion adsorption and diffusion, and improve pseudocapacitance. See also... Figure 1 (h) and Figure 9 As shown in the EDS analysis and corresponding elemental distribution diagram, Ni, Co, S, F, Na, K, and O elements are uniformly distributed in F-NiCoS-OH. The K element originates from K3[Fe(CN)6] and KOH, the O element may originate from water molecules in PBA or O atoms introduced during alkaline treatment, and the Na and F elements originate from NaF.

[0066] When using NaF as a regulator in the synthesis of Prussian blue analogues (PBA), due to F... - With its small ionic radius and high electronegativity, fluorine (F) atoms can penetrate the crystal lattice. F doping can alter the crystal structure, inducing lattice distortion and phase transitions, and can also influence nanostructures by changing the pore structure. Just as... Figure 1 (be) and Figure 10 As shown, compared with NiCo-PBA synthesized without NaF, F-NiCo-PBA synthesized with NaF exhibits more precise boundaries and significantly larger particle size. In the XRD patterns, both samples show typical PBA structures (JCPDS#73-0683). Figure 11 As shown, the diffraction peaks of F-NiCo-PBA are significantly narrower and more intense, indicating larger particle size, more regular shape, and higher crystallinity. Furthermore, the main diffraction peaks of F-NiCo-PBA shift to higher angles, indicating a decrease in interplanar spacing, which may be due to the introduction of F. Figure 12 As shown, in the FT-IR spectrum, the key characteristic peak of PBA is located at 2100 cm⁻¹. -1 The C≡N stretching vibration. Compared to F-CoPBA, the C≡N peak in other Ni-based PBA samples splits into two independent components, corresponding to FeII-C≡N-NiII and FeIII-C≡N-NiII, respectively. This phenomenon may be due to local structural distortion caused by high-density defects. Located at approximately 3400 cm⁻¹ -1 The broad peak can be attributed to the OH stretching vibrations of crystal water and adsorbed water. The increased intensity of this peak in the Ni-based PBA sample indicates a higher water content, further confirming the presence of the defect structure. (594 cm⁻¹) -1 and 1610cm -1 The peaks at 1100 cm⁻¹ correspond to the Fe-C bending vibration and the HOH bending vibration, respectively. It is noteworthy that in the F-doped sample, the peak at 1100 cm⁻¹... -1A new peak related to CF stretching vibrations appeared, confirming the successful incorporation of F. In summary, SEM images, XRD patterns, and FT-IR spectra all jointly confirm the incorporation of F. - Ions have been successfully incorporated into the crystal lattice. F doping enhances electrical conductivity, improves structural and chemical stability, and optimizes the energy storage mechanism by increasing active sites and modulating redox potential. Furthermore, the F content in F-NiCo-PBA (0.43%), F-NiCoS (0.42%), and F-NiCoS-OH (0.43%) is similar, indicating that sulfidation and alkali treatment have no effect on F doping.

[0067] Secondly, regarding crystal structure, XRD analysis was used to analyze the crystal structures of F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH. For example... Figure 2 As shown in (a), all four samples simultaneously exhibited the characteristic PBA structure (JCPDS#73-0683) and the sulfide phase. Specifically, the additional diffraction peaks in F-NiS are attributed to NiS2 (JCPDS#88-1709), while the diffraction peaks in F-CoS correspond to Co3S4 (JCPDS#73-1703) and CoS2 (JCPDS#89-1492). The aforementioned sulfide structures were observed in both F-NiCoS and F-NiCoS-OH. After alkali treatment, the PBA-related diffraction peaks in F-NiCoS-OH were significantly weakened, which can be attributed to the OH... - The role of ions. Literature reports indicate that immersing PBA in an alkaline solution generates the corresponding hydroxide. Subsequently, FT-IR spectroscopy is used to further characterize the chemical bonds in the sample. For example... Figure 13 As shown, 2100cm -1 The C≡N stretching vibration peak at 594 cm⁻¹ and the peak at 594 cm⁻¹ -1 The Fe-C bending vibration peak at the location confirmed the retention of the PBA structure in all samples, which is consistent with the XRD results. Figure 12 Compared to pure PBA samples, sulfide samples showed improvement at approximately 1400 cm⁻¹. -1 The appearance of a new peak, attributed to the C=S stretching vibration, confirms the successful conduct of the sulfidation reaction. After alkali treatment, the C=S signal in F-NiCoS-OH weakens, indicating some sulfur loss.

[0068] Furthermore, the pore structure of the samples was significantly affected by heterostructure and alkali treatment. For example... Figure 14 As shown in (a), the nitrogen adsorption / desorption isotherm exhibits a typical type IV curve with an H3-type hysteresis loop, indicating the presence of a mesoporous structure. Figure 14 As shown in (b) in the figure, the aperture distribution further confirms this.

[0069] Table 1 Structural characterization results of each sample

[0070] <![CDATA[Surface area (m 2 / g)]]> <![CDATA[Mesoporous area (m 2 / g)]]> Hole size (nm) F-NiS 409.9 132.9 19.4 F-CoS 10.5 10.8 11.1 F-NiCoS 491.8 222.7 18.4 F-NiCoS-OH 263.5 242.9 9.2

[0071] Furthermore, referring to Table 1 above, among all samples, F-NiCoS has the largest specific surface area, reaching 491.8 m². 2 / g, confirming that F-NiS(409.9m 2 / g) and F-CoS(10.5m 2 The F-NiCoS-OH composite significantly increases the specific surface area, thereby exposing more active sites and improving electrolyte contact. Although the specific surface area of ​​F-NiCoS-OH decreases to 263.5 m², the overall surface area remains relatively stable. 2 / g, but its mesopore area is as high as 242.9m². 2 / g, which is beneficial to the improvement of supercapacitor performance. Meanwhile, the mesoporous area ratio of F-NiCoS-OH reaches 92.2%, far higher than that of F-NiCoS (45.3%), indicating a significant increase in the active surface accessible to the electrolyte, which is extremely beneficial for improving specific capacitance. Furthermore, F-NiCoS-OH has the smallest average pore size, only 9.2 nm, about half that of F-NiCoS, highlighting the ability of alkali treatment to finely control the pore structure. The significant reduction in average pore size can accelerate the ion diffusion rate, thereby significantly optimizing rate performance. At the same time, a reasonable mesoporous area and pore size can significantly shorten the ion diffusion path and alleviate structural collapse caused by volume expansion / contraction during cycling, thus affecting power density and cycling performance. To investigate the surface charge characteristics of F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH, Zeta potential tests were conducted to verify their charge states. Figure 15 As shown, the Zeta potentials of F-NiS, F-CoS, and F-NiCoS are -1.09 mV, -4.25 mV, and -1.12 mV, respectively, all exhibiting negative charge and falling far short of the ±30 mV stability threshold, indicating poor dispersibility in solution and a tendency for particle agglomeration. The Zeta potential of F-NiCoS falls between that of F-NiS and F-CoS, possibly due to the interaction of the nickel-cobalt composite structure. In contrast, the Zeta potential of F-NiCoS-OH is 0.06 mV, significantly different from the other three materials, indicating that the nickel-cobalt composite and hydroxylation treatment altered the surface chemical environment. F-NiCoS-OH has a near-zero surface charge and minimal electrostatic repulsion between particles, making it more prone to aggregation during dispersion. This may be attributed to the OH groups introduced by the alkali treatment. - The complexity of the mesoporous structure leads to the neutralization or redistribution of surface charges, significantly compressing the thickness of the electrical bilayer. However, moderately reducing the surface negative charge may facilitate the adsorption and diffusion of electrolyte ions within the electrode, thereby enhancing interfacial reaction kinetics.

[0072] The chemical states of the surface elements in four samples—F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH—were characterized using X-ray photoelectron spectroscopy (XPS). Figure 2 As shown in (b), the XPS full spectrum confirmed the presence of Ni, Co, S, Fe, C, N, and O elements in the sample. Fe, C, and N undoubtedly originate from the PBA framework (see Table 2 below). Due to their low concentrations, F and Na signals were not easily detected. A K2p peak was detected at 295 eV in the F-NiCoS-OH sample, but not in the other three samples, indicating that the K element originated from the alkali treatment process. Figure 2 As shown in (c), in the Ni 2p region, the XPS spectrum is deconvolved into Ni 2+ Ni 3+ And its satellite peaks. The peaks at 856.3 eV and 873.9 eV are attributed to Ni. 2+ 2p 3 / 2 and Ni 2+ 2p 1 / 2 The peaks at 857.7 eV and 875.7 eV correspond to Ni. 3+ 2p 3 / 2 and Ni 3+ 2p 1 / 2 The peaks near 862.3 eV and 880.4 eV are satellite peaks. For high-resolution XPS of Co 2p, such as... Figure 2 As shown in (d), the spectrum was deconvolved into two sets of main peaks. The peaks at 781.9 eV and 796.9 eV are assigned to Co. 3+ 2p 3 / 2 and Co 3+ 2p 1 / 2 The peaks at 784.2 eV and 799.2 eV correspond to Co. 2+ 2p 3 / 2 and Co 2+ 2p 1 / 2 The peaks near 788.2 eV and 803.2 eV are satellite peaks. In the S2p spectrum, as shown... Figure 2 As shown in (ef), the XPS peaks are attributed to SO and MS bonds. The peaks at 168.9 eV and 170.1 eV correspond to SO 2p bonds, respectively. 3 / 2 and SO 2pp 1 / 2 The peaks at 162.5 eV and 163.7 eV correspond to M-S2p. 3 / 2 and M-S2p 1 / 2 .like Figure 2 As shown in (g), the XPS peak positions of the four samples are displayed. Compared with single metal sulfides, Ni in F-NiCoS 2+ 2p 3 / 2 Co 3+ 2p3 / 2 and M-S2p 3 / 2 The peak positions shift towards higher binding energies, indicating successful construction of the heterostructure. After alkali treatment, the peak positions shifted overall towards lower binding energies, suggesting that OH... - The surface electronic structure of F-NiCoS-OH was modulated. For example... Figure 2 As shown in (h), compared to single metal sulfides, Ni in the F-NiCoS heterostructure... 2+ and Co 2+ The proportion of MS / SO increases. In F-NiCoS-OH, this proportion continues to increase, which is beneficial for electrochemical energy storage. The MS / SO ratio of the F-NiCoS heterostructure is lower than that of F-NiS and F-CoS. After alkali treatment, this ratio decreases further, indicating a decrease in MS content or an increase in SO content. Figure 2 As shown in (i), F-NiCoS-OH exhibits the lowest S / (Ni+Co) ratio, confirming that alkali treatment significantly reduces sulfur content. Referring to Table 3 below, compared to the other three samples, F-NiCoS-OH has the lowest sulfur content and the highest oxygen content. Figure 16 As shown in (a) of the spectrum, in the O1s spectrum, the peaks at 531.6 eV and 532.3 eV are assigned to M-OH and C=O bonds (denoted as O1 and O2), respectively, while the peak at 533.2 eV corresponds to the CO bond (O3). Figure 16 As shown in (b), the ratio of O1 to O2 increases after alkali treatment, indicating that more oxygen enters the crystal lattice and forms chemical bonds with the metal.

[0073] Table 2. Na and F atom content in each sample

[0074]

[0075] Table 3. S and O atom content in each sample

[0076]

[0077] In summary, the attenuation of the PBA diffraction peak in XRD and the decrease in sulfur content in XPS indicate that alkali treatment successfully introduced oxygen into the structure of the F-NiCoS-OH sample. This process may involve trace amounts of [Fe(CN)3]. 3- Ions are OH -The oxygen atoms replace sulfur atoms in the metal sulfide lattice, thus forming metal hydroxides. Since no clear hydroxide diffraction peaks were observed in the XRD pattern and no MO bonds were detected in the XPS spectrum, this introduction pathway is not the mainstream mechanism for oxygen introduction. More likely, oxygen atoms replace some sulfur atoms in the metal sulfide lattice, thereby achieving oxygen doping. The introduction of oxygen atoms can improve the wettability of the electrode surface, promote redox potential and reaction kinetics, and thus enhance the overall energy storage performance. Therefore, the F-NiCoS-OH composite material integrates dual-ion doping and a complex heterostructure, and can improve conductivity and increase electrochemical active sites through surface atomic reconstruction and charge diffusion optimization, thereby improving the electrochemical performance of supercapacitors.

[0078] In addition, regarding electrochemical performance, see [reference needed]. Figure 3 , Figure 3 Electrochemical characterization results of NiCoS and F-NiCoS are presented. The test system was a 1M KOH electrolyte, and the methods included cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Figure 3 As shown in (a) of the figure, the area enclosed by the CV curve of F-NiCoS is significantly larger than that of NiCoS, indicating that it has higher capacitance behavior. Figure 3 As shown in (b) of the figure, the GCD curves reveal a longer discharge time for F-NiCoS, further confirming its superior performance; the more symmetrical charge-discharge curves indicate that F doping improves coulombic efficiency and optimizes conductivity. Figure 17 As shown, CV curves for 1-5 mV / s and GCD curves for 1-10 A / g are provided. Figure 3 As shown in (c), at 1 A / g, the specific capacitance of F-NiCoS is 457.8 F / g, while that of NiCoS is 373.3 F / g; when the current density is increased to 10 A / g, F-NiCoS still maintains 288.9 F / g, and NiCoS maintains 244.4 F / g, with capacity retention rates of 63.1% and 65.5%, respectively. The capacity improvement is attributed to optimized conductivity and enhanced electrochemical activity. Figure 3 As shown in (d), conductivity can be evaluated by EIS (the inset shows the fitted equivalent circuit), and the ohmic resistance (Rs), charge transfer resistance (Rct), and diffusion resistance (Rw) are obtained by fitting.

[0079] Table 4 Comparison of electrical conductivity between NiCoS and F-NiCoS

[0080] Rs(Ω) Rct(Ω) W(Ω) NiCoS 1.44 0.63 0.68 F-NiCoS 1.58 0.52 0.64

[0081] Referring to Table 4 above, the results show that the Rct (0.52Ω) and Rw (0.64Ω) of F-NiCoS are both lower than those of NiCoS, indicating that its electron and ion transport dynamics are faster. Figure 18In the Bode phase diagram shown, the relaxation time constant τ0 of NiCoS is approximately 3.55 s, while that of F-NiCoS is only 2.29 s, indicating that F doping significantly accelerates the charge response. Figure 19 As shown, electrochemical activity was evaluated using the electrochemically active surface area (ECSA), derived from the CV curve of the non-Faradaic region, where the current originates solely from the electric double layer. Figure 3 As shown in (e), the double-layer capacitance Cdl of F-NiCoS is 0.44 mF / cm, which is higher than that of NiCoS (0.37 mF / cm), indicating that F doping activates more active sites. According to Equations 1-4 below, the reaction kinetics utilize i = av b Analyzing the equation log(i) = blog(v) + log(a), b = 0.5 indicates diffusion control, and b = 1.0 indicates adsorption control. As shown in Figure (f), the b values ​​for the oxidation and reduction peaks of NiCoS are 0.72 and 0.71, respectively, while those for F-NiCoS are both 0.70, indicating that both are controlled by adsorption and diffusion. The slightly lower b value of F-NiCoS suggests that F, as a heteroatom, regulates the electronic structure and contributes additional electrochemical capacity.

[0082] i = av b (Formula 1); log(i) = b log(+log(a) (Formula 2);

[0083] i = k1v + k2v 1 / 2 (Formula 3); i / v 1 / 2 =k1v 1 / 2 +k2 (Formula 4).

[0084] In summary, the performance improvement of F-NiCoS can be attributed to the high electronegativity of F attracting Ni / Co electrons, causing partial oxidation of metal ions and generating more high-valence redox centers. These centers can participate in multi-electron transfer reactions, increasing the contribution of pseudocapacitance. At the same time, the introduction of F leads to lattice distortion and local electronic polarization, forming electron transport channels, improving intrinsic conductivity and promoting rapid charge transfer.

[0085] Also, see Figure 4 To systematically explore the impact of multidimensional structural regulation on energy storage performance, a series of electrochemical tests were conducted on F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH. Figure 4The CV curve in (a) shows that the integral area of ​​F-NiCoS-OH is significantly larger than that of F-NiS, F-CoS, and F-NiCoS, indicating that it has the highest specific capacitance. Compared with F-NiS, the redox peak potentials of F-NiCoS and F-NiCoS-OH are closer, indicating that the two metal sulfides have formed a composite structure. The CV curve of F-NiS shows obvious redox peaks, reflecting battery-like energy storage characteristics; Figure 20 As shown, the F-CoS curve is nearly rectangular, indicating pseudocapacitive energy storage characteristics. Given the different energy storage mechanisms of the two, constructing heterojunctions can synergistically improve energy storage performance. Figure 4 In the GCD curves of (b) above, F-CoS exhibits a symmetrical triangle shape, consistent with pseudocapacitive behavior; F-NiS shows a plateau, corresponding to Faraday storage characteristics; F-NiCoS and F-NiCoS-OH combine characteristics of both. Benefiting from its complex structure, F-NiCoS-OH exhibits the longest discharge time, indicating its optimal specific capacity. Furthermore, to prevent structural collapse, the operating voltage window of F-NiS is limited to 0-0.4V; while the Co-containing sample extends this window to 0-0.45V, which is beneficial for improving energy density.

[0086] Table 5 Comparison of electrical conductivity of each sample

[0087] Rs(Ω) Rct(Ω) W(Ω) F-NiS 1.73 0.64 1.06 F-CoS 1.52 0.30 0.76 F-NiCoS 1.58 0.52 0.64 F-NiCoS-OH 1.23 0.81 0.57

[0088] Table 5 and Figure 4 The Nyquist plot in (c) shows that the impedance parameters of F-NiCoS (Rs = 1.58 Ω, Rct = 0.52 Ω, Rw = 0.64 Ω) are between those of F-CoS and F-NiS, highlighting the regulatory role of the heterostructure. F-NiCoS-OH has the lowest Rs (1.23 Ω) and Rw (0.57 Ω), indicating that alkaline treatment improves electrode-electrolyte contact and accelerates mass transfer; however, its Rct (0.81 Ω) is the highest, which may be attributed to the slow introduction of oxygen leading to a decrease in crystallinity and an increase in interparticle impedance, thereby hindering charge transfer. Figure 21 The Bode phase diagram shows that the relaxation time constants τ0 of F-NiS, F-CoS, F-NiCoS and F-NiCoS-OH are 10.41s, 0.70s, 2.29s and 2.64s, respectively, indicating that the heterojunction significantly accelerates charge storage and improves rate performance; however, after alkali treatment, the pseudocapacitance caused by the introduction of oxygen increases, and τ0 increases slightly.

[0089] Figure 4 Figure (d) shows the GCD curves of F-NiCoS-OH at different current densities. The highly symmetrical curves indicate the excellent reversibility of the redox reaction. To further elucidate the advantages brought by the heterostructure and oxygen doping, Figure 4(e) shows a comparison of the specific capacitance of F-NiS, F-CoS, F-NiCoS, and F-NiCoS-OH at various current densities. At 1 A / g, the specific capacitance of F-NiCoS-OH is as high as 680 F / g, which is much higher than that of F-NiCoS (458 F / g), F-NiS (493 F / g), and F-CoS (133 F / g). When the current density increases to 10 A / g, F-NiCoS-OH still retains 58.8% of its initial capacitance, showing good rate performance, while the capacitance retention rates of F-NiS, F-CoS, and F-NiCoS are 3.1%, 58.4%, and 63.1%, respectively. Overall, F-NiS has high specific capacitance but limited rate performance, while F-CoS is the opposite, with lower capacitance but excellent rate performance. By utilizing the complementary properties of the two metal sulfides, F-NiCoS achieves a balance between high capacitance and excellent rate performance, verifying the effectiveness of the heterostructure construction. Furthermore, thanks to the synergistic effect of heteroatoms, heterostructures, and porous structures in charge transport, F-NiCoS-OH achieved the highest specific capacitance.

[0090] Table 6. TMS-based electrode materials

[0091]

[0092]

[0093] Referring to Table 6 above, which summarizes TMS-based electrode materials, it can be seen that the supercapacitor performance of F-NiCoS-OH is at a comparable level. Through... Figure 22 and Figure 19 (b) in the paper evaluated the ECSA of four samples, such as Figure 4 As shown in (f), its double-layer capacitance Cdl is as follows: F-NiCoS-OH 0.65mF cm -1 F-NiCoS 0.44mF cm -1 F-NiS 0.40mF cm -1 F-CoS9.59mF cm -1 Among them, F-CoS has an order-of-magnitude advantage due to its stronger pseudocapacitive properties, providing a larger electrochemically active surface. However, among the other three samples, F-NiCoS-OH has the largest Cdl, indicating that alkaline treatment effectively activates more energy storage sites.

[0094] To further explore the kinetic basis for the performance improvement of the F-NiCoS-OH electrode, kinetic analysis was performed on four samples. For example... Figure 4As shown in (g), the CV curve shape of F-NiCoS-OH remained highly consistent with increasing scan rate, indicating its excellent redox reversibility; however, the polarization effect caused a slight peak shift. To avoid the significant impact of polarization on the kinetic test, the scan rate was limited to 1-5 mV s. -1 .like Figure 4 As shown in (h), the b-values ​​of F-NiCoS-OH, F-NiCoS, F-NiS, and F-CoS are 0.65, 0.70, 0.52, and 0.96, respectively. The b-value of F-NiS is close to 0.5, and the b-value of F-CoS is close to 1, indicating that diffusion and adsorption control are dominant, consistent with CV morphology analysis. The b-values ​​of F-NiCoS-OH and F-NiCoS are between 0.5 and 1.0, indicating that adsorption and diffusion processes synergistically contribute to the total capacity. The smaller b-value of F-NiCoS-OH suggests that oxygen modification enhances diffusion control, which is beneficial for capacity improvement. Figure 4 As shown in (i), the capacitance contribution of F-NiCoS-OH at different scan rates was compared, 5 mV s -1 The adsorption control contribution reached 72.3%, and the adsorption contribution further increased with increasing scan rate while the diffusion contribution weakened, which is attributed to the restricted intercalation of lattice ions.

[0095] In summary, the enhanced performance of the F-NiCoS-OH supercapacitor stems from the complementary effects of doping and the heterojunction, as well as the defect-interface synergistic enhancement mechanism. First, heteroatom doping optimizes the electronic structure, while the heterojunction enhances charge separation and transport efficiency through an endogenous electric field. Together, they construct a multidimensional conductive network, exposing active sites and accelerating reaction kinetics. Second, the interaction between the lattice mismatch at the heterojunction interface and the defects introduced by doping forms high-density charge transfer channels and reaction sites, significantly improving rate performance. Furthermore, the synergistic effect of F and O further optimizes active sites and electron conduction, accelerating electrochemical reaction kinetics. The highly electronegative F stabilizes the electronic structures of Ni and Co, optimizing the performance of OH. - The adsorption energy promotes efficient energy storage reactions, while O-induced surface hydroxyl groups provide additional reaction sites, increasing the active centers for Faraday reactions; therefore, dual-ion doping optimizes the interface structure, eliminates electrostatic barriers, and promotes OH- adsorption. - The transfer of oxygen increases capacity; at the same time, the chemical inertness of F inhibits the dissolution of metal sites, and the introduction of O improves the structural stability in the alkaline electrolyte. This synergistic effect was verified in subsequent cycle stability tests.

[0096] See Figure 5 The electrochemical stability of F-NiCoS-OH was tested, and its morphology, crystal structure, elemental valence states, and electronic structure were systematically characterized after 10,000 cycles. Figure 5As shown in (a), F-NiCoS-OH retains 95% of its initial capacitance after 10,000 cycles, with a coulombic efficiency consistently close to 100%, demonstrating excellent cycle stability and a highly reversible charge-discharge process. This superior cycle stability can be attributed to the structural stability provided by the mesoporous structure during long-term redox processes, while the heterostructure combines the structural advantages of nickel and cobalt complexes, reducing capacity loss during cycling. Figure 5 (b) compares the Nyquist plots of F-NiCoS-OH before and after cycling (see Table 7 below). After cycling, Rs (1.26Ω) and Rct (0.87Ω) remain almost unchanged, while Rw (0.45Ω) decreases significantly, indicating enhanced ion diffusion kinetics, which may be related to the structural reconstruction of the electrode material. After 10,000 cycles, F-NiCoS-OH still maintains its nanoparticle morphology, such as... Figure 5 As shown in (c), no obvious nanosheet structure was observed. XRD analysis showed that the PBA structure was further weakened, as... Figure 5 As shown in (d), no obvious metal sulfide diffraction peaks were detected. The diffraction signals were attributed to Ni(OH)₂ (JCPDS#73-1520) and CoOOH (JCPDS#26-0480), accompanied by sharp diffraction peaks of the Ti current collector (JCPDS#44-1294). Figure 5 As shown in (e), the Fe, C, and N signals originate from PBA, while the F signal is affected by the binder used in electrode fabrication; the S signal is still detectable, but its content has decreased to 3.75%, only 48% of the level before cycling. The satellite peak intensity in the Ni 2p high-resolution XPS spectrum has significantly increased, indicating changes in the spin state and coordination environment of Ni. Figure 5 Ni in (f) 2+ Concentration increased; Figure 5 Co in (g) 3+ The peak intensity is significantly enhanced. The S2p high-resolution spectrum mainly shows SO bonds. Figure 5 There are almost no MS peaks in (h) of Ni. 2+ / Ni 3+ and Co 2+ / Co 3+ The peak area ratios were 2.59 and 0.53, respectively, compared to 1.77 and 1.22 before the cycle. Figure 5 (i) in the text indicates that Ni 2+ With Co 3+ Increased content; the MS / SO ratio approaching zero confirms significant loss of metal sulfides. Meanwhile, as... Figure 23As shown, no MO bonds were detected in the O 1s high-resolution spectrum. Overall, after electrochemical testing in alkaline medium, F-NiCoS-OH transformed from a metal sulfide into a metal hydroxide and hydroxy oxide dominated by Ni(OH)2 and CoOOH.

[0097] Table 7 Comparison of conductivity properties of F-NiCoS-OH before and after cycling test

[0098] Rs(Ω) Rct(Ω) W(Ω) Before the test 1.23 0.81 0.57 After testing 1.26 0.87 0.45

[0099] See Figure 6 To evaluate its practical application potential, a system was assembled using F-NiCoS-OH as the positive electrode, CNTs as the negative electrode, and 1M KOH as the electrolyte. Figure 6 The asymmetric supercapacitor F-NiCoS-OH / / CNTASC shown in (a) is described below. The polarity matching and capacitance calculation methods are shown in Formulas 5-8.

[0100]

[0101] See Figure 24 The CNT electrode exhibits typical electric double-layer capacitance (EDLC) characteristics within the -1V to 0V window. By integrating EDLC with Faraday capacitance behavior, the device extends its operating voltage window to 1.45V. Figure 6 (b) gives 100mV s -1 The CV curves for different voltage windows show that as the window size increases, the CV area expands synchronously, reaching its maximum capacity at 1.45V without significant polarization, confirming 1.45V as the optimal operating range. Within a fixed 1.45V window, the CV remains rectangular even at high scan rates. Figure 6 (c) indicates excellent rate performance. Figure 6 The GCD curve in (d) is nearly symmetrical, reflecting high coulombic efficiency and excellent reversibility. Figure 6 The device in (e) has a specific capacitance of 75.9 F / g at 1 A / g and retains 80% (60.3 F / g) at 7 A / g; Figure 6 (f) shows its energy density at 725 W / kg. -1 At power, it is 22.2Wh / kg. -1 5075W kg -1 At power, it is 17.6Wh / kg. -1 Its performance is comparable to that of the TMS-based ASCII devices listed in Table 8 below.

[0102] Table 8 Electrochemical performance of TMS-based ASCII devices

[0103]

[0104] Table 9. Conductivity of F-NiCoS-OH / / CNT before and after cycling tests

[0105] Rs(Ω) Rct(Ω) W(Ω) Before the test 2.00 1.13 1.66 After testing 2.03 0.92 1.04

[0106] Long-term cyclic experiments show that Figure 6 As shown in (g), after 10,000 cycles, the device retains 88% of its capacity and achieves 100% coulombic efficiency, demonstrating excellent stability and reversibility. Figure 6 As shown in (h) and Table 9 above, Rs (2.03Ω) remained almost unchanged after cycling, while Rct (0.92Ω) and Rw (1.04Ω) further decreased, indicating enhanced ion and electron transport kinetics, further demonstrating the excellent cycling stability of F-NiCoS-OH / / CNT. Figure 25 As shown, the τ0 values ​​before and after the device cycling are 1.34 s and 1.04 s, respectively. The decrease in τ0 indicates that the charge response is faster after cycling, and the charge transfer in the conductive network is improved, which is consistent with the EIS results.

[0107] In summary, the synthesized F-NiCoS-OH material exhibits excellent electrochemical performance through the synergistic regulation of heteroatoms, heterostructure, and mesoporous structure across multiple dimensions.

[0108] (1) F and O co-doping effectively modulates the electronic structure of F-NiCoS-OH, thereby enhancing the reactivity and accelerating charge and ion transport kinetics;

[0109] (2) The heterostructure integrates the energy storage properties of nickel and cobalt sulfides, promotes mass and charge transfer, optimizes reaction kinetics and enhances electrochemical stability;

[0110] (3) The plate-like and mesoporous structures induce lattice distortion, generate defect states, and jointly expose active sites, thereby improving conductivity and extending cycle life.

[0111] In summary, this invention successfully fabricated a Ni-Co-S mesoporous heterostructure electrode (F-NiCoS-OH) with F and O co-controlled structure through a meticulously designed three-step method combining heteroatom doping and heterostructure engineering. This unique structure optimizes the interface configuration, enables unimpeded electron transport, and significantly improves electrochemical performance. Specifically, F-NiCoS-OH exhibits a high specific capacitance of 680 F / g at 1 A / g, a capacity retention of 58.8% at 10 A / g, and retains 95% of its initial capacity after 10,000 cycles at 10 A / g. The asymmetric supercapacitor F-NiCoS-OH / / CNT assembled with carbon nanotubes (CNTs) achieves a power density of 725 W / kg. -1 Achieved 22.2Wh kg -1It has high energy density and exhibits excellent cycle stability.

[0112] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing F-NiCoS-OH composite material, characterized in that: The method comprises the following steps: S1: dissolving a nickel salt, a cobalt salt and a fluorine source in water to obtain solution A, dissolving potassium ferricyanide in water to obtain solution B, mixing solution A and solution B to perform a co-precipitation reaction to obtain a F-NiCo-PBA precursor; S2: dissolving the F-NiCo-PBA precursor obtained in S1 in anhydrous ethanol to obtain solution C, dissolving a sulfur source in water to obtain solution D, mixing solution C and solution D to perform a hydrothermal sulfuration reaction to obtain F-NiCoS; S3: mixing the F-NiCoS obtained in S2 with an alkali solution to perform an alkali treatment to obtain F-NiCoS-OH.

2. The preparation method of the F-NiCoS-OH composite material according to claim 1, characterized in that: The molar ratio of the nickel salt, the cobalt salt and the fluorine source in solution A in S1 is 1:0.8-1.2:2.5-30.

3. The preparation method of the F-NiCoS-OH composite material according to claim 2, characterized in that: The nickel salt is NiCl2·6H2O, the cobalt salt is CoCl2·6H2O, and the fluorine source is NaF.

4. The preparation method of the F-NiCoS-OH composite material according to claim 1, characterized in that: The mass ratio of the F-NiCo-PBA precursor to the sulfur source in S2 is 1:1.8-2.2, and the sulfur source is thiourea.

5. The preparation method of the F-NiCoS-OH composite material according to claim 1, characterized in that: The reaction temperature of the hydrothermal sulfuration reaction in S2 is 150-180 DEG C, and the time is 2-4 h.

6. The preparation method of the F-NiCoS-OH composite material according to claim 1, characterized in that: The alkali solution in S3 is a KOH solution.

7. The F-NiCoS-OH composite material prepared by the method for preparing the F-NiCoS-OH composite material according to any one of claims 1-6.

8. Application of the F-NiCoS-OH composite material according to claim 7 to electrode materials, supercapacitors, portable electronic devices and electric vehicles.

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