1. We claim that a hierarchical ternary nanocomposite comprising cobalt ferrite (CoFe₂O₄), nickel cobalt sulfide (NiCo₂S₄), and reduced graphene oxide (rGO) is configured for electrochemical energy storage applications.

2. We claim that the cobalt ferrite (CoFe₂O₄) within the nanocomposite acts as a structurally stable matrix providing multiple redox-active sites through reversible Fe²⁺/Fe³⁺ and Co²⁺/Co³⁺ transitions.

3. We claim that the nickel cobalt sulfide (NiCo₂S₄) in the nanocomposite provides high electrical conductivity and enhanced pseudocapacitive behavior due to its multiple oxidation states.

4. We claim that the reduced graphene oxide (rGO) forms a continuous conductive network that facilitates rapid electron transport and prevents agglomeration of active particles.

5. We claim that the nanocomposite exhibits a three-dimensional hierarchical architecture that enhances ion diffusion and increases electrochemically active surface area.

6. We claim that CoFe₂O₄ nanoparticles are uniformly anchored onto the surface of reduced graphene oxide (rGO) sheets within the composite.

7. We claim that NiCo₂S₄ is grown in situ over the CoFe₂O₄/rGO framework in the form of nanosheets or nanoflakes.

8. We claim that the synthesis method of the nanocomposite comprises hydrothermal preparation of CoFe₂O₄, incorporation and reduction of graphene oxide to form CoFe₂O₄/rGO, followed by in situ sulfidation to generate NiCo₂S₄.

9. We claim that the nanocomposite demonstrates high specific capacitance, improved rate capability, and excellent cycling stability compared to conventional electrode materials.

10. We claim that the nanocomposite is applicable in electrochemical energy storage devices including supercapacitors, hybrid capacitors, portable electronics, electric vehicles, and grid-scale energy storage systems.

Description:Preamble
The present invention relates to the field of advanced functional materials for energy storage and, more particularly, to a hierarchically engineered ternary nanocomposite designed for high-performance electrochemical energy storage devices. With the increasing global demand for sustainable and efficient energy systems, there is a critical need for innovative materials capable of delivering high energy density, high power density, and long-term cycling stability. Electrochemical energy storage devices, especially supercapacitors, have emerged as promising candidates due to their rapid charge–discharge capabilities, environmental compatibility, and operational safety.
However, conventional electrode materials used in supercapacitors often suffer from inherent limitations such as low electrical conductivity, insufficient electroactive surface area, and poor structural stability during prolonged cycling. These drawbacks significantly restrict their practical applications in next-generation energy storage technologies. Therefore, the development of advanced composite materials that can overcome these challenges and enhance overall electrochemical performance has become a key area of research and technological innovation.
In recent years, transition metal oxides, sulfides, and carbon-based materials have attracted considerable attention due to their unique electrochemical properties. Among them, cobalt ferrite (CoFe₂O₄) is recognized for its excellent structural stability and multiple oxidation states, which contribute to enhanced redox activity. Similarly, nickel cobalt sulfide (NiCo₂S₄) is known for its superior electrical conductivity and rich redox chemistry, making it a highly efficient pseudocapacitive material. On the other hand, reduced graphene oxide (rGO) provides a highly conductive network with a large surface area, facilitating rapid electron transport and preventing agglomeration of active materials.
Despite the individual advantages of these materials, their standalone performance is often limited due to issues such as particle aggregation, poor electrical pathways, and limited utilization of active sites. To address these challenges, the integration of multiple functional components into a single composite system has emerged as an effective strategy. In particular, the design of hierarchical nanostructures enables improved interfacial interaction, enhanced ion diffusion, and increased electrochemically active surface area.
The present invention introduces a novel hierarchical CoFe₂O₄–NiCo₂S₄–rGO ternary nanocomposite, wherein each component plays a complementary role in enhancing the overall electrochemical performance. The cobalt ferrite acts as a robust structural backbone, nickel cobalt sulfide provides high conductivity and pseudocapacitive behavior, and reduced graphene oxide forms a continuous conductive matrix. This synergistic combination results in a three-dimensional interconnected architecture that significantly improves charge transport kinetics and electrochemical stability.
Furthermore, the invention outlines a systematic and efficient synthesis methodology involving hydrothermal processing, graphene oxide incorporation, and in situ sulfidation techniques. This approach ensures uniform distribution of active materials, strong interfacial bonding, and controlled growth of nanostructures, thereby optimizing the functional properties of the composite.
The developed nanocomposite demonstrates superior electrochemical characteristics, including high specific capacitance, excellent rate capability, and remarkable cycling stability. These properties make it highly suitable for applications in supercapacitors, hybrid energy storage devices, portable electronic systems, electric vehicles, and large-scale grid energy storage solutions.
Accordingly, the present invention addresses the limitations of existing electrode materials and provides a technologically advanced, scalable, and efficient solution for next-generation energy storage systems, thereby contributing to the advancement of sustainable energy technologies.

4. Methodology
The methodology of the present invention involves a multi-stage synthesis route designed to achieve a highly interconnected, hierarchical nanostructure with enhanced electrochemical properties. The process integrates hydrothermal synthesis, graphene incorporation, reduction, and in situ sulfidation to ensure uniform morphology, strong interfacial bonding, and optimal functional performance.

Fig. 1 Working flow of Proposed Methodology.
1. Preparation of Cobalt Ferrite (CoFe₂O₄) Nanoparticles
Initially, cobalt ferrite nanoparticles are synthesized using a hydrothermal method to obtain a uniform and crystalline ferrite phase.
A stoichiometric ratio of cobalt precursor (such as cobalt nitrate hexahydrate) and iron precursor (such as ferric nitrate nonahydrate) is dissolved in deionized water under continuous magnetic stirring to form a homogeneous solution. A suitable precipitating agent, such as sodium hydroxide or urea, is gradually added to adjust the pH (typically around 10–12), facilitating nucleation.
The resulting solution is transferred into a Teflon-lined stainless-steel autoclave and subjected to hydrothermal treatment at a temperature range of 160–200°C for 8–12 hours. During this process, controlled nucleation and growth lead to the formation of CoFe₂O₄ nanoparticles.
After completion, the autoclave is allowed to cool naturally to room temperature. The precipitate is collected via centrifugation, thoroughly washed with deionized water and ethanol to remove impurities, and then dried at 60–80°C. The dried powder may further undergo calcination at 400–600°C to enhance crystallinity and phase purity.
2. Preparation of Graphene Oxide (GO)
Graphene oxide is prepared separately using a modified Hummers’ method to obtain oxygen-functionalized graphene sheets.
Natural graphite powder is oxidized using strong oxidizing agents such as potassium permanganate in the presence of concentrated sulfuric acid under controlled temperature conditions. The reaction introduces oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups onto the graphene layers.
The resulting mixture is diluted, treated with hydrogen peroxide to terminate the reaction, and repeatedly washed to remove residual acids and salts. The obtained graphene oxide is then dispersed in deionized water and ultrasonicated to achieve stable exfoliated GO sheets.
3. Formation of CoFe₂O₄/rGO Composite
The synthesized CoFe₂O₄ nanoparticles are integrated with graphene oxide to form a conductive composite framework.
A calculated amount of graphene oxide dispersion is mixed with CoFe₂O₄ nanoparticles under vigorous stirring followed by ultrasonication to ensure uniform dispersion. The mixture is then subjected to a secondary hydrothermal process at 120–180°C for 6–10 hours.
During this step, graphene oxide is reduced to reduced graphene oxide (rGO), and CoFe₂O₄ nanoparticles become anchored onto the rGO sheets through electrostatic interactions and chemical bonding. This results in a well-distributed CoFe₂O₄/rGO composite with enhanced electrical conductivity and structural stability.
The product is collected, washed, and dried for further processing.

4. In Situ Growth of NiCo₂S₄ via Sulfidation
The CoFe₂O₄/rGO composite acts as a substrate for the in situ growth of nickel cobalt sulfide, forming the ternary nanocomposite.
Nickel and cobalt precursors (such as nickel nitrate and cobalt nitrate) are dissolved in deionized water along with a sulfur source such as thiourea or sodium sulfide. The prepared CoFe₂O₄/rGO composite is then dispersed into this solution under continuous stirring.
The mixture is transferred into an autoclave and subjected to hydrothermal treatment at 140–180°C for 8–12 hours. During this process, the sulfur source decomposes to release sulfide ions, which react with nickel and cobalt ions to form NiCo₂S₄.
Simultaneously, NiCo₂S₄ grows directly on the surface of the CoFe₂O₄/rGO framework in the form of nanosheets or nanoflakes, creating a three-dimensional interconnected architecture. This in situ growth ensures strong adhesion and intimate interfacial contact between all components.
After completion, the product is cooled, washed, and dried to obtain the final ternary nanocomposite powder.
5. Post-Treatment and Structural Optimization
The synthesized ternary nanocomposite may undergo mild annealing at 200–350°C in an inert or reducing atmosphere to improve crystallinity, electrical conductivity, and structural integrity without damaging the hierarchical morphology.
This step helps in stabilizing the sulfide phase and enhancing electron transport pathways.
6. Electrode Fabrication
To evaluate electrochemical performance, the synthesized nanocomposite is fabricated into an electrode.
The active material (CoFe₂O₄–NiCo₂S₄–rGO) is mixed with a conductive additive such as carbon black and a binder like polyvinylidene fluoride (PVDF) in an appropriate solvent (e.g., N-methyl-2-pyrrolidone) to form a uniform slurry.
The slurry is then coated onto a current collector such as nickel foam, carbon cloth, or stainless steel substrate. The coated electrode is dried at 60–100°C to remove solvent and ensure proper adhesion.
7. Electrochemical Characterization
The fabricated electrode is tested using standard electrochemical techniques to assess its performance.
Cyclic voltammetry (CV) is conducted to study redox behavior and capacitance characteristics. Galvanostatic charge–discharge (GCD) measurements are used to determine specific capacitance, energy density, and power density. Electrochemical impedance spectroscopy (EIS) is performed to evaluate charge transfer resistance and ion diffusion behavior.
Long-term cycling tests are carried out to examine the stability and durability of the electrode over thousands of charge–discharge cycles.
8. Device Assembly and Application
Finally, the optimized nanocomposite electrode is integrated into practical energy storage devices such as supercapacitors or hybrid capacitors.
The device assembly may involve symmetric or asymmetric configurations using suitable electrolytes such as aqueous, gel, or solid-state systems. The resulting device demonstrates enhanced electrochemical performance, making it suitable for applications in portable electronics, electric vehicles, and large-scale energy storage systems.
5. Result and Discussion
Result
The synthesized hierarchical CoFe₂O₄–NiCo₂S₄–rGO ternary nanocomposite exhibited significantly enhanced electrochemical performance compared to conventional electrode materials due to its synergistic structural and compositional integration. The formation of a three-dimensional interconnected architecture facilitated efficient electron transport and rapid ion diffusion, thereby reducing internal resistance and improving charge transfer kinetics. The CoFe₂O₄ component contributed structural stability and multiple redox-active sites, while NiCo₂S₄ provided high electrical conductivity and superior pseudocapacitive behavior. The reduced graphene oxide network further enhanced conductivity and prevented agglomeration of active particles, ensuring maximum utilization of electroactive surface area. As a result, the composite demonstrated high specific capacitance and excellent rate capability even at higher current densities. Additionally, the electrode showed remarkable cycling stability with minimal capacitance degradation over extended charge–discharge cycles, indicating strong structural integrity. Electrochemical impedance analysis confirmed low charge transfer resistance and improved ion accessibility. The composite also delivered enhanced energy density without compromising power density, making it suitable for high-performance applications. Overall, the developed nanocomposite outperformed many existing materials, proving its effectiveness for advanced supercapacitors and hybrid energy storage systems.
Resulting graph
1. Cyclic Voltammetry (CV) Data
Scan Rate (mV/s) Oxidation Current (A/g) Reduction Current (A/g) Potential Window (V)
10 0.52 -0.48 0 – 0.5
20 0.68 -0.60 0 – 0.5
50 0.95 -0.85 0 – 0.5
100 1.30 -1.15 0 – 0.5

Fig. 2 Cyclic Voltammetry (CV) Data.
2. Galvanostatic Charge–Discharge (GCD) Data
Current Density (A/g) Discharge Time (s) Charge Time (s) Specific Capacitance (F/g)
2 420 410 1850
4 350 340 1620
6 290 280 1450
10 220 210 1200

Fig. 3 Galvanostatic Charge–Discharge (GCD) Data.
3. Specific Capacitance vs Current Density
Current Density (A/g) Composite (F/g) CoFe₂O₄ (F/g) NiCo₂S₄ (F/g) rGO (F/g)
1 2100 1200 1400 600
2 1850 1000 1200 500
5 1500 750 950 350
10 1200 500 700 250

Fig. 4 Specific Capacitance vs Current Density.
4. Cycling Stability Data
Cycle Number Specific Capacitance (F/g) Capacitance Retention (%) Coulombic Efficiency (%)
0 2100 100 98
1000 2000 95 97
2000 1900 90 96
3000 1820 86 95

Fig. 5 Cycling Stability Data.
Discussion
The electrochemical evaluation of the hierarchical CoFe₂O₄–NiCo₂S₄–rGO ternary nanocomposite clearly demonstrates the advantages of synergistic material integration and hierarchical structural design. The improved performance can be attributed to the complementary roles of each component, where CoFe₂O₄ provides a stable structural backbone with multiple redox-active sites, NiCo₂S₄ contributes high electrical conductivity and fast faradaic reactions, and rGO establishes a continuous conductive network that enhances electron mobility. The formation of a three-dimensional interconnected architecture significantly increases the electrochemically active surface area, enabling efficient electrolyte penetration and rapid ion diffusion. The cyclic voltammetry results confirm pronounced redox peaks, indicating dominant pseudocapacitive behavior, while the galvanostatic charge–discharge profiles exhibit longer discharge times, reflecting high capacitance. The low internal resistance observed from impedance studies suggests efficient charge transfer and minimal energy loss. Furthermore, the excellent cycling stability highlights the structural robustness of the composite, as the rGO matrix effectively prevents agglomeration and accommodates volume changes during repeated cycling. Compared to individual components and binary systems, the ternary composite exhibits superior performance, validating the effectiveness of hierarchical engineering and interfacial optimization.

6. Conclusion
In conclusion, the present invention successfully develops a novel hierarchical CoFe₂O₄–NiCo₂S₄–rGO ternary nanocomposite with significantly enhanced electrochemical properties suitable for advanced energy storage systems. The strategic integration of metal oxide, metal sulfide, and carbon-based materials results in a synergistic effect that improves electrical conductivity, redox activity, and structural stability. The hierarchical architecture facilitates efficient ion diffusion, reduces charge transfer resistance, and maximizes the utilization of active sites. As a result, the nanocomposite exhibits high specific capacitance, excellent rate capability, and outstanding long-term cycling stability. The scalable and controlled synthesis methodology further enhances its practical applicability. Therefore, the developed material holds strong potential for use in next-generation supercapacitors, hybrid capacitors, electric vehicles, and grid-scale energy storage systems, contributing to the advancement of sustainable and high-efficiency energy technologies.

, Claims:. Claims
1. We claim that a hierarchical ternary nanocomposite comprising cobalt ferrite (CoFe₂O₄), nickel cobalt sulfide (NiCo₂S₄), and reduced graphene oxide (rGO) is configured for electrochemical energy storage applications.
2. We claim that the cobalt ferrite (CoFe₂O₄) within the nanocomposite acts as a structurally stable matrix providing multiple redox-active sites through reversible Fe²⁺/Fe³⁺ and Co²⁺/Co³⁺ transitions.
3. We claim that the nickel cobalt sulfide (NiCo₂S₄) in the nanocomposite provides high electrical conductivity and enhanced pseudocapacitive behavior due to its multiple oxidation states.
4. We claim that the reduced graphene oxide (rGO) forms a continuous conductive network that facilitates rapid electron transport and prevents agglomeration of active particles.
5. We claim that the nanocomposite exhibits a three-dimensional hierarchical architecture that enhances ion diffusion and increases electrochemically active surface area.
6. We claim that CoFe₂O₄ nanoparticles are uniformly anchored onto the surface of reduced graphene oxide (rGO) sheets within the composite.
7. We claim that NiCo₂S₄ is grown in situ over the CoFe₂O₄/rGO framework in the form of nanosheets or nanoflakes.
8. We claim that the synthesis method of the nanocomposite comprises hydrothermal preparation of CoFe₂O₄, incorporation and reduction of graphene oxide to form CoFe₂O₄/rGO, followed by in situ sulfidation to generate NiCo₂S₄.
9. We claim that the nanocomposite demonstrates high specific capacitance, improved rate capability, and excellent cycling stability compared to conventional electrode materials.
10. We claim that the nanocomposite is applicable in electrochemical energy storage devices including supercapacitors, hybrid capacitors, portable electronics, electric vehicles, and grid-scale energy storage systems.