Skip to main content
NCBI home page
RSC Advances logoLink to RSC Advances
. 2026 Oct 7;16(46):60611–60621. doi: 10.1039/d6ra07762e

Vanadium-based metal–organic frameworks as superior electrode materials for high-performance supercapacitors: a comparative study with vanadium sulfides and phosphates

Taimoor Zada a,✉, Usman Habib a, Hafsa Naseer a, Saqib Javed a, Yaseen Muhammad a, Sana Azmat a
PMCID: PMC13643521  PMID: 42846254

Abstract

Recent advancement in electrode materials for achieving high energy density, rapid power supply, and optimal cycling reliability have seen a staggering surge because of significant advancements in energy storage devices. In the modern era, metal–organic frameworks (MOFs) and transition metal sulfides and phosphates have emerged as viable candidates for high-performance electrode materials. Among these, MOFs have gained prominence as electrode materials due to their porous architecture, large surface area, and abundant active sites. Herein, three vanadium-based electrode materials, vanadium–1,2,4,5-benzenetetracarboxylic acid (V–BTCA), vanadium sulfide (VS), and vanadium phosphate (VPO4), were synthesized and comparatively investigated for electrochemical hybrid supercapacitor (HSC) applications. We conducted an in-depth investigation to elucidate the effects of the linker, sulfide, and phosphate on the electrochemical properties of vanadium-based materials. Of the three materials, V–BTCA was identified as the optimum material and coupled with activated carbon (AC) to form an HSC device. The V–BTCA//AC device delivered excellent performance with a specific capacity (Qs) of 730 C g−1 at 0.8 A g−1, an energy density (Ed) of 73.1 Wh kg−1, a power density (Pd) of 6800 W kg−1, and the lowest equivalent series resistance (ESR) value of 0.45 Ω, along with 92.83% stability and a coulombic efficiency of 98.15%. Furthermore, the power law was applied to verify the charge-storage behavior of hybrid devices, with b-values of 0.66–0.71, confirming their hybrid nature. The assembled hybrid device showed strong potential for energy storage applications, highlighting the critical role of electrode compatibility and device-level integration in achieving balanced HSC performance, with V–BTCA//AC exhibiting the most favorable overall performance among the investigated devices.

Three vanadium-based materials with different chemical environments, VBTCA, VS, and VPO4, were explored for hybrid supercapacitor applications. V–BTCA//AC exhibited the most favorable electrochemical performance among the investigated devices.graphic file with name d6ra07762e-ga.webp

1. Introduction

In the modern world, energy crisis is a pivotal problem currently faced by the entire world. Rapid industrialization, the accelerating growth of portable electronic devices and an increasing population require solutions for increased energy demand, as well as an increase in energy storage capacity and the exploration of innovative strategies to meet these demands.1 This work aims to develop sustainable energy storage solutions that support the Sustainable Development Goals (SDGs) and align with global market trends for electrochemical energy systems.2 In the current situation relating to energy storage, lithium-ion batteries (LIBs), sodium-ion batteries (NIBs), and supercapacitors (SCs) are the three energy storage systems that have become highly attractive because of their ability to store a significant amount of energy.3–5 Of these, SCs are particularly suited to many advanced applications because of their very high power density, the ability to charge and discharge rapidly, and longer lifetimes than traditional capacitors and lithium-ion batteries.6 On the negative side, however, SCs have much lower energy density than batteries, and to solve this problem, scientists are developing a new energy storage concept that combines the advantages of batteries and SCs in one device. Most of the scientific literature refers to these types of systems as SCs, batteries or hybrid SCs.7 In this kind of device, a capacitor-type anode acts as the source of high power, maintaining excellent performance under rapid cycling and providing long life cycles.5,8 In contrast, a battery-type cathode provides high specific capacity and energy density.9 On the one hand, carbonaceous materials like activated carbon (AC), graphene, carbon nanotubes, and carbon black are often used as capacitive electrodes.10 On the other hand, metal–organic frameworks (MOFs), phosphides, sulfides, oxides, and other transition-metal compounds have been proposed as battery-grade electrode materials, which are highly suitable for energy-storage devices.11 Among these materials, MOFs have attracted considerable attention for electrochemical energy storage because their high porosity, large surface area, and accessible metal centers can provide abundant sites for electrochemical reactions.12–14 Beyond electrochemical energy storage, MOFs have emerged as multifunctional materials owing to their tunable coordination frameworks, high porosity, adjustable surface chemistry, and ability to incorporate diverse metal centers and organic linkers. These structural characteristics have enabled their utilization in a broad range of applications, including gas adsorption and separation, heterogeneous catalysis, chemical sensing, environmental remediation, drug delivery, and tribological systems. For instance, the integration of MOFs with layered materials such as 1T-MoS2 has demonstrated their potential as functional lubricant additives, where the complementary interfacial properties of the components can improve tribological performance.15 Such multifunctionality demonstrates that MOF properties can be tailored through rational selection of metal nodes, organic linkers, and hybridization strategies for application-specific functions. In electrochemical energy storage, these similar design advantages are particularly attractive because accessible metal centers and porous frameworks can facilitate electrolyte penetration and provide electrochemically active sites. M. S. Khan et al. presented a system composed of MnLiS-MOF/PANI/rGO//AC, which delivered a Qs of 260 C g−1 and Ed 48 Wh kg−1.16 Similarly, G. Wang et al. demonstrated the capacitance and the Ed of PM/CNT/MOF to be 650 F g−1 and 45.93 Wh kg−1, respectively,17 thus confirming the huge potential of MOFs to provide better energy storage systems.18 Transition-metal sulfides are another very important category of electrode materials, as their multiple valence states can easily support faradaic reversible processes. Transition-metal sulfides typically show superior electronic conductivity compared to their corresponding metal oxides and hydroxides.19 This is partly because sulfur has a much lower electronegativity than oxygen. Pandit et al. have developed VS2 films by depositing them as thin layers onto flexible, lightweight stainless-steel supports. After 6000 cycles, the electrode retained about 89% of its initial capacity, and at the same time, it delivered a maximum Pd of 1500 W kg−1, along with an Ed of 25.9 Wh kg−1.20 However, single-metal sulfides may not be sufficient to meet all major requirements on the energy-storage side for practical SC devices, a point which we have ourselves identified at the level of assembled cells. Similarly, transition metal phosphates have been studied extensively owing to their advantageous properties.21 Mirghni et al. prepared a bimetallic phosphate–graphene-foam (nickel–cobalt) material using a hydrothermal technique and found that it had a specific capacity of 86.4 mAh g−1 compared with 64 mAh g−1 for unmodified phosphate. Furthermore, the material delivered an Ed of 34.8 Wh kg−1 and a Pd of 377 W kg−1 at 0.5 A g−1, which demonstrates the suitability of phosphate-based compounds for SCs.22

Despite the growing interest in vanadium-based materials for electrochemical energy storage, systematic comparative investigations of chemically distinct vanadium-based electrodes under identical experimental conditions remain limited. In particular, the application of vanadium coordinated with vanadium–1,2,4,5-benzenetetracarboxylic acid (V–BTCA) as an electrode material for hybrid supercapacitors has received little to no attention. To the best of our knowledge, the present work introduces V–BTCA, a novel potential electrode material for hybrid supercapacitor applications, and systematically compares its electrochemical behavior with vanadium sulfide (VS) and vanadium phosphate (VPO4). By evaluating these three vanadium-based materials under comparable experimental conditions in both three-electrode and two-electrode configurations, this study provides insight into how differences in material chemistry and electrode–device compatibility influence electrochemical performance. This comparative approach, therefore, addresses an important gap in the literature and provides a basis for the rational selection of vanadium-based materials for advanced hybrid energy-storage devices. The solvothermal method was followed for all three vanadium-based materials. Structural, morphological, and electrochemical characterizations were performed through Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The V–BTCA electrode delivered a specific capacity of 780 C g−1 at 0.8 A g−1, whereas the two-electrode-based hybrid device revealed maximum energy and power of 73.1 Wh kg−1 and 6800 W kg−1. A viable strategy toward the development of efficient SCs is demonstrated, offering comprehensive insights into multifunctional hybrid electrode architectures for energy storage.

2. Experimental section

2.1. Materials

Vanadium chloride (VCl3), 1,2,4,5-benzenetetracarboxylic acid (BTCA), sodium monosulfide trihydrate (Na2S·3H2O), sodium phosphate dibasic-dehydrate (Na2HPO4·2H2O), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), polyvinylidene fluoride (PVDF), acetylene black (AB), activated carbon (AC), potassium hydroxide (KOH), ethanol, and deionized (DI) water were used. All chemicals were procured from Sigma-Aldrich and Fisher Scientific and utilized as received without further purification. Nickel foam (Evonik Technology, Germany) was employed as the current collector for electrode fabrication. Electrochemical measurements were performed in a three-electrode configuration using a platinum (Pt) counter electrode and an Hg/HgO reference electrode on a Gamry ref. 3000 potentiostat/galvanostat (USA).

2.2. Synthesis of vanadium-based materials

V–BTCA, VS, and VPO4 were effectively synthesized via the solvothermal method, as shown in Fig. 1. For V–BTCA synthesis, a 0.5 M VCl3 solution (0.985 g) was prepared in 25 mL DI water and stirred for 30 min. Separately, 0.25 M BTCA ligand (0.955 g) was dissolved in a DI water and DMF mixture (18.75 : 6.25, v/v) under continuous magnetic stirring for 35 min. The VCl3 solution was then added dropwise to the BTCA solution over 25 min under continuous stirring. The prepared mixture was poured into a Teflon-lined stainless-steel autoclave and heated at 180 °C for 18 h. The resulting precipitate was collected by centrifugation, washed repeatedly with methanol and anhydrous ethanol, and oven-dried at 70 °C for 8 h. A similar synthesis procedure was followed for VS and VPO4. For VS, 0.4 M VCl3 solution (30 mL) and 0.8 M Na2S·3H2O solution (30 mL) were prepared separately in DI water/DMF and stirred for 20 min. For VPO4, 0.5 M VCl3 solution and 0.6 M Na2HPO4·2H2O solution were prepared separately in 20 mL of DI water/DMF mixture and stirred for 20 min. The respective precursor solutions were then mixed and subjected to the same solvothermal treatment. After centrifugation, washing, and drying, the VS and VPO4 powders were calcined at 400 °C for 5 h at a heating and cooling rate of 5 °C min−1.

Fig. 1. Schematic of the synthesis of V–BTCA, VS, and VPO4.

Fig. 1

Open in a new tab

2.3. Fabrication of slurry and electrodes

A homogeneous slurry was prepared by mixing 80% active material, 10% AB, and 10% PVDF as a binder. Subsequently, 30 µL of NMP was added as a solvent to achieve a uniform slurry.23 The mixture was magnetically stirred for 8 h. Prior to electrode fabrication, Ni foam (1 × 1 cm2) was cleaned by sonication in 1 M HCl for 15 min, followed by methanol, ethanol, and DI water for 10 min each. The cleaned Ni foam was then dried at 80 °C for 4 h, after which the prepared slurry was uniformly deposited onto the Ni foam and dried in a furnace at 75 °C for 7 h. For electrochemical testing, the electrodes consisted of a platinum wire counter electrode, Hg/HgO reference electrode, and V–BTCA, VS, and VPO4 working electrodes, respectively. All electrochemical analyses were performed in 1 M KOH electrolyte.

3. Results and discussion

3.1. Structural and morphological properties

The SEM analysis was performed to examine the surface texture of the prepared materials.24Fig. 2(a−c) shows the SEM images of solvothermally synthesized V–BTCA, VS, and VPO4 at a low magnification with a 2 µm scale bar. Fig. 2(a) indicates that V–BTCA exhibits irregular polyhedral and flake-like particles with rough surfaces and moderate agglomeration. The particles have fractured and wrinkled surfaces with relatively large interparticle pores. The SEM image of VS in Fig. 2(b) reveals a heterogeneous fibrous morphology with aggregated irregular particles and fine elongated structures. Short rod-like and flake-like features are also visible, with considerable interparticle spaces within the agglomerates. The SEM image of VPO4 in Fig. 2(c) shows a well-defined needle-like morphology with elongated crystalline structures. These needle-like structures form densely packed bundles with clear gaps between the particles, a relatively uniform size distribution, and good structural integrity. Furthermore, the elemental composition of the synthesized V–BTCA, VS, and VPO4 was verified by EDX analysis, as shown in Fig. 2(d–f). The EDX spectrum of V–BTCA displays prominent peaks of vanadium (V), carbon (C), and oxygen (O). Likewise, the VS spectrum shows characteristic peaks of vanadium (V) and sulfur (S). Similarly, the VPO4 spectrum reveals distinct peaks of vanadium (V), phosphorus (P), and oxygen (O), which confirms the elemental composition of the respective materials.25

Fig. 2. Morphological and elemental composition of V–BTCA, VS, and VPO4: (a–c) SEM images and (d–f) EDX elemental distributions.

Fig. 2

Open in a new tab

The crystalline nature of the synthesized V–BTCA, VS, and VPO4 was analyzed through XRD, and the corresponding patterns are shown in Fig. 3(a). The XRD pattern of V–BTCA showed well-defined diffraction peaks at 2θ values of 12.2°, 16.8°, 26.7°, 36.2°and 38.7°, indexed to planes (200), (220), (112), (113), and (110), which are aligned with previously reported metal-BTCA structures.26–28 These diffraction peaks verify the crystalline structure of V–BTCA. Similarly, the XRD pattern of the synthesized VS material indicates prominent diffraction peaks at 2θ values of 12.4°, 15.6°, 28.2°, 36.4°, and 38.1°, corresponding to the (100), (001), (002), (011), and (201) lattice planes, respectively. These reflections are consistent with the reported VS phase based on the JCPDS card (#36-1139) and JCPDS (#81-1521) and indicate the formation of a crystalline hexagonal VS phase.29 The high-intensity peaks show good crystallinity of VS samples. The XRD pattern of the synthesized VPO4 powder exhibits several distinct diffraction peaks at 2θ values of 26.1°, 28.3°, 31.6°, 33.4°, 49.5°, and 61.7° related to planes (−311), (−313), (310), (−222), (222), and (−134), confirming the crystalline nature of the material. The observed reflections are consistent with those reported for vanadium phosphate under JCPDS #01-072-2445 and support the formation of the VPO4 monoclinic phase.30

Fig. 3. Structural and chemical composition of V–BTCA, VS, and VPO4: (a) XRD patterns and (b) FTIR spectra.

Fig. 3

Open in a new tab

3.2. FTIR-based functional group analysis

FTIR analysis revealed the characteristic bond vibrations of samples, as shown in Fig. 3(b). The V–BTCA material shows a wide band from 3235 cm−1 to 3445 cm−1 attributed to O–H vibration modes. Bands analyzed in the range of 400−700 cm−1 signify V–O bond vibrations. Distinct bands at 1210 cm−1 and 1400 cm−1 are related to C Created by potrace 1.16, written by Peter Selinger 2001-2019 O groups and indicate asymmetric vibrations. Similarly, the peaks in the 800–1200 cm−1 region are associated with C–C bond vibrations within the benzene ring, along with the out-of-plane distortion stretching of C–H bending vibrations.31 The FTIR spectrum of VS displays bands centered at 3511 cm−1 and 1634 cm−1 corresponding to O–H bond vibrations. The bands between 500 cm−1 and 1000 cm−1 are related to the presence of strong V–S and S–V–S stretching. The band around 400 cm−1 is assigned to V–S stretching vibration.29 The FTIR spectrum of VPO4 presents a broad band between 3000 cm−1 to 3600 cm−1 related to O–H bonds from the adsorption of water and surface hydroxyl groups. The bands from 450 cm−1 to 650 cm−1 correspond to V–O–P and V–O bond vibrations, suggesting the presence of vanadium–oxygen bonding in the phosphate structure. The strong bands between 952 cm−1 and 1100 cm−1 correspond to P–O bond vibrations of the phosphate group.32 Overall, the combined XRD, FTIR, SEM, and EDX analyses confirm the successful formation of V–BTCA, VS, and VPO4 with distinct structural, chemical, and morphological characteristics. These differences provide a structural basis for the different electrochemical responses subsequently observed among the three vanadium-based electrodes.

3.3. Electrochemical characterizations

3.3.1. Three-electrode measurement

The electrochemical behavior of the three synthesized vanadium-based electrodes, V–BTCA, VS, and VPO4, was initially evaluated by CV in a three-electrode configuration using KOH electrolyte over a potential window of 0.0–0.7 V at various sweep rates from 3 to 50 mV s−1.33Fig. 4(a–c) displays the CV profiles of all fabricated electrodes, which demonstrate prominent anodic and cathodic peaks rather than the ideal rectangular behavior typical of capacitive electrode materials.34 The pronounced redox peaks indicate battery-like charge storage behavior, while the VS electrode shows higher current values and a larger area under the CV profile than V–BTCA and VPO4, consistent with the characteristics of metal sulfide-based electrode materials. However, VS suffers from poor structural stability and a lower specific surface area in the two-electrode configuration compared with V–BTCA and VPO4. Moreover, the expanded CV behavior of all three electrodes shows enhanced electrochemical characteristics and charge-storage capability, owing to their improved electronic transport and accessible electrochemical sites. Although the VS electrode showed the best performance in the three-electrode configuration, its electrochemical advantage was not fully retained in the assembled two-electrode configuration. In contrast, V–BTCA demonstrated comparatively superior performance due to its tunable structure, porosity, and metal-ion distribution. This result indicates the importance of electrode properties for assembling a device rather than three-electrode activity alone.

Fig. 4. CV profiles of (a) V–BTCA, (b) VS, and (c) VPO4 at various scan rates.

Fig. 4

Open in a new tab

Subsequently, GCD testing was executed within a potential range of 0.0–0.6 V across different current densities.35 All electrodes show non-linear GCD behavior with distinct voltage humps, as shown in Fig. 5(a–c). These voltage humps indicate that the charge-storage process is governed by reversible redox reactions characteristic of battery-grade materials, which also support the redox behavior observed in the CV analysis. The VS electrode displays a longer discharge time at high current densities, as compared to V–BTCA and VPO4, whereas V–BTCA and VPO4 offer prolonged discharge times at lower current densities. In addition, Qs values were computed from the GCD curves by applying the following expression:

3.3.1. 1

where Qs shows specific capacity (C g−1), I represents current, Δt is time of discharge, and m stands for mass loading of the fabricated materials. As current density increased, discharge time decreased for all electrodes because of limited ion diffusion at higher current densities as shown in Fig. 5(d). Among the three materials, VS exhibited the longest discharge time and a Qs of 1180 C g−1 at 3 A g−1, which reflects its superior electronic conductivity and rapid electron-transfer kinetics. In comparison, V–BTCA and VPO4 electrodes delivered a Qs of 730 and 470 C g−1 at 0.8 A g−1, respectively. Although the VS electrode demonstrated the best electrochemical performance in the three-electrode configuration, this superiority was not fully retained in the assembled two-electrode device. In contrast, V–BTCA exhibited comparatively better overall device performance, which indicates that device behavior depends on electrode compatibility and charge balance in addition to intrinsic three-electrode performance. To build upon the CV and GCD findings, EIS was carried out to evaluate the electron kinetics and ion transport behavior of V–BTCA, VS, and VPO4 electrodes in a frequency span of 0.1 Hz to 100 kHz, as shown in Fig. 5(e). The ESR, obtained from the intercept on the X-axis, was 0.55 Ω for V–BTCA, 0.27 Ω for VS, and 0.67 Ω for VPO4, respectively. The lowest ESR of VS indicates superior electrical conductivity, faster electron transport, and lower internal resistance compared with the other electrodes.36 Moreover, the steeper lowest-frequency area suggests effective ion diffusion and favorable charge-transfer kinetics, which is consistent with its enhanced CV response, prolonged GCD discharge time, and the highest specific capacity obtained in the three-electrode configuration.

Fig. 5. Comparative electrochemical characteristics of V–BTCA, VS, and VPO4: (a–c) GCD profiles at various current densities, (d) specific capacity at multiple current densities, and (e) Nyquist plots.

Fig. 5

Open in a new tab

3.3.2. Hybrid supercapacitor device evaluation

To evaluate the real-world application of V-BTCA, VS, and VPO4 electrodes, hybrid SC devices were assembled with these materials as the positive electrodes and AC as the negative electrode.37 As illustrated in Fig. 6(b), the AC electrode operates within a potential window of −1.0 to 0 V, whereas the V–BTCA, VS, and VPO4 positive electrodes operate within 0 to 0.7 V. Consequently, a wide operating voltage window of 0–1.7 V was selected for CV analysis.38 The CV profiles of the assembled devices were analyzed at multiple sweep rates ranging from 3 to 100 mV s−1 and are represented in Fig. 6(c–e). All devices exhibit broad quasi-rectangular CV profiles with weak redox humps, revealing that the ion-storage process is governed by the synergistic involvement of EDLC from the AC negative electrode and faradaic (battery-type) redox reactions of the positive electrode.6,39 As the voltage sweep rate increased, the current response increased proportionally while the CV profiles remained nearly unchanged, demonstrating rapid charge-transfer kinetics, efficient ion diffusion, and excellent structural stability. Among the three devices, V–BTCA//AC enclosed the largest CV area throughout the scan-rate range investigated, delivering the highest Qs of 650 C g−1, followed by VS//AC (580 C g−1) and VPO4//AC (210 C g−1) at 3 mV s−1. The improved electrochemical response of the V–BTCA//AC device may be associated with its accessible electroactive sites and favorable electrode–electrolyte interactions, which can facilitate ion transport and reversible redox reactions. Although the VS electrode exhibited the best three-electrode performance, the V–BTCA device demonstrated the highest storage capability, highlighting the importance of electrode compatibility and balanced charge storage in practical applications.40

Fig. 6. Electrochemical evaluation of HSC devices. (a) Schematic of the device, (b) comparative CV profiles of VPO4, VS, V–BTCA and AC at 3 mV s−1, and (c–e) CV curves of the corresponding devices at scan rates of 3–100 mV s−1.

Fig. 6

Open in a new tab

The GCD performance of electrodes in the HSC devices was evaluated over a voltage window of 0–1.6 V at current densities ranging from 0.8 to 8 A g−1, as depicted in Fig. 7(a–c). All devices exhibit non-linear charge/discharge profiles with broad voltage humps, confirming hybrid charge-storage characteristics. The Qs was calculated from GCD curves, as illustrated in Fig. 7(e). As the current density increased, the Qs gradually decreased due to limited ion diffusion at high rates. At 0.8 A g−1, the V–BTCA//AC, VS//AC and VPO4//AC devices delivered Qs of 310 C g−1, 282 C g−1 and 220 C g−1, respectively. V–BTCA//AC revealed superior performance relative to the other devices. Furthermore, energy and power are two vital parameters for evaluating the device effectiveness. To determine the energy density (Ed) in Wh kg−1 and power density (Pd) in W kg−1 of the HSC devices, the following equations were employed:

3.3.2. 2
3.3.2. 3

where Qs represents the specific capacity, ΔV signifies the potential window, and Δt is the discharge time (s). The V–BTCA//AC device exhibited the highest Ed of 73.1 Wh kg−1 at 0.8 A g−1, while a maximum Pd of 6800 W kg−1 was achieved at 8 A g−1. In comparison, the VS//AC and VPO4//AC devices obtained Ed of 66 Wh kg−1 and 56 Wh kg−1 at 0.8 A g−1, respectively, with both reaching a Pd of 6800 W kg−1 at 8.0 A g−1. Moreover, device stability is a crucial factor in analyzing the long-term cyclic life of the hybrid energy storage device. For this purpose, we tested all devices for 5000 continuous GCD cycles. Among the three devices, V–BTCA//AC maintained 92.83% capacity after the stability test, as shown in Fig. 8(a–c). Additionally, EIS was employed to evaluate the conductivity and internal resistance of the assembled HSC devices, as shown in Fig. 7(d). The V–BTCA//AC device exhibited the lowest ESR of 0.45 Ω, compared with 0.69 Ω for VS//AC and 0.82 Ω for VPO4//AC. The diminished semicircle indicates a negligible Rct, which shows improved charge-transfer performance of the fabricated hybrid device. A comparative analysis of recently reported studies and the current study is summarized in Table 1.

Fig. 7. Electrochemical characteristics of VPO4//AC, VS//AC and V–BTCA//AC: (a–c) GCD profiles, (d) Nyquist plots, and (e) specific capacity at various current densities.

Fig. 7

Open in a new tab
Fig. 8. Long-term cycling stability and energy storage performance of the assembled devices: (a–c) capacity retention over 5000 GCD cycles and (d–f) energy and power densities.

Fig. 8

Open in a new tab
Table 1. Comparison of specific capacity/capacitance, energy density, and power density of the fabricated device with recently reported literature values.
S. no. Hybrid device Specific capacity (Qs, C g−1) Energy density (Ed, Wh kg−1) Power density (Pd, W kg−1) Cyclic stability (%) Ref.
1 Sr–BTCA/PANI/NPG 645.5 74.5 3200 91.1 25
2 Ba–BTCA/Nd2O3 718 56.77 8000 92.0 26
3 Co–B–H–BTCA 172 42.5 4250 93.0 16
4 Mn-MOF@BTTC 627 25.0 532 91.0 17
5 Co–VS/G 1338 55.8 6100 88.9 12
6 NVS/G 862.2 64.7 5800 88.2 13
7 NiCo–P/Ni3V2O8 934 51.0 4800 84.21 14
8 NVP 441 46.0 3750 83.0 15
9 VPO4 460 56.0 6800 88.42 This study
10 VS 1550 66.0 6800 87.0 This study
11 V–BTCA 730 73.1 6800 92.31 This study
Open in a new tab

3.3.3. Charge storage kinetic analysis

Additionally, the power–law relationship between the peak current (i) and scan rate (v) was studied to determine the charge-storage kinetics.41 The relationship is expressed as:

i = avb 4

where “a” is a constant, and “b” is the kinetic parameter. The slope of the plot of log(i) versus log(v) represents the dominant charge-storage mechanism. A b-value of 0.5 represents battery-type behavior, while a b-value of 1.0 indicates capacitive behavior. Values between 0.5 and 1.0 indicate a hybrid charge-storage mechanism. Power–law analysis yielded b-values of 0.66–0.71 at 0.8–1.5 V, which fall within the range associated with a hybrid nature and confirm the coexistence of diffusion-controlled faradaic and surface-controlled capacitive contributions in the assembled hybrid devices, as shown in Fig. 9. The main observations obtained from the constructed hybrid devices demonstrate their potential as advanced electrode materials for energy storage applications.

Fig. 9. Analysis of charge storage in hybrid devices: log(i)–log(v) plots showing the corresponding b-values.

Fig. 9

Open in a new tab

4. Conclusion

This study presents a novel strategy for energy storage through three different synthesized materials derived from the same metal: V–BTCA, VS, and VPO4. SEM, EDX, XRD, and FTIR were used to investigate the morphological, elemental, structural, and chemical characteristics of the synthesized materials, respectively. Their electrochemical performance as electrode materials for hybrid devices was evaluated by three-electrode measurements through CV, GCD, and EIS analyses. CV and GCD results identified all three materials as battery-type electrode materials, with each material possessing high specific capacity. Hence, the synthesized materials demonstrate strong potential for HSC technology. Among the assembled devices, V–BTCA//AC exhibits superior Ed and Pd of 73.1 Wh kg−1 and 6800 W kg−1, respectively, along with the highest coulombic efficiency and capacity retention of 98.14% and 93%, respectively. Additionally, power-law analysis yielded b-values of 0.66–0.71, confirming the coexistence of diffusion-controlled faradaic and surface-controlled capacitive charge-storage contributions in the assembled HSC devices. The presented electrochemical features of V–BTCA establish its suitability as a candidate material for next-generation energy storage devices.

Author contributions

Conceptualization and writing – original draft (Taimoor Zada), data curation and methodology (Hafsa Naseer), formal analysis (Taimoor Zada, Yaseen Muhammad), funding acquisition (Usman Habib), investigation (Taimoor Zada, Usman Habib), project administration and resources (Usman Habib), software (Sana Azmat), supervision (Usman Habib), validation (Taimoor Zada, Saqib Javed), visualization and review and editing (Yaseen Muhammad).

Conflicts of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors gratefully acknowledge the University of Peshawar for providing FTIR characterization facilities.

Data availability

This article has no additional data. All data supporting this study are included in the article and are available from the first author upon reasonable request.

References

  1. Liu L. Zhang X. Liu Y. Gong X. Electrochemical energy storage devices–batteries, supercapacitors, and battery–supercapacitor hybrid devices. ACS Appl. Electron. Mater. 2025;7(6):2233–2270. doi: 10.1021/acsaelm.5c00069. [DOI] [Google Scholar]
  2. Muzaffar A. Basheer Ahamed M. Hussain C. M. Green supercapacitors: Latest developments and perspectives in the pursuit of sustainability. Renewable Sustainable Energy Rev. 2024;195:114324. doi: 10.1016/j.rser.2024.114324. [DOI] [Google Scholar]
  3. Zhang Y. Bao W. Jeffs E. Liu B. Han B. Mai W. Li X. et al., Unveiling the impacts of charge/discharge rate on the cycling performance of Li-metal batteries. ACS Energy Lett. 2025;10(2):872–880. doi: 10.1021/acsenergylett.4c03215. [DOI] [Google Scholar]
  4. Slater M. D. Kim D. Lee E. Johnson C. S. Sodium-ion batteries. Adv. Funct. Mater. 2013;23(8):947–958. doi: 10.1002/adfm.201200691. [DOI] [Google Scholar]
  5. Bejjanki D., and Kumar Puttapati S., Supercapacitor basics (EDLCs, pseudo, and hybrid), in Multidimensional Nanomaterials for Supercapacitors: Next Generation Energy Storage; Bentham Science Publishers, 2024, pp. 29–48 [Google Scholar]
  6. Kumar N. Lee S.-Y. Park S.-J. Bridging EDLC and pseudocapacitive mechanisms through materials design: recent advances in supercapacitor electrodes. Curr. Opin. Solid State Mater. Sci. 2026;41:101251. doi: 10.1016/j.cossms.2025.101251. [DOI] [Google Scholar]
  7. Chodankar N. R. Pham H. D. Kumar Nanjundan A. Fernando J. F. S. Jayaramulu K. Golberg D. Han Y.-K. Dubal D. P. True meaning of pseudocapacitors and their performance metrics: asymmetric versus hybrid supercapacitors. Small. 2020;16(37):2002806. doi: 10.1002/smll.202002806. [DOI] [PubMed] [Google Scholar]
  8. Ashritha M. G., and Hareesh K., Electrode materials for EDLC and pseudocapacitors, in Smart Supercapacitors, Elsevier, pp. 179–198, 2023 [Google Scholar]
  9. Iqbal M. Z. Abbasi U. Alam S. Recent progress of battery grade metal sulfides for hybrid energy storage devices. Int. J. Energy Res. 2022;46(4):3906–3938. doi: 10.1002/er.7481. [DOI] [Google Scholar]
  10. Kadyan P. Grover S. Sharma R. K. Review on biomass derived activated carbons as electrochemical electrode material for supercapacitor device. Curr. Mater. Sci. 2024;17(2):116–134. doi: 10.2174/2666145416666230314123738. [DOI] [Google Scholar]
  11. Osman A. I. Nasr M. Eltaweil A. S. Hosny M. Mohamed F. Al-Fatesh A. S. Rooney D. W. Abd El-Monaem E. M. Advances in hydrogen storage materials: harnessing innovative technology, from machine learning to computational chemistry, for energy storage solutions. Int. J. Hydrogen Energy. 2024;67:1270–1294. doi: 10.1016/j.ijhydene.2024.03.223. [DOI] [Google Scholar]
  12. Sandhu Z. A. Raza M. A. Awwad N. S. Ibrahium H. A. Farwa U. Ashraf S. Dildar A. Fatima E. Ashraf S. Ali F. Metal–organic frameworks for next-generation energy storage devices; a systematic review. Mater. Adv. 2024;5(1):30–50. doi: 10.1039/D3MA00822C. [DOI] [Google Scholar]
  13. Jha S. Qin Y. Chen Y. Song Z. Miao L. Lv Y. Gan L. Liu M. Ultralong-Life Zinc-Ion Hybrid Capacitors Enabled by Hydrogen-Bonding-Guided Nanosheet-Assembled Carbon Superstructures. ACS Sustain. Chem. Eng. 2025;13(50):21787–21800. doi: 10.1021/acssuschemeng.5c10802. [DOI] [Google Scholar]
  14. Qin Y. Hu C. Qi H. Lv Y. Song Z. Gan L. Liu M. Hydrogen-bonded interfacial super-assembly of spherical carbon superstructures for high-performance zinc hybrid capacitors. Nano-Micro Lett. 2026;18(1):38. doi: 10.1007/s40820-025-01883-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Li S. Zhang L. Xu B. Qin W. Wang M. Pan B. Liu H. Wang H. Combination of 1T-MoS2 and CuNi-MOF as an efficient lubricant additive. Colloids Surf., A. 2025;724:137486. doi: 10.1016/j.colsurfa.2025.137486. [DOI] [Google Scholar]
  16. Khan M. S. Alomar M. Al Huwayz M. Imran M. Jalalah M. Muhammad Afzal A. Diab M. A. Khalil S. Harraz F. A. Synergistic electrochemical performance of Mn-Li-S MOF integrated with PANI/rGO for supercapattery and hydrogen production applications. Micro Nanostruct. 2025:208367. doi: 10.1016/j.micrna.2025.208367. [DOI] [Google Scholar]
  17. Wang Y. et al., Enhancing energy storage via confining sulfite anions onto iron oxide/poly (3, 4-ethylenedioxythiophene) heterointerface. ACS Appl. Mater. Interfaces. 2023;15(51):59413–59421. doi: 10.1021/acsami.3c13148. [DOI] [PubMed] [Google Scholar]
  18. Peng Y. Jia X. Xu J. Jiao M. Yang B. Cao S. Zhang S. Pang H. Metal-organic framework (MOF) composites as promising materials for energy storage applications. Adv. Colloid Interface Sci. 2022;307:102732. doi: 10.1016/j.cis.2022.102732. [DOI] [PubMed] [Google Scholar]
  19. Theerthagiri J. Raja A. S. Nithyadharseni P. Lee S. J. Durai G. Kuppusami P. Madhavan J. Choi M. Y. Recent progress and emerging challenges of transition metal sulfides based composite electrodes for electrochemical supercapacitive energy storage. Ceram. Int. 2020;46(10):14317–14345. doi: 10.1016/j.ceramint.2020.02.270. [DOI] [Google Scholar]
  20. Pandit B. Rondiya S. R. Cross R. W. Dzade N. Y. Sankapal B. R. Vanadium telluride nanoparticles on MWCNTs prepared by successive ionic layer adsorption and reaction for solid-state supercapacitor. Chem. Eng. J. 2022;429:132505. doi: 10.1016/j.cej.2021.132505. [DOI] [Google Scholar]
  21. Li X. Xiao X. Li Q. Wei J. Xue H. Pang H. Metal (M= Co, Ni) phosphate based materials for high-performance supercapacitors. Inorg. Chem. Front. 2018;5(1):11–28. doi: 10.1039/C7QI00434F. [DOI] [Google Scholar]
  22. Mirghni A. A. Oyedotun K. O. Mahmoud B. A. Fasakin O. Tarimo D. J. Ncholu M. A study of Co-Mn phosphate supported with graphene foam as promising electrode materials for future electrochemical capacitors. Int. J. Energy Res. 2022;46(3):3080–3094. doi: 10.1002/er.7365. [DOI] [Google Scholar]
  23. Karim A. Ramzan M. Khalid W. Zahid R. Comparison of In Situ-Fabricated Ternary NiCoMn-Metal–Organic Frameworks versus Slurry Deposition on Porous Ni-Foam: A Facile Approach for Enhancing Supercapacitor Performance. Energy Technol. 2024;12(4):2301160. doi: 10.1002/ente.202301160. [DOI] [Google Scholar]
  24. Kumar R. Chugh R. Jabin S. Singh P. The Pivotal Role of Nanomaterials in Energy Storage Devices. ChemistrySelect. 2026;11(13):e07198. doi: 10.1002/slct.202507198. [DOI] [Google Scholar]
  25. Vasantha Kumar B. C., Madhu Kumar R., Shivarudrappa H. P., Santhosh B. M., and Prashantha Kumar P. N., Characterization methods for nanomaterials in energy storage, In Advanced Nanomaterials for Energy Storage Devices, Springer Nature Switzerland, Cham, 2024, pp. 57–76 [Google Scholar]
  26. Hammouda H. Abdelrahman G. Saleh E. A. M. Mahmud K. Iqbal M. Z. Kumar A. El-Aziz Kassem A. F. A. Alshik N. M. M. Oza A. D. Mohammed M. M. M. H. Study of interfacial synergy in strontium-based organic framework/polyaniline/nanoporous graphene ternary composite as positive electrode for battery-supercapacitor hybrid devices. RSC Adv. 2026;16(33):30017–30025. doi: 10.1039/D6RA01848C. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Shoukat W. Iqbal M. Z. Murtaza I. Kanjariya P. Rajiv A. Shit D. Albert H. M. Kumar Samal S. Kumar A. Wabaidur S. M. Optimizing hybrid supercapacitor performance through synergistic integration of metal–organic frameworks and metal oxides. RSC Adv. 2025;15(31):25221–25232. doi: 10.1039/D5RA00911A. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Zorainy M. Y. Mohamed S. Kaliaguine S. Mohamed G. Boffito D. C. Facile solvothermal synthesis of a MIL-47 (V) metal–organic framework for a high-performance Epoxy/MOF coating with improved anticorrosion properties. RSC Adv. 2022;12(15):9008–9022. doi: 10.1039/D1RA08950A. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Kalam N. A. Sengottaiyan C. Jayavel R. Ariga K. Shrestha R. G. Subramani T. Sankar S. Shrestha L. K. Vanadium sulfide/reduced graphene oxide composite with enhanced supercapacitance performance. J. Taiwan Inst. Chem. Eng. 2018;92:72–79. doi: 10.1016/j.jtice.2018.01.040. [DOI] [Google Scholar]
  30. Chiweshe T. T. Fusion–extraction technique of vanadium (III) using ammonium phosphate salt as flux. Crystals. 2022;12(10):1464. doi: 10.3390/cryst12101464. [DOI] [Google Scholar]
  31. Iqbal M. Z. Khan M. W. Shaheen M. Sharif S. Wabaidur S. M. Ansari M. Z. Aftab S. 1, 2, 4, 5-benzene-tetra-carboxylic acid and 2-methylimidazole bi-linker intercalated redox active copper organic framework for advanced battery-supercapacitor hybrids. J. Electroanal. Chem. 2023;941:117505. doi: 10.1016/j.jelechem.2023.117505. [DOI] [Google Scholar]
  32. Mei P. Kaneti Y. V. Pramanik M. Takei T. Dag Ö. Sugahara Y. Yamauchi Y. Two-dimensional mesoporous vanadium phosphate nanosheets through liquid crystal templating method toward supercapacitor application. Nano Energy. 2018;52:336–344. doi: 10.1016/j.nanoen.2018.07.052. [DOI] [Google Scholar]
  33. Zhu J. Chen B. Ni M. Xu H. A mini-review on three-electrode configuration for Solid Oxide Cells. Energy Rev. 2025;4(2):100128. doi: 10.1016/j.enrev.2024.100128. [DOI] [Google Scholar]
  34. Dubal D. P. Omar A. Ruiz V. Gomez-Romero P. Hybrid energy storage: the merging of battery and supercapacitor chemistries. Chem. Soc. Rev. 2015;44(7):1777–1790. doi: 10.1039/C4CS00266K. [DOI] [PubMed] [Google Scholar]
  35. Nare R. K. Ramesh S. Kumar Basavi P. Kakani V. Bathula C. Yadav H. M. Babu Dhanapal P. Krishna Reddy Kotanka R. Rao Pasupuleti V. Sonication-supported synthesis of cobalt oxide assembled on an N-MWCNT composite for electrochemical supercapacitors via three-electrode configuration. Sci. Rep. 2022;12(1):1998. doi: 10.1038/s41598-022-05964-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Perdana M. Y. Bashir A. J. Abdallah M. Emdad Hossain M. Abdul Aziz M. Turki N. B. Qasem A. D. Understanding the behavior of supercapacitor materials via electrochemical impedance spectroscopy: a review. Chem. Rec. 2024;24(5):e202400007. doi: 10.1002/tcr.202400007. [DOI] [PubMed] [Google Scholar]
  37. Li Z. Bai S. Chen K. Liu Y. Zhang Y. Liu S. Polyaniline packed activated carbon as pseudocapacitive negative electrodes. Chem. Eng. J. 2024;481:148486. doi: 10.1016/j.cej.2023.148486. [DOI] [Google Scholar]
  38. Ahmad M. Nawaz T. Hussain I. Amara U. Chen X. Eddahani Y. Walia R. Zhang K. Expanding the potential window through synergistic design and oriented heterostructure for supercapacitor. Small Methods. 2025;9(4):2401239. doi: 10.1002/smtd.202401239. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Aziz S. B. Hama P. O. Aziz D. M. Sadiq N. M. Woo H. J. Kadir M. F. Z. Abdulwahid R. T. Al-Asbahi B. A. Ahmed A. A. A. Jamal H. EDLC supercapacitor with enhanced charge-discharge cycles designed from plasticized biopolymer blend electrolytes: Biomaterials will be the future of energy storage devices. J. Energy Storage. 2025;114:115841. doi: 10.1016/j.est.2025.115841. [DOI] [Google Scholar]
  40. Olabi A. G. Abbas Q. Ahmed A. M. Ali Abdelkareem M. Supercapacitors as next generation energy storage devices: Properties and applications. Energy. 2022;248:123617. doi: 10.1016/j.energy.2022.123617. [DOI] [Google Scholar]
  41. Afzal A. M. Muzaffar N. Iqbal M. W. Dastgeer G. Manzoor A. Razaq M. Wabaidur S. M. Al-Ammar E. A. Eldin S. M. Exploring the charge storage mechanism in high-performance Co@ MnO2-based hybrid supercapacitors using Randles–Ševčík and Dunn's models. J. Appl. Electrochem. 2024;54(1):65–76. doi: 10.1007/s10800-023-01939-3. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

This article has no additional data. All data supporting this study are included in the article and are available from the first author upon reasonable request.

Articles from RSC Advances are provided here courtesy of Royal Society of Chemistry

RESOURCES