Figure 2(a) displays Energy-Dispersive X-ray Spectroscopy (EDAX) of the prepared BCA material. The EDAX spectrum shows the presence of two prominent elements, carbon (C) and oxygen (O). These elements are clearly indicated by the peaks in the EDAX spectra. The atomic weight percentage of these elements are provided in the spectrum. The information confirms the relative abundance of carbon and oxygen in the material. The presence of carbon as a major component is significant, especially in the context of the activated carbon materials. Based on the elemental composition and the atomic weight percentages provided in the EDAX spectrum, it can be concluded that the prepared material is consistent with the characteristics expected for the activated carbon. From the scanning electron microscope (SEM) images displayed in Fig. 2(b,c,d), it is evident that distinct mono-structures have been observed at different magnifications. The magnification levels range from 50 µm (Fig. 2b), 30 µm (Fig. 2c) and 20 µm (Fig. 2d). At the lowest magnification of 50 µm, cubic-sphere are clearly visible and have been highlighted in yellow in the image. The presence of cubic-spheres is a notable characteristics of the micro-structure observed on the image. At a higher magnification of 30 µm, a distinct flower-like morphology becomes apparent. This morphology is characterized by the formation of multiple cubic-spheres that cluster together, giving rise to the overall flower-like structure. The cubic-sphere morphology, as observed in Fig. 2 (b) is still evident within its larger structure. At an even higher magnification of 20 µm, the intricate details of the flower-like morphology with the embedded cubic-spheres are prominently visible. The presence of cubic-spheres within the flower-like structure is clearly seen, further emphasizing their role in the forming this complex microstructure. The successful formation of cubic-spheres with highlighted pores (in red color) is a significant achievement. These pores have been created through a synergistic effect involving KOH carbonization and activation processes. The pores act as pathways that enable the efficient movement of electrolyte ions into the material’s interior [9]. This enhanced accessibility to electrolyte ions is instrumental in improving the material’s charge-storage capacity. The increased surface area and porosity resulting from the pore formation significantly contribute to the material’s capacity to store electrical charge effectively. This property is highly desirable and recommended for the performance of SCs. The synergy between KOH carbonization and activation processes is essential in creating these desirable pore structures. The combination of these processes has led to the formation of cubic-spheres with well-defined pores, optimizing the material’s performance for SC applications [10].
The transmission electron microscopy (TEM) images displayed in the Fig. 2(d) and (e) provide a deeper insight into the surface morphology of the prepared BCA material. In the Fig. 2(d) and Fig. 2(e), clumps or aggregates of nano-sphere are clearly visible. These nano-spheres are indicative of the structural features present within the material. Their presence suggests a well-defined and organized arrangement of nano-scale particles. The edges of the nano-sphere exhibit partial graphitization. This means that certain regions of the material have undergone a graphitization process, resulting in the formation of graphitic carbon structures. Graphitization is known to enhance the electrical conductivity and stability of the carbon-based materials [6]. The TEM images reveal an interlayer spacing within the material and this spacing is highlighted in Fig. 2(f). The spacing between these layers is approximately 0.3 nm. Such interlayer spacing is a characteristic property of the prepared BCA and is often associated with the crystalline structure of carbon material [8].
The Raman spectroscopy analysis conducted on the as-prepared BCA material in Fig. 3(a) provides valuable information about the material's crystal structure and graphitic nature. [10]. The Raman spectrum exhibits two significant bands, known as the D band and the G band. These bands are essential for characterizing the ordered and disordered levels of the material's crystal structure. The D band (~ 1350 cm− 1) is associated with disordered carbon structures and defects within the material. Its intensity is indicative of the degree of disorder and the presence of defects. The G band (~ 1580 cm− 1) represents the graphitic nature of the material. The intensity and shape of the G band provide insights into the material's crystallinity. The intensity of the D and G bands is known to correspond to the edge chirality of the carbon structures within the material. This sensitivity makes Raman spectroscopy a powerful tool for assessing the size and defects of carbon-based materials [11]. The spectrum reveals the presence of a broader secondary D peak (2D band) at ~ 2500 cm − 1. The 2D band is often associated with multi-layer graphene-like structures and provides additional information about the material's graphitic properties [9]. The ID/IG ratio is calculated from the intensities of the D and G bands. In this case, the calculated ID/IG value is 0.83. A high ID/IG ratio suggests the presence of multi-layer graphene-like structures, which is consistent with the observed 2D band. The presence and intensity of the D and G bands, as well as the 2D band and ID/IG ratio, provide insights into the degree of disorder, defects, and multi-layer graphene-like structures within the material.
The FTIR (Fourier-Transform Infrared) spectrum presented in Fig. 3(b) offers valuable insights into the surface functional groups of the as-prepared BCA material. A broad peak centered on ~ 3273 cm− 1 is observed in the spectrum. This peak is associated with the vibrations of the O-H group, which can originate from both water molecules and compounds containing alcohol groups like resorcinol. A lower-intensity peak, appearing as a hump-like feature around ~ 2900 cm− 1, is attributed to C-H stretching vibrations. It suggests the presence of various carbon-hydrogen (C-H) bonds, including -CH, -CH2, and -CH3 groups. A distinct peak at ~ 1629 cm− 1 corresponds to the stretching vibration of the carboxylic acid functional group (C = O). This group is commonly found in organic compounds and contributes to the material's chemical properties. Another peak at ~ 1026 cm− 1 indicates the presence of the C-O functional group. C-O bonds are often associated with compounds like alcohols, ethers, and esters. The peak at ~ 661 cm − 1 is related to the stretching vibration of C-H bonds in an out-of-plane configuration. This band provides information about specific carbon-hydrogen bonds within the material [11–12].
The X-ray diffraction (XRD) spectrum presented in Fig. 3(c) provides insights into the crystalline nature of the as-prepared BCA material. A pronounced peak at around ~ 25° in the XRD spectrum corresponds to the (002) plane of the material. This peak suggests the presence of amorphous or disordered regions within the material. Amorphous regions lack the long-range ordered atomic structure found in crystalline materials. Another peak is observed at around ~ 45°, indicating the presence of a (100) plane in the material. This peak is characteristic of the graphitic nature of the material, suggesting the presence of regions with a more ordered and crystalline atomic arrangement. The presence of both a graphitic peak and an amorphous peak in the XRD spectrum indicates that the as-prepared BCA material exhibits a coexistence of crystalline and amorphous phases. This suggests a heterogeneous structure with regions of varying degrees of order. Notably, the intensity of the graphitic peak is lower compared to the amorphous peak. This difference in intensity implies that the amorphous phase dominates within the material, while the graphitic phase is present but in smaller proportions. This observation reinforces the conclusion that the material primarily possesses an amorphous nature [12–13].
Figure 3(d) illustrates the N2 adsorption-desorption isotherm of the prepared BCA material, while Fig. 3(e) depicts the corresponding pore-size distribution (PSD) curve. These analyses provide crucial information about the material's porosity and surface area, which have a significant impact on its electrochemical performance [13]. The N2 adsorption-desorption isotherm exhibits a Type IV BET isotherm. This type of isotherm is characteristic of materials with well-developed meso-pores and capillary condensation. It indicates that nitrogen gas is being adsorbed into the material's meso-pores, supporting the existence of a porous structure [14]. The capillary condensation observed in the isotherm is associated with the presence of meso-pores. This finding aligns with what was observed in the SEM images, confirming the existence of meso-pores in the material. The specific surface area of the as-prepared BCA material is determined to be approximately ~ 1299 m2g− 1. This high surface area is noteworthy and is known to have a significant impact on the electrochemical performance of the material. A larger surface area provides more active sites for electrochemical reactions, making it advantageous for supercapacitor electrode materials [15]. The PSD curve reveals distinct peaks around ~ 1–3 nm, indicating the presence of both micro and meso-pores within the material [16]. This observation aligns well with the information obtained from SEM images and the Type IV BET isotherm. The combination of a high specific surface area (~ 1299 m2g− 1) and the presence of micro and meso-pores in the BCA material suggests that it is well-suited for use as a supercapacitor electrode material. The abundant surface area and the porous structure provide ample sites for electrolyte ion adsorption and efficient charge storage, enhancing its electrochemical performance [15–16].
Figure 3(f) apparently shows a carbon profile (C1s) of X-ray Photoelectron Spectroscopy (XPS) spectrum for the as-prepared BCA material. There is a prominent peak at 284 eV in the C1s spectrum. This peak is attributed to the reduction of oxygen functionalities within the carbonaceous material due to thermal annealing treatment. Additionally, the peak suggests a specific type of chemical bonding or electronic state within the carbon atoms of the material. The fact that this peak is attributed to the reduction of oxygen functionalities implies that the thermal annealing treatment led to the removal or transformation of oxygen-containing groups or bonds within the material. The peak at 284 eV is associated with the C-C/C = C bond. This means that it represents carbon atoms bonded to other carbon atoms, possibly in the form of single bonds (C-C) or double bonds (C = C). This information can provide insights into the structural changes occurring in the carbonaceous material during the thermal annealing process.
The role of a dual-redox active electrolyte (composed of KBr and MVCl2) in contributing to the pseudo-capacitance and redox reaction (formation of MV2+/MV+ redox couple) of the electrode material at the electrode-electrolyte interface have been investigated [15]. We conducted an investigation involving various molar concentrations, ranging from 1M to 5M, and 0.1M to 0.3M of both pristine redox electrolytes, KBr and MVCl2, to assess their respective contributions to capacitance. Furthermore, we evaluated the ionic conductivity of these redox electrolytes at different molar concentrations, including KI and KBr. The results of these ionic conductivity assessment have been documented in Fig. 4(a). Notably, the findings indicate that the KBr exhibits superior ionic conductance in comparison to the electrochemical performance of BCA when immersed in a KI redox electrolyte.
Figure 4 (b) illustrates the CV performance of the BCA electrode material when subjected to different electrolytes. In this case, the two key electrolytes under investigation are KOH and single-redox electrolyte additive, specifically KI and KBr. The CV curve provides a graphical representation of how the current changes concerning the voltage. This is a crucial measurement to assess the electrochemical behaviour of the electrode material and its suitability for SC applications [16]. From the CV curves, it is seen that KBr additive led to the highest current among the tested electrolytes. This observation suggest that KBr has a significant positive impact on the electrochemical performance of the BCA material, making it a preferred choice as the redox electrolyte for the SC device. In essence, the selection of KBr as the redox-active electrolyte as the additive for the SC device, demonstrates its superior electrochemical performance compared to the other electrolyte options, such as KOH and KI. This choice is likely to enhance the overall performance and efficiency of the SC device.
Figure 4(c) illustrates the CV analysis performed on the as-prepared BCA material while immersed in a 0.4 M KBr electrolyte solution, employing a sweep rate of 50 mVs− 1. The experiment covers a wide voltage range encompassing both positive and negative sides. Specifically, the positive potential region spans from 0 to 0.4 V, while the negative potential region ranges from − 1.2 V to 0 V. Consequently, the entire voltage window, known as the full potential window, amounts to 1.8 V for the Supercapacitor (SC) device under investigation. Within this experimental setup, the positive potential range reveals Electric Double-Layer Capacitance (EDLC) behavior, showcasing charge storage primarily through the formation of electric double layers at the electrode-electrolyte interface. In contrast, the negative potential range demonstrates pseudo-capacitance behavior, indicating redox reactions occurring at the same interface, contributing significantly to charge storage [17]. The distinguished outcome from the CV curves is the pronounced influence of the KBr redox-active additive, which is evident mainly within the positive potential range. In this context, the KBr additive, when incorporated into the alkaline electrolyte (6M KOH), substantially enhances the EDLC behavior at the positive potential side of the voltage window.
After introducing a single redox additive to the alkaline electrolyte solution, we proceeded to incorporate another redox-active substance, MVCl2, into the same alkaline-based electrolyte. The CV profiles for these configurations were recorded at a scan rate of 50 mVs− 1, and these profiles are presented in Fig. 4 (d). Notably, a redox peak emerged on the negative side of the CV curve. Consequently, when cyclic voltammetry was conducted over the entire potential range, this redox peak persisted, contributing significantly to the pseudo-capacitance. Additionally, there was an observed increase in current on the positive side of the CV curve.
The redox peak confirms the possible valence state to be MV0/MV+ and MV+/MV2+. The following are the redox reactions which are reversible and are associated with the generated pseudo-capacitance [16].
MV2+ + e− ⌠ MV+ (1)
MV+ + e− ⌠ MV0 (2)
The presence of reversible redox processes within the redox-mediated alkaline-based electrolytic solution serves as confirmation of the existence of pseudo-capacitive behavior, as elucidated in reference [17]. This pseudo-capacitive behavior arises from the Faradaic reactions facilitated by the redox-additive electrolyte. It is evident that the incorporation of the dual-redox electrolyte (comprising KBr and MVCl2) has led to an increase in the current on both the positive and negative sides of the potential.
Figure 5(a) illustrates the GCD of the BCA electrode prepared under various electrolyte conditions, encompassing both positive and negative potential ranges. The operating potential window was maintained consistently across all three electrolytes: KOH, KOH with KBr, and KOH with KI. This investigation aims to determine which electrolyte exhibits higher redox activity by comparing KI and KBr. The results from the GCD analysis indicates that KBr consistently leads to longer discharge times in comparison to the other electrolytes. The variations in the slope of the discharge curve, observed when introducing the redox-active electrolyte into the alkaline environment, contribute to the generation of pseudo-capacitance [17]. Specifically, the noticeable deviation in slope in the case of the single-redox-active electrolyte is the underlying reason for the extended discharge duration.
In Fig. 5(b), we present the GCD profile of the as-prepared BCA electrode, which incorporates a dual-redox additive consisting of both KBr and MVCl2, introduced into an alkaline medium. This analysis encompasses both charging and discharging processes conducted over both positive and negative potential ranges. Furthermore, a comprehensive evaluation is performed over the entire potential spectrum. Remarkably, when employing the dual-redox electrolyte in the alkaline medium, the charging and discharging times exhibit a remarkable level of similarity, and the associated voltage drop (IR drop) is notably reduced. This observation suggests that the dual-redox electrolyte displays enhanced performance in terms of conductivity compared to a scenario where only a single redox additive is incorporated. The GCD curves underscore that the dual-redox electrolyte configuration yields higher electrical conductivity compared to a setup where only a single redox additive is introduced, highlighting the promising potential of this dual-redox system in enhancing the electrochemical performance of the alkaline medium [16–17].
Figure 5(c) provides a visualization of the GCD profiles for the as-prepared electrode material immersed in a dual-redox electrolyte composed of KBr and MVCl2, within an alkaline medium (KOH). These GCD experiments were conducted under various current density conditions, ranging from 1 to 10 Ag− 1, with the intention of evaluating the rate capacity of the supercapacitor. Evidently, at a current density of 1 Ag− 1, the GCD curve demonstrates a significantly extended discharge period when compared to the lower current density settings. This prolonged discharge time at 1 Ag− 1 is indicative of the dual-redox electrolyte's exceptional ionic conductivity and its capacity to facilitate ion diffusion within the system. This improvement in ionic conductivity and ion diffusion directly contributes to enhancing the overall capacity of the supercapacitor, as described in reference [18]. Furthermore, even when subjected to higher current densities, the GCD profiles maintain highly symmetrical shapes, indicating the robustness and stability of the system under varying rates of charge and discharge. This observation highlights the potential of the dual-redox electrolyte configuration for effectively addressing the rate capacity requirements of the supercapacitor.
Figure 5(d) provides a comprehensive overview of the specific capacitances obtained through calculations based on the GCD curves. These calculations were performed under identical conditions, specifically at a current density of 1 Ag− 1, for various different electrolytes. A distinguished trend emerges from the data. Notably, the dual-redox electrolyte, denoted in blue, exhibits a remarkable three-fold increase in specific capacitance compared to the single redox-based electrolytes, namely KI and KBr. This substantial enhancement in specific capacitance underscores the superior electrochemical performance achieved by the dual-redox electrolyte configuration [16]. In contrast, the single redox-based electrolytes, KI and KBr, demonstrate relatively similar specific capacitance values within a comparable range. This observation emphasizes the distinctive advantage of incorporating a dual-redox system, as it significantly boosts the specific capacitance, making it an attractive choice for applications where higher energy storage capacity is a critical requirement.
The specific capacitance of the dual-redox based electrolyte, which consists of KOH with KBr and MVCl2, has been calculated based on the GCD curve data collected under varying current density conditions, as illustrated in Fig. 5(e). These calculations serve to characterize how the specific capacitance of the system responds to different rates of charge and discharge. At a relatively low current density of 1 Ag− 1, the dual-redox electrolyte demonstrates its highest specific capacitance, achieving an impressive value of approximately 887 Fg− 1. This notable capacitance level reflects the capacity of the system to efficiently store electrical energy under these conditions. However, as the current density is increased to a higher current density of 10 Ag− 1, there is a reduction in the specific capacitance. Specifically, the specific capacitance diminishes from its initial value of approximately 887 Fg− 1 to around 56 Fg− 1 at the higher current density of 10 Ag− 1. This decrease in specific capacitance at higher current densities is a common behaviour observed in supercapacitors and can be attributed to factors such as limited ion diffusion and increased internal resistance at higher charge and discharge rates [18].
Figure 5(f) provides a graphical representation of the EIS conducted on the as-prepared BCA material in the presence of various electrolytes, measured within a specific frequency range of 1500 Hz. This analysis offers valuable insights into the electrical behaviour and performance of the electrode material when exposed to different electrolyte conditions. Upon close examination of the EIS spectrum results, a notable trend emerges. Specifically, the dual-redox based electrolyte stands out as having the lowest resistance among the tested electrolytes. This observation suggests that the dual-redox electrolyte significantly enhances the electrical conductivity of the electrode material. The lower resistance signifies that ions can move more freely within the system, resulting in improved electrical performance [19–20]. This finding further strengthens the choice of the dual-redox electrolyte as an effective component in this electrochemical system. It aligns with and corroborates the findings of other electrochemical assessments, reinforcing the notion that this particular electrolyte configuration is indeed an excellent selection for achieving the desired electrochemical properties.
The GCD profiles for two distinct electrolytes, namely the dual-redox electrolyte (KBr/MVCl2) and the pristine single-redox electrolyte (KBr), were investigated under constant voltage conditions ranging from 0 to 1.8V, at varying current densities ranging from 1 to 10 Ag− 1. This investigation is presented through Fig. 6(a) and 6(b). The experiments were conducted using a two-electrode cell configuration system, specifically the CR 2032 setup. In both cases, as depicted in the graphs, the GCD curves initially exhibit a linear behavior up to 1.0V. However, beyond 1.0V and up to 1.2V, there is a noticeable deviation in the slope before the curves return to a linear trajectory. This deviation in slope is attributed to the ionic contribution of chloride ions from MVCl2 and bromide ions from KBr, which influence the electrochemical behavior, as referenced in [20]. The presence of this additional ionic contribution from the dual-redox electrolyte is associated with a prolonged charging and discharging process, as noted in [21].
To further analyze the individual charge and discharge characteristics, we provide a visual representation of the GCD for BCA in single- and dual-redox electrolytes in Fig. 6(c) and 6(d), respectively. Notably, the charging and discharging times are remarkably similar, and the voltage drop across the internal resistance (IR drop) is approximately ~ 0.015V. This finding highlights the superior conductivity of the redox-based electrolyte.The columbic or capacitance efficiency of the dual-redox electrolyte is estimated to be around 90%, demonstrating its efficient utilization of stored energy. Furthermore, the dual-redox electrolyte boasts an extended time limit, with discharge times reaching ~ 4500 seconds, far surpassing the ~ 2000 seconds observed with the pristine single-redox electrolyte. Importantly, there is no significant IR drop evident in these profiles. The extended discharge time provided by the dual-redox electrolyte is a testament to its exceptional ionic conductivity, confirming its outstanding electrochemical performance, as emphasized in [26].
The study involves investigating the life cycle management of the dual-redox based electrolyte through degradation analysis. To provide a basis for comparison, a similar characterization testing is conducted on a single-redox additive electrolyte. The charging and discharging processes are executed within a two-electrode system, encompassing 10,000 cycles at a current density of 1 Ag− 1, as illustrated in Fig. 7(a). In the case of the single-redox electrolyte, the specific capacitance exhibits initial stability, persisting until approximately 1000 cycles. Subsequently, a decline in specific capacitance is observed. However, stability begins to recover after surpassing 4000 cycles, ultimately resulting in an impressive ~ 80% capacitance retention over the entire 10,000 cycles. In contrast, when examining the dual-redox electrolyte, it becomes evident that the system displays greater stability from the outset compared to the single-redox counterpart. Additionally, the specific capacitance remains relatively consistent over the testing period. This consistency can be attributed to the delayed interaction and migration of MVCl2 at the electrode-electrolyte interface, as described in references [27–29]. Remarkably, the dual-redox electrolyte system (KBr/MVCl2) achieves an impressive ~ 93% specific capacitance retention at 1 Ag− 1 over the course of 10,000 charge-discharge cycles. These results clearly demonstrate that the incorporation of Methyl Viologen chloride as a secondary additive in the electrolyte system not only enhances capacitance but also maintains its stability throughout the extensive 10,000-cycle testing period.
Figure 7(b) serves as a visual representation of the rate performance of both single and dual-redox based electrolytes in the context of supercapacitor applications. To assess their performance, specific capacitance values were determined, with the highest specific capacitance values being approximately ~ 196 Fg− 1 for the single-redox electrolyte (KBr) and ~ 560 Fg− 1 for the dual-redox electrolyte (KBr/MVCl2), both measured at a current density of 1 Ag− 1. The dual-redox electrolyte, with the incorporation of KBr/MVCl2, exhibits a remarkably enhanced specific capacitance, approximately three times that of the single-redox electrolyte (KBr). This substantial increase in specific capacitance signifies the superior energy storage capacity of the dual-redox system, underscoring its potential for high-performance supercapacitors [20–21].
To evaluate the overall performance of the fabricated symmetric supercapacitor (SC), parameters such as energy and power densities are taken into consideration. These metrics provide a comprehensive understanding of how efficiently the supercapacitor can store and deliver electrical energy, further confirming the advantages of the dual-redox electrolyte configuration in enhancing the supercapacitor's energy storage capabilities. In Fig. 7(c), we observe a plot showcasing the delivered energy and power density characteristics of both single and dual-redox electrolytes in the context of their application in supercapacitors. As is commonly observed, there exists an inverse relationship between power density and energy density: as power density increases, energy density tends to decrease. The highest values for energy density and power density are particularly noteworthy. Specifically, the dual-redox based electrolyte (KBr/MVCl2) demonstrates an impressive energy density of approximately ~ 77 Whkg− 1 at 1 Ag− 1, and an outstanding power density of approximately 3874 Wkg− 1 at a higher current density of 10 Ag− 1. These results unequivocally establish the dual-redox electrolyte as a standout performer, particularly suited for high-performance supercapacitor applications. The combination of elevated energy density and remarkable power density highlights the potential of this dual-redox system to deliver efficient energy storage and rapid energy release, making it a promising candidate for demanding applications where both high energy and power outputs are essential.
The evaluation of ionic resistance and conductance in the constructed device was conducted using the EIS technique, and the outcomes are presented in Fig. 7(d). This technique provides insights into the charge-transfer characteristics of the device. In particular, the charge-transfer resistance (Rct) was determined for both the dual and single-redox electrolytes, yielding values of approximately ~ 10 Ω and ~ 13 Ω, respectively. It's important to note that lower resistance values correspond to higher ionic conductance within the system [30]. The noteworthy finding here is that the dual-redox electrolyte demonstrates significantly lower resistance compared to the single-redox electrolyte. This outcome underscores the superior ionic mobility and conductance of the dual-redox system, corroborating the results obtained from other electrochemical assessments performed in both two-electrode and three-electrode configuration. The reduced resistance exhibited by the dual-redox electrolyte aligns with its enhanced electrochemical performance, indicating its potential for improved charge transfer and ion mobility within the supercapacitor system. These findings collectively support the superiority of the dual-redox electrolyte over the single-redox counterpart in various electrochemical measurements.
The electrochemical performance of BCA in the dual-redox active electrolyte has been assessed and compared with recently reported single and dual-redox-based electrolytes intended for supercapacitor (SC) applications. The results of this comparative analysis are summarized in Table 1.Various redox additives, including potassium bromide (KBr), potassium iodide (KI), Hydroquinone (HQ), HQ with p-phenylenediamine (PD), viologen bromide, and potassium ferri-cyanide, have been employed and investigated in these different electrolyte configurations. It's worth noting that in most cases, these redox additives are introduced into acidic and neutral electrolytes. Alkaline electrolyte mediums, where only redox additives are incorporated, are relatively rare in the literature. Table 1 serves as a valuable resource for researchers and practitioners in the field of supercapacitor development, providing insights into the comparative performance of different redox additives and electrolyte combinations. This information aids in making informed decisions regarding the selection of appropriate electrolytes for specific supercapacitor applications, considering factors such as electrochemical performance, stability, and redox activity.
Table 1
Comparison of supercapacitor performance of BCA in redox –active electrolytes with carbon electrodes reported previously in the literature
Electrode | Redox Additive | Electrolytic Medium | Specific Capacitance (Fg− 1) | Energy Density WhKg− 1 | Power Density WKg− 1 | No. of Cycles | Capacitance Retention (%) | Reference |
Graphite-based AC | KBr | Na2SO4 | 127 | 57.15 | 5262 | 10000 | 82.8 | [22] |
Biomass-derived AC | KI + HQ | H2SO4 | 186 | 8 | 750 | 5000 | 98 | [23] |
Commercial AC | HQ + PD | H2SO4 | 116.23 | 1.85 | 1500 | 2000 | 83 | [24] |
Commercial AC | Potassium Ferri-cyanide | KOH | 142 | 7.07 | 2999 | NA | NA | [25] |
BCA | KBr/MVCl2 | KOH | 560 | 77 | 3874 | 10,000 | 93 | Present Work |