Next Article in Journal
Intrinsic Thermal Stability of Li-Rich Mn-Based Cathodes Enabling Safe High-Energy Lithium-Ion Batteries
Previous Article in Journal
Referential Integrity Framework for Lithium Battery Characterization and State of Charge Estimation
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Exploring the Potential of Green Synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 Using Orange and Lemon Extracts for Hybrid Supercapacitor Applications

1
Centre of Excellence in Solid State Physics, University of the Punjab, Quaid-e-Azam Campus, Lahore 54590, Pakistan
2
Institute of Metallurgy and Materials Engineering, University of the Punjab, Lahore 54590, Pakistan
3
Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
4
Institute of Physics and Technology, Ural Federal University, Yekaterinburg 620002, Russia
5
Department of Physics and Technical Sciences, Western Caspian University, Baku AZ1001, Azerbaijan
6
Computer Engineering Department, Faculty of Engineering and Natural Sciences, Istunye University, Istanbul 34396, Turkey
7
Department of Engineering Sciences, University of Agder, 4879 Grimstad, Norway
8
Department of Physics, University of Engineering and Technology, Lahore 54590, Pakistan
*
Authors to whom correspondence should be addressed.
Batteries 2025, 11(8), 310; https://doi.org/10.3390/batteries11080310
Submission received: 24 June 2025 / Revised: 7 August 2025 / Accepted: 9 August 2025 / Published: 15 August 2025
(This article belongs to the Section Supercapacitors)

Abstract

Supercapacitors are required to store energy from renewable resources to ensure a pollutant-free environment. To further encourage its study, researchers are interested in introducing green methods to produce electrode materials. Green synthesis is an innovative and emerging field because plant extracts are the best substitute for toxic chemicals. They are considered eco-friendly and cost-effective. In this work, two plant extracts, orange juice (ORJ) and lemon juice (LMJ), are used to synthesize the Sr0.8Ce0.2Fe0.8Co0.2O3 perovskite using the auto-combustion method. The electrochemical performance of Sr0.8Ce0.2Fe0.8Co0.2O3 made from LMJ and ORJ is compared to check their effectiveness. LMJ proved to be a better reducing agent than ORJ with a higher specific capacity of 300 C/g (544 F/g) at 1 A/g current density due to increased oxygen vacancies and surface area. These findings show that green-synthesized perovskites can be utilized in high-performance hybrid supercapacitor devices.

Graphical Abstract

1. Introduction

For a clean, energy-efficient system, shifting to renewable natural resources is necessary. These include solar energy, wind energy, etc., but the drawback of utilizing these resources is their discontinuous supply [1,2]. To resolve this issue, the scientific community is striving hard to manufacture energy storage devices with high capacity, cyclic life, energy and power density [3,4,5,6]. Supercapacitors are emerging energy storage devices that can provide all the above-mentioned advantages. They mainly consist of electrical double-layer capacitors (EDLCs) and pseudocapacitors. The working principle of EDLCs involves adsorption and desorption of ions which results in high cyclic stability [7,8,9,10]. On the other hand, pseudocapacitors work through redox reactions and result in high specific capacitance values. The combination of the two types results in asymmetric hybrid supercapacitor devices that have high specific capacitance as well as good cyclic stability [11,12].
Pseudocapacitors are mainly tested as positive electrodes and are further categorized into three types. The first type is redox potential, which stores charge through metal electrode polarization that occurs below the redox potential of the electrode material. The second is redox pseudocapacitance, which undergoes surface redox reactions. In surface redox reactions, the electrolyte ions accumulate near the electrode surface, and the exchange of electrolyte ions and electrons occurs, which is responsible for charge storage. Examples are metal oxides and conducting polymers. The third type is intercalation pseudocapacitors in which the ions intercalate into the electrode material. The phenomenon of intercalation and de-intercalation makes them high-energy storage devices [13]. The materials that fall under the category of intercalation pseudocapacitors are some metal-oxides, conducting polymers and new emerging perovskite oxides [14,15,16,17]. Perovskites are intercalation pseudocapacitive materials that are gaining popularity due to low cost, high-energy density and high oxygen vacancies [18].
The general formula for perovskite oxides is ABO3, where A denotes alkali or rare earth metals (La, Sr, Ce) and B denotes transition metals (Co, Fe, Mn). A site element takes up the centre of eight octahedra and is responsible for thermodynamic stability. In contrast, the B site element forms an octahedral with six oxygen atoms and undergoes electrochemical reactions [19,20,21,22]. They are rich in oxygen vacancies, which are responsible for their metallic character. The high electrical conductivity arises from the crossover of the Fermi level between the 3d orbital of the B-site element and the 2p orbital of oxygen in terms of the density of states. They work on the mechanism of oxygen ion O2− intercalation. The advantage of O2− intercalation over Li+ and Na+ is that it can accommodate two charges, which means that double the number of charges can be stored in a single charge–discharge cycle compared to monovalent Li+ and Na+. Since they undergo oxygen intercalation, it is essential to synthesize perovskite material with high oxygen vacancies for improved electrochemical performance [23].
Among all the perovskites, strontium-based materials have received considerable attention due to their natural abundance, high conductivity and cost-effectiveness [24,25,26,27]. Various strontium-based perovskites have been reported in the literature, particularly strontium ferrites [28,29,30]. According to the literature, appropriate element doping in these perovskites can induce structure distortion that is responsible for creating oxygen vacancies. Cerium is considered a good choice for A-site doping as it increases defect sites and has multiple oxidation states, Ce+3 and Ce+4, required for enhanced oxygen diffusion [31,32]. Moreover, aliovalent doping at the A-site generates redox couple Bn+/B(n+1)+, which enhances electrochemical performance.
The synthesis technique is an important parameter because the morphology and crystal structure of the material depend on it. There are various synthesis parameters to synthesize perovskite, such as ball milling, co-precipitation, the auto-combustion method, etc. The ball milling method involves heating the material at a high temperature that renders it with sluggish surface area properties. Co-precipitation involves low temperature, which results in non-uniform and agglomerated particles. The auto-combustion method is desirable for synthesizing perovskite material as it results in a controlled structure, uniform particle distribution and porosity, due to the evolution of gases that occur during combustion reactions. The disadvantage of the auto-combustion method is using non-biocompatible fuel as a chelating/reducing agent. The literature has reported that fuel plays a significant role as the material’s morphology, porosity and surface area depend on it. To create a bio-compatible system, the reactants and by-products should be non-toxic, eco-friendly, cost-effective, and easy to handle [33]. Many studies have discussed the role of different chelating agents and concluded that they affect the morphology and crystallite size of the material [34,35]. Green synthesis can provide an alternative to toxic chemicals by using biocompatible reducing agents.
Herein, we have used bio-compatible green reducing agents, i.e., ORJ and LMJ, to synthesize the perovskite material Sr0.8Ce0.2Fe0.8Co0.2O3 using the green auto-combustion method. Strontium-based perovskite is utilized because it is extensively studied in the literature and would make it easier to compare the results of bio-compatible chelating agents with non-biocompatible chelating agents. Furthermore, the cerium is used as an A-site substitution to stabilize the perovskite structure, and cobalt at the B-site is used because of its intrinsically high electronic and ionic conductivity. Two different fuels are used to study how the evolution of gases affects the reaction kinetics and results in different morphologies and crystallite sizes. The aim is to determine the effect of using a biocompatible reducing agent on the electrochemical performance of both electrodes. To the best of our knowledge, there is no previous work on synthesizing perovskite using plant extract and using it for supercapacitor application. This work will pave the way for using biocompatible reducing agents to synthesize perovskite material and exploit it in supercapacitor applications.

2. Materials and Methods

2.1. Powder Synthesis

All the materials were purchased from Sigma Aldrich and were used without further purification. Double-distilled water was obtained from the Milli-Q system. For the green auto-combustion synthesis method, lemon and orange juices were used as reducing agents. They were procured from the local market. To extract the lemons and oranges, they were first washed with DI water to remove any impurities. Then, with the help of a squeezer, their juice was extracted. The juice was filtered through Whatman filter paper various times to remove any residuals. The synthesis started by mixing the stoichiometric amount of strontium nitrate (Sr(NO3)2), cerium nitrate hexahydrate (Ce(NO3)3·6H2O), iron nitrate nanohydrate (Fe(NO3)3·9H2O) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O) in 20 mL of double-distilled water, individually. After that, the individual solutions were added to one large beaker. The stirring and heating were performed until a homogeneous solution was obtained. Then, 20 mL of lemon juice/orange juice was added dropwise as a fuel/reducing agent and left on the hot plate at 80 °C until the solution turned into a gel. The gel was then converted into ash after auto-combustion occurred. The ash was ground into powder, calcinated at 600 °C for 4 h, and then sintered at 1100 °C for 2 h. The whole synthesis process is schematically depicted in Figure 1.

2.2. Electrode Fabrication

After powder synthesis, electrodes were fabricated using the slurry method. Nickel (Ni) foam was used as the current collector and washed with 3 M HCL, ethanol, and DI water. The synthesized perovskite, carbon black and PVDF were dissolved in DMF solvent in a ratio of 80:10:10. The slurry was subjected to magnetic stirring until homogenously dispersed and then coated on pre-washed Ni foam (1 cm2 area). After coating, the electrodes were dried in an oven at 80 °C. The mass of the slurry on the electrodes was ~6 mg/cm2. The electrode in which the active material is synthesized from an orange juice-reducing agent is termed ORJ, and the other one as LMJ.

2.3. Powder Characterization

The powder was characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence (Pl). XRD pattern was obtained from diffractogram (Equinox 2000, Thermo Scientific, Waltham, MA, USA) for the 20°–80° theta range. SEM (Inspect S50, Thermo Scientific, Waltham, MA, USA) and EDAX (EDAX, Mahwa, NJ, USA) were used to study the material’s morphology and elements’ quantitative analysis. FTIR (Thermo Scientific Nicolet IS5 Instrument, Waltham, MA, USA) was performed for functional group analysis. For photoluminescence (FS5, Edinburgh Instruments, Livingston, UK) spectra, spectrofluorometer was used.

2.4. Electrochemical Characterization

The electrochemical performance of the electrodes LMJ and ORJ was first carried out in a three-electrode assembly. In a three-electrode assembly, LMJ and ORJ were used as working electrodes, Hg/HgO as the reference electrode and a graphite rod as the counter electrode. The device of the best electrode was then fabricated with LMJ as the positive electrode and activated carbon (AC) as the negative electrode. The filter paper was sandwiched between the two electrodes that acted as a separator, saving the device from a short-circuit. Throughout the experiment, 1 M aqueous electrolyte (KOH) was used. All the electrochemical characterization is carried out using Potentiostat 3000 (Gamry, Warminster, PA, USA). The charge was balanced for the device using the following equations [36,37]:
m L M J m A C = C s A C × V P A C C s L M J × V P L M J
where m denotes the mass, Cs denotes the specific capacity obtained in a three-electrode assembly and V denotes the potential window of the respective electrodes.
The specific capacity values obtained from CV and GCD, respectively, using the following formula [38]:
C s = I v d t v × m
where I v d t is the area under the positive curve, v scan rate.
C s = 2 × I V d t m × V
where V d t is the area under the discharge curve and V is the potential window.
Energy density and power density are calculated by using the following formula:
E n e r g y   D e n s i t y ( E d ) = C s × V 2 2 × 3.6
P o w e r   D e n s i t y ( P d ) = 3600 × E d t
where t is discharge time [39,40].

3. Results and Discussion

3.1. Crystal Structure

The crystal structure and phase of the as-synthesized perovskite Sr0.8Ce0.2Fe0.8Co0.2O3 are analyzed by XRD pattern. The XRD pattern with the indexed peaks shown in Figure 2a matches the previously reported literature [28,41,42]. The perovskite has a cubic structure with space group Pm-3m. The cerium is said to stabilize the overall perovskite structure at about 15 mol% [43,44,45]. However, one peak of Fe2O3 was also detected for both the reducing agents, which is matched with the COD database entry number (96-153-2122). This segregation could be due to the addition of cerium above 15 mol% to stabilize the cubic structure. No cobalt phase segregation is seen, which means cobalt is substituted easily at the B-site. The Rietveld refinement was carried out to extract the important structural information. It is given in Figure 2d,e for ORJ and LMJ. The LMJ refinement is done for both the phases of perovskite and Fe2O3. For ORJ, the Fe2O3 peak is small and close to the noise data, due to which it was difficult to refine. The R-factors and chi (χ) value, are given in Table 1. Firstly, the tolerance factor is calculated to prove the cubic structure of the prepared perovskite. For this, the radius values are obtained from the refinement which are 2.15 Å, 1.82 Å, 1.26 Å, 1.25 Å and 0.74 Å for Sr, Ce, Fe, Co and O, respectively. The formula for tolerance factor is given below:
t = r A + r O r B + r O
where rA, rB and rC are the radii of A-site, B-site cation and O anion, respectively [46]. The calculated tolerance factor for both ORJ and LMJ is calculated as 0.998, denoting a nearly cubic structure which is in accordance with our hypothesis and the literature. In order to maintain the cubic structure and charge neutrality of perovskite, the iron changes its oxidation state as follows [47]:
2 F e 4 + + O O X 2 F e 3 + + V Ö + 1 2 O 2 .
The greater ionic radii of Fe3+ led to the creation of oxygen vacancies desirable for improved electrochemical performance. The bond valence (BV) calculation is performed to obtain the oxidation state of both strontium and iron from the bond angle values using the following formula:
B V = exp R o R B
where Ro is the empirically derived bond valence, R is observed, and b is 0.37 as a universal constant.
B V S = B V C N
where CN is the coordination number [48]. The bond valence sum (BVS) value gives the oxidation state of the element. The calculated values for both the LMJ and ORJ are given in Table 1.
It can be seen that both LMJ and ORJ have Sr oxidation states close to +2, which means that strontium did not undergo oxidation state change. For Fe, ORJ has oxidation state +3.56 and LMJ +3.70, indicating the presence of Fe3+ and hence increased oxygen vacancies in both the materials. The crystallite size of the perovskite prepared from different fuels is calculated from the Scherrer formula:
C r y s t a l l i t e   s i z e D = k λ β c o s θ
where k is referred to as the shape factor, λ is the X-ray wavelength, β is the full-width at half maxima and cosθ is the angle at which the individual peaks appear [49,50]. Perovskite prepared from LMJ as a reducing agent has a lower crystallite size (36 nm) than ORJ (53 nm), which means it should possess a high surface area. The change in crystallite size calculated from XRD confirms how the combustion reaction with different reducing agents affects the material parameters.

3.2. Chemical Bond Analysis

FTIR is used to analyze the chemical composition of the material. Perovskites have the formula ABO3, where A is located at the centre and B at the octahedral site surrounded by a coordination of six oxygen anions. The FTIR analysis for ORJ and LMJ was carried out for 400–4000 cm−1, as shown in Figure 2b. For perovskite, an intense peak appears around ~600 cm−1, resulting in M–O bond stretching, where M is a transition metal [51]. For ORJ and LMJ, peaks appear at this wavelength supporting the XRD results of the successful synthesis of the perovskite structure. It can be seen that small peaks appear at 1433 cm−1, 2352 cm−1, 2885 cm−1 and 2944 cm−1. These peaks are due to the symmetric and asymmetric stretching of C–H bonds. The peak around 1000 and 3400 cm−1 in LMJ is due to the -OH group arising from the adsorption of water molecules on the surface [52].

3.3. Photoluminescence

Photoluminescence (PL) is used to study the optical and electronic properties of the material with respect to the defect states. Figure 2c shows the PL spectra of the obtained perovskite materials LMJ and ORJ. The PL spectra have prominent peaks at 377, 431, 465 and 542 nm. The 377 nm peak appears due to near-band emission. The peak appearing at 377 nm is due to the recombination of electrons with structural defects [53]. ORJ has greater intensity for these defects, which means it has greater electron recombination, resulting in lower electrical conductivity. The oxygen vacancy-related defects appear around 550 nm [54]. It can be seen in the figure that LMJ has greater oxygen vacancies than ORJ, as it has the highest intensity, which corroborates with XRD analysis. These oxygen vacancies provide sites for oxygen intercalation. Both factors increase the overall electrochemical performance of the LMJ electrode.

3.4. Morphological Study

The morphology and elemental composition are studied by SEM and EDX, respectively. The morphology of both ORJ and LMJ consists of irregularly shaped particles with varying sizes, as shown in Figure 3a,b,d,e. The particle size of LMJ is smaller than ORJ, as seen in SEM images. The smaller particle size of LMJ compared to ORJ depicts its high surface area, which is corroborated by the crystallite size of XRD. Hence, it can exhibit good electrochemical properties as compared to ORJ. The point analysis for element detection through EDX spectra is shown in Figure 3c,f. The presence of all the elements in LMJ and ORJ confirms their successful synthesis.

3.5. Electrochemical Performance in Three-Electrode Assembly

The electrochemical potential of the electrodes ORJ and LMJ is first analyzed in a three-electrode assembly before being utilized as a hybrid supercapacitor device. The cyclic voltammetry (CV) curves are plotted with potential (V vs. Hg/HgO) on the x-axis and current density on the y-axis. Both electrodes showed oxidation and reduction peaks, which means both were undergoing diffusion-controlled processes, confirming intercalation pseudocapacitance. Figure 4a,b shows the CV curves of both the ORJ and LMJ electrodes at various scan rates. As the electrodes show a diffusive-controlled mechanism, specific capacity is calculated and plotted as a scan rate function in Figure 4c. It can be seen that the specific capacity value is maximum at lower scan rates and decreases as we go up to the higher scan rates. This trend is due to insufficient time available for the diffusion of ions as the scan rate increases. The highest specific capacity of 320 C/g is achieved for LMJ at a 1 mV/s scan rate, almost double that of ORJ, which is 160 C/g.
Galvanostatic charge–discharge (GCD) was carried out for further electrochemical analysis. The discharge curves of ORJ and LMJ are plotted with potential on the y-axis and discharge time on the x-axis, as shown in Figure 4d,e. The plateaus in the discharge curves of both electrodes confirm the occurrence of diffusion-controlled mechanisms. The curves are taken at different current densities, and the calculated specific capacities as a function of these densities are shown in Figure 4f. The results correlate with the CV as LMJ has a high specific capacity of 300 C/g at 1 A/g current density compared to ORJ, which is only 158 C/g. Figure 4g shows comparison curves of both electrodes at a 1 mV/s scan rate, clearly showing the oxidation and reduction peaks for both electrodes, with LMJ having a greater area under the curve. Similarly, Figure 4h shows the discharge curve comparison with LMJ, showing a greater area than ORJ.
Cyclic stability and coulombic efficiency for the best-performing sample LMJ were calculated for 2500 cycles as shown in Figure 5a. Cyclic stability showed a decline at the start due to volume changes happening in perovskite, but after a few cycles, it was stabilized to 72%. However, the coulombic efficiency was retained at 98%. Electrochemical Impedance Spectroscopy (EIS) gives valuable electrochemical information on the electrode kinetics. Two plots are obtained from EIS at a frequency range of 0.1 Hz to 100 kHz: the Nyquist plot and the Bode plot. A comparison of the Nyquist plot is shown in Figure 5b. The starting region where the semi-circle forms is the high-frequency region, and the tail region is the low-frequency region. The two important parameters, namely electrical series resistance (ESR) and charge transfer resistance (Rct), are obtained from this plot. ESR depicts the ionic conductivity of the electrode, and the lower value denotes the material’s good ionic conductivity. Rct is charge transfer resistance, and its low value denotes the excellent interaction of electrolyte ions with the electrode material. ESR values for ORJ and LMJ are calculated as 1.54 Ω and 1.52 Ω.
On the other hand, the Rct value for LMJ is negligible as no significant semi-circle region is seen, whereas 21.46 Ω was calculated for ORJ. The results showed that LMJ has good ionic conductivity and interaction with electrolyte ions. Figure 5c,d shows the Bode plot for LMJ and ORJ, respectively. It can be seen that LMJ has a lower impedance than ORJ, which is responsible for its good electrochemical performance. The phase angle close to 90° shows the capacitive behaviour of the electrode, whereas the deviation from 90° denotes the presence of redox reactions and a diffusive-controlled mechanism. Both electrodes show a deviation from 90°, further supporting their diffusive nature and the occurrence of redox reactions.
For the in-depth study of the mechanism, the b-value is calculated for both electrodes from the power law [55]. If the b-value is 0.5 ≥ b, the diffusive-controlled mechanism prevails, b ≥ 1, the capacitive-controlled mechanism prevails and value 1 > b ≥ 0.5 denotes the transition. Both electrodes have a b-value close to 0.5, as shown in Figure 6a. Hence, the diffusive-controlled mechanism prevails in both electrodes. To further dig into the charge contribution, the Trasatti method is used, which quantifies the inner charge contribution and outer charge distribution [56]. The intercepts of the plots in Figure 6c,e are used to calculate the inner charge contribution for ORJ and LMJ, respectively. Likewise, the intercepts of the plot in Figure 6d,f are used to calculate the inner charge contribution for ORJ and LMJ, respectively. The ORJ showed 4% outer and 96% inner charge storage, while the LMJ showed 6% outer and 93% inner charge storage. Figure 6g,h shows the R2 values for ORJ and LMJ, respectively. R2 values closer to 1 show good reversibility of reactions, and both electrodes have values closer to 1.
The capacitive and diffusive contribution at each scan rate is calculated by Dunn’s model, which is given as follows [57]:
i ( V ) = k 1 v + k 2 v 1 / 2 .
By rearranging the equation, it becomes:
i ( V ) v 1 / 2 = k 1 v + k 2
where k1 is slope and k2 is intercept. Figure 7a,b is plotted between potential and current density for ORJ and LMJ, respectively, at a 5 mV/s scan rate. The purpose of this is to identify the capacitive contribution from the CV data obtained experimentally. It can be clearly seen that LMJ has a more diffusive area. The capacitive and diffusive contribution at each scan rate is depicted in Figure 7c,d. At low scan rates, the diffusive mechanism is dominant, and at higher scan rates, the capacitive mechanism dominates. For the LMJ electrode, the diffusive mechanism dominates at each scan rate as compared to ORJ because of high oxygen ion intercalation. To confirm this, the diffusion coefficient is calculated using the following equation:
D = R 2 T 2 2 A 2 n 4 F 4 C 2 σ 2
In the above equation, D is the diffusion coefficient, R is the universal gas constant (8.314 J mol−1 k−1, T is temperature in kelvin, A is surface area in cm2, n is the number of electrons transfer, F is Faraday’s constant (96485 C mol−1), C is the molar concentration of ions in mol cm−3 and σ is the Warburg co-efficient. The Warburg coefficient is obtained from the slope of Z’ versus ω−1/2 [58]. The diffusion coefficient calculated from Equation (13) is 5.58 × 10−12 for LMJ and 7.59 × 10−14 for ORJ. Hence, the results correlate with the high diffusive contribution of LMJ as it has a high oxygen diffusion coefficient.
  • Working Mechanism
The LMJ and ORJ work on the oxygen anion-type intercalation charge storage mechanism. The structure obtained from Vesta software (Version 4.0.0) after refinement is shown in Figure 8. The addition of cerium led to the formation of oxygen vacancies as discussed above and provides an increased number of active sites for oxygen intercalation. On the other hand, cobalt has good ionic conductivity that facilitates enhanced diffusion of ions. First, the OH ion from the electrolyte reaches the electrode surface, where it undergoes the dissociation process as follows:
OH → O2− + H+.
This O2− ion will diffuse across the perovskite grain boundaries and reach the oxygen vacancies present. As a result of the intercalation of this oxygen anion, the transition metal oxides will change their oxidation states [28] according to Equation (15):
  • Oxygen Intercalation
    S r 0.8 C e 0.2 ( F e 3 + ) 0.8 C o 3 +   0.2 O 3 + α O H                                                                                                                                                           S r 0.8 C e 0.2 ( F e 4 + ) 0.8 C o 4 +   0.2 O 3 x + α e + α H 2 O
  • Surface Redox Pseudocapacitance
    F e 2 O 3 + 2 e + 3 H 2 O 2 F e ( O H ) 2 + 2 O H
    F e O O H + H 2 O + e F e ( O H ) 2 + O H
Due to the presence of segregated Fe2O3, it contributed to surface pseudocapacitance as shown in Equations (16) and (17) [59]. The electrochemical performance in the three-electrode assembly concluded that the LMJ was a better-performing electrode than ORJ because of the advantage of small particle size, which endowed it with good electrical conductivity. Secondly, the greater phase segregation of the secondary phase in LMJ contributed to enhanced surface pseudocapacitance along with oxygen intercalation.
The results are also comparable with the reported literature for similar perovskite materials in Table 2.

3.6. Electrochemical Performance in Two-Electrode Assembly

The best-performing electrode, LMJ, was utilized in a hybrid supercapacitor device (LMJ||AC) with LMJ as the positive electrode and commercially available activated carbon (AC) as the negative electrode. The potential window of 1.6 V is selected based on the potential window of individual electrodes, as shown in Figure 9a. The device is operated at different scan rates to see the electrochemical behaviour, as shown in Figure 9b. It can be seen that the CV curves are quasi-rectangular with redox peaks that confirm both the capacitive (due to the activated carbon electrode) and diffusive (LMJ electrode) charge storage mechanisms occurring in the device. The curves maintain shape at low and high scan rates, showing electrochemical reversibility. Figure 9c shows the galvanostatic charge–discharge curves of the device at different current densities. The curves maintain triangular symmetry with slight plateaus, confirming the occurrence of both mechanisms. The specific capacity values are calculated and given as a function of current density in Figure 9d. The highest capacity achieved for the LMJ||AC device is 364 C/g at 1 A/g current density, received due to the synergistic effect of both electrodes. Cyclic stability is essential to determine the practical application of the device. The excellent device showed 98% cyclic stability over 5000 GCD cycles. It not only demonstrated high cyclic stability of 98%, but also showed good coulombic efficiency of 99%, as shown in Figure 9e. The Nyquist plot before and after the cyclic stability test is shown in Figure 9f. The ESR value increased slightly from 2.2 to 2.4 Ω after 5000 GCD cycles. The Rct value before the cyclic test was negligible, and after, it was 5 ohms, which could be due to the continuous intercalation and de-intercalation of ions.
The b-value is calculated to depict the charge storage mechanism, as seen in Figure 10a. For the device, the b-value closer to 0.5 depicts diffusive-controlled behaviour, the one closer to 1 represents the capacitive mechanism, and the values in between show the presence of both. The b-value calculated for the device is 0.75, showing that the device is a hybrid supercapacitor working on both mechanisms. The capacitive and diffusive contribution for the LMJ||AC device at each scan rate is calculated by Dunn’s model using Equation (12).
The diffusive-controlled mechanism dominates at lower scan rates, and the capacitive mechanism dominates at higher scan rates, as shown in Figure 10b. Energy and power density are crucial for the practical utilization of the device. Figure 10c shows the comparison of energy and power density of this work with the reported literature as a Ragone plot [29,63,64,65,66,67]. The highest energy density achieved is 80 Wh/kg at a power density of 3609 W/kg at 1 A/g current density, making it a well-performing device.
Figure 10. (a) The b-value calculation for the LMJ||AC device. (b) Capacitive and diffusive contribution percentages obtained at different scan rates. (c) Ragone plot of the device showing power density on the x-axis and energy density on the y-axis [29,63,64,65,66,67].
Figure 10. (a) The b-value calculation for the LMJ||AC device. (b) Capacitive and diffusive contribution percentages obtained at different scan rates. (c) Ragone plot of the device showing power density on the x-axis and energy density on the y-axis [29,63,64,65,66,67].
Batteries 11 00310 g010

4. Conclusions

In conclusion, the facile and simple auto-combustion method was used to synthesize the Sr0.8Ce0.2Fe0.8Co0.2O3 perovskite with two different bio-compatible reducing agents. The XRD confirmed the successful synthesis of perovskite with a cubic crystal structure for both reducing agents. The transition of Fe4+ to Fe3+ introduces oxygen vacancies, which is further confirmed by Rietveld refinement of XRD data and PL spectra. The abundant oxygen vacancies, larger surface area and secondary phase proved to be favourable for the electrochemical performance of LMJ. The fabricated LMJ||AC device showed a remarkable 98% cyclic stability even after 5000 GCD cycles. This study explores the effective utilization of bio-compatible reducing agents for synthesizing perovskites and utilizing them for supercapacitor device fabrication.

Author Contributions

A.F.: Conceptualization, Data Curation, Investigation, Methodology, Visualization, Writing—original draft. M.J.I.: Supervision, Conceptualization, Validation, Funding, Writing—review and editing. M.A.R.: Supervision, Validation, Writing—review and editing. B.S.A.: Formal Analysis, Funding, Writing—review and editing. H.M.H.Z.: Formal Analysis, Validation, Visualization. N.A., Formal Analysis, Visualization, Validation. M.I.: Methodology, Visualization, Formal Analysis. S.R.: Validation, Visualization. All authors have read and agreed to the published version of the manuscript.

Funding

This research work was partially supported by the University of the Punjab, Lahore, Pakistan, through a research project grant for the fiscal year 2024–2025. In addition, this research was supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project Number (PNURSP2025R327), Princess Nourah bint Abdulrehman University, Riyadh, Saudi Arabia.

Data Availability Statement

Data will be provided on demand.

Acknowledgments

The authors acknowledges the funding by Princess Nourah bint Abdulrehman University Researchers Supporting Project Number (PNURSP2025R327), Princess Nourah bint Abdulrehman University, Riyadh, Saudi Arabia.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Dhaouadi, R.; Al-Othman, A.; Aidan, A.A.; Tawalbeh, M.; Zannerni, R. A Characterization Study for the Properties of Dust Particles Collected on Photovoltaic (PV) Panels in Sharjah, United Arab Emirates. Renew. Energy 2021, 171, 133–140. [Google Scholar] [CrossRef]
  2. Mahmoud, M.; Ramadan, M.; Olabi, A.-G.; Pullen, K.; Naher, S. A Review of Mechanical Energy Storage Systems Combined with Wind and Solar Applications. Energy Convers. Manag. 2020, 210, 112670. [Google Scholar] [CrossRef]
  3. Jiang, H.; Ma, H.; Jin, Y.; Wang, L.; Gao, F.; Lu, Q. Hybrid α-Fe2O3@ Ni(OH)2 Nanosheet Composite for High-Rate-Performance Supercapacitor Electrode. Sci. Rep. 2016, 6, 31751. [Google Scholar] [CrossRef] [PubMed]
  4. Samantaray, S.; Mohanty, D.; Hung, I.-M.; Moniruzzaman, M.; Satpathy, S.K. Unleashing Recent Electrolyte Materials for Next-Generation Supercapacitor Applications: A Comprehensive Review. J. Energy Storage 2023, 72, 108352. [Google Scholar] [CrossRef]
  5. Du, N.; Zheng, W.; Li, X.; He, G.; Wang, L.; Shi, J. Nanosheet-Assembled NiS Hollow Structures with Double Shells and Controlled Shapes for High-Performance Supercapacitors. Chem. Eng. J. 2017, 323, 415–424. [Google Scholar] [CrossRef]
  6. Zhou, Y.; Maleski, K.; Anasori, B.; Thostenson, J.O.; Pang, Y.; Feng, Y.; Zeng, K.; Parker, C.B.; Zauscher, S.; Gogotsi, Y.; et al. Ti3C2Tx MXene-Reduced Graphene Oxide Composite Electrodes for Stretchable Supercapacitors. ACS Nano 2020, 14, 3576–3586. [Google Scholar] [CrossRef]
  7. Tatrari, G.; Karakoti, M.; Tewari, C.; Pandey, S.; Bohra, B.S.; Dandapat, A.; Sahoo, N.G. Solid Waste-Derived Carbon Nanomaterials for Supercapacitor Applications: A Recent Overview. Mater. Adv. 2021, 2, 1454–1484. [Google Scholar] [CrossRef]
  8. Maity, C.K.; Goswami, N.; Verma, K.; Sahoo, S.; Nayak, G.C. A Facile Synthesis of Boron Nitride Supported Zinc Cobalt Sulfide Nano Hybrid as High-Performance Pseudocapacitive Electrode Material for Asymmetric Supercapacitors. J. Energy Storage 2020, 32, 101993. [Google Scholar] [CrossRef]
  9. Oje, A.I.; Ogwu, A.A.; Mirzaeian, M.; Tsendzughul, N.; Oje, A.M. Pseudo-Capacitance of Silver Oxide Thin Film Electrodes in Ionic Liquid for Electrochemical Energy Applications. J. Sci. Adv. Mater. Devices 2019, 4, 213–222. [Google Scholar] [CrossRef]
  10. Li, X.; Wei, B. Supercapacitors Based on Nanostructured Carbon. Nano Energy 2013, 2, 159–173. [Google Scholar] [CrossRef]
  11. Abbas, Q.; Raza, R.; Shabbir, I.; Olabi, A.G. Heteroatom Doped High Porosity Carbon Nanomaterials as Electrodes for Energy Storage in Electrochemical Capacitors: A Review. J. Sci. Adv. Mater. Devices 2019, 4, 341–352. [Google Scholar] [CrossRef]
  12. Ponce, M.F.; Mamani, A.; Jerez, F.; Castilla, J.; Ramos, P.B.; Acosta, G.G.; Sardella, M.F.; Bavio, M.A. Activated Carbon from Olive Tree Pruning Residue for Symmetric Solid-State Supercapacitor. Energy 2022, 260, 125092. [Google Scholar] [CrossRef]
  13. Augustyn, V.; Simon, P.; Dunn, B. Pseudocapacitive Oxide Materials for High-Rate Electrochemical Energy Storage. Energy Environ. Sci. 2014, 7, 1597–1614. [Google Scholar] [CrossRef]
  14. Sahoo, R.; Pal, A.; Pal, T. Noble Metal–Transition Metal Oxides/Hydroxides: Desired Materials for Pseudocapacitor. In Noble Metal-Metal Oxide Hybrid Nanoparticles; Elsevier: Amsterdam, The Netherlands, 2019; pp. 395–430. [Google Scholar]
  15. Brezesinski, K.; Wang, J.; Haetge, J.; Reitz, C.; Steinmueller, S.O.; Tolbert, S.H.; Smarsly, B.M.; Dunn, B.; Brezesinski, T. Pseudocapacitive Contributions to Charge Storage in Highly Ordered Mesoporous Group V Transition Metal Oxides with Iso-Oriented Layered Nanocrystalline Domains. J. Am. Chem. Soc. 2010, 132, 6982–6990. [Google Scholar] [CrossRef] [PubMed]
  16. Umar, A.; Ahmed, F.; Ullah, N.; Ansari, S.A.; Hussain, S.; Ibrahim, A.A.; Qasem, H.; Kumar, S.A.; Alhamami, M.A.; Almehbad, N. Exploring the Potential of Reduced Graphene Oxide/Polyaniline (rGO@ PANI) Nanocomposites for High-Performance Supercapacitor Application. Electrochim. Acta 2024, 479, 143743. [Google Scholar] [CrossRef]
  17. Liu, Y.; Wang, Z.; Zhong, Y.; Xu, X.; Veder, J.-P.M.; Rowles, M.R.; Saunders, M.; Ran, R.; Shao, Z. Activation-Free Supercapacitor Electrode Based on Surface-Modified Sr2CoMo1-xNixO6-δ Perovskite. Chem. Eng. J. 2020, 390, 124645. [Google Scholar] [CrossRef]
  18. Cao, Y.; Liang, J.; Li, X.; Yue, L.; Liu, Q.; Lu, S.; Asiri, A.M.; Hu, J.; Luo, Y.; Sun, X. Recent Advances in Perovskite Oxides as Electrode Materials for Supercapacitors. Chem. Commun. 2021, 57, 2343–2355. [Google Scholar] [CrossRef]
  19. Nguyen, T.; Montemor, M.D.F. Metal Oxide and Hydroxide–Based Aqueous Supercapacitors: From Charge Storage Mechanisms and Functional Electrode Engineering to Need-Tailored Devices. Adv. Sci. 2019, 6, 1801797. [Google Scholar] [CrossRef]
  20. 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. [Google Scholar] [CrossRef]
  21. Ji, Q.; Bi, L.; Zhang, J.; Cao, H.; Zhao, X.S. The Role of Oxygen Vacancies of ABO 3 Perovskite Oxides in the Oxygen Reduction Reaction. Energy Environ. Sci. 2020, 13, 1408–1428. [Google Scholar] [CrossRef]
  22. Agarwal, A.; Sankapal, B.R. Metal Phosphides: Topical Advances in the Design of Supercapacitors. J. Mater. Chem. A 2021, 9, 20241–20276. [Google Scholar] [CrossRef]
  23. Liu, Y.; Jiang, S.P.; Shao, Z. Intercalation Pseudocapacitance in Electrochemical Energy Storage: Recent Advances in Fundamental Understanding and Materials Development. Mater. Today Adv. 2020, 7, 100072. [Google Scholar] [CrossRef]
  24. Wu, M.-C.; Chen, W.-C.; Chan, S.-H.; Su, W.-F. The Effect of Strontium and Barium Doping on Perovskite-Structured Energy Materials for Photovoltaic Applications. Appl. Surf. Sci. 2018, 429, 9–15. [Google Scholar] [CrossRef]
  25. Adimule, V.; Bhat, V.S.; Yallur, B.C.; Gowda, A.H.; Padova, P.D.; Hegde, G.; Toghan, A. Facile Synthesis of Novel SrO0.5: MnO0.5 Bimetallic Oxide Nanostructure as a High-Performance Electrode Material for Supercapacitors. Nanomater. Nanotechnol. 2022, 12, 184798042110640. [Google Scholar] [CrossRef]
  26. Liu, G.F.; Ma, P.P.; Qiao, Y.; Xu, R.H.; Hu, R.Y.; Liu, L.Y.; Jiang, G.H.; Demir, M. Perovskite SrCo1-xTixO3-δ as Anion-Intercalated Electrode Materials for Supercapacitors. J. Energy Storage 2022, 52, 104942. [Google Scholar] [CrossRef]
  27. Salas, M.A.S.; De Paoli, J.M.; Pérez, O.E.L.; Bajales, N.; Fuertes, V.C. Synthesis and Characterization of Alumina-Embedded SrCo0.95V0.05O3 Nanostructured Perovskite: An Attractive Material for Supercapacitor Devices. Microporous Mesoporous Mater. 2020, 293, 109797. [Google Scholar] [CrossRef]
  28. Ahangari, M.; Mostafaei, J.; Sayyah, A.; Mahmoudi, E.; Asghari, E.; Coruh, A.; Delibas, N.; Niaei, A. Investigation of Structural and Electrochemical Properties of SrFexCo1-xO3-δ Perovskite Oxides as a Supercapacitor Electrode Material. J. Energy Storage 2023, 63, 107034. [Google Scholar] [CrossRef]
  29. Qiao, Y.; Liu, G.; Xu, R.; Hu, R.; Liu, L.; Jiang, G.; Demir, M.; Ma, P. SrFe1-xZrxO3-δ Perovskite Oxides as Negative Electrodes for Supercapacitors. Electrochim. Acta 2023, 437, 141527. [Google Scholar] [CrossRef]
  30. Mendoza, R.; Oliva, J.; Padmasree, K.P.; Mtz-Enriquez, A.I.; Zakhidov, A.; Encinas, A. Using the Amorphous-Carbon Derived from Cigarette Filters for the Fabrication of Highly Efficient Flexible Supercapacitors and Role of the Sr3.2Y0.8Fe1.5Co1.5O10 Layered Perovskite to Enhance Their Electrochemical Performance. J. Energy Storage 2023, 60, 106539. [Google Scholar] [CrossRef]
  31. Maheswari, N.; Muralidharan, G. Supercapacitor Behavior of Cerium Oxide Nanoparticles in Neutral Aqueous Electrolytes. Energy Fuels 2015, 29, 8246–8253. [Google Scholar] [CrossRef]
  32. Ansari, A.A.; Adil, S.F.; Alam, M.; Ahmad, N.; Assal, M.E.; Labis, J.P.; Alwarthan, A. Catalytic Performance of the Ce-Doped LaCoO3 Perovskite Nanoparticles. Sci. Rep. 2020, 10, 15012. [Google Scholar] [CrossRef]
  33. Mohan, M.; Shetti, N.P.; Aminabhavi, T.M. Perovskites: A New Generation Electrode Materials for Storage Applications. J. Power Sources 2023, 574, 233166. [Google Scholar] [CrossRef]
  34. Liu, Z.; Li, L.; Chen, J.; Yang, H.; Xia, L.; Chen, J.; Duan, J.; Chen, Z. Effects of Chelating Agents on Electrochemical Properties of Na0.9Ni0.45Mn0.55O2 Cathode Materials. J. Alloys Compd. 2021, 855, 157485. [Google Scholar] [CrossRef]
  35. Priyadharsini, N.; Kasturi, P.R.; Shanmugavani, A.; Surendran, S.; Shanmugapriya, S.; Selvan, R.K. Effect of Chelating Agent on the Sol-Gel Thermolysis Synthesis of LiNiPO4 and Its Electrochemical Properties for Hybrid Capacitors. J. Phys. Chem. Solids 2018, 119, 183–192. [Google Scholar] [CrossRef]
  36. Kumar, Y.A.; Kumar, K.D.; Kim, H.-J. Facile Preparation of a Highly Efficient NiZn2O4-NiO Nanoflower Composite Grown on Ni Foam as an Advanced Battery-Type Electrode Material for High-Performance Electrochemical Supercapacitors. Dalton Trans. 2020, 49, 3622–3629. [Google Scholar] [CrossRef] [PubMed]
  37. Kumar, R.D.; Kumar, A.J.; Balachandran, S.; Kusmartsev, F.V.; Trabelsi, A.B.G.; Alkallas, F.H.; Nagarani, S.; Sethuraman, V.; Lee, B.-K. High-Performance Chrysanthemum Flower-like Structure of Ni Doped ZnO Nanoflowers for Pseudo-Supercapacitors. J. Energy Storage 2023, 72, 108441. [Google Scholar] [CrossRef]
  38. Fazal, A.; Iqbal, M.J.; Raza, M.A.; Almutairi, B.S.; Iqbal, M.Z.; Subhani, T.; Riaz, S.; Naseem, S. Binder-Free Hydrothermal Approach to Fabricate High-Performance Zinc Phosphate Electrode for Energy Storage Applications. Ceram. Int. 2024, 50, 2742–2753. [Google Scholar] [CrossRef]
  39. Hekmat, F.; Hosseini, H.; Shahrokhian, S.; Unalan, H.E. Hybrid Energy Storage Device from Binder-Free Zinc-Cobalt Sulfide Decorated Biomass-Derived Carbon Microspheres and Pyrolyzed Polyaniline Nanotube-Iron Oxide. Energy Storage Mater. 2020, 25, 621–635. [Google Scholar] [CrossRef]
  40. Zhao, F.; Xie, D.; Song, X.; Wu, H.; Zhang, Q.; Zou, J.; Zeng, X. Construction of Hydrangea-like Nickel Cobalt Sulfide through Efficient Microwave-Assisted Approach for Remarkable Supercapacitors. Appl. Surf. Sci. 2021, 539, 148260. [Google Scholar] [CrossRef]
  41. Tummino, M.L.; Liotta, L.F.; Magnacca, G.; Lo Faro, M.; Trocino, S.; Campagna Zignani, S.; Aricò, A.S.; Deganello, F. Sucrose-Assisted Solution Combustion Synthesis of Doped Strontium Ferrate Perovskite-Type Electrocatalysts: Primary Role of the Secondary Fuel. Catalysts 2020, 10, 134. [Google Scholar] [CrossRef]
  42. Tummino, M.L.; Vineis, C.; Varesano, A.; Liotta, L.F.; Rigoletto, M.; Laurenti, E.; Deganello, F. Sr0.85Ce0.15Fe0.67Co0.33-xCuxO3 Perovskite Oxides: Effect of B-Site Copper Codoping on the Physicochemical, Catalytic and Antibacterial Properties upon UV or Thermal Activation. Front. Environ. Eng. 2023, 2, 1249931. [Google Scholar] [CrossRef]
  43. Deganello, F.; Liotta, L.F.; Leonardi, S.G.; Neri, G. Electrochemical Properties of Ce-Doped SrFeO3 Perovskites-Modified Electrodes towards Hydrogen Peroxide Oxidation. Electrochim. Acta 2016, 190, 939–947. [Google Scholar] [CrossRef]
  44. Tummino, M.L.; Laurenti, E.; Deganello, F.; Prevot, A.B.; Magnacca, G. Revisiting the Catalytic Activity of a Doped SrFeO3 for Water Pollutants Removal: Effect of Light and Temperature. Appl. Catal. B Environ. 2017, 207, 174–181. [Google Scholar] [CrossRef]
  45. Markov, A.A.; Nikitin, S.S.; Leonidov, I.A.; Patrakeev, M.V. Oxygen and Electron Transport in Ce0.1Sr0.9FeO3-δ. Solid. State Ion. 2020, 344, 115131. [Google Scholar] [CrossRef]
  46. Wei, Y.; Gui, H.; Zhao, Z.; Li, J.; Liu, Y.; Xin, S.; Li, X.; Xie, W. Structure and Magnetic Properties of the Perovskite YCo0.5Fe0.5O3. AIP Adv. 2014, 4, 127134. [Google Scholar] [CrossRef]
  47. Yao, C.; Zhang, H.; Liu, X.; Meng, J.; Meng, J.; Meng, F. A Niobium and Tungsten Co-Doped SrFeO3-δ Perovskite as Cathode for Intermediate Temperature Solid Oxide Fuel Cells. Ceram. Int. 2019, 45, 7351–7358. [Google Scholar] [CrossRef]
  48. Palenik, R.C.; Abboud, K.A.; Palenik, G.J. Bond Valence Sums and Structural Studies of Antimony Complexes Containing Sb Bonded Only to O Ligands. Inorganica Chim. Acta 2005, 358, 1034–1040. [Google Scholar] [CrossRef]
  49. Talaei, M.; Hassanzadeh-Tabrizi, S.A.; Saffar-Teluri, A. Synthesis of Mesoporous CuFe2O4@ SiO2 Core-Shell Nanocomposite for Simultaneous Drug Release and Hyperthermia Applications. Ceram. Int. 2021, 47, 30287–30297. [Google Scholar] [CrossRef]
  50. Aydoghmish, S.M.; Hassanzadeh-Tabrizi, S.A.; Saffar-Teluri, A. Facile Synthesis and Investigation of NiO-ZnO-Ag Nanocomposites as Efficient Photocatalysts for Degradation of Methylene Blue Dye. Ceram. Int. 2019, 45, 14934–14942. [Google Scholar] [CrossRef]
  51. Pecchi, G.; Campos, C.; Peña, O. Thermal Stability against Reduction of LaMn1−yCoyO3 Perovskites. Mater. Res. Bull. 2009, 44, 846–853. [Google Scholar] [CrossRef]
  52. Zheng, X.; Li, B.; Shen, L.; Cao, Y.; Zhan, Y.; Zheng, S.; Wang, S.; Jiang, L. Oxygen Vacancies Engineering of Fe Doped LaCoO3 Perovskite Catalysts for Efficient H2S Selective Oxidation. Appl. Catal. B Environ. 2023, 329, 122526. [Google Scholar] [CrossRef]
  53. Asaithambi, S.; Sakthivel, P.; Karuppaiah, M.; Yuvakkumar, R.; Balamurugan, K.; Ahamad, T.; Khan, M.M.; Ramalingam, G.; Mohammed, M.K.; Ravi, G. Preparation of Fe-SnO2@ CeO2 Nanocomposite Electrode for Asymmetric Supercapacitor Device Performance Analysis. J. Energy Storage 2021, 36, 102402. [Google Scholar] [CrossRef]
  54. Manju; Jain, M.; Madas, S.; Vashishtha, P.; Rajput, P.; Gupta, G.; Kahaly, M.U.; Özdoğan, K.; Vij, A.; Thakur, A. Oxygen Vacancies Induced Photoluminescence in SrZnO2 Nanophosphors Probed by Theoretical and Experimental Analysis. Sci. Rep. 2020, 10, 17364. [Google Scholar]
  55. Suggana, P.; Kumar, E.P.; Reddy, K.C.; Lakshmaiah, M.V.; Joo, S.W.; Reddy, G.R. 2D Sheet to 1D Rod-like Morphology Regulated Self-Assembled ZnCo2O4 Microstructures under Mixed Solvent Conditions for Battery-Type Supercapacitors. Colloids Surf. A Physicochem. Eng. Asp. 2023, 669, 131423. [Google Scholar] [CrossRef]
  56. Seenivasan, S.; Shim, K.I.; Lim, C.; Kavinkumar, T.; Sivagurunathan, A.T.; Han, J.W.; Kim, D.-H. Boosting Pseudocapacitive Behavior of Supercapattery Electrodes by Incorporating a Schottky Junction for Ultrahigh Energy Density. Nano-Micro Lett. 2023, 15, 62. [Google Scholar] [CrossRef]
  57. Liang, M.; Zhao, M.; Wang, H.; Shen, J.; Song, X. Enhanced Cycling Stability of Hierarchical NiCo2S4@ Ni(OH)2@ PPy Core–Shell Nanotube Arrays for Aqueous Asymmetric Supercapacitors. J. Mater. Chem. A 2018, 6, 2482–2493. [Google Scholar] [CrossRef]
  58. William, J.J.; Balakrishnan, S.; Murugesan, M.; Gopalan, M.; Britten, A.J.; Mkandawire, M. Mesoporous β-Ag2MoO4 Nanopotatoes as Supercapacitor Electrodes. Mater. Adv. 2022, 3, 8288–8297. [Google Scholar] [CrossRef]
  59. Safari, M.; Mazloom, J.; Boustani, K.; Monemdjou, A. Hierarchical Fe2O3 Hexagonal Nanoplatelets Anchored on SnO2 Nanofibers for High-Performance Asymmetric Supercapacitor Device. Sci. Rep. 2022, 12, 14919. [Google Scholar] [CrossRef]
  60. Ahangari, M.; Mahmoodi, E.; Delibaş, N.; Mostafaei, J.; Asghari, E.; Niaei, A. Application of SrFeO3 Perovskite as Electrode Material for Supercapacitor and Investigation of Co-Doping Effect on the B-Site. Turk. J. Chem. 2022, 46, 1723–1732. [Google Scholar] [CrossRef]
  61. Liu, L.; Liu, G.; Wu, S.; He, J.; Zhou, Y.; Demir, M.; Huang, R.; Ruan, Z.; Jiang, G.; Ma, P. Fe-Substituted SrCoO3 Perovskites as Electrode Materials for Wide Temperature-Tolerant Supercapacitors. Ceram. Int. 2024, 50, 1970–1980. [Google Scholar] [CrossRef]
  62. Shafi, P.M.; Mohapatra, D.; Reddy, V.P.; Dhakal, G.; Kumar, D.R.; Tuma, D.; Brousse, T.; Shim, J.-J. Sr-and Fe-Substituted LaMnO3 Perovskite: Fundamental Insight and Possible Use in Asymmetric Hybrid Supercapacitor. Energy Storage Mater. 2022, 45, 119–129. [Google Scholar] [CrossRef]
  63. George, G.; Jackson, S.L.; Luo, C.Q.; Fang, D.; Luo, D.; Hu, D.; Wen, J.; Luo, Z. Effect of Doping on the Performance of High-Crystalline SrMnO3 Perovskite Nanofibers as a Supercapacitor Electrode. Ceram. Int. 2018, 44, 21982–21992. [Google Scholar] [CrossRef]
  64. Tomar, A.K.; Singh, G.; Sharma, R.K. Fabrication of a Mo-Doped Strontium Cobaltite Perovskite Hybrid Supercapacitor Cell with High Energy Density and Excellent Cycling Life. ChemSusChem 2018, 11, 4123–4130. [Google Scholar] [CrossRef] [PubMed]
  65. Ajin, I.; Balamurugan, R.; Chandra Bose, A. Tailoring the Perovskite Structure to Acquire an Inorganic La2NiCrO6 Double Perovskite as an Efficient Energy Storage Application by Varying Molar Concentrations of Citric Acid. ACS Appl. Energy Mater. 2023, 6, 9764–9777. [Google Scholar] [CrossRef]
  66. Zhang, Y.; Ding, J.; Xu, W.; Wang, M.; Shao, R.; Sun, Y.; Lin, B. Mesoporous LaFeO3 Perovskite Derived from MOF Gel for All-Solid-State Symmetric Supercapacitors. Chem. Eng. J. 2020, 386, 124030. [Google Scholar] [CrossRef]
  67. Raj, T.V.; Hoskeri, P.A.; Muralidhara, H.B.; Manjunatha, C.R.; Kumar, K.Y.; Raghu, M.S. Facile Synthesis of Perovskite Lanthanum Aluminate and Its Green Reduced Graphene Oxide Composite for High Performance Supercapacitors. J. Electroanal. Chem. 2020, 858, 113830. [Google Scholar] [CrossRef]
Figure 1. Schematic diagram of material synthesis.
Figure 1. Schematic diagram of material synthesis.
Batteries 11 00310 g001
Figure 2. (a) XRD, (b) FTIR and (c) PL spectra of both ORJ and LMJ. XRD refinement of (d) ORJ with a single perovskite phase and (e) LMJ with both the perovskite and Fe2O3 phase.
Figure 2. (a) XRD, (b) FTIR and (c) PL spectra of both ORJ and LMJ. XRD refinement of (d) ORJ with a single perovskite phase and (e) LMJ with both the perovskite and Fe2O3 phase.
Batteries 11 00310 g002
Figure 3. Morphological images of perovskite (a,b) ORJ and (d,e) LMJ showing irregularly shaped connected particles. The elemental analysis of (c) ORJ and (f) LMJ confirms the presence of all the elements.
Figure 3. Morphological images of perovskite (a,b) ORJ and (d,e) LMJ showing irregularly shaped connected particles. The elemental analysis of (c) ORJ and (f) LMJ confirms the presence of all the elements.
Batteries 11 00310 g003
Figure 4. CV curves of (a) ORJ and (b) LMJ measured at different scan rates. (c) The specific capacity values are expressed as a function of the scan rate for both electrodes. GCD curves of (d) ORJ and (e) LMJ measured at different current densities. (f) The specific capacity values are expressed as a function of the current density for both electrodes. (g) CV comparison curve of LMJ and ORJ at 1 mV/s scan rate. (h) GCD comparison curve of LMJ and ORJ at 1 A/g current density.
Figure 4. CV curves of (a) ORJ and (b) LMJ measured at different scan rates. (c) The specific capacity values are expressed as a function of the scan rate for both electrodes. GCD curves of (d) ORJ and (e) LMJ measured at different current densities. (f) The specific capacity values are expressed as a function of the current density for both electrodes. (g) CV comparison curve of LMJ and ORJ at 1 mV/s scan rate. (h) GCD comparison curve of LMJ and ORJ at 1 A/g current density.
Batteries 11 00310 g004
Figure 5. (a) Cyclic stability of LMJ for 2500 GCD cycles. (b) The Nyquist graph obtained from EIS is plotted between real impedance on the x-axis and imaginary impedance on the y-axis for both electrodes. The Bode plot for (c) LMJ and (d) ORJ shows a plot of impedance and phase angle as a function of frequency.
Figure 5. (a) Cyclic stability of LMJ for 2500 GCD cycles. (b) The Nyquist graph obtained from EIS is plotted between real impedance on the x-axis and imaginary impedance on the y-axis for both electrodes. The Bode plot for (c) LMJ and (d) ORJ shows a plot of impedance and phase angle as a function of frequency.
Batteries 11 00310 g005
Figure 6. (a,b) b-value calculation for LMJ and ORJ, respectively, from the graph plotted between log peak current versus log scan rate. Outer and inner charge calculation for (c,d) ORJ and (e,f) LMJ using the Trassati Method. (g,h) R2 value graph for the fabricated electrodes to check the reversibility of the electrode.
Figure 6. (a,b) b-value calculation for LMJ and ORJ, respectively, from the graph plotted between log peak current versus log scan rate. Outer and inner charge calculation for (c,d) ORJ and (e,f) LMJ using the Trassati Method. (g,h) R2 value graph for the fabricated electrodes to check the reversibility of the electrode.
Batteries 11 00310 g006
Figure 7. The figure shows the capacitive contribution part from experimental CV data at a 5 mV/s scan rate for (a) ORJ and (b) LMJ. Capacitive and diffusive contributions at each scan rate for (c) ORJ and (d) LMJ.
Figure 7. The figure shows the capacitive contribution part from experimental CV data at a 5 mV/s scan rate for (a) ORJ and (b) LMJ. Capacitive and diffusive contributions at each scan rate for (c) ORJ and (d) LMJ.
Batteries 11 00310 g007
Figure 8. The schematic diagram shows the mixed-phase Sr0.8Ce0.2Fe0.8Co0.2O3 perovskite and Fe2O3 structure.
Figure 8. The schematic diagram shows the mixed-phase Sr0.8Ce0.2Fe0.8Co0.2O3 perovskite and Fe2O3 structure.
Batteries 11 00310 g008
Figure 9. (a) CV curves of the positive (LMJ) and negative electrode (A.C.) to determine the working potential of the electrode. (b) CV and (c) GCD curves of the fabricated LMJ||AC device. (d) Specific capacity values are obtained at different current densities. (e) Capacitance retention and coulombic efficiency over 5000 cycles are expressed in the graph plot. (f) Nyquist plot obtained from EIS before and after 5000 GCD cycles.
Figure 9. (a) CV curves of the positive (LMJ) and negative electrode (A.C.) to determine the working potential of the electrode. (b) CV and (c) GCD curves of the fabricated LMJ||AC device. (d) Specific capacity values are obtained at different current densities. (e) Capacitance retention and coulombic efficiency over 5000 cycles are expressed in the graph plot. (f) Nyquist plot obtained from EIS before and after 5000 GCD cycles.
Batteries 11 00310 g009
Table 1. Parameters obtained from Rietveld refinement.
Table 1. Parameters obtained from Rietveld refinement.
MaterialR-FactorsχRCNBVS
RpRwpRexp
ORJSr-O12.515.713.91.272.76122.12
Fe-O1.9563.56
LMJSr-O13.316.715.41.182.74122.20
Fe-O1.9463.70
Table 2. Comparison of synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 with the reported literature.
Table 2. Comparison of synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 with the reported literature.
Sr. NoMaterialSynthesis
Method
ElectrolyteCapacityCapacitanceRef.
1SrCo0.5Fe0.5O3Sol–gel1 M KOH-219 F/g at 2 A/g[60]
2SrFe0.8Co0.2O3Combustion Sol–gel1 M KOH-433 F/g at 2 A/g[28]
3SrCo0.9Fe0.1O3-δSolid-state Reaction1 M NaOH-526 F/g at 1 A/g[61]
4La 0.7Sr0.3Mn0.5Fe0.5O3Sol–gel Auto-combustion3 M KOH330 C/g at 1 A/g-[62]
5SrFe0.85Zr0.15O3-δSolid-state Reaction2 M KOH-163 F/g at 0.5 A/g[29]
6Sr 0.8Ce 0.2Fe0.8Co0.2O3 (ORJ),
(LMJ)
Auto-combustion1 M KOH158 C/g,
300 C/g at 1 A/g
300 F/g,
544 F/g at 1 A/g
This work
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Fazal, A.; Iqbal, M.J.; Raza, M.A.; Almutairi, B.S.; Zakaly, H.M.H.; Akhtar, N.; Irshad, M.; Riaz, S. Exploring the Potential of Green Synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 Using Orange and Lemon Extracts for Hybrid Supercapacitor Applications. Batteries 2025, 11, 310. https://doi.org/10.3390/batteries11080310

AMA Style

Fazal A, Iqbal MJ, Raza MA, Almutairi BS, Zakaly HMH, Akhtar N, Irshad M, Riaz S. Exploring the Potential of Green Synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 Using Orange and Lemon Extracts for Hybrid Supercapacitor Applications. Batteries. 2025; 11(8):310. https://doi.org/10.3390/batteries11080310

Chicago/Turabian Style

Fazal, Asmara, M. Javaid Iqbal, Mohsin Ali Raza, Badriah S. Almutairi, Hesham M. H. Zakaly, Naureen Akhtar, Muneeb Irshad, and Saira Riaz. 2025. "Exploring the Potential of Green Synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 Using Orange and Lemon Extracts for Hybrid Supercapacitor Applications" Batteries 11, no. 8: 310. https://doi.org/10.3390/batteries11080310

APA Style

Fazal, A., Iqbal, M. J., Raza, M. A., Almutairi, B. S., Zakaly, H. M. H., Akhtar, N., Irshad, M., & Riaz, S. (2025). Exploring the Potential of Green Synthesized Sr0.8Ce0.2Fe0.8Co0.2O3 Using Orange and Lemon Extracts for Hybrid Supercapacitor Applications. Batteries, 11(8), 310. https://doi.org/10.3390/batteries11080310

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop