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Abstract Electrochemical energy storage devices with high specific capacity are of utmost important for the next-generation electronic devices. Supercapatteries (SCs) are highly demanded energy storage devices nowadays as these bridge the low energy supercapacitors and low power batteries. Herein, we report a rapid synthesis of cobalt manganese phosphate (COMAP) by microwave-assisted hydrothermal method and facile fabrication of SCs using electrodes comprising of COMAP as positrode material. The effect of precursor concentration on the microstructure and surface morphology of the COMAP samples are examined initially. Further, the electrochemical performance of COMAP electrodes is studied systematically in 3 M KOH (aqueous) electrolyte. COMAP exhibits excellent charge storage capabilities where type of charge storage mechanism is found to be battery-type based on the calculation obtained from Dunn’s method. The SC electrode fabricated with COMAP synthesized using cobalt: manganese precursor ratio as 80:20 exhibits a highest specific capacity of 191.4 C/g at a scan rate of 1 mV/s. An asymmetric SC (ASC) cell fabricated with COMAP as positrode and activated carbon (AC) as negatrode exhibits a specific capacity of 165.5 C/g at a current density of 1.8 A/g. The COMAP//AC ASC cell exhibits an energy density of 34.1 Wh/kg at a corresponding power density of 1875 W/kg at a current density of 1.8 A/g.

Abstract New generation of electrochemical energy storage devices (EESD) such as supercapattery is being intensively studied as it merges the ideal energy density of batteries and optimal power density of supercapacitors in a single device. A multitude of parameters such as the method of electrodes preparation can affect the performance of supercapattery. In this research, nickel doped tin sulfide /tin oxide (SnS@Ni/SnO2) heterostructures were grown directly on the Ni foam and subjected to different calcination temperatures to study their effect on formation, properties, and electrochemical performance through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and electrochemical tests. The optimized SnS@Ni/SnO2 electrode achieved a maximum specific capacity of 319 C g− 1 while activated carbon based capacitive electrode exhibited maximum specific capacitance of 381.19 Fg− 1. Besides, capacitive electrodes for the supercapattery were optimized by incorporating different conductive materials such as acetylene black (AB), carbon nanotubes (CNT) and graphene (GR). Assembling these optimized electrodes with the aid of charge balancing equation, the assembled supercapattery was able to achieve outstanding maximum energy density and power density of 36.04 Wh kg− 1 and 12.48 kW kg− 1 with capacity retention of 91% over 4,000 charge/discharge cycles.

Metal sulfide-based composites have become increasingly common as materials used for electrodes in supercapacitors because of their excellent conductivity, electrochemical activity, and redox capacity. This study synthesized a composite of NiFeS@MoS2@rGO nanostructure using a simple hydrothermal approach. The synthesized nanocomposite consisted of the composite of nickel sulfide and iron sulfide doped with MoS2@rGO. A three-electrode cell is employed to investigate the electrochemical properties of the NiFeS@MoS2@rGO electrode. The results demonstrated an optimal specific capacitance of 3188 F/g at 1.4 A/g in a 1 M KOH electrolyte. Furthermore, a supercapattery is designed utilizing NiFeS@MoS2@rGO//AC as the positive electrode and activated carbon (AC) as the negative electrode materials. The resulting supercapattery is designed at a cell voltage of 1.6 V, achieving a specific capacity value of 189 C/g at 1.4 A/g. It also demonstrated an excellent energy density of 55 Wh/kg with an enhanced power density of 3800 W/kg. Furthermore, the hybrid device demonstrated remarkable stability with a cycling stability of 95% over 30,000 charge–discharge cycles at a current density of 1.4 A/g. The supercapattery, which has excellent energy storage capabilities, is used as a power source for operating different portable electronic devices. [ABSTRACT FROM AUTHOR]

Electrochemical energy storage devices with high specific capacity are of utmost important for the next-generation electronic devices. Supercapatteries (SCs) are highly demanded energy storage devices nowadays as these bridge the low energy supercapacitors and low power batteries. Herein, we report a rapid synthesis of cobalt manganese phosphate (COMAP) by microwave-assisted hydrothermal method and facile fabrication of SCs using electrodes comprising of COMAP as positrode material. The effect of precursor concentration on the microstructure and surface morphology of the COMAP samples are examined initially. Further, the electrochemical performance of COMAP electrodes is studied systematically in 3 M KOH (aqueous) electrolyte. COMAP exhibits excellent charge storage capabilities where type of charge storage mechanism is found to be battery-type based on the calculation obtained from Dunn's method. The SC electrode fabricated with COMAP synthesized using cobalt: manganese precursor ratio as 80:20 exhibits a highest specific capacity of 191.4 C/g at a scan rate of 1 mV/s. An asymmetric SC (ASC) cell fabricated with COMAP as positrode and activated carbon (AC) as negatrode exhibits a specific capacity of 165.5 C/g at a current density of 1.8 A/g. The COMAP//AC ASC cell exhibits an energy density of 34.1 Wh/kg at a corresponding power density of 1875 W/kg at a current density of 1.8 A/g. [ABSTRACT FROM AUTHOR]

New generation of electrochemical energy storage devices (EESD) such as supercapattery is being intensively studied as it merges the ideal energy density of batteries and optimal power density of supercapacitors in a single device. A multitude of parameters such as the method of electrodes preparation can affect the performance of supercapattery. In this research, nickel doped tin sulfide /tin oxide (SnS@Ni/SnO2) heterostructures were grown directly on the Ni foam and subjected to different calcination temperatures to study their effect on formation, properties, and electrochemical performance through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and electrochemical tests. The optimized SnS@Ni/SnO2 electrode achieved a maximum specific capacity of 319 C g− 1 while activated carbon based capacitive electrode exhibited maximum specific capacitance of 381.19 Fg− 1. Besides, capacitive electrodes for the supercapattery were optimized by incorporating different conductive materials such as acetylene black (AB), carbon nanotubes (CNT) and graphene (GR). Assembling these optimized electrodes with the aid of charge balancing equation, the assembled supercapattery was able to achieve outstanding maximum energy density and power density of 36.04 Wh kg− 1 and 12.48 kW kg− 1 with capacity retention of 91% over 4,000 charge/discharge cycles. [ABSTRACT FROM AUTHOR]

The rational design of electrode materials is pivotal for optimizing the performance of energy storage and conversion systems such as supercapattery and electrocatalysis. In this study, a one‐step supercritical fluid synthesis is presented to craft a unique heteroepitaxial composite, incorporating nickel di‐selenide nanoparticles on niobium carbide MXene nanosheets in various ratios. The integration of 2D nanosheets enhances the kinetics of the electrode reaction process, while NiSe2 facilitates efficient charge transport in MXene. The composite demonstrated superior performance with the 1:2 ratio of NiSe2/Nb2CTx demonstrates an impressive specific capacitance of 1309 C g−1 at 2 A g−1 current density in a three‐electrode system. Furthermore, the asymmetric supercapattery, featuring NiSe2/Nb2CTx 1:2 (positive electrode) and bio‐derived activated carbon (AC) (negative electrode) achieves a gravimetric capacitance of 205 C/g at 0.5 A g−1 current density, a power density of 10,800 W kg−1 at the energy density of 64 Wh kg−1, with 90% retention after 12 000 cycles. As a catalyst for water oxidation, the NiSe2/Nb2CTx 1:2 exhibits the lowest over potential of 359 mV at the current density 10 mA cm−2 and Tafel slope of 105 mV dec−1. This investigation introduces an innovative approach for developing high‐performance supercapattery electrode materials and electrocatalysts using MXene. [ABSTRACT FROM AUTHOR]

The electrode materials are essential to fabricate energy storage systems. Here, the electrode materials of LiNiPO4 Nanoparticles (NPs) were prepared using simple hydrothermal process and its structural, morphology, functional and elemental properties were confirmed with special analytical tools like, powder X-ray diffraction (PXRD), Scanning electron microscope (SEM), Furrier transform infrared spectroscopy (FTIR) and energy dispersive X- ray diffraction (EDX) with mapping correspondingly. Ensuing the redox peaks and electrochemical interaction, charge/discharge cycles and conductivity of electrode materials were examined through the cyclic voltammetry (CV), Galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies. The prepared LiNiPO4 electrodes exhibit a superior specific capacity of 651.70 C/g at 5 mV/s. The cyclic stability of electrode attained 87 % specific-capacity retention complete 10,000 cycles with 5 A/g.

Various binary and ternary oxide nanomaterials have been described in the literature for charge storage applications. Recently, tellurium-based compounds are being explored for supercapacitor applications due to their high and tunable electrical conductivity and structural stability as well as less toxicity. In this work, pure copper tellurate (Cu3TeO6) nanopowder is synthesized by a coprecipitation method, and an electrode is prepared by brush-coating Cu3TeO6 nanoparticles on Ni foam. The structural and phase analysis of Cu3TeO6 nanoparticle is studied by X-ray diffraction, Fourier transform infrared, and Raman spectroscopy. The oxidation states of metal ions in the sample are determined by X-ray photoelectron spectroscopy analysis. The three-dimensional (3-D) spin-web structure of Cu3TeO6 nanoparticles allows fast electron transport while maintaining structural integrity during electrochemical reactions. The Cu3TeO6 electrode shows a specific capacity of 578 C g–1 (specific capacitance; 1157 F g–1) at 1 A g–1 and maintains a high rate capability with a specific capacity of 111 C g–1 (specific capacitance; 221 F g–1) at 150 A g–1. The electrode performance during 40,000 unceasing charge–discharge cycles at 40 A g–1 has 100% Coulombic efficiency with commendable stability and more than 100% capacitance retention. Furthermore, a Cu3TeO6∥AC (AC = activated carbon) asymmetric device is constructed that exhibits a 5.4 W h kg–1 energy density and 7505 W kg–1 power density. The device Cu3TeO6∥AC exhibits high storage performance with 98% capacitance retention up to 8000 cycles at 10 A g–1. The unique charge storage performance of Cu3TeO6 nanoparticle is credited to its synergistic effect coming from the stable CuO-TeO2 and 3-D network-like structure and low electrode charge transfer resistance. Among various Te-based compounds, the Cu3TeO6 nanoparticle holds potential as an oxide material suitable for the development and advancement of high-performance battery-type supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] Binary metal phosphate electrodes have been widely studied for energy storage applications due to the synergistic effects of two different transition elements that able to provide better conductivity and stability. Herein, the battery-type binder-free nickel-manganese phosphate (NiMn-phosphate) electrodes were fabricated with different Ni:Mn precursor ratios via microwave-assisted hydrothermal technique for 5 min at 90 °C. Overall, NiMn3P electrode (Ni:Mn = 1:3) showed an outstanding electrochemical performance, displaying the highest specific (areal) capacity at 3 A/g of 1262.4 C/g (0.44 C/cm2), and the smallest charge transfer resistance of 108.8 Ω. The enhanced performance of NiMn3P electrode can be ascribed to the fully grown amorphous nature and small-sized flake and flower structures of NiMn3P electrode material on the nickel foam (NF) surface. This configuration offered a higher number of active sites and a larger exposed area, facilitating efficient electrochemical reactions with the electrolyte. Consequently, the NiMn3P//AC electrode combination was chosen to further investigate its performance in supercapattery. The NiMn3P//AC supercapattery exhibited remarkable energy density of 105.4 Wh/kg and excellent cyclic stability with 84.7% retention after 3000 cycles. These findings underscored the superior electrochemical performance of the battery-type binder-free NiMn3P electrode, and highlight its potential for enhancing the overall performance of supercapattery. [ABSTRACT FROM AUTHOR]

The overconsumption of fossil fuels is leading to worsening environmental damage, making the generation of clean, renewable energy an absolute necessity. Two common components of electrochemical energy storage (EES) devices are batteries and supercapacitors (SCs), which are among the most promising answers to the worldwide energy issue. In this study, we introduce an exceptionally efficient electrode material for supercapacitors, composed of a hydrothermally synthesized composite known as MnNiS@MXene. We utilized XRD, SEM, and BET to analyze the material's crystallinity, morphology, and surface area. The Qs of MnNiS@MXene was a remarkable 1189.98 C/g or 1983.3 F/g at 2 A/g under three electrode assemblies in 1 M KOH electrolyte solution. Activated carbon was used as the negative electrode, while MnNiS@MXene served as the positive electrode in the assembled supercapattery device (MnNiS@MXene//AC). This device showed exceptional performance, a specific capacity of 307.18 C/g, a power density of 1142.61 W/kg, and an energy density of 34.79 Wh/kg. Additionally, cyclic durability was evaluated through 7000 cycles of charging/discharging, demonstrating that it maintained approximately 87.57% of its original capacity. The successful integration of these materials can lead to electrodes with superior energy storage capabilities and efficient photoelectrochemical performance. The aforementioned findings suggest that MnNiS@MXene exhibits promising potential as an electrode material for forthcoming energy storage systems. [ABSTRACT FROM AUTHOR]

A practical supercapattery electrode with photocatalytic efficiency is created using tunnel-structured manganese dioxide nanostructure intercalated with K+ ions ∝ - K 0.18 MnO 2 through a single-step hydrothermal method. The tunnel structure and the high surface area of the material facilitate the interaction of ions, increasing the number of active sites and thereby enhancing the electrochemical and photocatalytic performance. The nanostructure exhibits a tetragonal hollandite structure with well-defined nanorod morphology. The prepared sample shows intriguing results in Raman spectra across various laser wavelength inputs. The examination of pore characteristics of the material revealed mainly mesopores throughout the sample. Optical examinations conducted using UV visible spectra revealed an energy band gap of 1.08 eV. The multiple oxidation states of the manganese were determined through X-ray photoelectron spectroscopy analysis, along with the existence of various oxygen components. The electrochemical performance of the optimized sample was assessed using a three-electrode assembly in 1 M KOH, which showed a high specific capacity of 577.33 C g−1 at 0.5 A g−1, confirmed using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) analysis. The cyclic stability of the electrode was tested, showing 79.6% capacitance retention with 99.84% coulombic efficiency over 5000 charge–discharge cycles at 15 A g−1. The capacitive and diffusive contributions of the electrode material were evaluated using the power law and Dunn's method. The dye degradation efficiency of the nanocatalyst, tested over crystal violet dye, showed 98.7% degradation even after sunlight irradiation. These multifunctional applications of MnO2 pave the way to develop hybrid nanocomposites for extended applications. [ABSTRACT FROM AUTHOR]

Energy sources play a crucial role in the development of the society. The gargantuan depletion of fossil fuels creates new glitches in the routine activities of human beings. Electrocatalysts can efficiently produce and store energy and, therefore, have the potential to alleviate this situation. A multifunctional electrocatalyst, Poly (3,4‐ethylenedioxythiophene)/cobalt oxide‐cerium oxide(PEDOT/Co3O4‐CeO2), is synthesized by incorporating mixed metal oxide to 3,4‐ethylenedioxythiophene (EDOT) using the in situ chemical oxidative polymerization method and is employed for both energy production and storage applications. The successful synthesis of the catalyst is confirmed through various characterization techniques. The composite shows a specific capacity of 617.8 C g−1 and a specific capacitance value of 1298.1 F g−1. The hydrogen evolution reaction (HER) analysis shows that the composite requires a low overpotential of 163.1 mV at a current density of 10 mA cm−2. Synthesized electrocatalysts can effectively handle the energy related issues prevailing in the society. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated the influence of cobalt oxalate hydrate (CoC2O4.nH2O), the working electrode for supercapattery. A binder-free electrode composed of CoC2O4.nH2O synthesized directly on the nickel foam via hydrothermal method. L-ascorbic acid (LAA) was used as a morphology-directing green-reducing agent and as an oxalate source. The structural characterization was rationalized by studying the effect of reaction time on the growth of CoC2O4.nH2O. The electrodes prepared using 8, 10, 12, and 14 drops of potassium hydroxide (KOH) were heated for 6 h. The optimized sample was then selected and heated for 24 h. The crystallinity of the electrode increased with increasing hydrothermal reaction time. In electrochemical measurements, the effects of heating time and different drops of KOH on the formation of different cobalt oxalate hydrates were discussed in detail. The electrode prepared using 10 drops of KOH followed by 6 h of heating process exhibited excellent specific capacity/capacitance even at 10 A g−1 (575 C g−1/1203.64 F g−1) with maximum energy density and power density of 59 Wh kg−1 and 2389 W kg−1, respectively. The supercapattery using CoC (10) exhibited splendid capacity retention of 102% over 10,000 cycles confirming its suitability as a battery-type electrode for supercapattery. [ABSTRACT FROM AUTHOR]

Flexible graphene‐based paper electrodes (FGPEs) are a new class of study and the research on this electrode material has been carried out for approximately ten years. FGPEs have many advantages compared to classical solid electrodes such as being flexible, foldable, adaptable to flexible electronics, being cut, easily shaped, and effective and adjustable modification. In this work, the applicability of FGPEs modified with polyindole (PIN) thin films and zinc oxide nanoparticles (ZnO‐NPs) to energy‐storage systems as a supercapattery design is presented, and especially the limitations of ZnO‐NPs for energy‐storage applications are revealed to inform researchers working for a similar purpose. Capacitance calculations have been performed using both cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD) experiments. It was observed that the rGO/PIN paper demonstrated almost 30 times more energy‐storage capacity than that of the rGO/PIN/ZnO paper due to the electrochemical instability of ZnO‐NPs on the flexible electrode platform at the applied potential region in 1.0 M HClO4 solution. The rGO/PIN paper with a highly flexible property exhibited an energy density of 74.5 W h cm−2 and a power density of 2258 W cm−2 at a current density of 2.2 mA cm−2, revealing hopeful results for future modular and flexible approaches. [ABSTRACT FROM AUTHOR]

A supercapattery is an advanced energy storage device with superior power and energy density compared to traditional supercapacitors and batteries. A facial and single-step hydrothermal method was adopted to synthesize the rGO/GQDs doped Fe-MOF nano-composites. The incorporation of the dopants into the host material was to improve the energy storage capacity and improve cyclic stability. The structural, morphological, and compositional analyses were conducted by employing X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Additionally, Brunauer–Emmett–Teller (BET) measurements were used to calculate the nanomaterial's surface area and pore size. Dunn's model was used to demonstrate the contributions of the capacitive and diffusive components of the asymmetric energy storage structure. Fe-MOF/rGO/GQDs have a higher specific capacity (1876 C/g) than pure Fe-MOF (705 C/g) at 1.0 A/g current density. The Fe-MOF/rGO/GQDs supercapattery retained 95% of its capacity after 5000 charging and discharging cycles to test the asymmetric device durability. The power and energy densities have been determined to be 1160 W/kg and 57 Wh/kg, respectively. Fe-MOF showed excellent electrocatalytic activity in the hydrogen evolution process (HER) with a declined Tafel slope of 47.27 mV/dec. The Fe-MOF/rGO/GQDs electrode exhibits the lowest overpotential of 278 mV at 10 mA cm−2 with a Tafel slope of roughly 49.2 mV dec−1 in its function as an oxygen evolution reaction (OER) catalyst. This research work provides a basis for improving the efficiency of energy storage technologies. [ABSTRACT FROM AUTHOR]

Nickel cobalt layered double hydroxides (NiCo LDHs) have emerged as ideal electrode materials for supercapattery due to their high specific surface area and excellent cycling stability. Morphology control plays a unique role in regulating the performance of the NiCo LDHs. Herein, the morphology of NiCo‐LDHs electrode is optimized for enhancing energy storage by a simple activation process with different concentrations of the electrolyte. During the activation process, electrochemical morphology reconstruction occurs on the electrode surface. With a 2 m KOH electrolyte, the NiCo‐LDH electrode transforms from nanosheets to nanoflower, which aids in reducing the distance of ion transport. The reconstructed NiCo‐LDH exhibits an ultra‐high specific capacity of 2809 C g−1 at a current density of 1 A g−1, outperforming most of NiCo LDHs. At a high current density of 10 A g−1, the capacity retention rate remains above 72.7% after 3000 cycles. An asymmetric supercapacitor is fabricated with activated carbon material as the negative electrode, the energy density is 36 Wh kg−1 at the power density of 732 W kg−1. The strategy proposed in the study, which involves concentration‐controlled morphology optimization for energy storage enhancement, holds great practical significance for the field of supercapatteries. [ABSTRACT FROM AUTHOR]

Conducting polymers have attained a lot of interest due to extraordinary conductivity, large pore size, and surprising stability. In this work, the conducting polymer polyaniline (PANI) and niobium sulfide (NbS) were synthesized by polymerization of aniline and hydrothermal method, respectively. The PANI@NbS nanocomposite electrode material had a specific capacity (Cs) of 1050 C g−1, which is larger than that of the reference sample (NbS = 300 C g−1). Besides, the hybrid device (PANI@NbS//PANI@AC) was designed and the electrochemical characteristics were determined. The hybrid device showed an excellent value of Cs of 1207 C g−1 with higher energy density Ed and power density Pd. The device also exhibited remarkable stability, and 85 % of the initial capacity is retained after 1000 cycles. [ABSTRACT FROM AUTHOR]

Nowadays, immense attention has been paid toward the rational design and synthesis of high-power density electrodes materials for high-power supercapattery applications. In the present work, ZnFe2O4 nanostructures with unique cauliflower-like morphology were deposited on a flexible nickel foam substrate using a simple, cost-effective, and environmentally friendly electrodeposition method. The synthesized nanostructures were thoroughly examined by using structural, morphological, and electrochemical characterization techniques. Electrochemical studies of cauliflower-like nanostructured ZnFe2O4 electrode show a deviation from normal behavior and favored a mixed supercapacitor-battery-type nature. The value of specific capacity is obtained as 513 C g−1 at a current density of 1 Ag−1. The cauliflower-like nanostructured ZnFe2O4 electrode exhibits remarkable energy density and power density of 8.72 Wh kg−1 and 306.25 W kg−1 , respectively. Also, it shows long-term cyclic stability up to 5000 cycles with a maximum capacitance retention rate of 72%. These results signify that the high electrochemical performance and excellent stability of the cauliflower-like nanostructured ZnFe2O4 electrode material relate to their unique architecture, high energy, and power density for supercapattery devices. [ABSTRACT FROM AUTHOR]

Abstract Nickel cobalt layered double hydroxides (NiCo LDHs) have emerged as ideal electrode materials for supercapattery due to their high specific surface area and excellent cycling stability. Morphology control plays a unique role in regulating the performance of the NiCo LDHs. Herein, the morphology of NiCo‐LDHs electrode is optimized for enhancing energy storage by a simple activation process with different concentrations of the electrolyte. During the activation process, electrochemical morphology reconstruction occurs on the electrode surface. With a 2 m KOH electrolyte, the NiCo‐LDH electrode transforms from nanosheets to nanoflower, which aids in reducing the distance of ion transport. The reconstructed NiCo‐LDH exhibits an ultra‐high specific capacity of 2809 C g−1 at a current density of 1 A g−1, outperforming most of NiCo LDHs. At a high current density of 10 A g−1, the capacity retention rate remains above 72.7% after 3000 cycles. An asymmetric supercapacitor is fabricated with activated carbon material as the negative electrode, the energy density is 36 Wh kg−1 at the power density of 732 W kg−1. The strategy proposed in the study, which involves concentration‐controlled morphology optimization for energy storage enhancement, holds great practical significance for the field of supercapatteries.

[Display omitted] • Interconnected wrinkled microsphere (ICWMS) of Cu 2-x Se/Ni 1-x Se electrode was prepared. • It afforded excellent mesoporous properties with surface area of 148.5 m2g−1. • The Cu 2-x Se/Ni 1-x Se//AC cell achieved high capacity of 87.5 mAhg−1 @ 1Ag−1. • Excellent power and energy densities of 450 Wkg−1 and 39.3 Whkg−1 were achieved. Developing a rational design of nanoarchitechtures with excellent electrochemical behaviors is an ultimate and unique strategy to enhance the redox electrokinetics of battery-type electrode materials. Herein, we demonstrate a hierarchical composite comprising interconnected wrinkled micro-solid sphere (ICWMS)-like binary copper selenide/nickel selenide over nickel foam (Cu 2-x Se/Ni 1-x Se/NF) prepared via a wet chemical synthetic protocol and utilized as an effective positrode for improved supercapaterry performance. The binary Cu 2-x Se/Ni 1-x Se/NF electrode considerably improved the electroactive surface area and facilitated ultrafast redox electrochemistry in an alkaline electrolyte medium. Remarkably, the binary Cu 2-x Se/Ni 1-x Se/NF electrode afforded the highest specific capacity of 368 ± 1C/g at 1 A/g greater than that of pristine single selenide electrodes (Cu 2 Se and NiSe) in a three-electrode setup which might be attributed to its large surface area, synergism between Ni and Cu, and specific morphology. Moreover, a coin cell supercapattery with the binary Cu 2-x Se/Ni 1-x Se/NF positrode and a porous activated carbon-on-nickel-foam negatrode was constructed, which exhibited excellent energy-storage characteristics in terms of capacity (87.5 ± 1 mAh/g), specific energy (39.3 Wh kg−1), specific power (450 W kg−1), and capacity retention (91.8 %). This simple fabrication approach of hierarchically designed Cu 2-x Se/Ni 1-x Se/NF paves the way for utilizing it as the promising positrode for high-performance supercapattery. [ABSTRACT FROM AUTHOR]

Metal negatrode supercapattery (MNSC) is an emerging technology that combines the high energy storage capabilities of batteries with the high‐power delivery of supercapacitors, thereby offering promising solutions for various applications, such as energy storage systems, electric vehicles, and portable electronics. This review article presents a comprehensive analysis of the potential of MNSCs as a prospective energy storage technology. MNSCs utilize a specific configuration in which the negatrode consists of a metal or metal‐rich electrode, such as sodium, aluminum, potassium, or zinc, whereas the positrode functions as a supercapacitor electrode. The utilization of negatrodes with low electrochemical potential and high electrical conductivity is crucial for achieving high specific energy in energy storage devices, despite facing numerous challenges. The present study discusses the design and fabrication aspects of MNSCs, including the selection of appropriate metal negatrodes, electrolytes, and positrodes, alongside the fundamental operational mechanisms. Additionally, this review explores the challenges encountered in MNSCs and proposes solutions to enhance their performance, such as addressing dendrite formation and instability of metal electrodes. [ABSTRACT FROM AUTHOR]

Supercapattery has drawn attention due to its superior tip-discharge efficiency and high energy density without affecting the cycle stability compared to conventional batteries and supercapacitors (SCs). Redox-active porous organic polymers (POPs) are regarded as promising energy storage materials due to the presence of overlapped π-electron clouds between the stacked layers, conjugated backbone, and high-rate charge transfer channels. However, single POPs material has fewer electroactive sites resulting from the broad and ordered π-π stacking in the network structure, limiting their corresponding electrochemical performance. In the present paper, Schiff base polymers containing ferrocene (Fc) and carbon nanotubes (CNTs) were prepared by one pot synthesis method for high-performance supercapattery. The microstructure studies exhibit that the CNTs were combined with the amorphous Schiff base polymer backbone. Moreover, the charge storage mechanism was discussed in detail. The electrochemical properties studies present that the sample (SPOP-Fc0.4/CNTs-5) possess the maximal specific capacitance (201.3 mAh g−1) at 0.5 A g−1 and the excellent specific capacity retention (retaining 84.3% of initial capacitance after 5000 GCD cycles at the current density of 10 A g−1). The enhanced performance shown by SPOP-Fc0.4/CNTs-5 was attributed to the synergy produced by the redox behavior and conjugated backbone provided by SPOP, the doping of Fc, and high-speed ion transport channels provided by CNTs. To evaluate the practicability of electrode materials, the asymmetric supercapattery devices (ASC) were assembled in a configuration of the SPOP-Fc0.4/CNTs-5//activated carbon (AC). SPOP-Fc0.4/CNTs-5//AC delivered a superb energy density of 65.9 Wh kg−1 with a power density of 344.8 W kg−1 while remaining almost 73.6% of the specific capacitance even after 5000 continuous GCD cycles. These Schiff-based POPs with advanced electrochemical capabilities deliver a fresh solution for material selection in energy storage, present extensively apply prospects in energy storage field. [ABSTRACT FROM AUTHOR]

Supercapattery has emerged as one of the possibilities in the electrochemical energy storage system as a consequence of the expansion of technological advancement and the electrical vehicle sector. Manganese sulfide (MnS) nanoflakes were produced by hydrothermal technique at various heating temperatures (100, 110, 120, and 130 °C). The existence of MnS is revealed by the X-ray diffraction (XRD) diffractogram, and α- and γ-MnS crystals were effectively grown on a nickel (Ni) foam. MnS nanoflakes were seen under a field emission scanning electron microscope (FESEM). The crystalline structure of MnS nanoflakes is susceptible to variation depending on the heating temperature, and at 120 °C, MnS produced nanoflakes with additional wrinkles. Through Brunauer–Emmett–Teller (BET) analysis, the thermal and physical adsorption investigations demonstrated the high total surface area and thermal stability of MnS electrodes. The findings of BET studies demonstrate that MnS-120 has the highest surface BET (SBET) and the smallest pore size distribution (PSD), which later increases the total surface area of MnS nanoflakes for an effective energy storage mechanism. MnS is structurally stable below 200 °C, according to thermogravimetric analysis (TGA). MnS-120 electrode has a maximum specific capacity of 1003.5 C/g at 5 A/g and a 49% rate capability. Supercapattery devices were created in a MnS-120//activated carbon (AC) configuration to assess the real-time performance of the material. The MnS-120//AC demonstrated better efficiency by offering a specific energy of 69.24 Wh/kg at 2953 W/kg. The life cycle test confirmed that MnS-120//AC is stable with a capacity retention value of 96% after 4000 cycles. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) derived nanostructures receive immense research focus due to its high porosity, conductivity, and structural tailrolability features. In this work, porous Zeolitic Imidazole Framework‐67 (ZIF‐67) to synthesize cobalt phosphide/carbon composite (ZCoPC) that serves as a positive electrode is utilized. Furthermore, porous and conductive office paper derived carbon (OPC) are utilized as a negative electrode to make a hybrid system. The metalloid characteristics, high conductivity, and good porosity of ZCoPC material makes it a high‐performance battery like electrode. ZCoPC electrode achieves maximum specific capacity of 192.6 mAh g−1 at 1 A g−1 using 1 m potassium hydroxide (KOH) electrolyte. Furthermore, surface and diffusion charge participation investigation are also undergone for ZCoPC electrode that helps in determining the actual charge dynamics occurring in the electrode. In addition, a supercapattery device is assembled using ZCoPC as battery electrode and OPC as supercapacitor electrode. The as fabricated OPC//ZCoPC hybrid supercapattery device delivers extraordinary energy density of 31.6 Wh kg−1 with a power density of 700 W kg−1 and also a long cycle life of 92.3% even after 10,000 charge–discharge cycles. Hence, these outcomes demonstrate that the synergy of porous MOF derived metal phosphide and OPC electrodes are beneficial for supercapattery devices. [ABSTRACT FROM AUTHOR]

The copper-based metal-organic framework (HKUST-1) exhibits interesting properties, such as high porosity and large specific surface area, which are useful as electrode materials for supercapattery. Herein, the HKUST-1 was synthesized through a facile hydrothermal method and exhibited a typical octahedral structure with a specific surface area of 1015.02 m2 g−1, which was calculated using the Barrett–Joyner–Halenda (BJH) method. From the three-electrode analysis, the HKUST-1 demonstrated a specific capacity of 126.2 C g−1 in 1 M LiOH. The structural fingerprint of the HKUST-1 was confirmed with Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction spectroscopy. A supercapattery device, i.e., the HKUST-1//N-doped graphene, revealed a maximum specific power of 300 W kg−1 and a specific energy of 2.61 W h kg−1 at 1 A g−1 with 57% capacitance retention during continuous charging–discharging, even after 10,000 cycles. The HKUST-1 also demonstrated a low charge transfer resistance and a low equivalent series resistance of 7.86 Ω and 0.87 Ω, respectively, verifying its good conductivity. The prominent supercapattery performance of the HKUST-1//N-doped graphene suggested that the HKUST-1 is a promising positive electrode for supercapattery. [ABSTRACT FROM AUTHOR]

Mixed multimetallic-based nanocomposites have been considered a promising functional material giving a new dimension to environmental remediation and energy storage applications. On this concept, a hybrid ternary CoO/Ni(OH)2/Cu(OH)2 (CNC) composite showing sea-urchin-like morphology was synthesized via one-pot hydrothermal approach, and its photocatalytic and electrochemical performances were investigated. The photocatalytic performance was explored using Congo red (CR) as a dye pollutant under visible light illumination. The presence of mixed phases of ternary metal ions could minimize the recombination efficacy of photogenerated charge carriers on the basis of the heterojunction mechanism, resulting in 90% degradation of CR dye (40 mg L−1). The effect of scavengers coupled with electrochemical experiments revealed O2−. radical as the predominating species responsible for the degradation of CR. From the electrochemical analysis of CNC, the well-distinguished redox peaks indicated the redox-type nature with a specific capacity of 405 C g−1. For practical applications, an supercapattery (CNC(+)|KOH|AC(−)) was assembled furnishing an energy density of 42 W h kg−1 at a power density of 5160 W kg−1 at 5 A g−1 along with a high capacity retention and coulombic efficiency of 98.83% over 5000 cycles. [ABSTRACT FROM AUTHOR]

Due to the high viability of electrochemical energy resources and their storage techniques in the present climate, supercapacitors and water-splitting electrolysis have seen dramatically increased attention in modern days. We presented the synthesis of nickel-copper phosphate (NiCu-PO x) nanosheets from the phosphorization of the nickel-copper metal-organic framework (NiCu-MOF) at a limited temperature. Further, the addition of nitrogen-doped graphene quantum dots (NGQD) in the Ni–Cu-PO x was also studied. SEM, XRD, and XPS were used to analyze the structural and elemental composition of the synthesized materials. Further, Brunauer-Emmett-Teller (BET) measurements showed an enhancement in surface area when NGQDs were introduced into the heterostructure of NiCu-PO x. An extraordinary value of specific capacity (1431 C -g−1 at 1.4 Ag-1) was achieved with NiCu-PO x /NGQDs. Supercapattery device (NiCu-PO x /NGQDs//PANI@AC) was fabricated with polyaniline doped activated carbon as the negative and NiCu-PO x /NGQDs as the positive electrode. The specific capacity of the real device (NiCu-PO x /NGQDs//PANI@AC) was 224 C -g−1 at 2.0 Ag-1. The energy density for this asymmetric device (NiCu-PO x /NGQDs//PANI@AC) was 73 Whkg−1 at 980 Wkg-1 power density. The device (NiCu-PO x /NGQDs//PANI@AC) was subjected to 10,000 charge-discharge cycles to test its durability. After 10,000 cycles NiCu-PO x /NGQDs//PANI@AC demonstrates an outstanding 86% reservation of capacity. The NiCu-POx/NGQDs showed a small overpotential of 138 mV during the 24 h HER test. According to our findings, NiCu-PO x /NGQDs proved to be a suitable electrode material for prospective supercapattery and HER applications. • The hydrothermal method was used to synthesize the Ni–Cu-MOF, Ni–Cu-PO x , and Ni–Cu-PO x /NGQD electrode material. • An extraordinary specific capacity of 1431 C -g−1 at 1.4 A g-1 current density was obtained. • The energy density calculated was found to be 73 Whkg−1. • The specific capacity of the real device was found to be 224 Cg-1. • It was observed that the 86% capacity was preserved after 10,000 cycles. [ABSTRACT FROM AUTHOR]

Synthesis of efficient electrocatalysts for energy applications is a major area scientists are currently focusing on to address the twin challenges of energy shortfall and the production of clean energy. Herein, an efficient electrocatalyst, polyaniline incorporated with polyethylene glycol capped CuO/TiO 2 is prepared, which is effective in hydrogen evolution reactions and energy storage applications. The characterizations like XPS, XRD, FT-IR, FE-SEM, HR-TEM, and BET have been carried out to confirm the successful formation of the synthesized PANI/CuO/TiO 2 composite. At 10 mA/cm2 current density, the prepared composite exhibits a lesser overpotential of 536 mV and 1587.2 C/g at 1 A/g as the specific capacity. The electrode prepared using the PANI/CuO/TiO 2 composite also shows cyclic stability up to 2000 cycles. The synthesized composite is an efficient electrocatalyst for energy related applications. [Display omitted] • PANI/CuO/TiO 2 was prepared using in situ chemical oxidative polymerization method. • PANI/CuO/TiO 2 composite showed both supercapattery and HER applications. • The composite showed good specific capacity of 1587.2C/g at 1 A/g. • The composite exhibited HER activity with a lower overpotential of 536 mV. [ABSTRACT FROM AUTHOR]

Highlights Incorporation of Schottky Junction increases the pseudocapacitive mechanism at higher current rate. The pseudocapacitance behavior of the positive and negative electrodes is balanced to construct a solid-state supercapattery device. An energy density of 236.14 Wh kg−1 is achieved for solid-state supercapattery device.

Abstract Metal–organic frameworks (MOFs) derived nanostructures receive immense research focus due to its high porosity, conductivity, and structural tailrolability features. In this work, porous Zeolitic Imidazole Framework‐67 (ZIF‐67) to synthesize cobalt phosphide/carbon composite (ZCoPC) that serves as a positive electrode is utilized. Furthermore, porous and conductive office paper derived carbon (OPC) are utilized as a negative electrode to make a hybrid system. The metalloid characteristics, high conductivity, and good porosity of ZCoPC material makes it a high‐performance battery like electrode. ZCoPC electrode achieves maximum specific capacity of 192.6 mAh g−1 at 1 A g−1 using 1 m potassium hydroxide (KOH) electrolyte. Furthermore, surface and diffusion charge participation investigation are also undergone for ZCoPC electrode that helps in determining the actual charge dynamics occurring in the electrode. In addition, a supercapattery device is assembled using ZCoPC as battery electrode and OPC as supercapacitor electrode. The as fabricated OPC//ZCoPC hybrid supercapattery device delivers extraordinary energy density of 31.6 Wh kg−1 with a power density of 700 W kg−1 and also a long cycle life of 92.3% even after 10,000 charge–discharge cycles. Hence, these outcomes demonstrate that the synergy of porous MOF derived metal phosphide and OPC electrodes are beneficial for supercapattery devices.

To make supercapattery devices feasible, there is an urgent need to find electrode materials that exhibit a hybrid mechanism of energy storage. Herein, we provide a first report on the capability of lithium manganese sulfates to be used as supercapattery materials at elevated temperatures. Two compositions are studied: monoclinic Li2Mn(SO4)2 and orthorhombic Li2Mn2(SO4)3, which are prepared by a freeze-drying method followed by heat treatment at 500 °C. The electrochemical performance of sulfate electrodes is evaluated in lithium-ion cells using two types of electrolytes: conventional carbonate-based electrolytes and ionic liquid IL ones. The electrochemical measurements are carried out in the temperature range of 20–60 °C. The stability of sulfate electrodes after cycling is monitored by in-situ Raman spectroscopy and ex-situ XRD and TEM analysis. It is found that sulfate salts store Li+ by a hybrid mechanism that depends on the kind of electrolyte used and the recording temperature. Li2Mn(SO4)2 outperforms Li2Mn2(SO4)3 and displays excellent electrochemical properties at elevated temperatures: at 60 °C, the energy density reaches 280 Wh/kg at a power density of 11,000 W/kg. During cell cycling, there is a transformation of the Li-rich salt, Li2Mn(SO4)2, into a defective Li-poor one, Li2Mn2(SO4)3, which appears to be responsible for the improved storage properties. The data reveals that Li2Mn(SO4)2 is a prospective candidate for supercapacitor electrode materials at elevated temperatures. [ABSTRACT FROM AUTHOR]

Supercapattery is an energy storage device which shows high power and energy densities compared to supercapacitors and batteries. A simple and cost‐effective sol‐gel method was used to synthesize the aluminium‐doped cobalt oxide (Al‐Co3O4). The structural, morphological and composition analyses were investigated using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). Further, Brunauer‐Emmett‐Teller (BET) calculations were performed, which showed an enhancement in surface area. The specific capacity of the Al‐doped sample was increased up to 708 C/g compared to the reference sample (Co3O4=420 C/g). A supercapattery device was designed by using the activated carbon as a negative electrode and the Al‐Co3O4 as the positive electrode in two electrode assemblies. The estimated value of the specific capacity of Al‐Co3O4 was 189 C/g. Furthermore, the obtained energy and power density values were 42 Wh/kg and 2080 W/kg, respectively. To investigate the stability, this device was subjected to 5000 charging/discharging cycles that maintained 90 % of its initial capacity. Our findings provide a foundation for improving the performance of energy storage devices. [ABSTRACT FROM AUTHOR]

Mixed transition metallic sulfides have attracted researchers' attention due to their unique electronic and electrochemical properties for energy storage devices. Herein, we have investigated nickel manganese sulfides (Nix–Mnx–S) based binary anode material for supercapattery devices. The hydrothermal method was used to synthesize the Nix–Mnx–S-based nanomaterials with different Ni to Mn ratios. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX), and Brunauer-Emmett-Teller spectroscopy (BETS) is used to examine surface characteristics, crystallinity, elemental analysis, and homogeneity. The electrochemical measurement of the Nix–Mnx–S-based electrode material is first explored in three electrodes assembly while maintaining a 1 M KOH electrolyte environment. Among all the electrodes, Ni0.50Mn0.50 S demonstrated exceptional performance with a specific capacity of 713 C/g or 1188 F/g at the current density of 1.0 A/g. Lastly, the Ni0.50Mn0.50 S based nanomaterials are used as working electrode and activated carbon (AC) as reference electrode for the two electrodes assembly test (Ni0.50 Mn0.50 S//AC). Which showing a high energy density of 35.24 (Wh/Kg), power density of 3200 (W/Kg), extraordinary specific capacity 158.6 C/g with coulomb efficiency 91.6% and capacity retention 70% after 11,000 galvanostatic charging/discharging (GCD) cycles. Our findings provide a platform to improve the performance of asymmetric energy storage devices. [ABSTRACT FROM AUTHOR]